1 00:00:15,379 --> 00:00:12,379 welcome to our ultimate webinar I've 2 00:00:17,570 --> 00:00:15,389 been waiting a while to say that now we 3 00:00:19,279 --> 00:00:17,580 have a slight technical problem so we 4 00:00:20,929 --> 00:00:19,289 won't be able to see James today unless 5 00:00:24,290 --> 00:00:20,939 miracles happen during the course of 6 00:00:26,210 --> 00:00:24,300 presentation so brief overview the 7 00:00:28,460 --> 00:00:26,220 slides for this presentation are already 8 00:00:30,200 --> 00:00:28,470 uploaded they're linked through the 9 00:00:34,130 --> 00:00:30,210 event link on the front of the website 10 00:00:36,650 --> 00:00:34,140 the document has just been updated so if 11 00:00:39,310 --> 00:00:36,660 you went to look at that link half an 12 00:00:42,229 --> 00:00:39,320 hour or so ago it would have been a 13 00:00:44,930 --> 00:00:42,239 relatively sparsely populated document 14 00:00:48,110 --> 00:00:44,940 it is now full of interesting words so I 15 00:00:50,029 --> 00:00:48,120 encourage you to go back to that this 16 00:00:52,910 --> 00:00:50,039 session is being recorded everything you 17 00:00:56,630 --> 00:00:52,920 say and type is going to be put out onto 18 00:00:58,400 --> 00:00:56,640 the internet and I think black is about 19 00:01:01,420 --> 00:00:58,410 that so I'm going to save myself into 20 00:01:04,119 --> 00:01:01,430 the background and pass over to James 21 00:01:07,039 --> 00:01:04,129 okay well what I want to talk about is 22 00:01:09,580 --> 00:01:07,049 what I think are relevant and pressing 23 00:01:14,390 --> 00:01:09,590 questions on the topic of the origin and 24 00:01:15,950 --> 00:01:14,400 early evolution photosynthesis you can 25 00:01:18,020 --> 00:01:15,960 see the first slide their introductory 26 00:01:20,570 --> 00:01:18,030 slide just some some very broad 27 00:01:21,830 --> 00:01:20,580 questions how soon after what we're 28 00:01:23,929 --> 00:01:21,840 trying to address here is how soon after 29 00:01:27,469 --> 00:01:23,939 the origin of life it photosynthesis 30 00:01:29,899 --> 00:01:27,479 arrives did simpler forms of like urban 31 00:01:32,420 --> 00:01:29,909 energy transduction proceed anoxygenic 32 00:01:34,460 --> 00:01:32,430 photosynthesis we are pretty sure a max 33 00:01:37,580 --> 00:01:34,470 genic photosynthesis preceded oxygen 34 00:01:39,590 --> 00:01:37,590 explosions when did organisms evolve 35 00:01:42,289 --> 00:01:39,600 oxygen influences and of course we have 36 00:01:44,590 --> 00:01:42,299 a fair bit of geological constraints on 37 00:01:48,380 --> 00:01:44,600 that topic and i'll mention some of it 38 00:01:50,420 --> 00:01:48,390 now that the title of this is origin and 39 00:01:52,490 --> 00:01:50,430 early evolution of photosynthesis and 40 00:01:53,990 --> 00:01:52,500 what I mean by early here is I'm 41 00:01:57,440 --> 00:01:54,000 basically just going up to the great 42 00:01:59,870 --> 00:01:57,450 oxidation event we don't you have 43 00:02:04,190 --> 00:01:59,880 something on the order of 2.4 billion 44 00:02:06,350 --> 00:02:04,200 years or so in age we're not I'm not 45 00:02:10,359 --> 00:02:06,360 really focused on photosynthetic 46 00:02:12,280 --> 00:02:10,369 eukaryotes and endosymbiosis all 47 00:02:14,350 --> 00:02:12,290 that which is all very interesting and 48 00:02:16,259 --> 00:02:14,360 very complicated in some ways that at 49 00:02:18,820 --> 00:02:16,269 least be your periods very complicated 50 00:02:21,100 --> 00:02:18,830 so I'm just not really prepared to talk 51 00:02:23,890 --> 00:02:21,110 about them there is of course the 52 00:02:25,600 --> 00:02:23,900 interesting aspect of oxygen rise in the 53 00:02:27,190 --> 00:02:25,610 neoproterozoic which almost certainly 54 00:02:30,640 --> 00:02:27,200 involves you care about our synthetic 55 00:02:35,110 --> 00:02:30,650 you carry it so it's a skip over them ok 56 00:02:38,319 --> 00:02:35,120 so moving on to the next slide just a 57 00:02:40,330 --> 00:02:38,329 summary of the net reactions of 58 00:02:42,430 --> 00:02:40,340 photosynthesis the first reaction you 59 00:02:45,910 --> 00:02:42,440 that you see there and it's not now I I 60 00:02:50,860 --> 00:02:45,920 suppose I don't know there's a pointer 61 00:02:52,119 --> 00:02:50,870 ok there we go students they say you 62 00:02:55,330 --> 00:02:52,129 should be able to see that green arrow 63 00:02:58,360 --> 00:02:55,340 if you're on Adobe Connect and you see 64 00:03:01,720 --> 00:02:58,370 the just the sort of generic net 65 00:03:06,190 --> 00:03:01,730 reaction for photosynthesis co 2 plus 2 66 00:03:09,970 --> 00:03:06,200 h 2 a where a sulfur oxygen number of 67 00:03:13,630 --> 00:03:09,980 nothing be hydrogen plus photons yields 68 00:03:17,289 --> 00:03:13,640 a reduced carbon in this case written in 69 00:03:20,349 --> 00:03:17,299 the in the form of what looks like 70 00:03:23,759 --> 00:03:20,359 formaldehyde but it's really Lukos and 71 00:03:28,330 --> 00:03:23,769 things advance work plus water plus some 72 00:03:32,770 --> 00:03:28,340 oxidized opponent how the original 73 00:03:35,220 --> 00:03:32,780 productive so the that's that's just the 74 00:03:38,379 --> 00:03:35,230 generic reaction for photosynthesis 75 00:03:41,650 --> 00:03:38,389 oxygenic photosynthesis synthesis of 76 00:03:46,000 --> 00:03:41,660 course the h-2a with the h2o wate water 77 00:03:47,740 --> 00:03:46,010 and we've the liberating oxygen this 78 00:03:51,039 --> 00:03:47,750 obviously the source of it in our 79 00:03:53,409 --> 00:03:51,049 atmosphere writing this there's never 80 00:03:59,349 --> 00:03:53,419 any action out in a bit more detail you 81 00:04:03,369 --> 00:03:59,359 see here the more detailed oxygen egg 82 00:04:05,080 --> 00:04:03,379 form of its showing that you're actually 83 00:04:09,099 --> 00:04:05,090 making glucose therefore of course you 84 00:04:11,470 --> 00:04:09,109 need more of everything oh and it just 85 00:04:13,869 --> 00:04:11,480 gets a bit more deal detail and traces 86 00:04:15,789 --> 00:04:13,879 the oxygen so the oxygen in the skip 2 87 00:04:18,819 --> 00:04:15,799 goes into the glucose the oxygen from 88 00:04:21,819 --> 00:04:18,829 the water goes into launched Michael 89 00:04:23,800 --> 00:04:21,829 oxygen in the atmosphere okay and 90 00:04:27,610 --> 00:04:23,810 oxygenic photosynthesis e 91 00:04:29,170 --> 00:04:27,620 is also very important and as I already 92 00:04:32,470 --> 00:04:29,180 mentioned probably preceded oxygen 93 00:04:35,350 --> 00:04:32,480 ecosystems really earth and there are a 94 00:04:41,770 --> 00:04:35,360 number of reductions possible there 95 00:04:45,610 --> 00:04:41,780 including sulfides hydrogen is in the 96 00:04:48,730 --> 00:04:45,620 wrong sulfides hydrogen and ferrous iron 97 00:04:50,860 --> 00:04:48,740 all of which of especially the ferrous 98 00:04:57,030 --> 00:04:50,870 iron sulfide very likely to have been 99 00:05:01,560 --> 00:04:57,040 abundant on the early Archaean earth and 100 00:05:06,580 --> 00:05:01,570 so these are all velopment process well 101 00:05:07,750 --> 00:05:06,590 hey going on to carbon isotopes so this 102 00:05:11,320 --> 00:05:07,760 is what I'm going to do is just give a 103 00:05:13,810 --> 00:05:11,330 brief introduction to what theological 104 00:05:17,350 --> 00:05:13,820 and this very brief introduction to what 105 00:05:20,620 --> 00:05:17,360 geological constraints we have on Rose 106 00:05:22,750 --> 00:05:20,630 emphasis and its occurrence and some of 107 00:05:25,810 --> 00:05:22,760 the most important of those are of 108 00:05:27,820 --> 00:05:25,820 course the carbon isotope record in 109 00:05:29,770 --> 00:05:27,830 sedimentary rocks and and by that I mean 110 00:05:32,920 --> 00:05:29,780 comparison of the carbonized protein 111 00:05:37,830 --> 00:05:32,930 carbonates versus organics in the same 112 00:05:41,170 --> 00:05:37,840 rocks and so the what you see here is 113 00:05:43,120 --> 00:05:41,180 just I just swiped this from the web 114 00:05:46,210 --> 00:05:43,130 item I didn't really have a handy pod 115 00:05:49,510 --> 00:05:46,220 for this and what you see here is Delta 116 00:05:51,300 --> 00:05:49,520 Z 13 of the organics relative to their 117 00:05:54,460 --> 00:05:51,310 should be peedee peedee belemnite 118 00:05:56,409 --> 00:05:54,470 burning and see that everything is 119 00:05:58,150 --> 00:05:56,419 negative so all these organics are 120 00:05:59,650 --> 00:05:58,160 negative off their negative in the range 121 00:06:01,990 --> 00:05:59,660 of kind of mind mostly in a range of 122 00:06:05,710 --> 00:06:02,000 minus 22 minus forty four mil relative 123 00:06:10,360 --> 00:06:05,720 carbonate and some of them going even 124 00:06:14,350 --> 00:06:10,370 lower than 60 or so per mil oh and this 125 00:06:16,629 --> 00:06:14,360 is all interpreted as evidence for 126 00:06:19,600 --> 00:06:16,639 carbon fixation in my carbon fixation 127 00:06:22,409 --> 00:06:19,610 could be via photosynthesis or it could 128 00:06:26,230 --> 00:06:22,419 be by some other form of auto trophy in 129 00:06:28,240 --> 00:06:26,240 when we talk about very old urban 130 00:06:33,159 --> 00:06:28,250 isotopes we don't really know what it is 131 00:06:35,740 --> 00:06:33,169 we know better when you go into the mid 132 00:06:37,850 --> 00:06:35,750 40 rizzo 'ok really photosynthetic and 133 00:06:40,109 --> 00:06:37,860 it certainly is in the phanerozoic 134 00:06:43,669 --> 00:06:40,119 photosynthesis is is creating this 135 00:06:49,319 --> 00:06:43,679 distribution box governess these these 136 00:06:53,059 --> 00:06:49,329 old August samples right here this is 137 00:06:54,929 --> 00:06:53,069 should be a cute from the Achille rocks 138 00:06:56,879 --> 00:06:54,939 or at least some of them are from 139 00:07:04,859 --> 00:06:56,889 achillea maybe some from ish with these 140 00:07:06,659 --> 00:07:04,869 are likely these are quite metamorphose 141 00:07:08,819 --> 00:07:06,669 rocks and so it's not entirely clear 142 00:07:10,859 --> 00:07:08,829 what has happened there it is possible 143 00:07:14,249 --> 00:07:10,869 that this is evidence for oxygen akoto 144 00:07:15,869 --> 00:07:14,259 synthesis that long ago we don't really 145 00:07:17,909 --> 00:07:15,879 know exactly how to interpret these 146 00:07:19,489 --> 00:07:17,919 there have been some other suggestions 147 00:07:25,229 --> 00:07:19,499 for how long could do this pre by up 148 00:07:27,509 --> 00:07:25,239 abiotic ly in fact that's not clear okay 149 00:07:31,379 --> 00:07:27,519 so but the main point is that there's a 150 00:07:33,149 --> 00:07:31,389 consistent record over quite essentially 151 00:07:36,659 --> 00:07:33,159 all of our history that we have in 152 00:07:39,979 --> 00:07:36,669 carbon isotopes of some kind of carbon 153 00:07:43,879 --> 00:07:39,989 fixation and quite possibly Photosynth 154 00:07:48,359 --> 00:07:43,889 ok these are figures from bill shops 155 00:07:50,819 --> 00:07:48,369 review paper in 2011 looking at the 156 00:07:54,029 --> 00:07:50,829 sites at which microfossils are 157 00:07:56,339 --> 00:07:54,039 collected and the carbon isotopes in the 158 00:07:57,929 --> 00:07:56,349 organics associated with those rocks in 159 00:08:00,509 --> 00:07:57,939 it in addition I will show the actual 160 00:08:02,189 --> 00:08:00,519 microphones date in a minute but again 161 00:08:03,719 --> 00:08:02,199 you see that in a number of these old 162 00:08:07,919 --> 00:08:03,729 sites from which microphones are 163 00:08:09,779 --> 00:08:07,929 collected are also similar carbon 164 00:08:13,109 --> 00:08:09,789 isotope values so on the order of minus 165 00:08:14,669 --> 00:08:13,119 20-30 famille relative to the carbonates 166 00:08:19,019 --> 00:08:14,679 you be in this case written correctly 167 00:08:21,689 --> 00:08:19,029 and same up here so this is just a 168 00:08:23,790 --> 00:08:21,699 broader span of time but again you see 169 00:08:27,359 --> 00:08:23,800 the same general trend but the 170 00:08:30,709 --> 00:08:27,369 interpretation generally is this is 171 00:08:35,610 --> 00:08:30,719 evidence for oxygen or at least 172 00:08:37,679 --> 00:08:35,620 photosynthesis need not be this down 173 00:08:39,839 --> 00:08:37,689 here need not be oxygen acota synthesis 174 00:08:43,049 --> 00:08:39,849 but it certainly some kind of 175 00:08:44,999 --> 00:08:43,059 photosynthesis but again we really can't 176 00:08:48,079 --> 00:08:45,009 just based on these carbon isotope 177 00:08:51,150 --> 00:08:48,089 values alone rule out other forms of 178 00:08:51,630 --> 00:08:51,160 chemo with Auto trophy expense or they 179 00:09:00,120 --> 00:08:51,640 can 180 00:09:03,120 --> 00:09:00,130 carbon with flow 13 okay these are some 181 00:09:05,160 --> 00:09:03,130 of the microfossils again just reviewing 182 00:09:06,800 --> 00:09:05,170 some of this the kind of evidence or 183 00:09:09,270 --> 00:09:06,810 what is presented as evidence for 184 00:09:12,930 --> 00:09:09,280 photosynthesis these are from the apex 185 00:09:16,560 --> 00:09:12,940 church about 3.45 or so billion years in 186 00:09:19,820 --> 00:09:16,570 western australia um various for 187 00:09:22,350 --> 00:09:19,830 micrographs and analyses in ramen 188 00:09:24,750 --> 00:09:22,360 showing arguing really develop chavez 189 00:09:28,610 --> 00:09:24,760 arguing here for for the similarity of 190 00:09:34,170 --> 00:09:28,620 these organisms or what he thinks are 191 00:09:36,120 --> 00:09:34,180 microfossils to cyanobacteria and it's 192 00:09:38,220 --> 00:09:36,130 certainly a possibility we don't know I 193 00:09:40,520 --> 00:09:38,230 think it's entirely clear chances 194 00:09:42,540 --> 00:09:40,530 definitely made the case that these are 195 00:09:47,550 --> 00:09:42,550 carbon these are truly organic 196 00:09:49,710 --> 00:09:47,560 containing microfossils there was quite 197 00:09:52,260 --> 00:09:49,720 a debate about that whether they are 198 00:09:55,110 --> 00:09:52,270 cyanobacteria or not is of course that 199 00:09:57,060 --> 00:09:55,120 is a much harder thing to determine may 200 00:10:00,060 --> 00:09:57,070 not even really be determinable at this 201 00:10:05,670 --> 00:10:00,070 point but problem morphologically they 202 00:10:07,380 --> 00:10:05,680 are similar but as my more biologically 203 00:10:08,820 --> 00:10:07,390 inclined colleagues will point out there 204 00:10:12,120 --> 00:10:08,830 are many things that can look like this 205 00:10:13,770 --> 00:10:12,130 so I mean I'm victory but the point is 206 00:10:16,560 --> 00:10:13,780 these these are in the rocks they 207 00:10:18,960 --> 00:10:16,570 definitely contain organics and it 208 00:10:20,640 --> 00:10:18,970 appears to be by organics so it's so 209 00:10:22,950 --> 00:10:20,650 it's very compelling evidence at three 210 00:10:24,900 --> 00:10:22,960 and a half million years for carbon 211 00:10:27,600 --> 00:10:24,910 fixers comments corps commander 212 00:10:32,040 --> 00:10:27,610 certainly wasn't possible photos 213 00:10:33,240 --> 00:10:32,050 innocence okay so a but I don't know if 214 00:10:34,560 --> 00:10:33,250 you guys can all hear me I assume you 215 00:10:39,870 --> 00:10:34,570 can't just jump in anytime with 216 00:10:42,000 --> 00:10:39,880 questions oh I'm totally accepted 217 00:10:44,040 --> 00:10:42,010 questions here these are some of the 218 00:10:46,260 --> 00:10:44,050 carbon isotopes I think this is 219 00:10:49,260 --> 00:10:46,270 basically all carbon isotopes reported 220 00:10:51,930 --> 00:10:49,270 for various microfossils of different 221 00:10:54,090 --> 00:10:51,940 ages of going from moderately recent 222 00:10:56,280 --> 00:10:54,100 stuff here Springs formation Australia 223 00:10:58,740 --> 00:10:56,290 850 million years the gunflint at one 224 00:11:02,130 --> 00:10:58,750 point nine billion all the way down to 225 00:11:03,810 --> 00:11:02,140 microfossils from 3.5 billion in the 226 00:11:04,860 --> 00:11:03,820 dresser formation again in Australia 227 00:11:08,550 --> 00:11:04,870 what's really 228 00:11:11,040 --> 00:11:08,560 and the same story basically you see the 229 00:11:14,160 --> 00:11:11,050 same kind of minus-30 remove all though 230 00:11:16,079 --> 00:11:14,170 these are getting quite light sorry when 231 00:11:19,710 --> 00:11:16,089 you're either getting quite like here 232 00:11:21,420 --> 00:11:19,720 the high then with fairly large error 233 00:11:23,810 --> 00:11:21,430 bars I I don't really know what what's 234 00:11:29,220 --> 00:11:23,820 going to happen there you be a pretty 235 00:11:32,040 --> 00:11:29,230 consistent finest 30 ish per mil value 236 00:11:36,810 --> 00:11:32,050 for these actual of minus-30 minus-40 237 00:11:39,240 --> 00:11:36,820 promote for these microfossils um the 238 00:11:41,040 --> 00:11:39,250 exceptionally perhaps being most recent 239 00:11:44,420 --> 00:11:41,050 water springs which are more than the 240 00:11:49,790 --> 00:11:44,430 mines 22 but the point is this these 241 00:11:53,670 --> 00:11:49,800 certainly look like evidence again for 242 00:11:57,900 --> 00:11:53,680 microfossils that's our carbon fixers in 243 00:12:03,540 --> 00:11:57,910 some form five good questions yes please 244 00:12:08,810 --> 00:12:03,550 pin sigmar this Bob Blankenship hi Bo hi 245 00:12:11,970 --> 00:12:08,820 if you can go back to that yeah um the 246 00:12:15,900 --> 00:12:11,980 carbon fractionation in the various 247 00:12:21,060 --> 00:12:15,910 anoxygenic photo shows has been looked 248 00:12:22,829 --> 00:12:21,070 at but not very extensively can you can 249 00:12:24,540 --> 00:12:22,839 you maybe remind us what sort of 250 00:12:27,810 --> 00:12:24,550 fractionation you get from things like 251 00:12:30,660 --> 00:12:27,820 green sulfur bacteria purple bacteria 252 00:12:32,960 --> 00:12:30,670 and so on which have at least the green 253 00:12:37,860 --> 00:12:32,970 sulfur's have a very different carbon 254 00:12:40,380 --> 00:12:37,870 fixation pathway yeah no I i do not have 255 00:12:43,490 --> 00:12:40,390 those numbers off the top of my head my 256 00:12:46,980 --> 00:12:43,500 understanding is that they're really not 257 00:12:49,230 --> 00:12:46,990 tremendously different but it's it's a 258 00:12:51,300 --> 00:12:49,240 reasonable question and I certainly can 259 00:12:53,490 --> 00:12:51,310 add that i do not have I haven't looked 260 00:12:54,720 --> 00:12:53,500 at that reason yeah that that was my 261 00:12:56,640 --> 00:12:54,730 understanding too but these that are 262 00:12:59,730 --> 00:12:56,650 down there about minus 40 are getting 263 00:13:02,100 --> 00:12:59,740 pretty pretty light yes indeed I it 264 00:13:05,130 --> 00:13:02,110 wasn't fair of those numbers no I 265 00:13:06,780 --> 00:13:05,140 actually was not either until I pulled 266 00:13:08,850 --> 00:13:06,790 up this paper and i have to say i'm 267 00:13:13,319 --> 00:13:08,860 frankly a little bit surprised allow 268 00:13:15,390 --> 00:13:13,329 that and yeah I I would be I would say 269 00:13:17,460 --> 00:13:15,400 take this with a grain of salt these are 270 00:13:18,510 --> 00:13:17,470 relatively recent results I know these 271 00:13:21,000 --> 00:13:18,520 did not exist 272 00:13:24,440 --> 00:13:21,010 as of ten years ago or whatever so 273 00:13:28,370 --> 00:13:24,450 they're relatively recent work and I 274 00:13:32,700 --> 00:13:28,380 like we can talk more about that but I 275 00:13:34,260 --> 00:13:32,710 would definitely take them as I said 276 00:13:38,150 --> 00:13:34,270 with a grain of salt I think they may 277 00:13:45,030 --> 00:13:41,580 there might be a place for her arguing 278 00:13:47,970 --> 00:13:45,040 to require some additional data of this 279 00:13:49,560 --> 00:13:47,980 sort yep which I think to be reasonably 280 00:13:52,760 --> 00:13:49,570 straightforward and you know all those 281 00:13:56,430 --> 00:13:52,770 cultures of the various groups of 282 00:13:58,860 --> 00:13:56,440 anoxygenic bacteria are available in 283 00:14:02,610 --> 00:13:58,870 various neighborhoods so I really I 284 00:14:04,740 --> 00:14:02,620 really mean it could be my I would be 285 00:14:07,380 --> 00:14:04,750 just shocked if that has not been that 286 00:14:11,570 --> 00:14:07,390 has not all been done on X and organisms 287 00:14:14,220 --> 00:14:11,580 I mean that would be pretty surprising 288 00:14:15,720 --> 00:14:14,230 but I really haven't I haven't looked so 289 00:14:22,260 --> 00:14:15,730 yeah it's just it's certainly worth 290 00:14:30,180 --> 00:14:22,270 pointing out i will make make a quick 291 00:14:34,160 --> 00:14:30,190 note of that okay let's see damn right 292 00:14:38,010 --> 00:14:34,170 here at this kevin writing are you Kim 293 00:14:42,420 --> 00:14:38,020 hey I'm the only paper I know was 294 00:14:46,280 --> 00:14:42,430 published in 1977 Bob you can was on 295 00:14:49,890 --> 00:14:46,290 that where they compared chloro biam 296 00:14:53,430 --> 00:14:49,900 thiosulfate Oh cillum with a purples and 297 00:14:55,110 --> 00:14:53,440 a climate amonos for good measure and I 298 00:14:58,200 --> 00:14:55,120 don't have the details like Laura biam 299 00:15:01,350 --> 00:14:58,210 was different as I recall okay if the 300 00:15:03,660 --> 00:15:01,360 ones all right interestingly everything 301 00:15:05,880 --> 00:15:03,670 else uses rubisco and Claudia this is 302 00:15:08,310 --> 00:15:05,890 reversed TCA cycle so clarity 303 00:15:11,040 --> 00:15:08,320 intelligent be enriched in carbon 304 00:15:12,900 --> 00:15:11,050 isotopes this is Linda Hayes yeah 305 00:15:16,020 --> 00:15:12,910 Caribbean because they reuse a reverse 306 00:15:17,550 --> 00:15:16,030 TCA cycle in the carbon fixation pathway 307 00:15:21,710 --> 00:15:17,560 the carbons that they have tend to be 308 00:15:27,030 --> 00:15:21,720 enriched how enriched irisha what I 309 00:15:29,960 --> 00:15:27,040 enriched in carbon 13 okay but what do 310 00:15:33,500 --> 00:15:29,970 you may have either okay I we're between 311 00:15:37,740 --> 00:15:33,510 I don't know 312 00:15:41,790 --> 00:15:37,750 10 per mil or so do you mean minus 10 313 00:15:43,770 --> 00:15:41,800 per mil or intentionally / / relative to 314 00:15:46,800 --> 00:15:43,780 other things that are using other carbon 315 00:15:51,180 --> 00:15:46,810 fixation red ribbon yeah that makes 316 00:15:53,100 --> 00:15:51,190 sense okay so that that is the error bar 317 00:15:55,620 --> 00:15:53,110 for many of these measurements on the 318 00:15:58,440 --> 00:15:55,630 microfossils you know sort of 10 / milk 319 00:16:00,030 --> 00:15:58,450 but that is a significant difference for 320 00:16:08,070 --> 00:16:00,040 definitely something we should have 321 00:16:11,490 --> 00:16:08,080 shown good point okay let's move on no 322 00:16:13,830 --> 00:16:11,500 more questions on carbon another 323 00:16:18,690 --> 00:16:13,840 constraint from the geological record is 324 00:16:21,750 --> 00:16:18,700 of course the what record we have of 325 00:16:25,590 --> 00:16:21,760 oxygen in the atmosphere and the banded 326 00:16:28,320 --> 00:16:25,600 iron formations themselves which is in 327 00:16:33,990 --> 00:16:28,330 this next figure I lost my pointer 328 00:16:36,780 --> 00:16:34,000 humans like I don't see their juice okay 329 00:16:40,710 --> 00:16:36,790 okay so they banded iron formations are 330 00:16:45,120 --> 00:16:40,720 here in red oxygen levels inferred are 331 00:16:47,570 --> 00:16:45,130 in blue and so it's pretty clear that 332 00:16:53,010 --> 00:16:47,580 something was causing ferrous iron to 333 00:16:57,810 --> 00:16:53,020 crash out and deposit as magnetite and 334 00:17:00,690 --> 00:16:57,820 hematite in the rtm and early 335 00:17:04,050 --> 00:17:00,700 proterozoic ocean exactly what the cause 336 00:17:06,570 --> 00:17:04,060 of that is is still debated and I mean 337 00:17:07,830 --> 00:17:06,580 one it is possible that it is at least I 338 00:17:11,040 --> 00:17:07,840 think it's still considered possible 339 00:17:12,840 --> 00:17:11,050 that it is simply the reaction of oxygen 340 00:17:16,610 --> 00:17:12,850 with ferrous iron aqueous reaction of 341 00:17:19,230 --> 00:17:16,620 oxygen with ferrous iron causing it to 342 00:17:24,660 --> 00:17:19,240 oxidizing that fares in turn or it could 343 00:17:28,110 --> 00:17:24,670 be could be somewhat more interesting 344 00:17:30,800 --> 00:17:28,120 and involve an oxygen accord isms that 345 00:17:36,480 --> 00:17:30,810 use ferrous iron as reductant and 346 00:17:38,490 --> 00:17:36,490 precipitate out feo h3 and and I think 347 00:17:41,510 --> 00:17:38,500 there is in fact iron isotope evidence I 348 00:17:44,640 --> 00:17:41,520 do not get a chance to pull that up but 349 00:17:46,320 --> 00:17:44,650 at some point there is in fact iron i'm 350 00:17:48,750 --> 00:17:46,330 quite sure there's ionized of evidence 351 00:17:50,279 --> 00:17:48,760 favor of the ladder and there's even a 352 00:17:54,240 --> 00:17:50,289 third possibility and that is the topic 353 00:17:56,639 --> 00:17:54,250 fatalis of ferrous iron complexes can 354 00:17:58,139 --> 00:17:56,649 also you can photo oxidized ferrous iron 355 00:18:00,120 --> 00:17:58,149 and surface water although there have 356 00:18:02,970 --> 00:18:00,130 been some arguments pretty substantial 357 00:18:05,759 --> 00:18:02,980 arguments against them but the bottom 358 00:18:09,960 --> 00:18:05,769 line is that the biss are it's a truly 359 00:18:13,350 --> 00:18:09,970 massive amount of iron and one really 360 00:18:16,669 --> 00:18:13,360 does have to understand how its formed 361 00:18:20,220 --> 00:18:16,679 why that ferrous iron was oxidized and 362 00:18:24,509 --> 00:18:20,230 it is either evidence for very oxygen 363 00:18:27,509 --> 00:18:24,519 early oxygenic photosynthesis or it as 364 00:18:31,789 --> 00:18:27,519 evidence for the ferrous iron the an 365 00:18:37,139 --> 00:18:31,799 oxygen combine their ferrous iron reduce 366 00:18:39,389 --> 00:18:37,149 oxygen so it's it's a interesting part 367 00:18:41,250 --> 00:18:39,399 of the story and I think we still don't 368 00:18:45,090 --> 00:18:41,260 know exactly how to interpret it in 369 00:18:48,360 --> 00:18:45,100 terms of photosynthesis particularly is 370 00:18:49,980 --> 00:18:48,370 this evidence I mean is it evidence for 371 00:18:53,039 --> 00:18:49,990 oxygenic photosynthesis I think that's 372 00:18:54,659 --> 00:18:53,049 really the issue that is oxygen in 373 00:18:59,840 --> 00:18:54,669 photosynthesis eating the archaean very 374 00:19:03,240 --> 00:18:59,850 early okay what else is on this slide 375 00:19:06,240 --> 00:19:03,250 alright they're just showing the roughly 376 00:19:09,509 --> 00:19:06,250 the time of arrival of various processes 377 00:19:11,370 --> 00:19:09,519 in organisms so again this is late rise 378 00:19:12,480 --> 00:19:11,380 in oxygen which we're not going to get 379 00:19:14,669 --> 00:19:12,490 into here but it's quite interesting 380 00:19:17,279 --> 00:19:14,679 really in the neoproterozoic is 381 00:19:22,049 --> 00:19:17,289 apparently associated with land-based 382 00:19:25,440 --> 00:19:22,059 eukaryotes he's over here and vascular 383 00:19:29,250 --> 00:19:25,450 plants transmitted later but the index 384 00:19:33,659 --> 00:19:29,260 emulator but it's it's a worthy topic 385 00:19:35,549 --> 00:19:33,669 and I just sort beyond completely beyond 386 00:19:41,060 --> 00:19:35,559 my knowledge I'm just not going to worry 387 00:19:49,259 --> 00:19:44,159 probably the most quantitative record we 388 00:19:50,940 --> 00:19:49,269 have for the occurrence of oxygen in the 389 00:19:53,159 --> 00:19:50,950 atmosphere is this mass independent 390 00:19:56,370 --> 00:19:53,169 fractionation of sulfur isotopes so this 391 00:19:58,830 --> 00:19:56,380 quantity here this cap 33s I guess most 392 00:19:59,650 --> 00:19:58,840 of you are familiar with this of me I 393 00:20:02,260 --> 00:19:59,660 know 394 00:20:04,690 --> 00:20:02,270 most part I don't want to get into a 395 00:20:08,470 --> 00:20:04,700 bunch of detail about this i work on 396 00:20:10,020 --> 00:20:08,480 this topic and it's you just be a bit of 397 00:20:13,840 --> 00:20:10,030 an aside for we've got at the moment but 398 00:20:19,360 --> 00:20:13,850 this is a measure this kappa delta 33 s 399 00:20:21,510 --> 00:20:19,370 is a measure of excess 33 sulfur in a 400 00:20:26,370 --> 00:20:21,520 given example that you're looking at and 401 00:20:30,370 --> 00:20:26,380 so in most samples you look in the first 402 00:20:33,550 --> 00:20:30,380 from essentially present-day up to 2.4 403 00:20:37,720 --> 00:20:33,560 or so billion years sedimentary rocks 404 00:20:40,390 --> 00:20:37,730 and virtually everything organisms all 405 00:20:43,990 --> 00:20:40,400 just everything we look at in sulfur 406 00:20:46,060 --> 00:20:44,000 isotopes has no unusual excess of 33 407 00:20:49,630 --> 00:20:46,070 sulfur it has the expected amount based 408 00:20:51,340 --> 00:20:49,640 on isotopic equilibrium arguments as 409 00:20:53,320 --> 00:20:51,350 arguments are applied to rocks normally 410 00:20:58,060 --> 00:20:53,330 but you can apply them to other things 411 00:21:01,030 --> 00:20:58,070 as well but when you go back beyond 2.4 412 00:21:06,700 --> 00:21:01,040 billion you suddenly see that's quite 413 00:21:10,090 --> 00:21:06,710 noticeable rise in excess 33s being 414 00:21:13,300 --> 00:21:10,100 positive 33 values and also in negative 415 00:21:14,860 --> 00:21:13,310 33 s values these are mostly in 416 00:21:19,680 --> 00:21:14,870 barrett's here there's a mostly in 417 00:21:22,060 --> 00:21:19,690 pyrites and there's a lot of speculation 418 00:21:23,290 --> 00:21:22,070 about what exactly is causing this 419 00:21:26,170 --> 00:21:23,300 interpretation that was offered 420 00:21:29,920 --> 00:21:26,180 initially and it is still essentially 421 00:21:33,430 --> 00:21:29,930 interpretation is that this reflects so2 422 00:21:37,600 --> 00:21:33,440 fatalis in the atmosphere and the 423 00:21:40,420 --> 00:21:37,610 difference was that here where you're 424 00:21:43,360 --> 00:21:40,430 seeing this signature there would photo 425 00:21:45,490 --> 00:21:43,370 eyes so you can photo ID SS or tune the 426 00:21:50,590 --> 00:21:45,500 atmosphere of volcanic so2 or whatever 427 00:21:52,810 --> 00:21:50,600 as o2 at any time but any prior to an 428 00:21:54,790 --> 00:21:52,820 oxygen oxygenated atmosphere when you 429 00:21:56,620 --> 00:21:54,800 photo eyes lettuce 02 you would produce 430 00:21:58,180 --> 00:21:56,630 two reservoirs essentially two 431 00:22:00,960 --> 00:21:58,190 reservoirs a sulfur one of them being 432 00:22:03,130 --> 00:22:00,970 elemental sulfur and the other sulfate 433 00:22:08,020 --> 00:22:03,140 once you've oxidized that as though two 434 00:22:10,540 --> 00:22:08,030 and all because all of the sulfur was 435 00:22:13,210 --> 00:22:10,550 not oxidized into one reservoir it is 436 00:22:15,399 --> 00:22:13,220 possible to produce an isotope effect 437 00:22:16,930 --> 00:22:15,409 in the Fatah lessness process this is 438 00:22:19,870 --> 00:22:16,940 the part that I work on in some detail 439 00:22:21,430 --> 00:22:19,880 in preserve it preserve it because you 440 00:22:23,350 --> 00:22:21,440 actually have two reservoirs you have 441 00:22:25,029 --> 00:22:23,360 the elemental sulfur msl fate and they 442 00:22:28,620 --> 00:22:25,039 don't do the same thing when they get 443 00:22:31,990 --> 00:22:28,630 into the ocean sedimentary environment 444 00:22:34,779 --> 00:22:32,000 now in present time and since we've had 445 00:22:38,080 --> 00:22:34,789 an oxygenated atmosphere all of the 446 00:22:40,990 --> 00:22:38,090 sulfur is regardless you can photo eyes 447 00:22:42,730 --> 00:22:41,000 so2 you photo eyes h2s cs2 anything that 448 00:22:45,669 --> 00:22:42,740 you put in the atmosphere sulfur bearing 449 00:22:47,440 --> 00:22:45,679 that is and you fertilize that or photo 450 00:22:49,210 --> 00:22:47,450 process it in any way it all ends up 451 00:22:51,310 --> 00:22:49,220 oxidized and converted into sulfuric 452 00:22:53,380 --> 00:22:51,320 acids you have one reservoir anything 453 00:22:57,399 --> 00:22:53,390 that you've done photochemically to 454 00:23:00,010 --> 00:22:57,409 impart a sulfur fractionation to that in 455 00:23:01,450 --> 00:23:00,020 any of those steps they simply erased 456 00:23:03,520 --> 00:23:01,460 because everything is added back 457 00:23:05,169 --> 00:23:03,530 together in stuck in one compound and 458 00:23:07,810 --> 00:23:05,179 that is essentially sulfuric acid 459 00:23:10,630 --> 00:23:07,820 sulphate so we lose that signature all 460 00:23:13,810 --> 00:23:10,640 through here but we still have it here 461 00:23:18,370 --> 00:23:13,820 and so this is used as a just a real 462 00:23:21,159 --> 00:23:18,380 hard marker for the rise of o2 in the 463 00:23:23,289 --> 00:23:21,169 atmosphere and it certainly is a very 464 00:23:26,590 --> 00:23:23,299 sensible interpretation there are 465 00:23:29,230 --> 00:23:26,600 details in terms of working out exactly 466 00:23:32,470 --> 00:23:29,240 whether you get the expected signatures 467 00:23:34,180 --> 00:23:32,480 from so2 fatalis and all laugh that one 468 00:23:35,740 --> 00:23:34,190 expects that one sees in the rocks do 469 00:23:37,659 --> 00:23:35,750 you get that when you you actually photo 470 00:23:41,649 --> 00:23:37,669 lies as it's in the lab of that bad as a 471 00:23:44,560 --> 00:23:41,659 in-depth and heavily worked on topic at 472 00:23:47,380 --> 00:23:44,570 the moment by myself included in my 473 00:23:49,960 --> 00:23:47,390 spectroscopy colleagues so oh but but 474 00:23:51,640 --> 00:23:49,970 right now the interpretation and I think 475 00:23:54,630 --> 00:23:51,650 it's quite reasonable is that this right 476 00:23:58,510 --> 00:23:54,640 here marks somewhere very close in here 477 00:24:01,720 --> 00:23:58,520 about 2.45 2.5 billion years marks the 478 00:24:03,779 --> 00:24:01,730 transition from very low low two levels 479 00:24:06,970 --> 00:24:03,789 less than kind of ppm levels to 480 00:24:12,760 --> 00:24:06,980 something above that so you know it 481 00:24:14,260 --> 00:24:12,770 might only be a 100 ppm or something 482 00:24:16,360 --> 00:24:14,270 that sort but it was high enough that it 483 00:24:18,130 --> 00:24:16,370 caused it affected by atmospheric 484 00:24:21,669 --> 00:24:18,140 processing of so2 and turned everything 485 00:24:23,620 --> 00:24:21,679 in this office ok so there's of course a 486 00:24:25,570 --> 00:24:23,630 relatively spotty record there are 487 00:24:26,799 --> 00:24:25,580 details that you hear different 488 00:24:29,470 --> 00:24:26,809 variations in the 489 00:24:30,700 --> 00:24:29,480 magnitude of the signature all all stuff 490 00:24:33,580 --> 00:24:30,710 that can be explained in various ways 491 00:24:35,860 --> 00:24:33,590 that I'm not going to get into now but 492 00:24:37,919 --> 00:24:35,870 it's a very powerful record and has had 493 00:24:40,810 --> 00:24:37,929 a profound impact and how we interpret 494 00:24:44,379 --> 00:24:40,820 oxygen the arrival of oxygen in the 495 00:24:46,600 --> 00:24:44,389 atmosphere okay so getting onto then 496 00:24:49,299 --> 00:24:46,610 photosynthesis so those are really i 497 00:24:50,470 --> 00:24:49,309 think the left out the iron isotope 498 00:24:52,480 --> 00:24:50,480 stuff but those are those other 499 00:24:53,950 --> 00:24:52,490 principal geological constraints your 500 00:24:56,680 --> 00:24:53,960 chemical constraints we have on 501 00:24:59,049 --> 00:24:56,690 photosynthesis I'll bet valve the oxygen 502 00:25:05,200 --> 00:24:59,059 you know the carbon isotopes for an 503 00:25:07,720 --> 00:25:05,210 oxygen oxygen species as well but ok so 504 00:25:11,259 --> 00:25:07,730 then what about photosynthesis of 505 00:25:15,129 --> 00:25:11,269 memphis is going to be just a very 506 00:25:17,529 --> 00:25:15,139 simple overview there are some experts 507 00:25:20,739 --> 00:25:17,539 on the phone here who i invite you to 508 00:25:22,629 --> 00:25:20,749 jump in and correct something if I don't 509 00:25:26,590 --> 00:25:22,639 say it enough detail if I say something 510 00:25:30,340 --> 00:25:26,600 incorrectly so this is what I'm showing 511 00:25:33,940 --> 00:25:30,350 here is one of the simplest light 512 00:25:35,799 --> 00:25:33,950 gathering systems we have it's it's not 513 00:25:38,109 --> 00:25:35,809 photosynthesis puces of our Dobson 514 00:25:41,739 --> 00:25:38,119 system this is for this is a light 515 00:25:47,859 --> 00:25:41,749 driven energy transduction system if you 516 00:25:50,499 --> 00:25:47,869 will and it's the so what I want from 517 00:25:53,039 --> 00:25:50,509 here is a membrane layer and light 518 00:25:56,799 --> 00:25:53,049 indicated by these yellow pulse 519 00:26:00,190 --> 00:25:56,809 lightning bolts and the rhodopsins take 520 00:26:02,769 --> 00:26:00,200 in the actually the broad out some 521 00:26:05,609 --> 00:26:02,779 protein is down here this little picture 522 00:26:09,489 --> 00:26:05,619 so it's a heptamer of alpha helixes 523 00:26:12,340 --> 00:26:09,499 connected by loops and inside in no of 524 00:26:15,009 --> 00:26:12,350 those alpha human sees is a retinal 525 00:26:17,529 --> 00:26:15,019 pigment so a carotenoid is hanging in 526 00:26:22,060 --> 00:26:17,539 there capable of absorbing visible light 527 00:26:24,070 --> 00:26:22,070 and this move that down to remember to 528 00:26:26,049 --> 00:26:24,080 move the right pointer ok there's the 529 00:26:29,919 --> 00:26:26,059 retinal there it absorbs a photon 530 00:26:31,149 --> 00:26:29,929 visible photon at an appropriate range 531 00:26:34,509 --> 00:26:31,159 of wavelengths and undergoes 532 00:26:39,850 --> 00:26:34,519 isomerization which allows for proton 533 00:26:40,480 --> 00:26:39,860 transduction through this through this 534 00:26:42,220 --> 00:26:40,490 channel 535 00:26:44,799 --> 00:26:42,230 to the roy thomson and so you actually 536 00:26:49,600 --> 00:26:44,809 get light-driven movements of protons 537 00:26:52,330 --> 00:26:49,610 into the cell and et pas which is also 538 00:26:56,020 --> 00:26:52,340 an integral membrane bound found 539 00:27:01,150 --> 00:26:56,030 structure is able to take those protons 540 00:27:03,730 --> 00:27:01,160 and use it to drive ATP synthesis ok so 541 00:27:06,400 --> 00:27:03,740 this is this is a it's really just it's 542 00:27:08,860 --> 00:27:06,410 a beautiful system it's so simple taking 543 00:27:10,419 --> 00:27:08,870 photon photo energy light energy and 544 00:27:12,970 --> 00:27:10,429 converting it directly into chemical 545 00:27:15,669 --> 00:27:12,980 energy used by the cell as we all know 546 00:27:18,070 --> 00:27:15,679 ATP is just you know of such fundamental 547 00:27:21,070 --> 00:27:18,080 importance in every single organism that 548 00:27:25,030 --> 00:27:21,080 we know it's almost hard to overstate it 549 00:27:31,030 --> 00:27:25,040 but so this really is a marvelously a 550 00:27:34,180 --> 00:27:31,040 simple and effective system for ion 551 00:27:36,100 --> 00:27:34,190 movement for I am transaction and it's 552 00:27:38,890 --> 00:27:36,110 we use for chloride ions used for 553 00:27:41,049 --> 00:27:38,900 protons as it's mentioned and it's it's 554 00:27:43,390 --> 00:27:41,059 fairly prevalent but it's not as 555 00:27:47,290 --> 00:27:43,400 prevalent as one might expect it's 556 00:27:48,850 --> 00:27:47,300 primarily in archaea I again when the 557 00:27:51,190 --> 00:27:48,860 audience here can correct me if I'm 558 00:27:53,520 --> 00:27:51,200 wrong about them it's also widespread 559 00:27:56,100 --> 00:27:53,530 and it's also widespread in certain 560 00:27:59,799 --> 00:27:56,110 proteobacteria these are the marine 561 00:28:01,480 --> 00:27:59,809 proteobacteria I think well yeah so it I 562 00:28:04,960 --> 00:28:01,490 mean that you know I have to say as 563 00:28:07,480 --> 00:28:04,970 someone who hasn't thought as much about 564 00:28:10,660 --> 00:28:07,490 these topics as some of you guys have I 565 00:28:12,910 --> 00:28:10,670 look at this and I just think why isn't 566 00:28:16,210 --> 00:28:12,920 this used in some fashion more I mean 567 00:28:19,120 --> 00:28:16,220 it's just so elegant and so you know I 568 00:28:21,280 --> 00:28:19,130 like the simplicity of it it just kind 569 00:28:25,510 --> 00:28:21,290 of surprised me but there are reasons I 570 00:28:26,740 --> 00:28:25,520 guess but it's and that this is Magnus 571 00:28:28,390 --> 00:28:26,750 spent too much time talking about this 572 00:28:29,919 --> 00:28:28,400 but one can't help but imagine that 573 00:28:33,549 --> 00:28:29,929 something like this would have developed 574 00:28:36,130 --> 00:28:33,559 certainly well before Anna oxygen ixora 575 00:28:38,590 --> 00:28:36,140 synthesis with its double photosystems 576 00:28:40,600 --> 00:28:38,600 no this is just so much input but of 577 00:28:42,730 --> 00:28:40,610 course this does not forget you reducing 578 00:28:44,830 --> 00:28:42,740 engine using equivalent so you're you're 579 00:28:47,890 --> 00:28:44,840 not Purdue you're not converting co2 580 00:28:51,549 --> 00:28:47,900 into those from from this process this 581 00:28:53,860 --> 00:28:51,559 is just to generate ATP okay so so 582 00:28:56,290 --> 00:28:53,870 that's okay you can you can you you can 583 00:28:59,020 --> 00:28:56,300 use that ATP to the dr of reverse 584 00:29:00,820 --> 00:28:59,030 electron flow to do reduction and so 585 00:29:03,430 --> 00:29:00,830 that's how the purple photosynthetic 586 00:29:05,799 --> 00:29:03,440 bacteria do it and so principal this 587 00:29:09,490 --> 00:29:05,809 could provide this could provide the 588 00:29:12,340 --> 00:29:09,500 energy for the carbon fixation practice 589 00:29:16,600 --> 00:29:12,350 I don't know of any organisms that are 590 00:29:19,270 --> 00:29:16,610 real photo autotrophic using wood option 591 00:29:23,620 --> 00:29:19,280 based photosynthesis it's just have a 592 00:29:27,000 --> 00:29:23,630 thing to give you enough of to to really 593 00:29:29,650 --> 00:29:27,010 power your whole your whole metabolism 594 00:29:32,500 --> 00:29:29,660 okay is that partly because it's not 595 00:29:36,430 --> 00:29:32,510 such a great collector or photons or is 596 00:29:38,500 --> 00:29:36,440 there some better reason for them well 597 00:29:40,240 --> 00:29:38,510 it only uses a fairly narrow region of 598 00:29:43,660 --> 00:29:40,250 the solar spectrum so you don't have a 599 00:29:45,640 --> 00:29:43,670 lot of of solar flux that you can 600 00:29:47,830 --> 00:29:45,650 harvest using these pigments although 601 00:29:49,840 --> 00:29:47,840 you could imagine that evolution could 602 00:29:52,030 --> 00:29:49,850 have broadened it out as it has in a lot 603 00:29:54,880 --> 00:29:52,040 of visual system exactly I don't have a 604 00:29:56,890 --> 00:29:54,890 good explanation for why I agree with 605 00:30:01,000 --> 00:29:56,900 you it's beautiful elegant simple system 606 00:30:04,930 --> 00:30:01,010 and it's it's surprising that you look 607 00:30:06,250 --> 00:30:04,940 out in the world is a purple but no it 608 00:30:09,220 --> 00:30:06,260 is the case that you look out in the 609 00:30:12,790 --> 00:30:09,230 world is me and so wow this is obviously 610 00:30:17,260 --> 00:30:12,800 an important and important and and 611 00:30:20,200 --> 00:30:17,270 possibly a very early assistant it 612 00:30:23,549 --> 00:30:20,210 hasn't become the dominant mode in the 613 00:30:29,830 --> 00:30:23,559 biosphere today obviously right right 614 00:30:32,110 --> 00:30:29,840 okay all right then the systems that are 615 00:30:34,299 --> 00:30:32,120 in fact dominant are just very 616 00:30:36,990 --> 00:30:34,309 generically indicated here again taking 617 00:30:38,860 --> 00:30:37,000 some taking figures just straight out of 618 00:30:41,980 --> 00:30:38,870 Homeland Marriott and Blankenship's 619 00:30:45,430 --> 00:30:41,990 paper 2011 nice review paper on 620 00:30:47,740 --> 00:30:45,440 evolution photosynthesis of what so 621 00:30:51,549 --> 00:30:47,750 what's shown here in this one labeled B 622 00:30:53,470 --> 00:30:51,559 is this is again photons coming into 623 00:30:55,870 --> 00:30:53,480 what's called a queue type reaction 624 00:31:01,090 --> 00:30:55,880 center the clinton phenol a known type 625 00:31:04,090 --> 00:31:01,100 reactions there and this is a very 626 00:31:06,970 --> 00:31:04,100 simple system in its utilizing cyclic 627 00:31:09,850 --> 00:31:06,980 electron flow okay so 628 00:31:13,659 --> 00:31:09,860 my pointer is here okay cyclic electron 629 00:31:16,360 --> 00:31:13,669 flow here and it's more or less i would 630 00:31:21,100 --> 00:31:16,370 say the simplest of the true 631 00:31:23,400 --> 00:31:21,110 photosynthetic systems not counting or 632 00:31:26,770 --> 00:31:23,410 dobson is a term photosynthetic system 633 00:31:29,880 --> 00:31:26,780 and although similar again in that it's 634 00:31:32,980 --> 00:31:29,890 really then you're just using this 635 00:31:38,980 --> 00:31:32,990 energy this proton gradient generated to 636 00:31:43,030 --> 00:31:38,990 use ATP okay and i think they remind me 637 00:31:48,310 --> 00:31:43,040 is this is a fair summary of the purple 638 00:31:51,669 --> 00:31:48,320 bacteria or is that not correct yeah 639 00:31:55,600 --> 00:31:51,679 that's true okay yeah that's not to be 640 00:31:58,390 --> 00:31:55,610 the purple bacteria okay papi right 641 00:32:02,860 --> 00:31:58,400 exactly okay and then the the lower one 642 00:32:05,020 --> 00:32:02,870 is now this is same situation photons 643 00:32:08,830 --> 00:32:05,030 coming in reaction center here now using 644 00:32:11,770 --> 00:32:08,840 I'm and sulfur cluster it's my iron 645 00:32:14,770 --> 00:32:11,780 sulfur type reaction Center so as 646 00:32:16,090 --> 00:32:14,780 opposed to the Q type known type 647 00:32:23,020 --> 00:32:16,100 reactions near here so different 648 00:32:26,230 --> 00:32:23,030 electron carrier and so that debate a 649 00:32:30,419 --> 00:32:26,240 great sulfur bacteria this is green 650 00:32:33,400 --> 00:32:30,429 sulfur yes and the point here is this is 651 00:32:37,299 --> 00:32:33,410 just creating reducing equivalents to be 652 00:32:41,110 --> 00:32:37,309 used in carbon and nitrogen fixation so 653 00:32:43,330 --> 00:32:41,120 this this really is so I guess what we 654 00:32:47,230 --> 00:32:43,340 would call it's closed for photosystem 1 655 00:32:48,940 --> 00:32:47,240 in some ways right that's right but you 656 00:32:52,000 --> 00:32:48,950 have to realize that those guys are also 657 00:32:53,830 --> 00:32:52,010 doing a cycle as well so there is a 658 00:32:56,650 --> 00:32:53,840 cycle there is a good I mean you have to 659 00:32:59,080 --> 00:32:56,660 return electrons right well I mean you 660 00:33:01,180 --> 00:32:59,090 need to pump protons to get to make ATP 661 00:33:04,390 --> 00:33:01,190 so so that's going to be going on as 662 00:33:06,669 --> 00:33:04,400 well Oh in addition to the electrons are 663 00:33:09,430 --> 00:33:06,679 going out of the cycle to drive carbon 664 00:33:10,690 --> 00:33:09,440 and nitrogen fixation right yeah like 665 00:33:12,850 --> 00:33:10,700 heaven says they're going to have both 666 00:33:15,870 --> 00:33:12,860 but interestingly I don't think we 667 00:33:18,100 --> 00:33:15,880 really understand that the kind of 668 00:33:19,930 --> 00:33:18,110 partitioning between those two modes of 669 00:33:20,740 --> 00:33:19,940 electrons flow very well and those kinds 670 00:33:24,880 --> 00:33:20,750 of organisms 671 00:33:28,750 --> 00:33:24,890 or at all yeah what we've understood in 672 00:33:32,530 --> 00:33:28,760 that respect Paul rank are the least 673 00:33:37,990 --> 00:33:32,540 understood in which you mean that's 674 00:33:42,370 --> 00:33:38,000 where you have both slow 23 reducing 675 00:33:44,710 --> 00:33:42,380 equivalents and leave return flow I'm 676 00:33:48,070 --> 00:33:44,720 not quite like like versus the noncyclic 677 00:33:51,490 --> 00:33:48,080 swollen and now that how that works in 678 00:33:54,070 --> 00:33:51,500 these organisms okay there's just a huge 679 00:34:03,510 --> 00:33:54,080 there's a huge gap in our understanding 680 00:34:10,930 --> 00:34:03,520 about that got you okay all right okay 681 00:34:12,430 --> 00:34:10,940 well this is just a generic view of 682 00:34:15,580 --> 00:34:12,440 reactions conventions engineer a 683 00:34:18,669 --> 00:34:15,590 schematic view of reaction centers again 684 00:34:21,909 --> 00:34:18,679 different different organisms here so 685 00:34:24,550 --> 00:34:21,919 the purple bacteria Diana bacteria this 686 00:34:26,320 --> 00:34:24,560 is a system to of the cyanobacterium 687 00:34:28,570 --> 00:34:26,330 photo system one of those nine bacteria 688 00:34:32,110 --> 00:34:28,580 and green sulfur bacteria and helio 689 00:34:33,520 --> 00:34:32,120 victory and the idea here is I'm not 690 00:34:37,090 --> 00:34:33,530 going to get into this any depth but 691 00:34:40,260 --> 00:34:37,100 just just to show what is what the 692 00:34:44,649 --> 00:34:40,270 reaction center actually looks like the 693 00:34:47,260 --> 00:34:44,659 each of these circles you see are an 694 00:34:51,460 --> 00:34:47,270 alpha helix so it's a membrane integral 695 00:34:56,260 --> 00:34:51,470 membrane spanning protein and there are 696 00:34:58,690 --> 00:34:56,270 each of these reaction centers okay this 697 00:35:01,380 --> 00:34:58,700 is what I'm referring to of this is the 698 00:35:04,330 --> 00:35:01,390 alpha helix here each of these circular 699 00:35:07,860 --> 00:35:04,340 turtles and each of these reaction 700 00:35:12,640 --> 00:35:07,870 centers is composed of a dimer of these 701 00:35:15,910 --> 00:35:12,650 transmembrane proteins five each dimer 702 00:35:19,150 --> 00:35:15,920 this case and some of the dimers are 703 00:35:21,040 --> 00:35:19,160 have some differences this that's what's 704 00:35:23,200 --> 00:35:21,050 indicated here by the red vs. blue so 705 00:35:27,280 --> 00:35:23,210 they refer to this is a heterodimer and 706 00:35:30,760 --> 00:35:27,290 some are very similar and preferred 707 00:35:32,440 --> 00:35:30,770 homodimer and i believe most of the the 708 00:35:33,970 --> 00:35:32,450 differences in the hetero versus 709 00:35:37,630 --> 00:35:33,980 homodimer are in 710 00:35:39,160 --> 00:35:37,640 we known transfer I understand that 711 00:35:42,790 --> 00:35:39,170 correctly which I I'm sure I have a 712 00:35:47,160 --> 00:35:42,800 rather simplistic understanding of that 713 00:35:50,050 --> 00:35:47,170 some antenna structures are here as well 714 00:35:52,810 --> 00:35:50,060 rate in the reaction center and the 715 00:35:56,530 --> 00:35:52,820 first there are as well there are more 716 00:36:00,510 --> 00:35:56,540 peripheral or distant light harvesting 717 00:36:05,109 --> 00:36:00,520 proteins pigments in the membrane also 718 00:36:07,330 --> 00:36:05,119 okay and so the idea here is just as you 719 00:36:10,420 --> 00:36:07,340 illustrate what these reaction centers 720 00:36:12,310 --> 00:36:10,430 look like there are many things in here 721 00:36:14,200 --> 00:36:12,320 as well i mean this is this is where you 722 00:36:15,460 --> 00:36:14,210 know this is really where the action is 723 00:36:19,420 --> 00:36:15,470 this is where the charge separation 724 00:36:23,349 --> 00:36:19,430 occurs and there are four knowns and 725 00:36:25,530 --> 00:36:23,359 chlorophylls this is what was known type 726 00:36:29,830 --> 00:36:25,540 reactions dinner here the Queen time 727 00:36:34,450 --> 00:36:29,840 various electron transfer transport 728 00:36:36,700 --> 00:36:34,460 elements and many of type I cannot do 729 00:36:39,250 --> 00:36:36,710 justice to this but and then when you 730 00:36:41,440 --> 00:36:39,260 move over to the to the more for a 731 00:36:43,210 --> 00:36:41,450 system one type but you type one 732 00:36:47,500 --> 00:36:43,220 reaction centers you see iron-sulfur 733 00:36:50,740 --> 00:36:47,510 clusters involved as well and again lots 734 00:36:53,349 --> 00:36:50,750 of stuff going on here a huge amount of 735 00:36:55,470 --> 00:36:53,359 work on this over the years and the 736 00:36:58,300 --> 00:36:55,480 evolution of this I would have to ask 737 00:37:01,300 --> 00:36:58,310 Bob or Kevin to speak to the evolution 738 00:37:03,340 --> 00:37:01,310 of these kinds of systems if they wish 739 00:37:06,460 --> 00:37:03,350 to because it's simply beyond my 740 00:37:10,240 --> 00:37:06,470 knowledge it's quite clear that there's 741 00:37:12,250 --> 00:37:10,250 been a lot of lateral gene transfer in 742 00:37:17,130 --> 00:37:12,260 these systems there they're related in 743 00:37:19,930 --> 00:37:17,140 many ways and fairly straightforwardly 744 00:37:21,970 --> 00:37:19,940 yeah I could just comment on a couple of 745 00:37:26,260 --> 00:37:21,980 things and then I'm sure Kevin campus of 746 00:37:29,080 --> 00:37:26,270 one of the key evolutionary development 747 00:37:32,140 --> 00:37:29,090 system is the issue of the dimer the 748 00:37:34,090 --> 00:37:32,150 heterodimerization of these systems so 749 00:37:37,690 --> 00:37:34,100 where you have the red and the blue 750 00:37:40,570 --> 00:37:37,700 there on the left that represents a 751 00:37:42,910 --> 00:37:40,580 heterodimer protein which is a protein 752 00:37:45,760 --> 00:37:42,920 that has resulted from a gene 753 00:37:47,770 --> 00:37:45,770 duplication and subsequent divergence to 754 00:37:50,560 --> 00:37:47,780 create two similar but not 755 00:37:52,930 --> 00:37:50,570 identical copies of the core reaction 756 00:37:56,890 --> 00:37:52,940 tennis pro key and you see that in the 757 00:38:00,250 --> 00:37:56,900 purples and in the cyano ps1 and ps2 but 758 00:38:02,470 --> 00:38:00,260 in the green sulfur bacteria Helio 759 00:38:04,360 --> 00:38:02,480 bacterium instead of bacteria you have 760 00:38:06,910 --> 00:38:04,370 what's called a homodimer and that's 761 00:38:10,060 --> 00:38:06,920 where you have a single gene that has 762 00:38:14,410 --> 00:38:10,070 not duplicated in so you have two copies 763 00:38:17,350 --> 00:38:14,420 of a single gene product that associate 764 00:38:19,720 --> 00:38:17,360 to form the reaction Center complex and 765 00:38:22,510 --> 00:38:19,730 that preventive represents an earlier 766 00:38:26,110 --> 00:38:22,520 form of evolution prior great gene 767 00:38:28,120 --> 00:38:26,120 duplication event so functionally what 768 00:38:32,350 --> 00:38:28,130 is the difference between the homo and 769 00:38:34,690 --> 00:38:32,360 heterodimer them well in the few types 770 00:38:36,430 --> 00:38:34,700 in the queue type so you have electron 771 00:38:40,300 --> 00:38:36,440 flow that goes down just one of those 772 00:38:44,890 --> 00:38:40,310 two branches down at the bottom left 773 00:38:48,370 --> 00:38:44,900 there just in the in the ps1 and Kevin 774 00:38:50,140 --> 00:38:48,380 can speak to this better than I you have 775 00:38:54,610 --> 00:38:50,150 you do have electron flow that goes down 776 00:38:57,490 --> 00:38:54,620 both both pathways and so the functional 777 00:39:00,010 --> 00:38:57,500 importance of the heterodimer in ps1 is 778 00:39:02,140 --> 00:39:00,020 is not very clear at least not to me all 779 00:39:04,650 --> 00:39:02,150 right and then the ones that are homo 780 00:39:08,770 --> 00:39:04,660 dimers almost certainly you have equal 781 00:39:10,990 --> 00:39:08,780 pathways such that either pathway can be 782 00:39:14,770 --> 00:39:11,000 op can be utilize but we don't have any 783 00:39:16,990 --> 00:39:14,780 real good structural data on those okay 784 00:39:20,200 --> 00:39:17,000 yeah yeah I would just add a bi agree 785 00:39:21,610 --> 00:39:20,210 with everything Bob just set for the 786 00:39:25,420 --> 00:39:21,620 type to reaction centers that the 787 00:39:27,400 --> 00:39:25,430 quinone sidekicks you type clearly the 788 00:39:28,990 --> 00:39:27,410 heterodimerization there is important 789 00:39:31,300 --> 00:39:29,000 first function to they only use one 790 00:39:34,600 --> 00:39:31,310 branch for like on transfer and they 791 00:39:36,430 --> 00:39:34,610 stabilize uh the semiquinone on the 792 00:39:38,070 --> 00:39:36,440 other side and then eventually double 793 00:39:42,010 --> 00:39:38,080 reduce it so that's part of their 794 00:39:43,810 --> 00:39:42,020 mechanism and I imagine that that header 795 00:39:45,640 --> 00:39:43,820 does that hitter a dimerization happened 796 00:39:47,830 --> 00:39:45,650 early on for those guys in fact it 797 00:39:49,630 --> 00:39:47,840 probably happened independently in the 798 00:39:52,570 --> 00:39:49,640 Lynn is leading the ps2 and the one 799 00:39:55,210 --> 00:39:52,580 leading to the Purple's for ps1 no it's 800 00:39:56,800 --> 00:39:55,220 a different case actually there even 801 00:39:58,690 --> 00:39:56,810 though they have heterodimers like Bob 802 00:40:00,730 --> 00:39:58,700 said we've shown for a while now that 803 00:40:01,570 --> 00:40:00,740 they use both sides and actually most 804 00:40:03,730 --> 00:40:01,580 the differences 805 00:40:05,350 --> 00:40:03,740 seem to be not in the middle with 806 00:40:07,870 --> 00:40:05,360 electron transfer is occurring but more 807 00:40:10,660 --> 00:40:07,880 on the outside in order to make a 808 00:40:12,460 --> 00:40:10,670 symmetric binding site optimized binding 809 00:40:15,040 --> 00:40:12,470 of electron donor acceptor is outside 810 00:40:16,780 --> 00:40:15,050 the membrane and actually some work that 811 00:40:19,210 --> 00:40:16,790 we've done in jungle because then it 812 00:40:20,530 --> 00:40:19,220 kind of agrees that they may have done 813 00:40:24,010 --> 00:40:20,540 this in response to the presence of 814 00:40:26,730 --> 00:40:24,020 oxygen II so that is that this one may 815 00:40:28,900 --> 00:40:26,740 have evolved from a homodimeric ancestor 816 00:40:30,910 --> 00:40:28,910 in response to the presence of oxygen 817 00:40:33,040 --> 00:40:30,920 that's that's an idea but I think it 818 00:40:36,010 --> 00:40:33,050 fits the data pretty well that's an 819 00:40:39,280 --> 00:40:36,020 interesting I would be good to test ok 820 00:40:40,540 --> 00:40:39,290 so the ok I'm not going to we're we're 821 00:40:43,210 --> 00:40:40,550 actually taking quite a bit of time I'm 822 00:40:45,820 --> 00:40:43,220 not going to go through the redox 823 00:40:47,440 --> 00:40:45,830 energies of these systems I think if 824 00:40:51,130 --> 00:40:47,450 somebody wants to see that in some 825 00:40:54,940 --> 00:40:51,140 detail just ask it's it's well known for 826 00:40:57,730 --> 00:40:54,950 the different systems to let me 827 00:40:59,800 --> 00:40:57,740 literally just get this for now this is 828 00:41:02,650 --> 00:40:59,810 what we are just discussing these are 829 00:41:04,930 --> 00:41:02,660 individual sorry I'm fine pointer these 830 00:41:06,700 --> 00:41:04,940 are individual alpha helixes here just 831 00:41:09,910 --> 00:41:06,710 showing the process possible 832 00:41:11,530 --> 00:41:09,920 evolutionary processes of fusion and 833 00:41:14,170 --> 00:41:11,540 duplication divergence all the different 834 00:41:15,730 --> 00:41:14,180 things that can go on genomically to 835 00:41:19,390 --> 00:41:15,740 create different types of reaction 836 00:41:20,860 --> 00:41:19,400 centers and so let's let's push on to 837 00:41:22,420 --> 00:41:20,870 what the questions are because we have 838 00:41:26,680 --> 00:41:22,430 this long list of questions to go 839 00:41:29,080 --> 00:41:26,690 through and so I'm literally I just 840 00:41:32,790 --> 00:41:29,090 copied the questions and I'm just going 841 00:41:39,820 --> 00:41:37,320 you know what small comments added so 842 00:41:41,500 --> 00:41:39,830 looking at the geochemical fossil 843 00:41:46,360 --> 00:41:41,510 evidence what are the big issues related 844 00:41:47,770 --> 00:41:46,370 to photosynthesis one is the carbon 845 00:41:49,840 --> 00:41:47,780 isotope signatures in these graphs 846 00:41:51,580 --> 00:41:49,850 fitting conclusions in old rocks the 847 00:41:54,520 --> 00:41:51,590 oldest rocks 3.8 billion year old rocks 848 00:41:56,770 --> 00:41:54,530 achillea are there about minus twenty to 849 00:42:00,250 --> 00:41:56,780 thirty primeau relative to carbonates 850 00:42:01,870 --> 00:42:00,260 has talked about initially which is it's 851 00:42:03,430 --> 00:42:01,880 consistent with thermal processing and 852 00:42:05,410 --> 00:42:03,440 photos and photosynthetic lead arrived 853 00:42:08,230 --> 00:42:05,420 organics but is can this be an abiotic 854 00:42:14,980 --> 00:42:08,240 process also and this has been looked at 855 00:42:15,520 --> 00:42:14,990 someone by some some folks but i think 856 00:42:17,350 --> 00:42:15,530 it's something 857 00:42:20,470 --> 00:42:17,360 needs to be addressed in even more 858 00:42:22,390 --> 00:42:20,480 detail and Jack Hills if we go to the 859 00:42:24,340 --> 00:42:22,400 jack hill zircons these are the oldest 860 00:42:27,220 --> 00:42:24,350 rocks if you will that we have the 861 00:42:28,750 --> 00:42:27,230 really minerals but they these jack 862 00:42:30,730 --> 00:42:28,760 hills in Western Australia these zircons 863 00:42:33,280 --> 00:42:30,740 are four point three to four point 864 00:42:36,850 --> 00:42:33,290 billion years old will it based on your 865 00:42:39,220 --> 00:42:36,860 aim led ages and they apparently I did 866 00:42:43,000 --> 00:42:39,230 not know this but they contain evidence 867 00:42:44,740 --> 00:42:43,010 they contain some I should say do they 868 00:42:48,520 --> 00:42:44,750 contain contemporaneous organic 869 00:42:51,010 --> 00:42:48,530 prophetic matter they do contain 870 00:42:53,050 --> 00:42:51,020 something that is they do contain some 871 00:42:54,340 --> 00:42:53,060 carbon whisper to them I whether it's 872 00:42:57,100 --> 00:42:54,350 truly contemporaneous or not I don't 873 00:42:59,620 --> 00:42:57,110 know if it is and it certainly would be 874 00:43:00,820 --> 00:42:59,630 good if it is then someone's going to 875 00:43:02,200 --> 00:43:00,830 measure the carbon isotopes at some 876 00:43:04,540 --> 00:43:02,210 point I don't think that's been done yet 877 00:43:08,080 --> 00:43:04,550 certainly should be done and if it comes 878 00:43:10,240 --> 00:43:08,090 out in this- 22-30 range is this again 879 00:43:12,400 --> 00:43:10,250 evidence for life and photosynthesis in 880 00:43:14,290 --> 00:43:12,410 this very early now we're talking about 881 00:43:16,150 --> 00:43:14,300 a very early window that's four point 882 00:43:19,540 --> 00:43:16,160 three to four point oh I mean this this 883 00:43:22,270 --> 00:43:19,550 is really the only handle we have at the 884 00:43:26,680 --> 00:43:22,280 present time on carbon isotopes from 885 00:43:28,510 --> 00:43:26,690 this pre 3.8 periods so the this it's 886 00:43:30,670 --> 00:43:28,520 very important to at least try to do 887 00:43:33,280 --> 00:43:30,680 these measurements and then we can argue 888 00:43:37,030 --> 00:43:33,290 about what it means if if it means 889 00:43:38,560 --> 00:43:37,040 anything but it's certainly there's no 890 00:43:41,460 --> 00:43:38,570 other way that I'm aware of to get at 891 00:43:45,160 --> 00:43:41,470 that time period on on earth apart from 892 00:43:47,620 --> 00:43:45,170 finding lunar crust blasted off in an 893 00:43:49,480 --> 00:43:47,630 impact on the moon from that age but 894 00:43:52,380 --> 00:43:49,490 good luck finding them I mean it's 895 00:43:54,880 --> 00:43:52,390 probably there would be hard to find oh 896 00:43:58,270 --> 00:43:54,890 ok another question are the apex Church 897 00:44:00,760 --> 00:43:58,280 microfossils really cyanobacteria how 898 00:44:03,100 --> 00:44:00,770 can we differentiate these we can't 899 00:44:04,660 --> 00:44:03,110 simply assert that they are because they 900 00:44:06,760 --> 00:44:04,670 happen to you know have some 901 00:44:09,070 --> 00:44:06,770 morphological similarity there has to be 902 00:44:10,600 --> 00:44:09,080 something a little better than that and 903 00:44:14,080 --> 00:44:10,610 I I don't know what that is but that's 904 00:44:16,540 --> 00:44:14,090 something that needs to be also dug into 905 00:44:18,310 --> 00:44:16,550 in a bit more detail he'll shops main 906 00:44:20,920 --> 00:44:18,320 they say that he's already but that's 907 00:44:23,740 --> 00:44:20,930 assault issue I don't know but it 908 00:44:25,300 --> 00:44:23,750 doesn't seem to me that it is before 909 00:44:26,860 --> 00:44:25,310 here were abandoned our information is 910 00:44:28,849 --> 00:44:26,870 primarily a product of xanax during 911 00:44:30,079 --> 00:44:28,859 photosynthesis using Ferris on okay 912 00:44:32,779 --> 00:44:30,089 is this is something being actively 913 00:44:34,700 --> 00:44:32,789 worked on the Iron isotopes and perhaps 914 00:44:36,950 --> 00:44:34,710 other methods as well so I think that 915 00:44:40,099 --> 00:44:36,960 there is there will be progress on that 916 00:44:41,769 --> 00:44:40,109 and has been something already and fell 917 00:44:44,690 --> 00:44:41,779 for mass independent fractionation 918 00:44:46,640 --> 00:44:44,700 argues for oxygen and photosynthesis by 919 00:44:49,309 --> 00:44:46,650 at least a two point four billion years 920 00:44:51,499 --> 00:44:49,319 well but how much earlier coulda did 921 00:44:53,660 --> 00:44:51,509 them and maybe this is maybe it's more 922 00:44:55,370 --> 00:44:53,670 accurate to this about 2.5 but you know 923 00:44:58,039 --> 00:44:55,380 what i'm talking about that break in the 924 00:45:00,410 --> 00:44:58,049 curve where you go from zero mass 925 00:45:02,089 --> 00:45:00,420 independent fractionation to to suddenly 926 00:45:05,599 --> 00:45:02,099 quite dramatic mass independent 927 00:45:06,890 --> 00:45:05,609 signatures I should I explain but how 928 00:45:09,499 --> 00:45:06,900 much how much earlier could this have 929 00:45:12,950 --> 00:45:09,509 been there is there is some evidence 930 00:45:15,170 --> 00:45:12,960 from transition metal abundances 931 00:45:17,930 --> 00:45:15,180 manganese in particular for small 932 00:45:22,059 --> 00:45:17,940 amounts the levels of oxygen at various 933 00:45:25,099 --> 00:45:22,069 times going back to about 2.5 maybe 2.7 934 00:45:28,970 --> 00:45:25,109 and you know it's possible that oxygenic 935 00:45:33,309 --> 00:45:28,980 photosynthesis was actively going on for 936 00:45:36,289 --> 00:45:33,319 quite some time but the oxygen was being 937 00:45:39,259 --> 00:45:36,299 titrated out by the ferrous iron in the 938 00:45:41,539 --> 00:45:39,269 ocean and did not have a chance to 939 00:45:44,150 --> 00:45:41,549 appear until a good chunk of that 940 00:45:46,249 --> 00:45:44,160 Sarah's iron was removed and in fact 941 00:45:48,620 --> 00:45:46,259 much of it is removed by to all of it 942 00:45:52,009 --> 00:45:48,630 but much of it is removed by by about 4 943 00:45:54,079 --> 00:45:52,019 2.5 or was it simply the case that there 944 00:45:58,819 --> 00:45:54,089 was no oxygen occurrences at that time 945 00:46:03,109 --> 00:45:58,829 from prior to point a 2.5 2.6 again we 946 00:46:05,299 --> 00:46:03,119 don't know oh and this this something 947 00:46:06,680 --> 00:46:05,309 that I originally once I mean many of us 948 00:46:08,960 --> 00:46:06,690 were very hopeful for these organic 949 00:46:13,700 --> 00:46:08,970 chemical markers of the hope and lloyds 950 00:46:17,029 --> 00:46:13,710 and things that sort of a representative 951 00:46:22,599 --> 00:46:17,039 of various membrane-bound of sterols and 952 00:46:26,720 --> 00:46:22,609 other fairly good-sized stable molecules 953 00:46:30,109 --> 00:46:26,730 these would be useful as markers of an 954 00:46:32,450 --> 00:46:30,119 oxygen and oxygen photosynthesis going 955 00:46:34,940 --> 00:46:32,460 back in time into early proterozoic into 956 00:46:36,529 --> 00:46:34,950 the archaean and that was indeed the 957 00:46:39,019 --> 00:46:36,539 case for a while or at least we thought 958 00:46:40,729 --> 00:46:39,029 so but the has been an issue of 959 00:46:42,530 --> 00:46:40,739 contamination regarding the 960 00:46:44,360 --> 00:46:42,540 interpretation of all of these organic 961 00:46:47,750 --> 00:46:44,370 since they've all but many of these 962 00:46:49,940 --> 00:46:47,760 organic to chemical markers and so the 963 00:46:51,680 --> 00:46:49,950 field that whole field is in a bit of a 964 00:46:52,790 --> 00:46:51,690 state of flux at the moment and I don't 965 00:46:55,340 --> 00:46:52,800 know exactly where that's going to go 966 00:46:58,790 --> 00:46:55,350 but it it certainly is an important 967 00:47:00,920 --> 00:46:58,800 component of all of this okay so what 968 00:47:02,630 --> 00:47:00,930 about prebiotic chemistry now and we're 969 00:47:06,320 --> 00:47:02,640 talking about origin and evolution of 970 00:47:08,810 --> 00:47:06,330 photosynthesis would you do it in a 971 00:47:11,000 --> 00:47:08,820 prebiotic sense at all and certainly it 972 00:47:13,190 --> 00:47:11,010 looks so complicated that that the 973 00:47:15,610 --> 00:47:13,200 answer is almost certainly no but we can 974 00:47:17,990 --> 00:47:15,620 ask some simple questions things like 975 00:47:21,350 --> 00:47:18,000 number one here were provided 976 00:47:23,000 --> 00:47:21,360 chromophore is present in the surface of 977 00:47:26,860 --> 00:47:23,010 the earth meaning for exams or wherever 978 00:47:29,000 --> 00:47:26,870 and that's certainly a plausible thing 979 00:47:31,130 --> 00:47:29,010 some carrots and LEDs are not that 980 00:47:34,250 --> 00:47:31,140 complicated they could be present in 981 00:47:39,790 --> 00:47:34,260 various forms for friends perhaps less 982 00:47:42,230 --> 00:47:39,800 so but even they are not wildly complex 983 00:47:44,740 --> 00:47:42,240 certainly more complicated than methane 984 00:47:47,180 --> 00:47:44,750 or something like that but it's not 985 00:47:49,570 --> 00:47:47,190 implausible to imagine having those some 986 00:47:52,520 --> 00:47:49,580 of those compounds present periodically 987 00:47:54,100 --> 00:47:52,530 we're simple electron chains possible so 988 00:47:57,770 --> 00:47:54,110 imagine now that you have you have 989 00:47:59,720 --> 00:47:57,780 membranes you have cells but you may 990 00:48:02,450 --> 00:47:59,730 still not have living systems would it 991 00:48:04,520 --> 00:48:02,460 be possible if it gets from some 992 00:48:09,680 --> 00:48:04,530 chromophores in those membranes you 993 00:48:13,030 --> 00:48:09,690 could perhaps do some excitation via 994 00:48:16,340 --> 00:48:13,040 photons and transport this is all very 995 00:48:19,070 --> 00:48:16,350 well tuned stuff now when we look at it 996 00:48:22,430 --> 00:48:19,080 all of the excitation transfer and all 997 00:48:24,110 --> 00:48:22,440 that that goes on in picking systems so 998 00:48:26,510 --> 00:48:24,120 to imagine the packages pop up 999 00:48:29,480 --> 00:48:26,520 periodically is perhaps so pushing it 1000 00:48:31,340 --> 00:48:29,490 but simpler forms of that are possible 1001 00:48:33,830 --> 00:48:31,350 unknowns are not that complicated 1002 00:48:36,260 --> 00:48:33,840 iron-sulfur clusters we know form can 1003 00:48:38,930 --> 00:48:36,270 form and plausibly prebiotic scenarios 1004 00:48:42,800 --> 00:48:38,940 so it is a sensible thing to consider I 1005 00:48:46,520 --> 00:48:42,810 would argue it delayed heavy bombardment 1006 00:48:48,800 --> 00:48:46,530 delay the onset of photosynthesis this 1007 00:48:50,450 --> 00:48:48,810 is the late heavy bombardment was just 1008 00:48:54,380 --> 00:48:50,460 to remind everybody you guys and you 1009 00:48:56,359 --> 00:48:54,390 must know was really from about 4.1 to 1010 00:49:01,420 --> 00:48:56,369 say 3.8 billion years 1011 00:49:03,769 --> 00:49:01,430 and in and of itself it would not have 1012 00:49:06,410 --> 00:49:03,779 created a molten earth or anything like 1013 00:49:09,980 --> 00:49:06,420 that it's it would just have created of 1014 00:49:11,440 --> 00:49:09,990 brief spikes of high temperatures and of 1015 00:49:14,539 --> 00:49:11,450 course melting if you're in the area 1016 00:49:16,400 --> 00:49:14,549 nearby where a large asked when he saw 1017 00:49:19,279 --> 00:49:16,410 asteroids asteroidal sized object is in 1018 00:49:21,859 --> 00:49:19,289 fact but if you if you do the later 1019 00:49:23,989 --> 00:49:21,869 bombardment does consider the 1020 00:49:25,099 --> 00:49:23,999 possibility of very large impactors say 1021 00:49:27,499 --> 00:49:25,109 on the order of several hundred 1022 00:49:30,529 --> 00:49:27,509 kilometers that could have vaporized the 1023 00:49:32,989 --> 00:49:30,539 oceans you vaporize the oceans you may 1024 00:49:36,349 --> 00:49:32,999 have to reset some of the biological 1025 00:49:39,620 --> 00:49:36,359 processes and some of it was present at 1026 00:49:41,509 --> 00:49:39,630 that time of the impact so it is 1027 00:49:43,220 --> 00:49:41,519 possible especially given the photos and 1028 00:49:45,890 --> 00:49:43,230 sizes are right there at the surface and 1029 00:49:51,279 --> 00:49:45,900 see everything going on near the service 1030 00:49:55,420 --> 00:49:51,289 that they could have felt the effects of 1031 00:49:57,440 --> 00:49:55,430 these kind of good sizing factors oh I 1032 00:49:59,599 --> 00:49:57,450 don't know how we're going to dress that 1033 00:50:01,190 --> 00:49:59,609 accepted by because of the early time 1034 00:50:04,549 --> 00:50:01,200 period accepted by those Jack Hills 1035 00:50:08,380 --> 00:50:04,559 zircon sort of measurements looking for 1036 00:50:11,390 --> 00:50:08,390 carbon other prebiotic questions were 1037 00:50:13,160 --> 00:50:11,400 integral membrane proteins as often 1038 00:50:15,890 --> 00:50:13,170 alpha should be alpha helix is produced 1039 00:50:17,660 --> 00:50:15,900 in an RNA DNA protein world certainly 1040 00:50:20,839 --> 00:50:17,670 they they shouldn't be made in our 1041 00:50:23,690 --> 00:50:20,849 anymore but they could be a product of 1042 00:50:26,029 --> 00:50:23,700 an RNA and protein world and even one 1043 00:50:29,180 --> 00:50:26,039 that is the thing on how you define life 1044 00:50:32,569 --> 00:50:29,190 it might still be a prebiotic growth but 1045 00:50:33,890 --> 00:50:32,579 one can convey that but they're not 1046 00:50:36,140 --> 00:50:33,900 alpha equals these are not that 1047 00:50:38,779 --> 00:50:36,150 complicated in there I mean it's a 1048 00:50:41,120 --> 00:50:38,789 certain set it prefers a certain set of 1049 00:50:44,390 --> 00:50:41,130 residues but it's they're fairly 1050 00:50:48,049 --> 00:50:44,400 straightforward and they can in some 1051 00:50:49,910 --> 00:50:48,059 cases pop in the membranes ok so now 1052 00:50:54,890 --> 00:50:49,920 getting into more of the evolution 1053 00:50:57,769 --> 00:50:54,900 questions and again I will my colleagues 1054 00:51:01,220 --> 00:50:57,779 and expand upon any of these that they 1055 00:51:03,259 --> 00:51:01,230 feel they would like to so origin of an 1056 00:51:05,870 --> 00:51:03,269 oxygen occurrences so it's presumably 1057 00:51:08,610 --> 00:51:05,880 from from earlier head of trophic or 1058 00:51:10,590 --> 00:51:08,620 team autotrophic organisms when I 1059 00:51:13,020 --> 00:51:10,600 the photosynthesis was though 1060 00:51:17,570 --> 00:51:13,030 synthesizers were the origin of life 1061 00:51:21,450 --> 00:51:17,580 that would be a bit pushing it but 1062 00:51:24,900 --> 00:51:21,460 indeed they could come from heterotrophs 1063 00:51:28,080 --> 00:51:24,910 and other things so questions related to 1064 00:51:30,120 --> 00:51:28,090 that then what what was the ancestral 1065 00:51:33,360 --> 00:51:30,130 reaction Center and what was its origin 1066 00:51:35,600 --> 00:51:33,370 the reaction centers as we just 1067 00:51:38,160 --> 00:51:35,610 discussed our complicated there remain 1068 00:51:40,320 --> 00:51:38,170 not crazy complicated but they're pretty 1069 00:51:43,050 --> 00:51:40,330 complicated and clearly they are well 1070 00:51:47,030 --> 00:51:43,060 evolved structures can one make of 1071 00:51:49,770 --> 00:51:47,040 reaction center with one or two 1072 00:51:53,100 --> 00:51:49,780 membrane-spanning proteins and can you 1073 00:51:55,530 --> 00:51:53,110 of begin to approach them of course you 1074 00:51:57,420 --> 00:51:55,540 have to find pigments and all that but 1075 00:52:01,560 --> 00:51:57,430 but that's the sort of question that one 1076 00:52:03,450 --> 00:52:01,570 wants to ask how was the ancestor reacts 1077 00:52:05,910 --> 00:52:03,460 under a simple homodimeric photosystem 1078 00:52:07,770 --> 00:52:05,920 okay I think Bob already answered that 1079 00:52:10,560 --> 00:52:07,780 scene saying it's pretty likely that 1080 00:52:12,990 --> 00:52:10,570 these moments home with America's moved 1081 00:52:19,020 --> 00:52:13,000 i'm eric reaction centers are thought to 1082 00:52:21,870 --> 00:52:19,030 be earlier did iron can plus sulfides or 1083 00:52:24,050 --> 00:52:21,880 other easily oxidizable compounds act as 1084 00:52:26,010 --> 00:52:24,060 primary donors in the reaction center 1085 00:52:27,450 --> 00:52:26,020 what we're looking for is evidence of 1086 00:52:31,770 --> 00:52:27,460 that that seems like a logical 1087 00:52:33,360 --> 00:52:31,780 assumption this I stole rate out of one 1088 00:52:36,300 --> 00:52:33,370 of Bob's papers just a marvelous 1089 00:52:37,910 --> 00:52:36,310 question for its directness and 1090 00:52:40,710 --> 00:52:37,920 simplicity with the last common ancestor 1091 00:52:43,770 --> 00:52:40,720 photosynthetic wonderful question I 1092 00:52:47,340 --> 00:52:43,780 don't know it's certainly seem sensible 1093 00:52:50,790 --> 00:52:47,350 but i don't know i think the edward it 1094 00:52:55,950 --> 00:52:50,800 though i think the answer's no yeah the 1095 00:52:57,420 --> 00:52:55,960 last common ancestry luca the reason i 1096 00:52:59,750 --> 00:52:57,430 say that is if you look at the 1097 00:53:04,020 --> 00:52:59,760 distribution of at least four co-based 1098 00:53:06,810 --> 00:53:04,030 photosynthesis in the tree you find it 1099 00:53:08,850 --> 00:53:06,820 all in the bacterial domain and then of 1100 00:53:12,680 --> 00:53:08,860 course the endosymbionts in the Eukarya 1101 00:53:15,450 --> 00:53:12,690 no virus single case of our keel 1102 00:53:20,160 --> 00:53:15,460 chlorophyll based photosynthesis but to 1103 00:53:22,430 --> 00:53:20,170 me that suggests that that the coracle 1104 00:53:25,700 --> 00:53:22,440 based photosynthesis was invented 1105 00:53:29,030 --> 00:53:25,710 within the bacterial domain and then 1106 00:53:32,359 --> 00:53:29,040 spread to the eukaryotes but you know 1107 00:53:34,069 --> 00:53:32,369 you you could get out of that if you 1108 00:53:36,430 --> 00:53:34,079 really wanted to but that's that's what 1109 00:53:40,849 --> 00:53:36,440 that distribution industry says to me 1110 00:53:42,140 --> 00:53:40,859 right right all right I rhodopsins more 1111 00:53:49,790 --> 00:53:42,150 ancient than photosynthetic reaction 1112 00:53:51,589 --> 00:53:49,800 centers I again the basis for the 1113 00:53:56,510 --> 00:53:51,599 question is because weird options and 1114 00:53:58,010 --> 00:53:56,520 their capability of generating a person 1115 00:54:00,440 --> 00:53:58,020 ingredients like driven both ingredients 1116 00:54:02,089 --> 00:54:00,450 are so so much simpler than 1117 00:54:05,870 --> 00:54:02,099 photosynthetic reaction centers one has 1118 00:54:08,690 --> 00:54:05,880 to ask are they in fact more ancestral 1119 00:54:11,359 --> 00:54:08,700 tomorrow did they appear earlier in an 1120 00:54:12,800 --> 00:54:11,369 evolutionary sense and I don't know that 1121 00:54:14,930 --> 00:54:12,810 we have any evidence one way or the 1122 00:54:16,370 --> 00:54:14,940 other for it but it sort of begs the 1123 00:54:19,730 --> 00:54:16,380 simplicity of the rhodopsin begs the 1124 00:54:21,530 --> 00:54:19,740 question did reaction center complex is 1125 00:54:23,510 --> 00:54:21,540 originated from a concatenation of one 1126 00:54:25,760 --> 00:54:23,520 helix proteins with pigment pigment 1127 00:54:29,210 --> 00:54:25,770 binding sites oh that's really one of 1128 00:54:31,430 --> 00:54:29,220 the figures from vin ver mas paper of it 1129 00:54:33,650 --> 00:54:31,440 certainly sounds plausible I I could not 1130 00:54:35,809 --> 00:54:33,660 really address this in detail but if 1131 00:54:40,630 --> 00:54:35,819 anyone bobrick doesn't want to add to 1132 00:54:44,599 --> 00:54:40,640 that expand upon them feel free to do so 1133 00:54:46,819 --> 00:54:44,609 sounds like a sensible thing this is 1134 00:54:50,030 --> 00:54:46,829 just a basic question about environment 1135 00:54:51,770 --> 00:54:50,040 really did oceanic photo zones before 1136 00:54:54,050 --> 00:54:51,780 2.4 in other words before we had an 1137 00:54:55,880 --> 00:54:54,060 oxygen atmosphere provide enough you've 1138 00:54:58,640 --> 00:54:55,890 each yielding to allow proteins nucleic 1139 00:54:59,960 --> 00:54:58,650 acids to avoid UV damage while 1140 00:55:01,730 --> 00:54:59,970 maintaining high in the physical folks 1141 00:55:04,309 --> 00:55:01,740 and maybe you can get around this with 1142 00:55:06,829 --> 00:55:04,319 you know some some pigment uv-absorbing 1143 00:55:09,559 --> 00:55:06,839 pigment things that can protect the 1144 00:55:11,120 --> 00:55:09,569 organism but if you did not have those 1145 00:55:13,160 --> 00:55:11,130 then you would have to be deep enough in 1146 00:55:19,370 --> 00:55:13,170 the ocean in the water column to avoid 1147 00:55:21,349 --> 00:55:19,380 significant UV damage all right origin 1148 00:55:23,329 --> 00:55:21,359 box Janek photosynthesis we're on we're 1149 00:55:25,730 --> 00:55:23,339 almost done yet Rome's down here from 1150 00:55:28,370 --> 00:55:25,740 and oxygen in photosynthesis oxygen 1151 00:55:30,770 --> 00:55:28,380 acromion oxygenic in seems like a 1152 00:55:33,859 --> 00:55:30,780 reasonable assumption that oxygen Hakeem 1153 00:55:35,329 --> 00:55:33,869 after an toxigenic just a few quick 1154 00:55:36,200 --> 00:55:35,339 questions here what was it selective 1155 00:55:38,530 --> 00:55:36,210 pressure for 1156 00:55:40,790 --> 00:55:38,540 meaning two types of reaction centers 1157 00:55:45,010 --> 00:55:40,800 and on service of it it seems like it's 1158 00:55:47,200 --> 00:55:45,020 simply that if you want to use water 1159 00:55:50,120 --> 00:55:47,210 source of electrons you're going to 1160 00:55:52,700 --> 00:55:50,130 union you're covering us fair span of 1161 00:55:54,920 --> 00:55:52,710 energy there so redox potential so you 1162 00:55:58,460 --> 00:55:54,930 you really do need some way to do that 1163 00:56:00,260 --> 00:55:58,470 but maybe that's a 19 point of view and 1164 00:56:03,650 --> 00:56:00,270 there's something some more so reason 1165 00:56:05,480 --> 00:56:03,660 for it oxygen equipment is arise from 1166 00:56:08,570 --> 00:56:05,490 arise from reaction center with a highly 1167 00:56:10,160 --> 00:56:08,580 oxidizing primary dinner other words 1168 00:56:13,579 --> 00:56:10,170 could you get away with just one 1169 00:56:17,990 --> 00:56:13,589 reaction Center have no idea answer that 1170 00:56:19,910 --> 00:56:18,000 is unlikely what driving forces led to 1171 00:56:21,380 --> 00:56:19,920 header dynamic reaction centers and this 1172 00:56:26,450 --> 00:56:21,390 gets back to a bit of our earlier 1173 00:56:28,220 --> 00:56:26,460 discussion oh and how did the that 1174 00:56:31,010 --> 00:56:28,230 sorry that should be though not a he how 1175 00:56:34,820 --> 00:56:31,020 did the oxygen-evolving complex evolved 1176 00:56:36,380 --> 00:56:34,830 of them just asking this question and I 1177 00:56:38,720 --> 00:56:36,390 i do not know anything about the 1178 00:56:41,740 --> 00:56:38,730 oxygen-evolving complex so if anyone 1179 00:56:45,230 --> 00:56:41,750 wants to comment on them please do and 1180 00:56:47,030 --> 00:56:45,240 finally again this is this is very 1181 00:56:48,440 --> 00:56:47,040 interesting question i believe i got it 1182 00:56:50,599 --> 00:56:48,450 from one of Bob's papers are there 1183 00:56:52,339 --> 00:56:50,609 undiscovered types of photosynthesis in 1184 00:56:55,250 --> 00:56:52,349 photosynthetic organisms presence on 1185 00:56:58,730 --> 00:56:55,260 earth today well certainly there were 1186 00:57:00,890 --> 00:56:58,740 some presence once upon a time and we 1187 00:57:02,690 --> 00:57:00,900 have long since lost that information 1188 00:57:04,250 --> 00:57:02,700 but are there are there any around today 1189 00:57:09,170 --> 00:57:04,260 I believe that was the point of the 1190 00:57:11,030 --> 00:57:09,180 question no bob is posing in that paper 1191 00:57:15,800 --> 00:57:11,040 but it certainly an interesting 1192 00:57:19,460 --> 00:57:15,810 possibility okay and I believe that that 1193 00:57:20,900 --> 00:57:19,470 is it we've gone for a full hour which 1194 00:57:27,050 --> 00:57:20,910 is a little longer than these usually go 1195 00:57:30,410 --> 00:57:27,060 for so add about the last point about 1196 00:57:33,200 --> 00:57:30,420 oxygen-evolving complex yeah I'm some 1197 00:57:37,790 --> 00:57:33,210 work from Woody Fisher Caltech is you 1198 00:57:39,380 --> 00:57:37,800 can interpret it in light of the idea 1199 00:57:41,420 --> 00:57:39,390 that you might have used manganese as an 1200 00:57:43,760 --> 00:57:41,430 electron donor like some mortgages still 1201 00:57:46,880 --> 00:57:43,770 use iron two electron donor now yes and 1202 00:57:49,910 --> 00:57:46,890 that may have occurred prior to the to 1203 00:57:52,250 --> 00:57:49,920 the horizon oxygen so you might have 1204 00:57:54,260 --> 00:57:52,260 reaction centers in which they were 1205 00:57:57,559 --> 00:57:54,270 using manganese is an electron just as 1206 00:57:59,329 --> 00:57:57,569 an electron donor and from that you know 1207 00:58:01,910 --> 00:57:59,339 if it became oxidizing enough you could 1208 00:58:03,859 --> 00:58:01,920 have involved an auction evolving 1209 00:58:05,690 --> 00:58:03,869 complex as the manganese the oxidized 1210 00:58:08,240 --> 00:58:05,700 making is bound to the reaction center 1211 00:58:10,730 --> 00:58:08,250 so you can gypsum Allen here at ASU is 1212 00:58:12,950 --> 00:58:10,740 doing some work on mutating purple 1213 00:58:15,470 --> 00:58:12,960 bacterial type 2 reaction centers to to 1214 00:58:19,099 --> 00:58:15,480 bind manganese you can actually see them 1215 00:58:20,059 --> 00:58:19,109 get oxidizing manganese okay that 1216 00:58:22,520 --> 00:58:20,069 they're not forming oxygen-evolving 1217 00:58:24,680 --> 00:58:22,530 complex of course but it's not so 1218 00:58:26,660 --> 00:58:24,690 far-fetched we actually tried to 1219 00:58:28,280 --> 00:58:26,670 determine if there were some modern 1220 00:58:31,400 --> 00:58:28,290 Santa bacteria international environment 1221 00:58:33,170 --> 00:58:31,410 that was oxidizing manganese in a hot 1222 00:58:36,109 --> 00:58:33,180 spring but we didn't really find any 1223 00:58:38,780 --> 00:58:36,119 evidence of that at least in sit you is 1224 00:58:41,870 --> 00:58:38,790 Lindsay work oh no sorry this is Nikki / 1225 00:58:43,970 --> 00:58:41,880 anto okay yep we're could identify yeah 1226 00:58:47,089 --> 00:58:43,980 sorry work with Beth person on that one 1227 00:58:50,059 --> 00:58:47,099 okay and could you say that one more 1228 00:58:51,740 --> 00:58:50,069 time please I oh sorry we were working 1229 00:58:54,829 --> 00:58:51,750 at a hot spring in Yellowstone that has 1230 00:58:59,030 --> 00:58:54,839 very high levels of manganese as well as 1231 00:59:01,700 --> 00:58:59,040 fe 2 and so we were asking you know do 1232 00:59:04,640 --> 00:59:01,710 these Santa bacteria use Fe to directly 1233 00:59:06,650 --> 00:59:04,650 and also do they use manganese and well 1234 00:59:09,289 --> 00:59:06,660 we found evidence that they did use fe 2 1235 00:59:11,569 --> 00:59:09,299 we didn't find any evidence of manganese 1236 00:59:15,410 --> 00:59:11,579 oxidation at least in scituate those 1237 00:59:18,079 --> 00:59:15,420 natural meds did you looked at any 1238 00:59:21,589 --> 00:59:18,089 oxygen excite have had a more of a 1239 00:59:23,720 --> 00:59:21,599 pressure look for electron donors uh 1240 00:59:25,400 --> 00:59:23,730 yeah there's chlorophyll exes and Rosie 1241 00:59:27,380 --> 00:59:25,410 flexus in there as well but they're not 1242 00:59:30,589 --> 00:59:27,390 doing anything you're growing photo 1243 00:59:35,270 --> 00:59:30,599 heterotrophic play usually they are ok 1244 00:59:37,940 --> 00:59:35,280 thanks ok and this is Nikki right yeah 1245 00:59:42,380 --> 00:59:37,950 yeah yes ok I see you I just now noticed 1246 00:59:44,150 --> 00:59:42,390 your comment about the hydraulic 1247 00:59:46,339 --> 00:59:44,160 appropriate pathway for chlorophyll 1248 00:59:49,010 --> 00:59:46,349 excess carbon isotopes about minus 15 1249 00:59:50,690 --> 00:59:49,020 per mil so yeah that is that is about 10 1250 00:59:55,870 --> 00:59:50,700 / no less than 1251 01:00:02,210 --> 00:59:59,870 all right okay any other questions shall 1252 01:00:03,710 --> 01:00:02,220 we and again I apologize for not having 1253 01:00:04,910 --> 01:00:03,720 I have two cameras sitting here attached 1254 01:00:08,210 --> 01:00:04,920 to my computer and I could not get 1255 01:00:14,839 --> 01:00:08,220 either one working so we just had to do 1256 01:00:19,040 --> 01:00:14,849 this by voice okay if no other questions 1257 01:00:23,420 --> 01:00:19,050 I think we're all set current kids thank 1258 01:00:27,800 --> 01:00:23,430 you very much okay they are very much so 1259 01:00:29,210 --> 01:00:27,810 wrapping up our our series here lindsey 1260 01:00:33,770 --> 01:00:29,220 is going to be sending out an email 1261 01:00:37,160 --> 01:00:33,780 shortly on next steps because we know 1262 01:00:40,010 --> 01:00:37,170 that you will miss us if we didn't so 1263 01:00:41,750 --> 01:00:40,020 expect to hear from the shortly and and 1264 01:00:44,660 --> 01:00:41,760 then we'll be outlining the next steps 1265 01:00:47,240 --> 01:00:44,670 in the process after lap so thank you