Talk:C4 carbon fixation

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	C4 carbon fixation is within the scope of WikiProject Plants, an attempt to better organize information in articles related to plants and botany. For more information, visit the project page.
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[edit] Rewrite

This article isn't as good as it could be. I'm gonna try a basic rewrite. I got pretty far now, but I'm tired. I'll come back later and finish if no one else does in the meantime. This is an important adaptive strategy, and the quality of the article should reflect it! GuildNavigator84 12:05, 22 May 2006 (UTC)

[edit] Photorespiration

The cuurent article states, "But since otherwise tropical plants lose more than half of photosynthetic carbon in photorespiration, the C4 pathway is an adaptive mechanism for minimizing the loss." Does anyone have a citation for this? Often 25% is used as a hand-waving average number. Falkowski and Raven's book state, "In terrestrial C3 plants, which rely purely on diffusive CO2 suuply to Rubisco, photorespiratory consumption of O2 can easily be 25% of the activity of the enzyme in vivo (see Raven 1984)." 216.59.224.253 16:35, 30 June 2006 (UTC)

Yes. As far as I understand it: in a few experiments, photorespiration has resulted in the loss of up to 50% of fixed carbon. However, this was not the norm, as that sentence suggests. I think that 30% loss is above average, and is considered a bad day. The losses are significant, however, and cut two ways-- every time you photorespirate, you miss out on that opportunity for photosynthesis, so there's an opportunity cost of carbon fixation. However, there is also the additional cost that you have to use previously fixed carbon products to undo the results of the photorespiration, which makes it even worse. Gcolive 03:29, 1 August 2006 (UTC)

Hey, I am not sure if this qulifies as a source, but here is mention of seperate evolution of c-4 http://www.thegreatstory.org/convergence.pdf page 13 213.156.52.123 (talk) 09:18, 12 February 2008 (UTC)

I don't know whether to add it based on the "better than nothing" theory, but it would perhaps be better to cite the Simon Conway Morris book (if he mentions the C4 example, that is). This one doesn't go into much detail (for example, what are the 31 lines they mention), or subleties (how many genes need to change to switch C3 to C4? How much has the biochemistry of a random species been studied?), or cites which could lead to further digging. Summary: fine to add it if you want, as far as I'm concerned. Kingdon (talk) 21:52, 12 February 2008 (UTC)

[edit] Formatting of "C4"

I came here to find out whether it was C4 or C₄ plants. This article is inconsistent with itself. I added a contradiction tag. -203.171.67.232 (talk) 04:23, 30 March 2008 (UTC)

Don't know if that is the right tag for typography issues, but anyway C₄ (uppercase, not lowercase, C) seems to be right. At least, all the top hits in a google search for "C4 carbon fixation" used the subscript: [1] [2] [3] [4] [5] [6] [7]. Having said that, I'm not sure it is worth expecting 100% consistency (for example, as far as I know there is no technical way to put a subscript into the title of the wikipedia article, and some of those other sites seem to have similar constraints). If someone has better information on whether C₄ is in fact preferred (for example, if there is some style guide or something to consult), do speak up. Kingdon (talk) 06:27, 30 March 2008 (UTC)