@article {717,
	title = {Carbon-isotopic shifts associated with heterotrophy and biosynthetic pathways in direct- and indirect-developing sea urchins},
	journal = {Marine Ecology Progress Series},
	volume = {275},
	year = {2004},
	note = {847vnTimes Cited:4Cited References Count:34},
	pages = {139-151},
	abstract = {Natural abundances of C-13 were measured in bulk biomass and in individual lipids isolated from 2 species of sea urchins, Heliocidaris erythrogramma and H. tuberculata, and from calcareous and green benthic algae on which they were feeding. Planktonic larvae of H. erythrogramma are lecithotrophic whereas those of H. tuberculata are planktotrophic. The organisms were collected from a subtidal environment in Botany Bay, Sydney, Australia. The biomass of both consumers was enriched in C-13 relative to their diets by up to 1.8parts per thousand. The carbon skeletons of sterols from the urchins derive at least in part from de novo biosynthesis by the urchins. Depending on chain length and degree of unsaturation, carboxylic acids from the urchins derive from de novo blosynthesis (14:0, unsaturated acids), from the diet (18:0), or from both these sources (16:0). H. tuberculata synthesizes a greater distribution and proportion of unsaturated carboxylic acids. Odd-C and branched-chain carboxylic acids derive in part from bacterial sources and are enriched in C-13 relative to algal lipids and depleted relative to those in urchins. Only H. erythrogramma, which uses wax esters-as storage lipids in its relatively large and buoyant eggs, produces significant quantities of n-alkanols; n-alkanols in H, tuberculata derive from the diet. In terms of molecular distributions and isotopic compositions, the lipids in fecal matter from both heterotrophs resemble those of the diet rather than those of the urchins.},
	issn = {0171-8630},
	doi = {10.3354/meps275139},
	author = {Villinski, J. C. and Hayes, J. M. and Villinski, J. T. and Brassell, S. C. and Raff, R. A.}
}
@article {1003,
	title = {Algal and archaeal polyisoprenoids in a recent marine sediment: Molecular isotopic evidence for anaerobic oxidation of methane},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {2},
	year = {2001},
	note = {458jvTimes Cited:51Cited References Count:79},
	month = {Jan 17},
	abstract = {Analyses of C-13 contents of individual organic molecules in a marine sediment show that crocetane, 2,6,11,15-tetramethylhexadecane, an isomer of phytane, is produced by microorganisms that use methane as their main source of carbon. The sediments lie at a water depth of 68 m in the Kattegat, the strait between Denmark and Sweden. Crocetane appears first 185 cm below the sediment-water interface, in the zone marking the transition from sulfate reduction to methanogenesis. Its delta C-13 value is -90 +/- 10 parts per thousand versus Vienna Pee Dee Belemnite (VPDB). Its structure, which includes four isoprene units arranged symmetrically around a tail-to-tail linkage, suggests that it is produced by a member of the archaea. Growing at the intersection of the diffusion gradients for sulfate and methane in sedimentary pore waters, the source organism apparently function as a methane-consuming member of the microbial consortium responsible for the anaerobic oxidation of methane [Hoehler et al., 1994], in which, as first demonstrated quantitatively in these sediments [Iversen and Jorgensen, 1985], electrons are transferred from methane to sulfate. The presence of archaeal biomass throughout the sediment section is indicated by significant concentrations of 2,6,10,15,19-pentamethylicosane (PMI) and of ether-bound phytane and biphytane. The PMI reaches a minimum delta value of -47 parts per thousand well below the transition zone. Its isotopic depletion could reflect either methanogenic or methanotrophic sources. The ether-bound lipids are isotopically uniform throughout the section and are presumed to derive from archaea that utilize a carbon source unaffected by the oxidation of methane.},
	issn = {1525-2027},
	doi = {10.1029/2000GC000112},
	author = {Bian, L. Q. and Hinrichs, K. U. and Xie, T. M. and Brassell, S. C. and Iversen, H. and Fossing, H. and Jorgensen, B. B. and Hayes, J. M.}
}
