16 research outputs found
Molecular analysis of intact preen waxes of Calidris canutus (Aves:Scolopacidae) by gas chromatography/mass spectrometry
The intact preen wax esters of the red knot Calidris canutus were studied with gas chromatography/mass spectrometry (GC/MS) and GC/MS/MS. In this latter technique, transitions from the molecular ion to fragment ions representing the fatty acid moiety of the wax esters were measured, providing additional resolution to the analysis of wax esters. The C-21-C-32 wax esters are composed of complex mixtures of hundreds of individual isomers. The odd carbon-numbered wax esters are predominantly composed of even carbon-numbered n-alcohols (C-14, C-16, and C-18) esterified predominantly with odd carbon-numbered 2-methyl fatty acids (C-7, C-9, C-11, and C-13), resulting in relatively simple distributions. The even carbon-numbered wax esters show a far more complex distribution due to a number of factors: (i) Their n-alcohol moieties are not dominated by even carbon-numbered n-alcohols esterified with odd carbon-numbered 2-methyl fatty acids, but odd and even carbon-numbered n-alcohols participate in approximately equal amounts; (ii) odd carbon-numbered methyl-branched alcohols participate abundantly in these wax ester clusters; and (iii) with increasing molecular weight, various isomers of the 2,6-, 2,8-, and 2,10-dimethyl branched fatty acids also participate in the even carbon-numbered wax esters. The data demonstrate that there is a clear biosynthetic control on the wax ester composition although the reasons for the complex chemistry of the waxes are not yet understood
2,6,10,15,19-Pentamethylicosenes in Methanolobus bombayensis, a marine methanogenic archaeon, and in Methanosarcina mazei
2,6,10,15,19-Pentamethylicosenes (PMEs) containing three to five double bonds have been found in the methanogenic archaea Methanosarcina mazei (DSM 3338), a strain isolated from sewage sludge, and in Methanolobus bombayensis (OCM 438), a non-extremophilic archaeon isolated from a marine sediment. This finding gives additional support for the use of compounds with the PME carbon skeleton as markers for methanogenic activity in marine environments. (C) 1997 Elsevier Science Ltd
Structural Identification of the Diester Preen-Gland Waxes of the Red Knot (Calidris canutus)
The intact C32-C48 diester wax esters of the preen gland of the migrating bird Calidris canutus are shown, using synthesized standards, to comprise predominantly C12-C16 alkane-1,2-diols esterified with octanoic, decanoic, and dodecanoic acid at one position, and with predominantly even-numbered carbon fatty acids at the other position.
Connecting biodiversity and potential functional role in modern euxinic environments by microbial metagenomics
14 páginas, 7 figuras, 3 tablas.Stratified sulfurous lakes are appropriate environments for studying the links between composition
and functionality in microbial communities and are potentially modern analogs of anoxic conditions
prevailing in the ancient ocean. We explored these aspects in the Lake Banyoles karstic area (NE
Spain) through metagenomics and in silico reconstruction of carbon, nitrogen and sulfur metabolic
pathways that were tightly coupled through a few bacterial groups. The potential for nitrogen
fixation and denitrification was detected in both autotrophs and heterotrophs, with a major role for
nitrogen and carbon fixations in Chlorobiaceae. Campylobacterales accounted for a large
percentage of denitrification genes, while Gallionellales were putatively involved in denitrification,
iron oxidation and carbon fixation and may have a major role in the biogeochemistry of the iron
cycle. Bacteroidales were also abundant and showed potential for dissimilatory nitrate reduction to
ammonium. The very low abundance of genes for nitrification, the minor presence of anammox
genes, the high potential for nitrogen fixation and mineralization and the potential for chemotrophic
CO2 fixation and CO oxidation all provide potential clues on the anoxic zones functioning. We
observed higher gene abundance of ammonia-oxidizing bacteria than ammonia-oxidizing archaea
that may have a geochemical and evolutionary link related to the dominance of Fe in these
environments. Overall, these results offer a more detailed perspective on the microbial ecology of
anoxic environments and may help to develop new geochemical proxies to infer biology and
chemistry interactions in ancient ecosystems.This research was funded by Grants GOS-LAKES
CGL2009-08523-E and DARKNESS CGL2012-32747 to
EOC from the Spanish Office of Science (MINECO), from
financial support by the Beyster Family Fund of the San
Diego Foundation and the Life Technologies Foundation
to the J Craig Venter Institute, and the NASA Astrobiology
Institute to CLD.Peer reviewe
Long-Term Preservation of Oil Spill Events in Sediments: The Case for the \u3cem\u3eDeepwater Horizon\u3c/em\u3e Oil Spill in the Northern Gulf of Mexico
Geochemical studies can provide a record of environmental changes and biogeochemical processes in sedimentary systems. Analytical methods are in need of high-throughput procedures targeting recalcitrant and multiple chemical species for delineating ecological patterns and ecosystem health. The goal of this chapter is to summarize the analytical methods, recalcitrant molecules and transformed organic material used in previous studies as chemical indicators of the impact and fate of Deepwater Horizon (DWH) oil residues in sediments. Further monitoring of recalcitrant molecules and transformed material will help to elucidate the long-term fate of the DWH weathered oil in sedimentary environments of the Gulf of Mexico (GoM)