485 research outputs found
Ecdysteroids. Selective Protections and Synthesis of Potential Tools for Biochemical Studies
B-Ecdysone and cyasterone bave been transformed into the ecdysterone analogue 4, wbich carries a [3-(p-hydroxyphenyl).-propoxylj- group at the end of the side chain. This derivative should be useful for various biochemical investigations (I-labelling, affinity chromatography), since it exhibits a marked ecdysterone-like activity in two independent biological tests. The synthetic scheme makes use of highly selective protections of the hydroxyl groups of phytoecdysteroids
Presence of an unusual 17α,21β(H)-bacteriohopanetetrol in Holocene sediments from Ace Lake (Antarctica)
Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Organic Geochemistry 39 (2008): 1029-1032, doi:10.1016/j.orggeochem.2008.01.008.Whilst investigating the intact biohopanoid (bacteriohopanepolyol, BHP) distribution in
Holocene sediments from Ace Lake (Antarctica), we have identified the presence of ab-
bacteriohopanetetrol in sediments aged up to 9400 years BP. To our knowledge, this is
the first time that an intact polyfunctionalised BHP with the “geological” 17α,21β(H)
configuration has been identified in a sediment. Previously, this structure has only been
observed in species of the nitrogen fixing bacterium Frankia. Its presence here in the
sedimentary environment has implications for the interpretation of hopanoid ββ/αβ
ratios in the geological record.This work
was supported by grants from the Australian Antarctic Science Advisory Committee
(1166 to J.V.) and the Netherlands Organization for Scientific Research (NWO;
851.20.006 to J.S.S.D. and NWO-VENI grant 016.051.014 to M.J.L.C.) We gratefully
acknowledge the NERC for funding (HMT) and The Science Research Infrastructure
Fund (SRIF) from HEFCE for funding the purchase of the Thermo Electron Finnigan
LCQ ion trap mass spectrometer
Signatures of arithmetic simplicity in metabolic network architecture
Metabolic networks perform some of the most fundamental functions in living
cells, including energy transduction and building block biosynthesis. While
these are the best characterized networks in living systems, understanding
their evolutionary history and complex wiring constitutes one of the most
fascinating open questions in biology, intimately related to the enigma of
life's origin itself. Is the evolution of metabolism subject to general
principles, beyond the unpredictable accumulation of multiple historical
accidents? Here we search for such principles by applying to an artificial
chemical universe some of the methodologies developed for the study of genome
scale models of cellular metabolism. In particular, we use metabolic flux
constraint-based models to exhaustively search for artificial chemistry
pathways that can optimally perform an array of elementary metabolic functions.
Despite the simplicity of the model employed, we find that the ensuing pathways
display a surprisingly rich set of properties, including the existence of
autocatalytic cycles and hierarchical modules, the appearance of universally
preferable metabolites and reactions, and a logarithmic trend of pathway length
as a function of input/output molecule size. Some of these properties can be
derived analytically, borrowing methods previously used in cryptography. In
addition, by mapping biochemical networks onto a simplified carbon atom
reaction backbone, we find that several of the properties predicted by the
artificial chemistry model hold for real metabolic networks. These findings
suggest that optimality principles and arithmetic simplicity might lie beneath
some aspects of biochemical complexity
Tapping the archives: The sterol composition of marine sponge species, as determined non-invasively from museum preserved specimens, reveals biogeographical features
Over 8600 species are currently recorded in the phylum Porifera (sponges). They produce a large diversity of biochemical compounds including sterols, with more than 250 different sterols identified. Some of these sterols are of great interest, due to their use for fingerprinting in ecological and biomarker (molecular fossil) studies. As a large number of identified extant species from biodiversity surveys are housed in museum collections, preserved in ethanol, these present a potentially rich source of identified specimens for comparative lipid analyses. Here, we show that, in at least one species, sterol distributions obtained from the ethanol used to preserve specimens of sponges were representative, and comparable to the sterol distribution obtained from wet-frozen and from freeze-dried tissue from the same species. We employed both GC-MS and two-dimensional gas chromatography-time-of-flight mass spectrometry (GCĂ—GC-TOFMS), with an improved signal-to-noise ratio for even minor constituents. Analysis of two additional specimens of the same species, but of different provenance, resulted in detection of marked differences in sterol composition, which could be attributed to variations in geography, environmental conditions, microbial communities, diet or cryptic speciation. The possibility of using ethanol from identified, preserved museum sponges could drastically increase the number of available samples. This could enable the study of their sterol complements, and the detailed investigation of differences due to geographical and oceanographic, phylogenetic, and other factors in unprecedented detail
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