Biomarker sterol

Soils have also been examined directly, not for evidence of possible contamination, but as a study of manuring practice in medieval to early modern Orkney, Scotland. The sterols campesterol, sitosterol, and 5/1-stigmastanol were used as biomarkers for ruminant animal manure and coprostanol for omnivorous animal manure, with hyodeoxycholic acid used to further define the manure as coming from pigs (Bull et al. 1999, Simpson et al. 1999). It is rare to be able to extract sterols from such samples because their natural abundance is generally low. If they can be found, however, then they are useful as unambiguous biomarkers for either plants or animals. 

The example of a total extract composition of a tropical soil from the Amazon, Brazil, shows mycose as the major compound, numerous other monosaccharides, lipid components such as fatty acids and fatty alcohols, and natural product biomarkers (Fig. 9a). The mycose and elevated levels of the other saccharides reflect the efficient fungal/microbial degradation of plant detritus in the tropics. This can be compared to the saccharides in the soil from an almond orchard in California, where glucose and mycose are the main sugars with lipids, sterols and triterpenoids (Fig. 9b, ). 

Figure 9.15 Chemical structures of some of the important sterols used as biomarkers in estuaries (e.g., /3-sistosterol, stigmasterol, campesterol, brassicasterol, and cholesterol).

Canuel et al., 1997). This recurring theme of overlapping sterol markers in different organic matter sources indicates that caution should be advised when using sterols solely to distinguish between land and aquatic sources (Volkman, 1986 Jaffe et al., 2001). Instead, biomarker source identifications should be corroborated across lipid compound classes and using bulk and compound-specific isotope analysis. 

Lipids are an important component of organic matter with a diversity of compound classes (e.g., hydrocarbons, fatty acids, n-alkanols, and sterols) that have been used as effective biomarkers of organic matter in coastal and estuarine systems. These compounds are water insoluble compounds that typically... 

Sterols and their respective derivatives have proven to be important biomarkers that can be used to estimate algal and terrestrial contributions as well as dia-genetic proxies. These compounds are a group of lipids (typically between C26 and C30) that are resistant to saponification and can be classified as triterpenes. 

It has been proposed that acrolein can be transformed metabolically into acrylic acid, which may be incorporated into amino acids, fatty acids, and sterol. Flowever, specific biomarkers of effect for acrolein have not been identified. Studies regarding identification of these biomarkers would be useful. 

Li, W., J. Dagaut, and A. Saliot. 1995. The application of sterol biomarkers to the study of sources of particulate organic matter in the Solo River system and the Seraya River, Java, Indonesia. Biogeochemistry 31 139-154. 

The organic chemistry of this study focused on some of the most coimnon sterols in soils, i.e., cholesterol, 24-ethylcoprostanol, stigmasterol, campesterol, and b-sitosterol. 24-Ethylcoprostanol has been used as biomarker for (nonhuman) herbivore fecal matter. Results of the BC/MS analysis of one of the sediment samples is shown in Fig. 6.26 and the presence of these sterols clearly identified. This sample is taken from the stable area and clearly shows the presence of coprostanol and 24-ethylcoprostanol indicating enrichment by fecal material from herbivores. 

In this section two of the most intensively studied classes of biomarkers are examined fatty acids and sterols.The units from which polysaccharides and lignins are formed (i.e. monosaccharides and phenolic compounds, respectively) can be analysed as readily as biomarkers and the source-related information that their distributions can convey is also considered. 

When did LUCA give rise to her diverse offspring Cells resembling modern prokaryotes date back 3.5 billion years, to the stromatolites in south-western Australia, as described in Chapter 3. The first signs of eukaryotic cells, the biomarkers of membrane sterols, date to about 2.7 billion years ago. The first unequivocal eukaryotic fossils are found... 

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