PubMed · 9419936
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C Stillman-Lowe. 1997-11-22. Between two paradigms.. https://doi.org/10.1038/sj.bdj.4809505
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The differential display of the mRNA technique for eukaryotes is fruitful in identifying genes with altered transcription rates caused by exogenous or endogenous stimuli. Prokaryotic analogues of the method using arbitrary oligonucleotides may reach a complete statistical genome coverage. Thus a genome-wide mass screening for transcriptionally regulated sequences will be possible. However, the primer sets have to be optimized for a given species to result in maximum band yields. Hence the construction of primers requires the calculation of oligonucleotide frequency distributions from known coding regions to choose sequences with frequent occurrence in the bacterial genome. After completion of many whole genome sequencing projects, differentially regulated cDNA sequences are readily identified by sequence comparisons.
Glutathione S-transferase activity of both the microsomal and soluble fractions was determined in a variety of aquatic macrophytes. The examined enzyme extract was prepared from a combination of leaves and shoots. Four different model substrates were used. The highest conjugation rate was obtained for 1-iodo-2,4-dinitrobenzene, followed by 1-chloro-2,4-dinitrobenzene, p-nitrobenzoyl chloride, and 1,2-dichloro-4-nitrobenzene. Comparison of several samples of Nuphar lutea L. from two different lake areas revealed increased glutathione S-transferase activity in plants from the site contaminated with polyaromatic hydrocarbons.
Helicobacter pylori infection is a risk factor for gastric cancer and most epidemiological studies have estimated a relative risk associated with infection in the order of two to four-fold. There is interest in the extent to which this risk estimate might vary between different populations especially as several populations have been identified with low rates of gastric cancer despite a high infection prevalence. Methodological differences between studies make it difficult to compare the results of retrospective case-control studies to quantify the variation in risk, but prospective studies indicate that there may be a six-fold variation in risk between different populations. It is likely that genetic and/or environmental co-factors are important in modifying the risk associated with H. pylori infection but there are few studies that have fully investigated the role of such co-factors.