Establishment of Supporting System for evaluating Biological Environments based on Protistan DNA nucleotide sequences

点击翻译按钮获取中文摘要

In order to establish a support system for assessing marine biological environments, a genetic database of protistan species, which are commonly used as environmental proxies, was constructed for ribosomal DNA sequences. DNA analyses. were carried out for LSU, SSU and ITS sequence regions of ribosomal DNA. Relationships between species and ambient environments were compiled, both from publications and unpublished theses of Shizuoka University, to provide ecological or morphological constraints for the database.Samples for analyses were collected from seven innerbays from north to south along the Japanese Islands. Six species of benthic foraminifera (Protista) were selected for analysis. All are commonly used as proxies for dysaerobic environment or eutrophicated condition within the inner bay environment.The database was constructed for DNA sequences of these species. Sequence data for each species were listed, together with intraspecific and/or interspecific divergences, as a dataset. … More Physiological, ecological and morphological responses to ambient environmental changes were compiled to characterize each species as a specific environmental proxy. For instance, Trochammina hadai Uchio, which dwells in eutrophic environments of brackish bays, changes its test morphology in relation to the dissolved oxygen concentration at the sediment-water interface. This species reproduces at a water temperature of 10〜18 ℃, salinity of 25〜30 ‰, and dissolved oxygen concentration of 6〜8 ml/L. Sequence data for this species are sufficiently unique to discriminate from similar taxa. LSU rDNA sequences show only 0.1% difference between distributional areas. The ITS region, where substitution occurs very frequent, shows 2.0% of sequence differences.Sequence divergence tends to be smaller in highly polluted area of the sea, where heavy deposition of organic carbon takes place, than in less-polluted area. This tendency can be used as a good proxy for assessing precise environmental changes in response to pollution. Less