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An effective approach for the detection of coated DNA in natural seawater is discussed. Eutrophic seawater samples were derived from Tokyo Bay and subjected to enzymatic differentiation of free and coated DNA materials, DNA size fractionation and immunochemical-potentiometric DNA quantification. DNA molcular size was also estimated. The dominance of coated DNA in eutrophic seawater was established.

Pore water needs to be extracted from rocks with low permeabilities to allow the major ion concentrations in the pore water to be estimated. Compressing a rock is the most widely used method of extracting the pore water. However, ion concentrations have been found to change during compression in previous studies, and the mechanisms involved in such ion concentration changes have not yet been fully assessed. In this study, two natural rocks and four artificially prepared samples were compressed, and changes in the chloride ion (Cl−) concentrations as the compression pressure increased were investigated. Mechanisms that could have caused the changes observed were then assessed. The Cl− concentrations in squeezed water decreased as the pressure increased if the sample contained a significant amount of smectite. The strong dependence of Cl− concentration on the amount of smectite indicated that smectite played an important role in decreasing the Cl− concentration. The dilution of the pore water with interlayer water from the smectite appeared to be the dominant mechanism involved in the decrease in Cl− concentration found in a Kunigel-V1 sample, because dilution of the pore water with interlayer water quantitatively explained the decrease in the Cl− concentration. The filter effect caused by the anion exclusion effect did not appear to be a dominant mechanisms in our case. However, Cl− concentration decrease found in natural rocks could not be fully explained by dilution with interlayer water, so other mechanisms must be involved the phenomenon in natural rocks. [ABSTRACT FROM AUTHOR]

A marine microbe (strain SR21) from the coral reef area of the Yap Islands was isolated by a screening test for polyunsaturated fatty acids and was found to accumulate lipid that contained 22:5n-6 docosapentaenoic acid (DPA) as well as 22:6n-3 docosahexaenoic acid (DHA). Strain SR21 was identified as genus Schizochytrium in Labyrinthulomycota, owing to its ultrastructural character and life cycle, which is composed of vegetative cell, zoosporangium, and zoospore stages. After cultural optimization, both in flask and fermenter, the highest DHA and DPA productivities of 2.0 and 0.44 g/L per day, respectively, were obtained in a medium of 60 g/L glucose and corn steep liquor/ammonium sulfate in a half salt concentration of seawater in fermenter culture at 28°C and pH 4. This productivity was almost twice that obtained with flask culture, indicating its high resistance to mechanical stirring. The lipid extracted from the cell was about 50% of the dry cell weight and was composed of 93% triacylglycerol (TG). DHA content of the lipid was 34% of total fatty acids. The TG profile was simple, and the content of the most dominant TG, 1,3-dipalmitoyl-2-DHA-TG, was 27%. TG that contained DHA and n-6-DPA amounted to 57 and 17%, respectively, of total TG molecules. Strain SR21 was revealed to be an excellent source of microbial DHA and n-6 DPA. [ABSTRACT FROM AUTHOR]