Naupliar copepod concentrations in the spawning grounds of Japanese sardine, Sardinops melanostictus, along the Kuroshio Current

Naupliar copepods were distributed at similar concentrations over the waters inshore and offshore of the Kuroshio Current off central Japan in early spring 1993 and 1994, overlapping with the distribution of early feeding larvae of Sardinops melanostictus . Although N, P, Si and chlorophyll a concentrations were higher in the waters inshore of the Kuroshio axis than in the offshore waters, the mean concentrations of nauplii were not statistically different between the two waters. Food availability for larval S. melanostictus did not seem to be different between the two waters in terms of the mean food concentrations. Using the critical food concentration (>9 nauplii L^–1) for 25% survival during 3 days after first feeding derived from a rearing experiment, percentages in number of stations or water samples with nauplii concentrations >9 nauplii L^–1 were higher in the inshore waters than in the offshore waters in both years examined. Considering that fish larvae may depend on small-scale patchiness of food for their survival, the inshore waters seemed to be more favourable for first-feeding larvae than the offshore waters.     

Evidence of a local spawning site of marine eels along northeastern Japan, based on the distribution of small leptocephali

Evidence of recent spawning by several species of marine eels of the families Congridae, Ophichthidae, and Nettastomatidae was found over the continental shelf along the coast of northeastern Japan in October 2003. Sixty‐three leptocephali of at least three taxa that ranged from 3.8 to 12.3 mm total length were collected in a relatively small area, just to the south of Cape Shioya, primarily over the 100‐and 200‐m‐depth contours. The leptocephali of Gnathophis nystromi nystromi were the most abundant, followed by those of G. nystromi ginanago. This spawning area is located in an area that appeared to include water originating from the Tsugaru Warm Current and is further south than the typical latitude of the cold water of the Oyashio First Intrusion. These findings suggest that some species of marine eels may not migrate past the slope to spawn, and that the oceanographic features of the region may provide favorable conditions for the growth and retention of leptocephali in the area to the south of Cape Shioya.     

Development of a sandwich enzyme-linked immunosorbent assay (ELISA) to quantify γ-glutamyl-carboxylated clotting factor IX and assess redox susceptibility of anticoagulant chemicals

Anticoagulant chemicals (ACCs) such as warfarin are widely used in medical applications as well as for their rodenticide properties. Their efficacy is greatly influenced by polymorphisms in the gene encoding vitamin K epoxide reductase (VKOR). Evaluation of the activity of ACCs toward VKOR variants is essential to determine their proper use. Presently, this is achieved by co-expressing VKOR of Rattus Norvegicus and human clotting factor IX in cultured cells and measuring inhibition of vitamin K-dependent gamma-glutamyl carboxylation of factor IX (glaFIX) activity. However, glaFIX has only been quantified using indirect methods like blood coagulation assays. We have developed a sandwich enzyme-linked immunosorbent assay using a glaFIX-specific antibody to quantify glaFIX and used this to analyze inhibition of VKOR activity by warfarin.     

Age-related accumulation of persistent organic chemicals in captive king penguins (Aptenodytes patagonicus)

Persistent organic chemicals are non-biodegradable in nature and have a tendency to bioaccumulate in the top organisms of the food chain. We measured persistent organic chemicals, including polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (DDE), and benzotriazole-based ultraviolet stabilizers (UV-BTs), in the serum of captive king penguins (Aptenodytes patagonicus) using gas chromatography with an electron capture detector and mass spectrometry to examine their age-related accumulation. PCBs, DDE, UV-PS, and UV-9 were detected in the blood of captive king penguins, and the concentrations of total PCBs, DDE, and UV-9 were positively correlated with age. These results suggest that there is a similar age-related accumulation of persistent organic chemicals in marine birds in the wild, and that older individuals are at a higher risk of contamination.     

Relationship between milk production and plasma concentrations of oxidative stress markers during hot season in primiparous cows

Oxidative stress markers, ascorbic acid, and sulfhydryl (SH) residue concentration in primiparous cows' plasma and their relationship to milking performance during hot seasons were investigated. The rectal temperature of cows correlated negatively with SH residue (r = −0.38, n  = 38, P  < 0.05) and ascorbic acid (r = −0.34, P  < 0.05) concentrations in the cows' plasma. The group with a higher concentration of ascorbic acid over the mean value produced significantly more milk ( P  < 0.05) than did the group with a lower ascorbic acid concentration. Although the cows' milk production showed a positive correlation with ascorbic acid concentration in plasma (r = 0.47, P  < 0.05), the relation of SH residue concentration to milk yield was not constant. The plasma SH residue concentration during the hot season correlated positively with milk protein % (r = 0.38, P  < 0.05), lactose % (r = 0.35, P  < 0.05), and solid-non-fat (SNF) % (r = 0.47, P  < 0.05), respectively, but not with fat %. On the other hand, ascorbic acid concentration in plasma showed negative correlations with milk fat % (r = −0.34, P  < 0.05) and protein % (r = −0.49, P  < 0.05), but correlated positively with lactose % (r = 0.52, P  < 0.05). The produced amount (g/day) of milk protein (r = 0.42, P  < 0.05), lactose (r = 0.61, P  < 0.05), and SNF (r = 0.56, P  < 0.05) showed positive correlations with ascorbic acid concentration in plasma.     

Age-related changes in leukocytes and T cell subsets in peripheral blood of Japanese Black cattle

It is well known that the immune system changes with age during development and maturation in Holstein cattle. But age-related changes in leukocytes and T cell subsets in peripheral blood of Japanese Black cattle still remain unclear. The aim of the present study was to investigate comparative changes of leukocytes (granulocytes, monocytes, B cells and T cells) and T cell subsets (CD4⁺, CD8⁺, γδ, CD8⁺γδ and WC1⁺γδ T cells) in Japanese Black cattle aged 0.5, 1, 2, 6, 18 and 36–41 (adult) months on flow cytometry using specific monoclonal antibodies for the cell surface markers. T cell proportion was approximately 40% in 2-month-old cattle and decreased to 20.6% in adults. In contrast, B cell proportion significantly increased from 7.4% to 28.2% with age. In T cell subsets the percentage of CD4⁺ T cells significantly increased from 40.5% to 60%, but that of WC1⁺γδ T cell subset significantly decreased with age. The percentages of CD8⁺ and CD8⁺γδ T cells did not change. The present study details the proportional changes in leukocyte and T cell subsets with age in the peripheral blood of Japanese Black cattle and these findings are similar to those described for Holstein cattle.     

Microbial biomass and nitrogen transformations in surface soils strongly acidified by volcanic hydrogen sulfide deposition in Osorezan, Japan

Volcanic acidification has created unique ecosystems that have had to adapt to the acidic environments in volcanic regions. To characterize the primary microbial properties of strongly acidified soils in such environments, we investigated microbial biomass, nitrogen transformations and other relevant chemical properties in the surface soils of solfatara and forests from Osorezan, a typical volcanic region in Japan, and compared the results to common Japanese forest soils. Soil microbial biomass C (MBC) and N (MBN) were determined using the chloroform fumigation–extraction method. Potential net N mineralization and net nitrification were measured in aerobic laboratory incubations. Long-term acidification in the Osorezan soils by volcanic hydrogen sulfide deposition caused low soil pH (3.0–3.8), base cation deficiency and increased concentrations of toxic ions such as Al³⁺. The proportions of MBC to total carbon (MBC/TC ratio) and MBN to total nitrogen (MBN/TN ratio) were lower than those in common Japanese forest soils. The extreme acidic conditions may have inhibited microbial survival in the Osorezan acid soils. Net N mineralization occurred at rates comparable to those in common Cryptomeria japonica forest soils, probably because of the presence of acid-tolerant soil microorganisms. Net nitrification was completely inhibited and autotrophic ammonia oxidizers were not detected by the MPN method. The inhibition of nitrification prevents nitrogen leaching from the soils, thus maintaining a nitrogen cycle in the volcanic acid region in which     (and NH₃) is recycled among microorganisms and plants.