Age and growth of yellowstriped butterfish, <Emphasis Type="Italic">Labracoglossa argentiventris</Emphasis>, around Izu Oshima Island

ABSTRACT:   Age and growth of the yellowstriped butterfish, Labracoglossa argentiventris , around Izu Oshima Island were studied using a total of 1450 fish. Age was determined by counting the edge of the opaque zones as a ring mark on sectioned sagittal otoliths. Formation of the first ring was observed during spring or summer, corresponding to 1.5 years after hatching. Thereafter, one ring was formed each year in the same season as the previous year. The growth of the butterfish was rapid until 2 years of age. The maximum likelihood method was applied to the age and length data for estimating parameters in von Bertalanffy, Gompertz, and Logistic growth models. The selected model, based on the Akaike Information Criterion, was the von Bertalanffy growth model, which indicated differential asymptotic length and variance by sex.     

The dietary effects of a fermented vegetable product on glutathione peroxidase activity and lipid peroxidation of Japanese flounder Paralichthys olivaceus

ABSTRACT:   To study the dietary effects of fermented vegetable product (FVP) on the protection against lipid peroxidation of various tissues in Japanese flounder, Paralichthys olivaceus . The fish were fed on experimental diets with or without FVP for 4 weeks. The glutathione concentrations in serum or liver had a tendency to increase on FVP-feeding fish. The FVP-feeding fish showed higher glutathione peroxidase (GPx) activity of liver than the control fish, and the GPx activity was increased by the administration of 6 mg/kg body weight/day FVP ( P  < 0.05). Conversely, fish fed on FVP containing diets exhibited significantly ( P  < 0.05) lower lipid peroxidants of serum and liver than the control fish. The FVP is suggested to suppress lipid peroxidation in the administrated fish, which led to enhancement of antioxidant effect against cultured fish.     

The ex vivo effects of eyestalk peptides on ovarian vitellogenin gene expression in the kuruma prawn Marsupenaeus japonicus

Seven major peptides belonging to the crustacean hyperglycemic hormone family were purified from the sinus gland located in the eyestalk of the kuruma prawn Marsupenaeus japonicus, and their effects on vitellogenin gene expression were examined using the ex vivo ovary incubation system. Six molecular species of crustacean hyperglycemic hormone, Pej-SGP-I, -II, -III, -V, VI, and VII, displayed significant inhibitory effects on vg expression with almost the same efficacies, whereas Pej-SGP-IV (known as molt-inhibiting hormone) did not. Two chromatophorotropic peptides, red pigment-concentrating hormone and pigment-dispersing hormone, which were also present in the sinus glands, did not have a clear effect on the gene expression levels in this incubation system. These results suggest that the six crustacean hyperglycemic hormones are potentially capable of acting as vitellogenesis-inhibiting hormones in M. japonicus.     

Effect of ovary lipid from Skipjack tuna (Katsuwonus pelamis) on brain monoamines in rats

In our previous experiments with rats, ovary lipid from Skipjack Tuna (Katsuwonus pelamis) (OLS) was shown to have a mitigating effect on anxiety and/or fear in elevated T-maze tests. This suggests that OLS has some effect on the central nervous system (CNS) of rats. Thus, we performed experiments to examine the status of CNS in rats given OLS. The effect of OLS on chronic stress was also examined at the same time. The feed for control rats used oil and fat that have the same energy percentages for n-6 and n-3 fatty acids and the same n-6/n-3 ratio as OLS. As a result, rats given OLS for 28 days had lower serotonin levels in various brain areas regardless of stress application, showing that OLS affected the serotonin nervous system. From this, it was inferred that the ability of OLS to mitigate anxiety and/or fear resulted from its action on CNS, especially the serotonin nervous system. Substances other than the essential fatty acids may have been responsible for the action of OLS on monoamines and the metabolites. The effect of OLS on CNS, especially the serotonin nervous system, suggests that OLS may suppress anxiety.