Utilization of free amino acids, yolk proteins and lipids in developing eggs and yolk-sac larvae of walleye pollock Theragra chalcogramma

ABSTRACT:   To elucidate the utilization of the major yolk nutrient stocks in eggs and larvae of walleye pollock Theragra chalcogramma , the contents of free amino acids (FAA), the major yolk protein (180 kDa lipovitellin originated from vitellogenin B in ovulated eggs: oLv B), and lipids were measured. Most eggs hatched 18 days after fertilization at 5°C, and all larvae absorbed almost all their yolk mass by 28 days. The total FAA content showed no change during the first 6 days, and then decreased to 28% of the initial level by 18 days. The oLv B contents, measured by an enzyme-linked immunosorbent assay using a specific antiserum against oLv B, gradually decreased from 6 to 18 days, followed by a rapid decline. The content of phospholipids (PL) and triacylglycerols (TG) showed no marked change until hatching, and then decreased until disappearance of yolk sac. From these results, it is proposed that there are two main periods for nutrient utilization in embryos and larvae of walleye pollock. In the first period, FAA was mainly utilized until 18 days after fertilization. Active utilization of oLv B and lipids (PL and TG) instead of FAA occurred during the second period from 18 to 28 days.     

Deduced primary structures of three types of vitellogenin in mosquitofish (Gambusia affinis), a viviparous fish

Three distinct forms of vitellogenin (Vg), 600 kDa VgA and VgB and 400 kDa Vg, were discovered biochemically in estrogen treated female plasma. By sequencing of the three Vg cDNAs, the VgA and VgB were recognized as complete Vgs having all yolk protein (YP) domains, and the 400 kDa Vg was thought to be phosvitinless (Pvl) Vg lacking phosvitin (Pv) domain.     

Life history and ecology of the glowbelly <Emphasis Type="Italic">Acropoma japonicum</Emphasis> in the Uwa Sea,Japan

ABSTRACT:   The life history and ecology of the glowbelly Acropoma japonicum a commercially important fishery resource, were investigated in the Uwa Sea, Japan. Newly settled juveniles (0⁺) appeared at the end of the breeding season and reached maturity in the next season, i.e. when they became yearlings (1⁺). The yearlings made a gametic effort comparable to that of older fish. During the breeding season, the somatic conditions were more deteriorated for males than for females. That the deterioration of male somatic conditions was not attributable to a sexual difference in energy gain from feeding suggests that the males incurred higher energetic costs of reproduction despite their relatively low gonadosomatic indices. Such an energy depletion may increase the mortality risk, resulting in female-biased sex ratios in the older age classes. Most of the 1⁺ fish disappeared in winter following their first breeding. For A. japonicum , the observed precocity and short life span is notable because it is a higher consumer that is generally expected to show later maturation and longer life. As possible explanations for their disappearances, predation and postbreeding emaciation were less likely. While fishing is one of the most influential factors, the possibility of age-specific migration toward deeper waters remains to be examined.     

Taurine transporter from the giant Pacific oyster <Emphasis Type="Italic">Crassostrea gigas</Emphasis>: function and expression in response to hyper- and hypo-osmotic stress

ABSTRACT:   Taurine is the primary osmolyte in marine molluscs, whose cellular osmo-conforming process is vital for environmental adaptation because of a lack of osmotic homeostasis. Here, cDNA cloning and expression, and functional analyses of taurine transporter (TAUT) from the giant Pacific oyster are reported on. The deduced amino-acid sequence of oyster TAUT (oyTAUT) showed 47–51% identity to those of vertebrate TAUT, whereas identity among the vertebrates is 78–95%. Functional analysis of oyTAUT expressed in Xenopus oocytes revealed that oyTAUT has a lower affinity and specificity for taurine and a requirement for higher NaCl concentration, compared with vertebrate TAUT. Taken together with similar functional properties of TAUT from mussel, indicated by our previous study, it is possible that these functional features reflect the internal environment of the molluscs (i.e. higher taurine and NaCl concentrations). Oyster taurine transporter mRNA expression was induced by not only hyper-osmotic stress, similar to other TAUT, but also hypo-osmotic stress. It is speculated that the expression in response to hypo-osmotic stress was induced by a substantial decrease in tissue taurine content following the decrease in the internal osmolality.     

Is experience on a farm an effective approach to understanding animal products and the management of dairy farming?

The understanding of animal products and dairy farming is important for the promotion of dairy farming. Thus, to examine the effects of farm experience on the understanding of animal products and the management of dairy farming, the interaction between students and dairy cows was investigated in groups of first‐year veterinary nursing students in 2011 and 2012 (n = 201). These students included 181 women and 20 men. Nine items about dairy cows were presented in a questionnaire. The survey was performed before and after praxis on the educational farm attached to the authors' university. After praxis on the farm, increases occurred in the number of positive responses to the items involving the price of milk, dairy farming and the taste of milk. For these items, a significant difference (P < 0.05) was found between the scores obtained before and after training. The results of the study suggested that farm experience is useful for improving the understanding of animal products and dairy farming.     

Oocyte growth in temperate basses: multiple forms of vitellogenin and their receptor

A full-length cDNA encoding a vitellogenin (Vg) receptor (VgR) was isolated and sequenced from a white perch, Morone americana, ovarian cDNA library. The perch expresses a single VgR that is structurally classified as an LR8 type (without an 0-linked sugar domain) and appears to be the only species observed to possess no splice variant of the receptor. We proposed a hypothetical model for ovarian lipid transfer in Morone species, one in which the `single VgR' transports Vg and other lipoproteins via a selective endocytotic pathway based on ligand affinity, in conjunction with a lipase-mediated pathway of fatty acid transport.     

Filtering method for obtaining stock indices by shark species from species-combined logbook data in tuna longline fisheries

ABSTRACT:   A method of filtering logbook data to obtain estimates of catch per unit effort (CPUE) for sharks has been proposed which simultaneously addresses the issues of under-reporting and the lack of species-specific catch records in historical data. Logbook catch data from vessels with high shark reporting rates are used to represent catch rates for the abundant blue shark Prionace glauca and low reporting vessels' data are used for the main commercially valuable species, the shortfin mako Isurus oxyrinchus . Logbook reporting rate filter (RRF) levels are evaluated through analytical and model-based comparisons to species-specific logbook records available since 1994 and shipboard observer data. At the high reporting rates, the ≥ 80% filter avoids large numbers of false zeros and provides the best fit to observer data for blue shark. At the low reporting rates, the ≤ 40% filter best matches the observer data for makos, but this filter level includes large numbers of false zeros and sharks of other species. The ≤ 20% filter produces a dataset that is better targeted to mako catches but considerably under-estimates CPUE relative to observer records. For these reasons, other means of estimating mako catch rates are suggested for further research.