No abstract

Apparent and true availabilities of amino acids from white fish meal (FM), defatted soybean meal (SBM), malt protein flour (MPF), corn gluten meal (CGM), extruded SBM (ExSBM), and extruded MPF (ExMPF), were determined by an indirect method for fingerling rainbow trout Oncorhynchus mykiss, common carp Cyprinus carpio, and red sea bream Pagrus major.Apparent protein digestibilities (APD) of FM (89 to 94%), SBM (90 to 93%), and MPF (81 to 84%) were almost identical in the three species tested. However, the APD of CGM in carp (76%) and bream (79%) were lower than that in trout (95%). Individual apparent amino acid availabilities (AAAA) approximated the APD. The APD of ExSBM and ExMPF were two to four percent higher than the unextruded SBM and MPF, respectively, without any negative influences on individual AAAA. This finding suggests that the extrusion processing is an effective method to improve availabili ties of amino acids in SBM and MPF. On the other hand, relatively large differences were recognized be tween the true amino acid availabilities (TAAA) and the AAAA among certain amino acids. Thus, de termination of TAAA may be necessary for more accurate and economical feed formulation.

No abstract

Female sea urchins store the major yolk protein (MYP) in ovarian nutritive phagocytes before vitellogenesis. Using immunological procedures, we detected MYP in the testicular nutritive phagocytes of Pseudocentrotus depressus, the red sea urchin, and then compared the distribution of MYP between sexes during gametogenesis. MYP was purified from unfertilized eggs by ion exchange chromatography (Q Sepharose) and gel filtration (Superdex 200), and an antiserum (anti-MYP) was raised against MYP. Immunoblot analysis demonstrated that immature testes, as well as ovaries, contained a large quantity of MYP. Immunohistochemistry showed that MYP was distributed in the nutritive phagocytes occupying the follicular lumen in both males and females. In both sexes, as gametogenesis proceeded, the nutritive phagocytes degenerated and the gonadal lumen filled with gametes. MYP accumulated in ripe ova as a yolk protein in the mature ovary. In contrast, MYP was not detected in mature testes, because stored spermatozoa did not react with anti-MYP. We conclude that in male P. depressus, MYP is stored in the testicular nutritive phagocytes and utilized as the nutrient source for spermatogenesis.

SUMMARY Both male and female sea urchins accumulate the major yolk protein (MYP;the most abundant yolk granule protein in sea urchin eggs) in the nutritive phagocytes of immature gonads before gametogenesis. In this study,quantitative changes in MYP as well as in other biochemical components in the ovary and testis were examined in the course of gametogenesis in Pseudocentrotus depressus. Before gametogenesis, both the ovary and testis contained large quantities of proteins, lipids and polysaccharides. MYP reached about 80% of total protein in both sexes. In the testis, MYP decreased rapidly as spermatogenesis proceeded, and the fully mature testis contained little MYP; the levels of lipids and polysaccharides also decreased. In contrast, the levels of nucleic acids and proteins other than MYP increased markedly. In the ovary, MYP decreased gradually as oogenesis proceeded, and the fully mature ovary contained less than half of the initial amount of MYP. Polysaccharides also decreased, whereas proteins other than MYP increased. These results, taken together with those from other studies, suggest that MYP serves as a protein reserve that accumulates before gametogenesis and is used as material for synthesizing new substances constituting gametes in both male and female sea urchins.