Search

Hemicentrotus pulcherrimus is usually consumed in summer when the ovaries and testes are immature and tasty, and is not utilized from autumn to spring as a bitter compound, pulcherrimine accumulates in the ovaries. However, in the northern distribution edge (Tohoku and Hokkaido), it is not consumed because the ovaries are bitter nearly all year. Our previous studies suggested that the short palatable season in northern H. pulcherrimus is caused by a lower seawater temperature. To test this hypothesis, we reared H. pulcherrimus collected in Hokkaido at manipulated temperatures. Higher temperatures than the natural temperature at the collection site from August to March delayed gametogenesis and pulcherrimine accumulation, which usually begins in autumn. Temperature elevation during the spawning season (April) advanced the transition of mature ovaries to immature ovaries and led to the disappearance of the remaining pulcherrimine. Seawater temperature estimated using an ocean forecast system revealed that the warmer season, when the temperature exceeds 20 °C, is shorter where H. pulcherrimus is not consumed. We believe that the short palatable season of H. pulcherrimus in the northern edge of the distribution is due to the short summer season. Such H. pulcherrimus, however, can be improved by cultivation for several months at elevated temperatures. [ABSTRACT FROM AUTHOR]

The major yolk protein in sea urchins is a transferrin-like protein. In this report, a new component was detected in gonad extracts of Strongylocentrotus intermedius and Mesocentrotus nudus, which cross-reacts with antiserum against egg yolk proteins. We tentatively named them egg yolk-related proteins siYRP and mnYRP. The siYRP was purified from testis of S. intermedius by ammonium sulfate fractionation, anion exchange chromatography, affinity chromatography and gel filtration. Purified siYRP was > 900 kDa in size. The siYRP purified on SDS-PAGE under reducing conditions gave seven bands, corresponding to 93, 213 and > 250 kDa. Purified mnYRP displayed similar structural characteristics as siYRP. Purified siYRP and mnYRP were identified by tandem mass spectrometry and renamed as siVitellogenin (Vtg)-like and mnVtg-like proteins, respectively. Both Vtg-like proteins were confirmed to be lipoglycoproteins by staining with Sudan black and periodic acid-Schiff. A specific antiserum against the siVtg-like protein was raised in rabbit. Antiserum against the siVtg-like protein immunostained siVtg-like and mnVtg-like proteins. Immunochemical methods using the antiserum revealed that siVtg-like and mnVtg-like proteins were present in the ovary, testis and unfertilized eggs of both species. These results indicated that Vtg-like proteins have important physiological functions for gonadal growth and gametogenesis in sea urchins. [ABSTRACT FROM AUTHOR]

Coincident with the population increase in the 1990s, egg and larva distributional area of the Pacific stock of Japanese anchovy Engraulis japonicus expanded from the warm Kuroshio waters toward the cold Oyashio waters off northern Japan. To understand how Japanese anchovy expanded its spawning and nursery grounds, egg and larva distributions and larval growth rates were investigated in relation to temperature and flow fields in the Pacific waters off northern Japan (Pacific North, PN) in summer. Anchovy eggs occurred in the Oyashio waters (≤5 °C at a 100-m depth) warmer than or equal to 15.9 °C in sea surface temperature (SST) which is close to the known lower limit of spawning temperature. Eggs and larvae would be transported southwestward to the warmer coastal and offshore waters by the currents dominated in the study area. Temperature experienced by anchovy eggs and larvae in the northern subarctic waters was almost the same as that in the southern spawning ground in spring. Larval growth rates in the study area were comparable to the previous studies in the southern nursery areas. Thus, the subarctic PN waters would function as spawning and nursery grounds of E. japonicus in the decades of high stock abundance. [ABSTRACT FROM AUTHOR]

Eight Southeast Asian freshwater puffers- Tetraodon biocellatus, T. cochinchinensis, T. cutcutia, T. palembangensis, T. turgidus, Carinotetraodon irrubesco, C. lorteti, and C. travancoricus-spawned in captivity at the Shimonoseki Marine Science Museum Aquarium, and the larvae were reared for more than 180 days. Tetraodon cochinchinensis, T. cutcutia, T. palembangensis, and T. turgidus spawned large eggs in batches and protected them; Carinotetraodon travancoricus spawned and protected a few eggs, larger than those of congeners; and T. biocellatus, C. irrubesco, and C. lorteti spawned smaller eggs that were scattered and unprotected. Larval growth was faster in T. cochinchinensis, T. cutcutia, T. palembangensis, and T. turgidus and slower in T. biocellatus, C. irrubesco, C. lorteti, and C. travancoricus. [ABSTRACT FROM AUTHOR]

The embryonic development and morphology of eggs and newly hatched larvae of the Pacific herring Clupea pallasii were described using laboratory-reared specimens originating from the Miyako Bay stock. The eggs were almost spherical in shape, 1.33-1.46 mm (mean: 1.38 mm) in diameter, and had a thick adherent chorion. They had a segmented pale yellow yolk, no oil globule, and a relatively wide perivitelline space. A subgerminal cavity was observed during the gastrula period, whereas the blastocoel did not appear. Mass hatching occurred by 271 h 45 min after fertilization, and the newly hatched larvae were 7.1-7.7 mm (mean: 7.5 mm) in total length with 53-56 myomeres at 9.6°C. The embryonic development of Pacific herring was substantially similar to that of zebrafish Danio rerio, American shad Alosa sapidissima, as well as Atlantic herring Clupea harengus, and generally followed the basic developmental pattern of teleosts. However, Pacific herring larvae hatched at a more developed stage than some other clupeoids, such as Japanese sardine Sardinops melanostictus, and the progressed developmental stage at hatching could be interpreted as an advanced adaptation. [ABSTRACT FROM AUTHOR]

Changes in lipid content and fatty acid composition of muscle, liver and ovary of captive-reared and wild silver Japanese eel Anguilla japonica were examined during artificial maturation induced by salmon pituitary homogenate (SPH) injections. Although the relative levels of n-3 and n-6 highly unsaturated fatty acids (HUFA) in liver and ovary were higher than in muscle in both captive and wild silver eels before SPH injection, these tended to decrease with maturation. The relative levels of n-6 HUFA in muscle, liver, ovary and eggs of wild silver eels were remarkably higher than those in captive eels. Therefore, we attempted to alter the ratio of n-6 HUFA in eggs by feeding eels a diet supplemented with linoleic acid-rich plant oil. Although the percentage of n-6 polyunsaturated fatty acids to total fatty acids in eggs of eels fed the supplemented diet was similar to wild silver eels, the percentage of n-6 HUFA remained remarkably lower than in wild silver eels. Hence, it appears that the supplemented diet affected the fatty acid composition of eggs, but did not result in much conversion of linoleic acid to its higher homologs in eels. [ABSTRACT FROM AUTHOR]

ABSTRACT: Effects of prolonged retention time of ovulated eggs in the parental coelom on fertilization success were studied in rainbow trout Oncorhynchus mykiss using cryopreserved sperm with a uniform fertilizing ability. Proportions of successful fertilization, eyed eggs and hatched alevins were examined at different time periods up to a retention time of 14 days beyond the ordinary stripping time, and were compared with eggs incubated in artificial coelomic fluids (ACF). Eggs that were retained longer in the coelom showed gradual decreases in all the proportions of successful fertilization, eyed eggs and hatched alevins. The progress of cleavage after fertilization slowed with prolonged retention times. Eggs incubated in ACF lost their fertilizing ability much sooner than those retained in the coelom. The hatching rate of eggs retained for 2 weeks in coelom was 36%, while it was 1% in those eggs incubated for 4 days in ACF. Thus, eggs retained in the coelom showed higher fertilization success than those incubated in ACF. [ABSTRACT FROM AUTHOR]

ABSTRACT: A trypsin inhibitor was purified from the egg of skipjack tuna Katsuwonus pelamis by ammonium sulfate precipitation, gel filtration on a Sephadex G-100 column, ion-exchange chromatography on diethylaminoethyl-Sephacel, rechromatography on a Sephadex G-100 column and reversed-phase high-performance liquid chromatography on a C18 column. The molecular mass of the purified trypsin inhibitor was approximately 78 kDa as estimated by gel filtration and 39 kDa by sodium dodecylsulfate polyacrylamide gel electrophoresis. The purified trypsin inhibitor was stable in the pH range from 4.0 to 10.0 and at temperatures below 40°C. The purified inhibitor was rich in Gly, Glu, Ser, Asp and Lys, but poor in Cys, Tyr, Phe, Ile and His. In addition, the activity of the purified trypsin inhibitor was increased in the presence of metal ions such as K+ , Na+ , Mg2+ and Ca2+ . [ABSTRACT FROM AUTHOR]

ABSTRACT: Development of embryos and larvae in the common Japanese conger Conger myriaster was observed after artificial fertilization. Eggs were obtained from females matured artificially by hormone injections and milt was obtained from males matured naturally. Fertilized eggs were kept in seawater at 12–14°C. The first cleavage occurred at 4 h, epiboly began at 24 h, the embryonic body was formed at 38 h and hatching occurred at 84 h after insemination. Newly hatched larvae were approximately 2.5 mm (total length) and similar to those of Anguilla japonica in terms of external features. The mouth and anus opened on the 7th day after hatching. Pigments began to appear at the tip of the tail on the 10th day. The total length of the larvae reached approximately 8 mm on the 11th day. Eye pigmentation began on the 14th day. One larva lived for 19 days without food. [ABSTRACT FROM AUTHOR]

ABSTRACT: The present study was conducted to investigate the effects of dietary vitamin A on reproduction and egg quality in Japanese flounder Paralichthys olivaceus. Broodstock were fed experimental pellets containing two levels of vitamin A [11 × 103 IU/100 g (control diet; CD), 337 × 103 IU/100 g (experimental diet; ED)] for approximately 2 months before spawning and during the spawning period. Two groups of five females (average weight 1.4 kg) and 10 males (average weight 0.7 kg) were randomly allocated to two 30 m3 indoor tanks. Total egg production of the CD group was slightly higher than the ED group. Percentage of buoyant eggs and hatching rate of the ED group were significantly higher than the CD. In other egg quality parameters, such as percentage abnormal larvae and starvation tolerance of larvae, no notable difference was found between these two groups. At the end of the experiment, the skin color of broodstock in the ED group was darker than that of the CD group. Vitamin A content in eggs of the ED group was significantly higher than that of the CD group. However, the difference in vitamin A content in eggs between the ED and CD groups was much smaller than that in the liver of the females between the two groups. These results indicate that feeding broodstock a higher level of vitamin A increases the vitamin A content in eggs but does not affect egg quality in Japanese flounder because excess dietary vitamin A was stored mainly in the broodstocks' liver. [ABSTRACT FROM AUTHOR]

SUMMARY: Lipid classes and fatty acid compositions of the muscles and eggs of wild and cultured sweet smelt in Korea from different habitats and fish culture farms were compared. Non-polar lipid (NL) content was in proportion to total lipid (TL) content and higher in the cultured fish muscles and eggs than in the wild fish. Phospholipid (PL) content showed almost no difference between the wild and cultured fish muscles. The fish eggs contained approximately three times as much PL as the fish muscles. The prominent NL classes of the fish muscles were triglyceride (TG) and free sterol (ST), and additionally, sterol ester (SE) was one of the prominent NL classes in the fish eggs. Each of the cultured fish muscles or eggs had proportions higher in TG and lower in ST compared with those of wild fish, respectively. These NL class proportions in fish muscles showed almost no difference in association with their wild habitats, fish culture farms as well as sex, while those in the fish eggs differed significantly. The PL class proportions of the fish muscles were similar in all samples, except those of the fish cultured in Miryang City. The wild fish muscles were rich in 16:1n-7, 18:3n-3 and 20:5n-3, whereas the fatty acid proportions showed almost no differences between fish habitats. The cultured fish muscles were rich in 18:1n-9, 18:2n-6, and 22:6n-3, in which the fatty acid proportions showed significant difference between fish farms due to different diets. [ABSTRACT FROM AUTHOR]

SUMMARY: Lipid classes and fatty acid compositions of the muscles and eggs of wild and cultured sweet smelt in Korea from different habitats and fish culture farms were compared. Non-polar lipid (NL) content was in proportion to total lipid (TL) content and higher in the cultured fish muscles and eggs than in the wild fish. Phospholipid (PL) content showed almost no difference between the wild and cultured fish muscles. The fish eggs contained approximately three times as much PL as the fish muscles. The prominent NL classes of the fish muscles were triglyceride (TG) and free sterol (ST), and additionally, sterol ester (SE) was one of the prominent NL classes in the fish eggs. Each of the cultured fish muscles or eggs had proportions higher in TG and lower in ST compared with those of wild fish, respectively. These NL class proportions in fish muscles showed almost no difference in association with their wild habitats, fish culture farms as well as sex, while those in the fish eggs differed significantly. The PL class proportions of the fish muscles were similar in all samples, except those of the fish cultured in Miryang City. The wild fish muscles were rich in 16:1n-7, 18:3n-3 and 20:5n-3, whereas the fatty acid proportions showed almost no differences between fish habitats. The cultured fish muscles were rich in 18:1n-9, 18:2n-6, and 22:6n-3, in which the fatty acid proportions showed significant difference between fish farms due to different diets. [ABSTRACT FROM AUTHOR]

Attempts to genetically identify eel eggs and larvae of the Japanese eel, which were collected from the estimated spawning site by using molecular characteristics. Amplification of the mitochondrial 16S ribosomal RNA gene; Genetic uniformity among the eggs and leptocephali site differences; Characteristics of artificially induced spawning and closely related taxa.