Growth and ontogenetic development of digestive functionality in black Amur bream (Megalobrama terminalis)

The function of digestive physiology during ontogenetic development is essential to ensure high survival and growth rates. In order to evaluate the digestive physiological capacity of the black Amur bream (Megalobrama terminalis), changes of morphology and digestive enzyme activity (trypsin, lipase, amylase, pepsin, leucine aminopeptidase and alkaline phosphatase) in larvae were examined from hatching to 40 days after hatching (DAH). Results indicated that fluctuation patterns differed between the total and specific activities of the digestive enzymes. The total activities of these six enzymes gradually increased throughout the fish growth. The specific activity of trypsin peaked at 5 DAH and then decreased dramatically, while it increased remarkably again from 8 to 10 DAH and remained stable level after 20 DAH. Pepsin activity was first examined in M. terminalis at 15 DAH and gradually elevated towards the end of the experiment. The specific activity of lipase displayed obvious peaks at 5 and 20 DAH. For the amylase, its specific activity reached plateau at 4 DAH, underwent sharp decrease, and remained stable after 20 DAH. In addition, we found that the specific activity of alkaline phosphatase raised significantly from hatching to 5 DAH, and tended to keep slight fluctuation after 15 DAH. From the above, we concluded that the specific activities of digestive enzymes in the larvae varied constantly from 3 to 20 DAH and turned relatively stable after 20 DAH. The present study provides effective information that is useful to improve the seedling cultivation and the technology for healthy breeding.     

鞍带石斑鱼仔稚（幼）鱼的发育和生长研究

对鞍带石斑鱼的仔稚幼鱼形态发育的各个阶段进行了观察与研究,详细描述从初孵仔鱼到幼鱼各个发育时期的形态特征和发育时间。根据卵黄囊的变化,长鳍棘的长出与收缩,鳞片和体色斑纹的出现,鞍带石斑鱼胚后发育可以划分为仔鱼期、稚鱼期、幼鱼期。仔鱼期又可分为卵黄囊期仔鱼和后期仔鱼。水温27～30℃,盐度27～31,pH值8.0～8.4的海水中培育,初孵仔鱼至孵化后2日龄为卵黄囊期仔鱼。2日龄仔鱼开口,3日龄至20日龄为后期仔鱼,22日龄至30日龄为稚鱼期,31日龄进入幼鱼期。鞍带石斑鱼胚后发育过程中最明显的变化是背鳍棘和腹鳍棘的生长和收缩,也是生产育苗当中比较关键的仔稚幼鱼变态过程。     

Dietary n‐3 highly unsaturated fatty acids affect the biological and serum biochemical parameters,tissue fatty acid profile,antioxidation status and expression of lipid‐metabolism‐related genes in grass carp,Ctenopharyngodon idellus

A 95‐day feeding trial was conducted to determine the effects of n‐3 highly unsaturated fatty acids (n‐3 HUFA) on the growth, antioxidation and lipid metabolism in grass carp (Ctenopharyngodon idellus). Two isonitrogenous and isolipidic diets were formulated with either lard oil (LO) or fish oil (FO) as the main lipid source. The results showed that the intraperitoneal fat (IPF) ratio was significantly lower (P < 0.05) in FO group. The concentration of n‐3 HUFA in muscle, hepatopancreas and IPF was significantly higher in FO group (P < 0.05). The serum low‐density lipoprotein (LDL) content was significantly lower (P < 0.05), and glucose (GLU) content was significantly higher (P < 0.05) in FO group. The serum total superoxide dismutase (T‐SOD) activity was significantly higher (P < 0.05) in FO group, consistent with the serum malondialdehyde (MDA) content. The gene expression of IPF fatty acid synthase (FAS), acetyl‐CoA carboxylase (ACC), sterol regulatory element‐binding protein (SREBP‐1) and peroxisome proliferator‐activated receptor γ (PPARγ) was significantly lower (P < 0.05) and that of peroxisome proliferator‐activated receptor α (PPARα) was significantly higher (P < 0.05) in FO group compared with LO group. Similar trends were found in the hepatopancreas, except for PPARγ. It is suggested that n‐3 HUFA could inhibit lipid accumulation in grass carp by affecting the expression of lipid‐metabolism‐related genes.     

Characterization of Collagen Enzymatic Hydrolysates Derived from Lizardfish (Synodus fuscus) Scales

Acid soluble collagen was extracted from the scales of lizardfish and characterized with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and amino acid analysis. After 8 h of collagen hydrolysis, hydrolysates had an estimated degree of hydrolysis (DH) from 4 ± 0.05 to 25 ± 0.63% (p < 0.05). All hydrolysates had angiotensin converting enzyme inhibitory and antioxidant activity. These activity levels showed little change after treatment with gastrointestinal proteases. Results indicated that the lizardfish by-products may be improved by enzymatic treatment with acid-soluble collagen from lizardfish scales.     

Apparent digestibility coefficients of selected feed ingredients for juvenile snakehead,Ophiocephalus argus

Apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude lipid, gross energy, phosphorus and amino acids in Peruvian fish meal, poultry by‐product meal, meat and bone meal, spray‐dried blood meal, hydrolysed feather meal, corn gluten meal, soybean meal, peanut meal, cottonseed meal and rapeseed meal were determined for juvenile snakehead (Ophiocephalus argus) with initial mean body weight of 78.1 g. A reference diet and test diets that consisted of a 70 : 30 mixture of the reference diet to test ingredient were used with 5 g kg^?1 Cr₂O₃ as an external indicator. Fish meal, poultry by‐product meal and corn gluten meal had higher ADCs of dry matter, crude protein, and gross energy among ingredients tested. Dry matter ADCs ranged 61.9–81.5% for animal ingredients and corn gluten meal and ranged 52.2–68.0% for soybean meal, peanut meal, cottonseed meal and rapeseed meal. Energy ADCs of ingredients followed similar trends to differences in dry matter digestibility. Protein ADCs of animal and plant ingredients ranged 73.6–92.8% and 75.3–85.6%, respectively. Amino acid ADCs generally reflected protein digestibility. Lipid ADCs were relatively high for the ingredients tested. Phosphorus ADCs of animal and plant ingredients ranged 39.5–65.2% and 38.7–57.1%, respectively.     

贻贝采卵试验报告

为了探讨贻贝人工育苗的规模、数量、茬次等问题，本文对采卵的规律进行了研究。通过在不同季节和时期用变温刺激法来诱导排卵试验，认为在春季应用升温为主的常规综合刺激法，其排卵宁可达到60%以上；在秋季应以降温为主的变温刺激法，排卵率可达到40-60%。此外，文中对不同年龄的亲贝所排放生殖细胞的雌雄比例和采卵量等问题进行了讨论。     

Cryopreservation of strip spawned sperm using non‐programmable freezing technique in the blue mussel Mytilus galloprovincialis

In this study, a non‐programmable freezing technique has been developed with the strip spawned blue mussel (Mytilus galloprovincialis) sperm. The key parameters optimized including (1) cryoprotectant agents (CPAs); (2) cooling temperature; (3) thawing temperature; (4) sugar and amino acid supplementation and (5) sperm to egg ratio. The fertilization rate and/or integrity of plasma membrane and acrosome were used as sperm quality assessment indicators. The highest post‐thaw sperm fertilization rate of 95% was achieved, when sperm were cryopreservated in 8% dimethyl sulfoxide at 7.8 cm above the liquid nitrogen surface and thawed in a 60°C seawater bath. The addition of glucose, sucrose or trehalose in dimethyl sulfoxide did not, whereas 0.8% glycine did significantly improve the post‐thaw sperm fertilization rates. The fluorescent evaluation has demonstrated that the addition of glycine significantly improved the post‐thaw sperm acrosome integrity, revealing a positive role of glycine in the improvement of post‐thaw sperm quality in blue mussels.     

Surface-exposed expression of Edwardsiella tarda EseB in live attenuated Vibrio anguillarum based on novel surface display systems

Live, attenuated Vibrio anguillarum strains can serve as vectors for the delivery of heterologous antigens for development of multivalent recombinant vaccines. Based on the outer membrane anchoring elements of V. anguillarum , we have previously constructed several efficient surface display systems Lpp-Omporf1, Lpp-OmpU, Lpp-Omp26La, Wza-Omporf1, Wza-OmpU and Wza-Omp26La. In this study, with these constructed surface display systems, a putative antigen protein EseB from pathogenic Edwardsiella tarda was successfully expressed on the surface of an attenuated V. anguillarum strain to get multivalent vaccine candidates. Further immune protection evaluation in zebra fish ( Danio rerio ) demonstrated that the V. anguillarum EseB-display strain AV/pW-26La-B could trigger full protection against V. anguillarum infection and early protection against E. tarda infection in the immunized fish. These results suggest that surface display of heterologous protective antigens in attenuated V. anguillarum could be used as a tool to develop potential V. anguillarum vector vaccine.     

日本对虾越冬亲虾性腺促熟及工厂化育苗技术研究

1997、1998年利用越冬亲虾进行性腺促熟,用镊烫法切除眼柄,促进亲虾发育。结果:两年共培育亲虾雌虾8204尾。雄虾5683尾,获交尾虾5360尾。交尾率为71.81％。每年两批育苗,共利用水体1720m~3,育出0.7～1.1cm的虾苗12450万尾,平均单位水体出苗量为7.24万尾/m~3,效益显著。     

文蛤增养殖区主要环境因子变化规律研究

2004年和2005年分别对江苏省沿海滩涂4个具有代表性的文蛤重点增养殖区的环境因子进行了连续调查、监测和研究,主要分析测试了以下3个对文蛤生存影响较为重要的环境因子:底泥中的硫化物(S2-)、底泥渗水中的总氨氮(NH4-N)和底泥渗水中的化学需氧量(COD)。结果表明:S2-季节性变化明显,地点上随监测站位不同有显著差异;NH4-N夏季较高,其它时段基本无变化,均值远远高于上覆水体;COD含量除受气温影响外,还显著受到人类生产生活(如排污等)的影响。另外,2005年较2004年部分监测站位养殖环境有恶化趋势。