虾夷扇贝横纹肌和平滑肌的蛋白分布及理化性质

为探讨虾夷扇贝闭壳肌中横纹肌(ST)和平滑肌(SM)蛋白分布特征及理化性质差异。对肌肉组织进行切片、苏木精—伊红染色后,在光学显微镜下观察肌肉组织形态,SDS-PAGE分析蛋白组成,通过盐溶性和Ca~(2+)-ATPase对理化性质进行了比较研究。研究表明,横纹闭壳肌的肌纤维更粗,肌细胞间更致密;Myorod蛋白仅存在于平滑闭壳肌中,在横纹闭壳肌中不存在;副肌球蛋白在平滑闭壳肌中含量为31%,横纹肌中仅为11%。2种肌肉盐溶曲线也完全不同,在0.05~1.0 mol/L盐浓度范围内平滑肌的溶解性呈S型曲线上升,而横纹肌呈直线型上升,这种差异可能与副肌球蛋白含量有关。此外,平滑肌和横纹肌肌原纤维蛋白Ca~(2+)-ATPase最适温度分别为35和30°C,活化能分别为23.4和11.3 k J/mo L。     

Feeding habits of albacore Thunnus alalunga in the transition region of the central North Pacific

ABSTRACT:   The feeding habits of albacore Thunnus alalunga (fork length: 48.9–76.2 cm, n  = 132) were examined from late spring to early autumn in relation to its northward migration in the transition region between the subtropical and subarctic fronts in the central North Pacific. Samples were collected at night using surface gill nets or during daytime pole-and-line surveys in 2001 and 2002. During May and June, albacore fed mainly on Japanese anchovy Engraulis japonicus , which accounted for 27.2%, 67.0%, and 45.5% of the total stomach contents by number ( Cn ), wet weight ( WW ), and frequency of occurrence ( F ), respectively, and secondarily on the subarctic gonatid squid Gonatopsis borealis ( Cn , 15.8%; WW , 10.8%; F , 28.8%). From July to September, albacore continued to depend on Japanese anchovy ( Cn , 48.2–52.8%; WW , 79.9–95.2%; F , 27.8–85.4%). These results corresponded well with the remarkable rebound of the Japanese anchovy stock since the 1990s. Gonatopsis borealis , the main squid prey from May to June, almost disappeared from the stomachs of albacore from July to September, probably due to the northward migration of this squid to subarctic waters in summer. The feeding impact of albacore on the Japanese anchovy stock in the transition region was conservatively estimated to be from 1400 to 2100 tons per day from late spring to early autumn.     

Prey selection of common minke (Balaenoptera acutorostrata) and Bryde's (Balaenoptera edeni) whales in the western North Pacific in 2000 and 2001

A study of common minke and Bryde's whales was conducted in the western North Pacific in the 2000 and 2001 summer seasons to estimate prey selection of cetaceans as this is an important parameter in ecosystem models. Whale sighting and sampling surveys and prey surveys using quantitative echosounder and mid‐water trawl were carried out concurrently in the study. Biomasses of Japanese anchovy, walleye pollock and krill, which were major prey species of common minke and Bryde's whales, were estimated using an echosounder. The results suggested that common minke whale showed prey selection for Japanese anchovy while they seemed to avoid krill in both the offshore and coastal regions and walleye pollock in the continental shelf region. Selection for shoaling pelagic fish was similar to that in the eastern North Atlantic. Bryde's whale showed selection for Japanese anchovy in August 2000 and July 2001, while it showed prey selection for krill in May and June in 2001.     

牙鲆血清免疫球蛋白的分离纯化及部分特性分析

运用Sephacryl S-200凝胶层析和HiTrap rProtein ASepharose亲和层析2种方法对牙鲆(Paralichthys olivaceus)血清免疫球蛋白进行分离纯化,结果表明,牙鲆免疫球蛋白分布于33%~50%的硫酸铵饱和溶液中,其中45%的分离效果最好。凝胶层析和亲和层析样品均出现2个蛋白峰,用还原SDS-PAGE检测确定牙鲆免疫球蛋白存在于第2个蛋白峰中。牙鲆免疫球蛋白重链分子量约为75.4 kD,轻链分子量约为29.9 kD和28.2 kD,推测牙鲆血清免疫球蛋白的分子量为836 kD。制备了兔抗牙鲆免疫球蛋白多克隆抗体,免疫双扩散法检测多克隆抗体效价为1∶32,免疫斑点法检测多克隆抗体效价至少为1∶1 600。运用免疫印迹法(Western-bloting)检测了兔抗牙鲆免疫球蛋白多克隆抗体的特异性,实验证明该抗体与牙鲆全血清中免疫球蛋白重链、轻链反应均成阳性。     

Effects of glutathione treatments during sperm washing and in vitro fertilization on the in vitro early development of embryos of Japanese Black cattle

This study was conducted to examine the effects of adding glutathione (1 mM) to media used for sperm washing and in vitro fertilization (IVF) on the improvement of early development of embryos produced using cryopreserved spermatozoa of the less IVF-competent bull (the one considered unqualified as spermatozoa supplier for the production of bovine blastocysts using IVF). The cryopreserved spermatozoa of this bull were characterized by normal motility and lower ATP content and blastocyst productivity than those of IVF-competent bulls. The addition of glutathione to the sperm washing medium was more effective in improving the productivity of blastocysts and ATP content than the addition of glutathione to the IVF medium or no glutathione addition at all (control). These results suggest that this simple method may be used to improve the potential of cryopreserved spermatozoa of less IVF-competent bulls to fertilize oocytes in vitro and to induce normal embryonic development after fertilization.     

扇贝壳抛光设备的改进设计

针对原抛光设备作业中存在的问题,对抛光设备的传动系统、抛光系统等关键部分进行了改进设计。改进后的设备总体布局合理,结构简单,操作安全可靠,易损件拆卸简便,能够较好地满足实际生产的要求。经生产运行的实践证明:抛光后的贝壳表面光滑,生产效率提高了2.5倍。     

Efficacy of Netminder® silicone release coating for biofouling reduction in bay scallop grow‐out and comparative effects on scallop survival,growth and reproduction

Netminder^®, a water‐based silicone barrier release coating, was highly effective in reducing biofouling of lantern nets during grow‐out/overwintering of bay scallops, Argopecten irradians irradians, in a large‐scale restoration programme in New York, USA. Compared with untreated nets, scallops held in Netminder^®‐coated nets experienced reduced survival after 8 months, probably due to higher loads of epibionts on their shells. However, this was countered by higher reproductive and overall condition of scallops in treated vs. untreated nets; there were no consistent differences in shell growth in different net treatments. Although further testing is recommended under a wider range of conditions, we conclude that for the purposes of our scallop restoration work, coating nets with Netminder^® would eliminate the need for a gear change in spring, thus reducing labour costs; the coating process should be refined so that Velcro closures of nets do not become sealed shut.     

Comparison of early life history stages of the bay scallop, Argopecten irradians: Effects of microalgal diets on growth and biochemical composition

The culture of bay scallops, Argopecten irradians, is limited by a reliable and affordable supply of spat and the ability to ensure that animals attain market size within a single growing season. The main goals of our study were thus: (1) to develop growth-optimizing algal diets for implementation in hatcheries, and (2) to identify and compare bay scallop postlarval and juvenile dietary requirements, especially of lipids and fatty acids, which if met may enhance production. Nutritional needs of postlarval bay scallops (present study) are compared with those of sea scallops, Placopecten magellanicus, offered the same diets in a previous companion study. To this end, postlarval (initial shell height, SH = 240 μm) and juvenile (initial SH = 10 mm) bay scallops were offered 6–7 microalgal diet combinations at 20 °C, for 3 weeks. A similar growth ranking among diets was observed between the two developmental stages. A combination diet of Pavlova sp. (CCMP 459) and Chaetoceros muelleri was far superior to any other diet tested, yielding growth rates of 58 and 357 μm day^− 1 which were 65% and 25% higher than the next highest performing diet of Tetraselmis striata/C. muelleri in postlarvae and juveniles, respectively. The T. striata/C. muelleri diet, which is limited in the n-3 fatty acid docosahexaenoic acid (DHA), yielded very poor growth of sea scallop postlarvae in a prior study, indicating that bay scallops may have less stringent requirements for DHA than sea scallops. The Pav 459/C. muelleri diet, which also supported the highest growth of sea scallop postlarvae, is characterized by elevated levels of the n-6 fatty acids, arachidonic (AA) in C. muelleri and 4,7,10,13,16-docosapentaenoic (DPA) in Pav 459. The two diets deficient in AA and n-6 DPA, Pavlova lutheri/Thalassiosira weissflogii and P. lutheri/Fragilaria familica, yielded the lowest growth rates in both bay scallop postlarvae and juveniles. Tissue enrichment of these two fatty acids relative to the diet, as well as overall enrichment in ∑n-6 fatty acids was observed across developmental stages and dietary treatments. A similar pattern has previously been observed in sea scallop postlarvae, suggesting a dietary requirement for n-6 fatty acids in pectinids that has often been overlooked in the past.     

Seasonal Changes in Rigor Development and Flesh Texture of Wild Japanese Sea Bass (Lateolabrax japonicus)

The season for finding the firmest sashimi made from wild Japanese sea bass was investigated. Flesh rigor tension and contraction were measured by a “new” device with isometric (muscle length kept constant) and isotonic (balance beam moves freely) transducers. Both flesh rigor tension and contraction peaks appeared at the same postmortem times, with attainment of ultimate pH and adenosine triphosphate/inosine monophosphate ratio in four seasons. Seasonal seawater temperature correlated negatively to seasonal maximum rigor contraction and positively to seasonal flesh breaking strength at 72 h postmortem. After rigor peak tension attainment, the tension relaxation was much lower than that of other wild fish species, especially in summer. The sea bass muscle resisted structure disruption in rigor isometric tension generation. Wild sea bass sashimi was firmest in breaking strength in summer.     

Effects of high dose of vitamin A on reproduction and egg quality of Japanese flounder Paralichthys olivaceus

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.