Comparative study on the protease inhibitors from fish eggs

The protease inhibitor was purified from five different fish eggs. The molecular weights of Pacific herring, chum salmon, pond smelt, glassfish, and Alaska pollock egg protease inhibitors were 120, 89, 84.5, 17, and 16.8kDa, respectively. The specific inhibitory activity of glassfish egg protease inhibitor was the highest followed by those of Pacific herring and Alaska pollock in order. The specific inhibitory activity and purity of glassfish egg protease inhibitor were 19.70 U mg^- 1 protein and 164.70 folds of purification, respectively. Glassfish egg protease inhibitor was reasonably stable at 50 - 65℃ and pH 8, which was more stable at high temperature and pH than protease inhibitors from the other fish species. Glassfish egg protease inhibitor was noncompetitive with inhibitor constant （Ki） of 4.44 nmol L^-1     

Spatiotemporal distribution of fish eggs and larvae in the Huanghe(Yellow) River estuary,China in 2005–2016

Decreasing fish resources in estuaries is a subject of anthropogenic activities.Studies of the spatiotemporal distribution of fish eggs and larvae can help identify the status and processes underlying recruitment in a fishery.As the fifth largest river estuary in the world,the Huanghe(Yellow)River estuary(HRE)is a typical estuary that has been seriously affected by human activities.Annual surveys on ichthyoplankton and environmental factors were conducted in the months of May of 2005 and 2009-2016 in the HRE to investigate the spatiotemporal distribution of fish eggs and larvae and the associated influencing factors.A total of 23 and 20 species of eggs and larvae,respectively,were collected.The dominant orders were Perciformes(51.2%)and Clupeiformes(25.6%).The average number of fish species eggs and larvae were 6.0 and 4.1 in average abundance of 0.91 and 0.13 ind./m~3,respectively.The dominant species were mainly low-commercial-value small-sized fishes,such as Clupanodon punctatus,Hare,ngula zutnasi,and Acanthogobius,whereas certain traditional commercial fishes,such as Trichiurus lepturus,and Clupea pallasii,were not seen.Analysis of the fish egg and larval community revealed four temporal assemblages and two spatial assemblages.Salinity was the main factor on the spatial distribution of ichthyoplankton communities,the species number and Shannon-Weiner diversity index(H')of the fish egg and larval community near the river mouth with lower salinity were significantly lower than the community far away from the river mouth with higher salinity.In addition,increases of water temperature promoted the number and abundance of fish species eggs,and the areas of abundant prey tended to have a more diversified and abundant of ichthyoplankton species.In overall,overfishing,dam construction,and other human activities were the main drivers that led to the substantial decline in fishery resources in the HRE.     

Embryonic and larval development in barfin flounder Verasper moseri (Jordan and Gilbert)

Broodstock of Verasper moseri (Jordan and Gilbert) aged 3–4 years old were selected, and reinforced cultivation was conducted to promote maturation under controlled water temperature and photoperiod conditions. Fertilized eggs were obtained by artificial fertilization, and the development of embryos, larvae and juveniles was observed continuously. The results showed that the fertilized eggs of V. moseri were spherical, with transparent yolk and homogeneous bioplasm, and had no oil globule inside. The average diameter of the eggs was 1.77±0.02 mm. The eggs of V. moseri were buoyant in water with salinity above 35. The cleavage type was typical discoidal. Young pigment cells appeared when olfactory plates began to form. Hatching occurred at 187 h after fertilization at a water temperature of 8.5°C. The newly hatched larvae, floating on the water surface, were transparent with an average total length of 4.69±0.15 mm. During the cultivation period, when the water temperature was raised from 9 to 14.5°C, 4-day old larvae showed more melanophores on the body surface, making the larvae gray in color. The pectoral fins began to develop, which enabled the larvae to swim horizontally and in a lively manner. On days 7–8, the digestive duct formed. The yolk sac was small and black. The yolk sac was absorbed on day 11. Larvae took food actively, and body length and body height clearly increased. The rudiments of dorsal and anal fin pterygiophores were discernible and caudal fin ray elements formed on day 19. On day 24, the larval notochord flexed upwards, and the rays of unpaired fins began to differentiate. Pigment cells converged on the dorsal and anal fin rays, and the mastoid teeth on the mandible appeared. On day 29, the left eyes of juveniles began to move upwards. Depigmentation began in some juveniles and they became sandy brown in color on day 37. Most juveniles began to settle on the bottom of the tank. The left eyes of juveniles migrated completely to the right side on day 50, when the average body length attained 2.5±0.18 cm, and juveniles accomplished metamorphosis to young. The embryonic and larval characters of several flounder species are compared.     

方斑东风螺不同批次卵质量的比较

2005年5月~8月在雷州市覃斗镇海威水产种苗基地的室内水池进行方斑东风螺亲螺培育,对亲螺不同批次产出的卵囊、卵、及其幼虫进行比较。结果表明:随着亲螺产卵批次的增加,亲螺产卵囊数、卵囊含卵数、产卵量逐次减少;卵囊长、宽逐次变小,厚逐次增加,形状由葵花子片状的比例大变为棒状的比例大;幼虫浮游期逐次延长;变态期幼虫壳长逐次变小;各批次之间的变态率逐次降低;卵径、孵化率、出囊幼虫大小差异不显著。     

Embryonic and larval development in barfin flounder Verasper moseri (Jordan and Gilbert)

Broodstock of Verasper moseri (Jordan and Gilbert) aged 3-4 years old were selected,and reinforced cultivation was conducted to promote maturation under controlled water temperature and photoperiod conditions.Fertilized eggs were obtained by artificial fertilization,and the development of embryos,larvae and juveniles was observed continuously.The results showed that the fertilized eggs of V.moseri were spherical,with transparent yolk and homogeneous bioplasm,and had no oil globule inside.The average diamete...     

Ontogenetic changes in digestive enzyme activities and the amino acid profile of starry flounder Platichthys stellatus

Ontogenetic changes in digestive enzyme activities and the amino acid(AA) profile of starry flounder,Platichthys stellatus,were investigated and limiting amino acids were estimated compared with the essential AA profile between larvae and live food to clarify starry flounder larval nutritional requirements.Larvae were collected at the egg stage and 0,2,4,7,12,17,24 days after hatching(DAH)for analysis.Larvae grew from 1.91 mm at hatching to 12.13 mm at 24 DAH.Trypsin and chymotrypsin activities changed slightly by 4 DAH and then increased significantly 4 DAH.Pepsin activity increased sharply beginning 17 DAH.Lipase activity increased significantly 4 DAH and increased progressively with larval growth.Amylase activity was also detected in newly hatched larvae and increased 7 DAH followed by a gradual decrease.High free amino acid(FAA) content was detected in starry flounder eggs(110.72mg/g dry weight).Total FAA content dropped to 43.29 mg/g in 4-DAH larvae and then decreased gradually to 13.74 mg/g in 24-DAH larvae.Most FAAs(except lysine and methionine) decreased 50%in 4-DAH larvae compared with those in eggs and then decreased to the lowest values in 24-DAH larvae.Changes in the protein amino acid(PAA) profile were much milder than those observed for FAAs.Most PAAs increased gradually during larval development,except lysine and phenylalanine.The percentages of free threonine,valine,isoleucine,and leucine decreased until the end of the trial,whereas the protein forms of these four AAs followed the opposite trend.A comparison of the essential AA composition of live food(rotifers,Artemia nauplii,and Artemia metanauplii) and larvae suggested that methionine was potentially the first limiting AA.These results may help develop starry flounder larviculture methods by solving the AA imbalance in live food.Moreover,the increased digestive enzyme activities indicate the possibility of introducing artificial compound feed.     

Changes of Protein and Lipid Contents,Amino Acid and Fatty Acid Compositions in Eggs and Yolk-Sac Larvae of American Shad(Alosa sapidissima)

To investigate the changes of the biochemical composition of American shad(Alosa sapidissima) eggs and larvae at embryonic and early larval stages, samples were collected at different development stages from artificial fertilization to the end of yolk absorption including 2 h, 12 h and 30 h after fertilization and newly hatched larvae including 1 and 3 days after hatching. The composition of lipid, fatty acids, protein and amino acids were analyzed. The content of total protein exhibited a decreasing trend during embryogenesis and larval development, and a significant reduction was detected after hatching(P 0.05). The total lipid content remained relative stable. A significant reduction was detected in almost all amino acids after hatching except for glycine(P 0.05), while a significant decrease was found in the content of cysteine, proline, tyrosine, valine, isoleucine, leucine and phenylalanine during the yolk-sac phase(P 0.05). On the other hand, all the groups of fatty acids remained stable during the period of embryogenesis. But after hatching, a significant decrease was found in the content of C18:2n-6, C18:3n-6, SFA and ratio of EPA/ARA(P 0.05), while a significant increase was found in the content of C18:3n-3, C20:4n-6, C22:6n-3 and ratio of n-3/n-6(P 0.05). In conclusion, the combined data suggested that American shad utilizes the protein content as preferential energy substrates during embryonic and early larval developments with some specificity in the consumption of different amino acids.     

Ontogenetic changes in digestive enzyme activities and the amino acid profile of starry flounder <Emphasis Type="Italic">Platichthys stellatus</Emphasis>

Ontogenetic changes in digestive enzyme activities and the amino acid (AA) profile of starry flounder, Platichthys stellatus, were investigated and limiting amino acids were estimated compared with the essential AA profile between larvae and live food to clarify starry flounder larval nutritional requirements. Larvae were collected at the egg stage and 0, 2, 4, 7, 12, 17, 24 days after hatching (DAH) for analysis. Larvae grew from 1.91 mm at hatching to 12.13 mm at 24 DAH. Trypsin and chymotrypsin activities changed slightly by 4 DAH and then increased significantly 4 DAH. Pepsin activity increased sharply beginning 17 DAH. Lipase activity increased significantly 4 DAH and increased progressively with larval growth. Amylase activity was also detected in newly hatched larvae and increased 7 DAH followed by a gradual decrease. High free amino acid (FAA) content was detected in starry flounder eggs (110.72 mg/g dry weight). Total FAA content dropped to 43.29 mg/g in 4-DAH larvae and then decreased gradually to 13.74 mg/g in 24-DAH larvae. Most FAAs (except lysine and methionine) decreased >50% in 4-DAH larvae compared with those in eggs and then decreased to the lowest values in 24-DAH larvae. Changes in the protein amino acid (PAA) profile were much milder than those observed for FAAs. Most PAAs increased gradually during larval development, except lysine and phenylalanine. The percentages of free threonine, valine, isoleucine, and leucine decreased until the end of the trial, whereas the protein forms of these four AAs followed the opposite trend. A comparison of the essential AA composition of live food (rotifers, Artemia nauplii, and Artemia metanauplii) and larvae suggested that methionine was potentially the first limiting AA. These results may help develop starry flounder larviculture methods by solving the AA imbalance in live food. Moreover, the increased digestive enzyme activities indicate the possibility of introducing artificial compound feed.     

苏氏圆腹胚胎发育的初步观察

观察两批苏氏圆腹受精卵的胚胎发育,描述并记录胚胎发育各期的形态特征及发育时间。结果表明:苏氏圆腹成熟卵呈圆球形,淡黄色,富有光泽,卵黄分布均匀,相对密度略大于水,卵径0.93～1.11 mm,平均0.98±0.19 mm。受精卵吸水后呈微黏性,属黏性卵,卵膜略膨胀,卵径0.99～1.15 mm,平均1.08±0.27 mm。苏氏圆腹胚胎发育属于盘状卵裂,与其他淡水硬骨鱼类基本相似。其发育过程可分为:受精卵、卵裂期、囊胚期、原肠期、神经胚期、器官分化期、出膜期和初孵仔鱼。在水温26±1℃的条件下,苏氏圆腹胚胎孵化历时24 h 45 min,总积温640.90 h.℃。初孵仔鱼体全长3.20～3.60 mm。     

军曹鱼仔鱼期的摄食与生长

以人工孵化的军曹鱼(Rachycentron canadum)卵黄囊期仔鱼为材料,对仔鱼早期阶段的摄食及生长情况进行研究。结果表明:在水温28~32℃条件下,军曹鱼仔鱼3日龄开始摄食,6日龄时卵黄完全耗尽,6~7日龄饥饿仔鱼进入不可逆点(PNR)期;混合营养期3~4 d。饥饿仔鱼的初次摄食率开始较低,此后上升,到卵黄囊快要耗尽时达高峰(50%),以后又下降。内营养期,仔鱼日平均生长率为0.86 mm/d;PNR前的摄食期,饥饿仔鱼的日平均增长率为0.068 mm/d,而摄食仔鱼的日平均生长率为0.64 mm/d;PNR后至死亡前,饥饿仔鱼体长呈负增长,而摄食仔鱼的日平均生长率达1.04 mm/d。摄食仔鱼在孵化后8 d内的全长和日龄呈指数关系;前10 d的口径与全长呈正比关系。     

Ichthyoplankton recruitment from mainstream of the Changjiang River into the Dongting Lake,the second largest freshwater lake in China

Floodplains are important and distinctive ecosystems around the world, and the recruitment of ichthyoplankton from river to floodplain lakes is crucial to maintain this unique ecosystem. However,this process has not been well documented. In this study, ichthyoplankton were sampled to investigate the details of ichthyoplankton recruitment from the Changjiang(Yangtze) River to the Dongting Lake via a floodway channel, the Songzi River, from May to July in 2013 and 2014. During the study period, 41 species of eggs and larvae were sampled. Among the samples, 16 were river-lake migratory species(RL), representing23.5% of the species in the Dongting Lake. In 2013, an estimated 130 million eggs and 3 180 million larvae drifted through the sampling section, and in 2014, an estimated 1 060 million eggs and 1 040 million larvae drifted through the sampling section. The amount of eggs and larvae of RL reached 3 210 million in 2013 and 1 850 million in 2014, respectively. These results demonstrated the importance of ichthyoplankton recruitment from the river to the lake, as species diversity will decrease sharply without this recruitment.Canonical correspondence analysis(CCA) showed that water temperature and water flow are the two most important factors influencing the spawning activities of fish. To maintain the high fish diversity in the Changjiang floodplain, we suggest to irrigate the channel to increase water discharge and increase the transport of ichthyoplankton from the Changjiang mainstream into the Dongting Lake.     

Distribution and elimination of Norfloxacin in Fenneropenaeus chinensis larvae

This study examined the distribution and elimination of Norfloxacin(NFLX) in Fenneropenaeus chinensis ovary and egg and newly hatched larvae.Mature parental shrimp were exposed to 4 or 10 mg L 1NFLX for 2 or 5 d.Ovary and eggs of the shrimp were sampled after spawning in order to detect NFLX residue using high-performance liquid chromatography(HPLC).Results showed that NFLX residue accumulated in F.chinensis eggs after the parental exposure,with the highest residue detected in ovary.To examine the fate of NFLX residue in larvae,we further determined the concentration of NFLX residue in F.chinensis eggs and larvae at 4 different developmental stages after 24-h exposure.From the newly metamorphosed larvae(0 h post-metamorphosis,h.p.m),samples were taken at different time intervals to 72 h.p.m.HPLC assay showed that the concentrations of NFLX residue in zoea exposed to 4 and 10 mg L 1NFLX were the highest at 1.5 h,i.e.,0.332 and 0.454 μg g 1,respectively.At the two NFLX exposure levels,the elimination time of half NFLX(half life) in nauplius was 45.36 and 49.85 h,respectively,followed by that in zoea(31.68 and 33.13 h),mysis larvae(42.24 and 47.28 h) and postlarvae(24.48 and 30.96 h).Both NFLX exposure levels had a germicidal effect.The distribution and elimination of NFLX residue in F.chinensis tissue,eggs and larvae correlated well with the drug exposure level.The disappearance of NFLX residue coincided with the larval growth,and the half-life of NFLX decreased with the larval development.     

Embryonic development of Pelteobagrus fulvidraco （Richardson, 1846）

1 INTRODUCTION Pelteobagrus fulvidraco (Richardson, 1846) or yellow catfish is slender and scaleless with a gently sloping dorsal profile from anterior to posterior. It is generally black-brown to black-yellow on the back, light yellow on the belly, with …     

Analysis of Buoyancy Module Auxiliary Installation Technology Based on Numerical Simulation

To reduce the requirement for lifting capacity and decrease the hoist cable force during the descending and laying process of a subsea production system (SPS), a buoyancy module auxiliary installation technology was proposed by loading buoyancy modules on the SPS to reduce the lifting weight. Two models are established, namely, the SPS lowering-down model and the buoyancy module floating-up model. The main study results are the following: 1) When the buoyancy module enters the water under wave condition, the amplitude of tension fluctuation is twice that when SPS enters water; 2) Under current condition, the displacement of SPS becomes three times larger because of the existence of the buoyancy module; 3) After being released, the velocity of the buoyancy module increases to a large speed rapidly and then reaches a balancing speed gradually. The buoyancy module floats up at a balancing speed and rushes out from the water at a pop-up distance; 4) In deep water, the floating-up velocity of the buoyancy module is related to its mass density and shape, and it is not related to water depth; 5) A drag parachute can reduce floating-up velocity and pop-up distance effectively. Good agreement was found between the simulation and experiment results.     

中华乌塘鳢个体生殖力的研究

研究了湛江沿海中华乌塘鳢个体生殖力及其与生物学指标的关系。结果表明 :个体绝对生殖力为 840 0～ 3 3 2 70粒 ,个体相对生殖力FL 为 5 67 6～ 1 83 3 2粒 /cm ,Fw为 1 5 5 6～ 482 7粒 /g ;个体绝对生殖力与体长、体重、空壳重、卵巢重呈直线相关 ,与年龄呈二次函数相关 ,与成熟系数和肥满度相关关系不显著 ;个体相对生殖力FL 与各生物学指标正相关 ,Fw除了与卵巢重、肥满度和年龄相关关系不显著外 ,其余均显著相关     

Sodium and potassium in the bones of penguin and skua revealed by EPR and SR-XRF technique

Penguin and skua in the maritime Antarctic have high salt loadings in the body due to almost exclusive diet consumption of marine invertebrates. However, the storage and turnover of sodium and potassium in these animals are poorly investigated. Here we determined the concentration and microscopic distribution of the two elements in the bones of penguin and skua. The average concentrations of sodium and potassium in penguin bone were comparable with that in skua bone (0.18% and 0.82% for penguin bone; 0.19% and 0.76% for skua bone in dry weight). The ratios of sodium to calcium and potassium to calcium (0.0330 and 0.0075 for penguin, 0.0335 and 0.0082 for skua in average by weight) were somewhat higher than the reported ratios for terrestrial animals, indicating these marine animals' bone enrichment of salt. The ratios of sodium to potassium in average by weight were 6.75 and 4.65 for penguin and skua, respectively. This value is much lower compared with the bulk sea water ratio of about 27.0, implying that potassium is favorable to reside in the bone rather than sodium. Both sodium and potassium were found to significant correlation with the content of organic materials in bone based upon the intensity of native signal determined by electron paramagnetic resonance (EPR). It was estimated that almost all of potassium is kept within the organic phases, while about 30% of sodium is stored in organic phases and the other 70% within mineral phase. The microscopic distributions of potassium in the cross-section and/or surface were revealed by synchrotron radiation X-ray fluorescence (SR-XRF) technique. The ratio of potassium to calcium based upon the SR-XRF intensity counter varied considerably from the surface to the interior, and on the surface the highest concentration of potassium was observed in the middle section with decreasing amounts toward the edge. This indirectly documented that exchange of potassium between fluid and bone organic phase maybe occur.     

Reproduction ecology of fishes in Jiaozhou Bay waters

Observations on gonad development of 84 species of marine fishes in Jiaozhou Bay waters showed the breeding periods of more than 50 of these species are mostly from April to August, with peaks between May to June. A great many of the species spawn in the warm season, only a few species in the cold season. The number of spawning species increases with the rise and decreases with the fall in water temperature. The absolute fecundity of 50 teleost species, which usually increases with body length and weight, was estimated to range from about 300 to 9,000,000 eggs. The reproductive patterns of fishes in Jiaozhou Bay waters are discussed. This paper was presented at the IV International Congress of Ecology, held at Syracuse, USA in August, 1986. Contribution No. 1553 from the Institute of Oceanology, Academia Sinica.     

温度对匙吻鲟胚胎与仔鱼发育的影响

研究不同温度下匙吻鲟(Polyodon spathula)的胚胎与仔鱼发育。结果表明,26℃时,匙吻鲟胚胎发育到大卵黄栓期全部死亡;在15～24℃范围内,胚胎均可孵化出膜,孵化时间与温度呈极显著的负相关关系(P<0.01)。胚胎发育的最适温度范围为18～22℃,最佳温度为20℃,生物学零度为12.30℃。卵黄囊期仔鱼历时随温度的升高而缩短。在16～22℃范围内,温度对卵黄囊期仔鱼生长的影响极显著(P<0.01),22～24℃影响不显著(P<0.05)。在22～26℃范围内,仔鱼生长的差异不显著(P<0.05),成活率低,且畸形率极显著地高于16～20℃(P<0.01)。匙吻鲟仔鱼早期发育的最适温度范围为18～20℃,温度过高是造成仔鱼畸形率增加的主要原因之一。     

Characteristics of the tertiary egg membrane of cuttlefish Sepiella maindroni de Rochebrune

We separated tertiary egg membrane (TGM) from 2- and 25-day-old eggs of cuttlefish Sepiella maindroni de Rochebrune, and revealed its ultrastructure, physical (solubility, barrier property) and biochemical (histology, histochemistry, nutritional components, bacteriostasis) characteristics. The results show that TGM could not be dissolved with natural seawater, alcohol, ether or hydrochloric acid (HCl), but it could be dissolved with 2-chloroethanol, diethylamine, and sodium hydroxide (NaOH). The black TGM was more effective in blocking off mud particulates, microorganisms (Chlorella vulgaris, Vibrio alginolyticus) and lighter than the white TGM. The elasticity of black and white TGMs was 1.8 N and 1.5 N, respectively. There were some ink particulates and rod-shaped bacteria in the black TGM. The nutritional components were different between black and white TGMs: Lipid content was lower and protein content was higher in the black TGM. TGM could also inhibit the growth of Vibrio alginolyticus.     

Zooplankton Distribution in Coastal Water off Gopalpur,North-Western Bay of Bengal

An interannual study on zooplankton abundance, biomass, and species composition was carried out during different seasons in two local coastal water types off Gopalpur, north-western Bay of Bengal. Although, Type-1 was observed with higher zooplankton abundance in comparison to Type-2, pattern of variation followed similar seasonal trends in both water types during individual years. Well pronounced seasonality was observed in zooplankton distribution. Zooplankton community was composed of 217 holoplankton and 22 meroplankton. The holoplankton community was predominated by copepod in terms of species diversity and abundance followed by hydrozoa, tintinnida, malacostraca, gastropoda, chaetognatha and chordata. The meroplankton were represented by larval forms viz. bivalve veliger, brachyuran zoea larvae, caridean larvae, copepod nauplii, fish egg and gastropod veliger. Dominance of copepod species viz. Acrocalanus longicornis, Paracalanus aculeatus and Paracalanus parvus were observed frequently in both water types. The species richness was higher in Type-1 in comparison to Type-2 during both the years. Salinity regimes and availability of phytoplankton prey influenced the distribution and species composition of zooplankton assemblage.