Isolation and characterization of 45 Polymorphie microsatellite loci of turbot (Scophthalmus maximus) and cross-species amplification

Turbot(Scophthalmus maximus) is a flatfish species commercially important for aquaculture.In this study,we generated a microsatellite-enriched genomic DNA library for Scophthalmus maximus,and then isolated and characterized 45 microsatellite loci by genotyping 30 individuals.The observed number of alleles ranged from 2 to 19 with an average of 6.24,while the effective number of alleles ranged from 1.30 to 11.11 with an average of 3.66.The expected heterozygosities varied from 0.235 to 0.925 4 and polymorphic information content ranged from 0.204 4 to 0.903 3,with an average of 0.622.Twelve loci deviated significantly from Hardy-Weinberg equilibrium,and no significant linkage disequilibrium was observed between any pair of loci after Bonferroni correction.In cross-species amplification,five flatfish species(Paralichthys lethostigma,Verasper moseri,platichthys stellatus,Hippoglossoides dubius and Cynoglossus semilaevis) showed at least one polymorphic locus.These polymorphic microsatellite loci should prove useful for population analysis of turbot and other related species.     

Induced nest spawning and artificial hatching of the fertilized eggs of mudskipper, Boleophthalmus pectinirostris

In this study, nest spawning was successfully induced by exogenous hormone injections and seawater flow stimulation, and optimum condition for hatching fertilized eggs of burrow fish mudskipper,Boleophthalmus pectinirostris, was searched. Apart from spawning inside the nests, females also spawned outside the nests. The percentages of spawned nests were 8.0% to 24.2%. Most eggs were observed adhered to the inner wall of the top half of the nest. Fertilization rates of the nest-spawned eggs varied from 17.3% to 80.8% Females could spawn after being artificially confined inside the‘nests with males at ratios of 1:1 or 1:2, but the spawned eggs were not fertilized. Mean hatching rates of artificially fertilized eggs incubated in round plastic buckets were 32.7%-70.6%, and in the net cages, were 4.2%-20.5%, respectively. Mean hatching rates of nestfertilized eggs incubated in the round plastic buckets were 33.6%-76.3%, and in the net cages, were 5.9%-25.2%.Results showed that round bucket incubation was the best way for hatching fertilized eggs of mudskipper.Keeping the hatching seawater flowing is an important way for increasing the hatching rates of the mudskipper fertilized eggs.     

STUDY ON MIXIS POTENTIAL OF ROTIFER RESTING EGGS（ BRACHIONUS PLICATILIS ） WITH DIFFERENT COLLECTION TIMES AND DIFFERENT PRESERVATION PERIODS

The present study investigated the possible changes in the mixis potential of rotifer resting eggs produced by a single stock of Brachionus plicatilis and collected and preserved annually from 1985 - 1998. Several clones derived from each batch of resting eggs were cultured under the same conditions for 21 days. The percentage of clones appearing resting eggs and the average yield of resting eggs produced from each clone were recorded and statistically analyzed to find the differences between the mixis potential of those resting egg batches. Results showed that different batches of resting eggs had different mictic levels among their descendent clones; but no regular relationship was found between the mixis potential of resting eggs and their collection times/preservation periods. Several internal and external factors that might affect the mixis potential of resting eggs were discussed.     

Induced nest spawning and artificial hatching of the fertilized eggs of mudskipper, Boleophthalmus pectinirostris

In this study, nest spawning was successfully induced by exogenous hormone injections and seawater flow stimulation, and optimum condition for hatching fertilized eggs of burrow fish mudskipper,Boleophthalmus pectinirostris, was searched. Apart from spawning inside the nests, females also spawned outside the nests. The percentages of spawned nests were 8.0% to 24.2%. Most eggs were observed adhered to the inner wall of the top half of the nest. Fertilization rates of the nest-spawned eggs varied from 17.3% to 80.8%. Females could spawn after being artificially confined inside the nests with males at ratios of 1∶1 or 1∶2, but the spawned eggs were not fertilized. Mean hatching rates of artificially fertilized eggs incubated in round plastic buckets were 32.7%–70.6%, and in the net cages, were 4.2%–20.5%, respectively. Mean hatching rates of nest-fertilized eggs incubated in the round plastic buckets were 33.6%–76.3%, and in the net cages, were 5.9%–25.2%. Results showed that round bucket incubation was the best way for hatching fertilized eggs of mudskipper. Keeping the hatching seawater flowing is an important way for increasing the hatching rates of the mudskipper fertilized eggs. Supported by the NSFC (No. 30170739), and also supported by the Provincial Natural Science Foundation of Fujian Province (No. B0210003).     

STUDY ON MIXIS POTENTIAL OF ROTIFER RESTING EGGS ( BRACHIONUS PLICATILIS ) WITH DIFFERENT COLLECTION TIMES AND DIFFERENT PRESERVATION PERIODS

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Breeding and mass scale rearing of clownfish Amphiprion percula: feeding and rearing in brackishwater

Breeding and mass scale larval rearing of clownfish Amphiprion percula is very limited in brackishwater. We designed an indoor program of A. percula culture in brackishwater with a salinity of 24±1, during which the impacts of feed type, water temperature, and light intensity, on the efficiency of its reproduction, were revealed. The fish were accommodated along with sea anemones in fibre glass tanks to determine the influence of brooder diet on breeding efficiency. Higher reproductive efficiency [number of eggs laid (276 22.3 eggs)] was observed when fish were fed live Acetes sp. rather than clam (204 16.4 eggs), trash fish (155 12 eggs) and formulated feed (110 10 eggs). The spawning rate was increased during September and October (water temperature, 28.74 0.55°C) on average of 2.4 spawning per month; and low spawning rate was in January (water temperature, 24.55 0.45°C) on average of 1 spawning per month. Among three light intensities (100, 500, and 900 lx) set to evaluate larval survival rate, larvae showed the highest survival rate (65.5%) at 900 lx. The breeding method specifically in brackishwater developed in the present study is a new approach, will help the people from the regions of estuary and backwater to enhance their livelihood and it will lead to reduce the exploitation from the wild habitat.     

BIOCHEMICAL CHANGES DURING DEVELOPMENT OF EGGS AND YOLK-SAC LARVAE OF HERRING AND PLAICE

Changes in quantities of water, sodium, potassium, lipid and protein were compared in developing eggs and yolk-sac larvae of herring dupes harengus L., a species with demersal eggs, and plaice Pleuroncctcs platessa L., a species with pelagic eggs. The principal difference between the two species was the occurrence in herring, but not in plaice of considerable increases in water content and in one or both of the above ions at three distinct stages: at fertilization,during the middle stage of egg development, and in the days immediately after hatching. Newly hatched larvae of the two species differed greatly in water content because of the difference in mass and water content of the yolk, not in the water content of the rest of the body. In herring, there were increases in sodium and potassium which coincided broadly with the increase in water content. These differences are related to the gradual acquisition of buoyancy by herring during this period, comparable with the buoyancy conferred on plaice eggs a     

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 …     

The reaction time of organ-forming substance in goldfish EGG and its relationship with mesodermal formation

Fertilized goldfish eggs were dechorionated with a pair of forceps and were cut off along or a little above the equator into animal and vegetative parts at desired stages with a glass needle or ligated into two connected fragments before cleavage with baby hair loop. Some of the ligated eggs were detached by further fastening soon after ligation, and some released later at different stages (2-cell, 16-cell, 128-cell, 512-cell, mid-blastula) to let the organ-forming substance (OFS) enter the blastoderm. The cholinesterase (ChE) in the resulting embryos was assayed. The results are as follows. 1. All the 142 embryos developed from the animal hemispheres cut off or ligated off before cleavage gave rise to hyperblastula in which no ChE activity was observed. 2. All 50 embryos obtained from animal halves isolated at the 8-cell stage produced ChE. 3. Embryos developed from the eggs released before the 512-cell stage formed ChE, but the later the releasing of the hair knots, the smaller the number of ChE-producing embryos. 4. After the 512-cell stage (excluding this stage), neither ChE nor tissue differentiation occurred in the embryos developed from the unfastened eggs though their OFS flow was set free. Since ChE is thought to be a muscle-specific enzyme in the early developmental stage, it is concluded that the OFS in goldfish egg appears to be indispensable for the establishment of the mesoderm. Contribution No. 1507 from the Institute of Oceanology, Academia Sinica     

波纹龙虾胚胎的离体培养及发育观察

对波纹龙虾不同发育时期的胚胎进行离体培养和显微观察。结果表明,初始培育的离体胚胎愈接近孵化期,其孵化率愈高(最高达80.0%);波纹龙虾胚胎发育经历受精卵、卵裂期、囊胚期、原肠期、中眼色素形成期、复眼色素形成期、心跳期、破膜前期和出膜期;胚胎在发育过程中颜色变化:橙红→深橙红→砖红→灰白→接近透明。     

STUDY ON EMBRYONIC DEVELOPMENT AND EARLY GROWTH OF TRIPLOID AND GYNOGENETIC DIPLOID LEFI—EYED FLOUNDER, PARALICHTHYS OLIVACEUS （T. et S. ）

The early effects of chromosomal manipulation of eggs and sperm on the yields of trip-loid and gynogenefic diploid larvae of Paralichthys olivaceus were investigated. Triploidy was achieved by cold shocking fen.ilized eggs at 0 - 2℃ for 45 minutes duration 5 minutes after fen.ilization, and the in-duced triploidy rates were 31.2% - 50% and the relative hatching rates were 53.3% - 99%. Gynnge-aetic diploids were obtained when eggs were inseminated with irradiated sperm and cold shocked at 0 -2℃ for 45 minutes duration 5 minutes after fertihzation. The induced gynogenetic diploid rates and the relative hatching rates were 94 % - 96 % and 48.5 % - 68.5 % respectively. The embryonic development of the triploid experimental group and of the gynogenetic diploid experimental group was delayed at first compared with the control group. But from the gastrula stage, it was not delayed anymore. There were no significant differences in the growth of the triploid experimental group larvae and the control group larvae, and in the growth of the gynogenetic diploid experimental group larvae and the control group larvae ac-cording to Student‘s t-test (α = 0.05). The relationship between the early growth of the triploid experi-mental group larvae and that of gynogenetic diploid experimental group larvae was also studied.     

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.     

Development of inter-family nuclear transplant embryos by transplanting the nuclei from the loach blastulae into the non-enucleated zebrafish eggs

The developmental fate of the pronuclei in recombined embryos obtained by transplanting the donor nuclei into the non-enucleated eggs remains controversial in the case of fish.In the present study,the nuclei from the loach blastulae were transplanted into non-enucleated zebrafish eggs,the resulting 9 inter-family nuclear transplant embryos developed to larval stages,Although the development timing of the nuclear transplants resembled that of zebrafish,chromosome examination revealed that most of the recombined embryos were diploids with karyotype characteristic of loach,which was also proved by RAPD analysis.Moreover,3 out of the 9 larval fish formed barb rudiments specific to loach.It was therefore concluded that the nuclear transplant larval fish were inter-family nucleo-cytoplasmic hybrids;and that only the donor nuclei were involved in the development of the nuclear transplant embryos,while the pronuclei in the non-enucleated eggs were likely automatically eliminated during the development.     

Cytoplasmic regionalization in starfish oocyte occurrence and localization of cytoplasmic determinants responsible for the formation of archenteron and primary mesenchyme in starfish (asterias amurensis) oocytes

Starfish oocytes with intact germinal vesicles (GVs) were cut along desired planes with glass needles or ligated using silk thread loops into two parts and allowed to mature in vitro, and inseminated. The experimental results showed that (1) only the parts with GVs or partial GV contents (PGVCs) cleaved, those without any GV materials did not; but nucleated and non-nucleated fragments cut from mature eggs were able to divide; (2) the development of animal parts of oocytes containing GVs or PGVCs was like that of animal fragments of matured oocytes with female pronuclei; most of them gave rise to permanent blastulae, and just a few formed ectodermal vesicles with a little primary mesenchyme; (3) a large part of vegetal fragments with GVs or PGVCs, and the vegetal parts of mature eggs without female pronuclei developed into small but normal embryos; (4) the fragments containing GVs or PGVCs obtained from the oocytes along a plane parallel to the animal-vegetal (A-V) axis developed as normally as the halves (with or without female pronuclei) severed from mature eggs along the same axis. Based on the data above, it was concluded that (1) the non-chromatin materials in the oocyte GVs are indispensable for successful fertilization and cleavage of starfish eggs; (2) some factor (s) located asymmetrically in the vegetal hemispheres of starfish oocytes is (are) responsible for formation of the archenteron and primary mesenchyme. It is evident from the above findings that the oocyte cytoplasm of the starfish had already regionalized before the GV break-down. Contribution No. 1722 from the Institute of Oceanology, Academia Sinica     

GROWTH, REPRODUCTION & POPULATION STRUCTURE OF THE FRESHWATER CRAB SINOPOTAMON YANG TSEKIENSE BOTT, 1967, FROM ZHEJIANG, CHINA

Monthly investigatiom were made on the population of Chinese freshwater crab, Sinopotamon yangteskiense Bott, 1967 from April, 1984 to Match, 1985. The data on 4413 specimens show that the growth was affected mainly by temperature. During the April to November growth period, the crabs' major development occured from June through October. One year was required for a fine white oocyte to develop into a mature egg. The reproduction period was June-October. Females bearing eggs were taken from June-August, and crabs with young were found from July-October. The females reproduced once a year but could for more than one year. The number of eggs carried by a female varied greatly according to the size of the crab, ranging from 30 to 100 eggs. New-bom crabs become mature after 1-2 yeats. The sex ratio was approximately 1:1 in the overall population. However, the larger crabs are predominantly male. The age distribution of S. yangtsekinese was estimated from size frequency histograms. There were more adult crabs     

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.     

鞍带石斑鱼人工繁殖及胚胎发育研究

为建立鞍带石斑鱼(Epinephelus lanceolatus)人工繁殖技术,研究了鞍带石斑鱼亲鱼培育、催产及胚胎发育过程。根据性腺检查及催产结果,判定鞍带石斑鱼在广东的繁殖季节为每年的7-9月份,产卵水温在28~31℃。使用10~12尾雌鱼和3尾雄鱼搭配进行催产实验,亲鱼未出现发情和追尾现象,虽能产卵但均未受精,通过人工授精可得受精卵。对鞍带石斑鱼胚胎发育进行了观察,详细描述从受精卵到初孵仔鱼的28个具体发育时期的形态特征和发育时间,结果表明,将鞍带石斑鱼胚胎发育划分为卵裂期、囊胚期、原肠胚期、神经胚期和器官形成期。在水温(27±0.5)℃、盐度31.0、pH 7.8的海水中,鞍带石斑鱼胚胎历时25 h 40 min完成整个胚胎发育孵化出膜。     

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     

罗非鱼开口饵料的初步研究

研究了配合饵料、轮虫、蛋黄、轮虫+人工配合饵料(3～12日龄投喂轮虫,13日龄起投喂配合饵料)等4种开口饵料对奥尼罗非鱼仔鱼生长、发育和存活影响。结果表明,1)投喂不同饵料对奥尼罗非鱼仔鱼生长具有显著影响(P<0.05),轮虫+配合饵料组生长较快,绝对增重率和特定增重率分别为0.011g/d和17.18%d-1;蛋黄组生长最慢,绝对增重率和特定增重率与其他各组差异显著(P<0.05)。2)轮虫+配合饵料与轮虫组的仔鱼成活率较高,分别为90.3%和89.7%,2组差异不显著(P>0.05),且仔鱼发育较好,大部分个体进入稚鱼阶段;蛋黄组成活率最低,只有40.7%,个体发育较为缓慢,与其他各组差异显著(P<0.05)。可见,投喂鲜活的天然饵料(轮虫)+配合饵料是罗非鱼苗种培育的最佳开口饵料。     

Growth,reproduction & population structure of the freshwater crabSinopotamon yangtsekiense bott, 1967, from Zhejiang,China

Monthly investigations were mae on the population of Chinese freshwater crab,Sinopotamon yangtsekiense Bott, 1967 from April, 1984 to March, 1985. The data on 4413 specimens show that the growth was affected mainly by temperature. During the April to November growth period, the crabs' major development occurred from June through October. One year was required for a fine white oocyte to develop into a mature egg. The reproduction period was June–October. Females bearing eggs were taken from June–August, and crabs with young were found from July–October. The females reproduced once a year but could for more than one year. The number of eggs carried by a female varied greatly according to the size of the crab, ranging from 30 to 100 eggs. New-born crabs become mature after 1–2 years. The sex ratio was approximately 1∶1 in the overall population. However, the larger crabs are predominantly male. The age distribution ofS. yangtsekinese was estimated from size frequency histograms. There were more adult crabs (over 70%) from June to October and more immature crabs (over 50%) from November to May.