七带石斑鱼和云纹石斑鱼幼鱼在封闭循环水条件下的生长特性

观测研究了七带石斑鱼(Epinephelus septemfasciatus)幼鱼和云纹石斑鱼(Epinephelus moara)幼鱼在封闭式循环养殖系统中的生长特性,用SPSS 17.0软件中的Curve Estimation对相关数据进行模型分析与参数估计。结果表明,经过122 d的养殖,七带石斑鱼幼鱼平均体质量由(114.836±25.343)g增加到(213.861±38.604)g,相对增长率为0.707%,全长(TL)与养殖时间(t)的函数关系式为TL=-0.006t3+1.622t+13.954,体质量(W)与体长(BL)的关系式为W=0.436BL2.055;云纹石斑鱼幼鱼平均体质量由(79.620±13.007)g增加到(238.086±46.307)g,相对增长率为1.631%,全长(TL)与养殖时间(t)的函数关系式为TL=-0.013t2+2.008t+11.540,体质量(W)与体长(BL)的关系式为W=0.018BL3.083。两种幼鱼丰满度生长差异不显著(P0.05),都保持在2.2-3.4之间。     

Dietary protein requirement of juvenile kelp grouper (Epinephelus moara)

Dietary protein requirement of juvenile kelp grouper Epinephelus moara was investigated through a feeding trial. Experimental diets with graded crude protein (CP) levels (33.01%, 38.54%, 45.21%, 50.71%, 56.10% and 63.09% of dry matter respectively) were formulated. Six triplicate groups of fish (20 individuals per replicate with initial mean weight 6.00 g) were fed with each diet for 8 weeks. Best growth performance of fish was detected in 56.10% CP diet. The specific growth rate (SGR) significantly elevated with increasing dietary CP level to 50.71%, but there was no significant difference thereafter (p < .05). The feed conversion ratio (FCR) decreased significantly with dietary CP levels from 33.01% to 56.10% (p < .05). Glucose (GLU) and total protein (TP) concentrations in plasma had an increasing trend with dietary protein increasing. In the 33.01% CP group, plasma triglyceride (TG) content was significantly higher (1.67 mmol/L) than that in other dietary treatments (0.65–1.14 mmol/L). The lowest alanine transaminase (ALT) activity was observed in the 56.10% CP group (163.16 U/L). Crude lipid content in the muscle and liver was significantly elevated with increasing dietary protein levels (p < .05). The glycogen content in the liver decreased significantly as CP levels increased (p < .05). The fish fed diet with higher CP level (56.10% and 63.09%) had significantly higher energy retention (ER) and lipid retention (LR) than other treatments. Based on the broken‐line regression analysis of SGR and FCR, the optimal dietary protein requirement for juvenile kelp grouper is 54.61%–56.22%.     

鞍带石斑鱼Epinephelus lanceolatus (Bloch)繁殖生物学的初步研究

本文对鞍带石斑鱼的繁殖生物学特性进行了初步研究，该鱼在台湾已可进行商业化育苗生产，但在广东沿海还有待摸索。     

Artificial sex reversal of white grouper (Epinephelus aeneus) utilizing aromatase inhibitor (Fadrozole)

The white grouper is a desirable aquaculture species that adapts to captivity, grows well and commands a high market price. However, little is known about reproductive biology or control of sex reversal of this protogynous hermaphrodite. In this study, female white groupers were implanted with one dose of 17α‐methyltestosterone (10 mg/kg body weight [BW], MT) and two doses of aromatase inhibitor, fadrozole (1 and 3 mg/kg BW, FD1 and FD3) once a month for 4 months (April–July). At the start of the study, the fish had gonads full of oocytes compared to the end of the experiment when the control group mature oocytes compared to the experimental groups MT, FD1 and FD3 that exhibited different stages of testicular tissue. Plasma levels of testosterone were significantly highest in the FD3 group and the highest 11‐Ketotestosterone levels were observed in the MT group. Plasma levels of oestradiol (E₂) were significantly lower in the FD implanted groups, compared to initial individuals and control groups. The use of aromatase inhibitor, FD for sex reversal both gives further insight into the mechanisms controlling sex differentiation and provides an alternative to steroid treatment.     

七带石斑鱼染色体核型研究

采用PHA体内直接注射法制备了七带石斑鱼(Epinephelus septemfasciatus)头肾组织染色体标本并分析其核型。结果表明,七带石斑鱼二倍体染色体数为48,24对染色体均为端部着丝粒染色体,其染色体臂数(NF)为48,核型公式为:2n=48t,NF=48。未发现与性别相关的异型染色体,第24对染色体长度明显小于其他染色体。通过与其他22种石斑鱼染色体核型进行比较,发现七带石斑鱼具有石斑鱼属鱼类的原始核型特征,属于石斑鱼属鱼类的原始类群。     

Induced sex reversal of dusky grouper, Epinephelus marginatus (Lowe)

The present paper describes sex reversal in dusky grouper, Epinephelus marginatus (Lowe). Over a 4-month feeding period, 5 mg kg^?1 of the male hormone 17-α methyltestosterone was combined with frozen fish as feed. After 2.5 months of treatment, the gonads of all six fish treated in the experiment presented tissues with oocytes and spermatogonia, and after 3 months, there were only a few remnants of oogonial tissue left in the gonads. All fish in the experiment gave sperm of varying quality after 4 months of the trial. The quantity of the hormone administered to the fish over these 4 months was 89-113 mg kg^?1. Spermatozoid motility varied from 95% to 40%, and lasted for about one hour in sea water. Using the combined sperm of three males, fertilization ranged from 50% to 95%. Fertilized eggs and hatched larvae continued to develop normally.     

鞍带石斑鱼Epinephelus lanceolatus(Bloch)中间培育技术的初步研究

将体长2.4～3.00锄,平均体长2.64 cm;体重2.37～3.16 g,平均体重2.68 g的鞍带石斑鱼鱼苗在水温17.扣24～6℃、海水盐度31.2条件下进行室外水泥池培育.采取逐渐添加淡水降低盐度至18～19;以鱼体重4%～6%日投喂量投喂用鱼浆或鲜虾浆与幼鳗粉料混合制成的湿性饲料的方式.经过52 d的培育,鱼苗体长增至4.7～6.8 cm,平均体长增长3.12 era/尾,增长率121.44%;体重增至5.73～8.64g,平均体重增重4.84 g/尾,增重率180.6%.培育存活率97.4%.     

Mass mortalities associated with viral nervous necrosis (VNN) disease in two species of hatchery-reared grouper, Epinephelus fuscogutatus and Epinephelus akaara (Temminck & Schlegel)

Mass mortalities of hatchery-reared juvenile groupers have occurred in southern Taiwan. The diseased fish swam in a darting, corkscrew fashion. Light microscopy revealed vacuolation in the brain tissue. Electron microscopy showed numerous non-enveloped, cytoplasmic viral particles (20–25 nm in diameter) in the brain cells, and many virions were enclosed in the membrane-bound organelles of the cells. Two structural proteins of the purified grouper virus, with molecular weights of 44 and 43 kDa, were revealed by SDS-PAGE. Moreover, the results of RT-PCR and nested PCR diagnosis using primers specific to the T2 and T4 target segments of striped jack nervous necrosis virus (SJNNV) RNA2 genes suggest that this virus is a fish nodavirus, and is designated as GNNV 9410 strain (grouper nervous necrosis virus strain 9410). This is the first case report of viral nervous necrosis among marine fish in Taiwan.     

点带石斑鱼Epinephelelus malabaricus(Schneider)人工育苗技术的初步研究

通过对点带石斑鱼受精卵孵化、初孵仔鱼不同开口饵料的选择及后期仔鱼阶段在饵料、水质调控等方面的试验,探索了点带石斑鱼人工育苗技术。结果表明,采用牡蛎受精卵及担轮幼虫为初孵仔鱼的开口饵料比用BP、虾片作初孵仔鱼开口饵料的育苗成活率提高432.16%;后期仔鱼至稚、幼鱼阶段育苗池水质的优、劣,对育苗成活率关系密切;经过53d共培育出平均全长2.86cm的幼鱼4.91万尾,平均育苗成活率4.09%。     

Cryopreservation of sperm from natural and sex-reversed orange-spotted grouper (Epinephelus coioides)

The shortage of males and/or sperm has been an impediment to the aquaculture of orange-spotted grouper (Epinephelus coioides). This study reversed orange-spotted grouper females into males using hormone implants. A cryopreservation protocol for sperm was developed using normal males, and then using similar procedures the cryopreservation of sperm from sex-reversed males was compared. Immature, young and mature female fish were injected with 4 mg kg⁻¹ BW 17α methyltestosterone as implants and the gonad development stage was monitored over a 120-day period. All treated females converted into functional males within 120 days of the experimental period. Younger females (2Y) were all males within 30 days, although not all were capable of fertilizing fresh ova until day 60. The time after injection to sex reversal in immature fish was 50% shorter than in older females. Postthaw fertilization (81%, 82%) and hatching (45%, 47%) of cryopreserved sperm from natural males were the highest in trehalose (15–20%) with 150 mmol NaCl treatment; however, it was less than the control (89% fertilization and 69% hatch). There was no difference in the postthaw fertilization and the hatch percentages between sex-reversed male sperm (64% and 46% respectively) compared with natural male sperm (59% and 49%). The findings of this study suggest the potential use of sex-reversed males and cryopreserved sperm for commercial production of orange-spotted grouper seed for aquaculture.     

Characterization of triploid hybrid groupers from interspecies hybridization (Epinephelus coioides ♀ × Epinephelus lanceolatus ♂)

Interspecies hybridization is widely used in aquaculture as a beneficial strategy. Diploid and triploid hybrids have been detected from the interspecies hybridization of Epinephelus coioides ♀ × Epinephelus lanceolatus ♂. This is the first report of triploidization through hybridization in grouper. Confirmation has been obtained through flow cytometry, karyotyping and erythrocyte nuclei measurement. The chromosome numbers of E. coioides, E. lanceolatus, diploid hybrid grouper are 48 and triploid hybrid grouper are 72. Measurements of erythrocyte nuclei indicate that triploid fish have a larger nuclear surface than the diploid groupers, and the average ratio of triploid to diploid surface area is 1.59. During the first 1.5 years, triploid hybrid groupers grow faster than diploid hybrid groupers or either parent species. The average growth rate of triploid hybrids is 1.61 times greater than that of diploid hybrids at 6 months of age and 1.43 times greater at 18 months of age. The triploid hybrid groupers are inferior in gonadal development, with no primary‐growth‐stage oocytes appearing in the gonads at 18 months of age. Morphological studies indicate that triploid hybrid groupers have distinctive differences in snout length, eye diameter, body trunk shape, and tail shape development compared with diploid hybrid groupers. Triploid hybrid groupers have an advantage in growth ability, and artificial breeding of triploid groupers might be of great potential use in the grouper aquaculture industry.     

Ulcerative dermatitis in wild dusky grouper Epinephelus marginatus (Lowe) from Libyan waters

In the period 2013–2015, wild dusky grouper, Epinephelus marginatus (Lowe), caught in Libyan coastal waters and ranging in size from 42 to 92 cm in total length, were observed to have distinctive skin lesions of unknown aetiology. Histopathologically, the lesions comprised a multifocal, unilateral or bilateral dermatitis, involving the epidermis, superficial dermis and scale pockets, and sometimes, in severe cases, the hypodermis. Severe lesions had marked epidermal spongiosis progressing to ulceration. Healing was observed in some fish. Bacteria and fungi could be isolated from severe lesions, although they were not seen histopathologically in early‐stage lesions. By contrast, metazoan parasite eggs were observed in the dermis and epidermis of some fish with mild and moderate dermatitis. Unidentified gravid digenean trematode parasites carrying similar eggs were also seen within the blood vessels of the deep and superficial dermis. The cause of this distinctive condition, termed dusky grouper dermatitis (DGD), and its potential impact upon already threatened Mediterranean wild dusky grouper populations and upon cultured grouper more widely have yet to be established.     

Preliminary observations of chilled and deep-frozen storage of grouper (Epinephelus tauvina) sperm

Trials of chilled (5–10° C) and cryogenic storage of grouper sperm revealed that sperm suspended in two different solutions containing 10% dimethyl sulfoxide (DMSO) were active after 2 days of chilled and deep-frozen storage, whereas those suspended in the same solutions containing 10% glycerol were not. Sperm suspended in the 10% DMSO sulutions were more active after chilled storage than were those in undiluted milt under the same conditions.     

鞍带石斑鱼繁育群体遗传多样性分析

鞍带石斑鱼作为最大型的石斑鱼,生长速度快,有明显的生长优势,在石斑鱼的产业发展中起到举足轻重的作用。为了解人工养殖和选育活动对鞍带石斑鱼遗传多样性的影响,本文采用微卫星分子标记技术,对广东、海南和福建三个省份共五个代表性采集点的鞍带石斑鱼繁育群体的遗传变异信息进行了研究。群体内遗传多样性分析显示,5个群体等位基因(Na)的平均数目为7.326(6.375-8.380),观测杂合度(Ho)平均值为0.711(0.625-0.775),期望杂合度(He)平均值为0.705(0.684-0.734),多态信息含量(PIC)平均值为0.659(0.633-0.693)。其中,来自福建厦门翔安区的鞍带石斑鱼繁育群体遗传多样性最高。分子方差分析(AMOVA)结果显示,5.36%的遗传变异来自群体间,95.45%来自所有个体间。群体间遗传分化指数(Fst)及遗传距离结果显示,GC和CP群体聚为一支,再与AT群体聚为一支,再与XA群体距为一支,HL群体为独立一支。通过系统进化树分析显示,鞍带石斑鱼繁育群体交叉在一起,没有形成明显的地理格局分布。总而言之,这三省五地的鞍带石斑鱼繁育群体遗传多样性较高,没有明显的驯化迹象。整体研究表明,鞍带石斑鱼繁育群体仍具有较高的遗传多样性,品种受亲本近交影响而出现衰退的可能性不高,人工繁育技术的不完善及养殖管理不规范可能是导致品种病害频发及养殖成活率低的原因。本研究为鞍带石斑鱼种质评价和人工选育提供理论依据。     

石斑鱼循环水养殖系统微生物群落结构

通过16S rRNA基因片段高通量测序研究了褐点石斑鱼(Epinephelus fuscoguttatus)和东星斑(Plectropomus leopardus)循环水养殖系统水体细菌种群结构。结果显示石斑鱼循环水养殖系统中优势细菌类群为变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、蓝藻门(Cyanobacteria)、梭杆菌门(Fusobacteria)、厚壁菌门(Firmicutes)和硝化螺旋菌门(Nitrospira)。其中养殖塘、固液分离池、沉淀池和蛋白分离池中主要优势细菌为γ-变形菌纲(Gammaproteobacteria),紫外消毒池和补氧池中则以a-变形菌纲(Alphaproteobacteria)为主,而生物滤池中两者比例接近,均为优势种群。从养殖塘到补氧池细菌多样性指数先降低后升高,生物滤池中达到最高值,之后再次下降至紫外消毒池中达到最低值,补氧池中有所回升。PCoA分析和聚类分析结果表明,养殖水在紫外消毒前后其细菌群落组成有着明显的差异。水质理化指标检测表明,经过净化处理后,循环系统的养殖水溶解氧含量上升,氨氮和亚硝酸盐含量下降并维持在较低的浓度。环境因子与细菌群落结构相关性分析结果表明,磷酸盐、pH、溶解氧和温度等指标可能对细菌群落结构影响相对较大,但未发现两者间有很显著的相关性,这可能与实验样本较少有关。     

石斑鱼性逆转研究现状

石斑鱼(Epinephelus)广泛分布于热带、亚热带暖水海域,为暖水性礁栖鱼类[1]。世界上有100余种,我国已记录的有45种,从浙江到海南岛、北部湾直至南沙群岛的海域均有分布[2-4]。本属鱼肉质细嫩,味道鲜美,是名贵的海水经济鱼类。近几年来,由于自然海区钓捕过度,石斑鱼资源严重衰退     

Growth performance and disease resistance against Vibrio vulnificus infection of novel hybrid grouper (Epinephelus lanceolatus × Epinephelus fuscoguttatus)

Groupers are economically important for aquaculture in Thailand. A novel hybrid grouper (Epinephelus lanceolatus × Epinephelus fuscoguttatus) has been successful cross‐bred; therefore, the present work aimed to assess the hybrid's traits. The growth performance, strength and tolerance to a pathogenic bacterial infection of this hybrid were compared with its parent species, tiger grouper and giant grouper. The results of all measured growth parameters indicated that the hybrid strain grew fastest followed by giant and tiger grouper respectively. The expressions of the growth‐related genes, insulin‐like growth factor (IGF) I and II, were also analysed in fish muscle and liver which are the main target organs in fish growth regulation. Among tested species, similar expression patterns of IGF‐I and IGF‐II were detected in both organs. The levels of these genes in liver and muscle of hybrid and giant grouper were higher than those of tiger grouper comparable with the growth manner. After challenge with Vibrio vulnificus, the immunological parameters, clearance time of Vibrio in haemolymph and survival was measured to verify the fish immunity. Leucocyte number, lysozyme activity and the ability to eliminate the pathogen were very high in hybrid and giant grouper while these parameters were lower in tiger grouper. Correspondingly, the mortality rate of tiger grouper was higher than others and % survival at the end of observation time (15 days post challenge) was lowest in infected tiger grouper. Altogether, the results suggested that the hybrid grouper has desirable traits that will improve cultured grouper.     

日本东京湾云纹石斑鱼染色体核型研究

采用PHA体内直接注射法制备了云纹石斑鱼(Epinephelus moara TemminckSchlegel1842)东京湾群体头肾组织染色体标本并分析其核型。结果显示,其东京湾群体二倍体染色体数为48,其中,亚中部着丝粒3对;其余21对染色体为端部着丝粒染色体,其染色体臂数NF为54,核型公式为:2n=48,6sm+42t,NF=54;第24对染色体的短臂的形态具有多态性。该鱼染色体臂数高于石斑鱼类的原始核型类群,属于石斑鱼属的特化类群。云纹石斑鱼日本东京湾群体与厦门群体染色体核型存在显著差异,东京湾群体比厦门群体多1对亚中部着丝粒染色体,可能是长期隔离导致染色体重组进化形成的。结果表明,云纹石斑鱼不同地理群体间存在丰富的遗传差异,可利用不同地理群体间的种内杂交优势改良云纹石斑鱼种质。     

Vibrio harveyi (VirB11) recombinant vaccine development against vibriosis in orange‐spotted grouper (Epinephelus coioides)

Despite significant improvements in aquaculture to compensate wild catch, disease organisms have thrived in limiting its national and global potential. Using antibiotics, in a bid to remedy the havoc, has given rise to complications, attracting attention to disease prevention by immune enhancement against diseases. Grouper production has been inhibited for the threats of bacterial infection, particularly of Vibrio origin. Considering the rise in vibriosis cases, improved vaccines are necessary; moreover, recombinant vaccines, the choice for trial in the present experiment have been effective and more specific in improving immunity. The current work deals with grouper immune system enhancement with a recombinant vaccine developed from VirB11 gene in Vibrio harveyi. VirB11 was cloned in V. harveyi for recombinant vaccine development against vibriosis in orange‐spotted grouper (Epinephelus coioides). As indicated by the results, recombinant VirB11 protein showed effectiveness in conferring protection against vibriosis with observable specific antibody response in enzyme‐linked immunosorbent assay (ELISA) analysis; a significant increase (p < 0.05) in antibody levels was observed after a week and after 8 weeks post‐vaccination. From the weeks post‐vaccination, log2 (antibody titres) in the sera of vaccinated groups reached a peak of 14.2 at week 5 in the vaccinated group in comparison with a peak of approximately 5 and 2 in adjuvant and PBS controls. As indicated by the challenge results, 90% relative survival was observed in vaccinated group and 13% relative survival in control group I (adjuvant control). The cumulative performance of protein concludes VirB11 commendable for recombinant vaccine development.