千年笛鲷幼鱼耗氧率的研究

千年笛鲷幼鱼的耗氧量随幼鱼体重的增加而增加,耗氧量与体重的关系式为Y=0．756 0．513X。千年笛鲷幼鱼的耗氧率随幼鱼体重的增加而下降,耗氧率与体重的关系式为Y=1246．430X~(-0.036)。幼鱼在遮光条件下的耗氧率比在自然光照条件下要低15．362%～31．675%。在低盐度水环境下幼鱼的耗氧率较高,随着盐度的增加,其耗氧率降低。随着饥饿程度的加深,千年笛鲷幼鱼的代谢水平呈梯度下降。在盐度20和28时,千年笛鲷幼鱼的窒息点分别为0．93和1．17 mg·L~(-1)。     

红鳍笛鲷人工繁殖及育苗技术研究

利用海水土池或网箱养殖3龄以上的红鳍笛鲷成鱼,于催产前二个月进行强化培育.在水温达到18～24℃时,用HCG和LRH-A2或LRH-A3进行催产,混合或单一使用,剂量视亲鱼成熟度而定.受精卵在盐度28～30.2,水温18～22℃,pH值8.2的环境中经15～16h孵化.开口仔鱼在土池水温26.5～30.2℃,盐度18～24,pH值7.8～8.8的条件下,经26～30d培育,完成变态发育进入幼鱼期.     

菲胁迫对红鳍笛鲷急、慢性毒性效应的研究

为了解海洋菲污染对海洋水产经济鱼类的毒性及致毒机理,在实验室条件下采用半静态毒性实验研究了菲对红鳍笛鲷的96 h急性毒性,同时分析和比较了不同浓度(10.0、50.0、250.0μg/L)菲胁迫96 h后红鳍笛鲷肝脏、鳃中超氧化物歧化酶(SOD)活力,丙二醛(MDA)含量以及脑组织中乙酰胆碱脂酶(AChE)活力的变化。结果表明,菲对红鳍笛鲷幼鱼的24、48和96 h半致死浓度(LC50)分别为4.65、3.46和3.17 mg/L,安全浓度为0.317 mg/L。在整个胁迫过程中,低浓度(10.0μg/L)菲可诱导红鳍笛鲷肝脏和鳃组织SOD活力显著性升高(P<0.05);随着浓度升高,50.0和250.0μg/L浓度组肝脏SOD活力呈抑制-诱导的波动变化,鳃SOD活力的变化则呈抑制-诱导-抑制的趋势。随着菲曝露时间延长,各浓度组红鳍笛鲷肝脏和鳃组织的MDA含量明显升高;脑组织中AChE活力表现为先升高后降低的的趋势。结果提示,菲对红鳍笛鲷具有很强的毒性,可在96 h内通过氧化损伤途径对机体产生毒性作用,鉴于SOD、MDA、AChE指标对菲的高度敏感特点,可以用其作为生物标志物来指示多环芳烃类污染物对水生生物的...     

Cloning and expression of the gene encoding an extracellular alkaline serine protease from Vibrio alginolyticus strain HY9901, the causative agent of vibriosis in Lutjanus erythopterus (Bloch)

A 750-bp internal fragment of the alkaline serine protease gene (asp) from the Vibrio alginolyticus strain HY9901 was amplified by polymerase chain reaction (PCR). The flanking sequences of the 5'- and 3'- ends of the asp gene were characterized by reverse and nested PCR. Sequence analysis showed that the asp gene contained an 1893-bp ORF encoding 630 amino acids. The deduced amino acid sequence of the ASP (alkaline serine protease) precursor showed significant homology with several bacterial alkaline serine proteases. Expression of the asp gene in Escherichia coli and activity tests of the ASP indicated that the N-signal peptide of the ASP precursor was essential to autocatalyse and fold correctly the enzyme to obtain activity. The purified ASP was lethal for Lutjanus erythopterus with an LD(50) of 0.25 microg protein g(-1) body weight.     

千年笛鲷幼鱼的饥饿和补偿生长

研究了在22.5～31.9 ℃条件下,千年笛鲷幼鱼在不同饥饿时间（0、2、4、6、9、11 d）处理后再投喂的补偿生长。千年笛鲷幼鱼的体重在短时间（2～6 d）的饥饿后下降不大,9 d以上的饥饿可导致幼鱼的体重明显下降。经过饥饿11 d后,鱼体蛋白质含量明显下降,脂肪含量略有下降,灰分含量有所上升,水分含量明显上升,表明千年笛鲷幼鱼在饥饿过程中主要依靠消耗蛋白质作为能量来源。恢复投喂后,各组的鱼体生化组成均恢复到对照组水平。饥饿11 d组鱼在恢复投喂后全部死亡,半致死时间为10～11 d。结果表明：饥饿2 d组的千年笛鲷幼鱼在恢复生长过程中具有超补偿生长能力,该补偿现象通过提高食物转化率达到;饥饿4 d组幼鱼具有完全补偿生长能力;饥饿6 d组幼鱼仅有部分补偿生长能力;饥饿9 d组幼鱼不具有补偿生长能力;饥饿11 d组幼鱼为饥饿致死。图5表1参13     

红鳍笛鲷幼鱼的摄食排空率及不同食物投喂下的生态生长效率

在实验室养殖条件下,应用Elliott-Persson模型研究了红鳍笛鲷幼鱼(体长37.40(±6.84)mm,体质量2.53(±1.30)g]的排空率与摄食率,以及在3种不同饵料(多齿蛇鲻肉糜、斑节对虾肉糜、海水鱼营养配合饲料)投喂下,其生长率、丰满度的变化.结果表明,海水鱼配合饲料投喂下,红鳍笛鲷幼鱼的胃含物(占体重的百分比)随时间的变动为GCW=-0.472T+4.222 (R2=-0.72),胃排空率为每100 9体质量0.472g/h,日摄食量为每100 9体质量(湿重)22.62 9,对配合饲料的食物转换效率为6.85％.红鳍笛鲷幼鱼的摄食具有一定的周律性,摄食高峰出现在18:00.饲喂18 d后研究发现,投喂斑节对虾肉糜的红鳍笛鲷幼鱼的特定生长率为1.58％/d,而投喂配合饲料组和蛇鲻肉的特定生长率分别为1.55％/d和1.22％/d.红鳍笛鲷幼鱼的丰满度在蛇鲻肉糜和斑节对虾肉糜投喂组均有显著变化,而配合饲料组无显著变化.斑节对虾肉糜投喂组的幼鱼成活率最高(90％),其他2种饲料投喂组受试鱼成活率较接近,分别为72.5％、75％.综合考虑,该生长期的红鳍笛鲷幼鱼适当投喂虾肉,配合饲料日投喂2次,并保证在18:00时饱食为宜,有利于提高其成活率和生长率.     

Cloning,expression of Vibrio alginolyticus outer membrane protein‐OmpU gene and its potential application as vaccine in crimson snapper,Lutjanus erythropterus Bloch

The outer membrane proteins of the marine aquatic animal pathogen, Vibrio alginolyticus, play an important role in the virulence of the bacterium and are potential candidates for vaccine development. In this study, the gene encoding an outer membrane protein‐OmpU was cloned and expressed in Escherichia coli. Polyclonal antibodies were raised in rabbits against the purified recombinant OmpU, and the reaction of the antibody was confirmed by Western blotting using the isolated OmpU and the recombinant OmpU of V. alginolyticus. To analyze the immunogenicity of the recombinant OmpU, crimson snapper, Lutjanus erythropterus Bloch, were immunized by intraperitoneal injection, and antibody response was assessed by the enzyme‐linked immunosorbent assay (ELISA). The results demonstrated that the recombinant OmpU produced an observable antibody response in all sera of the vaccinated fish. The vaccinated fish were challenged by virulent V. alginolyticus and observed to have high resistance to infection. These results indicate that the recombinant OmpU is an effective vaccine candidate against V. alginolyticus in L. erythropterus.     

Study of growth and body composition of red snapper <Emphasis Type="Italic">Lutjanus erythropterus</Emphasis> fed diets containing <Emphasis Type="Italic">Escherichia coli</Emphasis> expressing recombinant tilapia insulin-like growth factor-I

ABSTRACT:   To examine the effects of insulin-like growth factor (IGF)-I on the growth performance of fish, juvenile red snapper Lutjanus erythropterus with an initial body weight of approximately 12 g were fed diets containing different amounts of IGF-I containing Escherichia coli BL21 powder (BL21-tIGF-I). The growth of fish was enhanced by lower doses (0.25, 0.5 and 1%), but deteriorated at higher amounts (2.5 and 5%). The best results were obtained with 0.5% BL21-tIGF-I supplementation, which resulted in 154 and 85% weight gain and feed efficiency, respectively. In addition, muscle proteins appeared to be elevated, but muscle lipids were reduced except for in the 1% BL21-tIGF-I group. In contrast, liver lipids were reduced at 0.25, 0.5 and 1%, but increased at 2.5 and 5% BL21-tIGF-I. Furthermore, to examine the effects of BL21-tIGF-I on later-stage red snapper, we selected fish of approximately 23–24 g weight and fed them a diet either with or without 0.5% BL21-tIGF-I for 12 weeks. Results showed that the growth performance of later-stage fish was better with BL21-tIGF-I than those without supplementation after 6 weeks of feeding. The average body weight of fish that did not receive BL21-tIGF-I during the first 6 weeks, but were fed BL21-tIGF-I in weeks 7–12, was significantly higher than those fed without BL21-tIGF-I for the entire experiment. These results suggest that a continuous supply of BL21-tIGF-I may be beneficial for the growth performance of red snapper.     

红鳍笛鲷(♀)×千年笛鲷(♂)子一代杂种优势的微卫星标记分析

利用12对微卫星引物对红鳍笛鲷(♀)、千年笛鲷(♂)及其红鳍笛鲷(♀)×千年笛鲷(♂)子一代(F1)3个群体进行扩增,对3个群体的等位基因频率、群体多态信息含量、有效等位基因数、杂合度、Shannon信息指数及群体间遗传距离进行了遗传检测,共检测到29个等位基因,平均每个基因座位2.4167个等位基因。红鳍笛鲷、F1、千年笛鲷3个群体的多态信息含量分别为0.3484、0.5008、0.4097;有效等位基因数分别为1.9787、2.5074、2.1334;杂合度分别为0.6548、1.0000、0.7384;Shannon信息指数分别为0.6207、0.9240、0.6957。红鳍笛鲷(♀)-F1、F1-千年笛鲷(♂)、红鳍笛鲷(♀)-千年笛鲷(♂)的遗传距离分别为0.3116、0.2346、0.7813。多态信息含量、有效等位基因数、杂合度、Shannon信息指数均显示F1代有杂种优势。     

红鳍笛鲷(♀)与千年笛鲷(♂)杂交F1代及其亲本的核型研究

采用胸腔活体注射PHA及秋水仙素溶液,取头肾细胞,低渗处理,空气干燥法制片,对染色体进行Giemsa染色,研究红鳍笛鲷(♀)与千年笛鲷(♂)杂交F1代及其亲本的核型。结果表明,杂交F1代及其亲本(红鳍笛鲷和千年笛鲷)的核型相同,均为2 n=48 t,NF=48,符合遗传理论。