大黄鱼库道虫病的初步研究

在广东湛江海水网箱养殖的大黄鱼 (Pseudosciaenacrocea)中发现了库道虫病 (Kudoasis) ,检出率高达 31%。其症状表现为 :白色孢囊分布于胸鳍、腹鳍、臀鳍和尾鳍等的鳍膜下 ,剖检时发现腹壁和背部肌肉中布满许多白色呈球形或椭圆形的小孢囊 ,在肠系膜、腹膜以及近口腔的粘膜上也有大量的白色小孢囊分布。镜检发现孢囊中含有典型的库道虫 ,其孢子宽为 ( 8 90± 0 55) μm ,长为 ( 8 35± 0 4 6 ) μm ,极囊宽为 ( 2 39± 0 36 ) μm ,极囊长为 ( 4 4 8± 0 39) μm。孢子在淡水中 2 0min后全部死亡 ,在盐度为 6的水体中 ,12h和 2 4h后存活率分别约为 87.4 %和 70 % ;在盐度为 16、2 6和 36的水体中 ,孢子存活率均为 10 0 % ;在盐度为 4 6的水体中 ,12h和 2 4h后存活率分别约为92 %和 84 %。孢子对低温有较强的耐受力 ,当水温达到 4 4℃时 ,8h、12h和 2 4h后 ,孢子的存活率分别约为 91%、80 .5%和 6 6 %。     

Dietary Leucine Requirement for Juvenile Large Yellow Croaker Pseudosciaena crocea (Richardson,1846)

Dietary leucine requirement for juvenile large yellow croaker, Pseudosciaena crocea Richardson 1846 (initial body weight 6.0 g±0.1 g) was determined using dose-response method.Six isonitogenous (crude protein 43%) and isoenergetic (19 kJ g-1) practical diets containing six levels of leucine (Diets 1-6) ranging from 1.23% to 4.80% (dry matter) were made at about 0.7% increment of leucine.Equal amino acid nitrogen was maintained by replacing leucine with glutamic acid.Triplicate groups of 60 individuals were fed to apparent satiation by hand twice daily (05:00 and 17:30).The water temperature was 26-32℃, salinity 26-30 and dissolved oxygen approximately 7 mg L-1 during the experimental period.Final weight (FW) of large yellow croaker initially increased with increasing level of dietary leucine but then decreased at further higher level of leucine.The highest FW was obtained in fish fed diet with 3.30% Leucine (Diet 4).FW of fish fed the diet with 4.80% Leucine (Diet 6) was significantly lower than those fed Diet 4.However, no significant differences were observed between the other dietary treatments.Feed efficiency (FE) and whole body composition were independent of dietary leucine contents (P0.05).The results indicated that leucine was essential for growth of juvenile large yellow croaker.On the basis of FW, the optimum dietary leucine requirement for juvenile large yellow croaker was estimated to be 2.92% of dry matter (6.79% of dietary protein).     

A Fast and Indirect Fluorescent Antibody Assay for the Vibrio in Large Yellow Croaker Pseudosciaena crocea (Richardson)

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A Comparison Study on Flesh Quality of Large Yellow Croaker(Larimichthys croceus) Cultured with Three Different Modes

To compare the flesh quality of large yellow croaker cultured with three different modes, enclosure culture(EC), cage culture with feeding trash fish(CCF) and cage culture with feeding formula diet(CCD), thirty six fish individuals of EC(484.6 ± 79.8 g), CCF(432.7 ± 87.9 g) and CCD(416.9 ± 49.5 g) were sampled to measure body color, flesh water holding capacity, flesh proximate composition, amino acids and fatty acids composition, and collagen and inosinic acid contents. The analysis showed that there was no significant difference in the yellowness of skin and the contents of crude protein and inosinic acid between CCD and EC(P 0.05), and the two modes showed higher values than CCF(P 0.05). Most of the amino acids(AA) in flesh were higher in EC than in CCF(P 0.05), but CCD showed no difference in AA composition from the other two modes(P 0.05). EC and CCD had higher contents of collagen, free AA and lower drip loss than CC(P 0.05). In polyunsaturated fatty acids, EC showed significantly higher levels of C20:5 n-3 and C22:6 n-3 than CCF and CCD(P 0.05), but CCD had significantly higher C18:2 n-6 than CCF and EC(P 0.05). In conclusion, the flesh quality of CCD fish is similar to EC fish, and these two modes have better flesh quality than CCF.     

Molecular Characterization,Tissue Distribution and Localization of Larimichthys crocea Kif3a and Kif3b and Expression Analysis of Their Genes During Spermiogenesis

KIF3A and KIF3B are two N-terminal motor proteins belonging to the kinesin-II superfamily that play essential roles in spermiogenesis. To understand the roles played by KIF3 A/3B during spermatogenesis of large yellow croaker Larimichthys crocea, we studied the testis characteristics at different developmental stages of L. crocea, and determined the spatiotemporal expression patterns of kif3a and kif3b during spermiogenesis. Quantitative real-time PCR(qR T-PCR) showed that the overall trends of kif3 a/3 b m RNA abundance during testis development are similar. From stage II to stage V, kif3a/3b m RNA abundances first increased and then fell after reaching a peak at stage IV. Interestingly, the m RNA abundances of both genes at stage V were higher than those at stages II and III. In addition, it is worth of noting that kif3 b m RNA abundance was higher than that of kif3a at all stages. Fluorescence in situ hybridization results revealed that kif3a/3b m RNA abundance dynamics were consistent with the migration of mitochondria, the deformation of nucleus, and the formation of tail. The m RNA hybridization signals of both genes first appeared either around the nuclear periphery or on the side of the nuclei, then appeared at one side of nuclei, and finally were mainly on the tail during spermiogenesis. Our findings contributed to better understanding the molecular mechanisms of spermiogenesis in fish; and suggested that KIF3A and KIF3B may participate in the intracellular transport of mitochondria, nuclear deformation, and the formation of tail during the spermiogenesis in L. crocea.     

Lipid Oxidation and Fatty Acid Composition in Salt-Dried Yellow Croaker(Pseudosciaena polyactis) During Processing

Lipid oxidation in salt-dried yellow croaker(Pseudosciaena polyactis) was evaluated during processing with commonly used analytical indices, such as the peroxide value(POV), the thiobarbituric acid reactive substances(TBARS) value, and oxidative-relative lipoxygenase(LOX) activity. Additionally, fatty acids were analyzed using gas chromatography-mass spectrometry. Both POV and TBARS increased significantly(P 0.05) at the rinsing stage. POV reached its peak value of 3.63 meq O_2 per kg sample at the drying stage, whereas TBARS constantly increased from 0.05 to 0.20 mg MDA per kg sample. Processing of salt-dried yellow croaker had an extremely significant(P 0.01) effect on LOX activity. Twenty-six fatty acids were identified. Combined eicosapentaenoic acid(EPA; C20:5n3) and docosahexaenoic acid(DHA; C22:6n3) content varied between(19.20 ±0.37) mg g~(-1) and(23.45 ± 1.05) mg g~(-1). The polyunsaturated fatty acid/saturated fatty acid(PUFA/SFA) ratio in yellow croaker was 0.73–1.10, and the n-6/n-3 PUFA ratio was approximately 0.13–0.20. The contents of most fatty acids varied significantly(P 0.05) during the different processing stages, and these differences were caused by lipid oxidation. C18:0, C16:1n7, C19:0, and C22:6n3 showed clear changes in principle component one of a principle components analysis. These fatty acids are potential markers for evaluating lipid oxidation in fish muscle because there was a significant correlation between these markers and TBARS and LOX activity(P 0.05) with Pearson's coefficients 0.931.     

Estimated reproductive success of brooders and heritability of growth traits for large yellow croaker (Larimichthys crocea) using microsatellites

We estimated the reproductive success of adult brood fish and the heritability of growth-related traits for large yellow croaker (Larimichthys crocea). We created two independent full-factorial cross groups (1 and 2) by crossing 4 males×4 females and 4 males×3 females, respectively. We measured the body weight (BW), body length (BL), and body height (BH) of 281 individuals from group 1 and 318 individuals from group 2 at 20 months post hatch (harvest age). We also collected a tissue sample from each individual. The parents and offspring were genotyped using six polymorphic microsatellites. Of the 599 offspring, 99.2% were assigned to a single pair of parents. In both groups, some parent pairs produced a large number of offsprings while other pairs did not produce any offspring. The genetic diversity and putative Ne were lower in the offsprings than in the parents in both groups. The heritability estimates at 20-month age were 0.13±0.10 for BW, 0.19±0.13 for BL, and 0.09±0.06 for BH. The genetic and phenotype correlation between BW, BL, and BH was close to 1. The results provide basic information for selective breeding and further genetic characterization of large yellow croaker.     

The Characteristics of vasa Gene from Japanese Sea Bass (Lateolabrax japonicas) and Its Response to the External Hormones

The RNA helicase Vasa is an important regulator of primordial germ cell development. Its function in mature fish, especially the hormone-related differences in maturing male fish has seldom been documented. In this study, a full length c DNA sequence of the vasa gene was cloned from Japanese sea bass, Lateolabrax japonicas, and it was named jsb-vasa. Homology analysis showed that jsb-vasa was closely related to its teleost homologs. The spatial distribution of jsb-vasa indicated that it was only highly expressed in testis, showing its germ cell-specific expression pattern. During the testicular development cycle, jsb-vasa was highly expressed during early period of spermatogenesis, and reduced when spermatogenesis advanced. In addition, the jsb-vasa gene expression was significantly inhibited at 6 h, 12 h and 24 h after injecting h CG(human chorionic gonadotropin) and Gn RHa(Gonadotropin-releasing hormone analogue), indicating that jsb-vasa gene may play an important role in spermatogenesis of Japanese sea bass, and be under the regulation of external sex hormones.     

Characterization of Caspase Gene Family Members in Spotted Sea Bass(Lateolabrax maculatus) and Their Expression Profiles in Response to Vibrio harveyi Infection

The caspase gene family is a crucial gene cluster that regulates apoptosis which contribute to programmed cell death, cell proliferation and differentiation, and several immune responses. In our study, a complete set of 12 caspase genes were identified in spotted sea bass Lateolabrax maculatus. These genes were divided into three subfamilies: 2 inflammatory caspases(casp-1 and casp-14-like), 5 apoptosis initiators(casp-2, casp-8a, casp-8b, casp-9, and casp-10), and 5 apoptosis executioners(casp-...     

黄河三角洲人类干扰活动强度变化及其景观格局响应

本研究以湿地变化较为剧烈的黄河三角洲为研究对象,基于RS技术和GIS空间分析方法,利用人为干扰度模型,结合区域人工沟渠建设情况,从区域和局地两个尺度直观揭示人类干扰强度时空分异特征,并探究区域景观格局对人类干扰活动的响应,以期为黄河三角洲滨海湿地生态保护与人类活动调控提供决策支持。结果表明：① 1995-2015年现代黄河三角洲区域人为干扰度和人工沟渠密度均明显增加,空间分布呈现从西南部向东部、北部,自内陆向沿海的扩展趋势;② 随着人类活动强度增强,研究区自然湿地面积减少,区域景观多样性和空间异质性增加,景观整体连通性减弱,景观复杂性降低;③ 景观格局对人类干扰强度变化的响应关系呈现出地区和时间差异;人类干扰活动强度相对较低的保护区受人工沟渠建设的影响,也呈现出斑块团聚程度降低、景观多样性增加和景观复杂性降低的变化趋势;④ 人为干扰度指数和人工沟渠密度指标互为补充,互相印证,可以较为全面、客观地反映黄河三角洲地区人类干扰活动强度。     

马氏珠母贝Su(H)基因克隆与组织特异性表达

Su(H)基因(Suppressor of Hairless gene)对生物体细胞的分化、增殖和凋亡起重要的调控作用。根据马氏珠母贝(Pinctada martensii)转录组数据库中注释为Su(H)的unigene序列设计基因特异性引物,应用cDNA末端快速扩增(RACE)技术克隆获得了马氏珠母贝Su(H)[pm-Su(H)]基因cDNA全长序列。结果表明:pm-Su(H)基因全长3 830 bp,其中开放阅读框含有1 920 bp,编码640个氨基酸残基,5'UTR为1 568bp,3'UTR为342 bp,含有27 bp polyA;预测其分子质量为70.6 ku,等电点为7.38;多序列比对显示,pm-Su(H)与其他物种的Su(H)有较高的保守性,与牡蛎(Crassostrea gigas)的同源序列高达80%;荧光定量PCR分析表明,pm-Su(H)在马氏珠母贝闭壳肌、鳃、珍珠囊、外套膜、肝胰脏、性腺、足、血淋巴等8组织中均有表达,其中以性腺中表达量最高,其次是珍珠囊和外套膜。     

巴马香猪Hsp70基因的克隆、生物信息学分析及其在猪肠上皮细胞IPEC-J2中的表达

为研究热应激蛋白70(HSP70)在巴马香猪(Sus scrofa domestica)耐热中的作用,利用NCBI公布的猪Hsp70基因序列设计引物,用RT-PCR克隆巴马香猪Hsp70基因。核酸序列分析表明,巴马香猪Hsp70基因开放阅读框(ORF)长1 932 bp,编码643个氨基酸。该蛋白分子质量为71.1 ku,等电点(PI)为5.88,与野猪、人、牛、羊、犬和鸡的同源性分别为99.2%、82.8%、83.2%、83.6%、82.4%和77.7%。该蛋白非叶绿体转运肽和线粒体导肽,亦非信号肽分泌通道,存在多个明显的疏水区,其中397位疏水性最强,达2.211。将该基因的ORF与真核表达载体pc DNA 3.1/V5-HisTOPO连接构建真核表达载体,并转染IPEC-J2细胞,荧光定量PCR及Western blot检测可见其在基因和蛋白水平的高量表达。     

Effects of Hypoxia on Dopamine Concentration and the Immune Response of White Shrimp （Litopenaeus vannamei）

Effects of hypoxia on the dopamine concentration and the immune response of White Shrimp Litopenaeus vannamei were studied. The results showed that hypoxia had significant effects on the concentration of dopamine (DA) in the haemolymph, haemocyte count, phenoloxidase activity, phagocytic activity of haemocytes and bacteriolytic and antibacterial activity in the haemolvmph (P<0.05). The concentration of the dopamine in haemolymph reached its maximum in the 3.0 and 1.5mgL-1 DO groups at 12h and 6h, and then returned to normal after 24h and 12h, respectively. All immune parameters decreased with the reduction of dissolved oxygen. Total haemocyte count (THC), the hyaline cells and semi-granular cells in the 3.0mgL-1 DO group became stable after 12h,while granular cells did so after 24h, The THC and different haemocyte count (DHC) in the 1.5mgL-1 DO group became stable alter 24h. Phenoloxidase activity and bacteriolytic activity in the 3.0 and 1.5mgL-1 DO groups reached their stable levels after 24 h and 12 h respectively, while phagocytic activity and antibacterial activity became stable after 24 and 12, and 36 and 24 It, respec-tively. It was also indicated that the changes of dopamine concentrations in haemolymph, haemocyte count and phenoloxidase activ-ity were obviously related to the exposure time under hypoxic conditions.