First isolation and characterization of a new species of Vibrio from diseased flounder (Paralichthys olivaceus Temminck et Schlegel)

Appropriate pathogenic bacteria were isolated from diseased (or dead) flounder (Paralichthys olivaceus L) occurring in a mariculture farms of Qinhuangdao, which all diseased fishes expressed bacterial septicaemia. The phenotypic information of the 12 pure cultures was studied extensively, including morphological characteristics, colony characteristics in different media, physiological and biochemical characteristics, and the mole fraction G C ratio of the DNA for representative strain. The results show that the isolates belong to a new species of Vibrio, and are designated as Vibrio qinhuangdaora sp.nov, by the area from which the diseased flounders are collected (Qinhuangdao) based on its biological properties following Rules of International Code of Nomenclature of Bacteria. At the same time,studies on the serum homology ofisolates, and pathogenicity of isolates were conducted by experimental infection. The results show that all the isolates are of serologic similarity, and the isolates have strong pathogenicity to flounder. The studies can extensively reflect the main biological properties of this new species of Vibrio.     

Temporal partitioning of microhabitat use among four juvenile fish species of the genus Diplodus (Pisces: Perciformes,Sparidae)

Timing, microhabitat selection and behavior from the onset of settlement to recruitment to the adult population of juvenile fishes of the genus Diplodus (Pisces: Sparidae) were investigated along a rocky coastline in the Central Mediterranean Sea. The settlement periods in Diplodus sargus and Diplodus annularis were concentrated in spring, between late May and early June, and the recruits leave the nursery grounds in late September–October. Juvenile fishes of Diplodus puntazzo and Diplodus vulgaris showed a partial time overlapping, sharing the same zones in winter and early spring, from February to May. Multiple correspondence analysis showed that sea breams settle in well‐defined habitats. The smallest juveniles of D. sargus and D. puntazzo settled primarily in the shallowest sheltered pebbly areas, located in sciaphilous crannies covered by red algae. Diplodus vulgaris settlers were observed on a wider range of substrata: rock on sand, gravel and pebbles without algal cover or large boulders, generally in deeper waters. The intermediate‐size juveniles of D. sargus, D. puntazzo and D. vulgaris showed a preference for rocky substrata with substantial algal cover, with arborescent structures (Phaeophyceae). Diplodus annularis juveniles showed high fidelity to seagrass beds (Posidonia oceanica). The home range increased over time in all species, highlighting a loss of substrate specificity: larger juveniles were even observed in deeper and different microhabitats outside nursery grounds. This study suggests that shallow infra‐littoral rocky communities with photophilic algae play a key role in recruitment of sparid fishes, affecting the distribution and abundance of juvenile fishes and therefore determining the renewal of populations and the structure of adult assemblages.     

In vitro acute cytotoxicity of the neonicotinoid insecticide acetamiprid to FG cells, the gill cell line of flounder Paralichthy olivaceus

1 IntroductionAcetamiprid (( E)-N1-[( 6-chlor-3-pyridyl )methyl]-N2-cyano-N1-methylacetamidine), a cyano-substituted neonicotinoid compound ( Kagabu,1999), is a relatively newclass of insectide, exhibi-ting a broad insecticidal spectrum ( Matsunaka,2000; …     

甲基汞在褐牙鲆幼鱼体内蓄积的组织特异性及其对免疫功能和生长的毒性作用

甲基汞(MeHg)对鱼类多种生命过程存在极强的毒性作用,但有关其对海水鱼类免疫功能的毒性作用研究较少。本文利用实验毒理学方法研究了MeHg(暴露浓度0.0, 0.1, 1.0, 10.0, 20.0μg/L;暴露时间30天)在褐牙鲆(Paralichthys olivaceus)幼鱼组织(鳃、肝脏和脾脏)中的蓄积特征及其对幼鱼的四种免疫功能生物指示物(溶菌酶LZM、酸性磷酸酶ACP、碱性磷酸酶AKP和免疫球蛋白MIgM)和生长的毒性作用。结果表明,幼鱼体内MeHg蓄积量具有显著的浓度依赖性和组织特异性,各组织对MeHg的蓄积能力总体上呈现肝脏鳃脾脏的趋势;四种免疫功能生物指示物(活性或含量)对不同MeHg浓度暴露的响应方式各异,且具有显著的组织特异性; MeHg达到一定暴露浓度后显著抑制幼鱼的生长。总体而言,MeHg在褐牙鲆幼鱼体内蓄积,对其产生免疫毒性,并抑制幼鱼的生长。此外,ACP、AKP和LZM等免疫性指标能较好的反映对MeHg暴露的浓度依赖关系和组织特异性,可作为海水环境中MeHg污染风险评估和生物毒性分析的潜在生物指示物。     

鱼类淋巴囊肿病毒靶器官的组织病理研究

探讨病毒传播途径,运用组织病理学技术,对患淋巴囊肿病毒病的牙鲆和鲈鱼的组织进行显微观察,并对病毒感染的靶器官进行了研究。结果表明,在牙鲆体表皮下结缔组织中,当大量成纤维细胞膨大、变圆,大小为10~18μm时,细胞膜外未出现囊壁,少数细胞的细胞质中观察到嗜碱性物质;18~20μm的膨大细胞在细胞膜外出现囊壁,细胞质内出现嗜碱性物质;>20μm的细胞具有了淋巴囊肿细胞的典型特征。另外,在牙鲆鳃、肠上皮下结缔组织和粘膜下层中,脾、头肾边缘组织和表面系膜、肝表面系膜,以及鲈鱼的鳃等部位均观察到淋巴囊肿细胞,并在牙鲆和鲈鱼脾内观察到膨大细胞。因此,淋巴囊肿病毒的靶器官主要是鱼体表皮下结缔组织,其次是鳃、体腔膜、肠、脾和头肾。鱼体表皮下结缔组织是淋巴囊肿病毒病的检测、检疫和早期诊断的最佳样品。     

用显微注射方法分析牙鲆肌肉发育调节基因MyoD, Myf5的启动子序列

克隆了牙鲆(Paralichthys olivaceus)肌肉发育调节基因MyoD和Myf5的启动子序列,分别为608 bp和1 073 bp。对序列进行分析发现MyoD和Myf5的启动子含有参与肌肉发育调控的基因的结合位点。将MyoD和Myf5的启动子连接到GFP载体上,构建了重组质粒MyoDP-GFP和Myf5P-GFP,并注射到一细胞或两细胞的斑马鱼胚胎中,对这两个基因的启动子进行了瞬时表达研究。结果表明,牙鲆MyoD和Myf5的启动子可以驱动绿色荧光蛋白特异地在斑马鱼肌肉纤维中表达,因此牙鲆608 bpMyoD和1073 bpMyf5的启动子包含着可以驱动MyoD和Myf5正常表达的必需元件,它们是肌肉特异的,并且可以跨物种行使其功能。     

一种新的牙鲆病原菌——兔莫拉氏菌

目前国内外已报道的牙鲆(Paralichthys olivaceus)细菌病的病原有鳗弧菌(Vibrio anguillarum)以及弧菌(Vibrio spp.)属的其他一些种类、爱德华氏菌(Edwardsiella tarda)、屈挠杆菌(Flexibacter maritimus)、肠球菌(Enterococcus seriolicida)、链球菌(Streptococcus spp.)、卡帕奇诺卡氏菌(Nocardia kampachi)、变异微球菌(Micrococcus varians)[1].     

Genetic diversity in two Japanese flounder populations from China seas inferred using microsatellite markers and COI sequences

Japanese flounder is one of the most important commercial species in China; however, information on the genetic background of natural populations in China seas is scarce. The lack of genetic data has hampered fishery management and aquaculture development programs for this species. In the present study, we have analyzed the genetic diversity in natural populations of Japanese flounder sampled from the Yellow Sea (Qingdao population, QD) and East China Sea (Zhoushan population, ZS) using 10 polymorphic microsatellite loci and cytochrome c oxidase subunit I (COI) sequencing data. A total of 68 different alleles were observed over 10 microsatellite loci. The total number of alleles per locus ranged from 2 to 9, and the number of genotypes per locus ranged from 3 to 45. The observed heterozygosity and expected heterozygosity in QD were 0.733 and 0.779, respectively, and in ZS the heterozygosity values were 0.708 and 0.783, respectively. Significant departures from Hardy-Weinberg equilibrium were observed in 7 of the 10 microsatellite loci in each of the two populations. The COI sequencing analysis revealed 25 polymorphic sites and 15 haplotypes in the two populations. The haplotype diversity and nucleotide diversity in the QD population were 0.746±0.072 8 and 0.003 34±0.001 03 respectively, and in ZS population the genetic diversity values were 0.712±0.047 0 and 0.003 18±0.000 49, respectively. The microsatellite data (F_st =0.048 7, P<0.001) and mitochondrial DNA data (F_st =0.128, P<0.001) both revealed significant genetic differentiation between the two populations. The information on the genetic variation and differentiation in Japanese flounder obtained in this study could be used to set up suitable guidelines for the management and conservation of this species, as well as for managing artificial selection programs. In future studies, more geographically diverse stocks should be used to obtain a deeper understanding of the population structure of Japanese flounder in the China seas and adjacent regions.