The complete mitochondrial genome of Chinese rare minnow, Gobiocypris rarus (Teleostei: Cypriniformes)

The Chinese rare minnow, Gobiocypris rarus, which is endemic to China, is an attractive aquatic laboratory animal in China. In the present study, the complete mitogenome sequence of G. rarus has been determined using long polymerase chain reaction (PCR) method. It was 16,601 bp in length and contained 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and a control region, the gene composition and order of which are similar to most other vertebrates. Except for eight tRNA and ND6 genes, all other mitochondrial genes are encoded on the heavy strand. The overall base composition of the heavy strand is 29.5% A, 27.6% T, 25.7% C, and 17.2% G, with a slight AT bias of 57.1%. There are 10 regions of gene overlap totaling 27 bp and 13 intergenic spacer regions totaling 63 bp. The mitogenome sequence of G. rarus could contribute to a better solution of its phylogenetic position within cyprinid fishes based on the whole mitogenomic data.     

Effect of water temperature on reproductive performance and offspring quality of rare minnow,Gobiocypris rarus

Water temperature plays a significant role in the reproductive processes of temperate fishes. In the present study, the effects of water temperature on the reproductive performance and offspring quality of rare minnow (Gobiocypris rarus) were evaluated by cultured parent fish at different temperature (18～30 ℃) in a 2-month trial. The results revealed that rare minnows could spawn continuously within the range from 18 ℃ to 30 ℃, and these at 24 ℃ and 27 ℃ spawned every 3–4 days. Batch size of rare minnow increased with increasing water temperature, while egg production increased with increasing water temperature and then decreased at 30 ℃. High water temperature (30 ℃) had significantly adverse effects on fertilization rate and hatching rate (P<0.05). It was found that the oocyte growth at 18 ℃, 21 ℃, and 30 ℃ were slower than those at 24 ℃ and 27 ℃. Histologic analysis further showed that low temperature (18 ℃ and 21 ℃) slowed down vitellogenesis and oocyte maturation, while high temperature (30 ℃) had suppressive effects on oocyte maturation and ovulation. Based on present results, it was concluded that 24–27 ℃ was optimal breeding temperature for rare minnows and water temperature higher than 30 ℃ resulting from climate change would pose a threat to its wild populations.     

Vitellogenin in rare minnow (Gobiocypris rarus): identification and induction by waterborne diethylstilbestrol

Rare minnow (Gobiocypris rarus) is a tiny Chinese carp that has a short life cycle and is easily cultured in the laboratory. In this study, juvenile rare minnows were exposed to waterborne diethylstilbestrol (DES) at 0.05, 0.5 and 5 microg/l in laboratory aquaria. After exposure for 4, 8, 13 and 21 days, juvenile fish were collected and vitellogenin (Vtg) was measured in whole body homogenates. Native and SDS electrophoresis followed by Western blotting were performed for Vtg identification, and a non-competitive ELISA was developed. In the DES exposure groups (0.5 and 5 microg/l DES), Vtg appeared after 4 days, increased significantly after 8 days and reached a maximum on day 13. Further, a significant increase in the hepatosomatic index (HSI) was found in the 5 microg/l DES exposure group after 21 days. These results indicate that rare minnow provides a good model for assessing endocrine disruption by environmental estrogens.     

Morphological variability between wild populations and inbred stocks of a Chinese minnow, Gobiocypris rarus

Gobiocypris rarus, a small, native cyprinid fish, is currently widely used in research on fish pathology, genetics, toxicology, embryology, and physiology in China. To develop this species as a model laboratory animal, inbred strains have been successfully created. In this study, to explore a method to discriminate inbred strains and evaluate inbreeding effects, morphological variation among three wild populations and three inbred stocks of G. rarus was investigated by the multivariate analysis of eight meristic and 30 morphometric characters. Tiny intraspecific variations in meristic characters were found, but these were not effective for population distinction. Stepwise discriminant analysis and cluster analysis of conventional measures and truss network data showed considerable divergence among populations, especially between wild populations and inbred stocks. The average discriminant accuracy for all populations was 82.1% based on conventional measures and 86.4% based on truss data, whereas the discriminant accuracy for inbred strains was much higher. These results suggested that multivariate analyses of morphometric characters are an effective method for discriminating inbred strains of G. rarus. Morphological differences between wild populations and inbred strains appear to result from both genetic differences and environmental factors. Thirteen characters, extracted from stepwise discriminant analysis, played important roles in morphological differentiation. These characters were mainly measures related to body depth and head size.     

Isolation and characterization of Argonaute 2: a key gene of the RNA interference pathway in the rare minnow, Gobiocypris rarus

Argonaute 2 gene plays a pivotal role in RNAi in many species. Herein is the first report of the cloning and characterization of Argonaute 2 gene in fish. The full-length cDNA of Gobiocypris rarus Argonaute 2 (GrAgo2) consisted of 3073 nucleotides encoding 869 amino acid residues with a calculated molecular weight of 98.499 kDa and an estimated isoelectric point of 9.18. Analysis of the deduced amino acid sequence showed the presence of two signature domains, PAZ and Piwi. RT-PCR analysis indicated that GrAgo2 mRNA expression could be detected in widespread tissues. After infection with grass carp reovirus, GrAgo2 expression was up-regulated from 12 h post-injection (p < 0.05) and returned to control levels at 48 h post-injection (p > 0.05). These data imply that GrAgo2 is involved in antiviral defense in rare minnow.     

Germ cell development in the Honeybee (Apis mellifera); Vasa and Nanos expression

Background  

Studies of specification of germ-cells in insect embryos has indicated that in many taxa the germ cells form early in development, and their formation is associated with pole plasm, germ plasm or an organelle called the oosome. None of these morphological features associated with germ cell formation have been identified in the Honeybee Apis mellifera. In this study I report the cloning and expression analysis of Honeybee homologues of vasa and nanos, germ cell markers in insects and other animals.     

稀有鮈鲫血液学指标的研究

稀有鲫( Gobiocypris rarus Ye et Fu) 是中国特有的一种小型鲤科鱼类, 具有生命力强、性成熟周期短、繁殖季节长、产卵频率高等特点。目前已被广泛应用于遗传学、发育生物学、胚胎学、分子生物学、毒理学、污染生物学等研究领域。       

稀有鮈鲫(Gobiocypris rarus)的骨骼特征及系统发育地位

稀有鮈鲫(Gobiocypris rarus)已作为新型实验动物而逐渐成为生物学研究各领域的热门对象,但是,其系统分类位置仍存在争议。本研究制作了稀有鮈鲫的透明骨骼标本,对其骨骼特征进行描述;选取47个形态特征,与鲤科各亚科鱼类的典型特征进行比较,建立了分支分析特征矩阵,并使用PAUP4.0软件中的最大简约法(MP)构建系统发育树。结果显示,稀有鮈鲫和鮈亚科鱼类聚在一起,属于鮈亚科。     

Shrinkage of Gobiocypris rarus, Procypris rabaudi, and Sinilabeo rendahli preserved in formalin

Length measurements of preserved fishes are necessary in many types of fish surveys because logistics often do not allow for fish measurement immediately after catch. If the fixative causes significant shrinkage, then the preserved lengths cannot be directly used to indicate accurate live lengths. The objective of this study was to determine how preservation in formalin affects standard length of Gobiocypris rarus larvae (24‐day‐old and newly hatched), larval Procypris rabaudi (4‐day‐old), and larval Sinilabeo rendahli (12‐day‐old). Fishes were measured (to nearest 0.01 mm) and individually fixed in the appropriate formalin solution (2.5% or 5.0% formalin), then re‐measured at 0.5, 1, 3, 7, 14, 30, 45 and 75 days after preservation to follow the time course of shrinkage. Most of the shrinkage occurred within the first half day after preservation. The 5.0% formalin caused a higher relative shrinkage rate than did the 2.5% solution; however, the difference was not statistically significant. In G. rarus, initial shrinkage of newly hatched larvae was higher than that of 24‐day‐old larvae.     

人工养殖稀有鮈鲫消化道组织学观察

采用活体解剖和显微技术对人工养殖的稀有鮈鲫消化道组织结构进行了详细观察,并描述了其形态结构。结果表明:稀有鮈鲫为杂食性无胃鱼,肠道系数0.64±0.06。消化道包括口咽腔、食道、肠和肛门。口咽腔和食道粘膜层为复层扁平上皮,内含较多杯状细胞、粘液细胞和少量味蕾;食道粗短,肌肉层发达。肠由前肠、中肠和后肠三部分组成。肠道由前到后,粘液细胞数量逐渐增多,粘膜皱褶数量逐渐减少,粘膜皱褶高度逐渐降低。     

Germ cell specific promoter drives ectopic transgene expression during embryogenesis

In this study, we used the male germ cell-specific phosphoglycerate kinase 2 (Pgk2) promoter to generate Pgk2Cre transgenic mice to allow investigation of genes critically involved in meiosis. The Pgk2 promoter had been used previously to target transgene expression to spermatocytes and spermatids in several laboratories including ours. In several Cre targeting experiments using other promoters, ectopic Cre expression had been observed, but the timing and extent of this expression was not analyzed. We demonstrate that in adult mice the Pgk2Cre transgene is expressed specifically in spermatocytes and spermatids, as expected. However, in offspring from matings of Pgk2Cre mice and an H19loxP indicator strain, we discovered that recombination events had occurred in several, but not all, tissues to varying extents. The lacZ-loxP transgenic indicator strain was next used to uncover ectopic Cre expression even in single cells, which indicated that the Pgk2Cre transgene is expressed between days 11 and 15 during embryogenesis in several tissues and organs. Using an RT PCR assay we were unable to detect endogenous Pgk2 mRNA during embryogenesis or in adult tissues other than testis. In conclusion, the Pgk2 promoter is a valid choice for targeting gene expression to meiotic male germ cells, since transient ectopic expression is unlikely to have a discernable effect in most studies, but it may be inappropriate for utilization with Cre recombinase.     

野生和近交稀有Ju鲫的遗传多样性

用ＲＡＰＤ技术对稀有Ｊｕ鲫近交１０代及３个野生群体的遗传多样性和群体间差异进行了研究。无论从多态位点的比例,个体间的共带率还是多样性指数来看,近交１０代的遗传多样性极低。在２２６个ＲＡＰＤ位点中,野生群体有近半数的位点是多态的,Ｓｈａｎｎｏｎ多样性指数在０．２９１１－０．３２３５间,表明自群本保持了较丰富遗传多样性。近交１０代与野生群体间遗传差异十分明显。野生群体间在１１－１９个位点上的表型频率存     

Development of EST-SSRs by an efficient FIASCO-based strategy: a case study in rare minnow (Gobiocyrpis rarus)

Type I markers are useful for comparative mapping and other genetic analyses, but relatively difficult to develop. In the present study a microsatellite (SSR)-enriched cDNA library was constructed for the first time using the fast isolation by AFLP of sequences containing repeats (FIASCO) method in a small fish, Chinese rare minnow (Gobiocypris rarus). A total of 97.4% of the expressed sequence tags (ESTs) contained targeted CA-repeats, in which 29 unique EST-SSRs were identified. Ten out of the 28 loci for which primer pairs were designed were polymorphic with alleles ranging from three to seven (mean 4.50). Some of these EST-SSRs can be amplified in other species. These results proved that cDNA-FIASCO is an efficient way to isolate novel EST-SSRs in a fish.