Parentage determination of mandarin fish (Siniperca chuatsi) based on microsatellite DNA markers

In this study, ten microsatellite loci were chosen to estimate the parentage of 260 progeny in five mandarin fish (Siniperca chuatsi) full-sib families. Simulation based on allele frequency date demonstrated the combined exclusion power would be over 97% if the number of loci was up to nine. Based on the information from these nine loci, 98% of progeny were unambiguously allocated to their putative parental pairs in the parentage analysis. The assignment success rate by the real data set was lower than that predicted by the simulations, with 94% of progeny assigned correctly. The discrepancies might be caused by a scoring error or allelic dropout caused by poor quality genomic DNA. Moreover, 69 progeny were selected randomly for the double-blind test, the result indicated that 95% of the progeny can be correctly assigned to their families. This study provided a microsatellite-based approach for parentage assignment in S. chuatsi, and that will be useful for investigation of genetic background and molecular marker-assisted selective breeding in this species.     

水体对网箱养鳜的承载力

通过分析浮桥河水库氮、磷含量 ,确定磷为水体营养物的限制性因子 ;根据水库的中 -富营养化现状 ,确定磷浓度 0 .0 6 6mg/ L——水库中游的磷浓度为水体允许的最高磷浓度 ;结合我国现有的实际情况 ,在 Dillon- Rigler模型的基础上建立了包含水体的有效库容系数、营养水平、养殖强度和养殖对象等参数的动态模型 ,并由此模型计算出浮桥河水库的网箱养殖容量 :单一养殖鳜鱼时为 1.6 0‰ ,单一养殖建鲤时为 0 .2 1‰ ;配套养殖时 ,鳜鱼为 0 .31‰ ,建鲤为 0 .2 1‰ ,总容量为 0 .5 2‰ ;对水体网箱容量的磷限制性标准的制定进行了讨论 ,在模型理论的基础上提出了水体环境调控措施 ,并建议养殖水体以食鱼性网箱养殖为主 ,饵料鱼网箱为辅。     

Effects of turbidity and light intensity on foraging success of juvenile mandarin fish Siniperca chuatsi (Basilewsky)

This study aimed to evaluate the effects of turbidity and light intensity on foraging success of juvenile mandarin fish Siniperca chuatsi. Predation on crucian carp Carassius auratus by juvenile mandarin fish was tested at five levels of turbidity combined with two light intensities, imitating daylight and night in two turbidity types. Foraging success was significantly lower in clay-induced turbidity than in algal-induced turbidity. In clay-induced turbidity trials, there was a slight but insignificant increase in foraging success of mandarin fish with increasing turbidity under lighted conditions. In algal-induced turbidity trials, there were no significant differences in foraging success of mandarin fish among turbidity levels at both light and dark levels, but at 80 NTU turbidity level, foraging success was lower than in all the other turbidity levels. There was no significant difference in foraging success at different turbidities under darkness. These results suggest that piscivory of mandarin fish is influenced by different turbidity types but is not significantly influenced by increased turbidity combined with decreased light intensity.     

Characterization and expression of Cd8 molecules in mandarin fish Siniperca chuatsi

The full‐length complementary DNA (cDNA) sequences encoding cd8α and cd8β molecules were sequenced and characterized from mandarin fish Siniperca chuatsi. Conserved motifs and residues were found to be present in derived peptides of the Cd8 molecules. For example, WXR motif, DXGXYXC motif, and four cysteine residues were present in the extracellular region of the Cd8 protein. Threonine, serine and proline residues involved in multiple O‐linked glycosylation events were located in the membrane proximal hinge region. The common CPH motif in the cytoplasmic tail was detected similar to other teleost Cd8 molecules. Different from those in mammals, S. chuatsi Cd8 sequences have many extra cysteine residues (C149 in Cd8α sequence and C46, C51 and C158 in Cd8β sequence), which also exist in other teleost Cd8 molecules. Real‐time polymerase chain reaction (RT‐PCR) and Western blot analyses revealed that the thymus had the highest expression of cd8 messenger (m)RNA and protein. After stimulated with phytohaemagglutinin, polyriboinsine‐polyribocyaidylic acid and concanavalin A (ConA), the expression level of cd8 mRNA increased significantly in head‐kidney lymphocytes at 4 and 8 h, but decreased to normal level at 12 h. Similarly, stimulation with ConA in vivo also led to an increase in the cd8 mRNA level in the spleen. Immunohistochemistry analysis demonstrated that Cd8α‐positive cells can be detected in the thymus, spleen and intestine by using polyclonal anti‐Cd8α antibody.     

Isolation and characterization of 18 polymorphic microsatellite markers in Chinese mandarin fish Siniperca chuatsi (Basilewsky)

Eighteen microsatellite markers were isolated and characterized using an enrichment protocol in the Chinese mandarin fish Siniperca chuatsi (Basilewsky), a commercially important piscivorous fish in China. Out of 48 pairs of primers designed, 18 loci exhibited polymorphism with three to six alleles (mean 4.4 alleles/locus) and average observed heterozygosity ranged from 0.633 to 0.833 (mean 0.748) in a test population from Dongting Lake of China. Except for two loci, all other 16 loci were in the Hardy–Weinberg equilibrium. These markers would be useful for such studies as population genetics, ecology and selective breeding of the Chinese mandarin fish in future.     

Resting metabolism and heat increment of feeding in mandarin fish (Siniperca chuatsi) and Chinese snakehead (Channa argus)

Resting metabolism was measured in immature mandarin fish Siniperca chuatsi weighing 42.1-510.2 g and Chinese snakehead Channa argus weighing 41.5-510.3 g at 10, 15, 20, 25, 30 and 35 degrees C. Heat increment of feeding was measured in mandarin fish weighing 202.0 (+/-14.0) g and snakehead weighing 200.8 (+/-19.3) g fed swamp loach Misgurnus anguillicaudatus at 1% body weight per day at 28 degrees C. In both species, weight exponent in the power relationship between resting metabolism and body weight was not affected by temperature. The relationship between resting metabolism and temperature could be described by a power function. The temperature exponent was 1.39 in mandarin fish and 2.10 in snakehead (P<0.05), indicating that resting metabolism in snakehead increased with temperature at a faster rate than in mandarin fish. Multiple regression models were used to describe the effects of body weight (W, g) and temperature (T, degrees C) on the resting metabolism (R(s), mg O(2)/h): lnR(s)=-5.343+0.772 lnW+1.387 lnT for the mandarin fish and lnR(s)=-7.863+0.801 lnW+2.104 lnT for the Chinese snakehead. The proportion of food energy channelled to heat increment was 8.7% in mandarin fish and 6.8% in snakehead.     

Ontogenetic development and otolith microstructure in the larval and juvenile stages of mandarin fish Siniperca chuatsi

Ichthyological Research - The mandarin fish Siniperca chuatsi (Perciformes: Percichthyidae) is a commercially important freshwater fish in China. However, S. chuatsi populations have declined...     

鳜鱼头肾的组织发生及成鱼头肾B淋巴细胞的分布

通过整体连续切片,研究了鳜鱼不同发育时期的头肾结构,并利用原位PCR方法检测了B淋巴细胞在鳜鱼头肾中的分布。在孵化后第1d观察到了肾组织,主要由肾小管组成。尔后头肾的发育经历了三个结构和功能的转变。第一个阶段为孵化后第1d到第7d,头肾作为滤过性器官存在,由肾小管及少量淋巴细胞组成。第二个阶段从第8d到第36d,是一个功能混合型阶段,头肾中既有肾小管,又有造血组织;随时间推移,肾小管数量减少,淋巴细胞数量剧增。紧接着进入第三个阶段：肾小管完全消失,头肾中开始出现大量的嗜铬细胞,头肾作为淋巴-肾上腺组织而存在。肾上腺首先出现在头肾前端,随发育成熟,集中分布于头肾门静脉周围。IgM在鳜头肾中大量表达,IgM分泌细胞分布于整个头肾组织,在血管周围有集中趋势[动物学报51(3)：440—446,20051。     

Characterization and ontogenetic expression analysis of the myosin light chains from the fast white muscle of mandarin fish Siniperca chuatsi

Three full-length complementary DNA (cDNA) clones were isolated encoding the skeletal myosin light chain 1 (MLC1; 1237 bp), myosin light chain 2 (MLC2; 1206 bp) and myosin light chain 3 (MLC3; 1079 bp) from the fast white muscle cDNA library of mandarin fish Siniperca chuatsi. The sequence analysis indicated that MLC1 and MLC3 were not produced from differentially spliced messenger RNAs (mRNA) as reported in birds and rodents but were encoded by different genes. The MLC2 encodes 170 amino acids, which include four EF-hand (helix-loop-helix) structures. The primary structures of the Ca(2+)-binding domain were well conserved among the MLC2s of seven other fish species. The ontogenetic expression analysis by real-time PCR showed that the three light-chain mRNAs were first detected in the gastrula stage, and their expression increased from the tail bud stage to the larval stage. All three MLC mRNAs showed longitudinal expression variation in the fast white muscle of S. chuatsi, especially MLC1 which was highly expressed at the posterior area. Taken together, the study provides a better understanding about the MLC gene structure and their expression pattern in muscle development of S. chuatsi.     

基于异源cDNA基因芯片杂交的鳜鱼肌肉组织基因表达谱初步分析

cDNA基因芯片技术已广泛应用于生物物种间功能基因组和表达谱学研究。然而,鱼类基因芯片开发和应用相对落后。为了筛选与肉质性状相关功能基因,本研究首次试用异源斑马鱼基因cDNA芯片,对两种肉质性状明显差异的鳜鱼和鲢鱼肌肉组织中基因表达进行了比较分析。从两种鱼肌肉组织中提取总RNA,经Biotin荧光标记与拥有15617个cDNA片段的斑马鱼基因芯片（Affymetrix）杂交后,检测出375个表达基因。与鲢鱼比较,鳜鱼肌肉组织锁定的基因中有180个上调表达基因和195个下调表达基因。在鳜鱼肌肉组织180个上调基因中,49个为已知功能基因,131个为未知功能基因。根据基因文库同源功能基因分析,我们将49个已知上调基因按功能大约分为七大类,其中与肌肉结构相关基因包括肌球蛋白重链基因（MYH）、肌纤维间连接基因和细胞骨架结构基因等。同时,我们对与肉质结构性状密切相关的功能基因进行了分析,并结合与鳜鱼优良肉质结构和功能基因表达关系进行了讨论。     

Feeding habits and predator‐prey size relationships of mandarin fish Siniperca chuatsi (Basilewsky) in a shallow lake,central China

The diet and predator‐prey size relationships of mandarin fish Siniperca chuatsi (Basilewsky) in Lake Xiaosihai along the middle reach of the Yangtze River were studied through stomach content analysis. A total of 401 specimens (91–539 mm total length) were collected in 2007. The diet was dominated by topmouth gudgeon Pseudorasbora parva, sharpbelly Hemiculter leucisculus, redfin culter Cultrichthys erythropterus, and crucian carp Carassius auratus, with significant seasonal and ontogenetic differences. Ontogenetic variation in diet was apparent that larger prey items such as crucian carp and redfin culter became more common, while smaller prey such as topmouth gudgeon, bitterlings and shrimps gradually declined in the larger fish. Mandarin fish total length (TL) was strongly related to mouth gape width (GW) and gape height (GH). Mandarin fish TL and prey fish TL as well as mandarin fish GW and prey fish body depth (BD) were positively and linearly related for sharpbelly, redfin culter and crucian carp. Strong size selectivity for topmouth gudgeon, sharpbelly and redfin culter as prey indicated that the piscivorous mandarin fish can have potential impact on the population size structure of the three prey fish.     

Relationships of the temperate Australasian labrid fish tribe Odacini (Perciformes; Teleostei)

The labrid tribe Odacini comprises four genera and 12 species of fishes that inhabit shallow kelp forest and seagrass areas in temperate waters of Australia and New Zealand. Odacines are morphologically disparate, but share synapomorphies in fin structure and fusion of teeth into a beak-like oral jaw. A phylogenetic analysis of odacines was conducted to investigate their relationships to other labrid fishes, the relationships of species within the tribe, and the evolution of herbivory within the group. Fragments from two mitochondrial genes, 12S rDNA and 16S rDNA, and two nuclear genes, Tmo4C4 and RAG2, were sequenced for seven odacine species (representing all four genera), eight species representing the other major labrid lineages, and three outgroup species. Maximum likelihood and maximum parsimony analyses on the resulting 2338 bp of DNA sequence produced nearly identical topologies differing only in the placement of a clade containing the cheiline Cheilinus fasciatus and the scarine Cryptotomus roseus. The remaining clades received strong bootstrap support under maximum parsimony, and all clades in the maximum likelihood analysis received high bootstrap proportions and high posterior probabilities. The hypsigenyine labrid Choerodon anchorago formed the sister group to the odacines. Within the odacines, Odax cyanoallix+Odax pullus formed the sister to the remaining odacines, with Odax acroptilus, Odax cyanomelas, and Siphonognathus argyrophanes forming successively closer sister groups to the clade Haletta semifasciatus+Neoodax balteatus. Either herbivory evolved twice in the odacines, or herbivory evolved once with two reversions to carnivory. The latter hypothesis appears more likely in the light of odacine feeding biology.     

Histological observations on lymphomyeloid organs of the Antarctic fish Trematomus bernacchii (Teleostei: Nototheniidae)

Lymphomyeloid organs of the Antarctic fish Trematomus bernacchii were studied with the aim of analysing some morphological aspects related to adaptation to low environmental temperature. The thymus of T. bernacchii was flattened, incompletely lobated and scarcely regionalised. It was filled by lymphoid elements intermingled with stromal elements. The head kidney appeared highly vascularised and mainly lymphopoietic. The spleen appeared mainly erythropoietic, with scarcely developed areas of white pulp. Received: 10 February 1997 / Accepted: 4 May 1997