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。     

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.     

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.     

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.     

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 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.     

Histological and cytological studies on the developing thymus of mandarin fish Siniperca chuatsi (Perciformes: Teleostei)

The thymus of the mandarin fish, Siniperca chuatsi, was examined by light and transmission electron microscopy to understand its formation and cellular composition. Larvae of the mandarin fish were collected and sectioned from 1 to 35 days post‐hatching (dph). On dph 7 the thymus was packed with lymphocytes. From 12 dph onward, mucous cells were observed on the epithelial layer; from 23 dph, three zones could be differentiated in the thymic parenchyma. The thymus was connected with the extension of the third, fourth and fifth branchial pouches throughout early development, remaining in a superficial position in the adult S. chuatsi. In the thymus of the adult fish, thymic epithelial cells (TECs) characteristic of tonofilaments were observed, with limiting TECs (LECs) found in subcapsular, subseptal, perivascular and nurse‐like TECs containing viable intact lymphocytes inside their vacuoles. In addition, three kinds of granulocytes were observed throughout the thymus, and an incomplete blood–thymus barrier was found in the inner zone. Other cell components such as cystic cells, macrophages and plasma cells, were also described in the thymus of the adult S. chuatsi. The thymus development in mandarin fish agrees, to some extent, with the ontogenetic patterns observed in other fish species.     

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.     

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。     

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.     

Analysis of expressed genes in ethylene-treated potato leaves using expressed sequence tags

To isolate useful and interesting plant genes in large quantities, random sequencing of cDNA clones from potato leaf library treated with ethylene was performed. Partial sequences of randomly selected 210 clones with the insert of longer than 500 base pair (bp) as well as poly (A) tail have been compared with sequences in GeneBank, EMBL and DDBJ nucleic acid databases and fostered 193 expressed sequence tags (ESTs). The 210 cDNA clones identified are related to various aspect of metabolic pathways such as glycolysis, amino acid synthesis, translation mechanism, ribosome synthesis, hormone response, stress response, regulation of gene expression, and signal transduction. Among the 193 ESTs, 12 ESTs (29 cDNA clones) appeared more than once and 181 ESTs appeared once regarded as a solitary group. Out of 210 clones, 29 clones (13.8%) have no similarity to the known nucleotide sequences and could serve as a potentially useful resource for plant molecular biology referring to particular genes. Nucleotide sequencing to generate more ESTs from ethylene-induced as well as non-induced potato leaf is in progress as well.     

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...     

EST-based identification of immune-relevant genes from spleen of Indian catfish, Clarias batrachus (Linnaeus, 1758)

A normalized cDNA library from spleen of Indian catfish, Clarias batrachus, was constructed with a redundancy factor of 2.29. A total of 2045 clones from the library were single-pass sequenced, which generated 1937 high quality ESTs with an average read length of approximately 700 bp. Based on sequence similarities, 65 ESTs were found to be associated with immune functions, which were mainly associated with response to stress, response to chemical stimulus, cellular response to stimulus, response to external stimulus, immune response and regulation of response to stimulus. The immune-relevant gene for CD141, thrombomodulin, has been identified in Teleosts for the first time. Six EST-SSRs and three SNPs were found associated with eight immune-relevant genes. These markers associated with important immune genes would be useful for the identification of trait associated alleles for marker-assisted selection. The identification of the putative immune-related genes provides a meaningful framework to understand the Indian catfish immune system and defense mechanisms.     

Short-term thermal acclimation induces adaptive changes in the inner mitochondrial membranes of fish skeletal muscle

In the oxidative muscles (musculi laterales superficiales) of crucian carp Carassius carassius acclimated for 6 weeks to either 5 or 25° C, the volume density and the surface density of fibres per tissue did not differ significantly between the control and experimental groups. The correlation ratio (μ²) for these values was below 50, 39·3 and 43·9 respectively. After acclimation to 5° C, the surface density of outer mitochondrial membrane per fibre increased significantly from 0·93 to 1·23m² cm⁻³ in the summer population but dropped from 0·94 to 0·67 m² cm⁻³ in the winter population. The surface density of outer mitochondrial membrane per mitochondrion increased from 3·24 to 4·52 m² cm⁻³ in summer fish. After acclimation to 25° C, the surface density of inner mitochondrial membranes per muscle fibre decreased from 4·04 to 1·79 m² cm⁻³ in summer fish and from 3·86 to 1·07 m² cm⁻³ in winter fish. The surface density of inner mitochondrial membranes per mitochondrion increased from 14·17 to 15·60 m²cm⁻³ in summer fish but dropped from 13·91 to 10·67 m² cm⁻³ in winter fish. Correlation matrices demonstrate a negative correlation of the surface density of outer mitochondrial membrane per mitochondrion with the volume density of mitochondria per fibre and temperature, suggesting cold-induced proliferation of small mitochondria. It was concluded that short-term cold acclimation increased surface area of the inner mitochondrial membranes in summer fish.     

Genetic population structure in Siniperca scherzeri (Perciformes: Siniperca) in China inferred from mitochondrial DNA sequences and microsatellite loci

This study aims to improve the estimates of fine-scale genetic diversity and to compare the population structure of Siniperca scherzeri with nuclear and mitochondrial DNA (mtDNA) markers. We first combined mtDNA sequences and seven microsatellite loci to examine the genetic diversity of S. scherzeri in China. Phylogenetic and nested clade analyses revealed two major mtDNA lineages and four subclades. Bayesian multilocus genotype clustering from the microsatellite loci revealed that regional divergence estimates were quantitatively congruent between marker classes. These lineages should be recognized as the basic evolutionary significant units for S. scherzeri in China. Contradict to the previous studies on Coreoperca whiteheadi and Siniperca chuatsi, neither the Nanling–Wuyi Mountain range nor the Qingling–Dabie Mountain range represented a major phylogeographic barrier for S. scherzeri. Our fine-scale analyses of the genetic population structure of S. scherzeri provided insights into the evolutionary processes that shaped the genetic heterogeneity of this fish. This study may serve as a basis for the protection, monitoring and breeding improvement of germplasm resources of this commercially important fish.