Natural infections of Clinostomum complanatum (Trematoda: Clinostomatidae) in wild herons and egrets, Tottori Prefecture, Japan.

Nycticorax nycticorax, Ardea cinerea, Egretta garzetta, and Egretta intermedia were naturally infected with Clinostomum complanatum (Trematoda: Clinostomatidae) among fourteen wild herons, seven wild egrets and one wild bittern evaluated at the Veterinary Hospital of Tottori University, Tottori, Japan. The latter three species of heron and egrets are reported for the first time as definitive hosts of this parasite in Japan.     

The first record of spawning-season homing of gin-buna crucian carp Carassius sp. to a lakeside biotope connected to Lake Biwa confirmed via acoustic telemetry and egg surveys

Ichthyological Research - Gin-buna crucian carp Carassius sp. is a widely distributed cyprinid fish inhabiting lakes and rivers throughout Japan. The species is categorized on the Red List of Shiga...     

Isolation and characterization of microsatellite markers from Fangzheng silver crucian carp,Carassius auratus gibelio (Bloch), and cross‐amplification in the closely related species crucian carp,Carassius auratus auratus (Linnaeus)

We report the development of 20 microsatellite markers for Fangzheng silver crucian carp, Carassius auratus gibelio (Bloch). Nineteen out of 20 showed polymorphism with alleles ranging from two to 14. These loci were screened to amplify the closely related species crucian carp, Carassius auratus auratus (Linnaeus) and all of them can amplify DNA with the size similar to the former. The origin of silver crucian carp is in issue and the population genetic structure is still unclear. Microsatellite markers isolated from the silver crucian carp and their utility in the crucian carp will be useful for these researches.     

Massive production of all-female diploids and triploids in the crucian carp

In many species of aquaculture importance, all-female and sterile populations possess superior productivity due to faster growth and a relatively homogenous size of individuals. However, the production of all-female and sterile fish in a large scale for aquaculture is a challenge in practice, because treatments necessary for gynogenesis induction usually cause massive embryonic and larval mortality, and the number of induced gynogens is too small for their direct use in aquaculture. Here we report the massive production of all-female triploid crucian carp by combining artificial gynogenesis, sex reversal and diploid-tetraploid hybridization. Previously, we have obtained an allotetraploid carp population (4n = 200) by hybridization between red crucian carp (Carassius auratus red var; ♀) and common carp (Cyprinus carpio; ♂). We induced all-female diploid gynogens of the Japanese crucian carp (Carassius cuvieri; 2n = 100). We also generated male diploid gynogens of the same species treated gynogenetic fry with 17-α-methyltestosterone, leading to the production of sex-revered gynogenetic males. Finally, these males were used to cross with the female diploid Japanese crucian carp gynogens and the allotetraploid females, resulting in the production of fertile all-female diploid Japanese crucian carp (2n=100) and sterile all-female triploid hybrids (3n = 150), respectively. Therefore, diploid crucian carp gynogenetic females and sex-reversed male together with an allotetraploid line provide an opportunity to produce all-female triploid populations in a large scale to meet demands in aquaculture industry.     

Evidence for the paternal mitochondrial DNA in the crucian carp-like fish lineage with hybrid origin

In terms of taxonomic status, common carp(Cyprinus carpio, Cyprininae) and crucian carp(Carassius auratus, Cyprininae) are different species; however, in this study, a newborn homodiploid crucian carp-like fish(2n=100)(2nNCRC) lineage(F1–F3) was established from the interspecific hybridization of female common carp(2n=100)×male blunt snout bream(Megalobrama amblycephala, Cultrinae, 2n=48). The phenotypes and genotypes of 2 n NCRC differed from those of its parents but were closely related to those of the existing diploid crucian carp. We further sequenced the whole mitochondrial(mt) genomes of the 2n NCRC lineage from F1 to F3. The paternal mt DNA fragments were stably embedded in the mt-genomes of F_1–F_3 generations of 2n NCRC to form chimeric DNA fragments. Along with this chimeric process, numerous base sites of F1–F3 generations of 2 n NCRC underwent mutations. Most of these mutation sites were consistent with the existing diploid crucian carp. Moreover, the mt DNA organization and nucleotide composition of 2n NCRC were more similar to those of the existing diploid crucian carp than those of the parents. The inheritable chimeric DNA fragments and mutant loci in the mt-genomes of different generations of 2nNCRC provided important evidence of the mt DNA change process in the newborn lineage derived from hybridization of different species. Our findings demonstrated for the first time that the paternal mt DNA were transmitted into the mt-genomes of homodiploid lineage, which provided new insights into the existence of paternal mt DNA in the mt DNA inheritance.     

三种鲫鱼品系同工酶比较研究

采用聚丙烯酰胺凝胶垂直板电泳技术,对彭泽鲫、银鲫D系以及野鲫三种鲫鱼品系的心、肝和肾脏组织的乳酸脱氢酶(LDH)、苹果酸脱氢酶(MDH)、苹果酸酶(ME)、酯酶(EST)和超氧化物歧化酶(SOD)同工酶表型进行了比较研究.结果表明彭泽鲫乳酸脱氢酶同工酶比银鲫D系在肝组织多出二条酶带(LDH7'和LDH8');超氧化物歧化酶在心和肾组织中分别多出一条酶带(SOD12'),表明彭泽鲫和银鲫已在生化水平产生明显的分化,推测它们可能起源于不同的地区,由不同的祖先,独立演化而形成.此外,彭泽鲫和银鲫D系的同工酶电泳图谱都包含野鲫的基本酶带,而彭泽鲫和野鲫的酯酶同工酶电泳图谱尤为相似,推测彭泽鲫和银鲫可能起源于野鲫,而彭泽鲫和野鲫的关系较近,银鲫和野鲫的关系较远.     

Genetic diversity analysis of crucian carp (Carassius auratus) based on cyt b and D-loop-containing region around Hongze Lake

Environmental Biology of Fishes - Crucian carp (Carassius auratus) is an important freshwater aquaculture species in China. The study of the genetic diversity of native crucian carp will provide...     

复合四倍体异育银鲫两种不同生殖方式的细胞学观察

在复合四倍体异育银鲫（）×银鲫（）的受精过程中,精子入卵后经过解凝、核化,最终形成雄性原核,并可与卵子的雌性原核融合,证明了复合四倍体异育银鲫卵子具有与两性融合生殖极为相似的拟两性融合生殖的能力;而在复合四倍体异育银鲫（）×兴国红鲤（）的组合中,精子入卵后以固缩状态存在,又表现出典型的雌核发育型生殖行为。因此我们认为复合四倍体异育银鲫具有两种不同的生殖发育机制。此外,我们还观察到在第一次有丝分裂中期有核物质被排斥到纺锤体之外的现象。本文就复合四倍体异育银鲫生殖发育的机制进行了初步的探讨。     

A Set of Polymorphic Trinucleotide and Tetranucleotide Microsatellite Markers for Silver Crucian Carp (Carassius auratus gibelio) and Cross-Amplification in Crucian Carp

Silver crucian carp (Carassius auratus gibelio Bloch), as a gynogenetic fish, is a promising model for the study of the evolutionary genetics of vertebrates. We have developed 59 polymorphic trinucleotide and tetranucleotide markers for the silver crucian carp through the biotin capture method and radioactive-labeling hybridization. The number of alleles ranged from 2 to 12 in the population, and the average proportion of heterozygotes (including tri- and diallelic) at polymorphic loci was 76.8%. In addition, these loci were successfully applied to a close relative, the crucian carp (Carassius auratus), by cross-amplification, as shown by the range of alleles (2–19), observed heterozygosity (0.1765–0.9706), expected heterozygosity (0.2392–0.9421), and polymorphism information content (0.2186–0.9236).     

Predator-induced morphology enhances escape locomotion in crucian carp

Fishes show a remarkable diversity of shapes which have been associated with their swimming abilities and anti-predator adaptations. The crucian carp (Carassius carassius) provides an extreme example of phenotypic plasticity in body shape which makes it a unique model organism for evaluating the relationship between body form and function in fishes. In crucian carp, a deep body is induced by the presence of pike (Esox lucius), and this results in lower vulnerability to gape-limited predators, such as pike itself. Here, we demonstrate that deep-bodied crucian carp attain higher speed, acceleration and turning rate during anti-predator responses than shallow-bodied crucian carp. Therefore, a predator-induced morphology in crucian carp enhances their escape locomotor performance. The deep-bodied carp also show higher percentage of muscle mass. Therefore, their superior performance in escape swimming may be due to a combination of higher muscle power and higher thrust.     

Genetic polymorphism and isoenzyme patterns of lactate dehydrogenase in tench (Tinca tinca), crucian carp (Carassius carassius) and carp (Cyprinus carpio)

Isoenzyme patterns and the polymorphism of lactate dehydrogenase (LDH) were investigated in 3 fish species of family Cyprinidae, i.e. tench (Tinca tinca), crucian carp (Carassius carassius) and carp (Cyprinus carpio). The isoenzyme patterns were tissue and species specific. In crucian carp subunits with different electrophoretic mobility are present, which are genetically controlled from the B1, B2, A1, A2 and C loci, while the set of loci in carp is B1, B2, A, C1 and C2 and in tench B, A, C. The locus B of LDH in tench, the locus B2 in crucian carp, and the loci B1, C1 and C2 in carp are polymorphic and have two different alleles in each case. The polymorphism did not affect the total LDH activity in the tissues. All the populations investigated were in Hardy-Weinberg equilibrium. The genetic control of the polymorphism in B1 and C1 loci in carp was proved by test matings. The polymorphism in B loci tested in erythrocytes may be utilized as genetic markers in the fish breeding.     

Koi herpesvirus infection in experimentally infected common carp Cyprinus carpio (Linnaeus, 1758) and three potential carrier fish species Carassius carassius (Linnaeus, 1758); Rutilus rutilus (Linnaeus, 1758); and Tinca tinca (Linnaeus, 1758) by quantitative real‐time PCR and in‐situ hybridization

Only single cells in the carrier fish species Carassius carassius (Linnaeus, 1758) for koi herpesvirus (KHV) are infected in contrast to large numbers in the susceptible species common carp Cyprinus carpio (Linnaeus 1758). Several species of the family Cyprinidae have been described as virus carrier species, showing no clinical signs of a KHV disease but able to transmit the virus to other susceptible fish. In this study, 72 common carp Cyprinus carpio (Linnaeus, 1758), 36 tench Tinca tinca (Linnaeus, 1758), 36 crucian carp Carassius carassius (Linnaeus, 1758) and 36 common roach Rutilus rutilus (Linnaeus, 1758) were experimentally infected with KHV (isolate “Israel”) by immersion and kept at 20°C. The fish were euthanized at 12 timepoints over a period of 90 days and virus DNA was quantified in tissues by a real‐time TaqMan PCR. Whereas KHV‐DNA was found in Cyprinus carpio for up to 90 days, the virus DNA was detectable only in single individuals of Rutilus rutilus, Tinca tinca and Carassius carassius for up to 25 days after experimental virus exposure. Tissue samples of Cyprinus carpio and Carassius carassius were screened by in‐situ hybridization. Positive signals were found in various organs of the common carp tested crucian carp. In the latter species a much smaller number of virus‐positive stained cells was detected compared to the infected carp.     

Difference in the hypoxia tolerance of the round crucian carp and largemouth bass: implications for physiological refugia in the macrophyte zone

The hypoxia tolerance of larval and juvenile round crucian carp, Carassius auratus grandoculis, and largemouth bass, Micropterus salmoides, was determined using respirometry to examine the potential of hypoxic areas in the macrophyte zone as physiological refugia for round crucian carp. The tolerance, which was measured as the critical oxygen concentration (Pc), was 1.32 mg O₂/l in the round crucian carp and 1.93 mg O₂/l in the largemouth bass. As the round crucian carp tolerated hypoxia better than the largemouth bass, hypoxic areas in the macrophyte zone might function as physiological refugia for round crucian carp.     

新疆伊犁河鲫鱼遗传多样性初步研究

为了解我国西北地区野生鲫鱼的遗传多样性,鲫鱼样品从新疆伊梨河中采用小型拖网捕获。通过解剖观察性腺鉴定性别;采用碘化丙啶（PI）染色,经流式细胞仪测定血细胞核DNA含量;采用非变性聚丙烯酰胺凝胶电泳,考马斯亮蓝染色分析血清转铁蛋白多态性。结果表明：新疆伊梨河鲫鱼群体为具雌、雄的两性个体的群体;伊犁河鲫鱼血细胞核DNA平均含量为(5.315±0.215) pg/个细胞核,血细胞核DNA含量约为二倍体彩鲫DNA含量的1.53倍,与银鲫血细胞核DNA含量相当;在所采集的鲫鱼样品中共发现9种转铁蛋白表现型, 由7个等位基因调控,等位基因频率依次为Tf a0.063、Tf b0.063、Tf f0.095、Tf g0.169、Tf c0.174、Tf e0.175和Tf d0.270。基因型频率分别为Tf cd0.043、Tf cdf0.043、Tf abdg0.043、Tf def 0.087、Tf ce0.13、Tf de0.13、Tf df0.13、Tf abeg0. 13和Tf cdg0.26。综合分析,伊犁河现存野生鲫鱼为银鲫,且具有两性融合生殖能力。伊犁河鲫鱼表现出的遗传特性可能与该特定水环境有关。     

异源精子在银鲫雌核发育子代中的生物学效应

黑龙江省方正县双凤水库的两性型银鲫群体是三倍体雌核发育种群。异源精子不仅能刺激银鲫卵雌核发育,而且还能影响雌核发育子代的某些性状,如对于子代的生长、性比、体色和肝脏LDH同工酶等都产生了影响。为区别于原有术语“雌核发育gynogenesis”,我们把这种表现了异源精子生物学效应的雌核发育称之为“异精雌核发育allogynogenesis”,发育的子代称之为“异育银鲫”。异育银鲫已以其明显的生长优势在生产上显示了优良的经济性状。       

四类不同倍性鲫鱼在胚胎发育期间同工酶基因表达的比较分析

Isozyme zymograms of esterase (EST), lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and superoxide dismutase (SOD) were analysed by polyacrylamide gradient gel electrophoresis at different developmental stages of embryogenesis in 4 types of various ploidy crucian carp embryos, including haploids, diploids, natural triploids, and multiple tetraploids, and 2 types of haploid and diploid common carp embryos. Haploid embryos of crucian carp (Carassius auratus) and common carp (Cyprinus carpio) were produced by treating eggs with UV-irradiated milt from blunt snout bream (Megalobrama amblycephala). Natural triploid embryos were obtained from the eggs of gynogenetic silver crucian carp (Carassius auratus gibelio) inseminated with milt from red common carp. Multiple tetraploid embryos were also produced by gynogenesis from eggs of the newly discovered multiple tetraploid females inseminated with milt from red common carp. Gradient gel electrophoresis indicated that the band types and staining intensity of 4 isozymes expressed in haploid embryos of crucian carp and red common carp were similar to that in the correlative diploid embryos. In natural triploid silver crucian carp embryos, the zymograms of MDH and SOD isozymes were identical with that of diploid crucian carp embryos, but the EST and LDH isozymes manifested more new enzyme bands in comparison with diploid embryos. The corresponding expressed products of some bands in the triploid embryos, such as EST5 and EST6, could be observed also in red common carp embryos, which provided evidence for hybrid origin about the gynogenetic fish. The multiple tetraploids incorporated one foreign genome of red common carp, therefore, the effects of genes from the foreign genome could be observed in the multiple tetraploid embryos. Gene expression of the isozymes in the tetraploid embryos was somewhat similar to that in hybrids. Owing to interaction of triploid silver crucian carp genomes and common carp haploid genome, some isozyme bands, such as EST5 and EST6, changed in quantity, and some bands increased, such as s-SOD1, s-SOD2, s-SOD3 and s-SOD4 in the tetraploid embryos. Moreover, the heterogeneity was revealed among embryos developed from gynogenetic eggs of 3 different multiple tetraploid individuals.     

银鲫与彩鲫卵母细胞cDNA文库构建及周期蛋白A1的cDNA克隆

分别取行天然雌核发育繁殖的银鲫和两性生殖的彩鲫的卵母细胞为材料,提取总RNA,分离mRNA,进而反转录合成cDNA并定向插入λgtll Sfi-Not克隆载体,经体外包装构建了银鲫与彩鲫卵母细胞的表达型cDNA文库。测试结果表明库容量分别达到3.1×106(银鲫)和1.6×106(彩鲫)。进一步人工合成Cyclin A1保守引物,采用PCR扩增文库的方法,克隆了银鲫(1616bp)与彩鲫(1626bp)的Cyclin A1全长cDNA。序列分析结果表明:两种鱼编码区长度均为1173bp,起始于一个包含在脊椎动物起始密码子ANNATG基元内ATG的单一开放读码框,编码391个氨基酸;5'-端非编码区长度也同为70bp,3-'端非编码区长度略有不同,银鲫为373bp,而彩鲫则为383bp;二者3'-端均带有AATAAA的Poly(A)加尾信号以及24bp(银鲫)和27bp(彩鲫)的Poly(A)尾巴。比较银鲫、彩鲫和金鱼与人、爪蟾Cyclin A1氨基酸序列同源性的结果表明,Cyclin A1在人、爪蟾与鱼类之间具有较高同源性;而在银鲫、彩鲫和金鱼之间,Cyclin A1仅在周期蛋白框外存在5个氨基酸的差异,且这些差异均是由个别碱基的变异造成的。       

Body morphology of crucian carp Carassius carassius in lakes with or without piscivorous fish

Crucian carp Carassius carassius was sampled during 1993 and 1994 in 21 lakes and ponds in east Norway In 10 of these lakes and ponds no piscivorous fish species was present, and in the remaining 11 lakes and ponds predators such as perch Perca fluvtalilis. pike Esox lucius, and trout Salmo trutta were common In general, crucian carp was larger in the lakes with predators than in those without predators The relative body depth (body height/body length) of crucian carp was significantly deeper in populations sympatric with predators (mean 0 358), compared to allopatric populations (mean 0 286) The variation in relative body depth was larger among the sympatric populations than among the allopatric populations The observed difference in relative body depth may be due to 1) predator induced changes m body morphology, 2) increased growth rates in lakes containing predator due to reduced intraspecific competition, and 3) size-selective predation     

Five confirmed human cases of gnathostomiasis nipponica recently found in northern Japan.

Five confirmed human cases of gnathostomiasis nipponica exhibiting creeping eruption and itching were found sporadically from the autumn of 1991 to the winter of 1992 in the northern region of the mainland of Japan. In all cases, a causative gnathostome with 3 transverse rows of hooklets on the head bulb was detected in biopsied skin. The morphological characteristics agreed with the advanced third-stage larvae of Gnathostoma nipponicum. Within a few weeks before development of symptoms, all patients had histories of eating raw freshwater fishes, kokanee (Salmo nerka nerka), carp (Cyprinus carpio), crucian carp (Carassius gibelio langsdorfi), or common ice-fish (Salangichthys microdon). However, they had never eaten raw loach, which is known as a source of human infections with G. nipponicum.