On the karyosystematics of cyprinid fishes and a summary of fish chromosome studies in China

To date, the chromosomes of 210 species of fresh-water fishes have been studied in China. They are principally cyprinids. Based upon the karyotypic data so far obtained mainly by the authors' laboratory, a report is here submitted on the karyosystematics of Chinese cyprinid fishes.The primitive karyotype of cyprinid fishes may be inferred as being 2n=50. During phyletic evolution the cyprinid fishes probably have been differentiated into two large branches, one of which with the Leuciscinae as a basic group and another branch with the Barbinae as a basic group. As to the modes of their chromosome evolution, Robertsonian translocation seems to be prominent in the first branch, whereas polyploidization appears to be prominent in the second branch. Based on the chromosome studies in cyprinid fishes, some tentative ideas about the classification of the subfamilies in Cyprinidae are presented.A table containing the karyotypes of Chinese fresh-water fishes is attached.This work was partially supported by the Science Fund of the Chinese Academy of Science.     

中国东部沿海中小型河流鱼类的整体遗传多样性评价——以曹娥江为例

研究将曹娥江作为东部沿海中小型河流代表, 基于线粒体细胞色素b基因(Cyt b)分子标记对其鱼类的整体遗传多样性水平进行了评估。结果表明, 21个种26个群体鱼类Cyt b基因的单倍型多样性指数(h)和核苷酸多样性指数(π)水平分别为0.074—0.987和0.00019—0.00520, 物种间遗传多样性水平差异较大; 比较不同江段鱼类遗传多样性水平发现, 曹娥江鱼类的单倍型多样性指数水平从河口到中下游再到上游逐渐降低(P<0.05)。比较同一物种的遗传多样性水平发现, 曹娥江鱼类的核苷酸多样性指数水平低于长江、珠江等大型河流鱼类的相应指数水平(P<0.05), 提示曹娥江鱼类的整体遗传多样性处于中等偏下水平, 鱼类资源亟需科学的保护和修复。进一步分析人为扰动因素对曹娥江鱼类遗传多样性水平的影响发现, 敏感型鱼类的单倍型多样性指数水平显著低于中等耐受型鱼类(P<0.05); 麦穗鱼(Pseudorasbora parva)、光泽黄颡鱼(Pelteobagrus nitidus)和刺鳅(Mastacembelus aculeatus)3种鱼类的上游镜岭群体单倍型多样性指数和核苷酸多样性指数水平均低于其中游仙岩群体的相应指数水平。结果提示, 水体污染、过度捕捞可能是造成目前曹娥江鱼类遗传多样性水平较低的主要原因。研究结果将为曹娥江乃至东部中小河流的鱼类资源的管理、保护和开发利用提供重要的理论依据。     

Phosphoglucomutase electrophoretic patterns of the loach Cobitis biwae

Phosphoglucomutase of two groups of the loach Cobitis biwae , a fresh-water teleost, was examined by starch gel electrophoresis. Some of the fishes had six-banded electrophoretic patterns not observed in other loach species (e.g. Misgurnus anguillicaudatus and Cobitis delicata ). The complexity of the pattern is explainable by an assumption that the loaches are tetraploid fishes. The result suggests that a diploid-tetraploid relationship exists within the species Cobitis biwae .     

Cell volume maintenance and regulation in kidney tissues of various vertebrates

Ouabain-sensitive and ouabain-insensitive mechanisms are shown to participate to a different extent in the cell volume maintenance in kidney tissues of various vertebrates. The ouabain-insensitive mechanisms predominate in the lamprey and in fresh-water fishes, whereas in the flounder, representing sea fishes, there is a complete predominance of the ouabain-sensitive mechanism. In the rabbit kidney cortex tissue the two systems play a comparable role. Analogous inter-species differences are displayed when the cells regulate their volume in anisoosmolar media.     

Molecular diversity analysis of grape varieties based on iPBS markers

Thirty-five grape varieties were evaluated for their molecular diversities based on inter-primer binding site (iPBS) markers. Fifteen selected iPBS primers generated a total of 99 polymorphic DNA bands with 86.3% polymorphism. The effectiveness of iPBS marker is comparable to or even more efficient than other retrotransposon-based markers in grape. The differentiation between cultivated and wild grape varieties were clearly showed by both UPGMA cluster analysis and PCoA analysis revealing that Chinese cultivated and wild grape germplasm are highly divergent and possess abundant genetic diversities. This study also confirmed that the iPBS marker is a simple, informative, reproducible and suitable method for grape genetic diversity evaluation.     

Population genetic structure and effective population size of ayu (Plecoglossus altivelis), an amphidromous fish

The temporal and spatial population genetic structure of ayu Plecoglossus altivelis (Salmoniformes: Plecoglossidae), an amphidromous fish, was examined using analysis of variation at six microsatellite DNA loci. Intracohort genetic diversities, as measured by the number of alleles and heterozygosity, were similar among six cohorts (2001–2006) within a population (Nezugaseki River), with the mean number of alleles per cohort ranging from 11·0 to 12·5 and the expected heterozygosity ranging from 0·74 to 0·77. Intrapopulational genetic diversities were also similar across the three studied populations along the 50 km coast, with the mean number of alleles and the expected heterozygosity ranging from 11·33 to 11·67 and from 0·75 to 0·76, respectively. The authors observed only one significant difference in pair-wise population differentiation ( F _ST-value) between the cohorts within a population and among three populations. Estimates of the effective population size ( N _e) based on maximum-likelihood method yielded small values (ranging from 94·8 to 135·5), whereas census population size ranged from c. 4800 to 24 000. As a result, the ratio of annual effective population sizes to census population size ( N _e/ N ) ranged from 0·004 to 0·023. These estimates of N _e/ N agree more closely with estimates for marine fishes than that of the larger estimates for freshwater fishes. The present study suggests that ayu which is highly fecund and shows low survival during the early life stages is also characterized by having low value of N _e/ N , similar to marine species with a pelagic life cycle.     

Restitution of vimba (Vimba vimba, Cyprinidae) in Poland: genetic variability of existing and restored populations

Until 1960s, vimba was found abundantly in Polish rivers and was an important species for the fishing industry. Overfishing, water pollution and dam constructions brought most of the vimba populations close to extinction. We analyzed the genetic variability of several remnant vimba populations in the Vistula and Oder river basins. The 305-bp fragment encompassing the 5′-end of the mtDNA control region was sequenced in a total of 202 wild specimens derived from six populations. Six different haplotypes were distinguished. The population of Barycz River was found to be the most polymorphic and was chosen as a source of breeding material for the vimba restitution program. In the years 2000–2008 fishes from this river were caught, spawned in captivity and released to the same river. The number of fishes returning to the Barycz River spawning grounds was monitored in the following years. In 2008, it was almost 70 times higher than the number of fishes recorded in 2003, when the lowest population size was observed. The haplotype and nucleotide diversities of the restored population were similar to those of the original population.     

中国大豆疫霉菌遗传多样性的RAPD分析

采用随机扩增多态性DNA(RAPD)技术,利用13个引物对75个中国大豆疫霉菌分离物和11个美国分离物进行PCR扩增。在78个RAPD标记中,多态性标记为68个,占87.2%。RAPD指纹聚类分析表明,当以相异距离0.3为阈值,86个分离物被划为12个RAPD遗传组,其中J组有54个分离物,占总数的62.8%,包括44个中国分离物和10个美国分离物。在中国大豆疫霉菌群体内,多数分离物之间遗传相似性较低,在DNA水平上存在显著的遗传变异,具有较丰富的遗传多样性。RAPD分组结果未表明大豆疫霉菌DNA多态性特征与病原菌毒力基因构成之间和分离物地理来源之间存在相关性,证明中国不同地区的大豆疫霉菌群体在与大豆品种的互作中发生了广泛的遗传变异,具有DNA遗传进化方向和毒力基因演变的多样性。美国大豆疫霉菌分离物间遗传距离较近,而中国分离物在总体上与美国分离物的遗传距离较远,表明中国大豆疫霉菌具有比较独特的遗传背景。     

中国大豆疫霉菌遗传多样性的RAPD分析*

采用随机扩增多态性DNA(RAPD)技术,利用13个引物对75个中国大豆疫霉菌分离物和11个美国分离物进行PCR扩增。在78个RAPD标记中,多态性标记为68个,占87.2%。RAPD指纹聚类分析表明,当以相异距离0.3为阈值,86个分离物被划为12个RAPD遗传组,其中J组有54个分离物,占总数的62.8%,包括44个中国分离物和10个美国分离物。在中国大豆疫霉菌群体内,多数分离物之间遗传相似性较低,在DNA水平上存在显著的遗传变异,具有较丰富的遗传多样性。RAPD分组结果未表明大豆疫霉菌DNA多态性特征与病原菌毒力基因构成之间和分离物地理来源之间存在相关性,证明中国不同地区的大豆疫霉菌群体在与大豆品种的互作中发生了广泛的遗传变异,具有DNA遗传进化方向和毒力基因演变的多样性。美国大豆疫霉菌分离物间遗传距离较近,而中国分离物在总体上与美国分离物的遗传距离较远,表明中国大豆疫霉菌具有比较独特的遗传背景。     

The Ichthyofauna Associated with an Intertidal Creek and Adjacent Eelgrass Beds in the Kariega Estuary,South Africa

The structure and functioning of salt marsh fish communities in the overall ecology of southern African estuaries is poorly understood. This study compares the ichthyofauna associated with a salt marsh creek and eelgrass bed in an attempt to evaluate the relative importance of these habitats to fishes. Taylor's salt marsh creek and adjacent eelgrass bed in the Kariega Estuary were sampled twice per season between the winter of 1992 and the autumn of 1994. The average density and standing stock of fishes were found to be considerably higher in the eelgrass bed than in the intertidal creek. Both habitats had similar fish diversities but were dominated by different taxa, the most notable of which was the dominance of mugilids in the creek and their scarcity in the eelgrass. Taylor's intertidal creek and adjacent eelgrass beds were dominated by juvenile fish, with both habitats functioning as nursery areas for juvenile fish, albeit for totally different ichthyofaunal communities. The similar fish diversities but lower abundances in the intertidal creek compared to the eelgrass beds are in contrast to similar North American studies, and refute the hypothesis that intertidal salt marsh creeks have higher fish densities but lower diversities than eelgrass beds.The first author is also the senior author     

PCR-DGGE对长江河口八种野生鱼类肠道菌群多样性的比较研究

目的分析长江河口捕获的8种野生鱼类的肠道菌群多样性的差异并观察这种差异与食性的联系。方法采用PCR-DGGE(denaturing gradient gel electrophoresis)技术,DGGE图谱用PCA(principal component analy-sis)方法进行分析。结果建立了长江口8种鱼野生条件下肠道菌群的DGGE指纹图谱,观察到它们在野生条件下的肠道菌群的差异。其中,营底栖生活的舌鰕虎鱼的肠道菌群和其他7种野生鱼有着明显的差异,其他7种鱼的肠道菌群多样性的差异与它们的食性差异相关。结论PCR-DGGE技术是一种能够快速有效地分析研究鱼类肠道菌群结构的技术。8种野生鱼的肠道菌群的结构有明显的差别,并且食性差异大的鱼类之间肠道菌群差异也     

Vertebrates and the Permo-Triassic extinction

The fossil record of vertebrates in the late Paleozoic and early Mesozoic is investigated in an attemp to evaluate their participation in the Permo-Triassic faunal crisis. On the whole the record of the marine fishes is similar to that of marine invertebrates with a pronounced diversity minimum at the end of the Permian. On the other hand, the fresh-water and euryhaline fishes, together with the amphibians, seem to have experienced minimal diversity somewhat earlier in the Permian and apparently were on the increase at the Permo-Triassic boundary. The major peculiarity in the reptilian record is a great burst of both first appearances and apparent extinctions in the Dzhulfian Stage in Africa; local causes are suspected. Seemingly the Permo-Triassic faunal crisis was mainly a marine event for which a marine cause or causes should be sought.     

Analysis of diversity and genetic relationships between four Chinese indigenous pig breeds and one Australian commercial pig breed

The genetic diversities and relationships of four Chinese indigenous pig breeds and one Australian commercial pig breed have been evaluated using 27 microsatellites recommended by the International Society of Animal Genetics (ISAG) and the Food and Agriculture Organization (FAO). The allele frequencies, effective numbers of alleles and the polymorphic information content have been calculated. Nei's standard genetic distances have been used to construct a UPGMA dendrogram, which has been evaluated by the Bootstrap test. The utility of microsatellites for evaluating genetic diversity of pigs is discussed.     

Ecological succession among late palaeozoic and mesozoic tetrapods

Natural selection and the development of new taxa are associated with ecological replacement and the increase in number of niches with time. Continental faunal interchange was possible globally because of the existence of the super-continent Pangaea during much of the Upper Palaeozoic and Mesozoic. Figures of tetrapod niches vs. time and discussion of this concept for that period are presented for the first time. Four habitat divisions are used, namely marine, fresh-water, lowland and upland.The marine habitat was colonised rather late by tetrapods and these may have been the first predators on the early bony fishes which had diversified in the Permian. The radiation of bony fishes in the Jurassic was followed by a further increase in variety of their reptilian predators. Predators seem to develop some time after the radiation of a new potential prey group.Most early amphibians occupied fresh-water habitats in “crocodile” or “frog” niches, but from the Triassic tetrapods moved from fresh-waters and lowlands into the uplands also.In terrestrial habitats, the replacement of mammal-like reptiles by dinosaurs is tentatively explained in terms of palaeoclimatology and thermoregulatory physiology. Ornithischians capable of dealing with tough vegetation evolved to occupy the new niches produced by the radiation of conifers in the Jurassic. The extinction of dinosaurs appears to have been connected with temperature and habitat changes.Conclusions are supported by a summary of published opinions on the palaeoecological roles of early tetrapods.     

Phosphatases in the accessory respiratory organs of two fresh-water fishes.

The distribution of enzymes, viz., alkaline phosphatase, acid phosphatase, adenosine monophosphatase and adenosine triphosphatase was studied by histochemical methods in the accessory respiratory organs of two fresh-water fishes (Clarius batrachus and Heteropneustes fossilis). Enzymes have been used as markers to differentiate between functional and non-functional cells of the dendritic organ of Clarius and of the air chamber of Heteropneustes. The variations in the enzyme activities have been correlated with the functional capacity of each respiratory organ. It is attempted to understand the physiological role of these enzymes in the process of aerial breathing.     

SRAP标记在植物遗传多样性中的应用进展

该文综述了SRAP标记在植物种类遗传多样性国内近几年的应用进展,以便为今后的研究提供相应的理论依据.同时,并讨论了一些SRAP标记在植物种类遗传多样性应用中尚存在的问题.     

Metabolic activity in the saccus vasculosus of the rainbow trout,salmo gairdneri (richardson)

Summary Labelling experiments to test mucopolysaccharide synthesis in the saccus vasculosus of the rainbow trout gave negative results and provoked analysis of succinic dehydrogenase activity in the coronet cells. Such activity was almost absent in the fresh-water living rainbow trout but was intense in sea water adapted individuals as well as in a sea water teleost, the flounder. Conversely, in sea water adapted rainbow trout which had been transferred back to fresh-water, activity had again decreased. In the sea water adapted rainbow trout high succinic dehydrogenase activity was paralleled by strongly positive staining with alcian blue, indicating the presence of mucopolysaccharides. The latter fishes also showed incorporation of N-acetyl-³H-glucosamine. Our findings indicate a role for saccus vasculosus in adaptation for osmoregulation in sea water and favour the hypothesis of a secretory function for the coronet cells.This work has been supported by grants from the Royal Physiographical Society of Lund and the Faculty of Natural Sciences at the University of Lund. We are greatly indebted to Mrs. Lena Eriksson, Mrs. Kristine Fogelström and Mrs. Lena Svenre for excellent technical assistance.     

Random expression of main and vomeronasal olfactory receptor genes in immature and mature olfactory epithelia of Fugu rubripes

Main olfactory receptor genes were isolated from a seawater fish, Fugu rubripes (pufferfish), and characterized. Two subfamilies of genes encoding seven transmembrane receptors were identified; one consists of five or more members, termed FOR1-1 to 5 of FOR1 subfamily, and the other appears to be a single copy gene, termed the FOR2 subfamily. FOR1 members show extremely high amino acid sequence similarities of about 95% to one another, and are distantly related to catfish-1 with the highest similarity of 37%. FOR2 shows 43% similarity to goldfish-A28. Phylogenically, both FOR members are categorized among pedigrees of the fish main olfactory receptor family outside the mammalian receptor family, although similarities between Fugu receptors and those of fresh-water fishes are lower than those among fresh-water fishes. In situ hybridization shows that both subfamilies of receptor genes are expressed randomly over the olfactory epithelium throughout all developmental stages, and no segregation of the signals was found. On the other hand, when three members of a vomeronasal olfactory receptor gene family, related to the Ca(2+)-sensing receptor, were used as probes, they were also randomly expressed over the same epithelium as the main olfactory receptors. This is in contrast to the expression profiles observed for zebrafish and goldfish, where the main or vomeronasal olfactory receptors are expressed in segregated patterns. It is thus suggested that the expression pattern of fish olfactory receptors varies depending on the species, although fish olfactory receptors are highly related to one another in their primary structures, and are phylogenically distinct from those of mammals.     

Genetic population structure of the endemic fourline wrasse (Larabicus quadrilineatus) suggests limited larval dispersal distances in the Red Sea

The connectivity among marine populations is determined by the dispersal capabilities of adults as well as their eggs and larvae. Dispersal distances and directions have a profound effect on gene flow and genetic differentiation within species. Genetic homogeneity over large areas is a common feature of coral reef fishes and can reflect high dispersal capability resulting in high levels of gene flow. If fish larvae return to their parental reef, gene flow would be restricted and genetic differentiation could occur. Larabicus quadrilineatus (Labridae) is considered as an endemic fish species of the Red Sea and Gulf of Aden. The juveniles of this species are cleaner fish that feed on ectoparasites of other fishes. Here, we investigated the genetic population structure and gene flow in L. quadrilineatus among five locations in the Red Sea to infer connectivity among them. To estimate genetic diversity, we analysed 369 bp of 237 mitochondrial DNA control region sequences. Haplotype and nucleotide diversities were higher in the southern than in the northern Red Sea. Analysis of molecular variance (amova) detected the highest significant genetic variation between northern and central/southern populations (Phi(CT) = 0.01; P < 0.001). Migration analysis revealed a several fold higher northward than southward migration, which could be explained by oceanographic conditions and spawning season. Even though the Phi(ST) value of 0.01 is rather low and implies a long larval dispersal distance, estimates based on the isolation-by-distance model show a very low mean larval dispersal distance (0.44-5.1 km) compared to other studies. In order to enable a sustainable ornamental fishery on the fourline wrasse, the results of this study suggest that populations in the northern and southern Red Sea should be managed separately as two different stocks. The rather low larval dispersal distance of about 5 km needs to be considered in the design of marine protected areas to enable connectivity and self-seeding.