魚類学雑誌
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57 巻 , 2 号
選択された号の論文の12件中1~12を表示しています
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本論文
  • 原 政子, 仲村 茂夫, 北野 忠, 秋山 信彦
    57 巻 (2010) 2 号 p. 93-103
    公開日: 2014/03/06
    ジャーナル フリー
    Abstract Ultrastructural observations of spermiogenesis in two paedomorphic gobioid fishes, Schindleria sp. and Leucopsarion petersii, were discussed with special reference to the specialized morphology of their spermatozoa. In Schindleria sp., spermiogenesis was characterized by (1) apical vesicle generated from nuclear section and surrounded by cytoplasm, (2) flagellum implanted to centriole at base of nucleus, moving towards apical vesicle by piercing nucleus center to beyond nucleus tip, (3) apical vesicle spermatozoon subsequently disappearing, (4) nucleus of mature spermatozoon cylindrical, 3.2m m in length and ca. 0.5m m in width, (5)flagellum fully penetrating nucleus, resulting in sperm length equaling flagellum length and (6) single mitochondrion located at base of flagellum in contact with posterior end of nucleus. In Leucopsarion petersii, spermiogenesis was characterized by (1) a mass of small vesicles at nucleus tip forming apical point, (2) elongated apical point based on four rounded corners on top of ovoidal nucleus, (3) two centrioles located on basal body of nucleus, each with a typical flagellum, (4) both flagella with 92 axoneme pattern and (5) mitochondria varying in size and shape coalesce into a long midpiece. The spermatozoa of both species bear extremely specialized structures, such as the apical vesicle and the apical point, not yet reported in other teleosts. These structures are likely to have evolved within the less restricted framework of sperm morphology of gobioids, as reflected in the unusually high species diversity of this group.
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  • 竹野 誠人, 柏木 祥平
    57 巻 (2010) 2 号 p. 105-112
    公開日: 2014/03/06
    ジャーナル フリー
    Morphological and genetical analyses revealed a spined loach population from Tango District, Kyoto Prefecture, to be an allotetraploid form of Cobitis striata. The former had distinctive differences in body coloration and mitochondrial DNA sequences from another allotetraploid form of Cobitis striata, found inLake Biwa, and is tentatively termed the ‘Tango tetraploid form’ of C. striata.
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  • 高田 未来美, 立原 一憲, 西田 睦
    57 巻 (2010) 2 号 p. 113-123
    公開日: 2014/03/06
    ジャーナル フリー
    Carassius auratus in the Ryukyu Archipelago includes both indigenous and introduced populations which can be discriminated from each other by mitochondrial DNA (mtDNA) haplotyping. MtDNA haplotyping of 485 fish from38 water systems on 11 islands within the Archipelago, showed them to comprise254 (52%) indigenous and 231 (48%) introduced individuals. Indigenous specimens were widespread throughout the Ryukyus, mainly inhabiting natural water systems. Introduced specimens were encountered sporadically, mainly in artificial water systems, especially in reservoirs. Ploidy examination by flow cytometry showed that indigenous populations comprised only diploid or diploid and triploid fish, whereas introduced populations often comprise only triploids. The fact that C. auratus was not found on some islands surveyed, despite their former presence being confirmed, suggested recent decreases of C. auratus and highlighted the importance of future conservation of indigenous Ryukyuan C. auratus.
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  • 清水 孝昭, 高木 基裕
    57 巻 (2010) 2 号 p. 125-134
    公開日: 2014/03/06
    ジャーナル フリー
    Variations in genetic and morphological characteristics were investigated in two populations of the exotic pond loach, Paramisgurnus dabryanus, which has invaded rice fields in Kuma-kougen Town, Ehime Prefecture. A sequence analysis of the mitochondrial DNA control region of 46 individuals collectedf rom two sampling sites (Higashi-myoujin and Koudono, separation distance1.6 km) revealed two divergent clades (average nucleotide divergence: 15%)representing separate introductions: Group 1 (four haplotypes), related to P. dabryanus, and Group 2 (two haplotypes), related to Misgurnus anguillicaudatus, as a result of mitochondrial DNA introgression. In 29 of the 46 specimens, which included individuals of both genetic clades, four of 13 morphological characteristics(relative to body size) (head length, pre-pectoral length, dorsal fin base length and caudal peduncle depth) differed significantly (ANOVA, df 28, P 0.01-0.05)between populations, but not between genetic clades. Haplotype constitutions differed significantly between sampling sites (exact test, P 0.001), diversities being greater in Koudono which is located downstream of Higashi-myoujin. The existence of genetically divergent clades among the specimens suggested that the early introductions of this species to Japan originated from several localities.
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  • 水野 敏明, 大塚 泰介, 金尾 滋史, 小川 雅広, 舟尾 俊範, 前畑 政善
    57 巻 (2010) 2 号 p. 135-142
    公開日: 2014/03/06
    ジャーナル フリー
    Environmental factors affecting the preference of branch drainage ditches by round crucian carp (Carassius auratus grandoculis), a Lake Biwa endemic subspecies, were analyzed, fish often ascending to paddy fields, via drainage ditches, for spawning. A logistic regression analysis to determine facors influencing, drainage ditch selection showed dissolved oxygen to be significant, whereas turbidity and water velocity were not. Nevertheless, differences in distribution between ditches selected or not selected for spawning suggested that greater water velocity and moderate turbidity were also important factors.
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