Ken-ichi Numachi
Tokai University
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Featured researches published by Ken-ichi Numachi.
Ichthyological Research | 1996
Yoshikazu Nagata; Tadashi Tetsukawa; Takanori Kobayashi; Ken-ichi Numachi
Eleven populations of the rosy bitterling,Rhodeus ocellatus, from different localities in Japan, were genetically compared at 16 protein-coding loci using starch-gel electrophoresis. Two loci,Ldh-2 andPgdh, were demonstrated as diagnostic markers for the identification of two subspecies;R. ocellatus kurumeus, which is native to Japan, andR. ocellatus ocellatus, which was introduced from China. The two subspecies were distinguished by the complete substitution of different alleles between them. Population ofR. ocellatus kurumeus occurring in Yao City, Osaka, and in Kanzaki, Saga Prefecture were genetically closely related to each other (genetic distance: D=0.056) but distantly so toR. ocellatus ocellatus from Saitama Prefecture (D=0.202 or 0.265). Electrophoretic analyses also elucidated the existence of hybrid populations of the two subspecies. The populations ofR. ocellatus kurumeus in Yao City had lower genetic variability and a lower incidence of white coloration on the ventral fins than populations of the same in Saga Prefecture. The present study strongly implies that the introduction of the foreign freshwater fishes with subspecific differentiation, into the original range of indigenous subspecies, should be averted not to bring the genetic pollution.
Zoological Science | 2003
Hiroyuki Sasaki; Ken-ichi Numachi; Mikhail A. Grachev
Abstract The origin and genetic relationships of the Baikal seal, Phoca sibirica, were studied by restriction fragment length polymorphism analysis of mitochondrial DNA (mtDNA). Using 17 different six-base recognition restriction endonucleases, we examined 98 Baikal seals, and two other related species, the ringed seal, P. hispida, (n=87), and the Caspian seal, P. caspica, (n=94). Analysis revealed the existence of 87 mtDNA haplotypes in the total of 279 specimens. The haplotypes of each species were divided into different clusters on a dendrogram obtained by UPGMA based on haplotype frequency and mtDNA base substitution. No common haplotypes were found among the species examined. The Baikal seal is much more closely related to the ringed seal than the Caspian seal. The amount of divergence suggested that an ancestor of the Baikal seal came down to the lake approximately 0.4 million years ago as was previously indicated by paleontological studies. The seals examined here showed lower variabilities.
Genetics | 1997
Nika Yamazaki; Rei Ueshima; Jonathan A. Terrett; Shin-ichi Yokobori; Masayuki Kaifu; Ryoko Segawa; Takanori Kobayashi; Ken-ichi Numachi; Takuya Ueda; Kazuya Nishikawa; Kimitsuna Watanabe; Richard H. Thomas
Aquatic Living Resources | 2004
Hideyuki Imai; Jin-Hua Cheng; Katsuyuki Hamasaki; Ken-ichi Numachi
Fisheries Science | 1999
Hideyuki Imai; Yoshihiro Fujii; Junichi Karakawa; Shozo Yamamoto; Ken-ichi Numachi
Zoological Science | 1993
Kazuo Mashiko; Ken-ichi Numachi
Zoological Science | 1988
Naoto Hanzawa; Nobuhiko Taniguchi; Ken-ichi Numachi
Aquaculture Science | 2002
Hideyuki Imai; Yasuhiro Obata; Sachio Sekiya; Tomohito Shimizu; Ken-ichi Numachi
Canadian Journal of Fisheries and Aquatic Sciences | 1998
Shigenori Murata; Nobuyoshi Takasaki; Toshio Okazaki; Takanori Kobayashi; Ken-ichi Numachi; Kun-Hsing Chang; Norihiro Okada
動物遺伝育種研究 = The journal of animal genetics | 2002
Hideyuki Imai; Ken-ichi Numachi