Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||National Institute of Genetics|
IMAI Hirotami T. National Institute of Genetics Associate Professor, 細胞遺伝研究系, 助教授 (10000241)
CROZIER R.H La Trobe Univ., 遺伝部門(オーストラリア), 教授
TAYLOR Robert W. CSIRO,Dept.of Entomology, Australia, 昆虫部門(オーストラリア キャンベラ), 名誉研究員
OGATA Kazuo Institute of Tropical Agriculture, Kyushu University, 熱帯農学研究センター, 助手 (40224092)
HIRAI Hirohisa Primate Research Institute, Kyoto University, 進化系統部門, 助手 (10128308)
YAMAMOTO Masa-Toshi Kyoto Institute of Technology, 繊維学部, 助教授 (10142001)
CROZIER Ross H. La Trobe University, Australia
高畑 尚之 総合研究大学院大学, 教授 (30124217)
CROZIER R.H. オーストラリア La Trobe Univ., 遺伝部門, 教授
|Project Period (FY)
1994 – 1995
Completed(Fiscal Year 1995)
|Budget Amount *help
¥9,100,000 (Direct Cost : ¥9,100,000)
Fiscal Year 1995 : ¥4,500,000 (Direct Cost : ¥4,500,000)
Fiscal Year 1994 : ¥4,600,000 (Direct Cost : ¥4,600,000)
|Keywords||Chromosome evolution / Ants / Minimum interaction theory / Phyletic evolution / FISH method / rDNA / Telomere / Mitochondria / 昆虫|
This field research program was performed in 1995 and 1996 to obtain experimental evidence for the minimum interaction theory of animal karyotype evolution (Imai et al., 1986) by using chromosomally divergent (2n=2-84) Australian ants of the genus Myrmecia.We revealed following points :
(1) Karyotype evolution of Myrmecia proceeds in terms of the karyograph analysis toward increasing chromosome number by centric fission (2n=2-4*2n=84).
(2) The termini of Myrmecia chromosomes were sealed by (TTAGG)n type telomeres, which were not detected in interstitial sites.De novo formation telomeres by telomerase was suggested.
(3) A unique phenomenon termed "rDNA-dispersion" was observed, by which the number of chromosomes carrying 28S rDNA increases from 2 in species with low chromosome numbers (2n=2-10) to 8-19 in species with high chromosome numbers (2n=38-76).Centric fission and a reciprocal translocation occurring in C-bands were detected as major mechanisms involved in rDNA-dispersion.
These results are highly consistent with the minimum interaction theory.