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1996 Fiscal Year Final Research Report Summary

DNAの進化と変異の機構

Research Project

Project/Area Number 07454208
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 遺伝
Research InstitutionNational Institute of Genetics

Principal Investigator

HARADA Tomoko  National Institute of Genetics, Department of Population Genetics, Professor, 集団遺伝研究系, 教授 (80000256)

Co-Investigator(Kenkyū-buntansha) TAJIMA Fumio  University of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (30183065)
TAKANO Toshiyuki  National Institute of Genetics, Department of Population Genetics, Research Asso, 集団遺伝研究系, 助手 (90202150)
Project Period (FY) 1995 – 1996
KeywordsDNA polymorphism / Molecular evolution / Slightly deleterious mutation / Adaptive evolution
Research Abstract

Molecular mechanism of gene evolution has been a fundamental problem in evolutionary biology for many years. One focus of controversy concerns the effect and significance of natural selection. The present study mainly put a focus on dissection of DNA changes into nonsynonymous and synonymous substitutions which occurred among closely related species in mammals and Drosophila. Amino-acid-altering substitution, or nonsynonymous substitution, is naturally considered to be more exposed to natural selection than synonymous change. Thus, the comparison between these two patterens in a gene provides a good opportunity to evaluate the effect of natural selection. Along this line, we studied the pattern of molecular evolution in mammalian and Drosophila genes. Particularly, we could reveal that the ratio of replacement to synonymous changes in the lineage leading to rodent is lower than that in the primate lineage. This is consistent with the nearly neutral mutation model, which advocates that most of amino acid changes are slightly deleterious. The variation in nonsynonymous substitution among lineages was significant in mammals after weighting the lineage effects. The ratio of replacement to synonymous substitutions also varied significantly among lineages for some of the genes studied in Drosophila. This episodic molecular evolution cannot be explained by the epistatic effect among amino acid sites. Thus, fluctuation of population size or selective constraint should be taken into consideration. Otherwise, positive Darwinian evolution may have some impact on molecular evolution. Further study on higher-order interaction will be also needed to understand the molecular evolution of the complicated genetic systems and to dissect the effects of natural selection and random genetic drift.

  • Research Products

    (14 results)

All Other

All Publications (14 results)

  • [Publications] Tomoko Ohta: "Synonymous and nonsynonymous substitutions in mammalian genes and the nearly neutral theory." J.Mol.Evol.40. 56-63 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tomoko Ohta: "Development of neutral and nearly neutral theories." Theoretical Population Biology. 49. 128-142 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Peter Parham: "Population biology of antigen presentation by MHC class I molecules." Science. 272. 67-74 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tomoko Ohta: "Role of random genetic drift in the evolution of interactive systems." J. Mol. Evol.(in press).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Fumio Tajima: "Effect of non-random sampling on the estimation of parameters in population genetics." Genetical Research. 66. 267-276 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Y.Otsuka: "Genetic variation in the expression of the six hsp genes in the presence of heat shock in Drosophila melanogaster." Genes & Genetic Systems. (in press).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Toshiyuki S.Takano: "Current topics on molecular evolution" Inst.of Mol.Evol.Genet.,The Penn. State Univ.,USA,Graduate School for Advanced Studies,Hayama,Japan., 260 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ohta, T.: "Synonymous and nonsynonymous substitutions in mammaliangenes and the nearly neutral theory." J.Mol.Evol.40. 56-63 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Ohta, T.and Gillespie, J.H.: "Development of neutral and nearly neutral theories." Theoretical Population Biology. 49. 128-142 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Parham, P.and Ohta, T.: "Population biology of antigen presentation by MHC class I molecules." Science. 272. 67-74 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Ohta, T.: "Role of random genetic drift in the evolution of interactive systems." J.Mol.Evol.(in press). (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tajima, F.: "1995 Effect of non-random sampling on the estimation of parameters in population genetics." Genet.Res.66. 267-276 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Otsuka, Y., Takano, T.S.and Yamazaki, Y.: "Genetic variation in the expression of the six hsp genes in the presence of heat shock in Drosophila melanogaster." Genes & Genetic Systems. (in press). (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Takano, T.S.: Genetic study of species differences as observed as loss of bristles in interspecific hybrids of Drosophila.In Current topics on molecular evolution, eds.M.Nei and N.Takahata, pp255-260. Institute of Molecular Evolutionary Genetics, The Pennsylvania State University, USA,The Graduate School for Advanced Studies, Hayama, Japan., (1996)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1999-03-09  

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