1996 Fiscal Year Final Research Report Summary
Molecular mechanisms of adaptive evolution on duplicated gene families in Drosophila.
| Project/Area Number |
07454205
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
遺伝
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
YAMAZAKI Tuneyuki Kyushu Univ., Dept.of Biol., Professor, 理学部, 教授 (10108649)
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| Co-Investigator(Kenkyū-buntansha) |
NITASAKA Eiji Kyushu Univ., Dept.of Biol., Reseach Associate, 理学部, 助手 (60222189)
TACHIDA Hidenori Kyushu Univ., Dept.of Biol., Associate Professor, 理学部, 助教授 (70216985)
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| Project Period (FY) |
1995 – 1996
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| Keywords | adaptive evolution / amylase / duplicated gene / Drosophila / spacer region / concerted evolution / natural selection |
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| Research Abstract |
Molecular analysis of amylase system revealed that positive natural selection has been operating in various parts of this amylase regions during the evolutinary process as well as among polymorphic isozymes, as shown below : (I) Strong within-species similarity was observed between the duplicated Amy coding region in contrast to the clear among-species similarlity in non-coding region within each locus throughout the species subgroup, suggesting the presence of natural selection during substitution process if there is no difference in the frequency of homogenizing event between different regions. (II) Frequency of amino acid changing substitution was much higher in "equal class"where the same substitution occurred at the same site of both of the duplicated loci in all eight species examined, than "not-equal class" where at least one of the eight species had different substitutions between the two duplicated loci, indicating positive selection at these sites. In addition this tendency w
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as also observed in species specific substitution, again suggesting adaptive species specific substitution. (III) The age of substitution in two different 5' upstream spacer region of amylase coding sequence, each of which was selected on the basis of differentiation between two species, was significantly different. The frequency of the substitution occurred before speciation but after duplication of the loci, and that occurred after speciation were different between regions, indicating the presence of the selective substitution. (IV) Experimental study using P element mediated transformation and transient expression assay of amylase non-coding regions showed that one distal spacer region which diverged between the two loci was indeed functionally important not only for the distal gene, but also for the expression of proximal gene. (V) Both inducibility and the frequency of polymorphic isozymes changed in population cages maintained in two different foods, starch and glucose. All these results clearly show that natural selection is important factor in determining both evolutionary process and frequency dinamics of polymorphic alleles, including spacer region. Less
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