| Project/Area Number |
01580042
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Laboratory animal science
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| Research Institution | The Research Institute of Environmental Medicine, Nagoya University |
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Principal Investigator |
ODA Senーichi The Research Institute of Environmental Medicine, Nagoya University, Assistant Professor, 環境医学研究所, 助手 (60023660)
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| Co-Investigator(Kenkyū-buntansha) |
NAMIKAWA Takao School of Agriculture, Nagoya University, Associate Professor, 農学部, 助教授 (70111838)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1990: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1989: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Suncus murinus / Chromosome / Robertsonean fusion / Development of line / Laboratory animal / Insectivore / 異数染色体 |
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| Research Abstract |
The results of chromosomal analysis in this study indicate that the laboratory shrew lines can be divided into two types on the basis of chromosome number : the 2N=30 type and the 2N=40 type, representing the smallest and largest respectively, of numbers of chromosomes reported in this species thus far. The 2N=30 type is only found in the SRI line originating from a wild population on the west coast of Sri Lanka. However, the wild shrews caught on the east coast of Sri Lanka have been reported to have 2N=32. These facts provide evidence of chromosomal polymorphism within the wild population of shrews in Sri Lanka. On the other hand, the 2N=40 type is composed of the NAGand OKI lines originating from wild populations in Japan as well as the BAN line from Bangladesh. Matings between SRI (2N=30) and Japanese (2N=40) shrews demonstrated that their Fl, F2 and reciprocal backcross progeny were readily produced. The following chromosome numbers were observed in the hybrids : 2N=35 in Fl shrews, 2N=33 to 2N=38 in F2 shrews and 2N=30 to 2N=38 in reciprocal backcrosses. All the hybrids had the same total of 48 autosomearms. Those Robertsonean lines were developed from them. 9 pairs of metacentric chromosomes, one pair of submetacentric chromosomes and 4 pairs of small acrocentric chromosomes. Furthermore, the metacentric chromosomes could be easily subdivided in to 2 groups : 5 pairsof large metacentric chromosomes and 4 pairs of small metacentric chromosomes. The large metacentric chromosomes which were not found in the 2N=40 type, are believed to have been formed via Robertsonean fusions among 10 pairs of large acrocentric chromosomes seen in the 2N=40 karyotype. We believe that the SRI shrew, as well as the Robertsonean fusion strain mouse, is a useful laboratory animal for chromosome studies.
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