2006 Fiscal Year Final Research Report Summary
Eupyrene-apyrene dimorphic spermatogenesis in Bombyx (Lepidoptera): Significance and differentiation mechanisms.
| Project/Area Number |
15380044
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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 |
Applied entomology
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| Research Institution | Rakuno Gakuen University |
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Principal Investigator |
YAMASHIKI Naoko Rakuno Gakuen University, Faculty of Environmental Systems, Professor, 環境システム学部, 教授 (40112578)
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| Co-Investigator(Kenkyū-buntansha) |
SAHARA Ken Hokkaido University, Graduate School of Agriculture, Assistant, 大学院・農学研究科, 助手 (30241368)
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| Project Period (FY) |
2003 – 2006
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| Keywords | Spermatogenesis / Cell Differentiation / Lepidopteran Insect |
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| Research Abstract |
In males of silkworm Bombyx mori, two types of spermatozoa, nucleate eupyrene and anucleate apyrene, are produced in the same testes, although only the eupyrene fertilize the eggs. We focused on that the transition from eupyrene line to the apyrene line occurred in 1) what stages of silkworm development, and 2) what stages of spermatogenesis. It has revealed that 3) not only both types of sperm but the cyst cells, somatic cells that enclose the sperm bundles, follow the different way of development in the testes and the seminal vesicle. 1. The dimorphic sperm production in vitro cultivation of spermatocysts has been almost established, and what stages of silkworm development the transition from eupyrene line to the apyrene line occurred will be cleared by using the cultivation system. 2. By visualizing the chromosome behavior, microtubule dynamics, distribution of y-tubulin (one of the components in microtubule organizing center), any indications of the eupyrene-apyrene line differentiation were not found in the spermatogonia. In the primary spermatocytes, the different fate to eupyrene or apyrene first became evident by the fact that the homologous chromosomes to form the bivalents in eupyrene line and not in apyrene line. Any of molecular candidates were not identified yet in Bombyx. 3. In a layer of cyst cells, differences of histochemical characteristics and submicroscopic structures were detected between the eupyrene and apyrene bundles. After the lysis of cyst cells before they left the testis, apyrene bundles were disrupted while the eupyrene maintained the bundle form. Our findings may indicate that the cyst cells secrete a certain substance to maintain the bundle form of the eupyrene. The invidualized apyrene is considered to play important role in assisting eupyrene bundle during their passage through the male and female genital tracts
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