Significance of peristaltic squeezing of sperm bundles in the silkworm, Bombyx mori: elimination of irregular eupyrene sperm nuclei of the triploid

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概要

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• Silkworm (Lepidoptera) males produce dimorphic sperm: nucleate eupyrene sperm and anucleate apyrene sperm. The eupyrene sperm are ordinary sperm to fertilise the eggs, while the function of apyrene sperm remains uncertain. After meiosis, 256 sperm cells are enclosed by a layer of cyst cells, forming a sperm bundle. We have previously documented that the nucleus of eupyrene sperm anchors to the head cyst cell, which locates at the anterior apex of the bundle, by an acrosome tubule-basal body assembly. Neither the basal body attachment to the nucleus nor the acrosome is seen in apyrene sperm, and the nuclei remain in the middle region of the bundle. Peristaltic squeezing starts from the anterior of the bundles in both types of sperm, and cytoplasmic debris of the eupyrene sperm, and both the nuclei and debris of apyrene sperm, are eliminated at the final stage of spermatogenesis. Since the irregularity of meiotic division in apyrene sperm is known, we used triploid silkworm males that show irregular meiotic division even in eupyrene spermatocytes and are highly sterile. The irregular nuclei of the triploid are discarded by the peristaltic squeezing just as those of the apyrene sperm. Transmission electron microscopic observations disclose the abnormality in the acrosome tubule and in the connection to the basal body. The peristaltic squeezing of sperm bundles in the silkworm appears to be the final control mechanism to eliminate irregular nuclei before they enter female reproductive organs.

• Cambridge University Pressの論文

著者

• Sahara K

  Department Of Applied Bioscience Graduate School Of Agriculture Hokkaido University

• Kawamura N

  Biology Laboratory Rakuno Gakuen University

• Yamashiki N

  Biology Laboratory Rakuno Gakuen University

• Kawamura Naoko

  Biology Laboratory, Rakuno Gakuen University

関連論文

• WHY STERILE TETRAPLOID MALE SILKWORMS GAIN FERTILITY BY A STARVE SHOCK?(Developmental Biology,Abstracts of papers presented at the 75^ Annual Meeting of the Zoological Society of Japan)
• PRODUCTION OF APYRENE SPERM BUNDLES IN IN VITRO CULTIVATION OF THE SILKWORM SPERMATOCYSTS(Developmental Biology,Abstracts of papers presented at the 75^ Annual Meeting of the Zoological Society of Japan)
• ROLES OF ACTIN NETWORKS IN PERISTALTIC SQUEEZING DURING SPERM MATURATION IN BOMBYX MORI(Developmental Biology)(Proceedings of the Seventy-Third Annual Meeting of the Zoological Society of Japan)
• REMARKABLE IMPROVEMENT BY DOUBLE COPULATION OF A FEMALE WITH STERILE DIPLOID AND POLYPLOID MALES IN THE SILKWORM(Developmental Biology)(Proceeding of the Seventy-Third Annual Meeting of the Zoological Society of Japan)
• Significance of peristaltic squeezing of sperm bundles in the silkworm, Bombyx mori: elimination of irregular eupyrene sperm nuclei of the triploid
• Behavior of centrioles during meiosis in the male silkworm, Bombyx mori (Lepidoptera)

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