Delayed appearance of sperm cells by treatment with juvenile hormone and ecdysteroid on recessive trimolter of Bombyx mori
1997
He, L. (Shinshu Univ., Ueda, Nagano (Japan). Faculty of Textile Science) | Nakagaki, M. | Kajiura, Z. | Takei, R.
The purpose of the present study was to investigate the effects of endocrine treatment on the timing of the appearance of sperm cells in recessive trimolter silkworms. The timing was determined by the onset of formation of the haploid cells (1 C cells), using DNA flow cytometry. The treatments with juvenile hormones and KK-42 (1-benzyl-5-[(E)-2,6-dimethyl-1,5-heptadienyl] imidazole) were conducted at low doses that did not affect the number of larval molt. In the testis of untreated recessive trimolters, 1C cells were formed an day 4 of 4th instar. Treatment with juvenile hormones caused a delay of 2 days in the onset of formation of 1C cells. In contrast, KK-42 treatment hastened the appearance of 1C cells. The onset of 1C-cell appearance changed from day 4 to day 0 of 4th instar with this treatment. High doses of ecdysteroids which caused the supernumerary (4th) larval molt caused few delays in the onset of formation of 1C cells in recessive trimolters. On the other hand, ecdysteroid treatment of dominant trimolters at the same dose as for recessive trimolters did not cause the supernumerary (4th) larval molt, but delayed the appearance of 1C cells for 1 day. These results suggest that juvenile hormones and ecdysteroids may be involved in a process of change from spermatocyte to sperm cell in recessive trimolters
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