Male Silkworm Research Articles

Tissue distribution, developmental changes and some catalytic properties of guanosine 3',5'-monophosphate-dependent protein kinase of Bombyx mori.

The levels of guanosine 3′,5′-monophosphate (cGMP)-dependent protein kinase in the larval and pupal tissues of Bombyx mori were estimated. This activity was highest in the fat body of the female pupa. The enzyme showed a significant variation in activity during development of adult in female. Male silkworm gave less significant results. The cGMP-dependent kinase partially purified from the pupa could be activated by a high concentration of adenosine 3′,5′-monophosphate (cAMP) as reported for cGMP-dependent protein kinases from other sources. The nature of the enzyme thus activated and that of the enzyme activated by a low concentration of cGMP were found to be similar in several aspects. This indicates that the intrinsic activity of protein kinase from the silkworm pupa is independent of the kind of cyclic nucleotide as an activator.

The chemistry of the silkworm diapause hormone. V. Diapause hormone B: Its selective extraction and isolation from the silkworm, Bombyx mori.

A selective extraction procedure of the diapause hormone-B (DH-B) from male silkworm adult heads is described. By this new method a highly active extract (1 DH unit in 30_??_60μg) can be obtained easily without chromatographic purification. It was further purified by successive gel permeation chromatographies to give finally pure DH-B having an activity of 1 DH unit in 2 μg.

The Neural Control of Spermatophore Formation and Sperm Transfer in the Silkworm, Bombyx mori L.

The removal of the head of the male silkworm, Bombyx mori L., immediately after mating commences does not alter the production of fertile eggs by the female. The brain and suboesophageal ganglion are not required for spermatophore formation and sperm transfer. When the nerve cord is cut between the 2nd and 3rd abdominal ganglia 1–2 min after mating it significantly reduces egg production and egg fertility. It is possible that the passage of the accessory fluids is under partial control of ganglia anterior to the 3rd abdominal ganglion but not the brain or suboesophageal ganglion, and the amount transferred to the females may affect the number of eggs laid and the fertility of the eggs.

Embryonic Death in Progeny of Male Silkworms Treated with Apholate : Difference in Treatment at Different Stages, and in Temperatures after Treatment : Lepidoptera : Bombycidae

Embryonic Death in Progeny of Male Silkworms Treated with Apholate : Difference in Treatment at Different Stages, and in Temperatures after Treatment : Lepidoptera : Bombycidae

The spindle as a basal body distributor. A study in the meiosis of the male silkworm moth, Bombyx mori.

ABSTRACT The spindle of metazoan cells functions as a dual distributor that guarantees the accurate segregation of both chromosomes and centnoles (basal bodies). This combined mechanism may have evolved from the separate distribution devices for chromosomes and basal bodies found in Protozoa. Typical eupyrene spermatocytes of the silk moth were compared with atypical apyrene spermatocytes. (a) Long microtubules, persisting during centnolar movements, develop in the meiotic prophases in continuity with the centrtoles (b) There is no longer a centriole-microtubule continuity at metaphase-anaphase (c) Spindles comprise microtubules and endoplasmic reticulum (ER). The microtubules form a barrel-shaped structure terminating far in front of the centrioles. The two types of spermatocytes differ in the structure of the ER, which is vesicular in the eupyrene and lamellar in the apyrene line. It is suggested that the ER influences the anaphase movement of chromosomes, (d) The chromosomes lack localized centromeres. Microtubules penetrate all along the polar faces of the eupyrene metaphase chromosomes. The apyrene chromosomes form irregular blocks that are penetrated by microtubules all around their periphery, (e) The centriole comprises 3 concentric zones. Typical changes in the centnole are correlated with changes in the cell cycle. Replication, de novo formation and disappearance of centrioles are manifestations of the state of flux of the microtubules.

Frequency pattern of mosaic and whole-body mutants induced by ionizing radiations in post-meiotic cells of the male silkworm

This paper is concerned with mutation spectra induced by γ- or X-rays in postmeiotic germ cells of male silkworm with special regard to the change in frequency pattern of mosaic (fractional) and whole-body (complete) mutants. When silkworm spermatozoa are irradiated with γ-rays, the frequency of whole-body mutants increases linearly with increasing dose, whereas that of mosaics increases exponentially. The latter relation is in striking contrast to that observed in Drosophila, where the incidence of mosaics has been known to reach a plateau at a relatively low dose level. Several possibilities are considered for the interpretation of the difference. Mosaics produced after irradiation of silkworm spermatozoa appear to form a mixed class of at least two types, single-helix type and chromosome-aberration type. The proportion of both may vary depending on the irradiated dose. The incidence of mosaics in comparison to that of whole-body mutants varies considerably with the progress of spermatogenesis. On a per R-basis, spermatogonia yield the lowest frequency of mosaics; the frequencies of both complete and mosaic mutations increase sharply through meiotic prophase up to V-4.5 (fifth instar larvae, day 4.5). Until this stage relatively more completes than fractionals are produced. Around V-4.5 the ratio of mosaics to completes reaches unity. From this stage onward, during spermiogenesis, relatively more mosaics than completes are produced, although their absolute frequencies of induction are far lower than in V-4.5. This observation may be interpreted as resulting from a greater capacity for repair of premutational damage leading to mosaic mutations in the early than in the late stages of spermiogenesis.

Sterilizing Effect of High Temperature on the Male Silkworm, Bombyx mori L. : Lepidoptera : Bombycidae

Sterility of the male silkworm, Bombyx mori induced by high temperature (32°C)was investigated in relation to their developmental stages. The sterilizing effect of high temperature was the strongest at the prepupal stage, from spining to pupation, and followed by the pupal period, whereas no sterilizing effect was obtained in the fifth larval instar. In the treatment with cyclic changes of high (32°C) and moderate(23°C) temperatures for 8 days from spining to early pupae, no sterilization occurred when the treatment was given at 12 hr intervals, but the starility markedly increased if the time intervals were extended to 24 hr. Furthermore, a relationship between male sterilization and developmental stages of the insect was discussed, paying a particular consideration on the development of their germ cells.

Embryonic Mortality in the Progeny of the Male Silkworm, Bombyx mori L., Orally Administered Apholate in the Larval Stage (Lepidoptera : Bombycidae)

Embryonic Mortality in the Progeny of the Male Silkworm, Bombyx mori L., Orally Administered Apholate in the Larval Stage (Lepidoptera : Bombycidae)

Comparative studies of mutation frequencies induced by 32P treatment and γ-irradiation in the male silkworm

The frequency of mutation induced in the male silkworm fed with 32P on the third day of the fourth instar (shortly before meiosis) was compared with that induced by γ-irradiation. The daily dose of γ-rays was careflly adjusted day by day so as to fit the daily change in the absorbed dose delivered to the gonad by the ingested 32P. The gonad dose for the 32P treated group was estimated by applying Loevinger's equation; the parameters involved in the equation were experimentally determined with special care for biological factors. Using the 32P dose estimates thus determined, we found that the mutation frequency was equal for the 32P and γ-ray groups at the same absorbed dose. We conclude that there could be no chance for a mutation induced by 32P transmutation to show up under the present conditions and that the proposed 32P dosimetry is satisfactory.

Studies on the Influence of Radioactive-rays upon the Hemocytes of the Silkworm, Bombyx mori, L.

Attempts were made to show some sexual differences in the destructive influences of radiation upon the numbers of hemocytes of the silkworm. Just moulted silkworm larva of the fifth stage were administered 0.1 cc of 0.5% solution Ca/sup 4//sup 5/Cl or 0.3% solution of H/sub 3/P/sup 3//sup 3/O/sub 4/ through the mouth. It was concluded from the results that the largest damage of Ca/sup 4//sup 5/ and P/sup 3//sup 2/ was inflicted on the proleucocyte, especially in the male silkworm. (P.C.H.)