• Journal of Sericultural and Entomological Science
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• v.30 no.1
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• pp.25-32
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• 1988

In order to examine a physiological role of juvenile(JH) binding proteins in the hemolymph of the silkworm larva, Bombyx mori, [3H] JH I incubated hemolymph was separated by polyacrylamide gel electrophoresis in the fifth-instar larva and the activity of the binding protein was analyzed using charcoal binding assay. The results obtained were as follows; 1. The JH was bound by two protein fractions in the hemolymph of the fifth-instar larva; One was JH binding lipoprotein(JH-LP), the other was JH speific binding protein(JHBP). Their relative mobility values(Rm) were 0.3∼0.33 and 0.81∼0.84, respectively. There were no valid differences in those values from developmental stages of both male and female silkworms. 2. Total protein contents of the hemolymph were gradually increased during the fifth-instar larva, while at the prepupa decreased. The maximum ones were observed at the spinning period and the contents from female were much higher than those from the male. 3. JH binding activity per ml of the hemolymph was low in the early stage of the fifth-instar larva and its activity was maximized at the psinning period and at the prepupa slightly decreased. 4. There was a similar pattern between changes of the JH binding activity per ml of the hemolymph and of the total protein contents of the hemolymph. 5. The JH binding activity per mg of the hemolymph proteins was high in the early stage of the fifth-instar larva, while from the 6th day of the fifth-instar larva to the prepupa its activity showed the lowest levels.

• Journal of Sericultural and Entomological Science
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• v.39 no.2
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• pp.161-168
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• 1997

To clarify the effect of anti-juvenile hormone analogue (AJH) on the larval ecdysis by feeding at early stage of the 4th instar, the total amount of protein and activity of chitinolytic enzymes in the integument of Bombyx mori were analyzed, PAGE pattern of the protein was observed and the morphological changes of integument during molting period were also observed and the morphological changes of integument during molting period were also observed by means of TEM. The total amount of protein was greatly increased in premolting, then reached maximum level just before ecdysis, and rapidly decreased after the larval ecdysis in the control, while in the AJH treatment, increased 12 hr later than the control and its maximum was only 82.6% of the control. Two specific proteins, which were presumed as the protein originated from endocuticle, also appeared 12 hr later than the control and were maintained to 132 hr after AJH treatment from the aspects of the Native- and SDS-PAGE patterns, although those of the control disappeared instantly after ecdysis. Chitinase and $\beta$-N-acetylglucosaminidase activities were also suppressed and delayed by AJH treatment. Furthermore, it was observed that the apolysis took place 12 hr later than the control but new epicuticle was not formed at least until 132 hr after AJH treatment. From these results, it is suggested that the larval molting process of silkworm develops 12 hr later than the control but new epicuticle was not formed at least until 132 hr after AJH treatment. From these results, it is suggested that the larval molting process of silkworm develops 12 hr later than the control by AJH treatment but no further processing takes place just after apolysis.

• Journal of Sericultural and Entomological Science
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• v.37 no.2
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• pp.114-120
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• 1995

The effect of juvenile hormone analogue(JHA, Manina) on larval feeding duration, pupation ratio, cocoon weight, and cocoon shell weight in the present commercial parent and hybrid silkworm stocks were investigated. Topical applications of JHA on parent silkworm stocks were to prolong larval duration, but results of response on those stocks were not consistent. Especially the JHA on Jam 121, Jam 123 and Jam 138 did not play a role in larval duration, whereas that on Jam 114 was most effective in prolongation more than two days, compared with the controls. subsequent prolongation of feeding duration resulted in increase of cocoon weight and cocoon shell weight of most parent silkworm stocks, while Jam 114 showed decrease in cocoon weight and cocoon shell weight in spite of prolonged feeding duration of two days. Unlike the parent silkworm stocks, durations of feeding period in all hybrid silkworm stocks were prolonged about one day. Treatments of JHA on the hybrid stocks gave rise to increase of cocoon weight and cocoon shell weight, and especially were most effective in Sasung-jam, Eunbaek-jam and Samgwang-jam. Although treatments of JHA seemed to have no harmful effect on physiology of parent silkworm stocks as well as that of hybrid stocks, the JHA retarded pupation ratio of some parent silkworm stocks such as Jam 122, 131, 135 and 138 by about 10%.

• Journal of Sericultural and Entomological Science
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• v.32 no.1
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• pp.31-37
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• 1990

For fine-denier cocoon filament production, the precocious trimolting silkworms were induced by the treatments with both the imidazole compound "KK-42" hating anti-juvenile hormone activity and high temperature, and their growth, dietary efficiency, cocoon and cocoon filament qualities were compared with those of normal tetramolters as control. 1. The percentage of precocious trimolters was higher in the application of KK-42 than the treatment of high temperature. The effective concentration of KK-42 was 10$\mu\textrm{g}$/1arva. The high temperature treatment for 48 hour was more effective than 36 hour treatment, and silkworm larvae fed on mulberry leaves were more sensitive than artificial diet to induce trimolters. 2. The larval duration of the trimolters induced by KK-42 was 5.17 day shorter than that of normal tetramolters in mulberry leaves rearing, and the increasing pattern of body weight in the 4th inster larvae of trimotlers was similar to the 5th instar larvae of normal tetramolters. 3. The qualities such as cocoon weight, cocoon layer weight and cocoon layer ratio of precocious trimolter induced by KK-42 were much lower those of normal tetramolters: the cocoon weight and cocoon layer ratio were 0.78g, 14.2cg and 18.4% in mulberry leaves rearing, and 0.86 cg, 10.3cg and 12.3% in artificial diet rearing, respectively. 4. The size of cocoon and cocoon filament was smaller in the precocious trimolter, both KK-42 and high temperature, as compared with that of the normal tetramolters. 5. The efficiency of cocoon layer production of the precocious trimolters by the KK-42 was lower than that of the normal tetramolters: amount of the cocoon layer production per 1g of dry mulberry leaves ingested was 7.97cg in the precocious trimotors, while 9.20cg in the normal tetramolters.