• International Journal of Industrial Entomology and Biomaterials
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• v.5 no.1
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• pp.1-12
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• 2002

Ecophysiologically diapause represents a syndrome of physiological and biochemical characteristics, all of which ensure survival during a long period of dormancy. Since, silkworm enters diapause as embryo at the early embryonic stage, the duration of egg life depends on the duration of embryonic diapause. The nature of diapause in silkworm, Bombyx mori, is primarily determined by genetic characters and endocrinologicnl mechanisms, mediated by environmental factors such as temperature and photoperiod. Hibernating potency value besides nucleic acid and carbohydrate metabolism, production and utilization of sorbitol are also equally responsible for induction, initiation, determination, maintenance and termination of diapause. Embryonic diapause in Bombyx moir, induced by active secretion of sub-oesophageal ganglion is attributed to hormonal system and metabolic adjustment, which serves to bring about a new physiological state. Metabolic conversion of trehalose to glycogen at induction, glycogen to sorbitol at initiation and sorbitol to glycogen at termination of diapause is correlated and in each metabolic shift a key enzyme becomes active in response to hormonal and environmental stimulation. An attempt has been made in this review article to discuss briefly the nature of embryonic diapause, influence of various factors on diapause nature, hormonal mechanism of diapause besides biochemical composition of egg, nucleic acid and carbohydrate metabolism, production and utilization of sorbitol in relation to induction, determination, maintenance, initiation and termination of diapause in the silkworm, Bombyx mori.

• BMB Reports
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• v.41 no.5
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• pp.394-399
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• 2008

Multiple sequence alignments of the Bombyx mori fibroin light chain gene (fib-L) from hybrids and from Chinese and Japanese strains demonstrated that 51.6% of the fib-L third intron is conserved. One of these conserved segments, 41 bp long, contains the sequence CGTTATTATACATATT, which is duplicated in the B. mori Nd-$s^D$ mutant. In the present work, electrophoretic mobility assays and computational analyses revealed a major peak of intrinsic bent DNA within the segment that undergoes breakage in the previously-described Nd-$s^D$ mutation. This result suggested that this intrinsically-curved region might mediate DNA cleavage and enhance recombination events in the third intron of the Bombyx mori fib-L gene.

• International Journal of Industrial Entomology and Biomaterials
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• v.29 no.2
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• pp.145-152
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• 2014

The variation in the level of immune response related gene expression in silkworm, Bombyx mori following infection with Bombyx mori nucleopolyhedrovirus (BmNPV) was analyzed at different time intervals. The occlusion bodies of BmNPV orally inoculated to the two most divergent silkworm races viz., Sarupat (resistant to BmNPV infection) and CSR2 (susceptible to BmNPV infection) were subjected to oral BmNPV inoculation. The expression profile of gp 41 gene of BmNPV in the Sarupat and CSR2 races revealed that the virus could invade the midguts of both susceptible and resistant races. However, its multiplication was significantly less in the midgut of resistant race, while, in the susceptible race, the viral multiplication reached maximum level within 12 h. These findings indicate that potential host genes are involved in the inhibition of viral multiplication within larval midgut. The immune response genes arylphorin, cathepsin B, gloverin, lebocin, serpin, Hsp 19.9, Hsp 20.1, Hsp 20.4, Hsp 20.8, Hsp 21.4, Hsp 23.7, Hsp 40, Hsp 70, Hsp90 revealed differential level of expression on NPV infection. The gloverin, serpin, Hsp 23.7 and Hsp 40 genes are significantly up-regulated in the resistant race after NPV infection. The early up-regulation of these genes suggests that these genes could play an important role in baculovirus resistance in the silkworm, B. mori.

• Journal of Sericultural and Entomological Science
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• v.40 no.1
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• pp.60-62
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• 1998

To understand expression of some early and late genes of Bombyx mori nuclear polyhedrosis virus (BmNPV) in the B. mori-derived BmN cell line, the transcripts were analyzed by polymerase chain reaction with synthetic primers. After infection, the transcript of early genes, which include p35, IE1 and helicase p143, was immediately detected in the infected cells. In addition, the transcript of late genes, which include p10 and polyhedrin, was also detected in just-infected cells. In conclusion, our results revealed that transcripts of early and late genes of BmNPV are immediately expressed from the cells after infection.

• International Journal of Industrial Entomology and Biomaterials
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• v.10 no.2
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• pp.87-94
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• 2005

Mating is an essential behavioural social event in the life cycle of silkworm, Bombyx mori (L.) for the perpetuation of population. A number of intrinsic and extrinsic factors and events of significant importance are involved in successful mating and egg deposition by an adult silk moth which besides biochemical, physiological and environmental factors also includes attraction of reproductively competent male and female moth for mating, duration and frequency of mating, age of moth at the time of mating, reuse of male moth in the production of eggs etc. An attempt has been made in this review article to elucidate briefly the behaviour of male towards female moth after eclosion, impact of duration and frequency of mating on egg deposition and oviposition, reuse of mated male moth in the production of quality and quantity eggs etc. in the silk-worm, B. mori and its significance in silkworm seed production.

• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.2
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• pp.231-233
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• 2003

To understand the physical method for induction of anti-bacterial substances from the silkworm larvae, Bombyx mori, three physical methods, i.e., infrared radiation, ultraviolet radiation and ultrasonic wave, have been used in this study. The results have shown that ultrasonic wave can induce anti-bacterial sub-stances effectively than radiations in the B. mori larva. The induction of anti-bacterial substances was different from silkworm race to race. Summer-autumn silkworm race (Qiufeng${\times}$Baiyu) was easy to induce antibacterial substances. It is suggested that the ultrasonic wave is a simple and easy method for induction.

• International Journal of Industrial Entomology and Biomaterials
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• v.12 no.1
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• pp.15-19
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• 2006

RNA interference has been used as a powerful tool in preventing virus proliferation in many species. In this study, we injected the dsRNA in vitro transcripts into Bombyx mori to investigate the resistance to B. mori nuclear polyhedrosis virus (BmNPV). Through vivisectional observation and real-time quantities PCR analysis, we found that these dsRNA can prevent the BmNPV to a certain extent, and delay the viruses' proliferation.

• International Journal of Industrial Entomology and Biomaterials
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• v.1 no.1
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• pp.53-58
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• 2000

A cDNA encoding the luciferase of firefly Luciola lateralis was cloned downstream from the polyhedrin gene promoter of Bombyx mori nucleopolyhedrovirus and expressed in B. mori cells (BmN-4). The coding soquence for luciferase was inserted into pBmKSK2 rectors) which was reconstructed from the polyhedrin-based transfer vector pBmKSKl by modifying cloning sites. Recombinant virus, BmK2-LUCDF, containing the luciferase gene was selected and purified in BmN-4 cells. The emission of luminescence by luciferase was only detected in BmK2-LUCDF-infected cell extracts. This result indicates that the cloned new luciferase gene of firefly L. lateralis can be expressed efficiently in baculovirus expression system and used as a useful reporter gene.

• Journal of Life Science
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• v.8 no.3
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• pp.285-293
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• 1998

We have cloned an internal fragment of the putative transoisase gene of MLE in the silkworm, Bombyx mori, using PCR method with degenerative oligonucleotide primers designed to represent regions of amino acids encoding transposase. The resulting PCR clone, designed as BmoMAR, cords a partial ORF(152 a.a.) of MLE in which interrupted by five stop codons, and the sequence of its deduced amino acids showed 37% homology with Mos1, an active mariner, from Drosophila mauritiana. Furthermore, the BmoMAR exhibits nucleotide and amino acid homology with 59% and 37% from Apis mellifera and D. mauritiana 7.9 clone, respectively. This result strongly that a MLE is present in the genome of B. mori.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.1
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• pp.93-97
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• 2003

We describe here the cloning of a cDNA encoding putative calreticulin (CRT) from the silkworm, Bombyx mori. The CRT cDNA comprised of 1,194 bp encoding 398 amino acid residues. B. mori. CRT has a HDEL sequence at the end of the C-domain. The B. morl, CRT showed 88% protein sequence identity to the G. mellonella CRT, 71 % to A. aegypti CRT, and 63% to H. sapiens CRT, Phylogenetic analysis revealed that the deduced amino acid sequences of the B. mori CRT formed a highly inclusive subgroup with other insect CRTs. Northern blot analysis exhibited an expression of the B. mori CRT gene in the fat body, evidencing the fat body as a major site for CRT synthesis.