• International Journal of Industrial Entomology and Biomaterials
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• v.15 no.1
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• pp.1-7
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• 2007

At present, multivoltine silkworm races reared five times per year involving huge manpower and rearing expenditure. Egg diapausing behavior is facultative in multivoltine and egg diapause was induced in selected multivoltine races by regulating temperature at $18^{\circ}C$, relative humidity 80% and photoperiod (6L:18D) in the late stage silkworm rearing. The maximum percentage of egg diapause induction was recorded in Rong Diazo, Diazo and MW13 showed 94%, 93% and 92% respectively, whereas the races A14DY and OS-616 showed minimum diapause induction 15% and 18% respectively. The diapause induced multivoltine eggs were preserved up to six months by cold preservation schedule normally adopted for bivoltine. After three and six months egg preservation, the diapause induced layings were released and observed for hatching percentage, all races showed above 82 % of hatching except the race AP12, which showed only 78 % of hatching. This methods reduce the crop cycle, gives strong safety backup and preventing the genetic erosion. This study helps formulating a new conservation method for multivoltine silkworm germplasm.

• International Journal of Industrial Entomology and Biomaterials
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• v.15 no.2
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• pp.165-169
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• 2007

A differential specific pattern of variation in the metabolism of protein and cholesterol was noticed in non -diapause and diapause eggs due to the significant differences in embryonic development. The rate of metabolism was different due to specific demands of such metabolites during active embryogenesis and maintenance of diapause respectively. In general, the metabolic rate was found to be accelerated in non- diapause eggs just after egg deposition, while it was very slow in diapause eggs. When the diapause eggs were treated with hydrochloric acid within 16-20 hrs, the rate of turnover was found to very similar to non- diapause eggs, though the base level of protein and cholesterol was recorded to be different.

• 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.

• Journal of Sericultural and Entomological Science
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• v.16 no.2
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• pp.111-117
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• 1974

The electron micrographs of the larval brain of the silkworm. Bembyx mori. show that median neurosecretory cell of diapause-egg producer may participate in the production of lipo-granules and that of non-diapause egg producer may do in the production of electron-translucent vesicles. It was found that ribosome-like particles of diapause-egg producer gradually developed into highly dense particles and came into line along the smooth-surfaced endoplasmic reticulum. They finally became lipo-granules.

• Journal of Sericultural and Entomological Science
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• v.13 no.2
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• pp.99-107
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• 1971

In the suboesophageal ganglion of Bombyx mori, the diapause regulator producing cells which may give an information to the diapause factor cells were found by means of electron microscopy. The diapause regulator producing cells had larger granules (2000 to 5000 A$^{\circ}$ in diameter) than did the diapause factor cells which were partially surrounded by the formers. Highly electron-dense material of lysosome in the diapause regulator producing cells was observed in the diapause-egg producer but such lysosomes were not in the non-diapause egg-producer. It was found that many cytoplasmic granules fuse with lysosome, and smaller granules come out of lysosomes. Some implications of the diapause factor cell and the diapause regulator producing cell were discussed.

• International Journal of Industrial Entomology and Biomaterials
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• v.26 no.1
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• pp.31-40
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• 2013

Paralytic peptide binding proteins (PP-BP) are 30KP proteins that show similarity to ENF binding proteins. The ENF-BP act as active regulators of ENF peptides. ENF peptides are multifunctional insect cytokines. The comparison of gene expression in diapause induced and non-diapause eggs at different time intervals after oviposition showed an upregulation of PP at 18h as well as PP-BP at 12 and 18h after oviposition along with few other genes. The current study has been taken up to investigate the role of PP as well as PP-BP in diapause induction in polyvoltine silkworms and to study the multigene organization of PP-BP in the Bombyx mori genome. The tissue specific expression analysis revealed that, PP-BP is highly expressed in fat body followed by egg and brain while no expression was observed in midgut. The expression levels of PP and PP-BP in diapause and non-diapause eggs from 0h to 48h after oviposition, validated through realtime PCR revealed that PP is highly expressed at 18 and 24h while PP-BP expression is higher at 12 and 18h time intervals suggesting their possible role in diapause induction. The whole genome survey of the PP-BP paralogous sequences revealed a total of 46 B. mori PP-BP homologs that are classified into 3 categories viz., ENF-BP, Typical 30KPs and serine/threonine rich 30KPs. These paralogous sequences are distributed on chromosomes 7, 20, 22 and 24, all 30KP and S/T rich 30KP proteins are present in the same locus of chromosome 20.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 1997.06a
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• pp.51-72
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• 1997

Diapause hormone (DH) is a neuropeptide hormone which is secreted from the suboesophageal ganglion (SG) and is responsible for induction of embryonic diapause of the silkworm, Bombyx mori. DH is isolated from SGs and determined to be a 24 amino acid peptide amide. The cDNA encodes the polyprotein precursor from which DH, pheromone biosynthesis activating neuropeptide (PBAN) and three other neuropeptides are released and become matured. The C-terminal FXPRL-NH2 sequence of DH is essential but not sufficient for expression of full activity. Recently, we have isolated a unique hydrohobic peptide (VAP peptide) with a slight diapause egg induceing activity from organic solvent extracts of the male adult heads of the silkworm. The VAP peptide itself has no diapause inducing activity, but enhances DH activity through reducing ED50 value and the threshold concentration of DH. The DH-PBAN gene is composed of 6 exons interrupted by 5 introns and is expressed in 12 neurosecretory cells of the SG. The incubation of eggs at 25$^{\circ}C$, which induces embryonic diapause in the progeny, caused DH-PBAN mRNA content to increase at 5 different stages in the life cycle. By contrast, a 15$^{\circ}C$ incubation only induced expression of the gene at the late phrase adult stage. The temperature-controlled expression of DH-PBAN gene is closely correlated to the incidence of diapause, indicating that DH-PBAN gene expression is the initial event leading to diapause induction. DH acts to stimulate trehalase activity in developing ovary to bring about hyprglycogenism in mature eggs, a prerequisite metabolism for diapause initiation. Using in vivo and in vitro systems, DH is clearly shown to induce trehalase gene expression in developing ovaries. New protein synthesis is not needed for this process, but a Ca2+-dependent proteinkinase seems to be involved. Quite recently, we have sucessfully applied a new and potent trehalase inhibitor (Trehazoline) to reudce glycogen content in developing ovaries. The eggs deficient in glycogen were also able to enter diapause as the natural eggs do, so that we could provide the new egg system to reconsider the diapause associated metabolism other than the glycogen-sorbitol metabolic system.

• International Journal of Industrial Entomology and Biomaterials
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• v.23 no.2
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• pp.207-213
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• 2011

The diapause of $Telegryllus$ $emma$, the Emma field cricket, was investigated to study the ecological characteristics of the species. Changes in the volume, oxygen consumption, and water content of T. emma eggs were followed from oviposition. An increase in volume, oxygen consumption and water uptake occurred from 7 to 8 days following oviposition. The oxygen consumption of the eggs increased slowly for 7 days following oviposition, but then decreased until 15 days following oviposition. These results showed that a physiological change at diapause initiation affected the volume, water content, and oxygen consumption of the $T.$ $emma$ eggs. An experimental investigation of egg hatching showed that the eggs could be stocked at $10^{\circ}C$ for 40 days with a 14 day pre-period after laying and yield, 62.1% hatchability under these conditions. Maintaining the temperature at approximately $10^{\circ}C$ was favorable for hatching. Another experiment on egg hatching showed that the storage of eggs at $10^{\circ}C$ from 40 to 180 days would ensure satisfactory, hatching capacity.

• Journal of Sericultural and Entomological Science
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• v.15 no.2
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• pp.1-7
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• 1973

It was found that the diapause in the silkworm egg is induced by the action of the diapause hormone secreted from the suboesophageal ganglion, and "esterase A" affects protein metabolism in oocyte and egg. In this connection, some changes in protein metabolism of silkworm egg according to embryonic developments could give some information on the diapause, using Ouchterlony Test. Antigenicity of the protein of silkworm egg was detected through antigen-antibody interaction among the extracts of rabbit blood. Furthermore, existence of the specific antigen was also detected according to embryonic development, using the adsorption test. The results were obtained as follows: 1 Detection of antigenicity The antigenicity of silkworm egg was ascertained by inoculating it into a rabbit, but positive results were shown in most of the silkworm eggs tested, whereas the antibody specific to a certain antigen was not detected. 2. Detection of the common antigen It was demonstrated that most of the antigen could incite the common antibodies, but the specific antibody formation was not detected in a few antigens, even though the nonspecific antibody formation was displayed. 3. Detection of the specific antigen It is suggested that there are the specific antigens detectable in each treated eggs by the adsorption test.

• International Journal of Industrial Entomology and Biomaterials
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• v.16 no.2
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• pp.37-48
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• 2008

The diapause and non diapause associated proteins of multivoltine silkworm eggs were analysed by two dimensional (2D) gel electrophoresis. The study was made at 0 hr, 24 hrs and 48 hrs after oviposition. A total of four protein spots in diapause eggs at 24 hrs of oviposition and two protein spots in non diapause eggs at 0 hrs of oviposition were observed. All the six protein spots were considered to have association with diapause and non diapause characters. The molecular weight (MW) and isoelectric point (PI) of these 6 protein spots were calculated. The protein spots 1 and 2 observed in 0 hr of non diapause eggs were found to have the MW of 67 and 75 KDa and PI of 8.6 and 8.4 respectively. Similarly the four protein spots observed in diapause egg at 24 hrs of oviposition exhibited MW viz., 15, 17,20 and 25 KDa and PI of 5.3, 5.8, 6.5 and 6.0 respectively. All these 6 identified protein spots were subjected to in-gel digestion and resulted tryptic peptides were analyzed by Matrix-assisted laser desorption/ionization time-of flight mass spectrometry (MALDI TOF-MS). Databases searched based on experimentally determined molecular weights of peptides for the determination of the identities of proteins. The identified proteins indicated homology of 34% to 95%. The results indicate that the proteins may playa role in development of diapause and non diapause eggs.