Fluctuations in ecdysteroid titre and development during the early stage of the last larval instar of trimoulter strains of the silkworm, Bombyx mori

1992 ◽  
Vol 38 (8) ◽  
pp. 587-593 ◽  
Author(s):  
Shi-Hong Gu ◽  
Yoshimitsu Iwashita ◽  
Fei-Jann Lin ◽  
Yien-Shing Chow
Keyword(s):  
Bombyx Mori ◽  
Early Stage ◽  
Larval Instar ◽  
Silkworm Bombyx Mori

scholarly journals STUDIES ON THE POSTERIOR SILK GLAND OF THE SILKWORM, BOMBYX MORI

1968 ◽  
Vol 38 (3) ◽  
pp. 574-588 ◽  
Author(s):  
Yutaka Tashiro ◽  
Takashi Morimoto ◽  
Shiro Matsuura ◽  
Sunao Nagata
Keyword(s):  
Bombyx Mori ◽  
Early Stage ◽  
Larval Instar ◽  
Silk Gland ◽  
Exponential Increase ◽  
Wet Weight ◽  
Rough Er ◽  
Electron Microscopical ◽  
Silkworm Bombyx Mori ◽  
Posterior Silk Gland

Growth of the posterior silk gland and biosynthesis of fibroin during the fifth larval instar of the silkworm, Bombyx mori, have been studied. In accordance with the exponential increase in the wet weight of the gland, the amounts of DNA, RNA, protein, and lipids per animal increased rapidly in the early stage of the fifth instar (0–96 hr). Biosynthesis of fibroin, on the contrary, mainly proceeds in the later stage of the fifth instar (120–192 hr). Electron microscopical observations have shown that, in the very early stage (0–12 hr), a number of free ribosomes exist in the cytoplasm. Rough endoplasmic reticulum (ER) with closely spaced cisternae was also observed. Then rough ER starts to proliferate rapidly, and at the same time lamellar ER is rapidly or gradually transformed into vesicular or tubular forms. In the later stage of the fifth instar (120–192 hr), the cytoplasm is mostly filled with tubular or vesicular ER. Golgi vacuoles, free vacuoles (fibroin globules), and mitochondria are also observed. It is concluded that in the early stage of the fifth instar the cellular structures necessary for the biosynthesis of fibroin are rapidly formed, while in the later stage the biosynthesis of fibroin proceeds at a maximum rate and utilizes these structures.

Expression of metabolic enzyme genes and heat-shock protein genes during embryonic development in diapause and non-diapause egg of multivoltine silkworm Bombyx mori

Biologia ◽  
2008 ◽  
Vol 63 (5) ◽  
Author(s):  
Ragunathan Saravanakumar ◽  
Kangayam Ponnuvel ◽  
Syed Qadri
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Bombyx Mori ◽  
Early Stage ◽  
Metabolic Enzyme ◽  
Dehydrogenase Gene ◽  
Heat Shock Protein Genes ◽  
High Level ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Silkworm Bombyx Mori

AbstractThe expression of metabolic enzyme genes and heat-shock protein genes (Hsp) during early embryogenesis in diapause and non-diapause eggs of the silkworm Bombyx mori was quantified by semi-quantitative RT-PCR. The trehalase gene (Tre) was expressed in non-diapause eggs up-to nine days, while in diapause eggs was not up regulated. The glycogen phosphorylase gene (GPase) was expressed in non-diapause eggs, whereas in diapause eggs a high level was observed in early stage, but down regulated in later stage. The phosphofructokinase gene (PFK) and sorbitol dehyrogenase-2 gene (SDH-2) expression was fluctuated in non-diapause eggs, whereas in diapause eggs these were expressed only at early stage and not observed in later stage. The glucose-6-phosphate dehydrogenase gene (G6P-DH) in non-diapause eggs was highly expressed during the differentiation phase and decreased in the organogenesis phase. In contrast to this, expression in diapause eggs was of low level during differentiation phase and of high level observed in the organogenesis phase. In the tissues, PFK and SDH-2 were selectively expressed in cuticle and midgut, whereas Tre expression was high in midgut and ovary of larvae incubated at 15°C. The Hsp (20.4, 20.8, 40, 70, and 90) were expressed in both diapause and non-diapause eggs. Their expression was, however, selective in tissues with Hsp20.4 in midgut and ovary, Hsp40 in head, Hsp70 in cuticle and Hsp90 in ovary and head in high amounts at 15°C. These results suggest that the metabolic enzyme genes studied except Hsp play a major role during embryogenesis of diapause and non-diapause silkworm.

Prothoracicotropic hormone is released five times in the 5th-larval instar of the silkworm, Bombyx mori

1993 ◽  
Vol 39 (1) ◽  
pp. 83-88 ◽  
Author(s):  
Yasuhito Shirai ◽  
Yasuo Aizono ◽  
Teruo Iwasaki ◽  
Akira Yanagida ◽  
Hajime Mori ◽  
...  
Keyword(s):  
Bombyx Mori ◽  
Larval Instar ◽  
Prothoracicotropic Hormone ◽  
Silkworm Bombyx Mori

scholarly journals STUDIES ON THE POSTERIOR SILK GLAND OF THE SILKWORM, BOMBYX MORI

1968 ◽  
Vol 38 (3) ◽  
pp. 604-614 ◽  
Author(s):  
Takashi Morimoto ◽  
Shiro Matsuura ◽  
Sunao Nagata ◽  
Yutaka Tashiro
Keyword(s):  
Bombyx Mori ◽  
Larval Instar ◽  
Silk Gland ◽  
Pronounced Increase ◽  
Molt Stage ◽  
Wet Weight ◽  
Electron Microscopical ◽  
Lamellar Type ◽  
Silkworm Bombyx Mori ◽  
Posterior Silk Gland

The development of the cells in the posterior silk gland of the silkworm, Bombyx mori, during the fourth larval instar has been studied. In the early stages of this instar, the wet weight of the gland and the amounts of RNA, DNA, and protein per animal increase logarithmically until they reach a stationary state at about 72 hr. At around 96 hr of the fourth instar, the larvae enter the molting state, which lasts for about 24 hr until the fourth ecdysis. Towards the end of the molt stage, the growth of the silk gland is resumed. Electron microscopical observation shows that in the early intermolt stage the cytoplasm is filled with free ribosomes and with rough endoplasmic reticulum (ER), first of the lamellar type (0–6 hr) and then of the vesicular or tubular type. The Golgi apparatus also is well developed. At the beginning of the molt stage (90–96 hr), however, most of the ER becomes lamellar in type, concentric lamellar structures being occasionally observed, and the Golgi vacuoles disappear. Autophagosomes and lysosomes increase markedly and the apical portion of the cytoplasm becomes extensively vacuolated; this suggests that the secretory activities are completely depressed, and pronounced degenerative changes appear during the molt stage. Towards the end of the molt stage, large lamellar ER elements are fragmented into smaller lamellae and there is a pronounced increase in the number of free ribosomes.

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