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

Abstract

The 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 (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.

Characterization of three transcripts encoding small heat shock proteins expressed in the codling moth, Cydia pomonella (Lepidoptera: Tortricidae)

“…Many sHsps exist as oligomers and can have molecular masses up to 800 kDa (MacRae, 2000) with the α‐crystallin domain and N‐ and C‐terminal tails all having roles in the oligomer formation (Haslbeck et al , 2005). In addition to stress response, sHsps are produced during normal developmental stages in insects (Mason et al , 1984; Michaud et al , 1997; Joanisse et al , 1998; Shirk et al , 1998; Sonoda et al , 2006; Saravanakumar et al , 2008; Kokolakis et al , 2009), but their functional roles remain unclear.…”

Comparison of Biochemical Components within White and Brown Cysts in the Cereal Cyst Nematode Heterodera avenae

“…There are strong correlations between Aphelenchus auenae survival in dry air and glycerol and trehalose contents were observed . A large number of trehalose that accumulates in the hemolymph is derived from fat body glycogen in the diapausing pupae of Philosamia cynthia pryeri (Hayakawaa and Chino, 1981), which was studied by Saravanakumar et al (2008). The trehalase gene was expressed in non-diapause eggs of the multivoltine silkworm Bombyx mori for 9 days, whereas that in the diapause eggs was not upregulated.…”

Changes in diapause related gene expression pattern during early embryonic development in HCl-treated eggs of bivoltine silkworm Bombyx mori (Lepidoptera: Bombycidae)

“…The bivoltine silkworm eggs enter diapause and hatch after four months preservation under 5º C. Alternatively, the diapause can be broken by treating the eggs with HCl immediately after oviposition. Reports have indicated that Tre, GPase, G6PD and SDH genes expressed at different levels in various target tissues of B. mori are actively involved in the diapause process and in the eggs, diapausing is completed by 24-36 h (Sakano et al 2004;Saravanakumar et al 2008;Ponnuvel et al 2010). The present study is an analysis of the expression of selected metabolic enzymes, translational regulatory gene and HSP genes within 48 h of oviposition in both the diapause and HCl treated (non-diapause) bivoltine silkworm eggs.…”

“…As the onset of diapause occurs predominantly in the early stage, i.e., within 30h of oviposition, it is worth analyzing the differential gene expression at this crucial period to find out the significant up-as well as downregulation of diapause related genes involved in non-diapause process. Earlier findings indicated that few metabolic and heat shock protein genes were differentially expressed during the onset of diapause (Saravanakumar et al 2008;Ponnuvel et al 2010). Based on the available information, an attempt has been made to investigate the molecular aspects of these major genes involved in diapause phenomenon in HCl treated (non-diapause) and untreated (diapause) eggs during early embryogenesis.…”