DIFFERENTIAL EXPRESSION OF THE Bombyx mori DIAPAUSE‐TERMINATION TIMER GENE Ea4 IN DIAPAUSE‐INDUCING TEMPERATURE AND PHOTOPERIOD

Abstract

Diapause in Bombyx mori eggs is induced by temperature and photoperiod at the stage of embryonic development in the maternal generation. In those diapause eggs, Esterase-A4 is suggested to serve as a diapause-termination timer (TIME-EA4), because its ATPase activity shows an interval-timer elevation after acid treatment or chilling of eggs to break diapause. To clarify whether the timed ATPase activity of TIME-EA4 is related to its gene (Ea4) expression, we analyzed Ea4 mRNA of eggs in diapause-inducing environmental conditions. Reverse transcription PCR (RT-PCR) analysis showed that the level of Ea4 mRNA was lower in 15DD than in 25LL (P < 0.01) or in 20LD (P < 0.01) but did not oscillate when photoperiod and temperature periodically oscillated (P > 0.05). Furthermore, expressed sequence tag profile and gene microarray analysis demonstrated that Ea4 showed stage-specific and tissue-specific expression during postembryonic stages, high Ea4 mRNA in the spinning and eclosion stages, and in integument and head, but low in gonads of fifth-instar day-3 larvae. Then we analyzed the relationship between TIME-EA4 ATPase activities and Ea4 gene expression. The ATPase activities in diapause eggs laid by the resultant adults transiently elevated after treatments to break diapause, that is, at 1.5 h after common-acid treatment and day 13 after chilling at 5°C. However, these elevations of enzyme activities were not accompanied by any increases in Ea4 mRNA levels. In conclusion, the termination of the Bombyx embryonic diapause is related to TIME-EA4 but not to its gene expression.

CHITIN SYNTHASE B: A MIDGUT‐SPECIFIC GENE INDUCED BY INSECT HORMONES AND INVOLVED IN FOOD INTAKE IN Bombyx mori LARVAE

“…Therefore, we inferred that BmChsB is a gene expressed specifically in the midgut. Its feeble expression in gonads is actually a very common phenomenon shared by many tissue‐specific genes of the silkworm (Gan et al., ; Xu et al., ).…”

“…Therefore, we inferred that BmChsB is a gene expressed specifically in the midgut. Its feeble expression in gonads is actually a very common phenomenon shared by many tissue-specific genes of the silkworm (Gan et al, 2010;Xu et al, 2012). Based on the findings described above, we investigated the BmChsB expression profiles in the midgut during molting and the mulberry-leaf ingestion processes.…”

IMPACT OF CYCLICAL CHANGES IN TEMPERATURE ON CIRCADIAN CLOCK GENES EXPRESSION IN Bombyx BmN CELLS

“…In recent years, many studies have focused on the effects of lighting on animal behavior and internal physiology and metabolism at the genetic and protein levels (Edery, 2000;Glaser and Stanewsky, 2005;Lohmann et al, 2007;Fuller et al, 2008). Insects are cold-blooded, thus temperature is directly involved in the regulation of physiological behavior mechanisms including hatching and feeding, growth and metamorphosis, reproduction and diapause, and migration and calling (Zhu et al, 2008a(Zhu et al, /2008bTanaka and Watari, 2011;Xu et al, 2012;Hosseinzade et al, 2014;Liao et al, 2014;Soltani Orang et al, 2014). A Drosophila study found that cyclical changes in temperature with differences of 2-3°C reset and synchronized the circadian clock (Gentile et al, 2013).…”