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Diapause Termination (diapause + termination)
Selected AbstractsMyocyte enhancer factor 2 (MEF2) is a key modulator of the expression of the prothoracicotropic hormone gene in the silkworm, Bombyx moriFEBS JOURNAL, Issue 15 2005Kunihiro Shiomi Prothoracicotropic hormone (PTTH) plays a central role in controlling molting, metamorphosis, and diapause termination in insects by stimulating the prothoracic glands to synthesize and release the molting hormone, ecdysone. Using Autographa californica nucleopolyhedrovirus (AcNPV)-mediated transient gene transfer into the central nervous sytem (CNS) of the silkworm, Bombyx mori, we identified two cis -regulatory elements that participate in the decision and the enhancement of PTTH gene expression in PTTH-producing neurosecretory cells (PTPCs). The cis -element mediating the enhancement of PTTH gene expression binds the transcription factor Bombyx myocyte enhancer factor 2 (BmMEF2). The BmMEF2 gene was expressed in various tissues including the CNS. In brain, the BmMEF2 gene was expressed at elevated levels in two types of lateral neurosecretory cells, namely PTPCs and corazonin-like immunoreactive lateral neurosecretory cells. Overexpression of BmMEF2 cDNA caused an increase in the transcription of PTTH. Therefore, BmMEF2 appears to be particularly important in the brain where it is responsible for the differentiation of lateral neurosecretory cells, including the enhancement of PTTH gene expression. This is the first report to identify a target gene of MEF2 in the invertebrate nervous system. [source] Synchronized diapause termination of the peach twig borer Anarsia lineatella (Lepidoptera: Gelechiidae): Brownian motion with drift?PHYSIOLOGICAL ENTOMOLOGY, Issue 1 2010PETROS T. DAMOS The course of diapause development is studied for the first time for Anarsia lineatella (Zeller) (Lepidoptera: Gelechiidae) under field and laboratory conditions for three successive years (2005,2007) in northern Greece. Photoperiod has a significant influence on diapause termination and the mean number of days to pupation decreases progressively throughout the winter season. Cold storage, for at least 30 days at 4°C, results in a synchronized reactivation of the larvae, with the developmental time of larvae chilled for 45 and 60 days at 4°C becoming significantly shorter. A theoretical stochastic description of the effect of chilling on diapause termination is attempted. Larvae have discrete ,physiological stages' with different degrees of diapause intensity, and the insect passes through those stages with a probability distribution S(t) that evolves over time. This pattern of progressive transition is similar to Brownian motion and finally leads to a successfully synchronized diapause break in spring. Hence, A. lineatella overwinters in a weak diapause state and may complete diapause development in late January, although it shows synchronized termination in early February, after the experience of essential chilling. [source] Metabolism of hydrogen peroxide between diapause and non-diapause eggs of the silkworm, Bombyx Mori during chilling at 5°CARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2010L.C. Zhao Abstract When diapause and non-diapause eggs of the same bivoltine strain of Bombyx mori were chilled at 5°C for more than 30 days, the hatchability of diapause eggs increased while that of non-diapause eggs decreased, respectively. To investigate the relationship between effects of chilling on the hatchability and the metabolism of hydrogen peroxide (H2O2), content of H2O2 and activities of superoxide dismutase (SOD), xanthine oxidase (XO), and catalase (CAT) between diapause and non-diapause eggs were determined during the chilling at 5°C. The significant enhancement of H2O2 occurred prior to the quick increase of the hatchability in diapause eggs and coincided with the quick decline of the hatchability in non-diapause eggs, respectively. Diapause eggs contained significantly higher H2O2 and XO activity and lower CAT activity compared to non-diapause eggs. Our results showed that there were significant differences in the metabolism of H2O2 between diapause and non-diapause eggs during chilling and that significant enhancement of H2O2 may be involved in the diapause termination of diapause eggs and the cell damage of non-diapause eggs. © 2010 Wiley Periodicals, Inc. [source] | ||||||||||