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Akira Mizoguchi 《Physiological Entomology》2017,42(3):239-245
Many insects undergo diapause to survive adverse seasons. Although the mechanism of diapause induction is the subject of extensive study, that of diapause termination remains poorly understood. In the present study, we show the endocrine processes leading to the termination of pupal diapause in Mamestra brassicae. Diapause of this insect is terminated if the pupae are exposed to a low temperature for several weeks. During this period, the prothoracic glands (PGs) of pupae acquire the potential to secrete sufficient ecdysteroids necessary for inducing adult development. The main endocrine changes observed under the low temperature conditions are: (i) the increase in activity of the PGs in two steps; (ii) the increase in responsiveness of the glands to prothoracicotropic hormone (PTTH); and (iii) two‐step increase in PTTH gene expression in the brain. The timing of the first and second increases in PG activity roughly coincides with that of the two steps of increase in PTTH gene expression, and the timing of the increase in the responsiveness of the PGs to PTTH coincides with the second, larger increase in PTTH gene expression. The ablation of the PGs prior to cooling pupae does not affect the increase in PTTH gene expression, whereas brain removal results in a failure to increase PG activity, strongly suggesting that PTTH is the master regulator of diapause development and termination. 相似文献
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A partial swine cDNA which encodes the functional domain of PIT-1 was isolated by the polymerse chain reaction (PCR). The swine PIT-1 cDNA clone is 95% identical at the protein level to the rat Pit-1 gene. Thus, Pit-l's known function in control of rat growth hormone and prolactin expression is likely to be conserved in swine. This swine cDNA clone was used to investigate genetic variability at PIT-1 in several American and Chinese breeds. Polymorphic BamIII fragments were found in pure-bred Meishan animals (n= 13), but only monomorphic fragments in five American breeds (n= 36). 相似文献
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Jonathan H. Clarke Judith I. Laurie Harry J. Gilbert Geoffrey P. Hazlewood 《FEMS microbiology letters》1991,83(3):305-309
Cellulomonas fimi genomic DNA encoding xylanase activity has been cloned and expressed in Escherichia coli. As judged by DNA hybridization and restriction analysis, twelve xylanase-positive clones carried a minimum of four different xylanase (xyn) genes. The encoded enzymes were devoid of cellulase activity but three of the four bound to Avicel. 相似文献
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M. Dittrich 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1995,177(2):207-217
Color induction in the honeybee is investigated in color discrimination experiments. An individual bee walks in a dark arena and is trained to a self-luminant stimulus presented from below. In the dual-choice tests the dark background is replaced by a colored induction stimulus. Choice behavior is recorded by TV camera and analyzed by computer. Successive color induction is separated from simultaneous induction by analysis of the walking paths. Only successive color induction occurs. Simultaneous effects are not observed. That is a stimulus acts as a color inducing stimulus only when the bee crosses this stimulus. Thus, the color perceived by a given eye region is found to be dependent on the viewing history, but not on the stimuli presented simultaneously on neighboring parts of the retina. Color induction in the honeybee described in terms of selective sensitivity decrease (adaptation) does not explain all behavioral effects induced by the stimulus. The time course of successive color induction is calculated from the exposure times to the induction stimulus and from the choice behavior. The data suggest that color induction is complete after a few seconds. Photoreceptor adaptation is sufficient to explain the observed time course. 相似文献
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Exploiting DELLA Signaling in Cereals 总被引:1,自引:0,他引:1
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Ralf Uptmoor Tobias Schrag Hartmut Stützel Elisabeth Esch 《Molecular breeding : new strategies in plant improvement》2008,21(2):205-216
Studying quantitative traits is complicated due to genotype by environment interactions. One strategy to overcome these difficulties
is to combine quantitative trait loci (QTL) and ecophysiological models, e.g. by identifying QTLs for the response curves
of adaptive traits to influential environmental factors. A B. oleracea DH-population segregating for time to flowering was cultivated at different temperature regimes. Composite interval mapping
was carried out on the three parameters of a model describing time to flowering as a function of temperature, i.e. on the
intercept and slope of the response of time to floral induction to temperature and on the duration from transition to flowering.
The additive effects of QTLs detected for the parameters have been used to estimate time to floral induction and flowering
in the B. oleracea DH-population. The combined QTL and crop model explained 66% of the phenotypic variation for time to floral induction and
56% of the phenotypic variation for time to flowering. Estimation of time to floral induction and flowering based on environment
specific QTLs explained 61 and 41% of the phenotypic variation. Results suggest that flowering time can be predicted effectively
by coupling QTL and crop models and that using crop modelling tools for QTL analysis increases the power of QTL detection. 相似文献