Gene expression and its control agents in embryogenesis of Bombyxmori

建立了从家蚕卵中提取可翻译信使RNA的方法。采用后一种方法可以明确醛缩酶同工酶的切换模式，醛缩酶同工酶被选为基因表达研究的标记。在建立人类计划的基础上，即以人类全基因组测序为目标，提出了家蚕cDNA和基因组文库制备的范围。对主要的蛋黄蛋白——蛋特异蛋白（egg specific protein， ESP）进行了精确的转录、翻译和翻译后加工分析。此外，蛋黄蛋白的利用途径也开始被揭示出来；发现存在一种可以降解ESP的特定蛋白酶。这种酶表现出ESP链的有限断裂。这提供了在分子水平上卵黄蛋白利用的初始步骤的第一个理解。卵巢外甾体的存在是已知的。主要种类为偶联型，更多的可能是本研究中检测到的储存形式和水解酶可能在胚胎发生过程中提供游离的、活性的外甾体起关键作用。家蚕滞育的启动是由一个单基因pnd^+控制的。后一基因的产物经双向凝胶电泳鉴定为一种蛋白质。从蛋白质合成和RNA合成两方面讨论了后一基因及其产物在滞育开始时的作用方式。关于滞育的终止，我们发现所谓滞育发育结束的信号是酯酶a的活化，这种酶经结晶后发现是一种计时分子，它在一定条件下体外激活自己，类似于蚕滞育卵的冷活化。核苷酸碱基，特别是5-甲基胞嘧啶改变了蚕卵的冬眠程序。这些药物可以作为干扰截流系统的方便实验药物进行分析。少

The method for extraction of translatable messenger RNA from the eggs of Bombyx mori was established. By using the latter method the mode of switchover of aldolase isozymes, chosen as a marker for gene expression study, could be clarified. Based on the effort to set up the human project, i.e. aiming at the sequencing of the whole genome of man, the scope of preparing the cDNA and genomic libraries of the silkworm was proposed. As to the major yolk protein named egg specific protein (ESP), the relevant transcription, translation and posttranslational processing were precisely analyzed. Moreover, the way of yolkprotein utilization has begun to be uncovered; a specific protease which can degrade ESP was found to be present. This enzyme exhibit a limited break of the ESP chain. This provides the first understanding of the initial steps of yolk protein utilization at the molecular level. The presence of ovarian ecdysteroids has been known. The major species were found to be conjugate types, … More which may be the storage forms and hydrolysis enzymes detected in the present study might have critical roles to provide free, thus active, ecdysteroids during embryogenesis. The initiation of diapause in B. mori is known to be controlled by a single gene pnd^+. The product of the latter gene was suggested to be a protein as separated by two-dimensional gel electrophoresis. The mode of action of the latter gene (and its product) was discussed in terms of protein synthesis and RNA synthesis at the period of diapause onset. As to the break of diapause a signal of the end of the so-called diapause development has been found to be the activation of esterase A. This enzyme was crystallized and revealed to be a time-measuring molecule which activates itself in vitro under the specified conditions minicking the cold activation of diapausing eggs of the silkworm. The nucleotide bases in particular 5-methylcytosine changed the hibernating program of the silkworm eggs. These agents might serve as convenient experimental drugs that disturb the diapasue system to be analyzed. Less