Cruz J, Martín D, Pascual N, Maestro J L, Piulachs M D, Bellés X
Department of Physiology and Molecular Biodiversity, Institut de Biologia Molecular de Barcelona (CSIC), Jordi Girona 18, 08034 Barcelona, Spain.
Insect Biochem Mol Biol. 2003 Dec;33(12):1219-25. doi: 10.1016/j.ibmb.2003.06.004.
We aimed to elucidate why cockroaches do not produce vitellogenin in immature stages, by studying the appearance of vitellogenin mRNA in larvae of Blattella germanica. Treatment of female larvae in any of the last three instars with 1 microg of juvenile hormone (JH) III induces vitellogenin gene transcription, which indicates that the fat body is competent to transcribe vitellogenin at least from the antepenultimate instar larvae. In untreated females, vitellogenin production starts on day 1 after the imaginal molt, when corpora allata begin to synthesize JH III at rates doubling the maximal of larval stages. This coincidence suggests that the female reaches the threshold of JH production necessary to induce vitellogenin synthesis on day 1 of adult life. These data lead to postulate that larvae do not synthesize vitellogenin simply because they do not produce enough JH, not because their fat body is incompetent.
我们旨在通过研究德国小蠊幼虫中卵黄原蛋白mRNA的出现情况，阐明蟑螂在未成熟阶段不产生卵黄原蛋白的原因。用1微克保幼激素（JH）III处理最后三龄幼虫中的任何一龄的雌性幼虫，均可诱导卵黄原蛋白基因转录，这表明脂肪体至少从倒数第二龄幼虫开始就有能力转录卵黄原蛋白。在未处理的雌性蟑螂中，卵黄原蛋白的产生在成虫蜕皮后的第1天开始，此时咽侧体开始以幼虫阶段最大值两倍的速率合成JH III。这种巧合表明，雌性蟑螂在成年生活的第1天达到了诱导卵黄原蛋白合成所需的保幼激素产生阈值。这些数据表明，幼虫不合成卵黄原蛋白仅仅是因为它们产生的保幼激素不足，而不是因为它们的脂肪体没有能力。
