Effect of juvenile hormone on DNA synthesis during embryogenesis inAcheta domesticus.

1) The effect of juvenile hormone on embryonic development in the cricket,Acheta domesticus, was investigated. Application of 1 to 2.5 μg of methyl 12,14-dihomojuvenate (cecropia juvenile hormone) in 1 μl of acetone to 7-day-old cricket embryos inhibited their further growth. In such embryos, differentiation of some of the embryonic organs and tissues such as nerves, muscles and cuticular structures continued. However, embryonic growth was arrested, their morphology was abnormal and they failed to hatch. 2) Lipid extracts from adult maleHyalophora cecropia which possess juvenile hormone activity also showed similar effects on embryonic development. But lipid extracts prepared from allatectomized adult maleH. cecropia lacking juvenile hormone activity, did not inhibit embryonic development. 3) DNA synthesis in the embryonic tissues of the JH-treated and control embryos was investigated using an autoradiographic method of determination of H3 thymidine incorporation into nuclear DNA. The results showed that DNA synthesis in epidermal and mesenchymal cells of the cricket embryo decreased gradually after application of 1 μg of JH to 7-day-old embryos and ceased within 6 days after application of JH. 4) From these observations it is suggested that JH may inhibit embryonic development by suppression of DNA synthesis and cell divisions.