Adult Rudiment Formation and Thyroid Hormones in Sea Urchin Larvae

本文研究了甲状腺激素（T_4和T_3）对五种海胆（Hemicentrotus pulcherrimus、Pseudocentrotus depressus、Anthocidaris crassispina和Peronera japonica）生长发育的影响。结果表明，甲状腺激素促进日本鲈的发育，其含量随发育的进行而增加，在变态前达到最大值。硫脲、高氯酸钾等抑制剂使白斑海参在变态前的激素含量保持在较低水平，并延长了变态的持续时间，表明白斑海参幼虫通过吸收海水中的碘，在体内合成激素，调节自身的发育。甲状腺激素可诱导黑木耳幼虫退化，且在发育后期作用尤为显著。而这些激素对海燕的发育没有影响，并且在整个胚胎和幼虫发育过程中激素含量都很低，这一结果对研究甲状腺激素在棘皮动物中的分布具有重要意义。

We ahve investigated the effect of thyroid hormones (T4 and T3) on development of sea urchins Hemicentrotus pulcherrimus, Pseudocentrotus depressus, Anthocidaris crassispina and Peronera japonica. Subsequently, we studied the effect of the hormones on the other species of Echinodermates.Thyroid hormones accelerated the development of Perona japonica and the contents of the hormones increased following the development and reached maximum just before metamorphosis. However, inhibitors such as thiourea and potassium perchlorate kept the low level of the hormone contents even before metamorphosis and prolonged the duration to metamorphosis, indicating that larvae synthesize the houmones within the larval body by taking up iodine from sea water and regulate own development.The effect of the hormones studied on development of Holothuria leucospilota which has long period of auricularia larva and short doliolaria larva. Thyroid hormones induced degeneration of auricularia larva and the effect was especially significant in later stage of development. However, the hormones had no effect on development of Asterina pectinifera and the level of hormone content was very low throughout the development of embryos and larvae.These results show the significance of phylogenetic investigation for the distribution of thyroid hormones in Echinodermates.