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)对海胆斑海胆、矮球海胆、粗刺花球海胆和日本贻贝发育的影响。随后，我们研究了激素对其他棘皮动物的影响。甲状腺激素促进了日本贻贝的发育，激素含量随着发育而增加，并在变态前达到最大值。而硫脲和高氯酸钾等抑制物在变态前仍保持较低的激素水平，延长了变态持续时间，说明幼虫通过摄取海水中的碘来合成体内荷尔蒙，调节自身发育。甲状腺激素诱导黑木耳幼虫退化，在发育后期影响尤为明显。但是，这些激素对海星藻的发育没有影响，而且在整个胚胎和幼虫发育过程中激素含量很低，这些结果表明系统发育研究对棘皮动物甲状腺激素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.