UPTAKE AND LOCALIZATION OF

The meiotic inducing hormone, 1-methyladenine, first isolated from starfish has been implicated to play some role in the gamete maturation of a number of marine invertebrates. However, there have been controversial and sometimes opposite conclusions due to the fact that there is no direct bioassay system other than in starfish. Using 3 H-1-methyladenine, we demonstrated that the hormone was localized exclusively in the outer epithelial cells of gonads of sea urchins as revealed by autoradiography. Uptake by the testes differs from that by the ovaries. Competition data show that the uptake of the labelled hormone is real and also show the different rates of uptake by the gonads of male and female sea urchins. It is concluded that 1-MA may exhibit differential effects on cell types due to their differentiated state and the seasonal variations of the organisms. The action of 1-MA is, therefore, multiple and not restricted to the gametes although its action would ultimately result in gamete maturation.