[Interpersonal differentiation of the enzymatic pattern in the polymorphic hydroidHydractinia echinata]

Interpersonal differentiation between gasterozooids and gonozooids, inHydractinia echinata, is reflected by the pattern of extractable enzyme activities. With regard to their activity levels in the different hydranths the enzymes can be arranged in two groups. In the first group the specific activities are highest in gasterozooids and decline in the order gasterozooids>male gonozooids>female gonozooids. This group includes GAPDH, LDH, ICDH, and GPT. The activities of the second group are highest in female polyps and display the inverse sequence. This group comprises CS, GOT, and GLDH. When the GAPDH levels, taken as 100 pc each, are chosen as point of reference only this second sequence can be established and is now represented by MDH, ICDH, and G-6-PDH as well. 6-PGDH activity could not be determined in adult hydranths.According to the ratio of GAPDH/CS and the LDH level the gasterozooids prefer the anaerobic glycolytic pathway whereas in the sexual hydranths relatively more substrate is supplied at the disposal of the citrate cycle. Two metabolites of the citrate cycle, ketoglutarate and succinate, are known to promote the transformation of nutritive zooids into sexual zooids. The differences observed in the activities of GOT, GLDH, and ICDH, therefore, may be correlated not only with the production of gonocytes but also with the specific type of differentiation which in sexual hydranths is governed by a specific morphogen.