SEVERAL BIOCHEMICAL-ALTERATIONS FROM LARVAL TO ADULT TYPES ARE INDEPENDENT ON MORPHOLOGICAL METAMORPHOSIS IN A SALAMANDER, HYNOBIUS-RETARDATUS

Biochemical transitions from larval to adult types, such as changes in hemoglobin subunits and pattern of excretion of nitrogen wastes, were studied during ontogeny of a salamander, Hynobius retardatus, which h ad been reported to show neotenic reproduction. A transition of hemogl obin subunits in normally metamorphosing and metamorphosed, and T-4-in duced precociously metamorphosed H. retardatus was analyzed using SDS- PAGE. The transition of hemoglobin subunits from larval to adult types occurred on the same time schedule in both normally metamorphosing an d precociously metamorphosed animals. A changeover from ammonotelism t o ureotelism was analyzed by determining amounts of ammonia and urea e xcreted from normal and metamorphosis-arrested animals. A basic change over from ammonotelism to ureotlism also occurred even in metamorphosi s-arrested, aquatic larvae, on the similar time schedule in normally m etamorphosing and metamorphosed animals. Because the transition of hem oglobin subunits in the metamorphosis-arrested larvae has been reporte d to occur on the same time schedule as in the controls, it is conclud ed that either transitions of hemoglobin subunits from larval to adult or pattern of nitrogen excretion from ammonotelism to ureotelism are independent on the morphological metamorphosis in H. retardatus. The s ubstantial separation of biochemical ''metamorphosis'' from morphologi cal metamorphosis will explain a possible cause of neoteny which has b een reported in this species.