Temporal responsiveness of the ovary of goldfish to gonatropin

Abstract

Female goldfish were acclimated to an 8 h light photoperiod and 14–15°C, and, in separate experiments, injected daily for 18 and 14 days with low doses of a partially purified salmon gonadotropin (sGtH) or a highly purified carp gonadotropin (cGtH), respectively at either the onset of light, or 4 or 8 h after the onset of light. The response to GtH injection was measured by the gonadosomatic index (GSI) and by histoiogical analyses of oocy te development. There was a response to sGtH injected at 8 h and to cGtH at 4 h and 8 h after the onset of light. Female goldfish acclimated to a 16 h light photoperiodand injected with low doses of cGtH at either the onset of light or at 4, 8, 12 or 16 h after the onset of light for 14 days had an increased GSI in response to the cGtH injected at 12 h after the onset of light. These results demonstrate that there is a daily variation in responsiveness of the ovary of goldfish to GtH.

Abstracting keywords:

• goldfish
• gonadotropin
• gonad responsiveness
• gonad recrudescence

Notes

Department of Zoology, University of Alberta, Edmonton, Alberta T6G 2E9 Canada.

Laboratoire de Physiologie des Poissons, Institut National de la Recherche Agronomique, Université de Rennes‐Beaulieu, 35031 Rennes Cedex, France.