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MICROGRAVITY EFFECTS ON FERTILIZED EGGS HAVE NO INCIDENCE, AFTER LANDING, ON THE FURTHER LARVAL DEVELOPMENT AND REPRODUCTION IN THE AMPHIBIAN PLEURODELES WALTL.    H. Membre, A. Bautz, D. Durand, C. Aimar, A.M. Bautz and C. Dournon.  EA 2401 Gйnйtique et Interactions Cellulaires en Reproduction, Univ Henri Poincarй, Nancy, France. 

Our goal was to show if natural fertilization and normal development could occur in space and after landing. Female Pleurodeles were inseminated on the ground, then laying was induced by hormonal treatment in space. Eggs were obtained at a 18C constant temperature in the three FERTILE experiments during the 1996 Cassiopйe, 1998 Pйgase, and 1999 Perseus French missions aboard the Mir station. The distribution of peptidase-1 genes, a polymorphic sex linked enzyme, in progenies stated the actual fertilization in microgravity and ruled out parthenogenesis or gynogenesis. During the first cleavage of segmentation, microvilli of µg-, space-1g- and ground-1g-eggs, observed under SEM in the vicinity of the animal pole, were different in length, diameter and distribution, attesting an influence of microgravity on these cells. Recovered at the hatching stages after landing and reared in the laboratory at room temperature, the young larvae underwent metamorphosis and became adult without obvious abnormalities. The rate of development and the morphology were similar in these animals and in controls. As expected, the sex ratio was equal to 1. No sex reversal was observed. Born-in-space males were firstly mated with ground-control females, and then, depending on their fertility, mated with born-in-space females. All the mating gave progenies that normally developed. Analysis of the F2 generation is in process.

(Supported by CNES: 96/0265, 793/98/7208, 97/071 and 793/99/7443)