SWIMMING KINEMATICS AND RESPIRATORY BEHAVIOR OF XENOPUS-LAEVIS LARVAERAISED IN ALTERED GRAVITY

We examined the respiratory behaviours and swimming kinematics of Xeno pus laevis tadpoles hatched in microgravity (Space Shuttle), simulated microgravity (clinostat) and hypergravity (3g centrifuge), All observ ations were made in the normal 1 g environment. Previous research has shown that X. laevis raised in microgravity exhibit abnormalities in t heir lungs and vestibular system upon return to 1 g. The tadpoles rais ed in true microgravity exhibited a significantly lower tailbeat frequ ency than onboard 1 g centrifuge controls on the day of landing (day(0 )), but this behaviour normalized within 9 days, The two groups did no t differ significantly in buccal pumping rates. Altered buoyancy in th e space-flight microgravity tadpoles was indicated by an increased swi mming angle on the day after landing (day(1)), Tadpoles raised in simu lated microgravity differed to a greater extent in swimming behaviours from their 1 g controls. The tadpoles raised in hypergravity showed n o substantive effects on the development of swimming or respiratory be haviours, except swimming angle. Together, these results show that mic rogravity has a transient effect on the development of locomotion in X . laevis tadpoles, most notably on swimming angle, indicative of stunt ed lung development. On the basis Of the behaviours we studied, there is no indication of neuromuscular retardation in amphibians associated with embryogenesis in microgravity.