title: [Adaptive features of life history for space experiments seen in Rana tagoi tadpoles].
abstract: We propose to use the physiological responses of tadpoles in space to study the effects of gravity at the organismal level. The tadpoles we propose for study, Rana tagoi, have naturally transparent abdominal walls, permitting viscera, such as heart and intestine, to be easily observed. Rana tagoi is a mountainous species that lays eggs in water, typically at crevasses in rocky substrates. Its eggs are rich in yolk, and tadpoles can grow without being fed (except own feces). However, they will eat when presented food. Coprophagy in these tadpoles can be clearly seen when small amount of food is fed. Abdominal wall remains transparent until metamorphosis. Intestinal and cardiac activity are clearly visible and can be documented by video without any invasive procedures. Because of the limited requirements on the digestive system in this species, their intestine does not elongate much when the tadpoles grow up. Even in this species, periodical contractions occur in the intestine throughout the larval period. Space experiments using R. tagoi tadpoles are promising in terms of scientific merit and technical feasibility. With this species it is possible to study the effects of gravity on visceral physiology and metamorphosis. Rana tagoi tadpoles would be a good model for space experiments where only the basic minimum capability of life support function (e.g., temperature and oxygen control), could be provided.
authors.affiliation: Inst. Space Astron. Sci.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Yamashita
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kashiwagi
authors.forename: Makiko
authors.initials: M
authors.lastname: Shigenari
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Wassersug
authors.forename: Tomio
authors.initials: T
authors.lastname: Naitoh
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D007422:Intestines / Q000254:growth & development / Q000502:physiology; D007814:Larva / Q000254:growth & development / Q000502:physiology; D011898:Ranidae / Q000254:growth & development / Q000502:physiology*; D013026:Space Flight; D014893:Weightlessness