title: Effects of hypergravity environments on amphibian development, gene expression and apoptosis.
abstract: This study investigates how rearing under conditions of hypergravity affects amphibian development, Xotx2 and Xag1 gene expression and apoptosis. Uncleaved Xenopus laevis eggs 20 min after insemination, 2 cell stage embryos, and gastrula stage embryos were raised at 2G and 5G, while controls were raised in normal gravity. Apoptosis in brain and eye inner structures of hatching embryos was scored using the TUNEL staining method, and gene expression in tail-bud embryos was analyzed by whole-mount in situ hybridization. Results showed that: (1) 5G retarded the development of eggs and embryos and induced microcephaly and microphthalmia. (2) 5G suppressed the expression of the two genes, Xotx2 (involved in fore- and midbrain and eye development) and Xag1 (regulating cement gland formation). (3) Eggs and 2 cell stage embryos raised at 5G showed a greater extent of brain and eye apoptosis compared with controls, while those raised at 2G showed no significant difference. These findings suggest that high gravity suppresses certain gene functions and induces abnormal apoptosis in brain and eyes, resulting in developmental retardation and various morphological abnormalities.
authors.affiliation: Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashihiroshima 739-8526, Japan.
authors.forename: Satomi
authors.initials: S
authors.lastname: Kawakami
authors.forename: Keiko
authors.initials: K
authors.lastname: Kashiwagi
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Furuno
authors.forename: Masamichi
authors.initials: M
authors.lastname: Yamashita
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kashiwagi
mesh_terms: D000818:Animals; D017209:Apoptosis; D001921:Brain / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D002470:Cell Survival; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D005123:Eye / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D018471:Hypergravity; D017403:In Situ Hybridization / Q000379:methods; D020287:In Situ Nick-End Labeling / Q000379:methods; D051857:Otx Transcription Factors / Q000235:genetics; D029867:Xenopus Proteins / Q000235:genetics; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics*
chemical_list: D051857:Otx Transcription Factors; C497661:Otx2 protein, Xenopus; C113450:XAG-1 protein, Xenopus; D029867:Xenopus Proteins