title: A comparative analysis of frog early development.
abstract: The current understanding of Xenopus laevis development provides a comparative background for the analysis of frog developmental modes. Our analysis of development in various frogs reveals that the mode of gastrulation is associated with developmental rate and is unrelated to egg size. In the gastrula of the rapidly developing embryos of the foam-nesting frogs Engystomops coloradorum and Engystomops randi, archenteron and notochord elongation overlapped with involution at the blastopore lip, as in X. laevis embryos. In embryos of dendrobatid frogs and in the frog without tadpoles Eleutherodactylus coqui, which develop somewhat more slowly than X. laevis, involution and archenteron elongation concomitantly occurred during gastrulation; whereas elongation of the notochord and, therefore, dorsal convergence and extension, occurred in the postgastrula. In contrast, in the slow developing embryos of the marsupial frog Gastrotheca riobambae, only involution occurred during gastrulation. The processes of archenteron and notochord elongation and convergence and extension were postgastrulation events. We produced an Ab against the homeodomain protein Lim1 from X. laevis as a tool for the comparative analysis of development. By the expression of Lim1, we were able to identify the dorsal side of the G. riobambae early gastrula, which otherwise was difficult to detect. Moreover, the Lim1 expression in the dorsal lip of the blastopore and notochord differed among the studied frogs, indicating variation in the timing of developmental events. The variation encountered gives evidence of the modular character of frog gastrulation.
authors.affiliation: Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, Avenida 12 de Octubre 1076 y Roca, Quito, Ecuador. edelpino@puce.edu.ec
authors.forename: Eugenia M
authors.initials: EM
authors.lastname: del Pino
authors.forename: Michael
authors.initials: M
authors.lastname: Venegas-Ferrín
authors.forename: Andrés
authors.initials: A
authors.lastname: Romero-Carvajal
authors.forename: Paola
authors.initials: P
authors.lastname: Montenegro-Larrea
authors.forename: Natalia
authors.initials: N
authors.lastname: Sáenz-Ponce
authors.forename: Iván M
authors.initials: IM
authors.lastname: Moya
authors.forename: Ingrid
authors.initials: I
authors.lastname: Alarcón
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sudou
authors.forename: Shinji
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Masanori
authors.initials: M
authors.lastname: Taira
mesh_terms: D000818:Animals; D001001:Anura / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000166:cytology; D005306:Fertilization; D005775:Gastrula / Q000166:cytology / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D009420:Nervous System / Q000166:cytology / Q000196:embryology; D009672:Notochord / Q000166:cytology; D010063:Ovum / Q000166:cytology; D019170:Somites / Q000166:cytology; D014982:Xenopus laevis / Q000196:embryology
chemical_list: D018398:Homeodomain Proteins