A comparative analysis of frog early development.
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.
del Pino
Eugenia M
EM
Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, Avenida 12 de Octubre 1076 y Roca, Quito, Ecuador. edelpino@puce.edu.ec
Venegas-Ferrín
Michael
M
Romero-Carvajal
Andrés
A
Montenegro-Larrea
Paola
P
Sáenz-Ponce
Natalia
N
Moya
Iván M
IM
Alarcón
Ingrid
I
Sudou
Norihiro
N
Yamamoto
Shinji
S
Taira
Masanori
M
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
D018398:Homeodomain Proteins