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.Brachyury ͉ Gastrotheca ͉ Lim1

Transcription factors Mix1 and VegT, relocalization of vegt mRNA, and conserved endoderm and dorsal specification in frogs

“…The localities for frog collections in Ecuador, frog maintenance, and embryo culture were described (20,29,30). Frog collection was authorized by the Ministry of the Environment of Ecuador, authorization 016-IC-FAU-DNBAP-MA.…”

“…Embryos of Eleutherodactylus coqui and X. laevis came from laboratory maintained animals at Duquesne University and at the University of Tokyo, respectively. Gastrulae were staged according to normal tables of stages (20,(29)(30)(31). The Faculty of Exact and Natural Sciences of the Pontificia Universidad Católica del Ecuador approved procedures for the maintenance and handling of frogs and embryos.…”

“…S1A) (19). The analyzed frogs were the foam-nesting túngara frog Engystomops randi (Leptodactylidae), the poison-arrow frog E. machalilla (Dendrobatidae), the marsupial frog G. riobambae (Hemiphractidae), the frog without tadpoles E. coqui (Eleutherodactylidae: Terrarana), and the aquatic frog X. laevis (Pipidae) (20). The localization of vegt and mix1 mRNAs in X. laevis embryos were reexamined for comparison.…”

Desarrollo neural, somitogénesis y morfología interna de los embriones de Hyloxalus vertebralis y Dendrobates auratus (Anura: Dendrobatidae)

“…a De acuerdo con: del Pino et al, 2007;Moya, 2005;Rafinska, 1991. b Tiempo desde la fertilización hasta el final de la gastrulación (del Pino et al, 2007;Michael, 1981).…”

“…b Tiempo desde la fertilización hasta el final de la gastrulación (del Pino et al, 2007;Michael, 1981). c Abreviaturas: rc, rotación celular; ic, interdigitación celular.…”