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Limb development in a nonmodel vertebrat ... ng frog Eleutherodactylus coqui
Limb development in a nonmodel vertebrate, the direct-developing frog Eleutherodactylus coqui.
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Mechanisms that mediate limb development are regarded as highly conserved among vertebrates, especially tetrapods. Yet, this assumption is based on the study of relatively few species, and virtually none of those that display any of a large number of specialized life-history or reproductive modes, which might be expected to affect developmental pattern or process. Direct development is an alternative life history found in many anuran amphibians. Many adult features that form after hatching in metamorphic frogs, such as limbs, appear during embryogenesis in direct-developing species. Limb development in the direct-developing frog Eleutherodactylus coqui presents a mosaic of apparently conserved and novel features. The former include the basic sequence and pattern of limb chondrogenesis, which are typical of anurans generally and appear largely unaffected by the gross shift in developmental timing; expression of Distal-less protein (Dlx) in the distal ectoderm; expression of the gene Sonic hedgehog (Shh) in the zone of polarizing activity (ZPA); and the ability of the ZPA to induce supernumerary digits when transplanted to the anterior region of an early host limb bud. Novel features include the absence of a morphologically distinct apical ectodermal ridge, the ability of the limb to continue distal outgrowth and differentiation following removal of the distal ectoderm, and earlier cessation of the inductive ability of the ZPA. Attempts to represent tetrapod limb development as a developmental module must allow for this kind of evolutionary variation among species.
Hanken J, Carl TF, Richardson MK, Olsson L, Schlosser G, Osabutey CK, Klymkowsky MW
The Journal of experimental zoology
2001-12-15 00:00
291
4
375-88
Animals,Bufonidae,Cell Differentiation,Chondrogenesis,Embryonic Development,Evolution,Gene Expression Regulation, Developmental,Hindlimb,Metamorphosis, Biological
Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA hankenoebharvardedu
J. Exp. Zool.
NIGMS GM 54001
0022-104X
10.1002/jez.1136
626
True
11754016
