An amphibian is a member of the vertebrate group containing frogs, salamanders and caecilians. Many have aquatic larvae and terrestrial adults, but life cycles vary. An aquatic-to-terrestrial transition is therefore a useful example rather than a universal definition.
A salamander is an amphibian with a typically elongated body and a tail retained in the adult. Development varies from metamorphosis to retention of larval features. This variation makes salamanders useful for comparing biological development and life-history evolution.
An Early Jurassic frog relative with a derived caudopelvic apparatus interpreted as consistent with jumping.
An Early Triassic stem frog from Madagascar with an anteriorly elongated ilium, a retained short tail and incompletely transformed limbs. CT redescription identified 15 presacral vertebrae rather than the traditional count of 14.
A salamander used experimentally to investigate limb regeneration and lineage contributions to the regenerative outgrowth.
A frog is an amphibian of the tailless adult group. Many species develop from aquatic tadpoles, while others have different reproductive modes. The adult’s jumping body plan and the larva’s feeding apparatus belong to distinct developmental stages.
Xenopus is a taxonomic genus of African clawed frogs used in experimental biology. Xenopus laevis is an important example. Its large egg cells and oocytes make manipulations of individual cells possible, allowing researchers to change a defined component and observe development or membrane function.
In John Gurdon's 1962 somatic cell nuclear transfer experiments, nuclei from intestinal epithelium of feeding tadpoles were introduced into eggs whose own nuclear contribution had been removed. A nuclear marker helped identify the donor origin, while embryonic-nucleus controls tested whether the recipient eggs and procedure could support development. Successful development showed that differentiation did not necessarily eliminate the nuclear information needed for other cell types.[ref]
The Developmental Capacity of Nuclei taken from Intestinal Epithelium Cells of Feeding Tadpoles by J. B. Gurdon. Materials and Methods, nuclear marker and embryonic controls; Normal tadpoles
A different use treats the oocyte as a test cell for a cloned membrane protein. The 1993 aquaporin-2 study introduced the channel's RNA into Xenopus oocytes and measured the resulting increase in water permeability. Comparing injected and control cells turns swelling in a defined external solution into evidence that a candidate protein can provide a pathway for water across a cell membrane.[ref]
Used here for the living-frog crown group, including the common ancestor of living frogs and every descendant.
A common name for several burrowing frogs. Their tadpoles include systems used to investigate environmentally induced resource-use phenotypes.
Xenopus laevis is a frog used in developmental biology, including the intestinal nucleus transfer experiment and Xenopus laevis egg extract preparations.
