<b>The analysis of complex developmental programmes: amphibian metamorphosis</b>

Kanamori, Akira; Brown, Donald D.

doi:10.1046/j.1365-2443.1996.d01-251.x

Cited by 25 publications

(10 citation statements)

References 56 publications

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“…In X. laevis, metamorphosis is three days long, and the end is characterized by the entire regression of the tail [45][46][47][48][49][50][51]. Amphibian metamorphosis is a good model to understand the mechanisms regulating PCD [52][53][54]. The tail regression implicates an apoptotic pathway inducible by T3 hormone and involving some cell death executioners [55].…”

Section: Several Aspects Of Apoptosis At Metamorphosismentioning

confidence: 99%

Apoptosis in amphibian development

Exbrayat¹,

Moudilou²,

Abrouk³

et al. 2012

ABB

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Amphibians and more particularly X. laevis are models often used for studying apoptosis during embryonic development. Using several methods, searchers determined the localization of programmed cell deaths (PCD). Several experimental methods also have been used to understand the regulatory mechanisms of apoptosis, throughout development, contributing to elucidate the general action of several genes and proteins. Apoptosis occurs very early, with a first program under control of maternal genes expressed before MBT, in order to eliminate damaged cells before gastrulation, and a second program at the onset of gastrulation. PCD is also observed during neurulation. Then, apoptotic cells are observed in amphibian organogenesis and metamorphosis. Results of these researches showed both importance of PCD for embryonic development, and the complexity of its regulation. Results obtained can be useful to understand others aspects of the importance of apoptosis, particularly pathological aspects.

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Section: Several Aspects Of Apoptosis At Metamorphosismentioning

confidence: 99%

Apoptosis in amphibian development

Exbrayat¹,

Moudilou²,

Abrouk³

et al. 2012

ABB

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“…Larval amphibian development is highly plastic, and it is regulated by thyroid hormone (TH) physiology (24)(25)(26)(27). Such plasticity is adaptive, and, in some cases, it allows tadpoles to increase their developmental rate in response to environmental risks such as pond desiccation (28)(29)(30).…”

mentioning

confidence: 99%

Developmental plasticity mirrors differences among taxa in spadefoot toads linking plasticity and diversity

Gómez-Mestre

Buchholz

2006

Proc. Natl. Acad. Sci. U.S.A.

162

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Developmental plasticity is found in most organisms, but its role in evolution remains controversial. Environmentally induced phenotypic differences may be translated into adaptive divergence among lineages experiencing different environmental conditions through genetic accommodation. To examine this evolutionary mechanism, we studied the relationship between plasticity in larval development, postmetamorphic morphology, and morphological diversity in spadefoot toads, a group of closely related species that are highly divergent in the larval period and body shape and are distributed throughout temperate areas of both the New and the Old World. Previous studies showed that accelerated metamorphosis is adaptive for desert-dwelling spadefoot toads. We show that even under common garden conditions, spadefoot toad species show divergent reaction norms for the larval period. In addition, experimentally induced changes in the larval period caused correlated morphological changes in postmetamorphic individuals such that long larval periods resulted in relatively longer hindlimbs and snouts. A comparative analysis of morphological variation across spadefoot toad species also revealed a positive correlation between the larval period and limb and snout lengths, mirroring the effects of within-species plasticity at a higher taxonomic level. Indeed, after Ϸ110 Ma of independent evolution, differences in the larval period explain 57% of the variance in relative limb length and 33% of snout length across species. Thus, morphological diversity across these species appears to have evolved as a correlated response to selection for a reduced larval period in desert-dwelling species, possibly diverging from ancestral plasticity through genetic accommodation.allometry ͉ genetic accommodation ͉ life-history evolution ͉ morphological diversity ͉ larval period

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“…. TRβ genes are indeed among the early TH response genes isolated from subtractive differential screens for TH target-genes (Kanamori and Brown, 1996). This upregulation is believed to result from TH-mediated induction of the promoters of both TRβ genes.…”

Section: Tr Expressionmentioning

confidence: 99%

Thyroid hormone receptor expression in the obligatory paedomorphic salamander Necturus maculosus

Vlaeminck-Guillem¹,

Safi²,

Guillem³

et al. 2006

Int. J. Dev. Biol.

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Amphibian metamorphosis is under the strict control of thyroid hormones (TH).These hormones induce metamorphosis by controlling gene expression through binding to thyroid hormone receptors (TRs). Necturus maculosus is considered to be an obligatory paedomorphic Amphibian since metamorphosis never occurs spontaneously and cannot be induced by pharmacological means. Since metamorphosis depends on the acquisition of response of tadpole tissues to thyroid hormone, we aimed to determine TR gene expression patterns in Necturus maculosus as well as the expression of two TH-related genes: Cytosolic Thyroid Hormone-Binding Protein (CTHBP)-M2-pyruvate kinase, a gene encoding a cytosolic TH binding protein and stromelysin 3, a direct TH target gene in Xenopus laevis. Tissue samples were obtained from specimens of Necturus maculosus. We performed in situ hybridization using non-cross-hybridizing RNA probes obtained from the cloned Necturus TRα and TRβ genes. We found clear expression of Necturus TRα gene in several tissues including the central nervous system, epithelial cells of digestive and urinary organs, as well as myocardium and skeletal muscle. TRβ was also expressed in the brain. In other tissues, hybridization signals were too low to draw reliable conclusions about their precise distribution. In addition, we observed that the expression of CTHBP and ST3 is largely distinct from that of TRs. The fact that we observed a clear expression of TRα and TRβ which are evolutionary conserved, suggests that Necturus tissues express TRs. Our results thus indicate that, in contrast to previously held hypotheses, Necturus tissues are TH responsive.

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The analysis of complex developmental programmes: amphibian metamorphosis

Cited by 25 publications

References 56 publications

Apoptosis in amphibian development

Apoptosis in amphibian development

Developmental plasticity mirrors differences among taxa in spadefoot toads linking plasticity and diversity

Thyroid hormone receptor expression in the obligatory paedomorphic salamander Necturus maculosus

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