Mechanisms of Amphibian Metamorphosis: Hormones

Kollros, Jerry J.

doi:10.1093/icb/1.1.107

Cited by 158 publications

(54 citation statements)

References 17 publications

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“…For RIA measurements, [ 125 I]T 4 or -T 3 was added to the methanol homogenates at a concentration of 5-10 pM, the precipitate was removed by centrifugation, and the methanol evaporated by using a vacuum centrifuge. Samples were diluted to 1 ml with 0.1 M sodium barbital (pH 8.6) for T 4 or 0.02 M sodium phosphate (pH 7.5), containing 0.02 M EDTA and 0.75% sodium salicylate, for T 3 . The solutions were transferred to Ab-coated tubes (ICN).…”

Section: Growth Of Tadpoles On Inhibitors and Assays For Radioactive Andmentioning

confidence: 99%

“…Limb buds and tails express D2 early and late in metamorphosis, respectively, correlating with the time that these organs undergo TH-induced change. T 3 is required to complete metamorphosis because the peak concentration of T 4 that is reached at metamorphic climax cannot induce the final morphological changes. At the climax of metamorphosis, D2 expression is activated specifically in the anterior pituitary cells that express the genes for thyroid-stimulating hormone but not in the cells that express proopiomelanocortin.…”

mentioning

confidence: 99%

“…TH reaches a peak at the climax of metamorphosis and then falls as the final change, tail resorption, occurs (1,2). This gradual increase in TH concentration is essential for the sequential development of frog tissues and organs (3,4). The growth of the hind limbs is the earliest TH-induced morphological modification.…”

mentioning

confidence: 99%

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Timing of metamorphosis and the onset of the negative feedback loop between the thyroid gland and the pituitary is controlled by type II iodothyronine deiodinase in Xenopus laevis

Huang

Cai²,

Remo³

et al. 2001

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

100

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Two important features of amphibian metamorphosis are the sequential response of tissues to different concentrations of thyroid hormone (TH) and the development of the negative feedback loop between the pituitary and the thyroid gland that regulates TH synthesis by the thyroid gland. At the climax of metamorphosis in Xenopus laevis (when the TH level is highest), the ratio of the circulating precursor thyroxine (T 4) to the active form 3,5,3-triiodothyronine (T3) in the blood is many times higher than it is in tissues. This difference is because of the conversion of T 4 to T3 in target cells of the tadpole catalyzed by the enzyme type II iodothyronine deiodinase (D2) and the local effect (cell autonomy) of this activity. Limb buds and tails express D2 early and late in metamorphosis, respectively, correlating with the time that these organs undergo TH-induced change. T 3 is required to complete metamorphosis because the peak concentration of T 4 that is reached at metamorphic climax cannot induce the final morphological changes. At the climax of metamorphosis, D2 expression is activated specifically in the anterior pituitary cells that express the genes for thyroid-stimulating hormone but not in the cells that express proopiomelanocortin. Physiological concentrations of T 3 but not T4 can suppress thyrotropin subunit ␤ gene expression. The timing and the remarkable specificity of D2 expression in the thyrotrophs of the anterior pituitary coupled with the requirement for locally synthesized T3 strongly support a role for D2 in the onset of the negative feedback loop at the climax of metamorphosis. T he metamorphosis of anurans is controlled by a steadily increasing concentration of thyroid hormone (TH) in tadpoles. TH reaches a peak at the climax of metamorphosis and then falls as the final change, tail resorption, occurs (1, 2). This gradual increase in TH concentration is essential for the sequential development of frog tissues and organs (3, 4). The growth of the hind limbs is the earliest TH-induced morphological modification. In Xenopus laevis, the hind-limb buds form but cannot develop beyond Nieukoop Faber (NF) stage 53 (5) in the absence of TH. TH-induced growth and development of limbs occur when the endogenous TH concentration is low and is completed before the climax of metamorphosis (when TH concentration is the highest). Many metamorphic changes occur in rapid succession at climax. In about 4 days, the intestine remodels and the gills resorb followed by tail resorption, which takes another 3-4 days.A negative feedback loop between the thyroid gland, the pituitary, and the hypothalamus maintains the endogenous TH at a constant level in adults of higher vertebrates (6). The rising TH concentration in X. laevis tadpoles, which is so important for their sequential development, occurs paradoxically as the pituitary content of thyroid-stimulating hormone (TSH) mRNA is increasing also (7). Etkin (8) hypothesized that the rise in TH during the early part of tadpole development was caused by a positive feedba...

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Section: Growth Of Tadpoles On Inhibitors and Assays For Radioactive Andmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Timing of metamorphosis and the onset of the negative feedback loop between the thyroid gland and the pituitary is controlled by type II iodothyronine deiodinase in Xenopus laevis

Huang

Cai²,

Remo³

et al. 2001

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

100

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“…수온의 변화는 양서류의 수분투과성 피부에 영향을 미치며 동면기간, 개체의 발달, 에너지 대사, 생장, 면역시스템, 생식 등에 영향을 미친다 (Shoemaker et al, 1992;Dorcas et al, 2004;Cleland et al, 2006 (Carey and Bryant, 1995). Viparina and Just (1975) (Bachmann, 1969;Kuramoto and Tsuzuki, 1976;Berven et al, 1979;Hwang et al, 2014;Viparina and Just, 1975;Kollros, 1961;Fry, 1972) …”

Section: 특히 환경변화에 민감하게 반응하여 환경변화를 감지하 는 지표 종으로 잘 알려진 양서류는 수분투과성 피부를 unclassified

The effect of three different water temperatures in our research facility on Huanren brown frog (Rana huanrensis) egg's hatching rate, hatching periods, and larvae's growth

Na¹,

Shim²,

Kim³

et al. 2015

Journal of Wetlands Research

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This study was executed to know the effect of three differently controlled temperature conditions on Huanren brown frog (Rana huanrensis)'s growth in 2013. We've collected nine Huanren brown frog egg's sacs on Mt. Surak (37°40'55.86"N, 127°05'19.99"E) in Seoul. We put those nine egg sacs in the controlled growth chambers under low temperature (LT, 5 ± 2℃), medium temperature (MT, 10 ± 2℃), and high temperature (HT, 13 ± 2℃) conditions with three egg sacs, respectively. We measured the eggs' hatching rate, their hatching periods, and the size of the hatched individuals. The hatching rate was higher in MT (95.6%) and the rates of the other treatments were relatively lower but very similar such as LT (82.2%) and HT (82.6%). The three hatching periods were 10 days at HT, 14 days at MT and 23 days at LT. The body sizes of the hatched individuals were biggest at MT (7.62 ± 0.11㎜), smallest at LT (6.82 ± 0.10㎜) and medium at HT (7.19 ± 0.15㎜) (P-value ≤0.0001). From our results, we found that the various water temperatures could be very effective to Huanren brown frog eggs' hatch and growth including their body sizes. We suggest if we study more about the growth of Huanren brown adult frogs under similar temperature 1) †

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“…[28][29][30] Frog THs are structurally identical to mammalian THs, 30) while frog TH receptors (TRs) are highly homologous to other vertebrate counterparts. Type II deiodinase (DI-2) converts T 4 into the much more biologically active 3,3 ,5-triiodothyronine (T 3 ) through the removal of an outer ring iodine molecule, whereas type III deiodinase (DI-3) inactivates T 4 and T 3 by removal of an inner ring iodine molecule.…”

Section: Introductionmentioning

confidence: 99%

Disruption of Thyroid Hormone Function by Environmental Pollutants

Kashiwagi

Furuno

Kawa

et al. 2009

JOURNAL OF HEALTH SCIENCE

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A great number of synthetic chemicals are released into the environment, many of which are known or thought to interfere with normal thyroid hormone (TH) function. THs play important roles in regulating growth and development and maintaining metabolic homeostasis. For example, amphibian tadpole metamorphosis is a TH-triggered and controlled developmental process, and has proven to be useful as a screening tool for environmental pollutants suspected of disrupting TH functions. TH disruption is thought to be caused through a variety of mechanisms, including increased thyroxine (T 4 ) metabolism by uridine diphosphate glucuronyl transferases (UDPGTs), blocking TH signaling through TH receptors (TRs), and induction of mitochondrial membrane permeability transition (MPT). As our knowledge concerning the specific effects of these chemicals is very limited, further research is needed to obtain accurate information to be used in establishing guidelines for the protection of health in humans and wildlife.

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Mechanisms of Amphibian Metamorphosis: Hormones

Cited by 158 publications

References 17 publications

Timing of metamorphosis and the onset of the negative feedback loop between the thyroid gland and the pituitary is controlled by type II iodothyronine deiodinase in Xenopus laevis

Timing of metamorphosis and the onset of the negative feedback loop between the thyroid gland and the pituitary is controlled by type II iodothyronine deiodinase in Xenopus laevis

The effect of three different water temperatures in our research facility on Huanren brown frog (Rana huanrensis) egg's hatching rate, hatching periods, and larvae's growth

Disruption of Thyroid Hormone Function by Environmental Pollutants

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