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Evans EP, Helbing CC. Defining components of early thyroid hormone signalling through temperature-mediated activation of molecular memory in cultured Rana [lithobates] catesbeiana tadpole back skin. Gen Comp Endocrinol 2024; 347:114440. [PMID: 38159870 DOI: 10.1016/j.ygcen.2023.114440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/19/2023] [Accepted: 12/24/2023] [Indexed: 01/03/2024]
Abstract
Thyroid hormones (THs) are essential signalling molecules for the postembryonic development of all vertebrates. THs are necessary for the metamorphosis from tadpole to froglet and exogenous TH administration precociously induces metamorphosis. In American bullfrog (Rana [Lithobates] catesbeiana) tadpoles, the TH-induced metamorphosis observed at a warm temperature (24 °C) is arrested at a cold temperature (4 °C) even in the presence of exogenous THs. However, when TH-exposed tadpoles are shifted from cold to warm temperatures (4 → 24 °C), they undergo TH-dependent metamorphosis at an accelerated rate even when the initial TH signal is no longer present. Thus, they possess a "molecular memory" of TH exposure that establishes the TH-induced response program at the cold temperature and prompts accelerated metamorphosis after a shift to a warmer temperature. The components of the molecular memory that allow the uncoupling of initiation from the execution of the metamorphic program are not understood. To investigate this, we used cultured tadpole back skin (C-Skin) in a repeated measures experiment under 24 °C only, 4 °C only, and 4 → 24 °C temperature shifted regimes and reverse transcription quantitative polymerase chain reaction (RT-qPCR) and RNA-sequencing (RNA-seq) analyses. RNA-seq identified 570, 44, and 890 transcripts, respectively, that were significantly changed by TH treatment. These included transcripts encoding transcription factors and proteins involved in mRNA structure and stability. Notably, transcripts associated with molecular memory do not overlap with those identified previously in cultured tail fin (C-fin) except for TH-induced basic leucine zipper-containing protein (thibz) suggesting that thibz may have a central role in molecular memory that works with tissue-specific factors to establish TH-induced gene expression programs.
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Affiliation(s)
- E P Evans
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada
| | - C C Helbing
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada.
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2
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Aztekin C, Storer MA. To regenerate or not to regenerate: Vertebrate model organisms of regeneration-competency and -incompetency. Wound Repair Regen 2022; 30:623-635. [PMID: 35192230 PMCID: PMC7613846 DOI: 10.1111/wrr.13000] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/17/2022] [Accepted: 01/24/2022] [Indexed: 12/30/2022]
Abstract
Why only certain species can regenerate their appendages (e.g. tails and limbs) remains one of the biggest mysteries of nature. Unlike anuran tadpoles and salamanders, humans and other mammals cannot regenerate their limbs, but can only regrow lost digit tips under specific circumstances. Numerous hypotheses have been postulated to explain regeneration-incompetency in mammals. By studying model organisms that show varying regenerative abilities, we now have more opportunities to uncover what contributes to regeneration-incompetency and functionally test which perturbations restore appendage regrowth. Particularly, Xenopus laevis tail and limb, and mouse digit tip model systems exhibit naturally occurring variations in regenerative capacities. Here, we discuss major hypotheses that are suggested to contribute to regeneration-incompetency, and how species with varying regenerative abilities reflect on these hypotheses.
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Affiliation(s)
- Can Aztekin
- School of Life SciencesSwiss Federal Institute of Technology Lausanne (EPFL)Lausanne
| | - Mekayla A. Storer
- Department of Physiology, Development and Neuroscience and Wellcome‐MRC Cambridge Stem Cell InstituteUniversity of CambridgeCambridge
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3
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Wang H, Liu Y, Chai L, Wang H. Effects of nitrite exposure on metamorphosis and skeletal development of Bufo gargarizans. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:51847-51859. [PMID: 35253106 DOI: 10.1007/s11356-022-19468-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 02/23/2022] [Indexed: 06/14/2023]
Abstract
Nitrite, as a part of nitrogen cycle, is one of the most common toxic compounds in aquatic ecosystems. Since skeletal development is an essential process during amphibian metamorphosis, exposure of larval amphibians to nitrite might disrupt skeletal development. To evaluate whether nitrite affects skeletal development of amphibian larvae, Bufo gargarizans larvae at Gs26 were exposed to 10, 100, 500 and 1000 μg/L nitrite-nitrogen (NO2-N) in the present study. The metamorphosis rate, body weight, body length, forelimb length and hindlimb length of B. gargarizans exposed to NO2-N were decreased. The microscopic structures of thyroid gland were altered under NO2-N exposure at Gs42. The skeletal lengths of the humerus, femur and fibulare of tadpole at Gs42 were significantly reduced under 100, 500 and 1000 μg/L NO2-N treatment groups, and the lengths of humerus, tibia-fibula and tibiale of tadpole at Gs46 were significantly reduced under 1000 μg/L NO2-N treatment groups. In addition, the expression levels of thyroid hormone (TH) and endochondral ossification-related genes of tadpoles at Gs42 and Gs46 were tested by qRT-PCR. Overall, NO2-N exposure could affect the expressions of these genes and then may influence the activity and function of thyroid gland, further disturbing the amphibian metamorphosis and skeletal development of amphibian larvae.
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Affiliation(s)
- Hemei Wang
- College of Life Science, Shaanxi Normal University, Xi'an 710119, China
| | - Yutian Liu
- College of Life Science, Shaanxi Normal University, Xi'an 710119, China
| | - Lihong Chai
- School of Water and Environment, Chang'an University, Xi'an 710054, China
- Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, Chang'an University, Xi'an, 710062, China
| | - Hongyuan Wang
- College of Life Science, Shaanxi Normal University, Xi'an 710119, China.
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4
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Vassilieva AB, Smirnov SV. Increasing Hormonal Control of Skeletal Development: An Evolutionary Trend in Amphibians. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.733947] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The biphasic life history of amphibians includes metamorphosis, a complex developmental event that involves drastic changes in the morphology, physiology and biochemistry accompanying the transition from the larval to adult stage of development. Thyroid hormones (THs) are widely known to orchestrate this remodeling and, in particular, to mediate the development of the bony skeleton, which is a model system in evolutionary morphological studies of amphibians. Detailed experimental studies of the role of THs in the craniogenesis of diverse urodelan amphibians revealed that (i) these hormones affect both the timing and sequence of bone formation, (ii) TH involvement increases in parallel with the increase in divergence between larval and adult skull morphology, and (iii) among urodelans, TH-involvement in skull development changes from a minimum in basal salamanders (Hynobiidae) to the most pronounced in derived ones (Salamandridae and Plethodontidae). Given the increasing regulatory function of THs in urodelan evolution, we hypothesized a stronger involvement of THs in the control of skeletogenesis in anurans with their most complex and dramatic metamorphosis among all amphibians. Our experimental study of skeletal development in the hypo- and hyperthyroid yellow-bellied toad (Bombina variegata: Bombinatoridae) supports the greater involvement of THs in the mediation of all stages of anuran cranial and postcranial bones formation. Similar to urodelans, B. variegata displays enhancing TH involvement in the development of cranial bones that arise during larval ontogeny: while the hormonal impact on early larval ossifications is minimal, the skull bones forming during metamorphosis are strictly TH-inducible. However, in contrast to urodelans, all cranial bones, including the earliest to form, are TH-dependent in B. variegata; moreover, the development of all elements of the axial and limb skeleton is affected by THs. The more accentuated hormonal control of skeletogenesis in B. variegata demonstrates the advanced regulatory and inductive function of THs in the orchestration of anuran metamorphosis. Based on these findings, we discuss (i) changes in THs function in amphibian evolution and (ii) the role of THs in the evolution of life histories in amphibians.
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Transcriptome and Methylome Analysis Reveal Complex Cross-Talks between Thyroid Hormone and Glucocorticoid Signaling at Xenopus Metamorphosis. Cells 2021; 10:cells10092375. [PMID: 34572025 PMCID: PMC8468809 DOI: 10.3390/cells10092375] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/31/2021] [Accepted: 09/03/2021] [Indexed: 12/29/2022] Open
Abstract
Background: Most work in endocrinology focus on the action of a single hormone, and very little on the cross-talks between two hormones. Here we characterize the nature of interactions between thyroid hormone and glucocorticoid signaling during Xenopus tropicalis metamorphosis. Methods: We used functional genomics to derive genome wide profiles of methylated DNA and measured changes of gene expression after hormonal treatments of a highly responsive tissue, tailfin. Clustering classified the data into four types of biological responses, and biological networks were modeled by system biology. Results: We found that gene expression is mostly regulated by either T3 or CORT, or their additive effect when they both regulate the same genes. A small but non-negligible fraction of genes (12%) displayed non-trivial regulations indicative of complex interactions between the signaling pathways. Strikingly, DNA methylation changes display the opposite and are dominated by cross-talks. Conclusion: Cross-talks between thyroid hormones and glucocorticoids are more complex than initially envisioned and are not limited to the simple addition of their individual effects, a statement that can be summarized with the pseudo-equation: TH ∙ GC > TH + GC. DNA methylation changes are highly dynamic and buffered from genome expression.
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Janes TA, Rousseau JP, Fournier S, Kiernan EA, Harris MB, Taylor BE, Kinkead R. Development of central respiratory control in anurans: The role of neurochemicals in the emergence of air-breathing and the hypoxic response. Respir Physiol Neurobiol 2019; 270:103266. [PMID: 31408738 PMCID: PMC7476778 DOI: 10.1016/j.resp.2019.103266] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/10/2019] [Accepted: 08/05/2019] [Indexed: 01/08/2023]
Abstract
Physiological and environmental factors impacting respiratory homeostasis vary throughout the course of an animal's lifespan from embryo to adult and can shape respiratory development. The developmental emergence of complex neural networks for aerial breathing dates back to ancestral vertebrates, and represents the most important process for respiratory development in extant taxa ranging from fish to mammals. While substantial progress has been made towards elucidating the anatomical and physiological underpinnings of functional respiratory control networks for air-breathing, much less is known about the mechanisms establishing these networks during early neurodevelopment. This is especially true of the complex neurochemical ensembles key to the development of air-breathing. One approach to this issue has been to utilize comparative models such as anuran amphibians, which offer a unique perspective into early neurodevelopment. Here, we review the developmental emergence of respiratory behaviours in anuran amphibians with emphasis on contributions of neurochemicals to this process and highlight opportunities for future research.
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Affiliation(s)
- Tara A Janes
- Department of Pediatrics, Université Laval & Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC, Canada
| | - Jean-Philippe Rousseau
- Department of Pediatrics, Université Laval & Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC, Canada
| | - Stéphanie Fournier
- Department of Pediatrics, Université Laval & Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC, Canada
| | - Elizabeth A Kiernan
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison Wisconsin, USA
| | - Michael B Harris
- Department of Biological Sciences, California State University Long Beach, California, USA
| | - Barbara E Taylor
- Department of Biological Sciences, California State University Long Beach, California, USA
| | - Richard Kinkead
- Department of Pediatrics, Université Laval & Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC, Canada.
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Ruchin AB. The effect of illumination and light spectrum on growth and larvae development of Pelophylax ridibundus (Amphibia: Anura). BIOL RHYTHM RES 2019. [DOI: 10.1080/09291016.2019.1594126] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Alexander B. Ruchin
- Science Department, Joint Directorate of Mordovia State Nature Reserve and Smolny National Park, Saransk, Russia
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8
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Xie L, Li XY, Liang K, Wu C, Wang HY, Zhang YH. Octylphenol influence growth and development of Rana chensinensis tadpoles via disrupting thyroid function. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 169:747-755. [PMID: 30502525 DOI: 10.1016/j.ecoenv.2018.11.083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 11/15/2018] [Accepted: 11/19/2018] [Indexed: 05/20/2023]
Abstract
Octylphenol (OP), a class of endocrine disrupting chemicals (EDCs), could produce adverse effects on developmental process of animals. Thyroid hormone is one of the important hormones involved in animal development. To determine whether OP affect the growth and development of amphibian larvae via interfering the thyroid function, Rana chensinensis larvae at Gosner stage 29 were exposed to 10-8, 10-7 and 10-6 mol/L OP in the present study. Results demonstrated that OP could decrease the body length and mass and retard the development of tadpoles. The histologic evaluation showed microscopic structures of thyroid gland were changed in 10-7 and 10-6 mol/L OP treated groups on day 40. The expression levels of Dio2, Dio3, TRα and TRβ mRNA in the liver, brain, skin and tail of tadpoles were detected by qRT-PCR, when treated with OP for 20, 30, 40 and 50 day, respectively. The results of qRT-PCR showed OP could affect the expressions of Dio2, Dio3, TRα and TRβ mRNA in the four tissues, and then influence the activity and function of THs, further affecting the growth and development of the tadpoles.
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Affiliation(s)
- Lei Xie
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, Shaanxi, PR China
| | - Xin-Yi Li
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, Shaanxi, PR China
| | - Kai Liang
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, Shaanxi, PR China
| | - Chao Wu
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, Shaanxi, PR China
| | - Hong-Yuan Wang
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, Shaanxi, PR China
| | - Yu-Hui Zhang
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, Shaanxi, PR China.
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9
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Liu L, Zhu W, Liu J, Wang S, Jiang J. Identification and differential regulation of microRNAs during thyroid hormone-dependent metamorphosis in Microhyla fissipes. BMC Genomics 2018; 19:507. [PMID: 29954327 PMCID: PMC6025837 DOI: 10.1186/s12864-018-4848-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 05/31/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Anuran metamorphosis, which is obligatorily initiated and sustained by thyroid hormone (TH), is a dramatic example of extensive morphological, biochemical and cellular changes occurring during post-embryonic development. Thus, it provides an ideal model to understand the actions of the hormone and molecular mechanisms underlying these developmental and apoptotic processes. In addition to transcriptional factors, microRNAs (miRNAs) play key roles in diverse biological processes via post-transcriptional repression of mRNAs. However, the possible role of miRNAs in anuran metamorphosis is not well understood. Screening and identification of TH-responding miRNAs are required to reveal the integrated regulatory mechanisms of TH during metamorphosis. Given the specific role of TRs during M. fissipes metamorphosis and the characteristics of M. fissipes as an ideal model, Illumina sequencing technology was employed to get a full scope of miRNA in M. fissipes metamorphosis treated by T3. RESULTS Morphological and histological analysis revealed that 24 h T3 treatment M. fissipes tadpoles resembled that at the climax of natural metamorphosis. Thus, small RNA libraries were constructed from control and 24 h T3 treatment groups. A total of 164 conserved miRNAs and 36 predicted novel miRNAs were characterized. Furthermore, 5' first and ninth nucleotides of miRNAs were significantly enriched in U in our study. In all, 21 miRNAs were differentially expressed between the T3 and control groups (p < 0.01). A total of 10,206 unigenes were identified as target genes of these differentially expressed miRNAs. KEGG pathway analysis indicated that the most overrepresented miRNA target genes were enriched in the "PI3k-Akt signaling pathway". In addition, a network associated with the TH signaling pathway provides an opportunity to further understand the complex biological processes that occur in metamorphosis. CONCLUSIONS We identified a large number of miRNAs during M. fissipes metamorphosis, and 21 of them were differentially expressed in the two groups that represented two different metamorphic stages. These miRNAs may play important roles during metamorphosis. The study gives us clues for further studies of the mechanisms of anuran metamorphosis and provides a model to study the mechanism of TH-affected biological processes in humans.
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Affiliation(s)
- Lusha Liu
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041 China
| | - Wei Zhu
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041 China
| | - Jiongyu Liu
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041 China
| | - Shouhong Wang
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Jianping Jiang
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041 China
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Phatarphekar A, Su Q, Eun SH, Chen X, Rokita SE. The importance of a halotyrosine dehalogenase for Drosophila fertility. J Biol Chem 2018; 293:10314-10321. [PMID: 29764939 DOI: 10.1074/jbc.ra118.003364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 05/11/2018] [Indexed: 12/18/2022] Open
Abstract
The ability of iodotyrosine deiodinase to salvage iodide from iodotyrosine has long been recognized as critical for iodide homeostasis and proper thyroid function in vertebrates. The significance of its additional ability to dehalogenate bromo- and chlorotyrosine is less apparent, and none of these functions could have been anticipated in invertebrates until recently. Drosophila, as most arthropods, contains a deiodinase homolog encoded by CG6279, now named condet (cdt), with a similar catalytic specificity. However, its physiological role cannot be equivalent because Drosophila lacks a thyroid and its associated hormones, and no requirement for iodide or halotyrosines has been reported for this species. We have now applied CRISPR/Cas9 technology to generate Drosophila strains in which the cdt gene has been either deleted or mutated to identify its biological function. As previously shown in larvae, expression of cdt is primarily limited to the fat body, and we now report that loss of cdt function does not enhance sensitivity of the larvae to the toxic effects of iodotyrosine. In adult flies by contrast, expression is known to occur in testes and is detected at very high levels in this tissue. The importance of cdt is most evident in the decrease in fertility observed when either males or females carry a deletion or mutation of cdt Therefore, dehalogenation of a halotyrosine appears essential for efficient reproduction in Drosophila and likely contributes to a new pathway for controlling viability in arthropods.
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Affiliation(s)
| | - Qi Su
- From the Departments of Chemistry and
| | - Suk Ho Eun
- Biology, Johns Hopkins University, Baltimore, Maryland 21218
| | - Xin Chen
- Biology, Johns Hopkins University, Baltimore, Maryland 21218
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Sakane Y, Iida M, Hasebe T, Fujii S, Buchholz DR, Ishizuya-Oka A, Yamamoto T, Suzuki KIT. Functional analysis of thyroid hormone receptor beta in Xenopus tropicalis founders using CRISPR-Cas. Biol Open 2018; 7:bio.030338. [PMID: 29358165 PMCID: PMC5829506 DOI: 10.1242/bio.030338] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Amphibians provide an ideal model to study the actions of thyroid hormone (TH) in animal development because TH signaling via two TH receptors, TRα and TRβ, is indispensable for amphibian metamorphosis. However, specific roles for the TRβ isoform in metamorphosis are poorly understood. To address this issue, we generated trβ-disrupted Xenopus tropicalis tadpoles using the CRISPR-Cas system. We first established a highly efficient and rapid workflow for gene disruption in the founder generation (F0) by injecting sgRNA and Cas9 ribonucleoprotein. Most embryos showed severe mutant phenotypes carrying high somatic mutation rates. Utilizing this founder analysis system, we examined the role of trβ in metamorphosis. trβ-disrupted pre-metamorphic tadpoles exhibited mixed responsiveness to exogenous TH. Specifically, gill resorption and activation of several TH-response genes, including trβ itself and two protease genes, were impaired. However, hind limb outgrowth and induction of the TH-response genes, klf9 and fra-2, were not affected by loss of trβ Surprisingly, trβ-disrupted tadpoles were able to undergo spontaneous metamorphosis normally, except for a slight delay in tail resorption. These results indicate TRβ is not required but contributes to the timing of resorptive events of metamorphosis.
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Affiliation(s)
- Yuto Sakane
- Department of Mathematical and Life Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Midori Iida
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Fukuoka 820-8502, Japan
| | - Takashi Hasebe
- Department of Biology, Nippon Medical School, Musashino, Tokyo 180-0023, Japan
| | - Satoshi Fujii
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Fukuoka 820-8502, Japan
| | - Daniel R Buchholz
- Department of Biological Sciences, University of Cincinnati, 312 Clifton Ct., Cincinnati, OH, 45221, USA
| | - Atsuko Ishizuya-Oka
- Department of Biology, Nippon Medical School, Musashino, Tokyo 180-0023, Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Ken-Ichi T Suzuki
- Department of Mathematical and Life Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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12
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Cheng C, Di S, Chen L, Zhang W, Diao J, Zhou Z. Enantioselective Bioaccumulation, Tissue Distribution, and Toxic Effects of Myclobutanil Enantiomers in Pelophylax nigromaculatus Tadpole. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2017; 65:3096-3102. [PMID: 28291946 DOI: 10.1021/acs.jafc.7b00086] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Research on the enantioselective behavior of chiral pesticides on amphibians has received growing attention, because amphibians are experiencing a population decline and amphibian metamorphosis shares many similarities with human fetal development. In this study, the enantioselective behavior of myclobutanil on Pelophylax nigromaculatus tadpole was studied. The antioxidant enzyme (SOD, GST) activities and malondialdehyde (MDA) content were investigated to assess the different toxic effects when tadpoles were exposed to myclobutanil enantiomers for 96 h. In the chronic exposure experiment, the bioaccumulation concentration of (-)-myclobutanil in tadpoles is significantly higher than that of (+)-myclobutanil, and the concentration of myclobutanil in tadpole intestine and liver was higher compared with other tissues. During the elimination experiment, about 95% of myclobutanil in tadpoles was eliminated within only 24 h. On the basis of these data, the enantiomeric differences should be taken into consideration in the risk assessment of myclobutanil.
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Affiliation(s)
- Cheng Cheng
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University , Yuanmingyuan West Road 2, Beijing 100193, China
| | - Shanshan Di
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University , Yuanmingyuan West Road 2, Beijing 100193, China
| | - Li Chen
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University , Yuanmingyuan West Road 2, Beijing 100193, China
| | - Wenjun Zhang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University , Yuanmingyuan West Road 2, Beijing 100193, China
| | - Jinling Diao
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University , Yuanmingyuan West Road 2, Beijing 100193, China
| | - Zhiqiang Zhou
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University , Yuanmingyuan West Road 2, Beijing 100193, China
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13
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Zhao L, Liu L, Wang S, Wang H, Jiang J. Transcriptome profiles of metamorphosis in the ornamented pygmy frog Microhyla fissipes clarify the functions of thyroid hormone receptors in metamorphosis. Sci Rep 2016; 6:27310. [PMID: 27254593 PMCID: PMC4890586 DOI: 10.1038/srep27310] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 05/16/2016] [Indexed: 11/09/2022] Open
Abstract
Anuran metamorphosis is an excellent system in which to study postembryonic development. Studies on Xenopus (Mesobatrachia) show that thyroid hormone receptors (TRs) regulate metamorphosis in a ligand-dependent manner by coordinating the action of hundreds of genes. However, whether this mechanism is conserved among amphibians is still unknown. To understand the molecular mechanism of this universal phenomenon, we report the transcriptional profiles of the three key developmental stages in Microhyla fissipes (Neobatrachia): premetamorphosis (PM), metamorphic climax (MC) and completion of metamorphosis (CM). In total, 2,293 differentially expressed genes were identified from comparisons of transcriptomes, and these genes showed stage-specific expression patterns. Unexpectedly, we found that TRα was highly expressed in Xenopus laevis and Bufo gargarizans at premetamorphosis but showed low expression in M. fissipes. In contrast, TRβ was highly expressed during metamorphosis in M. fissipes and X. laevis. This result may imply that TRβ is essential for initiating metamorphosis, at least in M. fissipes. Thus, our work not only identifies genes that are likely to be involved in Neobatrachia metamorphosis but also clarifies the roles of unliganded TRα in regulating tadpole growth and timing of metamorphosis, which may be conserved in anurans, and the role of liganded TRβ in launching metamorphosis.
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Affiliation(s)
- Lanying Zhao
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lusha Liu
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Shouhong Wang
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongyuan Wang
- College of Life Sciences, Shaanxi Normal University, Xi'an 710062, China
| | - Jianping Jiang
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
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Li S, Li M, Wang Q, Gui W, Zhu G. Exposure to butachlor causes thyroid endocrine disruption and promotion of metamorphosis in Xenopus laevis. CHEMOSPHERE 2016; 152:158-165. [PMID: 26971167 DOI: 10.1016/j.chemosphere.2016.02.098] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 02/22/2016] [Accepted: 02/23/2016] [Indexed: 06/05/2023]
Abstract
Butachlor is extensively applied in rice paddy ecosystem in china, and has been widespread contaminant in the aquatic environment. Here, Xenopus laevis was used for the evaluation of teratogenesis developmental toxicity, and disruption of thyroid system when exposure to different concentrations of butachlor by window phase exposure. Acute toxicity investigation shown that 96 h-LC50 value of butachlor was 1.424 mg L(-1) and 0.962 mg L(-1) for tadpoles (starting from stages 46/47) and embryos (starting from stages 8/9), respectively. Exposure to butachlor caused malformation, including abnormal eye, pericardial edema, enlarged proctodaeum and bent tail. Window phase exposure test indicated that butachlor significantly promote the contents of whole-body thyroid hormones (THs, T3 and T4) at higher levels, indicating thyroid endocrine disruption. At 7 days, exposure to butachlor up-regulated the mRNA expression of genes involved in THs synthesis and metabolism (tshα, tg, tpo and dio1) and THs receptors (trα and trβ). At 14 days, up-regulation of the mRNA expression of genes related to THs synthesis and metabolism (tshα, tshβ, tg, tpo, dio1, dio2 and ttr) and THs receptors (trβ) were also observed after the exposure to butachlor. At 21 days, butachlor up-regulated the mRNA expression of tshα, tg, tpo genes and down-regulated the mRNA expression of tshβ, tg, dio1, ttr and trα genes. These results showed that butachlor could change the mRNA expression of genes involved in the HPT axis and increase whole-body thyroid hormones levels of X. laevis tadpoles in a dose- and time-dependent manner, causing thyroid endocrine disruption and developmental toxicity.
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Affiliation(s)
- Shuying Li
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, 310058, PR China
| | - Meng Li
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, 310058, PR China
| | - Qiangwei Wang
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, 310058, PR China
| | - Wenjun Gui
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, 310058, PR China
| | - Guonian Zhu
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, 310058, PR China.
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15
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Li M, Cao C, Li S, Gui W, Zhu G. Thyroid endocrine disruption of azocyclotin to Xenopus laevis during metamorphosis. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2016; 43:61-67. [PMID: 26970056 DOI: 10.1016/j.etap.2016.02.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 02/20/2016] [Accepted: 02/22/2016] [Indexed: 06/05/2023]
Abstract
Organotin compounds are ubiquitous contaminants that are frequently detected in the environment and in biota, which raises concern about their risk to wildlife and human health. In the present study, Nieuwkoop & Faber stage 51 Xenopus laevis tadpoles were exposed to different concentrations of azocyclotin (0, 0.02, 0.1 and 0.5μg/L) for 21 days, during which time the tadpoles underwent morphological development. Exposure to azocyclotin caused an inhibitory effect on the pre-metamorphic development of X. laevis (e.g., a shortened hind limb length). Azocyclotin induced an alteration of the triiodothyronine (T3) content, which indicated thyroid endocrine disruption. Real-time PCR was performed to examine the expression levels of the genes involved in the thyroid hormone (TH) signaling pathway. Significant down-regulation of the type 2 deiodinase gene was observed, which may be partially responsible for the decreased T3 concentrations. Furthermore, the expression of T3 responsive genes, including thyroid hormone receptor, basic transcription element binding protein, 2tromelysins-3 and matrix metalloproteinase 2, were down-regulated in tadpoles, suggesting that azocyclotin induced a decrease in the T3 contents and, in turn, affected the mRNA expression of downstream genes involved in multiple physiological responses. Chemical analysis showed that azocyclotin could accumulate in X. laevis after 21 days of exposure. In conclusion, the results of the present study showed that azocyclotin could alter the mRNA expression of genes involved in TH signaling as well as the thyroid hormone concentrations in X. laevis tadpoles, leading to endocrine disruption of thyroid system, and that azocyclotin had obvious inhibitory effects on X. laevis metamorphosis.
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Affiliation(s)
- Meng Li
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China
| | - Chuyan Cao
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China
| | - Shuying Li
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China
| | - Wenjun Gui
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China.
| | - Guonian Zhu
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310058, PR China
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16
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Niu D, Wang F, Xie S, Sun F, Wang Z, Peng M, Li J. Developmental Transcriptome Analysis and Identification of Genes Involved in Larval Metamorphosis of the Razor Clam, Sinonovacula constricta. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2016; 18:168-175. [PMID: 26921240 DOI: 10.1007/s10126-016-9691-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 01/13/2016] [Indexed: 06/05/2023]
Abstract
The razor clam Sinonovacula constricta is an important commercial species. The deficiency of developmental transcriptomic data is becoming the bottleneck of further researches on the mechanisms underlying settlement and metamorphosis in early development. In this study, de novo transcriptome sequencing was performed for S. constricta at different early developmental stages by using Illumina HiSeq 2000 paired-end (PE) sequencing technology. A total of 112,209,077 PE clean reads were generated. De novo assembly generated 249,795 contigs with an average length of 585 bp. Gene annotation resulted in the identification of 22,870 unigene hits against the NCBI database. Eight unique sequences related to metamorphosis were identified and analyzed using real-time PCR. The razor clam reference transcriptome would provide useful information on early developmental and metamorphosis mechanisms and could be used in the genetic breeding of shellfish.
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Affiliation(s)
- Donghong Niu
- Shanghai Engineering Research Center of Aquaculture and College of Fisheries and Life Science, Shanghai Ocean University, 999 Hucheng Huan Road, Shanghai, 201306, China
| | - Fei Wang
- Shanghai Engineering Research Center of Aquaculture and College of Fisheries and Life Science, Shanghai Ocean University, 999 Hucheng Huan Road, Shanghai, 201306, China
| | - Shumei Xie
- Shanghai Engineering Research Center of Aquaculture and College of Fisheries and Life Science, Shanghai Ocean University, 999 Hucheng Huan Road, Shanghai, 201306, China
| | - Fanyue Sun
- Department of Reconstructive Sciences, Center for Regenerative Medicine and Developmental Biology, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Ze Wang
- Shanghai Engineering Research Center of Aquaculture and College of Fisheries and Life Science, Shanghai Ocean University, 999 Hucheng Huan Road, Shanghai, 201306, China
| | - Maoxiao Peng
- Shanghai Engineering Research Center of Aquaculture and College of Fisheries and Life Science, Shanghai Ocean University, 999 Hucheng Huan Road, Shanghai, 201306, China
| | - Jiale Li
- Shanghai Engineering Research Center of Aquaculture and College of Fisheries and Life Science, Shanghai Ocean University, 999 Hucheng Huan Road, Shanghai, 201306, China.
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17
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Orton F, Tyler CR. Do hormone-modulating chemicals impact on reproduction and development of wild amphibians? Biol Rev Camb Philos Soc 2014; 90:1100-17. [DOI: 10.1111/brv.12147] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 09/01/2014] [Accepted: 09/12/2014] [Indexed: 01/17/2023]
Affiliation(s)
- Frances Orton
- Biosciences; College of Life and Environmental Sciences, University of Exeter; Stocker Road Exeter EX4 4QD U.K
| | - Charles R. Tyler
- Biosciences; College of Life and Environmental Sciences, University of Exeter; Stocker Road Exeter EX4 4QD U.K
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18
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Zhang YF, Xu W, Lou QQ, Li YY, Zhao YX, Wei WJ, Qin ZF, Wang HL, Li JZ. Tetrabromobisphenol A disrupts vertebrate development via thyroid hormone signaling pathway in a developmental stage-dependent manner. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:8227-34. [PMID: 24963557 DOI: 10.1021/es502366g] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Data concerning effects of tetrabromobisphenol A (TBBPA) on thyroid hormone (TH)-dependent vertebrate development have been limited, although TBBPA has been demonstrated in vitro to disrupt the TH signaling pathway at the transcriptional level. In this study, we investigated the effects of TBBPA on T3-induced and spontaneous Xenopus laevis metamorphosis, which share many similarities with TH-dependent development in higher vertebrates. In a 6-day T3-induced metamorphosis assay using premetamorphic tadpoles, 10-1000 nM TBBPA exhibited inhibitory effects on T3-induced expression of TH-response genes and morphological changes in a concentration-dependent manner, with a weak stimulatory action on tadpole development and TH-response gene expression in the absence of T3 induction. In a spontaneous metamorphosis assay, we further found that TBBPA promoted tadpole development from stage 51 to 56 (pre- and prometamorphic stages) but inhibited metamorphic development from stage 57 to 66 (metamorphic climax). These results strongly show that TBBPA, even at low concentrations, disrupts TH-dependent development in a developmental stage-dependent manner, i.e., TBBPA exhibits an antagonistic activity at the developmental stages when animals have high endogenous TH levels, whereas it acts as an agonist at the developmental stages when animals have low endogenous TH levels. Our study highlights the adverse influences of TBBPA on TH-dependent development in vertebrates.
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Affiliation(s)
- Yin-Feng Zhang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-environmental Sciences and ‡Department of Environmental Bio-Technology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences , P.O. Box 2871, Beijing 100085, China
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19
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Heijlen M, Houbrechts AM, Bagci E, Van Herck SLJ, Kersseboom S, Esguerra CV, Blust R, Visser TJ, Knapen D, Darras VM. Knockdown of type 3 iodothyronine deiodinase severely perturbs both embryonic and early larval development in zebrafish. Endocrinology 2014; 155:1547-59. [PMID: 24467742 DOI: 10.1210/en.2013-1660] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Exposure to appropriate levels of thyroid hormones (THs) at the right time is of key importance for normal development in all vertebrates. Type 3 iodothyronine deiodinase (D3) is the prime TH-inactivating enzyme, and its expression is highest in the early stages of vertebrate development, implying that it may be necessary to shield developing tissues from overexposure to THs. We used antisense morpholino knockdown to examine the role of D3 during early development in zebrafish. Zebrafish possess 2 D3 genes, dio3a and dio3b. Here, we show that both genes are expressed during development and both contribute to in vivo D3 activity. However, dio3b mRNA levels in embryos are higher, and the effects of dio3b knockdown on D3 activity and on the resulting phenotype are more severe. D3 knockdown induced an overall delay in development, as determined by measurements of otic vesicle length, eye and ear size, and body length. The time of hatching was also severely delayed in D3-knockdown embryos. Importantly, we also observed a severe disturbance of several aspects of development. Swim bladder development and inflation was aberrant as was the development of liver and intestine. Furthermore, D3-knockdown larvae spent significantly less time moving, and both embryos and larvae exhibited perturbed escape responses, suggesting that D3 knockdown affects muscle development and/or functioning. These data indicate that D3 is essential for normal zebrafish embryonic and early larval development and show the value of morpholino knockdown in this model to further elucidate the specific role of D3 in some aspects of vertebrate development.
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Affiliation(s)
- Marjolein Heijlen
- Laboratory of Comparative Endocrinology (M.H., A.M.H., S.L.J.V.H., V.M.D.), Department of Biology, Division of Animal Physiology and Neurobiology, and Laboratory for Molecular Biodiscovery (C.V.E.), Department of Pharmaceutical and Pharmacological Sciences, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium; Systemic Physiological and Ecotoxicological Research (E.B., R.B., D.K.), Department of Biology, and Zebrafishlab (D.K.), Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Belgium; and University of Antwerp, 2610 Wilrijk, Belgium; Department of Internal Medicine (S.K., T.J.V.), Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
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20
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Guedes J, Carrasco S, Ferreira C, Bonamin L, Souza W, Goldenstein-Schainberg C, Parra E, Capelozzi V. Ultra High Dilution of triiodothyronine modifies cellular apoptosis in Rana catesbeiana tadpole tail in vitro. HOMEOPATHY 2011; 100:220-7. [DOI: 10.1016/j.homp.2011.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 04/27/2011] [Accepted: 05/06/2011] [Indexed: 11/26/2022]
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21
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Shi ZY, Chen XW, Gu YF. Cloning and expression pattern of alkaline phosphatase during the development of Paralichthys olivaceus. FISH PHYSIOLOGY AND BIOCHEMISTRY 2011; 37:411-424. [PMID: 20922565 DOI: 10.1007/s10695-010-9441-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Accepted: 09/20/2010] [Indexed: 05/29/2023]
Abstract
Alkaline phosphatases are ubiquitous enzymes involved in many important biological processes. Mammalian tissue-nonspecific alkaline phosphatase has long been thought to feature in embryonic development and bone formation. In this study, an alkaline phosphatase (ALP) gene from Paralichthys olivaceus was identified by rapid amplification of cDNA ends and genome-walking PCR. The ALP gene extends 10,141 bp and contains 11 exons and 10 introns. The open reading frame of the ALP transcript consists of 1,431 bp, which encodes 476 amino acids products named as POALP. An analysis of its secondary and tertiary structure revealed that the POALP was conserved in different species, but one disulfide linkage made it possible to adapt to low-temperature environment. The ALP activity was found to be first detectable in the embryo before hatching. The POALP was distributed ubiquitously in the body of P. olivaceus and was particularly high in the digestive tract. These findings suggest the potential role of POALP in nutrient absorption and transportation. During the pre-metamorphosis (F stage), ALP gene expression is 2.5-folds of that in the pro-metamorphosis (E stage); but in the post-metamorphosis (I stage), it was 1.8-folds of that of pro-metamorphosis. Exogenetic thyroxine (T4) and thiourea (TU) influenced the ALP gene expression significantly during the metamorphosis. Bioinformatics analysis showed that Japanese flounder ALP promoter region contained promoter sequence and putative recognition site for several transcriptional factors, including SREBP-1, SYR, and CdxA. In vitro promoter assays employing EGFP reporter system demonstrated that the promoter of ALP was active.
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Affiliation(s)
- Z Y Shi
- College of Fisheries and Life Science, Shanghai Ocean University, 201306 Shanghai, China.
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22
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Davidson MA, Croteau MC, Millar CS, Trudeau VL, Lean DRS. Fate and developmental effects of dietary uptake of methylmercury in Silurana tropicalis tadpoles. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2011; 74:364-379. [PMID: 21271437 DOI: 10.1080/15287394.2011.534427] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Adverse effects of methylmercury (MeHg) exposure during amphibian metamorphosis remain to be fully characterized. Most previous investigations determined effects of short-term exposure to elevated dose rates, without information on mercury (Hg) depuration and degradation pathways. Since metamorphosis is primarily controlled by thyroid hormones (TH), alterations in this process suggest a disruption of the TH endocrine axis. The aim of this research was to (1) characterize patterns of MeHg accumulation and depuration in tadpoles and (2) examine effects of MeHg accumulation on metamorphosis and the TH axis. Silurana tropicalis tadpoles were exposed to environmental levels of dietary MeHg until metamorphic climax. Whole-body MeHg and total Hg (THg) levels were measured, as well as the number of metamorphs, rate of metamorphosis, body size, and whole-body triiodothyronine (T3) levels at metamorphosis. Tadpoles exposed to a higher level of MeHg exhibited increased mortality and size, and reduced metamorphosis. At lower levels of MeHg, body burdens increased rapidly and eventually reached a plateau, whereas no plateau was reached at a higher level of MeHg exposure. T3 levels were not affected. Data indicate that at low and medium levels of exposure, depuration of MeHg may prevent toxicity in tadpoles. However, depuration mechanisms may be insufficient at high doses, producing disruption of metamorphosis and death. Although there were no marked effects of MeHg on whole-body T3 levels, further investigation of other components of the TH axis is warranted.
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Affiliation(s)
- Melissa A Davidson
- Centre for Advanced Research in Environmental Genomics (CAREG), Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
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23
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Croteau MC, Duarte-Guterman P, Lean DRS, Trudeau VL. Preexposure to ultraviolet B radiation and 4-tert-octylphenol affects the response of Rana pipiens tadpoles to 3,5,3'-triiodothyronine. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2010; 29:1804-1815. [PMID: 20821635 DOI: 10.1002/etc.232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Exposure to multiple environmental stressors is negatively impacting the health of amphibians worldwide. Increased exposure to ultraviolet B radiation (UVBR) and chemical pollutants may affect amphibian populations by disrupting metamorphosis; however, the actual mechanisms by which these stressors affect development remain unknown. Because amphibian metamorphosis is controlled by thyroid hormones (TH), changes in developmental rates by environmental stress suggest a disruption of the thyroid system. Tadpoles were chronically exposed to environmental levels of UVBR (average of 0.15 W/m2) and 4-tert-octylphenol (OP; 10 nM), alone and combined, prior to being challenged to exogenous TH triiodothyronine (T3; 5 or 50 nM). This experimental approach was taken to determine whether exposure to these stressors affects the ability of T3 to elicit specific molecular and morphological responses. Exposure to OP increased mRNA levels of thyroid receptors (TRs) alpha and beta, deiodinase type 2 (D2), and corticotropin releasing hormone in the brain and of D2 in the tail of tadpoles. 4-tert-octylphenol also enhanced T3-induced expression of D2 in the brain. The combination of UVBR and OP affected the expression of TR alpha in the brain and the responses of TR alpha and beta genes to T3 in the tail, demonstrating the importance of considering the effects of multiple stressors on amphibians. Tadpoles exposed to UVBR were developmentally delayed and exhibited slowed tail resorption and accelerated hindlimb development following exposure to T3. Together, these findings indicate that UVBR alters the rate of development and TH-dependent morphological changes at metamorphosis, and that exposure to UVBR and/or OP disrupts the expression of genes important for development and the biological action of T3 in peripheral tissues. Our group is the first to demonstrate that environmental levels of UVBR and/or OP can affect the thyroid system of amphibians.
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Affiliation(s)
- Maxine C Croteau
- Centre for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, 20 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.
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24
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An KW, An MI, Nelson ER, Habibi HR, Choi CY. Gender-related expression of TRalpha and TRbeta in the protandrous black porgy, Acanthopagrus schlegeli, during sex change processes. Gen Comp Endocrinol 2010; 165:11-8. [PMID: 19481082 DOI: 10.1016/j.ygcen.2009.05.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Revised: 05/21/2009] [Accepted: 05/21/2009] [Indexed: 10/20/2022]
Abstract
We cloned the thyroid hormone receptor alpha (TRalpha) and beta (TRbeta) cDNAs from the ovaries of the protandrous black porgy and compared the expression levels of TRalpha and TRbeta mRNA during the sex change in black porgy. We observed that the TRalpha mRNA by quantitative real-time PCR and protein levels by Western blot were highest in the mature ovaries. Additionally, TRbeta mRNA levels were only expressed highly in the mature ovaries when compared to any other gonadal stages. Then, we injected gonadotropin-releasing hormone analogue (GnRHa) to know the effects on TRs mRNA in immature black porgy. Injection with GnRHa resulted in a significant increase in TRalpha level while significantly reducing TRbeta level after 12h. We concluded that TRalpha was related in testicular development as well as ovarian development and TRbeta was only affect to ovarian development in black porgy. These results will provide a framework for better understanding of the role of TRs during sex change processes in this fish.
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Affiliation(s)
- Kwang Wook An
- Division of Marine Environment & BioScience, Korea Maritime University, Busan 606-791, Republic of Korea
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25
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Kashiwagi K, Furuno N, Kitamura S, Ohta S, Sugihara K, Utsumi K, Hanada H, Taniguchi K, Suzuki KI, Kashiwagi A. Disruption of Thyroid Hormone Function by Environmental Pollutants. ACTA ACUST UNITED AC 2009. [DOI: 10.1248/jhs.55.147] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Keiko Kashiwagi
- Institute for Amphibian Biology, Graduate School of Science, Hiroshima University
| | - Nobuaki Furuno
- Institute for Amphibian Biology, Graduate School of Science, Hiroshima University
| | | | - Shigeru Ohta
- Graduate School of Biomedical Sciences, Hiroshima University
| | - Kazumi Sugihara
- Graduate School of Biomedical Sciences, Hiroshima University
| | - Kozo Utsumi
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Hideki Hanada
- Institute for Amphibian Biology, Graduate School of Science, Hiroshima University
| | | | - Ken-ichi Suzuki
- Laboratory of Developmental Biology, Department of Biological Science, Graduate School of Science, Hiroshima University
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26
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Fort DJ, Degitz S, Tietge J, Touart LW. The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Frogs and Its Role in Frog Development and Reproduction. Crit Rev Toxicol 2008; 37:117-61. [PMID: 17364707 DOI: 10.1080/10408440601123545] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Metamorphosis of the amphibian tadpole is a thyroid hormone (TH)-dependent developmental process. For this reason, the tadpole is considered to be an ideal bioassay system to identify disruption of thyroid function by environmental contaminants. Here we provide an in-depth review of the amphibian thyroid system with particular focus on the role that TH plays in metamorphosis. The amphibian thyroid system is similar to that of mammals and other tetrapods. We review the amphibian hypothalamic-pituitary-thyroid (HPT) axis, focusing on thyroid hormone synthesis, transport, and metabolism. We also discuss the molecular mechanisms of TH action, including the role of TH receptors, the actions of TH on organogenesis, and the mechanisms that underlie the pleiotropic actions of THs. Finally, we discuss methods for evaluating thyroid disruption in frogs, including potential sites of action, relevant endpoints, candidate protocols for measuring thyroid axis disruption, and current gaps in our knowledge. The utility of amphibian metamorphosis as a model for evaluating thyroid axis disruption has recently led to the development of a bioassay using Xenopus laevis.
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Affiliation(s)
- Douglas J Fort
- Fort Environmental Laboratories, Stillwater, Oklahoma 74074, USA.
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27
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Takayama S, Hostick U, Haendel M, Eisen J, Darimont B. An F-domain introduced by alternative splicing regulates activity of the zebrafish thyroid hormone receptor alpha. Gen Comp Endocrinol 2008; 155:176-89. [PMID: 17583703 PMCID: PMC3758257 DOI: 10.1016/j.ygcen.2007.04.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 03/19/2007] [Accepted: 04/13/2007] [Indexed: 11/15/2022]
Abstract
Thyroid hormones (THs) play an important role in vertebrate development; however, the underlying mechanisms of their actions are still poorly understood. Zebrafish (Danio rerio) is an emerging vertebrate model system to study the roles of THs during development. In general, the response to THs relies on closely related proteins and mechanisms across vertebrate species, however some species-specific differences exist. In contrast to mammals, zebrafish has two TRalpha genes (thraa, thrab). Moreover, the zebrafish thraa gene expresses a TRalpha isoform (TRalphaA1) that differs from other TRs by containing additional C-terminal amino acids. C-terminal extensions, called "F domains", are common in other members of the nuclear receptor superfamily and modulate the response of these receptors to hormones. Here we demonstrate that the F-domain constrains the transcriptional activity of zebrafish TRalpha by altering the selectivity of this receptor for certain coactivator binding motifs. We found that the F-domain of zebrafish TRalphaA1 is encoded on a separate exon whose inclusion is regulated by alternative splicing, indicating a regulatory role of the F-domain in vivo. Quantitative expression analyses revealed that TRalphaA1 is primarily expressed in reproductive organs whereas TRalphaB and the TRalphaA isoform that lacks the F-domain (TRalphaA1-2) appear to be ubiquitous. The relative expression levels of these TRalpha transcripts differ in a tissue-specific manner suggesting that zebrafish uses both alternative splicing and differential expression of TRalpha genes to diversify the cellular response to THs.
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Affiliation(s)
- Sachiko Takayama
- Institutes of Molecular Biology, University of Oregon, Eugene, OR, 97403-1229, USA
| | - Ute Hostick
- Institutes of Molecular Biology, University of Oregon, Eugene, OR, 97403-1229, USA
- Neuroscience, University of Oregon, Eugene, OR, 97403-1229, USA
| | - Melissa Haendel
- Neuroscience, University of Oregon, Eugene, OR, 97403-1229, USA
| | - Judith Eisen
- Neuroscience, University of Oregon, Eugene, OR, 97403-1229, USA
| | - Beatrice Darimont
- Institutes of Molecular Biology, University of Oregon, Eugene, OR, 97403-1229, USA
- Corresponding author: Institute of Molecular Biology University of Oregon Eugene, OR, 97403-1229 Phone: (541) 346-5265 Fax: (541) 346-5891
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28
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Rates of development in male and female Wood Frogs and patterns of parasitism by lung nematodes. Parasitology 2007; 135:385-93. [DOI: 10.1017/s0031182007003836] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARYResearchers are becoming interested in testing whether investment in growth and/or development trades off against investment in parasite defence. We tested this idea by examining relations between development of Wood Frogs (Rana sylvatica) and susceptibility to lung nematodes (Rhabdias ranae). Male and female frogs reared in outdoor mesocosms were the same length and mass at metamorphosis. However, males metamorphosed sooner than females. Lung nematodes were no more likely to penetrate male versus female metamorphs following controlled exposures, but males had higher intensities of adult female worms and the largest worms per host were, on average, of larger size in male metamorphs. Males that took longer to metamorphose carried higher numbers of worms in their lungs than males that metamorphosed early. In comparison, females that developed faster harboured more worms in their lungs than females that took longer to reach metamorphosis. Our results suggest that variation in susceptibility to lung nematodes is influenced by host sex and possibly also by sex-specific relations with developmental rate. Further, male hosts might prove to be a more important source of infective stages of worms than female hosts.
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Gutleb AC, Schriks M, Mossink L, Berg JHJVD, Murk AJ. A synchronized amphibian metamorphosis assay as an improved tool to detect thyroid hormone disturbance by endocrine disruptors and apolar sediment extracts. CHEMOSPHERE 2007; 70:93-100. [PMID: 17681587 DOI: 10.1016/j.chemosphere.2007.06.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 05/21/2007] [Accepted: 06/20/2007] [Indexed: 05/16/2023]
Abstract
Amphibian metamorphosis assays are used to evaluate potential effects of endocrine disrupting compounds on the thyroid hormone axis. In this study, Xenopus laevis tadpoles are kept in a solution of 0.2% thiourea (TU) to arrest and synchronise them in their development. The advantage of this synchronized amphibian metamorphosis assays is that synchronised tadpoles are available at any time to start metamorphosis experiments, and experimental groups are much more homogenous at the start of experimental exposure compared with groups selected from an untreated pool of animals. The water volume per animal was kept constant throughout the experimental period to overcome the influence of declining numbers of animals per aquarium due to metamorphosis and mortality on the density dependent development of the remaining tadpoles. Clophen A50 (a technical PCB mixture), the single congener 3,3',4,4'-tetrachlorobiphenyl (PCB 77) and apolar sediment extracts that were previously tested positive in the T-Screen, an in vitro proliferation assay for thyroid hormone disruption, were tested in the Synchronized Amphibian Metamorphosis Assay. Endpoints studied were mortality, malformations, body weight, and percentage of metamorphosed froglets at the end of the 60-day experimental period, percentage of tadpoles in different developmental stages, and developmental stage-dependent awarded penalty points. Dietary exposure to Clophen A50 (0.2-50mg/kg food) resulted in a significant increased percentage of tadpoles that did not pass metamorphosis at concentrations higher than 2mg/kg food. Time until metamorphosis in those animals that were able to metamorphose after the 60-days experimental period was significantly decreased. Dietary exposure to PCB 77, a congener that can be readily metabolised, did not result in significant effects in any exposure group (2-500 microg/kg food). Apolar sediment extracts from two of the three sites that are contaminated with a wide variety of chemicals significantly decreased the percentage of metamorphosed animals and significantly increased the number of tadpoles that remained in early and late metamorphic stages. These effects already occurred when the extracts where diluted more than 1000 times (on an organic carbon base) compared to environmental concentrations. The rank of potency was comparable to results obtained with the T-screen. This suggests the presence of thyroid hormone disrupting compounds in the aquatic environment and possible effects of such compounds on animal development in the wild.
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Affiliation(s)
- Arno C Gutleb
- Toxicology Section, Wageningen University, Tuinlaan 5, Wageningen, The Netherlands
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Kuiper GGJM, Klootwijk W, Morvan Dubois G, Destree O, Darras VM, Van der Geyten S, Demeneix B, Visser TJ. Characterization of recombinant Xenopus laevis type I iodothyronine deiodinase: substitution of a proline residue in the catalytic center by serine (Pro132Ser) restores sensitivity to 6-propyl-2-thiouracil. Endocrinology 2006; 147:3519-29. [PMID: 16601143 DOI: 10.1210/en.2005-0711] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In frogs such as Rana and Xenopus, metamorphosis does not occur in the absence of a functional thyroid gland. Previous studies indicated that coordinated development in frogs requires tissue and stage-dependent type II and type III iodothyronine deiodinase expression patterns to obtain requisite levels of intracellular T(3) in tissues at the appropriate stages of metamorphosis. No type I iodothyronine deiodinase (D1), defined as T(4) or reverse T(3) (rT3) outer-ring deiodinase (ORD) activity with Michaelis constant (K(m)) values in the micromolar range and sensitivity to 6-propyl-2-thiouracil (6-PTU), could be detected in tadpoles so far. We obtained a X. laevis D1 cDNA clone from brain tissue. The complete sequence of this clone (1.1 kb, including poly A tail) encodes an ORF of 252 amino acid residues with high homology to other vertebrate D1 enzymes. The core catalytic center includes a UGA-encoded selenocysteine residue, and the 3' untranslated region (about 300 nt) contains a selenocysteine insertion sequence element. Transfection of cells with an expression vector containing the full-length cDNA resulted in generation of significant deiodinase activity in the homogenates. The enzyme displayed ORD activity with T(4) (K(m) 0.5 microm) and rT3 (K(m) 0.5 microm) and inner-ring deiodinase activity with T(4) (K(m) 0.4 microm). Recombinant Xenopus D1 was essentially insensitive to inhibition by 6-PTU (IC(50) > 1 mm) but was sensitive to gold thioglucose (IC(50) 0.1 mum) and iodoacetate (IC(50) 10 microm). Because the residue 2 positions downstream from the selenocysteine is Pro in Xenopus D1 but Ser in all cloned PTU-sensitive D1 enzymes, we prepared the Pro132Ser mutant of Xenopus D1. The mutant enzyme showed strongly increased ORD activity with T(4) and rT3 (K(m) about 4 microm) and was highly sensitive to 6-PTU (IC(50) 2 microm). Little native D1 activity could be detected in Xenopus liver, kidney, brain, and gut, but significant D1 mRNA expression was observed in juvenile brain and adult liver and kidney. These results indicate the existence of a 6-PTU-insensitive D1 enzyme in X. laevis tissues, but its role during tadpole metamorphosis remains to be defined.
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Affiliation(s)
- George G J M Kuiper
- Department of Internal Medicine, Room Ee 502, Erasmus Medical Center, Dr Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
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Abstract
Recent identification of new selenocysteine-containing proteins has revealed relationships between the two trace elements selenium (Se) and iodine and the hormone network. Several selenoproteins participate in the protection of thyrocytes from damage by H(2)O(2) produced for thyroid hormone biosynthesis. Iodothyronine deiodinases are selenoproteins contributing to systemic or local thyroid hormone homeostasis. The Se content in endocrine tissues (thyroid, adrenals, pituitary, testes, ovary) is higher than in many other organs. Nutritional Se depletion results in retention, whereas Se repletion is followed by a rapid accumulation of Se in endocrine tissues, reproductive organs, and the brain. Selenoproteins such as thioredoxin reductases constitute the link between the Se metabolism and the regulation of transcription by redox sensitive ligand-modulated nuclear hormone receptors. Hormones and growth factors regulate the expression of selenoproteins and, conversely, Se supply modulates hormone actions. Selenoproteins are involved in bone metabolism as well as functions of the endocrine pancreas and adrenal glands. Furthermore, spermatogenesis depends on adequate Se supply, whereas Se excess may impair ovarian function. Comparative analysis of the genomes of several life forms reveals that higher mammals contain a limited number of identical genes encoding newly detected selenocysteine-containing proteins.
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Affiliation(s)
- J Köhrle
- Institut für Experimentelle Endokrinologie, Charité, Humboldt Universität zu Berlin, Schumannstrasse 20/21, D-10098 Berlin, Germany.
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Kühn ER, De Groef B, Van der Geyten S, Darras VM. Corticotropin-releasing hormone-mediated metamorphosis in the neotenic axolotl Ambystoma mexicanum: synergistic involvement of thyroxine and corticoids on brain type II deiodinase. Gen Comp Endocrinol 2005; 143:75-81. [PMID: 15993107 DOI: 10.1016/j.ygcen.2005.02.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 02/11/2005] [Accepted: 02/28/2005] [Indexed: 11/22/2022]
Abstract
In the present study, morphological changes leading to complete metamorphosis have been induced in the neotenic axolotl Ambystoma mexicanum using a submetamorphic dose of T(4) together with an injection of corticotropin-releasing hormone (CRH). An injection of CRH alone is ineffective in this regard presumably due to a lack of thyrotropic stimulation. Using this low hormone profile for induction of metamorphosis, the deiodinating enzymes D2 and D3 known to be present in amphibians were measured in liver and brain 24h following an intraperitoneal injection. An injection of T(4) alone did not influence liver nor brain D2 and D3, but dexamethasone (DEX) or CRH alone or in combination with T(4) decreased liver D2 and D3. Brain D2 activity was slightly increased with a higher dose of DEX, though CRH did not have this effect. A profound synergistic effect occurred when T(4) and DEX or CRH were injected together, in the dose range leading to metamorphosis, increasing brain D2 activity more than fivefold. This synergistic effect was not found in the liver. It is concluded that brain T(3) availability may play an important role for the onset of metamorphosis in the neotenic axolotl.
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Affiliation(s)
- Eduard R Kühn
- Laboratory of Comparative Endocrinology, Zoological Institute, K.U.Leuven, Naamsestraat 61, Leuven B-3000, Belgium.
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Mader MM, Cameron DA. Photoreceptor differentiation during retinal development, growth, and regeneration in a metamorphic vertebrate. J Neurosci 2005; 24:11463-72. [PMID: 15601953 PMCID: PMC6730367 DOI: 10.1523/jneurosci.3343-04.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
To test the hypothesis that growth and regeneration of the adult retina involves a mechanistic recapitulation of retinal development, the patterns of photoreceptor differentiation were investigated in the developing retina, as well as growing and regenerating adult retina, of a metamorphic vertebrate, the winter flounder. Only one opsin, of type RH2 (a "green" cone opsin), was expressed in premetamorphic (developing) retina, and a corresponding middle-wavelength visual pigment was observed. In premetamorphic retinas there was no evidence for any other cone opsins or pigments, rods, rod opsin expression, or rod visual pigment. In contrast, a rod opsin (RH1) and three cone opsins (SWS2, RH2, and LWS) were expressed in postmetamorphic (adult) retina, and these opsins were consistent with the observed repertoire of visual pigments. During postmetamorphic retinal growth and regeneration, cones were always produced before rods, but the different cone types were apparently produced simultaneously, suggesting that cone differentiation mechanisms might change after metamorphosis. The results support the hypothesis that photoreceptor differentiation during growth and regeneration of the adult retina involves a recapitulation of mechanisms that control the sequence of photoreceptor production during retinal development.
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Affiliation(s)
- Michelle M Mader
- Department of Neuroscience and Physiology, and the Program in Neuroscience, State University of New York, Upstate Medical University, Syracuse, New York 13210, USA
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Szisch V, Papandroulakis N, Fanouraki E, Pavlidis M. Ontogeny of the thyroid hormones and cortisol in the gilthead sea bream, Sparus aurata. Gen Comp Endocrinol 2005; 142:186-92. [PMID: 15862562 DOI: 10.1016/j.ygcen.2004.12.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2004] [Accepted: 12/20/2004] [Indexed: 10/25/2022]
Abstract
The aim of the study was to elucidate the pattern of changes in the whole body concentrations of thyroid hormones (TH) and cortisol in eggs, pre-larvae, and larvae in the gilthead sea bream, Sparus aurata. The ontogeny of these hormones was related to specific morphological characteristics that characterize early development. TH and cortisol were detected in substantial amounts in the eggs of sea bream. T3 concentration in eggs was found to be higher than that of T4 (T3, 4.02+/-0.38 ng g-1; T4, 1.63+/-0.28 ng g-1), as it is often observed in marine teleosts. T4 decreased until hatching (T4, 1.01+/-0.58 ng g-1), while T3 reached a minimum at the time of first feeding (T3, 0.19+/-0.02 ng g-1). As development proceeded, both hormones displayed a similar pattern of changes with increasing concentrations until the completion of metamorphosis (T3, 15.84+/-2.92 ng g-1; T4, 9.78+/-2.39 ng g-1), indicating that the hypothalamo-adenohypophysial-thyroid axis begins to function soon after first feeding. The pattern of changes of cortisol (F) concentration was almost parallel to that of T4, starting from 0.83 ng g-1 in eggs. Minimum F concentration was observed at hatching (0.39+/-0.03 ng g-1) and maximum at melanophores and scale formation (14.82+/-2.71 and 14.82+/-3.12 ng g-1, respectively). Results provide data for the first time on the ontogeny of thyroid hormones and cortisol during the early development in sea bream and are in agreement with results in other fish species for an important action of TH during early development.
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Affiliation(s)
- V Szisch
- Department of Biology, University of Crete, P.O. Box 2208, GR-71409 Heraklion, Crete, Greece
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35
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Yehuda-Shnaidman E, Kalderon B, Bar-Tana J. Modulation of mitochondrial transition pore components by thyroid hormone. Endocrinology 2005; 146:2462-72. [PMID: 15691897 DOI: 10.1210/en.2004-1161] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thyroid hormone (TH) modulates metabolic efficiency by controlling the coupling of mitochondrial oxidative phosphorylation. However, its uncoupling mode of action is still enigmatic. Treatment of Jurkat or GH3 cells with T3 is reported here to result in limited, Cyclosporin A-sensitive mitochondrial depolarization, conforming to low conductance gating of the mitochondrial transition pore (MTP). MTP protein components induced by T3 treatment were verified in T3-treated and hypothyroid rat liver as well as in Jurkat cells. T3 treatment resulted in increase in mitochondrial Bax and Bak together with decreased mitochondrial Bcl2. T3-induced mitochondrial depolarization was aborted by overexpression of Bcl2. In contrast to Bax-Bcl2 family proteins, some other MTP components were either not induced by T3 (e.g. voltage-dependent anion channel) or were induced, but were not involved in Cyclosporin A-sensitive MTP gating (e.g. Cyclophilin D and adenine nucleotide translocase-2) Hence, TH-induced mitochondrial uncoupling may be ascribed to low conductance MTP gating mediated by TH-induced increase in mitochondrial proapoptotic combined with a decrease in mitochondrial antiapoptotic proteins of the Bax-Bcl2 family.
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Affiliation(s)
- Einav Yehuda-Shnaidman
- Department of Human Nutrition and Metabolism, Hebrew University Medical School, Jerusalem 91120, Israel
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Gutleb AC, Meerts IATM, Bergsma JH, Schriks M, Murk AJ. T-Screen as a tool to identify thyroid hormone receptor active compounds. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2005; 19:231-8. [PMID: 21783481 DOI: 10.1016/j.etap.2004.06.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2004] [Accepted: 06/24/2004] [Indexed: 05/21/2023]
Abstract
The T-Screen represents an in vitro bioassay based on thyroid hormone dependent cell proliferation of a rat pituitary tumour cell line (GH3) in serum-free medium. It can be used to study interference of compounds with thyroid hormone at the cellular level, thus bridging the gap between limitations of assays using either isolated molecules (enzymes, transport proteins) or complex in vivo experiments with all the complex feedback mechanisms present. Compounds are tested both in the absence and presence of thyroid hormone (EC(50) concentration of T(3)) to test for both agonistic and antagonistic potency. Thyroid hormones (3,3'-5-triiodothyronine: T(3) and 3,3',5,5'-tetraiodothyroxine: T(4)) and compounds resembling the structure of thyroid hormones (3,3'-5-triiodothyroacetic acid: Triac; 3,3',5,5'-tetraiodothyroacetic acid: Tetrac) induced cell growth, with the rank order Triac > T(3) > Tetrac > T(4) (relative potency = 1.35 > 1 > 0.29 > 0.07), which is identical to published affinities of these compounds for nuclear thyroid hormone receptors. Exposure to 5,5'-diphenylhydantoin (DPH) in the presence of 0.25nM T(3) resulted in up to 60% decreased cell growth at 200μM DPH. No effect of DPH on basal metabolic activity of GH3 cells was observed at this concentration. Fentinchloride (IC(50) = 21nM) decreased cell growth induced by 0.25nM T(3), whereas parallel exposure to these concentrations in the absence of T(3) did not alter basal metabolic activities of GH3 cells. Apolar sediment extracts from the Dommel (34%) and Terneuzen (14%) decreased cell growth in the presence of 0.25nM T(3), whereas the extract from Hoogeveen increased cell growth (26%) and the extract from North Sea Channel had no effect. The T-Screen proved to be a fast and functional assay for assessing thyroid hormone receptor active potencies of pure chemicals or environmental mixtures.
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Affiliation(s)
- Arno C Gutleb
- Toxicology Section, Wageningen University, Tuinlaan 5, NL-6703 HE Wageningen, The Netherlands
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37
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Aroua S, Schmitz M, Baloche S, Vidal B, Rousseau K, Dufour S. Endocrine evidence that silvering, a secondary metamorphosis in the eel, is a pubertal rather than a metamorphic event. Neuroendocrinology 2005; 82:221-32. [PMID: 16679776 DOI: 10.1159/000092642] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Accepted: 02/20/2006] [Indexed: 11/19/2022]
Abstract
Silvering (transition from yellow to silver eel) has been traditionally considered as a metamorphosis in view of the numerous morphological, physiological and behavioral changes preparing the eel for the oceanic migration. However, some changes, such as increases in gonad weight and steroidogenesis, suggest that silvering could also be considered as a pubertal event. In order to assess which endocrine axis may be involved in the induction of silvering, we compared the profiles of pituitary and peripheral hormones during the transition from yellow to silver female eels. A strong activation of the gonadotropic axis was shown during silvering. Follicle-stimulating hormone (FSH) mRNA levels increased during the early stages of silvering, followed by a later increase in luteinizing hormone (protein and mRNA) levels. In addition, plasma levels of sexual steroids (estradiol, E2; testosterone, T, and 11-ketotestosterone) and of vitellogenin significantly increased. In contrast, thyrotropin mRNA levels did not change and no or weak variations in plasma thyroid hormones were observed, indicating no or moderate change of the thyrotropic axis during silvering. Similarly, the somatotropic axis was not activated, as shown by pituitary growth hormone expression (protein and mRNA) and plasma levels. In addition, we studied the effects of chronic treatments of female yellow eels with thyroid hormone (thyroxine, T4) and sex steroids (T and E2) on biometrical parameters characteristics of silvering. T induced an increase in eye size and a reduction of digestive tract, whereas T4 and E2 had no effect. These hormonal profiles and experimental data lead to the conclusion that eel silvering should be considered as an onset of puberty rather than a 'genuine' metamorphosis.
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Affiliation(s)
- Salima Aroua
- MNHN, Département des Milieux et Peuplements Aquatiques, USM 0401, UMR 5178 CNRS, Paris, France
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Amiel-Tison C, Cabrol D, Denver R, Jarreau PH, Papiernik E, Piazza PV. Fetal adaptation to stress: Part II. Evolutionary aspects; stress-induced hippocampal damage; long-term effects on behavior; consequences on adult health. Early Hum Dev 2004; 78:81-94. [PMID: 15223113 DOI: 10.1016/j.earlhumdev.2004.03.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/04/2004] [Indexed: 10/26/2022]
Abstract
Humans share adaptative capacities to stress with other species, as demonstrated on amphibians: the physiological response to experimental water volume and food deprivation results in the activation of the endocrine axes that drive metamorphosis, in particular the neuroendocrine stress system. Unfavorable effects may, however, occur, probably due to inappropriate timing and/or duration of stress: recent experiments are converging to show a profound impairment of hippocampal functioning in the offspring of mothers exposed to prenatal stress. Moreover, fetal changes are likely one of the risk factors for a number of diseases in adulthood.
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Affiliation(s)
- Claudine Amiel-Tison
- Department of Pediatrics, Port-Royal, University of Paris V, 75014 Paris, France.
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Guedes JRP, Ferreira CM, Guimarães HMB, Saldiva PHN, Capelozzi VL. Homeopathically prepared dilution of Rana catesbeiana thyroid glands modifies its rate of metamorphosis. HOMEOPATHY 2004; 93:132-7. [PMID: 15287432 DOI: 10.1016/j.homp.2004.04.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
One strand of research on the scientific basis of homeopathy is based on inversion effects of dilutions and the biophysical properties of information transfer. A model developed by Endler, was the basis for the study of the influence of high-diluted solution (1:1026 part by weight) of thyroid glands on the rate of metamorphosis of the frog Rana catesbeiana from the no legged to four-legged stage. The glands were obtained from tadpoles and prepared according by (dilution and succussion). Similar pure hydroalcoholic solution (unsuccussed) was used as control. In order to identify significant differences in the frequencies of four-legged tadpoles, in homeopathic and control group, we used a chi-square goodness-of-fit test (P<0.01) and the cumulative risk for metamorphosis by Cox's Proportional Hazards model (P<0.05). The number of animals that reached the four-legged stage is generally smaller in the treated group, than in the hydroalcoholic control group. It was postulated that thyroid hormones transmitted information' specific to the molecules used to prepare the solution, even though the molarity was beyond Avogadro's number.
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Affiliation(s)
- J R P Guedes
- Laboratory of Molecular Pathology, University of São Paulo School of Medicine, SP, Brazil
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40
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Kühn ER, De Groef B, Grommen SVH, Van der Geyten S, Darras VM. Low submetamorphic doses of dexamethasone and thyroxine induce complete metamorphosis in the axolotl (Ambystoma mexicanum) when injected together. Gen Comp Endocrinol 2004; 137:141-7. [PMID: 15158126 DOI: 10.1016/j.ygcen.2004.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Revised: 03/05/2004] [Accepted: 03/10/2004] [Indexed: 11/30/2022]
Abstract
Entanglement of functions between the adrenal (or interrenal) and thyroid axis has been well described for all vertebrates and can be tracked down up to the level of gene expression. Both thyroid hormones and corticosteroids may induce morphological changes leading to metamorphosis climax in the neotenic Mexican axolotl (Ambystoma mexicanum). In a first series of experiments, metamorphosis was induced with an injection of 25 microg T(4) on three alternate days as judged by a decrease in body weight and tail height together with complete gill resorption. This injection also resulted in elevated plasma concentrations of T(3) and corticosterone. Previous results have indicated that the same dose of dexamethasone (DEX) is ineffective in this regard (Gen. Comp. Endocrinol. 127 (2002) 157). In a second series of experiments low doses of T(4) (0.5 microg) or DEX (5 microg) were ineffective to induce morphological changes. However, when these submetamorphic doses were injected together, morphological changes were observed within one week leading to complete metamorphosis. It is concluded that thyroid hormones combined with corticosteroids are essential for metamorphosis in the axolotl and that only high doses of either thyroid hormone or corticosteroid can induce morphological changes when injected separately.
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Affiliation(s)
- Eduard R Kühn
- Laboratory of Comparative Endocrinology, Zoological Institute, K.U. Leuven, Naamsestraat 61, Leuven B-3000, Belgium.
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Amicarelli F, Falone S, Cattani F, Alamanou MT, Bonfigli A, Zarivi O, Miranda M, Ragnelli AM, Di Ilio C. Amphibian transition to the oxidant terrestrial environment affects the expression of glutathione S-transferases isoenzymatic pattern. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1691:181-92. [PMID: 15110998 DOI: 10.1016/j.bbamcr.2004.02.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2003] [Revised: 02/10/2004] [Accepted: 02/16/2004] [Indexed: 11/18/2022]
Abstract
It has been postulated that glutathione S-transferases (GST; EC 2.5.1.18) may play a role in protecting against oxidative stress. In previous studies, we have purified and characterised from Bufo bufo embryos a GST isoenzyme (BbGSTP1-1), which falls at very low level in the adult liver, where a novel isoform (BbGSTP2-2), starts to be highly expressed. During transition to adult life, B. bufo leaves the aquatic environment to live predominantly in the terrestrial environment, characterised by higher oxygen concentration. It has been found that BbGSTP2-2 is more efficient in scavenging from organic hydroperoxides. Therefore, the appearance of BbGSTP2-2 may respond to the necessity of providing the adult toad with a more suitable protection against oxygen toxic by-products. In this work, we performed experiments aimed at verifying if oxidative stress (hyperoxic and H(2)O(2) treatments) could act as a modulator of BbGSTP2-2 expression. Results show that: (a) BbGSTP2 mRNA starts to be expressed in the late embryonic period, while protein appears during metamorphosis; (b) oxidative stress induces anticipation of BbGSTP2 gene expression at both transcriptional and translational levels. These findings seem to indicate that the appearance of BbGSTP2-2 is aimed at endowing the adult toad with more efficient antioxidant defence in the terrestrial atmosphere.
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Affiliation(s)
- Fernanda Amicarelli
- Department of Basic and Applied Biology, Faculty of Sciences, University of L'Aquila, Via Vetoio Loc, Coppito 67100 (AQ), Italy.
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Ward RE, Evans J, Thummel CS. Genetic Modifier Screens in Drosophila Demonstrate a Role for Rho1 Signaling in Ecdysone-Triggered Imaginal Disc Morphogenesis. Genetics 2003; 165:1397-415. [PMID: 14668390 PMCID: PMC1462826 DOI: 10.1093/genetics/165.3.1397] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Abstract
Drosophila adult leg development provides an ideal model system for characterizing the molecular mechanisms of hormone-triggered morphogenesis. A pulse of the steroid hormone ecdysone at the onset of metamorphosis triggers the rapid transformation of a flat leg imaginal disc into an immature adult leg, largely through coordinated changes in cell shape. In an effort to identify links between the ecdysone signal and the cytoskeletal changes required for leg morphogenesis, we performed two large-scale genetic screens for dominant enhancers of the malformed leg phenotype associated with a mutation in the ecdysoneinducible broad early gene (br1). From a screen of >750 independent deficiency and candidate mutation stocks, we identified 17 loci on the autosomes that interact strongly with br1. In a complementary screen of ∼112,000 F1 progeny of EMS-treated br1 animals, we recovered 26 mutations that enhance the br1 leg phenotype [E(br) mutations]. Rho1, stubbloid, blistered (DSRF), and cytoplasmic Tropomyosin were identified from these screens as br1-interacting genes. Our findings suggest that ecdysone exerts its effects on leg morphogenesis through a Rho1 signaling cascade, a proposal that is supported by genetic interaction studies between the E(br) mutations and mutations in the Rho1 signaling pathway. In addition, several E(br) mutations produce unexpected defects in midembryonic morphogenetic movements. Coupled with recent evidence implicating ecdysone signaling in these embryonic morphogenetic events, our results suggest that a common ecdysone-dependent, Rho1-mediated regulatory pathway controls morphogenesis during the two major transitions in the life cycle, embryogenesis and metamorphosis.
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Affiliation(s)
- Robert E Ward
- Howard Hughes Medical Institute, Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah 84112-5331, USA
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43
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Abstract
Thyroid hormone appears to play a critical, yet not fully understood, role in the development of the neuroretina. This review focuses on recent experiments in the rodent, chicken, and amphibian, with an emphasis on how the hormone and its receptor isoforms influence retinal cell proliferation and cell fate decisions. The initial results are fueling the next generation of experiments in the retina, which promise to provide insights into the mechanisms of thyroid hormone action in a wide variety of developing neural tissue.
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Affiliation(s)
- Sanjiv Harpavat
- Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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Katz U, Rozman A, Gabbay S. Skin epithelial transport and structural relationships in naturally metamorphosing Pelobates syriacus. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, COMPARATIVE EXPERIMENTAL BIOLOGY 2003; 298:1-9. [PMID: 12840833 DOI: 10.1002/jez.a.10258] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The onset of active Na(+) transport and activated Cl(-) conductance (G(Cl)) across the skin epithelium of Pelobates syriacus was investigated during natural ontogenetic development. Structural features, including band three and Peanut lectin bindings were tested in parallel and structure-function relationships were attempted. The 22 specimens studied were divided into two tadpole, three juvenile, and two adult stages, corresponding to the Taylor-Kollros standard table, in accordance with external morphology of their developmental stage. Onset of transepithelial electrical potential and drop in conductance occurred abruptly, coinciding with metamorphosis climax of tadpoles into juveniles at about stage XXI of development. Amiloride-sensitive Na(+) transport occurred a little later at stage XXIII, followed by the appearance of activated Cl(-) conductance, G(Cl). Parallel structural examination showed that skin MR cells occurred upon metamorphosis, as the tadpole integument transformed into the adult epithelium and could be associated with the occurrence of activated G(Cl). It was not related temporally with the appearance of band three protein in MR cells. Our findings support the association of G(Cl) with MR cells, whereas band three may only be a corollary of G(Cl) and not necessarily essential for its manifestation.
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Affiliation(s)
- Uri Katz
- Department of Biology, Technion, Israel Institute of Technology Haifa, Israel.
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45
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Abstract
The genetic and developmental bases for trait expression and variation in adults are largely unknown. One system in which genes and cell behaviors underlying adult traits can be elucidated is the larval-to-adult transformation of zebrafish, Danio rerio. Metamorphosis in this and many other teleost fishes resembles amphibian metamorphosis, as a variety of larval traits (e.g., fins, skin, digestive tract, sensory systems) are remodeled in a coordinated manner to generate the adult form. Among these traits is the pigment pattern, which comprises several neural crest-derived pigment cell classes, including black melanophores, yellow xanthophores, and iridescent iridophores. D. rerio embryos and early larvae exhibit a relatively simple pattern of melanophore stripes, but this pattern is transformed during metamorphosis into the more complex pattern of the adult, consisting of alternating dark (melanophore, iridophore) and light (xanthophore, iridophore) horizontal stripes. While it is clear that some pigment cells differentiate de novo during pigment pattern metamorphosis, the extent to which larval and adult pigment patterns are developmentally independent has not been known. In this study, we show that a subset of embryonic/early larval melanophores persists into adult stages in wild-type fish; thus, larval and adult pigment patterns are not completely independent in this species. We also analyze puma mutant zebrafish, derived from a forward genetic screen to isolate mutations affecting postembryonic development. In puma mutants, a wild-type embryonic/early larval pigment pattern forms, but supernumerary early larval melanophores persist in ectopic locations through juvenile and adult stages. We then show that, although puma mutants undergo a somatic metamorphosis at the same time as wild-type fish, metamorphic melanophores that normally appear during these stages are absent. The puma mutation thus decouples metamorphosis of the pigment pattern from the metamorphosis of many other traits. Nevertheless, puma mutants ultimately recover large numbers of melanophores and exhibit extensive pattern regulation during juvenile development, when the wild-type pigment pattern already would be completed. Finally, we demonstrate that the puma mutant is both temperature-sensitive and growth-sensitive: extremely severe pigment pattern defects result at a high temperature, a high growth rate, or both; whereas a wild-type pigment pattern can be rescued at a low temperature and a low growth rate. Taken together, these results provide new insights into zebrafish pigment pattern metamorphosis and the capacity for pattern regulation when normal patterning mechanisms go awry.
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Affiliation(s)
- David M Parichy
- Section of Integrative Biology, Section of Molecular, Cell and Developmental Biology, Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station, C0930, Austin, TX 78712, USA.
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Carpizo-Ituarte E, Hadfield MG. Transcription and translation inhibitors permit metamorphosis up to radiole formation in the serpulid polychaete Hydroides elegans haswell. THE BIOLOGICAL BULLETIN 2003; 204:114-125. [PMID: 12700142 DOI: 10.2307/1543547] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Settlement and metamorphosis in most well-studied marine invertebrates are rapid processes, triggered by external cues. How this initial environmentally mediated response is transduced into morphogenetic events that culminate in the formation of a functional juvenile is still not well understood for any marine invertebrate. The response of larvae of the serpulid polychaete Hydroides elegans to inhibitors of mRNA and protein synthesis was examined to determine if metamorphosis requires these molecular processes. Competent larvae of H. elegans were induced to metamorphose by exposing them to a bacterial film or a 3-h pulse of 10 mM CsCl in the presence of the gene-transcription inhibitor DRB (5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole) or the translation inhibitor emetine. When induced to metamorphose in the presence of either inhibitor, larvae of H. elegans progressed through metamorphosis to the point at which branchial radioles start to develop. DRB and emetine inhibited the incorporation of radiolabeled uridine into RNA and radiolabeled methionine into peptides, respectively, indicating that they were effective in blocking the appropriate syntheses. Taken together, these results indicate that the induction of metamorphosis in H. elegans does not require de novo transcription or translation, and that the form of the juvenile worm is achieved in two phases. During the first phase, larvae respond to the inducer by attaching to the substratum, secreting a primary tube, resorbing the prototroch cilia, undergoing caudal elongation, and differentiating the collar; once the collar is formed, they begin secreting the secondary, calcified tube. During the second phase, the small worm develops branchial radioles and begins to grow, requiring new mRNA and protein syntheses.
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Lim W, Nguyen NH, Yang HY, Scanlan TS, Furlow JD. A thyroid hormone antagonist that inhibits thyroid hormone action in vivo. J Biol Chem 2002; 277:35664-70. [PMID: 12095994 DOI: 10.1074/jbc.m205608200] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have characterized the newly developed thyroid hormone antagonist NH-3 in both cell culture and in vivo model systems. NH-3 binds Xenopus laevis thyroid hormone receptors directly in vitro and induces a conformation distinct from agonist-bound receptors. Transcriptional activation of a thyroid hormone response element-containing reporter gene is strongly inhibited by NH-3 in a dose-dependent manner. In addition, NH-3 prevents X. laevis thyroid hormone receptors from binding to the p160 family of co-activators GRIP-1 and SRC-1 in a two-hybrid assay. To assess the potency of the compound in vivo, we used induced and spontaneous X. laevis tadpole metamorphosis, a thyroid hormone-dependent developmental process. NH-3 inhibits thyroid hormone-induced morphological changes in a dose-dependent manner and inhibits the up-regulation of endogenous thyroid hormone-responsive genes. Spontaneous metamorphosis is efficiently and reversibly arrested by NH-3 with at least the same effectiveness as the thyroid hormone synthesis inhibitor methimazole. Therefore, NH-3 is the first thyroid hormone antagonist to demonstrate potent inhibition of thyroid hormone action in both cell culture- and whole animal-based assays.
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Affiliation(s)
- Wayland Lim
- Section of Neurobiology, Physiology, and Behavior, University of California, Davis, California 95616-8519, USA
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Dumont JE, Dremier S, Pirson I, Maenhaut C. Cross signaling, cell specificity, and physiology. Am J Physiol Cell Physiol 2002; 283:C2-28. [PMID: 12055068 DOI: 10.1152/ajpcell.00581.2001] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The literature on intracellular signal transduction presents a confusing picture: every regulatory factor appears to be regulated by all signal transduction cascades and to regulate all cell processes. This contrasts with the known exquisite specificity of action of extracellular signals in different cell types in vivo. The confusion of the in vitro literature is shown to arise from several causes: the inevitable artifacts inherent in reductionism, the arguments used to establish causal effect relationships, the use of less than adequate models (cell lines, transfections, acellular systems, etc.), and the implicit assumption that networks of regulations are universal whereas they are in fact cell and stage specific. Cell specificity results from the existence in any cell type of a unique set of proteins and their isoforms at each level of signal transduction cascades, from the space structure of their components, from their combinatorial logic at each level, from the presence of modulators of signal transduction proteins and of modulators of modulators, from the time structure of extracellular signals and of their transduction, and from quantitative differences of expression of similar sets of factors.
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Affiliation(s)
- J E Dumont
- Institute of Interdisciplinary Research, Free University of Brussels, Campus Erasme, B-1070 Brussels, Belgium.
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49
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Abstract
In zebrafish, like many other teleost species, the development and differentiation of many major organs continue unabated into the yolk-sac larval stage before culminating in a free-swimming larva capable of exogenous feeding. We investigated the role of thyroid hormone (TH) in this important embryonic to larval transitory phase. Thyroid hormone receptor (TR) alpha and beta mRNAs are expressed during the early stages of zebrafish embryonic development. Beginning from the midblastula stage, the level of TR beta mRNAs increases dramatically and is maintained until the end of the transitory phase. Excessive exogenous thyroxine (T4; 30 nM) is toxic and causes severe developmental defects. Cotreatment of embryos with amiodarone, an antagonist of TR, and goitrogen methimazole (MMI) lead to severe retardation in the maturation of the gastrointestinal system, swim bladder, and the lower jaw cartilages and the resorption of the yolk sac. The developmental arrest is lethal, and treated larvae do not survive beyond 7 day postfertilization (dpf), but can be completely rescued by the presence of 10 nM T4. We propose that the embryonic to larval transitory phase in many teleost species is characterized by its dependency on the timely synthesis of TH and the concomitant autoinductive increase in TR beta mRNA levels.
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Affiliation(s)
- Yi-Wen Liu
- Laboratory of Fish Biology, Institute of Molecular Agrobiology, 1 Research Link, National University of Singapore, S117604, Republic of Singapore
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50
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Urnov FD, Wolffe AP. An array of positioned nucleosomes potentiates thyroid hormone receptor action in vivo. J Biol Chem 2001; 276:19753-61. [PMID: 11274156 DOI: 10.1074/jbc.m100924200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The assembly of the genome into chromatin imposes a poorly understood set of rules and constraints on action by regulatory factors. We investigated the role played by chromatin infrastructure in enabling an acute response of the Xenopus TRbetaA gene to thyroid hormone receptor (TR), an extensively studied member of the nuclear hormone receptor superfamily. We found that in addition to the known TR response element (TRE) in the promoter, full range regulation required an upstream enhancer that contained multiple nonconsensus TREs and augmented ligand action at high receptor levels. An array of translationally positioned nucleosomes formed over the TRbetaA locus in vivo; unliganded TR engaged this array in linker DNA between two nucleosomes and via TREs on the surface of histone octamers. Remarkably, assembly of enhancer DNA into mature chromatin potentiated binding by TR to its target response elements and enabled a greater range of regulation by TR than was observed on immature chromatin templates. Because assembly of enhancer DNA into chromatin increased TR binding to the nonconsensus TREs, we hypothesize that chromatin disruption targeted by liganded TR to the enhancer may lead to receptor release from the template and to an attenuation of response to hormone.
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Affiliation(s)
- F D Urnov
- Sangamo Biosciences, Point Richmond Tech Center, Richmond, California 94804, USA.
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