Thyroid Hormone and Thiourea Treatments
نویسندگان
چکیده
In order to clarify the mechanisms of neoteny in the ice goby ( Leucopsarion petersii ), we examined effects of thyroid hormone and thiourea (TU) treatments on their neotenic characteristics and the pituitary-thyroid axis. Adult ice goby were exposed to 3, 5, 3’-triiodothyronine (T3, 0.1 ppm), TU (inhibitor of thyroid hormone synthesis, 30 ppm), or the combination of the two for 2 weeks. Observations of whole body T3 levels, thyroid follicles and TSH immunoreactive cells in the pituitary suggests the presence of a functioning thyroidal system. However, all of the neotenic features did not disappear in T3-treated fish, suggesting the absence of T3 responsiveness in peripheral tissues. These results indicate the similarity between neoteny of the ice goby and obligatory-type neoteny of urodeles.
منابع مشابه
Heterochronic developmental shift caused by thyroid hormone in larval sand dollars and its implications for phenotypic plasticity and the evolution of nonfeeding development.
Recent work on a diverse array of echinoderm species has demonstrated, as is true in amphibians, that thyroid hormone (TH) accelerates development to metamorphosis. Interestingly, the feeding larvae of several species of sea urchins seem to obtain TH through their diet of planktonic algae (exogenous source), whereas nonfeeding larvae of the sand dollar Peronella japonica produce TH themselves (...
متن کاملThyroid hormone effects on chick scale morphogenesis and keratinization.
The effects of thiourea injection on scale development were studied in New Hampshire Red x White Leghorn Cross chick embryos. Normal morphogenesis and keratinization of scales were significantly delayed in thioureatreated specimens. Subsequent thyroxine injection resulted in normal or even precocious scale development. The thyroid hormone responsiveness of scale development is discussed in rela...
متن کاملNotes on Some Remedies
investigate its toxicity to the rat. They noted that animals dying after sulphaguanidine showed goitres which on microscopical section were found to be due to hyperplasia and were practically free from colloid. The same effect was produced more or less by other sulpha drugs such as sulphadiazine and sulphapyridine, and Richter and Clisby (1942) showed that other sulphur compounds, notably thiou...
متن کاملEthylene thiourea: thyroid function in two groups of exposed workers.
Ethylene thiourea is manufactured at one factory in the United Kingdom and is mixed into masterbatch rubber at another. Clinical examinations and thyroid function tests were carried out over a period of three years on eight process workers and five mixers and on matched controls. The results show that the exposed mixers, but not exposed process workers, have significantly lower levels of total ...
متن کاملMode of carcinogenic action of pesticides inducing thyroid follicular cell tumors in rodents.
Of 240 pesticides screened for carcinogenicity by the U.S. Environmental Protection Agency Office of Pesticide Programs, at least 24 (10%) produce thyroid follicular cell tumors in rodents. Thirteen of the thyroid carcinogens also induce liver tumors, mainly in mice, and 9 chemicals produce tumors at other sites. Some mutagenic data are available on all 24 pesticides producing thyroid tumors. M...
متن کامل