Previous studies have shown how the thyroid hormone receptor alpha plays a key function in hind limb development in frogs. Using advanced gene mutation technology, scientists have been able to mutate the gene in the tadpoles. This could be revealing about human development.
Essentially what the researchers have done is to disrupt the developmental timing of the hind limbs. This has shown the key role of the thyroid hormone receptor. The argument is that this hormone receptor is important in the early development of all vertebrates, including people.
The research also found that tadpoles do not metamorphose in the absence of hormones. Instead they simply become larger tadpoles. This was shown by running multiple tests and interefring with the hormone at different stages.
What does this mean for humans? Frog metamorphosis has been compared to birth in humans. This is because during frog metamorphosis there is a peak in blood levels of thyroid hormones. Therefore scientists are keen to study this hormone, with a particular interest in birth defects. In people, the absence of the hormone creates the condiiton cretinism. Here the person has short stature and mental retardation. Approximately 1 in 4000 newborn infants has a severe deficiency of thyroid function. If left untreated for several months after birth, severe congenital hypothyroidism triggers the growth failure and intellectual disability.
The research has been published in the journal Endocrinology and the paper is titled “Unliganded Thyroid Hormone Receptor α Regulates Developmental Timing via Gene Repression in Xenopus tropicalis.”
