During amphibian metamorphosis, TH (a circulating factor that therefore has a uniform concentration across the whole organism) induces diverse, temporally staged metamorphic changes in different tissues.
a) In a hypothetical early-responding tissue (i.e, limbs) and a hypothetical late-responding tissue (i.e, tail) draw or describe how cell type-specific expression of any combination of proteins you think would be important in determining how a specific cell would respond to TH would change over time from the beginning to the end of metamorphosis, and explain why these expression patterns would lead to differential responses in these tissues over the course of metamorphosis.
b) Compare the kinds of changes in protein expression you describe above in the context of amphibian metamorphosis with what occurs at puberty in the Guevedoces of South America, and use it to explain this phenotype.
Metamorphosis in amphibians is the transformation of the larva to a miniature adult replicate, and usually from an aquatic to a terrestrial or semi-terrestrial lifestyle. ... Metamorphosis is initiated internally and maintained by the hormone thyroxine (TH), and the process is obligatory.
During amphibian metamorphosis, TH (a circulating factor that therefore has a uniform concentration across the whole...