PubMed · 12561459
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Andrew R Blaustein, Pieter T J Johnson. 2003. Explaining frog deformities.. https://doi.org/10.1038/scientificamerican0203-60
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Fifty years after Briggs and King first succeeded in obtaining normal tadpoles from transplanted embryo nuclei in vertebrates, two general principles have emerged from work in amphibia and mammals. One is the conservation of the genome during cell differentiation. A small percentage of adult or differentiated cells have totipotent nuclei, and a much higher percentage of cells committed to one pathway of cell differentiation have multipotent nuclei. The other is the remarkable reprogramming capacity of cell, and especially egg, cytoplasm. The eventual identification of reprogramming molecules and mechanisms could facilitate a route toward cell replacement therapy in humans.
The emerging infectious disease chytridiomycosis is thought to have contributed to many of the recent alarming declines in amphibian populations. Mortalities associated with these declines have often occurred during cooler seasons and at high elevations, suggesting that environmental temperature may be an important factor in disease emergence. We found that thermal environment affects the progress of the disease, and that housing frogs Litoria chloris at an environmental temperature of 37 degrees C for less than 16 h can clear them of the chytrid pathogen Batrachochytrium dendrobatidis. Our experiment demonstrated that elevated body temperatures similar to those experienced in behavioral fever and during normal thermoregulation can clear frogs of chytrid infection; therefore, variation in thermoregulatory opportunities and behaviors are likely to contribute to the differences in disease incidence observed among host species, populations, and regions. Although further refinement of the technique is needed to encompass various host species, appropriately applied thermal manipulations of amphibians and their enclosures may prove to be a safe and effective way of eliminating the fungal pathogen from captive amphibian populations and: preventing accidental spread of the pathogen when animals are translocated or released from captivity.
The expression of the long form of prolactin receptor (PRL-R) mRNAs was studied in reproductive organs from both male and female Typhlonectes compressicauda, an amphibian, by quantitative in situ hybridization. These PRL-R mRNAs were expressed in all the organs studied. In ovarian tissue, mRNAs coding for the long form of PRL-R were strongly expressed in ovaries with compact and vascularized corpora lutea, i.e., during the middle and the end of pregnancy. During the other periods of cycle, sexual rest, vitellogenesis and beginning of pregnancy, expression of these mRNAs was lower than in other periods. In the testis, mRNAs coding for the long form of PRL-R were expressed in germ cells as well as in Leydig and Sertoli cells. In müllerian glands, important variations of expression in these mRNAs have been observed with a large increase during the breeding period and a decrease during sexual rest. Variations of gene expression of the long form of PRL-R for all tissues studied are correlated to synthesis of PRL in the pituitary in both male and female Typhlonectes compressicauda.