Leptin Gene Expression in Developing X. Laevis Under Nutritional Stress

Ryan Conrad, Vassar College ’11 and Prof. Erica Crespi

Leptin (ob gene product) is a type-1 cytokine hormone prominently known for its role in the inhibition of food intake in order to maintain energy homeostasis. Recently, leptin has been cloned in the amphibian model organism Xenopus laevis to reveal a highly conserved predicted tertiary protein structure with corresponding conserved function. It was also discovered that leptin can act as a growth factor in the developing limb of X. laevis, as exogenous recombinant leptin stimulates limb development. The purpose of the present study is to assess the role of leptin in the early stages of amphibian development. Leptin gene expression was measured using quantitative, real-time PCR of reverse transcribed RNA isolated from tadpoles under food restriction. Gene expression was quantified in premetamorphic tadpoles and a variety of tissues of prometamorphic tadpoles (NF 54) to analyze whether leptin acts as a signal of nutritional status during early development. Among these tissues was the budding hind limb in order to help elucidate the function of this hormone in development. Our results find that leptin gene expression was generally downregulated under nutritive stress. This finding suggests a correlation between leptin expression and food availability during early X. laevis development.