Tensor tympani- The tensor tympani is the larger of the two muscles of the auditory canal, the other being stapedius. The muscle functions to dampen down sounds such as chewing. It arises from the cartilaginous portion of the eustachian tube as well as the adjacent section of the greater wing of the sphenoid bone.
A nonsense mutation in the leptin gene that results in a stop codon and lack of leptin production was first observed in mice in 1950. In the mouse gene, arginine-105 is encoded by CGA and only requires one nucleotide change to create the stop codon TGA.
Leptin is opposed by the actions of the hormone ghrelin, the hunger hormone. Both hormones act on receptors in the arcuate nucleus of the hypothalamus to regulate appetite to achieve energy homeostasis.hen leptin binds with the leptin receptor, it activates a number of pathways. Leptin resistance may be caused by defects in one or more part of this process, particularly the JAK / STAT pathway. Mice with a mutation in the leptin receptor gene that prevents the activation of STAT3 are obese and exhibit hyperphagia.