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.
The retinal degeneration 1 mutation (Pde6brd1, phophodiesterase 6B, cGMP, rod receptor, beta polypeptide) is present in a number of common inbred strains of mice, including some of those used to make transgenic mice (B6SJLF1/J, B6CBAF1/J and FVB/NJ).Pde6brd1 is recessive and causes blindness by weaning.he hybrid mice (B6SJLF1/J and B6CBAF1/J) segregate Pde6brd1 contributed by SJL or CBA. Unless a transgene integrates close to Pde6b, both blind and sighted transgenic progeny may be produced when B6SJLF1/J and B6CBAF1/J are used.