SNP Genetic Diversity Within a Fragment of the Gene Myo15a Responsible for the Hearing Process in a Population of Farmed and Free-Living Animals of the Canidae Family/SNP Genetski Deverzitet U Okviru Fragmenta Gena Myo15a, Odgovornog Za Sluh U Populaciji Životinja Familije Canidae U Uslovima Farmskog I Slobodnog Uzgoja

The gene MYO15A is involved in the production of a protein included in the group of motor proteins known as myosins. Myosin XVA is located in the inner ear, the pituitary gland and other tissues, and has a substantial influence on the hearing process. Mutations in this gene cause amino acid substitutions in the conserved motor domain of the myosin chain, leading to shortening of the stereocilia in the hair cells, so that the function of myosin XVA is impaired. A research hypothesis was put forth that mutations in the gene responsible for the hearing process in animals of the Canidae family can cause hypoacusis, as well as substantial behavioural changes in dogs (ranging from timidity to aggressive behaviour). The study determined SNP polymorphism in a fragment of the gene MYO15A, which can cause hearing disorders or hypoacusis, in wild and farmed individuals of the Canidae family.

Mosaic Complementation Demonstrates a Regulatory Role for Myosin VIIa in Actin Dynamics of Stereocilia

ABSTRACT We have developed a bacterial artificial chromosome transgenesis approach that allowed the expression of myosin VIIa from the mouse X chromosome. We demonstrated the complementation of the Myo7a null mutant phenotype producing a fine mosaic of two types of sensory hair cells within inner ear epithelia of hemizygous transgenic females due to X inactivation. Direct comparisons between neighboring auditory hair cells that were different only with respect to myosin VIIa expression revealed that mutant stereocilia are significantly longer than those of their complemented counterparts. Myosin VIIa-deficient hair cells showed an abnormally persistent tip localization of whirlin, a protein directly linked to elongation of stereocilia, in stereocilia. Furthermore, myosin VIIa localized at the tips of all abnormally short stereocilia of mice deficient for either myosin XVa or whirlin. Our results strongly suggest that myosin VIIa regulates the establishment of a setpoint for stereocilium heights, and this novel role may influence their normal staircase-like arrangement within a bundle.