| Popis: |
The lateral line system is an unique sensory system found in fishes and amphibians. It is composed of two types of sensory organs: electroreceptors (ampullary organs) and mechanoreceptors (neuromasts). These organs are arranged in lines throughout the surface of the head and the body, and allow the animal to detect weak electric field and to sense motion in the immediate surroundings. We are interested in studying the genes involved in regulating the development of the hair cells of the neuromast organ because these hair cells are considered to be homologous to the hair cells of the vertebrate inner ear. When damaged by noise trauma, birds are capable of regenerating the hair cells of the inner ear whereas other vertebrates, such as humans, become permanently deaf. Since axolotl neuromasts are readily accessible to experimental manipulation and are capable of regeneration, they are an excellent model for studying the genes involved in the development and regeneration of hair cells. Two gene families that play extensive roles in pattern formation during embryonic development are the msx and dlx homeobox-containing genes. Members from both families are expressed in the developing hair cells of the zebrafish inner ear, and therefore are excellent candidates for regulating the development of the neuromast organs in axolotls. As a first step towards examining the expression of members of these two families in the axolotl, we have cloned the cDNA sequences of msx-1, msx-2, dlx-3, dlx-5, and dlx-7. In addition, we have cloned the homeobox portions of the axolotl dlx-1 and dlx-6 genes. We also provide evidence of two different transcripts for the axolotl dlx-3 gene suggesting the existance of two copies of this gene in the axolotl genome. |
