Two New Scant Hair Mice Induced By ENU And Mapping Of The Mutant Gene On Chromosome

Alopecia is a common illness in human and has certain inceidence. The causes of this disease occurring include inherent and environmental factors, such as pressure, food, disorder of nerve, X-ray, drug and so on. However, the causes of alopecia haven't been known much. It is high homogenous on genome between human and mouse, so the mouse of coat mutant is a scarce animal model to study mechanism of hair growing and alopecia, for instance hairless mouse and scant hah mouse. This mutant mouse can be obtained by spontaneity or artificial method. In this paper, two new scant hair mice were obtained by ENU inducing and mutant genes were mapped on chromosome. This study consists of three parts:l.Two new coat mutant mice induced by ENU18 DBA/2 male mice of 8-10 weeks old were injected intraperitoneally with a dose of ENU l00mg/Kg once a week and total three times. Mated with the same strain female mice, their progeny were screened for mutations. The progeny who carried mutant phenotypes mated with the same strain mice. If the mutant phenotypes were monitored in the progeny, this mutation may be dominant mutation. Some male GI mice without abnormal phenotype selected randomly mating with female C57BL/6J mice produced FI mice, and F2 mice were gained by F1 intercrossing. If mutant phenotypes appeared in F2, the existence of recessive mutation might be determined. The results indicated that in 532 GI mice, there were 14 mice carrying mutant phenotypes, but none of these abnormal phenotypes was inheritable. On the other hand, we gained two mutation strains showing recessive heredity during the recessive heredity test of 30 GI mice. The two mutation strains all showed scant hair and developed slowly, named snthr-1Baoandsnthr-2Bao.2. Primary study on histological structure of two new scant hair miceTaking heart, liver, spleen, lung, kidney, brain, lymphoma, thymus and skin of normal DBA/2 mouse and scant hair mouse, respectively. To observe the histological structure of scant hair mice by using ten percent formaldehyde fixed, paraffin section, and staining with hematoxylin and eosin. The results indicated that all organs of scant hair mouse hade no difference with normal mouse but skin was thinner than normal mouse's, the number of hair follicle was few and hair follicle hyperkeratosis.3. Mapping the Mutant Genes of two New Scant Hair MiceTwo new scant hair mice, named snthr"1Bao and snthr"2Bao, had been obtained by ENU-induced mutagenesis, and the method of linkage analysis was employed to map these mutant genes. We selected 39 microsatellites, distributed on the mouse autosomal chromosome and were polymorphic between C57BL/6J and DBA/2, to scan the genome after discrimination of the scant hair mice in the F2 of snthr"IBao, the offspring of B6D2F1. After we had screened 9 microsatellites, we found that the log odds score (LODS) between snthr"1Bao and D9MU243 was 7.73, which indicated that the mutant gene was located on chromosome 9. And then we selected microsatellites D9Mit355 and D9Mitl8 to test all samples again, and the amount of the scant hair ?2 was up to 145. The LODS of snthr"1Baoand D9Mitl8 was 87.30 and no one case of recombination was found. Data showed that mutation gene of snthr"1Bao closely linked D9Mit 18 about 71cM from the centromere. By the same way, snthr"28*0 was mapped nearby snthr"IBao. After searching the Mouse Genomic Database, snthr"1 Bao is found to be a new gene that has not been cloned.In summary, these tentative experiments provide referential data to exploit the mutant mouse strains of our country and provide basical groundwork to clong the scant hair gene.