Breeding Three Kinds Of Scant Hair Mice Through The Strategy Of Artificial Reproduction And Introgression

Introgression is an effective method to breed mouse model. In this study, three novel congenic lines were obtained through introducing the target genomic fragments into the new genetic background by repeated mating strategy and selection based on microsatellite markers and alopecia areata phenotype.1Breeding two kinds of congenic mice with Plcdl modifiers marked by microsatellitesIn preliminary work, it was found that there were four loci on C57BL/6J mice genome which had significant moderating role in the extent of sparse hair of snthr-IBao against the DBA/2J background. In this study, three microsatellite markers were selected within one of the four genetic regions with the moderating effect. They were D2Mit156, D2Mit249, D2Mit62for the range of32-68cM on chromosome2; D5Mit356, D5Mit314, D5Mit409for the range of24-84cM on chromosome5; D7Mit230, D7Mit318, D7Mit203for the range of18-58cM on chromosome7; and D15Mit71, D15Mit29, D15Mit171for the range of42.7-52.7cM on chromosome15respectively. C57BL/6J mice were mated with snthr-IBao mice. Offspring with C57BL/6J corresponding genomic fragments which were selected by microsatellite markers, intercrossed, whose offspring were continued mating with snthr-1Bao mice. After six consecutive times of backcrossing, last time intercrossing and selection, we gained two kinds of snthr-1Bao scant hair mice carrying the genomic fragments of Chromosome2and Chromosome15of C57BL/6J mice respectively, whose regulating effects were confirmed that the modification site of chromosome2could exacerbate Alopecia Areata symptoms, resulting in hair density decreased, but the modification site of chromosome15could reduce Alopecia Areata symptoms, resulting in hair density increased. The congenic mice with the Chromosome5and Chromosome7modifiers were failed to be bred. So in this study, we provide two novel Alopecia Areata models for the mechanism research of related genes and cosmetics evaluation. 2Breeding a congenic mouse with the Alopecia Areata against C57BL/6J genetic backgroundAlopecia Areata (AAtj) mouse, showing single gene recessive heredity, was found in the Kunming mice. Its coat density was normal in childhood, along with increasing age, the back hair was focal sparse and progressive slowly, and finally almost hairless, which was similar to the clinical symptoms of human Alopecia Areata. As its complex genetic background, it was necessary to purify its genetic background for mapping and identifying the mutant gene of Alopecia Areata and comparing its phenotype data. In this study, Alopecia Areata mice were mated with C57BL/6J mice to produce F1mice carrying the mutant gene but without Alopecia Areata phenotype. F2mice were gained by F1intercrossing, and the mutation gene homozygous showed Alopecia Areata. The F2Alopecia Areata mice were mated with C57BL/6J mice to produce F3mice, and F4Alopecia Areata mice were gained by F3intercrossing. So until the8th generation was bred. Then, the congenic inbred mice with Alopecia Areata were maintained by intercrossing of Alopecia Areata siblings. On this basis, histopathological examination was done for the major organs in2month and skin tissues of different developmental stages of the F6Alopecia Areata mice (from birth to8weeks, once a week). It was found that the number of hair follicle gradually reduced in the AAtj mice and skin thickness increased significantly compared with the wild-type mice. The CD8-positive lymphocyte infiltration was founded around the hair follicles by immunohistochemistry study of the AAtj over four weeks old. AAtj, bred in this study, with a purified C57BL/6J background is a good material for the model assessment of human disease and a guarantee for mapping and identifying the mutant gene.