Investigating The Biocharacteristics And Mapping The Mutant Gene Of Venter-yellow Pigmentation Mouse

The venter-yellow pigmentation mouse arose spontaneously in the C57BL/6J inbred strain mouse which was found by the staff of Shanghai Laboratory Animal Center, Chinese Academy of Science. It presented a special phenotype with yellow coat on the ventral surface of head, neck and trunk (from the lower jaw to the anus) and a clear boundary between ventral side and dorsal side. This thesis about the mutant mouse includes the following two parts:Investigating the biocharacteristics and mapping mutant gene of the venter-yellow pigmentation mouse.1. The biocharacteristics of the venter-yellow pigmentation mouseThe mutation of venter-yellow pigmentation mouse was spontaneous and the mutant allele was inherited as single-gene dominant inheritance confirmed by genetic experiment. Compared with B6 through histopathologic and histochemical study, the mutant mouse was found that the number of melanocytes in epidermis and melanin in hair follicle of the abdominal skin were less than that of its background strain while there was no significant difference between the dorsal skin of the two strains; observed directly under microscopy, the ventral hair color of mutant mouse was lighter than that of wild type mouse while its structure was normal. There was no big difference in the color and structure of dorsal hair. The venter-yellow pigmentation mice had bigger kidney than B6 and statistical analysis showed this difference was highly significant (P<0.01). The serum glucose level of the mutant mouse in the male and the female were 7.64±0.820mmol/L and 7.46±0.992mmol/L while in the male and the female of B6 were 2.14±0.532mmol/L and 2.59±0.896mmol/L respectively, and the difference was also with high statistical significance (P<0.01). There were no significant differences between venter-yellow pigmentation mouse and B6 in other biological parameters such as weight, pathological sections of major organs and blood physiology. Although we have not understood the potential relationships of these changes, the high serum glucose level implies that the venter-yellow pigmentation mouse might be used as a new diabetes animal model. Also, before the human homologous disease corresponding to the venter-yellow pigmentation mouse is confirmed, these biological data of the venter-yellow pigmentation mouse will offer very useful clues to subsequent identification of mutant gene.2. Mapping the mutant gene of venter-yellow pigmentation mouseOn the basis of many materials and former achievements referenced, 39 microsatellites, which distributed equally on 19 euchromosomes of mouse with at least 4bp differences of polymorphism between B6 and DBA (D2), was prepared for genome-wide scan. Meanwhile, [B6D2F1×D2] F2 mice for mapping mutant gene were bred and 48 genomic DNA samples were preferentially scanned with microsatellites on chromosome 2 and 8. After each of the samples was amplified by primers of these microsatellites, we evaluated amplification results using linkage-analysis method, and the mutant gene was located on chromosome 2 near by D2Mit229. Consequently, the scope of mutant gene was narrowed step by step by selected microsatellite marks approaching the mutant gene. After the mutant gene was narrowed dawn to about 2.7 cM between D2Mit307 and D2Mit310, there was no suitable microsatellite to choose in Mouse Genomic Informatics ( MGI ) database , a new type maker named single-nucleotide polymorphism(SNP) was used which should show the difference of single base polymorphism between B6 and D2 by sequencing the PCR products. In this research, 11 microsatellite marks and 3 SNP marks were used to amplify 196 F2 mice and the mutant gene was narrowed down to 5.3Mb region between rs13476833 and rs27310903 on chromosome 2. Preliminary results of phenotype analysis and gene location provide a solid basis for further identification of mutant gene.