ASSESSING THE IMPACT OF SEX-SPECIFIC MICROSATELLITE VARIANTS ON PHENOMICS OF INBRED SWISS ALBINO MICE

An inbred strain limits the segregating variance and provides more power and requires fewer experimental animals to produce good reproducibility. This study was undertaken with the aim to assess the impact of sex of offsprings and sex specific microsatellite variants on performance and fitness traits in F4 inbred Swiss albino mice. The phenomics of different performance and fitness traits were estimated on 506 F4 inbred mice population. Two ‘X' chromosome specific microsatellite loci (DXMit187 and DxMit172) were used for PCR-Microsatellite genotyping of 102 F4 inbred population. PIC estimates showed that both the loci were informative for the population. In the current population, with the increasing level of “F” a declining trend was observed for Body weight at birth (BWB), Body weight at weaning (BWW), Litter size at weaning (LSW) and Litter weight at weaning (LWW). In F4 inbred population, BWW and ABW for males (17.32±0.32g and 30.81±0.31g) were significantly (p<0.05) higher than females (16.39±0.30g and 27.83±0.28g). The significant (p<0.05) impact of sex of offspring on performance traits revealed that less magnitude of inbreeding depression was observed in male as compared to female. There were 3 alleles and 5 genotypes at the DXMit172 locus, and 3 alleles and 4 genotypes at the DXMit187 locus. The highest and lowest allelic frequencies were found at DXMit172 locus for 142 (0.422) and 154 (0.226) alleles, respectively, and at DXMit187 locus for 126 (0.588) and 146 (0.093) alleles, respectively. Genotype 142/142 (0.382) and 154/148 (0.059) had the highest and lowest genotypic frequency at the DXMit172 locus, respectively, and at DXMit187 locus for 126/126 (0.588) and 146/146 (0.039) genotypes, respectively. In the current study, only the DXMit172 loci had significant genotypic associations with fitness traits (p<0.05). The average FIS based on X- specific microsatellite markers was 0.790 in the F4 inbred population. These results indicate that rate of inbreeding depression is more in females than in males.