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[Expression of the mutant gene mi in mice: white spotting pattern]
Abstract:
Mice of mi/+ and +/+ genotypes of the mutant stock microphthalmia (mi) were mated inter se and with those of CC57BR/Mv and CBA/J inbred lines. In all types of crosses, the offsprings of mi/+ genotype had unpigmented fingers and distal tail parts (penetrance 100%). This trait is determined mostly by the mutant mi gene, the expression of which is not affected by modifier genes. However, the degree of mi gene expression, white spotting, on other body parts (wrist, foot, ventral body side, and parietal head part) varied widely in mice obtained from different crosses; penetrance ranged from 0 to 100%. The results obtained indicate that in these cases, the expression of mi gene was strongly affected by modifier genes. The different frequency of the mi gene effects, in heterozygote offspring obtained from reciprocal crosses, can result from the imprinting of the modifier genes in maternal and paternal gametes.
Insights
The microphthalmia (mi) gene in mice causes unpigmented fingers and tail tips. However, modifier genes influence its expression on other body parts, leading to varied white spotting patterns.
Area of Science:
- Genetics
- Developmental Biology
- Mammalian Genetics
Context:
- The microphthalmia (mi) gene mutation in mice affects coat color and eye development.
- Understanding gene expression and modifier gene effects is crucial in mammalian genetics.
Purpose:
- To investigate the role of the microphthalmia (mi) gene and modifier genes in determining coat color patterns in mice.
- To analyze the penetrance and expressivity of the mi gene across different genetic backgrounds.
Summary:
- Mice heterozygous for the microphthalmia (mi) mutation (mi/+) consistently showed unpigmented fingers and distal tail parts (100% penetrance), indicating primary control by the mi gene.
- Expression of the mi gene, resulting in white spotting on other body areas, varied significantly (0-100% penetrance) depending on the genetic background, suggesting strong influence from modifier genes.
- Reciprocal crosses revealed differences in mi gene effects, potentially due to imprinting of modifier genes in parental gametes.
Impact:
- This study highlights the complex interplay between a primary mutant gene and modifier genes in shaping phenotypic outcomes.
- Findings contribute to understanding genetic variation and the mechanisms of gene-environment interactions in mammals.
- The results provide insights into the potential role of genomic imprinting in modulating gene expression and inheritance patterns.