Evolutionary relationships between the t and H-2 haplotypes in the house mouse

Area of Science:

• Immunogenetics
• Molecular Biology
• Evolutionary Biology

Background:

• The H-2 complex in mice encodes critical immune system molecules.
• T haplotypes are specific genetic arrangements within the H-2 complex.
• Previous studies defined six complementation groups for t haplotypes.

Purpose of the Study:

• To characterize H-2 haplotypes in 33 mouse strains carrying t haplotypes.
• To identify novel complementation groups within t haplotypes.
• To investigate the evolutionary history and antigenic relationships of t chromosomes.

Main Methods:

• Serological typing using monoclonal and polyclonal antibodies against H-2 class I and class II antigens.
• Analysis of K, D, A, and E loci alleles.
• Identification of mutations affecting E molecule expression.

Main Results:

• Identified H-2 haplotypes and alleles for 33 mouse strains, including eight new complementation groups.
• Discovered a mutation preventing E molecule expression in 19 of the 33 strains (E0 mutation).
• Established serological relatedness among H-2 haplotypes, forming a pedigree suggesting ancient origins predating species divergence.

Conclusions:

• T haplotypes share unique antigenic determinants, indicating a common, ancient evolutionary origin.
• The E0 mutation is ancient and present across different evolutionary branches of t chromosomes.
• The study provides insights into the evolutionary history of mouse H-2 complex and t chromosomes.