RESUMO
The physical and functional organizations of a genome are correlated outcomes of evolution. Inbred strains of mice provide a unique opportunity for exploring these relationships, representing as they do, diverse genomes originally separated by millions of generations that were then scrambled in the laboratory and subjected to intense selection during inbreeding to homozygosity. Here we show that the resulting pattern of chromosome organization includes regional domains of functionally related elements that promote the co-inheritance and survival of compatible sets of alleles. There are also patterns of linkage disequilibrium between domains on separate chromosomes; these are distinctly non-random and form networks with scale-free architecture. The strong conservation of gene order among mammals suggests that the domains and networks we find likely characterize all mammals, and possibly beyond.
Assuntos
Genoma/genética , Camundongos Endogâmicos/genética , Animais , Evolução Molecular , Ordem dos Genes , Desequilíbrio de Ligação , Camundongos , Seleção GenéticaRESUMO
We present an analysis of crossover interference in the mouse genome, on the basis of high-density genotype data from two reciprocal interspecific backcrosses, comprising 188 meioses. Overwhelming evidence was found for strong positive crossover interference with average strength greater than that implied by the Carter-Falconer map function. There was some evidence for interchromosomal variation in the level of interference, with smaller chromosomes exhibiting stronger interference. We further compared the observed numbers of crossovers to previous cytological observations on the numbers of chiasmata and evaluated evidence for the obligate chiasma hypothesis.