Petko Petkov

Chromosome-wide Mapping of Recombination Activity

 

Our goal is to generate the first high-resolution maps of mammalian recombination activity for an entire chromosome as a representative of the genome as a whole, including the variation in hotspot location and activity within and between species, and how this differs in F1 animals from reciprocal crosses and between male and female meiosis. For this we are mapping recombinants arising in 3000 meioses from each of six genetic crosses at under 50-Kb resolution, enabling us to distinguish individual hotspots and detect activities as low as 0.03 cM/hotspot. These data will go far in helping us understand mammalian recombination as a biological process as well as relationships between parameters of recombination and other aspects of chromosome dynamics.

Specifically we are:

  1. Mapping the location of every crossover on Chromosome 11 arising in six genetic crosses, 3000 offspring each for a total of 18,000 meioses, at under 50 kb resolution. Four of the crosses are female F1 hybrids created in a daisy-chain design (C57BL/6J x PWD/PhJ x WSB/EiJ x CAST/EiJ x C57BL/6J) and then backcrossed to C57BL/6J. F1 male hybrids from crosses of C57BL/6J x PWD/PhJ and WSB/EiJ x CAST/EiJ are also being backcrossed to C57BL/6J. Whenever possible, equal numbers of meioses are derived from F1 animals created by reciprocal crosses of the original parents (AxB and BXA). This design is optimal for gathering data on genetic variability, sex specificity, and possible imprinting effects in these crosses.

  2. Using these data, we are analyzing the strain, sex and cross direction specificity of the location, distribution and activity of the recombination hotspots along the length of Chromosome 11. For understanding evolutionary processes, we are also providing a consensus map of Chromosome 11 hotspots across subspecies.

  3. Making the 18,000 backcross DMA samples available to the scientific community via a repository, and the 3000 SNP assays that are being newly developed on Chromosome 11 are being posted on our website and made available to others for QTL and gene mapping studies.