Figure 3.

Map locations of lethal mutations. The proximal region of Chr. 5 is depicted as a horizontal line, with the centromere (filled circle) on the left. The region spanned by the Rw inversion is indicated above; its breakpoints are within Dpp6 proximally and near c-kit distally. Map positions (in megabases, accordingly to mouse genome Build 33) are indicated. Microsatellite loci are abbreviated by exchanging the prefix “M” for “D5Mit.” Deletions are indicated as horizontal rectangles, either solid or striped, and are color coded with the locus at which they were induced (red) Dpp6; (blue) Hdh; (green) Qdpr. The amount of DNA known to be absent in each deletion is spanned by the rectangles. The thin lines extending from the ends of the rectangles indicate the regions in which the deletion breakpoints reside. Those deletions that have been converted into stocks of mice are represented by solid rectangles, and associated allele names are given (the bracketed text corresponds to superscripting). New deletions at the Qdpr locus existing only in ES cells are represented by the striped or unfilled rectangles. In this latter case, the number of independent ES cell lines containing a particular class of deletion (currently indistinguishable with the markers used in this study) is indicated on the right. The intervals containing certain lethal mutations (abbreviated as “L. #”) are bracketed at the bottom of the map. Those that were deletion mapped are color coded. Those that were recombination mapped are in black. The yellow-shaded “ES cell haplolethal zone” is an interval that connot be deleted in ES cells. Originally described by Schimenti et al. (2000), its proximal end has been refined as described in the text, and the distal end was also refined by further analysis of deletions centered at the Gabrb1 (data not shown). (Shh) Sonic hedgehog homolog.