GENETIC-MAPPING OF 20 NOVEL EXPRESSED SEQUENCE TAGS FROM MIDGESTATIONMOUSE EMBRYOS SUGGESTS CHROMOSOMAL CLUSTERING

Current knowledge of genes that regulate pattern formation and differe ntiation processes during mammalian embryonic development is limited. In an effort to isolate developmentally relevant genes, 20 novel, end- sequenced cDNAs selected from a Day 10.5 post-coitum mouse embryo libr ary were genetically mapped in intersubspecific backcross mice. Eleven of 20 cDNA clones mapped to three mouse autosomes (Chr 5, 11, and 14) , a result that was unlikely (P < 0.03) if the distribution of genes e xpressed in embryos is random within the mouse genome. Several clones were candidates for mouse developmental mutations by virtue of genetic colocalization and concordance of embryonic expression patterns with the distribution of defects in mutant mice: Estm11 was a candidate for the mouse mutation wabbler-lethal (wl), since Estm11 mapped in the vi cinity of wl on mouse Chr 14 and was expressed in those regions of emb ryonic brain that exhibit axonal degeneration in wt. End-sequence anal ysis, genetic mapping, and in situ hybridization appeared to be an eff ective combination of methods for identification and characterization of genes with potential regulatory functions during mammalian embryoge nesis. (C) 1997 Academic Press.