ANALYSIS OF CDNA SEQUENCES FROM MOUSE TESTIS

Few mammalian proteins involved in chromosome structure and function d uring meiosis have been characterized. As an approach to identify such proteins, cDNA clones expressed in mouse testis were analyzed by sequ encing and Northern blotting. Various cDNA library screening methods w ere used to obtain the clones. First, hybridization with cDNA from tes tis or brain allowed selection of either negative or differentially ex pressed plaques. Second, positive plaques were identified by screening with polyclonal antisera to prepubertal testis nuclear proteins. Most clones were selected by negative hybridization to correspond to a low abundance class of mRNAs. A PCR-based solid-phase DNA sequencing prot ocol was used to rapidly obtain 306 single-pass cDNA sequences totalin g more than 104 kb. Comparison with nucleic acid and protein databases showed that 56% of the clones have no significant match to any previo usly identified sequence. Northern blots indicate that many of these n ovel clones are testis-enriched in their expression. Further evidence that the screening strategies were appropriate is that a high proporti on of the clones which do have a match encode testis-enriched or meios is-specific genes, including the mouse homolog of a rat gene that enco des a synaptonemal complex protein.