Differential expression of novel abundant and highly regionalized mRNAs ofthe canine epididymis

Three novel gene products have been cloned by differential screening of a d og epididymis cDNA library as part of a global appraisal of specific gene e xpression in the epididymis. The predicted proteins were provisionally name d CE8-CE10 (for canine epididymal gene products 8-10). Northern blot analys es and in situ transcript hybridization confirmed that the cDNAs were all d erived fi-om tissue-specific, moderately to highly abundant mRNAs of the ep ididymal epithelium, showing a distinct regionalized expression pattern wit hin the epididymal duct. Their sequences predict (i) a novel 19 kDa member of the Ly-6-domain protein superfamily (CE8), (ii) an approximately 30 kDa protein with multiple membrane-spanning regions (CE9), and (iii) a novel ap proximately 13 kDa single whey acidic protein domain protein (CE10). Closel y related, cross-hybridizing gene products were abundant in the epididymis of stallions and bulls, but not in rodents or men. Changes in mRNA frequenc y were observed that specifically correlated with a cryptorchid situation a nd with the age of the dogs. Gene products restricted to the caput epididym idis were affected by both conditions, while those with a wider regional di stribution were not.