THE MURINE SPAM1 GENE - RNA EXPRESSION PATTERN AND LOWER STEADY-STATELEVELS ASSOCIATED WITH THE RB(6.16) TRANSLOCATION

Recently we mapped the murine Spam1 gene to the proximal region of chr omosome 6 (MMU 6). Based on the map location and physiological charact eristics of its encoded sperm antigen, the gene is an attractive candi date for the sperm dysfunction seen in Rb(6.16) translocation heterozy gotes and the reduced fertility of homozygotes. We have analyzed the e xpression of Spam1 mRNA in normal and Rb(6.16) mice. The expression of Spam1 mRNA was found to be: 1) tissue specific; it is expressed exclu sively in testis; and 2) developmentally regulated, with a haploid exp ression. Notably, the steady-state mRNA level of Spam1 in Rb(6.16) hom ozygotes was 25-30% of that in chromosomally normal consomic mice and those homozygous for Rb(2.8) (7.18). In Rb(6.16) and Rb(6.15) heterozy gotes the levels were 61% and 66% of the normal. Studies are currently under way to determine the protein levels and gene structure of Spam1 , to detect the underlying cause of the mRNA reduction associated with these translocations. (C) 1997 Wiley-Liss, Inc.