NORMAL DEVELOPMENT OF MICE CARRYING A NULL MUTATION IN THE GENE ENCODING THE L14 S-TYPE LECTIN

The L14 lectin is a 14x10(3) M(r) carbohydrate binding protein belongi ng to the family of S-type lectins. The pattern of-expression of this protein during mouse embryogenesis suggests that it may have multiple roles during pre- and post-implantation development. Using the techniq ue of homologous recombination in embryonic stem cells, we have introd uced a null mutation in the gene encoding the L14 lectin and generated a strain of mice carrying the mutant allele. We report here that homo zygous mutant animals that lack the L14 lectin develop normally and ar e viable and fertile. The absence of any major phenotypic abnormalitie s in these mutant animals suggests that other protein(s) potentially c ompensate for the absence of the L14 lectin. Here we show that a relat ed protein termed L30, a lectin that has carbohydrate binding specific ity similar to that of L14, is present in the same embryonic cell popu lations as L14 at the time of implantation, suggesting that the two S- type lectins may be capable of functional substitution at this early s tage of embryogenesis.