Ornithine transcarbamylase deficiency in spf and spf-ash mice: genes, mRNAs and mRNA precursors.

Two ornithine transcarbamylase-deficient mice are available, the spf with a variant enzyme and spf-ash with a markedly decreased enzyme protein. Genomic DNA, mRNA and the nuclear precursors for the enzyme in these mutants were analyzed. Southern blot analysis of genomic DNA showed no abnormality in the mutant mice. Blot analysis of hepatic mRNA revealed a slight decrease (67% of control) in spf and a marked decrease (12% of control) in spf-ash; no difference in size was found among the control and the mutant mice (about 1.8 kb). Blot analysis of nuclear mRNA precursors (greater than 25, approximately 9.0 and 4.0 kb) showed no significant difference in size and amount among the control, spf and spf-ash. These results suggest that ornithine transcarbamylase deficiency in the spf-ash results from a mutation, which to some extent affects mRNA processing.