The random-amplified polymorphic DNA (RAPD) assay was used to generate DNA fingerprints for 16 isolates of "Haemophilus somnus," and one isolate each of "Haemophilus agni," "Histophilus ovis," "ActinobaciUlus seminis," Pasteurella haemolytica, and Escherichia coli. The RAPD assay differentiated among "H. somnus" isolates, which shared similarity coefficients of 0.46 to 1.00 on the basis of pairwise comparisons of RAPD markers produced with nine random decamer primers. Three virulent encephalitic "H. somnus" isolates exhibited identical banding patterns, suggesting a common clonal ancestry. The RAPD assay clearly distinguished between the "H. somnus"-"H. agni"-"H. ovis" group and the other bacterial species tested. The results of the present study suggest that DNA fingerprinting of "H. somnus" isolates by the RAPD assay could be valuable in revealing subspecific divisions within this largely unexplored species.

Body proteins in cats were prelabelled with [14C]valine, and protein degradation was studied in isolated hepatocytes. Amino acids appeared to have a direct inhibitory effect on protein degradation, but the effects were generally smaller than those previously shown in the rat. The amino acid control of protein degradation in the cat differs from that in the rat, as shown by the lack of effects of glutamine, asparagine, arginine or methionine in cat hepatocytes. This may be related to the unique features of protein metabolism of this species. NH4Cl, leupeptin and amino acids, which suppress lysosomal protein degradation by different mechanisms, caused less than 30% inhibition of protein degradation when used at the optimum concentrations reported for the rat. The ability of the lysosomal system to respond to nutritional deprivation is apparently lower in the cat than in the rat.