Isolation of a Xanthomonas oryzae pv. oryzae flagellar operon region and molecular characterization of flhF

An 8.1-kb DNA fragment from Xanthomonas oryzae pv. oryzae that contains six open reading frames (ORF) was cloned. The ORF encodes proteins similar to flagellar proteins FlhB, FlhA, FlhF, and FliA, plus two proteins of unknown function, ORF234 and ORF319, from Bacillus subtilis and other organisms. These ORF have a similar genomic organization to those of their homologs in other bacteria. TheflhF gene product, FlhF, has a GTP-binding motif conserved in its homologs. Unlike its homologs, however, X. oryzae pv. oryzae FlhF carries two transmembrane-like domains. Insertional mutations of theflhF gene with the omega cassette or the kanamycin resistance gene significantly retard but do not abolish the motility of the bacteria. Complementation of the mutants with the wild-type flhF gene restored the motility. The X. oryzae pv. oryzae FlhF interacts with itself; the disease resistance gene product XA21; and a protein homologous to the Pill protein of Pseudomonas aeruginosa, XooPilL, in the yeast two-hybrid system. The biological relevance of these interactions remains to be determined.

Betaine aldehyde dehydrogenase from rat liver mitochondrial matrix

An NAD-linked aldehyde dehydrogenase which in addition to aliphatic and aromatic aldehydes, metabolizes aminoaldehydes and betaine aldehyde, has been purified to homogeneity from male Sprague-Dawley rat liver mitochondria. The properties of the rat mitochondrial enzyme are similar to those of a rat liver cytoplasmic betaine aldehyde dehydrognase and the human cytoplasmic E3 isozyme. The primary structure. of four tryptic peptides were also similar; only one difference in primary structure was observed. The close similarity of properties of the cytoplasmic with the mitochondrial form suggest that the cytoplasmic and mitochondrial betaine aldehyde dehydrogenase may be coded for by the same nuclear gene. Investigation of the mitochondrial form by isoelectric focusing resulted in visualization of multiple forms, different from those seen in the cytoplasm suggesting that the enzyme may be processed in the mitochondria.

Mesangial uptake and processing of macromolecules in rats with diabetes mellitus

The uptake and processing of colloidal carbon by the glomerular mesangium was studied in an attempt to determine whether abnormal mesangial function occurs in rats with longstanding streptozotocin-induced diabetes mellitus. The chronically diabetic rats were considerably smaller than their normal littermates receiving a similar dose of colloidal carbon based upon body weight. Thus, further control groups, animals weight-matched with the diabetic rats (younger rats) and littermates of the diabetic rats given the mean quantity of colloidal carbon administered to the diabetic rats, were included. Quantitative evaluation of renal tissues indicated that younger rats have more avid mesangial uptake of colloidal carbon from the circulation and more rapid processing of these macromolecules through the mesangium than the other groups studied. These quantitative studies did not demonstrate any marked impairment in diabetic rats in the over-all capacity of their mesangium to take up and process colloidal carbon when compared with the two groups of littermate nondiabetic animals. However, in those areas of the mesangium thickened by the diabetic process large aggregated of carbon accumulated and persisted over the 6-week period of the study. It appears, therefore, that those areas of the mesangium in diabetic rats with pathologic changes consequent to the diabetic state have significant functional impairment.

An outbreak of infections caused by strains of Staphylococcus aureus resistant to methicillin and aminoglycosides. I. Clinical studies

In a 22-month period, strains of Staphylococcus aureus resistant to methicillin and multiple aminoglycosides, (designated MARS) were recovered from 108 inpatients with nosocomial infections at a hospital in the midwestern United States. Sixty-six of these patients were staying in a burn unit, and 42 were on other hospital wards. Among the patients with burns, MARS were recovered from the burn wounds of 64%; 32% of the patients with burns had MARS bacteremia. The patients without burns were age-matched with patients with nosocomial infections caused by antibiotic-susceptible strains of S. aureus. Patients from whom MARS were isolated had a longer mean hospital stay (79.6 days vs. 36.9 days; P less than 0.01), developed infection later (26.5 days vs. 13.5 days after admission; P less than 0.01), and had received antibiotic therapy before infection more often (81% vs. 38% of patients; P less than 0.01) than patients in the comparative population. Types of infection and incidences of death and bacteremia were similar in the two groups. Antibiotic-resistant strains of S. aureus may cause serious infections and significant mortality.