Gene expression in Brassica campestris showing a hypersensitive response to the incompatible pathogen Xanthomonas campestris pv. vitians

Xanthomonas campestris pv. vitians, a pathogen of lettuce, elicits a hypersensitive response within 12 hours of inoculation into Brassica leaves, characterized by tissue collapse, loss of membrane integrity, vein blockage and melanin production. In contrast, the compatible pathogen, X. c. pv. campestris, has no visible effects on leaves for 48 hours, after which inoculated areas show chlorosis which eventually spreads, followed by rotting.mRNA was prepared from leaves inoculated with suspensions of both pathovars or with sterile medium up to 24 hours following inoculation. In vitro translation of total and poly A⁺ RNA in rabbit reticulocyte lysate in the presence of ³⁵S methionine followed by separation of the polypeptide products by 2D-PAGE, allowed comparison of the effects of these treatments on plant gene expression. Major changes in gene expression were observed as a consequence of the inoculation technique. In addition, after inoculation with X. c. vitians, up to fifteen additional major polypeptides appeared or greatly increased by four hours. Some of these had disappeared by nine hours and several more had appeared. No major polypeptides disappeared or decreased greatly in intensity following inoculation with X. c. vitians.     

Sequence homology in the metalloproteins; purple acid phosphatase from beef spleen and uteroferrin from porcine uterus

The primary structures of purple acid phosphatase and uteroferrin, two iron-binding glycoproteins isolated from beef spleen and porcine uterine fluids, respectively, have been examined by a combination of tandem mass spectrometry and classical Edman sequencing methods. Reported here are amino acid sequence data covering more than 90% of the primary structures for these two proteins. The sequence data reveal an unexpectedly high degree of homology, greater than 90%, for these two proteins.     

Pseudomonas aeruginosa outer membrane protein F produced inEscherichia coli retains vaccine efficacy

Pseudomonas aeruginosa outer membrane protein F was purified by extraction from polyacrylamide gels of cell envelope proteins of anEscherichia coli strain expressing the cloned gene for protein F. Antisera directed against protein F purified fromP. aeruginosa PAO1 reacted with thisE. coli strain by immunofluorescence assay and immunoblotting, whereas these antisera were nonreactive withE. coli strains lacking thePseudomonas protein F gene. The protein F purified from thisE. coli strain was used to immunize mice by intramuscular injection of 10 µg of protein F preparation on days 1 and 14, followed by burn and challenge of the mice on day 28. As compared with control mice immunized withE. coli K-12 lipopolysaccharide, immunization with theE. coli-derived protein F afforded significant protection against subsequent challenge with heterologous Fisher-Devlin immunotype 5 and 6 strains ofP. aeruginosa. Antisera from mice immunized with theE. coli-derived protein F reacted at bands corresponding to protein F and 2-mercaptoethanol-modified protein F upon immunoblotting against cell envelope proteins of the PAO1, immunotype 5, and immunotype 6 strains ofP. aeruginosa and theE. coli strain containing the cloned F gene, but failed to react at these sites in anE. coli strain lacking the F gene. These data demonstrate thatP. aeruginosa protein F produced inE. coli through genetic engineering techniques retains its vaccine efficacy in the complete absence of anyP. aeruginosa lipopolysaccharide.