Immunoblots using bovine antibody against Haemophilus somnus as the primary antibody consistently identified 31-, 40- and 78-kDa proteins in Sarkosyl-insoluble extracts of H. somnus. A genomic library of H. somnus 8025 DNA was constructed in plasmid pUC19, and 45 recombinants expressed proteins which were recognized by bovine antiserum in Western blots (immunoblots). Ten of the recombinants expressing a 31-kDa protein caused the lysis of bovine erythrocytes. Restriction endonuclease mapping indicated that the hemolytic recombinants shared an approximately 1.7-kb BglII fragment. Southern blot analysis using the BglII fragment as a probe revealed homology among the recombinants and the presence of an identically sized BglII fragment in the chromosome of all H. somnus isolates tested. Sequence analysis indicated the presence of an 822-bp open reading frame within the 1.7-kb BglII fragment. Deletion of this open reading frame resulted in the loss of hemolytic activity and protein expression in recombinant Escherichia coli, suggesting the possible role of the 31-kDa protein as a hemolysin. An amino acid sequence deduced from the DNA sequence shared homology with outer membrane protein A of E. coli, Salmonella typhimurium, and Shigella dysenteriae, with P6 of Haemophilus influenzae, and with PIII of Neisseria gonorrhoeae. An amino acid analysis of the recombinant 31-kDa protein agreed with the amino acid composition deduced from the DNA sequence.

Amino Acid Sequence↗

PubMed1990

Precise excision and instability of the transposon Tn5 in Pseudomonas aeruginosa.

Excision of the transposon Tn5 from sites of insertion in plasmid DNA was shown to occur at high frequency in Pseudomonas aeruginosa. Plasmids with Tn5 insertions conjugated poorly into P. aeruginosa and adversely affected growth compared to the respective parental plasmids. The kanamycin-resistance phenotype of Tn5 was expressed poorly in P. aeruginosa and kanamycin-sensitive strains were common during the manipulation of the P. aeruginosa transconjugants. Examination of plasmid DNA isolated from kanamycin-sensitive P. aeruginosa transconjugants revealed excision of Tn5 sequences. A plasmid containing a selectable marker (mercury resistance) inactivated by a Tn5 insertion was constructed, and Tn5 excised precisely, permitting the expression of the mercury-resistance marker at high frequency (10(-3) in P. aeruginosa and at the expected low frequency (10(-7] in Escherichia coli. The recombinational mechanism that promotes frequent Tn5 excision in P. aeruginosa operated in the absence of the P. aeruginosa recA gene product. Fragments of Tn5 were also examined for excision and instability in P. aeruginosa. A plasmid containing the terminal 485 bp of inverted repeat sequences from Tn5, but lacking the transposase or kanamycin-resistance genes, also showed precise excision of Tn5 DNA at high frequency (10(-2] in P. aeruginosa. Unlike plasmids containing a complete Tn5 insertion, this plasmid transferred to P. aeruginosa at normal frequencies and growth of the host was not severely impaired. In contrast, plasmids containing either IS50 element transferred to P. aeruginosa at greatly reduced frequencies, and transconjugants containing the IS50R element (which contains the active transposase gene) were small and especially difficult to maintain. P. aeruginosa transconjugants harbouring a plasmid containing only the DNA between the IS50 elements (which included the kanamycin-resistance gene) were of normal size and stably maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗

PubMed1982

Selective arterial medial injury fails to produce intimal hyperplasia in experimental animals.

The hypothesis was tested, in rats and rabbits, that selective medial injury may lead to arterial intimal hyperplasia. Lesions were produced by passage of a micro-suture through the arterial wall without penetration to the lumen, or controls in which the suture did penetrate. Vessels were examined histologically at intervals up to 2 weeks after suturing. Only vessels with penetrating sutures developed intimal hyperplasia, suggesting that medial injury alone is insufficient for the production of arteriosclerosis.

Animals↗

PubMedDate not supplied

In vitro synthesis of DNA, protein, and lipids by the de-endothelialized rabbit aorta.

The uptake of [3H] leucine, [3H] thymidine, [14C] acetate, and [14C] mevalonic acid by aortic intima media from normal rabbits and from rabbits subjected to a single balloon de-endothelialization as measured 6 days, 2 months, and 4 months after treatment to determine how long the injury-induced stimulation of incorporation of these precursors into tissue components persisted beyond 6 days, the time of maximum proliferative response of the smooth muscle cells. We found that [3H] thymidine incorporation (indicative of DNA synthesis and the potential for cell proliferation) was about three times greater in the de-endothelialized tissue than in the control tissue 6 days after vessel injury, but that by 2 months it was normal. Labeled leucine incorporation into the de-endothelialized tissue (a measure of protein synthesis) was eight times higher than normal at the time of maximum proliferative response to injury (6 days), and showed no decrease under identical incubation conditions in ballooned tissue obtained 2 months after de-endothelialization; it continued high at 4 months. Both [14C] acetate and [14C] mevalonate uptake into lipids by the aortic tissue were enhanced by the injury; this increased incorporation was still evident at 4 months. Thus, de-endothelialization of the aorta triggers a vessel wall response characterized by augmented protein synthesis and lipogenesis, which persists at least 4 months after injury and at least 2 months after DNA synthesis has normalized.

Animals↗