Deoxyribonucleic Acid-Deoxyribonucleic Acid Hybridization Analysis of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus

Abstract

Deoxyribonucleic acids (DNAs) were isolated and purified from 20 strains of Actinobacillus actinomycetemcornitans, 6 strains of Haemophilus aphrophilus, 2 strains of Haemophilus paraphrophilus, 2 strains of Haemophilus pleuropneumoniae, 2 strains of Haemophilus paraphrohaemolyticus, 2 strains of Haemophilus injhenzae, and 1 strain each of Actinobacillus lignieresii, Actinobacillus suis, Haemophilus aegyptius, Haemophilus parainfluenzae, and Haemophilus parahaemolyticus. The guanine-plus-cytosine contents of the DNAs were determined, and they agreed closely with previous estimates. DNA-DNA hybridization analyses revealed that all of the strains identified as A . actinomycetemcomitans were at least 69% homologous to DNA probes from two A . actinomycetemcomitans strains (strains NCTC 9710T [T = type strain] and Y4). The H . aphrophilus and H . paraphrophilus strains were homologous to the two A . actinomyceterncomitans probes at levels of 25 to 37%. The DNAs of all A . actinomycetemcomitans strains were homologous to a DNA probe from H . aphrophilus strain NCTC 5906 at levels of 30 to 39%. The two strains of H . paraphrophilus tested were homologous to the H . aphrophilus probe at levels of 73 and 77%, indicating a very close relationship between these groups of organisms. H. parainfluenzae strain ATCC 9796 DNA seemed to be homologous to the H . aphrophilus and A . actinomycetemcomitans probes at low but significant levels (12 to 16%). All of the other strains of haemophili and actinobacilli tested gave 10% or less homology with the three test probes.

Experimental error in DNA–DNA pairing: a survey of the literature

“…The plot ( Fig. 1) from the data of Potts & Berry (1983) showed greater error with higher per cent pairing; this was not always seen, however (see Fig. 2).…”

“…Error seemed to be largely independent of the degree of pairing, although there was some evidence for an increase in error at high homology values in Potts & Berry's (1983) data (Fig. 1).…”

“…Few papers state both the number of replications and standard deviation associated with each result. The study of Potts & Berry (1983) is one of the few which lists these. Also, conclusions are frequently drawn from incomplete sets of data, and this leads to difliculties in obtaining with confidence the underlying taxonomic structure, particularly when there are only a few reference strains (Hartford & Sneath 1988).…”

Investigation of the Actinobacillus actinomycetemcomitans genome by pulsed field gel electrophoresis

“…The size of the genome was calculated using two laboratory strains and the reference strain DNAs digested with rare cutting endonucleases. Since the G+C% of DNA is rather low, 44.9 to 46.6 (22), endonucleases recognizing an 8 nucleotide GC rich site, such as NotI (GC/ GGCCGC), 5^1 (GGCCN/NGGCC) or Ssel 8387 (CCTGCA/GG) have a low frequency cleavage. Fig.…”

“…Typing strains of A. actinomycetemcomitans based on polysaccharide antigens (20,35) discriminates five serogroups a, b, c, d and e (24). Characterization at the DNA level is possible by DNA-DNA hybridization (22). Genomic methods, by restriction endonuclease analysis (5,8,10,34) or by polymerase chain reaction (6,7,33) improve the identification and discrimination of strains of A. actinomycetemcomitans, but have only been used for epidemiological studies.…”