Phenotypic characteristics of thermotolerantCampylobacter from human and animal sources

Five reference strains and 314 field strains ofCampylobacter growing at 42°C, but not at 25°C, were characterized by tests of hippurate hydrolysis and sensitivity to nalidixic acid, to metronidazole, and to 2,3,5-triphenyltetrazolium chloride (TTC). All strains but seven were TTC-resistant by the disc test used. Of 168 human isolates, 87% hydrolyzed hippurate; three of these strains were nalidixic acid-resistant. Also hippurate-positive were all 23 strains from ovine abortion, 79% of 43 avian strains, two of six bovine isolates, and one of two strains of equine origin. Seventy-two porcine strains were all hippurate-negative. Metronidazole sensitivity was found to be a variable property in hippurate-positive strains, although present in all but four hippurate-negative strains. A group of eight nalidixic acid-resistant, hippurate-negative isolates of porcine and bovine origin probably represent a new group ofCampylobacter.     

Base composition of deoxyribonucleic acid isolated from mycobacteria

Guanine plus cytosine values of deoxyribonucleic acid derived from 30 cultures representing 14 mycobacterial species or varieties are presented. These data provide impressive reasons for maintaining the separation between the genera Corynebacterium and Mycobacterium; no conclusions can be arrived at from these data with respect to the Nocardia-Mycobacterium relationship. A bimodal clustering, in terms of guanine plus cytosine composition, is apparent within the genus Mycobacterium. In general, all members of any single phenetic species appear to fit into one or another of these clusters. The phenetic separation of species is, in some cases, confirmed by separation in terms of guanine plus cytosine values. The bimodal separation of guanine plus cytosine values within the genus Mycobacterium does not correspond to a division of the species into slow and rapid growers; it thus provides no justification for splitting Mycobacterium into two genera, composed of slow and rapid growers. This is not to say that such a split would not be useful, only that these data do not contribute to such a decision. Any further attempts to correlate phenetic classification with properties of mycobacterial deoxyribonucleic acid will require more specific techniques, such as molecular hybridization.     

Base sequence homology and renaturation studies of the deoxyribonucleic acid of extremely halophilic bacteria

The genetic relatedness among various strains of halophilic bacteria has been assessed by deoxyribonucleic acid-deoxyribonucleic acid (DNA-DNA) duplex formation and ribosomal ribonucleic acid (RNA) hybridization. All of the strains of extremely halophilic rods are closely related, and the extent of divergence of base sequence is similar for the major and minor DNA components. Parallel experiments with ribosomal RNA revealed a relationship between the extremely halophilic rods and cocci and a more distant relationship to moderate halophiles and to a photosynthetic extreme halophile. Renaturation studies of halophile DNA exclude the possibility that the satellite DNA represents multiple copies of a small episomal element. The kinetics of DNA renaturation show that the genome size of the extreme and moderate halophiles is similar to that of Escherichia coli.     

Estimation of primary sequence homology from amino acid composition of evolutionary related proteins

The amino acid compositions of many of the known sequenced proteins were compared to determine if a relationship exists between the amino acid composition and the amount of sequence homology of these proteins. For this purpose, a function, the composition divergence, was defined. A computer program based on relatively simple assumptions has been successfully used to simulate the data distribution found in comparing composition divergence with the sequence dissimilarity. From this characterization of known proteins, it is possible to predict the sequence homology of unsequenced proteins, based on amino acid composition comparisons. The power and limitations of this technique are discussed.     

Base composition, size and sequence similarities of genoma deoxyribonucleic acids from clinical isolates of Pseudomonas putrefaciens

The mean base compositions of DNA from 27 strains of Pseudomonas putrefaciens, P. rubescens and P. piscicida ranged from 43-4 to 53-2 mol% GC with genome sizes from 3.04 X 10(9) to 4.23 X 10(9) daltons. On the basis of in vitro DNA-DNA binding, estimated spectrophotometrically from initial renaturation rates, P. putrefaciens strains were heterogenous in the extent to which they shared similar nucleotide sequences, and were divided into four DNA homology groups. The DNA characteristics of strains in these groups correlated with several biochemical characteristics that facilitated identification of clinical isolates of P. putrefaciens. The two species P. putrefaciens and P. rubescens appear to be synonymous and none of the four groups of P. putrefaciens was related in DNA sequences to P. pisicida. Pseudomonas putrefaciens should theretofore be retained as a single species and characteristics for identifying the various groups within the species are listed.     

Amino acid sequence homology between bovine and human platelet proteins

The complete amino acid sequence of bovine platelet factor 4 (PF-4) was determined. Comparison of the 88 residue bovine protein with its 70 residue human counterpart indicated 73% homology. There is 53% homology between this bovine protein and another human platelet protein, beta-thromboglobulin (beta-TG). These heparin binding proteins share greatest homology around a lysine-rich octa-peptide near the carboxy-terminus which is the putative heparin binding domain. Graphic comparison of these proteins suggests that a point mutation at position 55 (human PF-4 numbering) could cause a significant difference among the folding properties of these 3 proteins and might be critical for their different heparin binding properties.     

Nucleotide sequence homology between the heat-labile enterotoxin gene of Escherichia coli and Vibrio cholerae deoxyribonucleic acid.

Isolated deoxyribonucleic acid fragments encoding the heat-labile enterotoxin of Escherichia coli were used to probe for homologous sequences in restricted whole-cell deoxyribonucleic acid from Vibrio cholerae. Significant sequence homology between the heat-labile enterotoxin gene and V. cholerae deoxyribonucleic acid was demonstrated, and apparent differences were observed in the organization of the cholera toxin gene among different strains of V. cholerae.     

Molecular cloning of complementary deoxyribonucleic acid for an androgen-regulated epididymal protein: sequence homology with metalloproteins

Acidic epididymal glycoprotein (AEG) is a 31,000 molecular weight secretory protein of the rat epididymis. Screening of a rat epididymal cDNA library with affinity-purified AEG antiserum yielded cDNA for AEG. Identity of the clones was verified by comparison of amino acid sequence of the purified protein with the sequence derived from the nucleotide sequence of the cDNA isolates. Two classes of AEG cDNA, approximately 1500 base pairs (bp) and 950 bp in length, differed by 538 bp in the 3'-untranslated region and by four single nucleotide mismatches, one of which was in the coding region. Northern blot hybridization of epididymal RNA revealed two species of AEG mRNA, corresponding in length to each type of cDNA. Analysis of RNA from individual animals provided evidence that the two mRNA species are the products of allelic genes. In vivo studies demonstrated that the level of total AEG mRNA is regulated by androgen. Amino acid sequence homology of AEG with metal-binding domains of several proteins suggests that AEG is a metalloprotein.     

Base composition of deoxyribonucleic acid of the temperature-sensitive kanamycin-resistant R factor, Rts1

The buoyant density of deoxyribonucleic acid (DNA) from the temperature-sensitive R factor, Rts1, was determined by CsCl density-gradient centrifugation. Rts1 was found to consist of a single species of DNA of density 1.705 g/cm(3), which corresponds to a base composition of 45% guanine plus cytosine. This value is distinct from the densities previously reported for other R factors, suggesting that Rts1 represents a new molecular class of R factors.     

Amino acid sequence homology between rat and human C-reactive protein.

The rat serum protein that undergoes Ca2+-dependent binding to pneumococcal C-polysaccharide and to phosphocholine residues, and that is evidently a member of the pentraxin family of proteins by virtue of its appearance under the electron microscope, has been variously designated as rat C-reactive protein (CRP) [de Beer, Baltz, Munn, Feinstein, Taylor, Bruton, Clamp & Pepys (1982) Immunology 45, 55-70], 'phosphoryl choline-binding protein' [Nagpurkar & Mookerjea (1981) J. Biol. Chem. 256, 7440-7448] and rat serum amyloid P component (SAP) [Pontet, D'Asnieres, Gache, Escaig & Engler (1981) Biochim. Biophys. Acta 671, 202-210]. The partial amino acid sequence (45 residues) towards the C-terminus of this protein was determined, and it showed 71.7% identity with the known sequence of human CRP but only 54.3% identity with human SAP. Since human CRP and SAP are themselves approximately 50% homologous, the level of identity between the rat protein and human SAP is evidence only of membership of the pentraxin family. In contrast, the much greater resemblance to human CRP confirms that the rat C-polysaccharide-binding/phosphocholine-binding protein is in fact rat CRP.     

Uronic acid sequence in alginate from different sources

Alginate may be considered as a block co-polymer of D-mannuronic and L-guluronic acids, and consists of three types of blocks: homopolymeric blocks of mannuronic acid (MM) and of guluronic acid (GG), and blocks with an alternating sequence (MG). The block composition of alginates has been characterized by a simple chemical method involving partial hydrolysis with acid, followed by fractional precipitation of the acid-resistant part of the alginate. Alginates from eleven different species of brown algae have been examined and, for five species, alginates from different tissues have been compared. The results indicate that young tissue is rich in MM blocks, and that the difference between the alginates from different species is mainly due to the alginates from the older parts of the plants. Extracellular alginates from two types of bacteria have been examined.