Genetic organisation of the capsule transport gene region from Haemophilus paragallinarum

The region involved in export of the capsule polysaccharides to the cell surface of Haemophilus paragallinarum was cloned and the genetic organisation determined. Degenerate primers designed from sequence alignment of the capsule transport genes of Haemophilus influenzae, Pasteurella multocida and Actinobacillus pleuropneumoniae were used to amplify a 2.6 kb fragment containing a segment of the H. paragallinarum capsule transport gene locus. This fragment was used as a digoxigenin labelled probe to isolate the complete H. paragallinarum capsule transport gene locus from genomic DNA. The sequence of the cloned DNA was determined and analysis revealed the presence of four genes, each showing high homology with known capsule transport genes. The four genes were designated hctA, B, C and D (for H. paragallinarum capsule transport genes) and the predicted products of these genes likely encode an ATP-dependent export system responsible for transport of the capsule polysaccharides to the cell surface, possibly a member of a super family designated ABC (ATP-binding cassette) transporters.     

Comparison of Fecal Methanogenic Archaeal Community Between Erhualian and Landrace Pigs Using Denaturing Gradient Gel Electrophoresis and Real-Time PCR Analysis

Erhualian and Landrace breeds are typical genetically obese and lean pigs, respectively. To compare the fecal methanogenic Archaeal community between these two pig breeds, fecal samples from different growth phase pigs were collected and used for PCR-denaturing gradient gel electrophoresis （DGGE） with two primer pairs （344fGC/519r and 519f/915rGC） and real-time PCR analysis. Results showed that a better separation and higher quality of bands pattern were obtained in DGGE proifles using primers 344fGC/519r as compared with primers 519f/915rGC. Sequencing of DGGE bands showed that the predominant methanogens in the feces of Erhualian and Landrace pigs belonged to Methanobrevibacter spp. and Methanosphaera spp. Real-time PCR analysis revealed that there was no signiifcant difference in the numbers of fecal total methanogens between Erhualian and Landrace pigs;however, pig growth phase affected the numbers of 16S rRNA genes of total methanogens and Methanobrevibacter smithii. Dissociation curves of methyl coenzyme-M reductase subunit A （mcrA） gene fragments ampliifed with real-time PCR showed all samples possessed a single peak at 82＆#176;C, which might be associated with M. smithii. Samples from the same growth phase of each breed showed good replicative dissociation curves. The results suggest that the growth phase （including diet factor） other than genotype of pig may affect the fecal methanogenic Archaeal community of pigs.     

DNA: a programmable force sensor

Direct quantification of biomolecular interaction by single-molecule force spectroscopy has evolved into a powerful tool for materials and life sciences. We introduce an approach in which the unbinding forces required to break intermolecular bonds are measured in a differential format by comparison with a known reference bond (here, a short DNA duplex). In addition to a marked increase in sensitivity and force resolution, which enabled us to resolve single-base pair mismatches, this concept allows for highly specific parallel assays. This option was exploited to overcome cross-reactions of antibodies in a protein biochip application.     

Field Trials with a New Genetically Engineered Vaccine for Protection Against Progressive Atrophic Rhinitis in Pigs

Bording, A., K. Nymark, E. Smidt: Field trials with a new genetically engineered vaccine for protection against progressive atrophic rhinitis in pigs. Acta vet. scand. 1994, 35, 155-163.–Field trials were carried out testing a new genetically engineered vaccine against Progressive Atrophic Rhinitis. The vaccine contained a non-toxic recombinant derivative of the P. multocida toxin. The experimental vaccine was compared with a commercial vaccine in 4 farms and in 1 farm 2 different dose regimens were applied. A total of 825 sows were included. The primary efficacy variable was a comparison of post mortem evaluation of the degree of conchae atrophy in the 4585 pigs. The pigs were slaughtered at normal slaughter weight. The secondary efficacy variables were serological response and age at slaughter. In all farms the experimental vaccine provided significantly better protection of the progeny than the control vaccine. The serological response in sows was significantly higher in all farms than the response to the control vaccine. The serological response did not differ between farms.     

Studies of Mycoplasma mastitis in cattle. 5. Studies of udder pathogenicity of Mycoplasma and Acholeplasma strains of different origins

Isolated acholeplasma laidlawii strains exhibited highly differentiated behaviours regarding their udder pathogenicity. Twelve of 16 tested strains were pathogenic to udder. Symptoms of acute udder inflammation were caused by all ten A. laidlawii strains isolated from differentiated material of calf, but by only two of six strains isolated from differentiated material of cattle. Intracisternal instillation of both strains from milk and one strain each from udder skin or cervical mucus caused merely temporary disorders of secretion. Ultrasonic extracts of A. laidlawii strains, some of them additionally heated, were intracisternally applied, as well. Udder irritation was caused only by those acholeplasma strains which were udder-patha was assumed to be attributable to a toxin of the polysaccharide type. Pathogenicity to udder was recorded also from one M. alkalescens strain isolated from a nose swab taken of cattle as well as from two A. granularum strains isolated from calf lungs.