The use of genetic modification technologies in the discovery of genes affecting production traits and disease resistance in animals

Genetic modification technologies, developed initially in laboratory strains of selected bacteria and viruses, are essential tools for understanding the genomes of livestock. These tools allow researchers to: isolate, sequence and characterise any livestock gene; locate genes on chromosomes; follow the inheritance of any gene and/or chromosomal region in any pedigree; detect phenotypic variation due to, or associated with, variation in the DNA sequence of a gene and identify the genetic alteration causing this. Most of the many thousands of genes identified in livestock vary between individuals. Finding the best type of the key genes affecting animal productivity is an exciting and a daunting task. It is only possible with the use of laboratory-based genetic modification techniques. This review will briefly describe the technologies now in use and, using local examples, show how molecular geneticists are using these to help identify genetic alterations and breed healthier or more productive animals. As with any new technology, a new language evolves to describe new products and processes. The new language makes communication easier between participants in the field but more difficult for others to understand the technology. A glossary of terms has therefore been added to this review to help readers less familiar with molecular genetics.     

First cases of animal diseases published since 2000. 3. Cattle

In this third article of a series of papers listing first case reports of animal diseases published since 2000, the following seven cases of cattle diseases are discussed: AL amyloidosis. Canola oil intoxication. Disseminated intracytoplasmic neuronal vacuolation. Encephalomyelitis associated with Akabane virus infection in adult cows. Lower limb deformity: "mirror image duplication of the plantar/palmar half of the distal portion of the digit". Lupinus argenteus intoxication. Novel Propionibacterium infection. After a short introduction, the bibliographical data, the abstract of the author(s), and some additional information derived from the article are given. The article will be regularly updated adding overlooked as well as new first reports.     

Mandibular pyogranulomatous osteomyelitis in a Sannen goat

Mandibular pyogranulomatous osteomyelitis was diagnosed in a female Sannen goat. The doe presented for difficulty prehending and chewing food. The left mandible was swollen and firm on palpation. Radiographs revealed changes consistent with osteomyelitis of the affected mandible. Arcanobacterium pyogenes was isolated from aspirates of swollen mandible. Despite antimicrobial therapy, the goat died. Histopathological findings were consistent with pyogranulomatous disease of the affected mandible. The histopathological findings were similar to those reported for actinomycosis, caused by Actinomyces bovis. Mandibular osteomyelitis is a common condition in cattle and very rare in goat.     

Influence of platelet count,acetylsalicylic acid,von Willebrand's disease,coagulopathies, and haematocrit on results obtained using a platelet function analyser in dogs

The platelet function analyser PFA-100 aspirates blood in vitro from a sample reservoir in disposable test cartridges through a microscopic aperture cut into a biologically active membrane at the end of a capillary. In different cartridges the membrane is coated with collagen and adenosine diphosphate (ADP) or collagen and epinephrine (adrenaline) inducing a platelet plug and closure of the aperture. The closure time and total volume of blood flow through the capillary until closure of its aperture were measured. The correlation between platelet count in samples of thrombocytopenic dogs and results of the collagen/ADP cartridge (closure time: r(S)=-0.579; total volume: r(S)=-0.549) was closer than between platelet count and capillary bleeding time. No significant correlation was observed between platelet count and the results obtained with the collagen/epinephrine cartridge. In addition, a higher sensitivity was obtained for the collagen/ADP cartridge. Injection of acetylsalicylic acid into healthy dogs significantly increased closure time and total volume of both types of cartridges (P<0.01). Two dogs with von Willebrand's disease had abnormal values. In contrast, coagulopathies did not significantly influence the results of the platelet function analyser (P>0.05). Despite adequate sensitivity of measurements using the collagen/ADP cartridge to assess quantitative and qualitative platelet disorders in dogs, the influence of haematocrit (P<0.0001) will limit the clinical application of the analyser.     

Simultaneous one-tube quantification of host and pathogen DNA with real-time polymerase chain reaction

ABSTRACT Phaeocryptopus gaeumannii is a widespread foliar parasite of Douglas-fir. Although normally innocuous, the fungus also causes the defoliating disease Swiss needle cast in heavily infected needles. The extent of P. gaeumannii colonization in Douglas-fir foliage was estimated with real-time quantitative polymerase chain reaction (PCR) using TaqMan chemistry. In order to derive a normalized expression of colonization, both pathogen and host DNA were simultaneously amplified but individually detected by species-specific primers and TaqMan probes labeled with different fluorescent dyes. Detection of host DNA additionally provided an endogenous reference that served as both an internal positive control and adjusted for variation introduced by sample-to-sample differences in DNA extraction and PCR efficiencies. The genes employed for designing the TaqMan probes and primers were beta-tubulin for the pathogen and a LEAFY/FLORICAULA-like gene involved in floral development for the tree host. Both probe/primer sets exhibited high precision and reproducibility over a linear range of 4 orders of magnitude. This eliminated the need to analyze samples in multiple dilutions when comparing lightly with heavily infected needles. Quantification of the fungus within needles was successful as early as 1 month after initial infection. Real-time PCR is the only method currently available to quantify P. gaeumannii colonization early in the first year of the colonization process.     

Comparison of ITS profiling,REP- and ERIC-PCR of Salmonella Enteritidis isolates from Poland

Thirty-one Salmonella Enteritidis strains isolated from chickens, broilers and hens were analysed by genotypic typing including REP-PCR. ERIC-PCR and ITS profiling (PCR-ribotyping). Analysis of DNA banding patterns generated by REP-PCR revealed the presence of 22 different genotypes, which were grouped by dendrogram analysis into three distinct lineages (maximum similarity approx. 50%). Each isolate of S. Enteritidis analysed by ERIC-PCR generated an individual DNA pattern. Again, these isolates could be divided into three distinct genomic groups (maximum similarity approx. 60%) by their ERIC-PCR fingerprints. REP- and ERIC-PCR were found to be more discriminatory for typing of S. Enteritidis than ITS profiling. Amplification of the 16S-23S rDNA spacer region gave nine different profiles of DNA, subdivided into two closely related groups by dendrogram analysis. In summary, data obtained by genotyping methods for S. Enteritidis isolates from regions located in the south-west and the central parts of Poland revealed an enormous heterogeneity among analysed samples, and proved that REP- and ERIC-PCR are highly discriminatory techniques, which can be used, in addition to conventional methods, in epidemiological studies of S. Enteritidis infections.