The use of biotin-labeled cDNA probes for the detection of infectious bursal disease viruses

A cDNA library was prepared from the double-stranded RNA genome of the infectious bursal disease virus (IBDV) strain ST-C. The cDNA molecules were annealed into the plasmid pUC9 and used to transform Escherichia coli strain JM107. A cDNA clone that contained IBDV-specific nucleotide sequences was selected and designated STC-1. Radiolabeled probes were prepared from STC-1 and hybridized to genome segment A of ST-C in a northern blot hybridization assay. The STC-1 cDNA was 448 base pairs in length, and its nucleotide sequence indicated that it is located near the VP-2/VP-4 junction in IBDV genome segment A. Biotin-labeled probes were prepared from STC-1 and used in a dot-blot hybridization assay to detect IBDV. Under relatively low stringency conditions of hybridization, the biotinylated probes detected four subtypes of IBDV serotype 1 and a serotype 2 IBDV isolate.     

Advances in methodology for diagnosis of allergic skin disease

Advantages of IDST for diagnosis of atopy and selection of antigens for hyposensitization include the following: 1. The test is widely accepted by clients. 2. The clinician can select individual test allergens based on the patient history and geographic location. 3. It has been the standard for diagnosing atopy in the dog for more than 40 years. Disadvantages of IDST include the following: 1. The test should be performed on a regular basis to maintain reliability. 2. Interpretation of test results is subjective. 3. The test is not standardized on the basis of the examiner, source of the allergen, or reproducibility. 4. There is occasional difficulty in performing the test (e.g., need for sedation). 5. Anaphylaxis is a potential risk. 6. A significant amount of office time is needed to perform the test. 7. Condition of the patient's skin (e.g., lichenification, hyperpigmentation, pyoderma) may preclude its use. 8. There is a possibility of failure to test for appropriate allergens. 9. There may be false-positive and false-negative reactions. 10. Other medications can interfere with the test (e.g., antihistamines, corticosteroids). Advantages of in vitro testing for diagnosis of atopy and selecting antigens for hyposensitization include the following.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mycobacterium paratuberculosis detection in bovine feces is improved by coupling agar culture enrichment to an IS900-specific polymerase chain reaction assay.

The feasibility of coupling an agar culture enrichment step with gene amplification (ACE-PCR) as a means to improve turnaround time and detect Mycobacterium paratuberculosis (Mpt) in the presence of contaminants was investigated. Fecal samples from 463 Pennsylvania dairy cows were cultured in duplicate sets. One replicate from each set was processed and interpreted according to standard culture (SC) protocol, whereas cultures from the second replicate were harvested at 6 weeks postinoculation; DNA extracts from the harvested material were evaluated by a polymerase chain reaction (PCR) test for the Mpt-specific IS900 gene. One hundred seventy-six of 463 culture sets were positive by either method. One hundred sixty-five of these (94%) were ACE-PCR positive, and 151 (86%) were positive by SC. Eleven SC-positive samples were ACE-PCR negative, and 9 ACE-PCR-positive samples were negative by SC; these discrepancies could be a consequence of a low organism burden (< or = 5 organisms/g) or slow growth rate of Mpt in cultures of these samples. One hundred thirty-nine of 463 culture sets (30%) were reported as inconclusive because of culture contamination according to SC protocol; 16 of these (11.5%) were ACE-PCR positive. Seventy-four ACE-PCR-positive sets (42% of all positives) were negative or inconclusive by SC at 6 weeks postinoculation. Agar culture enrichment prior to IS900 PCR testing significantly improves Mpt culture turnaround time and sensitivity.     

Microsatellite variation between an African and five European taurine breeds results in a geographical phylogenetic tree with a bison outgroup

Genetic variation is being used extensively for individual identification and linkage analysis, and may be useful for interpopulation studies. Previously, blood groups and biochemical variants in blood cell and serum proteins have been used to study (evolutionary) relationships in mammals. But genetic divergence and gene flow among closely related populations are difficult to measure with these classical markers because their mutation rate is so low that new mutations have not had sufficient time to appear and become fixed. So they have a small number of alleles and a relatively low level of heterozygosity. These markers are now replaced by DNA markers, mostly microsatellites. These microsatellite loci are useful genetic markers at which alleles differ in length due to differences in the number of short sequence motifs arranged adjacent to one another. They are abundantly distributed throughout the mammalian genome. They have a large number of alleles, a high level of heterozygosity and are inherited in true Mendelian fashion. These characteristics make them valuable for parentage control, linkage analysis, genome mapping and phylogenetic studies. In terrestrial vertebrates with limited mobility, genetic differentiation often increases with the distance between populations or corresponds to the extent of geographic and habitat barriers (R oy et al. 1994). Investigations of short tandem repeats yield a considerable volume of genetic data regarding the similarities and divergence times of different cattle populations. Microsatellite markers are suitable for the estimation of these parameters as they are not generally subject to direct selection and environmental influences. Computation of genetic distances based on data from several loci can be used to evaluate the taxonomic relationship between populations. The aim of this study was to estimate the relative genetic variability between Belgian cattle breeds and to reconstruct the evolutionary relationship among them, also using two small genetically isolated cattle-like populations.     

Feather folliculoma in a captive-bred barn owl (Tyto alba).

Proliferative cutaneous lesions are frequently encountered in examination of avian species. Tumors of the skin have been reported in many bird species, although comparatively less is known about the incidence of integumentary neoplasia in nondomesticated species than in production or companion species. An adult male, 9-yr-old, captive-bred barn owl (Tyto alba) was presented for examination of a proliferative skin mass of several months' duration on the left wing. An excisional biopsy was performed, and the owl recovered uneventfully. Light microscopic examination of tissue sections of the mass revealed a focal, unencapsulated, well-demarcated, multiloculated mass that consisted of variably sized cystic spaces lined by stratified squamous epithelium and containing concentric laminations of keratin and foci of feather differentiation. A histopathologic diagnosis of feather folliculoma was made. This neoplasm has not previously been described in owls. Its incidence and documentation are significant in that this neoplasm should be considered as a differential diagnosis of proliferative skin lesions in this raptorial species.     

Mesenchymal chondrosarcoma in a young German shepherd dog

An 18-month-old, entire male German shepherd dog was presented with signs indicative of a caudal abdominal space-occupying mass. A needle-core biopsy of this mass failed to establish a definitive diagnosis, but identified a prominent round-cell component. The dog's condition worsened and euthanasia was performed on humane grounds. Histopathology of the mass revealed a mesenchymal chondrosarcoma.     

Dynamics in the membrane organization of the mammalian sperm cell and functionality in fertilization

The capacitation process of sperm cells involves complex changes in the composition and orientation of molecules at the surface of the sperm cell. Here we focus on the lipid architecture in the sperm plasma membrane and demonstrate that the sperm plasma membrane is not static but is an extremely dynamic structure. Advanced fluoroscopic techniques enabled continuous monitoring of lipid organization in living cells and extremely rapid lipid movements were observed. The orientation of lipids in the sperm plasma membrane changed under capacitative treatments, was found to be sensitive for temperature and also changed upon binding of sperm cells to the zona pellucida. The changes in membrane properties coincided with an activation of protein kinases resulting in tyrosine phosphorylation of specific plasma membrane proteins. The detected membrane changes relate to intrinsic membrane properties such as fluidity, permeability, adhesiveness and fusibility. We think that these results may provide a physiological basis for new assays, able to discriminate between functional and non-physiological sperm cells.     

A new isolate of the nematophagous fungus Duddingtonia flagrans a biological control agent against free-living larvae of horse strongyles

An experiment was carried out in 1997 to test the efficacy of an isolate of the microfungus Duddingtonia flagrans against free-living stages of horse strongyles under conditions in the field and to assess the eventual effect of the fungus on the normal degradation of faeces. Faecal pats were made from faeces of a naturally strongyle infected horse, which had been fed fungal material at a dose level of 106 fungal unit/kg bwt. Control pats without fungi were made from faeces collected from the same animal just before being fed fungi. Faecal cultures set up for both groups of faeces to monitor the activity of the fungus under laboratory conditions showed that the fungus significantly reduced the number of infective third-stage larvae (L3) by an average of 98.4%. Five faecal pats from each batch of faeces were deposited on pasture plots at 3 times during spring-summer. The herbage around each pat was sampled fortnightly to recover L3 transmitted from faeces. The results showed that the herbage infectivity around fungus-treated pats was reduced by 85.8-99.4%. The remaining faecal material at the end of each sampling period was collected, and the surviving L3 were extracted. Significantly fewer larvae were recovered from the fungus-treated pats. Analysis of wet and dry weight of the collected pats, as well as their organic matter content, were performed to compare the degradation of faeces of both groups. The results indicated that the presence of the fungus did not alter the degradation of the faeces.     

Extensive umbilical herniation of the large colon in a foal

A 5‐month‐old Warmblood cross colt was presented with focal swelling of the ventral abdomen extending from the umbilicus to the scrotum in the absence of colic signs. Palpation and ultrasound examination revealed the presence of incarcerated large intestine within the subcutaneous space adjacent to the caudal ventral abdomen and prepuce. Surgery was performed and revealed that the umbilical hernia sac had ruptured, and confirmed that the left dorsal and ventral colon were present in the subcutaneous space. The mild degree of vascular compromise of the large colon did not necessitate resection and so it was replaced within the abdomen. The abdominal wall defect was closed and the subcutaneous dead space was reduced by using a walking suture pattern. Herniation of the large colon through the umbilicus with dissection through the subcutaneous tissues of the ventral abdominal wall and prepuce has not been previously reported in foals. Ultrasonography permits differentiation of herniated small intestine from large intestine.