Differential reactivity of bovine lymphocytes to species of Brucella

The reactivity of bovine lymphocytes to 4 species of Brucella was tested in thymidine-uptake assays, using long-term cultured lymphocytes and freshly obtained blood mononuclear cells. Lymphocytes were taken from cows that had been challenge exposed with a virulent strain of B abortus at midgestation. The cows were classified retrospectively as being naturally resistant or susceptible to brucellosis. Lymphocytes taken from these cows had 3 patterns of reactivity with species of Brucella: pattern 1 was defined by reactivity with 4 species (B abortus, B canis, B suis, and B melitensis); pattern 2 was defined by reactivity with all these species, except B melitensis; pattern 3 was defined by reactivity with B abortus and B canis, but not with B suis or B melitensis. There was a statistically significant correlation between susceptibility to brucellosis and expression of lymphocyte cross-reactivity with B suis (P less than 0.01) and with B melitensis (P less than 0.001).     

Survival of smooth, rough and transposon mutant strains of Brucella abortus in bovine mammary macrophages

Transposon mutants offer a unique way to evaluate the role of lipopolysaccharide (LPS) by producing a theoretical single-gene difference between the original strain and the transposon mutant strain. Comparative survival of Brucella abortus smooth strain 2308, rough RB51, smooth strain 19, and two transposon mutant strains (rough strain 2308::Tn5 Lac Z [m106] and rough strain 19::Tn5 Lac Z [m3], was tested in restrictive bovine mammary macrophages that were able to effectively reduce the percentage of intracellular bacterial survival and permissive bovine mammary macrophages that were unable to control the intracellular replication of B. abortus. The theoretical single-gene difference between strain 19 and strain 19::Tn5 lac Z [m3] and between smooth virulent strain 2308 and rough transposon mutant 2308::Tn5 lacZ [m106] is likely related to differences in LPS content or structure. Significant (P less than 0.05) reduction in the survival of rough strain 19::Tn5 Lac Z [m3] with no significant reduction in the rough transposon mutant strain 2308::Tn5 lacZ [m106] indicated that at least one factor other than LPS contributes to the intracellular survival of B. abortus in bovine macrophages.     

Myocardial and pancreatic lesions induced by T-2 toxin, a trichothecene mycotoxin, in swine

Myocardial and pancreatic lesions induced by sublethal doses of T-2 toxin in swine were characterized by light and electron microscopy. Toxin was given intravenously to six 17- to 18-week-old pigs. Pigs were killed 24 or 48 hours after treatment. Grossly, subendocardial hemorrhages, multifocal pinpoint white foci in myocardium, and pancreatic edema occurred in one treated pig. Histologic changes in myocardium of treated pigs consisted of multifocal edema, mononuclear cell infiltration, myofiber hyalinization, vacuolation, and contraction bands with nuclear pyknosis. Ultrastructurally, there were areas of edema, myofibrillar disorganization, dilation of sarcoplasmic reticulum, and formation of hypercontraction bands. Myocardial mineralization was seen in the pig with gross lesions. Pancreatic changes in treated pigs consisted of multifocal acinar degeneration and necrosis. Ultrastructural changes included irregular dilation of rough endoplasmic reticulum and abnormal zymogen granules. Thus, in addition to radiomimetic lesions of the gastrointestinal tract and lymphoid organs, heart and pancreas are target organs of T-2 toxin in swine.     

Effect of crop load on fruiting and leaf photosynthesis of 'Braeburn'/M.26 apple trees

Four-year-old apple (Malus x domestica Borkh.) trees cv. 'Braeburn' on M.26 rootstock were thinned at full bloom to establish six crop loads ranging from a heavy crop to a deflowered treatment. At harvest, mean yield per tree varied from 0 to 38 kg and mean fruit weight ranged from 225 g in the heaviest cropping treatment to 385 g in the lightest cropping treatment. Light cropping resulted in a significant advance in fruit maturity as indicated by background color, starch/iodine score and soluble solids. There were small differences in leaf photosynthetic rate among the treatments when shoot growth was active. However, in early January, coincident with cessation of shoot growth and maximum rate of accumulation of fruit weight, leaf assimilation rate was reduced by as much as 65% on the deflowered trees compared to the trees carrying the heaviest crop. Leaf assimilation rate showed a curvilinear response to crop load at this time, with little increase in leaf assimilation when crop load exceeded 12 fruit m(-2) leaf area.     

Acquired cervical spinal arachnoid diverticulum in a cat

A one‐year‐old, female entire, domestic, shorthair cat presented with acute onset non‐ambulatory tetraparesis. Magnetic resonance imaging was consistent with a C3‐C4 acute non‐compressive nucleus pulposus extrusion and the cat was treated conservatively. The cat was able to walk after 10 days and was normal 2 months after presentation. The cat was referred five and a half years later for investigation of an insidious onset 3‐month history of ataxia and tetraparesis. Magnetic resonance imaging of the cervical spine was repeated, demonstrating a spinal arachnoid diverticulum at C3 causing marked focal compression of the spinal cord. This was treated surgically with hemilaminectomy and durectomy. The cat improved uneventfully and was discharged 12 days later.     

Arctic charr in Britain and Ireland – 15 species or one?

Abstract –  From both a modern and a historical perspective there is little doubt that the Arctic charr, Salvelinus alpinus , in Britain and Ireland (as well as elsewhere) is a 'difficult' species. Historically 15 separate species have been recognised from populations in Britain and Ireland and there have been recent attempts to reassert these specific names. Here we review the evidence for the status of these 'species'. We conclude that the evidence for these 15 being afforded full species status is poor. However, both historical and contemporary data show that Salvelinus alpinus (Linnaeus 1758) in Britain and Ireland exhibits levels of variability in form that is much greater than in other species. We argue that a comprehensive genotypic and phenotypic survey of charr populations in Britain and Ireland is required to determine the full extent of variability and the status of populations with a view of providing suitable protection.     

Identification of Mycobacterium spp. isolated from snakehead, Channa striata (Fowler), and Siamese fighting fish, Betta splendens (Regan), using polymerase chain reaction–reverse cross blot hybridization (PCR–RCBH)

A variety of methods have been used to identify Mycobacterium spp. isolated from snakehead and Siamese fighting fish, including biochemistry, mycolic acid profiles and antibody-based methods. However, these methods are unable to differentiate between different species of Mycobacterium . Polymerase chain reaction (PCR) followed by reverse cross blot hybridization (RCBH) was adapted in this study to speciate aquatic mycobacteria. The method was highly specific for Mycobacterium spp. and identified the bacteria to species level with a detection limit of 100 fg DNA, equivalent to 20 mycobacteria. Twenty-nine isolates previously collected and cultured from Siamese fighting fish (10 isolates) and snakehead (19 isolates) during outbreaks of mycobacteriosis were analysed using PCR–RCBH. Six of the Siamese fighting fish isolates and nine of the snakehead isolates were identified as Mycobacterium fortuitum , while the remainder were classified as M. marinum . Notably, two isolates recovered from snakehead and Siamese fighting fish, previously identified as M. poriferae and M. piscicida , respectively, were confirmed to be M. fortuitum .