Prevalence of Leptospira interrogans serovar hardjo antibodies in milk in Belgian dairy herds

Pooled milk samples were collected from 2000 Belgian dairy herds in the autumn of 1989. Antibodies against Leptospira interrogans serovar hardjo were detected in 9.2% of the herds, with the incidence being higher in the southern part of the country.     

Immunohistological study of the immune system cells in paraffin-embedded tissues of conventional pigs

The distribution of different cells of the immune system has been studied in formalin-fixed paraffin-embedded tissues from conventionally reared healthy pigs, using immunohistological techniques. The samples collected were: lungs, tonsils, lymph nodes (mediastinal, mesenteric, inguinal and submandibular), pancreas, spleen, liver, kidney, adrenal gland, ileum and stomach. A total of six primary antibodies anti-CD3, anti-CD79alpha, Mac 387, anti-lysozyme, anti-CD45RA (3C3/9) and anti-SLA-II-DQ (BL2H5) were used with a standard avidin-biotin peroxidase (ABC) method. Anti-CD3 and anti-CD79alpha mAb-reacted, respectively with cells located in T cell areas and B cell areas. Mac 387 recognised circulating polymorphonuclear leukocytes, while anti-lysozyme-stained resident macrophages in all tissues. 3C3/9 and BL2H5, were assessed in formalin-fixed paraffin-embedded tissues for the first time. 3C3/9 identified B lymphocytes, in primary follicles and mantle zones, a subpopulation of T cells, especially located in the marginal zone of the spleen and a variable number of immunoblasts, in the germinal centres. BL2H5 reacted with B cells in the mantle zones of the follicles of lymphoid tissues, with dendritic and interdigitating cells in all studied lymphoid tissues and with a variable number of resting and activated T cells in the periarteriolar lymphoid sheath (PALs), marginal zone and red pulp of the spleen. Furthermore, it stained Kupffer and perivascular macrophages in the liver. This study represents a detailed histological study of the distribution of the most important subpopulations of immune system cells in conventional, healthy pigs. In our view, these tools should be useful for future comparative studies in disease conditions.     

Risk factors for brucellosis seroprevalence of sheep and goat flocks in Spain

Risk factors for ovine and caprine brucellosis in the Ávila region (center of Spain) were evaluated using data from a cross-sectional study of the most important diseases of small ruminants in this Spanish region between 1996 and 1997. Questionnaire data from 56 herds (35 ovine and 21 caprine) were used. Sixteen (29%) flocks (3 caprine and 13 ovine) were brucellosis-seropositive. Overall, 0.7% of sheep and 0.1% of goats were seropositive. Eleven risk factors were studied at the group level by logistic regression using flock brucellosis-status as outcome, and by linear regression using percentage of brucellosis-seropositivity as outcome. Both final models contained the same variables: contact with sheep and grazing in communal pastures as risk factors, and frequency of disinfecting practices as a protective factor.     

Serodiagnosis of haemonchosis with a somatic antigen (Hc26) in several breeds of sheep.

Sera from 53 sheep belonging to Castellano, Churro, Manchego, and Merino breeds were analyzed to test the diagnostic value of a 26-kD antigen from adult Haemonchus contortus at prepatency and early and late patency of experimental haemonchosis. Animals that received zero, 1, or 2 infections with the parasite were tested. In addition, sera from 20 experimentally infected and 10 noninfected Texel sheep were used to test the antigen. Sera from 37 infected animals at prepatency as well as at patency in primary and secondary infection were found positive with the 26-kD antigen. However, sera from 10 animals with the lowest worm burdens (second infection) did not recognize the antigen during early patency (day 28 postinfection). IgG1 was the only isotype implicated in antigen recognition because IgG2, IgA, and IgM, in the same sera, showed no reactivity with the peptide. Antigen specificity was confirmed because hyperimmune sera against infective larvae and adult stages of the most common gastrointestinal nematodes found in natural infections in sheep (Trichostrongylus colubriformis and Teladorsagia circumcincta) did not recognize this peptide. The antigen was recognized only by anti-adult H. contortus hyperimmune sera and appeared to be absent in the L3 parasite stage. In addition, the partial N-terminal amino acid sequence of the diagnostic peptide is reported.     

A novel source of resistance to the two-spotted spider mite in Lycopersicon pimpinellifolium (Jusl.) Mill.: its genetics as affected by interplot interference

We have previously found an accession of Lycopersicon pimpinellifolium (Jusl.) Mill. (`TO-937') that appeared to resist attack by the two-spotted spider mite (Tetranychus urticae Koch). L. pimpinellifolium is a very close relative of the cultivated tomato (Lycopersicon esculentum Mill.) and thereby a potential source of desirable traits that could be introgressed to the crop species. The objective of this study was to investigate the genetics of the resistance present in `TO-937'. Resistance to infestation by the spider mite was quantified in 24-plant plots of L. pimpinellifolium accessions `TO-937' and `PE-10', L. pennellii accession `PE-45', L. esculentum cultivars `Moneymaker', `Roma' and `Kalohi' (reported to be partially resistant: Stoner & Stringfellow, 1967), and the interspecific F₁ cross, L. esculentum `Moneymaker' × L. pimpinellifolium `TO-937'. Only `TO-937', the F<sub>1</sub>, and`PE-45' were found to be resistant. Resistance of `TO-937' was complete when evaluated in two small greenhouses completely planted with `TO-937' so as to simulate the genotypic homogeneity usual in commercial crops. Generations (P₁, P₂, F₁, F₂, BC₁P₁, and BC₁P₂) of a P₁ (susceptible) × P₂ (resistant) cross (`Moneymaker' × `TO-937') were studied for resistance in a single-plant per plot design. Resistance of `TO-937' was inherited with complete dominance and appeared to be controlled by either two or four genes according to whether segregation in the F₂ or the BC₁P₁, respectively, were considered. However, calculation of the number of genes involved in the resistance was complicated by negative interplot interference due to the high frequency of resistant genotypes within most of the generations. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of cropping systems under no‐till agriculture on arbuscular mycorrhizal fungi in Argentinean Pampas

Here, we compare arbuscular mycorrhizal fungi (AMF) communities and fatty acids in soils under different no‐till (NT) agricultural managements over two seasons in two consecutive years. Two NT practices with different agricultural managements were compared: crop rotation (CR) and soya bean monoculture (MC). Soils of natural grasslands (NGs) were used as a reference. Treatments were tested along a regional gradient (four geographical locations) across a 400‐km transect of the Argentinean Pampas. We identified 46 morphospecies. Several morphospecies occurred abundantly at all soils; others appeared to be restricted to specific situations. At the regional scale, CR maintained the same richness levels of AMF spores, whereas MC showed less richness, when compared with the NG. Although AMF spore density was clearly affected by cropping practices in the four locations, we could observe some changes in AMF species richness, and similar diversity under agricultural and natural soils. Fatty acid concentrations (whole‐cell, phospholipid and neutral lipid fatty acids) revealed differences between soil managements and showed similar patterns of variation in all locations. Spore density positively correlated with all soil lipids fractions. The results suggest that AMF spore communities and fatty acids in soils are suitable indicators of soil management involving different levels of crop rotation. Spore richness measured at a regional scale proved to be sensitive to different NT agricultural managements. Moreover, certain morphospecies could be good bioindicators for NT practices based on cropping systems on the Argentinean Pampas.     

IMAGING DIAGNOSIS—ULTRASONOGRAPHIC APPEARANCE OF SMALL BOWEL METASTASIS FROM CANINE MAMMARY CARCINOMA

A 10‐year‐old entire female Beagle dog was evaluated for an acute history of lethargy, anorexia, and diarrhea. Mammary tumors were detected during physical examination. Ultrasonographic scanning revealed the presence of a unique pattern of multiple, well‐defined and well‐marginated hypoechoic nodules in the muscularis layer of the jejunum. These nodules were not associated with changes in the rest of the normal intestinal layering and were not causing signs of intestinal obstruction. Mammary carcinoma metastases to the intestinal muscularis layer were diagnosed based on histopathological examination.     

Processive movement of MreB-associated cell wall biosynthetic complexes in bacteria

The peptidoglycan cell wall and the actin-like MreB cytoskeleton are major determinants of cell shape in rod-shaped bacteria. The prevailing model postulates that helical, membrane-associated MreB filaments organize elongation-specific peptidoglycan-synthesizing complexes along sidewalls. We used total internal reflection fluorescence microscopy to visualize the dynamic relation between MreB isoforms and cell wall synthesis in live Bacillus subtilis cells. During exponential growth, MreB proteins did not form helical structures. Instead, together with other morphogenetic factors, they assembled into discrete patches that moved processively along peripheral tracks perpendicular to the cell axis. Patch motility was largely powered by cell wall synthesis, and MreB polymers restricted diffusion of patch components in the membrane and oriented patch motion.