Identification and characterization of complete RTX operons in Moraxella bovoculi and Moraxella ovis

To determine if Moraxella bovoculi (M. bovoculi), a recently characterized coccoid Moraxella that was isolated from the eyes of calves affected with infectious bovine keratoconjunctivitis (IBK), and Moraxella ovis (M. ovis), originally isolated from sheep with conjunctivitis, possessed genes encoding RTX proteins, genomic DNA was amplified with oligonucleotide primers targeting RTX operon genes of Moraxella bovis (M. bovis). Complete classical RTX operons composed of RTXCABD genes closely linked to a putative secretion accessory protein encoding gene (tolC) were identified in M. bovoculi and M. ovis and were designated mbvCABDtolC and movCABDtolC, respectively. These genes were closely related to M. bovis mbxCABDtolC. Polyclonal rabbit antiserum against the carboxy terminus of M. bovoculi MbvA neutralized hemolytic activity of both M. bovoculi and M. ovis; this antiserum did not neutralize the hemolytic activity of M. bovis. M. bovoculi and M. ovis possess genes that encode proteins related to pathogenic factors of M. bovis.     

Habitat overlap of juvenile and adult lake trout of Great Bear Lake: Evidence for lack of a predation gradient?

A range of organisms, from plankton to fish, commonly shift their habitat distributions horizontally or vertically due to predation risk. Juvenile lake trout, Salvelinus namaycush, are generally viewed as occupying deep areas of lakes to decrease predation pressure from adults. In contrast, we found that juvenile lake trout from Great Bear Lake, NT, Canada, occupied a variety of habitats and from shallow to deep depths (0–150 m), overlapping with adult lake trout. No evidence occurred for a length depth‐based segregation (e.g., ontogenetic shift). Genetic variation was also similar among juveniles in the different depth zones. However, isotopic niches and C:N ratios among juveniles showed some variability in niche widths and positions for individuals caught from the 51–150 m zone compared to juvenile individuals caught from 0–20 m and 21–50 m zones. The uniformly distributed adult lake trout in Great Bear Lake may evenly distribute predation pressure (including cannibalism) across shallow‐ and deep‐water habitats more than in other lakes. As a result, juveniles may respond to differences in foraging opportunities rather than predation risks. Juvenile lake trout did not appear to conform to the general pattern of juveniles seeking a deep‐water refuge to reduce predation risks. In contrast, juvenile lake trout of Great Bear Lake displayed broad resource use across all depths and habitats.     

The basis of host recognition in Fusarium oxysporum f. sp. lycopersici

Filtrates from shake-cultures of Fusarium oxysporum f. sp. lycopersici race 1, concentrated to 20% of the original volume, caused cell death in tomato leaf protoplasts from near-isogenic lines corresponding to the compatible cultivar/race reactions of whole plants. Maximum activity was found in late log phase cultures on Czapek-Dox supplemented with 2% casamino acids. Selective toxicity was associated only with the protein fraction of the culture filtrate. LD₅₀ values for susceptible Ace and Moneycross to F. oxysporum f. sp. lycopersici race 1 culture filtrates were 1·92 and 0·36 μg protein ml⁻¹. Corresponding values for cvs Royal Ace and MM161, each containing the I-gene conferring resistance to race 1, were >350. Culture filtrates from F. oxysporum f. sp. lycopersici race 2 gave LD₅₀ values of 2·34 and 2·08 μg protein ml⁻¹ on cvs Ace and Royal Ace, both susceptible to race 2. The LD⁵⁰ of cv. Ace to a non-pathogenic isolate of F. xysporum f. sp. lycopersici was > 350. Culture filtrates from non-host formae of F. oxysporum were 9–149-fold less toxic on cv. Ace. Protoplasts from Pisum sativum, Lactuca sativa, Zea mays, Gossypium barbadense and Solanum melongena, all non-hosts of F. oxysporum f. sp. lycopersici, were 6–175 times less sensitive to F. oxysporum f. sp. lycopersici filtrates than susceptible tomato. The putative toxins lycomarasmin and fusaric acid showed no differential toxicity to I⁺ and I⁻ tomato protoplasts. The results are discussed in the wider context of host-pathogen interaction in which specificity is considered as the recognition of susceptibility by a proteinaceous toxic metabolite of the pathogen. This hypothesis is further extended to include the specificity of F. oxysporum formae and races.     

Gastrointestinal ultrasonography in normal adult ponies

The objective of this study was to determine the characteristics based on ultrasonographic examination of the stomach, duodenum, jejunum, cecum, and peritoneal fluid in normal adult ponies. Abdominal ultrasonographic examination was performed in nine unsedated standing ponies. The duodenum was examined at three sites and the jejunum in 12 regions. Wall thickness, contractility, distention, and luminal contents were recorded. Stomach wall thickness and location, cecal wall thickness, and peritoneal fluid location and character were recorded. Statistical analysis was performed. Wall thicknesses (in cm) were 0.431 +/- 0.069 for the stomach, 0.188 +/- 0.033 for the duodenum (at all sites), 0.195 +/- 0.031 for the jejunum (at all regions), and 0.179 +/- 0.031 for the cecum. Duodenal contractions per minute were 3.78 +/- 1.10. The stomach spanned 5.14 +/- 0.9 intercostal spaces, with the 8th intercostal space being the most cranial and the 15th intercostal space being the most caudal space through which the stomach was identified. It was possible to identify the jejunum in all ponies dorsal to the left dorsal colon and from the ventral abdominal wall. Peritoneal fluid was identified in six ponies. Peritoneal fluid was usually seen transiently and most commonly in the ventral aspect of the abdominal cavity or around the duodenum. Overall, the ponie's abdominal ultrasonographic examinations revealed wall thicknesses that were less than the published normal ranges for horses. It appears that ponies may have increased duodenal contractility than horses and that the conformation of ponies may change the locations for imaging the stomach.     

The variation in hectolitre weight of wheat grain fed with or without enzyme supplementation influences nutrient digestibility and subsequently affects performance in pigs

A 2 × 2 factorial experiment was conducted to investigate the effect of feeding a wheat‐based diet of two different hectolitre weights (66 vs. 74 kg/hl), achieved through different agronomical conditions, with or without the supplementation of a β‐glucanase and β‐xylanase enzyme mix on young pigs. The parameter categories which were assessed included growth performance, coefficient of apparent total tract digestibility (CATTD), faecal consistency, faecal microbial populations and faecal volatile fatty acid (VFA) concentrations. Sixty‐four pigs (11.6 kg SD 0.97) were assigned to one of four dietary treatments: (T1) low hectolitre weight wheat diet, (T2) low hectolitre weight wheat diet containing 0.1 g/kg β‐glucanase and β‐xylanase enzyme supplement, (T3) high hectolitre weight wheat diet and (T4) high hectolitre weight wheat diet containing 0.1 g/kg β‐glucanase and β‐xylanase enzyme supplement. The inclusion of wheat was 500 g/kg in the diet. The low hectolitre weight grain had a higher level of zearalenone, aflatoxin and ochratoxin contamination compared to the high hectolitre weight grain. The high hectolitre weight wheat had a higher gross energy (GE), crude protein (CP) and lysine contents compared to the low hectolitre weight wheat. Pigs offered the low hectolitre weight diet had a lower average daily gain (ADG) (p < 0.001), a lower gain to feed (G:F) ratio (p < 0.001) and a higher faecal score (more diarrhoea) (p < 0.001) compared to pigs offered the high hectolitre weight. The low hectolitre weight diet had a reduced CATTD (p < 0.05) of nitrogen (N) and gross energy (GE) compared with pigs offered the high hectolitre weight diet. In conclusion, the higher level of mycotoxins and lower content of GE, CP and lysine in the low‐quality wheat reduced ADG and the CATTD of nutrients in pigs offered this diet. The inclusion of a β‐glucanase and β‐xylanase enzyme mix had no effect on growth performance or nutrient digestibility.     

Physical characteristics of gastrointestinal content of llama (Lama glama)

Changes in digesta dry matter (DM) and mean digesta particle size (MPS) along the gastrointestinal tract are well known in ruminants, but not in camelids. We collected digesta from the dorsal (d) and ventral (v) first forestomach compartment (C1), the second forestomach compartment (C2), three proximal segments and the subsequent glandular part of the third compartment (C3A‐D), the caecum and the faeces twelve llamas (Lama glama). DM analysis indicates the presence of digesta stratification in the C1, the presence of fluid in the C2 to facilitate the sorting function of this compartment, the fluid‐absorbing function of the proximal parts of the C3, the secretion of enzymes and digestive acids in the C3D, and the water‐resorbing function of the lower intestinal tract. These findings illustrate the functional resemblance between the gastrointestinal tract of camelids and cattle‐like ruminants (C1 equivalent to the rumen with stratified contents, C2 to the reticulum, C3A/B/C to the omasum and C3D to the abomasum). MPS analysis revealed a progressive reduction in MPS from the C1 to the distal C3. This gradual transition is different from the clear‐cut threshold in ruminants between the reticulum and the omasum and had so far only been described in dromedaries (Camelus dromedarius). These findings indicate that regardless of the convergent property of rumination and resemblance of general mechanisms involved in contents stratification and particle sorting, differences between ruminants and camelids exist that could be interpreted as a more efficient functionality of the ruminant forestomach.     

Use of machine-learning algorithms to aid in the early detection of leptospirosis in dogs

Leptospirosis is a life-threatening, zoonotic disease with various clinical presentations, including renal injury, hepatic injury, pancreatitis, and pulmonary hemorrhage. With prompt recognition of the disease and treatment, 90% of infected dogs have a positive outcome. Therefore, rapid, early diagnosis of leptospirosis is crucial. Testing for Leptospira-specific serum antibodies using the microscopic agglutination test (MAT) lacks sensitivity early in the disease process, and diagnosis can take >2 wk because of the need to demonstrate a rise in titer. We applied machine-learning algorithms to clinical variables from the first day of hospitalization to create machine-learning prediction models (MLMs). The models incorporated patient signalment, clinicopathologic data (CBC, serum chemistry profile, and urinalysis = blood work [BW] model), with or without a MAT titer obtained at patient intake (=BW + MAT model). The models were trained with data from 91 dogs with confirmed leptospirosis and 322 dogs without leptospirosis. Once trained, the models were tested with a cohort of dogs not included in the model training (9 leptospirosis-positive and 44 leptospirosis-negative dogs), and performance was assessed. Both models predicted leptospirosis in the test set with 100% sensitivity (95% CI: 70.1–100%). Specificity was 90.9% (95% CI: 78.8–96.4%) and 93.2% (95% CI: 81.8–97.7%) for the BW and BW + MAT models, respectively. Our MLMs outperformed traditional acute serologic screening and can provide accurate early screening for the probable diagnosis of leptospirosis in dogs.