Factors associated with development of Canine Infectious Respiratory Disease Complex (CIRDC) in dogs in 5 Canadian small animal clinics

This study investigated the association between presence of respiratory pathogens and development of Canine Infectious Respiratory Disease Complex (CIRDC) in dogs in 5 Canadian small animal clinics. In total, 86 dogs were tested using a commercial PCR respiratory panel; 64 dogs were considered as cases and 22 were control dogs matched by veterinary clinic. No control animals (0/22) were positive for canine parainfluenza virus (CPIV), whereas 27/64 (42%) CIRDC cases were positive. Furthermore, 81% of case dogs tested positive for Mycoplasma cynos, compared with 73% of control dogs. Canine respiratory corona virus (CRCoV) was detected in no control dogs compared with 9.4% of clinical dogs. No animals were positive for any influenza virus type A present in the diagnostic panel. Presence of CPIV was associated (P < 0.01) with the occurrence of CIRDC after adjustment for demographic factors and presence of CRCoV (P = 0.09).     

Physiological alterations in pepper during wilt induced by Phytophthora capsici and soil water deficit

Capsicum annuum cv. Morrón inoculated at the collar with Phytophthora capsici developed cortical stem necrosis and severe wilting soon after infection. Water potential, specific conductivity, ethylene evolution, CO₂ and water vapour exchange rates and chlorophyll content were monitored during symptom development. Well watered and non-inoculated water-stressed plants were used as controls. Necrosis developed upwards from the collar 4 days after inoculation coupled with a 80% reduction in hydraulic conductivity. Leaf water potential progressively decreased from -0.17 to -2.41 MPa in 2 weeks. The rate of ethylene evolution was significantly higher in infected than in non-inoculated stressed plants for similar water potentials and originated in the necrotic segment of disease stem tissue. Net photosynthesis and leaf conductance markedly decreased (74%) 4 days after infection, coupled to a burst in dark respiration (1.5 times) but were not associated with water stress alone. This suggests that the pathogen reduced photosynthesis initially through stomatal closure which was not directly mediated by water stress. The possible implication of ethylene in impaired stem conductivity and altered gas exchange of infected plants is discussed.     

Survival of Didymella rabiei in chickpea straw debris in Spain

Didymella rabiei grew saprophytically on pieces of infested chickpea stems and pods, and formed pycnidia and pseudothecia. The extent of saprophytic growth and production of viable spores were determined by the incubation conditions. On debris left on the soil surface under natural conditions, the fungus rapidly colonized the tissues, formed abundant pseudothecia and pycnidia, and remained viable throughout the 2 years of the study. When plant debris was buried, D, rabiei was restricted to the original lesions, in which it formed new pycnidia and was viable for 2 to 5 months. Under controlled conditions in the laboratory, D. rabiei extensively colonized plant debris spread over the soil surface. On the other hand, the fungus did not grow on buried debris, or showed only very limited development when the artificially infested debris was buried between two layers of sterilized soil. Incubation temperature was the principal factor associated with the production of conidia and especially ascospores.     

Charge properties of mixtures of minerals with variable and constant surface charge

Surface charge of mixtures of lepidocrocite and illite determined by adsorption of potential-determining and electrolyte ions is studied as a function of pH and NaCl concentration. Deviations between results obtained by both methods were a function of the illite content of the mixtures, and can be mainly attributed to coatings of hydroxyaluminium complexes on the constant charge surfaces of the clay mineral, which can react with H⁺ ions or release exchange sites by precipitation of well-formed hydroxides. These coatings of aluminium complexes can cause H⁺ consumptions similar to those due to lepidocrocite. Some ideas are put forward for modelling charge properties of mixed systems.     

Resting metabolic rates increase with elevation in a mountain‐dwelling lizard

Individuals that inhabit broad elevational ranges may experience unique environmental challenges. Because temperature decreases with increased elevation, the ectotherms living at high elevations have to manage limited activity time and high thermoregulatory effort. The resting metabolic rate (RMR) of a postabsorptive animal is related to its total energy requirements as well as many other fitness traits. Mesquite lizards (Sceloporus grammicus) living on La Malinche Volcano, Mexico, inhabit a wide elevational range with some populations apparently thriving above the tree line. We measured the RMR of lizards from different elevations (i.e., 2,600, 3,200, and 4,100 m) at four ecologically relevant temperatures (i.e., 15, 25, 30, and 35 °C) and found that RMR of mesquite lizards increased with temperature and body mass. More importantly, lizards from the high‐elevation population had mass specific RMR that was higher at all temperatures. While the higher RMRs of high‐elevation populations imply higher metabolic costs at a given temperature these lizards were also smaller. Both of these traits may allow these high elevation populations to thrive in the face of the thermal challenges imposed by their environment.     

Optimization of the protein fraction of microcapsules used in feeding of marine fish larvae using in vitro digestibility techniques

The development of artificial feeds for marine fish larvae is demanding and, taking into account the difficulties and costs associated with the rearing of the larvae of some fish, preliminary evaluation of feed ingredients using in vitro techniques may be an alternative to in vivo assays. Some proteins used in microfeeds for marine fish were tested in vitro for examination of their effect on the proteases of seabream larvae. Casein and cuttlefish meal did not affect protease activity of crude larval extracts, whereas ovalbumin produced a 60% inhibition. The use of a pH-stat for the assessment of the degree of hydrolysis (DH) of proteins confirmed the low nutritive value of ovalbumin, since a much lower value was obtained for microcapsules prepared using this protein source when compared with those prepared using casein or cuttlefish meal (3.2 vs. 7.3 and 7.6, respectively). Products resulting from such hydrolysis were analysed using sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE). Image analysis of such gels led to the formulation of an index named the coefficient of protein degradation (CPD) which expressed the extent to which the main protein fractions were hydrolysed by larval proteases in a given time. A significant correlation ( r ² = 0.98, P  < 0.05) was obtained between DH and CPD values measured for either protein sources or microcapsules. The combination of protease inhibition assays with measurements of DH and CPD is proposed as a preliminary evaluation of protein ingredients used in the formulation of artificial feeds for larval fish.