Evidence that a Leaf-Disk Test Allows Assessment of Isolate-Specific Resistance in Brassica oleracea Crops Against Downy Mildew (Peronospora parasitica)

A rapid resistance/susceptibility test for Peronospora parasitica (downy mildew) was established by inoculating leaf-disks of four Brassica oleracea accessions. Several conditions were tested: disk disinfection or not, agar medium with or without nutrients and with 50 or 100 ppm of benzimidazole. Using disinfected disks placed on agar (no nutrient and benzimidazole at 50 or 100 ppm), the responses of leaf-disks to four isolates were similar to those obtained using the classical cotyledon test, whereas undesired contaminations occurred in all other conditions. The possible effect of the particular leaf used for obtaining the disks was also studied. In each incompatible interaction tested, disks were resistant whatever the leaf used. In compatible interactions, susceptible phenotypes were observed on disks derived from the six lowest leaves, but disks from upper leaves were resistant. The genetic basis of resistance in a F1 hybrid broccoli was assessed, by testing six isolates on an F2 population derived from this hybrid. The cotyledon test only allows inoculation of two isolates per seedling, whereas many isolates can be tested on each plant by using leaf-disks. The segregation of the resistance to each of the six isolates was analysed: two dominant genes (tightly linked) control resistance to all isolates (one to five isolates; the other to only one isolate).     

Evaluation of β‐carotene assimilation in leopard geckos (Eublepharis macularius)

Although leopard geckos (Eublepharis macularius) are commonly kept under human care, their vitamin requirements are largely unknown. Many invertebrate preys display a low vitamin A concentration; thus, gut‐loading insects with vitamin A or carotenoids is a common practice. The objective of this prospective experimental study was to investigate whether dietary supplementation with β‐carotene, including prey gut‐loading, leads to sufficient vitamin A hepatic storage and prevents epithelial squamous metaplasia development in leopard geckos. Ten clinically healthy female leopard geckos were randomly divided in two groups with various supplementations: a group receiving vitamin A supplementation and a group receiving β‐carotene. Insects were gut‐loaded continuously with a supplement containing vitamin A or β‐carotene, depending on the group. Oral supplementation with cod liver oil or carrot juice was administered weekly to each lizard from “vitamin A group” and “carotenoid group” respectively. After 10 weeks of supplementation, surgical hepatic biopsies were obtained in three geckos of each group while the two remaining geckos were euthanized to undergo complete necropsy. Hepatic vitamin A concentration was determined for each lizard (n = 10) by ultra‐performance liquid chromatography. Histopathology revealed hepatocellular vacuolization and vitellogenic follicles in five females. Epithelial squamous metaplasia was not observed in any of the geckos. Hepatic vitamin A concentration was significantly higher in the carotenoid‐supplemented group than in the vitamin A‐supplemented group (p = 0.03). Our results suggest that in leopard geckos, dietary supplementation with β‐carotene allows sufficient vitamin A hepatic storage.     

Effect of feeding different sources of selenium on growth performance and antioxidant status of broilers

ABSTRACT

1. This study was conducted to determine the effect of different sources of selenium (Se) on breast and liver tissue deposition, apparent metabolisable energy (AME), growth performance and antioxidant status of broilers, measured as Se content in liver and breast tissues and glutathione peroxidase (GSH-Px) in blood, when used in 0–35 d broiler chicken diets.

2. A total of 200 male Ross 308 broilers were used in the feeding trial, which comprised two dietary phases, a starter from 0 to 21 d and finisher from 21 to 35 d of age. Four treatments with 10 replications each were used. A control diet (C) was formulated that was sufficient in protein and energy (230 and 215 g/kg of crude protein and 12.67 and 13.11 MJ/kg of metabolisable energy, respectively), for both phases, but contained background Se only from the feed ingredients. Diet 2 (IS) was supplemented with 10.35 g/t inorganic, elemental source of Se. Diet 3 (SY) was supplemented with 136.36 g/t selenised yeast, an organic source derived from Saccharomyces cerevisiae. Diet 4 (SS) was supplemented with 0.666 g/t sodium selenite, an inorganic source.

3. Birds fed the SY diet consumed less and weighed less than those fed IS or C (P < 0.05; 0–35 d of age), but there was no difference compared to birds fed SS diets. There were no differences in FCR or dietary AME between broilers fed different Se sources. All diets containing supplementary Se increased concentrations in the liver and breast muscle, and for GSH-Px levels in blood compared to birds fed the C diet (P < 0.001). Birds fed SY diets had greater Se levels in liver and breast tissues compared to birds fed any of the other diets (P < 0.001).

4. Diets supplemented with Se had variable effects on broiler growth performances and antioxidant status. Feeding Se from a yeast source has higher transfer into breast tissues. Feeding different sources and levels of Se to birds in a more challenging situation to induce oxidative stress may bring more conclusive results.     

Soil CO2 emission in sugarcane management systems

Sugarcane management systems affect soil attributes such as the carbon cycle. This fact has stimulated the sugar and alcohol industry to refine the sugarcane production systems by replacing the pre-harvest burning (PB) and manual harvest with mechanized harvesting followed by residue deposition. The aim of this study was to evaluate different management systems with respect to C cycling carbon dioxide and soil parameters (chemical, physical and biological) which were determined over the season. Three sugarcane cultivation systems were evaluated at the following periods: (a) PB, (b) 5-year green harvest and (c) 10-year green harvest. The results indicated that CO₂ emission was 36% greater in the 10-year sugarcane green harvest system than in the PB system. The bulk density and macroporosity were the factors that were most affected by the different sugarcane management systems and that significantly influenced soil CO₂ emissions. The principal component analysis showed that soil CO₂ emission was 18% influenced by base saturation (V%) and 14% by pH, especially in the PB area. Additionally, 19% was affected by carbon and macroporosity in the 5- and 10-year green harvest areas, respectively. From our results, it can be concluded that the most CO₂ emissions are in the areas of sugarcane green, this is due to the higher carbon concentration when compared with the area of burning sugarcane. The parameters that most influenced the CO₂ emissions were bulk density, porosity, macroporosity, pH and V%.     

Isolation,identification and antibiotic resistance of Campylobacter strains isolated from domestic and free-living pigeons

1. The aim of this study was to evaluate the occurrence of Campylobacter spp. in domestic and free-living pigeons and to evaluate the antibiotic resistance profiles.

2. The material consisted of cloacal swabs obtained from 108 homing pigeons and fresh faeces from 72 wild birds from Lublin and its vicinity. The identification of strains isolated on differential/selective media for Campylobacter spp. was carried out by MALDI-TOF and PCR. The susceptibility to antibiotics was evaluated by minimum inhibitory concentration (MIC) in Mueller-Hinton broth.

3. A total of 35 strains of Campylobacter spp. were isolated; 27 were identified as Campylobacter jejuni and 8 as Campylobacter coli. Over half of the isolates were resistant to erythromycin and streptomycin, 40% of strains were resistant to tetracycline and ampicillin and 37% isolates were resistant to amoxicillin. Resistance to two or more antibiotics was observed in all strains tested.

4. The results indicate that both domestic and free-living pigeons are reservoirs for bacteria of the genus Campylobacter, which are characterised by varied and growing resistance to commonly used antibiotics.     

Influence of three anesthetic protocols on glomerular filtration rate in dogs

OBJECTIVE: To investigate renal function in clinically normal dogs when awake and during anesthesia with medetomidine; xylazine, ketamine, and halothane (XKH) combination; or propofol. ANIMALS: 10 adult female Beagles. PROCEDURES: At intervals of 15 days, dogs were administered medetomidine (0.05 mg/kg, IV); XKH combination (xylazine [1 mg/kg, IV], ketamine [5 mg/kg, IV], and halothane [1% end-tidal concentration]); or propofol (6 mg/kg, IV) to induce anesthesia or no treatment. Glomerular filtration rate was assessed on the basis of renal uptake (RU; determined via renal scintigraphy) and plasma clearance (CL) of technetium 99m-labeled diethylenetriamine pentaacetic acid ((99m)Tc-DTPA). RESULTS: In awake dogs, mean +/- SEM RU was 9.7 +/- 0.4% and CL was 3.86 +/- 0.23 mL/min/ kg. Renal uptake and CL of (99m)Tc-DTPA were not significantly modified by administration of XKH (RU, 11.4 +/- 0.9%; CL, 4.6 +/- 0.32 mL/min/kg) or propofol (RU, 9.7 +/- 0.3%; CL, 3.78 +/- 0.37 mL/min/kg). Half-life elimination time of plasma (99m)Tc-DTPA decreased significantly in XKH-anesthetized dogs, compared with the value in awake dogs (14.4 minutes and 28.9 minutes, respectively). However, glomerular filtration rate was significantly decreased by administration of medetomidine (RU, 3.9 +/- 0.1%), and the time to maximum kidney activity was significantly increased (867 +/- 56 seconds vs 181 +/- 11 seconds without anesthesia). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that anesthesia with propofol or an XKH combination did not alter renal function in healthy Beagles, but anesthesia with medetomidine decreased early RU of (99m)Tc-DTPA.     

Identification of infrared absorption spectral characteristics of synovial fluid of horses with osteochondrosis of the tarsocrural joint

OBJECTIVE: To determine the feasibility of the use of Fourier-transform infrared (FTIR) spectroscopy within the midinfrared range to differentiate synovial fluid samples of joints with osteochondrosis from those of control samples. ANIMALS: 33 horses with osteochondrosis of the tarsocrural joint and 31 horses free of tarsocrural joint disease. PROCEDURES: FTIR spectroscopy of synovial fluid was used. Sixty-four synovial fluid samples from the tarsocrural joint were collected. Of these, 33 samples were from horses with radiographic evidence of osteochondrosis of the tarsocrural joint and 31 from control joints. Disease-associated features within infrared spectra of synovial fluid were statistically selected for spectral classification, and the variables identified were used in a classification model. Linear discriminant analysis and leave-one-out cross-validation were used to develop a classifier to identify joints with osteochondrosis. RESULTS: 12 significant subregions were identified that met the selection criteria. The stepwise discriminant procedure resulted in the final selection of 6 optimal regions that most contributed to the discriminatory power of the classification algorithm. Infrared spectra derived from synovial fluid of joints with osteochondrosis were differentiated from the control samples with accuracy of 77% (81% specificity and 73% sensitivity). CONCLUSIONS AND CLINICAL RELEVANCE: The disease-associated characteristics of infrared spectra of synovial fluid from joints with osteochondrosis may be exploited via appropriate feature selection and classification algorithms to differentiate joints with osteochondrosis from those of control joints. Further study with larger sample size including age-, breed-, and sex-matched control horses would further validate the clinical value of infrared spectroscopy for the diagnosis of osteochondrosis in horses.