Evaluation de quatre milieux d'enrichissement pour la mise en évidence des salmonelles aviaires

During the course of one natural and two experimental infections with Salmonella the authors evaluated four different enrichment media for the isolation and growth of these organisms.

The final results indicate that the utilisation of only one medium is not sufficient. They suggest the addition of M.M. medium to the Sodium Tetrathionate and Selenite broth.

The M.S. medium proved to be too inhibiting.

     

Characterization of infectious bronchitis viruses isolated from outbreaks of disease in commercial flocks in Brazil

Fifteen isolations of infectious bronchitis (IB) virus were made from a total of 126 Brazilian poultry flocks of all ages that were examined. These flocks (14 chicken and 1 quail) were experiencing a variety of IB-like conditions including respiratory disease, digestive and kidney problems, and drops in egg production. One of the isolates was of the Massachusetts serotype. The remainder were examined by means of cross-neutralization tests in tracheal organ cultures and were shown to belong to at least four antigenic groups, all different from ones described previously in other countries. Some, but not all, of the flocks from which they were isolated had been vaccinated against IB with vaccines of the Massachusetts serotype. In vivo protection studies showed that the MA5 vaccine (of the Massachusetts serotype) protected well against challenge with four of these isolates, representing the different serotypes reported in this study.     

Intradermoreaction and hyposensitization in canine atopy

Results obtained from allergic skin testing and hyposensitization in 81 dogs are discussed.

The positive reactions encountered most frequently with intradermal testing were: house dust (88.9%), cotton (59.3%), moulds (53.1%), biting insects (47.0%), feathers (37.0%), kapok (35.8%) and grasses (35.8%).

Only dogs with constant and multiple sensitization were hyposensitized. The duration of treatment was eight months.

Hyposensitization gave good to excellent results in 76.5% of the animals treated. Some of these patients (53.0%) required a reduced dose of corticosteroids to relieve pruritus.

     

Natural extracts from pepper,wild rue and clove can activate defenses against pathogens in tomato plants

Tomato is an important species grown in many countries, either in fields or greenhouses. Despite decades of improvement, it is still susceptible to diseases, thus requiring the use of chemical pesticides, especially in greenhouses. Nevertheless it is imperative to reduce the use of environmental-unfriendly phytochemicals and favor less toxic tools to fight pathogens. Plants possess elaborate mechanisms against diseases that can lead to resistance. In the present work, we investigate the induction of plant defenses by means of extracts from plants widespread and easy to find, also known for their antimicrobial properties. Aqueous extracts of pepper ‘Rocoto’, wild rue and ethanolic extracts of clove powder (whose inhibiting effect was assessed on Oidium sp. spores) were tested on tomato plants for their ability to induce expression of different defense genes (PRs and regulatory proteins) after spraying. As revealed by RT-qPCR, all extracts were able to induce mRNA accumulation of different PR and MAPK regulators for several hours upon treatment, with clove and wild rue being the strongest. This effect could also be reproduced in tomato plants after a second treatment, 15 days after the first. The same extracts were tested in tomato and tobacco plants via leaf infiltration, showing necrotic symptoms associated with the hypersensitive response, thus confirming the priming capacity of the extracts. The involvement of salicylic acid (SA) in these responses was verified by HPLC analysis and in SA-depleted transgenic tobacco (NahG). The results obtained suggest that natural antimicrobial extracts can be used to induce plant defenses and protect valuable crops. At the same time these low-cost extracts do not pose a threat to the environment or the farmer and can help reduce the farming costs, especially in developing countries.     

Precision Farming Protocols: Part 1. Grid Distance and Soil Nutrient Impact on the Reproducibility of Spatial Variability Measurements

To determine temporal changes in soil nutrient status, reproducible results must be obtained at each time step. The objective of this paper was to determine the impact of grid distance on the reproducibility of spatial variability measurements. Soil samples from the 0 to 15 cm depth were collected from a 30 by 30 m grid in May 1995 in a 65 ha notill corn (Zea mays L.) field. Each bulk sample contained 15 individual cores, collected at sample points located every 11.4 cm along a transect that transversed 3 corn rows (57 cm). At each sampling point latitude, longitude, elevation, landscape position, and soil series were determined. The 30 m grid was used to develop 4 and 9 independent data sets having a 60 and 90 m, grids, respectively. Semivariograms, nugget to sill ratios, and mean squared errors were calculated for each data set. At 60 m: (i) the total N, total C, and pH semivariograms, of different start points, were similar, while semivariograms for Olsen P, K, and Zn were different; (ii) the spatial dependence ratings, based on the nugget to sill ratio, for total N, total C, and pH semivariograms were consistent and suggested moderate spatial dependence; (iii) the spatial dependence rating for Olsen P, K, and Zn for the 4 semivariograms were not consistent and ranged from weak to moderate spatial dependence. At 90 m all soil nutrients had different semivariograms for each start point, while the spatial dependence rating for each total N, total C, and pH start point were consistent and showed moderate spatial dependence. The total C, P, K, Zn, and pH MSE values at 60 m, were 30, 30, 41, 28, and 72% lower than the variance, respectively. This study showed that semivariogram, semivariance, MSE, and nugget to sill ratios reproducibility were dependent on soil nutrient and grid distance.     

Long-term cultivation impacts on selected soil properties in the northern Great Plains

Long-term cultivation impacts soil properties. During the early 1920s a study comparing non-cultivated and cultivated soils was done in eastern SD (Beadle, McCook, Minnehaha, and Union Counties), USA. The objectives of the current study were to: (1) determine the long-term (>80 years) impact of cultivation on selected soil properties; and (2) establish baseline soil data that can be used for future comparisons. Sample sites were located in well-drained summit and upper backslope positions. These topographic positions are strongly influenced by erosion processes from tillage, wind, and water. Previous studies at other locations in the region suggest that one might expect a loss of 10–20 cm of soil in >80 years of cultivation at these topographic positions. In the early 1920s the soils were tested for carbon (C) (total, organic, inorganic), total nitrogen (N), total sulfur (S), total calcium (Ca), total phosphorus (P), total potassium (K), and total magnesium (Mg). The 1920s study sites were resampled at 0–15, 15–50, and 50–100 cm depths and analyzed for C (total, organic, inorganic), N (total, nitrate-N), extractable P, extractable K, delta N (¹⁵N/¹⁴N or δ¹⁵N) for total N, delta C (¹³C/¹²C or δ¹³C) for total C, and pH. Long-term cultivation (>80 years) in the northern Great Plains of the United States has caused many significant reductions in surface soil (0–15 cm) extractable P, extractable K, surface pH, total C, organic C, total N, and δ¹⁵N for total N. In addition, the organic C to total N ratio for the 15–50 cm depth of cultivated soils was significantly lower when compared to non-cultivated soils. Cultivation caused significant increases in nitrate-N, delta C, inorganic C, and in the total C to total N and inorganic C to total N ratios (15–100 cm depths). Soil properties varied significantly with increasing soil depth. Soil pH, δ¹³C for total C, inorganic C, total C to total N ratio, and inorganic C to total N ratio increased significantly as soil depth increased. Nitrate-N, extractable P, extractable K, δ¹⁵N for total N, organic C, and total N decreased significantly as soil depth increased. Soil carbon changes at the sample sites are a combined result of differences in the reference surface elevation, carbon mineralization, and redistribution of carbon due to erosion. Changes in soil nutrient levels reflect crop removal, leaching, erosion, and pedogenic processes.     

Electronic monitoring in fisheries: Lessons from global experiences and future opportunities

Since the beginning of the 21st century, electronic monitoring (EM) has emerged as a cost‐efficient supplement to existing catch monitoring programmes in fisheries. An EM system consists of various activity sensors and cameras positioned on vessels to remotely record fishing activity and catches. The first objective of this review was to describe the state of play of EM in fisheries worldwide and to present the insights gained on this technology based on 100 EM trials and 12 fully implemented programmes. Despite its advantages, and its global use for monitoring, progresses in implementation in some important fishing regions are slow. Within this context, the second objective was to discuss more specifically the European experiences gained through 16 trials. Findings show that the three major benefits of EM were as follows: (a) cost‐efficiency, (b) the potential to provide more representative coverage of the fleet than any observer programme and (c) the enhanced registration of fishing activity and location. Electronic monitoring can incentivize better compliance and discard reduction, but the fishing managers and industry are often reluctant to its uptake. Improved understanding of the fisher's concerns, for example intrusion of privacy, liability and costs, and better exploration of EM benefits, for example increased traceability, sustainability claims and market access, may enhance implementation on a larger scale. In conclusion, EM as a monitoring tool embodies various solid strengths that are not diminished by its weaknesses. Electronic monitoring has the opportunity to be a powerful tool in the future monitoring of fisheries, particularly when integrated within existing monitoring programmes.     

Comparing Sex Steroid Levels During the Annual Cycles of Rainbow Trout (Oncorhynchus mykiss) Diploid Female (XX) and Triploid Female (XXX) Genotypic Sex

In this study, the annual cycle of the gonadal steroids testosterone (T), 11‐ketotestosterone (11‐KT), 17β‐estradiol (E2) and 17α, 20β‐dihydroxy‐4‐pregnen‐3‐one (DHP) was determined using radioimmunoassay and then compared for two populations of rainbow trout, XX diploid females (n = 40) and XXX triploid females (n = 15). In females, E2 and DHP levels were found to be significantly related to body weight (r = 0.22513; p < 0.0001 and r = 0.15831; p > 0.001, respectively). In this group, E2 concentrations peaked in November (25.05 ng /ml), while maximum DHP levels, only measurable from October to April, were attained in February (64.14 ng /ml). No significant differences in hormone ranges related to egg output ability were observed. Finally, sex steroid concentrations were low in the triploid female XXX fish compared to the female XX population. Nevertheless, maximum T (33.85 ng /ml) and 11‐KT (32.35 ng /ml) levels were recorded in January, for XXX. The levels for these two hormones are relatively high and are also significantly associated (r = 0.8430; p < 0.0001). Diploid females showed significantly higher levels of E2 than triploids over the 12‐month study period. The female triploid fish produced the lowest steroid hormone levels, such that these would be the most suitable for human consumption.     

Effects of bolus injection of epinephrine and norepinephrine on systolic time intervals in stress-resistant and stress-susceptible pigs

Systolic time intervals were measured in 15 stress-susceptible (SS) pigs to derive regression equations to determine to what extent their ventricular functions differed from those of stress-resistant (SR) pigs. Regression analysis revealed that the RR interval was the variable that was significantly (P less than 0.01) related to electromechanical systole and left ventricular ejection time. The preejection period (PEP) was independent of the RR interval. A normal increase of all systolic time intervals with age, independent of the RR interval, was also observed in SR and SS pigs. The 55-kg SS pigs had a higher noradrenergic tone than did 15-kg and 90-kg SS pigs, because their mean arterial blood pressure was higher and because their index values for electromechanical systole and their PEP were shorter than those of SR pigs of the same body weights. The cardiovascular responses to biogenic amines were also different according to the degree of development and stress susceptibility. Changes in mean arterial pressure and PEP were not as pronounced after injections of epinephrine and norepinephrine (10(-8) mol/kg of body weight) were given. Subsequently, a decrease in cardiovascular responses to epinephrine and norepinephrine injections in 90-kg SS pigs were recorded. These results indicate that 55-kg SS pigs have a higher level of circulating catecholamines and that the myocardium becomes less sensitive to epinephrine and norepinephrine after it is chronically exposed to these amines.