Détection moléculaire spécifique de la région vir du plasmide pTi d'Agrobacterium tumefaciens dans les sols et plants au Maroc

Le meilleur moyen de contrôle du crown gall ( Agrobacterium tumefaciens ) est la prévention et donc la détection de la bactérie pathogène dans les sols prévus pour les pépinières. Pour cela nous avons essayé une approche moléculaire utilisant la PCR pour caractériser le plasmide pTi par le couple des amorces spécifiques F14/F44 dans les sols de diverses régions marocaines. Cette technique de détection représente un indicateur potentiel d'avertissement sur l'état d'infection des sols et plants par A. tumefaciens qui permet ainsi de déclencher la lutte biologique par le NoGall, produit commercial australien, hébergeant l'antagoniste K₁₀₂₆.     

Serum antibody isotype responses of Fasciola-infected sheep and cattle to excretory and secretory products of Fasciola species

This study investigated the immunoglobulin isotype responses of sheep and cattle chronically infected with Fasciola hepatica and Fasciola gigantica to adult F. hepatica excretory/secretory products (Fh-ES) or F. gigantica excretory/secretory products (Fg-ES), respectively. An antibody enzyme-linked immunosorbent assay (Ab-ELISA) was used to determine serum antibody (total Ig, IgG(1), IgM, IgG(2) and IgA) responses. At necropsy, the mean number of flukes recovered was lower in cattle than in sheep. All F. hepatica and F. gigantica infected sheep and cattle showed an increased total Ig levels from 3 to 4 weeks post-infection (wpi). Among isotypes IgG(1) was most dominant while IgM was the earliest (2 wpi) to be detected in both sheep and cattle infected with both F. hepatica and F. gigantica animals. IgG(2) response was early (2 wpi) in sheep infected by F. hepatica but there was no response in sheep infected with F. gigantica. There was a late and strong IgG(2) response in cattle infected with both flukes. The IgA isotype showed an early and a clear biphasic response in sheep with F. hepatica but was less pronounced in F. gigantica infected sheep. While IgA response to Fh-ES was noticed 5 wpi in F. hepatica infected cattle, it appeared much later (21 wpi) in those infected with F. gigantica. The dominance of IgG(1) isotype in infected sheep and cattle suggest an associated Th2 response. This early response to adult Fasciola spp. ES antigen suggests an early exposure to the antigen presumably through the cross-reacting ES products of juvenile flukes. There is clearly difference in IgG(2) isotype response in cattle (resistant) compared to sheep (susceptible). The late IgG(2) response in cattle may suggest late Th1 involvement in bovine cellular responses to adult Fh-ES/Fg-ES.     

Inductively coupled plasma mass‐spectrometric determination of platinum in excretion products of client‐owned pet dogs

Residues of antineoplastic drugs in canine excretion products may represent exposure risks to veterinary personnel, owners of pet dogs and other animal care‐takers. The aim of this study was to measure the extent and duration of platinum (Pt) excretion in pet dogs treated with carboplatin. Samples were collected before and up to 21 days after administration of carboplatin. We used validated, ultra‐sensitive, inductively coupled plasma‐mass spectrometry assays to measure Pt in canine urine, faeces, saliva, sebum and cerumen. Results showed that urine is the major route of elimination of Pt in dogs. In addition, excretion occurs via faeces and saliva, with the highest amounts eliminated during the first 5 days. The amount of excreted Pt decreased over time but was still quantifiable at 21 days after administration of carboplatin. In conclusion, increased Pt levels were found in all measured excretion products up to 21 days after administration of carboplatin to pet dogs, with urine as the main route of excretion. These findings may be used to further adapt current veterinary guidelines on safe handling of antineoplastic drugs and treated animals.     

Total mercury levels in selected human tissues, Idaho-1973-74(1,2)

Total mercury levels were determined in human tissues taken at autopsy from six hospitals in the three basic geographical areas of Idaho. Of the 242 specimens analyzed, 76 percent contained detectable mercury. Levels were compared with respect to the age, sex, and geographic residence of autopsied individuals. Mean levels detected were 1.04 ppm in kidney tissue, 0.34 ppm in liver, and 0.08 ppm in brain. Mean mercury levels for the three geographical areas were: southeastern Idaho, 0.22 ppm; southwestern Idaho, 0.80 ppm; and northern Idaho, 0.43 ppm. The relatively high means in southwestern Idaho specimens may be related to the preponderance of natural cinnabar deposits in that portion of the State. Mercury levels were higher in women than men for all tissues in both the southwestern and northern areas, but the reverse was true in the southeast. Data were compared with findings of other investigators in an attempt to arrive at background levels of total mercury residues in human tissues.     

Automated identification of sugar beet diseases using smartphones

Cercospora leaf spot (CLS) poses a high economic risk to sugar beet production due to its potential to greatly reduce yield and quality. For successful integrated management of CLS, rapid and accurate identification of the disease is essential. Diagnosis on the basis of typical visual symptoms is often compromised by the inability to differentiate CLS symptoms from similar symptoms caused by other foliar pathogens of varying significance, or from abiotic stress. An automated detection and classification of CLS and other leaf diseases, enabling a reliable basis for decisions in disease control, would be an alternative to visual as well as molecular and serological methods. This paper presents an algorithm based on a RGB‐image database captured with smartphone cameras for the identification of sugar beet leaf diseases. This tool combines image acquisition and segmentation on the smartphone and advanced image data processing on a server, based on texture features using colour, intensity and gradient values. The diseases are classified using a support vector machine with radial basis function kernel. The algorithm is suitable for binary‐class and multi‐class classification approaches, i.e. the separation between diseased and non‐diseased, and the differentiation among leaf diseases and non‐infected tissue. The classification accuracy for the differentiation of CLS, ramularia leaf spot, phoma leaf spot, beet rust and bacterial blight was 82%, better than that of sugar beet experts classifying diseases from images. However, the technology has not been tested by practitioners. This tool can be adapted to other crops and their diseases and may contribute to improved decision‐making in integrated disease control.     

Identification of Mulberry Dwarf Phytoplasmas in the Genital Organs and Eggs of Leafhopper Hishimonoides sellatiformis

ABSTRACT The presence of mulberry dwarf (MD) phytoplasmas in organs of the inoculative vector insects Hishimonoides sellatiformis and Hishimonus sellatus was determined by means of electron microscopy (EM) and polymerase chain reaction (PCR) assays. Many MD phytoplasmas were detected in genital organs as well as in the intestines, salivary glands, brains, fat bodies, and thoracic ganglia of Hishimonoides sellatiformis, but only in the intestine and salivary glands of Hishimonus sellatus. Many phytoplasmas with characteristic morphology were observed via EM in ovaries, seminal receptacles, and testes, and they were further identified by PCR assays with group I-specific primers. In addition, the organisms were detected by direct or nested PCR assays in eggs (head pigmentation stage of embryos) laid on mulberry shoots by inoculative leafhoppers and in the newly hatched nymphs from these eggs. These findings indicate that transovarial transmission of MD phytoplasmas occurs in Hishimonoides sellatiformis.     

A Greenhouse Test for Screening Sugar Beet (Beta Vulgaris) for Resistance to Rhizoctonia Solani

Rhizoctonia solani Kühn is a serious plant pathogenic fungus, causing various types of damage to sugar beet (Beta vulgaris L.). In Europe, the disease is spreading and becoming a threat for the growing of this crop. Plant resistance seems to be the most practical and economical way to control the disease. Experiments were carried out to optimise a greenhouse procedure to screen plants of sugar beet for resistance to R. solani. In the first experiment, two susceptible accessions were evaluated for root and leaf symptoms, after being grown in seven different soil mixtures and inoculated with R. solani. The fungus infected all plants. It was concluded that leaf symptoms were not reliable for the rating of disease severity. Statistically significant differences between the soil mixtures were observed, and there were no significant differences between the two accessions. The two soil mixtures, showing the most severe disease symptoms, were selected for a second experiment, including both resistant and susceptible accessions. As in the first experiment, root symptoms were recorded using a 1–7 scale, and a significant expression of resistance was observed. The average severity of the disease in the greenhouse experiment generally was comparable with the infection in field experiments, and the ranking of the accessions was the same in the two types of experiments. It was concluded that evaluation procedures in the greenhouse could be used as a rapid assay to screen sugar beet plants for resistance to R. solani.     

Prevalence of mycoplasmas in the respiratory tracts of pneumonic calves.

The prevalence of mycoplasmas in the respiratory tracts of 148 pneumonic calves originating from 25 herds in the Netherlands is reported. Four types of culture media were used to isolate mycoplasmas: solid modified Edward medium, 2 types of Friis media, and A7B differential agar medium. Mycoplasmas were isolated both from nasal swab specimens and lung lavage fluids collected from live calves and from nasal mucosa and lung tissue specimens collected post mortem. All of the mycoplasma strains isolated could be identified as either Ureaplasma diversum (isolated from 80% of 25 herds), Mycoplasma dispar (92%), M. bovirhinis (88%), M. bovis (20%), M. bovigenitalium (4%), M. arginini (16%), or M. canis (12%). Isolation rates of M. dispar and U. diversum were considerably higher from lung lavage fluids than from nasal swab specimens. M. bovis was detected only in fattening herds and not in dairy herds. The respiratory tracts of 75% of the calves examined contained at least 2 mycoplasma species. In total, 25 different combinations of mycoplasma species were detected in specimens collected from noses and lungs. The pathogenic species U. diversum and M. dispar had not been isolated before in the Netherlands.     

Influence of the three RN genotypes on chemical composition, enzyme activities, and myofiber characteristics of porcine skeletal muscle.

An experiment was conducted to evaluate the effects of the RN genotype on skeletal muscle characteristics in pigs sharing otherwise the same polygenic background. Animals were genotyped for RN on the basis of RTN (Rendement Technologique Napole) records using segregation analysis methods. Samples of longissimus (L) and semispinalis capitis (S) muscles were taken from 39 rn+/rn+, 38 RN-/rn+ and 37 RN-/RN- pigs slaughtered at 108 +/- 8.6 kg live weight. Activities of lactate dehydrogenase (LDH), citrate synthase (CS), and beta-hydroxy-acyl-coenzyme A dehydrogenase (HAD) were measured on both muscles to assess glycolytic, oxidative, and lipid beta-oxidation capacities, respectively. Histological examinations and chemical analyses were performed on L muscle. The energetic metabolism of the white L muscle was more oxidative in RN-/RN- than in rn+/rn+ pigs, as shown by increased CS and HAD activities (P < .001), decreased LDH activity (P < .001), larger cross-sectional area of IIA (P < .05) and IIB-red (P < .05) fibers, higher relative area of IIA fibers ( P < .05), and lower relative area of IIB-white fibers (P < .001). No significant difference was found between heterozygous and homozygous carriers of the RN- allele, except for CS activity, which was lower in RN-/rn+ than in RN-/RN- pigs. In L muscle, the RN- allele led to a large increase in glycolytic potential (+3.5 phenotypic SD between homozygotes) and lightness (+.7 SD), and a decrease in ultimate pH, dry matter, and protein contents (-1.7 to -2 phenotypic SD for these three traits), with an almost completely dominant effect. No differences were found between genotypes for intramuscular fat and hydroxyproline contents. In the red S muscle, the presence of RN- had no influence on enzyme activities. These results indicate that the RN genotype greatly influences compositional and histochemical traits and metabolic enzyme activities in a muscle type-dependent manner, with a completely or incompletely dominant effect of the RN- allele.