Molecular markers for detection of pathogenic Escherichia coli strains belonging to serogroups O 138 and O 139

Escherichia coli strains belonging to O-serogroup 138 and 139 are important as disease agents in pigs causing post-weaning diarrhea and edema disease. Several types of shiga toxin-producing O 138 and O 139 strains were isolated from diarrheic humans and from cattle and food of bovine origin. Serotyping is the current method for detection of O 138 and O 139 strains but its applicability can be limited due to the presence of capsules and capsular-like bacterial surface antigens and in the case of rough LPS. To overcome these difficulties for diagnosis, we have developed a specific PCR method suitable for detection of different types of O 138 and O 139 strains. The O-antigen gene clusters of E. coli O 138 and O 139 type strains were sequenced, and the genes were identified on the basis of homology. By screening against 186 E. coli and Shigella type strains, two genes specific to each of E. coli O 138 and O 139 were identified, respectively, and were tested on 15 clinical and environmental isolates of those two serogroups in a double-blind test. The sensitivity of the PCR assays was determined, and the detection limits were 2 pg per mul of chromosomal DNA and 2 CFU per 10 g of water or pork samples. PCR-based detection of O-antigen specific genes of E. coli O 138 and O 139 was shown to be accurate, highly sensitive and rapid, and is suggested as a new diagnostic tool for investigations of infections and outbreaks with these strains in animals and humans and for control of food.     

Comparing greenhouse sprayers: the dose-transfer process

Three sprayers were evaluated for their affect on retention and efficacy: a carbon dioxide powered high-volume sprayer, a DRAMM coldfogger, and an Electrostatic Spraying Systems (ESS) sprayer with air-assistance. The active ingredients used were spinosad and azadirachtin. The plant canopy was constructed in the greenhouse using potted soybeans (Glycine max (L) Merrill cr Pioneer 9392). Application efficacy with spinosad was assessed using thrips [Western flower thrips, Frankliniella occidentalis (Pergande)] and mite (two-spotted spider mite, Tetranychus urticae Koch) abundance on shoots and leaves. Application efficacy with azadirachtin was assessed using thrips and aphid (soybean aphid, Aphis glycines Matsumura) abundance on shoots and leaves. The atomization characteristics of each sprayer were measured using an Aerometrics phase/Doppler particle analyzer (PDPA) 100-1D. The results of four tests are presented. Two tests used each sprayer according to manufacturer recommendations. These are 'recommended volume' tests that confound differences in toxicant distribution caused by the sprayer with differences caused by changes in application volume. The other two tests were 'constant volume' tests in which all three sprayers were used to deliver the same application volume. Both types of test gave differences between sprayers in retention of toxicant, but only the recommended volume tests showed significant effects of the sprayers on pest abundance. We attribute this difference to the role played by changing application volumes in the dose-transfer process. The constant-volume tests showed that application equipment influences efficacy.     

Expression and localisation of claudin-1, -2, -3, -4, -5, -7 and -10 proteins in the normal canine mammary gland

The recently identified claudins are dominant components of tight junctions, responsible for cell adhesion, polarity and paracellular permeability. Certain claudins have been shown to have relevance in tumour development. The aim of the present study was to analyse the expression of claudin-1, -2, -3, -4, -5, -7 and -10 in normal canine mammary glands. Samples from the inguinal mammary regions of 20 non-castrated, 1-13 years old female dogs were studied. Immunohistochemical analysis was performed on conventional specimens and tissue microarrays. The results of the immunohistochemical reactions detecting claudins in tissue sections were photodocumented. The immunoreactivity of claudins was quantitatively analysed on digital images using Leica QWin morphometry software. Intense membranous immunolabelling was found for claudin-1, -3 and -7, intense membranous with non-granular cytoplasmic immunolabelling for claudin-2, moderate membranous immunolabelling for claudin-4 and -5, and weak membranous immunolabelling for claudin-10. The occurrence of tight junctions was confirmed by ultrathin section electron microscopy. The available data suggested that claudins might be proteins preserved throughout the evolution of mammals. The results of our study support the concept that they are indeed preserved, since the same type of claudins, in identical distribution, could be detected in our canine mammary tissue samples as could be found in human mammary tissue.     

Rising water table: A threat to sustainable agriculture in an irrigated semi-arid region of Haryana, India

The sustainability of the rice-wheat cropping system in an irrigated semi-arid area of Haryana State (India) is under threat due to the continuous rise in the poor quality groundwater table, which is caused by the geo-hydrological condition and poor irrigation water management. About 500,000 ha in the State are waterlogged and unproductive and the size of the waterlogged area is increasing. We analyse the hydrology and estimate seasonal net groundwater recharge in the study area. Rainfall is quite variable, particularly in the monsoon season, and the mean monthly reference evapotranspiration shows a high inter-annual variation, with values between 2.45 and 8.47 mm/day in December and May. Groundwater recharge analysis during the study period (1989-2008) reveals that percolation from irrigated fields is the main recharge component with 57% contribution to the total recharge. An annual groundwater table rise of 0.137 m has been estimated for the study area. As the water table has been rising continuously, suitable water management strategies such as increasing groundwater abstraction by installing more tubewells, using the groundwater conjunctively with good quality canal water, changes in cropping patterns, adoption of salt tolerant crops, changes in water-pricing policy, and matching water supply more closely with demand, are suggested to bring the water table down to a safe limit and to prevent further rising of the water table.     

Piping and erodibility of loessic soils in Bergisches Land,Nordrhein‐Westfalen

In soils derived from loess on a range land site in the Rhenish Slate Mountains pipes were found at 120—190 cm depth above denser solifluction material. The pipes were 5—30 cm wide and 15—30 cm high. Various soil physical and chemical properties were determined and checked for their suitability as piping indicators. Silt contents reached 808 g kg^—1 in the piped soil sections where bulk densities were low to medium in comparison with clay rich and denser horizons beneath. Aggregate stabilities indicated by dispersion features, percolation rates, and dispersion ratios were suitable parameters to indicate piping vulnerability. Organic carbon contents tended to be low in the piped horizons, but there was no relationship between base saturation, ESP or EC values, and piping in the investigated soils.