Mastitis diagnostics and performance monitoring: a practical approach

In this paper a review is given of frequently used mastitis diagnostic methods in modern dairy practice. Methods used at the quarter, cow, herd and regional or national level are discussed, including their usability for performance monitoring in udder health. Future developments, such as systems in which milk-derived parameters are combined with modern analytical techniques, are discussed. It is concluded that, although much knowledge is available and science is still developing and much knowledge is available, it is not always fully exploited in practice

Reproducing an ecosystem to measure nanoparticle impact

International audienceno abstrac

Physico-chemical study of fouling mechanisms of ultrafiltration membrane on Biwa lake (Japan)

Many studies have been undertaken to understand the fouling of the ultrafiltration membranes in drinking water treatment. Physico-chemical fouling of membranes depends on characteristics of the raw water and membrane surface properties. In the case of Biwa lake, some chemical parameters as Si and Fe concentrations change with temperature (season) causing irreversible fouling. While some exist on the influence of the particle mineralogy on the fouling, little work has been developed to elucidate the relation between the physicochemical complexity of the cake and the fouling. Generally clays or oxides are known to lead to a reversible fouling. In this work, the interactions between a UF organic membrane with minerals leading to a hardly reversible fouling are studied. In the case of the :Biwa lake water, fouling of ultrafiltration membranes results from the formation of a Si-rich ferric gel directly deposited on the membrane surface and a secondary allophanic gel layer at a bigger distance. The deposit nature and the membrane/cake interactions were studied using infra-red, X-ray diffraction, Al and Si NMR and EXAFS technics. The effect of mineral particles, especially ferric oxides associated with silica, has been demonstrated. The formation of FeSi gel directly on the membrane surface is mainly responsible for the fouling. The change of these particles is less negative than the membrane surface. The structure of such a material is complex. The low permeability of the gel is at the prime origin of the fouling

Differentially expressed genes in Bordetella pertussis strains belonging to a lineage which recently spread globally

Pertussis is a highly contagious, acute respiratory disease in humans caused by the Gram-negative pathogen Bordetella pertussis. Pertussis has resurged in the face of intensive vaccination and this has coincided with the emergence of strains carrying a particular allele for the pertussis toxin promoter, ptxP3, which is associated with higher levels of pertussis toxin (Ptx) production. Within 10 to 20 years, ptxP3 strains have nearly completely replaced the previously dominant ptxP1 strains resulting in a worldwide selective sweep. In order to identify B. pertussis genes associated with the selective sweep, we compared the expression of genes in ptxP1 and ptxP3 strains that are under control of the Bordetella master virulence regulatory locus (bvgASR). The BvgAS proteins comprise a two component sensory transduction system which is regulated by temperature, nicotinic acid and sulfate. By increasing the sulfate concentration, it is possible to change the phase of B. pertussis from virulent to avirulent. Until recently, the only distinctive phenotype of ptxP3 strains was a higher Ptx production. Here we identify additional phenotypic differences between ptxP1 and ptxP3 strains which may have contributed to its global spread by comparing global transcriptional responses under sulfate-modulating conditions. We show that ptxP3 strains are less sensitive to sulfate-mediated gene suppression, resulting in an increased production of the vaccine antigens pertactin (Prn) and Ptx and a number of other virulence genes, including a type III secretion toxin, Vag8, a protein involved in complement resistance, and lpxE involved in lipid A modification. Furthermore, enhanced expression of the vaccine antigens Ptx and Prn by ptxP3 strains was confirmed at the protein level. Identification of genes differentially expressed between ptxP1 and ptxP3 strains may elucidate how B. pertussis has adapted to vaccination and allow the improvement of pertussis vaccines by identifying novel vaccine candidates