Molecular typing of Mycoplasma agalactiae: tracing European-wide genetic diversity and an endemic clonal population

Mycoplasma agalactiae causes chronic infections in small ruminants and remains endemic in many regions of the world, despite intensive and costly eradication programs. In this study, the innate genomic plasticity of M. agalactiae was exploited to design and assess a combination of molecular epidemiological tools to trace the pathogen in different geographic locations and to understand its emergence or re-emergence after eradication campaigns. For this purpose, two collections of M. agalactiae isolates, representing European outbreaks or localized endemic disease in a single region of France, were subjected to RFLP (Restriction Fragment Length Polymorphism) analyses using two sets of DNA probes (distributed across the genome and specific for the vpma gene locus), and a previously described VNTR (Variable Number Tandem Repeats) analysis. A combination of four genome-specific DNA probes and two VNTRs gave the highest discriminative power. Molecular typing revealed that, while isolates from diverse geographical origins fell into clearly different groups, the endemic disease repeatedly observed in the Western Pyrenees region over the past 30 years has been caused by a unique subtype of M. agalactiae. This indicates that the re-emergence of the pathogen after seemingly successful eradication programs is not due to the importation of exotic strains, but to the persistence of local reservoirs of infection.     

Assessing the impact of interfering organic matter on soil metaproteomic workflow

Soil organic matter (SOM) is biologically, chemically, and physically complex. As a major store of nutrients within the soil, it plays an important role in nutrient provision to plants. An enhanced understanding of SOM utilisation processes could underpin better fertiliser management for plant growth, with reduced environmental losses. Metaproteomics can allow the characterisation of protein profiles and could help gain insights into SOM microbial decomposition mechanisms. Here, we applied three different extraction methods to two soil types to recover SOM with different characteristics. Specifically, water-extractable organic matter, mineral-associated organic matter and protein-bound organic matter were targeted with the aim to investigate the metaproteome enriched in those extractions. As a proof-of-concept, replicated extracts from one soil were further analysed for peptide identification using liquid chromatography followed by tandem mass spectrometry. We employed a framework for mining mass spectra for both peptide assignment and fragmentation pattern characterisation. Different extracts were found to exhibit contrasting total protein and humic substance content for the two soils investigated. Overall, water extracts displayed the lowest humic substance content (in both soils) and the highest number of peptide identifications (in the soil investigated) with the most frequent peptide hits associated with diverse substrate/ligand binding proteins of Proteobacteria and derived taxa. Our framework also highlighted a strong peptidic signal in unassigned and unmatched spectra, information that is currently not captured by the pipelines employed in this study. Taken together, this work points to specific areas for optimisation in chromatography and mass spectrometry to adequately characterise SOM-associated metaproteomes.     

Basic principles of muscle development and growth in meat-producing mammals as affected by the insulin-like growth factor (IGF) system

This presentation aims to describe how the basic events in prenatal muscle development and postnatal muscle growth are controlled by the insulin-like growth factor system (IGF). The prenatal events (myogenesis) cover the rate of proliferation, the rate and extent of fusion, and the differentiation of three myoblast populations, giving rise to primary fibers, secondary fibers, and a satellite cell population, respectively. The number of muscle fibers, a key determinant of the postnatal growth rate, is fixed late in gestation. The postnatal events contributing to myofiber hypertrophy comprise satellite cell proliferation and differentiation, and protein turnover. Muscle cell cultures produce IGFs and IGF binding proteins (IGFBPs) in various degrees depending on the origin (species, muscle type) and state of development of these cells, suggesting an autocrine/paracrine mode of action of IGF-related factors. In vivo studies and results based on cell lines or primary cell cultures show that IGF-I and IGF-II stimulate both proliferation and differentiation of myoblasts and satellite cells in a time and concentration-dependent way, via interaction with type I IGF receptors. However, IGF binding proteins (IGFBP) may either inhibit or potentiate the stimulating effects of IGFs on proliferation or differentiation. During postnatal growth in vivo or in fully differentiated muscle cells in culture, IGF-I stimulates the rate of protein synthesis and inhibits the rate of protein degradation, thereby enhancing myofiber hypertrophy. The possible roles and actions of the IGF system in regulating and determining muscle growth as affected by developmental stage and age, muscle type, feeding levels, treatment with growth hormone and selection for growth performance are discussed.     

Seasonal patterns of cadmium accumulation in Arrhenatherum elatius (Poaceae): Influence of mycorrhizal and endophytic fungal colonisation

We investigated the influence of arbuscular mycorrhizae (AM) and dark septate fungi (DSF) colonisation on cadmium (Cd) accumulation in Arrhenatherum elatius from heavy metal-contaminated sites. AM colonisation disappeared when Cd concentrations in soil increased, while DSF infection was weak but constant throughout the experiment indicating that soil heavy metals are toxic to AM but not to DSF. AM colonisation was greatest when plant Cd concentrations were highest providing evidence that AM colonisation may influence Cd accumulation. In addition, the disappearance of AM and the concomitant reduction of Cd in shoots during seed maturation result in our suggestion that seasonal variation in AM may play a role in protecting developing seeds from soil pollution.     

Cellular pathogenesis in prion diseases

Prion diseases are characterised by neuronal loss, vacuolation (spongiosis), reactive astrocytosis, microgliosis and in most cases by the accumulation in the central nervous system of the abnormal prion protein, named PrP(Sc). In this review on the "cellular pathogenesis in prion diseases", we have chosen to highlight the main mechanisms underlying the impact of PrP(C)/PrP(Sc) on neurons: the neuronal dysfunction, the neuronal cell death and its relation with PrP(Sc) accumulation, as well as the role of PrP(Sc) in the microglial and astrocytic reaction.     

Estimating direct genetic and maternal effects affecting rabbit growth and feed efficiency with a factorial design

The aim of this experiment was to evaluate the significance of neonatal environment on feed efficiency. For that purpose, rabbits from a line selected for residual feed intake (RFI) during 10 generations (G10 kits) were cross‐fostered with non‐selected control does (i.e., G0 line), and reciprocally. In parallel, sibs were fostered by mothers from their original line. Nine hundred animals were raised in individual (N = 456) or collective (N = 320) cages. Traits analysed in this study were body weight at 32 days and at 63 days, average daily gain (ADG), feed intake between weaning and 63 days (FI), feed conversion ratio (FCR) and RFI. The maternal environment offered by does from the line selected for RFI deteriorated the FCR of the kits, independently of their line of origin, during fattening (+0.08 ± 0.02) compared to FCR of kits nursed by G0 does. The line, the type of housing and the batch were significant effects for all the measured traits: G10 kits were lighter than their G0 counterparts at 32 days (?82.9 ± 9 g, p < 0.0001) and at 63 days (?161 ± 16 g, p < 0.0001). They also had a lower ADG (?2.36 ± 0.36 g/day, p < 0.0001), RFI (?521 ± 24 g/day, p < 0.0001) and a lower FI (?855 ± 31 g, p < 0.0001), resulting in a more desirable feed efficiency (FCR: ?0.35 ± 0.02). There was no significant difference in the contrast of G10 and G0 performances between collective and individual/digestive cages (p > 0.22): ?2.35 g/day versus 2.94 g/day for ADG, ?0.39 versus ?0.40 for FCR, ?577 g versus ?565 g for RFI and ?879 g versus ?859 g for FI, respectively). Thus, no genotype‐by‐environment (housing) interaction is expected at the commercial level, that is, no re‐ranking of the animals due to collective housing.     

Immunohistochemical characterization of a hepatic neuroendocrine carcinoma in a cat.

A hepatic mass was identified in a 5-year-old, female mixed-breed cat that died spontaneously after a clinical history of progressive emaciation, ptyalism, and persistent coryza. At necropsy, a 7-cm-diameter, yellow-brown, firm, multilobulated tumor was identified in the liver. Microscopically, the mass consisted of neoplastic cells arranged in small, closely packed nests within a thin fibrovascular stroma. These cells were of medium sized and polygonal, with fine argyrophilic cytoplasmic granules. Nuclei were predominantly round with finely stippled chromatin and indistinct nucleoli. Mitotic figures were numerous. Immunohistochemically, most of the neoplastic cells were immunoreactive for chromogranin A, neuron-specific enolase (NSE), and cytokeratin AE1/AE3 and weakly labeled for synaptophysin. The tumor was negative for glial fibrillary acidic protein (GFAP), vimentin, and cytokeratins 5, 6, 8, and 17. Vascular emboli and intrahepatic micrometastasis were also identified with chromogranin A. All these features were consistent with a hepatic neuroendocrine carcinoma and emphasized the importance of using a panel of antibodies to diagnose such rare tumors.     

Degradability of amino acids in selected legume forages using the in situ nylon-bag technique

This study was conducted to determine the amino acid profiles and rumen degradability of amino acids of three cultivated forage legumes – velvet bean (Mucuna pruriens), cowpea (Vigna unguiculata) and silverleaf desmodium (Desmodium uncinatum) – using the in situ nylon-bag technique. Two Friesian cows fitted with 10-cm-diameter rumen cannulae on a complete dairy feed ration (19% crude-protein dairy meal and maize silage) were used. Silverleaf desmodium had significantly (p < 0.05) higher concentration of amino acids compared with cowpea and velvet bean. Aspartic acid showed the highest (p < 0.05) concentration in all legumes and cysteine showed the lowest concentration. Legume forage of cowpea showed the highest (p < 0.05) level of degradability of amino acid followed by silverleaf desmodium and then velvet bean. Readily and slowly degradable components in all amino acids were highest (p < 0.05) in cowpea followed by silverleaf desmodium and then velvet bean. Moreover, silverleaf and cowpea showed higher (p < 0.05) levels of effective degradability of amino acids (at outflow rates p = 0.02, 0.04 and 0.06 h^?1) than velvet bean. Total amino acid disappearance was the least in velvet bean, which suggests that it can be used to supply bypass protein to the duodenum of the ruminant animal.     

Micro-Spatial Variability of Soil Nitrate Following Nitrogen Fertilization and Drip Irrigation

Micro-spatial analysis of nitrate (NO₃), an environmental contaminant partially attributed to nitrogen fertilization, can be useful for estimating its distribution in soils. A study was conducted to determine the micro-spatial distribution of soil NO₃ using kriging and cokriging in a drip-irrigated and nitrogen-fertilized field. One hundred soil samples were collected in a regular grid pattern from a 10 m × 20 m plot, and analyzed for soil NO₃ and pH. The effect of reduced sample size on NO₃ estimation was also evaluated. The pH data indicated the soils were slightly acidic to neutral with log[NO₃] values ranging from 1.66 to 2.95. These parameters were inversely related; which was probably an attribute of soil nitrification process. Sample variograms and cross-variograms suggested that the spatial distribution of pH and log[NO₃] could be described by linear models in the area studied, as indicated by small MSE (mean sum error), and RKV (reduced kriging variance) values close to 1. Contour maps based on kriging and cokriging estimates indicated greater homogeneity of the variables in the south-north direction than the east-west, except for zones of high NO₃ and low pH in the north-central edge and north-east corner of the grid area. Cokriging of log[NO₃] estimation, using pH data, improved MSE, MSSE (mean sum square error), MKV (mean kriging variance), RKV, CEE (correlation between estimated data and error), CEM (correlation between estimated and measured data) by 46, 31, 30, 22, 96, and 98%, respectively, as compared to kriging. Lower cokriging variance for any estimated log[NO₃] value, as compared to the kriging analysis, indicated that cokriging provided more accurate estimates. With reduced sample observations (n) for NO₃ similar conclusions were obtained; and the estimation accuracy was maintained up to n >70. Cokriging analysis with reduced n also curtailed the analytical cost, and facilitated NO₃ estimation by means of pH, which was measured at a cheaper cost.