Potentiel microbiote résident dans les tissus de glande mammaire de vaches laitières prélevé en abattoir

Aseptic milking samples and microbiological analyses are used in routine for bovine mastitis diagnosis. Few papers treated about a resident microbiota in the ruminant healthy mammary gland tissues (Spuria et al., 2017), or about immunological consequences related with a such cohabitation (Rainard, 2017). In practice, it’s difficult to sample mammary gland tissues out of risks for cows health or milk production. We thus design a study based on samples taken at abattoir. It aimed at identify, quantify, compare the cow milk and mammary gland tissues microbiota of macroscopically healthy mammary glands, by classical microbiological analyses and by amplicon sequencing. We harvested thirteen couples of milk secretion and tissue samples, originated from the same quarter of reformed cows. Aseptic milking has been done just before culling and mammary gland tissues had been taken of the carcasses on slaughterline. Total and specific microbiological counting and metagenetic analysis were performed. Metagenetic analyses showed one main bacterial genus, Corynebacterium, generally found in the milk in higher proportions than in tissues. When it dominates clearly other populations in milk secretions, it can be found in the same quarter tissues. In case of identification of pathogenic bacteria in milk samples, the same pathogen were detected in tissues from the same quarters but in very different proportions: higher for Streptococcus uberis, lower for Staphylococcus spp or Enterococcus faecium. In tissues, Flavobacterium and Atopostipes genera were statistically more abundant than in milk. Data show also that species evenness and beta diversity are greater in mammary glands than in milk secretions. In opposition, species richness is higher in milk samples. These results show a potential resident microflora in mammary glands of culled cows in abattoirs. Metagenetic analysis of milk samples could be a good indicator of the udder microbiota and health in the future but our first results must be completed and confirmed on a larger number of samples. Hypothesis about nature of such a resident flora will have to be confirmed on producing cows before studying bacterial-host interactions. Rainard, P. 2017. Mammary microbiota of dairy ruminants: fact or fiction? Vet.Res., , 48 (25), 1-10. Spuria, L. et al. 2017. Microbial agents in macroscopically healthy mammary gland tissues of small ruminants. PeerJ, 5.MAMETA - Influence du microbiote sur la santé mammaire des vaches laitières en Walloni

Potential resident bacterial microbiota in udder tissues of culled cows sampled in abattoir

peer reviewedWhile mammary gland tissues (MGTs) are difficult to sample without risks for cow’s health or milk production, milk analysis are used in routine to assess dairy cow udder’s health. This study aimed to identify, quantify, compare the milk and MGTs microbiota of macroscopically healthy dairy bovine mammary glands (MG) in order to evaluate their degree of similarity. We harvested 13 couples of milk and MGTs samples, originated from the same quarter at culling. 16S rDNA Amplicon Sequencing was performed, showing Corynebacterium as the main bacterial genus in both types of samples but generally found in the milk in higher proportions than in tissues. Species evenness was higher in MGTs while species richness was higher in milk samples. Beta diversity was significantly different between both matrices suggesting the presence of a resident microbiota in MGTs of dairy cows at time of culling partially reflected by the milk microbiota from the same quarter

Skeletal-specific expression of Fgd1 during bone formation and skeletal defects in faciogenital dysplasia (FGDY; Aarskog syndrome)

FGD1 encodes a guanine nucleotide exchange factor (GEF) that specifically activates the Rho GTPase Cdc42; FGD1 mutations result in Faciogenital Dysplasia (FGDY, Aarskog syndrome), an X-linked developmental disorder that adversely affects the formation of multiple skeletal structures. To further define the role of FGD1 in skeletal development, we examined its expression in developing mouse embryos and correlated this pattern with FGDY skeletal defects. In this study, we show that Fgd 1, the mouse FGD1 ortholog, is initially expressed during the onset of ossification during embryogenesis. Fgd 1 is expressed in regions of active bone formation in the trabeculae and diaphyseal cortices of developing long bones. The onset of Fgd 1 expression correlates with the expression of bone sialo-protein, a protein specifically expressed in osteoblasts at the onset of matrix mineralization; an analysis of serial sections shows that Fgd 1 is expressed in tissues containing calcified and mineralized extracellular matrix. Fgd1 protein is specifically expressed in cultured osteoblast and osteoblast-like cells including MC3T3-E1 cells and human osteosarcoma cells but not in other mesodermal cells; immunohistochemical studies confirm the presence of Fgd1 protein in mouse calvarial cells. Postnatally, Fgd 1 is expressed more broadly in skeletal tissue with expression in the perichondrium, resting chondrocytes, and joint capsule fibroblasts. The data indicate that Fgd 1 is expressed in a variety of regions of incipient and active endochondral and intramembranous ossification including the craniofacial bones, vertebrae, ribs, long bones and phalanges. The observed pattern of Fgd 1 expression correlates with FGDY skeletal manifestations and provides an embryologic basis for the prevalence of observed skeletal defects. The observation that the induction of Fgd 1 expression coincides with the initiation of ossification strongly suggests that FGD1 signaling plays a role in ossification and bone formation; it also suggests that FGD1 signaling does not play a role in the earlier phases of skeletogenesis. With the observation that FGD1 mutations result in the skeletal dysplasia FGDY, accumulated data indicate that FGD1 signaling plays a critical role in ossification and skeletal development. © 2000 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35167/1/1015_ftp.pd

Insight into the structural determinants for selective inhibition of matrix metalloproteinases.

The matrix metalloproteinase (MMP) family has been a pharmaceutical target for over 20 years. Despite massive research and development efforts, only one MMP inhibitor (Periostat) has been approved by the FDA for the treatment of periodontal disease. Possible reasons for the low success rate of MMP inhibitors in the clinic include unwanted side effects caused by their lack of selectivity, poor oral bioavailability and decreased potency in vivo. We review how three-dimensional structures (3D) of MMP inhibitor complexes as well as the inhibition profile of compounds screened on MMP can be used to guide the optimization of selectivity of MMP inhibitors. Analysis of MMP 3D structures provides a ranking of their pockets on the basis of opportunities for selective interactions. One can use inhibition data to build pharmacophore or quantitative structure-activity models (QSAR) for virtual screening of libraries of novel MMP inhibitors. Combining protein- and ligand-based approaches, we conclude that targeting a single pocket is not always sufficient to achieve the desired selectivity profile. Finally, we also outline novel series of selective MMP inhibitors that exploit differences in the intrinsic flexibility of the catalytic domain to form selective interactions with a given MMP

The quest for novel chemical matter

Importance to the field: Identifying novel chemical matter is the focus of many drug discovery efforts. Computer-based de novo design of drug-like molecules has emerged as a valuable approach to identify novel chemical matter. De novo design aims to build in silico an entire molecule “from scratch”. It is complementary to other approaches such as high throughput screening, fragment-based screening or virtual screening. Areas covered in this review: Herein we discuss recent research efforts that aim to build in silico more chemically accessible molecules, to sample more efficiently the chemical space and to rank the proposed molecules. De novo design algorithms developed between 2008 and 2010 are also reviewed. We also discuss the issue of validation. Finally, we highlight some recent successful applications of de novo design to drug discovery projects. What the reader will gain: The reader is provided with an overview of the recent methodological developments and applications of de novo design. As a result, the reader will gain valuable insights into the challenges, the limitations and the opportunities of de novo design. Take home message: Research has addressed some of the limitations of the early versions of de novo design softwares, in particular the lack of synthetic accessibility of the proposed molecules. The lack of accurate function to score molecules generated within a binding site remains a major limitation. Large-scale validation studies are still missing. Despite these limitations, de novo design is a valuable approach to generate either chemical starting points or ideas