Rational points over finite fields for regular models of algebraic varieties of Hodge type ≥1\geq 1

Let $R$ be a discrete valuation ring of mixed characteristics $(0,p)$, with finite residue field $k$ and fraction field $K$, let $k'$ be a finite extension of $k$, and let $X$ be a regular, proper and flat $R$-scheme, with generic fibre $X_K$ and special fibre $X_k$. Assume that $X_K$ is geometrically connected and of Hodge type $\geq 1$ in positive degrees. Then we show that the number of $k'$-rational points of $X$ satisfies the congruence $|X(k')| \equiv 1$ mod $|k'|$. Thanks to \cite{BBE07}, we deduce such congruences from a vanishing theorem for the Witt cohomology groups H^q(X_k, W\sO_{X_k,\Q}), for $q > 0$. In our proof of this last result, a key step is the construction of a trace morphism between the Witt cohomologies of the special fibres of two flat regular $R$-schemes $X$ and $Y$ of the same dimension, defined by a surjective projective morphism $f : Y \to X$.Comment: 85 pages. Refereed version. Signs have been modified in some definition

Diversity of Yersinia enterocolitica population in a slaughterhouse between 2009 and 2010 and discrimination ability of MLVA compared to PFGE

Yersiniosis is a human disease mainly due to the ingestion of raw or undercooked pork meat contaminated mostly with Yersinia enterocolitica (Ye). In France, 74.3% of pig batches at slaughterhouses carried pathogenic Ye. Among them, biotype 4 (BT4) and biotype 3 (BT3) were often recovered. PFGE is one of the most used methods to type Ye, with the restriction enzymes, XbaI and NotI. Nevertheless, MLVA method based on the diversity of six loci tends to replace PFGE; this method showed a higher discriminatory power in others studies. We investigated the genetic diversity of Ye strains isolated in 2009 and in 2010 in one pig slaughterhouse in France and compared the ability of MLVA and PFGE to discriminate the strains. During these two years, 335 isolates were collected from pigs. The BT4 represented 88.4% of the strains (296/335) and the BT3 only 11.6% (39/335). PFGE using XbaI enzyme allowed the identification of 12 XbaI-PFGE types and among them only one was common to the both surveys. Because the Simpson’s Index shows a low genetic diversity 31 BT4 strains and 39 BT3 strains were typed using MLVA. For BT3 strains, MLVA had the same index of diversity than PFGE (DI=0.472). In contrary, the index of diversity was significantly higher with MLVA (DI=0.871) than with PFGE (DI=0.665) for BT4 strains. Our study revealed that the population of Ye in pig varied over the time. The comparison of the both typing methods indicated that MLVA has a better discriminatory power than XbaI-PFGE method for BT4 strains but not for BT3 strains

In vitro characterization of the ability of Yersinia enterocolitica BT4 to colonize pigs and stainless steel surfaces

Yersiniosis is, after campylobacteriosis and salmonellosis, the third most frequently reported zoonosis in Europe. Humans become infected with Y. enterocolitica through the consumption of undercooked pork and raw food having been in contact with contaminated surfaces. Pigs, the main reservoir for human pathogenic strains, do not develop clinical signs. In France and worldwide, biotype 4 (BT4) is the biotype the most frequently isolated from both pigs and clinical yersiniosis. In this study, a collection of 26 pathogenic BT4 strains isolated from pig tonsils was used to investigate their ability to adhere and invade intestinal pig cells (IPEC-J2) and to adhere to abiotic surfaces (stainless steel coupons) using two in vitro tests. Regression analysis was performed between data sets obtained from IPECJ2 cells assays versus stainless steel assays. All BT4 strains were able to adhere and invade IPEC-J2 cells. However, the results showed heterogeneity between strains with respect to their ability to adhere to IPECJ2 cells, with a percentage of adhesion varying from 9% to more than 90%. The BT4 population displayed a more homogeneous ability to invade IPECJ2 cells with percentages varying from 10% to 26%. The BT4 strains displayed a great ability to adhere to the stainless steel surface, percentage of adhesion varying from 0.3% to 4.2%. No correlation was observed between IPEC-J2 cell adhesion, cell invasion and adhesion to the stainless steel surface (R² \u3c 0.02). In conclusion, these results reflect the ability of the different BT4 strains to colonize the intestinal tract of pigs and to contaminate the stainless steel surfaces of the food processing environment

New stable QTLs for berry weight do not colocalize with QTLs for seed traits in cultivated grapevine (Vitis vinifera L.)

International audienceBACKGROUND: In grapevine, as in other fruit crops, fruit size and seed content are key components of yield and quality; however, very few Quantitative Trait Loci (QTLs) for berry weight and seed content (number, weight, and dry matter percentage) have been discovered so far. To identify new stable QTLs for marker-assisted selection and candidate gene identification, we performed simultaneous QTL detection in four mapping populations (seeded or seedless) with various genetic backgrounds. RESULTS: For berry weight, we identified five new QTLs, on linkage groups (LGs) 1, 8, 11, 17 and 18, in addition to the known major QTL on LG 18. The QTL with the largest effect explained up to 31% of total variance and was found in two genetically distant populations on LG 17, where it colocalized with a published putative domestication locus. For seed traits, besides the major QTLs on LG 18 previously reported, we found four new QTLs explaining up to 51% of total variance, on LGs 4, 5, 12 and 14. The previously published QTL for seed number on LG 2 was found related in fact to sex. We found colocalizations between seed and berry weight QTLs only for the major QTL on LG 18 in a seedless background, and on LGs 1 and 13 in a seeded background. Candidate genes belonging to the cell number regulator CNR or cytochrome P450 families were found under the berry weight QTLs on LGs 1, 8, and 17. The involvement of these gene families in fruit weight was first described in tomato using a QTL-cloning approach. Several other interesting candidate genes related to cell wall modifications, water import, auxin and ethylene signalling, transcription control, or organ identity were also found under berry weight QTLs. CONCLUSION: We discovered a total of nine new QTLs for berry weight or seed traits in grapevine, thereby increasing more than twofold the number of reliable QTLs for these traits available for marker assisted selection or candidate gene studies. The lack of colocalization between berry and seed QTLs suggests that these traits may be partly dissociated