The Unconventional Xer Recombination Machinery of Streptococci/Lactococci

Homologous recombination between circular sister chromosomes during DNA replication in bacteria can generate chromosome dimers that must be resolved into monomers prior to cell division. In Escherichia coli, dimer resolution is achieved by site-specific recombination, Xer recombination, involving two paralogous tyrosine recombinases, XerC and XerD, and a 28-bp recombination site (dif) located at the junction of the two replication arms. Xer recombination is tightly controlled by the septal protein FtsK. XerCD recombinases and FtsK are found on most sequenced eubacterial genomes, suggesting that the Xer recombination system as described in E. coli is highly conserved among prokaryotes. We show here that Streptococci and Lactococci carry an alternative Xer recombination machinery, organized in a single recombination module. This corresponds to an atypical 31-bp recombination site (difSL) associated with a dedicated tyrosine recombinase (XerS). In contrast to the E. coli Xer system, only a single recombinase is required to recombine difSL, suggesting a different mechanism in the recombination process. Despite this important difference, XerS can only perform efficient recombination when difSL sites are located on chromosome dimers. Moreover, the XerS/difSL recombination requires the streptococcal protein FtsKSL, probably without the need for direct protein-protein interaction, which we demonstrated to be located at the division septum of Lactococcus lactis. Acquisition of the XerS recombination module can be considered as a landmark of the separation of Streptococci/Lactococci from other firmicutes and support the view that Xer recombination is a conserved cellular function in bacteria, but that can be achieved by functional analogs

Multi-Institutional Evaluation of Pathologists' Assessment Compared to Immunoscore.

BACKGROUND The Immunoscore (IS) is a quantitative digital pathology assay that evaluates the immune response in cancer patients. This study reports on the reproducibility of pathologists' visual assessment of CD3+- and CD8+-stained colon tumors, compared to IS quantification. METHODS An international group of expert pathologists evaluated 540 images from 270 randomly selected colon cancer (CC) cases. Concordance between pathologists' T-score, corresponding hematoxylin-eosin (H&E) slides, and the digital IS was evaluated for two- and three-category IS. RESULTS Non-concordant T-scores were reported in more than 92% of cases. Disagreement between semi-quantitative visual assessment of T-score and the reference IS was observed in 91% and 96% of cases before and after training, respectively. Statistical analyses showed that the concordance index between pathologists and the digital IS was weak in two- and three-category IS, respectively. After training, 42% of cases had a change in T-score, but no improvement was observed with a Kappa of 0.465 and 0.374. For the 20% of patients around the cut points, no concordance was observed between pathologists and digital pathology analysis in both two- and three-category IS, before or after training (all Kappa < 0.12). CONCLUSIONS The standardized IS assay outperformed expert pathologists' T-score evaluation in the clinical setting. This study demonstrates that digital pathology, in particular digital IS, represents a novel generation of immune pathology tools for reproducible and quantitative assessment of tumor-infiltrated immune cell subtypes

A Defined Terminal Region of the E. coli Chromosome Shows Late Segregation and High FtsK Activity

Background: The FtsK DNA-translocase controls the last steps of chromosome segregation in E. coli. It translocates sister chromosomes using the KOPS DNA motifs to orient its activity, and controls the resolution of dimeric forms of sister chromosomes by XerCD-mediated recombination at the dif site and their decatenation by TopoIV. Methodology: We have used XerCD/dif recombination as a genetic trap to probe the interaction of FtsK with loci located in different regions of the chromosome. This assay revealed that the activity of FtsK is restricted to a,400 kb terminal region of the chromosome around the natural position of the dif site. Preferential interaction with this region required the tethering of FtsK to the division septum via its N-terminal domain as well as its translocation activity. However, the KOPSrecognition activity of FtsK was not required. Displacement of replication termination outside the FtsK high activity region had no effect on FtsK activity and deletion of a part of this region was not compensated by its extension to neighbouring regions. By observing the fate of fluorescent-tagged loci of the ter region, we found that segregation of the FtsK high activity region is delayed compared to that of its adjacent regions. Significance: Our results show that a restricted terminal region of the chromosome is specifically dedicated to the last step

De l’idée au marché : l’ITERG renforce ses activités dans la chimie verte avec la plateforme CEDOP, Centre européen de développement des oléo-produits

ITERG, the Industrial Technical Centre (CTI) for Fats and Oils, under the supervision of the Ministry of Economy, Finance and Employment, located in Pessac has undertaken the project to build a technology platform (to be operational in early 2012) dedicated to innovation and transfer in the field of oleochemicals from experimental to semi-industrial scales. This platform, CEDOP (European Centre for the Development of Oleo-Products) can offer within the same entity, expertise and scalability from laboratory to semi-industrial productions, to industrial manufacturers, processors, distributors and value chain actors of oleo-products. This project unique in its design, perfectly in tune with public policies for innovation and development of green chemistry, not only meets the needs of manufacturers and their markets but also the current socio-economic expectations in terms of environment and sustainable development. The CEDOP project total investment reached 8,700,000 € [buildings (laboratories, industrial and pilot halls, technical offices) and equipment]. After the positive results of preliminary studies (competition, market research, risk assessment) and the inclusion of CEDOP in the “State-Aquitaine Region Contract of Projects”, public institutions (Regional Council, State, FEDER, local) and professional organization (ONIDOL) brought together 85% of the project funding. Such a support reflects the confidence of the stakeholders in ITERG’s independent entrepreneurial skills in scientific and technology to meet public and professional policies, but above all in the large scope of corporate customers from different sectors of activity, potential future users of the tool. This project for research and technology transfer is fully integrated in ITERG’s development and diversification strategies and aims to develop an attractive lipochemistry-technology cluster

Imagerie Métabolique Rapide de Molécules Hyperpolarisées : à la Recherche du Temps Perdu

International audienc

Therapeutic Implications of the Immunoscore in Patients with Colorectal Cancer

International audienceFour decades were needed to progress from the first demonstration of the independent prognostic value of lymphocytes infiltration in rectal cancers to the first recommendation from the international guidelines for the use of a standardized immune assay, namely the “Immunoscore” (IS), to accurately prognosticate colon cancers beyond the TNM-system. The standardization process included not only the IS conceptualization, development, fine-tuning, and validation by a large international consortium, but also a demonstration of the robustness and reproducibility across the world and testing of international norms and their effects on the IS. This is the first step of a major change of paradigm that now perceives cancer as the result of contradicting driving forces, i.e., the tumor expansion and the immune response, interacting dynamically and influencing the prognosis and the response to therapies. This prompted us to evaluate and evidence the capacity of the tumor immune status, as reflected by the IS, to accurately predict chemotherapy responses in an international, randomized cohort study of colon cancer. Moreover, we developed a derived IS performed on initial diagnostic biopsies (ISB) to assess response levels to neoadjuvant therapies. In rectal cancer, ISB was positively correlated with the degree of histologic response to neoadjuvant chemoradiotherapy and identified - alone and even more accurately if combined with clinical data- patients eligible for a noninvasive strategy. Based on these results, we are currently setting up an international cohort for confirmation. The potential role of IS with immunotherapies must be anticipate

Correction de phase pour l'Imagerie Spectroscopique Rapide

International audienc

Correction de phase pour l'Imagerie Spectroscopique Rapide

International audienc