The Genome Characteristics and Predicted Function of Methyl-Group Oxidation Pathway in the Obligate Aceticlastic Methanogens, Methanosaeta spp

In this work, we report the complete genome sequence of an obligate aceticlastic methanogen, Methanosaeta harundinacea 6Ac. Genome comparison indicated that the three cultured Methanosaeta spp., M. thermophila, M. concilii and M. harundinacea 6Ac, each carry an entire suite of genes encoding the proteins involved in the methyl-group oxidation pathway, a pathway whose function is not well documented in the obligately aceticlastic methanogens. Phylogenetic analysis showed that the methyl-group oxidation-involving proteins, Fwd, Mtd, Mch, and Mer from Methanosaeta strains cluster with the methylotrophic methanogens, and were not closely related to those from the hydrogenotrophic methanogens. Quantitative PCR detected the expression of all genes for this pathway, albeit ten times lower than the genes for aceticlastic methanogenesis in strain 6Ac. Western blots also revealed the expression of fwd and mch, genes involved in methyl-group oxidation. Moreover, 13C-labeling experiments suggested that the Methanosaeta strains might use the pathway as a methyl oxidation shunt during the aceticlastic metabolism. Because the mch mutants of Methanosarcina barkeri or M. acetivorans failed to grow on acetate, we suggest that Methanosaeta may use methyl-group oxidation pathway to generate reducing equivalents, possibly for biomass synthesis. An fpo operon, which encodes an electron transport complex for the reduction of CoM-CoB heterodisulfide, was found in the three genomes of the Methanosaeta strains. However, an incomplete protein complex lacking the FpoF subunit was predicted, as the gene for this protein was absent. Thus, F420H2 was predicted not to serve as the electron donor. In addition, two gene clusters encoding the two types of heterodisulfide reductase (Hdr), hdrABC, and hdrED, respectively, were found in the three Methanosaeta genomes. Quantitative PCR determined that the expression of hdrED was about ten times higher than hdrABC, suggesting that hdrED plays a major role in aceticlastic methanogenesis

Mechanisms of T cell organotropism

F.M.M.-B. is supported by the British Heart Foundation, the Medical Research Council of the UK and the Gates Foundation

Risk Factors for Anastomotic Leak After Colon Resection for Cancer

[EN] Objective: To determine pre-/intraoperative risk factors for anastomotic leak after colon resection for cancer and to create a practical instrument for predicting anastomotic leak risk. Background: Anastomotic leak is still the most dreaded complication in colorectal surgery. Many risk factors have been identified to date, but multicentric prospective studies on anastomotic leak after colon resection are lacking. Methods: Fifty-two hospitals participated in this prospective, observational study. Data of 3193 patients, operated for colon cancer with primary anastomosis without stoma, were included in a prospective online database (September 2011-September 2012). Forty-two pre-/intraoperative variables, related to patient, tumor, surgical procedure, and hospital, were analyzed as potential independent risk factors for anastomotic leak (60-day follow-up). A nomogram was created to easily predict the risk of anastomotic leak for a given patient.The study was promoted by the "Spanish Association of Surgeons" ("Asociacion Espanola de Cirujanos"). The online database was created and maintained by "Oxon Epidemiology," sponsored by Takeda.Frasson, M.; Flor, B.; Ramos, JL.; Granero-Castro, P.; Hervás-Marín, D.; Alvarez, MA.; Garcia, MJ.... (2015). Risk Factors for Anastomotic Leak After Colon Resection for Cancer: Multivariate Analysis and Nomogram From a Multicentric, Prospective, National Study With 3193 Patients. Annals of Surgery. 262(2):321-330. https://doi.org/10.1097/SLA.0000000000000973321330262