Cell cycle control in Alphaproteobacteria.

NlmCategory="UNASSIGNED">Alphaproteobacteria include many medically and environmentally important organisms. Despite the diversity of their niches and lifestyles, from free-living to host-associated, they usually rely on very similar mechanisms to control their cell cycles. Studies on Caulobacter crescentus still lay the foundation for understanding the molecular details of pathways regulating DNA replication and cell division and coordinating these two processes with other events of the cell cycle. This review highlights recent discoveries on the regulation and the mode of action of conserved global regulators and small molecules like c-di-GMP and (p)ppGpp, which play key roles in cell cycle control. It also describes several newly identified mechanisms that modulate cell cycle progression in response to stresses or environmental conditions.

Bartonella apis sp. nov., a honey bee gut symbiont of the class Alphaproteobacteria.

Here, we report the culture and characterization of an alphaproteobacterium of the order Rhizobiales, isolated from the gut of the honey bee Apis mellifera. Strain PEB0122T shares >95 % 16S rRNA gene sequence similarity with species of the genus Bartonella, a group of mammalian pathogens transmitted by bloodsucking arthropods. Phylogenetic analyses showed that PEB0122T and related strains from the honey bee gut form a sister clade of the genus Bartonella. Optimal growth of strain PEB0122T was obtained on solid media supplemented with defibrinated sheep blood under microaerophilic conditions at 35-37 °C, which is consistent with the cultural characteristics of other species of the genus Bartonella. Reduced growth of strain PEB0122T also occurred under aerobic conditions. The rod-shaped cells of strain PEB0122T had a mean length of 1.2-1.8 μm and revealed hairy surface structures. Strain PEB0122T was positive for catalase, cytochrome c oxidase, urease and nitrate reductase. The fatty acid composition was comparable to those of other species of the genus Bartonella, with palmitic acid (C16 : 0) and isomers of 18- and 19-carbon chains being the most abundant. The genomic DNA G+C content of PEB0122T was determined to be about 45.5 mol%. The high 16S rRNA gene sequence similarity with species of Bartonella and its close phylogenetic position suggest that strain PEB0122T represents a novel species within the genus Bartonella, for which we propose the name Bartonella apis sp. nov. The type strain is PEB0122T ( = NCIMB 14961T = DSM 29779T).

DNA Topoisomerase I Gene Copy Number and mRNA Expression Assessed as Predictive Biomarkers for Adjuvant Irinotecan in Stage II/III Colon Cancer.

PURPOSE: Prospective-retrospective assessment of theTOP1gene copy number andTOP1mRNA expression as predictive biomarkers for adjuvant irinotecan in stage II/III colon cancer. EXPERIMENTAL DESIGN: Formalin-fixed, paraffin-embedded tissue microarrays were obtained from an adjuvant colon cancer trial (PETACC3) where patients were randomized to 5-fluorouracil/folinic acid with or without additional irinotecan.TOP1copy number status was analyzed by fluorescencein situhybridization (FISH) using aTOP1/CEN20 dual-probe combination.TOP1mRNA data were available from previous analyses. RESULTS: TOP1FISH and follow-up data were obtained from 534 patients.TOP1gain was identified in 27% using a single-probe enumeration strategy (≥4TOP1signals per cell) and in 31% when defined by aTOP1/CEN20 ratio ≥ 1.5. The effect of additional irinotecan was not dependent onTOP1FISH status.TOP1mRNA data were available from 580 patients with stage III disease. Benefit of irinotecan was restricted to patients characterized byTOP1mRNA expression ≥ third quartile (RFS: HRadjusted, 0.59;P= 0.09; OS: HRadjusted, 0.44;P= 0.03). The treatment byTOP1mRNA interaction was not statistically significant, but in exploratory multivariable fractional polynomial interaction analysis, increasingTOP1mRNA values appeared to be associated with increasing benefit of irinotecan. CONCLUSIONS: In contrast to theTOP1copy number, a trend was demonstrated for a predictive property ofTOP1mRNA expression. On the basis ofTOP1mRNA, it might be possible to identify a subgroup of patients where an irinotecan doublet is a clinically relevant option in the adjuvant setting of colon cancer.Clin Cancer Res; 22(7); 1621-31. ©2015 AACR.

Permissivity of fish cell lines to three Chlamydia-related bacteria: Waddlia chondrophila, Estrella lausannensis and Parachlamydia acanthamoebae.

Epitheliocystis is an infectious disease affecting gills and skin of various freshwater and marine fishes, associated with high mortality and reduced growth of survivors. Candidatus Piscichlamydia salmonis and Clavochlamydia salmonicola have recently been identified as aetiological agents of epitheliocystis in Atlantic Salmon. In addition, several other members of the Chlamydiales order have been identified in other fish species. To clarify the pathogenicity of Chlamydia-like organisms towards fishes, we investigated the permissivity of two fish cell lines, EPC-175 (Fathead Minnow) and RTG-2 (rainbow trout) to three Chlamydia-related bacteria: Waddlia chondrophila, Parachlamydia acanthamoebae and Estrella lausannensis. Quantitative PCR and immunofluorescence demonstrated that W. chondrophila and, to a lesser extent, E. lausannensis were able to replicate in the two cell lines tested. Waddlia chondrophila multiplied rapidly in its host cell and a strong cytopathic effect was observed. During E. lausannensis infection, we observed a limited replication of the bacteria not followed by host cell lysis. Very limited replication of P. acanthamoebae was observed in both cell lines tested. Given its high infectivity and cytopathic effect towards fish cell lines, W. chondrophila represents the most interesting Chlamydia-related bacteria to be used to develop an in vivo model of epitheliocystis disease in fishes.