3 research outputs found
Analysis of the molecular basis of Xanthomonas axonopodis pv. citri pathogenesis in Citrus limon
Xanthomonas axonopodis pathovar citri (Xac) causes bacterial citrus
canker, a serious disease of most citrus species. Xanthomonas
campestris pv. campestris (Xcc) is the causal agent of black rot
disease in cruciferous plants. In Xcc, cell-cell signaling is mediated
by diffusible signal factor (DSF). Synthesis of DSF depends on RpfB and
RpfF. DSF perception and signal transduction have been suggested to
involve a two-component system comprising RpfC and RpfG. It has been
proposed that these proteins participate in a signal transduction
system linking changes in the environment to the synthesis of DSF and
the expression of virulence genes. Although the cluster of the rpf
genes in Xac has synteny with the corresponding cluster in Xcc, two
genes (rpfH and rpfI) are absent in Xac. To investigate DSF-mediated
regulation during Xac-Citrus limon interaction, we constructed two
strains of Xac, one with a mutation in the rpfF gene, leading to an
inability to produce DSF, and one with a mutation in the rpfC gene
leading to an overproduction of DSF. These mutants also show decreased
levels of extracellular cyclic \u3b2-(1,2)-glucans and decreased
production of endoglucanase and protease extracellular enzymes. The Xac
DSF-deficient rpfF and the DSF-hyper producing rpfC mutants are both
severely compromised in their ability to cause canker symptoms in lemon
leaves compared to the wild-type. Here we provide evidence that rpf
genes in Xac are involved in controlling virulence factors mediated by
DSF
Analysis of the molecular basis of Xanthomonas axonopodis pv. citri pathogenesis in Citrus limon
Xanthomonas axonopodis pathovar citri (Xac) causes bacterial citrus
canker, a serious disease of most citrus species. Xanthomonas
campestris pv. campestris (Xcc) is the causal agent of black rot
disease in cruciferous plants. In Xcc, cell-cell signaling is mediated
by diffusible signal factor (DSF). Synthesis of DSF depends on RpfB and
RpfF. DSF perception and signal transduction have been suggested to
involve a two-component system comprising RpfC and RpfG. It has been
proposed that these proteins participate in a signal transduction
system linking changes in the environment to the synthesis of DSF and
the expression of virulence genes. Although the cluster of the rpf
genes in Xac has synteny with the corresponding cluster in Xcc, two
genes (rpfH and rpfI) are absent in Xac. To investigate DSF-mediated
regulation during Xac-Citrus limon interaction, we constructed two
strains of Xac, one with a mutation in the rpfF gene, leading to an
inability to produce DSF, and one with a mutation in the rpfC gene
leading to an overproduction of DSF. These mutants also show decreased
levels of extracellular cyclic \u3b2-(1,2)-glucans and decreased
production of endoglucanase and protease extracellular enzymes. The Xac
DSF-deficient rpfF and the DSF-hyper producing rpfC mutants are both
severely compromised in their ability to cause canker symptoms in lemon
leaves compared to the wild-type. Here we provide evidence that rpf
genes in Xac are involved in controlling virulence factors mediated by
DSF
Outcomes from elective colorectal cancer surgery during the SARSâCoVâ2 pandemic
Aim
This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic.
Method
This was an international cohort study of patients undergoing elective resection of colon or rectal cancer without preoperative suspicion of SARS-CoV-2. Centres entered data from their first recorded case of COVID-19 until 19 April 2020. The primary outcome was 30-day mortality. Secondary outcomes included anastomotic leak, postoperative SARS-CoV-2 and a comparison with prepandemic European Society of Coloproctology cohort data.
Results
From 2073 patients in 40 countries, 1.3% (27/2073) had a defunctioning stoma and 3.0% (63/2073) had an end stoma instead of an anastomosis only. Thirty-day mortality was 1.8% (38/2073), the incidence of postoperative SARS-CoV-2 was 3.8% (78/2073) and the anastomotic leak rate was 4.9% (86/1738). Mortality was lowest in patients without a leak or SARS-CoV-2 (14/1601, 0.9%) and highest in patients with both a leak and SARS-CoV-2 (5/13, 38.5%). Mortality was independently associated with anastomotic leak (adjusted odds ratio 6.01, 95% confidence interval 2.58â14.06), postoperative SARS-CoV-2 (16.90, 7.86â36.38), male sex (2.46, 1.01â5.93), age >70 years (2.87, 1.32â6.20) and advanced cancer stage (3.43, 1.16â10.21). Compared with prepandemic data, there were fewer anastomotic leaks (4.9% versus 7.7%) and an overall shorter length of stay (6 versus 7 days) but higher mortality (1.7% versus 1.1%).
Conclusion
Surgeons need to further mitigate against both SARS-CoV-2 and anastomotic leak when offering surgery during current and future COVID-19 waves based on patient, operative and organizational risks