scholarly journals The impact of Paenibacillus polymyxa HY96-2 luxS on biofilm formation and control of tomato bacterial wilt

2019 ◽  
Vol 103 (23-24) ◽  
pp. 9643-9657 ◽  
Author(s):  
Jincui Yi ◽  
Daojing Zhang ◽  
Yuejuan Cheng ◽  
Jingjing Tan ◽  
Yuanchan Luo
Keyword(s):  
Bacterial Wilt ◽  
Late Stage ◽  
Biofilm Formation ◽  
Early Stage ◽  
Regulatory Gene ◽  
Paenibacillus Polymyxa ◽  
Deletion Strain ◽  
Biocontrol Efficacy ◽  
The Impact ◽  
Tomato Bacterial Wilt

Abstract The focus of this study was to investigate the effects of luxS, a key regulatory gene of the autoinducer-2 (AI-2) quorum sensing (QS) system, on the biofilm formation and biocontrol efficacy against Ralstonia solanacearum by Paenibacillus polymyxa HY96-2. luxS mutants were constructed and assayed for biofilm formation of the wild-type (WT) strain and luxS mutants of P. polymyxa HY96-2 in vitro and in vivo. The results showed that luxS positively regulated the biofilm formation of HY96-2. Greenhouse experiments of tomato bacterial wilt found that from the early stage to late stage postinoculation, the biocontrol efficacy of the luxS deletion strain was the lowest with 50.70 ± 1.39% in the late stage. However, the luxS overexpression strain had the highest biocontrol efficacy with 75.66 ± 1.94% in the late stage. The complementation of luxS could restore the biocontrol efficacy of the luxS deletion strain with 69.84 ± 1.09% in the late stage, which was higher than that of the WT strain with 65.94 ± 2.73%. Therefore, we deduced that luxS could promote the biofilm formation of P. polymyxa HY96-2 and further promoted its biocontrol efficacy against R. solanacearum.

scholarly journals Hepatitis C virus enhances Rubicon expression, leading to autophagy inhibition and intracellular innate immune activation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yuto Shiode ◽  
Hayato Hikita ◽  
Satoshi Tanaka ◽  
Kumiko Shirai ◽  
Akira Doi ◽  
...  
Keyword(s):  
Immune Response ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Late Stage ◽  
Early Stage ◽  
Hcv Infection ◽  
Infected Cells ◽  
The Impact ◽  
Chronic Hepatitis C Patients

Abstract Autophagy, a degradation system, works to maintain cellular homeostasis. However, as the impact of Hepatitis C virus (HCV) infection on hepatocyte autophagy and its effect on HCV replication remain unclear, we examined them. HCV infection suppressed late-stage autophagy and increased Rubicon. siRNA-mediated knockdown of Rubicon promoted autophagy in HCV-infected cells. In Huh-7 cells harbouring the HCV replicon, Rubicon knockdown downregulated the expression of type 1 interferon (IFN)-related genes and upregulated HCV replication. Rubicon overexpression or administration of bafilomycin A1 or chloroquine, an inhibitor of late-stage autophagy, suppressed autophagy and activated the type 1 IFN pathway. On the other hand, Atg7 knockout suppressed early-stage autophagy and did not activate the type 1 IFN pathway. In livers of humanized liver chimeric mice, HCV infection increased Rubicon and enhanced type 1 IFN signalling. Elimination of HCV in the mice reduced the increase in Rubicon due to HCV infection. The expression levels of Rubicon and IFN-stimulated genes in chronic hepatitis C patients were higher than those in non-B, non-C hepatitis patients. HCV infection increased Rubicon and suppressed hepatocyte autophagy, leading to activation of the intracellular immune response. Rubicon induction is involved in HCV replication via activation of the intracellular immune response.

scholarly journals Paraquat Preferentially Induces Apoptosis of Late Stage Effector Lymphocyte and Impairs Memory Immune Response in Mice

2019 ◽  
Vol 16 (11) ◽  
pp. 2060 ◽  
Author(s):  
Yiming Shao ◽  
Yifan Zhao ◽  
Tingting Zhu ◽  
Fen Zhang ◽  
Xiuli Chang ◽  
...  
Keyword(s):  
Immune Response ◽  
Late Stage ◽  
Early Stage ◽  
Keyhole Limpet Hemocyanin ◽  
Primary Immune Response ◽  
Secondary Immune Response ◽  
Effector Cells ◽  
Memory Immune Response ◽  
The Impact

Paraquat (PQ) is a toxic non-selective herbicide. To date, the effect of PQ on memory immune response is still unknown. We investigated the impact of PQ on memory immune response. Adult C57BL/6 mice were subcutaneously injected with 2 mg/kg PQ, 20 mg/kg PQ or vehicle control every three days for two weeks. A single injection of keyhole limpet hemocyanin (KLH) at day four after the initial PQ treatment was used to induce a primary immune response; a second KLH challenge was performed at three months post the first KLH immunization to induce a secondary immune response. In steady state, treatment with 20 mg/kg PQ reduced the level of serum total IgG, but not that of IgM; treatment with 20 mg/kg PQ decreased the number of effector and memory lymphocytes, but not naïve or inactivated lymphocytes. During the primary immune response to KLH, treatment with 20 mg/kg PQ did not influence the proliferation of lymphocytes or expression of co-stimulatory molecules. Instead, treatment with 20 mg/kg PQ increased the apoptosis of lymphocytes at late stage, but not early stage of the primary immune response. During the secondary immune response to KLH, treatment with 20 mg/kg PQ reduced the serum anti-KLH IgG and KLH-responsive CD4 T cells and B cells. Moreover, effector or activated lymphocytes were more sensitive to PQ-induced apoptosis in vitro. Treatment with 2 mg/kg PQ did not impact memory immune response to KLH. Thus, treatment with 20 mg/kg PQ increased apoptosis of late stage effector cells to yield less memory cells and thereafter impair memory immune response, providing a novel understanding of the immunotoxicity of PQ.

scholarly journals Neuropathogenesis caused by Trypanosoma brucei, still an enigma to be unveiled

2021 ◽  
Vol 8 (4) ◽  
pp. 73-76
Author(s):  
Katherine Figarella
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Immune Responses ◽  
Trypanosoma Brucei ◽  
Late Stage ◽  
Early Stage ◽  
Tropical Diseases ◽  
The Central Nervous System ◽  
The Impact ◽  
The Brain

Trypanosoma brucei is one of the protozoa parasites that can enter the brain and cause injury associated with toxic effects of parasite-derived molecules or with immune responses against infection. Other protozoa parasites with brain tropism include Toxoplasma, Plasmodium, Amoeba, and, eventually, other Trypano-somatids such as T. cruzi and Leishmania. Together, these parasites affect billions of people worldwide and are responsible for more than 500.000 deaths annually. Factors determining brain tropism, mechanisms of in-vasion as well as processes ongoing inside the brain are not well understood. But, they depend on the par-asite involved. The pathogenesis caused by T. brucei initiates locally in the area of parasite inoculation, soon trypanosomes rich the blood, and the disease enters in the so-called early stage. The pathomecha-nisms in this phase have been described, even mole-cules used to combat the disease are effective during this period. Later, the disease evolves towards a late-stage, characterized by the presence of parasites in the central nervous system (CNS), the so-called meningo-encephalitic stage. This phase of the disease has not been sufficiently examined and remains a matter of investigation. Here, I stress the importance of delve into the study of the neuropathogenesis caused by T. brucei, which will enable the identification of path-ways that may be targeted to overcome parasites that reached the CNS. Finally, I highlight the impact that the application of tools developed in the last years in the field of neuroscience will have on the study of neglect-ed tropical diseases.

scholarly journals Adaptation to an amoeba host leads to Pseudomonas aeruginosa isolates with attenuated virulence

2022 ◽  
Author(s):  
Wai Leong ◽  
Wee Han Poh ◽  
Jonathan Williams ◽  
Carla Lutz ◽  
M. Mozammel Hoque ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Late Stage ◽  
Early Stage ◽  
Opportunistic Pathogen ◽  
Phenotypic Traits ◽  
Nucleotide Polymorphisms ◽  
Chronic Infections ◽  
The Impact

The opportunistic pathogen Pseudomonas aeruginosa , is ubiquitous in the environment, and in humans is capable of causing acute or chronic infections. In the natural environment, predation by bacterivorous protozoa represents a primary threat to bacteria. Here, we determined the impact of long-term exposure of P. aeruginosa to predation pressure. P. aeruginosa persisted when co-incubated with the bacterivorous Acanthamoeba castellanii for extended periods and produced genetic and phenotypic variants. Sequencing of late-stage amoeba-adapted P. aeruginosa isolates demonstrated single nucleotide polymorphisms within genes that encode known virulence factors and this correlated with a reduction in expression of virulence traits. Virulence towards the nematode, Caenorhabditis elegans , was attenuated in late-stage amoeba-adapted P. aeruginosa compared to early-stage amoeba-adapted and non-adapted counterparts. Further, late-stage amoeba-adapted P. aeruginosa showed increased competitive fitness and enhanced survival in amoeba as well as in macrophage and neutrophils. Interestingly, our findings indicate that the selection imposed by amoeba resulted in P. aeruginosa isolates with reduced virulence and enhanced fitness, similar to those recovered from chronic cystic fibrosis infections. Thus, predation by protozoa and long-term colonization of the human host may represent similar environments that select for similar losses of gene function. Importance Pseudomonas aeruginosa is an opportunistic pathogen that causes both acute infections in plants and animals, including humans, and chronic infections in immunocompromised and cystic fibrosis patients. This bacterium is commonly found in soils and water where bacteria are constantly under threat of being consumed by bacterial predators, e.g. protozoa. To escape being killed, bacteria have evolved a suite of mechanisms that protect them from being consumed or digested. Here, we examine the effect of long-term predation on the genotypes and phenotypes expressed by P. aeruginosa . We show that long term co-incubation with protozoa resulted in mutations that resulted in P. aeruginosa becoming less pathogenic. This is particularly interesting as we see similar mutations arise in bacteria associated with chronic infections. Importantly, the genetic and phenotypic traits possessed by late-stage amoeba-adapted P. aeruginosa are similar to what is observed for isolates obtained from chronic cystic fibrosis infections. This notable overlap in adaptation to different host types suggests similar selection pressures amongst host cell types as well as similar adaptation strategies.

Frequency of late-stage breast cancer diagnoses despite high mammography screening rates in an HMO

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. 1526-1526
Author(s):  
R. Haque ◽  
J. E. Schottinger ◽  
M. H. Kanter ◽  
C. C. Avila ◽  
R. Contreras ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Late Stage ◽  
Mammography Screening ◽  
Early Stage ◽  
Advanced Tumor Stage ◽  
Early Stage Disease ◽  
Advanced Tumor ◽  
Stage Disease ◽  
Late Stage Diagnosis ◽  
The Impact

1526 Background: Kaiser Permanente Southern California (KPSC) led the nation in screening women for breast cancer (BCa) with a mammography rate of nearly 90% in 2007 according to 2008 Healthcare Effectiveness Data and Information Set (HEDIS) measures. Despite successes in improving screening rates in this health plan that serves 3+ million diverse members, the percentage of women diagnosed with late stage BCa (stage III, IV) remained stable, varying from 12.9% (N∼323) in 2003 to 10.8% (N∼270) in 2007. To identify patient and health care factors associated with late stage diagnosis and the impact of its enhanced screening implementation guidelines, KPSC undertook this study. Methods: This cross-sectional study included a cohort of 10,580 BCa patients from 2003–2007. We compared women diagnosed with late stage disease versus those with early stage disease (stages I, II). P values (2-sided) were based on the chi-square distribution. Adjusted odds ratios and 95% confidence intervals were estimated using unconditional logistic regression. Results: Factors that were positively associated with late stage diagnosis in the univariate analyses included age, lack of recent mammography screening, worse tumor features, 80+ years of age, minority race, lower geocoded household income, increased healthcare visits, and use of Pap testing (P < 0.01 for all variables). Factors significantly associated with late stage diagnosis in the multivariate model included only lack of recent mammography screening (OR = 1.35, 95% CI: 1.14–1.58) and worse tumor features including high grade (grade 3, OR = 2.58, 95% CI: 1.96–3.40), positive lymph nodes (OR = 53.49, 95% CI: 39.90–71.72), and HER-2+ tumors (OR = 1.40, 95% CI: 1.13–1.72). Conclusions: Targeting older women, those with lower utilization, and women who did not have a recent mammogram may help further lower the prevalence of late stage diagnoses. However, given the extent of the health plan's previous efforts to enhance BCa screening rates, a ceiling effect may limit additional benefit. Additional efforts to decrease the rate of advanced tumor stage at diagnosis may include improving interpretation of mammograms or earlier detection of aggressive tumors by enhanced BRCA genetic testing. No significant financial relationships to disclose.

phlF− mutant of Pseudomonas fluorescens J2 improved 2,4-DAPG biosynthesis and biocontrol efficacy against tomato bacterial wilt

2014 ◽  
Vol 78 ◽  
pp. 1-8 ◽  
Author(s):  
Tian-Tian Zhou ◽  
Chun-Yu Li ◽  
Da Chen ◽  
Kai Wu ◽  
Qi-Rong Shen ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
Bacterial Wilt ◽  
Biocontrol Efficacy ◽  
Tomato Bacterial Wilt

scholarly journals Mutagenic strategies against luxS gene affect the early stage of biofilm formation of Campylobacter jejuni

2021 ◽  
Author(s):  
Martin Tereň ◽  
Ekaterina Shagieva ◽  
Lucie Vondrakova ◽  
Jitka Viktorova ◽  
Viviana Svarcova ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Biofilm Formation ◽  
Early Stage ◽  
Wild Type ◽  
Genetic Determinants ◽  
Autoinducer 2 ◽  
Naturally Occurring ◽  
Mutant Strains ◽  
The Impact

Abstract Currently, it is clear that the luxS gene has an impact on the process of biofilm formation in Campylobacter jejuni. However, even within the species naturally occurring strains of Campylobacter lacking the luxS gene exist, which can form biofilms. In order to better understand the genetic determinants and the role of quorum sensing through the LuxS/AI-2 pathway in biofilm formation, a set of mutant/complemented strains of C. jejuni 81–176 were prepared. Additionally, the impact of the mutagenic strategy used against the luxS gene was investigated. Biofilm formation was affected by both the presence and absence of the luxS gene, and by the mutagenic strategy used. Analysis by CLSM showed that all mutant strains formed significantly less biofilm mass when compared to the wild-type. Interestingly, the deletion mutant (∆luxS) showed a larger decrease in biofilm mass than the substitution (∙luxS) and insertional inactivated (⸬luxS) mutants, even though all the mutant strains lost the ability to produce autoinducer-2 molecules. Moreover, the biofilm of the ∆luxS mutant lacked the characteristic microcolonies observed in all other strains. The complementation of all mutant strains resulted in restored ability to produce AI-2, to form a complex biofilm, and to develop microcolonies at the level of the wild-type.

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