The Experts below are selected from a list of 11610 Experts worldwide ranked by ideXlab platform
Elizabeth M Boon - One of the best experts on this subject based on the ideXlab platform.
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Discovery of a Nitric Oxide Responsive Quorum Sensing Circuit in Vibrio cholerae
2018Co-Authors: Sajjad Hossain, Ilana Heckler, Elizabeth M BoonAbstract:Group behavior of the human pathogen Vibrio cholerae, including biofilm formation and virulence factor secretion, is mediated by a process known as quorum sensing. Quorum sensing is a way by which bacteria Coordinate Gene Expression in response to population density through the production, secretion, and detection of small molecules called autoinducers. Four autoinducer-mediated receptor histidine kinases have been implicated in quorum sensing through the phosphotransfer protein LuxU: CqsS, LuxP/Q, CqsR, and VpsS (Vc1445). Of these receptor kinases, VpsS is predicted to be cytosolic, and its cognate autoinducer is currently unknown. In this study, we demonstrate that the nitric oxide-bound complex of a member of the recently discovered family of nitric oxide-responsive hemoproteins called NosP (VcNosP is encoded by Vc1444; this Gene product is also known as VpsV) inhibits the autophosphorylation activity of VpsS and thus phosphate flow to LuxU. Therefore, we propose that VpsS contributes to the regulation of quorum sensing in a nitric-oxide-dependent manner through its interaction with NosP
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discovery of a nitric oxide responsive quorum sensing circuit in vibrio harveyi
ACS Chemical Biology, 2012Co-Authors: Bernadette M Henares, Kate E Higgins, Elizabeth M BoonAbstract:Group behavior of the human pathogen Vibrio cholerae, including biofilm formation and virulence factor secretion, is mediated by a process known as quorum sensing. Quorum sensing is a way by which bacteria Coordinate Gene Expression in response to population density through the production, secretion, and detection of small molecules called autoinducers. Four autoinducer-mediated receptor histidine kinases have been implicated in quorum sensing through the phosphotransfer protein LuxU: CqsS, LuxP/Q, CqsR, and VpsS (Vc1445). Of these receptor kinases, VpsS is predicted to be cytosolic, and its cognate autoinducer is currently unknown. In this study, we demonstrate that the nitric oxide-bound complex of a member of the recently discovered family of nitric oxide-responsive hemoproteins called NosP (VcNosP is encoded by Vc1444; this Gene product is also known as VpsV) inhibits the autophosphorylation activity of VpsS and thus phosphate flow to LuxU. Therefore, we propose that VpsS contributes to the regulation of quorum sensing in a nitric-oxide-dependent manner through its interaction with NosP.
Terry B Strom - One of the best experts on this subject based on the ideXlab platform.
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cytotoxic lymphocyte Gene Expression in peripheral blood leukocytes correlates with rejecting renal allografts
Transplantation, 1998Co-Authors: L Vasconcellos, Asher D Schachter, X X Zheng, L H Vasconcellos, Michael E Shapiro, William E Harmon, Terry B StromAbstract:BACKGROUND: We have shown previously that heightened Expression of the cytotoxic lymphocyte (CL) effector Genes perforin (P), granzyme B (GB), and Fas ligand (FasL), is closely correlated with acute allograft rejection, particularly when two or more target Genes are up-regulated. METHODS: We used quantitative reverse transcription-polymerase chain reaction to analyze CL Gene Expression from peripheral blood leukocytes (PBLs) and renal allograft biopsies in 31 paired samples of PBLs and renal tissue from 25 renal allograft recipients. Our aims were (1) to determine whether the Expression of CL Gene Expression in PBLs correlates with Expression of these Genes in renal allograft biopsy tissue and (2) to determine whether CL Gene Expression in PBLs correlates with the histological diagnosis. RESULTS: Coordinate Gene Expression in PBLs and acutely rejecting allografts was found in 9/11 (82%) for P, 07/11 (64%) for GB, and 10/11 (91%) for FasL. Coordinate absence was found in 15/20 (75%) for P, 17/20 (85%) for GB, and 16/20 (80%) for FasL in nonrejecting allografts. Furthermore, up-regulation of any two Genes in PBLs correlated with pathological diagnosis of rejection with excellent positive (100%) and negative (95%) predictive values. CONCLUSION: Coordinate CL Gene Expression in PBLs and the allograft is usually detected. CL Gene Expression in PBLs is closely associated with a pathologic diagnosis of rejection. CL Gene Expression in PBLs may serve as a noninvasive method of monitoring for renal allograft rejection.
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cytotoxic lymphocyte Gene Expression in peripheral blood leukocytes correlates with rejecting renal allografts
Transplantation, 1998Co-Authors: L Vasconcellos, Asher D Schachter, X X Zheng, L H Vasconcellos, Michael E Shapiro, William E Harmon, Terry B StromAbstract:Background. We have shown previously that heightened Expression of the cytotoxic lymphocyte (CL) effector Genes perforin (P), granzyme B (GB), and Fas ligand (FasL), is closely correlated with acute allograft rejection, particularly when two or more target Genes are up-regulated. Methods. We used quantitative reverse transcription-polymerase chain reaction to analyze CL Gene Expression from peripheral blood leukocytes (PBLs) and renal allograft biopsies in 31 paired samples of PBLs and renal tissue from 25 renal allograft recipients. Our aims were (1) to determine whether the Expression of CL Gene Expression in PBLs correlates with Expression of these Genes in renal allograft biopsy tissue and (2) to determine whether CL Gene Expression in PBLs correlates with the histological diagnosis. Results. Coordinate Gene Expression in PBLs and acutely rejecting allografts was found in 9/11 (82%) for P, 07/11 (64%) for GB, and 10/11 (91%) for FasL. Coordinate absence was found in 15/20 (75%) for P, 17/20 (85%) for GB, and 16/20 (80%) for FasL in nonrejecting allografts. Furthermore, up-regulation of any two Genes in PBLs correlated with pathological diagnosis of rejection with excellent positive (100%) and negative (95%) predictive values. Conclusion. Coordinate CL Gene Expression in PBLs and the allograft is usually detected. CL Gene Expression in PBLs is closely associated with a pathologic diagnosis of rejection. CL Gene Expression in PBLs may serve as a noninvasive method of monitoring for renal allograft rejection. Despite the growing array of immunosuppressive therapies available to transplant recipients, acute allograft rejection is a common event and is a major factor in determining both short-term and long-term outcomes for the transplant recipient (1). The occurrence of acute rejection is a significant risk factor for hastened development of chronic rejection (2), and therefore prompt diagnosis and treatment of acute rejection episodes is of utmost importance. Currently, acute renal allograft rejection is suspected only when the serum creatinine level rises, after the adverse effect of immunological and inflammatory processes on graft function. Surveillance allograft biopsies may prove to be beneficial in predicting rejection, but clinical application is limited by the invasive nature of this procedure. The early phases of T cell activation and the early immune activation events that precede fixed graft tissue injury can now be detected by quantitative reverse transcription-polymerase chain reaction (RT-PCR*) in preclinical models (3). Using human renal allograft biopsy specimens, we have shown previously that quantitative RT-PCR analysis of intragraft Gene Expression of the cytotoxic cell (CL) effector molecules perforin (P), granzyme B (GB), and Fas ligand (FasL) correlates with the pathological diagnosis with extraordinary sensitivity and specificity, particularly when any two of the three Genes are simultaneously up-regulated (4). In this study, we are testing the hypotheses that cytotoxic lymphocyte (CL) effector Genes are Coordinately expressed in peripheral blood leukocytes (PBLs) and renal allografts and CL effector molecule Gene Expression in PBLs correlates with the histological diagnosis.
Luis A. Sayavedra-soto - One of the best experts on this subject based on the ideXlab platform.
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Quorum Quenching of Nitrobacter winogradskyi Suggests that Quorum Sensing Regulates Fluxes of Nitrogen Oxide(s) during Nitrification
mBio, 2016Co-Authors: Brett L. Mellbye, Andrew T. Giguere, Peter J. Bottomley, Luis A. Sayavedra-sotoAbstract:ABSTRACT Quorum sensing (QS) is a widespread process in bacteria used to Coordinate Gene Expression with cell density, diffusion dynamics, and spatial distribution through the production of diffusible chemical signals. To date, most studies on QS have focused on model bacteria that are amenable to Genetic manipulation and capable of high growth rates, but many environmentally important bacteria have been overlooked. For example, representatives of proteobacteria that participate in nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, produce QS signals called acyl-homoserine lactones (AHLs). Nitrification emits nitrogen oxide gases (NO, NO 2 , and N 2 O), which are potentially hazardous compounds that contribute to global warming. Despite considerable interest in nitrification, the purpose of QS in the physiology/ecology of nitrifying bacteria is poorly understood. Through a quorum quenching approach, we investigated the role of QS in a well-studied AHL-producing nitrite oxidizer, Nitrobacter winogradskyi. We added a recombinant AiiA lactonase to N. winogradskyi cultures to degrade AHLs to prevent their accumulation and to induce a QS-negative phenotype and then used mRNA sequencing (mRNA-Seq) to identify putative QS-controlled Genes. Our transcriptome analysis showed that Expression of nirK and nirK cluster Genes ( ncgABC ) increased up to 19.9-fold under QS-proficient conditions (minus active lactonase). These data led to us to query if QS influenced nitrogen oxide gas fluxes in N. winogradskyi . Production and consumption of NO x increased and production of N 2 O decreased under QS-proficient conditions. Quorum quenching transcriptome approaches have broad potential to identify QS-controlled Genes and phenotypes in organisms that are not Genetically tractable. IMPORTANCE Bacterial cell-cell signaling, or quorum sensing (QS), is a method of bacterial communication and Gene regulation that is well studied in bacteria. However, little is known about the purpose of QS in many environmentally important bacteria. Here, we demonstrate quorum quenching coupled with mRNA-Seq to identify QS-controlled Genes and phenotypes in Nitrobacter winogradskyi, a nitrite-oxidizing bacterium. Nitrite oxidizers play an important role in the nitrogen cycle though their participation in nitrification, the aerobic oxidation of ammonia to nitrate via nitrite. Our quorum quenching approach revealed that QS influences production and consumption of environmentally important nitrogen oxide gases (NO, NO 2 , and N 2 O) in N. winogradskyi . This study demonstrated a novel technique for studying QS in difficult-to-work-with microorganisms and showed that nitrite oxidizers might also contribute to nitrification-dependent production of nitrogen oxide gases that contribute to global warming.
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Quorum Quenching of Nitrobacter winogradskyi Suggests that Quorum Sensing Regulates Fluxes of Nitrogen Oxide(s) during Nitrification
American Society for Microbiology, 2016Co-Authors: Brett L. Mellbye, Andrew T. Giguere, Peter J. Bottomley, Luis A. Sayavedra-sotoAbstract:Quorum sensing (QS) is a widespread process in bacteria used to Coordinate Gene Expression with cell density, diffusion dynamics, and spatial distribution through the production of diffusible chemical signals. To date, most studies on QS have focused on model bacteria that are amenable to Genetic manipulation and capable of high growth rates, but many environmentally important bacteria have been overlooked. For example, representatives of proteobacteria that participate in nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, produce QS signals called acyl-homoserine lactones (AHLs). Nitrification emits nitrogen oxide gases (NO, NO2, and N2O), which are potentially hazardous compounds that contribute to global warming. Despite considerable interest in nitrification, the purpose of QS in the physiology/ecology of nitrifying bacteria is poorly understood. Through a quorum quenching approach, we investigated the role of QS in a well-studied AHL-producing nitrite oxidizer, Nitrobacter winogradskyi. We added a recombinant AiiA lactonase to N. winogradskyi cultures to degrade AHLs to prevent their accumulation and to induce a QS-negative phenotype and then used mRNA sequencing (mRNA-Seq) to identify putative QS-controlled Genes. Our transcriptome analysis showed that Expression of nirK and nirK cluster Genes (ncgABC) increased up to 19.9-fold under QS-proficient conditions (minus active lactonase). These data led to us to query if QS influenced nitrogen oxide gas fluxes in N. winogradskyi. Production and consumption of NOx increased and production of N2O decreased under QS-proficient conditions. Quorum quenching transcriptome approaches have broad potential to identify QS-controlled Genes and phenotypes in organisms that are not Genetically tractable
L Vasconcellos - One of the best experts on this subject based on the ideXlab platform.
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cytotoxic lymphocyte Gene Expression in peripheral blood leukocytes correlates with rejecting renal allografts
Transplantation, 1998Co-Authors: L Vasconcellos, Asher D Schachter, X X Zheng, L H Vasconcellos, Michael E Shapiro, William E Harmon, Terry B StromAbstract:BACKGROUND: We have shown previously that heightened Expression of the cytotoxic lymphocyte (CL) effector Genes perforin (P), granzyme B (GB), and Fas ligand (FasL), is closely correlated with acute allograft rejection, particularly when two or more target Genes are up-regulated. METHODS: We used quantitative reverse transcription-polymerase chain reaction to analyze CL Gene Expression from peripheral blood leukocytes (PBLs) and renal allograft biopsies in 31 paired samples of PBLs and renal tissue from 25 renal allograft recipients. Our aims were (1) to determine whether the Expression of CL Gene Expression in PBLs correlates with Expression of these Genes in renal allograft biopsy tissue and (2) to determine whether CL Gene Expression in PBLs correlates with the histological diagnosis. RESULTS: Coordinate Gene Expression in PBLs and acutely rejecting allografts was found in 9/11 (82%) for P, 07/11 (64%) for GB, and 10/11 (91%) for FasL. Coordinate absence was found in 15/20 (75%) for P, 17/20 (85%) for GB, and 16/20 (80%) for FasL in nonrejecting allografts. Furthermore, up-regulation of any two Genes in PBLs correlated with pathological diagnosis of rejection with excellent positive (100%) and negative (95%) predictive values. CONCLUSION: Coordinate CL Gene Expression in PBLs and the allograft is usually detected. CL Gene Expression in PBLs is closely associated with a pathologic diagnosis of rejection. CL Gene Expression in PBLs may serve as a noninvasive method of monitoring for renal allograft rejection.
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cytotoxic lymphocyte Gene Expression in peripheral blood leukocytes correlates with rejecting renal allografts
Transplantation, 1998Co-Authors: L Vasconcellos, Asher D Schachter, X X Zheng, L H Vasconcellos, Michael E Shapiro, William E Harmon, Terry B StromAbstract:Background. We have shown previously that heightened Expression of the cytotoxic lymphocyte (CL) effector Genes perforin (P), granzyme B (GB), and Fas ligand (FasL), is closely correlated with acute allograft rejection, particularly when two or more target Genes are up-regulated. Methods. We used quantitative reverse transcription-polymerase chain reaction to analyze CL Gene Expression from peripheral blood leukocytes (PBLs) and renal allograft biopsies in 31 paired samples of PBLs and renal tissue from 25 renal allograft recipients. Our aims were (1) to determine whether the Expression of CL Gene Expression in PBLs correlates with Expression of these Genes in renal allograft biopsy tissue and (2) to determine whether CL Gene Expression in PBLs correlates with the histological diagnosis. Results. Coordinate Gene Expression in PBLs and acutely rejecting allografts was found in 9/11 (82%) for P, 07/11 (64%) for GB, and 10/11 (91%) for FasL. Coordinate absence was found in 15/20 (75%) for P, 17/20 (85%) for GB, and 16/20 (80%) for FasL in nonrejecting allografts. Furthermore, up-regulation of any two Genes in PBLs correlated with pathological diagnosis of rejection with excellent positive (100%) and negative (95%) predictive values. Conclusion. Coordinate CL Gene Expression in PBLs and the allograft is usually detected. CL Gene Expression in PBLs is closely associated with a pathologic diagnosis of rejection. CL Gene Expression in PBLs may serve as a noninvasive method of monitoring for renal allograft rejection. Despite the growing array of immunosuppressive therapies available to transplant recipients, acute allograft rejection is a common event and is a major factor in determining both short-term and long-term outcomes for the transplant recipient (1). The occurrence of acute rejection is a significant risk factor for hastened development of chronic rejection (2), and therefore prompt diagnosis and treatment of acute rejection episodes is of utmost importance. Currently, acute renal allograft rejection is suspected only when the serum creatinine level rises, after the adverse effect of immunological and inflammatory processes on graft function. Surveillance allograft biopsies may prove to be beneficial in predicting rejection, but clinical application is limited by the invasive nature of this procedure. The early phases of T cell activation and the early immune activation events that precede fixed graft tissue injury can now be detected by quantitative reverse transcription-polymerase chain reaction (RT-PCR*) in preclinical models (3). Using human renal allograft biopsy specimens, we have shown previously that quantitative RT-PCR analysis of intragraft Gene Expression of the cytotoxic cell (CL) effector molecules perforin (P), granzyme B (GB), and Fas ligand (FasL) correlates with the pathological diagnosis with extraordinary sensitivity and specificity, particularly when any two of the three Genes are simultaneously up-regulated (4). In this study, we are testing the hypotheses that cytotoxic lymphocyte (CL) effector Genes are Coordinately expressed in peripheral blood leukocytes (PBLs) and renal allografts and CL effector molecule Gene Expression in PBLs correlates with the histological diagnosis.
Bernadette M Henares - One of the best experts on this subject based on the ideXlab platform.
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discovery of a nitric oxide responsive quorum sensing circuit in vibrio harveyi
ACS Chemical Biology, 2012Co-Authors: Bernadette M Henares, Kate E Higgins, Elizabeth M BoonAbstract:Group behavior of the human pathogen Vibrio cholerae, including biofilm formation and virulence factor secretion, is mediated by a process known as quorum sensing. Quorum sensing is a way by which bacteria Coordinate Gene Expression in response to population density through the production, secretion, and detection of small molecules called autoinducers. Four autoinducer-mediated receptor histidine kinases have been implicated in quorum sensing through the phosphotransfer protein LuxU: CqsS, LuxP/Q, CqsR, and VpsS (Vc1445). Of these receptor kinases, VpsS is predicted to be cytosolic, and its cognate autoinducer is currently unknown. In this study, we demonstrate that the nitric oxide-bound complex of a member of the recently discovered family of nitric oxide-responsive hemoproteins called NosP (VcNosP is encoded by Vc1444; this Gene product is also known as VpsV) inhibits the autophosphorylation activity of VpsS and thus phosphate flow to LuxU. Therefore, we propose that VpsS contributes to the regulation of quorum sensing in a nitric-oxide-dependent manner through its interaction with NosP.