scholarly journals Symbiotic Induction of Pyruvate Dehydrogenase Genes from Sinorhizobium meliloti

2000 ◽  
Vol 13 (5) ◽  
pp. 483-493 ◽  
Author(s):  
Didier Cabanes ◽  
Pierre Boistard ◽  
Jacques Batut
Keyword(s):  
Gene Expression ◽  
Pyruvate Dehydrogenase ◽  
Sinorhizobium Meliloti ◽  
Living Conditions ◽  
Free Living ◽  
Gene Encoding ◽  
Gram Positive Bacteria ◽  
Regulatory Cascade ◽  
Lipoamide Dehydrogenase ◽  
Free Living Conditions

Genes coding for components of the pyruvate dehydrogenase (PDH) multienzyme complex (PDHc) from Sinorhizobium meliloti, the alfalfa symbiont, have been isolated on the basis of their high expression in symbiotic bacteria. The E1p component, PDH, is encoded by two genes, pdhAα (1,047 bp) and pdhAβ (1,383 bp), a situation encountered in the α-proteobacteria Rickettsia prowazekii and Zymomonas mobilis as well as in some Gram-positive bacteria and in mitochondria. pdhAα and pdhAβ precede pdhB (1,344 bp), which encodes the E2p component, dihy-drolipoamide acetyltransferase, of the PDHc. No gene encoding the E3 component, lipoamide dehydrogenase, was found in the immediate vicinity of pdhA and pdhB genes. pdhAα, pdhAβ, and pdhB likely constitute an operon. Here, we provide evidence that pdhA expression is induced in the symbiotic stage, compared with free-living conditions. We demonstrate that symbiotic expression of pdhA genes does not depend on the fixLJ regulatory cascade that regulates nitrogen fixation and respiration gene expression in symbiotic S. meliloti cells. Induction of pdhA expression could be obtained under free-living conditions upon the addition of pyruvate to the culture medium. Induction by pyruvate and symbiotic activation of pdh gene expression take place at the same promoter.

scholarly journals HPrK Regulates Succinate-Mediated Catabolite Repression in the Gram-Negative Symbiont Sinorhizobium meliloti

2008 ◽  
Vol 191 (1) ◽  
pp. 298-309 ◽  
Author(s):  
Catalina Arango Pinedo ◽  
Daniel J. Gage
Keyword(s):  
Catabolite Repression ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Phosphotransferase System ◽  
Free Living ◽  
Gene Encoding ◽  
Common Component ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Living Organisms

ABSTRACT The HPrK kinase/phosphatase is a common component of the phosphotransferase system (PTS) of gram-positive bacteria and regulates catabolite repression through phosphorylation/dephosphorylation of its substrate, the PTS protein HPr, at a conserved serine residue. Phosphorylation of HPr by HPrK also affects additional phosphorylation of HPr by the PTS enzyme EI at a conserved histidine residue. Sinorhizobium meliloti can live as symbionts inside legume root nodules or as free-living organisms and is one of the relatively rare gram-negative bacteria known to have a gene encoding HPrK. We have constructed S. meliloti mutants that lack HPrK or that lack key amino acids in HPr that are likely phosphorylated by HPrK and EI. Deletion of hprK in S. meliloti enhanced catabolite repression caused by succinate, as did an S53A substitution in HPr. Introduction of an H22A substitution into HPr alleviated the strong catabolite repression phenotypes of strains carrying ΔhprK or hpr(S53A) mutations, demonstrating that HPr-His22-P is needed for strong catabolite repression. Furthermore, strains with a hpr(H22A) allele exhibited relaxed catabolite repression. These results suggest that HPrK phosphorylates HPr at the serine-53 residue, that HPr-Ser53-P inhibits phosphorylation at the histidine-22 residue, and that HPr-His22-P enhances catabolite repression in the presence of succinate. Additional experiments show that ΔhprK mutants overproduce exopolysaccharides and form nodules that do not fix nitrogen.

scholarly journals Sinorhizobium meliloti SyrA Mediates the Transcriptional Regulation of Genes Involved in Lipopolysaccharide Sulfation and Exopolysaccharide Biosynthesis

2007 ◽  
Vol 189 (6) ◽  
pp. 2510-2520 ◽  
Author(s):  
David H. Keating
Keyword(s):  
Sinorhizobium Meliloti ◽  
Response Regulator ◽  
Living Conditions ◽  
Wild Type ◽  
Two Component System ◽  
Free Living ◽  
Component System ◽  
Two Component ◽  
Exopolysaccharide Biosynthesis ◽  
Free Living Conditions

ABSTRACT Sinorhizobium meliloti is a gram-negative soil bacterium found either in free-living form or as a nitrogen-fixing endosymbiont of leguminous plants such as Medicago sativa (alfalfa). S. meliloti synthesizes an unusual sulfate-modified form of lipopolysaccharide (LPS). A recent study reported the identification of a gene, lpsS, which encodes an LPS sulfotransferase activity in S. meliloti. Mutants bearing a disrupted version of lpsS exhibit an altered symbiosis, in that they elicit more nodules than wild type. However, under free-living conditions, the lpsS mutant displayed no change in LPS sulfation. These data suggest that the expression of lpsS is differentially regulated, such that it is transcriptionally repressed during free-living conditions but upregulated during symbiosis. Here, I show that the expression of lpsS is upregulated in strains that constitutively express the symbiotic regulator SyrA. SyrA is a small protein that lacks an apparent DNA binding domain and is predicted to be located in the cytoplasmic membrane yet is sufficient to upregulate lpsS transcription. Furthermore, SyrA can mediate the transcriptional upregulation of exo genes involved in the biosynthesis of the symbiotic exopolysaccharide succinoglycan. The SyrA-mediated transcriptional upregulation of lpsS and exo transcription is blocked in mutants harboring a mutation in chvI, which encodes the response regulator of a conserved two-component system. Thus, SyrA likely acts indirectly to promote transcriptional upregulation of lpsS and exo genes through a mechanism that requires the ExoS/ChvI two-component system.

Safety and Performance of the Omnipod®Hybrid Closed-Loop System in Adolescents with Type 1 Diabetes over Five Days Under Free-Living Conditions

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 1376-P
Author(s):  
GREGORY P. FORLENZA ◽  
BRUCE BUCKINGHAM ◽  
JENNIFER SHERR ◽  
THOMAS A. PEYSER ◽  
JOON BOK LEE ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Closed Loop ◽  
Living Conditions ◽  
Loop System ◽  
Closed Loop System ◽  
Free Living ◽  
And Performance ◽  
Free Living Conditions

Safety and Performance of the Omnipod® Hybrid Closed-Loop System in Adults with Type 1 Diabetes over Five Days Under Free-Living Conditions

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 207-OR
Author(s):  
BRUCE A. BUCKINGHAM ◽  
JENNIFER SHERR ◽  
GREGORY P. FORLENZA ◽  
THOMAS A. PEYSER ◽  
JOON BOK LEE ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Closed Loop ◽  
Living Conditions ◽  
Loop System ◽  
Closed Loop System ◽  
Free Living ◽  
And Performance ◽  
Free Living Conditions

scholarly journals Data-driven modelling approach to circadian temperature rhythm profiles in free-living conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jari Lipsanen ◽  
Liisa Kuula ◽  
Marko Elovainio ◽  
Timo Partonen ◽  
Anu-Katriina Pesonen
Keyword(s):  
Skin Surface ◽  
Living Conditions ◽  
Data Driven ◽  
Physiological Data ◽  
Free Living ◽  
Physiological Level ◽  
Temperature Rhythm ◽  
Time Series Modelling ◽  
Circadian Preference ◽  
Free Living Conditions

AbstractThe individual variation in the circadian rhythms at the physiological level is not well understood. Albeit self-reported circadian preference profiles have been consolidated, their premises are grounded on human experience, not on physiology. We used data-driven, unsupervised time series modelling to characterize distinct profiles of the circadian rhythm measured from skin surface temperature in free-living conditions. We demonstrate the existence of three distinct clusters of individuals which differed in their circadian temperature profiles. The cluster with the highest temperature amplitude and the lowest midline estimating statistic of rhythm, or rhythm-adjusted mean, had the most regular and early-timed sleep–wake rhythm, and was the least probable for those with a concurrent delayed sleep phase, or eveningness chronotype. While the clusters associated with the observed sleep and circadian preference patterns, the entirely unsupervised modelling of physiological data provides a novel basis for modelling and understanding the human circadian functions in free-living conditions.

Invariance of Wearing Location of Omron-BI Pedometers: A Validation Study

2010 ◽  
Vol 7 (6) ◽  
pp. 706-717 ◽  
Author(s):  
Weimo Zhu ◽  
Miyoung Lee
Keyword(s):  
Validation Study ◽  
Absolute Error ◽  
Activity Monitor ◽  
Error Rates ◽  
Living Conditions ◽  
The Body ◽  
Validity And Reliability ◽  
Free Living ◽  
Climbing Stairs ◽  
Free Living Conditions

Background:The purpose of this study was to investigate the validity and reliability evidences of the Omron BI pedometer, which could count steps taken even when worn at different locations on the body.Methods:Forty (20 males and 20 females) adults were recruited to walk wearing 5 sets, 1 set at a time, of 10 BI pedometers during testing, 1 each at 10 different locations. For comparison, they also wore 2 Yamax Digi-Walker SW-200 pedometers and a Dynastream AMP 331 activity monitor. The subjects walked in 3 free-living conditions: a fat sidewalk, stairs, and mixed conditions.Results:Except for a slight decrease in accuracy in the pant pocket locations, Omron BI pedometers counted steps accurately across other locations when subjects walked on the fat sidewalk, and the performance was consistent across devices and trials. When the subjects climbed up stairs, however, the absolute error % of the pant pocket locations increased significantly (P < .05) and similar or higher error rates were found in the AMP 331 and SW-200s.Conclusions:The Omron BI pedometer can accurately count steps when worn at various locations on the body in free-living conditions except for front pant pocket locations, especially when climbing stairs.

scholarly journals Substantial Intra-Individual Variability in Post-Prandial Time to Peak in Controlled and Free-Living Conditions in Children with Type 1 Diabetes

Nutrients ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 4154
Author(s):  
Emily Bell ◽  
Sabrina Binkowski ◽  
Elaine Sanderson ◽  
Barbara Keating ◽  
Grant Smith ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Individual Variability ◽  
Living Conditions ◽  
Optimal Time ◽  
Daily Routine ◽  
Free Living ◽  
Continuous Glucose Monitor ◽  
Time To Peak ◽  
Free Living Conditions

The optimal time to bolus insulin for meals is challenging for children and adolescents with type 1 diabetes (T1D). Current guidelines to control glucose excursions do not account for individual differences in glycaemic responses to meals. This study aimed to examine the within- and between-person variability in time to peak (TTP) glycaemic responses after consuming meals under controlled and free-living conditions. Participants aged 8–15 years with T1D ≥ 1 year and using a continuous glucose monitor (CGM) were recruited. Participants consumed a standardised breakfast for six controlled days and maintained their usual daily routine for 14 free-living days. CGM traces were collected after eating. Linear mixed models were used to identify within- and between-person variability in the TTP after each of the controlled breakfasts, free-living breakfasts (FLB), and free-living dinners (FLD) conditions. Thirty participants completed the study (16 females; mean age and standard deviation (SD) 10.5 (1.9)). The TTP variability was greater within a person than the variability between people for all three meal types (between-person vs within-person SD; controlled breakfast 18.5 vs 38.9 minutes; FLB 14.1 vs 49.6 minutes; FLD 5.7 vs 64.5 minutes). For the first time, the study showed that within-person variability in TTP glycaemic responses is even greater than between-person variability.

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