scholarly journals IS1 transposition is enhanced by translation errors and by bacterial growth at extreme glucose levels.

2006 ◽  
Vol 53 (4) ◽  
pp. 729-738 ◽  
Author(s):  
Arun S Kharat ◽  
Evelyne Coursange ◽  
Marjolaine Noirclerc-Savoye ◽  
Jérôme Lacoste ◽  
Michel Blot
Keyword(s):  
Inhibitory Concentration ◽  
Rare Event ◽  
Growth Conditions ◽  
Reporter System ◽  
Experimental Conditions ◽  
Transposition Frequency ◽  
Glucose Levels ◽  
Translation Accuracy ◽  
Translation Errors ◽  
Is1 Transposition

Transposition of insertion sequences (IS) is an enzyme-mediated process that only occurs in a minority of cells within a bacterial culture. Transposition is thus a rare event, but transposition frequency may vary depending on experimental conditions. For instance in a rich broth, IS elements are known to transpose during stationary phase but not during exponential growth. Using a reporter system which involves the activation of the cryptic bgl operon in Escherichia coli, we show that the frequency of IS1 transposition is a function of glucose concentration in the growth medium, it is increased by streptomycin amounts that are below minimum inhibitory concentration (sub-MIC) and is inhibited in an rpsL150 strain with high translation accuracy. Since starved cells are known to enhance ribosome frameshifting, our data suggests that growth conditions applied in this study could affect IS1 transposition by increasing translation infidelity.

scholarly journals Naturally Occurring Ecdysteroids in Triticum aestivum L. and Evaluation of Fenarimol as a Potential Inhibitor of Their Biosynthesis in Plants

2021 ◽  
Vol 22 (6) ◽  
pp. 2855
Author(s):  
Anna Janeczko ◽  
Jana Oklestkova ◽  
Danuše Tarkowská ◽  
Barbara Drygaś
Keyword(s):  
Triticum Aestivum ◽  
Winter Wheat ◽  
Triticum Aestivum L ◽  
Growth Conditions ◽  
Animal Kingdom ◽  
Experimental Conditions ◽  
P450 Monooxygenase ◽  
Naturally Occurring ◽  
Regulatory Effects ◽  
Potential Use

Ecdysteroids (ECs) are steroid hormones originally found in the animal kingdom where they function as insect molting hormones. Interestingly, a relatively high number of these substances can also be formed in plant cells. Moreover, ECs have certain regulatory effects on plant physiology, but their role in plants still requires further study. One of the main aims of the present study was to verify a hypothesis that fenarimol, an inhibitor of the biosynthesis of ECs in the animal kingdom, also affects the content of endogenous ECs in plants using winter wheat Triticum aestivum L. as a model plant. The levels of endogenous ECs in winter wheat, including the estimation of their changes during a course of different temperature treatments, have been determined using a sensitive analytical method based on UHPLC-MS/MS. Under our experimental conditions, four substances of EC character were detected in the tissue of interest in amounts ranging from less than 1 to over 200 pg·g−1 FW: 20-hydroxyecdysone, polypodine B, turkesterone, and isovitexirone. Among them, turkesterone was observed to be the most abundant EC and accumulated mainly in the crowns and leaves of wheat. Importantly, the level of ECs was observed to be dependent on the age of the plants, as well as on growth conditions (especially temperature). Fenarimol, an inhibitor of a cytochrome P450 monooxygenase, was shown to significantly decrease the level of naturally occurring ECs in experimental plants, which may indicate its potential use in studies related to the biosynthesis and physiological function of these substances in plants.

The Photoluminescence Spectra Research of SiC Thin Film under Different Sputtering Powers

2019 ◽  
Vol 295 ◽  
pp. 93-97
Author(s):  
Chang Zhao ◽  
Man Zhao ◽  
Su Ye Lv ◽  
Qing Jun Liu ◽  
Guang Jian Xing
Keyword(s):  
Thin Film ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Crystal Morphology ◽  
Growth Conditions ◽  
Photoluminescence Spectra ◽  
Experimental Conditions ◽  
Grain Sizes ◽  
Power Inputs ◽  
Scanning Electron

This study prepared an SiC thin film by using the ratio frequency magnetron sputtering method, investigated the effects of different sputtering powers on the SiC material and analysed the changes in crystal morphology and photoluminescence characteristics caused by changes in the growth conditions used. It was considered that there was 6H-SiC crystal morphologies in the SiC thin film under the experimental conditions prevailing in this study. The SiC morphologies with small grain sizes intermingled and therefore formed anSiC thin film. The analyses of the photoluminescence spectra and Scanning Electron Microscope indicated that the SiC thin film materials with preferable crystal compositions could be prepared under appropriate power inputs.

scholarly journals Characterization of LrgAB as a stationary phase-specific pyruvate uptake system in Streptococcus mutans

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Sang-Joon Ahn ◽  
Kamal Deep ◽  
Matthew E. Turner ◽  
Ivan Ishkov ◽  
Anthony Waters ◽  
...  
Keyword(s):  
Carbon Source ◽  
Stationary Phase ◽  
Streptococcus Mutans ◽  
Feedback Regulation ◽  
Growth Conditions ◽  
Stationary Growth Phase ◽  
Uptake System ◽  
Independent Manner ◽  
Negative Feedback Regulation ◽  
Glucose Levels

Abstract Background Our recent ‘-omics’ comparisons of Streptococcus mutans wild-type and lrgAB-mutant revealed that this organism undergoes dynamic cellular changes in the face of multiple exogenous stresses, consequently affecting its comprehensive virulence traits. In this current study, we further demonstrate that LrgAB functions as a S. mutans pyruvate uptake system. Results S. mutans excretes pyruvate during growth as an overflow metabolite, and appears to uptake this excreted pyruvate via LrgAB once the primary carbon source is exhausted. This utilization of excreted pyruvate was tightly regulated by glucose levels and stationary growth phase lrgAB induction. The degree of lrgAB induction was reduced by high extracellular levels of pyruvate, suggesting that lrgAB induction is subject to negative feedback regulation, likely through the LytST TCS, which is required for expression of lrgAB. Stationary phase lrgAB induction was efficiently inhibited by low concentrations of 3FP, a toxic pyruvate analogue, without affecting cell growth, suggesting that accumulated pyruvate is sensed either directly or indirectly by LytS, subsequently triggering lrgAB expression. S. mutans growth was inhibited by high concentrations of 3FP, implying that pyruvate uptake is necessary for S. mutans exponential phase growth and occurs in a Lrg-independent manner. Finally, we found that stationary phase lrgAB induction is modulated by hydrogen peroxide (H2O2) and by co-cultivation with H2O2-producing S. gordonii. Conclusions Pyruvate may provide S. mutans with an alternative carbon source under limited growth conditions, as well as serving as a buffer against exogenous oxidative stress. Given the hypothesized role of LrgAB in cell death and lysis, these data also provide an important basis for how these processes are functionally and mechanically connected to key metabolic pathways such as pyruvate metabolism.

scholarly journals Experience affects exercise-induced changes in catecholamines, glucose, and FFA

1989 ◽  
Vol 256 (1) ◽  
pp. R169-R173 ◽  
Author(s):  
A. J. Scheurink ◽  
A. B. Steffens ◽  
G. H. Dreteler ◽  
L. Benthem ◽  
R. Bruntink
Keyword(s):  
Metabolic Response ◽  
Plasma Catecholamines ◽  
Plasma Free Fatty Acid ◽  
Blood Component ◽  
Experimental Conditions ◽  
Glucose Levels ◽  
Exercise Induced ◽  
Induced Changes ◽  
Response To Exercise ◽  
First Time

The interference of the experimental conditions on the exercise-induced alterations in plasma catecholamines, plasma free fatty acids, and glucose and insulin concentrations was investigated in rats. Exercise consisted of strenuous swimming against a countercurrent (0.22 m/s) for 15 min in a pool with water of 33 degrees C. Before, during, and after swimming, blood samples were taken through a permanent heart catheter. The blood component levels in rats that were confronted with exercise for the very first time were compared with the levels in rats that were well accustomed to the exercise conditions. The very first time rats swam caused an enhanced release of epinephrine from the adrenal medulla and a reduced output of norepinephrine from the sympathetic nerve endings. Furthermore, in the first time swim group, blood glucose levels were higher and plasma free fatty acid concentrations were lower compared with the well-accustomed animals. There were no differences in plasma insulin concentrations. It is concluded that the experimental conditions may interfere considerably with the hormonal and metabolic response to exercise. Furthermore the results reinforce the idea that the two parts of the sympathoadrenal system are functionally and metabolically dissociated.

Identification and characterization of the regulatory elements of the inducible acetamidase operon from Mycobacterium smegmatis

2007 ◽  
Vol 53 (5) ◽  
pp. 599-606 ◽  
Author(s):  
Selvakumar Subbian ◽  
Sujatha Narayanan
Keyword(s):  
Mycobacterium Smegmatis ◽  
Regulatory Elements ◽  
Growth Conditions ◽  
Open Reading Frames ◽  
Reporter System ◽  
Mobility Shift ◽  
Crude Cell Lysate ◽  
Multiple Promoters ◽  
Promoter Probe ◽  
Mobility Shift Assay

The highly inducible acetamidase promoter from Mycobacterium smegmatis has been used as a tool in the study of mycobacterial genetics. The 4.2 kb acetamidase operon contains four putative open reading frames (ORFs) (amiC, amiA, amiD, and amiS) upstream of the 1.2 kb acetamidase ORF (amiE). In this article, using electrophoretic mobility shift assay and promoter probe analyses with a lacZ reporter system, we show the position of three putative operators within the acetamidase operon in M. smegmatis. Results from these studies reinforce previous findings about the involvement of multiple promoters in the regulation of acetamidase gene expression. Each of the identified operators are positioned upstream of the respective promoter reported in previous studies. We also found that the crude cell lysate of M. smegmatis containing potential regulators, obtained from bacteria grown under inducing or noninducing conditions, binds to specific operators. The binding affinity of each operator with its cognate regulator is significantly different from the other. This supports not only the previous model of acetamidase gene regulation in M. smegmatis but also explains the role of these operators in controlling the expression of respective promoters under different growth conditions.

BLOOD GLUCOSE LEVEL IN MICE.

1966 ◽  
Vol 52 (3) ◽  
pp. 357-367 ◽  
Author(s):  
Claus Rerup ◽  
Ingmar Lundquist
Keyword(s):  
Blood Glucose ◽  
Blood Glucose Level ◽  
Blood Sugar ◽  
Glucose Level ◽  
Enzymatic Reaction ◽  
Sampling Procedure ◽  
Experimental Conditions ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Blood Sugar Response

ABSTRACT Multiple serial blood glucose level determinations in individual mice were performed on small blood samples (10–25 μl) using the orbital bleeding technique. Glucose was determined specifically by a known enzymatic reaction. Blood glucose determined in this way was found a parameter of high reproducibility and precision, the latter being shown by the finding that differences between individual animals were highly significant in practically all the experiments. The standard deviation of the single measurement in normal mice was ± 8.2 mg/100 ml as determined from 600 samples, which indicated that the technique allows of the detection of blood sugar level changes of about 15 mg/100 ml or more with very high significance, in a group of 5 mice. In the sampling procedure as such, intravenous or subcutaneous saline injections did not necessarily have any effect on the blood glucose level, but interpretation of slight blood sugar changes under experimental conditions should always be based on a comparison with control groups, since the latter may sometimes show a slight but significant change. In normal non-fasting mice (NMRI strain) significant differences in homoeostatic blood glucose level adjustments were demonstrated. In acutely adrenalectomized mice blood glucose levels were lower and more variable than in normals. Alloxan injection (70 mg/kg) was followed in individual mice by a triphasic blood sugar response, as is known from other species.

PATTERNED GROWTH OF Si NANOWIRES: A COMPARATIVE STUDY OF VLS AND SLS

2010 ◽  
Vol 09 (03) ◽  
pp. 145-150 ◽  
Author(s):  
M. F. ZIA ◽  
J. ALI ◽  
A. NAWEED ◽  
A. S. BHATTI ◽  
S. NASEEM
Keyword(s):  
Silicon Nanowires ◽  
External Source ◽  
Growth Conditions ◽  
Si Nanowires ◽  
Experimental Conditions ◽  
Patterned Growth ◽  
Gaas Substrates ◽  
Different Temperatures ◽  
Ar Gas ◽  
Solid Liquid

In this paper, we report morphology of silicon nanowires ( Si - NWs ) grown on various surfaces and patterned substrates using Vapor–Liquid–Solid (VLS) and Solid–Liquid–Solid (SLS) techniques. It is observed that the growth conditions are critical in controlling the dimensions of wires in both techniques. In addition to this, it is also demonstrated that Si - NWs are essentially different grown on Si or GaAs substrates. For growth of Si - NWs by VLS, Si powder was evaporated in a tube furnace under Ar flow while substrates were kept at different temperatures. In SLS, experimental conditions were identical except that no external source was used. Si - NWs thus grown showed dependence on the flow rate of Ar gas and the temperature of the substrate. Interestingly, instead of only radial nannowires (NWs), nanobelts and tapered NWs were also grown on patterned Au -catalyzed GaAs surface. In the end, the analysis on the basis of existing theories of NW growth is presented. Optical properties of Si - NWs are also briefly discussed.

scholarly journals Influence of Acute High Glucose on Protein Abundance Changes in Murine Glomerular Mesangial Cells

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Michelle T. Barati ◽  
James C. Gould ◽  
Sarah A. Salyer ◽  
Susan Isaacs ◽  
Daniel W. Wilkey ◽  
...  
Keyword(s):  
Protein Expression ◽  
Posttranslational Modifications ◽  
High Glucose ◽  
Mesangial Cells ◽  
Expression Patterns ◽  
Growth Conditions ◽  
Glomerular Mesangial Cells ◽  
Two Dimensional Gel Electrophoresis ◽  
Glucose Levels ◽  
Flight Mass Spectrometry

The effects of acute exposure to high glucose levels as experienced by glomerular mesangial cells in postprandial conditions and states such as in prediabetes were investigated using proteomic methods. Two-dimensional gel electrophoresis and matrix assisted laser desorption ionization time of flight mass spectrometry methods were used to identify protein expression patterns in immortalized rat mesangial cells altered by 2 h high glucose (HG) growth conditions as compared to isoosmotic/normal glucose control (NG⁎) conditions. Unique protein expression changes at 2 h HG treatment were measured for 51 protein spots. These proteins could be broadly grouped into two categories: (1) proteins involved in cell survival/cell signaling and (2) proteins involved in stress response. Immunoblot experiments for a protein belonging to both categories, prohibitin (PHB), supported a trend for increased total expression as well as significant increases in an acidic PHB isoform. Additional studies confirmed the regulation of proteasomal subunit alpha-type 2 and the endoplasmic reticulum chaperone and oxidoreductase PDI (protein disulfide isomerase), suggesting altered ER protein folding capacity and proteasomal function in response to acute HG. We conclude that short term high glucose induces subtle changes in protein abundances suggesting posttranslational modifications and regulation of pathways involved in proteostasis.

scholarly journals Chromosomal Location Plays a Role in Regulation of Aflatoxin Gene Expression in Aspergillus parasiticus

2002 ◽  
Vol 68 (1) ◽  
pp. 306-315 ◽  
Author(s):  
Ching-Hsun Chiou ◽  
Michael Miller ◽  
David L. Wilson ◽  
Frances Trail ◽  
John E. Linz
Keyword(s):  
Gene Cluster ◽  
Promoter Activity ◽  
Aspergillus Parasiticus ◽  
Chromosomal Location ◽  
Selectable Marker ◽  
Growth Conditions ◽  
Gus Expression ◽  
Reporter System ◽  
Gus Reporter ◽  
Homologous Site

ABSTRACT The nor-1 gene in the filamentous fungus Aspergillus parasiticus encodes a ketoreductase involved in aflatoxin biosynthesis. To study environmental influences on nor-1 expression, we generated plasmid pAPGUSNNB containing a nor-1 promoter-β-glucuronidase (GUS) (encoded by uidA) reporter fusion with niaD (encodes nitrate reductase) as a selectable marker. niaD transformants of A. parasiticus strain NR-1 (niaD) carried pAPGUSNNB integrated predominantly at the nor-1 or niaD locus. Expression of the native nor-1 and nor-1::GUS reporter was compared in transformants grown under aflatoxin-inducing conditions by Northern and Western analyses and by qualitative and quantitative GUS activity assays. The timing and level of nor-1 promoter function with pAPGUSNNB integrated at nor-1 was similar to that observed for the native nor-1 gene. In contrast, nor-1 promoter activity in pAPGUSNNB and a second nor-1::GUS reporter construct, pBNG3.0, was not detectable when integration occurred at niaD. Because niaD-dependent regulation could account for the absence of expression at niaD, a third chromosomal location was analyzed using pAPGUSNP, which contained nor-1::GUS plus pyrG (encodes OMP decarboxylase) as a selectable marker. GUS expression was detectable only when pAPGUSNP integrated at nor-1 and was not detectable at pyrG, even under growth conditions that required pyrG expression. nor-1::GUS is regulated similarly to the native nor-1 gene when it is integrated at its homologous site within the aflatoxin gene cluster but is not expressed at native nor-1 levels at two locations outside of the aflatoxin gene cluster. We conclude that the GUS reporter system can be used effectively to measure nor-1 promoter activity and that nor-1 is subject to position-dependent regulation in the A. parasiticus chromosome.

scholarly journals Strain and Growth Conditions may Regulate Resistance of Listeria monocytogenes Biofilms to Benzalkonium Chloride

2020 ◽  
Vol 10 (3) ◽  
pp. 988 ◽  
Author(s):  
Lourenço Bonneville ◽  
Sagrario Ortiz ◽  
Vera Maia ◽  
Luisa Brito ◽  
Joaquín V. Martínez-Suárez
Keyword(s):  
Listeria Monocytogenes ◽  
Foodborne Pathogens ◽  
Benzalkonium Chloride ◽  
Culture Medium ◽  
Wild Type Strain ◽  
Inhibitory Concentration ◽  
Resistant Mutant ◽  
Growth Conditions ◽  
Processing Plants ◽  
Mutant Derivative

Listeria monocytogenes is one of the main foodborne pathogens. The formation of biofilms by L. monocytogenes contributes to its resistance to disinfectants, which represents a serious risk for food production plants. The aim of this study was to compare the effect of sub-inhibitory concentrations of benzalkonium chloride (BAC) (1.25 or 2.5 mg/L) on biofilm production and on biofilm reduction after exposure to an inhibitory concentration of BAC (1280 mg/L) in two isogenic L. monocytogenes strains: the BAC-sensitive wild-type strain S2-1 and its BAC-resistant mutant derivative S2BAC, which presented a multidrug resistance phenotype. The biofilm-forming ability of the strains under different BAC concentrations was evaluated by the resazurin method using polystyrene microplates. The biofilm reduction after BAC exposure was evaluated by using stainless steel coupons (SSCs). When the resazurin method was used, S2BAC produced significantly more biofilm in the presence of a sub-inhibitory concentration of BAC compared to that in the culture medium without BAC (p < 0.05). When the SSC method was used, the presence of sub-inhibitory concentrations of BAC resulted in a higher resistance of the biofilm for S2BAC compared to that in the culture medium without BAC (p < 0.05). This was not observed with the sensitive S2-1 strain. These results suggest that biofilm behavior depends on the strain and sub-inhibitory concentrations of disinfectants and may explain the ability of certain isolates to persist in niches of food processing plants.

Sign in / Sign up

Export Citation Format

Share Document