scholarly journals Global gene expression in Escherichia coli K-12 during short-term and long-term adaptation to glucose-limited continuous culture conditions

Microbiology ◽  
2006 ◽  
Vol 152 (7) ◽  
pp. 2111-2127 ◽  
Author(s):  
Alessandro G. Franchini ◽  
Thomas Egli
Keyword(s):  
Escherichia Coli ◽  
Continuous Culture ◽  
Transcriptome Analysis ◽  
Glyoxylate Cycle ◽  
Carbon Sources ◽  
Culture Conditions ◽  
Mrna Levels ◽  
Short Term ◽  
K 12

Microarray technology was used to study the cellular events that take place at the transcription level during short-term (physiological) and long-term (genetic) adaptation of the faecal indicator bacterium Escherichia coli K-12 to slow growth under limited nutrient supply. Short-term and long-term adaptation were assessed by comparing the mRNA levels isolated after 40 or 500 h of glucose-limited continuous culture at a dilution rate of 0.3 h−1 with those from batch culture with glucose excess. A large number of genes encoding periplasmic binding proteins were upregulated, indicating that the cells are prepared for high-affinity uptake of all types of carbon sources during glucose-limited growth in continuous culture. All the genes belonging to the maltose (mal/lamB) and galactose (mgl/gal) operons were upregulated. A similar transcription pattern was observed for long-term cultures except that the expression factors were lower than in the short-term adaptation. The patterns of upregulation were confirmed by real-time RT-PCR. A switch from a fully operational citric acid cycle to the PEP-glyoxylate cycle was clearly observed in cells grown in glucose-limited continuous culture when compared to batch-grown cells and this was confirmed by transcriptome analysis. This transcriptome analysis confirms and extends the observations from previous proteome and catabolome studies in the authors' laboratory.

scholarly journals Transcriptional Responses of Escherichia coli K-12 and O157:H7 Associated with Lettuce Leaves

2012 ◽  
Vol 78 (6) ◽  
pp. 1752-1764 ◽  
Author(s):  
Ryan C. Fink ◽  
Elaine P. Black ◽  
Zhe Hou ◽  
Masayuki Sugawara ◽  
Michael J. Sadowsky ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Leaf Surface ◽  
Short Term ◽  
Transcriptional Responses ◽  
Content Type ◽  
E Coli ◽  
Leaf Surfaces ◽  
K 12

ABSTRACTAn increasing number of outbreaks of gastroenteritis recently caused byEscherichia coliO157:H7 have been linked to the consumption of leafy green vegetables. Although it is known thatE. colisurvives and grows in the phyllosphere of lettuce plants, the molecular mechanisms by which this bacterium associates with plants are largely unknown. The goal of this study was to identifyE. coligenes relevant to its interaction, survival, or attachment to lettuce leaf surfaces, comparingE. coliK-12, a model system, andE. coliO157:H7, a pathogen associated with a large number of outbreaks. Using microarrays, we found that upon interaction with intact leaves, 10.1% and 8.7% of the 3,798 shared genes were differentially expressed in K-12 and O157:H7, respectively, whereas 3.1% changed transcript levels in both. The largest group of genes downregulated consisted of those involved in energy metabolism, includingtnaA(33-fold change), encoding a tryptophanase that converts tryptophan into indole. Genes involved in biofilm modulation (bhsAandybiM) and curli production (csgAandcsgB) were significantly upregulated inE. coliK-12 and O157:H7. BothcsgAandbhsA(ycfR) mutants were impaired in the long-term colonization of the leaf surface, but onlycsgAmutants had diminished ability in short-term attachment experiments. Our data suggested that the interaction ofE. coliK-12 and O157:H7 with undamaged lettuce leaves likely is initiated via attachment to the leaf surface using curli fibers, a downward shift in their metabolism, and the suppression of biofilm formation.

scholarly journals A study of the genotoxic potential of flavonoids using short-term bacterial assays.

1993 ◽  
Vol 40 (4) ◽  
pp. 549-554 ◽  
Author(s):  
H Czeczot ◽  
J Kusztelak
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Mutagenic Effect ◽  
Short Term ◽  
Sos System ◽  
Genotoxic Potential ◽  
Sos Chromotest ◽  
Activation System ◽  
K 12 ◽  
Alkylate Dna

Genotoxic activities of flavonoids (quercetin, rhamnetin, isorhamnetin, apigenin, luteolin) were investigated using two short-term bacterial assays. In the "repair test" in Salmonella typhimurium (strains TA1538 uvrB- and TA1978 uvrB+) the flavonoids studied did not introduce any damage into the DNA recognized by UvrABC nuclease (correndonuclease II). The results of the SOS-Chromotest in Escherichia coli K-12 strains PQ37 (tag+, alk+) and PQ243 (tagA, alkA) indicated that flavonoids only weakly induced the SOS system. The addition of a liver activation system (S9 mix) did not increase the mutagenic effect of the flavonoids tested. Two compounds: rhamnetin, isorhamnetin and their putative metabolites formed in the presence of the S9 mix did not alkylate DNA at N-3 of adenine.

scholarly journals Convergent Pathways for Utilization of the Amino Sugars N-Acetylglucosamine,N-Acetylmannosamine, and N-Acetylneuraminic Acid by Escherichia coli

1999 ◽  
Vol 181 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Jacqueline Plumbridge ◽  
Eric Vimr
Keyword(s):  
Escherichia Coli ◽  
Carbon Sources ◽  
Amino Sugars ◽  
Good Growth ◽  
Gene Products ◽  
Phosphotransferase System ◽  
Regulatory Mutation ◽  
Putative Gene ◽  
Acetylneuraminic Acid ◽  
K 12

ABSTRACT N-Acetylglucosamine (GlcNAc) andN-acetylneuraminic acid (NANA) are good carbon sources forEscherichia coli K-12, whereasN-acetylmannosamine (ManNAc) is metabolized very slowly. The isolation of regulatory mutations which enhanced utilization of ManNAc allowed us to elucidate the pathway of its degradation. ManNAc is transported by the manXYZ-encoded phosphoenolpyruvate-dependent phosphotransferase system (PTS) transporter producing intracellular ManNAc-6-P. This phosphorylated hexosamine is subsequently converted to GlcNAc-6-P, which is further metabolized by the nagBA-encoded deacetylase and deaminase of the GlcNAc-6-P degradation pathway. Two independent mutations are necessary for good growth on ManNAc. One mutation maps tomlc, and mutations in this gene are known to enhance the expression of manXYZ. The second regulatory mutation was mapped to the nanAT operon, which encodes the NANA transporter and NANA lyase. The combined action of thenanAT gene products converts extracellular NANA to intracellular ManNAc. The second regulatory mutation defines an open reading frame (ORF), called yhcK, as the gene for the repressor of the nan operon (nanR). Mutations in the repressor enhance expression of the nanAT genes and, presumably, three distal, previously unidentified genes,yhcJIH. Expression of just one of these downstream ORFs,yhcJ, is necessary for growth on ManNAc in the presence of an mlc mutation. The yhcJ gene appears to encode a ManNAc-6-P-to-GlcNAc-6-P epimerase (nanE). Another putative gene in the nan operon, yhcI, likely encodes ManNAc kinase (nanK), which should phosphorylate the ManNAc liberated from NANA by the NanA protein. Use of NANA as carbon source by E. coli also requires thenagBA gene products. The existence of a ManNAc kinase and epimerase within the nan operon allows us to propose that the pathways for dissimilation of the three amino sugars GlcNAc, ManNAc, and NANA, all converge at the step of GlcNAc-6-P.

scholarly journals Regulation of P-Fimbrial Phase Variation Frequencies in Escherichia coli CFT073

2007 ◽  
Vol 75 (7) ◽  
pp. 3325-3334 ◽  
Author(s):  
Nicola Holden ◽  
Makrina Totsika ◽  
Lynn Dixon ◽  
Kirsteen Catherwood ◽  
David L. Gally
Keyword(s):  
Escherichia Coli ◽  
Phase Transition ◽  
Regulatory Region ◽  
Phase Variation ◽  
Culture Conditions ◽  
Host Tissue ◽  
Clinical Isolates ◽  
E Coli ◽  
K 12 ◽  
First Time

ABSTRACT Adherence of uropathogenic Escherichia coli to host tissue is required for infection and is mediated by fimbriae, such as pyelonephritis-associated pili (Pap). Expression of P fimbriae is regulated by phase variation, and to date, phase transition frequencies have been measured only for pap regulatory region constructs integrated into the E. coli K-12 chromosome. The aim of this work was to measure P phase transition frequencies in clinical isolates for the first time, including frequencies for the sequenced strain E. coli CFT073. P fimbriation and associated phase transition frequencies were measured for two E. coli clinical isolates and compared with levels for homologous pap constructs in E. coli K-12. Fimbriation and off-to-on transition frequencies were always higher in the clinical isolate. It was concluded that the regulatory inputs controlling papI expression are likely to be different in E. coli CFT073 and E. coli K-12 as (i) phase variation could be stimulated in E. coli K-12 by induction of papI and (ii) the level of expression of a papI::gfp + fusion was higher in E. coli CFT073 than in E. coli K-12. Furthermore, phase transition frequencies for the two E. coli CFT073 pap clusters were shown to be different depending on the culture conditions, indicating that there is a hierarchy of expression depending on signal inputs.

scholarly journals Regulation of lactate production and glucose transport as well as of glucose transporter 1 and lactate dehydrogenase A mRNA levels by basic fibroblast growth factor in rat Sertoli cells

2002 ◽  
Vol 173 (2) ◽  
pp. 335-343 ◽  
Author(s):  
MF Riera ◽  
SB Meroni ◽  
HF Schteingart ◽  
EH Pellizzari ◽  
SB Cigorraga
Keyword(s):  
Growth Factor ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Lactate Production ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Short Term ◽  
Glucose Transporter 1 ◽  
Ldh Activity

By using cultured rat Sertoli cells as a model, both the action of basic fibroblast growth factor (bFGF) on lactate production and the site of this action were studied. bFGF stimulated Sertoli cell lactate production in a dose-dependent manner (basal: 7.3+/-0.5; 0.1 ng/ml bFGF: 7.5+/-0.5; 1 ng/ml bFGF: 7.5+/-0.6; 10 ng/ml bFGF: 10.3+/-1.0; 30 ng/ml bFGF: 15.2+/-1.5; 50 ng/ml bFGF: 15.4+/-1.6 microg/microg DNA). Two major sites for the action of this growth factor were identified. First, bFGF was shown to exert short- and long-term stimulatory effects on glucose transport (basal: 1170+/-102; 30 ng/ml bFGF for 120 min: 1718+/-152 and basal: 718+/-64; 30 ng/ml bFGF for 48 h: 1069+/-69 d.p.m./microg DNA respectively). Short-term bFGF stimulation of glucose transport was not inhibited by the protein synthesis inhibitor cycloheximide. These results indicate that short-term bFGF stimulation of glucose uptake does not involve an increase in the number of glucose transporters. On the other hand, stimulation with bFGF for periods of time longer than 12 h increased glucose transporter 1 (GLUT1) mRNA levels. These increased mRNA levels were probably ultimately responsible for the increments in glucose uptake that are observed in long-term treated cultures. Secondly, bFGF increased lactate dehydrogenase (LDH) activity (basal: 31.0+/-1.4; 30 ng/ml bFGF: 45.7+/- 2.4 mIU/microg DNA). The principal subunit component of those LDH isozymes that favors the transformation of pyruvate to lactate is subunit A. bFGF increased LDH A mRNA levels in a dose- and time-dependent manner. In summary, the results presented herein show that glucose transport, LDH activity and GLUT1 and LDH A mRNA levels are regulated by bFGF to achieve an increase in lactate production. These observed regulatory actions provide unequivocal evidence of the participation of bFGF in Sertoli cell lactate production which may be related to normal germ cell development.

scholarly journals Regulation of pituitary inhibin/activin subunits and follistatin gene expression by GnRH in female rats

2011 ◽  
Vol 210 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Petra Popovics ◽  
Zoltan Rekasi ◽  
Alan J Stewart ◽  
Magdolna Kovacs
Keyword(s):  
Gene Expression ◽  
Mrna Level ◽  
Inhibin B ◽  
Female Rats ◽  
Pituitary Cells ◽  
Mrna Levels ◽  
Short Term ◽  
Α Subunit ◽  
Long Term Treatment

Pituitary inhibin B, activin B, and follistatin are local regulators of FSH. Activin B is a homodimeric molecule (βB–βB), while inhibin B contains an α and a βB subunit. The regulation of gene expression of α, βB, and follistatin by local and endocrine hormones was examined in pituitaries from female rats and in perifused pituitary cells by RT-PCR. Ovariectomy (OVX) induced an elevation in the mRNA level of α and βB subunits and follistatin. Short-term (4 h) treatment of pituitary cells with GnRH decreased both the inhibin α and the inhibin/activin βB subunit mRNA levels, while long-term treatment (20 h) with 100 nM GnRH stimulated the expression of both subunits. In contrast, the mRNA level of follistatin was elevated after the short-term GnRH treatment. Long-term exposure of pituitary cells to estradiol and inhibin B suppressed the mRNA expression of βB and had no effect on the expression of α subunit and follistatin. Our results demonstrate that the increased expressions of inhibin/activin subunits and follistatin in the post-OVX period can be induced by the lack of gonadal negative feedback, resulting in a high GnRH environment in the pituitary. This study reports for the first time that GnRH administered in high doses and for a long period stimulates the gene expression of inhibin/activin subunits and thereby may contribute to the stimulatory effect of OVX on the expression of these genes.

scholarly journals DNA Microarray Analyses of the Long-Term Adaptive Response of Escherichia coli to Acetate and Propionate

2003 ◽  
Vol 69 (3) ◽  
pp. 1759-1774 ◽  
Author(s):  
T. Polen ◽  
D. Rittmann ◽  
V. F. Wendisch ◽  
H. Sahm
Keyword(s):  
Escherichia Coli ◽  
Dna Microarray ◽  
Adaptive Response ◽  
Carbon Sources ◽  
Short Chain Fatty Acids ◽  
Adaptive Responses ◽  
General Stress Response ◽  
E Coli ◽  
Short Term Exposure

ABSTRACT In its natural environment, Escherichia coli is exposed to short-chain fatty acids, such as acetic acid or propionic acid, which can be utilized as carbon sources but which inhibit growth at higher concentrations. DNA microarray experiments revealed expression changes during exponential growth on complex medium due to the presence of sodium acetate or sodium propionate at a neutral external pH. The adaptive responses to acetate and propionate were similar and involved genes in three categories. First, the RNA levels for chemotaxis and flagellum genes increased. Accordingly, the expression of chromosomal fliC′-′lacZ and flhDC′-′lacZ fusions and swimming motility increased after adaptation to acetate or propionate. Second, the expression of many genes that are involved in the uptake and utilization of carbon sources decreased, indicating some kind of catabolite repression by acetate and propionate. Third, the expression of some genes of the general stress response increased, but the increases were more pronounced after short-term exposure for this response than for the adaptive response. Adaptation to propionate but not to acetate involved increased expression of threonine and isoleucine biosynthetic genes. The gene expression changes after adaptation to acetate or propionate were not caused solely by uncoupling or osmotic effects but represented specific characteristics of the long-term response of E. coli to either compound.

scholarly journals LPA stimulates intestinal DRA gene transcription via LPA2 receptor, PI3K/AKT, and c-Fos-dependent pathway

2012 ◽  
Vol 302 (6) ◽  
pp. G618-G627 ◽  
Author(s):  
Amika Singla ◽  
Anoop Kumar ◽  
Shubha Priyamvada ◽  
Maliha Tahniyath ◽  
Seema Saksena ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Gene Transcription ◽  
Promoter Activity ◽  
Intestinal Epithelial Cells ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Intestinal Epithelial ◽  
Short Term ◽  
Exchange Activity

DRA (downregulated in adenoma) or SLC26A3 is the major apical anion exchanger mediating Cl− absorption in intestinal epithelial cells. Disturbances in DRA function and expression have been implicated in diarrheal conditions such as congenital chloride diarrhea and inflammatory bowel diseases. Previous studies have shown that DRA is subject to regulation by short-term and transcriptional mechanisms. In this regard, we have recently shown that short-term treatment by lysophosphatidic acid (LPA), an important bioactive phospholipid, stimulates Cl−/HCO3−(OH−) exchange activity via an increase in DRA surface levels in human intestinal epithelial cells. However, the long-term effects of LPA on DRA at the level of gene transcription have not been examined. The present studies were aimed at investigating the effects of LPA on DRA function and expression as well as elucidating the mechanisms underlying its transcriptional regulation. Long-term LPA treatment increased the Cl−/HCO3− exchange activity in Caco-2 cells. LPA treatment (50–100 μM) of Caco-2 cells significantly stimulated DRA mRNA levels and DRA promoter activity (−1183/+114). This increase in DRA promoter activity involved the LPA2 receptor and phosphatidylinositol 3-kinase (PI3K)/AKT pathways. Progressive deletions from −1183/+114 to −790/+114 abrogated the stimulatory effects of LPA, indicating that the −1183/−790 promoter region harbors LPA response elements. Utilizing EMSA and mutational studies, our results showed that LPA induced the DRA promoter activity in a c-Fos-dependent manner. LPA also increased the protein expression of c-Fos and c-Jun in Caco-2 cells. Furthermore, overexpression of c-Fos but not c-Jun enhanced the DRA promoter activity. This increase in DRA transcription in response to LPA indicates that LPA may act as an antidiarrheal agent and could be exploited for the treatment of diarrhea associated with inflammatory or infectious diseases of the gut.

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