Differential regulation of interchromosomal copies of ToxR-induced genes

2007 ◽  
Vol 53 (8) ◽  
pp. 992-999
Author(s):  
Sanjay Nag ◽  
Keya Chaudhuri
Keyword(s):  
Virulence Genes ◽  
Ph Effect ◽  
Low Ph ◽  
Insertion Mutant ◽  
Wild Type ◽  
Rt Pcr ◽  
Transcription Profiling ◽  
Environmental Signals ◽  
Chromosome Ii ◽  
Chromosome I

In Vibrio cholerae , ToxR transcriptionally activates a number of virulence genes in response to various environmental signals. In the present study, transcription profiling by macroarray was carried out with 13 pairs of genes, one copy of which is present in each chromosome under ToxR-inducing (pH 6.5, osmolarity 66 mmol/L, 30 °C) and ToxR-repressing (pH 8.5, osmolarity 300 mmol/L, 37 °C) conditions followed by high pH (8.5) and low pH (6.5) conditions to eliminate pH effect. The genes dacAII, tagEII, secDII, pmmI, pmmII, and immII showed increased expression in the ToxR-inducing conditions, but not at low pH, suggesting that the expression of these genes might be regulated by ToxR. The expression of pmmII, dacAII, tagEII, secDII, and immII genes decreased significantly in the toxR insertion mutant as determined by RT–PCR, whereas the expression of the chromosome I copy of pmm increased in toxR mutant compared with wild-type cells. Thus, the chromosome II copy of these genes, which show increased expression under ToxR-inducing conditions, are all regulated by ToxR in V. cholerae, whereas the chromosome I copy of pmm may be regulated by other factors under ToxR-inducing conditions.

scholarly journals Mechanisms of sod2 Gene Amplification inSchizosaccharomyces pombe

2000 ◽  
Vol 11 (3) ◽  
pp. 873-886 ◽  
Author(s):  
Elizabeth B. Albrecht ◽  
Aaron B. Hunyady ◽  
George R. Stark ◽  
Thomas E. Patterson
Keyword(s):  
Gene Amplification ◽  
Base Pair ◽  
Dna Lesions ◽  
The Novel ◽  
Wild Type ◽  
Resistant Mutants ◽  
Chromosome Ii ◽  
Chromosome I ◽  
Mutant Cells ◽  
Type Strains

Gene amplification in eukaryotes plays an important role in drug resistance, tumorigenesis, and evolution. TheSchizosaccharomyces pombe sod2 gene provides a useful model system to analyze this process. sod2 is near the telomere of chromosome I and encodes a plasma membrane Na+(Li+)/H+ antiporter. Whensod2 is amplified, S. pombe survives otherwise lethal concentrations of LiCl, and >90% of the amplifiedsod2 genes are found in 180- and 225-kilobase (kb) linear amplicons. The sequence of the novel joint of the 180-kb amplicon indicates that it is formed by recombination between homologous regions near the telomeres of the long arm of chromosome I and the short arm of chromosome II. The 225-kb amplicon, isolated three times more frequently than the 180-kb amplicon, is a palindrome derived from a region near the telomere of chromosome I. The center of symmetry of this palindrome contains an inverted repeat consisting of two identical 134-base pair sequences separated by a 290-base pair spacer. LiCl-resistant mutants arise 200–600 times more frequently in strains deficient for topoisomerases or DNA ligase activity than in wild-type strains, but the mutant cells contain the same amplicons. These data suggest that amplicon formation may begin with DNA lesions such as breaks. In the case of the 225-kb amplicon, the breaks may lead to a hairpin structure, which is then replicated to form a double-stranded linear amplicon, or to a cruciform structure, which is then resolved to yield the same amplicon.

scholarly journals Genetic Locus Required for Antigenic Maturation of Rhizobium etli CE3 Lipopolysaccharide

2001 ◽  
Vol 183 (20) ◽  
pp. 6054-6064 ◽  
Author(s):  
Dominik M. Duelli ◽  
Andrea Tobin ◽  
Jodie M. Box ◽  
V. S. Kumar Kolli ◽  
Russell W. Carlson ◽  
...  
Keyword(s):  
Genetic Locus ◽  
Low Ph ◽  
Open Reading Frames ◽  
Site Directed Mutagenesis ◽  
Nodule Development ◽  
Environmental Cues ◽  
Rhizobium Etli ◽  
Wild Type ◽  
Specific Expression ◽  
Environmental Signals

ABSTRACT Rhizobium etli modifies lipopolysaccharide (LPS) structure in response to environmental signals, such as low pH and anthocyanins. These LPS modifications result in the loss of reactivity with certain monoclonal antibodies. The same antibodies fail to recognize previously isolated R. etli mutant strain CE367, even in the absence of such environmental cues. Chemical analysis of the LPS in strain CE367 demonstrated that it lacked the terminal sugar of the wild-type O antigen, 2,3,4-tri-O-methylfucose. A 3-kb stretch of DNA, designated as lpe3, restored wild-type antigenicity when transferred into CE367. From the sequence of this DNA, five open reading frames were postulated. Site-directed mutagenesis and complementation analysis suggested that the genes were organized in at least two transcriptional units, both of which were required for the production of LPS reactive with the diagnostic antibodies. Growth in anthocyanins or at low pH did not alter the specific expression ofgusA from the transposon insertion of mutant CE367, nor did the presence of multiple copies of lpe3 situated behind a strong, constitutive promoter prevent epitope changes induced by these environmental cues. Mutations of the lpe genes did not prevent normal nodule development on Phaseolus vulgaris and had very little effect on the occupation of nodules in competition with the wild-type strain.

scholarly journals Changes in Nucleoid Morphology and Origin Localization upon Inhibition or Alteration of the Actin Homolog, MreB, of Vibrio cholerae

2007 ◽  
Vol 189 (20) ◽  
pp. 7450-7463 ◽  
Author(s):  
Preeti Srivastava ◽  
Gäelle Demarre ◽  
Tatiana S. Karpova ◽  
James McNally ◽  
Dhruba K. Chattoraj
Keyword(s):  
Escherichia Coli ◽  
Vibrio Cholerae ◽  
Chromosome Segregation ◽  
Cell Shape ◽  
Caulobacter Crescentus ◽  
Wild Type ◽  
E Coli ◽  
The One ◽  
Chromosome Ii ◽  
Chromosome I

ABSTRACT MreB is an actin homolog required for the morphogenesis of most rod-shaped bacteria and for other functions, including chromosome segregation. In Caulobacter crescentus and Escherichia coli, the protein seems to play a role in the segregation of sister origins, but its role in Bacillus subtilis chromosome segregation is less clear. To help clarify its role in segregation, we have here studied the protein in Vibrio cholerae, whose chromosome I segregates like the one in C. crescentus and whose chromosome II like the one in E. coli or B. subtilis. The properties of Vibrio MreB were similar to those of its homologs in other bacteria in that it formed dynamic helical filaments, was essential for viability, and was inhibited by the drug A22. Wild-type (WT) cells exposed to A22 became spherical and larger. The nucleoids enlarged correspondingly, and the origin positions for both the chromosomes no longer followed any fixed pattern. However, the sister origins separated, unlike the situation in other bacteria. In mutants isolated as A22 resistant, the nucleoids in some cases appeared compacted even when the cell shape was nearly normal. In these cells, the origins of chromosome I were at the distal edges of the nucleoid but not all the way to the poles where they normally reside. The sister origins of chromosome II also separated less. Thus, it appears that the inhibition or alteration of Vibrio MreB can affect both the nucleoid morphology and origin localization.

scholarly journals The Lipid Lysyl-Phosphatidylglycerol Is Present in Membranes of Rhizobium tropici CIAT899 and Confers Increased Resistance to Polymyxin B Under Acidic Growth Conditions

2007 ◽  
Vol 20 (11) ◽  
pp. 1421-1430 ◽  
Author(s):  
Christian Sohlenkamp ◽  
Kanaan A. Galindo-Lagunas ◽  
Ziqiang Guan ◽  
Pablo Vinuesa ◽  
Sally Robinson ◽  
...  
Keyword(s):  
Sinorhizobium Meliloti ◽  
Minimal Medium ◽  
Polymyxin B ◽  
Growth Conditions ◽  
Membrane Lipid ◽  
Low Ph ◽  
Wild Type ◽  
Rhizobium Tropici ◽  
Gram Negative ◽  
Inducible Genes

Lysyl-phosphatidylglycerol (LPG) is a well-known membrane lipid in several gram-positive bacteria but is almost unheard of in gram-negative bacteria. In Staphylococcus aureus, the gene product of mprF is responsible for LPG formation. Low pH-inducible genes, termed lpiA, have been identified in the gram-negative α-proteobacteria Rhizobium tropici and Sinorhizobium medicae in screens for acid-sensitive mutants and they encode homologs of MprF. An analysis of the sequenced bacterial genomes reveals that genes coding for homologs of MprF from S. aureus are present in several classes of organisms throughout the bacterial kingdom. In this study, we show that the expression of lpiA from R. tropici in the heterologous hosts Escherichia coli and Sinorhizobium meliloti causes formation of LPG. A wild-type strain of R. tropici forms LPG (about 1% of the total lipids) when the cells are grown in minimal medium at pH 4.5 but not when grown in minimal medium at neutral pH or in complex tryptone yeast (TY) medium at either pH. LPG biosynthesis does not occur when lpiA is deleted and is restored upon complementation of lpiA-deficient mutants with a functional copy of the lpiA gene. When grown in the low-pH medium, lpiA-deficient rhizobial mutants are over four times more susceptible to the cationic peptide polymyxin B than the wild type.

scholarly journals The Cloning and Molecular Analysis of pawn-B in Paramecium tetraurelia

Genetics ◽  
2000 ◽  
Vol 155 (3) ◽  
pp. 1105-1117 ◽  
Author(s):  
W John Haynes ◽  
Kit-Yin Ling ◽  
Robin R Preston ◽  
Yoshiro Saimi ◽  
Ching Kung
Keyword(s):  
Genomic Library ◽  
Open Reading Frame ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Rt Pcr ◽  
Reading Frame ◽  
Close Proximity ◽  
In The Wild ◽  
Dna Fragment ◽  
Alternative Sites

Abstract Pawn mutants of Paramecium tetraurelia lack a depolarization-activated Ca2+ current and do not swim backward. Using the method of microinjection and sorting a genomic library, we have cloned a DNA fragment that complements pawn-B (pwB/pwB). The minimal complementing fragment is a 798-bp open reading frame (ORF) that restores the Ca2+ current and the backward swimming when expressed. This ORF contains a 29-bp intron and is transcribed and translated. The translated product has two putative transmembrane domains but no clear matches in current databases. Mutations in the available pwB alleles were found within this ORF. The d4-95 and d4-96 alleles are single base substitutions, while d4-662 (previously pawn-D) harbors a 44-bp insertion that matches an internal eliminated sequence (IES) found in the wild-type germline DNA except for a single C-to-T transition. Northern hybridizations and RT-PCR indicate that d4-662 transcripts are rapidly degraded or not produced. A second 155-bp IES in the wild-type germline ORF excises at two alternative sites spanning three asparagine codons. The pwB ORF appears to be separated from a 5′ neighboring ORF by only 36 bp. The close proximity of the two ORFs and the location of the pwB protein as indicated by GFP-fusion constructs are discussed.

scholarly journals FGFR3 overexpression is a useful detection tool for FGFR3 fusions and sequence variations in glioma

2020 ◽  
Author(s):  
Jens Schittenhelm ◽  
Lukas Ziegler ◽  
Jan Sperveslage ◽  
Michel Mittelbronn ◽  
David Capper ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Growth Factor Receptor ◽  
Gene Mutations ◽  
Diagnostic Tools ◽  
Wild Type ◽  
Rt Pcr ◽  
Fgfr3 Gene ◽  
Detection Tool ◽  
Sequence Variations ◽  
Gene Panel Sequencing

Abstract Background Fibroblast growth factor receptor (FGFR) inhibitors are currently used in clinical development. A subset of glioblastomas carries gene fusion of FGFR3 and transforming acidic coiled-coil protein 3. The prevalence of other FGFR3 alterations in glioma is currently unclear. Methods We performed RT-PCR in 101 glioblastoma samples to detect FGFR3-TACC3 fusions (“RT-PCR cohort”) and correlated results with FGFR3 immunohistochemistry (IHC). Further, we applied FGFR3 IHC in 552 tissue microarray glioma samples (“TMA cohort”) and validated these results in two external cohorts with 319 patients. Gene panel sequencing was carried out in 88 samples (“NGS cohort”) to identify other possible FGFR3 alterations. Molecular modeling was performed on newly detected mutations. Results In the “RT-PCR cohort,” we identified FGFR3-TACC3 fusions in 2/101 glioblastomas. Positive IHC staining was observed in 73/1024 tumor samples of which 10 were strongly positive. In the “NGS cohort,” we identified FGFR3 fusions in 9/88 cases, FGFR3 amplification in 2/88 cases, and FGFR3 gene mutations in 7/88 cases in targeted sequencing. All FGFR3 fusions and amplifications and a novel FGFR3 K649R missense mutation were associated with FGFR3 overexpression (sensitivity and specificity of 93% and 95%, respectively, at cutoff IHC score > 7). Modeling of these data indicated that Tyr647, a residue phosphorylated as a part of FGFR3 activation, is affected by the K649R mutation. Conclusions FGFR3 IHC is a useful screening tool for the detection of FGFR3 alterations and could be included in the workflow for isocitrate dehydrogenase (IDH) wild-type glioma diagnostics. Samples with positive FGFR3 staining could then be selected for NGS-based diagnostic tools.

scholarly journals CORRIGENDUM

Genetics ◽  
1987 ◽  
Vol 115 (3) ◽  
pp. 579-579
Keyword(s):  
Sister Chromatid ◽  
Recombination Event ◽  
Linear Plasmid ◽  
Wild Type ◽  
Spore Viability ◽  
Yeast Plasmid ◽  
Type Locus ◽  
Sister Chromatids ◽  
Chromosome Ii ◽  
Meiosis I

ABSTRACT In the paper by Jules O'Rear and Jasper Rine (Genetics  113: 517-529; July, 1986) entitled "Precocious meiotic centromere separation of a novel yeast chromosome," the authors described a gene conversion event between a linear yeast plasmid carrying a LYS2 gene and a mutant lys2 gene at the wild-type locus on chromosome II. When these yeasts were mated to wild-type yeast and the resulting diploids sporulated, linked markers on the linear plasmid showed unusual segregation and poor spore viability was observed. On the basis of these observations, we proposed that the recombination event between the linear plasmid and chromosome II had split chromosome II into two fragments, one of which carried the normal centromere of chromosome II (fragment IIa) and the other, a telocentric fragment (fragment IIb), carried the centromere present on the linear plasmid. Separation of the chromosomes from these cells on OFAGE gels verified that chromosome II had been split into two fragments. Furthermore, we proposed that the sister chromatids of the telocentric fragment (fragment IIb) separated precociously in meiosis I when complete chromosome II and fragment IIa were present. In discussions with colleagues, an alternative explanation arose in which a recombination event between a sister chromatid of fragment IIa and a sister chromatid of chromosome II would result in each chromosome II chromatid being joined to a fragment IIa chromatid at CEN2. The two daughter cells of meiosis I would therefore each receive one chromatid of fragment IIa and one chromatid of chromosome II. Segregation of the two sister chromatids of fragment IIb to one pole in meiosis I without precocious centromere separation would result in the observed tetrad classes. To distinguish between these two mechanisms, a centromere-linked marker was introduced into the cross between the strain containing the two fragments of chromosome II and a wild-type strain. Tetrad analysis of the resulting diploid is consistent with the recombination model for the poor spore viability and inconsistent with precocious centromere separation. We thank Drs. Eric Lambie, Michael Lichten and Tom Petes for helpful discussions.

Inflammatory Chemokines Expression Variations and Their Receptors in APP/PS1 Mice

2021 ◽  
pp. 1-10
Author(s):  
Adrián Jorda ◽  
Martin Aldasoro ◽  
Constanza Aldasoro ◽  
Soraya L. Valles
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Chemokine Receptors ◽  
Presenilin 1 ◽  
Wild Type ◽  
Rt Pcr ◽  
New Strategy ◽  
Inflammatory Chemokines ◽  
Inflammatory Changes ◽  
Old Mice

Background: In Alzheimer’s disease (AD), an increase in inflammation is distinctive. Amyloid precursor protein plus presenilin-1 (APP/PS1 mice) is a model for this illness. Chemokines secreted by central nervous system (CNS) cells could play multiple important roles in AD. Data looking for the chemokines involved in inflammatory mechanisms are lacking. To understand the changes that occur in the inflammation process in AD, it is necessary to improve strategies to act on specific inflammatory targets. Objective: Chemokines and their receptors involved in phagocytosis, demyelination, chemotaxis, and coagulation were the objective of our study. Methods: Female APPswe/PS1 double-transgenic mice (B6C3-Tg) were used and cortex brain from 20–22-month-old mice obtained and used to quantify chemokines and chemokine receptors expression using RT-PCR technique. Results: Significant inflammatory changes were detected in APP/PS1 compared to wild type mice. CCR1, CCR3, CCR4, and CCR9 were elevated, and CCR2 were decreased compared with wild type mice. Their ligands CCL7, CCL11, CCL17, CCL22, CCL25, and CXCL4 showed an increase expression; however, changes were not observed in CCL2 in APP/PS1 compared to wild type mice. Conclusion: This change in expression could explain the differences between AD patients and elderly people without this illness. This would provide a new strategy for the treatment of AD, with the possibility to act in specific inflammatory targets.

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