scholarly journals Identification of an Arsenic Resistance and Arsenic-Sensing System in Campylobacter jejuni

2009 ◽  
Vol 75 (15) ◽  
pp. 5064-5073 ◽  
Author(s):  
Liping Wang ◽  
Byeonghwa Jeon ◽  
Orhan Sahin ◽  
Qijing Zhang
Keyword(s):  
Campylobacter Jejuni ◽  
Molecular Mechanisms ◽  
Feed Additive ◽  
Pcr Analysis ◽  
Arsenic Resistance ◽  
Sensing System ◽  
Food Borne ◽  
Promoter Dna ◽  
Arsenic Sensing

ABSTRACT Arsenic is commonly present in the natural environment and is also used as a feed additive for animal production. Poultry is a major reservoir for Campylobacter jejuni, a major food-borne human pathogen causing gastroenteritis. It has been shown that Campylobacter isolates from poultry are highly resistant to arsenic compounds, but the molecular mechanisms responsible for the resistance have not been determined, and it is unclear if the acquired arsenic resistance affects the susceptibility of Campylobacter spp. to other antimicrobials. In this study, we identified a four-gene operon that contributes to arsenic resistance in Campylobacter. This operon encodes a putative membrane permease (ArsP), a transcriptional repressor (ArsR), an arsenate reductase (ArsC), and an efflux protein (Acr3). PCR analysis of various clinical C. jejuni isolates indicated a significant association of this operon with elevated resistance to arsenite and arsenate. Gene-specific mutagenesis confirmed the role of the ars operon in conferring arsenic resistance. It was further shown that this operon is subject to regulation by ArsR, which directly binds to the ars promoter and inhibits the transcription of the operon. Arsenite inhibits the binding of ArsR to the ars promoter DNA and induces the expression of the ars genes. Mutation of the ars genes did not affect the susceptibility of C. jejuni to commonly used antibiotics. These results identify the ars operon as an important mechanism for arsenic resistance and sensing in Campylobacter.

scholarly journals Insertional Inactivation of Prevotella intermedia OxyR Results in Reduced Survival with Oxidative Stress and in the Presence of Host Cells

2021 ◽  
Vol 9 (3) ◽  
pp. 551
Author(s):  
Mariko Naito ◽  
B. Ross Belvin ◽  
Mikio Shoji ◽  
Qin Gui ◽  
Janina P. Lewis
Keyword(s):  
Oxidative Stress ◽  
Molecular Mechanisms ◽  
Anaerobic Bacteria ◽  
Host Cells ◽  
Pcr Analysis ◽  
Prevotella Intermedia ◽  
Allelic Exchange ◽  
Important Target ◽  
Insertional Inactivation

One of the most abundant bacteria in the subgingival pockets of patients with bleeding following mechanical periodontal therapy is Prevotella intermedia. However, despite its abundance, the molecular mechanisms of its contribution to periodontal disease are not well known. This is mainly due to the lack of genetic tools that would allow examination of the role of predicted virulence factors in the pathogenesis of this bacterium. Here, we report on the first mutant in the P. intermedia OMA14 strain. The mutation is an allelic exchange replacement of the sequences coding for a putative OxyR regulator with ermF sequences coding for the macrolide–lincosamide resistance in anaerobic bacteria. The mutant is severely impaired in its ability to grow with eukaryotic cells, indicating that it is an important target for interventional strategies. Further analyses reveal that its ability to grow with oxidative stress species, in the form of hydrogen peroxide and oxygen, is severely affected. Transcriptome analysis reveals that the major deregulated genes code for the alkylhydroperoxide reductase system, AhpCF, mediating protection from peroxide stress. Moreover, genes coding for Dps, CydA and Ftn are downregulated in the mutant strain, as further verified using qRT-PCR analysis. In conclusion, we succeeded in generating the first P. intermedia mutant and show that the OxyR-deficient strain is unable to survive with a variety of host cells as well as with oxidative stress.

Identification and characterization of rice circular RNAs responding to Xanthomonas oryzae pv. oryzae invasion

2021 ◽  
Author(s):  
Peihong Wang ◽  
Sai Wang ◽  
Yan Wu ◽  
Wenhan Nie ◽  
Ayizekeranmu Yiming ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Enrichment Analysis ◽  
Xanthomonas Oryzae ◽  
Pcr Analysis ◽  
Circular Rnas ◽  
Transcriptional Gene Regulation ◽  
Identification And Characterization ◽  
Host Genes

Emerging role of circular RNAs (circRNAs) in various biological processes have advanced our knowledge of transcriptional and post-transcriptional gene regulation. To date, no research has been conducted to explore their roles in the rice- Xanthomonas oryzae pv. oryzae (Xoo) interaction. Therefore, we identified 3517 circRNAs from the highly virulent Xoo strain PXO99A-infected rice leaves using the ribosomal RNA (rRNA) depleted RNA-sequencing technique coupled with the CIRI2 and CIRCexplorer2 pipeline. Characterization analyses showed that these circRNAs were distributed across the whole genome of rice, and most circRNAs arised from exons (85.13 %), ranged from 200 bp to 1000 bp and were with a non-canonical GT/AG (including CT/AC equivalent) splicing signal. Functional annotation and enrichment analysis of the host genes that produced the DEcircRNAs suggested that these identified circRNAs might play an important role in reprogramming rice responses to PXO99A invasion, mainly by mediating photorespiration, chloroplast, peroxisome and diterpenoid biosynthesis. Moreover, 31 differentially expressed circRNAs (DEcircRNAs) were predicted to act as miRNA decoys in rice. The expression profile of 4 DEcircRNAs were validated by RT-qPCR with divergent primers, and the back-splicing sites of seven DEcircRNAs were verified by PCR analysis and Sanger sequencing. Collectively, these results inferred a potential functional role of circRNAs in the regulation of rice immunity and provide novel clues for revealing the molecular mechanisms of rice-PXO99A interaction.

Prevalence and characterization of quinolone resistance in Laribacter hongkongensis from grass carp and Chinese tiger frog

2013 ◽  
Vol 62 (10) ◽  
pp. 1559-1564 ◽  
Author(s):  
Ding-Qiang Chen ◽  
Ling Yang ◽  
Yu-Ting Luo ◽  
Min-Jie Mao ◽  
Yong-Ping Lin ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Efflux Pump ◽  
Quinolone Resistance ◽  
Efflux Pump Inhibitor ◽  
Electrophoretic Patterns ◽  
Food Borne ◽  
Laribacter Hongkongensis ◽  
Resistant Strains

Laribacter hongkongensis is a food-borne bacterium associated with community-acquired gastroenteritis and diarrhoea. Quinolone resistance was recently reported in bacterial isolates from aquatic products, but the molecular mechanisms for resistance were still unknown. In this study, a total of 157 L. hongkongensis strains were isolated from grass carps (n = 443) and Chinese tiger frogs (n = 171). Twenty-one ciprofloxacin-resistant strains were analysed for mutations in quinolone resistance-determining regions (QRDR), acquired quinolone resistance (AQR) genes and the role of efflux pumps in resistance. All QRDR mutations in gyrA (codons 85 and 89) and parC (codons 83 and 231) were found to be closely associated with ciprofloxacin resistance. The AQR gene aac(6′)-Ib-cr was found in 42.9 % (9/21) of the resistant strains, but qnrA, qnrB, qnrC, qnrD, qnrS and qepA were not detected. No significant change of MICs to ciprofloxacin was observed in the presence of an efflux pump inhibitor, indicating the role of efflux pump was probably absent. All 21 ciprofloxacin-resistant strains showed different electrophoretic patterns, which suggested they were not genetically related. These data highlight the importance of QRDR mutations and the AQR gene aac(6′)-Ib-cr during the development of quinolone resistance in a heterogeneous population of L. hongkongensis.

scholarly journals Identification of a Novel Membrane Transporter Mediating Resistance to Organic Arsenic in Campylobacter jejuni

2014 ◽  
Vol 58 (4) ◽  
pp. 2021-2029 ◽  
Author(s):  
Zhangqi Shen ◽  
Taradon Luangtongkum ◽  
Zhiyi Qiang ◽  
Byeonghwa Jeon ◽  
Liping Wang ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Type Strain ◽  
Wild Type Strain ◽  
Inorganic Arsenic ◽  
Feed Additive ◽  
Membrane Transporter ◽  
Wild Type ◽  
Arsenic Resistance ◽  
Content Type ◽  
Organic Arsenic

ABSTRACTAlthough bacterial mechanisms involved in the resistance to inorganic arsenic are well understood, the molecular basis for organic arsenic resistance has not been described.Campylobacter jejuni, a major food-borne pathogen causing gastroenteritis in humans, is highly prevalent in poultry and is reportedly resistant to the arsenic compound roxarsone (4-hydroxy-3-nitrobenzenearsonic acid), which has been used as a feed additive in the poultry industry for growth promotion. In this study, we report the identification of a novel membrane transporter (named ArsP) that contributes to organic arsenic resistance inCampylobacter. ArsP is predicted to be a membrane permease containing eight transmembrane helices, distinct from other known arsenic transporters. Analysis of multipleC. jejuniisolates from various animal species revealed that the presence of an intactarsPgene is associated with elevated resistance to roxarsone. In addition, inactivation ofarsPinC. jejuniresulted in 4- and 8-fold reductions in the MICs of roxarsone and nitarsone, respectively, compared to that for the wild-type strain. Furthermore, cloning ofarsPinto aC. jejunistrain lacking a functionalarsPgene led to 16- and 64-fold increases in the MICs of roxarsone and nitarsone, respectively. Neither mutation nor overexpression ofarsPaffected the MICs of inorganic arsenic, including arsenite and arsenate, inCampylobacter. Moreover, acquisition ofarsPin NCTC 11168 led to accumulation of less roxarsone than the wild-type strain lackingarsP. Together, these results indicate that ArsP functions as an efflux transporter specific for extrusion of organic arsenic and contributes to the resistance to these compounds inC. jejuni.

An outbreak of food-borne Campylobacter jejuni infection and the possible role of cross-contamination

1988 ◽  
Vol 17 (2) ◽  
pp. 171-176 ◽  
Author(s):  
P. Brown ◽  
D. Kidd ◽  
T. Riordan ◽  
R.A. Barrell
Keyword(s):  
Campylobacter Jejuni ◽  
Cross Contamination ◽  
Food Borne

scholarly journals TFF1 Induces Aggregation and Reduces Motility of Helicobacter pylori

2021 ◽  
Vol 22 (4) ◽  
pp. 1851
Author(s):  
Daniela Eletto ◽  
Megi Vllahu ◽  
Fatima Mentucci ◽  
Pasquale Del Gaudio ◽  
Antonello Petrella ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Molecular Mechanisms ◽  
Protective Role ◽  
Pcr Analysis ◽  
Long Time ◽  
H Pylori ◽  
Flab Gene ◽  
Trefoil Factor 1

Gastric cancer is considered one of the most common malignancies in humans and Helicobacter pylori infection is the major environmental risk factor of gastric cancer development. Given the high spread of this bacterium whose infection is mostly asymptomatic, H. pylori colonization persists for a long time, becoming chronic and predisposing to malignant transformation. The first defensive barrier from bacterial infection is constituted by the gastric mucosa that secretes several protective factors, among which is the trefoil factor 1 (TFF1), that, as mucin 5AC, binds the bacterium. Even if the protective role of TFF1 is well-documented, the molecular mechanisms that confer a beneficial function to the interaction among TFF1 and H. pylori remain still unclear. Here we analyze the effects of this interaction on H. pylori at morphological and molecular levels by means of microscopic observation, chemiotaxis and motility assays and real-time PCR analysis. Our results show that TFF1 favors aggregation of H. pylori and significantly slows down the motility of the bacterium across the mucus. Such aggregates significantly reduce both flgE and flaB gene transcription compared with bacteria not incubated with TFF1. Finally, our results suggest that the interaction between TFF1 and the bacterium may explain the frequent persistence of H. pylori in the human host without inducing disease.

How do histone modifications contribute to transgenerational epigenetic inheritance in C. elegans?

2020 ◽  
Vol 48 (3) ◽  
pp. 1019-1034 ◽  
Author(s):  
Rachel M. Woodhouse ◽  
Alyson Ashe
Keyword(s):  
Histone Modifications ◽  
Molecular Mechanisms ◽  
Epigenetic Inheritance ◽  
Nematode Caenorhabditis Elegans ◽  
Histone Methyltransferases ◽  
Transgenerational Epigenetic Inheritance ◽  
C Elegans ◽  
Recent Developments ◽  
Gene Regulatory

Gene regulatory information can be inherited between generations in a phenomenon termed transgenerational epigenetic inheritance (TEI). While examples of TEI in many animals accumulate, the nematode Caenorhabditis elegans has proven particularly useful in investigating the underlying molecular mechanisms of this phenomenon. In C. elegans and other animals, the modification of histone proteins has emerged as a potential carrier and effector of transgenerational epigenetic information. In this review, we explore the contribution of histone modifications to TEI in C. elegans. We describe the role of repressive histone marks, histone methyltransferases, and associated chromatin factors in heritable gene silencing, and discuss recent developments and unanswered questions in how these factors integrate with other known TEI mechanisms. We also review the transgenerational effects of the manipulation of histone modifications on germline health and longevity.

Mesophyll conductance: the leaf corridors for photosynthesis

2020 ◽  
Vol 48 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Jorge Gago ◽  
Danilo M. Daloso ◽  
Marc Carriquí ◽  
Miquel Nadal ◽  
Melanie Morales ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Main Role ◽  
Mesophyll Conductance ◽  
Future Studies ◽  
Cell Structures ◽  
Leaf Tissues ◽  
Change Framework ◽  
Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

The Role of the Endothelium in Premature Atherosclerosis: Molecular Mechanisms

2020 ◽  
Vol 27 (7) ◽  
pp. 1041-1051 ◽  
Author(s):  
Michael Spartalis ◽  
Eleftherios Spartalis ◽  
Antonios Athanasiou ◽  
Stavroula A. Paschou ◽  
Christos Kontogiannis ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Low Density Lipoprotein ◽  
Critical Role ◽  
Density Lipoprotein ◽  
Number Of Genes ◽  
Causes Of Mortality ◽  
Artery Disease ◽  
Genetic And Environmental Factors ◽  
Made In

Atherosclerotic disease is still one of the leading causes of mortality. Atherosclerosis is a complex progressive and systematic artery disease that involves the intima of the large and middle artery vessels. The inflammation has a key role in the pathophysiological process of the disease and the infiltration of the intima from monocytes, macrophages and T-lymphocytes combined with endothelial dysfunction and accumulated oxidized low-density lipoprotein (LDL) are the main findings of atherogenesis. The development of atherosclerosis involves multiple genetic and environmental factors. Although a large number of genes, genetic polymorphisms, and susceptible loci have been identified in chromosomal regions associated with atherosclerosis, it is the epigenetic process that regulates the chromosomal organization and genetic expression that plays a critical role in the pathogenesis of atherosclerosis. Despite the positive progress made in understanding the pathogenesis of atherosclerosis, the knowledge about the disease remains scarce.

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