scholarly journals Discerning role of a functional arsenic resistance cassette in evolution and adaptation of a rice pathogen

2020 ◽  
Author(s):  
Amandeep Kaur ◽  
Rekha Rana ◽  
Tanu Saroha ◽  
Prabhu B. Patil
Keyword(s):  
Plant Pathogen ◽  
Iron Acquisition ◽  
Arsenic Exposure ◽  
Resistance Mechanism ◽  
Transcriptional Response ◽  
Inorganic Arsenic ◽  
Arsenic Species ◽  
Selective Advantage ◽  
Arsenic Resistance

AbstractArsenic (As) is highly toxic element to all forms of life and is a major environmental contaminant. Understanding acquisition, detoxification, and adaptation mechanisms in bacteria that are associated with host in arsenic-rich conditions can provide novel insights into dynamics of host-microbe-microenvironment interactions. In the present study, we have investigated an arsenic resistance mechanism acquired during the evolution of a particular lineage in the population of Xanthomonas oryzae pv. oryzae (Xoo), which is a serious plant pathogen infecting rice. Our study revealed the horizontal acquisition of a novel chromosomal 12kb ars cassette in Xoo IXO1088 that confers high resistance to arsenate/arsenite. The ars cassette comprises several genes that constitute an operon induced in the presence of arsenate/arsenite. Transfer of cloned ars cassette to Xoo BXO512 lacking it confers arsenic resistance phenotype. Further, the transcriptional response of Xoo IXO1088 under arsenate/arsenite exposure was analyzed using RNA sequencing. Arsenic detoxification and efflux, oxidative stress, iron acquisition/storage, and damage repair are the main cellular responses to arsenic exposure. Our investigation has provided novel insights in to how a pathogenic bacterium is coping with arsenic-rich unique micro-environments like seen in rice growing in submerged water conditions.Impact statementArsenic accumulation in rice is a serious and unique agronomic issue. Arsenic contaminated groundwater used for irrigation purposes is adding to the accumulation of arsenic in rice. Submerged conditions in the paddy fields further induce the prevalence of toxic inorganic arsenic species in the environment. Our genomics and transcriptomics-based study reveals how a rice pathogen is coping with the lethal concentrations of arsenic by acquiring a novel resistance cassette during diversification into lineages. Acquisition of such detoxification mechanisms can provide a selective advantage to the bacterial population in avoiding toxicity or enhancing virulence and to their on-going evolutionary events. While there are numerous studies on plant-pathogen-environment interactions, our study highlights the importance of systematic studies on the role of unique micro-environmental conditions on the evolution of host-adapted pathogens/microbes.

scholarly journals Discerning the role of a functional arsenic-resistance cassette in the evolution and adaptation of a rice pathogen

2021 ◽  
Vol 7 (7) ◽  
Author(s):  
Amandeep Kaur ◽  
Rekha Rana ◽  
Tanu Saroha ◽  
Prabhu B. Patil
Keyword(s):  
Type Species ◽  
Evolutionary Dynamics ◽  
Iron Acquisition ◽  
Arsenic Exposure ◽  
Resistance Mechanism ◽  
Transcriptional Response ◽  
Adaptation Mechanism ◽  
Arsenic Resistance ◽  
Content Type ◽  
Link Type

Arsenic is highly toxic element to all forms of life and is a major environmental contaminant. Understanding acquisition, detoxification and adaptation mechanisms in bacteria that are associated with the host in arsenic-rich conditions can provide novel insights into the evolutionary dynamics of host–microbe–environment interactions. In the present study, we have investigated an arsenic-resistance mechanism acquired during the evolution of a particular lineage in the population of Xanthomonas oryzae pv. oryzae, which is a serious plant pathogen infecting rice. Our study revealed the horizontal acquisition of a novel chromosomal 12 kb ars cassette in X. oryzae pv. oryzae IXO1088 that confers high resistance to arsenate/arsenite. The ars cassette comprises several genes that constitute an operon induced in the presence of arsenate/arsenite. Transfer of the cloned ars cassette to X. oryzae pv. oryzae BXO512, which lacks the cassette, confers an arsenic-resistance phenotype. Furthermore, the transcriptional response of X. oryzae pv. oryzae IXO1088 under arsenate/arsenite exposure was analysed using RNA sequencing. Arsenic detoxification and efflux, oxidative stress, iron acquisition/storage, and damage repair are the main cellular responses to arsenic exposure. Our investigation has provided insights into the existence of a novel detoxification and adaptation mechanism within the X. oryzae pv. oryzae population to deal with high-arsenic conditions outside the rice plant.

scholarly journals Arsenic Methyltransferase and Methylation of Inorganic Arsenic

Biomolecules ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1351
Author(s):  
Nirmal K. Roy ◽  
Anthony Murphy ◽  
Max Costa
Keyword(s):  
Oxidative Stress ◽  
Skin Color ◽  
Arsenic Exposure ◽  
Inorganic Arsenic ◽  
Arsenic Species ◽  
Amino Acid Sequences ◽  
Health Concern ◽  
Dimethylarsinic Acid ◽  
Nucleotide Polymorphisms ◽  
Foot Disease

Arsenic occurs naturally in the environment, and exists predominantly as inorganic arsenite (As (III) and arsenate As (V)). Arsenic contamination of drinking water has long been recognized as a major global health concern. Arsenic exposure causes changes in skin color and lesions, and more severe health conditions such as black foot disease as well as various cancers originating in the lungs, skin, and bladder. In order to efficiently metabolize and excrete arsenic, it is methylated to monomethylarsonic and dimethylarsinic acid. One single enzyme, arsenic methyltransferase (AS3MT) is responsible for generating both metabolites. AS3MT has been purified from several mammalian and nonmammalian species, and its mRNA sequences were determined from amino acid sequences. With the advent of genome technology, mRNA sequences of AS3MT have been predicted from many species throughout the animal kingdom. Horizontal gene transfer had been postulated for this gene through phylogenetic studies, which suggests the importance of this gene in appropriately handling arsenic exposures in various organisms. An altered ability to methylate arsenic is dependent on specific single nucleotide polymorphisms (SNPs) in AS3MT. Reduced AS3MT activity resulting in poor metabolism of iAs has been shown to reduce expression of the tumor suppressor gene, p16, which is a potential pathway in arsenic carcinogenesis. Arsenic is also known to induce oxidative stress in cells. However, the presence of antioxidant response elements (AREs) in the promoter sequences of AS3MT in several species does not correlate with the ability to methylate arsenic. ARE elements are known to bind NRF2 and induce antioxidant enzymes to combat oxidative stress. NRF2 may be partly responsible for the biotransformation of iAs and the generation of methylated arsenic species via AS3MT. In this article, arsenic metabolism, excretion, and toxicity, a discussion of the AS3MT gene and its evolutionary history, and DNA methylation resulting from arsenic exposure have been reviewed.

Impact of carbon nanotubes on the toxicity of inorganic arsenic [AS(III) and AS(V)] toDaphnia magna: The role of certain arsenic species

2016 ◽  
Vol 35 (7) ◽  
pp. 1852-1859 ◽  
Author(s):  
Xinghao Wang ◽  
Ruijuan Qu ◽  
Ahmed A. Allam ◽  
Jamaan Ajarem ◽  
Zhongbo Wei ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Inorganic Arsenic ◽  
Arsenic Species

scholarly journals Exposure Levels and Contributing Factors of Various Arsenic Species and Their Health Effects on Korean Adults

2021 ◽  
Author(s):  
Seul-Gi Lee ◽  
Ingu Kang ◽  
Mi-Na Seo ◽  
Jung-Eum Lee ◽  
Sang-Yong Eom ◽  
...  
Keyword(s):  
Health Effects ◽  
Geometric Mean ◽  
Arsenic Exposure ◽  
Inorganic Arsenic ◽  
Arsenic Species ◽  
Exposure Level ◽  
Dimethylarsinic Acid ◽  
Contributing Factors ◽  
C Peptide ◽  
Korean Adults

Abstract Arsenic is a human carcinogen. Data on urinary arsenic species analyses of Koreans is limited. This study evaluated the arsenic exposure level, contributing factors, and health effects in Korean adults. Dietary intake information and urine samples were obtained from 2,044 participants. Arsenic exposure was assessed based on urinary concentrations of arsenic species, such as inorganic arsenic, As(III) and As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and arsenobetaine (AsB), using high-performance liquid chromatography with inductively coupled plasma mass spectrometry, followed by determination of biomarkers, malondialdehyde and c-peptide. The geometric mean concentrations were 30.9 ㎍/L for the sum of inorganic arsenic and their metabolites, and 84.7 ㎍/L for the total sum of arsenic measured. Urinary concentrations of arsenic species were influenced by age, inhabitant area (inland or coastal), and seafood intake, which was positively correlated with inorganic arsenic, DMA, and AsB. Rice intake was positively correlated with inorganic arsenic and its metabolites but not with AsB. Additionally, malondialdehyde and c-peptide levels were significantly associated with urinary concentrations of various arsenic species. Seafood and rice are major sources of organic/inorganic arsenic exposure in Korean adults; however, it is necessary to evaluate whether their overconsumption could have a potentially detrimental effect on human health.

scholarly journals Transcriptome Analysis Reveals New Insights into the Bacterial Wilt Resistance Mechanism Mediated by Silicon in Tomato

2019 ◽  
Vol 20 (3) ◽  
pp. 761 ◽  
Author(s):  
Nihao Jiang ◽  
Xueying Fan ◽  
Weipeng Lin ◽  
Guoping Wang ◽  
Kunzheng Cai
Keyword(s):  
Water Deficit ◽  
Stress Responses ◽  
Bacterial Wilt ◽  
Resistance Mechanism ◽  
Transcriptional Response ◽  
Differentially Expressed ◽  
Water Deficit Stress ◽  
Post Inoculation ◽  
Molecular Pattern

Bacterial wilt is a devastating disease of tomato caused by soilborne pathogenic bacterium Ralstonia solanacearum. Previous studies found that silicon (Si) can increase tomato resistance against R. solanacearum, but the exact molecular mechanism remains unclear. RNA sequencing (RNA-Seq) technology was used to investigate the dynamic changes of root transcriptome profiles between Si-treated (+Si) and untreated (−Si) tomato plants at 1, 3, and 7 days post-inoculation with R. solanacearum. The contents of salicylic acid (SA), ethylene (ET), and jasmonic acid (JA) and the activity of defense-related enzymes in roots of tomato in different treatments were also determined. The burst of ET production in roots was delayed, and SA and JA contents were altered in Si treatment. The transcriptional response to R. solanacearum infection of the +Si plants was quicker than that of the untreated plants. The expression levels of differentially-expressed genes involved in pathogen-associated molecular pattern-triggered immunity (PTI), oxidation resistance, and water-deficit stress tolerance were upregulated in the Si-treated plants. Multiple hormone-related genes were differentially expressed in the Si-treated plants. Si-mediated resistance involves mechanisms other than SA- and JA/ET-mediated stress responses. We propose that Si-mediated tomato resistance to R. solanacearum is associated with activated PTI-related responses and enhanced disease resistance and tolerance via several signaling pathways. Such pathways are mediated by multiple hormones (e.g., SA, JA, ET, and auxin), leading to diminished adverse effects (e.g., senescence, water-deficit, salinity and oxidative stress) normally caused by R. solanacearum infection. This finding will provide an important basis to further characterize the role of Si in enhancing plant resistance against biotic stress.

scholarly journals Monitoring Arsenic Species Content in Seaweeds Produced off the Southern Coast of Korea and Its Risk Assessment

Environments ◽  
2020 ◽  
Vol 7 (9) ◽  
pp. 68
Author(s):  
Min-hyuk Kim ◽  
Junseob Kim ◽  
Chang-Hyun Noh ◽  
Seogyeong Choi ◽  
Yong-Sung Joo ◽  
...  
Keyword(s):  
Risk Assessment ◽  
South Korea ◽  
Arsenic Speciation ◽  
Arsenic Exposure ◽  
Inorganic Arsenic ◽  
Speciation Analysis ◽  
Arsenic Species ◽  
Dimethylarsinic Acid ◽  
Concentration Data ◽  
Seaweed Species

Seaweed, a popular seafood in South Korea, has abundant dietary fiber and minerals. The toxicity of arsenic compounds is known to be related to their chemical speciation, and inorganic arsenic (iAs) is more detrimental than other species. Due to the different toxicities of the various chemical forms, speciation analysis is important for evaluating arsenic exposure. In this study, total arsenic (tAs) and six arsenic species (arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, and arsenocholine) were analyzed in 180 seaweed samples. Although there were differences between seaweed species, the concentration of tAs was detected at levels ranging from 1 to 100 µg/g, and the distribution of six arsenic species differed depending on the seaweed species. No correlation between the concentration of iAs and tAs was found in most seaweed species. Through statistical clustering, hijiki and gulfweed were seen to be the seaweeds with the highest ratios of iAs to tAs. Using the iAs concentration data from the arsenic speciation analysis, a risk assessment of seaweed intake in South Korea was conducted. The margin of exposure values showed no meaningful risk for the general population, but low levels of risk were identified for seaweed consumers, with high intakes of gulfweed and hijiki.

scholarly journals Groundwater Irrigation and Arsenic Speciation in Rice in Cambodia

2018 ◽  
Vol 8 (19) ◽  
Author(s):  
Tom Murphy ◽  
Kongkea Phan ◽  
Emmanuel Yumvihoze ◽  
Kim Irvine ◽  
Ken Wilson ◽  
...  
Keyword(s):  
Arsenic Speciation ◽  
Arsenic Concentration ◽  
Arsenic Exposure ◽  
Inorganic Arsenic ◽  
Arsenic Species ◽  
Dimethylarsinic Acid ◽  
Total Arsenic ◽  
Groundwater Irrigation ◽  
Financial Interests ◽  
Rice Consumption

Background. Arsenic bioaccumulation in rice is a global concern affecting food security and public health. Objective. The present study examined arsenic species in rice in Cambodia to characterize health risks with rice consumption and to clarify uncertainties with Codex guidelines. Methods. The present study collected 61 well water samples, 105 rice samples, 70 soil samples, and conducted interviews with 44 families in Preak Russey near the Bassac River and Kandal Province along the Mekong River in Cambodia. Analyses of metals, total arsenic and arsenic species were conducted in laboratories in Canada, Cambodia and Singapore. Results. Unlike in Bangladesh, rice with the highest total arsenic concentrations in Cambodia contains mostly organic arsenic, dimethylarsinic acid (DMA), which is unregulated and much less toxic than inorganic arsenic. The present study found that storing surface runoff in ditches prior to irrigation can significantly reduce the arsenic concentration in rice. It is possible to remove > 95% of arsenic from groundwater prior to irrigation with natural reactions. Conclusions. The provision of high quality drinking water in 2015 to Preak Russey removed about 95% of the dietary inorganic arsenic exposure. The extremes in arsenic toxicity that are still obvious in these farmers should become less common. Rice from the site with the highest documented levels of arsenic in soils and water in Cambodia passes current Codex guidelines for arsenic. Informed Consent. Obtained Competing Interests. The authors declare no competing financial interests.

Role of Artesunate in Potentiation of β-lactam Against Methicillin Resistant Staphylococcus aureus (MRSA) Isolated from Bovine Mastitis and its Histopathology Impact In-Vivo Study

2020 ◽  
Keyword(s):  
Clavulanic Acid ◽  
Resistance Mechanism ◽  
Bovine Mastitis ◽  
Lethal Challenge ◽  
Experimental Procedure ◽  
Appropriate Treatment ◽  
Amoxicillin Clavulanic Acid ◽  
Mrsa Infection

This article discusses the augmenting influence of Artesunate (ART) in combination with β-lactams (amoxicillin/clavulanic acid) antibiotic in sepsis mice models infected by a lethal challenge dose of live coagulase positive enterotoxigenic (Sec) MRSA that was isolated from a case of chronic bovine mastitis. The main goal is to find an appropriate treatment to overcome resistance mechanism of MRSA towards β-lactams antibiotic. Fifty healthy adult Swiss mice divided into 5 equal groups were used in the experimental procedure. The infected group that treated with both ART and β-lactams (amoxicillin/clavulanic acid) antibiotic revealed complete inhibition of MRSA count with complete normal macroscopic and histopathological features. We suggest that ART can potentiate the antibacterial action of β-lactams (amoxicillin/Clavulanic) acid against MRSA infection. The combination of ART and antibiotic can overcome MRSA resistance mechanism and so could be considered a novel candidate to overcome mastitis and/or sepsis caused by MRSA.

scholarly journals The Role of Aquaporin Overexpression in the Modulation of Transcription of Heavy Metal Transporters under Cadmium Treatment in Poplar

Plants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 54
Author(s):  
Andrea Neri ◽  
Silvia Traversari ◽  
Andrea Andreucci ◽  
Alessandra Francini ◽  
Luca Sebastiani
Keyword(s):  
Heavy Metal ◽  
Transcriptional Response ◽  
Metal Transporters ◽  
Metal Transporter ◽  
Cadmium Treatment ◽  
Tolerance To Cadmium ◽  
Different Response ◽  
Cd Translocation ◽  
Hydroponic Conditions

Populus alba ‘Villafranca’ clone is well-known for its tolerance to cadmium (Cd). To determine the mechanisms of Cd tolerance of this species, wild-type (wt) plants were compared with transgenic plants over-expressing an aquaporin (aqua1, GenBank GQ918138). Plants were maintained in hydroponic conditions with Hoagland’s solution and treated with 10 µM of Cd, renewed every 5 d. The transcription levels of heavy metal transporter genes (PaHMA2, PaNRAMP1.3, PaNRAMP2, PaNRAMP3.1, PaNRAMP3.2, PaABCC9, and PaABCC13) were analyzed at 1, 7, and 60 d of treatment. Cd application did not induce visible toxicity symptoms in wt and aqua1 plants even after 2 months of treatment confirming the high tolerance of this poplar species to Cd. Most of the analyzed genes showed in wt plants a quick response in transcription at 1 d of treatment and an adaptation at 60 d. On the contrary, a lower transcriptional response was observed in aqua1 plants in concomitance with a higher Cd concentration in medial leaves. Moreover, PaHMA2 showed at 1 d an opposite trend within organs since it was up-regulated in root and stem of wt plants and in leaves of aqua1 plants. In summary, aqua1 overexpression in poplar improved Cd translocation suggesting a lower Cd sensitivity of aqua1 plants. This different response might be due to a different transcription of PaNRAMP3 genes that were more transcribed in wt line because of the importance of this gene in Cd compartmentalization.

scholarly journals Physiological and interactomic analysis reveals versatile functions of Arabidopsis 14-3-3 quadruple mutants in response to Fe deficiency

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jing Gao ◽  
Paula J. M. van Kleeff ◽  
Ka Wan Li ◽  
Albertus H. de Boer
Keyword(s):  
Iron Acquisition ◽  
Tca Cycle ◽  
Utilization Efficiency ◽  
Fe Deficiency ◽  
Transcriptional Level ◽  
Functional Aspects ◽  
Clear Explanation ◽  
Physiological Analysis ◽  
Proper Operation

AbstractTo date, few phenotypes have been described for Arabidopsis 14-3-3 mutants or the phenotypes showing the role of 14-3-3 in plant responding to abiotic stress. Although one member of the 14-3-3 protein family (14-3-3 omicron) was shown to be involved in the proper operation of Fe acquisition mechanisms at physiological and gene expression levels in Arabidopsis thaliana, it remains to be explored whether other members play a role in regulating iron acquisition. To more directly and effectively observe whether members of 14-3-3 non-epsilon group have a function in Fe-deficiency adaptation, three higher order quadruple KOs, kappa/lambda/phi/chi (klpc), kappa/lambda/upsilon/nu(klun), and upsilon/nu/phi/chi (unpc) were generated and studied for physiological analysis in this study. The analysis of iron-utilization efficiency, root phenotyping, and transcriptional level of Fe-responsive genes suggested that the mutant with kl background showed different phenotypes from Wt when plants suffered Fe starved, while these phenotypes were absent in the unpc mutant. Moreover, the absence of the four 14-3-3 isoforms in the klun mutant has a clear impact on the 14-3-3 interactome upon Fe deficiency. Dynamics of 14-3-3-client interactions analysis showed that 27 and 17 proteins differentially interacted with 14-3-3 in Wt and klun roots caused by Fe deficiency, respectively. Many of these Fe responsive proteins have a role in glycolysis, oxidative phosphorylation and TCA cycle, the FoF1-synthase and in the cysteine/methionine synthesis. A clear explanation for the observed phenotypes awaits a more detailed analysis of the functional aspects of 14-3-3 binding to the target proteins identified in this study.

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