Lateral Gene Transfer Dynamics in the Ancient Bacterial Genus Streptomyces.

PubMed

McDonald, Bradon R; Currie, Cameron R

2017-06-06

Lateral gene transfer (LGT) profoundly shapes the evolution of bacterial lineages. LGT across disparate phylogenetic groups and genome content diversity between related organisms suggest a model of bacterial evolution that views LGT as rampant and promiscuous. It has even driven the argument that species concepts and tree-based phylogenetics cannot be applied to bacteria. Here, we show that acquisition and retention of genes through LGT are surprisingly rare in the ubiquitous and biomedically important bacterial genus Streptomyces Using a molecular clock, we estimate that the Streptomyces bacteria are ~380 million years old, indicating that this bacterial genus is as ancient as land vertebrates. Calibrating LGT rate to this geologic time span, we find that on average only 10 genes per million years were acquired and subsequently maintained. Over that same time span, Streptomyces accumulated thousands of point mutations. By explicitly incorporating evolutionary timescale into our analyses, we provide a dramatically different view on the dynamics of LGT and its impact on bacterial evolution. IMPORTANCE Tree-based phylogenetics and the use of species as units of diversity lie at the foundation of modern biology. In bacteria, these pillars of evolutionary theory have been called into question due to the observation of thousands of lateral gene transfer (LGT) events within and between lineages. Here, we show that acquisition and retention of genes through LGT are exceedingly rare in the bacterial genus Streptomyces , with merely one gene acquired in Streptomyces lineages every 100,000 years. These findings stand in contrast to the current assumption of rampant genetic exchange, which has become the dominant hypothesis used to explain bacterial diversity. Our results support a more nuanced understanding of genetic exchange, with LGT impacting evolution over short timescales but playing a significant role over long timescales. Deeper understanding of LGT provides new

Bacterial reference genes for gene expression studies by RT-qPCR: survey and analysis.

PubMed

Rocha, Danilo J P; Santos, Carolina S; Pacheco, Luis G C

2015-09-01

The appropriate choice of reference genes is essential for accurate normalization of gene expression data obtained by the method of reverse transcription quantitative real-time PCR (RT-qPCR). In 2009, a guideline called the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) highlighted the importance of the selection and validation of more than one suitable reference gene for obtaining reliable RT-qPCR results. Herein, we searched the recent literature in order to identify the bacterial reference genes that have been most commonly validated in gene expression studies by RT-qPCR (in the first 5 years following publication of the MIQE guidelines). Through a combination of different search parameters with the text mining tool MedlineRanker, we identified 145 unique bacterial genes that were recently tested as candidate reference genes. Of these, 45 genes were experimentally validated and, in most of the cases, their expression stabilities were verified using the software tools geNorm and NormFinder. It is noteworthy that only 10 of these reference genes had been validated in two or more of the studies evaluated. An enrichment analysis using Gene Ontology classifications demonstrated that genes belonging to the functional categories of DNA Replication (GO: 0006260) and Transcription (GO: 0006351) rendered a proportionally higher number of validated reference genes. Three genes in the former functional class were also among the top five most stable genes identified through an analysis of gene expression data obtained from the Pathosystems Resource Integration Center. These results may provide a guideline for the initial selection of candidate reference genes for RT-qPCR studies in several different bacterial species.

Genome-wide identification of bacterial plant colonization genes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cole, Benjamin J.; Feltcher, Meghan E.; Waters, Robert J.

Diverse soil-resident bacteria can contribute to plant growth and health, but the molecular mechanisms enabling them to effectively colonize their plant hosts remain poorly understood. We used randomly barcoded transposon mutagenesis sequencing (RB-TnSeq) in Pseudomonas simiae, a model root-colonizing bacterium, to establish a genome-wide map of bacterial genes required for colonization of the Arabidopsis thaliana root system. We identified 115 genes (2% of all P. simiae genes) with functions that are required for maximal competitive colonization of the root system. Among the genes we identified were some with obvious colonization-related roles in motility and carbon metabolism, as well as 44more » other genes that had no or vague functional predictions. Independent validation assays of individual genes confirmed colonization functions for 20 of 22 (91%) cases tested. To further characterize genes identified by our screen, we compared the functional contributions of P. simiae genes to growth in 90 distinct in vitro conditions by RB-TnSeq, highlighting specific metabolic functions associated with root colonization genes. Here, our analysis of bacterial genes by sequence-driven saturation mutagenesis revealed a genome-wide map of the genetic determinants of plant root colonization and offers a starting point for targeted improvement of the colonization capabilities of plant-beneficial microbes.« less

Genome-wide identification of bacterial plant colonization genes

DOE PAGES

Cole, Benjamin J.; Feltcher, Meghan E.; Waters, Robert J.; ...

2017-09-22

Diverse soil-resident bacteria can contribute to plant growth and health, but the molecular mechanisms enabling them to effectively colonize their plant hosts remain poorly understood. We used randomly barcoded transposon mutagenesis sequencing (RB-TnSeq) in Pseudomonas simiae, a model root-colonizing bacterium, to establish a genome-wide map of bacterial genes required for colonization of the Arabidopsis thaliana root system. We identified 115 genes (2% of all P. simiae genes) with functions that are required for maximal competitive colonization of the root system. Among the genes we identified were some with obvious colonization-related roles in motility and carbon metabolism, as well as 44more » other genes that had no or vague functional predictions. Independent validation assays of individual genes confirmed colonization functions for 20 of 22 (91%) cases tested. To further characterize genes identified by our screen, we compared the functional contributions of P. simiae genes to growth in 90 distinct in vitro conditions by RB-TnSeq, highlighting specific metabolic functions associated with root colonization genes. Here, our analysis of bacterial genes by sequence-driven saturation mutagenesis revealed a genome-wide map of the genetic determinants of plant root colonization and offers a starting point for targeted improvement of the colonization capabilities of plant-beneficial microbes.« less

Transcriptome-Level Signatures in Gene Expression and Gene Expression Variability during Bacterial Adaptive Evolution.

PubMed

Erickson, Keesha E; Otoupal, Peter B; Chatterjee, Anushree

2017-01-01

Antibiotic-resistant bacteria are an increasingly serious public health concern, as strains emerge that demonstrate resistance to almost all available treatments. One factor that contributes to the crisis is the adaptive ability of bacteria, which exhibit remarkable phenotypic and gene expression heterogeneity in order to gain a survival advantage in damaging environments. This high degree of variability in gene expression across biological populations makes it a challenging task to identify key regulators of bacterial adaptation. Here, we research the regulation of adaptive resistance by investigating transcriptome profiles of Escherichia coli upon adaptation to disparate toxins, including antibiotics and biofuels. We locate potential target genes via conventional gene expression analysis as well as using a new analysis technique examining differential gene expression variability. By investigating trends across the diverse adaptation conditions, we identify a focused set of genes with conserved behavior, including those involved in cell motility, metabolism, membrane structure, and transport, and several genes of unknown function. To validate the biological relevance of the observed changes, we synthetically perturb gene expression using clustered regularly interspaced short palindromic repeat (CRISPR)-dCas9. Manipulation of select genes in combination with antibiotic treatment promotes adaptive resistance as demonstrated by an increased degree of antibiotic tolerance and heterogeneity in MICs. We study the mechanisms by which identified genes influence adaptation and find that select differentially variable genes have the potential to impact metabolic rates, mutation rates, and motility. Overall, this work provides evidence for a complex nongenetic response, encompassing shifts in gene expression and gene expression variability, which underlies adaptive resistance. IMPORTANCE Even initially sensitive bacteria can rapidly thwart antibiotic treatment through stress

Genes and Gut Bacteria Involved in Luminal Butyrate Reduction Caused by Diet and Loperamide.

PubMed

Hwang, Nakwon; Eom, Taekil; Gupta, Sachin K; Jeong, Seong-Yeop; Jeong, Do-Youn; Kim, Yong Sung; Lee, Ji-Hoon; Sadowsky, Michael J; Unno, Tatsuya

2017-11-28

Unbalanced dietary habits and gut dysmotility are causative factors in metabolic and functional gut disorders, including obesity, diabetes, and constipation. Reduction in luminal butyrate synthesis is known to be associated with gut dysbioses, and studies have suggested that restoring butyrate formation in the colon may improve gut health. In contrast, shifts in different types of gut microbiota may inhibit luminal butyrate synthesis, requiring different treatments to restore colonic bacterial butyrate synthesis. We investigated the influence of high-fat diets (HFD) and low-fiber diets (LFD), and loperamide (LPM) administration, on key bacteria and genes involved in reduction of butyrate synthesis in mice. MiSeq-based microbiota analysis and HiSeq-based differential gene analysis indicated that different types of bacteria and genes were involved in butyrate metabolism in each treatment. Dietary modulation depleted butyrate kinase and phosphate butyryl transferase by decreasing members of the Bacteroidales and Parabacteroides . The HFD also depleted genes involved in succinate synthesis by decreasing Lactobacillus . The LFD and LPM treatments depleted genes involved in crotonoyl-CoA synthesis by decreasing Roseburia and Oscilllibacter . Taken together, our results suggest that different types of bacteria and genes were involved in gut dysbiosis, and that selected treatments may be needed depending on the cause of gut dysfunction.

A maize resistance gene functions against bacterial streak disease in rice.

PubMed

Zhao, Bingyu; Lin, Xinghua; Poland, Jesse; Trick, Harold; Leach, Jan; Hulbert, Scot

2005-10-25

Although cereal crops all belong to the grass family (Poacea), most of their diseases are specific to a particular species. Thus, a given cereal species is typically resistant to diseases of other grasses, and this nonhost resistance is generally stable. To determine the feasibility of transferring nonhost resistance genes (R genes) between distantly related grasses to control specific diseases, we identified a maize R gene that recognizes a rice pathogen, Xanthomonas oryzae pv. oryzicola, which causes bacterial streak disease. Bacterial streak is an important disease of rice in Asia, and no simply inherited sources of resistance have been identified in rice. Although X. o. pv. oryzicola does not cause disease on maize, we identified a maize gene, Rxo1, that conditions a resistance reaction to a diverse collection of pathogen strains. Surprisingly, Rxo1 also controls resistance to the unrelated pathogen Burkholderia andropogonis, which causes bacterial stripe of sorghum and maize. The same gene thus controls resistance reactions to both pathogens and nonpathogens of maize. Rxo1 has a nucleotide-binding site-leucine-rich repeat structure, similar to many previously identified R genes. Most importantly, Rxo1 functions after transfer as a transgene to rice, demonstrating the feasibility of nonhost R gene transfer between cereals and providing a valuable tool for controlling bacterial streak disease.

Evaluating bacterial gene-finding HMM structures as probabilistic logic programs.

PubMed

Mørk, Søren; Holmes, Ian

2012-03-01

Probabilistic logic programming offers a powerful way to describe and evaluate structured statistical models. To investigate the practicality of probabilistic logic programming for structure learning in bioinformatics, we undertook a simplified bacterial gene-finding benchmark in PRISM, a probabilistic dialect of Prolog. We evaluate Hidden Markov Model structures for bacterial protein-coding gene potential, including a simple null model structure, three structures based on existing bacterial gene finders and two novel model structures. We test standard versions as well as ADPH length modeling and three-state versions of the five model structures. The models are all represented as probabilistic logic programs and evaluated using the PRISM machine learning system in terms of statistical information criteria and gene-finding prediction accuracy, in two bacterial genomes. Neither of our implementations of the two currently most used model structures are best performing in terms of statistical information criteria or prediction performances, suggesting that better-fitting models might be achievable. The source code of all PRISM models, data and additional scripts are freely available for download at: http://github.com/somork/codonhmm. Supplementary data are available at Bioinformatics online.

Determination of the Core of a Minimal Bacterial Gene Set†

PubMed Central

Gil, Rosario; Silva, Francisco J.; Peretó, Juli; Moya, Andrés

2004-01-01

The availability of a large number of complete genome sequences raises the question of how many genes are essential for cellular life. Trying to reconstruct the core of the protein-coding gene set for a hypothetical minimal bacterial cell, we have performed a computational comparative analysis of eight bacterial genomes. Six of the analyzed genomes are very small due to a dramatic genome size reduction process, while the other two, corresponding to free-living relatives, are larger. The available data from several systematic experimental approaches to define all the essential genes in some completely sequenced bacterial genomes were also considered, and a reconstruction of a minimal metabolic machinery necessary to sustain life was carried out. The proposed minimal genome contains 206 protein-coding genes with all the genetic information necessary for self-maintenance and reproduction in the presence of a full complement of essential nutrients and in the absence of environmental stress. The main features of such a minimal gene set, as well as the metabolic functions that must be present in the hypothetical minimal cell, are discussed. PMID:15353568

A maize resistance gene functions against bacterial streak disease in rice

PubMed Central

Zhao, Bingyu; Lin, Xinghua; Poland, Jesse; Trick, Harold; Leach, Jan; Hulbert, Scot

2005-01-01

Although cereal crops all belong to the grass family (Poacea), most of their diseases are specific to a particular species. Thus, a given cereal species is typically resistant to diseases of other grasses, and this nonhost resistance is generally stable. To determine the feasibility of transferring nonhost resistance genes (R genes) between distantly related grasses to control specific diseases, we identified a maize R gene that recognizes a rice pathogen, Xanthomonas oryzae pv. oryzicola, which causes bacterial streak disease. Bacterial streak is an important disease of rice in Asia, and no simply inherited sources of resistance have been identified in rice. Although X. o. pv. oryzicola does not cause disease on maize, we identified a maize gene, Rxo1, that conditions a resistance reaction to a diverse collection of pathogen strains. Surprisingly, Rxo1 also controls resistance to the unrelated pathogen Burkholderia andropogonis, which causes bacterial stripe of sorghum and maize. The same gene thus controls resistance reactions to both pathogens and nonpathogens of maize. Rxo1 has a nucleotide-binding site-leucine-rich repeat structure, similar to many previously identified R genes. Most importantly, Rxo1 functions after transfer as a transgene to rice, demonstrating the feasibility of nonhost R gene transfer between cereals and providing a valuable tool for controlling bacterial streak disease. PMID:16230639

Analysis for the presence of determinants involved in the transport of mercury across bacterial membrane from polluted water bodies of India

PubMed Central

Jan, Arif Tasleem; Azam, Mudsser; Choi, Inho; Ali, Arif; Haq, Qazi Mohd. Rizwanul

2016-01-01

Mercury, which is ubiquitous and recalcitrant to biodegradation processes, threatens human health by escaping to the environment via various natural and anthropogenic activities. Non-biodegradability of mercury pollutants has necessitated the development and implementation of economic alternatives with promising potential to remove metals from the environment. Enhancement of microbial based remediation strategies through genetic engineering approaches provides one such alternative with a promising future. In this study, bacterial isolates inhabiting polluted sites were screened for tolerance to varying concentrations of mercuric chloride. Following identification, several Pseudomonas and Klebsiella species were found to exhibit the highest tolerance to both organic and inorganic mercury. Screened bacterial isolates were examined for their genetic make-up in terms of the presence of genes (merP and merT) involved in the transport of mercury across the membrane either alone or in combination to deal with the toxic mercury. Gene sequence analysis revealed that the merP gene showed 86–99% homology, while the merT gene showed >98% homology with previously reported sequences. By exploring the genes involved in imparting metal resistance to bacteria, this study will serve to highlight the credentials that are particularly advantageous for their practical application to remediation of mercury from the environment. PMID:26887227

Genome engineering and gene expression control for bacterial strain development.

PubMed

Song, Chan Woo; Lee, Joungmin; Lee, Sang Yup

2015-01-01

In recent years, a number of techniques and tools have been developed for genome engineering and gene expression control to achieve desired phenotypes of various bacteria. Here we review and discuss the recent advances in bacterial genome manipulation and gene expression control techniques, and their actual uses with accompanying examples. Genome engineering has been commonly performed based on homologous recombination. During such genome manipulation, the counterselection systems employing SacB or nucleases have mainly been used for the efficient selection of desired engineered strains. The recombineering technology enables simple and more rapid manipulation of the bacterial genome. The group II intron-mediated genome engineering technology is another option for some bacteria that are difficult to be engineered by homologous recombination. Due to the increasing demands on high-throughput screening of bacterial strains having the desired phenotypes, several multiplex genome engineering techniques have recently been developed and validated in some bacteria. Another approach to achieve desired bacterial phenotypes is the repression of target gene expression without the modification of genome sequences. This can be performed by expressing antisense RNA, small regulatory RNA, or CRISPR RNA to repress target gene expression at the transcriptional or translational level. All of these techniques allow efficient and rapid development and screening of bacterial strains having desired phenotypes, and more advanced techniques are expected to be seen. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Can dead bacterial cells be defined and are genes expressed after cell death?

PubMed

Trevors, J T

2012-07-01

There is a paucity of knowledge on gene expression in dead bacterial cells. Why would this knowledge be useful? The cells are dead. However, the time duration of gene expression following cell death is often unknown, and possibly in the order of minutes. In addition, it is a challenge to determine if bacterial cells are dead, or viable but non-culturable (VBNC), and what is an agreed upon correct definition of dead bacteria. Cells in the bacterial population or community may die at different rates or times and this complicates both the viability and gene expression analysis. In this article, the definition of dead bacterial cells is discussed and its significance in continued gene expression in cells following death. The definition of living and dead has implications for possible, completely, synthetic bacterial cells that may be capable of growth and division. Copyright © 2012 Elsevier B.V. All rights reserved.

Transcriptome analysis of WRKY gene family in Oryza officinalis Wall ex Watt and WRKY genes involved in responses to Xanthomonas oryzae pv. oryzae stress

PubMed Central

Jiang, Chunmiao; Shen, Qingxi J.; Wang, Bo; He, Bin; Xiao, Suqin; Chen, Ling; Yu, Tengqiong; Ke, Xue; Zhong, Qiaofang; Fu, Jian; Chen, Yue; Wang, Lingxian; Yin, Fuyou; Zhang, Dunyu; Ghidan, Walid; Huang, Xingqi; Cheng, Zaiquan

2017-01-01

Oryza officinalis Wall ex Watt, a very important and special wild rice species, shows abundant genetic diversity and disease resistance features, especially high resistance to bacterial blight. The molecular mechanisms of bacterial blight resistance in O. officinalis have not yet been elucidated. The WRKY transcription factor family is one of the largest gene families involved in plant growth, development and stress response. However, little is known about the numbers, structure, molecular phylogenetics, and expression of the WRKY genes under Xanthomonas oryzae pv. oryzae (Xoo) stress in O. officinalis due to lacking of O. officinalis genome. Therefore, based on the RNA-sequencing data of O. officinalis, we performed a comprehensive study of WRKY genes in O. officinalis and identified 89 OoWRKY genes. Then 89 OoWRKY genes were classified into three groups based on the WRKY domains and zinc finger motifs. Phylogenetic analysis strongly supported that the evolution of OoWRKY genes were consistent with previous studies of WRKYs, and subgroup IIc OoWRKY genes were the original ancestors of some group II and group III OoWRKYs. Among the 89 OoWRKY genes, eight OoWRKYs displayed significantly different expression (>2-fold, p<0.01) in the O. officinalis transcriptome under Xoo strains PXO99 and C5 stress 48 h, suggesting these genes might play important role in PXO99 and C5 stress responses in O. officinalis. QRT-PCR analysis and confirmation of eight OoWRKYs expression patterns revealed that they responded strongly to PXO99 and C5 stress 24 h, 48 h, and 72 h, and the trends of these genes displaying marked changes were consistent with the 48 h RNA-sequencing data, demonstrated these genes played important roles in response to biotic stress and might even involved in the bacterial blight resistance. Tissue expression profiles of eight OoWRKY genes revealed that they were highly expressed in root, stem, leaf, and flower, especially in leaf (except OoWRKY71), suggesting

Transcriptome analysis of WRKY gene family in Oryza officinalis Wall ex Watt and WRKY genes involved in responses to Xanthomonas oryzae pv. oryzae stress.

PubMed

Jiang, Chunmiao; Shen, Qingxi J; Wang, Bo; He, Bin; Xiao, Suqin; Chen, Ling; Yu, Tengqiong; Ke, Xue; Zhong, Qiaofang; Fu, Jian; Chen, Yue; Wang, Lingxian; Yin, Fuyou; Zhang, Dunyu; Ghidan, Walid; Huang, Xingqi; Cheng, Zaiquan

2017-01-01

Oryza officinalis Wall ex Watt, a very important and special wild rice species, shows abundant genetic diversity and disease resistance features, especially high resistance to bacterial blight. The molecular mechanisms of bacterial blight resistance in O. officinalis have not yet been elucidated. The WRKY transcription factor family is one of the largest gene families involved in plant growth, development and stress response. However, little is known about the numbers, structure, molecular phylogenetics, and expression of the WRKY genes under Xanthomonas oryzae pv. oryzae (Xoo) stress in O. officinalis due to lacking of O. officinalis genome. Therefore, based on the RNA-sequencing data of O. officinalis, we performed a comprehensive study of WRKY genes in O. officinalis and identified 89 OoWRKY genes. Then 89 OoWRKY genes were classified into three groups based on the WRKY domains and zinc finger motifs. Phylogenetic analysis strongly supported that the evolution of OoWRKY genes were consistent with previous studies of WRKYs, and subgroup IIc OoWRKY genes were the original ancestors of some group II and group III OoWRKYs. Among the 89 OoWRKY genes, eight OoWRKYs displayed significantly different expression (>2-fold, p<0.01) in the O. officinalis transcriptome under Xoo strains PXO99 and C5 stress 48 h, suggesting these genes might play important role in PXO99 and C5 stress responses in O. officinalis. QRT-PCR analysis and confirmation of eight OoWRKYs expression patterns revealed that they responded strongly to PXO99 and C5 stress 24 h, 48 h, and 72 h, and the trends of these genes displaying marked changes were consistent with the 48 h RNA-sequencing data, demonstrated these genes played important roles in response to biotic stress and might even involved in the bacterial blight resistance. Tissue expression profiles of eight OoWRKY genes revealed that they were highly expressed in root, stem, leaf, and flower, especially in leaf (except OoWRKY71), suggesting

Bacterial α2-macroglobulins: colonization factors acquired by horizontal gene transfer from the metazoan genome?

PubMed Central

Budd, Aidan; Blandin, Stephanie; Levashina, Elena A; Gibson, Toby J

2004-01-01

Background Invasive bacteria are known to have captured and adapted eukaryotic host genes. They also readily acquire colonizing genes from other bacteria by horizontal gene transfer. Closely related species such as Helicobacter pylori and Helicobacter hepaticus, which exploit different host tissues, share almost none of their colonization genes. The protease inhibitor α2-macroglobulin provides a major metazoan defense against invasive bacteria, trapping attacking proteases required by parasites for successful invasion. Results Database searches with metazoan α2-macroglobulin sequences revealed homologous sequences in bacterial proteomes. The bacterial α2-macroglobulin phylogenetic distribution is patchy and violates the vertical descent model. Bacterial α2-macroglobulin genes are found in diverse clades, including purple bacteria (proteobacteria), fusobacteria, spirochetes, bacteroidetes, deinococcids, cyanobacteria, planctomycetes and thermotogae. Most bacterial species with bacterial α2-macroglobulin genes exploit higher eukaryotes (multicellular plants and animals) as hosts. Both pathogenically invasive and saprophytically colonizing species possess bacterial α2-macroglobulins, indicating that bacterial α2-macroglobulin is a colonization rather than a virulence factor. Conclusions Metazoan α2-macroglobulins inhibit proteases of pathogens. The bacterial homologs may function in reverse to block host antimicrobial defenses. α2-macroglobulin was probably acquired one or more times from metazoan hosts and has then spread widely through other colonizing bacterial species by more than 10 independent horizontal gene transfers. yfhM-like bacterial α2-macroglobulin genes are often found tightly linked with pbpC, encoding an atypical peptidoglycan transglycosylase, PBP1C, that does not function in vegetative peptidoglycan synthesis. We suggest that YfhM and PBP1C are coupled together as a periplasmic defense and repair system. Bacterial α2-macroglobulins might

Evaluating the consistency of gene sets used in the analysis of bacterial gene expression data.

PubMed

Tintle, Nathan L; Sitarik, Alexandra; Boerema, Benjamin; Young, Kylie; Best, Aaron A; Dejongh, Matthew

2012-08-08

Statistical analyses of whole genome expression data require functional information about genes in order to yield meaningful biological conclusions. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) are common sources of functionally grouped gene sets. For bacteria, the SEED and MicrobesOnline provide alternative, complementary sources of gene sets. To date, no comprehensive evaluation of the data obtained from these resources has been performed. We define a series of gene set consistency metrics directly related to the most common classes of statistical analyses for gene expression data, and then perform a comprehensive analysis of 3581 Affymetrix® gene expression arrays across 17 diverse bacteria. We find that gene sets obtained from GO and KEGG demonstrate lower consistency than those obtained from the SEED and MicrobesOnline, regardless of gene set size. Despite the widespread use of GO and KEGG gene sets in bacterial gene expression data analysis, the SEED and MicrobesOnline provide more consistent sets for a wide variety of statistical analyses. Increased use of the SEED and MicrobesOnline gene sets in the analysis of bacterial gene expression data may improve statistical power and utility of expression data.

Metabolic pathways of Pseudomonas aeruginosa involved in competition with respiratory bacterial pathogens

PubMed Central

Beaume, Marie; Köhler, Thilo; Fontana, Thierry; Tognon, Mikael; Renzoni, Adriana; van Delden, Christian

2015-01-01

Background: Chronic airway infection by Pseudomonas aeruginosa considerably contributes to lung tissue destruction and impairment of pulmonary function in cystic-fibrosis (CF) patients. Complex interplays between P. aeruginosa and other co-colonizing pathogens including Staphylococcus aureus, Burkholderia sp., and Klebsiella pneumoniae may be crucial for pathogenesis and disease progression. Methods: We generated a library of PA14 transposon insertion mutants to identify P. aeruginosa genes required for exploitative and direct competitions with S. aureus, Burkholderia cenocepacia, and K. pneumoniae. Results: Whereas wild-type PA14 inhibited S. aureus growth, two transposon insertions located in pqsC and carB, resulted in reduced growth inhibition. PqsC is involved in the synthesis of 4-hydroxy-2-alkylquinolines (HAQs), a family of molecules having antibacterial properties, while carB is a key gene in pyrimidine biosynthesis. The carB mutant was also unable to grow in the presence of B. cepacia and K. pneumoniae but not Escherichia coli and S. epidermidis. We further identified a transposon insertion in purF, encoding a key enzyme of purine metabolism. This mutant displayed a severe growth deficiency in the presence of Gram-negative but not of Gram-positive bacteria. We identified a beneficial interaction in a bioA transposon mutant, unable to grow on rich medium. This growth defect could be restored either by addition of biotin or by co-culturing the mutant in the presence of K. pneumoniae or E. coli. Conclusion: Complex interactions take place between the various bacterial species colonizing CF-lungs. This work identified both detrimental and beneficial interactions occurring between P. aeruginosa and three other respiratory pathogens involving several major metabolic pathways. Manipulating these pathways could be used to interfere with bacterial interactions and influence the colonization by respiratory pathogens. PMID:25954256

Bacterial evolution through the selective loss of beneficial Genes. Trade-offs in expression involving two loci.

PubMed Central

Zinser, Erik R; Schneider, Dominique; Blot, Michel; Kolter, Roberto

2003-01-01

The loss of preexisting genes or gene activities during evolution is a major mechanism of ecological specialization. Evolutionary processes that can account for gene loss or inactivation have so far been restricted to one of two mechanisms: direct selection for the loss of gene activities that are disadvantageous under the conditions of selection (i.e., antagonistic pleiotropy) and selection-independent genetic drift of neutral (or nearly neutral) mutations (i.e., mutation accumulation). In this study we demonstrate with an evolved strain of Escherichia coli that a third, distinct mechanism exists by which gene activities can be lost. This selection-dependent mechanism involves the expropriation of one gene's upstream regulatory element by a second gene via a homologous recombination event. Resulting from this genetic exchange is the activation of the second gene and a concomitant inactivation of the first gene. This gene-for-gene expression tradeoff provides a net fitness gain, even if the forfeited activity of the first gene can play a positive role in fitness under the conditions of selection. PMID:12930738

Dynamics of Bacterial Gene Regulatory Networks.

PubMed

Shis, David L; Bennett, Matthew R; Igoshin, Oleg A

2018-05-20

The ability of bacterial cells to adjust their gene expression program in response to environmental perturbation is often critical for their survival. Recent experimental advances allowing us to quantitatively record gene expression dynamics in single cells and in populations coupled with mathematical modeling enable mechanistic understanding on how these responses are shaped by the underlying regulatory networks. Here, we review how the combination of local and global factors affect dynamical responses of gene regulatory networks. Our goal is to discuss the general principles that allow extrapolation from a few model bacteria to less understood microbes. We emphasize that, in addition to well-studied effects of network architecture, network dynamics are shaped by global pleiotropic effects and cell physiology.

An Acidic PATHOGENESIS-RELATED1 Gene of Oryza grandiglumis is Involved in Disease Resistance Response Against Bacterial Infection

PubMed Central

Shin, Sang Hyun; Pak, Jung-Hun; Kim, Mi Jin; Kim, Hye Jeong; Oh, Ju Sung; Choi, Hong Kyu; Jung, Ho Won; Chung, Young Soo

2014-01-01

Wild rice, Oryza grandiglumis shows hyper-resistance response to pathogen infection. In order to identify genes necessary for defense response in plants, we have carried out a subtractive hybridization coupled with a cDNA macroarray. An acidic PATHOGENESIS-RELATED1 (PR1) gene of the wild rice is highly identical to the acidic PR1 genes of different plant species. The OgPR1a cDNA has an apparent single open reading frame with a predicted molecular mass 40,621 Da and an isoelectic point of 5.14. Both in silico analysis and a transient expression assay in onion epidermal cells revealed that the OgPR1a protein could be localized in intercellular space in plants. The OgPR1a mRNA was strongly transcribed by the exogenous treatment with ethylene and jasmonic acid as well as protein phosphatase inhibitors. Additionally, ectopic expression of the OgPR1a conferred disease resistance on Arabidopsis to the bacterial and fungal infections. PMID:25289005

Bacterial genes involved in incorporation of nickel into a hydrogenase enzyme.

PubMed Central

Fu, C; Javedan, S; Moshiri, F; Maier, R J

1994-01-01

Nickel is an essential component of all H2-uptake hydrogenases. A fragment of DNA that complements a H2-uptake-deficient but nickel-cured mutant strain (JHK7) of Bradyrhizobium japonicum was isolated and sequenced. This 4.5-kb DNA fragment contains four open reading frames designated as ORF1, hupN, hupO, and hupP, which encode polypeptides with predicted masses of 17, 40, 19, and 63.5 kDa, respectively. The last three open reading frames (hupNOP) are most likely organized as an operon with a putative sigma 54-type promoter. Based on its hydropathy profile, HupN is predicted to be a transmembrane protein. It has 56% identity to the previously described HoxN (high-affinity nickel transport protein) of Alcaligenes eutrophus. A subclone (pJF23) containing the hupNOP genes excluding ORF1 completely complemented (in trans) strain JHK7 for hydrogenase activity in low nickel conditions. pJF26 containing only a functional hupN complemented the hydrogenase activity of mutant strain JHK7 to 30-55% of the wild-type level. Mutant strain JHK70, with a chromosomal deletion in hupP but with an intact hupNO, showed greater activities than pJF26-complemented JHK7 but still had lower activities than the wild type at all nickel levels tested. pJF25, containing the entire hupO and hupP, but without hupN (a portion of hupN was deleted), did not complement hydrogenase activity of mutant strain JHK7. The results suggest that the products of the hupNOP operon are all involved in nickel incorporation/metabolism into the hydrogenase apoprotein. Based on (previous) nickel transport studies of strain JHK7, the hupNOP genes appear not to be involved in nickel transport by whole cells. The deleterious effects on hydrogenase expression are most pronounced by lack of the HupN product. PMID:8197192

Disruption of the M949_RS01915 gene changed the bacterial lipopolysaccharide pattern, pathogenicity and gene expression of Riemerella anatipestifer.

PubMed

Dou, Yafeng; Wang, Xiaolan; Yu, Guijing; Wang, Shaohui; Tian, Mingxing; Qi, Jingjing; Li, Tao; Ding, Chan; Yu, Shengqing

2017-02-06

Riemerella anatipestifer is an important pathogen that causes septicemia anserum exsudativa in ducks. Lipopolysaccharide (LPS) is considered to be a major virulence factor of R. anatipestifer. To identify genes involved in LPS biosynthesis, we screened a library of random Tn4351 transposon mutants using a monoclonal antibody against R. anatipestifer serotype 1 LPS (anti-LPS MAb). A mutant strain RA1067 which lost the reactivity in an indirect ELISA was obtained. Southern blot and sequencing analyses indicated a single Tn4351 was inserted at 116 bp in the M949_RS01915 gene in the RA1067 chromosomal DNA. Silver staining and Western blot analyses indicated that the RA1067 LPS was defected compared to the wild-type strain CH3 LPS. The RA1067 displayed a significant decreased growth rate at the late stage of growth in TSB in comparison with CH3. In addition, RA1067 showed higher susceptibility to complement-dependent killing, more than 360-fold attenuated virulence based on the median lethal dose determination, increased bacterial adhesion and invasion capacities to Vero cells and significantly decreased blood bacterial loads in RA1067 infected ducks, when compared to the CH3. An animal experiment indicated that inactivated RA1067 cells was effective in cross-protecting of the ducks from challenging with R. anatipestifer strains WJ4 (serotype 1), Yb2 (serotype 2) and HXb2 (serotype 10), further confirming the alteration of the RA1067 antigenicity. Moreover, RNA-Seq analysis and real-time PCR verified two up-regulated and three down-regulated genes in RA1067. Our findings demonstrate that the M949_RS01915 gene is associated to bacterial antigenicity, pathogenicity and gene regulation of R. anatipestifer.

Using Bacterial Extract along with Differential Gene Expression in Acropora millepora Larvae to Decouple the Processes of Attachment and Metamorphosis

PubMed Central

Siboni, Nachshon; Abrego, David; Seneca, Francois; Motti, Cherie A.; Andreakis, Nikos; Tebben, Jan; Blackall, Linda L.; Harder, Tilmann

2012-01-01

Biofilms of the bacterium Pseudoalteromonas induce metamorphosis of acroporid coral larvae. The bacterial metabolite tetrabromopyrrole (TBP), isolated from an extract of Pseudoalteromonas sp. associated with the crustose coralline alga (CCA) Neogoniolithon fosliei, induced coral larval metamorphosis (100%) with little or no attachment (0–2%). To better understand the molecular events and mechanisms underpinning the induction of Acropora millepora larval metamorphosis, including cell proliferation, apoptosis, differentiation, migration, adhesion and biomineralisation, two novel coral gene expression assays were implemented. These involved the use of reverse-transcriptase quantitative PCR (RT-qPCR) and employed 47 genes of interest (GOI), selected based on putative roles in the processes of settlement and metamorphosis. Substantial differences in transcriptomic responses of GOI were detected following incubation of A. millepora larvae with a threshold concentration and 10-fold elevated concentration of TBP-containing extracts of Pseudoalteromonas sp. The notable and relatively abrupt changes of the larval body structure during metamorphosis correlated, at the molecular level, with significant differences (p<0.05) in gene expression profiles of 24 GOI, 12 hours post exposure. Fourteen of those GOI also presented differences in expression (p<0.05) following exposure to the threshold concentration of bacterial TBP-containing extract. The specificity of the bacterial TBP-containing extract to induce the metamorphic stage in A. millepora larvae without attachment, using a robust, low cost, accurate, ecologically relevant and highly reproducible RT-qPCR assay, allowed partially decoupling of the transcriptomic processes of attachment and metamorphosis. The bacterial TBP-containing extract provided a unique opportunity to monitor the regulation of genes exclusively involved in the process of metamorphosis, contrasting previous gene expression studies that utilized cues

Interaction of two photoreceptors in the regulation of bacterial photosynthesis genes

PubMed Central

Metz, Sebastian; Haberzettl, Kerstin; Frühwirth, Sebastian; Teich, Kristin; Hasewinkel, Christian; Klug, Gabriele

2012-01-01

The expression of photosynthesis genes in the facultatively photosynthetic bacterium Rhodobacter sphaeroides is controlled by the oxygen tension and by light quantity. Two photoreceptor proteins, AppA and CryB, have been identified in the past, which are involved in this regulation. AppA senses light by its N-terminal BLUF domain, its C-terminal part binds heme and is redox-responsive. Through its interaction to the transcriptional repressor PpsR the AppA photoreceptor controls expression of photosynthesis genes. The cryptochrome-like protein CryB was shown to affect regulation of photosynthesis genes, but the underlying signal chain remained unknown. Here we show that CryB interacts with the C-terminal domain of AppA and modulates the binding of AppA to the transcriptional repressor PpsR in a light-dependent manner. Consequently, binding of the transcription factor PpsR to its DNA target is affected by CryB. In agreement with this, all genes of the PpsR regulon showed altered expression levels in a CryB deletion strain after blue-light illumination. These results elucidate for the first time how a bacterial cryptochrome affects gene expression. PMID:22434878

Interaction of two photoreceptors in the regulation of bacterial photosynthesis genes.

PubMed

Metz, Sebastian; Haberzettl, Kerstin; Frühwirth, Sebastian; Teich, Kristin; Hasewinkel, Christian; Klug, Gabriele

2012-07-01

The expression of photosynthesis genes in the facultatively photosynthetic bacterium Rhodobacter sphaeroides is controlled by the oxygen tension and by light quantity. Two photoreceptor proteins, AppA and CryB, have been identified in the past, which are involved in this regulation. AppA senses light by its N-terminal BLUF domain, its C-terminal part binds heme and is redox-responsive. Through its interaction to the transcriptional repressor PpsR the AppA photoreceptor controls expression of photosynthesis genes. The cryptochrome-like protein CryB was shown to affect regulation of photosynthesis genes, but the underlying signal chain remained unknown. Here we show that CryB interacts with the C-terminal domain of AppA and modulates the binding of AppA to the transcriptional repressor PpsR in a light-dependent manner. Consequently, binding of the transcription factor PpsR to its DNA target is affected by CryB. In agreement with this, all genes of the PpsR regulon showed altered expression levels in a CryB deletion strain after blue-light illumination. These results elucidate for the first time how a bacterial cryptochrome affects gene expression.

RNA-Seq for Bacterial Gene Expression.

PubMed

Poulsen, Line Dahl; Vinther, Jeppe

2018-06-01

RNA sequencing (RNA-seq) has become the preferred method for global quantification of bacterial gene expression. With the continued improvements in sequencing technology and data analysis tools, the most labor-intensive and expensive part of an RNA-seq experiment is the preparation of sequencing libraries, which is also essential for the quality of the data obtained. Here, we present a straightforward and inexpensive basic protocol for preparation of strand-specific RNA-seq libraries from bacterial RNA as well as a computational pipeline for the data analysis of sequencing reads. The protocol is based on the Illumina platform and allows easy multiplexing of samples and the removal of sequencing reads that are PCR duplicates. © 2018 by John Wiley & Sons, Inc. © 2018 John Wiley & Sons, Inc.

The FUN of identifying gene function in bacterial pathogens; insights from Salmonella functional genomics.

PubMed

Hammarlöf, Disa L; Canals, Rocío; Hinton, Jay C D

2013-10-01

The availability of thousands of genome sequences of bacterial pathogens poses a particular challenge because each genome contains hundreds of genes of unknown function (FUN). How can we easily discover which FUN genes encode important virulence factors? One solution is to combine two different functional genomic approaches. First, transcriptomics identifies bacterial FUN genes that show differential expression during the process of mammalian infection. Second, global mutagenesis identifies individual FUN genes that the pathogen requires to cause disease. The intersection of these datasets can reveal a small set of candidate genes most likely to encode novel virulence attributes. We demonstrate this approach with the Salmonella infection model, and propose that a similar strategy could be used for other bacterial pathogens. Copyright © 2013 Elsevier Ltd. All rights reserved.

Deletion of pilA, a Minor Pilin-Like Gene, from Xanthomonas citri subsp. citri Influences Bacterial Physiology and Pathogenesis.

PubMed

Petrocelli, Silvana; Arana, Maite R; Cabrini, Marcela N; Casabuono, Adriana C; Moyano, Laura; Beltramino, Matías; Moreira, Leandro M; Couto, Alicia S; Orellano, Elena G

2016-12-01

Type IV pili (Tfp) are widely distributed adhesins of bacterial surfaces. In plant pathogenic bacteria, Tfp are involved in host colonization and pathogenesis. Xanthomonas citri subsp. citri (Xcc) is the phytopathogen responsible for citrus canker disease. In this work, three Tfp structural genes, fimA, fimA1, and pilA from Xcc were studied. A pilA mutant strain from Xcc (XccΔpilA) was constructed and differences in physiological features, such as motilities, adhesion, and biofilm formation, were observed. A structural study of the purified Tfp fractions from Xcc wild-type and Xcc∆pilA showed that pilins are glycosylated in both strains and that FimA and FimA1 are the main structural components of the pili. Furthermore, smaller lesion symptoms and reduced bacterial growth were produced by Xcc∆pilA in orange plants compared to the wild-type strain. These results indicate that the minor pilin-like gene, pilA, is involved in Tfp performance during the infection process.

sugE: A gene involved in tributyltin (TBT) resistance of Aeromonas molluscorum Av27.

PubMed

Cruz, Andreia; Micaelo, Nuno; Félix, Vitor; Song, Jun-Young; Kitamura, Shin-Ichi; Suzuki, Satoru; Mendo, Sónia

2013-01-01

The mechanism of bacterial resistance to tributyltin (TBT) is still unclear. The results herein presented contribute to clarify that mechanism in the TBT-resistant bacterium Aeromonas molluscorum Av27. We have identified and cloned a new gene that is involved in TBT resistance in this strain. The gene is highly homologous (84%) to the Aeromonas hydrophila-sugE gene belonging to the small multidrug resistance gene family (SMR), which includes genes involved in the transport of lipophilic drugs. In Av27, expression of the Av27-sugE was observed at the early logarithmic growth phase in the presence of a high TBT concentration (500 μM), thus suggesting the contribution of this gene for TBT resistance. E. coli cells transformed with Av27-sugE become resistant to ethidium bromide (EtBr), chloramphenicol (CP) and tetracycline (TE), besides TBT. According to the Moriguchi logP (miLogP) values, EtBr, CP and TE have similar properties and are substrates for the sugE-efflux system. Despite the different miLogP of TBT, E. coli cells transformed with Av27-sugE become resistant to this compound. So it seems that TBT is also a substrate for the SugE protein. The modelling studies performed also support this hypothesis. The data herein presented clearly indicate that sugE is involved in TBT resistance of this bacterium.

Identification and transcriptional profile of multiple genes in the posterior kidney of Nile tilapia at 6h post bacterial infections

USDA-ARS?s Scientific Manuscript database

To understand the molecular mechanisms involved in response of Nile tilapia (Oreochromis niloticus) to bacterial infection, suppression subtractive cDNA hybridization technique was used to identify upregulated genes in the posterior kidney of Nile tilapia at 6h post infection with Aeromonas hydrophi...

Bacterial community and arsenic functional genes diversity in arsenic contaminated soils from different geographic locations

PubMed Central

Gu, Yunfu; D. Van Nostrand, Joy; Wu, Liyou; He, Zhili; Qin, Yujia; Zhao, Fang-Jie; Zhou, Jizhong

2017-01-01

To understand how soil microbial communities and arsenic (As) functional genes respond to soil arsenic (As) contamination, five soils contaminated with As at different levels were collected from diverse geographic locations, incubated for 54 days under flooded conditions, and examined by both MiSeq sequencing of 16S rRNA gene amplicons and functional gene microarray (GeoChip 4.0). The results showed that both bacterial community structure and As functional gene structure differed among geographical locations. The diversity of As functional genes correlated positively with the diversity of 16S rRNA genes (P< 0.05). Higher diversities of As functional genes and 16S rRNA genes were observed in the soils with higher available As. Soil pH, phosphate-extractable As, and amorphous Fe content were the most important factors in shaping the bacterial community structure and As transformation functional genes. Geographic location was also important in controlling both the bacterial community and As transformation functional potential. These findings provide insights into the variation of As transformation functional genes in soils contaminated with different levels of As at different geographic locations, and the impact of environmental As contamination on the soil bacterial community. PMID:28475654

An exceptional horizontal gene transfer in plastids: gene replacement by a distant bacterial paralog and evidence that haptophyte and cryptophyte plastids are sisters

PubMed Central

Rice, Danny W; Palmer, Jeffrey D

2006-01-01

Background Horizontal gene transfer (HGT) to the plant mitochondrial genome has recently been shown to occur at a surprisingly high rate; however, little evidence has been found for HGT to the plastid genome, despite extensive sequencing. In this study, we analyzed all genes from sequenced plastid genomes to unearth any neglected cases of HGT and to obtain a measure of the overall extent of HGT to the plastid. Results Although several genes gave strongly supported conflicting trees under certain conditions, we are confident of HGT in only a single case beyond the rubisco HGT already reported. Most of the conflicts involved near neighbors connected by long branches (e.g. red algae and their secondary hosts), where phylogenetic methods are prone to mislead. However, three genes – clpP, ycf2, and rpl36 – provided strong support for taxa moving far from their organismal position. Further taxon sampling of clpP and ycf2 resulted in rejection of HGT due to long-branch attraction and a serious error in the published plastid genome sequence of Oenothera elata, respectively. A single new case, a bacterial rpl36 gene transferred into the ancestor of the cryptophyte and haptophyte plastids, appears to be a true HGT event. Interestingly, this rpl36 gene is a distantly related paralog of the rpl36 type found in other plastids and most eubacteria. Moreover, the transferred gene has physically replaced the native rpl36 gene, yet flanking genes and intergenic regions show no sign of HGT. This suggests that gene replacement somehow occurred by recombination at the very ends of rpl36, without the level and length of similarity normally expected to support recombination. Conclusion The rpl36 HGT discovered in this study is of considerable interest in terms of both molecular mechanism and phylogeny. The plastid acquisition of a bacterial rpl36 gene via HGT provides the first strong evidence for a sister-group relationship between haptophyte and cryptophyte plastids to the

Ingestion of bacterially expressed double-stranded RNA inhibits gene expression in planarians.

PubMed

Newmark, Phillip A; Reddien, Peter W; Cebrià, Francesc; Sánchez Alvarado, Alejandro

2003-09-30

Freshwater planarian flatworms are capable of regenerating complete organisms from tiny fragments of their bodies; the basis for this regenerative prowess is an experimentally accessible stem cell population that is present in the adult planarian. The study of these organisms, classic experimental models for investigating metazoan regeneration, has been revitalized by the application of modern molecular biological approaches. The identification of thousands of unique planarian ESTs, coupled with large-scale whole-mount in situ hybridization screens, and the ability to inhibit planarian gene expression through double-stranded RNA-mediated genetic interference, provide a wealth of tools for studying the molecular mechanisms that regulate tissue regeneration and stem cell biology in these organisms. Here we show that, as in Caenorhabditis elegans, ingestion of bacterially expressed double-stranded RNA can inhibit gene expression in planarians. This inhibition persists throughout the process of regeneration, allowing phenotypes with disrupted regenerative patterning to be identified. These results pave the way for large-scale screens for genes involved in regenerative processes.

Encyclopedia of bacterial gene circuits whose presence or absence correlate with pathogenicity--a large-scale system analysis of decoded bacterial genomes.

PubMed

Shestov, Maksim; Ontañón, Santiago; Tozeren, Aydin

2015-10-13

Bacterial infections comprise a global health challenge as the incidences of antibiotic resistance increase. Pathogenic potential of bacteria has been shown to be context dependent, varying in response to environment and even within the strains of the same genus. We used the KEGG repository and extensive literature searches to identify among the 2527 bacterial genomes in the literature those implicated as pathogenic to the host, including those which show pathogenicity in a context dependent manner. Using data on the gene contents of these genomes, we identified sets of genes highly abundant in pathogenic but relatively absent in commensal strains and vice versa. In addition, we carried out genome comparison within a genus for the seventeen largest genera in our genome collection. We projected the resultant lists of ortholog genes onto KEGG bacterial pathways to identify clusters and circuits, which can be linked to either pathogenicity or synergy. Gene circuits relatively abundant in nonpathogenic bacteria often mediated biosynthesis of antibiotics. Other synergy-linked circuits reduced drug-induced toxicity. Pathogen-abundant gene circuits included modules in one-carbon folate, two-component system, type-3 secretion system, and peptidoglycan biosynthesis. Antibiotics-resistant bacterial strains possessed genes modulating phagocytosis, vesicle trafficking, cytoskeletal reorganization, and regulation of the inflammatory response. Our study also identified bacterial genera containing a circuit, elements of which were previously linked to Alzheimer's disease. Present study produces for the first time, a signature, in the form of a robust list of gene circuitry whose presence or absence could potentially define the pathogenicity of a microbiome. Extensive literature search substantiated a bulk majority of the commensal and pathogenic circuitry in our predicted list. Scanning microbiome libraries for these circuitry motifs will provide further insights into the complex

Dynamics of Immune System Gene Expression upon Bacterial Challenge and Wounding in a Social Insect (Bombus terrestris)

PubMed Central

Erler, Silvio; Popp, Mario; Lattorff, H. Michael G.

2011-01-01

The innate immune system which helps individuals to combat pathogens comprises a set of genes representing four immune system pathways (Toll, Imd, JNK and JAK/STAT). There is a lack of immune genes in social insects (e.g. honeybees) when compared to Diptera. Potentially, this might be compensated by an advanced system of social immunity (synergistic action of several individuals). The bumble bee, Bombus terrestris, is a primitively eusocial species with an annual life cycle and colonies headed by a single queen. We used this key pollinator to study the temporal dynamics of immune system gene expression in response to wounding and bacterial challenge. Antimicrobial peptides (AMP) (abaecin, defensin 1, hymenoptaecin) were strongly up-regulated by wounding and bacterial challenge, the latter showing a higher impact on the gene expression level. Sterile wounding down-regulated TEP A, an effector gene of the JAK/STAT pathway, and bacterial infection influenced genes of the Imd (relish) and JNK pathway (basket). Relish was up-regulated within the first hour after bacterial challenge, but decreased strongly afterwards. AMP expression following wounding and bacterial challenge correlates with the expression pattern of relish whereas correlated expression with dorsal was absent. Although expression of AMPs was high, continuous bacterial growth was observed throughout the experiment. Here we demonstrate for the first time the temporal dynamics of immune system gene expression in a social insect. Wounding and bacterial challenge affected the innate immune system significantly. Induction of AMP expression due to wounding might comprise a pre-adaptation to accompanying bacterial infections. Compared with solitary species this social insect exhibits reduced immune system efficiency, as bacterial growth could not be inhibited. A negative feedback loop regulating the Imd-pathway is suggested. AMPs, the end product of the Imd-pathway, inhibited the up-regulation of the

Gene expression in gut symbiotic organ of stinkbug affected by extracellular bacterial symbiont.

PubMed

Futahashi, Ryo; Tanaka, Kohjiro; Tanahashi, Masahiko; Nikoh, Naruo; Kikuchi, Yoshitomo; Lee, Bok Luel; Fukatsu, Takema

2013-01-01

The bean bug Riptortus pedestris possesses a specialized symbiotic organ in a posterior region of the midgut, where numerous crypts harbor extracellular betaproteobacterial symbionts of the genus Burkholderia. Second instar nymphs orally acquire the symbiont from the environment, and the symbiont infection benefits the host by facilitating growth and by occasionally conferring insecticide resistance. Here we performed comparative transcriptomic analyses of insect genes expressed in symbiotic and non-symbiotic regions of the midgut dissected from Burkholderia-infected and uninfected R. pedestris. Expression sequence tag analysis of cDNA libraries and quantitative reverse transcription PCR identified a number of insect genes expressed in symbiosis- or aposymbiosis-associated patterns. For example, genes up-regulated in symbiotic relative to aposymbiotic individuals, including many cysteine-rich secreted protein genes and many cathepsin protease genes, are likely to play a role in regulating the symbiosis. Conversely, genes up-regulated in aposymbiotic relative to symbiotic individuals, including a chicken-type lysozyme gene and a defensin-like protein gene, are possibly involved in regulation of non-symbiotic bacterial infections. Our study presents the first transcriptomic data on gut symbiotic organ of a stinkbug, which provides initial clues to understanding of molecular mechanisms underlying the insect-bacterium gut symbiosis and sheds light on several intriguing commonalities between endocellular and extracellular symbiotic associations.

Multiple conversion between the genes encoding bacterial class-I release factors

PubMed Central

Ishikawa, Sohta A.; Kamikawa, Ryoma; Inagaki, Yuji

2015-01-01

Bacteria require two class-I release factors, RF1 and RF2, that recognize stop codons and promote peptide release from the ribosome. RF1 and RF2 were most likely established through gene duplication followed by altering their stop codon specificities in the common ancestor of extant bacteria. This scenario expects that the two RF gene families have taken independent evolutionary trajectories after the ancestral gene duplication event. However, we here report two independent cases of conversion between RF1 and RF2 genes (RF1-RF2 gene conversion), which were severely examined by procedures incorporating the maximum-likelihood phylogenetic method. In both cases, RF1-RF2 gene conversion was predicted to occur in the region encoding nearly entire domain 3, of which functions are common between RF paralogues. Nevertheless, the ‘direction’ of gene conversion appeared to be opposite from one another—from RF2 gene to RF1 gene in one case, while from RF1 gene to RF2 gene in the other. The two cases of RF1-RF2 gene conversion prompt us to propose two novel aspects in the evolution of bacterial class-I release factors: (i) domain 3 is interchangeable between RF paralogues, and (ii) RF1-RF2 gene conversion have occurred frequently in bacterial genome evolution. PMID:26257102

The Composition and Spatial Patterns of Bacterial Virulence Factors and Antibiotic Resistance Genes in 19 Wastewater Treatment Plants

PubMed Central

Zhang, Bing; Xia, Yu; Wen, Xianghua; Wang, Xiaohui; Yang, Yunfeng; Zhou, Jizhong; Zhang, Yu

2016-01-01

Bacterial pathogenicity and antibiotic resistance are of concern for environmental safety and public health. Accumulating evidence suggests that wastewater treatment plants (WWTPs) are as an important sink and source of pathogens and antibiotic resistance genes (ARGs). Virulence genes (encoding virulence factors) are good indicators for bacterial pathogenic potentials. To achieve a comprehensive understanding of bacterial pathogenic potentials and antibiotic resistance in WWTPs, bacterial virulence genes and ARGs in 19 WWTPs covering a majority of latitudinal zones of China were surveyed by using GeoChip 4.2. A total of 1610 genes covering 13 virulence factors and 1903 genes belonging to 11 ARG families were detected respectively. The bacterial virulence genes exhibited significant spatial distribution patterns of a latitudinal biodiversity gradient and a distance-decay relationship across China. Moreover, virulence genes tended to coexist with ARGs as shown by their strongly positive associations. In addition, key environmental factors shaping the overall virulence gene structure were identified. This study profiles the occurrence, composition and distribution of virulence genes and ARGs in current WWTPs in China, and uncovers spatial patterns and important environmental variables shaping their structure, which may provide the basis for further studies of bacterial virulence factors and antibiotic resistance in WWTPs. PMID:27907117

Expression of the Bs2 pepper gene confers resistance to bacterial spot disease in tomato

PubMed Central

Tai, Thomas H.; Dahlbeck, Douglas; Clark, Eszter T.; Gajiwala, Paresh; Pasion, Romela; Whalen, Maureen C.; Stall, Robert E.; Staskawicz, Brian J.

1999-01-01

The Bs2 resistance gene of pepper specifically recognizes and confers resistance to strains of Xanthomonas campestris pv. vesicatoria that contain the corresponding bacterial avirulence gene, avrBs2. The involvement of avrBs2 in pathogen fitness and its prevalence in many X. campestris pathovars suggests that the Bs2 gene may be durable in the field and provide resistance when introduced into other plant species. Employing a positional cloning strategy, the Bs2 locus was isolated and the gene was identified by coexpression with avrBs2 in an Agrobacterium-mediated transient assay. A single candidate gene, predicted to encode motifs characteristic of the nucleotide binding site–leucine-rich repeat class of resistance genes, was identified. This gene specifically controlled the hypersensitive response when transiently expressed in susceptible pepper and tomato lines and in a nonhost species, Nicotiana benthamiana, and was designated as Bs2. Functional expression of Bs2 in stable transgenic tomatoes supports its use as a source of resistance in other Solanaceous plant species. PMID:10570214

Expression of the Bs2 pepper gene confers resistance to bacterial spot disease in tomato.

PubMed

Tai, T H; Dahlbeck, D; Clark, E T; Gajiwala, P; Pasion, R; Whalen, M C; Stall, R E; Staskawicz, B J

1999-11-23

The Bs2 resistance gene of pepper specifically recognizes and confers resistance to strains of Xanthomonas campestris pv. vesicatoria that contain the corresponding bacterial avirulence gene, avrBs2. The involvement of avrBs2 in pathogen fitness and its prevalence in many X. campestris pathovars suggests that the Bs2 gene may be durable in the field and provide resistance when introduced into other plant species. Employing a positional cloning strategy, the Bs2 locus was isolated and the gene was identified by coexpression with avrBs2 in an Agrobacterium-mediated transient assay. A single candidate gene, predicted to encode motifs characteristic of the nucleotide binding site-leucine-rich repeat class of resistance genes, was identified. This gene specifically controlled the hypersensitive response when transiently expressed in susceptible pepper and tomato lines and in a nonhost species, Nicotiana benthamiana, and was designated as Bs2. Functional expression of Bs2 in stable transgenic tomatoes supports its use as a source of resistance in other Solanaceous plant species.

The plant pathogenic fungus Gaeumannomyces graminis var. tritici improves bacterial growth and triggers early gene regulations in the biocontrol strain Pseudomonas fluorescens Pf29Arp.

PubMed

Barret, M; Frey-Klett, P; Boutin, M; Guillerm-Erckelboudt, A-Y; Martin, F; Guillot, L; Sarniguet, A

2009-01-01

In soil, some antagonistic rhizobacteria contribute to reduce root diseases caused by phytopathogenic fungi. Direct modes of action of these bacteria have been largely explored; however, commensal interaction also takes place between these microorganisms and little is known about the influence of filamentous fungi on bacteria. An in vitro confrontation bioassay between the pathogenic fungus Gaeumannomyces graminis var. tritici (Ggt) and the biocontrol bacterial strain Pseudomonas fluorescens Pf29Arp was set up to analyse bacterial transcriptional changes induced by the fungal mycelium at three time-points of the interaction before cell contact and up until contact. For this, a Pf29Arp shotgun DNA microarray was constructed. Specifity of Ggt effect was assessed in comparison with one of two other filamentous fungi, Laccaria bicolor and Magnaporthe grisea. During a commensal interaction, Ggt increased the growth rate of Pf29Arp. Before contact, Ggt induced bacterial genes involved in mycelium colonization. At contact, genes encoding protein of stress response and a patatin-like protein were up-regulated. Among all the bacterial genes identified, xseB was specifically up-regulated at contact by Ggt but down-regulated by the other fungi. Data showed that the bacterium sensed the presence of the fungus early, but the main gene alteration occurred during bacterial-fungal cell contact.

Messing with Bacterial Quorum Sensing

PubMed Central

González, Juan E.; Keshavan, Neela D.

2006-01-01

Quorum sensing is widely recognized as an efficient mechanism to regulate expression of specific genes responsible for communal behavior in bacteria. Several bacterial phenotypes essential for the successful establishment of symbiotic, pathogenic, or commensal relationships with eukaryotic hosts, including motility, exopolysaccharide production, biofilm formation, and toxin production, are often regulated by quorum sensing. Interestingly, eukaryotes produce quorum-sensing-interfering (QSI) compounds that have a positive or negative influence on the bacterial signaling network. This eukaryotic interference could result in further fine-tuning of bacterial quorum sensing. Furthermore, recent work involving the synthesis of structural homologs to the various quorum-sensing signal molecules has resulted in the development of additional QSI compounds that could be used to control pathogenic bacteria. The creation of transgenic plants that express bacterial quorum-sensing genes is yet another strategy to interfere with bacterial behavior. Further investigation on the manipulation of quorum-sensing systems could provide us with powerful tools against harmful bacteria. PMID:17158701

Plagiarized bacterial genes in the human book of life.

PubMed

Ponting, C P

2001-05-01

The initial analysis of the human genome draft sequence reveals that our 'book of life' is multi-authored. A small but significant proportion of our genes owes their heritage not to antecedent eukaryotes but instead to bacteria. The publicly funded Human Genome Project study indicates that about 0.5% of all human genes were copied into the genome from bacterial sources. Detailed sequence analyses point to these 'horizontal gene transfer' events having occurred relatively recently. So how did the human 'book of life' evolve to be a chimaera, part animal and part bacterium? And what was the probable evolutionary impact of such gene plagiarism?

Linearmycins Activate a Two-Component Signaling System Involved in Bacterial Competition and Biofilm Morphology

PubMed Central

2017-01-01

includes the gastrointestinal tract of animals and the rhizosphere of plants. Interactions between different species in bacterial communities have impacts on our health and industry. However, many approaches currently used to study whole bacterial communities do not resolve mechanistic details of interspecies interactions, including how bacteria sense and respond to their competitors. Using a competition model, we have uncovered dual functions for a previously uncharacterized two-component signaling system involved in specific antibiotic resistance and biofilm morphology. Insights gleaned from signaling within interspecies interaction models build a more complete understanding of gene functions important for bacterial communities and will enhance community-level analytical approaches. PMID:28461449

Functional and Evolutionary Characterization of a UDP-Xylose Synthase Gene from the Plant Pathogen Xylella fastidiosa, Involved in the Synthesis of Bacterial Lipopolysaccharide.

PubMed

Alencar, Valquíria Campos; Jabes, Daniela Leite; Menegidio, Fabiano Bezerra; Sassaki, Guilherme Lanzi; de Souza, Lucas Rodrigo; Puzer, Luciano; Meneghetti, Maria Cecília Zorél; Lima, Marcelo Andrade; Tersariol, Ivarne Luis Dos Santos; de Oliveira, Regina Costa; Nunes, Luiz R

2017-02-07

Xylella fastidiosa is a plant-infecting bacillus, responsible for many important crop diseases, such as Pierce's disease of vineyards, citrus variegated chlorosis, and coffee leaf scorch (CLS), among others. Recent genomic comparisons involving two CLS-related strains, belonging to X. fastidiosa subsp. pauca, revealed that one of them carries a frameshift mutation that inactivates a gene encoding an oxidoreductase of the short-chain dehydrogenase/reductase (SDR) superfamily, which may play important roles in determining structural variations in bacterial glycans and glycoconjugates. However, the exact nature of this SDR has been a matter of controversy, as different annotations of X. fastidiosa genomes have implicated it in distinct reactions. To confirm the nature of this mutated SDR, a comparative analysis was initially performed, suggesting that it belongs to a subgroup of SDR decarboxylases, representing a UDP-xylose synthase (Uxs). Functional assays, using a recombinant derivative of this enzyme, confirmed its nature as XfUxs, and carbohydrate composition analyses, performed with lipopolysaccharide (LPS) molecules obtained from different strains, indicate that inactivation of the X. fastidiosa uxs gene affects the LPS structure among CLS-related X. fastidiosa strains. Finally, a comparative sequence analysis suggests that this mutation is likely to result in a morphological and evolutionary hallmark that differentiates two subgroups of CLS-related strains, which may influence interactions between these bacteria and their plant and/or insect hosts.

Systematic bacterialization of yeast genes identifies a near-universally swappable pathway

PubMed Central

Kachroo, Aashiq H; Laurent, Jon M; Akhmetov, Azat; Szilagyi-Jones, Madelyn; McWhite, Claire D; Zhao, Alice; Marcotte, Edward M

2017-01-01

Eukaryotes and prokaryotes last shared a common ancestor ~2 billion years ago, and while many present-day genes in these lineages predate this divergence, the extent to which these genes still perform their ancestral functions is largely unknown. To test principles governing retention of ancient function, we asked if prokaryotic genes could replace their essential eukaryotic orthologs. We systematically replaced essential genes in yeast by their 1:1 orthologs from Escherichia coli. After accounting for mitochondrial localization and alternative start codons, 31 out of 51 bacterial genes tested (61%) could complement a lethal growth defect and replace their yeast orthologs with minimal effects on growth rate. Replaceability was determined on a pathway-by-pathway basis; codon usage, abundance, and sequence similarity contributed predictive power. The heme biosynthesis pathway was particularly amenable to inter-kingdom exchange, with each yeast enzyme replaceable by its bacterial, human, or plant ortholog, suggesting it as a near-universally swappable pathway. DOI: http://dx.doi.org/10.7554/eLife.25093.001 PMID:28661399

Gene Expression in Gut Symbiotic Organ of Stinkbug Affected by Extracellular Bacterial Symbiont

PubMed Central

Futahashi, Ryo; Tanaka, Kohjiro; Tanahashi, Masahiko; Nikoh, Naruo; Kikuchi, Yoshitomo; Lee, Bok Luel; Fukatsu, Takema

2013-01-01

The bean bug Riptortus pedestris possesses a specialized symbiotic organ in a posterior region of the midgut, where numerous crypts harbor extracellular betaproteobacterial symbionts of the genus Burkholderia. Second instar nymphs orally acquire the symbiont from the environment, and the symbiont infection benefits the host by facilitating growth and by occasionally conferring insecticide resistance. Here we performed comparative transcriptomic analyses of insect genes expressed in symbiotic and non-symbiotic regions of the midgut dissected from Burkholderia-infected and uninfected R. pedestris. Expression sequence tag analysis of cDNA libraries and quantitative reverse transcription PCR identified a number of insect genes expressed in symbiosis- or aposymbiosis-associated patterns. For example, genes up-regulated in symbiotic relative to aposymbiotic individuals, including many cysteine-rich secreted protein genes and many cathepsin protease genes, are likely to play a role in regulating the symbiosis. Conversely, genes up-regulated in aposymbiotic relative to symbiotic individuals, including a chicken-type lysozyme gene and a defensin-like protein gene, are possibly involved in regulation of non-symbiotic bacterial infections. Our study presents the first transcriptomic data on gut symbiotic organ of a stinkbug, which provides initial clues to understanding of molecular mechanisms underlying the insect-bacterium gut symbiosis and sheds light on several intriguing commonalities between endocellular and extracellular symbiotic associations. PMID:23691247

Interplay of Noisy Gene Expression and Dynamics Explains Patterns of Bacterial Operon Organization

NASA Astrophysics Data System (ADS)

Igoshin, Oleg

2011-03-01

Bacterial chromosomes are organized into operons -- sets of genes co-transcribed into polycistronic messenger RNA. Hypotheses explaining the emergence and maintenance of operons include proportional co-regulation, horizontal transfer of intact ``selfish'' operons, emergence via gene duplication, and co-production of physically interacting proteins to speed their association. We hypothesized an alternative: operons can reduce or increase intrinsic gene expression noise in a manner dependent on the post-translational interactions, thereby resulting in selection for or against operons in depending on the network architecture. We devised five classes of two-gene network modules and show that the effects of operons on intrinsic noise depend on class membership. Two classes exhibit decreased noise with co-transcription, two others reveal increased noise, and the remaining one does not show a significant difference. To test our modeling predictions we employed bioinformatic analysis to determine the relationship gene expression noise and operon organization. The results confirm the overrepresentation of noise-minimizing operon architectures and provide evidence against other hypotheses. Our results thereby suggest a central role for gene expression noise in selecting for or maintaining operons in bacterial chromosomes. This demonstrates how post-translational network dynamics may provide selective pressure for organizing bacterial chromosomes, and has practical consequences for designing synthetic gene networks. This work is supported by National Institutes of Health grant 1R01GM096189-01.

Gene calling and bacterial genome annotation with BG7.

PubMed

Tobes, Raquel; Pareja-Tobes, Pablo; Manrique, Marina; Pareja-Tobes, Eduardo; Kovach, Evdokim; Alekhin, Alexey; Pareja, Eduardo

2015-01-01

New massive sequencing technologies are providing many bacterial genome sequences from diverse taxa but a refined annotation of these genomes is crucial for obtaining scientific findings and new knowledge. Thus, bacterial genome annotation has emerged as a key point to investigate in bacteria. Any efficient tool designed specifically to annotate bacterial genomes sequenced with massively parallel technologies has to consider the specific features of bacterial genomes (absence of introns and scarcity of nonprotein-coding sequence) and of next-generation sequencing (NGS) technologies (presence of errors and not perfectly assembled genomes). These features make it convenient to focus on coding regions and, hence, on protein sequences that are the elements directly related with biological functions. In this chapter we describe how to annotate bacterial genomes with BG7, an open-source tool based on a protein-centered gene calling/annotation paradigm. BG7 is specifically designed for the annotation of bacterial genomes sequenced with NGS. This tool is sequence error tolerant maintaining their capabilities for the annotation of highly fragmented genomes or for annotating mixed sequences coming from several genomes (as those obtained through metagenomics samples). BG7 has been designed with scalability as a requirement, with a computing infrastructure completely based on cloud computing (Amazon Web Services).

Characterization of a bacterial tyrosine kinase in Porphyromonas gingivalis involved in polymicrobial synergy.

PubMed

Wright, Christopher J; Xue, Peng; Hirano, Takanori; Liu, Chengcheng; Whitmore, Sarah E; Hackett, Murray; Lamont, Richard J

2014-06-01

Interspecies communication between Porphyromonas gingivalis and Streptococcus gordonii underlies the development of synergistic dual species communities. Contact with S. gordonii initiates signal transduction within P. gingivalis that is based on protein tyrosine (de)phosphorylation. In this study, we characterize a bacterial tyrosine (BY) kinase (designated Ptk1) of P. gingivalis and demonstrate its involvement in interspecies signaling. Ptk1 can utilize ATP for autophosphorylation and is dephosphorylated by the P. gingivalis tyrosine phosphatase, Ltp1. Community development with S. gordonii is severely abrogated in a ptk1 mutant of P. gingivalis, indicating that tyrosine kinase activity is required for maximal polymicrobial synergy. Ptk1 controls the levels of the transcriptional regulator CdhR and the fimbrial adhesin Mfa1 which mediates binding to S. gordonii. The ptk1 gene is in an operon with two genes involved in exopolysaccharide synthesis, and similar to other BY kinases, Ptk1 is necessary for exopolysaccharide production in P. gingivalis. Ptk1 can phosphorylate the capsule related proteins PGN_0224, a UDP-acetyl-mannosamine dehydrogenase, and PGN_0613, a UDP-glucose dehydrogenase, in P. gingivalis. Knockout of ptk1 in an encapsulated strain of P. gingivalis resulted in loss of capsule production. Collectively these results demonstrate that the P. gingivalis Ptk1 BY kinase regulates interspecies communication and controls heterotypic community development with S. gordonii through adjusting the levels of the Mfa1 adhesin and exopolysaccharide. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

A BAC-bacterial recombination method to generate physically linked multiple gene reporter DNA constructs.

PubMed

Maye, Peter; Stover, Mary Louise; Liu, Yaling; Rowe, David W; Gong, Shiaochin; Lichtler, Alexander C

2009-03-13

Reporter gene mice are valuable animal models for biological research providing a gene expression readout that can contribute to cellular characterization within the context of a developmental process. With the advancement of bacterial recombination techniques to engineer reporter gene constructs from BAC genomic clones and the generation of optically distinguishable fluorescent protein reporter genes, there is an unprecedented capability to engineer more informative transgenic reporter mouse models relative to what has been traditionally available. We demonstrate here our first effort on the development of a three stage bacterial recombination strategy to physically link multiple genes together with their respective fluorescent protein (FP) reporters in one DNA fragment. This strategy uses bacterial recombination techniques to: (1) subclone genes of interest into BAC linking vectors, (2) insert desired reporter genes into respective genes and (3) link different gene-reporters together. As proof of concept, we have generated a single DNA fragment containing the genes Trap, Dmp1, and Ibsp driving the expression of ECFP, mCherry, and Topaz FP reporter genes, respectively. Using this DNA construct, we have successfully generated transgenic reporter mice that retain two to three gene readouts. The three stage methodology to link multiple genes with their respective fluorescent protein reporter works with reasonable efficiency. Moreover, gene linkage allows for their common chromosomal integration into a single locus. However, the testing of this multi-reporter DNA construct by transgenesis does suggest that the linkage of two different genes together, despite their large size, can still create a positional effect. We believe that gene choice, genomic DNA fragment size and the presence of endogenous insulator elements are critical variables.

Statistical Analysis of Hurst Exponents of Essential/Nonessential Genes in 33 Bacterial Genomes

PubMed Central

Liu, Xiao; Wang, Baojin; Xu, Luo

2015-01-01

Methods for identifying essential genes currently depend predominantly on biochemical experiments. However, there is demand for improved computational methods for determining gene essentiality. In this study, we used the Hurst exponent, a characteristic parameter to describe long-range correlation in DNA, and analyzed its distribution in 33 bacterial genomes. In most genomes (31 out of 33) the significance levels of the Hurst exponents of the essential genes were significantly higher than for the corresponding full-gene-set, whereas the significance levels of the Hurst exponents of the nonessential genes remained unchanged or increased only slightly. All of the Hurst exponents of essential genes followed a normal distribution, with one exception. We therefore propose that the distribution feature of Hurst exponents of essential genes can be used as a classification index for essential gene prediction in bacteria. For computer-aided design in the field of synthetic biology, this feature can build a restraint for pre- or post-design checking of bacterial essential genes. Moreover, considering the relationship between gene essentiality and evolution, the Hurst exponents could be used as a descriptive parameter related to evolutionary level, or be added to the annotation of each gene. PMID:26067107

Bacteria and Genes Involved in Arsenic Speciation in Sediment Impacted by Long-Term Gold Mining

PubMed Central

Costa, Patrícia S.; Scholte, Larissa L. S.; Reis, Mariana P.; Chaves, Anderson V.; Oliveira, Pollyanna L.; Itabayana, Luiza B.; Suhadolnik, Maria Luiza S.; Barbosa, Francisco A. R.; Chartone-Souza, Edmar; Nascimento, Andréa M. A.

2014-01-01

The bacterial community and genes involved in geobiocycling of arsenic (As) from sediment impacted by long-term gold mining were characterized through culture-based analysis of As-transforming bacteria and metagenomic studies of the arsC, arrA, and aioA genes. Sediment was collected from the historically gold mining impacted Mina stream, located in one of the world’s largest mining regions known as the “Iron Quadrangle”. A total of 123 As-resistant bacteria were recovered from the enrichment cultures, which were phenotypically and genotypically characterized for As-transformation. A diverse As-resistant bacteria community was found through phylogenetic analyses of the 16S rRNA gene. Bacterial isolates were affiliated with Proteobacteria, Firmicutes, and Actinobacteria and were represented by 20 genera. Most were AsV-reducing (72%), whereas AsIII-oxidizing accounted for 20%. Bacteria harboring the arsC gene predominated (85%), followed by aioA (20%) and arrA (7%). Additionally, we identified two novel As-transforming genera, Thermomonas and Pannonibacter. Metagenomic analysis of arsC, aioA, and arrA sequences confirmed the presence of these genes, with arrA sequences being more closely related to uncultured organisms. Evolutionary analyses revealed high genetic similarity between some arsC and aioA sequences obtained from isolates and clone libraries, suggesting that those isolates may represent environmentally important bacteria acting in As speciation. In addition, our findings show that the diversity of arrA genes is wider than earlier described, once none arrA-OTUs were affiliated with known reference strains. Therefore, the molecular diversity of arrA genes is far from being fully explored deserving further attention. PMID:24755825

Alignment-free detection of horizontal gene transfer between closely related bacterial genomes.

PubMed

Domazet-Lošo, Mirjana; Haubold, Bernhard

2011-09-01

Bacterial epidemics are often caused by strains that have acquired their increased virulence through horizontal gene transfer. Due to this association with disease, the detection of horizontal gene transfer continues to receive attention from microbiologists and bioinformaticians alike. Most software for detecting transfer events is based on alignments of sets of genes or of entire genomes. But despite great advances in the design of algorithms and computer programs, genome alignment remains computationally challenging. We have therefore developed an alignment-free algorithm for rapidly detecting horizontal gene transfer between closely related bacterial genomes. Our implementation of this algorithm is called alfy for "ALignment Free local homologY" and is freely available from http://guanine.evolbio.mpg.de/alfy/. In this comment we demonstrate the application of alfy to the genomes of Staphylococcus aureus. We also argue that-contrary to popular belief and in spite of increasing computer speed-algorithmic optimization is becoming more, not less, important if genome data continues to accumulate at the present rate.

Global analysis of gene expression reveals mRNA superinduction is required for the inducible immune response to a bacterial pathogen

PubMed Central

Barry, Kevin C; Ingolia, Nicholas T; Vance, Russell E

2017-01-01

The inducible innate immune response to infection requires a concerted process of gene expression that is regulated at multiple levels. Most global analyses of the innate immune response have focused on transcription induced by defined immunostimulatory ligands, such as lipopolysaccharide. However, the response to pathogens involves additional complexity, as pathogens interfere with virtually every step of gene expression. How cells respond to pathogen-mediated disruption of gene expression to nevertheless initiate protective responses remains unclear. We previously discovered that a pathogen-mediated blockade of host protein synthesis provokes the production of specific pro-inflammatory cytokines. It remains unclear how these cytokines are produced despite the global pathogen-induced block of translation. We addressed this question by using parallel RNAseq and ribosome profiling to characterize the response of macrophages to infection with the intracellular bacterial pathogen Legionella pneumophila. Our results reveal that mRNA superinduction is required for the inducible immune response to a bacterial pathogen. DOI: http://dx.doi.org/10.7554/eLife.22707.001 PMID:28383283

Genetic Diversity of Bacterial Communities and Gene Transfer Agents in Northern South China Sea

PubMed Central

Sun, Fu-Lin; Wang, You-Shao; Wu, Mei-Lin; Jiang, Zhao-Yu; Sun, Cui-Ci; Cheng, Hao

2014-01-01

Pyrosequencing of the 16S ribosomal RNA gene (rDNA) amplicons was performed to investigate the unique distribution of bacterial communities in northern South China Sea (nSCS) and evaluate community structure and spatial differences of bacterial diversity. Cyanobacteria, Proteobacteria, Actinobacteria, and Bacteroidetes constitute the majority of bacteria. The taxonomic description of bacterial communities revealed that more Chroococcales, SAR11 clade, Acidimicrobiales, Rhodobacterales, and Flavobacteriales are present in the nSCS waters than other bacterial groups. Rhodobacterales were less abundant in tropical water (nSCS) than in temperate and cold waters. Furthermore, the diversity of Rhodobacterales based on the gene transfer agent (GTA) major capsid gene (g5) was investigated. Four g5 gene clone libraries were constructed from samples representing different regions and yielded diverse sequences. Fourteen g5 clusters could be identified among 197 nSCS clones. These clusters were also related to known g5 sequences derived from genome-sequenced Rhodobacterales. The composition of g5 sequences in surface water varied with the g5 sequences in the sampling sites; this result indicated that the Rhodobacterales population could be highly diverse in nSCS. Phylogenetic tree analysis result indicated distinguishable diversity patterns among tropical (nSCS), temperate, and cold waters, thereby supporting the niche adaptation of specific Rhodobacterales members in unique environments. PMID:25364820

Reduced Set of Virulence Genes Allows High Accuracy Prediction of Bacterial Pathogenicity in Humans

PubMed Central

Iraola, Gregorio; Vazquez, Gustavo; Spangenberg, Lucía; Naya, Hugo

2012-01-01

Although there have been great advances in understanding bacterial pathogenesis, there is still a lack of integrative information about what makes a bacterium a human pathogen. The advent of high-throughput sequencing technologies has dramatically increased the amount of completed bacterial genomes, for both known human pathogenic and non-pathogenic strains; this information is now available to investigate genetic features that determine pathogenic phenotypes in bacteria. In this work we determined presence/absence patterns of different virulence-related genes among more than finished bacterial genomes from both human pathogenic and non-pathogenic strains, belonging to different taxonomic groups (i.e: Actinobacteria, Gammaproteobacteria, Firmicutes, etc.). An accuracy of 95% using a cross-fold validation scheme with in-fold feature selection is obtained when classifying human pathogens and non-pathogens. A reduced subset of highly informative genes () is presented and applied to an external validation set. The statistical model was implemented in the BacFier v1.0 software (freely available at ), that displays not only the prediction (pathogen/non-pathogen) and an associated probability for pathogenicity, but also the presence/absence vector for the analyzed genes, so it is possible to decipher the subset of virulence genes responsible for the classification on the analyzed genome. Furthermore, we discuss the biological relevance for bacterial pathogenesis of the core set of genes, corresponding to eight functional categories, all with evident and documented association with the phenotypes of interest. Also, we analyze which functional categories of virulence genes were more distinctive for pathogenicity in each taxonomic group, which seems to be a completely new kind of information and could lead to important evolutionary conclusions. PMID:22916122

Structure and variation of three canine genes involved in serotonin binding and transport: the serotonin receptor 1A gene (htr1A), serotonin receptor 2A gene (htr2A), and serotonin transporter gene (slc6A4).

PubMed

van den Berg, L; Kwant, L; Hestand, M S; van Oost, B A; Leegwater, P A J

2005-01-01

Aggressive behavior is the most frequently encountered behavioral problem in dogs. Abnormalities in brain serotonin metabolism have been described in aggressive dogs. We studied canine serotonergic genes to investigate genetic factors underlying canine aggression. Here, we describe the characterization of three genes of the canine serotonergic system: the serotonin receptor 1A and 2A gene (htr1A and htr2A) and the serotonin transporter gene (slc6A4). We isolated canine bacterial artificial chromosome clones containing these genes and designed oligonucleotides for genomic sequencing of coding regions and intron-exon boundaries. Golden retrievers were analyzed for DNA sequence variations. We found two nonsynonymous single nucleotide polymorphisms (SNPs) in the coding sequence of htr1A; one SNP close to a splice site in htr2A; and two SNPs in slc6A4, one in the coding sequence and one close to a splice site. In addition, we identified a polymorphic microsatellite marker for each gene. Htr1A is a strong candidate for involvement in the domestication of the dog. We genotyped the htr1A SNPs in 41 dogs of seven breeds with diverse behavioral characteristics. At least three SNP haplotypes were found. Our results do not support involvement of the gene in domestication.

Application of Chemical Genomics to Plant-Bacteria Communication: A High-Throughput System to Identify Novel Molecules Modulating the Induction of Bacterial Virulence Genes by Plant Signals.

PubMed

Vandelle, Elodie; Puttilli, Maria Rita; Chini, Andrea; Devescovi, Giulia; Venturi, Vittorio; Polverari, Annalisa

2017-01-01

The life cycle of bacterial phytopathogens consists of a benign epiphytic phase, during which the bacteria grow in the soil or on the plant surface, and a virulent endophytic phase involving the penetration of host defenses and the colonization of plant tissues. Innovative strategies are urgently required to integrate copper treatments that control the epiphytic phase with complementary tools that control the virulent endophytic phase, thus reducing the quantity of chemicals applied to economically and ecologically acceptable levels. Such strategies include targeted treatments that weaken bacterial pathogens, particularly those inhibiting early infection steps rather than tackling established infections. This chapter describes a reporter gene-based chemical genomic high-throughput screen for the induction of bacterial virulence by plant molecules. Specifically, we describe a chemical genomic screening method to identify agonist and antagonist molecules for the induction of targeted bacterial virulence genes by plant extracts, focusing on the experimental controls required to avoid false positives and thus ensuring the results are reliable and reproducible.

Temporal changes in soil bacterial and archaeal communities with different fertilizers in tea orchards.

PubMed

Wang, Hua; Yang, Shao-hui; Yang, Jing-ping; Lv, Ya-min; Zhao, Xing; Pang, Ji-liang

2014-11-01

It is important to understand the effects of temporal changes in microbial communities in the acidic soils of tea orchards with different fertilizers. A field experiment involving organic fertilizer (OF), chemical fertilizer (CF), and unfertilized control (CK) treatments was arranged to analyze the temporal changes in the bacterial and archaeal communities at bimonthly intervals based on the 16S ribosomal RNA (rRNA) gene using terminal restriction fragment length polymorphism (T-RFLP) profiling. The abundances of total bacteria, total archaea, and selected functional genes (bacterial and archaeal amoA, bacterial narG, nirK, nirS, and nosZ) were determined by quantitative polymerase chain reaction (qPCR). The results indicate that the structures of bacterial and archaeal communities varied significantly with time and fertilization based on changes in the relative abundance of dominant T-RFs. The abundancy of the detected genes changed with time. The total bacteria, total archaea, and archaeal amoA were less abundant in July. The bacterial amoA and denitrifying genes were less abundant in September, except the nirK gene. The OF treatment increased the abundance of the observed genes, while the CF treatment had little influence on them. The soil temperature significantly affected the bacterial and archaeal community structures. The soil moisture was significantly correlated with the abundance of denitrifying genes. Of the soil chemical properties, soil organic carbon was the most important factor and was significantly correlated with the abundance of the detected genes, except the nirK gene. Overall, this study demonstrated the effects of both temporal alteration and organic fertilizer on the structures of microbial communities and the abundance of genes involved in the nitrogen cycle.

Temporal changes in soil bacterial and archaeal communities with different fertilizers in tea orchards* #

PubMed Central

Wang, Hua; Yang, Shao-hui; Yang, Jing-ping; Lv, Ya-min; Zhao, Xing; Pang, Ji-liang

2014-01-01

It is important to understand the effects of temporal changes in microbial communities in the acidic soils of tea orchards with different fertilizers. A field experiment involving organic fertilizer (OF), chemical fertilizer (CF), and unfertilized control (CK) treatments was arranged to analyze the temporal changes in the bacterial and archaeal communities at bimonthly intervals based on the 16S ribosomal RNA (rRNA) gene using terminal restriction fragment length polymorphism (T-RFLP) profiling. The abundances of total bacteria, total archaea, and selected functional genes (bacterial and archaeal amoA, bacterial narG, nirK, nirS, and nosZ) were determined by quantitative polymerase chain reaction (qPCR). The results indicate that the structures of bacterial and archaeal communities varied significantly with time and fertilization based on changes in the relative abundance of dominant T-RFs. The abundancy of the detected genes changed with time. The total bacteria, total archaea, and archaeal amoA were less abundant in July. The bacterial amoA and denitrifying genes were less abundant in September, except the nirK gene. The OF treatment increased the abundance of the observed genes, while the CF treatment had little influence on them. The soil temperature significantly affected the bacterial and archaeal community structures. The soil moisture was significantly correlated with the abundance of denitrifying genes. Of the soil chemical properties, soil organic carbon was the most important factor and was significantly correlated with the abundance of the detected genes, except the nirK gene. Overall, this study demonstrated the effects of both temporal alteration and organic fertilizer on the structures of microbial communities and the abundance of genes involved in the nitrogen cycle. PMID:25367788

Mutant phenotypes for thousands of bacterial genes of unknown function

DOE PAGES

Price, Morgan N.; Wetmore, Kelly M.; Waters, R. Jordan; ...

2018-05-16

One-third of all protein-coding genes from bacterial genomes cannot be annotated with a function. Here, to investigate the functions of these genes, we present genome-wide mutant fitness data from 32 diverse bacteria across dozens of growth conditions. We identified mutant phenotypes for 11,779 protein-coding genes that had not been annotated with a specific function. Many genes could be associated with a specific condition because the gene affected fitness only in that condition, or with another gene in the same bacterium because they had similar mutant phenotypes. Of the poorly annotated genes, 2,316 had associations that have high confidence because theymore » are conserved in other bacteria. By combining these conserved associations with comparative genomics, we identified putative DNA repair proteins; in addition, we propose specific functions for poorly annotated enzymes and transporters and for uncharacterized protein families. Lastly, our study demonstrates the scalability of microbial genetics and its utility for improving gene annotations.« less

Mutant phenotypes for thousands of bacterial genes of unknown function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Price, Morgan N.; Wetmore, Kelly M.; Waters, R. Jordan

One-third of all protein-coding genes from bacterial genomes cannot be annotated with a function. Here, to investigate the functions of these genes, we present genome-wide mutant fitness data from 32 diverse bacteria across dozens of growth conditions. We identified mutant phenotypes for 11,779 protein-coding genes that had not been annotated with a specific function. Many genes could be associated with a specific condition because the gene affected fitness only in that condition, or with another gene in the same bacterium because they had similar mutant phenotypes. Of the poorly annotated genes, 2,316 had associations that have high confidence because theymore » are conserved in other bacteria. By combining these conserved associations with comparative genomics, we identified putative DNA repair proteins; in addition, we propose specific functions for poorly annotated enzymes and transporters and for uncharacterized protein families. Lastly, our study demonstrates the scalability of microbial genetics and its utility for improving gene annotations.« less

Antimicrobial peptide gene induction, involvement of Toll and IMD pathways and defense against bacteria in the red flour beetle, Tribolium castaneum.

PubMed

Yokoi, Kakeru; Koyama, Hiroaki; Minakuchi, Chieka; Tanaka, Toshiharu; Miura, Ken

2012-01-01

Using Tribolium castaneum, we quantitatively investigated the induction of nine antimicrobial peptide (AMP) genes by live gram-negative bacteria (Escherichia coli and Enterobacter cloacae), gram-positive bacteria (Micrococcus luteus and Bacillus subtilis) and the budding yeast (Saccharomyces cerevisiae). Then, five representative AMP genes were selected, and the involvement of the Toll and IMD pathways in their induction by E. coli, M. luteus and S. cerevisiae was examined by utilizing RNA interference of either MyD88 or IMD. Results indicated: Robust and acute induction of three genes by the two bacterial species was mediated mainly by the IMD pathway; slow and sustained induction of one gene by the two bacteria was mediated mainly by the Toll pathway; induction of the remaining one gene by the two bacteria was mediated by both pathways; induction of the five genes by the yeast was mediated by the Toll and/or IMD pathways depending on respective genes. These results suggest that more promiscuous activation and usage of the two pathways may occur in T. castaneum than in Drosophila melanogaster. In addition, the IMD pathway was revealed to dominantly contribute to defense against two bacterial species, gram-negative E. cloacae and gram-positive B. subtilis that possesses DAP-type peptidoglycan.

Genes for all metals--a bacterial view of the periodic table. The 1996 Thom Award Lecture.

PubMed

Silver, S

1998-01-01

Bacterial chromosomes have genes for transport proteins for inorganic nutrient cations and oxyanions, such as NH4+, K+, Mg2+, Co2+, Fe3+, Mn2+, Zn2+ and other trace cations, and PO4(3-), SO4(2-) and less abundant oxyanions. Together these account for perhaps a few hundred genes in many bacteria. Bacterial plasmids encode resistance systems for toxic metal and metalloid ions including Ag+, AsO2-, AsO4(3-), Cd2+, Co2+, CrO4(2-), Cu2+, Hg2+, Ni2+, Pb2+, TeO3(2-), Tl+ and Zn2+. Most resistance systems function by energy-dependent efflux of toxic ions. A few involve enzymatic (mostly redox) transformations. Some of the efflux resistance systems are ATPases and others are chemiosmotic ion/proton exchangers. The Cd(2+)-resistance cation pump of Gram-positive bacteria is membrane P-type ATPase, which has been labeled with 32P from [gamma-32P]ATP and drives ATP-dependent Cd2+ (and Zn2+) transport by membrane vesicles. The genes defective in the human hereditary diseases of copper metabolism, Menkes syndrome and Wilson's disease, encode P-type ATPases that are similar to bacterial cadmium ATPases. The arsenic resistance system transports arsenite [As(III)], alternatively with the ArsB polypeptide functioning as a chemiosmotic efflux transporter or with two polypeptides, ArsB and ArsA, functioning as an ATPase. The third protein of the arsenic resistance system is an enzyme that reduces intracellular arsenate [As(V)] to arsenite [As(III)], the substrate of the efflux system. In Gram-negative cells, a three polypeptide complex functions as a chemiosmotic cation/protein exchanger to efflux Cd2+, Zn2+ and Co2+. This pump consists of an inner membrane (CzcA), an outer membrane (CzcC) and a membrane-spanning (CzcB) protein that function together.

Apolipoprotein gene involved in lipid metabolism

DOEpatents

Rubin, Edward [Berkeley, CA; Pennacchio, Len A [Sebastopol, CA

2007-07-03

Methods and materials for studying the effects of a newly identified human gene, APOAV, and the corresponding mouse gene apoAV. The sequences of the genes are given, and transgenic animals which either contain the gene or have the endogenous gene knocked out are described. In addition, single nucleotide polymorphisms (SNPs) in the gene are described and characterized. It is demonstrated that certain SNPs are associated with diseases involving lipids and triglycerides and other metabolic diseases. These SNPs may be used alone or with SNPs from other genes to study individual risk factors. Methods for intervention in lipid diseases, including the screening of drugs to treat lipid-related or diabetic diseases are also disclosed.

Transcriptome landscape of a bacterial pathogen under plant immunity.

PubMed

Nobori, Tatsuya; Velásquez, André C; Wu, Jingni; Kvitko, Brian H; Kremer, James M; Wang, Yiming; He, Sheng Yang; Tsuda, Kenichi

2018-03-27

Plant pathogens can cause serious diseases that impact global agriculture. The plant innate immunity, when fully activated, can halt pathogen growth in plants. Despite extensive studies into the molecular and genetic bases of plant immunity against pathogens, the influence of plant immunity in global pathogen metabolism to restrict pathogen growth is poorly understood. Here, we developed RNA sequencing pipelines for analyzing bacterial transcriptomes in planta and determined high-resolution transcriptome patterns of the foliar bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana with a total of 27 combinations of plant immunity mutants and bacterial strains. Bacterial transcriptomes were analyzed at 6 h post infection to capture early effects of plant immunity on bacterial processes and to avoid secondary effects caused by different bacterial population densities in planta We identified specific "immune-responsive" bacterial genes and processes, including those that are activated in susceptible plants and suppressed by plant immune activation. Expression patterns of immune-responsive bacterial genes at the early time point were tightly linked to later bacterial growth levels in different host genotypes. Moreover, we found that a bacterial iron acquisition pathway is commonly suppressed by multiple plant immune-signaling pathways. Overexpression of a P. syringae sigma factor gene involved in iron regulation and other processes partially countered bacterial growth restriction during the plant immune response triggered by AvrRpt2. Collectively, this study defines the effects of plant immunity on the transcriptome of a bacterial pathogen and sheds light on the enigmatic mechanisms of bacterial growth inhibition during the plant immune response.

A high-throughput virus-induced gene silencing protocol identifies genes involved in multi-stress tolerance

PubMed Central

2013-01-01

Background Understanding the function of a particular gene under various stresses is important for engineering plants for broad-spectrum stress tolerance. Although virus-induced gene silencing (VIGS) has been used to characterize genes involved in abiotic stress tolerance, currently available gene silencing and stress imposition methodology at the whole plant level is not suitable for high-throughput functional analyses of genes. This demands a robust and reliable methodology for characterizing genes involved in abiotic and multi-stress tolerance. Results Our methodology employs VIGS-based gene silencing in leaf disks combined with simple stress imposition and effect quantification methodologies for easy and faster characterization of genes involved in abiotic and multi-stress tolerance. By subjecting leaf disks from gene-silenced plants to various abiotic stresses and inoculating silenced plants with various pathogens, we show the involvement of several genes for multi-stress tolerance. In addition, we demonstrate that VIGS can be used to characterize genes involved in thermotolerance. Our results also showed the functional relevance of NtEDS1 in abiotic stress, NbRBX1 and NbCTR1 in oxidative stress; NtRAR1 and NtNPR1 in salinity stress; NbSOS1 and NbHSP101 in biotic stress; and NtEDS1, NbETR1, NbWRKY2 and NbMYC2 in thermotolerance. Conclusions In addition to widening the application of VIGS, we developed a robust, easy and high-throughput methodology for functional characterization of genes involved in multi-stress tolerance. PMID:24289810

Bacterial gene abundances as indicators of greenhouse gas emission in soils.

PubMed

Morales, Sergio E; Cosart, Theodore; Holben, William E

2010-06-01

Nitrogen fixing and denitrifying bacteria, respectively, control bulk inputs and outputs of nitrogen in soils, thereby mediating nitrogen-based greenhouse gas emissions in an ecosystem. Molecular techniques were used to evaluate the relative abundances of nitrogen fixing, denitrifying and two numerically dominant ribotypes (based on the > or =97% sequence similarity at the 16S rRNA gene) of bacteria in plots representing 10 agricultural and other land-use practices at the Kellogg biological station long-term ecological research site. Quantification of nitrogen-related functional genes (nitrite reductase, nirS; nitrous oxide reductase, nosZ; and nitrogenase, nifH) as well as two dominant 16S ribotypes (belonging to the phyla Acidobacteria, Thermomicrobia) allowed us to evaluate the hypothesis that microbial community differences are linked to greenhouse gas emissions under different land management practices. Our results suggest that the successional stages of the ecosystem are strongly linked to bacterial functional group abundance, and that the legacy of agricultural practices can be sustained over decades. We also link greenhouse gas emissions with specific compositional responses in the soil bacterial community and assess the use of denitrifying gene abundances as proxies for determining nitrous oxide emissions from soils.

Comprehensive search for accessory proteins encoded with archaeal and bacterial type III CRISPR-cas gene cassettes reveals 39 new cas gene families.

PubMed

Shah, Shiraz A; Alkhnbashi, Omer S; Behler, Juliane; Han, Wenyuan; She, Qunxin; Hess, Wolfgang R; Garrett, Roger A; Backofen, Rolf

2018-06-19

A study was undertaken to identify conserved proteins that are encoded adjacent to cas gene cassettes of Type III CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeats - CRISPR associated) interference modules. Type III modules have been shown to target and degrade dsDNA, ssDNA and ssRNA and are frequently intertwined with cofunctional accessory genes, including genes encoding CRISPR-associated Rossman Fold (CARF) domains. Using a comparative genomics approach, and defining a Type III association score accounting for coevolution and specificity of flanking genes, we identified and classified 39 new Type III associated gene families. Most archaeal and bacterial Type III modules were seen to be flanked by several accessory genes, around half of which did not encode CARF domains and remain of unknown function. Northern blotting and interference assays in Synechocystis confirmed that one particular non-CARF accessory protein family was involved in crRNA maturation. Non-CARF accessory genes were generally diverse, encoding nuclease, helicase, protease, ATPase, transporter and transmembrane domains with some encoding no known domains. We infer that additional families of non-CARF accessory proteins remain to be found. The method employed is scalable for potential application to metagenomic data once automated pipelines for annotation of CRISPR-Cas systems have been developed. All accessory genes found in this study are presented online in a readily accessible and searchable format for researchers to audit their model organism of choice: http://accessory.crispr.dk .

Towards an informative mutant phenotype for every bacterial gene

DOE PAGES

Deutschbauer, Adam; Price, Morgan N.; Wetmore, Kelly M.; ...

2014-08-11

Mutant phenotypes provide strong clues to the functions of the underlying genes and could allow annotation of the millions of sequenced yet uncharacterized bacterial genes. However, it is not known how many genes have a phenotype under laboratory conditions, how many phenotypes are biologically interpretable for predicting gene function, and what experimental conditions are optimal to maximize the number of genes with a phenotype. To address these issues, we measured the mutant fitness of 1,586 genes of the ethanol-producing bacterium Zymomonas mobilis ZM4 across 492 diverse experiments and found statistically significant phenotypes for 89% of all assayed genes. Thus, inmore » Z. mobilis, most genes have a functional consequence under laboratory conditions. We demonstrate that 41% of Z. mobilis genes have both a strong phenotype and a similar fitness pattern (cofitness) to another gene, and are therefore good candidates for functional annotation using mutant fitness. Among 502 poorly characterized Z. mobilis genes, we identified a significant cofitness relationship for 174. For 57 of these genes without a specific functional annotation, we found additional evidence to support the biological significance of these gene-gene associations, and in 33 instances, we were able to predict specific physiological or biochemical roles for the poorly characterized genes. Last, we identified a set of 79 diverse mutant fitness experiments in Z. mobilis that are nearly as biologically informative as the entire set of 492 experiments. Therefore, our work provides a blueprint for the functional annotation of diverse bacteria using mutant fitness.« less

Bacterial enzymes involved in lignin degradation.

PubMed

de Gonzalo, Gonzalo; Colpa, Dana I; Habib, Mohamed H M; Fraaije, Marco W

2016-10-20

Lignin forms a large part of plant biomass. It is a highly heterogeneous polymer of 4-hydroxyphenylpropanoid units and is embedded within polysaccharide polymers forming lignocellulose. Lignin provides strength and rigidity to plants and is rather resilient towards degradation. To improve the (bio)processing of lignocellulosic feedstocks, more effective degradation methods of lignin are in demand. Nature has found ways to fully degrade lignin through the production of dedicated ligninolytic enzyme systems. While such enzymes have been well thoroughly studied for ligninolytic fungi, only in recent years biochemical studies on bacterial enzymes capable of lignin modification have intensified. This has revealed several types of enzymes available to bacteria that enable them to act on lignin. Two major classes of bacterial lignin-modifying enzymes are DyP-type peroxidases and laccases. Yet, recently also several other bacterial enzymes have been discovered that seem to play a role in lignin modifications. In the present review, we provide an overview of recent advances in the identification and use of bacterial enzymes acting on lignin or lignin-derived products. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

Diversity of Two-Domain Laccase-Like Multicopper Oxidase Genes in Streptomyces spp.: Identification of Genes Potentially Involved in Extracellular Activities and Lignocellulose Degradation during Composting of Agricultural Waste

PubMed Central

Lu, Lunhui; Zhang, Jiachao; Chen, Anwei; Chen, Ming; Jiang, Min; Yuan, Yujie; Wu, Haipeng; Lai, Mingyong; He, Yibin

2014-01-01

Traditional three-domain fungal and bacterial laccases have been extensively studied for their significance in various biotechnological applications. Growing molecular evidence points to a wide occurrence of more recently recognized two-domain laccase-like multicopper oxidase (LMCO) genes in Streptomyces spp. However, the current knowledge about their ecological role and distribution in natural or artificial ecosystems is insufficient. The aim of this study was to investigate the diversity and composition of Streptomyces two-domain LMCO genes in agricultural waste composting, which will contribute to the understanding of the ecological function of Streptomyces two-domain LMCOs with potential extracellular activity and ligninolytic capacity. A new specific PCR primer pair was designed to target the two conserved copper binding regions of Streptomyces two-domain LMCO genes. The obtained sequences mainly clustered with Streptomyces coelicolor, Streptomyces violaceusniger, and Streptomyces griseus. Gene libraries retrieved from six composting samples revealed high diversity and a rapid succession of Streptomyces two-domain LMCO genes during composting. The obtained sequence types cluster in 8 distinct clades, most of which are homologous with Streptomyces two-domain LMCO genes, but the sequences of clades III and VIII do not match with any reference sequence of known streptomycetes. Both lignocellulose degradation rates and phenol oxidase activity at pH 8.0 in the composting process were found to be positively associated with the abundance of Streptomyces two-domain LMCO genes. These observations provide important clues that Streptomyces two-domain LMCOs are potentially involved in bacterial extracellular phenol oxidase activities and lignocellulose breakdown during agricultural waste composting. PMID:24657870

Simultaneous amplification of two bacterial genes: more reliable method of Helicobacter pylori detection in microbial rich dental plaque samples.

PubMed

Chaudhry, Saima; Idrees, Muhammad; Izhar, Mateen; Butt, Arshad Kamal; Khan, Ayyaz Ali

2011-01-01

Polymerase Chain reaction (PCR) assay is considered superior to other methods for detection of Helicobacter pylori (H. pylori) in oral cavity; however, it also has limitations when sample under study is microbial rich dental plaque. The type of gene targeted and number of primers used for bacterial detection in dental plaque samples can have a significant effect on the results obtained as there are a number of closely related bacterial species residing in plaque biofilm. Also due to high recombination rate of H. pylori some of the genes might be down regulated or absent. The present study was conducted to determine the frequency of H. pylori colonization of dental plaque by simultaneously amplifying two genes of the bacterium. One hundred dental plaque specimens were collected from dyspeptic patients before their upper gastrointestinal endoscopy and presence of H. pylori was determined through PCR assay using primers targeting two different genes of the bacterium. Eighty-nine of the 100 samples were included in final analysis. With simultaneous amplification of two bacterial genes 51.6% of the dental plaque samples were positive for H. pylori while this prevalence increased to 73% when only one gene amplification was used for bacterial identification. Detection of H. pylori in dental plaque samples is more reliable when two genes of the bacterium are simultaneously amplified as compared to one gene amplification only.

Genomic features of bacterial adaptation to plants

PubMed Central

Levy, Asaf; Gonzalez, Isai Salas; Mittelviefhaus, Maximilian; Clingenpeel, Scott; Paredes, Sur Herrera; Miao, Jiamin; Wang, Kunru; Devescovi, Giulia; Stillman, Kyra; Monteiro, Freddy; Alvarez, Bryan Rangel; Lundberg, Derek S.; Lu, Tse-Yuan; Lebeis, Sarah; Jin, Zhao; McDonald, Meredith; Klein, Andrew P.; Feltcher, Meghan E.; del Rio, Tijana Glavina; Grant, Sarah R.; Doty, Sharon L.; Ley, Ruth E.; Zhao, Bingyu; Venturi, Vittorio; Pelletier, Dale A.; Vorholt, Julia A.; Tringe, Susannah G.; Woyke, Tanja; Dangl, Jeffery L.

2017-01-01

Plants intimately associate with diverse bacteria. Plant-associated (PA) bacteria have ostensibly evolved genes enabling adaptation to the plant environment. However, the identities of such genes are mostly unknown and their functions are poorly characterized. We sequenced 484 genomes of bacterial isolates from roots of Brassicaceae, poplar, and maize. We then compared 3837 bacterial genomes to identify thousands of PA gene clusters. Genomes of PA bacteria encode more carbohydrate metabolism functions and fewer mobile elements than related non-plant associated genomes. We experimentally validated candidates from two sets of PA genes, one involved in plant colonization, the other serving in microbe-microbe competition between PA bacteria. We also identified 64 PA protein domains that potentially mimic plant domains; some are shared with PA fungi and oomycetes. This work expands the genome-based understanding of plant-microbe interactions and provides leads for efficient and sustainable agriculture through microbiome engineering. PMID:29255260

Gene regulation mediates host specificity of a bacterial pathogen.

PubMed

Killiny, Nabil; Almeida, Rodrigo P P

2011-12-01

Many bacterial plant pathogens have a gene-for-gene relationship that determines host specificity. However, there are pathogens such as the xylem-limited bacterium Xylella fastidiosa that do not carry genes considered essential for the gene-for-gene model, such as those coding for a type III secretion system and effector molecules. Nevertheless, X. fastidiosa subspecies are host specific. A comparison of symptom development and host colonization after infection of plants with several mutant strains in two hosts, grapevines and almonds, indicated that X. fastidiosa virulence mechanisms are similar in those plants. Thus, we tested if modification of gene regulation patterns, by affecting the production of a cell-cell signalling molecule (DSF), impacted host specificity in X. fastidiosa. Results show that disruption of the rpfF locus, required for DSF synthesis, in a strain incapable of causing disease in grapevines, leads to symptom development in that host. These data are indicative that the core machinery required for the colonization of grapevines is present in that strain, and that changes in gene regulation alone can lead X. fastidiosa to exploit a novel host. The study of the evolution and mechanisms of host specificity mediated by gene regulation at the genome level could lead to important insights on the emergence of new diseases. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Mountain pine beetles colonizing historical and naive host trees are associated with a bacterial community highly enriched in genes contributing to terpene metabolism.

PubMed

Adams, Aaron S; Aylward, Frank O; Adams, Sandye M; Erbilgin, Nadir; Aukema, Brian H; Currie, Cameron R; Suen, Garret; Raffa, Kenneth F

2013-06-01

The mountain pine beetle, Dendroctonus ponderosae, is a subcortical herbivore native to western North America that can kill healthy conifers by overcoming host tree defenses, which consist largely of high terpene concentrations. The mechanisms by which these beetles contend with toxic compounds are not well understood. Here, we explore a component of the hypothesis that beetle-associated bacterial symbionts contribute to the ability of D. ponderosae to overcome tree defenses by assisting with terpene detoxification. Such symbionts may facilitate host tree transitions during range expansions currently being driven by climate change. For example, this insect has recently breached the historical geophysical barrier of the Canadian Rocky Mountains, providing access to näive tree hosts and unprecedented connectivity to eastern forests. We use culture-independent techniques to describe the bacterial community associated with D. ponderosae beetles and their galleries from their historical host, Pinus contorta, and their more recent host, hybrid P. contorta-Pinus banksiana. We show that these communities are enriched with genes involved in terpene degradation compared with other plant biomass-processing microbial communities. These pine beetle microbial communities are dominated by members of the genera Pseudomonas, Rahnella, Serratia, and Burkholderia, and the majority of genes involved in terpene degradation belong to these genera. Our work provides the first metagenome of bacterial communities associated with a bark beetle and is consistent with a potential microbial contribution to detoxification of tree defenses needed to survive the subcortical environment.

Assessment of Bacterial bph Gene in Amazonian Dark Earth and Their Adjacent Soils

PubMed Central

Brossi, Maria Julia de Lima; Mendes, Lucas William; Germano, Mariana Gomes; Lima, Amanda Barbosa; Tsai, Siu Mui

2014-01-01

Amazonian Anthrosols are known to harbour distinct and highly diverse microbial communities. As most of the current assessments of these communities are based on taxonomic profiles, the functional gene structure of these communities, such as those responsible for key steps in the carbon cycle, mostly remain elusive. To gain insights into the diversity of catabolic genes involved in the degradation of hydrocarbons in anthropogenic horizons, we analysed the bacterial bph gene community structure, composition and abundance using T-RFLP, 454-pyrosequencing and quantitative PCR essays, respectively. Soil samples were collected in two Brazilian Amazon Dark Earth (ADE) sites and at their corresponding non-anthropogenic adjacent soils (ADJ), under two different land use systems, secondary forest (SF) and manioc cultivation (M). Redundancy analysis of T-RFLP data revealed differences in bph gene structure according to both soil type and land use. Chemical properties of ADE soils, such as high organic carbon and organic matter, as well as effective cation exchange capacity and pH, were significantly correlated with the structure of bph communities. Also, the taxonomic affiliation of bph gene sequences revealed the segregation of community composition according to the soil type. Sequences at ADE sites were mostly affiliated to aromatic hydrocarbon degraders belonging to the genera Streptomyces, Sphingomonas, Rhodococcus, Mycobacterium, Conexibacter and Burkholderia. In both land use sites, shannon's diversity indices based on the bph gene data were higher in ADE than ADJ soils. Collectively, our findings provide evidence that specific properties in ADE soils shape the structure and composition of bph communities. These results provide a basis for further investigations focusing on the bio-exploration of novel enzymes with potential use in the biotechnology/biodegradation industry. PMID:24927167

Assessment of bacterial bph gene in Amazonian dark earth and their adjacent soils.

PubMed

Brossi, Maria Julia de Lima; Mendes, Lucas William; Germano, Mariana Gomes; Lima, Amanda Barbosa; Tsai, Siu Mui

2014-01-01

Amazonian Anthrosols are known to harbour distinct and highly diverse microbial communities. As most of the current assessments of these communities are based on taxonomic profiles, the functional gene structure of these communities, such as those responsible for key steps in the carbon cycle, mostly remain elusive. To gain insights into the diversity of catabolic genes involved in the degradation of hydrocarbons in anthropogenic horizons, we analysed the bacterial bph gene community structure, composition and abundance using T-RFLP, 454-pyrosequencing and quantitative PCR essays, respectively. Soil samples were collected in two Brazilian Amazon Dark Earth (ADE) sites and at their corresponding non-anthropogenic adjacent soils (ADJ), under two different land use systems, secondary forest (SF) and manioc cultivation (M). Redundancy analysis of T-RFLP data revealed differences in bph gene structure according to both soil type and land use. Chemical properties of ADE soils, such as high organic carbon and organic matter, as well as effective cation exchange capacity and pH, were significantly correlated with the structure of bph communities. Also, the taxonomic affiliation of bph gene sequences revealed the segregation of community composition according to the soil type. Sequences at ADE sites were mostly affiliated to aromatic hydrocarbon degraders belonging to the genera Streptomyces, Sphingomonas, Rhodococcus, Mycobacterium, Conexibacter and Burkholderia. In both land use sites, shannon's diversity indices based on the bph gene data were higher in ADE than ADJ soils. Collectively, our findings provide evidence that specific properties in ADE soils shape the structure and composition of bph communities. These results provide a basis for further investigations focusing on the bio-exploration of novel enzymes with potential use in the biotechnology/biodegradation industry.

Bacterial community structure and abundances of antibiotic resistance genes in heavy metals contaminated agricultural soil.

PubMed

Zhang, Fengli; Zhao, Xiaoxue; Li, Qingbo; Liu, Jia; Ding, Jizhe; Wu, Huiying; Zhao, Zongsheng; Ba, Yue; Cheng, Xuemin; Cui, Liuxin; Li, Hongping; Zhu, Jingyuan

2018-04-01

Soil contamination with heavy metals is a worldwide problem especially in China. The interrelation of soil bacterial community structure, antibiotic resistance genes, and heavy metal contamination in soil is still unclear. Here, seven agricultural areas (G1-G7) with heavy metal contamination were sampled with different distances (741 to 2556 m) to the factory. Denaturing gradient gel electrophoresis (DGGE) and Shannon index were used to analyze bacterial community diversity. Real-time fluorescence quantitative PCR was used to detect the relative abundance of ARGs sul1, sul2, tetA, tetM, tetW, one mobile genetic elements (MGE) inti1. Results showed that all samples were polluted by Cadmium (Cd), and some of them were polluted by lead (Pb), mercury (Hg), arsenic (As), copper (Cu), and zinc (Zn). DGGE showed that the most abundant bacterial species were found in G7 with the lightest heavy metal contamination. The results of the principal component analysis and clustering analysis both showed that G7 could not be classified with other samples. The relative abundance of sul1 was correlated with Cu, Zn concentration. Gene sul2 are positively related with total phosphorus, and tetM was associated with organic matter. Total gene abundances and relative abundance of inti1 both correlated with organic matter. Redundancy analysis showed that Zn and sul2 were significantly related with bacterial community structure. Together, our results indicate a complex linkage between soil heavy metal concentration, bacterial community composition, and some global disseminated ARG abundance.

Analysis of host response to bacterial infection using error model based gene expression microarray experiments

PubMed Central

Stekel, Dov J.; Sarti, Donatella; Trevino, Victor; Zhang, Lihong; Salmon, Mike; Buckley, Chris D.; Stevens, Mark; Pallen, Mark J.; Penn, Charles; Falciani, Francesco

2005-01-01

A key step in the analysis of microarray data is the selection of genes that are differentially expressed. Ideally, such experiments should be properly replicated in order to infer both technical and biological variability, and the data should be subjected to rigorous hypothesis tests to identify the differentially expressed genes. However, in microarray experiments involving the analysis of very large numbers of biological samples, replication is not always practical. Therefore, there is a need for a method to select differentially expressed genes in a rational way from insufficiently replicated data. In this paper, we describe a simple method that uses bootstrapping to generate an error model from a replicated pilot study that can be used to identify differentially expressed genes in subsequent large-scale studies on the same platform, but in which there may be no replicated arrays. The method builds a stratified error model that includes array-to-array variability, feature-to-feature variability and the dependence of error on signal intensity. We apply this model to the characterization of the host response in a model of bacterial infection of human intestinal epithelial cells. We demonstrate the effectiveness of error model based microarray experiments and propose this as a general strategy for a microarray-based screening of large collections of biological samples. PMID:15800204

Identification of Bacterial Factors Involved in Type 1 Fimbria Expression using an Escherichia coli K12 Proteome Chip*

PubMed Central

Chen, Yi-Wen; Teng, Ching-Hao; Ho, Yu-Hsuan; Jessica Ho, Tien Yu; Huang, Wen-Chun; Hashimoto, Masayuki; Chiang, I-Yuan; Chen, Chien-Sheng

2014-01-01

Type 1 fimbriae are filamentous structures on Escherichia coli. These structures are important adherence factors. Because binding to the host cells is the first step of infection, type 1 fimbria is an important virulence factor of pathogenic E. coli. Expression of type 1 fimbria is regulated by a phase variation in which each individual bacterium can alternate between fimbriated (phase-ON) and nonfimbriated (phase-OFF) states. The phase variation is regulated by the flipping of the 314-bp fimS fragment, which contains the promoter driving the expression of the genes required for the synthesis of type 1 fimbria. Thus, the bacterial proteins able to interact with fimS are likely to be involved in regulating the expression of type 1 fimbria. To identify novel type 1 fimbria-regulating factors, we used an E. coli K12 proteome chip to screen for the bacterial factors able to interact with a 602-bp DNA fragment containing fimS and its adjacent regions. The Spr protein was identified by the proteome chip-based screening and further confirmed to be able to interact with fimS by electrophoretic mobility shift assay. Deletion of spr in the neonatal meningitis E. coli strain RS218 significantly increased the ratio of the bacterial colonies that contained the type 1 fimbria phase-ON cells on agar plates. In addition, Spr interfered with the interactions of fimS with the site-specific recombinases, FimB and FimE, which are responsible for mediating the flipping of fimS. These results suggest that Spr is involved in the regulation of type 1 fimbria expression through direct interaction with the invertible element fimS. These findings facilitate our understanding of the regulation of type 1 fimbria. PMID:24692643

Transport of Magnesium by a Bacterial Nramp-Related Gene

PubMed Central

Rodionov, Dmitry A.; Freedman, Benjamin G.; Senger, Ryan S.; Winkler, Wade C.

2014-01-01

Magnesium is an essential divalent metal that serves many cellular functions. While most divalent cations are maintained at relatively low intracellular concentrations, magnesium is maintained at a higher level (∼0.5–2.0 mM). Three families of transport proteins were previously identified for magnesium import: CorA, MgtE, and MgtA/MgtB P-type ATPases. In the current study, we find that expression of a bacterial protein unrelated to these transporters can fully restore growth to a bacterial mutant that lacks known magnesium transporters, suggesting it is a new importer for magnesium. We demonstrate that this transport activity is likely to be specific rather than resulting from substrate promiscuity because the proteins are incapable of manganese import. This magnesium transport protein is distantly related to the Nramp family of proteins, which have been shown to transport divalent cations but have never been shown to recognize magnesium. We also find gene expression of the new magnesium transporter to be controlled by a magnesium-sensing riboswitch. Importantly, we find additional examples of riboswitch-regulated homologues, suggesting that they are a frequent occurrence in bacteria. Therefore, our aggregate data discover a new and perhaps broadly important path for magnesium import and highlight how identification of riboswitch RNAs can help shed light on new, and sometimes unexpected, functions of their downstream genes. PMID:24968120

Production of Phloroglucinol, a Platform Chemical, in Arabidopsis using a Bacterial Gene.

PubMed

Abdel-Ghany, Salah E; Day, Irene; Heuberger, Adam L; Broeckling, Corey D; Reddy, Anireddy S N

2016-12-07

Phloroglucinol (1,3,5-trihydroxybenzene; PG) and its derivatives are phenolic compounds that are used for various industrial applications. Current methods to synthesize PG are not sustainable due to the requirement for carbon-based precursors and co-production of toxic byproducts. Here, we describe a more sustainable production of PG using plants expressing a native bacterial or a codon-optimized synthetic PhlD targeted to either the cytosol or chloroplasts. Transgenic lines were analyzed for the production of PG using gas and liquid chromatography coupled to mass spectroscopy. Phloroglucinol was produced in all transgenic lines and the line with the highest PhlD transcript level showed the most accumulation of PG. Over 80% of the produced PG was glycosylated to phlorin. Arabidopsis leaves have the machinery to glycosylate PG to form phlorin, which can be hydrolyzed enzymatically to produce PG. Furthermore, the metabolic profile of plants with PhlD in either the cytosol or chloroplasts was altered. Our results provide evidence that plants can be engineered to produce PG using a bacterial gene. Phytoproduction of PG using a bacterial gene paves the way for further genetic manipulations to enhance the level of PG with implications for the commercial production of this important platform chemical in plants.

Seasonal Changes in Bacterial and Archaeal Gene Expression Patterns across Salinity Gradients in the Columbia River Coastal Margin

PubMed Central

Smith, Maria W.; Herfort, Lydie; Tyrol, Kaitlin; Suciu, Dominic; Campbell, Victoria; Crump, Byron C.; Peterson, Tawnya D.; Zuber, Peter; Baptista, Antonio M.; Simon, Holly M.

2010-01-01

Through their metabolic activities, microbial populations mediate the impact of high gradient regions on ecological function and productivity of the highly dynamic Columbia River coastal margin (CRCM). A 2226-probe oligonucleotide DNA microarray was developed to investigate expression patterns for microbial genes involved in nitrogen and carbon metabolism in the CRCM. Initial experiments with the environmental microarrays were directed toward validation of the platform and yielded high reproducibility in multiple tests. Bioinformatic and experimental validation also indicated that >85% of the microarray probes were specific for their corresponding target genes and for a few homologs within the same microbial family. The validated probe set was used to query gene expression responses by microbial assemblages to environmental variability. Sixty-four samples from the river, estuary, plume, and adjacent ocean were collected in different seasons and analyzed to correlate the measured variability in chemical, physical and biological water parameters to differences in global gene expression profiles. The method produced robust seasonal profiles corresponding to pre-freshet spring (April) and late summer (August). Overall relative gene expression was high in both seasons and was consistent with high microbial abundance measured by total RNA, heterotrophic bacterial production, and chlorophyll a. Both seasonal patterns involved large numbers of genes that were highly expressed relative to background, yet each produced very different gene expression profiles. April patterns revealed high differential gene expression in the coastal margin samples (estuary, plume and adjacent ocean) relative to freshwater, while little differential gene expression was observed along the river-to-ocean transition in August. Microbial gene expression profiles appeared to relate, in part, to seasonal differences in nutrient availability and potential resource competition. Furthermore, our results

Functional characterization of two SOS-regulated genes involved in mitomycin C resistance in Caulobacter crescentus.

PubMed

Lopes-Kulishev, Carina O; Alves, Ingrid R; Valencia, Estela Y; Pidhirnyj, María I; Fernández-Silva, Frank S; Rodrigues, Ticiane R; Guzzo, Cristiane R; Galhardo, Rodrigo S

2015-09-01

The SOS response is a universal bacterial regulon involved in the cellular response to DNA damage and other forms of stress. In Caulobacter crescentus, previous work has identified a plethora of genes that are part of the SOS regulon, but the biological roles of several of them remain to be determined. In this study, we report that two genes, hereafter named mmcA and mmcB, are involved in the defense against DNA damage caused by mitomycin C (MMC), but not against lesions induced by other common DNA damaging agents, such as UVC light, methyl methanesulfonate (MMS) and hydrogen peroxide. mmcA is a conserved gene that encodes a member of the glyoxalases/dioxygenases protein family, and acts independently of known DNA repair pathways. On the other hand, epistasis analysis showed that mmcB acts in the same pathway as imuC (dnaE2), and is required specifically for MMC-induced mutagenesis, but not for that induced by UV light, suggesting a role for MmcB in translesion synthesis-dependent repair of MMC damage. We show that the lack of MMC-induced mutability in the mmcB strain is not caused by lack of proper SOS induction of the imuABC operon, involved in translesion synthesis (TLS) in C. crescentus. Based on this data and on structural analysis of a close homolog, we propose that MmcB is an endonuclease which creates substrates for ImuABC-mediated TLS patches. Copyright © 2015 Elsevier B.V. All rights reserved.

CRISPR Perturbation of Gene Expression Alters Bacterial Fitness under Stress and Reveals Underlying Epistatic Constraints.

PubMed

Otoupal, Peter B; Erickson, Keesha E; Escalas-Bordoy, Antoni; Chatterjee, Anushree

2017-01-20

The evolution of antibiotic resistance has engendered an impending global health crisis that necessitates a greater understanding of how resistance emerges. The impact of nongenetic factors and how they influence the evolution of resistance is a largely unexplored area of research. Here we present a novel application of CRISPR-Cas9 technology for investigating how gene expression governs the adaptive pathways available to bacteria during the evolution of resistance. We examine the impact of gene expression changes on bacterial adaptation by constructing a library of deactivated CRISPR-Cas9 synthetic devices to tune the expression of a set of stress-response genes in Escherichia coli. We show that artificially inducing perturbations in gene expression imparts significant synthetic control over fitness and growth during stress exposure. We present evidence that these impacts are reversible; strains with synthetically perturbed gene expression regained wild-type growth phenotypes upon stress removal, while maintaining divergent growth characteristics under stress. Furthermore, we demonstrate a prevailing trend toward negative epistatic interactions when multiple gene perturbations are combined simultaneously, thereby posing an intrinsic constraint on gene expression underlying adaptive trajectories. Together, these results emphasize how CRISPR-Cas9 can be employed to engineer gene expression changes that shape bacterial adaptation, and present a novel approach to synthetically control the evolution of antimicrobial resistance.

Genetic analysis of a bacterial genetic exchange element: The gene transfer agent of Rhodobacter capsulatus

PubMed Central

Lang, Andrew S.; Beatty, J. T.

2000-01-01

An unusual system of genetic exchange exists in the purple nonsulfur bacterium Rhodobacter capsulatus. DNA transmission is mediated by a small bacteriophage-like particle called the gene transfer agent (GTA) that transfers random 4.5-kb segments of the producing cell's genome to recipient cells, where allelic replacement occurs. This paper presents the results of gene cloning, analysis, and mutagenesis experiments that show that GTA resembles a defective prophage related to bacteriophages from diverse genera of bacteria, which has been adopted by R. capsulatus for genetic exchange. A pair of cellular proteins, CckA and CtrA, appear to constitute part of a sensor kinase/response regulator signaling pathway that is required for expression of GTA structural genes. This signaling pathway controls growth-phase-dependent regulation of GTA gene messages, yielding maximal gene expression in the stationary phase. We suggest that GTA is an ancient prophage remnant that has evolved in concert with the bacterial genome, resulting in a genetic exchange process controlled by the bacterial cell. PMID:10639170

Phylogeographic reconstruction of a bacterial species with high levels of lateral gene transfer

USGS Publications Warehouse

Pearson, T.; Giffard, P.; Beckstrom-Sternberg, S.; Auerbach, R.; Hornstra, H.; Tuanyok, A.; Price, E.P.; Glass, M.B.; Leadem, B.; Beckstrom-Sternberg, J. S.; Allan, G.J.; Foster, J.T.; Wagner, D.M.; Okinaka, R.T.; Sim, S.H.; Pearson, O.; Wu, Z.; Chang, J.; Kaul, R.; Hoffmaster, A.R.; Brettin, T.S.; Robison, R.A.; Mayo, M.; Gee, J.E.; Tan, P.; Currie, B.J.; Keim, P.

2009-01-01

Background: Phylogeographic reconstruction of some bacterial populations is hindered by low diversity coupled with high levels of lateral gene transfer. A comparison of recombination levels and diversity at seven housekeeping genes for eleven bacterial species, most of which are commonly cited as having high levels of lateral gene transfer shows that the relative contributions of homologous recombination versus mutation for Burkholderia pseudomallei is over two times higher than for Streptococcus pneumoniae and is thus the highest value yet reported in bacteria. Despite the potential for homologous recombination to increase diversity, B. pseudomallei exhibits a relative lack of diversity at these loci. In these situations, whole genome genotyping of orthologous shared single nucleotide polymorphism loci, discovered using next generation sequencing technologies, can provide very large data sets capable of estimating core phylogenetic relationships. We compared and searched 43 whole genome sequences of B. pseudomallei and its closest relatives for single nucleotide polymorphisms in orthologous shared regions to use in phylogenetic reconstruction. Results: Bayesian phylogenetic analyses of >14,000 single nucleotide polymorphisms yielded completely resolved trees for these 43 strains with high levels of statistical support. These results enable a better understanding of a separate analysis of population differentiation among >1,700 B. pseudomallei isolates as defined by sequence data from seven housekeeping genes. We analyzed this larger data set for population structure and allele sharing that can be attributed to lateral gene transfer. Our results suggest that despite an almost panmictic population, we can detect two distinct populations of B. pseudomallei that conform to biogeographic patterns found in many plant and animal species. That is, separation along Wallace's Line, a biogeographic boundary between Southeast Asia and Australia. Conclusion: We describe an

Differential Gene Expression by Lactobacillus plantarum WCFS1 in Response to Phenolic Compounds Reveals New Genes Involved in Tannin Degradation.

PubMed

Reverón, Inés; Jiménez, Natalia; Curiel, José Antonio; Peñas, Elena; López de Felipe, Félix; de Las Rivas, Blanca; Muñoz, Rosario

2017-04-01

Lactobacillus plantarum is a lactic acid bacterium that can degrade food tannins by the successive action of tannase and gallate decarboxylase enzymes. In the L. plantarum genome, the gene encoding the catalytic subunit of gallate decarboxylase ( lpdC , or lp_2945 ) is only 6.5 kb distant from the gene encoding inducible tannase ( L. plantarum tanB [ tanB Lp ], or lp_2956 ). This genomic context suggests concomitant activity and regulation of both enzymatic activities. Reverse transcription analysis revealed that subunits B ( lpdB , or lp_0271 ) and D ( lpdD , or lp_0272 ) of the gallate decarboxylase are cotranscribed, whereas subunit C ( lpdC , or lp_2945 ) is cotranscribed with a gene encoding a transport protein ( gacP , or lp_2943 ). In contrast, the tannase gene is transcribed as a monocistronic mRNA. Investigation of knockout mutations of genes located in this chromosomal region indicated that only mutants of the gallate decarboxylase (subunits B and C), tannase, GacP transport protein, and TanR transcriptional regulator ( lp_2942 ) genes exhibited altered tannin metabolism. The expression profile of genes involved in tannin metabolism was also analyzed in these mutants in the presence of methyl gallate and gallic acid. It is noteworthy that inactivation of tanR suppresses the induction of all genes overexpressed in the presence of methyl gallate and gallic acid. This transcriptional regulator was also induced in the presence of other phenolic compounds, such as kaempferol and myricetin. This study complements the catalog of L. plantarum expression profiles responsive to phenolic compounds, which enable this bacterium to adapt to a plant food environment. IMPORTANCE Lactobacillus plantarum is a bacterial species frequently found in the fermentation of vegetables when tannins are present. L. plantarum strains degrade tannins to the less-toxic pyrogallol by the successive action of tannase and gallate decarboxylase enzymes. The genes encoding these enzymes are

Differential Gene Expression by Lactobacillus plantarum WCFS1 in Response to Phenolic Compounds Reveals New Genes Involved in Tannin Degradation

PubMed Central

Reverón, Inés; Jiménez, Natalia; Curiel, José Antonio; Peñas, Elena; López de Felipe, Félix; de las Rivas, Blanca

2017-01-01

ABSTRACT Lactobacillus plantarum is a lactic acid bacterium that can degrade food tannins by the successive action of tannase and gallate decarboxylase enzymes. In the L. plantarum genome, the gene encoding the catalytic subunit of gallate decarboxylase (lpdC, or lp_2945) is only 6.5 kb distant from the gene encoding inducible tannase (L. plantarum tanB [tanBLp], or lp_2956). This genomic context suggests concomitant activity and regulation of both enzymatic activities. Reverse transcription analysis revealed that subunits B (lpdB, or lp_0271) and D (lpdD, or lp_0272) of the gallate decarboxylase are cotranscribed, whereas subunit C (lpdC, or lp_2945) is cotranscribed with a gene encoding a transport protein (gacP, or lp_2943). In contrast, the tannase gene is transcribed as a monocistronic mRNA. Investigation of knockout mutations of genes located in this chromosomal region indicated that only mutants of the gallate decarboxylase (subunits B and C), tannase, GacP transport protein, and TanR transcriptional regulator (lp_2942) genes exhibited altered tannin metabolism. The expression profile of genes involved in tannin metabolism was also analyzed in these mutants in the presence of methyl gallate and gallic acid. It is noteworthy that inactivation of tanR suppresses the induction of all genes overexpressed in the presence of methyl gallate and gallic acid. This transcriptional regulator was also induced in the presence of other phenolic compounds, such as kaempferol and myricetin. This study complements the catalog of L. plantarum expression profiles responsive to phenolic compounds, which enable this bacterium to adapt to a plant food environment. IMPORTANCE Lactobacillus plantarum is a bacterial species frequently found in the fermentation of vegetables when tannins are present. L. plantarum strains degrade tannins to the less-toxic pyrogallol by the successive action of tannase and gallate decarboxylase enzymes. The genes encoding these enzymes are located

Suitability of partial 16S ribosomal RNA gene sequence analysis for the identification of dangerous bacterial pathogens.

PubMed

Ruppitsch, W; Stöger, A; Indra, A; Grif, K; Schabereiter-Gurtner, C; Hirschl, A; Allerberger, F

2007-03-01

In a bioterrorism event a rapid tool is needed to identify relevant dangerous bacteria. The aim of the study was to assess the usefulness of partial 16S rRNA gene sequence analysis and the suitability of diverse databases for identifying dangerous bacterial pathogens. For rapid identification purposes a 500-bp fragment of the 16S rRNA gene of 28 isolates comprising Bacillus anthracis, Brucella melitensis, Burkholderia mallei, Burkholderia pseudomallei, Francisella tularensis, Yersinia pestis, and eight genus-related and unrelated control strains was amplified and sequenced. The obtained sequence data were submitted to three public and two commercial sequence databases for species identification. The most frequent reason for incorrect identification was the lack of the respective 16S rRNA gene sequences in the database. Sequence analysis of a 500-bp 16S rDNA fragment allows the rapid identification of dangerous bacterial species. However, for discrimination of closely related species sequencing of the entire 16S rRNA gene, additional sequencing of the 23S rRNA gene or sequencing of the 16S-23S rRNA intergenic spacer is essential. This work provides comprehensive information on the suitability of partial 16S rDNA analysis and diverse databases for rapid and accurate identification of dangerous bacterial pathogens.

Bacterial host and reporter gene optimization for genetically encoded whole cell biosensors.

PubMed

Brutesco, Catherine; Prévéral, Sandra; Escoffier, Camille; Descamps, Elodie C T; Prudent, Elsa; Cayron, Julien; Dumas, Louis; Ricquebourg, Manon; Adryanczyk-Perrier, Géraldine; de Groot, Arjan; Garcia, Daniel; Rodrigue, Agnès; Pignol, David; Ginet, Nicolas

2017-01-01

Whole-cell biosensors based on reporter genes allow detection of toxic metals in water with high selectivity and sensitivity under laboratory conditions; nevertheless, their transfer to a commercial inline water analyzer requires specific adaptation and optimization to field conditions as well as economical considerations. We focused here on both the influence of the bacterial host and the choice of the reporter gene by following the responses of global toxicity biosensors based on constitutive bacterial promoters as well as arsenite biosensors based on the arsenite-inducible P ars promoter. We observed important variations of the bioluminescence emission levels in five different Escherichia coli strains harboring two different lux-based biosensors, suggesting that the best host strain has to be empirically selected for each new biosensor under construction. We also investigated the bioluminescence reporter gene system transferred into Deinococcus deserti, an environmental, desiccation- and radiation-tolerant bacterium that would reduce the manufacturing costs of bacterial biosensors for commercial water analyzers and open the field of biodetection in radioactive environments. We thus successfully obtained a cell survival biosensor and a metal biosensor able to detect a concentration as low as 100 nM of arsenite in D. deserti. We demonstrated that the arsenite biosensor resisted desiccation and remained functional after 7 days stored in air-dried D. deserti cells. We also report here the use of a new near-infrared (NIR) fluorescent reporter candidate, a bacteriophytochrome from the magnetotactic bacterium Magnetospirillum magneticum AMB-1, which showed a NIR fluorescent signal that remained optimal despite increasing sample turbidity, while in similar conditions, a drastic loss of the lux-based biosensors signal was observed.

Gene and transcript abundances of bacterial type III secretion systems from the rumen microbiome are correlated with methane yield in sheep.

PubMed

Kamke, Janine; Soni, Priya; Li, Yang; Ganesh, Siva; Kelly, William J; Leahy, Sinead C; Shi, Weibing; Froula, Jeff; Rubin, Edward M; Attwood, Graeme T

2017-08-08

Ruminants are important contributors to global methane emissions via microbial fermentation in their reticulo-rumens. This study is part of a larger program, characterising the rumen microbiomes of sheep which vary naturally in methane yield (g CH 4 /kg DM/day) and aims to define differences in microbial communities, and in gene and transcript abundances that can explain the animal methane phenotype. Rumen microbiome metagenomic and metatranscriptomic data were analysed by Gene Set Enrichment, sparse partial least squares regression and the Wilcoxon Rank Sum test to estimate correlations between specific KEGG bacterial pathways/genes and high methane yield in sheep. KEGG genes enriched in high methane yield sheep were reassembled from raw reads and existing contigs and analysed by MEGAN to predict their phylogenetic origin. Protein coding sequences from Succinivibrio dextrinosolvens strains were analysed using Effective DB to predict bacterial type III secreted proteins. The effect of S. dextrinosolvens strain H5 growth on methane formation by rumen methanogens was explored using co-cultures. Detailed analysis of the rumen microbiomes of high methane yield sheep shows that gene and transcript abundances of bacterial type III secretion system genes are positively correlated with methane yield in sheep. Most of the bacterial type III secretion system genes could not be assigned to a particular bacterial group, but several genes were affiliated with the genus Succinivibrio, and searches of bacterial genome sequences found that strains of S. dextrinosolvens were part of a small group of rumen bacteria that encode this type of secretion system. In co-culture experiments, S. dextrinosolvens strain H5 showed a growth-enhancing effect on a methanogen belonging to the order Methanomassiliicoccales, and inhibition of a representative of the Methanobrevibacter gottschalkii clade. This is the first report of bacterial type III secretion system genes being associated with high

A gene-targeted approach to investigate the intestinal butyrate-producing bacterial community

PubMed Central

2013-01-01

Background Butyrate, which is produced by the human microbiome, is essential for a well-functioning colon. Bacteria that produce butyrate are phylogenetically diverse, which hinders their accurate detection based on conventional phylogenetic markers. As a result, reliable information on this important bacterial group is often lacking in microbiome research. Results In this study we describe a gene-targeted approach for 454 pyrotag sequencing and quantitative polymerase chain reaction for the final genes in the two primary bacterial butyrate synthesis pathways, butyryl-CoA:acetate CoA-transferase (but) and butyrate kinase (buk). We monitored the establishment and early succession of butyrate-producing communities in four patients with ulcerative colitis who underwent a colectomy with ileal pouch anal anastomosis and compared it with three control samples from healthy colons. All patients established an abundant butyrate-producing community (approximately 5% to 26% of the total community) in the pouch within the 2-month study, but patterns were distinctive among individuals. Only one patient harbored a community profile similar to the healthy controls, in which there was a predominance of but genes that are similar to reference genes from Acidaminococcus sp., Eubacterium sp., Faecalibacterium prausnitzii and Roseburia sp., and an almost complete absence of buk genes. Two patients were greatly enriched in buk genes similar to those of Clostridium butyricum and C. perfringens, whereas a fourth patient displayed abundant communities containing both genes. Most butyrate producers identified in previous studies were detected and the general patterns of taxa found were supported by 16S rRNA gene pyrotag analysis, but the gene-targeted approach provided more detail about the potential butyrate-producing members of the community. Conclusions The presented approach provides quantitative and genotypic insights into butyrate-producing communities and facilitates a more specific

Proteome analysis of Arabidopsis seedlings exposed to bacterial volatiles.

PubMed

Kwon, Young Sang; Ryu, Choong-Min; Lee, Soohyun; Park, Hyo Bee; Han, Ki Soo; Lee, Jung Han; Lee, Kyunghee; Chung, Woo Sik; Jeong, Mi-Jeong; Kim, Hee Kyu; Bae, Dong-Won

2010-11-01

Plant root-associated bacteria (rhizobacteria) elicit plant basal immunity referred to as induced systemic resistance (ISR) against multiple pathogens. Among multi-bacterial determinants involving such ISR, the induction of ISR and promotion of growth by bacterial volatile compounds was previously reported. To exploit global de novo expression of plant proteins by bacterial volatiles, proteomic analysis was performed after exposure of Arabidopsis plants to the rhizobacterium Bacillus subtilis GB03. Ethylene biosynthesis enzymes were significantly up-regulated. Analysis by quantitative reverse transcriptase polymerase chain reaction confirmed that ethylene biosynthesis-related genes SAM-2, ACS4, ACS12, and ACO2 as well as ethylene response genes, ERF1, GST2, and CHIB were up-regulated by the exposure to bacterial volatiles. More interestingly, the emission of bacterial volatiles significantly up-regulated both key defense mechanisms mediated by jasmonic acid and salicylic acid signaling pathways. In addition, high accumulation of antioxidant proteins also provided evidence of decreased sensitivity to reactive oxygen species during the elicitation of ISR by bacterial volatiles. The present results suggest that the proteomic analysis of plant defense responses in bacterial volatile-mediated ISR can reveal the mechanisms of plant basal defenses orchestrated by endogenous ethylene production pathways and the generation of reactive oxygen species.

Trimeric autotransporter adhesins contribute to Actinobacillus pleuropneumoniae pathogenicity in mice and regulate bacterial gene expression during interactions between bacteria and porcine primary alveolar macrophages.

PubMed

Qin, Wanhai; Wang, Lei; Zhai, Ruidong; Ma, Qiuyue; Liu, Jianfang; Bao, Chuntong; Zhang, Hu; Sun, Changjiang; Feng, Xin; Gu, Jingmin; Du, Chongtao; Han, Wenyu; Langford, P R; Lei, Liancheng

2016-01-01

Actinobacillus pleuropneumoniae is an important pathogen that causes respiratory disease in pigs. Trimeric autotransporter adhesin (TAA) is a recently discovered bacterial virulence factor that mediates bacterial adhesion and colonization. Two TAA coding genes have been found in the genome of A. pleuropneumoniae strain 5b L20, but whether they contribute to bacterial pathogenicity is unclear. In this study, we used homologous recombination to construct a double-gene deletion mutant, ΔTAA, in which both TAA coding genes were deleted and used it in in vivo and in vitro studies to confirm that TAAs participate in bacterial auto-aggregation, biofilm formation, cell adhesion and virulence in mice. A microarray analysis was used to determine whether TAAs can regulate other A. pleuropneumoniae genes during interactions with porcine primary alveolar macrophages. The results showed that deletion of both TAA coding genes up-regulated 36 genes, including ene1514, hofB and tbpB2, and simultaneously down-regulated 36 genes, including lgt, murF and ftsY. These data illustrate that TAAs help to maintain full bacterial virulence both directly, through their bioactivity, and indirectly by regulating the bacterial type II and IV secretion systems and regulating the synthesis or secretion of virulence factors. This study not only enhances our understanding of the role of TAAs but also has significance for those studying A. pleuropneumoniae pathogenesis.

Lateral organ boundaries 1 is a disease susceptibility gene for citrus bacterial canker disease

PubMed Central

Hu, Yang; Zhang, Junli; Jia, Hongge; Sosso, Davide; Li, Ting; Frommer, Wolf B.; Yang, Bing; White, Frank F.; Wang, Nian; Jones, Jeffrey B.

2014-01-01

Citrus bacterial canker (CBC) disease occurs worldwide and incurs considerable costs both from control measures and yield losses. Bacteria that cause CBC require one of six known type III transcription activator-like (TAL) effector genes for the characteristic pustule formation at the site of infection. Here, we show that Xanthomonas citri subspecies citri strain Xcc306, with the type III TAL effector gene pthA4 or with the distinct yet biologically equivalent gene pthAw from strain XccAw, induces two host genes, CsLOB1 and CsSWEET1, in a TAL effector-dependent manner. CsLOB1 is a member of the Lateral Organ Boundaries (LOB) gene family of transcription factors, and CsSWEET1 is a homolog of the SWEET sugar transporter and rice disease susceptibility gene. Both TAL effectors drive expression of CsLOB1 and CsSWEET1 promoter reporter gene fusions when coexpressed in citrus or Nicotiana benthamiana. Artificially designed TAL effectors directed to sequences in the CsLOB1 promoter region, but not the CsSWEET1 promoter, promoted pustule formation and higher bacterial leaf populations. Three additional distinct TAL effector genes, pthA*, pthB, and pthC, also direct pustule formation and expression of CsLOB1. Unlike pthA4 and pthAw, pthB and pthC do not promote the expression of CsSWEET1. CsLOB1 expression was associated with the expression of genes associated with cell expansion. The results indicate that CBC-inciting species of Xanthomonas exploit a single host disease susceptibility gene by altering the expression of an otherwise developmentally regulated gene using any one of a diverse set of TAL effector genes in the pathogen populations. PMID:24474801

Lateral organ boundaries 1 is a disease susceptibility gene for citrus bacterial canker disease.

PubMed

Hu, Yang; Zhang, Junli; Jia, Hongge; Sosso, Davide; Li, Ting; Frommer, Wolf B; Yang, Bing; White, Frank F; Wang, Nian; Jones, Jeffrey B

2014-01-28

Citrus bacterial canker (CBC) disease occurs worldwide and incurs considerable costs both from control measures and yield losses. Bacteria that cause CBC require one of six known type III transcription activator-like (TAL) effector genes for the characteristic pustule formation at the site of infection. Here, we show that Xanthomonas citri subspecies citri strain Xcc306, with the type III TAL effector gene pthA4 or with the distinct yet biologically equivalent gene pthAw from strain XccA(w), induces two host genes, CsLOB1 and CsSWEET1, in a TAL effector-dependent manner. CsLOB1 is a member of the Lateral Organ Boundaries (LOB) gene family of transcription factors, and CsSWEET1 is a homolog of the SWEET sugar transporter and rice disease susceptibility gene. Both TAL effectors drive expression of CsLOB1 and CsSWEET1 promoter reporter gene fusions when coexpressed in citrus or Nicotiana benthamiana. Artificially designed TAL effectors directed to sequences in the CsLOB1 promoter region, but not the CsSWEET1 promoter, promoted pustule formation and higher bacterial leaf populations. Three additional distinct TAL effector genes, pthA*, pthB, and pthC, also direct pustule formation and expression of CsLOB1. Unlike pthA4 and pthAw, pthB and pthC do not promote the expression of CsSWEET1. CsLOB1 expression was associated with the expression of genes associated with cell expansion. The results indicate that CBC-inciting species of Xanthomonas exploit a single host disease susceptibility gene by altering the expression of an otherwise developmentally regulated gene using any one of a diverse set of TAL effector genes in the pathogen populations.

Whole genome sequencing options for bacterial strain typing and epidemiologic analysis based on single nucleotide polymorphism versus gene-by-gene-based approaches.

PubMed

Schürch, A C; Arredondo-Alonso, S; Willems, R J L; Goering, R V

2018-04-01

Whole genome sequence (WGS)-based strain typing finds increasing use in the epidemiologic analysis of bacterial pathogens in both public health as well as more localized infection control settings. This minireview describes methodologic approaches that have been explored for WGS-based epidemiologic analysis and considers the challenges and pitfalls of data interpretation. Personal collection of relevant publications. When applying WGS to study the molecular epidemiology of bacterial pathogens, genomic variability between strains is translated into measures of distance by determining single nucleotide polymorphisms in core genome alignments or by indexing allelic variation in hundreds to thousands of core genes, assigning types to unique allelic profiles. Interpreting isolate relatedness from these distances is highly organism specific, and attempts to establish species-specific cutoffs are unlikely to be generally applicable. In cases where single nucleotide polymorphism or core gene typing do not provide the resolution necessary for accurate assessment of the epidemiology of bacterial pathogens, inclusion of accessory gene or plasmid sequences may provide the additional required discrimination. As with all epidemiologic analysis, realizing the full potential of the revolutionary advances in WGS-based approaches requires understanding and dealing with issues related to the fundamental steps of data generation and interpretation. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

RAV transcription factors are essential for disease resistance against cassava bacterial blight via activation of melatonin biosynthesis genes.

PubMed

Wei, Yunxie; Chang, Yanli; Zeng, Hongqiu; Liu, Guoyin; He, Chaozu; Shi, Haitao

2018-01-01

With 1 AP2 domain and 1 B3 domain, 7 MeRAVs in apetala2/ethylene response factor (AP2/ERF) gene family have been identified in cassava. However, the in vivo roles of these remain unknown. Gene expression assays showed that the transcripts of MeRAVs were commonly regulated after Xanthomonas axonopodis pv manihotis (Xam) and MeRAVs were specifically located in plant cell nuclei. Through virus-induced gene silencing (VIGS) in cassava, we found that MeRAV1 and MeRAV2 are essential for plant disease resistance against cassava bacterial blight, as shown by the bacterial propagation of Xam in plant leaves. Through VIGS in cassava leaves and overexpression in cassava leave protoplasts, we found that MeRAV1 and MeRAV2 positively regulated melatonin biosynthesis genes and the endogenous melatonin level. Further investigation showed that MeRAV1 and MeRAV2 are direct transcriptional activators of 3 melatonin biosynthesis genes in cassava, as evidenced by chromatin immunoprecipitation-PCR in cassava leaf protoplasts and electrophoretic mobility shift assay. Moreover, cassava melatonin biosynthesis genes also positively regulated plant disease resistance. Taken together, this study identified MeRAV1 and MeRAV2 as common and upstream transcription factors of melatonin synthesis genes in cassava and revealed a model of MeRAV1 and MeRAV2-melatonin biosynthesis genes-melatonin level in plant disease resistance against cassava bacterial blight. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Feedback regulation of an Agrobacterium catalase gene katA involved in Agrobacterium-plant interaction.

PubMed

Xu, X Q; Li, L P; Pan, S Q

2001-11-01

Catalases are known to detoxify H2O2, a major component of oxidative stress imposed on a cell. An Agrobacterium tumefaciens catalase encoded by a chromosomal gene katA has been implicated as an important virulence factor as it is involved in detoxification of H2O2 released during Agrobacterium-plant interaction. In this paper, we report a feedback regulation pathway that controls the expression of katA in A. tumefaciens cells. We observed that katA could be induced by plant tissue sections and by acidic pH on a minimal medium, which resembles the plant environment that the bacteria encounter during the course of infection. This represents a new regulatory factor for catalase induction in bacteria. More importantly, a feedback regulation was observed when the katA-gfp expression was studied in different genetic backgrounds. We found that introduction of a wild-type katA gene encoding a functional catalase into A. tumefaciens cells could repress the katA-gfp expression over 60-fold. The katA gene could be induced by H2O2 and the encoded catalase could detoxify H2O2. In addition, the katA-gfp expression of one bacterial cell could be repressed by other surrounding catalase-proficient bacterial cells. Furthermore, mutation at katA caused a 10-fold increase of the intracellular H2O2 concentration in the bacteria grown on an acidic pH medium. These results suggest that the endogenous H2O2 generated during A. tumefaciens cell growth could serve as the intracellular and intercellular inducer for the katA gene expression and that the acidic pH could pose an oxidative stress on the bacteria. Surprisingly, one mutated KatA protein, exhibiting no significant catalase activity as a result of the alteration of two important residues at the putative active site, could partially repress the katA-gfp expression. The feedback regulation of the katA gene by both catalase activity and KatA protein could presumably maintain an appropriated level of catalase activity and H2O2 inside A

The dual oxidase gene BdDuox regulates the intestinal bacterial community homeostasis of Bactrocera dorsalis

PubMed Central

Yao, Zhichao; Wang, Ailin; Li, Yushan; Cai, Zhaohui; Lemaitre, Bruno; Zhang, Hongyu

2016-01-01

The guts of metazoans are in permanent contact with the microbial realm that includes beneficial symbionts, nonsymbionts, food-borne microbes and life-threatening pathogens. However, little is known concerning how host immunity affects gut bacterial community. Here, we analyze the role of a dual oxidase gene (BdDuox) in regulating the intestinal bacterial community homeostasis of the oriental fruit fly Bactrocera dorsalis. The results showed that knockdown of BdDuox led to an increased bacterial load, and to a decrease in the relative abundance of Enterobacteriaceae and Leuconostocaceae bacterial symbionts in the gut. The resulting dysbiosis, in turn, stimulates an immune response by activating BdDuox and promoting reactive oxygen species (ROS) production that regulates the composition and structure of the gut bacterial community to normal status by repressing the overgrowth of minor pathobionts. Our results suggest that BdDuox plays a pivotal role in regulating the homeostasis of the gut bacterial community in B. dorsalis. PMID:26565723

Bacterial plasmid-mediated quinolone resistance genes in aquatic environments in China

PubMed Central

Yan, Lei; Liu, Dan; Wang, Xin-Hua; Wang, Yunkun; Zhang, Bo; Wang, Mingyu; Xu, Hai

2017-01-01

Emerging antimicrobial resistance is a major threat to human’s health in the 21st century. Understanding and combating this issue requires a full and unbiased assessment of the current status on the prevalence of antimicrobial resistance genes and their correlation with each other and bacterial groups. In aquatic environments that are known reservoirs for antimicrobial resistance genes, we were able to reach this goal on plasmid-mediated quinolone resistance (PMQR) genes that lead to resistance to quinolones and possibly also to the co-emergence of resistance to β-lactams. Novel findings were made that qepA and aac-(6′)-Ib genes that were previously regarded as similarly abundant with qnr genes are now dominant among PMQR genes in aquatic environments. Further statistical analysis suggested that the correlation between PMQR and β-lactam resistance genes in the environment is still weak, that the correlations between antimicrobial resistance genes could be weakened by sufficient wastewater treatment, and that the prevalence of PMQR has been implicated in environmental, pathogenic, predatory, anaerobic, and more importantly, human symbiotic bacteria. This work provides a comprehensive analysis of PMQR genes in aquatic environments in Jinan, China, and provides information with which combat with the antimicrobial resistance problem may be fought. PMID:28094345

Phylogeny Inference of Closely Related Bacterial Genomes: Combining the Features of Both Overlapping Genes and Collinear Genomic Regions

PubMed Central

Zhang, Yan-Cong; Lin, Kui

2015-01-01

Overlapping genes (OGs) represent one type of widespread genomic feature in bacterial genomes and have been used as rare genomic markers in phylogeny inference of closely related bacterial species. However, the inference may experience a decrease in performance for phylogenomic analysis of too closely or too distantly related genomes. Another drawback of OGs as phylogenetic markers is that they usually take little account of the effects of genomic rearrangement on the similarity estimation, such as intra-chromosome/genome translocations, horizontal gene transfer, and gene losses. To explore such effects on the accuracy of phylogeny reconstruction, we combine phylogenetic signals of OGs with collinear genomic regions, here called locally collinear blocks (LCBs). By putting these together, we refine our previous metric of pairwise similarity between two closely related bacterial genomes. As a case study, we used this new method to reconstruct the phylogenies of 88 Enterobacteriale genomes of the class Gammaproteobacteria. Our results demonstrated that the topological accuracy of the inferred phylogeny was improved when both OGs and LCBs were simultaneously considered, suggesting that combining these two phylogenetic markers may reduce, to some extent, the influence of gene loss on phylogeny inference. Such phylogenomic studies, we believe, will help us to explore a more effective approach to increasing the robustness of phylogeny reconstruction of closely related bacterial organisms. PMID:26715828

Reduced toll-like receptor 4 and substance P gene expression is associated with airway bacterial colonization in children.

PubMed

Grissell, Terry V; Chang, Anne B; Gibson, Peter G

2007-04-01

Neuro-immune interactions are increasingly relevant to human health and disease. The neuropeptide Substance P also has antibacterial activity and bears similarities to the innate immune antibacterial defensins. This suggests possible co-regulation of neuropeptide and innate immune mediators. In this study, non-bronchoscopic bronchoalveolar lavage (BAL) was performed on 69 children. BAL was examined for cellular profile, microbiology (bacteria, virus) and gene expression for TLRs 2, 3, 4; chemokine receptors (CCR3, CCR5, CXCR1); neurotrophins and neurokinin genes (TAC1, TAC3, CGRP, NGF). In children with bacterial colonization (n=10) there was an airway inflammatory response with increased BAL neutrophils, IL-8 protein, and CXCR1 expression. Substance P (TAC1) and TLR4 RNA expression were reduced in children with bacterial colonization. TLR3 mRNA was increased in 7.2% (n=5) children with rhinovirus, and there was a non-significant trend to increased TLR2. There is evidence for co-regulation of neurokinin (TAC1) and TLR4 gene expression in airway cells from children with airway bacterial colonization and their reduced expression may be associated with an impaired bacterial clearance. (c) 2007 Wiley-Liss, Inc.

Relationship of the luminous bacterial symbiont of the Caribbean flashlight fish, Kryptophanaron alfredi (family Anomalopidae) to other luminous bacteria based on bacterial luciferase (luxA) genes.

PubMed

Haygood, M G

1990-01-01

Flashlight fishes (family Anomalopidae) have light organs that contain luminous bacterial symbionts. Although the symbionts have not yet been successfully cultured, the luciferase genes have been cloned directly from the light organ of the Caribbean species, Kryptophanaron alfredi. The goal of this project was to evaluate the relationship of the symbiont to free-living luminous bacteria by comparison of genes coding for bacterial luciferase (lux genes). Hybridization of a lux AB probe from the Kryptophanaron alfredi symbiont to DNAs from 9 strains (8 species) of luminous bacteria showed that none of the strains tested had lux genes highly similar to the symbiont. The most similar were a group consisting of Vibrio harveyi, Vibrio splendidus and Vibrio orientalis. The nucleotide sequence of the luciferase alpha subunit gene luxA) of the Kryptophanaron alfredi symbiont was determined in order to do a more detailed comparison with published luxA sequences from Vibrio harveyi, Vibrio fischeri and Photobacterium leiognathi. The hybridization results, sequence comparisons and the mol% G + C of the Kryptophanaron alfredi symbiont luxA gene suggest that the symbiont may be considered as a new species of luminous Vibrio related to Vibrio harveyi.

Genomic features of bacterial adaptation to plants

DOE PAGES

Levy, Asaf; Salas Gonzalez, Isai; Mittelviefhaus, Maximilian; ...

2017-12-18

Plants intimately associate with diverse bacteria. Plant-associated bacteria have ostensibly evolved genes that enable them to adapt to plant environments. However, the identities of such genes are mostly unknown, and their functions are poorly characterized. In this study, we sequenced 484 genomes of bacterial isolates from roots of Brassicaceae, poplar, and maize. We then compared 3,837 bacterial genomes to identify thousands of plant-associated gene clusters. Genomes of plant-associated bacteria encode more carbohydrate metabolism functions and fewer mobile elements than related non-plant-associated genomes do. We experimentally validated candidates from two sets of plant-associated genes: one involved in plant colonization, and themore » other serving in microbe–microbe competition between plant-associated bacteria. We also identified 64 plant-associated protein domains that potentially mimic plant domains; some are shared with plant-associated fungi and oomycetes. In conclusion, this work expands the genome-based understanding of plant–microbe interactions and provides potential leads for efficient and sustainable agriculture through microbiome engineering.« less

Genomic features of bacterial adaptation to plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levy, Asaf; Salas Gonzalez, Isai; Mittelviefhaus, Maximilian

Plants intimately associate with diverse bacteria. Plant-associated bacteria have ostensibly evolved genes that enable them to adapt to plant environments. However, the identities of such genes are mostly unknown, and their functions are poorly characterized. In this study, we sequenced 484 genomes of bacterial isolates from roots of Brassicaceae, poplar, and maize. We then compared 3,837 bacterial genomes to identify thousands of plant-associated gene clusters. Genomes of plant-associated bacteria encode more carbohydrate metabolism functions and fewer mobile elements than related non-plant-associated genomes do. We experimentally validated candidates from two sets of plant-associated genes: one involved in plant colonization, and themore » other serving in microbe–microbe competition between plant-associated bacteria. We also identified 64 plant-associated protein domains that potentially mimic plant domains; some are shared with plant-associated fungi and oomycetes. In conclusion, this work expands the genome-based understanding of plant–microbe interactions and provides potential leads for efficient and sustainable agriculture through microbiome engineering.« less

CONJUGAL GENE TRANSFER IN THE RHIZOSPHERE OF WATER GRASS (ECHINOCHLORA CRUSGALLI): INFLUENCE OF ROOT EXUDATE AND BACTERIAL ACTIVITY

EPA Science Inventory

The premise that genetic exchange is primarily localized in niches characterized by dense bacterial populations and high availability of growth substrates was tested by relating conjugal gene transfer of an RP4 derivative to availability of root exudates and bacterial metabolic a...

Identification of the bacterial etiology of culture-negative endocarditis by amplification and sequencing of a small ribosomal RNA gene.

PubMed

Khulordava, Irakli; Miller, Geraldine; Haas, David; Li, Haijing; McKinsey, Joel; Vanderende, Daniel; Tang, Yi-Wei

2003-05-01

We report two cases of culture-negative bacterial endocarditis in which the organisms were identified by amplification and sequencing of the bacterial 16S rRNA gene. These results support an important role for polymerase chain reaction followed by direct sequencing to determine the etiology of culture-negative bacterial endocarditis and to guide appropriate antimicrobial therapy.

Spatially Correlated Gene Expression in Bacterial Groups: The Role of Lineage History, Spatial Gradients, and Cell-Cell Interactions.

PubMed

van Vliet, Simon; Dal Co, Alma; Winkler, Annina R; Spriewald, Stefanie; Stecher, Bärbel; Ackermann, Martin

2018-04-25

Gene expression levels in clonal bacterial groups have been found to be spatially correlated. These correlations can partly be explained by the shared lineage history of nearby cells, although they could also arise from local cell-cell interactions. Here, we present a quantitative framework that allows us to disentangle the contributions of lineage history, long-range spatial gradients, and local cell-cell interactions to spatial correlations in gene expression. We study pathways involved in toxin production, SOS stress response, and metabolism in Escherichia coli microcolonies and find for all pathways that shared lineage history is the main cause of spatial correlations in gene expression levels. However, long-range spatial gradients and local cell-cell interactions also contributed to spatial correlations in SOS response, amino acid biosynthesis, and overall metabolic activity. Together, our data show that the phenotype of a cell is influenced by its lineage history and population context, raising the question of whether bacteria can arrange their activities in space to perform functions they cannot achieve alone. Copyright © 2018 Elsevier Inc. All rights reserved.

Identification of a cobia (Rachycentron canadum) CC chemokine gene and its involvement in the inflammatory response.

PubMed

Su, Youlu; Guo, Zhixun; Xu, Liwen; Jiang, Jingzhe; Wang, Jiangyong; Feng, Juan

2012-01-01

The chemokines regulate immune cell migration under inflammatory and physiological conditions. We investigated a CC chemokine gene (RcCC1) from cobia (Rachycentron canadum). The full-length RcCC1 cDNA is comprised 673 nucleotides and encodes a four-cysteine arrangement 99-amino-acid protein typical of known CC chemokines. The genomic DNA of RcCC1 consists of three exons and two introns. Phylogenetic analysis showed that RcCC1 was closest to the MIP group of CC chemokines. Quantitative real-time RT-PCR (qRT-PCR) analysis revealed RcCC1 was constitutively expressed in all tissues examined, with relative strong expression in gill, blood, kidney, spleen, and head kidney. The RcCC1 transcripts in the head kidney, spleen, and liver were quickly up-regulated after stimulation with formalin-inactivated Vibrio carchariae (bacterial vaccine) or polyriboinosinic polyribocytidylic acid (poly I:C). These results indicate RcCC1 not only plays a role in homeostasis, but also may be involved in inflammatory responses to bacterial and viral infection. Copyright © 2011 Elsevier Ltd. All rights reserved.

Fructose Degradation in the Haloarchaeon Haloferax volcanii Involves a Bacterial Type Phosphoenolpyruvate-Dependent Phosphotransferase System, Fructose-1-Phosphate Kinase, and Class II Fructose-1,6-Bisphosphate Aldolase

PubMed Central

Pickl, Andreas; Johnsen, Ulrike

2012-01-01

The halophilic archaeon Haloferax volcanii utilizes fructose as a sole carbon and energy source. Genes and enzymes involved in fructose uptake and degradation were identified by transcriptional analyses, deletion mutant experiments, and enzyme characterization. During growth on fructose, the gene cluster HVO_1495 to HVO_1499, encoding homologs of the five bacterial phosphotransferase system (PTS) components enzyme IIB (EIIB), enzyme I (EI), histidine protein (HPr), EIIA, and EIIC, was highly upregulated as a cotranscript. The in-frame deletion of HVO_1499, designated ptfC (ptf stands for phosphotransferase system for fructose) and encoding the putative fructose-specific membrane component EIIC, resulted in a loss of growth on fructose, which could be recovered by complementation in trans. Transcripts of HVO_1500 (pfkB) and HVO_1494 (fba), encoding putative fructose-1-phosphate kinase (1-PFK) and fructose-1,6-bisphosphate aldolase (FBA), respectively, as well as 1-PFK and FBA activities were specifically upregulated in fructose-grown cells. pfkB and fba knockout mutants did not grow on fructose, whereas growth on glucose was not inhibited, indicating the functional involvement of both enzymes in fructose catabolism. Recombinant 1-PFK and FBA obtained after homologous overexpression were characterized as having kinetic properties indicative of functional 1-PFK and a class II type FBA. From these data, we conclude that fructose uptake in H. volcanii involves a fructose-specific PTS generating fructose-1-phosphate, which is further converted via fructose-1,6-bisphosphate to triose phosphates by 1-PFK and FBA. This is the first report of the functional involvement of a bacterial-like PTS and of class II FBA in the sugar metabolism of archaea. PMID:22493022

Abundance of antibiotic resistance genes and bacterial community composition in wild freshwater fish species.

PubMed

Marti, Elisabet; Huerta, Belinda; Rodríguez-Mozaz, Sara; Barceló, Damià; Marcé, Rafael; Balcázar, Jose Luis

2018-04-01

This study was aimed to determine the abundance of four antibiotic resistance genes (bla TEM , ermB, qnrS and sulI), as well as bacterial community composition associated with the intestinal mucus of wild freshwater fish species collected from the Foix and La Llosa del Cavall reservoirs, which represent ecosystems with high and low anthropogenic disturbance, respectively. Water and sediments from these reservoirs were also collected and analyzed to determine the pollution level by antibiotics. The bla TEM gene was only detected in brown trout and Ebro barbel, which were collected from La Llosa del Cavall reservoir. In contrast, the sulI and qnrS genes were only detected in common carp, which were collected from the Foix reservoir. Although the ermB gene was also detected in common carp, the values were below the limit of quantification. Likewise, water and sediment samples from the Foix reservoir had higher concentrations and more classes of antibiotics than those from La Llosa del Cavall. Pyrosequencing analysis of 16S rRNA genes revealed significant differences in bacterial communities associated with the intestinal mucus of fish species. Therefore, these findings suggest that anthropogenic activities are not only increasing the pollution of aquatic environments, but also contributing to the emergence and spread of antibiotic resistance in organisms that inhabit such environments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Vertical Distribution of Bacterial Communities in the Indian Ocean as Revealed by Analyses of 16S rRNA and nasA Genes.

PubMed

Jiang, Xuexia; Jiao, Nianzhi

2016-09-01

Bacteria play an important role in the marine biogeochemical cycles. However, research on the bacterial community structure of the Indian Ocean is scarce, particularly within the vertical dimension. In this study, we investigated the bacterial diversity of the pelagic, mesopelagic and bathypelagic zones of the southwestern Indian Ocean (50.46°E, 37.71°S). The clone libraries constructed by 16S rRNA gene sequence revealed that most phylotypes retrieved from the Indian Ocean were highly divergent from those retrieved from other oceans. Vertical differences were observed based on the analysis of natural bacterial community populations derived from the 16S rRNA gene sequences. Based on the analysis of the nasA gene sequences from GenBank database, a pair of general primers was developed and used to amplify the bacterial nitrate-assimilating populations. Environmental factors play an important role in mediating the bacterial communities in the Indian Ocean revealed by canonical correlation analysis.

A bacterial view of the periodic table: genes and proteins for toxic inorganic ions.

PubMed

Silver, Simon; Phung, Le T

2005-12-01

Essentially all bacteria have genes for toxic metal ion resistances and these include those for Ag+, AsO2-, AsO4(3-), Cd2+ Co2+, CrO4(2-), Cu2+, Hg2+, Ni2+, Pb2+, TeO3(2-), Tl+ and Zn2+. The largest group of resistance systems functions by energy-dependent efflux of toxic ions. Fewer involve enzymatic transformations (oxidation, reduction, methylation, and demethylation) or metal-binding proteins (for example, metallothionein SmtA, chaperone CopZ and periplasmic silver binding protein SilE). Some of the efflux resistance systems are ATPases and others are chemiosmotic ion/proton exchangers. For example, Cd2+-efflux pumps of bacteria are either inner membrane P-type ATPases or three polypeptide RND chemiosmotic complexes consisting of an inner membrane pump, a periplasmic-bridging protein and an outer membrane channel. In addition to the best studied three-polypeptide chemiosmotic system, Czc (Cd2+, Zn2+, and Co2), others are known that efflux Ag+, Cu+, Ni2+, and Zn2+. Resistance to inorganic mercury, Hg2+ (and to organomercurials, such as CH3Hg+ and phenylmercury) involve a series of metal-binding and membrane transport proteins as well as the enzymes mercuric reductase and organomercurial lyase, which overall convert more toxic to less toxic forms. Arsenic resistance and metabolizing systems occur in three patterns, the widely-found ars operon that is present in most bacterial genomes and many plasmids, the more recently recognized arr genes for the periplasmic arsenate reductase that functions in anaerobic respiration as a terminal electron acceptor, and the aso genes for the periplasmic arsenite oxidase that functions as an initial electron donor in aerobic resistance to arsenite.

Identification of genes and gene clusters involved in mycotoxin synthesis

USDA-ARS?s Scientific Manuscript database

Research methods to identify and characterize genes involved in mycotoxin biosynthetic pathways have evolved considerably over the years. Before whole genome sequences were available (e.g. pre-genomics), work focused primarily on chemistry, biosynthetic mutant strains and molecular analysis of sing...

Conditions for the Evolution of Gene Clusters in Bacterial Genomes

PubMed Central

Ballouz, Sara; Francis, Andrew R.; Lan, Ruiting; Tanaka, Mark M.

2010-01-01

Genes encoding proteins in a common pathway are often found near each other along bacterial chromosomes. Several explanations have been proposed to account for the evolution of these structures. For instance, natural selection may directly favour gene clusters through a variety of mechanisms, such as increased efficiency of coregulation. An alternative and controversial hypothesis is the selfish operon model, which asserts that clustered arrangements of genes are more easily transferred to other species, thus improving the prospects for survival of the cluster. According to another hypothesis (the persistence model), genes that are in close proximity are less likely to be disrupted by deletions. Here we develop computational models to study the conditions under which gene clusters can evolve and persist. First, we examine the selfish operon model by re-implementing the simulation and running it under a wide range of conditions. Second, we introduce and study a Moran process in which there is natural selection for gene clustering and rearrangement occurs by genome inversion events. Finally, we develop and study a model that includes selection and inversion, which tracks the occurrence and fixation of rearrangements. Surprisingly, gene clusters fail to evolve under a wide range of conditions. Factors that promote the evolution of gene clusters include a low number of genes in the pathway, a high population size, and in the case of the selfish operon model, a high horizontal transfer rate. The computational analysis here has shown that the evolution of gene clusters can occur under both direct and indirect selection as long as certain conditions hold. Under these conditions the selfish operon model is still viable as an explanation for the evolution of gene clusters. PMID:20168992

Code-assisted discovery of TAL effector targets in bacterial leaf streak of rice reveals contrast with bacterial blight and a novel susceptibility gene

USDA-ARS?s Scientific Manuscript database

Transcription activator-like (TAL) effectors found in Xanthomonas spp. promote bacterial growth and plant susceptibility by binding specific DNA sequences or, effector-binding elements (EBEs), and inducing host gene expression. In this study, we have found substantially different transcriptional pro...

Involvement of NADH Oxidase in Biofilm Formation in Streptococcus sanguinis

PubMed Central

Ge, Xiuchun; Shi, Xiaoli; Shi, Limei; Liu, Jinlin; Stone, Victoria; Kong, Fanxiang; Kitten, Todd; Xu, Ping

2016-01-01

Biofilms play important roles in microbial communities and are related to infectious diseases. Here, we report direct evidence that a bacterial nox gene encoding NADH oxidase is involved in biofilm formation. A dramatic reduction in biofilm formation was observed in a Streptococcus sanguinis nox mutant under anaerobic conditions without any decrease in growth. The membrane fluidity of the mutant bacterial cells was found to be decreased and the fatty acid composition altered, with increased palmitic acid and decreased stearic acid and vaccenic acid. Extracellular DNA of the mutant was reduced in abundance and bacterial competence was suppressed. Gene expression analysis in the mutant identified two genes with altered expression, gtfP and Idh, which were found to be related to biofilm formation through examination of their deletion mutants. NADH oxidase-related metabolic pathways were analyzed, further clarifying the function of this enzyme in biofilm formation. PMID:26950587

{open_quotes}Horizontal{close_quotes} gene transfer from a transgenic potato line to a bacterial pathogen (Erwinia chrysanthemi) occurs - if at all - at an extremely low frequency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlueter, K.; Fuetterer, J.; Potrykus, I.

1995-10-01

The frequency of possible {open_quotes}horizontal{close_quotes} gene transfer between a plant and a tightly associated bacterial pathogen was studied in a model system consisting of transgenic Solanum tuberosum, containing a {beta}-lactamase gene linked to a pBR322 origin of replication, and Erwinia chrysanthemi. This experimental system offers optimal conditions for the detection of possible horizontal gene transfer events, even when they occur at very low frequency. Horizontal gene transfer was not detected under conditions mimicking a {open_quotes}natural{close_quotes} infection. The gradual, stepwise alteration of artificial, positive control conditions to idealized natural conditions, however, allowed the characterization of factors that affected gene transfer, andmore » revealed a gradual decrease of the gene transfer frequency from 6.3 x 10{sup -2} under optimal control conditions to a calculated 2.0 x 10{sub -17} under idealized natural conditions. These data, in combination with other published studies, argue that horizontal gene transfer is so rare as to be essentially irrelevant to any realistic assessment of the risk involved in release experiments involving transgenic plants. 22 refs., 3 figs., 2 tabs.« less

Transcriptomic analysis reveals tomato genes whose expression is induced specifically during effector-triggered immunity and identifies the Epk1 protein kinase which is required for the host response to three bacterial effector proteins.

PubMed

Pombo, Marina A; Zheng, Yi; Fernandez-Pozo, Noe; Dunham, Diane M; Fei, Zhangjun; Martin, Gregory B

2014-01-01

Plants have two related immune systems to defend themselves against pathogen attack. Initially,pattern-triggered immunity is activated upon recognition of microbe-associated molecular patterns by pattern recognition receptors. Pathogenic bacteria deliver effector proteins into the plant cell that interfere with this immune response and promote disease. However, some plants express resistance proteins that detect the presence of specific effectors leading to a robust defense response referred to as effector-triggered immunity. The interaction of tomato with Pseudomonas syringae pv. tomato is an established model system for understanding the molecular basis of these plant immune responses. We apply high-throughput RNA sequencing to this pathosystem to identify genes whose expression changes specifically during pattern-triggered or effector-triggered immunity. We then develop reporter genes for each of these responses that will enable characterization of the host response to the large collection of P. s. pv. tomato strains that express different combinations of effectors. Virus-induced gene silencing of 30 of the effector-triggered immunity-specific genes identifies Epk1 which encodes a predicted protein kinase from a family previously unknown to be involved in immunity. Knocked-down expression of Epk1 compromises effector-triggered immunity triggered by three bacterial effectors but not by effectors from non-bacterial pathogens. Epistasis experiments indicate that Epk1 acts upstream of effector-triggered immunity-associated MAP kinase signaling. Using RNA-seq technology we identify genes involved in specific immune responses. A functional genomics screen led to the discovery of Epk1, a novel predicted protein kinase required for plant defense activation upon recognition of three different bacterial effectors.

TaCPK2-A, a calcium-dependent protein kinase gene that is required for wheat powdery mildew resistance enhances bacterial blight resistance in transgenic rice.

PubMed

Geng, Shuaifeng; Li, Aili; Tang, Lichuan; Yin, Lingjie; Wu, Liang; Lei, Cailin; Guo, Xiuping; Zhang, Xin; Jiang, Guanghuai; Zhai, Wenxue; Wei, Yuming; Zheng, Youliang; Lan, Xiujin; Mao, Long

2013-08-01

Calcium-dependent protein kinases (CPKs) are important Ca2+ signalling components involved in complex immune and stress signalling networks; but the knowledge of CPK gene functions in the hexaploid wheat is limited. Previously, TaCPK2 was shown to be inducible by powdery mildew (Blumeria graminis tritici, Bgt) infection in wheat. Here, its functions in disease resistance are characterized further. This study shows the presence of defence-response and cold-response cis-elements on the promoters of the A subgenome homoeologue (TaCPK2-A) and D subgenome homoeologue (TaCPK2-D), respectively. Their expression patterns were then confirmed by quantitative real-time PCR (qRT-PCR) using genome-specific primers, where TaCPK2-A was induced by Bgt treatment while TaCPK2-D mainly responded to cold treatment. Downregulation of TaCPK2-A by virus-induced gene silencing (VIGS) causes loss of resistance to Bgt in resistant wheat lines, indicating that TaCPK2-A is required for powdery mildew resistance. Furthermore, overexpression of TaCPK2-A in rice enhanced bacterial blight (Xanthomonas oryzae pv. oryzae, Xoo) resistance. qRT-PCR analysis showed that overexpression of TaCPK2-A in rice promoted the expression of OsWRKY45-1, a transcription factor involved in both fungal and bacterial resistance by regulating jasmonic acid and salicylic acid signalling genes. The opposite effect was found in wheat TaCPK2-A VIGS plants, where the homologue of OsWRKY45-1 was significantly repressed. These data suggest that modulation of WRKY45-1 and associated defence-response genes by CPK2 genes may be the common mechanism for multiple disease resistance in grass species, which may have undergone subfunctionalization in promoters before the formation of hexaploid wheat.

TaCPK2-A, a calcium-dependent protein kinase gene that is required for wheat powdery mildew resistance enhances bacterial blight resistance in transgenic rice

PubMed Central

Geng, Shuaifeng; Li, Aili; Tang, Lichuan; Lan, Xiujin; Mao, Long

2013-01-01

Calcium-dependent protein kinases (CPKs) are important Ca2+ signalling components involved in complex immune and stress signalling networks; but the knowledge of CPK gene functions in the hexaploid wheat is limited. Previously, TaCPK2 was shown to be inducible by powdery mildew (Blumeria graminis tritici, Bgt) infection in wheat. Here, its functions in disease resistance are characterized further. This study shows the presence of defence-response and cold-response cis-elements on the promoters of the A subgenome homoeologue (TaCPK2-A) and D subgenome homoeologue (TaCPK2-D), respectively. Their expression patterns were then confirmed by quantitative real-time PCR (qRT-PCR) using genome-specific primers, where TaCPK2-A was induced by Bgt treatment while TaCPK2-D mainly responded to cold treatment. Downregulation of TaCPK2-A by virus-induced gene silencing (VIGS) causes loss of resistance to Bgt in resistant wheat lines, indicating that TaCPK2-A is required for powdery mildew resistance. Furthermore, overexpression of TaCPK2-A in rice enhanced bacterial blight (Xanthomonas oryzae pv. oryzae, Xoo) resistance. qRT-PCR analysis showed that overexpression of TaCPK2-A in rice promoted the expression of OsWRKY45-1, a transcription factor involved in both fungal and bacterial resistance by regulating jasmonic acid and salicylic acid signalling genes. The opposite effect was found in wheat TaCPK2-A VIGS plants, where the homologue of OsWRKY45-1 was significantly repressed. These data suggest that modulation of WRKY45-1 and associated defence-response genes by CPK2 genes may be the common mechanism for multiple disease resistance in grass species, which may have undergone subfunctionalization in promoters before the formation of hexaploid wheat. PMID:23918959

Phylotype Dynamics of Bacterial P Utilization Genes in Microbialites and Bacterioplankton of a Monomictic Endorheic Lake.

PubMed

Valdespino-Castillo, Patricia M; Alcántara-Hernández, Rocío J; Merino-Ibarra, Martín; Alcocer, Javier; Macek, Miroslav; Moreno-Guillén, Octavio A; Falcón, Luisa I

2017-02-01

Microbes can modulate ecosystem function since they harbor a vast genetic potential for biogeochemical cycling. The spatial and temporal dynamics of this genetic diversity should be acknowledged to establish a link between ecosystem function and community structure. In this study, we analyzed the genetic diversity of bacterial phosphorus utilization genes in two microbial assemblages, microbialites and bacterioplankton of Lake Alchichica, a semiclosed (i.e., endorheic) system with marked seasonality that varies in nutrient conditions, temperature, dissolved oxygen, and water column stability. We focused on dissolved organic phosphorus (DOP) utilization gene dynamics during contrasting mixing and stratification periods. Bacterial alkaline phosphatases (phoX and phoD) and alkaline beta-propeller phytases (bpp) were surveyed. DOP utilization genes showed different dynamics evidenced by a marked change within an intra-annual period and a differential circadian pattern of expression. Although Lake Alchichica is a semiclosed system, this dynamic turnover of phylotypes (from lake circulation to stratification) points to a different potential of DOP utilization by the microbial communities within periods. DOP utilization gene dynamics was different among genetic markers and among assemblages (microbialite vs. bacterioplankton). As estimated by the system's P mass balance, P inputs and outputs were similar in magnitude (difference was <10 %). A theoretical estimation of water column P monoesters was used to calculate the potential P fraction that can be remineralized on an annual basis. Overall, bacterial groups including Proteobacteria (Alpha and Gamma) and Bacteroidetes seem to be key participants in DOP utilization responses.

Genes involved in convergent evolution of eusociality in bees

PubMed Central

Woodard, S. Hollis; Fischman, Brielle J.; Venkat, Aarti; Hudson, Matt E.; Varala, Kranthi; Cameron, Sydney A.; Clark, Andrew G.; Robinson, Gene E.

2011-01-01

Eusociality has arisen independently at least 11 times in insects. Despite this convergence, there are striking differences among eusocial lifestyles, ranging from species living in small colonies with overt conflict over reproduction to species in which colonies contain hundreds of thousands of highly specialized sterile workers produced by one or a few queens. Although the evolution of eusociality has been intensively studied, the genetic changes involved in the evolution of eusociality are relatively unknown. We examined patterns of molecular evolution across three independent origins of eusociality by sequencing transcriptomes of nine socially diverse bee species and combining these data with genome sequence from the honey bee Apis mellifera to generate orthologous sequence alignments for 3,647 genes. We found a shared set of 212 genes with a molecular signature of accelerated evolution across all eusocial lineages studied, as well as unique sets of 173 and 218 genes with a signature of accelerated evolution specific to either highly or primitively eusocial lineages, respectively. These results demonstrate that convergent evolution can involve a mosaic pattern of molecular changes in both shared and lineage-specific sets of genes. Genes involved in signal transduction, gland development, and carbohydrate metabolism are among the most prominent rapidly evolving genes in eusocial lineages. These findings provide a starting point for linking specific genetic changes to the evolution of eusociality. PMID:21482769

Protein expression of preferred human codon-optimized Gaussia luciferase genes with an artificial open-reading frame in mammalian and bacterial cells.

PubMed

Inouye, Satoshi; Suzuki, Takahiro

2016-12-01

The protein expressions of three preferred human codon-optimized Gaussia luciferase genes (pGLuc, EpGLuc, and KpGLuc) were characterized in mammalian and bacterial cells by comparing them with those of wild-type Gaussia luciferase gene (wGLuc) and human codon-optimized Gaussia luciferase gene (hGLuc). Two synthetic genes of EpGLuc and KpGLuc containing the complete preferred human codons have an artificial open-reading frame; however, they had the similar protein expression levels to those of pGLuc and hGLuc in mammalian cells. In bacterial cells, the protein expressions of pGLuc, EpGLuc, and KpGLuc with approximately 65% GC content were the same and showed approximately 60% activities of wGLuc and hGLuc. The artificial open-reading frame in EpGLuc and KpGLuc did not affect the protein expression in mammalian and bacterial cells. Copyright © 2016 Elsevier Inc. All rights reserved.

Diversity of bacterial dimethylsulfoniopropionate degradation genes in surface seawater of Arctic Kongsfjorden.

PubMed

Zeng, Yin-Xin; Qiao, Zong-Yun; Yu, Yong; Li, Hui-Rong; Luo, Wei

2016-09-08

Dimethylsulfoniopropionate (DMSP), which is the major source of organic sulfur in the world's oceans, plays a significant role in the global sulfur cycle. This compound is rapidly degraded by marine bacteria either by cleavage to dimethylsulfide (DMS) or demethylation to 3-methylmercaptopropionate (MMPA). The diversity of genes encoding bacterial demethylation (dmdA) and DMS production (dddL and dddP) were measured in Arctic Kongsfjorden. Both dmdA and dddL genes were detected in all stations along a transect from the outer to the inner fjord, while dddP gene was only found in the outer and middle parts of the fjord. The dmdA gene was completely confined to the Roseobacter clade, while the dddL gene was confined to the genus Sulfitobacter. Although the dddP gene pool was also dominated by homologs from the Roseobacter clade, there were a few dddP genes showing close relationships to both Alphaproteobacter and Gammaproteobacter. The results of this study suggest that the Roseobacter clade may play an important role in DMSP catabolism via both demethylation and cleavage pathways in surface waters of Kongsfjorden during summer.

Diversity of bacterial dimethylsulfoniopropionate degradation genes in surface seawater of Arctic Kongsfjorden

NASA Astrophysics Data System (ADS)

Zeng, Yin-Xin; Qiao, Zong-Yun; Yu, Yong; Li, Hui-Rong; Luo, Wei

2016-09-01

Dimethylsulfoniopropionate (DMSP), which is the major source of organic sulfur in the world’s oceans, plays a significant role in the global sulfur cycle. This compound is rapidly degraded by marine bacteria either by cleavage to dimethylsulfide (DMS) or demethylation to 3-methylmercaptopropionate (MMPA). The diversity of genes encoding bacterial demethylation (dmdA) and DMS production (dddL and dddP) were measured in Arctic Kongsfjorden. Both dmdA and dddL genes were detected in all stations along a transect from the outer to the inner fjord, while dddP gene was only found in the outer and middle parts of the fjord. The dmdA gene was completely confined to the Roseobacter clade, while the dddL gene was confined to the genus Sulfitobacter. Although the dddP gene pool was also dominated by homologs from the Roseobacter clade, there were a few dddP genes showing close relationships to both Alphaproteobacter and Gammaproteobacter. The results of this study suggest that the Roseobacter clade may play an important role in DMSP catabolism via both demethylation and cleavage pathways in surface waters of Kongsfjorden during summer.

Analysis of gene expression levels in individual bacterial cells without image segmentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwak, In Hae; Son, Minjun; Hagen, Stephen J., E-mail: sjhagen@ufl.edu

2012-05-11

Highlights: Black-Right-Pointing-Pointer We present a method for extracting gene expression data from images of bacterial cells. Black-Right-Pointing-Pointer The method does not employ cell segmentation and does not require high magnification. Black-Right-Pointing-Pointer Fluorescence and phase contrast images of the cells are correlated through the physics of phase contrast. Black-Right-Pointing-Pointer We demonstrate the method by characterizing noisy expression of comX in Streptococcus mutans. -- Abstract: Studies of stochasticity in gene expression typically make use of fluorescent protein reporters, which permit the measurement of expression levels within individual cells by fluorescence microscopy. Analysis of such microscopy images is almost invariably based on amore » segmentation algorithm, where the image of a cell or cluster is analyzed mathematically to delineate individual cell boundaries. However segmentation can be ineffective for studying bacterial cells or clusters, especially at lower magnification, where outlines of individual cells are poorly resolved. Here we demonstrate an alternative method for analyzing such images without segmentation. The method employs a comparison between the pixel brightness in phase contrast vs fluorescence microscopy images. By fitting the correlation between phase contrast and fluorescence intensity to a physical model, we obtain well-defined estimates for the different levels of gene expression that are present in the cell or cluster. The method reveals the boundaries of the individual cells, even if the source images lack the resolution to show these boundaries clearly.« less

Variation of bacterial communities and expression of Toll-like receptor genes in the rumen of steers differing in susceptibility to subacute ruminal acidosis.

PubMed

Chen, Yanhong; Oba, Masahito; Guan, Le Luo

2012-10-12

In order to determine differences in the ruminal bacterial community and host Toll-like receptor (TLR) gene expression of beef cattle with different susceptibility to acidosis, rumen papillae and content were collected from acidosis-susceptible (AS, n=3) and acidosis-resistant (AR, n=3) steers. The ruminal bacterial community was characterized using PCR-denaturing gradient gel electrophoresis (PCR-DGGE) and quantitative real time PCR (qRT-PCR) analysis. Global R analysis of bacterial profile similarity revealed that bacterial diversity was significantly different between AR and AS groups for both rumen content (P=0.001) and epithelial (P=0.002) communities. The copy number of total bacterial 16S rRNA genes in content of AS steers was 10-fold higher than that of AR steers, and the copy number of total 16S rRNA genes of epimural bacteria in AR steers was positively correlated with ruminal pH (r=0.59, P=0.04), and negatively correlated with total VFA concentration (r=-0.59, P=0.05). The expressions of host TLR2 and 4 genes were significantly higher in AR steers compared to those in AS steers. These findings enhance our understanding about the ruminal microbial ecology and host gene expression changes that may be useful in the prevention of ruminal acidosis. Copyright © 2012 Elsevier B.V. All rights reserved.

Active bacterial community structure along vertical redox gradients in Baltic Sea sediment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jansson, Janet; Edlund, Anna; Hardeman, Fredrik

Community structures of active bacterial populations were investigated along a vertical redox profile in coastal Baltic Sea sediments by terminal-restriction fragment length polymorphism (T-RFLP) and clone library analysis. According to correspondence analysis of T-RFLP results and sequencing of cloned 16S rRNA genes, the microbial community structures at three redox depths (179 mV, -64 mV and -337 mV) differed significantly. The bacterial communities in the community DNA differed from those in bromodeoxyuridine (BrdU)-labeled DNA, indicating that the growing members of the community that incorporated BrdU were not necessarily the most dominant members. The structures of the actively growing bacterial communities weremore » most strongly correlated to organic carbon followed by total nitrogen and redox potentials. Bacterial identification by sequencing of 16S rRNA genes from clones of BrdU-labeled DNA and DNA from reverse transcription PCR (rt-PCR) showed that bacterial taxa involved in nitrogen and sulfur cycling were metabolically active along the redox profiles. Several sequences had low similarities to previously detected sequences indicating that novel lineages of bacteria are present in Baltic Sea sediments. Also, a high number of different 16S rRNA gene sequences representing different phyla were detected at all sampling depths.« less

Bacterial DNA detected on pathologically changed heart valves using 16S rRNA gene amplification.

PubMed

Chalupova, Miroslava; Skalova, Anna; Hajek, Tomas; Geigerova, Lenka; Kralova, Dana; Liska, Pavel; Hecova, Hana; Molacek, Jiri; Hrabak, Jaroslav

2018-05-22

Nowadays, dental diseases are one of the most common illnesses in the world. Some of them can lead to translocation of oral bacteria to the bloodstream causing intermittent bacteraemia. Therefore, a potential association between oral infection and cardiovascular diseases has been discussed in recent years as a result of adhesion of oral microbes to the heart valves. The aim of this study was to detect oral bacteria on pathologically changed heart valves not caused by infective endocarditis. In the study, patients with pathologically changed heart valves were involved. Samples of heart valves removed during heart valve replacement surgery were cut into two parts. One aliquot was cultivated aerobically and anaerobically. Bacterial DNA was extracted using Ultra-Deep Microbiome Prep (Molzym GmbH, Bremen, Germany) followed by a 16S rRNA gene PCR amplification using Mastermix 16S Complete kit (Molzym GmbH, Bremen, Germany). Positive PCR products were sequenced and the sequences were analyzed using BLAST database ( http://www.ncbi.nlm.nih/BLAST ). During the study period, 41 samples were processed. Bacterial DNA of the following bacteria was detected in 21 samples: Cutibacterium acnes (formerly Propionibacterium acnes) (n = 11; 52.38% of patients with positive bacterial DNA detection), Staphylococcus sp. (n = 9; 42.86%), Streptococcus sp. (n = 1; 4.76%), Streptococcus sanguinis (n = 4; 19.05%), Streptococcus oralis (n = 1; 4.76%), Carnobacterium sp. (n = 1; 4.76%), Bacillus sp. (n = 2; 9.52%), and Bergeyella sp. (n = 1; 4.76%). In nine samples, multiple bacteria were found. Our results showed significant appearance of bacteria on pathologically changed heart valves in patients with no symptoms of infective endocarditis.

Using DGGE and 16S rRNA gene sequence analysis to evaluate changes in oral bacterial composition.

PubMed

Chen, Zhou; Trivedi, Harsh M; Chhun, Nok; Barnes, Virginia M; Saxena, Deepak; Xu, Tao; Li, Yihong

2011-01-01

To investigate whether a standard dental prophylaxis followed by tooth brushing with an antibacterial dentifrice will affect the oral bacterial community, as determined by denaturing gradient gel electrophoresis (DGGE) combined with 16S rRNA gene sequence analysis. Twenty-four healthy adults were instructed to brush their teeth using commercial dentifrice for 1 week during a washout period. An initial set of pooled supragingival plaque samples was collected from each participant at baseline (0 h) before prophylaxis treatment. The subjects were given a clinical examination and dental prophylaxis and asked to brush for 1 min with a dentifrice containing 0.3% triclosan, 2.0% PVM/MA copolymer and 0.243% sodium fluoride (Colgate Total). On the following day, a second set of pooled supragingival plaque samples (24 h) was collected. Total bacterial genomic DNA was isolated from the samples. Differences in the microbial composition before and after the prophylactic procedure and tooth brushing were assessed by comparing the DGGE profiles and 16S rRNA gene segments sequence analysis. Two distinct clusters of DGGE profiles were found, suggesting that a shift in the microbial composition had occurred 24 h after the prophylaxis and brushing. A detailed sequencing analysis of 16S rRNA gene segments further identified 6 phyla and 29 genera, including known and unknown bacterial species. Importantly, an increase in bacterial diversity was observed after 24 h, including members of the Streptococcaceae family, Prevotella, Corynebacterium, TM7 and other commensal bacteria. The results suggest that the use of a standard prophylaxis followed by the use of the dentifrice containing 0.3% triclosan, 2.0% PVM/MA copolymer and 0.243% sodium fluoride may promote a healthier composition within the oral bacterial community.

Genes involved in Beauveria bassiana infection to Galleria mellonella.

PubMed

Chen, Anhui; Wang, Yulong; Shao, Ying; Zhou, Qiumei; Chen, Shanglong; Wu, Yonghua; Chen, Hongwei; Liu, Enqi

2018-05-01

The ascomycete fungus Beauveria bassiana is a natural pathogen of hundreds of insect species and is commercially produced as an environmentally friendly mycoinsecticide. Many genes involved in fungal insecticide infection have been identified but few have been further explored. In this study, we constructed three transcriptomes of B. bassiana at 24, 48 and 72 h post infection of insect pests (BbI) or control (BbC). There were 3148, 3613 and 4922 genes differentially expressed at 24, 48 and 72 h post BbI/BbC infection, respectively. A large number of genes and pathways involved in infection were identified. To further analyze those genes, expression patterns across different infection stages (0, 12, 24, 36, 48, 60, 72 and 84 h) were studied using quantitative RT-PCR. This analysis showed that the infection-related genes could be divided into four patterns: highly expressed throughout the whole infection process (thioredoxin 1); highly expressed during early stages of infection but lowly expressed after the insect death (adhesin protein Mad1); lowly expressed during early infection but highly expressed after insect death (cation transporter, OpS13); or lowly expressed across the entire infection process (catalase protein). The data provide novel insights into the insect-pathogen interaction and help to uncover the molecular mechanisms involved in fungal infection of insect pests.

Exploring the Abundance and Diversity of Bacterial Communities and Quantifying Antibiotic-Related Genes Along an Elevational Gradient in Taibai Mountain, China.

PubMed

Peng, Chu; Wang, He; Jiang, Yingying; Yang, Jinhua; Lai, Hangxian; Wei, Xiaomin

2018-05-10

Thus far, no studies have investigated the soil microbial diversity over an elevational gradient in Taibai Mountain, the central massif of the Qinling Mountain Range. Here, we used Illumina sequencing and quantitative PCR of the 16S rRNA gene to assess the diversity and abundance of bacterial communities along an elevational gradient in representative vegetation soils in Taibai Mountain. We identified the soil, climate, and vegetation factors driving the variations in soil bacterial community structure by Pearson correlation and redundancy analysis. We also evaluated the potential for antibiotic discovery by quantitative PCR of the PKS-I, PKS-II, and NRPS genes from Actinobacteria. The results showed that soil bacterial alpha diversity increased first and then decreased with an elevational rise in both the northern and southern slopes of Taibai Mountain. The bacterial abundance was significantly correlated with soil organic matter and nitrate nitrogen. The average relative abundance of Actinobacteria in Taibai Mountain was markedly higher than those in other mountain forest soils. The absolute abundance of PKS and NPRS gene was significantly higher in the tested soils compared with the gene copy numbers reported in tropical urban soils. Taibai Mountain is rich in actinomycete resources and has great potential for antibiotic excavation.

A Homolog of Bacillus subtilis Trigger Factor in Listeria monocytogenes Is Involved in Stress Tolerance and Bacterial Virulence

PubMed Central

Bigot, Armelle; Botton, Eleonore; Dubail, Iharilalao; Charbit, Alain

2006-01-01

Molecular chaperones play an essential role in the folding of nascent chain polypeptides, as well as in the refolding and degradation of misfolded or aggregated proteins. They also assist in protein translocation and participate in stress functions. We identified a gene, designated tig, encoding a protein homologous to trigger factor (TF), a cytosolic ribosome-associated chaperone, in the genome of Listeria monocytogenes. We constructed a chromosomal Δtig deletion and evaluated the impact of the mutation on bacterial growth in broth under various stress conditions and on pathogenesis. The Δtig deletion did not affect cell viability but impaired survival in the presence of heat and ethanol stresses. We also identified the ffh gene, encoding a protein homologous to the SRP54 eukaryotic component of the signal recognition particle. However, a Δffh deletion was not tolerated, suggesting that Ffh is essential, as it is in Bacillus subtilis and Escherichia coli. Thus, although dispensable for growth, TF is involved in the stress response of L. monocytogenes. The Δtig mutant showed no or very modest intracellular survival defects in eukaryotic cells. However, in vivo it showed a reduced capacity to persist in the spleens and livers of infected mice, revealing that TF has a role in the pathogenicity of L. monocytogenes. PMID:17021213

The role of a groundwater bacterial community in the degradation of the herbicide terbuthylazine.

PubMed

Caracciolo, Anna Barra; Fajardo, Carmen; Grenni, Paola; Saccà, Maria Ludovica; Amalfitano, Stefano; Ciccoli, Roberto; Martin, Margarita; Gibello, Alicia

2010-01-01

A bacterial community in an aquifer contaminated by s-triazines was studied. Groundwater microcosms were treated with terbuthylazine at a concentration of 100 microg L(-1) and degradation of the herbicide was assessed. The bacterial community structure (abundance and phylogenetic composition) and function (carbon production and cell viability) were analysed. The bacterial community was able to degrade the terbuthylazine; in particular, Betaproteobacteria were involved in the herbicide biotransformation. Identification of some bacterial isolates by PCR amplification of the 16S rRNA gene revealed the presence of two Betaproteobacteria species able to degrade the herbicide: Advenella incenata and Janthinobacterium lividum. PCR detection of the genes encoding s-triazine-degrading enzymes indicated the presence of the atzA and atzB genes in A. incenata and the atzB and atzC genes in J. lividum. The nucleotide sequences of the PCR fragments of the atz genes from these strains were 100% identical to the homologous genes of the Pseudomonas sp. strain ADP. In conclusion, the results show the potential for the use of a natural attenuation strategy in the treatment of aquifers polluted with the terbuthylazine. The two bacteria isolated could facilitate the implementation of effective bioremediation protocols, especially in the case of the significant amounts of herbicide that can be found in groundwater as a result of accidental spills.

The intrinsic resistome of bacterial pathogens

PubMed Central

Olivares, Jorge; Bernardini, Alejandra; Garcia-Leon, Guillermo; Corona, Fernando; B. Sanchez, Maria; Martinez, Jose L.

2013-01-01

Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyze recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice. PMID:23641241

The intrinsic resistome of bacterial pathogens.

PubMed

Olivares, Jorge; Bernardini, Alejandra; Garcia-Leon, Guillermo; Corona, Fernando; B Sanchez, Maria; Martinez, Jose L

2013-01-01

Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyze recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice.

Multiple Neuropeptide-Coding Genes Involved in Planarian Pharynx Extension.

PubMed

Shimoyama, Seira; Inoue, Takeshi; Kashima, Makoto; Agata, Kiyokazu

2016-06-01

Planarian feeding behavior involves three steps: moving toward food, extending the pharynx from their planarian's ventral side after arriving at the food, and ingesting the food through the pharynx. Although pharynx extension is a remarkable behavior, it remains unknown what neuronal cell types are involved in its regulation. To identify neurons involved in regulating pharynx extension, we quantitatively analyzed pharynx extension and sought to identify these neurons by RNA interference (RNAi) and in situ hybridization. This assay, when performed using planarians with amputation of various body parts, clearly showed that the head portion is indispensable for inducing pharynx extension. We thus tested the effects of knockdown of brain neurons such as serotonergic, GABAergic, and dopaminergic neurons by RNAi, but did not observe any effects on pharynx extension behavior. However, animals with RNAi of the Prohormone Convertase 2 (PC2, a neuropeptide processing enzyme) gene did not perform the pharynx extension behavior, suggesting the possible involvement of neuropeptide(s in the regulation of pharynx extension. We screened 24 neuropeptide-coding genes, analyzed their functions by RNAi using the pharynx extension assay system, and identified at least five neuropeptide genes involved in pharynx extension. These was expressed in different cells or neurons, and some of them were expressed in the brain, suggesting complex regulation of planarian feeding behavior by the nervous system.

Prevalence of antibiotic resistance genes in bacterial communities associated with Cladophora glomerata mats along the nearshore of Lake Ontario.

PubMed

Ibsen, Michael; Fernando, Dinesh M; Kumar, Ayush; Kirkwood, Andrea E

2017-05-01

The alga Cladophora glomerata can erupt in nuisance blooms throughout the lower Great Lakes. Since bacterial abundance increases with the emergence and decay of Cladophora, we investigated the prevalence of antibiotic resistance (ABR) in Cladophora-associated bacterial communities up-gradient and down-gradient from a large sewage treatment plant (STP) on Lake Ontario. Although STPs are well-known sources of ABR, we also expected detectable ABR from up-gradient wetland communities, since they receive surface run-off from urban and agricultural sources. Statistically significant differences in aquatic bacterial abundance and ABR were found between down-gradient beach samples and up-gradient coastal wetland samples (ANOVA, Holm-Sidak test, p < 0.05). Decaying and free-floating Cladophora sampled near the STP had the highest bacterial densities overall, including on ampicillin- and vancomycin-treated plates. However, quantitative polymerase chain reaction analysis of the ABR genes ampC, tetA, tetB, and vanA from environmental communities showed a different pattern. Some of the highest ABR gene levels occurred at the 2 coastal wetland sites (vanA). Overall, bacterial ABR profiles from environmental samples were distinguishable between living and decaying Cladophora, inferring that Cladophora may control bacterial ABR depending on its life-cycle stage. Our results also show how spatially and temporally dynamic ABR is in nearshore aquatic bacteria, which warrants further research.

Amplification and sequence analysis of partial bacterial 16S ribosomal RNA gene in gallbladder bile from patients with primary biliary cirrhosis.

PubMed

Hiramatsu, K; Harada, K; Tsuneyama, K; Sasaki, M; Fujita, S; Hashimoto, T; Kaneko, S; Kobayashi, K; Nakanuma, Y

2000-07-01

The etiopathogenesis of bile duct lesion in primary biliary cirrhosis is unknown, though the participation of bacteria and/or their components and products is suspected. In this study, we tried to detect and identify bacteria in the bile of patients with primary biliary cirrhosis by polymerase chain reaction using universal bacterial primers of the 16S ribosomal RNA gene. Gallbladder bile samples from 15 patients with primary biliary cirrhosis, 5 with primary sclerosing cholangitis, 5 with hepatitis C virus-related liver cirrhosis, 11 with cholecystolithiasis, and from 12 normal adult gallbladders were used. In addition to the culture study, partial bacterial 16S ribosomal RNA gene was amplified by polymerase chain reaction (PCR) taking advantage of universal primers that can amplify the gene of almost all bacterial species, and the amplicons were cloned and sequenced. Sequence homology with specific bacterial species was analyzed by database research. Bacterial contamination at every step of the bile sampling, DNA extraction and PCR study was avoided. Furthermore, to confirm whether bacterial DNA is detectable in liver explants, the same analysis was performed using 10 liver explants of patients with primary biliary cirrhosis. In primary biliary cirrhosis, 75% (p<0.0001) of 100 clones were identified as so-called gram-positive cocci while these cocci were positive in only 5% in cholecystolithiasis (p<0.0001). In cholecystolithiasis gram-negative rods were predominant instead. One bacterial species detected in a normal adult was not related to those detected in primary biliary cirrhosis and cholecystolithiasis patients. No bacterial DNA was detected by PCR amplification in 10 liver explants of patients with primary biliary cirrhosis. The present results raise several possible roles of gram-positive bacteria in bile in the etiopathogenesis of primary biliary cirrhosis. However, these results could also reflect an epiphenomenon due to decreased bile flow in the

Bacterial RNA Biology on a Genome Scale.

PubMed

Hör, Jens; Gorski, Stanislaw A; Vogel, Jörg

2018-06-07

Bacteria are an exceedingly diverse group of organisms whose molecular exploration is experiencing a renaissance. While the classical view of bacterial gene expression was relatively simple, the emerging view is more complex, encompassing extensive post-transcriptional control involving riboswitches, RNA thermometers, and regulatory small RNAs (sRNAs) associated with the RNA-binding proteins CsrA, Hfq, and ProQ, as well as CRISPR/Cas systems that are programmed by RNAs. Moreover, increasing interest in members of the human microbiota and environmental microbial communities has highlighted the importance of understudied bacterial species with largely unknown transcriptome structures and RNA-based control mechanisms. Collectively, this creates a need for global RNA biology approaches that can rapidly and comprehensively analyze the RNA composition of a bacterium of interest. We review such approaches with a focus on RNA-seq as a versatile tool to investigate the different layers of gene expression in which RNA is made, processed, regulated, modified, translated, and turned over. Copyright © 2017 Elsevier Inc. All rights reserved.

Concurrent host-pathogen gene expression in the lungs of pigs challenged with Actinobacillus pleuropneumoniae.

PubMed

Brogaard, Louise; Klitgaard, Kirstine; Heegaard, Peter M H; Hansen, Mette Sif; Jensen, Tim Kåre; Skovgaard, Kerstin

2015-05-28

Actinobacillus pleuropneumoniae causes pleuropneumonia in pigs, a disease which is associated with high morbidity and mortality, as well as impaired animal welfare. To obtain in-depth understanding of this infection, the interplay between virulence factors of the pathogen and defense mechanisms of the porcine host needs to be elucidated. However, research has traditionally focused on either bacteriology or immunology; an unbiased picture of the transcriptional responses can be obtained by investigating both organisms in the same biological sample. Host and pathogen responses in pigs experimentally infected with A. pleuropneumoniae were analyzed by high-throughput RT-qPCR. This approach allowed concurrent analysis of selected genes encoding proteins known or hypothesized to be important in the acute phase of this infection. The expression of 17 bacterial and 31 porcine genes was quantified in lung samples obtained within the first 48 hours of infection. This provided novel insight into the early time course of bacterial genes involved in synthesis of pathogen-associated molecular patterns (lipopolysaccharide, peptidoglycan, lipoprotein) and genes involved in pattern recognition (TLR4, CD14, MD2, LBP, MYD88) in response to A. pleuropneumoniae. Significant up-regulation of proinflammatory cytokines such as IL1B, IL6, and IL8 was observed, correlating with protein levels, infection status and histopathological findings. Host genes encoding proteins involved in iron metabolism, as well as bacterial genes encoding exotoxins, proteins involved in adhesion, and iron acquisition were found to be differentially expressed according to disease progression. By applying laser capture microdissection, porcine expression of selected genes could be confirmed in the immediate surroundings of the invading pathogen. Microbial pathogenesis is the product of interactions between host and pathogen. Our results demonstrate the applicability of high-throughput RT-qPCR for the elucidation

Themes and Variations: Regulation of RpoN-Dependent Flagellar Genes across Diverse Bacterial Species

PubMed Central

Tsang, Jennifer; Hoover, Timothy R.

2014-01-01

Flagellar biogenesis in bacteria is a complex process in which the transcription of dozens of structural and regulatory genes is coordinated with the assembly of the flagellum. Although the overall process of flagellar biogenesis is conserved among bacteria, the mechanisms used to regulate flagellar gene expression vary greatly among different bacterial species. Many bacteria use the alternative sigma factor σ 54 (also known as RpoN) to transcribe specific sets of flagellar genes. These bacteria include members of the Epsilonproteobacteria (e.g., Helicobacter pylori and Campylobacter jejuni), Gammaproteobacteria (e.g., Vibrio and Pseudomonas species), and Alphaproteobacteria (e.g., Caulobacter crescentus). This review characterizes the flagellar transcriptional hierarchies in these bacteria and examines what is known about how flagellar gene regulation is linked with other processes including growth phase, quorum sensing, and host colonization. PMID:24672734

Presence or Absence of mlr Genes and Nutrient Concentrations Co-Determine the Microcystin Biodegradation Efficiency of a Natural Bacterial Community

PubMed Central

Lezcano, María Ángeles; Morón-López, Jesús; Agha, Ramsy; López-Heras, Isabel; Nozal, Leonor; Quesada, Antonio; El-Shehawy, Rehab

2016-01-01

The microcystin biodegradation potential of a natural bacterial community coexisting with a toxic cyanobacterial bloom was investigated in a water reservoir from central Spain. The biodegradation capacity was confirmed in all samples during the bloom and an increase of mlrA gene copies was found with increasing microcystin concentrations. Among the 24 microcystin degrading strains isolated from the bacterial community, only 28% showed presence of mlrA gene, strongly supporting the existence and abundance of alternative microcystin degradation pathways in nature. In vitro degradation assays with both mlr+ and mlr− bacterial genotypes (with presence and absence of the complete mlr gene cluster, respectively) were performed with four isolated strains (Sphingopyxis sp. IM-1, IM-2 and IM-3; Paucibacter toxinivorans IM-4) and two bacterial degraders from the culture collection (Sphingosinicella microcystinivorans Y2; Paucibacter toxinivorans 2C20). Differences in microcystin degradation efficiencies between genotypes were found under different total organic carbon and total nitrogen concentrations. While mlr+ strains significantly improved microcystin degradation rates when exposed to other carbon and nitrogen sources, mlr− strains showed lower degradation efficiencies. This suggests that the presence of alternative carbon and nitrogen sources possibly competes with microcystins and impairs putative non-mlr microcystin degradation pathways. Considering the abundance of the mlr− bacterial population and the increasing frequency of eutrophic conditions in aquatic systems, further research on the diversity of this population and the characterization and conditions affecting non-mlr degradation pathways deserves special attention. PMID:27827872

Presence or Absence of mlr Genes and Nutrient Concentrations Co-Determine the Microcystin Biodegradation Efficiency of a Natural Bacterial Community.

PubMed

Lezcano, María Ángeles; Morón-López, Jesús; Agha, Ramsy; López-Heras, Isabel; Nozal, Leonor; Quesada, Antonio; El-Shehawy, Rehab

2016-11-03

The microcystin biodegradation potential of a natural bacterial community coexisting with a toxic cyanobacterial bloom was investigated in a water reservoir from central Spain. The biodegradation capacity was confirmed in all samples during the bloom and an increase of mlr A gene copies was found with increasing microcystin concentrations. Among the 24 microcystin degrading strains isolated from the bacterial community, only 28% showed presence of mlr A gene, strongly supporting the existence and abundance of alternative microcystin degradation pathways in nature. In vitro degradation assays with both mlr ⁺ and mlr - bacterial genotypes (with presence and absence of the complete mlr gene cluster, respectively) were performed with four isolated strains ( Sphingopyxis sp. IM-1, IM-2 and IM-3; Paucibacter toxinivorans IM-4) and two bacterial degraders from the culture collection ( Sphingosinicella microcystinivorans Y2; Paucibacter toxinivorans 2C20). Differences in microcystin degradation efficiencies between genotypes were found under different total organic carbon and total nitrogen concentrations. While mlr ⁺ strains significantly improved microcystin degradation rates when exposed to other carbon and nitrogen sources, mlr - strains showed lower degradation efficiencies. This suggests that the presence of alternative carbon and nitrogen sources possibly competes with microcystins and impairs putative non- mlr microcystin degradation pathways. Considering the abundance of the mlr - bacterial population and the increasing frequency of eutrophic conditions in aquatic systems, further research on the diversity of this population and the characterization and conditions affecting non- mlr degradation pathways deserves special attention.

GPo1 alkB gene expression for improvement of the degradation of diesel oil by a bacterial consortium.

PubMed

Luo, Qun; He, Ying; Hou, Deng-Yong; Zhang, Jian-Guo; Shen, Xian-Rong

2015-01-01

To facilitate the biodegradation of diesel oil, an oil biodegradation bacterial consortium was constructed. The alkane hydroxylase (alkB) gene of Pseudomonas putida GPo1 was constructed in a pCom8 expression vector, and the pCom8-GPo1 alkB plasmid was transformed into Escherichia coli DH5α. The AlkB protein was expressed by diesel oil induction and detected through SDS-polyacrylamide gel electrophoresis. The culture of the recombinant (pCom8-GPo1 alkB/E. coli DH5α) with the oil biodegradation bacterial consortium increased the degradation ratio of diesel oil at 24 h from 31% to 50%, and the facilitation rates were increased as the proportion of pCom8-GPo1 alkB/E. coli DH5α to the consortium increased. The results suggested that the expression of the GPo1 gene in E. coli DH5α could enhance the function of diesel oil degradation by the bacterial consortium.

GPo1 alkB gene expression for improvement of the degradation of diesel oil by a bacterial consortium

PubMed Central

Luo, Qun; He, Ying; Hou, Deng-Yong; Zhang, Jian-Guo; Shen, Xian-Rong

2015-01-01

To facilitate the biodegradation of diesel oil, an oil biodegradation bacterial consortium was constructed. The alkane hydroxylase (alkB) gene of Pseudomonas putida GPo1 was constructed in a pCom8 expression vector, and the pCom8-GPo1 alkB plasmid was transformed into Escherichia coli DH5α. The AlkB protein was expressed by diesel oil induction and detected through SDS-polyacrylamide gel electrophoresis. The culture of the recombinant (pCom8-GPo1 alkB/E. coli DH5α) with the oil biodegradation bacterial consortium increased the degradation ratio of diesel oil at 24 h from 31% to 50%, and the facilitation rates were increased as the proportion of pCom8-GPo1 alkB/E. coli DH5α to the consortium increased. The results suggested that the expression of the GPo1 gene in E. coli DH5α could enhance the function of diesel oil degradation by the bacterial consortium. PMID:26413044

Abundance of genes involved in mercury methylation in oceanic environments

NASA Astrophysics Data System (ADS)

Palumbo, A. V.; Podar, M.; Gilmour, C. C.; Brandt, C. C.; Brown, S. D.; Crable, B. R.; Weighill, D.; Jacobson, D. A.; Somenahally, A. C.; Elias, D. A.

2016-02-01

The distribution and diversity of genes involved in mercury methylation in oceanic environments is of interest in determining the source of mercury in ocean environments and may have predictive value for mercury methylation rates. The highly conserved hgcAB genes involved in mercury methylation provide an avenue for evaluating the genetic potential for mercury methylation. The genes are sporadically present in a few diverse groups of bacteria and Archaea including Deltaproteobacteria, Firmicutes and Archaea and of over 7000 sequenced species they are only present in about 100 genomes. Examination of sequence data from methylators and non-methylators indicates that these genes are associated with other genes involved in metal transformations and transport. We examined hgcAB presence in over 3500 microbial metagenomes (from all environments) and found the hgcAB genes were present in anaerobic oceanic environments but not in aerobic layers of the open ocean. The genes were common in sediments from marine, coastal and estuarine sources as well as polluted environments. The genes were rare, found in 7 of 138 samples, in metagenomes from the pelagic water column including profiles though the oxygen minimum zone. Other oxic and sub-oxic coastal waters also demonstrated a lack of hgcAB genes including the OMZ in the Eastern North Pacific Ocean. There were some unique hgcA like unique sequences found in metagenomes from depth in the Pacific and Southern Atlantic Ocean. Coastal "dead zone" waters may be important sources of MeHg as the hgcAB genes were abundant in the anoxic waters of a stratified fjord. The genes were absent in microbiomes from vertebrates but were in invertebrate microbiomes However, oceanic species were underrepresented in these samples. Climate change could provide an additional flux of MeHg to the oceans as we found the most abundant representation of hgcAB genes in arctic permafrost. Thus warming could increase flux of methyl mercury to arctic waters.

Involvement of Sp1 in butyric acid-induced HIV-1 gene expression.

PubMed

Imai, Kenichi; Okamoto, Takashi; Ochiai, Kuniyasu

2015-01-01

The ability of human immunodeficiency virus-1(HIV-1) to establish latent infection and its re-activation is considered critical for progression of HIV-1 infection. We previously reported that a bacterial metabolite butyric acid, acting as a potent inhibitor of histone deacetylases (HDACs), could lead to induction of HIV-1 transcription; however, the molecular mechanism remains unclear. The aim of this study was to investigate the effect of butyric acid on HIV-1 gene expression. Butyric acid-mediated HIV-1 gene expression was determined by luciferase assay and Chromatin immunoprecipitation assay. Western blot analysis and ELISA were used for the detection of HIV-1. We found that Sp1 binding sites within the HIV-1 promoter are primarily involved in butyric acid-mediated HIV-1 activation. In fact, Sp1 knockdown by small interfering RNA and the Sp1 inhibitor mithramycin A abolished the effect of butyric acid. We also observed that cAMP response element-binding-binding protein (CBP) was required for butyric acid-induced HIV-1 activation. These results suggest that butyric acid stimulates HIV-1 promoter through inhibition of the Sp1-associated HDAC activity and recruitment of CBP to the HIV-1 LTR. Our findings suggest that Sp1 should be considered as one of therapeutic targets in anti-viral therapy against HIV-1 infection aggravated by butyric acid-producing bacteria. © 2015 S. Karger AG, Basel.

Identification of a new steroid degrading bacterial strain H5 from the Baltic Sea and isolation of two estradiol inducible genes.

PubMed

Sang, Yingying; Xiong, Guangming; Maser, Edmund

2012-03-01

The presence of steroid hormones in the aquatic environment is potentially threatening the population dynamics of all kinds of sea animals and public health. Environmental estrogens in water have been reported to be associated with abnormal sexual development and abnormal feminizing responses in some animals. New approaches for the bioremediation of steroid hormones from the environment are therefore urgently sought. We have previously isolated a steroid degrading bacterial strain (H5) from the Baltic Sea, at Kiel, Germany. In the present investigation, 16S rRNA analysis showed that marine strain H5 belongs to the genus Vibrio, family Vibrionaceae and class Gamma-Proteobacteria. To enable identification of steroid inducible genes from bacterial strain H5, a library was constructed of H5 chromosomal DNA fragments cloned into a fluorescent reporter (pKEGFP-2). A reporter plasmid pK3α-4.6-EGFP3 containing the estrogen-inducible gene 3α-hydroxysteroid dehydrogenase/carbonyl reductase (3α-HSD/CR) from Comamonas testosteroni (C. testosteroni) was created as a positive control. Steroid induction could be detected by a microplate fluorescence reader, when the plasmids were transformed into Escherichia coli (E. coli) HB101 cells. With our meta-genomic pKEGFP-2 approach, we identified two estradiol-inducible genes from marine strain H5, which are obviously involved in steroid degradation. Sequencing of the pKEGFP-2 inserts and data base research at NCBI revealed that one gene corresponds to 3-ketosteroid-delta-1-dehydrogenase from several Mycobacterium strains, while the other showed high similarity to carboxylesterase in Sebadella termitidis and Brachyspira murdochii. Both 3-ketosteroid-delta-1-dehydrogenase and carboxylesterase are one of the first enzymes in steroid degradation. In addition, we identified a strain H5 specific DNA sequence of 480bp which allows sensitive PCR detection and quantification of strain H5 bacteria in "unknown" seawater samples. Currently, the

Virus-induced gene silencing (VIGS)-mediated functional characterization of two genes involved in lignocellulosic secondary cell wall formation.

PubMed

Pandey, Shashank K; Nookaraju, Akula; Fujino, Takeshi; Pattathil, Sivakumar; Joshi, Chandrashekhar P

2016-11-01

Functional characterization of two tobacco genes, one involved in xylan synthesis and the other, a positive regulator of secondary cell wall formation, is reported. Lignocellulosic secondary cell walls (SCW) provide essential plant materials for the production of second-generation bioethanol. Therefore, thorough understanding of the process of SCW formation in plants is beneficial for efficient bioethanol production. Recently, we provided the first proof-of-concept for using virus-induced gene silencing (VIGS) approach for rapid functional characterization of nine genes involved in cellulose, hemicellulose and lignin synthesis during SCW formation. Here, we report VIGS-mediated functional characterization of two tobacco genes involved in SCW formation. Stems of VIGS plants silenced for both selected genes showed increased amount of xylem formation but thinner cell walls than controls. These results were further confirmed by production of stable transgenic tobacco plants manipulated in expression of these genes. Stems of stable transgenic tobacco plants silenced for these two genes showed increased xylem proliferation with thinner walls, whereas transgenic tobacco plants overexpressing these two genes showed increased fiber cell wall thickness but no change in xylem proliferation. These two selected genes were later identified as possible members of DUF579 family involved in xylan synthesis and KNAT7 transcription factor family involved in positive regulation of SCW formation, respectively. Glycome analyses of cell walls showed increased polysaccharide extractability in 1 M KOH extracts of both VIGS-NbDUF579 and VIGS-NbKNAT7 lines suggestive of cell wall loosening. Also, VIGS-NbDUF579 and VIGS-NbKNAT7 lines showed increased saccharification rates (74.5 and 40 % higher than controls, respectively). All these properties are highly desirable for producing higher quantities of bioethanol from lignocellulosic materials of bioenergy plants.

Transcriptional Response of Selenopolypeptide Genes and Selenocysteine Biosynthesis Machinery Genes in Escherichia coli during Selenite Reduction.

PubMed

Tetteh, Antonia Y; Sun, Katherine H; Hung, Chiu-Yueh; Kittur, Farooqahmed S; Ibeanu, Gordon C; Williams, Daniel; Xie, Jiahua

2014-01-01

Bacteria can reduce toxic selenite into less toxic, elemental selenium (Se(0)), but the mechanism on how bacterial cells reduce selenite at molecular level is still not clear. We used Escherichia coli strain K12, a common bacterial strain, as a model to study its growth response to sodium selenite (Na2SeO3) treatment and then used quantitative real-time PCR (qRT-PCR) to quantify transcript levels of three E. coli selenopolypeptide genes and a set of machinery genes for selenocysteine (SeCys) biosynthesis and incorporation into polypeptides, whose involvements in the selenite reduction are largely unknown. We determined that 5 mM Na2SeO3 treatment inhibited growth by ∼ 50% while 0.001 to 0.01 mM treatments stimulated cell growth by ∼ 30%. Under 50% inhibitory or 30% stimulatory Na2SeO3 concentration, selenopolypeptide genes (fdnG, fdoG, and fdhF) whose products require SeCys but not SeCys biosynthesis machinery genes were found to be induced ≥2-fold. In addition, one sulfur (S) metabolic gene iscS and two previously reported selenite-responsive genes sodA and gutS were also induced ≥2-fold under 50% inhibitory concentration. Our findings provide insight about the detoxification of selenite in E. coli via induction of these genes involved in the selenite reduction process.

Diversity of Total Bacterial Communities and Chemoautotrophic Populations in Sulfur-Rich Sediments of Shallow-Water Hydrothermal Vents off Kueishan Island, Taiwan.

PubMed

Wang, Li; Cheung, Man Kit; Liu, Rulong; Wong, Chong Kim; Kwan, Hoi Shan; Hwang, Jiang-Shiou

2017-04-01

Shallow-water hydrothermal vents (HTVs) are an ecologically important habitat with a geographic origin similar to that of deep-sea HTVs. Studies on shallow-water HTVs have not only facilitated understanding of the influences of vents on local ecosystems but also helped to extend the knowledge on deep-sea vents. In this study, the diversity of bacterial communities in the sediments of shallow-water HTVs off Kueishan Island, Taiwan, was investigated by examining the 16S ribosomal RNA gene as well as key functional genes involved in chemoautotrophic carbon fixation (aclB, cbbL and cbbM). In the vent area, Sulfurovum and Sulfurimonas of Epsilonproteobacteria appeared to dominate the benthic bacterial community. Results of aclB gene analysis also suggested involvement of these bacteria in carbon fixation using the reductive tricarboxylic acid (rTCA) cycle. Analysis of the cbbM gene showed that Alphaproteobacterial members such as the purple non-sulfur bacteria were the major chemoautotrophic bacteria involving in carbon fixation via the Calvin-Benson-Bassham (CBB) cycle. However, they only accounted for <2% of the total bacterial community in the vent area. These findings suggest that the rTCA cycle is the major chemoautotrophic carbon fixation pathway in sediments of the shallow-water HTVs off Kueishan Island.

CCDB: a curated database of genes involved in cervix cancer.

PubMed

Agarwal, Subhash M; Raghav, Dhwani; Singh, Harinder; Raghava, G P S

2011-01-01

The Cervical Cancer gene DataBase (CCDB, http://crdd.osdd.net/raghava/ccdb) is a manually curated catalog of experimentally validated genes that are thought, or are known to be involved in the different stages of cervical carcinogenesis. In spite of the large women population that is presently affected from this malignancy still at present, no database exists that catalogs information on genes associated with cervical cancer. Therefore, we have compiled 537 genes in CCDB that are linked with cervical cancer causation processes such as methylation, gene amplification, mutation, polymorphism and change in expression level, as evident from published literature. Each record contains details related to gene like architecture (exon-intron structure), location, function, sequences (mRNA/CDS/protein), ontology, interacting partners, homology to other eukaryotic genomes, structure and links to other public databases, thus augmenting CCDB with external data. Also, manually curated literature references have been provided to support the inclusion of the gene in the database and establish its association with cervix cancer. In addition, CCDB provides information on microRNA altered in cervical cancer as well as search facility for querying, several browse options and an online tool for sequence similarity search, thereby providing researchers with easy access to the latest information on genes involved in cervix cancer.

Genome-wide selective sweeps and gene-specific sweeps in natural bacterial populations

DOE PAGES

Bendall, Matthew L.; Stevens, Sarah L.R.; Chan, Leong-Keat; ...

2016-01-08

Multiple models describe the formation and evolution of distinct microbial phylogenetic groups. These evolutionary models make different predictions regarding how adaptive alleles spread through populations and how genetic diversity is maintained. Processes predicted by competing evolutionary models, for example, genome-wide selective sweeps vs gene-specific sweeps, could be captured in natural populations using time-series metagenomics if the approach were applied over a sufficiently long time frame. Direct observations of either process would help resolve how distinct microbial groups evolve. Using a 9-year metagenomic study of a freshwater lake (2005–2013), we explore changes in single-nucleotide polymorphism (SNP) frequencies and patterns of genemore » gain and loss in 30 bacterial populations. SNP analyses revealed substantial genetic heterogeneity within these populations, although the degree of heterogeneity varied by >1000-fold among populations. SNP allele frequencies also changed dramatically over time within some populations. Interestingly, nearly all SNP variants were slowly purged over several years from one population of green sulfur bacteria, while at the same time multiple genes either swept through or were lost from this population. Furthermore, these patterns were consistent with a genome-wide selective sweep in progress, a process predicted by the ‘ecotype model’ of speciation but not previously observed in nature. In contrast, other populations contained large, SNP-free genomic regions that appear to have swept independently through the populations prior to the study without purging diversity elsewhere in the genome. Finally, evidence for both genome-wide and gene-specific sweeps suggests that different models of bacterial speciation may apply to different populations coexisting in the same environment.« less

Both msa genes in Renibacterium salmoninarum are needed for full virulence in bacterial kidney disease

USGS Publications Warehouse

Coady, A.M.; Murray, A.L.; Elliott, D.G.; Rhodes, L.D.

2006-01-01

Renibacterium salmoninarum, a gram-positive diplococcobacillus that causes bacterial kidney disease among salmon and trout, has two chromosomal loci encoding the major soluble antigen (msa) gene. Because the MSA protein is widely suspected to be an important virulence factor, we used insertion-duplication mutagenesis to generate disruptions of either the msa1 or msa2 gene. Surprisingly, expression of MSA protein in broth cultures appeared unaffected. However, the virulence of either mutant in juvenile Chinook salmon (Oncorhynchus tshawytscha) by intraperitoneal challenge was severely attenuated, suggesting that disruption of the msa1 or msa2 gene affected in vivo expression. Copyright ?? 2006, American Society for Microbiology. All Rights Reserved.

Different impacts of manure and chemical fertilizers on bacterial community structure and antibiotic resistance genes in arable soils.

PubMed

Liu, Peng; Jia, Shuyu; He, Xiwei; Zhang, Xuxiang; Ye, Lin

2017-12-01

Both manure and chemical fertilizers are widely used in modern agriculture. However, the impacts of different fertilizers on bacterial community structure and antibiotic resistance genes (ARGs) in arable soils still remain unclear. In this study, high-throughput sequencing and quantitative PCR were employed to investigate the bacterial community structure, ARGs and mobile genetic elements (MGEs) influenced by the application of different fertilizers, including chemical fertilizers, piggery manure and straw ash. The results showed that the application of fertilizers could significantly change the soil bacterial community and the abundance of Gaiella under phylum Actinobacteria was significantly reduced from 12.9% in unfertilized soil to 4.1%-7.4% in fertilized soil (P < 0.05). It was also found that the application of manure could cause a transient effect on soil resistome composition and the relative abundance of ARGs increased from 7.37 ppm to 32.10 ppm. The abundance of aminoglycoside, sulfonamide and tetracycline resistance genes greatly increased after manure fertilization and then gradually returned to normal levels with the decay of some intestinal bacteria carrying ARGs. In contrast, the application of chemical fertilizers and straw ash significantly changed the bacterial community structure but exerted little effect on soil resistome. Overall, the results of this study illustrated the different effects of different fertilizers on the soil resistome and revealed that the changes of soil resistome induced by manure application mainly resulted from alteration of bacteria community rather than the horizontal gene transfer. Copyright © 2017 Elsevier Ltd. All rights reserved.

Receptors, mediators, and mechanisms involved in bacterial sepsis and septic shock.

PubMed

Van Amersfoort, Edwin S; Van Berkel, Theo J C; Kuiper, Johan

2003-07-01

Bacterial sepsis and septic shock result from the overproduction of inflammatory mediators as a consequence of the interaction of the immune system with bacteria and bacterial wall constituents in the body. Bacterial cell wall constituents such as lipopolysaccharide, peptidoglycans, and lipoteichoic acid are particularly responsible for the deleterious effects of bacteria. These constituents interact in the body with a large number of proteins and receptors, and this interaction determines the eventual inflammatory effect of the compounds. Within the circulation bacterial constituents interact with proteins such as plasma lipoproteins and lipopolysaccharide binding protein. The interaction of the bacterial constituents with receptors on the surface of mononuclear cells is mainly responsible for the induction of proinflammatory mediators by the bacterial constituents. The role of individual receptors such as the toll-like receptors and CD14 in the induction of proinflammatory cytokines and adhesion molecules is discussed in detail. In addition, the roles of a number of other receptors that bind bacterial compounds such as scavenger receptors and their modulating role in inflammation are described. Finally, the therapies for the treatment of bacterial sepsis and septic shock are discussed in relation to the action of the aforementioned receptors and proteins.

Exposure to West Nile Virus Increases Bacterial Diversity and Immune Gene Expression in Culex pipiens.

PubMed

Zink, Steven D; Van Slyke, Greta A; Palumbo, Michael J; Kramer, Laura D; Ciota, Alexander T

2015-10-27

Complex interactions between microbial residents of mosquitoes and arboviruses are likely to influence many aspects of vectorial capacity and could potentially have profound effects on patterns of arbovirus transmission. Such interactions have not been well studied for West Nile virus (WNV; Flaviviridae, Flavivirus) and Culex spp. mosquitoes. We utilized next-generation sequencing of 16S ribosomal RNA bacterial genes derived from Culex pipiens Linnaeus following WNV exposure and/or infection and compared bacterial populations and broad immune responses to unexposed mosquitoes. Our results demonstrate that WNV infection increases the diversity of bacterial populations and is associated with up-regulation of classical invertebrate immune pathways including RNA interference (RNAi), Toll, and Jak-STAT (Janus kinase-Signal Transducer and Activator of Transcription). In addition, WNV exposure alone, without the establishment of infection, results in similar alterations to microbial and immune signatures, although to a lesser extent. Multiple bacterial genera were found in greater abundance inWNV-exposed and/or infected mosquitoes, yet the most consistent and notable was the genus Serratia.

Induction of Xa10-like Genes in Rice Cultivar Nipponbare Confers Disease Resistance to Rice Bacterial Blight.

PubMed

Wang, Jun; Tian, Dongsheng; Gu, Keyu; Yang, Xiaobei; Wang, Lanlan; Zeng, Xuan; Yin, Zhongchao

2017-06-01

Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive bacterial diseases throughout the major rice-growing regions in the world. The rice disease resistance (R) gene Xa10 confers race-specific disease resistance to X. oryzae pv. oryzae strains that deliver the corresponding transcription activator-like (TAL) effector AvrXa10. Upon bacterial infection, AvrXa10 binds specifically to the effector binding element in the promoter of the R gene and activates its expression. Xa10 encodes an executor R protein that triggers hypersensitive response and activates disease resistance. 'Nipponbare' rice carries two Xa10-like genes in its genome, of which one is the susceptible allele of the Xa23 gene, a Xa10-like TAL effector-dependent executor R gene isolated recently from 'CBB23' rice. However, the function of the two Xa10-like genes in disease resistance to X. oryzae pv. oryzae strains has not been investigated. Here, we designated the two Xa10-like genes as Xa10-Ni and Xa23-Ni and characterized their function for disease resistance to rice bacterial blight. Both Xa10-Ni and Xa23-Ni provided disease resistance to X. oryzae pv. oryzae strains that deliver the matching artificially designed TAL effectors (dTALE). Transgenic rice plants containing Xa10-Ni and Xa23-Ni under the Xa10 promoter provided specific disease resistance to X. oryzae pv. oryzae strains that deliver AvrXa10. Xa10-Ni and Xa23-Ni knock-out mutants abolished dTALE-dependent disease resistance to X. oryzae pv. oryzae. Heterologous expression of Xa10-Ni and Xa23-Ni in Nicotiana benthamiana triggered cell death. The 19-amino-acid residues at the N-terminal regions of XA10 or XA10-Ni are dispensable for their function in inducing cell death in N. benthamiana and the C-terminal regions of XA10, XA10-Ni, and XA23-Ni are interchangeable among each other without affecting their function. Like XA10, both XA10-Ni and XA23-Ni locate to the endoplasmic reticulum (ER) membrane

Bacterial species involved in the conversion of dietary flavonoids in the human gut.

PubMed

Braune, Annett; Blaut, Michael

2016-05-03

The gut microbiota plays a crucial role in the conversion of dietary flavonoids and thereby affects their health-promoting effects in the human host. The identification of the bacteria involved in intestinal flavonoid conversion has gained increasing interest. This review summarizes available information on the so far identified human intestinal flavonoid-converting bacterial species and strains as well as their enzymes catalyzing the underlying reactions. The majority of described species involved in flavonoid transformation are capable of carrying out the O-deglycosylation of flavonoids. Other bacteria cleave the less common flavonoid-C-glucosides and/or further degrade the aglycones of flavonols, flavanonols, flavones, flavanones, dihydrochalcones, isoflavones and monomeric flavan-3-ols. To increase the currently limited knowledge in this field, identification of flavonoid-converting bacteria should be continued using culture-dependent screening or isolation procedures and molecular approaches based on sequence information of the involved enzymes.

Novel insights into the response of Atlantic salmon (Salmo salar) to Piscirickettsia salmonis: Interplay of coding genes and lncRNAs during bacterial infection.

PubMed

Valenzuela-Miranda, Diego; Gallardo-Escárate, Cristian

2016-12-01

Despite the high prevalence and impact to Chilean salmon aquaculture of the intracellular bacterium Piscirickettsia salmonis, the molecular underpinnings of host-pathogen interactions remain unclear. Herein, the interplay of coding and non-coding transcripts has been proposed as a key mechanism involved in immune response. Therefore, the aim of this study was to evidence how coding and non-coding transcripts are modulated during the infection process of Atlantic salmon with P. salmonis. For this, RNA-seq was conducted in brain, spleen, and head kidney samples, revealing different transcriptional profiles according to bacterial load. Additionally, while most of the regulated genes annotated for diverse biological processes during infection, a common response associated with clathrin-mediated endocytosis and iron homeostasis was present in all tissues. Interestingly, while endocytosis-promoting factors and clathrin inductions were upregulated, endocytic receptors were mainly downregulated. Furthermore, the regulation of genes related to iron homeostasis suggested an intracellular accumulation of iron, a process in which heme biosynthesis/degradation pathways might play an important role. Regarding the non-coding response, 918 putative long non-coding RNAs were identified, where 425 were newly characterized for S. salar. Finally, co-localization and co-expression analyses revealed a strong correlation between the modulations of long non-coding RNAs and genes associated with endocytosis and iron homeostasis. These results represent the first comprehensive study of putative interplaying mechanisms of coding and non-coding RNAs during bacterial infection in salmonids. Copyright © 2016 Elsevier Ltd. All rights reserved.

Transcriptome of American oysters, Crassostrea virginica, in response to bacterial challenge: insights into potential mechanisms of disease resistance.

PubMed

McDowell, Ian C; Nikapitiya, Chamilani; Aguiar, Derek; Lane, Christopher E; Istrail, Sorin; Gomez-Chiarri, Marta

2014-01-01

The American oyster Crassostrea virginica, an ecologically and economically important estuarine organism, can suffer high mortalities in areas in the Northeast United States due to Roseovarius Oyster Disease (ROD), caused by the gram-negative bacterial pathogen Roseovarius crassostreae. The goals of this research were to provide insights into: 1) the responses of American oysters to R. crassostreae, and 2) potential mechanisms of resistance or susceptibility to ROD. The responses of oysters to bacterial challenge were characterized by exposing oysters from ROD-resistant and susceptible families to R. crassostreae, followed by high-throughput sequencing of cDNA samples from various timepoints after disease challenge. Sequence data was assembled into a reference transcriptome and analyzed through differential gene expression and functional enrichment to uncover genes and processes potentially involved in responses to ROD in the American oyster. While susceptible oysters experienced constant levels of mortality when challenged with R. crassostreae, resistant oysters showed levels of mortality similar to non-challenged oysters. Oysters exposed to R. crassostreae showed differential expression of transcripts involved in immune recognition, signaling, protease inhibition, detoxification, and apoptosis. Transcripts involved in metabolism were enriched in susceptible oysters, suggesting that bacterial infection places a large metabolic demand on these oysters. Transcripts differentially expressed in resistant oysters in response to infection included the immune modulators IL-17 and arginase, as well as several genes involved in extracellular matrix remodeling. The identification of potential genes and processes responsible for defense against R. crassostreae in the American oyster provides insights into potential mechanisms of disease resistance.

Transcriptome of American Oysters, Crassostrea virginica, in Response to Bacterial Challenge: Insights into Potential Mechanisms of Disease Resistance

PubMed Central

McDowell, Ian C.; Nikapitiya, Chamilani; Aguiar, Derek; Lane, Christopher E.; Istrail, Sorin; Gomez-Chiarri, Marta

2014-01-01

The American oyster Crassostrea virginica, an ecologically and economically important estuarine organism, can suffer high mortalities in areas in the Northeast United States due to Roseovarius Oyster Disease (ROD), caused by the gram-negative bacterial pathogen Roseovarius crassostreae. The goals of this research were to provide insights into: 1) the responses of American oysters to R. crassostreae, and 2) potential mechanisms of resistance or susceptibility to ROD. The responses of oysters to bacterial challenge were characterized by exposing oysters from ROD-resistant and susceptible families to R. crassostreae, followed by high-throughput sequencing of cDNA samples from various timepoints after disease challenge. Sequence data was assembled into a reference transcriptome and analyzed through differential gene expression and functional enrichment to uncover genes and processes potentially involved in responses to ROD in the American oyster. While susceptible oysters experienced constant levels of mortality when challenged with R. crassostreae, resistant oysters showed levels of mortality similar to non-challenged oysters. Oysters exposed to R. crassostreae showed differential expression of transcripts involved in immune recognition, signaling, protease inhibition, detoxification, and apoptosis. Transcripts involved in metabolism were enriched in susceptible oysters, suggesting that bacterial infection places a large metabolic demand on these oysters. Transcripts differentially expressed in resistant oysters in response to infection included the immune modulators IL-17 and arginase, as well as several genes involved in extracellular matrix remodeling. The identification of potential genes and processes responsible for defense against R. crassostreae in the American oyster provides insights into potential mechanisms of disease resistance. PMID:25122115

Unique core genomes of the bacterial family vibrionaceae: insights into niche adaptation and speciation.

PubMed

Kahlke, Tim; Goesmann, Alexander; Hjerde, Erik; Willassen, Nils Peder; Haugen, Peik

2012-05-10

The criteria for defining bacterial species and even the concept of bacterial species itself are under debate, and the discussion is apparently intensifying as more genome sequence data is becoming available. However, it is still unclear how the new advances in genomics should be used most efficiently to address this question. In this study we identify genes that are common to any group of genomes in our dataset, to determine whether genes specific to a particular taxon exist and to investigate their potential role in adaptation of bacteria to their specific niche. These genes were named unique core genes. Additionally, we investigate the existence and importance of unique core genes that are found in isolates of phylogenetically non-coherent groups. These groups of isolates, that share a genetic feature without sharing a closest common ancestor, are termed genophyletic groups. The bacterial family Vibrionaceae was used as the model, and we compiled and compared genome sequences of 64 different isolates. Using the software orthoMCL we determined clusters of homologous genes among the investigated genome sequences. We used multilocus sequence analysis to build a host phylogeny and mapped the numbers of unique core genes of all distinct groups of isolates onto the tree. The results show that unique core genes are more likely to be found in monophyletic groups of isolates. Genophyletic groups of isolates, in contrast, are less common especially for large groups of isolate. The subsequent annotation of unique core genes that are present in genophyletic groups indicate a high degree of horizontally transferred genes. Finally, the annotation of the unique core genes of Vibrio cholerae revealed genes involved in aerotaxis and biosynthesis of the iron-chelator vibriobactin. The presented work indicates that genes specific for any taxon inside the bacterial family Vibrionaceae exist. These unique core genes encode conserved metabolic functions that can shed light on the

Metagenomic insights into zooplankton‐associated bacterial communities

PubMed Central

Srivastava, Abhishek; Koski, Marja; Garcia, Juan Antonio L.; Takaki, Yoshihiro; Yokokawa, Taichi; Nunoura, Takuro; Elisabeth, Nathalie H.; Sintes, Eva; Herndl, Gerhard J.

2017-01-01

Summary Zooplankton and microbes play a key role in the ocean's biological cycles by releasing and consuming copious amounts of particulate and dissolved organic matter. Additionally, zooplankton provide a complex microhabitat rich in organic and inorganic nutrients in which bacteria thrive. In this study, we assessed the phylogenetic composition and metabolic potential of microbial communities associated with crustacean zooplankton species collected in the North Atlantic. Using Illumina sequencing of the 16S rRNA gene, we found significant differences between the microbial communities associated with zooplankton and those inhabiting the surrounding seawater. Metagenomic analysis of the zooplankton‐associated microbial community revealed a highly specialized bacterial community able to exploit zooplankton as microhabitat and thus, mediating biogeochemical processes generally underrepresented in the open ocean. The zooplankton‐associated bacterial community is able to colonize the zooplankton's internal and external surfaces using a large set of adhesion mechanisms and to metabolize complex organic compounds released or exuded by the zooplankton such as chitin, taurine and other complex molecules. Moreover, the high number of genes involved in iron and phosphorus metabolisms in the zooplankton‐associated microbiome suggests that this zooplankton‐associated bacterial community mediates specific biogeochemical processes (through the proliferation of specific taxa) that are generally underrepresented in the ambient waters. PMID:28967193

Bacterial lineages putatively associated with the dissemination of antibiotic resistance genes in a full-scale urban wastewater treatment plant.

PubMed

Narciso-da-Rocha, Carlos; Rocha, Jaqueline; Vaz-Moreira, Ivone; Lira, Felipe; Tamames, Javier; Henriques, Isabel; Martinez, José Luis; Manaia, Célia M

2018-06-05

Urban wastewater treatment plants (UWTPs) are reservoirs of antibiotic resistance. Wastewater treatment changes the bacterial community and inevitably impacts the fate of antibiotic resistant bacteria and antibiotic resistance genes (ARGs). Some bacterial groups are major carriers of ARGs and hence, their elimination during wastewater treatment may contribute to increasing resistance removal efficiency. This study, conducted at a full-scale UWTP, evaluated variations in the bacterial community and ARGs loads and explored possible associations among them. With that aim, the bacterial community composition (16S rRNA gene Illumina sequencing) and ARGs abundance (real-time PCR) were characterized in samples of raw wastewater (RWW), secondary effluent (sTWW), after UV disinfection (tTWW), and after a period of 3 days storage to monitoring possible bacterial regrowth (tTWW-RE). Culturable enterobacteria were also enumerated. Secondary treatment was associated with the most dramatic bacterial community variations and coincided with reductions of ~2 log-units in the ARGs abundance. In contrast, no significant changes in the bacterial community composition and ARGs abundance were observed after UV disinfection of sTWW. Nevertheless, after UV treatment, viability losses were indicated ~2 log-units reductions of culturable enterobacteria. The analysed ARGs (qnrS, bla CTX-M , bla OXA-A , bla TEM , bla SHV , sul1, sul2, and intI1) were strongly correlated with taxa more abundant in RWW than in the other types of water, and which associated with humans and animals, such as members of the families Campylobacteraceae, Comamonadaceae, Aeromonadaceae, Moraxellaceae, and Bacteroidaceae. Further knowledge of the dynamics of the bacterial community during wastewater treatment and its relationship with ARGs variations may contribute with information useful for wastewater treatment optimization, aiming at a more effective resistance control. Copyright © 2018 Elsevier Ltd. All rights

Bacterial sex in dental plaque.

PubMed

Olsen, Ingar; Tribble, Gena D; Fiehn, Nils-Erik; Wang, Bing-Yan

2013-01-01

Genes are transferred between bacteria in dental plaque by transduction, conjugation, and transformation. Membrane vesicles can also provide a mechanism for horizontal gene transfer. DNA transfer is considered bacterial sex, but the transfer is not parallel to processes that we associate with sex in higher organisms. Several examples of bacterial gene transfer in the oral cavity are given in this review. How frequently this occurs in dental plaque is not clear, but evidence suggests that it affects a number of the major genera present. It has been estimated that new sequences in genomes established through horizontal gene transfer can constitute up to 30% of bacterial genomes. Gene transfer can be both inter- and intrageneric, and it can also affect transient organisms. The transferred DNA can be integrated or recombined in the recipient's chromosome or remain as an extrachromosomal inheritable element. This can make dental plaque a reservoir for antimicrobial resistance genes. The ability to transfer DNA is important for bacteria, making them better adapted to the harsh environment of the human mouth, and promoting their survival, virulence, and pathogenicity.

Genetic Variation in the β2-Adrenocepter Gene Is Associated with Susceptibility to Bacterial Meningitis in Adults

PubMed Central

Adriani, Kirsten S.; Brouwer, Matthijs C.; Baas, Frank; Zwinderman, Aeilko H.; van der Ende, Arie; van de Beek, Diederik

2012-01-01

Recently, the biased β2-adrenoceptor/β-arrestin pathway was shown to play a pivotal role in crossing of the blood brain barrier by Neisseria meningitidis. We hypothesized that genetic variation in the β2-adrenoceptor gene (ADRB2) may influence susceptibility to bacterial meningitis. In a prospective genetic association study we genotyped 542 patients with CSF culture proven community acquired bacterial meningitis and 376 matched controls for 2 functional single nucleotide polymorphisms in the β2-adrenoceptor gene (ADRB2). Furthermore, we analyzed if the use of non-selective beta-blockers, which bind to the β2-adrenoceptor, influenced the risk of bacterial meningitis. We identified a functional polymorphism in ADRB2 (rs1042714) to be associated with an increased risk for bacterial meningitis (Odds ratio [OR] 1.35, 95% confidence interval [CI] 1.04–1.76; p = 0.026). The association remained significant after correction for age and was more prominent in patients with pneumococcal meningitis (OR 1.52, 95% CI 1.12–2.07; p = 0.007). For meningococcal meningitis the difference in genotype frequencies between patients and controls was similar to that in pneumococcal meningitis, but this was not statistically significant (OR 1.43, 95% CI 0.60–3.38; p = 0.72). Patients with bacterial meningitis had a lower frequency of non-selective beta-blockers use compared to the age matched population (0.9% vs. 1.8%), although this did not reach statistical significance (OR 1.96 [95% CI 0.88–4.39]; p = 0.09). In conclusion, we identified an association between a genetic variant in the β2-adrenoceptor and increased susceptibility to bacterial meningitis. The potential benefit of pharmacological treatment targeting the β2-adrenoceptor to prevent bacterial meningitis in the general population or patients with bacteraemia should be further studied in both experimental studies and observational cohorts. PMID:22624056

Sulfamethoxazole and COD increase abundance of sulfonamide resistance genes and change bacterial community structures within sequencing batch reactors.

PubMed

Guo, Xueping; Pang, Weihai; Dou, Chunling; Yin, Daqiang

2017-05-01

The abundant microbial community in biological treatment processes in wastewater treatment plants (WWTPs) may potentially enhance the horizontal gene transfer of antibiotic resistance genes with the presence of antibiotics. A lab-scale sequencing batch reactor was designed to investigate response of sulfonamide resistance genes (sulI, sulII) and bacterial communities to various concentrations of sulfamethoxazole (SMX) and chemical oxygen demand (COD) of wastewater. The SMX concentrations (0.001 mg/L, 0.1 mg/L and 10 mg/L) decreased with treatment time and higher SMX level was more difficult to remove. The presence of SMX also significantly reduced the removal efficiency of ammonia nitrogen, affecting the normal function of WWTPs. All three concentrations of SMX raised both sulI and sulII genes with higher concentrations exhibiting greater increases. The abundance of sul genes was positive correlated with treatment time and followed the second-order reaction kinetic model. Interestingly, these two genes have rather similar activity. SulI and sulII gene abundance also performed similar response to COD. Simpson index and Shannon-Weiner index did not show changes in the microbial community diversity. However, the 16S rRNA gene cloning and sequencing results showed the bacterial community structures varied during different stages. The results demonstrated that influent antibiotics into WWTPs may facilitate selection of ARGs and affect the wastewater conventional treatment as well as the bacteria community structures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analysis of bacterial xylose isomerase gene diversity using gene-targeted metagenomics.

PubMed

Nurdiani, Dini; Ito, Michihiro; Maruyama, Toru; Terahara, Takeshi; Mori, Tetsushi; Ugawa, Shin; Takeyama, Haruko

2015-08-01

Bacterial xylose isomerases (XI) are promising resources for efficient biofuel production from xylose in lignocellulosic biomass. Here, we investigated xylose isomerase gene (xylA) diversity in three soil metagenomes differing in plant vegetation and geographical location, using an amplicon pyrosequencing approach and two newly-designed primer sets. A total of 158,555 reads from three metagenomic DNA replicates for each soil sample were classified into 1127 phylotypes, detected in triplicate and defined by 90% amino acid identity. The phylotype coverage was estimated to be within the range of 84.0-92.7%. The xylA gene phylotypes obtained were phylogenetically distributed across the two known xylA groups. They shared 49-100% identities with their closest-related XI sequences in GenBank. Phylotypes demonstrating <90% identity with known XIs in the database accounted for 89% of the total xylA phylotypes. The differences among xylA members and compositions within each soil sample were significantly smaller than they were between different soils based on a UniFrac distance analysis, suggesting soil-specific xylA genotypes and taxonomic compositions. The differences among xylA members and their compositions in the soil were strongly correlated with 16S rRNA variation between soil samples, also assessed by amplicon pyrosequencing. This is the first report of xylA diversity in environmental samples assessed by amplicon pyrosequencing. Our data provide information regarding xylA diversity in nature, and can be a basis for the screening of novel xylA genotypes for practical applications. Copyright © 2015. Published by Elsevier B.V.

Combining gene expression and genetic analyses to identify candidate genes involved in cold responses in pea.

PubMed

Legrand, Sylvain; Marque, Gilles; Blassiau, Christelle; Bluteau, Aurélie; Canoy, Anne-Sophie; Fontaine, Véronique; Jaminon, Odile; Bahrman, Nasser; Mautord, Julie; Morin, Julie; Petit, Aurélie; Baranger, Alain; Rivière, Nathalie; Wilmer, Jeroen; Delbreil, Bruno; Lejeune-Hénaut, Isabelle

2013-09-01

Cold stress affects plant growth and development. In order to better understand the responses to cold (chilling or freezing tolerance), we used two contrasted pea lines. Following a chilling period, the Champagne line becomes tolerant to frost whereas the Terese line remains sensitive. Four suppression subtractive hybridisation libraries were obtained using mRNAs isolated from pea genotypes Champagne and Terese. Using quantitative polymerase chain reaction (qPCR) performed on 159 genes, 43 and 54 genes were identified as differentially expressed at the initial time point and during the time course study, respectively. Molecular markers were developed from the differentially expressed genes and were genotyped on a population of 164 RILs derived from a cross between Champagne and Terese. We identified 5 candidate genes colocalizing with 3 different frost damage quantitative trait loci (QTL) intervals and a protein quantity locus (PQL) rich region previously reported. This investigation revealed the role of constitutive differences between both genotypes in the cold responses, in particular with genes related to glycine degradation pathway that could confer to Champagne a better frost tolerance. We showed that freezing tolerance involves a decrease of expression of genes related to photosynthesis and the expression of a gene involved in the production of cysteine and methionine that could act as cryoprotectant molecules. Although it remains to be confirmed, this study could also reveal the involvement of the jasmonate pathway in the cold responses, since we observed that two genes related to this pathway were mapped in a frost damage QTL interval and in a PQL rich region interval, respectively. Copyright © 2013 Elsevier GmbH. All rights reserved.

Dynamics of fecal indicator bacteria, bacterial pathogen genes, and organic wastewater contaminants in the Little Calumet River: Portage Burns Waterway, Indiana

USGS Publications Warehouse

Haack, Sheridan K.; Duris, Joseph W.

2013-01-01

Little information exists on the co-occurrence of fecal indicator bacteria (FIB), bacterial pathogens, and organic wastewater-associated chemicals (OWCs) within Great Lakes tributaries. Fifteen watershed sites and one beach site adjacent to the Little Calumet River–Portage Burns Waterway (LCRPBW) on Lake Michigan were tested on four dates for pH, dissolved oxygen, specific conductance, chloride, color, ammonia- and nitrate-nitrogen, soluble phosphorus, sulfate, turbidity, and atrazine; for concentrations of FIB; and for genes indicating the presence of human-pathogenic enterococci (ENT) and of Shiga-toxin producing Escherichia coli (EC) from various animal sources. Nineteen samples were also tested for 60 OWCs. Half of the watershed samples met EC recreational water quality standards; none met ENT standards. Human-wastewater-associated OWC detections were correlated with human-influence indicators such as population/km2, chloride concentrations, and the presence of WWTP effluents, but EC and ENT concentrations were not. Bacterial pathogen genes indicated rural human and several potential animal sources. OWCs of human or ecosystem health concern (musk fragrances AHTN and HHCB, alkylphenols, carbamazepine) and 3 bacterial pathogen genes were detected at the mouth of the LCRPBW, but no such OWCs and only 1 pathogen gene were detected at the beach. The LCRPBW has significant potential to deliver FIB, potential bacterial pathogens, and OWCs of human or ecosystem health concern to the nearshore of Lake Michigan, under conditions enhancing nearshore transport of the river plume. Nearshore mixing of lake and river water, and the lack of relationship between OWCs and FIB or pathogen genes, pose numerous challenges for watershed and nearshore assessment and remediation.

Bacterial genes mutL, mutS, and dcm participate in repair of mismatches at 5-methylcytosine sites.

PubMed Central

Lieb, M

1987-01-01

Certain amber mutations in the cI gene of bacteriophage lambda appear to recombine very frequently with nearby mutations. The aberrant mutations included C-to-T transitions at the second cytosine in 5'CC(A/T)GG sequences (which are subject to methylation by bacterial cytosine methylase) and in 5'CCAG and 5'CAGG sequences. Excess cI+ recombinants arising in crosses that utilize these mutations are attributable to the correction of mismatches by a bacterial very-short-patch (VSP) mismatch repair system. In the present study I found that two genes required for methyladenine-directed (long-patch) mismatch repair, mutL and mutS, also functioned in VSP mismatch repair; mutH and mutU (uvrD) were dispensable. VSP mismatch repair was greatly reduced in a dcm Escherichia coli mutant, in which 5-methylcytosine was not methylated. However, mismatches in heteroduplexes prepared from lambda DNA lacking 5-methylcytosine were repaired in dcm+ bacteria. These results indicate that the product of gene dcm has a repair function in addition to its methylase activity. PMID:2959653

INFLUENCE OF ROOT EXUDATES AND BACTERIAL METABOLIC ACTIVITY ON APPARENT CONJUGAL GENE TRANSFER FREQUENCIES IN THE RHIZOSPHERE OF WATER GRASS (ECHINOCLORA CRUSGALLI)

EPA Science Inventory

The premise that genetic exchange is primarily localized in niches characterized by dense bacterial populations and high availability of growth substrates was tested by relating conjugal gene transfer of an RP4 derivative to availability of root exudates and bacterial metabolic a...

Addition of transcription activator-like effector binding sites to a pathogen strain-specific rice bacterial blight resistance gene makes it effective against additional strains and against bacterial leaf streak.

PubMed

Hummel, Aaron W; Doyle, Erin L; Bogdanove, Adam J

2012-09-01

Xanthomonas transcription activator-like (TAL) effectors promote disease in plants by binding to and activating host susceptibility genes. Plants counter with TAL effector-activated executor resistance genes, which cause host cell death and block disease progression. We asked whether the functional specificity of an executor gene could be broadened by adding different TAL effector binding elements (EBEs) to it. We added six EBEs to the rice Xa27 gene, which confers resistance to strains of the bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo) that deliver the TAL effector AvrXa27. The EBEs correspond to three other effectors from Xoo strain PXO99(A) and three from strain BLS256 of the bacterial leaf streak pathogen Xanthomonas oryzae pv. oryzicola (Xoc). Stable integration into rice produced healthy lines exhibiting gene activation by each TAL effector, and resistance to PXO99(A) , a PXO99(A) derivative lacking AvrXa27, and BLS256, as well as two other Xoo and 10 Xoc strains virulent toward wildtype Xa27 plants. Transcripts initiated primarily at a common site. Sequences in the EBEs were found to occur nonrandomly in rice promoters, suggesting an overlap with endogenous regulatory sequences. Thus, executor gene specificity can be broadened by adding EBEs, but caution is warranted because of the possible coincident introduction of endogenous regulatory elements. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

Genomic analyses of bacterial porin-cytochrome gene clusters

DOE PAGES

Shi, Liang; Fredrickson, James K.; Zachara, John M.

2014-11-26

In this study, the porin-cytochrome (Pcc) protein complex is responsible for trans-outer membrane electron transfer during extracellular reduction of Fe(III) by the dissimilatory metal-reducing bacterium Geobacter sulfurreducens PCA. The identified and characterized Pcc complex of G. sulfurreducens PCA consists of a porin-like outer-membrane protein, a periplasmic 8-heme c type cytochrome (c-Cyt) and an outer-membrane 12-heme c-Cyt, and the genes encoding the Pcc proteins are clustered in the same regions of genome (i.e., the pcc gene clusters) of G. sulfurreducens PCA. A survey of additionally microbial genomes has identified the pcc gene clusters in all sequenced Geobacter spp. and other bacteriamore » from six different phyla, including Anaeromyxobacter dehalogenans 2CP-1, A. dehalogenans 2CP-C, Anaeromyxobacter sp. K, Candidatus Kuenenia stuttgartiensis, Denitrovibrio acetiphilus DSM 12809, Desulfurispirillum indicum S5, Desulfurivibrio alkaliphilus AHT2, Desulfurobacterium thermolithotrophum DSM 11699, Desulfuromonas acetoxidans DSM 684, Ignavibacterium album JCM 16511, and Thermovibrio ammonificans HB-1. The numbers of genes in the pcc gene clusters vary, ranging from two to nine. Similar to the metal-reducing (Mtr) gene clusters of other Fe(III)-reducing bacteria, such as Shewanella spp., additional genes that encode putative c-Cyts with predicted cellular localizations at the cytoplasmic membrane, periplasm and outer membrane often associate with the pcc gene clusters. This suggests that the Pcc-associated c-Cyts may be part of the pathways for extracellular electron transfer reactions. The presence of pcc gene clusters in the microorganisms that do not reduce solid-phase Fe(III) and Mn(IV) oxides, such as D. alkaliphilus AHT2 and I. album JCM 16511, also suggests that some of the pcc gene clusters may be involved in extracellular electron transfer reactions with the substrates other than Fe(III) and Mn(IV) oxides.« less

Variation of nonylphenol-degrading gene abundance and bacterial community structure in bioaugmented sediment microcosm.

PubMed

Wang, Zhao; Yang, Yuyin; Sun, Weimin; Dai, Yu; Xie, Shuguang

2015-02-01

Nonylphenol (NP) can accumulate in river sediment. Bioaugmentation is an attractive option to dissipate heavy NP pollution in river sediment. In this study, two NP degraders were isolated from crude oil-polluted soil and river sediment. Microcosms were constructed to test their ability to degrade NP in river sediment. The shift in the proportion of NP-degrading genes and bacterial community structure in sediment microcosms were characterized using quantitative PCR assay and terminal restriction fragment length polymorphism analysis, respectively. Phylogenetic analysis indicated that the soil isolate belonged to genus Stenotrophomonas, while the sediment isolate was a Sphingobium species. Both of them could almost completely clean up a high level of NP in river sediment (150 mg/kg NP) in 10 or 14 days after inoculation. An increase in the proportion of alkB and sMO genes was observed in sediment microcosms inoculated with Stenotrophomonas strain Y1 and Sphingobium strain Y2, respectively. Moreover, bioaugmentation using Sphingobium strain Y2 could have a strong impact on sediment bacterial community structure, while inoculation of Stenotrophomonas strain Y1 illustrated a weak impact. This study can provide some new insights towards NP biodegradation and bioremediation.

Antibiotic discovery throughout the Small World Initiative: A molecular strategy to identify biosynthetic gene clusters involved in antagonistic activity.

PubMed

Davis, Elizabeth; Sloan, Tyler; Aurelius, Krista; Barbour, Angela; Bodey, Elijah; Clark, Brigette; Dennis, Celeste; Drown, Rachel; Fleming, Megan; Humbert, Allison; Glasgo, Elizabeth; Kerns, Trent; Lingro, Kelly; McMillin, MacKenzie; Meyer, Aaron; Pope, Breanna; Stalevicz, April; Steffen, Brittney; Steindl, Austin; Williams, Carolyn; Wimberley, Carmen; Zenas, Robert; Butela, Kristen; Wildschutte, Hans

2017-06-01

The emergence of bacterial pathogens resistant to all known antibiotics is a global health crisis. Adding to this problem is that major pharmaceutical companies have shifted away from antibiotic discovery due to low profitability. As a result, the pipeline of new antibiotics is essentially dry and many bacteria now resist the effects of most commonly used drugs. To address this global health concern, citizen science through the Small World Initiative (SWI) was formed in 2012. As part of SWI, students isolate bacteria from their local environments, characterize the strains, and assay for antibiotic production. During the 2015 fall semester at Bowling Green State University, students isolated 77 soil-derived bacteria and genetically characterized strains using the 16S rRNA gene, identified strains exhibiting antagonistic activity, and performed an expanded SWI workflow using transposon mutagenesis to identify a biosynthetic gene cluster involved in toxigenic compound production. We identified one mutant with loss of antagonistic activity and through subsequent whole-genome sequencing and linker-mediated PCR identified a 24.9 kb biosynthetic gene locus likely involved in inhibitory activity in that mutant. Further assessment against human pathogens demonstrated the inhibition of Bacillus cereus, Listeria monocytogenes, and methicillin-resistant Staphylococcus aureus in the presence of this compound, thus supporting our molecular strategy as an effective research pipeline for SWI antibiotic discovery and genetic characterization. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

High-Throughput rRNA Gene Sequencing Reveals High
and Complex Bacterial Diversity Associated with
Brazilian Coffee Bean Fermentation

PubMed Central

Vinícius de Melo, Gilberto

2018-01-01

Summary Coffee bean fermentation is a spontaneous, on-farm process involving the action of different microbial groups, including bacteria and fungi. In this study, high-throughput sequencing approach was employed to study the diversity and dynamics of bacteria associated with Brazilian coffee bean fermentation. The total DNA from fermenting coffee samples was extracted at different time points, and the 16S rRNA gene with segments around the V4 variable region was sequenced by Illumina high-throughput platform. Using this approach, the presence of over eighty bacterial genera was determined, many of which have been detected for the first time during coffee bean fermentation, including Fructobacillus, Pseudonocardia, Pedobacter, Sphingomonas and Hymenobacter. The presence of Fructobacillus suggests an influence of these bacteria on fructose metabolism during coffee fermentation. Temporal analysis showed a strong dominance of lactic acid bacteria with over 97% of read sequences at the end of fermentation, mainly represented by the Leuconostoc and Lactococcus. Metabolism of lactic acid bacteria was associated with the high formation of lactic acid during fermentation, as determined by HPLC analysis. The results reported in this study confirm the underestimation of bacterial diversity associated with coffee fermentation. New microbial groups reported in this study may be explored as functional starter cultures for on-farm coffee processing.

Mutation in the pssA gene involved in exopolysaccharide synthesis leads to several physiological and symbiotic defects in Rhizobium leguminosarum bv. trifolii.

PubMed

Janczarek, Monika; Rachwał, Kamila

2013-12-05

The symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum bv. trifolii 24.2 secretes large amounts of acidic exopolysaccharide (EPS), which plays a crucial role in establishment of effective symbiosis with clover. The biosynthesis of this heteropolymer is conducted by a multi-enzymatic complex located in the bacterial inner membrane. PssA protein, responsible for the addition of glucose-1-phosphate to a polyprenyl phosphate carrier, is involved in the first step of EPS synthesis. In this work, we characterize R. leguminosarum bv. trifolii strain Rt270 containing a mini-Tn5 transposon insertion located in the 3'-end of the pssA gene. It has been established that a mutation in this gene causes a pleiotropic effect in rhizobial cells. This is confirmed by the phenotype of the mutant strain Rt270, which exhibits several physiological and symbiotic defects such as a deficiency in EPS synthesis, decreased motility and utilization of some nutrients, decreased sensitivity to several antibiotics, an altered extracellular protein profile, and failed host plant infection. The data of this study indicate that the protein product of the pssA gene is not only involved in EPS synthesis, but also required for proper functioning of Rhizobium leguminosarum bv. trifolii cells.

The yeast MSH1 gene is not involved in DNA repair or recombination during meiosis.

PubMed

Sia, Elaine A; Kirkpatrick, David T

2005-02-03

Six strong homologs of the bacterial MutS DNA mismatch repair (MMR) gene have been identified in the yeast Saccharomyces cerevisiae. With the exception of the MSH1 gene, the involvement of each homolog in DNA repair and recombination during meiosis has been determined previously. Five of the homologs have been demonstrated to act in meiotic DNA repair (MSH2, MSH3, MSH6 and MSH4) and/or meiotic recombination (MSH4 and MSH5). Unfortunately the loss of mitochondrial function that results from deletion of MSH1 disrupts meiotic progression, precluding an analysis of MSH1 function in meiotic DNA repair and recombination. However, the recent identification of two separation-of-function alleles of MSH1 that interfere with protein function but still maintain functional mitochondria allow the meiotic activities of MSH1 to be determined. We show that the G776D and F105A alleles of MSH1 exhibit no defects in meiotic recombination, repair base-base mismatches and large loop mismatches efficiently during meiosis, and have high levels of spore viability. These data indicate that the MSH1 protein, unlike other MutS homologs in yeast, plays no role in DNA repair or recombination during meiosis.

A novel bacterial blight resistance gene from Oryza nivara mapped to 38 kb region on chromosome 4L and transferred to Oryza sativa L.

PubMed

Cheema, Kuljit K; Grewal, Navjit K; Vikal, Yogesh; Sharma, Rajiv; Lore, Jagjeet S; Das, Aparna; Bhatia, Dharminder; Mahajan, Ritu; Gupta, Vikas; Bharaj, Tajinder S; Singh, Kuldeep

2008-10-01

Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv oryzae (Xoo) is one of the major constraints to productivity in South-East Asia. The strategy of using major genes, singly or in combination, continues to be the most effective approach for BB management. Currently, more than two dozen genes have been designated but not all the known genes are effective against all the prevalent pathotypes. The challenge, therefore, is to continue to expand the gene pool of effective and potentially durable resistance genes. Wild species constitute an important reservoir of the resistance genes including BB. An accession of Oryza nivara (IRGC 81825) was found to be resistant to all the seven Xoo pathotypes prevalent in northern states of India. Inheritance and mapping of resistance in O. nivara was studied by using F2, BC2F2, BC3F1 and BC3F2 progenies of the cross involving Oryza sativa cv PR114 and the O. nivara acc. 81825 using the most virulent Xoo pathotype. Genetic analysis of the segregating progenies revealed that the BB resistance in O. nivara was conditioned by a single dominant gene. Bulked segregant analysis (BSA) of F2 population using 191 polymorphic SSR markers identified a approximately 35 centiMorgans (cM) chromosomal region on 4L, bracketed by RM317 and RM562, to be associated with BB resistance. Screening of BC3F1 and BC2F2 progenies and their genotyping with more than 30 polymorphic SSR markers in the region, covering Bacterial artificial chromosome (BAC) clone OSJNBb0085C12, led to mapping of the resistance gene between the STS markers based on annotated genes LOC_Os04g53060 and LOC_Os04g53120, which is approximately 38.4 kb. Since none of the known Xa genes, which are mapped on chromosome 4L, are effective against the Xoo pathotypes tested, the BB resistance gene identified and transferred from O. nivara is novel and is tentatively designated as Xa30(t). Homozygous resistant BC3F3 progenies with smallest introgression region have been identified.

Identification of Bicarbonate as a Trigger and Genes Involved with Extracellular DNA Export in Mycobacterial Biofilms

PubMed Central

Rose, Sasha J.

2016-01-01

ABSTRACT Extracellular DNA (eDNA) is an integral biofilm matrix component of numerous pathogens, including nontuberculous mycobacteria (NTM). Cell lysis is the source of eDNA in certain bacteria, but the source of eDNA remains unidentified for NTM, as well as for other eDNA-containing bacterial species. In this study, conditions affecting eDNA export were examined, and genes involved with the eDNA export mechanism were identified. After a method for monitoring eDNA in real time in undisturbed biofilms was established, different conditions affecting eDNA were investigated. Bicarbonate positively influenced eDNA export in a pH-independent manner in Mycobacterium avium, M. abscessus, and M. chelonae. The surface-exposed proteome of M. avium in eDNA-containing biofilms revealed abundant carbonic anhydrases. Chemical inhibition of carbonic anhydrases with ethoxzolamide significantly reduced eDNA export. An unbiased transposon mutant library screen for eDNA export in M. avium identified many severely eDNA-attenuated mutants, including one not expressing a unique FtsK/SpoIIIE-like DNA-transporting pore, two with inactivation of carbonic anhydrases, and nine with inactivation of genes belonging to a unique genomic region, as well as numerous mutants involved in metabolism and energy production. Complementation of nine mutants that included the FtsK/SpoIIIE and carbonic anhydrase significantly restored eDNA export. Interestingly, several attenuated eDNA mutants have mutations in genes encoding proteins that were found with the surface proteomics, and many more mutations are localized in operons potentially encoding surface proteins. Collectively, our data strengthen the evidence of eDNA export being an active mechanism that is activated by the bacterium responding to bicarbonate. PMID:27923918

Dynamic network reconstruction from gene expression data applied to immune response during bacterial infection.

PubMed

Guthke, Reinhard; Möller, Ulrich; Hoffmann, Martin; Thies, Frank; Töpfer, Susanne

2005-04-15

The immune response to bacterial infection represents a complex network of dynamic gene and protein interactions. We present an optimized reverse engineering strategy aimed at a reconstruction of this kind of interaction networks. The proposed approach is based on both microarray data and available biological knowledge. The main kinetics of the immune response were identified by fuzzy clustering of gene expression profiles (time series). The number of clusters was optimized using various evaluation criteria. For each cluster a representative gene with a high fuzzy-membership was chosen in accordance with available physiological knowledge. Then hypothetical network structures were identified by seeking systems of ordinary differential equations, whose simulated kinetics could fit the gene expression profiles of the cluster-representative genes. For the construction of hypothetical network structures singular value decomposition (SVD) based methods and a newly introduced heuristic Network Generation Method here were compared. It turned out that the proposed novel method could find sparser networks and gave better fits to the experimental data. Reinhard.Guthke@hki-jena.de.

Bacterial diversity and reductive dehalogenase redundancy in a 1,2-dichloroethane-degrading bacterial consortium enriched from a contaminated aquifer

PubMed Central

2010-01-01

Background Bacteria possess a reservoir of metabolic functionalities ready to be exploited for multiple purposes. The use of microorganisms to clean up xenobiotics from polluted ecosystems (e.g. soil and water) represents an eco-sustainable and powerful alternative to traditional remediation processes. Recent developments in molecular-biology-based techniques have led to rapid and accurate strategies for monitoring and identification of bacteria and catabolic genes involved in the degradation of xenobiotics, key processes to follow up the activities in situ. Results We report the characterization of the response of an enriched bacterial community of a 1,2-dichloroethane (1,2-DCA) contaminated aquifer to the spiking with 5 mM lactate as electron donor in microcosm studies. After 15 days of incubation, the microbial community structure was analyzed. The bacterial 16S rRNA gene clone library showed that the most represented phylogenetic group within the consortium was affiliated with the phylum Firmicutes. Among them, known degraders of chlorinated compounds were identified. A reductive dehalogenase genes clone library showed that the community held four phylogenetically-distinct catalytic enzymes, all conserving signature residues previously shown to be linked to 1,2-DCA dehalogenation. Conclusions The overall data indicate that the enriched bacterial consortium shares the metabolic functionality between different members of the microbial community and is characterized by a high functional redundancy. These are fundamental features for the maintenance of the community's functionality, especially under stress conditions and suggest the feasibility of a bioremediation treatment with a potential prompt dehalogenation and a process stability over time. PMID:20170484

MGDB: a comprehensive database of genes involved in melanoma.

PubMed

Zhang, Di; Zhu, Rongrong; Zhang, Hanqian; Zheng, Chun-Hou; Xia, Junfeng

2015-01-01

The Melanoma Gene Database (MGDB) is a manually curated catalog of molecular genetic data relating to genes involved in melanoma. The main purpose of this database is to establish a network of melanoma related genes and to facilitate the mechanistic study of melanoma tumorigenesis. The entries describing the relationships between melanoma and genes in the current release were manually extracted from PubMed abstracts, which contains cumulative to date 527 human melanoma genes (422 protein-coding and 105 non-coding genes). Each melanoma gene was annotated in seven different aspects (General Information, Expression, Methylation, Mutation, Interaction, Pathway and Drug). In addition, manually curated literature references have also been provided to support the inclusion of the gene in MGDB and establish its association with melanoma. MGDB has a user-friendly web interface with multiple browse and search functions. We hoped MGDB will enrich our knowledge about melanoma genetics and serve as a useful complement to the existing public resources. Database URL: http://bioinfo.ahu.edu.cn:8080/Melanoma/index.jsp. © The Author(s) 2015. Published by Oxford University Press.

Phytosterols Play a Key Role in Plant Innate Immunity against Bacterial Pathogens by Regulating Nutrient Efflux into the Apoplast1[C][W][OA

PubMed Central

Wang, Keri; Senthil-Kumar, Muthappa; Ryu, Choong-Min; Kang, Li; Mysore, Kirankumar S.

2012-01-01

Bacterial pathogens colonize a host plant by growing between the cells by utilizing the nutrients present in apoplastic space. While successful pathogens manipulate the plant cell membrane to retrieve more nutrients from the cell, the counteracting plant defense mechanism against nonhost pathogens to restrict the nutrient efflux into the apoplast is not clear. To identify the genes involved in nonhost resistance against bacterial pathogens, we developed a virus-induced gene-silencing-based fast-forward genetics screen in Nicotiana benthamiana. Silencing of N. benthamiana SQUALENE SYNTHASE, a key gene in phytosterol biosynthesis, not only compromised nonhost resistance to few pathovars of Pseudomonas syringae and Xanthomonas campestris, but also enhanced the growth of the host pathogen P. syringae pv tabaci by increasing nutrient efflux into the apoplast. An Arabidopsis (Arabidopsis thaliana) sterol methyltransferase mutant (sterol methyltransferase2) involved in sterol biosynthesis also compromised plant innate immunity against bacterial pathogens. The Arabidopsis cytochrome P450 CYP710A1, which encodes C22-sterol desaturase that converts β-sitosterol to stigmasterol, was dramatically induced upon inoculation with nonhost pathogens. An Arabidopsis Atcyp710A1 null mutant compromised both nonhost and basal resistance while overexpressors of AtCYP710A1 enhanced resistance to host pathogens. Our data implicate the involvement of sterols in plant innate immunity against bacterial infections by regulating nutrient efflux into the apoplast. PMID:22298683

Short term memory of Caenorhabditis elegans against bacterial pathogens involves CREB transcription factor.

PubMed

Prithika, Udayakumar; Vikneswari, Ramaraj; Balamurugan, Krishnaswamy

2017-04-01

One of the key issues pertaining to the control of memory is to respond to a consistently changing environment or microbial niche present in it. Human cyclic AMP response element binding protein (CREB) transcription factor which plays a crucial role in memory has a homolog in C. elegans, crh-1. crh-1 appears to influence memory processes to certain extent by habituation of the host to a particular environment. The discrimination between the pathogen and a non-pathogen is essential for C. elegans in a microbial niche which determines its survival. Training the nematodes in the presence of a virulent pathogen (S. aureus) and an opportunistic pathogen (P. mirabilis) separately exhibits a different behavioural paradigm. This appears to be dependent on the CREB transcription factor. Here we show that C. elegans homolog crh-1 helps in memory response for a short term against the interacting pathogens. Following conditioning of the nematodes to S. aureus and P. mirabilis, the wild type nematodes exhibited a positive response towards the respective pathogens which diminished slowly after 2h. By contrast, the crh-1 deficient nematodes had a defective memory post conditioning. The molecular data reinforces the importance of crh-1 gene in retaining the memory of nematode. Our results also suggest that involvement of neurotransmitters play a crucial role in modulating the memory of the nematode with the assistance of CREB. Therefore, we elucidate that CREB is responsible for the short term memory response in C. elegans against bacterial pathogens. Copyright © 2016 Elsevier GmbH. All rights reserved.

The germin-like protein OsGLP2-1 enhances resistance to fungal blast and bacterial blight in rice.

PubMed

Liu, Qing; Yang, Jianyuan; Yan, Shijuan; Zhang, Shaohong; Zhao, Junliang; Wang, Wenjuan; Yang, Tifeng; Wang, Xiaofei; Mao, Xingxue; Dong, Jingfang; Zhu, Xiaoyuan; Liu, Bin

2016-11-01

This is the first report that GLP gene (OsGLP2-1) is involved in panicle blast and bacterial blight resistance in rice. In addition to its resistance to blast and bacterial blight, OsGLP2-1 has also been reported to co-localize with a QTLs for sheath blight resistance in rice. These suggest that the disease resistance provided by OsGLP2-1 is quantitative and broad spectrum. Its good resistance to these major diseases in rice makes it to be a promising target in rice breeding. Rice (Oryza sativa) blast caused by Magnaporthe oryzae and bacterial blight caused by Xanthomonas oryzae pv. oryzae are the two most destructive rice diseases worldwide. Germin-like protein (GLP) gene family is one of the important defense gene families which have been reported to be involved in disease resistance in plants. Although GLP proteins have been demonstrated to positively regulate leaf blast resistance in rice, their involvement in resistance to panicle blast and bacterial blight, has not been reported. In this study, we reported that one of the rice GLP genes, OsGLP2-1, was significantly induced by blast fungus. Overexpression of OsGLP2-1 quantitatively enhanced resistance to leaf blast, panicle blast and bacterial blight. The temporal and spatial expression analysis revealed that OsGLP2-1is highly expressed in leaves and panicles and sub-localized in the cell wall. Compared with empty vector transformed (control) plants, the OsGLP2-1 overexpressing plants exhibited higher levels of H 2 O 2 both before and after pathogen inoculation. Moreover, OsGLP2-1 was significantly induced by jasmonic acid (JA). Overexpression of OsGLP2-1 induced three well-characterized defense-related genes which are associated in JA-dependent pathway after pathogen infection. Higher endogenous level of JA was also identified in OsGLP2-1 overexpressing plants than in control plants both before and after pathogen inoculation. Together, these results suggest that OsGLP2-1 functions as a positive regulator to

Conserved gene clusters in bacterial genomes provide further support for the primacy of RNA

NASA Technical Reports Server (NTRS)

Siefert, J. L.; Martin, K. A.; Abdi, F.; Widger, W. R.; Fox, G. E.

1997-01-01

Five complete bacterial genome sequences have been released to the scientific community. These include four (eu)Bacteria, Haemophilus influenzae, Mycoplasma genitalium, M. pneumoniae, and Synechocystis PCC 6803, as well as one Archaeon, Methanococcus jannaschii. Features of organization shared by these genomes are likely to have arisen very early in the history of the bacteria and thus can be expected to provide further insight into the nature of early ancestors. Results of a genome comparison of these five organisms confirm earlier observations that gene order is remarkably unpreserved. There are, nevertheless, at least 16 clusters of two or more genes whose order remains the same among the four (eu)Bacteria and these are presumed to reflect conserved elements of coordinated gene expression that require gene proximity. Eight of these gene orders are essentially conserved in the Archaea as well. Many of these clusters are known to be regulated by RNA-level mechanisms in Escherichia coli, which supports the earlier suggestion that this type of regulation of gene expression may have arisen very early. We conclude that although the last common ancestor may have had a DNA genome, it likely was preceded by progenotes with an RNA genome.

Effect of Copper Treatment on the Composition and Function of the Bacterial Community in the Sponge Haliclona cymaeformis

PubMed Central

Tian, Ren-Mao; Wang, Yong; Bougouffa, Salim; Gao, Zhao-Ming; Cai, Lin; Zhang, Wei-Peng; Bajic, Vladimir

2014-01-01

ABSTRACT Marine sponges are the most primitive metazoan and host symbiotic microorganisms. They are crucial components of the marine ecological system and play an essential role in pelagic processes. Copper pollution is currently a widespread problem and poses a threat to marine organisms. Here, we examined the effects of copper treatment on the composition of the sponge-associated bacterial community and the genetic features that facilitate the survival of enriched bacteria under copper stress. The 16S rRNA gene sequencing results showed that the sponge Haliclona cymaeformis harbored symbiotic sulfur-oxidizing Ectothiorhodospiraceae and photosynthetic Cyanobacteria as dominant species. However, these autotrophic bacteria decreased substantially after treatment with a high copper concentration, which enriched for a heterotrophic-bacterium-dominated community. Metagenomic comparison revealed a varied profile of functional genes and enriched functions, including bacterial motility and chemotaxis, extracellular polysaccharide and capsule synthesis, virulence-associated genes, and genes involved in cell signaling and regulation, suggesting short-period mechanisms of the enriched bacterial community for surviving copper stress in the microenvironment of the sponge. Microscopic observation and comparison revealed dynamic bacterial aggregation within the matrix and lysis of sponge cells. The bacteriophage community was also enriched, and the complete genome of a dominant phage was determined, implying that a lytic phage cycle was stimulated by the high copper concentration. This study demonstrated a copper-induced shift in the composition of functional genes of the sponge-associated bacterial community, revealing the selective effect of copper treatment on the functions of the bacterial community in the microenvironment of the sponge. PMID:25370493

The light gene of Drosophila melanogaster encodes a homologue of VPS41, a yeast gene involved in cellular-protein trafficking.

PubMed

Warner, T S; Sinclair, D A; Fitzpatrick, K A; Singh, M; Devlin, R H; Honda, B M

1998-04-01

Mutations in a number of genes affect eye colour in Drosophila melanogaster; some of these "eye-colour" genes have been shown to be involved in various aspects of cellular transport processes. In addition, combinations of viable mutant alleles of some of these genes, such as carnation (car) combined with either light (lt) or deep-orange (dor) mutants, show lethal interactions. Recently, dor was shown to be homologous to the yeast gene PEP3 (VPS18), which is known to be involved in intracellular trafficking. We have undertaken to extend our earlier work on the lt gene, in order to examine in more detail its expression pattern and to characterize its gene product via sequencing of a cloned cDNA. The gene appears to be expressed at relatively high levels in all stages and tissues examined, and shows strong homology to VPS41, a gene involved in cellular-protein trafficking in yeast and higher eukaryotes. Further genetic experiments also point to a role for lt in transport processes: we describe lethal interactions between viable alleles of lt and dor, as well as phenotypic interactions (reductions in eye pigment) between allels of lt and another eye-colour gene, garnet (g), whose gene product has close homology to a subunit of the human adaptor complex, AP-3.

Evolution of the syntrophic interaction between Desulfovibrio vulgaris and Methanosarcina barkeri: involvement of an ancient horizontal gene transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scholten, Johannes C.; Culley, David E.; Brockman, Fred J.

2007-01-05

The sulfate reducing bacteria Desulfovibrio vulgaris and the methanogenic archaea Methanosarcina barkeri can grow syntrophically on lactate. In this study, three functionally unknown genes of D. vulgaris, DVU2103, DVU2104 and DVU2108, were found to be up-regulated 2-4 fold following the lifestyle shift from syntroph to sulfatereducer; moreover, none of these genes were regulated when D. vulgaris was grown alone in various pure culture conditions. These results suggest that these genes may play roles related to the lifestyle change of D. vulgaris from syntroph to sulfate reducer. This hypothesis is further supported by phylogenomic analyses showing that homologies of these genesmore » were only narrowly present in several groups of bacteria, most of which are restricted to a syntrophic life-style, such as Pelobacter carbinolicus, Syntrophobacter fumaroxidans, Syntrophomonas wolfei and Syntrophus aciditrophicus. Phylogenetic analysis showed that the genes tended to be clustered with archaeal genera, and they were rooted on archaeal species in the phylogenetic trees, suggesting that they originated from an archaeal methanogen and were horizontally transferred to a common ancestor of delta- Proteobacteria, Clostridia and Thermotogae. While lost in most species during evolution, these genes appear to have been retained in bacteria capable of syntrophic relationships, probably due to their providing a selective advantage. In addition, no significant bias in codon and amino acid usages was detected between these genes and the rest of the D. vulgaris genome, suggesting these gene transfers may have occurred early in the evolutionary history so that sufficient time has elapsed to allow an adaptation to the codon and amino acid usages of D. vulgaris. This report provides novel insights into the origin and evolution of bacterial genes involved in the syntrophic lifestyle.« less

Emerging contaminants and nutrients synergistically affect the spread of class 1 integron-integrase (intI1) and sul1 genes within stable streambed bacterial communities.

PubMed

Subirats, Jèssica; Timoner, Xisca; Sànchez-Melsió, Alexandre; Balcázar, José Luis; Acuña, Vicenç; Sabater, Sergi; Borrego, Carles M

2018-07-01

Wastewater effluents increase the nutrient load of receiving streams while introducing a myriad of anthropogenic chemical pollutants that challenge the resident aquatic (micro)biota. Disentangling the effects of both kind of stressors and their potential interaction on the dissemination of antibiotic resistance genes in bacterial communities requires highly controlled manipulative experiments. In this work, we investigated the effects of a combined regime of nutrients (at low, medium and high concentrations) and a mixture of emerging contaminants (ciprofloxacin, erythromycin, sulfamethoxazole, diclofenac, and methylparaben) on the bacterial composition, abundance and antibiotic resistance profile of biofilms grown in artificial streams. In particular, we investigated the effect of this combined stress on genes encoding resistance to ciprofloxacin (qnrS), erythromycin (ermB), sulfamethoxazole (sul1 and sul2) as well as the class 1 integron-integrase gene (intI1). Only genes conferring resistance to sulfonamides (sul1 and sul2) and intI1 gene were detected in all treatments during the study period. Besides, bacterial communities exposed to emerging contaminants showed higher copy numbers of sul1 and intI1 genes than those not exposed, whereas nutrient amendments did not affect their abundance. However, bacterial communities exposed to both emerging contaminants and a high nutrient concentration (1, 25 and 1 mg L -1 of phosphate, nitrate and ammonium, respectively) showed the highest increase on the abundance of sul1 and intI1 genes thus suggesting a factors synergistic effect of both stressors. Since none of the treatments caused a significant change on the composition of bacterial communities, the enrichment of sul1 and intI1 genes within the community was caused by their dissemination under the combined pressure exerted by nutrients and emerging contaminants. To the best of our knowledge, this is the first study demonstrating the contribution of nutrients on

Bioinformatics Analysis Reveals Genes Involved in the Pathogenesis of Ameloblastoma and Keratocystic Odontogenic Tumor.

PubMed

Santos, Eliane Macedo Sobrinho; Santos, Hércules Otacílio; Dos Santos Dias, Ivoneth; Santos, Sérgio Henrique; Batista de Paula, Alfredo Maurício; Feltenberger, John David; Sena Guimarães, André Luiz; Farias, Lucyana Conceição

2016-01-01

Pathogenesis of odontogenic tumors is not well known. It is important to identify genetic deregulations and molecular alterations. This study aimed to investigate, through bioinformatic analysis, the possible genes involved in the pathogenesis of ameloblastoma (AM) and keratocystic odontogenic tumor (KCOT). Genes involved in the pathogenesis of AM and KCOT were identified in GeneCards. Gene list was expanded, and the gene interactions network was mapped using the STRING software. "Weighted number of links" (WNL) was calculated to identify "leader genes" (highest WNL). Genes were ranked by K-means method and Kruskal-Wallis test was used (P<0.001). Total interactions score (TIS) was also calculated using all interaction data generated by the STRING database, in order to achieve global connectivity for each gene. The topological and ontological analyses were performed using Cytoscape software and BinGO plugin. Literature review data was used to corroborate the bioinformatics data. CDK1 was identified as leader gene for AM. In KCOT group, results show PCNA and TP53 . Both tumors exhibit a power law behavior. Our topological analysis suggested leader genes possibly important in the pathogenesis of AM and KCOT, by clustering coefficient calculated for both odontogenic tumors (0.028 for AM, zero for KCOT). The results obtained in the scatter diagram suggest an important relationship of these genes with the molecular processes involved in AM and KCOT. Ontological analysis for both AM and KCOT demonstrated different mechanisms. Bioinformatics analyzes were confirmed through literature review. These results may suggest the involvement of promising genes for a better understanding of the pathogenesis of AM and KCOT.

Genes involved in androgen biosynthesis and the male phenotype.

PubMed

Waterman, M R; Keeney, D S

1992-01-01

A series of enzymatic steps in the testis lead to the conversion of cholesterol to the male sex steroid hormones, testosterone and 5 alpha-dihydrotestosterone. Mutations in any one of these steps are presumed to alter or block the development of the male phenotype. Most of the genes encoding the enzymes involved in this pathway have now been cloned, and mutations within the coding regions of these genes do, in fact, block development of the male phenotype.

Linkage of the Nit1C gene cluster to bacterial cyanide assimilation as a nitrogen source.

PubMed

Jones, Lauren B; Ghosh, Pallab; Lee, Jung-Hyun; Chou, Chia-Ni; Kunz, Daniel A

2018-05-21

A genetic linkage between a conserved gene cluster (Nit1C) and the ability of bacteria to utilize cyanide as the sole nitrogen source was demonstrated for nine different bacterial species. These included three strains whose cyanide nutritional ability has formerly been documented (Pseudomonas fluorescens Pf11764, Pseudomonas putida BCN3 and Klebsiella pneumoniae BCN33), and six not previously known to have this ability [Burkholderia (Paraburkholderia) xenovorans LB400, Paraburkholderia phymatum STM815, Paraburkholderia phytofirmans PsJN, Cupriavidus (Ralstonia) eutropha H16, Gluconoacetobacter diazotrophicus PA1 5 and Methylobacterium extorquens AM1]. For all bacteria, growth on or exposure to cyanide led to the induction of the canonical nitrilase (NitC) linked to the gene cluster, and in the case of Pf11764 in particular, transcript levels of cluster genes (nitBCDEFGH) were raised, and a nitC knock-out mutant failed to grow. Further studies demonstrated that the highly conserved nitB gene product was also significantly elevated. Collectively, these findings provide strong evidence for a genetic linkage between Nit1C and bacterial growth on cyanide, supporting use of the term cyanotrophy in describing what may represent a new nutritional paradigm in microbiology. A broader search of Nit1C genes in presently available genomes revealed its presence in 270 different bacteria, all contained within the domain Bacteria, including Gram-positive Firmicutes and Actinobacteria, and Gram-negative Proteobacteria and Cyanobacteria. Absence of the cluster in the Archaea is congruent with events that may have led to the inception of Nit1C occurring coincidentally with the first appearance of cyanogenic species on Earth, dating back 400-500 million years.

Exploring the bacterial gut microbiota of supralittoral talitrid amphipods.

PubMed

Abdelrhman, Khaled F A; Bacci, Giovanni; Marras, Barbara; Nistri, Annamaria; Schintu, Marco; Ugolini, Alberto; Mengoni, Alessio

2017-01-01

Talitrid amphipods (sandhoppers and beach fleas) are typical of the supralittoral zone. They are known to thrive on stranded materials, including detrital marine angiosperms and macroalgae, as well as occasional dead animals. In this work, the gut microbiota of five species of talitrid amphipods (Talitrus saltator, Talorchestia ugolinii, Sardorchestia pelecaniformis, Orchestia montagui and Orchestia stephenseni) collected in Sardinia (Italy) has been investigated through: i) metabarcoding analysis of the amplified 16S rRNA V4 region; and ii) quantification of family 48 glycosyl hydrolase genes (GHF48), involved in cellulose degradation. Results indicate that, though talitrid gut biodiversity is not directly related to taxon or sampling locality, the animals' digestive tracts may host species-specific bacterial communities. In particular, gut microbiota of O. montagui, an inhabitant of Posidonia banquettes and macro-algae mat, showed the greatest differences in taxonomic composition and the highest proportion of GHF48 genes with respect to 16S rRNA genes. These results suggest that the different talitrid species may host species-specific bacterial communities whose function could partially reflect the different microhabitats and food preferences of their host. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

From learning taxonomies to phylogenetic learning: integration of 16S rRNA gene data into FAME-based bacterial classification.

PubMed

Slabbinck, Bram; Waegeman, Willem; Dawyndt, Peter; De Vos, Paul; De Baets, Bernard

2010-01-30

Machine learning techniques have shown to improve bacterial species classification based on fatty acid methyl ester (FAME) data. Nonetheless, FAME analysis has a limited resolution for discrimination of bacteria at the species level. In this paper, we approach the species classification problem from a taxonomic point of view. Such a taxonomy or tree is typically obtained by applying clustering algorithms on FAME data or on 16S rRNA gene data. The knowledge gained from the tree can then be used to evaluate FAME-based classifiers, resulting in a novel framework for bacterial species classification. In view of learning in a taxonomic framework, we consider two types of trees. First, a FAME tree is constructed with a supervised divisive clustering algorithm. Subsequently, based on 16S rRNA gene sequence analysis, phylogenetic trees are inferred by the NJ and UPGMA methods. In this second approach, the species classification problem is based on the combination of two different types of data. Herein, 16S rRNA gene sequence data is used for phylogenetic tree inference and the corresponding binary tree splits are learned based on FAME data. We call this learning approach 'phylogenetic learning'. Supervised Random Forest models are developed to train the classification tasks in a stratified cross-validation setting. In this way, better classification results are obtained for species that are typically hard to distinguish by a single or flat multi-class classification model. FAME-based bacterial species classification is successfully evaluated in a taxonomic framework. Although the proposed approach does not improve the overall accuracy compared to flat multi-class classification, it has some distinct advantages. First, it has better capabilities for distinguishing species on which flat multi-class classification fails. Secondly, the hierarchical classification structure allows to easily evaluate and visualize the resolution of FAME data for the discrimination of bacterial

From learning taxonomies to phylogenetic learning: Integration of 16S rRNA gene data into FAME-based bacterial classification

PubMed Central

2010-01-01

Background Machine learning techniques have shown to improve bacterial species classification based on fatty acid methyl ester (FAME) data. Nonetheless, FAME analysis has a limited resolution for discrimination of bacteria at the species level. In this paper, we approach the species classification problem from a taxonomic point of view. Such a taxonomy or tree is typically obtained by applying clustering algorithms on FAME data or on 16S rRNA gene data. The knowledge gained from the tree can then be used to evaluate FAME-based classifiers, resulting in a novel framework for bacterial species classification. Results In view of learning in a taxonomic framework, we consider two types of trees. First, a FAME tree is constructed with a supervised divisive clustering algorithm. Subsequently, based on 16S rRNA gene sequence analysis, phylogenetic trees are inferred by the NJ and UPGMA methods. In this second approach, the species classification problem is based on the combination of two different types of data. Herein, 16S rRNA gene sequence data is used for phylogenetic tree inference and the corresponding binary tree splits are learned based on FAME data. We call this learning approach 'phylogenetic learning'. Supervised Random Forest models are developed to train the classification tasks in a stratified cross-validation setting. In this way, better classification results are obtained for species that are typically hard to distinguish by a single or flat multi-class classification model. Conclusions FAME-based bacterial species classification is successfully evaluated in a taxonomic framework. Although the proposed approach does not improve the overall accuracy compared to flat multi-class classification, it has some distinct advantages. First, it has better capabilities for distinguishing species on which flat multi-class classification fails. Secondly, the hierarchical classification structure allows to easily evaluate and visualize the resolution of FAME data for

Genomic analysis reveals the major driving forces of bacterial life in the rhizosphere

PubMed Central

Matilla, Miguel A; Espinosa-Urgel, Manuel; Rodríguez-Herva, José J; Ramos, Juan L; Ramos-González, María Isabel

2007-01-01

Background Mutualistic interactions less well known than those between rhizobia and legumes are commonly found between plants and bacteria, frequently pseudomonads, which colonize roots and adjacent soil areas (the rhizosphere). Results A global analysis of Pseudomonas putida genes expressed during their interaction with maize roots revealed how a bacterial population adjusts its genetic program to this lifestyle. Differentially expressed genes were identified by comparing rhizosphere-colonizing populations with three distinct controls covering a variety of nutrients, growth phases and life styles (planktonic and sessile). Ninety rhizosphere up-regulated (rup) genes, which were induced relative to all three controls, were identified, whereas there was no repressed gene in common between the experiments. Genes involved in amino acid uptake and metabolism of aromatic compounds were preferentially expressed in the rhizosphere, which reflects the availability of particular nutrients in root exudates. The induction of efflux pumps and enzymes for glutathione metabolism indicates that adaptation to adverse conditions and stress (oxidative) response are crucial for bacterial life in this environment. The finding of a GGDEF/EAL domain response regulator among the induced genes suggests a role for the turnover of the secondary messenger c-diGMP in root colonization. Several mutants in rup genes showed reduced fitness in competitive root colonization. Conclusion Our results show the importance of two selective forces of different nature to colonize the rhizosphere: stress adaptation and availability of particular nutrients. We also identify new traits conferring bacterial survival in this niche and open a way to the characterization of specific signalling and regulatory processes governing the plant-Pseudomonas association. PMID:17784941

Comparison of the Rhizosphere Bacterial Communities of Zigongdongdou Soybean and a High-Methionine Transgenic Line of This Cultivar

PubMed Central

Ji, Jun; Wu, Haiying; Meng, Fang; Zhang, Mingrong; Zheng, Xiaobo; Wu, Cunxiang; Zhang, Zhengguang

2014-01-01

Previous studies have shown that methionine from root exudates affects the rhizosphere bacterial population involved in soil nitrogen fixation. A transgenic line of Zigongdongdou soybean cultivar (ZD91) that expresses Arabidopsis cystathionine γ-synthase resulting in an increased methionine production was examined for its influence to the rhizosphere bacterial population. Using 16S rRNA gene-based pyrosequencing analysis of the V4 region and DNA extracted from bacterial consortia collected from the rhizosphere of soybean plants grown in an agricultural field at the pod-setting stage, we characterized the populational structure of the bacterial community involved. In total, 87,267 sequences (approximately 10,908 per sample) were analyzed. We found that Acidobacteria, Proteobacteria, Bacteroidetes, Actinobacteria, Chloroflexi, Planctomycetes, Gemmatimonadetes, Firmicutes, and Verrucomicrobia constitute the dominant taxonomic groups in either the ZD91 transgenic line or parental cultivar ZD, and that there was no statistically significant difference in the rhizosphere bacterial community structure between the two cultivars. PMID:25079947

PRODORIC2: the bacterial gene regulation database in 2018

PubMed Central

Dudek, Christian-Alexander; Hartlich, Juliane; Brötje, David; Jahn, Dieter

2018-01-01

Abstract Bacteria adapt to changes in their environment via differential gene expression mediated by DNA binding transcriptional regulators. The PRODORIC2 database hosts one of the largest collections of DNA binding sites for prokaryotic transcription factors. It is the result of the thoroughly redesigned PRODORIC database. PRODORIC2 is more intuitive and user-friendly. Besides significant technical improvements, the new update offers more than 1000 new transcription factor binding sites and 110 new position weight matrices for genome-wide pattern searches with the Virtual Footprint tool. Moreover, binding sites deduced from high-throughput experiments were included. Data for 6 new bacterial species including bacteria of the Rhodobacteraceae family were added. Finally, a comprehensive collection of sigma- and transcription factor data for the nosocomial pathogen Clostridium difficile is now part of the database. PRODORIC2 is publicly available at http://www.prodoric2.de. PMID:29136200

Effect of copper treatment on the composition and function of the bacterial community in the sponge Haliclona cymaeformis.

PubMed

Tian, Ren-Mao; Wang, Yong; Bougouffa, Salim; Gao, Zhao-Ming; Cai, Lin; Zhang, Wei-Peng; Bajic, Vladimir; Qian, Pei-Yuan

2014-11-04

Marine sponges are the most primitive metazoan and host symbiotic microorganisms. They are crucial components of the marine ecological system and play an essential role in pelagic processes. Copper pollution is currently a widespread problem and poses a threat to marine organisms. Here, we examined the effects of copper treatment on the composition of the sponge-associated bacterial community and the genetic features that facilitate the survival of enriched bacteria under copper stress. The 16S rRNA gene sequencing results showed that the sponge Haliclona cymaeformis harbored symbiotic sulfur-oxidizing Ectothiorhodospiraceae and photosynthetic Cyanobacteria as dominant species. However, these autotrophic bacteria decreased substantially after treatment with a high copper concentration, which enriched for a heterotrophic-bacterium-dominated community. Metagenomic comparison revealed a varied profile of functional genes and enriched functions, including bacterial motility and chemotaxis, extracellular polysaccharide and capsule synthesis, virulence-associated genes, and genes involved in cell signaling and regulation, suggesting short-period mechanisms of the enriched bacterial community for surviving copper stress in the microenvironment of the sponge. Microscopic observation and comparison revealed dynamic bacterial aggregation within the matrix and lysis of sponge cells. The bacteriophage community was also enriched, and the complete genome of a dominant phage was determined, implying that a lytic phage cycle was stimulated by the high copper concentration. This study demonstrated a copper-induced shift in the composition of functional genes of the sponge-associated bacterial community, revealing the selective effect of copper treatment on the functions of the bacterial community in the microenvironment of the sponge. This study determined the bacterial community structure of the common sponge Haliclona cymaeformis and examined the effect of copper treatment on

Genes involved in long-chain alkene biosynthesis in Micrococcus luteus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beller, Harry R.; Goh, Ee-Been; Keasling, Jay D.

2010-01-07

Aliphatic hydrocarbons are highly appealing targets for advanced cellulosic biofuels, as they are already predominant components of petroleum-based gasoline and diesel fuels. We have studied alkene biosynthesis in Micrococcus luteus ATCC 4698, a close relative of Sarcina lutea (now Kocuria rhizophila), which four decades ago was reported to biosynthesize iso- and anteiso branched, long-chain alkenes. The underlying biochemistry and genetics of alkene biosynthesis were not elucidated in those studies. We show here that heterologous expression of a three-gene cluster from M. luteus (Mlut_13230-13250) in a fatty-acid overproducing E. coli strain resulted in production of long-chain alkenes, predominantly 27:3 and 29:3more » (no. carbon atoms: no. C=C bonds). Heterologous expression of Mlut_13230 (oleA) alone produced no long-chain alkenes but unsaturated aliphatic monoketones, predominantly 27:2, and in vitro studies with the purified Mlut_13230 protein and tetradecanoyl-CoA produced the same C27 monoketone. Gas chromatography-time of flight mass spectrometry confirmed the elemental composition of all detected long-chain alkenes and monoketones (putative intermediates of alkene biosynthesis). Negative controls demonstrated that the M. luteus genes were responsible for production of these metabolites. Studies with wild-type M. luteus showed that the transcript copy number of Mlut_13230-13250 and the concentrations of 29:1 alkene isomers (the dominant alkenes produced by this strain) generally corresponded with bacterial population over time. We propose a metabolic pathway for alkene biosynthesis starting with acyl-CoA (or -ACP) thioesters and involving decarboxylative Claisen condensation as a key step, which we believe is catalyzed by OleA. Such activity is consistent with our data and with the homology (including the conserved Cys-His-Asn catalytic triad) of Mlut_13230 (OleA) to FabH (?-ketoacyl-ACP synthase III), which catalyzes decarboxylative Claisen

Genes involved in long-chain alkene biosynthesis in Micrococcus luteus.

PubMed

Beller, Harry R; Goh, Ee-Been; Keasling, Jay D

2010-02-01

Aliphatic hydrocarbons are highly appealing targets for advanced cellulosic biofuels, as they are already predominant components of petroleum-based gasoline and diesel fuels. We have studied alkene biosynthesis in Micrococcus luteus ATCC 4698, a close relative of Sarcina lutea (now Kocuria rhizophila), which 4 decades ago was reported to biosynthesize iso- and anteiso-branched, long-chain alkenes. The underlying biochemistry and genetics of alkene biosynthesis were not elucidated in those studies. We show here that heterologous expression of a three-gene cluster from M. luteus (Mlut_13230-13250) in a fatty acid-overproducing Escherichia coli strain resulted in production of long-chain alkenes, predominantly 27:3 and 29:3 (no. carbon atoms: no. C=C bonds). Heterologous expression of Mlut_13230 (oleA) alone produced no long-chain alkenes but unsaturated aliphatic monoketones, predominantly 27:2, and in vitro studies with the purified Mlut_13230 protein and tetradecanoyl-coenzyme A (CoA) produced the same C(27) monoketone. Gas chromatography-time of flight mass spectrometry confirmed the elemental composition of all detected long-chain alkenes and monoketones (putative intermediates of alkene biosynthesis). Negative controls demonstrated that the M. luteus genes were responsible for production of these metabolites. Studies with wild-type M. luteus showed that the transcript copy number of Mlut_13230-13250 and the concentrations of 29:1 alkene isomers (the dominant alkenes produced by this strain) generally corresponded with bacterial population over time. We propose a metabolic pathway for alkene biosynthesis starting with acyl-CoA (or-ACP [acyl carrier protein]) thioesters and involving decarboxylative Claisen condensation as a key step, which we believe is catalyzed by OleA. Such activity is consistent with our data and with the homology (including the conserved Cys-His-Asn catalytic triad) of Mlut_13230 (OleA) to FabH (beta-ketoacyl-ACP synthase III), which

Association between Toll-like receptor 9 gene polymorphisms and risk of bacterial meningitis in a Chinese population.

PubMed

Wang, X H; Shi, H P; Li, F J

2016-07-25

We determined whether two common single nucleotide polymorphisms (SNPs) in the Toll-like receptor 9 gene (TLR9) (TLR9+2848 rs352140 and TLR9-1237 rs5743836) influenced susceptibility to bacterial meningitis in a Chinese population. The study comprised 126 patients with bacterial meningitis and 252 control subjects, all of whom were recruited from the Tuberculosis Hospital of Shanxi Province. Genotyping of TLR9+2848 rs352140 and TLR9-1237 rs5743836 was performed by polymerase chain reaction coupled with restriction fragment length polymorphism. Using logistic regression analysis, we found that individuals with the AA genotype were associated with an increased risk of bacterial meningitis compared with those with the GG genotype (OR = 0.43, 95%CI = 0.19-0.95; P = 0.03). In a recessive model, the AA genotype was correlated with an elevated risk of bacterial meningitis compared with the GG+GA genotype (OR = 0.49, 95%CI = 0.22-0.99; P = 0.04). However, no significant differences were observed in the association between the TLR9-1237 rs5743836 polymorphism and the risk of bacterial meningitis in the codominant, dominant, or recessive models. In conclusion, the results of our study suggest an association between the TLR9+2848 polymorphism and a reduced risk of bacterial meningitis in the codominant and recessive models.

Yeast Kluyveromyces lactis as host for expression of the bacterial lipase: cloning and adaptation of the new lipase gene from Serratia sp.

PubMed

Šiekštelė, Rimantas; Veteikytė, Aušra; Tvaska, Bronius; Matijošytė, Inga

2015-10-01

Many microbial lipases have been successfully expressed in yeasts, but not in industrially attractive Kluyveromyces lactis, which among other benefits can be cultivated on a medium supplemented with whey--cheap and easily available industrial waste. A new bacterial lipase from Serratia sp. was isolated and for the first time expressed into the yeast Kluyveromyces lactis by heterologous protein expression system based on a strong promoter of Kluyveromyces marxianus triosephosphate isomerase gene and signal peptide of Kluyveromyces marxianus endopolygalacturonase gene. In addition, the bacterial lipase gene was synthesized de novo by taking into account a codon usage bias optimal for K. lactis and was expressed into the yeast K. lactis also. Both resulting strains were characterized by high output level of the target protein secreted extracellularly. Secreted lipases were characterized for activity and stability.

Comprehensive phylogenetic analysis of bacterial reverse transcriptases.

PubMed

Toro, Nicolás; Nisa-Martínez, Rafael

2014-01-01

Much less is known about reverse transcriptases (RTs) in prokaryotes than in eukaryotes, with most prokaryotic enzymes still uncharacterized. Two surveys involving BLAST searches for RT genes in prokaryotic genomes revealed the presence of large numbers of diverse, uncharacterized RTs and RT-like sequences. Here, using consistent annotation across all sequenced bacterial species from GenBank and other sources via RAST, available from the PATRIC (Pathogenic Resource Integration Center) platform, we have compiled the data for currently annotated reverse transcriptases from completely sequenced bacterial genomes. RT sequences are broadly distributed across bacterial phyla, but green sulfur bacteria and cyanobacteria have the highest levels of RT sequence diversity (≤85% identity) per genome. By contrast, phylum Actinobacteria, for which a large number of genomes have been sequenced, was found to have a low RT sequence diversity. Phylogenetic analyses revealed that bacterial RTs could be classified into 17 main groups: group II introns, retrons/retron-like RTs, diversity-generating retroelements (DGRs), Abi-like RTs, CRISPR-Cas-associated RTs, group II-like RTs (G2L), and 11 other groups of RTs of unknown function. Proteobacteria had the highest potential functional diversity, as they possessed most of the RT groups. Group II introns and DGRs were the most widely distributed RTs in bacterial phyla. Our results provide insights into bacterial RT phylogeny and the basis for an update of annotation systems based on sequence/domain homology.

Comprehensive Phylogenetic Analysis of Bacterial Reverse Transcriptases

PubMed Central

Toro, Nicolás; Nisa-Martínez, Rafael

2014-01-01

Much less is known about reverse transcriptases (RTs) in prokaryotes than in eukaryotes, with most prokaryotic enzymes still uncharacterized. Two surveys involving BLAST searches for RT genes in prokaryotic genomes revealed the presence of large numbers of diverse, uncharacterized RTs and RT-like sequences. Here, using consistent annotation across all sequenced bacterial species from GenBank and other sources via RAST, available from the PATRIC (Pathogenic Resource Integration Center) platform, we have compiled the data for currently annotated reverse transcriptases from completely sequenced bacterial genomes. RT sequences are broadly distributed across bacterial phyla, but green sulfur bacteria and cyanobacteria have the highest levels of RT sequence diversity (≤85% identity) per genome. By contrast, phylum Actinobacteria, for which a large number of genomes have been sequenced, was found to have a low RT sequence diversity. Phylogenetic analyses revealed that bacterial RTs could be classified into 17 main groups: group II introns, retrons/retron-like RTs, diversity-generating retroelements (DGRs), Abi-like RTs, CRISPR-Cas-associated RTs, group II-like RTs (G2L), and 11 other groups of RTs of unknown function. Proteobacteria had the highest potential functional diversity, as they possessed most of the RT groups. Group II introns and DGRs were the most widely distributed RTs in bacterial phyla. Our results provide insights into bacterial RT phylogeny and the basis for an update of annotation systems based on sequence/domain homology. PMID:25423096

Mining virulence genes using metagenomics.

PubMed

Belda-Ferre, Pedro; Cabrera-Rubio, Raúl; Moya, Andrés; Mira, Alex

2011-01-01

When a bacterial genome is compared to the metagenome of an environment it inhabits, most genes recruit at high sequence identity. In free-living bacteria (for instance marine bacteria compared against the ocean metagenome) certain genomic regions are totally absent in recruitment plots, representing therefore genes unique to individual bacterial isolates. We show that these Metagenomic Islands (MIs) are also visible in bacteria living in human hosts when their genomes are compared to sequences from the human microbiome, despite the compartmentalized structure of human-related environments such as the gut. From an applied point of view, MIs of human pathogens (e.g. those identified in enterohaemorragic Escherichia coli against the gut metagenome or in pathogenic Neisseria meningitidis against the oral metagenome) include virulence genes that appear to be absent in related strains or species present in the microbiome of healthy individuals. We propose that this strategy (i.e. recruitment analysis of pathogenic bacteria against the metagenome of healthy subjects) can be used to detect pathogenicity regions in species where the genes involved in virulence are poorly characterized. Using this approach, we detect well-known pathogenicity islands and identify new potential virulence genes in several human pathogens.

Genomic imbalances in esophageal carcinoma cell lines involve Wnt pathway genes.

PubMed

Brown, Jacqueline; Bothma, Hannelie; Veale, Robin; Willem, Pascale

2011-06-28

To identify molecular markers shared across South African esophageal squamous cell carcinoma (ESCC) cell lines using cytogenetics, fluorescence in situ hybridization (FISH) and single nucleotide polymorphism (SNP) array copy number analysis. We used conventional cytogenetics, FISH, and multicolor FISH to characterize the chromosomal rearrangements of five ESCC cell lines established in South Africa. The whole genome copy number profile was established from 250K SNP arrays, and data was analyzed with the CNAT 4.0 and GISTIC software. We detected common translocation breakpoints involving chromosomes 1p11-12 and 3p11.2, the latter correlated with the deletion, or interruption of the EPHA3 gene. The most significant amplifications involved the following chromosomal regions and genes: 11q13.3 (CCND1, FGF3, FGF4, FGF19, MYEOV), 8q24.21(C-MYC, FAM84B), 11q22.1-q22.3 (BIRC2, BIRC3), 5p15.2 (CTNND2), 3q11.2-q12.2 (MINA) and 18p11.32 (TYMS, YES1). The significant deletions included 1p31.2-p31.1 (CTH, GADD45α, DIRAS3), 2q22.1 (LRP1B), 3p12.1-p14.2 (FHIT), 4q22.1-q32.1 (CASP6, SMAD1), 8p23.2-q11.1 (BNIP3L) and 18q21.1-q21.2 (SMAD4, DCC). The 3p11.2 translocation breakpoint was shared across four cell lines, supporting a role for genes involved at this site, in particular, the EPHA3 gene which has previously been reported to be deleted in ESCC. The finding that a significant number of genes that were amplified (FGF3, FGF4, FGF19, CCND1 and C-MYC) or deleted (SFRP2 gene) are involved in the Wnt and fibroblast growth factor signaling pathways, suggests that these pathways may be activated in these cell lines.

Genomic imbalances in esophageal carcinoma cell lines involve Wnt pathway genes

PubMed Central

Brown, Jacqueline; Bothma, Hannelie; Veale, Robin; Willem, Pascale

2011-01-01

AIM: To identify molecular markers shared across South African esophageal squamous cell carcinoma (ESCC) cell lines using cytogenetics, fluorescence in situ hybridization (FISH) and single nucleotide polymorphism (SNP) array copy number analysis. METHODS: We used conventional cytogenetics, FISH, and multicolor FISH to characterize the chromosomal rearrangements of five ESCC cell lines established in South Africa. The whole genome copy number profile was established from 250K SNP arrays, and data was analyzed with the CNAT 4.0 and GISTIC software. RESULTS: We detected common translocation breakpoints involving chromosomes 1p11-12 and 3p11.2, the latter correlated with the deletion, or interruption of the EPHA3 gene. The most significant amplifications involved the following chromosomal regions and genes: 11q13.3 (CCND1, FGF3, FGF4, FGF19, MYEOV), 8q24.21(C-MYC, FAM84B), 11q22.1-q22.3 (BIRC2, BIRC3), 5p15.2 (CTNND2), 3q11.2-q12.2 (MINA) and 18p11.32 (TYMS, YES1). The significant deletions included 1p31.2-p31.1 (CTH, GADD45α, DIRAS3), 2q22.1 (LRP1B), 3p12.1-p14.2 (FHIT), 4q22.1-q32.1 (CASP6, SMAD1), 8p23.2-q11.1 (BNIP3L) and 18q21.1-q21.2 (SMAD4, DCC). The 3p11.2 translocation breakpoint was shared across four cell lines, supporting a role for genes involved at this site, in particular, the EPHA3 gene which has previously been reported to be deleted in ESCC. CONCLUSION: The finding that a significant number of genes that were amplified (FGF3, FGF4, FGF19, CCND1 and C-MYC) or deleted (SFRP2 gene) are involved in the Wnt and fibroblast growth factor signaling pathways, suggests that these pathways may be activated in these cell lines. PMID:21734802

Refined identification of Vibrio bacterial flora from Acanthasther planci based on biochemical profiling and analysis of housekeeping genes.

PubMed

Rivera-Posada, J A; Pratchett, M; Cano-Gomez, A; Arango-Gomez, J D; Owens, L

2011-09-09

We used a polyphasic approach for precise identification of bacterial flora (Vibrionaceae) isolated from crown-of-thorns starfish (COTS) from Lizard Island (Great Barrier Reef, Australia) and Guam (U.S.A., Western Pacific Ocean). Previous 16S rRNA gene phylogenetic analysis was useful to allocate and identify isolates within the Photobacterium, Splendidus and Harveyi clades but failed in the identification of Vibrio harveyi-like isolates. Species of the V harveyi group have almost indistinguishable phenotypes and genotypes, and thus, identification by standard biochemical tests and 16S rRNA gene analysis is commonly inaccurate. Biochemical profiling and sequence analysis of additional topA and mreB housekeeping genes were carried out for definitive identification of 19 bacterial isolates recovered from sick and wild COTS. For 8 isolates, biochemical profiles and topA and mreB gene sequence alignments with the closest relatives (GenBank) confirmed previous 16S rRNA-based identification: V. fortis and Photobacterium eurosenbergii species (from wild COTS), and V natriegens (from diseased COTS). Further phylogenetic analysis based on topA and mreB concatenated sequences served to identify the remaining 11 V harveyi-like isolates: V. owensii and V. rotiferianus (from wild COTS), and V. owensii, V. rotiferianus, and V. harveyi (from diseased COTS). This study further confirms the reliability of topA-mreB gene sequence analysis for identification of these close species, and it reveals a wider distribution range of the potentially pathogenic V. harveyi group.

A database of human genes and a gene network involved in response to tick-borne encephalitis virus infection.

PubMed

Ignatieva, Elena V; Igoshin, Alexander V; Yudin, Nikolay S

2017-12-28

Tick-borne encephalitis is caused by the neurotropic, positive-sense RNA virus, tick-borne encephalitis virus (TBEV). TBEV infection can lead to a variety of clinical manifestations ranging from slight fever to severe neurological illness. Very little is known about genetic factors predisposing to severe forms of disease caused by TBEV. The aims of the study were to compile a catalog of human genes involved in response to TBEV infection and to rank genes from the catalog based on the number of neighbors in the network of pairwise interactions involving these genes and TBEV RNA or proteins. Based on manual review and curation of scientific publications a catalog comprising 140 human genes involved in response to TBEV infection was developed. To provide access to data on all genes, the TBEVhostDB web resource ( http://icg.nsc.ru/TBEVHostDB/ ) was created. We reconstructed a network formed by pairwise interactions between TBEV virion itself, viral RNA and viral proteins and 140 genes/proteins from TBEVHostDB. Genes were ranked according to the number of interactions in the network. Two genes/proteins (CCR5 and IFNAR1) that had maximal number of interactions were revealed. It was found that the subnetworks formed by CCR5 and IFNAR1 and their neighbors were a fragments of two key pathways functioning during the course of tick-borne encephalitis: (1) the attenuation of interferon-I signaling pathway by the TBEV NS5 protein that targeted peptidase D; (2) proinflammation and tissue damage pathway triggered by chemokine receptor CCR5 interacting with CD4, CCL3, CCL4, CCL2. Among nine genes associated with severe forms of TBEV infection, three genes/proteins (CCR5, IL10, ARID1B) were found to have protein-protein interactions within the network, and two genes/proteins (IFNL3 and the IL10, that was just mentioned) were up- or down-regulated in response to TBEV infection. Based on this finding, potential mechanisms for participation of CCR5, IL10, ARID1B, and IFNL3 in the host

A bacterial-type ABC transporter is involved in aluminum tolerance in rice.

PubMed

Huang, Chao Feng; Yamaji, Naoki; Mitani, Namiki; Yano, Masahiro; Nagamura, Yoshiaki; Ma, Jian Feng

2009-02-01

Aluminum (Al) toxicity is a major factor limiting crop production in acidic soil, but the molecular mechanisms of Al tolerance are poorly understood. Here, we report that two genes, STAR1 (for sensitive to Al rhizotoxicity1) and STAR2, are responsible for Al tolerance in rice. STAR1 encodes a nucleotide binding domain, while STAR2 encodes a transmembrane domain, of a bacterial-type ATP binding cassette (ABC) transporter. Disruption of either gene resulted in hypersensitivity to aluminum toxicity. Both STAR1 and STAR2 are expressed mainly in the roots and are specifically induced by Al exposure. Expression in onion epidermal cells, rice protoplasts, and yeast showed that STAR1 interacts with STAR2 to form a complex that localizes to the vesicle membranes of all root cells, except for those in the epidermal layer of the mature zone. When expressed together in Xenopus laevis oocytes, STAR1/2 shows efflux transport activity specific for UDP-glucose. Furthermore, addition of exogenous UDP-glucose rescued root growth in the star1 mutant exposed to Al. These results indicate that STAR1 and STAR2 form a complex that functions as an ABC transporter, which is required for detoxification of Al in rice. The ABC transporter transports UDP-glucose, which may be used to modify the cell wall.

Prevalence of Antibiotic Resistance Genes and Bacterial Community Composition in a River Influenced by a Wastewater Treatment Plant

PubMed Central

Marti, Elisabet; Jofre, Juan; Balcazar, Jose Luis

2013-01-01

Antibiotic resistance represents a global health problem, requiring better understanding of the ecology of antibiotic resistance genes (ARGs), their selection and their spread in the environment. Antibiotics are constantly released to the environment through wastewater treatment plant (WWTP) effluents. We investigated, therefore, the effect of these discharges on the prevalence of ARGs and bacterial community composition in biofilm and sediment samples of a receiving river. We used culture-independent approaches such as quantitative PCR to determine the prevalence of eleven ARGs and 16S rRNA gene-based pyrosequencing to examine the composition of bacterial communities. Concentration of antibiotics in WWTP influent and effluent were also determined. ARGs such as qnrS, bla TEM, bla CTX-M, bla SHV, erm(B), sul(I), sul(II), tet(O) and tet(W) were detected in all biofilm and sediment samples analyzed. Moreover, we observed a significant increase in the relative abundance of ARGs in biofilm samples collected downstream of the WWTP discharge. We also found significant differences with respect to community structure and composition between upstream and downstream samples. Therefore, our results indicate that WWTP discharges may contribute to the spread of ARGs into the environment and may also impact on the bacterial communities of the receiving river. PMID:24205347

Fate of tetracycline, sulfonamide and fluoroquinolone resistance genes and the changes in bacterial diversity during composting of swine manure.

PubMed

Selvam, Ammaiyappan; Xu, Delin; Zhao, Zhenyong; Wong, Jonathan W C

2012-12-01

This study monitored the abundance of antibiotic resistant genes (ARGs) and the bacterial diversity during composting of swine manure spiked with chlortetracycline, sulfadiazine and ciprofloxacin at two different levels and a control without antibiotics. Resistance genes of tetracycline (tetQ, tetW, tetC, tetG, tetZ and tetY), sulfonamide (sul1, sul2, dfrA1 and dfrA7) and fluoroquinolone (gyrA and parC) represented 0.02-1.91%, 0.67-10.28% and 0.00005-0.0002%, respectively, of the total 16S rDNA copies in the initial composting mass. After 28-42 days of composting, these ARGs, except parC, were undetectable in the composting mass indicating that composting is a potential method of manure management. Polymerase chain reaction-denaturing gradient gel electrophoresis analysis of bacterial 16S rDNA of the composting mass indicated that the addition of antibiotics up to 100, 20 and 20mg/kg of chlortetracycline, sulfadiazine and ciprofloxacin, respectively, elicited only a transient perturbation and the bacterial diversity was restored in due course of composting. Copyright © 2012 Elsevier Ltd. All rights reserved.

Transgenic plants producing the bacterial pheromone N-acyl-homoserine lactone exhibit enhanced resistance to the bacterial phytopathogen Erwinia carotovora.

PubMed

Mäe, A; Montesano, M; Koiv, V; Palva, E T

2001-09-01

Bacterial pheromones, mainly different homoserine lactones, are central to a number of bacterial signaling processes, including those involved in plant pathogenicity. We previously demonstrated that N-oxoacyl-homoserine lactone (OHL) is essential for quorum sensing in the soft-rot phytopathogen Erwinia carotovora. In this pathogen, OHL controls the coordinate activation of genes encoding the main virulence determinants, extracellular plant cell wall degrading enzymes (PCWDEs), in a cell density-dependent manner. We suggest that E. carotovora employ quorum sensing to avoid the premature production of PCWDEs and subsequent activation of plant defense responses. To test whether modulating this sensory system would affect the outcome of a plant-pathogen interaction, we generated transgenic tobacco, producing OHL. This was accomplished by ectopic expression in tobacco of the E. carotovora gene expI, which is responsible for OHL biosynthesis. We show that expI-positive transgenic tobacco lines produced the active pheromone and partially complemented the avirulent phenotype of expI mutants. The OHL-producing tobacco lines exhibited enhanced resistance to infection by wild-type E. carotovora. The results were confirmed by exogenous addition of OHL to wild-type plants, which also resulted in increased resistance to E. carotovora.

Composition and Metabolic Activities of the Bacterial Community in Shrimp Sauce at the Flavor-Forming Stage of Fermentation As Revealed by Metatranscriptome and 16S rRNA Gene Sequencings.

PubMed

Duan, Shan; Hu, Xiaoxi; Li, Mengru; Miao, Jianyin; Du, Jinghe; Wu, Rongli

2016-03-30

The bacterial community and the metabolic activities involved at the flavor-forming stage during the fermentation of shrimp sauce were investigated using metatranscriptome and 16S rRNA gene sequencings. Results showed that the abundance of Tetragenococcus was 95.1%. Tetragenococcus halophilus was identified in 520 of 588 transcripts annotated in the Nr database. Activation of the citrate cycle and oxidative phosphorylation, along with the absence of lactate dehydrogenase gene expression, in T. halophilus suggests that T. halophilus probably underwent aerobic metabolism during shrimp sauce fermentation. The metabolism of amino acids, production of peptidase, and degradation of limonene and pinene were very active in T. halophilus. Carnobacterium, Pseudomonas, Escherichia, Staphylococcus, Bacillus, and Clostridium were also metabolically active, although present in very small populations. Enterococcus, Abiotrophia, Streptococcus, and Lactobacillus were detected in metatranscriptome sequencing, but not in 16S rRNA gene sequencing. Many minor taxa showed no gene expression, suggesting that they were in dormant status.

Involvement of Pacific oyster CgPGRP-S1S in bacterial recognition, agglutination and granulocyte degranulation.

PubMed

Iizuka, Masao; Nagasaki, Toshihiro; Takahashi, Keisuke G; Osada, Makoto; Itoh, Naoki

2014-03-01

Peptidoglycan recognition protein (PGRP) recognizes invading bacteria through their peptidoglycans (PGN), a component of the bacterial cell wall. Insect PGRPs contribute to effective immune systems as inducers of other host defense responses, while this function has not been reported from PGRP of bivalves. In this study, recombinant CgPGRP-S1S (rCgPGRP-S1S), produced in the mantle and the gill, was synthesized and used to elucidate the immunological function of CgPGRP-S1S. rCgPGRP-S1S bound specifically to DAP-type PGN and to Escherichia coli cells, but not to other DAP-type PGN-containing bacterial species, Vibrio anguillarum, or Bacillus subtilis. Antibacterial activity was not detected, but E. coli cells were agglutinated. Moreover, in addition to these direct interactions with bacterial cells, rCgPGRP-S1S induced secretion of granular contents by hemocyte degranulation. Taken together, these results suggest for the first time that a PGRP of bivalves is, just as in insects, involved in host defense, not only by direct interaction with bacteria, but also by triggering other defense pathways. Copyright © 2013 Elsevier Ltd. All rights reserved.

Impact of bacterial biocontrol agents on aflatoxin biosynthetic genes, aflD and aflR expression, and phenotypic aflatoxin B₁ production by Aspergillus flavus under different environmental and nutritional regimes.

PubMed

Al-Saad, Labeed A; Al-Badran, Adnan I; Al-Jumayli, Sami A; Magan, Naresh; Rodríguez, Alicia

2016-01-18

The objectives of this study were to examine the efficacy of four bacterial antagonists against Aspergillus flavus using 50:50 ratio of bacterial cells/conidia for the control of aflatoxin B1 (AFB1) production on two different nutritional matrices, nutrient and maize-based media at different water availabilities (0.98, 0.94 water activity (aw) on nutrient medium; 0.995, 0.98 aw on maize meal agar medium) at 35°C. The indicators of efficacy used were the relative expression of one structural and regulatory gene in the biosynthetic pathway (aflD and aflR respectively) and the production of AFB1. These studies showed that some of the bacterial species could significantly inhibit the relative expression of the aflD and aflR genes at both 0.98 and 0.94 aw on nutrient agar. On maize-based media some of the bacterial antagonists reduced the activity of both genes at 0.94 aw and some at 0.995 aw. However, the results for AFB1 production were not consistent with the effects on gene expression. Some bacterial species stimulated AFB1 production on both nutrient and maize-based media regardless of aw. However, some bacterial treatments did inhibit AFB1 production significantly when compared to the control. Overall, this study suggests that temporal studies are required on the biosynthetic genes under different environmental and nutritional conditions to evaluate the potential of antagonists to control AFB1. Copyright © 2015 Elsevier B.V. All rights reserved.

The diversity and abundance of phytase genes (β-propeller phytases) in bacterial communities of the maize rhizosphere.

PubMed

Cotta, S R; Cavalcante Franco Dias, A; Seldin, L; Andreote, F D; van Elsas, J D

2016-03-01

The ecology of microbial communities associated with organic phosphorus (P) mineralization in soils is still understudied. Here, we assessed the abundance and diversity of bacteria harbouring genes encoding β-propeller phytases (BPP) in the rhizosphere of traditional and transgenic maize cultivated in two Brazilian soils. We found a soil-dependent effect towards a higher abundance of phytase genes in the rhizosphere, and an absence of any impact of plant genotype. Phylogenetic analyses indicated members of the genera Pseudomonas, Caulobacter, Idiomarina and Maricaulis, close to 'uncultured bacteria', to constitute the dominant bacteria hosting this gene. The results obtained validate a methodology to target bacteria that are involved in the organic P cycle, and depict the responsiveness of such bacteria to the rhizosphere, albeit in dependency of the soil in which maize is cultivated. The data also identified the major bacterial groups that are associated with the organic P mineralization function. Micro-organisms play a key role in nutrient balance in soil ecosystems that are essential to life on the planet. However, some processes such as organic phosphorus mineralization, an important source of phosphorus supply in soil, is poorly studied mainly due the absence of an efficient methodology to assess the phytase-producing micro-organisms. In this study, a method to assess beta-propeller phytase (BPP)-carrying bacteria in soil was validated. This method may contribute to the knowledge of how these micro-organisms behave in the environment and contribute for plant growth promotion. © 2015 The Society for Applied Microbiology.

Fastidian gum: the Xylella fastidiosa exopolysaccharide possibly involved in bacterial pathogenicity.

PubMed

da Silva, F R; Vettore, A L; Kemper, E L; Leite, A; Arruda, P

2001-09-25

The Gram-negative bacterium Xylella fastidiosa was the first plant pathogen to be completely sequenced. This species causes several economically important plant diseases, including citrus variegated chlorosis (CVC). Analysis of the genomic sequence of X. fastidiosa revealed a 12 kb DNA fragment containing an operon closely related to the gum operon of Xanthomonas campestris. The presence of all genes involved in the synthesis of sugar precursors, existence of exopolysaccharide (EPS) production regulators in the genome, and the absence of three of the X. campestris gum genes suggested that X. fastidiosa is able to synthesize an EPS different from that of xanthan gum. This novel EPS probably consists of polymerized tetrasaccharide repeating units assembled by the sequential addition of glucose-1-phosphate, glucose, mannose and glucuronic acid on a polyprenol phosphate carrier.

High-throughput platform for the discovery of elicitors of silent bacterial gene clusters.

PubMed

Seyedsayamdost, Mohammad R

2014-05-20

Over the past decade, bacterial genome sequences have revealed an immense reservoir of biosynthetic gene clusters, sets of contiguous genes that have the potential to produce drugs or drug-like molecules. However, the majority of these gene clusters appear to be inactive for unknown reasons prompting terms such as "cryptic" or "silent" to describe them. Because natural products have been a major source of therapeutic molecules, methods that rationally activate these silent clusters would have a profound impact on drug discovery. Herein, a new strategy is outlined for awakening silent gene clusters using small molecule elicitors. In this method, a genetic reporter construct affords a facile read-out for activation of the silent cluster of interest, while high-throughput screening of small molecule libraries provides potential inducers. This approach was applied to two cryptic gene clusters in the pathogenic model Burkholderia thailandensis. The results not only demonstrate a prominent activation of these two clusters, but also reveal that the majority of elicitors are themselves antibiotics, most in common clinical use. Antibiotics, which kill B. thailandensis at high concentrations, act as inducers of secondary metabolism at low concentrations. One of these antibiotics, trimethoprim, served as a global activator of secondary metabolism by inducing at least five biosynthetic pathways. Further application of this strategy promises to uncover the regulatory networks that activate silent gene clusters while at the same time providing access to the vast array of cryptic molecules found in bacteria.

Recent progresses on AI-2 bacterial quorum sensing inhibitors.

PubMed

Zhu, Peng; Li, Minyong

2012-01-01

Quorum sensing (QS) is a communication procedure that predominates gene expression in response to cell density and fluctuations in the neighboring environment as a result of discerning molecules termed autoinducers (AIs). It has been embroiled that QS can govern bacterial behaviors such as the secretion of virulence factors, biofilm formation, bioluminescence production, conjugation, sporulation and swarming motility. Autoinducer 2 (AI-2), a QS signaling molecule brought up to be involved in interspecies communication, exists in both gram-negative and -positive bacteria. Therefore, novel approaches to interrupt AI-2 quorum sensing are being recognized as next generation antimicrobials. In the present review article, we summarized recent progresses on AI-2 bacterial quorum sensing inhibitors and discussed their potential as the antibacterial agents.

Identification of Three Alcohol Dehydrogenase Genes Involved in the Stereospecific Catabolism of Arylglycerol-β-Aryl Ether by Sphingobium sp. Strain SYK-6▿ †

PubMed Central

Sato, Yusuke; Moriuchi, Hideki; Hishiyama, Shojiro; Otsuka, Yuichiro; Oshima, Kenji; Kasai, Daisuke; Nakamura, Masaya; Ohara, Seiji; Katayama, Yoshihiro; Fukuda, Masao; Masai, Eiji

2009-01-01

Degradation of arylglycerol-β-aryl ether is the most important process in bacterial lignin catabolism. Sphingobium sp. strain SYK-6 degrades guaiacylglycerol-β-guaiacyl ether (GGE) to α-(2-methoxyphenoxy)-β-hydroxypropiovanillone (MPHPV), and then the ether linkage of MPHPV is cleaved to generate α-glutathionyl-β-hydroxypropiovanillone (GS-HPV) and guaiacol. We have characterized three enantioselective glutathione S-transferase genes, including two genes that are involved in the ether cleavage of two enantiomers of MPHPV and one gene that is involved in the elimination of glutathione from a GS-HPV enantiomer. However, the first step in the degradation of four different GGE stereoisomers has not been characterized. In this study, three alcohol dehydrogenase genes, ligL, ligN, and ligO, which conferred GGE transformation activity in Escherichia coli, were isolated from SYK-6 and characterized, in addition to the previously cloned ligD gene. The levels of amino acid sequence identity of the four GGE dehydrogenases, which belong to the short-chain dehydrogenase/reductase family, ranged from 32% to 39%. Each gene was expressed in E. coli, and the stereospecificities of the gene products with the four GGE stereoisomers were determined by using chiral high-performance liquid chromatography with recently synthesized authentic enantiopure GGE stereoisomers. LigD and LigO converted (αR,βS)-GGE and (αR,βR)-GGE into (βS)-MPHPV and (βR)-MPHPV, respectively, while LigL and LigN transformed (αS,βR)-GGE and (αS,βS)-GGE to (βR)-MPHPV and (βS)-MPHPV, respectively. Disruption of the genes indicated that ligD is essential for the degradation of (αR,βS)-GGE and (αR,βR)-GGE and that both ligL and ligN contribute to the degradation of the two other GGE stereoisomers. PMID:19542348

Genomewide screening for genes involved in biofilm formation and miconazole susceptibility in Saccharomyces cerevisiae.

PubMed

Vandenbosch, Davy; De Canck, Evelien; Dhondt, Inne; Rigole, Petra; Nelis, Hans J; Coenye, Tom

2013-12-01

Infections related to fungal biofilms are difficult to treat due to the reduced susceptibility of sessile cells to most antifungal agents. Previous research has shown that 1-10% of sessile Candida cells survive treatment with high doses of miconazole (a fungicidal imidazole). The aim of this study was to identify genes involved in fungal biofilm formation and to unravel the mechanisms of resistance of these biofilms to miconazole. To this end, a screening of a Saccharomyces cerevisiae deletion mutant bank was carried out. Our results revealed that genes involved in peroxisomal transport and the biogenesis of the respiratory chain complex IV play an essential role in biofilm formation. On the other hand, genes involved in transcription and peroxisomal and mitochondrial organization seem to highly influence the susceptibility to miconazole of yeast biofilms. Additionally, our data confirm previous findings on genes involved in biofilm formation and in general stress responses. Our data suggest the involvement of peroxisomes in biofilm formation and miconazole resistance in fungal biofilms. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

The construction of recombinant industrial yeasts free of bacterial sequences by directed gene replacement into a nonessential region of the genome.

PubMed

Xiao, W; Rank, G H

1989-03-15

The yeast SMR1 gene was used as a dominant resistance-selectable marker for industrial yeast transformation and for targeting integration of an economically important gene at the homologous ILV2 locus. A MEL1 gene, which codes for alpha-galactosidase, was inserted into a dispensable upstream region of SMR1 in vitro; different treatments of the plasmid (pWX813) prior to transformation resulted in 3' end, 5' end and replacement integrations that exhibited distinct integrant structures. One-step replacement within a nonessential region of the host genome generated a stable integration of MEL1 devoid of bacterial plasmid DNA. Using this method, we have constructed several alpha-galactosidase positive industrial Saccharomyces strains. Our study provides a general method for stable gene transfer in most industrial Saccharomyces yeasts, including those used in the baking, brewing (ale and lager), distilling, wine and sake industries, with solely nucleotide sequences of interest. The absence of bacterial DNA in the integrant structure facilitates the commercial application of recombinant DNA technology in the food and beverage industry.

Metagenomic analysis of bacterial community composition and antibiotic resistance genes in a wastewater treatment plant and its receiving surface water.

PubMed

Tang, Junying; Bu, Yuanqing; Zhang, Xu-Xiang; Huang, Kailong; He, Xiwei; Ye, Lin; Shan, Zhengjun; Ren, Hongqiang

2016-10-01

The presence of pathogenic bacteria and the dissemination of antibiotic resistance genes (ARGs) may pose big risks to the rivers that receive the effluent from municipal wastewater treatment plants (WWTPs). In this study, we investigated the changes of bacterial community and ARGs along treatment processes of one WWTP, and examined the effects of the effluent discharge on the bacterial community and ARGs in the receiving river. Pyrosequencing was applied to reveal bacterial community composition including potential bacterial pathogen, and Illumina high-throughput sequencing was used for profiling ARGs. The results showed that the WWTP had good removal efficiency on potential pathogenic bacteria (especially Arcobacter butzleri) and ARGs. Moreover, the bacterial communities of downstream and upstream of the river showed no significant difference. However, the increase in the abundance of potential pathogens and ARGs at effluent outfall was observed, indicating that WWTP effluent might contribute to the dissemination of potential pathogenic bacteria and ARGs in the receiving river. Copyright © 2016 Elsevier Inc. All rights reserved.

Characterization of regulatory pathways in Xylella fastidiosa: genes and phenotypes controlled by algU.

PubMed

Shi, Xiang Yang; Dumenyo, C Korsi; Hernandez-Martinez, Rufina; Azad, Hamid; Cooksey, Donald A

2007-11-01

Many virulence genes in plant bacterial pathogens are coordinately regulated by "global" regulatory genes. Conducting DNA microarray analysis of bacterial mutants of such genes, compared with the wild type, can help to refine the list of genes that may contribute to virulence in bacterial pathogens. The regulatory gene algU, with roles in stress response and regulation of the biosynthesis of the exopolysaccharide alginate in Pseudomonas aeruginosa and many other bacteria, has been extensively studied. The role of algU in Xylella fastidiosa, the cause of Pierce's disease of grapevines, was analyzed by mutation and whole-genome microarray analysis to define its involvement in aggregation, biofilm formation, and virulence. In this study, an algU::nptII mutant had reduced cell-cell aggregation, attachment, and biofilm formation and lower virulence in grapevines. Microarray analysis showed that 42 genes had significantly lower expression in the algU::nptII mutant than in the wild type. Among these are several genes that could contribute to cell aggregation and biofilm formation, as well as other physiological processes such as virulence, competition, and survival.

Comprehensive Analysis of Bacterial Flora in Postoperative Maxillary Cyst Fluid by 16S rRNA Gene and Culture Methods

PubMed Central

Sano, Naoto; Yamashita, Yoshio; Fukuda, Kazumasa; Taniguchi, Hatsumi; Goto, Masaaki; Miyamoto, Hiroshi

2012-01-01

Intracystic fluid was aseptically collected from 11 patients with postoperative maxillary cyst (POMC), and DNA was extracted from the POMC fluid. Bacterial species were identified by sequencing after cloning of approximately 580 bp of the 16S rRNA gene. Identification of pathogenic bacteria was also performed by culture methods. The phylogenetic identity was determined by sequencing 517–596 bp in each of the 1139 16S rRNA gene clones. A total of 1114 clones were classified while the remaining 25 clones were unclassified. A total of 103 bacterial species belonging to 42 genera were identified in POMC fluid samples by 16S rRNA gene analysis. Species of Prevotella (91%), Neisseria (73%), Fusobacterium (73%), Porphyromonas (73%), and Propionibacterium (73%) were found to be highly prevalent in all patients. Streptococcus mitis (64%), Fusobacterium nucleatum (55%), Propionibacterium acnes (55%), Staphylococcus capitis (55%), and Streptococcus salivarius (55%) were detected in more than 6 of the 11 patients. The results obtained by the culture method were different from those obtained by 16S rRNA gene analysis, but both approaches may be necessary for the identification of pathogens, especially of bacteria that are difficult to detect by culture methods, and the development of rational treatments for patients with POMC. PMID:22685668

The ECF sigma factor, PSPTO_1043, in Pseudomonas syringae pv. tomato DC3000 is induced by oxidative stress and regulates genes involved in oxidative stress response

PubMed Central

Butcher, Bronwyn G.; Bao, Zhongmeng; Wilson, Janet; Swingle, Bryan; Filiatrault, Melanie; Schneider, David; Cartinhour, Samuel

2017-01-01

The bacterial plant pathogen Pseudomonas syringae adapts to changes in the environment by modifying its gene expression profile. In many cases, the response is mediated by the activation of extracytoplasmic function (ECF) sigma factors that direct RNA polymerase to transcribe specific sets of genes. In this study we focus on PSPTO_1043, one of ten ECF sigma factors in P. syringae pv. tomato DC3000 (DC3000). PSPTO_1043, together with PSPTO_1042, encode an RpoERsp/ChrR-like sigma/anti-sigma factor pair. Although this gene pair is unique to the P. syringae group among the pseudomonads, homologous genes can be found in photosynthetic genera such as Rhodospirillum, Thalassospira, Phaeospirillum and Parvibaculum. Using ChIP-Seq, we detected 137 putative PSPTO_1043 binding sites and identified a likely promoter motif. We characterized 13 promoter candidates, six of which regulate genes that appear to be found only in P. syringae. PSPTO_1043 responds to the presence of singlet oxygen (1O2) and tert-butyl hydroperoxide (tBOOH) and several of the genes regulated by PSPTO_1043 appear to be involved in response to oxidative stress. PMID:28700608

The ECF sigma factor, PSPTO_1043, in Pseudomonas syringae pv. tomato DC3000 is induced by oxidative stress and regulates genes involved in oxidative stress response.

PubMed

Butcher, Bronwyn G; Bao, Zhongmeng; Wilson, Janet; Stodghill, Paul; Swingle, Bryan; Filiatrault, Melanie; Schneider, David; Cartinhour, Samuel

2017-01-01

The bacterial plant pathogen Pseudomonas syringae adapts to changes in the environment by modifying its gene expression profile. In many cases, the response is mediated by the activation of extracytoplasmic function (ECF) sigma factors that direct RNA polymerase to transcribe specific sets of genes. In this study we focus on PSPTO_1043, one of ten ECF sigma factors in P. syringae pv. tomato DC3000 (DC3000). PSPTO_1043, together with PSPTO_1042, encode an RpoERsp/ChrR-like sigma/anti-sigma factor pair. Although this gene pair is unique to the P. syringae group among the pseudomonads, homologous genes can be found in photosynthetic genera such as Rhodospirillum, Thalassospira, Phaeospirillum and Parvibaculum. Using ChIP-Seq, we detected 137 putative PSPTO_1043 binding sites and identified a likely promoter motif. We characterized 13 promoter candidates, six of which regulate genes that appear to be found only in P. syringae. PSPTO_1043 responds to the presence of singlet oxygen (1O2) and tert-butyl hydroperoxide (tBOOH) and several of the genes regulated by PSPTO_1043 appear to be involved in response to oxidative stress.

A cluster of bacterial genes for anaerobic benzene ring biodegradation

PubMed Central

Egland, Paul G.; Pelletier, Dale A.; Dispensa, Marilyn; Gibson, Jane; Harwood, Caroline S.

1997-01-01

A reductive benzoate pathway is the central conduit for the anaerobic biodegradation of aromatic pollutants and lignin monomers. Benzene ring reduction requires a large input of energy and this metabolic capability has, so far, been reported only in bacteria. To determine the molecular basis for this environmentally important process, we cloned and analyzed genes required for the anaerobic degradation of benzoate and related compounds from the phototrophic bacterium, Rhodopseudomonas palustris. A cluster of 24 genes was identified that includes twelve genes likely to be involved in anaerobic benzoate degradation and additional genes that convert the related compounds 4-hydroxybenzoate and cyclohexanecarboxylate to benzoyl-CoA. Genes encoding benzoyl-CoA reductase, a novel enzyme able to overcome the resonance stability of the aromatic ring, were identified by directed mutagenesis. The gene encoding the ring-cleavage enzyme, 2-ketocyclohexanecarboxyl-CoA hydrolase, was identified by assaying the enzymatic activity of the protein expressed in Escherichia coli. Physiological data and DNA sequence analyses indicate that the benzoate pathway consists of unusual enzymes for ring reduction and cleavage interposed among enzymes homologous to those catalyzing fatty acid degradation. The cloned genes should be useful as probes to identify benzoate degradation genes from other metabolically distinct groups of anaerobic bacteria, such as denitrifying bacteria and sulfate-reducing bacteria. PMID:9177244

New genes of Xanthomonas citri subsp. citri involved in pathogenesis and adaptation revealed by a transposon-based mutant library

PubMed Central

2009-01-01

Background Citrus canker is a disease caused by the phytopathogens Xanthomonas citri subsp. citri, Xanthomonas fuscans subsp. aurantifolli and Xanthomonas alfalfae subsp. citrumelonis. The first of the three species, which causes citrus bacterial canker type A, is the most widely spread and severe, attacking all citrus species. In Brazil, this species is the most important, being found in practically all areas where citrus canker has been detected. Like most phytobacterioses, there is no efficient way to control citrus canker. Considering the importance of the disease worldwide, investigation is needed to accurately detect which genes are related to the pathogen-host adaptation process and which are associated with pathogenesis. Results Through transposon insertion mutagenesis, 10,000 mutants of Xanthomonas citri subsp. citri strain 306 (Xcc) were obtained, and 3,300 were inoculated in Rangpur lime (Citrus limonia) leaves. Their ability to cause citrus canker was analyzed every 3 days until 21 days after inoculation; a set of 44 mutants showed altered virulence, with 8 presenting a complete loss of causing citrus canker symptoms. Sequencing of the insertion site in all 44 mutants revealed that 35 different ORFs were hit, since some ORFs were hit in more than one mutant, with mutants for the same ORF presenting the same phenotype. An analysis of these ORFs showed that some encoded genes were previously known as related to pathogenicity in phytobacteria and, more interestingly, revealed new genes never implicated with Xanthomonas pathogenicity before, including hypothetical ORFs. Among the 8 mutants with no canker symptoms are the hrpB4 and hrpX genes, two genes that belong to type III secretion system (TTSS), two hypothetical ORFS and, surprisingly, the htrA gene, a gene reported as involved with the virulence process in animal-pathogenic bacteria but not described as involved in phytobacteria virulence. Nucleic acid hybridization using labeled cDNA probes showed

Examination of Signatures of Recent Positive Selection on Genes Involved in Human Sialic Acid Biology.

PubMed

Moon, Jiyun M; Aronoff, David M; Capra, John A; Abbot, Patrick; Rokas, Antonis

2018-03-28

Sialic acids are nine carbon sugars ubiquitously found on the surfaces of vertebrate cells and are involved in various immune response-related processes. In humans, at least 58 genes spanning diverse functions, from biosynthesis and activation to recycling and degradation, are involved in sialic acid biology. Because of their role in immunity, sialic acid biology genes have been hypothesized to exhibit elevated rates of evolutionary change. Consistent with this hypothesis, several genes involved in sialic acid biology have experienced higher rates of non-synonymous substitutions in the human lineage than their counterparts in other great apes, perhaps in response to ancient pathogens that infected hominins millions of years ago (paleopathogens). To test whether sialic acid biology genes have also experienced more recent positive selection during the evolution of the modern human lineage, reflecting adaptation to contemporary cosmopolitan or geographically-restricted pathogens, we examined whether their protein-coding regions showed evidence of recent hard and soft selective sweeps. This examination involved the calculation of four measures that quantify changes in allele frequency spectra, extent of population differentiation, and haplotype homozygosity caused by recent hard and soft selective sweeps for 55 sialic acid biology genes using publicly available whole genome sequencing data from 1,668 humans from three ethnic groups. To disentangle evidence for selection from confounding demographic effects, we compared the observed patterns in sialic acid biology genes to simulated sequences of the same length under a model of neutral evolution that takes into account human demographic history. We found that the patterns of genetic variation of most sialic acid biology genes did not significantly deviate from neutral expectations and were not significantly different among genes belonging to different functional categories. Those few sialic acid biology genes that

Use of a bacterial expression vector to map the varicella-zoster virus major glycoprotein gene, gC.

PubMed Central

Ellis, R W; Keller, P M; Lowe, R S; Zivin, R A

1985-01-01

The genome of varicella-zoster virus (VZV) encodes at least three major glycoprotein genes. Among viral gene products, the gC gene products are the most abundant glycoproteins and induce a substantial humoral immune response (Keller et al., J. Virol. 52:293-297, 1984). We utilized two independent approaches to map the gC gene. Small fragments of randomly digested VZV DNA were inserted into a bacterial expression vector. Bacterial colonies transformed by this vector library were screened serologically for antigen expression with monoclonal antibodies to gC. Hybridization of the plasmid DNA from a gC antigen-positive clone revealed homology to the 3' end of the VZV Us segment. In addition, mRNA from VZV-infected cells was hybrid selected by a set of VZV DNA recombinant plasmids and translated in vitro, and polypeptide products were immunoprecipitated by convalescent zoster serum or by monoclonal antibodies to gC. This analysis revealed that the mRNA encoding a 70,000-dalton polypeptide precipitable by anti-gC antibodies mapped to the HindIII C fragment, which circumscribes the entire Us region. We conclude that the VZV gC glycoprotein gene maps to the 3' end of the Us region and is expressed as a 70,000-dalton primary translational product. These results are consistent with the recently reported DNA sequence of Us (A.J. Davison, EMBO J. 2:2203-2209, 1983). Furthermore, glycosylation appears not to be required for a predominant portion of the antigenicity of gC glycoproteins. We also report the tentative map assignments for eight other VZV primary translational products. Images PMID:2981365

Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment.

PubMed

Davin-Regli, Anne; Pagès, Jean-Marie

2015-01-01

Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution.

Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment

PubMed Central

Davin-Regli, Anne; Pagès, Jean-Marie

2015-01-01

Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution. PMID:26042091

Identification and characterization of nuclear genes involved in photosynthesis in Populus

PubMed Central

2014-01-01

Background The gap between the real and potential photosynthetic rate under field conditions suggests that photosynthesis could potentially be improved. Nuclear genes provide possible targets for improving photosynthetic efficiency. Hence, genome-wide identification and characterization of the nuclear genes affecting photosynthetic traits in woody plants would provide key insights on genetic regulation of photosynthesis and identify candidate processes for improvement of photosynthesis. Results Using microarray and bulked segregant analysis strategies, we identified differentially expressed nuclear genes for photosynthesis traits in a segregating population of poplar. We identified 515 differentially expressed genes in this population (FC ≥ 2 or FC ≤ 0.5, P < 0.05), 163 up-regulated and 352 down-regulated. Real-time PCR expression analysis confirmed the microarray data. Singular Enrichment Analysis identified 48 significantly enriched GO terms for molecular functions (28), biological processes (18) and cell components (2). Furthermore, we selected six candidate genes for functional examination by a single-marker association approach, which demonstrated that 20 SNPs in five candidate genes significantly associated with photosynthetic traits, and the phenotypic variance explained by each SNP ranged from 2.3% to 12.6%. This revealed that regulation of photosynthesis by the nuclear genome mainly involves transport, metabolism and response to stimulus functions. Conclusions This study provides new genome-scale strategies for the discovery of potential candidate genes affecting photosynthesis in Populus, and for identification of the functions of genes involved in regulation of photosynthesis. This work also suggests that improving photosynthetic efficiency under field conditions will require the consideration of multiple factors, such as stress responses. PMID:24673936

Lag Phase Is a Distinct Growth Phase That Prepares Bacteria for Exponential Growth and Involves Transient Metal Accumulation

PubMed Central

Rolfe, Matthew D.; Rice, Christopher J.; Lucchini, Sacha; Pin, Carmen; Thompson, Arthur; Cameron, Andrew D. S.; Alston, Mark; Stringer, Michael F.; Betts, Roy P.; Baranyi, József; Peck, Michael W.

2012-01-01

Lag phase represents the earliest and most poorly understood stage of the bacterial growth cycle. We developed a reproducible experimental system and conducted functional genomic and physiological analyses of a 2-h lag phase in Salmonella enterica serovar Typhimurium. Adaptation began within 4 min of inoculation into fresh LB medium with the transient expression of genes involved in phosphate uptake. The main lag-phase transcriptional program initiated at 20 min with the upregulation of 945 genes encoding processes such as transcription, translation, iron-sulfur protein assembly, nucleotide metabolism, LPS biosynthesis, and aerobic respiration. ChIP-chip revealed that RNA polymerase was not “poised” upstream of the bacterial genes that are rapidly induced at the beginning of lag phase, suggesting a mechanism that involves de novo partitioning of RNA polymerase to transcribe 522 bacterial genes within 4 min of leaving stationary phase. We used inductively coupled plasma mass spectrometry (ICP-MS) to discover that iron, calcium, and manganese are accumulated by S. Typhimurium during lag phase, while levels of cobalt, nickel, and sodium showed distinct growth-phase-specific patterns. The high concentration of iron during lag phase was associated with transient sensitivity to oxidative stress. The study of lag phase promises to identify the physiological and regulatory processes responsible for adaptation to new environments. PMID:22139505

Procedures involving lipid media for detection of bacterial contamination in breweries.

PubMed

Van Vuuren, H J; Louw, H A; Loos, M A; Meisel, R

1977-02-01

The liquid equivalent of universal beer agar, designated universal beer liquid medium, and its beer-free equivalent, universal liquid medium (UL), were equally effective in demonstrating bacterial contamination in 120 of 200 samples from different stages of commercial brewing process. Growth of the contaminants after 3 days was consistently more luxuriant in the UL medium. A yeast-water substrate medium failed to reveal many contaminants detected with UL in 392 samples from three breweries and revealed only a few not detected with UL. The use of UL and a lactose-peptone medium, with microscope examination of the media for bacterial growth, permitted detection of 93% of the known contaminants compared to 87%, detected with UL alone; this combination or universal beer liquid medium plus lactose-peptone medium can therefore be recommended for the detection of bacterial contaminants in brewery samples. Bacterial contamination of pitching yeasts appeared to be a particular problem in the breweries investigated.

Genome-Wide Association Study Identifies NBS-LRR-Encoding Genes Related with Anthracnose and Common Bacterial Blight in the Common Bean.

PubMed

Wu, Jing; Zhu, Jifeng; Wang, Lanfen; Wang, Shumin

2017-01-01

Nucleotide-binding site and leucine-rich repeat (NBS-LRR) genes represent the largest and most important disease resistance genes in plants. The genome sequence of the common bean ( Phaseolus vulgaris L.) provides valuable data for determining the genomic organization of NBS-LRR genes. However, data on the NBS-LRR genes in the common bean are limited. In total, 178 NBS-LRR-type genes and 145 partial genes (with or without a NBS) located on 11 common bean chromosomes were identified from genome sequences database. Furthermore, 30 NBS-LRR genes were classified into Toll/interleukin-1 receptor (TIR)-NBS-LRR (TNL) types, and 148 NBS-LRR genes were classified into coiled-coil (CC)-NBS-LRR (CNL) types. Moreover, the phylogenetic tree supported the division of these PvNBS genes into two obvious groups, TNL types and CNL types. We also built expression profiles of NBS genes in response to anthracnose and common bacterial blight using qRT-PCR. Finally, we detected nine disease resistance loci for anthracnose (ANT) and seven for common bacterial blight (CBB) using the developed NBS-SSR markers. Among these loci, NSSR24, NSSR73, and NSSR265 may be located at new regions for ANT resistance, while NSSR65 and NSSR260 may be located at new regions for CBB resistance. Furthermore, we validated NSSR24, NSSR65, NSSR73, NSSR260, and NSSR265 using a new natural population. Our results provide useful information regarding the function of the NBS-LRR proteins and will accelerate the functional genomics and evolutionary studies of NBS-LRR genes in food legumes. NBS-SSR markers represent a wide-reaching resource for molecular breeding in the common bean and other food legumes. Collectively, our results should be of broad interest to bean scientists and breeders.

Genome-Wide Association Study Identifies NBS-LRR-Encoding Genes Related with Anthracnose and Common Bacterial Blight in the Common Bean

PubMed Central

Wu, Jing; Zhu, Jifeng; Wang, Lanfen; Wang, Shumin

2017-01-01

Nucleotide-binding site and leucine-rich repeat (NBS-LRR) genes represent the largest and most important disease resistance genes in plants. The genome sequence of the common bean (Phaseolus vulgaris L.) provides valuable data for determining the genomic organization of NBS-LRR genes. However, data on the NBS-LRR genes in the common bean are limited. In total, 178 NBS-LRR-type genes and 145 partial genes (with or without a NBS) located on 11 common bean chromosomes were identified from genome sequences database. Furthermore, 30 NBS-LRR genes were classified into Toll/interleukin-1 receptor (TIR)-NBS-LRR (TNL) types, and 148 NBS-LRR genes were classified into coiled-coil (CC)-NBS-LRR (CNL) types. Moreover, the phylogenetic tree supported the division of these PvNBS genes into two obvious groups, TNL types and CNL types. We also built expression profiles of NBS genes in response to anthracnose and common bacterial blight using qRT-PCR. Finally, we detected nine disease resistance loci for anthracnose (ANT) and seven for common bacterial blight (CBB) using the developed NBS-SSR markers. Among these loci, NSSR24, NSSR73, and NSSR265 may be located at new regions for ANT resistance, while NSSR65 and NSSR260 may be located at new regions for CBB resistance. Furthermore, we validated NSSR24, NSSR65, NSSR73, NSSR260, and NSSR265 using a new natural population. Our results provide useful information regarding the function of the NBS-LRR proteins and will accelerate the functional genomics and evolutionary studies of NBS-LRR genes in food legumes. NBS-SSR markers represent a wide-reaching resource for molecular breeding in the common bean and other food legumes. Collectively, our results should be of broad interest to bean scientists and breeders. PMID:28848595

Influence of different Sinorhizobium meliloti inocula on abundance of genes involved in nitrogen transformations in the rhizosphere of alfalfa (Medicago sativa L.).

PubMed

Babić, Katarina Huić; Schauss, Kristina; Hai, Brigitte; Sikora, Sanja; Redzepović, Sulejman; Radl, Viviane; Schloter, Michael

2008-11-01

Inoculation of leguminous seeds with selected rhizobial strains is practised in agriculture to ameliorate the plant yield by enhanced root nodulation and nitrogen uptake of the plant. However, effective symbiosis between legumes and rhizobia does not only depend on the capacity of nitrogen fixation but also on the entire nitrogen turnover in the rhizosphere. We investigated the influence of seed inoculation with two indigenous Sinorhizobium meliloti strains exhibiting different efficiency concerning plant growth promotion on nitrogen turnover processes in the rhizosphere during the growth of alfalfa. Quantification of six target genes (bacterial amoA, nirK, nirS, nosZ, nifH and archaeal amoA) within the nitrogen cycle was performed in rhizosphere samples before nodule formation, at bud development and at the late flowering stage. The results clearly demonstrated that effectiveness of rhizobial inocula is related to abundance of nifH genes in the late flowering phase of alfalfa. Moreover, other genes involved in nitrogen turnover had been affected by the inocula, e.g. higher numbers of amoA copies were observed during flowering when the more effective strain had been inoculated. However, the respective gene abundances differed overall to a greater extent between the three plant development stages than between the inoculation variants.

Computational design of a Zn2+ receptor that controls bacterial gene expression

NASA Astrophysics Data System (ADS)

Dwyer, M. A.; Looger, L. L.; Hellinga, H. W.

2003-09-01

The control of cellular physiology and gene expression in response to extracellular signals is a basic property of living systems. We have constructed a synthetic bacterial signal transduction pathway in which gene expression is controlled by extracellular Zn2+. In this system a computationally designed Zn2+-binding periplasmic receptor senses the extracellular solute and triggers a two-component signal transduction pathway via a chimeric transmembrane protein, resulting in transcriptional up-regulation of a -galactosidase reporter gene. The Zn2+-binding site in the designed receptor is based on a four-coordinate, tetrahedral primary coordination sphere consisting of histidines and glutamates. In addition, mutations were introduced in a secondary coordination sphere to satisfy the residual hydrogen-bonding potential of the histidines coordinated to the metal. The importance of the secondary shell interactions is demonstrated by their effect on metal affinity and selectivity, as well as protein stability. Three designed protein sequences, comprising two distinct metal-binding positions, were all shown to bind Zn2+ and to function in the cell-based assay, indicating the generality of the design methodology. These experiments demonstrate that biological systems can be manipulated with computationally designed proteins that have drastically altered ligand-binding specificities, thereby extending the repertoire of genetic control by extracellular signals.

Candidate gene markers involved in San Daniele ham quality.

PubMed

Renaville, B; Piasentier, E; Fan, B; Vitale, M; Prandi, A; Rothschild, M F

2010-07-01

San Daniele dry-cured hams (also known as prosciutto) are produced in the Northeastern region of Italy. This high value product requires high quality fresh meat to avoid processing problems. The Sterol Regulatory Element Binding Protein-1 (SREBF1) is a transcription factor involved in the regulation of fatty acid synthesis in muscle and adipose tissues. The SREBF1 gene, its regulating genes SCAP and MBTPS1, and one of its target genes, SCD, were investigated for associations with several meat quality traits of San Daniele hams. Significant associations of some gene markers were found with carcass weight, lean percentage, backfat thickness, ham green weight, ham fat cover thickness, shear force (WBSF), salting losses and instrumental colour of both lean and fat. These findings provide initial evidences that SNPs in SREBF1, SCAP, MBTPS1 and SCD are associated with San Daniele ham quality and may be considered as markers for selective breeding programs. Copyright 2010 Elsevier Ltd. All rights reserved.

The group B streptococcal sialic acid O-acetyltransferase is encoded by neuD, a conserved component of bacterial sialic acid biosynthetic gene clusters.

PubMed

Lewis, Amanda L; Hensler, Mary E; Varki, Ajit; Nizet, Victor

2006-04-21

Nearly two dozen microbial pathogens have surface polysaccharides or lipo-oligosaccharides that contain sialic acid (Sia), and several Sia-dependent virulence mechanisms are known to enhance bacterial survival or result in host tissue injury. Some pathogens are also known to O-acetylate their Sias, although the role of this modification in pathogenesis remains unclear. We report that neuD, a gene located within the Group B Streptococcus (GBS) Sia biosynthetic gene cluster, encodes a Sia O-acetyltransferase that is itself required for capsular polysaccharide (CPS) sialylation. Homology modeling and site-directed mutagenesis identified Lys-123 as a critical residue for Sia O-acetyltransferase activity. Moreover, a single nucleotide polymorphism in neuD can determine whether GBS displays a "high" or "low" Sia O-acetylation phenotype. Complementation analysis revealed that Escherichia coli K1 NeuD also functions as a Sia O-acetyltransferase in GBS. In fact, NeuD homologs are commonly found within Sia biosynthetic gene clusters. A bioinformatic approach identified 18 bacterial species with a Sia biosynthetic gene cluster that included neuD. Included in this list are the sialylated human pathogens Legionella pneumophila, Vibrio parahemeolyticus, Pseudomonas aeruginosa, and Campylobacter jejuni, as well as an additional 12 bacterial species never before analyzed for Sia expression. Phylogenetic analysis shows that NeuD homologs of sialylated pathogens share a common evolutionary lineage distinct from the poly-Sia O-acetyltransferase of E. coli K1. These studies define a molecular genetic approach for the selective elimination of GBS Sia O-acetylation without concurrent loss of sialylation, a key to further studies addressing the role(s) of this modification in bacterial virulence.

Census of solo LuxR genes in prokaryotic genomes

PubMed Central

Hudaiberdiev, Sanjarbek; Choudhary, Kumari S.; Vera Alvarez, Roberto; Gelencsér, Zsolt; Ligeti, Balázs; Lamba, Doriano; Pongor, Sándor

2015-01-01

luxR genes encode transcriptional regulators that control acyl homoserine lactone-based quorum sensing (AHL QS) in Gram negative bacteria. On the bacterial chromosome, luxR genes are usually found next or near to a luxI gene encoding the AHL signal synthase. Recently, a number of luxR genes were described that have no luxI genes in their vicinity on the chromosome. These so-called solo luxR genes may either respond to internal AHL signals produced by a non-adjacent luxI in the chromosome, or can respond to exogenous signals. Here we present a survey of solo luxR genes found in complete and draft bacterial genomes in the NCBI databases using HMMs. We found that 2698 of the 3550 luxR genes found are solos, which is an unexpectedly high number even if some of the hits may be false positives. We also found that solo LuxR sequences form distinct clusters that are different from the clusters of LuxR sequences that are part of the known luxR-luxI topological arrangements. We also found a number of cases that we termed twin luxR topologies, in which two adjacent luxR genes were in tandem or divergent orientation. Many of the luxR solo clusters were devoid of the sequence motifs characteristic of AHL binding LuxR proteins so there is room to speculate that the solos may be involved in sensing hitherto unknown signals. It was noted that only some of the LuxR clades are rich in conserved cysteine residues. Molecular modeling suggests that some of the cysteines may be involved in disulfide formation, which makes us speculate that some LuxR proteins, including some of the solos may be involved in redox regulation. PMID:25815274

Census of solo LuxR genes in prokaryotic genomes.

PubMed

Hudaiberdiev, Sanjarbek; Choudhary, Kumari S; Vera Alvarez, Roberto; Gelencsér, Zsolt; Ligeti, Balázs; Lamba, Doriano; Pongor, Sándor

2015-01-01

luxR genes encode transcriptional regulators that control acyl homoserine lactone-based quorum sensing (AHL QS) in Gram negative bacteria. On the bacterial chromosome, luxR genes are usually found next or near to a luxI gene encoding the AHL signal synthase. Recently, a number of luxR genes were described that have no luxI genes in their vicinity on the chromosome. These so-called solo luxR genes may either respond to internal AHL signals produced by a non-adjacent luxI in the chromosome, or can respond to exogenous signals. Here we present a survey of solo luxR genes found in complete and draft bacterial genomes in the NCBI databases using HMMs. We found that 2698 of the 3550 luxR genes found are solos, which is an unexpectedly high number even if some of the hits may be false positives. We also found that solo LuxR sequences form distinct clusters that are different from the clusters of LuxR sequences that are part of the known luxR-luxI topological arrangements. We also found a number of cases that we termed twin luxR topologies, in which two adjacent luxR genes were in tandem or divergent orientation. Many of the luxR solo clusters were devoid of the sequence motifs characteristic of AHL binding LuxR proteins so there is room to speculate that the solos may be involved in sensing hitherto unknown signals. It was noted that only some of the LuxR clades are rich in conserved cysteine residues. Molecular modeling suggests that some of the cysteines may be involved in disulfide formation, which makes us speculate that some LuxR proteins, including some of the solos may be involved in redox regulation.

Detection of a mixed infection in a culture-negative brain abscess by broad-spectrum bacterial 16S rRNA gene PCR.

PubMed

Keller, Peter M; Rampini, Silvana K; Bloemberg, Guido V

2010-06-01

We describe the identification of two bacterial pathogens from a culture-negative brain abscess by the use of broad-spectrum 16S rRNA gene PCR. Simultaneous detection of Fusobacterium nucleatum and Porphyromonas endodontalis was possible due to a 24-bp length difference of their partially amplified 16S rRNA genes, which allowed separation by high-resolution polyacrylamide gel electrophoresis.

Involvement of Retinoblastoma Protein and HBP1 in Histone H10 Gene Expression

PubMed Central

Lemercier, Claudie; Duncliffe, Kym; Boibessot, Isabelle; Zhang, Hui; Verdel, André; Angelov, Dimitar; Khochbin, Saadi

2000-01-01

The histone H10-encoding gene is expressed in vertebrates in differentiating cells during the arrest of proliferation. In the H10 promoter, a specific regulatory element, which we named the H4 box, exhibits features which implicate a role in mediating H10 gene expression in response to both differentiation and cell cycle control signals. For instance, within the linker histone gene family, the H4 box is found only in the promoters of differentiation-associated subtypes, suggesting that it is specifically involved in differentiation-dependent expression of these genes. In addition, an element nearly identical to the H4 box is conserved in the promoters of histone H4-encoding genes and is known to be involved in their cell cycle-dependent expression. The transcription factors interacting with the H10 H4 box were therefore expected to link differentiation-dependent expression of H10 to the cell cycle control machinery. The aim of this work was to identify such transcription factors and to obtain information concerning the regulatory pathway involved. Interestingly, our cloning strategy led to the isolation of a retinoblastoma protein (RB) partner known as HBP1. HBP1, a high-mobility group box transcription factor, interacted specifically with the H10 H4 box and moreover was expressed in a differentiation-dependent manner. We also showed that the HBP1-encoding gene is able to produce different forms of HBP1. Finally, we demonstrated that both HBP1 and RB were involved in the activation of H10 gene expression. We therefore propose that HBP1 mediates a link between the cell cycle control machinery and cell differentiation signals. Through modulating the expression of specific chromatin-associated proteins such as histone H10, HBP1 plays a vital role in chromatin remodeling events during the arrest of cell proliferation in differentiating cells. PMID:10958660

Identification of bacterial endophytes associated with traditional medicinal plant Tridax procumbens Linn.

PubMed

Preveena, Jagadesan; Bhore, Subhash J

2013-01-01

In traditional medicine, Tridax procumbens Linn. is used in the treatment of injuries and wounds. The bacterial endophytes (BEs) of medicinal plants could produce medicinally important metabolites found in their hosts; and hence, the involvement of BEs in conferring wound healing properties to T. Procumbens cannot be ruled out. But, we do not know which types of BEs are associated with T. Procumbens. The objective of this study was to investigate the fast growing and cultivable BEs associated with T. procumbens. Leaves and stems of healthy T. Procumbens plants were collected and cultivable BEs were isolated from surface-sterilized leaf and stem tissue samples using Luria-Bertani (LB) agar (medium) at standard conditions. A polymerase chain reaction was employed to amplify 16S rRNA coding gene fragments from the isolates. Cultivable endophytic bacterial isolates (EBIs) were identified using 16S rRNA gene nucleotide sequence similarity based method of bacterial identification. Altogether, 50 culturable EBIs were isolated. 16S rRNA gene nucleotide sequences analysis using the Basic Local Alignment Search Tool (BLAST) revealed identities of the EBIs. Analysis reveals that cultivable Bacillus spp., Cronobacter sakazakii, Enterobacter spp., Lysinibacillus sphaericus, Pantoea spp., Pseudomonas spp. and Terribacillus saccharophilus are associated with T. Procumbens. Based on the results, we conclude that 24 different types of culturable BEs are associated with traditionally used medicinal plant, T. Procumbens, and require further study.

Bacterial Outer Membrane Vesicles Induce Plant Immune Responses.

PubMed

Bahar, Ofir; Mordukhovich, Gideon; Luu, Dee Dee; Schwessinger, Benjamin; Daudi, Arsalan; Jehle, Anna Kristina; Felix, Georg; Ronald, Pamela C

2016-05-01

Gram-negative bacteria continuously pinch off portions of their outer membrane, releasing membrane vesicles. These outer membrane vesicles (OMVs) are involved in multiple processes including cell-to-cell communication, biofilm formation, stress tolerance, horizontal gene transfer, and virulence. OMVs are also known modulators of the mammalian immune response. Despite the well-documented role of OMVs in mammalian-bacterial communication, their interaction with plants is not well studied. To examine whether OMVs of plant pathogens modulate the plant immune response, we purified OMVs from four different plant pathogens and used them to treat Arabidopsis thaliana. OMVs rapidly induced a reactive oxygen species burst, medium alkalinization, and defense gene expression in A. thaliana leaf discs, cell cultures, and seedlings, respectively. Western blot analysis revealed that EF-Tu is present in OMVs and that it serves as an elicitor of the plant immune response in this form. Our results further show that the immune coreceptors BAK1 and SOBIR1 mediate OMV perception and response. Taken together, our results demonstrate that plants can detect and respond to OMV-associated molecules by activation of their immune system, revealing a new facet of plant-bacterial interactions.

Screening key candidate genes and pathways involved in insulinoma by microarray analysis.

PubMed

Zhou, Wuhua; Gong, Li; Li, Xuefeng; Wan, Yunyan; Wang, Xiangfei; Li, Huili; Jiang, Bin

2018-06-01

Insulinoma is a rare type tumor and its genetic features remain largely unknown. This study aimed to search for potential key genes and relevant enriched pathways of insulinoma.The gene expression data from GSE73338 were downloaded from Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified between insulinoma tissues and normal pancreas tissues, followed by pathway enrichment analysis, protein-protein interaction (PPI) network construction, and module analysis. The expressions of candidate key genes were validated by quantitative real-time polymerase chain reaction (RT-PCR) in insulinoma tissues.A total of 1632 DEGs were obtained, including 1117 upregulated genes and 514 downregulated genes. Pathway enrichment results showed that upregulated DEGs were significantly implicated in insulin secretion, and downregulated DEGs were mainly enriched in pancreatic secretion. PPI network analysis revealed 7 hub genes with degrees more than 10, including GCG (glucagon), GCGR (glucagon receptor), PLCB1 (phospholipase C, beta 1), CASR (calcium sensing receptor), F2R (coagulation factor II thrombin receptor), GRM1 (glutamate metabotropic receptor 1), and GRM5 (glutamate metabotropic receptor 5). DEGs involved in the significant modules were enriched in calcium signaling pathway, protein ubiquitination, and platelet degranulation. Quantitative RT-PCR data confirmed that the expression trends of these hub genes were similar to the results of bioinformatic analysis.The present study demonstrated that candidate DEGs and enriched pathways were the potential critical molecule events involved in the development of insulinoma, and these findings were useful for better understanding of insulinoma genesis.

Elevated gene expression of S100A12 is correlated with the predominant clinical inflammatory factors in patients with bacterial pneumonia.

PubMed

Hou, Fei; Wang, Likui; Wang, Hong; Gu, Junchao; Li, Meiling; Zhang, Jingkai; Ling, Xiao; Gao, Xiaofang; Luo, Cheng

2015-06-01

Inflammation is the predominant characteristic of pneumonia. The present study aimed to to identify a faster and more reliable novel inflammatory marker for the diagnosis of pneumonia. The expression of the S100A12 gene was analyzed by reverse transcription quantitative polymerase chain reaction in samples obtained from 46 patients with bacterial pneumonia and other infections, compared with samples from 20 healthy individuals, using the 2‑ΔΔCt method. The expression levels of S100A12 were increased in 12 patients with bacterial pneumonia. Compared with clinical inflammatory data, a positive correlation was observed between the expression of the S100A12 gene and levels of white blood cells, C‑reactive protein (CRP), thrombocytocrit, neutrophils, erythrocyte sedimentation and soterocytes, and an inverse correlation was observed with the width of red blood cell volume distribution and platelet distribution, monocytes and hemoglobin, using Pearson's product‑moment correlation method. The P‑value of CRP and erythrocyte sedimentation were revealed to be statistically significant (P<0.05). A sporadic distribution of S100A12 was observed in a heatmap among the patients with different infections and bacterial pneumonia. Furthermore, the expression of S100A12 occurred in parallel to the number of clumps of inflamed tissue observed in chest computed tomography and X‑ray. The value of gene expression of S100A12 (>1.0) determined using the 2‑ΔΔCt method was associated with more severe respiratory diseases in the patients compromised by bacterial pneumonia, sepsis and pancreatitis. These findings suggested that S100A12 is an effective marker for inflammatory diseases.

Bacterial cellulose synthesis mechanism of facultative anaerobe Enterobacter sp. FY-07.

PubMed

Ji, Kaihua; Wang, Wei; Zeng, Bing; Chen, Sibin; Zhao, Qianqian; Chen, Yueqing; Li, Guoqiang; Ma, Ting

2016-02-25

Enterobacter sp. FY-07 can produce bacterial cellulose (BC) under aerobic and anaerobic conditions. Three potential BC synthesis gene clusters (bcsI, bcsII and bcsIII) of Enterobacter sp. FY-07 have been predicted using genome sequencing and comparative genome analysis, in which bcsIII was confirmed as the main contributor to BC synthesis by gene knockout and functional reconstitution methods. Protein homology, gene arrangement and gene constitution analysis indicated that bcsIII had high identity to the bcsI operon of Enterobacter sp. 638; however, its arrangement and composition were same as those of BC synthesizing operon of G. xylinum ATCC53582 except for the flanking sequences. According to the BC biosynthesizing process, oxygen is not directly involved in the reactions of BC synthesis, however, energy is required to activate intermediate metabolites and synthesize the activator, c-di-GMP. Comparative transcriptome and metabolite quantitative analysis demonstrated that under anaerobic conditions genes involved in the TCA cycle were downregulated, however, genes in the nitrate reduction and gluconeogenesis pathways were upregulated, especially, genes in three pyruvate metabolism pathways. These results suggested that Enterobacter sp. FY-07 could produce energy efficiently under anaerobic conditions to meet the requirement of BC biosynthesis.

Bacterial cellulose synthesis mechanism of facultative anaerobe Enterobacter sp. FY-07

PubMed Central

Ji, Kaihua; Wang, Wei; Zeng, Bing; Chen, Sibin; Zhao, Qianqian; Chen, Yueqing; Li, Guoqiang; Ma, Ting

2016-01-01

Enterobacter sp. FY-07 can produce bacterial cellulose (BC) under aerobic and anaerobic conditions. Three potential BC synthesis gene clusters (bcsI, bcsII and bcsIII) of Enterobacter sp. FY-07 have been predicted using genome sequencing and comparative genome analysis, in which bcsIII was confirmed as the main contributor to BC synthesis by gene knockout and functional reconstitution methods. Protein homology, gene arrangement and gene constitution analysis indicated that bcsIII had high identity to the bcsI operon of Enterobacter sp. 638; however, its arrangement and composition were same as those of BC synthesizing operon of G. xylinum ATCC53582 except for the flanking sequences. According to the BC biosynthesizing process, oxygen is not directly involved in the reactions of BC synthesis, however, energy is required to activate intermediate metabolites and synthesize the activator, c-di-GMP. Comparative transcriptome and metabolite quantitative analysis demonstrated that under anaerobic conditions genes involved in the TCA cycle were downregulated, however, genes in the nitrate reduction and gluconeogenesis pathways were upregulated, especially, genes in three pyruvate metabolism pathways. These results suggested that Enterobacter sp. FY-07 could produce energy efficiently under anaerobic conditions to meet the requirement of BC biosynthesis. PMID:26911736

Characterization of the Bacteroides fragilis bfr Gene Product Identifies a Bacterial DPS-Like Protein and Suggests Evolutionary Links in the Ferritin Superfamily

PubMed Central

Gauss, George H.; Reott, Michael A.; Rocha, Edson R.; Young, Mark J.; Douglas, Trevor

2012-01-01

A factor contributing to the pathogenicity of Bacteroides fragilis, the most common anaerobic species isolated from clinical infections, is the bacterium's extreme aerotolerance, which allows survival in oxygenated tissues prior to anaerobic abscess formation. We investigated the role of the bacterioferritin-related (bfr) gene in the B. fragilis oxidative stress response. The bfr mRNA levels are increased in stationary phase or in response to O2 or iron. In addition, bfr null mutants exhibit reduced aerotolerance, and the bfr gene product protects DNA from hydroxyl radical cleavage in vitro. Crystallographic studies revealed a protein with a dodecameric structure and greater similarity to an archaeal DNA protection in starved cells (DPS)-like protein than to the 24-subunit bacterioferritins. Similarity to the DPS-like (DPSL) protein extends to the subunit and includes a pair of conserved cysteine residues juxtaposed to a buried dimetal binding site within the four-helix bundle. Compared to archaeal DPSLs, however, this bacterial DPSL protein contains several unique features, including a significantly different conformation in the C-terminal tail that alters the number and location of pores leading to the central cavity and a conserved metal binding site on the interior surface of the dodecamer. Combined, these characteristics confirm this new class of miniferritin in the bacterial domain, delineate the similarities and differences between bacterial DPSL proteins and their archaeal homologs, allow corrected annotations for B. fragilis bfr and other dpsl genes within the bacterial domain, and suggest an evolutionary link within the ferritin superfamily that connects dodecameric DPS to the (bacterio)ferritin 24-mer. PMID:22020642

Intestinal bacterial signatures of white feces syndrome in shrimp.

PubMed

Hou, Dongwei; Huang, Zhijian; Zeng, Shenzheng; Liu, Jian; Wei, Dongdong; Deng, Xisha; Weng, Shaoping; Yan, Qingyun; He, Jianguo

2018-04-01

Increasing evidence suggests that the intestinal microbiota is closely correlated with the host's health status. Thus, a serious disturbance that disrupts the stability of the intestinal microecosystem could cause host disease. Shrimps are one of the most important products among fishery trading commodities. However, digestive system diseases, such as white feces syndrome (WFS), frequently occur in shrimp culture and have led to enormous economic losses across the world. The WFS occurrences are unclear. Here, we compared intestinal bacterial communities of WFS shrimp and healthy shrimp. Intestinal bacterial communities of WFS shrimp exhibited less diversity but were more heterogeneous than those of healthy shrimp. The intestinal bacterial communities were significantly different between WFS shrimp and healthy shrimp; compared with healthy shrimp, in WFS shrimp, Candidatus Bacilloplasma and Phascolarctobacterium were overrepresented, whereas Paracoccus and Lactococcus were underrepresented. PICRUSt functional predictions indicated that the relative abundances of genes involved in energy metabolism and genetic information processing were significantly greater in WFS shrimp. Collectively, we found that the composition and predicted functions of the intestinal bacterial community were markedly shifted by WFS. Significant increases in Candidatus Bacilloplasma and Phascolarctobacterium and decreases in Paracoccus and Lactococcus may contribute to WFS in shrimp.

Analysis of gene expression levels in individual bacterial cells without image segmentation.

PubMed

Kwak, In Hae; Son, Minjun; Hagen, Stephen J

2012-05-11

Studies of stochasticity in gene expression typically make use of fluorescent protein reporters, which permit the measurement of expression levels within individual cells by fluorescence microscopy. Analysis of such microscopy images is almost invariably based on a segmentation algorithm, where the image of a cell or cluster is analyzed mathematically to delineate individual cell boundaries. However segmentation can be ineffective for studying bacterial cells or clusters, especially at lower magnification, where outlines of individual cells are poorly resolved. Here we demonstrate an alternative method for analyzing such images without segmentation. The method employs a comparison between the pixel brightness in phase contrast vs fluorescence microscopy images. By fitting the correlation between phase contrast and fluorescence intensity to a physical model, we obtain well-defined estimates for the different levels of gene expression that are present in the cell or cluster. The method reveals the boundaries of the individual cells, even if the source images lack the resolution to show these boundaries clearly. Copyright © 2012 Elsevier Inc. All rights reserved.

Potential and use of bacterial small RNAs to combat drug resistance: a systematic review

PubMed Central

Liu, Xiaodong; Zhang, Lin; Wong, Sunny Hei; Chan, Matthew TV; Wu, William KK

2017-01-01

Background Over the decades, new antibacterial agents have been developed in an attempt to combat drug resistance, but they remain unsuccessful. Recently, a novel class of bacterial gene expression regulators, bacterial small RNAs (sRNAs), has received increasing attention toward their involvement in antibiotic resistance. This systematic review aimed to discuss the potential of these small molecules as antibacterial drug targets. Methods Two investigators performed a comprehensive search of MEDLINE, EmBase, and ISI Web of Knowledge from inception to October 2016, without restriction on language. We included all in vitro and in vivo studies investigating the role of bacterial sRNA in antibiotic resistance. Risk of bias of the included studies was assessed by a modified guideline of Systematic Review Center for Laboratory Animal Experimentation (SYRCLE). Results Initial search yielded 432 articles. After exclusion of non-original articles, 20 were included in this review. Of these, all studies examined bacterial-type strains only. There were neither relevant in vivo nor clinical studies. The SYRCLE scores ranged from to 5 to 7, with an average of 5.9. This implies a moderate risk of bias. sRNAs influenced the antibiotics susceptibility through modulation of gene expression relevant to efflux pumps, cell wall synthesis, and membrane proteins. Conclusion Preclinical studies on bacterial-type strains suggest that modulation of sRNAs could enhance bacterial susceptibility to antibiotics. Further studies on clinical isolates and in vivo models are needed to elucidate the therapeutic value of sRNA modulation on treatment of multidrug-resistant bacterial infection. PMID:29290689

Premature terminator analysis sheds light on a hidden world of bacterial transcriptional attenuation.

PubMed

Naville, Magali; Gautheret, Daniel

2010-01-01

Bacterial transcription attenuation occurs through a variety of cis-regulatory elements that control gene expression in response to a wide range of signals. The signal-sensing structures in attenuators are so diverse and rapidly evolving that only a small fraction have been properly annotated and characterized to date. Here we apply a broad-spectrum detection tool in order to achieve a more complete view of the transcriptional attenuation complement of key bacterial species. Our protocol seeks gene families with an unusual frequency of 5' terminators found across multiple species. Many of the detected attenuators are part of annotated elements, such as riboswitches or T-boxes, which often operate through transcriptional attenuation. However, a significant fraction of candidates were not previously characterized in spite of their unmistakable footprint. We further characterized some of these new elements using sequence and secondary structure analysis. We also present elements that may control the expression of several non-homologous genes, suggesting co-transcription and response to common signals. An important class of such elements, which we called mobile attenuators, is provided by 3' terminators of insertion sequences or prophages that may be exapted as 5' regulators when inserted directly upstream of a cellular gene. We show here that attenuators involve a complex landscape of signal-detection structures spanning the entire bacterial domain. We discuss possible scenarios through which these diverse 5' regulatory structures may arise or evolve.

Incorporation of Bacterial Blight Resistance Genes Into Lowland Rice Cultivar Through Marker-Assisted Backcross Breeding.

PubMed

Pradhan, Sharat Kumar; Nayak, Deepak Kumar; Pandit, Elssa; Behera, Lambodar; Anandan, Annamalai; Mukherjee, Arup Kumar; Lenka, Srikanta; Barik, Durga Prasad

2016-07-01

Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is a major disease of rice in many rice growing countries. Pyramided lines carrying two BB resistance gene combinations (Xa21+xa13 and Xa21+xa5) were developed in a lowland cultivar Jalmagna background through backcross breeding by integrating molecular markers. In each backcross generation, markers closely linked to the disease resistance genes were used to select plants possessing the target genes. Background selection was continued in those plants carrying resistant genes until BC(3) generation. Plants having the maximum contribution from the recurrent parent genome were selected in each generation and hybridized with the recipient parent. The BB-pyramided line having the maximum recipient parent genome recovery of 95% was selected among BC3F1 plants and selfed to isolate homozygous BC(3)F(2) plants with different combinations of BB resistance genes. Twenty pyramided lines with two resistance gene combinations exhibited high levels of tolerance against the BB pathogen. In order to confirm the resistance, the pyramided lines were inoculated with different X. oryzae pv. oryzae strains of Odisha for bioassay. The genotypes with combination of two BB resistance genes conferred high levels of resistance to the predominant X. oryzae pv. oryzae isolates prevalent in the region. The pyramided lines showed similarity with the recipient parent with respect to major agro-morphologic traits.

Trait Differentiation within the Fungus-Feeding (Mycophagous) Bacterial Genus Collimonas

PubMed Central

Ballhausen, Max-Bernhard; Vandamme, Peter; de Boer, Wietse

2016-01-01

The genus Collimonas consists of facultative, fungus-feeding (mycophagous) bacteria. To date, 3 species (C. fungivorans, C. pratensis and C. arenae) have been described and over 100 strains have been isolated from different habitats. Functional traits of Collimonas bacteria that are potentially involved in interactions with soil fungi mostly negatively (fungal inhibition e.g.), but also positively (mineral weathering e.g.), affect fungal fitness. We hypothesized that variation in such traits between Collimonas strains leads to different mycophagous bacterial feeding patterns. We investigated a) whether phylogenetically closely related Collimonas strains possess similar traits, b) how far phylogenetic resolution influences the detection of phylogenetic signal (possession of similar traits by related strains) and c) if there is a pattern of co-occurrence among the studied traits. We measured genetically encoded (nifH genes, antifungal collimomycin gene cluster e.g.) as well as phenotypically expressed traits (chitinase- and siderophore production, fungal inhibition and others) and related those to a high-resolution phylogeny (MLSA), constructed by sequencing the housekeeping genes gyrB and rpoB and concatenating those with partial 16S rDNA sequences. Additionally, high-resolution and 16S rDNA derived phylogenies were compared. We show that MLSA is superior to 16SrDNA phylogeny when analyzing trait distribution and relating it to phylogeny at fine taxonomic resolution (a single bacterial genus). We observe that several traits involved in the interaction of collimonads and their host fungus (fungal inhibition e.g.) carry phylogenetic signal. Furthermore, we compare Collimonas trait possession with sister genera like Herbaspirillum and Janthinobacterium. PMID:27309848

Bacterial endophyte communities of three agricultural important grass species differ in their response towards management regimes

NASA Astrophysics Data System (ADS)

Wemheuer, Franziska; Kaiser, Kristin; Karlovsky, Petr; Daniel, Rolf; Vidal, Stefan; Wemheuer, Bernd

2017-01-01

Endophytic bacteria are critical for plant growth and health. However, compositional and functional responses of bacterial endophyte communities towards agricultural practices are still poorly understood. Hence, we analyzed the influence of fertilizer application and mowing frequency on bacterial endophytes in three agriculturally important grass species. For this purpose, we examined bacterial endophytic communities in aerial plant parts of Dactylis glomerata L., Festuca rubra L., and Lolium perenne L. by pyrotag sequencing of bacterial 16S rRNA genes over two consecutive years. Although management regimes influenced endophyte communities, observed responses were grass species-specific. This might be attributed to several bacteria specifically associated with a single grass species. We further predicted functional profiles from obtained 16S rRNA data. These profiles revealed that predicted abundances of genes involved in plant growth promotion or nitrogen metabolism differed between grass species and between management regimes. Moreover, structural and functional community patterns showed no correlation to each other indicating that plant species-specific selection of endophytes is driven by functional rather than phylogenetic traits. The unique combination of 16S rRNA data and functional profiles provided a holistic picture of compositional and functional responses of bacterial endophytes in agricultural relevant grass species towards management practices.

Identification and characterization of rhizospheric microbial diversity by 16S ribosomal RNA gene sequencing.

PubMed

Naveed, Muhammad; Mubeen, Samavia; Khan, SamiUllah; Ahmed, Iftikhar; Khalid, Nauman; Suleria, Hafiz Ansar Rasul; Bano, Asghari; Mumtaz, Abdul Samad

2014-01-01

In the present study, samples of rhizosphere and root nodules were collected from different areas of Pakistan to isolate plant growth promoting rhizobacteria. Identification of bacterial isolates was made by 16S rRNA gene sequence analysis and taxonomical confirmation on EzTaxon Server. The identified bacterial strains were belonged to 5 genera i.e. Ensifer, Bacillus, Pseudomona, Leclercia and Rhizobium. Phylogenetic analysis inferred from 16S rRNA gene sequences showed the evolutionary relationship of bacterial strains with the respective genera. Based on phylogenetic analysis, some candidate novel species were also identified. The bacterial strains were also characterized for morphological, physiological, biochemical tests and glucose dehydrogenase (gdh) gene that involved in the phosphate solublization using cofactor pyrroloquinolone quinone (PQQ). Seven rhizoshperic and 3 root nodulating stains are positive for gdh gene. Furthermore, this study confirms a novel association between microbes and their hosts like field grown crops, leguminous and non-leguminous plants. It was concluded that a diverse group of bacterial population exist in the rhizosphere and root nodules that might be useful in evaluating the mechanisms behind plant microbial interactions and strains QAU-63 and QAU-68 have sequence similarity of 97 and 95% which might be declared as novel after further taxonomic characterization.

Identification and characterization of rhizospheric microbial diversity by 16S ribosomal RNA gene sequencing

PubMed Central

Naveed, Muhammad; Mubeen, Samavia; khan, SamiUllah; Ahmed, Iftikhar; Khalid, Nauman; Suleria, Hafiz Ansar Rasul; Bano, Asghari; Mumtaz, Abdul Samad

2014-01-01

In the present study, samples of rhizosphere and root nodules were collected from different areas of Pakistan to isolate plant growth promoting rhizobacteria. Identification of bacterial isolates was made by 16S rRNA gene sequence analysis and taxonomical confirmation on EzTaxon Server. The identified bacterial strains were belonged to 5 genera i.e. Ensifer, Bacillus, Pseudomona, Leclercia and Rhizobium. Phylogenetic analysis inferred from 16S rRNA gene sequences showed the evolutionary relationship of bacterial strains with the respective genera. Based on phylogenetic analysis, some candidate novel species were also identified. The bacterial strains were also characterized for morphological, physiological, biochemical tests and glucose dehydrogenase (gdh) gene that involved in the phosphate solublization using cofactor pyrroloquinolone quinone (PQQ). Seven rhizoshperic and 3 root nodulating stains are positive for gdh gene. Furthermore, this study confirms a novel association between microbes and their hosts like field grown crops, leguminous and non-leguminous plants. It was concluded that a diverse group of bacterial population exist in the rhizosphere and root nodules that might be useful in evaluating the mechanisms behind plant microbial interactions and strains QAU-63 and QAU-68 have sequence similarity of 97 and 95% which might be declared as novel after further taxonomic characterization. PMID:25477935

A Morpholino-based screen to identify novel genes involved in craniofacial morphogenesis

PubMed Central

Melvin, Vida Senkus; Feng, Weiguo; Hernandez-Lagunas, Laura; Artinger, Kristin Bruk; Williams, Trevor

2014-01-01

BACKGROUND The regulatory mechanisms underpinning facial development are conserved between diverse species. Therefore, results from model systems provide insight into the genetic causes of human craniofacial defects. Previously, we generated a comprehensive dataset examining gene expression during development and fusion of the mouse facial prominences. Here, we used this resource to identify genes that have dynamic expression patterns in the facial prominences, but for which only limited information exists concerning developmental function. RESULTS This set of ~80 genes was used for a high throughput functional analysis in the zebrafish system using Morpholino gene knockdown technology. This screen revealed three classes of cranial cartilage phenotypes depending upon whether knockdown of the gene affected the neurocranium, viscerocranium, or both. The targeted genes that produced consistent phenotypes encoded proteins linked to transcription (meis1, meis2a, tshz2, vgll4l), signaling (pkdcc, vlk, macc1, wu:fb16h09), and extracellular matrix function (smoc2). The majority of these phenotypes were not altered by reduction of p53 levels, demonstrating that both p53 dependent and independent mechanisms were involved in the craniofacial abnormalities. CONCLUSIONS This Morpholino-based screen highlights new genes involved in development of the zebrafish craniofacial skeleton with wider relevance to formation of the face in other species, particularly mouse and human. PMID:23559552

THE INVOLVEMENT OF HUMAN MONOGENIC CARDIOMYOPATHY GENES IN EXPERIMENTAL POLYGENIC CARDIAC HYPERTROPHY.

PubMed

Prestes, Priscilla R; Marques, Francine Z; Lopez-Campos, Guillermo; Lewandowski, Paul; Delbridge, Lea M D; Charchar, Fadi J; Harrap, Stephen B

2018-05-18

Hypertrophic cardiomyopathy thickens heart muscles reducing functionality and increasing risk of cardiac disease and morbidity. Genetic factors are involved, but their contribution is poorly understood. We used the hypertrophic heart rat (HHR), a unique normotensive polygenic model of cardiac hypertrophy and heart failure to investigate the role of genes associated with monogenic human cardiomyopathy. We selected 42 genes involved in monogenic human cardiomyopathies to study: 1) DNA variants, by sequencing the whole-genome of 13-week old HHR and age-matched normal heart rat (NHR), its genetic control strain; 2) mRNA expression, by targeted RNA-sequencing in left ventricles of HHR and NHR at five ages (2-days old, 4-, 13-, 33- and 50-weeks old) compared to human idiopathic dilated data; and 3) microRNA expression, with rat microRNA microarrays in left ventricles of 2-days old HHR and age-matched NHR. We also investigated experimentally validated microRNA-mRNA interactions. Whole-genome sequencing revealed unique variants mostly located in non-coding regions of HHR and NHR. We found 29 genes differentially expressed in at least one age. Genes encoding desmoglein 2 (Dsg2) and transthyretin (Ttr) were significantly differentially expressed at all ages in the HHR, but only Ttr was also differentially expressed in human idiopathic cardiomyopathy. Lastly, only two microRNAs differentially expressed in the HHR were present in our comparison of validated microRNA-mRNA interactions. These two microRNAs interact with five of the genes studied. Our study shows that genes involved in monogenic forms of human cardiomyopathies may also influence polygenic forms of the disease.

Transcriptome Analysis Revealed Changes of Multiple Genes Involved in Haliotis discus hannai Innate Immunity during Vibrio parahemolyticus Infection.

PubMed

Nam, Bo-Hye; Jung, Myunghee; Subramaniyam, Sathiyamoorthy; Yoo, Seung-il; Markkandan, Kesavan; Moon, Ji-Young; Kim, Young-Ok; Kim, Dong-Gyun; An, Cheul Min; Shin, Younhee; Jung, Ho-jin; Park, Jun-hyung

2016-01-01

Abalone (Haliotis discus hannai) is one of the most valuable marine aquatic species in Korea, Japan and China. Tremendous exposure to bacterial infection is common in aquaculture environment, especially by Vibrio sp. infections. It's therefore necessary and urgent to understand the mechanism of H. discus hannai host defense against Vibrio parahemolyticus infection. However studies on its immune system are hindered by the lack of genomic resources. In the present study, we sequenced the transcriptome of control and bacterial challenged H. discus hannai tissues. Totally, 138 MB of reference transcriptome were obtained from de novo assembly of 34 GB clean bases from ten different libraries and annotated with the biological terms (GO and KEGG). A total of 10,575 transcripts exhibiting the differentially expression at least one pair of comparison and the functional annotations highlight genes related to immune response, cell adhesion, immune regulators, redox molecules and mitochondrial coding genes. Mostly, these groups of genes were dominated in hemocytes compared to other tissues. This work is a prerequisite for the identification of those physiological traits controlling H. discus hannai ability to survive against Vibrio infection.

Transcriptome Analysis Revealed Changes of Multiple Genes Involved in Haliotis discus hannai Innate Immunity during Vibrio parahemolyticus Infection

PubMed Central

Nam, Bo-Hye; Jung, Myunghee; Subramaniyam, Sathiyamoorthy; Yoo, Seung-il; Markkandan, Kesavan; Moon, Ji-Young; Kim, Young-Ok; Kim, Dong-Gyun; An, Cheul Min; Shin, Younhee; Jung, Ho-jin; Park, Jun-hyung

2016-01-01

Abalone (Haliotis discus hannai) is one of the most valuable marine aquatic species in Korea, Japan and China. Tremendous exposure to bacterial infection is common in aquaculture environment, especially by Vibrio sp. infections. It’s therefore necessary and urgent to understand the mechanism of H. discus hannai host defense against Vibrio parahemolyticus infection. However studies on its immune system are hindered by the lack of genomic resources. In the present study, we sequenced the transcriptome of control and bacterial challenged H. discus hannai tissues. Totally, 138 MB of reference transcriptome were obtained from de novo assembly of 34 GB clean bases from ten different libraries and annotated with the biological terms (GO and KEGG). A total of 10,575 transcripts exhibiting the differentially expression at least one pair of comparison and the functional annotations highlight genes related to immune response, cell adhesion, immune regulators, redox molecules and mitochondrial coding genes. Mostly, these groups of genes were dominated in hemocytes compared to other tissues. This work is a prerequisite for the identification of those physiological traits controlling H. discus hannai ability to survive against Vibrio infection. PMID:27088873

Low-shear modeled microgravity: a global environmental regulatory signal affecting bacterial gene expression, physiology, and pathogenesis

NASA Technical Reports Server (NTRS)

Nickerson, Cheryl A.; Ott, C. Mark; Wilson, James W.; Ramamurthy, Rajee; LeBlanc, Carly L.; Honer zu Bentrup, Kerstin; Hammond, Timothy; Pierson, Duane L.

2003-01-01

Bacteria inhabit an impressive variety of ecological niches and must adapt constantly to changing environmental conditions. While numerous environmental signals have been examined for their effect on bacteria, the effects of mechanical forces such as shear stress and gravity have only been investigated to a limited extent. However, several important studies have demonstrated a key role for the environmental signals of low shear and/or microgravity in the regulation of bacterial gene expression, physiology, and pathogenesis [Chem. Rec. 1 (2001) 333; Appl. Microbiol. Biotechnol. 54 (2000) 33; Appl. Environ. Microbiol. 63 (1997) 4090; J. Ind. Microbiol. 18 (1997) 22; Curr. Microbiol. 34(4) (1997) 199; Appl. Microbiol. Biotechnol. 56(3-4) (2001) 384; Infect Immun. 68(6) (2000) 3147; Cell 109(7) (2002) 913; Appl. Environ. Microbiol. 68(11) (2002) 5408; Proc. Natl. Acad. Sci. U. S. A. 99(21) (2002) 13807]. The response of bacteria to these environmental signals, which are similar to those encountered during prokaryotic life cycles, may provide insight into bacterial adaptations to physiologically relevant conditions. This review focuses on the current and potential future research trends aimed at understanding the effect of the mechanical forces of low shear and microgravity analogues on different bacterial parameters. In addition, this review also discusses the use of microgravity technology to generate physiologically relevant human tissue models for research in bacterial pathogenesis.

ESTs Analysis Reveals Putative Genes Involved in Symbiotic Seed Germination in Dendrobium officinale

PubMed Central

Zhao, Ming-Ming; Zhang, Gang; Zhang, Da-Wei; Hsiao, Yu-Yun; Guo, Shun-Xing

2013-01-01

Dendrobium officinale (Orchidaceae) is one of the world’s most endangered plants with great medicinal value. In nature, D . officinale seeds must establish symbiotic relationships with fungi to germinate. However, the molecular events involved in the interaction between fungus and plant during this process are poorly understood. To isolate the genes involved in symbiotic germination, a suppression subtractive hybridization (SSH) cDNA library of symbiotically germinated D . officinale seeds was constructed. From this library, 1437 expressed sequence tags (ESTs) were clustered to 1074 Unigenes (including 902 singletons and 172 contigs), which were searched against the NCBI non-redundant (NR) protein database (E-value cutoff, e-5). Based on sequence similarity with known proteins, 579 differentially expressed genes in D . officinale were identified and classified into different functional categories by Gene Ontology (GO), Clusters of orthologous Groups of proteins (COGs) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The expression levels of 15 selected genes emblematic of symbiotic germination were confirmed via real-time quantitative PCR. These genes were classified into various categories, including defense and stress response, metabolism, transcriptional regulation, transport process and signal transduction pathways. All transcripts were upregulated in the symbiotically germinated seeds (SGS). The functions of these genes in symbiotic germination were predicted. Furthermore, two fungus-induced calcium-dependent protein kinases (CDPKs), which were upregulated 6.76- and 26.69-fold in SGS compared with un-germinated seeds (UGS), were cloned from D . officinale and characterized for the first time. This study provides the first global overview of genes putatively involved in D . officinale symbiotic seed germination and provides a foundation for further functional research regarding symbiotic relationships in orchids. PMID:23967335

ESTs analysis reveals putative genes involved in symbiotic seed germination in Dendrobium officinale.

PubMed

Zhao, Ming-Ming; Zhang, Gang; Zhang, Da-Wei; Hsiao, Yu-Yun; Guo, Shun-Xing

2013-01-01

Dendrobiumofficinale (Orchidaceae) is one of the world's most endangered plants with great medicinal value. In nature, D. officinale seeds must establish symbiotic relationships with fungi to germinate. However, the molecular events involved in the interaction between fungus and plant during this process are poorly understood. To isolate the genes involved in symbiotic germination, a suppression subtractive hybridization (SSH) cDNA library of symbiotically germinated D. officinale seeds was constructed. From this library, 1437 expressed sequence tags (ESTs) were clustered to 1074 Unigenes (including 902 singletons and 172 contigs), which were searched against the NCBI non-redundant (NR) protein database (E-value cutoff, e(-5)). Based on sequence similarity with known proteins, 579 differentially expressed genes in D. officinale were identified and classified into different functional categories by Gene Ontology (GO), Clusters of orthologous Groups of proteins (COGs) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The expression levels of 15 selected genes emblematic of symbiotic germination were confirmed via real-time quantitative PCR. These genes were classified into various categories, including defense and stress response, metabolism, transcriptional regulation, transport process and signal transduction pathways. All transcripts were upregulated in the symbiotically germinated seeds (SGS). The functions of these genes in symbiotic germination were predicted. Furthermore, two fungus-induced calcium-dependent protein kinases (CDPKs), which were upregulated 6.76- and 26.69-fold in SGS compared with un-germinated seeds (UGS), were cloned from D. officinale and characterized for the first time. This study provides the first global overview of genes putatively involved in D. officinale symbiotic seed germination and provides a foundation for further functional research regarding symbiotic relationships in orchids.

Bacterial disease management: challenges, experience, innovation and future prospects: Challenges in Bacterial Molecular Plant Pathology.

PubMed

Sundin, George W; Castiblanco, Luisa F; Yuan, Xiaochen; Zeng, Quan; Yang, Ching-Hong

2016-12-01

Plant diseases caused by bacterial pathogens place major constraints on crop production and cause significant annual losses on a global scale. The attainment of consistent effective management of these diseases can be extremely difficult, and management potential is often affected by grower reliance on highly disease-susceptible cultivars because of consumer preferences, and by environmental conditions favouring pathogen development. New and emerging bacterial disease problems (e.g. zebra chip of potato) and established problems in new geographical regions (e.g. bacterial canker of kiwifruit in New Zealand) grab the headlines, but the list of bacterial disease problems with few effective management options is long. The ever-increasing global human population requires the continued stable production of a safe food supply with greater yields because of the shrinking areas of arable land. One major facet in the maintenance of the sustainability of crop production systems with predictable yields involves the identification and deployment of sustainable disease management solutions for bacterial diseases. In addition, the identification of novel management tactics has also come to the fore because of the increasing evolution of resistance to existing bactericides. A number of central research foci, involving basic research to identify critical pathogen targets for control, novel methodologies and methods of delivery, are emerging that will provide a strong basis for bacterial disease management into the future. Near-term solutions are desperately needed. Are there replacement materials for existing bactericides that can provide effective disease management under field conditions? Experience should inform the future. With prior knowledge of bactericide resistance issues evolving in pathogens, how will this affect the deployment of newer compounds and biological controls? Knowledge is critical. A comprehensive understanding of bacterial pathosystems is required to not

Comparative Genomic Analyses of the Bacterial Phosphotransferase System

PubMed Central

Barabote, Ravi D.; Saier, Milton H.

2005-01-01

We report analyses of 202 fully sequenced genomes for homologues of known protein constituents of the bacterial phosphoenolpyruvate-dependent phosphotransferase system (PTS). These included 174 bacterial, 19 archaeal, and 9 eukaryotic genomes. Homologues of PTS proteins were not identified in archaea or eukaryotes, showing that the horizontal transfer of genes encoding PTS proteins has not occurred between the three domains of life. Of the 174 bacterial genomes (136 bacterial species) analyzed, 30 diverse species have no PTS homologues, and 29 species have cytoplasmic PTS phosphoryl transfer protein homologues but lack recognizable PTS permeases. These soluble homologues presumably function in regulation. The remaining 77 species possess all PTS proteins required for the transport and phosphorylation of at least one sugar via the PTS. Up to 3.2% of the genes in a bacterium encode PTS proteins. These homologues were analyzed for family association, range of protein types, domain organization, and organismal distribution. Different strains of a single bacterial species often possess strikingly different complements of PTS proteins. Types of PTS protein domain fusions were analyzed, showing that certain types of domain fusions are common, while others are rare or prohibited. Select PTS proteins were analyzed from different phylogenetic standpoints, showing that PTS protein phylogeny often differs from organismal phylogeny. The results document the frequent gain and loss of PTS protein-encoding genes and suggest that the lateral transfer of these genes within the bacterial domain has played an important role in bacterial evolution. Our studies provide insight into the development of complex multicomponent enzyme systems and lead to predictions regarding the types of protein-protein interactions that promote efficient PTS-mediated phosphoryl transfer. PMID:16339738

Bacterial Degraders of Coexisting Dichloromethane, Benzene, and Toluene, Identified by Stable-Isotope Probing.

PubMed

Yoshikawa, Miho; Zhang, Ming; Kurisu, Futoshi; Toyota, Koki

2017-01-01

Most bioremediation studies on volatile organic compounds (VOCs) have focused on a single contaminant or its derived compounds and degraders have been identified under single contaminant conditions. Bioremediation of multiple contaminants remains a challenging issue. To identify a bacterial consortium that degrades multiple VOCs (dichloromethane (DCM), benzene, and toluene), we applied DNA-stable isotope probing. For individual tests, we combined a 13 C-labeled VOC with other two unlabeled VOCs, and prepared three unlabeled VOCs as a reference. Over 11 days, DNA was periodically extracted from the consortia, and the bacterial community was evaluated by next-generation sequencing of bacterial 16S rRNA gene amplicons. Density gradient fractions of the DNA extracts were amplified by universal bacterial primers for the 16S rRNA gene sequences, and the amplicons were analyzed by terminal restriction fragment length polymorphism (T-RFLP) using restriction enzymes: Hha I and Msp I. The T-RFLP fragments were identified by 16S rRNA gene cloning and sequencing. Under all test conditions, the consortia were dominated by Rhodanobacter , Bradyrhizobium / Afipia , Rhizobium , and Hyphomicrobium . DNA derived from Hyphomicrobium and Propioniferax shifted toward heavier fractions under the condition added with 13 C-DCM and 13 C-benzene, respectively, compared with the reference, but no shifts were induced by 13 C-toluene addition. This implies that Hyphomicrobium and Propioniferax were the main DCM and benzene degraders, respectively, under the coexisting condition. The known benzene degrader Pseudomonas sp. was present but not actively involved in the degradation.

Characterization of an isoproturon mineralizing bacterial culture enriched from a French agricultural soil.

PubMed

Hussain, Sabir; Sørensen, Sebastian R; Devers-Lamrani, Marion; El-Sebai, Talaat; Martin-Laurent, Fabrice

2009-11-01

The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized by a bacterial culture isolated from an agricultural soil regularly exposed to IPU. Molecular analysis of the bacterial culture by DNA fingerprinting, cloning and sequencing of the 16S rRNA genes revealed that it consisted of six different members among whom the dominant was related to Sphingomonas sp. Six bacterial strains belonging to genera Ancylobacter, Pseudomonas, Stenotrophomonas, Methylobacterium, Variovorax and Agrobacterium were isolated from the IPU-degrading culture. None of these were able to degrade IPU in pure culture and only the intact culture sustained the ability to mineralize IPU. The composition of the culture appeared stable suggesting that yet unknown interactions are involved in the IPU mineralization. IPU degradation involved the transitory accumulation of three known IPU metabolites 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, and 4-isopropylaniline and their further degradation. Thus, it indicates a metabolic pathway initiated by two successive N-demethylations, followed by cleavage of the urea side chain. This culture did not degrade other structurally related phenylurea herbicides. The degrading activity of the bacterial culture was deeply influenced by the pH, being completely inhibited at pH 5.5 and optimal at pH 7.5.

Changing bacterial profile of Sundarbans, the world heritage mangrove: impact of anthropogenic interventions.

PubMed

Chakraborty, Arpita; Bera, Amit; Mukherjee, Arghya; Basak, Pijush; Khan, Imroze; Mondal, Arindam; Roy, Arunava; Bhattacharyya, Anish; SenGupta, Sohan; Roy, Debojyoti; Nag, Sudip; Ghosh, Abhrajyoti; Chattopadhyay, Dhrubajyoti; Bhattacharyya, Maitree

2015-04-01

Mangrove microbial communities and their associated activities have profound impact on biogeochemical cycles. Although microbial composition and structure are known to be influenced by biotic and abiotic factors in the mangrove sediments, finding direct correlations between them remains a challenge. In this study we have explored sediment bacterial diversity of the Sundarbans, a world heritage site using a culture-independent molecular approach. Bacterial diversity was analyzed from three different locations with a history of exposure to differential anthropogenic activities. 16S rRNA gene libraries were constructed and partial sequencing of the clones was performed to identify the microbial strains. We identified bacterial strains known to be involved in a variety of biodegradation/biotransformation processes including hydrocarbon degradation, and heavy metal resistance. Canonical Correspondence Analysis of the environmental and exploratory datasets revealed correlations between the ecological indices associated with pollutant levels and bacterial diversity across the sites. Our results indicate that sites with similar exposure of anthropogenic intervention reflect similar patterns of microbial diversity besides spatial commonalities.

Chemotaxis and flagellar genes of Chromobacterium violaceum.

PubMed

Pereira, Maristela; Parente, Juliana Alves; Bataus, Luiz Artur Mendes; Cardoso, Divina das Dores de Paula; Soares, Renata Bastos Ascenço; Soares, Célia Maria de Almeida

2004-03-31

The availability of the complete genome of the Gram-negative beta-proteobacterium Chromobacterium violaceum has increasingly impacted our understanding of this microorganism. This review focuses on the genomic organization and structural analysis of the deduced proteins of the chemosensory adaptation system of C. violaceum. C. violaceum has multiple homologues of most chemotaxis genes, organized mostly in clusters in the bacterial genome. We found at least 67 genes, distributed in 10 gene clusters, involved in the chemotaxis of C. violaceum. A close examination of the chemoreceptors methyl-accepting chemotaxis proteins (MCPs), and the deduced sequences of the members of the two-component signaling system revealed canonical motifs, described as essential for the function of the deduced proteins. The chemoreceptors found in C. violaceum include the complete repertoire of such genes described in bacteria, designated as tsr, tar, trg, and tap; 41 MCP loci were found in the C. violaceum genome. Also, the C. violaceum genome includes a large repertoire of the proteins of the chemosensory transducer system. Multiple homologues of bacterial chemotaxis genes, including CheA, CheB, CheD, CheR, CheV, CheY, CheZ, and CheW, were found in the C. violaceum genome.

Role of the Genes of Type VI Secretion System in Virulence of Rice Bacterial Brown Stripe Pathogen Acidovorax avenae subsp. avenae Strain RS-2

PubMed Central

Masum, Md. Mahidul Islam; Yang, Yingzi; Li, Bin; Olaitan, Ogunyemi Solabomi; Chen, Jie; Zhang, Yang; Fang, Yushi; Qiu, Wen; Wang, Yanli; Sun, Guochang

2017-01-01

The Type VI secretion system (T6SS) is a class of macromolecular machine that is required for the virulence of gram-negative bacteria. However, it is still not clear what the role of T6SS in the virulence of rice bacterial brown stripe pathogen Acidovorax avenae subsp. avenae (Aaa) is. The aim of the current study was to investigate the contribution of T6SS in Aaa strain RS2 virulence using insertional deletion mutation and complementation approaches. This strain produced weak virulence but contains a complete T6SS gene cluster based on a genome-wide analysis. Here we compared the virulence-related phenotypes between the wild-type (RS-2) and 25 T6SS mutants, which were constructed using homologous recombination methods. The mutation of 15 T6SS genes significantly reduced bacterial virulence and the secretion of Hcp protein. Additionally, the complemented 7 mutations ΔpppA, ΔclpB, Δhcp, ΔdotU, ΔicmF, ΔimpJ, and ΔimpM caused similar virulence characteristics as RS-2. Moreover, the mutant ΔpppA, ΔclpB, ΔicmF, ΔimpJ and ΔimpM genes caused by a 38.3~56.4% reduction in biofilm formation while the mutants ΔpppA, ΔclpB, ΔicmF and Δhcp resulted in a 37.5~44.6% reduction in motility. All together, these results demonstrate that T6SS play vital roles in the virulence of strain RS-2, which may be partially attributed to the reductions in Hcp secretion, biofilm formation and motility. However, differences in virulence between strain RS-1 and RS-2 suggest that other factors may also be involved in the virulence of Aaa. PMID:28934168

Pesticide Side Effects in an Agricultural Soil Ecosystem as Measured by amoA Expression Quantification and Bacterial Diversity Changes

PubMed Central

Feld, Louise; Hjelmsø, Mathis Hjort; Nielsen, Morten Schostag; Jacobsen, Anne Dorthe; Rønn, Regin; Ekelund, Flemming; Krogh, Paul Henning; Strobel, Bjarne Westergaard; Jacobsen, Carsten Suhr

2015-01-01

Background and Methods Assessing the effects of pesticide hazards on microbiological processes in the soil is currently based on analyses that provide limited insight into the ongoing processes. This study proposes a more comprehensive approach. The side effects of pesticides may appear as changes in the expression of specific microbial genes or as changes in diversity. To assess the impact of pesticides on gene expression, we focused on the amoA gene, which is involved in ammonia oxidation. We prepared soil microcosms and exposed them to dazomet, mancozeb or no pesticide. We hypothesized that the amount of amoA transcript decreases upon pesticide application, and to test this hypothesis, we used reverse-transcription qPCR. We also hypothesized that bacterial diversity is affected by pesticides. This hypothesis was investigated via 454 sequencing and diversity analysis of the 16S ribosomal RNA and RNA genes, representing the active and total soil bacterial communities, respectively. Results and Conclusion Treatment with dazomet reduced both the bacterial and archaeal amoA transcript numbers by more than two log units and produced long-term effects for more than 28 days. Mancozeb also inhibited the numbers of amoA transcripts, but only transiently. The bacterial and archaeal amoA transcripts were both sensitive bioindicators of pesticide side effects. Additionally, the numbers of bacterial amoA transcripts correlated with nitrate production in N-amended microcosms. Dazomet reduced the total bacterial numbers by one log unit, but the population size was restored after twelve days. The diversity of the active soil bacteria also seemed to be re-established after twelve days. However, the total bacterial diversity as reflected in the 16S ribosomal RNA gene sequences was largely dominated by Firmicutes and Proteobacteria at day twelve, likely reflecting a halt in the growth of early opportunists and the re-establishment of a more diverse population. We observed no

Comparing wastewater chemicals, indicator bacteria concentrations, and bacterial pathogen genes as fecal pollution indicators

USGS Publications Warehouse

Haack, S.K.; Duris, J.W.; Fogarty, L.R.; Kolpin, D.W.; Focazio, M.J.; Furlong, E.T.; Meyer, M.T.

2009-01-01

The objective of this study was to compare fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli [EC], and enterococci [ENT]) concentrations with a wide array of typical organic wastewater chemicals and selected bacterial genes as indicators of fecal pollution in water samples collected at or near 18 surface water drinking water intakes. Genes tested included esp (indicating human-pathogenic ENT) and nine genes associated with various animal sources of shiga-toxin-producing EC (STEC). Fecal pollution was indicated by genes and/or chemicals for 14 of the 18 tested samples, with little relation to FIB standards. Of 13 samples with <50 EC 100 mL-1, human pharmaceuticals or chemical indicators of wastewater treatment plant effluent occurred in six, veterinary antibiotics were detected in three, and stx1 or stx2 genes (indicating varying animal sources of STEC) were detected in eight. Only the EC eaeA gene was positively correlated with FIB concentrations. Human-source fecal pollution was indicated by the esp gene and the human pharmaceutical carbamazepine in one of the nine samples that met all FIB recreational water quality standards. Escherichia coli rfbO157 and stx2c genes, which are typically associated with cattle sources and are of potential human health significance, were detected in one sample in the absence of tested chemicals. Chemical and gene-based indicators of fecal contamination may be present even when FIB standards are met, and some may, unlike FIB, indicate potential sources. Application of multiple water quality indicators with variable environmental persistence and fate may yield greater confidence in fecal pollution assessment and may inform remediation decisions. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Polymorphisms of genes involved in polycyclic aromatic hydrocarbons’ biotransformation and atherosclerosis

PubMed Central

Marinković, Natalija; Pašalić, Daria; Potočki, Slavica

2013-01-01

Polycyclic aromatic hydrocarbons (PAHs) are among the most prevalent environmental pollutants and result from the incomplete combustion of hydrocarbons (coal and gasoline, fossil fuel combustion, byproducts of industrial processing, natural emission, cigarette smoking, etc.). The first phase of xenobiotic biotransformation in the PAH metabolism includes activities of cytochrome P450 from the CYP1 family and microsomal epoxide hydrolase. The products of this biotransformation are reactive oxygen species that are transformed in the second phase through the formation of conjugates with glutathione, glucuronate or sulphates. PAH exposure may lead to PAH-DNA adduct formation or induce an inflammatory atherosclerotic plaque phenotype. Several genetic polymorphisms of genes encoded for enzymes involved in PAH biotransformation have been proven to lead to the development of diseases. Enzyme CYP P450 1A1, which is encoded by the CYP1A1 gene, is vital in the monooxygenation of lipofilic substrates, while GSTM1 and GSTT1 are the most abundant isophorms that conjugate and neutralize oxygen products. Some single nucleotide polymorphisms of the CYP1A1 gene as well as the deletion polymorphisms of GSTT1 and GSTM1 may alter the final specific cellular inflammatory respond. Occupational exposure or conditions from the living environment can contribute to the production of PAH metabolites with adverse effects on human health. The aim of this study was to obtain data on biotransformation and atherosclerosis, as well as data on the gene polymorphisms involved in biotransformation, in order to better study gene expression and further elucidate the interaction between genes and the environment. PMID:24266295

Archaeal and bacterial diversity in two hot springs from geothermal regions in Bulgaria as demostrated by 16S rRNA and GH-57 genes.

PubMed

Stefanova, Katerina; Tomova, Iva; Tomova, Anna; Radchenkova, Nadja; Atanassov, Ivan; Kambourova, Margarita

2015-12-01

Archaeal and bacterial diversity in two Bulgarian hot springs, geographically separated with different tectonic origin and different temperature of water was investigated exploring two genes, 16S rRNA and GH-57. Archaeal diversity was significantly higher in the hotter spring Levunovo (LV) (82°C); on the contrary, bacterial diversity was higher in the spring Vetren Dol (VD) (68°C). The analyzed clones from LV library were referred to twenty eight different sequence types belonging to five archaeal groups from Crenarchaeota and Euryarchaeota. A domination of two groups was observed, Candidate Thaumarchaeota and Methanosarcinales. The majority of the clones from VD were referred to HWCG (Hot Water Crenarchaeotic Group). The formation of a group of thermophiles in the order Methanosarcinales was suggested. Phylogenetic analysis revealed high numbers of novel sequences, more than one third of archaeal and half of the bacterial phylotypes displayed similarity lower than 97% with known ones. The retrieved GH-57 gene sequences showed a complex phylogenic distribution. The main part of the retrieved homologous GH-57 sequences affiliated with bacterial phyla Bacteroidetes, Deltaproteobacteria, Candidate Saccharibacteria and affiliation of almost half of the analyzed sequences is not fully resolved. GH-57 gene analysis allows an increased resolution of the biodiversity assessment and in depth analysis of specific taxonomic groups. [Int Microbiol 18(4):217-223 (2015)]. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

Identification of new developmentally regulated genes involved in Streptomyces coelicolor sporulation.

PubMed

Salerno, Paola; Persson, Jessica; Bucca, Giselda; Laing, Emma; Ausmees, Nora; Smith, Colin P; Flärdh, Klas

2013-12-05

The sporulation of aerial hyphae of Streptomyces coelicolor is a complex developmental process. Only a limited number of the genes involved in this intriguing morphological differentiation programme are known, including some key regulatory genes. The aim of this study was to expand our knowledge of the gene repertoire involved in S. coelicolor sporulation. We report a DNA microarray-based investigation of developmentally controlled gene expression in S. coelicolor. By comparing global transcription patterns of the wild-type parent and two mutants lacking key regulators of aerial hyphal sporulation, we found a total of 114 genes that had significantly different expression in at least one of the two mutants compared to the wild-type during sporulation. A whiA mutant showed the largest effects on gene expression, while only a few genes were specifically affected by whiH mutation. Seven new sporulation loci were investigated in more detail with respect to expression patterns and mutant phenotypes. These included SCO7449-7451 that affect spore pigment biogenesis; SCO1773-1774 that encode an L-alanine dehydrogenase and a regulator-like protein and are required for maturation of spores; SCO3857 that encodes a protein highly similar to a nosiheptide resistance regulator and affects spore maturation; and four additional loci (SCO4421, SCO4157, SCO0934, SCO1195) that show developmental regulation but no overt mutant phenotype. Furthermore, we describe a new promoter-probe vector that takes advantage of the red fluorescent protein mCherry as a reporter of cell type-specific promoter activity. Aerial hyphal sporulation in S. coelicolor is a technically challenging process for global transcriptomic investigations since it occurs only as a small fraction of the colony biomass and is not highly synchronized. Here we show that by comparing a wild-type to mutants lacking regulators that are specifically affecting processes in aerial hypha, it is possible to identify previously

Abundances and profiles of antibiotic resistance genes as well as co-occurrences with human bacterial pathogens in ship ballast tank sediments from a shipyard in Jiangsu Province, China.

PubMed

Lv, Baoyi; Cui, Yuxue; Tian, Wen; Li, Jing; Xie, Bing; Yin, Fang

2018-08-15

Ship ballasting operations may transfer harmful aquatic organisms across global ocean. This study aims to reveal the occurrences and abundances of antibiotic resistance genes (ARGs) and human bacterial pathogens (HBPs) in ballast tank sediments. Nine samples were collected and respectively analyzed by real-time quantitative PCR and high-throughput sequencing technologies. Ten ARGs (aadA1, blaCTX-M, blaTEM, ermB, mefA, strB, sul1, sul2, tetM, and tetQ) and the Class-I integron gene (intI1) were highly prevalent (10 5 -10 9 gene copies/g) in ballast tank sediments. The sul1 was the most abundant ARG with the concentration of 10 8 -10 9 copies/g and intI1 was much more abundant than the ARGs in ballast tank sediments. The strong positive correlations between intI1 and ARGs (blaCTX-M, sul1, sul2 and tetM) indicated the potential spread of ARGs via horizontal gene transfer. In ballast tank sediments, 44 bacterial species were identified as HBPs and accounted for 0.13-21.46% of the total bacterial population although the three indicator pathogenic microbes (Vibrio cholerae, Escherichia coli, and Enterococci) proposed by the International Maritime Organization were not detected. Pseudomonas pseudoalcaligenes, Enterococcus hirae, Shigella sonnei and Bacillus anthracis were the dominant pathogens in ballast tank sediments. Zn and P in sediments had positive effects on the ARGs. Network analysis results indicated that sul1 and sul2 genes existed in several bacterial pathogens. Ballast tank sediments could be regarded as a carrier for the migration of ARGs. It is important to manage ballast tank sediments reasonably in order to prevent the dissemination of ARGs and bacterial pathogens. Copyright © 2018 Elsevier Inc. All rights reserved.

Bacterial community dynamics during bioremediation of diesel oil-contaminated Antarctic soil.

PubMed

Vázquez, S; Nogales, B; Ruberto, L; Hernández, E; Christie-Oleza, J; Lo Balbo, A; Bosch, R; Lalucat, J; Mac Cormack, W

2009-05-01

The effect of nutrient and inocula amendment in a bioremediation field trial using a nutrient-poor Antarctic soil chronically contaminated with hydrocarbons was tested. The analysis of the effects that the treatments caused in bacterial numbers and hydrocarbon removal was combined with the elucidation of the changes occurring on the bacterial community, by 16S rDNA-based terminal restriction fragment length polymorphism (T-RFLP) typing, and the detection of some of the genes involved in the catabolism of hydrocarbons. All treatments caused a significant increase in the number of bacteria able to grow on hydrocarbons and a significant decrease in the soil hydrocarbon content, as compared to the control. However, there were no significant differences between treatments. Comparison of the soil T-RFLP profiles indicated that there were changes in the structure and composition of bacterial communities during the bioremediation trial, although the communities in treated plots were highly similar irrespective of the treatment applied, and they had a similar temporal dynamics. These results showed that nutrient addition was the main factor contributing to the outcome of the bioremediation experiment. This was supported by the lack of evidence of the establishment of inoculated consortia in soils, since their characteristic electrophoretic peaks were only detectable in soil profiles at the beginning of the experiment. Genetic potential for naphthalene degradation, evidenced by detection of nahAc gene, was observed in all soil plots including the control. In treated plots, an increase in the detection of catechol degradation genes (nahH and catA) and in a key gene of denitrification (nosZ) was observed as well. These results indicate that treatments favored the degradation of aromatic hydrocarbons and probably stimulated denitrification, at least transiently. This mesocosm study shows that recovery of chronically contaminated Antarctic soils can be successfully accelerated

Endophytic bacterial diversity in grapevine (Vitis vinifera L.) leaves described by 16S rRNA gene sequence analysis and length heterogeneity-PCR.

PubMed

Bulgari, Daniela; Casati, Paola; Brusetti, Lorenzo; Quaglino, Fabio; Brasca, Milena; Daffonchio, Daniele; Bianco, Piero Attilio

2009-08-01

Diversity of bacterial endophytes associated with grapevine leaf tissues was analyzed by cultivation and cultivation-independent methods. In order to identify bacterial endophytes directly from metagenome, a protocol for bacteria enrichment and DNA extraction was optimized. Sequence analysis of 16S rRNA gene libraries underscored five diverse Operational Taxonomic Units (OTUs), showing best sequence matches with gamma-Proteobacteria, family Enterobacteriaceae, with a dominance of the genus Pantoea. Bacteria isolation through cultivation revealed the presence of six OTUs, showing best sequence matches with Actinobacteria, genus Curtobacterium, and with Firmicutes genera Bacillus and Enterococcus. Length Heterogeneity-PCR (LH-PCR) electrophoretic peaks from single bacterial clones were used to setup a database representing the bacterial endophytes identified in association with grapevine tissues. Analysis of healthy and phytoplasma-infected grapevine plants showed that LH-PCR could be a useful complementary tool for examining the diversity of bacterial endophytes especially for diversity survey on a large number of samples.

Microarray and differential display identify genes involved in jasmonate-dependent anther development.

PubMed

Mandaokar, Ajin; Kumar, V Dinesh; Amway, Matt; Browse, John

2003-07-01

Jasmonate (JA) is a signaling compound essential for anther development and pollen fertility in Arabidopsis. Mutations that block the pathway of JA synthesis result into male sterility. To understand the processes of anther and pollen maturation, we used microarray and differential display approaches to compare gene expression pattern in anthers of wild-type Arabidopsis and the male-sterile mutant, opr3. Microarray experiment revealed 25 genes that were up-regulated more than 1.8-fold in wild-type anthers as compared to mutant anthers. Experiments based on differential display identified 13 additional genes up-regulated in wild-type anthers compared to opr3 for a total of 38 differentially expressed genes. Searches of the Arabidopsis and non-redundant databases disclosed known or likely functions for 28 of the 38 genes identified, while 10 genes encode proteins of unknown function. Northern blot analysis of eight representative clones as probes confirmed low expression in opr3 anthers compared with wild-type anthers. JA responsiveness of these same genes was also investigated by northern blot analysis of anther RNA isolated from wild-type and opr3 plants, In these experiments, four genes were induced in opr3 anthers within 0.5-1 h of JA treatment while the remaining genes were up-regulated only 1-8 h after JA application. None of these genes was induced by JA in anthers of the coil mutant that is deficient in JA responsiveness. The four early-induced genes in opr3 encode lipoxygenase, a putative bHLH transcription factor, epithiospecifier protein and an unknown protein. We propose that these and other early components may be involved in JA signaling and in the initiation of developmental processes. The four late genes encode an extensin-like protein, a peptide transporter and two unknown proteins, which may represent components required later in anther and pollen maturation. Transcript profiling has provided a successful approach to identify genes involved in

When Genome-Based Approach Meets the “Old but Good”: Revealing Genes Involved in the Antibacterial Activity of Pseudomonas sp. P482 against Soft Rot Pathogens

PubMed Central

Krzyżanowska, Dorota M.; Ossowicki, Adam; Rajewska, Magdalena; Maciąg, Tomasz; Jabłońska, Magdalena; Obuchowski, Michał; Heeb, Stephan; Jafra, Sylwia

2016-01-01

Dickeya solani and Pectobacterium carotovorum subsp. brasiliense are recently established species of bacterial plant pathogens causing black leg and soft rot of many vegetables and ornamental plants. Pseudomonas sp. strain P482 inhibits the growth of these pathogens, a desired trait considering the limited measures to combat these diseases. In this study, we determined the genetic background of the antibacterial activity of P482, and established the phylogenetic position of this strain. Pseudomonas sp. P482 was classified as Pseudomonas donghuensis. Genome mining revealed that the P482 genome does not contain genes determining the synthesis of known antimicrobials. However, the ClusterFinder algorithm, designed to detect atypical or novel classes of secondary metabolite gene clusters, predicted 18 such clusters in the genome. Screening of a Tn5 mutant library yielded an antimicrobial negative transposon mutant. The transposon insertion was located in a gene encoding an HpcH/HpaI aldolase/citrate lyase family protein. This gene is located in a hypothetical cluster predicted by the ClusterFinder, together with the downstream homologs of four nfs genes, that confer production of a non-fluorescent siderophore by P. donghuensis HYST. Site-directed inactivation of the HpcH/HpaI aldolase gene, the adjacent short chain dehydrogenase gene, as well as a homolog of an essential nfs cluster gene, all abolished the antimicrobial activity of the P482, suggesting their involvement in a common biosynthesis pathway. However, none of the mutants showed a decreased siderophore yield, neither was the antimicrobial activity of the wild type P482 compromised by high iron bioavailability. A genomic region comprising the nfs cluster and three upstream genes is involved in the antibacterial activity of P. donghuensis P482 against D. solani and P. carotovorum subsp. brasiliense. The genes studied are unique to the two known P. donghuensis strains. This study illustrates that mining of

Riboregulation of bacterial and archaeal transposition.

PubMed

Ellis, Michael J; Haniford, David B

2016-05-01

The coexistence of transposons with their hosts depends largely on transposition levels being tightly regulated to limit the mutagenic burden associated with frequent transposition. For 'DNA-based' (class II) bacterial transposons there is growing evidence that regulation through small noncoding RNAs and/or the RNA-binding protein Hfq are prominent mechanisms of defense against transposition. Recent transcriptomics analyses have identified many new cases of antisense RNAs (asRNA) that potentially could regulate the expression of transposon-encoded genes giving the impression that asRNA regulation of DNA-based transposons is much more frequent than previously thought. Hfq is a highly conserved bacterial protein that plays a central role in posttranscriptional gene regulation and stress response pathways in many bacteria. Three different mechanisms for Hfq-directed control of bacterial transposons have been identified to date highlighting the versatility of this protein as a regulator of bacterial transposons. There is also evidence emerging that some DNA-based transposons encode RNAs that could regulate expression of host genes. In the case of IS200, which appears to have lost its ability to transpose, contributing a regulatory RNA to its host could account for the persistence of this mobile element in a wide range of bacterial species. It remains to be seen how prevalent these transposon-encoded RNA regulators are, but given the relatively large amount of intragenic transcription in bacterial genomes, it would not be surprising if new examples are forthcoming. WIREs RNA 2016, 7:382-398. doi: 10.1002/wrna.1341 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

Identification of bacterial endophytes associated with traditional medicinal plant Tridax procumbens Linn.

PubMed Central

Preveena, Jagadesan; Bhore, Subhash J.

2013-01-01

Background: In traditional medicine, Tridax procumbens Linn. is used in the treatment of injuries and wounds. The bacterial endophytes (BEs) of medicinal plants could produce medicinally important metabolites found in their hosts; and hence, the involvement of BEs in conferring wound healing properties to T. Procumbens cannot be ruled out. But, we do not know which types of BEs are associated with T. Procumbens. Objective: The objective of this study was to investigate the fast growing and cultivable BEs associated with T. procumbens. Materials and Methods: Leaves and stems of healthy T. Procumbens plants were collected and cultivable BEs were isolated from surface-sterilized leaf and stem tissue samples using Luria-Bertani (LB) agar (medium) at standard conditions. A polymerase chain reaction was employed to amplify 16S rRNA coding gene fragments from the isolates. Cultivable endophytic bacterial isolates (EBIs) were identified using 16S rRNA gene nucleotide sequence similarity based method of bacterial identification. Results: Altogether, 50 culturable EBIs were isolated. 16S rRNA gene nucleotide sequences analysis using the Basic Local Alignment Search Tool (BLAST) revealed identities of the EBIs. Analysis reveals that cultivable Bacillus spp., Cronobacter sakazakii, Enterobacter spp., Lysinibacillus sphaericus, Pantoea spp., Pseudomonas spp. and Terribacillus saccharophilus are associated with T. Procumbens. Conclusion: Based on the results, we conclude that 24 different types of culturable BEs are associated with traditionally used medicinal plant, T. Procumbens, and require further study. PMID:24501447

Non-coding-regulatory regions of human brain genes delineated by bacterial artificial chromosome knock-in mice.

PubMed

Schmouth, Jean-François; Castellarin, Mauro; Laprise, Stéphanie; Banks, Kathleen G; Bonaguro, Russell J; McInerny, Simone C; Borretta, Lisa; Amirabbasi, Mahsa; Korecki, Andrea J; Portales-Casamar, Elodie; Wilson, Gary; Dreolini, Lisa; Jones, Steven J M; Wasserman, Wyeth W; Goldowitz, Daniel; Holt, Robert A; Simpson, Elizabeth M

2013-10-14

The next big challenge in human genetics is understanding the 98% of the genome that comprises non-coding DNA. Hidden in this DNA are sequences critical for gene regulation, and new experimental strategies are needed to understand the functional role of gene-regulation sequences in health and disease. In this study, we build upon our HuGX ('high-throughput human genes on the X chromosome') strategy to expand our understanding of human gene regulation in vivo. In all, ten human genes known to express in therapeutically important brain regions were chosen for study. For eight of these genes, human bacterial artificial chromosome clones were identified, retrofitted with a reporter, knocked single-copy into the Hprt locus in mouse embryonic stem cells, and mouse strains derived. Five of these human genes expressed in mouse, and all expressed in the adult brain region for which they were chosen. This defined the boundaries of the genomic DNA sufficient for brain expression, and refined our knowledge regarding the complexity of gene regulation. We also characterized for the first time the expression of human MAOA and NR2F2, two genes for which the mouse homologs have been extensively studied in the central nervous system (CNS), and AMOTL1 and NOV, for which roles in CNS have been unclear. We have demonstrated the use of the HuGX strategy to functionally delineate non-coding-regulatory regions of therapeutically important human brain genes. Our results also show that a careful investigation, using publicly available resources and bioinformatics, can lead to accurate predictions of gene expression.

QTLs for Resistance to Major Rice Diseases Exacerbated by Global Warming: Brown Spot, Bacterial Seedling Rot, and Bacterial Grain Rot.

PubMed

Mizobuchi, Ritsuko; Fukuoka, Shuichi; Tsushima, Seiya; Yano, Masahiro; Sato, Hiroyuki

2016-12-01

In rice (Oryza sativa L.), damage from diseases such as brown spot, caused by Bipolaris oryzae, and bacterial seedling rot and bacterial grain rot, caused by Burkholderia glumae, has increased under global warming because the optimal temperature ranges for growth of these pathogens are relatively high (around 30 °C). Therefore, the need for cultivars carrying genes for resistance to these diseases is increasing to ensure sustainable rice production. In contrast to the situation for other important rice diseases such as blast and bacterial blight, no genes for complete resistance to brown spot, bacterial seedling rot or bacterial grain rot have yet been discovered. Thus, rice breeders have to use partial resistance, which is largely influenced by environmental conditions. Recent progress in molecular genetics and improvement of evaluation methods for disease resistance have facilitated detection of quantitative trait loci (QTLs) associated with resistance. In this review, we summarize the results of worldwide screening for cultivars with resistance to brown spot, bacterial seedling rot and bacterial grain rot and we discuss the identification of QTLs conferring resistance to these diseases in order to provide useful information for rice breeding programs.

The Burkholderia cepacia rpoE gene is not involved in exopolysaccharide production and onion pathogenicity.

PubMed

Devescovi, Giulia; Venturi, Vittorio

2006-03-01

Burkholderia cepacia was originally described as the causative agent of bacterial rot of onions, and it has now emerged as an important opportunistic pathogen causing severe chronic lung infections in patients having cystic fibrosis. Burkholderia cepacia is now classified into nine very closely related species (previously designated as genomovars), all of which have been isolated from both environmental and clinical sources and are collectively known as the B. cepacia complex. The alternative extracytoplasmic function sigma factor, sigmaE, has been determined in several bacterial species as making substantial contributions to bacterial survival under stress conditions. Here, we report the identification and characterization of the rpoE gene, encoding sigmaE, of B. cepacia. It is highly similar to sigmaE of other bacteria, including Escherichia coli and Pseudomonas aeruginosa. Studies using an rpoE knockout mutant of B. cepacia revealed that many stress adaptations, including osmotic, oxidative, desiccation, carbon, and nitrogen stress, were independent of sigmaE. Similarly, biofilm formation; production of exopolysaccharides, N-acyl homoserine lactones, and several exoenzymes; and onion pathogenicity were not affected by the absence of sigmaE. In contrast, sigmaE contributed to the adaptation to heat stress and phosphate starvation.

An epigenetic antimalarial resistance mechanism involving parasite genes linked to nutrient uptake.

PubMed

Sharma, Paresh; Wollenberg, Kurt; Sellers, Morgan; Zainabadi, Kayvan; Galinsky, Kevin; Moss, Eli; Nguitragool, Wang; Neafsey, Daniel; Desai, Sanjay A

2013-07-05

Acquired antimalarial drug resistance produces treatment failures and has led to periods of global disease resurgence. In Plasmodium falciparum, resistance is known to arise through genome-level changes such as mutations and gene duplications. We now report an epigenetic resistance mechanism involving genes responsible for the plasmodial surface anion channel, a nutrient channel that also transports ions and antimalarial compounds at the host erythrocyte membrane. Two blasticidin S-resistant lines exhibited markedly reduced expression of clag genes linked to channel activity, but had no genome-level changes. Silencing aborted production of the channel protein and was directly responsible for reduced uptake. Silencing affected clag paralogs on two chromosomes and was mediated by specific histone modifications, allowing a rapidly reversible drug resistance phenotype advantageous to the parasite. These findings implicate a novel epigenetic resistance mechanism that involves reduced host cell uptake and is a worrisome liability for water-soluble antimalarial drugs.

Growth-rate dependent global effects on gene expression in bacteria

PubMed Central

Klumpp, Stefan; Zhang, Zhongge; Hwa, Terence

2010-01-01

Summary Bacterial gene expression depends not only on specific regulations but also directly on bacterial growth, because important global parameters such as the abundance of RNA polymerases and ribosomes are all growth-rate dependent. Understanding these global effects is necessary for a quantitative understanding of gene regulation and for the robust design of synthetic genetic circuits. The observed growth-rate dependence of constitutive gene expression can be explained by a simple model using the measured growth-rate dependence of the relevant cellular parameters. More complex growth dependences for genetic circuits involving activators, repressors and feedback control were analyzed, and salient features were verified experimentally using synthetic circuits. The results suggest a novel feedback mechanism mediated by general growth-dependent effects and not requiring explicit gene regulation, if the expressed protein affects cell growth. This mechanism can lead to growth bistability and promote the acquisition of important physiological functions such as antibiotic resistance and tolerance (persistence). PMID:20064380

Multilevel Regulation of Bacterial Gene Expression with the Combined STAR and Antisense RNA System.

PubMed

Lee, Young Je; Kim, Soo-Jung; Moon, Tae Seok

2018-03-16

Synthetic small RNA regulators have emerged as a versatile tool to predictably control bacterial gene expression. Owing to their simple design principles, small size, and highly orthogonal behavior, these engineered genetic parts have been incorporated into genetic circuits. However, efforts to achieve more sophisticated cellular functions using RNA regulators have been hindered by our limited ability to integrate different RNA regulators into complex circuits. Here, we present a combined RNA regulatory system in Escherichia coli that uses small transcription activating RNA (STAR) and antisense RNA (asRNA) to activate or deactivate target gene expression in a programmable manner. Specifically, we demonstrated that the activated target output by the STAR system can be deactivated by expressing two different types of asRNAs: one binds to and sequesters the STAR regulator, affecting the transcription process, while the other binds to the target mRNA, affecting the translation process. We improved deactivation efficiencies (up to 96%) by optimizing each type of asRNA and then integrating the two optimized asRNAs into a single circuit. Furthermore, we demonstrated that the combined STAR and asRNA system can control gene expression in a reversible way and can regulate expression of a gene in the genome. Lastly, we constructed and simultaneously tested two A AND NOT B logic gates in the same cell to show sophisticated multigene regulation by the combined system. Our approach establishes a methodology for integrating multiple RNA regulators to rationally control multiple genes.

Bacterial responses to antibiotics and their combinations.

PubMed

Mitosch, Karin; Bollenbach, Tobias

2014-12-01

Antibiotics affect bacterial cell physiology at many levels. Rather than just compensating for the direct cellular defects caused by the drug, bacteria respond to antibiotics by changing their morphology, macromolecular composition, metabolism, gene expression and possibly even their mutation rate. Inevitably, these processes affect each other, resulting in a complex response with changes in the expression of numerous genes. Genome-wide approaches can thus help in gaining a comprehensive understanding of bacterial responses to antibiotics. In addition, a combination of experimental and theoretical approaches is needed for identifying general principles that underlie these responses. Here, we review recent progress in our understanding of bacterial responses to antibiotics and their combinations, focusing on effects at the levels of growth rate and gene expression. We concentrate on studies performed in controlled laboratory conditions, which combine promising experimental techniques with quantitative data analysis and mathematical modeling. While these basic research approaches are not immediately applicable in the clinic, uncovering the principles and mechanisms underlying bacterial responses to antibiotics may, in the long term, contribute to the development of new treatment strategies to cope with and prevent the rise of resistant pathogenic bacteria.

Central role of a bacterial two-component gene regulatory system of previously unknown function in pathogen persistence in human saliva.

PubMed

Shelburne, Samuel A; Sumby, Paul; Sitkiewicz, Izabela; Granville, Chanel; DeLeo, Frank R; Musser, James M

2005-11-01

The molecular genetic mechanisms used by bacteria to persist in humans are poorly understood. Group A Streptococcus (GAS) causes the majority of bacterial pharyngitis cases in humans and is prone to persistently inhabit the upper respiratory tract. To gain information about how GAS survives in and infects the oropharynx, we analyzed the transcriptome of a serotype M1 strain grown in saliva. The dynamic pattern of changes in transcripts of genes [spy0874/0875, herein named sptR and sptS (sptR/S), for saliva persistence] encoding a two-component gene regulatory system of unknown function suggested that SptR/S contributed to persistence of GAS in saliva. Consistent with this idea, an isogenic nonpolar mutant strain (DeltasptR) was dramatically less able to survive in saliva compared with the parental strain. Iterative expression microarray analysis of bacteria grown in saliva revealed that transcripts of several known and putative GAS virulence factor genes were decreased significantly in the DeltasptR mutant strain. Compared with the parental strain, the isogenic mutant strain also had altered transcripts of multiple genes encoding proteins involved in complex carbohydrate acquisition and utilization pathways. Western immunoblot analysis and real-time PCR analysis of GAS in throat swabs taken from humans with pharyngitis confirmed the findings. We conclude that SptR/S optimizes persistence of GAS in human saliva, apparently by strategically influencing metabolic pathways and virulence factor production. The discovery of a genetic program that significantly increased persistence of a major human pathogen in saliva enhances understanding of how bacteria survive in the host and suggests new therapeutic strategies.

Transcriptome Sequencing of Codonopsis pilosula and Identification of Candidate Genes Involved in Polysaccharide Biosynthesis

PubMed Central

Gao, Jian Ping; Wang, Dong; Cao, Ling Ya; Sun, Hai Feng

2015-01-01

Background Codonopsis pilosula (Franch.) Nannf. is one of the most widely used medicinal plants. Although chemical and pharmacological studies have shown that codonopsis polysaccharides (CPPs) are bioactive compounds and that their composition is variable, their biosynthetic pathways remain largely unknown. Next-generation sequencing is an efficient and high-throughput technique that allows the identification of candidate genes involved in secondary metabolism. Principal Findings To identify the components involved in CPP biosynthesis, a transcriptome library, prepared using root and other tissues, was assembled with the help of Illumina sequencing. A total of 9.2 Gb of clean nucleotides was obtained comprising 91,175,044 clean reads, 102,125 contigs, and 45,511 unigenes. After aligning the sequences to the public protein databases, 76.1% of the unigenes were annotated. Among these annotated unigenes, 26,189 were assigned to Gene Ontology categories, 11,415 to Clusters of Orthologous Groups, and 18,848 to Kyoto Encyclopedia of Genes and Genomes pathways. Analysis of abundance of transcripts in the library showed that genes, including those encoding metallothionein, aquaporin, and cysteine protease that are related to stress responses, were in the top list. Among genes involved in the biosynthesis of CPP, those responsible for the synthesis of UDP-L-arabinose and UDP-xylose were highly expressed. Significance To our knowledge, this is the first study to provide a public transcriptome dataset prepared from C. pilosula and an outline of the biosynthetic pathway of polysaccharides in a medicinal plant. Identified candidate genes involved in CPP biosynthesis provide understanding of the biosynthesis and regulation of CPP at the molecular level. PMID:25719364

Impact of training sets on classification of high-throughput bacterial 16s rRNA gene surveys

PubMed Central

Werner, Jeffrey J; Koren, Omry; Hugenholtz, Philip; DeSantis, Todd Z; Walters, William A; Caporaso, J Gregory; Angenent, Largus T; Knight, Rob; Ley, Ruth E

2012-01-01

Taxonomic classification of the thousands–millions of 16S rRNA gene sequences generated in microbiome studies is often achieved using a naïve Bayesian classifier (for example, the Ribosomal Database Project II (RDP) classifier), due to favorable trade-offs among automation, speed and accuracy. The resulting classification depends on the reference sequences and taxonomic hierarchy used to train the model; although the influence of primer sets and classification algorithms have been explored in detail, the influence of training set has not been characterized. We compared classification results obtained using three different publicly available databases as training sets, applied to five different bacterial 16S rRNA gene pyrosequencing data sets generated (from human body, mouse gut, python gut, soil and anaerobic digester samples). We observed numerous advantages to using the largest, most diverse training set available, that we constructed from the Greengenes (GG) bacterial/archaeal 16S rRNA gene sequence database and the latest GG taxonomy. Phylogenetic clusters of previously unclassified experimental sequences were identified with notable improvements (for example, 50% reduction in reads unclassified at the phylum level in mouse gut, soil and anaerobic digester samples), especially for phylotypes belonging to specific phyla (Tenericutes, Chloroflexi, Synergistetes and Candidate phyla TM6, TM7). Trimming the reference sequences to the primer region resulted in systematic improvements in classification depth, and greatest gains at higher confidence thresholds. Phylotypes unclassified at the genus level represented a greater proportion of the total community variation than classified operational taxonomic units in mouse gut and anaerobic digester samples, underscoring the need for greater diversity in existing reference databases. PMID:21716311

Transposon Mutagenesis of the Plant-Associated Bacillus amyloliquefaciens ssp. plantarum FZB42 Revealed That the nfrA and RBAM17410 Genes Are Involved in Plant-Microbe-Interactions

PubMed Central

Dietel, Kristin; Beator, Barbara; Dolgova, Olga; Fan, Ben; Bleiss, Wilfrid; Ziegler, Jörg; Schmid, Michael; Hartmann, Anton; Borriss, Rainer

2014-01-01

Bacillus amyloliquefaciens ssp. plantarum FZB42 represents the prototype of Gram-positive plant growth promoting and biocontrol bacteria. In this study, we applied transposon mutagenesis to generate a transposon library, which was screened for genes involved in multicellular behavior and biofilm formation on roots as a prerequisite of plant growth promoting activity. Transposon insertion sites were determined by rescue-cloning followed by DNA sequencing. As in B. subtilis, the global transcriptional regulator DegU was identified as an activator of genes necessary for swarming and biofilm formation, and the DegU-mutant of FZB42 was found impaired in efficient root colonization. Direct screening of 3,000 transposon insertion mutants for plant-growth-promotion revealed the gene products of nfrA and RBAM_017140 to be essential for beneficial effects exerted by FZB42 on plants. We analyzed the performance of GFP-labeled wild-type and transposon mutants in the colonization of lettuce roots using confocal laser scanning microscopy. While the wild-type strain heavily colonized root surfaces, the nfrA mutant did not colonize lettuce roots, although it was not impaired in growth in laboratory cultures, biofilm formation and swarming motility on agar plates. The RBAM17410 gene, occurring in only a few members of the B. subtilis species complex, was directly involved in plant growth promotion. None of the mutant strains were affected in producing the plant growth hormone auxin. We hypothesize that the nfrA gene product is essential for overcoming the stress caused by plant response towards bacterial root colonization. PMID:24847778

Bacterial community composition in the water column of a lake formed by a former uranium open pit mine.

PubMed

Edberg, Frida; Andersson, Anders F; Holmström, Sara J M

2012-11-01

Mining of pyrite minerals is a major environmental issue involving both biological and geochemical processes. Here we present a study of an artificial lake of a former uranium open pit mine with the aim to connect the chemistry and bacterial community composition (454-pyrosequencing of 16S rRNA genes) in the stratified water column. A shift in the water chemistry from oxic conditions in the epilimnion to anoxic, alkaline, and metal and sulfide-rich conditions in the hypolimnion was corresponded by a strong shift in the bacterial community, with few shared operational taxonomic units (OTU) between the water layers. The epilimnetic bacterial community of the lake (~20 years old) showed similarities to other temperate freshwater lakes, while the hypolimnetic bacterial community showed similarity to extreme chemical environments. The epilimnetic bacterial community had dominance of Actinobacteria and Betaproteobacteria. The hypolimnion displayed a higher bacterial diversity and was dominated by the phototrophic green sulphur bacterium of the genus Chlorobium (ca. 40 % of the total community). Deltaproteobacteria were only represented in the hypolimnion and the most abundant OTUs were affiliated with ferric iron and sulfate reducers of the genus Geobacter and Desulfobulbus, respectively. The chemistry is clearly controlling, especially the hypolimnetic, bacterial community but the community composition also indicates that the bacteria are involved in metal cycling in the lake.

Genes involved in host-parasite interactions can be revealed by their correlated expression.

PubMed

Reid, Adam James; Berriman, Matthew

2013-02-01

Molecular interactions between a parasite and its host are key to the ability of the parasite to enter the host and persist. Our understanding of the genes and proteins involved in these interactions is limited. To better understand these processes it would be advantageous to have a range of methods to predict pairs of genes involved in such interactions. Correlated gene expression profiles can be used to identify molecular interactions within a species. Here we have extended the concept to different species, showing that genes with correlated expression are more likely to encode proteins, which directly or indirectly participate in host-parasite interaction. We go on to examine our predictions of molecular interactions between the malaria parasite and both its mammalian host and insect vector. Our approach could be applied to study any interaction between species, for example, between a host and its parasites or pathogens, but also symbiotic and commensal pairings.

Phylogenetic analysis of genes involved in mycosporine-like amino acid biosynthesis in symbiotic dinoflagellates.

PubMed

Rosic, Nedeljka N

2012-04-01

Mycosporine-like amino acids (MAAs) are multifunctional secondary metabolites involved in photoprotection in many marine organisms. As well as having broad ultraviolet (UV) absorption spectra (310-362 nm), these biological sunscreens are also involved in the prevention of oxidative stress. More than 20 different MAAs have been discovered so far, characterized by distinctive chemical structures and a broad ecological distribution. Additionally, UV-screening MAA metabolites have been investigated and used in biotechnology and cosmetics. The biosynthesis of MAAs has been suggested to occur via either the shikimate or pentose phosphate pathways. Despite their wide distribution in marine and freshwater species and also the commercial application in cosmetic products, there are still a number of uncertainties regarding the genetic, biochemical, and evolutionary origin of MAAs. Here, using a transcriptome-mining approach, we identify the gene counterparts from the shikimate or pentose phosphate pathway involved in MAA biosynthesis within the sequences of the reef-building coral symbiotic dinoflagellates (genus Symbiodinium). We also report the highly similar sequences of genes from the proposed MAA biosynthetic pathway involved in the metabolism of 4-deoxygadusol (direct MAA precursor) in various Symbiodinium strains confirming their algal origin and conserved nature. Finally, we reveal the separate identity of two O-methyltransferase genes, possibly involved in MAA biosynthesis, as well as nonribosomal peptide synthetase and adenosine triphosphate grasp homologs in symbiotic dinoflagellates. This study provides a biochemical and phylogenetic overview of the genes from the proposed MAA biosynthetic pathway with a focus on coral endosymbionts.

Gene-environment interaction involving recently identified colorectal cancer susceptibility loci

PubMed Central

Kantor, Elizabeth D.; Hutter, Carolyn M.; Minnier, Jessica; Berndt, Sonja I.; Brenner, Hermann; Caan, Bette J.; Campbell, Peter T.; Carlson, Christopher S.; Casey, Graham; Chan, Andrew T.; Chang-Claude, Jenny; Chanock, Stephen J.; Cotterchio, Michelle; Du, Mengmeng; Duggan, David; Fuchs, Charles S.; Giovannucci, Edward L.; Gong, Jian; Harrison, Tabitha A.; Hayes, Richard B.; Henderson, Brian E.; Hoffmeister, Michael; Hopper, John L.; Jenkins, Mark A.; Jiao, Shuo; Kolonel, Laurence N.; Le Marchand, Loic; Lemire, Mathieu; Ma, Jing; Newcomb, Polly A.; Ochs-Balcom, Heather M.; Pflugeisen, Bethann M.; Potter, John D.; Rudolph, Anja; Schoen, Robert E.; Seminara, Daniela; Slattery, Martha L.; Stelling, Deanna L.; Thomas, Fridtjof; Thornquist, Mark; Ulrich, Cornelia M.; Warnick, Greg S.; Zanke, Brent W.; Peters, Ulrike; Hsu, Li; White, Emily

2014-01-01

BACKGROUND Genome-wide association studies have identified several single nucleotide polymorphisms (SNPs) that are associated with risk of colorectal cancer (CRC). Prior research has evaluated the presence of gene-environment interaction involving the first 10 identified susceptibility loci, but little work has been conducted on interaction involving SNPs at recently identified susceptibility loci, including: rs10911251, rs6691170, rs6687758, rs11903757, rs10936599, rs647161, rs1321311, rs719725, rs1665650, rs3824999, rs7136702, rs11169552, rs59336, rs3217810, rs4925386, and rs2423279. METHODS Data on 9160 cases and 9280 controls from the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO) and Colon Cancer Family Registry (CCFR) were used to evaluate the presence of interaction involving the above-listed SNPs and sex, body mass index (BMI), alcohol consumption, smoking, aspirin use, post-menopausal hormone (PMH) use, as well as intake of dietary calcium, dietary fiber, dietary folate, red meat, processed meat, fruit, and vegetables. Interaction was evaluated using a fixed-effects meta-analysis of an efficient Empirical Bayes estimator, and permutation was used to account for multiple comparisons. RESULTS None of the permutation-adjusted p-values reached statistical significance. CONCLUSIONS The associations between recently identified genetic susceptibility loci and CRC are not strongly modified by sex, BMI, alcohol, smoking, aspirin, PMH use, and various dietary factors. IMPACT Results suggest no evidence of strong gene-environment interactions involving the recently identified 16 susceptibility loci for CRC taken one at a time. PMID:24994789

Detection of a Mixed Infection in a Culture-Negative Brain Abscess by Broad-Spectrum Bacterial 16S rRNA Gene PCR ▿ †

PubMed Central

Keller, Peter M.; Rampini, Silvana K.; Bloemberg, Guido V.

2010-01-01

We describe the identification of two bacterial pathogens from a culture-negative brain abscess by the use of broad-spectrum 16S rRNA gene PCR. Simultaneous detection of Fusobacterium nucleatum and Porphyromonas endodontalis was possible due to a 24-bp length difference of their partially amplified 16S rRNA genes, which allowed separation by high-resolution polyacrylamide gel electrophoresis. PMID:20392909

Bacterial Quorum Sensing and Microbial Community Interactions

PubMed Central

2018-01-01

ABSTRACT Many bacteria use a cell-cell communication system called quorum sensing to coordinate population density-dependent changes in behavior. Quorum sensing involves production of and response to diffusible or secreted signals, which can vary substantially across different types of bacteria. In many species, quorum sensing modulates virulence functions and is important for pathogenesis. Over the past half-century, there has been a significant accumulation of knowledge of the molecular mechanisms, signal structures, gene regulons, and behavioral responses associated with quorum-sensing systems in diverse bacteria. More recent studies have focused on understanding quorum sensing in the context of bacterial sociality. Studies of the role of quorum sensing in cooperative and competitive microbial interactions have revealed how quorum sensing coordinates interactions both within a species and between species. Such studies of quorum sensing as a social behavior have relied on the development of “synthetic ecological” models that use nonclonal bacterial populations. In this review, we discuss some of these models and recent advances in understanding how microbes might interact with one another using quorum sensing. The knowledge gained from these lines of investigation has the potential to guide studies of microbial sociality in natural settings and the design of new medicines and therapies to treat bacterial infections. PMID:29789364

Transcription profiling provides insights into gene pathways involved in horn and scurs development in cattle

PubMed Central

2010-01-01

Background Two types of horns are evident in cattle - fixed horns attached to the skull and a variation called scurs, which refers to small loosely attached horns. Cattle lacking horns are referred to as polled. Although both the Poll and Scurs loci have been mapped to BTA1 and 19 respectively, the underlying genetic basis of these phenotypes is unknown, and so far, no candidate genes regulating these developmental processes have been described. This study is the first reported attempt at transcript profiling to identify genes and pathways contributing to horn and scurs development in Brahman cattle, relative to polled counterparts. Results Expression patterns in polled, horned and scurs tissues were obtained using the Agilent 44 k bovine array. The most notable feature when comparing transcriptional profiles of developing horn tissues against polled was the down regulation of genes coding for elements of the cadherin junction as well as those involved in epidermal development. We hypothesize this as a key event involved in keratinocyte migration and subsequent horn development. In the polled-scurs comparison, the most prevalent differentially expressed transcripts code for genes involved in extracellular matrix remodelling, which were up regulated in scurs tissues relative to polled. Conclusion For this first time we describe networks of genes involved in horn and scurs development. Interestingly, we did not observe differential expression in any of the genes present on the fine mapped region of BTA1 known to contain the Poll locus. PMID:20537189

Genes involved in prostate cancer progression determine MRI visibility

PubMed Central

Li, Ping; You, Sungyong; Nguyen, Christopher; Wang, Yanping; Kim, Jayoung; Sirohi, Deepika; Ziembiec, Asha; Luthringer, Daniel; Lin, Shih-Chieh; Daskivich, Timothy; Wu, Jonathan; Freeman, Michael R; Saouaf, Rola; Li, Debiao; Kim, Hyung L.

2018-01-01

MRI is used to image prostate cancer and target tumors for biopsy or therapeutic ablation. The objective was to understand the biology of tumors not visible on MRI that may go undiagnosed and untreated. Methods: Prostate cancers visible or invisible on multiparametric MRI were macrodissected and examined by RNAseq. Differentially expressed genes (DEGs) based on MRI visibility status were cross-referenced with publicly available gene expression databases to identify genes associated with disease progression. Genes with potential roles in determining MRI visibility and disease progression were knocked down in murine prostate cancer xenografts, and imaged by MRI. Results: RNAseq identified 1,654 DEGs based on MRI visibility status. Comparison of DEGs based on MRI visibility and tumor characteristics revealed that Gleason score (dissimilarity test, p<0.0001) and tumor size (dissimilarity test, p<0.039) did not completely determine MRI visibility. Genes in previously reported prognostic signatures significantly correlated with MRI visibility suggesting that MRI visibility was prognostic. Cross-referencing DEGs with external datasets identified four genes (PHYHD1, CENPF, ALDH2, GDF15) that predict MRI visibility, progression free survival and metastatic deposits. Genetic modification of a human prostate cancer cell line to induce miR-101 and suppress CENPF decreased cell migration and invasion. As prostate cancer xenografts in mice, these cells had decreased visibility on diffusion weighted MRI and decreased perfusion, which correlated with immunostaining showing decreased cell density and proliferation. Conclusions: Genes involved in prostate cancer prognosis and metastasis determine MRI visibility, indicating that MRI visibility has prognostic significance. MRI visibility was associated with genetic features linked to poor prognosis. PMID:29556354

Evolution of Genes Involved in Gamete Interaction: Evidence for Positive Selection, Duplications and Losses in Vertebrates

PubMed Central

Callebaut, Isabelle; Laurin, Michel; Pascal, Géraldine; Poupon, Anne; Goudet, Ghylène; Monget, Philippe

2012-01-01

Genes encoding proteins involved in sperm-egg interaction and fertilization exhibit a particularly fast evolution and may participate in prezygotic species isolation [1], [2]. Some of them (ZP3, ADAM1, ADAM2, ACR and CD9) have individually been shown to evolve under positive selection [3], [4], suggesting a role of positive Darwinian selection on sperm-egg interaction. However, the genes involved in this biological function have not been systematically and exhaustively studied with an evolutionary perspective, in particular across vertebrates with internal and external fertilization. Here we show that 33 genes among the 69 that have been experimentally shown to be involved in fertilization in at least one taxon in vertebrates are under positive selection. Moreover, we identified 17 pseudogenes and 39 genes that have at least one duplicate in one species. For 15 genes, we found neither positive selection, nor gene copies or pseudogenes. Genes of teleosts, especially genes involved in sperm-oolemma fusion, appear to be more frequently under positive selection than genes of birds and eutherians. In contrast, pseudogenization, gene loss and gene gain are more frequent in eutherians. Thus, each of the 19 studied vertebrate species exhibits a unique signature characterized by gene gain and loss, as well as position of amino acids under positive selection. Reflecting these clade-specific signatures, teleosts and eutherian mammals are recovered as clades in a parsimony analysis. Interestingly the same analysis places Xenopus apart from teleosts, with which it shares the primitive external fertilization, and locates it along with amniotes (which share internal fertilization), suggesting that external or internal environmental conditions of germ cell interaction may not be the unique factors that drive the evolution of fertilization genes. Our work should improve our understanding of the fertilization process and on the establishment of reproductive barriers, for example by

Bacterial Community Diversity of Oil-Contaminated Soils Assessed by High Throughput Sequencing of 16S rRNA Genes.

PubMed

Peng, Mu; Zi, Xiaoxue; Wang, Qiuyu

2015-09-24

Soil bacteria play a major role in ecological and biodegradable function processes in oil-contaminated soils. Here, we assessed the bacterial diversity and changes therein in oil-contaminated soils exposed to different periods of oil pollution using 454 pyrosequencing of 16S rRNA genes. No less than 24,953 valid reads and 6246 operational taxonomic units (OTUs) were obtained from all five studied samples. OTU richness was relatively higher in contaminated soils than clean samples. Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Planctomycetes and Proteobacteria were the dominant phyla among all the soil samples. The heatmap plot depicted the relative percentage of each bacterial family within each sample and clustered five samples into two groups. For the samples, bacteria in the soils varied at different periods of oil exposure. The oil pollution exerted strong selective pressure to propagate many potentially petroleum degrading bacteria. Redundancy analysis (RDA) indicated that organic matter was the highest determinant factor for explaining the variations in community compositions. This suggests that compared to clean soils, oil-polluted soils support more diverse bacterial communities and soil bacterial community shifts were mainly controlled by organic matter and exposure time. These results provide some useful information for bioremediation of petroleum contaminated soil in the future.

Fitness and Recovery of Bacterial Communities and Antibiotic Resistance Genes in Urban Wastewaters Exposed to Classical Disinfection Treatments.

PubMed

Di Cesare, Andrea; Fontaneto, Diego; Doppelbauer, Julia; Corno, Gianluca

2016-09-20

Antibiotic resistance genes (ARGs) are increasingly appreciated to be important as micropollutants. Indirectly produced by human activities, they are released into the environment, as they are untargeted by conventional wastewater treatments. In order to understand the fate of ARGs and of other resistant forms (e.g., phenotypical adaptations) in urban wastewater treatment plants (WWTPs), we monitored three WWTPs with different disinfection processes (chlorine, peracetic acid (PAA), and ultraviolet light (UV)). We monitored WWTPs influx and pre- and postdisinfection effluent over 24 h, followed by incubation experiments lasting for 96 h. We measured bacterial abundance, size distribution and aggregational behavior, the proportion of intact (active) cells, and the abundances of four ARGs and of the mobile element integron1. While all the predisinfection treatments of all WWTPs removed the majority of bacteria and of associated ARGs, of the disinfection processes only PAA efficiently removed bacterial cells. However, the stress imposed by PAA selected for bacterial aggregates and, similarly to chlorine, stimulated the selection of ARGs during the incubation experiment. This suggests disinfections based on chemically aggressive destruction of bacterial cell structures can promote a residual microbial community that is more resistant to antibiotics and, given the altered aggregational behavior, to competitive stress in nature.

Use of 16S rRNA Gene for Identification of a Broad Range of Clinically Relevant Bacterial Pathogens

PubMed Central

Srinivasan, Ramya; Karaoz, Ulas; Volegova, Marina; MacKichan, Joanna; Kato-Maeda, Midori; Miller, Steve; Nadarajan, Rohan; Brodie, Eoin L.; Lynch, Susan V.

2015-01-01

According to World Health Organization statistics of 2011, infectious diseases remain in the top five causes of mortality worldwide. However, despite sophisticated research tools for microbial detection, rapid and accurate molecular diagnostics for identification of infection in humans have not been extensively adopted. Time-consuming culture-based methods remain to the forefront of clinical microbial detection. The 16S rRNA gene, a molecular marker for identification of bacterial species, is ubiquitous to members of this domain and, thanks to ever-expanding databases of sequence information, a useful tool for bacterial identification. In this study, we assembled an extensive repository of clinical isolates (n = 617), representing 30 medically important pathogenic species and originally identified using traditional culture-based or non-16S molecular methods. This strain repository was used to systematically evaluate the ability of 16S rRNA for species level identification. To enable the most accurate species level classification based on the paucity of sequence data accumulated in public databases, we built a Naïve Bayes classifier representing a diverse set of high-quality sequences from medically important bacterial organisms. We show that for species identification, a model-based approach is superior to an alignment based method. Overall, between 16S gene based and clinical identities, our study shows a genus-level concordance rate of 96% and a species-level concordance rate of 87.5%. We point to multiple cases of probable clinical misidentification with traditional culture based identification across a wide range of gram-negative rods and gram-positive cocci as well as common gram-negative cocci. PMID:25658760

Genome-wide analysis of bacterial determinants of plant growth promotion and induced systemic resistance by Pseudomonas fluorescens.

PubMed

Cheng, Xu; Etalo, Desalegn W; van de Mortel, Judith E; Dekkers, Ester; Nguyen, Linh; Medema, Marnix H; Raaijmakers, Jos M

2017-11-01

Pseudomonas fluorescens strain SS101 (Pf.SS101) promotes growth of Arabidopsis thaliana, enhances greening and lateral root formation, and induces systemic resistance (ISR) against the bacterial pathogen Pseudomonas syringae pv. tomato (Pst). Here, targeted and untargeted approaches were adopted to identify bacterial determinants and underlying mechanisms involved in plant growth promotion and ISR by Pf.SS101. Based on targeted analyses, no evidence was found for volatiles, lipopeptides and siderophores in plant growth promotion by Pf.SS101. Untargeted, genome-wide analyses of 7488 random transposon mutants of Pf.SS101 led to the identification of 21 mutants defective in both plant growth promotion and ISR. Many of these mutants, however, were auxotrophic and impaired in root colonization. Genetic analysis of three mutants followed by site-directed mutagenesis, genetic complementation and plant bioassays revealed the involvement of the phosphogluconate dehydratase gene edd, the response regulator gene colR and the adenylsulfate reductase gene cysH in both plant growth promotion and ISR. Subsequent comparative plant transcriptomics analyses strongly suggest that modulation of sulfur assimilation, auxin biosynthesis and transport, steroid biosynthesis and carbohydrate metabolism in Arabidopsis are key mechanisms linked to growth promotion and ISR by Pf.SS101. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Abundance and Diversity of Bacterial Nitrifiers and Denitrifiers and Their Functional Genes in Tannery Wastewater Treatment Plants Revealed by High-Throughput Sequencing

PubMed Central

Wang, Zhu; Zhang, Xu-Xiang; Lu, Xin; Liu, Bo; Li, Yan; Long, Chao; Li, Aimin

2014-01-01

Biological nitrification/denitrification is frequently used to remove nitrogen from tannery wastewater containing high concentrations of ammonia. However, information is limited about the bacterial nitrifiers and denitrifiers and their functional genes in tannery wastewater treatment plants (WWTPs) due to the low-throughput of the previously used methods. In this study, 454 pyrosequencing and Illumina high-throughput sequencing, combined with molecular methods, were used to comprehensively characterize structures and functions of nitrification and denitrification bacterial communities in aerobic and anaerobic sludge of two full-scale tannery WWTPs. Pyrosequencing of 16S rRNA genes showed that Proteobacteria and Synergistetes dominated in the aerobic and anaerobic sludge, respectively. Ammonia-oxidizing bacteria (AOB) amoA gene cloning revealed that Nitrosomonas europaea dominated the ammonia-oxidizing community in the WWTPs. Metagenomic analysis showed that the denitrifiers mainly included the genera of Thauera, Paracoccus, Hyphomicrobium, Comamonas and Azoarcus, which may greatly contribute to the nitrogen removal in the two WWTPs. It is interesting that AOB and ammonia-oxidizing archaea had low abundance although both WWTPs demonstrated high ammonium removal efficiency. Good correlation between the qPCR and metagenomic analysis is observed for the quantification of functional genes amoA, nirK, nirS and nosZ, indicating that the metagenomic approach may be a promising method used to comprehensively investigate the abundance of functional genes of nitrifiers and denitrifiers in the environment. PMID:25420093

Structure and function of Helicobacter pylori CagA, the first-identified bacterial protein involved in human cancer

PubMed Central

HATAKEYAMA, Masanori

2017-01-01

Chronic infection with Helicobacter pylori cagA-positive strains is the strongest risk factor of gastric cancer. The cagA gene-encoded CagA protein is delivered into gastric epithelial cells via bacterial type IV secretion, where it undergoes tyrosine phosphorylation at the Glu-Pro-Ile-Tyr-Ala (EPIYA) motifs. Delivered CagA then acts as a non-physiological scaffold/hub protein by interacting with multiple host signaling molecules, most notably the pro-oncogenic phosphatase SHP2 and the polarity-regulating kinase PAR1/MARK, in both tyrosine phosphorylation-dependent and -independent manners. CagA-mediated manipulation of intracellular signaling promotes neoplastic transformation of gastric epithelial cells. Transgenic expression of CagA in experimental animals has confirmed the oncogenic potential of the bacterial protein. Structural polymorphism of CagA influences its scaffold function, which may underlie the geographic difference in the incidence of gastric cancer. Since CagA is no longer required for the maintenance of established gastric cancer cells, studying the role of CagA during neoplastic transformation will provide an excellent opportunity to understand molecular processes underlying “Hit-and-Run” carcinogenesis. PMID:28413197

Vizantin inhibits bacterial adhesion without affecting bacterial growth and causes Streptococcus mutans biofilm to detach by altering its internal architecture.

PubMed

Takenaka, Shoji; Oda, Masataka; Domon, Hisanori; Ohsumi, Tatsuya; Suzuki, Yuki; Ohshima, Hayato; Yamamoto, Hirofumi; Terao, Yutaka; Noiri, Yuichiro

2016-11-11

An ideal antibiofilm strategy is to control both in the quality and quantity of biofilm while maintaining the benefits derived from resident microflora. Vizantin, a recently developed immunostimulating compound, has also been found to have antibiofilm property. This study evaluated the influence on biofilm formation of Streptococcus mutans in the presence of sulfated vizantin and biofilm development following bacterial adhesion on a hydroxyapatite disc coated with sulfated vizantin. Supplementation with sulfated vizantin up to 50 μM did not affect either bacterial growth or biofilm formation, whereas 50 μM sulfated vizantin caused the biofilm to readily detach from the surface. Sulfated vizantin at the concentration of 50 μM upregulated the expression of the gtfB and gtfC genes, but downregulated the expression of the gtfD gene, suggesting altered architecture in the biofilm. Biofilm development on the surface coated with sulfated vizantin was inhibited depending on the concentration, suggesting prevention from bacterial adhesion. Among eight genes related to bacterial adherence in S. mutans, expression of gtfB and gtfC was significantly upregulated, whereas the expression of gtfD, GbpA and GbpC was downregulated according to the concentration of vizantin, especially with 50 μM vizantin by 0.8-, 0.4-, and 0.4-fold, respectively. These findings suggest that sulfated vizantin may cause structural degradation as a result of changing gene regulation related to bacterial adhesion and glucan production of S. mutans. Copyright © 2016 Elsevier Inc. All rights reserved.

SPARTA: Simple Program for Automated reference-based bacterial RNA-seq Transcriptome Analysis.

PubMed

Johnson, Benjamin K; Scholz, Matthew B; Teal, Tracy K; Abramovitch, Robert B

2016-02-04

Many tools exist in the analysis of bacterial RNA sequencing (RNA-seq) transcriptional profiling experiments to identify differentially expressed genes between experimental conditions. Generally, the workflow includes quality control of reads, mapping to a reference, counting transcript abundance, and statistical tests for differentially expressed genes. In spite of the numerous tools developed for each component of an RNA-seq analysis workflow, easy-to-use bacterially oriented workflow applications to combine multiple tools and automate the process are lacking. With many tools to choose from for each step, the task of identifying a specific tool, adapting the input/output options to the specific use-case, and integrating the tools into a coherent analysis pipeline is not a trivial endeavor, particularly for microbiologists with limited bioinformatics experience. To make bacterial RNA-seq data analysis more accessible, we developed a Simple Program for Automated reference-based bacterial RNA-seq Transcriptome Analysis (SPARTA). SPARTA is a reference-based bacterial RNA-seq analysis workflow application for single-end Illumina reads. SPARTA is turnkey software that simplifies the process of analyzing RNA-seq data sets, making bacterial RNA-seq analysis a routine process that can be undertaken on a personal computer or in the classroom. The easy-to-install, complete workflow processes whole transcriptome shotgun sequencing data files by trimming reads and removing adapters, mapping reads to a reference, counting gene features, calculating differential gene expression, and, importantly, checking for potential batch effects within the data set. SPARTA outputs quality analysis reports, gene feature counts and differential gene expression tables and scatterplots. SPARTA provides an easy-to-use bacterial RNA-seq transcriptional profiling workflow to identify differentially expressed genes between experimental conditions. This software will enable microbiologists with

Bacterial group II introns: not just splicing.

PubMed

Toro, Nicolás; Jiménez-Zurdo, José Ignacio; García-Rodríguez, Fernando Manuel

2007-04-01

Group II introns are both catalytic RNAs (ribozymes) and mobile retroelements that were discovered almost 14 years ago. It has been suggested that eukaryotic mRNA introns might have originated from the group II introns present in the alphaproteobacterial progenitor of the mitochondria. Bacterial group II introns are of considerable interest not only because of their evolutionary significance, but also because they could potentially be used as tools for genetic manipulation in biotechnology and for gene therapy. This review summarizes what is known about the splicing mechanisms and mobility of bacterial group II introns, and describes the recent development of group II intron-based gene-targetting methods. Bacterial group II intron diversity, evolutionary relationships, and behaviour in bacteria are also discussed.

Evolutionary Genomics of Genes Involved in Olfactory Behavior in the Drosophila melanogaster Species Group

PubMed Central

Lavagnino, Nicolás; Serra, François; Arbiza, Leonardo; Dopazo, Hernán; Hasson, Esteban

2012-01-01

Previous comparative genomic studies of genes involved in olfactory behavior in Drosophila focused only on particular gene families such as odorant receptor and/or odorant binding proteins. However, olfactory behavior has a complex genetic architecture that is orchestrated by many interacting genes. In this paper, we present a comparative genomic study of olfactory behavior in Drosophila including an extended set of genes known to affect olfactory behavior. We took advantage of the recent burst of whole genome sequences and the development of powerful statistical tools to analyze genomic data and test evolutionary and functional hypotheses of olfactory genes in the six species of the Drosophila melanogaster species group for which whole genome sequences are available. Our study reveals widespread purifying selection and limited incidence of positive selection on olfactory genes. We show that the pace of evolution of olfactory genes is mostly independent of the life cycle stage, and of the number of life cycle stages, in which they participate in olfaction. However, we detected a relationship between evolutionary rates and the position that the gene products occupy in the olfactory system, genes occupying central positions tend to be more constrained than peripheral genes. Finally, we demonstrate that specialization to one host does not seem to be associated with bursts of adaptive evolution in olfactory genes in D. sechellia and D. erecta, the two specialists species analyzed, but rather different lineages have idiosyncratic evolutionary histories in which both historical and ecological factors have been involved. PMID:22346339

The LBP Gene and Its Association with Resistance to Aeromonas hydrophila in Tilapia

PubMed Central

Fu, Gui Hong; Liu, Feng; Xia, Jun Hong; Yue, Gen Hua

2014-01-01

Resistance to pathogens is important for the sustainability and profitability of food fish production. In immune-related genes, the lipopolysaccharide-binding protein (LBP) gene is an important mediator of the inflammatory reaction. We analyzed the cDNA and genomic structure of the LBP gene in tilapia. The full-length cDNA (1901 bp) of the gene contained a 1416 bp open reading frame, encoding 471 amino acid residues. Its genomic sequence was 5577 bp, comprising 15 exons and 14 introns. Under normal conditions, the gene was constitutively expressed in all examined tissues. The highest expression was detected in intestine and kidney. We examined the responses of the gene to challenges with two bacterial pathogens Streptcoccus agalactiae and Aeromonas hydrophila. The gene was significantly upregulated in kidney and spleen post-infection with S. agalactiae and A. hydrophila, respectively. However, the expression profiles of the gene after the challenge with the two pathogens were different. Furthermore, we identified three SNPs in the gene. There were significant associations (p < 0.05) of two of the three SNPs with the resistance to A. hydrophila, but not with the resistance to S. agalactiae or growth performance. These results suggest that the LBP gene is involved in the acute-phase immunologic response to the bacterial infections, and the responses to the two bacterial pathogens are different. The two SNPs associated with the resistance to A. hydrophila may be useful in the selection of tilapia resistant to A. hydrophila. PMID:25470022

Bacterial symbionts and natural products.

PubMed

Crawford, Jason M; Clardy, Jon

2011-07-21

The study of bacterial symbionts of eukaryotic hosts has become a powerful discovery engine for chemistry. This highlight looks at four case studies that exemplify the range of chemistry and biology involved in these symbioses: a bacterial symbiont of a fungus and a marine invertebrate that produce compounds with significant anticancer activity, and bacterial symbionts of insects and nematodes that produce compounds that regulate multilateral symbioses.

Transcriptome analysis identifies genes involved in ethanol response of Saccharomyces cerevisiae in Agave tequilana juice.

PubMed

Ramirez-Córdova, Jesús; Drnevich, Jenny; Madrigal-Pulido, Jaime Alberto; Arrizon, Javier; Allen, Kirk; Martínez-Velázquez, Moisés; Alvarez-Maya, Ikuri

2012-08-01

During ethanol fermentation, yeast cells are exposed to stress due to the accumulation of ethanol, cell growth is altered and the output of the target product is reduced. For Agave beverages, like tequila, no reports have been published on the global gene expression under ethanol stress. In this work, we used microarray analysis to identify Saccharomyces cerevisiae genes involved in the ethanol response. Gene expression of a tequila yeast strain of S. cerevisiae (AR5) was explored by comparing global gene expression with that of laboratory strain S288C, both after ethanol exposure. Additionally, we used two different culture conditions, cells grown in Agave tequilana juice as a natural fermentation media or grown in yeast-extract peptone dextrose as artificial media. Of the 6368 S. cerevisiae genes in the microarray, 657 genes were identified that had different expression responses to ethanol stress due to strain and/or media. A cluster of 28 genes was found over-expressed specifically in the AR5 tequila strain that could be involved in the adaptation to tequila yeast fermentation, 14 of which are unknown such as yor343c, ylr162w, ygr182c, ymr265c, yer053c-a or ydr415c. These could be the most suitable genes for transforming tequila yeast to increase ethanol tolerance in the tequila fermentation process. Other genes involved in response to stress (RFC4, TSA1, MLH1, PAU3, RAD53) or transport (CYB2, TIP20, QCR9) were expressed in the same cluster. Unknown genes could be good candidates for the development of recombinant yeasts with ethanol tolerance for use in industrial tequila fermentation.

Molecular genetics of Erwinia amylovora involved in the development of fire blight.

PubMed

Oh, Chang-Sik; Beer, Steven V

2005-12-15

The bacterial plant pathogen, Erwinia amylovora, causes the devastating disease known as fire blight in some Rosaceous plants like apple, pear, quince, raspberry and several ornamentals. Knowledge of the factors affecting the development of fire blight has mushroomed in the last quarter century. On the molecular level, genes encoding a Hrp type III secretion system, genes encoding enzymes involved in synthesis of extracellular polysaccharides and genes facilitating the growth of E. amylovora in its host plants have been characterized. The Hrp pathogenicity island, delimited by genes suggesting horizontal gene transfer, is composed of four distinct regions, the hrp/hrc region, the HEE (Hrp effectors and elicitors) region, the HAE (Hrp-associated enzymes) region, and the IT (Island transfer) region. The Hrp pathogenicity island encodes a Hrp type III secretion system (TTSS), which delivers several proteins from bacteria to plant apoplasts or cytoplasm. E. amylovora produces two exopolysaccharides, amylovoran and levan, which cause the characteristic fire blight wilting symptom in host plants. In addition, other genes, and their encoded proteins, have been characterized as virulence factors of E. amylovora that encode enzymes facilitating sorbitol metabolism, proteolytic activity and iron harvesting. This review summarizes our understanding of the genes and gene products of E. amylovora that are involved in the development of the fire blight disease.

An Evolutionary Genomic Approach to Identify Genes Involved in Human Birth Timing

PubMed Central

Orabona, Guilherme; Morgan, Thomas; Haataja, Ritva; Hallman, Mikko; Puttonen, Hilkka; Menon, Ramkumar; Kuczynski, Edward; Norwitz, Errol; Snegovskikh, Victoria; Palotie, Aarno; Fellman, Vineta; DeFranco, Emily A.; Chaudhari, Bimal P.; McGregor, Tracy L.; McElroy, Jude J.; Oetjens, Matthew T.; Teramo, Kari; Borecki, Ingrid; Fay, Justin; Muglia, Louis

2011-01-01

Coordination of fetal maturation with birth timing is essential for mammalian reproduction. In humans, preterm birth is a disorder of profound global health significance. The signals initiating parturition in humans have remained elusive, due to divergence in physiological mechanisms between humans and model organisms typically studied. Because of relatively large human head size and narrow birth canal cross-sectional area compared to other primates, we hypothesized that genes involved in parturition would display accelerated evolution along the human and/or higher primate phylogenetic lineages to decrease the length of gestation and promote delivery of a smaller fetus that transits the birth canal more readily. Further, we tested whether current variation in such accelerated genes contributes to preterm birth risk. Evidence from allometric scaling of gestational age suggests human gestation has been shortened relative to other primates. Consistent with our hypothesis, many genes involved in reproduction show human acceleration in their coding or adjacent noncoding regions. We screened >8,400 SNPs in 150 human accelerated genes in 165 Finnish preterm and 163 control mothers for association with preterm birth. In this cohort, the most significant association was in FSHR, and 8 of the 10 most significant SNPs were in this gene. Further evidence for association of a linkage disequilibrium block of SNPs in FSHR, rs11686474, rs11680730, rs12473870, and rs1247381 was found in African Americans. By considering human acceleration, we identified a novel gene that may be associated with preterm birth, FSHR. We anticipate other human accelerated genes will similarly be associated with preterm birth risk and elucidate essential pathways for human parturition. PMID:21533219

Distribution, diversity and abundance of bacterial laccase-like genes in different particle size fractions of sediments in a subtropical mangrove ecosystem.

PubMed

Luo, Ling; Zhou, Zhi-Chao; Gu, Ji-Dong

2015-10-01

This study investigated the diversity and abundance of bacterial lacasse-like genes in different particle size fractions, namely sand, silt, and clay of sediments in a subtropical mangrove ecosystem. Moreover, the effects of nutrient conditions on bacterial laccase-like communities as well as the correlation between nutrients and, both the abundance and diversity indices of laccase-like bacteria in particle size fractions were also studied. Compared to bulk sediments, Bacteroidetes, Caldithrix, Cyanobacteria and Chloroflexi were dominated in all 3 particle-size fractions of intertidal sediment (IZ), but Actinobacteria and Firmicutes were lost after the fractionation procedures used. The diversity index of IZ fractions decreased in the order of bulk > clay > silt > sand. In fractions of mangrove forest sediment (MG), Verrucomicrobia was found in silt, and both Actinobacteria and Bacteroidetes appeared in clay, but no new species were found in sand. The declining order of diversity index in MG fractions was clay > silt > sand > bulk. Furthermore, the abundance of lacasse-like bacteria varied with different particle-size fractions significantly (p < 0.05), and decreased in the order of sand > clay > silt in both IZ and MG fractions. Additionally, nutrient availability was found to significantly affect the diversity and community structure of laccase-like bacteria (p < 0.05), while the total organic carbon contents were positively related to the abundance of bacterial laccase-like genes in particle size fractions (p < 0.05). Therefore, this study further provides evidence that bacterial laccase plays a vital role in turnover of sediment organic matter and cycling of nutrients.

Agricultural Freshwater Pond Supports Diverse and Dynamic Bacterial and Viral Populations

PubMed Central

Chopyk, Jessica; Allard, Sarah; Nasko, Daniel J.; Bui, Anthony; Mongodin, Emmanuel F.; Sapkota, Amy R.

2018-01-01

Agricultural ponds have a great potential as a means of capture and storage of water for irrigation. However, pond topography (small size, shallow depth) leaves them susceptible to environmental, agricultural, and anthropogenic exposures that may influence microbial dynamics. Therefore, the aim of this project was to characterize the bacterial and viral communities of pond water in the Mid-Atlantic United States with a focus on the late season (October–December), where decreasing temperature and nutrient levels can affect the composition of microbial communities. Ten liters of freshwater from an agricultural pond were sampled monthly, and filtered sequentially through 1 and 0.2 μm filter membranes. Total DNA was then extracted from each filter, and the bacterial communities were characterized using 16S rRNA gene sequencing. The remaining filtrate was chemically concentrated for viruses, DNA-extracted, and shotgun sequenced. Bacterial community profiling showed significant fluctuations over the sampling period, corresponding to changes in the condition of the pond freshwater (e.g., pH, nutrient load). In addition, there were significant differences in the alpha-diversity and core bacterial operational taxonomic units (OTUs) between water fractions filtered through different pore sizes. The viral fraction was dominated by tailed bacteriophage of the order Caudovirales, largely those of the Siphoviridae family. Moreover, while present, genes involved in virulence/antimicrobial resistance were not enriched within the viral fraction during the study period. Instead, the viral functional profile was dominated by phage associated proteins, as well as those related to nucleotide production. Overall, these data suggest that agricultural pond water harbors a diverse core of bacterial and bacteriophage species whose abundance and composition are influenced by environmental variables characteristic of pond topology and the late season. PMID:29740420

Ribosome reinitiation at leader peptides increases translation of bacterial proteins.

PubMed

Korolev, Semen A; Zverkov, Oleg A; Seliverstov, Alexandr V; Lyubetsky, Vassily A

2016-04-16

Short leader genes usually do not encode stable proteins, although their importance in expression control of bacterial genomes is widely accepted. Such genes are often involved in the control of attenuation regulation. However, the abundance of leader genes suggests that their role in bacteria is not limited to regulation. Specifically, we hypothesize that leader genes increase the expression of protein-coding (structural) genes via ribosome reinitiation at the leader peptide in the case of a short distance between the stop codon of the leader gene and the start codon of the structural gene. For instance, in Actinobacteria, the frequency of leader genes at a distance of 10-11 bp is about 70 % higher than the mean frequency within the 1 to 65 bp range; and it gradually decreases as the range grows longer. A pronounced peak of this frequency-distance relationship is also observed in Proteobacteria, Bacteroidetes, Spirochaetales, Acidobacteria, the Deinococcus-Thermus group, and Planctomycetes. In contrast, this peak falls to the distance of 15-16 bp and is not very pronounced in Firmicutes; and no such peak is observed in cyanobacteria and tenericutes. Generally, this peak is typical for many bacteria. Some leader genes located close to a structural gene probably play a regulatory role as well.

Bacterial Influences on Animal Origins

PubMed Central

Alegado, Rosanna A.; King, Nicole

2014-01-01

Animals evolved in seas teeming with bacteria, yet the influences of bacteria on animal origins are poorly understood. Comparisons among modern animals and their closest living relatives, the choanoflagellates, suggest that the first animals used flagellated collar cells to capture bacterial prey. The cell biology of prey capture, such as cell adhesion between predator and prey, involves mechanisms that may have been co-opted to mediate intercellular interactions during the evolution of animal multicellularity. Moreover, a history of bacterivory may have influenced the evolution of animal genomes by driving the evolution of genetic pathways for immunity and facilitating lateral gene transfer. Understanding the interactions between bacteria and the progenitors of animals may help to explain the myriad ways in which bacteria shape the biology of modern animals, including ourselves. PMID:25280764

Evolutionary genomics: transdomain gene transfers.

PubMed

Bordenstein, Seth R

2007-11-06

Biologists have until now conceded that bacterial gene transfer to multicellular animals is relatively uncommon in Nature. A new study showing promiscuous insertions of bacterial endosymbiont genes into invertebrate genomes ushers in a shift in this paradigm.

Bacterial identification and subtyping using DNA microarray and DNA sequencing.

PubMed

Al-Khaldi, Sufian F; Mossoba, Magdi M; Allard, Marc M; Lienau, E Kurt; Brown, Eric D

2012-01-01

The era of fast and accurate discovery of biological sequence motifs in prokaryotic and eukaryotic cells is here. The co-evolution of direct genome sequencing and DNA microarray strategies not only will identify, isotype, and serotype pathogenic bacteria, but also it will aid in the discovery of new gene functions by detecting gene expressions in different diseases and environmental conditions. Microarray bacterial identification has made great advances in working with pure and mixed bacterial samples. The technological advances have moved beyond bacterial gene expression to include bacterial identification and isotyping. Application of new tools such as mid-infrared chemical imaging improves detection of hybridization in DNA microarrays. The research in this field is promising and future work will reveal the potential of infrared technology in bacterial identification. On the other hand, DNA sequencing by using 454 pyrosequencing is so cost effective that the promise of $1,000 per bacterial genome sequence is becoming a reality. Pyrosequencing technology is a simple to use technique that can produce accurate and quantitative analysis of DNA sequences with a great speed. The deposition of massive amounts of bacterial genomic information in databanks is creating fingerprint phylogenetic analysis that will ultimately replace several technologies such as Pulsed Field Gel Electrophoresis. In this chapter, we will review (1) the use of DNA microarray using fluorescence and infrared imaging detection for identification of pathogenic bacteria, and (2) use of pyrosequencing in DNA cluster analysis to fingerprint bacterial phylogenetic trees.

Gene transfer agents: phage-like elements of genetic exchange

PubMed Central

Lang, Andrew S.; Zhaxybayeva, Olga; Beatty, J. Thomas

2013-01-01

Horizontal gene transfer is important in the evolution of bacterial and archaeal genomes. An interesting genetic exchange process is carried out by diverse phage-like gene transfer agents (GTAs) that are found in a wide range of prokaryotes. Although GTAs resemble phages, they lack the hallmark capabilities that define typical phages, and they package random pieces of the producing cell’s genome. In this Review, we discuss the defining characteristics of the GTAs that have been identified to date, along with potential functions for these agents and the possible evolutionary forces that act on the genes involved in their production. PMID:22683880

Rapid Expansion of Immune-Related Gene Families in the House Fly, Musca domestica

PubMed Central

Lazzaro, Brian P.; Clark, Andrew G.

2017-01-01

Abstract The house fly, Musca domestica, occupies an unusual diversity of potentially septic niches compared with other sequenced Dipteran insects and is a vector of numerous diseases of humans and livestock. In the present study, we apply whole-transcriptome sequencing to identify genes whose expression is regulated in adult flies upon bacterial infection. We then combine the transcriptomic data with analysis of rates of gene duplication and loss to provide insight into the evolutionary dynamics of immune-related genes. Genes up-regulated after bacterial infection are biased toward being evolutionarily recent innovations, suggesting the recruitment of novel immune components in the M. domestica or ancestral Dipteran lineages. In addition, using new models of gene family evolution, we show that several different classes of immune-related genes, particularly those involved in either pathogen recognition or pathogen killing, are duplicating at a significantly accelerated rate on the M. domestica lineage relative to other Dipterans. Taken together, these results suggest that the M. domestica immune response includes an elevated diversity of genes, perhaps as a consequence of its lifestyle in septic environments. PMID:28087775

UGT-29 protein expression and localization during bacterial infection in Caenorhabditis elegans

NASA Astrophysics Data System (ADS)

Wong, Rui-Rui; Lee, Song-Hua; Nathan, Sheila

2014-09-01

The nematode Caenorhabditis elegans is routinely used as an animal model to delineate complex molecular mechanisms involved in the host response to pathogen infection. Following up on an earlier study on host-pathogen interaction, we constructed a ugt-29::GFP transcriptional fusion transgenic worm strain to examine UGT-29 protein expression and localization upon bacterial infection. UGT-29 orthologs can be found in higher organisms including humans and is proposed as a member of the UDP-Glucoronosyl Transferase family of proteins which are involved in phase II detoxification of compounds detrimental to the host organism. Under uninfected conditions, UGT-29::GFP fusion protein was highly expressed in the C. elegans anterior pharynx and intestine, two major organs involved in detoxification. We further evaluated the localization of the enzyme in worms infected with the bacterial pathogen, Burkholderia pseudomallei. The infected ugt-29::GFP transgenic strain exhibited increased fluorescence in the pharynx and intestine with pronounced fluorescence also extending to body wall muscle. This transcriptional fusion GFP transgenic worm is a convenient and direct tool to provide information on UGT detoxification enzyme gene expression and could be a useful tool for a number of diverse applications.

Bacterial Genome Instability

PubMed Central

Darmon, Elise

2014-01-01

SUMMARY Bacterial genomes are remarkably stable from one generation to the next but are plastic on an evolutionary time scale, substantially shaped by horizontal gene transfer, genome rearrangement, and the activities of mobile DNA elements. This implies the existence of a delicate balance between the maintenance of genome stability and the tolerance of genome instability. In this review, we describe the specialized genetic elements and the endogenous processes that contribute to genome instability. We then discuss the consequences of genome instability at the physiological level, where cells have harnessed instability to mediate phase and antigenic variation, and at the evolutionary level, where horizontal gene transfer has played an important role. Indeed, this ability to share DNA sequences has played a major part in the evolution of life on Earth. The evolutionary plasticity of bacterial genomes, coupled with the vast numbers of bacteria on the planet, substantially limits our ability to control disease. PMID:24600039

High level bacterial contamination of secondary school students' mobile phones.

PubMed

Kõljalg, Siiri; Mändar, Rando; Sõber, Tiina; Rööp, Tiiu; Mändar, Reet

2017-06-01

While contamination of mobile phones in the hospital has been found to be common in several studies, little information about bacterial abundance on phones used in the community is available. Our aim was to quantitatively determine the bacterial contamination of secondary school students' mobile phones. Altogether 27 mobile phones were studied. The contact plate method and microbial identification using MALDI-TOF mass spectrometer were used for culture studies. Quantitative PCR reaction for detection of universal 16S rRNA, Enterococcus faecalis 16S rRNA and Escherichia coli allantoin permease were performed, and the presence of tetracycline ( tet A, tet B, tet M), erythromycin ( erm B) and sulphonamide ( sul 1) resistance genes was assessed. We found a high median bacterial count on secondary school students' mobile phones (10.5 CFU/cm 2 ) and a median of 17,032 bacterial 16S rRNA gene copies per phone. Potentially pathogenic microbes ( Staphylococcus aureus , Acinetobacter spp. , Pseudomonas spp., Bacillus cereus and Neisseria flavescens ) were found among dominant microbes more often on phones with higher percentage of E. faecalis in total bacterial 16S rRNA. No differences in contamination level or dominating bacterial species between phone owner's gender and between phone types (touch screen/keypad) were found. No antibiotic resistance genes were detected on mobile phone surfaces. Quantitative study methods revealed high level bacterial contamination of secondary school students' mobile phones.

Confirmation of RAX gene involvement in human anophthalmia

PubMed Central

Lequeux, L.; Rio, Marlène; Vigouroux, Armelle; Titeux, Matthias; Etchevers, Heather; Malecaze, François; Chassaing, Nicolas; Calvas, Patrick

2008-01-01

Microphthalmia and anophthalmia are at the severe end of the spectrum of abnormalities in ocular development. Mutations in several genes have been involved in syndromic and non-syndromic anophthalmia. Previously, RAX recessive mutations were implicated in a single patient with right anophthalmia and left microphthalmia and sclerocornea. Here, we report the findings of novel compound heterozygous RAX mutations in a child with bilateral anophthalmia. Both mutations are located in exon 3. c.664delT is a frameshifting deletion predicted to introduce a premature stop codon (p.Ser222ArgfsX62), and c.909 C>G is a nonsense mutation with similar consequences (p.Tyr303X). This is the second report of a patient with anophthalmia caused by RAX mutations. These findings confirm that RAX plays a major role in the early stages of eye development and is involved in human anophthalmia. PMID:18783408

Confirmation of RAX gene involvement in human anophthalmia.

PubMed

Lequeux, L; Rio, M; Vigouroux, A; Titeux, M; Etchevers, H; Malecaze, F; Chassaing, N; Calvas, P

2008-10-01

Microphthalmia and anophthalmia are at the severe end of the spectrum of abnormalities in ocular development. Mutations in several genes have been involved in syndromic and non-syndromic anophthalmia. Previously, RAX recessive mutations were implicated in a single patient with right anophthalmia, left microphthalmia and sclerocornea. In this study, we report the findings of novel compound heterozygous RAX mutations in a child with bilateral anophthalmia. Both mutations are located in exon 3. c.664delT is a frameshifting deletion predicted to introduce a premature stop codon (p.Ser222ArgfsX62), and c.909C>G is a nonsense mutation with similar consequences (p.Tyr303X). This is the second report of a patient with anophthalmia caused by RAX mutations. These findings confirm that RAX plays a major role in the early stages of eye development and is involved in human anophthalmia.

Metatranscriptome Analysis of the Vaginal Microbiota Reveals Potential Mechanisms for Protection against Metronidazole in Bacterial Vaginosis.

PubMed

Deng, Zhi-Luo; Gottschick, Cornelia; Bhuju, Sabin; Masur, Clarissa; Abels, Christoph; Wagner-Döbler, Irene

2018-06-27

Bacterial vaginosis (BV) is a prevalent multifactorial disease of women in their reproductive years characterized by a shift from the Lactobacillus species-dominated microbial community toward a taxonomically diverse anaerobic community. For unknown reasons, some women do not respond to therapy. In our recent clinical study, among 37 women diagnosed with BV, 31 were successfully treated with metronidazole, while 6 still had BV after treatment. To discover possible reasons for the lack of response in those patients, we performed a metatranscriptome analysis of their vaginal microbiota, comparing them to the patients who responded. Seven of 8 clustered regularly interspaced short palindromic repeat (CRISPR)-associated (Cas) genes of Gardnerella vaginalis were highly upregulated in nonresponding patients. Cas genes, in addition to protecting against phages, might be involved in DNA repair, thus mitigating the bactericidal effect of DNA-damaging agents such as metronidazole. In the second part of our study, we analyzed the vaginal metatranscriptomes of four patients over 3 months and showed high in vivo expression of genes for pore-forming toxins in L. iners and of genes encoding enzymes for the production of hydrogen peroxide and d-lactate in L. crispatus IMPORTANCE Bacterial vaginosis is a serious issue for women in their reproductive years. Although it can usually be cured by antibiotics, the recurrence rate is very high, and some women do not respond to antibiotic therapy. The reasons for that are not known. Therefore, we undertook a study to detect the activity of the complete microbiota in the vaginal fluid of women who responded to antibiotic therapy and compared it to the activity of the microbiota in women who did not respond. We found that one of the most important pathogens in bacterial vaginosis, Gardnerella vaginalis , has activated genes that can repair the DNA damage caused by the antibiotic in those women that do not respond to therapy. Suppressing

Antibiotic resistance genes and intI1 prevalence in a swine wastewater treatment plant and correlation with metal resistance, bacterial community and wastewater parameters.

PubMed

Yuan, Qing-Bin; Zhai, Yi-Fan; Mao, Bu-Yun; Hu, Nan

2018-06-07

The livestock wastewater treatment plant represents an important reservoir of antibiotic resistance determinants in the environment. The study explored the prevalence of five antibiotic resistance genes (ARGs, including sulI, tetA, qnrD, mphB and mcr-1) and class 1 integron (intI1) in a typical livestock wastewater treatment plant, and analyzed their integrated association with two metal resistance genes (copA and czcA), two pathogens genes (Staphylococcus and Campylobacter), bacterial community and wastewater properties. Results indicated that all investigated genes were detected in the plant. The treatment plant could not completely remove ARGs abundances, with up to 2.2 × 10 4 ~3.7 × 10 8 copies/L of them remaining in the effluent. Mcr-1 was further enriched by 27-fold in the subsequent pond. The correlation analysis showed that mphB significantly correlateed with tetA and intI. Mcr-1 strongly correlated with copA. MphB and intI significantly correlated with czcA. The correlations implied a potential co-selection risk of bacterial resistant to antibiotics and metals. Redundancy analyses indicated that qnrD and mcr-1 strongly correlated with 13 and 14 bacterial genera, respectively. Most ARGs positively correlated to wastewater nutrients, indicating that an efficient reduction of wastewater nutrients would contribute to the antibiotic resistance control. The study will provide useful implications on fates and reductions of ARGs in livestock facilities and receiving environments. Copyright © 2018. Published by Elsevier Inc.

Next-generation sequencing identification of pathogenic bacterial genes and their relationship with fecal indicator bacteria in different water sources in the Kathmandu Valley, Nepal.

PubMed

Ghaju Shrestha, Rajani; Tanaka, Yasuhiro; Malla, Bikash; Bhandari, Dinesh; Tandukar, Sarmila; Inoue, Daisuke; Sei, Kazunari; Sherchand, Jeevan B; Haramoto, Eiji

2017-12-01

Bacteriological analysis of drinking water leads to detection of only conventional fecal indicator bacteria. This study aimed to explore and characterize bacterial diversity, to understand the extent of pathogenic bacterial contamination, and to examine the relationship between pathogenic bacteria and fecal indicator bacteria in different water sources in the Kathmandu Valley, Nepal. Sixteen water samples were collected from shallow dug wells (n=12), a deep tube well (n=1), a spring (n=1), and rivers (n=2) in September 2014 for 16S rRNA gene next-generation sequencing. A total of 525 genera were identified, of which 81 genera were classified as possible pathogenic bacteria. Acinetobacter, Arcobacter, and Clostridium were detected with a relatively higher abundance (>0.1% of total bacterial genes) in 16, 13, and 5 of the 16 samples, respectively, and the highest abundance ratio of Acinetobacter (85.14%) was obtained in the deep tube well sample. Furthermore, the bla OXA23-like genes of Acinetobacter were detected using SYBR Green-based quantitative PCR in 13 (35%) of 37 water samples, including the 16 samples that were analyzed for next-generation sequencing, with concentrations ranging 5.3-7.5logcopies/100mL. There was no sufficient correlation found between fecal indicator bacteria, such as Escherichia coli and total coliforms, and potential pathogenic bacteria, as well as the bla OXA23-like gene of Acinetobacter. These results suggest the limitation of using conventional fecal indicator bacteria in evaluating the pathogenic bacteria contamination of different water sources in the Kathmandu Valley. Copyright © 2017 Elsevier B.V. All rights reserved.

Genes Involved in Anaerobic Metabolism of Phenol in the Bacterium Thauera aromatica

PubMed Central

Breinig, Sabine; Schiltz, Emile; Fuchs, Georg

2000-01-01

Genes involved in the anaerobic metabolism of phenol in the denitrifying bacterium Thauera aromatica have been studied. The first two committed steps in this metabolism appear to be phosphorylation of phenol to phenylphosphate by an unknown phosphoryl donor (“phenylphosphate synthase”) and subsequent carboxylation of phenylphosphate to 4-hydroxybenzoate under release of phosphate (“phenylphosphate carboxylase”). Both enzyme activities are strictly phenol induced. Two-dimensional gel electrophoresis allowed identification of several phenol-induced proteins. Based on N-terminal and internal amino acid sequences of such proteins, degenerate oligonucleotides were designed to identify the corresponding genes. A chromosomal DNA segment of about 14 kbp was sequenced which contained 10 genes transcribed in the same direction. These are organized in two adjacent gene clusters and include the genes coding for five identified phenol-induced proteins. Comparison with sequences in the databases revealed the following similarities: the gene products of two open reading frames (ORFs) are each similar to either the central part and N-terminal part of phosphoenolpyruvate synthases. We propose that these ORFs are components of the phenylphosphate synthase system. Three ORFs showed similarity to the ubiD gene product, 3-octaprenyl-4-hydroxybenzoate carboxy lyase; UbiD catalyzes the decarboxylation of a 4-hydroxybenzoate analogue in ubiquinone biosynthesis. Another ORF was similar to the ubiX gene product, an isoenzyme of UbiD. We propose that (some of) these four proteins are involved in the carboxylation of phenylphosphate. A 700-bp PCR product derived from one of these ORFs cross-hybridized with DNA from different Thauera and Azoarcus strains, even from those which have not been reported to grow with phenol. One ORF showed similarity to the mutT gene product, and three ORFs showed no strong similarities to sequences in the databases. Upstream of the first gene cluster, an

Influence of zeolite and superphosphate as additives on antibiotic resistance genes and bacterial communities during factory-scale chicken manure composting.

PubMed

Peng, Shuang; Li, Huijie; Song, Dan; Lin, Xiangui; Wang, Yiming

2018-04-30

Factory-scale chicken manure composting added with zeolite (F), superphosphate (G), or zeolite and ferrous sulfate (FL) simultaneously, were evaluate for their effects on the behaviors of antibiotic resistance genes (ARGs) and bacterial communities. After composting, ARGs in manure decreased by 67.3% in the control, whereas the reductions were 86.5%, 68.6% and 72.2% in F, G and FL, respectively. ARGs encoding ribosomal protection proteins (tetO, tetB(P), and tetM) were reduced to a greater extent than tetG, tetL, sul1 and sul2. Bacteria pathogens were also effectively removed by composting. Network analysis showed that Firmicutes were the important potential host bacteria for ARGs. The bacterial communities and environmental factors, as well as the intI gene, contributed significantly to the variation of ARGs. The ARGs and integrons were reduced more when zeolite was added than when superphosphate was added; thus, it may be useful for reducing the risks of ARGs in chicken manure. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fox (forkhead) genes are involved in the dorso-ventral patterning of the Xenopus mesoderm.

PubMed

El-Hodiri, H; Bhatia-Dey, N; Kenyon, K; Ault, K; Dirksen, M; Jamrich, M

2001-01-01

Fox (forkhead/winged helix) genes encode a family of transcription factors that are involved in embryonic pattern formation, regulation of tissue specific gene expression and tumorigenesis. Several of them are transcribed during Xenopus embryogenesis and are important for the patterning of ectoderm, mesoderm and endoderm. We have isolated three forkhead genes that are activated during gastrulation and play an important role in the dorso-ventral patterning of the mesoderm. XFKH1 (FoxA4b), the first vertebrate forkhead gene to be implicated in embryonic pattern formation, is expressed in the Spemann-Mangold organizer region and later in the embryonic notochord. XFKH7, the Xenopus orthologue of the murine Mfh1(Foxc2), is expressed in the presomitic mesoderm, but not in the notochord or lateral plate mesoderm. Finally, XFD-13'(FoxF1b)1 is expressed in the lateral plate mesoderm, but not in the notochord or presomitic mesoderm. Expression pattern and functional experiments indicate that these three forkhead genes are involved in the dorso-ventral patterning of the mesoderm.