99901
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Siddiqui AM, Haroon T, Rani M, Ansari AR. An analysis of the flow of a power law fluid due to ciliary motion in an infinite channel. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/s12573-011-0026-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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99902
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Skin microbiota: microbial community structure and its potential association with health and disease. INFECTION GENETICS AND EVOLUTION 2011; 11:839-48. [PMID: 21463709 DOI: 10.1016/j.meegid.2011.03.022] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 03/24/2011] [Accepted: 03/25/2011] [Indexed: 12/22/2022]
Abstract
Skin, the largest human organ, is a complex and dynamic ecosystem inhabited by a multitude of microorganisms. Host demographics and genetics, human behavior, local and regional environmental characteristics, and transmission events may all potentially drive human skin microbiota variability, resulting in an alteration of microbial community structure. This alteration may have important consequences regarding health and disease outcomes among individuals. More specifically, certain diversity patterns of human microbiota may be predictive or diagnostic of disease. The purpose of this review is to briefly describe the skin microbiota, outline the potential determining factors driving its variability, posit the likelihood of an association between the resulting microbial community structure on the skin with disease outcomes among individuals, and finally, to present some challenges and implications for studying the skin microbiota.
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99903
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Malla N, Kaul P, Sehgal R, Gupta I. The presence of dsRNA virus in Trichomonas vaginalis isolates from symptomatic and asymptomatic Indian women and its correlation with in vitro metronidazole sensitivity. Indian J Med Microbiol 2011; 29:152-7. [DOI: 10.4103/0255-0857.81801] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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99904
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Bacterial SOS response: a food safety perspective. Curr Opin Biotechnol 2011; 22:136-42. [DOI: 10.1016/j.copbio.2010.11.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 11/17/2010] [Accepted: 11/23/2010] [Indexed: 11/19/2022]
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99905
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Bacterial spores in food: how phenotypic variability complicates prediction of spore properties and bacterial behavior. Curr Opin Biotechnol 2011; 22:180-6. [DOI: 10.1016/j.copbio.2010.11.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 11/12/2010] [Accepted: 11/15/2010] [Indexed: 11/21/2022]
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99906
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Anti-Giardia activity of Syzygium aromaticum essential oil and eugenol: Effects on growth, viability, adherence and ultrastructure. Exp Parasitol 2011; 127:732-9. [DOI: 10.1016/j.exppara.2011.01.011] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 11/26/2010] [Accepted: 01/19/2011] [Indexed: 11/23/2022]
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99907
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Maranhão FC, Silveira HC, Rossi A, Martinez-Rossi NM. Isolation of transcripts overexpressed in the human pathogenTrichophyton rubrumgrown in lipid as carbon source. Can J Microbiol 2011; 57:333-8. [DOI: 10.1139/w11-011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Trichophyton rubrum is the most common etiological agent of human dermatophytosis. Despite the incidence and medical importance of this dermatophyte, little is known about the mechanisms of host invasion and pathogenicity. Host invasion depends on the adaptive cellular responses of the pathogen that allow it to penetrate the skin layers, which are mainly composed of proteins and lipids. In this study, we used suppression subtractive hybridization to identify transcripts overexpressed in T. rubrum cultured in lipid as carbon source. Among the subtractive cDNA clones isolated, 85 clones were positively screened by cDNA array dot blotting and were sequenced. The putative proteins encoded by the isolated transcripts showed similarities to fungal proteins involved in metabolism, signaling, defense, and virulence, such as the MDR/ABC transporter, glucan 1,3-β-glucosidase, chitin synthase B, copper-sulfate-regulated protein, and serine/threonine phosphatase (calcineurin A). These results provide the first molecular insight into the genes differentially expressed during the adaptation of T. rubrum to a lipidic carbon source.
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Affiliation(s)
- Fernanda C.A. Maranhão
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, 14049-900 Ribeirão Preto, São Paulo, Brazil
| | - Henrique C.S. Silveira
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, 14049-900 Ribeirão Preto, São Paulo, Brazil
| | - Antonio Rossi
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, 14049-900 Ribeirão Preto, São Paulo, Brazil
| | - Nilce M. Martinez-Rossi
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, 14049-900 Ribeirão Preto, São Paulo, Brazil
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99908
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Oliveira VM, Lopes-Oliveira PF, Passarini MRZ, Menezes CBA, Oliveira WRC, Rocha AJ, Sette LD. Molecular analysis of microbial diversity in corrosion samples from energy transmission towers. BIOFOULING 2011; 27:435-447. [PMID: 21563009 DOI: 10.1080/08927014.2011.581751] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Microbial diversity in corrosion samples from energy transmission towers was investigated using molecular methods. Ribosomal DNA fragments were used to assemble gene libraries. Sequence analysis indicated 10 bacterial genera within the phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. In the two libraries generated from corroded screw-derived samples, the genus Acinetobacter was the most abundant. Acinetobacter and Clostridium spp. dominated, with similar percentages, in the libraries derived from corrosion scrapings. Fungal clones were affiliated with 14 genera belonging to the phyla Ascomycota and Basidiomycota; of these, Capnobotryella and Fellomyces were the most abundant fungi observed. Several of the microorganisms had not previously been associated with biofilms and corrosion, reinforcing the need to use molecular techniques to achieve a more comprehensive assessment of microbial diversity in environmental samples.
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Affiliation(s)
- Valéria M Oliveira
- Divisão de Recursos Microbianos, CPQBA/UNICAMP, CP 6171, Campinas, Brazil.
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99909
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Jia C, Liu T, Chang AK, Zhai Y. Prediction of mitochondrial proteins of malaria parasite using bi-profile Bayes feature extraction. Biochimie 2011; 93:778-82. [DOI: 10.1016/j.biochi.2011.01.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 01/22/2011] [Indexed: 11/26/2022]
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99910
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Zhu PL, Zhao S, Tang JL, Feng JX. The rsmA-like gene rsmA(Xoo) of Xanthomonas oryzae pv. oryzae regulates bacterial virulence and production of diffusible signal factor. MOLECULAR PLANT PATHOLOGY 2011; 12:227-37. [PMID: 21355995 PMCID: PMC6640276 DOI: 10.1111/j.1364-3703.2010.00661.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The plant-pathogenic prokaryote Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight, one of the most destructive diseases of rice. A nonpolar mutant of the rsmA-like gene rsmA(Xoo) of the Xoo Chinese strain 13751 was constructed by homologous integration with a suicide plasmid. Virulence tests on a host plant, namely the hybrid rice cultivar Teyou 63, showed that the mutant had lost its virulence almost completely, whereas tests on a nonhost, namely castor-oil plant (Ricinus communis), showed that the mutant had also lost the ability to induce a hypersensitive response in the nonhost. In addition, the rsmA(Xoo) mutant produced significantly smaller amounts of the diffusible signal factor, extracellular endoglucanase, amylase and extracellular polysaccharide, but showed significantly higher glycogen accumulation, bacterial aggregation and cell adhesion. The expression of most hrp genes, genes encoding AvrBs3/PthA family members, rpfB, xrvA, glgA, eglXoB and XOO0175 (encoding an α-amylase) was down-regulated in the rsmA(Xoo) mutant. All phenotypes and expression levels of the tested genes in the rsmA(Xoo) mutant were restored to their levels in the wild-type by the presence of rsmA(Xoo) in trans. These results indicate that rsmA(Xoo) is essential for the virulence of Xoo.
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Affiliation(s)
- Pei-Liang Zhu
- Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
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99911
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Spiering MJ, Urban LA, Nuss DL, Gopalan V, Stoltzfus A, Eisenstein E. Gene identification in black cohosh (Actaea racemosa L.): expressed sequence tag profiling and genetic screening yields candidate genes for production of bioactive secondary metabolites. PLANT CELL REPORTS 2011; 30:613-629. [PMID: 21188383 DOI: 10.1007/s00299-010-0979-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 11/30/2010] [Accepted: 12/08/2010] [Indexed: 05/30/2023]
Abstract
Black cohosh (Actaea racemosa L., syn. Cimicifuga racemosa, Nutt., Ranunculaceae) is a popular herb used for relieving menopausal discomforts. A variety of secondary metabolites, including triterpenoids, phenolic dimers, and serotonin derivatives have been associated with its biological activity, but the genes and metabolic pathways as well as the tissue distribution of their production in this plant are unknown. A gene discovery effort was initiated in A. racemosa by partial sequencing of cDNA libraries constructed from young leaf, rhizome, and root tissues. In total, 2,066 expressed sequence tags (ESTs) were assembled into 1,590 unique genes (unigenes). Most of the unigenes were predicted to encode primary metabolism genes, but about 70 were identified as putative secondary metabolism genes. Several of these candidates were analyzed further and full-length cDNA and genomic sequences for a putative 2,3 oxidosqualene cyclase (CAS1) and two BAHD-type acyltransferases (ACT1 and HCT1) were obtained. Homology-based PCR screening for the central gene in plant serotonin biosynthesis, tryptophan decarboxylase (TDC), identified two TDC-related sequences in A. racemosa. CAS1, ACT1, and HCT1 were expressed in most plant tissues, whereas expression of TDC genes was detected only sporadically in immature flower heads and some very young leaf tissues. The cDNA libraries described and assorted genes identified provide initial insight into gene content and diversity in black cohosh, and provide tools and resources for detailed investigations of secondary metabolite genes and enzymes in this important medicinal plant.
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Affiliation(s)
- Martin J Spiering
- Fischell Department of Bioengineering, Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
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99912
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Coletta-Filho HD, Bittleston LS, Almeida RPP. Spatial genetic structure of a vector-borne generalist pathogen. Appl Environ Microbiol 2011; 77:2596-601. [PMID: 21317251 PMCID: PMC3126377 DOI: 10.1128/aem.02172-10] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 02/05/2011] [Indexed: 11/20/2022] Open
Abstract
Vector-borne generalist pathogens colonize several reservoir species and are usually dependent on polyphagous arthropods for dispersal; however, their spatial genetic structure is generally poorly understood. Using fast-evolving genetic markers (20 simple sequence repeat loci, resulting in a total of 119 alleles), we studied the genetic structure of the vector-borne plant-pathogenic bacterium Xylella fastidiosa in Napa Valley, CA, where it causes Pierce's disease when it is transmitted to grapevines from reservoir plants in adjacent riparian vegetation. Eighty-three different X. fastidiosa multilocus microsatellite genotypes were found in 93 isolates obtained from five vineyards, resulting in an index of clonal fraction closer to 0 and a Simpson's genotypic diversity index (D) closer to a maximum value of 1. Moderate values of Nei's gene diversity (H(Nei); average H(Nei) = 0.41) were observed for most of the X. fastidiosa populations. The low Wright's index of genetic diversity among populations calculated by the FSTAT software (Wright's F(ST) index) among population pairs (0.0096 to 0.1080) indicated a weak or absent genetic structure among the five populations; a panmictic population was inferred by Bayesian analyses (with the STRUCTURE and BAPS programs). Furthermore, a Mantel test showed no significant genetic isolation by distance when both Nei (r = -0.3459, P = 0.268) and linearized (r = -0.3106, P = 0.269) indices were used. These results suggest that the riparian vegetation from which vectors acquire the pathogen prior to inoculation of grapevines supports a diverse population of X. fastidiosa.
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Affiliation(s)
- Helvécio D. Coletta-Filho
- IAC-Centro APTA Citros Sylvio Moreira, Cordeiropolis, Sao Paulo, Brazil
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California
| | - Leonora S. Bittleston
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California
| | - Rodrigo P. P. Almeida
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California
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99913
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Luís AS, Alves VD, Romão MJ, Prates JAM, Fontes CMGA, Najmudin S. Overproduction, purification, crystallization and preliminary X-ray characterization of a novel carbohydrate-binding module of endoglucanase Cel5A from Eubacterium cellulosolvens. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:491-3. [PMID: 21505249 PMCID: PMC3080158 DOI: 10.1107/s1744309111004246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 02/03/2011] [Indexed: 05/30/2023]
Abstract
The anaerobic cellulolytic rumen bacterium Eubacterium cellulosolvens produces a large array of cellulases and hemicellulases that are responsible for the hydrolysis of plant cell-wall polysaccharides. One of these enzymes, endoglucanase Cel5A, comprises two tandemly repeated novel carbohydrate-binding modules (CBMs) and two catalytic domains belonging to glycoside hydrolase family 5 joined by flexible linker sequences. The novel CBM located at the N-terminus of the endoglucanase has been crystallized. The crystals belonged to the hexagonal space group P6(1)22 and contained a single molecule in the asymmetric unit. The structure of the L-selenomethionine derivative has been solved by a MAD experiment on crystals that diffracted to 1.75 Å resolution.
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Affiliation(s)
- Ana S. Luís
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Victor D. Alves
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Maria J. Romão
- REQUIMTE, Departamento de Química, FCT–UNL, 2829-516 Caparica, Portugal
| | - José A. M. Prates
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Carlos M. G. A. Fontes
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Shabir Najmudin
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
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99914
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Stappenbeck TS, Rioux JD, Mizoguchi A, Saitoh T, Huett A, Darfeuille-Michaud A, Wileman T, Mizushima N, Carding S, Akira S, Parkes M, Xavier RJ. Crohn disease: a current perspective on genetics, autophagy and immunity. Autophagy 2011; 7:355-74. [PMID: 20729636 PMCID: PMC3842289 DOI: 10.4161/auto.7.2.13074] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Accepted: 04/17/2010] [Indexed: 12/13/2022] Open
Abstract
Crohn disease (CD) is a chronic and debilitating inflammatory condition of the gastrointestinal tract. Prevalence in Western populations is 100-150/100,000 and somewhat higher in Ashkenazi Jews. Peak incidence is in early adult life, although any age can be affected and a majority of affected individuals progress to relapsing and chronic disease. Medical treatments rely significantly on empirical corticosteroid therapy and immunosuppression, and intestinal resectional surgery is frequently required. Thus, 80% of patients with CD come to surgery for refractory disease or complications. It is hoped that an improved understanding of pathogenic mechanisms, for example by studying the genetic basis of CD and other forms of inflammatory bowel diseases (IBD), will lead to improved therapies and possibly preventative strategies in individuals identified as being at risk.
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Affiliation(s)
- Thaddeus S. Stappenbeck
- Departments of Pathology and Immunology; Washington University School of Medicine; St. Louis, MO USA
| | - John D. Rioux
- Université de Montréal; Montréal, Québec Canada
- Montreal Heart Institute; Montréal, Québec Canada
| | - Atsushi Mizoguchi
- Center for the Study of Inflammatory Bowel Disease; Massachusetts General Hospital and Harvard Medical School; Boston, MA USA
- Department of Pathology; Massachusetts General Hospital and Harvard Medical School; Boston, MA USA
| | - Tatsuya Saitoh
- Laboratory of Host Defense; WPI Immunology Frontier Research Center; Osaka University; Suita, Osaka Japan
- Department of Host Defense Osaka; Japan
| | - Alan Huett
- Center for the Study of Inflammatory Bowel Disease; Massachusetts General Hospital and Harvard Medical School; Boston, MA USA
| | | | - Tom Wileman
- Infection and Immunity; School of Medicine; Faculty of Health; University of East Anglia; East Anglia, Norfolk UK
| | - Noboru Mizushima
- Department of Physiology and Cell Biology at Tokyo Medical and Dental University; Bunkyo-ku, Tokyo Japan
| | | | - Shizuo Akira
- Laboratory of Host Defense; WPI Immunology Frontier Research Center; Osaka University; Suita, Osaka Japan
- Department of Host Defense Osaka; Japan
| | - Miles Parkes
- IBD Research Group; Addenbrooke’s Hospital; University of Cambridge; Cambridge UK
| | - Ramnik J. Xavier
- Center for the Study of Inflammatory Bowel Disease; Massachusetts General Hospital and Harvard Medical School; Boston, MA USA
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99915
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Insight into functional diversity of cytochrome P450 in the white-rot basidiomycete Phanerochaete chrysosporium: Involvement of versatile monooxygenase. Biochem Biophys Res Commun 2011; 407:118-23. [DOI: 10.1016/j.bbrc.2011.02.121] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 02/24/2011] [Indexed: 01/25/2023]
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99916
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Liberton M, Austin JR, Berg RH, Pakrasi HB. Unique thylakoid membrane architecture of a unicellular N2-fixing cyanobacterium revealed by electron tomography. PLANT PHYSIOLOGY 2011; 155:1656-66. [PMID: 21173021 PMCID: PMC3091100 DOI: 10.1104/pp.110.165332] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.
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99917
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Bae E, Aroonnual A, Bhunia AK, Hirleman ED. On the sensitivity of forward scattering patterns from bacterial colonies to media composition. JOURNAL OF BIOPHOTONICS 2011; 4:236-243. [PMID: 20549773 DOI: 10.1002/jbio.201000051] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Morphology of colonies is important for taxonomy and diagnostics in microbiology where the response to environmental factors is sensitive enough to support discrimination. In this research, we analyzed the forward scattering patterns of individual Escherichia coli K12 colonies when agar hardness and nutrition levels were varied from the control sample. As the agar concentration increased from 1.2% to 1.8%, the diameter of the forward scattering patterns also increased for the same experimental condition which reflects that the colony thickness at the apex is greater for increased agar concentrations. Regarding nutrition, increasing dextrose resulted in smaller mean colony diameters while the mean diameters of the colonies were proportional to the yeast extract concentration up to 0.5%. The result reveals that ±0.3% agar concentration from the control sample is sufficient to create variations in the scattering patterns. For nutrition -0.25% of yeast extract showed significant variations while +0.25% from control sample showed minimal variations.
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Affiliation(s)
- Euiwon Bae
- School of Mechanical Engineering, Purdue University, IN 47907, USA.
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99918
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Coupat-Goutaland B, Bernillon D, Guidot A, Prior P, Nesme X, Bertolla F. Ralstonia solanacearum virulence increased following large interstrain gene transfers by natural transformation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:497-505. [PMID: 21190441 DOI: 10.1094/mpmi-09-10-0197] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Horizontal gene transfer (HGT) is a major driving force of evolution and is also likely to play an important role in the threatening emergence of novel pathogens, especially if it involves distantly related strains with substantially different pathogenicity. In this study, the impact of natural transformation on pathogenicity in six strains belonging to the four phylotypes of the plant-pathogenic bacterium Ralstonia solanacearum was investigated. The study focused on genomic regions that vary between donor and recipient strains and that carry genes involved in pathogenicity such as type III effectors. First, strains from R. solanacearum species complex were naturally transformed with heterologous genomic DNA. Transferred DNA regions were then determined by comparative genomic hybridization and polymerase chain reaction sequencing. We identified three transformant strains that acquired large DNA regions of up to 80 kb. In one case, strain Psi07 (phylotype IV tomato isolate) acquired 39.4 kb from GMI1000 (phylotype I tomato isolate). Investigations revealed that i) 24.4 kb of the acquired region contained 20 new genes, ii) an allelic exchange of 12 genes occurred, and iii) 27 genes (33.4 kb) formerly present in Psi07 were lost. Virulence tests with the three transformants revealed a significant increase in the aggressiveness of BCG20 over its Psi07 parent on tomato. These findings demonstrate the potential importance of HGT in the pathogenic evolution of R. solanacearum strains and open new avenues for studying pathogen emergence.
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Affiliation(s)
- Bénédicte Coupat-Goutaland
- Université de Lyon, Université Lyon 1, CNRS, INRA, 16 rue Raphaël Dubois, Domaine Scientifique de La Doua, 69622 Villeurbanne cedex, France
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99919
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Volokhov DV, Graham LJ, Brorson KA, Chizhikov VE. Mycoplasma testing of cell substrates and biologics: Review of alternative non-microbiological techniques. Mol Cell Probes 2011; 25:69-77. [DOI: 10.1016/j.mcp.2011.01.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 12/22/2010] [Accepted: 01/04/2011] [Indexed: 11/25/2022]
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99920
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Daugeron MC, Lenstra TL, Frizzarin M, El Yacoubi B, Liu X, Baudin-Baillieu A, Lijnzaad P, Decourty L, Saveanu C, Jacquier A, Holstege FCP, de Crécy-Lagard V, van Tilbeurgh H, Libri D. Gcn4 misregulation reveals a direct role for the evolutionary conserved EKC/KEOPS in the t6A modification of tRNAs. Nucleic Acids Res 2011; 39:6148-60. [PMID: 21459853 PMCID: PMC3152333 DOI: 10.1093/nar/gkr178] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The EKC/KEOPS complex is universally conserved in Archaea and Eukarya and has been implicated in several cellular processes, including transcription, telomere homeostasis and genomic instability. However, the molecular function of the complex has remained elusive so far. We analyzed the transcriptome of EKC/KEOPS mutants and observed a specific profile that is highly enriched in targets of the Gcn4p transcriptional activator. GCN4 expression was found to be activated at the translational level in mutants via the defective recognition of the inhibitory upstream ORFs (uORFs) present in its leader. We show that EKC/KEOPS mutants are defective for the N6-threonylcarbamoyl adenosine modification at position 37 (t6A37) of tRNAs decoding ANN codons, which affects initiation at the inhibitory uORFs and provokes Gcn4 de-repression. Structural modeling reveals similarities between Kae1 and bacterial enzymes involved in carbamoylation reactions analogous to t6A37 formation, supporting a direct role for the EKC in tRNA modification. These findings are further supported by strong genetic interactions of EKC mutants with a translation initiation factor and with threonine biosynthesis genes. Overall, our data provide a novel twist to understanding the primary function of the EKC/KEOPS and its impact on several essential cellular functions like transcription and telomere homeostasis.
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Affiliation(s)
- Marie-Claire Daugeron
- LEA Laboratory of Nuclear RNA metabolism, Centre de Génétique Moléculaire, CNRS-FRE3144, 1 av de la Terrasse, 91190 Gif sur Yvette, France
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99921
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Microbes in high arctic snow and implications for the cold biosphere. Appl Environ Microbiol 2011; 77:3234-43. [PMID: 21460114 DOI: 10.1128/aem.02611-10] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We applied molecular, microscopic, and culture techniques to characterize the microbial communities in snow and air at remote sites in the Canadian High Arctic (Ward Hunt Island, Ellesmere Island, and Cornwallis Island, latitudes 74 to 83(o)N). Members of the Bacteria and Eukarya were prevalent in the snow, and their small subunit (SSU) rRNA gene signatures indicated strong local aerial transport within the region over the preceding 8 months of winter snowpack accumulation. Many of the operational taxonomic units (OTUs) were similar to previously reported SSU rRNA gene sequences from the Arctic Ocean, suggesting the importance of local aerial transport processes for marine microbiota. More than 47% of the cyanobacterial OTUs in the snow have been previously found in microbial mats in the region, indicating that this group was also substantially derived from local sources. Viable cyanobacteria isolated from the snow indicated free exchange between the snow and adjacent mat communities. Other sequences were most similar to those found outside the Canadian Arctic but were from snow, lake and sea ice, glaciers and permafrost, alpine regions, Antarctica, and other regions of the Arctic, supporting the concept of global distribution of microbial ecotypes throughout the cold biosphere.
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99922
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Vaněk O, Brynda J, Hofbauerová K, Kukačka Z, Pachl P, Bezouška K, Řezáčová P. Crystallization and diffraction analysis of β-N-acetylhexosaminidase from Aspergillus oryzae. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:498-503. [PMID: 21505251 PMCID: PMC3080160 DOI: 10.1107/s1744309111004945] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 02/09/2011] [Indexed: 11/10/2022]
Abstract
Fungal β-N-acetylhexosaminidases are enzymes that are used in the chemoenzymatic synthesis of biologically interesting oligosaccharides. The enzyme from Aspergillus oryzae was produced and purified from its natural source and crystallized using the hanging-drop vapour-diffusion method. Diffraction data from two crystal forms (primitive monoclinic and primitive tetragonal) were collected to resolutions of 3.2 and 2.4 Å, respectively. Electrophoretic and quantitative N-terminal protein-sequencing analyses confirmed that the crystals are formed by a complete biologically active enzyme consisting of a glycosylated catalytic unit and a noncovalently attached propeptide.
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Affiliation(s)
- Ondřej Vaněk
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 12840 Prague, Czech Republic
| | - Jiří Brynda
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16610 Prague, Czech Republic
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague, Czech Republic
| | - Kateřina Hofbauerová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague, Czech Republic
| | - Zdeněk Kukačka
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 12840 Prague, Czech Republic
| | - Petr Pachl
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague, Czech Republic
| | - Karel Bezouška
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 12840 Prague, Czech Republic
| | - Pavlína Řezáčová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16610 Prague, Czech Republic
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague, Czech Republic
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99923
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Yan Q, Wang N. The ColR/ColS two-component system plays multiple roles in the pathogenicity of the citrus canker pathogen Xanthomonas citri subsp. citri. J Bacteriol 2011; 193:1590-9. [PMID: 21257774 PMCID: PMC3067642 DOI: 10.1128/jb.01415-10] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 01/10/2011] [Indexed: 01/09/2023] Open
Abstract
Bacterial citrus canker disease, which is caused by Xanthomonas citri subsp. citri, is one of the most devastating diseases of citrus plants. In this study, we characterized the role of the two-component regulatory system ColR/ColS in the pathogenicity of X. citri subsp. citri. colS mutants (256A10 and 421E7), colR mutants (386C6 and 417E10), and a colR colS double mutant (306DSR) all lost pathogenicity and produced no symptoms on grapefruit leaves inoculated by either pressure infiltration or the spray method. The pathogenicity defect of the colS, colR, and colR colS mutants could be complemented using the wild-type colS, colR, and colR colS genes, respectively. Mutation of colS or colR significantly reduced X. citri subsp. citri growth in planta. The ColR/ColS system also played important roles in bacterial biofilm formation in glass tubes and on leaf surfaces, lipopolysaccharide (LPS) production, catalase activity, and tolerance of environmental stress, including phenol, copper, and hydrogen peroxide. Furthermore, quantitative reverse transcription-PCR assays demonstrated that the ColR/ColS system positively regulated the expression of important virulence genes, including hrpD6, hpaF, the O-antigen LPS synthesis gene rfbC, and the catalase gene katE. Overall, our data indicate that the two-component regulatory system ColR/ColS is critical for X. citri subsp. citri virulence, growth in planta, biofilm formation, catalase activity, LPS production, and resistance to environmental stress.
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Affiliation(s)
- Qing Yan
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850
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99924
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Wargo AR, Kurath G. In vivo fitness associated with high virulence in a vertebrate virus is a complex trait regulated by host entry, replication, and shedding. J Virol 2011; 85:3959-67. [PMID: 21307204 PMCID: PMC3126118 DOI: 10.1128/jvi.01891-10] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 01/29/2011] [Indexed: 12/14/2022] Open
Abstract
The relationship between pathogen fitness and virulence is typically examined by quantifying only one or two pathogen fitness traits. More specifically, it is regularly assumed that within-host replication, as a precursor to transmission, is the driving force behind virulence. In reality, many traits contribute to pathogen fitness, and each trait could drive the evolution of virulence in different ways. Here, we independently quantified four viral infection cycle traits, namely, host entry, within-host replication, within-host coinfection fitness, and shedding, in vivo, in the vertebrate virus Infectious hematopoietic necrosis virus (IHNV). We examined how each of these stages of the viral infection cycle contributes to the fitness of IHNV genotypes that differ in virulence in rainbow trout. This enabled us to determine how infection cycle fitness traits are independently associated with virulence. We found that viral fitness was independently regulated by each of the traits examined, with the largest impact on fitness being provided by within-host replication. Furthermore, the more virulent of the two genotypes of IHNV we used had advantages in all of the traits quantified. Our results are thus congruent with the assumption that virulence and within-host replication are correlated but suggest that infection cycle fitness is complex and that replication is not the only trait associated with virulence.
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Affiliation(s)
- Andrew R Wargo
- Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA 98115-5016, USA.
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99925
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Otto M. Panton-Valentine leukocidin antibodies for the treatment of MRSA skin infections? Expert Rev Anti Infect Ther 2011; 9:389-92. [PMID: 21504395 PMCID: PMC3106302 DOI: 10.1586/eri.11.19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) has recently caused epidemic outbreaks of community-associated (CA) skin infections. The infecting strains frequently contain the genes encoding the staphylococcal toxin, Panton-Valentine leukocidin (PVL). On that ground, the use of PVL-based vaccines has been proposed for the treatment of CA-MRSA infections, despite experimental and epidemiological evidence that does not support a major role of the PVL toxin in CA-MRSA skin disease. Hermos et al. show that antibodies to PVL do not protect from CA-MRSA skin infections in children, strongly suggesting that PVL-based immunization is of little benefit for this most frequent disease caused by CA-MRSA.
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Affiliation(s)
- Michael Otto
- Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Bethesda, MD 20892, USA.
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99926
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Traba J, Satrústegui J, del Arco A. Adenine nucleotide transporters in organelles: novel genes and functions. Cell Mol Life Sci 2011; 68:1183-206. [PMID: 21207102 PMCID: PMC11114886 DOI: 10.1007/s00018-010-0612-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 11/16/2010] [Accepted: 12/09/2010] [Indexed: 10/18/2022]
Abstract
In eukaryotes, cellular energy in the form of ATP is produced in the cytosol via glycolysis or in the mitochondria via oxidative phosphorylation and, in photosynthetic organisms, in the chloroplast via photophosphorylation. Transport of adenine nucleotides among cell compartments is essential and is performed mainly by members of the mitochondrial carrier family, among which the ADP/ATP carriers are the best known. This work reviews the carriers that transport adenine nucleotides into the organelles of eukaryotic cells together with their possible functions. We focus on novel mechanisms of adenine nucleotide transport, including mitochondrial carriers found in organelles such as peroxisomes, plastids, or endoplasmic reticulum and also mitochondrial carriers found in the mitochondrial remnants of many eukaryotic parasites of interest. The extensive repertoire of adenine nucleotide carriers highlights an amazing variety of new possible functions of adenine nucleotide transport across eukaryotic organelles.
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Affiliation(s)
- Javier Traba
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa UAM-CSIC, CIBER de Enfermedades Raras, Universidad Autónoma de Madrid, Madrid, Spain.
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99927
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Abstract
The skin is the human body's largest organ, colonized by a diverse milieu of microorganisms, most of which are harmless or even beneficial to their host. Colonization is driven by the ecology of the skin surface, which is highly variable depending on topographical location, endogenous host factors and exogenous environmental factors. The cutaneous innate and adaptive immune responses can modulate the skin microbiota, but the microbiota also functions in educating the immune system. The development of molecular methods to identify microorganisms has led to an emerging view of the resident skin bacteria as highly diverse and variable. An enhanced understanding of the skin microbiome is necessary to gain insight into microbial involvement in human skin disorders and to enable novel promicrobial and antimicrobial therapeutic approaches for their treatment.
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Affiliation(s)
- Elizabeth A Grice
- Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892-4442, USA
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99928
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Cusano AM, Burlinson P, Deveau A, Vion P, Uroz S, Preston GM, Frey-Klett P. Pseudomonas fluorescens BBc6R8 type III secretion mutants no longer promote ectomycorrhizal symbiosis. ENVIRONMENTAL MICROBIOLOGY REPORTS 2011; 3:203-210. [PMID: 23761252 DOI: 10.1111/j.1758-2229.2010.00209.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The Mycorrhiza Helper Bacterium (MHB) Pseudomonas fluorescens BBc6R8 promotes the ectomycorrhizal symbiosis between Douglas fir roots and Laccaria bicolor. In this study, we identified a non-flagellar type III secretion system (T3SS) in the draft genome of BBc6R8 similar to that described in the biocontrol strain P. fluorescens SBW25. We examined whether this T3SS plays a role in the BBc6R8 mycorrhizal helper effect by creating a deletion in the rscRST genes encoding the central channel of the injectisome. The in vitro effect of BBc6R8 T3SS mutants on the radial growth rate of L. bicolor was unchanged compared with the parental strain. In contrast, T3SS mutants were unable to promote mycorrhization, suggesting that type III secretion plays an important role in the mycorrhizal helper effect of P. fluorescens BBc6R8 independent of the promotion of hyphal growth that BBc6R8 exhibits in vitro.
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Affiliation(s)
- Angela M Cusano
- INRA, UMR1136 INRA-Nancy Université, «Interactions Arbres/Micro-organismes», Centre de Nancy, IFR110, 54280 Champenoux, France. Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK. Department of Microbiology and Immunology, Dartmouth Medical School, 208 Vail Building, Hanover, NH 03755, USA
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99929
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Filipowicz M. Prognostic potential of hepatic miR-122 measurements and antisense strategies targeting miR-122 as a therapeutic approach in viral hepatitis. Liver Int 2011; 31:437-9. [PMID: 21382154 DOI: 10.1111/j.1478-3231.2011.02476.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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99930
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Synthetic inter-species cooperation of host and virus for targeted genetic evolution. J Biotechnol 2011; 153:35-41. [DOI: 10.1016/j.jbiotec.2011.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 02/11/2011] [Accepted: 03/01/2011] [Indexed: 11/18/2022]
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99931
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Biosynthesis of complex iron–sulfur enzymes. Curr Opin Chem Biol 2011; 15:319-27. [DOI: 10.1016/j.cbpa.2011.02.012] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 01/31/2011] [Accepted: 02/10/2011] [Indexed: 11/21/2022]
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99932
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Acetogens and acetoclastic methanosarcinales govern methane formation in abandoned coal mines. Appl Environ Microbiol 2011; 77:3749-56. [PMID: 21460109 DOI: 10.1128/aem.02818-10] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In abandoned coal mines, methanogenic archaea are responsible for the production of substantial amounts of methane. The present study aimed to directly unravel the active methanogens mediating methane release as well as active bacteria potentially involved in the trophic network. Therefore, the stable-isotope-labeled precursors of methane, [(13)C]acetate and H(2)-(13)CO(2), were fed to liquid cultures from hard coal and mine timber from a coal mine in Germany. Guided by methane production rates, samples for DNA stable-isotope probing (SIP) with subsequent quantitative PCR and denaturing gradient gel electrophoretic (DGGE) analyses were taken over 6 months. Surprisingly, the formation of [(13)C]methane was linked to acetoclastic methanogenesis in both the [(13)C]acetate- and the H(2)-(13)CO(2)-amended cultures of coal and timber. H(2)-(13)CO(2) was used mainly by acetogens related to Pelobacter acetylenicus and Clostridium species. Active methanogens, closely affiliated with Methanosarcina barkeri, utilized the readily available acetate rather than the thermodynamically more favorable hydrogen. Thus, the methanogenic microbial community appears to be highly adapted to the low-H(2) conditions found in coal mines.
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99933
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Use of 1H nuclear magnetic resonance to measure intracellular metabolite levels during growth and asexual sporulation in Neurospora crassa. EUKARYOTIC CELL 2011; 10:820-31. [PMID: 21460191 DOI: 10.1128/ec.00231-10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Conidiation is an asexual sporulation pathway that is a response to adverse conditions and is the main mode of dispersal utilized by filamentous fungal pathogens for reestablishment in a more favorable environment. Heterotrimeric G proteins (consisting of α, β, and γ subunits) have been shown to regulate conidiation in diverse fungi. Previous work has demonstrated that all three of the Gα subunits in the filamentous fungus Neurospora crassa affect the accumulation of mass on poor carbon sources and that loss of gna-3 leads to the most dramatic effects on conidiation. In this study, we used (1)H nuclear magnetic resonance (NMR) to profile the metabolome of N. crassa in extracts isolated from vegetative hyphae and conidia from cultures grown under conditions of high or low sucrose. We compared wild-type and Δgna-3 strains to determine whether lack of gna-3 causes a significant difference in the global metabolite profile. The results demonstrate that the global metabolome of wild-type hyphae is influenced by carbon availability. The metabolome of the Δgna-3 strain cultured on both high and low sucrose is similar to that of the wild type grown on high sucrose, suggesting an overall defect in nutrient sensing in the mutant. However, analysis of individual metabolites revealed differences in wild-type and Δgna-3 strains cultured under conditions of low and high sucrose.
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99934
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Intramolecular isopeptide bonds: protein crosslinks built for stress? Trends Biochem Sci 2011; 36:229-37. [DOI: 10.1016/j.tibs.2010.09.007] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 09/27/2010] [Accepted: 09/29/2010] [Indexed: 01/19/2023]
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99935
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Yin XX, Zhang YY, Yang J, Zhu YG. Rapid biotransformation of arsenic by a model protozoan Tetrahymena pyriformis GL-C. [corrected]. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2011; 159:837-840. [PMID: 21277055 DOI: 10.1016/j.envpol.2010.12.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 12/22/2010] [Accepted: 12/23/2010] [Indexed: 05/30/2023]
Abstract
Arsenic biomethylation and biovolatilization are thought to be two important metabolic pathways in aquatic and soil environments. Tetrahymena thermophila is a genus of free-living ciliated protozoan that is widely distributed in freshwater environments around the world. In this study, we studied arsenic accumulation, speciation, efflux, methylation and volatilization in this unicellular eukaryote exposed to various concentrations of arsenate. Our results show that T. thermophila accumulated 187 mg.kg⁻¹ dry weight of arsenic when exposed to 40 μM for 48 h, with MMAs(V) (monomethylarsenate) and DMAs(V) (dimethylarsenate) as the dominant species, accounting for 66% of the total arsenic. Meanwhile, arsenate, arsenite, MMAs(V) and DMAs(V) were detected in the culture medium; the last three were released by the cells. The production of volatile arsenic increased with increasing external As(V) concentrations and exposure time. To our knowledge, this is the first study on arsenic metabolism, particularly biomethylation and biovolatilization, in protozoa.
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Affiliation(s)
- Xi-Xiang Yin
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
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99936
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Anbutsu H, Fukatsu T. Spiroplasma as a model insect endosymbiont. ENVIRONMENTAL MICROBIOLOGY REPORTS 2011; 3:144-53. [PMID: 23761245 DOI: 10.1111/j.1758-2229.2010.00240.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Members of the genus Spiroplasma are actively motile and helical bacteria of the class Mollicutes, which are associated with a variety of arthropods and plants. Some spiroplasmas cause female-biased sex ratios of their host insects as a result of selective death of the male offspring during embryogenesis. Several strains of male-killing spiroplasmas have been successfully transfected into Drosophila melanogaster by haemolymph injection and maintained in laboratory fly stocks. Spiroplasma-Drosophila endosymbiosis represents an ideal model system for analysing the molecular mechanisms underlying host-symbiont interactions. The infection dynamics exhibited by the symbiont within the host, the effects of external and environmental factors on the symbiotic association and symbiont interactions with the host's immune system have been investigated using this system. Comparisons between a male-killing Spiroplasma strain and its non-male-killing variant revealed that, in addition to different male-killing abilities, they also differed in infection dynamics and resistance to host innate immunity. It is currently unclear whether these different phenotypes are interconnected to each other. However, if so, such pleiotropy could facilitate our understanding of the genetic and molecular mechanisms of the endosymbiotic system.
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Affiliation(s)
- Hisashi Anbutsu
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan
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99937
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Kadioglu A, De Filippo K, Bangert M, Fernandes VE, Richards L, Jones K, Andrew PW, Hogg N. The integrins Mac-1 and alpha4beta1 perform crucial roles in neutrophil and T cell recruitment to lungs during Streptococcus pneumoniae infection. THE JOURNAL OF IMMUNOLOGY 2011; 186:5907-15. [PMID: 21460207 DOI: 10.4049/jimmunol.1001533] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Neutrophils and T cells play an important role in host protection against pulmonary infection caused by Streptococcus pneumoniae. However, the role of the integrins in recruitment of these cells to infected lungs is not well understood. In this study we used the twin approaches of mAb blockade and gene-deficient mice to investigate the relative impact of specific integrins on cellular recruitment and bacterial loads following pneumococcal infection. We find that both Mac-1 (CD11b/CD18) and α(4)β(1) (CD49d/CD29) integrins, but surprisingly not LFA-1 (CD11a/CD18), contribute to two aspects of the response. In terms of recruitment from the circulation into lungs, neutrophils depend on Mac-1 and α(4)β(1), whereas the T cells are entirely dependent on α(4)β(1). Second, immunohistochemistry results indicate that adhesion also plays a role within infected lung tissue itself. There is widespread expression of ICAM-1 within lung tissue. Use of ICAM-1(-/-) mice revealed that neutrophils make use of this Mac-1 ligand, not for lung entry or for migration within lung tissue, but for combating the pneumococcal infection. In contrast to ICAM-1, there is restricted and constitutive expression of the α(4)β(1) ligand, VCAM-1, on the bronchioles, allowing direct access of the leukocytes to the airways via this integrin at an early stage of pneumococcal infection. Therefore, integrins Mac-1 and α(4)β(1) have a pivotal role in prevention of pneumococcal outgrowth during disease both in regulating neutrophil and T cell recruitment into infected lungs and by influencing their behavior within the lung tissue itself.
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Affiliation(s)
- Aras Kadioglu
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester LE1 9HN, United Kingdom.
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99938
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Simões LC, Lemos M, Pereira AM, Abreu AC, Saavedra MJ, Simões M. Persister cells in a biofilm treated with a biocide. BIOFOULING 2011; 27:403-11. [PMID: 21547756 DOI: 10.1080/08927014.2011.579599] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
This study investigated the physiology and behaviour following treatment with ortho-phthalaldehyde (OPA), of Pseudomonas fluorescens in both the planktonic and sessile states. Steady-state biofilms and planktonic cells were collected from a bioreactor and their extracellular polymeric substances (EPS) were extracted using a method that did not destroy the cells. Cell structure and physiology after EPS extraction were compared in terms of respiratory activity, morphology, cell protein and polysaccharide content, and expression of the outer membrane proteins (OMP). Significant differences were found between the physiological parameters analysed. Planktonic cells were more metabolically active, and contained greater amounts of proteins and polysaccharides than biofilm cells. Moreover, biofilm formation promoted the expression of distinct OMP. Additional experiments were performed with cells after EPS extraction in order to compare the susceptibility of planktonic and biofilm cells to OPA. Cells were completely inactivated after exposure to the biocide (minimum bactericidal concentration, MBC = 0.55 ± 0.20 mM for planktonic cells; MBC = 1.7 ± 0.30 mM for biofilm cells). After treatment, the potential of inactivated cells to recover from antimicrobial exposure was evaluated over time. Planktonic cells remained inactive over 48 h while cells from biofilms recovered 24 h after exposure to OPA, and the number of viable and culturable cells increased over time. The MBC of the recovered biofilm cells after a second exposure to OPA was 0.58 ± 0.40 mM, a concentration similar to the MBC of planktonic cells. This study demonstrates that persister cells may survive in biocide-treated biofilms, even in the absence of EPS.
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Affiliation(s)
- Lúcia C Simões
- IBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, Portugal
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99939
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Sharma P, Gaur RK, Ikegami M. Subcellular localization of V2 protein of Tomato leaf curl Java virus by using green fluorescent protein and yeast hybrid system. PROTOPLASMA 2011; 248:281-8. [PMID: 20549267 DOI: 10.1007/s00709-010-0166-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2010] [Accepted: 05/20/2010] [Indexed: 05/29/2023]
Abstract
Tomato leaf curl Java virus-A (ToLCJV-A[ID]) from Southeast Asia is a new member of the emerging group of monopartite begomoviruses that require a betasatellite component for symptom induction. Previously, we have elucidated the role of V1 ORF encoded by ToLCJV-A[ID] in cell-to-cell movement. In this study, the role of V2 (PreCP) in localization was determined. Subcellular localization of ToLCJV-A[ID] V2 in plant tissues showed that this protein is co-localized to the cell cytoplasm, perinuclear and associated with the endoplasmic reticulum network. The results obtained from deletion analysis indicate that fusion of N-terminal part of the V2, containing the nuclear export signals (NES), directed the accumulation of fluorescence towards the cell cytoplasm. Furthermore, functionality of the NES ((20)LAVKYLQLV(29)) in the N-terminal part of the V2 protein was confirmed by one-hybrid yeast system. Taken together, these results suggest that V2 enhances the coat protein-mediated nuclear export of ToLCJV-A[ID] and is consistent with the model in which V2 mediates viral DNA export from the nucleus to the plasmodesmata.
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Affiliation(s)
- Pradeep Sharma
- Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
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99940
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Blana VA, Doulgeraki AI, Nychas GJE. Autoinducer-2-like activity in lactic acid bacteria isolated from minced beef packaged under modified atmospheres. J Food Prot 2011; 74:631-5. [PMID: 21477479 DOI: 10.4315/0362-028x.jfp-10-276] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fifteen fingerprints (assigned to Leuconostoc spp., Leuconostoc mesenteroides, Weissella viridescens, Leuconostoc citreum, and Lactobacillus sakei) of 89 lactic acid bacteria (LAB) isolated from minced beef stored under modified atmospheres at various temperatures were screened for their ability to exhibit autoinducer-2 (AI-2)-like activity under certain growth conditions. Cellfree meat extracts (CFME) were collected at the same time as the LAB isolates and tested for the presence of AI-2-like molecules. All bioassays were conducted using the Vibrio harveyi BAA-1117 (sensor 1(-), sensor 2(+)) biosensor strain. The possible inhibitory effect of meat extracts on the activity of the biosensor strain was also evaluated. AI-2-like activity was observed for Leuconostoc spp. isolates, but none of the L. sakei strains produced detectable AI-2-like activity. The AI-2-like activity was evident mainly associated with the Leuconostoc sp. B 233 strain, which was the dominant isolate recovered from storage at 10 and 15°C and at the initial and middle stages of storage at chill temperatures (0 and 5°C). The tested CFME samples displayed low AI-2-like activity and inhibited AI-2 activity regardless of the indigenous bacterial populations. The LAB isolated during meat spoilage exhibited AI-2-like activity, whereas the LAB strains retrieved depended on storage time and temperature. The production of AI-2-like molecules may affect the dominance of different bacterial strains during storage. The results provide a basis for further research concerning the effect of storage temperature on the expression of genes encoding AI-2 activity and on the diversity of the ephemeral bacterial population.
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Affiliation(s)
- Vasiliki A Blana
- Laboratory of Microbiology and Biotechnology of Foods, Department of Food Science, Technology and Human Nutrition, Agricultural University of Athens, Iera Odos 75, Athens 11855, Greece
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99941
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Mella-Herrera RA, Neunuebel MR, Kumar K, Saha SK, Golden JW. The sigE gene is required for normal expression of heterocyst-specific genes in Anabaena sp. strain PCC 7120. J Bacteriol 2011; 193:1823-32. [PMID: 21317330 PMCID: PMC3133031 DOI: 10.1128/jb.01472-10] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 01/31/2011] [Indexed: 11/20/2022] Open
Abstract
The filamentous cyanobacterium Anabaena (Nostoc) sp. strain PCC 7120 produces specialized cells for nitrogen fixation called heterocysts. Previous work showed that the group 2 sigma factor sigE (alr4249; previously called sigF) is upregulated in differentiating heterocysts 16 h after nitrogen step-down. We now show that the sigE gene is required for normal heterocyst development and normal expression levels of several heterocyst-specific genes. Mobility shift assays showed that the transcription factor NtcA binds to sites in the upstream region of sigE and that this binding is enhanced by 2-oxoglutarate (2-OG). Deletions of the region containing the NtcA binding sites in P(sigE)-gfp reporter plasmids showed that the sites contribute to normal developmental regulation but are not essential for upregulation in heterocysts. Northern RNA blot analysis of nifH mRNA revealed delayed and reduced transcript levels during heterocyst differentiation in a sigE mutant background. Quantitative reverse transcription-PCR (qRT-PCR) analyses of the sigE mutant showed lower levels of transcripts for nifH, fdxH, and hglE2 but normal levels for hupL. We developed a P(nifHD)-gfp reporter construct that showed strong heterocyst-specific expression. Time-lapse microscopy of the P(nifHD)-gfp reporter in a sigE mutant background showed delayed development and undetectable green fluorescent protein (GFP) fluorescence. Overexpression of sigE caused accelerated heterocyst development, an increased heterocyst frequency, and premature expression of GFP fluorescence from the P(nifHD)-gfp reporter.
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Affiliation(s)
- Rodrigo A. Mella-Herrera
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
- Division of Biological Sciences, University of California—San Diego, La Jolla, California 92093-0116
| | - M. Ramona Neunuebel
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
| | - Krithika Kumar
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
| | - Sushanta K. Saha
- Division of Biological Sciences, University of California—San Diego, La Jolla, California 92093-0116
| | - James W. Golden
- Division of Biological Sciences, University of California—San Diego, La Jolla, California 92093-0116
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99942
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Ramsey ME, Woodhams KL, Dillard JP. The Gonococcal Genetic Island and Type IV Secretion in the Pathogenic Neisseria. Front Microbiol 2011; 2:61. [PMID: 21833316 PMCID: PMC3153036 DOI: 10.3389/fmicb.2011.00061] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 03/21/2011] [Indexed: 01/10/2023] Open
Abstract
Eighty percent of Neisseria gonorrhoeae strains and some Neisseria meningitidis strains encode a 57-kb gonococcal genetic island (GGI). The GGI was horizontally acquired and is inserted in the chromosome at the replication terminus. The GGI is flanked by direct repeats, and site-specific recombination at these sites results in excision of the GGI and may be responsible for its original acquisition. Although the role of the GGI in N. meningitidis is unclear, the GGI in N. gonorrhoeae encodes a type IV secretion system (T4SS). T4SS are versatile multi-protein complexes and include both conjugation systems as well as effector systems that translocate either proteins or DNA-protein complexes. In N. gonorrhoeae, the T4SS secretes single-stranded chromosomal DNA into the extracellular milieu in a contact-independent manner. Importantly, the DNA secreted through the T4SS is effective in natural transformation and therefore contributes to the spread of genetic information through Neisseria populations. Mutagenesis experiments have identified genes for DNA secretion including those encoding putative structural components of the apparatus, peptidoglycanases which may act in assembly, and relaxosome components for processing the DNA and delivering it to the apparatus. The T4SS may also play a role in infection by N. gonorrhoeae. During intracellular infection, N. gonorrhoeae requires the Ton complex for iron acquisition and survival. However, N. gonorrhoeae strains that do not express the Ton complex can survive intracellularly if they express structural components of the T4SS. These data provide evidence that the T4SS is expressed during intracellular infection and suggest that the T4SS may provide an advantage for intracellular survival. Here we review our current understanding of how the GGI and type IV secretion affect natural transformation and pathogenesis in N. gonorrhoeae and N. meningitidis.
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Affiliation(s)
- Meghan E. Ramsey
- Department of Medical Microbiology and Immunology, University of Wisconsin-MadisonMadison, WI, USA
| | - Katelynn L. Woodhams
- Department of Medical Microbiology and Immunology, University of Wisconsin-MadisonMadison, WI, USA
| | - Joseph P. Dillard
- Department of Medical Microbiology and Immunology, University of Wisconsin-MadisonMadison, WI, USA
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99943
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Gamage AM, Shui G, Wenk MR, Chua KL. N-Octanoylhomoserine lactone signalling mediated by the BpsI–BpsR quorum sensing system plays a major role in biofilm formation of Burkholderia pseudomallei. Microbiology (Reading) 2011; 157:1176-1186. [DOI: 10.1099/mic.0.046540-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The genome of Burkholderia pseudomallei encodes three acylhomoserine lactone (AHL) quorum sensing systems, each comprising an AHL synthase and a signal receptor/regulator. The BpsI–BpsR system produces N-octanoylhomoserine lactone (C8HL) and is positively auto-regulated by its AHL product. The products of the remaining two systems have not been identified. In this study, tandem MS was used to identify and quantify the AHL species produced by three clinical B. pseudomallei isolates – KHW, K96243 and H11 – three isogenic KHW mutants that each contain a null mutation in an AHL synthase gene, and recombinant Escherichia coli heterologously expressing each of the three B. pseudomallei AHL synthase genes. BpsI synthesized predominantly C8HL, which accounted for more than 95 % of the extracellular AHLs produced in stationary-phase KHW cultures. The major products of BpsI2 and BpsI3 were N-(3-hydroxy-octanoyl)homoserine lactone (OHC8HL) and N-(3-hydroxy-decanoyl)homoserine lactone, respectively, and their corresponding transcriptional regulators, BpsR2 and BpsR3, were capable of driving reporter gene expression in the presence of these cognate lactones. Formation of biofilm by B. pseudomallei KHW was severely impaired in mutants lacking either BpsI or BpsR but could be restored to near wild-type levels by exogenous C8HL. BpsI2 was not required, and BpsI3 was partially required for biofilm formation. Unlike the bpsI mutant, biofilm formation in the bpsI3
mutant could not be restored to wild-type levels in the presence of OHC8HL, the product of BpsI3. C8HL and OHC8HL had opposite effects on biofilm formation; exogenous C8HL enhanced biofilm formation in both the bpsI3
mutant and wild-type KHW while exogenous OHC8HL suppressed the formation of biofilm in the same strains. We propose that exogenous OHC8HL antagonizes biofilm formation in B. pseudomallei, possibly by competing with endogenous C8HL for binding to BpsR.
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Affiliation(s)
- Akshamal Mihiranga Gamage
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597 Singapore
| | - Guanghou Shui
- Life Science Institute, National University of Singapore, 28 Medical Drive, 117456 Singapore
| | - Markus R. Wenk
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, 117543 Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597 Singapore
| | - Kim Lee Chua
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597 Singapore
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99944
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Laichoubi KB, Beez S, Espinosa J, Forchhammer K, Contreras A. The nitrogen interaction network in Synechococcus WH5701, a cyanobacterium with two PipX and two PII-like proteins. Microbiology (Reading) 2011; 157:1220-1228. [DOI: 10.1099/mic.0.047266-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitrogen regulation involves the formation of different types of protein complexes between signal transducers and their transcriptional or metabolic targets. In oxygenic phototrophs, the signal integrator PII activates the enzyme N-acetyl-l-glutamate kinase (NAGK) by complex formation. PII also interacts with PipX, a protein with a tudor-like domain that mediates contacts with PII and with the transcriptional regulator NtcA, to which it binds to increase its activity. Here, we use a combination of in silico, yeast two-hybrid and in vitro approaches to investigate the nitrogen regulation network of Synechococcus WH5701, a marine cyanobacterium with two PII (GlnB_A and GlnB_B) and two PipX (PipX_I and PipX_II) proteins. Our results indicate that GlnB_A is functionally equivalent to the canonical PII protein from Synechococcus elongatus. GlnB_A interacted with PipX and NAGK proteins and stimulated NAGK activity, counteracting arginine inhibition. GlnB_B had only a slight stimulatory effect on NAGK activity, but its potential to bind effectors and form heterotrimers in Synechococcus WH5701 indicates additional regulatory functions. PipX_II, and less evidently PipX_I, specifically interacted with GlnB_A and NtcA, supporting a role for both Synechococcus WH5701 PipX proteins in partner swapping with GlnB_A and NtcA.
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Affiliation(s)
| | - Sabine Beez
- Lehrstuhl für Mikrobiologie, Organismische Interaktionen, University Tuebingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany
| | - Javier Espinosa
- División de Genética, Universidad de Alicante, Apartado 99, E-03080 Alicante, Spain
| | - Karl Forchhammer
- Lehrstuhl für Mikrobiologie, Organismische Interaktionen, University Tuebingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany
| | - Asunción Contreras
- División de Genética, Universidad de Alicante, Apartado 99, E-03080 Alicante, Spain
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99945
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Barišić L, Roščić M, Kovačević M, Semenčić MČ, Horvat Š, Rapić V. The first ferrocene analogues of muramyldipeptide. Carbohydr Res 2011; 346:678-84. [DOI: 10.1016/j.carres.2011.01.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 12/10/2010] [Accepted: 01/07/2011] [Indexed: 11/25/2022]
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99946
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Varrone JJ, Li D, Daiss JL, Schwarz EM. Anti-Glucosaminidase Monoclonal Antibodies as a Passive Immunization for Methicillin-Resistant Staphylococcus aureus (MRSA) Orthopaedic Infections. ACTA ACUST UNITED AC 2011; 8:187-194. [PMID: 22328866 DOI: 10.1138/20110506] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Recently, methicillin-resistant Staphylococcus aureus (MRSA) has surpassed HIV as the most deadly pathogen in the United States, accounting for over 100,000 deaths per year. In orthopedics, MRSA osteomyelitis has become the greatest concern in patient care, despite the fact that improvements in surgical technique and aggressive antibiotic prophylaxis have decreased the infection rate for most procedures to less than 5%. This great concern is largely due to the very poor outcomes associated with MRSA osteomyelitis, which includes 30-50% failure rates for revision surgery. Thus, there is a need to develop additional therapeutic interventions such as passive immunization, particularly for immunocompromised patients and the elderly who are typically poor responders to active vaccines. Using a novel murine model of implant-associated osteomyelitis in which a stainless steel pin is coated with bioluminescent S. aureus and implanted transcortically through the tibial metaphysis, we discovered that mice protect themselves from this infection by mounting a specific IgG2b response against the peptidoglycan hydrolase, glucosaminidase (Gmd), an enzyme involved in cell wall digestion during binary fission. Since this subunit of S. aureus autolysin is essential for bacterial growth, and no genetic variation has been identified among clinical strains, we propose that monoclonal antibodies against this enzyme would have multiple mechanisms of action, including promotion of opsonophagocytosis and direct inhibition of enzyme function. Here we review the field of MRSA osteomyelitis and our research to date on the development of an anti-Gmd passive immunotherapy.
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Affiliation(s)
- John J Varrone
- The Center for Musculoskeletal Research, University of Rochester, Rochester, New York, USA
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99947
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Rezende MUD, Silva RBBD, Bassit ACF, Tatsui NH, Sadigursky D, Bolliger Neto R. Efeito do Plasma Rico em Plaquetas na apoptose pós-traumática de condrócitos. ACTA ORTOPEDICA BRASILEIRA 2011. [DOI: 10.1590/s1413-78522011000200008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
OBJETIVO: Avaliar se a injeção intra-articular de Plasma rico em plaquetas (PRP) pode reduzir a apoptose pós-traumática de condrócitos. MÉTODOS: Foi desenvolvido um estudo experimental duplo-cego com quatro joelhos de coelhos adultos. Após a anestesia, os animais foram submetidos à contusão padronizada dos joelhos. Depois foi injetado 1ml de PRP humano nos dois joelhos esquerdos e 1ml de solução fisiológica (SF) nos dois joelhos direitos. Os dois coelhos foram mantidos no mesmo ambiente sob controle de temperatura, de atividades diárias e de alimentação. A eutanásia dos animais ocorreu dez dias após a intervenção e foram realizadas biópsias da cartilagem de cada joelho. As peças foram preparadas para análise em microscopia eletrônica (ME). RESULTADOS: Quatro preparados para ME foram obtidos, cada um correspondendo a um joelho. Os joelhos-PRP apresentaram as taxas de apoptose de 47,62% (50/105) e de 48,36% (59/122), respectivamente. Nos joelhos-SF as taxas de apoptose foram, respectivamente, 56,67% (17/30) e 70,40% (88/125). A diferença do índice de apoptose nos joelhos-PRP (48,02%) e nos joelhos-SF (67,74%) foi significante (p<0,001) e OR=0,439 (IC95%=0.287-0.673). CONCLUSÃO: A injeção intra-articular de PRP imediatamente ao trauma, reduz as taxas de apoptose (pós-traumática) de condrócitos de coelhos.
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99948
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Park SJ, Kim HK, Song DS, Moon HJ, Park BK. Molecular characterization and phylogenetic analysis of porcine epidemic diarrhea virus (PEDV) field isolates in Korea. Arch Virol 2011; 156:577-85. [PMID: 21210162 PMCID: PMC7086862 DOI: 10.1007/s00705-010-0892-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 12/10/2010] [Indexed: 11/25/2022]
Abstract
Porcine epidemic diarrhea virus (PEDV) has caused enteric disease with devastating impact since the first identification of PEDV in 1992 in Korea. In this study, we investigated molecular epidemiology, showed genetic diversity, and analyzed phylogenetic relationships of Korean PEDV field isolates with other PEDV reference strains. Genetic analysis of the complete M and ORF3 genes showed that each PEDV group had several unique characteristics, and this indicated that specific groups of PEDVs may be differentiated from the other PEDVs by specific nucleotide differences. Especially, ORF3 gene analysis can be used for discrimination between vaccine and wild-type PEDVs. Sequence and phylogenetic analysis showed that recent, prevalent Korean PEDV field isolates have close relationships to Chinese field strains and differ genetically from European strains and vaccine strains used in Korea. These results raise questions as to whether a new type of PEDV vaccine may be necessary for preventing PEDV infection more effectively in Korea.
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Affiliation(s)
- Seong-Jun Park
- Department of Veterinary Medicine Virology Lab, College of Veterinary Medicine and BK21 Program for Veterinary Science, Seoul National University, Gwanak-gu, Seoul, 151-742 Korea
| | - Hye-Kwon Kim
- Department of Veterinary Medicine Virology Lab, College of Veterinary Medicine and BK21 Program for Veterinary Science, Seoul National University, Gwanak-gu, Seoul, 151-742 Korea
| | - Dae-Sub Song
- Viral Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 305-806 Korea
| | - Hyoung-Joon Moon
- Research Unit, Green Cross Veterinary Products, Yongin, 449-903 Korea
| | - Bong-Kyun Park
- Department of Veterinary Medicine Virology Lab, College of Veterinary Medicine and BK21 Program for Veterinary Science, Seoul National University, Gwanak-gu, Seoul, 151-742 Korea
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99949
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Oh SY, Budzik JM, Garufi G, Schneewind O. Two capsular polysaccharides enable Bacillus cereus G9241 to cause anthrax-like disease. Mol Microbiol 2011; 80:455-70. [PMID: 21371137 PMCID: PMC3538873 DOI: 10.1111/j.1365-2958.2011.07582.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bacillus cereus G9241 causes an anthrax-like respiratory illness in humans; however, the molecular mechanisms of disease pathogenesis are not known. Genome sequencing identified two putative virulence plasmids proposed to provide for anthrax toxin (pBCXO1) and/or capsule expression (pBC218). We report here that B. cereus G9241 causes anthrax-like disease in immune-competent mice, which is dependent on each of the two virulence plasmids. pBCXO1 encodes pagA1, the homologue of anthrax protective antigen, as well as hasACB, providing for hyaluronic acid capsule formation, two traits that each contribute to disease pathogenesis. pBC218 harbours bpsX-H, B. cereus exo-polysaccharide, which produce a second capsule. During infection, B. cereus G9241 elaborates both hasACB and bpsX-H capsules, which together are essential for the establishment of anthrax-like disease and the resistance of bacilli to phagocytosis. A single nucleotide deletion causes premature termination of hasA translation in Bacillus anthracis, which is known to escape phagocytic killing by its pXO2 encoded poly-d-γ-glutamic acid (PDGA) capsule. Thus, multiple different gene clusters endow pathogenic bacilli with capsular material, provide for escape from innate host immune responses and aid in establishing the pathogenesis of anthrax-like disease.
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Affiliation(s)
- So-Young Oh
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA
- Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Jonathan M. Budzik
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA
| | - Gabriella Garufi
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA
- Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA
- Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Argonne, IL 60439, USA
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99950
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Fauvart M, De Groote VN, Michiels J. Role of persister cells in chronic infections: clinical relevance and perspectives on anti-persister therapies. J Med Microbiol 2011; 60:699-709. [PMID: 21459912 DOI: 10.1099/jmm.0.030932-0] [Citation(s) in RCA: 298] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Certain infectious diseases caused by pathogenic bacteria are typically chronic in nature. Potentially deadly examples include tuberculosis, caused by Mycobacterium tuberculosis, cystic fibrosis-associated lung infections, primarily caused by Pseudomonas aeruginosa, and candidiasis, caused by the fungal pathogen Candida albicans. A hallmark of this type of illness is the recalcitrance to treatment with antibiotics, even in the face of laboratory tests showing the causative agents to be sensitive to drugs. Recent studies have attributed this treatment failure to the presence of a small, transiently multidrug-tolerant subpopulation of cells, so-called persister cells. Here, we review our current understanding of the role that persisters play in the treatment and outcome of chronic infections. In a second part, we offer a perspective on the development of anti-persister therapies based on genes and mechanisms that have been implicated in persistence over the last decade.
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Affiliation(s)
- Maarten Fauvart
- Centre of Microbial and Plant Genetics, K.U.Leuven, Leuven, Belgium
| | | | - Jan Michiels
- Centre of Microbial and Plant Genetics, K.U.Leuven, Leuven, Belgium
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