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Genetic Analysis of the Capsular Biosynthetic Locus from All 90 Pneumococcal Serotypes
Stephen D Bentley ,David M Aanensen,Angeliki Mavroidi,David Saunders,Ester Rabbinowitsch,Matthew Collins,Kathy Donohoe,David Harris,Lee Murphy,Michael A Quail,Gabby Samuel,Ian C Skovsted,Margit Staum Kaltoft,Bart Barrell,Peter R Reeves,Julian Parkhill,Brian G Spratt
PLOS Genetics , 2006, DOI: 10.1371/journal.pgen.0020031
Abstract: Several major invasive bacterial pathogens are encapsulated. Expression of a polysaccharide capsule is essential for survival in the blood, and thus for virulence, but also is a target for host antibodies and the basis for effective vaccines. Encapsulated species typically exhibit antigenic variation and express one of a number of immunochemically distinct capsular polysaccharides that define serotypes. We provide the sequences of the capsular biosynthetic genes of all 90 serotypes of Streptococcus pneumoniae and relate these to the known polysaccharide structures and patterns of immunological reactivity of typing sera, thereby providing the most complete understanding of the genetics and origins of bacterial polysaccharide diversity, laying the foundations for molecular serotyping. This is the first time, to our knowledge, that a complete repertoire of capsular biosynthetic genes has been available, enabling a holistic analysis of a bacterial polysaccharide biosynthesis system. Remarkably, the total size of alternative coding DNA at this one locus exceeds 1.8 Mbp, almost equivalent to the entire S. pneumoniae chromosomal complement.
Meningococcal Genetic Variation Mechanisms Viewed through Comparative Analysis of Serogroup C Strain FAM18
Stephen D Bentley ,George S Vernikos,Lori A. S Snyder,Carol Churcher,Claire Arrowsmith,Tracey Chillingworth,Ann Cronin,Paul H Davis,Nancy E Holroyd,Kay Jagels,Mark Maddison,Sharon Moule,Ester Rabbinowitsch,Sarah Sharp,Louise Unwin,Sally Whitehead,Michael A Quail,Mark Achtman,Bart Barrell,Nigel J Saunders,Julian Parkhill
PLOS Genetics , 2007, DOI: 10.1371/journal.pgen.0030023
Abstract: The bacterium Neisseria meningitidis is commonly found harmlessly colonising the mucosal surfaces of the human nasopharynx. Occasionally strains can invade host tissues causing septicaemia and meningitis, making the bacterium a major cause of morbidity and mortality in both the developed and developing world. The species is known to be diverse in many ways, as a product of its natural transformability and of a range of recombination and mutation-based systems. Previous work on pathogenic Neisseria has identified several mechanisms for the generation of diversity of surface structures, including phase variation based on slippage-like mechanisms and sequence conversion of expressed genes using information from silent loci. Comparison of the genome sequences of two N. meningitidis strains, serogroup B MC58 and serogroup A Z2491, suggested further mechanisms of variation, including C-terminal exchange in specific genes and enhanced localised recombination and variation related to repeat arrays. We have sequenced the genome of N. meningitidis strain FAM18, a representative of the ST-11/ET-37 complex, providing the first genome sequence for the disease-causing serogroup C meningococci; it has 1,976 predicted genes, of which 60 do not have orthologues in the previously sequenced serogroup A or B strains. Through genome comparison with Z2491 and MC58 we have further characterised specific mechanisms of genetic variation in N. meningitidis, describing specialised loci for generation of cell surface protein variants and measuring the association between noncoding repeat arrays and sequence variation in flanking genes. Here we provide a detailed view of novel genetic diversification mechanisms in N. meningitidis. Our analysis provides evidence for the hypothesis that the noncoding repeat arrays in neisserial genomes (neisserial intergenic mosaic elements) provide a crucial mechanism for the generation of surface antigen variants. Such variation will have an impact on the interaction with the host tissues, and understanding these mechanisms is important to aid our understanding of the intimate and complex relationship between the human nasopharynx and the meningococcus.
The genome of Rhizobium leguminosarum has recognizable core and accessory components
J Peter W Young, Lisa C Crossman, Andrew WB Johnston, Nicholas R Thomson, Zara F Ghazoui, Katherine H Hull, Margaret Wexler, Andrew RJ Curson, Jonathan D Todd, Philip S Poole, Tim H Mauchline, Alison K East, Michael A Quail, Carol Churcher, Claire Arrowsmith, Inna Cherevach, Tracey Chillingworth, Kay Clarke, Ann Cronin, Paul Davis, Audrey Fraser, Zahra Hance, Heidi Hauser, Kay Jagels, Sharon Moule, Karen Mungall, Halina Norbertczak, Ester Rabbinowitsch, Mandy Sanders, Mark Simmonds, Sally Whitehead, Julian Parkhill
Genome Biology , 2006, DOI: 10.1186/gb-2006-7-4-r34
Abstract: The 7.75 Mb genome comprises a circular chromosome and six circular plasmids, with 61% G+C overall. All three rRNA operons and 52 tRNA genes are on the chromosome; essential protein-encoding genes are largely chromosomal, but most functional classes occur on plasmids as well. Of the 7,263 protein-encoding genes, 2,056 had orthologs in each of three related genomes (Agrobacterium tumefaciens, Sinorhizobium meliloti, and Mesorhizobium loti), and these genes were over-represented in the chromosome and had above average G+C. Most supported the rRNA-based phylogeny, confirming A. tumefaciens to be the closest among these relatives, but 347 genes were incompatible with this phylogeny; these were scattered throughout the genome but were over-represented on the plasmids. An unexpectedly large number of genes were shared by all three rhizobia but were missing from A. tumefaciens.Overall, the genome can be considered to have two main components: a 'core', which is higher in G+C, is mostly chromosomal, is shared with related organisms, and has a consistent phylogeny; and an 'accessory' component, which is sporadic in distribution, lower in G+C, and located on the plasmids and chromosomal islands. The accessory genome has a different nucleotide composition from the core despite a long history of coexistence.The symbiosis between legumes and N2-fixing bacteria (rhizobia) is of huge agronomic benefit, allowing many crops to be grown without N fertilizer. It is a sophisticated example of coupled development between bacteria and higher plants, culminating in the organogenesis of root nodules [1]. There have been many genetic analyses of rhizobia, notably of Sinorhizobium meliloti (the symbiont of alfalfa), Bradyrhizobium japonicum (soybean), and Rhizobium leguminosarum, which has biovars that nodulate peas and broad beans (biovar viciae), clovers (biovar trifolii), or kidney beans (biovar phaseoli).The Rhizobiales, an α-proteobacterial order that also includes mammalian pathogens B
Rapid Evolution of Virulence and Drug Resistance in the Emerging Zoonotic Pathogen Streptococcus suis
Matthew T. G. Holden, Heidi Hauser, Mandy Sanders, Thi Hoa Ngo, Inna Cherevach, Ann Cronin, Ian Goodhead, Karen Mungall, Michael A. Quail, Claire Price, Ester Rabbinowitsch, Sarah Sharp, Nicholas J. Croucher, Tran Bich Chieu, Nguyen Thi Hoang Mai, To Song Diep, Nguyen Tran Chinh, Michael Kehoe, James A. Leigh, Philip N. Ward, Christopher G. Dowson, Adrian M. Whatmore, Neil Chanter, Pernille Iversen, Marcelo Gottschalk, Josh D. Slater, Hilde E. Smith, Brian G. Spratt, Jianguo Xu, Changyun Ye, Stephen Bentley, Barclay G. Barrell, Constance Schultsz, Duncan J. Maskell, Julian Parkhill
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006072
Abstract: Background Streptococcus suis is a zoonotic pathogen that infects pigs and can occasionally cause serious infections in humans. S. suis infections occur sporadically in human Europe and North America, but a recent major outbreak has been described in China with high levels of mortality. The mechanisms of S. suis pathogenesis in humans and pigs are poorly understood. Methodology/Principal Findings The sequencing of whole genomes of S. suis isolates provides opportunities to investigate the genetic basis of infection. Here we describe whole genome sequences of three S. suis strains from the same lineage: one from European pigs, and two from human cases from China and Vietnam. Comparative genomic analysis was used to investigate the variability of these strains. S. suis is phylogenetically distinct from other Streptococcus species for which genome sequences are currently available. Accordingly, ~40% of the ~2 Mb genome is unique in comparison to other Streptococcus species. Finer genomic comparisons within the species showed a high level of sequence conservation; virtually all of the genome is common to the S. suis strains. The only exceptions are three ~90 kb regions, present in the two isolates from humans, composed of integrative conjugative elements and transposons. Carried in these regions are coding sequences associated with drug resistance. In addition, small-scale sequence variation has generated pseudogenes in putative virulence and colonization factors. Conclusions/Significance The genomic inventories of genetically related S. suis strains, isolated from distinct hosts and diseases, exhibit high levels of conservation. However, the genomes provide evidence that horizontal gene transfer has contributed to the evolution of drug resistance.
Marx e a Filosofia: elementos para a discuss?o ainda necessária
Vaisman, Ester;
Nova Economia , 2006, DOI: 10.1590/S0103-63512006000200005
Abstract: the main objective of this article is to reexamine an old controversy between analysts of marx: the relationship between marxist thought and philosophy, as well as the issue of methodology. the purpose is not to reach a final conclusion on such an intriguing topic, but rather to point out some elements that will show that this topic is far from "worn out." to the contrary. after outlining the critical relationship between marx and the classical german tradition, which is perhaps responsible for so much confusion, the article seeks to clarify how marx understands and conceives the operative functions of reason, as well as the role that objectivity plays in his theoretical path. in addition, this article raises the issue of the character that knowledge assumes in his theoretical corpus: is it speculative knowledge or the knowledge of transformation? finally, the article examines the character of the materialism initiated by marx, as well as references made in capital to hegelian dialectic.
Confiabilidad y validez de los instrumentos de evaluación neuropsicológica
Subjetividad y procesos cognitivos , 2011,
Abstract: the problem with psychological assessment in general and with that of cognitive functions in particular, presents methodological and transcultural challenges. instruments for assessing cognitive functions are not exempt from these difficulties. however, it would be interesting to refer to the similarities and differences regarding the approach of psychological assessment and that of the neuropsychological one. although the two types of assessments tend to propose diagnostic hypothesis, explain pathological behavior and enlighten on possible normal functioning, both include psychometrics in their methodology and therefore use valid and reliable instruments. the professional's knowledge of himself should encompass his roots and culture in order that he might be aware of the fact that his work is that of a "ser inserto en una cultura" (a being embedded in a certain culture), benet (1986, cited by renata frank de verthelyi).
O "jovem" Lukács: trágico, utópico e romantico?
Vaisman, Ester;
Kriterion: Revista de Filosofia , 2005, DOI: 10.1590/S0100-512X2005000200013
Abstract: given the controversial character of "young" lukács' intellectual path, essentially concerning to the works the soul and the forms and theory of the romance, the central objective of the present article is to delineate with wide lines the path of lukács in his youth phase (based on their own texts and testimonies) and, thus, to discuss certain attributions done for this important period of his intellectual production.
Mais idade e menos cidadania
Análise Psicológica , 1998,
Abstract: the article reports the results of a study about the social integration of elderly people with functional autonomy, in terms of their well-being in urban and rural environments. main analysis factors: the relationship established between the social equipments for elderly people and the personal satisfaction level that is felt; the conditions personal protagonism in the elderly people's afectivity, socialization and autonomy in the family and social environments. the results obtained suggest the existence of sociability and solidarity, both in the family and the neighbourhood levels, felt more strongly in rural environments. moreover, the strict rules involving the functioning and the distancing of the family groups of elderly people, imposed by social equipment, work negatively on the elderly people's personal fulfilment. furthermore, the constant support given by the elderly people to their families and especially to their grandchildren becomes, to themselves, an important way of social integration, not easily recognised but with great social value.
Investigación científica y tecnológica en el campo de las TIC: ?conocimientos técnicos, contextuales o transversales?
Revista iberoamericana de ciencia tecnolog?-a y sociedad , 2007,
Abstract: during the last decade, s&t research on the field of information and communication technologies (ict) has grown dramatically in argentina. as a consequence of this process, today it is possible to see that the disciplines involved in this field widely exceed those considered as specific, since exact sciences and engineering, devoted to the study of these technologies in particular, are more and more accompanied by natural and social sciences, humanities and different expressions of art. the goal of this paper is to know what is researched in the field of ict in argentina, in order to analyse which kind of knowledge is produced and to what extent it contributes to the country's economic and social development. the information surveyed made it possible to make a first approach to the network of links between the different fields of knowledge addressing the issue and those sectors of society to which the produced knowledge is transferred.
A obra tardia de Lukács e os revezes de seu itinerário intelectual
Vaisman, Ester;
Trans/Form/A??o , 2007, DOI: 10.1590/S0101-31732007000200016
Abstract: this article's main purpose is to point out the most striking features on g. lukács latest works, focusing particularly on the ontology of social being. it will also elaborate on his intellectual trajectory.
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