951 resultados para Locus de contrôle


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Introduction: Although Enterococcus faecalis is a member of the normal microbiota, it is also a major cause of nosocomial infections. Some strains of E. faecalis produce capsule, which contributes to pathogenesis through evasion of host defenses, and its production is dependent on the capsule (cps) operon polymorphism. This study investigated cps locus polymorphism in distinct lineages of E. faecalis isolated from canals of root-filled teeth with periapical lesions. Methods: Twenty-two E. faecalis isolates were evaluated regarding the cps operon polymorphism and genetic diversity. The 3 known CPS types were determined by polymerase chain reaction. This information was correlated with multilocus sequence typing data, which were used to define genetic lineages. Results: cpsA and cpsB were the only detected genes within the cps operon in 62.5% of E. faecalis strains (14/22), indicative of genotype CPS 1, which lacks capsule expression. The essential genes in the cps operon for capsule production were detected in the remaining strains, whereas 3 belonged to genotype CPS 5 and 5 strains to genotype CPS 2. A total of 14 sequence types (STs) were resolved in 22 E. faecalis isolates. Comparison with the E. faecalis international multilocus sequence typing database revealed that 9 STs were previously found, and that the 5 STs were novel. Conclusions: Certain E. faecalis genotypes from canals of root-filled teeth with periapical lesions belong to lineages associated with capsule expression and production of multiple virulence factors, which might account for their increased pathogenic potential. (J Endod 2012;38:58-61)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The non-classical human leukocyte antigen (HLA) class I genes present a very low rate of variation. So far, only 10 HLA-E alleles encoding three proteins have been described, but only two are frequently found in worldwide populations. Because of its historical background, Brazilians are very suitable for population genetic studies. Therefore, 104 bone marrow donors from Brazil were evaluated for HLA-E exons 14. Seven variation sites were found, including two known single nucleotide polymorphisms (SNPs) at positions +424 and +756 and five new SNPs at positions +170 (intron 1), +1294 (intron 3), +1625, +1645 and +1857 (exon 4). Haplotyping analysis did show eight haplotypes, three of them known as E*01:01:01, E*01:03:01 and E*01:03:02:01 and five HLA-E new alleles that carry the new variation sites. The HLA-E*01:01:01 allele was the predominant haplotype (62.50%), followed by E*01:03:02:01 (24.52%). Selective neutrality tests have disclosed an interesting pattern of selective pressures in which balancing selection is probably shaping allele frequency distributions at an SNP at exon 3 (codon 107), sequence diversity at exon 4 and the non-coding regions is facing significant purifying pressure. Even in an admixed population such as the Brazilian one, the HLA-E locus is very conserved, presenting few polymorphic SNPs in the coding region.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

BACKGROUND: Nonsyndromic cleft lip with or without cleft palate is a relatively common craniofacial defect with multifactorial inheritance. The association of the rs987525 single nucleotide variant, located in a gene desert at 8q24.21 region, has been consistently replicated in European populations. We performed a structured association approach combined with transcriptional analysis of the MYC gene to dissect the role of rs987525 in oral clefting susceptibility in the ethnically admixed Brazilian population. METHODS: We performed the association study conditioned on the individual ancestry proportions in a sample of 563 patients and 336 controls, and in an independent sample of 221 patients and 261 controls. The correlation between rs987525 genotypes and MYC transcriptional levels in orbicularis oris muscle mesenchymal stem cells was also investigated in 42 patients and 4 controls. RESULTS: We found a significant association in the larger sample (p = 0.0016; OR = 1.80 [95% confidence interval {CI}, 1.21-2.69], for heterozygous genotype, and 2.71 [95% CI, 1.47-4.96] for homozygous genotype). We did not find a significant correlation between rs987525 genotypes and MYC transcriptional levels (p = 0.14; r = -0.22, Spearman Correlation). CONCLUSIONS: We present a positive association of rs987525 in the Brazilian population for the first time, and it is likely that the European contribution to our population is driving this association. We also cannot discard a role of rs987515 in MYC regulation, because this locus behaves as an expression quantitative locus of MYC in another tissue. Birth Defects Research (Part A) 94:464-468, 2012. (C) 2012 Wiley Periodicals, Inc.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Emerging resistance to chloroquine (CQ) poses a major challenge for Plasmodium vivax malaria control, and nucleotide substitutions and copy number variation in the P. vivax multidrug resistance 1 (pvmdr-1) locus, which encodes a digestive vacuole membrane transporter, may modulate this phenotype. We describe patterns of genetic variation in pvmdr-1 alleles from Acre and Amazonas in northwestern Brazil, and compare then with those reported in other malaria-endemic regions. The pvmdr-1 mutation Y976F, which is associated with CQ resistance in Southeast Asia and Oceania, remains rare in northwestern Brazil (1.8%) and its prevalence mirrors that of CO resistance worldwide. Gene amplification of pvmdr-1, which is associated with mefloquine resistance but increased susceptibility to CO, remains relatively rare in northwestern Brazil (0.9%) and globally (< 4%), but became common (> 10%) in Tak Province, Thailand, possibly because of drug-mediated selection. The global database we have assembled provides a baseline for further studies of genetic variation in pvmdr-1 and drug resistance in P. vivax malaria.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Abstract Background Despite the extensive polymorphism at the merozoite surface protein-1 (MSP-1) locus of Plasmodium falciparum, that encodes a major repetitive malaria vaccine candidate antigen, identical and nearly identical alleles frequently occur in sympatric parasites. Here we used microsatellite haplotyping to estimate the genetic distance between isolates carrying identical and nearly identical MSP-1 alleles. Methods We analyzed 28 isolates from hypoendemic areas in north-western Brazil, collected between 1985 and 1998, and 23 isolates obtained in mesoendemic southern Vietnam in 1996. MSP-1 alleles were characterized by combining PCR typing with allele-specific primers and partial DNA sequencing. The following single-copy microsatellite markers were typed : Polyα, TA42 (only for Brazilian samples), TA81, TA1, TA87, TA109 (only for Brazilian samples), 2490, ARAII, PfG377, PfPK2, and TA60. Results The low pair-wise average genetic distance between microsatellite haplotypes of isolates sharing identical MSP-1 alleles indicates that epidemic propagation of discrete parasite clones originated most identical MSP-1 alleles in parasite populations from Brazil and Vietnam. At least one epidemic clone propagating in Brazil remained relatively unchanged over more than one decade. Moreover, we found no evidence that rearrangements of MSP-1 repeats, putatively created by mitotic recombination events, generated new alleles within clonal lineages of parasites in either country. Conclusion Identical MSP-1 alleles originated from co-ancestry in both populations, whereas nearly identical MSP-1 alleles have probably appeared independently in unrelated parasite lineages.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Abstract Background The ability to successfully identify and incriminate pathogen vectors is fundamental to effective pathogen control and management. This task is confounded by the existence of cryptic species complexes. Molecular markers can offer a highly effective means of species identification in such complexes and are routinely employed in the study of medical entomology. Here we evaluate a multi-locus system for the identification of potential malaria vectors in the Anopheles strodei subgroup. Methods Larvae, pupae and adult mosquitoes (n = 61) from the An. strodei subgroup were collected from 21 localities in nine Brazilian states and sequenced for the COI, ITS2 and white gene. A Bayesian phylogenetic approach was used to describe the relationships in the Strodei Subgroup and the utility of COI and ITS2 barcodes was assessed using the neighbor joining tree and “best close match” approaches. Results Bayesian phylogenetic analysis of the COI, ITS2 and white gene found support for seven clades in the An. strodei subgroup. The COI and ITS2 barcodes were individually unsuccessful at resolving and identifying some species in the Subgroup. The COI barcode failed to resolve An. albertoi and An. strodei but successfully identified approximately 92% of all species queries, while the ITS2 barcode failed to resolve An. arthuri and successfully identified approximately 60% of all species queries. A multi-locus COI-ITS2 barcode, however, resolved all species in a neighbor joining tree and successfully identified all species queries using the “best close match” approach. Conclusions Our study corroborates the existence of An. albertoi, An. CP Form and An. strodei in the An. strodei subgroup and identifies four species under An. arthuri informally named A-D herein. The use of a multi-locus barcode is proposed for species identification, which has potentially important utility for vector incrimination. Individuals previously found naturally infected with Plasmodium vivax in the southern Amazon basin and reported as An. strodei are likely to have been from An. arthuri C identified in this study.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Human endogenous retroviruses (HERVs) arise from ancient infections of the host germline cells by exogenous retroviruses, constituting 8% of the human genome. Elevated level of envelope transcripts from HERVs-W has been detected in CSF, plasma and brain tissues from patients with Multiple Sclerosis (MS), most of them from Xq22.3, 15q21.3, and 6q21 chromosomes. However, since the locus Xq22.3 (ERVWE2) lack the 5' LTR promoter and the putative protein should be truncated due to a stop codon, we investigated the ERVWE2 genomic loci from 84 individuals, including MS patients with active HERV-W expression detected in PBMC. In addition, an automated search for promoter sequences in 20 kb nearby region of ERVWE2 reference sequence was performed. Several putative binding sites for cellular cofactors and enhancers were found, suggesting that transcription may occur via alternative promoters. However, ERVWE2 DNA sequencing of MS and healthy individuals revealed that all of them harbor a stop codon at site 39, undermining the expression of a full-length protein. Finally, since plaque formation in central nervous system (CNS) of MS patients is attributed to immunological mechanisms triggered by autoimmune attack against myelin, we also investigated the level of similarity between envelope protein and myelin oligodendrocyte glycoprotein (MOG). Comparison of the MOG to the envelope identified five retroviral regions similar to the Ig-like domain of MOG. Interestingly, one of them includes T and B cell epitopes, capable to induce T effector functions and circulating Abs in rats. In sum, although no DNA substitutions that would link ERVWE2 to the MS pathogeny was found, the similarity between the envelope protein to MOG extends the idea that ERVEW2 may be involved on the immunopathogenesis of MS, maybe facilitating the MOG recognizing by the immune system. Although awaiting experimental evidences, the data presented here may expand the scope of the endogenous retroviruses involvement on MS pathogenesis

Relevância:

20.00% 20.00%

Publicador:

Resumo:

[EN] The groups of local cohomology with supports in the non-free locus of a module are used in order to obtain three classifications and one characterization of four classes of modules

Relevância:

20.00% 20.00%

Publicador:

Resumo:

VILLA “CAPELLO - MORA”: PROGETTO DI RESTAURO E RIFUNZIONALIZZAZIONE Il restauro è da intendere come un intervento diretto sull’opera, e anche come sua eventuale modifica, condotta sempre sotto un rigoroso controllo tecnico-scientifico e storico-critico, se parliamo di conservazione, intendiamo l’operare in un intento di salvaguardia e di prevenzione, da attuare proprio per evitare che si debba poi intervenire con il restauro, che comprende un evento traumatico per il manufatto. Un seconda parola chiave in questo discorso è la “materia” il restauro interviene sulla materia di un monumento e questa costituisce il tramite dei valori culturali antichi, la sua conservazione e il suo restauro garantisce la trasmissione anche dei significati estetici, storici simbolici del costruito. Ma certamente influisce il tempo sulle cose per cui il progetto di restauro non può astenersi dall’intervenire, in una logica di minimo intervento, di reversibilità, di facile lettura. Il concetto di nuovo in un opera antica, concetto che a parere personale, pare centrare in pieno il problema. Il nuovo infatti “deve avere carattere di autonomia e di chiara leggibilità: come l’<> di Boito deve essere inequivocabilmente opera nuova, come prodotto figurativo e materiale autonomo, chiara ed inequivocabile espressione <<della nostra cultura e del nostro tempo>>”. Ne deriva riassumendo che oggi l’obbiettivo deve essere quello di conservare da un lato senza non sotrarre altra materia alla fabbrica e di valorizzare, ossia aggiungere, nuove “presenze” di cultura contemporanea. Per questo si parlerà di progetto di restauro e rifunzionalizzazione. La fabbrica ha subito nel corso dell’ultimo decennio una serie di “rovinose” manomissioni, che a differenza di quelle operate in tempi più antichi (coincidenti con esigenze funzionali corrispondenti alla logica dell’adattare) appaiano ben più gravi, e contribuiscono a peggiorare la lettura del fabbricato. Il Veneto e soprattutto la zona intorno a Bassano del Grappa presenta una infinità di dimore padronali casini di caccia, resti di antiche residenze (colombare, oratori, ecc.) risalenti al periodo di maggior fioritura della residenza di “Villa” della Serenissima. Nel caso specifico di studio , quindi della rifunzionalizzazione dell’edificio, la domanda sorge spontanea; Come ristabilire un senso a questi spazi? E nell’ipotesi di poter realmente intervenire che cosa farne di questi oggetti?. E ultimo ma non ultimo in che modo poter ristabilire un “dialogo” con l’edificio in una lettura corretta del suo significato non solo per quel che riguarda la materia ma anche per ciò che ci trasmette nel “viverlo”, nell’usufruirne nel fatto stesso di poterlo vedere, passandoci davanti. tà. Lidea si forma prima ancora da un esigenza del territorio, il comune di Cassola dove ha sede la Villa,pur avendo un discreto numero di abitanti e collocandosi in posizione nevralgica in quanto molto vicino al centro diBasssano (ne è quasi la promulgazione), non possiede uno spazio espositivo /rappresentativo, un edificio a carattere pubblico, sede di “eventi” culturali locali e non. Villa Capello –Mora, potrebbe rispondere bene a questo tipo di utilizzo. Si è deciso di pensare ad un luogo a carattere espositivo che possa funzionare durante tutto l’anno e nei periodi etsivi includa anche il giardino esterno. Il progetto muove da due principi il principio di “reversibilità” e quello del “minimo intervento” sottolinenando volutamente che siano gli ogetti esposti e lo spazio dei locali a fare da protagonisti, Punti chiave nell’interpretazione degli spazi sono stati i percorsi, la “narrazione” degli oggetti esposti avviene per momenti e viene rimarcata nell’allestimento tramite i materiali i colori e le superfici espositive, perché nel momento in cui visito una mostra o un museo, è come se stessi vivendo la narrazione di un qualcosa, oggetto semplice od opera complessa che sia inteso nell’ambito museale-espositivo esso assume una capacità di trasmissione maggiore rispetto a qundo lo stesso ogetto si trova in un contesto differente, la luce e la sua disposizione nello spazio, fanno sì che il racconto sia narrato, bene o male, ancora più importante è lo sfondo su cui si staglia l’opera, che può essere chiuso, come una serie di scatole dentro la scatola (edificio) oppure aperto, con singole e indipendenti pannellature dove l’edificio riveste il carattere proprio di sfondo. Scelta la seconda delle due ipotesi, si è voluto rimarcare nella composizione degli interni i momenti della narrazione, così ad esempio accedendo dall’ingresso secondario (lato nord-ovest) al quale si è dato l’ingresso alla mostra, -superata la prima Hall- si viene, catapultati in uno spazio porticato in origine aperto e che prevediamo chiuso da una vetrata continua, portata a debita distanza dal colonnato. Questo spazio diventa la prima pagina del testo, una prima pagina bianca, uno spazio libero, di esposizione e non di relax e di presentazione dell’evento, uno spazio distributivo non votato solo a questo scopo, ma passibile di trasformazione. A rimarcare il percorso una pavimentazione in cemento lisciato, che invita l’accesso alle due sale espositive a sinista e a destra dell’edificio. Nell’ala a sinistra (rispetto al nord) si apre la stanza con camino seicentesco forse un tempo ad uso cucina? Sala che ospita dei pannelli a sospesi a muro e delle teche espositive appese a soffitto. L’ala di destra, diametralmente opposta, l’unica che al piano terra mantiene la pavimentazione originale, stabiliva il vero atrio d’entrata, nel XVII sec. riconoscibile da quattro colonne tuscaniche centrali a reggere un solaio ligneo, in questa stanza il percorso segnato a terra torna nella disposizione dei pannelli espositivi che si dispongono in un a formare un vero corridoio, tra uno e l’atro di questi pannelli degli spazi sufficienti a intravedere le colonne centrali, i due lati dello stretto percorso non sono paralleli e aprono in senso opposto a due restanti spazi dell’intero salone, La sala suddivisa così in queste tre parti - una di percorrenza due di esposizione - , risulta modificata nella lettura che ne annulla l’originale funzione. Questa nuova “forma”, non vuole essere permanente infatti i pannelli non sono fissi. la narrazione avviene così per momenti, per parti, , che non devono necessariamente far comprendere il “tutto”, ma suggerirlo. Così come per il percorso che non è obbligato ma suggerito. A terminare il piano altre due sale di minore dimensione e di modesto carattere, nelle quali sono presenti pannellature a parete come nella prima sala. L’allestimento prosegue al piano primo a cui si accede tramite due rampe, trattate nel progetto difformemente, in base al loro stato e al loro significato, la rampa più recente (XIX sec) rompe lo spazio al piano nobile stravolgendo l’ingresso a questo salone, che originariamente avveniva salendo dalla scala principale e oltrepassando un disimpegno. La scala ottocentesca introduce direttamente all’ambiente che ora risulta liberato dalle superfetazioni dello scorso secolo, mostrandosi come era stato previsto in origine. Questa rottura dello spazio viene marcata nel progetto da un volume che “imprigiona” la rampa e segna l’inizio della sala espositiva, la sala delle architetture. Al centro della sala in un gioco di pieni e vuoti i pannelli, espositivi, distaccati di poco gli uni dagli altri questa volta non a incorniciare delle colonne ma a richiamo delle pitture murali che raffiguranti una loggia alludono ad una lettura per “parti” e scandiscono lo spazio in una “processione” di eventi. A seguito del “gioco” sono presenti in senso ortogonale ai pannelli sopradescritti ulteriori pannellature appese ad una struttura metallica indipendente dalle capriate lignee. Tale struttura assume ad una duplice funzione, funge sia da irrigidimento della struttura (edificio) che da supporto alla pannellatura, ad essa infatti è collegata una fune, che entrerà in tensione, quando il pannello verrà ad appendersi. Infine questa fune passante da due puleggie permetterà al pannello di traslare da un lato all’altro dell’edificio, bloccandosi nella posizione desiderata tramite freno interno, azionato manualmente.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The human DMD locus encodes dystrophin protein. Absence or reduced levels of dystrophin (DMD or BMD phenotype, respectively) lead to progressive muscle wasting. Little is known about the complex coordination of dystrophin expression and its transcriptional regulation is a field of intense interest. In this work we found that DMD locus harbours multiple long non coding RNAs which orchestrate and control transcription of muscle dystrophin mRNA isoforms. These lncRNAs are tissue-specific and highly expressed during myogenesis, suggesting a possible role in tissue-specific expression of DMD gene isoforms. Their forced ectopic expression in human muscle and neuronal cells leads to a specific and negative regulation of endogenous dystrophin full lenght isoforms. An intriguing aspect regarding the transcription of the DMD locus is the gene size (2.4Mb). The mechanism that ensures the complete synthesis of the primary transcript and the coordinated splicing of 79 exons is still completely unknown. By ChIP-on-chip analyses, we discovered novel regions never been involved before in the transcription regulation of the DMD locus. Specifically, we observed enrichments for Pol II, P-Ser2, P-Ser5, Ac-H3 and 2Me-H3K4 in an intronic region of 3Kb (approximately 21Kb) downstream of the end of DMD exon 52 and in a region of 4Kb spanning the DMD exon 62. Interestingly, this latter region and the TSS of Dp71 are strongly marked by 3Me-H3K36, an histone modification associated with the regulation of splicing process. Furthermore, we also observed strong presence of open chromatin marks (Ac-H3 and 2Me-H3K4) around intron 34 and the exon 45 without presence of RNA pol II. We speculate that these two regions may exert an enhancer-like function on Dp427m promoter, although further investigations are necessary. Finally, we investigated the nuclear-cytoplasmic compartmentalization of the muscular dystrophin mRNA and, specifically, we verified whether the exon skipping therapy could influence its cellular distribution.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We investigate the Torelli locus of abelian and cyclic covers of the projective line for occurrence of Shimura subvarieties. Amon other things, we show that under some conditions there are no Shimura subvarieties in this locus.