41 research outputs found
Reconstruction-Induced Josephson Effect in Quantum Spin Hall Constrictions
The simultaneous breaking of time-reversal and inversion symmetry, in
connection to superconductivity, leads to transport properties with disrupting
scientific and technological potential. Indeed, the anomalous Josephson effect
and the superconducting-diode effect hold promises to enlarge the technological
applications of superconductors and nanostructures in general. In this context,
the system we theoretically analyze is a Josephson junction (JJ) with coupled
reconstructed topological channels as a link; such channels are at the edges of
a two-dimensional topological insulator (2DTI). We find a robust
Josephson effect without requiring the presence of external magnetic fields.
Our results, which rely on a fully analytical analysis, are substantiated by
means of symmetry arguments: Our system breaks both time-reversal symmetry and
inversion symmetry. Moreover, the anomalous current increases as a function of
temperature. We interpret this surprising temperature dependence by means of
simple qualitative arguments based on Fermi's golden rule.Comment: 13 pages, 3 figure
Segtor: Rapid Annotation of Genomic Coordinates and Single Nucleotide Variations Using Segment Trees
Various research projects often involve determining the relative position of genomic coordinates, intervals, single nucleotide variations (SNVs), insertions, deletions and translocations with respect to genes and their potential impact on protein translation. Due to the tremendous increase in throughput brought by the use of next-generation sequencing, investigators are routinely faced with the need to annotate very large datasets. We present Segtor, a tool to annotate large sets of genomic coordinates, intervals, SNVs, indels and translocations. Our tool uses segment trees built using the start and end coordinates of the genomic features the user wishes to use instead of storing them in a database management system. The software also produces annotation statistics to allow users to visualize how many coordinates were found within various portions of genes. Our system currently can be made to work with any species available on the UCSC Genome Browser. Segtor is a suitable tool for groups, especially those with limited access to programmers or with interest to analyze large amounts of individual genomes, who wish to determine the relative position of very large sets of mapped reads and subsequently annotate observed mutations between the reads and the reference. Segtor (http://lbbc.inca.gov.br/segtor/) is an open-source tool that can be freely downloaded for non-profit use. We also provide a web interface for testing purposes
Challenges in the use of NG2 antigen as a marker to predict MLL rearrangements in multi-center studies
AbstractRearrangements in MLL (MLL-r) are common within very young children with leukemia and affect the prognosis and treatment. Previous studies have suggested the use of the NG2 molecule as a marker for MLL-r but these studies were performed using a small number of infants. We analyzed 148 patients (all less than 24 months, 86 less than 12 months) from various centers in Brazil to determine the predictive power of NG2 within that cohort. We show that NG2 can be used for MLL-r prediction; however, proper staff training and standardized sampling procedures are essential when receiving samples from multiple centers as the accuracy of the prediction varies greatly on a per center basis
Identical sequence patterns in the ends of exons and introns of human protein-coding genes
Intron splicing is one of the most important steps involved in the maturation process of a pre-mRNA. Although the sequence profiles around the splice sites have been studied extensively, the levels of sequence identity between the exonic sequences preceding the donor sites and the intronic sequences preceding the acceptor sites has not been examined as thoroughly. In this study we investigated identity patterns between the last 15 nucleotides of the exonic sequence preceding the 5' splice site and the intronic sequence preceding the 3' splice site in a set of human protein-coding genes that do not exhibit intron retention. We found that almost 60% of consecutive exons and introns in human protein-coding genes share at least two identical nucleotides at their 3' ends and, on average, the sequence identity length is 2.47 nucleotides. Based on our findings we conclude that the 3' ends of exons and introns tend to have longer identical sequences within a gene than when being taken from different genes. Our results hold even if the pairs are non-consecutive in the transcription order. (C) 2012 Elsevier Ltd. All rights reserved.CNPq [382791/2009-6]CNPqMCT/CT-SaudeMCT/CTSaudeDECIT/SCTIE/MSDECIT/SCTIE/MS [577593/2008-0, 312733/2009-7]Swiss Bridge FoundationSwiss Bridge FoundationFundacao do CancerFundacao do CancerINCA/MSINCA/MSAssociacao Beneficente Alzira Denise Hertzog Silva (ABADHS)Associacao Beneficente Alzira Denise Hertzog Silva (ABADHS
Identification of novel genes and proteoforms in Angiostrongylus costaricensis through a proteogenomic approach
RNA sequencing (RNA-Seq) and mass-spectrometry-based proteomics data are often integrated in proteogenomic studies to assist in the prediction of eukaryote genome features, such as genes, splicing, single-nucleotide (SNVs), and single-amino-acid variants (SAAVs). Most genomes of parasite nematodes are draft versions that lack transcript- and protein-level information and whose gene annotations rely only on computational predictions
Synchronous down-modulation of miR-17 family members is an early causative event in the retinal angiogenic switch
Six members of the microRNA-17 (miR-17) family were mapped to three different chromosomes, although they share the same seed sequence and are predicted to target common genes, among which are those encoding hypoxia-inducible factor-1α (HIF1A) and VEGFA. Here, we evaluated the in vivo expression profile of the miR-17 family in the murine retinopathy of prematurity (ROP) model, whereby Vegfa expression is highly enhanced at the early stage of retinal neovascularization, and we found simultaneous reduction of all miR-17 family members at this stage. Using gene reporter assays, we observed binding of these miRs to specific sites in the 3′ UTRs of Hif1a and Vegfa. Furthermore, overexpression of these miRs decreased HIF1A and VEGFA expression in vitro. Our data indicate that this miR-17 family elicits a regulatory synergistic down-regulation of Hif1a and Vegfa expression in this biological model. We propose the existence of a coordinated regulatory network, in which diverse miRs are synchronously regulated to target the Hif1a transcription factor, which in turn, potentiates and reinforces the regulatory effects of the miRs on Vegfa to trigger and sustain a significant physiological response
Dysregulation of Transcription Factor Networks Unveils Different Pathways in Human Papillomavirus 16-Positive Squamous Cell Carcinoma and Adenocarcinoma of the Uterine Cervix
Squamous cell carcinoma (SCC) and adenocarcinoma (ADC) are the most common
histological types of cervical cancer (CC). The worse prognosis of ADC cases highlights
the need for better molecular characterization regarding differences between these
CC types. RNA-Seq analysis of seven SCC and three ADC human papillomavirus
16-positive samples and the comparison with public data from non-tumoral human
papillomavirus-negative cervical tissue samples revealed pathways exclusive to each
histological type, such as the epithelial maintenance in SCC and the maturity-onset
diabetes of the young (MODY) pathway in ADC. The transcriptional regulatory network
analysis of cervical SCC samples unveiled a set of six transcription factor (TF) genes
with the potential to positively regulate long non-coding RNA genes DSG1-AS1,
CALML3-AS1, IGFL2-AS1, and TINCR. Additional analysis revealed a set of MODY TFs
regulated in the sequence predicted to be repressed bymiR-96-5p ormiR-28-3p in ADC.
These microRNAs were previously described to target LINC02381, which was predicted
to be positively regulated by two MODY TFs upregulated in cervical ADC. Therefore, we
hypothesize LINC02381might act by decreasing the levels ofmiR-96-5p andmiR-28-3p,
promoting the MODY activation in cervical ADC. The novel TF networks here described
should be explored for the development of more efficient diagnostic tools
Rare genetic variants involved in multisystem inflammatory syndrome in children: a multicenter Brazilian cohort study
IntroductionDespite the existing data on the Multisystem Inflammatory Syndrome in Children (MIS-C), the factors that determine these patients evolution remain elusive. Answers may lie, at least in part, in genetics. It is currently under investigation that MIS-C patients may have an underlying innate error of immunity (IEI), whether of monogenic, digenic, or even oligogenic origin.MethodsTo further investigate this hypothesis, 30 patients with MIS-C were submitted to whole exome sequencing. ResultsAnalyses of genes associated with MIS-C, MIS-A, severe covid-19, and Kawasaki disease identified twenty-nine patients with rare potentially damaging variants (50 variants were identified in 38 different genes), including those previously described in IFNA21 and IFIH1 genes, new variants in genes previously described in MIS-C patients (KMT2D, CFB, and PRF1), and variants in genes newly associated to MIS-C such as APOL1, TNFRSF13B, and G6PD. In addition, gene ontology enrichment pointed to the involvement of thirteen major pathways, including complement system, hematopoiesis, immune system development, and type II interferon signaling, that were not yet reported in MIS-C.DiscussionThese data strongly indicate that different gene families may favor MIS- C development. Larger cohort studies with healthy controls and other omics approaches, such as proteomics and RNAseq, will be precious to better understanding the disease dynamics
Diversity in architecture and gene expression: a quantitative analysis of Exon shuffling and alternative splicing
A função e a arquitetura dos genes está começando a ser elucidada a partir do estudo de genomas completos tanto de procariotos como de eucariotos. Diversos estudos foram ultimamente realizados a respeito de exon shuffling do ponto de vista evolutivo, fenômeno relacionado à origem de novos genes através de recombinações de DNA mediadas por introns. Apesar de eventos de exon shuffling serem responsáveis pelo aumento da modularidade gênica, outros processos foram desenvolvidos ao longo da evolução para que houvesse o aumento da diversidade do proteoma sem a conseqüente expansão dos genomas, sendo splicing alternativo um dos mais freqüentes. Apresentamos nesta dissertação duas extensivas análises: 1) a análise de uma base de dados de genes eucarióticos contendo pelo menos um intron que apresentou excesso de introns de fase 0 e exons simétricos, dados que suportam exon shuffling como um importante mecanismo de evolução gênica. Avaliamos também a confiabilidade de introns preditos por programas de computador através de alinhamento de ESTs; e 2) a análise do uso alternativo de exons (UAE), um tipo de splicing alternativo, em transcritos humanos detectando que cerca de 51% dos genes humanos possuem mais de uma variante de splicing e que este tipo de processamento pós-transcricional parece ser mais freqüentemente encontrado em tecidos tumorais.Abstract not available
Diversity in architecture and gene expression: a quantitative analysis of Exon shuffling and alternative splicing
A função e a arquitetura dos genes está começando a ser elucidada a partir do estudo de genomas completos tanto de procariotos como de eucariotos. Diversos estudos foram ultimamente realizados a respeito de exon shuffling do ponto de vista evolutivo, fenômeno relacionado à origem de novos genes através de recombinações de DNA mediadas por introns. Apesar de eventos de exon shuffling serem responsáveis pelo aumento da modularidade gênica, outros processos foram desenvolvidos ao longo da evolução para que houvesse o aumento da diversidade do proteoma sem a conseqüente expansão dos genomas, sendo splicing alternativo um dos mais freqüentes. Apresentamos nesta dissertação duas extensivas análises: 1) a análise de uma base de dados de genes eucarióticos contendo pelo menos um intron que apresentou excesso de introns de fase 0 e exons simétricos, dados que suportam exon shuffling como um importante mecanismo de evolução gênica. Avaliamos também a confiabilidade de introns preditos por programas de computador através de alinhamento de ESTs; e 2) a análise do uso alternativo de exons (UAE), um tipo de splicing alternativo, em transcritos humanos detectando que cerca de 51% dos genes humanos possuem mais de uma variante de splicing e que este tipo de processamento pós-transcricional parece ser mais freqüentemente encontrado em tecidos tumorais.Abstract not available