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Publicações

Publicações por Nuno Fonseca

2014

RNA-Seq Gene Profiling - A Systematic Empirical Comparison

Autores
Fonseca, NA; Marioni, J; Brazma, A;

Publicação
PLOS ONE

Abstract
Accurately quantifying gene expression levels is a key goal of experiments using RNA-sequencing to assay the transcriptome. This typically requires aligning the short reads generated to the genome or transcriptome before quantifying expression of pre-defined sets of genes. Differences in the alignment/quantification tools can have a major effect upon the expression levels found with important consequences for biological interpretation. Here we address two main issues: do different analysis pipelines affect the gene expression levels inferred from RNA-seq data? And, how close are the expression levels inferred to the "true" expression levels? We evaluate fifty gene profiling pipelines in experimental and simulated data sets with different characteristics (e. g, read length and sequencing depth). In the absence of knowledge of the 'ground truth' in real RNAseq data sets, we used simulated data to assess the differences between the "true" expression and those reconstructed by the analysis pipelines. Even though this approach does not take into account all known biases present in RNAseq data, it still allows to estimate the accuracy of the gene expression values inferred by different analysis pipelines. The results show that i) overall there is a high correlation between the expression levels inferred by the best pipelines and the true quantification values; ii) the error in the estimated gene expression values can vary considerably across genes; and iii) a small set of genes have expression estimates with consistently high error (across data sets and methods). Finally, although the mapping software is important, the quantification method makes a greater difference to the results.

2014

Long-range enhancers regulating Myc expression are required for normal facial morphogenesis

Autores
Uslu, VV; Petretich, M; Ruf, S; Langenfeld, K; Fonseca, NA; Marioni, JC; Spitz, F;

Publicação
NATURE GENETICS

Abstract
Cleft lip with or without cleft palate (CL/P) is one of the most common congenital malformations observed in humans, with 1 occurrence in every 500-1,000 births(1,2). A 640-kb noncoding interval at 8q24 has been associated with increased risk of non-syndromic CL/P in humans(3-5), but the genes and pathways involved in this genetic susceptibility have remained elusive. Using a large series of rearrangements engineered over the syntenic mouse region, we show that this interval contains very remote cis-acting enhancers that control Myc expression in the developing face. Deletion of this interval leads to mild alteration of facial morphology in mice and, sporadically, to CUP. At the molecular level, we identify misexpression of several downstream genes, highlighting combined impact on the craniofacial developmental network and the general metabolic capacity of cells contributing to the future upper lip. This dual molecular etiology may account for the prominent influence of variants in the 8q24 region on human facial dysmorphologies.

2018

Gramene 2018: unifying comparative genomics and pathway resources for plant research

Autores
Tello Ruiz, MK; Naithani, S; Stein, JC; Gupta, P; Campbell, M; Olson, A; Wei, S; Preece, J; Geniza, MJ; Jiao, Y; Lee, YK; Wang, B; Mulvaney, J; Chougule, K; Elser, J; Bader, NA; Kumari, S; Thomason, J; Kumar, V; Bolser, DM; Naamati, G; Tapanari, E; Fonseca, NA; Huerta, L; Iqbal, H; Keays, M; Pomer Fuentes, AM; Tang, YA; Fabregat, A; D'Eustachio, P; Weiser, J; Stein, LD; Petryszak, R; Papatheodorou, I; Kersey, PJ; Lockhart, P; Taylor, C; Jaiswal, P; Ware, D;

Publicação
Nucleic Acids Research

Abstract

2018

Inferences on specificity recognition at the Malusxdomestica gametophytic self-incompatibility system

Autores
Pratas, MI; Aguiar, B; Vieira, J; Nunes, V; Teixeira, V; Fonseca, NA; Iezzoni, A; van Nocker, S; Vieira, CP;

Publicação
SCIENTIFIC REPORTS

Abstract
In Malus x domestica (Rosaceae) the product of each SFBB gene (the pollen component of the gametophytic self-incompatibility (GSI) system) of a S-haplotype (the combination of pistil and pollen genes that are linked) interacts with a sub-set of non-self S-RNases (the pistil component), but not with the self S-RNase. To understand how the Malus GSI system works, we identified 24 SFBB genes expressed in anthers, and determined their gene sequence in nine M. domestica cultivars. Expression of these SFBBs was not detected in the petal, sepal, filament, receptacle, style, stigma, ovary or young leaf. For all SFBBs (except SFBB15), identical sequences were obtained only in cultivars having the same S-RNase. Linkage with a particular S-RNase was further established using the progeny of three crosses. Such data is needed to understand how other genes not involved in GSI are affected by the S-locus region. To classify SFBBs specificity, the amino acids under positive selection obtained when performing intra-haplotypic analyses were used. Using this information and the previously identified S-RNase positively selected amino acid sites, inferences are made on the S-RNase amino acid properties (hydrophobicity, aromatic, aliphatic, polarity, and size), at these positions, that are critical features for GSI specificity determination.

2020

Gastric Microbiome Diversities in Gastric Cancer Patients from Europe and Asia Mimic the Human Population Structure and Are Partly Driven by Microbiome Quantitative Trait Loci

Autores
Cavadas, B; Camacho, R; Ferreira, JC; Ferreira, RM; Figueiredo, C; Brazma, A; Fonseca, NA; Pereira, L;

Publicação
MICROORGANISMS

Abstract
The human gastrointestinal tract harbors approximately 100 trillion microorganisms with different microbial compositions across geographic locations. In this work, we used RNASeq data from stomach samples of non-disease (164 individuals from European ancestry) and gastric cancer patients (137 from Europe and Asia) from public databases. Although these data were intended to characterize the human expression profiles, they allowed for a reliable inference of the microbiome composition, as confirmed from measures such as the genus coverage, richness and evenness. The microbiome diversity (weighted UniFrac distances) in gastric cancer mimics host diversity across the world, with European gastric microbiome profiles clustering together, distinct from Asian ones. Despite the confirmed loss of microbiome diversity from a healthy status to a cancer status, the structured profile was still recognized in the disease condition. In concordance with the parallel host-bacteria population structure, we found 16 human loci (non-synonymous variants) in the European-descendent cohorts that were significantly associated with specific genera abundance. These microbiome quantitative trait loci display heterogeneity between population groups, being mainly linked to the immune system or cellular features that may play a role in enabling microbe colonization and inflammation.

2020

Pan-cancer analysis of whole genomes

Autores
The ICGC/TCGA Pan-Cancer Analysis of Whole Genomes Consortium,;

Publicação
NATURE

Abstract
Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).

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