Biology subjects

De Oliveira, R.

Publications and source records attributed to De Oliveira, R..

6 recordsLinked to original sources

bioRxiv2024

Heterogeneity of layer 4 in visual areas of rhesus macaque cortex

Non-human primates like rhesus macaques are pivotal models for decoding human visual cortex physiology and disorders. We introduce BrainSPACE, an innovative pipeline for rapid and precise brain tissue banking, to sample visual cortex areas: V1, V2, V4, MT, and TEO. Applying snRNA-seq to V1 and V4 (95,071 nuclei), we uncovered conserved GABAergic neuron profiles but stark area-specific diversity in principal neurons, featuring seven unique layer 4 subtypes in V1 and one in V4. Complementary smFISH validated transcriptional gradients across these areas, aligning with ventral and dorsal stream hierarchies. Gene ontology analyses highlighted plasticity-related pathways in unique layer 4 subtypes, with genes like NTNG1 and NLGN1 linked to neurodevelopmental disorders such as autism and schizophrenia. Our insights bridge molecular architecture to visual processing, offering an interactive atlas for community use. By revealing how layer 4 heterogeneity drives hierarchical specialization, our work advances primate brain mapping and informs therapeutic strategies for vision-related pathologies.

neuroscience↗

bioRxiv2023

METABOLIC MODELLING AS A POWERFUL TOOL TO IDENTIFY CRITICAL COMPONENTS OF THE PNEUMOCYSTIS GROWTH MEDIUM

Establishing suitable in vitro culture conditions for microorganisms is crucial for dissecting their biology and empowering potential applications. However, a significant number of bacterial and fungal species, including Pneumocystis jirovecii, remain unculturable, hampering research efforts. P. jirovecii is a deadly pathogen of humans that causes life-threatening pneumonia in immunocompromised individuals and transplant patients. Despite the major impact of Pneumocystis on human health, we remain ignorant about the pathobiology of this fungus. This is largely due to the fact that its experimental dissection has been constrained by the inability to culture the organism in vitro. We present a comprehensive in silico genome-scale metabolic model of Pneumocystis growth and metabolism, with a view to identifying metabolic requirements and imbalances that hinder growth in vitro. We utilise recently published genome data and available information in the literature as well as bioinformatics and software tools to develop and validate the model. In addition, we employ Flux Balance Analysis and Reinforcement Learning approaches to make predictions regarding metabolic fluxes and to identify critical components of the Pneumocystis growth medium. Our findings offer insights into the biology of Pneumocystis and provide a novel strategy to overcome the longstanding challenge of culturing this pathogen in vitro.

systems biology↗

bioRxiv2022

All families of transposable elements were active in the recent wheat genome evolution and polyploidy had no impact on their activity

AO_SCPLOWBSTRACTC_SCPLOWBread wheat (Triticum aestivum L.) is a major crop and its genome is one of the largest ever assembled at reference-quality level. It is 15 Gb, hexaploid, with 85% of transposable elements (TEs). Wheat genetic diversity was mainly focused on genes and little is known about the extent of genomic variability affecting TEs, transposition rate, and the impact of polyploidy. Multiple chromosome-scale assemblies are now available for bread wheat and for its tetraploid and diploid wild relatives. In this study, we computed base pair-resolved, gene-anchored, whole genome alignments of A, B, and D lineages at different ploidy levels in order to estimate the variability that affects the TE space. We used assembled genomes of 13 T. aestivum cultivars (6x=AABBDD), T. durum (4x=AABB), T. dicoccoides (4x=AABB), T. urartu (2x=AA), and Aegilops tauschii (2x=DD). We show that 5 to 34% of the TE fraction is variable, depending on the species divergence. Between 400 and 13,000 novel TE insertions per subgenome were detected. We found lineage-specific insertions for nearly all TE families in di- tetra- and hexaploids. No burst of transposition was observed and polyploidization did not trigger any boost of transposition. This study challenges the prevailing idea of wheat TE dynamics and is more in agreement with an equilibrium model of evolution.

genomics↗

bioRxiv2020

New insights into homoeologous copy number variations in the hexaploid wheat genome

Bread wheat is an allohexaploid species originating from two successive and recent rounds of hybridization between three diploid species that were very similar in terms of chromosome number, genome size, TE content, gene content and synteny. As a result, it has long been considered that most of the genes were in three pairs of homoeologous copies. However, these so-called triads represent only one half of wheat genes, while the remaining half belong to homoeologous groups with various number of copies across subgenomes. In this study, we examined and compared the distribution, conservation, function, expression and epigenetic profiles of triads with homoeologous groups having undergone a deletion (dyads) or a duplication (tetrads) in one subgenome. We show that dyads and tetrads are mostly located in distal regions and have lower expression level and breadth than triads. Moreover, they are enriched in functions related to adaptation and more associated with the repressive H3K27me3 modification. Altogether, these results suggest that triads mainly correspond to housekeeping genes and are part of the core genome, while dyads and tetrads belong to the Triticeae dispensable genome. In addition, by comparing the different categories of dyads and tetrads, we hypothesize that, unlike most of the allopolyploid species, subgenome dominance and biased fractionation are absent in hexaploid wheat. Differences observed between the three subgenomes are more likely related to two successive and ongoing waves of post-polyploid diploidization, that had impacted A and B more significantly than D, as a result of the evolutionary history of hexaploid wheat. Core ideasOnly one half of hexaploid wheat genes are in triads, i.e. in a 1:1:1 ratio across subgenomes Triads are likely part of the core genome; dyads and tetrads belong to the dispensable genome Subgenome dominance and biased fractionation are absent in hexaploid wheat Subgenome differences are related to two successive waves of post-polyploid diploidization

genomics↗

bioRxiv2018

Worldwide phylogeography and history of wheat genetic diversity

Since its domestication in the Fertile Crescent ~8,000 to 10,000 years ago, wheat has undergone a complex history of spread, adaptation and selection. To get better insights into the wheat phylogeography and genetic diversity, we describe allele distribution through time using a set of 4,506 landraces and cultivars originating from 105 different countries genotyped with a high-density SNP array. Although the genetic structure of landraces is collinear to ancient human migration roads, we observe a reshuffling through time, related to breeding programs, with the apparition of new alleles enriched with structural variations that may be the signature of introgressions from wild relatives after 1960.\n\nOne Sentence SummaryA phylogeographical study reveals the complex history of wheat genetic diversity through time and space.

genetics↗

bioRxiv2018

Impact of transposable elements on genome structure and evolution in bread wheat

BackgroundTransposable elements (TEs) are ubiquitous components of genomes and they are the main contributors to genome evolution. The reference sequence of the hexaploid bread wheat (Triticum aestivum L.) genome enabled for the first time a comprehensive genome-wide view of the dynamics of TEs that have massively proliferated in the A, B, and D subgenomes.\n\nResultsTEs represent 85% of the genome. We traced back TE amplification dynamics in the evolutionary history of wheat and did not find large bursts in the wake of either the tetra- or the hexaploidization. Despite the massive turnover of TEs since A, B, and D diverged, 76% of TE families are present in similar proportions in the three subgenomes. Moreover, spacing between homeologous genes was also conserved. TE content around genes is very different from the TE space comprising large intergenic regions and families that are enriched or depleted from gene promoters are the same in the three subgenomes.\n\nConclusionsThe chromosome-scale assembly of the wheat genome provided an unprecedented genome-wide view of the organization and impact of TEs in such a complex genome. Our results suggest that TEs play a role at the structural level and that the overall chromatin structure is likely under selection pressure.

genomics↗