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Biology subjects

Silva, M.

Publications and source records attributed to Silva, M..

72 records · Page 4Linked to original sources

iEC7871 Quercus suber model: the first multi-tissue diel cycle genome-scale metabolic model of a woody tree

In the last decade, genome-scale metabolic models have been increasingly used to study plant metabolic behavior at the tissue and multi-tissue level under different environmental conditions. Quercus suber, also known as the cork oak tree, is one of the most important forest communities of the Mediterranean/Iberian region. In this work, we present the genome-scale metabolic model of the Q. suber (iEC7871), the first of a woody plant. The metabolic model comprises 7871 genes, 6231 reactions, and 6481 metabolites across eight compartments. Transcriptomics data was integrated into the model to obtain tissue-specific models for the leaf, inner bark, and phellogen, with specific biomass compositions. The tissue-specific models were merged into a diel multi-tissue metabolic model to predict interactions among the three tissues at the light and dark phases. The metabolic models were also used to analyze the pathways associated with the synthesis of suberin monomers. Nevertheless, the models developed in this work can provide insights into other aspects of the metabolism of Q. suber, such as its secondary metabolism and cork formation.

systems biology↗

Engineered SARS-CoV-2 receptor binding domain improves immunogenicity in mice and elicits protective immunity in hamsters

Global containment of COVID-19 still requires accessible and affordable vaccines for low- and middle-income countries (LMICs).1 Recently approved vaccines provide needed interventions, albeit at prices that may limit their global access.2 Subunit vaccines based on recombinant proteins are suited for large-volume microbial manufacturing to yield billions of doses annually, minimizing their manufacturing costs.3 These types of vaccines are well-established, proven interventions with multiple safe and efficacious commercial examples.4-6 Many vaccine candidates of this type for SARS-CoV-2 rely on sequences containing the receptor-binding domain (RBD), which mediates viral entry to cells via ACE2.7,8 Here we report an engineered sequence variant of RBD that exhibits high-yield manufacturability, high-affinity binding to ACE2, and enhanced immunogenicity after a single dose in mice compared to the Wuhan-Hu-1 variant used in current vaccines. Antibodies raised against the engineered protein exhibited heterotypic binding to the RBD from two recently reported SARS-CoV-2 variants of concern (501Y.V1/V2). Presentation of the engineered RBD on a designed virus-like particle (VLP) also reduced weight loss in hamsters upon viral challenge.

molecular biology↗

Adaptive ecological processes and metabolic independence drive microbial colonization and resilience in the human gut

Changes in microbial community composition as a function of human health and disease states have sparked remarkable interest in the human gut microbiome. However, establishing reproducible insights into the determinants of microbial succession in disease has been a formidable challenge. Here we use fecal microbiota transplantation (FMT) as an in natura experimental model to investigate the association between metabolic independence and resilience in stressed gut environments. Our genome-resolved metagenomics survey suggests that FMT serves as an environmental filter that favors populations with higher metabolic independence, the genomes of which encode complete metabolic modules to synthesize critical metabolites, including amino acids, nucleotides, and vitamins. Interestingly, we observe higher completion of the same biosynthetic pathways in microbes enriched in IBD patients. These observations suggest a general mechanism that underlies changes in diversity in perturbed gut environments, and reveal taxon-independent markers of dysbiosis that may explain why widespread yet typically low abundance members of healthy gut microbiomes can dominate under inflammatory conditions without any causal association with disease.

microbiology↗

Disassembly of HIV envelope glycoprotein trimer immunogens is driven by antibodies elicited via immunization

Rationally designed protein subunit vaccines are being developed for a variety of viruses including influenza, RSV, SARS-CoV-2 and HIV. These vaccines are based on stabilized versions of the primary targets of neutralizing antibodies on the viral surface, namely viral fusion glycoproteins. While these immunogens display the epitopes of potent neutralizing antibodies, they also present epitopes recognized by non or weakly neutralizing ("off-target") antibodies. Using our recently developed electron microscopy epitope mapping approach, we have uncovered a phenomenon wherein off-target antibodies elicited by HIV trimer subunit vaccines cause the otherwise highly stabilized trimeric proteins to degrade into cognate protomers. Further, we show that these protomers expose an expanded suite of off-target epitopes, normally occluded inside the prefusion conformation of trimer, that subsequently elicit further off-target antibody responses. Our study provides critical insights for further improvement of HIV subunit trimer vaccines for future rounds of the iterative vaccine design process.

immunology↗

TET2 drives 5hmc marking of GATA6 and epigenetically defines pancreatic ductal adenocarcinoma transcriptional subtypes

Background and AimsPancreatic ductal adenocarcinoma (PDAC) is characterised by advanced disease stage at presentation, aggressive disease biology and resistance to therapy resulting in extremely poor five-year survival <10%. PDAC is classified into transcriptional subtypes with distinct survival characteristics, although how these arise is not known. Epigenetic deregulation, rather than genetics, has been proposed to underpin progression but exactly why is unclear and hindered by analysis of clinical samples. MethodsGenome-wide epigenetic mapping of DNA modifications 5-hydroxymethylcytosine (5mc) and 5-hydroxymethylcytosine (5hmc) using oxidative bisulphite sequencing (oxBS). Bioinformatics using iCluster and mutational profiling to identify overlap with transcriptional signatures in FFPE from resected patients and confirmation in vivo. ResultsWe find that more aggressive squamous-like PDAC subtypes result from epigenetic inactivation of loci including GATA6 that promote differentiated classical-pancreatic subtypes. We show that squamous-like PDAC transcriptional subtypes are associated with greater loss of 5hmc due to reduced expression of the 5mc-hydroxylase TET2. Furthermore, we find that SMAD4 directly supports TET2 levels in the pancreas and classical-pancreatic tumors and loss of SMAD4 expression is associated reduced 5hmc, GATA6 and squamous-like tumors. Importantly, enhancing TET2 stability using Metformin and VitaminC/ascorbic acid (AA) restores 5hmc and GATA6 levels, reverting squamous-like tumor phenotypes and WNT-dependence in vitro and in vivo. ConclusionsWe identify epigenetic deregulation of pancreatic differentiation as an underpinning event behind the emergence of transcriptomic subtypes in PDAC. Our data shows that restoring epigenetic control increases biomarkers of classical-pancreatic tumors and raises the possibility that combination of Vitamin C and Metformin may prolong survival in patients with squamous-like pancreatic cancer.

cancer biology↗

Feeling the beat: Temporal and spatial perception of heartbeat sensations

The majority of interoceptive tasks (i.e. measuring the sensitivity to bodily signals) are based upon the heartbeat sensations perception. However, temporal perception of heartbeats varies among individuals and confidence and spatial perception of heartbeats in relation to temporal judgements have not yet been systematically investigated. This study examined the perception of heartbeat sensations in both time and spatial domains, using a multi-interval heartbeat discrimination task. The relationship between these domains was investigated, as well as the contribution of mental health conditions and cardiovascular parameters. Heartbeat sensations occurred on average ~250ms after the ECG R-wave and were more frequently sampled from the left part of the chest. Participants confidence in their experience of heartbeat sensations was maximal for the 0 ms interval. Interestingly, higher confidence was related to reduced dispersion of sampling locations but we found evidence toward the absence of relationship between temporal and spatial heartbeat sensations perception, using Bayesian statistics. Finally, we found evidence toward a relationship between spatial precision of heartbeat sensations and state anxiety score, which seems independent from the cardiovascular parameters. This systematic investigation of heartbeat sensations perception provides important fresh insights, informing the mechanistic understanding of the interoceptive signaling contribution to emotion, cognition and behaviour.

neuroscience↗

Immune responses in pancreatic cancer may be restricted byprevalence of activated regulatory T-cells, dysfunctionalCD8+ T-cells, and senescent T-cells

Pancreatic cancer has the worst prognosis of any human malignancy and leukocyte infiltration is a major prognostic marker of the disease. As current immunotherapies confer negligible survival benefits, there is a need to better characterise leukocytes in pancreatic cancer to identify better therapeutic strategies. In this study, we analysed 32 human pancreatic cancer patients from two independent cohorts. A multi-parameter mass-cytometry analysis was performed on 32,000 T-cells from eight patients. Single-cell RNA sequencing dataset analysis was performed on a cohort of 24 patients. Multiplex immunohistochemistry imaging and spatial analysis were performed to map immune infiltration into the tumour microenvironment. Regulatory T-cell populations demonstrated highly immunosuppressive states with high TIGIT, ICOS and CD39 expression. CD8+ T-cells were found to be either in senescence or an exhausted state. The exhausted CD8 T-cells had low PD-1 expression but high TIGIT and CD39 expression. These findings were corroborated in an independent pancreatic cancer single-cell RNA dataset from additional 24 patients. These data suggest that T-cells are major players in the suppressive microenvironment of pancreatic cancer. Our work identifies novel therapeutic targets that should form the basis for rational design of a new generation of clinical trials in pancreatic ductal adenocarcinoma.

immunology↗

Evidence of shifts towards neural states of stability during the retrieval of real-life episodic memories

How does one retrieve real-life episodic memories? Here, we tested the hypothesis, derived from computational models, that successful retrieval relies on neural dynamics patterns that rapidly shift towards stable states. We implemented cross-temporal correlation analysis of electroencephalographic (EEG) recordings while participants retrieved episodic memories cued by pictures collected with a wearable camera depicting real-life episodes taking place at "home" and at "the office". We found that the retrieval of real-life episodic memories is supported by rapid shift towards brain states of stable activity, that the degree of neural stability is associated with the participants ability to recollect the episodic content cued by the picture, and that each individual elicits stable EEG patterns that were not shared with other participants. These results indicate that the retrieval of autobiographical memory episodes is supported by rapid shifts of neural activity towards stable states.

neuroscience↗

Macrofaunal Diversity and Community Structure of the DeSoto Canyon and Adjacent Slope

Macrofauna within the DeSoto Canyon, northern Gulf of Mexico (GOM), along the canyon wall and axis, and on the adjacent slope, were sampled along with sediment, terrain, and water mass parameters. Within the canyon, abundance and species richness decreased with depth, while evenness increased. Cluster analysis identified three depth-related groups within the canyon that conformed to previously established bathymetric boundaries: stations at 464 - 485 m, 669 - 1834 m, and > 2000 m. Abundance differed between depth groups. Species richness was lowest for the deepest group and evenness was lowest for the shallowest. Community structure within the canyon most related to fluorometry and oxygen saturation, combined with any of salinity, particulate organic carbon, sediment organic carbon, or slope. Canyon wall abundances were higher than the canyon axis or adjacent slope. Community structure differed between all three habitat types. Ordination of community structure suggests a longitudinal pattern that potentially tracks with increasing sea-surface chlorophyll that occurs in the eastward direction across the northern GOM. Canyon and slope differences may result from seasonal water masses entrained by canyon topography characterized by high salinity, oxygen saturation, fluorometry, and turbidity. Higher fluorescence and turbidity in the canyon did not translate into higher sediment organic matter. Flushing along canyon wall channels and the canyon axis may explain the low organic matter. Differences in abundance and structure between the canyon wall and axis may result from microhabitat heterogeneity due to potential hydrocarbon seepage, organically enriched sediment deposits along channels, or remnant influence from the Deepwater Horizon blowout.

ecology↗

LRP5-deficiency in OsxCreERT2 mice models intervertebral disc degeneration by aging and compression

Osterix is a critical transcription factor of mesenchymal stem cell fate, where its loss or loss of WNT signaling diverts differentiation to a chondrocytic lineage. Intervertebral disc (IVD) degeneration activates differentiation of prehypertrophic chondrocyte-like cells and inactivates WNT signaling, but its interacting role with osterix is unclear. First, compared to young-adult (5mo), mechanical compression of old (18mo) IVD induced greater IVD degeneration. Aging (5 vs 12mo) and/or compression reduced the transcription of osterix and notochordal marker T by 40-75%. Compression elevated transcription of hypertrophic chondrocyte marker MMP13 and pre-osterix transcription factor RUNX2, but less so in 12mo IVD. Next, using an Ai9/td reporter and immunohistochemistry, annulus fibrosus and nucleus pulposus cells of 5mo IVD expressed osterix, but aging and compression reduced its expression. Lastly, in vivo LRP5-deficiency in osterix-expressing cells degenerated the IVD, inactivated WNT signaling, reduced the biomechanical properties by 45-70%, and reduced transcription of osterix, notochordal markers and chondrocytic markers by 60-80%. Overall, these data indicate that age-related inactivation of WNT signaling in osterix-expressing cells may limit regeneration by depleting progenitors and attenuating the expansion of chondrocyte-like cells.

bioengineering↗

A ciliary BBSome-ARL-6-PDE6D pathway trafficks RAB-28, a negative regulator of extracellular vesicle biogenesis

Cilia both receive and send information, the latter in the form of extracellular vesicles (EVs). EVs are nano-communication devices that cells shed to influence cell, tissue, and organism behavior. Mechanisms driving ciliary EV biogenesis and environment release are almost entirely unknown. Here, we show that the ciliary G-protein RAB28, associated with human autosomal recessive cone-rod dystrophy, negatively regulates EV levels in the sensory organs of Caenorhabditis elegans. We also find that sequential targeting of lipidated RAB28 to periciliary and ciliary membranes is highly dependent on the BBSome and PDE6D, respectively, and that BBSome loss causes excessive and ectopic EV production. Our data indicate that RAB28 and the BBSome are key in vivo regulators of EV production at the periciliary membrane. Our findings also suggest that EVs control sensory organ homeostasis by mediating communication between ciliated neurons and glia, and that defects in ciliary EV biogenesis may contribute to human ciliopathies.

cell biology↗

Cell numbers, distribution, shape, and regional variation throughout the murine hippocampal formation from the adult brain Allen Reference Atlas

Quantifying the distribution of cells in every brain region is fundamental to attaining a comprehensive census of distinct neuronal and glial types. Until recently, estimating neuron numbers involved time-consuming procedures that were practically limited to stereological sampling. Progress in open-source image recognition software, growth in computing power, and unprecedented neuroinformatics developments now offer the potentially paradigm-shifting alternative of comprehensive cell-by-cell analysis in an entire brain region. The Allen Brain Atlas provides free digital access to complete series of raw Nissl-stained histological section images along with regional delineations. Automated cell segmentation of these data enables reliable and reproducible high-throughput quantification of regional variations in cell count, density, size, and shape at whole-system scale. While this strategy is directly applicable to any regions of the mouse brain, we first deploy it here on the closed-loop circuit of the hippocampal formation: the medial and lateral entorhinal cortices; dentate gyrus (DG); areas Cornu Ammonis 3 (CA3), CA2, and CA1; and dorsal and ventral subiculum. Using two independent image processing pipelines and the adult mouse reference atlas, we report the first cellular-level soma segmentation in every sub-region and layer of the left hippocampal formation through the full rostral-caudal extent, except for the (already well characterized) principal layers of CA and DG. The overall numbers ([~]600k cells in entorhinal cortex, [~]200k in DG, [~]430k in CA1-3, and [~]290k in subiculum) are corroborated by traditional stereological sampling on a data subset and well match sparse published reports.

neuroscience↗

Rapid memory reactivation at movie event boundaries promotes episodic encoding

Segmentation of continuous experience into discrete events is driven by rapid fluctuations in encoding stability at context shifts (i.e., event boundaries), yet the mechanisms underlying the online formation of event memories are poorly understood. We investigated the neural spatiotemporal similarity patterns of the scalp electrophysiological (EEG) activity of 30 participants watching a 50 min movie and found that event boundaries triggered rapid reinstatement of the just-encoded movie event EEG patterns. We also found that the onset of memory reinstatement at boundary onset (around 1500ms) was preceded by an N400-like ERP component, which likely reflects the detection of a context switch between the current and just-encoded event. A data-driven approach based on Hidden Markov Modeling allowed us to detect event boundaries as shifts between stable patterns of brain EEG activity during encoding and identify their reactivation during a free recall task. These results provide the first neurophysiological underpinnings for how the memory system segments a continuous stream of experience into episodic events.

neuroscience↗

How Public Transport affected the Propagation of Zika and Microcephaly within Rio de Janeiro early in 2015

From mid-2015 to the end of January 2016, 47 cases of microcephaly were observed in the city of Rio de Janeiro, that were not due to other viral infections (syphilis, toxoplasmosis, herpes & cytomegalovirus). These children were conceived from Dec 2014 to April 2015, far too early to be explained by the officially recorded cases from October 2015 onward. Zika must have been rampant in the city from late 2014 onward. In the first half of the paper we study how the geographic spread of microcephaly cases evolved from mid-2015 to January 2016 (and hence Zika 6-9 months earlier). Cases were not evenly spread in proportion to the number of births; they were preferentially located in the northern suburbs apparently following the public transport routes, with virtually no cases in favelas and none in the southern suburbs (Zona Sul). One key difference between the transport systems in the northern and southern suburbs is that the metro & rail system in the north is above ground in the north whereas in the southern part the metro is underground with air-conditioning in carriages and forced ventilation on the platforms. The train system does not extend to Zona Sul.\n\nIn the second half of the paper we postulate that the air-conditioning and ventilation prevent mosquitos from biting people who are waiting on platforms in Zona Sul. Agent-based simulations are used to test this hypothesis. After confirming this, we postulate that providing air-conditioning and/or forced ventilation on the rail-metro transport hub in the city center (Centro) would significantly delay the propagation of arboviruses in the city, possibly preventing epidemics. One advantage of this proposal is that it does not require the use of insecticides.

epidemiology↗

Quantifying Seasonal and Diel Variation in Anopheline and Culex Human Biting Rates in Southern Ecuador

BackgroundQuantifying mosquito biting rates for specific locations enables estimation of mosquito-borne disease risk, and can inform intervention efforts. Measuring biting itself is fraught with ethical concerns, so the landing rate of mosquitoes on humans is often used as a proxy measure. Southern coastal Ecuador was historically endemic for malaria (P. falciparum and P. vivax), although successful control efforts in the 2000s eliminated autochthonous transmission (since 2011). This study presents an analysis of data collected during the elimination period.\n\nMethodsWe examined human landing catch (HLC) data for three mosquito taxa: 2 malaria vectors, Anopheles albimanus and Anopheles punctimacula, and grouped Culex spp. These data were collected by the National Vector Control Service of the Ministry of Health over a 5-year time span (2007 - 2012) in five cities in southern coastal Ecuador, at multiple households, in all months of the year, during dusk-dawn (18:00-6:00) hours, often at both indoor and outdoor locations. Hurdle models were used to determine if biting activity was fundamentally different for the three taxa, and to identify spatial and temporal factors influencing bite rate. Due to the many different approaches to studying and quantifying bite rates in the literature, we also created a glossary of terms, to facilitate comparative studies in the future.\n\nResultsBiting trends varied significantly with species and time. All taxa exhibited exophagic feeding behavior, and outdoor locations increased both the odds and incidence of bites across taxa. An. albimanus was most frequently observed biting, with an average of 4.7 bites per hour. The highest and lowest respective months for significant biting activity were March and July for An. albimanus, July and August for An. punctimacula, and February and July for Culex spp.\n\nConclusionsFine-scale spatial and temporal differences exist in biting patterns among mosquito taxa in southern coastal Ecuador. This analysis provides detailed information for targeting vector control and household level behavioral interventions. These data were collected as part of routine vector surveillance conducted by the Ministry of Health, but such data have not been collected since. Reinstating such surveillance measures would provide important information to aid in preventing malaria re-emergence.

epidemiology↗

chewBBACA: A complete suite for gene-by-gene schema creation and strain identification

Gene-by-gene approaches are becoming increasingly popular in bacterial genomic epidemiology and outbreak detection. However, there is a lack of open-source scalable software for schema definition and allele calling for these methodologies. The chewBBACA suite was designed to assist users in the creation and evaluation of novel whole-genome or core-genome gene-by-gene typing schemas and subsequent allele calling in bacterial strains of interest. The software can run in a laptop or in high performance clusters making it useful for both small laboratories and large reference centers. ChewBBACA is available at https://github.com/B-UMMI/chewBBACA or as a docker image at https://hub.docker.com/r/ummidock/chewbbaca/.\n\nDATA SUMMARYO_LIAssembled genomes used for the tutorial were downloaded from NCBI in August 2016 by selecting those submitted as Streptococcus agalactiae taxon or sub-taxa. All the assemblies have been deposited as a zip file in FigShare (https://figshare.com/s/9cbe1d422805db54cd52), where a file with the original ftp link for each NCBI directory is also available.\nC_LIO_LICode for the chewBBACA suite is available at https://github.com/B-UMMI/chewBBACA while the tutorial example is found at https://github.com/B-UMMI/chewBBACA_tutorial.\nC_LI\n\nI/We confirm all supporting data, code and protocols have been provided within the article or through supplementary data files. {boxtimes}\n\nIMPACT STATEMENTThe chewBBACA software offers a computational solution for the creation, evaluation and use of whole genome (wg) and core genome (cg) multilocus sequence typing (MLST) schemas. It allows researchers to develop wg/cgMLST schemes for any bacterial species from a set of genomes of interest. The alleles identified by chewBBACA correspond to potential coding sequences, possibly offering insights into the correspondence between the genetic variability identified and phenotypic variability. The software performs allele calling in a matter of seconds to minutes per strain in a laptop but is easily scalable for the analysis of large datasets of hundreds of thousands of strains using multiprocessing options. The chewBBACA software thus provides an efficient and freely available open source solution for gene-by-gene methods. Moreover, the ability to perform these tasks locally is desirable when the submission of raw data to a central repository or web services is hindered by data protection policies or ethical or legal concerns.

bioinformatics↗

Case-control study highlights a different gut microbiome in cirrhotic patients with and without hepatocellular carcinoma

BackgroundNo specific microbiome in patients with hepatocellular carcinoma (HCC) has been reported to date.\n\nAimTo compare the gut microbiome found in cirrhotic patients with and without HCC.\n\nMethodsFrom 407 patients with Child Pugh A/B cirrhosis prospectively followed, 25 with HCC (cases) were matched with 25 without HCC (wo-HCC) in a 1:1 ratio according to age, gender, etiology, Child Pugh and severity of portal hypertension. In addition results were also compared with 25 healthy subjects. Faecal stool samples were collected noninvasively, aliquoted for DNA extraction and sequenced for the V3-V4 region of the microbial 16S rRNA (Illumina MiSeq Platform).\n\nResultsThere were no significant clinical differences among cases and controls. We found a differential abundance in family members of Firmicutes with a 3-fold increased of Erysipelotrichaceae and a 5-fold decrease in family Leuconostocaceae in HCC when compared to wo-HCC controls. Genus Fusobacterium was found 5-fold decreased in HCC versus wo-HCC. The ratio bacteriodes/prevotella was increased in HCC due to the significant decrease in the genus prevotella. Genus Odoribacter and Butyricimonas were more differentialy abundant in HCC. This pattern has been previously associated with an inflammatory milieu with a putative increased activation of NOD-like receptor signalling pathways. A Random Forest model trained with differential abundant taxa correctly classifyed HCC individuals with an error of 22%.\n\nConclusionsA pattern of microbiome linked to inflammation was observed in cirrhotic patients with HCC. These findings open the discussion whether or not microbiota has a physiopathologic role in HCC development in cirrhosis.

cancer biology↗

The high burden of dengue and chikungunya in southern coastal Ecuador: Epidemiology, clinical presentation, and phylogenetics from a prospective study in Machala in 2014 and 2015

Here we report the findings from the first two years of an arbovirus surveillance study conducted in Machala, Ecuador, a dengue endemic region (2014-2015). Patients with suspected dengue virus (DENV) infections (index cases, n=324) were referred from five Ministry of Health clinical sites. A subset of DENV positive index cases (n = 44) were selected, and individuals from the index household and four neighboring homes within 200-meters were recruited (n = 400). Individuals who entered the study, other than index cases, are referred to as associates. In 2014, 70.9% of index cases and 35.6% of associates had acute or recent DENV infections. In 2015, 28.3% of index cases and 12.8% of associates had acute or recent DENV infections. For every DENV infection captured by passive surveillance, we detected an additional three acute or recent DENV infections in associates. Of associates with acute DENV infections, 68% reported dengue-like symptoms, with the highest prevalence of symptomatic acute infections in children under 10 years of age. The first chikungunya virus (CHIKV) infections were detected on epidemiological week 12 in 2015. 43.1% of index cases and 3.5% of associates had acute CHIKV infections. No Zika virus infections were detected. Phylogenetic analyses of isolates of DENV from 2014 revealed genetic relatedness and shared ancestry of DENV1, DENV2 and DENV4 genomes from Ecuador with those from Venezuela and Colombia, indicating presence of viral flow between Ecuador and surrounding countries. Enhanced surveillance studies, such as this, provide high-resolution data on symptomatic and inapparent infections across the population.

epidemiology↗