Biology subjects

Verissimo, A.

Publications and source records attributed to Verissimo, A..

13 recordsLinked to original sources

bioRxiv2026

Cartilaginous fish inform the lineage-specific evolution and MHC association of the TLR family

Chondrichthyans (sharks, rays and chimaeras) diverged from other vertebrate lineages over 400 million years ago and possess fully functional innate and adaptive immune systems. They comprise over 1,200 species occupying diverse aquatic habitats, from fresh to marine waters and from shallow to deep seas. Exposure to diverse pathogens through time, together with contemporary ocean warming and habitat degradation driven by climate change, has likely shaped unique immune mechanisms in these species. Toll-like receptors (TLRs) are central components of innate immunity, recognizing conserved pathogen-associated molecular patterns and initiating immune responses, yet their diversity remains poorly characterized in Chondrichthyans. Here, we characterize the TLR gene repertoire in elasmobranchs (sharks and rays) using genomic and transcriptomic data. We identify orthologs spanning all known vertebrate TLR families, including genes shared with agnathans as well as gnathostome-specific genes, and detect lineage-specific patterns of TLR duplication and loss, particularly in squaliform sharks and rays. Molecular evolution analyses indicate that most elasmobranch TLRs are under strong purifying selection, with positively selected sites in all genes, consistent with ongoing adaptation to pathogen-and environment-driven pressures. Several TLRs co-localize with genomic regions enriched in immune genes, including MHC paralogous regions, suggesting an ancestral genomic hotspot for vertebrate immunity.

evolutionary biology↗

bioRxiv2025

Inversions Dominate Evolution in the Highly Admixed European Sardine (Sardina pilchardus)

Inversions can play key roles in the genetic architecture of adaptation, but the scale of their effects across different species remains poorly understood. Here, we use whole- genome sequencing to investigate the influence of inversions on the population genomics of the r-selected European sardine (Sardina pilchardus). Allele frequency differences from millions of SNPs across 34 populations spanning the species range were analyzed. Genomic scans identified several extreme outlier regions overlapping chromosome-scale inversions, collectively representing over half the genome. Our findings suggest these inversions are associated with locally adapted life history strategies. First, SNPs within outlier regions containing inversions exhibited striking allele frequency differences between Atlantic and Mediterranean sardines, which differ in key adaptive life history traits. In the Atlantic, inversion allele frequencies varied latitudinally, while in the Mediterranean, they shifted longitudinally, aligning with temperature and oceanographic features that influence sardine life history strategies. Moreover, adjacent populations in contrasting environments displayed pronounced allele frequency differences in inversions. These spatial patterns of allele frequencies sharply contrasted with those based on neutral loci, indicating they are driven by selection. After rigorously filtering SNPs affected by selection and inversions, sardine populations showed high admixture across their range but significant population structure and isolation by distance, especially in the Mediterranean. This study demonstrates that inversions can shape genome-wide patterns of genetic diversity and population structure in highly admixed r-selected marine species. These findings also offer crucial insights for stock delimitation and management of this commercially valuable species in the face of climate change.

genomics↗

bioRxiv2025

Freshwater fish community assessment using eDNA metabarcoding vs. capture-based methods: differences in efficiency and resolution coupled to habitat and ecology

Environmental DNA (eDNA) metabarcoding has revolutionized ecological and environmental research by describing communities without relying on direct observations, making it a powerful, non-invasive, and cost-effective tool in biodiversity monitoring. However, implementation of eDNA as a standard protocol in long-term monitoring programs, that have traditionally relied on capture-based methods, poses challenges in terms of data comparability. Here, we compared freshwater fish communities assessed through eDNA metabarcoding and electrofishing, across 35 sampling sites in the lower Tagus River basin, Portugal. For most species or species-groups analyzed individually (13 out of 17), there was a significant correspondence between electrofishing and eDNA metabarcoding detections. The correspondence was weaker when comparing the number of specimens captured by electrofishing with the number of eDNA metabarcoding reads, with seven out of 13 taxa showing significant relationships. Species richness estimates based on the two methods were very similar at the basin level. The methods yielded significantly different species compositions, although these differences were driven by samples collected in the Tagus main channel, which is wider and has higher flow rates than tributaries. Benthic and shoreline fish communities showed similar species composition in the two methods, but this was not the case for pelagic communities, probably due to the higher water turnover of the pelagic zone and electrofishing inefficiency. Our results highlight the high potential of eDNA metabarcoding as a complementary method to electrofishing for freshwater fish monitoring, though further validation is needed to assess biases related to site-specific hydrological conditions and the ecology of the target species.

ecology↗

bioRxiv2024

Improving whole biodiversity monitoring and discovery with environmental DNA metagenomics

Environmental DNA (eDNA) metagenomics sequences all DNA molecules present in environmental samples and has the potential of identifying virtually any organism from which they are derived. However, due to unacceptable levels of false positives and negatives, this approach is underexplored as a tool for biodiversity monitoring across the tree of life, particularly for non-microscopic eukaryotes. We present SEQIDIST, a framework that combines multilocus BLAST matches against several reference databases followed by analysis of sequence identity distribution patterns to disentangle false positives while revealing new biodiversity and increasing the accuracy of metagenomic approaches. We tested SEQIDIST on an eDNA metagenomic dataset from a riverine site and compare the results to those obtained with an eDNA metabarcoding approach for benchmarking purposes. We start by characterizing the biological community ([~] 2000 taxa) across the tree of life at low taxonomic levels and show that eDNA metagenomics has a higher sensitivity than eDNA metabarcoding in discovering new diversity. We show that limited representation of whole genome sequences in reference databases can lead to false positives. For non-microscopic eukaryotes, eDNA metagenomic data often consist of a few sparse, anonymous sequences scattered across the genome, making metagenome assembly methods unfeasible. Finally, we infer eDNA source and residency time using read length distributions as a measure of decay status. The higher accuracy of SEQIDIST opens the discussion of the archival potential of eDNA metagenomics and its implementation in biodiversity monitoring actions at large planetary and temporal scales.

ecology↗

bioRxiv2024

Inclusion of Salicornia ramosissima biomass in diets for juvenile whiteleg shrimp (Penaeus vannamei) induces favourable but transient effects in the immune and oxidative status

The whiteleg shrimp, Penaeus vannamei, is a highly valued and globally produced crustacean species. However, the rising cost of shrimp feed, exacerbated by increasing cereal prices, prompts the exploration of cost-effective and sustainable formulations for shrimp farming. This study investigates the potential of Salicornia ramosissima, a non-edible biomass co-product, as a substitute for wheat meal in juvenile whiteleg shrimp diets, aiming to create economically and ecologically sound formulations. The present study aimed to assess the impact of incorporating S. ramosissima into whiteleg shrimp aquafeeds on various aspects of shrimp development, including growth performance, survival, immune status, and oxidative status. A commercial-like diet was formulated and served as control, whereas four other diets contained S. ramosissima stems or a combination of leaves and seeds, both at inclusion levels of 5% and 10%, in addition to the control diet. Whiteleg shrimps were fed the experimental diets for 31 and 55 days, followed by a bacterial bath challenge to gauge their immune response to pathogens. At the end of the feeding period, whiteleg shrimps growth performance and survival rates remained consistent across all diets. However, whiteleg shrimp fed diets with S. ramosissima inclusion consumed more feed to achieve similar weights to those fed on the control diet, particularly in diets containing leaves and seeds at a 10% inclusion level, likely due to lower digestibility of dry matter, lipids, and energy. While S. ramosissima biomass inclusion did not affect shrimp weight, relative growth rate, or survival, it did lead to higher feed conversion ratios and feed intake, suggesting differences in nutrient digestibility and metabolic utilization. Additionally, S. ramosissima inclusion affected whiteleg shrimps overall body composition, particularly moisture and ash content. Dietary S. ramosissima inclusion modulated antioxidant enzyme activity in the shrimps hepatopancreas, indicating potential health improvements. The study also observed gene expression changes related to antioxidant enzymes, indicating an overall down-regulation with the inclusion of S. ramosissima. Despite challenges in feeding efficiency, the inclusion of S. ramosissima, especially stems, shows promise in reducing feed costs by utilizing a by-product. Furthermore, S. ramosissima inclusion led to subtle changes in certain plasma humoral parameters and hepatopancreas gene expression. Although some immune parameters varied, these effects appeared to diminish over time. In conclusion, this study highlights the potential of S. ramosissima as a functional feed ingredient capable of enhancing shrimps antioxidant response, aligning with global resource optimization and sustainability initiatives.

immunology↗

bioRxiv2024

The need for high-resolution gut microbiome characterization to design efficient strategies for sustainable aquaculture production

Microbiome-directed dietary interventions such as microbiota-directed fibers (MDFs) have a proven track record in eliciting responses in beneficial gut microbes and are increasingly being promoted as an effective strategy to improve animal production systems. Here we used initial metataxonomic data on fish gut microbiomes as well as a wealth of a priori mammalian microbiome knowledge on -MOS and {beta}-mannan-derived MDFs to study effects of such feed supplements in Atlantic salmon (Salmo salar) and their hitherto poorly characterized gut microbiomes. Our multi-omic analysis revealed that the investigated MDFs (two -mannans and an acetylated {beta}-galactoglucomannan), at a dose of 0.2%, had negligible effects on both host gene expression, and gut microbiome structure and function under studied conditions. While a subsequent trial using a higher (4%) dietary inclusion of {beta}-mannan significantly shifted the gut microbiome composition, there were still no biologically relevant effects on salmon metabolism and physiology. Only a single Burkholderia-Caballeronia-Paraburkholderia (BCP) population demonstrated consistent and significant abundance shifts across both feeding trials, although with no evidence of {beta}-mannan utilization capabilities or changes in gene transcripts for producing metabolites beneficial to the host. In light of these findings, we revisited our omics data to predict and outline novel and potentially beneficial endogenous lactic acid bacteria that should be targeted with future, conceivably more suitable, MDF strategies for salmon. IMPORTANCEThis study focuses on the potential of MDFs to improve aquaculture production. Despite preliminary 16S rRNA amplicon data suggested that populations in the salmon gut microbiome could utilize structurally complex mannans, our findings indicates that endogenous microbes could not metabolize it, nor the host responds to its dietary inclusion, at least not under the trial conditions investigated in this study. We highlight that high-resolution and host-specific microbiome characterization can greatly improve trial design and selection of candidate MDFs for future nutritional interventions. Understanding the intricate interplay between host and its gut microbiome is paramount in studies seeking to leverage endogenous microbial communities to benefit the host. While each new condition, whether it is a disease onset or a nutritional stressor, has the potential to profoundly reshape the microbial diversity, composition and outputs, the functional microbiome information gained under healthy conditions represent a pivotal step towards designing more effective trials involving microbiome-reprogramming feed additives. Overall, we envisage that these results will lead to improved focus on coupling fundamental microbiome characterization to the design of next-generation feeds for salmon aquaculture.

microbiology↗

bioRxiv2021

Ocean-Warming During Embryogenesis Programs a Lasting Transcriptomic Signature in Fishes

Exposure to elevated temperatures during embryogenesis can influence the plasticity of tissues in later-life. Despite these long-term changes in plasticity, few differentially expressed genes are ever identified, suggesting that the developmental programming of later-life plasticity may occur through the modulation of other aspects of the transcriptomic architecture, such as gene network function. Here, we use network modelling approaches to demonstrate that warm temperatures during embryonic development (developmental warming) have consistent effects in later-life on the organisation of transcriptomic networks across four diverse species of fishes: Scyliorhinus canicula, Danio rerio, Dicentrarchus labrax, and Gasterosteus aculeatus. The transcriptomes of developmentally warmed fishes are characterised by an increased entropy of their pairwise gene interaction networks, implying a less structured, more random set of gene interactions. We also show that, in zebrafish subject to developmental warming, the entropy of an individual gene within a network is associated with that genes probability of expression change during temperature acclimation in later-life. However, this association is absent in animals reared under control conditions. Thus, the thermal environment experienced during embryogenesis can alter transcriptomic organisation in later-life, and these changes may influence an individuals responsiveness to future temperature challenges.

developmental biology↗

bioRxiv2021

A genome assembly of the Atlantic chub mackerel (Scomber colias): a valuable teleost fishing resource

The Atlantic chub mackerel, Scomber colias Gmelin, 1789, is a medium-size pelagic fish with substantial importance in the fisheries of the Atlantic Ocean and the Mediterranean Sea. Over the past decade, this species has gained special relevance being one of the main targets of pelagic fisheries in the NE Atlantic. Here, we sequenced and annotated the first high-quality draft genome assembly of S. colias, produced with Pacbio HiFi long reads and Illumina Paired-End short reads. The estimated genome size is 814 Mb distributed into 2,028 scaffolds and 2,093 contigs with an N50 length of 4,19 and 3,34 Mb, respectively. We annotated 27,675 protein-coding genes and the BUSCO analyses indicated high completeness, with 97.3 % of the single-copy orthologs in the Actinopterygii library profile. The present genome assembly represents a valuable resource to address the biology and management of this relevant fishery. Finally, this is the fourth high-quality genome assembly within the Order Scombriformes and the first in the genus Scomber.

genomics↗

bioRxiv2021

Force-induced changes of PilY1 drive surface sensing by Pseudomonas aeruginosa

During biofilm formation, the opportunistic pathogen Pseudomonas aeruginosa uses its type IV pili (TFP) to sense a surface, eliciting increased second messenger production and regulating target pathways required to adapt to a surface lifestyle. The mechanisms whereby TFP detect surface contact is still poorly understood, although mechanosensing is often invoked with little data supporting this claim. Using a combination of molecular genetics and single cell analysis, with biophysical, biochemical and genomics techniques we show that force-induced changes mediated by the von Willebrand A (vWA) domain-containing, TFP tip-associated protein PilY1 are required for surface sensing. Atomic force microscopy shows that PilY1 can undergo force-induced, sustained conformational changes akin to those observed for mechanosensitive proteins like titin. We show that mutation of a single cysteine residue in the vWA domain results in modestly lower surface adhesion forces, increased nanospring-like properties, as well as reduced c-di-GMP signaling and biofilm formation. Mutating this cysteine has allowed us to genetically separate TFP function in twitching from surface sensing signaling. The conservation of this Cys residue in all P. aeruginosa PA14 strains, and its absence in the ~720 sequenced strains of P. aeruginosa PAO1, could contribute to explaining the observed differences in surface colonization strategies observed for PA14 versus PAO1. ImportanceMost bacteria live on abiotic and biotic surfaces in surface-attached communities known as biofilms. Surface sensing and increased levels of the second messenger molecule c-di-GMP are crucial to the transition from planktonic to biofilm growth. The mechanism(s) underlying TFP-mediated surface detection that triggers this c-di-GMP signaling cascade are unclear. Here, we provide a key insight into this question: we show that the eukaryotic-like, vWA domain of the TFP tip-associated protein PilY1 responds to mechanical force, which in turn drives production of a key second messenger needed to regulate surface behaviors. Our studies highlight a potential mechanism that could account for differing surface colonization strategies.

microbiology↗

bioRxiv2018

A haplotype-resolved draft genome of the European sardine (Sardina pilchardus)

BackgroundThe European sardine (Sardina pilchardus Walbaum, 1792) has a high cultural and economic importance throughout its distribution. Monitoring studies of sardine populations report an alarming decrease in stocks due to overfishing and environmental change, which has resulted in historically low captures along the Iberian Atlantic coast. Consequently, there is an urgent need to better understand the causal factors of this continuing decrease in the sardine stock. Important biological and ecological features such as levels of population diversity, structure, and migratory patterns can be addressed with the development and use of genomics resources.\n\nFindingsThe sardine genome of a single female individual was sequenced using Illumina HiSeq X Ten 10X Genomics linked-reads generating 113.8 Gb of data. Three draft genomes were assembled: two haploid genomes with a total size of 935 Mbp (N50 103Kb) each, and a consensus genome with a total size of 950 Mbp (N50 97Kb). The genome completeness assessment captured 84% of Actinopterygii Benchmarking Universal Single-Copy Orthologs. To obtain a more complete analysis, the transcriptomes of eleven tissues were sequenced and used to aid the functional annotation of the genome, resulting in 40 777 genes predicted. Variant calling on nearly half of the haplotype genome resulted in the identification of more than 2.3 million phased SNPs with heterozygous loci.\n\nConclusionsA draft genome was obtained with the 10X Genomics linked-reads technology, despite a high level of sequence repeats and heterozygosity that are expected genome characteristics of a wild sardine. The reference sardine genome and respective variant data are a cornerstone resource of ongoing population genomics studies to be integrated into future sardine stock assessment modelling to better manage this valuable resource.

genomics↗

bioRxiv2018

Consensus outlier detection in survival analysis using the rank product test

Survival analysis is a well known technique in the medical field. The identification of individuals whose survival time is too short or to long given their profile, assumes great importance for the detection of new prognostic factors. The study of these outlying observations have gained increasing relevancy with the availability of high-throughput molecular and clinical data for large cohorts of patients. Several methods for outlier detection in survival data have been proposed, which include the analysis of the residuals, the measurement of the concordance c-index, and methods based on quantile regression for censored data. However, different results are obtained depending on the type of method used. In order to solve the disparity of results we proposed to apply the Rank Product test. A simulated dataset, and two clinical datasets were used to illustrate our proposed consensus outlier detection method, one from myeloma disease and the other from The Cancer Genome Atlas (TCGA) ovarian cancer. Finally, the Rank Product with multiple testing corrections was performed in order to identify which observations have the highest rank amongst the methods considered. Our results illustrate the potential of this consensus approach for the automated retrieval of outliers and also the identification of biomarkers associated with survival in large datasets.

bioinformatics↗

bioRxiv2018

Sparse network-based regularization for the analysis of patientomics high-dimensional survival data

Data availability by modern sequencing technologies represents a major challenge in oncological survival analysis, as the increasing amount of molecular data hampers the generation of models that are both accurate and interpretable. To tackle this problem, this work evaluates the introduction of graph centrality measures in classical sparse survival models such as the elastic net.\n\nWe explore the use of network information as part of the regularization applied to the inverse problem, obtained both by external knowledge on the features evaluated and the data themselves. A sparse solution is obtained either promoting features that are isolated from the network or, alternatively, hubs, i.e., features that are highly connected within the network.\n\nWe show that introducing the degree information of the features when inferring survival models consistently improves the model predictive performance in breast invasive carcinoma (BRCA) transcriptomic TCGA data while enhancing model interpretability. Preliminary clinical validation is performed using the Cancer Hallmarks Analytics Tool API and the String database.\n\nThese case studies are included in the recently released glmSparseNet R package1, a flexible tool to explore the potential of sparse network-based regularizers in generalized linear models for the analysis of omics data.

bioinformatics↗

bioRxiv2017

MassBlast: A workflow to accelerate RNA-seq and DNA database analysis

SummaryCurrent workflows for sequence analysis heavily depend on user input and manual curation. New specialized tools and methods are appearing all the time, but the actions required for a full analysis are disconnected and very time-consuming. The software we propose, MassBlast, combines BLAST+ and an automated workflow analysis to filter the results and significantly improve the annotation of multiple sequencing databases for exploring new biosynthetic pathways and new protein families, among other applications. MassBlast is fully configurable and reproducible.\n\nAvailability and ImplementationThe MassBlast package is written in Ruby. Source code and releases are freely available from Github (https://github.com/averissimo/mass-blast) for all major platforms (Linux, MS Windows and OS X) under the GPLv3 license.\n\nContactandre.verissimo@tecnico.ulisboa.pt

bioinformatics↗