Biology subjects

Mantica, F.

Publications and source records attributed to Mantica, F..

13 recordsLinked to original sources

bioRxiv2026

Alternative splicing and gene expression repurpose ancestral genes through distinct evolutionary routes

Specialized tissues often evolve by repurposing ancestral genes. Tissue-specific alternative splicing (TS-AS) and tissue-specific gene expression (TS-GE) have been proposed as complementary mechanisms contributing to tissue specialization, but whether they provide broadly interchangeable solutions or instead follow distinct, constrained evolutionary routes remains unknown. To address this question, here we compare TS-AS and TS-GE across eight homologous tissues, 20 bilaterian species and 7,178 ancestral gene families spanning 700 million years. The two mechanisms were similarly prevalent and, together, they affected nearly three-quarters of ancestral gene families across our dataset. However, they targeted largely non-overlapping gene sets within species, with contrasting architectures and functions. TS-AS usually acts on longer, exon-rich genes and modulates intracellular machinery shared across tissues, whereas TS-GE preferentially evolves in duplicated genes and impacts tissue-defining extracellular and nuclear processes. Unexpectedly, although TS-GE was globally more conserved, neural-specific splicing gains outnumbered expression gains at the origins of vertebrates and insects, revealing a prominent contribution of TS-AS to early nervous system transcriptome diversification. Exon-level orthology reconstructions further uncovered extensive recurrent evolution of neural-specific exons in the same ancestral genes across the phylogeny. Importantly, deletion of two such microexons in Drosophila negatively impacted overall fitness and led to neurological-associated phenotypes such as reduced climbing or hyperactivity. Altogether, our findings reveal distinct but complementary evolutionary routes by which gene expression and alternative splicing repurpose ancestral genes, and highlight recurrent neural exon evolution as a functionally important contributor to nervous systems.

evolutionary biology↗

bioRxiv2026

Evolutionary landscapes of zygotic genome activation across animals

During early animal embryogenesis, gene expression control shifts from maternally deposited products to newly transcribed RNA through zygotic genome activation (ZGA). Although essential and universal, ZGA remains poorly understood outside a few model species. Here, we generated a transcriptomic atlas of early embryogenesis across 61 animal species from 13 phyla and used a unified computational framework to infer ZGA timing systematically. We find extensive variation in ZGA onset across animals, but show that the ratio between genome size and egg cytoplasmic volume, a proxy for the nuclear-to-cytoplasmic ratio, robustly predicts when genome activation begins. We also reveal that zygotic genes also differ from maternal transcripts in genomic architecture, function and evolutionary conservation, suggesting that ZGA follows a conserved molecular logic despite flexible transcriptomic outputs.

evolutionary biology↗

bioRxiv2025

Translational repression of viral RNA mediates arbovirus persistence in mosquitoes

Persistent infection of mosquito cells is essential for the transmission of arboviruses, yet how these viruses produce sufficient progeny without compromising host cell fitness remains unclear. Arbovirus genomes exhibit suboptimal codon usage for both human and mosquito hosts, raising questions about how they achieve efficient translation in such distinct cellular environments. Using chikungunya virus (CHIKV) as a model, we conducted a temporal, genome-wide analysis of transcription, translation, and tRNA modifications in Aedes albopictus C6/36 cells. Unlike in human cells, CHIKV infection does not alter the tRNA modification landscape in mosquitoes to overcome codon bias, nor does it induce widespread degradation of host transcripts. Instead, viral persistence is marked by a progressive, virus-specific repression of CHIKV RNA translation, occurring alongside a recovery of host mRNA translation. This translational balance, maintained independently of the RNAi system, enables sustained viral production without major disruption to host gene expression. Our findings identify translational control as a central mechanism underlying persistent arbovirus infection in mosquito cells.

microbiology↗

bioRxiv2024

Phenotypic impact of individual conserved neuronal microexons and their master regulators in zebrafish

Microexons exhibit striking evolutionary conservation and are subject to precise, switch-like regulation in neurons, orchestrated by the splicing factors Srrm3 and Srrm4. Disruption of these regulators in mice leads to severe neurological phenotypes, and their misregulation is linked to human disease. However, the specific microexons involved in these phenotypes and the effects of individual microexon deletions on neurodevelopment, physiology, and behavior remain poorly understood. To explore this, we generated zebrafish lines with deletions of 18 individual microexons, alongside srrm3 and srrm4 mutant lines, and conducted comprehensive phenotypic analyses. We discovered that while loss of srrm3, alone or together with srrm4, resulted in significant alterations in neuritogenesis, locomotion, and social behavior, individual microexon deletions typically produced mild or no noticeable effects. Nonetheless, we identified specific microexons associated with defects in neuritogenesis (evi5b, vav2, itsn1, src) and social behavior (vti1a, kif1b). Additionally, most microexon deletions triggered coordinated transcriptomic changes in neural pathways, suggesting the presence of molecular compensatory mechanisms. Our findings suggest that the severe phenotypes caused by Srrm3/4 depletion arise from the combined effects of multiple subtle disruptions across various cellular pathways, which are individually well-tolerated.

molecular biology↗

bioRxiv2024

Evolutionary diversification of ancestral genes across vertebrates and insects

BackgroundVertebrates and insects diverged approximately 700 million years ago, and yet they retain a large core of conserved genes from their last common ancestor. These ancient genes present strong evolutionary constraints, which limit their overall sequence and expression divergence. However, these constraints can greatly vary across ancestral gene families and, in at least some cases, sequence and expression changes can have functional consequences. Importantly, overall patterns of sequence and expression divergence and their potential functional outcomes have never been explored in a genome-wide manner across large animal evolutionary distances. ResultsWe focused on approximately 7,000 highly conserved genes shared between vertebrates and insects, and we investigated global patterns of molecular diversification driven by changes in sequence and gene expression. We identified molecular features generally linked to higher or lower diversification rates, together with gene groups with similar diversification profiles in both clades. Moreover, we discovered that specific sets of genes underwent differential diversification during vertebrate and insect evolution, potentially contributing to the emergence of unique phenotypes in each clade. ConclusionsWe generated a comprehensive resource of measures of sequence and expression divergence across vertebrates and insects, which revealed a continuous spectrum of evolutionary constraints among highly conserved genes. These constraints are normally consistent between these two clades and associated with specific molecular features, but in some cases we also identified cases of lineage-specific diversification likely linked to functional evolution.

evolutionary biology↗

bioRxiv2023

A novel regulatory mechanism of actin cytoskeleton dynamics through a neural microexon in DAAM1 is necessary for memory formation

Actin cytoskeleton dynamics is critical for nervous system development and function, yet the role of alternative splicing in controlling these processes is poorly understood. A highly conserved subset of neuronal-specific microexons coordinates fundamental aspects of nervous system biology. A subset of these exons is enriched in genes involved in actin cytoskeleton, yet their functions are unknown. Here, we focus on a microexon in DAAM1, a member of the formin-homology-2 (FH2) domain class of proteins, which have diverse functions associated with the reorganization of the actin cytoskeleton. Remarkably, splicing of the microexon extends the linker region of the DAAM1 FH2 domain and leads to qualitative and quantitative changes in actin polymerization. Deletion of the microexon results in neuritogenesis defects and increased calcium influx in differentiated neurons. Moreover, mice harboring the deletion exhibit postsynaptic defects, reduced number of immature dendritic spines, impaired long-term potentiation, and deficits in memory formation. These deficits are associated with increased RHOA/ROCK signaling, pivotal in controlling actin-cytoskeleton dynamics, and were rescued by treatment with a ROCK inhibitor. We thus demonstrate that a conserved neuronal microexon in DAAM1 is critical for controlling actin dynamics through the RHOA/ROCK signaling pathway and is necessary for normal cognitive functioning.

neuroscience↗

bioRxiv2022

Pervasive evolution of tissue-specificity of ancestral genes differentially shaped vertebrates and insects

Regulation of gene expression is arguably the main mechanism contributing to tissue phenotypic diversity within and between species. Here, we assembled an extensive transcriptomic dataset covering twenty bilaterian species and eight tissues, selecting a specular phylogeny that allowed both the combined and parallel investigation of gene expression evolution between vertebrates and insects. We specifically focused on widely conserved ancestral genes, identifying strong cores of pan-bilaterian tissue-specific genes and even larger groups that diverged to define vertebrate and insect tissues. Systematic inferences of tissue-specificity gains and losses show that nearly half of all ancestral genes have been recruited into tissue-specific transcriptomes. This occurred during both ancient and, especially, recent bilaterian evolution, with several gains being associated with the emergence of unique phenotypes. Such pervasive evolution of tissue-specificity was linked to gene duplication coupled with specialization, including an unappreciated prolonged effect of whole genome duplications during recent vertebrate evolution.

genomics↗

bioRxiv2022

Evolutionary conservation of A/T-ending codons reflects co-regulation of expression and complex formation.

BackgroundIn a wide variety of organisms, synonymous codons are used with different frequencies, a phenomenon known as codon bias that plays an important role in determining expression levels. However, the importance of codon bias to facilitate the simultaneous turnover of thousands of protein-coding transcripts to bring about phenotypic changes in cellular programs such as development, has not yet been investigated in detail. ResultsHere, we discover that genes with A/T-ending codon preferences are expressed coordinately and display a high codon conservation in mammals. This feature is not observed in genes enriched in G/C-ending codons. A paradigmatic case of this phenomenon is KRAS, from the RAS family, an A/T-rich gene with a high codon conservation (95%) in comparison to HRAS (76%). Also, we find that genes with similar codon composition are more likely to be part of the same protein complex, and that genes with A/T-ending codons are more prone to form protein complexes than those rich in G/C. The codon preferences of genes with A/T-ending codons are conserved among vertebrates. We propose that codon conservation, a feature of expression-coordinated transcripts, is linked to the high expression variation and coordination of tRNA isoacceptors reading A/T-ending codons. ConclusionsOur data indicate that cells exploit A/T-ending codons to generate coordinated, fine-tuned changes of protein-coding transcripts. We suggest that this orchestration contributes to tissue-specific and ontogenetic-specific expression, which can facilitate, for instance, timely protein complex formation.

evolutionary biology↗

bioRxiv2022

Parallel evolution of amphioxus and vertebrate small-scale gene duplications

BackgroundAmphioxus are non-vertebrate chordates characterized by a slow morphological and molecular evolution. They share the basic chordate body-plan and genome organization with vertebrates but lack their 2R whole-genome duplications and their developmental complexity. For these reasons, amphioxus are frequently used as an outgroup to study vertebrate genome evolution and Evo-Devo. Aside from whole-genome duplications, genes continuously duplicate on a smaller scale. Small-scale duplicated genes can be found in both amphioxus and vertebrate genomes, while only the vertebrate genomes have duplicated genes product of their 2R whole-genome duplications. Here, we explore the history of small-scale gene duplications in the amphioxus lineage and compare it to small- and large-scale gene duplication history in vertebrates. ResultsWe present a study of the European amphioxus (Branchiostoma lanceolatum) gene duplications thanks to a new, high-quality genome reference. We find that, despite its overall slow molecular evolution, the amphioxus lineage has had a history of small-scale duplications similar to the one observed in vertebrates. We find parallel gene duplication profiles between amphioxus and vertebrates, and conserved functional constraints in gene duplication. Moreover, amphioxus gene duplicates show levels of expression and patterns of functional specialization similar to the ones observed in vertebrate duplicated genes. We also find strong conservation of gene synteny between two distant amphioxus species, B. lanceolatum and B. floridae, with two major chromosomal rearrangements. ConclusionsIn contrast to their slower molecular and morphological evolution, amphioxus small-scale gene duplication history resembles that of the vertebrate lineage both in quantitative and in functional terms.

evolutionary biology↗

bioRxiv2021

Specialization of the photoreceptor transcriptome by Srrm3-dependent microexons is required for outer segment maintenance and vision

Retinal photoreceptors differ in their transcriptomic profiles from other neuronal subtypes, likely as a reflection of their unique cellular morphology and function in the detection of light thorough the ciliary outer segment. We discovered a new layer of this molecular specialization by revealing that the vertebrate retina expresses the largest number of tissue-enriched microexons of all tissue types. A subset of these microexons is included exclusively in photoreceptor transcripts, particularly in genes involved in cilia biogenesis and in vesicle-mediated transport. This microexon program is regulated by Srrm3, a paralog of the neural microexon regulator Srrm4. Despite both proteins positively regulate retina microexons in vitro, only Srrm3 is highly expressed in mature photoreceptors and its deletion in zebrafish results in widespread downregulation of microexon inclusion, severe photoreceptor alterations and blindness. These results shed light into photoreceptors transcriptomic specialization and functionality, uncovering new cell type-specific roles for Srrm3 and microexons with implication for retinal diseases.

systems biology↗

bioRxiv2021

ExOrthist: a tool to infer exon orthologies at any evolutionary distance

Several bioinformatic tools have been developed for genome-wide identification of orthologous and paralogous genes among species. However, no existing tool allows the detection of orthologous/paralogous exons. Here, we present ExOrthist, a fully reproducible Nextflow-based software enabling to (i) infer exon homologs and orthogroups, (ii) visualize evolution of exon-intron structures, and (iii) assess conservation of alternative splicing patterns. ExOrthist not only evaluates exon sequence conservation but also considers the surrounding exon-intron context to derive genome-wide multi-species exon homologies at any evolutionary distance. We demonstrate its use in various evolutionary scenarios, from whole genome duplication to convergence of alternative splicing networks.

genomics↗

bioRxiv2020

Alternative splicing landscapes in Arabidopsis thaliana across tissues and stress conditions highlight major functional differences with animals

BackgroundAlternative splicing (AS) is a widespread regulatory mechanism in multicellular organisms. Numerous transcriptomic and single-gene studies in plants have investigated AS in response to specific conditions, especially environmental stress, unveiling substantial amounts of intron retention that modulate gene expression. However, a comprehensive study contrasting stress-response and tissue-specific AS patterns and directly comparing them with those of animal models is still missing. ResultsWe generated a massive resource for A. thaliana (PastDB; pastdb.crg.eu), comprising AS and gene expression quantifications across tissues, development and environmental conditions, including abiotic and biotic stresses. Harmonized analysis of these datasets revealed that A. thaliana shows high levels of AS (similar to fruitflies) and that, compared to animals, disproportionately uses AS for stress responses. We identified core sets of genes regulated specifically by either AS or transcription upon stresses or among tissues, a regulatory specialization that was tightly mirrored by the genomic features of these genes. Unexpectedly, non-intron retention events, including exon skipping, were overrepresented across regulated AS sets in A. thaliana, being also largely involved in modulating gene expression through NMD and uORF inclusion. ConclusionsNon-intron retention events have likely been functionally underrated in plants. AS constitutes a distinct regulatory layer controlling gene expression upon internal and external stimuli whose target genes and master regulators are hardwired at the genomic level to specifically undergo post-transcriptional regulation. Given the higher relevance of AS in the response to different stresses when compared to animals, this molecular hardwiring is likely required for a proper environmental response in A. thaliana.

plant biology↗

bioRxiv2017

Evolutionary rewiring of the human regulatory network by waves of genome expansion

Genome expansion is believed to be an important driver of the evolution of gene regulation. To investigate the role of newly arising sequence in rewiring the regulatory network we estimated the age of each region of the human genome by applying maximum parsimony to genome-wide alignments with 100 vertebrates. We then studied the age distribution of several types of functional regions, with a focus on regulatory elements. The age distribution of regulatory elements reveals the extensive use of newly formed genomic sequence in the evolution of regulatory interactions. Many transcription factors have expanded their repertoire of targets through waves of genomic expansions that can be traced to specific evolutionary times. Repeated elements contributed a major part of such expansion: many classes of such elements are enriched in binding sites of one or a few specific transcription factors, whose binding sites are localized in specific portions of the element and characterized by distinctive motif words. These features suggest that the binding sites were available as soon as the new sequence entered the genome, rather than being created later by accumulation of point mutations. By comparing the age of regulatory regions to the evolutionary shift in expression of nearby genes we show that rewiring through genome expansion played an important role in shaping the human regulatory network.

evolutionary biology↗