Biology subjects

Escudeiro, P.

Publications and source records attributed to Escudeiro, P..

4 recordsLinked to original sources

bioRxiv2025

Latent endogenous viral elements drive active infection and inheritance in a multicellular host

Endogenous viral elements (EVEs) inserted in host genomes are often regarded as inert relics of past infections. Whether they can retain infective potential and contribute to active viral cycles has remained unresolved. Here, we demonstrate that EVEs in the brown alga Ectocarpus can reactivate and drive productive viral infections. Using long-read sequencing and transcriptomics, we identify full-length, transcriptionally active giant viruses integrated within the host genome. Reactivation of these elements is specific to reproductive cells, transforming gametangia into virus-producing structures, and viral symptoms strictly correlate to the presence of active EVEs. Genetic analyses show that these elements are stably inherited, while their activation is precisely regulated by developmental and environmental cues. By resolving the genomic integration sites, we propose a mechanism for Phaeovirus integration and replication. This work provides the first direct evidence that giant EVEs can reactivate, replicate, and transmit both horizontally and vertically in a multicellular eukaryote, establishing a new model to explore latency, inheritance and the evolutionary impact of large dsDNA viruses.

genetics↗

bioRxiv2024

Tissue-Like Multicellular Development Triggered by Mechanical Compression in Archaea

The advent of clonal multicellularity is a critical evolutionary milestone, seen often in eukaryotes, rarely in bacteria, and only once observed in archaea. We show that uniaxial compression induces clonal multicellularity in haloarchaea, forming tissue-like structures. These archaeal tissues are mechanically and molecularly distinct from their unicellular lifestyle, mimicking several eukaryotic features. Archaeal tissues undergo a multinucleate stage followed by tubulin-independent cellularization, orchestrated by active membrane tension at a critical cell size. After cellularization, tissue junction elasticity become akin to animal tissues and give rise to two cell types--radial peribasal and central apicobasal cells-- with distinct actin and protein glycosylation polarity patterns. Our findings highlight the potential convergent evolution of a biophysical mechanism in the emergence of multicellular systems across domains of life.

cell biology↗

bioRxiv2024

Halofilins as Emerging Bactofilin Families of Archaeal Cell Shape Plasticity Orchestrators

Bactofilins are rigid, non-polar bacterial cytoskeletal filaments that link cellular processes to specific curvatures of the cytoplasmic membrane. Although homologs of bactofilins have been identified in archaea and eukaryotes, functional studies have remained confined to bacterial systems. Here, we characterize representatives of two new families of archaeal bactofilins from the pleomorphic archaeon Haloferax volcanii, halofilin A (HalA) and halofilin B (HalB). HalA and HalB polymerize in vitro, assembling into straight bundles. HalA polymers are highly dynamic and accumulate at positive membrane curvatures in vivo, whereas HalB forms more static foci that localize in areas of local negative curvatures on the outer cell surface. Gene deletions and live-cell imaging show that halofilins are critical in maintaining morphological integrity during shape transition from disk (sessile) to rod (motile). Morphological defects in {Delta}halA result in accumulation of highly positive curvatures in rods but not in disks. Conversely, disk-shaped cells are exclusively affected by halB deletion, resulting in flatter cells. Furthermore, while {Delta}halA and {Delta}halB cells imprecisely determine the future division plane, defects arise predominantly during the disk-to-rod shape remodeling. In fact, the deletion of halA in the haloarchaeon Halobacterium salinarum, whose cells are consistently rod-shaped, impacted morphogenesis but not cell division. Increased levels of halofilins enforced drastic deformations in cells devoid of S-layer, suggesting that HalB polymers are more stable at defective S-layer lattice regions. Our results set halofilins apart from their bacterial correlate, where they provide mechanical scaffolding instead of directing envelope synthesis.

microbiology↗

bioRxiv2018

Correlation among antibiotic resistance and virulence traits in human gut microbiomes

Human beings have used large amounts of antibiotics, not only in medical contexts but also, for example, as growth factors in agriculture and livestock, resulting in the contamination of the environment. Even when pathogenic bacteria are the targets of antibiotics, hundreds of non-pathogenic bacterial species are affected as well. Therefore, both pathogenic and non-pathogenic bacteria have gradually become resistant to antibiotics. We tested whether there is still co-occurrence of resistance and virulence determinants. We performed a comparative study of environmental and human gut metagenomes issuing from different individuals and from distinct human populations across the world. We found a great diversity of antibiotic resistance determinants (ARd) and virulence factors (VFd) in metagenomes. Importantly there is a correlation between ARd and VFd, even after correcting for protein family richness. In the human gut there are less ARd and VFd than in more diversified environments, and yet correlations between the ARd and VFd are stronger. They can vary from very high in Malawi, where antibiotic consumption is unattended, to non-existent in the uncontacted Amerindians. We conclude that there is co-occurrence of resistance and virulence determinants, suggesting a possible co-selective mechanism. For example, by selecting for resistant bacteria, we may be selecting for more virulent strains as a side effect of antimicrobial therapy.

genomics↗