Biology subjects

Barria, C.

Publications and source records attributed to Barria, C..

4 recordsLinked to original sources

bioRxiv2025

Predicting Potential Spawning Areas: a novel framework for elasmobranch conservation and spatial management

Defining and protecting critical habitats for elasmobranchs (sharks and rays), such as spawning areas, is essential for mitigating anthropogenic pressures that threaten their populations, primarily driven by fisheries and habitat degradation. This study presents a novel modelling-based framework to identify Potential Spawning Areas (PSAs) - habitats offering optimal conditions for oviposition. Using fisheries-dependent trawl bycatch data combined with environmental and anthropogenic predictors, we applied machine-learning models to delineate PSAs for the smallspotted catshark (Scyliorhinus canicula) and skates (Raja spp.) in the western Mediterranean. Static environmental predictors, including depth and slope, were primary drivers, while dynamic predictors, including sea bottom temperature and salinity played seasonally relevant roles. Trawl fishing pressure also influenced importantly the distribution of PSAs, revealing a concerning positive feedback loop between exploitation and habitat degradation. While PSAs experienced lower fishing effort than the rest of the study area, a substantial proportion of egg case bycatch still occurs within them. The current network of Marine Protected Areas in the region fails to adequately safeguard these habitats due to limited coverage and enforcement. Our findings underscore significant gaps in spatial management and the urgent need for targeted conservation measures. The PSA framework provides a robust, scalable tool for identifying critical habitats across regions and species, offering actionable insights for marine spatial planning and ecosystem-based management. This adaptable approach can support global conservation efforts for elasmobranchs and their ecosystems. SignificanceSharks and rays are vital to marine ecosystems but face alarming extinction risks due to overfishing and habitat loss. Identifying critical reproductive habitats, such as spawning areas, is essential for protection but remains a significant challenge. This study introduces a novel framework for identifying Potential Spawning Areas (PSAs) - habitats offering optimal conditions for oviposition - using machine-learning and fisheries bycatch data. Applied in the western Mediterranean for the smallspotted catshark and skates, it demonstrates how environmental factors and fishing pressures shape these habitats, highlighting significant management gaps. The PSAs framework offers a scalable approach to guide the establishment of marine protected areas and fisheries management plans, providing a novel approach for conserving vulnerable marine species and their habitats.

ecology↗

bioRxiv2023

RNase R Controls Membrane Fatty Acid Composition in Streptococcus pneumoniae

AO_SCPLOWBSTRACTC_SCPLOWPrevious studies on RNase R have highlighted significant effects of this ribonuclease in several processes of Streptococcus pneumoniae biology. In this work we have studied the global impact of RNase R by comparing the transcriptional landscape of a deleted RNase R mutant to that of the wild-type strain, and this led us investigate specific targets affected by RNase R. RNA-Seq showed that RNase R deletion affects transcripts from several different biological processes. Of particular interest, elimination of RNase R results in overexpression of most of the genes encoding the components of type II fatty acid biosynthesis (FAS-II) cluster. We demonstrate that RNase R governs the turnover of most of genes from this pathway, affecting the outcome of the whole FAS-II cluster, and leading to an unbalanced membrane fatty acid composition. Our results show that the membrane of the deleted strain contains a higher proportion of unsaturated and long-chained fatty acids than the wild type strain. This leads to a higher fluidity of the {Delta}rnr mutant membrane, which is probably related with the increased sensitivity to detergent observed in this strain. We demonstrate that RNase R expression is induced in cells challenged with H2O2, which is suggestive of a role for this ribonuclease on the regulation of membrane homeostasis under oxidative stress. Reprogramming of membrane fluidity is an adaptative cell response crucial for bacterial survival in constantly changing environmental conditions. The fact that RNase R controls the expression of several essential genes to the fatty acid synthesis unveils a new important function of this enzyme.

molecular biology↗

bioRxiv2021

RNase R, a new virulence determinant of Streptococcus pneumoniae

Pneumococcal infections have increasingly high mortality rates despite the availability of vaccines and antibiotics. The increase of bacterial resistance to antibiotics urges the discovery of new alternative therapeutics. Therefore, the identification of new virulence determinants, and the understanding of the molecular mechanisms behind pathogenesis and pneumococcal-host interactions has become of paramount importance in the search of new targets for drug development. The exoribonuclease RNase R has been involved in virulence in a growing number of pathogens. In this work, we have used Galleria mellonella as an infection model to demonstrate that the presence of ribonuclease R increases the pneumococcus virulence. Although the absence of RNase R does not affect exponential growth, the ability of the RNase R deleted strain to replicate in the hemolymph is compromised. Larvae infected with the RNase R mutant strain show an increased expression level of antimicrobial peptides, and have a lower bacterial load in the haemolymph in the later stages of infection, leading to a higher survival rate. Interestingly RNase R carrying pneumococci suffer a sudden drop in bacterial numbers immediately after infection, resembling the eclipse phase observed after intravenous inoculation in mice. Together our results suggest that RNase R might be involved in the ability of pneumococci to evade the host immune response, probably by interfering with internalisation and/or replication inside the larval hemocytes.

molecular biology↗

bioRxiv2021

New targets for drug design: Importance of nsp14/nsp10 complex formation for the 3'-5' exoribonucleolytic activity on SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has triggered a global pandemic with devastating consequences for health-care and social-economic systems. Thus, the understanding of fundamental aspects of SARS-CoV-2 is of extreme importance. In this work, we have focused our attention on the viral ribonuclease (RNase) nsp14, since this protein was considered one of the most interferon antagonists from SARS-CoV-2, and affects viral replication. This RNase is a multifunctional protein that harbors two distinct activities, an N-terminal 3-to-5 exoribonuclease (ExoN) and a C-terminal N7-methyltransferase (N7-MTase), both with critical roles in coronaviruses life cycle. Namely, SARS-CoV-2 nsp14 ExoN knockout mutants are non-viable, indicating nsp14 as a prominent target for the development of antiviral drugs. Nsp14 ExoN activity is stimulated through the interaction with the nsp10 protein, which has a pleiotropic function during viral replication. In this study, we have performed the first biochemical characterization of the complex nsp14-nsp10 from SARS-CoV-2. Here we confirm the 3-5 exoribonuclease and MTase activities of nsp14 in this new Coronavirus, and the critical role of nsp10 in upregulating the nsp14 ExoN activity in vitro. Furthermore, we demonstrate that SARS-CoV-2 nsp14 N7-MTase activity is functionally independent of the ExoN activity. The nsp14 MTase activity also seems to be independent of the presence of nsp10 cofactor, contrarily to nsp14 ExoN. Until now, there is no available structure for the SARS-CoV-2 nsp14-nsp10 complex. As such, we have modelled the SARS-CoV-2 nsp14-nsp10 complex based on the 3D structure of the complex from SARS-CoV (PDB ID 5C8S). We also have managed to map key nsp10 residues involved in its interaction with nsp14, all of which are also shown to be essential for stimulation of the nsp14 ExoN activity. This reinforces the idea that a stable interaction between nsp10 and nsp14 is strictly required for the nsp14-mediated ExoN activity of SARS-CoV-2, as observed for SARS-CoV. We have studied the role of conserved DEDD catalytic residues of SARS-CoV-2 nsp14 ExoN. Our results show that motif I of ExoN domain is essential for the nsp14 function contrasting to the functionality of these conserved catalytic residues in SARS-CoV, and in the Middle East respiratory syndrome coronavirus (MERS). The differences here revealed can have important implications regarding the specific pathogenesis of SARS-CoV-2. The nsp10-nsp14 interface is a recognized attractive target for antivirals against SARS-CoV-2 and other coronaviruses. This work has unravelled a basis for discovering inhibitors targeting the specific amino acids here reported, in order to disrupt the assembly of this complex and interfere with coronaviruses replication.

microbiology↗