Biology subjects

Rato, C.

Publications and source records attributed to Rato, C..

6 recordsLinked to original sources

bioRxiv2026

Pathogen-dependent biocontrol activity of Chlorella sorokoniana aqueous extracts against fungal and oomycete plant pathogens

Fungal and oomycete plant pathogens are major drivers of yield losses worldwide and are spurring the search for sustainable alternatives to synthetic pesticides. Algae, in general, and microalgae, in particular, represent a promising source of bioactive compounds for crop protection. Despite this, their efficacy across different host-pathogen systems remains poorly characterised. This study evaluated the biocontrol potential of the aqueous extract of Chlorella sorokoniana against three economically important phytopathogens using complementary in vitro, ex vivo, and in planta assays. The strongest activity was observed against Magnaporthe oryzae, with the extract reducing fungal growth by approximately 70% in vitro, inhibiting appressorium formation by 55%, suppressing lesion development on detached rice leaves by more than 75%, and reducing rice blast severity by 64.5% as a preventive foliar treatment. In contrast, the extract showed little or no direct in vitro antifungal activity against Pythium ultimum and Rhizoctonia solani, yet it significantly reduced disease severity in planta by 13-37% and 48-55%, respectively. The contrasting responses among pathosystems suggest that C. sorokoniana aqueous extracts act through different mechanisms depending on the pathogen and the crop, combining direct antifungal activity against M. oryzae with plant-associated protective effects against soil-borne pathogens. These findings highlight the importance of evaluating candidate biocontrol products using complementary in vitro and in planta approaches, as laboratory antimicrobial assays alone may substantially underestimate their agricultural potential. The broad-spectrum protection achieved with an unrefined aqueous extract further supports C. sorokoniana as a promising source of sustainable crop protection products and provides a strong foundation for future mechanistic studies, formulation development, and field validation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/742703v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@428ebaorg.highwire.dtl.DTLVardef@1a85992org.highwire.dtl.DTLVardef@190a605org.highwire.dtl.DTLVardef@183b905_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2025

From ashes to adaptation: the impact of wildfires on the diet of Podarcis lusitanicus revealed by DNA metabarcoding

Fire has long been recognized as an important ecological and evolutionary force in plant communities, but its influence on animals, particularly regarding predator-prey interactions, remains understudied. This study focuses on the impact of wildfires on the diet of Podarcis lusitanicus, a lizard species inhabiting a fire-prone region in the Iberian Peninsula. Faecal samples were collected from 12 distinct locations in Northern Portugal, at sites that burned in two distinct years (2016 and 2022), and in sites unburned since at least 2016. Podarcis lusitanicus is a generalist arthropod predator with dietary flexibility. Given the turnover of arthropod species after fire, it is expected to find variations in diet caused by different fire histories, especially between unburnt and recently burnt sites. Using DNA metabarcoding approach, employing high-throughput sequencing, the study revealed that while prey richness remained unaffected by wildfire regime, significant shifts occurred in diet composition between more recently burned and unburned areas, demonstrating a likely influence on prey availability after a more recent fire. Specifically, we found that differences in diet composition between these two fire regimes were due to the presence of Tapinoma ants and jumping spiders (Salticus scenicus) in unburned areas, while these were absent in areas burned in 2022. Interestingly, diets in unburned areas and areas burned in 2016 showed no significant differences, highlighting the lizards adaptability and the habitats resilience over time. Talitroides topitotum was found in dominance in both burnt areas, suggesting that this species may be fire tolerant. In addition, families such as Cicadellidae and Noctuidae were found to be more associated with more recently burned areas. The use of DNA metabarcoding in this study was essential to provide a more detailed and accurate view of predator-prey interactions in ecosystems susceptible to fire, providing a better understanding of changes in prey consumption in these environments.

ecology↗

bioRxiv2021

Uncovered genetic diversity in Hemidactylus mabouia (Reptilia: Gekkonidae) from Madeira Island reveals uncertain sources of introduction

Hemidactylus mabouia is one of the most widely distributed species within its genus. It was first reported to Madeira in 2002 and the first individuals were considered to have originated from Cape Verde. Almost 20 years later, we found that H. mabouia has substantially expanded its distribution and can now be found >10 km away from Funchal, where it was first reported. Based on a 12S phylogenetic analysis and using 29 individuals from Funchal and Camara de Lobos we found that Madeira actually harbours two distinct lineages of H. mabouia: one exclusively South American and another widespread in America and Africa. However, the lack of genetic diversity typical of this species outside its native range and the obtained phylogenetic pattern prevent us to infer possible introduction routes or sources. Our study emphasizes that authorities should remain vigilant regarding the arrival of other non-natives and act to prevent their establishment as soon as they are detected.

evolutionary biology↗

bioRxiv2020

Calcium depletion challenges endoplasmic reticulum proteostasis by destabilising BiP-substrate complexes

The metazoan endoplasmic reticulum (ER) serves both as a hub for maturation of secreted proteins and as an intracellular calcium storage compartment, facilitating calcium release-dependent cellular processes. ER calcium depletion robustly activates the unfolded protein response (UPR). However, it is unclear how fluctuations in ER calcium impact organellar proteostasis. Here we report that calcium selectively affects the dynamics of the abundant metazoan ER Hsp70 chaperone BiP, by enhancing its affinity for ADP. In the calcium replete ER, ADP rebinding to post-ATP hydrolysis BiP-substrate complexes competes with ATP binding during both spontaneous and co-chaperone-assisted nucleotide exchange, favouring substrate retention. Conversely, in the calcium depleted ER, relative acceleration of ADP-to-ATP exchange favours substrate release. These findings explain the rapid dissociation of certain substrates from BiP observed in the calcium-depleted ER and suggest a mechanism for tuning ER quality control and coupling UPR activity to signals that mobilise ER calcium in secretory cells.

biochemistry↗

bioRxiv2020

ISRIB blunts the integrated stress response by allosterically antagonising the inhibitory effect of phosphorylated eIF2 on eIF2B

The small molecule ISRIB antagonises the activation of the integrated stress response (ISR) by phosphorylated translation initiation factor 2, eIF2(P). ISRIB and eIF2(P) bind distinct sites in their common target, eIF2B, a guanine nucleotide exchange factor (GEF) for eIF2. We have found that ISRIB-mediated acceleration of eIF2B activity in vitro is observed preferentially in the presence of eIF2(P) and is attenuated by mutations that desensitise eIF2B to the inhibitory effects of eIF2(P). ISRIBs efficacy as an ISR inhibitor in cells also depends on presence of eIF2(P). Cryo-EM showed that engagement of both eIF2B regulatory sites by two eIF2(P) molecules remodels both the ISRIB-binding pocket and the pockets that would engage eIF2 during active nucleotide exchange, thereby discouraging both binding events. In vitro, eIF2(P) and ISRIB reciprocally opposed each others binding to eIF2B. These findings point to antagonistic allostery in ISRIB action on eIF2B, culminating in inhibition of the ISR.

biochemistry↗

bioRxiv2019

An oligomeric state-dependent switch in FICD regulates AMPylation and deAMPylation of the chaperone BiP

AMPylation is an inactivating modification that matches the activity of the major endoplasmic reticulum (ER) chaperone BiP to the burden of unfolded proteins. A single ER-localised Fic protein, FICD (HYPE), catalyses both AMPylation and deAMPylation of BiP. However, the basis for the switch in FICDs activity is unknown. We report on the transition of FICD from a dimeric enzyme, that deAMPylates BiP, to a monomer with potent AMPylation activity. Mutations in the dimer interface or in residues tracing an inhibitory relay from the dimer interface to the enzymes active site favour BiP AMPylation in vitro and in cells. Mechanistically, monomerisation relieves a repressive effect allosterically-propagated from the dimer interface to the inhibitory Glu234, thereby permitting AMPylation-competent binding of MgATP. Whereas, a reciprocal signal propagated from the nucleotide binding site, provides a mechanism for coupling the oligomeric-state and enzymatic activity of FICD to the energy status of the ER.\n\nImpact StatementUnique amongst known chaperones, the endoplasmic reticulum (ER)-localized Hsp70, BiP, is subject to transient inactivation under conditions of low ER stress by reversible, covalent modification - AMPylation. The enzyme responsible for this modification, FICD, is in fact a bifunctional enzyme with a single active site capable of both AMPylation and deAMPylation. Here we elucidate, by biochemical, biophysical and structural means, the mechanism by which this enzyme is able to switch enzymatic modality: by regulation of its oligomeric state. The oligomeric state-dependent reciprocal regulation of FICD activity is, in turn, sensitive to the ATP/ADP ratio. This allosteric pathway potentially facilitates the sensing of unfolded protein load in the ER and permits the transduction of this signal into a post-translational buffering of ER chaperone activity.

biochemistry↗