Biology subjects

Andrade, S.

Publications and source records attributed to Andrade, S..

3 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↗

bioRxiv2023

Reconstructing stochastic cell population trajectories reveals regulators and heterogeneity of endothelial flow-migration coupling driving vascular remodelling

Emerging concepts of developmental vascular remodelling recently identified that selectively labelled sprouting tip cells and/or venous endothelial cells (ECs) accumulate in developing arteries, suggesting directional migration of specific ECs drives artery formation. However, a general population analysis and detailed quantitative investigation of migratory mechanisms is so far lacking. Here, we developed a universally applicable quantitative approach and a computational model allowing to track and simulate stochastically labelled EC populations irrespective of labelling density and origin. Dynamic mapping of EC distributions in a bespoke coordinate system revealed how ECs move during the most active remodelling phases in the mouse retina. Simulation and parameter sensitivity analysis illustrated that the population shift from veins to arteries cannot be explained by random walk, but best fits to a tuneable dual force-field between shear-force induced directionality against blood flow, and hypoxia mediated VEGFA-gradients. High migration rates require only weak flow-migration coupling, whereas low migration rates require strong coupling to the flow direction. Functional analysis identified Cdc42 as the critical mediator of overall population movement from veins to arteries, yet with surprising heterogeneity suggesting the existence of distinct cell populations. This new quantitative understanding will enable future tailored intervention and tuning of the remodelling process.

developmental biology↗

bioRxiv2021

Spatial and temporal assessment of the risk associated to bacteria in recreational waters of a large South American Reservoir

The characterization of risk due to recreational exposure to water needs to assess the concentration of pathogens in the water and the degree of contact with those pathogens. In this study we assessed the risk associated to E. coli and cyanobacteria in a large South American Reservoir heavily used for recreation, by i) gathering field environmental data from two water agencies (six sites, summers 2011-2015), ii) generating satellite data at landscape scale (750 km2, summers 2011-2017) and running a health survey related to water exposure (summer 2017). Field data showed that cyanobacteria abundances recurrently surpassed the moderate and high-risk categories across sites and year analyzed, and a significant positive link between cyanobacteria abundance and microcystin concentration. Nevertheless, microcystin concentrations were in 90% of cases mostly within the low to moderate risk categories. Mean E. coli concentrations during 2011-2015 were within the high-risk category in 30% of the sites, but in 2017, sites identified as low risk had high-risk. The latter underscores the high risk posed by E. coli in the reservoir. Cyanobacteria (cell abundance and microcystin) and coliform bacteria abundances were unrelated, suggesting different responses to environmental or anthropogenic triggers. Satellite data evidenced that the highest risk related to cyanobacteria abundance occurred in the dendritic areas of the Argentinean side of the reservoir, areas which currently remain unmonitored by water agencies. Satellite monitoring bridged the limited spatial and temporal coverage of field samplings for cyanobacteria abundance (yet not for toxicity nor E. coli abundances) and rendered a risk map at landscape scale, which can be used by water agencies to effectively monitor and manage cyanobacteria blooms, and to-coupled with exposure variables-assess health risks related to cyanobacteria. The health survey identified few numbers of suspected patients with symptoms and who bathed in the Salto Grande reservoir. At the time of exposure, sites in the environment evidenced high bacteria concentration (mostly E. coli and to a lesser extent cyanobacteria) denoting situations where aspects of the biophysical environment affect human health. More studies and integration among environmental and health disciplines are needed to assess the impacts of these water born bacteria in human health. Finally, we further assessed how well cyanobacteria quantitative proxies monitored in the field explained the outcome of a qualitative risk communication system-the cyano-traffic-light-which is ongoing since 2011. We obtained a significant predictive model only for cyanobacteria abundance, yet with low predictive value. This probably occurred because the variables used to build each cyano-traffic-light category (cyanobacteria abundance, toxicity and chlorophyll-a, scums) were monitored with different frequencies, and because at least two of these variables needed to surpass the threshold of each category to be allocated into a risk category. Based upon our results we propose several modifications to the current cyano-traffic-light, that believe would better reflect what happens in the field and protect human health: i) include E. coli concentration and satellite estimated cyanobacteria abundance (mostly in areas not covered by field monitoring), ii) relax the thresholds for cyanobacteria abundance and toxicity, and iv) base each risk category upon the surpassing of one of either E. coli, cyanobacteria abundance, microcystin.

ecology↗