12 research outputs found
Structure/Function Analysis of a Type III Polyketide Synthase in the Brown Alga Ectocarpus siliculosus
Extraction and Purification of Phlorotannins from Brown Algae
International audienceThe interest in the physiological roles and bioactivities of plant phenols has increased over the past decades. In seaweeds, many investigations have dealt with phenolic compounds of Phaeophyceae (phlorotannins), even though little is known so far about the ecophysiological variations of their pool or their biosynthetic pathways. We describe here a simple procedure based on the use of water-organic solvent mixtures for the extraction of phlorotannins. Crude extracts are semi-purified and fractionated by separating methods based on both the polarity and the molecular size of compounds. Phenols are then quantified by the Folin-Ciocalteu method and their radical-scavenging activity is characterized using the DPPH test. All along the purification process of phenolic compounds, the efficiency of separation is assessed by 1H-NMR
Comparison of supervised classifications to discriminate seaweed-dominated habitats through hyperspectral imaging data
International audienceIntertidal macroalgae define complex habitats and play a key role in structuring coastal areas. While, they are primarily studied during field campaigns, remote sensing acquisitions are becoming increasingly prevalent. However, the use of hyperspectral imagery on drones is not developed even though it allows species identification even in heterogeneous environments such as intertidal rocky shores. Based on hyperspectral drone imagery acquired in summer 2021, this study aims to identify and validate an algorithm suitable for easy integration into an operational framework for monitoring macroalgal dominated shore. The study focuses on two sites along the Brittany coast (Western France). Species identification and abundance were determined in the field. Six algorithms were tested: Mahalanobis, Minimum Distance, Maximum Likelihood, Random Forest, Spectral Angle Mapper and Support Vector Machine. Classifications showed overall accuracies ranging from 70% to 90% depending on the algorithm. The Maximum Likelihood is retained as it provides good accuracies and valuable information about the species distributions. Our analyses based on a combination of field and remote sensing data reveals globally consistent results when considering the main Phaeophyceae species but a divergence was highlighted for Rhodophyta. Despite environmental differences, the two studied sites were faithfully characterized in terms of intertidal species and habitat distribution, highlighting the potential of hyperspectral drone imagery to better understand seaweed-dominated ecosystem dynamics
Structure/Function analysis of a type iii polyketide synthase in the brown alga Ectocarpus siliculosus reveals a biochemical pathway in phlorotannin monomer biosynthesis.
International audienceBrown algal phlorotannins are structural analogs of condensed tannins in terrestrial plants and, like plant phenols, they have numerous biological functions. Despite their importance in brown algae, phlorotannin biosynthetic pathways have been poorly characterized at the molecular level. We found that a predicted type III polyketide synthase in the genome of the brown alga Ectocarpus siliculosus, PKS1, catalyzes a major step in the biosynthetic pathway of phlorotannins (i.e., the synthesis of phloroglucinol monomers from malonyl-CoA). The crystal structure of PKS1 at 2.85-Ă
resolution provided a good quality electron density map showing a modified Cys residue, likely connected to a long chain acyl group. An additional pocket not found in other known type III PKSs contains a reaction product that might correspond to a phloroglucinol precursor. In vivo, we also found a positive correlation between the phloroglucinol content and the PKS III gene expression level in cells of a strain of Ectocarpus adapted to freshwater during its reacclimation to seawater. The evolution of the type III PKS gene family in Stramenopiles suggests a lateral gene transfer event from an actinobacterium
Suivi citoyen des indicateurs des alĂ©as dâĂ©rosion cĂŽtiĂšre et de submersion marine : crĂ©ation de lâapplication smartphone et tablette CoastAppli et expĂ©rimentation Ă GuissĂ©ny (FinistĂšre)
International audienceLes alĂ©as cĂŽtiers (Ă©rosion, submersion, migration dunaire) et les dynamiques cĂŽtiĂšres sont souvent mĂ©connus par le grand public. Or, dans un contexte de changement climatique et dâĂ©volution de la lĂ©gislation (loi « Climat et rĂ©silience » en 2021) sur la gestion des alĂ©as et des risques cĂŽtiers (risque(s) combinant alĂ©a(s) et enjeu(x)), le suivi de lâĂ©volution du littoral au travers dâindicateurs des alĂ©as cĂŽtiers (position du trait de cĂŽte, niveau de la plage, niveau dâeau sur un repĂšre lors dâune submersion, etc.) devrait ĂȘtre lâaffaire de tous. JusquâĂ prĂ©sent, aucune application citoyenne pour smartphone ou tablette ne permettait de suivre conjointement les indicateurs des alĂ©as cĂŽtiers dâĂ©rosion et de submersion, alors que ces deux alĂ©as sont souvent liĂ©s. Pour y remĂ©dier, dans le cadre dâun projet de recherche et de formation (2019-2022) regroupant des Ă©tudiants en gĂ©ographie, en biologie et en informatique, nous avons crĂ©Ă© lâapplication Android CoastAppli. CoastAppli, qui vise un public large (habitants, touristes, scolaires, gestionnaires du littoral, etc.) et a Ă©tĂ© expĂ©rimentĂ©e Ă GuissĂ©ny (FinistĂšre) entre janvier et octobre 2022 auprĂšs de 86 personnes, permet de rĂ©aliser un suivi citoyen des indicateurs dâalĂ©as cĂŽtiers. GrĂące Ă lâimplication des utilisateurs sur les quatre sites de cette commune, les rĂ©sultats soulignent la fiabilitĂ© des donnĂ©es quantitatives (jusquâĂ une erreur globale de ± 4 cm) et/ou qualitatives, ainsi que la haute frĂ©quence dâacquisition (mensuelle). Par ailleurs, cela semble un bon moyen pour comprendre, discuter et rĂ©flĂ©chir entre acteurs du territoire aux dĂ©fis de gestion du littoral dâaujourdâhui et de demain
Suivi citoyen des indicateurs des alĂ©as dâĂ©rosion cĂŽtiĂšre et de submersion marine : crĂ©ation de lâapplication smartphone et tablette CoastAppli et expĂ©rimentation Ă GuissĂ©ny (FinistĂšre)
International audienceLes alĂ©as cĂŽtiers (Ă©rosion, submersion, migration dunaire) et les dynamiques cĂŽtiĂšres sont souvent mĂ©connus par le grand public. Or, dans un contexte de changement climatique et dâĂ©volution de la lĂ©gislation (loi « Climat et rĂ©silience » en 2021) sur la gestion des alĂ©as et des risques cĂŽtiers (risque(s) combinant alĂ©a(s) et enjeu(x)), le suivi de lâĂ©volution du littoral au travers dâindicateurs des alĂ©as cĂŽtiers (position du trait de cĂŽte, niveau de la plage, niveau dâeau sur un repĂšre lors dâune submersion, etc.) devrait ĂȘtre lâaffaire de tous. JusquâĂ prĂ©sent, aucune application citoyenne pour smartphone ou tablette ne permettait de suivre conjointement les indicateurs des alĂ©as cĂŽtiers dâĂ©rosion et de submersion, alors que ces deux alĂ©as sont souvent liĂ©s. Pour y remĂ©dier, dans le cadre dâun projet de recherche et de formation (2019-2022) regroupant des Ă©tudiants en gĂ©ographie, en biologie et en informatique, nous avons crĂ©Ă© lâapplication Android CoastAppli. CoastAppli, qui vise un public large (habitants, touristes, scolaires, gestionnaires du littoral, etc.) et a Ă©tĂ© expĂ©rimentĂ©e Ă GuissĂ©ny (FinistĂšre) entre janvier et octobre 2022 auprĂšs de 86 personnes, permet de rĂ©aliser un suivi citoyen des indicateurs dâalĂ©as cĂŽtiers. GrĂące Ă lâimplication des utilisateurs sur les quatre sites de cette commune, les rĂ©sultats soulignent la fiabilitĂ© des donnĂ©es quantitatives (jusquâĂ une erreur globale de ± 4 cm) et/ou qualitatives, ainsi que la haute frĂ©quence dâacquisition (mensuelle). Par ailleurs, cela semble un bon moyen pour comprendre, discuter et rĂ©flĂ©chir entre acteurs du territoire aux dĂ©fis de gestion du littoral dâaujourdâhui et de demain
Can CoastAppli (a citizen science smartphone app) improve monitoring and understanding of coastal hazards to support coastal management?
International audienceCoastal erosion and flooding remain unknown hazards and elected officials and coastal managers may have difficulty discussing these phenomena with the general public. However, a better knowledge of the evolution of these hazards, through citizen science, can help raise awareness of coastal dynamics among the general public and thus meet the current and future challenges of coastal management. During the OSIRISC project (2016-2020), funded by the Fondation de France, coastal managers wanted to set up a smartphone app to save time during their field surveys, while allowing citizens to perform some measurements. How to create a citizen science app on coastal hazards that is reliable and intelligible and that guarantees the sustainable support of participants (professionals and non professionals)? Within the framework of the observatory of coastal risks in Brittany (OSIRISC), protocols for measuring hazards 1) with common tools (benchmarks such as the size of one's finger, qualitative data with photographs) or cheap tools (tape measure, laser distance meter...), 2) applicable to all types of coasts (beach, cliffâŠ) have been co-designed with the managers and integrated into the android app called CoastAppli. Co-funded by EUR ISblue (the interdisciplinary graduate school for the blue planet), Sea-Eu and Interreg AGEO projects, CoastAppli is currently being tested for 6 months (until April 2022) in the municipality of GuissĂ©ny (Brittany, France) by grade school students, coastal managers and citizens. The feedback from this test will allow us to know: i) the reliability of the measurements; ii) whether the app meets the expectations of the coastal managers by saving time for data collection in the field; iii) the app ability to be understood and educative; iv) the sustainability of the commitment of the citizens. These results are essential to validate the application before a future deployment that is intended in Brittany, then in France and beyond