Since 2011, a few highlights have punctuated the years at CEBA. The first part of the year offers the opportunity to finance new scientific projects. After the 2020 call between science and the citizen, the new 2021 call for projects was definitely targeted “100% science”.
After few weeks of evaluation, the direction committee and scientific board made their choices. While waiting for the launch of these new projects, here is a preview of what we will be talking about in 2021.
Combining chemical and genomics levels to decipher acetogenins production in Annona species
David TOUBOUL, ICNS
The tropical family Annonaceae is one of the best studied tropical plant families (mainly trees; 110 genera and about 2,430 species). The tropical family Annonaceae has economic importance in the food-processing industry and fresh fruit local markets, mainly with members of the genus Annona. These plants are also widely used in traditional medicine. Case-control studies suggested consumption of the fruits of Annonaceae and herbal infusions derived from these plants as the cause of the high prevalence of sporadic atypical Parkinsonism/dementia clusters reported in Guadeloupe, Martinique, New Caledonia and French Guiana. Phytochemical and toxicological studies have identified Annonaceous acetogenins (AAGs), a class of polyketides specific to the Annonaceae, as candidate neurotoxins. The French and European Food Safety Agencies expressed its concern about this issue. The ANNONA project aims to combine chemistry and genomics approaches to answer questions related to Annonaceae present and regularly consumed in Guyana.
Drought resilience in seasonally flooded forests
Marion Boisseaux, ECOFOG
An important unanswered question in the understanding of plant strategies is the extent to which the microbial community contributes to tropical forest functioning. In roots, the beneficial effects of the microbiome, mycorrhizal fungi or Nitrogen-fixing bacteria, are known to promote nutrient and water uptake, stimulate germination, growth and plant fitness under abiotic stress. The challenge is now to analyze how tree-microbiome interactions will affect the resistance and the resilience of plants in a changing environment. Indeed, more frequent and intense drought events are being forecasted over the Amazon Basin. This project is carried out within the framework of the PhD thesis of M. Boisseaux on the relationships between species’ mechanistic traits and their distribution across contrasted habitats in the tropical forests of French Guiana in a context of climate change. It will provide significant insight into the strategies of tropical species to cope with drought and improve our predictions of ecosystem functioning under future climatic regimes.
Successional patterns of endophytic bacteria and fungi over plant ontogeny.
Tristan Lafont Rapnouil, AMAP
Ecologists have documented the process of plant succession for centuries, yet the successional patterns exhibited by the associated microbial communities have received relatively little attention. Plants form microhabitats for a large diversity of microbiota that offer significant benefits to their host plants. By its nature, this inherited microbiota might be selected and transmitted over generations and provide valuable and lasting benefits to its host plant. However, little is known about the contribution of seed-borne endophytes over time when microbiota from the external environment will also colonize the seedling host, leading to shifts in microbial community structure during seedling ontogeny. ENDOSHIFT will explore patterns of microbial succession over plant ontogeny, and how environmental conditions change microbial assemblages and dynamics while providing a fundamental knowledge base on bacterial and fungal taxa associated with roots and leaves. ENDOSHIFT will ultimately lead to a better grasp of the influence of plant-associated microbiota on the host fitness and on our ability to predict plant establishment and regeneration in natural heterogeneous ecosystems.
Forest hunting pressure interaction with forest logging over the north of French Guiana: a GPS tracking survey coupled with a spatialized bioeconomic modelling.
Guillaume Salzet, ECOFOG
Since Redford’s ‘Empty Forest’ early warning about defaunation consequences on tropical forests, many studies focused exclusively on ecological part of the complex interaction between game species, forests and human activities. Most of these studies uncovered altered ecosystems functions linked to declining animal populations, and thus conclude to improve fauna conservation. However, this conservation goal which includes interactions between industrial sectors generating hunting facilitation and hunter rationality in dispersal have received much less attention. The project ‘ForHunt Logging’, proposes to partially compensate for this lack in French Guiana. More specifically, the project aims to facilitate hunting through logging, with the innovation taking into account the rationality of hunters in their dispersal in the forest. At the end, the project aims to estimate the spatial distribution of the impact of hunting on northern in French Guiana in connection with forest planning in these areas. The results of this project will provide new knowledge in wildlife conservation suitable for facilitation due to logging, as well as maps of defaunation status which is an essential factor in tropical forest studies.
Genomics of ENdotrophy in Amphibians
Antoine Fouquet, EDB
Endotrophic larval development (without external food supply) eliminates the exotrophic aquatic larval phase that is conventionally found in most amphibians. This adaptation opened the way for the colonization of a diversity of terrestrial niches and had a key role in the evolution of amphibians. However,the genomic and molecular mechanisms of endotrophy remain largely unknown. Moreover, populations of the A. baeobatrachus complex with distinct larval development patterns coexist in sympatry in French Guiana. The project GENA proposes to take advantage of this particularly privileged model to identify candidate genes involved in the key adaptive switch between exo- and endotrophy. This project will pave the way for a great deal of potential research that will explore the genetic mechanisms and evolutionary consequences underlying the repeated acquisition of endotrophic development in amphibians using the ideal framework provided by Anomaloglossus.
Origin and Adaptation of parasites to new environments: the case of monkey malarial agents in French Guiana
Virginie Rougeron, MiVEGEC
Zoonotic malaria is an increasing public issue all around the world, questioning thepossibility for malaria elimination. One very well-known illustration of this zoonoticpotential is found in Asia with Plasmodium knowlesi a species thought to be confined tomacaques and that is now considered as a human malaria parasite. The ORA project aims to get clues on how P. simium and P. brasilianum emerged in Americas. Since to understand the origin of a pathogen species into a new hostenvironment, it is necessary to determine the set of host species in which the pathogennaturally circulates, the first task of the project will be to proceed to a more thoroughexamination of the natural host range of P. simium and P. brasilianum in American nonhumanprimates. The second task, based on genomes sequencing data, will be to study thepopulation genetic structure of these Plasmodium species in America and more specificly in French Guiana. Finally, the last task will aim to examine lineage specific genomic features of these monkey Plasmodium species to determine if and how these parasites genetically adapted to its different host species.
Occurrence and role of termites / fungi associations
Veronique Eparvier, ICSN
It was showed by our team during studies of chemical interactions between mutualistic microorganisms and their macroscopic host (termites), that termites in French Guiana could be frequently associated with Pseudallescheria sp. fungi. Several of these strains were studied by targeted metabolomic approaches and it was shown that they produced antifungal specialized metabolites. Based on this previous work, the project ORTEFA will answer several questions. First, researchers will determine how often and at what magnitude does Pseudallescheria sp. occur associated with termites in French Guiana. Then, they will try to understand what are the genetic and metabolic differences between these strains associated with termites but also how Pseudallescheria sp. strains are diffused in the environment and how this fungi was transmitted during termites evolution.
Deciphering the coastal pathobiome in French Guiana coastal waters
Jean-Christophe Auguet, MARBEC
Infectious Diseases and antimicrobial resistances (AMR) affecting human and wildlife (including domesticated animals and livestock) are a significant and growing threat to health, economy, resources and biodiversity on a global scale. Most research has focused on inland systems with comparatively little efforts directed towards marine habitats. However, the risk linked to marine habitats is a major world health and food production challenge. In French Guiana coastal controls have shown worsening water quality leading to the closure of several public beaches. The project PAMELA is a pilot study whose aim is to estimate the distribution of marine human and wildlife pathobiome and resistome (both planktonic and benthic) in 6 contrasted areas of the Frencg Guiana coast and to understand their environmental and/or anthropogenic drivers.
A first glimpse into Pleistocene ecosystems of French Guiana
Pierre-Olivier Antoine, ISEM
Until recent years, French Guiana was a terra incognita for palaeontologists… Despite their paleontological potential, Pleistocene coastal formations and fluvial terraces had not yet yielded any fossil specimens. The TIMESPAN project will exploit two recent and incidental palaeontological discoveries of utmost importance. The first discoverie come from the Centre Spatial Guyanais (ELA4, documenting ~125 ka-old species-rich marine assemblages and 40–12 ka-old fluvial-terrestrial fossils) and second one is from Atouka, near Maripasoula in the Parc Amazonien de Guyane where has been discovered well-preserved specimens of the giant ground sloth Eremotherium found in late 2020, and associated specimens. TIMESPAN will provide key information on the earliest Pleistocene ecosystems in Guyana, first-hand data on paleo-biocenoses and landscapes, and details on their spatio-temporal dynamics during the last time period devoid of any human disturbance.