Dynamics of microbiota and Fusarium spp. responsible for Fusarium head blight and implications for biocontrol strategies
Toan Bao Hung Nguyena, Amandine Henri-Sanvoisina, Jérôme Mouniera, Flora Penseca, Gaétan Le Flocha, et Adeline Picota
a- Univ Brest, INRAE, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, F-29280, Plouzané, France
Fusarium Head Blight is a devasting disease in cereals caused mainly by Fusarium spp. (Fspp). Despite being primary inoculum sources, soil and crop residues have been less studied than grains. Knowledge of the diversity and dynamics of microbiota and Fspp populations in these compartments is relevant to elaborate efficient biocontrol strategies. Six min-till wheat fields were thus monitored for two years, with soil, maize residues, and wheat grains collected at four stages, before metabarcoding using 16S, ITS2, EF1α markers, and qPCR using Fspp-specific primers. F. graminearum (Fg) and F. avenaceum were dominant in both grains and residues. Despite similar Fspp loads in residues in both years, grains of 2021 were more severely infected than in 2022, most probably because of less conducive conditions (drier and hotter) at flowering for Fspp. Following metabarcoding, co-occurrence network analyses revealed significant negative correlations between Fg and Epicoccum nigrum as well as Sphingomonas sp.. In parallel, a collection of 1635 bacterial and fungal isolates from collected samples was built using two methods (culture on classical media or after confrontation with Fg using the double layer method). High throughput screening of their anti-Fg activities on wheat grain-based medium, followed by a taxonomic identification of positive isolates, is in progress and shows a high prevalence of Trichoderma spp. in soil, and the presence of Epicoccum spp. to a lesser extent.
Effects of ochratoxin A and fumonisin B1 on human cells: innovative in vitro models
Beatriz Arce-Lópeza, Monika Cotona, Emmanuel Cotona, Nolwenn Hymerya
a- Univ. Brest, INRAE, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne (LUBEM UR3882)/UBO, F-29280 Plouzané, France. firstname.lastname@example.org
Mycotoxins are a group of naturally occurring fungal metabolites that contaminate a huge variety of crops worldwide, especially cereals. Ochratoxin a (OTA) and fumonisin B1 (FB1) are frequent contaminants in the food chain . The current climate change scenario may also alter human exposure to emerging mycotoxins or co-occurrence. The main health concern is related to their toxicity potential in co-exposure , and various regulations have been put in place to reduce human exposure .
To explore this, in vitro toxicological approaches [4,5] have been developed to determine the real response of mixtures in human hepatic (HepaRG) and intestinal (Caco-2) cell lines. In this context, the present work aimed to determine mycotoxin cytotoxicity using 2D (monolayer cultures), 3D (spheroids) and a transwell cell co-culture system. Cytotoxicity was determined using the MTS assay with 0.1 to 247.6 μM OTA and 0.07 to 138.5 μM FB1 concentrations after 48 h exposure. For bioavailability, Caco-2 and HepaRG cells were seeded individually in 96-well plates, while co-cultures were performed in Transwell plates.
The obtained results showed that HepaRG cells were more sensitive than Caco-2 cells, and an increase in HepaRG viability was observed in co-culture with Caco-2 cells compared to HepaRG alone. At all tested concentrations and for each model, differentiated cells were more sensitive than undifferentiated ones, except for OTA as undifferentiated HepaRG cells were more sensitive. For FB1, both cell lines presented similar values.
In this contribution, we will present preliminary results of the funded project “MYVITOX” (European Union´s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 899546).
Cis-régulation et cas non résolus de pathologies liées au gène CFTR
Clara Blotas1,Mégane Collobert1, Anaïs Le Nabec1, Claude Férec1 et Stéphanie Moisan1,2
Les polyazacycloalcanes, de par leurs remarquables propriétés de chélation du Cu(II), voient leur utilisation s’accroître pour le diagnostic et la thérapie ciblée des cancers. Parmi eux, le TE1PA, un cyclam fonctionnalisé par un groupe picolinate développé par notre équipe, forme un complexe extrêmement stable et inerte in vivo avec le Cu(II).1 Son dérivé bifonctionnel, c’est-à-dire porteur d’une fonction supplémentaire destinée à son couplage à un anticorps, a permis l’obtention d’un radiopharmaceutique efficace pour imager le myélome multiple (Figure 1, gauche).2 La technique, qui utilise une fonction de couplage isothiocyanate, reste cependant perfectible notamment au niveau de sa polyvalence.
Figure 1 : Radiopharmaceutique à base de TE1PA existant (gauche). Synthèse de nouveaux radiopharmaceutiques à partir d’un dérivé de TE1PA porteur d’un alcyne (droite).