Ecology of sandy beaches: where we are, where do we want to go


 Olivier Troccaz    05/06/2019 : 09:07

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07/06/19 - Séminaire de Lucia FANINI (Hellenic Centre for Marine Research)

Le vendredi 7 juin 2019 à 13h00, salle de conférences de l'OSUR, bâtiment 14b, Campus de Beaulieu, UR1

Ecology of sandy beaches: where we are, where do we want to go

Abstract: Sandy beaches are ecotonal systems connecting land and sea, and subjected to a continuous flow of energy and material, shaping them into morphotypes. Resident beach macrofauna share basic adaptations to cope such environment, but also, macrofauna communities are shaped by the physical constraints related to morphotypes. Current ecological paradigms explain such basic patterns. However, increasing human impacts -including coastal squeeze- urgently call for a change in approach, putting forward sandy beaches as a representative case of social-ecological systems and proposing integrated knowledge to achieve sustainability. The seminar will mention case-studies and possible further research directions as presented in the last International Sandy Beach Symposium (2018)

Contact: Lucia FANINI


Behavioral, physiological and molecular basis of insecticide resistance in an invasive insect Alphitobius diaperinus (Tenebrionidae) in agro-ecosystem - Temporal expression of chaperome-related genes in Drosophila melanogaster exposed to thermal stress



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24/05/19 - Séminaires de Kevin NOORT et Sapho-Lou MARTI

Le vendredi 24 mai 2019 à 13h00, salle B. AUVRAY, bâtiment 15, Campus de Beaulieu, UR1

Behavioral, physiological and molecular basis of insecticide resistance in an invasive insect Alphitobius diaperinus (Tenebrionidae) in agro-ecosystem - Kevin NOORT

Abstract: Alphitobius diaperinus (Tenebrionidae) is a cosmopolitan pest insect that reduces livestock profits and animal welfare in the poultry farming industry. Firstly, by feeding on chicken feed, weakened chickens and carrion, and effectively reducing poultry weight gain; secondly, by transmitting viruses and pathogens within flocks, among flocks and towards costumers; and lastly, by destroying wall and isolation material of broiler facilities. The conventional method of controlling A. diaperinus populations is by spraying organophosphate or pyrethroid insecticides on the ground and walls when the facility is empty. At a broiler farm near Rennes, this method has been used consistently for 20+ years using the pyrethroid ß-cyfluthrin, during which the beetle population developed resistance against this insecticide. In order to determine the biochemical and behavioral mechanisms by which the resistance is attained, this resistant population, called Mainfray, was compared with a susceptible population, called Envie. These populations were studied on the enzymatic activity of glutathione-s-transferase (GST), cytochrome P450 (P450), non-specific esterase (nsE) and on acetylcholinesterase insensitivity (AChE). These beetles were pre-exposed to indicated concentrations of ß-cyfluthrin or control for 24 hours, after which they were frozen for later biochemical testing. The enzymatic activity was determined for 12 replicates per group, with 3 individuals per replicate. Behavior was assayed by recording 4 beetles for 10 minutes in arenas that were half-treated or untreated with ß-cyfluthrin. Behavior was later quantified using the BEMOVI tracking tool. Our findings show that Mainfray beetles have increased enzymatic activity of GSTs and P450s enzymes compared to Envie beetles. Furthermore, Mainfray’s enzymatic activity of acetylcholinesterase, both inhibited and uninhibited, is also increased. Results of the behavioral analysis are forthcoming, however, there does not seem to be a difference between Envie and Mainfray behavior.

Contact: Kevin NOORT

Temporal expression of chaperome-related genes in Drosophila melanogaster exposed to thermal stress - Sapho-Lou MARTI

Abstract: All organisms have mechanisms to resist environmental insults (biotic or abiotic stress). When exposed to stress, cells activate the expression of a particular class of proteins called heat shock proteins (HPSs). The role of these chaperones is to repair damaged proteins (unfolded) by stress or to coordinate their degradation. This mechanism of protection is extremely conserved through evolution from bacteria to humans. The "CHAPEROME" corresponds to all molecular chaperones and co-chaperones that interact in a complex network to ensure cellular homeostasis and the proper functioning of the proteome. The functions of the main and most common chaperones (eg Hsp70 or Hsp90) are quite well known, but functions and expression patterns of the many other chaperones remain very little studied. In addition, the integrative dynamic network of chaperome in response to stress is poorly characterized. Little is known about the whole chaperome reactions even in model organisms. In this project, we studied the temporal expression of 135 D. melanogaster chaperome-related genes over the course of a heat and cold stress exposure and recovery. Increased or decreased expression in many genes was found in response to stress, with differences according to the stress nature (cold or hot). In both cases, we observed peaks of expression of many genes 2 hours after the stress. The most responsive genes in both stress were quite similar, showing a common response to thermal stress. We also identified several genes specifically responding to either cold or heat, showing dissimilarity of the stress response networks between heat and cold stress.

Contact: Sapho-Lou MARTI


Matières organiques dissoutes, nutriments et interactions avec les communautés microbiennes hétérotrophes



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17/05/19 - Séminaire de Thibault LAMBERT (Université de Lausane)

Le vendredi 17 mai 2019 à 13h00, salle de conférences de l'OSUR, bâtiment 14b, Campus de Beaulieu, UR1

Matières organiques dissoutes, nutriments et interactions avec les communautés microbiennes hétérotrophes

Résumé : Les matières organiques dissoutes (MOD) jouent un rôle majeur sur le fonctionnement écologique et biogéochimique des écosystèmes aquatiques, notamment car elles sont source de carbone et d’énergie pour les communautés microbiennes hétérotrophes. L’activité de ces dernières est cependant aussi influencée par les concentrations en autre macronutriments tels que l’azote et le phosphore, mais les interactions entre MOD – nutriments et leurs effets sur le métabolisme des écosystèmes aquatiques est peu connu. Via des approches couplées de terrain et d’expériences en laboratoire, les liens entre MOD, nutriments et communautés microbiennes ont été étudiés dans le bassin du lac Léman entre différents écosystèmes aquatiques (lac et rivières) ainsi qu’à leurs interfaces. Nous nous intéresserons plus particulièrement lors de ce séminaire à l’influence des activités humaines sur les traits fonctionnels des communautés microbiennes en lien avec les changements de concentration et de composition des MOD et des nutriments et à la dégradation des MOD aux interfaces lac/rivière.

Contact : Thibault LAMBERT


Etude des mécanismes physiologiques sous-jacents à la plasticité de la thermotolérance chez la drosophile invasive Drosophila suzukii



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17/05/19 - Soutenance de thèse de Thomas ENRIQUEZ

Le vendredi 17 mai 2019 à 14h00, salle des thèses, bâtiment 1, Campus de Beaulieu, UR1

Etude des mécanismes physiologiques sous-jacents à la plasticité de la thermotolérance chez la drosophile invasive Drosophila suzukii

 

Jury :
Maryvonne CHARRIER (directrice de thèse, Univ Rennes1, ECOBIO)
Hervé COLINET (co-directeur, Univ Rennes1, ECOBIO)
Cristina VIEIRA-HEDDI (rapporteur, UCBL, LBBE)
Thierry HANCE (rapporteur, Université Catholique de Louvain, ELI)
Claudia WIEGAND (examinatrice, Univ Rennes1, ECOBIO)
Sylvain PINCEBOURDE (examinateur, Univ Tours, IRBI)

Résumé : Drosophila suzukii est une drosophile invasive en Europe, Amérique du Nord et Amérique du Sud. Contrairement aux autres espèces de drosophiles, les femelles parasitent les fruits mûrs que les larves consomment, engendrant d’importants dégâts sur les cultures fruitières. Les stratégies mises en place par cette espèce pour tolérer les températures hivernales sous nos latitudes sont encore peu comprises. Par conséquent, l’objectif de ma thèse était d’acquérir des connaissances fondamentales sur la thermotolérance de cette espèce, en m’intéressant notamment à la plasticité de la tolérance au froid et aux mécanismes physiologiques sous-jacents à l’acclimatation. J’ai évalué la thermotolérance basale de D. suzukii en soumettant des adultes et des pupes à un large panel de températures (froides et chaudes). Ces expérimentations ont permis de confirmer que cette espèce était intolérante au froid et que des températures supérieures à 32°C impactaient grandement sa survie. Par la suite, j’ai évalué la plasticité de sa tolérance au froid. Mes travaux ont permis de confirmer que sa thermotolérance était effectivement plastique, puisque l’utilisation de températures fluctuantes ou l’acclimatation permettaient de réduire sa mortalité lors d’expositions aux basses températures. L’acclimatation chez D. suzukii était corrélée à de nombreuses modifications physiologiques, telles que l’accumulation de cryoprotecteurs, un réajustement de la composition des phospholipides membranaires et des réserves lipidiques, une régulation des gènes liés à l’activité des transporteurs ioniques ainsi qu’un maintien de l’homéostasie métabolique. Ces modifications, également observées chez d’autres espèces d’insectes, pourraient être liées à l’augmentation de la tolérance au froid de D. suzukii, jouant probablement un rôle important dans sa survie hivernale et donc dans le succès de son invasion. Ces connaissances acquises sur sa thermobiologie contribueront sans doute à mieux cerner les limites physiologiques de cette espèce et prédire l’évolution de son invasion, ainsi que sa phénologie et les variations de populations au cours des saisons dans les zones déjà envahies. Mes résultats ouvrent également des perspectives intéressantes pour la mise en place de techniques de lutte intégrée contre D. suzukii.

Contact: Thomas ENRIQUEZ


Development of Trichoderma bio-organic fertilizers to ensure high yields and high quality of crops - Linkage of nature disease suppressive soil microbiota to soil microbiome manipulation



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10/05/19 - Séminaires de Qirong SHEN et Rong LI (College of Resources & Environmental Sciences, Nanjing Agricultural University (China))

Le vendredi 10 mai 2019 à 13h00, salle de conférences de l'OSUR, bâtiment 14b, Campus de Beaulieu, UR1

Development of Trichoderma bio-organic fertilizers to ensure high yields and high quality of crops

Linkage of nature disease suppressive soil microbiota to soil microbiome manipulation

Summary: Effects of Trichoderma spp on promotion of plant growth and on biological control of soil borne diseases are much more significant than Bacillus spp. However, it is more difficult to make Trichoderma bioorganic fertilizers than Bacillus bioorganic fertilizers. The presentation introduces the steps of how to make Trichoderma bioorganic fertilizers. The functional mechanisms of Trichoderma spp will also be addressed in the presentation.

Prof SHEN is interested in the research of bioorganic fertilizers and soil microbiology. So far he has published more than 450 SCI papers and his H-index in Google scholar is 65. He is now the director of Academic Committee of Nanjing Agricultural University. He is a chief scientist of some national projects.

Summary: Banana production is now is severely hampered by Panama disease, a soil-borne wilt caused by the fungus Fusarium oxysporum f. sp. cubense race 4 (Foc4). We first compared soil microbiota in banana planting soils with different monoculture years to reveal the microbial characters associated with the increased disease. Then, the 6 disease suppressive soils were observed and the micobiota in these soils were analyzed to decipher the underlying mechanism involved in the disease suppression. At last, bio-organic fertilizer and its components were used in the high diseased soil to reveal the underlying mechanism involved in the recovery of disease suppression ability associated with the soil microbiota manipulation.

Rong LI, Associate Professor, Vice Dean of the College, College of Resources and Environmental Sciences, Nanjing Agricultural University. He focuses on the following research areas: agricultural waste disposal, organic fertilizer and bioorganic fertilizer development, and soil borne disease suppression. The main aim is to decipher the biological processes involved in the above topics. He published more than 40 SCI paper as first author of Corresponding author.