Category: Events & Seminars

(Français) PhD defense of Nicolas Bajeux

Sorry, this entry is only available in French.

PhD Defense – Ghjuvan GRIMAUD -14/06/16 @ 14h – LOV

Tuesday June 14th. 2016at 02:00 pm – in Laboratoire d’Océanographie de Villefranche-sur-Mer (LOV)

Title : Automation and optimization of a device designed to improve the performance of microalgae for energy purposes by continuing selection pressure.

Abstract : Unicellular photosynthetic organisms forming the phytoplankton are the basis of primary production. Because these organisms cannot regulate their inner temperature, the medium temperature strongly constrains their growth. Understanding the impact of this factor is topical in a global change context. In this PhD thesis we have investigated how phytoplankton adapts to temperature. By analyzing the growth rate as a function of temperature for hundreds of species we highlighted the characteristics that can be accurately described by a mathematical model. We have identied the links between the cardinal temperatures as well as their thermodynamical fundament using the mechanistic Hinshelwood model. We then challenged the Eppley hypothesis “hotter is faster” for 5 phylogenetic phytoplankton groups and determined the evolutionary limits for each of them. We have also studied the adaptation mechanisms associated to long term temperature variations by developing an evolutionary model using the adaptive dynamics theory allowing to predict
the evolutionary outcome of species adaptation to a simple temperature cycle. Our results have been compared to a selection experiment carried out in a controlled device on Tisochrysis lutea. Our method has been extended to predict the adaptation of a strain to periodic temperature profiles and study phytoplankton adaptation at the global ocean scale. In situ data of sea surface temperature have been used as a forcing variable and have permitted to show that the elevation of temperature will be critical for several species in particular for those living in areas where the annual temperature fluctuation is high such as the Mediterranean sea.

Jury members :

  • JM GUARINI, UPMC, Banyuls sur Mer
  • Jean-Pierre GATTUSO, CNRS/UPMC, LOV
  • Jef HUISMAN, University of Amsterdam
  • JC POGGIALE, OCEANOMED – Campus de Luminy

PhD defense: Elsa ROUSSEAU – 27/05/16 @ 13h30 salle Euler Violet

Titel: Effect of genetic drift and selection on plant resistance durability to viruses.

Plants can be fully protected from their pathogens when they carry major resistance genes, but the efficiency of these genes is limited by the emergence and spread of adapted, resistance-breaking pathogen variants. This thesis studies how evolutionary forces imposed by the plants on pathogen populations may increase the durability of major resistance genes. Using plant viruses as a biological model, this thesis investigates the effect of genetic drift and selection, from the within-host to the host population level. Firstly, a stochastic epidemiological SI model at the field level showed that genetic drift could be particularly beneficial for crop yield when the fitness cost associated with virus adaptation to resistance was intermediate in susceptible plants. Then, the design and validation of a mechanistic-statistical model based on deterministic Lotka-Volterra equations and stochastic Dirichlet-multinomial processes allowed to disentangle the effects of genetic drift from those of selection on temporal data of within-host competition between virus variants. The intensities of genetic drift and selection acting on virus populations were shown to be controlled genetically by the hosts. Finally, a correlation analysis between these estimations of genetic drift and selection intensities and an experimental estimation of the durability of a major resistance gene showed that strong genetic drift during the early stages of plant infection led to an increase in resistance durability. These results open new perspectives for more durable management of plant resistance, by breeding plant varieties inducing strong genetic drift on pathogen populations

Jury members:

Fernando GARCIA ARENAL, Universidad Politécnica de Madrid

Frédéric HOSPITAL, INRA

Elisabeta VERGU, INRA

Christian LANNOU, INRA

Gaël THEBAUD, INRA

Alain VIARI, Inria

Jean Luc GOUZE, Inria

Frédéric FABRE, INRA

Keywords: genetic drift, selection, resistance durability, experimental evolution, epidemiology.

Soutenance de Thèse de Doctorat de HUBERT BONNEFOND au LOV le 9 Décembre 2015

HUBERT BONNEFOND soutiendra sa thèse de doctorat intitulée “Amélioration de microalgues à vocation énergétique par pression de sélection continue

le 09 décembre 2015 au Laboratoire d’Océanographie de Villefranche-sur-mer

devant le jury composé de:

  • Jean-Paul CADORET (Rapporteur)
  • Tomas MORRISONOTTO (Rapporteur)
  • Gael BOUGARAN (Examinateur)
  • Louis CHEVIN (Examinateur)
  • Patrick MAYZAUD (Examinateur)
  • Alice GUEUDET (Examinateur)
  • Olivier BERNARD (Directeur)
  • Antoine SCIANDRA (Directeur)

 microalgues

Résumé:

Le monde fait face à une crise environnementale sans précédent, due à l’action toujours plus marquée de l’homme sur son milieu. Depuis le début de l’ère industrielle, l’utilisation massive des énergies fossiles a provoqué un dérèglement climatique planétaire. Les microalgues offrent la possibilité de produire des biocarburants avec une empreinte carbone réduite, mais nécessitent encore de nombreuses améliorations pour être économiquement viables. Une de ces améliorations, à l’instar de l’agriculture moderne, réside dans la sélection de souches plus productives. Dans ce travail de thèse, nous avons développé la sélection par pression continue qui consiste à utiliser les processus de l’évolution pour faire émerger des populations d’intérêt.
Une première voie explorée a cherché à utiliser la température, paramètre crucial de la croissance des microalgues, comme moteur de sélection. En soumettant une culture à des variations diurnes de température durant une année, nous sommes parvenus à adapter une souche de Tisochrysis lutea à une gamme de températures plus large, la rendant donc plus tolérante aux variations ce paramètre.
La seconde voie a cherché à accroitre la capacité de Cylindrotheca closterium à emmagasiner ou au contraire mobiliser son azote intracellulaire, propriété physiologiquement liée à sa capacité à produire des lipides. En forçant une population de microalgues à s’adapter à des apports discontinus d’azote (succession d’états de satiété et de carence), il a été possible de sélectionner les individus les plus riches en lipides.
Enfin, nous avons modifié l’appareil pigmentaire de Tisochrisis lutea pour la rendre plus transparente à la lumière. En soumettant cette espèce à une succession de chocs lumineux, il a été possible de sélectionner les individus possédant les antennes photosynthétiques les plus petites, permettant une productivité accrue.

Philipp Hartmann’s PhD defense- 14/04/14

PhD defense “Effect of hydrodynamics on light utilization in large scale cultures of microalgae” by Philipp HARTMANN, Wednesday May 14th @ 14H00 in Salle Trégouboff, OBSERVATOIRE OCEANOGRAPHIQUE, STATION ZOOLOGIQUE, Villefranche sur mer

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52nd IEEE Conference on Decision and Control

The 52nd IEEE Conference on Decision and Control will be held Tuesday through Friday, December 10-13, 2013 at Palazzo dei Congressi, Florence, Italy. Pre-conference Workshops will be held on Monday December 9, 2013.

NOLCOS 2013: Sept 4-6, 2013, Toulouse (France)

NOLCOS 2013: Sept 4-6, 2013, Toulouse (France)

[http://conf.laas.fr/NOLCOS2013/]

2012 IEEE 51st Annual Conference on Decision and Control (CDC)

Hawaii December 10-13, 2012

The conference discusses advances in theory, design and application of control systems.

link to CDC conference