Thesis : Interspecific and intraspecific variability in physiology among the toxic diatoms Pseudo-nitzschia: influence of life cycle
Thesis supervisor: Pr Pascal Claquin
Scientific supervisor: Dr Juliette Fauchot
Project: Some marine diatoms of the Pseudo-nitzschia genus (Stramenopiles, Bacillariophyceae) produce domoic acid, a neurotoxin. The accumulation of this toxin in food webs poses a threat to human health and shellfish industries and fisheries. Physiological responses of different Pseudo-nitzschia species to environmental factors are still difficult to predict, hindering the understanding of these toxic blooms. The importance of inter-specific and intra-specific variability in physiological responses is still poorly understood and life cycle also appears to influence the physiology of these diatoms, through cell size changes. Diatoms, because of their unique division mode, are characterized by a decrease in cell size during their vegetative growth phase. Cell size is restored through sexual reproduction. Few information actually exists on the influence of life cycle on diatom cell physiology. This project proposes to characterize the inter-specific and intra-specific diversity in the Pseudo-nitzschia genus. The main objectives are: 1) to study sexual reproduction processes for four species and to produce strains at different stages of the life cycle and 2) to estimate different physiological indices (growth rate, photosynthetic parameters, constants for nutrient absorption, domoic acid production) for different strains of each species at different stages of the life cycle. The specific physiological indices developed will help parameterize models of Pseudo-nitzschia dynamics and toxin production. This project will also provide innovative results on intra-specific diversity in diatoms and the influence of their peculiar life cycle on cell physiology.
Candidate profile: The candidate should have studied marine biology or plant ecophysiology with experience in marine environment. The candidate should show an interest in microalgae ecology and physiology and in laboratory studies. Some experience in culture of microalgae is required.
The selected candidate will apply to the « concours d’attribution des allocations de recherche » of the EdNBISE (Ecole doctorale Normande de Biologie Intégrative, Santé et Environnement - EdN BISE 497). The quality of academic records will therefore be taken into account for the candidate selection.
Application deadline: 15 mai 2015
Contact BOREA :
Juliette Fauchot : juliette.fauchot@unicaen.fr
Pascal Claquin : pascal.claquin@unicaen.fr
