Local European cultivars as sources of durable scab resistance in apple

The Vf resistance gene has been widely used in apple breeding programmes to control Venturia inaequalis, the causal agent of scab, the major apple disease. Since the appearance of new strains that are able to overcome this major gene, research in Europe has been focused on durable resistance. The objective of one task of the European DARE project was to find cultivars which show a broad spectrum of resistance to the different scab races. This collaborative work involved 6 partners who tested 36 cultivars with various local scab inocula collected in the participating countries and with 8 monoconidial strains belonging to known races or isolated and characterized in the frame of the DARE project. Tests were performed each year from 1998 to 2001. Symptoms were assessed using macroscopic scoring scales. Some microscopic observations were performed; these resulted in a better knowledge of the host/pathogen interaction. Very diverse and complex resistance behaviours were found: the cultivars which showed the widest range of resistance were mostly local cultivars and some newly selected hybrids combining major genes and partial resistance. It would be worthwhile to include these individuals as parents in apple breeding programmes to improve the durability of scab resistance. Some methodologies and strategies to reach this goal will be proposed

EU-Projekt:Dauerhafte Apfel-Resistenz in Europa (DARE)

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Organoids-based High Content Screening in Oncology

International audienceTo analyze the phenotypic consequences of genetic perturbation in mammalian cells with drugs, RNAi or expression vectors, there are increasing needs for systematic cell-based high content screening (HCS) approaches, particularly in oncology. Although several groups are performing HCS in human cell lines, the real challenge in translational research remains screening on a reduced number of primary cells directly obtained from patients in a microenvironment that would resemble the original tissues. While standard monolayer two-dimensional culture conditions or even spheroids resulting form the forced aggregation of cells are poor mimics of the tumour natural history, microfabricated systems enable three-dimensional clonal organoids cultures and have the potential to provide biological insight not achievable before. We use microfluidics and MEMS (MicroElectroMechanical Systems) to analyze the phenotypic consequences of genetic perturbations (RNAi-based HCS) in 3D organoids. Specifically, we present a novel approach based on a flowfocusing microfluidic system that encapsulates either single prostatic or mammary cell in Matrigel beads and assay for development of organoids. Furthermore, we developed new imaging technology to monitor live organoids self-assembly and inter organoids cell trafficking

Continuous microcarrier-based cell culture in a benchtop microfluidic bioreactor

International audienceMicrofluidic bioreactors are expected to impact cell therapy and biopharmaceutical production due to their ability to control cellular microenvironments. This work presents a novel approach for continuous cell culture in a microfluidic system. Microcarriers (i.e., microbeads) are used as growth support for anchorage-dependent mammalian cells. This approach eases the manipulation of cells within the system and enables harmless extraction of cells. Moreover, the microbioreactor uses a perfusion function based on the biocompatible integration of a porous membrane to continuously feed the cells. The perfusion rate is optimized through simulations to provide a stable biochemical environment. Thermal management is also addressed to ensure a homogeneous bioreactor temperature. Eventually, incubator-free cell cultures of Drosophila S2 and PC3 cells are achieved over the course of a week using this bioreactor. In future applications, a more efficient alternative to harvesting cells from microcarriers is also anticipated as suggested by our positive results from the microcarrier digestion experiments