Position-referenced microscopy for live cell culture monitoring

Position-referenced microscopy (PRM) is based on smart sample holders that integrate a position reference pattern (PRP) in their depth, allowing the determination of the lateral coordinates with respect to the sample-holder itself. Regions of interest can thus be retrieved easily after culture dish transfers from a cell incubator to the microscope stage. Images recorded at different instants in time are superimposed in a common coordinate system with subpixel accuracy. This paper presents such smart Petri culture dishes and their use for live cell culture monitoring. The impact of the PRP on the light budget is discussed and performances are demonstrated. First results on the application of PRM to the observation of apoptotic body internalization are reported

Anti-cancer effects of isoliquiritigenin : model of cervical cancer

Le cancer du col de l'utérus est le troisième cancer le plus fréquent chez la femme dans le monde. Cependant l'efficacité des traitementsconventionnels n'est pas toujours optimale. La recherche de nouvelles molécules naturelles, possédant des propriétés anticancéreuses et n'induisantpas d'effets secondaires, est donc d'un intérêt majeur. Parmi ces molécules, un flavonoïde se distingue des autres par ses nombreux effetsthérapeutiques potentiels, l'isoliquiritigénine (ILG). Cette chalcone naturellement présente dans la racine de réglisse, possède de nombreusespropriétés, incluant une activité anti-tumorale.Le but de cette thèse était d'étudier l'effet anticancéreux de ITLG synthétique dans des cellules dérivées de cancer du col de l'utérus.L'étude du mécanisme moléculaire impliqué dans Papoptose a été centrée sur les cellules les plus représentatives des carcinomes du col de l'utérus,les Ça Ski infectées par le papillomavirus de type 16 dans lequel nous démontrons que l'ILG inhibe l'expression de l'oncogène viral E6 d'HPVlô.Nos résultats montrent que l'ILG diminue la viabilité, induit un arrêt de cycle et favorise l'apoptose dans des cellules dérivées de cancer du col del'utérus différant par leur statut viral et leur statut p53.Nous mettons ainsi en évidence que l'apoptose induite par l'ILG est spécifique des cellules tumorales et implique différentes voies de signalisationsuivant le type cellulaire. L'ILG pourrait donc faire partie d'un nouvel arsenal thérapeutique visant à lutter contre le cancer du col de l'utéruCervix cancer is the third most common cancer among women Worldwide. Many treatments are already available but they are not always efficient.This is why new natural molecules with anticancer properties that could reduce the side effects of conventional therapy are investigated. Among them,isoliquiritigenin (ILG), a fiavonoid, differentiates itself through ils various potential therapeutic properties. This chalcone isolated from roots oflicorice has many properties including an anti-tumor activity.The aim of this thesis was to study anti-tumoral effects of synthetic ILG in cervical cancer cells.We show that ILG decreases viability, induces cell cycle arrest and engages apoptosis in cervial cancer cells differing one from the other by their viraland p53 status. The death induced by ILG in the HPV positive and wild-type p53 Ça Ski, SiHa and HeLa cells appears to be independant of p53 andof the mitochondria, contrary to what happens in the HPV negative mutated p53 C-33A cells, where death could be initiated by an endoplasmicreticulum stress. The molecular mechanism of apoptosis is mainly studied on HPV 16 Ça Ski cells, the most representative cells of cervical carcinoma.ILG leads to a down-regulation of the viral oncogen E6 HPV16 expression.The study of the pathways involved by ILG highlights differences according to the cellular type. As it specifically induces apoptosis on tumoral cells,ILG could act as a potential therapeutic agent in cervix cancer

Isoliquiritigenin induces caspase-dependent apoptosis via downregulation of HPV16 E6 expression in cervical cancer Ca Ski cells.

International audienceFlavonoids have antitumoral properties and may be attractive candidates as anticancer therapy. Isoliquiritigenin which is a constituent of licorice (Glycyrrhiza inflata), a plant commonly used in traditional Uyghur medicine in Xinjiang, China, was studied for antiproliferative and apoptotic activity in human cervical cancer cells, Ca Ski, SiHa, HeLa, and C-33A. Its molecular mechanism of action was specifically examined in Ca Ski cells. Isoliquiritigenin decreased cell viability, induced cell accumulation in G2/M and morphological and biochemical features of apoptosis in the four cancer cell lines. In Ca Ski cells, isoliquiritigenin led to a downregulation of HPV16 E6 expression associated with an increase of p53 and p21 levels, enhanced expression of Bax and decreased expression of Bcl-2 and Bid proform triggering dissipation of the mitochondrial membrane potential, released cytochrome c to the cytosol followed by activation of caspase cascade with cleavage of caspase-9, caspase-3, and PARP. Caspase-8 was also cleaved. Moreover treatment with a pan-caspase inhibitor prevented apoptosis. As Ca Ski cells are representative of carcinoma naturally occurring in the cervix, our results suggest a potential benefit of isoliquiritigenin for cervical cancer prevention and treatment

A geographically diverse collection of schizosaccharomyces pombe isolates shows limited phenotypic variation but extensive karyotypic diversity

The fission yeast Schizosaccharomyces pombe has been widely used to study eukaryotic cell biology, but almost all of this work has used derivatives of a single strain. We have studied 81 independent natural isolates and 3 designated laboratory strains of Schizosaccharomyces pombe. Schizosaccharomyces pombe varies significantly in size but shows only limited variation in proliferation in different environments compared with Saccharomyces cerevisiae. Nucleotide diversity, p, at a near neutral site, the central core of the centromere of chromosome II is approximately 0.7%. Approximately 20% of the isolates showed karyotypic rearrangements as detected by pulsed field gel electrophoresis and filter hybridization analysis. One translocation, found in 6 different isolates, including the type strain, has a geographically widespread distribution and a unique haplotype and may be a marker of an incipient speciation event. All of the other translocations are unique. Exploitation of this karyotypic diversity may cast new light on both the biology of telomeres and centromeres and on isolating mechanisms in single-celled eukaryotes