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Nuclear transfer consists in injecting a somatic nucleus carrying valuable genetic information into a recipient oocyte to sire a diploid offspring which bears the genome of interest. It requires that the oocyte (maternal) DNA is removed. In fish, because enucleation is difficult to achieve, non-enucleated oocytes are often used and disappearance of the maternal DNA was reported in some clones. The present work explores which cellular events explain spontaneous erasure of maternal DNA, as mastering this phenomenon would circumvent the painstaking procedure of fish oocyte enucleation. The fate of the somatic and maternal DNA during oocyte activation and first cell cycle was studied using DNA labeling and immunofluorescence in goldfish clones. Maternal DNA was always found as an intact metaphase within the oocyte, and polar body extrusion was minimally affected after oocyte activation. During the first cell cycle, only 40% of the clones displayed symmetric cleavage, and these symmetric clones contributed to 80% of those surviving at hatching. Maternal DNA was often fragmented and located under the cleavage furrow. The somatic DNA was organized either into a normal mitotic spindle or abnormal multinuclear spindle. Scenarios matching the DNA behavior and the embryo fate are proposed.

Evidence has highlighted the importance of immune cells in various gut disorders. Both the quantification and localization of these cells are essential to the understanding of the complex mechanisms implicated in these pathologies. Even if quantification can be assessed (e.g., by flow cytometry), simultaneous cell localization and quantification of whole tissues remains technically challenging. Here, we describe the use of a computer learning-based algorithm created in the Tissue Studio interface that allows for a semi-automated, robust and rapid quantitative analysis of immunofluorescence staining on whole colon sections according to their distribution in different tissue areas. Indeed, this algorithm was validated to characterize gut immune microenvironment. Its application to the preclinical colon cancer APCMin/+ mouse model is illustrated by the simultaneous counting of total leucocytes and T cell subpopulations, in the colonic mucosa, lymphoid follicles and tumors. Moreover, we quantify T cells in lymphoid follicles for which quantification is not possible with classical methods. Thus, this algorithm is a new and robust preclinical research tool, for investigating immune contexture exemplified by T cells but it is also applicable to other immune cells such as other myeloid and lymphoid populations or other cellular phenomenon along mouse gut.

Expression de la protéine Doppel dans les cellules de Sertoli : Impact sur la fertilité mâle chez la souris. 2. Journées Scientifiques du GdR Repro

In France since 1985, corn salad (Valerianella locusta) production has been increasing by 820 t a year and now reaches nearly 15 000 t. This increase was followed by the outbreak of a new disease in the main production area. In 1991, a pathogenic bacterium was isolated from black and greasy leaf spots. Studies based on phenotypic and genetic characteristics have been carried out to describe this new bacterium first identified as a non-fluorescent Pseudomonas (1). As Phoma valerianellae is a fungus also responsible for black leaf spots on corn salad, a reliable method of diagnosis was needed to identify the disease in routine. Immunofluorescence performed on symptoms and double-diffusion on pure cultures were tested.

[i]Erwinia amylovora[/i] : general characteristics, biochemistry and serology

Caractéristiques des souches d'Agrobacterium radiobacter variété tumefaciens isolées des pépinières