Genetic tool development in marine protists: emerging model organisms for experimental cell biology

Abstract: Diverse microbial ecosystems underpin life in the sea. Among these microbes are many unicellular eukaryotes that span the diversity of the eukaryotic tree of life. However, genetic tractability has been limited to a few species, which do not represent eukaryotic diversity or environmentally relevant taxa. Here, we report on the development of genetic tools in a range of protists primarily from marine environments. We present evidence for foreign DNA delivery and expression in 13 species never before transformed and for advancement of tools for eight other species, as well as potential reasons for why transformation of yet another 17 species tested was not achieved. Our resource in genetic manipulation will provide insights into the ancestral eukaryotic lifeforms, general eukaryote cell biology, protein diversification and the evolution of cellular pathways

Occurrence of mutations impairing sigma factor B (SigB) function upon inactivation of Listeria monocytogenes genes encoding surface proteins.

Bacteria of the genus Listeria contain the largest family of LPXTG surface proteins covalently anchored to the peptidoglycan. The extent at which these proteins may function or be regulated cooperatively is at present unknown. Because of their unique cellular location, we reasoned that distinct LPXTG proteins could act as elements contributing to cell wall homeostasis or influencing the stability of other surface proteins bound to peptidoglycan. To test this hypothesis, we analysed by proteomics mutants of the intracellular pathogen L. monocytogenes lacking distinct LPXTG proteins implicated in pathogen-host interactions as InlA, InlF, InlG, InlH, InlJ, LapB and Vip. Changes in the cell wall proteome were found in inlG and vip mutants, which exhibited reduced levels of the LPXTG proteins InlH, Lmo0610, Lmo0880 and Lmo2085, all regulated by the stress-related sigma factor SigB. The ultimate basis of this alteration was uncovered by genome sequencing, which revealed that these inlG and vip mutants carried loss-of-function mutations in the rsbS, rsbU and rsbV genes encoding regulatory proteins that control SigB activity. Attempts to recapitulate this negative selection of SigB in large series of new inlG or vip mutants constructed for this purpose were however unsuccessful. These results indicate that inadvertent secondary mutations affecting SigB functionality can randomly arise in L. monocytogenes when using widely used genetic procedures or during sub-culturing. Testing of SigB activity could be therefore valuable when manipulating genetically L. monocytogenes prior to any subsequent phenotypic analysis. This test may be even more justified when generating deletions affecting cell envelope components.Fil: Quereda, Juan J.. Consejo Superior de Investigaciones Cientificas. Centro Nacional de Biotecnologia; EspañaFil: Graciela Pucciarelli, M.. Consejo Superior de Investigaciones Cientificas. Centro Nacional de Biotecnologia; España. Universidad Autónoma de Madrid. Departamento de Biología Molecular. Centro de Biología Molecular "Severo Ochoa"; EspañaFil: Botello Morte, Laura. Consejo Superior de Investigaciones Cientificas. Centro Nacional de Biotecnologia; EspañaFil: Calvo, Enrique. Centro Nacional Investigaciones Cardiovasculares; EspañaFil: Carvalho, Filipe. Universidade do Porto. Instituto de Biologia Molecular e Celular. Group of Molecular Microbiology; PortugalFil: Bouchier, Christiane. Institut Pasteur. Département Génomes et Génétique. Plate-forme PF1 Génomique; FranciaFil: Vieira, Ana. Universidade do Porto. Instituto de Biologia Molecular e Celular. Group of Molecular Microbiology; PortugalFil: Mariscotti, Javier Fernando. Consejo Superior de Investigaciones Cientificas. Centro Nacional de Biotecnologia; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Chakraborty, Trinad. Justus-Liebig-University. Institute of Medical Microbiology; AlemaniaFil: Cossart, Pascale. Institut National de la Santé et de la Recherche Médicale. Unité des Interactions Bactéries-Cellules; Francia. Instituto Pasteur; Francia. Centre de Recherche de Nantes. Institut National de la Recherche Agronomique; FranciaFil: Hain, Torsten. Justus-Liebig-University. Institute of Medical Microbiology; AlemaniaFil: Cabanes, Didier. Universidade do Porto. Instituto de Biologia Molecular e Celular. Group of Molecular Microbiology; EspañaFil: Garcia del Portillo, Francisco. Consejo Superior de Investigaciones Cientificas. Centro Nacional de Biotecnologia; Españ

Definition and management of colorectal polyposis not associated with APC/MUTYH germline pathogenic variants: AIFEG consensus statement

An expert consensus panel convened by the Italian Association for Inherited and Familial Gastrointestinal Tumors (Associazione Italiana per lo Studio della Familiarit\ue0 ed Ereditariet\ue0 dei Tumori Gastrointestinali, AIFEG) reviewed the literature and agreed on a number of position statements regarding the definition and management of polyposis coli without an identified pathogenic mutation on the APC or MUTYH genes, defined in the document as NAMP (non-APC/MUTYH polyposis)