BRIT1/MCPH1 Is Essential for Mitotic and Meiotic Recombination DNA Repair and Maintaining Genomic Stability in Mice

BRIT1 protein (also known as MCPH1) contains 3 BRCT domains which are conserved in BRCA1, BRCA2, and other important molecules involved in DNA damage signaling, DNA repair, and tumor suppression. BRIT1 mutations or aberrant expression are found in primary microcephaly patients as well as in cancer patients. Recent in vitro studies suggest that BRIT1/MCPH1 functions as a novel key regulator in the DNA damage response pathways. To investigate its physiological role and dissect the underlying mechanisms, we generated BRIT1−/− mice and identified its essential roles in mitotic and meiotic recombination DNA repair and in maintaining genomic stability. Both BRIT1−/− mice and mouse embryonic fibroblasts (MEFs) were hypersensitive to γ-irradiation. BRIT1−/− MEFs and T lymphocytes exhibited severe chromatid breaks and reduced RAD51 foci formation after irradiation. Notably, BRIT1−/− mice were infertile and meiotic homologous recombination was impaired. BRIT1-deficient spermatocytes exhibited a failure of chromosomal synapsis, and meiosis was arrested at late zygotene of prophase I accompanied by apoptosis. In mutant spermatocytes, DNA double-strand breaks (DSBs) were formed, but localization of RAD51 or BRCA2 to meiotic chromosomes was severely impaired. In addition, we found that BRIT1 could bind to RAD51/BRCA2 complexes and that, in the absence of BRIT1, recruitment of RAD51 and BRCA2 to chromatin was reduced while their protein levels were not altered, indicating that BRIT1 is involved in mediating recruitment of RAD51/BRCA2 to the damage site. Collectively, our BRIT1-null mouse model demonstrates that BRIT1 is essential for maintaining genomic stability in vivo to protect the hosts from both programmed and irradiation-induced DNA damages, and its depletion causes a failure in both mitotic and meiotic recombination DNA repair via impairing RAD51/BRCA2's function and as a result leads to infertility and genomic instability in mice

Fungal diversity notes 111–252—taxonomic and phylogenetic contributions to fungal taxa

International audienceThis paper is a compilation of notes on 142 fungal taxa, including five new families, 20 new genera, and 100 new species, representing a wide taxonomic and geographic range. The new families, Ascocylindricaceae, Caryosporaceae and Wicklowiaceae (Ascomycota) are introduced based on their distinct lineages and unique morphology. The new Dothideomycete genera Pseudomassariosphaeria (Amniculicolaceae), Heracleicola, Neodidymella and Pseudomicrosphaeriopsis (Didymellaceae), Pseudopithomyces (Didymosphaeriaceae), Brunneoclavispora, Neolophiostoma and Sulcosporium (Halotthiaceae), Lophiohelichrysum (Lophiostomataceae), Galliicola, Populocrescentia and Vagicola (Phaeosphaeriaceae), Ascocylindrica (Ascocylindricaceae), Elongatopedicellata (Roussoellaceae), Pseudoasteromassaria (Latoruaceae) and Pseudomonodictys (Macrodiplodiopsidaceae) are introduced. The newly described species of Dothideomycetes (Ascomycota) are Pseudomassariosphaeria bromicola (Amniculicolaceae), Flammeascoma lignicola (Anteagloniaceae), Ascocylindrica marina (Ascocylindricaceae), Lembosia xyliae (Asterinaceae), Diplodia crataegicola and Diplodia galiicola (Botryosphaeriaceae), Caryospora aquatica (Caryosporaceae), Heracleicola premilcurensis and Neodidymella thailandicum (Didymellaceae), Pseudopithomyces palmicola (Didymosphaeriaceae), Floricola viticola (Floricolaceae), Brunneoclavispora bambusae, Neolophiostoma pigmentatum and Sulcosporium thailandica (Halotthiaceae), Pseudoasteromassaria fagi (Latoruaceae), Keissleriella dactylidicola (Lentitheciaceae), Lophiohelichrysum helichrysi (Lophiostomataceae), Aquasubmersa japonica (Lophiotremataceae), Pseudomonodictys tectonae (Macrodiplodiopsidaceae), Microthyrium buxicola and Tumidispora shoreae (Microthyriaceae), Alloleptosphaeria clematidis, Allophaeosphaeria cytisi, Allophaeosphaeria subcylindrospora, Dematiopleospora luzulae, Entodesmium artemisiae, Galiicola pseudophaeosphaeria, Loratospora luzulae, Nodulosphaeria senecionis, Ophiosphaerella aquaticus, Populocrescentia forlicesenensis and Vagicola vagans (Phaeosphaeriaceae), Elongatopedicellata lignicola, Roussoella magnatum and Roussoella angustior (Roussoellaceae) and Shrungabeeja longiappendiculata (Tetraploasphaeriaceae). The new combinations Pseudomassariosphaeria grandispora, Austropleospora archidendri, Pseudopithomyces chartarum, Pseudopithomyces maydicus, Pseudopithomyces sacchari, Vagicola vagans, Punctulariopsis cremeoalbida and Punctulariopsis efibulata Dothideomycetes. The new genera Dictyosporella (Annulatascaceae), and Tinhaudeus (Halosphaeriaceae) are introduced in Sordariomycetes (Ascomycota) while Dictyosporella aquatica (Annulatascaceae), Chaetosphaeria rivularia (Chaetosphaeriaceae), Beauveria gryllotalpidicola and Beauveria loeiensis (Cordycipitaceae), Seimatosporium sorbi and Seimatosporium pseudorosarum (Discosiaceae), Colletotrichum aciculare, Colletotrichum fusiforme and Colletotrichum hymenocallidicola (Glomerellaceae), Tinhaudeus formosanus (Halosphaeriaceae), Pestalotiopsis subshorea and Pestalotiopsis dracaenea (Pestalotiopsiceae), Phaeoacremonium tectonae (Togniniaceae), Cytospora parasitica and Cytospora tanaitica (Valsaceae), Annulohypoxylon palmicola, Biscogniauxia effusae and Nemania fusoideis (Xylariaceae) are introduced as novel species to order Sordariomycetes. The newly described species of Eurotiomycetes are Mycocalicium hyaloparvicellulum (Mycocaliciaceae). Acarospora septentrionalis and Acarospora castaneocarpa (Acarosporaceae), Chapsa multicarpa and Fissurina carassensis (Graphidaceae), Sticta fuscotomentosa and Sticta subfilicinella (Lobariaceae) are newly introduced in class Lecanoromycetes. In class Pezizomycetes, Helvella pseudolacunosa and Helvella rugosa (Helvellaceae) are introduced as new species. The new families, Dendrominiaceae and Neoantrodiellaceae (Basidiomycota) are introduced together with a new genus Neoantrodiella (Neoantrodiellaceae), here based on both morphology coupled with molecular data. In the class Agaricomycetes, Agaricus pseudolangei, Agaricus haematinus, Agaricus atrodiscus and Agaricus exilissimus (Agaricaceae), Amanita melleialba, Amanita pseudosychnopyramis and Amanita subparvipantherina (Amanitaceae), Entoloma calabrum, Cora barbulata, Dictyonema gomezianum and Inocybe granulosa (Inocybaceae), Xerocomellus sarnarii (Boletaceae), Cantharellus eucalyptorum, Cantharellus nigrescens, Cantharellus tricolor and Cantharellus variabilicolor (Cantharellaceae), Cortinarius alboamarescens, Cortinarius brunneoalbus, Cortinarius ochroamarus, Cortinarius putorius and Cortinarius seidlii (Cortinariaceae), Hymenochaete micropora and Hymenochaete subporioides (Hymenochaetaceae), Xylodon ramicida (Schizoporaceae), Colospora andalasii (Polyporaceae), Russula guangxiensis and Russula hakkae (Russulaceae), Tremella dirinariae, Tremella graphidis and Tremella pyrenulae (Tremellaceae) are introduced. Four new combinations Neoantrodiella gypsea, Neoantrodiella thujae (Neoantrodiellaceae), Punctulariopsis cremeoalbida, Punctulariopsis efibulata (Punctulariaceae) are also introduced here for the division Basidiomycota. Furthermore Absidia caatinguensis, Absidia koreana and Gongronella koreana (Cunninghamellaceae), Mortierella pisiformis and Mortierella formosana (Mortierellaceae) are newly introduced in the Zygomycota, while Neocallimastix cameroonii and Piromyces irregularis (Neocallimastigaceae) are introduced in the Neocallimastigomycota. Reference specimens or changes in classification and notes are provided for Alternaria ethzedia, Cucurbitaria ephedricola, Austropleospora, Austropleospora archidendri, Byssosphaeria rhodomphala, Lophiostoma caulium, Pseudopithomyces maydicus, Massariosphaeria, Neomassariosphaeria and Pestalotiopsis montellica