Mostrando recursos 1 - 6 de 6

  1. Stepwise evolution of the centriole-assembly pathway

    Carvalho-Santos, Z.; Machado, P.; Branco, P.; Tavares-Cadete, F.; Rodrigues-Martins, A.; Pereira-Leal, J. B.; Bettencourt-Dias, M.
    The centriole and basal body (CBB) structure nucleates cilia and flagella, and is an essential component of the centrosome, underlying eukaryotic microtubule-based motility, cell division and polarity. In recent years, components of the CBB-assembly machinery have been identified, but little is known about their regulation and evolution. Given the diversity of cellular contexts encountered in eukaryotes, but the remarkable conservation of CBB morphology, we asked whether general mechanistic principles could explain CBB assembly. We analysed the distribution of each component of the human CBB-assembly machinery across eukaryotes as a strategy to generate testable hypotheses. We found an evolutionarily cohesive and...

  2. Centrioles: active players or passengers during mitosis?

    Debec, Alain; Sullivan, William; Bettencourt-Dias, Monica
    No funding agencies or grants indicated in the publication.

  3. Drosophila melanogaster as a model for basal body research

    Jana, Swadhin Chandra; Bettencourt-Dias, Mónica; Durand, Bénédicte; Megraw, Timothy L.
    The fruit fly, Drosophila melanogaster, is one of the most extensively studied organisms in biological research and has centrioles/basal bodies and cilia that can be modelled to investigate their functions in animals generally. Centrioles are nine-fold symmetrical microtubule-based cylindrical structures required to form centrosomes and also to nucleate the formation of cilia and flagella. When they function to template cilia, centrioles transition into basal bodies. The fruit fly has various types of basal bodies and cilia, which are needed for sensory neuron and sperm function. Genetics, cell biology and behaviour studies in the fruit fly have unveiled new basal body...

  4. Distinct mechanisms eliminate mother and daughter centrioles in meiosis of starfish oocytes

    Borrego-Pinto, Joana; Somogyi, Kálmán; Karreman, Matthia A.; König, Julia; Müller-Reichert, Thomas; Bettencourt-Dias, Mónica; Gönczy, Pierre; Schwab, Yannick; Lénárt, Péter
    Centriole elimination is an essential process that occurs in female meiosis of metazoa to reset centriole number in the zygote at fertilization. How centrioles are eliminated remains poorly understood. Here we visualize the entire elimination process live in starfish oocytes. Using specific fluorescent markers, we demonstrate that the two older, mother centrioles are selectively removed from the oocyte by extrusion into polar bodies. We show that this requires specific positioning of the second meiotic spindle, achieved by dynein-driven transport, and anchorage of the mother centriole to the plasma membrane via mother-specific appendages. In contrast, the single daughter centriole remaining in...

  5. Polo-like kinase 4 controls centriole duplication but does not directly regulate cytokinesis

    Holland, A. J.; Fachinetti, D.; Da Cruz, S.; Zhu, Q.; Vitre, B.; Lince-Faria, M.; Chen, D.; Parish, N.; Verma, I. M.; Bettencourt-Dias, M.; Cleveland, D. W.
    Centrioles organize the centrosome, and accurate control of their number is critical for the maintenance of genomic integrity. Centrioles duplicate once per cell cycle, and duplication is coordinated by Polo-like kinase 4 (Plk4). We previously demonstrated that Plk4 accumulation is autoregulated by its own kinase activity. However, loss of heterozygosity of Plk4 in mouse embryonic fibroblasts has been proposed to cause cytokinesis failure as a primary event, leading to centrosome amplification and gross chromosomal abnormalities. Using targeted gene disruption, we show that human epithelial cells with one inactivated Plk4 allele undergo neither cytokinesis failure nor increase in centrosome amplification. Plk4...

  6. Basal body structure and composition in the apicomplexans Toxoplasma and Plasmodium

    Francia, Maria E.; Dubremetz, Jean-Francois; Morrissette, Naomi S.
    The phylum Apicomplexa encompasses numerous important human and animal disease-causing parasites, including the Plasmodium species, and Toxoplasma gondii, causative agents of malaria and toxoplasmosis, respectively. Apicomplexans proliferate by asexual replication and can also undergo sexual recombination. Most life cycle stages of the parasite lack flagella; these structures only appear on male gametes. Although male gametes (microgametes) assemble a typical 9+2 axoneme, the structure of the templating basal body is poorly defined. Moreover, the relationship between asexual stage centrioles and microgamete basal bodies remains unclear. While asexual stages of Plasmodium lack defined centriole structures, the asexual stages of Toxoplasma and closely...

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