Centríolos contribuídos paternalmente persistem nos embriões de C. elegans: portadores de informação genética???

sexta-feira, abril 24, 2015

Cell Research advance online publication 24 April 2015; doi: 10.1038/cr.2015.49

Paternally contributed centrioles exhibit exceptional persistence in C. elegans embryos


Fernando R Balestra1, Lukas von Tobel1 and Pierre Gönczy1

1Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Switzerland

Correspondence: Pierre Gönczy, E-mail: pierre.gonczy@epfl.ch

Dear Editor:
The two gametes make different contributions to the zygote at fertilization. Although both gametes contribute genetic material, in most animal species the oocyte donates the bulk of cytoplasmic constituents and cellular organelles, including mitochondria, whereas the sperm donates two centrioles. Centrioles are microtubule-based organelles that serve as templates for the axoneme of cilia and flagella across eukaryotic evolution, and as platforms for centrosome assembly in most animal cells1. How long the two centrioles contributed by the sperm persist in the developing embryo is not known in any system. More generally, although centrioles are reputed to be stable structures, the extent to which their constituents persist over several cell cycles has been scarcely studied. Two instances of centriolar components being stable for one (α/β tubulin in mammalian cells) or two (SAS-4 in C. elegans) cell cycles have been reported2,3,4, but whether these and other centriolar components remain stable for more cell cycles is not known.
We used C. elegans as a model system to assess the persistence of centriolar components in the context of a developing organism. We utilized a marked mating experimental strategy to specifically mark paternally contributed centriolar components and assess their persistence throughout embryonic development (Figure 1Aand Supplementary information, Data S1). In brief, feminized fog-2 (q71) mutant worms lacking sperm were mated with males expressing a given centriolar protein fused to GFP, and the resulting embryos were analyzed using immunofluorescence with antibodies against GFP and the pan-centriolar marker IFA. Five evolutionarily conserved proteins (SPD-2, ZYG-1, SAS-4, SAS-5 and SAS-6) are specifically required for centriole formation in C. elegans1, a process that also requires the centriolar constituents α/β-tubulin5,6. For our analysis, we selected SAS-4, which has been reported to persist for two cell cycles in C. elegans3,4, as well as the β-tubulin protein TBB-2, since centriolar α/β tubulin has been shown to persist for one cell cycle in mammalian cells2. Moreover, we analyzed the behavior of SAS-6, the founding member of a protein family critical for the onset of centriole assembly across eukaryotic evolution7,8.
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