Tournier, S. | bioRxiv Science

bioRxiv2020

Super-resolved live-cell imaging using Random Illumination Microscopy

Super-resolution fluorescence microscopy has been instrumental to progress in biology. Yet, the photo-induced toxicity, the loss of resolution into scattering samples or the complexity of the experimental setups curtail its general use for functional cell imaging. Here, we describe a new technology for tissue imaging reaching a 114nm/8Hz resolution at 30 {micro}m depth. Random Illumination Microscopy (RIM) consists in shining the sample with uncontrolled speckles and extracting a high-fidelity super-resolved image from the variance of the data using a reconstruction scheme accounting for the spatial correlation of the illuminations. Super-resolution unaffected by optical aberrations, undetectable phototoxicity, fast image acquisition rate and ease of use, altogether, make RIM ideally suited for functional live cell imaging in situ. RIM ability to image molecular and cellular processes in three dimensions and at high resolution is demonstrated in a wide range of biological situations such as the motion of Myosin II minifilaments in Drosophila.

bioengineering↗

bioRxiv2020

Aurora B and Condensin are dispensable for chromosome arm and telomere separation during meiosis II

In mitosis, while the importance of kinetochore-microtubule attachment has been known for many years, increasing evidence suggests that telomere dysfunctions also perturb chromosome segregation by contributing to the formation of chromatin bridges at anaphase. Recent evidence suggests that Aurora B ensures proper chromosome segregation during mitosis not only by controlling kinetochore-microtubule attachment but also by regulating telomere and chromosome arm separation. However, whether and how Aurora-B governs telomere separation during meiosis has remained unknown. Here, we show that fission yeast Aurora B localizes at telomeres during meiosis I and promotes telomere separation independently of the meiotic cohesin Rec8. In meiosis II, Aurora-B controls kinetochore-microtubule attachment but appears dispensable for telomere and chromosome arm separation. Likewise, condensin activity is nonessential in meiosis II for telomere and chromosome arm separation. Thus, in meiosis, the requirements for Aurora-B are distinct at centromeres and telomeres, illustrating the critical differences in the control of chromosome segregation between mitosis and meiosis II.

cell biology↗