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Biology subjects

Tuna, Y.

Publications and source records attributed to Tuna, Y..

2 recordsLinked to original sources

A correlative quantitative phase contrast and fluorescence super-resolution microscope for imaging molecules in their cellular context

Fluorescence microscopy has been widely used to reveal the spatial distribution of specifically labeled molecules, but it is blind to cellular context. Quantitative phase contrast microscopy (QPC) provides such complementary information. Here we have developed a platform that combines the QPC technique of correlative orientation-independent differential interference contrast (OI-DIC) microscopy with single-molecule super-resolution fluorescence microscopy. We demonstrate a detection sensitivity of 0.05 nm optical path difference, sufficient to detect single microtubules, and show its capability of 3D super-resolution fluorescence imaging in the cellular context. Additionally, we report deep-learning enabled digital staining, identifying nuclei, mitochondria and lipid droplets from OI-DIC data and demonstrate the potential of this approach for long-term live-cell imaging of organelles of interest without the need for fluorescence. OI-DIC can be easily integrated into most fluorescence microscopes and is readily adoptable by microscopy labs. ONE-SENTENCE TEASERA highly sensitive technique to visualize sub-cellular structures, dynamics, and molecules in their cellular context.

cell biology↗

The force required to remove tubulin from the microtubule lattice

Severing enzymes and molecular motors extract tubulin from the walls of microtubules by exerting mechanical force on subunits buried in the lattice. However, how much force is needed to remove tubulin from microtubules is unknown, as is the pathway by which subunits are removed. Using a site-specific functionalization method, we applied forces to the C-terminus of -tubulin with an optical tweezer and found that a force of [~]30 pN is required to extract tubulin from the microtubule wall. Consistent with this force, we show that several kinesins can also extract tubulin. Additionally, we discovered that partial unfolding is an intermediate step in tubulin removal. The unfolding and extraction forces are similar to those generated by AAA-unfoldases, suggesting that severing proteins such as spastin and katanin use an unfoldase mechanism. Our results reveal the response of tubulin to mechanical force and advance our understanding of severing enzymes and microtubule stability.

biophysics↗