The material properties of cell nuclei and their components are essential for all cellular processes. In particular, the thickness or viscosity of the nucleoplasm affects how molecules and organelles move within the nucleus and scientists think that these properties are altered in various human diseases. However, measuring these properties has previously proved difficult as the methods used have been hindered by the way cells respond to them.
Now, Zidovska and colleagues have overcome this limitation by using the dynamics and events that occur naturally within the cell nucleus to determine the properties of the nucleus and its components. They used a technique called high resolution spinning disc confocal microscopy, which measures spatial and temporal behavior within live cells. The team’s noninvasive approach revealed aspects within cells that had not previously been known. In particular, human nucleoli behave like liquid droplets and the nucleoplasm surrounding the droplets is of extremely high viscosity – a feature that slows down the coalescence of the droplets in healthy cells.
She adds that in many diseases such as Parkinson’s, Alzheimer’s and cancer, the size and shape of the nucleus changes and by understanding what drives these changes such as potential variations in the viscosity of nucleolar droplets, researchers could improve their understanding of the nucleolus and nucleus in states of both health and disease.