Microtubule nucleation is highly regulated during the eukaryotic cell cycle, but the underlying molecular mechanisms are largely unknown. During mitosis in fission yeast Schizosaccharomyces pombe, cytoplasmic microtubule nucleation ceases simultaneously with intranuclear mitotic spindle assembly. Cytoplasmic nucleation depends on the Mto1/2 complex, which binds and activates the γ-tubulin compl...

In this contribution, we review the recent literature on an alternative crystallization pathway involving stable clusters prior to nucleation and show that the prenucleation cluster pathway is a truly non-classical concept of nucleation. Prenucleation clusters are solutes with "molecular" character in aqueous solution. It becomes evident that the stable clusters may have been concealed by the s...

Actin nucleation by the Arp2/3 complex is under tight control, remaining inactive until stimulation by nucleation-promoting factors (NPFs). Although multiple NPFs are expressed in most cell types, little is known about how they are coordinated and whether they perform similar or distinct functions. We examined genetic relationships among the four S. cerevisiae NPFs. Combining las17delta with pa...

Prediction of the nucleation mechanism is one of the most critical factors in the design of a crystallization system. Information about the nucleation mechanism helps to control the size, shape, size distribution, and purity of the produced crystals. When the crystallization method is used for producing nanoparticles, the nucleation mechanism should be predicted. In this study, an empirical cor...

Nature has evolved many elegant solutions to enable life to flourish at low temperatures by either allowing (tolerance) or preventing (avoidance) ice formation. These processes are typically controlled by ice nucleating proteins or antifreeze proteins, which act to either promote nucleation, prevent nucleation or inhibit ice growth depending on the specific need, respectively. These proteins ca...

Neurons have highly polarized arrangements of microtubules, but it is incompletely understood how microtubule polarity is controlled in either axons or dendrites. To explore whether microtubule nucleation by γ-tubulin might contribute to polarity, we analyzed neuronal microtubules in Drosophila containing gain- or loss-of-function alleles of γ-tubulin. Both increased and decreased activity of γ...

We have studied the regulation of microtubule nucleating activity of the centrosome using cell-free extracts from Xenopus eggs. We found that the number of microtubules per centrosome increases dramatically with time during incubation of isolated centrosomes in interphasic egg extracts prepared 20-30 minutes after electric activation of cytostatic factor (CSF)-arrested eggs. The increase in mic...