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Summary: Polycomb repressive complex 1 (PRC1) undergoes phase separation to form Polycomb condensates that are multi-component hubs for silencing Polycomb target genes. In this study, we demonstrate that formation and regulation of PRC1 condensates are consistent with the scaffold-client model, where the Chromobox 2 (CBX2) protein behaves as the scaffold while the other PRC1 proteins are clients. Such clients induce a re-entrant phase transition of CBX2 condensates. The composition of the multi-component PRC1 condensates (1) determines the dynamic properties of the scaffold protein; (2) selectively promotes the formation of CBX4-PRC1 condensates while dissolving condensates of CBX6-, CBX7-, and CBX8-PRC1; and (3) controls the enrichment of CBX4-, CBX7-, and CBX8-PRC1 in CBX2-PRC1 condensates and the exclusion of CBX6-PRC1 from CBX2-PRC1 condensates. Our findings uncover how multi-component PRC1 condensates are assembled via an intricate scaffold-client mechanism whereby the properties of the PRC1 condensates are sensitively regulated by its composition and stoichiometry.

Providing clean water for energy generation is of particular importance. Due to limited water resources, hydropower generation is facing problems in today’s world societies. Due to this issue, the purpose of this study is to investigate the optimal management of water resources and its impact on optimal hydropower generation. The innovation of this research is the use of a new version of Developed Wildebeest Herd Optimization (DWHO) to forecast hydropower generation. This proposed algorithm solves optimization problems and increases the accuracy of the results obtained for reservoir operation to generate power. The results of this study showed that the developed algorithm has the highest convergence speed and utilizes minimum time-consuming mathematical processes to reach the global solution and prevents trapping in local solutions. The results related to the estimation of power showed that the DWHO method produces about 17% more electricity than other compared algorithms. Also, the highest reliability index 89.7% and resilience index 68.1% and the lowest vulnerability index 12.8% belong to the DWHO method.

Summary: This protocol provides instructions to track the global dynamics of single epigenetic regulatory factors in live cells. We describe an approach to generate cell lines that stably express HaloTag-fused proteins. We then use live-cell single-molecule tracking to obtain kinetic populations and residence times. The kinetic parameters obtained can be used to determine important aspects of transcriptional regulation such as target-search time, 3D free diffusion time, and number of non-specific sites sampled before reaching a specific site and compare behaviors across different nuclear environments.For complete details on the use and execution of this protocol, please refer to Kent et al. (2020).

Summary: Phase separation can produce local structures with specific functionality in the cell, and in the nucleus, this can lead to chromatin reorganization. Microrchidia 3 (MORC3) is a human ATPase that has been implicated in autoimmune disorders and cancer. Here, we show that MORC3 forms phase-separated condensates with liquid-like properties in the cell nucleus. Fluorescence live-cell imaging reveals that the MORC3 condensates are heterogeneous and undergo dynamic morphological changes during the cell cycle. The ATPase activity of MORC3 drives its phase separation in vitro and requires DNA binding and releasing the MORC3 CW domain-dependent autoinhibition through association with histone H3. Our findings suggest a mechanism by which the ATPase function of MORC3 mediates MORC3 nuclear compartmentalization. : Biophysical Chemistry; Biological Sciences; Molecular Biology Subject Areas: Biophysical Chemistry, Biological Sciences, Molecular Biology