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Biology subjects

Kumar, J.

Publications and source records attributed to Kumar, J..

2 recordsLinked to original sources

The Cell Cycle Browser: an interactive tool for visualizing, simulating, and perturbing cell cycle progression

SUMMARYThe cell cycle is driven by precise temporal coordination among many molecular activities. To understand and explore this process, we developed the Cell Cycle Browser (CCB), an interactive web interface based on real-time reporter data collected in proliferating human cells. This tool facilitates visualizing, simulating, and predicting the outcomes of perturbing cell cycle parameters. Time-series traces from individual cells can be combined to build a multi-layered timeline of molecular activities. Users can simulate the cell cycle using computational models that capture the dynamics of molecular activities and phase transitions. By adjusting individual expression levels and strengths of molecular relationships, users can predict effects on the cell cycle. Virtual assays, such as growth curves and flow cytometry, provide familiar outputs to compare cell cycle behaviors for data and simulations. The CCB serves to unify our understanding of cell cycle dynamics and provides a platform for generating hypotheses through virtual experiments.\n\nHIGHLIGHTSO_LIUsers can stack and align single-cell traces for different molecular reporters\nC_LIO_LIComputational models with adjustable parameters simulate cell cycle progression\nC_LIO_LIVirtual growth curves and flow cytometry assays predict cell cycle behaviors\nC_LI

systems biology

Pif1-family helicases cooperate to suppress widespread replication fork arrest at tRNA genes

Saccharomyces cerevisiae encodes two distinct Pif1-family helicases - Pif1 and Rrm3 - which have been reported to play distinct roles in numerous nuclear processes. Here, we systematically characterize the roles of Pif1 helicases in replisome progression and lagging-strand synthesis in S. cerevisiae. We demonstrate that either Pif1 or Rrm3 redundantly stimulate strand-displacement by DNA polymerase {delta} during lagging-strand synthesis. By analyzing replisome mobility in pif1 and rrm3 mutants, we show that Rrm3, with a partially redundant contribution from Pif1, suppresses widespread terminal arrest of the replisome at tRNA genes. Although both head-on and codirectional collisions induce replication fork arrest at tRNA genes, head-on collisions arrest a higher proportion of replisomes; consistent with this observation, we find that head-on collisions between tRNA transcription and replisome progression are under-represented in the S. cerevisiae genome. Further, we demonstrate that tRNA-mediated arrest is R-loop independent, and propose that replisome arrest and DNA damage are mechanistically separable.

molecular biology