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VIDEO ABSTRACT The pattern of blood flow has long been thought to play a significant role in vascular morphogenesis, yet the flow-sensing mechanism that is involved at early embryonic stages, when flow forces are low, remains unclear. It has been proposed that endothelial cells use primary cilia to sense flow, but this has never been tested in vivo. Here we(More)
Topoisomerase IV (Topo IV), an essential ATP-dependent bacterial type II topoisomerase, transports one segment of DNA through a transient double-strand break in a second segment of DNA. In vivo, Topo IV unlinks catenated chromosomes before cell division and relaxes positive supercoils generated during DNA replication. In vitro, Topo IV relaxes positive(More)
DNA encounters topological problems in vivo because of its extended double-helical structure. As a consequence, the semiconservative mechanism of DNA replication leads to the formation of DNA braids or catenanes, which have to be removed for the completion of cell division. To get a better understanding of these structures, we have studied the elastic(More)
The recent development of new techniques to manipulate single DNA molecules has opened new opportunities for the study of the enzymes that control DNA topology: the type I and II topoisomerases. These single-molecule assays provide a unique way to study the uncoiling of single supercoiled DNA molecules and the unlinking of two intertwined DNAs. They allow(More)
BACKGROUND Imaging single cells with fluorescent markers over multiple cell cycles is a powerful tool for unraveling the mechanism and dynamics of the cell cycle. Over the past ten years, microfluidic techniques in cell biology have emerged that allow for good control of growth environment. Yet the control and quantification of transient gene expression in(More)
Budding yeast cells irreversibly commit to a new division cycle at a regulatory transition called Start. This essential decision-making step involves the activation of the SBF/MBF transcription factors. SBF/MBF promote expression of the G1 cyclins encoded by CLN1 and CLN2. Cln1,2 can activate their own expression by inactivating the Whi5 repressor of(More)
In vertebrates, heart pumping is required for cardiac morphogenesis and altering myocardial contractility leads to abnormal intracardiac flow forces and valve defects. Among the different mechanical cues generated in the developing heart, oscillatory flow has been proposed to be an essential factor in instructing endocardial cell fate toward valvulogenesis(More)
During the past 10 years, major developments in live-cell imaging methods have accompanied growing interest in the application of microfluidic techniques to biological imaging. The broad design possibilities of microfabrication and its relative ease of implementation have led to the development of a number of powerful imaging assays. Specifically, there has(More)
Type-II topoisomerases are responsible for untangling DNA during replication by removing supercoiled and interlinked DNA structures. Using a single-molecule micromanipulation setup, we follow the real-time decatenation of two mechanically braided DNA molecules by Drosophila melanogaster topoisomerase (Topo) II and Escherichia coli Topo IV. Although Topo II(More)
Gene expression plays a central role in the orchestration of cellular processes. The use of inducible promoters to change the expression level of a gene from its physiological level has significantly contributed to the understanding of the functioning of regulatory networks. However, from a quantitative point of view, their use is limited to short-term,(More)