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This review focuses on imaging DNA and single RNA molecules in living cells to define eukaryotic functional organization and dynamic processes. The latest advances in technologies to visualize individual DNA loci and RNAs in real time are discussed. Single-molecule fluorescence microscopy provides the spatial and temporal resolution to reveal mechanisms regulating fundamental cell functions. Novel insights into the regulation of nuclear architecture, transcription, posttranscriptional RNA processing, and RNA localization provided by multicolor fluorescence microscopy are reviewed. A perspective on the future use of live imaging technologies and overcoming their current limitations is provided. [ABSTRACT FROM AUTHOR]

RNA is the fundamental information transfer system in the cell. The ability to follow single messenger RNAs (mRNAs) from transcription to degradation with fluorescent probes gives quantitative information about how the information is transferred from DNA to proteins. This review focuses on the latest technological developments in the field of single-mRNA detection and their usage to study gene expression in both fixed and live cells. By describing the application of these imaging tools, we follow the journey of mRNA from transcription to decay in single cells, with single-molecule resolution. We review current theoretical models for describing transcription and translation that were generated by single-molecule and single-cell studies. These methods provide a basis to study how single-molecule interactions generate phenotypes, fundamentally changing our understating of gene expression regulation. [ABSTRACT FROM AUTHOR]

Recent advancements in single-cell and single-molecule imaging technologies have resolved biological processes in time and space that are fundamental to understanding the regulation of gene expression. Observations of single-molecule events in their cellular context have revealed highly dynamic aspects of transcriptional and post-transcriptional control in eukaryotic cells. This approach can relate transcription with mRNA abundance and lifetimes. Another key aspect of single-cell analysis is the cell-to-cell variability among populations of cells. Definition of heterogeneity has revealed stochastic processes, determined characteristics of under-represented cell types or transitional states, and integrated cellular behaviors in the context of multicellular organisms. In this review, we discuss novel aspects of gene expression of eukaryotic cells and multicellular organisms revealed by the latest advances in single-cell and single-molecule imaging technology. [ABSTRACT FROM AUTHOR]

The advent of new technologies for the imaging of living cells has made it possible to determine the properties of transcription, the kinetics of polymerase movement, the association of transcription factors, and the progression of the polymerase on the gene. We report here the current state of the field and the progress necessary to achieve a more complete understanding of the various steps in transcription. Our Consortium is dedicated to developing and implementing the technology to further this understanding. [ABSTRACT FROM AUTHOR]

The combined use of the new technologies of multiphoton-based intravital imaging, the chemotaxis-mediated collection of invasive cells, and high sensitivity expression profiling has allowed the correlation of the behavior of invasive tumor cells in vivo with their gene expression patterns. New insights have resulted including a gene expression signature for invasive cells and the tumor microenvironment invasion model. This model proposes that tumor invasion and metastasis can be studied as a problem resembling normal morphogenesis. We discuss how these new insights may lead to a better understanding of the molecular basis of the invasive behavior of tumor cells in vivo, which may result in new strategies for the diagnosis and treatment of metastasis. [ABSTRACT FROM AUTHOR]

The localization of mRNAs is used by various types of polarized cells to locally translate specific proteins, which restricts their distribution to a particular sub-region of the cytoplasm. This mechanism of protein sorting is involved in major biological processes such as asymmetric cell division, oogenesis, cellular motility, and synapse formation. With the finding of localized mRNAs in the yeast Saccharomyces cerevisiae, it is now possible to benefit from the powerful yeast laboratory tools to explore the molecular basis of RNA localization. Because mRNA transport and localization in yeast share many features with RNA localization in higher eukaryotes, including the formation of a large ribonucleoprotein (RNP) localization complex, the requirement of a polarized cytoskeleton and molecular motors, and the role of nuclear RNA-binding proteins in cytoplasmic localization, the yeast can be used as a paradigm for unraveling the molecular aspects of this process. This review summarizes the current knowledge on RNP transport and localization in yeast. [ABSTRACT FROM AUTHOR]