Methods in molecular biology
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Human pluripotent stem cells (PSCs), which include human embryonic stem cells (ESCs) as well as induced pluripotent stem cells (iPSCs), represent an important source of cellular therapies in regenerative medicine and the study of early human development. As such, it is becoming increasingly important to develop methods for the large-scale banking of human PSC lines. There are several well-established methods for the propagation of human PSCs. ⋯ Nevertheless, as the field develops, it will no doubt become increasingly important to produce a bank of cells for clinical use without xenogeneic reagents, particularly nonhuman feeder cells which might harbor viruses with potential risk to human health or cell product integrity. Thus, even for cell lines previously exposed to xenogeneic reagents, it is important to minimize any subsequent exposure of the cell lines to additional adventitious agents. We have specifically described procedures for the growth of hESCs on Matrigel, an animal-matrix, and CELLstart, an animal-free matrix, and these can be used to produce hESCs as part of a clinical manufacturing process.
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Since the first fungal genome was sequenced in 1996, sequencing technologies have advanced dramatically. In recent years, it has become possible to cost-effectively generate vast amounts of DNA sequence data using a number of cell- and electrophoresis-free sequencing technologies, commonly known as "next" or "second" generation. In this chapter, we present a brief overview of next-generation sequencers that are commercially available now. Their potential applications in fungal genomics studies are discussed.
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The posttranslational modification of proteins is important for the regulation of enzymatic activity, protein half-life, and interaction with other molecules. One of the best understood posttranslational modifications is the reversible phosphorylation of proteins at serine, threonine, or tyrosine residues. ⋯ Furthermore, phosphoproteome analyses are incompatible with long organelle isolation procedures prior to analysis, because of the highly dynamic nature of regulatory phosphorylations. In this chapter, we provide a detailed step-by-step overview of the complex experimental setup required for successful chloroplast phosphoproteome analysis, report our experience with existing methods, and comment on their application in the field.
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Understanding the signaling pathways governing pluripotency and self-renewal is a prerequisite for better controlling stem cell differentiation to specific fates. Reversible protein phosphorylation is one of the most important posttranslational modifications regulating signaling pathways in biological processes. Global analysis of dynamic changes in protein phosphorylation is, therefore, key to understanding signaling at the system level. ⋯ Our method combines the use of strong cation exchange (SCX) and titanium dioxide (TiO(2)) for phosphopeptide enrichment, high-resolution MS for peptide and protein identification, and stable isotope labeling by amino acids in cell culture (SILAC) for quantification. This approach allows us to identify thousands of phosphorylation sites and profile their relative abundance during differentiation. This systems-biology-based approach provides new insights into how human pluripotent stem cells exit the pluripotent state.
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Human embryonic stem cells (hESCs) are pluripotent cells derived from the embryo at the blastocyst stage. Their embryonic origin confers upon them the capacity to proliferate indefinitely in vitro while maintaining the capacity to differentiate into a large variety of cell types. ⋯ Consequently, the possibility to expand hESCs in serum-free and in feeder-free culture conditions is becoming a major challenge to deliver the clinical promises of hESCs. Here, we describe the basic principles of growing hESCs in a chemically defined medium (CDM) devoid of serum and feeders.