Altered glycolysis is a hallmark of diseases including diabetes and cancer. Despite intensive study of the contributions of individual glycolytic enzymes, systems-level analyses of flux control through glycolysis remain limited. Here, we overexpress in two mammalian cell lines the individual enzymes catalyzing each of the 12 steps linking extracellular glucose to excreted lactate, and find substantial flux control at four steps: glucose import, hexokinase, phosphofructokinase, and lactate export (and not at any steps of lower glycolysis). The four flux-controlling steps are specifically upregulated by the Ras oncogene: optogenetic Ras activation rapidly induces the transcription of isozymes catalyzing these four steps and enhances glycolysis. At least one isozyme catalyzing each of these four steps is consistently elevated in human tumors. Thus, in the studied contexts, flux control in glycolysis is concentrated in four key enzymatic steps. Upregulation of these steps in tumors likely underlies the Warburg effect.

Ascidian embryos highlight the importance of cell lineages in animal development. As simple proto-vertebrates they also provide insights into the evolutionary origins of novel cell types, such as cranial placodes and neural crest. To build upon these efforts we have determined single cell transcriptomes for more than 90,000 cells spanning the entirety of Ciona intestinalis development, from the onset of gastrulation to swimming tadpoles. This represents an average of over 12-fold coverage for every cell at every stage of development, owing to the small cell numbers of ascidian embryos. Single cell transcriptome trajectories were used to construct "virtual" cell lineage maps and provisional gene networks for nearly 40 different neuronal subtypes comprising the larval nervous system. We summarize several applications of these datasets, including annotating the synaptome of swimming tadpoles and tracing the evolutionary origin of novel cell types such as the vertebrate telencephalon. Single cell RNA sequencing (scRNA-seq) methods are revolutionizing our understanding of how cells are specified to become definitive tissues during development 1-5. These studies Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

Stable isotope labeling techniques have been widely applied in the field of metabolomics and proteomics.Before the measured mass spectrum data can be used for quantitative analysis, it must be accurately corrected for isotope natural abundance and tracer isotopic impurity. Despite the increasing popularity of dual-isotope tracing strategy such as 13 C-15 N or 13 C-2 H, there is no accurate tool for correcting isotope natural abundance for such experiments. Here, we present AccuCor2 as an R-based tool to perform the correction for 13 C-15 N or 13 C-2 H labeling experiments. Our results show that the dual-isotope experiments often require a mass resolution that is high enough to resolve 13 C and 15 N or 13 C and 2 H.Otherwise the labeling pattern is not solvable. However, this mass resolution may not be sufficiently high to resolve other non-tracer elements such as oxygen or sulfur from the tracer elements. Therefore, we design AccuCor2 to perform the correction based on the actual mass resolution of the measurements. Using both simulated and experimental data, we show that AccuCor2 performs accurate and resolution dependent correction for dual-isotope tracer data. File list (3) download file view on ChemRxiv AccuCor2 Isotope Natural Abundance Correction for Dual-... (1.77 MiB) download file view on ChemRxiv Support Information.docx (18.43 KiB) download file view on ChemRxiv Support Information.docx (18.43 KiB)

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