Inferring mitochondrial and cytosolic metabolism by coupling isotope tracing and deconvolution.

The inability to inspect metabolic activities within distinct subcellular compartments has been a major barrier to our understanding of eukaryotic cell metabolism. Previous work addressed this challenge by analyzing metabolism in isolated organelles, which grossly bias metabolic activity. Here, we describe a method for inferring physiological metabolic fluxes and metabolite concentrations in mitochondria and cytosol based on isotope tracing experiments performed with intact cells.

Tumor Reliance on Cytosolic versus Mitochondrial One-Carbon Flux Depends on Folate Availability.

Folate metabolism supplies one-carbon (1C) units for biosynthesis and methylation and has long been a target for cancer chemotherapy. Mitochondrial serine catabolism is considered the sole contributor of folate-mediated 1C units in proliferating cancer cells. Here, we show that under physiological folate levels in the cell environment, cytosolic serine-hydroxymethyltransferase (SHMT1) is the predominant source of 1C units in a variety of cancers, while mitochondrial 1C flux is overly repressed.

Ice Scallops: A Laboratory Investigation of the Ice-Water Interface.

Ice scallops are a small-scale (5-20cm) quasi-periodic ripple pattern that occurs at the ice-water interface. Previous work has suggested that scallops form due to a self-reinforcing interaction between an evolving ice-surface geometry, an adjacent turbulent flow field, and the resulting differential melt rates that occur along the interface. In this study, we perform a series of laboratory experiments in a refrigerated flume to quantitatively investigate the mechanisms of scallop formation and evolution in high resolution.