Genetic Basis of Metabolome Variation in Yeast

Metabolism, the conversion of nutrients into usable energy and biochemical building blocks, is an essential feature of all cells. The genetic factors responsible for inter-individual metabolic variability remain poorly understood. To investigate genetic causes of metabolome variation, we measured the concentrations of 74 metabolites across 100 segregants from a Saccharomyces cerevisiae cross by liquid chromatography-tandem mass spectrometry. We found 52 quantitative trait loci for 34 metabolites. These included linkages due to overt changes in metabolic genes, e.g., linking pyrimidine intermediates to the deletion of ura3. They also included linkages not directly related to metabolic enzymes, such as those for five central carbon metabolites to ira2, a Ras/PKA pathway regulator, and for the metabolites, S-adenosyl-methionine and S-adenosyl-homocysteine to slt2, a MAP kinase involved in cell wall integrity. The variant of ira2 that elevates metabolite levels also increases glucose uptake and ethanol secretion. These results highlight specific examples of genetic variability, including in genes without prior known metabolic regulatory function, that impact yeast metabolism.     

Modeling plasticity and dysplasia of pancreatic ductal organoids derived from human pluripotent stem cells

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CRISPR-Mediated Induction of Neuron-Enriched Mitochondrial Proteins Boosts Direct Glia-to-Neuron Conversion

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Multiphoton imaging of freezing and heating effects in plant leaves

Thermally‐induced changes in Arabidopsis thaliana leaves were investigated with a novel cryo microscope by multiphoton, fluorescence lifetime and spectral imaging as well as micro spectroscopy. Samples were excited with fs pulses in the near‐infrared range and cooled/heated in a cryogenic chamber. The results show morphological changes in the chloroplast distribution as well as a shift from chlorophyll to cell‐wall fluorescence with decreasing temperature. At temperatures below –40 °C, also second harmonic generation was observed. The measurements illustrate the suitability of multiphoton imaging to investigate thermally‐induced changes at temperatures used for cryopreservation as well as for basic investigations of thermal effects on plant tissue in general (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)