Mass spectrometry based metabolomics is a widely used approach in biomedical research. However, current methods coupling mass spectrometry with chromatography are timeconsuming and not suitable for high-throughput analysis of thousands of samples. An alternative approach is flow-injection mass spectrometry (FI-MS) in which samples are directly injected to the ionization source. Here, we show that the sensitivity of Orbitrap FI-MS metabolomics methods is limited by ion competition effect. We describe an approach for overcoming this effect by analyzing the distribution of ion m/z values and computationally determining a series of optimal scan ranges. This enables reproducible detection of~9,000 and~10,000 m/z features in metabolomics and lipidomics analysis of serum samples, respectively, with a sample scan time of~15 s and duty time of~30 s; a~50% increase versus current spectral-stitching FI-MS. This approach facilitates high-throughput metabolomics for a variety of applications, including biomarker discovery and functional genomics screens.
2-hydroxyglutarate (2HG) is recognized as an epigenetic regulator in cancer and in a few physiological states. Of all organs, the testis harbors the highest levels of 2HG, yet it's putative functions in germ cell biology are unknown. Here we show that 2HG is generated in specific stages of the mouse germ cell lineage by the testis specific lactate dehydrogenase C (LDHC). LDHC is expressed in pachytene, diplotene and diakinesis (PDD) cells and unexpectedly enters nuclei where it localizes along chromosomes and centromeres. LDHC-generated L-2HG controls centromere compaction and pericentromeric heterochromatin organization through multiple effects including clustering of chromocenters, centromere and chromocenter condensation and expression of satellite RNAs. The involvement of L-2HG in the above functions was shown both in isolated PDD cells and in vivo and is specific to the L but not D enantiomer. Our findings reveal that 2HG can rapidly change the conformation of these multisubunit structures and is necessary for the proper progression of the cell cycle.
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