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Enikolopov G.,Cold Spring Harbor Laboratory | Guillermier C.,Brigham and Womens Hospital | Wang M.,National Resource for Imaging Mass Spectrometry NRIMS | Trakimas L.,Harvard University | And 2 more authors.
Surface and Interface Analysis | Year: 2014

New neurons are continuously produced from neural stem cells in specific regions of the adult brain of animals and humans. In the hippocampus, a region crucial for cognitive function, neurogenesis responds to a multitude of extrinsic stimuli; emerging evidence indicates that it may be important for behavior, pathophysiology, brain repair, and response to drugs. We have developed an approach to identify and quantify the cellular targets of pro- and anti-neurogenic stimuli, based on reporter transgenicmouse lines in which neural stemand progenitor cells or their progeny aremarked by fluorescent proteins. Here, we demonstrate the feasibility of using multi-isotope imaging mass spectrometry for studying adult neurogenesis. Copyright © 2014 John Wiley & Sons, Ltd.

Saiardi A.,University College London | Guillermier C.,Harvard University | Loss O.,University College London | Poczatek J.C.,National Resource for Imaging Mass Spectrometry NRIMS | Lechene C.,Harvard University
Surface and Interface Analysis | Year: 2014

Despite the widely recognized importance of the several species of inositol polyphosphates in cell biology, inositol has not been successfully imaged and quantified inside cells using traditional spectrophotometry. Multi-isotope imaging mass spectrometry (MIMS) technology, however, has facilitated direct imaging and measurement of cellular inositol. After pulsing cells with inositol labeled with the stable isotope Carbon-13 (13C), the label was detected in subcellular volumes by MIMS. The tridimensional localization of 13C within the cell illustrated cellular distribution and local accumulation of inositol. In parallel, we performed control experiments with 13C-glucose to compare a different 13C distribution pattern. Because many functions recently attributed to inositol polyphosphates are localized in the nucleus, we analyzed its relative nuclear concentration. We engineered yeast with human thymidine permease and viral thymidine kinase then fed them with 15N-thymidine. This permitted direct analysis of the nuclear DNA through the detection of the 15N isotopic signal. We found practically no co-localization between inositol signal (13C-isotope) and nuclear signal (15N-isotope). The 13C-tag (inositol) accumulation was highest at the plasma membrane and in cytoplasmic domains. In time-course labeling experiments performed with wild-type (WT) yeast or modified yeast unable to synthesize inositol from glucose (ino1Δ), the halftime of labeled inositol accumulation was ∼1 h in WT and longer in ino1Ä. These studies should serve as a template to study metabolism and physiological role of inositol using genetically modified yeasts. Copyright © 2014 John Wiley & Sons, Ltd.

Filiou M.D.,Max Planck Institute of Psychiatry | Moy J.,National Resource for Imaging Mass Spectrometry NRIMS | Wang M.,National Resource for Imaging Mass Spectrometry NRIMS | Guillermier C.,Harvard University | And 3 more authors.
Surface and Interface Analysis | Year: 2014

Although antidepressants have been used in the treatment of affective disorders for over 50 years, the precise mechanismof their action remains unknown. Treatment regimens are based by and large on empirical parameters and characterized by a trial and error scheme. A better understanding of themechanisms involved in antidepressant drug response is of fundamental importance for the development of new compounds that have a higher success rate and specificity. In order to elucidate the molecular pathways involved in the action of antidepressants, we wish to identify brain areas, cell types and organelles that are targeted by antidepressant treatment in mice. Multi-isotope imaging mass spectrometry allows a quantitative approach to this analysis, enabling us to delineate antidepressant effect on protein synthesis in the brain at single cell and organelle resolution. In these experiments, we obtained a global analysis of protein turnover in the hippocampus dentate gyrus and in the Cornu Ammonis regions, together with a subcellular analysis in the granular cells and others. Copyright © 2014 John Wiley & Sons, Ltd.

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