Metabolic Differentiation of Neuronal Phenotypes by Single-cell Capillary Electrophoresis-Electrospray Ionization-Mass Spectrometry

Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
Analytical Chemistry (Impact Factor: 5.64). 08/2011; 83(17):6810-7. DOI: 10.1021/ac2015855
Source: PubMed


Single-cell mass spectrometry (MS) is a rapidly emerging field in metabolic investigations. The inherent chemical complexity of most biological samples poses analytical challenges when using MS platforms to measure sample content without prior chemical separation. Here, a single-cell capillary electrophoresis (CE) system was coupled with electrospray ionization (ESI) MS to enable the simultaneous measurement of a vast array of endogenous compounds in over 50 identified and isolated large neurons from the Aplysia californica central nervous system. More than 300 distinct ion signals (m/z values) were detected from a single neuron in the positive ion mode, 140 of which were selected for chemometric data analysis. Metabolic features were evaluated among six different neuron types (B1, B2, left pleural 1 (LPl1), metacerebral cell (MCC), R2, and R15) chosen for their various physiological functions. The results indicated chemical similarities among some neuron types (B1 to B2 and LPl1 to R2) and distinctive features for others (MCC and R15 cells). The quantitative nature of the MS platform allowed the comparison of metabolite levels for specific neurons. The CE-ESI-MS approach for examination of individual nanoliter-volume cells as described herein is readily adaptable to other volume-limited samples.


Available from: Peter Nemes
  • Source
    • "Even with an efficient separation from a complex tissue extract, overlapping peaks can be expected. While mass spectrometry can be used as a detector for CE [40] [41] [42], its effectiveness for chiral separations requiring surfactant-based chiral selectors is limited. Hence, we used LIF detection to confirm the peak identities via enzymatic degradation, similar to what we used to quantify D-Asp and D-Ser [43] [44]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Relatively high levels of d-alanine (d-Ala), an endogenous d-amino acid, have been found in the endocrine systems of several animals, especially in the anterior pituitary; however, its functional importance remains largely unknown. We observed d-Ala in islets of Langerhans isolated from rat pancreas in significantly higher levels than in the anterior/intermediate pituitary; specifically, 180 ± 60 fmol d-Ala per islet (300 ± 100 nmol/g islet), and 10 ± 2.5 nmol/g of wet tissue in pituitary. Additionally, 12 ± 5% of the free Ala in the islets was in the d-isomer, almost an order of magnitude higher than the percentage of d-Ala found in the pituitary. Surprisingly, glucose stimulation of the islets resulted in d-Ala release of 0.6 ± 0.5 fmol per islet. As d-Ala is stored in islets and released in response to changes in extracellular glucose, d-Ala may have a hormonal role.
    Biochemical and Biophysical Research Communications 04/2014; 447(2). DOI:10.1016/j.bbrc.2014.03.153 · 2.30 Impact Factor
    • "In a study combining CE separation, MS identification, and chemometric quantification, we investigated cellular heterogeneity among physiologically well-characterized identified neurons of A. californica. Out of 300 detected species, 144 were structurally identified, and 50 quantified, revealing surprising differences not only between neuronal types but among individual neurons of the same type (Nemes et al., 2011). These observations contribute new evidence about the physiological differences in neuron phenotypes. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Modern science is characterized by integration and synergy between research fields. Accordingly, as technological advances allow new and more ambitious quests in scientific inquiry, numerous analytical and engineering techniques have become useful tools in biological research. The focus of this review is on cutting edge technologies that aid direct measurement of bioactive compounds in the nervous system to facilitate fundamental research, diagnostics, and drug discovery. We discuss challenges associated with measurement of cell to cell signaling molecules in the nervous system, and advocate for a decrease of sample volumes to the nanoliter volume regime for improved analysis outcomes. We highlight effective approaches for the collection, separation, and detection of such small-volume samples, present strategies for targeted and discovery-oriented research, and describe the required technology advances that will empower future translational science.Neuropsychopharmacology accepted article preview online, 10 June 2013; doi:10.1038/npp.2013.145.
    Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 06/2013; 39(1). DOI:10.1038/npp.2013.145 · 7.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This review provides an update of the state-of-the-art of CE-MS for metabolomic purposes, covering the scientific literature from July 2008 to June 2010. This review describes the different analytical aspects with respect to non-targeted and targeted metabolomics and the new technological developments used in CE-MS for metabolomics. The applicability of CE-MS in metabolomics research is illustrated by examples of the analysis of biomedical and clinical samples, and for bacterial and plant extracts. The relevant papers on CE-MS for metabolomics are comprehensively summarized in a table, including, e.g. information on sample type and pretreatment, and MS detection mode. Future considerations such as challenges for large-scale and (quantitative) clinical metabolomics studies and the use of sheathless interfacing and different ionization techniques are discussed.
    Electrophoresis 01/2011; 32(1):52-65. DOI:10.1002/elps.201000378 · 3.03 Impact Factor
Show more