A Versatile Platform for Mass Spectrometry Imaging of Arbitrary Spatial Patterns

Garrard, Kenneth P.; Ekelöf, Måns; Khodjaniyazova, Sitora; Bagley, M. Caleb; Muddiman, David C.

doi:10.1021/jasms.0c00128

Cited by 21 publications

(29 citation statements)

References 10 publications

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“…The RF-level applied to the Slens ion guide was fixed at 70% for all analyses. RastirX software paired with an Arduino microcontroller (Arduino, Ivrea, Italy) was used to coordinate electronic signals required for each analysis (107). For each IR-MALDESI-MS analysis, 1 µL of sample was pipetted onto a glass microscope slide and placed on the sample stage with the focal point of the laser focused at the top of the sample droplet.…”

Section: Infrared Matrix-assisted Laser Desorption Electrospray Ioniz...mentioning

confidence: 99%

An adaptive teosintemexicanaintrogression modulates phosphatidylcholine levels and is associated with maize flowering time

Rodríguez-Zapata

Barnes

Blöcher-Juárez³

et al. 2021

Preprint

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After domestication from lowland teosinte parviglumis (Zea mays ssp. parviglumis) in the warm Mexican southwest, maize (Zea mays ssp. mays) colonized the highlands of Mexico and South America. In the highlands, maize was exposed to lower temperatures that imposed strong selection on flowering time. Phospholipids are important metabolites in plant responses to low-temperature, low phosphorus availability and have also been suggested to influence flowering time. Here, we combined linkage mapping analysis with genome scans to identify High PhosphatidylCholine 1 (HPC1), a gene which encodes a phospholipase A1 enzyme, as a major driver of phospholipid variation in highland maize. Common garden experiments demonstrated strong genotype-by-environment interactions associated with variation at HPC1, with the highland HPC1 allele leading to higher fitness in highlands, possibly by hastening flowering. The HPC1 variant we identified in highland maize results in impaired function of the encoded protein due to a polymorphism in a highly conserved sequence. A meta-analysis indicated a strong association between the identity of the amino acid at this position and optimal growth in prokaryotes. Mutagenesis of HPC1 via genome editing validated its role in regulating phospholipid metabolism. Finally, we show that the highland HPC1 allele entered cultivated maize by introgression from the wild highland teosinte Zea mays ssp. mexicana and has been maintained in maize breeding lines from Northern US, Canada and Europe. Thus, HPC1 introgressed from teosinte mexicana underlies a large metabolic QTL that modulates phosphatidylcholine levels and has an adaptive effect at least in part via induction of early flowering time.

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Section: Infrared Matrix-assisted Laser Desorption Electrospray Ioniz...mentioning

confidence: 99%

An adaptive teosintemexicanaintrogression modulates phosphatidylcholine levels and is associated with maize flowering time

Rodríguez-Zapata

Barnes

Blöcher-Juárez³

et al. 2021

Preprint

Self Cite

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“…The IR‐MALDESI source is currently coupled to an Orbitrap Exploris 240 mass spectrometer (Exploris 240, Thermo Fisher Scientific, Bremen, Germany). Electronic triggering of the Exploris 240, JGMA laser, and sample stage position were all controlled using RastirX, an in‐house software paired with an Arduino microcontroller 22,29 . A single burst of nine pulses (1.2 mJ/burst) from the JGMA 2970‐nm laser (Burlington, MA, USA) focused on the meniscus of the sample, which desorbed neutrals from the sample well plate.…”

Section: Methodsmentioning

confidence: 99%

“…Electronic triggering of the Exploris 240, JGMA laser, and sample stage position were all controlled using RastirX, an in-house software paired with an Arduino microcontroller. 22,29 A single burst of nine pulses (1.2 mJ/burst) from the JGMA…”

Section: Ir-maldesi-ms Platformmentioning

confidence: 99%

Normalization techniques for high‐throughput screening by infrared matrix‐assisted laser desorption electrospray ionization mass spectrometry

Knizner

Bagley

et al. 2022

J Mass Spectrom

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Mass spectrometry (MS) is an effective analytical tool for high‐throughput screening (HTS) in the drug discovery field. Infrared matrix‐assisted laser desorption electrospray ionization (IR‐MALDESI) MS is a high‐throughput platform that has achieved analysis times of sub‐seconds‐per‐sample. Due to the high‐throughput analysis speed, methods are needed to increase the analyte signal while decreasing the variability in IR‐MALDESI‐MS analyses to improve data quality and reduce false‐positive hits. The Z‐factor is used as a statistic of assay quality that can be improved by reducing the variation of target ion abundances or increasing signal. Herein we report optimal solvent compositions for increasing measured analyte abundances with direct analysis by IR‐MALDESI‐MS. We also evaluate normalization strategies, such as adding a normalization standard that is similar or dissimilar in structure to the model target drug, to reduce the variability of measured analyte abundances with direct analyses by IR‐MALDESI‐MS in both positive and negative ionization modes.

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“…Using this setup, each rastir pixel was split into 3 × 3 spatially separated spiral pixels, and each spiral pixel represented an individual scan event that was defined in the Xcalibur software (Thermo Scientific). A spiral pattern tool has been added to RastirX, 33 an innovative imaging control platform developed in our lab. The spiral pattern is realized by permuting the normal row‐major order of scan locations for an ROI using a simple indexing scheme.…”

Section: Methodsmentioning

confidence: 99%

In situ detection of fatty acid C=C positional isomers by coupling on‐tissue mCPBA epoxidation with infrared matrix‐assisted laser desorption electrospray ionization mass spectrometry

Garrard

Said

et al. 2021

Rapid Comm Mass Spectrometry

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Rationale Unsaturated fatty acids (UFAs) play vital roles in regulating cellular functions. In‐depth structural characterization of UFAs such as localizing carbon–carbon double bonds is fundamentally important but poses considerable challenges in mass spectrometry (MS) given that the most widely accessible ion activation method, low‐energy collision‐induced dissociation (CID), primarily generates uninformative fragments (e.g., neutral loss of CO2) that are not suggestive of the double‐bond positions. Methods m‐Chloroperoxybenzoic acid (mCPBA) was uniformly deposited onto the sample slides using a TM Sprayer, converting the carbon–carbon double bonds into epoxides under ambient conditions. The epoxidation product was ionized in situ by infrared matrix‐assisted laser desorption electrospray ionization mass spectrometry (IR‐MALDESI‐MS), and subsequently cleaved via CID, generating a diagnostic ion pair associated with the double‐bond position. The reaction efficiency, sensitivity and relative quantification capability of the method were validated with five UFA standards dried on glass slides, and then this strategy was demonstrated on thin tissue sections of rat liver and human bladder. Results The mCPBA reaction yielded conversion rates in the range of 44–60% in 10 min with high specificity and sensitivity. Further tandem mass spectrometry (MS/MS) of the mono‐epoxidized products generated informative fragment ions specific to the double‐bond positions, and relative quantification of positional isomers in binary mixtures was performed across a wide mole fraction from 0 to 1. An innovative spiral scan pattern was utilized during data acquisition, elucidating the major isomeric compositions of multiple UFAs from a tissue section in a single run. Conclusions The on‐tissue mCPBA epoxidation was implemented into an ambient MS imaging workflow to offer a rapid and simple way for in situ identification and relative quantification of double‐bond positional isomers without the requirement for instrument modification. The method can be readily implemented on many other MS platforms to reveal the role of double‐bond positional isomers in lipid biology and to discover potential biomarkers.

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A Versatile Platform for Mass Spectrometry Imaging of Arbitrary Spatial Patterns

Cited by 21 publications

References 10 publications

An adaptive teosintemexicanaintrogression modulates phosphatidylcholine levels and is associated with maize flowering time

An adaptive teosintemexicanaintrogression modulates phosphatidylcholine levels and is associated with maize flowering time

Normalization techniques for high‐throughput screening by infrared matrix‐assisted laser desorption electrospray ionization mass spectrometry

In situ detection of fatty acid C=C positional isomers by coupling on‐tissue mCPBA epoxidation with infrared matrix‐assisted laser desorption electrospray ionization mass spectrometry

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