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Matrix-assisted laser desorption/ionisation mass spectrometry imaging and its development for plant protein imaging.

Grassl J, Taylor NL, Millar AH - Plant Methods (2011)

Bottom Line: The history of this technique in animals and plants is considered and the potential for analysis of proteins by this technique in plants is discussed.Protein biomarker identification from MALDI-MSI is a challenge and a number of different approaches to address this bottleneck are discussed.The technical considerations needed for MALDI-MSI are reviewed and these are presented alongside examples from our own work and a protocol for MALDI-MSI of proteins in plant samples.

View Article: PubMed Central - HTML - PubMed

Affiliation: ARC Centre of Excellence in Plant Energy Biology and Centre for Comparative Analysis of Biomolecular Networks, M316, The University of Western Australia, Crawley, WA 6009, Australia. harvey.millar@uwa.edu.au.

ABSTRACT
Matrix-Assisted Laser Desorption/Ionisation (MALDI) mass spectrometry imaging (MSI) uses the power of high mass resolution time of flight (ToF) mass spectrometry coupled to the raster of lasers shots across the cut surface of tissues to provide new insights into the spatial distribution of biomolecules within biological tissues. The history of this technique in animals and plants is considered and the potential for analysis of proteins by this technique in plants is discussed. Protein biomarker identification from MALDI-MSI is a challenge and a number of different approaches to address this bottleneck are discussed. The technical considerations needed for MALDI-MSI are reviewed and these are presented alongside examples from our own work and a protocol for MALDI-MSI of proteins in plant samples.

No MeSH data available.


MALDI-imaging in soybean cotyledons. (A) MALDI-MSI cross section of a soybean cotyledon. The localisation of 4 distinct m/z values is shown. (B) The individual peaks are overlayed in the same MALDI-MSI section. (C) The average mass spectrum of the cross section is shown highlighting the m/z values of interest.
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Figure 4: MALDI-imaging in soybean cotyledons. (A) MALDI-MSI cross section of a soybean cotyledon. The localisation of 4 distinct m/z values is shown. (B) The individual peaks are overlayed in the same MALDI-MSI section. (C) The average mass spectrum of the cross section is shown highlighting the m/z values of interest.

Mentions: Once the data acquisition is complete, individual spectra across the tissue section are aligned and compiled into an imaging map. Using some software packages, spectra processing such as baseline subtraction and smoothing is performed during the data acquisition process. For data acquisition, a range of imaging software packages are available. Some are open-source such as BioMap available from Novartis http://www.maldi-msi.org and ImageJ developed for the NIH http://rsbweb.nih.gov/ij; whereas others are vendor specific and tailored to the instrument and data format produced. In general the software packages are designed to overlay the optical image with the mass spectra acquired. Furthermore software available enables post processing for data analysis. More information on the wide range of software solutions is available from http://www.maldi-msi.org. MALDI-MSI produces very large data sets when obtained at high spatial resolution data. Powerful computer processors and large rapid access memory capacity are therefore required to process these data. Using hierarchical clustering (HC) and principal component analysis (PCA) images can be reconstructed, highlighting peaks as well as regions in the tissue that distinguish sample groups [51,64]. For review of the statistical methods used in MALDI-MSI a comprehensive tutorial is available [65]. The use of serial sections and 3D volume constructions can allow the in silico reconstruction of the organ analysed [65]. The layering of data showing the distribution of specific molecules of ions can be used to reconstruct images highlighting spatial features of tissue samples, as shown for soybean cotyledons from our own work in Figure 4.


Matrix-assisted laser desorption/ionisation mass spectrometry imaging and its development for plant protein imaging.

Grassl J, Taylor NL, Millar AH - Plant Methods (2011)

MALDI-imaging in soybean cotyledons. (A) MALDI-MSI cross section of a soybean cotyledon. The localisation of 4 distinct m/z values is shown. (B) The individual peaks are overlayed in the same MALDI-MSI section. (C) The average mass spectrum of the cross section is shown highlighting the m/z values of interest.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3141805&req=5

Figure 4: MALDI-imaging in soybean cotyledons. (A) MALDI-MSI cross section of a soybean cotyledon. The localisation of 4 distinct m/z values is shown. (B) The individual peaks are overlayed in the same MALDI-MSI section. (C) The average mass spectrum of the cross section is shown highlighting the m/z values of interest.
Mentions: Once the data acquisition is complete, individual spectra across the tissue section are aligned and compiled into an imaging map. Using some software packages, spectra processing such as baseline subtraction and smoothing is performed during the data acquisition process. For data acquisition, a range of imaging software packages are available. Some are open-source such as BioMap available from Novartis http://www.maldi-msi.org and ImageJ developed for the NIH http://rsbweb.nih.gov/ij; whereas others are vendor specific and tailored to the instrument and data format produced. In general the software packages are designed to overlay the optical image with the mass spectra acquired. Furthermore software available enables post processing for data analysis. More information on the wide range of software solutions is available from http://www.maldi-msi.org. MALDI-MSI produces very large data sets when obtained at high spatial resolution data. Powerful computer processors and large rapid access memory capacity are therefore required to process these data. Using hierarchical clustering (HC) and principal component analysis (PCA) images can be reconstructed, highlighting peaks as well as regions in the tissue that distinguish sample groups [51,64]. For review of the statistical methods used in MALDI-MSI a comprehensive tutorial is available [65]. The use of serial sections and 3D volume constructions can allow the in silico reconstruction of the organ analysed [65]. The layering of data showing the distribution of specific molecules of ions can be used to reconstruct images highlighting spatial features of tissue samples, as shown for soybean cotyledons from our own work in Figure 4.

Bottom Line: The history of this technique in animals and plants is considered and the potential for analysis of proteins by this technique in plants is discussed.Protein biomarker identification from MALDI-MSI is a challenge and a number of different approaches to address this bottleneck are discussed.The technical considerations needed for MALDI-MSI are reviewed and these are presented alongside examples from our own work and a protocol for MALDI-MSI of proteins in plant samples.

View Article: PubMed Central - HTML - PubMed

Affiliation: ARC Centre of Excellence in Plant Energy Biology and Centre for Comparative Analysis of Biomolecular Networks, M316, The University of Western Australia, Crawley, WA 6009, Australia. harvey.millar@uwa.edu.au.

ABSTRACT
Matrix-Assisted Laser Desorption/Ionisation (MALDI) mass spectrometry imaging (MSI) uses the power of high mass resolution time of flight (ToF) mass spectrometry coupled to the raster of lasers shots across the cut surface of tissues to provide new insights into the spatial distribution of biomolecules within biological tissues. The history of this technique in animals and plants is considered and the potential for analysis of proteins by this technique in plants is discussed. Protein biomarker identification from MALDI-MSI is a challenge and a number of different approaches to address this bottleneck are discussed. The technical considerations needed for MALDI-MSI are reviewed and these are presented alongside examples from our own work and a protocol for MALDI-MSI of proteins in plant samples.

No MeSH data available.