| AVS 65th International Symposium & Exhibition | |
| Applied Surface Science Division | Monday Sessions |
| Session AS-MoA |
| Session: | Multitechnique Applications-When More techniques are Better than One |
| Presenter: | Tina Angerer, University of Washington |
| Authors: | T.B. Angerer, University of Washington D. Velickovic, Pacific Northwest National Laboratory C. Nicora, Pacific Northwest National Laboratory C.R. Anderton, Pacific Northwest National Laboratory D.J. Graham, University of Washington L.J. Gamble, University of Washington |
| Correspondent: | Click to Email |
Phagocata gracilis are planarian, non-parasitic flatworms. Planarians are best known for their fascinating regenerative abilities, requiring a complex interplay of a wide range of molecules. The regeneration process and the molecules involved are still poorly understood. Most notably there is a lack of lipid and fatty acid data, a diverse group of molecules fulfilling numerous functions such as energy storage and cell signaling.
To gain a better understanding of the lipidomic landscape in planarians we analyzed positive and negative ions from longitudinal sections of P. gracialis with MALDI-FTICR-MS and ToF-SIMS along with homogenized whole worm extracts with LC-MS/MS.
Imaging MALDI-FTICR-MS (15T, Bruker Solarix) provides location specific (50 µm/pixel ), ultra-high mass resolution (R≈250,000 @m/z=400) and ultra-high accuracy (<1ppm) lipid data capable of distinguishing intact lipid species of similar exact mass and showing their distribution in the tissue. The drawbacks for this technique are that the spatial resolution is too low to clearly identify features within the worm and its low fragmentation rate. While beneficial for molecular peak intensities, the lack of fragments does not allow for specific lipid assignments with structural information (e.g. lipid headgroup and both fatty acid chains identified).
Imaging GCIB-ToF-SIMS (J105, Ionoptika) generates high mass accuracy (< 5ppm), cell/organ-specific data (3 µm/pixel) consisting of intact lipids, lipid fragments and fatty acids. The moderate mass resolution (R≈10,000@m/z=700) is sufficient to resolve most lipid species. Mass peaks consisting of more than one species are indicated by broad and/or asymmetric peaks with poor mass accuracy. However co-localizing fragments can add confidence for the assignment of overlapping species, provide us with structural information and allow for unambiguous identification of resolved peaks.
LC-MS/MS (Thermo Velos Pro Orbitrap ) separates different lipid species prior to fragmentation so, in contrast to SIMS, the observed lipid fragments are guaranteed to stem from the analyzed species. The drawback with this technique is that it provides no location specific information. Similar to SIMS, lipids with similar mass are not separated leading to mixed fragments in the MS/MS data. Comparing LC-MS/MS to SIMS data shows that the same lipid fragment species are present in both spectra.
This work demonstrates that only by correlating all 3 techniques can we get highly accurate, high mass, high spatial resolution, structural and location specific lipid information. Together this data provides detailed information about all major structures and organs within planarians.