T2 New Voices in Geobiology

Sunday, 22 September 2024
8:00 AM - 12:00 PM
208A

INVESTIGATING THE MOLECULAR COMPOSITION OF MIDDLE ORDOVICIAN AND UPPER SILURIAN MICROFOSSILS USING MASS SPECTROMETRY AT THE MICROSCALE

Paper number: T2-8
Program: Technical Sessions
Time: 9:40 AM – 9:55 AM

Authors

  • Mathilde Bon Presenting Author
    UMR 8187 LOG Laboratoire d'Océanologie et de Géosciences, Lille
  • Mathilde Bon Presenting Author
    UMR 8523 - PhLAM, Laboratoire de Physique des Lasers, Atomes et Molécules, Lille
  • Mathilde Bon Presenting Author
    Ghent University, Ghent
  • Kevin Lepot
    UMR 8187 LOG Laboratoire d'Océanologie et de Géosciences, Lille
  • Yvain Carpentier
    UMR 8523 - PhLAM, Laboratoire de Physique des Lasers, Atomes et Molécules, Lille
  • Fabrice Bray
    UAR 3290 - MSAP Laboratoire Miniaturisation pour la Synthèse, l’Analyse et la Protéomique, Lille
  • Armelle Riboulleau
    UMR 8187 LOG Laboratoire d'Océanologie et de Géosciences, Lille
  • Nicolas Nuns
    FR 2638 - IMEC - Institut Michel-Eugène Chevreul, Lille
  • Christian Rolando
    UAR 3290 - MSAP Laboratoire Miniaturisation pour la Synthèse, l’Analyse et la Protéomique, Lille
  • Cristian Focsa
    UMR 8523 - PhLAM, Laboratoire de Physique des Lasers, Atomes et Molécules, Lille
  • Thijs R.A. Vandenbroucke
    Ghent University, Ghent

Abstract

The development of mass spectrometric analyses performed at the micrometric scale opens the opportunity to study the molecular composition of single specimens of organic-walled microfossils. This could help infer the composition of their original biopolymer, and eventually constrain the biological affinities of those fossils.

Here, we develop our methodology on the species Gloeocapsomorpha prisca (~10 μm), a probable cyanobacterium1,3,4,8, which forms up to 99% of the organic matter in “kukersite” rock (Ordovician, 460 Ma) from northwest Russia6. In parallel, we analyse two unicellular prasinophyte green algae, Tasmanites and Cymatiosphaera nimia, isolated from a rock sample (Silurian, 419 Ma) of western Libya5,7.

The molecular composition of these microfossils is analysed by laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (LDI-FT-ICR-MS) ~ 13 μm laser spot , high-resolution two-step laser mass spectrometry (HR-L2-MS) ~ 140 μm laser spot, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) ~1μm spatial resolution.

The HR-L2-MS spectrum of bulk G. prisca dominated by abundant (poly)aromatic hydrocarbon and oxygenated derivatives. ToF-SIMS spectra are dominated by small hydrocarbons, including fragments of aliphatic species. LDI-FT-ICR-MS spectra for G. prisca show a dominance of oxygenated derivatives (in particular with O2), followed by nitrogen derivatives and aromatic hydrocarbons. For Tasmanites and Cymatiosphaera nimia the dominant families are nitrogenated derivatives and aromatic hydrocarbons.

The oxygenated functions in LDI-FT-ICR-MS are consistent with the composition of G. prisca analyzed by (micro)pyrolysis and chemolysis1,2,3,8. Marked differences in molecular compositions in LDI-FT-ICR-MS of biopolymers from individualized specimens of G. prisca, Tasmanites and C. nimia highlight the potential of mass spectrometric methods for chemotaxonomy.

1Blokker P et al 2001 DOI: 10.1016/S0016-7037(00)00582-2

2Derenne S et al 1990 DOI : 10.1016/0146-6380(90)90124-I

3Derenne S et al 1992 DOI: 10.1016/0146-6380(92)90001-E

4Kiipli E et al 2013 DOI: 10.3176/oil.2013.1.06

5Le Hérissé A et al 2002 DOI: 10.1016/S0034-6667(01)00123-3

6Raevskaya E et al 2004

7Rubinstein C et al 2002 DOI: 10.1016/S0034-6667(01)00124-5

8da Silva T F D et al 2016 DOI: 71–79. 10.1016/j.coal.2016.08.010

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-404561

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