COST Workshop 2017, Bertinoro, Italy, March19-23, 2017
FTIR micro-spectroscopy: a tool to identify microfossils
Y. Cornet 1,*,E.J. Javaux 1
1Palaeobiogeobiology-Palaeobotany-Palaeopalynology, UR GEOLOGY, University of Liege, Liège, Belgium.
(*)
Fourier-Transform Infraredmicro-spectroscopy(FTIR) is a non-destructive analytical method using infrared radiations to induce vibrations in the chemical bonds present in organic material. Coupled to a microscope, micro-FTIR is increasingly used for determining the biological affinities oforganic-walled microfossils[1-3]. Many modern protists and some multicellular eukaryoteshave walls made of organic biopolymers. Due to some distinctive chemicalcharacteristics, these molecules are easilydistinguishable by FTIR analyses, and thus may help the identification of microfossils, including specific clades of eukaryotes. At least fivetypes of known biopolymers respond to these characteristics: algaenan, cellulose, chitin, dinosporin and sporopollenin. Others exist and some are preserved in organic-walled microfossils, but they remain to be characterized.Their recalcitrant composition may promote their preservation in the rock record.
Algaenan is a highly aliphatic biopolymer made of carbons chains cross-linked by ether and ester, mainly found inside a few green algae and some eustigmatophytes[4]. Cellulose, the most abundantbiopolymer, is made of polysaccharideforming long chains associated in microfibrils. It is mainly found in the higher plant taxa but also in some fungi and green, brown algae and cyanobacteria[5]. Chitin is another type of polysaccharide, found in three distinct structural allomorphs. It is the second most abundant biopolymer and one of the most widespread, being found in yeasts and other fungi, but also in sponges, protozoa and higher animal taxa [6]. Dinosporin is found inside the walls of some dinoflagellatecysts, but itscomposition is still debated [7]. Sporopollenin, one of the most resistant biopolymer, is made of aliphatic chains combined with oxygenated aromatic rings. It is exclusivelyfound within the walls of spores and pollens [8].
Comparing the wall composition of biologically unresolved microfossils to modern biopolymers may help to precise their taxonomy, especially in combination with morphological, structural and ultrastructural information.
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[3] Igisu, M., Ueno, Y., Shimojima M., Nakashima, S., Awramik, S.M., Ohta, H., Maruyama, S., 2009,Micro-FTIR spectroscopic signatures of Bacterial lipids in Proterozoic microfossils, Precambrian Research 173, 19-26
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[7] Bogus K., Harding, I.C., King, A., Charles, A.J., Zonneveld, K.A.F., Versteegh G.J.M., 2012, The composition and diversity of dinosporin in species of the Apectodinium complex (Dinoflagellata), Review of Palaeobotanny and Palynology 183, 21-31
[8] Mackenzie, G., Boa, A.N., Diego-Taboada, A., Atkin, S.L., Sathyapalan, T., 2015, Sporopollenin, the least known yet toughest natural biopolymer, Frontiers in Material 2, 1-5
I would like to have a Oralpresentation