Rapid determination of spore chemistry using thermochemolysis gas chromatography-mass spectrometry and micro-Fourier transform infrared spectroscopy.
Spore chemistry is at the centre of investigations aimed at producing a proxy record of harmful ultraviolet radiation (UV-B) through time. A biochemical proxy is essential owing to an absence of long-term (century or more) instrumental records. Spore cell material contains UV-B absorbing compounds that appear to be synthesised in variable amounts dependent on the ambient UV-B flux. To facilitate these investigations we have developed a rapid method for detecting variations in spore chemistry using combined thermochemolysis gas chromatography-mass spectrometry and micro-Fourier transform infrared spectroscopy. Our method was tested using spores obtained from five populations of the tropical lycopsid Lycopodium cernuum growing across an altitudinal gradient (650-1981 m a.s.l.) in S.E. Asia with the assumption that they experienced a range of UV-B radiation doses. Thermochemolysis and subsequent pyrolysis liberated UV-B pigments (ferulic and para-coumaric acid) from the spores. All of the aromatic compounds liberated from spores by thermochemolysis and pyrolysis were active in UV-B protection. The various functional groups associated with UV-B protecting pigments were rapidly detected by micro-FTIR and included the aromatic C[double bond, length as m-dash]C absorption band which was exclusive to the pigments. We show increases in micro-FTIR aromatic absorption (1510 cm(-1)) with altitude that may reflect a chemical response to higher UV-B flux. Our results indicate that rapid chemical analyses of historical spore samples could provide a record ideally suited to investigations of a proxy for stratospheric O3 layer variability and UV-B flux over historical (century to millennia) timescales.
Watson
Jonathan S
JS
Planetary and Space Sciences Research Institute, Open University, Milton Keynes, Buckinghamshire, UKMK7 6AA.
Sephton
Mark A
MA
Sephton
Sarah V
SV
Self
Stephen
S
Fraser
Wesley T
WT
Lomax
Barry H
BH
Gilmour
Iain
I
Wellman
Charles H
CH
Beerling
David J
DJ
D001704:Biopolymers / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006361:Heating; D006841:Hydrocarbons, Aromatic / Q000032:analysis; D006868:Hydrolysis; D032502:Lycopodium / Q000502:physiology; D010126:Ozone / Q000737:chemistry; D010860:Pigments, Biological / Q000032:analysis; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013170:Spores / Q000737:chemistry* / Q000528:radiation effects; D014466:Ultraviolet Rays / Q000009:adverse effects*
D001704:Biopolymers; D006841:Hydrocarbons, Aromatic; D010860:Pigments, Biological; D010126:Ozone