Humidity interaction of lichens under astrobiological aspects: the impact of UVC exposure on their water retention properties. Issue 3 (July 2015)

• Record Type: Journal Article
• Authors: Jänchen, J.; Meeßen, J.; Herzog, T.H.; Feist, M.; de la Torre, R.; deVera, J.-P.P.
• Is Part Of: International journal of astrobiology. Volume 14:Issue 3(2015:Jul.)
• Page Start: 445
• Page End: 456
• Publication Date: 2015-07
• Subjects: Exobiology -- Periodicals; 576.83905
• DOI: 10.1017/S147355041500004X
• Languages: English
• ISSNs: 1473-5504

Abstract

<abstract abstract-type="normal"> <title>Abstract</title> <p>We quantitatively studied the hydration and dehydration behaviour of the three astrobiological model lichens <italic>Xanthoria elegans, Buellia frigida</italic> and <italic>Circinaria gyrosa</italic> by thermoanalysis and gravimetric isotherm measurements under close-to-Martian environmental conditions in terms of low temperature and low pressure. Additionally, the impact of UVC exposure on the isolated symbionts of <italic>B. frigida</italic> and <italic>X. elegans</italic> was studied by thermoanalysis and mass spectrometry as well as by gravimetric isotherm measurements. The thermal analysis revealed whewellite as a component of <italic>C. gyrosa</italic> which was not found in <italic>B. frigida</italic> and <italic>X. elegans</italic>. Neither the water retention nor the thermal behaviour of symbionts changed when irradiated with UVC under dry conditions. On the other hand, UVC irradiation of the wet mycobiont of <italic>B. frigida</italic> had a distinct impact on the hydration/dehydration ability which was not observed for the mycobiont of <italic>X. elegans</italic>. Possibly the melanin of <italic>B. frigida's</italic> mycobiont, that is not present in <italic>X. elegans</italic>, or a specifically damaged acetamido group of the chitin of <italic>B. frigida</italic> may be the sources of additional UVC-induced sorption sites for water associated with the UVC exposure.</p> </abstract>