title: Hyperspectral imaging of snow algae and green algae from aeroterrestrial habitats.
abstract: Snow algae and green algae living in aeroterrestrial habitats are ideal objects to study adaptation to high light irradiation. Here, we used a detailed description of the spectral properties as a proxy for photo-acclimation/protection in snow algae (Chlamydomonas nivalis, Chlainomonas sp. and Chloromonas sp.) and charophyte green algae (Zygnema sp., Zygogonium ericetorum and Klebsormidium crenulatum). The hyperspectral microscopic mapping and imaging technique allowed us to acquire total absorption spectra of these microalgae in the waveband of 400-900nm. Particularly in Chlamydomonas nivalis and Chlainomonas sp., a high absorbance between 400-550nm was observed, due to naturally occurring secondary carotenoids; in Chloromonas sp. and in the charopyhte algae this high absorbance was missing, the latter being close relatives to land plants. To investigate if cellular water loss has an influence on the spectral properties, the cells were plasmolysed in sorbitol or desiccated at ambient air. While in snow algae, these treatments did hardly change the spectral properties, in the charopyhte algae the condensation of the cytoplasm and plastids increased the absorbance in the lower waveband of 400-500nm. These changes might be ecologically relevant and photoprotective, as aeroterrestrial algae are naturally exposed to occasional water limitation, leading to desiccation, which are conditions usually occurring together with higher irradiation.
authors.affiliation: Institute of Botany, Functional Plant Biology, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria. Electronic address: Andreas.Holzinger@uibk.ac.at.
authors.forename: Andreas
authors.initials: A
authors.lastname: Holzinger
authors.affiliation: Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0202, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Allen
authors.affiliation: Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0202, USA. Electronic address: ddeheyn@ucsd.edu.
authors.forename: Dimitri D
authors.initials: DD
authors.lastname: Deheyn
mesh_terms: D002696:Chlamydomonas / Q000166:cytology*; D003890:Desiccation; D017753:Ecosystem; D057054:Molecular Imaging
keywords: Carotenoids; Green algae; Hyperspectral imaging; Pigments; Stress tolerance