title: Does Parmelina tiliacea lichen photosystem II survive at liquid nitrogen temperatures?
abstract: Parmelina tiliacea lichens kept in the wet and dry state were stored in liquid nitrogen for 1 week and the subsequent recovery of their photosynthetic apparatus was followed. The chlorophyll a fluorescence rise and the maximum quantum yield of primary photochemistry φPo(FV/FM) were analysed for this purpose. Storage of wet thalli for 1 week in liquid nitrogen led to an impairment of photosystem II and probably the photosynthetic apparatus as a whole, from which the thalli did not recover over time. Thalli exposed in the dry state thalli were far less affected by the treatment and recovered well. These results indicate that the thalli are extremely tolerant to liquid nitrogen temperatures only in the dry state.
authors.affiliation: Mohammed VI Polytechnic University, School of Agriculture, Fertilizing and Environment, Ben Guerir, Morocco; Bioenergetics and Microbiology Laboratory, University of Geneva, CH-1254 Jussy-Geneva, Switzerland. Electronic address: oukarroum.abdallah@uqam.ca.
authors.forename: Abdallah
authors.initials: A
authors.lastname: Oukarroum
authors.affiliation: Mohammed VI Polytechnic University, School of Agriculture, Fertilizing and Environment, Ben Guerir, Morocco.
authors.forename: Mohamed
authors.initials: M
authors.lastname: El Gharous
authors.affiliation: Bioenergetics and Microbiology Laboratory, University of Geneva, CH-1254 Jussy-Geneva, Switzerland.
authors.forename: Reto J
authors.initials: RJ
authors.lastname: Strasser
mesh_terms: D002734:Chlorophyll / Q000737:chemistry*; D000077194:Chlorophyll A; D003080:Cold Temperature; D009584:Nitrogen; D000068837:Parmeliaceae / Q000201:enzymology / Q000378:metabolism*; D010777:Photochemistry; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000378:metabolism*
chemical_list: D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D009584:Nitrogen; D000077194:Chlorophyll A
keywords: Chlorophyll a fluorescence rise; Dry and wet state; Liquid nitrogen; Parmelina tiliacea