The Roles of the Anthraquinone Parietin in the Tolerance to Desiccation of the Lichen : Physiology and Anatomy of the Pale and Bright-Orange Thalli.

Lichens are symbiotic organisms that effectively survive in harsh environments, including arid regions. Maintaining viability with an almost complete loss of water and the rapid restoration of metabolism during rehydration distinguishes lichens from most eukaryotic organisms. The lichen is known to have high stress tolerance, possessing diverse defense mechanisms, including the presence of the bright-orange pigment parietin.

Structural details of pectic galactan from the secondary cell walls of flax (Linum usitatissimum L.) phloem fibres.

Details of the backbone and side chain structure of pectic β-(1→4)-galactan from the secondary cell walls of flax phloem fibres were characterised by NMR and mass spectrometry of the fragments obtained after partial hydrolysis with specific endogalactanase and rhamnogalacturonan hydrolase. The proportions of branched and linear rhamnose in the backbone of the polymer equalled 72% and 28%, respectively. Rhamnose branched with a single galactose residue comprised 47% of the total rhamnose; thus, in the bulk of the polymer backbone, rhamnose had 0-1 galactose residues.