Although chlorophyll and its precursors are known to be sensitive to photooxidation when extracted, irreversible photooxidation damage seems to be rare when these molecules are retained in desiccated organisms. For instance, the desiccation tolerant cyanobacterium Nostoc commune has been shown to retain its pigments over 100 years of desiccation in a herbarium collection and revive immediately after water addition. Pigments were even found preserved in silicified Proterozoic stromatolites. This suggests that these molecules are extremely stable and remain largely intact in desiccated cells. Reduced degradation of these molecules under desiccation conditions could additionally be attributed to limited heterotrophic microbial activities. Using chlorophyll fluorescence analysis, it was shown that desiccated mosses, lichens and even cyanobacteria protect their photosynthetic apparatus from photooxidation by reducing the ground chlorophyll fluorescence to almost zero, a process known as fluorescence quenching. This process was recently described in intact desiccation tolerant cyanobacterial crusts from China. We conclude that desiccation-tolerant cyanobacteria in crusts have developed unique mechanisms to survive drying and wetting episodes. Their photosynthetic apparatus remain essentially intact and return to a functional state with remarkable speed. In the Omani crusts, cyanobacteria did not exhibit any hydrotactic movement to track water but instead increased their Chl a production and restored their photosynthetic activities within minutes of water addition. Mitochondria, which originated through the endosymbiosis of a-proteobacteria into ancestral host cells, are the cellular powerhouses and play vital roles in diverse eukaryotic cell processes through the production of ATP and various metabolic intermediates. Recent studies also suggest that dysfunctional mitochondria are involved in many neurodegenerative diseases such as aging and cognitive decline in a wide range of metazoans, including humans. Maintaining the structural and metabolic integrity of this semi-autonomous organelle is MK-2206 Akt inhibitor essential for the normal function of eukaryotic cells. Nevertheless, over the course of symbiotic evolution, the majority of mitochondrial genes migrated into the nuclear genome of the original host, leaving an incomplete set of essential genes in the mitochondrial genomes of most organisms, including plants. Complicated and dynamic communication and coordination between the nucleus and mitochondria greatly impact many fundamental cellular processes in, and even the lives of, most eukaryotes. Indeed, based on the complete sequence of the Arabidopsis mitochondrial genome, it has been reported that 57 mitochondrial genes encode the subunits of multiprotein complexes that are required for the respiratory chain, heme and cytochrome assembly, and mitochondrial ribosomes.