Genomic DNA of Nostoc commune (Cyanobacteria) becomes covalently modified during long-term (decades) desiccation but is protected from oxidative damage and degradation

Abstract

Genomic DNA of Nostoc commune (Cyanobacteria) became covalently modified during decades of desiccation. Amplification of gene loci from desiccated cells required pretreatment of DNA with N-phenacylthiazolium bromide, a reagent that cleaves DNA- and protein-linked advanced glycosylation end-products. DNA from 13 year desiccated cells did not show any higher levels of the commonly studied oxidatively modified DNA damage biomarkers 8-hydroxyguanine, 8-hydroxyadenine and 5-hydroxyuracil, compared to commercially available calf thymus DNA. Different patterns of amplification products were obtained with DNA from desiccated/rehydrating cells and a liquid culture derived from the dried material, using the same set of primers. In contrast, a reproducible fingerprint was obtained, irrespective of time of rehydration of the DNA, using a primer (5'-GWCWATCGCC-3') based upon a highly iterated palindromic repeat sequence present in the genome. In vitro, the desiccation of cccDNA led to loss of supercoiling, aggregation, loss of resolution during agarose gel electrophoresis and loss of transformation and transfection efficiency. These changes were minimized when DNA was desiccated and stored in the presence of trehalose, a non-reducing disaccharide present in Nostoc colonies. The response of the N.commune genome to desiccation is different from the response of the genomes of cyanobacteria and Deinococcus radiodurans to ionizing radiation.

Assessing a novel room temperature DNA storage medium for forensic biological samples

“…Best results occurred for DNA in the presence of trehalose stored dried at room temperature or at À80 8C, although significant quality loss was detected with À20 8C and +4 8C storage. Studies with trehalose as an additive for dried room temperature plasmid DNA storage indicates initial protection from degradation and light-induced damage; but after 8 weeks degradation was observed [18]. Plasmids are in general more stable than genomic DNA samples and even after only 2 weeks at À20 8C using highly purified trehalose, DNA showed signs of degradation [13].…”

“…Plasmids are in general more stable than genomic DNA samples and even after only 2 weeks at À20 8C using highly purified trehalose, DNA showed signs of degradation [13]. Other sugars such as sucrose, glucose and lactose have been studied for their ability to stabilize purified dried DNA, however trehalose had the highest stability for all sugar based stabilizers [18].…”

Mutations Stabilize Small Subunit Ribosomal RNA in Desiccation-Tolerant Cyanobacteria Nostoc

“…Nostoc cells experience extremes of desiccation, of which the water content is 0.02 to 0.05 g water cell solid -1 , approximately one order of magnitude lower than that of eubacterial spores (0.21 to 0.58) [27]. The mechanisms involved in the desiccation tolerance of Nostoc have been investigated using ecophysiology, biochemistry, and molecular biology [13,30,31,36]. However, the stability and biophysical properties of macromolecules inside desiccated cells are still poorly understood.…”

“…However, the stability and biophysical properties of macromolecules inside desiccated cells are still poorly understood. Even though modifications of genome DNA, such as hypermethylation, have been observed in old desiccated sample of Nostoc species [15,31], it is unclear what effects these modifications have on the fitness of the desiccated cells.The ribosomal RNA molecule is an ideal model for evaluating the stability of a gene product and a suitable fitness indicator in evolutionary studies [4,18,29]. Because ribosomal RNA molecules create the structural framework for the ribosome, the sequences represent not only genotypes but also structural phenotypes.…”

“…However, the stability and biophysical properties of macromolecules inside desiccated cells are still poorly understood. Even though modifications of genome DNA, such as hypermethylation, have been observed in old desiccated sample of Nostoc species [15,31], it is unclear what effects these modifications have on the fitness of the desiccated cells.…”