Cyanobacterium Nostoc commune can tolerate the simultaneous stresses of desiccation, UV irradiation, and oxidation. Acidic WspA, of ϳ33.6 kDa, is secreted to the three-dimensional extracellular matrix and accounts for greater than 70% of the total soluble protein. The wspA gene of N. commune strain DRH1 was cloned and found in a single genomic copy, in a monocistronic operon. Transcription of wspA and sodF (superoxide dismutase), and synthesis and secretion of WspA, were induced upon desiccation or UV-A/B irradiation of cells. Recombinant WspA binds the UV-A/B absorbing pigment scytonemin through non-covalent interactions. WspA peptide polymorphism, and heterogeneity of multiple wspA sequences within cells of a single colony, account for distinct WspA isoforms. WspA has no similarity to entries in the sequence databases and wspA, a possible xenolog, is restricted to a subset of strains in the "form species" N. commune characterized through group I intron phylogeny. We hypothesize that WspA plays a central role in the global stress response of N. commune through modulation of the structure and function of the three-dimensional extracellular matrix, particularly the transport, distribution, and/or macromolecular architecture of mycosporine and scytonemin UV-A/B absorbing pigment complexes.Cyanobacteria make a major contribution to world photosynthesis and nitrogen fixation, but their dense and often toxic "blooms" in marine, brackish, and fresh waters are of growing concern to public health (1). The sequences of a wide range of cyanobacterial genomes are becoming available and constitute an important resource both for the rational management and exploitation of these organisms, as well as the study of topics as diverse as carbon fixation, cell differentiation, plant and fungal symbioses, secondary product biosynthesis, and evolution.

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.

Sulfolobus sulfataricus ATCC 35091, Haloferax volcanii, and Methanosarcina thermophila TM-1, representing the Euryarchaeota and Crenarchaeota subdomains of the Archaea, contain proteins which are phosphorylated on tyrosine. These data raise fundamental questions as to the origin and evolution of tyrosine phosphorylation, a protein modification that is of pivotal importance in the regulation of the physiology of eukaryotic cells.Eukaryotic cells contain numerous protein-tyrosine kinases and phosphatases that regulate the phosphorylation and dephosphorylation of target proteins on tyrosine (7,18,20,21). These modification events are crucial for the regulation of enzyme activity and cellular functions, and a dysfunction in one or more of them can lead to cell transformation. Until very recently it was assumed that tyrosine phosphorylation was unique to eukaryotic cells and was an event which arose comparatively late in evolutionary history. Although a eukaryotelike protein-tyrosine phosphatase is known to be encoded by the virulence plasmid of Yersinia pestis, the general opinion is that the gene encoding this enzyme was acquired from the host cell (reviewed in reference 9). The finding of a dual-specificity protein tyrosine phosphatase, IphP, encoded by the genome of the cyanobacterium Nostoc commune UTEX 584 raised provocative questions concerning the origin of tyrosine phosphorylation (15). Now, it appears that tyrosine-phosphorylated (Ptyr) proteins and protein-tyrosine phosphatases occur in a range of different representatives of the Bacteria (4-6, 8-10, 14, 16, 19, 22). Here we present the first report of P-tyr proteins in representatives from the Archaea.Archaeal strains and growth conditions. Sulfolobus sulfataricus ATCC 35091 was grown at 75ЊC, with vigorous shaking, on de Rosa's standard medium with the concentration of yeast extract increased to 0.2 g liter Ϫ1 (3). Haloferax volcanii was provided by W. Ford Doolittle and was grown at 37ЊC, with vigorous shaking, in a mixture of 12.5% (wt/vol) NaCl, 5% (wt/vol) MgCl 2 ⅐ 6H 2 O, 0.5% (wt/vol) K 2 SO 4 , 0.012% (wt/vol) CaCl 2 , 0.5% (wt/vol) tryptone, and 0.5% (wt/vol) yeast extract which was adjusted to pH 7.2 with 1 M NaOH (12). Cell paste of Methanosarcina thermophila TM-1 (23) was provided by J. Greg Ferry. The organism was grown on acetate, at pH 10, in an auxostat as described previously (17). All cells were in the late logarithmic phase of growth at the time of harvesting.Protein purification. Cells were harvested by centrifugation and dispersed in a ratio of 1:1 with lysis buffer. Lysis buffer contained 50 mM HEPES (pH 7.5), 20 mM MgCl 2 , 20 mM KCl, 100 mM NaCl, 1 mM EDTA, 1 mM dithiothreitol, 1 mM ␤-mercaptoethanol, 1 mM sodium orthovanadate, 1 mM sodium fluoride, 0.1% (wt/vol) Tween 20, 1 M leupeptin, 0.07 M benzamidine, 0.01% (wt/vol) thimerosal, 25 M diisopropyl fluorophosphate, and 50 M phenylmethylsulfonyl fluoride. To disrupt the cells, the suspension was ground with alumina powder (type A-5; Sigma catalog no. A 2039) in a chilled mortar. ...

Nine patients receiving maintenance high-efficiency hemodialysis were studied before and after a 12-week conditioning program to determine the efficacy of exercise immediately following hemodialysis. Each patient performed a combination of bicycle ergometry on the Schwinn Air-Dyne ergometer (SAE) and treadmill walking three times a week for a total exercise time of 15–35 min per session. A low-level Bruce treadmill test and an exercise test on the SAE were administered before and after training. Hematological, serum electrolyte, and serum lipid profiles were also determined before and after training. Following training, there were improvements in exercise capacities for both treadmill walking and ergometry on the SAE. Although a significant increase in serum apolipo-protein Al was seen following exercise, no significant changes were observed for total cholesterol, low-density -lipoprotein cholesterol, high-density-lipoprotein cholesterol or apolipoprotein B. Additionally, no significant changes were seen in hematological parameters and serum electrolyte profiles following the exercise program. The 9 patients demonstrated an average compliance record of 74%. This study demonstrated that patients on high-efficiency hemodialysis can safely engage in an exercise program immediately following dialysis at intensities and frequencies that can improve their physical work capacities.

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