Weakening of the ultraviolet ray-induced unscheduled DNA synthesis in human lymphocytes in extreme old age

The intensity of unscheduled DNA synthesis was studied in UV-irradiated (10--15 J/m2) peripheral blood lymphocytes of 80--90 years old persons. In these extreme old age persons, reparative DNA synthesis was found sufficiently reduced in comparison with that in middle aged (20--43 years old) ones. The role of DNA repair processes in ageing is under discussion.     

Rapid SNP diagnostics using asymmetric isothermal amplification and a new mismatch-suppression technology

We developed a rapid single nucleotide polymorphism (SNP) detection system named smart amplification process version 2 (SMAP 2). Because DNA amplification only occurred with a perfect primer match, amplification alone was sufficient to identify the target allele. To achieve the requisite fidelity to support this claim, we used two new and complementary approaches to suppress exponential background DNA amplification that resulted from mispriming events. SMAP 2 is isothermal and achieved SNP detection from whole human blood in 30 min when performed with a new DNA polymerase that was cloned and isolated from Alicyclobacillus acidocaldarius (Aac pol). Furthermore, to assist the scientific community in configuring SMAP 2 assays, we developed software specific for SMAP 2 primer design. With these new tools, a high-precision and rapid DNA amplification technology becomes available to aid in pharmacogenomic research and molecular-diagnostics applications.     

Allogeneic T cells treated with amotosalen prevent lethal cytomegalovirus disease without producing graft-versus-host disease following bone marrow transplantation

Infusion of donor antiviral T cells can provide protective immunity for recipients of hemopoietic progenitor cell transplants, but may cause graft-vs-host disease (GVHD). Current methods of separating antiviral T cells from the alloreactive T cells that produce GVHD are neither routine nor rapid. In a model of lethal murine CMV (MCMV) infection following MHC-mismatched bone marrow transplantation, infusion of MCMV-immune donor lymphocytes pretreated with the DNA cross-linking compound amotosalen prevented MCMV lethality without producing GVHD. Although 95% of mice receiving 30 x 10(6) pretreated donor lymphocytes survived beyond day +100 without MCMV disease or GVHD, all mice receiving equivalent numbers of untreated lymphocytes rapidly died of GVHD. In vitro, amotosalen blocked T cell proliferation without suppressing MCMV peptide-induced IFN-gamma production by MCMV-primed CD8(+) T cells. In vivo, pretreated lymphocytes reduced hepatic MCMV load by 4-log(10) and promoted full hemopoietic chimerism. Amotosalen-treated, MCMV tetramer-positive memory (CD44(high)) CD8(+) T cells persisted to day +100 following infusion, and expressed IFN-gamma when presented with viral peptide. Pretreated T cells were effective at preventing MCMV lethality over a wide range of concentrations. Thus, amotosalen treatment rapidly eliminates the GVHD activity of polyclonal T cells, while preserving long-term antiviral and graft facilitation effects, and may be clinically useful for routine adoptive immunotherapy.     

Cloning and analysis of the telomere and terminal inverted repeat of the linear chromosome of Streptomyces griseus

Cloning and sequencing of the telomere of Streptomyces griseus revealed five palindromic sequences in the terminal 116 nucleotides, all of which can make a hairpin loop structure. However, the end sequence cannot form the foldback secondary structure that is common in Streptomyces telomeres and is suggested to be necessary for terminal replication. Both inside ends of the terminal inverted repeat (TIR) were also cloned and sequenced. The results confirmed the size of the TIR to be 24 kb and identified two almost identical open reading frames that might have been involved in the formation of the TIR.     

Peptide Epitalon activates chromatin at the old age

OBJECTIVES and design. We have studied the effect of synthetic peptide Epitalon on the activity of ribosomal genes, denaturation parameters of total heterochromatin, polymorphism of structural C-heterochromatin and the variability of facultative heterochromatin in cultured lymphocytes of persons aged 76-80 years. RESULTS: The obtained data demonstrate that Epitalon induces the activation of ribosomal genes, decondensation of pericentromeric structural heterochromatin and the release of genes repressed due to the age-related condensation of euchromatic chromosome regions. CONCLUSIONS: Epitalon has shown its ability to activate chromatin by modifying heterochromatin and heterochromatinized chromosome regions in the cells of older persons.     

Effect of thiazole orange doubly labeled thymidine on DNA duplex formation

Nucleic acid oligonucleotides are widely used in hybridization experiments for specific detection of complementary nucleic acid sequences. For design and application of oligonucleotides, an understanding of their thermodynamic properties is essential. Recently, exciton-controlled hybridization-sensitive fluorescent oligonucleotides (ECHOs) were developed as uniquely labeled DNA oligomers containing commonly one thymidine having two covalently linked thiazole orange dye moieties. The fluorescent signal of an ECHO is strictly hybridization-controlled, where the dye moieties have to intercalate into double-stranded DNA for signal generation. Here we analyzed the hybridization thermodynamics of ECHO/DNA duplexes, and thermodynamic parameters were obtained from melting curves of 64 ECHO/DNA duplexes measured by ultraviolet absorbance and fluorescence. Both methods demonstrated a substantial increase in duplex stability (ΔΔG°(37) ～ -2.6 ± 0.7 kcal mol(-1)) compared to that of DNA/DNA duplexes of the same sequence. With the exception of T·G mismatches, this increased stability was mostly unaffected by other mismatches in the position opposite the labeled nucleotide. A nearest neighbor model was constructed for predicting thermodynamic parameters for duplex stability. Evaluation of the nearest neighbor parameters by cross validation tests showed higher predictive reliability for the fluorescence-based than the absorbance-based parameters. Using our experimental data, a tool for predicting the thermodynamics of formation of ECHO/DNA duplexes was developed that is freely available at http://genome.gsc.riken.jp/echo/thermodynamics/ . It provides reliable thermodynamic data for using the unique features of ECHOs in fluorescence-based experiments.     

Chromosomal deletions in Streptomyces griseus that remove the afsA locus

We have recently constructed a physical map of the Streptomyces griseus 2247 genome using the restriction enzymes AseI and DraI, which revealed that this strain carries a 7.8 Mb linear chromosome. Based on this map, precise macrorestriction fragment and cosmid maps were constructed for both ends of the chromosome, which localized the afsA gene 150 Kb from the left end. Two afsA ^? mutants were found to have suffered chromosomal deletions that removed the afsA locus. The sizes of the deletions were 20 and 130 Kb at the right end and 180 and 350 kb at the left end, respectively. Hybridization experiments using cosmids carrying a deletion endpoint indicated that the ends of the chromosome in the mutants were fused to form a circular chromosome.