A simple kinetic parameter indicating the origin of the relaxations induced by point(-like) defects in metallic crystals and glasses.

Computer simulation shows that an increase of the volume V due to point defects in a simple metallic crystal (Al) and high entropy alloy (Fe20Ni20Cr20Co20Cu20) leads to a linear decrease of the shear modulus G. This diaelastic effect can be characterized by a single dimensionless parameter K = dln G/dln V. For dumbbell interstitials in single crystals K ≈ -30 while for vacancies the absolute K-value is smaller by an order of magnitude. In the polycrystalline state, K ≈ -20 but its the absolute value remains anyway 5-6 times larger than that for vacancies. The physical origin of this difference comes from the fact that dumbbell interstitials constitute elastic dipoles with highly mobile atoms in their nuclei and that is why produce much larger shear softening compared to vacancies. For simulated Al and high entropy alloy in the glassy state, K equals to -18 and -12, respectively. By the absolute magnitude, these values are by several times larger compared to the case of vacancies in the polycrystalline state of these materials. An analysis of the experimental data on isothermal relaxations of G as a function of V for six Zr-based metallic glasses tested at different temperatures shows that K is time independent and equals to ≈-43, similar to interstitials in single-crystals. It is concluded that K constitutes a important simple kinetic parameter indicating the origin of relaxations induced by point(-like) defects in the crystalline and glassy states.

Maintenance of genome stability: the unifying role of interconnections between the DNA damage response and RNA-processing pathways.

Endogenous and exogenous factors can severely affect the integrity of genetic information by inducing DNA damage and impairing genome stability. The protection of genome integrity is ensured by the so-called "DNA damage response" (DDR), a set of evolutionary-conserved events that, triggered upon DNA damage detection, arrests the cell cycle, and attempts DNA repair. Here, we review the role of the DDR proteins as post-transcriptional regulators of gene expression, in addition to their roles in DNA damage recognition, signaling, and repair. At the same time, we discuss recent insights into how pre-mRNA splicing factors go beyond their splicing activities and play direct functions in detecting, signaling, and repairing DNA damage. The importance of extensive two-way crosstalk and interaction between the RNA processing and the DDR stems from growing evidence that the defects of their communication lead to genomic instability.

New insights into the role of NF1 in cancer.

NF1 proteins are a family of transcription factors that act either as repressors or as activators. Functional studies indicate that NF1 participate in signaling pathways that regulate cell viability, proliferation and differentiation. Participation in regulation of genes important for tumor progression and metastasizing suggests a potential value of NF1 as a prognostic factor for certain types of cancer.

Molecular analysis of 16S-23S spacer regions of Acetobacter species.

16S-23S rDNA internal transcribed spacer regions (ITS) similarities were determined in 8 Acetobacter and 1 Gluconacetobacter strains. ITS-PCR amplification of the 16S-23S spacers showed 2 products of similar size in 7 strains; only 1 product of similar size was found in the 2 remaining strains. Analysis of the PCR products using restriction endonucleases HaeIII, HpaII and AluI revealed 3 different restriction groups of A. pasteurianus for AluI and HaeIII, and 4 restriction groups for HpaII. ITS nucleotide sequences of all studied strains exhibited a 52-98% similarity.