Acoustic Issues in Open Plan Offices: A Typological Analysis

This paper reports the acoustic issues of open plan office environments. According to a detailed research based on the scientific literature of the most suitable acoustic descriptors recommended for the open plan offices analysis, the main typological-functional configurations of these environments have been analyzed in order to identify six spatial typologies. The variation of acoustic parameters of these typologies has been evaluated by using a sound pyramid tracing software. The analysis procedure was calibrated in a case study of an office environment, where a measurement campaign was carried out. Results point out that the acoustic improvement of open plan offices can usually be achieved by introducing a sound absorbing false ceiling and dividing panels between working positions, but there are different issues depending on spatial geometries of the office. Better results are referred to office typologies characterized by reduced height and equal plan dimensions

DNA condensation and self-aggregation of Escherichia coli Dps are coupled phenomena related to the properties of the N-terminus

Escherichia coli Dps (DNA-binding proteins from starved cells) is the prototype of a DNA-protecting protein family expressed by bacteria under nutritional and oxidative stress. The role of the lysine-rich and highly mobile Dps N-terminus in DNA protection has been investigated by comparing the self-aggregation and DNA-condensation capacity of wild-type Dps and two N-terminal deletion mutants, DpsΔ8 and DpsΔ18, lacking two or all three lysine residues, respectively. Gel mobility and atomic force microscopy imaging showed that at pH 6.3, both wild type and DpsΔ8 self-aggregate, leading to formation of oligomers of variable size, and condense DNA with formation of large Dps–DNA complexes. Conversely, DpsΔ18 does not self-aggregate and binds DNA without causing condensation. At pH 8.2, DpsΔ8 and DpsΔ18 neither self-aggregate nor cause DNA condensation, a behavior also displayed by wild-type Dps at pH 8.7. Thus, Dps self-aggregation and Dps-driven DNA condensation are parallel phenomena that reflect the properties of the N-terminus. DNA protection against the toxic action of Fe(II) and H(2)O(2) is not affected by the N-terminal deletions either in vitro or in vivo, in accordance with the different structural basis of this property

DNA condensation and self-aggregation of Escherichia coli DPS are coupled phenomena related to the properties of the N-terminus

Escherichia coli Dps (DNA-binding proteins from starved cells) is the prototype of a DNA-protecting protein family expressed by bacteria under nutritional and oxidative stress. The role of the lysine-rich and highly mobile Dps N-terminus in DNA protection has been investigated by comparing the self-aggregation and DNA-condensation capacity of wild-type Dps and two N-terminal deletion mutants, DpsDelta8 and DpsDelta18, lacking two or all three lysine residues, respectively. Gel mobility and atomic force microscopy imaging showed that at pH 6.3, both wild type and DpsDelta8 self-aggregate, leading to formation of oligomers of variable size, and condense DNA with formation of large Dps-DNA complexes. Conversely, DpsDelta18 does not self-aggregate and binds DNA without causing condensation. At pH 8.2, DpsDelta8 and DpsDelta18 neither self-aggregate nor cause DNA condensation, a behavior also displayed by wild-type Dps at pH 8.7. Thus, Dps self-aggregation and Dps-driven DNA condensation are parallel phenomena that reflect the properties of the N-terminus. DNA protection against the toxic action of Fe(II) and H2O2 is not affected by the N-terminal deletions either in vitro or in vivo, in accordance with the different structural basis of this property

Upstream promoter sequences and αCTD mediate stable DNA wrapping within the RNA polymerase–promoter open complex

We show that the extent of stable DNA wrapping by Escherichia coli RNA polymerase (RNAP) in the RNAP–promoter open complex depends on the sequence of the promoter and, in particular, on the sequence of the upstream region of the promoter. We further show that the extent of stable DNA wrapping depends on the presence of the RNAP α-subunit carboxy-terminal domain and on the presence and length of the RNAP α-subunit interdomain linker. Our results indicate that the extensive stable DNA wrapping observed previously in the RNAP–promoter open complex at the λ P(R) promoter is not a general feature of RNAP–promoter open complexes