Inactivation of vitamin B\u3csub\u3e6\u3c/sub\u3e by hydroxyurea in Aspergillus culture media

We found that sublethal levels of Hydroxyurea (HU), an inhibitor of ribonucleotide reductase, inhibited the growth of pyroA4 mutants of Aspergillus nidulans. Growth inhibition increased with the age of the HU-containing medium, and was remediated by supplementation with additional vitamin B6, indicating that HU leads to the inactivation of vitamin B6. HU inactivated vitamin B6 in the presence or absence of media components. These results demonstrate a direct affect of HU on vitamin B6, and they complicate the interpretation of results from experiments involving HU and fungal strains auxotrophic for vitamin B6

Increasing myosin light chain 3f (MLC3f) protects against a decline in contractile velocity

Disuse induces adaptations in skeletal muscle, which lead to muscle deterioration. Hindlimb-unloading (HU) is a well-established model to investigate cellular mechanisms responsible for disuse-induced skeletal muscle dysfunction. In myosin heavy chain (MHC) type IIB fibers HU induces a reduction in contraction speed (Vo) and a reduction in the relative myosin light chain 3f (MLC3f) protein content compared with myosin light chain 1f (MLC1f) protein. This study tested the hypothesis that increasing the relative MLC3f protein content via rAd-MLC3f vector delivery would attenuate the HU-induced decline in Vo in single MHC type IIB fibers. Fischer-344 rats were randomly assigned to one of three groups: control, HU for 7 days, and HU for 7 days plus rAd-MLC3f. The semimembranosus muscles were injected with rAd-MLC3f (3.75 x 1011-5 x 1011 ifu/ml) at four days after the initiation of HU. In single MHC type IIB fibers the relative MLC3f content decreased by 25% (12.00±0.60% to 9.06±0.66%) and Vo was reduced by 29% (3.22±0.14fl/s vs. 2.27±0.08fl/s) with HU compared to the control group. The rAd-MLC3f injection resulted in an increase in the relative MLC3f content (12.26±1.19%) and a concomitant increase in Vo (2.90±0.15fl/s) of MHC type IIB fibers. A positive relationship was observed between the percent of MLC3f content and Vo. Maximal isometric force and specific tension were reduced with HU by 49% (741.45±44.24μN to 379.09±23.77μN) and 33% (97.58±4.25kN/m2 to 65.05±2.71kN/m2), respectively compared to the control group. The rAd-MLC3f injection did not change the HU-induced decline in force or specific tension. Collectively, these results indicate that rAd-MLC3f injection rescues hindlimb unloading-induced decline in Vo in MHC type IIB single muscle fibers.Published versio

Large coupling behaviour of the Lyapunov exponent for tight binding one-dimensional random systems

Studies the Lyapunov exponent gamma lambda (E) of (hu)(n)=u(n+1)+u(n-1)+ lambda V(n)u(n) in the limit as lambda to infinity where V is a suitable random potential. The authors prove that gamma lambda (E) approximately ln lambda as lambda to infinity uniformly as E/ lambda runs through compact sets. They also describe a formal expansion (to order lambda -2) for random and almost periodic potentials

Bordetella pertussis, the Causative Agent of Whooping Cough, Evolved from a Distinct, Human-Associated Lineage of B. bronchiseptica

Bordetella pertussis, B. bronchiseptica, B. parapertussis(hu), and B. parapertussis(ov) are closely related respiratory pathogens that infect mammalian species. B. pertussis and B. parapertussis(hu) are exclusively human pathogens and cause whooping cough, or pertussis, a disease that has resurged despite vaccination. Although it most often infects animals, infrequently B. bronchiseptica is isolated from humans, and these infections are thought to be zoonotic. B. pertussis and B. parapertussis(hu) are assumed to have evolved from a B. bronchiseptica–like ancestor independently. To determine the phylogenetic relationships among these species, housekeeping and virulence genes were sequenced, comparative genomic hybridizations were performed using DNA microarrays, and the distribution of insertion sequence elements was determined, using a collection of 132 strains. This multifaceted approach distinguished four complexes, representing B. pertussis, B. parapertussis(hu), and two distinct B. bronchiseptica subpopulations, designated complexes I and IV. Of the two B. bronchiseptica complexes, complex IV was more closely related to B. pertussis. Of interest, while only 32% of the complex I strains were isolated from humans, 80% of the complex IV strains were human isolates. Comparative genomic hybridization analysis identified the absence of the pertussis toxin locus and dermonecrotic toxin gene, as well as a polymorphic lipopolysaccharide biosynthesis locus, as associated with adaptation of complex IV strains to the human host. Lipopolysaccharide structural diversity among these strains was confirmed by gel electrophoresis. Thus, complex IV strains may comprise a human-associated lineage of B. bronchiseptica from which B. pertussis evolved. These findings will facilitate the study of pathogen host-adaptation. Our results shed light on the origins of the disease pertussis and suggest that the association of B. pertussis with humans may be more ancient than previously assumed

One-step purification of histone-like protein (HU) from Halobacillus litoralis

The histone-like protein (HU) in bacteria is a small, basic, heat-stable protein that is involved in cell division and compression of the bacterial genome into a nucleoid. HU exists as a homodimer in most gram-positive bacteria such as Bacillus subtilis and as a heterodimer in enterobacteria such as Escherichia coli. The structure of HU, similar to other proteins, may change during purification, which may reduce the value of the investigation. Therefore, in this study, HU was purified in one step using an affinity chromatography column CNBr-activated Sepharose 4B matrix without using high-speed centrifugation and salting out methods. It was observed that the molecular weight and immunochemical properties of HU from Halobacillus litoralis were the same as those of HBsu (HU from B. subtilis)