The elemental changes occurring in the rat liver after exposure to PEG-coated iron oxide nanoparticles: total reflection x-ray fluorescence (TXRF) spectroscopy study

The main goal of this study was to evaluate in vivo effects of low dose of PEG-coated magnetic iron oxide nanoparticles (IONPs) on the rat liver. The IONPs was intravenously injected into rats at a dose equaled to 0.03?mg of Fe per 1?kg of an animal body weight. The elemental composition of liver tissue in rats subjected to IONPs action and controls were compared. Moreover, in order to determine the dynamics of nanoparticles (NPs) induced elemental changes, the tissues taken from animals 2?hours, 24?hours, and 7?days from IONPs injection were examined. The analysis of subtle elemental anomalies occurring as a result of IONPs action required application of highly sensitive analytical method. The total reflection X-ray fluorescence spectroscopy perfectly meets such requirements and therefore it was used in this study. The obtained results showed increasing trend of Fe level within liver occurring 2?hours from IONPs injection. One day after NPs administration, the liver Fe content presented the baseline level what suggests only the short-term accumulation of nanoparticles in the organ. The Ca, Cu, and Zn levels changed significantly as a result of NPs action. Moreover, the anomalies in their accumulation were still observed 7?days after IONPs injection. The level of Cu decreased while those of Ca and Zn increased in the liver of NPs-treated animals. The reduced liver Cu, followed by elevated serum level of this element, might be related in triggering the mechanisms responsible for Fe metabolism in the organism.     

Reciprocal behaviour associated with altered homeostasis and photosensitivity of Drosophila clock mutants

The circadian oscillators of genetically short-period and long-period Drosophila exhibit reciprocal behaviour in four distinct ways: (1) with respect to the dependence of period on temperature, (2) in the change of period during constant darkness after ten days of constant light, (3) in the change of period during the second ten days of darkness as compared with the period during the first ten days, and (4) in the period change resulting from exposure to low-intensity constant light. The homeostatic control of the dependence of period length on temperature is impaired in the mutants as compared with wild-type files. The normal Drosophila pacemaker may comprise two mutually coupled oscillators, whereas the mutants may represent a reduction in activity of one or the other constituent oscillator.     

The spectrum of spontaneous mutations caused by deficiency in proteasome maturase Ump1 in Saccharomyces cerevisiae

Ump1 is responsible for maturation of the catalytic core of the 26S proteasome. Dysfunction of Ump1 causes an increase in the frequency of spontaneous mutations in Saccharomyces cerevisiae. In this study we analyze the spectrum of mutations occurring spontaneously in yeast deficient in Ump1 by use of the SUP4-o system. Single base substitutions predominate among the mutations analyzed (73 of the 91 alterations examined). Two major classes are GC to TA transversions and GC to AT transitions ( approximately 50 and approximately 30% of base substitutions, respectively). Besides base substitutions, almost all the major types of sequence alterations are represented. The specificity and distribution of mutations occurring in the ump1 strain are unique compared to the spectra previously established for other yeast mutators. However, the profile of mutations arising in this strain is similar to that observed in wild type. The same similarity has previously been reported for yeast deficient in Mms2, a protein involved in Rad6-dependent postreplication DNA repair (PRR). The specificity of the mutator effect caused by ump1 is discussed in light of the proposed role of the proteasome activity in the regulation of the PRR mechanisms.     

Outbreak of Pseudomonas aeruginosa infections with PER-1 extended-spectrum beta-lactamase in Warsaw, Poland: further evidence for an international clonal complex

Forty-one Pseudomonas aeruginosa isolates with extended-spectrum beta-lactamases (ESBLs) from a hospital in Warsaw, Poland, were analyzed. Thirty-seven isolates from several wards were collected over 9 months in 2003 and 2004. The isolates were recovered from patients with multiple types of infections, mostly respiratory tract and postoperative wound infections. All 41 isolates produced the PER-1 ESBL, originally observed in Turkey but recently also identified in several countries in Europe and the Far East. The bla(PER-1) gene resided within the Tn1213 composite transposon, which was chromosomally located. Pulsed-field gel electrophoresis and multilocus sequence typing (MLST) revealed the presence of three separate clones among the isolates. Two of these, corresponding to sequence types (STs) ST244 and ST235, were responsible for parallel outbreaks. Apart from PER-1, all the isolates produced OXA-2 oxacillinase. ST235 isolates additionally expressed a novel enzyme, OXA-74, differing by one amino acid from the OXA-17 ESBL identified originally in PER-1- and OXA-2-positive P. aeruginosa isolates from Ankara, Turkey, in 1992. These earlier Ankara isolates with PER-1, OXA-2, and OXA-17 were also classified into ST235, which is a single-locus variant of two other STs, ST227 and ST230. ST227, ST230, and ST235 all correspond to the recently described clonal complex BG11, which seems to be internationally distributed, having spread in Turkey, Greece, Italy, Hungary, Poland, Sweden, and much of Russia. It is associated with various beta-lactamases, including PER-1 and VIM metalloenzymes. This work further demonstrates the value of MLST of P. aeruginosa.     

Serological and structural characterization of the O-antigens of the unclassified <Emphasis Type="Italic">Proteus mirabilis</Emphasis> strains TG 83, TG 319, and CCUG 10700 (OA)

INTRODUCTION: Lipopolysaccharide (endotoxin, LPS) is an important potential virulence factor of Proteus rods. The serological specificity of the bacteria is defined by the structure of the O-polysaccharide chain (O-antigen) of the LPS. Until now, 76 O-serogroups have been differentiated among Proteus strains. MATERIALS AND METHODS: LPSs were isolated from Proteus mirabilis TG 83, TG 319, and CCUG 10700 (OA) strains by phenol/water extraction. Antisera were raised by immunization of rabbits with heat-killed bacteria. Serological investigations were performed using enzyme immunosorbent assay, passive immunohemolysis, inhibition of both assays, absorption of antisera, and Western blot. RESULTS: The cross-reactive epitope shared by these strains and P. penner O72a,O72b is located on the O-polysaccharide and is most likely associated with an alpha-D-Glcp-(1-->6)-beta-D-GalpNAc disaccharide fragment. The serological data indicated the occurrence of two core types in the LPSs studied, one characteristic for P. mirabilis TG 319 and CCUG 10700 (OA) and the other for P. mirabilis TG 83 and O57. CONCLUSIONS: The serological and structural data showed that P. mirabilis TG 83, TG 319, CCUG 10700 (OA), and O57 have the same O-antigen structure and could be qualified to the Proteus O57 serogroup.