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871.
The atypical response regulator HP1021 controls formation of the Helicobacter pylori replication initiation complex
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Rafał Donczew Łukasz Makowski Paweł Jaworski Martyna Bezulska Małgorzata Nowaczyk Jolanta Zakrzewska‐Czerwińska Anna Zawilak‐Pawlik 《Molecular microbiology》2015,95(2):297-312
The replication of a bacterial chromosome is initiated by the DnaA protein, which binds to the specific chromosomal region oriC and unwinds duplex DNA within the DNA‐unwinding element (DUE). The initiation is tightly regulated by many factors, which control either DnaA or oriC activity and ensure that the chromosome is duplicated only when the conditions favor the survival of daughter cells. The factors controlling oriC activity often belong to the protein families of two‐component systems. Here, we found that Helicobacter pylori oriC activity is controlled by HP1021, a member of the atypical response regulator family. HP1021 protein specifically interacts with H. pylori oriC at HP1021 boxes (5′‐TGTT[TA]C[TA]‐3′), which overlap with three modules important for oriC function: DnaA boxes, the hypersensitivity (hs) region and the DUE. Consequently, HP1021 binding to oriC precludes DnaA‐oriC interactions and inhibits DNA unwinding at the DUE. Thus, HP1021 constitutes a negative regulator of the H. pylori orisome assembly in vitro. Furthermore, HP1021 boxes were found upstream of at least 70 genes, including those encoding CagA and Fur proteins. We postulate that HP1021 might coordinate chromosome replication, and thus bacterial growth, with other cellular processes and conditions in the human stomach. 相似文献
872.
In Poland Capercaillie (Tetrao urogallus L.) is one of the most seriously endangered grouse species. The ability of semen collection and its utilization for Capercaillie female insemination would allow overcoming some fertility problems observed in captive-bred populations and thus reduce the rate of loss of genetic diversity. The present experiment was carried out on 13 individuals: eight males were kept with females and five alone. From each male, semen was collected four times, every second day, and overall semen appearance (color, viscosity), ejaculate volume, spermatozoa concentration, motility and morphology were examined. Ejaculates suitable for artificial insemination (AI) were obtained from 11 individuals. The volume of ejaculates varied from one drop (noted as 0.010 ml) to 0.180 ml, whereas spermatozoa concentration varied from 100 × 10(6) ml(-1) to 1950 × 10(6) ml(-1). The total amount of live spermatozoa for males kept with females varied from 82.0 to 98.3% (92.9% on average) and among them, from 38.7 to 82.0% were morphologically normal (67.6% on average), whereas for solitary males these values were the following: from 93.7 to 98.7 of total live (96.3% on average) and from 45.0 to 85.3% live normal cells (65.7% on average). No significant group effect was observed for above traits. Semen from males kept with females contained significantly (P<0.01) fewer cells with bulb head (12.2% vs. 21.6%), but higher numbers of bent neck spermatozoa (3.0 vs. 2.1%) and with other deformities (10.0 vs. 6.8%); however, for last two forms existing differences were not significant. Results obtained indicate the possibility of collecting valuable ejaculates from captive-bred Capercaillie, both kept with or without females, which makes possible the application of AI in order to increase the progeny number and gene exchange of this species across time and geographical distance. 相似文献
873.
7-day soil drought followed by 7-day rehydration was applied to potted German chamomile (Chamomilla recutita) plants at the beginning of their generative stage. Plants of a wild type (WT), plus two diploid (2n) and two tetraploid
(4n) genotypes were studied, in order to examine the alterations in chlorophyll (Chl) and carotenoids (Car) contents, and
chlorophyll fluorescence (CF) parameters during water shortage and rehydration. The fresh mass of the anthodia after the recovery
was also studied. 相似文献
874.
Łukasz Kruszyna Margarita Lianeri Błażej Rubis Hanna Knuła Maria Rybczyńska Sylwia Grodecka-Gazdecka Paweł P. Jagodziński 《Molecular biology reports》2011,38(2):1263-1267
The contribution of the CCL2 −2518 A>G (rs 1024611) polymorphism in the occurrence and progression of various cancers has been found to be discordant.
We studied the prevalence of the CCL2 −2518 A>G polymorphism in patients with breast cancer (n = 160) and controls (n = 323) in a sample of the Polish population.
There were no significant differences in CCL2 −2518 A>G genotypes between patients with breast tumors and controls. Odds ratio (OR) for patients bearing the GG genotype
was 1.481 (95% CI = 0.7711–2.845, P = 0.2358), and OR of the GG and AG genotypes was 0.7269 (95% CI = 0.4967–1.064, P = 0.1002). There was also no significant distinction in the prevalence of alleles between patients and healthy individuals.
OR for the CCL2 −2518 G allele frequency was 0.8903 (95% CI = 0.6611–1.199, P = 0.4441). Analysis of the association between tumor size, lymph node metastases, histological grade, and distribution of
genotypes and alleles for the CCL2 −2518 A>G polymorphism also did not show significant differences. Our results did not show association of the CCL2 −2518 A>G polymorphism with breast cancer occurrence and clinical characteristics in a sample of the Polish cohort. 相似文献
875.
The effect of 2–48 h treatment of Lupinus angustifolius L. roots with lead nitrate at the concentration of 10−4 M on the nucleoli in meristematic cells was investigated. In the lead presence the number of ring-shaped as well as segregated
nucleoli increased especially after 12–48 h of treatment, while spindle-shaped nucleoli appeared after 24 h and 48 h. Lead
presence also increased the frequency of cells with silver-stained particles in the nucleus and the number of these particles
especially from the 12th hour of treatment. It was accompanied by significant decline of nucleolar area. Analysis of these
cells in transmission electron microscope confirmed the presence of ring-shaped and segregated nucleoli. Moreover, electron
microscopy revealed compact structure nucleoli without granular component. Additionally, one to three oval-shaped fibrillar
structures attached to nucleolus or lying free in the nucleoplasm were visible. The possible mechanism of lead toxicity to
the nucleolus is briefly discussed. 相似文献
876.
GRZEGORZ NIEDŹWIEDZKI PRZEMYSŁAW GORZELAK TOMASZ SULEJ 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2011,44(1):87-92
Nied?wiedzki, G., Gorzelak, P. & Sulej, T. 2010: Bite traces on dicynodont bones and the early evolution of large terrestrial predators. Lethaia, Vol. 44, pp. 87–92. Dicynodont (Synapsida: Anomodontia) bones from the Late Triassic (late Norian/early Rhaetian) of Poland yield characteristic tooth marks that can be attributed to three ichnotaxa (Linichnus serratus, Knethichnus parallelum and Nihilichnus nihilicus). The general shape and dimension of these traces perfectly match the dental morphology of a co‐occurring carnivorous dinosaur. It is therefore concluded that early carnivorous dinosaurs were feeding on dicynodonts. This discovery constitutes one of the oldest evidence of dinosaur predator–prey interaction. It is suggested that an evolutionary increase in the size of dicynodonts across the Late Triassic may have been driven by selection pressure to reach a size refuge from early dinosaur predators. □Bite traces, dicynodonts, dinosaurs, predation, Triassic. 相似文献
877.
Contactins are modular extracellular cell matrix proteins that are present in the brain, and they are responsible for the
proper development and functioning of neurons. They contain six immunoglobulin-like IgC2 domains and four fibronectin type
III repeats. The interactions of contactin with other proteins are poorly understood. The mechanical properties of all IgC2
domains of human contactin 4 were studied using a steered molecular dynamics approach and CHARMM force field with an explicit
TIP3P water environment on a 10-ns timescale. Force spectra of all domains were determined computationally and the nanomechanical
unfolding process is described. The domains show different mechanical stabilities. The calculated maxima of the unfolding
force are in the range of 900–1700 pN at a loading rate of 7 N/s. Our data indicate that critical regions of IgC2 domains
2 and 3, which are responsible for interactions with tyrosine phosphatases and are important in nervous system development,
are affected by even weak mechanical stretching. Thus, tensions present in the cell may modulate cellular activities related
to contactin function. The present data should facilitate the interpretation of atomic force microscope single-molecule spectra
of numerous proteins with similar IgC2 motives. 相似文献
878.
BOGUSŁAW KOŁODZIEJ STJEPKO GOLUBIC IOAN I. BUCUR GUDRUN RADTKE ALINE TRIBOLLET 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2012,45(1):34-45
Ko?odziej, B., Golubic, S., Bucur, I.I., Radtke, G. & Tribollet, A. 2011: Early Cretaceous record of microboring organisms in skeletons of growing corals. Lethaia, Vol. 45, pp. 34–45. A spectacularly preserved assemblage of microbial euendoliths, penetrating into skeletons of growing scleractinian corals, has been recognized in Early Aptian (Early Cretaceous) reef limestone of the Rar?u Mountains (East Carpathians, NE Romania). Microboring euendolithic filaments were found in five coral colonies of the suborder Microsolenina. They remained in part well‐preserved, often impregnated with iron oxides, which made them visible even in strongly recrystallized parts of coral skeletons. Filaments of a wide range of sizes (2–40 μm in diameter) were concentrated within medium parts of coral septa, oriented along the septa in the direction of the coral growth. The larger filaments were tubular, occurring in bundles and branched into finer, often tapering branches. Their behaviour and organization were quite similar to the modern euendolithic siphonalean chlorophyte Ostreobium. Filament diameters exceeded those reported for the modern species, but covered a similarly wide size range. Narrower frequently branching filaments, 4–8 μm in diameter, resemble distal branching patterns of modern Ostreobium quekettii. Some very thin filaments (ca. 1–2 μm) observed within skeleton or inside the large tubular filaments, sometimes associated with globular swellings, may represent euendolithic fungi. The recrystallization of coral skeleton had limited effect on preservation of euendoliths due to their impregnation with iron oxides; microbial euendoliths were subjected to different taphonomic changes. □Chlorophytes, Early Cretaceous, fungi, microbial euendoliths, Romania, scleractinian corals. 相似文献
879.
Minarowska A Minarowski Ł Karwowska A Milewska AJ Gacko M 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2012,50(1):20-24
Increased tissue activity of cathepsin A and cathepsin C can be observed in many pathological conditions. It is associated with an enhanced degradation of glycosaminoglycans, proteoglycans, and glycoproteins, and results in their decreased tissue content. Cathepsin C releases the glycosidases from complexes formed with cathepsin A, and reinstates their activity. In this review a current state of knowledge is presented concerning the regulation of selected glycosidases activity by cathepsin A (EC 3.4.16.1) and C (EC 3.4.14.1). 相似文献
880.
Łabanowska M Filek M Kościelniak J Kurdziel M Kuliś E Hartikainen H 《Journal of plant physiology》2012,169(3):275-284
Biochemical analyses of antioxidant content were compared with measurements of fluorescence and electron paramagnetic resonance (EPR) to examine the alteration of radicals in wheat seedlings exposed to 2 days of selenium stress. Two genotypes of Polish and one of Finnish wheat, differing in their tolerance to long-term stress treatment, were cultured under hydroponic conditions to achieve the phase of 3-leave seedlings. Afterwards, selenium (sodium selenate, 100 μM concentration) was added to the media. After Se-treatment, all varieties showed an increase in carbohydrates (soluble and starch), ascorbate and glutathione content in comparison to non-stressed plants. These changes were more visible in Finnish wheat. On the basis of lipid peroxidation measurements, Finnish wheat was recognized as the genotype more sensitive to short-term Se-stress than the Polish varieties. The antioxidant enzyme activities (superoxide dismutase, ascorbate peroxidase and glutathione reductase) increased in Polish genotypes, whereas they decreased in Finnish wheat plants cultured on Se media. The action of reactive oxygen species in short-term action of Se stress was confirmed by the reduction of PSII and PSI system activities (measured by fluorescence parameters and EPR, respectively). EPR studies showed changes in redox status (especially connected with Mn(II)/Mn(III), and semiquinone/quinone ratios) in wheat cell after Se treatment. The involvement of the carbohydrate molecules as electron traps in production of long-lived radicals is postulated. 相似文献