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31.
32.
Directionality of lambda plasmid DNA replication carried out by the heritable replication complex 下载免费PDF全文
There are two ‘pathways’ of replication of λ plasmids in Escherichia coli. One pathway requires the assembly of a new replication complex before replication and the second pathway is based on the activity of the replication complex inherited by one of two daughter plasmid copies after a preceding replication round. Such a phenomenon was postulated to occur also in other replicons, including Saccharomyces cerevisiae autonomously replicating sequences. Here we investigated directionality of λ plasmid replication carried out by the heritable and newly assembled replication complexes. Using two-dimensional agarose gel electrophoresis and electron microscopy we demonstrated that in both normal growth conditions and during the relaxed response to amino acid starvation (when only replication carried out by the heritable complex is possible), bidirectionally and undirectionally replicating plasmid molecules occurred in host cells in roughly equal proportions. The results are compatible with the hypothesis that both complexes (heritable and newly assembled) are equivalent. 相似文献
33.
Koteja J Pyka-Fościak G Vogelgesang M Szklarzewicz T 《Arthropod Structure & Development》2003,32(2-3):247-256
The paired ovaries of Steingelia gorodetskia are composed of about 100 telotrophic ovarioles devoid of terminal filaments (scale insect autapomorphy). In structure they resemble those of other scale insects, but differ in the following details: (a) all ovarioles develop synchronously, (b) they are suspended to the lateral oviducts by means of long stalks, (c) the tropharium is tubular (unique in scale insects) and (d) consists of 15-35, trophocytes, 2-4 previtellogenic oocytes that further develop, and numerous somatic prefollicular cells, (e) the vitellarium houses 2-4 linearly arranged vitellarial oocytes (versus one in most scale insects). Most of these features must be considered as plesiomorphic corresponding with the conditions in the most primitive Heteroptera. Bacterial endosymbionts have been found in some somatic cells, trophocytes, oocytes and in the nutritive cord. Present results support the opinion, based on external morphology, that the Steingeliidae are closely related to the Ortheziidae, Xylococcidae and Matsucoccidae. 相似文献
34.
Goslinski T Wenska G Golankiewicz B Balzarini J De Clercq E 《Nucleosides, nucleotides & nucleic acids》2003,22(5-8):911-914
Tricyclic (T) analogues of acyclovir (ACV, 1) and ganciclovir (GCV, 2) carrying the 3,9-dihydro-9-oxo-5H-imidazo[1,2-a]purine system [i.e., 6-(4-BrPh)TACV, 5 and 6-(4-BrPh)TGCV, 6] were transformed into 6-[(4'-R2)-4-biphenylyl] derivatives of TACV (7-9) and TGCV (10-12) by Suzuki cross coupling with 4-substituted phenylboronic acids. Compound 11 (R2 = CH2OH) showed a high (approximately 1000) selectivity index against herpes simplex virus type 1 (HSV-1) together with advantageous fluorescence properties (emission in visible region, little overlap with absorption and moderate intensity). 相似文献
35.
Cheung AW Danho W Swistok J Qi L Kurylko G Rowan K Yeon M Franco L Chu XJ Chen L Yagaloff K 《Bioorganic & medicinal chemistry letters》2003,13(1):133-137
Systematic substitution of His(6) residue using non-selective hMC4R pentapeptide agonist (Bu-His(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2)) as the template led to the identification of Bu-Atc(6)(2-aminotetraline-2-carboxylic acid)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) which showed moderate selectivity towards hMC4R over hMC1R. Further SAR studies resulted in the discovery of Penta-5-BrAtc(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) and Penta-5-Me(2)NAtc(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) which are potent hMC4R agonists and are inactive in hMC1R, hMC3R and hMC5R agonist assays. 相似文献
36.
Wegrowski Y Gillery P Kotlarz G Perreau C Georges N Maquart FX 《Molecular and cellular biochemistry》2000,205(1-2):125-131
Cell culture in collagen lattice is known to be a more physiological model than monolayer for studying the regulation of extracellular matrix protein deposition. The synthesis of sulfated glycosaminoglycans (GAG) and dermatan sulfate (DS) proteoglycans by 3 cell strains were studied in confluent monolayers grown on plastic surface, in comparison to fully retracted collagen lattices. Cells were labelled with35S-sulfate, followed by GAG and proteoglycan analysis by cellulose acetate and SDS-polyacrylamide gel electrophoresis, respectively. The 3 cell strains contracted the lattice in a similar way. In monolayer cultures, the major part of GAG was secreted into culture medium whereas in lattice cultures of dermal fibroblasts and osteosarcoma MG-63 cells but not fibrosarcoma HT-1080 cells, a higher proportion of GAGs, including dermatan sulfate, was retained within the lattices. Small DS proteoglycans, decorin and biglycan, were detected in fibroblasts and MG-63 cultures. They were preferentially trapped within the collagen gel. In retracted lattices, decorin had a higher Mr than in monolayer. Biglycan was detected in monolayer and lattice cultures of MG-63 cells but in lattice cultures only in the case of fibroblasts. In this last case, an up regulation of biglycan mRNA steady state level and down regulation of decorin mRNA was observed, in comparison to monolayers, indicating that collagen can modulate the phenotypical expression of small proteoglycan genes.Supported by a fellowship from the Centre National de la Recherche Scientifique 相似文献
37.
Bialek-Bylka Grazyna E. Fujii Ritsuko Chen Chun-Hai Oh-oka Hirozo Kamiesu Akihisa Satoh Kazuhiko Koike Hiroyuki Koyama Yasushi 《Photosynthesis research》1998,58(2):135-142
Carotenoids were extracted, at 4 °C in complete darkness and under nitrogen atmosphere, from the reaction center (RC) of a green-sulfur bacterium and the Photosystem (PS) I RC of a cyanobacterium; each extract was subjected to high-performance liquid chromatography (HPLC) using an apparatus equipped with a two-dimensional diode-array detector in order to spectroscopically identify cis–trans carotenoids while performing HPLC analysis. In the extract from the RC of Chlorobium tepidum, 15-cis and all-trans--carotenes as well as 13-cis-, 15-cis- and all- trans-chlorobactenes (in the order of elution) were identified, whereas in the extract from the PS I RC of Synechococcus vulcanus, 15-cis-, all-trans- and 9-cis--carotenes were found. Thus, the universal presence of 15- cis carotenoids in the 'iron sulfur-type' RCs has been shown in addition to the previous cases of the 'quinone-type' RCs. 相似文献
38.
Katarzyna Danis-Wlodarczyk Tomasz Olszak Michal Arabski Slawomir Wasik Grazyna Majkowska-Skrobek Daria Augustyniak Grzegorz Gula Yves Briers Ho Bin Jang Dieter Vandenheuvel Katarzyna Anna Duda Rob Lavigne Zuzanna Drulis-Kawa 《PloS one》2015,10(5)
We here describe two novel lytic phages, KT28 and KTN6, infecting Pseudomonas aeruginosa, isolated from a sewage sample from an irrigated field near Wroclaw, in Poland. Both viruses show characteristic features of Pbunalikevirus genus within the Myoviridae family with respect to shape and size of head/tail, as well as LPS host receptor recognition. Genome analysis confirmed the similarity to other PB1-related phages, ranging between 48 and 96%. Pseudomonas phage KT28 has a genome size of 66,381 bp and KTN6 of 65,994 bp. The latent period, burst size, stability and host range was determined for both viruses under standard laboratory conditions. Biofilm eradication efficacy was tested on peg-lid plate assay and PET membrane surface. Significant reduction of colony forming units was observed (70-90%) in 24 h to 72 h old Pseudomonas aeruginosa PAO1 biofilm cultures for both phages. Furthermore, a pyocyanin and pyoverdin reduction tests reveal that tested phages lowers the amount of both secreted dyes in 48-72 h old biofilms. Diffusion and goniometry experiments revealed the increase of diffusion rate through the biofilm matrix after phage application. These characteristics indicate these phages could be used to prevent Pseudomonas aeruginosa infections and biofilm formation. It was also shown, that PB1-related phage treatment of biofilm caused the emergence of stable phage-resistant mutants growing as small colony variants. 相似文献
39.
Młynarczyk A Szymanek-Majchrzak K Młynarczyk G 《Medycyna do?wiadczalna i mikrobiologia》2010,62(4):289-295
Fifty MRSA strains originated from clinical specimens were examined by the PCR method, for the presence of three genes: aacA-aphD, aadD oraz aph(3")-IIIa. The obtained results were correlated with the susceptibility of the strains to gentamicin, tobramicin, kanamicin, neomicin, amikacin and netilmicin. The susceptibility results were interpreted according with CLSI and EUCAST guidelines. aacA-aphD gene was found in 34 strains, aadD in 27 strains and aph(3")-IIIa was present in 22 strains. In 19 strains (38%) was present one of the investigated genes, in 29 (58%) strains two genes and in two strains (4%) all three genes were found. The most frequent variant was combination of aacA-aphD and aadD genes. 相似文献
40.
A C Frantz A D McDevitt L C Pope J Kochan J Davison C F Clements M Elmeros G Molina-Vacas A Ruiz-Gonzalez A Balestrieri K Van Den Berge P Breyne E Do Linh San E O ?gren F Suchentrunk L Schley R Kowalczyk B I Kostka D ?irovi? N ?prem M Colyn M Ghirardi V Racheva C Braun R Oliveira J Lanszki A Stubbe M Stubbe N Stier T Burke 《Heredity》2014,113(5):443-453
Although the phylogeography of European mammals has been extensively investigated
since the 1990s, many studies were limited in terms of sampling distribution, the
number of molecular markers used and the analytical techniques employed, frequently
leading to incomplete postglacial recolonisation scenarios. The broad-scale genetic
structure of the European badger (Meles meles) is of interest as it may
result from historic restriction to glacial refugia and/or recent anthropogenic
impact. However, previous studies were based mostly on samples from western Europe,
making it difficult to draw robust conclusions about the location of refugia,
patterns of postglacial expansion and recent demography. In the present study,
continent-wide sampling and analyses with multiple markers provided evidence for two
glacial refugia (Iberia and southeast Europe) that contributed to the genetic
variation observed in badgers in Europe today. Approximate Bayesian computation
provided support for a colonisation of Scandinavia from both Iberian and southeastern
refugia. In the whole of Europe, we observed a decline in genetic diversity with
increasing latitude, suggesting that the reduced diversity in the peripheral
populations resulted from a postglacial expansion processes. Although MSVAR v.1.3
also provided evidence for recent genetic bottlenecks in some of these peripheral
populations, the simulations performed to estimate the method''s power to
correctly infer the past demography of our empirical populations suggested that the
timing and severity of bottlenecks could not be established with certainty. We urge
caution against trying to relate demographic declines inferred using MSVAR with
particular historic or climatological events. 相似文献