Replication of plasmids derived from Shiga toxinconverting bacteriophages in starved Escherichia coli

The pathogenicity of Shiga toxin-producing Escherichia coli (STEC) depends on the expression of stx genes that are located on lambdoid prophages. Effective toxin production occurs only after prophage induction, and one may presume that replication of the phage genome is important for an increase in the dosage of stx genes, positively influencing their expression. We investigated the replication of plasmids derived from Shiga toxin (Stx)-converting bacteriophages in starved E. coli cells, as starvation conditions may be common in the intestine of infected humans. We found that, unlike plasmids derived from bacteriophage lambda, the Shiga toxin phage-derived replicons did not replicate in amino acid-starved relA+ and relA” cells (showing the stringent and relaxed responses to starvation, respectively). The presence of the stable fraction of the replication initiator O protein was detected in all tested replicons. However, while ppGpp, the stringent response effector, inhibited the activities of the l PR promoter and its homologues from Shiga toxin-converting bacteriophages, these promoters, except for lambda PR, were only weakly stimulated by the DksA protein. We suggest that this less efficient (relative to lambda) positive regulation of transcription responsible for transcriptional activation of the origin contributes to the inhibition of DNA replication initiation of Shiga toxin-converting bacteriophages in starved host cells, even in the absence of ppGpp (as in starved relA” hosts). Possible clinical implications of these results are discussed

Photocatalytic Activity and Mechanical Properties of Cements Modified with TiO2/N

In this paper, studies of the mechanical properties and photocatalytic activity of new photoactive cement mortars are presented. The new building materials were obtained by the addition of 1, 3, and 5 wt % (based on the cement content) of nitrogen-modified titanium dioxide (TiO2/N) to the cement matrix. Photocatalytic active cement mortars were characterized by measuring the flexural and the compressive strength, the hydration heat, the zeta potential of the fresh state, and the initial and final setting time. Their photocatalytic activity was tested during NOx decomposition. The studies showed that TiO2/N gives the photoactivity of cement mortars during air purification with an additional positive effect on the mechanical properties of the hardened mortars. The addition of TiO2/N into the cement shortened the initial and final setting time, which was distinctly observed using 5 wt % of the photocatalyst in the cement matrix

The Role of Green Urban Wastelands in 3rd Place Creation. Challenge for Urban Policy in Poland

An Urban area is a complex system that constantly changes, forms dynamically and functionsindependently. Despite of huge development pressure coming from the fast urban growth there are still many neglected areas or so-called urban wastelands. These zones seem to be commonly considered (also by local governments and city planners) as worthless and unproductive critical spaces that need to be invested in and returned to the city. On the other hand, we ahould point out a growing conviction among scientists about the importance of wastelands in context of their strong impact on the urban ecosystem and some social aspects of urban life as well. (Gandy, 2013; Wysocki, Sikorski 2009). The urban wasteland is nowadays one of extremely few forms of informal green spaces that people can freely use according to their needs and ideas. These places don’t have any defined forms or functions, so they leave a space for their user’s creativity. Supposedly, they may take different forms from making grass roots to much more complex bottom up initiatives

The engine unit of a building machine

Tato práce se zabývá kolovými stavebními nakladači a jejich motorovou jednotkou. V první části je proveden stručný popis a rešeršní rozbor strojů zadaných technických parametrů, konstrukce jejich stavby, výkonu práce a způsobu řízení náprav. Dále je proveden výpočet celkového výkonu, který vychází ze součtu výkonů potřebných pro různé pracovní režimy nakladače. V poslední části je navrženo několik vhodných motorových jednotek z dostupných katalogů světových výrobců, které výkonově splňují výpočet a odpovídají parametrům zadání.This thesis is concerned about wheel building loaders and their engine unit. There is a brief description of machines fulfilling assignment parameters in the first part, including their construction, processing and steering solution. The following part consists of total power assessment. Total power is reached by addition of all needed power for various process modes. The last part deals with searching for suitable engine unit according to worldwide producer's catalogues.

Automatic Multiple Sensor Data Acquisition System in a Real-time Production Environment

AbstractThis paper presents a multiple sensor automatic data acquisition system deployed on a CNC turning center in a real- time production environment at Schivo Precision, Waterford, Ireland. The machine has been fitted with a variety of sensors measuring acoustic emission, cutting force & vibration installed at the turret of the machine, coupled with an automatic image acquisition system monitoring the wear on the tools in real time after each operation. The combination of sensors and data acquisition is novel in that it brings together all the currently popular sensoring techniques in the field of tool condition monitoring and tests the validity of these techniques in a live production environment. The sensor data acquisition and optical tool wear measurements are controlled by a computer automatically with no intervention from the machine tool operator in normal production on a variety of component geometries, materials and cutting inserts. All the acquired data is available on-line for the research partners in the various countries. Independent operator feedback on the performance of the process in terms of both product dimensional stability and machined surface stability is used for evaluation of the acquired data applicability for tool condition monitoring

Slaying the Dragon: Dances Created During the Time of the Pandemic

Regina Nejman’s paper details a dance artist’s negotiation of art-making in a global pandemic. It focuses on her improvisational dance films that were combined with live performance and animation in a gallery-like viewing environment. She situates herself among the many screendances and digital archives shared during NYC’s lockdown

Small and Smaller—sRNAs and MicroRNAs in the Regulation of Toxin Gene Expression in Prokaryotic Cells: A Mini-Review

Non-coding small RNAs (sRNAs) have been identified in the wide range of bacteria (also pathogenic species) and found to play an important role in the regulation of many processes, including toxin gene expression. The best characterized prokaryotic sRNAs regulate gene expression by base pairing with mRNA targets and fall into two broad classes: cis-encoded sRNAs (also called antisense RNA) and trans-acting sRNAs. Molecules from the second class are frequently considered as the most related to eukaryotic microRNAs. Interestingly, typical microRNA-size RNA molecules have also been reported in prokaryotic cells, although they have received little attention up to now. In this work we have collected information about all three types of small prokaryotic RNAs in the context of the regulation of toxin gene expression

The use of selected commercial molecular assays for the microbiological diagnosis of tuberculosis

Introduction: We performed a retrospective assessment of the AMPLICOR Mycobacterium tuberculosis (MTB) assay for the molecular diagnosis of tuberculosis based on our own determinations between 1999 and 2009 and a preliminary assessment of the Xpert MTB/RIF system, which we are currently using. Materials and methods: The study groups comprised 1875 samples (including 104 inhibited samples) and 213 samples, respectively. Results: The sensitivities of the AMPLICOR MTB and the Xpert MTB/RIF assays were 81.9% and 81.8%, respectively, and their specificities were 97.2% and 99.5%, respectively, versus culture on Loewenstein-Jensen medium. Both assays showed a considerable difference in sensitivity depending on whether the test samples were smear-positive (AFB+) or smearnegative (AFB–). The sensitivities of the AMPLICOR MTB and the Xpert MTB/RIF assays were 97.8% and 100.0%, respectively, for AFB+ samples and 58.1% and 50.0%, respectively, for AFB– samples. Conclusions: Our results confirm full usefulness of the Xpert MTB/RIF assay for routine diagnosis in the case of smearpositive clinical samples.Wstęp: W pracy, retrospektywnie oceniono test AMPLICOR Mycobacterium tuberculosis (MTB) w molekularnej diagnostyce gruźlicy, na podstawie własnych oznaczeń w latach 1999–2009 oraz wstępnie oceniono system Xpert MTB/RIF, który jest na bieżąco w użyciu. Materiał i metody: Grupy badane obejmowały odpowiednio 1875 próbek (w tym 104 reakcje zahamowane) i 213 próbek. Wyniki: Czułość testów AMPLICOR MTB i Xpert MTB/RIF oceniono na 81,9% i 81,8%, a swoistość wynosiła odpowiednio 97,2% i 99,5%, wobec hodowli na pożywce Loewensteina-Jensena. Obydwa testy wykazywały znaczącą różnicę w czułości, w zależności od tego czy badane próbki były dodatnie (AFB+) czy ujemne (AFB–) w rozmazie. I tak dla próbek AFB+ czułość wynosiła 97,8% i 100%, a dla próbek AFB– czułość była 58,1% i 50%, odpowiednio dla testów AMPLICOR MTB i Xpert MTB/RIF. Wnioski: Przedstawione wyniki wykazują pełną przydatność testu Xpert MTB/RIF w rutynowej diagnostyce dla próbek klinicznych, dodatnich w mikroskopowym badaniu rozmazu. Pneumonol. Alergol. Pol. 2012; 80, 1: 6–1