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941.
I. Jana I. Janssen Jürgen Krücken Janina Demeler Marta Basiaga S?awomir Korna? Georg von Samson-Himmelstjerna 《PloS one》2013,8(4)
Macrocyclic lactones (MLs) represent the major drug class for control of parasitic infections in humans and animals. However, recently reports of treatment failures became more frequent. In addition to human and ruminant parasitic nematodes this also is the case for the horse-nematode Parascaris equorum. Nevertheless, to date the molecular basis of ML resistance is still not understood. Unspecific resistance mechanisms involving transporters such as P-glycoproteins (Pgps) are expected to contribute to ML resistance in nematodes. Here, complete sequences of two P. equorum Pgps were cloned and identified as orthologs of Caenorhabditis elegans Ppg-11 and an unnamed Caenorhabditis briggsae Pgp designated as Pgp-16 using phylogenetic analysis. Quantitative real-time PCR was used to compare expression between tissues. Significantly higher PeqPgp-11 expression was found in the gut for both genders, whereas for PeqPgp-16 the body wall was identified as predominant expression site. Furthermore, Pgps were analyzed regarding their participation in resistance development. Using SeqDoC analyses, Pgp-sequences of P. equorum populations with different ML susceptibility were compared. This approach revealed three single nucleotide polymorphisms (SNPs) causing missense mutations in the PeqPgp-11 sequence which correlated with decreased ML susceptibility. However, no resistance associated differences in mRNA expression levels were detected between embryonated eggs of these populations. In contrast, comparison of two pre-adult groups with different ivermectin (IVM) susceptibility revealed the presence of the three SNPs and in addition statistically significant PeqPgp-11 overexpression in the group of worms with reduced susceptibility. These results indicate that Pgp-11 might be involved in IVM resistance in P. equorum as it shows increased expression in an IVM exposed life-cycle stage of an IVM resistant population as well as occurrence of putatively resistance associated SNPs in populations with reduced IVM susceptibility. These SNPs are promising diagnostic candidates for detection of ML resistance with potential also for other parasitic nematode species. 相似文献
942.
Veronika Zelinová Ľubica Halušková Jana Huttová Peter Illéš Igor Mistrík Katarína Valentovičová Ladislav Tamás 《Protoplasma》2011,248(3):523-530
The short-term exposure of barley roots to low Al concentration caused significant root growth inhibition and radial swelling of roots. During Al treatment, the radial expansion of root cells occurred in root tissues representing elongation zone and meristem. Both low pH and Al treatments caused significant disruption of cell membranes in swollen roots. In contrast to Evans blue uptake callose formation was observed only at higher Al concentrations and was detected in both swollen and adjacent root areas. Similarly to Al, exogenous short-term application of indole-3-acetic acid, polar transport inhibitor triiodobenzoic acid, ethylene precursor 1-aminocyclopropane-1-carboxylic acid or H2O2 evoked root growth inhibition and radial cell expansion in barley root tip too. 相似文献
943.
944.
Probing the Diameter Limit of Single Walled Carbon Nanotubes in SWCNT: Fullerene Solar Cells 下载免费PDF全文
Moritz Pfohl Konstantin Glaser Arko Graf Adrian Mertens Daniel D. Tune Tanja Puerckhauer Asiful Alam Li Wei Yuan Chen Jana Zaumseil Alexander Colsmann Ralph Krupke Benjamin S. Flavel 《Liver Transplantation》2016,6(21)
In this work, for the first time, the diameter limit of surfactant wrapped single walled carbon nanotubes (SWCNTs) in SWCNT:C60 solar cells is determined through preparation of monochiral small and large diameter nanotube devices as well as those from polychiral mixtures. Through assignment of the different nanotube chiralities by photoluminescence and optical density measurements a diameter limit yielding 0% internal quantum efficiency (IQE) is determined. This work provides insights into the required net driving energy for SWCNT exciton dissociation onto C60 and establishes a family of (n,m) species which can efficiently be utilized in polymer‐free SWCNT:C60 solar cells. Using this approach the largest diameter nanotube with an IQE > 0% is found to be (8,6) with a diameter of 0.95 nm. Possible strategies to extend this diameter limit are then discussed. 相似文献
945.
946.
Veronika Zelinová Aster Alemayehu Beáta Bočová Jana Huttová Igor Mistrík Ladislav Tamás 《Acta Physiologiae Plantarum》2014,36(11):2935-2946
Short-term exposure (15 min) of barley roots to different chemical elements revealed that Cd, Cu, Hg and Pb were the most toxic ones causing a marked root growth inhibition even at µM concentrations. Gd, La, Al, Cr, As, Zn, Ni and Se inhibited root growth to a similar extent only at mM concentrations. Despite the high 20 mM concentration, Co caused only a slight, while Mn, Mg or Ca did not evoke any root growth inhibition. Elements at concentrations inhibiting root growth caused a considerable accumulation of indole-3-acetic acid in the root apex. While Cr, As and Zn inhibited, Cd, Cu, Hg, Pb, Gd, La and Al markedly stimulated the generation of reactive oxygen species in the beginning of differentiation zone. Auxin signalling inhibitor alleviated or prevented root growth inhibition, reactive oxygen species generation and the stimulation of lipoxygenase and glutathione peroxidase activity by various elements, indicating a key role of auxin signalling in the stress response of barley root tip. On the other hand, it did not affect or even had an additive effect on dehydroascorbate reductase and ascorbic acid oxidase activity in combination with different elements. Our results indicate that the primary response of barley roots to the presence of various chemical elements during the short-term treatment is not a specific but rather a general adaptive stress response enabling the plant to survive adverse conditions. 相似文献
947.
Alexander M. Cardoso Janaína J. V. Cavalcante Maurício E. Cant?o Claudia E. Thompson Roberto B. Flatschart Arnaldo Glogauer Sandra M. N. Scapin Youssef B. Sade Paulo J. M. S. I. Beltr?o Alexandra L. Gerber Orlando B. Martins Eloi S. Garcia Wanderley de Souza Ana Tereza R. Vasconcelos 《PloS one》2012,7(11)
The shortage of petroleum reserves and the increase in CO2 emissions have raised global concerns and highlighted the importance of adopting sustainable energy sources. Second-generation ethanol made from lignocellulosic materials is considered to be one of the most promising fuels for vehicles. The giant snail Achatina fulica is an agricultural pest whose biotechnological potential has been largely untested. Here, the composition of the microbial population within the crop of this invasive land snail, as well as key genes involved in various biochemical pathways, have been explored for the first time. In a high-throughput approach, 318 Mbp of 454-Titanium shotgun metagenomic sequencing data were obtained. The predominant bacterial phylum found was Proteobacteria, followed by Bacteroidetes and Firmicutes. Viruses, Fungi, and Archaea were present to lesser extents. The functional analysis reveals a variety of microbial genes that could assist the host in the degradation of recalcitrant lignocellulose, detoxification of xenobiotics, and synthesis of essential amino acids and vitamins, contributing to the adaptability and wide-ranging diet of this snail. More than 2,700 genes encoding glycoside hydrolase (GH) domains and carbohydrate-binding modules were detected. When we compared GH profiles, we found an abundance of sequences coding for oligosaccharide-degrading enzymes (36%), very similar to those from wallabies and giant pandas, as well as many novel cellulase and hemicellulase coding sequences, which points to this model as a remarkable potential source of enzymes for the biofuel industry. Furthermore, this work is a major step toward the understanding of the unique genetic profile of the land snail holobiont. 相似文献
948.
María Prez‐Burgos Inmaculada García‐Romero Jana Jung Miguel A. Valvano Lotte Sgaard‐Andersen 《Molecular microbiology》2019,112(4):1178-1198
Myxococcus xanthus is a model bacterium to study social behavior. At the cellular level, the different social behaviors of M. xanthus involve extensive cell–cell contacts. Here, we used bioinformatics, genetics, heterologous expression and biochemical experiments to identify and characterize the key enzymes in M. xanthus implicated in O‐antigen and lipopolysaccharide (LPS) biosynthesis and examined the role of LPS O‐antigen in M. xanthus social behaviors. We identified WbaPMx (MXAN_2922) as the polyisoprenyl‐phosphate hexose‐1‐phosphate transferase responsible for priming O‐antigen synthesis. In heterologous expression experiments, WbaPMx complemented a Salmonella enterica mutant lacking the endogenous WbaP that primes O‐antigen synthesis, indicating that WbaPMx transfers galactose‐1‐P to undecaprenyl‐phosphate. We also identified WaaLMx (MXAN_2919), as the O‐antigen ligase that joins O‐antigen to lipid A‐core. Our data also support the previous suggestion that WzmMx (MXAN_4622) and WztMx (MXAN_4623) form the Wzm/Wzt ABC transporter. We show that mutations that block different steps in LPS O‐antigen synthesis can cause pleiotropic phenotypes. Also, using a wbaPMx deletion mutant, we revisited the role of LPS O‐antigen and demonstrate that it is important for gliding motility, conditionally important for type IV pili‐dependent motility and required to complete the developmental program leading to the formation of spore‐filled fruiting bodies. 相似文献
949.
Yuzenkova J Nechaev S Berlin J Rogulja D Kuznedelov K Inman R Mushegian A Severinov K 《Journal of molecular biology》2003,330(4):735-748
Xp10 is a lytic bacteriophage of the phytopathogenic bacterium Xanthomonas oryzae. Though morphologically Xp10 belongs to the Syphoviridae family, it encodes its own single-subunit RNA polymerase characteristic of T7-like phages of the Podoviridae family. Here, we report the determination and analysis of the 44,373 bp sequence of the Xp10 genome. The genome is a linear, double-stranded DNA molecule with 3' cohesive overhangs and no terminal repeats or redundancies. Half of the Xp10 genome contains genes coding for structural proteins and host lysis functions in an arrangement typical for temperate dairy phages that are related to the Escherichia coli lambda phage. The other half of the Xp10 genome contains genes coding for factors of host gene expression shut-off, enzymes of viral genome replication and expression. The two groups of genes are transcribed divergently and separated by a regulatory region, which contains divergent promoters recognized by the host RNA polymerase. Xp10 has apparently arisen through a recombination between genomes of widely different phages. Further evidence of extensive gene flux in the evolution of Xp10 includes a high fraction (10%) of genes derived from an HNH-family endonuclease, and a DNA-dependent DNA polymerase that is closer to a homolog from Leishmania than to DNA polymerases from other phages or bacteria. 相似文献