Molecular genetic investigations on Balantidium ctenopharyngodoni Chen, 1955, a parasite of the grass carp (Ctenopharyngodon idella)

Balantidium ctenopharyngodoni is a common ciliate in Hungary, infecting the hindgut of grass carp (Ctenopharyngodon idella), a cyprinid fish of Chinese origin. Although data have already been presented on its occasional pathogenic effect on the endothelium of the host, generally it is a harmless inhabitant of the gut. Phylogenetic analysis of the 18S rDNA and ITS fragments of this protozoan proved that it is in the closest phylogenetic relationship with endocommensalist and symbiont ciliates of mammals feeding on large volumes of green forage, in a similar way as Balantidium spp. known from algae-eating marine fishes

Predictive Model for the Electrical Transport within Nanowire Networks

Thin networks of high aspect ratio conductive nanowires can combine high electrical conductivity with excellent optical transparency, which has led to a widespread use of nanowires in transparent electrodes, transistors, sensors, and flexible and stretchable conductors. Although the material and application aspects of conductive nanowire films have been thoroughly explored, there is still no model which can relate fundamental physical quantities, like wire resistance, contact resistance, and nanowire density, to the sheet resistance of the film. Here, we derive an analytical model for the electrical conduction within nanowire networks based on an analysis of the parallel resistor network. The model captures the transport characteristics and fits a wide range of experimental data, allowing for the determination of physical parameters and performance-limiting factors, in sharp contrast to the commonly employed percolation theory. The model thus constitutes a useful tool with predictive power for the evaluation and optimization of nanowire networks in various applications

Covalently Immobilized Lipases are Efficient Stereoselective Catalysts for the Kinetic Resolution of rac-(5-Phenylfuran-2-yl)-beta-alanine Ethyl Ester Hydrochlorides

Lipase-catalyzed enzymatic resolution of several new, exotic and variously substituted rac-(5-phenylfuran-2-yl)-beta-alanine ethyl esters was investigated. Given the structural instability of unsubstituted rac-(5-phenylfuran-2-yl)-beta-alanine ethyl ester, we used the stable hydrochloride salt of this rac-heteroaryl-3-aminopropanoic acid ethyl ester as potential substrate to increase the scope of the reaction. Optimization experiments revealed an efficient procedure for both analytical-and preparative-scale (S)-selective hydrolysis of several racemic beta-amino ester hydrochlorides in NH4OAc buffer (20 mM, pH 5.8) at 30 degrees C. Enzymatic resolutions were performed with covalently bound lipase AK from Pseudomonas fluorescens and lipase PS from Burkholderia cepacia on Immobead T2-150 as catalyst. Seven out of eight new resolution products were successfully isolated and appropriately characterized

Aptamer Conformational Change Enables Serotonin Biosensing with Nanopipettes

We report artificial nanopores in the form of quartz nanopipettes with ca. 10 nm orifices functionalized with molecular recognition elements termed aptamers that reversibly recognize serotonin with high specificity and selectivity. Nanoscale confinement of ion fluxes, analyte-specific aptamer conformational changes, and related surface charge variations enable serotonin sensing. We demonstrate detection of physiologically relevant serotonin amounts in complex environments such as neurobasal media, in which neurons are cultured in vitro. In addition to sensing in physiologically relevant matrices with high sensitivity (picomolar detection limits), we interrogate the detection mechanism via complementary techniques such as quartz crystal microbalance with dissipation monitoring and electrochemical impedance spectroscopy. Moreover, we provide a novel theoretical model for structure-switching aptamer-modified nanopipette systems that supports experimental findings. Validation of specific and selective small-molecule detection, in parallel with mechanistic investigations, demonstrates the potential of conformationally changing aptamer-modified nanopipettes as rapid, label-free, and translatable nanotools for diverse biological systems.ISSN:1520-6882ISSN:0003-270

Force-Controlled Formation of Dynamic Nanopores for Single-Biomolecule Sensing and Single-Cell Secretomics

Nanopore sensing of single nucleotides has emerged as a promising single-molecule technology for DNA sequencing and proteomics. Despite the conceptual simplicity of nanopores, adoption of this technology for practical applications has been limited by a lack of pore size adjustability and an inability to perform long-term recordings in complex solutions. Here we introduce a method for fast and precise on-demand formation of a nanopore with controllable size between 2 and 20 nm through force-controlled adjustment of the nanospace formed between the opening of a microfluidic device (made of silicon nitride) and a soft polymeric substrate. The introduced nanopore system enables stable measurements at arbitrary locations. By accurately positioning the nanopore in the proximity of single neurons and continuously recording single-molecule translations over several hours, we have demonstrated this is a powerful approach for single-cell proteomics and secretomics.ISSN:1936-0851ISSN:1936-086

Parental genetic diversity of brown trout (Salmo trutta m. fario) brood stock affects offspring susceptibility to whirling disease

Abstract Background Whirling disease, caused by the myxozoan parasite Myxobolus cerebralis, has high economical and ecological importance worldwide. Susceptibility to the disease varies considerably among salmonid species. In brown trout (Salmo trutta) the infection is usually subclinical with low mortality, which increases the risk of parasite dissemination, especially when farm fish are used for stocking natural habitats. The influence of intraspecific genetic differences (especially the level of homozygosity) on susceptibility is unknown. Therefore, we examined the possible correlations between parental genetic diversity and offspring susceptibility of brown trout stocks to whirling disease. Methods Two brown trout brood stocks from a German and a Hungarian fish farm were genetically characterized using microsatellite and lineage-specific genetic markers. The individual inbreeding coefficient f and pairwise relatedness factor r were estimated based on eight microsatellite markers. Brood stock populations were divided into groups according to low and high f and r value estimates and subjected to selective fertilization. The offspring from these separate groups were exposed to M. cerebralis actinospores, and the infection prevalence and intensity was measured and statistically analysed. Results The analysis of phylogeographic lineage heritage revealed high heterogeneity in the Hungarian brood stock since > 50% of individuals were Atlantic-Danubian hybrids, while only pure Atlantic-descending specimens were detected in the German population. Based on f msat and r msat estimations, classified non-inbred (NIB), inbred (IB) and a group of closely related fish (REL) were created. The susceptibility of their offspring varied considerably. Although there was no significant difference in the prevalence of M. cerebralis infection, the mean intensity of infection differed significantly between NIB and IB groups. In REL and IB groups, a high variability was observed in infection intensity. No external clinical signs were observed in the exposed brown trout groups. Conclusions Our findings indicate that the allelic diversity of brown trout brood stock may constitute a significant factor in disease susceptibility, i.e. the intensity of parasite infection in the subsequent generation

“Brains on a chip”: Towards engineered neural networks

The fundamental mechanisms of complex neural computation remain largely unknown, especially in respect to the characteristics of distinct neural circuits within the mammalian brain. The bottom-up approach of building well-defined neural networks with controlled topology has immense promise for improved reproducibility and increased target selectivity and response of drug action, along with hopes to unravel the relationships between functional connectivity and its imprinted physiological and pathological functions. In this review, we summarize the different approaches available for engineering neural networks treated analogously to a mathematical graph consisting of cell bodies and axons as nodes and edges, respectively. After discussing the advances and limitations of the current techniques in terms of cell placement to the nodes and guiding the growth of axons to connect them, the basic properties of patterned networks are analyzed in respect to cell survival and activity dynamics, and compared to that of in vivo and random in vitro cultures. Besides the fundamental scientific interest and relevance to drug and toxicology tests, we also visualize the possible applications of such engineered networks. The review concludes by comparing the possibilities and limitations of the different methods for realizing in vitro engineered neural networks in 2D