Identification of signal peptide peptidase,a presenilin-type aspartic protease

Signal peptide peptidase (SPP) catalyzes intramembrane proteolysis of some signal peptides after they have been cleaved from a preprotein. In humans, SPP activity is required to generate signal sequence-derived human lymphocyte antigen-E epitopes that are recognized by the immune system, and to process hepatitis C virus core protein. We have identified human SPP as a polytopic membrane protein with sequence motifs characteristic of the presenilin-type aspartic proteases. SPP and potential eukaryotic homologs may represent another family of aspartic proteases that promote intramembrane proteolysis to release biologically important peptides.     

Water level influences migratory patterns of anadromous brown trout in small streams

Habitats modify the population ecology of species. Here, we show how low water level influences abundance and size of adult anadromous brown trout (Salmo trutta) entering a small, South Norwegian stream for spawning. After smolting, the fish appear chiefly to feed within 10 km of the home stream. In the autumn, South Norwegian streams typically flood because of heavy rainfall, when the anadromous brown trout entered from the sea. Mean annual duration of the upstream migration period was 34 days and ended when the flooding ended and the water temperature dropped to below 4°C. During most of the migration period, on average two trout ascended the river per day. The sexes entered the spawning area concurrently, and the male:female ratio of the anadromous trout was 1.27. No fish entered when the water depth just downstream of the spawning area was below 5 cm, and mean number of fish increased with increasing water depth to ca. 30 cm, but not at higher flows when the ascent gradually decreased. Mean and maximum size of the entering spawners increased with water depth between 5 and 16 cm. Among those that had been to sea, most were recaptured in the home stream, 4% in other streams, but only two of the strays were caught close to spawning time. The present results illustrate that population traits of anadromous brown trout from a small stream differ from those in larger rivers, probably because of selection associated with water flow.     

Polypyrrole/polyacrylonitrile composite films: Dielectric, spectrophotometric and morphologic characterization

Spectrophotometric, morphologic and dielectric properties of polyacrylonitrile (PAN) composite films in the presence of pyrrole derivatives were reported in this paper. The composite films were fabricated by oxidative polymerization of pyrrole (Py), N-methyl pyrrole (NMPy) and N-phenyl pyrrole (NPhPy) by cerium(IV) on polyacrylonitrile matrix. The effect of temperature on the dielectric properties was studied in the frequency range from 0.05 Hz up to 10 MHz and in the temperature range from 0 °C up to 250 °C. Conductivity was increased with temperature due to increase of the mobility of charge carriers in the composite films. By increasing the temperature, the dipoles become free and respond to the applied electric field in composite structure; thus, the polarization and dielectric constant increases. PNPhPy-PAN composite films exhibited the highest dielectric constant, AC conductivity and tan delta.     

Successful mechanical eradication of spotted bass (Micropterus punctulatus (Rafinesque, 1819)) from a South African river

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Removal of Copper Ions from Simulated Wastewaters Using Different Bicomponent Polymer Membranes

Polybrominated diphenyl ethers (PBDEs) are a class of global flame retardants whose residues have markedly increased in fish and human tissues during the last decade. They belong to persistent and toxic contaminants which need more attention and toxicological study as their degradation in the environment is not well understood. This study characterizes 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) bioconcentration, elimination and biotransformation in juvenile turbot Psetta maxima, in order to evaluate the risk of its bioaccumulation in the marine environment. During this study, juvenile turbot were exposed to environmentally relevant BDE-47 concentrations from 0.001 to 1 μg/L for 16 days via aqueous exposure. This study found that juvenile turbot bioconcentrated and biotransformed BDE-47. There was no difference in standard length or weight between control and exposed fish. Uptake and elimination of BDE-47 by the turbot during exposure were examined in controlled laboratory experiments. Bioconcentration of BDE-47 was similar in fish from all treatment groups. Bioconcentration was rapid and increased with exposure time, since the bioconcentration factor (BCF) was higher. However, elimination was slower in comparison and low elimination was detected after 10 days in clean water. BDE-47 concentration in water influences the BCF. Half-life ranged between 37 and 108 days and theoretical times t ₉₀ could range from 120 to 358 days. The present study demonstrates a stepwise debromination of BDE-47 to BDE-28.

     

Understanding the adoption of smartphone apps in crop protection

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The adoption of drones in German agriculture: a structural equation model

Drones are one of the latest tools to have been added to farmers’ precision agriculture technology tool kit. Despite the proclaimed benefits, adoption rates of drones are low and literature regarding the adoption of drones in agriculture is scarce. Therefore, this study investigates whether an extended Technology Acceptance Model (TAM) can contribute to the understanding of latent factors influencing farmers’ intention to adopt a drone. The sample of 167 German farmers was collected in 2019 via an online survey. Using partial least squares structural equation modelling and a binary model, the TAM explains 69% of the variance in the intention to use a drone by German farmers. According to the results, raising farmers’ awareness of farm-specific areas of drone application and the confidence level of using a drone can increase farmers’ intention to adopt a drone. The results are of interest for agribusinesses developing drones as well as selling or providing drones. Furthermore, the results are of interest for researchers in precision agriculture technologies.

     

Resource use of crucian carp along a lake productivity gradient is related to body size,predation risk,and resource competition

Generalist fish species can feed on a wide resource spectrum and across trophic levels depending on resource availability and trophic interactions. Crucian carp (Carassius carassius) represents a good candidate species to investigate variation in the trophic ecology of generalist fish as it can be found in highly variable fish communities and its resource use is well documented. In this study, we explored the trophic ecology of crucian carp at the individual and population levels using stable isotope and gut content analysis. We tested if trophic resource use varied according to lake productivity, predation risk, intra- and interspecific competition, or individual fish size. We found that crucian carp resource preference was highly variable among and within lakes. In predator-free lakes, small crucian carp occurred in high densities, showed increased interindividual specialisation, and relied mainly on pelagic zooplankton. In presence of predators, large crucian carp occurred in low densities and included greater proportions of benthic macroinvertebrates in their diet. This shift in resource use was further favoured in productive, shallow lakes where littoral prey were probably abundant. Resource partitioning was an important factor determining crucian carp niche use, as fish had higher trophic position in absence of other cyprinids. Crucian carp showed highly dynamic resource use and food preferences in response to variable environmental conditions. Overlooking complex diet preferences of generalist fish may lead to an oversimplification of freshwater community dynamics.     

Course of infection and immune responses in the respiratory tract of IBV infected broilers after superinfection with E. coli

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