Large herbivores as mobile links between isolated nature reserves through adhesive seed dispersal

Question: Do large herbivores contribute to the dispersal of plant seeds between isolated habitats by epizoochory? Location: Nature reserves in Flanders, Belgium. Methods: Epizoochory was studied by brushing plant seeds from the fur of 201 domesticated large herbivores (Galloway cattle, donkeys and horses), grazing in 27 Flemish nature reserves. Several herbivores were examined after transport between different nature reserves as part of the seasonal grazing system in Flanders, allowing detection of seed dispersal both within and between reserves. The seedling emergence method was used to identify the dispersed plant species. Results: In total, 6385 epizoochorous seeds from 75 species germinated, yet the real seed quantity was underestimated by the seedling emergence method. A wide variety of seed morphology, seed weights and plant heights was represented among the dispersed species, many of which had a transient seed bank. There was a gradual turnover in epizoochorous species composition in the course of the vegetation season, and seed dispersal occurred both within and between different nature reserves. Conclusions: Domesticated large herbivores, as models for wild mammals in the present and the past, are important dispersers of many plant species. Through seasonal grazing, the herbivores function as ‘mobile link organisms’, connecting isolated nature reserves through seed dispersal, possibly influencing vegetation development and long‐term survival of plant populations. As such, large herbivores are important instruments in ecological restoration, especially in fragmented ecosystems.     

A Comparison of the Efficacy of Pond-Net and Box Sampling Methods in Turloughs - Irish Ephemeral Aquatic Systems

Two methods were used to sample aquatic macroinvertebrates in three turloughs. Turloughs are systems that flood periodically from groundwater, in response to local rainfall patterns and contain rare aquatic species and assemblages. The first method used a standard pond net that was swept through the water column, while the second involved fixing a rectangular, open-bottomed box to the substrata and removing all organisms with a net. Similar overall sampling effort was applied to each method and individual box samples were found to take longer to gather than pond net samples. The box method, however, gave the maximum yield for a given sampling effort. Significantly more beetle species and individuals were recorded per unit area of bottom at all three turloughs using the box method. Multivariate analysis segregated samples, firstly according to site and secondly, with respect to method. The box method is a viable alternative to sampling with a pond net. It is more quantitative, objective, specific and reliable. This is particularly important in habitats distinguished by rare species and assemblages, and for which monitoring is driven by legislative needs.     

Leukotriene A4 hydrolase/aminopeptidase. Glutamate 271 is a catalytic residue with specific roles in two distinct enzyme mechanisms.

Leukotriene A(4) hydrolase/aminopeptidase is a bifunctional zinc metalloenzyme that converts the fatty acid epoxide leukotriene A(4) into leukotriene B(4), a potent chemoattractant and immune-modulating lipid mediator. Recently, the structure of leukotriene A(4) hydrolase revealed that Glu-271, which belongs to a conserved GXMEN motif in the M1 family of zinc peptidases, and Gln-136 are located at the active site. Here we report that mutagenetic replacements of Glu-271, but not Gln-136, abrogate both catalytic activities of leukotriene A(4) hydrolase. Furthermore, the 2.1 A crystal structure of [E271Q]leukotriene A(4) hydrolase revealed minimal conformational changes that could not explain the loss of enzyme function. We propose that the carboxylate of Glu-271 participates in an acid-induced opening of the epoxide moiety of leukotriene A(4) and formation of a carbocation intermediate. Moreover, Glu-271 appears to act as an N-terminal recognition site and may potentially stabilize the transition-state during turnover of peptides, a property that most likely pertains to all members of the M1 family of zinc aminopeptidases. Hence, Glu-271 is a unique example of an amino acid, which has dual and separate functions in two different catalytic reactions, involving lipid and peptide substrates, respectively.     

Slow Delivery of the Selective Cholecystokinin Agonist pBC 264 into the Rat Nucleus Accumbens Using Microspheres

Abstract: Neuropeptides have been shown to play a critical role in adaptational processes, probably by long-term modulation of neuronal pathways. It could therefore be interesting to study behavioral changes induced by chronic local stimulation of neuropeptide receptors. With this aim poly(lactide-co-glycolide) microspheres loaded with a highly potent, peptidase-resistant, cholecystokinin (CCK)-B-selective CCK peptidomimetic agonist (pBC 264) were prepared by a water in oil in water emulsion solvent evaporation method and stereotaxically implanted into the anterior part of the rat nucleus accumbens. Two different kinds of loaded polymeric microspheres differing only by the stabilizing agent [ovalbumin (OVA) or Pluronic F 68] added to the inner emulsion were used. The histological and behavioral studies done 24 h and 8 days after implantation of nonloaded microspheres in the nucleus accumbens indicated that the microspheres were well tolerated. The in vivo release of the selective CCK-B agonist pBC 264 (associated with a tracer dose of [³H]pBC 264) from microspheres prepared with OVA was very fast (92% after 6 h), whereas only 26% (88 pmol) of pBC 264 was released from the formulation with Pluronic F 68 after 24 h. Eight days after implantation 36% of pBC 264 had diffused from the microspheres, and 8% (∼30 pmol) was still present in the brain concentrated around the site of administration. In all cases the released material was found to correspond to intact pBC 264, thus demonstrating the possibility of obtaining a slow controlled release of peptide in vivo. This method opens up interesting perspectives to study the long-term effects of neuropeptides.     

Low-dose Ad26.COV2.S protection against SARS-CoV-2 challenge in rhesus macaques

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Penicillium discolor, a new species from cheese, nuts and vegetables

The new species Penicillium discolor, frequently isolated from nuts, vegetables and cheese is described. It is characterised by rough, dark green conidia, synnemateous growth on malt agar and the production of the secondary metabolites chaetoglobosins A, B and C, palitantin, cyclopenin, cyclopenol, cyclopeptin, dehydrocyclopeptin, viridicatin and viridicatol. It also produces the mouldy smelling compounds geosmin and 2-methyl-isoborneol, and a series of specific orange to red pigments on yeast extract sucrose agar, hence the epithet discolor. P. discolor resembles P. echinulatum morphologically but on basis of the secondary metabolites is also related to P. expansum, P. solitum and P. crustosum.     

Simultaneous determination of eight lipid peroxidation degradation products in urine of rats treated with carbon tetrachloride using gas chromatography with electron-capture detection

One of the major processes that occur as a result of radical-induced oxidative stress is lipid peroxidation (LPO). Degradation of lipid peroxides results in various products, including a variety of carbonyl compounds. In the present study eight different lipid degradation products, i.e., formaldehyde, acetaldehyde, acetone, propanal, butanal, pentanal, hexanal and malondialdehyde were identified and measured simultaneously and quantitatively in rat urine after derivatization with O-(2,3,4,5,6-pentafluorbenzyl)hydroxylamine hydrochloride, extraction with heptane and using gas chromatography–electron-capture detection (GC–ECD). The identity of the respective oximes in urine was confirmed by gas chromatography–negative ion chemical ionization mass spectrometry (GC–NCI-MS). Simultaneously measured standard curves were linear for all oxime-products and the detection limits were between 39.0±5.3 (n=9) and 500±23 (n=9) fmol per μl injected sample. Recoveries of all products from urine or water were 73.0±5.2% and higher. In urine of CCl₄-treated rats an increase in all eight lipid degradation products in urine was found 24 h following exposure. ACON showed the most distinct increase, followed by PROPA, BUTA and MDA. It is concluded that the rapid, selective and sensitive analytical method based on GC–ECD presented here is well suited for routine measurement of eight different lipid degradation products. These products appear to be useful as non-invasive biomarkers for in vivo oxidative stress induced in rats by CCl₄.     

A new generation of polymer nanoparticles for drug delivery.

One of the main interests of using polymer nanoparticles as drug carrier systems is to control the delivery of the drugs including their biodistribution. During the last decade, it was clearly demonstrated that surface properties of nanoparticles were the key factor which determined the in vivo fate of such a carrier. Thus, the purpose of this work was to develop a new method which allows the easy fabrication of nanoparticles with versatile surface properties using polysaccharides. This preparation was based on the use of a redox radical polymerization reaction applied for the first time to the emulsion polymerization of alkylcyanoacrylates in aqueous continuous media. The dispersion of nanoparticles was very stable. The nanoparticle surfaces were coated with polysaccharides and their characteristics can be modulated by the type and the molecular weight of the polysaccharides used during the synthesis. Interestingly the biological properties of the polysaccharide immobilized on the nanoparticle surface can be preserved opening very interesting perspectives for such nanoparticles. This method also offers a new strategy for the design of modular biomimetic nanoparticles as drug carrier systems with multiple functions. One of the applications considered in this work was to use these nanoparticles coupled with haemoglobin as an oxygen carrier.