Cytochemical detection of polysaccharides on the surface of the cell membrane complex in fungi

Cytochemical staining in toto (periodic acid, thiosemicarbazide, O_SO₄) revealed the presence of polysaccharide lamellae on the surface of the cell membrane complex of fungi. The membraneous clusters in the vacuolar bodies of Claviceps purpurea were covered with these lamellae at both surfaces, as it was also the case with the endoplasmic reticulum membranes, the tonoplast and the cytoplasmic membrane. In Saccharomyces cerevisiae, the polysaccharide lamellae were visible on the surface of the endoplasmic reticulum membranes and the plasmalemma; the strain revealed polysaccharide deposits also on the tonoplasts of small vacuoles and in glucanase vesicles. We assume that these observations give precision to the localization of the enzymes synthetizing the glycoprotein components of the fungal cell wall.     

Immunity functions of Arabidopsis pathogenesis-related 1 are coupled but not confined to its C-terminus processing and trafficking

The pathogenesis-related 1 (PR1) proteins are members of the cross-kingdom conserved CAP superfamily (from Cysteine-rich secretory protein, Antigen 5, and PR1 proteins). PR1 mRNA expression is frequently used for biotic stress monitoring in plants; however, the molecular mechanisms of its cellular processing, localization, and function are still unknown. To analyse the localization and immunity features of Arabidopsis thaliana PR1, we employed transient expression in Nicotiana benthamiana of the tagged full-length PR1 construct, and also disrupted variants with C-terminal truncations or mutations. We found that en route from the endoplasmic reticulum, the PR1 protein transits via the multivesicular body and undergoes partial proteolytic processing, dependent on an intact C-terminal motif. Importantly, only nonmutated or processing-mimicking variants of PR1 are secreted to the apoplast. The C-terminal proteolytic cleavage releases a protein fragment that acts as a modulator of plant defence responses, including localized cell death control. However, other parts of PR1 also have immunity potential unrelated to cell death. The described modes of the PR1 contribution to immunity were found to be tissue-localized and host plant ontogenesis dependent.     

Seasonal habitat selection and temporal activity patterns determine the structure of bat assemblages in Dhana Biosphere Reserve,Jordan (Mammalia: Chiroptera)

We measured species richness, diversity, and diel activity patterns of insectivorous bats at four sites within Dhana Biosphere Reserve. A total of seven species belonging to five families at varying species compositions were recorded. Four to six species were present at these sites and total diversity ranged between 0.32 at Ain Lahtha and 0.65 at Al Khararah. Overall frequency of passes was highest at Shaq Kalbeh. The Common Pipistrelle, Pipistrellus pipistrellus, was the most prevalent at three sites, followed by the Arabian Horseshoe Bat, Rhinolophus clivosus, and Botta’s Serotine, Eptesicus bottae. Natterer’s Bat, Myotis nattereri, and the European Free-tailed Bat, Tadarida teniotis, occurred at low abundance. The Lesser Horseshoe Bat, Rhinolophus hipposideros, occurred at a higher abundance within Finan site (arid site at lower altitude), whereas the Egyptian Mouse-tailed Bat, Rhinopoma cystops, was restricted to Finan. The overall mean number of bat passes was not significantly different between sites. Average seasonal species diversity was low during winter (none at Ain Lahtha and Shaq Kalbeh) and highest during summer (0.68 at Al Kharrarah). Seasonal activity patterns for each site in terms of frequencies of bat passes on an hourly basis are given.     

The influence of serum‐supplemented culture media in a transwell migration assay

Our work cautions against the use of serum‐supplemented culture media in a transwell migration assay when using chemoattractants other than FBS. At 24 h, a 5% foetal bovine serum (FBS) gradient caused BV2 microglia to migrate toward the lower compartment of the transwell apparatus. Interestingly, FBS‐supplemented media in the absence of a gradient also resulted in notable microglia migration. Serum can therefore confound the interpretation of a transwell migration assay when another chemoattractant is used.     

Frataxin, a conserved mitochondrial protein, in the hydrogenosome of Trichomonas vaginalis

Recent data suggest that frataxin plays a key role in eukaryote cellular iron metabolism, particularly in mitochondrial heme and iron-sulfur (FeS) cluster biosynthesis. We have now identified a frataxin homologue (T. vaginalis frataxin) from the human parasite Trichomonas vaginalis. Instead of mitochondria, this unicellular eukaryote possesses hydrogenosomes, peculiar organelles that produce hydrogen but nevertheless share common ancestry with mitochondria. T. vaginalis frataxin contains conserved residues implicated in iron binding, and in silico, it is predicted to form a typical alpha-beta sandwich motif. The short N-terminal extension of T. vaginalis frataxin resembles presequences that target proteins to hydrogenosomes, a prediction confirmed by the results of overexpression of T. vaginalis frataxin in T. vaginalis. When expressed in the mitochondria of a frataxin-deficient Saccharomyces cerevisiae strain, T. vaginalis frataxin partially restored defects in heme and FeS cluster biosynthesis. Although components of heme synthesis or heme-containing proteins have not been found in T. vaginalis to date, T. vaginalis frataxin was also shown to interact with S. cerevisiae ferrochelatase by using a Biacore assay. The discovery of conserved iron-metabolizing pathways in mitochondria and hydrogenosomes provides additional evidence not only of their common evolutionary history, but also of the fundamental importance of this pathway for eukaryotes.     

Close relation of arterial ICC-like cells to the contractile phenotype of vascular smooth muscle cell

This work aimed to establish the lineage of cells similar to the interstitial cells of Cajal (ICC), the arterial ICC-like (AIL) cells, which have recently been described in resistance arteries, and to study their location in the artery wall. Segments of guinea-pig mesenteric arteries and single AIL cells freshly isolated from them were used. Confocal imaging of immunostained cells or segments and electron microscopy of artery segments were used to test for the presence and cellular localization of selected markers, and to localize AIL cells in intact artery segments. AIL cells were negative for PGP9.5, a neural marker, and for von Willebrand factor (vWF), an endothelial cell marker. They were positive for smooth muscle alpha-actin and smooth muscle myosin heavy chain (SM-MHC), but expressed only a small amount of smoothelin, a marker of contractile smooth muscle cells (SMC), and of myosin light chain kinase (MLCK), a critical enzyme in the regulation of smooth muscle contraction. Cell isolation in the presence of latrunculin B, an actin polymerization inhibitor, did not cause the disappearance of AIL cells from cell suspension. The fluorescence of basal lamina protein collagen IV was comparable between the AIL cells and the vascular SMCs and the fluorescence of laminin was higher in AIL cells compared to vascular SMCs. Moreover, cells with thin processes were found in the tunica media of small resistance arteries using transmission electron microscopy. The results suggest that AIL cells are immature or phenotypically modulated vascular SMCs constitutively present in resistance arteries.     

Sampling design in large-scale vegetation studies: Do not sacrifice ecological thinking to statistical purism!

Most of the historical phytosociological data on vegetation composition have been sampled preferentially and thus belong to those ecological data that do not fulfill the statistical assumption of independence of observations, necessary for valid statistical testing and inference. Nevertheless, phytosociological data have been recently used for various ecological meta-analyses, especially in studies of large-scale vegetation patterns. For this reason, we focus on the comparison of preferential sampling with other sampling designs that have been recommended as more convenient alternatives from the point of view of statistical theory. We discuss that while simple random sampling, systematic sampling and stratified random sampling better meet some of the statistical assumptions, preferential sampling yields data sets that cover a broader range of vegetation variability. Moreover, today’s large phytosociological databases provide huge amounts of vegetation data with unrivalled geographic extent and density. We conclude that in the near future ecologists will not be able to replace the preferentially sampled phytosociological data in large-scale studies. At the same time, phytosociological databases have to be complemented with relevés of vegetation composed mostly of common and generalist species, which are under-represented in historical data. Stratified random sampling seems to be a suitable tool for doing this. Nevertheless, a methodology and input data for stratification have to be developed to make stratified random sampling an ecologically more relevant and practical method.     

Applications of ionic liquids in carbohydrate chemistry: a window of opportunities

Ionic liquids (ILs) are composed only of ions. Of special interest to this review are those where at least one ion (the cation) is organic and whose melting points are below or not far above room temperature. ILs are designated as "green" solvents because they have extremely low vapor pressure, are non-inflammable, and thermally and chemically stable. Therefore, many of them can be, in principle, recycled into the process indefinitely. The objective of the present review is to discuss different aspects of the use of ILs in carbohydrate chemistry, in particular, dissolution and functionalization of simple sugars, cyclodextrins, cellulose, starch, and chitin/chitosan. The molecular structure and synthesis of ILs most frequently employed in carbohydrate chemistry are discussed with an emphasis on imidazolium and pyridinium cations with different counterions. The physicochemical properties of ILs that are relevant to the dissolution and functionalization of carbohydrates, in particular their polarities and hydrogen-bonding abilities, are discussed. Dissolution of simple saccharides and biopolymers in ILs is presented with an emphasis on the mechanism of carbohydrate--IL interactions. Finally, the very interesting novel applications of the solutions obtained are addressed. These include, inter alia, spinning of the dissolved biopolymer into fibers, extrusion into slabs and rods, formation of matrixes for a myriad of substrates, including biomacromolecules, formation of nanocomposites, and functionalization to produce important derivatives. The use of ILs in many branches of science is expanding fast; it is hoped that this review will draw the attention of researchers to the "window of opportunities" that these green solvents open into carbohydrate chemistry.