Seasonal physiological responses of Argania spinosa tree from Mediterranean to semi-arid climate

Argania spinosa (the argan tree) is a slow-growing tree endemic of Morocco, growing on semi-arid areas where no other tree species can live. With the aim of predicting temporal changes in A. spinosa woodlands under a probable increase in aridity, we set off to investigate these questions: how do A. spinosa physiological attributes respond to variations in climatic conditions and seasonality, and which is the set of attributes that most affects tree response to environmental conditions? In three study sites, Beni Snassen (North), High-Atlas (Mountain) and Admine Forest in Agadir (Coastal), gas exchange measurements, photochemical efficiency, leaf water potential and different leaf attributes were monitored in February, July and November of 2006. The Mountain site presents the most continental climate. Trees in this site were the most stressed in summer, having the lowest midday leaf water potential values, photochemical efficiency and assimilation rates. We found a Ψ_md threshold around -4 MPa, below which stomatal conductance responds linearly to Ψ_md. Plants from the North area never reached this threshold during the study period. Although leaf pigments presented a clear seasonal pattern, leaves from Coastal trees exhibit the highest content for each season. The three study sites were separated by two discriminate functions obtained by canonical discriminant analysis. In summer, the Mountain population is separated from the other sites mainly by assimilation rate and F_v/F_m, while in winter transpiration rates and chlorophyll content are the main discriminant variables. Our study shows that A. spinosa trees adjust their physiological status and leaf attributes to environmental conditions allowing plants to thrive under a dry climate. Under a scenario of global change, the distribution of the argan tree likely shifts to milder areas.     

Trophic niche changes associated with habitat fragmentation in a Neotropical bat species

Habitat fragmentation could alter ecological traits including species trophic habits. Here, we used carbon and nitrogen stable isotope ratios to establish differences in isotopic niche width and food resource use between forest fragments and the continuous forest for the phyllostomid frugivorous bat Artibeus lituratus. Using mist nests, we captured bats from two forest fragments and two sites in continuous forest, and sampled from each individual captured three body tissues with contrasting turnover rates (skin, muscle, and liver). Samples were collected between February and March (austral summer) and between August and September (austral winter). In addition, in each sampling site and season we collected potential food resources (fruits and insects) consumed by our A. lituratus. Our findings indicate that A. lituratus had a predominantly omnivorous diet, with high consumption of insects during summer in forest fragments. The increasing consumption of insects in these fragments seems to have led to a wider isotopic niche, in relation to the continuous forest. Because A. lituratus is typically a seed disperser, changes in trophic habits in the forest fragments from frugivory to insectivory may diminish their role in forest regeneration. Abstract in Portuguese is available with online material.     

Passage of serum-destined proteins through the Golgi apparatus of rat liver. An examination of heavy and light Golgi fractions

The participation of hepatic Golgi apparatus in the intracellular transport of blood-destined proteins has been analyzed using Golgi fractions enriched in cis and trans components of the Golgi apparatus. SDS-polyacrylamide gel electrophoresis of the liver Golgi fractions showed several proteins corresponding in relative proportions and mobilities with serum proteins. After a pulse injection of labeled leucine, the secretory content of the cis Golgi fraction was labeled earlier than the trans Golgi fraction. Taken together, the results show the participation of the liver Golgi apparatus in the secretion of most of the serum proteins and provide documentation for a sequential progression of secretory protein through the cis and trans components of the Golgi apparatus.     

Isoenzyme characterization of proteases and amylases and partial purification of proteases from filamentous fungi causing biodeterioration of industrial paper

Biodeterioration is an undesirable process that can affect cultural heritage and economically important materials. Although several biotic and abiotic conditions can accelerate this process, microorganisms are perhaps its main promoters. Fungi are the most important microbial agents of biodeterioration of industrial paper stored in archives. The high genetic plasticity of these organisms allows them to adapt to different environments, using almost any class of materials as substrate. Fungi produce a wide array of enzymes, including cellulases, amylases, and proteases, which are responsible for their gross biodeterioration activity. Thirty-two morphotypes of filamentous fungi were isolated on different media from industrial paper at an advanced stage of biodeterioration. The isolates showed different degrees of cellulolytic, proteolytic, and amylolytic activities on plate assays. The highest proteolytic and amylolytic activities were selected for isoform characterization, which provided an indication of the biochemical diversity that allowed them to colonize these materials. Eladia sacculum was the morphotype selected for partial purification of basic proteases since it has three basic isoforms, simplifying the purification process. We obtained a protein of 35 kDa with a pI of 8.9.     

Disulfide bond polymerization of a cyclic peptide derived from the surface loop 4 of class 1 OMP of Neisseria meningitidis

Two peptides derived from the surface loop 4 of class1 Outer Membrane Protein (OMP) of Neisseriameningitidis were synthesized on solid phase usingthe Boc/Bzl strategy: one containing the entire loop4 cyclized and the other representing the polymerizedcyclic loop 4. To test a more efficient cyclic peptidepresentation, in the present study astrategy was developed to obtain polymers of cyclic peptides. Inorder to obtain the polymeric cyclic peptide, twoprotecting groups for cysteine were used – Acm andMob. The Cys(Acm)-protected cyclic peptide wasobtained after removing the Mob group. Thepolymerization reaction was carried out bysimultaneous deprotection/oxidation of S-Acmwith iodine. Analysis of the polymeric cyclic peptidein Tris-tricine-SDS-PAGE showed different bandswith molecular weights higher than expected for thecorresponding monomeric cyclic peptide. Both peptideswere used in immunization of four different mouse strains.The antisera raised against the peptides wereevaluated by ELISA and Western blotting vs. OMPpreparation of N. meningitidis. The titersraised against the polymerized cyclic peptide werehigher than the ones raised against the cyclicpeptide. The antisera elicited did not showbactericidal activity. Nevertheless, the antiseraelicited against the polymeric cyclic peptide in theCBA/J mouse strain showed opsonic activity. Theantibodies raised against the polymeric cyclic peptidewere successfully used as probes in Western blottingexperiments to verify the display of loop 4 peptide onthe surface of filamentous phage M13.     

Veratridine-stimulated central synapses in culture: A quantitative ultrastructural analysis

Synapses in explant cultures of fetal rat neocortex at day 18 in vitro were stimulated by veratridine (10^?4M) for 20 min. The cultures were subsequently processed for electron microscopy and the synapses were analyzed by quantitative techniques, incorporating set mathematical treatment. The mean values of area, perimeter, and form factor of the presynaptic elements significantly increased following veratridine stimulation, compared to the values of control synapses. The length of the postsynaptic thickening also increased, while synaptic curvature did not change significantly in the veratridine group. A fivefold reduction was observed in the mean number of synaptic vesicles per presynaptic element and in the vesicle-terminal area ratio, following veratridine stimulation. The cytoplasm-terminal area ratio and the occurrence of vacuoles/cisternae significantly increased after veratridine application. Planar measurement of membranes (boundary length) of different presynaptic organelles revealed that the total membrane did not change significantly in the veratridine group. The data indicated an increase in volume and swelling of the pre- and postsynaptic elements, considerable depletion of synaptic vesicles, and preservation of the total presynaptic membrane following veratridine stimulation in nerve tissue culture.     

Dasatinib Reduces Lung Inflammation and Fibrosis in Acute Experimental Silicosis

Silicosis is an occupational lung disease with no effective treatment. We hypothesized that dasatinib, a tyrosine kinase inhibitor, might exhibit therapeutic efficacy in silica-induced pulmonary fibrosis. Silicosis was induced in C57BL/6 mice by a single intratracheal administration of silica particles, whereas the control group received saline. After 14 days, when the disease was already established, animals were randomly assigned to receive DMSO or dasatinib (1 mg/kg) by oral gavage, twice daily, for 14 days. On day 28, lung morphofunction, inflammation, and remodeling were investigated. RAW 264.7 cells (a macrophage cell line) were incubated with silica particles, followed by treatment or not with dasatinib, and evaluated for macrophage polarization. On day 28, dasatinib improved lung mechanics, increased M2 macrophage counts in lung parenchyma and granuloma, and was associated with reduction of fraction area of granuloma, fraction area of collapsed alveoli, protein levels of tumor necrosis factor-α, interleukin-1β, transforming growth factor-β, and reduced neutrophils, M1 macrophages, and collagen fiber content in lung tissue and granuloma in silicotic animals. Additionally, dasatinib reduced expression of iNOS and increased expression of arginase and metalloproteinase-9 in silicotic macrophages. Dasatinib was effective at inducing macrophage polarization toward the M2 phenotype and reducing lung inflammation and fibrosis, thus improving lung mechanics in a murine model of acute silicosis.