The depolarization-induced outflow of d-[H]aspartate from rat brain slices is modulated by metabotropic glutamate receptors

Rat brain slices were used to study the effects of different metabotropic glutamate receptor ligands on (i) the depolarization (30 mM KCl)-induced outflow of previously taken up d-[³H]aspartate; (ii) the inhibition of forskolin (30 μM)-induced cyclic AMP accumulation; and (iii) the hydrolysis of phosphoinositides. In addition, the localization of mRNAs coding for different metabotropic glutamate receptor subtypes was detected using in situ hybridization. (1S,3R)-1-Aminocyclopentane-1,3-dicarboxylic acid (30–300 μM), a non selective metabotropic glutamate receptor agonist, significantly increased the KCl-induced output of radioactivity from cortical slices, whereas it inhibited the output from striatal slices. Conversely, (1S,3S,4S)-carboxycyclopropylglycine (0.1–1 μM), a relatively selective agonist of the mGluR2 metabotropic glutamate receptor subtype, had an inhibitory effect on the output of d-[³H]aspartate from both cortical and striatal slices and proved to be the most potent metabotropic glutamate receptor agonist in inhibiting cyclic AMP accumulation, but not in stimulating phosphoinositide hydrolysis. Since 2-amino-4-phosphonobutyrate (a mGluR4, mGluR6 and mGluR7 agonist) was not active in any of the assays tested, we hypothesized that the mGluR2 subtype could be involved in these events. Accordingly, mGluR2 mRNA expression was abundant in cortical neurons projecting to the striatum. Our experiments suggest that the stimulation of metabotropic glutamate receptors may either decrease or increase transmitter release depending on the subtype that prevails in the region under study.     

Organic matter distribution and fluxes within a holm oak (Quercus ilex L.) stand in the Etna volcano

Located at 1100 m above sea level, on the western site of the Etna volcano, the ecophysiology of the Mount Minardo holm oak coppice has been investigated for more then twenty years. In this stand, now 31 years old, the above ground biomass amounts to 15000 g m^-2 of organic material, including leaves and perennial woody material. During these 31 years, the mean annual production has been around 775 g m^-2. The yearly mean litterfall amounts to 310 g m^-2, including 200 g m^-2 of leaves, mostly two years old. The soil surface is covered by a litter layer amounting to 3150 g m^-2. Each year, following Jenny's decomposition rate and field measurements, 290 g m^-2 of the litter turns into CO₂, or becomes incorporated in the soil organic matter.     

Novel albendazole formulations given during the intestinal phase of Trichinella spiralis infection reduce effectively parasitic muscle burden in mice

Trichinellosis is a zoonotic disease affecting people all over the world, for which there is no speedy and reliable treatment. Albendazole (ABZ), an inexpensive benzimidazole used in oral chemotherapy against helminthic diseases, has a broad spectrum activity and is well tolerated. However, the low absorption and variable bioavailability of the drug due to its low aqueous solubility are serious disadvantages for a successful therapy. In this study, we evaluated the in vivo antiparasitic activity of three novel solid microencapsulated formulations, designed to improve ABZ dissolution rate, in a murine model of trichinellosis. Both ABZ and the microparticulate formulations were administered during the intestinal phase of the parasite cycle, on days 5 and 6 post-infection. This protocol significantly decreased muscle larval burden measured in the parenteral phase, on day 30 post-infection, when compared with the untreated control. Moreover, two of the three microencapsulated formulations both strongly and consistently reduced worm burden.     

Using a gel/plastic surrogate to study the biomechanical response of the head under air shock loading: a combined experimental and numerical investigation

A combined experimental and numerical study was conducted to determine a method to elucidate the biomechanical response of a head surrogate physical model under air shock loading. In the physical experiments, a gel-filled egg-shaped skull/brain surrogate was exposed to blast overpressure in a shock tube environment, and static pressures within the shock tube and the surrogate were recorded throughout the event. A numerical model of the shock tube was developed using the Eulerian approach and validated against experimental data. An arbitrary Lagrangian-Eulerian (ALE) fluid–structure coupling algorithm was then utilized to simulate the interaction of the shock wave and the head surrogate. After model validation, a comprehensive series of parametric studies was carried out on the egg-shaped surrogate FE model to assess the effect of several key factors, such as the elastic modulus of the shell, bulk modulus of the core, head orientation, and internal sensor location, on pressure and strain responses. Results indicate that increasing the elastic modulus of the shell within the range simulated in this study led to considerable rise of the overpressures. Varying the bulk modulus of the core from 0.5 to 2.0 GPa, the overpressure had an increase of 7.2%. The curvature of the surface facing the shock wave significantly affected both the peak positive and negative pressures. Simulations of the head surrogate with the blunt end facing the advancing shock front had a higher pressure compared to the simulations with the pointed end facing the shock front. The influence of an opening (possibly mimicking anatomical apertures) on the peak pressures was evaluated using a surrogate head with a hole on the shell of the blunt end. It was revealed that the presence of the opening had little influence on the positive pressures but could affect the negative pressure evidently.     

Relation between the distribution and orientation of collagen fibers and the inorganic phase of calcification processes in the anterior leaflet of the human mitral valve

The collagen fibers observed in calcified valves appear randomly distributed without any preferential arrangement. In these areas also the hydroxylapatite crystals do not show any orientation. It is suggested that the disorder of the organic phase is a factor favouring the deposition of the calcium crystals.     

Human gut mycobiota tune immunity via CARD9-dependent induction of anti-fungal IgG antibodies

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Seasonal Dynamics of Prokaryotic Abundance and Activities in Relation to Environmental Parameters in a Transitional Aquatic Ecosystem (Cape Peloro,Italy)

This study examines the effects of temporal changes on microbial parameters in a brackish aquatic ecosystem. To this aim, the abundances of prokaryotes and vibrios together with the rates of enzymatic hydrolysis of proteins by leucine aminopeptidase (LAP), polysaccharides by β-glucosidase (GLU) and organic phosphates by alkaline phosphatase (AP), heterotrophic prokaryotic production (HPP), respiration (R), were seasonally investigated, during a 2-year period in the coastal area of Cape Peloro (Messina, Italy), constituted by two brackish lakes (Faro and Ganzirri). In addition, physical and chemical parameters (temperature, salinity, nutrients) and particulate organic carbon and nitrogen (POC, PN) were measured. The influence of multiple factors on prokaryotic abundances and activities was analysed. The results showed that Cape Peloro area is characterised by high seasonal variability of the microbial parameters that is higher than the spatial one. Combined changes in particulate matter and temperature (T), could explain the variability in vibrios abundance, GLU and R activities in both lakes, indicating a direct stimulation of the warm season on the heterotrophic prokaryotic metabolism. Positive correlations between T (from 13.3 to 29.6 °C) and HPP, LAP, AP, POC, PN are also observed in Ganzirri Lake. Moreover, the trophic status index and most of the microbial parameters show significant seasonal differences. This study demonstrates that vibrios abundance and microbial activities are responsive to the spatial and seasonal changes of examined area. The combined effects of temperature and trophic conditions on the microbial parameters lead us to suggest their use as potential indicators of the prokaryotic response to climate changes in temperate brackish areas.     

Larval anatomy and structure of absorbing epithelia in the aphid parasitoid Aphidius ervi Haliday (Hymenoptera, Braconidae)

The present work describes Aphidius ervi Haliday (Hymenoptera, Braconidae) larval anatomy and development, focusing on time-related changes of body structure and cell ultrastructure, especially of the epithelial layers involved in nutrient absorption. Newly hatched 1st instar larvae of A. ervi are characterised by gut absence and a compact cluster of cells makes up their body. As the parasitoid larva develops, the central undifferentiated cell mass becomes hollowed out, leading to the formation of gut anlage. This suggests that absorption of nutrients at that stage may take place through the body surface, as more directly demonstrated by the occurrence on the epidermis of proteins associated with transepithelial transport, such as Na(+)/K(+)-ATPase and alkaline phosphatase (ALP). Second instar larvae show the presence of the gut with a well-differentiated brush border and a peritrophic membrane. Gut cells are filled by masses of glycogen granules and lipid droplets. The tracheal system starts to be visible. The haemocoel becomes evident in late 2nd instar, and contains large silk glands. Mature 3rd instar larvae are typically hymenopteriform. The midgut accounts for most of the body volume and is actively involved in nutrient absorption, as indicated by the well developed brush border and by the presence of Na(+)/K(+)-ATPase and ALP on the basolateral and luminal membrane respectively. At this stage, large lipid droplets have gradually replaced the cellular glycogen stores in the midgut cells. The tracheae are completely differentiated, but their internal lumen still contains fibrillar material, suggesting that they are not functional as long as host fluids bath the parasitoid larva. In late 3rd instar larvae, silk glands, structurally similar to Malpighian tubules, show a very intense vesicular traffic toward the internal lumen, which, eventually, results in being filled by secretion products, suggesting the possible recycling of metabolic waste products during mummy formation.     

Morphology, cytology and taxonomic remarks of four species of Stigeoclonium (Chaetophorales, Chlorophyceae) from Argentina

Four species of Stigeoclonium from Argentina were studied by means of transmission electron microscopy and light microscopy. For species identification, we collected data related to the prostrate system and zoospore germination. We also determined the chromosome number for each species. Stigeoclonium aestivale showed a more developed erect system than the prostrate one, zoospore germination was predominantly of erect type and the chromosome number was 8. Stigeoclonium tenue presented well developed, erect and prostrate systems, zoospore germination was initially of the prostrate type and the chromosome number was 5. In Stigeoclonium variabile the prostrate system predominated over the erect one, zoospore germination was strictly of the prostrate type and the chromosome number was 3. Stigeoclonium farctum presented a more developed prostrate system than the erect one, zoospore germination was strictly of the prostrate type and the chromosome number was 8. The ontogeny of the zoospore germination was related to the final relative development of the prostrate and erect portions of adult thalli.