Time-dependent changes in ghrelin-immunoreactivity in dissociated neuronal cultures of the newborn rat neocortex

Ghrelin is a hormone, initially described as a gastric peptide stimulating appetite and growth hormone secretion, which also has an important role in the regulation of many other processes, including higher brain functions. Ghrelin has been described in situ in different parts of the brain, but so far there has been no data about its expression in cell cultures. Therefore, we aimed in this study to investigate the levels of ghrelin in dissociated cortical neurons at various times in culture. We applied the ABC immunocytochemical method for the detection of ghrelin in one-day-, one-week-, and two-week-old cultures. Our results clearly show that at the early stages after plating the cultures 86.2% (± 8.93) of the neurons are ghrelin-positive and their number decreases during the culturing period. As ghrelin is present in the majority of cultured newborn neurons, when the neuronal differentiation and network formation take place, it may also influence the early synaptic formation and cell-to-cell interactions, which are both very important for network functions like learning and memory.     

Présence d'un Gomphotheriidae indet. (Proboscidea, Mammalia) dans la faune vallésienne d'Afoud AF6 (Bassin d'Aït Kandoula, Maroc), établie d'après la microstructure de l'émail d'un fragment de molaire

The Aït Kandoula basin is one of the richest Miocene micromammals bearing areas known in the South of the High-Atlas, whereas the large mammal remains are scarce. The Afoud section in the center of the basin is well calibrated with the Geomagnetic Polarities Time Scale (KC95), and shows a succession of six fossiliferous layers. Beside rodents, the Afoud AF6 layer yields among some large mammal remains, a proboscidean identified as a Gomphotheriidae indet. from the enamel microstructure of a molar chip. This determination is grounded on the thickness of the enamel, on the prisms type, on the thinness and characteristics of the 3D zone and outside on the preferential course of the prisms.     

Topographic information improves simulated patterns of post-fire conifer regeneration in the southwest United States

The western United States is projected to experience more frequent and severe wildfires in the future due to drier and hotter climate conditions, exacerbating destructive wildfire impacts on forest ecosystems such as tree mortality and unsuccessful post-fire regeneration. While empirical studies have revealed strong relationships between topographical information and plant regeneration, ecological processes in ecosystem models have either not fully addressed topography-mediated effects on the probability of plant regeneration, or the probability is only controlled by climate-related factors, for example, water and light stresses. In this study, we incorporated seedling survival data based on a planting experiment in the footprint of the 2011 Las Conchas Fire into the Photosynthesis and EvapoTranspiration (PnET) extension of the LANDIS-II model by adding topographic and an additional climatic variable to the probability of regeneration. The modified algorithm included topographic parameters such as heat load index and ground slope and spring precipitation. We ran simulations on the Las Conchas Fire landscape for 2012–2099 using observed and projected climate data (i.e., Representative Concentration Pathway 4.5 and 8.5). Our modification significantly reduced the number of regeneration events of three common southwestern conifer tree species (piñon, ponderosa pine, and Douglas-fir), leading to decreases in aboveground biomass, regardless of climate scenario. The modified algorithm decreased regeneration at higher elevations and increased regeneration at lower elevations relative to the original algorithm. Regenerations of three species also decreased in eastern aspects. Our findings suggest that ecosystem models may overestimate post-fire regeneration events in the southwest United States. To better represent regeneration processes following wildfire, ecosystem models need refinement to better account for the range of factors that influence tree seedling establishment. This will improve model utility for projecting the combined effects of climate and wildfire on tree species distributions.     

The laser in the Lowry technique for microdissection of freeze-dried tissue slices

Synopsis A new technique for tissue microdissection is described. This procedure, using an u.v.-laser micropreparation instrument, overcomes the extremely timeconsuming manual preparation. The u.v.-laser micropreparation design allows fast, precise, reproducible and smear-contamination-free tissue microdissection. The preparation of the tissue sample can be programmed by tracing out the area to be sampled with a non-destructive 0.5 m W He-Ne-laser aiming-beam. The trace is stored in a small electronic unit, which then guides the motor-driven stepping stage on the microscope in the actual dissection run with the u.v.-laser.The laser power is adjustable in the range 4 to 40 kW and controlled by a photo diode displayed on an oscilloscope screen. In the tissue slice, prepared according to Lowry, an unlimited number of cells or tissue compartments can be dissected and afterwards weighed. The procedure described offers a broader use of the quantitative microhistochemical techniques of Lowry and of Neuhoff.Paper given at the Royal Microscopical Society's European Histochemistry Meeting at Nottingham in September, 1975.     

31P Nuclear Magnetic Resonance In Vivo Spectroscopy of the Metabolic Changes Induced in the Awake Rat Brain During KCN Intoxication and Its Reversal by Hydroxocobalamine

Radiofrequency surface coils were chronically implanted in rats, which were subsequently subjected to 31P nuclear magnetic resonance (NMR) investigations at 4.7 T. The implanted coil allowed study of the animals without need for anesthesia, which is a prerequisite for studies of normal brain metabolism. The animals may be kept in the NMR probe for several hours. During subsequent experiments, they may be placed in the same position, therefore allowing follow-up studies for periods as long as 2 months. This method has been used in the study of sublethal KCN intoxication. KCN, a cytochrome c oxidase inhibitor, induces a blockade of cell respiratory processes, which is reflected, in a dose-dependent manner, by a decrease in phosphocreatine content and pH and an increase in inorganic phosphate content, whereas ATP levels remain constant until high doses of KCN (6 mg/kg i.p.) are reached. 31P NMR allows the time course of these metabolic changes to be followed. For high KCN doses, a new peak, termed X, is observed, which is interpreted as being due to a pool of inorganic phosphate at very low pH (5.65), corresponding to a subset of cells that did not survive KCN injury. Hydroxocobalamine, a specific antidote of KCN, suppresses the metabolic changes due to 6 mg/kg of KCN.     

Accumulation of dinucleoside polyphosphates in Saccharomyces cerevisiae under stress conditions. High levels are associated with cell death

Adenosine tetraphosphonucleosides (Ap4X) were measured in Saccharomyces cerevisiae by a coupled phosphodiesterase-luciferase assay. After exposure of the cells to cadmium or to hyperthermic treatment (46 degrees C) a marked increase of the cellular pool from 0.08 microM (base level) to 4 microM or higher was observed. The accumulation of Ap4X to high levels is associated with irreversible processes leading to cell death.