A fast model of voltage-dependent NMDA receptors

NMDA receptors are among the crucial elements of central nervous system models. Recent studies show that both conductance and kinetics of these receptors are changing voltage-dependently in some parts of the brain. Therefore, several models have been introduced to simulate their current. However, on the one hand, kinetic models—which are able to simulate these voltage-dependent phenomena—are computationally expensive for modeling of large neural networks. On the other hand, classic exponential models, which are computationally less expensive, are not able to simulate the voltage-dependency of these receptors, accurately. In this study, we have modified these classic models to endow them with the voltage-dependent conductance and time constants. Temperature sensitivity and desensitization of these receptors are also taken into account. We show that, it is possible to simulate the most important physiological aspects of NMDA receptor’s behavior using only three to four differential equations, which is significantly smaller than the previous kinetic models. Consequently, it seems that our model is both fast and physiologically plausible and therefore is a suitable candidate for the modeling of large neural networks.     

Nano silver: a novel nanomaterial for removal of bacterial contaminants in valerian (Valeriana officinalis L.) tissue culture

Bacterial contamination is a serious problem in plant tissue culture procedures. An experiment was conducted to evaluate the potential of nano silver (NS) to remove bacterial contaminants of valerian nodal explants. This experiment was conducted as a completely randomized design in a factorial arrangement with four replications and each replicate with ten explants. Treatments involved NS at two stages (before and after surface sterilization along with control) with three rates (25, 50 and 100 mg l⁻¹) at three times of soaking (30, 60 and 180 min). Explants were cultured on MS medium supplemented with 5 mg l⁻¹ Kin and 0.1 mg l⁻¹ NAA. Results showed that using 100 mg l⁻¹ of NS solution after surface sterilization resulted in the highest percentage (89%) of disinfected explants. Nano silver solution did not affect the characters measured. On the basis of the data obtained in this experiment, it was concluded that NS had a good potential for removing of the bacterial contaminants in plant tissue culture procedures. As this is the first report on application of NS in in vitro culture techniques, further investigations on other plant species are needed to clarify the effectiveness of NS for the removal of bacterial contaminants in tissue culture of other crops.     

Isolation of the inner acrosomal-nuclear membrane complex from rabbit spermatozoa

Rabbit spermatozoa were passed through a Bio-Glas 2500 (BG) column to yield pure cytoplasmic droplets and consequently the droplet-free spermatozoa. Rapid decondensation of sperm nuclei was achieved by 1 mM dithiothreitol (DTT) and 1.5 M NaCl. This treatment caused removal of the plasma and the outer acrosomal membranes. The viscosity of decondensed nuclei was reduced by pancreatic DNase. Further elution of the suspension from BG column yielded a membrane complex. On the basis of electron microscopic observations and the enzyme analysis, these membranes appeared to be the inner acrosomal-nuclear membrane complex (IANC). The IANC was also prepared from isolated sperm head by DTT-NaCl and Dnasetreatment and low-speed centrifugation.     

Systematic analysis of gut microbiome reveals the role of bacterial folate and homocysteine metabolism in Parkinson’s disease

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Comparative inflorescence and floral ontogeny in the genus Mentha (Mentheae: Nepetoideae: Lamiaceae): variable sequences of organ appearance and random petal aestivation

The genus Mentha is a taxonomically complex genus, characterized by large morphological variations. Only a few, frequently overlapping, characters are of value in taxonomy. Comparative floral developmental studies provide an opportunity for better understanding the systematic relationships among different species. The inflorescence and floral ontogeny of three Mentha L. species (M. piperita L., M. pulegium L. and M. suaveolens Ehrh.) were investigated using epi-illumination light microscopy. All three species studied have thyrses with the same developmental pathway. The lack of higher order bracts and the monochasial branching of the higher order inflorescence apices were found as special features of inflorescence ontogeny. Sepals appear unidirectionally from the adaxial side in all except for M. pulegium which shows a modified unidirectional sequence. Variable sequences of petal and stamen appearance from unidirectional to reversed unidirectional sequence are present in all. Significant ontogenetic features include (1) appearance of the corolla as a rim before petal lobes become visible and (2) instability in petal aestivation. Morphological features including densely hairy calyx, five-lobed corolla tube, smaller adaxial stamens and hairy ovary with included style distinguish M. pulegium from the other species. On the basis of our results floral ontogenetic features could be considered important characters for delimiting or diagnosing different sections in the genus Mentha. Variable sequences of petal lobe appearance and instability in petal aestivation were found as unusual developmental characters.