Electrophysiological correlates activated during the Wisconsin Card Sorting Test (WCST)

In the present study we investigated changes in Event-Related Potentials (ERPs) during the Wisconsin Card Sorting Test (WCST) in order to identify cognitive processes underlying the set-shifting aspects of the task and to determine test sensitivity for frontal and prefrontal cortical areas. ERP's were recorded from a sample of 20 healthy adults while they performed a computerized version of the Grant & Berg (1948) version of the WCST, using 32-channel electroencephalogram recordings. The ERP waveforms were calculated for the set-shifting trials, or more precisely for the 2nd and the 3rd trials in the WCST series (set change condition) and compared to those associated with the last two trials in a series before the set change (set unchanged condition). The results indicated changes in central frontal and parietal electrodes during attentional set-shifting. More precisely, the P300 effect was replicated in this dataset, confirming the claim that the WCST measures function of prefrontal cortical areas of the brain. However, the obtained wave resembled P3b indicating the working memory component of the task. The results suggest that the frontal and parietal cortical activity is especially involved in set-shifting during WCST performance. Therefore, these electrophysiological results are not consistent with some recent studies that question the specificity of WCST as a measure of frontal and parietal lesions.     

Calmodulin and S100A1 protein interact with N terminus of TRPM3 channel

Transient receptor potential melastatin 3 ion channel (TRPM3) belongs to the TRP family of cation-permeable ion channels involved in many important biological functions such as pain transduction, thermosensation, and mechanoregulation. The channel was reported to play an important role in Ca(2+) homeostasis, but its gating mechanisms, functions, and regulation are still under research. Utilizing biophysical and biochemical methods, we characterized two independent domains, Ala-35-Lys-124 and His-291-Gly-382, on the TRPM3 N terminus, responsible for interactions with the Ca(2+)-binding proteins calmodulin (CaM) and S100A1. We identified several positively charged residues within these domains as having a crucial impact on CaM/S100A1 binding. The data also suggest that the interaction is calcium-dependent. We also performed competition assays, which suggested that CaM and S100A1 are able to compete for the same binding sites within the TRPM3 N terminus. This is the first time that such an interaction has been shown for TRP family members.     

CYP90A1/CPD, a Brassinosteroid Biosynthetic Cytochrome P450 of Arabidopsis, Catalyzes C-3 Oxidation

Brassinosteroids (BRs) are steroidal phytohormones that regulate plant growth and development. Whereas in Arabidopsis the network-like routes of BR biosynthesis have been elucidated in considerable detail, the roles of some of the biosynthetic enzymes and their participation in the different subpathways remained to be clarified. We investigated the function of the cytochrome P450 monooxygenase CYP90A1/CPD, which earlier had been proposed to act as a BR C-23 hydroxylase. Our GC-MS and genetic analyses demonstrated that the cpd mutation arrests BR synthesis upstream of the DET2-mediated 5α reduction step and that overexpression of the C-23 hydroxylase CYP90C1 does not alleviate BR deficiency in the cpd mutant. In line with these results, we found that CYP90A1/CPD heterologously expressed in a baculovirus-insect cell system catalyzes C-3 oxidation of the early BR intermediates (22S)-22-hydroxycampesterol and (22R,23R)-22,23-dihydroxycampesterol, as well as of 6-deoxocathasterone and 6-deoxoteasterone. Enzyme kinetic data of CYP90A1/CPD and DET2, together with those of the earlier studied CYP90B1, CYP90C1, and CYP90D1, suggest that BR biosynthesis proceeds mainly via the campestanol-independent pathway.     

Induction of oxidative stress, lysosome activation and autophagy by nanoparticles in human brain-derived endothelial cells

Different types of NPs (nanoparticles) are currently under development for diagnostic and therapeutic applications in the biomedical field, yet our knowledge about their possible effects and fate in living cells is still limited. In the present study, we examined the cellular response of human brain-derived endothelial cells to NPs of different size and structure: uncoated and oleic acid-coated iron oxide NPs (8-9 nm core), fluorescent 25 and 50 nm silica NPs, TiO2 NPs (21 nm mean core diameter) and PLGA [poly(lactic-co-glycolic acid)]-PEO [poly(ethylene oxide)] polymeric NPs (150 nm). We evaluated their uptake by the cells, and their localization, generation of oxidative stress and DNA-damaging effects in exposed cells. We show that NPs are internalized by human brain-derived endothelial cells; however, the extent of their intracellular uptake is dependent on the characteristics of the NPs. After their uptake by human brain-derived endothelial cells NPs are transported into the lysosomes of these cells, where they enhance the activation of lysosomal proteases. In brain-derived endothelial cells, NPs induce the production of an oxidative stress after exposure to iron oxide and TiO2 NPs, which is correlated with an increase in DNA strand breaks and defensive mechanisms that ultimately induce an autophagy process in the cells.     

Oostatic peptides containing <Emphasis Type="SmallCaps">d</Emphasis>-amino acids: synthesis,oostatic activity,degradation, accumulation in ovaries and NMR study

Analogs of the H-Tyr-Asp-Pro-Ala-Pro-OH pentapeptide with d-amino acid residues either in differing or in all of the positions of the sequences were prepared and their oostatic potency was compared with that of the parent pentapeptide. The d-amino acid residue containing analogs exhibited an equal or even higher oostatic effect in the flesh fly Neobellieria bullata than the parent peptide. Contrary to the rapid incorporation of radioactivity from the labeled H-Tyr-Asp-[³H]Pro-Ala-Pro-OH pentapeptide into the ovaries of N. bullata in vitro, the radioactivity incorporation from the labeled pentapeptides with either d-aspartic acid or d-alanine was significantly delayed. As compared to the parent pentapeptide, also the degradation of both the d-amino acid-containing analogs mentioned above proceeded at a significantly lower rate. The decreased intake of radioactivity, the lower degradation and finally also the high oostatic effect may be ascribed to the decreased enzymatic degradation of the peptide bonds neighboring the d-amino acid residues in the corresponding peptides. The introduction of the non-coded d-amino acids thus enhances the oostatic effect in N. bullata owing to the prolonged half-life of the corresponding pentapeptides, which can thus affect more ovarian cells.     

Ectopic dermal ridge configurations on the interdigital webbings and postaxial marginal portion of the hindlimb in Hammertoe mutant mice (Hm)

The effects of the hereditary malformation of Hammertoe mutant mice (gene symbol Hm) on the digital pads and dermal ridge configurations on their hindlimbs were examined. In the wild‐type (+/+) mice with normally separated digits, dermal ridges developed only on the pads. Heterozygous (Hm/+) and homozygous (Hm/Hm) mutant mice, however, had a broad big toe, fused interdigital soft tissues, reduced claws, an extra rudimentary postaxial digit and camptodactyly. The dermal ridges appeared not only on the pads, affected in their number and configurations, but also on the ventral surface of the interdigital webbings and postaxial marginal area exhibiting an extra rudimentary digit and webbing. These aberrant configurations may be related to the abnormal occurrence of programmed cell death (PCD) in the interdigital zones and the postaxial marginal portion in Hm/+ and Hm/Hm mice. That is, the diminished cell death may fail to decrease the cell density in the interdigital zones and postaxial marginal portion and result in the webbing and an extra rudimentary digit and webbing, respectively. Simultaneously, it could also interrupt the migration of surviving cells of these areas toward the neighboring digits and the distal area of the sole and produce the ectopic dermal ridges on the way to the as yet unformed (presumptive) digital and plantar volar pads. The present findings suggest that normal interdigital and pre/postaxial PCD contributes not only to the separation of digits, the initial formation of individual digits of different sizes, and the inhibition of the extra digit but also to the development of the presumptive digital and plantar pads, including dermal ridges. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.     

Newly resolved relationships in an early land plant lineage: Bryophyta class Sphagnopsida (peat mosses)

? Premise of the study: The Sphagnopsida, an early-diverging lineage of mosses (phylum Bryophyta), are morphologically and ecologically unique and have profound impacts on global climate. The Sphagnopsida are currently classified in two genera, Sphagnum (peat mosses) with some 350-500 species and Ambuchanania with one species. An analysis of phylogenetic relationships among species and genera in the Sphagnopsida were conducted to resolve major lineages and relationships among species within the Sphagnopsida. ? Methods: Phylogenetic analyses of nucleotide sequences from the nuclear, plastid, and mitochondrial genomes (11 704 nucleotides total) were conducted and analyzed using maximum likelihood and Bayesian inference employing seven different substitution models of varying complexity. ? Key results: Phylogenetic analyses resolved three lineages within the Sphagnopsida: (1) Sphagnum sericeum, (2) S. inretortum plus Ambuchanania leucobryoides, and (3) all remaining species of Sphagnum. Sister group relationships among these three clades could not be resolved, but the phylogenetic results indicate that the highly divergent morphology of A. leucobryoides is derived within the Sphagnopsida rather than plesiomorphic. A new classification is proposed for class Sphagnopsida, with one order (Sphagnales), three families, and four genera. ? Conclusions: The Sphagnopsida are an old lineage within the phylum Bryophyta, but the extant species of Sphagnum represent a relatively recent radiation. It is likely that additional species critical to understanding the evolution of peat mosses await discovery, especially in the southern hemisphere.     

Efficiency of different methods of extraction and purification of cytokinins

The increasing use of advanced methods, such as mass spectrometry, for the determination of cytokinins has raised special requirements for the extraction and purification of this class of plant hormones. Extraction of Arabidopsis thaliana plants with three different solvents, [80% (v/v) MeOH, Bieleski's MCF-7, and modified Bieleski's] provided similar yields of most analyzed cytokinins determined by high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS). However, the extraction with a modified Bieleski's solvent (MeOH-HCO2H-H2O [15:1:4, v/v/v]) gave the highest responses of deuterated cytokinins (used as test compounds) in plant extracts as compared to the responses of pure deuterated standards (relative internal standard response, RISR). Purification of cytokinins using Oasis MCX sorbent with reversed-phase and cation-exchange characteristics, in comparison to the DEAE Sephadex RP-C18 method, provided higher levels of zeatin riboside monophosphate and similar levels of cytokinin bases, ribosides and glucosides. Using this method the content of UV-absorbing contaminates was decreased by about 90% and the RISR values of all tested cytokinin standards but riboside monophosphates were increased about two-fold. The former method provided preparations more suitable for HPLC/MS/MS analysis with respect to simplicity and sample purity.