Maternal Plasma and Amniotic Fluid Sphingolipids Profiling in Fetal Down Syndrome

IntroductionSphingolipids can be potentially involved in the formation of the central and peripheral nervous systems, which are particularly connected with the pathogenesis of Down syndrome. The aim of the study was to determine the concentration of selected sphingolipids in the plasma and amniotic fluid of pregnant patients with fetal Down syndrome.ResultsWe showed a significant increase in the concentration of 2 ceramides, C22-Cer and C24:1-Cer, in the plasma of women with fetal Down syndrome. Furthermore we showed a decrease in the concentration of 7 ceramides—C16-Cer, C18-Cer, C18:1-Cer, C20-Cer, C22-Cer, C24:1-Cer, and C24-Cer—in the amniotic fluid of women with fetal Down syndrome. We created ROC curves for all significant sphingolipids in maternal plasma, which set the threshold values and allowed for predicting the likelihood of Down syndrome in the fetus with specific sensitivity and specificity. We demonstrated a significantly higher risk of Down syndrome when the plasma concentration of C22-Cer > 12.66 ng/100ul (sens. 0.9, sp. 0.79, P value = 0.0007) and C24:1-Cer > 33,19 ng/100ul (sens. 0.6, sp. 0.86, P value = 0.0194).ConclusionOn the basis of our findings, it seems that the sphingolipids may play a role in the pathogenesis of Down syndrome. Defining their potential as biochemical markers of Down syndrome requires further investigation on a larger group of patients.     

Heterologous expression of the isopimaric acid pathway in <Emphasis Type="Italic">Nicotiana benthamiana</Emphasis> and the effect of N-terminal modifications of the involved cytochrome P450 enzyme

Background

Plant terpenoids are known for their diversity, stereochemical complexity, and their commercial interest as pharmaceuticals, food additives, and cosmetics. Developing biotechnology approaches for the production of these compounds in heterologous hosts can increase their market availability, reduce their cost, and provide sustainable production platforms. In this context, we aimed at producing the antimicrobial diterpenoid isopimaric acid from Sitka spruce. Isopimaric acid is synthesized using geranylgeranyl diphosphate as a precursor molecule that is cyclized by a diterpene synthase in the chloroplast and subsequently oxidized by a cytochrome P450, CYP720B4.

Results

We transiently expressed the isopimaric acid pathway in Nicotiana benthamiana leaves and enhanced its productivity by the expression of two rate-limiting steps in the pathway (providing the general precursor of diterpenes). This co-expression resulted in 3-fold increase in the accumulation of both isopimaradiene and isopimaric acid detected using GC-MS and LC-MS methodology. We also showed that modifying or deleting the transmembrane helix of CYP720B4 does not alter the enzyme activity and led to successful accumulation of isopimaric acid in the infiltrated leaves. Furthermore, we demonstrated that a modified membrane anchor is a prerequisite for a functional CYP720B4 enzyme when the chloroplast targeting peptide is added. We report the accumulation of 45–55 μg/g plant dry weight of isopimaric acid four days after the infiltration with the modified enzymes.

Conclusions

It is possible to localize a diterpenoid pathway from spruce fully within the chloroplast of N. benthamiana and a few modifications of the N-terminal sequences of the CYP720B4 can facilitate the expression of plant P450s in the plastids. The coupling of terpene biosynthesis closer to photosynthesis paves the way for light-driven biosynthesis of valuable terpenoids.

     

Homodimerization propensity of the intrinsically disordered N-terminal domain of Ultraspiracle from Aedes aegypti

The mosquito Aedes aegypti is the principal vector of dengue, one of the most devastating arthropod-borne viral infections in humans. The isoform specific A/B region, called the N-terminal domain (NTD), is hypervariable in sequence and length and is poorly conserved within the Ultraspiracle (Usp) family. The Usp protein together with ecdysteroid receptor (EcR) forms a heterodimeric complex. Up until now, there has been little data on the molecular properties of the isolated Usp-NTD. Here, we describe the biochemical and biophysical properties of the recombinant NTD of the Usp isoform B (aaUsp-NTD) from A. aegypti. These results, in combination with in silico bioinformatics approaches, indicate that aaUsp-NTD exhibits properties of an intrinsically disordered protein (IDP). We also present the first experimental evidence describing the dimerization propensity of the isolated NTD of Usp. These characteristics also appear for other members of the Usp family in different species, for example, in the Usp-NTD from Drosophila melanogaster and Bombyx mori. However, aaUsp-NTD exhibits the strongest homodimerization potential. We postulate that the unique dimerization of the NTD might be important for Usp function by providing an additional platform for interactions, in addition to the nuclear receptor superfamily dimerization via DNA binding domains and ligand binding domains that has already been extensively documented. Furthermore, the unique NTD–NTD interaction that was observed might contribute new insight into the dimerization propensities of nuclear receptors.     

Caucalido platycarpi-Vicietum michauxii — a new weed association from crop fields of Kyrgyzstan (Middle Asia)

The study presents the results of geobotanical investigations conducted in crop fields in the western Tian Shan Mts in Kyrgyzstan (Middle Asia). The main research focused on classification of weed communities developing within this poorly investigated area, were conducted in the vicinity of Bishkek and Kara-Balta in 2010. Altogether, 299 phytosociological relevés were sampled using the Braun-Blanquet method. Based on all segetal vegetation patches, the analyses distinguished a new association: Caucalido platycarpi-Vicietum michauxii. The results of these phytosociological studies fill a gap in the knowledge about the syntaxonomical diversity of the Middle Asia region, which is one of the most crucial for segetal weed species. The study shows that anthropogenic agrocoenoses could harbour relatively rich flora. Extensively cultivated fields could especially serve as a suitable habitat for many xerothermophilous and heliophilous plants. More than 75 species in vegetation plots, mainly permament weeds, have been found. There is also a considerable share of species coming over from swards, screes and meadows.     

Epigenetic modifications of nuclei differ between root meristematic tissues of Hordeum vulgare

Recent studies on the role of epigenetic modifications during plant development emphasize the fact that both positional information and tissue specificity are essential factors that establish epigenetic marks and thus determine cell fate and differentiation processes. The root apical meristem (RAM), which contains stem cells and generates radial patterns of tissues, is an ideal model for studying the correlation between cell position and cell-type differentiation, with particular emphasis on the patterns, global levels, and landscapes of epigenetic modifications. To date, there has been no clear evidence for differential levels of histone and DNA modification across root meristematic tissues. Our study clearly indicates that levels of modifications with potential epigenetic effects vary between RAM tissues. Of particular interest is that histone H4 acetylation in the epidermis is not simply replication-dependent and probably plays a role in epidermal cell differentiation.     

Monte Carlo simulations of a polymer chain conformation. The effectiveness of local moves algorithms and estimation of entropy

A linear chain on a simple cubic lattice was simulated by the Metropolis Monte Carlo method using a combination of local and non-local chain modifications. Kink-jump, crankshaft, reptation and end-segment moves were used for local changes of the chain conformation, while for non-local chain rearrangements the "cut-and-paste" algorithm was employed. The statistics of local micromodifications was examined. An approximate method for estimating the conformational entropy of a polymer chain, based on the efficiency of the kink-jump motion respecting chain continuity and excluded volume constraints, was proposed. The method was tested by calculating the conformational entropy of the undisturbed chain, the chain under tension and in different solvent conditions (athermal, theta and poor) and also of the chain confined in a slit. The results of these test calculations are qualitatively consistent with expectations. Moreover, the obtained values of the conformational entropy of self avoiding chain with ends fixed over different separations, agree very well with the available literature data.

Ab initio predictions of structural and elastic properties of struvite: contribution to urinary stone research

In the present work, we carried out density functional calculations of struvite – the main component of the so-called infectious urinary stones – to study its structural and elastic properties. Using a local density approximation and a generalised gradient approximation, we calculated the equilibrium structural parameters and elastic constants C _ijkl . At present, there is no experimental data for these elastic constants C _ijkl for comparison. Besides the elastic constants, we also present the calculated macroscopic mechanical parameters, namely the bulk modulus (K), the shear modulus (G) and Young's modulus (E). The values of these moduli are found to be in good agreement with available experimental data. Our results imply that the mechanical stability of struvite is limited by the shear modulus, G. The study also explores the energy-band structure to understand the obtained values of the elastic constants.     

Targeted endoradiotherapy using nucleotides

Increased cellular proliferation is an integral part of the cancer phenotype. Hence, the sustained and continued demand on supply of DNA building blocks during the DNA replication presents a potential target for therapeutic intervention. For this propose, the α and Auger electron emitting nucleotides analogs are attractive for targeted endoradiotherapy, given that DNA of malignant cells is selectively addressed. This review summarizes development and preclinical and clinical studies of endoradiotherapeutic acting nucleoside analogs with a special focus on thymidine analogs.