Toxoplasma gondii: Reproductive parameters in experimentally infected male rats

Toxoplasma gondii is a protozoan parasite that is globally widespread and infects man and animals. With the aim of studying the influence of toxoplasmosis on male reproductive parameters, we investigated sperm motility, concentration and morphology of male rats experimentally infected by T. gondii. The GT F1 strain of T. gondii tissue cysts were fed at a dose of 5 × 10³ tissue cysts per rat by oral gavage in an experimental group of 42 healthy adult male Wistar rats, while 42 male rats were used as controls. On days 10, 20, 30, 40, 50 and 60 post-inoculation (p.i.) 7 rats from each group were anesthetized. The body weight of each animal was recorded, then epididymis and testes were immediately removed, weighed and semen evaluation was undertaken. Weight of the right epididymis was significantly decreased on day 30 p.i., sperm motility was significantly decreased on days 10, 20, 30, 40, 50 and 60 p.i. and sperm concentration was significantly decreased on days 10, 30, 40 and 60 p.i. A marked increase of sperm abnormalities was noticed on days 30 and 40 p.i. No pathological lesions were detected either in the pituitary gland or the testes. In this study it was found that toxoplasmosis can affect main reproductive parameters in male rats, which are the most predictive of their fertilizing capacity.     

Optimized Null Model for Protein Structure Networks

Much attention has recently been given to the statistical significance of topological features observed in biological networks. Here, we consider residue interaction graphs (RIGs) as network representations of protein structures with residues as nodes and inter-residue interactions as edges. Degree-preserving randomized models have been widely used for this purpose in biomolecular networks. However, such a single summary statistic of a network may not be detailed enough to capture the complex topological characteristics of protein structures and their network counterparts. Here, we investigate a variety of topological properties of RIGs to find a well fitting network null model for them. The RIGs are derived from a structurally diverse protein data set at various distance cut-offs and for different groups of interacting atoms. We compare the network structure of RIGs to several random graph models. We show that 3-dimensional geometric random graphs, that model spatial relationships between objects, provide the best fit to RIGs. We investigate the relationship between the strength of the fit and various protein structural features. We show that the fit depends on protein size, structural class, and thermostability, but not on quaternary structure. We apply our model to the identification of significantly over-represented structural building blocks, i.e., network motifs, in protein structure networks. As expected, choosing geometric graphs as a null model results in the most specific identification of motifs. Our geometric random graph model may facilitate further graph-based studies of protein conformation space and have important implications for protein structure comparison and prediction. The choice of a well-fitting null model is crucial for finding structural motifs that play an important role in protein folding, stability and function. To our knowledge, this is the first study that addresses the challenge of finding an optimized null model for RIGs, by comparing various RIG definitions against a series of network models.     

Stereocontrolled Facile Synthesis and Biological Evaluation of (3′S) and (3′R)-3′-Amino (and Azido)-3′-Deoxy Pyranonucleosides

This article describes the synthesis of (3 ′S) and (3 ′R)-3 ′-amino-3 ′-deoxy pyranonucleosides and their precursors (3 ′S) and (3 ′R)-3 ′-azido-3 ′-deoxy pyranonucleosides. Azidation of 1,2:5,6-di-O-isopropylidene-3-O-toluenesulfonyl-α-D-allofuranose followed by hydrolysis and subsequent acetylation afforded 3-azido-3-deoxy-1,2,4,6-tetra-O-acetyl-D-glucopyranose, which upon coupling with the proper silylated bases, deacetylation, and catalytic hydrogenation, obtained the target 3 ′-amino-3 ′-deoxy-β-D-glucopyranonucleosides. The desired 1-(3 ′-amino-3 ′-deoxy-β-D-allopyranosyl)5-fluorouracil was readily prepared from the suitable imidazylate sugar after azidation followed by a protection/deprotection sequence and reduction of the unprotected azido precursor. No antiviral activity was observed for the novel nucleosides. Moderate cytostatic activity was recorded for the 5-fluorouracil derivatives.     

Chiral Separation of the Clinically Important Compounds Fucose and Pipecolic Acid Using CE: Determination of the Most Effective Chiral Selector

In this study, simple electrophoretic methods were developed for the chiral separation of the clinically important compounds fucose and pipecolic acid. In recent years, these analytes, and particularly their individual enantiomers, have attracted considerable attention due to their role in biological functions and disorders. The detectability and sensitivity of pipecolic acid and fucose were improved by reacting them with fluorenylmethyloxycarbonyl chloride (FMOC‐Cl) and 5‐amino‐2‐naphthalene‐sulfonic acid (ANSA), respectively. The enantioseparation conditions were optimized by initially investigating the type of the chiral selector. Different chiral selectors, such as polymeric surfactants and cyclodextrins, were used and the most effective ones were determined with regard to resolution and analysis time. A 10‐mM β‐cyclodextrin was able to separate the enantiomers of ANSA‐DL‐fucose and the polymeric surfactant poly(sodium N‐undecanoyl‐LL‐leucine‐valinate) was able to separate the enantiomers of FMOC‐DL‐pipecolic acid, with resolution values of 3.45 and 2.78, respectively. Additional parameters, such as the concentration and the pH of the background electrolyte (BGE), the concentration of the chiral selector, and the addition of modifiers were examined in order to optimize the separations. The addition of the chiral ionic liquid D‐alanine tert‐butyl ester lactate into the BGE was also investigated, for the first time, in order to improve resolution of the enantiomers. Chirality 25:556–560, 2013. © 2013 Wiley Periodicals, Inc.     

Effects of exogenous l-arginine on in vitro rooting, chlorophyll, carbohydrate, and proline concentrations in the sweet cherry rootstock M × M 14 (Prunus avium L. × Prunus mahaleb L.)

The effects of indole-3-butyric acid (IBA) alone and in combination with l-arginine on the morphogenic and biochemical responses in shoot tip explants of the cherry rootstock M × M 14 (Prunus avium × Prunus mahaleb) were examined. The maximum root number per rooted explant (16), root fresh (FW) and dry (DW) weights, as well as the rooting percentage (100 %) were recorded when 2 mg l^?1 IBA (alone) were applied. Including the lowest IBA concentration (0.5 mg l^?1) with the lowest and highest l-arginine concentrations (0.5 and 2 mg l^?1, respectively) resulted in the greatest root length. The maximum leaf chlorophyll concentration and shoot length of the initial explant were recorded when 0.5 mg l^?1 IBA plus 2 mg l^?1 l-arginine were applied. In addition, l-arginine in combination with IBA (1 and 2 mg l^?1) was found to suppress shoot FW and DW. On the other hand, l-arginine enhanced the promoting effect of IBA on both root length and leaf chlorophyll concentration. The carbohydrate and proline concentrations in leaves were not significantly altered with the application of IBA alone or in combination with l-arginine. On the other hand, the carbohydrate and proline concentrations in roots were decreased with the application of 1 and 2 mg l^?1 IBA with l-arginine, resulting in the suppression of the promoting effects of IBA. It is clear from the findings that l-arginine has a direct effect on the in vitro rooting of M × M 14 explants, is involved in the function of the photosythetic apparatus, influences leaf chlorophyll content, participates in carbohydrate biosynthesis and metabolism, and is involved in proline accumulation both in leaves and roots.     

Impact of <Emphasis Type="Italic">Populus</Emphasis> Plantations on Water and Soil Quality

Trees of genus Populus (in our context primarily poplars) are predominantly grown in Sweden in small plantations on arable land in southern and central parts of the country to produce biomass for energy and other purposes. This study evaluated the effects (i) of poplar plantations on groundwater quality, by determining differences in leaching of nitrogen and phosphorus to groundwater, and (ii) of poplar and hybrid aspen plantations on soil quality in terms of carbon in the top- and subsoil. The study was conducted comparing Populus plantations in Sweden with adjacent fields with cereals and grasslands. The experiment concerning the groundwater leaching was conducted in eight poplar plantations along three growing seasons (2012–2015). For the soil carbon experiments, 19 poplar and two hybrid aspen plantations and the respective reference fields were sampled. NO₃-N leaching from poplar plantations was significantly lower than that from reference fields with cereals, but not when compared with grasslands. Spring NO₃-N leaching was significantly lower in poplars than in the reference fields, whereas leaching of NO₃-N in autumn did not differ. Concentrations of PO₄-P in the groundwater of poplar plantations were lower compared to the respective ones of the reference fields. There were no clear trends observed when comparing carbon concentrations in the topsoil of the poplar and hybrid aspen plantations compared to the respective adjacent reference fields. For the subsoil, the average carbon concentrations in the poplar and hybrid aspen plantations were equal to the respective ones of cereals, but were higher when compared to grassland.