Kinetic models for the dynamical behavior of polyacrylamide (PAAm)–κ-carrageenan (κC) composite gels

A fluorescence method was employed for studying the drying and swelling of PAAm–κC composite gels, which were formed from acrylamide (AAm) and N, N’- methylenebisacrylamide (BIS) with various κ–carrageenan (κC) contents by free radical crosslinking copolymerization in water. Composite gels were prepared at 80 °C with pyranine (Py) as a fluorescence probe. Scattered light, I_sc, and fluorescence emission intensities, I_em, were monitored during drying and swelling of these gels. The fluorescence intensity of pyranine increased and decreased as drying and swelling time are increased, respectively, for all gel samples. The Stern–Volmer equation combined with moving boundary and Li-Tanaka models were used to explain the behavior of I_em during drying and swelling processes respectively. It is found that the desorption coefficient D_d decreased as κC contents were increased for a given temperature during drying. However, the cooperative diffusion coefficient, D_s presented exactly the opposite case. Conventional gravimetrical and volumetric experiments were also carried out during drying and swelling of PAAm–κC composite gels. It was observed that D_d and D_s values measured with the fluorescence method were found to be much larger than they were measured with the conventional methods.     

Rheology and synergy of κ-carrageenan/locust bean gum/konjac glucomannan gels

The rheology and melting of mixed polysaccharide gels containing konjac glucomannan (KGM), locust bean gum (LBG) and κ-carrageenan (KC) were studied. Synergy-type peaks in the Young's modulus at optimal mixing ratios were found for both KC/LBG and KC/KGM binary gels at a fixed total polysaccharide content (1:5.5 for LBG:KC and 1:7 for KGM:KC). The Young's modulus peak for KC/KGM was higher than for KC/LBG gels. The same stoichiometric mixing ratios were found when either LBG or KGM was added to KC at a fixed KC concentration, where the Young's modulus increased up to additions at the stoichiometric ratio, but leveled off at higher LBG or KGM additions. Addition of KGM or LBG to the 2-component gels beyond the stoichiometric (optimal) mixing ratio at a fixed total polysaccharide content led to a decrease in the Young's modulus and an increase in the rupture strain and stress in extension, and both trends were stronger for KGM than for LBG.     

Identification of the site of glycation of γ-II-crystallin by (14C)-fructose

Cataract formation in diabetes may be via non-enzymic glycosylation (glycation) of lens proteins due to increased concentrations of sugars present in the lenses of diabetic patients. The objective of this project was to identify the site(s) of glycation of bovine γ-II-crystallin by [¹⁴C]fructose. γ-II-crystallin was isolated from soluble lens nucleus proteins by gel chromatography, followed by ion-exchange chromatography and was then glycated by incubation with [¹⁴C]fructose. Radioactively labelled γ-II-crystallin was cleaved with trypsin. Affinity chromatography of the tryptic peptides gave a single main peak containing the majority of the radioactivity. This indicated that fructose had reacted at a single site on the protein. Amino acid analysis of this peptide showed it to contain only lysine and a trace amount of glycine. By relating the results of the amino acid analysis to the amino acid sequence of γ-II-crystallin, it was concluded that the labelled peptide corresponded to the N-terminal dipeptide. The site of glycation of bovine γ-II-crystallin by fructose was thereby identified as the α-NH₂ group of the N-terminal glycine.     

Characteristics of catchments disturbed by lignite mining—case study of Schlabendorf/Seese (Germany)

In the Lower Lusatian lignite mining district, large areas have been mined and recultivated. An even larger area has been affected by groundwater lowering. The specific characteristics of catchments disturbed by lignite mining are presented for the Schlabendorf/Seese region, where a close relation between water issues and open-cast lignite mining exists. In general, this relationship starts prior to mining and persists even after the land is reclaimed.The most obvious feature of this post-mining landscape is the large number of forming post-mining lakes. A further feature is the recovery of the groundwater table. Dry streams and springs now are starting to flow again, and areas with a formerly deep groundwater table are now directly influenced by rising groundwater.The disturbance causes various acidification phenomena. The aeration of pyrite-bearing material leads to a drastic deterioration of the groundwater quality, which affects receiving streams and lakes. Thus there is the tendency for some parts of post-mining lakes to become acid. Additionally, in the marginal areas of the groundwater recovery, acidification of streams occurs, causing water quality problems in ponds and lakes located downstream.The development of each individual water body with respect to water quantity and quality depends on its specific hydrogeological and hydrological setting. The region is experiencing dynamic changes, and shows that the future development of the post-mining catchments is difficult to predict.     

Reversal of obesity-induced hypertriglyceridemia by (R)-α-lipoic acid in ZDF (fa/fa) rats

Controlling elevated blood triacylglycerol translates into substantial health benefits. The present study aimed to evaluate the triacylglycerol-lowering properties of (R)-α-lipoic acid (LA) once circulating triacylglycerol levels have become elevated, and identify the molecular targets of LA. Nine-week old male ZDF (fa/fa) rats were fed a chow diet supplemented with 3 g LA per kg diet or pair fed for two weeks (8 rats per treatment). We determined changes in blood triacylglycerol, insulin, non-esterified fatty acids, and ketone bodies concentrations. We analyzed the expression of genes and proteins involved in fatty acid and triacylglycerol metabolism in liver, epididymal fat, and skeletal muscle. Feeding LA to ZDF rats (a) corrected severe hypertriglyceridemia, (b) lowered abdominal fat mass, (c) raised circulating fibroblast growth factor-21 and Fgf21 liver gene expression, (d) repressed lipogenic gene expression of ATP-citrate synthase (Acly), acetyl-coA carboxylase 1 (Acaca), fatty acid synthase (Fasn), sn-glycerol-3-phosphate acyltransferase 1 (Gpam), adiponutrin (Pnpla3) in the liver and adipose tissue, (e) decreased hepatic protein levels of ACC1/2, FASN and 5′-AMP-activated protein kinase catalytic subunit α (AMPKα), (f) did not change phospho-AMPKα/AMPKα and phospho-ACC/ACC ratios, (g) stimulated liver gene expression of PPARα target genes carnitine O-palmitoyltransferase 1β (Cpt1b) and acyl-CoA thioesterase 1 (Acot1) but not carnitine O-palmitoyltransferase 1α (Cpt1a). This is evidence that short-term LA feeding to obese rats reverses severe hypertriglyceridemia. FGF21 may mediate the beneficial metabolic effects of LA.     

Microbial functionalization of (–)-ambroxide by filamentous fungi

Abstract

Biocatalysis is a very useful tool for organic chemists to functionalize organic compounds under working conditions milder than chemical ones. This methodology has special significance since it can be an easy way to introduce a functional group in a non-reactive carbon, regio- and stereoselectively. In order to look for new compounds with antioxidant activity we report the transformation of the natural substrate (–)-ambroxide using the enzyme potential of pure strains of the filamentous fungi Alternaria alternata and Cunninghamella sp., following a protocol with growing cell cultures, which produced the new compound 1β-hydroxyambroxide and the previously known compound 3β-hydroxyambroxide. After purification their structures were elucidated by spectroscopic methods. These two metabolites are the products of oxidation of ring A of the starting material, without evidence of other compounds with different functionalization. Both compounds were tested for their activity as free radical scavengers in vitro, using the assay of DPPH (1,1-diphenyl-2-picrylhydrazyl) radical trapping. The results demonstrated that hydroxylation of carbons C-1 and C-3 of (–)-ambroxide with β stereochemistry had no effect on biological activity as an antioxidant compared with the starting material and a reference substance.     

Molecular-weight estimates of milk-fat-globule-membrane protein–sodium dodecyl sulphate complexes by electrophoresis in gradient acrylamide gels

The molecular weights of milk-fat-globule-membrane proteins solubilized in sodium dodecyl sulphate were estimated by gradient gel electrophoresis. Standard curves were calibrated from both protein and glycoprotein markers of known molecular weight. Six major proteins were observed with Coomassie Blue staining and six with periodic acid-Schiff staining. The behaviour of the membrane proteins and the marker proteins was compared on several different single strength sodium dodecyl sulphate-polyacrylamide gels between 3 and 12% (w/v). The results were used to calculate the free electrophoretic mobility and retardation coefficient of each protein. Glycoprotein markers had a significantly lower mean free electrophoretic-mobility value than the protein markers. Three of the milk-fat-globule-membrane glycoproteins were shown to be independent of any of the Coomassie Blue-stained bands. On the basis of a comparison of the free electrophoretic-mobility and retardation- coefficient values of markers and unknown proteins the most appropriate standard curve for molecular-weight estimation was chosen.     

Biotransformation of (±)-2-methylcyclohexanone by fungi

The biotransformation of 2-methylcyclohexanone (1) using 16 fungal strains and some mushroom cultures was investigated. Fusarium sp. was one of the effective biocatalysts for oxidoreduction of 2-methylcyclohexanone (1). cis-2-Methylcyclohexanol (2a) was isomerized to trans-2-methylcyclohexanol (2b) by Fusarium sp. In addition, the corresponding lactones 3 was obtained by Baeyer-Villiger oxidation using Fusarium sp. AP-2 (46%, 94% ee).     

Photocatalysis of chloroform degradation by μ-dichlorotetrachlorodipalladate(II)

Unlike other chlorometallate complexes that catalyze the photodecomposition of haloalkanes through photodissociation of a chlorine atom, both and catalyze chloroform decomposition through a process that appears to involve C-H bond breakage from an excited state association complex with chloroform. This would account for the greatly retarded rate of decomposition in CDCl₃ and for the generation of CCl₄ as a side product. In chloroform, and are in slow equilibrium with each other. The rate for the conversion of - in chloroform at 23 °C obeys the expression (0.03 M⁻¹ s⁻¹) [][Cl⁻]. The equilibrium constant, K = [][Cl⁻]²/[]², was estimated to be 3 × 10⁻³ M in CHCl₃.     

Theoretical investigation of direct amination of β-ketoesters catalyzed by copper(II)-bisoxazoline(BOX)

The mechanism of the direct amination of β-keto esters catalyzed by copper(II)-bisoxazoline has been studied by means of density functional theory of B3LYP method. The computational results support the present mechanism, which involves (i) the generation of the enol from β-keto esters, which coordinates to copper(II)-bisoxazoline. The coordination step appears to be fast, exothermic, and irreversible. (ii) The formation of the σ(N-C) bond via a six-membered ring transition state after azo dicarboxylate coordination with the chiral catalyst. This step is chirality-control step. (iii) Intramolecular hydrogen migration generates a catalyst-product complex, which can finally yield product. The hydrogen shift is the rate-determining step, which affords the experimentally observed (R)-product. The stereochemical predictions have been rationalized in terms of steric repulsions, showing good agreement with experimental data. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Removal of nestling radio-transmitters by adult Sprague’s Pipit (Anthus spragueii)

Fledgling birds are notoriously difficult to find and capture because of their cryptic behavior. As a result, researchers usually affix transmitters to nestlings to study aspects of post-fledging ecology. However, parents may attempt to remove nestling transmitters, which could negatively impact nestlings. We attached radio-transmitters to 95 Sprague’s Pipit (Anthus spragueii) nestlings using a modified Rappole and Tipton leg harness. Within 1–2 days after transmitter attachment, we recorded six cases of parents removing transmitters from nestlings and depositing the transmitters outside the nest. At one of these nests, we videotaped parents pecking and pulling at nestlings that had transmitters and also dragging a nestling out of the nest by the transmitter. Of 12 video-monitored nests where we attached transmitters to nestlings, 33% had cases of parents attempting to remove transmitters by pecking and pulling at nestlings. Our observations highlight the need to closely monitor nestlings with transmitters so that researchers have the opportunity to reattach transmitters should parents remove them and to monitor the health of nestlings. Video-monitoring nests could also help to identify any unseen, negative impacts on nestlings due to transmitter attachment.     

Study of the inclusion of the (R)- and (S)-camphor enantiomers in α-cyclodextrin by X-ray crystallography and molecular dynamics

The inclusion of (R)- and (S)-camphor compounds in α-cyclodextrin has been studied by X-ray crystallography. The crystal structures of the complexes reveal that one guest molecule is accommodated inside the cavity formed by a head-to-head cyclodextrin dimer. In the crystal lattice, the dimers form layers which are successively shifted by half a dimer. In both (R)- and (S)-cases, the camphor molecule exhibits disorder and occupies three major sites with orientations that can be described as either ‘polar’ or ‘equatorial’. Molecular dynamics simulations performed for the observed complexes indicate that although the carbonyl oxygen of both (R)- and (S)-camphor switches between different hydrogen bonding partners, it maintains the observed mode of ‘polar’ or ‘equatorial’ alignment.     

Regulation of Induced Pluripotent Stem (iPS) Cell Induction by Wnt/β-Catenin Signaling

Wnt signaling has been implicated in promoting somatic cell reprogramming. However, its molecular mechanisms remain unknown. Here we report that Wnt/β-catenin enhances iPSCs induction at the early stage of reprogramming. The augmented reprogramming induced by β-catenin is not due to increased total cell population or activation of c-Myc. In addition, β-catenin interacts with reprogramming factors Klf4, Oct4, and Sox2, further enhancing expression of pluripotency circuitry genes. These studies reveal novel mechanisms underlying the regulation of reprogramming somatic cells to pluripotency by Wnt/β-catenin signaling.     

Inhibition of Cytidine Deaminase by Derivatives of 1-(β-D-Ribofuranosyl)-Dihydropyrimidin-2-One (Zebularine)

Abstract

The 2′-deoxy and ara derivatives of 1-β-(D-ribofuranosyl)-1,2-dihydropyrimidin-2-one (zebularine) were synthesized by improved routes and tested for their inhibitory properties against cytidine deaminase. It was shown that the K_i′s of both compounds were comparable to that of the parent zebularine in inhibition studies with purified enzyme. In contrast to zebularine, 2′-deoxy and ara zebularine showed only nominal cytotoxicity against MOLT-4 and L1210 cells in vitro. A model compound for the inhibition of deoxycytidylate deaminase, 2′-deoxyzebularine 5′-monophosphate (6), was also prepared.     

Relocation of Croton sonderianus (Euphorbiaceae) seeds by Pheidole fallax Mayr (Formicidae): a case of post-dispersal seed protection by ants?

Although seed dispersal by ants might reduce seed predation near the parent plants, predation on discarded seeds clustered on nest refuse piles may reduce any initial benefit provided by seed removal. Here we examine the fate of Croton sonderianus seeds that were discarded by Pheidole fallax Mayr ants on their nest refuses in caatinga vegetation of northeast Brazil. We collected all seeds discarded in refuse piles of 20 nests and within a radius of 50 cm from their borders, and examined them for evidence of predation. A total of 3,017 seeds were recorded either located in the P. fallax refuse piles (89.1%) or nest vicinity (10.9%). Predation was three fold higher in nest vicinity as compared to refuse piles. By removing seeds from beneath parent plants and relocating then to refuse piles, P. fallax is possibly providing double protection services for C. sonderianus seeds. Our findings represent the first evidence for predator-avoidance as benefit for plants resulting from ant seed-dispersal in the neotropics.     

Classification of α 1-antitrypsin (Pi) phenotypes by isoelectrofocusing

Summary Pi phenotypes have been determined by isoelectrofocusing in a sample of 538 healthy individuals from Southern Germany. Further subdivision of the common PiM phenotype is described. A procedure for the delineation of six common subtypes is presented. It is assumed that the six subtypes are determined by three alleles which are provisionally called Pi^Ma, Pi^Mb, and Pi^Mc. Their frequencies in this sample were 0.75, 0.06, and 0.15, respectively.Supported in part by INSERM, contract No. AT-FA-58     

Factor-free (“Non-enzymic”) and factor-dependent systems of translation of polyuridylic acid by Escherichia coli ribosomes

Systems of poly(U)-directed polyphenylalanino synthesis by Escherichia coli ribosomes in the absence of elongation factors and GTP (factor-free system) or in the presence of one of the elongation factors and GTP (EF-G² and EF-T_u-deperident systems) are described. It is shown that the use of oligouridylates of different length as templates in the factor-free system results in peptides, the degree of polymerization of which does not exceed the number of template codons, i.e. a conjugated translocation of the peptidyl-tRNA and the template takes place. Thus, the function of translocation as well as the specific binding of aminoacyl-tRNA and transpeptidation proved to be intrinsic to the ribosome itself. The study of kinetics of polyphenylalanine synthesis and dependence of the synthesis rate on the Mg²⁺ concentration in the factor-free, EF-T_u-dependent and EF-G-dependent translation systems has demonstrated that the elongation factors with GTP promote ribosomal mechanisms of aminoacyl-tRNA binding and translocation, respectively. It turned out that the factor-free translation system does not display miscoding. It is the promotion of translocation by EF-G with GTP that has been found to be responsible in full measure for miscoding, while EF-T_U with GTP does not contribute to this.     

Regulation of α(2B)-adrenergic receptor-mediated extracellular signal-regulated kinase 1/2 (ERK1/2) activation by ADP-ribosylation factor 1

A number of signaling molecules are involved in the activation of the mitogen-activated protein kinase (MAPK) pathway by G protein-coupled receptors. In this study, we have demonstrated that α(2B)-adrenergic receptor (α(2B)-AR) interacts with ADP-ribosylation factor 1 (ARF1), a small GTPase involved in vesicle-mediated trafficking, in an agonist activation-dependent manner and that the interaction is mediated through a unique double Trp motif in the third intracellular loop of the receptor. Interestingly, mutation of the double Trp motif and siRNA-mediated depletion of ARF1 attenuate α(2B)-AR-mediated activation of extracellular signal-regulated kinases 1/2 (ERK1/2) without altering receptor intracellular trafficking, whereas expression of the constitutively active mutant ARF1Q71L and ARNO, a GDP-GTP exchange factor of ARF1, markedly enhances the activation of Raf1, MEK1, and ERK1/2. These data strongly demonstrate that the small GTPase ARF1 modulates ERK1/2 activation by α(2B)-AR and provide the first evidence indicating a novel function for ARF1 in regulating the MAPK signaling pathway.     

Inhibition of β-N-acetylglucosaminidase by acetamide affects sperm motility and fertilization success of rainbow trout (Oncorhynchus mykiss) and Siberian sturgeon (Acipenser baerii)

β-N-Acetylglucosaminidase (β-NAGase) is an enzyme found in the sperm acrosome of numerous animal species including fish. Fish spermatozoa differ in their morphology including acrosome or acrosomeless aquasperm in chondrostean (e.g., sturgeon) and teleostean (e.g., rainbow trout). It has been shown that β-NAGase exists with high activity in both eggs and sperm of these species. The present study shows the potency of β-NAGase in fertilization. In rainbow trout, increase in sperm motility parameters (VAP and MOT) were observed in the presence of acetamide, an inhibitor for β-NAGase. In contrast, sperm motility parameters (VCL, VSL, VAP, MOT, and PRG) were reduced on the Siberian sturgeon in the presence of acetamide. The inhibition of the activity of β-NAGase in rainbow trout spermatozoa was led to a reduction in the number of fertilized eggs from 79% to 40%, whereas in sturgeon no change was observed in fertilization. Moreover, inhibition of β-NAGase in both spermatozoa and eggs of trout and sturgeon resulted in significant decrease in fertilization rate from 79% to 1% in rainbow trout and from 84% to 12% in Siberian sturgeon. Our research proves that β-NAGase can play a significant role in the fertilization process in teleosteans.