Evidence of a landlocked reproducing population of the marine pejerrey Odontesthes argentinensis (Actinopterygii; Atherinopsidae)

In South America, the order Atheriniformes includes the monophyletic genus Odontesthes with 20 species that inhabit freshwater, estuarine and coastal environments. Pejerrey Odontesthes argentinensis is widely distributed in coastal and estuarine areas of the Atlantic Ocean and is known to foray into estuaries of river systems, particularly in conditions of elevated salinity. However, to our knowledge, a landlocked self-sustaining population has never been recorded. In this study, we examined the pejerrey population of Salada de Pedro Luro Lake (south-east of Buenos Aires Province, Argentina) to clarify its taxonomic identity. An integrative taxonomic analysis based on traditional meristic, landmark-based morphometrics and genetic techniques suggests that the Salada de Pedro Luro pejerrey population represents a novel case of physiological and morphological adaptation of a marine pejerrey species to a landlocked environment and emphasises the environmental plasticity of this group of fishes.     

Characterization of the effects of a polyunsaturated fatty acid (PUFA) on mitochondrial bioenergetics of chronologically aged yeast

Increased membrane unsaturation has been associated with shorter longevity due to higher sensitivity to lipid peroxidation (LP) leading to enhanced mitochondrial dysfunction and ROS overproduction. However, the role of LP during aging has been put in doubt along with the participation of electron leak at the electron transport chain (ETC) in ROS generation in aged organisms. Thus, to test these hypothesis and gain further information about how minimizing LP preserves ETC function during aging, we studied the effects of α-linolenic acid (C18:3) on in situ mitochondrial ETC function, ROS production and viability of chronologically aged cells of S. cerevisiae, whose membranes are intrinsically resistant to LP due to the lack of PUFA. Increased sensitivity to LP was observed in cells cultured with C18:3 at 6 days of aging. This was associated with higher viability loss, dissipated membrane potential, impaired respiration and increased ROS generation, being these effects more evident at 28 days. However, at this point, lower sensitivity to LP was observed without changes in the membrane content of C18:3, suggesting the activation of a mechanism counteracting LP. The cells without C18:3 display better viability and mitochondrial functionality with lower ROS generation even at 28 days of aging and this was attributed to full preservation of complex III activity. These results indicate that the presence of PUFA in membranes enhances ETC dysfunction and electron leak and suggest that complex III is crucial to preserve membrane potential and to maintain a low rate of ROS production during aging.     

Toxin-Antitoxin Systems in the Mobile Genome of Acidithiobacillus ferrooxidans

Toxin-antitoxin (TA) systems are genetic modules composed of a pair of genes encoding a stable toxin and an unstable antitoxin that inhibits toxin activity. They are widespread among plasmids and chromosomes of bacteria and archaea. TA systems are known to be involved in the stabilization of plasmids but there is no consensus about the function of chromosomal TA systems. To shed light on the role of chromosomally encoded TA systems we analyzed the distribution and functionality of type II TA systems in the chromosome of two strains from Acidithiobacillus ferrooxidans (ATCC 23270 and 53993), a Gram-negative, acidophilic, environmental bacterium that participates in the bioleaching of minerals. As in other environmental microorganisms, A. ferrooxidans has a high content of TA systems (28-29) and in twenty of them the toxin is a putative ribonuclease. According to the genetic context, some of these systems are encoded near or within mobile genetic elements. Although most TA systems are shared by both strains, four of them, which are encoded in the active mobile element ICEAfe1, are exclusive to the type strain ATCC 23270. We demostrated that two TA systems from ICEAfe1 are functional in E. coli cells, since the toxins inhibit growth and the antitoxins counteract the effect of their cognate toxins. All the toxins from ICEAfe1, including a novel toxin, are RNases with different ion requirements. The data indicate that some of the chromosomally encoded TA systems are actually part of the A. ferrooxidans mobile genome and we propose that could be involved in the maintenance of these integrated mobile genetic elements.     

乌鲁木齐雅玛里克山土壤动物群落结构及其多样性研究

为了查明不同海拔高度对土壤动物群落多样性及其时空动态的影响,对乌鲁木齐雅玛里克山6种不同海拔高度样带土壤动物群落进行了调查分析,以探讨雅玛里克山土壤动物群落结构与不同海拔高度之间的关系.结果表明,共获得大、中小型土壤动物7 375只,隶属于6门16纲35目,其中真螨目(52.28%)和弹尾目(15.61%)为优势类群,共占总捕获量的67.89%,而寄螨目(8.37%)、三肠目(7.78%)、膜翅目(2.74%)、茅线目(1.53%)、双翅目幼虫(1.48%)、垫刃目(1.27%)、鞘翅目(1.11%)及半翅目(1.07%)等8类为常见类群,占总捕获量的25.35%,其余的25类为稀有类群,占总捕获量的6.76%.在6种不同海拔样带土壤动物个体数和类群数之间存在显著差异(P<0.05),个体数顺序为:样带A>样带B>样带C>样带E>样带D>样带F,而类群数顺序为:样带A>样带B>样带C>样带D>样带E>样带F.3个不同季节有明显的差异(P<0.01),其个体数依次为秋>春>夏.在6种不同高度样带和不同生境土壤动物群落多样性指标之间存在差异(P<0.05).组间聚类和排序结果表明,将6种不同海拔高度生境分为山底生境型、山中生境型及山顶生境型等三大类型.     

Gas chromatographic–mass spectrometric determination of serum mexiletine concentration after derivatization with perfluorooctanoyl chloride, a new derivative

Mexiletine is an antiarrhythmic agent used in the treatment of ventricular arrhythmia. The drug has a narrow therapeutic window which necessitates monitoring its serum concentrations. We describe a gas chromatographic–mass spectrometric analysis of mexiletine using selected ion monitoring. Mexiletine was extracted from alkaline serum with dichloromethane and then derivatized with perfluorooctanoyl chloride. The derivatization reaction was completed in 20 min at 80°C. We used N-propylamphetamine as the internal standard. The ions monitored were m/z 122, 454 and 575 for the derivatized mexiletine and m/z 91, 118, 440 and 452 for the derivatized internal standard. The within-run precision at a serum mexiletine concentration of 1 mg/l was 1.9% (mean=0.98, S.D.=0.019 mg/l, n=7) and the between-run precision was 2.5% (mean=0.99, S.D.=0.025 mg/l, n=7). The assay was linear for serum mexiletine concentrations of 0.2 to 4 mg/l. The detection limit was 0.1 mg/l. The average recoveries of mexiletine and the internal standard were 80% and 84%, respectively at a mexiletine concentration of 1 mg/l. There was no carry over problem in our assay. We observed a good correlation between mexiletine concentrations measured by a reference laboratory (GC) and by our new GC–MS assay.     

Anti-Ulcerogenic Effect of Methanolic Extracts from Enicosanthellum pulchrum (King) Heusden against Ethanol-Induced Acute Gastric Lesion in Animal Models

A natural source of medicine, Enicosanthellum pulchrum is a tropical plant which belongs to the family Annonaceae. In this study, methanol extract from the leaves and stems of this species was evaluated for its gastroprotective potential against mucosal lesions induced by ethanol in rats. Seven groups of rats were assigned, groups 1 and 2 were given Tween 20 (10% v/v) orally. Group 3 was administered omeprazole 20 mg/kg (10% Tween 20) whilst the remaining groups received the leaf and stem extracts at doses of 150 and 300 mg/kg, respectively. After an additional hour, the rats in groups 2–7 received ethanol (95% v/v; 8 mL/kg) orally while group 1 received Tween 20 (10% v/v) instead. Rats were sacrificed after 1 h and their stomachs subjected to further studies. Macroscopically and histologically, group 2 rats showed extremely severe disruption of the gastric mucosa compared to rats pre-treated with the E. pulchrum extracts based on the ulcer index, where remarkable protection was noticed. Meanwhile, a significant percentage of inhibition was shown with the stem extract at 62% (150 mg/kg) and 65% (300 mg/kg), whilst the percentage with the leaf extract at doses of 150 and 300 mg/kg was 63% and 75%, respectively. An increase in mucus content, nitric oxide, glutathione, prostaglandin E2, superoxide dismutase, protein and catalase, and a decrease in malondialdehyde level compared to group 2 were also obtained. Furthermore, immunohistochemical staining of groups 4–7 exhibited down-regulation of Bax and up-regulation of Hsp70 proteins. The methanol extract from the leaves and the stems showed notable gastroprotective potential against ethanol.     

Increase in the ability of human cancer cells to induce cytotoxic T lymphocytes by ultraviolet irradiation

The roles of ultraviolet-B (UV) radiation in the immunogenicity of human cancer cells have not been fully studied. We have investigated the effects of UV radiation on metastatic melanoma and renal cell carcinoma cells with regard to MHC antigen expression and the ability to induce cytotoxic T lymphocyte (CTL) activity in peripheral blood mononuclear cells (PBMC) or tumor-infiltrating lymphocytes (TIL) against untreated autologous tumor cells. UV radiation respectively decreased or increased MHC class I expression of freshly isolated tumor cells or cultured tumor cells, and also decreased MHC class I expression of starved cultured tumor cells. It increased the ability of both freshly isolated and cultured tumor cells to induce CTL activity from PBMC against untreated autologous tumor cells. UV-irradiated subclones that were more susceptible to CTL lysis were more potent for CTL induction from TIL than either an untreated parental clone or a UV-irradiated subclone that was resistant to CTL lysis. In summary, UV radiation increased the ability of tumor cells to induce CTL activity without a corresponding effect on MHC antigen expression.This work was supported in part by a grant CA47891 from the National Cancer Institute, USA, a grant-in-aid of the comprehensive 10-years strategy for cancer control from ministry of a Health and Welfare, Japan, and the Ishibashi Research Fund, Japan     

Remote opto‐acoustic probing of single‐cell adhesion on metallic surfaces

The reflection of picosecond ultrasonic pulses from a cell‐substrate interface is used to probe cell‐biomaterial adhesion with a subcell resolution. We culture monocytes on top of a thin biocompatible Ti metal film, supported by a transparent sapphire substrate. Low‐energy femtosecond pump laser pulses are focused at the bottom of the Ti film to a micron spot. The subsequent ultrafast thermal expansion launches a longitudinal acoustic pulse in Ti, with a broad spectrum extending up to 100 GHz. We measure the acoustic echoes reflected from the Ti‐cell interface through the transient optical reflectance changes. The time‐frequency analysis of the reflected acoustic pulses gives access to a map of the cell acoustic impedance Z_c and to a map of the film‐cell interfacial stiffness K simultaneously. Variations in Z_c across the cell are attributed to rigidity and density fluctuations within the cell, whereas variations in K are related to interfacial intermolecular forces and to the nano‐architecture of the transmembrane bonds. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation and Optimization of Fast-Disintegrating Tablet Containing Naratriptan Hydrochloride Using D-Optimal Mixture Design

Optimization of a lyophilized fast-disintegrating tablet (LFDT) formulation containing naratriptan hydrochloride, an antimigraine drug, was the foremost objective of the study, aiming in achieving fast headache pain relief. The Design-Expert® v10 software was used to generate formulations using D-optimal mixture design with four components: gelatin (X₁), hydrolyzed gelatin (X₂), glycine (X₃), and mannitol (X₄) of total solid material (TSM) w/w. The effect of the relative proportion of each component was determined on friability (Y₁), hardness (Y₂), and in vitro disintegration time (Y₃), which was then applied for formulation optimization. In addition, their effect on tablet porosity was determined via scanning electron microscopy (SEM). Drug-excipient interaction was evaluated using differential scanning calorimetry (DSC). A comparative dissolution study against the conventional tablets was studied. Accelerated stability study was carried out in (Al/Al) and (Al/PVC) blister packs. An in vivo pharmacokinetic study was carried out to compare the optimized formulation and the conventional tablets. The optimized formulation’s responses were 0.30%, 3.4 kg, and 6.12 s for Y₁, Y₂, and Y₃, respectively. No drug-excipient interaction was specified via DSC. The optimized formulation exhibited porous structure as determined via SEM. Dissolution study demonstrated complete dissolution within 1.5 min. Study indicated stability for 78 months in (Al/Al) blister packs. In vivo pharmacokinetic study demonstrated that C_max, AUC_last, and AUC_inf were significantly higher for the developed formulation. As well, the T_max was 1 h earlier than that of convenient tablet. An LFDT would achieve a faster onset of action for naratriptan compared to other formulations.