Antioxidative responses in females and males of the spider Xerolycosa nemoralis (Lycosidae) exposed to natural and anthropogenic stressors

The aim of this study was to assess the intensity of enzymatic antioxidative parameters [i.e., superoxide dismutase (SOD), catalase (CAT), and the glutathione peroxidases each selene dependent, GPOX or selene independent, including GSTPx, glutathione S-transferase, and GST] and non-enzymatic antioxidative parameters [i.e., glutathione total (GSH-t), the heat shock proteins of Hsp70, and metallothioneins (Mt)] in the midgut glands of female and male wolf spiders Xerolycosa nemoralis (Lycosidae) exposed to natural stressors (i.e., heat shock and starvation) and anthropogenic stressors (i.e., the organophosphorous pesticide dimethoate) under laboratory conditions. The spiders were collected from two differentially polluted sites both localized in southern Poland: Olkusz, which is heavily polluted with metals, and Pilica, the reference site. In response to the stressing factors, increases in Hsp70 levels, in the concentrations of total glutathione and in the activity levels of glutathione-dependent enzymes (GPOX, GSTPx, and GST) were found in the midgut glands of males. In the females, high levels of activity of CAT and SOD were revealed, as well as an increased percentage of Mt-positive cells. Preexposed females, in comparison to the individuals from the reference site, responded with increased SOD activity, irrespective of the stressing factor. In contrast, the changes in the antioxidative parameters in the midgut glands of male X. nemoralis seem to reflect a short-term reaction to the applied stressors and do not confirm the effects of long-term selection in a polluted environment.     

Soluble tumour necrosis factor-α receptor type 1 as a biomarker of response to phototherapy in patients with psoriasis

Abstract

The purpose of the study was to analyze the relationship between the serum concentration of soluble tumour necrosis factor-α type 1 (sTNF-R1), the severity of plaque-type psoriasis and therapeutic response. We compared sTNF-R1 in 25 patients treated with narrowband ultraviolet B (NB-UVB) radiation and 25 patients treated with systemic photochemotherapy (psoralen plus UVA – PUVA). The pretreatment Psoriasis Area and Severity Index (PASI) score and sTNF-R1 concentration were 16.32±5.26 and 1.99±0.40 ng ml^?1, respectively, in the group treated with NB-UVB, and 17.22±3.48 and 2.07±0.31 ng ml^?1, respectively, in the group treated with PUVA. The concentration of sTNF-R1 in healthy controls was 1.49±0.34 ng ml^?1 (p<0.05 compared with patients with psoriasis). The pretreatment PASI score correlated with sTNF-R1 in both treatment groups (r=0.46 and r=0.44, p<0.05). NB-UVB and PUVA gave similar therapeutic effects (the PASI score after 20 treatments was 4.42±1.67 in the NB-UVB-treated group and 5.55±2.10 in PUVA-treated patients); however, the sTNF-R1 concentration at the same time differed significantly: 1.52±0.37 ng ml^?1 and 1.98±0.39 ng ml^?1 (p<0.001), respectively. Moreover, the decline in sTNF-R1 in both treatment groups was significant only in patients in whom the duration of skin lesions was less than 3 months. The results suggest that the value of serum sTNF-R1 concentration as a marker of response to phototherapy may depend on duration of skin lesions and the treatment method.     

Temperature-induced changes of HtrA2(Omi) protease activity and structure

HtrA2(Omi), belonging to the high-temperature requirement A (HtrA) family of stress proteins, is involved in the maintenance of mitochondrial homeostasis and in the stimulation of apoptosis, as well as in cancer and neurodegenerative disorders. The protein comprises a serine protease domain and a postsynaptic density of 95 kDa, disk large, and zonula occludens 1 (PDZ) regulatory domain and functions both as a protease and a chaperone. Based on the crystal structure of the HtrA2 inactive trimer, it has been proposed that PDZ domains restrict substrate access to the protease domain and that during protease activation there is a significant conformational change at the PDZ–protease interface, which removes the inhibitory effect of PDZ from the active site. The crystal structure of the HtrA2 active form is not available yet. HtrA2 activity markedly increases with temperature. To understand the molecular basis of this increase in activity, we monitored the temperature-induced structural changes using a set of single-Trp HtrA2 mutants with Trps located at the PDZ–protease interface. The accessibility of each Trp to aqueous medium was assessed by fluorescence quenching, and these results, in combination with mean fluorescence lifetimes and wavelength emission maxima, indicate that upon an increase in temperature the HtrA2 structure relaxes, the PDZ–protease interface becomes more exposed to the solvent, and significant conformational changes involving both domains occur at and above 30 °C. This conclusion correlates well with temperature-dependent changes of HtrA2 proteolytic activity and the effect of amino acid substitutions (V226K and R432L) located at the domain interface, on HtrA2 activity. Our results experimentally support the model of HtrA2 activation and provide an insight into the mechanism of temperature-induced changes in HtrA2 structure.

Electronic supplementary material

The online version of this article (doi:10.1007/s12192-012-0355-1) contains supplementary material, which is available to authorized users.     

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.     

Kinetics of jack bean urease inhibition by 2,3-dichloro-1,4-naphthoquinone. Elucidation of the mechanism: redox cycling and sulfhydryl arylation

The inhibition of jack bean urease by 2,3-dichloro-1,4-naphthoquinone (DCNQ) was studied at ambient temperature in 20?mM phosphate buffer, pH 7.8. The process was investigated by incubation procedure in the absence of substrate. It was found that DCNQ acted as a time- and concentration-dependent inactivator of urease. The time course of the reaction displayed a biphasic mode. Each phase followed a pseudo-first-order kinetics, however the inactivation rate at the first phase was significantly faster than at the next one. The biphasity indicated the complex mechanism of DCNQ action on urease. Quinones action on proteins has been elucidated as at least two processes: direct arylation of essential protein thiols and/or indirect oxidation of essential thiols by reactive oxygen species (ROS) realising during quinone reduction to semiquinones. The next evidence of the studied mechanism was provided by the reactivation experiment that showed the participation of reversible and irreversible processes in the inactivation. The application of dithiothreitol (DTT) into DCNQ blocked-urease solution resulted in an effective enzyme activity regain which quickly returned to 70?±?10%. The irreversible inactivation of urease was attributed to DCNQ arylation of thiol residues in the protein. On the other hand, it was assumed that the reversible inactivation was a result of the action of ROS such as H₂O₂. Presence of H₂O₂ in the incubation system was proved by an experiment with the use of catalase. The enzyme by the elimination of H₂O₂ decreased DCNQ inactivating influence on urease. The comparison of participation of the fast and slow phase in the inactivation with the percentage of the process reversibility was assumed that the fast period was a result of the arylation mechanism while the slow phase was related to the oxidative influence of H₂O₂.     

The new insight into extracellular NAD+ degradation-the contribution of CD38 and CD73 in calcific aortic valve disease

Nicotinamide adenine dinucleotide (NAD⁺) is crucial for cell energy metabolism and many signalling processes. Recently, we proved the role of ecto-enzymes in controlling adenine nucleotide–dependent pathways during calcific aortic valve disease (CAVD). This study aimed to investigate extracellular hydrolysis of NAD⁺ and mononucleotide nicotinamide (NMN) in aortic valves and aorta fragments of CAVD patients and on the inner aortic surface of ecto-5′-nucleotidase knockout mice (CD73−/−). Human non-stenotic valves (n = 10) actively converted NAD⁺ and NMN via both CD73 and NAD⁺-glycohydrolase (CD38) according to our analysis with RP-HPLC and immunofluorescence. In stenotic valves (n = 50), due to reduced CD73 activity, NAD⁺ was degraded predominantly by CD38 and additionally by ALP and eNPP1. CAVD patients had significantly higher hydrolytic rates of NAD⁺ (0.81 ± 0.07 vs 0.56 ± 0.10) and NMN (1.12 ± 0.10 vs 0.71 ± 0.08 nmol/min/cm²) compared with controls. CD38 was also primarily engaged in human vascular NAD⁺ metabolism. Studies using specific ecto-enzyme inhibitors and CD73−/− mice confirmed that CD73 is not the only enzyme involved in NAD⁺ and NMN hydrolysis and that CD38 had a significant contribution to these pathways. Modifications of extracellular NAD⁺ and NMN metabolism in aortic valve cells may be particularly important in valve pathology and could be a potential therapeutic target.     

What do we know about winter active ground beetles (Coleoptera,Carabidae) in Central and Northern Europe?

This paper summarizes the current knowledge on winter active Carabidae in Central and Northern Europe. In total 73 winter active species are listed, based on literature and own observations. Ground beetles are among the three most numerous Coleoptera families active during the autumn to spring period. The winter community of Carabidae is composed both of larvae (mainly autumn breeding species) and adults, as well as of epigeic species and those inhabiting tree trunks. Supranivean fauna is characterized by lower species diversity than the subnivean fauna. The activity of ground beetles decreases in late autumn, is lowest during mid-winter and increases in early spring. Carabidae are noted as an important food source in the diet of insectivorous mammals. They are also predators, hunting small winter active invertebrates.