Small Ubiquitin-like Modifier (SUMO) Isoforms and Conjugation-independent Function in DNA Double-strand Break Repair Pathways

Small ubiquitin-like modifier (SUMO) proteins act in DNA double-strand break (DSB) repair, but the pathway specificity of the three major isoforms has not been defined. In experiments in which we depleted the endogenous SUMO protein by RNAi, we found that SUMO1 functioned in all subpathways of either homologous recombination (HR) or non-homologous end joining (NHEJ), whereas SUMO2/3 was required for the major NHEJ pathway, called conservative NHEJ, but dispensable in other DSB repair pathways. To our surprise, we found that depletion of UBC9, the unique SUMO E2 enzyme, had no effect in HR or alternative NHEJ (Alt-NHEJ) but was required for conservative NHEJ. Consistent with this result, both non-conjugatable mutant and wild-type SUMO1 proteins functioned similarly in HR and Alt-NHEJ. These results detail the functional roles of specific SUMO isoforms in DSB repair in mammalian cells and reveal that SUMO1 functions in HR or Alt-NHEJ as a free protein and not as a protein conjugate.     

Dose-dependent modulation of systemic lipid peroxidation and activity of anti-oxidant enzymes by vitamin E in the rat

The objective of this work was to examine the time-dependent pro-oxidant versus antioxidant effect of various doses of vitamin E used commonly in experimental studies. Erythrocyte activity of superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) and plasma lipid peroxidation levels were investigated following biweekly intramuscular administration of 100, 300 and 600 mg/kg of vitamin E at a baseline time point, and additionally at 2, 4 and 6 weeks after initiating treatment. Vitamin E had an antioxidant effect when administered at low doses over short time periods, and increased the activity of antioxidant enzymes. At higher doses and over longer time periods, it increased the level of lipid peroxidation, and attenuated the activity of antioxidant enzymes. These results suggest that time-dependent variations in vitamin E effects should be considered in design and interpretation of experimental antioxidant studies, as well as during clinical trials.     

Inhibition of the mevalonate pathway enhances carvacrol biosynthesis and DXR gene expression in shoot cultures of Satureja khuzistanica Jamzad

Carvacrol is a major component of Satureja khuzistanica Jamzad (≤90%) that has significant antimicrobial and antioxidant properties. Considering the specific capabilities of S. khuzistanica to produce highly pure carvacrol, this plant is an important potential source of carvacrol that could address the abundant consumption and increasing demand for this monoterpene in current world markets. This research was performed to better understand the process of biosynthesis and accumulation of carvacrol in S. khuzistanica. Tests were performed on shoot cultures of S. khuzistanica in Linsmaier-Skoog (LS) medium treated with different concentrations of fosmidomycin (an inhibitor of the non-mevalonate pathway) and mevinolin (an inhibitor of the mevalonate pathway) for 21 days at the following concentrations: 0, 10, 25, 50, 75 and 100 μM. The present study demonstrated that the MEP pathway is the major pathway that provides IPP for the biosynthesis of carvacrol, and the expression and activity levels of the DXR enzyme have a critical effect on carvacrol biosynthesis. Surprisingly, Mevinolin at concentrations of 75 and 100 μM increased the carvacrol content and the DXR activity and gene expression in S. khuzistanica plantlets.     

Development of a New Pollution Index for Heavy Metals in Sediments

This study aims to investigate the pollution rate of heavy metals on the western seaboard of Bandarabbas in southeast Iran using a new pollution index. The bulk of the analysis was conducted on sediments, followed by selection of a few samples to perform experiments on chemical partitioning studies as well as biological accessibility. On this basis, the proportions of natural and anthropogenic elements were calculated. Finally, with regard to chemical separation results, the pollution rate was calculated based on Muller's geo-chemical index, enrichment factor, pollution index, and a new "Risk" index. Chemical separation showed the anthropogenic origin of elements are as follows: Ni(27.5%) > Zn(6.5%) > Pb(2%) > Al (0.2%). The newly developed pollution index is indicative of "low environmental pollution "for Ni.     

Crystal structure of SCO6571 from Streptomyces coelicolor A3(2)

SCO6571 protein from Streptomyces coelicolor A3(2) was overexpressed and purified using Rhodococcus erythropolis as an expressing host. Crystals of selenomethionine-substituted SCO6571 have been obtained by vapor diffusion method. SCO6571 crystals diffract to 2.3 A and were found to belong to the orthorhombic space group P2(1)2(1)2(1) with unit cell parameters a = 84.5, b = 171.6, c = 184.8 A. Six molecules in the asymmetric unit give a crystal volume per protein mass (V(M)) of 2.97 A (3) Da(-1) and solvent content of 58.6 %. The structure was solved by the single wavelength anomalous diffraction (SAD) method. SCO6571 is a TIM-barrel fold protein that assembles into a hexameric molecule with D(3) symmetry.     

Tebuconazole and trifloxystrobin regulate the physiology,antioxidant defense and methylglyoxal detoxification systems in conferring salt stress tolerance in Triticum aestivum L.

Physiology and Molecular Biology of Plants - Fungicides are widely used for controlling fungi in crop plants. However, their roles in conferring abiotic stress tolerance are still elusive. In this...     

Biochemical characterisation of digestive proteases and carbohydrases of the pistachio fruit hull borer,Arimania komaroffi Ragonot (Lepidoptera: Pyralidae)

Pistachio fruit hull borer, Arimania komaroffi Ragonot (Lep.: Pyralidae), is one the most important pests of pistachio in Iran. The larvae spin web as well as bore into young fruits, and the infested fruits fall off the trees. The second-generation adult moths appear in August and September, and their offspring feed on the fruit hull. Results indicated the presence of α-amylase, α-glucosidase, β-glucosidase, α-galactosidase, β-galactosidase and some proteases in the digestive tract of the pest. Highest activities of α-amylase, α-glucosidase, β-glucosidase, α-galactosidase and β-galactosidase were at pH 10, 7, 7, 6 and pH 6, respectively. Highest activities of trypsin, chymotrypsin and elastase of larval midgut were at pH 11. Zymogram analysis of α-amylase, α-glucosidase, β-glucosidase, tryptic, chymotryptic and elastase using native-PAGE revealed 1, 1, 2, 3, 3 and 2 bands of activity respectively, in A. komaroffi. One band was disappeared in the presence of the inhibitor TLCK, but no further inhibition by the inhibitors TPCK was observed. The results can be of help for designing new strategies for controlling the pistachio fruit hull borer based on natural proteases and carbohydrase inhibitors.     

Surface EMG force modeling with joint angle based calibration

In this paper, a calibration method to compensate for changes in SEMG amplitude with joint angle is introduced. Calibration factors were derived from constant amplitude surface electromyogram (SEMG) recordings from the biceps brachii (during elbow flexion) and the triceps brachii (during elbow extension) across seven elbow joint angles. SEMG data were then recorded from the elbow flexors (biceps brachii and brachioradialis) and extensors (triceps brachii) during isometric, constant force flexion and extension contractions at the same joint angles. The resulting force at the wrist was measured. The fast orthogonal search method was used to find a mapping between the system inputs – estimated SEMG amplitudes and joint angle – and the system output – measured force, for both calibrated and non-calibrated SEMG data. Models developed with calibrated data yielded a statistically significant improvement in force estimation compared to models developed with non-calibrated data, suggesting that the calibration method can compensate for changes in the SEMG–force relationship with changing joint angle. It was also found that the number of non-linear, joint angle-dependent terms used in the SEMG–force model was reduced with calibration. Additionally, initial inter-session analysis performed for four subjects suggests that calibration values can be used for subsequent recording sessions, and different output force levels.