Temperature dependence of superoxide dismutase activity in plankton

The effect of temperature (from 1 to 37 °C) on in vitro effective superoxide dismutase (SOD) activity of several organisms was investigated and compared. Antarctic plankton, cultures of the alga Nannochloropsis sp., and the cyanobacterium Synechococcus strain WH 7803, and pure bovine erythrocyte SOD was studied. It was found that in all cases SOD activity increased with decreasing temperature within the temperature range assayed, in the Polar as well as the temperate plankton cells. This behavior of SOD is counterintuitive in terms of our experience when looking at enzyme activity or any other chemical reaction. We suggest a theoretical explanation for this apparently odd behavior. The advantage of such behavior is that the same amount of antioxidant will act better under low temperatures when reactive oxygen species (ROS) increase. Moreover, this protective process would act in vivo at a faster pace than the ex novo enzyme synthesis.     

Glutathionylation of the p50 subunit of NF-kappaB: a mechanism for redox-induced inhibition of DNA binding.

The cellular redox status can modify the function of NF-kappaB, whose DNA-binding activity can be inhibited by oxidative, nitrosative, and nonphysiological agents such as diamide, iodoacetamide, or N-ethylmaleimide. This inhibitory effect has been proposed to be mediated by the oxidation of a conserved cysteine in its DNA-binding domain (Cys62) through unknown biochemical mechanisms. The aim of this work was to identify new oxidative modifications in Cys62 involved in the redox regulation of the NF-kappaB subunit p50. To address this problem, we exposed p50, both the native form (p50WT) and its corresponding mutant in Cys62 (C62S), to changes in the redox pair glutathione/glutathione disulfide (GSH/GSSG) ratio ranging from 100 to 0.1, which may correspond to intracellular (patho)physiological states. A ratio between 1 and 0.1 resulted in a 40-70% inhibition of the DNA binding of p50WT, having no effect on the C62S mutant. Mass spectrometry studies, molecular modeling, and incorporation of (3)H-glutathione assays were consistent with an S-glutathionylation of p50WT in Cys62. Maximal incorporation of (3)H-glutathione to the p50WT and C62S was of 0.4 and 0.1 mol of (3)H-GSH/mol of protein, respectively. Because this covalent glutathione incorporation did not show a perfect correlation with the observed inhibition in the DNA-binding activity of p50WT, we searched for other modifications contributing to the maximal inhibition. MALDI-TOF and nanospray-QIT studies revealed the formation of sulfenic acid as an alternative or concomitant oxidative modification of p50. In summary, these data are consistent with new oxidative modifications in p50 that could be involved in redox regulatory mechanisms for NF-kappaB. These postranslational modifications could represent a molecular basis for the coupling of pro-oxidative stimuli to gene expression.     

Rhesus macaques build new social connections after a natural disaster

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Studies on Disaccharide Nucleoside Synthesis. Mechanism of the Formation of Trisaccharide Purine Nucleosides

Abstract

The unexpected formation of trisaccharide nucleosides during synthesis of purine 5′-O-β-D-ribofuranosylnucleosides in the presence of Lewis acids was observed.     

Indoor Tracking to Understand Physical Activity and Sedentary Behaviour: Exploratory Study in UK Office Buildings

Little is known of the patterns of physical activity, standing and sitting by office workers. However, insight into these behaviours is of growing interest, notably in regard to public health priorities to reduce non-communicable disease risk factors associated with high levels of sitting time and low levels of physical activity. With the advent and increasing availability of indoor tracking systems it is now becoming possible to build detailed pictures of the usage of indoor spaces. This paper reports initial results of indoor tracking used in conjunction with the ActivPAL activity monitoring device. In this paper we give an overview of the usage of the tracking system and its installation and illustrate some of the resultant data. We also provide preliminary results that investigate the relationship between location, light physical activity and sitting in a small sample of office workers (n=33) from two separate office environments in order to demonstrate the relevance and explanatory power of the technique.