Role of a conserved aspartic acid in nucleotide binding domain 1 (NBD1) of Hsp100 chaperones in their activities

Besides its beneficial role in thermotolerance, the chaperone protein Hsp104 is involved in the inheritance of yeast Saccharomyces cerevisiae prions. Guanidine hydrochloride was previously shown to interfere with Hsp104 chaperone activity in vivo, thus impairing thermotolerance and resulting in prion curing. It was also reported that guanidine inhibits Hsp104 ATPase and disaggregation activity. We show that in vitro guanidine significantly inhibits the disaggregation activity of ClpB, the bacterial orthologue of Hsp104. However, guanidine exerts opposite effects on the ATPase activities of Hsp104 and ClpB. While the ATPase activity of Hsp104 is inhibited, the analogous ClpB activity is stimulated several-fold. Mutation of the universally conserved aspartic acid residue in position 184 to serine (D184S) in HSP104 and the analogous mutation in clpB (D178S) resulted in chaperones with lower disaggregating and ATPase activities. The activities of such changed chaperones are not influenced by guanidine, which suggests the role of this residue in the interaction with guanidine.     

Enhancement of neutral lipid productivity in the microalga Isochrysis affinis Galbana (T-Iso) by a mutation-selection procedure

Microalgae offer a high potential for energetic lipid storage as well as high growth rates. They are therefore considered promising candidates for biofuel production, with the selection of high lipid‐producing strains a major objective in projects on the development of this technology. We developed a mutation‐selection method aimed at increasing microalgae neutral lipid productivity. A two step method, based on UVc irradiation followed by flow cytometry selection, was applied to a set of strains that had an initial high lipid content and improvement was assessed by means of Nile‐red fluorescence measurements. The method was first tested on Isochrysis affinis galbana (T‐Iso). Following a first round of mutation‐selection, the total fatty acid content had not increased significantly, being for the wild type (WT) and for the selected population (S1M1). Conversely, fatty acid distribution among the lipid classes was affected by the process, resulting in a 20% increase for the fatty acids in the neutral lipids and a 40% decrease in the phospholipids. After a second mutation‐selection step (S2M2), the total fatty acid content reached with a fatty acid distribution similar to the S1M1 population. Growth rate remained unaffected by the process, resulting in a 80% increase for neutral lipid productivity. Biotechnol. Bioeng. 2012; 109: 2737–2745. © 2012 Wiley Periodicals, Inc.     

Counteraction of early circulatory derangement by administration of low dose steroid treatment at the onset of established endotoxemic shock is not directly mediated by TNF-α and IL-6

BackgroundOnce a septic condition is progressing, administration of steroids in the pro-inflammatory phase of septic shock ought to yield maximal effect on the subsequent, devastating inflammatory response. Recently, a retrospective study showed that early initiation of corticosteroid therapy improved survival in septic shock. We aimed to prospectively evaluate effects of early administrated hydrocortisone therapy on physiologic variables in a porcine model of septic shock.ExperimentEight anesthetized pigs were given a continuous infusion of endotoxin during this 6 h prospective, randomized, parallel-grouped placebo-controlled experimental study. At the onset of endotoxemic shock, defined as the moment when the mean pulmonary arterial pressure reached the double baseline value, the pigs were either given a single intravenous dose of hydrocortisone (5 mg kg^?1) or the corresponding volume of saline.ResultsMean arterial pressure and systemic vascular resistance index were significantly higher (both p < 0.05), and heart rate was significantly lower (p < 0.05), in the endotoxin + hydrocortisone group as compared to the endotoxin + saline group. Body temperature and blood hemoglobin levels increased significantly in the endotoxin + saline group (both p < 0.05). Urinary hydrocortisone increased significantly in both groups (p < 0.05). There were no significant differences in the plasma levels of TNF-alpha, IL-6 or nitrite/nitrate between the groups.ConclusionEarly treatment with hydrocortisone ameliorates some endotoxin mediated circulatory derangements, fever response and microvascular outflow. Our results suggest that these effects are not directly mediated by the pro-inflammatory cytokines TNF-alpha or IL-6, nor by NO.     

Variation in ribosomal and mitochondrial DNA sequences demonstrates the existence of intraspecific groups in Paramecium multimicronucleatum (Ciliophora, Oligohymenophorea)

This is the first phylogenetic study of the intraspecific variability within Paramecium multimicronucleatum with the application of two-loci analysis (ITS1-5.8S-ITS2-5'LSU rDNA and COI mtDNA) carried out on numerous strains originated from different continents. The species has been shown to have a complex structure of several sibling species within taxonomic species. Our analysis revealed the existence of 10 haplotypes for the rDNA fragment and 15 haplotypes for the COI fragment in the studied material. The mean distance for all of the studied P. multimicronucleatum sequence pairs was p=0.025/0.082 (rDNA/COI). Despite the greater variation of the COI fragment, the COI-derived tree topology is similar to the tree topology constructed on the basis of the rDNA fragment. P. multimicronucleatum strains are divided into three main clades. The tree based on COI fragment analysis presents a greater resolution of the studied P. multimicronucleatum strains. Our results indicate that the strains of P. multimicronucleatum that appear in different clades on the trees could belong to different syngens.     

Between Metabolite Relationships: an essential aspect of metabolic change

Not only the levels of individual metabolites, but also the relations between the levels of different metabolites may indicate (experimentally induced) changes in a biological system. Component analysis methods in current 'standard' use for metabolomics, such as Principal Component Analysis (PCA), do not focus on changes in these relations. We therefore propose the concept of 'Between Metabolite Relationships' (BMRs): common changes in the covariance (or correlation) between all metabolites in an organism. Such structural changes may indicate metabolic change brought about by experimental manipulation but which are lost with standard data analysis methods. These BMRs can be analysed by the INdividual Differences SCALing (INDSCAL) method. First the BMR quantification is described and subsequently the INDSCAL method. Finally, two studies illustrate the power and the applicability of BMRs in metabolomics. The first study is about the induced plant response of cabbage to herbivory, of which BMRs are a considerable part. In the second study-a human nutritional intervention study of green tea extract-standard data analysis tools did not reveal any metabolic change, although the BMRs were considerably affected. The presented results show that BMRs can be easily implemented in a wide variety of metabolomic studies. They provide a new source of information to describe biological systems in a way that fits flawlessly into the next generation of systems biology questions, dealing with personalized responses. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-011-0316-1) contains supplementary material, which is available to authorized users.     

Consequences of one-electron oxidation and one-electron reduction for 4-aminopyrimidine—DFT studies

The consequences of one-electron oxidation and one-electron reduction were studied for 4-aminopyrimidine (4APM), which displays prototropic tautomerism. Since experimental techniques are incapable of detecting less than 0.1% of minor tautomers, quantum-chemical calculations [DFT(B3LYP)/6-311+G(d,p)] were carried out for all possible tautomers of neutral 4AMP and its redox forms, 4APM (+ ?) and 4APM (- ?). Four tautomers were considered: one amine and three imine tautomers (two NH and one CH form). Geometric isomerism of the exo?=?NH group was also taken into account. One-electron oxidation (4APM - e → 4APM (+??)) has no significant effect on the tautomeric preferences; it influences solely the composition of the tautomeric mixture. The amine tautomer is favored for both 4APM (+??) and 4APM. An interesting change in the tautomeric preference occurs for 4APM (- ?). One-electron reduction (4APM?+?e → 4APM (- ?)) favors the C5 atom for the labile proton. The preference of the imine CH tautomer in the tautomeric mixture of 4APM (- ?) may partially explain the origin of CH tautomers in nucleobases.