The glutathione S-transferase gene superfamily: an in silico approach to study the post translational regulation

The use of plants to reclaim contaminated soils and groundwater, known as phytoremediation, is a promising biotechnological strategy which has gained a lot of attention in the last few years. Plants have evolved sophisticated detoxification systems against the toxin chemicals: following the uptake, the compounds are activated so that certain functional groups can conjugate hydrophilic molecules, such as thiols. The resulting conjugates are recognized by the tonoplast transporters and sequestered into the vacuoles. The xenobiotic conjugation with glutathione is mediated by enzymes which belong to the superfamily of glutathione S-transferases (GSTs) catalyzing the nucleophylic attack of the sulphur of glutathione on the electrophilic groups of the cytotoxic substrates therefore playing a crucial role in their degradation. This study was designed to identify the putative correlation between structural and functional characteristics of plant GST classes belonging to different plant species. Consequently, the protein sequences of the expressed GSTs have been retrieved from UniGene, classified and then analyzed in order to assess the evolutionary trend and to predict secondary structure. Moreover, the fingerprint analysis was performed with SCAN Prosite in the attempt to correlate meaningful signature profile and biological information. The results evidenced that all the soluble GSTs have a tendency to assume the α-helix secondary structure followed by random coil and β-sheet. The fingerprint analysis revealed that specific signature profiles related mainly to protein phosphorylation are in the GST classes of all considered species thus suggesting that they might be subjected to reversible activation by phosphorylation-mediated regulation. This approach provides the knowledge of the relationship between presence of conserved signature profile and biological function in the view of future selection of GSTs which might be employed in either mutagenesis or genetic engineering studies.     

Immobilization of Oenococcus oeni in lentikats® to develop malolactic fermentation in wines

Entrapment of Oenococcus oeni into a polymeric matrix based on polyvinyl alcohol (PVA) (Lentikats®) was successfully used to get a better development of malolactic fermentation (MLF) in wine. The incubation of immobilized cells in a nutrient medium before starting the MLF, did not improve the degradation of malic acid. In only one day, 100% of conversion of malic acid was achieved using a high concentration of immobilized cells (0.35 g gel/ml of wine with a cell‐loading of 0.25 mg cells/mg of gel). While a low concentration of 0.21 g gel/ml of wine (cell‐loading of 0.25 mg cells/mg of gel) needed 3 days to get a reduction of 40%. The entrapped cells could be reused through six cycles (runs of 3 days), retaining 75% of efficacy for the conversion of malic acid into lactic acid. The immobilized cells in PVA hydrogels gave better performance than free cells because of the increase of the alcohol toleration. Consequently, the inhibitory effect of ethanol for developing MLF could be reduced using immobilized cells into PVA hydrogels. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013     

Growth Monitoring: A Survey of Current Practices of Primary Care Paediatricians in Europe

Objective

We aimed to study current practices in growth monitoring by European primary care paediatricians and to explore their perceived needs in this field.

Methods

We developed a cross-sectional, anonymous on-line survey and contacted primary care paediatricians listed in national directories in the 18 European countries with a confederation of primary care paediatricians. Paediatricians participated in the survey between April and September 2011.

Results

Of the 1,198 paediatricians from 11 European countries (response rate 13%) who participated, 29% used the 2006 World Health Organization Multicentre Growth Reference Study growth charts, 69% used national growth charts; 61% used software to draw growth charts and 79% did not use a formal algorithm to detect abnormal growth on growth charts. Among the 21% of paediatricians who used algorithms, many used non-algorithmic simple thresholds for height and weight and none used the algorithms published in the international literature. In all, 69% of paediatricians declared that a validated algorithm to monitor growth would be useful in daily practice. We found important between-country variations.

Conclusion

The varied growth-monitoring practices declared by primary care paediatricians reveals the need for standardization and evidence-based algorithms to define abnormal growth and the development of software that would use such algorithms.     

Microparticle Shedding from Neural Progenitor Cells and Vascular Compartment Cells Is Increased in Ischemic Stroke

Purpose

Ischemic stroke has shown to induce platelet and endothelial microparticle shedding, but whether stroke induces microparticle shedding from additional blood and vascular compartment cells is unclear. Neural precursor cells have been shown to replace dying neurons at sites of brain injury; however, if neural precursor cell activation is associated to microparticle shedding, and whether this activation is maintained at long term and associates to stroke type and severity remains unknown. We analyzed neural precursor cells and blood and vascular compartment cells microparticle shedding after an acute ischemic stroke.

Methods

Forty-four patients were included in the study within the first 48h after the onset of stroke. The cerebral lesion size was evaluated at 3–7 days of the stroke. Circulating microparticles from neural precursor cells and blood and vascular compartment cells (platelets, endothelial cells, erythrocytes, leukocytes, lymphocytes, monocytes and smooth muscle cells) were analyzed by flow cytometry at the onset of stroke and at 7 and 90 days. Forty-four age-matched high cardiovascular risk subjects without documented vascular disease were used as controls.

Results

Compared to high cardiovascular risk controls, patients showed higher number of neural precursor cell- and all blood and vascular compartment cell-derived microparticles at the onset of stroke, and after 7 and 90 days. At 90 days, neural precursor cell-derived microparticles decreased and smooth muscle cell-derived microparticles increased compared to levels at the onset of stroke, but only in those patients with the highest stroke-induced cerebral lesions.

Conclusions

Stroke increases blood and vascular compartment cell and neural precursor cell microparticle shedding, an effect that is chronically maintained up to 90 days after the ischemic event. These results show that stroke induces a generalized blood and vascular cell activation and the initiation of neuronal cell repair process after stroke. Larger cerebral lesions associate with deeper vessel injury affecting vascular smooth muscle cells.     

Assessing the impact of extreme adverse weather on the biological traits of a European storm petrel colony

Climate change affects the climatic disturbance patterns and regimes and is altering the frequency and intensity of subtropical cyclones. These events can affect population dynamics of seabirds (e.g., survival, reproduction). In this work we tested the effect of adverse weather on a colony of European storm petrels (Hydrobates pelagicus) located in a small islet (Aketx) in northern Spain. Over a long-term monitoring period (1993–2014) we ringed 3728 petrels. From 2003 onwards we also monitored breeding success, the percentage of immature individuals and moult scores. We used Cormack-Jolly-Seber models and Underhill and Zucchini models to analyze the effects of climatic conditions on a number of biological traits (survival, breeding parameters, moulting patterns). Our analyses revealed a constant value of adult survival over the 26-year monitoring period. Recapture probability, however, tended to be positively influenced by NAO conditions in spring, and negatively influenced by NAO conditions in winter (although this would only affect to a fraction of first-captured birds). Moreover, the impact of adverse weather, especially in 2011 and 2014, resulted in an increasing proportion of yearlings in the breeding population, a lower breeding success and a delayed onset of moult. These effects were similar to those observed during the Prestige oil spill catastrophe.     

Putative spermine synthases from Thalassiosira pseudonana and Arabidopsis thaliana synthesize thermospermine rather than spermine

Polyamines are involved in many fundamental cellular processes. Common polyamines are putrescine, spermidine and spermine. Spermine is synthesized by transfer of an aminopropyl residue derived from decarboxylated S-adenosylmethionine to spermidine. Thermospermine is an isomer of spermine and assumed to be synthesized by an analogous mechanism. However, none of the recently described spermine synthases was investigated for their possible activity as thermospermine synthases. In this work, putative spermine synthases from the diatom Thalassiosira pseudonana and from Arabidopsis thaliana could be identified as thermospermine synthases. These findings may explain the previous result that two putative spermine synthase genes in Arabidopsis produce completely different phenotypes in knock-out experiments. Likely, part of putative spermine synthases identifiable by sequence comparisons represents in fact thermospermine synthases.     

Alterations in linker flexibility suppress DNA topoisomerase I mutant-induced cell lethality

Eukaryotic DNA topoisomerase I (Top1p) catalyzes changes in DNA topology via the formation of a covalent enzyme-DNA intermediate, which is reversibly stabilized by the anticancer agent camptothecin (CPT). Crystallographic studies of the 70-kDa C terminus of human Top1p bound to duplex DNA describe a monomeric protein clamp circumscribing the DNA helix. The structures, which lack the N-terminal domain, comprise the conserved clamp, an extended linker domain, and the conserved C-terminal active site Tyr domain. CPT bound to the covalent Top1p-DNA complex limits linker flexibility, allowing structural determination of this domain. We previously reported that mutation of Ala(653) to Pro in the linker increases the rate of enzyme-catalyzed DNA religation, thereby rendering Top1A653Pp resistant to CPT (Fiorani, P., Bruselles, A., Falconi, M., Chillemi, G., Desideri, A., and Benedetti P. (2003) J. Biol. Chem. 278, 43268-43275). Molecular dynamics studies suggested mutation-induced increases in linker flexibility alter Top1p catalyzed DNA religation. To address the functional consequences of linker flexibility on enzyme catalysis and drug sensitivity, we investigated the interactions of the A653P linker mutation with a self-poisoning T718A mutation within the active site of Top1p. The A653P mutation suppressed the lethal phenotype of Top1T718Ap in yeast, yet did not restore enzyme sensitivity to CPT. However, the specific activity of the double mutant was decreased in vivo and in vitro, consistent with a decrease in DNA binding. These findings support a model where changes in the flexibility or orientation of the linker alter the geometry of the active site and thereby the kinetics of DNA cleavage/religation catalyzed by Top1p.     

Optimal time-profiles of public health intervention to shape voluntary vaccination for childhood diseases

Journal of Mathematical Biology - In order to seek the optimal time-profiles of public health systems (PHS) Intervention to favor vaccine propensity, we apply optimal control (OC) to a SIR model...     

Maintenance of CDC42 GDP-bound state by Rho-GDI inhibits MAP kinase activation by the exchange factor Ras-GRF. evidence for Ras-GRF function being inhibited by Cdc42-GDP but unaffected by CDC42-GTP

The function of the Ras guanine nucleotide exchange factor Ras-GRF/cdc25(Mn) is subject to tight regulatory processes. We have recently shown that the activation of the Ras/MAPK pathway by Ras-GRF is controlled by the Rho family GTPase Cdc42 through still unknown mechanisms. Here, we report that retaining Cdc42 in its GDP-bound state by overexpressing Rho-GDI inhibits Ras-GRF-mediated MAPK activation. Conversely, Ras-GRF basal and LPA- or ionomycin-stimulated activities were unaffected by a constitutively active GTP-bound Cdc42. Moreover, the Cdc42 downstream effectors MLK3, ACK1, PAK1, and WASP had no detectable influence on Ras-GRF-mediated MAPK activation. In contrast, promoting GDP release from Cdc42 with the Rho family GEF Dbl or with ionomycin suppressed the restraint exerted by Cdc42 on Ras-GRF activity. We conclude that Cdc42-GDP inhibits Ras-GRF-induced MAPK activation, but neither Cdc42-GTP nor the Cdc42 downstream effectors affect Ras-GRF performance. Interestingly, the loss of the GDP-bound state by Cdc42 abolishes its inhibitory effects on Ras-GRF function. These results suggest that the Cdc42 mechanism of action may not be solely restricted to activation of downstream signaling cascades when GTP-loaded. Furthermore, the GDP-bound form may be acting as an inhibitory molecule down-modulating parallel signaling routes such as the Ras/MAPK pathway.