Assembly and disassembly of brain tubulin is affected by high ammonia levels

Rats were fed a diet containing ammonium for up to 6 months. High ammonia levels were attained in brain. The amount of polymerized tubulin in microtubules increased, while the amount of free tubulin remained unchanged. Polymerization of tubulin from brain of ammonium fed rats (30 min, 37°C) was approximately 60% of control. Depolymerization of the microtubules was also affected and took approximately 3 times longer than in controls. These results indicate that both assembly and disassembly of tubulin in brain are impaired by high ammonia levels. Interestingly, the amount of microtubule-associated proteins was not affected.     

Thermodynamics of glutathione binding to the tyrosine 7 to phenylalanine mutant of glutathione S-transferase from Schistosoma japonicum

The binding of glutathione (GSH) to the tyrosine 7 to phenylalanine mutant of Schistosoma japonicum glutathione S-transferase (SjGST-Y7F) has been studied by isothermal titration calorimetry (ITC). At pH 6.5 and 25 °C this mutant shows a higher affinity for glutathione than wild type enzyme despite an almost complete loss of activity in the presence of 1-chloro-2,4-dinitrobenzene (CDNB) as second substrate. The enthalpy change upon binding of GSH is more negative for the mutant than for the wild type GST (SjGST). Changes in accessible solvent areas (ASA) have been calculated based on enthalpy and heat capacity changes. ASA values indicated the burial of apolar surfaces of protein and ligand upon binding. A more negative ΔC_p value has been obtained for the mutant enzyme, suggesting a more hydrophobic interaction, as may be expected from the change of a tyrosine residue to phenylalanine.     

National mass drug administration costs for lymphatic filariasis elimination

Background

Because lymphatic filariasis (LF) elimination efforts are hampered by a dearth of economic information about the cost of mass drug administration (MDA) programs (using either albendazole with diethylcarbamazine [DEC] or albendazole with ivermectin), a multicenter study was undertaken to determine the costs of MDA programs to interrupt transmission of infection with LF. Such results are particularly important because LF programs have the necessary diagnostic and treatment tools to eliminate the disease as a public health problem globally, and already by 2006, the Global Programme to Eliminate LF had initiated treatment programs covering over 400 million of the 1.3 billion people at risk.

Methodology/Principal Findings

To obtain annual costs to carry out the MDA strategy, researchers from seven countries developed and followed a common cost analysis protocol designed to estimate 1) the total annual cost of the LF program, 2) the average cost per person treated, and 3) the relative contributions of the endemic countries and the external partners. Costs per person treated ranged from $0.06 to $2.23. Principal reasons for the variation were 1) the age (newness) of the MDA program, 2) the use of volunteers, and 3) the size of the population treated. Substantial contributions by governments were documented – generally 60%–90% of program operation costs, excluding costs of donated medications.

Conclusions/Significance

MDA for LF elimination is comparatively inexpensive in relation to most other public health programs. Governments and communities make the predominant financial contributions to actual MDA implementation, not counting the cost of the drugs themselves. The results highlight the impact of the use of volunteers on program costs and provide specific cost data for 7 different countries that can be used as a basis both for modifying current programs and for developing new ones.     

Molecular organization in bacterial cell membranes III. Components of a “soluble” fraction obtained by n-butanol extraction of Streptomyces albus membranes

We have isolated a “soluble” fraction of Streptomyces albus G membranes or membranes previously solubilised by sodium dodecylsulphate, using n-butanol extraction. Polyacrylamide gel electrophoresis in sodium dodecylsulphate of the whole membrane showed a complex protein pattern (about 20–25 bands) with two predominant groups. The “soluble” fraction represented about 25% of the membrane protein and contained part of the major polypeptides. The yield of protein in “soluble” form decreased when membranes were suspended in water and di not significantly change if membranes were reduced with sodium dithionite and then treated with iodoacetamide. A change in relative mobility of some of these polypeptides seemed to occur with membrane delipidation. The proteins of the fraction appear to be glycoproteins as indicated by their simultaneous staining for protein and carbohydrate and the parallel sensitivity to trypsin of both stains. The apparent molecular weights by sodium dodecylsulphate gel electrophoresis of the proteins (glycoproteins) were: 63 000, 40 000 and 17 000. Similar protein patterns were obtained by extraction of the membranes with EDTA and non-ionic detergents. Lipid and nucleotide material were also found in the “soluble” fraction.The “soluble” fraction showed by gel filtration on Sephadex G-200 the existence of different states of aggregation. These states of aggregation revealed the same electrophoretic pattern of proteins, which seemingly corresponded to that of the original fraction (i.e. three protein groups with relative mobilities 0.65, 0.80 and 1.0). Treatment of the samples under different conditions with 1% dodecylsulphate (supplemented or not with 0.5% β-mercaptoethanol) failed to completely dissociate the fraction as shown by Sephadex filtration.     

The res (restored cell structure by salinity) tomato mutant reveals the role of the DEAD-box RNA helicase SlDEAD39 in plant development and salt response

Increasing evidences highlight the importance of DEAD-box RNA helicases in plant development and stress responses. In a previous study, we characterized the tomato res mutant (restored cell structure by salinity), showing chlorosis and development alterations that reverted under salt-stress conditions. Map-based cloning demonstrates that RES gene encodes SlDEAD39, a chloroplast-targeted DEAD-box RNA helicase. Constitutive expression of SlDEAD39 complements the res mutation, while the silencing lines had a similar phenotype than res mutant, which is also reverted under salinity. Functional analysis of res mutant proved SlDEAD39 is involved in the in vivo processing of the chloroplast, 23S rRNA, at the hidden break-B site, a feature also supported by in vitro binding experiments of the protein. In addition, our results show that other genes coding for chloroplast-targeted DEAD-box proteins are induced by salt-stress, which might explain the rescue of the res mutant phenotype. Interestingly, salinity restored the phenotype of res adult plants by increasing their sugar content and fruit yield. Together, these results propose an unprecedented role of a DEAD-box RNA helicase in regulating plant development and stress response through the proper ribosome and chloroplast functioning, which, in turn, represents a potential target to improve salt tolerance in tomato crops.     

Black Yeast Biota in the Mangrove, in Search of the Origin of the Lethargic Crab Disease (LCD)

Knowledge of natural ecology is essential for a better understanding of pathogenicity and opportunism in black yeast-like fungi. Although etiological agents of diseases caused by these fungi are supposed to originate from the environment, their isolation from nature is difficult. This is probably due to their oligotrophic nature, low competitive ability, and, overall, insufficient data on their natural habitat. We obtained environmental samples from mangrove areas where mortalities by lethargic crab disease (LCD) are reported and areas without disease recorded. Isolation of chaetothyrialean black yeasts and relatives was performed using a highly selective protocol. Species-specific primers were used to determine if these isolates represented Exophiala cancerae or Fonsecaea brasiliensis, two proven agents of LCD, in order to test hypotheses about the origin of the disease. Isolates, identified by morphology as Fonsecaea- or Exophiala-like, were tested specific diagnostic markers for the fungi associated with LCD. Although several black fungi were isolated, the main causative agent of the LCD, E. cancerae, was not found. Molecular markers for F. brasiliensis revealed 10 positive bands for isolates from biofilms on mangrove leaves, branches, and aerial roots, of which four were confirmed by ITS sequencing. The absence of E. cancerae in environmental samples suggests that the species is dependent on the crab, as a genuine pathogen, different from F. brasiliensis, which is probably not dependent on the host species, U. cordatus. However, we did not attempt isolation from the marine water, which may represent the pathway of dispersion of the black yeast species between neighbor mangroves.