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Genetic evidence for the role of GDP-mannose in plant ascorbic acid (vitamin C) biosynthesis

REA Auditado

Vitamin C (L-ascorbic acid; AsA) acts as a potent antioxidant and cellular reductant in plants and animals. AsA has long been known to have many critical physiological roles in plants, yet its biosynthesis is only currently being defined. A pathway for AsA biosynthesis that features GDP-mannose and L-galactose has recently been proposed for plants. We have isolated a collection of AsA-deficient mutants of Arabidopsis thaliana that are valuable tools for testing of an AsA biosynthetic pathway.

Tema: general: 

• Ciencias de la Salud›Medicina›Neurología

Habituation of Salmonella spp. at Reduced Water Activity and Its Effect on Heat Tolerance

REA Auditado

The effect of habituation at reduced water activity (a(w)) on heat tolerance of Salmonella spp. was investigated. Stationary-phase cells were exposed to a(w) 0.95 in broths containing glucose-fructose, sodium chloride, or glycerol at 21 degrees C for up to a week prior to heat challenge at 54 degrees C. In addition, the effects of different a(w)s and heat challenge temperatures were investigated. Habituation at a(w) 0.95 resulted in increased heat tolerance at 54 degrees C with all solutes tested. The extent of the increase and the optimal habituation time depended on the solute used.

Tema: general: 

• Ciencias de la Salud›Medicina›Neurología

Matched Filters, Mate Choice and the Evolution of Sexually Selected Traits

REA Auditado

Background
Fundamental for understanding the evolution of communication systems is both the variation in a signal and how this affects the behavior of receivers, as well as variation in preference functions of receivers, and how this affects the variability of the signal. However, individual differences in female preference functions and their proximate causation have rarely been studied.
Methodology/Principal Findings
Calling songs of male field crickets represent secondary sexual characters and are subject to sexual selection by female choice.

Tema: general: 

• Ciencias de la Salud›Medicina›Neurología

suc1 is an essential gene involved in both the cell cycle and growth in fission yeast

REA Auditado

The gene suc1 encodes a product which suppresses certain temperature sensitive mutants of the cell cycle control gene cdc2 of Schizosaccharomyces pombe. Mutants in the suc1 gene or over-expression of its product leads to delays in mitotic and meiotic nuclear division. Deletion of the suc1 gene is lethal and generates some cells blocked in the cell cycle and others impaired in cellular growth. It is likely that the suc1 gene product binds and forms unstable complexes with the cdc2 protein kinase and with other proteins necessary for the cell cycle and cellular growth.

Tema: general: 

• Ciencias de la Salud›Medicina›Neurología

Plant Enzymes but not Agrobacterium VirD2 Mediate T-DNA Ligation In Vitro

REA Auditado

Agrobacterium tumefaciens, a gram-negative soil bacterium, transfers DNA to many plant species. In the plant cell, the transferred DNA (T-DNA) is integrated into the genome. An in vitro ligation-integration assay has been designed to investigate the mechanism of T-DNA ligation and the factors involved in this process. The VirD2 protein, which is produced in Agrobacterium and is covalently attached to T-DNA, did not, under our assay conditions, ligate T-DNA to a model target sequence in vitro. We tested whether plant extracts could ligate T-DNA to target oligonucleotides in our test system.

Tema: general: 

• Ciencias de la Salud›Medicina›Neurología

Sample Size and Precision in NIH Peer Review

REA Auditado

The Working Group on Peer Review of the Advisory Committee to the Director of NIH has recommended that at least 4 reviewers should be used to assess each grant application. A sample size analysis of the number of reviewers needed to evaluate grant applications reveals that a substantially larger number of evaluators are required to provide the level of precision that is currently mandated. NIH should adjust their peer review system to account for the number of reviewers needed to provide adequate precision in their evaluations.

Tema: general: 

• Ciencias de la Salud›Medicina›Neurología

Complementation of the mpg1 mutant phenotype in Magnaporthe grisea reveals functional relationships between fungal hydrophobins.

REA Auditado

The functional relationship between fungal hydrophobins was studied by complementation analysis of an mpg1(-) gene disruption mutant in Magnaporthe grisea. MPG1 encodes a hydrophobin required for full pathogenicity of the fungus, efficient elaboration of its infection structures and conidial rodlet protein production. Seven heterologous hydrophobin genes were selected which play distinct roles in conidiogenesis, fruit body development, aerial hyphae formation and infection structure elaboration in diverse fungal species.

Tema: general: 

• Ciencias de la Salud›Medicina›Neurología

Does Sex Trade with Violence among Genotypes in Drosophila melanogaster?

REA Auditado

The evolutionary forces shaping the ability to win competitive interactions, such as aggressive encounters, are still poorly understood. Given a fitness advantage for competitive success, variance in aggressive and sexual display traits should be depleted, but a great deal of variation in these traits is consistently found. While life history tradeoffs have been commonly cited as a mechanism for the maintenance of variation, the variability of competing strategies of conspecifics may mean there is no single optimum strategy.

Tema: general: 

• Ciencias de la Salud›Medicina›Neurología

Children's Perceptions of Rainforest Biodiversity: Which Animals Have the Lion's Share of Environmental Awareness?

REA Auditado

Globally, natural ecosystems are being lost to agricultural land at an unprecedented rate. This land-use often results in significant reductions in abundance and diversity of the flora and fauna as well as alterations in their composition. Despite this, there is little public perception of which taxa are most important in terms of their total biomass, biodiversity or the ecosystem services they perform. Such awareness is important for conservation, as without appreciation of their value and conservation status, species are unlikely to receive adequate conservation protection.

Tema: general: 

• Ciencias de la Salud›Medicina›Neurología

Practical uses for ecdysteroids in mammals including humans: an update

REA Auditado

Ecdysteroids are widely used as inducers for gene-switch systems based on insect ecdysteroid receptors and genes of interest placed under the control of ecdysteroid-response elements. We review here these systems, which are currently mainly used in vitro with cultured cells in order to analyse the role of a wide array of genes, but which are expected to represent the basis for future gene therapy strategies. Such developments raise several questions, which are addressed in detail.

Tema: general: 

• Ciencias de la Salud›Medicina›Neurología