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Ana María Rojas

Publications and source records attributed to Ana María Rojas.

3 recordsLinked to original sources

A framework for computational and experimental methods: identifying dimerization residues in CCR chemokine receptors.

Solving relevant biological problems requires answering complex questions. Addressing such questions traditionally implied the design of time-consuming experimental procedures which most of the time are not accessible to average-sized laboratories. The current trend is to move towards a multidisciplinary approach integrating both theoretical knowledge and experimental work. This combination creates a powerful tool for shedding light on biological problems. To illustrate this concept, we present here a descriptive example of where computational methods were shown to be a key aspect in detecting crucial players in an important biological problem: the dimerization of chemokine receptors. Using evolutionary based sequence analysis in combination with structural predictions two CCR5 residues were selected as important for dimerization and further validated experimentally. The experimental validation of computational procedures demonstrated here provides a wealth of valuable information not obtainable by any of the individual approaches alone.

Amino Acid Sequence↗

Erwinia toletana sp. nov., associated with Pseudomonas savastanoi-induced tree knots.

Gram-negative bacteria were isolated from knots induced by Pseudomonas savastanoi in olive trees (Olea europaea L.). A total of nine endophytic bacterial strains were isolated, each from inside a different tree knot. Biochemical characterization indicated that all the strains belong to the family Enterobacteriaceae. Phylogenetic analyses of the 16S rRNA genes of these novel isolates revealed that they formed a homogeneous cluster within Erwinia species. DNA signatures of these isolates were identical to those described for the genus Erwinia. The strains formed a homogeneous group as shown by DNA-DNA hybridization analysis and numerical analysis of phenotypic data, clearly differentiated from all species of Erwinia with validly published names. The data provide strong evidence of the differentiation of these strains from the most closely related species. Therefore, these isolates represent a novel species, for which the name Erwinia toletana sp. nov. is proposed. The isolates are available at CFBP, CECT and ATCC. The G+C content is 52+/-0.5 mol%. The type strain is CFBP 6631(T) (=A37(T)=ATCC 700880(T)=CECT 5263(T)).

Bacterial Typing Techniques↗

Dynamic rheological measurements and drug release kinetics in swollen scleroglucan matrices.

The structure of scleroglucan gel matrices was characterized by dynamic rheological studies. The results were compared with the release kinetics of theophylline in analogous samples using a Franz diffusion cell, fitting the drug release data with a semi-empirical power law. Dynamic rheology gave information about the viscous and elastic components (loss and storage moduli, respectively) of the gel which could influence the drug-release profiles. Scleroglucan gels showed two structural transitions within the gel regime that coincided with changes in the release pattern. It was found that the introduction of 0.4% (w/w) of theophylline decreased the loss and storage moduli in the 2% (w/w) scleroglucan gels by 50%. The influence of the same wt.% theophylline in other gels was strongly dependent on the gel concentration. These results demonstrated the value of rheological studies to detect matrix structural changes produced by the inclusion of drugs which may modify the drug-release profile.

Chemistry, Pharmaceutical↗