A functional genomics project has been initiated to approach the molecular characterization of the main biological and agronomical traits of citrus. As a key part of this project, a citrus EST collection has been generated from 25 cDNA libraries covering different tissues, developmental stages and stress conditions. The collection includes a total of 22,635 high-quality ESTs, grouped in 11,836 putative unigenes, which represent at least one third of the estimated number of genes in the citrus genome. Functional annotation of unigenes which have Arabidopsis orthologues (68% of all unigenes) revealed gene representation in every major functional category, suggesting that a genome-wide EST collection was obtained. A Citrus clementina Hort. ex Tan. cv. Clemenules genomic library, that will contribute to further characterization of relevant genes, has also been constructed. To initiate the analysis of citrus transcriptome, we have developed a cDNA microarray containing 12,672 probes corresponding to 6875 putative unigenes of the collection. Technical characterization of the microarray showed high intra- and inter-array reproducibility, as well as a good range of sensitivity. We have also validated gene expression data achieved with this microarray through an independent technique such as RNA gel blot analysis.

SUMMARYThe importance of recovering waste materials generated by industrialised societies is mainly due to the environmental impact that they have, and one of the principal problems is the presence of end of life tyres. The use of waste microfibre obtained from shredded tyres as reinforcement in polypropylene matrices offers an interesting opportunity for recycling of the waste microfibre, in order to obtain 'value added products' from polypropylene (PP)/waste microfibre tyre composites. The microfibres obtained from shredded tyres were used as a reinforcing material in compositions with polypropylene (PP). The blending proportions were: (1) 10% microfibre 90% PP; (2) 20% microfibre, 80% PP; (3) 30% microfibre, 70% PP; (4) 40% microfibre, 60% PP, (5) 50% microfibre, 50% PP and (6) 80% microfibre, 20% PP. The mechanical and thermal properties were analyzed. In this case polypropylene mixed with polyamide (PA) microfibres show a decrease in tensile strength and elongation at break, however, impact strength and Vicat Softening temperature values increase with polyamide microfibre content. Continuity in the matrix phase was observed by scanning electron microscopy up to loadings of 40% microfibre.

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