RESUMO
Blue mold caused by Penicillium spp. is the most important postharvest disease of apple in Uruguay. Fourteen isolates of Penicillium were recovered from rotten apple and pear fruit with blue mold symptoms, and from water from flotation tanks in commercial apple juice facilities. Phenotypic identification to species level was performed, and the isolates were tested for sensitivity to commonly used postharvest fungicides. Genetic characterization of the isolates was performed with restriction fragment length polymorphism of the region including the internal transcribed spacer (ITS) ITS1 and ITS2 and the 5.8SrRNA gene (ITS1-5.8SrRNA gene-ITS2) ribosomal DNA region and with random amplified polymorphic DNA (RAPD) primers. Both techniques were able to differentiate these isolates at the species level. RAPD analysis proved to be an objective, rapid, and reliable tool to identify Penicillium spp. involved in blue mold of apple. In all, 11 isolates were identified as Penicillium expansum and 3 as P. solitum. This is the first report of P. solitum as an apple pathogen in Uruguay.
RESUMO
The accumulation of Hg, Zn, and Cu was evaluated in mangrove sediments located between a large, 20-years-old landfill and waters of Guanabara Bay (southeast Brazil). The contamination history of the area provides substantial evidence that metal accumulation in the study site is influenced by past metal emissions from multiple sources (e.g. contaminated rivers and the landfill surrounding the site). At the southern part of the site, metal levels are up to 890 ng g(-1) Hg, 850 microg g(-1) Zn, and 58 microg g(-1) Cu. Enrichment factors and excess (background-deducted) concentration inventories show a high spatial variability of metal contamination and storage in the site, with differences often by a factor higher than two within a sampling station and higher than five between sampling stations. These contrasts are attributable to a coupling between spatial variability of anthropogenic metal input and metal behavior and retention within the sediments. Results indicate that during the last few decades mangrove sediments retained a substantial part of metal emissions to the site, probably reducing the metal transport to Guanabara Bay waters, and suggest the suitability of mangrove ecosystems as physical and biogeochemical barriers to metal contaminant transport.
Assuntos
Poluição Ambiental , Resíduos Perigosos , Metais/análise , Gerenciamento de Resíduos/métodos , Brasil , Cobre/análise , Sedimentos Geológicos , Mercúrio/análise , Fatores de Tempo , Zinco/análiseRESUMO
Intrathymic maturation of thymocytes is essential for the proper formation of T-cell repertoire. This process involves two major biochemical pathways, one initiated by the recognition of MHC/peptide by the T-cell receptor and the other mediated by glucocorticoids. These hormones seem to affect thymocyte maturation by increasing the threshold of TCR-mediated positive and negative selection, and by inducing apoptosis of nonselected thymocytes. We have previously reported that an SV40-immortalized murine thymic epithelial cell line, namely 2BH4, was able to protect thymocytes from dexamethasone-induced apoptosis. Here we show that this protection is independent of cell-to-cell contact and does not seem to involve a Bcl-2-mediated resistance, since incubation of thymocytes with 2BH4 cells or its supernatant does not interfere with the levels of this antiapoptotic molecule. The protection conferred by 2BH4 cells, or by a primary culture of thymic stromal cells, is specific for the CD4(+)CD8(-) and CD4(-)CD8(+) single-positive thymocytes, whereas the broad-spectrum caspase inhibitor z-VAD-fmk blocks apoptosis induced by dexamethasone in all thymocyte subpopulations. Our results suggest that positively selected single-positive thymocytes are still susceptible to glucocorticoid-induced apoptosis but are protected from it through the action of a heat-stable protein(s) released by thymic stromal cells.