Distribution and ecological risk of metals in an urban natural protected area in the Riviera Maya, Mexico.

Urbanization can negatively impact natural protected areas near or surrounded by cities, and such impacts include untreated wastewater discharge, leachates from dumpsters, e-waste, and road dust. In this research, we show that not only large cities with industry are prone to be polluted, but also young touristic cities with high population increase rate can suffer from urban contamination. We evaluated metal pollution in a natural protected area within a 50-year-old city without conventional industry that was likely contaminated by the urban sprawl around the protected area. We tested water, zooplankton, sediment and plant samples for metallic elements to evaluate their bioaccumulation in zooplankton, enrichment factors and geoaccumulation index values in sediments, and translocation factors in plants. Finally, we evaluated the ecological risk due to metal contamination. Metals at levels above our detection limit (20 µg/L) were not found in the water and zooplankton samples. The sediments and plants in the storm drain section of the protected area had a greater concentration of metals and wastewater indicators (coliforms) than those in the rest of the lagoon. Moreover, signs of Al, Cu, Ni, Zn, Cr, Pb, and Ti contamination were found in the plant tissues. We estimated that the ecological risk of this natural protected area surrounded by the city of Cancun (Mexico) ranged from mild to strong, with Zn being the metal of most concern. The results highlight that young touristic cities around the world will endure contamination from urban sources; signs or early warnings of contamination must be identified to prevent and resolve such issues.

Biochemical and proteomic analysis of spliceosome factors interacting with intron-1 of human papillomavirus type-16.

The human papillomavirus type 16 (HPV-16) E6/E7 spliced transcripts are heterogeneously expressed in cervical carcinoma. The heterogeneity of the E6/E7 splicing profile might be in part due to the intrinsic variation of splicing factors in tumor cells. However, the splicing factors that bind the E6/E7 intron 1 (In-1) have not been defined. Therefore, we aimed to identify these factors; we used HeLa nuclear extracts (NE) for in vitro spliceosome assembly. The proteins were allowed to bind to an RNA/DNA hybrid formed by the In-1 transcript and a 5'-biotinylated DNA oligonucleotide complementary to the upstream exon sequence, which prevented interference in protein binding to the intron. The hybrid probes bound with the nuclear proteins were coupled to streptavidin magnetic beads for chromatography affinity purification. Proteins were eluted and identified by mass spectrometry (MS). Approximately 170 proteins were identified by MS, 80% of which were RNA binding proteins, including canonical spliceosome core components, helicases and regulatory splicing factors. The canonical factors were identified as components of the spliceosomal B-complex. Although 35-40 of the identified factors were cognate splicing factors or helicases, they have not been previously detected in spliceosome complexes that were assembled using in vivo or in vitro models.