Edited by Karin Musier-Forsyth Eukaryotic ribosomal biogenesis is a high-energy-demanding and complex process that requires hundreds of transacting factors to dynamically build the highly-organized 40S and 60S subunits. Each ribonucleoprotein complex comprises specific rRNAs and ribosomal proteins that are organized into functional domains. The RNA exosome complex plays a crucial role as one of the pre-60S-processing factors, because it is the RNase responsible for processing the 7S pre-rRNA to the mature 5.8S rRNA. The yeast pre-60S assembly factor Nop53 has previously been shown to associate with the nucleoplasmic pre-60S in a region containing the "foot" structure assembled around the 3 end of the 7S pre-rRNA. Nop53 interacts with 25S rRNA and with several 60S assembly factors, including the RNA exosome, specifically, with its catalytic subunit Rrp6 and with the exosome-associated RNA helicase Mtr4. Nop53 is therefore considered the adaptor responsible for recruiting the exosome complex for 7S processing. Here, using proteomics-based approaches in budding yeast to analyze the effects of Nop53 on the exosome interactome, we found that the exosome binds pre-ribosomal complexes early during the ribosome maturation pathway. We also identified interactions through which Nop53 modulates exosome activity in the context of 60S maturation and provide evidence that in addition to recruiting the exosome, Nop53 may also be important for positioning the exosome during 7S processing. On the basis of these findings, we propose that the exosome is recruited much earlier during ribosome assembly than previously thought, suggesting the existence of additional interactions that remain to be described.

The Linear sweep voltammetry method (LSP) of a common pesticide such as chlorpyrifos (CP) an organophosphate pesticide (OPP) in white (Allium cepa L.) and green onions (Allium fistulosum L.) was investigated. A hanging mercury drop electrode (HMDE) Ag/AgCl was used as reference electrode and platinum as a counter electrode. The OPP was extracted from the onion through liquid-liquid partition using acetone/dichloromethane as the solvent. Validated method was compared with GC/ECD as a reference method. CP concentration was not different between the two analytical techniques; the analysis was performed with a confidence level of 90%, corresponding to the polarographic method. CP concentration was 0.8400 ± 0.062 ppm in Allium cepa and 0.062 ± 0.300 ppm in Allium fistulosum L. These values exceed the ADI and ARD values for chlorpyrifos established by current regulations.

Dedicado a mi hermana Jhohana, te doy gracias infinitas por todas aquellas cosas que hiciste y dejaste de hacer por mí a lo largo de tu vida, por ser comprensiva y corregirme cuando era necesario. Siempre fuiste un ejemplo de trabajo, tenacidad e inteligencia, nunca te dejaste vencer en las dificultades, recuerdo que decías: "mañana será un día mejor". Cuando decidí venir a Brasil, fuiste la primera entusiasta y me brindaste tu apoyo moral y financiero. Recuerdo tu sonrisa y tuímpetu al creer en mí, sabias, más que yo, que lo iba a lograr. Espero que tus enseñanzas sean manifestadas en cada paso que dé, que mi vida sea una representación del legado dejaste en mí y en todas y cada una de las personas que te rodearon. siempre te recordaré, te amo y te amaré inmensamente.