CATALYTIC PROPERTIES OF THE EUKARYOTIC EXOSOME

The eukaryotic exosome complex is built around the backbone of a 9‑subunit ring similar to phosporolytic ribonucleases such as RNase PH and polynucleotide phosphorylase (PNPase). Unlike those enzymes, the ring is devoid of any detectable catalytic activities, with the possible exception of the plant version of the complex. Instead, the essential RNA decay capability is supplied by associated hydrolytic ribonucleases belonging to the Dis3 and Rrp6 families. Dis3 proteins are endowed with two different activities: the long known processive 3′‑5′ exonucleolytic one and the recently discovered endonucleolytic one. Rrp6 proteins are distributive exonucleases. This chapter will review the current knowledge about the catalytic properties of theses nucleases and their interplay within the exosome holocomplex

Some experiences with acetic orcein in animal chromosomes

[ES] La orceína acética de La Cour ha sido utilizada con éxito como fijador-colorante para cromosomas animales. Como solución tipo se recomienda la de orceína al 2% en ácido acético al 45%. Para el estudio cromosómico es necesario el reblandecimiento de los tejidos y la separación de sus células, lo que se consigue añadiendo 1 c.c. de ácido clorhídrico normal a 9 c.c. de la solución anterior, colocando el tejido en la mezcla y calentando sin que llegue a hervir.Peer reviewe