title: Molecular characterization of 5S ribosomal RNA genes and transcripts in the protozoan parasite Leishmania major.
abstract: Eukaryotic 5S rRNA, synthesized by RNA polymerase III (Pol III), is an essential component of the large ribosomal subunit. Most organisms contain hundreds of 5S rRNA genes organized into tandem arrays. However, the genome of the protozoan parasite Leishmania major contains only 11 copies of the 5S rRNA gene, which are interspersed and associated with other Pol III-transcribed genes. Here we report that, in general, the number and order of the 5S rRNA genes is conserved between different species of Leishmania. While in most organisms 5S rRNA genes are normally associated with the nucleolus, combined fluorescent in situ hybridization and indirect immunofluorescence experiments showed that 5S rRNA genes are mainly located at the nuclear periphery in L. major. Similarly, the tandemly repeated 5S rRNA genes in Trypanosoma cruzi are dispersed throughout the nucleus. In contrast, 5S rRNA transcripts in L. major were localized within the nucleolus, and scattered throughout the cytoplasm, where mature ribosomes are located. Unlike other rRNA species, stable antisense RNA complementary to 5S rRNA is not detected in L. major.
authors.affiliation: Unidad de Biomedicina,Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Moreno-Campos
authors.affiliation: Unidad de Biomedicina,Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
authors.forename: Luis E
authors.initials: LE
authors.lastname: Florencio-Martínez
authors.affiliation: Unidad de Biomedicina,Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
authors.forename: Tomás
authors.initials: T
authors.lastname: Nepomuceno-Mejía
authors.affiliation: Unidad de Biomedicina,Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
authors.forename: Saúl
authors.initials: S
authors.lastname: Rojas-Sánchez
authors.affiliation: Unidad de Biomedicina,Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Vélez-Ramírez
authors.affiliation: Unidad de Biomedicina,Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
authors.forename: Norma E
authors.initials: NE
authors.lastname: Padilla-Mejía
authors.affiliation: Unidad de Biomedicina,Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
authors.forename: Elisa
authors.initials: E
authors.lastname: Figueroa-Angulo
authors.affiliation: Departamento de Biomedicina Molecular,Centro de Investigación y de Estudios Avanzados del IPN,Av. IPN 2508,México, D.F., CP 07360,México.
authors.forename: Rebeca
authors.initials: R
authors.lastname: Manning-Cela
authors.affiliation: Unidad de Biomedicina,Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Av. De los Barrios 1,Col. Los Reyes Iztacala,Tlalnepantla,Edo. de México,CP 54090,México.
authors.forename: Santiago
authors.initials: S
authors.lastname: Martínez-Calvillo
mesh_terms: D000818:Animals; D001483:Base Sequence; D015870:Gene Expression; D020459:Genes, rRNA; D018503:Genome, Protozoan; D017404:In Situ Hybridization, Fluorescence; D018320:Leishmania major / Q000235:genetics*; D012320:RNA Polymerase III; D016053:RNA, Protozoan / Q000235:genetics*; D012341:RNA, Ribosomal, 5S / Q000235:genetics* / Q000302:isolation & purification; D014349:Trypanosoma cruzi
chemical_list: D016053:RNA, Protozoan; D012341:RNA, Ribosomal, 5S; D012320:RNA Polymerase III
keywords: 
                 Leishmania
              ; 5S rRNA; Pol III transcription; gene expression