title: Further ultrastructural characterization of the intranuclear ring-shaped bodies of the plant Lacandonia schismatica.
abstract: Ring-shaped bodies are found in the nucleus of Lacandonia schismatica, a rare plant with the sexual organs inverted. They are 0.5-microm-diameter structures that present an electron-dense external ring surrounding a central core. Ultrastructural studies indicate that these bodies contain RNA. The external ring is labeled with antibodies against small nuclear ribonucleoproteins, suggesting that they may be involved in pre-mRNA metabolism. In the present work we further characterized these intranuclear ring-shaped structures by serial-sectioning analysis. Moreover, we tested the presence of additional molecular elements related to pre-mRNA metabolism, such as SR proteins and poly(A)(+) RNA, using immunoelectron microscopy and ultrastructural in situ hybridization. Our results show that these nuclear bodies are spherical. They contain SR proteins involved in splicing and postsplicing events and little to no poly(A)(+) RNA. We also found similar nuclear bodies in other plant and animal species. Therefore, ring-shaped bodies in L. schismatica are spherical, highly compartmentalized nuclear structures that may be involved in pre-mRNA metabolism.
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias, UNAM, Circuito Exterior, México, D.F, 04510, México
authors.forename: L T
authors.initials: LT
authors.lastname: Agredano-Moreno
authors.forename: M A
authors.initials: MA
authors.lastname: González-Jiménez
authors.forename: M
authors.initials: M
authors.lastname: de Lourdes Segura-Valdez
authors.forename: E
authors.initials: E
authors.lastname: Ubaldo
authors.forename: C H
authors.initials: CH
authors.lastname: Ramos
authors.forename: E
authors.initials: E
authors.lastname: Martínez
authors.forename: L F
authors.initials: LF
authors.lastname: Jiménez-García
mesh_terms: D002467:Cell Nucleus / Q000648:ultrastructure*; D004247:DNA / Q000378:metabolism; D017403:In Situ Hybridization; D016253:Microscopy, Immunoelectron; D018521:Plant Physiological Phenomena; D010944:Plants / Q000235:genetics / Q000648:ultrastructure*; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D012313:RNA; D004247:DNA