Search

[EN] Circular RNAs (circRNAs) are regulatory molecules involved in the modulation of gene expression. Although originally assumed as non-coding RNAs, recent studies have evidenced that animal circRNAs can act as translatable transcripts. The study of plant-circRNAs is incipient, and no autonomous coding plant-circRNA has been described yet. Viroids are the smallest plant-pathogenic circRNAs known to date. Since their discovery 50 years ago, viroids have been considered valuable systems for the study of the structure-function relationships in RNA, essentially because they have not been shown to have coding capacity. We used two pathogenic circRNAs (Hop stunt viroid and Eggplant latent viroid) as experimental tools to explore the coding potential of plant-circRNAs. Our work supports that the analysed viroids contain putative ORFs able to encode peptides carrying subcellular localization signals coincident with the corresponding replication-specific organelle. Bioassays in well-established hosts revealed that mutations in these ORFs diminish their biological efficiency. Interestingly, circular forms of HSVd and ELVd were found to co-sediment with polysomes, revealing their physical interaction with the translational machinery of the plant cell. Based on this evidence we hypothesize about the possibility that plant circRNAs in general, and viroids in particular, can act, under certain cellular conditions, as non-canonical translatable transcripts.

Circular RNAs (circRNAs) are regulatory molecules involved in the modulation of gene expression. Although originally assumed as non-coding RNAs, recent studies have evidenced that animal circRNAs can act as translatable transcripts. The study of plant-circRNAs is incipient, and no autonomous coding plant-circRNA has been described yet. Viroids are the smallest plant-pathogenic circRNAs known to date. Since their discovery 50 years ago, viroids have been considered valuable systems for the study of the structure-function relationships in RNA, essentially because they have not been shown to have coding capacity. We used two pathogenic circRNAs (Hop stunt viroid and Eggplant latent viroid) as experimental tools to explore the coding potential of plant-circRNAs. Our work supports that the analysed viroids contain putative ORFs able to encode peptides carrying subcellular localization signals coincident with the corresponding replication-specific organelle. Bioassays in well-established hosts revealed that mutations in these ORFs diminish their biological efficiency. Interestingly, circular forms of HSVd and ELVd were found to co-sediment with polysomes, revealing their physical interaction with the translational machinery of the plant cell. Based on this evidence we hypothesize about the possibility that plant circRNAs in general, and viroids in particular, can act, under certain cellular conditions, as non-canonical translatable transcripts.

En primer lugar, debe aclararse qué es un Parque Nacional. Esta figura acaba de cumplir en España su primer siglo de vida. Fue en el año 1916 cuando se aprobó la primera Ley de Parques Nacionales, muy novedosa para la época y pionera a nivel europeo, aunque no debemos obviar su consideración de heredera directa del previo modelo estadounidense que trajo consigo las primeras normas sobre Parques Nacionales a nivel mundial: El Parque Nacional de Yellowstone en el año 1872 y el Parque Nacional de Yosemite en el año 1890. El artículo 2 de la breve Ley de 1916 define los Parques Nacionales como: “…aquellos sitios ó parajes excepcionalmente pintorescos…”, en donde se hace respetar “…la belleza natural de sus paisajes, la riqueza de su fauna y de su flora y las particularidades geológicas é hidrológicas que encierren, evitando de este modo con la mayor eficacia todo acto de destrucción, deterioro ó desfiguración por la mano del hombre…”. Por tanto, un Parque Nacional se caracterizan por la singularidad y riqueza de su relieve, su fauna y su vegetación, lo cual lo convierten en acreedor de una especial protección. En el caso del Parque Nacional de Cabañeros, la singularidad procede de la enorme riqueza del bosque mediterráneo que alberga. Se trata de un espacio natural estrechamente vinculado a Los Montes de Toledo. Su devenir histórico, como veremos, se encuentra íntimamente ligado a ellos y a la ciudad de Toledo, que ejerció desde siempre un enorme poder sobre Los Montes que llevan su nombre. Además, haremos hincapié en dos aspectos que determinan poderosamente el discurrir de los acontecimientos en la zona: su escaso poblamiento y su agreste orografía..., First, it should be clarified what a National Park is. This figure has just fulfilled in Spain its first century of life. It was in 1916 when the first Law of National Parks was approved, very novel for the time and pioneer at European level, although we should not ignore its consideration as direct heir of the previous American model that brought with it the first regulations on National Parks at the World: Yellowstone National Park in 1872 and Yosemite National Park in 1890. Article 2 of the brief 1916 Law defines National Parks as: "... those places or exceptionally picturesque places ...", where the "natural beauty of its landscapes, the richness of its fauna and flora and the geological and hydrological particularities that they contain, avoiding in this way with the greatest effectiveness any act of destruction, deterioration or disfigurement by the hand of man ... ". Therefore, a National Park is characterized by the uniqueness and richness of its relief, its fauna and vegetation, which make it a creditor of special protection. In the case of the Cabañeros National Park, the singularity comes from the enormous wealth of the Mediterranean forest that it houses. It is a natural space closely linked to Los Montes de Toledo. Its historical development, as we shall see, is closely linked to them and to the city of Toledo, which has always exercised enormous power over the mountains that bear its name. In addition, we will emphasize two aspects that powerfully determine the course of events in the area: its sparse settlement and rough terrain...