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Nuclear Ribosomal Internal Transcribed Spacer (nuclear + ribosomal_internal_transcribed_spacer)
Selected AbstractsGenetic Identification of Pelagic Shark Body Parts for Conservation and Trade MonitoringCONSERVATION BIOLOGY, Issue 4 2002Mahmood Shivji Difficulties with the identification of many commonly fished sharks and their body parts has resulted in a global dearth of catch and trade information, making reliable assessment of exploitation effects and conservation needs for individual species nearly impossible. We developed and tested a highly streamlined molecular genetic approach based on species-specific, polymerase-chain-reaction primers in an eight-primer multiplex format to discriminate simultaneously between body parts from six shark species common in worldwide pelagic fisheries. The species-specific primers are based on DNA sequence differences among species in the nuclear ribosomal internal transcribed spacer 2 locus. The primers and multiplex format accurately and sensitively distinguished samples from each of three lamnid ( Isurus oxyrinchus, Isurus paucus, and Lamna nasus) and three carcharhinid ( Prionace glauca, Carcharhinus obscurus, and Carcharhinus falciformis) species from all but one other shark species encountered in the North Atlantic fishery. Furthermore, the three lamnid primers were robust enough in their discriminatory power to be useful for species diagnosis on a global scale. Preliminary testing of dried fins from Asian and Mediterranean commercial markets suggests that our genetic approach will be useful for determining the species of origin of detached fins, thus allowing the monitoring of trade in shark fins for conservation assessment. Our approach will also facilitate detection of products from protected and other at-risk shark species and may prove useful as a model for development of the high-throughput, genetic, species-diagnosis methods typically required in conservation and management contexts. Resumen: La conservación y manejo de tiburones fundamentado a nivel de especie es una necesidad imperativa debido a la creciente demanda de aletas de tiburón y el reconocimiento de que las especies individuales de tiburones responden de manera distinta a la explotación. Las dificultades para la identificación de muchos tiburones capturados comúnmente, así como de partes de su cuerpo, han resultado en una escasez global de información sobre capturas y comercialización, haciendo casi imposible el poder realizar evaluaciones de los efectos de la explotación y de las necesidades de conservación. Desarrollamos y evaluamos un método altamente estilizado de genética molecular basado en detonadores de la reacción en cadena de la polimerasa, especie-específicos, en un formato múltiple de ocho detonadores para discriminar simultáneamente entre las partes del cuerpo de seis especies de tiburones provenientes de pesquerías pelágicas mundiales comunes. Los detonadores especie-específicos están basados en diferencias en las secuencias de ADN entre especies del locus espaciador 2 nuclear, ribosomal, transcrito. Los detonadores y el formato múltiple distinguen muestras con precisión y sensitividad de cada uno de los tres lámnidos ( Isurus oxyrinchus, Isurus paucus y Lamna nasus) y tres especies de carcarínidos ( Prionace glauca, Carcharhinus obscurus y Carcharhinus falciformis) especies todas encontradas en las pesquerías de Norteamérica, excepto una. Mas aún, los detonadores de los tres lamnidos fueron lo suficientemente robustos en su poder discriminante como para ser usados para el diagnóstico de especies a escala mundial. Las pruebas preliminares de aletas secas de los mercados comerciales de Asia y el Mediterráneo sugieren que nuestro método genético puede ser útil para determinar la especie de origen de las aletas separadas, permitiendo así usar el monitoreo de las aletas de tiburón para evaluaciones de conservación. Nuestro método también podría facilitar la detección de productos provenientes de especies protegidas o en riesgo y podría resultar útil como un modelo para el desarrollo de métodos genéticos de alto rendimiento para el diagnóstico de especies, métodos típicamente requeridos en los contextos de conservación y manejo. [source] The teleomorph of Chalara fraxinea, the causal agent of ash diebackFOREST PATHOLOGY, Issue 5 2009T. Kowalski Summary Ash dieback, caused by the pathogen Chalara fraxinea, is an emerging lethal disease of Fraxinus excelsior, threatening the host species in large parts of Europe. The ascomycete Hymenoscyphus albidus (Helotiaceae, Helotiales) was identified as the teleomorph of C. fraxinea by culturing from ascospores, morphological comparison and nuclear ribosomal internal transcribed spacer (ITS) sequencing. [source] The colonization history of Olea europaea L. in Macaronesia based on internal transcribed spacer 1 (ITS-1) sequences, randomly amplified polymorphic DNAs (RAPD), and intersimple sequence repeats (ISSR)MOLECULAR ECOLOGY, Issue 7 2000J. Hess Abstract Phylogenetic relationships in the Olea europaea complex and the phylogeography of 24 populations of the Macaronesian olive (O. europaea ssp. cerasiformis) were assessed by using three molecular markers: nuclear ribosomal internal transcribed spacer 1 (ITS-1) sequences, randomly amplified polymorphic DNAs (RAPD), and intersimple sequence repeats (ISSR). Parsimony analysis of the ITS-1 sequences and Neighbour-joining (NJ) analyses of RAPD and ISSR banding variation revealed four major lineages in the O. europaea complex: (1) ssp. cuspidata; (2) ssp. cerasiformis from Madeira; (3) ssp. laperrinei; and (4) ssp. cerasiformis from the Canary Islands plus ssp. europaea. These results provide unequivocal support for two independent dispersal events of Olea to the Madeira and Canary Islands. Molecular and morphological evidence led to recognition of two separate olive taxa in Macaronesia, to date included in ssp. cerasiformis. NJ analyses of the combined RAPD and ISSR data suggest that the colonization of the Canaries by O. europaea may have followed an east to west stepping-stone model. An interisland dispersal sequence can be recognized, starting from the continent to Fuerteventura, Gran Canaria, Tenerife, La Gomera, and finally La Palma. High dispersal activity of the lipid-rich Olea fruits by birds in the Mediterranean region is congruent with multiple dispersal of olives to Macaronesia and successive colonization of the archipelagos. The observation of strong genetic isolation between populations of different islands of the Canary Islands suggests, however, that subsequent interisland dispersal and establishment has been very rare or may not have occurred at all. [source] Disentangling the bindweeds: hybridization and taxonomic diversity in British Calystegia (Convolvulaceae)BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009JACQUELINE M. BROWN Calystegia is taxonomically complex. More than 65 taxa are currently recognized, but species circumscription is problematic, geographical intergradation between taxa is common and hybridization between species is known to occur. In this study, the nuclear ribosomal internal transcribed spacer 1 region (ITS1) was used to investigate the extent to which interspecific hybridization has contributed to the generation of taxonomic diversity in the C. sepium complex of the genus. Focusing principally on taxa that occur in Britain and their putative relatives, patterns of infra-individual ITS1 variation were examined by direct sequencing and cloning. Direct sequencing of the ITS region of 58 accessions representing 11 taxa and one hybrid revealed 22 variable positions that collectively defined 14 ribotypes. Diagnostic and invariant ribotypes lacking polymorphisms were found in C. sepium ssp. sepium, C. sepium ssp. limnophila, C. silvatica ssp. silvatica, C. pellita, C. pubescens and C. soldanella. Three ribotypes were recovered in C. sepium ssp. americana, two of which lacked polymorphisms, whereas the third exhibited two polymorphic sites. Calystegia sepium ssp. roseata, C. sepium ssp. spectabilis, C. silvatica ssp. disjuncta, C. pulchra and C. × howittiorum were each characterized by taxon-specific polymorphisms in the ITS1 region. In each case, the polymorphisms observed were consistent with the co-occurrence in the genome of nonpolymorphic ribotypes that were observed in other taxa. This observation is supported by cloning of the ITS region and is consistent with a hybrid origin for the taxa in which they occur. The hypotheses of hybridity proposed are further shown to be congruent with other data, notably morphology. This study suggests that taxonomic diversity within the C. sepium complex may have been promoted by hybridization. For at least some of the taxa investigated, it is at least possible that sympatry may have been achieved anthropogenically, through the introduction of taxa into cultivation. The processes revealed in this study may help to explain some of the taxonomic complexity observed in the genus more widely, although this remains to be tested. © 2009 The Natural History Museum, London, Botanical Journal of the Linnean Society, 2009, 160, 388,401. [source] | ||||||||||