title: Physical localization and probable transcriptional activity of 18S-5.8S-26S rRNA gene loci in some Asiatic Cymbidiums (Orchidaceae) from north-east India.
abstract: Fluorescence in situ hybridization based physical localization of 45S ribosomal DNA in eight horticulturally important species of Cymbidium (Orchidaceae) from north-east India (South-East Asia) has been carried for the first time. Observations revealed only one pair of chromosomes had NOR loci. Three, out of eight Cymbidiums showed decondensed, dispersed, extended form of hybridization signals of rDNA as dots of fluorescence (transcriptionally active), where as the rest of the Cymbidiums revealed condensed (non-active) forms, hence demonstrated the heteromorphism in size, intensities and their appurtenance which may be under epigenetic control. Except for the ribosomal genes, no other active genes have been reported to reside within the nucleoli. Such observations provide useful chromosome landmarks and provide valuable evidence about the genome evolution, speciation and ploidy both at molecular and chromosomal levels which is more or less highly ambiguous in family Orchidaceae.
authors.affiliation: Department of Biotechnology and Bioinformatics, North-Eastern Hill University, Shillong (Meghalaya), India.
authors.forename: Santosh Kumar
authors.initials: SK
authors.lastname: Sharma
authors.forename: Poonam
authors.initials: P
authors.lastname: Mehra
authors.forename: Jyoti
authors.initials: J
authors.lastname: Kumari
authors.forename: Sundip
authors.initials: S
authors.lastname: Kumar
authors.forename: Suman
authors.initials: S
authors.lastname: Kumaria
authors.forename: Pramod
authors.initials: P
authors.lastname: Tandon
authors.forename: Satyawada Rama
authors.initials: SR
authors.lastname: Rao
mesh_terms: D017343:Genes, Plant; D020459:Genes, rRNA; D017404:In Situ Hybridization, Fluorescence; D007194:India; D029595:Orchidaceae / Q000235:genetics*; D012335:RNA, Ribosomal / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D012335:RNA, Ribosomal; C088179:RNA, ribosomal, 45S