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Title: GC- rich heterochromatin in silver stained nucleolar organizer regions (NORs) fluoresces with Chromomycin A<sub>3</sub> (CMA<sub>3</sub>) staining in three species of teleostean fishes (Pisces)
Authors: Das, Jayanta Kumar
Khuda-Bukhsh, Anisur Rahman
Keywords: Ag-NOR
Chromomycin A<sub>3</sub> banding
Chromomycin A<sub>3</sub> banding
G-C rich region
<i style="">Hemibagrus menoda</i>
<i style="">Mastacembelus armatus</i>
<i style="">Sperata seenghala</i>
Issue Date: May-2007
Publisher: CSIR
Abstract: In a bid to ascertain the molecular architecture of the silver positive regions (NORs) in chromosomes of three species of fish, namely, <i style="">Hemibagrus menoda</i> (Hamilton), <i style="">Sperata seenghala</i> (Sykes) (Fam: Bagridae) and <i style="">Mastacembelus armatus</i> (Lacep├Ęde) (Fam: Mastacembelidae), an additional staining methodology using a fluorochrome dye (Chromomycin A<sub>3</sub>)<sub> </sub>was deployed along with the AgNO<sub>3 </sub>technique. The nucleolar organizing regions (NORs) were located terminally at the shorter arms (Tp) of one pair of submetacentric chromosomes (No.3) in <i style="">H. menoda </i>(2n=58), at the longer arms (Tq) of one pair of submetacentric chromosomes (No.5) in <i style="">S. seenghala </i>(2n<i style="">=</i>50) and at the shorter arm (Tp) of one pair of homologous submetacentric chromosomes (No.6) in <i style="">M. armatus</i> (2n=48). Staining with Chromomycin A<sub>3</sub> produced bright fluorescing zones in GC- rich heterochromatin of Ag-positive NORs. The results indicate a more general trend of existence of an overlapping region between NOR and GC- rich fluorescing zones, the active sites of rRNA genes (rDNA) in this primitive group of vertebrates although exceptions to this situation has been reported in a couple of extant fish species earlier. More data utilizing such combined methodologies are warranted to understand the structural organization of fish chromosomes more precisely.
Description: 413-418
ISSN: 0975-1009 (Online); 0019-5189 (Print)
Appears in Collections:IJEB Vol.45(05) [May 2007]

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