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Variation in size and location of the Ag-NOR in the Atlantic halibut (Hippoglossus hippoglossus)

Citation
Ocalewicz K, Penman D & Babiak I (2008) Variation in size and location of the Ag-NOR in the Atlantic halibut (Hippoglossus hippoglossus), Genetica, 133 (3), pp. 261-267.

Abstract
The distribution of differentially stained chromatin was studied in the Atlantic halibut (Hippoglossus hippoglossus) chromosomes (2n = 48). Four pairs of homologous chromosomes were identified using a combination of traditional cytogenetic staining techniques (Giemsa/DAPI/CMA3/Ag-NO3). Chromosome 1 showed a length polymorphism (1(S)-short, 1(L)-long isoforms of the chromosome 1) which was related to the variation of the size of the Ag-NORs. In one specimen the Ag-NOR was translocated from chromosome 1 into the telomeric region on the q-arm of the chromosome 2 forming a derivative chromosome der(2)t(1(S);2)(q?;q?). Four Ag-NOR genotypes have been shown: 1(S)1(S), 1(S)1(L), 1(L)1(L) and 1(S) der(2)t (1(S);2)(q?;q?). The chromosome rearrangements did not leave any interstitially located telomeric sequences and the telomeres were confined to the ends of the chromosomes. A single chromosomal location of 5S rDNA clusters was found using the PRINS technique. In the extended metaphase spreads two adjacent clusters of 5S rDNA could be seen on one chromosome while condensed chromatin gave a single hybridization signal. Double 5S rDNA signals on the same chromosome arm suggested paracentric inversion of the minor rDNA site. 5S rDNA clusters were not co-localized with Ag-NORs. Although female and male karyotypes were compared no sex related cytogenetic markers were found.

Keywords
Chromosomes; DAPI; NORs; Polymorphism; Atlantic halibut; Sex

StatusPublished
AuthorsOcalewicz Konrad, Penman David, Babiak Igor
Publication date07/2008
Publication date online09/2007
PublisherSpringer
Place of publicationDORDRECHT, NETHERLANDS
ISSN 0016-6707
LanguageEnglish

Journal
Genetica: Volume 133, Issue 3 (2008/07//)

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