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Molecular Biology Reports

, Volume 40, Issue 1, pp 723–729 | Cite as

Chromosome breakages associated with 45S ribosomal DNA sequences in spotted snakehead fish Channa punctatus

  • Mamta Singh
  • Anindya Sundar Barman
Article

Abstract

It is well known that transcriptionally inactive rRNA genes are correlated with DNA hyper-methylation and histone hypo-methylation and there is clear evidence in humans that DNA and histone modification which alter chromatin structure are related to chromosome fragility. Very little is known about the biological cause of 45S rDNA fragility. In this report we characterized the chromosome breakage or gap associated with 45S rDNA in a fish species Channa punctatus. The rDNA mapping in C. punctatus, showed many chromosome breakages or gap formations, and all occurred exclusively in the 45S rDNA sites in anterior kidney cells. We observed that the number of chromosomes plus chromosome fragments was often more than the expected 32 in most cells. Total 67 % metaphase spread showed the expected or normal 32 chromosomes, while 33 % metaphase spread showed 33 and/or 34 chromosomes and/or chromosome fragments. The chromosome lesions observed in this study are very similar cytologically to that of fragile sites observed in human chromosomes. Possible causes for the spontaneous expression of fragile sites and their potential biological significance are also discussed in present report.

Keywords

rDNA Chromosome fragile site Gap Channa punctatus 

Supplementary material

11033_2012_2112_MOESM1_ESM.pdf (76 kb)
Supplementary material 1 (PDF 75 kb)
11033_2012_2112_MOESM2_ESM.pdf (78 kb)
Supplementary material 2 (PDF 77 kb)

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Copyright information

© Springer Science+Business Media Dordrecht 2012

Authors and Affiliations

  1. 1.Department of Fish Genetics and ReproductionCollege of Fisheries (Central Agriculture University) LembucherraTripura (W)India

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