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Human gamma X satellite DNA: an X chromosome specific centromeric DNA sequence
1Department of Laboratory Medicine and Pathology, University of Alberta and the University of Alberta Hospitals, Edmonton, Alberta, Canada, T6G 2B7.
Chromosoma
|November 1, 1995
Summary
Researchers identified a novel repetitive DNA sequence, gamma X satellite DNA, on the human X chromosome. This sequence, found in the centromeric region, shows similarity to gamma 8 satellite DNA and may contain inversions.
Area of Science:
- Molecular Biology
- Genetics
- Human Chromosome Research
Background:
- The cosmid clone CX16-2D12, located in the human X chromosome's centromeric region, lacks typical alpha satellite DNA.
- A specific fragment, 2D12/E2, was isolated and characterized from this cosmid.
Purpose of the Study:
- To analyze the structure and characteristics of the 2D12/E2 DNA fragment.
- To determine the relationship of this sequence to known satellite DNA families.
- To investigate its genomic distribution and potential variations within the human population.
Main Methods:
- DNA sequencing of the 1,205 bp fragment (2D12/E2) to identify repetitive monomer units.
- Sequence homology analysis comparing 2D12/E2 monomers and known satellite DNA sequences (gamma 8).
- Slot-blot hybridization to estimate genomic abundance.
- Pulsed-field gel electrophoresis to assess restriction fragment length polymorphisms.
- Fluorescence in situ hybridization (FISH) for chromosomal localization.
Main Results:
- The 2D12/E2 fragment contains approximately five tandemly repeated 220 bp monomers with 72.8–78.6% internal homology.
- Sequence analysis revealed a potential inversion within the repetitive array and ~62% similarity to gamma 8 satellite DNA consensus.
- A conserved 20 bp sequence was identified between 2D12/E2 and gamma 8 consensus sequences.
- The repetitive DNA constitutes ~0.015% of the human genome, with no observed restriction fragment length polymorphisms in tested individuals.
- FISH confirmed the localization of 2D12/E2 to the lateral sides of the primary constriction on the human X chromosome.
Conclusions:
- The characterized DNA sequence is designated gamma X satellite DNA, suggesting it belongs to a gamma satellite DNA subfamily.
- The presence of inversions in the repetitive array provides insights into centromeric DNA dynamics on the X chromosome.
- Gamma X satellite DNA is a conserved repetitive element on the human X chromosome, with potential implications for centromere structure and function.