The 5S rDNA related repetitive sequences in the sex chromosomes of the spiny eel (Mastacembelus aculeatus).
The karyotype of the spiny eel (Mastacembelus aculeatus) has highly evolved heteromorphic sex chromosomes. X and Y chromosomes differ from each other in the distribution of heterochromatin blocks. To characterize the repetitive sequences in these heterochromatic regions, we microdissected the X chromosome, constructed an X chromosome library, amplified the genomic DNA using PCR and isolated a repetitive sequence DNA family by screening the library. All family members were clusters of two simple repetitive monomers, MaSRS1 and MaSRS2. We detected a conserved 5S rDNA gene sequence within monomer MaSRS2; thus, tandem-arranged MaSRS1s and MaSRS2s may co-compose 5S rDNA multigenes and NTSs in M. aculeatus. FISH analysis revealed that MaSRS1 and MaSRS2were the main components of the heterochromatic regions of the X and Y chromosomes. This finding contributes additional data about differentiation of heteromorphic sex chromosomes in lower vertebrates.
College of Life Science, Wuhan University, Wuhan, PR China.
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Zhao
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Zhang
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Zhang
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Chen
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Long
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Liu
D000818:Animals; D001483:Base Sequence; D003582:Cytogenetics; D017931:DNA Primers / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics*; D004524:Eels / Q000235:genetics*; D022041:Euchromatin / Q000235:genetics; D005260:Female; D006570:Heterochromatin / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D012341:RNA, Ribosomal, 5S / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D014960:X Chromosome / Q000235:genetics*; D014998:Y Chromosome / Q000235:genetics*
D017931:DNA Primers; D004275:DNA, Ribosomal; D022041:Euchromatin; D006570:Heterochromatin; D012341:RNA, Ribosomal, 5S