Centromeres exhibit highly complex organization and are often flanked by satellite DNA (stDNA) related to their functional maintenance which includes cell division. Here, four novel centromeric stDNA families (MALREP-A, MALREP-B, MALREP-C and MALREP-D) were isolated from genomic DNA of the Asian swamp eel (Monopterus albus, 2n=24), considered to be the lowest chromosome number known in teleosts (2n=42–48), by construction of a genomic fosmid DNA library, characterized by in silico, fluorescence in situ hybridization (FISH) mapping, and filter hybridization. Respective lengths and GC contents of the sequences were 233 bp and 54.3% for MALREP-A, 233 bp and 53.2% for MALREP-B, 293 bp and 52.9% for MALREP-C, and 293 bp and 52.2% for MALREP-D. Principle component analysis showed the existence of several subfamilies in each stDNA family, suggesting large stDNA diversity in centromeric region. Three centromeric stDNA families (MALREP-A, B and D) were located on all chromosomes with different FISH signal intensities, except for MALREP-C localized to 11 pairs, suggesting that centromeric stDNA were separately homogenized among chromosomes. These stDNA families only hybridized with genomic DNA of Asian swamp eel, but no signal was observed even for other teleosts and vertebrates. Similar results, based on in silico mapping, were recorded for whole genome sequences of several vertebrates, suggesting that these stDNA sequences were differentiated rapidly or specifically amplified in the Asian swamp eel genome. Sequences homologous to all families of repeated sequences were searched in Repbase. Most stDNA families showed partial homology with GYPSY and MuDR retrotransposons. This suggests that these centromeric stDNAs were derived from retrotransposons which acted as multifunctional modular elements and essentially shared propagation mechanisms and synergy to shape the genome
Centromeres exhibit highly complex organization and are often flanked by satellite DNA (stDNA) related to their functional maintenance which includes cell division. Here, four novel centromeric stDNA families (MALREP-A, MALREP-B, MALREP-C and MALREP-D) were isolated from genomic DNA of the Asian swamp eel (Monopterus albus, 2n=24), considered to be the lowest chromosome number known in teleosts (2n=42–48), by construction of a genomic fosmid DNA library, characterized by in silico, fluorescence in situ hybridization (FISH) mapping, and filter hybridization. Respective lengths and GC contents of the sequences were 233 bp and 54.3% for MALREP-A, 233 bp and 53.2% for MALREP-B, 293 bp and 52.9% for MALREP-C, and 293 bp and 52.2% for MALREP-D. Principle component analysis showed the existence of several subfamilies in each stDNA family, suggesting large stDNA diversity in centromeric region. Three centromeric stDNA families (MALREP-A, B and D) were located on all chromosomes with different FISH signal intensities, except for MALREP-C localized to 11 pairs, suggesting that centromeric stDNA were separately homogenized among chromosomes. These stDNA families only hybridized with genomic DNA of Asian swamp eel, but no signal was observed even for other teleosts and vertebrates. Similar results, based on in silico mapping, were recorded for whole genome sequences of several vertebrates, suggesting that these stDNA sequences were differentiated rapidly or specifically amplified in the Asian swamp eel genome. Sequences homologous to all families of repeated sequences were searched in Repbase. Most stDNA families showed partial homology with GYPSY and MuDR retrotransposons. This suggests that these centromeric stDNAs were derived from retrotransposons which acted as multifunct ...
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