Conservação e eliminação de DNAs satélites: a diferenciação do cromossomo W em Triportheus (Teleostei: Characiformes)
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Date
2023-08-18Author
Oliveira, Mariannah Pravatti Barcellos
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The evolution of sex chromosomes raises several issues that have yet to be
resolved, like why are repeated sequences often species-specific on sex
chromosomes prone to accumulating? To better explore this, this work aims to
trace the dynamics of satellite DNAs (satDNAs) accumulation and elimination
along the pathway of W chromosome differentiation using the well-known
Triportheus fish model. This fish genus stands out due to a conserved ZZ/ZW
sex chromosome system present in all examined species. While the Z
chromosome is conserved in all species, the W chromosome is smaller and
exhibits differences in size and morphology. The presumed ancestral W
chromosome is comparable to that of Triportheus auritus and contains 19
different SatDNA families accumulating on it. The results found in the analysis
of five additional Triportheus species showed that most of these repetitions
were probably eliminated as speciation was taking place and the W
chromosomes continued their path of differentiation, while the Z chromosomes
of some species began to accumulate some TauSatDNAs. Additional
species-specific SatDNAs that made up the heterochromatic region of each of
these chromosomes were most likely amplified after that. Therefore, the W
chromosomes of the various Triportheus species have undergone significant
evolutionary changes in a short period of time (15–25 Myr) after their
divergence.
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