RESUMO
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RESUMO
The genus Saimiri is a decades-long taxonomic and phylogenetic puzzle to which cytogenetics has contributed crucial data. All Saimiri species apparently have a diploid number of 2n = 44 but vary in the number of chromosome arms. Repetitive sequences such as satellite DNAs are potentially informative cytogenetic markers because they display high evolutionary rates. Our goal is to increase the pertinent karyological data by more fully characterizing satellite DNA sequences in the Saimiri genus. We were able to identify two abundant satellite DNAs, alpha (~340 bp) and CapA (~1,500 bp), from short-read clustering of sequencing datasets from S. boliviensis. The alpha sequences comprise about 1% and the CapA 2.2% of the S. boliviensis genome. We also mapped both satellite DNAs in S. boliviensis, S. sciureus, S. vanzolinii, and S. ustus. The alpha has high interspecific repeat homogeneity and was mapped to the centromeres of all analyzed species. CapA is associated with non-pericentromeric heterochromatin and its distribution varies among Saimiri species. We conclude that CapA genomic distribution and its pervasiveness across Platyrrhini makes it an attractive cytogenetic marker for Saimiri and other New World monkeys.
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Satellite DNAs (satDNAs) constitute large portion of eukaryote genomes, comprising non-protein-coding sequences tandemly repeated. They are mostly found in heterochromatic regions of chromosomes such as around centromere or near telomeres, in intercalary heterochromatin, and often in non-recombining segments of sex chromosomes. We examined the satellitome in the cricket Eneoptera surinamensis (2n = 9, neo-X1X2Y, males) to characterize the molecular evolution of its neo-sex chromosomes. To achieve this, we analyzed illumina reads using graph-based clustering and complementary analyses. We found an unusually high number of 45 families of satDNAs, ranging from 4 bp to 517 bp, accounting for about 14% of the genome and showing different modular structures and high diversity of arrays. FISH mapping revealed that satDNAs are located mostly in C-positive pericentromeric regions of the chromosomes. SatDNAs enrichment was also observed in the neo-sex chromosomes in comparison to autosomes. Especially astonishing accumulation of satDNAs loci was found in the highly differentiated neo-Y, including 39 satDNAs over-represented in this chromosome, which is the greatest satDNAs diversity yet reported for sex chromosomes. Our results suggest possible involvement of satDNAs in genome increasing and in molecular differentiation of the neo-sex chromosomes in this species, contributing to the understanding of sex chromosome composition and evolution in Orthoptera.
Assuntos
Cromossomos de Insetos , DNA Satélite , Gryllidae/genética , Cromossomo Y , Animais , Mapeamento Cromossômico , Feminino , Genoma de Inseto , Sequenciamento de Nucleotídeos em Larga Escala , Hibridização in Situ Fluorescente , MasculinoRESUMO
This study analyzed sequences of the control region of mitochondrial DNA (D-loop) in three populations of Parauchenipterus galeatus from the basins of the Paraná, São Francisco, and Piumhi rivers, of which the last river being a region that suffered transposition river. A fragment of 850 base pairs was obtained with a total of 65 polymorphic sites. The data discuss aspects related to the genetic distance between the populations through the phylogenetic reconstruction methods (neighbor-joining, maximum-likelihood, and Bayesian analysis). Moreover, the data suggest that the Piumhi River population (transposition region) has recently gone through a significant bottleneck effect, which must be directly related to the anthropic action that occurred in this region, since the drainage the old existing swamp was necessary for the construction of the transposition channel potentially leading this population in to the current lack of genetic diversity.