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Uliano da Silva, M.

Publications and source records attributed to Uliano da Silva, M..

3 recordsLinked to original sources

An atlas of eukaryotic centromere architecture reveals recurrent evolutionary dynamics

Centromeres evolved at the root of eukaryotes to segregate chromosomes during cell division. Despite their ancient origin, centromeric DNA sequences evolve rapidly and adopt diverse architectures, including point centromeres, satellite arrays, transposon clusters, and holocentrics. To analyse centromere evolution at a broad scale, we characterised architectures across 325 diverse Darwin Tree of Life genome assemblies. Centromere architecture is evolutionarily labile, and similar configurations arise independently across divergent lineages. In plants and animals, we modelled centromere evolution as a recurrent cycle, in which satellite- and transposon-based architectures interconvert, with independent origins of holocentricity. We curated >23 million satellite repeats comprising 263 families from 165 species. Despite sequence divergence between satellite families, higher order repeats are prevalent, indicating constraint on repeat architecture rather than primary sequence. Satellite arrays are heavily invaded by diverse transposon families, consistent with convergent adaptation to the centromeric niche. In 89 species, transposons themselves constitute the primary centromere structure. We observed centrophilic transposons forming tandem arrays, suggesting mechanisms for satellite regeneration. Our sample includes five independent origins of holocentricity in plants and animals, which vary in association with periodic satellite arrays. We propose that genetic instability, centrophilic transposition, and transmission distortion promote recurrent centromere architectural interconversions during evolution.

genomics↗

The globally dispersed sun-coral species is _Tubastraea coccinea_ (Cnidaria: Anthozoa)

Species of the genus Tubastraea (sun corals) have dispersed globally over recent decades, but morphological trait identification has led to taxonomic confusion, with multiple authors proposing conflicting species identifications due to high morphological plasticity and overlapping diagnostic traits. We combined global-scale molecular phylogenetics with chromosome-level genome assemblies to resolve this taxonomic issue. Using mitochondrial and nuclear markers from 287 specimens across five ocean regions, including type localities in Bora Bora (T. coccinea) and Galapagos (T. tagusensis), we reconstructed phylogenetic relationships and inferred demographic history through approximate Bayesian computation. We also generated high-quality, chromosome-level genome assemblies for three morphologically distinct morphotypes from the Brazilian coastline. Phylogenetic and species delimitation analyses revealed two well-supported clades: a small, geographically restricted T. tagusensis clade confined to the Galapagos Islands, and a large cosmopolitan clade containing all worldwide samples, including T. coccinea from its type locality. Chromosome-level genomic analyses confirmed that the three morpho-types represent a single species, sharing a triploid karyotype of 14 chromosomes with extensive synteny and gene-tree discordance consistent with incomplete lineage sorting. Dispersed-route analyses identified the Centralwestern Pacific as the ancestral source, with at least three independent, humanmediated colonization events establishing populations in the Southwestern Atlantic, Gulf of Mexico, and Western Pacific. However, preliminary analysis suggests a Galapagos (Southeastern Pacific) origin rather than Centralwestern Pacific for the T. tagusensis and T. coccinea cluster. Our results definitively establish Tubastraea coccinea as the cosmopolitan species responsible for global dissemination, while T. tagusensis is endemic to the Galapagos and not involved in the worldwide dis-persion.

genetics↗

De novo assembly and characterization of a highly degenerated ZW sex chromosome in the fish Megaleporinus macrocephalus

BackgroundMegaleporinus macrocephalus (piaucu) is a Neotropical fish within Characoidei that presents a well-established heteromorphic ZZ/ZW sex-determination system and thus, constitutes a good model for studying W and Z chromosomes in fishes. We used PacBio reads and Hi-C to assemble a chromosome-level reference genome for M. macrocephalus. We generated family segregation information to construct a genetic map, pool-seq of males and females to characterize its sex system, and RNA-seq to highlight candidate genes of M. macrocephalus sex determination. ResultsM. macrocephalus reference genome is 1,282,030,339 bp in length and has a contig and scaffold N50 of 5.0 Mb and 45.03 Mb, respectively. Based on patterns of recombination suppression, coverage, Fst, and sex-specific SNPs, three major regions were distinguished in the sex chromosome: W-specific (highly differentiated), Z-specific (in degeneration), and PAR. The sex chromosome gene repertoire was composed of genes from the TGF-{beta} family (amhr2, bmp7) and Wnt/{beta}-catenin pathway (wnt4, wnt7a), and some of them were differentially expressed. ConclusionsThe chromosome-level genome of piaucu exhibits high quality, establishing a valuable resource for advancing research within the group. Our discoveries offer insights into the evolutionary dynamics of Z and W sex chromosomes in fish, emphasizing ongoing degenerative processes and indicating complex interactions between Z and W sequences in specific genomic regions. Notably, amhr2 and bmp7 are potential candidate genes for sex determination in M. macrocephalus.

genomics↗