Biology subjects

Cabral-de-Mello, D. C.

Publications and source records attributed to Cabral-de-Mello, D. C..

3 recordsLinked to original sources

bioRxiv2025

Advancing the understanding of the Bombyx mori genome through satellite DNA analysis: low strain differentiation and relationship with transposable elements

Despite the economic and scientific importance of Bombyx mori, its satellite DNA (satDNA) fraction remains poorly characterized. Here, we present the first comprehensive analysis of the B. mori satellitome, revealing its low abundance ([~]0.76%), A+T enrichment, high monomer size variability, and predominantly dispersed chromosomal organization. Comparative analysis with B. mandarina, the wild ancestor of B. mori, demonstrated high satDNA conservation in abundance and sequence composition, despite speciation and domestication events. Divergence landscapes of satDNA sequences indicate predominantly ancient amplifications with few recent homogenization events. SatDNA families exhibited low strain differentiation across five B. mori strains, exemplified by the consistent presence and abundance of BmorSat01-575 and BmorSat29-84. The W chromosome was identified as a hotspot for satDNA accumulation, especially BmorSat24-753, which showed female-specific amplification and higher sequence homogeneity, suggesting functional or structural roles in W chromosome evolution. In contrast, the Z chromosome displayed similar satDNA content to autosomes, with two families being exclusive to this chromosome and conserved in both Bombyx species. Remarkably, some of B. mori satDNAs were found to be derived from transposable elements (TEs), supporting the hypothesis of TE-driven satDNA origin via multiple mechanisms, including tandemization of TE fragments. Our findings underscore the dynamic interplay between satDNAs and TEs in shaping genome architecture, the stability of the satellitome through domestication, and the sex chromosome-specific accumulation patterns. These insights lay the groundwork for future studies investigating the functional roles of satDNAs in genome regulation and chromatin dynamics in Lepidoptera.

genomics↗

bioRxiv2024

Chromosomal fusion drives sex chromosome evolution in treehoppers despite long-term X chromosome conservation

Sex chromosomes follow distinct evolutionary trajectories compared to the rest of the genome. In many cases, sex chromosomes (X and Y, or Z and W) significantly differentiate from one another resulting in heteromorphic sex chromosome systems. Such heteromorphic systems are thought to act as an evolutionary trap that prevents subsequent turnover of the sex chromosome system. For old, degenerated sex chromosome systems in which turnover is unlikely, chromosomal fusion with an autosome may be one way that sex chromosomes can refresh their sequence content. We investigated these dynamics using treehoppers (hemipteran insects of the family Membracidae), which ancestrally have XX/X0 sex chromosomes. We assembled the first chromosome-level treehopper genome from Umbonia crassicornis and employed comparative genomic analyses of 12 additional treehopper species to analyze X chromosome variation across different evolutionary timescales. We find that the X chromosome is largely conserved, with one exception being an X-autosome fusion in Calloconophora caliginosa. We also compare the ancestral treehopper X with other X chromosomes in Auchenorrhyncha (the clade containing treehoppers, leafhoppers, spittlebugs, cicadas, and planthoppers), revealing X conservation across more than 300 million years. These findings shed light on chromosomal evolution dynamics in treehoppers and the role of chromosomal rearrangements in sex chromosome evolution. SignificanceThe evolutionary forces underlying sex chromosome stability versus turnover have been challenging to disentangle. We present the first chromosome-level treehopper genome and find evidence of long-term X chromosome conservation within treehoppers - and among treehoppers and other hemipteran insects. A key exception is the evolution of neo-XX/XY sex chromosomes via an X-autosome fusion. Sex chromosome-autosome fusions may play an important role in the evolution of otherwise trapped (i.e., old and degenerated) sex chromosome systems.

evolutionary biology↗

bioRxiv2020

Dynamic Sex Chromosome Expression in Drosophila Male Germ Cells

Sex chromosome gene content and expression is unusual. In many organisms the X and Y chromosomes are inactivated in spermatocytes, possibly as a defense mechanism against insertions into unpaired chromatin. In addition to current sex chromosomes, Drosophila has a small gene-poor X-chromosome relic (4th) that re-acquired autosomal status. Using single cell RNA-Seq, we demonstrate that the single X and pair of 4th chromosomes are specifically inactivated in primary spermatocytes. In contrast, genes on the single Y chromosome become maximally active in primary spermatocytes. Reduced X steady-state transcript levels are due to failed activation of RNA-Polymerase-II by phosphorylation of Serine 2 and 5. One Sentence SummarySex chromosome expression during spermatogenesis at the single cell level

developmental biology↗