Biology subjects

Ortega-Recalde, O.

Publications and source records attributed to Ortega-Recalde, O..

4 recordsLinked to original sources

bioRxiv2026

Gonadal remodelling in socially driven sex change is associated with novel and known sex genes, epigenetic reprogramming, and inflammation-mediated apoptosis.

Many fish undergo dramatic, socially cued female-to-male sex change, yet the events that initiate and then regulate gonadal reprogramming and reorganisation during this phenomenal metamorphosis are broadly unknown. The New Zealand spotted wrasse, Notolabrus celidotus, is a temperate fish species that displays the extraordinary ability to undergo protogynous sex change. Removal of a terminal-phase male from a social group triggers the most dominant female to change sex and become a male. To characterise the molecular changes associated with gonadal metamorphosis in spotty, we used genomic and transcriptomic approaches, generating a high-quality genome and a transcriptomic time-series that captures the sex change process from start to finish. These data, together with paired histological data, reveal distinct transcriptional profiles that characterise the process of sex change. As expected, the expression of masculinising genes steadily increases, while feminising genes steadily decrease, throughout the transition. We further identify novel candidate genes, including genes involved in immune signalling and tissue remodelling through inflammation-mediated apoptosis, whose expression strongly correlates with key events in sex change, while also confirming the roles of known sex determination and differentiation genes in this process. Collectively these data give us new insights into how a normally committed developmental process remains plastic and is reversed to completely alter organ structures, and also sheds light on the evolution of sex determination in other animals. This work furthers the development of the spotty as a new tractable model for sex change research.

genomics↗

bioRxiv2021

Pronounced sequence specificity of the TET enzyme catalytic domain guides its cellular function

TET (ten-eleven translocation) enzymes catalyze the oxidation of 5-methylcytosine bases in DNA, thus driving active and passive DNA demethylation. Here, we report that the catalytic cores of mammalian TET enzymes favor CpGs embedded within bHLH and bZIP transcription factor binding sites, with 250-fold preference in vitro. Crystal structures and molecular dynamics calculations show that sequence preference is caused by intra-substrate interactions and CpG flanking sequence indirectly affecting enzyme conformation. TET sequence preferences are physiologically relevant as they explain the rates of DNA demethylation in TET-rescue experiments in culture and in vivo within the zygote and germline. Most and least favorable TET motifs represent DNA sites that are bound by methylation-sensitive immediate-early transcription factors and OCT4, respectively, illuminating TET function in transcriptional responses and pluripotency support. One-Sentence SummaryThe catalytic domains of the enzymes that facilitate passive and drive active DNA demethylation have intrinsic sequence preferences that target DNA demethylation to bHLH and bZIP transcription factor binding sites.

molecular biology↗

bioRxiv2020

Paternal hypoxia exposure primes offspring for increased hypoxia resistance

In a time of rapid environmental change, understanding how the challenges experienced by one generation can influence the fitness of future generations is critically needed. Using tolerance assays, transcriptomic and methylome approaches, we use zebrafish as a model to investigate transgenerational acclimation to hypoxia. We show that short-term paternal exposure to hypoxia endows offspring with greater tolerance to acute hypoxia. We detected two hemoglobin genes that are significantly upregulated by more than 7-fold in the offspring of hypoxia exposed males. Moreover, the offspring which maintained equilibrium the longest showed greatest upregulation in hemoglobin expression. We did not detect differential methylation at any of the differentially expressed genes, suggesting that another epigenetic mechanism is responsible for alterations in gene expression. Overall, our findings suggest that a memory of past hypoxia exposure is maintained and that this environmentally induced information is transferred to subsequent generations, pre-acclimating progeny to cope with hypoxic conditions.

evolutionary biology↗

bioRxiv2018

Stress, novel sex genes and epigenetic reprogramming orchestrate socially-controlled sex change

Bluehead wrasses undergo dramatic, socially-cued female to male sex change. We apply transcriptomic and methylome approaches in this wild coral reef fish to identify the primary trigger and subsequent molecular cascade of gonadal metamorphosis. Our data suggest that the environmental stimulus is exerted via the stress axis, that repression of the aromatase gene (encoding the enzyme converting androgens to estrogens) triggers a cascaded collapse of feminizing gene expression, and identifies notable sex-specific gene neofunctionalization. Furthermore, sex change involves distinct epigenetic reprogramming and an intermediate state with altered epigenetic machinery expression akin to the early developmental cells of mammals. These findings reveal at a molecular level how a normally committed developmental process remains plastic and is reversed to completely alter organ structures.\n\nOne Sentence SummaryOvary to testis transformation in a sex-changing fish involves transcriptomic and epigenomic reprogramming.

molecular biology↗