Biology subjects

Olivier, L.

Publications and source records attributed to Olivier, L..

4 recordsLinked to original sources

bioRxiv2026

Epigenetic Resilience to Early-Life Maternal Loss in African Savanna Elephants

Early-life trauma in humans, including maternal loss, is strongly associated with increased risk of chronic diseases, reduced life expectancy, and accelerated biological aging, as measured through epigenetic modifications, such as DNA methylation. Whether similar patterns occur in other long-lived, socially complex non-primate species, however, remains unknown. Elephants share key life-history traits with humans, including longevity, strong social bonds, and advanced cognitive abilities. Yet wild elephant populations face significant anthropogenic and environmental pressures, including poaching, habitat loss, and human-wildlife conflict that can result in maternal mortality and subsequent calf orphaning. We examined whether orphaning of elephant calves was associated with accelerated DNA methylation age and distinct epigenetic signatures. Contrary to our hypothesis and patterns observed in other species, orphaned African savanna elephants exhibited a younger DNA methylation age than non-orphans, no accelerated aging, and only limited differential methylation at CpG sites. At the genome-wide level, chronological age was not associated with differential CpG methylation after correcting for multiple testing. One interpretation of these findings is that elephants may have evolved mechanisms that buffer against epigenetic instability following stressful events. Investigating these protective mechanisms in elephants could inform strategies to mitigate the long-term health impacts of early-life trauma in humans. Significance StatementIn most mammals, early-life adversity, including maternal loss is associated with shorter lifespans and widespread epigenetic alterations. In contrast, we found that orphaned African savanna elephants exhibited a younger epigenetic age compared to non-orphans and showed only a weak distinct epigenetic signature. This unexpected pattern may reflect environmental influences, such as living under human care, or evolutionary adaptations that buffer against epigenetic instability. If the latter is confirmed, such mechanisms could confer resilience to the epigenetic consequences of early-life adversity.

genomics↗

bioRxiv2026

UbiB proteins mediate an ATP-dependent decarboxylation step in bacterial ubiquinone biosynthesis

Polyisoprenoid quinones such as ubiquinone (UQ) play an essential role in cellular physiology, acting as membrane-bound electron and proton carriers in respiratory chains and other biological processes across all domains of life. In Escherichia coli, the canonical UQ biosynthesis pathway is well characterized. It involves twelve proteins (UbiA-UbiK and UbiX), most of which catalyzing one of the eight modifications of the aromatic ring derived from 4-hydroxybenzoic acid (4-HB), while others (UbiB, UbiJ, UbiK) act as accessory factors ensuring efficient UQ production. Following prenylation by UbiA and subsequent decarboxylation by the UbiX/UbiD system, the final six reactions are catalyzed within a soluble Ubi-complex. UbiB, an atypical protein kinase-like enzyme, was proposed to extract decarboxylated intermediates from the membrane and mediate their delivery to the Ubi-complex. In this study, we demonstrate the existence of an alternative decarboxylation system in E. coli, as UQ biosynthesis can proceed in the absence of the UbiX/UbiD system. Our results show that this alternative decarboxylation activity depends on UbiB and requires its ATPase activity. Bioinformatic analyses further revealed that approximately 27% of Pseudomonadota species lack UbiX/UbiD homologs, and we found that UbiB proteins from two such species enhance the alternative decarboxylation activity when expressed in E. coli. In addition, we identified conserved residues in UbiB that are specifically required for decarboxylation but dispensable for the delivery of UQ intermediates to the Ubi-complex. Taken together, our findings support a model in which UbiB acts as an ATP-dependent decarboxylase, thereby broadening the functional scope of this poorly characterized protein. ImportancePolyisoprenoid quinones, including ubiquinone (UQ, also known as coenzyme Q), are essential electron and proton carriers in respiratory chains across all domains of life. After prenylation and decarboxylation, the final six steps of UQ biosynthesis are carried out by a soluble Ubi-complex. The only decarboxylation system currently identified in the UQ pathway, the UbiX/UbiD system, is absent from numerous bacterial genomes, and no isofunctional enzymes have been described to date. UbiB, an atypical protein kinase-like enzyme, has been proposed to mediate the extraction of UQ precursors from the membrane, thereby rendering them accessible to the soluble Ubi-complex. Here, we show that UbiB proteins fulfill an additional function in bacteria. Specifically, they contribute to the decarboxylation of UQ precursors through a mechanism that remains unknown but depends on ATP hydrolysis. Given that UbiB is conserved in all UQ-producing bacteria, it may represent a widespread decarboxylation system within this essential metabolic pathway.

biochemistry↗

bioRxiv2023

Species-level identification of the critically endangered European sturgeon Acipencer sturio using DNA-based approaches.

The native European sturgeon Acipenser sturio is the focus of restoration programs. However, A. sturio identification by direct observation is not always obvious for non-specialists. We aimed to develop a quick and easy genetic tool applicable to identify the species at risk in case of incidental capture or monitoring either at sea or in the watershed. We showed that primers and probe developed allow specific amplification for A. sturio by PCR, qPCR and Real-Time Loop-mediated isothermal amplification (LAMP) techniques. We determine benefits and limits of each method and highlight perspectives for field applications within the frame of conservation programs.

ecology↗

bioRxiv2021

Interspecific gene flow and vicariance in Northern African rear-edge white oak populations revealed by joint analysis of microsatellites and flanking sequences.

Inference of recent population divergence requires fast evolving markers and necessitates to differentiate shared genetic variation caused by ancestral polymorphism and gene flow. Theoretical research shows that the use of compound marker systems integrating linked polymorphisms with different mutational dynamics, such as a microsatellite and its flanking sequences, can improve estimation of population structure and inference of demographic history, especially in the case of complex population dynamics. However, empirical application in natural populations has so far been limited by lack of suitable methods for data collection. A solution comes from the development of sequence-based microsatellite genotyping which we used to study molecular variation at 36 sequenced nuclear microsatellites in seven Quecus canariensis and four Quercus faginea rear-edge populations across Algeria, to decipher their taxonomic relationship, past evolutionary history and recent demographic trajectory. First, we compare the estimation of population genetics parameters and simulation-based inference of demographic history from microsatellite sequence alone, flanking sequence alone or the combination of linked microsatellite and flanking sequence variation. Second, we measure variable importance from random forest approximate Bayesian computation to identify which of these sequence types is most informative. Whereas the analysis of microsatellite variation alone indicates recent interspecific gene flow, additional information gained from combining with nucleotide variation in flanking sequences, by reducing homoplasy, suggests ancient interspecific gene flow followed by drift in isolation instead. The weight of each polymorphism in the inference also demonstrates the value of linked variations with contrasted mutation dynamic to improve estimation of both demographic and mutational parameters.

evolutionary biology↗