Biology subjects

Vernet, P.

Publications and source records attributed to Vernet, P..

4 recordsLinked to original sources

bioRxiv2026

The structure and evolution of sex chromosomes in an androdioecious species with two mating types.

Though flowering plants are ancestrally hermaphroditic, some species have evolved sexual specialization and are now composed of individuals expressing just one of their two reproductive functions (either male or female) together with co-sexual individuals. Androdioecy, the co-existence of males with hermaphrodites, is rare across the living world, but unusually common in species of the Oleaceae plant family. The mediterranean shrub Phillyrea angustifolia has a simple mendelian XY sex-determination system for androdioecy, but the underlying molecular determinants and the evolutionary history of the X and Y chromosomes remain unknown. The ability of males to by-pass the self-incompatibility phenotype expressed in hermaphrodites is essential to explain their high frequency in natural populations, but how the loci governing sex and self-incompatibility epistatically interact also remains unknown. To address these questions, we obtained full haplotype-resolved de novo chromosomal assemblies of P. angustifolia and its sister species P. latifolia. The sex-determining region in P. angustifolia spanned a fifth of chromosome 12, and was strikingly larger and more rearranged than that in P. latifolia. The male-specific region contains two putative sex-determining genes, ANDY1 and ANDY2, a tandem encoding two flowering-related transcription factors that arose by translocation followed by duplication of an autosomal gene before the two species diverged. Strikingly, this sex-determining region also contains a recent duplicate of the pollen allergen gene Ole-e1, which shows the strongest differential expression between the two self-incompatibility groups of hermaphrodites, hence establishing a direct molecular link between sex and self-incompatibility. Overall, our results provide novel insight on sex determination and the evolution of sex chromosomes in a plant lineage where the separation between sexes is still incomplete, and offer a possible mechanistic basis for the strong epistatic interaction between the sex and self-incompatibility determinants, with direct implication for how sex-ratios are established in nature.

evolutionary biology↗

bioRxiv2025

Cellular and mitochondrial effects of a gold-N Heterocyclic Carbene on LNCaP and PC3 prostate cancer cell lines

The discovery of cisplatin and its anti-tumor activities but also its side-effects led to the development of new cytotoxic metal complexes. Metal-based compounds and especially gold N-heterocyclic carbene complexes have shown their antitumoral activities and present a great interest of use in medicine. These metallodrugs have been shown to target nuclear DNA, but also other organelles such as mitochondria. The mechanisms of action have been studied and would involve the triggering of cell death, in particular by apoptosis, highlighting mitochondrial dysfunctions. The organometallic compound used in this study has been characterized by its IC50 and GI50 in two prostatic cancer cell lines (LNCaP and PC3). Its capacity to enter the cells and particularly mitochondria was also analyzed. Furthermore, its effects on several parameters (proliferation, cell death, cell cycle) have been determined in vitro. The compound displayed a cytotoxic effect (IC50 < 5{micro}M) confirmed by the MTT assays and cell death analysis by flow cytometry. It also displayed a cytostatic effect confirmed by the determination of the GI50, and induced a brief cell cycle arrest, depending on the cell line and the metallocarbene concentration. Furthermore, the incubation with the gold N-heterocyclic carbene led to mitochondrial membrane potential changes and decreased the accumulation of the mitochondrial protein Rieske. All our results show a global cytotoxic and cytostatic effects of the gold N-heterocyclic carbene that can involve mitochondria.

pharmacology and toxicology↗

bioRxiv2021

Genetic mapping of sex and self-incompatibility determinants in the androdioecious plant Phillyrea angustifolia

AO_SCPLOWBSTRACTC_SCPLOWThe diversity of mating and sexual systems in angiosperms is spectacular, but the factors driving their evolution remain poorly understood. In plants of the Oleaceae family, an unusual self-incompatibility (SI) system has been discovered recently, whereby only two distinct homomorphic SI specificities segregate stably. To understand the role of this peculiar SI system in preventing or promoting the diversity of sexual phenotypes observed across the family, an essential first step is to characterize the genetic architecture of these two traits. Here, we developed a high-density genetic map of the androdioecious shrub P. angustifolia based on a F1 cross between a hermaphrodite and a male parent with distinct SI genotypes. Using a double restriction-site associated digestion (ddRAD) sequencing approach, we obtained reliable genotypes for 196 offspring and their two parents at 10,388 markers. The resulting map comprises 23 linkage groups totaling 1,855.13 cM on the sex-averaged map. We found strong signals of association for the sex and SI phenotypes, that were each associated with a unique set of markers on linkage group 12 and 18 respectively, demonstrating inheritance of these traits as single, independent, mendelian factors. The P. angustifolia linkage map shows robust synteny to the olive tree genome overall. Two of the six markers strictly associated with SI in P. angustifolia have strong similarity with a recently identified 741kb chromosomal region fully linked to the SI phenotype on chromosome 18 of the olive tree genome, providing strong cross-validation support. The SI locus stands out as being markedly rearranged, while the sex locus has remained relatively more collinear between the two species. This P. angustifolia linkage map will be a useful resource to investigate the various ways by which the sex and SI determination systems have co-evolved in the broader phylogenetic context of the Oleaceae family.

evolutionary biology↗

bioRxiv2020

Widespread coexistence of self-compatible and self-incompatible phenotypes in a diallelic self-incompatibility system in Ligustrum vulgare (Oleaceae)

The breakdown of self-incompatibility (SI) in angiosperms is one of the most commonly observed evolutionary transitions. While multiple examples of SI breakdown have been documented in natural populations, there is strikingly little evidence of stable within-population polymorphism with both inbreeding (self-compatible) and outcrossing (self-incompatible) individuals. This absence of mating system polymorphism corroborates theoretical expectations that predict that in/outbreeding polymorphism is possible only under very restricted conditions. However, theory also predicts that a diallelic sporophytic SI system facilitates the maintenance of such polymorphism. We tested this prediction by studying the mating system of Ligustrum vulgare L., an entomophilous hermaphroditic species of the Oleaceae family. Using stigma tests with controlled pollination and paternity assignment of open-pollinated progenies, we confirmed the existence of two self-incompatibility groups in this species. We also demonstrated the existence of self-compatible individuals in different populations of Western Europe arising from a mutation affecting the expression of the pollen component of SI. We then estimated the selfing rate in a garden experiment. Our results finally show that the observed low frequency of self-compatible individuals in natural populations is compatible with theoretical predictions only if inbreeding depression is very high.

evolutionary biology↗