Biology subjects

Hoareau, M.

Publications and source records attributed to Hoareau, M..

4 recordsLinked to original sources

bioRxiv2024

Transcriptomic bases of within- and trans-generational predator-induced plasticity in the freshwater snail Physa acuta

Inducible defences in response to predation risk are a well-known example of adaptive phenotypic plasticity. Although inducible defences have been studied mainly within a generation (within-generational plasticity), there is now clear evidence that ancestral exposure to predation risk can influence the defences expressed by offspring, even if they have not been exposed themselves (transgenerational plasticity). The molecular mechanisms allowing the transmission of environmental information across generations are not well understood. In this study, we combined measures of antipredator responses (behavioural and morphological) with transcriptomic investigations across two generations in the freshwater snail Physa acuta. We hypothesised that both within- and transgenerational plasticity would induce phenotypic changes associated with differential gene expression. Our results confirmed within- and transgenerational plasticity: F1 snails respond to predator-cue exposure by increasing escape behaviour, reducing shell length, and developing thicker and slenderer shells, whereas F2 snails from exposed parents have longer and thicker shells with narrower apertures. Within- and transgenerational plasticity were accompanied by the differential expression of 112 genes (101 up- and 11 downregulated) and 23 differentially expressed genes (17 up- and 6 downregulated), respectively. Within- and transgenerational plasticity did not share common differentially expressed genes, but the associated molecular functions, involving metabolism and transcription regulation, were similar. These results suggest that predator-induced within-generational plasticity and transgenerational plasticity may result from different genomic pathways and may evolve independently.

evolutionary biology↗

bioRxiv2024

Mind the polar sun: Solar radiations trigger frequent heat stress in breeding king penguins, despite relatively cool air temperatures.

Polar and sub-polar animals evolved to thrive in cold climates and may thus be particularly sensitive to rising temperatures associated with climate change. Penguins may be especially vulnerable, due to their dual habitat, alternating between foraging in cold waters and breeding/moulting on an increasingly warm land. Here, we characterized heat stress occurrence in breeding king penguins through behavioural observations (e.g. panting occurrence) and body temperature measurements. We observed that behavioural signs of heat stress are frequent in king penguins breeding in the sub-Antarctic region (> 20% of observations at mid-day), and that subcutaneous temperatures increase under high heat load, especially in penguins observed panting. Subcutaneous and core body temperatures were moderately correlated and both increased with heat load. Yet, their responses were not parallel since core body temperature is markedly less sensitive to heat load than subcutaneous temperature. Air temperature alone was a poor predictor of heat stress occurrence, whereas the combination of high solar radiation, low wind speed and high air temperatures provided the strongest predictive power. Finally, reproductive failures were more likely to occur on warmer days, suggesting that heat stress may have significant sublethal effects on adults that could ultimately affect population dynamics. O_FIG O_LINKSMALLFIG WIDTH=150 HEIGHT=200 SRC="FIGDIR/small/611977v3_ufig1.gif" ALT="Figure 1"> View larger version (95K): org.highwire.dtl.DTLVardef@26db91org.highwire.dtl.DTLVardef@119461dorg.highwire.dtl.DTLVardef@4a1d8forg.highwire.dtl.DTLVardef@1da9d96_HPS_FORMAT_FIGEXP M_FIG C_FIG

evolutionary biology↗

bioRxiv2023

A synthetic elastic protein as molecular prosthetic candidate to strengthen vascular wall elasticity

The loss of elasticity is a hallmark of systemic aging or genetic syndromes (e.g. cutis laxa, Williams-Beuren and supravalvular aortic stenosis) with direct consequences on tissue functions, and particularly deleterious when associated to the cardiovascular system. Tissue elasticity is mainly provided by large elastic fibers composed of supramolecular complexes of elastin and microfibrils. In arteries, the mature elastic fibers are located in the media compartment and form concentric elastic lamellar units together with the smooth muscle cells (SMCs). The main function of vascular elastic fibers is to allow extension and recoil of the vessel walls in response to the intraluminal pressure generated by the blood flow following cardiac systole. The synthesis of elastic fibers (elastogenesis) mainly occurs during the last third of fetal life with a peak in the perinatal period and then slowly decreases until the end of growth; as a result, elastic fiber repair is almost non-existent in adults. To date, no treatment exists to restore or repair deficient or degraded elastic fibers. A few pharmacological compounds have been proposed, but their efficacy/side effects balance remains very unfavorable. As an alternative strategy, we developed a synthetic elastic protein (SEP) inspired by the human tropoelastin, the elastin soluble precursor, to provide an elastic molecular prosthesis capable of integrating and reinforcing endogenous elastic fibers. The SEP was easily produced in E. coli and purified by inversed transition cycling method. The resulting 55 kDa protein recapitulates the main physicochemical properties of the tropoelastin as thermal responsiveness, intrinsically disordered structures, and spherical self-assembly. The cross-linked SEP displays linear elastic mechanical properties under uniaxial tension loads. Using a co-culture in vitro model of the endothelial barrier, our results show that SEP is able to cross the cohesive endothelial monolayer to reach underlying SMCs. Moreover, SEP is processed by SMCs through a lysyl oxidase-dependent mechanism to form fibrillar structures that colocalize with fibrillin-rich microfibrils. The SEP was further characterized in vivo through the zebrafish model. The results indicate a global innocuity on zebrafish embryos and an absence of neutrophil recruitment following injection into the yolk sac of zebrafish. Finally, intravenous injection of a fluorescent SEP highlights its deposition in the wall of tortuous vessels which persists for several days after injection of the larvae. Taken together, our results demonstrate for the first time the incorporation of a naked tropoelastin-bioinspired polypeptide in endogenous elastic fibrillar deposits from SMCs, and its recognition by the lysyl- oxidase enzymatic machinery. In absence of toxicity and proinflammatory signal combined to a long-lasting accumulation in vessels in vivo, the SEP fulfills the first prerequisites for the development of an original biotherapeutic compound addressing the repair of elastic fibers.

cell biology↗

bioRxiv2023

Metabolic Dependency Shapes Bivalent Antiviral Response in Host Cells: The Role of Glutamine

The establishment of effective antiviral responses within host cells is intricately related to their metabolic status, shedding light on immunometabolism. In this study, we investigated the hypothesis that cellular reliance on glutamine metabolism contributes to the development of a potent antiviral response. We evaluated the antiviral response in the presence or absence of L-glutamine in the culture medium, revealing a bivalent response hinging on cellular metabolism. While certain interferon-stimulated genes (ISGs) exhibited higher expression in an oxidative phosphorylation (OXPHOS)-dependent manner, others were surprisingly upregulated in a glycolytic-dependent manner. This metabolic dichotomy was influenced in part by variations in IFN-{beta} expression. We initially demonstrated that the presence of L-glutamine induced an enhancement of OXPHOS in A549 cells. Furthermore, in cells either stimulated poly:IC or infected with Dengue Virus and Zika Virus, a marked increase in ISGs expression was observed in a dose-dependent manner with L-glutamine supplementation. Interestingly, our findings unveiled a metabolic dependency in the expression of specific ISGs. In particular, genes such as ISG54, ISG12 and ISG15 exhibited heightened expression in cells cultured with L-glutamine, corresponding to higher OXPHOS rates and IFN-{beta} signaling. Conversely, the expression of viperin and 2-5-oligoadenylate synthetase 1 was inversely related to L-glutamine concentration, suggesting a glycolysis-dependent regulation, confirmed by inhibition experiments. This study highlights the intricate interplay between cellular metabolism, especially glutaminergic and glycolytic, and the establishment of the canonical antiviral response characterized by the expression of antiviral effectors, potentially paving the way for novel strategies to modulate antiviral responses through metabolic interventions.

immunology↗