Biology subjects

Luquet, E.

Publications and source records attributed to Luquet, E..

9 recordsLinked to original sources

bioRxiv2025

How does the somatic state influence plastic responses to predator cues within- and across generations?

The main dilemma facing prey is how to reduce predation risk while acquiring resources. Phenotypic plasticity, by modulating traits for acquiring resources and for defences, is a key process driving this trade-off. While there is ample evidence that predator-induced within-generational plasticity depends on resources, the relationship between resources and predator-induced transgenerational plasticity remains understudied. This study investigated how predator exposure and resource availability influence within- and trans-generational plasticity. We based our predictions on theories related to information- and state-based plasticity, two kinds of plasticity occurring in response to environmental information or alteration affecting somatic state, respectively. We conducted a two-generation laboratory experiment in the freshwater snail Physa acuta, manipulating predator cues and resource availability. Our results revealed that both types of plasticity participate in shaping the within- and transgenerational responses. Within a generation, the limited resource decreased the somatic state but did not constrain the defences. Across generations, the poor parental state decreased the offspring state even in high resource, which in turn decreased the absolute levels of their defences but increased their investment in reproduction. These results highlight the importance to integrate informational and state-based effects across generations to provide a more complete understanding of prey responses to predators.

ecology↗

bioRxiv2025

Cannot be male without complex I? Alteration in cellular metabolism involved in cytoplasmic male sterility in snail Physa acuta

Cytoplasmic male sterility (CMS) is a well-known example of mitonuclear genetic conflict over sex determination in hermaphrodite plants, where mitochondrial genes maternally inherited sterilize the male function while biparental inherited nuclear genes restore it. CMS has been recently discovered in wild animals, in the freshwater snail Physa acuta. In this species, CMS is associated with two extremely divergent mitogenomes D and K compared to the classical mitogenome N. D individuals are male-steriles, while male fertility is restored in K individuals. We hypothesized that the extreme divergence of mitogenomes associated with CMS can impact mitochondrial aerobic metabolism, a necessary process in eukaryotic organisms by which energy is transduced from food to ATP. Our results suggest that CMS might be associated with an alteration of co-encoded complex I in D male-sterile individuals, although partly compensated by the nuclear-encoded complex II. K restored hermaphrodites have an unaffected complex I respiration, but exhibit higher mitochondrial proton leak and higher relative anaerobic contribution to cellular metabolism, suggesting an energy cost of bearing CMS and restorer genes, which could underlie the reduced growth of K mitotype. How complex I alteration might induce male-sterility remains to be determined, but could be linked to oxidative stress or a defect in ATP-synthesis rate.

evolutionary biology↗

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

Temperature-dependant benefits and costs of cytoplasmic male sterility in snail Physa acuta

Cytoplasmic male sterility (CMS) originates from a mito-nuclear conflict where mitochondrial genes induce male sterility and nuclear genes restore male fertility in hermaphrodites. The first observation of CMS in animals was reported recently in the freshwater snail Physa acuta where it is associated with two extremes divergent mitotypes D and K. The D individuals are male-sterile while male-fertility is restored by nuclear genes in K and are found mixed with the most common male-fertile N mitotype in natural populations (i.e., gynodioecy). We compared male and female fitness, growth rate, and metabolism between the three mitotypes at two temperatures as this factor influences CMS in gynodioecious plants via alteration of mitochondrial functioning. Temperature did not affect male-sterility which depended only on the mitotype and the presence of restorers. Our results provided evidence that CMS is beneficial to female fitness in the absence of restorers, while it is costly in their presence, fulfilling a key theoretical condition for the long-term maintenance of gynodioecy. Fitness benefits and costs are mediated by differences in body mass and enhanced at cold temperature suggesting that the system dynamics may vary according to thermal conditions in nature.

evolutionary biology↗

bioRxiv2023

Metamorphosis reverses the risk-taking behavioral phenotype in moor frog along a latitudinal gradient

O_LIUnderstanding how demographic processes and environmental conditions shape behavioural variation across populations is pivotal in evolutionary ecology. However, the role that such processes play in the link between behaviour and life-history traits across populations remains largely unclear. C_LIO_LIThe moor frog (Rana arvalis) has colonized Sweden via two distinct routes from south via Denmark and from north via Finland. We collected R. arvalis eggs from multiple populations along a 1700 km latitudinal gradient across Northern Europe and raised tadpoles in a common garden experiment. We assessed developmental growth and proactivity levels in ca. 300 individuals at two key stages of anuran larval development: tadpoles (Gosner stage 32) and froglets (Gosner stage 46). C_LIO_LIWe found strong behavioural differences along the latitudinal gradient and between developmental stages. Tadpoles from northernmost populations were bolder (shorter times to leave a shelter) and showed higher activity levels in an open field test compared to those from southern populations. C_LIO_LIHowever, these behavioural patterns reversed at the froglet stage, with individuals from northern populations showing reduced proactivity that those from southern populations. Further analyses indicated significant associations between developmental growth and boldness, with contrasting patterns across developmental stages and colonization routes. C_LIO_LIIn line with recent revisitations of the pace-of-life syndrome theory (POLS) for animal personality, our findings suggest a decoupling of correlations between behaviour and life history traits across ontogeny, likely reflecting adaptive responses to divergent ecological and demographic constraints along the latitudinal gradient. C_LI

animal behavior and cognition↗

bioRxiv2021

C-STEM: ENGINEERING NICHE-LIKE MICRO-COMPARTMENTS FOR OPTIMAL AND SCALE-INDEPENDENT EXPANSION OF HUMAN PLURIPOTENT STEM CELLS IN BIOREACTORS

Human pluripotent stem cells (hPSCs) have emerged as the most promising cellular source for cell therapies. To overcome scale up limitations of classical 2D culture systems, suspension cultures have been developed to meet the need of large-scale culture in regenerative medicine. Despite constant improvements, current protocols relying on the generation of micro-carriers or cell aggregates only achieve moderate amplification performance. Here, guided by reports showing that hPSCs can self-organize in vitro into cysts reminiscent of the epiblast stage in embryo development, we developed a physio-mimetic approach for hPSC culture. We engineered stem cell niche microenvironments inside microfluidics-assisted core-shell microcapsules. We demonstrate that lumenized three-dimensional colonies maximize viability and expansion rates while maintaining pluripotency. By optimizing capsule size and culture conditions, we scale-up this method to industrial scale stirred tank bioreactors and achieve an unprecedented hPSC amplification rate of 282-fold in 6.5 days. TEASEROptimizing human pluripotent stem cells amplification by recapitulating and protecting biomimetic colonies in a bioreactor

bioengineering↗

bioRxiv2019

How past exposure to predation affects personality and behavioural plasticity?

When behaviour is observed multiple times on animals from the same population, between-individual difference in mean behaviour (personality) and in behavioural plasticity are often reported. While the developmental environment might explain such an individual difference, the effect of parental environment is still unexplored -a surprising observation as parental carry-over effect are now well-known to influence the average phenotype and plastic responses of offspring-. We tested whether parental and developmental exposure to predator cues impacted the immediate behavioural predator-induced response in the snail Physa acuta at both mean level (average response) and individual level (between-individual variation). Two generations of snails were reared in laboratory without or with exposure to predator cues. Then, escape behaviour was repeatedly assessed on adult snails in the presence or absence of predator cues. Both parental and developmental exposure to predator cues acted additively towards a lower average behavioural plasticity. At the individual level, developmental exposure induced higher differentiation in personality trait but not in behavioural plasticity while parental environment did not influence the between-individual differences. These results highlight that past environments can strongly influence behaviour at the population level and that they should be taken into consideration when investigating why individuals differ in behaviour.

animal behavior and cognition↗

bioRxiv2019

Chromatin structure changes in Daphnia populations upon exposure to environmental cues - or - The discovery of Wolterecks \"Matrix\"

Phenotypic plasticity is an important feature of biological systems that is likely to play a major role in the future adaptation of organisms to the ongoing global changes. It may allow an organism to produce alternative phenotypes in responses to environmental cues. Modifications in the phenotype can be reversible but are sometimes enduring and can even span over generations. The notion of phenotypic plasticity was conceptualized in the early 20th century by Richard Woltereck. He introduced the idea that the combined relations of a phenotypic character and all environmental gradients that influence on it can be defined as \"norm of reaction\". Norms of reaction are specific to species and to lineages within species, and they are heritable. He postulated that reaction norms can progressively be shifted over generations depending on the environmental conditions. One of his biological models was the water-flee daphnia. Woltereck proposed that enduring phenotypic modifications and gene mutations could have similar adaptive effects, and he postulated that their molecular bases would be different. Mutations occurred in genes, while enduring modifications were based on something he called the Matrix. He suggested that this matrix (i) was associated with the chromosomes, (ii) that it was heritable, (iii) it changed during development of the organisms, and (iv) that changes of the matrix could be simple chemical substitutions of an unknown, but probably polymeric molecule. We reasoned that the chromatin has all postulated features of this matrix and revisited Wolterecks classical experiments with daphnia. We developed a robust and rapid ATAC-seq technique that allows for analyzing chromatin of individual daphnia and show here (i) that this technique can be used with minimal expertise in molecular biology, and (ii) we used it to identify open chromatin structure in daphnia exposed to different environmental cues. Our result indicates that chromatin structure changes consistently in daphnia upon this exposure confirming Wolterecks classical postulate.

evolutionary biology↗

bioRxiv2019

Transgenerational plasticity of inducible defenses: combined effects of grand-parental, parental and current environments

While an increasing number of studies highlights that parental environment shapes offspring phenotype (transgenerational plasticity TGP), TGP beyond the parental generation has received less attention. Studies suggest that TGP impacts population dynamics and evolution of phenotype, but these impacts will depend on how long an environmental effect can persist across generations and whether multigenerational effects are cumulative. Here we tested the impact of both grand-parental and parental environments on offspring reaction norm in a prey-predator system. We exposed three generations of Physa acuta snails without and with predator-cues according to a full factorial design and measured offspring inducible defenses. We found that both grand-parental and parental exposure to predator cues impacted offspring anti-predator defenses, but their effects were not cumulative and depended on the defenses considered. We also highlighted that grand-parental environment could alter reaction norm of offspring shell thickness, demonstrating an interaction between the grand-parental TGP and the within-generational WGP plasticity. We called for more studies covering the combine effects of multigenerational environments.

evolutionary biology↗