Biology subjects

Lacoue-Labarthe, T.

Publications and source records attributed to Lacoue-Labarthe, T..

4 recordsLinked to original sources

bioRxiv2025

Two de novo transcriptome assemblies and functional annotations from juvenile cuttlefish (Sepia officinalis) under various metal and pCO2 exposure conditions

AO_SCPLOWBSTRACTC_SCPLOWThe cuttlefish Sepia officinalis is a precious model in behavioural and neurobiology studies. It is currently facing combined environmental changes related to the anthropogenic global change. However, genomic resources available to support investigations tackling this issue are still scarce. Therefore, we present two annotated de novo transcriptome assemblies from recently hatched (whole body) and one-month-old (head) Sepia officinalis juveniles. Both assemblies rely on an important read depth validated by a pseudo-rarefaction analysis, and gathered several individuals from various metal and pCO2 exposure conditions. After redundancy reduction, assemblies from newly hatched and one-month-old individuals comprised 230,672 and 370,613 transcripts with 35,590 and 44,233 putative ORFs, respectively, and an annotation rate arounf 70%. Assemblies were compared to each other, revealing age-specific transcriptomic landscapes. These two assemblies constitute highly valuable genomic resources complementing reference genome assembly and facilitating the investigation of transcriptomic endpoints in environmental studies considering coleoid cephalopods.

genomics↗

bioRxiv2023

Assimilation efficiencies and elimination rates of trace metals accumulated by trophic pathway in Gammarus fossarum

To improve the assessment of metal toxicity in aquatic organisms, it is important to consider the different uptake pathways (i.e. trophic or aqueous). The bioaccumulation of dissolved metals such as Cd and Zn in gammarids is beginning to be well described. However, there are very few data on the contribution of the dietary pathway, and its associated toxicokinetic parameters. Among these, the assimilation efficiency (AE) is an essential parameter for the implementation of models that take the trophic pathway into account. This study aims to estimate the assimilation efficiencies and elimination rates of two types of food, i.e. alder leaves and chironomid larvae, contaminated with three metals (Ag, Cd and Zn) of major concern for the Water Framework Directive (WFD). The pulse-chase-feeding method was used. Gammarids were fed with alder leaves or chironomid larvae previously contaminated with 110mAg, 109Cd or 65Zn, for a short period of time (1 to 5 hours), followed by an elimination phase of 14 days. At different time points, the gammarids were placed alive on the gamma detector to individually quantify whole body concentrations of 110mAg, 109Cd or 65Zn. Our results indicate that: i) Cd has the highest assimilation efficiency (39% for leaves and 19% for larvae), followed by Zn (15% for leaves and 9% for larvae) and Ag (5% for leaves); ii) for Cd and Zn, the AE were higher when gammarids were fed with leaves than with larvae; iii) the elimination rates of metals seem to depend more on the food matrix than on the metal assimilated; and thus iv) the biological half-life calculated from the kes is 5.1 days for Ag, between 4.9 and 13 days for Cd and between 3.8 and 13 days for Zn.

physiology↗

bioRxiv2022

Hydrothermal sulphur bacteria enhance mercury availability for coastal marine organisms

The hydrothermal compounds massively released into the sea by the geothermal power plant of Bouillante (Guadeloupe, Lesser Antilles) support the growth of sulphur-oxidising bacteria like around black smokers. Opportunistic animals of the bay were previously shown to actively seek and consume the bacterial biofilm. To investigate the role of these bacterial mats in enhancing the transfer of Hg, a highly toxic heavy metal, its concentrations were assessed in sediments, bacteria, and 6 low trophic levels animals from the Bouillante Bay and a Control Site nearby containing only natural sources of Hg. Concentrations of Hg in all samples from Bouillante were greater than those from the Control Site (2 to 627 times higher). A comparison with the Hg concentrations reported in the literature for similar samples types reveals that they are abnormally high in most Bouillante samples. Although bacterial biofilm contained high levels of Hg, the link between bacteria contribution to diet and Hg concentration was more complex than expected, which might be due to interspecific differences in Hg uptake and elimination rates. Species not consuming bacteria (i.e. filter feeders) still presented higher levels of Hg, suggesting that significant amounts of Hg are released along with discharge waters from the Bouillante geothermal plant, and are integrated through diffusion. Differences in Hg concentrations between tissues do not indicate that Hg contained in samples from animals was under the form of MeHg, lowering the biomagnification potential of Hg in the Bouillante Bay trophic food web. Overall, the Bouillante case study emphasises for the first time an important role played by sulphur bacteria mats as a vector of hydrothermal inorganic Hg, and potentially other trace metals emitted in vents area, through dietary pathways.

ecology↗

bioRxiv2020

Habitat filtering differentially modulates phylogenetic vs functional diversity relationships between dominant ground-dwelling arthropods in salt marshes

While mechanisms underlying biological diversities at different scales received huge attention over the last decades, whether local abiotic factors driving functional and phylogenetic diversities can differ among ecologically and phylogenetically closely related taxa remains under-investigated. In this study, we compared correlations and drivers of functional (FD) and phylogenetic (PD) diversities between two dominant taxa of ground-dwelling arthropods in salt marshes, spiders and carabids. Pitfall trapping in two sampling sites of N-W France resulted in the collection and identification of more than 7000 individuals belonging to 67 species. Morphological and behavioral traits, as well as molecular sequences of COI gene, were attributed to all species for calculating functional and phylogenetic diversities respectively. Both taxa exhibited high correlation between FD and PD, which was even higher in carabids probably due to their lower species richness. Analyses using Bayesian framework and structural equation modeling revealed that FD and PD were positively influenced by taxonomic diversity in spiders and carabids, but abiotic factors driving FD and PD differed between taxa. Salinity especially drove the taxonomic diversity of carabids, but not that of spiders, suggesting that spiders are more plastic and less selected by this factor. Phylogenetic diversity was conversely influenced by salinity in spiders but not in carabids. This interesting result can be interpreted by different evolutionary history and colonization process of salt marshes between the two model taxa. Our study finally highlights that, even in taxa of the same phylum and occupying the same niche in a highly constrained habitat, functional and phylogenetic diversities can have different drivers, showing different filtering mechanisms and evolutionary history at small spatial and temporal scales.

ecology↗