Biology subjects

Volckaert, F. A. M.

Publications and source records attributed to Volckaert, F. A. M..

3 recordsLinked to original sources

bioRxiv2024

Spleen gene expression is associated with mercury content in three-spined stickleback populations

Mercury can be very toxic at low environmental concentrations by impairing immunological, neurological, and other vital pathways in humans and animals. Aquatic ecosystems are heavily impacted by mercury pollution, with evidence of biomagnification through the food web. We examined the effect of mercury toxicity on the spleen, one of the primary immune organs in fish, in natural populations of the three-spined stickleback (Gasterosteus aculeatus Linnaeus, 1758). Our aim was to better understand adaptation to high mercury environments by investigating transcriptomic changes in the spleen. Three stickleback populations with mean Hg muscle concentrations above and three populations with mean Hg muscle concentrations below the European Biota Quality Standard of 20 ng/g wet weight were selected from the Scheldt and Meuse basin in Belgium. We then conducted RNA sequencing of the spleen tissue of 22 females from these populations. We identified 136 differentially expressed genes between individuals from populations with high and low mean mercury content. The 129 genes that were upregulated were related to the neurological system, immunological activity, hormonal regulation, and inorganic cation transporter activity. Seven genes were downregulated and were all involved in pre-mRNA splicing. The results are indicative of our ability to detect molecular alterations in natural populations that exceed an important environmental quality standard. This allows us to assess the biological relevance of such standards, offering an opportunity to better describe and manage mercury-associated environmental health risks in aquatic populations.

ecology↗

bioRxiv2024

First evidence of a causal link between genetic variation and thermal adaptation in a schistosome host snail

Freshwater snails are pivotal in transmitting schistosomiasis, a tropical parasitic disease affecting over 150 million people. The adaptive potential of these snails is a critical factor in determining how climate change and other environmental factors influence disease transmission dynamics, yet it has remained unexplored. Bulinus truncatus is the schistosome intermediate host snail with the widest geographic distribution and therefore plays a pivotal role in determining the maximum range of urogenital schistosomiasis. In this study, we assessed the local adaptation capacity of B. truncatus to temperature through an integrative approach encompassing phenotypic, ecophysiological, and genomic data. Ten snail populations from diverse thermal environments were collected in three countries, with eight populations reared in a common garden. The F2 generation (total N= 2592) was exposed to eight chronic temperature treatments and various life-history traits were recorded for over 14 weeks. Subsequently, ecophysiological analyses were conducted on the ten last surviving snails per population. Genotyping the parental generation collected in the field using a genotyping-by-sequencing (GBS) approach, revealed 12,875 single nucleotide polymorphisms (SNPs), of which 4.91 % were potentially under selection. We observed a significant association between these outlier SNPs, temperature, and precipitation. Thermal adaptations in life-history traits were evident, with lower survival rates at high temperatures of warm- origin snails compensated for by higher reproduction rates. Cold-origin snails, on the other hand, exhibited higher growth rates adapted to a shorter growing season. Ecophysiological adaptations included elevated sugar and haemoglobin contents in cold-adapted snails. In contrast, warm-adapted snails displayed increased protein levels but also more oxidative damage. Furthermore, heightened phenoloxidase levels indicated a more robust immune response in snails from parasite-rich regions. The substantial local adaptation capacity of B. truncatus holds profound implications for its response to climate change, future schistosomiasis risk, and the effectiveness of schistosomiasis control measures. HighlightsO_LILocal adaptation influences species responses to climate change C_LIO_LIThe snail Bulinus truncatus showed a high thermal local adaptation (LA) potential C_LIO_LILA is apparent through variations in life history and ecophysiological traits C_LIO_LIWe identified a significant genetic basis underlying this LA C_LIO_LILA of the hosts could sustain schistosomiasis transmission under global warming C_LI

ecology↗

bioRxiv2021

Facilitating population genomics of non-model organisms through optimized experimental design for reduced representation sequencing

Genome-wide data are invaluable to characterize differentiation and adaptation of natural populations. Reduced representation sequencing (RRS) subsamples a genome repeatedly across many individuals. However, RRS requires careful optimization and fine-tuning to deliver high marker density while being cost-efficient. The number of genomic fragments created through restriction enzyme digestion and the sequencing library setup must match to achieve sufficient sequencing coverage per locus. Here, we present a workflow based on published information and computational and experimental procedures to investigate and streamline the applicability of RRS. In an iterative process genome size estimates, restriction enzymes and size selection windows were tested and scaled in six classes of Antarctic animals (Ostracoda, Malacostraca, Bivalvia, Asteroidea, Actinopterygii, Aves). Achieving high marker density would be expensive in amphipods, the malacostracan target taxon, due to the large genome size. We propose alternative approaches such as mitogenome or target capture sequencing for this group. Pilot libraries were sequenced for all other target taxa. Ostracods, bivalves, sea stars, and fish showed overall good coverage and marker numbers for downstream population genomic analyses. In contrast, the bird test library produced low coverage and few polymorphic loci, likely due to degraded DNA. Prior testing and optimization are important to identify which groups are amenable for RRS and where alternative methods may currently offer better cost-benefit ratios. The steps outlined here are easy to follow for other non-model taxa with little genomic resources, thus stimulating efficient resource use for the many pressing research questions in molecular ecology.

genomics↗