Biology subjects

Snoek, L. B.

Publications and source records attributed to Snoek, L. B..

5 recordsLinked to original sources

bioRxiv2026

EcoCore; An ecologically diverse panel of Arabidopsis thaliana accessions for studying plant-environment interactions

Arabidopsis thaliana naturally occurs across a wide geographic range and displays extensive natural variation in several traits including adaptive responses to the abiotic environment (e.g. temperature, drought, salt). Quantitative techniques like Genome Wide Association Studies (GWAS) enable mapping the genetic basis of such environmental responses and benefits from extensive genetic variation, but the size of the chosen diversity panel is often limited by phenotyping capacity. Most studies therefore use subpanels, often based on maximization of genetic diversity. However, this type of selection may overrepresent cosmopolitan alleles and underrepresent rare environment-specific alleles. Here, we demonstrate that the genetic variation in a GWAS subpanel of Arabidopsis thaliana accessions depends almost entirely on the number of accessions in the panel and very little on the composition of the panel. We present the EcoCore panel designed by grouping accessions of the 1001 genomes (1001G; 1135 accessions) collection, based on their native collection environment and selecting an equal number of accessions from each environment. We assessed hypocotyl lengths of plants grown at control and ambient high temperatures (20{degrees}C and 28{degrees}C) for 913 accessions of the 1001G and mapped these traits with the full 1001G panel versus the EcoCore panel. The EcoCore panel revealed novel genetic associations with hypocotyl length which is attributed to enrichment of alleles from rare environments. We present the EcoCore panel as a manageable resource for studying phenotypic plasticity and the genetic basis of plant-environment interactions.

plant biology↗

bioRxiv2022

Two sides to every coin: complementary introgression line populations in Caenorhabditis elegans

Quantitative genetics seeks to understand the role of allelic variation in trait differences. Introgression lines (ILs) contain a single genetic locus introgressed into another genetic background, and are one of the most powerful quantitative trait locus (QTL) mapping designs. However, albeit useful for QTL discovery, this homogenous background confounds genetic interactions. Here, we created an IL population with N2 segments in a CB4856 background (ILCB4856), reciprocal to an N2 background with CB4856 introgressions population (ILN2). The ILCB4856 panel comprises a population of 145 strains with sequencing confirmed N2 introgressions in a CB4856 background. A core set of 87 strains covering the entire genome was selected. We present three experiments demonstrating the power of the reciprocal IL panels. First, we performed QTL mapping identifying new regions associated with lifespan. Second, the existence of opposite-effect loci regulating heat-stress survival is demonstrated. Third, by combining ILN2 and ILCB4856 strains, an interacting expression QTL was uncovered. In conclusion, the reciprocal IL panels are a unique and ready-to-use resource to identify, resolve, and refine complex trait architectures in C. elegans.

genetics↗

bioRxiv2019

Dissecting the eQTL micro-architecture in Caenorhabditis elegans

The study of expression quantitative trait loci (eQTL) using natural variation in inbred populations has yielded detailed information about the transcriptional regulation of complex traits. Studies on eQTL using recombinant inbred lines (RILs) led to insights on local and distant regulatory loci of transcript abundance. However, determining the underlying causal polymorphic genes or variants is difficult, but ultimately essential for the understanding of regulatory networks of complex traits. This requires insight into whether associated loci are single eQTL or a combination of closely linked eQTL, and how this QTL micro-architecture depends on the environment. We addressed these questions by mapping eQTL in N2 x CB4856 C. elegans RIL populations across three different environments (control, heat-stress, and recovery). To test for independent replication of the RIL eQTL, we used introgression lines (ILs). Both populations indicate that the overall heritability, number, and position of eQTL differed among environments. Across environments we were able to replicate 70% of the local- and 40% of the distant-eQTL using the ILs. Simulation models revealed that additive effects explain up to 60-93% of RIL/IL heritability across environments. Closely linked eQTL explained up to 40% of RIL/IL heritability in the control environment whereas only 7% in the heat-stress and recovery environments. In conclusion, we show that reproducibility of eQTL was higher for local vs. distant eQTL and that the environment affects the eQTL micro-architecture.

genetics↗

bioRxiv2018

C. elegans genetic background modifies the core transcriptional response in an α-synuclein model of Parkinson’s disease

Accumulation of protein aggregates is a major cause of Parkinsons disease (PD), a progressive neurodegenerative condition that is one of the most common causes of dementia. Transgenic Caenorhabditis elegans worms expressing the human synaptic protein -synuclein show inclusions of aggregated protein and replicate the defining pathological hallmarks of PD. It is however not known how PD progression and pathology differs among individual genetic backgrounds. Here, we compared gene expression patterns, and investigated the phenotypic consequences of transgenic -synuclein expression in five different C. elegans genetic backgrounds. Transcriptome analysis indicates that the effects of -synuclein expression on pathways associated with nutrient storage, lipid transportation and ion exchange depend on the genetic background. The gene expression changes we observe suggest that a range of phenotypes will be affected by -synuclein expression. We experimentally confirm this, showing that the transgenic lines generally show delayed development, reduced lifespan, and an increased rate of matricidal hatching. These phenotypic effects coincide with the core changes in gene expression, linking developmental arrest, mobility, metabolic and cellular repair mechanisms to -synuclein expression. Together, our results show both genotype-specific effects and core alterations in global gene expression and in phenotype in response to -synuclein. We conclude that the PD effects are substantially modified by the genetic background, illustrating that genetic background mechanisms should be elucidated to understand individual variation in PD.

genomics↗

bioRxiv2017

A Point Of No Return Leading To Death During Heat-Shock In C. elegans

There is considerable insight into pathways and genes associated with heat-stress conditions. Most genes involved in stress response have been identified using mutant screens or gene knockdowns. Yet, there is limited understanding of the temporal dynamics of global gene expression in stressful environments. Here, we studied global gene expression profiles during 12 hours of heat stress in the nematode C. elegans. Using a high-resolution time series of increasing stress exposures, we found a distinct shift in gene expression patterns between 3-4 hours into the stress response, separating an initially highly dynamic phase from a later relatively stagnant phase. This turning point in expression dynamics coincided with a phenotypic turning point, as shown by a strong decrease in movement, survival and, progeny count in the days following the stress. Both detectable at transcriptional and phenotypic level, this study pin-points a relatively small time frame during heat stress at which enough damage is accumulated, making it impossible to recover the next few days.

genomics↗