Biology subjects

Lougheed, D. R.

Publications and source records attributed to Lougheed, D. R..

3 recordsLinked to original sources

bioRxiv2024

Insights on macrosynteny, 'rebel' genes, and a new sex-linked region in anurans from comparative genomics and a new chromosome-level genome for the western chorus frog

Amphibians have unique genome characteristics including slow karyotypic evolution and cytogenetically undifferentiated sex chromosomes. Yet our understanding of amphibian genomes has not kept pace with that of mammals and birds, partially due to scarce genomic resources and challenges associated with large genome sizes and high repetitiveness. We assembled and annotated a chromosome-level genome for the western chorus frog (Pseudacris triseriata), a species of conservation concern and importance in evolutionary research. Comparison of our new genome with other chromosome-level frog genomes reveals exceptionally conserved evolution of 13 chromosomal elements and gene orders across over 200 million years of anuran evolution. We uncovered rebel Benchmarking Universal Single-Copy Orthologs (BUSCO) genes that have been duplicated in almost all frog species, have been transposed, and showed lineage-specific synteny patterns - possibly relating to key traits such as frog advertisement calls and mitochondrial genome evolution. We also assembled a complete mitochondrial genome and found heteroplasmy of both point polymorphisms and length variation in the tandem repeat arrays in the control region. Double-digest restriction-site associated DNA sequencing analysis indicates that the western chorus frog has an XY sex system and the sex-linked region involved an [~]1Mb indel structural variant. Overall, our study provides important genomic resources for treefrogs and other anurans, documents highly conserved chromosomal evolution and gene orders in anurans, identifies rebel genes that might be important for frog evolution, and reveals a new sex-linked region with indel structural variants in anurans.

genomics↗

bioRxiv2023

How to barcode (almost all) freshwater biodiversity

Freshwater ecosystems are complex, diverse and face a variety of imminent threats that have led to changes in both ecosystem structure and function. It is urgent that we develop and standardize monitoring tools allowing for rapid and comprehensive assessment of freshwater communities to understand their changing dynamics and to inform conservation. Environmental DNA surveys offer a means to inventory and monitor aquatic diversity, yet most studies focus on one or a few taxonomic groups only. In this study, we sought to 1) identify thoroughly validated, cost-efficient primer pair combinations that maximize detection of broad swaths of freshwater diversity, and 2) facilitate future primer pair selection by creating a free online and user-friendly tool. We first evaluated the completeness of public reference sequence databases and the efficiency of 14 primer pairs using an in silico approach, and then performed eDNA surveys using five mock communities (mix of DNA from tissues), water samples from aquarium samples with known taxonomic composition, and finally water samples from freshwater systems in Eastern Canada. We highlight the power of eDNA-based metabarcoding for reconstructing freshwater communities, including prey, parasite, pathogen, invasive, and declining species. Our work reveals the importance of the marker choice on species resolution, as well as the importance of degenerate primers, the length of the target fragment and the filtering parameters on detection success in water eDNA samples. Our new online tool SNIPe revealed that 13 to 14 primer pairs are necessary to recover 100% of the species in water samples (aquarium and natural systems), but four primer pairs are sufficient to recover almost 75% of taxa with little overlap. These results highlight the usefulness of eDNA for freshwater monitoring and should prompt more studies on tools to survey all-inclusive communities.

ecology↗

bioRxiv2023

EpiVar Browser: advanced exploration of epigenomics data under controlled access

MotivationHuman epigenomic data has been generated by large consortia for thousands of cell types to be used as a reference map of normal and disease chromatin states. Since epigenetic data contains potentially identifiable information, similarly to genetic data, most raw files generated by these consortia are stored in controlled-access databases. It is important to protect identifiable information, but this should not hinder secure sharing of these valuable datasets. ResultsGuided by the Framework for responsible sharing of genomic and health-related data from the Global Alliance for Genomics and Health (GA4GH), we have developed a tool to facilitate the exploration of epigenomics datasets aggregate results, while filtering out identifiable information. Specifically, the EpiVar Browser allows a user to navigate an epigenetic dataset from a cohort of individuals and enables direct exploration of genotype-chromatin phenotype relationships. Because the information about individual genotypes is not accessible and aggregated in the output that is made available, no identifiable data is released, yet the interface allows for dynamic genotype - epigenome interrogation. This approach has the potential to accelerate analyses that would otherwise require a lengthy multi-step approval process and provides a generalisable strategy to facilitate responsible access to sensitive epigenomics data. Availability and implementationOnline portal instance: https://computationalgenomics.ca/tools/epivar Source code: https://github.com/c3g/epivar-browser

genomics↗