Biology subjects

Corthals, A. P.

Publications and source records attributed to Corthals, A. P..

4 recordsLinked to original sources

bioRxiv2025

Gene expression reveals the pancreas of Aselli as a critical organ for plasma cell differentiation in the common shrew

Almost all mammals rely on the thymus and bone marrow to generate and differentiate B- and T cells essential for adaptive immunity. A few members of the family Soricidae, or true shrews, have also evolved the pancreas of Aselli, a kidney-sized organ hypothesized to serve this primary immune role, and whose gene expression profile is unknown. Here we introduce transcriptomes of juvenile Sorex araneus pancreas of Aselli, compare them to those of the spleen and chick bursa of Fabricius, an analogous and bird-specific organ, and explore differential expression overlaps with positively selected genes. While differential gene expression analyses revealed overexpression of genes that regulate the differentiation of B cells into long-term plasma cells (e.g., IRF4, XBP1, PRDM1) compared to the spleen and more convergent expression with the bursa of Fabricius than expected by chance (including IRF4), overlaps with positive selection were as expected and included PTPRCAP, which regulates both T and B cell antigen responses and lymph node size. Our results support the specialized role of the pancreas of Aselli in adaptive immunity, and we propose this unique organ evolved at the intersection between extreme metabolic demands and high parasite burdens in tiny yet very active shrews.

evolutionary biology↗

bioRxiv2025

Seasonal brain regeneration and chromosome instability are linked to selection on DNA repair in Sorex araneus

Sorex araneus, the Eurasian common shrew, has seasonal brain size plasticity (Dehnels phenomenon) and abundant intraspecific chromosomal rearrangements, but genomic contributions to these traits remain unknown. We couple a chromosome-scale genome assembly with seasonal brain transcriptomes to discover relationships between molecular changes and both traits. Positively selected genes enriched the Fanconi anemia DNA repair pathway, which prevents the accumulation of chromosomal aberrations, and is likely involved in chromosomal rearrangements (FANCI, FAAP100). Genes involved in neurogenesis show either signatures of positive selection (PCDHA6), seasonal differential expression in the cortex and hippocampus (Notch signaling), or both (SOX9), suggesting a role for cellular proliferation in seasonal brain shrinkage and regrowth. Both positive selection and evolutionary upregulation in the shrew hypothalamus of VEGFA and SPHK2 indicate adaptations in hypothalamic metabolic homeostasis have evolved together with Dehnels phenomenon. These findings reveal genomic changes central to the evolution of both chromosomal instability and cyclical patterns in brain gene expression that characterizes mammalian brain size plasticity. TeaserGenomic and expression variations are key to chromosomal instability and seasonal brain plasticity in the common shrew.

evolutionary biology↗

bioRxiv2024

Seasonal and comparative evidence of adaptive gene expression in mammalian brain size plasticity

Contrasting almost all other mammalian wintering strategies, Eurasian common shrews, Sorex araneus, endure winter by shrinking their brain, skull, and most organs, only to then regrow to breeding size the following spring. How such tiny mammals achieve this unique brain size plasticity while maintaining activity through the winter remains unknown. To discover potential adaptations underlying this trait, we analyzed seasonal differential expression in the shrew hypothalamus, a brain region that both regulates metabolic homeostasis and drastically changes size, and compared hypothalamus expression across species. We discovered seasonal variation in suites of genes involved in energy homeostasis and apoptosis, shrew-specific upregulation of genes involved in the development of the hypothalamic blood brain barrier and calcium signaling, as well as overlapping seasonal and comparative gene expression divergence in genes implicated in the development and progression of human neurological and metabolic disorders, including CCDC22. With high metabolic rates and facing harsh winter conditions, Sorex araneus have evolved both adaptive and plastic mechanisms to sense and regulate their energy budget. Many of these expression changes mirrored those identified in human neurological and metabolic disease, highlighting the interactions between metabolic homeostasis, brain size plasticity, and longevity.

evolutionary biology↗

bioRxiv2019

Six new reference-quality bat genomes illuminate the molecular basis and evolution of bat adaptations

Bats account for ~20% of all extant mammal species and are considered exceptional given their extraordinary adaptations, including biosonar, true flight, extreme longevity, and unparalleled immune systems. To understand these adaptations, we generated reference-quality genomes of six species representing the key divergent lineages. We assembled these genomes with a novel pipeline incorporating state-of-the-art long-read and long-range sequencing and assembly techniques. The genomes were annotated using a maximal evidence approach, de novo predictions, protein/mRNA alignments, Iso-seq long read and RNA-seq short read transcripts, and gene projections from our new TOGA pipeline, retrieving virtually all (>99%) mammalian BUSCO genes. Phylogenetic analyses of 12,931 protein coding-genes and 10,857 conserved non-coding elements identified across 48 mammalian genomes helped to resolve bats closest extant relatives within Laurasiatheria, supporting a basal position for bats within Scrotifera. Genome-wide screens along the bat ancestral branch revealed (a) selection on hearing-involved genes (e.g LRP2, SERPINB6, TJP2), which suggest that laryngeal echolocation is a shared ancestral trait of bats; (b) selection (e.g INAVA, CXCL13, NPSR1) and loss of immunity related proteins (e.g. LRRC70, IL36G), including pro-inflammatory NF-kB signalling; and (c) expansion of the APOBEC family, associated with restricting viral infection, transposon activity and interferon signalling. We also identified unique integrated viruses, indicating that bats have a history of tolerating viral pathogens, lethal to other mammal species. Non-coding RNA analyses identified variant and novel microRNAs, revealing regulatory relationships that may contribute to phenotypic diversity in bats. Together, our reference-quality genomes, high-quality annotations, genome-wide screens and in-vitro tests revealed previously unknown genomic adaptations in bats that may explain their extraordinary traits.

genomics↗