Eurasian common shrews (Sorex araneus) show a seasonal reduction of brain and organ size, called Dehnel’s phenomenon. Researchers combined a chromosome-scale genome assembly with seasonal brain transcriptomes to connect genetic structure with seasonal changes in gene activity.
The Genome Research paper reports that, from autumn into winter, shrews show regulatory shifts in oxidative phosphorylation and increased fatty acid metabolism, patterns also seen in hibernating species. The animals had elevated winter expression of genes for gluconeogenesis, and the authors found increased FOXO signaling. The team concludes that gluconeogenesis together with overexpression of FOXO is central to the organ and brain shrinkage.
The Molecular Biology and Evolution study examined how chromosome arrangement may enable this plasticity. It identified gene expression changes that appear to drive Dehnel’s phenomenon and found that genes with positive selection and differential expression in the hippocampus are overrepresented at open chromosome regions that experience more breaks. The authors suggest chromosomal rearrangements are part of adaptive evolution and regulation of brain size plasticity.
The studies note that the same genes exist in humans and that studying shrew energy management and brain regrowth could inform research on metabolism and brain health. Collaborators include several international institutions and the source is Stony Brook University.
Difficult words
- transcriptome — all RNA molecules made by cellstranscriptomes
- oxidative phosphorylation — cell process that makes energy in mitochondria
- gluconeogenesis — production of glucose from non-sugar sources
- gene expression — process of using DNA to make RNA
- chromosomal rearrangement — change in chromosome order or structurechromosomal rearrangements
- hippocampus — part of the brain involved in memory
- positive selection — evolution process favoring beneficial genes
- plasticity — ability to change structure or function
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could studying shrew energy management and brain regrowth help research on human metabolism or brain health?
- What advantages might seasonal brain and organ shrinkage give small animals like shrews?
- The studies involve several international institutions. Do you think international collaboration is important for this kind of research? Why?
