NEW FINDINGS — GENETICS AND GENOMICS
An Ancient Appetite
Enzymes are essential for digestion, breaking down
complex foods into smaller, usable molecules. Amylase, an enzyme pro- duced in saliva and the pancreas, converts dietary starches into sugars. The gene AMY1 encodes salivary amylase. AMY1 genes are clustered on chromosome 1, a region prone to DNA duplication and rearrangement. The number of AMY1 copies varies widely among individuals and has increased over time. Scientists have long hypothesized that rising AMY1 gene copies align with our transition to agriculture and starch-rich diets. However, studying this region has been difficult due to its repetitive structure. Using advanced technologies like long-read sequencing and optical genome mapping, researchers analyzed 98 modern genomes, uncovering 30 unique versions of the amylase region. They found the number of AMY1 gene copies ranged from 2 to 16 per person. Ancient DNA analysis revealed that multiple AMY1 gene copies existed long before agriculture. The 45,000-year-old Ust’-Ishim man had six copies, and some Neanderthals had three. While initial gene duplications occurred before humans split from Neanderthals, copy numbers rose significantly after farming began. Neolithic humans had fewer copies than post-agricultural populations, highlighting adaptation to starch-heavy diets. This research highlights the dynamic relationship between the human genome and environment and may lead to further understanding of individual variations in metabolism and diet. n
Old Genes, New Mice Stem cells can develop into many different types of cells in multicellular organisms. They have the unique ability to divide and differentiate into specialized cell types, which is important for embryonic development, as well as growth and tissue repair throughout an organism’s life. Understanding stem cell biology is important because it could help explain how some diseases develop and how to best treat them. In a ground-breaking effort, researchers have recreated mouse stem cells using genes from choanoflagellates, single-celled organ- isms considered the closest living relatives of animals. They have ancient versions of Sox and POU genes, which control a stem cell’s ability to differentiate into other types of cells, a phenomenon called pluripotency. While it is peculiar that a single-celled organism would have genes for cell differentiation, the researchers were able to leverage it in their experiments. They replaced an essential gene ( Sox2 ) in mouse cells with the ancient version from choanoflagellates, successfully reprogram- ming them into stem cells. The modified stem cells were injected into developing mouse embryos. The resulting mice displayed traits from both the embryo and the newly introduced engineered cells, confirming the ancient gene’s functional role in pluripotency. This discovery challenges the idea that genes responsible for cell differentiation evolved exclusively within animals. This experiment revealed that genetic tools for stem cell formation were already present in unicellular ancestors long before multicellular life. These genes functioned remarkably similarly across a billion years of evolution, which shows the flexibility of genetic mechanisms and how they are recycled for new functions during evolution. The research has impacts beyond a better understanding of the mechanisms of evolution. It also paves the way for new biotechnology tools where manufactured forms of Sox and POU genes might perform better than their natural counterparts. A better understanding of stem cell formation could lead to new therapies and reprogramming cells to treat disease or repair cell damage. n
REFERENCE: Yilmaz F, et al., Reconstruction of the human amylase locus reveals ancient duplications seeding modern-day variation. Science . [2024] 386{6724):eadn0609. https://www.science.org/doi/10.1126/science.adn0609?urlver=Z39.88-2003&r- fr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed
REFERENCE: "Scientists recreate mouse from gene older than animal life." ScienceDaily , 18 November 2024. Accessed 14 January 2025. https://www.sciencedaily. com/releases/2024/11/ 241118125716.htm
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