Using a combination of sequencing technologies, a team led by scientists from Boston Children's Hospital identify hundreds of somatic single-nucleotide variants (sSNVs) that they used to track human embryonic development at high resolution. In their study, which appears in Science, the researchers performed high-depth whole-genome sequencing on multiple tissues from three individuals to identify sSNVs that can act as "endogenous barcodes" within single cells to reconstruct early embryonic cell divisions. They then conducted targeted sequencing of clonal sSNVs in various organs and more than 1,000 cortical single cells, plus single-nucleus RNA sequencing and single-nucleus assay for transposase-accessible chromatin sequencing of around 100,000 cortical single cells, revealing asymmetric contributions of early progenitors to extra-embryonic tissues, distinct germ layers, and organs. "Our analysis shows that hundreds of sSNVs occurring over several postzygotic cell divisions mark the landmarks of embryonic human development and inform the patterns of clonal distribution within and between organs and tissues," they write.
By sequencing the genome of the giraffe and comparing it to the genomes of related animals, a team led by researchers from Northwestern Polytechnical University in China have uncovered new details about the adaptations that enable the giraffe's towering stature. While the giraffe's height provides advantages such as the ability to access food sources out of reach for other animals, its unique anatomy creates physiological challenges, particularly regarding cardiovascular functions. To understand how the giraffe manages to thrive at such heights, the scientists created a high-quality chromosome-level giraffe genome that they compared the okapi and other ruminant genomes to uncover a list of giraffe-specific mutations related to cardiovascular, bone growth, vision, hearing, and circadian functions. Among these is a gene with seven unique amino acid substitutions not found in any other ruminant that, when introduced into mice, results in exceptional hypertension resistance and higher bone mineral density. The results, the study's authors write in Science Advances, will not only improve our understanding of the molecular mechanisms underpinning distinct giraffe traits but may provide insights into the study of hypertension in humans. GenomeWeb has more on this, here.