High-quality genomes reveal new differences between the great apes

Abstract

the plexus into arteries and veins starts only after the plexus has connected to the aorta (the main heart artery), and therefore after the onset of blood flow 5 . But, unexpectedly, Su et al. found that several cells from their embryos, in which the plexus had not yet received blood, had a gene-expression profile associated with mature arteries. They called these cells pre-artery cells.The authors used a genetic strategy to indelibly label the pre-artery cells with a marker protein, such that these cells and the lineages they give rise to could be tracked during embryonic development. This lineage tracing revealed that, although most pre-artery cells did go on to form coronary arteries, some were incorporated into capillaries, which connect coronary arteries with veins. Thus, it seems that, although certain endo thelial cells are genetically predisposed to form arteries, they also have a degree of developmental plasticity (Fig. 1).Next, Su and colleagues performed a detailed analysis of the gene-expression patterns of cells on the developmental spectrum from sinus venosus to pre-artery cells. Changes in gene expression towards more arterial-like profiles occurred only gradually along most of the spectrum. However, there was a sharp change as cells crossed a threshold to adopt a pre-artery state. The researchers showed that the greatest difference in expression in pre-artery cells compared with other cells in their analysis occurred in genes implicated in regulating the cell cycle. Furthermore, in mouse embryos, pre-artery cells proliferated less than did cells in the plexus. Thus, limiting cell divisions might be a prerequisite for coronary artery maturation.