The sequenced genome of the tuatara (Sphenodon punctatus), the only living member of the ancient reptilian order Rhynchocephalia, is reported in Nature this week. Found only in New Zealand, the tuatara represents a link to the now-extinct stem reptiles from which dinosaurs, modern reptiles, birds, and mammals evolved. To better understand amniote evolution, an international team led by scientists from the University of Otago sequenced the tuatara genome and compared it with genomes from other vertebrates. They find that the tuatara lineage diverged from that of snakes and lizards around 250 million years ago, and identify expansions of proteins and non-protein-coding RNA families, as well as a diversity of repeat elements that show a mix of reptilian and mammalian features.
Using single-cell RNA sequencing, a Jackson Laboratory for Genomic Medicine-led team has mapped the cell populations that give rise to the complex blood transcriptional signatures that characterize systemic lupus erythematosus (SLE). As reported in Nature Immunology, the investigators profiled around 276,000 peripheral blood mononuclear cells from 33 children with SLE with different degrees of disease activity, along with 11 matched controls. Increased expression of interferon-stimulated genes (ISGs) was observed in SLE cells versus healthy controls cells and was found to result from a small number of transcriptionally defined subpopulations within major cell types, particularly plasma cells. The researchers also observed expanded cell subpopulations enriched in ISGs and/or in monogenic lupus-associated genes among the sickest patients, a finding confirmed through the profiling of roughly 82,000 single peripheral blood mononuclear cells from adult SLE patients. Overall, the study provides a framework for SLE stratification and suggests that specific cell subpopulations may serve as potential therapeutic targets, the authors write.