Geographic-genomic and geographic-phenotypic differentiation of the Aquilegia viridiflora complex

How species diverge into different lineages is a central issue in evolutionary biology.Despite the increasing evidence indicating that such divergences do not need geographic isolation,the correlation between lineage divergence and the adaptive ecological divergence of phenotype corresponding to distribution is still unknown.In addition,gene flow has been widely detected during and through such diverging processes.We used one widely distributed Aquilegia viridiflora complex as a model system to examine genomic differentiation and corresponding phenotypic variations along geographic gradients.Our phenotypic analyses of 20 populations from northwest to northeast China identified two phenotypic groups along the geographic cline.All examined traits are distinct from each other,although a few intermediate individuals occur in their contacting regions.We further sequenced the genomes of representative individuals of each population.However,four distinct genetic lineages were detected based on nuclear genomes.In particular,we recovered numerous genetic hybrids in the contact regions of four lineages.Gene flow is widespread and continuous between four lineages but much higher between contacting lineages than geographically isolated lineages.Gene flow and natural selection might result in inconsistency between heredity and phenotype.Moreover,many genes with fast lineage-specific mutations were identified to be involved in local adaptation.Our results suggest that both geographic isolation and local selection exerted by the environment and pollinators may together create geographic distributions of phenotypic variations as well as the underlying genomic divergences in numerous lineages.

Single senescent cell sequencing reveals heterogeneity in senescent cells induced by telomere erosion

Dear Editor,Over a half-century ago,Dr.Leonard Hayflick described the phenotype of a finite lifespan for human fibroblasts being passaged in in vitro cell culture(Hayflick et al.,1961),a phenomenon today known as replicative cellular senescence.Cellular senescence has been defined as a state in which cells lose their potential to divide and are permanently arrested in either the G1,or arguably the G2 stage of the cell cycle(Mao et al.,2012).In addition to replicative cellular senescenee—which is induced by large amounts of DNA damage at telomeres due to loss of the specialized T-loop structure—xogenous sublethal stresses such as ionizing radiati on,genotoxic chemicals or hyper-activated on cogenes may also trigger a similar form of senescence,stress induced premature cellular senescenee(SIPS).

Single-cell RNA Sequencing Reveals Sexually Dimorphic Transcriptome and Type 2 Diabetes Genes in Mouse Islet β Cells

Type 2 diabetes(T2D)is characterized by the malfunction of pancreaticβcells.Susceptibility and pathogenesis of T2D can be affected by multiple factors,including sex differences.However,the mechanisms underlying sex differences in T2D susceptibility and pathogenesis remain unclear.Using single-cell RNA sequencing(scRNA-seq),we demonstrate the presence of sexually dimorphic transcriptomes in mouseβcells.Using a high-fat diet-induced T2D mouse model,we identified sex-dependent T2D altered genes,suggesting sex-based differences in the pathological mechanisms of T2D.Furthermore,based on islet transplantation experiments,we found that compared to mice with sexmatched islet transplants,sex-mismatched islet transplants in healthy mice showed down-regulation of genes involved in the longevity regulating pathway ofβcells.Moreover,the diabetic mice with sex-mismatched islet transplants showed impaired glucose tolerance.These data suggest sexual dimorphism in T2D pathogenicity,indicating that sex should be considered when treating T2D.We hope that our findings could provide new insights for the development of precision medicine in T2D.