Two new studies in Science combine single-cell RNA sequencing with either lineage tracing or a computational framework to link transcriptomes to future developmental trajectories.

Pathogens are wreaking havoc on bee populations. A study in Science describes how bacteria in the guts of bees can be engineered to protect their hosts from two particular pests, deformed wing virus and Varroa mites.

A new optogenetic approach called mRNA-LARIAT affords direct optogenetic control of localization and translation of specific mRNAs in living cells.

A study in Cell using a novel technique for detecting Neanderthal genes in the genomes of modern humans reveals early gene flow and migratory events between ancient Africans and Europeans.

How chromosomes are positioned and folded within the nucleus has implications for gene regulation. In this Review, Kempfer and Pombo describe and evaluate methods for studying chromosome architecture and outline the insights they are providing about nuclear organization.

Advances in sequencing- and imaging-based techniques for chromosome structure analysis have led to a mature understanding of bacterial chromosome structure and dynamics. In this Review, Dame, Rashid and Grainger discuss the hierarchical nature of bacterial chromosome structure and how it is influenced by diverse types of nucleoid-associated proteins. Furthermore, they describe roles for nucleoid-associated proteins and chromosome structure, including in gene expression, chromosome segregation and cell cycle regulation.

Although single reference genomes are valuable resources, they do not capture genetic diversity among individuals. Sherman and Salzberg discuss the concept of ‘pan-genomes’, which are reference genomes that encompass the genetic variation within a given species. Focusing particularly on large eukaryotic pan-genomes, they describe the latest progress, the varied methodological approaches and computational challenges, as well as applications in fields such as agriculture and human disease.

Adeno-associated virus (AAV) vector-mediated gene delivery has had long-term therapeutic effects for several diseases, including haemophilia and Duchenne muscular dystrophy. Genetically modifying AAV vectors to increase their transduction efficiency, vector tropism and ability to avoid the host immune response may further increase the success of AAV gene therapy.