Volume 608

  • No. 7922 11 August 2022

    Sticking points

    Interfaces between cells are created when cells stick to each other, a process usually mediated by adhesion molecules called adhesins. Engineering the formation of cell–cell interfaces and programming subsequent patterning using synthetic adhesins has proved challenging. In this week’s issue, Ingmar Riedel-Kruse and his colleagues present such a system based on synthetic adhesins in the bacterium Escherichia coli. The researchers used the four-colour theorem to mathematically and experimentally show that just four adhesins are sufficient to construct a logic to create any arbitrary interface pattern. The cover shows one such tiling pattern. Each dot corresponds to a colony of outwardly growing E. coli, and the lines are the interfaces formed when two bacteria carrying complementary adhesins meet and stick together. The adhesin logic is illustrated by the coloured shapes overlaid on part of the image. The four-adhesin toolkit could help drive the engineering of biosensors and biomaterials as well as shedding light on the evolution of multicellular systems.

  • No. 7921 4 August 2022

    Capital gains

    An individual’s social network and community — their ‘social capital’ — has been thought to influence outcomes ranging from earnings to health. But measuring social capital is challenging. In two papers in this week’s issue, Raj Chetty and his colleagues use data on 21 billion friendships from Facebook to construct a Social Capital Atlas containing measures of social capital for each ZIP code, high school and college in the United States. The researchers measure three types of social capital: connectedness between different types of people, social cohesion and civic engagement. They find that children who grow up in communities where people of low and high socio-economic status interact more have substantially greater chances of rising out of poverty. The team then examines what might limit social interactions across class lines, finding a roughly equal contribution from lack of exposure — because children in different socio-economic groups go to different schools, for example — and friending bias, the tendency for people to befriend people similar to them.