#tissue patterning

Gut Geometry

The human gut is approximately 20-feet long, yet it squeezes into our bodies. During development, the gut tube forms a reproducible looped pattern in order to fit into that space, suggesting that it’s controlled by our genes. How cells influence changes in the shape of whole organs isn’t easy to track, especially for internal organs like the gut! But researchers have developed a new imaging technique to analyse just that. They visualised the folding and elongation of the midgut of flies and generated time-lapse movies that show how the layers of muscle cells (yellow) and endodermal cells (blue) which will form the inner lining of the gut, interact to mould it into four chambers before starting to coil. With further analysis, they found that muscle constrictions that induce shape changes in the endodermal cells to form the chambers are triggered by signalling molecules controlled by Hox genes – known for controlling tissue pattern development.

Written by Sophie Arthur

Image from work by Noah P Mitchell and colleagues

Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, USA

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in eLife, May 2022

Spots and Stripes

Although they're almost identical in most respects, it’s easy to ‘spot’ the difference between these two species of Danio minnows. The top one, Danio quagga (named after the quagga, an extinct species of zebra) has a striped pattern of pigment cells in its skin, while the other – Danio kyathit, named after the Burmese word for ‘leopard’ – has spots. Both species are closely related to zebrafish (Danio rerio), which are often used in biomedical research as a model for more complex organisms. In fact, just a single genetic change can switch zebrafish from stripy to spotty. However, researchers studying how these patterns form during development have discovered that the genes responsible for creating spots and stripes in D. quagga and D. kyathit are more complicated than those in their zebrafish relatives, providing new insights into the underlying processes at work that control colouration, whether in fish or other animals.

Written by Kat Arney

Image from work by Braedan M. McCluskey and colleagues

Department of Biology, University of Virginia, Charlottesville, VA, USA

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in PLOS Genetics, April 2021

Film Time

Genes in developing animals and plants switch on or off – like paint brushes coming down and up on a page, they express different traits in different places at different times. Gradually an overall picture emerges. Such developmental ‘clocks’ define how plants and animal tissues organise and communicate in the overall organism. Here, researchers find similar mechanisms in an organism billions of years older. These Bacillus subtilis bacteria develop a pattern of concentric rings (artificially coloured here), each made of thousands of single bacterial cells and contributing to a thriving communal colony called a biofilm. Using a combination of mathematical modelling and experiments, researchers examine the genes helping to segment the bacteria, finding some rings serve as sites for the birth of new spores. Learning more about the underlying clock, and the evolution of development, may help in tackling stubborn biofilms in hospitals and kitchens, limiting the spread of infections.

Written by John Ankers

Image from work by Kwang-Tao Chou, Dong-yeon D.Lee and Jian-geng Chiou, and colleagues

Molecular Biology Section, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA

Image copyright held by the original authors

Research published in Cell, January 2022