Today, an international research team led by Jef Boeke of New York University Langone Medical Center and Joel Bader at Johns Hopkins University in Baltimore, Maryland, reported in Science a remarkable feat – the complete de novo synthesis and redesign of five yeast chromosomes, a first step towards a completely synthetic model eukaryote. Over at Nature News, Amy Maxmen has done an admirable job covering that achievement, part of a project called Sc2.0. What I’d like to talk about is one of the artistic flourishes used to illustrate it.
In a two-page spread on pages 1038 and 1039 of the print issue, Science offers a short introduction to the seven-paper package. In the background of that article, they present a simple rendering of the yeast genome, highlighting those chromosomes that the Sc2.0 team redesigned. The image is relatively low-resolution, with 16 pairs of blue and yellow wasp-waisted chromatids on a black background. But here’s the thing: the artist who created that picture used not oil and canvas as their medium, but yeast.
It’s a process called “YeastArt,” and here’s how it works:
In 2015, Boeke’s team described a strategy for building biosynthetic pathways in yeast. Called VEGAS (Versatile Genetic Assembly System), the method is kind of a cross between Gibson Assembly and Golden Gate cloning, and it allows researchers to synthesize biotechnologically useful molecules in yeast, an organism that is considerably more malleable than these molecules’ normal sources.
As a proof of principle, the team built strains expressing the plant pigment beta-carotene at different levels, producing a spectrum of colors from white to orange. They also created strains expressing the bacterial pigment violacein, which produces dark purple, almost jet-black yeast, and fleshed out their collection with a blue pigment from sea anemone, a light purple dye from coral, and red fluorescent protein. According to Jasmine Temple, the lab technician who created the Science image, the current palette contains 11 colors: black (dark purple), white, gray, dark orange, light orange, dark yellow, light yellow, red, pink, purple, and blue.
To create a picture, the team maps each color in the image to a corresponding strain. They then use those mappings to guide an automated acoustic liquid dispensing robot called Echo, and “print” the picture pixel by pixel by spraying nanoliter-scale inocula of yeast – what the team call ‘biopixels’ – onto an inverted agar plate. After a couple days in the incubator to allow the colonies to grow, the plate is transferred to the cold room, where the colors develop over several weeks. The maximum resolution is 192 x 128 = 24,576 biopixels per image, Temple says.
Boeke’s team has used this approach – which the lab has dubbed ‘biopointillism’ – to create Saccharomyces-laden images of Gregor Mendel, a Campbell’s soup can, and a smiling cat, among others; custom designs also are available. One image, capturing the New York City skyline at sunset, won FASEB’s 2016 BioArt competition.
Accolades are nice, but Boeke didn’t set out to be an artist. Genetic engineering, though, begat inspiration. “Once the colors appeared, it was like, we’ve got to try this,” he says.
Jeffrey Perkel is Nature‘s technology editor.