Scientists hide a real movie within a germ’s DNA | Science News for Students

Scientists hide a real movie within a germ’s DNA

A tool called CRISPR helped store a galloping horse GIF in the DNA of bacteria
Jul 31, 2017 — 7:00 am EST
horse running

Pictures by turn-of-the-century photographer Eadweard Muybridge became an animation that scientists stored in bacterial DNA.

EADWEARD MUYBRIDGE/U.S. LIBRARY OF CONGRESS

There’s a new movie that lasts only about one second and has no plot. Still, it’s generating a real buzz. That’s because scientists have stored this movie into the DNA of living bacteria.

Researchers stitched together the movie at Harvard University in Cambridge, Mass. They used a trendy tool called CRISPR (pronounced “crisper”), which edits genes. Those are the codes that direct a cell to make the proteins that do its work. The new editing tool is a molecular technology that lets scientists cut apart DNA and paste it back together — usually in a new way. This changes the code in those genes, and therefore what they do.

CRISPR has already helped researchers stop disease-carrying mosquitoes from breeding. Last year, Seth Shipman and his colleagues at Harvard recorded bits of information. Then they used CRISPR to splice it into the DNA of E. coli bacteria.

Now, this team is taking things a step further. It encoded images in bacterial DNA of a human hand, as well as of a short movie. That movie was a GIF of a galloping horse. Its five frames were images by famous turn-of-the-century photographer Eadweard Muybridge, who took pictures of animals and people in motion.

The researchers stored the moving images as nucleotides. Those are molecules within DNA that come in four types, called A, C, T and G. They’re the alphabet of DNA. And the order of those letters serves as a kind of code that holds an organism’s genetic instructions.

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horse gif
Researchers used gene-editing technology called CRISPR to encode this GIF in the DNA of E. coli bacteria. The movie has five 36-by-26-pixel frames. When the researchers decoded the images from later generations of bacteria, the movie looked almost as good. (Original image, left; image reconstructed from bacteria, right.)
SETH SHIPMAN

For their latest work, the scientists created a new code. It holds the instructions for coloring the pixels, or small squares, in the black-and-white images they wanted to store. Strings of three nucleotides stood for 21 different shades, ranging from black to white. The team encoded the video — frame by frame — in nucleotide sequences they made in the lab. Then they used CRISPR technology to paste the new sequences into the genes of E. coli bacteria.

The scientists grew the bacteria for several generations. Then they peered into the DNA of the newest bacteria. From these DNA, they were able to read, and reconstruct, the images and movie. About 90 percent of the encoded information had survived.

Shipman and his colleagues shared their results July 12 in Nature.

It’s not a perfect storage system. But the results show how CRISPR could help hide data in the genetic blueprints of bacteria. The study is part of a larger effort to use DNA to store data — from audio recordings and poetry to entire books. Maybe it could even store a recipe for some popcorn to go with that movie.

Power Words

(for more about Power Words, click here)

audio     Having to do with sound.

bacterial     Having to do with bacteria, single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside animals.

bit     (in computer science) The term is short for binary digit. It has a value of either 0 or 1.

code     (in computing) To use special language to write or revise a program that makes a computer do something.

colleague     Someone who works with another; a co-worker or team member.

CRISPR     An abbreviation — pronounced crisper — for the term “clustered regularly interspaced short palindromic repeats.” These are pieces of RNA, an information-carrying molecule. They are copied from the genetic material of viruses that infect bacteria. When a bacterium encounters a virus that it was previously exposed to, it produces an RNA copy of the CRISPR that contains that virus’ genetic information. The RNA then guides an enzyme, called Cas9, to cut up the virus and make it harmless. Scientists are now building their own versions of CRISPR RNAs. These lab-made RNAs guide the enzyme to cut specific genes in other organisms. Scientists use them, like a genetic scissors, to edit — or alter — specific genes so that they can then study how the gene works, repair damage to broken genes, insert new genes or disable harmful ones.

data     Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.

DNA     (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. It is built on a backbone of phosphorus, oxygen, and carbon atoms. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

E. coli     (short for Escherichia coli) A common bacterium that researchers often harness to study genetics. Some naturally occurring strains of this microbe cause disease, but many others do not.

gene     (adj. genetic) A segment of DNA that codes, or holds instructions, for a cell’s production of a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.

genetic     Having to do with chromosomes, DNA and the genes contained within DNA. The field of science dealing with these biological instructions is known as genetics. People who work in this field are geneticists.

GIF    (short for Graphics Interchange Format) This is a format used to send images, especially movies, on the internet. An animated GIF file is one that can move on the internet, such as a swirling flag or jumping frog.

molecule     An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

nucleotides     The four chemicals that, like rungs on a ladder, link up the two strands that make up DNA. They are: A (adenine), T (thymine), C (cytosine) and G (guanine). A links with T, and C links with G, to form DNA. In RNA, uracil takes the place of thymine.

organism     Any living thing, from elephants and plants to bacteria and other types of single-celled life.

pixel     Short for picture element . A tiny area of illumination on a computer screen, or a dot on a printed page, usually placed in an array to form a digital image. Photographs are made of thousands of pixels, each of different brightness and color, and each too small to be seen unless the image is magnified.

Citation

Journal: S.L. Shipman et al. Molecular recordings by directed CRISPR spacer acquisition. Science. June 9, 2016. doi: 10.1126/science.aaf1175