Scientists Put a GIF Inside Living Bacteria

Researchers at Harvard University have figured out a way to embed moving images into the DNA of E. coli bacteria. The team described their process in the journal Nature.

It's a setup any spy would love: a code within a code. The paper authors see bacterial DNA as a form of information storage, almost like a computer's hard drive. As the science of gene editing technology advances, we're learning how to fit more—and more complex—information on the same equipment.

Enabling this advancement is a gene editing technique called CRISPR-Cas, which gives scientists access to certain immune-activating regions of bacterial DNA. Researchers have already used that access to engineer malaria-resistant mosquitoes and track down disease-causing pathogens. 

Other scientists have successfully inserted secret messages in E. coli's genetic blueprints. Some have even gotten the bacteria to hold pictures. But until now, none of those pictures have moved.

The Harvard team wanted to see how far CRISPR-Cas could get them. First, they had to select their images. And while some researchers may have taken this opportunity to immortalize a goofy cat GIF, the Harvard team wanted the content of the first-ever bacterial home movies to have significance.

Eadweard Muybridge was a 19th-century photographer whose work blurred the line between art and science. Muybridge pushed the camera technology of the time to its limits, using what was then high-speed imaging to capture incredible shots of people and other animals in motion. His photos showed us the potential of both cameras and our bodies.

And so the authors of the new paper thought it would be appropriate to make their first moving image a Muybridge—specifically, his groundbreaking image of a horse in full gallop. They converted the images to pixels, then converted those pixels to nucleotides, which are often called the building blocks of DNA. They popped those nucleotides into the bacteria's genetic code, then ran the DNA through a sequencer to see if the pixel information stayed in place. It did.

But lead author Seth Shipman says printing images is just the beginning. He envisions a world in which our cells work like microscopic cameras, recording the state and goings-on inside our bodies.

"What we want this system to be used for, eventually, is not to encode information that we already have, but for a way for cells to go out and gather information that we don't have access to," Shipman told Popular Science. "If we could have them collect data and then store that data in their genomes, then we might have access to completely new types of information."

If that concept sounds kind of creepy to you, we have some good news: It's still a long way off.

[h/t Popular Science]

Does Sound Travel Faster or Slower in Space?


Viktor T. Toth:

It is often said that sound doesn’t travel in space. And it is true … in empty space. Sound is pressure waves, that is, propagating changes in pressure. In the absence of pressure, there can be no pressure waves, so there is no sound.

But space is is not completely empty and not completely devoid of pressure. Hence, it carries sound. But not in a manner that would match our everyday experience.

For instance, if you were to put a speaker in interstellar space, its membrane may be moving back and forth, but it would be exceedingly rare for it to hit even a single atom or molecule. Hence, it would fail to transfer any noticeable sound energy to the thin interstellar medium. Even the somewhat denser interplanetary medium is too rarefied for sound to transfer efficiently from human scale objects; this is why astronauts cannot yell to each other during spacewalks. And just as it is impossible to transfer normal sound energy to this medium, it will also not transmit it efficiently, since its atoms and molecules are too far apart, and they just don’t bounce into each other that often. Any “normal” sound is attenuated to nothingness.

However, if you were to make your speaker a million times bigger, and let its membrane move a million times more slowly, it would be able to transfer sound energy more efficiently even to that thin medium. And that energy would propagate in the form of (tiny) changes in the (already very tiny) pressure of the interstellar medium, i.e., it would be sound.

So yes, sound can travel in the intergalactic, interstellar, interplanetary medium, and very, very low frequency sound (many octaves below anything you could possibly hear) plays an important role in the formation of structures (galaxies, solar systems). In fact, this is the mechanism through which a contracting cloud of gas can shed its excess kinetic energy and turn into something compact, such as a star.

How fast do such sounds travel, you ask? Why, there is no set speed. The general rule is that for a so-called perfect fluid (a medium that is characterized by its density and pressure, but has no viscosity or stresses) the square of the speed of sound is the ratio of the medium’s pressure to its energy density. The speed of sound, therefore, can be anything between 0 (for a pressureless medium, which does not carry sound) to the speed of light divided by the square root of three (for a very hot, so-called ultrarelativistic gas).

This post originally appeared on Quora. Click here to view.

How Fossil Fuel Use Is Making Carbon Dating Less Accurate Wedzinga Wedzinga

The scientific process of carbon dating has been used to determine the age of Ötzi the Iceman, seeds found in King Tutankhamun’s tomb, and many other archaeological finds under 60,000 years old. However, as SciShow points out in a recent episode, the excessive use of fossil fuels is making that method less reliable.

Carbon dating, also called radiocarbon or C-14 dating, involves analyzing the ratio of two isotopes of carbon: C-14 (a radioactive form of carbon that decays over time) and C-12 (a more stable form). By analyzing that ratio in a given object compared to a living organism, archaeologists, paleontologists, and other scientists can get a pretty clear idea of how old that first object is. However, as more and more fossil fuels are burned, more carbon dioxide is released into the environment. In turn, this releases more of another isotope, called C-12, which changes the ratio of carbon isotopes in the atmosphere and skews the carbon dating analysis. This phenomenon is called the Suess effect, and it’s been well-documented since the ‘70s. SciShow notes that the atmospheric carbon ratio has changed in the past, but it wasn’t anything drastic.

A recent study published in Nature Communications demonstrates the concept. Writing in The Conversation, the study authors suggest that volcanoes “can lie about their age." Ancient volcanic eruptions can be dated by comparing the “wiggly trace” of C-14 found in trees killed in the eruption to the reference "wiggle" of C-14 in the atmosphere. (This process is actually called wiggle-match dating.) But this method “is not valid if carbon dioxide gas from the volcano is affecting a tree’s version of the wiggle,” researchers write.

According to another paper cited by SciShow, we're adding so much C-12 to the atmosphere at the current rate of fossil fuel usage that by 2050 brand-new materials will seem like they're 1000 years old. Some scientists have suggested that levels of C-13 (a more stable isotope) be taken into account while doing carbon dating, but that’s only a stopgap measure. The real challenge will be to reduce our dependence on fossil fuels.

For more on how radiocarbon dating is becoming less predictable, check out SciShow’s video below.