This Week in Science: Orangutan paintings, engineered bacteria kills tumors, biodegradable glitter

Researchers analyzed several hundred drawings made by 5 orangutans in a Japanese zoo.

Bananas about art: Environmental factors, age affect orangutan drawings

A recent study analyzed drawings done by five orangutans in a Japanese zoo and found that the drawings — especially those of one orangutan, Molly — correlate with environmental factors like seasons, daily life events and even changes in keeper identity. In total, 790 orangutan drawings were studied, 656 of which were chosen randomly from those done by Molly. Researchers found differences in color preferences that related to the current season; the orangutans tended to use purple in the spring and green in the summer and winter. In addition, Molly used more red in her drawings when another orangutan in a separate location was giving birth. The content and patterns of the drawings also changed in relation to more mundane, daily events in Molly’s life. These included new art supplies on one day, when an elementary school class visited on another and the change of her keeper once over the course of the experiment.

Orangutans share 97% common genetic heritage with humans. Compared to other primates, they have a certain level of high motor control, making them ideal candidates to study similar human behaviors. The researchers believe their findings can also be applied to humans to determine how humans’ artistic abilities can be influenced by their state of mind, as well as how external events impact internal thoughts or feelings. Molly’s drawings show that, like humans, other primates have the ability to engage in pleasant activities or enjoyable play without motivation for reward.

— Sarah Sandlow

Microscopic armies of explosive bacteria wage war on cancer

While it sounds like something straight out of a sci-fi movie, researchers recently engineered bacteria that target tumors and can act as cellular dynamite — exploding and destroying cancerous cells on command.

If these engineered bacteria are the TNT, then their gunpowder would be protein-encased pockets of air, called gas vesicles. Naturally produced and released by these cells, gas vesicles can be induced to burst when exposed to soundwaves of a certain frequency. Additionally, the researchers added proteins to the surfaces of the gas vesicles that allowed them to identify and bind to cancerous cells, using the body’s natural immune response. As a result, when a tumor-filled area of the body containing these bacteria is subjected to intense ultrasound waves, the vesicles burst and cause an implosion powerful enough to break up the tumors.

In their trials, the researchers compared the engineered bacteria treatment with new cancer drugs, called immune checkpoint inhibitors, that allow a patient’s immune system to naturally target and destroy cancer. The two treatments were given to mice with tumors, which are often used as model organisms in cancer research. The researchers observed that the mice who received the engineered bacteria lived twice as long as the mice who were given immune checkpoint inhibitors, further demonstrating the efficacy of this new technology as a way of treating cancer. Though they likely won’t become common practice anytime soon, synthetic biology techniques may present an interesting opportunity as modern medicine looks to cure diseases as old as humanity itself.

— Chris Tomo

All that glitters is not gold

Researchers recently used cellulose extracted from wood pulp to create a nontoxic, biodegradable glitter that has potential applications in the cosmetics industry. This new glitter, derived from the same substance that makes up the cell walls of plants, could one day replace existing commercial products. Many current glitters contain either microplastics or mica, a mineral often mined under unethical labor conditions. The cellulose glitter is comparable to traditional glitters in the shine and longevity of its iridescence, according to a study published on Nov. 11 in “Nature Materials.”

To produce the glitter, the scientists spread nanocrystals of cellulose into a thin, meters-long film. Once prepared, the sheets were ground into tiny particles. Due to how they bend and reflect light, the cellulose nanocrystals appear sparkly without the addition of any dyes, a phenomenon known as structural color. Manufacturing the cellulose glitter is also less energy-intensive than conventional fabrication methods, as traditional glitters get their iridescence from mineral coatings that often have to be heated at temperatures up to 800 degrees Celsius.

Prior experiments produced iridescent cellulose films in small-scale petri dishes, but this is the first time the process has succeeded at an industrial scale. The researchers intend to refine the manufacturing process and make their eco-friendly glitter available for purchase in the future.

— Rachel Liu


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