Like the other fish, but with a battery and no taste for worms
News and notes about science
Allow me to introduce Sofi — like “Sophie,” but short for “Soft Robotic Fish,” revealed recently in Science Robotics, by scientists at the Massachusetts Institute of Technology Computer Science and Artificial Intelligence Lab.
They explained how their finned robot was created and how her first ocean swim on a coral reef outside of Fiji went. Robotic fish like her could be essential to understanding and protecting marine life in danger of disappearing in a fragile ocean environment, threatened by human activity and climate change.
This foot-and-a-half long robot mimics a real fish. She can swim in the ocean at speeds up to half-its-body-length a second and at depths up to 60 feet below the surface. Sofi has a battery that will last 45 minutes before she shuts down.
Although critical for studying the ocean, remote operated vehicles and submersibles can be expensive to build and operate. Sleek, untethered, relatively inexpensive and well-tolerated, Sofi may provide biologists a fish’s-eye view of animal interactions in changing marine ecosystems.
For this group of MIT roboticists, Sofi was a dream, combining their love of diving with their work on soft robots. She was also an engineering challenge.
The communication system was the biggest challenge, said Robert Katzschmann, a graduate student at MIT who led the team, because normally it requires a cable. Common remote signals used for piloting aerial drones don’t travel below water.
But sound waves do.
They built their own language, sending coded messages on highpitched sound waves between Sofi and the diver. Different bits of information were assigned their own tones. A processing system decoded and relayed the messages to tell the diver things like “Sofi is currently swimming forward” or command her to “turn left, 20 degrees.”
The high-pitched signals only travel about 65 feet and are inaudible to fish.
“Our primary goal was to make something for biologists,” said Katzschmann, who envisions a future network of sensor-clad Sofis for studying schooling dynamics or monitoring pollution over time.
— Joanna Klein
Bald eagle count finds two not yet airworthy
The bone-cold rain didn’t keep the regulars from rising early on a Saturday, braving winding mountain roads and thick fog, to wade through muddy lake beds, binoculars in-hand, searching.
About 150 Southern Californians showed up to count bald eagles at six inland lakes, part of a little-known federal program that’s been running for 39 years.
“The level of interest is really extraordinary,” said Ann Bowers, a wildlife biologist at the U.S. Forest Service who has been leading the count for the past three years.
“These eagles are more than just a symbol,” she added. “They’re very faithful to their territories, they’re monogamous, they experience the same kind of challenges that we do in some ways.”
At this time of year, bald eagles are settling in at lakes like this one across the region. The eagles, which mate for life, are primarily fishers.
Visitors at six lakes in the San Bernardino National Forest and two California state parks come with notebooks, cameras and spotting scopes. The forest service keeps the public about a quarter-mile away from nesting sites; land adjacent is closed off, so that eagles won’t feel threatened and abandon their young.
This year, 15 bald eagles were spotted: 10 adults, three juveniles and two chicks, month-old youngsters who hatched live on a webcam in February. While 15 eagles may not sound like a lot, this species has been a surprising conservation success in a state suffering droughts and sprawling metropolises.
Fifteen years ago, most bald eagles were winter residents, arriving inland during the January through August mating seasons, eagles follow the paths of migratory waterfowl.
But lately, eagle numbers are a bit down. “In a typical winter, I usually see three to four eagles between my house and work,” said Robin Eliason, the forest service biologist who has led the overall program since 1989. But lately, “I haven’t seen any of those eagles.”
The decline could be due to warmer winters, she added. Eagles find more prey on these lakes when it’s colder.
— Adam Popescu
Something’s brewing in the lab: Beer without hops
If Americans will eat a burger with no meat, will they drink a beer without hops?
Charles Denby, a biochemist at the University of California, Berkeley, might have made it an option. Denby works in a lab that focuses on creating sustainable fuel out of plant molecules called terpenes. But he is also “a very enthusiastic home brewer,” he said. When he learned that some terpenes could, in small doses, impart the taste of hops — the small, green flowers that give beer its bitter, citrusy flavor — he decided to perform a side experiment.
Denby and his colleagues infused brewer’s yeast with DNA from basil and mint, two plants that naturally produce the hop-flavored terpenes. The scientists were aiming to re-create the flavor of Cascade hops, which are most popular among craft brewers. They used the engineered yeast to brew a hops-free ale.
There were some misfires. “The real challenge of the study was to produce strains that produce flavor molecules at the right concentrations without sacrificing other aspects of the brewing yeast performance,” Denby said.
Once they perfected the formula, the tasting began.
“To me, it tasted distinctively hoppy, and not unlike a beer hopped with Cascade,” Denby said.
Wanting a more objective analysis, the researchers asked Lagunitas Brewing Co. in California to help them convene a double-blind taste test involving 40 participants. When asked to compare the brew’s hoppiness relative to traditionally brewed beers, the participants placed it above most of the competition.
“We were really excited to see that some of our strains produced flavors that were hoppier than conventionally dry-hopped beers,” Denby said.
The findings, published recently in Nature Communications, could contribute to a more sustainable future for beer production.
Hops are a resource-intensive crop, requiring large amounts of water and sunlight to grow. The irrigation of hops in the United States alone requires more than 260 million gallons of water a year.
Farmers can’t keep up, and brewers are facing a hops shortage that some say is slowing the growth of the craft beer industry.
Denby’s process, which he is hoping to commercialize, is a long way from putting hops farmers out of business. Still, he said, the technique could also help brewers produce a more consistent product.
— Douglas Quenqua
In the cockroach genome, ‘little mighty’ secrets
The American cockroach is the largest common house cockroach, about the length of a AA battery. Also called the water bug, it can live for a week without its head. It eats just about anything, including feces, the glue on book bindings, and other cockroaches, dead or alive. It can fly short distances and run as fast as the human equivalent of 210 mph, relative to its size.
All these feats and more are encoded in the American cockroach’s genome, its complete set of genetic instructions,which was sequenced by Chinese scientists and published recently in Nature Communications. It is the second-largest insect genome ever sequenced (the first belonging to a species of locust), and larger even than the human genome.
In China, the cockroach is often called “xiao qiang,” meaning “little mighty,” said Sheng Li, an entomology professor at South China Normal University in Guangzhou and lead author of the paper. “It’s a tiny pest, but has very strong vitality.”
His team found that groups of genes associated with sensory perception, detoxification, the immune system, growth and reproduction were all enlarged in the American cockroach, likely underpinning its scrappiness and ability to adapt to human environments.
Their study comes on the heels of the sequencing of the German cockroach genome, which was published in Nature Ecology & Evolution last month. While the German cockroach only inhabits human environments (particularly kitchens), the American cockroach flourishes in a wide range of habitats.
Both species, however, succeed worldwide as omnivorous scavengers, and are notoriously adept at dealing with insecticides and other pest control methods.
In the American cockroach, Li and collaborators annotated thousands of genes, including more than 1,000 thought to help the insect detect chemical cues from the environment. Among these are more than 300 genes associated with perceiving bitter tastes, which could help them decide which foods are safe.
The scientists also interfered with more than 20 genes thought to be related to immunity, reproduction and development, and found that doing so had damaging effects on the cockroaches.
Genes such as these are promising targets for future pest control methods, said Xavier Bellés, a research professor at the Institute of Evolutionary Biology in Barcelona.
— Steph Yin