Archive for the ‘Biology’ Category

Gene editing still has a few bugs in the system

February 19th, 2019
February 7, 2019, Saxony-Anhalt, Halle (Saale): In the genetic engineering monitoring laboratory of the State Office for Environmental Protection of Saxony-Anhalt, Damaris Horn is sipping reaction preparations for the polymerase chain reaction (PCR) in a special cabin.

Enlarge / February 7, 2019, Saxony-Anhalt, Halle (Saale): In the genetic engineering monitoring laboratory of the State Office for Environmental Protection of Saxony-Anhalt, Damaris Horn is sipping reaction preparations for the polymerase chain reaction (PCR) in a special cabin. (credit: Picture Alliance | Getty Images )

Gene editing has been in the news lately due to an ethically reckless experiment in which human embryos were subjected to an inefficient form of gene editing. The subjects, now born, gained uncertain protection from HIV in exchange for a big collection of potential risks. A large number of ethicists and scientists agreed that this isn't the sort of thing we should be using gene editing for.

That response contains an implicit corollary: there are some things that might justify the use of gene editing in humans. Now, a series of papers looks at some reasonable use cases in mice and collectively finds that the technology really isn't ready for use yet.

Use cases

Gene editing will likely always come with a bit of risk; when you're cutting and pasting DNA in millions of cells, extremely rare events can't be avoided. So the ethical questions come down to how we can minimize those risks and what conditions make them worth taking.

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Posted in Biology, gene editing, Genetic diseases, Genetics, medicine, Muscular dystrophy, progeria, science | Comments (0)

Georgia Tech scientists figured out how maggots can eat so much, so fast

February 17th, 2019
Studying the collective feeding behavior of black soldier fly larvae.

Enlarge / Studying the collective feeding behavior of black soldier fly larvae. (credit: Hu lab/Georgia Tech)

How do the larvae of black soldier flies eat so much, so fast, despite their tiny size? Scientists at Georgia Tech have been studying this "collective feeding" behavior and found that one strategy for maximizing the larvae's feeding rate involves forming maggot "fountains." The scientists described the results in a recent paper in the Journal of the Royal Society Interface, along with an entertaining video showing a swarm of larvae consuming an entire pizza in just two hours.

"This is the first time, as far as I know, that we've really tried to quantify how much they were able to eat, and how they are able to do it," said graduate student and co-author Olga Shishkov, who demonstrated the research on Saturday at the American Association for the Advancement of Science meeting in Washington, DC. It's not the first time she's had fun demonstrating the maggots' hearty appetite in creative ways: last year, she videotaped the critters devouring a heart-shaped donut for Valentine's Day.

Shishkov's advisor is David Hu, who runs a biolocomotion laboratory at the Georgia Institute of Technology studying how various creatures move. He is perhaps best known for his work with fire ants, but his lab also studies cat tongues, water striders, snakes, various climbing insects, mosquitos, and, of course, black soldier fly larvae.

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Posted in Biology, collective behavior, fluid dynamics, Physics, science | Comments (0)

The replication crisis may also be a theory crisis

February 16th, 2019
A jumbled jigsaw puzzle, AKA the state of theory in the behavioral sciences.

Enlarge / A jumbled jigsaw puzzle, AKA the state of theory in the behavioral sciences. (credit: flickr user: giveawayboy)

A replication crisis has called into question results from behavioral (and other) sciences. Complaints have focused on poor statistical methods, the burying of negative results, and other “questionable research practices” that undermine the quality of individual studies.

But methods are only part of the problem, as Michael Muthukrishna and Joseph Henrich argue in a paper in Nature Human Behaviour this week. It’s not just that individual puzzle pieces are low in quality; it’s also that there’s not enough effort to fit those pieces into a coherent picture. "Without an overarching theoretical framework,” write Muthukrishna and Henrich, “empirical programs spawn and grow from personal intuitions and culturally biased folk theories.”

Doing research in a way that emphasizes joining the dots constrains the questions you can ask in your research, says Muthukrishna. Without a theoretical framework, “the number of questions that you can ask is infinite.” This makes for a scattered, disconnected body of research. It also feeds into the statistical problems that are widely considered the source of the replication crisis. Having too many questions leads to a large number of small experiments—and the researchers doing them don't always lay out a strong hypothesis and its predictions before they start gathering data.

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Posted in Behavioral science, Biology, replication crisis, science | Comments (0)

Carbon dioxide’s boost to trees may not offset its climate impact

February 3rd, 2019
Closeup image of cedar buds.

Enlarge / Buds on a cedar tree. (credit: webhamster / Flickr)

One of the dumber but more-persistent climate change memes is based around the claim that CO2 is plant food. Plants rely on it for photosynthesis, so increasing its level in the atmosphere should benefit plants by boosting their growth. There are variants on this that claim plants are currently starved for carbon dioxide, while others suggest plants will grow so fast that they'll keep the carbon from warming the atmosphere much at all.

Fortunately, if you search the Web for "carbon dioxide is plant food," all of the early hits you get are from people and organizations debunking the idea. While CO2 can help plants and may have contributed to a general greening of the Earth, it's just one of a number of factors that influence plant growth. And a new study shows that, even when trees are clearly benefitting from the rising levels of atmospheric carbon, they don't seem to be growing any faster.

Ask the trees

Carbon dioxide is incorporated into sugars through the action of a rather inefficient enzyme, so simply having more of it around makes photosynthesis run smoothly. When there's more around, the pores that allow it into leaves can also close up a bit more, which conserves water. For these reasons, carbon dioxide has a fertilizing effect on many plants.

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Posted in Biology, climate change, Earth science, science, trees | Comments (0)

Watching brains on acid using an MRI

February 1st, 2019
LSD blotter paper

Enlarge / LSD blotter paper (credit: campusdrugprevention.gov)

What exactly happens in a brain when it is hit by a hallucinogen? Lots of drugs have effects that are obvious extensions of our normal body processes; they raise moods, dull pain, or boost our energy. But hallucinogens are notable for giving their users experiences that are anything but normal.

Now, a team of Swiss researchers have used MRI imaging to follow the brain as it's under the influence of acid. And their results support the idea that hallucinogens cause the breakdown of the system that helps the brain keep track of which information is coming from the real world and which is generated by the brain itself.

Cortex overload

The brain receives a steady flow of information, some from the outside world, some from the body, and some generated by its internal thought processes. Your brain has to essentially decide which of it to take seriously and raise to the level of consciousness, which to monitor subconsciously, and which to discard. Hallucinations, whether due to drugs or mental disorders, appear to involve a breakdown in this information processing.

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Posted in Biology, drugs, fMRI, hallucinogens, Neuroscience, science | Comments (0)

New estimate of primate mutation rates helps genetics match fossils

January 25th, 2019
Carl, an alpha-male chimpanzee at Copenhagen Zoo and one of the participants in the study.

Carl, an alpha-male chimpanzee at Copenhagen Zoo and one of the participants in the study. (credit: Copenhagen Zoo, David Tr)

It’s not every day that scientists accidentally uncover a gorilla paternity scandal. But when a team of researchers led by Søren Besenbacher in Denmark went looking for genetic data on great ape families, one of their gorilla fathers “turned out to be only half as related to the child as expected,” the researchers write.

With some investigation, they discovered that the real father was in fact the 12-year-old son of the gorilla that was thought to be the dad. “This was as much a surprise to us as it was to the zoo that house[s] the gorilla father and son,” they add.

Besenbacher and his colleagues were unintentionally unearthing the dirty secrets of gorilla families because they were interested in mutation rates—how often new changes in DNA appear. Specifically, they were trying to see whether humans are the outliers among our great ape family, as we have an unusually slow rate of accumulated mutations in our genomes. In a paper published in Nature Ecology and Evolution this week, they report their results: yes, we are indeed unusual. And it’s not clear why.

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Posted in Biology, evolution, Genetics, science | Comments (0)

Hermit crabs evolved longer penises to keep their shells from being stolen

January 19th, 2019
An adult male hermit crab of the species <em>Coenobita compressus</em> ambling along on a leisurely stroll.

Enlarge / An adult male hermit crab of the species Coenobita compressus ambling along on a leisurely stroll. (credit: Mark Laidre)

Hermit crabs protect their soft, curved abdomens from harm by scavenging seashells and turning them into portable homes. That poses a challenge when it comes time to mate, since a rival can steal the shell while its occupant is, shall we say, otherwise occupied. A new paper in the journal Royal Society Interface poses an intriguing new hypothesis: some species of male hermit crabs evolved substantially longer penises so they could mate without having to venture too far outside their shells.

Mark Laidre, a biologist at Dartmouth College in New Hampshire, dubbed his hypothesis "private parts for private property." He's been studying the behavior of a particular species of hermit crab, Coenobita compressus, for the last decade.

Seashells are a valuable, limited resource—a kind of private property for hermit crabs, their most prized possession—and particularly so for Coenobita compressus. This species engages in elaborate remodeling of scavenged shells to tailor it precisely to their liking, tearing out hard material inside the shell over several months to make more room for their bodies. Because the shells are so valuable, there is stiff competition to attain a really nice shell. Fights break out, crabs will kill another crab for their shells, and sometimes they will just outright steal them. Since the remodeled shells prevent the creatures from drying out (which can happen within 24 hours), they are crucial to the crabs' survival.

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Posted in Biology, evolutionary biology, hermit crabs, reproduction, science, sex | Comments (0)

For teens, digital technology is good. Or bad. Or maybe neutral?

January 18th, 2019
For teens, digital technology is good. Or bad. Or maybe neutral?

Enlarge (credit: SimpleTexting.com)

In South Korea, people under the age of 16 can’t play online games between midnight and 6am. The UK Parliament has launched an official inquiry into “the impact of social media and screen use on young people’s health.” Meanwhile in the United States, the Wait Until 8th campaign asks parents to delay giving their children a smartphone until they’re in eighth grade. Worry about kids and technology is rampant—so have smartphones, in fact, destroyed a generation?

A paper published in Nature Human Behaviour this week answers that question, often differently, thousands and thousands of times. Researchers Amy Orben and Andrew Przybylski took three huge datasets and threw every possible meaningful question at them. In part, their analysis is an illustration of how different researchers can get wildly different answers from the same data. But cumulatively, the answers they came up with indicate that tech use correlates with a teeny-tiny dent in adolescent well-being—and that there’s a big problem with big data.

High numbers don’t necessarily mean high quality

Studying small numbers of people, or rats, or trees can be a problem for scientists. Comparisons between small groups of subjects might miss a real finding or luck out and find something that looks like a pattern but is actually just noise. And it’s always tricky to generalize from a small group to a whole population. Sometimes small is the only sort of data that’s available, but some research disciplines have had the recent(-ish) boon of gigantic, rich datasets to work with.

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Posted in Behavioral science, Biology, science, statistics | Comments (0)

It’s the drag that helps the humble hagfish slime predators so quickly

January 17th, 2019

Courtesy of University of Wisconsin, Madison.

The homely hagfish might look like just your average bottom feeder, but they have a secret weapon: they can unleash a full liter of sticky slime in less than one second. That slime can clog the gills of a predatory shark, for instance, suffocating it. Scientists are unsure just how the hagfish (affectionately known as a "snot snake") accomplishes this feat, but a new paper in the Journal of the Royal Society Interface suggests that turbulent water flow (specifically, the drag such turbulence produces) is an essential factor.

Scientists have been studying hagfish slime for years because it's such an unusual material. It's not like mucus, which dries out and hardens over time; hagfish slime stays slimy, giving it the consistency of half-solidified gelatin. That's due to long, thread-like fibers in the slime, in addition to the proteins and sugars that make up mucin, the other major component. Those fibers coil up into "skeins" that resemble balls of yarn. When the hagfish lets loose with a shot of slime, the skeins uncoil and combine with the salt water, blowing up more than 10,000 times its original size.

Yet the precise mechanism for slime deployment is still poorly understood, according to co-author Gaurav Chaudhary of the University of Illinois, Urbana-Champaign. Recent research showed that sea water is essential to the formation of the slime, and that hagfish skeins can unravel spontaneously if ions in the sea water mixes the adhesives that hold the fibrous threads together in skeins. Chaudhary says that what's missing in this earlier work is taking the fast time scales into account. A 2014 study, for instance, showed that any spontaneous unraveling of the skeins would take several minutes—yet the hagfish deploys its slime in about 0.4 seconds.

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Posted in Biology, fluid dynamics, hagfish, Physics, science, slime and mucus | Comments (0)

On GMO safety, the fiercest opponents understand the least

January 15th, 2019

Science is our most effective means of understanding the natural world, yet the public doesn't always accept the understanding that it produces. Researchers have been trying to figure out why there's a gap between science and the public for decades, an effort that is becoming increasingly relevant as the US seems to have a growing discomfort with facts in general. In some cases, the issue is clearly cultural: politics and religion appear to have strong influences on whether people accept the science on climate change and evolution, respectively.

It would be easy to think that the controversy over GMO foods is similar. After all, opposition to GMOs is often ascribed to liberal granola eaters. But several polls have suggested that's not the case, as there's as much discomfort about GMOs on the right as there is on the left. Now, a new study in Nature Human Behavior suggests an alternate explanation: opposition to GMOs is highest among those who know the least about genetics but have convinced themselves they're experts. Or as the authors put it, "Extreme opponents know the least but think they know the most."

Science literacy

A US-Canadian team of researchers started off by having a demographically diverse group of 500 US residents answer a series of questions. Participants were asked to rate their level of concern with and opposition to GMOs. As had been found in past surveys, there was a lot of uncertainty about the biotechnology; more than 90 percent of respondents reported concern, and a similar number were somewhat opposed to its use. But that opposition didn't break down along political lines: "there were no significant differences in extremity of opposition between self-reported liberals, moderates, and conservatives."

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Posted in Behavioral science, Biology, GMO foods, GMOs, Human behavior, public understanding of science, science | Comments (0)