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Winged robot demystifies insect flight

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Animated sequence of the simulation of a fruit fly moving its wings. The insect’s grey polygon body remains static while the wings, one coloured red, the other blue, move up and down.

The insect wing hinge is one of the most sophisticated skeletal structures in the animal kingdom. (Johan M. Melis et al/Nature)

A machine-learning model that can fly like a fly helped researchers to unravel the workings of the insect wing hinge. Most hypotheses about this complex biomechanical structure have been built on how it looks when it isn’t moving. An AI system, trained on video recordings of around 70,000 fruit-fly wing beats, predicted how muscle contractions would cause different wing motions. A winged robot programmed with the model’s findings then allowed the researchers to create a map linking muscle activity to flight forces.

Nature | 5 min video

Reference: Nature paper

An AI tool could help to identify the origins of cancers that have spread from a previously undetected tumour somewhere else in the body. The proof-of-concept model analyses images of cells from the metastatic cancer to spot similarities with its source — for example, breast cancer cells that migrate to the lungs still look like breast cancer cells. In dry runs, there was a 99% chance that the correct source was included in the model’s top three predictions. A top-three list could reduce the need for invasive medical tests and help clinicians tailor treatments to suit.

Nature | 4 min read

Reference: Nature Medicine paper

An initiative called ChatGPT and Artificial Intelligence Natural Large Language Models for Accountable Reporting and Use (CANGARU) is consulting with researchers and major publishers to create comprehensive guidelines for AI use in scientific papers. Some journals have introduced piecemeal AI rules, but “a standardized guideline is both necessary and urgent”, says philosopher Tanya De Villiers-Botha. CANGARU hopes to release their standards, including a list of prohibited uses and disclosure rules, by August and update them every year.

Science | 5 min read

Infographic of the week

An infographic showing how the metafluid (a blue liquid with floating yellow spheres) reacts to being compressed in a cylindrical container. In the compressed metafluid, the hollow yellow spheres collapse, taking on a floppy shape.

This ‘metafluid’ can be used to build robotic grippers that can grasp objects as large and heavy as a glass bottle — or as small and fragile as an egg. Unlike a regular liquid, the metafluid can be compressed: the small gas-filled capsules collapse when pressure increases. The pressure inside the material then plateaus for some time even if outside pressure increases further. This means that when the system is used to operate a gripper, applying the same pressure will grasp objects of various sizes and fragility. (Nature | 7 min read, Nature paywall)

Reference: Nature Reviews Materials paper

Features & opinion

AI systems could reveal hidden features in medical scans that currently require injecting dyes into the body. Contrast agents — gadolinium for magnetic resonance imaging, for example — are generally safe, but aren’t suitable for people with certain conditions. AI-assisted virtual dyes also make images taken with a fluorescence microscope appear as if they had been stained by a pathologist, a process that makes features stand out. Radiologist Kim Sandler expects to spend less time writing reports about what she sees in scans, and more time vetting AI-generated reports. “My hope is that it will make us better and more efficient, and that it’ll make patient care better,” Sandler says.

Nature | 10 min read

This article is part of Nature Outlook: Medical diagnostics, an editorially independent supplement produced with financial support from Seegene.

If neural networks mull over their training data for too long, they end up memorizing the information and become worse at adapting to unseen test data. But when researchers accidentally overtrained a model that specialized in certain mathematical operations, they discovered that it could suddenly master any test data. This ability, called ‘grokking’ — slang for total understanding — seems to happen when the system develops a unique way to solve problems. It’s not yet clear if this phenomenon applies to AI models beyond small, specialized ones. “These weird [artificial] brains work differently from our own,” says AI researcher Neel Nanda. “We need to learn to think how a neural network thinks.”

Quanta Magazine | 8 min read

When a study that pitted 256 humans against three chatbots, the AI systems were generally more creative at coming up with uncommon uses for everyday objects. The study adds to an ongoing debate about how machines master skills traditionally considered to be exclusive to people. Passing tests designed for humans doesn’t demonstrate that machines are capable of anything approaching original thought, AI researcher Ryan Burnell points out. Chatbots are fed vast amounts of mostly unknown data and might just draw on things seen in their training data, he suggests.

MIT Technology Review | 5 min read

Reference: Scientific Reports paper

Quote of the day

Chatbots are designed to identify the quickest way to an answer, even if that means jumping to conclusions or making up things, says machine-intelligence researcher Arseny Moskvichev, who teaches AI systems to read novels like most humans do: from beginning to end. (Nautilus | 6 min read)

Today, I’m bidding farewell to Boston Dynamic’s iconic humanoid robot Atlas, which is being decommissioned after 11 years of running, jumping, flips and falls. The hydraulic machine will be replaced by a new electric Atlas model with a fully rotating ‘head’ and reversible ‘hips’ that allow it to easily get up from the ground.

Please tell me about your favourite robot (real or fictional) by sending an e-mail to [email protected].Thanks for reading,

Katrina Krämer, associate editor, Nature Briefing

With contributions by Flora Graham

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Politics

How does a virus hijack insect sperm to control disease vectors and pests?

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A widespread bacteria called Wolbachia and a virus that it carries can cause sterility in male insects by hijacking their sperm, preventing them from fertilizing eggs of females that do not have the same combination of bacteria and virus. A new study led by microbiome researchers at Penn State has uncovered how this microbial combination manipulates sperm, which could lead to refined techniques to control populations of agricultural pests and insects that carry diseases like Zika and dengue to humans.

The study is published in the March 8 issue of the journal Science.

“Wolbachia is the most widespread bacteria in animals and lives symbiotically within the reproductive tissues of about 50% of insect species, including some mosquitos and flies,” said Seth Bordenstein, professor of biology and entomology, director of the One Health Microbiome Center at Penn State, and one of the leaders of the research team. “Wolbachia has genes from a virus called prophage WO integrated into its genome. These genes — cifA and cifB — allow the bacteria to remarkably manipulate sperm and quickly spread through an insect population for their own good.”

When a male and female insect that both have Wolbachia mate, they successfully reproduce and pass on the bacteria. But when a male with Wolbachia mates with a female with no Wolbachia, the sperm are rendered lethal to the fertilized eggs, succumbing them to death. This system cunningly increases the proportion of offspring with Wolbachia and the virus in the next generation, because females with the bacteria successfully reproduce more frequently than females without.

This system is being used in several ongoing pilot studies across the world to control insect pests and the harmful viral diseases they carry. For example, to control a population of agricultural or human pests that do not have the bacteria, scientists release males with Wolbachia in order to crash the population.

“One of Wolbachia’s superpowers is that it blocks pathogenic RNA viruses such as Zika, dengue and chikungunya virus, so mosquitos with Wolbachia do not pass these viruses on to people when they bite,” Bordenstein said. “So, releases of both male and female mosquitos with Wolbachia in an area where it isn’t already present leads to replacement of the population with mosquitos that can no longer pass on a viral disease. The World Mosquito Program is now using Wolbachia to control viruses in 11 countries. With this study, we reveal the underlying mechanics of how this process works so we can fine-tune the technique to expand its scope in vector control measures.”

Wolbachia’s prophage WO genes code for proteins that interfere with normal development of sperm cells. These proteins impact a critical transformation during sperm development, when the sperm’s genome is repackaged and the sperm changes from a canoe-shape into a more refined needle-like shape.

“This shape change is incredibly important to the success of sperm, and any interference can impact the sperm’s ability to travel in the female reproductive tract and successfully fertilize the egg,” said Rupinder Kaur, assistant research professor of biology and entomology at Penn State and the other leader of the research team. “The transition is highly conserved in almost everything from insects to humans. Defects in this process can also cause male sterility in humans.”

According to the researchers, sperm is particularly prone to DNA damage and repair during this transition. In this study, they found that sperm exposed to Wolbachia, or the Cif proteins alone, had an elevated level of DNA damage at this stage. The DNA damage, if not repaired in a timely fashion, can result in abnormal sperm genome packaging, male infertility and embryonic inviability.

“These results confirmed the impact of Wolbachia and Cif proteins at this stage of sperm development, but we still wanted to know what was happening at earlier stages to trigger these changes,” Kaur said. “We conducted a series of tests to explore the structure and biochemical function of the Cif proteins and found that they can cleave messenger molecules called long non-coding RNA, which sets the stage to interfere with downstream development and function of the sperm.”

The researchers used fruit flies with Wolbachia to test the potential link between the bacteria and long non-coding RNA. They found that Wolbachia — or the Cif proteins alone — reduced the amount of these RNAs. Additionally, mutant flies with reduced expression of these RNAs in conjunction with Wolbachia had elevated levels of embryonic inviability because it augmented the defective transition process of sperm development. So, Kaur explained, the virus proteins control sperm by depleting the long non-coding RNAs required for a normal sperm function.

“Long non-coding RNAs do not make any proteins themselves, but they can have profound impacts on regulating the function of other genes required for sperm development,” Bordenstein said. “By altering this non-coding part of the genome, we found that Cif proteins start impacting sperm right from the earliest stages of development. Wolbachia’s prophage WO genes act like master puppeteers, manipulating sperm development in a way that allows their genes and the symbiotic bacteria to quickly spread through arthropod populations.”

Because the process of sperm development looks similar across the animal kingdom, the researchers said that knowledge of this process could lend insight into sterility challenges in humans as well as inform new control methods of harmful insect populations.

“Now that we have reverse engineered this process, we can fine tune methods of population control with Wolbachia that are already in use,” Kaur said. “We plan to take advantage of this knowledge to augment currently existing disease vector and pest control methods, and perhaps emulate the technique without Wolbachia or virus proteins in the long-term.”

In addition to Bordenstein and Kaur, the research team includes Angelina McGarry, research technologist II at Penn State; J. Dylan Shropshire, assistant professor at Lehigh University; and Brittany Leigh, a postdoctoral researcher at Vanderbilt University at the time of the research.

Funding from the National Institutes of Health, the U.S. National Science Foundation and Penn State supported this research.

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