“Earth-like planets in the habitable zone — the region around a star where temperatures could allow liquid water to exist — can easily be up to a billion times dimmer than their host star,” said research team leader Nico Deshler from the University of Arizona. “This makes them difficult to detect because their faint light is overwhelmed by the star’s brightness. Our new coronagraph design siphons away starlight that might obscure exoplanet light before capturing an image.”

In Optica, the researchers show that the new coronagraph can theoretically achieve the fundamental limits of exoplanet detection and localization set by quantum optics. They also used it to capture images that allowed them to estimate the position of artificial exoplanets with distances from their host star up to 50 times smaller than what the telescope’s resolution limit would normally allow.

“Compared to other coronagraph designs, ours promises to supply more information about so-called sub-diffraction exoplanets — those which lie below the resolution limits of the telescope,” said Deshler. “This could allow us to potentially detect biosignatures and discover the presence of life among the stars.”

Blinded by the light

Optically analyzing exoplanets poses a formidable challenge because, at astronomical scales, they are often too close to their parent star for current telescopes to resolve. Exoplanets can also be orders of magnitude dimmer than their host star. Although astronomers have developed various ways to indirectly infer the presence of a planet around a prospective star, directly observing exoplanets in images would be ideal.

With NASA’s next-generation space telescope, the Habitable Worlds Observatory (HWO), being dedicated to exoplanet science, many coronagraph designs have emerged, each with different practical and theoretical performance trade-offs. At the same time, recent work has shown that traditional notions of resolution for telescopes do not reflect fundamental limits and can be circumvented with careful optical pre-processing.

Inspired by these developments, the researchers decided to use a spatial mode sorter available in their lab to develop an improved coronagraph that theoretically rejects all the light from an on-axis star while achieving maximal throughput of an off-axis exoplanet.

Much like piano notes emit different acoustic frequencies, light sources in space excite different spatial modes — unique shapes and patterns of oscillation — depending on their position. The researchers separated these different modes using a mode sorter to isolate and eliminate light from a star and an inverse mode sorter to recompose the optical field after the starlight is rejected. This made it possible to capture an image of the exoplanet without the star.

“Our coronagraph directly captures an image of the exoplanet, as opposed to measuring only the quantity of light from the exoplanet without any spatial orientation,” said Deshler. “Images can provide context and composition information that can be used to determine exoplanet orbits and identify other objects that scatter light from a star such as exozodiacal dust clouds.”

Imaging faint exoplanets

After configuring their coronagraph in the lab, the researchers constructed an artificial star-exoplanet scene in which the exoplanet was positioned close enough to the star to be unresolvable with a traditional telescope. The contrast ratio between the star and the planet was set to 1000:1.

The researchers scanned the position of the exoplanet to simulate an orbit where the planet traverses in front of the star and then tried to determine its position in each frame. The images captured with their experimental setup incorporating the new coronagraph allowed them to estimate the position of the exoplanet at sub-diffraction planet-star separations.

The researchers are working to improve the mode sorter to reduce crosstalk, a type of interference in which light leaks across different optical modes. For scenes with moderate contrast levels, crosstalk is not very problematic. However, the extreme contrasts found in exoplanet science would require a very high-fidelity spatial mode sorter to sufficiently isolate light from the star.

The researchers say that this proof-of-principle experiment could inspire further exploration of optical pre-processing with spatial mode sorters in future astronomical instrumentation. For example, the spatial mode filtering methods they used could address more complex scenarios, such as treating stars as extended objects, and may also lead to new imaging methods for quantum sensing, medical imaging and communications.

Scientists at the Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, have worked out the structure of this machine and shown how it operates like the lock on a canal to transport pyruvate — a molecule generated in the body from the breakdown of sugars — into our mitochondria.

Known as the mitochondrial pyruvate carrier, this molecular machine was first proposed to exist in 1971, but it has taken until now for scientists to visualise its structure at the atomic scale using cryo-electron microscopy, a technique used to magnify an image of an object to around 165,000 times its real size. Details are published today in Science Advances.

Dr Sotiria Tavoulari, a Senior Research Associate from the University of Cambridge, who first determined the composition of this molecular machine, said: “Sugars in our diet provide energy for our bodies to function. When they are broken down inside our cells they produce pyruvate, but to get the most out of this molecule it needs to be transferred inside the cell’s powerhouses, the mitochondria. There, it helps increase 15-fold the energy produced in the form of the cellular fuel ATP.”

Maximilian Sichrovsky, a PhD student at Hughes Hall and joint first author of the study, said: “Getting pyruvate into our mitochondria sounds straightforward, but until now we haven’t been able to understand the mechanism of how this process occurs. Using state-of-the-art cryo-electron microscopy, we’ve been able to show not only what this transporter looks like, but exactly how it works. It’s an extremely important process, and understanding it could lead to new treatments for a range of different conditions.”

Mitochondria are surrounded by two membranes. The outer one is porous, and pyruvate can easily pass through, but the inner membrane is impermeable to pyruvate. To transport pyruvate into the mitochondrion, first an outer ‘gate’ of the carrier opens, allowing pyruvate to enter the carrier. This gate then closes, and the inner gate opens, allowing the molecule to pass through into the mitochondrion.

“It works like the locks on a canal but on the molecular scale,” said Professor Edmund Kunji from the MRC Mitochondrial Biology Unit, and a Fellow at Trinity Hall, Cambridge. “There, a gate opens at one end, allowing the boat to enter. It then closes and the gate at the opposite end opens to allow the boat smooth transit through.”

Because of its central role in controlling the way mitochondria operate to produce energy, this carrier is now recognised as a promising drug target for a range of conditions, including diabetes, fatty liver disease, Parkinson’s disease, specific cancers, and even hair loss.

Pyruvate is not the only energy source available to us. Our cells can also take their energy from fats stored in the body or from amino acids in proteins. Blocking the pyruvate carrier would force the body to look elsewhere for its fuel — creating opportunities to treat a number of diseases. In fatty liver disease, for example, blocking access to pyruvate entry into mitochondria could encourage the body to use potentially dangerous fat that has been stored in liver cells.

Likewise, there are certain tumour cells that rely on pyruvate metabolism, such as in some types of prostate cancer. These cancers tend to be very ‘hungry’, producing excess pyruvate transport carriers to ensure they can feed more. Blocking the carrier could then starve these cancer cells of the energy they need to survive, killing them.

Previous studies have also suggested that inhibiting the mitochondrial pyruvate carrier may reverse hair loss. Activation of human follicle cells, which are responsible for hair growth, relies on metabolism and, in particular, the generation of lactate. When the mitochondrial pyruvate carrier is blocked from entering the mitochondria in these cells, it is instead converted to lactate.

Professor Kunji said: “Drugs inhibiting the function of the carrier can remodel how mitochondria work, which can be beneficial in certain conditions. Electron microscopy allows us to visualise exactly how these drugs bind inside the carrier to jam it — a spanner in the works, you could say. This creates new opportunities for structure-based drug design in order to develop better, more targeted drugs. This will be a real game changer.”

The research was supported by the Medical Research Council and was a collaboration with the groups of Professors Vanessa Leone at the Medical College of Wisconsin, Lucy Forrest at the National Institutes of Health, and Jan Steyaert at the Free University of Brussels.

It depends, of course, on whether you’re making a hearty winter stew or getting ready to watch the Super Bowl.

Most scientists agree that categorizing an object — like thinking of a carrot as either a root vegetable or a party snack — is the job of the prefrontal cortex, the brain region responsible for reasoning and other high-level functions that make us smart and social. In that account, the eyes and visual regions of the brain are kind of like a security camera collecting data and processing it in a standardized way before passing it off for analysis.

However, a new study led by biomedical engineer and neuroscientist Nuttida Rungratsameetaweemana, an assistant professor at Columbia Engineering, shows that the brain’s visual regions play an active role in making sense of information. Crucially, the way it interprets the information depends on what the rest of the brain is working on.

If it’s Super Bowl Sunday, the visual system sees those carrots on a veggie tray before the prefrontal cortex knows they exist.

Published April 11 in Nature Communications, the study provides some of the clearest evidence yet that early sensory systems play a role in decision-making — and that they adapt in real-time. It also points to new approaches for designing AI systems that can adapt to new or unexpected situations.

Chromosomal rearrangements where large chunks of chromosomes are inverted, moved, deleted or duplicated, provide a possible source for such large-scale “macromutations.” However, characterizing chromosomal rearrangements with commonly tried DNA sequencing methods has been difficult.

Many organisms, including humans, are diploid, meaning they have two sets of chromosomes — one from each parent. The same is true for stick insects. This makes identifying chromosomal rearrangements with species challenging when assembling genomes.

“In the past, we’ve averaged data from each chromosome set, but the limited accuracy of this method doesn’t tell the whole story,” says Utah State University evolutionary biologist Zachariah Gompert. “Using newer, molecular and computational approaches that generate phased genome assemblies, where the two copies of each chromosome are assembled separately, has enabled us to directly show how complex chromosomal rearrangements have allowed stick insects to adapt by being cryptic on different host plants and thereby avoid predation.”

In the April 18, 2025 online issue of the American Association for the Advancement of Science journal Science, Gompert and colleagues report adaptive divergence in cryptic color pattern is underlain by two distinct, complex chromosomal rearrangements, where millions of bases of DNA were flipped backwards and moved from one part of a chromosome to another, independently in populations of stick insects on different mountains. Contributing authors on the paper include Gompert’s long-time collaborator Patrik Nosil and other researchers from the French National Center for Scientific Research (CNRS), along with scientists from the University of Notre Dame, the University of Nevada, Reno, and The Institute of Cancer Research in the United Kingdom. The research is supported by the National Science Foundation and the European Research Council.

The scientists studied Timema cristinae insects with varied color patterns, collected from two mountains near Santa Barbara, California. The wingless, plant-feeding insects are divergently adapted to two different plant species in the coastal chaparral habitats. One stick insect pattern is green, allowing it to blend in with the California lilac, while the other sports a thin, white stripe on its back making it nearly undetectable among the needle-like leaves of the chamise shrub.

Gompert and colleagues showed this adaptive difference in color pattern is almost completely explained by the presence versus absence of these individual complex, chromosomal rearrangements.

“The new phased genomic assembly technology used in this study was a critical piece in helping us examine how color pattern evolved in these insects,” says Gompert, professor in USU’s Department of Biology and the USU Ecology Center. “Our findings suggest chromosomal rearrangements might be more widespread and more complex than we previously thought.”

He says these mutations, despite being large, are easy to miss using traditional DNA sequencing approaches.

“Chromosomal rearrangements can be difficult to detect and characterize using standard approaches,” Gompert says. “We’re essentially exploring the ‘dark matter’ of the genome.”

Structural variation, he says, rather than being rare, may be regularly available to prompt evolution.

“We’re just scratching the surface,” Gompert says. “We’ve lacked the tools to detect structural variation, but with improved technology we hypothesize it plays a more important role in evolution than previously recognized.”