“ROS play an important role in healthy and diseased cells, but pathways that sense and control cellular ROS levels are not well understood,” said corresponding author Liron Bar-Peled, PhD, of the Krantz Family Center for Cancer Research at Mass General Cancer Center (MGCC), a member of the Mass General Brigham healthcare system. “A clearer understanding of ROS could help us understand why chemoresistance occurs in some cases.”

Low concentrations of ROS are required for normal cell signaling, but higher levels of ROS can damage cells and contribute to diseases such as cancer and neurodegeneration. Researchers know that mitochondria play an important role in ROS production, but it has been unclear if ROS-sensing proteins influence the mitochondria. If they do, this could impact responses to some anti-cancer treatments.

To investigate, co-first authors Junbing Zhang, PhD, Yousuf Ali, PhD, and Harrison Chong, of the Krantz Family Center for Cancer Research, and colleagues screened cancer cells for ROS-sensing proteins that might contribute to chemoresistance. The screen identified mutations that increased treatment resistance, and the team traced two of them to a protein called VPS35. Through further studies, they found that these mutations led to lowered ROS levels within the cell.

In addition, the investigators analyzed VPS35 expression levels in 24 patients with high grade serous ovarian cancer (HGSOC), who received treatment at MGCC. They noted that higher tumoral VPS35 levels were associated with improved treatment responses and with overall survival rates.

“We will be able to understand how water moves in and out of Greenland in the next few years,” said first author Kevin Rozmiarek, a doctoral student at the Institute of Arctic and Alpine Research (INSTAAR) at CU Boulder. “As a major freshwater reservoir, we need to understand how Greenland’s environment is going to change in the future.”

The findings were published March 14 in JGR Atmospheres.

According to the National Oceanic and Atmospheric Administration (NOAA), Greenland lost about 55 gigatons of ice and snow between fall 2023 and fall 2024. The island is shedding ice for the 28th year in a row, and scientists estimate that it has lost more than 5 trillion tons of ice since 1992.

The Greenland ice sheet contains about 8% of the planet’s freshwater, and its meltwater could contribute significantly to rising sea levels, changing ocean circulation and ecosystems worldwide.

The majority of ice loss comes from large ice chunks breaking off from glaciers and the melting of surface ice and snow. Sublimation, the process of solids turning into gases without turning into liquids first, may also play a role. Prior studies have suggested that in some parts of Greenland, about 30% of summer surface snow could sublimate to water vapor.

Tracking water in the sky

It is unclear where the water vapor goes, said Rozmiarek. Some might fall back down as snow or recondense on the surface later, but some could leave Greenland’s water system entirely.

Collecting air samples in the Arctic is an expensive and technically challenging task, because it traditionally involves flying a plane to the middle of an ice sheet in harsh weather and carrying air samples back to the laboratory.

Rozmiarek and his team overcame the challenges by loading air sampling equipment on a large drone with a 10-foot wingspan.

Throughout the summer of 2022, the team flew the drone 104 times from the East Greenland Ice-Core Project camp — managed by the University of Copenhagen — in the island’s interior. The drone collected air samples at different heights of up to nearly 5,000 feet above the ground.

The team aimed to look into the type of hydrogen and oxygen atoms in the air’s water vapor. Water molecules from different sources contain distinct combinations of hydrogen and oxygen. Scientists call these variations in isotopes.

“Isotopes are water’s fingerprints. By following these fingerprints, we can trace back to the source where the water vapor came from,” Rozmiarek said. Scientists have collected high-quality data on the source of water in Greenland, including water that flows from the tropics, and the sink, which is the surface snow on the Greenland ice sheet. “But we don’t know much about the isotopic composition of water in motion, which is the vapor between the source and sink,” he added.

When the team compared their drone-based measurements with an existing computer simulation that models the Arctic water cycle, they found the simulation underestimated the amount of precipitation that fell on Greenland. By incorporating the isotopic data observed in the simulation, the model rendered an accurate prediction of how water moves over Greenland.

“It’s really important to be able to predict what’s going to happen to Greenland in the warming world as accurately as possible,” Rozmiarek said. “We demonstrated how useful water vapor isotope data is by successfully improving an existing model.”

Melting ice sheet

About 125,000 years ago, when Earth was warmer than preindustrial levels, Greenland was covered by a significantly smaller ice sheet, and the sea level was as much as 19 feet higher than today. As the planet continues to warm, the Greenland ice sheet could see dramatic changes and even shrink to its size back then, Rozmiarek said.

The Greenland ice sheet contains a massive amount of freshwater, and that water, if leaving the system, could lead to significant increases in global sea level. The United Nations estimated that rising sea levels caused by climate change currently impact 1 billion people worldwide.

Rozmiarek hopes to return to Greenland and other parts of the Arctic to conduct more flights and gather additional data.

“It’s like we just figured out how to discover fingerprints at a crime scene. This is a concrete step forward in understanding where water is going and where it is coming from in this important system at a time when we need it most,” he said.

Unlike conventional metals such as copper or gold that have well-understood electrical properties, strange metals behave in much more complex ways, making their inner workings beyond the realm of textbook description. Led by Qimiao Si, the Harry C. and Olga K. Wiess Professor of Physics and Astronomy, the research team turned to quantum Fisher information (QFI), a concept from quantum metrology used to measure how electron interactions evolve under extreme conditions, to find answers. Their research shows that electron entanglement, a fundamental quantum phenomenon, peaks at a quantum critical point: the transition between two states of matter.

“Our findings reveal that strange metals exhibit a unique entanglement pattern, which offers a new lens to understand their exotic behavior,” Si said. “By leveraging quantum information theory, we are uncovering deep quantum correlations that were previously inaccessible.”

A new way to study strange metals

In most metals, electrons move in an orderly fashion, following well-established laws of physics. Strange metals, however, break these rules, showing unusual resistance to electricity and behaving in unusual ways at very low temperatures. To explore this puzzle, the researchers focused on a theoretical model called the Kondo lattice, which describes how magnetic moments interact with surrounding electrons.

At a critical transition point, these interactions become so intense that the fundamental building blocks of electrical behavior, known as quasiparticles, vanish. Using QFI, the researchers tracked the origin of this quasiparticle loss to how electron spins become entangled, finding that entanglement reaches its peak precisely at this quantum critical point.

This novel approach applies QFI, primarily used in quantum information and precision measurements, to the study of metals.

“By integrating quantum information science with condensed matter physics, we are pivoting in a new direction in materials research,” Si said.

Possible path to more efficient energy

The researchers’ theoretical calculations unexpectedly matched real-world experimental data, specifically aligning with results from inelastic neutron scattering, a technique used to probe materials at the atomic level. This connection reinforces the idea that quantum entanglement plays a fundamental role in the behavior of strange metals.

Understanding strange metals is more than just an academic challenge; it could have significant technological benefits. These materials share a close connection with high-temperature superconductors, which have the potential to transmit electricity without energy loss. Unlocking their properties could revolutionize power grids, making energy transmission more efficient.

The study also demonstrates how quantum information tools can be applied to other exotic materials. Strange metals could play a role in future quantum technologies, where enhanced entanglement is a valuable resource. The research provides a new framework for characterizing these complex materials by showing when entanglement peaks.

The research team included Rice’s Yuan Fang, Yiming Wang, Mounica Mahankali and Lei Chen along with Haoyu Hu of the Donostia International Physics Center and Silke Paschen of the Vienna University of Technology. Their work was supported by the National Science Foundation, the Air Force Office of Scientific Research, the Robert A. Welch Foundation and the Vannevar Bush Faculty Fellowship program.