Io is the most volcanically active moon in our solar system. It hosts more than 400 active volcanoes, spewing out sulfur gases that give Io its yellow-white-orange-red colors when they freeze out on its surface.

Although it is extremely thin — about a billion times thinner than Earth’s atmosphere — Io has an atmosphere that can teach us about Io’s volcanic activity and provide us a window into the exotic moon’s interior and what is happening below its colorful crust.

Previous research has shown that Io’s atmosphere is dominated by sulfur dioxide gas, ultimately sourced from volcanic activity. “However, it is not known which process drives the dynamics in Io’s atmosphere,” said Imke de Pater of the University of California, Berkeley. “Is it volcanic activity, or gas that has sublimated (transitioned from solid to gaseous state) from the icy surface when Io is in sunlight?”

To distinguish between the different processes that give rise to Io’s atmosphere, a team of astronomers used ALMA to make snapshots of the moon when it passed in and out of Jupiter’s shadow (they call this an “eclipse”).

“When Io passes into Jupiter’s shadow, and is out of direct sunlight, it is too cold for sulfur dioxide gas, and it condenses onto Io’s surface. During that time we can only see volcanically-sourced sulfur dioxide. We can therefore see exactly how much of the atmosphere is impacted by volcanic activity,” explained Statia Luszcz-Cook from Columbia University, New York.

Thanks to ALMA’s exquisite resolution and sensitivity, the astronomers could, for the first time, clearly see the plumes of sulfur dioxide (SO₂) and sulfur monoxide (SO) rise up from the volcanoes. Based on the snapshots, they calculated that active volcanoes directly produce 30-50 percent of Io’s atmosphere.

The ALMA images also showed a third gas coming out of volcanoes: potassium chloride (KCl). “We see KCl in volcanic regions where we do not see SO₂ or SO,” said Luszcz-Cook. “This is strong evidence that the magma reservoirs are different under different volcanoes.”

Io is volcanically active due to a process called tidal heating. Io orbits Jupiter in an orbit that is not quite circular and, like our Moon always faces the same side of Earth, so does the same side of Io always face Jupiter. The gravitational pull of Jupiter’s other moons Europa and Ganymede causes tremendous amounts of internal friction and heat, giving rise to volcanoes such as Loki Patera, which spans more than 200 kilometers (124 miles) across. “By studying Io’s atmosphere and volcanic activity we learn more about not only the volcanoes themselves, but also the tidal heating process and Io’s interior,” added Luszcz-Cook.

A big unknown remains the temperature in Io’s lower atmosphere. In future research, the astronomers hope to measure this with ALMA. “To measure the temperature of Io’s atmosphere, we need to obtain a higher resolution in our observations, which requires that we observe the moon for a longer period of time. We can only do this when Io is in sunlight since it does not spend much time in eclipse,” said de Pater. “During such an observation, Io will rotate by tens of degrees. We will need to apply software that helps us make un-smeared images. We have done this previously with radio images of Jupiter made with ALMA and the Very Large Array (VLA).”

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Imke de Pater and Statia Luszcz-Cook worked with Patricio Rojo of the Universidad de Chile, Erin Redwing of the University of California, Berkeley, Katherine de Kleer of the California Institute of Technology (Caltech), and Arielle Moullet of SOFIA/USRA in California.

This research titled “ALMA Observations of Io Going into and Coming out of Eclipse” has been accepted for publication in The Planetary Science Journal.

“There’s a gradual transition at the same latitude in North and South America,” said Erin Calfee, graduate student in the Department of Evolution and Ecology at the University of California, Davis, and first author on the paper, published Oct. 19 in PLOS Genetics. “There’s a natural barrier that is likely maintained by many different genetic loci.”

That barrier is mostly likely climate. Bees with majority African ancestry are unable to survive colder winters.

European colonists brought European species of honeybees (Apis mellifera) with them to the Americas as early as the 1600s. In addition to apiaries, these bees established in the wild alongside native bees.

In 1957, imported African honeybees of the subspecies Apis mellifera scutellata swarmed out of experimental hives in Brazil and started to rapidly spread, interbreeding with the resident European bees. Native to southern and eastern Africa, scutellata bees are known for their defensive behavior. They also carry some useful traits for beekeepers, such as resistance to Varroa mites.

Calfee, working with Professor Graham Coop and Associate Professor Santiago Ramirez from the Department of Evolution and Ecology and collaborators in Argentina, sequenced the genomes of bees collected at the northern and southern edges of the scutellata expansion.

They found that the bees at the northern and southern edges of the range have a highly variable mix of scutellata and European bee ancestry. The higher the latitude, the less scutellata ancestry is in the mix.

“The whole genome is tracking latitude and climate,” Calfee said. There are likely many genes involved in climate sensitivity and winter survival, she said. But Calfee also finds that in some parts of the genome scutellata ancestry has spread far beyond these climate limits in both North and South America, evidence that some scutellata genes are advantageous and not tied to climate sensitivity. In contrast, the researchers did not find any evidence for selection for European ancestry in the spread of scutellata bees.

The findings challenge the idea of a binary difference between “Africanized” and “European” honeybees, Ramirez said. In fact, all of these introduced honeybees are hybrids to some degree.

Diversity a resource for breeding bees

The results of the study could be of interest for breeding bees for desirable traits, such as resistance to pathogens. Although the researchers looked only at gene sequences and not the resulting phenotypes (except for one, wing length), the results do show which genetic loci are important because they are under selection in the hybrid zones.

Scutellata bees and hybrids have a lot more genetic diversity than European bees, and the researchers found that they lost very little of this diversity in their expansion from Brazil to California.

“Beekeepers can potentially draw from this genetic variation to breed for desirable traits,” Ramirez said. What started out as an invasion may become part of the solution to declining bee health.

“It makes sense but it’s kind of surprising because we have 1.5 million (honeybee) colonies being brought into California every spring to pollinate crops,” Ramirez said. Those domesticated bees are then trucked around the country, but they do not appear to have a large effect on the spread of African ancestry into feral honeybee populations.

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Materials provided by University of California – Davis. Original written by Andy Fell. Note: Content may be edited for style and length.

Medulloblastoma (MB), the most common pediatric brain tumor, is currently diagnosed based on clinical symptoms, examination of magnetic resonance imaging (MRI) scans and tumor biopsies. It is then monitored through routine MRIs to measure physical changes in the tumor. Clinicians also perform repeated lumbar punctures, commonly known as spinal taps, to collect cerebrospinal fluid (CSF) that is tested for the presence of tumor cells.

“If there are no tumor cells in the CSF, clinicians likely believe their treatment is effective and continue the course. However, there is often inconsistency between the CSF test results and the patient’s final outcome,” said Jia Li, PhD, research assistant professor in the Center for Epigenetics & Disease Prevention (CEDP) at the Texas A&M Institute of Biosciences and Technology, and the first author of the study, published in Science Advances. “Therefore, it is highly desirable to have a more sensitive way to systematically estimate and monitor the tumor response after treatment and, at the same time, confidently detect tumor recurrence before there is evident anatomical changes in the tumor seen through MRI or CT scans.”

In other words, clinicians want to be able to monitor the state of the tumor in patients so they can intervene at the earliest possible time if there is evidence that the tumor has recurred or is starting to grow aggressively again. Liquid biopsy — the method of detecting cancer DNA or other disease biomarkers in body fluids like blood — is increasingly being used to monitor adult cancers such as colorectal cancer and breast cancer. This technique is a relatively non-invasive way to assess cancer progression, response to therapy and recurrence. The current technology detects gene mutations associated with cancer within plasma. However, this approach is more challenging for pediatric brain cancers because these cancers often have very few mutations. According to the researchers, they can be described as being “genetically bland,” meaning they don’t harbor huge numbers of mutations to the DNA itself.

Instead, pediatric brain tumors frequently have epigenetic changes. In other words, instead of the DNA itself being changed by mutation, in the cancer cells, certain critical genes are turned on or turned off by epigenetic changes that regulate their activity. The presence of epigenetic abnormalities in pediatric brain cancers led the research team to reason that epigenetic markers in biological fluids such as CSF could be an effective way to detect and monitor these types of cancers.

The other problem with using liquid biopsy for pediatric brain cancer is that brain tumor DNA is scarcely detectable in plasma because of the blood-brain barrier, which prevents brain tumor DNA from being released into the blood stream. In contrast, CSF interacts with brain tumor cells in the central nervous system and can be used for liquid biopsy. However, CSF contains extremely low amounts of DNA, making it difficult to study.

Li, along with Yun Nancy Huang, PhD, MS, and Deqiang Sun, PhD, developed a new method to get around this issue and successfully profiled DNA methylation genome-wide from very low amounts of DNA in CSF. They used CSF samples obtained from a biobank built by physicians at Texas Children’s Hospital over the course of 20 years. “Tumor cells in the CSF degrade during circulation, but DNA lasts much longer than cells, and so cell-free tumor DNA (ctDNA) can be found in the biobank samples,” said Huang, who is an associate professor in the CEDP and a co-corresponding author of this study.

The researchers developed an experimental and computational method for analyzing this DNA. Their results revealed that the epigenetic marker, DNA methylation, can be detected in ctDNA from CSF, serving as a potential biomarker to report the status of the MB tumor and allow for prognosis.

“This is essentially a completely novel way of detecting DNA methylation in circulating DNA and using it for biomarker detection and quantitation in childhood cancer,” said Peter Davies, MD, PhD, professor at the Texas A&M University College of Medicine and director of the Center for Translational Cancer Research at the Institute of Biosciences and Technology, and co-author of the study.

Eventually, this research will lead to development of a biomarker kit that clinicians will be able to use for monitoring pediatric brain tumor patients. Many steps lay ahead toward that end, but these findings have generated much interest from physicians and show promise for clinical application.

“The biobank built by physicians at Texas Children’s Hospital is an invaluable resource,” Davies said. “All the samples were donated by patients with informed consent, and ultimately, it’s the willingness of patients and their families to allow their samples to be stored for future research that makes this kind of work possible.”

“This is a classic example of using ‘team science’ to answer really important questions that couldn’t be done without bringing together unique expertise,” said CEDP Director Roderick Dashwood, PhD, FRSB, professor at the College of Medicine, and co-author of the study. “We have unique expertise in the Texas Medical Center, but you need to bring these outstanding people together. That includes physicians, bioinformaticians and epigenetic experts. Those individuals are often located at different institutions, but we’re bringing them all together to address very important questions for clinical translation.”