The University of Alaska Fairbanks-led study tested 297 subsistence-caught fish, which included eight species — chum salmon, fourhorn sculpin, least cisco, humpback whitefish, starry flounder, Pacific herring, Pacific tomcod and sheefish. The average mercury levels for each species were at levels considered safe by the Alaska Department of Health and Social Services.

Local residents have wondered about mercury levels in Kotzebue Sound in recent years, due in part to discharges from the Red Dog Mine, which is located about 80 miles inland. Its presence has contributed to questions about the safety of Kotzebue-area subsistence foods.

The study was initiated by the Native Village of Kotzebue, which contacted Todd O’Hara, a UAF professor of veterinary toxicology and pharmacology. Researchers worked with local subsistence fishermen, who donated a variety of Kotzebue Sound fish species from their catches in 2105, 2016 and 2018 for testing.

Of the hundreds of samples tested, only four individual fish exceeded the “unrestricted consumption” levels set by state officials. The average mercury levels in each species were well below that threshold.

UAF researcher Andrew Cyr, who wrote about the study for the journal Environmental Research this month, said the results are consistent with other data that show fish throughout Alaska are safe for consumption with respect to mercury levels.

The study also compared mercury levels to those recorded in Kotzebue Sound fish 15 years ago. It found no increase in concentrations of the contaminant during that time, an indication that mercury hasn’t increased in the food web.

“There’s a lot of information and misinformation about fish and mercury, but the vast majority of fish in Alaska are safe for consumption,” said Cyr, who began the study as a doctoral student and now works for UAF’s Biomedical Learning and Student Training program. “The nutritional benefits of consuming Alaska fish far outweigh the risk of mercury.”

Cyr and other researchers have discussed their findings at several events in Kotzebue during the past year, including outreach at Kotzebue schools, a fish clinic and a local radio show.

Alex Whiting, the environmental program director for the Native Village of Kotzebue, said subsistence users in the area have been interested in mercury levels in local fish for more than 20 years. He called the new data “another valuable contribution to our ongoing interest in mercury and marine biota.”

“It is as much an effort to document baselines for future comparative studies as it is for understanding current levels and any areas for consumptive concerns,” said Whiting, who also contributed to the study.

Other contributors to the study included UAF researchers Andres Lopez and Matthew Wooller, and Alaska State Veterinarian Robert Gerlach.

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New research led by Newcastle University has shown that it is the volume of water used during the wash cycle, rather than the spinning action of the washing machine, which is the key factor in the release of plastic microfibres from clothes.

Millions of plastic microfibres are shed every time we wash clothes that contain materials such as nylon, polyester and acrylic.

Because these fibres are so small, they drain out of our washing machines and can ultimately enter the marine environment.

Once in the ocean, they are ingested by the animals living there and two years ago Newcastle University scientists showed for the first time these fibres have now reached the deepest parts of our ocean.

Working with Procter & Gamble in Newcastle, the team measured the release of plastic microfibres from polyester clothing for a range of cycles and water volumes.

Counting the fibres released, the team found the higher the volume of water the more fibres released, regardless of the speed and abrasive forces of the washing machine.

In fact, they found that on average, 800,000 more fibres were released in a delicate wash than a standard cycle.

Publishing their findings today in the academic journal Environmental Science and Technology, PhD student Max Kelly, who led the research, explained:

“Counterintuitively, we discovered that ‘delicate’ cycles release more plastic microfibres into the water, and then the environment, than standard cycles.

“Previous research has suggested the speed the drum spins at, the number of times it changes spinning direction during a cycle and the length of pauses in the cycle — all known as the machine agitation — is the most important factor in the amount of microfibre released.

“But we have shown here that even at reduced levels of agitation, microfibre release is still greatest with higher water-volume-to-fabric ratios.

“This is because the high volume of water used in a delicate cycle which is supposed to protect sensitive clothing from damage actually ‘plucks’ away more fibres from the material.”

Plastic pollution in our oceans

Plastic pollution is one of the biggest challenges facing society today and understanding the key sources is an important process to help reduce our impact on the environment.

Laundry has been recognised as a major contributor of microplastics but until now, precisely measuring the release of these fibres has been difficult due to the fact that it’s almost impossible to accurately simulate the reality of what happens in people’s machines in a lab setting.

Using a tergotometer — a benchtop device comprising of eight (1000 mL) washing vessels that simulate full-scale domestic washing, the team were able to carry out tests under different conditions, making changes to water volume, spin speed, temperature and time.

A DigiEye camera — digital colour imaging system — was then used to accurately calculate the amount of microfibres released.

To test whether the observations made using the tergotometers were reflective of full-size domestic washing machines, the team then tested the fabrics on a delicate wash cycle using identical washing machines in the test centre at Procter and Gamble (P&G).

The team showed that previous recommendations by groups to move towards high water volumes and low levels of agitation as a way of reducing the amount of microfibre released was actually making the problem worse.

Neil Lant, Research Fellow at P&G and co-author on the study, said:

“The appliance industry has started to introduce microfibre filters in some new washing machines and the textile industry is looking to reduce the fibre shedding levels of new clothing.

“We hope that the issue will ultimately be solved by such actions, and our work on the mechanistic causes will help in the development of these solutions.”

Max Kelly adds:

“Reducing the amount of plastic pollution is everyone’s responsibility and often it’s the small changes that make a huge difference.

“By avoiding high water-volume-to-fabric washes such as the delicate cycles and ensuring full wash loads then we can all do our bit to help reduce the amount of these synthetic fibres being released into the environment.

“Hopefully, these findings may also be used by manufacturers to influence the design of future washing machines and reduce our plastic footprint. Over time these changes could also see a global reduction in the amount of energy and water required to wash our clothes.”

The test, developed by GRAIL, Inc., uses next-generation sequencing technology to probe DNA for tiny chemical tags (methylation) that influence whether genes are active or inactive. When applied to nearly 3,600 blood samples — some from patients with cancer, some from people who had not been diagnosed with cancer at the time of the blood draw — the test successfully picked up a cancer signal from the cancer patient samples, and correctly identified the tissue from where the cancer began (the tissue of origin). The test’s specificity — its ability to return a positive result only when cancer is actually present — was high, as was its ability to pinpoint the organ or tissue of origin, researchers found.

The new test looks for DNA, which cancer cells shed into the bloodstream when they die. In contrast to “liquid biopsies,” which detect genetic mutations or other cancer-related alterations in DNA, the technology focuses on modifications to DNA known as methyl groups. Methyl groups are chemical units that can be attached to DNA, in a process called methylation, to control which genes are “on” and which are “off.” Abnormal patterns of methylation turn out to be, in many cases, more indicative of cancer — and cancer type — than mutations are. The new test zeroes in on portions of the genome where abnormal methylation patterns are found in cancer cells.

“Our previous work indicated that methylation-based assays outperform traditional DNA-sequencing approaches to detecting multiple forms of cancer in blood samples,” said the study’s lead author, Geoffrey Oxnard, MD, of Dana-Farber. “The results of the new study demonstrate that such assays are a feasible way of screening people for cancer.”

In the study, investigators analyzed cell-free DNA (DNA that had once been confined to cells but had entered the bloodstream upon the cells’ death) in 3,583 blood samples, including 1,530 from patients diagnosed with cancer and 2,053 from people without cancer. The patient samples comprised more than 20 types of cancer, including hormone receptor-negative breast, colorectal, esophageal, gallbladder, gastric, head and neck, lung, lymphoid leukemia, multiple myeloma, ovarian, and pancreatic cancer.

The overall specificity was 99.4%, meaning only 0.6% of the results incorrectly indicated that cancer was present. The sensitivity of the assay for detecting a pre-specified high mortality cancers (the percent of blood samples from these patients that tested positive for cancer) was 76%. Within this group, the sensitivity was 32% for patients with stage I cancer; 76% for those with stage II; 85% for stage III; and 93% for stage IV. Sensitivity across all cancer types was 55%, with similar increases in detection by stage. For the 97% of samples that returned a tissue of origin result, the test correctly identified the organ or tissue of origin in 89% of cases.

Detecting even a modest percent of common cancers early could translate into many patients who may be able to receive more effective treatment if the test were in wide use, Oxnard remarked.

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Their findings could have far-ranging implications for obesity in affluent countries and malnutrition in impoverished countries.

In the study, published this week by Science, Dr. Lora Hooper and her research team found that the commensal, or good, bacteria that live in the guts of mammals program the metabolic rhythms that govern the body’s absorption of dietary fat. Dr. Hooper, Chair of Immunology and a Howard Hughes Medical Institute Investigator, is senior author of the study.

The study also found that microbes program these so-called circadian rhythms by activating a protein named histone deacetylase 3 (HDAC3), which is made by cells that line the gut. Those cells act as intermediaries between bacteria that aid in digestion of food and proteins that enable absorption of nutrients.

The study, done in mice, revealed that HDAC3 turns on genes involved in the absorption of fat. They found that HDAC3 interacts with the biological clock machinery within the gut to refine the rhythmic ebb and flow of proteins that enhance absorption of fat. This regulation occurs in the daytime in humans, who eat during the day, and at night in mice, which eat at night.

“The microbiome actually communicates with our metabolic machinery to make fat absorption more efficient. But when fat is overabundant, this communication can result in obesity. Whether the same thing is going on in other mammals, including humans, is the subject of future studies,” added lead author Dr. Zheng Kuang, a postdoctoral fellow in the Hooper laboratory.

To go back in time, the story really starts with a few mice and crosstalk between two laboratories at UT Southwestern.

Dr. Hooper, who runs the University’s colony of germ-free mice, which are raised in environments that have no microbes, is also a Professor of Immunology and Microbiology and a member of the Center for the Genetics of Host Defense. She holds the Jonathan W. Uhr, M.D. Distinguished Chair in Immunology, and is a Nancy Cain and Jeffrey A. Marcus Scholar in Medical Research, in Honor of Bill S. Vowell.

Histone modifications — which are made by enzymes like HDAC3 — control the expression of genes that in turn make proteins that carry out the work of the cell. Not long ago, the Hooper laboratory decided to do a mouse study of histone modifications that seemed to rise and fall along with circadian rhythms.

In comparing normal, bacteria-laden mice with germ-free ones, researchers discovered some histone modifications — including those made by HDAC3 — were circadian in normal mice, but held steady at a flat level in germ-free mice.

That’s when Dr. Hooper contacted Dr. Eric Olson, Chair of Molecular Biology and Director of the Hamon Center for Regenerative Science and Medicine, who had done studies on HDAC3 in a different tissue, the heart. The two laboratories collaborated to develop a mouse that lacked HDAC3 only in the gut lining.

The mice they generated seemed unremarkable while eating a normal chow diet. However, when the researchers fed the mice a high fat, high sugar diet similar to one commonly consumed in the United States — they found something very different.

“We call it the junk food diet. I describe it as like driving through a fast food restaurant for a burger and fries and then stopping off at the donut shop,” she said. “Most mice on that diet become obese. To our surprise, those that had no HDAC3 in their intestinal lining were able to eat a high fat, high sugar diet and stay lean.”

Next, they compared the HDAC3-deficient mice to the germ-free mice. The researchers found that both groups of mice showed the same flat, nonrhythmic histone modifications, confirming HDAC3’s importance in circadian rhythms.

Every cell in the body has a molecular clock that governs bodily processes. The mouse study revealed that HDAC3 attaches to that cellular clock machinery to ensure absorption of fat is highest when mammals are awake and eating.

“Our results suggest that the microbiome and the circadian clock have evolved to work together to regulate metabolism,” she said.

Why would a system evolve to make us fat? Dr. Hooper believes it could have evolved to enable mammals to use energy efficiently in order to boost immunity in an environment with food scarcity.

“This regulatory interaction probably didn’t evolve to make us obese, but when combined with today’s calorie-rich diets, obesity arises,” she said, adding that this is speculation and the team is still working to understand all the components of the pathway.

“Our results also suggest that disrupting the interactions between the microbiota and the body’s clock could make us more likely to become obese. These disruptions happen frequently in modern life when we take antibiotics, work overnight shifts, or travel internationally. But we think that our findings might eventually lead to new treatments for obesity — and possibly malnutrition — by altering the bacteria in our guts.”

“Astronomers have struck a bonanza in searching for and detecting exoplanets of every size and stripe since the first confirmed exoplanet, a hot Jupiter, was discovered in 1995,” Boss explained. “Literally thousands upon thousands have been found to date, with masses ranging from less than that of Earth, to many times the mass of Jupiter.”

But there are still gaping holes in scientists’ knowledge about exoplanets that orbit their stars at distances similar to those at which our Solar System’s gas giants orbit the Sun. In terms of mass and orbital period, planets like Jupiter represent a particularly small population of the known exoplanets, but it’s not yet clear if this is due to biases in the observational techniques used to find them — which favor planets with short-period-orbits over those with long-period-orbits — or if this represents an actual deficit in exoplanet demographics.

All the recent exoplanet discoveries have led to a renewed focus on theoretical planet formation models. Two primary mechanisms exist for predicting how gas giant planets form from the rotating disk of gas and dust that surrounds a young star — bottom-up, called core accretion, and top-down, called disk instability.

The former refers to slowly building a planet through the collisions of increasingly larger material — solid dust grains, pebbles, boulders, and eventually planetesimals. The latter refers to a rapidly triggered process that occurs when the disk is massive and cool enough to form spiral arms and then dense clumps of self-gravitating gas and dust contract and coalesce into a baby planet.

While core accretion is considered the consensus planet-formation mechanism, Boss has long been a proponent of the competing disk instability mechanism, dating back to a seminal 1997 Science paper.

The just-published discovery by an Institute for Space Studies of Catalonia-led team of a star that’s a tenth the mass of our Sun and hosts at least one gas giant planet is challenging the core-accretion method.

The mass of a disk should be proportional to the mass of the young star around which it rotates. The fact that at least one gas giant — possibly two — was found around a star that’s so much smaller than our Sun indicates that either the original disk was enormous, or that core accretion does not work in this system. Orbital periods for lower mass stars are longer, which prevents core accretion from forming gas giants before the disk gas disappears, as core accretion is a much slower process than disk instability, according to Boss.

“It’s a great vindication for the disk instability method and a demonstration how one unusual discovery can swing the pendulum on our understanding of how planets form,” said one of the IEEC research team’s members, Guillem Anglada-Escudé, himself a former Carnegie postdoc.

Boss’ latest simulations follow the three-dimensional evolution of hot disks that start out in a stable configuration. On a variety of time scales, these disks cool down and form spiral arms, eventually resulting in dense clumps representing newborn protoplanets. Their masses and distances from the host star are similar to that of Jupiter and Saturn.

“My new models show that disk instability can form dense clumps at distances similar to those of the Solar System’s giant planets,” said Boss. “The exoplanet census is still very much underway, and this work suggests that there are many more gas giants out there waiting to be counted.”

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