OREGON STATE UNIVERSITY

scientific research and advances

‘Navigators’ help indigenous cancer patients overcome barriers to diagnosis, treatment

CORVALLIS, Ore. – New research shows that patient “navigators” are a valuable resource for American Indians and Alaskan Natives with cancer as they try to overcome barriers to diagnosis and care, and may offer a path to improved treatment outcomes.

The findings, recently published in the Journal of Primary Prevention, are important because American Indians and Alaskan Natives are stricken with cancer at the same rate as non-Hispanic white people but have lower five-year survivorship rates, and are more likely to die of cancer in general.

Indigenous patients in the Pacific Northwest working with a navigator were almost four times more likely to have a definitive diagnosis within a year of an abnormal screening result than patients without a navigator, the research indicated.

In addition, patients in the study praised their navigators’ ability to provide emotional and logistical support throughout the complicated and often-confusing treatment process. A navigator coordinated patients’ care between multiple providers and agencies and helped connect patients to support groups and other resources.

Megan Cahn, a postdoctoral research associate in Oregon State University’s College of Public Health and Human Sciences, was a co-author of the study along with scientists from the Northwest Tribal Epidemiology Center. The center, one of 12 in the nation, collaborates with the region’s tribes on health-related research, surveillance, training and technical assistance.

The patients in the study all received care through tribal community health clinics, which receive funding from the Indian Health Service. The project was part of a larger program by the National Cancer Institute examining the effectiveness of the patient navigator model in populations with sub-optimal cancer outcomes.

“One of the big concerns for tribal populations is that they have lower screening rates,” Cahn said. “If you don’t screen, then you don’t detect cancer until someone is showing symptoms. A big part of the program was to see if there was a way to get individuals with an abnormal screening result to get a definitive diagnosis, to shorten that window and get treatment in a timely fashion.

“We found that patients enrolled in a navigator program were 3.6 times more likely to have a definitive diagnosis within a year.”

The researchers also learned that not only was the navigator program measurably effective, the patients liked it – an important indicator of the program’s long-term success potential.

“If the patients don’t find it acceptable, the program won’t continue to work,” Cahn said.

A patient navigator was hired by the tribe at each of three tribal clinics in Idaho and Oregon, and researchers interviewed 40 patients for their perceptions of the program. The average age of the participants was 54.4, and 65 percent were female. Thirty-four of the 40 rated the navigator program as “good” or “excellent,” and one added she felt the navigator had saved her life.

In addition to the screening and diagnosis issue, the research found that the main barriers to cancer treatment cited by tribal members were physical and emotional obstacles - symptoms of the cancer itself or side effects from treatment, and “also the emotional response to the diagnosis.”

“There’s a lot of fear and anxiety and shock, and those fears often lead patients to be reluctant to continue with treatment,” Cahn said. “Some of them felt like they had received mistreatment or had been misdiagnosed, plus there were financial barriers: the cost of care and a lack of coordination regarding payment for the services.

“Other barriers were concerns around transportation – some people would have to travel several hours to get treatment, and the availability and cost of public transportation were problems. Navigators could help come up with strategies that were effective for addressing these logistical barriers.”

Sometimes a navigator would accompany a patient to an appointment and help the patient understand what the doctor was saying. Navigators also provided direct emotional support as well as referring patients to support groups.

“Patients said they valued that navigators were part of their communities and respected their culture,” Cahn said. “It made them feel like the navigators were invested in the community and the patients and their families.”

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Steve Lundeberg, 541-737-4039

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Scientists zero in on global ocean temperatures during last interglaciation period

CORVALLIS, Ore. – During the last major interglaciation period, when ice sheets in Greenland and Antarctica were smaller than today resulting in a global sea level that was 20 to 30 feet higher, scientists believe ocean temperatures were warmer than at most times in the Earth’s recent history.

However, those estimates of ocean temperatures show a high level of uncertainty, making it difficult to accurately project warming into the future and its impacts on sea level rise.

Now a team of scientists has assembled data from around the world in a comprehensive analysis of global ocean temperatures during the interglaciation period from 129,000 to 116,000 years ago. The team found that global average ocean temperatures were roughly half a degree (Celsius) warmer during that period than during pre-industrial times and nearly identical to the average temperature over the last 20 years.

Results of the study, which was supported by the National Science Foundation, appear this week in the journal Science.

“Half a degree may not sound like very much, but in terms of average global ocean temperature, it actually is quite substantial,” said lead author Jeremy Hoffman, who led the work as a doctoral student at Oregon State University, and is now a staff scientist with the Science Museum of Virginia. “The problem is that computer models have not been able to simulate this amount of warming for the last interglaciation. Because these are the same models used to project future temperatures, this suggests that they may be missing important processes that would result in even warmer temperatures than now considered.”

The last interglaciation period was one of the warmest periods on Earth in the last 800,000 years. A previous study by Oregon State researchers and published in Science documented the higher sea levels and scientists have hypothesized that warmer ocean temperatures may have been part of the process.

Peter Clark, an Oregon State climate scientist and co-author on the study, said one reason for warmer temperatures during the last interglaciation, and the decline of the Greenland ice sheet, was a shift in Earth’s orbit around the sun.

“Although carbon dioxide levels then were comparable to the pre-industrial era, solar insolation in the northern hemisphere during the summer was much higher,” said Clark, who has the title of distinguished professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “This more intense solar insolation contributed to the warmer temperatures.”

The researchers believe the melting of the Greenland ice sheet weakened the Atlantic Meridional Overturning Circulation, or AMOC, a system of currents that usually brings warmer water from the tropics to the south. As it weakened, sea surface temperatures rose in the southern hemisphere, also contributing to warmer global temperatures.

“It was a double whammy,” Clark said. “Solar insolation warmed the northern hemisphere, a weakened AMOC warmed the south.”

Earth’s orbit around the sun is different today, resulting in less solar insolation. The planet has warmed by about one degree (Celsius) since 1750, however, because of human influence.

Other authors on the study included Andrew Parnell of University College Dublin in Ireland, and Feng He from the University of Wisconsin.

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Peter Clark, 541-737-1247

clarkp@geo.oregonstate.edu

Molecule shows ability to thwart pathogens’ genetic resistance to antibiotic

CORVALLIS, Ore. – Oregon State University researchers have developed a new weapon in the battle against antibiotic-resistant germs - a molecule that neutralizes the bugs’ ability to destroy the antibiotic.

Scientists at OSU were part of an international collaboration that demonstrated the molecule’s ability to inhibit expression of an enzyme that makes bacteria resistant to a wide range of penicillins.

The molecule is a PPMO, short for peptide-conjugated phosphorodiamidate morpholino oligomer. The enzyme it combats is known as New Delhi metallo-beta-lactamase, or NDM-1, and it’s accompanied by additional genes that encode resistance to most if not all antibiotics.

“We’re targeting a resistance mechanism that’s shared by a whole bunch of pathogens,” said Bruce Geller, professor of microbiology in OSU’s College of Science and College of Agricultural Sciences, who’s been researching molecular medicine for more than a decade. “It’s the same gene in different types of bacteria, so you only have to have one PPMO that’s effective for all of them, which is different than other PPMOs that are genus specific.”

The Oregon State study showed that in vitro the new PPMO restored the ability of an antibiotic -- in this case meropenem, an ultra-broad-spectrum drug of the carbapenem class -- to fight three different genera of bacteria that express NDM-1. The research also demonstrated that a combination of the PPMO and meropenem was effective in treating mice infected with a pathogenic strain of E. coli that is NDM-1 positive.

Results of the study, supported by a grant from the National Institutes of Health, were recently published in the Journal of Antimicrobial Chemotherapy.

Geller says the PPMO will likely be ready for testing in humans in about three years.

“We’ve lost the ability to use many of our mainstream antibiotics,” Geller said. “Everything’s resistant to them now. That’s left us to try to develop new drugs to stay one step ahead of the bacteria, but the more we look the more we don’t find anything new. So that’s left us with making modifications to existing antibiotics, but as soon as you make a chemical change, the bugs mutate and now they’re resistant to the new, chemically modified antibiotic.”

That progression, Geller explains, made the carbapenems, the most advanced penicillin-type antibiotic, the last line of defense against bacterial infection.

“The significance of NDM-1 is that it is destroys carbapenems, so doctors have had to pull out an antibiotic, colistin, that hadn’t been used in decades because it’s toxic to the kidneys,” Geller said. “That is literally the last antibiotic that can be used on an NDM-1-expressing organism, and we now have bacteria that are completely resistant to all known antibiotics. But a PPMO can restore susceptibility to antibiotics that have already been approved, so we can get a PPMO approved and then go back and use these antibiotics that had become useless.”

In addition to Geller, the research team included Oregon State postdoctoral scholars Erin Sully and Lixin Li and OSU undergraduate student Christina Moody, as well as scientists from Sarepta Therapeutics, Harvard Medical School, the University of Fribourg, and the University of Texas Southwestern.

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Steve Lundeberg, 541-737-4039

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Millions of people with metabolic syndrome may need more vitamin E

CORVALLIS, Ore. – New research has shown that people with metabolic syndrome need significantly more vitamin E – which could be a serious public health concern, in light of the millions of people who have this condition that’s often related to obesity.

A study just published in the American Journal of Clinical Nutrition also made it clear that conventional tests to measure vitamin E levels in the blood may have limited accuracy compared to tests made in research laboratories, to the point that conventional tests can actually mask an underlying problem.

Vitamin E – one of the more difficult micronutrients to obtain by dietary means – is an antioxidant important for cell protection. It also affects gene expression, immune function, aids in repair of wounds and the damage of atherosclerosis, is important for vision and neurologic function, and largely prevents fat from going rancid.

Nutrition surveys have estimated that 92 percent of men and 96 percent of women in the United States fail to get an adequate daily intake of vitamin E in their diet. It is found at high levels in almonds, wheat germ, various seeds and oils, and at much lower levels in some vegetables and salad greens, such as spinach and kale.

This study was done by researchers in the Linus Pauling Institute at Oregon State University and the Human Nutrition Program at The Ohio State University, as a double-blind, crossover clinical trial focusing on vitamin E levels in people with metabolic syndrome. It was supported by the National Institutes of Health, the National Dairy Council and DSM Nutrition.

“The research showed that people with metabolic syndrome need about 30-50 percent more vitamin E than those who are generally healthy,” said Maret Traber, a professor in the OSU College of Public Health and Human Sciences, and Ava Helen Pauling Professor in the Linus Pauling Institute.

“In previous work we showed that people with metabolic syndrome had lower bioavailability of vitamin E. Our current work uses a novel approach to measure how much vitamin E the body needs. This study clearly demonstrates that people with metabolic syndrome need a higher intake of this vitamin.”

More than 30 percent of the American public are obese, and more than 25 percent of the adults in the United States meet the criteria for metabolic syndrome, putting them at significantly increased risk for cardiovascular disease and type-2 diabetes – primary causes of death in the developed world.

That syndrome is defined by diagnosis of three or more of several conditions, including abdominal obesity, elevated lipids, high blood pressure, pro-inflammatory state, a pro-thrombotic state and insulin resistance or impaired glucose tolerance.

This research, for the first time, also clearly outlined a flaw with conventional approaches to measuring vitamin E.

By “labeling” vitamin E with deuterium, a stable isotope of hydrogen, scientists were able to measure the amount of the micronutrient that was eliminated by the body, compared to the intake. The advanced research laboratory tests, which are not available to the general public, showed that people with metabolic syndrome retained 30-50 percent more vitamin E than healthy people – showing that they needed it. When the body doesn’t need vitamin E, the excess is excreted.

But in the group with metabolic syndrome, even as their tissues were taking up and retaining the needed vitamin E, their blood levels by conventional measurement appeared about the same as those of a normal, healthy person.

“We’ve discovered that vitamin E levels often look normal in the blood, because this micronutrient is attracted to high cholesterol and fat,” Traber said. “So vitamin E can stay at higher levels in the circulatory system and give the illusion of adequate levels, even as tissues are deficient.

“This basically means that conventional vitamin E blood tests as they are now being done are useless.”

The findings support the conclusion that people with metabolic syndrome have higher levels of oxidative and inflammatory stress, scientists said in their conclusion, and require more antioxidants such as vitamins E as a result.

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Maret Traber, 541-737-7977

maret.traber@oregonstate.edu

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Vitamin E
Vitamin E supplements

Air pollution and lack of physical activity pose competing threats to children in China

CORVALLIS, Ore. – Children and adolescents in mainland China are facing two serious and conflicting public health threats: ongoing exposure to air pollution and an increasingly sedentary lifestyle with little regular physical activity outside school.

Health workers and policymakers need to find ways to address both of these issues so that

children can be more physically active without suffering the health risks caused by exposure to air pollution, an Oregon State University researcher suggests in a new commentary published this month in The Journal of Pediatrics

“The question is how do we balance the virtues of physical activity with the hazards of air pollution?” said Brad Cardinal, a kinesiology professor in the College of Public Health and Human Sciences at Oregon State University and a national expert on the benefits of physical activity. “Ultimately, we have to find ways for people to stay active despite the air pollution.”

Many cities and countries around the world grapple with air pollution issues, but there is particular concern for children growing up in China in part because they tend to commute more on foot or bike and their playgrounds and sports fields are often found near busy streets or highways, Cardinal said. The impacts of air pollution contributed to 1.2 million deaths in 2010. 

At the same time, very few Chinese children today are participating in moderate or vigorous physical activity outside of school, and the number of overweight and obese children in China has more than doubled in the last 25 years.

Children are particularly susceptible to adverse health impacts from both short- and long-term exposure to air pollution, in part because they have higher rates of respiration and tend to take shallower breaths. Air pollution has been associated with increases in asthma, chronic cough and other respiratory problems in children that are likely to be exacerbated by heavy breathing from vigorous exercise, Cardinal said. 

So how do public health officials approach these competing challenges? Cardinal and his co-author, Qi Si of Zhejiang University in China and a former visiting scholar at OSU, suggest the two problems should be addressed together.

They recommend four urgent steps for health officials and policymakers who are grappling with these issues: 

  • Increase awareness among parents, children, health workers, educators, and policymakers on the causes and impacts of air pollution on children and adolescents, as well as the potential harm when coupled with outdoor physical activity
  • Add air quality systems at school sites, so pollution can be measured when and where children are engaging in physical activity
  • Adjust the intensity of outdoor physical activity during the school day on the basis of air pollution monitoring results
  • Educate children about exercising in polluted environments, including instruction to stop activity when they notice problems such as coughing, chest tightness or wheezing

Since schools are the base for much of the physical activity of today’s children, they are a critical piece in addressing both issues, Cardinal said. Monitoring the micro-climate at a school would provide better, more localized information for school officials making decisions about whether children should be outside exercising or at what level of intensity. 

“Doing some kind of physical activity, even if it is not as vigorous, is still better than having no physical activity for the children,” he said.

Clothing accessories or fitness equipment could also be designed to help protect children from pollution during outdoor play activities on days when air quality levels were low, he said.

“The goal is to get people thinking about these complex problems and real-world solutions,” Cardinal said. “The hope is that someone will innovate appropriate solutions for addressing both of these problems.” 

The National Health and Fitness Technology Research Key Laboratory of Zhejiang Province provided support for this project.

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Brad Cardinal, 541-737-2506, brad.cardinal@oregonstate.edu

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El Niño, Pacific Decadal Oscillation implicated in domoic acid shellfish toxicity

CORVALLIS, Ore. – Researchers today reported in Proceedings of the National Academy of Sciences a strong correlation between toxic levels of domoic acid in shellfish and the warm-water ocean conditions orchestrated by two powerful forces – El Niño events and the Pacific Decadal Oscillation.

Using a combination of time-series data spanning two decades, the scientists not only showed a clear link between domoic acid and these larger climatic phenomena, but also developed a new model to predict with some accuracy the timing of domoic acid risks in the Pacific Northwest.

The model is based on interpreting the status of the “Oceanic Niño Index” and the Pacific Decadal Oscillation – both of which are measures of climate, ocean water movement, currents and temperature. It’s designed to help coastal resource managers more effectively monitor this issue and protect public health.

The findings were made by researchers from Oregon State University, the University of Oregon, the National Oceanic and Atmospheric Association (NOAA), and the Oregon Department of Fish and Wildlife. The work was primarily supported by NOAA.

Researchers also pointed out that the findings are particularly timely, given the potential for greater domoic acid outbreak occurrences as oceans continue to warm due to climate change.

Domoic acid, a potent neurotoxin produced by specific types of phytoplankton and ingested by shellfish, can cause serious health effects in humans and some other animals. In recent years, dangerous levels of these toxins have led to the repeated closure of crab and shellfish harvesting in the Pacific Northwest and elsewhere. The problem threatens public health, marine wildlife and can cost millions for coastal economies. Until now, its connection to larger climatic forces has been suspected, but not confirmed.

“In the natural world there are always variations, and it’s been difficult to connect a specific event to larger forces that operate over periods of years and decades,” said Angelicque White, an associate professor and research team leader in the OSU College of Earth, Oceanic and Atmospheric Sciences.

“To do so, long observational time-series are crucial. With NOAA’s commitment to sponsored coastal ocean research and monitoring, along with state support for monitoring shellfish toxins, we’ve finally been able to tease out short term variability from natural climate forcing.”

Beyond problems with domoic acid levels, White said, this correlation also appears to mirror problems with green crabs, an invasive species of significant concern in the Pacific Northwest. These same warm climate phases lead to increased numbers of green crabs in Oregon waters, where they compete with native Dungeness crabs. The conditions also deliver communities of lipid-poor “copepods” – types of small crustaceans that float with currents – from the south, that are associated with reduced salmon runs.

The new study shows that oscillations to positive, or warm-favorable conditions in natural climate cycles can reduce the strength of the south-flowing California Current. This allows more movement northwards of both warmer waters and higher levels of toxic plankton, and also brings that toxic mix closer to shore where it can infiltrate shellfish.

“Part of the concern is that a large influx of the plankton that produce domoic acid can have long-term impacts,” said Morgaine McKibben, an OSU doctoral student and lead author on the study.

“For example, razor clams are filter-feeders that bioaccumulate this toxin in their muscles, so they take much longer to flush it out than other shellfish. The higher the toxin levels, the longer it takes for razor clams to be safe to eat again, perhaps up to a year after warm ocean conditions have subsided.”

Domoic acid is produced by the diatom genus Pseudo-nitzschia, and enters the marine food web when toxic blooms of these micro-algae are ingested by animals such as anchovies and shellfish. Referred to as “amnesic shellfish poisoning,” human symptoms can range from gastrointestinal disturbance to seizures, memory loss or, rarely, death. It was only first identified as a public health threat in 1987, and has been monitored on the U.S. West Coast since 1991.

Domoic acid events have been linked to mass deaths of marine mammals, like sea lions, sea otters, dolphins and whales. And closures of Pacific Northwest beaches to shellfish harvests, such as those that occurred in 2003, 2015 and 2016, can result in large economic impacts to coastal towns and tourism. In 2015, domoic-acid related closures led to a decline in value of nearly $100 million for the West Coast Dungeness crab fishery, according to the Fisheries of the U.S. Report 2015.

“Advance warning of when domoic acid levels are likely to exceed our public health thresholds in shellfish is extremely helpful,” said Matt Hunter, co-author of the study with the Oregon Department of Fish and Wildlife. “Agencies like mine can use this model to anticipate domoic acid risks and prepare for periods of more intensive monitoring and testing, helping to better inform our decisions and ensure the safety of harvested crab and shellfish.”

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Angelicque White, 541-737-6397

awhite@coas.oregonstate.edu

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Off-grid power in remote areas will require special business model to succeed

CORVALLIS, Ore. – Low-cost, off-grid solar energy could provide significant economic benefit to people living in some remote areas, but a new study suggests they generally lack the access to financial resources, commercial institutions and markets needed to bring solar electricity to their communities.

Around the world, more than 1.2 billion people lack access to basic electricity service. The majority of those people are living in developing nations, in rural or isolated areas with high rates of poverty. Steep costs and remote terrain often make it impractical or even impossible to extend the electric grid. 

Developing a successful business model that could deliver off-grid power to this market will require addressing challenges unique to the population, an Oregon State University researcher concluded in a study published recently in Renewable and Sustainable Energy Reviews.

“Surviving and growing in this market is very different than in a typical commercial enterprise,” said Inara Scott, an assistant professor in the College of Business. “There are a lot of people working on off-grid solar products on the small scale, but the problem becomes how can they scale the programs up and make them profitable?” 

When rural, isolated communities do gain access to solar power, the impact on residents can be profound, Scott said. Children are more likely to go to and complete schooling, because they have light to study by. Kerosene lamps, which create a lot of indoor air pollution, are no longer needed, improving people’s health. And work hours are increased, giving people more time to earn money or build home-based businesses.

“Providing electricity starts an incredible cycle of improvement for communities without reliance on charities or government aid,” she said. “There are also environmental benefits to encouraging sustainable development using renewable resources.” 

The market for small solar lighting and charging units has grown dramatically in the last few years, and solar home systems offer cleaner, safer and cheaper lighting over time than kerosene, the primary alternative for lighting in developing nations. But even a small cost can be out of reach for people whose annual incomes are often less than $3,000 per year, Scott said.

She examined successful business models for serving these populations, known as “base of the pyramid” markets, and successful renewable energy enterprises, looking for intersections that might aid businesses looking to market solar energy to base-of-pyramid markets. 

Scott found that a successful enterprise would include four primary components, and she developed a framework around them. Her recommendations:

  • Community interaction: Work with local communities to understand local norms, culture, social issues and economic systems that might influence the effort.
  • Partnerships: Join forces with other companies, government organizations, non-profit groups or non-governmental organizations to share ideas and resources and gain support.
  • Local capacity building: People in the community may lack product knowledge and have little experience with technology, while the community may not have typical distribution channels. Consider the potential customers as both producers and consumers, training local entrepreneurs as distributors, marketers and equipment installation/repair technicians.
  • Barriers unique to the off-grid market: Address issues such as financing of upfront costs, which may be prohibitive to consumers; educate people on the products and their benefits; build trust in quality and reliability; and develop multiple strong distribution networks.

“You’re not going to be successful just trying to sell a product,” she said. “This is really a social enterprise, with the goal of trying to bring people out of poverty while also emphasizing sustainable development.” 

There are a lot of socially-minded enterprises with good intentions that would like to work in these rural, remote and high-poverty areas, Scott noted. Her framework could serve as a checklist of sorts for organizations looking to put their ideas into action, she said.

“It’s a way to pause for a minute and ask yourself if you have all the right pieces in place to be successful,” she said.

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Inara Scott, 541-737-4102, Inara.Scott@oregonstate.edu

Scientists discover a molecular motor has a “gear” for directional switching

CORVALLIS, Ore. – A study published today offers a new understanding of the complex cellular machinery that animal and fungi cells use to ensure normal cell division, and scientists say it could one day lead to new treatment approaches for certain types of cancers.

The research revealed a totally unexpected behavior about a “motor” protein that functions as chromosomes are segregated during cell division. The findings were published in Nature Communications.

The work was led by Weihong Qiu, an assistant professor of physics in the College of Science at Oregon State University, in collaboration with researchers from Henan University in China and the Uniformed Services University of the Health Sciences in Maryland.

Motor proteins are tiny molecular machines that convert chemical energy into mechanical work. They are the miniature “vehicles” of a cell, and move on a network of tracks commonly referred to as the cytoskeleton. They shuttle cellular cargos between locations and generate forces to position chromosomes. But in spite of intensive research efforts over many years, mechanisms underlying the actions of many motor proteins are still unclear.

In this study, researchers focused on a particular motor protein, called KlpA, and used a high-sensitivity light microscopy method to directly follow the movement of individual KlpA molecules on the cytoskeleton track. They discovered that KlpA is able to move in opposite directions - an unusual finding. KlpA-like motor proteins are thought to be exclusively one-way vehicles.

The researchers also discovered that KlpA contains a gear-like component that enables it to switch direction of movement. This allows it to localize to different regions inside the cell so it can help ensure that chromosomes are properly divided for normal cell division.  

“In the past, KlpA-like motor proteins were thought to be largely redundant, and as a result they haven’t been studied very much,” Qiu said.

“It’s becoming clear that KlpA-like motors in humans are crucial to cancer cell proliferation and survival. Our results help better understand other KlpA-like motor proteins including the ones from humans, which could eventually lead to novel approaches to cancer treatment.”

Qiu and colleagues say they are excited about their future research, which may uncover the design principle at the atomic level that allows KlpA to move in opposite directions. And there may be other applications.

“KlpA is a fascinating motor protein because it is the first of its kind to demonstrate bidirectional movement,” Qiu said. “It provides a golden opportunity for us to learn from Mother Nature the rules that we can use to design motor protein-based transport devices.  Hopefully in the near future, we could engineer motor protein-based robotics for drug delivery in a more precise and controllable manner.”

The work was done with partial support from the National Science Foundation.

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Weihong Qiu, 541-737-7377

weihong.qiu@physics.oregonstate.edu

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Switching direction

Varmint hunters’ ammo selection influences lead exposure in avian scavengers

CORVALLIS, Ore. – Varmint hunters’ choice of ammunition plays a role in the amount of lead that scavengers such as golden eagles could ingest, a new study shows, and offers a way to minimize the lead exposure to wildlife.

Using a new bullet-fragment recovery technique known as “digestion,” the research also suggests that radiographs, or X-rays, a common tool for estimating how much of the toxic metal left is behind in shot pests or game animals, tend to produce low estimates.

A team of researchers that included Oregon State University undergraduate student Mason Wagner and U.S. Geological Survey scientists collected 127 Belding’s ground squirrel carcasses from alfalfa fields in southern Oregon and northern California.

Eleven western states produce roughly 40 percent of the U.S.’s alfalfa, and burrowing mammals such as ground squirrels and prairie dogs can cause significant yield loss. Shooting the rodents is an important form of pest control as well as a popular recreational pastime throughout the West.

The carcasses are typically left on the fields, where avian scavengers like eagles, hawks and kestrels descend upon the carrion to feed both themselves and their nestlings.

This study looked at how much lead remained in the carcasses and how that correlated with the type of bullet used. Models were also created to estimate from radiographs the amount of lead left in a carcass and the potential effect of the lead on nestlings’ mortality, growth and production of an enzyme critical to the blood’s ability to carry oxygen.

Results of the study by Oregon State’s College of Agricultural Sciences and the USGS were recently published in PLOS ONE.

The research found 80 percent of shot carcasses had detectible fragments of lead. The study also found bullet type didn’t have an effect on the number of fragments, but it did influence the mass of the retained fragments. Also, smaller carcasses showed more “pass-through,” i.e. less retained lead.

Squirrels shot with high-velocity, high-mass .17-caliber Super Mag bullets, for example, had 28 times the retained fragment mass of those shot with .22-caliber solid bullets. One percent of the Super Mags’ original mass was left behind, by far the highest percentage of any ammo type, and the Super Mag fragments also dispersed more than two times farther through the carcass – making them more likely to be eaten by a scavenging animal.

Modeling suggested that hawk and eagle nestlings fed regularly with shot ground squirrels could likely lose more than half the production of the key enzyme ALAD throughout the nestling period, though no nestlings would be expected to die of lead poisoning. They could, though, eat enough lead to impair late-nestling-stage growth, but by then they would have done most of their growing anyway.

The digestion procedure for extracting bullet fragments involved processing carcasses into a solution that was run through sieves and a gold-prospecting sluice box. Researchers used digestion on 30 carcasses to determine a relationship between digestion results and radiography results.

“We found that radiographs are not very accurate at estimating how much lead is left in a carcass,” said study co-author Collin Eagles-Smith, a USGS ecologist and OSU courtesy assistant professor of fisheries and wildlife. “They underestimate density when there are more small fragments. Small ones are the pieces that are more digestible and likely to enter the circulatory system.”

Radiography has also been used to estimate how much lead is present in shot game animals such as deer and elk.

In addition to providing a check on the accuracy of estimating via radiography, the research also suggests a way for hunters to minimize the amount of lead left in varmint carcasses.

“The sheer number of carcasses after a hunting session is a challenge to pick up, assuming you can even find all of the carcasses,” said lead author Garth Herring, also a USGS ecologist. “Picking up every last carcass is not realistic, but there are choices people can make regarding ammunition that may result in smaller amounts of lead in the carcasses left behind.”

Eagles-Smith noted that rodenticides, an alternative to shooting, have their own toxicological implications.

“These pests are really an economic threat to farmers, and shooting them is one method to control their numbers,” he said. “Choosing an ammunition type, such as .22-caliber solid bullets, that creates substantially fewer fragments can be a way to minimize lead exposure to scavengers and other wildlife.” 

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Steve Lundeberg, 541-737-4039

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Belding's Ground Squirrel

Belding's ground squirrel

New tag revolutionizes whale research - and makes them partners in science

NEWPORT, Ore. – A sophisticated new type of “tag” on whales that can record data every second for hours, days and weeks at a time provides a view of whale behavior, biology and travels never before possible, scientists from Oregon State University reported today in a new study.

This “Advanced Dive Behavior,” or ADB tag, has allowed researchers to expand their knowledge of whale ecology to areas deep beneath the sea, over thousands of miles of travel, and outline their interaction with the prey they depend upon for food.

It has even turned whales into scientific colleagues to help understand ocean conditions and climate change.

The findings, just published in the journal Ecology and Evolution, showed sperm whales diving all the way to the sea floor, more than 1000 meters deep, and being submerged for up to 75 minutes. It reported baleen whales lunging after their food; provided a basis to better understand whale reactions to undersea noises such as sonar or seismic exploration; and is helping scientists observe how whales react to changes in water temperature.

The ADB tag is a pretty revolutionary breakthrough,” said Bruce Mate, professor and director of OSU’s Marine Mammal Institute in the College of Agricultural Sciences. “This provides us a broad picture of whale behavior and ecology that we’ve never had before.

“This technology has even made whales our partners in acquiring data to better understand ocean conditions and climate change,” Mate said. “It gives us vast amounts of new data about water temperatures through space and time, over large distances and in remote locations. We’re learning more about whales, and the whales are helping us to learn more about our own planet.”

The new tag, the researchers say, expands by several orders of magnitude the observations that can be made of whale feeding and behavior. Researchers say it’s showing what whales do while underwater; when, how and where they feed; how they might be affected by passing ships or other noises; and what types of water temperatures they prefer.

In the new study, researchers outlined the continued evolution and improvements made in the ADB technology from 2007-15, in which it was used on sperm, blue and fin whales. The research has been supported by the Office of Naval Research, the U.S. Navy and the International Association of Oil and Gas Producers.

“By using this technology on three different species, we’ve seen the full range of behavior that is specific to each species,” said Daniel Palacios, a co-author on the study. “Sperm whales, for instance, really like to dive deep, staying down a long time and appearing to forage along the seafloor at times. During summer the baleen whales will feed as much as possible in one area, and then they move on, probably after the prey density gets too low.”

Unlike earlier technology that could not return data from the deep sea for much longer than a day, the new ADB tags are designed to acquire data constantly, for up to seven weeks at a time, before they detach from the whale, float to the surface and are retrieved in the open sea to download data. The retrieval itself is a little tricky – scientists compare it to searching for a hamburger floating in thousands of square miles of open ocean – but it has worked pretty well, thanks to the tags transmitting GPS-quality locations and flashing LED lights once they have released.

The tag can sense water depth, whale movement and body orientation, water temperature and light levels.

“With this system we can acquire much more data at a lower cost, with far less commitment of time by ships and personnel,” said Ladd Irvine, the corresponding author on the study. “This tag type yields amazing results. It’s going to significantly expand what we can accomplish, learning both about whale ecology and the ocean itself.”

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Source: 

Bruce Mate, 541-867-0202

bruce.mate@oregonstate.edu

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Whale tag

Whale with tag


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Whale with tag

Whale travels
Whale travel and feeding