OREGON STATE UNIVERSITY

college of science

Globe-trotting pollutants raise some cancer risks four times higher than predicted

CORVALLIS, Ore. -- A new way of looking at how pollutants ride through the atmosphere has quadrupled the estimate of global lung cancer risk from a pollutant caused by combustion, to a level that is now double the allowable limit recommended by the World Health Organization.

The findings, published this week in the Proceedings of the National Academy of Sciences Early Edition online, showed that tiny floating particles can grow semi-solid around pollutants, allowing them to last longer and travel much farther than what previous global climate models predicted.

Scientists said the new estimates more closely match actual measurements of the pollutants from more than 300 urban and rural settings.

The study was done by scientists at Oregon State University, the Department of Energy’s Pacific Northwest National Laboratory, or PNNL, and Peking University. The research was primarily supported by PNNL.

"We developed and implemented new modeling approaches based on laboratory measurements to include shielding of toxics by organic aerosols, in a global climate model that resulted in large improvements of model predictions," said PNNL scientist and lead author Manish Shrivastava.

"This work brings together theory, lab experiments and field observations to show how viscous organic aerosols can largely elevate global human exposure to toxic particles, by shielding them from chemical degradation in the atmosphere."

Pollutants from fossil fuel burning, forest fires and biofuel consumption include air-polluting chemicals known as polycyclic aromatic hydrocarbons, or PAHs. In the United States, the Environmental Protection Agency has identified several PAHs as cancer-causing agents.

But PAHs have been difficult to represent in past climate models. Simulations of their degradation process fail to match the amount of PAH that is actually measured in the environment.

To look more closely at how far PAHs can travel while riding shielded on a viscous aerosol, the researchers compared the new model's numbers to PAH concentrations actually measured by Oregon State University scientists at the top of Mount Bachelor in the central Oregon Cascade Range.

“Our team found that the predictions with the new shielded models of PAHs came in at concentrations similar to what we measured on the mountain,” said Staci Simonich, a toxicologist and chemist in the College of Agricultural Sciences and College of Science at OSU, and international expert on the transport of PAHs.

“The level of PAHs we measured on Mount Bachelor was four times higher than previous models had predicted, and there’s evidence the aerosols came all the way from the other side of the Pacific Ocean.”

These tiny airborne particles form clouds, cause precipitation and reduce air quality, yet they are the most poorly understood aspect of the climate system.

A smidge of soot at their core, aerosols are tiny balls of gases, pollutants, and other molecules that coalesce around the core. Many of the molecules that coat the core are what's known as "organics." They arise from living matter such as vegetation -- leaves and branches, for example, or even the molecule responsible for the pine smell that wafts from forests.

Other molecules such as pollutant PAHs also stick to the aerosol. Researchers long thought that PAHs could move freely within the organic coating of an aerosol. This ease of movement allowed the PAH to travel to the surface where ozone -- a common chemical in the atmosphere -- can break it down.

But scientists' understanding of aerosols has changed in the last five years or so.

Recent experiments led by PNNL coauthor Alla Zelenyuk show that, depending on the conditions, the aerosol coatings can actually be quite viscous. If the atmosphere is cool and dry, the coating can become as viscous as tar, trapping PAHs and other chemicals. By preventing their movement, the viscous coating shields the PAHs from degradation.

Researchers developed a new way of representing PAHs in a global climate model, and ran it to simulate PAH concentrations from 2008 to 2010. They examined one of the most carcinogenic PAHs in particular, called BaP. Simulations were compared to data from 69 rural sites and 294 urban sites worldwide, and showed that predictions from shielded PAHs were far more accurate than previous, unshielded ones.

Scientists also analyzed how far the protected PAHs could travel, using both old and new models. In all cases, the shielded PAHs traveled across oceans and continents, whereas in the previous version they barely moved from their country of origin.

To look at the impact globe-trotting PAHs might have on human health, Shrivastava combined a global climate model, running either the shielded PAH scenario or the previous unshielded one, with a lifetime cancer risk assessment model developed by coauthors Huizhong Shen and Shu Tao, both then at Peking University.

Globally, the previous model predicted half a cancer death out of every 100,000 people, which is half the limit outlined by the World Health Organization (WHO) for PAH exposure. But using the new model, which showed that shielded PAHs actually travel great distances, the global risk was four times that, or two cancer deaths per 100,000 people, which exceeds WHO standards.

The WHO standards were not exceeded everywhere. It was higher in China and India and lower in the United States and Western Europe. The extent of shielding was also much lower over the tropics compared to the mid- and high-latitudes. As the aerosols traversed the warm and humid tropics, ozone could get access to the PAHs and oxidize them.

"We don't know what implications more PAH oxidation products over the tropics have for future human or environmental health risk assessments,” said Shrivastava. “We need to better understand how the shielding of PAHs varies with the complexity of aerosol composition, atmospheric chemical aging of aerosols, temperature and relative humidity. I was initially surprised to see so much oxidation over the tropics."

Other supporters of this research included the National Institute of Environmental Health Sciences, the National Science Foundation, the Ministry of Education, Youth and Sports of the Czech Republic, and the Department of Energy Office of Science.

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Staci Simonich, 541-737-9194

staci.simonich@oregonstate.edu

Mary Beckman, 509-375-3688

mary.beckman@pnnl.gov

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Airborne transport

Pollutant transport to regions


Aerosol formation
Aerosol formation and transport

New technique could lead to safer, more efficient uranium extraction, aid environmental cleanup

CORVALLIS, Ore. – The separation of uranium, a key part of the nuclear fuel cycle, could potentially be done more safely and efficiently through a new technique developed by chemistry researchers at Oregon State University.

The technique uses soap-like chemicals known as surfactants to extract uranium from an aqueous solution into a kerosene solution in the form of hollow clusters. Aside from fuel preparation, it may also find value in legacy waste treatment and for the cleanup of environmental contamination.

The research at OSU involves a unique form of uranium discovered in 2005, uranyl peroxide capsules, and how those negatively charged clusters form in alkaline conditions. Results were recently published in the European Journal of Inorganic Chemistry.

“This is a very different direction,” said study lead author Harrison Neal, a graduate student in Oregon State’s College of Science. “A lot of the work done now is in acid, and we’re at the other end of the pH scale in base. It’s a very different approach, overall using less harmful, less toxic chemicals.”

Throughout the nuclear fuel cycle, many separations are required – in mining, enrichment and fuel fabrication, and then after fuel use, for the recovery of usable spent isotopes and the encapsulation and storage of unusable radioactive components.

“When you use nuclear fuel, the radioactive decay products poison the fuel and make it less effective,” said May Nyman, professor of chemistry at Oregon State and corresponding author on the research. “You have to take it, dissolve it, get the good stuff out and make new fuel.”

Nyman notes the work represents significant fundamental research in the field of cluster chemistry because it allows for the study of uranyl clusters in the organic phase and can pave the way to improved understanding of ion association.

“With extracting these clusters into the organic phase, the clusters themselves are hollow, so when we get them into the organic solution, they’re still containing other atoms, molecules, other ions,” Neal added. “We can study how these ions interact with these cages that they’re in. The fundamental research is understanding how the ions get inside and what they do once they’re inside because they’re stuck there.”

When the clusters form, each contains 20 to 60 uranium atoms, “so we can extract them in whole bunches instead of one at a time,” Nyman said. “It’s an atom-efficient approach.”

Existing separation techniques require two extraction molecules for every uranium ion, whereas the OSU technique requires less than one extraction molecule per ion.

Scientists from the University of Notre Dame collaborated on the research, which was supported by the U.S. Department of Energy.

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uranyl peroxide capsules

Uranyl peroxide capsules

Ancient, scary and alien-looking specimen forms a rarity in the insect world – a new order

CORVALLIS, Ore. – Researchers at Oregon State University have discovered a 100-million-year-old insect preserved in amber with a triangular head, almost-alien and “E.T.-like” appearance and features so unusual that it has been placed in its own scientific “order” – an incredibly rare event.

There are about 1 million described species of insects, and millions more still to be discovered, but every species of insect on Earth has been placed in only 31 existing orders. Now there’s one more.

The findings have been published in the journal Cretaceous Research and describe this small, wingless female insect that probably lived in fissures in the bark of trees, looking for mites, worms or fungi to feed on while dinosaurs lumbered nearby. It was tiny, but scary looking.

“This insect has a number of features that just don’t match those of any other insect species that I know,” said George Poinar, Jr., an emeritus professor of entomology in the OSU College of Science and one of the world’s leading experts on plant and animal life forms found preserved in the semi-precious stone amber.

“I had never really seen anything like it. It appears to be unique in the insect world, and after considerable discussion we decided it had to take its place in a new order.”

Perhaps most unusual, Poinar said, was a triangular head with bulging eyes, with the vertex of the right triangle located at the base of the neck. This is different from any other known insect, and would have given this species the ability to see almost 180 degrees by turning its head sideways.

The insect, probably an omnivore, also had a long, narrow, flat body, and long slender legs. It could have moved quickly, and literally seen behind itself. It also had glands on the neck that secreted a deposit that scientists believe most likely was a chemical to repel predators.

The insect has been assigned to the newly created order Aethiocarenodea, and the species has been named Aethiocarenus burmanicus, in reference to the Hukawng Valley mines of Myanmar – previously known as Burma – where it was found. Only one other specimen of this insect has been located, also preserved in Burmese amber, Poinar said.

Those two specimens, which clearly belong to the same species, now comprise the totality of the order Aethiocarenodea. The largest order of insects, by comparison, is Coleoptera, the beetles, with hundreds of thousands of known species.

Needless to say, this species from such ancient amber is long extinct. It obviously had special features that allowed it to survive in the forests of what is now Burma, 100 million years ago, but for some unknown reason it disappeared. Loss of its preferred habitat is a likely possibility.

“The strangest thing about this insect is that the head looked so much like the way aliens are often portrayed,” Poinar said. “With its long neck, big eyes and strange oblong head, I thought it resembled E.T. I even made a Halloween mask that resembled the head of this insect. But when I wore the mask when trick-or-treaters came by, it scared the little kids so much I took it off.”

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George Poinar, Jr.

poinarg@science.oregonstate.edu

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New order

New order of insect


Strange head

Strange head


Neck glands
Neck glands

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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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 directions
Switching direction

Chemical trickery corrals ‘hyperactive’ metal-oxide cluster

CORVALLIS, Ore. – After decades of eluding researchers because of chemical instability, key metal-oxide clusters have been isolated in water, a significant advance for growing the clusters with the impeccable control over atoms that’s required to manufacture small features in electronic circuits.

Oregon State University chemists created the aqueous cluster formation process. It yielded a polyoxocation of zinc, aluminum and chromium that is not protected by the organic ligand shell that is usually required to capture such molecules from water.

“Our discovery is exciting in that it provides both new fundamental understanding and new materials, and useful applications are always built on a foundation of fundamental understanding,” said May Nyman, a professor of chemistry at Oregon State.

Metal oxides – compounds produced when metals combine with oxygen – serve a variety of important purposes. For example, titanium dioxide is a catalyst that degrades pollutants, and aluminum oxides and iron oxides are coagulants used as the first step in purifying drinking water.

“Metal oxides influence processes everywhere,” Nyman said. “They control the spread of contaminants in the environment. They are the touchscreen of your cellphone. The metal-oxide cluster forms are in your body storing iron and in plants controlling photosynthesis. Most of these processes are in water. Yet scientists still know so little about how these metal oxides operate in nature, or how we can make them with the absolute control needed for high-performance materials in energy applications.” 

Results of the research by the OSU College of Science’s Center for Sustainable Materials Chemistry were recently published in the journal Chem.

“We devised some synthetic processes so we can trick the clusters into forming,” Nyman said. “The main thing that we do is control the chemistry so the clusters grow not in the solution where they are highly reactive, but only at the surface, where the water evaporates and they instantly crystallize into a solid phase. Once in the solid phase, there’s no danger of reacting and precipitating metal oxide or hydroxide in an uncontrolled way.”

The clusters created in the research are spherical, contain about 100 atoms, and measure 1 nanometer across.

“Once we have synthesized these, we can prepare a solution of them, and they’re all exactly the same size and contain the same number of atoms,” Nyman said. “This gives us control over making very small features.

“The size of the feature is controlled by the size of the cluster. All metals on the periodic table act differently, and only a few have the right chemistry that behaves well enough to yield these clusters. For the rest of them, we need to innovate new chemistries to discover their cluster forms. The transition metals are particularly hard to control, yet they are earth-abundant and some of the most important metals in energy and environmental technologies.”

Metal-oxo clusters are usually isolated from water with ligands – molecules that protect the cluster surface and prevent precipitation of metal hydroxides.

In this study, an OSU team that included graduate students Lauren Fullmer, Sara Goberna-Ferron and Lev Zakharov overcame the need for ligands with a three-pronged strategy: pH-driven hydrolysis by oxidative dissolution of zinc; metal nitrate concentrations 10 times higher than conventional syntheses; and azeotropic evaporation for driving simultaneous cluster assembly and crystallization at the surface of the solution.

Meanwhile, the team’s computational collaborators in Catalonia provided a deeper understanding of the most stable arrangement of metal and oxygen atoms in the cluster.

“Contrary to common cluster growth, the fully assembled cluster is never detected in the reaction solution,” Nyman said. “Because the reactive clusters do not persist in solution, uncontrolled precipitation of metal hydroxide is avoided. In this sense, we have discovered a new way metal oxides can grow.”

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ZnCrAl-crystals2

Metal-oxide crystals

Marine incentives programs may replace 'doom and gloom' with hope

CORVALLIS, Ore. – Incentives that are designed to enable smarter use of the ocean while also protecting marine ecosystems can and do work, and offer significant hope to help address the multiple environmental threats facing the world’s oceans, researchers conclude in a new analysis.

Whether economic or social, incentive-based solutions may be one of the best options for progress in reducing impacts from overfishing, climate change, ocean acidification and pollution, researchers from Oregon State University and Princeton University say in a new report published this week in Proceedings of the National Academy of Sciences.

And positive incentives – the “carrot” – work better than negative incentives, or the “stick.”

Part of the reason for optimism, the researchers report, is changing awareness, attitudes and social norms around the world, in which resource users and consumers are becoming more informed about environmental issues and demanding action to address them. That sets the stage for economic incentives that can convert near-disaster situations into sustainable fisheries, cleaner water and long-term solutions.

“As we note in this report, the ocean is becoming higher, warmer, stormier, more acidic, lower in dissolved oxygen and overfished,” said Jane Lubchenco, the distinguished university professor in the College of Science and advisor in marine studies at Oregon State University, lead author of the new report, and U.S. science envoy for the ocean at the Department of State.

“The threats facing the ocean are enormous, and can seem overwhelming. But there’s actually reason for hope, and it’s based on what we’ve learned about the use of incentives to change the way people, nations and institutions behave. We believe it’s possible to make that transition from a vicious to a virtuous cycle. Getting incentives right can flip a disaster to a resounding success.”

Simon A. Levin, the James S. McDonnell distinguished university professor in ecology and evolutionary biology at Princeton University and co-author of the publication, had a similar perspective.

“It is really very exciting that what, until recently, was theoretical optimism is proving to really work,” Levin said. “This gives me great hope for the future.”

The stakes are huge, the scientists point out in their study.

The global market value of marine and coastal resources and industries is about $3 trillion a year; more than 3 billion people depend on fish for a major source of protein; and marine fisheries involve more than 200 million people. Ocean and coastal ecosystems provide food, oxygen, climate regulation, pest control, recreational and cultural value.

“Given the importance of marine resources, many of the 150 or more coastal nations, especially those in the developing world, are searching for new approaches to economic development, poverty alleviation and food security,” said Elizabeth Cerny-Chipman, a postdoctoral scholar working with Lubchenco.  “Our findings can provide guidance to them about how to develop sustainably.”

In recent years, the researchers said in their report, new incentive systems have been developed that tap into people’s desires for both economic sustainability and global environmental protection. In many cases, individuals, scientists, faith communities, businesses, nonprofit organizations and governments are all changing in ways that reward desirable and dissuade undesirable behaviors.

One of the leading examples of progress is the use of “rights-based fisheries.” Instead of a traditional “race to fish” concept based on limited seasons, this growing movement allows fishers to receive a guaranteed fraction of the catch, benefit from a well-managed, healthy fishery and become part of a peer group in which cheating is not tolerated.

There are now more than 200 rights-based fisheries covering more than 500 species among 40 countries, the report noted. One was implemented in the Gulf of Mexico red snapper commercial fishery, which was on the brink of collapse after decades of overfishing. A rights-based plan implemented in 2007 has tripled the spawning potential, doubled catch limits and increased fishery revenue by 70 percent.

“Multiple turn-around stories in fisheries attest to the potential to end overfishing, recover depleted species, achieve healthier ocean ecosystems, and bring economic benefit to fishermen and coastal communities,” said Lubchenco.  “It is possible to have your fish and eat them too.”

A success story used by some nations has been combining “territorial use rights in fisheries,” which assign exclusive fishing access in a particular place to certain individuals or communities, together with adjacent marine reserves. Fish recover inside the no-take reserve and “spillover” to the adjacent fished area outside the reserve. Another concept of incentives has been “debt for nature” swaps used in some nations, in which foreign debt is exchanged for protection of the ocean.

“In parallel to a change in economic incentives,” said Jessica Reimer, a graduate research assistant with Lubchenco, “there have been changes in behavioral incentives and social norms, such as altruism, ethical values, and other types of motivation that can be powerful drivers of change.”

The European Union, based on strong environmental support among its public, has issued warnings and trade sanctions against countries that engage in illegal, unregulated and unreported fishing. In the U.S., some of the nation’s largest retailers, in efforts to improve their image with consumers, have moved toward sale of only certified sustainable seafood.

Incentives are not a new idea, the researchers noted. But they emphasize that their power may have been under-appreciated.

“Recognizing the extent to which a change in incentives can be explicitly used to achieve outcomes related to biodiversity, ecosystem health and sustainability . . .  holds particular promise for conservation and management efforts in the ocean,” they wrote in their conclusion.

Funding was provided by OSU and the National Science Foundation.

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Jane Lubchenco, 541-737-5337

lubchenco@oregonstate.edu

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Catch share
Catch share program

Rockfish siblings shed new light on how offspring diffuse and disperse

CORVALLIS, Ore. – A splitnose rockfish’s thousands of tiny offspring can stick together in sibling groups from the time they are released into the open ocean until they move to shallower water, research from Oregon State University shows.

The study conducted in the OSU College of Science sheds new light on how rockfish, a group of multiple species that contribute to important commercial and recreational fisheries in the Northwest, disperse through the ocean and “recruit,” or take up residence in nearshore habitats. Previously it was believed rockfish larvae dispersed chaotically to wherever currents carried them.

“When you manage populations, it’s really important to understand where the young are going to and where the young are coming from – how populations are connected and replenished,” said Su Sponaugle, a professor of integrative biology based at OSU’s Hatfield Marine Science Center. “This research helps us better understand what’s possible about offspring movement. We don’t know fully by what mechanisms the larvae are staying together, but these data are suggestive that behavior is playing a role.”

The findings were published today in Proceedings of the National Academy of Sciences. Primary funding came from the Hatfield Marine Science Center’s Mamie L. Markham Research Award.

The discovery of “spatial cohesion” among the larvae came via the collection of newly settled rockfish in a shallow nearshore habitat off the central Oregon coast. Nearly 500 juvenile fish that had started out up to six months earlier as transparent larvae at depths of a few hundred meters were collected and genetically analyzed, with the results showing that 11.6 percent had at least one sibling in the group.

“That’s much higher than we would have expected if they were randomly dispersing,” Sponaugle said.

Bearing live young – a female can release thousands of able-to-swim larvae at a time – and dwelling close to the sea floor in the benthic zone, rockfishes make up a diverse genus with many species.

Adult splitnose rockfish live in deep water – usually 100 to 350 meters – but juveniles often settle in nearshore habitats less than 20 meters deep after spending up to a year in the open sea. Taking into account dynamic influences such as the California Current, siblings recruiting to the same area suggest they remained close together as larvae rather than diffusing randomly and then reconnecting as recruits.

“This totally changes the way we understand dispersal,” said lead author Daniel Ottmann, a graduate student in integrative biology at the Hatfield Marine Science Center. “We’d thought larvae were just released and then largely diffused by currents, but now we know behavior can substantially modify that.”

Splitnose rockfish range from Alaska to Baja California and can live for more than 100 years. Pelagic juveniles – juveniles in the open sea – often aggregate to drifting mats of kelp, and the large amount of time larvae and juveniles spend at open sea is thought to enable them to disperse great distances from their parental source.

“This research gives us a window into a stage of the fishes’ life we know so little about,” added Kirsten Grorud-Colvert, an assistant professor of integrative biology at OSU’s Corvallis campus. “We can’t track the larvae out there in the ocean; we can’t look at their behavior early and see where they go. But this genetic technique allows us to look at how they disperse, and it changes the conversation. Now that we know that siblings are ending up in the same places, we can consider how to more effectively manage and protect these species.”

Because larval aggregation shapes the dispersal process more than previously thought, Ottmann said, it highlights the need to better understand what happens in the pelagic ocean to affect the growth, survival and dispersal of the larvae.

“Successful recruitment is critical for the population dynamics of most marine species,” he said. “Our findings have far-reaching implications for our understanding of how populations are connected by dispersing larvae.”

In addition, Grorud-Colvert adds, there’s the simple and substantial “gee whiz” factor of the findings.

“These tiny little fish, a few days old, out there in the humongous ocean, instead of just going wherever are able to swim and stay close together on their epic journey,” she said. “These tiny, tiny things, sticking together in the open ocean – it’s cool.”

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Steve Lundeberg, 541-737-4039

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Splitnose rockfish

Bacteria discovery offers possible new means of controlling crop pest

CORVALLIS, Ore. – A bacterium common in insects has been discovered in a plant-parasitic roundworm, opening up the possibility of a new, environmentally friendly way of controlling the crop-damaging pest.

The worm, Pratylenchus penetrans, is one of the “lesion nematodes” -- microscopic animals that deploy their mouths like syringes to extract nutrients from the roots of plants, damaging them in the process. This particular nematode uses more than 150 species as hosts, including mint, raspberry, lily and potato.

The newly discovered bacterium is a strain in the genus Wolbachia, one of the world’s most widespread endosymbionts – organisms that live within other organisms. Wolbachia is present in roughly 60 percent of the globe’s arthropods, among them insects, spiders and crustaceans, and also lives in nematodes that cause illness in humans.

Postdoctoral scholar Amanda Brown in the Oregon State University Department of Integrative Biology was the lead author on the study, and recently accepted an assistant professor position at Texas Tech. Findings were published in the journal Scientific Reports.

Depending on the host species, Wolbachia can be an obligate mutualist – the bacteria and the host need each other for survival – or a reproductive parasite that manipulates the host’s reproductive outcomes in ways that harm the host and benefit the bacteria. Parasitic Wolbachia can cause its host populations to heavily skew toward female.

In the case of the crop-pest nematode, Pratylenchus penetrans, that Brown and her colleagues studied, the bacteria-host relationship appears to not be one of obligate mutualism – many examples of non-infected worms have been found, meaning the worm doesn’t rely on Wolbachia to survive.

But more study is needed to determine the exact nature of the relationship, said Dee Denver, an associate professor in the Department of Integrative Biology in the College of Science.

Whatever the relationship, simply discovering Wolbachia in Pratylenchus penetrans opens up the potential for managing the roundworm’s population via biocontrol rather than environment-damaging fumigants, such as methyl bromide, that are being phased out by the U.S. Environmental Protection Agency.

“We can use what’s already infecting them against them,” Denver said.

Nematode biocontrol would involve releasing Wolbachia-infected worms into farm fields whose worm populations weren’t infected. From there, a couple of situations, both favorable to the crops, might arise:

  •  The bacterium could hinder the worms’ ability to reproduce;
  •  It also might force the worm to devote energy to dealing with the bacterium, effectively distracting it from being as damaging to the crops as it otherwise would be.

Wolbachia is already being used as a biocontrol strategy in Colombia and Brazil, where infected mosquitoes are being released in an effort to control the Zika, dengue and malaria viruses. Mosquitoes are a vector for those diseases, but Wolbachia-infected mosquitoes pass the bacteria to their offspring, who lose their ability to transmit the diseases. Wolbachia also can interfere with the mosquitoes’ ability to reproduce at all.

“We can see where all of that goes and learn from it to help our decision making on how the strategy might get deployed to control the population of plant-parasitic nematodes,” Denver said. “One big thing with nematodes is the load. Many crops have some, but once you get above certain thresholds, fields go down and there are economic losses.”

In addition to the potential for an environmentally safe way to deal with a crop pest, the research is noteworthy for providing genomic evidence that nematodes, not arthropods, were the original Wolbachia hosts. The strain that OSU researchers discovered – known as wPpe – proved to be the earliest diverging Wolbachia, meaning the bacteria adapted to arthropods and then later evolved to reinvade nematodes.

“Were they originally reproductive parasites or play-nice mutualists?” Dee said. “These are outside the range of better-studied Wolbachia, so we don’t know, but we have preliminary data and we think they’re reproductive parasites.”

Another unanswered question: How widespread is Wolbachia among plant-parasitic nematodes?

“There are thousands of nematode species infecting plants,” Denver said. “Wolbachia has always been thought of as an arthropod thing, an insect thing. It was kind of a serendipitous discovery for us. We were sequencing genomes from nematodes for the purpose of understanding nematodes, and the mapping went to Wolbachia.”

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Steve Lundeberg, 541-737-4039

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Pratylenchus penetrans

Pratylenchus penetrans

Kelp forests globally resilient, but may need local solutions to environmental threats

CORVALLIS, Ore. – The first global assessment of marine kelp ecosystems shows that these critically-important habitats have exhibited a surprising resilience to environmental impacts over the past 50 years, but they have a wide variability in long-term responses that will call for regional management efforts to help protect their health in the future.

The findings were published today in Proceedings of the National Academy of Sciences.

Scientists noted that kelp forests have a remarkable ability to recover quickly from extreme damage, but they can still be overwhelmed in some instances by the combination of global and local pressures.

This points to the need for regional management efforts that carefully consider local conditions when trying to offset human-caused impacts from climate change, overfishing and direct harvests, researchers said.

Kelp forests, the largest species of algae in shallow, coastal waters almost everywhere except the tropics, are a globally important foundation species that occupy almost half of the world’s marine ecoregions. Often harvested directly, they help support commercial fisheries, nutrient cycling, shoreline protection, and are valued in the range of billions of dollars annually.

The new research was conducted by an international team of 37 scientists who analyzed changes in kelp abundance in 34 regions of the planet that had been monitored over the past 50 years.

“Kelp forests are cold-water, fast-growing species that can apparently withstand many types of environmental disturbances,” said Mark Novak, an assistant professor of integrative biology in the College of Science at Oregon State University, co-author of the study, and an organizer of the international group at the National Center for Ecological Analysis and Synthesis that conducted this research.

“The really surprising thing in this study was how much region-to-region variation we found, which is quite different from many other ecosystems. Thus, despite global threats like climate change and ocean acidification, the battle to protect our kelp forests of the future may best be fought locally – in the U.S., by states, counties, even individual cities and towns.”

These forests can grow fast, tall, and are highly resilient – but also are often on the coastal front line in exposure to pollution, sedimentation, invasive species, fishing, recreation and harvesting. Even though “they have some of the fastest growth rates of any primary producer on the planet,” the researchers wrote, there are limits to what they can take.

In their study the scientists concluded that of the kelp ecosystems that have been studied, 38 percent are in decline; 27 percent are increasing; and 35 percent show no detectable change. On a global scale, they are declining at 1.8 percent per year.

Where kelp resilience is eroding and leading to declines in abundance, impacts to ecosystem health and services can be far-reaching, the researchers wrote in their report.

This research was supported by the National Science Foundation, the University of California/Santa Barbara, and the state of California.

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Mark Novak, 541-737-3610

mark.novak@oregonstate.edu

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