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About Egghead

Egghead is a blog about research by, with or related to UC Davis. Comments on posts are welcome, as are tips and suggestions for posts. General feedback may be sent to Andy Fell. This blog is created and maintained by UC Davis University Communications, and mostly edited by Andy Fell.

Wild bees pollinate crops, but that’s not why they should be conserved

By Kathy Keatley Garvey

Wild bee diversity is declining worldwide at unprecedented rates, and steps must be taken to conserve them — and not just those that are the main pollinators of agricultural crops, declare 58 bee researchers in a study published June 16 in the journal Nature Communications.

“This study provides important support for the role of wild bees to crop pollination,” said co-author and pollination ecologist Neal Williams, associate professor in the UC Davis

Wild pollinators such as bumblebees contribute to crop production. (Credit: Kathy Keatley Garvey/UC Davis).

Wild pollinators such as bumblebees contribute to crop production. (Credit: Kathy Keatley Garvey/UC Davis).

Department of Entomology and Nematology. “At the same time, we found that in any one region, much of the pollination services from wild bees to a given crop come from just a few species, thus we need to be careful about using a simplistic economic ecosystem-services argument for biodiversity conservation and maintain actions that target biodiversity as specific goal.”

Wild, or non-managed bees, include bumble bees (genus Bombus), sweat bees (genus Lasioglossum) and small carpenter bees (genus Cerantina).

The study, led by David Kleijn of Wageningen University, The Netherlands, found that wild bees contribute about $3,251 per hectare ($1300 per acre) in “crop pollination services,” about the same as the economic contribution from “managed” bee colonies. However, they also found that 80 percent of the crop pollination from wild bees was provided by just two percent of wild bee species.

That means that the economic benefit of crop pollination might not be a good argument for conserving wild bee species, according to the authors. Measures taken to protect top pollinators might not benefit wild bee species as a whole.

The paper, “Delivery of Crop Pollination Services is an Insufficient Argument for Wild Pollinator Conservation,” is online at Among the co-authors are Robbin Thorp, distinguished emeritus professor of entomology at UC Davis, and conservation biologist Claire Kremen of UC Berkeley.


UC Davis Bee Biology (Harry H. Laidlaw Jr. Honeybee Research Facility)

UC Davis Häagen-Dazs Honeybee Haven 

Engineering student builds machines for battlebots

Travis Smith has always been interested in building things. This summer, the UC Davis graduate student will be on national television building robots and then watching his creations stand up to spikes, chainsaws and flamethrowers as a team member in the sixth series of “Battlebots” on the ABC network.

Travis Smith, a Ph.D. student in engineering, is taking part in the sixth season of the TV show "Battlebots."

Travis Smith, a Ph.D. student in engineering, is taking part in the sixth season of the TV show “Battlebots.”

In the show, teams build armed robots that fight it out in an arena full of hazards. Think FIRST Robotics, but with chainsaws.

Smith was a chemical engineering major at UC Berkeley during Battlebots’ original TV run from 2000 to 2002. After graduating, he worked for Lockheed Martin, earning a Master’s degree from the University of New Orleans along the way. He is currently working towards a Ph.D. in mechanical and aerospace engineering with Professor Jae Wan Park, studying design of fuel cells.

“Battlebots is why I switched from chemical to mechanical engineering,” Smith said. He has also volunteered as a mentor for high school students taking part in the FIRST Robotics Competition in the New Orleans region.

As part of the “Machine Corps” team for Battlebots, Smith specializes in machining and analysis.

“There are some interesting engineering problems, it’s very cool,” he said.

Filming began May 17 and the first of six episodes will air June 21 at 9 p.m. on ABC.

UC Davis graduate student to attend Lindau Nobel Laureate meeting

By Derrick Bang

Christopher Chapman, a Ph.D. student in the UC Davis Department of Biomedical Engineering, has been selected to attend the 65th annual Lindau Nobel Laureate Meeting, taking place June 28-July 3 in Lindau, Germany. Chapman will join a U.S. delegation of roughly 55 “young researchers,” as they’re designated by the Lindau committee.

Christopher Chapman, a PhD student in the UC Davis Department of Biomedical Engineering

The U.S. delegation will be among the Lindau Meeting’s approximately 650 global student and postdoctoral researchers from all three natural science Nobel Prize disciplines: medicine and physiology, physics, and chemistry. They’ll meet and confer with the 65 Nobel Laureates who will gather to interact with this next generation of leading scientists and researchers.

“I’m happily surprised,” Chapman admits. “The selection process began back in September 2014, and has taken awhile, so I’ve tried not to think about it too much. But now that I’ve been chosen, and the reality has sunk in, I’ve started talking to people, and now I’m getting quite excited.

“I’m already planning how to use this meeting for networking, because being able to build one’s network on an international scale doesn’t happen frequently. And, of course, I’m excited by the chance to interact and learn directly from Nobel Laureates. Since my work focuses on a wide range of areas within these three natural science disciplines, this is an incredible opportunity.”

Chapman is a member of the Multifunctional Nanoporous Metals Research Group headed by Erkin Şeker, a professor in the UC Davis Department of Electrical and Computer Engineering. Chapman earned twin undergraduate degrees in biomedical engineering and mechanical engineering in 2012, at North Carolina State University; he expects to complete his doctorate at UC Davis in 2016.

His research has focused on nanoporous gold. He is engineering a microchip-based testing platform to rapidly screen for materials and surface chemistries with the long-term goal of developing a next-generation neural electrode coating for making recordings from single brain cells.

Two other UC Davis scientists, Aimee Bryan and Pablo Zamora, attended the Lindau Nobel meeting in 2013.

The first Lindau Nobel Laureate Meeting took place in 1951. Today, the annual meetings provide a globally recognized forum for the transfer of knowledge between generations of scientists, while inspiring and motivating both Nobel Laureates and international “best talents.”

“Crosstalk” gives clues to diabetes

Sometimes, listening in on a conversation can tell you a lot. For Mark Huising, an assistant professor in the Department of Neurobiology, Physiology and Behavior at the UC Davis College of Biological Sciences, that crosstalk is between the cells that control your body’s response to sugar, and understanding the conversation can help us understand, and perhaps ultimately treat, diabetes.

Huising’s lab has now identified a key part of the conversation going on between cells in the pancreas. A hormone called urocortin 3, they found, is released at the same time as insulin and acts to damp down insulin production. A paper describing the work appears online on June 15 in the journal Nature Medicine.

“It’s a beautiful system,” Huising said. “It turns out that there is a lot of crosstalk going on in the islets to balance insulin and glucagon secretion. The negative feedback that urocortin 3 provides is necessary to tightly control blood sugar levels at all times.”

Diabetes affects millions of Americans every year. Both forms of the disease — type 1, “juvenile” or “insulin-dependent” diabetes, and type 2 or “adult-onset” diabetes — occur when the body fails to regulate the level of sugar properly.

Diabetes is tied to structures called the Islets of Langerhans in the pancreas. Within the islets, beta cells make insulin. Increasing blood sugar stimulates insulin production, which causes the body’s cells to pull sugar out of circulation.

The islets also house alpha cells, which make another hormone, glucagon, which acts on the liver to release more glucose into the bloodstream.

An islet of Langerhans with urocortin stained green in beta cells. Glucagon-making cells are stained red. Credit: Mark Huising.

An islet of Langerhans with urocortin stained green in beta cells. Glucagon-making cells are stained red. Credit: Mark Huising.

Urocortin 3 was originally identified as a hormone that is related to the signal in our brain that kick-starts our stress response. Instead, urocortin 3 is produced by islet beta cells and stored and released alongside insulin. In a series of experiments, Huising’s group showed that urocortin 3 causes another cell type in the islets, delta cells, to release somatostatin, which turns down insulin production and acts as a natural brake on the release of insulin.

Urocortin 3 is reduced in laboratory animal models of diabetes and in beta cells from diabetic patients. Without urocortin 3, islets produce more insulin, but at the same time lose control over how much insulin they release.

By understanding how different cells and systems communicate to regulate blood sugar, Huising hopes to get a better understanding of what happens when this regulation goes wrong, leading to the different forms diabetes. Eventually this approach could lead to new ways to treat or prevent the disease.

Coauthors on the study were, at UC Davis: Talitha van der Meulen, Anna Hunter and Christopher CowingZitron; Cynthia Donaldson, Elena Cáceres, Michael Adams and Andreas Zembrzycki at the Salk Institute, La Jolla; and Lynley Pound and Kevin Grove at Oregon Health Sciences University. The work was funded by the Juvenile Diabetes Research Foundation, the Clayton Medical Research Foundation Inc., and the National Institutes of Health.


Link to the full paper

Hartwell Foundation awards grant for work on juvenile diabetes


Brown pelicans released following Refugio oil spill

By Kat Kerlin

Rehabilitated pelicans once covered in oil from last month’s Refugio oil spill in Santa Barbara County were released today (June 12) at Goleta Beach.

Video: Rehabilitated pelicans returned into wild (LA Times)

Wildlife responders from the UC Davis Oiled Wildlife Care Network and California Department of Fish and Wildlife’s Office of Spill Prevention and Response (OSPR) placed satellite tracking devices on 12 brown pelicans affected by the spill.

Study to track rehabilitated birds’ survival

The devices will help researchers learn more about the survival rates of birds affected by oil spills and to see if they return to normal behaviors. Eight additional pelicans will be outfitted with the devices to serve as controls.

Twelve brown pelicans rehabilitated following the Refugio oil spill are being fitted with tracking backpacks before going back to the wild. Credit: Justin Cox/UC Davis

Twelve brown pelicans rehabilitated following the Refugio oil spill are being fitted with tracking backpacks before going back to the wild. Credit: Justin Cox/UC Davis

The solar-powered tracking devices each weigh 65 grams, about the weight of a “C” size battery, and are worn by the birds like a small backpack—with one loop in front of the wing, another behind the wing and two loops connected by Teflon ribbon under the bird’s body. The device allows pelicans to dive for fish with minimal disruption.

Track records

Researchers tracked oiled birds following the American Trader oil spill off Huntington Beach in 1990, but this study will use more advanced technology and newer rehabilitation methods. OWCN and OSPR are working with collaborators who have successfully tagged and tracked close to 100 brown pelicans after the Deepwater Horizon spill.

The oiled pelicans released today were recovered and cleaned after the spill in May and have been rehabilitating at the Los Angeles Oiled Bird Care and Education Center in the weeks since.

Other collaborators in the project include the U.S. Geological Survey, Clemson University, Humboldt State University’s Wildlife Department, U.S. Fish and Wildlife Service, and International Bird Rescue.

The study is being funded by the UC Davis Oiled Wildlife Care Network, which is based at the Karen C. Drayer Wildlife Health Center and the UC Davis School of Veterinary Medicine, and by OSPR.

More information

For updates on animals and birds rescued from the oil spill, follow the OWCN blog.

UC Davis Today: Wildlife experience the high price of oil (with video)

“Chromosome shattering” seen in plants, cancer

Plants can undergo the same extreme “chromosome shattering” seen in some human cancers and developmental syndromes, UC Davis researchers have found. Chromosome shattering, or “chromothripsis,” has until now only been seen in animal cells. A paper on the work is published in the online journal eLife.

The process could be applied in plant breeding as a way to create haploid plants with genetic material from only one parent, said Ek Han Tan, a postdoctoral researcher in the UC Davis Department of Plant Biology and first author on the paper. Although plants don’t get cancer, it might also allow cancer researchers to use the laboratory plant Arabidopsis as a model to study chromosome behavior in cancer.

Chromothripsis involves slicing chromosomes into apparently random pieces, and reassembling it like a broken vase, often with pieces completely missing or in the wrong place. Generally speaking, this is not a good thing, although in one recently published case a woman was cured of a genetic disorder when the gene responsible was lost due to chromothripsis.

Han Tan, Professor Luca Comai and colleagues were studying centromeres, the handles by which chromosomes are moved and allocated to daughter cells during cell division. They discovered that when a variant of the model plant Arabidopsis with weakened centromeres is crossed to a plant with normal centromeres, the resulting embryos undergo chromothripsis, the cut-and-reassembly process leading to “shattered chromosomes.”

Other authors on the study were: At UC Davis, Isabelle Henry, Keith Bradnam, Mohan Marimuthu and Ian Korf; Martin Lysak and Terezie Mandakova, Masaryk University, Czech Republic; and Maruthachalam Ravi, formerly at UC Davis and now at the Indian Institute of Science Education and Research, Thiruvananthapuram, India. The work began under the guidance of the late Simon Chan at UC Davis and was supported by the Howard Hughes Medical Institute and the Gordon and Betty Moore Foundation.

Death in the tide pools: Rapid die-off of urchins and sea stars a grim warning of climate change

By Kat Kerlin

In August 2011, scientists at the UC Davis Bodega Marine Laboratory walked into their labs to a strange, disturbing sight: Thousands of purple sea urchins and other marine invertebrates were dead in their tanks, which are fed directly by seawater. Outside, the tea-colored ocean washed up carcasses of red abalone, large sea stars, and football-sized, snail-like chitons.

Less conspicuous—but even more heavily impacted as a population—were the millions of purple sea urchins and tiny sea stars that died along a 62-mile stretch of coast in Northern California, according to a UC Davis-led study published in the journal PLOS ONE that documents the die-off.

“We might not have known urchins and six-armed sea stars were affected if lab-held animals hadn’t died right in front of us,” said the study’s lead author Laura Jurgens, a graduate student at UC Davis Bodega Marine Laboratory who earned her doctorate in May.

Long-term consequences

The scientists documented almost 100 percent mortality of purple sea urchins and six-armed sea stars over the study area, which stretched from southern Mendocino County to Bodega Bay in Sonoma County. Intertidal zones that once looked like pools of purple held only burrows in the bedrock—telltale markers that purple sea urchins were once there. Only 10 purple urchins were found in an area once home to millions of them.

Tidepools before (left) and after (right) the 2011 die off. Only burrows in the rock remained. Laura Jurgens/UC Davis Bodega Marine Laboratory

Tidepools before (left) and after (right) the 2011 die off. Only burrows in the rock remained. Laura Jurgens/UC Davis Bodega Marine Laboratory

The disappearance of these species to the area suggests long-term population and ecosystem consequences, the study said.

“We’re expecting real ecological changes in how these tide pools operate,” Jurgens said.

The silver-dollar-sized, six-armed sea star is a key tide-pool predator, and purple sea urchins serve as cleanup crews and recyclers for kelp detritus that washes ashore, processing the kelp into nutrients. Purple sea urchins also provide food for shorebirds and some mammals living along the coast.

 Algal bloom likely culprit

Unlike sea star wasting syndrome, a disease that has progressed over years as sea stars literally waste away, this die-off was fast, wiping out these two species in as little as a few days. The die-off also occurred about two years before recent incidences of sea star wasting syndrome were observed along the West Coast.

Six-armed sea stars like this one experienced almost 100 percent mortality across a 62-mile stretch of coast in Northern California in 2011. Credit: Laura Jurgens/UC Davis Bodega Marine Laboratory

Six-armed sea stars like this one experienced almost 100 percent mortality across a 62-mile stretch of coast in Northern California in 2011. Credit: Laura Jurgens/UC Davis Bodega Marine Laboratory

Instead, the study said the mass mortality was likely caused by a harmful algal bloom. Such blooms are expected to occur more often due to the combination of global warming, ocean acidification, and land-use changes.

Jurgens said that is all the more reason why documenting such mass mortality events is important to better understand — and prepare for –trends happening to ocean ecosystems.

‘We might forget’

Purple sea urchins have begun to recolonize the area. But it might be decades before the more home-bodied six-armed sea stars return to the area, since their babies can only crawl small distances away from their mothers. Males and females would need to arrive on floating debris to begin to repopulate the species here, which Jurgens said is unlikely to happen very often.

“If someone were to come to this area, they wouldn’t know these six-armed sea stars existed here, even though this has been a main part of their species range,” Jurgens said. “If something disappears and we don’t document it, we might not ever know it was there, and we might forget.”

Study support

The study was primarily funded by the National Science Foundation. It also received financial support from the Monitoring Enterprise, California Ocean Sciences Trust, Partnership for Interdisciplinary Studies of Coastal Oceans, the David and Lucile Packard Foundation and the California Department of Fish and Wildlife.

Co-authors from UC Davis Bodega Marine Laboratory and the UC Davis Coastal Marine Sciences Institute include evolution and ecology professors Brian Gaylord and Rick Grosberg, as well as Laura Rogers-Bennett from BML, UC Davis Wildlife Health Center, and the California Department of Fish and Wildlife. Other co-authors include UC Santa Cruz professor Peter Raimondi, and graduate student Lauren Schiebelhut and associate professor Michael Dawson from UC Merced.

More information:

Read the study:

Understanding how cells follow electric fields

Many living things can respond to electric fields, either moving or using them to detect prey or enemies. Weak electric fields may be important growth and development, and in wound healing: it’s known that one of the signals that guides cells into a wound to repair it is a disturbance in the normal electric field between tissues. This ability to move in response to an electric field is called galvanotaxis or electrotaxis.

UC Davis dermatology professor Min Zhao, Peter Devroetes at Johns Hopkins University and colleagues hope to unravel how these responses work, studying both body cells and Dictyostelium discoideum, an amoeba that lives in soil. Dictyostelium is unusual because it spends part of its life crawling around as a single-cell amoeba, but occasionally multiple amoebae will come together to form a fruiting body.

In a paper just published in the journal Science Signaling, Zhao and colleagues screened Dictyostelium for genes that affect electrotaxis. They used special barcoded microplates developed by Tingrui Pan, professor of biomedical engineering at UC Davis to screen hundreds of amoeba strains.

The team identified a number of genes, including one called PiaA, which encodes a critical component of a pathway controlling motility. Other genes associated with electrotaxis in Dictyostelium were also linked to the same pathway.

Video: Amoeba crawling in an electric field

Right now, no one nows how cells detect these very weak electric fields, Zhao said. The screening technique could be used to identify more genes linked to electrotaxis and help researchers piece together exactly how electrical signals are detected and turned into action.

Audio: Min Zhao and Peter Devroetes talk about the work in this Science podcast

Coauthors on the paper include biologists, engineers and mathematicians. They are: at UC Davis, Runchi Gao, Siwei Zhao, Yaohui Sun, Sanjun Zhao, Jing Gao, and Alex Mogilner; Jane Borleis, Stacey Willard, Ming Tang, Huaqing Cai, and Yoichiro Kamimura at Johns Hopkins University; Yuesheng Huang, Jianxin Jiang, Xupin Jiangat the State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing, China; and Zunxi Huang, Yunnan Normal University, Kunming, China.

The work was supported by the National Science Foundation (U.S.), the California Institute for Regenerative Medicine, National Institutes of Health, the National Science Foundation of China and the Wellcome Trust.

Previously: Cells and cell fragments move oppositely in electric fields


Help fund koala microbiome study

The koala might be the world’s cutest animal. It also has a strange and toxic diet, and koalas are threatened by chlamydia, a sexually transmitted disease. How are these things related?

Koalas live on eucalyptus leaves, which are so full of tannins that they are toxic to most animals. Koalas deal with this by having a special brew of bacteria in their gut that can digest the tannins in eucalyptus leaves. Baby koalas (joeys) acquire these microbes from their mothers by eating a special form of nutrient-rich feces, called “pap,” for the first two months after they wean from breast milk.

Could antibiotic treatment, given to cure koalas of chlamydia, affect their gut microbes? UC Davis graduate student Katie Dahlhausen plans to find out, working with Jonathan Eisen at the UC Davis Genome Center and Adam Polkinghorne at the University of the Sunshine Coast, Australia.

Dahlhausen is currently fundraising for the project through Indiegogo. Check out her project page and video.

Bugs and slugs ideal houseguests for seagrass health

By Kat Kerlin

Marine “bugs and slugs” make ideal houseguests for valuable seagrass ecosystems. They gobble up algae that could smother the seagrass, keeping the habitat clean and healthy. That’s according to results from an unprecedented experiment spanning the Northern Hemisphere and led by an international team of scientists, including marine biologists from UC Davis.

The study, led by the Virginia Institute of Marine Science, was conducted simultaneously at 15 sites across seven countries through a project called the Zostera Experimental Network, or ZEN, after the seagrass species Zostera marina.

“Our results show that small marine invertebrates are really important,” said Pamela Reynolds, a postdoctoral scholar at UC Davis and VIMS and the ZEN project coordinator.

Invertebrates like this isopod keep seagrass clean and healthy. (Pamela Reynolds)

Invertebrates like this isopod keep seagrass clean and healthy. (Pamela Reynolds)

“They graze down seaweeds that might otherwise smother the seagrass. It’s a really neat partnership — the animals get a home, and the seagrass stays clean. We found that the more diverse communities of these little algae-eating animals do a better job of keeping the seagrass clean and healthy.”

Reynolds said the results support that comprehensive coastal management should consider how to maintain robust populations of animals in addition to managing for the more conspicuous effects of pollution and disturbance.

Seagrasses declining

Seagrass meadows provide valuable fish nurseries and feeding grounds for birds, sea turtles and manatees. They sequester carbon, and their root systems help bind and protect coastlines. Yet, they are declining worldwide due to host of factors.

The researchers explored which of two known threats to seagrass has the greater impact on seagrass ecosystems: pollution from fertilizers or the loss of invertebrate species due, in part, to fishing.

The importance of biodiversity

To simulate nutrient pollution, the team members fertilized the seagrass similarly to how one would a lawn. Then they drove away small crustacean grazers by applying a chemical deterrent, simulating changes in the food web from fishing. On average, removing the grazers produced more algae than adding the fertilizer. Researchers at work in North Carolina.

“Our results provide rare large-scale confirmation of the importance of biodiversity to healthy ecosystems,” said Emmett Duffy, the study’s lead author and director of the Smithsonian’s Tennenbaum Marine Observatories Network. “It’s widely understood that controlling algal overgrowth of seagrasses requires reducing fertilizer runoff, but it turns out that maintaining diverse populations of the bugs and slugs that clean these underwater plants is just as important.”

Everything ZEN

The ZEN project is now in its second generation and has expanded to 25 institutions and more than 50 research sites from the Russian Arctic to Mexico and South Korea. Ongoing work by this collaborative team of more than 200 scientists and students seeks to understand how the diversity of seagrass animals and plants contributes to fish production, carbon storage and other ecosystem services.

“Honestly, its a new way of doing science for many of us,” said Jay Stachowicz, professor of Evolution and Ecology at UC Davis. “Ceding control of our experiments and data collection is hard for many of us who were trained to be fiercely independent. But the payoff is this kind of surprising result that none of us could have obtained on our own and a built-in consensus because we were all involved in each phase of the project.”

The study was published in Ecology Letters and supported by grants from the National Science Foundation and local support from the 15 partner institutions.