Female rats struggle to find their way in BPA study from MU and the NCTR/FDA
Cheryl Rosenfeld is one of 12 researchers partnering with the NCTR/FDA to study BPA
Despite concerns about bisphenol A (BPA), academic and regulatory scientists have yet to reach a consensus on BPA’s safety.
The National Institute of Environmental Health Sciences (NIEHS), the National Toxicology Program (NTP), the Food and Drug Administration and independent university researchers are working together to change that.
“The idea of this Consortium is to examine the potential systems that have been previously suggested to be affected by BPA,” said Cheryl Rosenfeld, an associate professor of biomedical sciences at the University of Missouri and one of twelve researchers involved in the project.
Rosenfeld’s group looked at spatial navigation learning and memory. They found that prenatal exposure to BPA could potentially hinder the ability of female rats to learn to find their way through a maze. This effect was not seen in male rats.
Approved by the FDA in the early 1960s, BPA can be found in a wide variety of products, including plastic food and drink containers with recycle codes 3 or 7, water and baby bottles, toys, the linings of metal cans and water pipes, even patient blood and urine samples.
BPA has structural similarities to estrogen and can potentially act as a weak estrogen in the body.
In Rosenfeld’s experiment, researchers at the National Center for Toxicology Research gave pregnant rats a fixed dose of BPA every day: a low, medium, or high dose.
After the baby rats were born, researchers continued to dose the babies, both male and female, according to what their mothers had received.
When these rats reached three months old, they were tested in a circular maze with twenty possible exit holes, one of which was designated as the correct escape hole. Every day for seven days, researchers tested the rats’ abilities to solve the maze in five minutes and timed them as they ran.
Rats solve mazes in three ways, Rosenfeld said.
They can run through the labyrinth in a spiral pattern, hugging the outer walls, and work their way in until they find the correct exit hole in what is called a serial search strategy.
Or they might move aimlessly in the maze using an indirect search strategy, Rosenfeld said. “In this case, the rats seemingly find the correct escape hole by random chance.”
Lastly, they can travel directly from the center of the maze to the correct escape hole. The third strategy is considered the most efficient method because the rats find their way swiftly, Rosenfeld said.
Sarah Johnson, a graduate student and first author on the paper, assessed each rat’s performance in the maze using a three-point tracking program that recognizes the rat’s nose, body, and tail.
Using the program, Johnson measured their performances in terms of the total distance traveled, the speed at which the rat ran the maze, how long it took the rats to solve the maze (latency), and how often the rat sniffed at an incorrect hole.
The last two parameters are considered the best gauges of spatial navigation learning and memory.
“What you expect to see is that they should start learning where that correct escape hole is,” Rosenfeld said. “Thus, their latency and sniffing incorrect holes should decrease over time.”
Rosenfeld’s group found that female rats that had been exposed to the highest dose of BPA since fetal development were less likely to find the escape hole than rats that hadn’t been exposed to BPA.
As for how this study may translate to people, Rosenfeld said, “the same brain regions control identical behaviors in rodents and humans.”
She considers it a starting point for setting up future experiments that take into consideration sex differences in cognitive behaviors and neurological responses to BPA.
Immediate next steps for the Rosenfeld group include analyzing tissue collected from the brains of rats that had undergone maze testing. Rosenfeld’s team of researchers will measure DNA methylation and RNA expression in the brain to determine which genes might be involved in navigational learning and memory. Their overarching goal is to determine how changes in observed sex- and dose-dependent behaviors occur on the molecular level.
NIEHS grant U01 ES020929 supported this research. Additional coauthors include Mark Ellersieck and Angela Javurek of the University of Missouri, Thomas H. Welsh Jr. of Texas A&M University, and Sherry Ferguson, Sherry Lewis, and Michelle Vanlandingham of the National Center of Toxicological Research/Food and Drug Administration. Read the full study on the Hormones and Behavior website and browse the supplementary data for this work.
This immunofluorescence picture shows the brain of an Alzheimer’s disease mouse model, also known as the TgCRND8 mouse. In the picture, the amyloid beta plaques are stained green and the microglia, or immune cells of the brain, are stained red. Image courtesy of Luke Woods.
By Caleb O’Brien | MU Bond Life Sciences Center
Jean Camden and Luke Woods have an ant’s-eye view of Alzheimer’s disease.
Both are bench scientists in the laboratory of Gary Weisman, a professor of biochemistry at the Bond Life Sciences Center. Jean has spent the past 12 of her 35 years at the University of Missouri in the Weisman lab, running experiments, managing the lab and working with students. Luke joined the Weisman lab six years ago, doing what he call’s the dirty work of science: “Gary does the writing and the NIH stuff, but down in the trenches — that’s me and Jean.”
Weisman’s lab studies Alzheimer’s and other diseases, so I sat down recently with Jean and Luke to talk about their research for Alzheimer’s & Brain Awareness Month.
Q: What does your lab do, and how does it involve Alzheimer’s?
Luke: We primarily have two projects. One, which has been a very longstanding project, is focused on salivary glands and salivary gland inflammation. The other is the Alzheimer’s project. The link between them is a particular type of cell surface receptor called a nucleotide receptor — more specifically, a P2 nucleotide receptor called P2Y2. These P2 receptors function in a lot of different ways, but the link is with inflammation: We look at P2 receptors in salivary gland inflammation and in Alzheimer’s disease, which has a very large inflammation component that often gets glossed over. In a lot of Alzheimer’s articles that the public reads, you hear about amyloid beta plaques and tau tangles and neurodegeneration, but a large component of that is inflammation, where some of the resident non-neurons in the brain start responding like there’s inflammation in the brain, and it actually kills neurons. That’s been the focus in Gary’s lab for the past 30-plus years.
JEAN: The P2 receptors — especially the P2X7 and P2Y2 which we focus on — Gary during his postdoctoral work started studying these receptors without really knowing that they existed. At the time, he just knew that there was a pore formed in cells caused by the addition of the nucleotide ATP which eventually leads to apoptosis (cell death). Eventually, we cloned the human P2Y2 receptor gene with another group in North Carolina, so we call it “our receptor.” It only appears in cells under inflammatory conditions, such as Alzheimer’s disease, salivary gland autoimmune disease and cardiovascular disease. Any time you have tissue damage, it looks like the P2Y2 receptor is up-regulated. And then once the damage is healed, the receptor goes away.
Inflammation is good — we want inflammation, that’s how we heal — it’s the chronic inflammation that’s bad. But we really don’t know how these receptors work and what their role is during chronic inflammation. Do we want to activate them, or do we want to inhibit them?
LUKE: Scientists have investigated P2X7 receptor antagonists in the treatment of Crohn’s disease and rheumatoid arthritis — there are several clinical trials that have been focused on these receptors, evaluating whether you want to block or activate them. If you block them, you prevent the acute inflammatory responses that are good for wound healing; if you activate them, you may extend those responses past the healing phase into a chronic inflammatory phase that can be quite damaging. So unraveling that fine line of what you want to be doing to these receptors in disease settings is sort of what we do here.
Jean Camden and Luke Woods look at images of a mouse brain with Alzheimer’s disease. // Photo by CALEB O’BRIEN/Bond LSC
Q: When I think of Alzheimer’s, I think of a shriveled, shrunken brain, but I associate inflammation with swelling. Why the difference?
LUKE: I think the distinction is acute versus chronic inflammation. With acute inflammation, you get swelling. The body has different types of immune responses: acute responders like neutrophils and macrophages are immune cells that act quickly. They come in, for example, if you have a scratch, and there can be swelling. Along with macrophages neutrophils can protect cells from bacteria. The macrophages can also clean up damaged tissue and then the repair cells go to work. Cells come in that lay down a new matrix, whereas undamaged cells then migrate onto the matrix and regenerate. Well, what happens after you’re done repairing is that there are signals that tell the inflammation to stop. In chronic inflammation, that’s where you have continued cell death, and the tissue would then shrivel up. The shriveled brain that you’re referring to is during chronic inflammation, and that’s an end-of-life case, after a very long bout with Alzheimer’s.
JEAN: What we think of as inflammation is often a cut or a wound. It’s only been in recent years that Alzheimer’s disease has been considered an inflammatory disease. We have a phenomenal immune system, but when it goes awry, you have problems. In the other disease we look at — an autoimmune disease — your immune system starts to attack your own body. It’s hard to treat and understand the underlying mechanism.
Q: So how are you trying to unravel the role of inflammation in Alzheimer’s?
JEAN: To study Alzheimer’s, we have an Alzheimer’s mouse model. It overexpresses a gene for the amyloid precursor protein that enables the brain to accumulate high amounts of beta-amyloid plaques that you always hear about. So we’re using this mouse model that we’ve crossed with a mouse that does not express any P2Y2 receptor, so it’s called a knockout mouse. The P2Y2 receptor knockout mouse by itself is fine, and the Alzheimer’s mouse does develop Ab plaques, but it lives to approximately 6 months old before it will develop behavioral defects. The interesting thing is that when we cross the P2Y2 receptor knockout mouse with the Alzheimer’s mouse, the offspring that are Alzheimer’s mice without P2Y2 receptors prematurely die. So at least in this Alzheimer’s mouse model, it looks like the presence of the P2Y2 receptor is protective, because without it, the Alzheimer’s mice die much earlier. But we don’t really know which cell type is most important: Is it the P2Y2 receptor up-regulated on neurons that acts to repair them —which we’ve already shown happens — or is it the P2Y2 receptor on microglia (an immune cell of the brain), or is it the P2Y2 receptor on blood vessels in the brain that help recruit immune cells from the cardiovascular system to help with repair?
So we’re using this mouse model to investigate the role of the P2Y2 receptor, plus we also use cell lines because we can easily control the environment for these cell lines in culture. We isolate primary neurons, we can prepare primary microglial cells or we can purchase cell lines that comprise blood vessels. We can then utilize these tools to investigate cell signaling mechanisms for the P2Y2 receptor in individual cell types.
LUKE: One of the findings that we have found interesting in these primary cells is when you take them fresh out of the mouse, put them in a dish and then treat them as you wish. We’ve shown that if you activate the P2Y2 receptor in primary microglia from the mouse, they will actually engulf and chew up beta-amyloid. And so one of the things we think might be happening in this Alzheimer’s mouse model is that P2Y2 receptor activation in these microglial immune cells in the brain is working to break down those beta-amyloid plaques. And when you lose the P2Y2 receptor in that mouse model, those plaques develop quicker because the immune cells are no longer offering protection by chewing up that beta-amyloid. That’s one of the hypotheses we’re exploring right now.
Q: So you’d bet that these receptors are actually protective against Alzheimer’s?
JEAN: Yes. Going back to the human — it’s hard to get human tissues, especially brain tissues, but there is one published study that has shown that in Alzheimer’s patients who have passed away the P2Y2 receptor is down-regulated, meaning there’s not much left. Which would make sense. If it’s down-regulated, the plaques aren’t able to be chewed up, per se, by these microglia. There’s a correlation between low levels of P2Y2 receptors and Alzheimer’s disease that is apparent at the end of life.
LUKE: It’s very difficult to do some of these studies in humans because most of the available Alzheimer’s tissues are from end of life cases where you can only look at the end result of the disease without looking at the progression of the disease. Obviously you can’t take brain tissue from a living person, so the ability to study live cells from Alzheimer’s patients is limited. We rely very heavily on mouse models.
This immunofluorescence picture shows microglia cells that were isolated from the brain of an Alzheimer’s mouse model called TgCRND8 and cultured in a dish for further analysis. Image courtesy of Luke Woods.
Q: What have been the biggest shifts in our understanding of Alzheimer’s in recent years?
LUKE: Maybe one shift — I may not be the best expert to speak about it — is the idea that the beta-amyloid plaques are the cause of disease. It is now being mostly recognized that they’re really the tombstones of the disease. They’re not the initial cause, but rather the end result of the disease. For a long time investigators were focused on trying to prevent the buildup of beta-amyloid because that was one aspect of Alzheimer’s disease that you could see and measure. Now the thinking is that maybe the beta-amyloid does not contribute as much to disease progression as originally thought, and rather is the end result of a complicated mechanism that is actually causing the neurodegeneration.
JEAN: There’s still debate on what causes Alzheimer’s disease. There is a small percentage of patients where it’s actually related to a genetic alteration in the amyloid precursor protein gene.
LUKE: Another link has been with the ApoE (apolipoprotein E) gene, which makes a lipoprotein and cholesterol transporter. We inherit 1 copy of the ApoE gene from each of our parents and it has been shown that individuals who have at least 1 copy of a particular variant of the gene called ApoE4 are at increased risk of developing Alzheimer’s disease.
Q: From the perspective of a lab scientist, why do you care about Alzheimer’s?
JEAN: We care about any disease, really, and if we can show that our receptors have anything to do with any disease, we’d be proud to have a role in that.
LUKE: We don’t do much clinical science here, it’s mostly basic science. We contribute to the basic understanding of the disease so that drug companies and medicinal chemists who develop drugs for clinical use in Alzheimer’s patients can say, “Hey, this group’s research found a new mechanism related to Alzheimer’s disease, so let’s target this pathway to treat the disease.” It’s always nice to contribute to that sort of ground-level science.
JEAN: That would be the ideal, to show that whether you have to activate or inhibit the P2Y2 receptor, it does something to improve the clinical outcome in Alzheimer’s patients. A better understanding of Alzheimer’s and other diseases is what’s needed — we’re just working to provide a piece of the puzzle.
Q: How has being down in the trenches changed your perspective on research and Alzheimer’sin general?
JEAN: We’re the ones who are hoping to clarify the direction for science to go. We do the experiments and we are the first ones to see the data. We collect the data that becomes the cornerstone for deciding the direction our research goes. I think Gary would agree with that — he depends on us a lot to collect the data and we depend on him to help determine which scientific findings to chase and which ones not to chase.
I’ve been doing this for 35 years, and I really do enjoy the science. I’ve seen the science of these nucleotide receptors come a long way. These receptors have in common their use of extracellular nucleotides, particularly ATP (or adenosine triphosphate, more commonly known as the intracellular high energy molecule of all cells). And this ATP, is at a high concentration inside cells, so when it is released by cell damage, it can easily activate nucleotide receptors on nearby cells. It was Dr. Geoffrey Burnstock, now considered to be the grandfather of nucleotide receptors, who claimed a long time ago that there are receptors on the outside of cells that respond to ATP. Everybody kind of laughed at him, “Yeah, sure, right. There’s no way: ATP belongs inside the cell.” So for me personally, to come in on the ground level for these receptors and find a role for them in a variety of diseases has been exciting for me.
LUKE: ATP is the energy currency inside of all cells, so it’s use outside cells would be like tossing money out the window. Why would they want ATP outside the cell? It didn’t make any sense at the time, but looking back I think it does. What happens if you damage or rupture a bunch of cells during an injury? You get the release of a high concentration of ATP that neighboring cells recognize as a danger signal telling them that an injury has occurred. In that sense, ATP makes the perfect signaling molecule to tell other cells that an injury has occurred and they need to start the repair work by recruiting immune cells to the damaged tissue.
Jean Camden has spent 35 years working at the University of Missouri and more than a decade in Gary Weisman’s lab. // Photo by CALEB O’BRIEN/Bond LSC
Q: Where would you like to be in five years with this research?
JEAN: I talked about determining how the P2Y2 receptor in this mouse model was protective. It would be nice to find out which cell type on which the P2Y2 receptor is expressed in contributes most to neuroprotection. Our hypothesis would be that the microglial cells are very important, since they gobble up beta-amyloid, but other cell types including neurons and endothelial cells are likely involved. We’re also anxious to look at other inflammatory diseases to see if the P2Y2 receptor plays a similar role there.
LUKE: From somebody who does a lot of bench work, something I would like to see is a really good tool, a specific agonist or antagonist of the P2Y2 receptor that could be used in the clinic. There are a few suitable compounds available that we use to investigate the P2X7 receptor— I’ve told you that some have been tested in clinical trials — but the P2Y2 receptor has been sort of an enigma, due to the lack of selective inhibitors and agonists that are specific enough for clinical use. I’d like to see the development of a specific agonist or antagonist that could eventually be used to treat inflammatory diseases. There’s no reliable drug that is currently suitable to investigate the P2Y2 receptor in animals or humans, so clearly more work is needed there.
This interview has been edited for length and clarity.
Bond LSC researchers showed for the first time ever that a grass, Setaria viridis, can receive 100 percent of its nitrogen needs from bacteria when associated with plant root surfaces. This grass will now serve as model for research into biological nitrogen fixation that could benefit crop development. | Photo by Roger Meissen, Bond LSC
By Roger Meissen | MU Bond Life Sciences Center
As farmers spend billions of dollars spreading nitrogen on their fields this spring, researchers at the University of Missouri are working toward less reliance on the fertilizer.
Less dependence on nitrogen could start with a simple type of grass, Setaria viridis, and its relationship with bacteria. The plant promises to lay groundwork for scientists exploring the relationship between crops and the fixing nitrogen bacteria that provide them the nitrogen amount plants need daily.
“In science sometimes you have to believe because we often work with such small microorganisms and DNA that you cannot see,” said Fernanda Amaral, coauthor and MU postdoctoral fellow at Bond Life Sciences Center. “Before this research no one had actually proved such evidence that nitrogen excreted by bacteria could be incorporated into plants like this.”
Fernanda Amaral, coauthor and MU postdoctoral fellow at Bond Life Sciences Center. | Photo by Roger Meissen, Bond LSC
Biological Nitrogen fixation — where diazotrophic bacteria fix atmospheric nitrogen and convert it to ammonium — provides a free way for plants to alter and absorb the nutrient. Farmers have long known that legumes like soybean fix nitrogen due to the symbiosis with bacteria in the soil through development of nodules on their roots, but since grasses like corn and rice don’t form this specialized structures that relationship has been trickier to explore.
Yet in fact, this team’s experiments showed the grass Setaria viridis received 100 percent of its nitrogen needs from the bacteria Azospirillum brasilense when associated with plant root surfaces.
“I believed in these bacteria’s ability, but I was really surprised that the amount of nitrogen fixed by the bacteria was 100 percent,” Amaral said. “That’s really cool, and that nitrogen can make so much of a difference in the plant.”
Worldwide farmers used more than 100 million tons of nitrogen on fields in 2011, according to the United Nations Food and Agriculture Organization. In the same year, the U.S. alone produced and imported more than $37 billion in nitrogen.
This grass can serve as a simple model for research, standing in for grass relatives such as corn, rice and sugarcane to explore a similar relationship in those crops. This research, “Robust biological nitrogen fixation in a model grass–bacterial association,” was published in the March 2015 issue of The Plant Journal.
A nutrient, a nuclear reactor and a model plant
Proving that this grass actually uses nitrogen excreted from the bacteria took some clever experiments, a global collaboration and a nuclear reactor.
MU researchers in the lab of Gary Stacey, a Bond LSC investigator, partnered with scientists in Brazil and at Brookhaven National Laboratory in New York to find a robust plant model system.
They screened more than 30 genotypes of Setaria viridis grass, looking for a strong nitrogen fixing response when colonized with three different bacteria strains. They germinated the seeds in Petri dishes and inoculated those three days after germination with a bacterial solution. Then plants were transplanted into soil containing no nutrients. By eliminating nitrogen in the soil, the scientists were able to make sure that the bacteria was the only source of nitrogen for plant.
The team settled on Azospirillum brasilense bacteria, which has been used commercially in South America to improve crop plant growth. It colonizes the surface of the roots and showed the greatest amount of plant growth when associated with plant roots.
Proving that the bacteria truly fixed the nitrogen used by the plant, required exposing plants to radioactive isotopes at Brookhaven National Laboratory. That began with Nitrogen 13, an unstable radio isotope that showed exactly where and how quickly this nutrient was taken up from the bacteria.
A radio tracer chamber at Brookhaven National Laboratory was needed to test if Setaria viridis actually used nitrogen produced by the bacteria. The scientists allowed only one leaf to contact the radioactive nitrogen, so they could truly tell if it was being used. | Photo provided by Fernanda Amaral
“Nitrogen 13 is really sensitive matter with a half-life of less than 10 minutes, and we first thought there wouldn’t be that much nitrogen fixed by the plant,” Amaral said. “We administered Nitrogen 13 only on the roots, quickly scanned the samples and calculated how much of the nitrogen the plants assimilated based on the decay analysis of the tracer.”
This experiment, paired with several others, showed that this model grass truly incorporated the nitrogen released by the bacteria and metabolizes it in several components.
Model (plant) citizen
But why does a type of grass that doesn’t produce food matter so much?
The answer is time and simplicity.
“Corn is really good at responding to bacterial inoculation, but it’s very big and takes a long time to produce seeds and also the genome is complex,” said Beverly Agtuca, an MU Ph.D. student who worked on the study. “Setaria viridis is a small plant that can produce a lot of seeds faster, has a pretty simple genome and can serve as a model for research.”
That makes it perfect to explore how the plant actually uses its bacterial partners, and labs around the world are already using this plant model for research.
For the Stacey lab, the next step is to pinpoint the gene in the model grass that makes this possible.
“We want to identify the genes responsible for the interaction between plant and bacteria and meanly the ones involved with the nitrogen uptake,” Fernanda said. “We hope that will allow us to improve plant growth based on the gene to further study.” We believe that our findings can stimulate others studies at this area, which seems to be a promise plant friendly way to apply for promoting a sustainable agriculture, especially to crop systems including bioenergy grass.
Amaral and Agtuca work in the lab of Gary Stacey at Bond LSC. Stacey is a Bond LSC investigator and a Curators Professor of Plant Sciences in the College of Agriculture, Food and Natural Resources at the University of Missouri. Collaborators included researchers at Brookhaven National Laboratory, State University of New York, Federal University of Paraná in Brazil and Federal University of Santa Catarina in Brazil.
Funding for this project came from the National Institute of Science and Technology- Biological Nitrogen Fixation, INCT-FBN, the Brazilian Research Council, Ciência Sem Fronteiras Program, The Department of Energy and SUNY School of Environmental Science and Forestry Honors Internship Program.
The environmental build-up of bisphenol A (BPA) can result in a life-changing shift for aquatic animals.
For painted turtles, exposure to this chemical can disrupt sexual differentiation, according to new research in General and Comparative Endocrinology.
Scientists at the University of Missouri have teamed up to show how low levels of certain endocrine disruptors like BPA can cause males to possess female gonadal structures in newly-hatched turtles. This collaboration between MU, Westminster College, the U.S. Geological Survey (USGS) and the Saint Louis Zoo exposed turtle eggs to levels of BPA similar to those currently found in the environment.
“It’s important because this is one of the first times we’ve seen low doses of BPA causing disorganization or reorganization of the male gonad to resemble females,” said Dawn Holliday, adjunct assistant professor of pathology & anatomical sciences at MU’s School of Medicine and assistant professor of biology at Westminster College. “We’re not sure what this means in terms of population-level effects, but certainly it can cause some reproductive dysfunction for turtles.”
Endocrine disruptors leach into rivers and streams and concern scientists because of potential effects on animals and humans. While BPA is used as a hardening agent in plastics, it also is used to line cans and in manufacturing where more than 15 billion tons are produced each year.
In the case of painted turtles, these chemicals have potential to alter sex ratios, which are normally regulated by temperature during incubation. Eggs exposed to cooler temperatures normally produce males and those hatched at warmer temperatures produce females.
In this experiment, turtle eggs were incubated at temperatures known to rear males and dosed with low, medium and high levels of BPA. BPA-exposed turtles were compared to hatchlings not exposed to chemicals as well as a group exposed to high levels of ethinyl estradiol — an endocrine disruptor found in birth control — at the USGS Columbia Environmental Research Center.
These doses resulted in turtle sex organs that should have been male , but abnormally contained female gonadal elements. The low dose represented BPA concentrations found in fields where turtles can nest while the mid and high doses approximate BPA levels near contaminated sites like landfills.
“We exposed the eggs for a limited amount of time right when they were most vulnerable to the effects,” said Cheryl Rosenfeld, a researcher at MU’s Bond Life Sciences Center and an associate professor of biomedical sciences in the College of Veterinary Medicine. “We found that we got partial feminization in more than 30 percent of turtle eggs exposed to BPA despite being incubated at male-permissive temperatures.”
These results give the team a look into what real-world exposure levels might mean in the wild and a starting point for comparison.
“Turtles are the most endangered vertebrate taxa and they have all sorts of conservation issues coming at them from people harvesting them to disease, and endocrine disruptors are another potentially big whammy they have against their conservation status,” said Sharon Deem, director of the Saint Louis Zoo’s Institute for Conservation Medicine. “This research is a stepping stone, and we are hoping we can apply these results to populations of turtles throughout the state and use these results as a marker to look at endocrine disruptors in the wild.”
Future studies plan to look at the underlying mechanisms behind sexual disruption and will extend the study to animals including fish and mammals. Rosenfeld’s laboratory is in the process of examining how early exposure of turtles to endocrine disruptors might affect cognitive behaviors, including spatial navigation ability.
Fred vom Saal, Curators Professor of Biological Sciences in the College of Arts and Science at MU, Don Tillitt, an adjunct professor of biological sciences at MU and a research toxicologist with the USGS, Ramji Bhandari, an assistant research professor of biological sciences and a visiting scientist with the USGS at MU and Caitlin Jandegian, a senior research technician at MU, all collaborated on the study.
Funding was provided by Mizzou Advantage, an MU initiative that fosters interdisciplinary collaboration among faculty, staff, students and external partners to solve real-world problems in four areas of strength identified at the University of Missouri. These areas include Food for the Future, Sustainable Energy, Media for the Future and One Health/One Medicine.
A simple virtue lies at the heart of Xuemin (Sam) Wang’s research: thrift.
“A good way to think of it is how to increase output without demanding more inputs,” Wang said.
Wang, the E. Desmond Lee and Family Fund endowed professor at the University of Missouri-St. Louis and a principal investigator at the Donald Danforth Plant Science Center, studies plant membrane lipids. His lab is focused on understanding the relationship between oil production and plant stresses such as drought and nutrient deficiency.
Wang will speak during the 31st annual Missouri Life Sciences Week, a yearly celebration of MU’s research and an exploration of public policy, entrepreneurship and science outreach.
Wang’s lab uses Arabidopsis, the lab mouse of the plant world, as a discovery tool but also works with crops such as soybean and the Camelina species. Camelina was widely grown in Europe before it was supplanted by canola, but Wang and others are working to develop Camelina as a productive oil crop.
The lab studies how lipids — the fatty acids that make up cell membranes — help regulate cell function. For example, they’re trying to figure out how a cell senses water and nutrients and then “determines whether it should grow faster or store more lipid or carbohydrates,” Wang said.
By understanding those processes, future research might develop plants that do more with less. That could mean less water and chemical fertilizer needed for the same or greater yield. Wang pointed to reliance on fertilizers as a major problem.
“Not only does it drive up agriculture production costs, but there can be major environmental consequences.”
Ultimately, Wang’s research could improve plant oil and biomass production while decreasing our dependence on fertilizers and abundant water.
Wang’s presentation on “Lipids as Molecular Switches in plant stress signaling and metabolic integration” constitutes this year’s Charles W. Gehrke distinguished lecture. Gehrke, a MU professor of Biochemistry who died in 2009, was instrumental in advancing the field of chromatography and helped analyze rock samples retrieved from the moon during the Apollo 11 mission. Gehrke grew up in poverty during the great depression and worked in melon fields during his youth before studying at Ohio State University.
Missouri Life Sciences Week is an annual event. In addition to Wang’s talk, this year’s line-up will also focus on HIV and emerging diseases and highlight more than 300 undergraduate and graduate research projects at its poster sessions.
Roger Meissen/Bond Life Sciences Center – These soybean roots show some nematode cysts. The small, white circles are the hardened body of the nematodes and form when the nematode attaches itself to the root to create a feeding cell.
Beneath a North Carolina field in 1954, a tiny worm inched its way through the soil and butted against a soybean root. The worm pierced the plant, slipped inside and inserted a needle-like appendage into a cell. It pumped a mixture of proteins into the root cell and waited for the potent blend to take effect on the unsuspecting soybean.
Since the first detection of soybean cyst nematode (SCN) in the US, the worm Heterodera glycines has spread to about 80 percent of American soybean fields. In Missouri, SCN attacks soybeans in almost every county and causes decreased yields even in robust, healthy-looking fields. Nationwide, SCN wreaks havoc to the tune of $1.2 billion per year, making it by far the most costly soybean pest.
Despite the hefty toll, farmers still depend on the same small handful of resistant soybean varieties to combat SCN that they have used for years. But those natural defenses are becoming less effective as nematodes evolve.
“More than 90 percent of the soybean cultivars that farmers plant derive their resistance from a single source,” said Melissa Mitchum, a plant nematologist at the University of Missouri Bond Life Sciences Center and Division of Plant Sciences faculty member in the College of Agriculture, Food and Natural Resources. “Consequently, this has led to widespread virulence in the pathogen population, thereby reducing the effectiveness of those resistant cultivars.”
But in the past 10 years, researchers studying SCN have made numerous breakthroughs, unlocking the secrets of the nematode and exploring how the worm interacts with host plants. Now, scientists are poised to bring that knowledge from the laboratory to the field.
Found in translation
Relatively little was known about SCN a decade ago.
Scientists could determine the type of nematode in a soil sample and had just figured out the cocktail of proteins a nematode pumps into the soy root cell that transform it into a syncytium, or feeding cell.
Working in part with funding from commodity boards and farmer checkoff dollars, researchers around the country made breakthrough after breakthrough, deepening our understanding of SCN and equipping scientists with new tools to fight the pest.
That money helped scientists sequence the soybean genome, draft a SCN genome and pinpoint important soy and SCN genes.
Checkoff investments continued to pay dividends in 2012 when Mitchum and colleagues cloned the first gene linked to natural soybean cyst nematode resistance. This breakthrough is one key step in moving science from the laboratory into the field. With a SCN resistance gene in hand, new avenues for creating soybean varieties that fight off the nematode are opening up.
But other areas of research also hold promise in the struggle against soybean cyst nematode’s parasitic ways.
Mitchum’s group also identified the plant receptors that recognize and respond to the blend of proteins an attacking nematode inserts into a plant. In a recent project published in Plant Biotechnology Journal, Xiaoli Guo, a postdoctoral fellow in Mitchum’s lab demonstrated that silencing those receptors in soybean roots helped the plant resist SCN.
This work has implications for more crops than just soybeans: Working with collaborator Xiaohong Wang at Cornell, Mitchum’s group used their understanding of plant receptors to develop a potato resistant to potato cyst nematode.
A roadmap for discovery
To build on the momentum of recent research, experts drafted a roadmap for the next decade of nematode research. Their goal, Mitchum said, is to address the challenge of translating these research breakthroughs into something tangible for the farmer.
With support from state farmer run organizations such as the Missouri Soybean Merchandising Council, the North Central Soybean Research Program and the United Soybean Board, researchers are formulating teams that “bring together commodity, industry and university funding to develop collaborative, interdisciplinary, multistate projects,” said Mitchum.
And there’s plenty of scientific firepower to advance research: MU’s College of Agriculture, Food and Natural Resources alone has more than 90 faculty studying plant science, plant genetics and other areas of agriculture-related science.
The scientists’ plan for the next 10 years involves a blend of molecular research, plant breeding, population biology and outreach. Researchers will focus on refining the existing draft SCN genome, which will help to develop a quick, inexpensive test for HG type and eventually contribute to understanding of how SCN overcomes a plant’s resistance. They’ll create an “atlas” of SCN genes researchers can use to block the pest. Updating yield loss estimates and mapping SCN distribution will also give scientists a better idea of the nematode’s national impact. Other efforts will allow breeders to incorporate new sources of resistance into commercially-available varieties, refine the use of non-host species to control SCN and develop a pipeline for creating and testing transgenic SCN-resistant soybeans. Finally, videos, webinars and training modules will help scientists, students and producers take advantage of new discoveries and techniques.
Roger Meissen/Bond Life Sciences Center – Michael Gardner, Ph.D. student, Melissa Mitchum, associate professor of Plant Sciences, Xiaoli Guo, post doctoral fellow, conduct research at the University of Missouri. They investigate how soybean cyst nematode overcomes soybean resistance to identify novel approaches for management.
Onward with research
A thorough understanding of SCN resistance and virulence starts with basic research and then moves into the field. “We all need to come together to transfer this knowledge to the breeder,” Mitchum said, “and from there it gets out to the farmer.”
Her lab recently received a National Science Foundation grant to continue their work on soybean protein receptors. Specific targeting of the receptors is just one potential strategy for producing new kinds of SCN-resistant plants. A second grant, from the National Institute of Food and Agriculture, will allow the lab to continue refining their understanding of how SCN proteins overcome a host plant’s defenses. To that end, Mitchum’s graduate student Michael Gardner is identifying the genetic blueprint of the different SCN types present in Missouri fields.
“If we better understand nematode populations and what makes those populations distinct, we can better advise farmers confronted with virulent nematodes,” Gardner said. “We’ll be able to go one step beyond the HG type test and understand how nematodes are able to adapt in the long term, not just the next growing season.”
But these breakthroughs do little good unless they then become useful tools for breeders and ultimately farmers. To that end, Mitchum and other researchers will help breeders use research results to produce soybeans with durable resistance. They‘ll also develop guides so farmers can easily incorporate new technologies and management strategies into their farms.
It’s important for farmers, breeders and researchers to take a unified approach to fighting SCN, Mitchum said, because a tactic that seems successful at first could backfire.
For instance, combining resistance genes in a single soybean variety could actually be harmful. “When we deploy it in the field, we select for nematodes that can overcome multiple types of resistance,” Mitchum said.
A better approach might be to perfect varieties with distinctive resistance mechanisms and insure durable resistance by rotating among the resistant varieties and non-host crops.
“It’s similar to taking antibiotics,” Mitchum said. “Improper use and overuse selects for resistance.” The strategic planning document should help everyone working with soybeans and SCN leverage and build upon new knowledge.
Despite all the research and recent breakthroughs, there remains only one certainty in the ongoing arms race between soybeans and SCN: “It is highly unlikely that we will eradicate it.” Mitchum said, “We’re going to have to find new strategies to protect and bolster soybean yields.”
Thanks to the efforts of researchers such as Mitchum, in the future SCN might be a little easier to get along with.
Roger Meissen/Bond Life Sciences Center – Research specialist and coordinator for the Plant Nematology Lab Amanda Howland processes soil samples for nematodes. Howland replaced Bob Heinz earlier this year.
University of Missouri Plant Nematology Laboratory: An extensive legacy
Bob Heinz spent his last day at work in December surrounded by nematodes. Heinz served as Mitchum’s research specialist and coordinator of the Plant Nematology Laboratory, where he processed soil samples, responded to growers and assisted researchers. After 35 years on the job, he’s retired, and Amanda Howland is now filling his shoes. The scientists and farmers who’ve worked with Bob over the decades thank him for his dedication and wish him luck in his retirement. And Amanda: Welcome aboard.
The Plant Nematology Lab, housed within Mitchum’s lab at MU, represents a successful model for how research, teaching and extension program integration can promote interdisciplinary collaboration. Such an approach helps maintain an effective pipeline that brings research-based information and resources from MU to Missourians. The lab offers an array of tests that help farmers understand and manage nematode populations. The available tests include:
–Vermiform Nematode Identification: Soybean Cyst? Root Knot? Lesion? Find out what kinds of nematodes are in your fields with this test.
–Soybean Cyst Nematode Egg Count: This procedure provides an estimate of the number of SCN eggs in your field.
–Soybean Cyst Nematode HG Type Test: Different types of SCN have overcome various sources of soybean resistance. A HG type test will help you determine the best source of resistance for the particular type of SCN in your field.
That can depend on their parents’ genes, according Oliver Rando, an epigeneticist at the University of Massachusetts.
Rando will speak Saturday, March 14, at 10:30 a.m. at the 11th Annual Life Sciences and Society Program at Bond LSC. His research focuses on how fathers’ lifestyles affect their children, one part of the symposium’s focus on epigenetics. Epigenetics is the study of how organisms change because of a modification in gene expression.
Rando is clear that his research is no more important than that of other scientists in his field.
“The field we work in is important since we and others have shown that a father’s lifestyle can potentially affect disease risk and other aspects of his children,” he said.
During his talk on Saturday, Rando will discuss a “paternal effect paradigm” based on experiments his lab conducted on male mice. The mice were fed different diets and mated with control females. Then researchers analyzed the metabolic effects that resulted in their offspring.
“In terms of the basic science aspects of the system, doing this sort of experiment with fathers rather than mothers is important, since mothers provide both an egg and a uterus to the child, whereas in many cases fathers only provide sperm,” Rando said. “So, with fathers you don’t have as many things to look at to find where the relevant information is.”
Scientists in his lab also study yeast and worms to understand epigenetic inheritance. They use molecular biology, genetic and genome-wide techniques to conduct the research.
Adeno-associated virus type 2 at 3.0 A (xie, et al, Proc Natl Acad Sci U S A. 2002; 99:10405-10.) Courtesy David Pintel
It’s an understatement to say viruses are small.
But an average virus dwarfs the diminutive variety known as parvoviruses, which are among the most minuscule pathogens known to science.
Tucked inside a protective protein shell, or capsid, parvoviruses contain a single DNA strand of about 5,000 nucleotides. If parvo’s genetic material is like an hour-long stroll around your neighborhood, a bigger virus like herpes is equivalent to walking from St. Louis to Columbia, Missouri.
Dr. David Pintel stands next to a scan in his lab in Bond Life Sciences Center on Tuesday, Feb. 3, 2015. Hannah Baldwin/Bond LSC.
“I joke that we can do the whole parvovirus genome project in an afternoon, because it’s just taking it downstairs and having it sequenced,” said David Pintel, a Bond Life Sciences Center virologist and Dr. R. Phillip and Diane Acuff endowed professor in medical research at the University of Missouri. “It’s the size of one gene in the mammalian chromosome.”
But that little stretch of DNA still has plenty of tricks up its sleeve.
Pintel has spent nearly 35 years studying parvo and is one of the world’s foremost experts on the virus, but he’s still plumbing the tiny pathogen’s depths.
His lab focuses on unraveling how parvo interferes with a host cell’s lifecycle and understanding the virus’ quirky RNA processing strategies.
“Even though the virus is small, it’s not simple,” David Pintel said. “Otherwise we’d be out of business.”
Over the last two decades, parvo has become an important tool for gene therapy, an experimental technique that fights a disease by inactivating or replacing the genes that cause it. Researchers enlist a kind of parvovirus known as adeno-associated virus as a gene therapy vector, the vehicle that delivers a new gene to a cell’s nucleus. Pintel helped suss out the virus’ basic biology, an important step for developing effective gene therapy.
A varied virus
The name ‘parvo’ comes from the Latin word for ‘small.’ But the virus’ size makes it a resourceful, versatile enemy and a valuable model for understanding viruses and how they interact with hosts.
Parvoviruses fall into five main groups. They infect a broad swath of animal species from mammals such as humans and mice to invertebrates such as insects, crabs and shrimp.
Canine Parvovirus at 2.9 A (Tsao, et al, Science. 1991; 251:1456-65.) Courtesy David Pintel.
Canine parvovirus, or CPV, is perhaps the best-known type.
It targets the rapidly dividing cells in a dog’s gastrointestinal tract and causes lethargy, vomiting, extreme diarrhea and sometimes death. In humans, Fifth disease, caused by parvovirus B19, is the most common. This relatively innocuous virus usually infects children and causes cold-like symptoms followed by a “slapped cheek” rash. There is no vaccine for Fifth disease, but infections typically resolve without intervention.
Reading the transcript
Pintel surveyed the whole parvo family to understand its idiosyncrasies.
To study bocavirus – a kind of parvo recently linked to a human disease – Pintel looked closely at the dog version, minute virus of canines (MVC). MCV serves as a good model for the human disease-causing virus. While examining MVC, he noticed an unexpected signal in the center of the viral genome. The signal terminates RNA encoding proteins for the virus’ shell, a vital part of the pathogen.
Finding such a misplaced signal in the middle of a stretch of RNA is like coming across a paragraph break in the middle of a sentence.
Pintel knew the virus bypassed this stop sign somehow, because the blueprint for the viral capsid lies further down the genome.
To overcome this stop sign, this particular parvovirus makes a protein found in no other virus. The protein performs double-duty for the virus: It suppresses the internal termination signal and splices together two introns, or segments of RNA that do not directly code information but whose removal is necessary for protein production. Splicing the introns together ensures that the gene responsible for producing the viral capsid is interpreted correctly.
Viruses and hosts: a game of cat and mouse
The conflict between a virus and a host is a constantly escalating battle of assault and deception.
Viruses need a host cell’s infrastructure to replicate, but have to fool or outmaneuver its defenses.
Pintel discovered one example of this trickery in mice, where parvo triggers a cellular onslaught known as the DNA damage response, or DDR. This type of parvo co-opts that defense. Normally DDR pauses the cell cycle to keep damaged DNA from being passed on to the next generation of cells, but parvo exploits that delay, buying time for the virus to multiply.
“For many, many hours the cells are just held there by the virus while the virus continues to replicate,” Pintel said. “And then that cell never survives; the virus kills the cell. It’s that holding of the cell cycle — which is part of the DNA damage response — that the virus hijacks to hold the cell cycle. It’s really cool.”
Parvo’s small size makes it especially beholden to their hosts. But that can make them particularly revelatory for researchers.
Parvovirus samples from an experiment labeled by Femi Fasina, a postdoc in Pintel’s lab. Caleb O’Brien/Bond LSC.
“It’s a twofold thing,” Pintel said, “Because it’s a virus that’s dependent on the cell, when you learn how the virus is doing these things, you learn how the cell does those basic processes. If we’re looking at a viral-cell interaction, yes, we’re looking at it from a viral point of view, but on the other hand we’re trying to understand the basic cellular process.”
Uncovering such nuanced interactions is a painstaking, laborious process that often goes unheralded by mass media. But those fundamental discoveries provide the building blocks upon which other researchers depend, said Femi Fasina, a postdoc in Pintel’s lab.
“When you understand basic biology, people can walk on those advancements. Although we don’t see the impact immediately, such things lead to breakthroughs that will revolutionize a lot of things.”
A small question
Despite his deepening understanding of how parvo works, there remains one debate about the virus that Pintel deems beyond the scope of his research: Are the tiny slivers of DNA that comprise parvoviruses even alive?
“I think that’s a crazy question,” he said. “It’s semantics. The virus is a genome. It goes into a cell, it doesn’t do anything until it’s inside of a cell and then it does stuff.” So whether you write parvoviruses into the book of life depends entirely on how you define the word ‘alive.’
“I put that in the realm of philosophy,” Pintel said, “not the realm of science.”
Mutant arabidopsis models under lamps in Shuqun Zhang's lab.
Three-month-old mutant arabidopsis models are used to study the function of pollen.
The thought of pollen dispersed throughout the air might trigger horrific memories of allergies, but the drifting dander is absolutely essential to all life.
Science has long linked this element of reproduction with environmental conditions, but the reasons why and how pollen functions were less understood. Now lingering questions about the nuanced control of plants are being answered.
“Pollen is a very important part of the reproductive process and if we understand how pollen develops and how environmental stresses impinge on this process, we might be able to prevent crop loss due to high temperature or drought stress etc.,” said Shuqun Zhang, a Bond Life Sciences Center investigator.
Zhang has developed a new line of seeds that helped him and his lab identify an influential signaling pathway that triggers a chain reaction associated with normal pollen formation and function.
This research could lead to improvement to a plant’s response to disastrous environmental variables like drought to optimize pollen production and increase the production of food crops.
Left: Pollen grains genotypes MAPK3 and MAPK6 are illuminated by red and yellow dye using a fluorescent microscope. RIGHT: Normally developed pollen grains shown by an electronic microscope scan. | Credit: Shuqun Zhang
Seeds of success
Mutant seeds are the key to this work.
Instead of glowing green in the soil like you might see in a science fiction movie, they are providing important insight on plant reproduction and stress tolerance.
Zhang developed these plants from a mutant strain of Arabidopsis, a model plant used in scientific research. Certain genes were “switched off”to pinpoint where important pollen functions were signaled.
Using this mutant plant and seed system, Zhang found that WRKY34and WRKY2, two proteins that turn on/off genes, are regulated by MPK3and MPK6 “signaling” enzymes. These enzymes basically transform proteins from a non-functional state to a functional state, turning on specific duties or functions. Zhang, a professor of biochemistry at MU, began tinkering with the MPK3 and MKP6 pathways more than twenty years ago during his post-doc at Rutgers University.
Zhang’s research shows the newly identified MPK3/MPK6-WRKY34/WRKY2 pathway is a key switch in the hierarchy of the signaling system in pollen formation.
The research showed that the plant’s defense/stress response and reproductive process are linked, and the influential proteins MPK3 and MPK6 were part of the bigger WRKY34/WRKY2control pathway, which is activated in early pollen production.
The system is so useful that researchers across the country won’t stop asking for the seeds, Zhang said.
“We have a lot of requests for seeds,” Zhang said. “This is a very nice system to study pollen formation and function.”
The cascade of control
The functions of MPK3/MPK6 in plants can be compared to a “mother board” switch. The pathway — MPK3 and MPK6 —are part of a hierarchy of response, turning functions on or off. In other words, it’s a switch that controls a lot of different things. Controlling WRKY34/WRKY2 is one of the many roles played by MPK3 and MPK6.
Shuqun Zhang, University of Missouri Bond Life Sciences investigator.
“Whatever is plugged into it is what comes on,” Zhang said. “We are actually very, very interested in the evolutionarily context, how this came to be.”
This signaling process is just one of many in plants. MPK3 and MPK6 are two out the 20 MPKs, or MAPKs (abbreviated from Mitogen-Activated Protein Kinases) in Arabidopsis. They control plant defense, stress tolerance, growth, and development including pollen formation and functions.
“We determined that this MAPK-WRKY signaling module functions at the early stage of pollen development,” Zhang said.
The “loss of function of this pathway reduces pollen viability, and the surviving pollen has poor germination and reduced pollen tube growth, all of which reduce the transmission rate of the mutant pollen,” according to the research.
Zhang and his lab worked with the MU Division of Biochemistry and Interdisciplinary Plant Group on the research, which published in PLoS Genetics in June of this year.
A world without pollen production and defense
Without pollen, plants would not reproduce — there aren’t any Single Bars in the plant world (that we know of) — and if plant generations don’t propagate, there would be no air or food for human life to sustain.
“The factors such as heat and drought stresses cause problems to the plant’s normal developmental process and that’s how pollen fails to develop,” Zhang said. “If we understand the process, and know how environmental factors impact negatively the process, we can then make plants that can handle environmental stress better.”
Zhang and his lab continue to research the complexities of these pathways. Next on the quest is to answer how MPK3/MPK6 are involved in pollen functions such as guiding the pollen tube growth towards ovule to complete the sexual reproduction process in plants.
“It is possible that MPK3 and MPK6 are activated quickly in response to the guidance signals,” he said. “There’s still a long way to go because very few players in this process have been identified, we try to understand the biological process how they work together.” This research is in collaboration with Dr. Bruce McClure, also professor of Division of Biochemistry.
Read more:
1. PLoS Genetics (May 2014): Phosphorylation of a WRKY Transcription Factor by MAPKs is Required for Pollen Development and Function in Arabidopsis — Funded by a Hughes Research Fellowship and grants from the National Science Foundation.
2. Plant Physiology (June 2014): Two Mitogen-Activated Protein Kinases, MPK3 and MPK6, are required for Funicular Guidance of Pollen Tubes in Arabidopsis — Funded by a National Science Foundation grant and a NSF Young Investigator Award.
Jingyou Yu, a graduate student, does cell surface staining in Shan-Lu Liu’s virology lab. The staining illuminates cell marker expressions in experiments that deduce how viruses spread once they are contracted. | Paige Blankenbuehler
News headlines seem to feverishly spread as if they were a pandemic of the brain.
Ebola hemorrhagic fever has been the most talked about disease of the year, appearing in thousands of headlines across the world since May. Through the noise of misinformation and sensationalism, fundamental information about the pandemic becomes harder to distinguish.
In an interview with Decoding Science on Tuesday, Shan-Lu Liu, MD, PhD, a Bond Life Sciences Center investigator who studies Ebola, weighed in on the latest news.
Liu, also an associate professor in the MU School of Medicine’s Department of Molecular Microbiology and Immunology, and his lab are particularly interested in the early behaviors of the virus in transmission and how it can navigate around the host immune response.
Shan-Lu Liu, Bond Life Sciences scientists and associate professor in the MU School of Medicine department of molecular microbiology and immunology.
Q: Talk about the transmission. Ebola doesn’t spread through air, but how easily can it be transmitted through fluids?
A: It’s hard to say. It’s really not like: touch an infected person and you got it. I don’t see that could happen so easily. As an RNA virus, it’s not that stable outside of the body, unlike hepatitis B virus (HBV) where you need to boil the virus for 10 minutes and it becomes not infectious. Because Ebola is not that stable, that should not be the reason why it’s so efficient to transmit.
I think the transmission is one of the biggest things it’s, you know, I don’t think we have a complete understanding. We do know that it spreads by contact through body fluids and many people don’t realize that the handling of the deceased — that’s very dangerous. Touching broken skin or mucous membranes like the nose and mouth is dangerous.
Q: Talk about the incubation period and how that relates to symptoms and spreading of the virus.
A: The incubation time is 2-21 days. At first, the person will have flu-like symptoms, so you know, that’s why it’s hard to notice in the early stages. Some doctors or nurses say ‘just give him antibiotics send him home.’ But in stage two, you get the hemorrhage and it gets serious. The mortality rate is high, from 50 to 90 percent.
I think the fatality is definitely related to the late stages of the disease, especially with the hemorrhaging fever. The early stages are almost unnoticeable but that’s the time transmission might spread easier through contact with an infected person’s fluid. Before symptoms, the virus doesn’t spread.
Q: Last week, an article seemed to contradict with the CDC estimate. The headline: “Some good news about Ebola: It won’t spread nearly as fast as other epidemics.“ What do you make of that?
I don’t know, it’s hard for me to make a comment. Nobody knows. Things can always change. We didn’t expect to see a diagnosis in the United States — like this you know, this patient from Liberia was able to travel on a plane from virus country. Who can expect that? Anything can happen. There seem to have been some mishaps because he came from that area, right? Communication is more important now but it’s hard to predict because anything could happen.
Q: How has the Ebola virus behaved in previous outbreaks?
A: The first outbreak was in 1976 in Sudan and Congo — (Democratic Republic of Congo, known as Zaire at the time). It was from contaminated needles in a hospital and originally came from fruit bats — they are one of those animals that could transmit Ebola from animals to humans. The fruit bats transmitted the virus to primates, primates transmit to humans. It’s hard to notice in the early stages. Editor’s note: The 1976 outbreak was the first occurrence of Ebola in humans. The outbreak affected one village, infecting 318 people that resulted in 280 deaths.
Q: Much of the media has reported a vaccine for ebola was delayed. How could this happen?
A: Drugs and vaccines are a little different. The Ebola vaccine was delayed, that’s for sure. That’s because, the vaccine on trial has to go through tedious steps to get approval and so thats why when this outbreak occurs the NIH (National Institutes of Health) decides to go ahead quickly. One of the things for ebola vaccine is um, the pharmaceutical companies and the industries are not interested in developing vaccines. Do you know why? It is not a big market. Only a hundred — or a thousand or more — people will be infected by ebola, unlike other vaccines like the HPV vaccination where 200 million people need it. The companies are not interested in developing it, because there’s no money in it.
A company needs to spend a lot of money to develop a vaccine, but they don’t see the market — the market can’t do it. But somebody needs to do it. Imagine if, if the virus spread like this, you know, unpredictable, it could be worse. In terms of therapy, the drugs and antibodies, we know they are really effective. And they are specific, so they can reach the market effectively.
Q: Will a drug be enough to prevent wide spreading of Ebola?
I think the companies and governments are speeding up to make those available. To see this prediction (the CDC 1.4 million estimate), they have to be prepared. People have put increasing attention on antibodies because a vaccine is not in the near future. So what’s the approach? A “therapeutic vaccine.” The so-called therapeutic vaccine is an antibody so you engineer, you use you know, molecular engineering technique to generate those antibodies and they can neutralize and block viral infection. It’s more realistic for Ebola and even for HIV. The HIV vaccine has failed so many times. So that’s why I think one of the new approaches is to use a new broad neutralizing antibody.
Q: Does Ebola stay in the body, like chicken pox?
A: Ebola do not cause latent infection. HIV can become latent and become chronic. So influenza virus, ebola viral infection and others normally do not lead to latency. I think for Ebola — for this type of infection — once you block the patient and clear the virus it should be good.
Q: Has the media done a good job in educating the public?
I think in terms of news coverage they are pretty careful. I looked at the news conference by the CDC director and by those doctors in Dallas, and when they make statements they are careful not to exaggerate and also give very cautious measurements. The news media need to be aware of the danger of the virus. In the meantime, you have to be aware of the possibility of being affected.
Again, I think it is a very important problem. It’s important to let the public know the situation. If you see people who have recently traveled from those West African countries, you have to be cautious — air travel is so common. But I think the media have generally done a good job.
Q: Has the government done a good job keeping the pandemic under control?
I don’t know what they do. The air travel is a problem. Intensified screening process, that should definitely be done. It’s very bad for people from the outbreak area, and I just hope that this community won’t be affected.
To control, they should be careful. A person with any sign of the disease — they need to be quickly monitored and treated.
Q: What’s the most important take-away message for the public?
A: I think it’s an important problem and we need to solve it urgently. I hope this outbreak will teach us a lesson in terms of how important emerging infectious viruses are as it comes and goes is to public health. Based on literature and reports, if people do not have obvious symptoms, they do not produce an infectious virus. The incubation time has a big range but again, we are still trying to understand the process better. Infection is a complex process. We need to better understand the viral transmission so I think for now, we need to be very cautious.
Liu and his lab do not work with the contagious Ebola virus on University of Missouri campus. All of the studies involve use of a recombinant or pseudotyped Ebola virus which is not infectious.
