There are important lessons to be learned in the United States from the recent eruption of foodborne illness in Germany — which has turned out to be the deadliest E. coli outbreak ever — according to a food-safety expert in Penn State’s College of Agricultural Sciences.
More than 3,300 people have been sickened since the outbreak began, including nearly 800 with a serious complication that can lead to kidney failure and death. German health officials finally were able to trace the illness back to bean sprouts grown on a farm in northern Germany, but not before at least 39 people died.
Not all strains of E.coli are harmful. However, the strain that has caused the German outbreak is very pathogenic. (Credit: Penn State)
It’s a sobering example of how vital it is for health officials to be able to trace food back to its origin on the farm when an outbreak of foodborne illness occurs, said Luke LaBorde, associate professor of food science. LaBorde conducts extension programs that train farmers to use “good agricultural practices” (GAPs) aimed at preventing contamination in products such as sprouts, lettuce, tomatoes and cucumbers.
“The German officials simply were not able to trace the outbreak back quickly enough to determine where it started and what food was involved,” he said. “That’s why so many people got sick.”
“The seeds that producers buy for growing sprouts can be contaminated without any indication that they are unsafe to use,” he said. “So they are just going to continue using that seed until someone tells them, ‘Hey, that is making people sick.'”
LaBorde said the new federal food-safety law recently adopted in this country contains provisions that will enable scientists and government food-safety agencies to quickly trace foods back to their origins on the farm.
Now, every package or container of produce must include information about where a food product was grown or created. And because contamination can happen in processing, transport and storage, information about those also are logged and preserved, LaBorde pointed out.
In retrospect, he’s not surprised that sprouts were determined to be the cause of the German E. coli outbreak. “We’ve known for a long time that sprouts can be a problem,” he said. “The seeds may become contaminated by bacteria in animal manure in the field or during post-harvest storage.”
The process used to germinate seeds is ideal for growing pathogens, LaBorde added. “Abundant nutrients are present, along with high levels of moisture — and the warm temperatures needed for the sprouting process help to ensure survival and growth of bacteria,” he said.
“Mishandling of sprouts during production, packing or distribution has rarely been implicated as the source of sprout contamination. However, bacteria already present in the sprouting seed can continue to thrive if proper food-handling techniques are not practiced during harvest, processing and preparation.”
In the United States, the seeds usually are pre-treated with concentrated bleach solutions, and wash water that flows through the sprouts is collected and tested for bacteria such as E. coli, LaBorde explained.
“Perhaps that has not been done in Germany,” he said. “Increasingly in this country, we are testing irrigation water and wash water for contamination. There typically is a lot more surveillance here.”
LaBorde noted that increasing government testing and regulation is controversial in some circles because it adds costs and makes food more expensive, but politics and food safety aren’t compatible when people start getting sick due to foodborne illness.
“There was all sorts of hysteria before the new federal food-safety law came out about how small farmers would be unable to come up with new systems to handle the testing and reporting it required — record keeping was a real concern,” he said.
“And so there were some exceptions put into the bill that exempted growers with less than $500,000 in sales who sell direct to consumers or food stores.”
But regulation is a moot point in the marketplace, LaBorde contended, because food safety has been pushed onto the buyers. Each buyer — such as a huge supermarket chain — has their own standards that they impose on producers, and they are getting tougher and tougher. Small farmers and huge operations alike must abide by them.
“The private companies are way ahead of the government, and many now are requiring a third-party inspection of produce,” he said. “There are no politics in the private food industry — it is the bottom line that drives things.
“The large grocery store companies have simply decided they don’t want to deal with multimillion-dollar lawsuits against them involving contaminated foods. So they are requiring suppliers to put into place processes, tests and requirements — such as produce being GAPs certified — that guard against pathogens being present in their products.”
But LaBorde advises people to be aware that sprouts are just inherently more risky. “Even the Food and Drug Administration has said you can soak sprouts in bleach and still not kill every pathogen,” he said.
“You can’t reverse contamination, and the way sprouts are grown, if there is even the smallest amount of contamination present, it can multiply greatly and make people sick.”
A new study in fruit flies offers a broad view of the potent and sometimes devastating molecular events that occur throughout the body as a result of methamphetamine exposure.
The study, described in the journal PLoS ONE, tracks changes in the expression of genes and proteins in fruit flies (Drosophila melanogaster) exposed to meth.
Unlike most studies of meth, which focus on the brain, the new analysis looked at molecular changes throughout the body, said University of Illinois entomology professor Barry Pittendrigh, who led the research.
“One of the great things about working with fruit flies is that because they’re small, we can work with the whole organism and then look at the great diversity of tissues that are being impacted,” Pittendrigh said. “This is important because we know that methamphetamine influences cellular processes associated with aging, it affects spermatogenesis, and it impacts the heart. One could almost call meth a perfect storm toxin because it does so much damage to so many different tissues in the body.”
By tracking changes in gene expression and protein production of fruit flies exposed to meth, the researchers identified several molecular pathways significantly altered by the drug.
Many of these cascades of chemical reactions within cells are common to many organisms, including humans, and are similar even among very different families of organisms.
The researchers found that meth exposure influenced molecular pathways associated with energy generation, sugar metabolism, sperm cell formation, cell structure, hormones, skeletal muscle and cardiac muscles. The analysis also identified several new molecular players and unusual disruptions of normal cellular events that occur in response to meth, though the authors acknowledge that further work is required to validate the role of these pathways in response to meth.
Illinois crop sciences professor Manfredo Seufferheld, a co-author on the study, saw changes that indicate that meth exposure may alter the cell’s energy metabolism in a manner that mirrors changes that occur in rapidly growing cancer cells. Most types of cancer rely primarily on the rapid breakdown of glucose in a process called glycolysis, which does not require oxygen even when oxygen is available. In contrast, healthy cells tend to use oxidative respiration, a slower and more efficient energy-generating process that occurs in the presence of oxygen. This aberration in energy metabolism observed in cancer cells is called the Warburg effect.
“The discovery of the molecular underpinnings of the meth syndrome in Drosophila – based on a systems biology approach validated by mutant analysis – has the potential to be used in advancing our knowledge about malignant cell proliferation by understanding the connections behind the Warburg effect and cell death,” Seufferheld said.
Since glycolysis uses glucose to produce energy, the researchers tested the hypothesis that sugar metabolism is involved in the “toxic syndrome” spurred by meth. They found that meth-exposed fruit flies lived longer if they consumed trehalose, a major blood sugar in insects that also is an antioxidant.
Human meth users are known to crave sugary drinks, said lead author Lijie Sun. “And now we have evidence that increased sugar intake has a direct impact on reducing the toxicity of meth, at least in flies.”
The researchers found that meth caused changes that may interfere with the critical balance of calcium and iron in cells, and they were the first to identify numerous genes that appear to be involved in the meth-induced dysfunction of sperm formation.
“All in all, this study shows that Drosophila melanogaster is an excellent model organism in which to study the toxic effect of methamphetamine at the molecular level,” said Illinois postdoctoral researcher Kent Walters, an author on the study.
The study team also included researchers from the University of Nebraska (Jiri Adamec); Purdue University (William Muir, Eric Barker, Jun Xie, Venu Margam, Amber Jannasch, Naomi Diaz and Catherine Riley); Chung Hwa College of Medical Technology, Taiwan (Yueh-Feng Li); Carnegie Mellon University (Jing Wu); Indiana University (Jake Chen and Fan Zhang); and others at the
U. of I. (Hongmei Li and Weilin Sun). Lijie Sun, who earned her doctorate in Pittendrigh’s laboratory when he was a professor at Purdue, now is working at the J. Craig Venter Institute under Hamilton O. Smith, who won the 1978 Nobel Prize in the physiology or medicine category.
Source: University of Illinois at Urbana-Champaign
Atmospheric sciences professor Stephen Nesbitt, left, and graduate student Daniel Harnos analyzed passive microwave satellite data to identify telltale structural rings in tropical storms that are about to intensify into hurricanes.(Credit: Photo by L. Brian Stauffer)
Coastal residents and oil-rig workers may soon have longer warning when a storm headed in their direction is becoming a hurricane, thanks to a University of Illinois study demonstrating how to use existing satellites to monitor tropical storm dynamics and predict sudden surges in strength.
“It’s a really critical piece of information that’s really going to help society in coastal areas, not only in the U.S., but also globally,” said atmospheric sciences professor Stephen Nesbitt. Nesbitt and graduate student Daniel Harnos published their findings in the journal Geophysical Research Letters.
Meteorologists have seen large advances in forecasting technology to track the potential path of tropical storms and hurricanes, but they’ve had little success in predicting storm intensity. One of the biggest forecast problems facing the tropical meteorology community is determining rapid intensification, when storms suddenly transform into much stronger cyclones or hurricanes.
“Rapid intensification means a moderate-strength tropical storm, something that may affect a region but not have a severe impact, blowing up in less than 24 hours to a category 2 or 3 hurricane,” Harnos said. “This big, strong storm appears that wasn’t anticipated, and the effects are going to be very negative. If you don’t have the evacuations in place, people can’t prepare for something of the magnitude that’s going to come ashore.” For example, Hurricane Charlie, which hit southern Florida in 2004, was initially forecast as a category 1 storm. However, when it made landfall less than 24 hours later, it had strengthened to a category 4, causing major damage.
Rapid intensification is so hard to predict in part because it’s driven by internal processes within the storm system, rather than the better-predicted, large-scale winds that determine the direction of the storms. The satellite imagery most commonly used for meteorology only looks at the clouds at the top of the storms, giving little insight as to what’s going on inside the system.
Harnos and Nesbitt focused their study on passive microwave satellite imagery. Such satellites are used commonly for estimating precipitation, but the Illinois researchers focused on using these sensors to systematically observe hurricane structure and intensity changes. Their study was the first to use objective techniques to investigate a convective ring structure that has been observed in tropical cyclones.
“What makes it ideal for what we are doing is that it’s transparent to clouds. It senses the amount of ice within the clouds, which tells us the strength of convection or the overturn of the atmosphere within the hurricane,” Nesbitt said. “It’s somewhat like trying to diagnose somebody with a broken arm by taking a picture of the arm, versus being able to X-ray it.”
The researchers scoured data from passive microwave satellites from 1987 to 2008 to see how hurricanes behaved in the 24 hours before a storm underwent rapid intensification. Such a big-picture approach, in contrast to the case studies atmospheric scientists often perform, revealed clear patterns in storm dynamics. They found that, consistently, low-shear storm systems formed a symmetrical ring of thunderstorms around the center of the system about six hours before intensification began. As the system strengthened into a hurricane, the thunderstorms deepened and the ring became even more well-defined.
The study also looked at high-shear storms, a less common phenomenon involving atmospheric winds hanging with height. Such storms showed a different structure when intensifying: They form a large, bull’s-eye thunderstorm in the center of the system, rather than a ring around the center.
“Now we have an observational tool that uses existing data that can set off a red flag for forecasters, so that when they see this convective ring feature, there’s a high probability that a storm may undergo rapid intensification,” Nesbitt said. “This is really the first way that we can do this in real time rather than guessing with models or statistical predictions.”
Since passive microwave satellites orbit every three to six hours, meteorologists can use them to track tropical storms and watch for the telltale rings to give forecasters about a 30-hour window before a storm hits its maximum strength.
Next, the researchers hope to even further increase their forecasting ability by modeling the internal dynamics of the storm systems as they intensify to pinpoint the causes of the structural changes they observed and find out what drives the intensification process.
“The satellite gives up as snapshot of what’s taking place,” Harnos said. “We know what’s going on, but not how those changes are occurring to end up in the pattern that we’re seeing. So what we’re working on now is some computer modeling of hurricanes, both real storms and idealized storms, to see dynamically, structurally, what’s taking place and what changes are occurring to produce these patterns that we see in the satellite data.”
The NASA Hurricane Science Research Program supported this work.
Source: University of Illinois at Urbana-Champaign
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Wing size differences between two Nasonia wasp species are the result of newly discovered genetic differences between the species. The diversity of size and shape differences between other animal species may have similar origins. Credit: David Loehlin, University of Wisconsin, Madison
From spaghetti-like sea anemones to blobby jellyfish to filigreed oak trees, each species in nature is characterized by a unique size and shape. But the evolutionary changes that produce the seemingly limitless diversity of shapes and sizes of organisms on Earth largely remains a mystery. Nevertheless, a better understanding of how cells grow and enable organisms to assume their characteristic sizes and shapes could shed light on diseases that involve cell growth, including cancer and diabetes.
Providing new information about the evolution of the diversity of sizes and shapes in nature is a study identifying genetic differences between two closely related species of Nasonia wasps. These differences give males of one of the Nasonia species small flightless wings and the males of the other Nasonia species flight-worthy wings that are twice as large.
Jack Werren and David Loehlin at the University of Rochester led the research. (Loehlin is now a post-doc at the University of Wisconsin-Madison). Funded by the National Science Foundation (NSF), this week’s issue of Science covers the research.
The research team identified the chromosomal location of the gene responsible for wing size in each of the two Nasonia species, the differences between the DNA sequences of these genes, as well as regulatory controls that determine when, where and how long each species’ growth gene is turned on.
These genetic differences alter both the locations of growth centers in the wings and the timing of growth during Nasonia development–factors that give each species its distinct wing size. As evidence that the identified genes control wing size, the researchers nearly doubled the wing size of the small-winged species by cross-breeding into it the gene from the big-winged species.
Interestingly, Loehlin says the team’s results indicate multiple genetic changes caused the differences in Nasonia wing size-changes, and these changes may have occurred incrementally. “It is possible that the diversity of size and shape differences between other animal species have similar origins in regulator DNA. And the gene we identified is thought to control growth in many other animals, including people.”
The researchers suspect that the small winged Nasonia species evolved from the big-winged species, but it is also possible that the two species evolved in the opposite order.
“Understanding the types of changes in DNA that are responsible for evolution is critical to unraveling the causes of life’s diversity,” says Samuel Scheiner, a program director at NSF. “The recent explosion of new tools for DNA sequencing is now allowing this understanding. This study demonstrates that changes in gene regulation can be important for such evolution.”
The two studied species of Nasonia wasps were chosen for this research because their close genetic relationship coupled with the large difference in their wing sizes makes genetic comparisons between them particularly easy. Nasonia wasps have become a model system for studying evolution because their genetics and breeding system simplify the identification of genetic changes behind complex traits.
Not all strains of E.coli are harmful. However, the strain that has caused the German outbreak is very pathogenic. (Credit: Penn State)
Atmospheric sciences professor Stephen Nesbitt, left, and graduate student Daniel Harnos analyzed passive microwave satellite data to identify telltale structural rings in tropical storms that are about to intensify into hurricanes.(Credit: Photo by L. Brian Stauffer)
