Aug. 13, 2012
Triclosan, an antibacterial chemical widely used in hand soaps and other personal-care products, hinders muscle contractions at a cellular level, slows swimming in fish and reduces muscular strength in mice, according to researchers at the University of California, Davis, and the university of Colorado. The findings appear online in the Proceedings of the National Academy of Sciences of the United States of America.
"Triclosan is found in virtually everyone's home and is pervasive in the environment," said Isaac Pessah, professor and chair of the Department of Molecular Biosciences in the UC Davis School of Veterinary Medicine and principal investigator of the study. "These findings provide strong evidence that the chemical is of concern to both human and environmental health."
Triclosan is commonly found in antibacterial personal-care products such as hand soaps as well as deodorants, mouthwashes, toothpaste, bedding, clothes, carpets, toys and trash bags. The U.S. Environmental Protection Agency in 1998 estimated that more than 1million pounds of triclosan are produced annually in the United States, and that the chemical is detectable in waterways and aquatic organisms ranging from algae to fish to dolphins, as well as in human urine, blood and breast milk.
The investigators performed several experiments to evaluate the effects of triclosan on muscle activity, using doses similar to those that people and animals may be exposed to during everyday life.
In "test tube" experiments, triclosan impaired the ability of isolated heart muscle cells and skeletal muscle fibers to contract. Specifically, the team evaluated the effects of triclosan on molecular channels in muscle cells that control the flow of calcium ions, creating muscle contractions. Normally, electrical stimulation ("excitation") of isolated muscle fibers under experimental conditions evokes a muscle contraction, a phenomenon known as "excitation-contraction coupling," the fundamental basis of any muscle movement, including heartbeats. But in the presence of triclosan, the normal communication between two proteins that
function as calcium channels was impaired, causing skeletal and cardiac muscle failure.
The team also found that triclosan impairs heart and skeletal muscle contractility in living animals. Anesthetized mice had up to a 25-percent reduction in heart function measures within 20 minutes of exposure to the chemical.
"The effects of triclosan on cardiac function were really dramatic," said Nipavan Chiamvimonvat, professor of cardiovascular medicine at UC Davis and a study co-author. "Although triclosan is not regulated as a drug, this compound acts like a potent cardiac depressant in our models."
In addition, the mice had an 18-percent reduction in grip strength for up to 60 minutes after being given a single dose of triclosan. Grip strength is a widely used measure of mouse limb strength, employed to investigate the effects of drugs and neuromuscular disorders.
Finally, the investigators looked at the effects of triclosan exposure on fathead minnows, a small fish commonly used as a model organism for studying the potential impacts of aquatic pollutants. Those exposed to triclosan in the water for seven days had significantly reduced swimming activity compared to controls during both normal swimming and swim tests designed to imitate fish being threatened by a predator.
"We were surprised by the large degree to which muscle activity was impaired in very different organisms and in both cardiac and skeletal muscle," said Bruce Hammock, a study co-author and professor in the UC Davis Department of Entomology. "You can imagine in animals that depend so totally on muscle activity that even a 10-percent reduction in ability can make a real difference in their survival."
The UC Davis research team has previously linked triclosan to other potentially harmful health effects, including disruption of reproductive hormone activity and of cell signaling in the brain.
Chiamvimonvat cautioned that translating results from animal models to humans is a large step and would require further study. However, the fact that the effects were so striking in several animal models under different experimental conditions provides strong evidence that triclosan could have effects on animal and human health at current levels of exposure.
"In patients with underlying heart failure, triclosan could have significant effects because it is so widely used," Chiamvimonvat said. "However, without additional studies, it would be difficult for a physician to distinguish between natural disease progression and an environmental factor such as triclosan."
Pessah questioned arguments that triclosan -- introduced more than 40 years ago -- is safe partly because it binds to blood proteins, making it not biologically available. Although triclosan may bind to proteins in the blood, that may not necessarily make the chemical inactive, he said, and actually may facilitate its transport to critical organs. In addition, some of the current experiments were carried out in the presence of blood proteins, and disrupted muscle activity still occurred.
Although triclosan was first developed to prevent bacterial infections in hospitals, its use has become widespread in antibacterial products used in the home. However, according to the U.S. Food and Drug Administration, other than its use in some toothpastes to prevent gingivitis, there is no evidence that triclosan provides other health benefits or that antibacterial soaps and body washes are more effective than regular soap and water. Experts also express concern about the possibility of resistant bacterial strains developing with the overuse of antibacterial products.
Because the chemical structure of triclosan resembles other toxic chemicals that persist in the environment, the FDA and the U.S. Environmental Protection Agency are conducting new risk assessments of the chemical. Based on their study outcomes, the researchers argue that the potential health risks call for greater restrictions.
"We have shown that triclosan potently impairs muscle functions by interfering with signaling between two proteins that are of fundamental importance to life," said Pessah. "Regulatory agencies should definitely be reconsidering whether it should be allowed in consumer products."
Said Hammock: "Triclosan can be useful in some instances, however it has become a ubiquitous 'value added' marketing factor that actually could be more harmful than helpful. At the very least, our findings call for a dramatic reduction in its use."
A copy of the study, titled "Triclosan impairs excitation-contraction coupling and Ca2+ dynamics in striated muscle," can be requested by e-mailing PNASNews@nas.edu.
Other authors of the study were Gennady Cherednichenko, Rui Zhang, Erika Fritsch, Wei Feng and Genaro Barrientos of the UC Davis School of Veterinary Medicine; Roger Bannister and Kurt Beam of the University of Colorado Denver-Anschutz Medical Campus; Valeriy Timofeyev and Ning Li of the UC Davis Division of Cardiovascular Medicine; and Nils Schebb of the UC Davis Department of Entomology. (Karen Finney, UC Davis Health News Service, (916) 734-9064 or karen.finney@ucdmc.ucdavis.edu)
Media contacts:
* Karen Finney, UC Davis Health News Service, (916) 734-9064 or karen.finney@ucdmc.ucdavis.edu
* Andy Fell, UC Davis News Service, (530) 752-4533, ahfell@ucdavis.edu
Chancellor Linda Katehi presented him the Distinguished Citation for Excellence Award.
Heydon was among two other individuals and two teams singled out for distinguished awards. Their names will be engraved on a perpetual plaque at the Walter A. Buehler Alumni and Visitors' Center.
Katehi praised them for their time, efforts and investments. “I’m so proud of you,” she told them. Rob Kerner, Staff Assembly president, read the accolades and described them as the “cream of the crop” of UC Davis employees.
“Steve is a true UC Davis goodwill ambassador in that he takes pride in the university, his department, his colleagues, and his work, which in itself, has drawn national and international acclaim,
Kerner said, in announcing the award. His colleagues described him as . "always willing to drop what he’s doing to help out a scientist, reporter, staff member, volunteer or the public. Steve treats everyone with the utmost respect and understanding, an earmark of an outstanding UC Davis employee." His nominators, colleagues Kathy Keatley Garvey, Tabatha Yang and Andrew Richards described him as "as a prized employee, the best of the best.”
The other recipients:
Individual Award, Supervision: Kathy Canevari, a former supervisor with UC Davis Extension who retired earlier this year.
Individual Award: Campus Service: Paul Cody, coordinator of the Campus Union Center for Student Involvement.
Team Award: General Contributions: School of Veterinary Medicine Dean’s Office, Curricular Support, comprised of Mike Beech, Melinda Carlson, Robin Houston, Linda Royce, Erin Seay, Linda Souza, Teresa Suter, and Ken Taylor.
Team Award: Campus Service: Office of Student Development management team comprised of associate director Catrina Wagner; and assistant directors Courtney Robinson, Richard Ronquillo, Chuck Huneke, and Lisa Papagni.
Others nominated for the distinguished awards and who were named finalists were:
Individual, General Contributions: David Irvine, Veterinary Medicine Teaching and Research Center; Israel G. Herrera, Agricultural Sustainability Institute, College of Agricultural and Environmental Sciences Dean’s Office; and Katy Bill, Services for International Students and Scholars
Individual Campus Service: Victor Duraj, Department of Biological and Agricultural Engineering
Team, General Contributions: Gourley Center-Academic Programs Staff comprised of Katie Almand. Jennifer Child, Meghan Culp, Tatiana Plitt, Morgan Brooks, Robert Favorite, Sarahjane Logan, Lorrie Spring, and Nicole White
Team Award, Campus Service: College of Engineering Shared Services, Human Resources/Payroll, comprised of Noreen Johnson, Stacey Veliz, Noemi Olvera, Debra Hamilton, and Justine Canevari. College of Engineering Shared Services, Purchasing and Accounts Payable: Pia Donaldson, Anna Finlay, Tiffany Hsieh, Denise Bray, Sondra Salazar, and Melanie Burt-Schipke.
Darla Tafoya of the Staff Assembly Executive Committee chaired the Citations for Excellence committee. Pamela Nardinelli serves as the Staff Assembly coordinator.
The Staff Assembly annually seeks nominees for the citations for excellence. UC Davis employees must have distinguished themselves in one or more of the three areas of outstanding achievement: general contributions, campus service or supervision. According to the Staff Assembly website: “We want to recognize staff who go above and beyond the expectations of their position descriptions, who contribute to the university’s mission of teaching, research, and service, and who exemplify outstanding achievement, supervisory skills, and/or service.” More information is at http://staff.ucdavis.edu/
ICE 2016 is expected to be the largest gathering of scientists and experts in the history of the entomological sciences, with an expected attendance of more than 6,000 delegates, Brown said. The Congress will be co-located with ESA's 64th annual meeting, along with other scientific society meetings. The latest global research on insect science will be presented under the theme, "Entomology without Borders.”
"ICE 2016 will provide a dynamic forum for the exchange of the latest science, research and innovations among entomologists all around the world,” Brown said. “Research shared will cover every aspect of the discipline and will bring thousands of experts together from every corner of the globe, many in person in Orlando and others remotely through the latest technologies. Students and early career scientists will have an once-in-a-lifetime opportunity to present their research in front of a global audience, to compete in global competitions, and will make important connections to last a lifetime."
"This event, supported by other international initiatives ESA has in the works, will help us significantly broaden the awareness of the science and society around the world, help us build more collaborative partnerships, and aid us in providing access for our members and others around the globe to the latest research and science," he said.
The ICE 2016 Organizing Committee will be co-chaired by Walter Leal, professor of entomology at UC Davis, and Alvin M. Simmons, a research entomologist with the U.S. Vegetable Laboratory of the USDA’s Agricultural Research Service, Charleston, S.C.
The ESA is the largest organization in the world, serving the professional and scientific needs of entomologists and people in related disciplines. Founded in 1889, ESA has more than 6,400 members affiliated with educational institutions, health agencies, private industry, and government.
For more information on ICE 2016, contact Rosina Romano, ESA director of meetings, at rromano@entsoc.org or call (301) 731-4535 x3010. --Richard Levine, ESA.
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
Chancellor Linda Katehi presented him the Distinguished Citation for Excellence Award.
Heydon was among two other individuals and two teams singled out for distinguished awards. Their names will be engraved on a perpetual plaque at the Walter A. Buehler Alumni and Visitors' Center. The awards are sponsored by the UC Davis Staff Assembly.
Katehi praised them for their time, efforts and investments. “I’m so proud of you,” she told them. Rob Kerner, Staff Assembly president, read the accolades and described them as the “cream of the crop” of UC Davis employees.
“Steve is a true UC Davis goodwill ambassador in that he takes pride in the university, his department, his colleagues, and his work, which in itself, has drawn national and international acclaim, Kerner said, in announcing the award. His colleagues described him as . "always willing to drop what he’s doing to help out a scientist, reporter, staff member, volunteer or the public. Steve treats everyone with the utmost respect and understanding, an earmark of an outstanding UC Davis employee."
His nominators, colleagues Kathy Keatley Garvey, Tabatha Yang and Andrew Richards described him as "as a prized employee, the best of the best.”
The other recipients:
Individual Award, Supervision: Kathy Canevari, a former supervisor with UC Davis Extension who retired earlier this year.
Individual Award: Campus Service: Paul Cody, coordinator of the Campus Union Center for Student Involvement.
Team Award: General Contributions: School of Veterinary Medicine Dean’s Office, Curricular Support, comprised of Mike Beech, Melinda Carlson, Robin Houston, Linda Royce, Erin Seay, Linda Souza, Teresa Suter, and Ken Taylor.
Team Award: Campus Service: Office of Student Development management team comprised of associate director Catrina Wagner; and assistant directors Courtney Robinson, Richard Ronquillo, Chuck Huneke, and Lisa Papagni.
Others nominated for the distinguished awards and who were named finalists were:
Individual, General Contributions: David Irvine, Veterinary Medicine Teaching and Research Center; Israel G. Herrera, Agricultural Sustainability Institute, College of Agricultural and Environmental Sciences Dean’s Office; and Katy Bill, Services for International Students and Scholars
Individual Campus Service: Victor Duraj, Department of Biological and Agricultural Engineering
Team, General Contributions: Gourley Center-Academic Programs Staff comprised of Katie Almand. Jennifer Child, Meghan Culp, Tatiana Plitt, Morgan Brooks, Robert Favorite, Sarahjane Logan, Lorrie Spring, and Nicole White
Team Award, Campus Service: College of Engineering Shared Services, Human Resources/Payroll, comprised of Noreen Johnson, Stacey Veliz, Noemi Olvera, Debra Hamilton, and Justine Canevari. College of Engineering Shared Services, Purchasing and Accounts Payable: Pia Donaldson, Anna Finlay, Tiffany Hsieh, Denise Bray, Sondra Salazar, and Melanie Burt-Schipke.
Darla Tafoya of the Staff Assembly Executive Committee chaired the Citations for Excellence committee. Pamela Nardinelli serves as the Staff Assembly coordinator.
The Staff Assembly annually seeks nominees for the citations for excellence. UC Davis employees must have distinguished themselves in one or more of the three areas of outstanding achievement: general contributions, campus service or supervision. According to the Staff Assembly website: “We want to recognize staff who go above and beyond the expectations of their position descriptions, who contribute to the university’s mission of teaching, research, and service, and who exemplify outstanding achievement, supervisory skills, and/or service.” More information is at http://staff.ucdavis.edu/
Aug. 7, 2012
DAVIS--A certain species of yeast that UC Davis researchers found in “almost all” their samples of raspberries and cherries infested by the spotted-wing drosophila (Drosophila suzukii), may lead to a better lure to detect the invasive pest in the field.
A research team from the UC Davis Department of Entomology, the Department of Food Science and Technology, and a visiting professor from the University of Extremadura, Spain, found that the yeast, Hanseniaspora uvarum, appeared in just about every cherry, raspberry, and larva of the spotted-wing drosophila (SWD) that they sampled at collection points in Davis, Winters, and Watsonville.
The agricultural pest, native to southeast Asia and now found in many parts of North America, was first observed in California in the fall of 2008 in the central valley, but was not identified until early 2009. It is reported to attack soft-skinned, ripening fruits, and has been a particular problem for raspberry and cherry growers in California.
The research team--comprised of Phaff Yeast Collection curator Kyria Boundy-Mills of the UC Davis Department of Food Science and Technology; entomology professor and integrated pest management specialist Frank Zalom; graduate PhD student Kelly Hamby in the Zalom lab; and UC Davis visiting professor Alejandro Hernandez of University of Extremadura, Spain--published their work in a recent cover article of the journal Applied and Environmental Microbiology, the No. 1 cited journal in microbiology.
"This represents the first look at potential yeast associations of Drosophila suzukii," said Hamby.
“We are now testing to see if this species will be a good lure to detect this fly in the field,” Boundy-Mills said.
“When we started the work we hoped to find candidate yeast species that could be used to improve the bait in Drosophila suzukii traps,” Hamby said. “Fruit flies are regularly trapped with apple cider vinegar or baker's yeast and sugar plus water so these were the traps that were originally recommended for monitoring when SWD first invaded California in 2008.”
“Unfortunately, these lures trap all fruit flies, and many other non-target insects, so the hope was that we might be able to design a more selective and attractive lure by identifying a more specific yeast that is used by SWD,” Hamby said.
“Often Drosophila have interactions with yeast communities, and communities often vary between host plant species, so it was a bit of a surprising that we found Hanseniaspora uvarum so often, though, we used only culture-based methods so other yeasts may be present that are hard to culture,” Hamby said.
Zalom and Burrack had earlier collaborated with Boundy-Mills, “so our lab already had an established collaboration with a yeast systematist before we dreamed up this project,” Hamby noted. “Kyria curates a huge UC Davis yeast collection and all the yeast strains we found were deposited into the Phaff collection.”
Boundy-Mills pointed out that SWD is causing major crop damage to soft fruits such as berries and that better detection and control methods are needed.
In their journal article, the authors wrote that “D. suzukii is unique in that it oviposits on marketable fruit relative to overripe or damaged fruit, and its injury facilitates colonization by other Drosophila species. If untreated, it is capable of causing a potential $860 million of revenue loss annually to blackberries, raspberries, and cherries in California, Oregon, and Washington. Knowledge of potential yeast associations could be used in lure development.”
Zalom said the pest is a major problem in the area for backyard cherries. “Many residents have not being able to harvest cherries for several years now.”
For the cover photo, Hamby created a Drosophila suzukii drawn with yeasts on potato dextrose agar. “Eyes and wing spots were drawn with Rhodotorula mucilaginosa, while Rhodosporidium toruloides and the Drosophila suzukii-associated yeast Hanseniaspora uvarum were used for the outline and the interior, respectively,” according to the photo caption in the journal. The photo was taken by Kathy Keatley Garvey, UC Davis Department of Entomology.
The Phaff Yeast Culture Collection is one of the world’s largest collections of wild yeasts. Boundy-Mills’ work as curator involves maintaining the collection, distributing strains to academic and industrial researchers around the world, conducting contract screening research for companies, and research on yeast ecology. Her current research projects include yeast farming by Drosophila fruit flies; isolation of yeasts, bacteria and molds from wood-feeding beetle larvae in Indonesia; screening yeasts for high lipid production for biofuels applications; and screening yeasts for novel therapeutics
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
