 |
|
Genetic differences in clover make one type toxic
October 02, 2007Botanical 'cloak and dagger'
That clover necklace you make for your child could well be a ring of poison. That's because some clovers have evolved genes that help the plant produce cyanide - to protect itself against little herbivores, such as snails, slugs and voles, that eat clover. Other clover plants that do not make cyanide are found in climates with colder temperatures. So, in picking your poison, er, clover, ecology and geography play important roles.
A plant evolutionary biologist at Washington University in St. Louis is trying to get to the bottom of this botanical cloak and dagger tale. Kenneth Olsen, Ph.D., Washington University assistant professor of biology in Arts & Sciences, is looking at the genetics of a wide variety of white clover plants to determine why some plants do and some plants don't make cyanide - what biologists call polymorphism, or two types.
"We are documenting the effect of natural selection at the DNA sequence level to understand the molecular evolution of this polymorphism," said Olsen. "Usually, researchers study model plants such as Arabidopsis or tobacco to understand genetics. But with clover we have a system where we can look in detail at DNA sequence variation and at the same time have a thorough understanding of the plant's ecology."
In a study published the week of Sept. 24 in the journal Molecular Ecology, Olsen and his colleagues report findings on the molecular basis of the cyanide polymorphism.
Cyanide "bomb" in cell
White clover is native to Europe and Asia and was introduced some 300 years ago in North America. The cold factor-acyanogenic relationship has been known a long time in Europe and Asia and it re-evolved in North America when the plant was introduced, indicating that natural selection was a powerful force in shaping the geographical distributions of the two plant types.
The genetic basis behind cyanide production in clover plants boils down to just two genes.
"A cyanogenic plant sets up a little cyanide bomb in the cell," Olsen explained. "You have a cyanogenic glucoside - basically a sugar with a cyanide group stuck onto it, in the cell vacuole, and then in the cell wall there is an enzyme required to hydrolyze the cyanide. If something damages the cell, these two compounds come into contact with each other and free cyanide is released." One gene, Li, encodes the enzyme, which is called linamarase; another gene, Ac, is responsible for the presence or absence of cyanogenic glucosides.
Olsen's recent findings have revealed that plants that do not synthesize linamarase are lacking the Li gene altogether: the gene's DNA is absent from genomes of these plants.
Olsen and colleagues are also testing hypotheses on why acyanogenic plants occur in cold climates. One poses that there are fewer herbivores in colder climates.
"If a plant can get by without investing in all the resources it takes to be cyanogenic, it can concentrate those resources in other forms of growth and reproduction, then it would be out competing the plants that are cyanogenic," Olsen said.
Suicide not ruled out
The second hypothesis explores the lurid possibility of plant suicide. "In hypothesis two, we question the role of frequent frosts. The frosts could cause cell rupture and the release of cyanide leading to autotoxicity. If cyanogenic plants are poisoning themselves in cold climates, then those plants will be at a disadvantage."
To examine both the weather factor and suicide possibility, Olsen and his colleagues are testing different types of clovers in freeze chambers at controlled temperatures to see if survival is higher for either acyanogenic or cyanogenic plants.
"The advantage of the clover cyanogenesis system is there's already so much known about its ecology," Olsen said. "What we're able to do now is get to the molecular level and look at the molecular basis of ecologically important variation."
Washington University in St. Louis
"We are documenting the effect of natural selection at the DNA sequence level to understand the molecular evolution of this polymorphism," said Olsen. "Usually, researchers study model plants such as Arabidopsis or tobacco to understand genetics. But with clover we have a system where we can look in detail at DNA sequence variation and at the same time have a thorough understanding of the plant's ecology."
In a study published the week of Sept. 24 in the journal Molecular Ecology, Olsen and his colleagues report findings on the molecular basis of the cyanide polymorphism.
Cyanide "bomb" in cell
White clover is native to Europe and Asia and was introduced some 300 years ago in North America. The cold factor-acyanogenic relationship has been known a long time in Europe and Asia and it re-evolved in North America when the plant was introduced, indicating that natural selection was a powerful force in shaping the geographical distributions of the two plant types.
The genetic basis behind cyanide production in clover plants boils down to just two genes.
"A cyanogenic plant sets up a little cyanide bomb in the cell," Olsen explained. "You have a cyanogenic glucoside - basically a sugar with a cyanide group stuck onto it, in the cell vacuole, and then in the cell wall there is an enzyme required to hydrolyze the cyanide. If something damages the cell, these two compounds come into contact with each other and free cyanide is released." One gene, Li, encodes the enzyme, which is called linamarase; another gene, Ac, is responsible for the presence or absence of cyanogenic glucosides.
Olsen's recent findings have revealed that plants that do not synthesize linamarase are lacking the Li gene altogether: the gene's DNA is absent from genomes of these plants.
Olsen and colleagues are also testing hypotheses on why acyanogenic plants occur in cold climates. One poses that there are fewer herbivores in colder climates.
"If a plant can get by without investing in all the resources it takes to be cyanogenic, it can concentrate those resources in other forms of growth and reproduction, then it would be out competing the plants that are cyanogenic," Olsen said.
Suicide not ruled out
The second hypothesis explores the lurid possibility of plant suicide. "In hypothesis two, we question the role of frequent frosts. The frosts could cause cell rupture and the release of cyanide leading to autotoxicity. If cyanogenic plants are poisoning themselves in cold climates, then those plants will be at a disadvantage."
To examine both the weather factor and suicide possibility, Olsen and his colleagues are testing different types of clovers in freeze chambers at controlled temperatures to see if survival is higher for either acyanogenic or cyanogenic plants.
"The advantage of the clover cyanogenesis system is there's already so much known about its ecology," Olsen said. "What we're able to do now is get to the molecular level and look at the molecular basis of ecologically important variation."
Washington University in St. Louis
Cyanide Current Events and Cyanide News RSSUsing live fish, new tool a sentinel for environmental contamination
Researchers have harnessed the sensitivity of days-old fish embryos to create a tool capable of detecting a range of harmful chemicals.
Arecibo telescope finds critical ingredients for the soup of life in a galaxy far, far away
Astronomers from Arecibo Observatory radio telescope in Arecibo, Puerto Rico, have detected for the first time the molecules methanimine and hydrogen cyanide - two ingredients that build life-forming amino acids - in a galaxy some 250 million light years away.
U of M researchers discover fast-acting cyanide antidote
University of Minnesota Center for Drug Design and Minneapolis VA Medical Center researchers have discovered a new fast-acting antidote to cyanide poisoning. The antidote has potential to save lives of those who are exposed to the chemical - namely firefighters, industrial workers, and victims of terrorist attacks.
How did chemical constituents essential to life arise on primitive Earth?
Experiments show that simple molecules can combine chemically rather than biologically to form the building blocks of DNA, the key component of all life forms. These processes might have taken place on primitive earth, but how they occur is an unsolved puzzle.
Hearts of male and female rainbow trout are different
The heart is one of the most energy demanding organs of the human body. Its failure to function properly accounts for 600,000 deaths each year. Similarly, the rainbow trout, native to the Pacific Northwest and beloved as a sport- and food fish, requires dynamic and sustained cardiac function to maintain its health and swimming activity.
Massive coral death atrributed to earthquake
Scientists have reported what is thought to be one of the world's greatest mass death of corals ever recorded as a result of the earthquake in Aceh, Indonesia on 28 March 2005.
Massive coral death attributed to earthquake
Scientists have reported what is thought to be one of the world's greatest mass death of corals ever recorded as a result of the earthquake in Aceh, Indonesia on 28 March 2005.
Scripps research scientists: Compounds show significant promise against potential bioweapon toxins
Because of the high cost and limited applicability of currently available treatments, the newly identified compounds have the potential to fill the existing therapy gap and to provide protection against a bioterrorism attack using the toxin.
Nano design adjustment may help find, clear some water contaminants
Experiments designed to test discrepancies in theoretical computational chemistry have turned up a barely two-angstrom difference that may lead to a new approach to locate and remove dangerous toxins such as perchlorate and nitrates from the environment.
Earth's Most Diverse Marine Life Found Off Indonesia's Papua Province
Two recent expeditions led by Conservation International (CI) to the heart of Asia's "Coral Triangle" discovered dozens of new species of marine life including epaulette sharks, "flasher" wrasse and reef-building coral, confirming the region as the Earth's richest seascape.
More Cyanide Current Events and Cyanide News Articles
 | The Cyanide Canary by Joseph Hilldorfer, Robert Dugoni "The Cyanide Canary" is the riveting true story of a horrific crime -- of a brave young man left for dead, an unscrupulous business mogul, and the relentless EPA investigator who fought to overcome injustice. On a crisp summer morning in Soda Springs, Idaho, twenty-year-old Scott Dominguez kissed his fiance e goodbye and went to work for Allan Elias, the owner of Evergreen Resources, an... |
 | Between Silk and Cyanide: A Codemaker's War, 1941-1945 by Leo Marks In 1942, Leo Marks left his father's famous bookshop, 84 Charing Cross Road, and went off to fight the war. He was twenty-two. Soon recognized as a cryptographer of genius, he became head of communications at the Special Operations Executive (SOE), where he revolutionized the codemaking techniques of the Allies and trained some of the most famous agents dropped into occupied Europe, including... |
 | The Little Cyanide Cookbook; Delicious Recipes Rich in Vitamin B17 by June de Spain A professional nutritionist offers over 300 tasty recipes rich in the cyanide containing substance that many scientists believe is nature’s control for cancer. Cyanide, in minute quantities and in proper food forms, instead of being poisonous, actually is essential to health. 192-page... |
 | Sparkling Cyanide (St. Martin's Minotaur Mysteries) by Agatha Christie It's been less than a year since beautiful heiress Rosemary Barton took her own life during a birthday dinner in her honor. Her husband George never believed that his fun-loving wife would commit suicide--especially now that he's received two anonymous letters that suggest cold-blooded murder. One implicates even George himself. It's true he long suffered Rosemary's infidelities. But what about... |
 | Cyanide in Water and Soil: Chemistry, Risk, and Management The presence of cyanide is a significant issue in industrial and municipal wastewater treatment and management, in remediation of former manufactured gas plant sites and aluminum production waste disposal sites, in treatment and management of residuals from hydrometallurgical gold mining, and in other industrial operations in which cyanide-bearing wastes were produced. The complexity of the... |
| Cyanide & Happiness: No Suicides Allowed by Kris Wilson | |
 | Bitter Almonds : The True Story of Mothers, Daughters, and the Seattle Cyanide Murders by Gregg Olsen Stella Nickell's small-time world was one of big-time dreams. In 1986, her biggest one came true when her husband died during a seizure, making her the beneficiary of a $175,000-plus insurance payoff--until authorities discovered Bruce Nickell's headache capsules had been laced with cyanide. In an attempt to cover her tracks, Stella did the unconscionable. She saw to it that a stranger would also... |
 | Operation Cyanide: How the Bombing of the USS Liberty Nearly Caused World War III by Peter Hounam The USS Liberty was attacked by unmarked planes and torpedo boats in international waters during the Six Day War between Israel and the Arab States. The attack on the surveillance ship lasted 75 minutes -- 34 men died and 172 were injured. Initially it was thought that either Egypt or the U.S.S.R. was responsible, but astonishingly Israel, the U.S.'s closest ally, said that the planes and boats... |
 | Cyanide Wells by Marcia Muller Matt Lindstrom was falsely accused of his wife Gwen's murder. Fourteen years later he discovers that she is living a new life. Shocked to discovers that she has a child and is living with a lesbian lover, Matt journeys to find that tragedy has struck again. He must prevent a final confrontation that may prove fatal to them... |
 | Cyanide and Sin: Visualizing Crime in 50s America by Will Straw 3000 copies, the entire edition. Designed by Alexander Gelman and Andrew Roth. Cyanide and Sin offers a broad history of the true crime magazine in America with an emphasis on its visual content, during the 1950s. With 196 color illustrations, Will Straw, a scholar teaching in the Communications Department at McGill University in Montreal, Canada, has written a 12,000 word essay that traces... |
| © 2008 BrightSurf.com |