Tuesday, December 28, 2010


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While trying to figure out what makes certain beverages cloudy, Cornell researchers made the startling discovery that certain chemicals in green tea -- and perhaps red wine -- react with saliva in ways that can alter how we perceive flavors.

Specifically, regular consumption of the polyphenol-rich drinks can boost astringent sensations and our sensitivity to acids, reports Karl Siebert, professor of food science, in an article published online in Food Quality and Preference Sept. 21 and in print January 2011.

Siebert also discovered that we all have varying levels of polyphenols already stored in our systems.

Siebert, who worked for 18 years in a brewery before becoming an academic, stumbled upon the finding while studying the relationship between polyphenols -- chemical compounds found in plants -- and protein chains in such drinks as beer and apple juice.

It was well known that the two combine to form complexes. The larger these complexes grow, the less soluble they become, until they become visible to the human eye in the form of haze or turbidity.

Siebert's group discovered the strong effect of pH on haze formation, peaking at a pH level near 4. More acidic beverages like grape juice don't get as cloudy. Higher pHs also lead to less haze.

These findings led Siebert to question whether the same thing happened in people's mouths.

We perceive astringency, which is a tactile (touch) sensation, similarly to how we perceive the cooling of menthol and the heating (or pain) of capsaicin, the hot pepper compound. The traditional thinking was that the astringency was caused by a loss of lubrication when polyphenols reacted with proteins in saliva.

Siebert wondered if pH levels made a difference there too, and if so, why.

"We had this idea because of what we had seen before about the protein effect in beverages, and we knew that acid together with polyphenols tastes more astringent than either alone," Siebert said.

He presented several dilute solutions of acid to a group of panelists, who rated the intensity of astringency. While most reported a mild difference, others had more dramatic sensitivity. Digging deeper, he discovered the most sensitive had been regular green tea drinkers prior to the start of the study.

He then measured the polyphenol levels in saliva of people on days before, during and after they consumed several cups of green tea. This showed that saliva normally contains polyphenols, and there are large differences among individuals. Regular red wine and green tea drinkers had the highest levels. Drinking green tea was shown to elevate the saliva polyphenol levels.

"I would expect that red wine drinking would also, but we didn't demonstrate this," Siebert said.

The polyphenol level in saliva returns to an individual's baseline level within half an hour after consuming such beverages as coffee or tea; but over time, the underlying baseline level gradually rises with the continued consumption of tea.

"It appears that there is a metabolic pool of polyphenol that is influenced by dietary habits, and that the salivary polyphenol level influences perception of astringency caused by acids," Siebert said.

"This was the first demonstration that you normally have polyphenols in your saliva," he added. "That has some other implications, because the liquid in your saliva comes from the blood. So the long-term build-up must be in the blood."

This may help explain what has been labeled "the French paradox" -- the observation that French people have a relatively low incidence of heart disease, despite their diet rich in saturated fats. Some scientists believe it is due to their increased consumption of red wine, and have attributed it to the antioxidant benefits of polyphenols.

(Photo: Cornell U.)

Cornell University


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For the first time in history, a change will be made to the atomic weights of some elements listed on the periodic table of the chemical elements posted on walls of chemistry classrooms and on the inside covers of chemistry textbooks worldwide.

The new table, outlined in a report released this month, will express atomic weights of 10 elements - hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine and thallium - in a new manner that will reflect more accurately how these elements are found in nature.

“For more than a century and a half, many were taught to use standard atomic weights — a single value — found on the inside cover of chemistry textbooks and on the periodic table of the elements. As technology improved, we have discovered that the numbers on our chart are not as static as we have previously believed,” says Dr. Michael Wieser, an associate professor at the University of Calgary, who serves as secretary of the International Union of Pure and Applied Chemistry’s (IUPAC) Commission on Isotopic Abundances and Atomic Weights. This organization oversees the evaluation and dissemination of atomic-weight values.

Modern analytical techniques can measure the atomic weight of many elements precisely, and these small variations in an element’s atomic weight are important in research and industry. For example, precise measurements of the abundances of isotopes of carbon can be used to determine purity and source of food, such as vanilla and honey. Isotopic measurements of nitrogen, chlorine and other elements are used for tracing pollutants in streams and groundwater. In sports doping investigations, performance-enhancing testosterone can be identified in the human body because the atomic weight of carbon in natural human testosterone is higher than that in pharmaceutical testosterone.

The atomic weights of these 10 elements now will be expressed as intervals, having upper and lower bounds, reflected to more accurately convey this variation in atomic weight. The changes to be made to the Table of Standard Atomic Weights have been published in Pure and Applied Chemistry (http://iupac.org/publications/pac/asap/PAC-REP-10-09-14/) and a companion article in Chemistry International (http://www.iupac.org/publications/ci/2011/3302/1_coplen.html)

For example, sulfur is commonly known to have a standard atomic weight of 32.065. However, its actual atomic weight can be anywhere between 32.059 and 32.076, depending on where the element is found. “In other words, knowing the atomic weight can be used to decode the origins and the history of a particular element in nature,” says co-author Wieser of the Department of Physics and Astronomy.

Elements with only one stable isotope do not exhibit variations in their atomic weights. For example, the standard atomic weights for fluorine, aluminum, sodium and gold are constant, and their values are known to better than six decimal places.

“Though this change offers significant benefits in the understanding of chemistry, one can imagine the challenge now to educators and students who will have to select a single value out of an interval when doing chemistry calculations,” says Dr. Fabienne Meyers, associate director of IUPAC.

“We hope that chemists and educators will take this challenge as a unique opportunity to encourage the interest of young people in chemistry and generate enthusiasm for the creative future of chemistry.”

The University of Calgary has and continues to contribute substantially in the study of atomic weight variations. Professor H. Roy Krouse created the Stable Isotope Laboratory in the Department of Physics and Astronomy in 1971. Early work by Krouse established the wide natural range in the atomic weight of significant elements including carbon and sulfur. Currently, researchers at the University of Calgary in physics, environmental science, chemistry and geoscience are exploiting variations in atomic weights to elucidate the origins of meteorites, to determine sources of pollutants to air and water, and to study the fate of injected carbon dioxide in geological media.

This fundamental change in the presentation of the atomic weights is based upon work between 1985 and 2010 supported by IUPAC, the University of Calgary and other contributing Commission members and institutions.

University of Calgary


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The northernmost mummified forest ever found in Canada is revealing how plants struggled to endure a long-ago global cooling.

Researchers believe the trees -- buried by a landslide and exquisitely preserved 2 to 8 million years ago -- will help them predict how today’s Arctic will respond to global warming.

They also suspect that many more mummified forests could emerge across North America as Arctic ice continues to melt. As the wood is exposed and begins to rot, it could release significant amounts of methane and carbon dioxide into the atmosphere -- and actually boost global warming.

Joel Barker, a research scientist at Byrd Polar Research Center and the School of Earth Sciences at Ohio State University and leader of the team that is analyzing the remains, described early results at the American Geophysical Union meeting in San Francisco on Friday, December 17.

Over the summer of 2010, the researchers retrieved samples from broken tree trunks, branches, roots, and even leaves -- all perfectly preserved -- from Ellesmere Island National Park in Canada.

“Mummified forests aren’t so uncommon, but what makes this one unique is that it’s so far north. When the climate began to cool 11 million years ago, these plants would have been the first to feel the effects,” Barker said. “And because the trees’ organic material is preserved, we can get a high-resolution view of how quickly the climate changed and how the plants responded to that change.”

Barker found the deposit in 2009, when he was camping on Ellesmere Island for an unrelated research project. He followed a tip from a national park warden, who had noticed some wood sticking out of the mud next to a melting glacier. This summer, he returned with colleagues for a detailed study of the area.

Analysis of the remains has only just begun, but will include chemical and DNA testing.

For now, the researchers have identified the species of the most common trees at the site -- spruce and birch. The trees were at least 75 years old when they died, but spindly, with very narrow growth rings and under-sized leaves that suggest they were suffering a great deal of stress when they were alive.

“These trees lived at a particularly rough time in the Arctic,” Barker explained. “Ellesmere Island was quickly changing from a warm deciduous forest environment to an evergreen environment, on its way to the barren scrub we see today. The trees would have had to endure half of the year in darkness and in a cooling climate. That’s why the growth rings show that they grew so little, and so slowly.”

Colleagues at the University of Minnesota identified the wood from the deposit, and pollen analysis at a commercial laboratory in Calgary, Alberta revealed that the trees lived approximately 2 to 8 million years ago, during the Neogene Period. The pollen came from only a handful of plant species, which suggests that Arctic biodiversity had begun to suffer during that time as well.

The team is now working to identify other mummified plants at the site, scanning the remains under microscopes to uncover any possible seeds or insect remains.

Now that the forest is exposed, it’s begun to rot, which means that it’s releasing carbon into the atmosphere, where it can contribute to global warming.

Team member David Elliot, professor emeritus of earth sciences at Ohio State, said that the mummified forest on Ellesmere Island doesn’t pose an immediate threat to the environment, though.

“I want to be clear -- the carbon contained in the small deposit we’ve been studying is trivial compared to what you produce when you drive your car,” he said. “But if you look at this find in the context of the whole Arctic, then that is a different issue. I would expect other isolated deposits to be exposed as the ice melts, and all that biomass is eventually going to return to carbon dioxide if it’s exposed to the air.”

“It’s a big country, and unless people decide to walk all across the Canadian Arctic, we won’t know how many deposits are out there,” he added.

(Photo: Joel Barker, courtesy of Ohio State University)

Ohio State University


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Web users around the globe will be able to help professional astronomers in their search for Earth-like planets thanks to a new online citizen science project called Planet Hunters that launches Dec. 16. at www.planethunters.org.

Planet Hunters, which is the latest in the Zooniverse citizen science project collection, will ask users to help analyze data taken by NASA’s Kepler mission. The space telescope has been searching for planets beyond our own solar system—called exoplanets—since its launch in March 2009.

“The Kepler mission has given us another mountain of data to sort through,” said Kevin Schawinski, a Yale University astronomer and Planet Hunters co-founder. Schawinski also helped create the Galaxy Zoo citizen science project several years ago, which enlisted hundreds of thousands of web users around the world to help sort through and classify a million images of galaxies taken by a robotic telescope.

The Kepler space telescope is continually monitoring nearly 150,000 stars in the nearby constellation Cygnus, recording their brightness over time. Astronomers analyze these images, looking for any stars that show a slight dimming of their brightness. This dimming could represent a planet passing in front of its host star, blocking a tiny fraction of its light as seen from Kepler’s vantage point in space. Those stars that periodically dim are the best candidates for hosting relatively small planets that tightly orbit their stars, similar to Earth.

“The Kepler mission will likely quadruple the number of planets that have been found in the last 15 years, and it’s terrific that NASA is releasing this amazing data into the public domain,” said Debra Fischer, a Yale astronomer and leading exoplanet hunter. Although Planet Hunters is not tied directly to the Kepler mission, the website will serve as a complement to the work being done by the Kepler team to analyze the data.

Because of the huge amount of data being made available by Kepler, astronomers rely on computers to help them sort through the data and search for possible planet candidates. “But computers are only good at finding what they’ve been taught to look for,” said Meg Schwamb, another Yale astronomer and Planet Hunters co-founder. “Whereas the human brain has the uncanny ability to recognize patterns and immediately pick out what is strange or unique, far beyond what we can teach machines to do.”

After the success of the Galaxy Zoo project, the Yale team decided to enlist web users once again to create what they hope will become a global network of human computing power.

When users log on to the Planet Hunters website, they’ll be asked to answer a series of simple questions about one of the stars’ light curves—a graph displaying the amount of light emitted by the star over time—to help the Yale astronomers determine whether it displays a repetitive dimming of light, identifying it as an exoplanet candidate.

“The great thing about this project is that it gives the public a front row seat to participate in frontier scientific research,” Schwamb said.

The possibility of Earth-like planets beyond our own solar system has captured the collective human imagination for centuries. Today, astronomers have discovered more than 500 planets orbiting stars other than the Sun—yet almost all of these so-called exoplanets are large gas giants, similar to Jupiter, which bear little resemblance to Earth. Ever since the first exoplanet was discovered in 1995, astronomers have raced to find ever smaller planets closer to our own world.

“The search for planets is the search for life,” Fischer said. “And at least for life as we know it, that means finding a planet similar to Earth.” Scientists believe Earth-like planets are the best place to look for life because they are the right size and orbit their host stars at the right distance to support liquid water, an essential ingredient for every form of life found on Earth.

Yet Fischer is quick to caution that, even with the exceptional data from the Kepler telescope, it will be extremely difficult to pick out the weak signal created by such a small planet as it dims its host star. “Planet Hunters is an experiment—we’re looking for the needle in the haystack,” she said.

Still, Galaxy Zoo proved that ordinary people can make extraordinary discoveries. Several Galaxy Zoo users were listed as co-authors on more than 20 published scientific papers that resulted from the citizen science project, most of whom had no prior knowledge of astronomy.

“The point of citizen science is to actively involve people in real research,” Schawinski said. “When you join Planet Hunters, you’re contributing to actual science—and you might just make a real discovery.”

(Photo: Haven Giguere/Yale)

Yale University


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Caffeine consumption in children is often blamed for sleep problems and bedwetting. Information on childhood caffeine consumption is limited, and many parents may not know the amount or effects of their child's caffeine consumption. In a study published in The Journal of Pediatrics, researchers found that 75% of children surveyed consumed caffeine on a daily basis, and the more caffeine the children consumed, the less they slept.

Dr. William Warzak and colleagues from the University of Nebraska Medical Center surveyed the parents of over 200 children 5 to 12 years old during routine clinical visits at an urban pediatric clinic. Parents were asked to report the types and amounts of snacks and beverages their child consumed on a daily basis.

According to Dr. Warzak, "Some children as young as 5 years old were consuming the equivalent of a can of soda a day." The authors also noticed that the older children drank more caffeinated beverages. "Children between the ages of 8 and 12 years consumed an average of 109 mg a day," Dr. Warzak explains, "the equivalent of almost 3 12-ounce cans of soda."

Researchers found, however, that caffeine was not linked to bedwetting in these children. "Contrary to popular belief," Dr. Evans, coauthor and statistician, clarifies, "children were not more likely to wet the bed if they consumed caffeine, despite the fact that caffeine is a diuretic."

The study authors stress the importance of parental awareness regarding their child's caffeine consumption. "Parents should be aware of the potentially negative influence of caffeine on a child's sleep quality and daily functioning," Dr. Warzak asserts. The authors suggest that primary care pediatricians may be able to help by screening patients for caffeine consumption and educating parents about the potentially harmful effects of caffeine.

Elsevier Health Sciences


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Cold plasma jets could be a safe, effective alternative to antibiotics to treat multi-drug resistant infections, says a study published in the January issue of the Journal of Medical Microbiology on 15 December.

The team of Russian and German researchers showed that a ten-minute treatment with low-temperature plasma was not only able to kill drug-resistant bacteria causing wound infections in rats but also increased the rate of wound healing. The findings suggest that cold plasmas might be a promising method to treat chronic wound infections where other approaches fail.

The team from the Gamaleya Institute of Epidemiology and Microbiology in Moscow tested a low-temperature plasma torch against bacterial species including Pseudomonas aeruginosa and Staphylococcus aureus. These species are common culprits of chronic wound infections and are able to resist the action of antibiotics because they can grow together in protective layers called biofilms. The scientists showed not only that plasma was lethal to up to 99% of bacteria in laboratory-grown biofilms after five minutes, but also that plasma killed about 90 % of the bacteria (on average) infecting skin wounds in rats after ten minutes.

Plasmas are known as the fourth state of matter after solids, liquids and gases and are formed when high-energy processes strip atoms of their electrons to produce ionized gas flows at high temperature. They have an increasing number of technical and medical applications and hot plasmas are already used to disinfect surgical instruments.

Dr Svetlana Ermolaeva who conducted the research explained that the recent development of cold plasmas with temperatures of 35-40°C makes the technology an attractive option for treating infections. “Cold plasmas are able to kill bacteria by damaging microbial DNA and surface structures without being harmful to human tissues. Importantly we have shown that plasma is able to kill bacteria growing in biofilms in wounds, although thicker biofilms show some resistance to treatment.”

Plasma technology could eventually represent a better alternative to antibiotics, according to Dr Ermolaeva. “Our work demonstrates that plasma is effective against pathogenic bacteria with multiple-antibiotic resistance - not just in Petri dishes but in actual infected wounds,” she said. “Another huge advantage to plasma therapy is that it is non-specific, meaning it is much harder for bacteria to develop resistance. It’s a method that is contact free, painless and does not contribute to chemical contamination of the environment.”

Society for General Microbiology


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Deep sediment cores retrieved from the Bering Sea floor indicate that the region was ice-free all year and biological productivity was high during the last major warm period in Earth's climate history.

Christina Ravelo, professor of ocean sciences at the University of California, Santa Cruz, presented the new findings in a talk on December 13 at the fall meeting of the American Geophysical Union (AGU) in San Francisco. Ravelo and co-chief scientist Kozo Takahashi of Kyushu University, Japan, led a nine-week expedition of the Integrated Ocean Drilling Program (IODP) to the Bering Sea last summer aboard the research vessel JOIDES Resolution. The researchers drilled down 700 meters through rock and sludge to retrieve sediments deposited during the Pliocene Warm Period, 3.5 to 4.5 million years ago.

"Evidence from the Pliocene Warm Period is relevant to studies of current climate change because it was the last time in our Earth's history when global temperatures were higher than today," Ravelo said.

Carbon dioxide levels during the Pliocene Warm Period were also comparable to levels today, and average temperatures were a few degrees higher, she said. Climate scientists are interested in what this period may tell us about the effects of global warming, particularly in the polar regions. Current observations show more rapid warming in the Arctic compared to other places on Earth and compared to what was expected based on global climate models.

Ravelo's team found evidence of similar amplified warming at the poles during the Pliocene Warm Period. Analysis of the sediment samples indicated that average sea surface temperatures in the Bering Sea were at least 5 degrees Celsius warmer than today, while average global temperatures were only 3 degrees warmer than today.

Samples from the expedition showed evidence of consistently high biological productivity in the Bering Sea throughout the past five million years. The sediments contain fossils of plankton, such as diatoms, that suggest a robust ecology of organisms persisting from the start of the Pliocene Warm Period to the present. In addition, samples from the Pliocene Warm Period include deep-water organisms that require more oxygenated conditions than exist today, suggesting that the mixing of water layers in the Bering Sea was greater than it is now, Ravelo said.

"We usually think of the ocean as being more stratified during warm periods, with less vertical movement in the water column," she said. "If the ocean was actually overturning more during a period when it was warmer than today, then we may need to change our thinking about ocean circulation."

Today, the Bering Sea is ice-free only during the summer, but the sediment samples indicate it was ice-free year-round during the Pliocene Warm Period. According to Ravelo, the samples showed no evidence of the pebbles and other debris that ice floes carry from the land out to sea and deposit on the seafloor as they melt. In addition, the researchers didn't find any of the microorganisms typically associated with sea ice, she said.

"The information we found tells us quite a bit about what things were like during the last period of global warming. It should benefit the scientists today who are sorting out how ocean circulation and conditions at the poles change as the Earth warms," Ravelo said.

The expedition led by Ravelo and Takahashi was part of an ongoing program conducted by the IODP with funding from the National Science Foundation and support from the United States, Japan, and the European Union. The JOIDES Resolution is the only ship operated by the United States capable of taking undisturbed core samples at the depths required to study conditions during the Pliocene Warm Period. The current program will end in 2013, and planning for the next phase of ocean drilling is now under way.

(Photo: Carlos Alvarez Zarikian, IODP/TAMU)

University of California, Santa Cruz


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As space-based probes and telescopes reveal new and unimaginable features of our universe, a geological landmark on Saturn's moon Iapetus is among the most peculiar.

Images provided by NASA's Cassini spacecraft in 2005 reveal an almost straight-line equatorial mountain range that towers upwards of 12 miles and spreads as wide as 60 miles, encircling more than 75 percent of Iapetus, the ringed planet's third-largest moon, and causing it to resemble a walnut.

"There's nothing else like it in the solar system," said Andrew Dombard, associate professor of earth and environmental sciences at the University of Illinois at Chicago. "It's something we've never seen before and didn't expect to see."

Some scientists have hypothesized that Iapetus's mountains were formed by internal forces such as volcanism, but Dombard, along with Andrew Cheng, chief scientist in the space department at the Johns Hopkins University Applied Physics Laboratory, William McKinnon, professor of earth and planetary sciences at Washington University in St. Louis and Jonathan Kay, a UIC graduate student studying with Dombard, think the mountains resulted from icy debris raining down from a sub-satellite or mini-moon orbiting Iapetus, which burst into bits under tidal forces of the larger moon.

"Imagine all of these particles coming down horizontally across the equatorial surface at about 400 meters per second -- the speed of a rifle bullet, one after another, like frozen baseballs," said McKinnon. "At first the debris would have made holes to form a groove that eventually filled up."

Dombard and his collaborators think the phenomenon is the result of what planetary scientists call a giant impact, where crashing and coalescing debris during the solar system's formation more than 4 billion years ago created satellites such as the Earth's Moon and Pluto's largest satellite Charon.

They've done a preliminary analysis demonstrating the plausibility of impact formation and subsequent evolution of Iapetus's sub-satellite. Dombard said Iapetus is the solar system's moon with the largest "hill sphere" -- the zone surrounding a moon where the gravitational force is stronger than that of the planet it circles.

"It is the only moon far enough from its planet, and large enough relative to its planet, that a giant impact may be able to form a sub-satellite," said Cheng.

This lends plausibility to the rain of debris along the equator hypothesis, Dombard said, but he adds that more sophisticated computer modeling and analysis is planned in the coming years to back it up.

Other explanations have been proposed by scientists as to what caused this odd formation of mountains on Iapetus, but Dombard said they all have shortcomings.

"There are three critical observations that you need to explain," he said. "Why the mountains sit on the equator, why it's found only on the equator, and why only on Iapetus? Previous models address maybe one or two of those critical observations. We think we can explain all three."

University of Illinois at Chicago


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A new University of Florida study to be published online in the Proceedings of the National Academy of Sciences presents the deepest insight to the genes that made up the first flower, the common ancestor of all flowering plants, and how those genes have changed over time.

“Our survival depends on products we get from the flower — grains, fruits and many other materials,” said Doug Soltis, UF distinguished professor of biology and project co-investigator. “Crop improvement is so important, but you don’t understand how a flower is put together unless you have a reference point – you can’t modify what you can’t understand.”

After nearly 10 years of research funded by the National Science Foundation, scientists from the Florida Museum of Natural History, the UF department of biology, and the UF Genetics Institute are bringing the study to a close.

“There are 350,000 species of flowering plants (or angiosperms), and they serve as the foundation of nearly all of Earth’s ecosystems, yet we don’t know how the flower originated,” said Pam Soltis, UF distinguished professor, Florida Museum of Natural History curator and project co-investigator. “We now know the origin of many of the genes responsible for making a flower and how those genes have changed during the history of angiosperms.”

A 2009 UF study traced the origin of flowers using genetic data for the avocado (a representative of one of the early lineages of flowering plants) and a well-known plant in genetics research, Arabidopsis thaliana. The new study includes additional comparisons with a water lily, California poppy and cycad (a gymnosperm or non-flowering seed plant) and shows how the first flowers evolved from pre-existing genetic programs in gymnosperm cones.

“We have a much better understanding of the flower than we did 10 years ago and it’s a huge improvement,” Doug Soltis said. “We don’t know every pathway, but we have a much better handle on what makes those parts tick.”

Typical angiosperms have flowers with four organs: sepals (typically green), petals (typically colorful), stamens (male organs, which produce pollen) and carpels (female organs, which produce eggs). But in the earliest flowers, the distinct borders between their floral organs fade to a blur. The flowers of early angiosperms have organs that merge into each other – for example, a stamen of a water lily produces pollen but it may also be petal-like and colorful.

“Our study found that the floral organs of basal angiosperms merge not only in appearance, but also in their underlying genetic pathways,” Pam Soltis said. “During evolution, the timing and location of where these genes act have become restricted, ultimately producing flowers with separate and distinguishable flower parts.”

“These missing links are incredibly important,” Doug Soltis said. “They are our key to the past.”

The study was a collaboration of researchers at UF, The Pennsylvania State University, the University of Georgia, and the University at Buffalo. The first author on the paper is Andre Chanderbali, a postdoctoral student at the Florida Museum and the UF department of biology.

“Flowers are the defining feature of angiosperms, the dominant vegetation of our world,” said Stanford University biology professor Virginia Walbot. “The new PNAS article by Chanderbali et al. represents a breakthrough in understanding the origin and evolutionary trajectories of the separate male and female floral parts.”

University of Florida




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