Thursday, July 31, 2008

Amber Fossils Reveal Ancient France Was A Jungle


Research on a treasure trove of amber has yielded evidence that France once was covered by a dense tropical rainforest with trees similar to those found in the modern-day Amazon. The 55-million-year-old pieces of amber was discovered in the Oise River area in northern France.

In the new study, Akino Jossang and colleagues used
laboratory instruments to analyze the fossilized tree sap in an effort to link specific samples of amber to specific kinds of trees. The amber remained intact over the ages, while the trees from which it oozed disappeared. Efforts to make such connections have been difficult because amber from different sites tended to have very similar chemical compositions.

The report describes discovery of a new organic compound in amber called "quesnoin," whose precursor exists only in sap produced by a tree currently growing only in Brazil's Amazon rainforest.

Researchers say that amber probably seeped out of a similar tree growing in a tropical forest that covered France millions of years ago before Earth's continents drifted into their current positions.

"The region corresponding to modern France could have been found in a geographically critical marshy zone belonging to Africa and a tropical zone 55 million years ago extending through North Africa to the Amazon," the report states.

The study "Quesnoin, a Novel Pentacyclic ent-Diterpene from 55 Million Year Old Oise Amber" is scheduled for the Jan. 4 issue of ACS' Journal of Organic Chemistry.


SOURCE : American Chemical Society


Gorillas In The Midst Of Extinction

Satellites provide a bird's eye view of planet Earth, and the space-based vantage can be extremely useful to people interested in viewing out-of-the-way places. Conservationists, for example, must monitor far-flung areas in need of protection. Wars, poverty, remoteness, lack of government involvement, and uncertainty over the best places and ways to focus limited resources can all hinder conservation efforts. Now, NASA satellite imagery is giving scientists and conservationists some of the tools they need to get valuable information on land cover and land use changes in wild areas.


This map shows the location of the Virunga Conservation area within Africa,
and highlights an area in the "Mikeno" sector of the park where rapid deforestation occurred in June 2004. (Credit: Nadine Laporte/ Tiffany Lin)


NASA satellite imagery helps scientists better understand land changes in the Virunga Conservation Area which covers the Virunga National Park in the Democratic Republic of Congo (DRC), the Mgahinga Gorilla National Park in Uganda and the Volcanoes National Park in Rwanda. In Swahili, the word virunga means volcano. The Virunga Conservation Area offers habitat to 380 of the world's 700 remaining mountain gorillas. The other 320 gorillas reside in the nearby Bwindi Impenetrable National Park in Uganda.

In a single week in June of 2004, farmers created pasture for their cattle by clearing 15 square kilometers (5.8 square miles), or 6 percent, of the 264-square kilometers (102 square miles) of mountain gorilla habitat in the southern "Mikeno" sector of Virunga National Park. Because mountain gorilla numbers had increased by close to 56 individuals over the last 10 years, the recent loss of land was a considerable step backward.

In a race against time for the mountain gorillas and many other species indigenous to these natural areas, scientists at the Woods Hole Research Center (WHRC) in Woods Hole, MA, are working with NASA and conservationists in the Virunga National Park to stave off further destruction of the lands.

"Remote sensing is the only tool that we have to efficiently monitor these remote parks," says Nadine Laporte, head of the Africa Program at WHRC. "Satellite imagery allows park managers to update park property boundaries, map forest habitat, and look at encroachment of the park by comparing images from two different dates."

Laporte is working with conservation groups to create a monitoring system that combines NASA satellite imagery with aerial flight and field surveys, all of which can be relayed to and coordinated with local park rangers on the ground. Currently, park workers are building a three-foot wall along key park borders to keep out cattle and people seeking to alter the land.

NASA now provides free Landsat images, which researchers and rangers are using as base maps for field surveys. "We still have to integrate remote sensing with traditional surveys on the ground," said Laporte. "They really complement each other. The rate of change is so rapid that we need satellite imagery in a timely fashion to address the problems in the area. Aerial imagery is too expensive."

Since gorilla habitat crosses three different countries, satellite imagery provides data and perspectives that are not bound by political borders. The satellite images can create a convenient method for exchanging information among the three parks that make up the Virunga Conservation Area.

Along with mapping and monitoring changes in forest cover, a time-sensitive series of images can allow researchers to estimate rates and patterns of deforestation in and around protected areas. These patterns are also studied in relation to trends in human migration.

###

The Africa Program at the Woods Hole Research Center is funded though NASA's Land Cover Land Use Change program, the US Agency for International Development (USAID), and the Wildlife Conservation Society.


SOURCE : National Aeronautics And Space Administration


Brown Argus Butterfly Sees Positive Effects Of Climate Change



ScienceDaily (June 9, 2008) — Global warming is generally thought to have a negative affect on the habitats of many animals and plants. Not for the Brown Argus butterfly, however. This insect seems to be bucking the trend and expanding its numbers quicker and more effectively, according to new research. agestis has expanded northwards in Britain during the last 30 years. It is thought that the recent expansion of the species is due to the increasing summer temperatures caused by global warming.


The Brown Argus butterfly Aricia agestis has expanded northwards in Britain during the last 30 years.
It is thought that the recent expansion of the species is due to the increasing summer temperatures caused
by global warming. (Credit: iStockphoto/Pauline Mills)


Research carried out by scientists in the UK and Spain reveals that by moving into new areas, the Brown Argus may be escaping from some of its 'natural enemies' (parasitoids).

This is not because natural enemies are absent from the new areas, but that the parasitoids are not able to locate the Brown Argus. Instead, the parasitoids rely on the common blue butterfly Polyommatus icarus in these northern habitats. This species has a long-established range throughout Britain and suffers a larger amount of parasitism than the Brown Argus in these northern habitats.

Although the researchers cannot yet say for certain why the Brown Argus has fewer parasites in its new range, they suggest it could be due to the differences between the plants that the caterpillars eat. The common blue and brown argus feed on different plants and therefore the parasitoids are used to looking for caterpillars on the common blue's favourite plants.

Dr Rosa Menendez said: "Climate change can have unpredicted consequences by altering the interaction between species and their enemies, whilst in this case the butterfly may be a welcome addition in other cases the release from enemies might favour pests or other unwanted species".


SOURCE : Wiley-Blackwell


Wednesday, July 30, 2008

Insect Attack May Have Finished Off Dinosaurs



Asteroid impacts or massive volcanic flows might have occurred around the time dinosaurs became extinct, but a new arguemet is that the mightiest creatures the world has ever known may have been brought down by a tiny, much less dramatic force -- biting, disease-carrying insects.

An important contributor to the demise of the dinosaurs, experts say, could have been the rise and evolution of insects, especially the slow-but-overwhelming threat posed by new disease carriers. And the evidence for this emerging threat has been captured in almost lifelike-detail -- many types of insects preserved in amber that date to the time when dinosaurs disappeared.

"There are serious problems with the sudden impact theories of dinosaur extinction, not the least of which is that dinosaurs declined and disappeared over a period of hundreds of thousands, or even millions of years," said George Poinar Jr., a courtesy professor of zoology at Oregon State University. "That time frame is just not consistent with the effects of an asteroid impact. But competition with insects, emerging new diseases and the spread of flowering plants over very long periods of time is perfectly compatible with everything we know about dinosaur extinction."


Tick found in Burmese amber. (Credit: Image courtesy of Oregon State University)


This concept is outlined in detail in "What Bugged the Dinosaurs? Insects, Disease and Death in the Cretaceous," a book by George and Roberta Poinar, just published by Princeton University Press.

In it, the authors argue that insects provide a plausible and effective explanation for the slow, inexorable decline and eventual extinction of dinosaurs over many thousands of years. This period is known as the famous "K-T Boundary," or the line between the Cretaceous and Tertiary Period about 65 million years ago. There is evidence that some catastrophic events, such as a major asteroid or lava flows, also occurred at this time -- but these provide no complete explanation for the gradual decline of dinosaur populations, and even how some dinosaurs survived for thousands of years after the K-T Boundary.

Insects and disease, on the other hand, may have been a lot slower, but ultimately finished the job.

"We don't suggest that the appearance of biting insects and the spread of disease are the only things that relate to dinosaur extinction," Poinar said. "Other geologic and catastrophic events certainly played a role. But by themselves, such events do not explain a process that in reality took a very, very long time, perhaps millions of years. Insects and diseases do provide that explanation."

Poinar and his wife, Roberta, have spent much of their careers studying the plant and animal life forms found preserved in amber, using them to re-create the biological ecosystems that were in place millions of years ago. They are also authors of "The Amber Forest: A Reconstruction of a Vanished World."

As a semi-precious gem that first begins to form as sap oozing from a tree, amber has the unique ability to trap very small animals or other materials and -- as a natural embalming agent -- display them in nearly perfect, three-dimensional form millions of years later. This phenomenon has been invaluable in scientific and ecological research, and among other things, formed the scientific premise for the movie Jurassic Park, for the "dinosaur DNA" found in mosquitoes.

"During the late Cretaceous Period, the associations between insects, microbes and disease transmission were just emerging," Poinar said. "We found in the gut of one biting insect, preserved in amber from that era, the pathogen that causes leishmania -- a serious disease still today, one that can infect both reptiles and humans. In another biting insect, we discovered organisms that cause malaria, a type that infects birds and lizards today.

"In dinosaur feces, we found nematodes, trematodes and even protozoa that could have caused dysentery and other abdominal disturbances. The infective stages of these intestinal parasites are carried by filth-visiting insects."

In the Late Cretaceous, Poinar said, the world was covered with warm-temperate to tropical areas that swarmed with blood-sucking insects carrying leishmania, malaria, intestinal parasites, arboviruses and other pathogens, and caused repeated epidemics that slowly-but-surely wore down dinosaur populations. Ticks, mites, lice and biting flies would have tormented and weakened them.

"Smaller and separated populations of dinosaurs could have been repeatedly wiped out, just like when bird malaria was introduced into Hawaii, it killed off many of the honeycreepers," Poinar said. "After many millions of years of evolution, mammals, birds and reptiles have evolved some resistance to these diseases. But back in the Cretaceous, these diseases were new and invasive, and vertebrates had little or no natural or acquired immunity to them. Massive outbreaks causing death and localized extinctions would have occurred."

In similar fashion, the researchers suggest, insects would have played a major role in changing the nature of plant life on Earth -- the fundamental basis for all dinosaur life, whether herbivore, omnivore or carnivore. As the dinosaurs were declining, their traditional food items such as seed ferns, cycads, gingkoes and other gymnosperms were largely being displaced by flowering plants, which insects helped spread by their pollination activities. These plants would have spread to dominate the landscape. Also, insects could have spread plant diseases that destroyed large tracts of vegetation, and the insects could have been major competitors for the available plant food supply.

"Insects have exerted a tremendous impact on the entire ecology of the Earth, certainly shaping the evolution and causing the extinction of terrestrial organisms," the authors wrote in their book. "The largest of the land animals, the dinosaurs, would have been locked in a life-or-death struggle with them for survival."

The confluence of new insect-spread diseases, loss of traditional food sources, and competition for plants by insect pests could all have provided a lingering, debilitating condition that dinosaurs were ultimately unable to overcome, the researchers say. And these concerns -- which might have pressured the dinosaurs for thousands of years -- may have finished the job, along with the changing environment, meteor impacts and massive lava flows.

"We can't say for certain that insects are the smoking gun, but we believe they were an extremely significant force in the decline of the dinosaurs," Poinar said. "Our research with amber shows that there were evolving, disease-carrying vectors in the Cretaceous, and that at least some of the pathogens they carried infected reptiles. This clearly fills in some gaps regarding dinosaur extinctions."


SOURCE : Oregon State University


Leaf Age May Contribute To Contamination Of Lettuce With E. Coli And Salmonella



A new study presents the first evidence that harmful pathogens frequently linked with food-borne illnesses are more commonly found on younger inner leaves than on older outer leaves of romaine lettuce. The researchers from the Produce Safety and Microbiology Research Unity, Albany, California and the University of California, Berkley report their findings in the journal Applied and Environmental Microbiology.

Lettuce (Lactuca sativa) is the fresh produce item most commonly implicated in epidemics of food-borne illness, while Escherichia coli O157:H7 and Salmonella enterica are the most frequently attributed bacterial agents. Although previous studies have focused on E. coli O157:H7 colonization on cut or shredded lettuce leaves, little is known of its ability to colonize whole lettuce leaves in both pre- and post-harvest environments.

In the study researchers investigated the growth of E. coli O157:H7 and S. enterica on romaine lettuce leaves both pre- and post-harvest. The increased population size of E. coli O157:H7 on young lettuce plants ranged from 16- to 100-fold in the presence of warm temperatures and free water on the leaves.

The increase in population size also varied significantly with leaf age, however the colonization was consistently 10-fold higher on the young (inner) leaves than on the middle leaves. Growth rates of S. enterica were found to be similarly leaf age dependent. Both bacterial pathogens also displayed higher population rates on younger leaves than on middle leaves harvested from mature lettuce heads.

"Our results indicate that leaf age and nitrogen content contribute to shaping the bacterial communities of preharvest and postharvest lettuce and that young lettuce leaves may be associated with a greater risk of contamination with E. coli O157:H7.

Journal reference: M.T. Brandl, R. Amundson. 2008. Leaf age as a risk factor in contamination of lettuce with Escherichia coli O157:H7 and Salmonella enterica. Applied and Environmental Microbiology, 74. 8: 2298-2306.


SOURCE : American Society for Microbiology


How Cranberry Juice Can Prevent Urinary Tract Infections



For generations, people have consumed cranberry juice, convinced of its power to ward off urinary tract infections, though the exact mechanism of its action has not been well understood. A new study by researchers at Worcester Polytechnic Institute (WPI) reveals that the juice changes the thermodynamic properties of bacteria in the urinary tract, creating an energy barrier that prevents the microorganisms from getting close enough to latch onto cells and initiate an infection.

The study, published in the journal Colloids and Surfaces: B, was conducted by Terri Camesano, associate professor of chemical engineering at WPI, and a team of graduate students, including PhD candidate Yatao Liu. They exposed two varieties of E. coli bacteria, one with hair-like projections known as fimbriae and one without, to different concentrations of cranberry juice. Fimbriae are present on a number of virulent bacteria, including those that cause urinary tract infections, and are believed to be used by bacteria to form strong bonds with cells.

For the fimbriaed bacteria, they found that even at low concentrations, cranberry juice altered two properties that serve as indicators of the ability of bacteria to attach to cells. The first factor is called Gibbs free energy of attachment, which is a measure of the amount of energy that must be expended before a bacterium can attach to a cell. Without cranberry juice, this value was a negative number, indicating that energy would be released and attachment was highly likely. With cranberry juice the number was positive and it grew steadily as the concentration of juice increased, making attachment to urinary tract cells increasingly unlikely.

Surface free energy also rose, suggesting that the presence of cranberry juice creates an energy barrier that repels the bacteria. The researchers also placed the bacteria and urinary tract cells together in solution. Without cranberry juice, the fimbriaed bacteria attached readily to the cells. As increasing concentrations of cranberry juice were added to the solution, fewer and fewer attachments were observed.

Cranberry juice had no discernible effect on E. coli bacteria without fimbriae, suggesting that compounds in the juice may act directly on the molecular structure of the fimbriae themselves. This reinforces previous work by the WPI team that showed that exposure to cranberry juice alters the shape of the fimbriae, causing them to become compressed. Using an atomic force microscope as a minute strain gauge, the team also showed that the adhesive force exerted by bacteria on urinary tract cells declined in direct proportion to the concentration of cranberry juice in the solution.

"Our results show that, at least for urinary tract infections, cranberry juice targets the right bacteria--those that cause disease--but has no effect on non-pathogenic organisms, suggesting that cranberry juice will not disrupt bacteria that are part of the normal flora in the gut," Camesano says. "We have also shown that this effect occurs at concentrations of cranberry juice that are comparable to levels we would expect to find in the urinary tract."

Camesano notes that unpublished work has shown that while cranberry juice has potent effects on disease-causing bacteria, those effects are transitory. "When we takes E. coli. bacteria that have been treated with cranberry juice and place them in normal growth media, they regain the ability to adhere to urinary tract cells," she says. "This suggests that to realize the antibacterial benefits of cranberry, one must consume cranberry juice regularly--perhaps daily."

For those watching calories, Camesano says other recent work in her lab has shown that the effects of regular cranberry juice cocktail and diet (sugar-free) cranberry juice are identical. "That's good news for people who do not like to consume a lot of sugary juice," she says.


SOURCE : Worcester Polytechnic Institute


Tuesday, July 29, 2008

New Invention Effectively Kills Foodborne Pathogens In Minutes




Scanning electron micrograph of highly magnified Salmonella infantis bacteria.
(Credit: CDC/Janice Carr)




University of Georgia researchers have developed an effective technology for reducing contamination of dangerous bacteria on food. The new antimicrobial wash rapidly kills Salmonella and E. coli O157:H7 on foods ranging from fragile lettuce to tomatoes, fruits, poultry products and meats. It is made from inexpensive and readily available ingredients that are recognized as safe by the U.S. Food and Drug Administration.

The new technology, which has commercial application for the produce, poultry, meat and egg processing industries, is available for licensing from the University of Georgia Research Foundation, Inc., which has filed a patent application on the new technology.

The Centers for Disease Control and Prevention estimates that, in the U.S. alone, foodborne pathogens are responsible for 76 million illnesses every year. Of the people affected by those illnesses, 300,000 are hospitalized and more than 5,000 die. These widespread outbreaks of food-borne illnesses are attributed, in part, to the fast-paced distribution of foods across the nation. Recently, raw tomatoes caused an outbreak of salmonellosis that sickened more than 300 people in at least 28 states and Canada.

Currently, a chlorine wash is frequently used in a variety of ways to reduce harmful bacteria levels on vegetables, fruits and poultry, but because of chlorine's sensitivity to food components and extraneous materials released in chlorinated water treatments, many bacteria survive. Chlorine is toxic at high concentrations, may produce off-flavors and undesirable appearance of certain food products, and it can only be used in conjunction with specialized equipment and trained personnel. In addition, chlorine may be harmful to the environment.

"We can't rely on chlorine to eliminate pathogens on foods," said Michael Doyle, one of the new technology's inventors and director of UGA's Center for Food Safety. "This new technology is effective, safe for consumers and food processing plant workers, and does not affect the appearance or quality of the product. It may actually extend the shelf-life of some types of produce."

Doyle is an internationally recognized authority on food safety whose research focuses on developing methods to detect and control food-borne bacterial pathogens at all levels of the food continuum, from the farm to the table. He has served as a scientific advisor to many groups, including the World Health Organization, the Food and Drug Administration, the U.S. Department of Agriculture, the U.S. Department of Defense and the U.S. Environmental Protection Agency.

The new antimicrobial technology, developed by Doyle and Center for Food Safety researcher Tong Zhao, uses a combination of ingredients that kills bacteria within one to five minutes from application. It can be used as a spray and immersion solution, and its concentration can be adjusted for treatment of fragile foods such as leafy produce, more robust foods such as poultry, or food preparation equipment and food transportation vehicles.

"The effectiveness, easy storage and application, and low cost of this novel antibacterial make it applicable not only at food processing facilities, but also at points-of-sale and at home, restaurants and military bases. The development of this technology is timely, given the recent, sequential outbreaks of foodborne pathogens," said Gennaro Gama, UGARF technology manager in charge of licensing this technology.



SOURCE : University of Georgia



Protozoa May Enable Food-Borne Pathogens On Leafy Vegetables


Protozoa found on lettuce and spinach may sequester harmful food-borne pathogens ultimately contributing to their survival on produce surfaces say researchers from Tennessee Technological University, Cookeville and the Produce Safety and Microbiology Research Unit, Albany, California.

Several outbreaks of food-borne illnesses attributed to Escherichia coli O157:H7 and Salmonella enterica have received national attention in recent years. The Centers for Disease Control and Prevention reported that fresh produce was the most significant source of food-borne illness in 2005.

Protozoa are single-celled organisms whose main function is bacterial consumption. They are commonly found in the natural microflora of plants and several species of amoebae have been associated with fresh salad vegetables. The recent occurrence of multiple outbreaks has encouraged researchers to further examine the interaction between food-borne pathogens and protozoa.

In the study protozoa (Glaucoma sp., Colpoda steinii, and Acanthamoeba palestinensis) as well as the soil-borne strain, Tetrahymena pyriformis, were cultured from store-bought spinach and lettuce and washed and allowed to graze on green fluorescent protein- or red fluorescent protein-labeled enteric pathogens including E. coli O157:H7, S. enterica, and Listeria monocytogenes.

They were then monitored for their ability to sequester the bacteria and for vesicle production (food vacuoles released by protozoa offering a means of protection to some bacteria). Results showed Glaucoma produced vesicles with all bacterial strains and Tetrahymena also displayed vesicle production, but only of E. coli O157:H7 and S. enterica, not L. monocytogenes. Further studies of E. coli O157:H7 following vesicle production revealed that 4 hours after the addition of spinach extract, the bacteria had multiplied and escaped the vesicles. C. steinii did not produce any vesicles from any of the pathogens.

"The presence of protozoa on leafy vegetables and their sequestration of enteric bacteria in vesicles indicate that they may play an important role in the ecology of human pathogens on produce," say the researchers.

Journal reference: P. Gourabathini, M.T. Brandl, K.S. Redding, J.H. Gunderson, S.G. Berk. 2008. Interactions between food-borne pathogens and protozoa isolated from lettuce and spinach. Applied and Environmental Microbiology, 74. 8: 2518-2525.


SOURCE : American Society for Microbiology


Milkweed's Evolutionary Approach To Caterpillars: Counter Appetite With Fast Repair



The adage that your enemies know your weaknesses best is especially true in the case of plants and predators that have co-evolved: As the predators evolve new strategies for attack, plants counter with their own unique defenses.

Milkweed is the latest example of this response, according to Cornell research suggesting that plant may be shifting away from elaborate defenses against specialized caterpillars toward a more energy-efficient approach. Genetic analysis reveals an evolutionary trend for milkweed plants away from resisting predators to putting more effort into repairing themselves faster than caterpillars -- particularly the monarch butterfly caterpillar -- can eat them.

"An important question with co-evolution is where does it end?" said Anurag Agrawal, Cornell associate professor of ecology and evolutionary biology and lead author of a paper in the current issue of the Proceedings of the National Academy of Sciences. "One answer is when it becomes too costly. Some plants seem to have shifted away from resisting herbivory [plant eating] and have taken that same energy and used it to repair themselves."

The paper is important because it sheds light on key theories of co-evolution, claiming that pressure by foraging insects makes plants diversify as they evolve new defensive strategies and that such diversification follows trends in one direction or another, said Agrawal.

Milkweed species have evolved elaborate resistance strategies to fight off caterpillars that eat their leaves. These include hairs on their leaves, heart poisons called cardenolides in their tissues and milky-white toxic latex that pours from the plants' tubes. A caterpillar's bite into a milkweed leaf leads to a flood of latex that is "like getting a gallon of sticky paint thrown into your face," said Agrawal.

Some caterpillars, in turn, have adapted by shaving the leaf, cutting a leaf's veins in a circle and then eating in the middle where the latex doesn't flow. Also, the monarch caterpillar has become immune to the cardenolides.

Using DNA sequence data to look at relationships between 38 species of milkweed, Agrawal and colleague Mark Fishbein, a Portland State University biologist, found evolutionary declines in milkweed's three most important resistance traits (hairs, cardenolides and latex) and an escalation in the plant's ability to regrow.

Agrawal was surprised, he said, to find that the plant became more tolerant rather than more diverse in its defenses. The reason, he speculated, could be because as its predators have become so specialized, the plant was better off choosing a new defensive tactic "to tolerate the herbivory damage instead of resisting it." It is unknown whether such strategies have also evolved in animals trying to evade parasites.

The findings address questions about plant evolution, biodiversity and keystone species and may give plant scientists clues about profitable pest control strategies.

The study was funded by the National Science Foundation.


SOURCE : Cornell University


Monday, July 28, 2008

Dinosaurs Did Not Evolve Quickly In Last 50 Million Years, New Dinosaur Super-tree Shows



It has long been debated whether dinosaurs were part of the ‘Terrestrial Revolution’ that occurred some 100 million years ago during the Cretaceous when birds, mammals, flowering plants, insects and reptiles all underwent a rapid expansion.


Super-tree of dinosaurs with 440 species listed.
(Credit: Image courtesy of Graeme Lloyd, Bristol University)


An international study, led by the University of Bristol, shows that during their last 50 million years of existence, dinosaurs were not expanding as actively as had been previously thought and that the apparent explosion of dinosaur diversity may be largely explained by sampling bias.

The team produced a ‘supertree’ of dinosaurs, showing the most likely pattern of evolution for 440 of the 600 known species of dinosaur. "Supertrees are very large family trees made using sophisticated computer techniques that carefully stitch together several smaller trees which were previously produced by experts on the various subgroups”, explained lead author Graeme Lloyd.

“Our supertree summarises the efforts of two decades of research by hundreds of dinosaur workers from across the globe and allows to look for unusual patterns across the whole of dinosaurs for the first time." It is the most comprehensive picture ever produced of how dinosaurs evolved.

Professor Mike Benton from Bristol University said: "It's not complete, but it's the most detailed and comprehensive single evolutionary tree produced for dinosaurs, and indeed for almost any other group.

"Up until now, most studies of the evolution of dinosaurs were not tested numerically against an accurate and comprehensive database. We hope our study will mark the first of a new wave of such thorough, quantitative studies in palaeontology."

The new study uses statistical techniques to distinguish unusually high rates of diversification from normal rates. The results show that all the bursts of diversification happened in the first fifty million years of the evolution of dinosaurs. Later expansions were not distinguishable from normal rates. This suggests dinosaurs did not take advantage of the new food supplies available during the Cretaceous Terrestrial Revolution – such as flowering plants, lizards, snakes, birds and mammals.

The work was done using the High Performance Computing facilities of the National University of Ireland, Maynooth. It was based on a combination of 155 published dinosaur ‘trees’ and took approximately 5,000 hours of calculation time.

The key focus was to see whether dinosaurs had been part of a major phase of evolution on land – the Cretaceous Terrestrial Revolution (between 125–80 million years ago) – when many new groups of plants and animals expanded rapidly. During this time, the flowering plants and social insects arose and became more and more common. Many backboned animals also expanded to take advantage of the new sources of food.


SOURCE : Bristol University



Pollination Habits Of Endangered Texas Rice Revealed To Help Preservation



A type of wild rice that only grows in a small stretch of the San Marcos River is likely so rare because it plays the sexual reproduction game poorly, a study led by the Lady Bird Johnson Wildflower Center at The University of Texas at Austin has revealed.


Aerial stems (culms) of Texas wild-rice.
(Credit: Flo Oxley, director of conservation at the Lady Bird Johnson Wildflower Center
at The University of Texas at Austin.)



The first study of breeding habits of this endangered, aquatic grass (Zizania texana) found that the pollen of Texas wild-rice can only travel about 30 inches away from a parent plant. If pollen doesn't land on a receptive female flower within that distance, no seeds will be produced. No seeds means no new plants to replenish a population that faces other survival threats.

"It would be great to introduce more of these plants into the San Marcos River so that we can build up its population, said Flo Oxley, conservation director at the Wildflower Center, and lead author of the study.

"This information will be useful when reintroduction efforts begin, because we now know that lots of new plants must be planted close together in order for seeds to be produced."

The findings were published in June in The Southwestern Naturalist journal of the Southwestern Association of Naturalists, and shared with staff at the U.S. Fish and Wildlife Service and the Texas Parks and Wildlife Department.

The U.S. Fish and Wildlife Service is the principal federal agency responsible for federally listed species conservation. Texas has about 25 percent of the plant biodiversity nationally, including 23 endangered and five threatened plant species.

Texas wild-rice prefers the clean, clear water of the San Marcos River and is not found anywhere else. The plant spends most of its life submerged, emerging only to flower. Recreation on the river can stir up sediments that prevent sunlight from reaching the plants, and swimmers, tubers and canoers often submerge the plants' flowers so they can't pollinate. This foot traffic isn't expected to go away soon, and the flow of underground water into springs that feed the river is also decreasing as the Central Texas population expands and drinking water needs increase.

"Nobody intends to shut down access to the river because of these plants" Oxley said, "and I've been surprised at how respectful of the plant people are when they learn that it is an endangered species that grows only in the San Marcos River and nowhere else in the world. Texans are very proud and protective of their natural history, and I believe they will take care of Texas wild-rice if we just let them know about it."

It doesn't hurt, she added, that Texas wild-rice serves as home for tiny invertebrates that have nasty feeding habits.

"People who swim through Texas wild-rice risk picking up these aquatic hitchhikers and may end up with itchy behinds for their efforts," she said.

Texas wild-rice is a food source and home for endangered fish called fountain darters, and is a cousin to several rice species cultivated for food purposes. But it is among more than 200 plant species of concern in Texas whose fundamental value isn't understood because so little information has been available to guide conservation or other decisions.

"We don't know what overall purpose this plant serves in the ecosystem, and we don't know what's going to happen if this plant goes away, Oxley said.

"To paraphrase what Aldo Leopold once said, ‘Whenever you tinker with Nature, be sure to keep all the parts.' Texas wild-rice is definitely one of those important parts."


SOURCE : University of Texas at Austin


Controlling Invasive Cane Grass With Wasps?



Researchers at The University of Texas at Austin will work with the U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS) to investigate biological control for an invasive cane grass that is choking waterways across North America.



Also known as Carrizo and giant cane, the grass is growing along extensive stretches of the Rio Grande in Texas and can be found along Austin waterways such as Shoal Creek. It grows up to 20 feet tall, uses large amounts of water and may crowd out other plant species and affect wildlife.

Dr. Larry Gilbert and his colleagues at the Brackenridge Field Laboratory (BFL) will study wasps that attack the cane under the direction of USDA research entomologists Drs. John Goolsby and Patrick Moran.

The wasps create growths called galls that could stress the plants and reduce their competitive advantage.

"The very basic biology of these wasps and how they interact with the plants is not known," says Gilbert, director of BFL. "We're just beginning to work it out."

Gilbert's team will be researching effective means for mass rearing the wasps and studying basics of the plant-wasp interaction inside a new greenhouse being completed at BFL.

The field lab is home to other biocontrol research—controlling imported fire ants using a small fly—and Gilbert says that experience has prepared the BFL researchers for their work investigating biocontrol of the giant cane, which has also invaded the station property.

The wasps are one of the many aspects of the cane's biology and ecology being studied by the USDA's Goolsby and Moran.


SOURCE : The University of Texas at Austin


Sunday, July 27, 2008

New Satellite Imaging Research Could Save The Lemur In Madagascar



New satellite imaging research may help save the dwindling lemur population in the African nation of Madagascar.

Using satellite imagery, GIS and ecological and demographic data from the field, Robert W. Sussman, Ph.D., professor of anthropology in Arts & Sciences at Washington University in St. Louis, has studied the effects of deforestation on the ringtailed lemur population in Madagascar during the last forty years.


Lemur population in Madascar has declined sharply since the 1950s.
Through education and conservation, a WUSTL expert hopes the trend will one day be reversed.
(Credit: Image courtesy of Washington University in St Louis)


He has determined that while causes of deforestation vary in different parts of the African island nation, the total lemur (lemur catta) population has dropped by more than half since the 1950s. Sussman discussed his long-term field research project in "Habitat Monitoring by GPS in Madagascar" during the "From Global to Local: Impact of Field Research in Biological Anthropology" session Sunday, Feb. 17, at the annual meeting of the American Association for the Advancement of Science in Boston, Mass.

Sussman, who first began studying lemur populations in Madagascar in 1969, continues to conduct and coordinate long-term research of the demography, ecology and social organization of lemurs at the Beza Mahafaly Reserve and in southern Madagascar.

He is co-founder of the reserve, which began as part of a cooperative program in research, conservation, education and development between Washington University in St. Louis, Yale University and the University of Madagascar (currently University of Antananarivo), which also manages the reserve.

In the years since its development in 1978, hundreds of research papers have been written about the flora, fauna and people of Madagascar. Education programs on the local animals and conservation have been developed for the local people. Many non-Malagasy students have completed their doctoral field work in the area, and more than 100 local students have earned graduate degrees based on research done at and around the reserve.

Sussman now uses the reserve as a base for his GIS and satellite imagery studies of southwestern Madagascar — the entire range of the ringtailed lemurs. He is looking at the relationship between deforestation, land use by the human population, and the density and distribution of ringtailed lemurs.

While sifting through satellite data going back to 1950, Sussman and colleagues have determined a measure of "greenness" of the land over time. There is an 80 percent correlation between the level of greenness and the lemur population density, said Sussman. The lemurs congregate in the greener areas, but those areas are also the ones being deforested at the fastest rate.

While it is estimated that the lemur population in Madagascar has dropped to a total of approximately 750,000 from more than 1.5 million in the 1950s, Sussman hopes the trend will one day be reversed.

"Through education and conservation, we can make positive steps," he said. "We must work with the local people to help stop the damaging effects of deforestation, not only to the animal populations, but to the human population as well."


SOURCE : Washington University in St Louis


Antimicrobials Target Pathogens On Fruits And Vegetables



A novel food safety treatment tested by Agricultural Research Service (ARS) scientists could become an asset to the fast-growing fresh-cut produce industry.


Bacteriophages are showing promise as a way to control E. coli on lettuce and fresh cantaloupe.
(Credit: iStockphoto/Zoran Kolundzija)


The antimicrobial treatment involves the use of submicroscopic agents that are unable to reproduce or grow outside bacterial host cells. The purified viral agents are called bacteriophages, which means "bacteria eater," and they can wreak havoc on deadly bacteria, such as E. coli O157:H7, that sicken consumers.

The bacteriophage research is being conducted by microbiologist Manan Sharma, with the ARS Food Safety Laboratory, in Beltsville, Md., in collaboration with researchers at Intralytix, Inc., based in Baltimore, Md.

Interest in bacteriophages is ramping up with the emergence of antibiotic-resistant organisms. These "phages" are present in the environment and only attack bacteria; they do not have an adverse effect on humans and animals.

Sharma tested a group of phages (ECP-100) on refrigerated samples of fresh-cut cantaloupe. The treatments reduced pathogens on the samples of fresh-cut cantaloupe by 100-fold in comparison to untreated samples.

Sharma also tested the phages on refrigerated fresh-cut lettuce. The results indicate that bacteriophage treatments can kill E. coli O157:H7 on the surface of leafy green commodities with the same level of efficiency seen in the fresh-cut cantaloupe.

Phages reproduce by latching onto bacteria. The viral DNA is injected into the bacterial hosts' cells, where it directs the production of progeny phages. These phages kill bacterial host cells on exit, and then move on to infect more bacterial cells.

The trials indicated that the phage treatments could be effective in killing E. coli O157:H7 in produce.


SOURCH : USDA/Agricultural Research Service


Botanists Identify New Species Of North American Bamboo



Two Iowa State University botanists and their colleague at the University of North Carolina have discovered a new species of North American bamboo in the hills of Appalachia. It is the third known native species of the hardy grass. The other two were discovered more than 200 years ago.

ISU botanists Lynn Clark and Jimmy Triplett study bamboo diversity and evolution. They first heard about "hill cane" from University of North Carolina botanist Alan Weakley. As soon as they saw it, they knew it was different.

'Hill cane'

Lynn Clark, Iowa State professor of ecology, evolution and organismal biology, and Ph.D. student Jimmy Triplett study bamboo diversity and evolution. They first heard about "hill cane" from Alan Weakley, a botanist at the University of North Carolina. Although the plant was known to the people in the area, its distinctiveness was not recognized.

Hill cane differs from the other two native North American bamboo species -- commonly known as switch cane and river cane -- in an important way: It drops its leaves in the fall.

"That's why it was recognized locally as being different," Clark said. "It's pretty uncommon for bamboos to drop their leaves."

Clark should know. She's an internationally recognized bamboo expert. She had previously discovered 74 new species of bamboo.

"All the other new ones came from Central and South America," she said. "It's so exciting to find a new species in our own backyard!"

Her 75th species discovery has been named Arundinaria appalachiana. Clark, Triplett and Weakley recently completed the intricate process botanists are obliged to follow to officially name and describe a newfound species. Following rules laid out in the International Code of Botanical Nomenclature, they prepared a short description of the plant in Latin and a longer one in English, and provided drawings and other information to make a strong case for the recognition of A. appalachiana as a distinct species of bamboo. They submitted their evidence in a manuscript to the scientific journal Sida, Contributions to Botany, convincing the peer reviewers that the bamboo they discovered was new. Their study was published last fall.

Bamboos of North America

There are 1,400 known species of bamboo. Of those, about 900 are tropical and 500 are temperate. The bamboos of North America are found in the Eastern and Southeastern United States, from New Jersey south to Florida and west to Texas. River cane (Arundinaria gigantea) occurs in low woods and along riverbanks. Switch cane (Arundinaria tecta) is found in non-alluvial swamps, moist pine barrens, live oak woods and along sandy margins of streams.

"Most people have no idea that we have native bamboo in the U.S.," Clark said. "But it has been a very important plant ecologically. And there's recent interest in using it for re-vegetation projects because it's native and was used for habitat by so many different animals, especially birds."

Building a bamboo family tree

Clark and Triplett began looking at the North American bamboos as part of a larger collaboration with botanists worldwide to develop an evolutionary family tree of bamboo species. They're using modern DNA sequencing technologies together with traditional plant taxonomy, which involves observation and description of a plant's form, anatomy, ecology and other characteristics.

"We want to get the big picture of how all the temperate bamboos are related to each other. That means taking inventory of what exists, then comparing notes," Clark said.

They already know that the closest relatives of native North American bamboos are not in Central or South America, but are in East Asia.

"That's a well-known pattern of diversity in plants and animals. Plants known to be closely related that were previously found across a large area of the earth are only in those two areas now. For various reasons, the Eastern U.S. and East Asia are a repository for a lot of diversity," Clark said.

"But we still don't understand exactly how long it has been since our bamboos separated from their Asiatic cousins. And we don't know how we ended up with three species in North America and 500 in East Asia," she said.

Although botanists had previously studied the North American bamboos, no one had done extensive fieldwork to study and collect the plants in the wild, and questions remained as to whether there was really more than just a single species. In 2003, with funding from the National Geographic Society, Clark and Triplett set off for the Southeast to find the switch cane and river cane in their native habitats.

They knew it was different

"Once we actually saw the plants in the field, we knew quickly that there were two distinct species," Clark said. "But we kept hearing about a third plant, called hill cane."

And as soon as they saw it, they knew it was different.


SOURCE : Iowa State University


Saturday, July 26, 2008

Reclaimed Wastewater Benefits Florida's Citrus Orchards



he Sunshine State has seen rapid growth in population during the last 50 years. The 1997 U.S. Census showed that the population of Florida increased more than five-and-a-half times from 1950 to 2000. Naturally, along with population increases, Florida is experiencing an increase in the amount of municipal waste. Studies confirm that the amount of wastewater generated by cities in Florida has increased more than fivefold since 1950.

Environmental concerns about pollution of surface waters by treated wastewater have caused many communities to consider alternate ways to use secondary-treated, or reclaimed, wastewater. Before 1986, the city of Orlando and Orange County were discharging wastewater into a creek that flows into Lake Tohopekaliga in central Florida. To address concerns that the process would affect the quality water in the lake, city and county officials, along with the U.S. Environmental Protection Agency, devised a plan to use the wastewater for agricultural irrigation.

According to a 2005 report by the Florida Department of Environmental Protection, there are currently 440 "reclaimed water reuse systems" in Florida, irrigating thousands of acres of golf courses, public land, and residential landscapes with 2,385 million liters of reclaimed water per day. Reclaimed wastewater is also being used to irrigate some of Florida's world-renowned citrus orchards. Because yearly rainfall in Florida is seasonal, with 75% of annual rainfall usually occurring between June and September, citrus growers rely on supplemental irrigation for healthy citrus crops.

In a study supported by the City of Orlando and Orange County (FL), researchers set out to determine whether long-term irrigation with treated municipal wastewater reduced citrus tree health, (appearance and leaf nutrient content), decreased fruit loads, impacted fruit quality, or created increases in soil contaminants. Dr. Kelly T. Morgan, a scientist at the University of Florida's, Southwest Florida Research and Education Center, published the study report in the April, 2008 issue of HortScience.

Dr. Morgan explained, "Increased water use by the growing population and localized water shortages during low rainfall years have resulted in the development of water use restrictions and decreases in permitted water use for agriculture. Increased use of reclaimed water for agricultural irrigation would not only reduce the wastewater disposal problem for urban areas, but could also reduce the amount of water withdrawn from Florida's aquifers used for irrigation."

The yearly monitoring project, which began in the 1990s and ended in 2004, concluded that using reclaimed water for irrigation of citrus orchards showed few detrimental effects on the orchards. Morgan commented, "Appearance of trees irrigated with reclaimed water was usually better, with higher canopy, leaf color, and fruit crop ratings than orchards irrigated with groundwater. Although there was higher weed growth in reclaimed water-irrigated orchards due to higher soil water content, growers apparently have made adequate adjustments to their herbicide practices."

Researchers concluded that long-term citrus irrigation with high-quality reclaimed water on well-drained sandy soils did not significantly reduce tree viability or yield and required relatively little adjustment in crop production practices: good news for the environment and citrus producers alike.


SOURCE : American Society for Horticultural Science


New Coral Bleaching Prediction System Calls For Low Level Of Bleaching In Caribbean This Year



A new NOAA coral bleaching prediction system indicates that there will be some bleaching in the Caribbean later this year, but the event will probably not be severe. NOAA issued the first-ever seasonal coral bleaching outlook this week at the 11th International Coral Reef Symposium in Ft. Lauderdale, Fla.


Large colony of bleached Montastrea annularis. (Credit: NOAA)

The system also suggests that there is a risk of widespread bleaching in the Northwestern Hawaiian Islands in August, but little bleaching elsewhere during the northern hemisphere summer.

"The ability to predict coral bleaching events and provide advance warning is critically important to sustaining healthy reefs," said Tim Keeney, deputy assistant secretary of commerce for oceans and atmosphere and co-chair of the United States Coral Reef Task Force. "When coral reef managers and reef users are alerted, they can mobilize monitoring efforts, develop response strategies, and educate reef users and the public on coral bleaching and possible effects on reef resources."

The new prediction system uses NOAA experimental sea surface temperature forecasts to develop maps of anticipated coral bleaching severity during the upcoming bleaching season (August to October). While NOAA's Coral Reef Watch Program uses satellite sea surface temperature data to alert managers and scientists around the world of the risk of coral bleaching, the new prediction system includes longer range temperature forecasts up to three-months.

Coral bleaching is associated with a variety of stresses, especially increased ocean temperatures. This causes the coral to expel symbiotic micro-algae living in their tissues -- algae that provide corals with food. Losing their algae leaves coral tissues devoid of color, and thus they appear bleached. Prolonged coral bleaching of over a week can lead to coral death and the loss of coral reef habitats for a range of marine life.

A major coral bleaching event occurred in the Caribbean in 2005, resulting in significant coral death in much of the region.

"As global temperatures continue to climb, predicting coral bleaching becomes even more critical," said C. Mark Eakin, Ph.D., coordinator of NOAA's Coral Reef Watch Program. "Our goal is to issue bleaching forecasts for coral reefs worldwide."

The new system was developed by scientists of NOAA's Coral Reef Watch in Silver Spring, Md. and NOAA's Earth Science Research Laboratory in Boulder, Colo., with funding from the NOAA Climate Program Office's Sectoral Applications Research Program and NOAA's Coral Reef Conservation Program.


SOURCE : National Oceanic And Atmospheric Administration


'Snapshots' Of Eyes Could Serve As Early Warning Of Diabetes



A new vision screening device, already shown to give an early warning of eye disease, could give doctors and patients a head start on treating diabetes and its vision complications, a new study shows.

The instrument, invented by two scientists at the University of Michigan Kellogg Eye Center, captures images of the eye to detect metabolic stress and tissue damage that occur before the first symptoms of disease are evident.

For people with diabetes -- diagnosed or not -- the new device could offer potentially significant advantages over blood glucose testing, the "gold standard" for diabetes detection.

The device takes a specialized photograph of the eye and is non-invasive, taking about five minutes to test both eyes.

In the July issue of Archives of Ophthalmology, Victor M. Elner, M.D., Ph.D., and Howard R. Petty, Ph.D., report on the potential of the new instrument to screen for diabetes and determine its severity. If further testing confirms the results to date, the new instrument may be useful for screening people who are at risk of diabetes but haven't been diagnosed.

"Our objective in performing this study was to determine whether we could detect abnormal metabolism in the retina of patients who might otherwise remain undiagnosed based on clinical examination alone," says Elner, professor, Department of Ophthalmology and Visual Sciences at U-M Medical School.

Metabolic stress, and therefore disease, can be detected by measuring the intensity of cellular fluorescence in retinal tissue. In a previous study, Petty and Elner reported that high levels of flavoprotein autofluorescence (FA) act as a reliable indicator of eye disease.

In their new study, Elner and Petty measured the FA levels of 21 individuals who had diabetes and compared the results to age-matched healthy controls. The Kellogg scientists found that FA activity was significantly higher for those with diabetes, regardless of severity, compared to those who did not have the disease. The results were not affected by disease severity or duration and were elevated for diabetics in each age group: 30 to 39 years, 40 to 49 years, and 50 to 59 years.

Given the increasing prevalence of diabetes, the FA device holds the potential to help address a leading and growing public health concern.

Some 24 million Americans have diabetes and an additional 57 million individuals have abnormal blood sugar levels that qualify as pre-diabetes, according to the latest report from the Centers for Disease Control and Prevention. In addition, 4.1 million people over the age of 40 suffer from diabetic retinopathy, an eye-related complication of diabetes that is the leading cause of blindness among working-age adults.

Twelve individuals in the study were known to have diabetic retinopathy, a disease in which blood vessels in the eye are damaged. The individuals with diabetic retinopathy in at least one eye had significantly greater FA activity than people with diabetes who do not have any visible eye disease.

"The abnormal readings indicated that it may be possible to use this method to monitor the severity of the disease," says Elner.

Petty, a biophysicist and imaging expert, explains that hyperglycemia -- or high blood sugar -- is known to induce cell death in diabetic tissue soon after the onset of disease but before symptoms can be detected clinically.

"Increased FA activity is the earliest indicator that cell death has occurred and tissue is beginning to break down," says Petty, professor of Ophthalmology and Visual Sciences, and professor of Microbiology and Immunology at the U-M Medical School. "FA serves as a 'spectral-biomarker' for metabolism gone awry, and we can use the results to detect and monitor disease."

Petty also observes that unlike glucose monitoring, elevation of FA levels reflects ongoing tissue damage. That knowledge, he says, could motivate patients to intensify their efforts to manage the disease.

The Michigan researchers also note that elevated FA does not always mean that an individual has diabetes. "Because of the prevalence of diabetes in our population, individuals with abnormally high FA would be prompted to undergo glucose tolerance testing," says Elner. "If the findings were negative for diabetes, we would look for other causes of ocular tissue dysfunction."

Both Elner and Petty agree that the device has great potential as a tool for diabetes screening and management. "So much damage occurs before the disease can be detected by a doctor," says Elner. "Early diagnosis will allow us to reduce organ damage and prevent many complications that accompany this disease."

Elner and Petty have filed for patents and have formed a company, OcuSciences, Inc., to commercialize the metabolic imaging instrument.


SOURCE : University of Michigan Health System


Friday, July 25, 2008

Bees Go 'Off-color' When They Are Sickly



Bumble-bees go 'off colour' and can't remember which flowers have the most nectar when they are feeling under the weather, a new study from the University of Leicester reveals.

The behaviour of the bumbling bees reveals that, like humans who are ill, bees are often not at their most astute and clever when they feel poorly.

Lecturer in Animal Biology at the University of Leicester Dr. Eamonn Mallon, who lead the research group, said: "Disease can influence different behaviours including foraging, mate choice, and predator avoidance. Several recent papers have shown reduced learning abilities in infected insects. However, it is difficult to separate the effects of the immune response from the direct effects of the parasite. That was the purpose of our study"

Bees were divided into a control group and a group that were injected with lipopolysaccharide, a substance that stimulated an immune response without a need for the bee to be infected with a disease. Bees were offered the choice of blue and yellow artificial flowers only one type of which contained sugar water. An individual's flight was recorded over ninety visits to these flowers. Eventually the bees spent almost all of their time going to the rewarding flowers, but it took the immune stimulated bees longer to reach this point.

Dr Mallon added: "This work has two important applications. Firstly, there is a lot of interest in the connections between the immune system and the nervous system in human biology. The Mallon lab was the first to show that these interactions also exist in the much more experimentally tractable insects.

"Secondly, there is concern about both the decline in wild bumble-bee species and the effects of disease on the honeybee industry. It has been shown that learning is vitally important to how well a colony prospers. This effect of immunity on learning highlights a previously unconsidered effect of disease on colony success."

Future work will look at the basis of this neuro-immune interaction. Is it due to the immune system using up some resource required to form memories or is it due to the damaging effects of the immune response on the nervous system?

The research was conducted in the Department of Biology, in collaboration with the Department of Genetics, at the University of Leicester. The Leicester team consisted of A. Alghamdi, L. Dalton, A. Phillis, E. Rosato and E. B. Mallon


SOURCE : University of Leicester


Mysterious Mountain Dinosaur May Be New Species



A partial dinosaur skeleton unearthed in 1971 from a remote British Columbia site is the first ever found in Canadian mountains and may represent a new species, according to a recent examination by a University of Alberta researcher.

This composite shows what bones were found
and what the Sustut dinosaur may have looked like 70 million years ago.
(Credit: University of Alberta, Edmonton, Canada)



Discovered by a geologist in the Sustut Basin of north-central British Columbia 37 years ago, the bones, which are about 70 million years old, were tucked away until being donated to Dalhousie University in 2004 and assigned to then-undergraduate student Victoria Arbour to research as an honours project. She soon realized that the bones were a rare find: they are very well-preserved and are the most complete dinosaur specimen found in B.C. to date. They are also the first bones found in B.C.'s Skeena mountain range.

"There are similarities with two other kinds of dinosaurs, although there's also an arm bone we've never seen before. The Sustut dinosaur may be a new species, but we won't know for sure until more fossils can be found," said Arbour, who finished researching the bones while studying for her master's degree at the University of Alberta. "It's very distinct from other dinosaurs that were found at the same time in southern Alberta."

The seven shin, arm, toe and possible skull bones were found nestled in a dip between mountains in the Skeena range, and while the fragments resemble those from a small two-legged, plant-eating dinosaur, the rest of the creature's identity is a mystery, Arbour says.

The fossils are currently in the collection of the Royal British Columbia Museum in Victoria and Arbour hopes to lead a U of A team to the site for future investigation.

Arbour's findings were published recently in the Canadian Journal of Earth Sciences. The research was funded by NSERC and Alberta Ingenuity.


SOURCE : University of Alberta


More People Are Getting Sick From Eating Fresh Fruits



St. Paul, MN (January 27, 2003) -- Salmonella, E. coli, shigellosis, hepatitis A, and Norwalk -- these food-borne diseases can produce symptoms that run from the mild to life-threatening. The young and old are particularly vulnerable and while consumption of beef and poultry have been the most common sources of such infections, fresh fruits and vegetables are being increasingly implicated in such outbreaks. So much so, that plant disease scientists are now taking a closer look at this issue.

"Historically, human pathogens like E. coli and Salmonella have rarely been associated with plants, so plant disease scientists have not looked at them directly," says J.W. Buck, a plant pathologist at the University of Georgia. But that is changing, says Buck, as such incidences continue to increase.

Buck says there is no single reason why the number of reported produce-related outbreaks in the U.S. per year doubled between 1973-1987 and 1988-1992 and why they continue to rise. Possible explanations include the simple fact that we are eating more fruits and vegetables than ever before. But experts agree that there is more to it than that and that our food production practices likely bear some responsibility.

But identifying the exact point along the way, from field to grocery store, where a strawberry or head of lettuce, for example, might have become contaminated can be difficult, if not impossible. Unlike other commodities such as beef and chicken, which are rigorously inspected, methods to detect pathogens on fresh produce are less advanced and the sporadic nature of most contamination further limits the effectiveness of testing.

"Plant disease scientists know a lot about how other microorganisms interact with plants and the environment to create an outbreak," says Buck. "This same knowledge can be applied to human pathogens as well. An exchange of research tools and experiences between plant pathologists and food microbiologists could result in tremendous advances towards managing food-borne diseases related to produce consumption."

According to Buck, one impediment to this kind of research, however, is that plant pathology laboratories currently lack the appropriate facilities for working with human pathogens, which are considered biosafety hazards. Until such changes can be made, says Buck, plant pathology models and practices, such as integrated pest management, that have worked well in controlling other plant diseases would likely work in helping to minimize the risk of human disease as well. Says Buck, "No doubt plant disease scientists can, and should, play a more significant role in food safety issues in the future."

The microbiological safety of fruits and vegetables is the subject of this month's APS feature story and can be found at APS website at: http://www.apsnet.org . The American Phytopathological Society (APS) is a non-profit, professional scientific organization dedicated to the study and control of plant disease with 5,000 members worldwide.


SOURCE : American Phytopathological Society


Thursday, July 24, 2008

Spinal Cord Stem Cells Could Be Basis Of Nonsurgical Treatment For Spinal-cord Injuries



A researcher at MIT's Picower Institute for Learning and Memory has pinpointed stem cells within the spinal cord that, if persuaded to differentiate into more healing cells and fewer scarring cells following an injury, may lead to a new, non-surgical treatment for debilitating spinal-cord injuries.

The work is by Konstantinos Meletis, a postdoctoral fellow at the Picower Institute, and colleagues at the Karolinska Institute in Sweden. Their results could lead to drugs that might restore some degree of mobility to the 30,000 people worldwide afflicted each year with spinal-cord injuries.


Coronal sections of injured adult spinal cord, anterior to posterior.
The labeling shows recombined ependymal cells and their progeny (white)
migrating out to the injury area in the dorsal funiculus,
as a response to the injury (injury is in the image on the right hand corner).
(Credit: Image / Konstantinos Meletis)


In a developing embryo, stem cells differentiate into all the specialized tissues of the body. In adults, stem cells act as a repair system, replenishing specialized cells, but also maintaining the normal turnover of regenerative organs such as blood, skin or intestinal tissues.

The tiny number of stem cells in the adult spinal cord proliferate slowly or rarely, and fail to promote regeneration on their own. But recent experiments show that these same cells, grown in the lab and returned to the injury site, can restore some function in paralyzed rodents and primates.

The researchers at MIT and the Karolinska Institute found that neural stem cells in the adult spinal cord are limited to a layer of cube- or column-shaped, cilia-covered cells called ependymal cells. These cells make up the thin membrane lining the inner-brain ventricles and the connecting central column of the spinal cord.

"We have been able to genetically mark this neural stem cell population and then follow their behavior," Meletis said. "We find that these cells proliferate upon spinal cord injury, migrate toward the injury site and differentiate over several months."

The study uncovers the molecular mechanism underlying the tantalizing results of the rodent and primate and goes one step further: By identifying for the first time where this subpopulation of cells is found, they pave a path toward manipulating them with drugs to boost their inborn ability to repair damaged nerve cells.

"The ependymal cells' ability to turn into several different cell types upon injury makes them very interesting from an intervention aspect: Imagine if we could regulate the behavior of this stem cell population to repair damaged nerve cells," Meletis said.

Upon injury, ependymal cells proliferate and migrate to the injured area, producing a mass of scar-forming cells, plus fewer cells called oligodendrocytes. The oligodendrocytes restore the myelin, or coating, on nerve cells' long, slender, electrical impulse-carrying projections called axons. Myelin is like the layer of plastic insulation on an electrical wire; without it, nerve cells don't function properly.

"The limited functional recovery typically associated with central nervous system injuries is in part due to the failure of severed axons to regrow and reconnect with their target cells in the peripheral nervous system that extends to our arms, hands, legs and feet," Meletis said. "The function of axons that remain intact after injury in humans is often compromised without insulating sheaths of myelin."

If scientists could genetically manipulate ependymal cells to produce more myelin and less scar tissue after a spinal cord injury, they could potentially avoid or reverse many of the debilitating effects of this type of injury, the researchers said.

This study was supported by grants from the Swedish Research Council, the Swedish Cancer Society, the Foundation for Strategic Research, the Karolinska Institute, EuroStemCell and the Christopher and Dana Reeve Foundation.


SOURCE : Massachusetts Institute of Technology


Brain Morphology Of Homo Liujiang Cranium Fossil Detailed With 3-D CT Scan



High-resolution industrial computed tomography was used to scan the Homo Liujiang cranium fossil, and the three-dimensional virtual brain image was reconstructed. More information for the phyletic evaluation of the Homo Liujiang was derived from this new research.

Hominin fossils are the most important materials to explore human origins and evolution. Since most hominin fossils are incomplete, or filled with a heavy calcified matrix, it is difficult or often impossible to reconstruct the endocast in a real fossil without destroying it. Accordingly, traditional methods limited the study of human brain evolution.

CT can explore fossils in a noninvasive way by transforming a real fossil into a virtual object, and make it possible for paleoanthropologists to extend the study of fossil specimens from the exterior to the interior. Using high-resolution industrial CT, the Homo Liujiang brain image was reconstructed.

The Liujiang cranium is the most complete and well-preserved late Pleistocene human fossils ever unearthed in South China. Because the endocranial cavity is filled with hard stone matrix, earlier studies focused only on the exterior morphology of the specimen using the traditional methods. Arguments about the phyletic evaluation of the Liujiang hominin fossil have existed for a long time.

The new research was led by Wu Xiujie from Institute of Vertebrate Paleontology and Paleoanthropology (IVPP).

In this study, the authors used high-resolution industrial CT to scan the Liujiang cranium, and reconstruct the three-dimensional (3-D) brain image. Compared with the endocasts of the hominin fossils and modern Chinese, most morphological features of the Liujiang brain are in common with modern humans, including a round brain shape, bulged and wide frontal lobes, an enlarged brain height, a full orbital margin and long parietal lobes.

There are a few differences between Liujiang and the modern Chinese in our sample, including a strong posterior projection of the occipital lobes, and a reduced cerebellar lobe. The measurement of the virtual endocast shows that the endocranial capacity of Liujiang is 1567 cc, which is in the range of Late Homo sapiens and much beyond the mean of modern humans. The brain morphology of Liujiang is assigned to Late Homo sapiens.

IVPP is the only special institute mainly dealing with the research of origin and evolutionary history of hominin fossils. In the past 80 years, a few complete hominin crania fossila were found in China. "With CT scanning and 3D visualization techniques to reconstruct virtual specimens, it is now possible for Chinese hominin paleontologists to conduct paleoneurological studies of our national treasures", said Dr. Wu Xiujie.

The study is supported by the National Natural Science Foundation of China.


SOURCE : Science in China Press