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

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