September 14, 2009, 11:55 PM CT

For carnivorous plants, slow but steady wins the race

Like the man-eating plant in Little Shop of Horrors, carnivorous plants rely on animal prey for sustenance. Fortunately for humans, carnivorous plants found in nature are not dependent on a diet of human blood but rather are satisfied with the occasional fly or other insect. The existence of carnivorous plants has fascinated botanists and non-botanists alike for centuries and raises the question, "Why are some plants carnivorous?" .

A recent article by Drs. Jim Karagatzides and Aaron Ellison in the recent issue of the American Journal of Botany (www.amjbot.org/cgi/content/full/96/9/1612) addresses this question. As Ellison stated, "The general answer to this is that in environments that have few nutrients (such as bogs, where we study carnivorous plants), carnivory allows these plants to capture nutrients 'on the wing'. But if it's so good to be a carnivorous plant in these kinds of environments, why aren't there more carnivorous plants? Knowing how much it 'costs' a carnivorous plant to make a trap is a key piece of information needed to understand why there aren't more carnivorous plants".

Elllison and Karagatzides simultaneously measured both costs and benefits for traps, leaves, roots, and rhizomes of 15 different carnivorous plant species, including pitcher plants and the Venus fly trap. By measuring the construction cost of carbon needed to create these plant structures and comparing it to the payback timethe amount of time the structure takes to photosynthesize to recoup the carbon used in its constructionEllison and Karagatzides were able to determine how beneficial a trap might be to a plant......... Posted by: Erica      Read more         Source

September 11, 2009, 7:46 AM CT

Dividing cells 'feel' their way out of warp

Every moment, millions of a body's cells flawlessly divvy up their genes and pinch perfectly in half to form two identical progeny for the replenishment of tissues and organs even as they collide, get stuck, and squeeze through infinitesimally small spaces that distort their shapes.

Now Johns Hopkins scientists, working with the simplest of organisms, have discovered the molecular sensor that lets cells not only "feel" changes to their neat shapes, but also to remodel themselves back into ready-to-split symmetry. As per a research findings published September 15 in Current Biology, the scientists show that two force-sensitive proteins accumulate at the sites of cell-shape disturbances and cooperate first to sense the changes and then to resculpt the cells. The proteins myosin II and cortexillin I monitor and correct shape changes in order to ensure smooth division.

"What we found is an exquisitely tuned mechanosensory system that keeps the cells shipshape so they can divide properly," says Douglas N. Robinson, Ph.D., an associate professor of Cell Biology, Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine.

Faulty cell division can put organisms, including people, on the pathway to diseases such as cancer, Robinson notes, and a better understanding of how cells respond to mechanical stress on their shapes could present new targets for both diagnosing and treating such diseases......... Posted by: Janet      Read more         Source

September 11, 2009, 7:38 AM CT

Oil and wildlife don't mix in Ecuador's Eden

What harm can a simple road do in a pristine place such as Ecuador's Yasuni National Park, home to peccaries, tapirs, monkeys and myriad other wildlife species? A great deal, it turns out. Specifically, it can turn subsistence communities into commercial hunting camps that empty rainforests of their wildlife, scientists from the Wildlife Conservation Society and the IDEAS-Universidad San Francisco de Quito in Ecuador have found.

A study by WCS field researchers in the park observed that the presence of a single road in a protected area and the subsidies provided by oil companies to local people can fundamentally change how indigenous communities use their resources by providing both access to deeper parts of the forest and a cheap means of getting meat to nearby wildlife markets.

The study appears in the most recent issue of the journal Animal Conservation

"We've observed that a road in a forest can bring huge social changes to local groups and the ways in which they utilize wildlife resources," said WCS and USFQ researcher Esteban Surez, main author of the study. "Communities existing inside and around the park are changing their customs to a lifestyle of commercial hunting, the first stage in a potential overexploitation of wildlife".

" A simple, seemingly inoffensive road can have far-reaching effects on a landscape and its people," said Dr. Avecita Chicchn, Director of WCS's Latin America and Caribbean Program. "It provides hunters with more access to a wider range of forest while providing a low-cost transportation route to markets. More importantly, it plugs communities more easily into the larger economic world while creating increased demand for numerous species of animals. It is the road to unsustainability."........ Posted by: Kelly      Read more         Source

September 11, 2009, 7:33 AM CT

As ash borer claims more trees

Mark Widrlechner may someday be known as the modern-day Johnny Appleseed for ash trees.

As the devastating insect emerald ash borer is working its way across North America destroying almost all the native ash trees it encounters, Widrlechner is rapidly collecting and storing ash tree seeds.

Like the legendary Appleseed who planted apple trees across the country, Widrlechner's seed stocks can serve as a national source for reintroducing ash trees once the devastation can be controlled.

Widrlechner, horticulturist for the United States Department of Agriculture's Agricultural Research Service (ARS) and assistant professor of agronomy and horticulture at ISU, is a curator at the North Central Regional Plant Introduction Station in Ames, Iowa, responsible for collecting and maintaining seeds for several species of trees, including ash, for the USDA's National Plant Germplasm System.

As the pest devours ash tree populations on its way across North America, there may soon be few, if any, ash trees left.

"Where these borers have been present the longest, it has basically been a total wipeout," said Widrlechner.

"That is something we rarely see in nature," he said. "It's uncommon for a pest to come in and just clean something out. It doesn't just attack sick trees. Emerald ash borer attacks healthy trees. It attacks small trees. So you don't have just big, old trees falling to this, you've got 2 to 3 inch saplings falling to this."........ Posted by: Erica      Read more         Source

September 11, 2009, 6:55 AM CT

Migrating birds chill to fatten up

Marathon runners are famed for pasta packing in the days before a big run but when tiny passerine birds set out on their epic migrations, the distances are too great to cover on the energy reserves with which they embark. Michał Wojciechowski and Berry Pinshow explain that most birds stop off en route to their destination to refuel. One of the Eurasian blackcaps' preferred refuelling stops is Midreshet Ben-Gurion, Israel, where the birds fill up on fruit and insects before setting off again. Knowing that birds expend twice as much energy during stopovers than they use in transit, the duo wondered whether the tiny aviators drop their body temperature at night during stopovers to save energy and build up their reserves faster. They publish this discovery on 11 September 2009 in The Journal of Experimental Biology at http://jeb.biologists.org.

Collecting migrating blackcaps at their stopover site on the Sede Boqer Campus of Ben-Gurion University and near Toron, Poland, Wojciechowski and Pinshow weighed the birds and monitored their body temperatures and metabolic rates as the birds stocked up on fruit supplemented with mealworms. During the day the birds' body temperatures hovered around 42.5C, but as dusk fell, their temperatures began to drop. The average normal body temperature at night was about 38.8C, while one especially skinny individual's temperature plummeted to 33C. And when the team plotted the birds' body masses against their nocturnal temperatures, the smaller birds' (< 16.3g) temperatures correlated with their body masses......... Posted by: Kelly      Read more         Source

September 10, 2009, 7:12 AM CT

River flow and temperature limit trout numbers

Over a 23-year study, Javier Lobn-Cervi has found the mechanism that controls the number of salmonids found each year in Cantabrian rivers. His method has been to monitor population numbers in relation to river flow in March, when the juvenile fish emerge. He concludes that environmental conditions change each year and modify river flow, positively or negatively affecting survival rates. This information throws light on a long debate within ecological theory about the mechanisms that regulate the size of animal populations.

In 2000, populations of trout (Salmo trutta) in the rivers of north East Spain suffered an alarming decline, but fishing was never banned, and fish numbers fell still further. However, these populations recovered "naturally" within a very short time period. Javier Lobn-Cervi, main author of the research study and a researcher at the National Museum of Natural Sciences (CSIC) has the answer, and has published it in the journal Freshwater Biology

"If we use a small measurement and calculate the amount of water that was flowing in March (when the fish eggs emerge), we can predict how a number of trout there will be now, how a number of there will be in two years, how a number of should be fished, how a number of females are going to reproduce in other words, we can monitor the entire population perfectly", the researcher tells SINC......... Posted by: Kelly      Read more         Source

September 10, 2009, 7:06 AM CT

Getting plants to rid themselves of pesticide residues

Researchers in China are reporting the "intriguing" discovery that a natural plant hormone, applied to crops, can help plants eliminate residues of certain pesticides. The study is scheduled for the Sept. 23 issue of ACS' Journal of Agricultural and Food Chemistry, a bi-weekly publication.

Jing Quan Yu and his colleagues note that pesticides are essential for sustaining food production for the world's growing population. Farmers worldwide use about 2.5 million tons of pesticides each year. Researchers have been seeking new ways of minimizing pesticide residues that remain in food crops after harvest with little success. Prior research suggested that plant hormones called brassinosteroids (BRs) might be an answer to the problem.

The researchers treated cucumber plants with one type of BR then treated the plants with various pesticides, including chloropyrifos (CPF), a broad-spectrum commercial insecticide. BR significantly reduced their toxicity and residues in the plants, they say. BRs appears to be "promising, environmentally friendly, natural substances suitable for wide application to reduce the risks of human and environmental exposure to pesticides," the researchers note. The substances do not appear to be harmful to people or other animals, they add......... Posted by: Erica      Read more         Source

September 10, 2009, 6:58 AM CT

MicroRNAs to Track Evolutionary History for First Time

The large group of segmented worms known as annelids, which includes earthworms, leeches and bristle worms, evolved millions of years ago and can be found in every corner of the world. Eventhough annelids are one of the most abundant animal groups on the planet, researchers have struggled to understand how the different species of this biologically diverse group relate to each other in terms of their evolutionary history. Now a team of researchers from Yale University and Dartmouth College has used a groundbreaking method to untangle some of that history.

The scientists used a novel source of data-the presence and absence of different microRNA genes-to investigate the evolutionary relationships of annelids. MicroRNAs are small, non-coding genes that have long been known to play an important role in developmental biology but which have never before been used to study the evolutionary relationships between organisms. The team's findings appear online September 9 in the journal Proceedings of the Royal Society B.

"These genes are excellent evolutionary markers," said main author Erik Sperling, a graduate student in Yale's Department of Geology and Geophysics. "Once a microRNA gene is fixed in a species, it is very rarely lost. As such, organisms with similar microRNAs are closely correlation to one another"......... Posted by: Kelly      Read more         Source

September 10, 2009, 6:56 AM CT

Model backs green tea and lemon claim

An animal study at Purdue University has shown that adding ascorbic acid and sugar to green tea can help the body absorb helpful compounds and also demonstrates the effectiveness of a model that could reduce the number of animals needed for these types of studies.

Mario Ferruzzi, associate professor of food science and nutrition, adapted a digestion model with human intestinal cells to show that adding ascorbic acid to green tea would increase the absorbability of catechins found in the tea. Catechins, a class of polyphenols common in tea, cocoa and grape, are antioxidants thought to fight heart disease, stroke, cancer, diabetes and other health problems.

Ferruzzi, Elsa Janle, a Purdue associate research professor of foods and nutrition, and Catrina Peters, a Purdue graduate student in nutrition, were able to demonstrate that adding ascorbic acid, sucrose or both together increases by as much as three times the amount of catechins that can be absorbed into the bloodstream. The results of the in vivo study compared well with those predicted by the in vitro model.

"This model appears to be used as a pre-emptive screening tool at very little cost before you do expensive tests on animals or humans," said Ferruzzi, whose findings were reported in the early online edition of the journal Food Research International. "If you want to get human screening off the ground, it takes months. If you want to use this model, it takes hours"......... Posted by: Kelly      Read more         Source

September 10, 2009, 6:54 AM CT

Individual cells isolated from the biological clock

Alexis Webb enters a small room at Washington University in St. Louis with walls, floor and ceiling painted dark green, shuts the door, turns off the lights and bends over a microscope in a black box draped with black cloth. Through the microscope, she can see a single nerve cell on a glass cover slip glowing dimly.

The glow tells her the isolated nerve cell is busy keeping time.

Webb, a graduate fellow in the Neuroscience Ph.D. Program, working with Erik Herzog, Ph.D., associate professor of biology in Arts & Sciences; Nikhil Angelo, an undergraduate biology major; and James Huettner, Ph.D., associate professor of cell biology and physiology in the School of Medicine, has demonstrated that individual cells isolated from the biological clock can keep daily time all by themselves.

However, by themselves, they are unreliable. The neurons get out of synch and capriciously quit or start oscillating again.

The biological clock, a one-square millimeter area of the brain called the suprachiasmic nucleus, or SCN, just above the roof of the mouth and atop the crossing of the optic nerves, comprises about 20,000 neurons.

These cells, remarkably, contain the machinery to generate daily, or circadian, rhythms in gene expression and electrical activity. But the individual cells are sloppy and must communicate with one another to establish a coherent 24-hour rhythm, says Herzog......... Posted by: Janet      Read more         Source