July 12, 2007, 10:45 PM CT

How plants learned to respond to changing environments

A team of John Innes centre researchers lead by Professor Nick Harberd have discovered how plants evolved the ability to adapt to changes in climate and environment. Plants adapt their growth, including key steps in their life cycle such as germination and flowering, to take advantage of environmental conditions. They can also repress growth when their environment is not favourable. This involves a number of complex signalling pathways which are integrated by the plant growth hormone gibberellin.

Publishing in the journal Current Biology, the scientists looked at how plants evolved this ability by looking at the genes involved in the gibberellin signalling pathway in a wide range of plants. They discovered that it was not until the flowering plants evolved 300 million years ago that plants gained the ability to repress growth in response to environmental cues.

All land plants evolved from an aquatic ancestor, and it was after colonisation of the land that the gibberellin mechanism evolved. The earliest land plants to evolve were the bryophyte group, which includes liverworts, hornworts and ancestral mosses, a number of of which still exist today. The ancestral mosses have their own copies of the genes, but the proteins they make do not interact with each other and cant repress growth. However, the moss proteins work the same as their more recently evolved counterparts when transferred into modern flowering plants......... Posted by: Beverly      Read more         Source

Thu, 12 Jul 2007 05:14:30 GMT

Rhinanthus minor

I'm still out in the field, but summer student Raakel Toppila has helped out by writing today's entry. – Daniel

Thank you to Stephen, aka stephenbuchan@Flickr from Edinburgh, Scotland for sharing today's image (original via BPotD Flickr Group Pool).

Rhinanthus minor, also known as yellow-rattle, occurs throughout the northern hemisphere, from Europe to Asia to North America. It is a hemiparasitic plant (much like mistletoe), obtaining some nutrients from a host plant or host plants, while still photosynthesizing. This contrasts with holoparasitic plants which lack chlorophyll entirely and therefore have no photosynthesizing apparatus. One study found haustorial connections (morphologically modified tissue which physically penetrates the host plant's vascular tissue) in the roots of an individual Rhinanthus plant connecting to seven different host species. A rather greedy plant! Posted by: Daniel Mosquin      Read more     Source

July 5, 2007, 9:37 PM CT

Chickens And Earth's Magnetic Field

40 years ago, Prof. Dr. Wolfgang Wiltschko was the first to prove that migrating robins use the Earths magnetic field to direct themselves during migration. Their magnetic sensor showed them the course of the field lines of the Earths magnetic field. This produces an inclination compass that reacts to the inclination of the Earths magnetic field to the surface of the Earth, thus distinguishing between pole-wards (the side on which the field lines incline downwards) and equator-wards (the side on which they incline upwards). The inbuilt compass is additionally finely tuned to the field strength of the Earths local magnetic field, but can also be flexibly adapted to other field strengths that the birds encounter in the course of migration. Since that time a compass of this kind has been found in more than 20 species of birds, the majority of them being those songbirds that undertake annual migration. An international working group under the direction of Wolfgang und Roswitha Wiltschko of Frankfurt University has now succeeded in demonstrating the presence of a magnetic sense of direction in domestic chickens as well.

For this purpose, newly hatched chicks were imprinted on a red ball which they from then on regarded as their mother. The researchers then hid the ball behind one of four screens, and taught the chickens by intensive training that the mother was always behind the screen that was in the northerly direction. To demonstrate that the chicken senses this compass point by means of its magnetic sense of direction, the researchers set up an artificial magnetic field in an easterly direction and the chickens did actually seek their mother behind the screen that lay to the east......... Posted by: Beverly      Read more         Source

July 5, 2007, 9:16 PM CT

Exercise in Elderly Improve Quality of Life

A new study appearing in the Journal of the American Geriatrics Society compares the efficacy of three programs designed for reducing falls and improving quality-of-life among the elderly; education, home safety assessment and modification (HSAM) and exercise training. The study also examines the secondary effects of these programs on functional balance, daily activity, fear of falling and depression level, finding that exercise training yields the most significant improvements.

Participation in the study was open to people aged 65 years and older who had required medical attention for a fall within the previous four weeks. Participants were assigned to one of the three fall prevention program groups, and quality of life was then assessed according to the World Health Organization's Quality of Life guidelines, focusing on four domains; physical capacity, psychological well-being, social relationships and environment.

Although all programs appeared to lead to some improvement in quality of life, improvements were significantly greater in the exercise training group. Exercise training participation also led to improvements in functional reach, balance and fear of falling.

"The quality of life benefits reflect not just health states, but also how patients perceive and value the health- and non-health-related aspects of their conditions before and after receiving an intervention," says Dr. Mau-Roung Lin, co-author of the study. These measures may therefore be beneficial for selecting interventions that are of optimal value to older people......... Posted by: Beverly      Read more         Source

July 19, 2007, 10:21 PM CT

Classic beauty and remarkable strength

While the shiny material of pearls and abalone shells has long been prized for its iridescence and aesthetic value in jewelry and decorations, scientists admire mother-of-pearl for other physical properties as well.

Also called nacre ("NAY-ker"), mother-of-pearl is 3,000 times more fracture-resistant than the mineral it is made of, aragonite, says Pupa Gilbert, a physicist at the University of Wisconsin-Madison. "You can go over it with a truck and not break it - you will crumble the outside [of the shell] but not the [nacre] inside. And we don't understand how it forms - that's why it's so fun to study".

Understanding the mechanism by which nacre forms would be the first step toward harnessing its strength and simplicity, she says. "We don't know how to synthesize materials that are better than the sum of their parts".

Writing in the June 29 issue of Physical Review Letters, Gilbert and her colleagues in the UW-Madison department of physics and School of Veterinary Medicine, the Institute for the Physics of Complex Matter in Switzerland and the UW-Madison Synchrotron Radiation Center, now describe unexpected elements of nacre architecture that may underlie its strength and offer clues into how this remarkable material forms.

Like our bones and teeth, nacre is a biomineral, a combination of organic molecules - made by living organisms - and mineral components that organisms ingest or collect from their environment. The aragonite mineral in nacre is made of calcium carbonate, which marine animals form from elements abundant in seawater......... Posted by: Beverly      Read more         Source

July 2, 2007, 9:18 AM CT

Global warming will cause more deaths in summer

Global warming will cause more deaths in summer because of higher temperatures but these will not be offset by fewer deaths in milder winters finds an analysis published online ahead of print in Occupational and Environment Medicine.

The Harvard scientists analysed city-specific weather data correlation to the deaths of more than 6.5 million people in 50 US cities between 1989 and 2000.

They observed that during two-day cold snaps there was a 1.59% increase in deaths because of the extreme temperatures. However, during similar periods of extremely hot weather death rates went up by 5.74%. Deaths did not rise as steeply when temperature fluctuations were less extreme.

Deaths from all causes are known to rise when temperatures go up, and heart attacks and cardiac arrests are more likely when it is very cold. It was anticipated that global warming would increase deaths during hot temperatures but that this would be compensated for by fewer deaths in the winter.

But the authors conclude: Our findings suggest that decreases in cold weather as a result of global warming are unlikely to result in decreases in cold-related mortality in the US. Heat-related mortality, in contrast, may increase, especially if global warming is linked to increased variance of summer temperature......... Posted by: Beverly      Read more         Source

June 15, 2007, 12:43 AM CT

Proteins Sweep up Nanoparticles

Here's a pollution-control tip from nature: Deep inside a flooded mine in Wisconsin, scientists from several institutions including the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have discovered a world in which bacteria emit proteins that sweep up metal nanoparticles into immobile clumps. Their finding may lead to innovative ways to remediate subsurface metal toxins.

The research, which appears in the June 15, 2007 issue of the journal Science, reveals that the proteins travel far from the microbes that produce them, and then amass metal nanoparticles into piles that are too large to be swept away by underground currents. Precisely how and why the bacteria undertake this bit of housecleaning remains a mystery, but it suggests that proteins could play a key role in bioremediation strategies designed to trap harmful metals such as arsenic, lead, uranium, and plutonium.

"We have found, in the environment, that cells release proteins and polypeptides which promote the aggregation of nanoparticulate metals," says John Moreau, lead author of the study and a former PhD student in UC Berkeley's Department of Earth and Planetary Sciences. "The intriguing discovery that biomolecules may shape nanoparticles into larger aggregates, which reduces the nanoparticles' mobility, could have significant implications for bioremediation"......... Posted by: Beverly      Read more         Source

June 12, 2007, 5:01 AM CT

Impact Of Sleep Loss On Attention

The brain responses of those children who don't get enough sleep can accurately predict the impact sleep loss has on their ability to pay attention during the course of a day, as per a research abstract that will be presented Tuesday at SLEEP 2007, the 21st Annual Meeting of the Associated Professional Sleep Societies (APSS).

Brian Millis, of the University of Louisville, combined behavioral and P300 waveform information (a component of the human brain wave linked to attention control) from children between the ages of four and eight who experienced a minor sleep reduction from their baseline amount of sleep for seven consecutive nights. Behavioral attention information was collected using the NEPSY Visual Attention subtest. Event-related potentials (ERPs) were then recorded after one week of baseline sleep and after a second week of one-hour sleep restriction using a Geodesic Sensor Net. Actigraphy recordings verified sleep times during both weeks.

As per the results, the ERPs accounted for 44 percent of the total variance in predicting NEPSY Visual Attention scores after the children's sleep was reduced for one week.

"These data are interpreted to suggest that neutral based risk factors can signal the cognitive resilience of individuals in handling subsequent sleep loss," said Millis......... Posted by: Beverly      Read more         Source

June 10, 2007, 9:26 PM CT

"Nurse Cells" Make Life and Death Decisions

"Nurse cells" play an important role in deciding which developing infection-fighting cells, called T cells, live and which die, as per research funded by the National Science Foundation (NSF) and published in the recent issue of the journal Experimental Biology and Medicine.

The infection-fighting cells, known as thymocytes or T cells, live in the thymus, an organ in the upper portion of the chest. Loss of the thymus results in severe immunodeficiency and increased susceptibility to infection. The function of T cells produced by the thymus is to recognize harmful invaders. Once invaders have been identified, T cells then attempt to eliminate disease-infected cells.

"In early studies, it was suggested that thymic nurse cells only removed non-functional thymocytes," said Eve Barak, program director in NSF's Division of Molecular and Cellular Biology. "This research shows that nurse cells are performing a much bigger role in the thymus than we thought".

Thymic nurse cells were given their name because of their close relationship with thymocytes. These nurse cells have been reported to take up as a number of as 50 destined-to-die thymocytes into their own cell bodies.

Thymic nurse cells were discovered in 1980. Their existence was debated because a number of researchers found it difficult to think that a cell could internalize another cell, said Jerry Guyden, a biologist at the City College of New York and lead researcher......... Posted by: Beverly      Read more         Source

June 10, 2007, 9:21 PM CT

Gazing up at the Man in the Star?

Using a suite of four telescopes, astronomers have captured an image of Altair, one of the closest stars to our own and a fixture in the summer sky.

While astronomers have recently imaged a few of the enormous, dying, red-giant stars, this is the first time anyone has seen the surface of a relatively tiny hydrogen-burning star like our own sun.

"The galaxy is shaped by the effects of relatively rare but powerful hot, rapidly rotating stars," says John Monnier of the University of Michigan, the lead author on the study that will appear on Science Express on May 31, 2007. "These stars have more in common with Altair than our own sun and understanding Altair will allow us to better understand how these influential stars scattered throughout the galaxy operate".

Monnier was part of an international team of astronomers that captured the image using four of the six telescopes at a facility on Mt. Wilson, Calif., operated by the Center for High Angular Resolution Astronomy (CHARA) at Georgia State University in Atlanta with partial support from the National Science Foundation (NSF).

The CHARA telescopes were able to make the breakthrough observation because they were outfitted with a novel system to clean up some of the distortions from Earth's atmosphere, a technology called the Michigan Infrared Combiner, developed with NSF support at the University of Michigan in Ann Arbor. Recent advances in fiber optic telecommunication technology made this new combiner possible......... Posted by: Beverly      Read more         Source