Wednesday, February 24, 2010

Space shuttle Endeavor's Mission specialist onboard

Floating just below the International Space Station, astronaut Nicholas Patrick put some finishing touches on the newly installed cupola space windows last week. Patrick was a mission specialist onboard the space shuttle Endeavor's recently completed STS-130 mission to the ISS.

Monday, February 22, 2010

Space Shuttle Endeavour Completes Mission, Lands at KSC

Shuttle Launch Integration Manager Mike Moses said that space shuttle Endeavour's landing capped off a flawless mission. "The crew did an outstanding job," Moses said, referring to the complex task of installing Tranquility and its seven-windowed cupola to the International Space Station. "The landing today went as smooth as you can hope for -- by the numbers."

Moses wrapped up his remarks about the STS-130 mission by saying, "It was an outstanding mission -- I can't be happier with the success we had and look forward to repeating that on our next mission."

Shuttle Launch Director Mike Leinbach was extremely pleased with Endeavour's condition."One of the most magical things we get to do here at Kennedy Space Center is walk around the orbiter after a mission from space. She looks really, really good," Leinbach said.

Leinbach also congratulated Norm Knight and his team in the Mission Control Center at NASA's Johnson Space Center in Houston for a job well done.

Space shuttle Endeavour is home after two weeks in space, having delivered the final U.S. module and a "room with a view" to the International Space Station. STS-130 Commander George Zamka guided Endeavour to a landing at the Kennedy Space Center's Shuttle Landing Facility at 10:20 p.m. EST, to wrap up a 5.7 million mile mission.

Zamka, pilot Terry Virts and Mission Specialists Kathryn Hire, Stephen Robinson, Nicholas Patrick and Robert Behnken left behind more than 36,000 pounds of hardware that included the Tranquility Node 3 and the unique cupola providing a 360-degree view through seven windows.

Behnken and Patrick conducted three spacewalks during the mission totaling 18 hours, 14 minutes. That brings the totals for station assembly to 140 spacewalks and more than 873 hours.

Wednesday, February 17, 2010

Termite Battles May simplify Evolution of Social Insects

Natural selection argues for small biological changes that yield greater chances of survival and successful reproduction. Yet, that process does not square well with the evolution of social insects, particularly when their colonies can have over a million non-reproductive members.

A new study of termites may have the answer for such an evolutionary question, first posed by Charles Darwin nearly 150 years ago: How does natural selection produce insect "worker" and "soldier" offspring who never reproduce, find mates or start their own colonies?
Apparently, the answer is because for offspring, there is no place like home.

"This question about the evolution of social behavior among insects really intrigued me," said lead researcher and University of Maryland evolutionary biologist Barbara Thorne, who has spent nearly 30 years pursuing the answer.

"Social insects are extremely successful and dominant in many different habitats all over the world, yet we don't understand how this thriving but complex colony structure evolved. It's why I got involved in these studies when I was a young graduate student."

Thorne's recent research, funded in part by the National Science Foundation (NSF), puts forth a novel theory that it was more advantageous for early termite offspring to stay at home and help their parents than risk dangerous attempts at creating independent colonies away from the nest where they would be more susceptible to predators. The termite youngsters had the best opportunity to take over the reproductive throne when their parents were killed by neighbors.
"The incentive to remain home with their siblings and inherit their parents' estate could provide a missing link to the evolution of sterility among social insects," Thorne said.

Thorne and her colleagues Philip Johns and Ken Howard, both now at Bard College, and fellow Maryland colleagues Nancy Breisch and Anahi Rivera, staged meetings between colonies of neighboring Dampwood termites--the most primitive living termites with traits similar to hypothesized ancestors--and also analyzed the termites' genetic markers.

Her team's research shows that when two neighboring termite families within the same log meet, they battle, often leading to the deaths of one or both families' kings and queens.This paves the way for replacement "junior" kings and queens to develop from either or both colonies' worker offspring. In other words, sterile termites can become reproducers when their parents are killed, becoming the main progenitors for the colony.

Pheromones produced by healthy kings and queens normally suppress gonad development in "helper" classes, and when the kings and queens die, the pheromones disappear or diminish. As a result, suppression lifts and nonrelated, "sterile," helper offspring from both colonies are able to become new "reproductives" and assume the throne.

"Assassination of founding kings and queens may have driven young termite offspring to remain as non-reproducing workers in their birth colonies," said Thorne. Rather than risk dangerous attempts at initiating independent colonies outside the nest, remaining at home may have given them a better opportunity to become reproducers.

It also turns out that hundreds of king and queen founding pairs simultaneously colonize the same dead tree, giving the insects greater opportunity to meet and battle their neighbors. When kings and queens are killed, termites from the unrelated families join forces and cooperate in a larger, stronger group in which new reproductive termites can emerge from either or both colonies' worker ranks. Termites from the two families may even interbreed.

Because these young colonies are relatively small, the offspring--that remain as helpers in their parents' nests--have a reasonable chance of inheriting the family's resources and becoming reproductive termites.

"The merged colony also has a size advantage in its next battle with a neighbor," Thorne said. "Thus, both unrelated families benefit following colony encounters."

"Ants, bees and wasps also have highly social colonies with queens and sterile helpers, but they have an unusual genetic system that complicates study of their social origins," Thorne said. "Termites have both kings and queens, and their colony organization is amazingly convergent with the ants, bees and wasps, yet they (termites) evolved completely independently and have a more normal genetic system. Termites haven't received a lot of attention from evolutionary biologists, yet their case may reveal some fundamental principles."

The primitive living termite featured in the research, genus Zootermopsis, shares social, developmental and habitat characteristics with ancient ancestors, and thus serves as a model system to draw inferences regarding how highly social behavior evolved in these insects 140 million years ago. Once primitive termites had an incentive to stay at home in their parents' nest due to the possibility of early or "accelerated" inheritance, that behavior became fixed and over evolutionary time, termite social behavior passed through what Harvard biologist Edward O. Wilson describes as the "point of no return."

"These findings demonstrate how ecological factors could have promoted the evolution of social organization by accelerating and enhancing direct fitness opportunities of helper offspring, rendering relatedness favoring kin selection less critical," Thorne said.

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Monday, February 15, 2010

Climate change has a major impact on tropical lizards and their ecosystems

tropical_lizardLizards are ectotherms--animals whose body temperatures vary with surrounding temperatures. Ectotherms, which account for the largest population of animals on Earth, are found in the highest concentrations in tropical areas.

Since the 1940s, scientists have known that lizards regulate their body temperatures by moving between sun and shade. Less well understood has been tropical lizards' adaptability to changes in the temperature and availability of shade in their environment.

A study conducted by Raymond Huey of the University of Washington and colleagues was designed to improve our understanding of these variables. The Huey study, funded by the National Science Foundation (NSF), involved:

• Analyzing previous climate data and comparing it to lizard body temperatures in the Amazon rainforest between 1985 and 2005 and in the Caribbean in the 1970s. "In the 1970s a bunch of us were running around the Caribbean with thermometers taking lizard body temperatures for reasons totally unrelated to climate warming," Huey said. "But we can use our data from a third of a century ago as a baseline to now predict how lizards at different latitudes would respond to climate change."
• Measuring the "fitness" of tropical lizards and moderate-climate lizards in the laboratory, i.e., how fast they run at various temperatures.

Huey and his team found that in the laboratory, tropical lizards remained at their peak fitness level within narrow ranges of temperatures that reflected average temperatures in tropical climates. When temperatures exceeded these average temperatures even slightly, the speed at which the lizards ran decreased and their responses became relatively sluggish.

Huey's team also found that the average temperature in the Caribbean forest has risen three and a half degrees, from 80 degrees Fahrenheit to 83.5 degrees F. The rise in temperature has caused these lizards to become heat stressed and not able to function as well. This is important because the more slowly lizards move, the more vulnerable they are to predators; this vulnerability may reduce the sizes of their populations.

Why are tropical lizards apparently more sensitive to temperature increases than moderate-climate lizards? Probably because lizards that live in topical forests, which are consistently hot and humid both day and night almost year-round, are only exposed to slight temperature changes and have not evolved to adapt to significant temperature increases. Therefore, lizards living in tropical forests are relatively sensitive to temperature increases caused by climate change, and their fitness levels decrease as temperatures rise.

By contrast, in many higher latitude climates, lizards experience a wide range of temperatures on a daily and seasonal basis. For example, daytime temperatures in desert regions in the southwest United States may soar well over 100 degrees F, and then dip into the 60s during evening hours. Because lizards living in these areas have evolved to adapt to such relatively extreme temperature changes, they may adapt to increases in temperature caused by climate change relatively easily. Therefore, their fitness levels are less affected by climate warming than are tropical lizards' levels.

Furthermore, because tropical lizards rely on the shade of the forest to help them regulate their body temperature, changes in the canopy structure caused by climate change may indirectly affect their ability to cool down.

Effects of temperature rise will ultimately affect all of us, according to Laurie Vitt, one of Huey's fellow researchers on the project.

Thursday, February 11, 2010

Permafrost could be Global Warming's Ticking Time Bomb

The terrain of the North Slope of Alaska is not steep, but Andrew Jacobson still has difficulty as he hikes along the spongy tundra, which is riddled with rocks and masks multitudes of mosquitoes.

Jacobson, a professor of earth and planetary sciences at Northwestern University, extracts soil and water samples in search of clues to one of global warming's biggest ticking time bombs: the melting of permafrost.

Permafrost, or frozen ground, covers approximately 20 to 25 percent of the land-surface area in the northern hemisphere, and is estimated to contain up to 1,600 gigatons of carbon, primarily in the form of organic matter. (One gigaton is equivalent to 1 billion tons.)By comparison, the atmosphere now contains around 850 gigatons of the element as carbon dioxide.

"Permafrost historically has served as a carbon sink, largely isolating carbon from participating in the carbon cycle," says Jacobson, whose research is funded by the National Science Foundation (NSF) and the David and Lucile Packard Foundation. "However, global warming could transform the Arctic into a new carbon source by accelerating the rate of permafrost melting. This undoubtedly would have a dramatic effect on the global carbon cycle."

Jacobson says the key concern is that permafrost carbon will oxidize to carbon dioxide as melting accelerates, causing a positive feedback to global warming. A vicious cycle is created as a warmer climate facilitates more carbon release, which in turn favors more warming.

So Jacobson and his colleagues collect river water and soil samples near NSF's Toolik Long-Term Ecological Research station, approximately 250 kilometers (km)--155 miles--north of the Arctic Circle. The Dalton Highway--built as a supply road to support the Trans-Alaska Pipeline System--provides the only access to the site.

"Planning constitutes a large part of our day--looking at maps, figuring out where to go and how to get there," he laughs. "Fieldwork is typically fraught with vehicle problems, poor roads and bad weather. One thing you can always count on is that every expedition is exciting."

While a logical first step for modeling global warming is quantifying carbon flow, unresolved complexities surrounding the Arctic carbon cycle make it difficult to create models for that element.

Jacobson and his team take a complementary approach by analyzing naturally occurring isotopes of other elements, such as calcium and strontium, which track permafrost melting and therefore provide insight into carbon release.

Initial data show that rivers and permafrost have distinctly different calcium and strontium isotope compositions.When permafrost thaws during the summer and melts into rivers, the rivers show calcium and strontium isotope compositions that approach those for permafrost. Jacobson hypothesizes that in a warmer world, the permafrost signature in rivers will be more pronounced for longer periods of time.

Changes in the isotope composition of rivers can relate to changes in the release of carbon. So the calcium and strontium isotope composition of Arctic rivers can track the impact of warming on permafrost stability and carbon dioxide release.

"The ultimate goal is to establish a baseline to which future changes can be compared," Jacobson says. "Several years from now, we can compare real changes to model predictions and improve our understanding of how the system works."

Monday, February 08, 2010

Soybean – The Interesting Legume

Soybean is an interesting plant. It provides a valuable protein source for human and animal consumption, it is an important feedstock for biodiesel production, and it interacts with soil-borne bacteria (Rhizobia) that capture atmospheric nitrogen and store it in the soil, a beneficial side-effect utilized during crop rotation. In an effort to unlock the full power of this plant, scientists have sequenced the soybean genome.

“Most people are familiar with sequencing of the human genome,” begins Jeremy Schmutz, faculty scientist at Hudson Alpha Institute for Biotechnology, a partner laboratory with the DOE Joint Genome Institute (JGI). “The soybean genome was sequenced to provide scientists a better understanding of plant productivity, complex biochemical pathways, such as oil production, and pest and pathogen resistance just like the human genome is helping scientists to understand human diseases.”

The scientific team, led by Schmutz, used a process called “whole genome shotgun” to sequence the entire genome as a single effort. “With this technique, we were able to sequence and order the genome at one time so the scientific community could go directly from the genome sequence to breeding new varieties of soybean” said Schmutz.

At first glance, the soybean genome is an impressive size - 1,115 mega -base pairs (Mbp) (1,115,000 base pairs) – about 1/3 the size of the human genome, which contains approximately 3,000 Mbp. But by plant standards, the soybean genome is relatively small and tractable for genomics research.

The soybean genome, like other plant genomes, displays a feature called polyploidy. Schmutz explains, “During seed generation, whole regions of the genome can be duplicated. These duplications can infer a competitive advantage to the plant allowing it to thrive.”

Tuesday, February 02, 2010

Angry Flies are used in the Explain Human Aggression

Recently, biologist David Anderson set out to learn whether flies, like bees, can get angry--part of a broader effort to study how animal behavior relates to genetics.

"Every time you swat a fly away from your hamburger, it seems to come back to the food more aggressively or persistently," Anderson said. "People might wonder about whether there's such a thing as an 'angry' fly, but no one would challenge the idea of an angry bee--especially someone who's been stung by one."

To test his hypothesis, Anderson--who currently has two projects funded by the National Science Foundation (NSF) and who is a Howard Hughes Medical Institute (HHMI) Investigator at Caltech--created an experiment modeled after the traditional "bees-at-the-picnic-table" scenario using Drosophila, the common fruit fly (or more accurately, the vinegar fly).

"We developed the 'puff-o-mat' apparatus, with the idea of putting some fly food at one end, and then blowing the flies away from the food with a gentle puff of air every time they got close to it," he said. "Then we measured whether the flies became more agitated and approached the food more aggressively after experiencing this frustrating experience several times."As it turned out, they didn't even need the food.

"To our surprise," Anderson said, "simply blowing the flies off their feet several times in a row was sufficient to get them riled up. So we decided to focus on that--the agitation response--because it was much simpler to set up without the food, and without starving the flies. The part with the food never made it into the final paper," he added, referring to a study published in the journal Nature in early December, 2009.

The flies showed a primitive emotion-like behavior. Prompted by a series of brisk air puffs delivered in rapid succession, the flies ran around their test chambers in a frantic manner, and kept it up for several minutes. Even after the flies had calmed down, they remained hypersensitive to a single air puff.

The research showed that Drosophila produces a pheromone--a chemical messenger--that promotes aggression, and directly linked it to specific neurons in the fly's antenna. Anderson and his colleagues believe that the findings ultimately may be relevant to the relationship between the neurotransmitter dopamine and attention deficit hyperactivity disorder.
The brain of Drosophila contains about 20,000 neurons, and has long been considered a valuable system with which to study the genetic basis of learning, courtship, memory and circadian rhythms.

In recent years, Drosophila research has also been a powerful tool with which to study emotions. Most of the genes in the fruit fly are also in humans, including neurons that produce brain chemicals associated with several psychiatric disorders.

For example, in an earlier study, the researchers demonstrated how Drosophila hunkers down and stops moving in response to a steady wind--a sensory tool that could improve how the insects navigate during flight, and could help scientists learn more about the nervous system.
Anderson came to this field of research after amassing an impressive record studying the developmental biology of neural stem cells in mice. He decided he wanted to try something new. Switching scientific directions mid-career is always risky, it takes courage and a willingness to fail, but Anderson was game.