Stories tagged Life Science

Sep
16
2006

Loud this time of year: Fork-tailed bush katydid (Photo courtesy Jenn Formann Orth)
Loud this time of year: Fork-tailed bush katydid (Photo courtesy Jenn Formann Orth)

This article, by Tyler Rushmeyer, appeared in the local news section of today's Pioneer Press:

Racket bugging residents: Night music made by katydid colony
Many White Bear Lake residents were baffled when they started hearing a new sound reverberating through their neighborhoods.
As night falls, a loud "yack, yack" sound has filled the air. "It sounds like a tropical rainforest on my block," said White Bear Lake resident Mark Nevala, one of several people to call city officials asking about the noise.
The culprit: katydids, loud insects performing mating calls by rubbing their wings together. The mating season should last into early October.
Closely related to grasshoppers and crickets, katydids are spread throughout Minnesota. The bugs residents are hearing are the northern katydid species, said Dick Oehlenschlager, assistant curator and collections manager for biology at the Science Museum of Minnesota.
"They move in colonies and shift every year, and this year their colony seems to have taken residence in the Twin Cities area," he said.
The insects--about 2 inches long and bright green, with long, coiled antennae--are near-motionless during the day and reside on the leaves of trees. But soon after dusk, they become active. They are difficult to spot, Oehlenschlager said, which is why many people are confused about where the noise is coming from.
"Even I didn't know what I was hearing the first couple times I came in contact with them," Oehlenschlager said.

Look for our new fall phenology section, featuring other seasonal behaviors of insects and birds, coming to the Mississippi River Gallery and the Buzz website after next week.

Aug
29
2006

A new paper published in the Procedings of the National Academy of Sciences suggests that, as parents preferentially select boys over girls and gender imbalances grow, we'll see rising levels of anti-social and violent behavior.

Stella: Isn't she worth just as much as a baby boy? (Photo by Liza Pryor)
Stella: Isn't she worth just as much as a baby boy? (Photo by Liza Pryor)

"There are already an estimated 80 million missing females in India and China alone."

(According to the World Bank, in 2004 48.6% of China's population and 48.7% of India's population were female. By contrast, females made up 49.1% of the total population in East Asia, and 52.1% in all of Europe and Central Asia.)

The Reuters news report says,

"'This trend would lead to increased levels of anti-social behavior and violence, as gender is a well-established correlate of crime, and especially violent crime,' [the authors] said, adding the trend would threaten stability and security in many societies."

The authors of the paper call for "measures to reduce sex-selection and an urgent change in cultural attitudes." But that seems easier said than done.

Do you think it's possible to change cultural attitudes about gender preference? It's easy to say this is a problem of East Asian cultures, but what about the US? Do we have cultural preferences about our children's genders, too?

Aug
17
2006

Green green grass: Is genetically engineered grass a form of nanotechnology?Photo courtesy StarMama
Green green grass: Is genetically engineered grass a form of nanotechnology?
Photo courtesy StarMama

A type of grass created by bioengineers in a lab has escaped out into the environment for the first time--at least that we've noticed.

The grass is being developed to resist the common herbicide Roundup. Scotts Miracle-Gro Company and Monsanto, who are engineering this grass, hope to use it on golf courses so that Roundup could be sprayed to kill weeds without killing the grass.

So what's this got to do with nanotechnology?

Well, I've been doing lots of research into nanotechnology and the social concerns around its use. Just like bioengineered crops, people worry that we don't have a clue what could happen if these plants or particles, in the case of nanotechnology, escape into the environment.

Could the genes from this Roundup resistant grass find their way into wild grasses? If they do it might be that much harder to eliminate weeds that grow wild in our environment.

Okay, but really, what about this nanotech stuff?

Well, this story got me and some of my coworkers thinking about the definitions of genetic engineering and nanotech. In genetics we are manipulating DNA at the nanoscale. In nanotechnology we are manipulating molecules and atoms at the nanoscale. Despite having many people tell me that they are unique I still don't totally get it.

I think it mostly lies in the methods with which the different sciences go about manipulating things. The processes that genetic engineers use to create a new kind of grass are unique from those that nanotech scientists use to engineer something like carbon nanotubes.

So what do you think? I will ask around and see if I can get some answers to the question, "Is genetic engineering a type of nanotechnology?"

Aug
09
2006

Comparison of body temperatures: A plot of the relationship between average body temperature (°C) and the logarithm of body mass for dinosaurs and modern crocodiles.  This graph potentially shows the accuracy of the formula by applying it to modern crocodiles. Chart  courtesy Gillooly JF Allen AP, Charnov EL (2006) Dinosaur Fossils Predict Body Temperatures. PLoS Biol 4(8): e248.
Comparison of body temperatures: A plot of the relationship between average body temperature (°C) and the logarithm of body mass for dinosaurs and modern crocodiles. This graph potentially shows the accuracy of the formula by applying it to modern crocodiles. Chart courtesy Gillooly JF Allen AP, Charnov EL (2006) Dinosaur Fossils Predict Body Temperatures. PLoS Biol 4(8): e248.
The question regarding whether dinosaurs were warm-blooded or cold-blooded has been debated for decades. Currently, most scientists believe that dinosaurs were warm-blooded and used internal mechanisms to maintain a constant body temperature. However, what that internal body temperature was could have fluctuated depending on the size of the dinosaur, making it possible for dinosaurs to have been both.
The bigger the hotter
Researchers at the University of Florida devised a mathematical formula that describes the connection between temperature, growth rate and biomass across a wide range of modern creatures. They then applied this formula to newly available fossil data on the growth rates of eight dinosaur species.
The equation showed that the bigger a dinosaur was the hotter is was. Smaller dinosaurs had internal body temperatures of around 77º Fahrenheit, which was close to the average air temperature of their time, so could have regulated their body temperatures much like modern cold-blooded reptiles. As dinosaurs grew larger, and the ratio of their surface area to volume fell, they became less efficient as dissipating their own metabolic heat. Because of this increased internal body temperature, dinosaurs probably had to develop behavioral or other adaptations to avoid overheating.
Body temperature influenced dinosaur size
One of the larger dinosaurs studied, Sauroposeidon proteles, weighed nearly 120,000 pounds. Applying the mathematical formula reveals that it may have had a body temperature close to 118º Fahrenheit, which is about as hot as most living creatures can get before the proteins in their bodies begin to break down. Because of this, the size of the largest dinosaurs may have been limited by their internal body temperatures.

Jul
28
2006

A University of Iowa researcher, Dr. James Gill, has just shown that people can catch a non-threatening kind of bird flu (NOT the H5N1 strain) from wild birds.


Duck hunter's dog: (Photo by Blaine Hansel)

Gill tested blood from 39 duck hunters for antibodies that would prove infection by any of a dozen kinds of bird-based influenza. Several hunters had antibodies to H1, H2, and H3 strains, which have adapted to humans and are now routinely seen in people. But one hunter tested positive for H11N9, which is not seen in humans.

The hunter was a healthy, 39-year-old man who'd been hunting since he was 8 and kills or handles hundreds of birds a year. He'd never shown any symptoms of illness.

Also, Gill found H11N9 antibodies in the blood of two Iowa Department of Natural Resources workers. Both had been banding ducks for years.

None of the infected men had any history of working with domesticated birds--an established source of bird flu transmission to humans. Instead, these cases appear to be the first documented of humans getting viruses from wild birds.

Jul
26
2006

Maria McNamara of University College Dublin, and colleagues in the UK, Spain, and US, have recovered bone marrow from 10-million-year-old fossilized bones of frogs and salamanders found in Spain.

The marrow was preserved in 3D, and still has its original texture and color. Scientists think they may be able to extract traces of protein and DNA.

Even more interestingly, the fossils prove that ancient salamanders produced blood cells in their bone marrow. Modern salamanders, on the other hand, produce blood cells in their spleens.

Last year, US scientists recovered some tissue resembling blood vessels from a 65-million-year-old Tyrannosaurus rex fossil. They also found traces of what appeared to be red blood cells. (More on the T. rex find.)

And now that they're looking, scientists think they may find examples of preserved bone marrow in many fossils, raising the possibility of analyzing the proteins and DNA of lots of long-extinct organisms.

Jul
21
2006

We've had mourning doves nesting in our backyard evergreen trees all summer.

Mourning dove: You can see the messy nest and a chick's head peeking out. (Photo by Ken Kornack)
Mourning dove: You can see the messy nest and a chick's head peeking out. (Photo by Ken Kornack)

They're good parents--far more attentive than the human ones who share the space! They lay two eggs at a time, and almost never leave them alone. The male usually incubates from midmorning until late afternoon, and the female tends them the rest of the time. (Warning: gross fact ahead!) Mourning doves of both sexes feed their hatchlings something called "pigeon milk"--a substance that oozes from the lining of the parent's crop and contains more protein and fat than either human or cow's milk. Hatchlings eat nothing but pigeon milk until they're three days old; after that, they're gradually weaned onto a diet of seeds. The parents continue to feed the hatchlings until they're totally feathered out.

The crazy part is that mourning doves can produce five or six sets of chicks each year. (This may be one reason why mourning doves are among the ten most abundant birds in the US...) If things at the first nest are going well, the parents will build a second one nearby. One adult feeds the older chicks, while the other sits on the new eggs. It's a baby bird factory!

Right now, we have a couple of newly-fledged doves running around on the ground. I think the parents are still feeding them occasionally. And there's a new set of hungry hatchlings to feed, too. Makes me feel lazy for complaining about keeping up with my two little ones!

Listen to a mourning dove

More on mourning doves

Even more on mourning doves

Mourning doves are related to pigeons. Here's a great article on why you never see baby pigeons.

Jul
19
2006

On Tuesday, the US Senate passed three bills regarding stem cell research.

Two were pretty uncontroversial: one encouraged stem-cell research using cells from sources other than embryos—adult bone marrow or hair follicles, or umbilical cord/placental blood. (The National Institutes of Health is already spending $571 million this fiscal year on this kind of stem cell research.) And one prohibited “fetal farming”—gestating fetuses for the purpose of providing tissue and other material for research.

The House of Representatives passed the bill about fetal farming, but voted down the bill promoting alternative stem cell sources. President Bush signed the ban on the commercial production of human fetal tissue into law today.

The third bill—which President Bush has just vetoed—would have expanded federal support of medical research using embryonic stem cells. Right now, researchers using federal funds can only study a handful of embryonic stem cell lines that existed before August 2001. The failed bill would have allowed federal funding for research on stem cells from thousands of unneeded embryos created in fertility clinics. (Couples with extra embryos resulting from fertility treatments would have had the option of donating them to research instead of having them destroyed by the clinic.) An override of the veto is unlikely.

What ARE stem cells?
Stem cells are simply cells that can develop into other types of cells. They can make copies of themselves indefinitely, and can become specialized for various body tissues. They are produced by embryos and also found in limited numbers in adults, but embryonic stem cells are pluripotent--they can become almost any kind of cell in the body--while adult stem cells are more limited. Scientists think they might be able to grow replacements for damaged tissues if they can coax stem cells to become the specific types of cells needed. Stem cells could someday provide treatments or cures for cancer, spinal cord injuries, burns, strokes, heart disease, Alzheimer’s and Parkinson’s, diabetes, and other ailments.

Mouse stem cells: (Courtesy NSF)
Mouse stem cells: (Courtesy NSF)

Why not use the pre-2001 stem cell lines?

In August 2001, the Bush administration and National Institutes of Health said that 60 stem cell lines had already been developed. Federal funds would be limited to research on those lines, and could not be used to create any more. But further investigation showed that less than 22 lines were actually available, and all of them had been maintained in culture dishes with blood products from rodents--scientists say the cells can’t ethically be used to treat people because of the danger of animal viruses and other contamination. Many of the lines aren’t aging well; if they don’t keep growing and dividing, they die, and some lines are accumulating mutations and other defects. Most research is limited to six of the stem cell lines. And they aren’t a very genetically diverse lot.

But the White House says,

"The use of mouse cells is standard scientific practice. ... As the Food and Drug Administration has indicated, the resulting stem cell lines can be carefully screened to ensure they are safe for use in any future clinical trials. Drug and biological products are routinely co-cultured with animal cells with no adverse consequences for the millions of people who have benefited from them."

Why not use private money?
Some labs have produced additional stem cell lines using private money, but researchers have to be scrupulous about segregating work on the newer cells from work done with federal money. The University of California, San Francisco, for example, is spending $5 million to set up a separate stem cell research lab where scientists can work without the federal restrictions. All the lab equipment they need already exists elsewhere on campus, but it can't be used for new stem cell work.

Some states see an opportunity in the federal restrictions. California announced that state money--$3 billion over 10 years--would be available for research into embryonic stem cells and therapeutic cloning. But the initiative is being fought in court. Connecticut has an 10-year, $100 million initiative. Illinois spent $10 million last year. New Jersey spent about $25 million in the last two years. And Maryland has approved a $15 million budget. But scientists in other countries are doing far more work with embryonic stem cells than scientists in the US. And losing out now means that the US could lose the eventual commercial applications developed through such research to the countries with looser regulations.

What's the issue with using embryonic stem cells?
Harvesting stem cells destroys a developing embryo. That's the crux of the whole issue. Those who oppose embryonic stem cell research say that the potential cures promised by stem cell research supporters offer false hope to some suffering Americans while encouraging the destruction of embryos to provide the cells. Members of the US Senate, debating earlier this week, expressed the gamut of opinions:

Senator Orrin Hatch (R-Utah) said,

"I do not question that an embryo is a living cell. But I do not believe that a frozen embryo in a fertility clinic freezer constitutes human life."

Senator Bill Frist (R-Tenn.), the Senate majority leader and a transplant surgeon, said,

"I believe that the progress of science and a pro-life position demand that Congress can send a message. I hope that we can redeem this loss of life in part by using these embryos to seed research that will save lives in the future."

Senator David Vitter (R-Louisiana) said,

"...I firmly believe that [neither] Congress, independent researchers nor any human being should be allowed, in effect, to play God by determining that one life is more valuable than another."

Senator Tom Coburn (R-Oklahoma), who is also a physician, said,

"The fact is, there is not one cure in this country today from embryonic stem cells."

Senator Tom Harkin (D-Iowa) said,

"So the choice is this ... throw [the embryos] away or use them to ease suffering and, hopefully, cure diseases."

Senator Sam Brownback (R-Kansas) said,

"We do not need to treat humans as raw material."

and

"It is immoral to destroy the youngest of human lives for research purposes. We don't need to do it."

Public opinion polls show that 70% of Americans support embryonic stem cell research. What do YOU think? Should the US government help fund it?