Senin, 31 Agustus 2009

Ted Talk (April 2009) Bonnie Bassler: The secret, social lives of bacteria

The great thing about TED talks is that they are designed to take information and show why it has profound implications. This marriage of data and eureka, leads to the entertaining and engaging speeches TED is known for.

"Bonnie Bassler discovered that bacteria "talk" to each other, using a chemical language that lets them coordinate defense and mount attacks. The find has stunning implications for medicine, industry -- and our understanding of ourselves."

Synthetic Biology on KQED QUEST

Apologies a million times for the lack of posting. Thanks to the troubled economy my day job is dominating my life right now, so I hardly have time to post. Thanks to everyone who keeps this blog going strong! We got over 90 visitors today!

Step by Step: How to Prepare a Slide of Cells

"Middle and Secondary Level Biology: How to Prepare a Slide of Cells. This video details the step by step instructions of how to make a slide using cheek cells. Students learn the process of preparing and staining the slide for viewing and comparison. This is a classroom produced instructional science video intended for middle and secondary studies and homework help."

SchoolWAX TV VIDEO: The formation of Lipids

SchoolWAX TV video: Glycolosis (10 enzymes that make possible the 10 steps in the breakdown of sugar)

SchoolWAX TV VIDEO: The formation of Proteins

SchoolWAX TV VIDEO: Great Animation/narration of the formation of Carbohydrate Bonds

"This video describes the bonding structure of four elements in the periodic table (hydrogen, oxygen, nitrogen, and carbon) to form carbohydrates. This video is a part of the Cassiopeia collection, an effort to make science education videos available for free to anyone who wants them. The vision is that if a concept can be visualized, then understanding is not far behind. Each video is self-contained but also embedded in a larger science fiction story intended to generate interest in the sciences."

Leaf Pigmentosis (Leaf Pigment Chromatography)

"his video is a lab cast created by John Sowash. It reviews a hands on biology project separating pigments in leaves through a process called chromatography. For resources related to this lab including student worksheets and teacher guides visit"

Kamis, 27 Agustus 2009

Can You Taste Bitter Foods?

About 25% of the human population does not perceive vegetables such as broccoli, cabbage, or Brussels sprouts as bitter-tasting. The rest of us perceive these vegetables as either mildly bitter or obviously bitter. These differences are determined by a gene that has two variations, or alleles – one for “bitter taster” and one for “non-taster”. The bitter taster allele is dominant, so if you have at least one copy of it you will perceive Brussels sprouts as mildly or intensely bitter.

At what point in human evolution did the ability to taste bitter foods first appear? Recent DNA analysis of a bone of a Neanderthal (an extinct line of archaic humans) indicates that they possessed the bitter taster allele. Therefore, the ability to taste bitter foods probably evolved more than half a million years ago, before Neanderthals and modern humans diverged from a common ancestor.

Evolutionary biologists believe that the ability to perceive bitter taste may have discouraged early humans from eating bitter-tasting plants, some of which are toxic if ingested in large quantities.

Kamis, 20 Agustus 2009

Measuring Groundwater Depletion

Scientists are using satellite data to measure changes in the amount of water in underground aquifers. How do they do it? Satellite speed is affected by the pull of gravity, which is partly determined by how much water is underground near Earth's surface. As the first of two satellites approaches a region of the Earth with a large underground aquifer, the pull of gravity increases and the satellite speeds up briefly, increasing the distance between it and a trailing satellite. As the second satellite passes over it too speeds up briefly, closing the gap again. By measuring the changes in distance between the two satellites as they pass over the aquifer and then comparing those distances from year to year, scientists can determine changes in the pull of gravity over time and then estimate how much water has been gained or lost.

Using this technology, scientists have discovered that in just six years, one of the largest aquifers in India has lost a volume of water equal to a lake 30 feet deep and nearly 5,000 square miles in surface area. Most of the groundwater consumed in the region is used for agriculture. Nobody knows how large the aquifer really is or how long it would take to deplete it, but losses of this size just are not sustainable in the long run.

We can expect more of this kind of useful information as the satellite technique becomes more sophisticated. But will we choose to change our water use practices as a result of what we learn?

Sabtu, 15 Agustus 2009

Breast-Feeding and Breast Cancer

A recent study in the Archives of Internal Medicine raises the possibility (but does not entirely prove) that breast-feeding may lower the risk of breast cancer among women at high risk for the disease. The study gathered data from over 60,000 women who had reported at least one pregnancy by 1997. Among women with close relatives who developed breast cancer, those who breast-fed for a period of time had only 41% as many breast cancers by 2005 as women who had never breast-fed. The lowered cancer incidence was only seen among women at high risk for breast cancer; women with no family history of breast cancer did not benefit from breast-feeding.

Why doesn’t this study prove once and for all that “breast-feeding prevents cancer”? Because it only shows an association between breast-feeding and lowered cancer risk - cause-and-effect has not been proved. Perhaps women who choose to breast-feed are more health-conscious overall. Perhaps they exercise more or have a better diet, and that’s actually what lowered the cancer risk. Further research will be needed to tease out the details.

Selasa, 11 Agustus 2009

Is Running Hard on Knees?

Runners are often told (usually by non-runners) that running is hard on their knees. According to commonly held belief, the constant pounding wears out or damages knee cartilage and leads to either knee injury or an increased likelihood of osteoarthritis later in life.

But the available scientific evidence suggests that running is not a risk factor for knee osteoarthritis, and may in fact keep you healthier later in life. In one study, runners were compared to age-matched non-runners over an 18-year period. There was no difference in the rate of development of osteoarthritis between the two groups. In another study, overall disability rates in runners increased at only one quarter of the rate seen in age-matched sedentary persons.

A major risk factor for knee osteoarthritis is not running per se; its having had a previous knee injury. That is why there is so much osteoarthritis among former N.F.L. football players and former soccer players. But if you’re a recreational runner and manage to stay injury-free, don’t worry about wearing out your knees – just keep running!

Kamis, 06 Agustus 2009

The Spleen Stores Monocytes

Shortly after severe tissue damage such as that caused by a heart attack or an infection, the number of monocytes, the white blood cells that eventually mature into macrophages, increases dramatically in the blood. These new monocytes appear too quickly to have been newly produced from stem cells in bone marrow. So where do they come from?

Apparently they come from the spleen. The spleen stores up to ten times as many monocytes as there are in the bloodstream at any one time. When a tissue is injured the spleen releases its stored monocytes, which then migrate to the site of injury, develop into macrophages, and participate in the cleanup and repair process. It’s a pretty efficient use of resources, when you think about it - a virtual army of monocytes is kept on standby, ready to be deployed when needed.

Senin, 03 Agustus 2009

Buying/Selling Kidneys

A Brooklyn businessman named Levy-Izhak Rosenbaum was arrested in New Jersey in 2009 for allegedly trying to broker the purchase of a kidney for $160,000. According to the criminal complaint filed against him, Mr. Rosenbaum told an undercover agent that he could arrange for a live kidney donor from Israel, and that they would then fabricate a fictitious “relationship” between the donor and the recipient so that the hospital in the U.S. would not become suspicious.

The Rosenbaum case is just one example of the shadowy black market in human organs worldwide. The World Health Organization estimates that about 10% of the more than 60,000 kidneys transplanted each year come from living donors who have sold their kidneys strictly for money. The temptation is hard to resist, especially for donors from poor countries where the choice may come down to selling a kidney or selling a child. The practice is not even illegal in some countries (Pakistan is an example), and as a result those countries are rapidly developing thriving “transplant tourism” enterprises.

What, if anything, could be done about the shortage of organs for transplantation?
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