Category Archives: Life Science

Overuse of Antibiotics

Stomach Bug Mutates Into Medical Mystery – Antibiotics, Heartburn Drugs Suspected

Shultz is one of a growing number of young, otherwise healthy Americans who are being stricken by the bacterial infection known as Clostridium difficile — or C. diff — which appears to be spreading rapidly around the country and causing unusually severe, sometimes fatal illness.
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“It’s a new phenomenon. It’s just emerging,” said L. Clifford McDonald of the federal Centers for Disease Control and Prevention in Atlanta. “We’re very concerned. We know it’s happening, but we’re really not sure why it’s happening or where this is going.”

It may, however, be the latest example of a common, relatively benign bug that has mutated because of the overuse of antibiotics.

Articles on the overuse of anti-biotics are available via the Curious Cat directory. From the US Center for Disease Control – Antibiotic / Antimicrobial Resistance section:

Antibiotic use promotes development of antibiotic-resistant bacteria. Antibiotic resistance occurs when bacteria change in some way that reduces or eliminates the effectiveness of drugs, chemicals, or other agents designed to cure or prevent infections. The bacteria survive and continue to multiply causing more harm. Widespread use of antibiotics promotes the spread of antibiotic resistance. While antibiotics should be used to treat bacterial infections, they are not effective against viral infections like the common cold, most sore throats, and the flu.

Unfortunately the continued overuse of antibiotics is increasing the danger of deadly antibiotic resistant bacteria. This problem is a significant challenge not only due to the scope of the consequences (which are huge) but due to the nature of the problem. Many thousands, hundreds of thousands maybe even millions of poor use of antibiotics incrementally put everyone at risks. But each of those individual steps of poor use of antibiotics is by itself not likely to be deadly.

Due to the way we tend to think about problems (searching for one simple cause or thing to blame and fixing that one thing), the cause of antibiotic resistance provides an opportunity for the millions of bad actions to go unchecked. Only after catastrophic consequences are recognized, and put in the proper context, are we likely to give this issue the attention it deserves. Thankfully CDC and others are trying to get us to take this issues seriously now. However, the risks are huge and each person (doctors, patients, consumers [use of antibiotics on animals used as food is a huge part of the problem], government regulators…) taking small actions that make the situation worse often don’t see any need to take more responsibility.

Wasps Used to Detect Explosives

Wasps Used to Detect Explosives, podcast from NPR:

The “Wasp Hound” is a device that utilizes trained wasps to detect explosives and other odors. Joe Lewis, research entomologist with the USDA Agriculture Research Service and the Wasp Hound’s lead inventor, discusses the device.

Wasps could replace bomb, drug dogs, USA Today:

Scientists say a species of non-stinging wasps can be trained in only five minutes and are just as sensitive to odors as man’s best friend, which can require up to six months of training at a cost of about $15,000 per dog.
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“There’s a tremendous need for a very flexible and mobile chemical detector,” said U.S. Department of Agriculture entomologist Joe Lewis, who has been studying wasps since the 1960s.

Parasitic Wasps Learn and Report Diverse Chemicals with Unique Conditionable Behaviors by Olson, D.M., Rains, G.C., Meiners, T., Takasu, K., Tertuliano, M., Tumlinson, J.H., Wackers, F.L., Lewis, W.J. 2003. Chemical Senses. 28:545-549.

Gene Linked to Fish and Human Pigmentation

A Fish of a Different Color:

Until now, the genetics underlying human skin pigmentation have remained a mystery. But while studying the zebrafish–a fish common to household aquariums and research laboratories–a team of interdisciplinary scientists found a gene that plays a major role in human coloration.

Besides unraveling some of the mysteries of human variation, the research, which is featured on the cover of the Dec. 16 issue of Science, has implications for understanding a host of human diseases including cancer, diabetes and rickets.

Our Single-Celled Ancestors

choanoflagellates in water (photo by Melissa Mott)

Our Single-Celled Ancestors by David Pescovitz, ScienceMatters@Berkeley. Photo: propelled by their flagella, choanoflagellates move through water collecting bacteria on a collar of tentacles at the base of the cell body. (photo by Melissa Mott)

Six-hundred million years ago, a pivotal turning point in the history of life occurred. In the ancient sea, multicellular organisms evolved that are now recognized as the world’s first animals. But what was the biology of the single-celled organism that made the transition? And how did it become the common progenitor of all animals?

As always this issue of ScienceMatters@Berkeley includes excellent articles. Other articles from this issue: Extreme Biomaterials and Machines That Learn.

Massive Project Will Reveal How Humans Continue to Evolve

Massive Project Will Reveal How Humans Continue to Evolve by Gregory Mone

By comparing differences among those groups’ DNA, HapMap gives scientists a better shot at distinguishing the genetic factors involved in disease from the environmental ones. Ultimately, it will help them explain why, for instance, some people have a higher or lower risk of certain illnesses. And once scientists understand how deleterious genes affect various populations, they’ll be better equipped to develop more-effective, targeted drugs to combat them.

What Are Viruses?

What Are Viruses?, from the excellent Science In Action blog:

Viruses are small, from about 20 nanometers to about 400 nanometers in size. (A bacterial cell is generally in the range of 0.5 to 5.0 micrometers in size. A micrometer is one thousand times bigger than a nanometer, so bacteria are hundreds of times larger than viruses.)
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Viruses cannot be killed by antibiotics. Antibiotics kill or stop the growth of bacteria, not viruses. Using antibiotics to try to control viral diseases like colds and flu just hastens the day those antibiotics will be useless against dangerous bacteria, because exposing populations of bacteria to antibiotics gives them a chance to evolve defenses against the drugs.

Adventures in Synthetic Biology

Nature offers its first ever comic: Adventures in Synthetic Biology (via easternblot). Learn more about the creation of the comic. The graphics are nice, though honestly the interface to view the comic could be better. The pdf version is larger and easier to read.

I think it is great to experiment with using different ways to present scientific ideas. This comic is a good example of one of those ways. Also see several books that use cartoons to present ideas: Cartoon Guide to Genetics, Cartoon Guide to Physics and Cartoon Guide to Chemistry (all by Larry Gonick).

2005 intercollegiate Genetically Engineered Machine competition

Davidson College: Kristen DeCelle 2006 and Andrew Drysdale 2007

2005 Intercollegiate Genetically Engineered Machine Competition. Thirteen schools participated in the 2005 Intercollegiate Genetically Engineered Machine competition (iGEM 2005): Berkeley, Caltech, Cambridge, Davidson, ETH Zurich, Harvard, MIT, Oklahoma, Penn State, Princeton, Toronto, UCSF, and UT Austin. Learn about and sign up for the 2006 competition.

Photo of Davidson College students: Kristen DeCelle ’06 and Andrew Drysdale ’07. Davidson Students “Ace” Presentation at MIT Synthetic Biology Competition.

The Davidson team-“The Synth-Aces,” a word play on enzymes called synthases-presented their design of a genetically-engineered, E. coli-based “digital decoder.” The device detects which combination of three common chemicals (with eight combinations possible) is present, and then displays a human-readable number that glows in the dark. The number is produced by genetically customized bacteria that grow in a familiar pattern of a digital numeric display. The resulting readouts of “0” through “7” correspond to the specific chemical combination detected in solution. One real world application of a decoder device might be to monitor water for contaminants or toxins.

Bannanas Going Going Gone

Can This Fruit Be Saved? by Dan Koeppel, Popular Science:

The banana as we know it is on a crash course toward extinction. For scientists, the battle to resuscitate the world’s favorite fruit has begun…

. It also turns out that the 100 billion Cavendish bananas consumed annually worldwide are perfect from a genetic standpoint, every single one a duplicate of every other. It doesn’t matter if it comes from Honduras or Thailand, Jamaica or the Canary Islands—each Cavendish is an identical twin to one first found in Southeast Asia, brought to a Caribbean botanic garden in the early part of the 20th century, and put into commercial production about 50 years ago.

That sameness is the banana’s paradox. After 15,000 years of human cultivation, the banana is too perfect, lacking the genetic diversity that is key to species health. What can ail one banana can ail all. A fungus or bacterial disease that infects one plantation could march around the globe and destroy millions of bunches, leaving supermarket shelves empty.
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What can ail one banana can ail all. A fungus or bacterial disease that infects one plantation could march around the globe and destroy millions of bunches, leaving supermarket shelves empty.

A wild scenario? Not when you consider that there’s already been one banana apocalypse. Until the early 1960s, American cereal bowls and ice cream dishes were filled with the Gros Michel, a banana that was larger and, by all accounts, tastier than the fruit we now eat.

Scientists crack 40-year-old DNA puzzle

Scientist at University of Bath: Stefan Bagby, Jean van den Elsen and Huan-Lin Wu

Scientists crack 40-year-old DNA puzzle and point to ‘hot soup’ at the origin of life:

A new theory that explains why the language of our genes is more complex than it needs to be also suggests that the primordial soup where life began on earth was hot and not cold, as many scientists believe.
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The University of Bath researchers suggest that the primordial ‘doublet’ code was read in threes – but with only either the first two ‘prefix’ or last two ‘suffix’ pairs of bases being actively read.

The University of Bath researchers suggest that the primordial ‘doublet’ code was read in threes – but with only either the first two ‘prefix’ or last two ‘suffix’ pairs of bases being actively read.

By combining arrangements of these doublet codes together, the scientists can replicate the table of amino acids – explaining why some amino acids can be translated from groups of 2, 4 or 6 codons. They can also show how the groups of water loving (hydrophilic) and water-hating (hydrophobic) amino acids emerge naturally in the table, evolving from overlapping ‘prefix’ and ‘suffix’ codons.
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The theory also explains how the structure of the genetic code maximises error tolerance. For instance, ‘slippage’ in the translation process tends to produce another amino acid with the same characteristics, and explains why the DNA code is so good at maintaining its integrity.

“This is important because these kinds of mistakes can be fatal for an organism,” said Dr van den Elsen. “None of the older theories can explain how this error tolerant structure might have arisen.”