Tag Archives: genes

ScienceMatters@Berkeley April 2007

As usually the latest issue of ScienceMatters@Berkeley includes several intersting articles including, The Protein Machine by Kathleen M. Wong

A large percentage of known antibiotics target bacterial ribosomes, including tetracycline, erythromycin, and streptomycin. Many of these antibiotics have been isolated from microbes themselves. “It’s a byproduct of the chemical warfare that’s been going on among bacteria for hundreds of millions of years,” Cate says. “We want to understand how these natural products inhibit translation. Then, based on what we understand about the ribosome mechanism, we should be able to come up with new ways to stop bacterial translation based on the old compounds.”

Self-Tuning Genes:

Researchers such as UC Berkeley’s Adam Arkin have found that regulatory feedback is associated with chance fluctuations in mRNA or protein levels—a phenomenon called expression noise. “Even though they’re all genetically identical, and grown under the same conditions, yeast clones don’t express certain proteins at exactly the same level,” Brem says. “Some genes are noisier than others. That makes people think the cell is actively tuning the distribution around an expression level set by the regulatory network.” Noise may ensure that a few individuals can handle abrupt changes in their environment. In other words, if a colony is suddenly assaulted by toxic chemicals or high heat, a few individuals will already have expression levels suited to those conditions.

Bdelloid Rotifers Abandoned Sex 100 Million Years Ago

Who Needs Sex (or Males) Anyway? by Liza Gross:

If you own a birdbath, chances are you’re hosting one of evolutionary biology’s most puzzling enigmas: bdelloid rotifers. These microscopic invertebrates—widely distributed in mosses, creeks, ponds, and other freshwater repositories—abandoned sex perhaps 100 million years ago, yet have apparently diverged into nearly 400 species. Bdelloids (the “b” is silent) reproduce through parthenogenesis, which generates offspring with essentially the same genome as their mother from unfertilized eggs.

Scientists stumped by 100m years of chastity

Bdelloid rotifers are egg laying microscopic invertebrates — widely distributed in mosses, streams and ponds — which have managed to diverge into nearly 400 species without a scintilla of sex… Now a new study, published today in the journal PLoS biology, has confirmed the worst fears of scientists: the rotifers do indeed present a major challenge to the assumption that sex is necessary for organisms to diversify into species.
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Rather than mixing up DNA, creatures like the bdelloid rotifers can evolve solely through the build-up of mutations that occur in the ‘cloning’ process when a new rotifer is born. The new study proves that these differences are not random and can help rotifers adapt to a different environment, such as the legs or chest of a water louse. Bdelloids can be found happily swimming around in a puddle in your garden, hot springs or in freezing ponds in the Antarctic.

DNA Offers New Insight Concerning Cat Evolution

DNA Offers New Insight Concerning Cat Evolution, Nicholas Wade, New York Times:

Before DNA, taxonomists had considerable difficulty in classifying the cat family. The fossil record was sparse and many of the skulls lacked distinctiveness. One scheme divided the family into Big Cats and Little Cats. Then, in 1997, Dr. Johnson and Dr. O’Brien said they thought most living cats fell into one of eight lineages, based on the genetic element known as mitochondrial DNA.

Having made further DNA analyses, the researchers have drawn a full family tree that assigns every cat species to one of the lineages. They have also integrated their tree, which is based solely on changes in DNA, with the fossil record. The fossils, which are securely dated, allow dates to be assigned to each fork in the genetic family tree.
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The leopard lineage appeared around 6.5 million years ago in Asia. The youngest of the eight lineages, which led eventually to the domestic cat, emerged some 6.2 million years ago in Asia and Africa, either from ancestors that had never left Asia or more probably from North American cats that had trekked back across the Bering land bridge.

Photos from Curious Cat Travel Photos – Kenya

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.

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.