Tag Archives: genetics

Location, location, location: how methylation relates to mutations

When it comes to mutations, location counts. Mutations, which are alterations to an organism’s DNA sequence, can have effects ranging from causing cancer to fueling evolution, depending on when and where they occur. And mutations don’t strike at random—they affect some regions of the genome many orders of magnitude more frequently than others. Of the
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Fruitless remains ever-fruitful: a genetic story of love and aggression

One of the most exciting prospects of biological inquiry lies in its potential to explain the peculiarities of our own lives. Human behavior provides some of the most spectacular examples of the output of a fundamentally biological system, the brain, but despite decades of remarkable research spanning the scale of neurotransmitters, to brain hemispheres, to interactions on the internet, we struggle to firmly explain the biological (and environmental) underpinnings of any given human behavior.

Luckily, some of our behaviors aren’t exclusive to our species. Chimpanzees seem to mourn the death of family members. Ants are capable of organizing into social hierarchies that eerily resemble human social structures.  Even the lowly fruit fly, Drosophila melanogaster, goes through bouts of light and heavy sleep that resemble human sleep cycles. All these examples suggest that the biology of behavior might be conserved in the same way that many genes are conserved from fly to human, and hint that perhaps the same genes control similar behaviors in wildly different organisms – a hint that tantalizes scientists to this day.

Thomas H. Morgan, the Nobel-prize-winning biologist who popularized the use of the fruit fly, D. melanogaster, as the model organism of choice for modern genetics, pictured in his Fly Room at Columbia University. <a href="http://www.nobelprize.org/nobel_prizes/medicine/laureates/1933/morgan-article.html"> Source </a>

A century ago, when the fruit fly was popularized as a model organism by the lab of Thomas Morgan, these similarities were fairly well-appreciated, but tools for manipulating fly genetics and observing fly behavior were lacking.  Fifty years later, researchers were better-prepared to manipulate the fruit fly genome, thanks to advances made in prior decades with mutating the fly genome with x-rays. In 1963, a researcher at Yale named Kulbir Gill used this technology to create mutant flies that lacked the typical behavioral program ensuring male pursuit of female partners for reproduction. These mutant male flies courted male and female partners equally, and utterly failed to reproduce. Gill dubbed this mutation ‘fruity,’ a less-than-appropriate pun on the fruit fly and its mating strategy, but limited his observations to a short note in a fly journal, declining to investigate further.
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Bdelloid Rotifers: Sex,Take 2

Isaac Newton, one of the most famous physicists to have ever existed, lived to be 84 years old and did so under a celibate promise. Imagine a lifetime without sex. Now imagine tens of millions of years without sex: meet the Bdelloid rotifers (Fig 1). These tiny, female-only metazoans (0.5 mm in length) are well-known for their asexuality and resilience toward desiccation and ionizing radiation. And while other animals like komodo dragons, stick-insects (Timema stick-insects have reproduced asexually for over 1 million generations!), and some sharks can asexually reproduce in response to the lack of viable males (in most cases), it’s incredibly rare to see an animal that reproduces asexually exclusively. Bdelloid (pronounced del●loi●d) rotifers are an “evolutionary scandal“, completely challenging the sexual reproduction dogma—that is, introducing genetic variation to allow species to adapt to their dynamic environments in addition to mitigating genetic degradation for the benefit of the population.

Not having sex isn’t what necessarily makes rotifers scandalous (bacteria don’t have sex and look at how well they’re doing), it’s that they’re complex multicellular organisms who have speciated to a degree similar to that of sexually reproducing organisms and who have done so asexually.
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Prop 37 debates continue: some Berkeley perspectives

The elections may be over, but the stream of debates continue: should genetically engineered (GE) food be labelled?

We’ll start with the facts—the easy ones. California Proposition 37, the California Right to Know Genetically Engineered Food Act, mandates the labeling of most food containing genetically modified ingredients. This includes raw or processed foods—but does not include food sold for immediate consumption, alcohol, certified organics, foods containing only small amounts of GE ingredients, food with the unintended inclusion of GE material, and non-GE animals fed or injected with GEs.  Of those who cast a ballot, 46.9% of Californians, 58.3% of Alameda County residents, and only 37.5% of UC Berkeley’s “Politics for Scientists” class supported the measure.  53.1% of Californians, 41.7% of Alameda County residents, and 62.5% of UC Berkeley’s “Politics for Scientists” class voted against mandated labeling of GEs.

The rest of the “facts” start to get hazy: GMOs are perfectly safe; GMOs are intrinsically bad. GMOs promote bad environmental practices; GMOs will save the environment while feeding the world. A vote for prop 37 is a vote against Monsanto and corporate monoculture; a vote for prop 37 is a vote against farmers, consumer grocery bills, and the state, which stand to lose up to 1 million for regulation. We have the right to know what’s in our food so that we may make educated choices; the broad label of GMO tells us nothing.
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