Wednesday, December 9, 2015
Of Course Biology Exhibits Engineering Principles
Just as every human-designed system must conform to standard engineering principles — discovered by trial and error — in order to work efficiently, so must biological systems at all levels be replete with engineering principles in order to maintain proper fitness.
Thursday, November 12, 2015
Why are fruit fly gene names so weird?
My lab studies the fruit fly (Drosophila melanogaster), which is one of the most well-studied animal systems. Historically, fruit flies have been studied because the genetics is very easy. Early on, the way to study genetics was to cause the flies to become mutated (altering their DNA randomly), and then see what happened. Well, some pretty funky things happened.
Sometimes, the resulting flies looked all bristly -- researchers named that mutation "hedgehog". Sometimes, they looked like a tube -- researchers called that mutation, well, "tube". And so, names like "armadillo", "wingless", "cactus", "pipe", and "dachshund" were born.
Later, scientists found that these mutations mapped to genes within the flies' DNA. Naturally, these genes were named after the mutation that the researchers originally found.
It turns out that one of the first mutations geneticists worked with was a spontaneous mutation that they named "white". Well, guess what this mutation did? It turned the turned the flies' eyes from red to white. So when the genes were later named for the mutation involved in their discovery, the gene responsible for turning the flies' eyes red was called "white". Brilliant!
So this is why many genes in the fly genome are named backwards.
Sometimes, the resulting flies looked all bristly -- researchers named that mutation "hedgehog". Sometimes, they looked like a tube -- researchers called that mutation, well, "tube". And so, names like "armadillo", "wingless", "cactus", "pipe", and "dachshund" were born.
Later, scientists found that these mutations mapped to genes within the flies' DNA. Naturally, these genes were named after the mutation that the researchers originally found.
It turns out that one of the first mutations geneticists worked with was a spontaneous mutation that they named "white". Well, guess what this mutation did? It turned the turned the flies' eyes from red to white. So when the genes were later named for the mutation involved in their discovery, the gene responsible for turning the flies' eyes red was called "white". Brilliant!
So this is why many genes in the fly genome are named backwards.
Wednesday, October 28, 2015
How do cells know what to do in an embryo?
One of the biggest questions that has been on the minds of biologists is how are tissues patterned? In other words, how do cells make decisions in a developing embryo? How does a cell know to become skin rather than muscle? Or stomach lining rather than bone marrow?
The general answer (although the details are still being worked out) is called the "morophogen gradient model".
A morphogen, or a protein or other small molecule, serves as a signal to tell cells what to do. Imagine a bunch of cells in a sheet that will eventually become part of a tissue. Each of these cells will become something different from their neighbors, but initially, they are all the same.
At one end of this sheet of cells, a set of cells (blue in the figure) produces a secreted protein (the morphogen) that diffuses through the extracellular space next to the cells. The cells capture the morphogen. As the morphogen gets further away from the cells that produced it, the concentration of the morphogen decreases (brown curve in the figure).
One might think of the cells that produce the morphogen as a cell phone tower, and the further away one gets, the less signal one would perceive. And the cells then respond depending on how much morphogen they perceive (white, red, and gray in the figure). So two cells next to each other will perceive different amounts of signal (morphogen), and they will know to do different things. One might become a neuron, while the other a skin cell.
In this way, a single signal, in the form of a secreted protein called a morphogen, can pattern an entire tissue.
The general answer (although the details are still being worked out) is called the "morophogen gradient model".
A morphogen, or a protein or other small molecule, serves as a signal to tell cells what to do. Imagine a bunch of cells in a sheet that will eventually become part of a tissue. Each of these cells will become something different from their neighbors, but initially, they are all the same.
At one end of this sheet of cells, a set of cells (blue in the figure) produces a secreted protein (the morphogen) that diffuses through the extracellular space next to the cells. The cells capture the morphogen. As the morphogen gets further away from the cells that produced it, the concentration of the morphogen decreases (brown curve in the figure).
One might think of the cells that produce the morphogen as a cell phone tower, and the further away one gets, the less signal one would perceive. And the cells then respond depending on how much morphogen they perceive (white, red, and gray in the figure). So two cells next to each other will perceive different amounts of signal (morphogen), and they will know to do different things. One might become a neuron, while the other a skin cell.
In this way, a single signal, in the form of a secreted protein called a morphogen, can pattern an entire tissue.
Monday, October 26, 2015
If we can expect engineering principles in biology...
If biology is rife with engineering principles, then why not use that as a predictive tool?
Thursday, October 8, 2015
Engineering principles are everywhere!
One of the observations that scientists have made about biology is that is it rife with engineering principles. But of course we should expect such a thing. Any man-made structure that we build would surely fail unless it is in accord with good engineering principles. Why should anything less be expected of living systems?
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