Rhythm of the Night
Circadian rhythms, or cycles of activity during a 24 hour period, are highly conserved across species. While we have much to learn about these daily patterns of life, scientists have found an organism that may offer new insight.
The timing of this internal clock is related to the amount of exposure to light. How do circadian rhythms work in organisms that are not exposed to light? A Somalian cavefish, Phreatichthys andruzzii, is a blind species that has been living without light for approximately 1.4 to 2.6 million years!
Researchers compared the cave fish to zebrafish during exposures to 12 hour period of light followed by 12 hour period of dark. The cave fish remained active at irregular times while the zebrafish were active during exposure to light. Also, it was identified that in the zebrafish, genes associated with circadian rhythms were activated from exposure to light while the same genes in the cavefish were not.
In addition to light, these rhythms can also respond to other factors, including food. When scientists fed both types of fish at specific times for a month, they found that both fish were ready to eat at those times, demonstrating the circadian rhythms. Also, the genes associated with the rhythms were activated in both fish.
Photoreceptors are cells with specialized proteins that respond to light. While the genes associated with circadian rhythms in the cave fish were normal but not activated, it was found that genes for certain photoreceptors were mutated. The mutation caused important sections of the photoreceptors to be missing. After introducing functioning genes into cave fish, it appears that these transgenic fish could only respond to blue and green light. This tells us that there are photoreceptors for light that we do not know about!
|Print article||This entry was posted by Erin McKechnie on September 8, 2011 at 4:41 pm, and is filed under DNA From The Beginning. Follow any responses to this post through RSS 2.0. You can leave a response or trackback from your own site.|
No comments yet.
No trackbacks yet.
about 4 years ago - No comments
Lying dormant in our genomes are millions of jumping genes. Originally discovered by Barbara McClintock, transposons are DNA sequences that can move from one location to another in our DNA. Transposons cause mutations when they jump to new locations, so keeping them from jumping is important. However, although transposons are largely silent, every person probably…
about 5 years ago - No comments
For a very long time I have been using Diabetes as an example of a disorder that is caused by a mutation in the insulin gene. This mutation would stop the cells from making insulin, and a diabetic might need daily insulin injections to regulate their sugar levels properly. I don’t know what took me…
about 7 years ago - No comments
The instructions for life are carried in the DNA of our cells. All day long, our cells read the information in our DNA and make proteins. While DNA contains recipes for how life works, proteins are molecules that I consider the “doers” in our cells. Protein is a broad category that includes enzymes and hormones.…
about 7 years ago - No comments
Have you ever wished there were more hours in the day? I know someone who insists on extending his days by consuming energy drinks. In his opinion, sleeping is a waste of precious time. Unfortunately, for most humans, 8 hours of sleep is required to function properly. Some people can manage with far less sleep,…