Many grad students can sympathize with the blind form of Astyanax mexicanus. Scholars speculate that they only a few hours a night, sleep, because they not simply to rest.
"These fish live in an environment where food is generally scarce, and present episodic and unpredictable," said Richard Borowsky of New York University in a press release from the school. "If you asleep food are a bit of hovering, you are out of luck and a meal."
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Borowsky and his colleagues, Erik Duboué and Alex Keene, discovered that sightless form of Astyanax mexicanus (Mexican Mexicanus) needed far less sleep as his sighted related fellows. Their observation of fish in the dark can shed light on human sleep disorders.
"In a sense the sleep phenotypes cave fish of people with sleep disorders, are similar to," explained Borowsky. "they go to sleep, but only for relatively short, then they wake up and stay awake for a relatively long period of time."
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"The next individual operation is to identify the genes that change in the cave fish are responsible for sleep." "You good candidates for the genes for insomnia and other sleep disorders in humans would be responsible," said Borowsky.
The researchers noticed first while working on a study looking back in the blind form of fish to breed the Tetra's sleeping habits.
In a study in 2008 in current biology scientists was published, that if it crosses blind populations of various caves in Northeast Mexico, the fish eyes in only one generation work regained. This happened because the different populations have developed independently of the other blindness. Different genetic changes blindness in each population causes, so that if the fish have been crossed, offspring was partially restored to see the ability in their.
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In the course of this study, the scientists noticed that the blind Tetra's less inactive below their aquariums were time at night as their sighted related issues.
To determine whether what they see, were is a real difference in the sleep pattern was, the researchers two methods used. One was, wait until the fish were inactive, then type for your aquarium and see if she slow reacting. A slow response meant a sleepy fish.
The other was to deprive the fish to see sleep for a whole night, as they responded the next day. When she took many NAP on the next day, they were interpreted as deprived of sleep.
The sighted fish responded to this torment over her blind cousins.
The researchers found that over a period of 24 hours, sighted fish on average more than 800 minutes (13 hours slept) slept during blind fish on average 110 to 250 minutes.
Try their observations the researchers crossed even further, then the fish. She found that, like blindness, insomnia genetic. The hybrid fish sleep disorders, such as parents were blind. This led the researchers to the conclusion that it was a dominant gene, caused insomnia.
The blind fish were of different population groups. They came from three unrelated Mexican cave systems, Pachón, Tinaja and Molino. This is an indication that the fish of the same evolutionary conclusion to a problem arrived by separate genetic ways, a phenomenon known as convergent evolution.
"We a cave associated with phenotype unsuspected until documented now, be that have the basic adaptation of aquatic vertebrates cave entrance could be life," Borowsky said.
Another experiment on the researchers list is exactly what evolutionary forces drove the biological convergence of the different Tetra populations found.
The results from the fish sleep experiment were published in the journal current biology.
Figure 1: Blind and sighted forms of Astyanax mexicanus (courtesy: NYU Press release)
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