Mice deficient in the fragile X mental retardation 1 gene (FMR1) and a similar gene called fragile X-related gene 2 (FXR2) have no rhythm to their wake and sleep pattern, said Dr. David Nelson, professor of molecular and human genetics at BCM and co-director of the Interdepartmental Program in Cell and Molecular Biology.
Normal mice have a sleep-wake cycle of just under 12 hours awake and 12 hours asleep. Exposed to light and dark, they are awake in the dark and asleep during the light because they are nocturnal animals. If they are kept in the dark, their cycle reduces by about 10 minutes per sleep-wake period but remains fairly normal. When mice do not have either FMR1 or FXR2, they have a slightly shorter cycle but the difference is not dramatic.
"However, the double-mutants (those without both genes) have no rhythm at all," said Nelson. "This has never been seen in a mouse before." The animals, usually kept in a cage with a wheel on which they run when awake, sleep a little, run a little, sleep a little – but there is no rhythm to it.
The finding is important because parents whose children have autism or fragile X report problems getting their children to go to sleep and stay asleep. Fragile X is the most common known cause of autism. While there are few studies on the topic, said Nelson, "the impression I have is that many fragile X patients have a period of time that's like an extended infancy when they don't settle into a typical sleep–wake period."
Understanding how the gene associated with fragile X affect the circadian clock or the sleep-wake cycle could help explain some of the symptoms experienced by patients, he said.
After ruling out the possibility that the animals without the two genes could not perceive light, Nelson collaborated with a group in The Netherlands to test whether the cell's "central clock" called the suprachiasmatic nucleus in the animals was normal. They concluded that the clock was normal but that somehow the expression of genes that govern it is altered in these mice.
"These genes (FMR1 and FXR2) are new players in the control of circadian (daily) rhythms," said Nelson. Currently, the genes are thought to have a role in translating RNAs (ribonucleic acids) – particularly at the receiving side of the connections between neurons called dendrites. Dendrites are characterized by the fine branches that reach out into tissue. Scientists theorize that FMR1 and FXR2 may be involved in transporting the RNAs to the areas of those branches where the synapse is present.
Glenna Picton | EurekAlert!
Turning carbon dioxide into liquid fuel
06.08.2020 | DOE/Argonne National Laboratory
Tellurium makes the difference
06.08.2020 | Friedrich-Schiller-Universität Jena
Scientists at the Fraunhofer Institute for Laser Technology ILT have come up with a striking new addition to contact stamping technologies in the ERDF research project ScanCut. In collaboration with industry partners from North Rhine-Westphalia, the Aachen-based team of researchers developed a hybrid manufacturing process for the laser cutting of thin-walled metal strips. This new process makes it possible to fabricate even the tiniest details of contact parts in an eco-friendly, high-precision and efficient manner.
Plug connectors are tiny and, at first glance, unremarkable – yet modern vehicles would be unable to function without them. Several thousand plug connectors...
An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.
Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...
Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...
“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.
Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...
An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.
Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...
23.07.2020 | Event News
21.07.2020 | Event News
07.07.2020 | Event News
06.08.2020 | Earth Sciences
06.08.2020 | Power and Electrical Engineering
06.08.2020 | Life Sciences