circadian rhythm tagged posts

For more than a year scientists investigated the development of six groups of mice in an outdoor enclosure. Credit: © MPI f. Ornithology

Mice with deviant internal rhythms due to a genetic mutation have fewer offspring and shorter life spans than normal conspecifics whose rhythms follow the 24hr cycle of a day more accurately. This discovery was made by a team of scientists led by researchers from the Max Planck Institute for Ornithology and Princeton University. Almost all living things possess internal clocks that govern periods of sleep and waking, and ensure these processes are in synchrony with night and day. This circadian clock evolved to allow the anticipation of regular daily events. Sunlight aligns the internal clock with the 24-hr-rhythm of the rotation of the earth.

Mutations ...

Examination of thousands of genes from nearly 150 human brains shows the circadian rhythm of gene activity changes with aging, according to a first-of-its-kind study conducted by researchers at the University of Pittsburgh School of Medicine. It suggest also that a novel biological clock begins ticking only in the older brain.

A 24hr circadian rhythm controls nearly all brain and body processes, such as the sleep/wake cycle, metabolism, alertness and cognition. These daily activity patterns are regulated by certain genes that are found in almost all cells, but have rarely been studied in the human brain. “Studies have reported that older adults tend to perform complex cognitive tasks better in the morning and get worse through the day,” Dr. McClung said...

Highlights •Timeless interacts with PARP-1 independent of poly(ADP-ribosyl)ation •Crystal structures of Timeless PAB in free form and in complex with PARP-1 •Specific recognition of PARP-1 by Timeless does not affect its enzymatic activity •PARP-1 is required for Timeless recruitment to DSB sites to promote HR repair

A new molecular mechanism for DNA repair involving an unexpected interaction between PARP-1 protein and sleep proteins in humans has been found. While it is a well-known fact that sleep is important to the body’s recovery and healing, knowledge of the molecular mechanisms that make this possible is incomplete...

Credit: Vera Kratochvil/public domain

Shifting Sleep Cycle affects Immune response, sleep quality. Ilia Karatsoreos, an assistant professor in WSU’s Department of Integrative Physiology and Neuroscience, shifted mice from their usual cycle of sleeping and waking and saw that, while they got enough sleep, it was of poorer quality. The animals also had a disrupted immune response, leaving them more open to illness.

Most sleep research focuses on the effects of sleep deprivation or the overall amount of sleep an animal needs. This is generally referred to as sleep’s homeostatic process, which is driven by sleepiness or “sleep pressure.”
“…disruption of the circadian clock is nearly ubiquitous in our modern society” due to nighttime lighting, shift work, jet lag and even the blue-tinged light ...