Peripheral clocks Flashcards
Which organs (besides the brain) have circadian clocks?
All of them
What was found when examining hamster retinal explants?
Melatonin was secreted rhythmically (even in DD)
Only explanation is that there is a timing mechanism in these cells
What was found about GFP:per expression in drosophila?
Rhythmic expression in all parts of the body
What happens when measuring per1:luc in peripheral explants?
Autonomous but not sustained rhythms were observed
How can fibroblasts be synchronized in culture? What happens if this is not done?
Serum shock promotes syncrhonous firing, otherwise all asynchronous
What was found about fibroblasts that was not seen in individual SCN cells?
Peripheral cells cannot form a tight cellular network
What was found when measuring Per1:luc expression in different tissue types after jet lag?
The SCN adjusted afte a week but peripheral clocks took much longer
How does the SCN communicate to peripheral clocks (to synchronize them or other)?
Body temperature
Feeding/fasting cycle
Nervous systems
Humoral systems
What did the parabiopsis experiment prove about peripheral clock entrainment?
One mouse with a SCN lesion and a wt mouse share a bloodstream
Before parabiopsis, the lesioned mouse did not have any variation in Per1 in liver and heart
After parabiopsis, the heart remained arhythmic but the liver clock was restored
This proves there was something in the blood that could rescue entrainment in the liver but not in the heart
How do glucocorticoids affect the central and peripheral clocks?
Central: No effect (SCN has no GC receptors)
Peripheral: Shifts in liver
What was found when measuring central and peripheral clocks during different feeding times?
SCN expression is independent of feeding, but reset the liver
What is the Cre-lox system?
What happened when Cre-lox was used to KO BMAL1 expression in
Retinas
Hepatocytes
Pancreatic cells
Cardiomyocyte (mutant CLOCK*)
Mating a mouse with LoxP domains around a gene with a mouse expressing Cre will produce offspring without that gene
Retinas: loss of circadian rhythm of electrical response to light
Hepatocytes: Altered glucose metabolism gene rhythms
Pancreatic cells: Higher glucose blood levels
Heart: Altered HR, BP, efficiency rhythms
