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Just Tell It Like It Is


Contributed by Sharon Bonnette, Ph.D.

Okay it’s been a month since daylight savings time took effect, and I think that just now my body is starting to get on schedule. My son is also finally getting used to the change, but at the beginning he was so confused with the concept, we had multiple conversations concerning the topic. Here’s one of them:


He says: “Mom, why is it earlier but later?”
My answer: “ ’Cause it’s later but earlier.” (huh?)
He says: “But what time is it really?”
I tell him: “It’s whatever time the clock “really” says it is.”


He keeps on (because this is the job of 7-year-olds, to keep asking the same question in hopes of getting a different not-so-smart-aleky answer):


“But why does it LOOK like I should still be playing outside, but YOU’RE telling me it’s time to bathe and get to bed?”


I say: “because maybe I’m trying to get you out of my hair.”


One day he’ll learn to not keep asking his mother the same question in hopes of getting the answer he wants, and exactly why it is so hard to get used to the whole daylight savings thing. But perhaps I should have just explained scientifically to him what is going on and why it seems “earlier but later” –HA! what a mess that would be, as it is I still have to explain the concept of time by relating it to the number of SpongeBob episodes that fit into an hour…


When we change the clocks ahead one hour in the spring it is a fact that it is not easy for the human body to physiologically adjust to the change, and the difference of only one hour truly has a great impact on our internal hard-wired biological clock or circadian rhythm. Many metabolic and physiological processes display circadian oscillations. Some scientists feel that forcing changes to our natural circadian rhythm could have lasting effects on our health and that disruption of these rhythms may be linked to obesity, diabetes, insomnia, depression, cardiovascular disease, and cancer (no wonder I feel like heck). A research group from UC Irvine has shown evidence that our metabolism is closely tuned with our circadian rhythm. In this study Nakahata et al. 1 show how the proteins CLOCK, SIRT1, and NAMPT/visfatin function together as part of the circadian clock. CLOCK functions as an acetyltransferase for histones and promotes circadian chromatin remodeling. SIRT1 functions as a deacetylase that counteracts the histone acetlytransferase activity of CLOCK. SIRT1 activity has been shown to be dependent on intracellular NAD+ levels. This led the group to investigate whether NAD+ levels oscillated with the circadian rhythm and whether NAMPT/visfatin, a critical enzyme in the NAD+ salvage pathway, was involved. Their results showed that CLOCK and SIRT1 regulate the expression of NAMPT/visfatin and are part of a circadian loop that links metabolism with the circadian clock.


So next time a 7-year-old asks you the why-is-it-earlier-but-later question, give them the easy answer and tell them that obviously their CLOCK, SIRT1, or NAMPt/visfatin proteins must be out of whack.


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Detection of human PBEF in FFPE fetal membrane by IHC.

Detection of human PBEF in FFPE fetal membrane by IHC.  Antibody: Rabbit anti-PBEF (IHC-00011). Secondary: HRP-conjugated goat anti-rabbit IgG (A120-501P). Substrate: DAB.

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Detection human TIPIN by WB of immunoprecipitates from HeLa lysate.  Antibodies: Rabbit anti-TIPIN (A301-473A and A301-474A). Secondary: ReliaBLOT® reagents (WB120).


1. Nakahata, Y., S. Sahar, G. Astarita, M. Kaluzova, and P. Sassone-Corsi. 2009. Circadian Control of the NAD+ Salvage Pathway by CLOCK-SIRT1. Science. May 2;324(5927):654-657.