Dear visitor (if there is any) please note the following: The blog "Broken Radius" is hosted at Google Blogger's server. I can therefore not guarantee that your visit to the blog or any comment you write wont be recorded by the NSA. If you have any worries about this, you can visit instead my alternative blog Letters-to-a-Persian-Cat. This one is hosted at a European server which hopefully acknowledges visitors privacy.


Sun-Light and Skin Tanning

Ghazal my dear,

Hope you arrived well in Unterschleissheim. Just for your interest, and maybe to be used for your PhD project in Stockholm on UV-radiobiology, I found a nice review article explaining how UV-exposure upregulates pigmentation through tanning.
What seems to be essential are the UV induced Thymin-Dimers on the DNA of keratinocytes. Through P53 (as usual), pro-opiomelanocortin (POMC) is expressed and quickly converted into a-Msh (Melanocyte stimulating hormone). This is released from keratinocytes and binds to a Melanocortin1-Receptor (Mc1r) on melanocytes. They, in turn increase the production of Eumelanin (the brown-blackish pigment characteristic for tan). The only thing I still don"t understand is why a P53 response after ionising radiation causes other cellular effects (like cell-cycle block or apoptosis) than after UV-damage ? Somewhere, there must be a specific pathway.
What is very interesting, it was shown that treating skin simply with thymidin-rich DNA induces tanning itself (without the detrimental side effects of a UV exposure). But to be honest, I don"t understand the desire of people to get tanned at all. It looks much more aristocratic beeing pale, don"t you think so.

Are you going to watch the Insomnia movie tonight ? I remember it is a rather slow movie, with long camera settings and nice pictures.
Absolute the oposite to yesterdays action film. I"m afraid you might fall asleep, since it is so slow and tranquil. Would be an absurd thing, if you fall asleep during a movie that is about sleepness.

You know what is funny: Your ex-watch (now it is mine, o.k.) runs on the second since you gave it to me. I just contemplate whether it would be possible to permanently link the two watches with each other by a "telepathic extrasensual connector" (sounds to technical to you, my dear ?).
Have a look at this artikel on a phenomenon called Quantum Entanglement. If this works (what I hope) we could stay connected even over long distances by wearing the same watch at the same time. I agree that sounds weared, sounds like a plot for a movie even more weared than the one from yesterday. I don"t want to cause you headache, my dear. Just sometimes my phantasy goes wild. To be honest, I just want to keep the watch as a memory.

Enjoy the evening

Take Care


hi michael!

thank you for the article. so interesting, so the thymidine dimers gives the tanning. so strange. yes, why does p53 react differently with ionisin radiation and uv-light. well they give different dna-damages. so that is probably how it recognize how to react. but why it reacts differently is a mystery. :) it looks nice to be tanned, on some people. i think i look best when im tanned. but i dont mind being pale. both is nice.

i dont think i will watch the insomnia movie. i just woke up. but i will save the movie for the week-end maybe. i bought two sauerkraut (think its called). i ate one whole package today! it is so nice. they still dont know which car i will get. but he said that 99% audi a3. i would be soooo happy if that is the car. so just have to hope until wednseday.

the thing with the watch seems very complicated! my watch works on the second right now. but maybe it needs time to slow down, we will see.

have a good evening.


Ghazal my Dear,

Maybe you are right that P53 can sense differences between the various types of DNA damage (strand-breaks vs. Thymidine-Dimers). P53 has a whole range of different peptides, that can all be phophorylated or otherwise activated. In theory, this could than (in response to different types of DNA damage) also transactivate different target genes (for instance P21 after IR and POMC after UV). But to my knowledge, this is yet speculative. You see, still many exiting things to discover for you (I think I don"t have to repeat how much I"d like to convince you to stay here for a PhD).

About tanning: In addition to the accelerated skin aging, I prefer pale skin from an aesthetic point of view. In your case, it most attractively contrasts with your dark hair. Stay as you are, Ghazal. There is nothing in you to improve, honestly.

When I brought you home yesterday night you asked about the different phrases used in Germany to say good-bye. I hope, this was just a general linguistic interest, rather than the feeling that you have to prepare for a farewell from here. Please, no unneccessary thoughts.
Just for your "scientific interest": the most offical "Auf Wiedersehen" is very nice in this sense, since it implies not a long, but only a temporal absence. You translated it quite right yesterday with "See you again soon".
"Tschau" comes from the italian "Ciao", short for "Arrivederci". I guess that the german "Tschuess" is derived from "Ciao", but is mainly used in the north and it is rather neutral and un-personal. You can say "Tschuess" if you leave a Shop. What is a special south-german / austrian phrase is "Servus", which comes from "to serve" and means "I will serve you". It is used both as a greeting as well as for farewell. Sometimes used in literature with a slightly melancholic connotation (for a sad farewell).
The english / swedish "Farewell" means something for ever, I think. It originally means "Happy Journey" or so, from the old-german "Fahre wohl". I hope we"ll never have to use such a terminal phrase, my dear.

Sleep well, dream well, smile, if you want (good luck with the Audi A3)

Take Care,


No comments:

Post a Comment