How can gene expression be changed by outside cues?

[Gauss44]

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I read that somewhere and cannot think of any examples.

(I wanted to say by a sun tan, but then thought that that's NOT changing the "expression" that's changing the appearance of skin AFTER genes have been expressed. Feel free to correct this if it is inaccurate.)

 

[echoyjeff222]

Eh? I'm a bit confused by your question, lol. If different genes are turned off or on after the sun tan, then isn't that "changing the expression" of the genes? The tanned skin is a result of the different gene expression... so I think the sun would count as an "outside cue" changing gene expression.

 

[2Pints]

I read that somewhere and cannot think of any examples.

(I wanted to say by a sun tan, but then thought that that's NOT changing the "expression" that's changing the appearance of skin AFTER genes have been expressed. Feel free to correct this if it is inaccurate.)

Are you talking about DNA methylation? With epigenetics?

http://www.nature.com/scitable/topicpage/the-role-of-methylation-in-gene-expression-1070

 

[Cawolf]

Mutations?

 

[Gauss44]

The points about genes being turned off and on and methylation are excellent points. Somehow, I was thinking of "outside" as meaning factors outside of the body. Maybe I've been studying too long today.

Edit: The point about mutations was added while I was writing this. I'll think about that after some rest.

Thanks all!

 

[Shirafune]

What about external factors inducing hormone release? For example, if you're stressed your adrenal cortex will produce cortisol and being a steroid hormone, plasma membranes are easily permeable to cortisol. Cortisol will bind intracellular receptors that eventually cause changes in gene expression. According to my physio professor, most hydrophobic signaling molecules like steroid hormones act to induce gene expression, rarely repress gene expression.

 

[Czarcasm]

I read that somewhere and cannot think of any examples.

(I wanted to say by a sun tan, but then thought that that's NOT changing the "expression" that's changing the appearance of skin AFTER genes have been expressed. Feel free to correct this if it is inaccurate.)

Lots of characteristics can be influenced by environment. There have been some studies on identical twins adopted in different environment - one more affluent than the other - nutritional and even social environments can play a role on growth and development. Children who grow with love and affection are likely to be more mentally developed and trusting of people. Hormones play an important role in this dynamic. These hormones indirectly effect genetic expression. Also, children who are obese develop more adipose cells which remain in adulthood. These kids are more prone to obesity and the effects that result including health abnormalities. I recall one study involving adipose hormone leptin (high amounts in obese kids) acts to stimulate GRH in the hypothalamus encouraging sexual maturity sooner than in those who are underweight. Height is another example. Some rabbits change fur color during temp changes. On a genetic level, things get more intricate so as you can imagine the whole Dyna!ic is very complicated. Ignore typos.used my phone