What does expressed at a basal level mean?

[rockind78]

"expressed at a basal level"; used in reference to expression of the the human metallothionein gene.

Any thoughts would be most welcome. Thanks!

 

[iansmith]

It usually refer to a minimun of expression of a genes event though it is repressed. The lac operon is a good example. It is usually repressed under normal condition but you when you do rt-pcr you will find that some mRNA that encodes the for the lac operon but a minimun level.

 

[Monique]

So could you then say that 'at a basal level' means it is expressed at mRNA level, but not at the protein level?

 

[iansmith]

it is express at the protein level, the mRNA was just a way to show how you could detect it. IF the genes was totally repressed you would not find any mRNA.

 

[Monique]

Expression at protein level cannot be measured by detecting mRNA, those are not necessarily related. Repression is done by not translating the mRNA or degradation of the protein.

If transcription was repressed, you wouldn't see mRNA, true.

So rockind, were they talking about RNA or protein expression levels? Basal levels would be the level when expression is not induced :)

 

[rockind78]

Originally posted by Monique
So rockind, were they talking about RNA or protein expression levels? Basal levels would be the level when expression is not induced :)

Uh oh...It was a long night and I can't remember if that was the Alberts or the Lewin text. I'll get it posted in a little bit.

 

[rockind78]

OK. Found it...it was in the Lewin text, I have been using Alberts as a secondary source, they are both excellent. It looks to me like it is in the context of protein expression, but why don't you be the judge:

"The metallothionein (MT) gene provides an example of how a single gene may be regulated by many different circuits. The metallothionein protein protects the cell against excess concetrations of heavy metals, by binding the metal and removing it from the cell. The gene is expressed at the basal level, but is induced to greater levelsof expression by hevy metal ions (such as cadmium)or by glucocorticoids. The control region provides several different kinds of regulatory elements."

 

[Moonbear]

Originally posted by rockind78
OK. Found it...it was in the Lewin text, I have been using Alberts as a secondary source, they are both excellent. It looks to me like it is in the context of protein expression, but why don't you be the judge:

"The metallothionein (MT) gene provides an example of how a single gene may be regulated by many different circuits. The metallothionein protein protects the cell against excess concetrations of heavy metals, by binding the metal and removing it from the cell. The gene is expressed at the basal level, but is induced to greater levelsof expression by hevy metal ions (such as cadmium)or by glucocorticoids. The control region provides several different kinds of regulatory elements."

They seem to be referring to gene expression, not protein expression in this case, but either way, the term "basal level" means the same thing. It's the amount present under "baseline" conditions...in other words, if you don't do anything else to manipulate the system, you are measuring the basal, or lowest, level of something. So they are saying that if you do nothing else, there are very low but detectable levels of this gene expressed, and then they go on to further explain you get a change from this when you start adding other things to manipulate the system, such as adding heavy metal or glucocorticoids (those are hormones released in response to stress, generally). In this example, they are saying there is an increase in gene expression when these substances are added. Even though in normal English basal would mean lowest, in science, it usually refers to the undisturbed state, so you will see instances of something with expression reduced compared to basal levels in the presence of an inhibitor (with the above example, if you added something that shut off gene expression completely, you'd get such a scenario).