On Sat, 7 Feb 2004 05:52:56 +0000 (UTC), cncabej{at}aol.com (CNCabej)
wrote:

>On  Fri, 6 Feb 2004 16:36:06 +0000 (UTC)
>
>Tim Tyler wrote:>> >Kola9809  wrote:
>>
>>> >> Pineal gland cells produce melatonin in response to
day-night cycles.
>>The
>>> >> generally accepted mechanism is that the photic
stimuli (which do not
>>> >> per se activate any gene) are received in retinal
neurons, converted 
>>> >> into electrical signals that are processed (and alternatively 
>>> >> transformed into chemical-electrical signals) in a
neural circuit 
>>> >> involving neurons of the superior cervical ganglion, 
>>> >> intermediolateral nucleus of the upper thoracal spinal cord, 
>>> >> hypothalamic paraventricular nucleus, suprachiasmatic nucleus,
>>> >> until it reaches the pineal gland cells where the
chemical output of
>>> >> the circuit activates genes involved in the synthesis
of melatonin. 
>>> >> 
>>> >> My question is: Since the activation of those genes
is not a random 
>>> >> process, it requires information. Where does that
information come from?
>>> >
>>> >>From the environment.
>>> 
>>> If that information is the environmental stimulus (which you
seem to imply)
>>> skin cells that are in direct contact with it would produce melatonin as
>>well.
>>> But, as you know, they can not while pineal cells with the same set of
>>genes,
>>> do? And the reason is that only (!) pineal cells receive the
information on
>>the
>>> stimulus (but not the stimulus itself).
>>>   
>>> Nevertheless, you may be be right and I - wrong. But, could
you elaborate.
>>> 
>>> As all we know, the  pineal cells do not receive the stimulus (day-night
>>> cycles); they are invariably in darkness. That stimulus is received by
>>retinal
>>> neurons (they, nevertheless do not produce melatonin), which
code it in the
>>> form of specific electrical signals (this is the information
on the nature
>>of
>>> the stimulus). But this information still is not
"intelligible" to genes.
>>This
>>> is why  it is  once more processed in the complex melatonin 
circuit, which
>>> releases a chemical signal that via signal transduction pathways affects
>>the
>>> expression of genes responsible for melatonin synthesis in pineal cells.
>>> 
>>> I'm openminded to listen and change my opinion.
>>
>>This is like me saying that your friend's voice on the telephone
>>comes from your friend - and then you arguing that it is actually
>>coming from the speaker in the telephone handset.
>>-- 
>
>Let's get serious. I am very interested in  discussing this topic. Do you
>really think that information from the environment regulates the function of
>our genes ? 
>
>If information implies a sender and a receiver, do you believe that the
>environment is the sender and genes are the receivers of environmental
>information?
>Can you substantiate this Lamarckian concept?
>
>As I have pointed out earlier, I see this differently. A piece of information
>from the environment would be used by genes only if it is
"intelligible" to
>them, but the circadian cycle (the sun light or the lack of it) is not. Neither
>the sun light nor the darkness are able to activate/inactivate any gene. This
>is the reason why the stimulus is received and converted into an electrical
>signal (=information) and further processed in the melatonin neural circuit
>which generates the chemical signal (=information) that is intelligible to the
>gene as the "receiver". It is not the external stimulus per se, but the
>chemical output (=information) generated by  processing of the stimulus in the
>neural circuit that via the respective transduction pathways reaches the genes
>responsible for the synthesis of melatonin, that is intelligible to (i.e.
>contains information for) activating those genes. This information generated in
>the neural circuit is processing-dependent, hence epigenetic; it does not exist
>but it is computationally generated in response to external/internal stimuli.
> 
>Let me try an analogy from linguistics (my hobby). When I spell the Messapian
>(an ancient indoeuropean language spoken in southern Italy more than 2 thousand
>years ago) word "bila" it conveys no information to you as a
receiver, although
>it did for the Messapians. Now, I make it intelligible to you by translating it
>into the English word "daughter". Similarly, the neural
circuits "translate"
>the external stimulus, which is "senseless" to genes, into a specific
>epigenetic information for their activation/inactivation.
>
>Do you agree? 
>I wait for your input.
>

I still think that "information translation" is not a proper way of
looking at the situation.

Light entering the eye causes genes to be expressed in specific cells.
There are a lot of intermediate steps, but there is a demonstrable
chain of cause-and-effect events that can be described linking
stimulus to response.  It is not necessary to talk in terms of
information generation, merely in terms of "event A causes event B
causes event C causes event D causes ..... causes event Z. Light in a
rod or cone cell is translated into electrical potential, but that
involves a whole series of intermediate steps.  Changes in electrical
potential in rod and cone cells in the retina cause release of
synaptic transmitter onto melatonin secreting cells in the pineal, but
that involves a whole series of intermediate steps.  Synaptic
transmitter binding to receptors on melatonin secreting cells in the
pineal activate genes in the cell nucleus, but that involves a whole
series of intermediate steps.

The problem is one of cell physiology, not of information translation.
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