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Jet&Copper
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07-10-2012, 04:15 PM
Originally Posted by Azz View Post
If you look at what I said - I said 'I think' and 'I guess' - it was not asserted as fact, and I'm also speaking in a broader sense (epigenetics *and* environmental) though I probably should have made that clearer.

Environmental factors do have an impact on gene related functions of our system - the gene responsible for the production of lactase is a great example. The gene is either in an on state, or off, but in some people it can switch between the two (I am living proof - having had a DNA test to clinically prove this - look up research by Dr Stephanie Matthews and Professor Anthony Campbell).

With regards to food, I'm suggesting that certain diseases such as cancer may not be primarily down to 'bad genes' that we inherit from our parents at birth, but rather, more attributable to environmental factors such as food, exposure to radiation, magnetic fields, toxic substances such as mercury etc. Again, I did not assert this as the final word on the matter (I don't suppose we will know 'for sure' for another few hundred to 1000 years to be honest) but merely my opinion based on personal knowledge and research (specifically of food) over the years - again I stress this is largely environmental, but epigenetic in the sense of how it can have an effect on some genes (such as the lactose example).
Ok, I took "I guess" to mean you had some background on the subject and weren't just making assumptions out of thin air, so was wondering what you had read or whatever. That said, let's understand that epigenetics is about changes that occur to the genome at a germline level and within the developing embryo - we are talking about modifications that an individual accumulates through their lifetime that may effect their offspring.

Environmental factors do not automatically go hand in hand with epigenetic modifications. Epigenetics refers very specifically to two main process that control chromatin remodelling - histone modifications and DNA methylation status.

Epigenetic control does not change the genes you were born with.

For a quick beginners guide, perhaps you would find Wiki useful?

http://en.wikipedia.org/wiki/Epigenetics

The lactase gene you talk of (I'm guessing you have Asian parentage?) - this is not an example of epigenetic control, it's simply down to SNP's (genetic polymorphisms) within a population? Unless I'm thinking of something else? In what way has environmental effects in your lifetime caused this? You would have been born with it?

Finally - yes and no. Cancer is a very complicated subject and yes environment factors play a role, such a exposure to carcinogenic compounds giving rise to cancers. However, if I was exposed to a carcinogen, and then developed cancer due to a somatic cell mutation, this has absolutely nothing at all to do with epigenetics but everything to do with environment. The terms "epigenetics" and "environmental effects on genes" are not the same and are not interchangable - make sense?

This of course is purely my opinion based on the fact that I study this stuff for a living and hold a PhD in the subject. teehee
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bijou
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07-10-2012, 05:23 PM
Therefore, if you outcross to the general population, you will see the dominant "healthy" gene take over in the original population and we begin to lose the mutation in terms of frequency -

perhaps in terms of frequency but is it not also true that by outcrossing we run the risk of introducing a delterious gene to a previously unaffected population ...
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07-10-2012, 05:28 PM
Therefore, if you outcross to the general population, you will see the dominant "healthy" gene take over in the original population and we begin to lose the mutation in terms of frequency -

perhaps in terms of frequency in the original affected population but is it not also true that by outcrossing we run the risk of introducing a delterious gene to a previously unaffected population ...
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Jet&Copper
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07-10-2012, 05:31 PM
Originally Posted by bijou View Post
perhaps in terms of frequency but is it not also true that by outcrossing we run the risk of introducing a delterious gene to a previously unaffected population ...
Yes, absolutely Bijou. This is why we need to talk specific examples and not as mass generalisations.

This would be entirely dependent on, for example, the transmission method of the specific gene, is it inherited in a dominant or recessive fashion, or otherwise, is it X-linked.....we need to question penetrence, signalling pathways involved, linkage, other gene effects on expression, the list goes on. OF course is the mutation somatic? Etc etc etc!

So many variables and absolutely why we cannot make sweeping statements like crossbreeds are healthier than pedigrees or vice versa. Inbreeding depression is just but one example I was explaining for genetic fitness - it is in no way whatsoever the be all and end all of the story.

All we can do is make comparisons between specific populations or, specific individuals.

Glad we are on the same wavelength here.
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07-10-2012, 05:55 PM
ahh ...but meanwhile decisions about breeding need to be made and the practicalities are that it is safer to breed with what you know about your breed and your lines - for example the bitch I'm planning to breed next has a dog in her pedigree that if doubled up on may produce monorchidism ...there appears to be no epilepsy, good hips and eyes, great temperaments and excellent construction and type, so I only need to focus on looking for a stud dog that always produces entire males...simples !

However if I outcrossed to a different breed whose background and lines I did not know as much about I am effectively working 'blind'...why would I run the risk of introducing problems into my lines that are not currently there ?

Yours is the theory ...mine is the reality....
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Jet&Copper
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07-10-2012, 05:59 PM
Originally Posted by bijou View Post
ahh ...but meanwhile decisions about breeding need to be made and the practicalities are that it is safer to breed with what you knowabout your breed and your lines - for example the bitch I'm planning to breed next has a dog in her pedigree that if doubled up on may produce monorchidism ...there appears to be no epilepsy, good hips and eyes, great temperaments and excellent construction and type, so I only need to focus on looking for a stud dog that always produces entire males...simples !

However if I outcrossed to a different breed whose background and lines I did not know as much about I am effectively working 'blind'...why would I run the risk of introducing problems into my lines that are not currently there ?

Yours is the theory ...mine is the reality....
No need to say "aaahhh" like you have somehow caught me out - rather rude tbh

Where do I say that breeders should not keep breeding?

Mine is also reality, in fact im pretty sure i have already cited quite a number of real life examples have i not?

I see this went downhill quick *sigh*
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Azz
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07-10-2012, 06:08 PM
Originally Posted by Jet&Copper View Post
Ok, I took "I guess" to mean you had some background on the subject and weren't just making assumptions out of thin air, so was wondering what you had read or whatever. That said, let's understand that epigenetics is about changes that occur to the genome at a germline level and within the developing embryo - we are talking about modifications that an individual accumulates through their lifetime that may effect their offspring.

Environmental factors do not automatically go hand in hand with epigenetic modifications. Epigenetics refers very specifically to two main process that control chromatin remodelling - histone modifications and DNA methylation status.

Epigenetic control does not change the genes you were born with.

For a quick beginners guide, perhaps you would find Wiki useful?

http://en.wikipedia.org/wiki/Epigenetics

The lactase gene you talk of (I'm guessing you have Asian parentage?) - this is not an example of epigenetic control, it's simply down to SNP's (genetic polymorphisms) within a population? Unless I'm thinking of something else? In what way has environmental effects in your lifetime caused this? You would have been born with it?

Finally - yes and no. Cancer is a very complicated subject and yes environment factors play a role, such a exposure to carcinogenic compounds giving rise to cancers. However, if I was exposed to a carcinogen, and then developed cancer due to a somatic cell mutation, this has absolutely nothing at all to do with epigenetics but everything to do with environment. The terms "epigenetics" and "environmental effects on genes" are not the same and are not interchangable - make sense?

This of course is purely my opinion based on the fact that I study this stuff for a living and hold a PhD in the subject. teehee
I wonder if you realise how rude you come across sometimes?

Anyway... environmental factors do have an impact on your epigenome (that's what Epigenetics is all about):

At its most basic, epigenetics is the study of changes in gene activity that do not involve alterations to the genetic code but still get passed down to at least one successive generation. These patterns of gene expression are governed by the cellular material — the epigenome — that sits on top of the genome, just outside it (hence the prefix epi-, which means above). It is these epigenetic "marks" that tell your genes to switch on or off, to speak loudly or whisper.
Epigenetics brings both good news and bad. Bad news first: there's evidence that lifestyle choices like smoking and eating too much can change the epigenetic marks atop your DNA in ways that cause the genes for obesity to express themselves too strongly and the genes for longevity to express themselves too weakly.
http://www.time.com/time/magazine/ar...2313-2,00.html

Perhaps I was speaking a bit too broadly in my original post.

My own personal viewpoint is that environmental factors do and can dictate matters of health where sometimes 'bad' genes can be attributed as a cause (such as cancer).
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Jet&Copper
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07-10-2012, 06:10 PM
What exactly did i say that was rude?
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Azz
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07-10-2012, 06:16 PM
Originally Posted by Jet&Copper View Post
What exactly did i say that was rude?
Your first sentence. Not really in the spirit of amicable discussion imo.
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Jet&Copper
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07-10-2012, 06:20 PM
Originally Posted by Azz View Post
Your first sentence. Not really in the spirit of amicable discussion imo.
Where i explained my mistake in interpreting the wording of your post? It certainly wasn't meant to sound rude - it was an explanation of why i replied asking you for information.

I think you are being rather over-sensitive, but in any case i apologise if you feel that way, it's certainly not intentional i assure you.
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