Gene expression (what's new?)

[Bill from WA]

This is really interesting. This sure isn't the Mendelian genetics we learned in school.

http://www.nature.com/nature/journal/v4 ... 07754.html

Bill

[Roger]

I read the article, but I don't pretend to say that I understood most of it. It seems to me that Mendel is still useful, but there are many reasons to explain why we don't get what we think we should. Tall peas will always give us Tall peas unless we breed a heterozyous Tall peas and short peas. Single trait inheritance is still pretty much the same. Am I close?

I wonder how this effects the idea that environment dictates the phenotypical outcome as much as the genetics effects it?

Much much too deep for me!!!!!!

[xfactor fan]

This may be the nuts and bolts that in part drives inbreeding depression.

There has been some observation that when chromosomes are doubled--identical chromosomes, for example the same chromosome 14 from the a horse in a pedigree, there are modifiers that line up and act like switches.

Two different modifiers = a plus condition, two identical modifiers = a minus condition.

The greater the number of doubled chromosomes, the greater the inbreeding depression.

[Linda_d]

This may be the nuts and bolts that in part drives inbreeding depression.

There has been some observation that when chromosomes are doubled--identical chromosomes, for example the same chromosome 14 from the a horse in a pedigree, there are modifiers that line up and act like switches.

Two different modifiers = a plus condition, two identical modifiers = a minus condition.

The greater the number of doubled chromosomes, the greater the inbreeding depression.

Can you explain what inbreeding depression means?

TIA.

[xfactor fan]

Well, it is the oposite of hybrid vigor. When a population get inbred, in addition to all sorts of recessives showing up, the population starts to show less variation, and may get smaller, weaker, less resistant to disease or climate change.

This in part is caused by animals with duplicate chromosomes. For example if Chromosome 14 has 6 different versions in a population, 14A, 14B, 14C, 14D, 14E, and 14F, a individual from a diverse population could have a pair of 14A, and 14E chromosomes. And while both the 14 chromosomes will have the same genes, they will have different versions of the gene.

Inbreeding increases the chances that the individual will carry two copies of the same chromosome for example 14A and 14A.


On the other hand, a very good inbred animal is likely to make a great breeder, as all of the bad genes have been bred out. Using the same example, lets say that chromosome 14C has lots of very good versions of the genes, so a individual that carries two copies of 14C can only pass on a 14C to their offspring.

When your good inbred animal is crossed with a different line, the inbreeding depression is reversed as the number of duplicate chromosomes is lowered.

One of the breeding theories out there is to inbreed for two generations then out cross.

Hope this helps, it is kind of complicated to try to explain.

[Linda_d]

Well, it is the oposite of hybrid vigor. When a population get inbred, in addition to all sorts of recessives showing up, the population starts to show less variation, and may get smaller, weaker, less resistant to disease or climate change.

This in part is caused by animals with duplicate chromosomes. For example if Chromosome 14 has 6 different versions in a population, 14A, 14B, 14C, 14D, 14E, and 14F, a individual from a diverse population could have a pair of 14A, and 14E chromosomes. And while both the 14 chromosomes will have the same genes, they will have different versions of the gene.

Inbreeding increases the chances that the individual will carry two copies of the same chromosome for example 14A and 14A.


On the other hand, a very good inbred animal is likely to make a great breeder, as all of the bad genes have been bred out. Using the same example, lets say that chromosome 14C has lots of very good versions of the genes, so a individual that carries two copies of 14C can only pass on a 14C to their offspring.

When your good inbred animal is crossed with a different line, the inbreeding depression is reversed as the number of duplicate chromosomes is lowered.

One of the breeding theories out there is to inbreed for two generations then out cross.

Hope this helps, it is kind of complicated to try to explain.

Thanks. I understand what you were trying to say, but I had just never heard the term "inbreeding depression".

[diomed]

There is also outbreeding depression.

[Bill from WA]

Hi xfactorfan.

Really well put. I wish I had been smart enough to get involved with genetic research at an early age instead of finding interest so late in life. What an incredibly fascinating time this is with all of the remarkable research taking place. Thank you Watson, Crick, Wilkins, Franklin, Pauling, et al.

Bill

[diomed]

I wish I had been smart enough to get involved with genetic research at an early age instead of finding interest so late in life.

Same here. I was interested when I was young however my mathematical handicaps got in the way. I am horrid at algebra and trig. My brain just doesn't compute. If it is explained visually, I get it.
I LOVED biology and totally got it. Chemistry was great until the algebra came along.

[Nessa]

Hi xfactorfan.

Really well put. I wish I had been smart enough to get involved with genetic research at an early age instead of finding interest so late in life. What an incredibly fascinating time this is with all of the remarkable research taking place. Thank you Watson, Crick, Wilkins, Franklin, Pauling, et al.

Bill

Actually Bill I think you've stepped into genetics at the right time. The things being found now, weren't even close to being known in the past.

[imnumberjuan]

In a facebook post I made prior to my first filly being born - I commented on how I had gone back on vow I had made after writing my Grade 12 biology exam that I would "never need that shit again"