Genetics ?? Hypo gene specifically

[crotalusadamanteus]

Well, I admit that I have not used words like "phenotype, genotype, alelle, and loci" since high school. Boa genetics were explained to me in simple "english". Never in a manner such as this. But I don't mind, it's actually pretty interesting. And a good explanation of how the gene works.
I know that homozygous is "Having the same alleles at a particular gene locus on homologous chromosomes." Usually expressed correct?
I know that heterozygous is "Having different alleles at one or more corresponding chromosomal loci." Not expressed usually, correct?
And I do pretty much understand what you are saying. And believe it or not, it does make some amount of sense to me. It just has to sink in. LOL
I think I'm stuck more on the "proof" stuff. It's easier to believe what you see. And I have not seen a normal, from a litter of salmon, produce anything but normals. Than again, I have not had years of morph breeding experience. I rely on the info I have obtained from people that HAVE done it for a while. Perhaps I got lost on the explanations given.

I also will read the suggested " Mendel" and his pea plants. (No body knows so much, that they can't learn more, right?). Maybe it will help me to "better understand" as you put it.

M.Dwight.........Just curious why the "12" yr old off to the left? Sorta misleading don't you think? I had my doubts as to the age once i read your first post. Not spoken like most 12 yr olds. LOL

 

[Serpwidgets]

I think I'm stuck more on the "proof" stuff. It's easier to believe what you see. And I have not seen a normal, from a litter of salmon, produce anything but normals. Than again, I have not had years of morph breeding experience. I rely on the info I have obtained from people that HAVE done it for a while. Perhaps I got lost on the explanations given.

This is because a normal is not carrying any copies of the Salmon mutant. If it were, the snake would not be a normal. The only way a normal "sibling to salmon" would have salmon offspring is if its mate were carrying the mutant gene.

When you cross a salmon to a normal and get normals and salmons, it all makes sense when you look at what is happening underneath the hood... the normal is S⁺·S⁺ (homozygous normal) and the salmon is S⁺·S^S (heterozygous normal and salmon) and the Punnett square for this cross reflects the results you expect:

<table border=1><tr align=right><td> </td><td>S⁺</td></tr>
<tr><td>S⁺</td><td>S⁺·S⁺</td></tr><tr><td>S^S</td><td>S^S·S⁺</td></tr></table>

The normal (on top) is giving the wild-type allele to all offspring, the salmon (on the left) is heterozygous and thus giving the wild-type to some, the salmon mutant to others. The resulting genotypes in the litter are normal (homozygous or genotype S⁺·S⁺) and the salmons are hets (S⁺·S^S)

Obviously a normal will not throw the salmon mutant to any of its offspring, because it does not have a salmon mutant to give. Nobody is saying that a normal is het for salmon. But a salmon is het for salmon and wild-type at the salmon locus, the same as a "normal het for albino" is a normal het for albino and wild-type at the albino locus. What is being called a "super salmon" is simply homozygous for the salmon mutant at the salmon locus.

 

[M.Dwight]

M.Dwight.........Just curious why the "12" yr old off to the left? Sorta misleading don't you think? I had my doubts as to the age once i read your first post. Not spoken like most 12 yr olds. LOL

Sorry about that. That developed as part of an inside joke while in the chat room. And I forgot to change it back. I'll get to it however.

 

[M.Dwight]

Charles, as always your post are right on the money. You should stop by here more often. The folks here seem to need your knowledge.
I have a fairly advanded grasp on genetics and cell biology right down to the nuclear level of DNA however my writting and teaching skills are lacking to say the least.
I'm glad we have you to explain it in a straight forward and logical manner.

Obviously a normal will not throw the salmon mutant to any of its offspring, because it does not have a salmon mutant to give. Nobody is saying that a normal is het for salmon. But a salmon is het for salmon and wild-type at the salmon locus, the same as a "normal het for albino" is a normal het for albino and wild-type at the albino locus. What is being called a "super salmon" is simply homozygous for the salmon mutant at the salmon locus.

It seems to me this is what trips so many people up. The understanding of what homozygous and heterozygous really mean. Once they understand that a het for albino is also a het for wild type and that a salmon boa is het for both wild type AND salmon the rest seems to fall into place.

 

[M.Dwight]

And I need to remember to use the spell check

 

[crotalusadamanteus]

OK,
I am starting to grasp what you are saying.............. I think. LOL
And actually it is very close to what I have been learning, just a different look, and explanation.

Where i got a lil lost was the difference between the co-dom, and dom genes. It was put to me, (in plain english) a Dom gene will affect the whole litter immediately. A co-dom gene will pass to a percentage of the litter, (any percentage). And a recessive gene will not affect the litter immediately, but the litter will pass the gene to their litters.

What I grasped from what was said above, this is not true. I do understand that a dom gene has two copies of the same gene, and a co-dom gene one copy of mutant, and one of WT. This goes with what I have learned. But I still sorta think its co-dom. Simply by the way it acts. A super salmon/WT produces all salmons theoretically. Because it has a Dom gene. A normal Salmon only produces some.

I'll go read that Pea thing. Thanks for everything so far. Been pretty interesting. So don't give up on me. LOL

Ciao,
Rick

 

[Serpwidgets]

Where i got a lil lost was the difference between the co-dom, and dom genes. It was put to me, (in plain english) a Dom gene will affect the whole litter immediately. A co-dom gene will pass to a percentage of the litter, (any percentage). And a recessive gene will not affect the litter immediately, but the litter will pass the gene to their litters.

I think you are confusing "dominant" with "homozygous" and "codominant" with "heterozygous."

Dominant, codominant, and recessive are relationships between two alleles at the same locus. To put it in math terms, these are like Greater Than, Equal To, and Less Than.

Let's use two example alleles, call them A and a. Between any two alleles, there can be three genotypes: AA, Aa, and aa.

If one allele is dominant to the other, the other is recessive to it. In dominant/recessive relationships, there are two phenotypes. The AA and Aa genotypes create one phenotype, and aa creates a different phenotype.

If the alleles are codominant to each other, the three possible genotypes create three resulting phenotypes. That is, AA, Aa, and aa can all be visually identified.

----

Meanwhile, heterozygous and homozygous describe the same/different aspect of the pair of genes found at a locus. Homo means same, hetero means different. In math terms, these are kinda like Odd and Even.

If the gene pair is the same, it is homozygous.

If two different alleles are paired, it is heterozygous. It is also true that the individual is heterozygous for both alleles, since the pair cannot be "different" without two things to differ from each other. The wild-type is generally assumed when no second allele is mentioned. Thus, "het for albino and wild-type" gets shortened to "het albino."

So, AA and aa are both homozygous. They are not "dominant."

Aa is heterozygous. It is not "codominant."

I hope that made some more sense of it.

Using them as they are used in the above posts would be like saying that 7 is odd to 4 but even to 5, and even is less than odd.

In those terms, the results are explained a bit differently: The salmon allele is inherited by all offspring of a homozygous salmon parent, not because the gene is dominant, but because that parent is homozygous and thus cannot throw any other gene to its offspring. Since the salmon allele is dominant to the wild-type allele, and all of the offspring are carrying salmon, they will all express the salmon gene.

 

[M.Dwight]

Lets go over the very basics.

A locus (loci for plural) is a space on a chromosome where genes live or exist.

Each locus contains two alleles.

Each locus will inherit one of these alleles from the father and one from the mother.

If a locus inherits two same or like alleles from the father and the mother then it is said to be homozygous.

If a locus inherits two unlike alleles (say one albino allele from the father and one wild type allele from the mother then it is said to be heterozygous.

The two alleles at a locus create a relationship with each other.

This relationship will determine which alleles will be visible in the phenotype.

A locus with two like alleles (homozygous) is always visible in the phenotype. An albino boa is visibly albino because it has inherited the two like alleles on the albino locus. Homo means same so both alleles are same or like.

If a locus has two different or unlike alleles it is heterozygous. And which ever allele is dominant will be visible in the phenotype.

In boas the wild type allele is dominant to the albino allele. So if a locus has one albino allele and one wild type allele then wild type will be visible in the phenotype. This locus has one alblno allele and one wild type allele so it is said to heterozygous for both alleles. But only one allele is dominant.

If a boa has one salmon allele and one wild type allele then salmon will be visible in the phenotype because salmon is dominant to wild type.

Dominant just means that it will be visible in the phenotype when paired with an unlike allele. The unlike allele on the same locus that is not visible in the phenotype is said to be recessive.

 

[M.Dwight]

In my last post I basically explained the dominant/recessive relationship of alleles at a locus.

However, sometimes a locus will inherit two different or unlike (heterozygous) alleles and neither is recessive in relation to the other.

If neither is recessive then both must be dominant.

Remember dominant just means visable in the phenotype

Since both alleles are dominant and are working TOGETHER at the same locus we call this a CODOMINANT gene.

With a codominant gene Both allele will be visible in the phenotype.

If a locus has a allele for red and a allele for blue and red and blue are codominant in relation to each other then both red and blue will be visible in the phenotype.

Dominant, recessive and codominant are just words to explain the relationships of alleles at a given locus.

 

[M.Dwight]

With a codominant gene Both allele will be visible in the phenotype.

It would be more accurate to say..........
With a codominant gene both of the heterozygous alleles will express their traits in the phenotype.
But I was trying to keep it as simple as I could.

 

[crotalusadamanteus]

GENETICS 101

Nicely put. LOL
And well undrstood................Now
I read that pea theory thing long ago actually. A little differently put from page to page, this time around. It did help though.
Thanks for the lessons. You guys are great. LOL He has had enough to convince him now. HA HA

I'll probably be back for more, (I don't get enough), but for now, I got some studying to do.

Ciao,
Rick

 

[Serpwidgets]

BTW here's a link to my online genetics tutorial that works great for getting started, or as a refresher.

http://www.serpwidgets.com/Genetics/genetics.html

 

[crotalusadamanteus]

OK, I'm back.
Had to brush up on some math to take a test for the bosses "TSPS" to prove I know what I do as a surveyor. Go figure. I been proving it for 5 yrs. but that little card makes him feel better.

Back to genetics. Thanks Charles for the link. I will give it a look.
Where were we?..........Oh Yeah, (told ya i don't get enough) Co-Dominant.
You both express what leads me to my belief.

However, sometimes a locus will inherit two different or unlike (heterozygous) alleles and neither is recessive in relation to the other.

If neither is recessive then both must be dominant.

Remember dominant just means visable in the phenotype

Since both alleles are dominant and are working TOGETHER at the same locus we call this a CODOMINANT gene.

With a codominant gene Both allele will be visible in the phenotype.

I agree with this completely, and believe you can see the differennces in the three phenotypes.

If the alleles are codominant to each other, the three possible genotypes create three resulting phenotypes. That is, AA, Aa, and aa can all be visually identified.

Absolutely. Let me explain........
Perhaps in one way I am wrong to call it co-dom, when actually I believe it CAN be co-dom.

When the Wt alelle acts as dominant you get WT. We agree on that?
When the Salmon alelle acts dominant to the WT, the WT goes recessive, and you end up with a salmon het WT. (first two pics are of 2 I am leaning towards to purchase, the third an example only)
This would express the Salmon phenotype in it's heterozygous state, or mathematically, Salmon > WT..........

And when both alelles are paired as salmons, you get salmon expressed in its Homozygous state, or Salmon equal to Salmon, or Supers..........

And for the third phenotype, where both the salmon and WT phenotypes are expressed in their heterozygous state would be a salmon with visible signs of WT, or Salmon = WT, or Co-Dominant..........

Now I know i don't usualle talk all that loci and alelle stuff, I prefer plain ol' english, but i have read a little bit about this stuff also. I really do understand what you both are trying to say. And textbook speaking, I would have to agree with you both. I cannot say you are wrong.
But you guys have made me think ALOT about what you have said, and who knows, I may still be wrong. I can't afford that kind of research. But I believe that in a lot of salmons, both alelles are expressing their phenotypes in a co-dominant relationship. The last pic is not a prime example, but all I could find.

What say Ye?

Ciao,
Rick

 

[M.Dwight]

But I believe that in a lot of salmons, both alelles are expressing their phenotypes in a co-dominant relationship. The last pic is not a prime example, but all I could find.

What say Ye?

Ciao,
Rick

Salmon is as variable as wild type or normal.
In a litter of normal baby boas you will get some with light pigment, some with dark pigment and some that are in-between. But there is only one wild type gene.

The same is true of salmon. Once you produce enough salmons and supers you will see there is no real consistant difference between the two. Some salmons will be very dark and some will be very light with both reduced saddles and black pigment. The same is true of supers. This is why these days they are sold as "possible super salmons." Because the salmon gene is so variable there is no way to be 100% sure it is a super unless both of its parents are supers. Or, it was proved out to be a super through breeding trials.

Paul Hollander said it best in this post....
http://forums.kingsnake.com/view.php?id=926912,927843

 

[crotalusadamanteus]

That's a good point also. Maybe that's the connection I am missing. I do tend to get a little literal with things sometimes.

You are right though, they do almost always say "possible Super" LOL

Ciao,
Rick

 

[jsrocket]

Back to your original question. Yes if you breed an albino to a het albino, you would STATISTICALLY expect 50% albino, and 50%.

The salmon gene is at a different locus (location on the chromasome), and does not enter into the "albino" equation. However, I don't know if they could both be expressed, producing something that wasn't exactly either one.

If I understand what I've read here, and assuming the salmon trait is dominant, here are the possibilities:

Super Salmon phenotype = S
Salmon phenotype = s
Wild type = w

S X S = 100% Super Salmon

S x s = 50% Super; 50% Salmon

S x w = 100% Salmon

s x w = 50% Salmon; 50% Wild type

 

[jsrocket]

Second line should read: would STATISTICALLY expect 50% albino, and 50% normal.

 

[M.Dwight]

The salmon gene is at a different locus (location on the chromasome), and does not enter into the "albino" equation. However, I don't know if they could both be expressed, producing something that wasn't exactly either one.

Yes, both salmon and albino can be expressed in the phenotype. They are called sunglows.

If a mutant gene mask the presence of another mutant gene on a different locus it is called a epistatic gene. And the gene that is being masked is called the hypostatic gene. Neither salmon or albino are epistatic/hypostatic to each other so both are expressed in the phenotype.

 

[Serpwidgets]

If I understand what I've read here, and assuming the salmon trait is dominant, here are the possibilities:

Super Salmon phenotype = S
Salmon phenotype = s
Wild type = w

S X S = 100% Super Salmon

S x s = 50% Super; 50% Salmon

S x w = 100% Salmon

s x w = 50% Salmon; 50% Wild type

IMO the best way to work these is to use the actual genotypes, since the phenotypes are not what are being crossed. It's like trying to learn mutiplication by simply memorizing times tables and never learning counting or addition. (Then if the number is not on the memorized table, you're screwed. )

That is, use both genes present at the locus instead of one phenotype. The results are the same, but would make more sense to someone who is trying to understand what is going on underneath the phenotypes.

So instead of starting out by memorizing the results of "S X S" (and every other cross under the sun for every locus) you can use S for the dominant salmon mutant allele and + for the wild-type allele. There are then three possible genotypes at the salmon locus:
SS = "Super" Salmon
S+ = Salmon
++ = Wild-type

When you cross any two of these genotypes to each other, each baby receives one of the dad's genes, one of mom's genes. Using FOIL is an easy way to get the four possible outcomes. For example, if you are crossing 12 X 34 at a given locus you get:
First = 13
Outside = 14
Inside = 23
Last = 24

This is the same thing as doing a one-locus Punnett square:
<table border=1><tr><td></td><td>1</td><td>2</td></tr><tr><td>3</td><td>13</td><td>23</td></tr><tr><td>4</td><td>14</td><td>24</td></tr></table>

You can just substitute the 1 and 2 for the father's two genes, and 3 and 4 for the mother's two genes, and this will cover every cross at every (paired) locus, no matter what the parents' genotypes are.

-----

So, given that, the prediction for the original cross (Albino X hypo het albino) is:
At the Salmon Locus you are crossing ++ X S+
Results are: +S, ++, +S, ++ (half salmon, half normal)

At the Albino locus you are crossing aa x a+
Results are: aa, a+, aa, a+ (half albino, half normal)

You can then combine those two sets of results in a grid similar to a Punnett square:
<table border=1><tr><td></td><td><B>Salmon</B></td><td><B>Non-salmon</B></td></tr><tr><td><B>Albino</B></td><td>Albino, Salmon</td><td>Albino, Non-salmon</td></tr><tr><td><B>Non-albino</B></td><td>Non-albino, Salmon</td><td>Non-albino, Non-salmon</td></tr></table>

 

[jsrocket]

Absolutely. That is exactly how I did it, too. (except for your final step of combining the results). I didn't memorize that, I calculated it, but should have "showed the work" a little better. Your explanation is more understandable. Thanks.