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Pearl

Hey, I have a hard time getting my head around that a Pearl/Cream horse must pass on either a Pearl or a Cream gene to it's foals. It seems to be something to do with Pearl being a cream mutation, but if they can test for Pearl, then isn't it different enough to Cream to have it's own genetics.... I think I'm just confusing myself! If I think of Pearl as being similar to At, thus Pearl should be written Cr with a little 'p' maybe? Because it's just another form of Cream?? Anyone know more about this to explain it better to me?! Cheers Danni

Daylene Alford Sat, 05/02/2009 - 19:03

Pearl is recessive and completely separate from cream. They are inherited separately. So it is possible for a cream + pearl carrier to have a foal that has neither cream or pearl. It acts as sort of a "helper" dilution when cream is present to dilute more than cream would on its own. Technically I think that pearl would be designated with a small p since it is recessive.

For example a horse with one copy of pearl and no cream will show no dilution.

A horse with 2 copies of pearl with show dilutions that is similar to champagne.

A horse with one copy of pearl and 1 copy of cream with show more dilution then cream alone. For example cream+pearl dilutes black points where cream alone does not.

Hope that helps,

Daylene

NZ Appaloosas Sat, 05/02/2009 - 21:37

Pearl is a separate gene from creme, but works "in cooperation" when creme is present, to dilute the coat colour.

Diane

Heidi Sat, 05/02/2009 - 22:18

[quote="admin"]Pearl is recessive and completely separate from cream. They are inherited separately. So it is possible for a cream + pearl carrier to have a foal that has neither cream or pearl. It [u]acts as sort of a "helper" dilution when cream is present[/u] to dilute more than cream would on its own.

[b]For example a horse with one copy of pearl and no cream will show no dilution.[/b]
[b]A horse with 2 copies of pearl will show dilutions that is similar to champagne.[/b]
A horse with [u]1 copy of pearl and 1 copy of cream with show more dilution then cream alone[/u]. For example cream+pearl dilutes black points where cream alone does not.
Daylene[/quote]

I am confused by reading 'pearl is recessive'...wouldn't that mean in heterozygous form, it would have no affect on coat color? That it would need two copies (homozygous) to exhibit coat color changes?
I understand about being a carrier, much like a heterozygous black (Ee) can carry red, or how red horses can carry agouti ([i]eeAa or eeAA[/i]) with no visible clue of the agouti gene...
But PEARL:
In one dose with no cream it visibly changes nothing.
One pearl with one cream creates more dilution to the coat than just a cream gene.
Two doses will change the haircoat even if cream is not present.

It doesn't seem to fit how I think of recessive. I am thinking recessive needs to have a matched pair ([i]like ee[/i]) to be visible and pearl doesn't seem to follow that exactly. Can someone please help me understand?

Also, what about two pearl genes on a double dilute...with that also visibly change the haircoat of the horse?

accphotography Sat, 05/02/2009 - 22:31

One copy of pearl alone will have no effect on the coat.

Two copies of pearl with no cream gives you a single cream appearance (reds look palomino, etc.)

One copy of pearl with one copy of cream give you a pseudo double dilute.

As far as I know two copies of pearl and one of cream, or two copies of cream and one of pearl, or two copies of pearl and two of cream would probably all look very similar. Indistinguishable I'd suspect. Hard to say as there aren't any at this time that we're aware of.

Pearl is recessive, it's just "cream activated". Cream somehow turns it on, even in it's recessive form.

Monsterpony Sat, 05/02/2009 - 22:32

When cream is not present, pearl is a recessive gene. It takes two copies to cause any effect on the coat color.

CC PP = carries no pearl gene
CC P[i]p[/i] = no sign of pearl, but is a carrier
CC [i]pp[/i] = Pearl coat color
CcrC PP = normal single dilute cream (pali/buckskin/sm black)
CcrC P[i]p[/i] = Pseudo double dilute cream (looks cremello/perlino/smoke black

CMhorses Sat, 05/02/2009 - 22:33

Also what about pearl on a different dilute than cream? Does it have the same effect on a dun or champagne?

And I think the way pearl works makes sence, Pp-no visible effect,PP-visible effect, but when another dilution is present (possibly just cream) then the Prpr would be visible since the coat is already diluted to begin with... you could think of it like cream on black.

Danni Sat, 05/02/2009 - 23:43

[quote="admin"]Pearl is recessive and completely separate from cream. They are inherited separately. So it is possible for a cream + pearl carrier to have a foal that has neither cream or pearl. [/quote]

Ok, this isn't what I've been told. By.. Carolyn Shepard I think it was. She says Pearl acts as a type of cream, thus a cream/pearl has to pass on either cream or pearl to their foal.

And I have to say I have been keeping an eye on all foals born from Pearl/Creams so far and I think it's 5 this season and 4 last and yes all have either pearl or cream. Not both or neither. So I'm beginning to think Carolyn's theory is right. I mean more foals will make it more certain but it's holding out so far!

So anyone want to explain how this is so!
Cheers

Danni

Maigray Sun, 05/03/2009 - 01:19

Well, pearl is like cream in the sense they are both dilution genes and both dilute the coat in similar ways. You could say the same of champagne. I thnk this is just a matter of miscommunication. Pearl is not cream, and they inherit seperately. That is not a theory (as far as I'm aware). If a horse has one pearl gene and one cream gene, it has a 50% chance of passing on either one. The odds are, of course, in your favor for passing at least one on to a foal from such a horse, but it is not 100%.

Danni Sun, 05/03/2009 - 02:45

Nope, not miscommunication. Well at least not to me, unless Carolyn got some miscommunication?

This is her Pearl documentation. She was the one that helped find Pearl as I understand.

[i]The pearl gene, “Prl,” is the most recently discovered equine dilution gene, and is remarkable because it does not behave in a dominant manner.
A horse carrying one copy of the pearl gene may have pink speckles on its black skin, or may not show any skin differences whatsoever.
Essentially, a red, bay, brown or black horse who carries one pearl gene, can not be distinguished from a regular red, bay, brown or black horse.
However, when two pearl genes are present, the horse experiences a single dilution of the hair coat, and a double dilution of the skin, accompanied by a certain degree of skin freckling.
The eyes of the adult homozygous pearls are dark. These horses are often mistaken for champagnes. The most common manifestation of the pearl gene is in combination with the cream gene.
Pearl/cream horses closely resemble the champagne/cream shades, and are often only distinguishable from one another by testing.
Pearl/cream horses have pink skin with champagne-like freckles, and generally have dilute (yellow to green) eyes.
[b][size=150]Pearl is either an allele of the cream gene, or is closely linked to cream.
Breeding studies indicate that a horse can NOT receive both a pearl gene and a cream gene from the same parent.
Thus, a pearl/cream horse will have one parent with a cream gene, and the other with a pearl gene. [/size] [/b]
There is a DNA hair test for pearl. [/i]

I thought I'd bring it up here as wanted to hear everyones thoughts on it being part of cream, I hadn't seen anyone here mention it before. People I know with Pearls in contact with Carolyn accept it as fact. I'd like to see a few more foals but it's holding out so far. Nothing has tested to disprove the theory.
Cheers

Danni

Maigray Sun, 05/03/2009 - 03:06

Then she does know something we do not. I did not quite understand what you meant until now. There is no mention of it on the information on the UCDavis site, but as they have no yet published (correct?) it should be taken with a grain of salt anyway. If that is her theory, so be it. Without the published results, it's a moot point for me.

Fledgesflight Sun, 05/03/2009 - 04:33

Wow..I had never known this was written about Pearl- What drew (where are the results/studies) them to this conclusion- or is it merely just an opinion?

Danni Sun, 05/03/2009 - 04:50

Well I just thought it was opinion, but have been told in no uncertain terms that it's fact LOL!

Personally I've just treating it as an interesting theory, and taking it with a grain of salt as you say. But I've contacted a couple of others that are having foals due this year from their Pearl/Cream stallions/Mares and the theory still is holding out. I just realised there is about 10 this year in the Gypsies alone so far.

I'm trying to find a non pearl or cream (or both) foal from a pearl/cream parent. One stallion last year had a pearl/cream filly but it was to a pally mare. So I'm starting to think there is something to this theory. Realistically I only know of Gypsy foals, Carolyn would have access to many more non gypsy foal information I would imagine, thus a much greater group on which to make these statements.
Cheers

Danni

Heather Sun, 05/03/2009 - 06:25

You can search Barlink macho man foals and find some horses to test theroys, there was some confusion about "Turnin up the heat" and his dam 's color and was debated for some time or a couple times as to what her color truly was..I just skimmed this thread so may have nothing to do what what is being said, more coffee and open my eyes some more I have to read closer , lonnnngggg horse show yeaterday and Im burnt to a crisp and TIRED!

Maigray Sun, 05/03/2009 - 09:23

I actually meant take the UCDavis information/test with a grain of salt, as they've not published! But it's good sense either way. It changes things a lot, makes everything much more interesting.

accphotography Sun, 05/03/2009 - 10:17

This is simply not true. What she is claiming is genetically impossible based on the laws of inheritance. Pearl and cream are not alleles of the same gene and they are NOT even linked. Even if they were, her theory can't hold water. She says every pearl/cream has one pearl parent and one cream parent, but that a horse who receives those two genes from it's parents can not pass them both on to it's foals? That's just not possible. If they are not linked then each gene will pass at the standard 50% rate. If they ARE linked, both will pass together MOST of the time (the percentage will vary depending on the actual location of the genes in relation to each other). You will get a foal with neither, or both.

The only way her theory could hold water was if pearl and cream were alleles of the same gene, but they are NOT. This, we know, is certain.

There is plenty of evidence against her claims in the Paint breed. When I get home tonight I'll find some.

accphotography Sun, 05/03/2009 - 11:55

Another thought... If pearl were just another allele of cream, then every pearl carrier would test positive for cream, and we know this is simply not the case.

Maigray Sun, 05/03/2009 - 14:55

Darn UCDavis for not publishing! After thinking about it some, there is one large hole in the theory. If cream mutated, then we would be dealing with 3 possible alleles at the locus. Every animal carries 2 copies of a gene. IF she were correct, then why could an animal not have a cream allele and a pearl allele at both sites? I need to go back and review the background on cream...

Daylene Alford Sun, 05/03/2009 - 15:33

Actually if we could find a Cr Cr horse that also carries pearl it would disprove this theory. Anyone care to have a go at that one?

accphotography Sun, 05/03/2009 - 16:34

Actually Maigray I think you may have misinterpreted said hole. She did say that a horse could be pearl+cream, just that said horse couldn't pass both on to it's offspring (at the same time, in other words no pearl+cream from pearl+cream and non dilute parents).

I've given it a go Admin. I can't find one. Well, I take that back. I can't find a TESTED one. I've found tested double dilutes from parents that carry pearl, but to my knowledge they were not tested for pearl (lack of understanding on the owner's part that they could carry both pearl and cream).

I've just written an acquaintance of mine who stands a pearl+cream stallion to ask if she has any tested non pearl, non cream foals from him, but she told me she never bothered testing them. She also told me she hasn't bothered testing even if palest cream based foals because she is under the impression that he can not pass on both cream and pearl to the same foal. :BH :BH :BH

I am doing as much digging as I possibly can on this so I can disprove it. I am 100%, no question, certain this is not true.

Morgan Sun, 05/03/2009 - 16:35

It actually makes a LOT of sense to me, especially with the extreme reaction that pearl has to cream.
[quote="Maigray"]Darn UCDavis for not publishing! After thinking about it some, there is one large hole in the theory. If cream mutated, then we would be dealing with 3 possible alleles at the locus. Every animal carries 2 copies of a gene. IF she were correct, then why could an animal not have a cream allele and a pearl allele at both sites? I need to go back and review the background on cream...[/quote]
I dont quite understand you here? a gene lucus is a single spot on the dna with one allele on each strand (the two copies).
IF Cream and Pearl were mutations of the same gene it would work just as she says:

Non dilut horses would have wild type allele on each strand: nondilute/nondilute
Single cream dilute has a cream mutation on one and wild type on the other: cream/nondilute
Double cream dilute: cream/cream
single pearl would ahev a pearl mutation on one strand and a wild type on the other: pearl/nondilute
double pearl: pearl/pearl
cream pearl would have pearl mutation on one strand and cream mutation on the other: pearl/cream
and they pass on only the dna of one strand so its either or in the case of pearl cream

[quote]
Another thought... If pearl were just another allele of cream, then every pearl carrier would test positive for cream, and we know this is simply not the case.[/quote] not necesarily, they would have been looking for the actual code that says "cream" and and other variations at the locus would have been maked as "negative"

[quote]The only way her theory could hold water was if pearl and cream were alleles of the same gene, but they are NOT. This, we know, is certain.[/quote]
How do we know? :?

linking of the gene would NOT hold water. She does need to take that part out. Linking simply impies a close proximity on the dna where alleles pass on together with others on the same strand. if it was linking you could get a horse with both cream and pearl on the same strand and wild type in each place on the other, and foals would either be Both or non. kind of the oposite of what she's trying to prove.

Maigray Sun, 05/03/2009 - 16:52

You're right. I was confused. I was thinking she was saying they couldn't carry them both at the same time, but it was they could not both pass on, which would work that way. So what I said actually supports her theory. Interesting...

accphotography Sun, 05/03/2009 - 16:53

[quote]The only way her theory could hold water was if pearl and cream were alleles of the same gene, but they are NOT. This, we know, is certain.[/quote]
[quote]How do we know? :? [/quote]

Because, do you really believe UC Davis, who found the pearl gene and test for the cream gene, would continue to test them separately and never mention that they are both alleles of the same gene??? Also, if I'm not mistaken, I have been told by a researcher (I forget which one, but it could only be one of two) that it is not even on the same chromosome as cream. Also, apparently UC Davis has released something about pearl, or another lab has found it themselves... Avian Bio-Tech is testing for pearl now.

[quote]linking of the gene would NOT hold water. She does need to take that part out. Linking simply impies a close proximity on the dna where alleles pass on together with others on the same strand. if it was linking you could get a horse with both cream and pearl on the same strand and wild type in each place on the other, and foals would either be Both or non. kind of the oposite of what she's trying to prove.[/quote]

No, I agree linkage doesn't hold water.

accphotography Sun, 05/03/2009 - 18:05

[quote="Heather"]http://www.barlink.com/

2 pearl on chestnut

[img]http://www.barlink.com/608Rustyrs2.jpg[…]

wish I could find macho lady lass she is 2 pearl and creme, looks cremello.[/quote]

Machos Ladys Lass is her name. She can not be 2 pearl and cream. She only has one pearl parent, and has NO CREAM in her pedigree whatsoever. I've just spent about an hour and a half combing her pedigree. There does appear to be dun, that appeared out of NOWHERE, but no apparent cream. Her pedigree must be EXTREMELY messed up.

We need Horsegen.

Danni Sun, 05/03/2009 - 18:20

[quote="accphotography"]Because, do you really believe UC Davis, who found the pearl gene and test for the cream gene, would continue to test them separately and never mention that they are both alleles of the same gene??? [/quote]

This is the part I was having trouble with, surely if pearl was a type of cream they would have noticed when they found Pearl??? Rather than just notice down the track that horses seemed to only pass on either pearl or cream and not both...

Is there any precedence set where a gene we can test for has three possibilities?? (so prl, cr and n) Just wondered what it would look like to the researchers because don't they often just look for the 'n'??

I'm still confused how this would work if we assume the theory is right LOL!!
Cheers

Danni

accphotography Sun, 05/03/2009 - 18:26

Not at this time Danni. I think agouti will prove to have 4 alleles, but the researchers as a whole have not experienced that in horses, no.

Heather Sun, 05/03/2009 - 18:45

Humm, I thought she had on creme, I do recall the DUN question...but isnt her son Turnin up the heat bucky? I forget who his sire was , isnt he one creme? Its been a while since he was a foal and this debate came about.

accphotography Sun, 05/03/2009 - 18:47

I've just finished reading the Paint Horse Journal's article on pearls. Very interesting. Based on what I read, it sounds like UC Davis supports Carolyn's theory... or did anyway before they found the mutation.

If this is truly the case, my opinion of UC Davis just took a big turn (and now Avian Biotech/Animal Genetics as well).

RiddleMeThis Sun, 05/03/2009 - 18:51

I will say this Heather....there is something FUNKY goin on with this family....Im going to post a thread about it later....but...just wow...

accphotography Sun, 05/03/2009 - 18:57

[quote="Heather"]Humm, I thought she had on creme, I do recall the DUN question...but isnt her son Turnin up the heat bucky? I forget who his sire was , isnt he one creme? Its been a while since he was a foal and this debate came about.[/quote]

Turnin up the Heat looks bucky. His sire is OBVIOUS chestnut (Coolest, a dark liver). He has dun foals out of non dun mares despite his lack of dorsal stripe.

Ladys Lass is CLEARLY diluted more than just once. She is proven black based so there is no way she's not at least twice diluted IMO. She is PROVEN cream and PROVEN dun. However, she should have NOTHING more than a single pearl based on her pedigree.

Her dam, Rich n Rare's parents are both bay, however she is PROVEN dun and cream. PROVEN.

This is unbelievable.