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Pearl, mutation of cream?

JNFerrigno July 29, 2011 July 29, 2011

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Oh...Pearl...on it's on locus, or on the same locus as cream? So basically....Cp or Prl?

Monsterpony Fri, 07/29/2011 - 22:54

Pearl is a different mutation of the cream gene. So there is C (non-cream), Ccr (cream) and Cprl (pearl).

CC=non cream/pearl
CCcr or CcrC= single dilute creme
CcrCcr= double dilute cream
CCprl or CprlC= pearl carrier (no phenotype change)
CcrCprl or CprlCcr = pseudo double dilute (ie palomino pearl)
CprlCprl= pearl

RiddleMeThis Sat, 07/30/2011 - 00:26

While MP is correct, you will more commonly see

crcr or NN for no cream
CRcr or NCR for heterozygous cream
CRCR for homozygous cream

prlprl or PRLPRL, NN for no pearl
PRLprl, NPRL, Nprl for heterozygous pearl
PRLPRL or prlprl for homozygous cream

Danni Sat, 07/30/2011 - 03:16

So it's now very much accepted and known that pearl is a mutation of cream, and not just very close to cream? If that's the case why do the labs treat it seperately, do they think people would not be able to understand it the way MP wrote it?!

RiddleMeThis Sat, 07/30/2011 - 11:05

[quote=Danni]So it's now very much accepted and known that pearl is a mutation of cream, and not just very close to cream? If that's the case why do the labs treat it seperately, do they think people would not be able to understand it the way MP wrote it?![/quote]
Why shouldn't they treat it separately? They treat Roan, Sabino 1, DW, and Tobiano all separately and they are all KIT mutations.

It isn't "confirmed" because the paper isn't out yet as far as I know, but it's as close to confirmed as we will get until that time.

JNFerrigno Sat, 07/30/2011 - 11:50

But with the kit mutations, cant they have mroe then 2 of those patterns at the same time?

Like...um....parking spaces.

Is the Kit locus(?) limited to two parking spaces so you can only have a horse expessing two kit mutations at the same time, or can they express more then two.

Daylene Alford Sat, 07/30/2011 - 14:52

Yes, for all practical purposes it is like having only two parking spaces.

Monsterpony Sat, 07/30/2011 - 17:34

[quote=Danni]So it's now very much accepted and known that pearl is a mutation of cream, and not just very close to cream? If that's the case why do the labs treat it seperately, do they think people would not be able to understand it the way MP wrote it?![/quote]

Davis hasn't published the paper (for mostly political/economic reasons, it seems, since Davis is the only lab that can sell the test if unpublished), but the research, inheritance studies and insider information all indicate that it is another mutation of the cream gene. While the notation RMT added does exist, it drives me nuts because, to me, that is more confusing especially given the different dominance of the mutations.

critterkeeper Sun, 07/31/2011 - 14:04

~x( I am with Daylene and more confused than ever...would it ever be possible to have a cremello/perlino/smokey cream that also is hz/HZ for pearl? From the above explinations I would guess not...it is either HZ for one or hz for both, but not HZ for both cream and pearl...right? :-?

Daylene Alford Sun, 07/31/2011 - 14:43

[quote=critterkeeper]~x( I am with Daylene and more confused than ever...would it ever be possible to have a cremello/perlino/smokey cream that also is hz/HZ for pearl? From the above explinations I would guess not...it is either HZ for one or hz for both, but not HZ for both cream and pearl...right? :-?[/quote]

If they are actually alleles of the same gene than this is not possible because to use the example of parking spaces each gene only has two. If they are alleles of genes that are very close to each other it could theoretically be possible but it would require a either a second spontaneous mutation of either cream or pearl or a crossover. The changes of a cross over at genes located so closely together would be next to impossible.

critterkeeper Sun, 07/31/2011 - 15:04

Yep, that's what I thought...but can't blame a girl for being hopeful...lol
:rofl

colorfan Sun, 08/14/2011 - 08:38

Just to be clear, you couldn't have a double dilute cream and a double dilute pearl, or a double dilute of one and a single dilute of the other.
Only a single dilute of cream and pearl, because they are so close on the gene chain?

Daylene Alford Sun, 08/14/2011 - 09:12

[quote]Just to be clear, you couldn't have a double dilute cream and a double dilute pearl, or a double dilute of one and a single dilute of the other. Only a single dilute of cream and pearl, because they are so close on the gene chain?[/quote]

This is correct

RiddleMeThis Sun, 08/14/2011 - 15:28

According to Horsegen it would be hypothetically possible for a crossover to occur and thus make and Homozygous Cream Heterozygous Pearl or Homozygous Pearl Heterozygous Cream possible.

Its highly highly unlikely and not even a possibility worth considering for breeding probabilities but it IS possible.

critterkeeper Tue, 08/16/2011 - 18:03

So, Daylene, you are saying I should stash this possiblity right up there with the probability of my hitting the lottery - twice! =))

Monsterpony Tue, 08/16/2011 - 23:20

It is the same gene, just different mutations. Also, you can have more than one copy of a gene; it is just rare. A gene is quite a lengthy piece of DNA. Some mutations are as simple as a single base pair change. Grey is a duplication mutation where a section of DNA was copied and reinserted so now two sections of the gene exist where once only one did.

Threnody Tue, 08/16/2011 - 23:51

I sometimes wonder if gray, either through cross over or another duplication mutation made more copies of itself in certain lines of arabs. Especially considering how fast some of the foals gray the second they hit the ground.

JNFerrigno Wed, 08/17/2011 - 04:52

If horsegen is the same person I'm thinking of (Mules?) then yeah she had explained to me once that it could be possible.

I guess because in science we learn to never say words like always, and never, because there will be exceptions to the rules that will counter that.

I think in this case since there have been mutations where species have extra genes (can't think of any in horses but I think it's happened in humans before) that chance of a random mutation occuring and a horse having three of the same gene could in theory happen. For all we know it could have happened an just not been viable. who knows.

Daylene Alford Wed, 08/17/2011 - 06:15

[quote]If that's the case, then it ISN'T the same gene as cream, just so close it's treated as such?[/quote]

It's thought to be an allele of cream, but because UC Davis hasn't published their research, we can't say for sure. It is possible that it isn't a allele of cream just very very close.

rubberduckyyy Wed, 08/17/2011 - 23:54

Horses cannot carry just pearl, right? They have to carry like one creme and pearl? Is that right? Pearl is one thing it seems I cannot wrap my mind around ~x(

Monsterpony Thu, 08/18/2011 - 01:08

No, horses can easily carry one pearl. They would just not express it. Pearl only expresses phenotypically if it is homozygous (CprlCprl) or if it is paired with a cream (CcrCprl). A pearl carrier (CprlC) has one non-cream allele and one pearl allele. They don't have any change in appearance from a non-cream horse (CC).

rubberduckyyy Thu, 08/18/2011 - 11:45

I think what confuses me is that it's written "Cprl" instead of it's own notation (like Prl, prl or something). If that makes any sense :rofl

Daylene Alford Thu, 08/18/2011 - 12:34

[quote=rubberduckyyy]I think what confuses me is that it's written "Cprl" instead of it's own notation (like Prl, prl or something). If that makes any sense :rofl[/quote]

It is written this way because it is a recessive on the C locus (theoretically). Prl (with a capital) is reserved for Dominants. I think it would be more correct to use superscripts. With CC being No cream or pearl and C[sup]cr[/sup] denoting cream and C[sup]prl[/sup] denoting pearl. If you compare it to Agouti The C would be similar to A as they are both wild type. C[sup]cr[/sup] would compare to A[sup]t[/sup] and C[sup]prl[/sup] would be comparable to a.

RiddleMeThis Thu, 08/18/2011 - 12:58

Not everyone writes it like that, which makes it even MORE confusing. Especially since the research Universities where a lot of people get there information from DON'T write it that way. They write it simply CR and PRL.

rubberduckyyy Thu, 08/18/2011 - 15:16

[quote][b]admin wrote[/b]:
It is written this way because it is a recessive on the C locus (theoretically). Prl (with a capital) is reserved for Dominants. I think it would be more correct to use superscripts. With CC being No cream or pearl and Ccr denoting cream and Cprl denoting pearl. If you compare it to Agouti The C would be similar to A as they are both wild type. Ccr would compare to At and Cprl would be comparable to a.
.[/quote]

Oh my gosh it makes so much more sense now that you compared it to Agouti!! Thank you!!

And Riddle that's the way I was taught, too. If it's more correct to do it the other way I don't see why they just don't do it :-?

RiddleMeThis Thu, 08/18/2011 - 17:26

[quote=rubberduckyyy]
And Riddle that's the way I was taught, too. If it's more correct to do it the other way I don't see why they just don't do it :-?[/quote]
Because as you've shown it's confusing to a lot of people.

colorfan Thu, 08/18/2011 - 17:43

Interesting, so pearl could be out there more than thought.

One copy of cream is called a simple dominant (I think) so what is one pearl called? Two pearls, and I will raise you one...... :grin: