Different Breeds of Guinea Pigs (A Breeders view)

Post Reply
User avatar
rshevin

Post   » Wed Aug 08, 2007 11:39 pm


Gah! Yeah, I DEFINITELY need a chart. I kinda understand.

Evangeline

Post   » Wed Aug 08, 2007 11:57 pm


What is unclear?

User avatar
MotaroRIP

Post   » Thu Aug 09, 2007 12:17 am


So white is a lack of a color gene? So white pigs lack genes? Is that why some people worry about white baby pigs being lethals?

Evangeline

Post   » Thu Aug 09, 2007 12:24 am


Are you on drugs? You can't 'remove' genes. White hair is caused by a spotting gene that blocks the red or black pigment.

And no, lethal whites are a whole other ball game.

User avatar
rshevin

Post   » Thu Aug 09, 2007 12:37 am


Well, it's not so much unclear as only a piece of the pie and a non-visual explanation (hence my obsession with charts, they're visual). I may not have had any mojitos, but I'm running on severe kitten induced exhaustion. That, and I never did enjoy molecular genetics.

Evangeline

Post   » Thu Aug 09, 2007 12:43 am


But pig genetics is cool!

For example, didja know that a silver agouti is really a golden agouti who's red points have not been expressed, leaving the tip white on a black hair shaft?

See how cool it is?

User avatar
rshevin

Post   » Thu Aug 09, 2007 12:51 am


And to think all this time I was just thinking sliver agoutis were really cute.

User avatar
MotaroRIP

Post   » Thu Aug 09, 2007 12:57 am


I don't get it. I'm taking genetics next year though.

User avatar
salana
GL is Just Peachy

Post   » Thu Aug 09, 2007 1:24 am


Colors are made by cell organelles called melanosomes, inside cells called melanocytes. Melanocytes move into the skin during fetal development.

Roan means there are fewer melanocytes, so some hairs aren't connected to melanocytes and get no color. Hairs with no color are white.

Lethal whites don't have any melanocytes at all, and that's also connected with nerve and tooth development. Hence their problems.

Every melanosome can make two kinds of color granules, black and red. The agouti allele says "when you try to make black, make a little red first".

Another gene can say, "everyone make black!", "everyone make red!", or "you guys make red and you guys make black". This leads to self black (or agouti), self red, or tortoiseshell (or agouti and red).

If it takes 5 steps to make black, chocolate is step 4. Step 5 is broken. So all the color granules coming out of the "black" color granule side of the melanosomes are unfinished, and chocolate color. Any place there's supposed to be black will be chocolate instead, including in the base of agouti hairs.

Lilac and beige are a problem with how much black (or chocolate) gets put into the hair. The melanosomes just don't spit out nice steady stream of color granules from the "black" side. So you get a very diluted black, which we call lilac. If you have step 5 of black not working, you get chocolate being diluted, which we call beige. The red side of the melanosome is a little bit affected by this, too, so it can't put out quite as much red and you get an orange pig. It's not as big a difference as black->lilac or chocolate->beige. This problem also makes the eyes pink instead of dark.

There's a whole series of alleles (different forms of a gene) that affect the 92802948343 steps of red-making. Some make it more yellow than red, so you get buff or cream anywhere the melanosome is trying to make red. This includes on the tips of agouti hairs.

One screws up the red-making process completely so the red side of the melanosome is spitting out colorless color granules. This means you get white anywhere you should have red--on the tips of agouti hairs (silver agouti), on self red or orange pigs (DEW or PEW), on brindled pigs (magpie).

Another one not only breaks the red side of the melanosome, it makes the black side have a problem in step 2 of black pigment making. If the melanosome is hot, the pigment can't get past step 2, and has no color. If the melanosome is cooler, like on the nose or feet, step 2 works most of the time, and you get however much black pigment, and whatever kind of black, you would normally get. This gives you a himalayan pig in black, chocolate, lilac, beige, silver agouti, depending on other genes.

Spotting is what most pigs with white patches have. It's like telling some of the melanosomes, "Hey, STOP MAKING ANYTHING!! You there, shut up! That group over there, nothing out of you! Everyone else, go about your business."

I hope that made everything clear as mud.

PiggieMamaKelly

Post   » Thu Aug 09, 2007 1:30 am


Wow, that was a great and enlightening explanation. But somebody pass the asprin... I have a headache.

Evangeline

Post   » Thu Aug 09, 2007 1:32 am


That was funny as hell! Especially at 2:31am after a few drinks.

User avatar
gpgrandma
Supporter in '07

Post   » Thu Aug 09, 2007 2:38 am


I hope there's not going to be a test...

User avatar
rshevin

Post   » Thu Aug 09, 2007 2:48 am


I'm determined to go through that all and understand but it's far too late, or early, depending.

User avatar
MotaroRIP

Post   » Thu Aug 09, 2007 2:51 am


I get it. Though a little late to be thinking like that.

Brandilynn
Who's your Branni?

Post   » Thu Aug 09, 2007 8:09 am


I love genetics. Its like that math where you had to prove a shape using sentences.

User avatar
salana
GL is Just Peachy

Post   » Thu Aug 09, 2007 9:30 am


Glad I could amuse you, E.

User avatar
Lucy+Lilly

Post   » Thu Aug 09, 2007 9:41 am


Holy crap! No wonder pigs have such varying colors!

User avatar
Jennicat

Post   » Thu Aug 09, 2007 10:15 am


I liked that explanation, salana. It gave me a mental image of pig genetics as being fueled by the lemmings from the old video game "Lemmings".

User avatar
salana
GL is Just Peachy

Post   » Thu Aug 09, 2007 4:03 pm


I like to think of it as little machines, some of which have busted parts, and they're all connected to some kind of network that sends them signals.

User avatar
WHEEKness

Post   » Thu Aug 09, 2007 8:13 pm


Salana, great explanation. Love it. Love piggy genetics. E, yes, the relationship between silver and golden agouti is very cool. I used to teach middle school genetics, and my pigs are definitely coming to school for the genetics unit next time I teach it.

Post Reply
476 posts