Some thoughts on the lavender gene

I've been doing some research lately on pigments of reptiles and amphibians and think I may have stumbled on why lavender cornsnakes are so much different than any other color mutants of cornsnakes. This is just a theory but I think I may be on to something. But in order for me to explain it I'll first need to give a little lesson on reptile pigments. I'll do my best to keep it as simple as I can so as not to bore you to death with all the fine details...only the bare bone basics.

So here go's..
Almost all of the colors we see in snakes come from color bearing cells called
Chromatophores. There are three sub-classes of chromatophores in snakes. 1. Xanthophores, 2. Melanophores and 3. Iridophores. These three types of
chromatophores have different pigment functions. The Xanthophores produce the yellow to red pigments. And the Melanophores produce the brown and black pigments. And the iridophores react with xanthophores and melanophores to reflect other hues of color(like green and blue.) The xanthophores and iridophores reside in the dermis layer of the skin just beneath the epidermis. The melanophores can be in both the dermis and epidermis. The epidermis is a layer of about 30 dead skin cells deep on top of the living dermis layer. The Chromatophores are also arranged in layers. The top layer contains the Xanthophores, in the middle are the iridophores and the bottom layer is the Melanophores. The Melanophores also have finger like projections called dendrites that can extent upward between and
around the iridophores and Xanthophores. The Melanophores can send melanin (the brown or black pigment) through these dendrites to the surface of the dermis and into the epidermis partially covering up the pigment produced by the Xanthophores. This is why some snakes like Boa constrictors can quickly change from light to dark.

OK. Now that we've gotten that out of the way.....

If you've ever seen a baby snake that was born or hatched prematurely you may have noticed it had a lot less pigment compared to a fully developed baby. Thats because all of the chromophores had not yet migrated from the neural crest to the dermis of the skin. Early in the embryonic development of snakes the cells that will eventually become the chromophores are being created in a region called the neural crest. I like to think of the neural crest as a cell nursery. At different points in development these cell leave their neural crest home in waves and seek out other parts of the developing
embryo. The waves of pigment cells leaving the neural crest and migrating to the dermis are called chromatoblasts. But sometimes things go wrong and there is a defective mutant gene that will not allow chromatophores to develop in the neural crest or the defective gene will prevent the migration of the chromatoblasts to the dermis. Either way no chromatophores ever reach the dermis. This condition is called leucism. Leucistic snakes have no melanophores, no xanthophores and only very limited amounts of iridophores and their skin appears completely white. However, eyes get most their pigment from cells that migrate from a region called the neural tube and not the neural crest. So the eyes are affected very little by the leucistic mutant gene. Leucism can be classed as a genetic malfunction of the neural crest.

So what does this have to do with lavenders?

The phenotype of a homozygous lav is a reduction of all common cornsnake pigments like red, orange, yellow, black and browns. Now I asked myself how
could a singe recessive gene possibly be limiting the production of melanin
(needed to make black and brown color), pteridine (needed to make yellow pigments), and carotenoid (needed to make red and orange pigment.) I find
it hard to believe a singe gene could control so many chemical actions. And
that's because it DOESN'T! I believe that like the leucistic gene the
lavender gene is reducing the amount of pigment bearing chromatophores from reaching the skin. The lavender gene is a malfunction of the
neural crest. Unlike the leucistic gene however some chromatophores do
reach their destination. Kind of a wanna-bee leucistic.

Keep in mind this is just a theory. But from what I know about pigments, cell migration and genetics it does make sense to me.

Oh btw this theory also explains their light purplish/brownish color. It also explains why lavenders will partly "mask" all other color mutants like caramel and anery. With limited chromatophores lavenders are changed very slightly when another color mutant is added to the mix.

I'm a boa breeder as well as a corn keeper. I once had a litter of boas that were born only about half way through their gestation period. I can remember thinking to myself that in color those babies looked just like lavender corns. The more I think about this theory the more I like it. It may also explain some of the strange things we see going on in other color morphs(like melanan masking the red in aneryA's and yellow masking the reds in caramels, but I'll leave that story for another post.)

Wow. I will need to re-read this, over and over to let it all sink in.

Very interesting hypothesis.

It a interesting hypothesis, it also makes alot of sense. The lavender morph has always intrigued me, I just couldn't quite put my finger on how a grayish/purple/brownish snake came into existence.
Too bad corn genetics isn't a top priority for scientists LOL.

I wonder, if the lavs are a wanna be leucy, how many generations of line breeding would it take to produce a true leucy? Might be a interesting project.

Corn_Oasis said:

I've been doing some research lately on pigments of reptiles and amphibians and think I may have stumbled on why lavender cornsnakes are so much different than any other color mutants of cornsnakes..... Oh btw this theory also explains their light purplish/brownish color. It also explains why lavenders will partly "mask" all other color mutants like caramel and anery. With limited chromatophores lavenders are changed very slightly when another color mutant is added to the mix.

Click to expand...

Excellent post! Your line of thinking is easy to follow and you come to a quite logical conclusion.

Interesting stuff! So we could consider the Lavender as Hypoleucistic?

This may very well explain why adding Amelanism to a Lavender/Anerythristic pretty much leaves you with a Snow looking animal. But this is somewhat confusing in that it does not affect the PATTERN such as you see in Amelanistic Charcoals (Blizzards).

Food for thought anyway...

Rich Z said:

Interesting stuff! So we could consider the Lavender as Hypoleucistic?

This may very well explain why adding Amelanism to a Lavender/Anerythristic pretty much leaves you with a Snow looking animal. But this is somewhat confusing in that it does not affect the PATTERN such as you see in Amelanistic Charcoals (Blizzards).

Food for thought anyway...

Click to expand...

We think alike.
This is something I've already thought about in great detail and do have the answers. But it's late and it'll take another looong post to fully explain. So I'll post again after some sleep when I'm thinking clear. :boring:

Thanks for the excellent post on lavenders!! I look forward to reading other posts by you

Question for another thread perhaps - I don't want to hijack this one :sidestep: Although it does sort of tie in here - with dendrites & melanophores

What is your view on dilute corn snakes? Have other reptile species exhibited "dilute" morphs, which might relate / explain what we are seeing in corn snakes? Dilute has proven to be recessively inherited by several breeders.

The general consensus is - all dilutes have clear sheds regardless of color or pattern.... normals, anery, anery motley, ect...

Someone proposed perhaps the dendrites of the melanophores were not reaching the epidermis. Hence - a dilute anery A still had relatively dark pigment from melanophores, but shed clear.

Thanks ahead for any comments!!

Excellent post. I have always loved the lavender cultivar because of how different it is to the "starting point" in corns, ie a red/brown/orange/yellow snake with black borders!

I wonder if the same hypothesis could apply to the dilute gene, although to a lesser extent? IE only the melanophores being "switched off".

Hypoleucistic... very very interesting idea. So whats a HYPERleucistic?

Just out of curiosity, but are there any indications in any other animals (not necessarily limited to snakes) where neural crest mutations can also be associated with a higher percentage of developmental abnormalities?

Rich Z said:

Interesting stuff! So we could consider the Lavender as Hypoleucistic?

This may very well explain why adding Amelanism to a Lavender/Anerythristic pretty much leaves you with a Snow looking animal. But this is somewhat confusing in that it does not affect the PATTERN such as you see in Amelanistic Charcoals (Blizzards).

Food for thought anyway...

Click to expand...

This is where it gets a bit tricky.

Anerythristic 'A' is not really a anerythristic gene. It is a replacement and concentrate gene. It replaces much (but not all) of the xanthophores with melanophores (thus the pet store name of black albino.) The fact that reds, pinks and oranges make up the phenotype of many snows proves that the name anerythristic'A' is a misnomer.
Anerythristic'A' is also a concentrater of both melanphores AND
xanthophores. It will consentrate many of the melanophores along the borders of the pattern. This in fact is the main difference between anery'A' and charcoals. Charcoals don't concentrate the melanophores they disperse them through out the whole dermis. This is why charcoals have a "smeared" or "smudged" phenotype and the blizzards lack a strong
concentrated pattern. Anery'A' will also concentrate some of the
xanthophores along the chin and neck regions giving some a very yellow forward half of the body. Just for reference check out this photo of what I believe to be a anery'A'/lavender. Notice the black bordering and yellow.
http://cornsnakes.com/forums/showthread.php?t=12992

Lets move on...

One of the myths in snake breeding is that lack of melanin = white pigment. But this is false. Grab yourself a amel Okeetee and check out the "white" borders surrounding the dorsal saddles. You will discover these borders do have some white but those scales are mostly clear or
transparent. Now take a look at a run of the mill snow corn, one that hasn't been selectively bred for lots of color like corals. What gives these snows a pattern? The pattern is mostly the contrast between white scales and clear or transparent scales (with just a tad bit of xanthophore yellow and pink thrown in.) These snows have a visible pattern because the lack of melanin in the melanophores causes these cells to become
completely see through clear. The areas that are truly white is where there are no pigment cells at all. So, transparent = no melanin in the chromatophores and white = no chromatophores. This is why leucistic ratsnakes are white and the "white phase" albino black ratsnakes have a transparent phenotype.

Can you please get to the point already!

Take another look at that photo in the link above. You will notice the black pigment has been concentrated along the borders and there is also some concentration of yellow along the chin/neck area (btw I believe most of the lavenders showing yellow pigment are also homozygous for aneryA.) Now what would happen if we add amel to this snake? That's right...the black borders would become transparent (creating contrast with the white), the yellows in chin/neck would become brighter and the few chromatophores containing the red (pink) pigments would more easily be seen. In affect we would have a snake whose phenotype resembles a run of the mill snow corn. The Snopals only differ from the Opals because when anery'A' is added to the mix it both ADDS and concentrates black along the borders causing contrast between transparent scales and true white scales. And because it concentrates the yellow pigment up front.

Am I right or wrong? There is a way to prove this one way or the other. If I'm correct it should be impossible to create very strong A+ coral snopals. This is because there simply is not enough chromatophores with the lav gene to hold that much red or pink color. Only time will tell.

Rich Z said:

Just out of curiosity, but are there any indications in any other animals (not necessarily limited to snakes) where neural crest mutations can also be associated with a higher percentage of developmental abnormalities?

Click to expand...

Tons. The list goes on and on. Much of the cranial, heart, skeletal and nervous system all arise from the neural crest.

In humans many abnormalities like certain cancerous tumor growths, blindness, ocular development, human albinism and cleft palettes/lips.

In birds malfuctinoning neural crest has caused them to develop no cranial mass (soft heads.)

In reptiles a lack of or reduced pigment (including piebald), ocular abnormalities, complete lack of eye(s) and vertebral kinks.

And in lab mice the list is a mile long.

Corn_Oasis said:

Tons. The list goes on and on. Much of the cranial, heart, skeletal and nervous system all arise from the neural crest.

In humans many abnormalities like certain cancerous tumor growths, blindness, ocular development, human albinism and cleft palettes/lips.

In birds malfuctinoning neural crest has caused them to develop no cranial mass (soft heads.)

In reptiles a lack of or reduced pigment (including piebald), ocular abnormalities, complete lack of eye(s) and vertebral kinks.

And in lab mice the list is a mile long.

Click to expand...

Interesting......

I've noted over the years that the percentage of kinks is much higher in Lavenders then in any other group I have worked with. So perhaps this is further evidence that your hypothesis is right on the money....