Reptile & Amphibian Forums

Can this occur and if so what is it called?

Can you have a mutation that is sex linked in a way that a male can not make another male mutation but a female can?

The only way to get a male mutation is by breeding the female mutation of it?

I don't know if this occurs but I was wondering about that...

Thanks - -Kevin
-----
"Satan™" is a registered trademark of NERD, Inc. Any copyright infringement is punishable by ETERNAL DAMNATION and some other terrible stuff.

Very good question Kevin, and the answer is yes.

If a male carries the mutation, but never expresses it, then it would be called "sex-limited". If the male expressed it to a lesser degree, or on fewer occasions then it would be "sex-influenced".

There are a few ways I know of which this would occur.

It is possible the female would express the heterozygous version, whereas the male would need to be homozygous to show the mutation. This would become evident through line breeding.

It could also be that a female would express either or both heterozygous/homozygous and the male would express neither.

In either case, this infers the genes are being regulated by hormones, or other gene products that are turned on/off in female development either exclusively, at a different time, or to a greater extent than in males ("epigenetic effects".

Some genes may be turned off specifically depending if they are inherited from either the mother or father, this is called "imprinting" and is a type of epigenetic effect.

Something else that may appear to be this, but is quite different is termed germ-line mosaicism. A fraction of the male sperm, or female eggs, may carry a mutation that other cells don't carry (a very small or even large fraction), this would allow offspring to express phenotypes quite different from parents.

I know that with these possibilities it can be hard to uncover what is going on, but this is what we have to work with. Keeping really good breeding records is very important.

-----
steve

I see things otherwise. For me, "sex-limited" is a nerd who walks into a bar full of babes, "sex-influenced" is that same nerd spending all his money there... and still getting nothing

Lol.
Now, for real. I fail to see exactly how can a gene be influenced by hormones if when genes are created there are no hormones there yet (?). All creatures are sexless for the first days of life (or, in theory, all females)and when they develop to run on hormones of their own - not mother's - they already have a defined genetic structure. I would say things happen some other way... as if some genes rull out others. But i don't know for sure.

Ok, if you breed the male to a "normal" it will make the mutation... 50%. All of the expressed mutation are girls...

Then if you breed a normal to a female expressed gene carrier you make both expressed visual sexes.

Don't know what you get when you breed them together...

So far a visual hypo...

Weird..... Now have to see if there is a Super visual form...

Both sexes seem to express it visually the same.

Thanks.... Kev

>>Very good question Kevin, and the answer is yes.
>>
>> If a male carries the mutation, but never expresses it, then it would be called "sex-limited". If the male expressed it to a lesser degree, or on fewer occasions then it would be "sex-influenced".
>>
>>There are a few ways I know of which this would occur.
>>
>>It is possible the female would express the heterozygous version, whereas the male would need to be homozygous to show the mutation. This would become evident through line breeding.
>>
>>It could also be that a female would express either or both heterozygous/homozygous and the male would express neither.
>>
>>In either case, this infers the genes are being regulated by hormones, or other gene products that are turned on/off in female development either exclusively, at a different time, or to a greater extent than in males ("epigenetic effects".
>>
>>Some genes may be turned off specifically depending if they are inherited from either the mother or father, this is called "imprinting" and is a type of epigenetic effect.
>>
>>Something else that may appear to be this, but is quite different is termed germ-line mosaicism. A fraction of the male sperm, or female eggs, may carry a mutation that other cells don't carry (a very small or even large fraction), this would allow offspring to express phenotypes quite different from parents.
>>
>>I know that with these possibilities it can be hard to uncover what is going on, but this is what we have to work with. Keeping really good breeding records is very important.
>>
>>
>>-----
>>steve
-----
"Satan™" is a registered trademark of NERD, Inc. Any copyright infringement is punishable by ETERNAL DAMNATION and some other terrible stuff.

1 more thing. If you have breeding records, I would enjoy trying to develop a hypothesis. I don't need to know the mutation, just the breedings, sexes and which animals expressed the phenotype.
-----
steve

After reading the ? again, it seems simpler ---X-linked---- Males get the X chromosome from mom not dad. Girls get 1 from dad and 1 from mom.

Sorry for all the other BS. Cheers
-----
steve

Steve,

I would agree with you, that from Kevin's description it is a sex-linked (X-linked) mutation.

Although this is very common with birds, I have yet to see a x-linked mutation in reptiles. Which mutation is doing this Kevin?

Regards,
Jordan

Reptiles don't have the XY male and XX female sex chromosomes. Instead it's ZZ male and ZW female.

Ok. But besides alphabet choice here, i guess the priciple stays sort of the same (correct me if not so) I'm sure that a snake can't produce hormones prior to having a genetic code to even work with. So, it's a chicken and egg problem. During formation, the only hormones that the snake will come in contact with are female hormones (obviously, since the male's job is done and the mother carries from there on). But i'm no zoologist and i'm just speaking my mind out. I could be quite wrong.

Hormones are synthesized very early in development and essential for genetic regulation even in the blastocyste (approximately 40 cell stage). But yes, the hormones are encoded by genes, and as I pointed out, many other gene products (i.e. transcription factors) are important epigenetic modulators as well. Also, as you pointed out, molecules (hormones, transcription factors, mRNAs ect...) from the mother also mediate many effects on the offsprings genome. Any of these could influence the visually apparent phenotypes such as color and pattern. Thanks for the input.
-----
steve

I was thinking that they get the x chromosone from mom and that may be it... but I barely know this stuff....the REAL version of what is going on and would rather hear it from a person versed in reality.

Kev

>>After reading the ? again, it seems simpler ---X-linked---- Males get the X chromosome from mom not dad. Girls get 1 from dad and 1 from mom.
>>
>>Sorry for all the other BS. Cheers
>>-----
>>steve
-----
"Satan™" is a registered trademark of NERD, Inc. Any copyright infringement is punishable by ETERNAL DAMNATION and some other terrible stuff.

Hi Kevin,
If you want, drop me an email with the ratios, number of offspring produced, morph vs non morph, etc. I will sit down and work through this and see what we come up with.

Warren
-----
Dr Warren Booth / Director USARK
North Carolina State University
Department of Entomology