EBJD

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jakeca77 said:
If people have been successful at spawning EBJD pairs but the fry did not survive past 10 days then I would think that the offspring must be homozygous for a lethal trait. It could be something similar to phenylketonuria (PKU) or any of the many other genetic disorders in humans that would kill or cause developmental defects in newborns without proper treatment. The offspring may not be producing an enzyme or protein correctly, causing them to die. We will never know unless somebody sequences and does a thorough study of the regular JD genome and then compares it to that of an EBJD. Somebody could do a necropsy on the dead fry to determine why they died... If that is even possible on such a tiny undeveloped specimen?? Anybody know a fish pathologist?
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Good point, what I was trying to get at in better words. Thanks.

In regards to a mutation being a cause for "weak genetics"..... . You have to understand that mutations are not always a bad thing. They can be a good thing, it just depends. Mutations could lead to death or it can lead to the evolution of a new species.
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Of course. But unfortunately it seems this "mutation" if it is such is not a good thing, unless we can separate out a cause for the lethal portion.

Regarding the hybrid study - if it was done. I wouldn't trust any kind of genetic study that was performed to determine whether or not the fish was a hybrid that hasn't been undertaken within the last couple of years. Case in point, for years, the experts were saying that humans had not hybridized with neanderthals. There are now studies out that say that we are. So as the technology impoves and we learn more, the information can change. The fish don't look like hybrids to me but who knows. I am no expert. The fish breeder did not share his notes or work on how the strain was developed. That in itself might make some ask if it is a hybrid. Most breeders keep good notes on what they are doing, these notes would answer a lot of questions. If it wasn't a hybrid then why the secrecy? The EBJD is supposed to be naturally ocurring but how many hobbyists that are just breeding 2 regular JDs together are lucky enough to find one EBJD? I can understand why a breeder that is culling his fish might discard them, but the home hobbyist that is just trying to raise some fish for fun? Somebody should see them? The determination of hybridization by using genetic testing is still going to be difficult since we have no idea what the other progenitors could be in this strain.
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There is a thread here on MFK that disintegrates this theory. It is translated from Spanish and basically what is deduced from said study is that there is no conclusive evidence as to what happens with EBJD x EBJD fry, and only states that "fry" in general were raised. It also has no evidence of successful rearing of pure EBJD fry, along with many other "red flags" so to say. Very unstable study done. Plus, Jeff Rapps has DNA evidence so I hear of the maternal EBJD being purely from JD bloodlines, but no one knows on paternal DNA. Hybridization is possible, but mostly unlikely with the loose evidence given.
 
Well, I will try this again....had a bunch typed out and had computer crash.

First. There is no way to "change" a gene. It is what it is. Second, the gene itself is NOT the problem. If it was, there would never be a blue Dempsey. Third. We cannot compare this to a human genetic disease; they are not analogous. If there are physical "issues" associated with a gene, they are always there and cannot be changed.

I am convinced that the blue color is a single, simple recessive gene. I am also convinced that this is a spontaneous mutation and not the result of hybridization. My logic here is that because it is a single gene and this color doesn't occur in any other species (to my knowledge) it almost has to be a mutation. Transfer of genetic material from one species to another can have unexpected variances, as seen in Platy/Swordtail hybrids but it is uncommon.

Ok, some wild possibilities:

The homozygous blue parents cannot produce (or do) something that the fry need to survive.
test-foster some babys

A second lethal gene is involved. Just don't think this is likely, or it would have been bred out by all the outcrossing.
test- do a bunch of breeding and RECORD all numbers for 3 generations

The blue fry cannot produce (or do) something they need that either non-blue fry or parents provide.
test-try raising a bunch of fry singly, in individual tanks. Any blues that survive disproves this idea.
 
Hm, okay. I didn't think of it as the gene of "EBJD" being the lethal gene, so that is insightful. Why not compare to human genetics? If there are physical issues with the gene that will always be there, maybe that is the problem?

I am convinced that the blue color is a single, simple recessive gene. I am also convinced that this is a spontaneous mutation and not the result of hybridization. My logic here is that because it is a single gene and this color doesn't occur in any other species (to my knowledge) it almost has to be a mutation. Transfer of genetic material from one species to another can have unexpected variances, as seen in Platy/Swordtail hybrids but it is uncommon.
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I 100% agree with this. Always have.

The homozygous blue parents cannot produce (or do) something that the fry need to survive.
test-foster some babys
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Has been suggested but haven't seen it done. Would be a good experiment.


A second lethal gene is involved. Just don't think this is likely, or it would have been bred out by all the outcrossing.
test- do a bunch of breeding and RECORD all numbers for 3 generations
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This is my theory, as previously stated.


The blue fry cannot produce (or do) something they need that either non-blue fry or parents provide.
test-try raising a bunch of fry singly, in individual tanks. Any blues that survive disproves this idea.
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I have personally thought about suggesting this option, because I was curious if perhaps there have been no successful attempts due to aggression on a fry to fry basis or the parents just eat them for some reason, thinking they are mutated. I would love to give this one a go.
 
The reason I don't think it should be compared to a human (or any species) genetic disease is this;

Adult, healthy, reproductive adults exist that are blue. There seems to be no deleterious effects in the adult form.

Healthy (though stunted), happy blue fry exist with no deleterious effects other than slow growth.

With the exception of blue, new-hatched, fry from specific breedings there are no problems.


Perhaps a side effect of the blue gene is a PREDISPOSITION to susceptability to a second problem; whether genetic, environment or nurture is the question at hand. I don't consider genetic predisposition a genetic disease. That position is of course arguable!

Please understand that I claim no first-hand knowledge of this color of JD! But I do have a firm handle on breeders genetics and very much want to solve this problem. Hoping to buy EBJD tomorrow and get my hands in the fray!
 
^ another thing prevalent with some adult blues is bizarre body and head shape. Having one grow to an adult and not have some sort of deformity is uncommon.
 
Gonna work through some math here to show why I don't think it likely to be a second gene.

Won't bother with compound punnet squares, just accept my numbers or redo them!!

Let's start with a pair of EBJD's. They are both homozygous blue since we have previously assumed this to be a recessive. Let's presume for this exercise they carry a lethal, recessive, UNlinked gene.

100 % of the fry will be blue. 25% will be dead due to homozygous lethal. 50% will be blue carrying the lethal gene. 25% will not be carrying the lethal gene and therefore have escaped the evolutionary hiccup. As many people that have tried these crosses that can't be it or we would have flown right by the problem- likely without even knowing it existed.

Ok. Let's add linkage. If all blue gene chromosomes also carried a recessive lethal, we could never have blue fish, so it is virtually impossible for ALL EBJD's to be homozygous blue/lethal. So let's make up a number to play with; let's say that 50% of the EBJD gene pool is linked to a lethal. The crossover rate in this situation is irrelevent.

So our new pair is thus; blue-lethal//blue-+ . Both fish have this genotype.

100% of the babies will be blue. 25% will be dead. 50% will be carriers of the lethal factor. 25% will be clean ready to improve the world.

Since it only takes ONE non-lethal fish being bred to produce 100% live fry, this situation is highly unlikely due to the presumably large numbers of attempts that have been made.

For those paying attention, there was no mathmatical difference between being linked or not! There WOULD be a gene pool mathmatical difference, but again; it only takes one fish to be non lethal to find the path home.

This cannot be the issue.

Note: the only way to get 100% dead fry with this scenario is for one of the parents to be homozygous lethal.....which makes it dead.
 
Hmm. Good points. Now let's throw something completely crazy out there and say if it were a lethal gene perhaps there is a side effect that causes aggression, causing the lethal fry to be aggressive to healthy fry, and as we know the regular ebjd are pretty docile. However I highly doubt this is feasible at this young age, its a thought. That is why I would like to see someone do a separated fry experiment.

Otherwise im lost but open to more ideas...not sure why this happens at all :(
 
Just a few things.

One more point on the hybrid suggestion and I'm done with it as I would think that even if it did come from some hybridization in the past, the actual trait is recessive in the population in question. Some have observed that some of the colors and patterns in EBJD resemble those of texas cichlids. Agree or disagree? I dunno, just putting that out there.

The reason I mentioned human genetic diseases was because it gives people something to relate to and although they are not analagous, there could be something comparable going on. Especially when it comes to survivability of EBJD x EBJD fry and genetic problems that arise from inbreeding.

Also, it has been observed that even juvenile fish are prone to die all of a sudden and as was mentioned by Bully Fish, the adults tend to have physical deformities. My own EBJD started out looking like a perfectly healthy fish but as an adult he is blind in one eye and has a crooked mouth. The suggestion that all adult EBJD are perfectly healthy is not true.

The suggestion of outcrosses to increase diversity in the fish has been suggested as a fix for some of the problems that arise from inbreeding. There is only one problem I see with this, and that is that we are assuming there is a high degree of diversity in the domestic population of fish we have on hand to use as breeding stock. There may not be and it is possible that some wild stock might be needed to help out in this area - assuming there is much diversity there as well...
 
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