"Discus Genetics and Breeding Info and Discussion"

[James Yangzon]

There is no governing body spearheading any part of the discus hobby from what i have seen.

Is this also the reason why the 'naming game' is so popular with breeders? A fish with just a little difference in hue, will now have superlatives as its first name such as 'super dooper what have you'?

The discus breeding trade is for the most part secretive, and almost none that i have met will discuss the issue.

I presume this is the business side of it.

But none of the information is scientific, the discus is not important from that point of view, and from what i can tell scientific study will always be somewhat marginal.

Scientific research, unfortunately, for the most part is based on the interests of the funding agency. Is it possible that there will be an organization that might reach out deep in their pockets to fund research regarding color creation in discus? This will definitely clear a lot of confusion.

[James Yangzon]

It looks like scientific study is still in its infancy regarding interactions between the color cells, and we must infer information about other fishes and make deductions based on this.

Are there no study on cichlid in general Rod?

While i do accept that there appears to be several species of discus, to me i treat them like 1. They breed with each other and produce fertile offspring, and most aquarium specimens have been mixed together.

From the aesthetic point of view, hybrids can be tolerated. However, (not sure if this make real sense) hybrids which I assume existed decades already, may produce a mutant color gene and to understand how this mutant gene works, we go back to the wild form as our reference and we are now suddenly faced with the realization that our reference point is a mixed of of two or three wild forms.

[Rod]

Are there no study on cichlid in general Rod?

I don't know James.

From the aesthetic point of view, hybrids can be tolerated. However, (not sure if this make real sense) hybrids which I assume existed decades already, may produce a mutant color gene and to understand how this mutant gene works, we go back to the wild form as our reference and we are now suddenly faced with the realization that our reference point is a mixed of of two or three wild forms.

What i mean is the discus are so closely related to each other, that they breed and produce fertile young. This indicates that the genone is virtually identical to each other and for practical purposes we can treat them as one. Any mutation found, will be transferrable within the species, and this has so far proven to be the case.

[tomas_ch1]

Tomas,

Are you aware the you just redifined the Blue Diamond as a Dihybrid? I am not so sure this is the case at all, and still believe it is the result of a single mutated allele.


Rick

It was not my intention Rick. Maybe my English or my rashness. I still think BD is monogentic, nodyhybrid of those traits I was trying todescribe. I just wanted to compare it (BD) to ANOTHER “patternless” mutation we can see in Red covers/Virgin reds. I think they are different! Talking about “patternless” I refer only to those RC/VR types and I was trying to compare it with BD which is different (although without patterns too). Let’s use “BD” for blue diamond and “PL” for pattenrless of Red cover type.

Furthermore, patternless or near patternles fish occur naturally, I am not so sure this is a mutation at all.

Rick

I admit it occurs, but IMO it does not mean that it is not a mutation. You are pointing very precisely to the fact that patternless term is confusing and it may occur in many varieties. But again I am trying to focus on Red Cover type of loss of patterns and then I think we can take it as separate phenomenon. Btw let me remind you another of your educational crosses you bring on another forum (I realize it earlier and now it came to my mind again) http://newdaah.com/index.php?topic=11917.0 If you will consider patternless gene as dominant and your fish were both heteozygous for that PL mutation, you can have a clue for getting pattern fish from patternless parents. What is your opinion on such explanation Rick, is it possible that parents were hetero...? Does it fit to your other breeding experiments?



Thank you again not only for your educational crosses, but also for your kind and challenging comments.

Tomas,

I would also like to add, what I was alluding to in an earlier post. If we explain the blue coloration in the heterozygous BD cross's to be not a result of the heterozygous BD gene, but by some other mutation and or phenomenon, we are then in effect saying that the creation of a solid blue, patternless fish, similar in appearence to the BD is possible, and it need not have the BD gene.

Rick

I agree with your conclusion just do not thing that it will be similar or “the same blue”. It will be bluish (with bluish hue) because other chromatophores will be still visible too. In BD you see just iridophores and nothing else. But I don’t want convince anybody about that, it´s my 2cents and may be all wrong. You can be right finally that BD especially together with some other mutation (not against the wild type) can be semi dominant, may have stronger penetration in heterozygous combination etc. Here is another example of bluish hue in F1 of BD x leopard cross http://forum.simplydiscus.com/showth...-diamond/page4 Here the difference is that only some of them look like that, not the entire spawn. In other words there have to by some other BD heterozgotes not showing blue hue....

Again just an ideas. it is fine to chalange our views by different point of view,
Tomas

[nc0gnet0]

Tomas,

I would ike to add, that I really like the idea of you bringing the color producing organells into the discussion. This is an area seldom touched upon. When you add this, plus the inclusion of color distrubition through the dermal layering, only then can you start to get an idea what is actually going on. For those people that are reading the recent activity on this thread and shaking their head, it's really not as hard to understand as one might think.

Chromatophores are pigment-containing and light-reflecting organelles in cells. For the purpose of this discussion, they are in essence, what gives the discus their color. They are largely responsible for generating skin and eye colour in cold-blooded animals and are generated in the neural crest during embryonic development. (wikipedia)

Mature chromatophores are grouped into subclasses based on their colour (more properly "hue") under white light. they are:

xanthophores (yellow)
erythrophores (red)
iridophores (reflective / iridescent) (think "sheen")
leucophores (white)
melanophores (black/brown)
cyanophores (blue)



Some species can rapidly change colour through mechanisms that translocate pigment and reorient reflective plates within chromatophores. This process, often used as a type of camouflage, is called physiological colour change or metachrosis.Cephalopods such as the octopus have complex chromatophore organs controlled by muscles to achieve this, while vertebrates such as chameleons generate a similar effect by cell signalling. Such signals can be hormones or neurotransmitters and may be initiated by changes in mood, temperature, stress or visible changes in the local environment.

With a basic undestanding of chromatophores, and something called dermal layering many colors and shades can be developed. For instance a xanthophore layered on top of a cyanophore might give us a "green" look. When we start to understand that these color producing cells seem to occur in different areas/depths of the dermis often time one on top of the other (as Tomas alluded to) we can start to aprreicate how the color and pattern of a discus is formed. Also, when we start to look at the known mutations impact on these organelles and their distrubution, we can start to understand how and why a discus is colored the way it is.

[nc0gnet0]

Now if for a moment we back away from the discussion on the blue diamond gene mutation and take a look at the pigeon blood mutation in relation to what is happening with the chromophores, things can get interesting........

Many times the pigeon blood mutation has been described as the "breaking up of the stress bars" or something to that effect. To Quote Rod

Many think pepper is a modification from the mood bars. I remain sceptical of that!

I think the description is in general correct, however severly lacking in detail. I believe the stress bars are still there, but the melanophores that normally lie in the region where the stress bars are have been relocated, or "scattered" if you will. When raising young Pigeon blood fry, in early development, we can see strands, often golden/metallic in color were the stress bars should be. I believe these to be some kind of neurotransmitter (think electrical conduit or nerve). On a non pigeon blood barred discus when stressed, this area or region gets darker, and serves as a form of communication for the discus. But in order for this to happen, the melanpphores have to be present, if they have been scattered, as in the case of the pb, essentially what we have is a light socket without a light bulb in it.

I can go on to say that the the degree of scatter varies, and some times not all the melanophores have been redistributed away from the stress bar area. This is why, I beleive, we see some not so actractive pigeon bloods with partial stress bars, often in the dorsal region.

If we take this a step further, and assume that the pigeon blood mutation not only redistributed the melanophores, but impacted ALL chromophores (kinda broke the gentic code that had them locked in place), things really get interesting. By exposing certain chromaphores that had been previously burried under several layers of other chromophores, it allowed breeders to focus thier efforts on a particular color, and through succesive line breeding, allowed them to produce a particular color and give us the many varietys we have today. The colors were always there to begin with, just not as easy or perhaps even possible to manipulate.

Rick

[James Yangzon]

Importance of the Recently Caught Wildtype

I understand that the mutation aplies to all the three wild form. What I am driving at is that the best way to know how a mutated gene works, and we agree on this one Rod, is to contrast it to the wild type. (This should be coupled with the knowledge on how color is created on Discus, fortunately, recent posting of Tomas and Rick have started to touch on this.)

And this is why I am putting much emphasis on the importance of the wildtype, specifically the recently caught one (so we are sure it does not carry any recessive gene)

What should be done in IMHO is to cross all single gene mutations to the recently caught wildtype (recessives will take another generation to see the results) and assess the phenotype of the resultant offspring. There is so much confusion already maybe because we based our analysis on offspring that is a result of a cross between the monogenetic mutation and combination of single gene mutations. Imagine how many factors are already involved in this kind of crosses.

In other words, let us go to the basics. We can only isolate accurately the description we are looking if it is contrasted properly to the wildtype form.

[nc0gnet0]

I refer only to those RC/VR types and I was trying to compare it with BD which is different (although without patterns too). Let’s use “BD” for blue diamond and “PL” for pattenrless of Red cover type

.


I know what you are saying, but I stop short of feeling comfortable using your example, even if it is just for explanation purposes. My reasoning for this is simple, we have certain KNOWN mutations, they generally follow along mendall's principles. And then we have these OTHER alledged mutations, that most often are not mutations at all, but rather just the carefull alignment or as Rod calls it the reshuffling of multigenectic traits, producing a unique phenotype. Such examples are:

Spotted gene
Ring gene
Ring 'O" gene

I think the mislabelling of these traits is a great disservice to the hobby and leads to even more confusion. In order for us to use your "PL" mutation, we have to first determine if is a mutation at all (which I don't beleive it is). Many degrees of pattern are found in non mutated wild type discus, they can go from complete lack of pattern to full pattern (ofter referred to as Royals), to allow for the ones that are completing lacking in pattern to be explained my making a leap and saying they have a genetic mutation, wouldn't we have to do the same for the ones that have complete pattern as well?

[nc0gnet0]

Now if I may, let me have you look at the BD mutation from a different angle. Not saying this is the case, just an hypothesis......

What if the Blue Diamond isn't patternless at all? What if the mutation has somehow efected the developement of chromopores in such a way that all are expressed as either cyanophores and irridaphores? Then we have a fish in which the appearence appears to lack pattern, but only becuase we were painting a picture with just one color?

Rick

[zimmjeff]

One of the best discussions I've seen on SD. Now if I only understood more than 2 words. Jeff

[James Yangzon]

One of the best discussions I've seen on SD. Now if I only understood more than 2 words. Jeff

Good day Jeff;

I know where you're coming from, and I know Rod, and the others, are doing their very best to communicate a technical subject in layman's terms.

Let me contribute some:

Phenotype - simply means physical appearance, can be understood easily if contrasted to the term genotype
Genotype - means the genetic composition of the fish

Example: a discus pigeon blood can be said to have a phenotype or appearance of a pigeon blood. However if ask what is its genotype, it could be PB/bd, meaning pigeon blood split blue diamond. Blue diamond being recessive it cannot be expressed or its appearance is 'hidden' unless two chromosomes carry the bd gene.

Let's stop to these two terms first. We will take it one step at a time. Next we will try to explain the term 'dominant' and 'recessive'. However, if you feel like it, there is also a thread here posted by Megason. The topic is 'How to identify an allele', it is still a bit technical but it gives the basic quite well.

God bless.

[tomas_ch1]

Now if for a moment we back away from the discussion on the blue diamond gene mutation and take a look at the pigeon blood mutation in relation to what is happening with the chromophores, things can get interesting........

Many times the pigeon blood mutation has been described as the "breaking up of the stress bars" or something to that effect. To Quote: Rod Many think pepper is a modification from the mood bars. I remain sceptical of that!

Rick

I would be very happy if Rod could join in, but I thing I know where his skepticism comes from. I share it. I mean I do not believe that it comes from “stress bars”. Otherwise I think you hit the nail with interaction issue in chromatophores and spreading our portfolio to PB would be, well ....interesting......


In my understanding defect in PB does not relate to stress bars itself but to all melanophores in basic layer of dermis. In other word, all melanophores in lower layers are affected in their function and missing stressbars are just one of the results.


I never did it but if I should try to describe PB, I would try to something like that:


PB is defect in basic layer of melanophores causing strong reduction of number melanophores in all discus body (including stress bars formation), but retaining the function of those who survived. Xantophores and Erythophores function remains unattached probably, and are even more visible with lack of darker background, what allows further cultivation of PB based forms for red/yellow or orange if we add genes with these chromatophores. Iridophores seems to be touched in appearance of lighter violet to white, but its possibility to form patterns remains uninfluenced.


And do not say to me it sounds horrible – I can see it myself .... Now, let me explain may way of thinking

• - We all know, that base color is touched from smallest fry in PB. Even fry can be distinguished from wild types by lighter appearance – it means not only stressbars, but also other parts of tissue are affected. Melanophores are lacking from the beginning and in all the body.
• - BD can darken little bit and pepper especially keeps normal melanophores function (hormonal or environmental reaction) – it shows us that defect in melanophores is not complete (in Albinoss for example, we can see complete lack of melanin and no melanpohores at all).
• - We all know that PB is base for tens of other PB based forms – so selective breeding is possible and shows that yellow/red/ orange cells are deveolping normally.
• - PB in original forms and many of its hybrids keep patterns. Evethough As we know that there are two main sorts of covering patterns (i.e. turquoise marking and red dots) we can see that PB can form "wild type parrents" but their shape and colors differe little bit
• - And now the most secret iridophores. I believe that they are present in PB, but because of lacking melanophores below them, their ability of iridescence and reflection is touched somehow and ability to reflect light is shifted to higher wave length.

That’s my view, but I obviously we cannot demonstrate it without scientist research just as i cannot exclude your (Rick) proposal that mutation impacts directly somehow also other chromatophores directly not through interactions with each other (these interactions seems to be crucial for pattern formation) – especially iridophores.
Tomas

[tomas_ch1]

.


I know what you are saying, but I stop short of feeling comfortable using your example, even if it is just for explanation purposes. My reasoning for this is simple, we have certain KNOWN mutations, they generally follow along mendall's principles. And then we have these OTHER alledged mutations, that most often are not mutations at all, but rather just the carefull alignment or as Rod calls it the reshuffling of multigenectic traits, producing a unique phenotype. Such examples are:

Spotted gene
Ring gene
Ring 'O" gene

I think the mislabelling of these traits is a great disservice to the hobby and leads to even more confusion. In order for us to use your "PL" mutation, we have to first determine if is a mutation at all (which I don't beleive it is). Many degrees of pattern are found in non mutated wild type discus, they can go from complete lack of pattern to full pattern (ofter referred to as Royals), to allow for the ones that are completing lacking in pattern to be explained my making a leap and saying they have a genetic mutation, wouldn't we have to do the same for the ones that have complete pattern as well?

I see your point. Too many simplyfication and generallization is not good and may be missleading. I wolud like to know what Rod had in minde when he mentioned patterless in his earlier post with list of mutations.

[tomas_ch1]

Now if I may, let me have you look at the BD mutation from a different angle. Not saying this is the case, just an hypothesis......

What if the Blue Diamond isn't patternless at all? What if the mutation has somehow efected the developement of chromopores in such a way that all are expressed as either cyanophores and irridaphores? Then we have a fish in which the appearence appears to lack pattern, but only becuase we were painting a picture with just one color?

Rick

Oh YES!! that is great and i like such view. I think it fits.

Good night(day) for today
Tomas

[DiscusLoverJeff]

By far the best discussion on SD forum. As Jeff mentioned about understanding the words and terminologies, its just a pleasure to read and see such great theories, ideas and knowledge being shared for us all to try and understand.