A New Tool for the Guppy Color Investigator
Full Platinum with the "Material" Gene
I often think of the investigations I do into guppy color and pattern as more akin to sleuthing than scientific research. An investigator uses all kinds of evidence to solve a case, not just the results of scientific experimentation or research in the journals. To the investigator forensics is just one of the tools employed to solve a mystery, although it is probably the most accurate and produces results that are hard or impossible to dismiss. But if you are a guppy hobbyist color investigator, a lot of time is spent on your feet talking to other people or hunched over at desks on the phone or the Internet.
One of those cases I have been trying to solve for the past decade or so has been the genetics of yellow platinum, attributed by Japanese breeders to the mysterious "material" gene. One of my informants in Taiwan told me long ago that he thinks the English word "material" is a bad translation. The word "shining" is probably better he opined. In any event it is the gene that Japanese breeders ascribe to the Mikariff. It is supposed to give the Mikariff it's shiny metallic yellow color. It is also supposed to be the gene involved in Japanese Full Gold genetics and other "yellow platinum" strains. Even the Schimmelpfennig Platinum strain might involve the material gene.
I have been calling this gene the Mg (Metallic gold) gene. It is also found in the Full Platinum, like the guppy you see in the above picture. I was not sure until today if Mg was the same gene as the Japanese material gene.
The Mg gene has some special characteristics that have been bugging me for the past five years. I have been in the position of a detective that has a long term unsolved mystery on his hands. Bits and pieces of the mystery have fallen into place, but the mystery remains unsolved.
If you look closely at the above picture you will notice that the front half and back half of the male have different colors. The peduncle has a shiny metallic yellow color. The front sides are white metallic. I believe this guppy also has the white saddle gene, which normally covers the dorsal area with white. In this case the dorsal appears to be metallic gold.
Last weekend I purchased some guppies from a pet store chain to investigate Mikariffs further. When examining the reflective, iridescent or refractive colors of guppies you cannot rely solely on making determinations looking into tanks under tank lighting. You are best to put your subjects into a photo tank and light them from the front. A high resolution image on a computer screen under correct lighting is the goal. Only then will your observations be accurate. It also helps to put them through Photoshop color correction.
Pet Store Guppies
Both the pet store guppies have the Mg gene (a.k.a material gene). It is strongly expressed at the juncture of the base of the caudal fin and peduncle as a yellow metallic area. The females can express it as well, as you can see in the top picture. She tends to show it strongly in the peduncle, but it can also appear as metallic areas in the front of the body.
One piece of the puzzle that fell into place several years ago is that the so-called Platinum phenotype (yellow metallic) required the incorporation of the half-black gene. That is why you see a difference in the color of the Full Platinum in the peduncle. It is even more obvious in the Tequila Sunrise with the red fins in the above picture. But for me that just deepened the mystery. It was like finding a major clue but not knowing where it would lead me. Why yellow in the peduncle and white in the front of the body? I could not make sense of that clue.
It appears that the Mg gene also makes the dorsal area metallic gold in an area usually attributed to the white saddle gene. And it appears black Moscows with the Mg gene were capable of displaying whole body metallic color.
Silverado. This is a Blue Moscow with both the Magenta and the Mg gene.
But why is the Silverado silver and bluish colored? Another mystery.
I should say as an aside that the Mg gene is not the Stoerzbach gene as many people, particularly European breeders believe. That is one of those suspect genes that can be eliminated as a "perp." I was able to determine this by combining an Mg strain with a Stoerzbach strain. My Chiasson Full Reds carried the Mg gene. When I incorporated the Stoerzbach gene into the strain, you can see that the two genes are mutually exclusive.
Full Red with both the Mg and Stoerzbach gene
Compare that to a Full Red sibling. This is how the Mg gene is expressed when you take the Stoerzbach gene out of the mix.
Full Red with the Mg gene. No Stoerzbach gene!
Another piece to the mystery that nearly drove me crazy was the occasional appearance of a very different phenotype in crosses involving the Mg gene.
Metallic Gold Phenotype
The Metallic Gold phenotype looks quite different to the previous guppies. The gold metallic color is spread evenly over the body. It does not have a white component. In fact I named the gene after this phenotype because somehow I thought it's appearance fundamental.
I suppose it might be true that good scientists are good investigators, and not all theories spring out of experimental data but rather arise out of hunches and seemingly unrelated phenomena.
I have been thinking recently about the relationship between sex-linked genes (X or Y) and autosomal genes. In the scientific literature I had come across two references to the relationship between sex-linked genes and autosomal genes but they were vague. (I will discuss this more thoroughly and give references in the Color Manual.) My own experiments with the Midnight and Onyx genes showed that the half-black gene depended on autosomal genes for its color. An example is the Pingu, which is a guppy with both the Pink mutation and the half-black gene. It's peduncle is pink instead of black. On the Moscow the pink mutation is expressed as white areas in the front of the body.
So here is a case where I think the half-black gene is actually given the wrong name.
It's color is determined by an autosomal gene.
And then last week I was in an email exchange with another guppy breeder about the nature of Full Red genetics. He kept insisting that genetic analysis showed that Full Red was sex-linked. I kept insisting that it had to have an "autosomal component." I was intuitively following a hunch that Full Red was not simply due to a sex-linked gene. I suspected that its very color might be due to an autosomal gene. In fact there is a lot of Full Red breeders who think it is autosomal.
And then this morning, while going over my research for the Color Manual, I came across this posting from an old Singapore Guppy forum, a message by the breeder Patrick under the pseudonym Spider. I am not sure, but I think this might ultimately derive from a Chinese translation of the work of Yoshiki Tsutsui, the famous hobbyist guppy geneticist.
"Material" gene is the term Japanese used for metallic or Micariff gene. What they want to describe is probably "element" or source of the displayed metallic phenotype.
It is probably the same as Stoerzbach metal solid(ss) gene that they're refering to
According to the Japanese, "Material" gene is the autosomal recessive gene for body color. Similar to albino.
The "Material" phenotype will only appear if the Y link chromosome have a "complimentary" gene(in my term, it mean you need certain conditional gene to activate the phenotype).
The conditional gene for example can be the Y link dominant snakeskin(Cobra in asia) gene or the half black(Tuxedo in Asia). For the case of HB Y link cross you'll only see the "Material" phenotype on the HB region
I hope the explanation is clear enough. Most Japanese are referring to this gene when they say that their fish have platinum gene. Example of Japan strain with this gene are Medusa, Galaxy, Full Gold , etc.
I read this info from Aqua Farm magazine FYI.
Patrick aka Spider
http://sgguppy.com/index.php?topic=74.msg378#msg378
I guess I never quite understood the implications of this posting when I first read it until I had the background knowledge to fully appreciate it. I am not sure I agree that the sex-linked gene has to be Y-linked to produce the phenotype, but I am willing to keep an open mind about it. There is some evidence in my crosses for this theory. In any event the author of the Aqua Farm magazine identifies the Mg gene as autosomal and says it needs a sex-linked gene to be expressed. That is the important point.
Why do I think Full Red gene is a sex-linked and autosomal combination of genes? All the mutations affecting red are autosomal. The Asian Blau and European mutations are autosomal. The Pink mutation, which also suppresses red is autosomal. The Magenta gene, which changes the color and distribution of red is autosomal.
And yet simple Mendelian genetic analysis will show that the Full Red gene is sex-linked. It will also show that the half black gene is sex-linked. But just as the color of the so-called half-black gene is modified by autosomal genes, I believe that the color of Full Red guppies is determined by autosomal genes. It is the pattern of expression that is sex-linked. That is ultimately what the author of the Aqua Farm article was trying to convey. If you dig around in the Guppy Designer forum you will see that I have explored this idea before. I called the pattern of expression a "zone." Since the word "expression" has a more established biological meaning as the production of a gene transcript and its translation ultimately into a protein, and the word "pattern" refers to the position of color cells in the skin, I think I like "pattern of expression" better.
It just so happens that I got the idea of zones from Patrick aka Spider's thread about the Full Red gene. He thought Full Red is due to a number of sex-linked and autosomal genes that combine to produce the solid red phenotype. I happen to now disagree with that characterization, if it suggests that the color of the guppy is painted on by different red genes. Instead, I would say that there is an autosomal network of red genes whose expression on different parts of the body are determined by local sex-linked genes. In other words the Full Red phenotype is due to the pattern of expression imposed on autosomal red genes by sex-linked genes. That is the explanation for the white metallic front and yellow metallic back of the Full Platinum guppy.
Well, that is the working theory, that red color on the guppy is always due to two different genes, one sex-linked and the other autosomal. I think it is a more plausible theory than a view that says that the full red phenotype is due to either a sex-linked or autosomal gene...given the evidence.
I know I am running two parallel cases here trying to determine if the same "perp" is at work. But there are so many parallels here!
Just as there has been confusion about whether the Full Red gene is sex-linked or autosomal, there has been a similar confusion in yellow platinum discussions. The color of Mikariffs, Full Golds, Full Platinums and other yellow metallic strains is often described as "yellow platinum." And the gene is said to be due to the Platinum gene. The Platinum gene has been found to be sex-linked. And yet here we have Tsutsui ascribing the actual color of the Platinum gene to an autosomal gene called "material." It turns out there are two genes involved, one dependent on the other for its expression as a pattern on the body, one sex-linked and the other autosomal. This is probably the case with the Full Red phenotype.
In fact I suspect this is also the story about the red spots on wild guppies. The autosomal red genes are expressed as red spots on wild guppies by Wingean highly Y-linked supergenes. Since the red spots cannot be transferred to the X chromosome through crossover, this is indeed seems a case where the expression of an autosomal gene is modified by a Y-linked gene. Maybe Tsutsui's speculation about the Material gene has a wider application.
So what do I make of the fact the Full Platinum has two different colors, front and back. And what do I make of the fact that the Mg gene has the potential to be expressed as silver (as in the Silverado above) or yellow platinum (as in the Full Platinum above)? The theory must be that the expression of the Mg gene is indeed modified by other genes. The fact that the Full Red shown above has a yellow area at the base of its peduncle is another case where the Mg gene's expression is modified. I cannot tell if it's expression is confined to that small area at the juncture of the caudal fin and peduncle or if the Full Red color is enabled by the Mg gene.
Another case in point may be the Schimmelpfennig Platinum strain. Is it too a combination of a sex-linked gene and the Mg gene? I am not sure if an X-linked version of the gene has been demonstrated. But in crossing a Full Platinum strain with the Schimmelpfennig strain I created a new phenotype that appears to combine on the body to create a Full Yellow guppy that I call "double yellow."
Double Yellow, combining the Schimmelpfennig Platinum and Full Platinum genes.
Is this an example of the same autosomal gene (Mg) expressed by two different sex-linked genes (Schim and Full Platinum) in different areas of the body?
It is possible that pigment biosynthesis is autosomal whereas as the expression domain of those autosomal genes are controlled by sex-linked genes. A possible biological reason? The male guppy uses color to attract females. Red spots play a major role in signaling fitness to females, so it seems likely that the mechanisms for manipulating red spots should be Y-linked. And since yellow color cells are virtually identical to red color cells, differing only in the relative amounts of red or yellow pigment, it is likely yellow color is under the same regulation. The same may be the case for black spots or patterns...indeed all the secondary sex colors that appear on males and not females.
Only further investigation will reveal what the biological basis for this relationship between sex-linked and autosomal genes will turn out to be. I have some very good ideas. But I will leave that to the Color Manual. (Hint I think it may all come down to black pigment genetics.) That is where I connect all the dots. Meanwhile I have a brand new paradigm for investigating guppy color: a combination of sex-linked and autosomal genes that defies simple Mendelian analysis. I thought I was pursuing a single "perp," masquerading as a sex-linked gene. Turns out I have been pursuing a conspiracy.
Note that I am not saying all color genetics in guppies conform to this new (to me) model. Obviously the colors a guppy is born with, composed of yellow, black and iridophore color cells, do not conform to this model since the sex-linked colors kick in as the sex hormones begin to flow in the blood. (In fact in the mature guppy there is at least two different populations of black color cell types under different genetic control. This may be true of yellow and iridophore color cells as well. Only red color cells seem to be entirely sex-linked, as guppies are not born with this color.)
Albinism is an example of a mutation that does not conform to the two gene model, although it is known there are up to eight different genes involved in melanosynthesis. In fact most pigment biosynthesis mutations do not seem to conform to the model of a sex-linked and autosomal combination. It seems secondary sex color patterns fit the model best. Interestingly, the snakeskin pattern is another case in point. It also modifies the Mg gene, creating the actual Mikariff phenotype, a whitish full metallic guppy. (The Tequila Sunrise and Full Platinum guppies involve the sex-linked half-black gene.) The snakeskin pattern is changed into a blue metallic pattern by the autosomal Magenta gene.
So where do I go from here? Where is my investigation going to look next?
There is another phenotype that I talked about in an earlier blog that is germaine to this ongoing mystery. It is the non-red anomaly that showed up in a Full Red cross that involved the Mg gene.
Blue Anomaly, the result of a Santa male X Full Red female cross.
This guppy has lost its red color altogether. In the F2 of the cross between this male and his sister, I got only one male in the entire drop with a similar phenotype. That is very puzzling. I am backcrossing him to his daughters to generate more data. The ratio of young that appear to have his phenotype will be very interesting. It might just might provide the forensic evidence for his genotype and ultimately the two gene theory. At least now I have a new model of guppy color genetics that will help me figure it all out.
Meanwhile I will make this parting remark. The Blue Anomaly I wrote about in an earlier blog ("A Universe in a Set of Fins") may in fact share specific genes with the Silverado pictured above. And there are other possible similarities with other phenotypes, like the Pied guppy I wrote about in yet another blog ("New Pied Beauty Strain"). Just connecting the dots...
Comments
In my cross with a Silverado male and Full Red female the F1 males look a lot like the "Full Red with both the Mg and Stoerzbach gene" you posted. The Caudal tails are smaller and with less red but the Mg trait is evident and the full metal body as well. If I don't have the Stoerzbach gene what would that metal body? I am guessing that is the Asian platinum
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