# Labeotropheus Fuelleborni chalo



## cjacob316

so i've been growing a large group out, at first they were all pretty grey, some striped some not

now I have one obvious standard male with a nice pretty yellow color and what look slike a sub dom male that has a little yellow to him

the rest have sort of a mottled/OB look to them

I know a lot of labeo females tend to be OB, but does anyone know if males of this varient are ever OB?


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## 24Tropheus

I believe Chalo is just a mispelling of Charo - as I cannot find any Chalo on a Malawi map. Charo is located north of Kakusa and South of Gallireya Reef/Chilumba.

And should look like this maybe.
http://www.cichlidenareal.ru/wiki/index.php?vid=3744

All the best James


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## cjacob316

looks about right, sort of went through all of this when i first bought them, just couldn't find anyhting on chalo or charo at the time, so i have kept the name the seller used


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## Kanorin

> I know a lot of labeo females tend to be OB, but does anyone know if males of this varient are ever OB?


In every species with OB females that I am aware of, there exist a small percentage of OB males (usually about 1%) as well. This happens because the OB pigment gene (which is linked to the female sex chromosome in mbuna) has a small chance (~1%) to cross-over onto the male chromosome.

I'd bet that if you breed them enough you will eventually get an OB male.


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## cjacob316

pretty sure than some labeos never have OB males, despite all females being OB, but i could be mistaken


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## why_spyder

I think I'm with *Kanorin *- as long as OB females are present in the species, there is a chance of OB males appearing. Now if you are just working with a pair/small group, you may never get OB males to show up. I could be wrong (since I'm not real strong in genetics) but it might be that you need to have offspring of an OB male (even if it is down the line) in your breeding group to get OB males later on.


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## Kanorin

You shouldn't need any OB genes in the male line for the chromosomal crossover event to occur. In this case, the genetic material on the female chromosome (the OB gene) switches onto a male chromosome in ~1% of the female's eggs.

An OB male would pass on the OB gene to 50% of his male offspring. From what I understand, the OB trait is usually dominant, so I don't think a male can be a "carrier" of the OB gene without showing it.


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## why_spyder

So the standard male _Labeotropheus fuelleborni_ Katale males I get from my OB X OB cross aren't carriers? Then how did the standard male that produced my OB male do it?

I was under the impression the OB gene was recessive....


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## cjacob316

ok so you're telling me there is an ob male trewavasae zimbawe?


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## 24Tropheus

This article may help you guys to agree.
I think it is a little more complicated than anyone here is as yet saying.
Sex determination in these guys is not down to whole chromosomes but individual genes. Thus classic crossover across sex chromosomes does not occur to get a male OB. Just two tightly linked genes need to become separated (by crossover or mutation), or a more dominant sex determining gene could come into play (not yet found but I would not be surprised if it was). Yep OB are dominant genes (yep there is more than one) I think usually linked to predominantly female determining genes.

To avoid confusion I think it better to give the link than try and explain this (understanding subject to recent changes using DNA techniques I think) and I have prob just confused you more. 

http://www.cichlidnews.com/issues/2010a ... somes.html

All the best James

PS Paper for those interested.
http://hcgs.unh.edu/staff/kocher/pdfs/S ... n2003b.pdf


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## Kanorin

why_spyder said:


> So the standard male _Labeotropheus fuelleborni_ Katale males I get from my OB X OB cross aren't carriers? Then how did the standard male that produced my OB male do it?
> 
> I was under the impression the OB gene was recessive....


I'm in the midst of getting my PhD in molecular biology, so I've been curious about the inheritance of the OB gene and have done some research. Prepare yourself for a long read.

My information is based upon my readings of these two recent papers:
"MULTIPLE INTERACTING LOCI CONTROL SEX DETERMINATION IN LAKE MALAWI CICHLID FISH"
and
"Sexual Conflict Resolved by Invasion of a Novel Sex Determiner in Lake Malawi Cichlid Fishes."

Do you know how in humans, males have an X and a Y chromosome and females have two X chromosomes? Most malawi mbuna follow this rule as well, however a few species - including Labeotropheus Trewavasae/Fuelleborni and most of the Metriaclima species which have OB females, have it reversed. Biologists call this a "ZW" system of sexual inheritance - males have two copies of the Z chromosome (ZZ) and females have one copy of Z and one copy of W (ZW). The OB gene is a dominant pigment gene that is usually only found on the W chromosome - thus why predominantly females show the OB patterning. Males lack the W chromosome and thus do not have the OB pigment gene (true 99% of time).

So how do we get marmalade cat males if the OB gene sits on the W chromosome and males are ZZ and females are ZW?
When a female is producing eggs, each egg gets half of her genetic material (so that when combined with sperm, the offspring has 2 copies of each chromosome and gene). But before the genetic material is split in half, there is a phenomenon that occurs that is called crossing over (or synapsis). Basically, each pair of chromatids swap a small percentage of their DNA sequence. In the case of an OB female Labeotropheus, her W chromosome can swap a little piece of DNA with her Z chromosome. Apparently, there is roughly a 1% chance that this swapped piece of DNA ends up including the OB gene. The result of this is that the OB female produces an egg with the OB gene on the Z chromosome (so this egg is destined to produce a male offspring).

This marmalade cat male offspring has one copy of the Z chromosome (from his father) that is normal - we'll call it Z(bb) and one copy of the Z chromosome - we'll call it Z(ob) (from his mother). He can then pass on that Z(ob) gene to 50% of both his sons and daughters (remember, he has one normal Z(bb) gene). This means that if he were to mate with an unrelated OB female, 50% of his sons would get the Z(ob) gene and show the OB trait, and 50% of his daughters would have an OB gene on both of their chromosomes. These daughters, who are Z(ob) W(ob), when mated with an unrelated male, will have 100% of her male offspring with the OB gene (marmalade cat males).

Now if a Z(ob) W(ob) female is mated with a Z(ob) Z(bb) marmalade cat male, 100% of the males will be marmalade cats. 50% of those males will have two copies of the OB gene - they will be Z(ob) Z(ob). Such males, when mated even with unrelated females, will produce marmalade cat male offspring 100% of the time.

Thus, in just two generations, you can form a mating colony that will yield 100% of males as OB "marmalade cat males."

Cjacob, I'd be willing to bet that there exist the genetic potential for OB males for every collection point of Labeotropheus. You'll just need to breed them until you get that lucky recombination event to occur.

*Edit: 24Tropheus is right that sexual determination is a little bit more complicated than I explained above. There is not a single chromosome that houses all the male genes or all of the female genes. Rather, it's a group of tightly linked genes as he says. However what I outlined as far as the inheritance of the OB gene is still valid in this scenario. I was just trying to simplify things a little so as not to completely lose everyone.


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## cjacob316

well I hope for my sake that all of my ob fuelles are females. alternatively i hope, some day, I get an ob male from any of my labeo species


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## 24Tropheus

Thanks. What I find interesting is why the OB genes became linked to female sex genes.

Theory is that male OBs have such a disadvantage (breeding or survival) in the wild and female OBs a large advantage, that individuals and groups that inherited female sex with OB and male sex without much chance of being OB have a huge advantage. Funny how aquarists seem to be trying to undo years of evolution by trying to get and breed more male OBs? :wink:

Somewhat hard to understand but implied I think by that abstract link
http://www.sciencemag.org/cgi/content/abstract/1174705

All the best James


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## Kanorin

> What I find interesting is why the OB genes became linked to female sex genes.


Yeah. My guess is that the enhanced camouflaging provided by the blotch pattern is beneficial to females because they can better avoid predation. 
For males, increased camouflaging would make him difficult to spot - both by predators and potential female mates! Maybe that's why male marmalade cats are not so prolific in the wild?



> Funny how aquarists seem to be trying to undo years of evolution by trying to get and breed more male OBs?


 :lol:


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## iwade4fish

Marmalade cats are awesome looking, to me.


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## 24Tropheus

iwade4fish said:


> Marmalade cats are awesome looking, to me.


And to me. WC guys seem to display great colours and great fitness (to our eyes). Though the Lady's do not like breeding with em much. Great challenge for the line breeders amongst us is to produce anything so good reliably without losing other good features of the species/variant. Sadly OB genes and traits seem to be of interest to breeders mainly for what novel species can I breed this trait into.
OB Peacocks OB haps the list is ever growing. No real harm I guess as long as they are not misssold as wild type cichlids but not something I am really into unless it is to reveal how the genes work.

All the best James


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