It is currently Tue Oct 24, 2017 12:28 pm

All times are UTC [ DST ]




Post new topic Reply to topic  [ 69 posts ]  Go to page 1, 2, 3, 4, 5  Next
Author Message
 Post subject: Genetics of the Bengal
PostPosted: Mon Jun 29, 2009 4:03 pm 
Offline
Asian Leopard Cat

Joined: Fri Aug 24, 2007 3:43 pm
Posts: 2445
Location: France (Dijon)
Perhaps someone could make this a sticky... ;)

Just a quick explanation, some other sites will be better for details !

Colours in cats and in Bengals may seem a bit hard to understand at first but it's not so hard once you've understood a few principles ;).

Colours are genetically determined.
As every living being (well, eucaryotes at least :lol: ) cats have two sets of chromosomes.
Each gene is carried on what is called a locus (plural loci), which is the "place" it takes on the chromosome.
For one gene, there are very often different possibilities (caused by a variation in the DNA pattern) which are called alleles.
Because you have 2 sets of chromosomes, you have 2 alleles for each gene.
They can be similar (homozygous) or not (heterozygous).

Some allele may be dominant (they will take over any other allele) or recessive (you will see the result only when your cat is homozygous for that gene).
By convention dominant alleles are written with a capital letter, recessive in er low case (correct me if that's not the right term ;)).

Many genes code for a cat colour, we usually list them in the alphabetical order :lol:... In bold, the ones that interest us most in Bengals ;) (for the accepted colours).

A/a : agouti. Agouti means some hairs are ticked so cats with a pattern (stripes, spots or all ticked over like Abyssinians) are agoutis, AA or Aa.
aa cats are called solid (for eg a black cat is aa). All Bengals (of recognized colours) are A- (usually AA, although some Aa exist, when you cross 2 of them, that's when you get melanistic Bengals... ;))

Image

Agouti (brown) bengal

Image

Solid black (melanistic) bengal

B/b : black is dominant, B. A patterned "black" cat is what we call brown ;) (like brown bengals ; the black shows in the patterns and tail end). b is for chocolate cats (bb) which do not exist in Bengals. All Bengals are black B-, but with some others genes kicking in to get the other colours... ;)

Image

Chocolate oriental cat (this color doesn't exist in Bengals, see above for blacks)

C/cb/cs : the "category" gene. C means no influence of that gene on the colouring, it's the "normal" cats (see first pic for illustration).

cb is the burmese colouring : darker extremities but eye colour normal (green to yellow) and body colour just a bit lighter.
In Bengals, that's the sepia snows or AOC snows, cbcb.

Image

Sepia snow bengal (BRIDLEWOOD KNIGHT WITH WHITE SATIN)

cs is the siamese colouring : dark extremities and creamy body (with pattern showing if cat is A-), blue eyes.
In Bengals, that's lynxpoint snows, cscs

Image

Blue eyed snow bengal

Because cs and cb are co-dominant, if you have both of them you'll have an in between colouring : body a bit darker than colourpoint and aqua eyes. That's the mink colouring, cscb.

Image

Mink snow bengal (Purebliss Pleasuredome)

You also have a c which gives white cats with blue eyes and ca which gives albinos cats but not in Bengals.

D/d is the diluted gene. D- cats are normal but dd cats are diluted.
Here are the dilutions of each colours :
black => blue (ie, blue Bengals are B- dd)

Image

chocolate => lilac
orange or red => cream
... (I'm leaving the fawn, cinnamon and so on to Abyssinian owners :lol: ).

I/i : inhibitor gene. Here, we have the modified gene which is dominant : a "normal" cat will be ii, a cat Ii or II does not synthetize the red/yellow pigment, pheomelamine.
That's what cause silver cats (in patterned cats) or smoked cats (in solid cats).

Image

Black silver bengal

Although we mostly think of black silver cats (like silver Bengals), it can also happen on red cats : they end up quite a strange but beautiful colour ;) (not white because it's not as easy as that...).

L/l : L for short hair, l for long hair. Bengals are L-.

Ta/t : the "ticked" gene.
Ta is not entirely dominant over t and causes the ticked pattern in cats such as Abyssinians, Somalis and so on.
tt cats will express the pattern carried by the mc gene.
Tat cats will have more markings such as collars that TaTa cats.

Image

Ticked abyssinian

Mc/mc : the mackerel and blotched patterns gene. Mc dominant will code for a mackerel pattern (vertical), mc recessive for a blotched pattern (circular).
A theorical allele, mz, is supposed to code for the horizontal pattern found in Bengals and ALC but as spotted should be Mc- and marbled mcmc it's a bit contradictory...


Image

Marbled brown bengal

Sp/sp : it was first thought that spots were another t allele but it seems that it's a different gene that interracts. Sp is dominant and breaks up the pattern into spots. When the cat is mackerel, that means spots, when the cat is blotched, that means big patches like those you can see on some marbles... (probably)

Image

Rosetted brown bengal with horizontal alignment of the rosettes

I put those 2 last genes not in the alphabetical order, because I thought it would be a bit more understandable to talk about the T gene first ;).

There are of course lots of other genes (S for white patches, sex linked O for the orange coloured cats...) but those don't apply to Bengals and so I won't talk about them here, I think there's already enough to understand... ;)

Here are a few exemples of Bengal colours written in genetic code (considering they're all A- B- L- mzmz ) :

Brown spotted : C- D- ii Sp- T
Brown marbled : C- D- ii tbtb
Blue spotted : C- dd ii Sp- T
Black silver marbled : C- D- I- tbtb
Lynxpoint snow spotted : cscs D- ii Sp- T-
Black silver sepia snow marbled : cbcb D- I- tbtb

And so on... ;)

That's why sometime breeders get some colours they have some difficulties to determine, because silver snows are not VERY different from snows to the untrained eye, the same is true for silver blue... Also, you can have some dark sepias and light browns...

That's why understanding the genetics is important because usually you can work up the colour from the parents and grand parents ;)...

Edited to add pics.

_________________
AnnC, Onyx and Chaos
Image
http://onyx-et-chaos.over-blog.com/
Image


Last edited by AnnC on Sat Mar 19, 2011 7:37 pm, edited 4 times in total.

Top
 Profile  
 
 Post subject:
PostPosted: Mon Jun 29, 2009 4:08 pm 
Offline
The Boss
User avatar

Joined: Thu Jul 01, 2004 1:41 am
Posts: 1240
Done...

Thank you for taking the time to write this Ann, very much appreciated! :wink:


Top
 Profile  
 
 Post subject:
PostPosted: Mon Jun 29, 2009 4:20 pm 
Offline
Asian Leopard Cat
User avatar

Joined: Sun Feb 08, 2009 2:52 am
Posts: 3090
Location: Essex, UK
Thanks for this! Am reading it now! :D

_________________
Image


Top
 Profile  
 
 Post subject:
PostPosted: Mon Jun 29, 2009 4:27 pm 
Offline
Asian Leopard Cat

Joined: Wed May 13, 2009 1:09 pm
Posts: 1694
Location: Derbyshire
Thank you so much Ann, I am going to print this and learn as much as poss. xx


Diane & The Posse


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jun 30, 2009 1:05 am 
Offline
Asian Leopard Cat

Joined: Wed Sep 12, 2007 1:55 pm
Posts: 8421
Location: south east england
good work AnnC, thanks :D


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jun 30, 2009 10:08 am 
Offline
Asian Leopard Cat

Joined: Fri Aug 24, 2007 3:43 pm
Posts: 2445
Location: France (Dijon)
You're welcome ! ;)

_________________
AnnC, Onyx and Chaos
Image
http://onyx-et-chaos.over-blog.com/
Image


Top
 Profile  
 
 Post subject:
PostPosted: Wed Jul 01, 2009 9:06 am 
Offline
Asian Leopard Cat

Joined: Tue Jan 16, 2007 2:47 pm
Posts: 3809
Location: UK
AnnC wrote:
Ta/T/tb : the pattern gene. Every cat, even if solid, has a pattern determined in his genes (which explains the "phantom patterning" seen on some black cats in a certain light : that's because not all black hairs are the same, some are really solid, others have bands of "different" black colours...).
Ta is dominant and codes for a all ticked, non tabby cat like Abyssinians.
T is for the mackerel pattern and is recessive to Ta but dominant to tb.
tb is for the blotched or classic pattern.
Bengals are T- (mackerel but with another gene which makes them spotted...) or tbtb (marbled).
All tabby cats have spots underbelly too (that's NOT specific to Bengals, although Bengals must have them...) except if there's a white patch over it


A correction to the above:
The Ta/T/tb nomenclature is no longer used, as the forms ta, T and tb are not allelic.
Hence Mc to represent the dominant Mackerel pattern, mc to represent the recessive classic pattern and T to represent the Ticked tabby pattern with t being non ticked tabby pattern.

_________________
Elaine


Top
 Profile  
 
 Post subject:
PostPosted: Fri Jul 03, 2009 3:06 pm 
Offline
Asian Leopard Cat

Joined: Fri Aug 24, 2007 3:43 pm
Posts: 2445
Location: France (Dijon)
You're right, sorry, I learned that with the ancient nomenclature and still didn't update :lol:

I'm editing the first post ;)

_________________
AnnC, Onyx and Chaos
Image
http://onyx-et-chaos.over-blog.com/
Image


Top
 Profile  
 
 Post subject:
PostPosted: Sat Jul 25, 2009 2:23 pm 
Offline
Asian Leopard Cat

Joined: Sun Jul 01, 2007 4:15 am
Posts: 1290
Location: USA
Just found this and wanted to add that the gene for silver coat color has been mapped in the cat genome and it's different from all the other coat color genes:
http://jhered.oxfordjournals.org/cgi/co ... suppl_1/S8

They haven't confirmed the actual gene yet by sequence/cloning, but the most promising candidate seems to be gene SLC18A2, which is related to the gene that is mutated in Europeans with pale skin. I guess if this is confirmed, white people are genetically speaking the equivalent of feline silvers? Isn't genomics fun? :lol:

_________________
Image - Don't forget Bengal Rescue!


Top
 Profile  
 
 Post subject:
PostPosted: Sat Jul 25, 2009 9:29 pm 
Offline
Asian Leopard Cat

Joined: Wed Sep 12, 2007 1:55 pm
Posts: 8421
Location: south east england
oo that's interesting tameeria, thanks! :D


Top
 Profile  
 
 Post subject:
PostPosted: Fri Sep 25, 2009 11:53 pm 
Offline
Asian Leopard Cat

Joined: Mon Jan 12, 2009 10:49 pm
Posts: 584
Location: Oxford, UK
Where can I read more about feline genetics? Where is this research carried out? I work in the field of genetic analysis, but haven't come across anyone working with cats...


Top
 Profile  
 
 Post subject:
PostPosted: Sat Sep 26, 2009 11:42 am 
Offline
Asian Leopard Cat

Joined: Fri Aug 24, 2007 3:43 pm
Posts: 2445
Location: France (Dijon)
You could have a look on pubmed if you're familiar with the more difficult terms ;)

Apparently some researches are done at some vet schools, my genetic teacher do some researches...

I know a good site explaining the more technical aspects (as the pigment repartition and so on) but it's in french... (for those who happen to understand french : http://www.ailuropus-mainecoon.com/gene ... leurs.html )

_________________
AnnC, Onyx and Chaos
Image
http://onyx-et-chaos.over-blog.com/
Image


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 28, 2009 3:20 pm 
Offline
Bengal Cat

Joined: Wed Dec 12, 2007 11:45 pm
Posts: 38
Location: canada
very usefull post Ann :-)

The problem with pubmed is that you have to pay to see almost all the papers, often google will give you more informations

here is a link for new paper (2009 oct 26) that will interest the ones that have a scientific background:
Defining and Mapping Mammalian Coat Pattern Genes: Multiple Genomic Regions Implicated in Domestic Cat Stripes and Spots.
http://www.ncbi.nlm.nih.gov/pubmed/1985 ... dinalpos=1

_________________
Image
www.astartebengals.com


Top
 Profile  
 
 Post subject:
PostPosted: Tue Nov 24, 2009 4:48 pm 
Offline
Asian Leopard Cat

Joined: Mon Jan 12, 2009 10:49 pm
Posts: 584
Location: Oxford, UK
Astarte wrote:
very usefull post Ann :-)

The problem with pubmed is that you have to pay to see almost all the papers, often google will give you more informations

here is a link for new paper (2009 oct 26) that will interest the ones that have a scientific background:
Defining and Mapping Mammalian Coat Pattern Genes: Multiple Genomic Regions Implicated in Domestic Cat Stripes and Spots.
http://www.ncbi.nlm.nih.gov/pubmed/1985 ... dinalpos=1


This looks like a very interesting paper Astarte. I just read the abstract which sheds a little light. I cannot read the entire paper though. I daren't try and do so through work, as there is no way I could claim this is work related. Do you have a copy you could email to me? I'm really not prepared to pay for it as I'm not a breeder - just curious...

I am now particularly interested in the interaction between the Ticking (T) gene and its various alleles and the Agouti gene (A). There doesn't seem to be much information on this in the thread or in the abstract.

I'm suspecting heterzygous Aa cats have better black expression, and are being introduced from silver lines using heterzygous Aa American Shorthairs I suspect. Hence many cool browns coming from silver x brown breedings with good black expression are also producing melanistics.

I'm particularly interested as to why some cats show banding in the hairs of their dark markings (spots & marbling) whereas others show no banding and are jet black down to the skin, yet show banding elsewhere - I wonder what the genetic basis of this would be, is it linked to the heterozygosity of Aa perhaps?

However, I also suspect it is more complicated than this as for such a simple explanation to be the case ALCs with good black expression would also have to be heterozygous Aa, and hence 25% of ALCs would be melanistic. There must be a key intereaction between these genes which I'd really like to get my head around.

_________________
with best wishes

Tim and the Family Feline

Tigra, Azlan, Bilbo and Zion


Top
 Profile  
 
 Post subject:
PostPosted: Tue Nov 24, 2009 6:21 pm 
Offline
Asian Leopard Cat

Joined: Tue Jan 16, 2007 2:47 pm
Posts: 3809
Location: UK
My feelings are that silver cats in other breeds have been bred for generations to rid themselves of tarnishing. By silver to silver matings ad infinitum and with each mating removing the tarnished individuals and by selecting only the best Silvers to breed with, the clear silver cats emerge.

By getting rid of the rufoused cat "underneath" the inhibitor gene, and replacing it with selected cooler cats, the tarnish doesn't appear so obvious.
I would think that over the years that silver producers have selected cats with good black/white contrast too so the black expression in these cats is predominant.
That has probably been achieved through many, many generations and has involved I would think a legion of polygenes, some of which I would think are of dominant inheritance.

Mating the Silver ASH with its abundance of these polygenes to the Bengal, brings out these characteristics, so Bengal cats from Silver matings who have not inherited the Silver gene itself do tend to be cooler and with darker markings, or have good contrast, due to the influence of these polygenes.

That is my theory anyway. :)

Where Aa comes into it I am uncertain, I know that the pattern type/colouration that is the Charcoal Bengal has been found to be Aa, whether that is causative or part of a larger genetic complex to produce these cats I am unsure.

(BTW apart from a very few Silver individuals, most Bengals with Silver in the lines descend from only the one ASH, that is a cat called SCHOONERS SALT WATER CLASSIC)

_________________
Elaine


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 69 posts ]  Go to page 1, 2, 3, 4, 5  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
Powered by meemonkey