Genetics: Part 2

Colour prediction

Ok, now to colour prediction at last. There are two ways to do this. The first is to look at a cat’s pattern and work through it until you reduce the genes to the dominant red or black (remember, every pattern is made from these colours). This is called de-construction. The second way is to take the cat and begin with black or red, adding the modifier genes until you come up with the existing pattern. This is often what we breeders have to do to work out the possibilities for colour and pattern from specific matings. I will give you examples of each and talk you through how to do them. I’ll start with de-construction, as it’s probably a bit easier. I’ll concentrate on tabbies, colourpoints and bicolours as these are easier to get to grips with.

Deconstruction

• 1. A blue tabby. First of all, remove the tabby gene. This leaves you with a blue cat. Then remove the dilute to leave black.




• 2. A cream and white bicolour. Remove the bicolour to leave a cream, then remove the dilute to leave red.




• 3. A blue tortie colourpoint. Remove the colourpoint to leave a blue-cream tortie. Remove the dilute to leave tortie.




• 4. A white. Remove white to get… Anything is possible. Remember, white masks any colour or pattern combination.




• 5. A lilac tabby colourpoint. Remove the tabby to leave a lilac colourpoint. Remove the colourpoint to leave a lilac. Remove the chocolate to get blue. Remove blue to get black.

Construction

• 1. A cream tabby. Add dilute to red to get cream. Add tabby to cream to get cream tabby.




• 2. A blue and white bicolour. Begin with black. Add dilute to get blue, then bicolour to get a blue and white bicolour.




• 3. A blue-cream tabby colourpoint. Begin with tortie, red and black. Add dilute to get blue-cream. Add tabby to get a blue-cream tabby. Add colourpoint to get a blue-cream tabby point (also called a blue tortie tabby point).




• 4. White. Start with black or red, and add anything you like. As long as you finish with adding white, the cat will appear white, no matter its genetic colouring or patterning.




• 5. A red chocolate colourpoint. (Remember, chocolate only modifies the black gene. This cat would actually be seen as a red colourpoint). Start with red. Add chocolate to get red chocolate (this will appear to the eye as still a red cat). Then add colourpoint to get a red choc colourpoint. Note: The cats would be classed by registering bodies as red colourpoints despite carrying two copies of the chocolate gene.

Notice that in the last examples, I have avoided black colourpoints. This is because, when a cat is pointed, the black gene is called by a different name. It is called a seal. It is the same gene and behaves the same way, but is just known as a different name.

The challenge

As a breeder or owner of a pregnant cat, you will need to be able to generate colour/pattern possibilities based on the pattern and colour of the mother and father. To this end, I am going to leave you with the colours and patterns involved in Tia’s mating. I’d love to see if you can come up with the colours of kittens she might produce. Do remember though that torties or blue-creams are usually only female. Also remember that a tortie mother can pass on either black or red to her offspring, while the father can only pass on one colour.





Tia is a seal tortie colourpoint carrying dilute and chocolate. Remember, seal means black. So in simple terms, she is a tortie colourpoint carrying dilute and chocolate. The father is a cream colourpoint who does not carry chocolate. So, what colour kittens will she produce? For the really enterprising among you, I’d like to know whether they will carry chocolate/dilute as well. I’ll tell you the answer in tomorrow’s post. For those of you that read regularly, you may already have seen it!





To help you, I will outline the mating combinations of Tia’s parents.

Mother: blue tortie tabby carrying colourpoint.

Father: chocolate colourpoint.





De-construction:

Mother: remove tabby to leave blue tortie, and dilute to leave tortie.

Father: Remove colourpoint to leave chocolate, and chocolate to leave black.





Combinations:

All kittens will carry dilute, as the mother has two copies and the dad has none.

Therefore, blues, creams or blue-creams are not an option, because no kitten will get two copies of the dilute gene.

All kittens will carry colourpoint as the dad has two copies. Colourpoint kittens are a possibility if the mother passes on her single copy to offspring.

If the mother carries two tabby genes, all offspring will be tabby. I know Tia’s mother did not, which means tabby is a possibility as she only carries one copy of this dominant gene.





Girl kittens: black, black tabby, seal colourpoint, seal tabby colourpoint, tortie, tortie tabby, seal tortie colourpoint, seal tortie tabby colourpoint.





Boys: black, black tabby, seal colourpoint, seal tabby colourpoint, red, red tabby, red colourpoint, red tabby colourpoint.





Note that boys are not torties, and that boys can be solid red where girls cannot. This is because the father always passes a black gene. Girls, because of their x chromosomes can express both black and red at the same time, but for the boys, it is the mother who has the final say on colour, hence the ability for her red to be expressed. This is because it is the mother who passes on the X chromosome and the father the Y. Remember that the colour genes are on the leg of the chromosome missing from the y.





I hope this has been helpful, and sorry it’s been so long and confusing!

Genetics: Part 1

The human here. As Tia mentioned yesterday, all this week, I’ve been allowed to post on her blog to address some things that I hope will help others if they ever find themselves in a position where they have a mum cat to look out for. I really hope this week’s posts help even one person.






So, your cat is pregnant. One of the most common questions people ask is what colour the kittens will be. This all comes down to genetics, and they are complex enough that I’m going to split them into two posts. I’ll start with the basics today.

What is a gene?

In its simplest form, a gene is a part of your DNA. It is a chain of different molecules which code for the production of a protein in the body. These proteins and coding strands are responsible for many things from hair colour to height, skin tone and even weight to some extent (no, that can’t be used as a valid reason to go eat chocolate!). In short, genes are the things that make you look the way you do, and often, have the health problems that you experience. They are passed to you from your mother and your father. In this post, I’ll be looking at genes specifically linked to coat colour and pattern, as these are the best understood so far in the cat world.

How do we get genes?

At the point of fertilization, a sperm from the father and an egg from the mother join. Each of these cells carries genetic, DNA information which binds together when the cells join. DNA, and therefore genes, are housed on things called chromosomes. Most are x-shaped, one half being formed from the mother’s DNA and the other from the father’s. Genes therefore have a pair partner on the opposite strand of the chromosome. However, whereas a female possesses all X shaped chromosomes, a male has one in each cell that is a Y shape. It is missing a leg. This means that genes on the opposite corresponding leg have no pair partner. Cat coat colour genes exist on this chromosome, which explains why girls only are torties. Boys can only express one colour at a time due to not having a pair partner in the DNA for the colour gene. Those male torties that do exist are sterile. This is because they not only have an x-y chromosome as normal males do, but they have an XXY set-up, meaning they have an extra, unwanted chromosome. This has the added effect of making them sterile.

Dominant and Recessive/dilute

Genes come in two types. These are called dominant and recessive. Dominant genes do what their name suggests; they dominate. Just one dominant gene will mean that a cat exhibits the trait linked to that gene. Recessives cannot manifest alone. There needs to be two recessives in order for the physical trait to be noticed. To understand genes, you need to remember that they always come in pairs, one from the mother and one from the father. When it comes to coat colour, the recessive gene commonly seen is called a dilute gene. This is because it dilutes the true colour of the coat to form something else.





A person can be said to be a carrier of a recessive, but not a dominant. Why? Because carriers possess the gene, but do not show the physical trait. Remember, if a person, or a cat, has a dominant gene, they will show that trait even if they only have one dominant. So, if they have a dominant, they cannot carry the gene because they show the trait. The same is true if they possess two recessives. However, if they have only one recessive, then they will possess the gene but not the trait, so can be called a carrier. This will be important when we come on to predicting colour possibilities in cats.





Speaking of cats, let’s get to colour. Believe it or not, there are only two true colours in cats. Despite the profusion of different coloured coats and combinations out there, they all come from only two colours. Those are black and red. Every coat colour’s genetics can be traced back to either black or red. But how? That’s what I’m going to try and explain. And that’s when it gets complicated.





Dilutes, the recessives remember, are very important in coat colour in cats, as they allow deviation from the blacks and reds. Black and red are dominant, but the dilutes, even though they are recessive, are able to work in tandem with this dominant to alter it. If a cat has the dominant gene for black, but also possesses two dilute genes, then instead of black, their coat will turn blue. Likewise, if another cat has the dominant for red, two dilutes will work with the red gene to produce a cream coat.





But you’ve seen cats that show black and red together, haven’t you? Or cats who show blue and cream? Well, that’s very common. These cats are called torties and blue torties/blue-creams. Most of them are female, but a very small percentage can be male. However, because colour genes are sex linked, any tortie male is sterile and can never reproduce. Females exhibit black and red or the dilute forms of them due to having two x chromosomes. So although the two are dominant, they can both exist in harmony given their position on chromosomes. If a boy had two x chromosomes, he could do the same thing.





So, by the logic we’ve already explored, you couldn’t have a cat with red and cream in its coat. Why? Because it takes two dilute genes to make cream, and if you have two dilutes, they cancel out the red. Similarly, you couldn’t have a cat with black and blue. The same is true when you look at red and blue or cream and black. I hope you understand why. Remember, two recessives/dilutes code for cream and blue, so when they’re there, they cancel out the red and black. Blue-cream exists together because both are dilute colours. Red and black exist together because both are dominant colours.

Chocolate

Just to complicate things further, there’s another way that colours can vary. Well, there’s more than one, but let’s keep it simple. Chocolate is rare, and is an alteration of the black dominant gene.





Ok, I lied when I said we’d keep it simple, because chocolate isn’t. It’s the interaction between a dominant and a recessive which can also be altered by a dilute. Confused? I was for a long time. Basically, chocolate is a recessive gene. That means, as with the dilute, that two copies of chocolate must exist before the cat can have a chocolate colour visible on its coat. One copy alone makes the cat a chocolate carrier. However, here’s where things get extra tricky. Chocolate, although it is a recessive which will modify only the black dominant gene, can itself be modified by that old friend, the dilute. If a cat has two copies of chocolate and two dilutes, then it makes lilac. Obviously, if a cat only has one dilute then chocolate still wins. If it has only one chocolate, then the dilute will act on the dominant coat colour, red or black.





Ready for more complication? Chocolate cannot impact or modify the red gene, so if you have a red boy or girl, they can have two copies of the chocolate gene and not show it. They can also have two copies of the dilute and still not show chocolate or lilac, although in this case, the base colour of the coat would be cream, not red (remember, red plus two dilutes =cream).

White

Although this isn’t exactly a colour, it is almost like a trump card, for if copies of a white gene exist, they mask all other colours. So even if a cat possesses the genetic make-up to be a tortie, it will still appear white due to the masking properties of this gene. Even if only one copy exists, the cat will still be white. This is the ace of spades when it comes to colours!

So, to recap

Black and red are dominant, so only one copy is necessary to see a physical trait presented.

Dilute is recessive. If only one copy exists, a cat is a dilute carrier. If two copies exist, black cats become blues, red cats become creams, and tortie cats become blue-creams.

Chocolate is a recessive gene which only modifies the black dominant. Any reds with two copies of the chocolate gene will remain red but are called red chocolates. Two copies of the gene on a black cat will make it a chocolate. One copy will make any cat a chocolate carrier.

The dilute modifies chocolate, if two copies exist, to become lilac.

White is the trump gene, masking all other colours. Any cat with even one copy of the white gene will appear as all white. Any cat with two copies of the gene will consistently produce offspring who are all white.





Ok, now that we have that sorted, we do, don’t we? It’s time to move on to patterns.

Patterns

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• Colourpoint is a recessive gene, so two copies are necessary for a cat to be pointed.




• Tabby is a dominant, so only one copy is necessary for tabby to become the pattern.




• Bicolour is also dominant. When one copy of the gene is present, a black cat becomes a black and white bicolour, a red cat a red and white bicolour, and a tortie a calico. Remember that with the influence of the dilute, you can also get blue and white bicolours and cream and white. If a cat has two copies of the gene, it will be mostly white and will be called a van.




• Shaded/smoke/shell: This too is dominant. One copy alone makes a black cat a black smoke, a red cat a red smoke and a tortie a tortie smoke. The smoke gene varies in its expression though, producing something called variable penetrance. This basically deals with the length of the hair shaft that the colour extends to. Smokes have a hair shaft that is mostly coloured, but with a white undercoat. When the colour extends 50% down the shaft, the cat is a shaded rather than a smoke. Some cats have colour just on the tips of the shaft, and these are called shells.




• There is one final pattern, silver/golden, but it is quite a complex one to explain given that it is a combination of three genes working together. If any of you wish to know more, please write me privately and I’ll direct you to an informative article to read.

Sleepy Sunday

Friends, as my pregnancy progresses, I find myself wanting to sleep more and more. The only problem is that I can't! Why? Cuz my babies have been injected with wiggly worms that make them keep moving all the time. One baby has gotten itself into a real comfy position next to my ribs, and when it kicks, it plays football with the bottom one. This is guaranteed to make me get up from a comfy position and roll around or walk a little to try and ease the discomfort and settle the baby so that I can go back to sleeping. I'm spending a lot of time on my back now. I find that this alters the position of the wrigglers inside me and gives me a few moments of kick free peace. It doesn't last long though. All those babies weigh a lot, and that weight presses on my organs when I'm that way up. That isn't too comfy either, so I have to keep rolling.






I'd gone off my food a little in the last few days too. This isn't uncommon for a mummycat with a yummy tummy stuffed full of babies. There simply isn't room in there for a big meal. however, the human knows that everything I eat is going to my babies. Even though I have a belly the size of a small whale, she can still easily feel my backbone and pelvis, so she knows it's very important for me to keep eating. She got out the really special treats, the ones I'd do anything for, and she's been crumbling them on the top of my stinky goodness. They're freeze-dried chicken and they crumble to powder which makes the food smell and taste so good that I can't ignore it. Those babies just have to move over and make room, cuz it's not staying in the bowl! So much for not eating...





My safe place has now been augmented by an upside down cardboard box with a hole cut in the front for me to go in and out. It's great in there, very dark and private and cosy. She's set one up in the bedroom for me too after she caught me trying to nest under the bed, but I haven't bothered with that one yet. I prefer to spend most of my time hanging out on the towel she's put on top of the kittening pen. It's comfy up there, and I can watch the world go by whilst guarding my safe place. She says she'd rather I nested, but she's not worried. On the pen or in it. Either's good enough for her until babies come along.





My belly gets bigger by the day, and even the human can easily feel baby movement now. The little footballer even managed to kick her in the stomach the other day when we were cuddling. She found this highly amusing. My ribs did not.





There's almost only seven days to go now, and I fear I may have passed my last peaceful weekend for a long, long time to come. The human's having silly nightmares about the litter, that something will go wrong when I'm delivering. I'm not worried though. What will be will be. Dogman came this week and took some pictures of the yummy tummy, so as soon as he emails them to the human, I'll get her to put them up here.





For the rest of this week, I've asked her to put up some educational posts. We're going to look at genetics, how to prepare for the arrival of kittens, how to help your cat during birthing, and how to care for mum and babies once they have been born. The genetics alone is massive, so will probably take up two posts, but we hope it will be helpful for some peoples who find themselves with a pregnant cat. I'll pop in from time to time to give you updates if anything happens, but this last week is likely to be long and tedious and very uncomfortable. Thank cod it's not stupidly hot here too, that's all I can say!





I have to go to see our nice vet people tomorrow. She's going to cut my nails and probably have a feel of the yummy tummy, as she's excited too about babycats. She'll then show my human how to take my temperature, and that I'm not looking forward to. It's important to take in the last week though. When birth is close, it will drop within 12 hours. The human's breeder friend is coming down to help us if we need it, so that gives the human an indication of when to call her to come. It's a loss of dignity for me though, and i intend to put up a tremendous fight whenever I see that thermometer thingy coming! She may be able to placate me with lotsa treats though... Who says I'm not shallow!





Anyway, friends, I hope you enjoy the week of education. Think of me as I grow fatter, eh? Soon, very soon, there'll be lots of little me's running around. I can't wait!

Mommacat Monday

Wow, friends, it's my second mommacat Monday already! Isn't time flying! The human says she wishes it would, so she obviously doesn't feel the same way. Since last we spoke, we've had an eventful few days!






It all started yesterday with a trip to the litterbox. Nothing abnormal about that, I hear you say, but the litterbox is the one not agreeing this time! Friends, to put it very politely, I was in a bad way, and came out of there leaving a stinking liquid mess behind me and with my poor lady bum covered in the stuff! The human found me, or rather, the mess found her when I jumped up on her. I thought if I pretended like nothing had happened, the mess would just go away. I know from experience that I can't clean that off, but was too embarrassed to ask the human for help. Do you know how that makes a girl feel? Very very small, that's how.





As soon as the human found me, she whipped me off to the bathroom to clean me up, but once there, she realised that the baby wipes (they should be marketted as cat bum wipes, cuz they're real good at this!) were in the other room. In the time it took her to get them and come back, something else had happened. A small amount of sticky liquid had dribbled out of me and made my fur very wet. the human went into uber panic. She thought it might have been blood, and if it was, it would mean that I was reabsorbing my babies for some reason. She still doesn't know whether it was or not, but she kept a very close eye, or should I say hand, on me all night long, and I didn't do the same trick twice. It may have just been a bit of left over litterbox stink that I couldn't hold onto when she started to clean, but neither of us are all that sure.





That first clean up was to be one of many, well, four to be precise, but each one was very liquid and incredibly stinky. It smelled just like it did last year when I got real, real sick, so the human spent a sleepless night worrying about me, and cleaning my litterbox before my feet had even touched the floor on the way out! She says you don't leave that stuff hanging around.





Well, all that sickness last year must have taught her something, cuz her clean up of me and the box was so good that this morning was my last bad episode and I haven't shown signs of having another. Two hours after my last one, I threw up a big hairball, so she's wondering if that had something to do with it, although I've never had the runs before when trying to get rid of one of these. The simple fact is that we don't know what caused it. She dosed me with a pro-biotic that breeders like her give to kittens who have the squits (she says that's what you call it when you have runny bum syndrome). She says it's really good not only for clearing squitty bums, but stopping them as well. It's called Fortiflora for anyone else who may need it and it's made by Purina.





I've been tired all day and very quiet. It takes it out of a girl to produce that much poop! The human thought my tummy had changed shape this morning and was convinced that I must have lost a baby or two, but when I did finally start to eat again, I plumped right out. She says she's gonna try and find her stethoscope as she should be able to hear baby heartbeats about now, but she doesn't know where the stethoscope is, so her and Mark are gonna have to hunt for it.





She's been busy ordering stuff for my babies all day. She says she'll make a list of all the things in her kittening kit on a post so that you all can see what kinds of things you need to have at hand. That will fill a post while she's away in cold, cold Alaska. She says she may even do the genetics post then too so that you can all have fun with trying to puzzle out what colour babies I might have! Oh, how about this for an idea? The human and i are thinking of running a competition but we're not sure what everyone else thinks. We'd like you all to guess how many babies I will have. I know the vet peoples said three, but as I told you, that doesn't really mean much at this stage. It would also be fun for peoples to guess how many baby boys and how many girls there would be. To make it really, really interesting, we could get you to guess colours too which would mean you'd have to read and learn about genetics! But this might be too involved for most peoples. What do you all think? Would you enter if you had to guess litter size and sexes? Would you still enter if you had to guess colours as well?





We gotta think about prizes too, and something kitten related to tie in with the competition. Any ideas?





Well, that's it for today as the human says she has to go out for a little while. See? no sooner am I better than she's abandoning me! Heartless human!