Released: 13/02/2015. Updated: 29/04/2015. Translated: 29/04/2015.
X and Y chromosomes and inheritance of color in cats
Cats have a pair of chromosomes, like all mammals, X and Y chromosomes are structures that carry genetic information that defines each individual, and also inherit their children. Females have two X chromosomes (XX) and males have one X and one Y (XY).
Within each chromosome are genesthat are the hereditary units each. These always occupy the same place, either in the X or Y chromosome, and this own place is called locus. And each gene has two alleles, one on each chromosome, locus containing the same information about the same character.
The Y chromosome appears when determines that the cat is male (XY), but cats that have both chromosomes as X are female (XX). On the Y chromosome seems to be missing one of the blades of the X, so it lacks some genes that do have the X chromosome, which is why there are genes that their inheritance is sex-linked, that depending on whether female is (XX) or male (XY) will have two genes for that character, or just one.
The color is a sex-linked hereditary, which means that only appears on the X chromosome (For more information with pictures and all possible combinations.
Cats can only have two colors or pigments, black (eumelanin) or red (phaeomelanin). The allele for black gene is "o" and the allele for red gene is "O". As we said before, the color is located only on the X chromosome, so it may be that females have a chromosome, black allele, and the other red allele (Oo) to take his mantle both colors, while males, can only contain a color, as the allele is in X, red, or black chromosome. Depending on the nomenclature used, the black color can also be named as "B". In this case, the lowercase b is used for the recessive allele Color Chocolate, flattening the cells of hair color black cat, and by reflecting light, it is a chocolate brown. For this reason, we decided to use the nomenclature of the red "O" and "o" for black and not go into possible misunderstandings.
X chromosome inactivation in females (all mammals)
The females, as we have said, have two X chromosomes When a gene different color on each X chromosome, the cat is two colors (sometimes 3 when the cat also has the S gene, which is responsible for White Spot, but this has nothing to do with the sex chromosomes), and this is caused by what is known as "inactivation of the X chromosome," Almost all female mammals are mosaics that is, have a mixture of Two different genetic cells, although this may not be visible to the naked eye. This suggests that having two X chromosomes could be some some genetic (too many genes for a single character) anomaly, but females exceed that problem by inactivating one of the X chromosomes in the early development of female embryos, each cell inactivates one of her X chromosomes randomly. Each of these cells over time results in a patch of cells in adult female has the same inactivated X chromosome.
The random inactivation means that a female mammal is a mixture of two different cell types. Parts of your body using X inherited from his mother, the rest uses the X inherited from his father. She is a mosaic of two different cell populations. In cats it is visible as the tortie females; some X chromosomes lead red coat, while others lead black coat. This is called genetic mosaicism.
Tricolor male cats (Tortie males)
For all this, we can think that only females have two colors (three if you have the S gene). This is not so, since cases of tricolor male cats or "male torties" known. A great deal of controversy over this type of male cats, has written much about them, and have come to try to miracles, cats with a high value of genetic aberrations have been hidden and "disappeared" and even They have even suggested that it was better put them lethal injections before coming to light (see here) ... and the truth is that it is necessary to better define and explain what this phenomenon is due in male cats, to avoid the future confusions and closed or persecutory attitudes to these males. Sometimes it has come to want to impose the systematic castration of these individuals under the assumption that it is genetic aberrations that must be eliminidas breeding programs, nothing more.
Originally, it was believed that all males tortie cats were individuals whose chromosomes were XXY (Klinefelter syndrome), which meant they were infertile.
Thanks to new and less costly genetic testing that we have at our disposal, we can know better this phenomenon can best recognize these males and what occurs in each his mantle to look like the female torties. For example, Sarah Hartwell explains a case; a breeder was investigating its fertile tortie male with white. This cat tortie transmitting only red gene and never the black color to your offspring. The tissue samples will be taken this stallion showed that their cat was a genetically red and white cat, and XY chromosomes were normal; in their X chromosome allele OR had to red. Black areas of the mantle were due to local mutations of skin cells - as moles or birthmarks - and he was genetically a red and white bicolor. Since then there have been more studies on tortie males, many of them were fertile. This has helped to dispel the notion that most of tortie males are infertile product of chromosomal abnormalities. In fact, there pedigrees with two or three generations of fertile tortie male.
These are not the only cases which may present a tortie male. The cases are many, let us turn to define them one by one.
- Genetic anomaly.- A normal sperm carrying a Y chromosome, either X or Y. A normal egg has only one chromosome, the X. These unite at fertilization to form either a female individual with XX chromosomes or male individual with XY chromosomes. Sometimes egg is abnormal and contains more chromosomes that would correspond XX, and even lack of chromosomes 0 (Turner syndrome). When an egg that is fertilized by a normal sperm, becomes XXY Klinefelter syndrome), XXX or XO (Turner syndrome) (Will not develop because he will die in fetal stage). It could also be fertilized by a sperm abnormal. An abnormal sperm would be XX, XY, or 0Y, or 0 (0 means no X or Y). If one of these sperm fertilizes a normal egg and can produce XXY (Klinefelter syndrome), XYY, XXX or XO Turner syndrome). If abnormal egg that produce XXXX, XXXY, fertilized etc. In humans mental retardation often appears when there are 4, 5 or 6 X chromosomes present. It is not known how often these abnormalities can occur in cats, as these have been studied in other mammals. This type of anomaly, or genetic aberration, produce infertile animals. It do not need to be castrated and that they will not be able to reproduce, but usually have sexual behaviors, if male, marking, aggression, fights, escapes, and in females heat and recommend their castration for these reasons, otherwise unless that show mental retardation, or the presence of disease genes in chromosomes repeated, often have no more problems.
- Somatic mutation in the skin.- A male chromosomally normal, ie XY, and the red gene O on the X chromosome, has a somatic mutation in some skin cells - as if they were moles or birthmarks - changing the color of the skin and they give the black tone (or blue if diluted, or any of the colors that are affected by the gene b or bl ). As explained in somatic mutation, this feature is not inherited, it means no kittens will inherit the two colors, only the red that is the cromosoma X. These cats can be studs normally, although studies somatic mutations associated with the likelihood of diseases such as cancer. Let us not forget that human beings have this type of mutations, such as moles, and we all develop melanoma, doctors also don't recommend us to stop reproducing by this.
- Chimeras.- a chimera is an individual who has in itself cells of two individuals (or more) different. This occurs in the uterus, when two or more zygotes merge into one after fertilization within 3 weeks. That makes different parts of the same animal body corresponding to different individuals having different DNA in their cells. That is, two or more individuals in one. If embryos are merging different color, one black (and variones) and one red (and its variations), we have an individual in two different colors, and if it happens that both individuals were male, we have a male, having cells of two different males, and has a red and black parts. These males are fertile and have no problems with the fact that chimeras may be studs normally. The color that will give their offspring depends on which of the two individuals has formed the testicles (which is where sperm develop), or even two, if there is a testicle that belongs to each individual, and each different color. Needless to say, in this case it is not necessary to castrate at all, as it will not cause any problems in their offspring. The children will not acquire the status of genetically chimerism receive the genes of the individual, or individuals, who produce sperm, can be completely healthy children.
- Masculinized females.- this case is due to a congenital problem, that is, something that happens in pregnancy and is present at birth. When a cat is genetically female (XX chromosomes) during fetal development and a hormonal imbalance in which increased levels of male hormones happens, the appearance of male genitalia develops, but inside are the gonads (ovaries) female and can even develop penis. If the female is turtle, it will seem a male turtle, but actually is a masculinized female. will female behavior, and it can not reproduce, so in this case if castration is recommended. Sometimes in the scrotal sacs they are not the ovaries, but in them fat bags.
- Hermafrodites.- the hermafodites individuals are organisms possessing both reproductive organs usually associated with the two sexes, male and female. That is, those living beings that have a mixed system capable of producing male and female gametes, although several states hermofoditismo (see here ) or be pseudo-hermafodites. It can happen to be a tortie cat with both sexual organs of both female and male, or only male and female have internally. They can be fertile or not. These cases should be consulted with veterinarians.
After analyzing all possible cases of tortie males, we would not stigmatized them as genetic aberrations, no more or a priori by the fact that tortie males. It is true, some of them are genetic aberrations (XXY (Klinefelter syndrome), XXXY, XOY (Turner syndrome) ...) and can present problems, but others, especially the fertile and healthy, are suitable for breeding since you only have a few moles and others are chimeras. Those who are sterile, they already are and pose no threat to the continuity of the breed, or cats themselves, but it may be recommended the animal is castrated, either by having uncomfortable sexual behavior (marking, jealousy, aggression) both for them, as well as humans with whom they live, or have other problems that should be treated by specialists.
It is a male Norwegian Forest close descendant of Pan's Trulls, born in 1983, color and black tortoise mackerel tabby (NFO f 23)., See pedigree in Paw Peds. It might seem a genetically red cat with a somatic mutation, as it was red tabby with a black spot on the side, but his line was studied. With a black female has given black females, and females tortoise, indicating that he conveyed both colors to their offspring. It is known that the line Trippel, tortoise produces fertile males, each third generation long, and sometimes each second generation. Previous studies on this line of tortoise males, observing the phenotype, suggesting that no remains of Klinefelter syndrome, since males are always infertile tortoise. This indicates that there is more fertile male tortoise was believed that on the lines of NFO, and is not insane genetic aberrations that should be eliminated from breeding.
Se* Ulton Tigressan`s
Ulton born in 1999 in the cattery S * Tigressan`s. It was creamy silver (es 09 22) at birth, but at its front left leg was blue color spot, which rose to grow, and ended up having foot blue and other blue spots He struggled to be registered as a cat blue tortie silver (gs), but finally got it (see pedigree on line). Genetic tests were performed in Uppsala (Sweden). He had 38 chromosomes (which are normal to have the cat), and also the professor who carried out the test knew a case of another tortie male with 38 chromosomes in the same line. According to that professor, Ulton was a chimera. The only seed that is known has been all red color. It was crossed with a female red silver color, and they were red silver. It is not known much more of their offspring, or the results of tests have been done a posteriori. Carina Olofsson told us personally that two of the daughters of Ulton have lived happily without health problems and even grow old, and they stayed close to their environment and was able to follow them. Carina Thanks for your kindness! :).
Patchouli and Neroli d'Abelia * FR
In 2001 in the French cattery d'Abelia was born a litter of black silver tortie mother with white (NFO fs 09) and blue mackerel tabby with white male. Two of the females were torties two Patchouli was bicolor black tortie (NFO f 03) and Neroli blue tortie with white (NFO g 09), but soon could see actually both were males. Neroli at 11 months became father of 3 babies, 1 blue girl and 2 blue children, so he just gave the color black (with diluted) to his offspring. Patchouli was a German cattery, and there had litters with a blue female tabby mackerel with white, his sons were four babies, two males and two females. Females were two torties, one blue and one black, so that the color that gave their children was red, but there is a daughter, De Smilo Don Fátima, which is black with white (NFO n 09) who crossed with a black tabby mackerel female (NFO n 23), so he could give both colors to their offspring. Both cases are chimeras, have healthy offspring, in fact, today, in 2014, was born a female descendant of Patchouli (Quintessa Troll of Frozen Forest). Both were chimeras, and Patchouli produced sperm of the two individuals fusionarion in the womb of his mother.
Lugdush Rivendell's Land * PT
Lugdush born in the cattery of Rivendell's Land, in Portugal in 2014. Initially it was born blue, but over time realized that had spots cream colored. Finally, in an exhibition the FIFe was accepted as male NFO g 22, a a blue tortie blotched male Soon it will be castrated. Thanks to Ana and Emilio, breeders in Rivendell's Land, we can reproduce some pictures of this beauty. You can see his pedigree here: Paw Peds.Thanks Anne and Emilio for your kindness and for giving us these photos of Lugdush so cool! ;).
Arin Bosques del Zar * ES
Arin is a black tortie male with white (f 09), born in Spain in 2014. The veterinarian has confirmed that he has normal male genitalia, but nevertheless have two colors and white of the S gene currently has eight months and it develops normally, he has shown no sign of illness or mental problems. We do not know if is going to be fertile or not, time will tell. Its owner has decided for now to keep it as is, since there is no scientific evidence to indicate that it is dangerous to their health or for breeding him to continue entire. We also know, that has not shown signs of mental retardation, and should be a genetic defect (XXY, Klinefelter syndrome), it will not be fertile and not a threat to the breed. According to Sarah Hartwell, the color pattern may indicate Arin to be fertile, it is a chimera because it has complete red areas, and other very large black color. Should not be fertile, the chances are greater, and that it is a genetic anomaly, a case of hemafroditisme with internal female gonads, a masculinized female ... but is not yet known. .Elvira Marin Thanks for allowing us these beautiful pictures of Arin and your kindness! :).
To see more pics: Arin's Gallery.
As a curiosity, or coincidence, Arin is the son of Lokai Eilodon * ES, which is descended from Gomorran`s King Kreole . You can see the pedigree of Arin: Paw Peds.
Nick on Fire Bjøernpote. *De
A last case born February 27, 2015, Nick on Fire Bjøernpote *De a black tortie blotched tabby male (NFO f 22) Born in Germany in the cattery Bjørnpote *De, whose breeder is Birgit Lintl. It also has in its lines to Gomorran`s King Kreole and his sister Gomorran`s Karanda, which are two of the Norwegian Forest that descend many of the tortie males on NFO, see the pedigree Nick on Fire Bjøernpote *De. Birgit thanks for your kindness to let us to introduce Nick on Fire :D.
There are several instances in which there are several fertile tortie males in the same line coming from the same male. If over born in 2014 and 2015 two new tortie males like Patchouli, from the same line ... Is it worth castrate or wait to see if they are fertile?. It would be interesting to see what they are, and if Arin and Nick on Fire are chimeras or not. Perhaps with they consider whether they can chimerism is something that Is genetically affected and is heritable. What do you think?.
Other Tortie Males
We recommend reading the article about: Tortie Males in NFO. Study of pedigrees, it can be found more cases and the explanation of this line of tortie males.
Lilienvald's Lurifax NFO f 22. Fertile with offspring. Trippel line.
Torvmyra's Super Spot Blue NFO gs 09 23. with offspring.
Drakborgens Pehr Crääm von Frääz NFO fs 09 24, no offspring.
E T Gyldenløve NFO f 09 23, no offspring..
Zimexis Caleb Marie Mandrake NFO g 09 22, no offspring.. It comes from the same line Gomorran's King Kreole, just his sister's from father and mother Gomorran's Karandra.
We have noticed that Tripple, which is tortie male has produced a line of tortoise males studied, Torvmyra's Super Spot Blue, and all descendants of Gomorran's King kreole or his sister Karandra they have on their ancestors at Maxie, so it may be that this female cat foundation (or her unknown couple) produces fertile tortie males.
Useful genetic courses: