The Satin Gene
Tennessee Rex with curly satin coats
We have had the wonderful opportunity to be involved with the Tennessee Rex Breeding program since early 2017. We have noted a few things we would like to share. Our discussion is based on our experience with the cats we have in our home, the litters born at our home, and discussion with other Tennessee Rex Breeders.
In the beginning, our information about the Tennessee Rex was compiled from people involved in the original project, reports from the geneticist that was involved in the beginning, and from TICA members that had knowledge of the Tennessee Rex.
Our belief is that the Tennessee Rex has a genetic modification that causes a curly hair coat (Rex) and hair shafts that reflect light (Satin). The gene has been called recessive and that it was linked. In other words, there has never been a Tennessee Rex born with curly hair that also did not have the Satin. There has been more than one litter born from two parents that neither appeared to express Satin or Rex that had a kittens that expressed Satin and Rex together. The litter confirmed that the gene is recessive.
There has been some speculation that the Satin hair coat described in the Tennessee Rex was related to the gene that causes Glitter in the Bengal cats. We have been informed that the Glitter gene in the Bengal cat acts as a recessive trait. We wanted to prove or disprove the hypothesis that glitter and satin are the same or related. The thought we had is: If the glitter gene was recessive and the satin gene is recessive, then breeding a Tennessee Rex with a Bengal that had high glitter would either produce all shiny coat kittens if they were related, or no shiny coat kittens if they were not related (compatible). We have a litter which has a sire that is a Tennessee Rex with curls and Satin and a dam that is a Bengal with high amounts of glitter. The kittens born all have shiny hair coats, although not as shiny as either the Bengal or the Tennessee Rex parent. They are now 13 weeks old and still have shiny hair coats. However we have noted that some of the shine has disappeared with age on these kittens, or perhaps it is just difficult to see due to their patterns. These kittens are all altered. None were added to either parent breed. This was a test mating to try to learn more of the gene, not to cross these breeds for future matings. The Bengal dam has also been altered as we will not be repeating the breeding.
Once we saw the litter, we thought the genes for glitter and the genes for satin had to be related or even the same gene. During this time however, we had another cat have a litter. This litter had a sire that was a normal coated, non-shiny coated domestic shorthair cat and a dam that was a Tennessee Rex with Curls and excessive Satin. The litter all had no curls, but shiny hair coats. The kittens are now 12 weeks old with the hair still having the shiny appearance, although not the amount of the full expression Tennessee Rex mother (a rough estimate is they are showing 30-50% the amount of shine as their excessive satin mother). Franklin Whittenburg, the founder and originator of the Tennessee Rex Breed, came to observe these two litters of kittens. He stated that they did not have the Satin that the Tennessee Rex kittens born in his cattery had, but there was some shine to the kittens that he did not expect from a recessive trait.
After talking with a couple of other breeders that have observed Tennessee Rex kittens, it has been discussed that some kittens born in litters in their catteries from a domestic shorthair parent and a Tennessee Rex parent with curls and satin have no curls but express Satin. These discussions strengthen the hypothesis of the Satin gene expressing in kittens that should be carriers of the gene, and therefore not displaying the gene visually.
There is a gene in mice that expresses as Satin. In the information on a mouse site: http://www.hiiret.fi/eng/breeding/?pg=5&sub=9 the gene that is called Sal exhibits a very similar effect. On the website it states that the gene expresses as recessive, but on occasion the heterozygous mouse will have some expression. These Tennessee Rex F1 kittens are heterozygous for the Satin. The Satin that is being expresses is not as prominent as in the homozygous Tennessee Rex. Therefore, we may be seeing the same effect that mouse breeders are observing in their form of Satin.
Originally, with the data collected from 2004 to 2009, the Tennessee Rex gene variation was a tied entity that would produce the rexing and the satin as a recessive trait on the cats. With multiple litters born and test matings performed, the data suggested that the rexing and the satin could not be separated and were tied together to one gene or very closely related genes. There are only two litters from our cattery, and there are only two other breeders reporting the kittens with satin in a litter with one domestic parent; but there is evidence that the satin from the Tennessee Rex is somehow expressing in kittens that should be carriers of the rexing gene and the satin gene.
Since the Bengal gene is reported as being recessive, the litters indicate that the satin gene is expressing independently of the glitter gene. Much more research needs to be done on the Tennessee Rex and the satin shine they express. Until more information is gathered, the idea of the satin being recessive with the rex gene may have to be placed on the sidelines.
Again, these are just our observations! We are not stating an opinion one way or the other, we are simply sharing knowledge and observations as we continue to work. At this time we are thinking through possible "working theories", but many more litters will need to be observed in Tennessee Rex breeding programs before we can truly have enough data as a group to know how these genes work.
We have included some interesting images of hair under the microscope that we have taken as well. We are not experts on hair shafts, we simply thought they were interesting and other may enjoy them. Again, we are not making claims, just sharing what we have found. We look forward to leaning more about the gene through the efforts of all the breeders and through the DNA research in the future!
Dr. & Mrs. Gobble
Kittens from a mating between a Tennessee Rex and a glittered Bengal showing a certain amount of shine or low level satin
Kittens from a mating between a Tennessee Rex and a Domestic Longhair showing a certain amount of shine or low level satin
Microscope photos showing structure and pigment distribution of different hair types
In this series of photos the normal hair of the domestic cat has a relatively solid core of pigment. The Tennessee Rex hairs appear to have loose, irregular bands of pigment while the glittered Bengal has a more orderly tightly packed succession of granules of pigment forming a rather narrow core. The kittens from the mating between a Tennessee Rex and a glittered Bengal have a structure which appears to be more similar to the Bengal with a more orderly succession of pigment granules, perhaps packed in a less narrow core. The kittens from the mating between a Tennessee Rex and a Domestic Longhair have a more dense core of pigment, closer to that seen in the Domestic Longhair, but still displaying a succession of very tightly packed pigment granules.
This is an amateur analysis and we would welcome comments on these photos from other observers.