We are with you the same wool

Exotic breeds of cats created to delight the eyes and soul of a person, scientists want to adapt to the study of diseases of his hair. In people and animals, the same genes and a mutation are responsible for the development of the hair, thanks to which the coats are curly in cats, in a person causes a pathology.

In the middle of the last century, breeders began to create several breeds of rexid cats. They are distinguished by the lack of axial hair and a soft, thin, short, wavy coat resembling a karakul or, as some say, a washing board. A mustache (vibrissa) also has curly and brittle. There are several rexidate breeds: Kornishrex, Devonks, German Rex and Selkirkrex (they are long -haired). The breeds arose regardless of different places: in Cornwall, Devonshire, East Prussia and the United States. The wool of the rexid cats was frozen as a result of the only recessive mutation in the gene located on the autosom. In Devonces, this KRT 71 is one of the genes encoding keratin hair and epithelium. Mutations in it also cause curly in mice, dogs, rats and people. When crossing Devonces with cornishreshchors and German rexes, kittens with straight hair are born; Therefore, in these breeds, curly is caused by a mutation in another gene. In which one - the specialists of the University of California (Davis) under the leadership of Dr. Leslie A. Lyons were versed.

Typically, the cat breed begins with an accidental recessive mutation. People notice an unusual animal and proceed to the selection, trying to fix the sign, that is, to ensure that all representatives of the breed are homozygous according to this mutation. For Selkirkreks and German Rexes, breeding work has not yet been completed, and in their offspring there are kittens with straight hair. The Kornishchex breed has settled, there is no split in offspring. Researchers compared the genome of 11 breeds of cats with straight wool and two independent cornichex populations. There are analysis methods that allow you to determine which sequences of the genome were selection. Scientists have found such a area specific to the Kornishchex breed on chromosome A 1 . It has 31 gene, including LPAR 6 , responsible for the quality of the wool. It encodes the protein of the receptor located on the cell membrane, including in the hair follicle. The receptor binds to lysophosphatic acid, and their interaction regulates the work of keratin genes, hair growth and the structure of the hair rod. The mutant sequence of LPAR 6 in the cornishrex contains a small deed, leading to a shift in the reader and the formation of stopcodon. As a result, the protein is so short that it is hardly possible to perform the functions of the receptor. The same mutation was found in two irreparable cats with wavy wool and German rex (when crossing these two breeds, curly kittens are born). In cats with straight wool, a mutation, if it occurs, is only in heterozygot.

In humans, LPAR 6 is located on the 13th chromosome; Replacements, inserts and deletions in this generate hair wool (they are short, tightly curled and easily split), as well as to hypotrichosis - diffuse progressive hair loss. In people, woolly hair and hypotrichosis are usually connected. In the cornichens, the wool is quite thick, although the structure of the LPAR 6 receptor is very strong. Perhaps the fact is that the genetic background in the cells of cat follicles is different than a person, or there are other reasons: the role of the protein LPAR 6 is not yet finally determined.

In addition to the wavy wool, the cornishrexes have other characteristic features, such as white spots on the skin, a special shape of the head and ears, a specific physique. All genes related to them have to identify and study. But now researchers are most interested in the search for genes, mutations in which are caused by hereditary hair diseases in animals and people. Scientists suggest using cats as a model to study these pathologies.

Perhaps the cats themselves would prefer another object of research: mice and fish are suitable for this purpose no worse.

On mice, for example, you can examine hypohydodermal dysplasia, a disease in which people are devoid of teeth and hair on the body, and their skin is thin and dry. For these disorders, genes encoding transmembrane protein ectodisplasin (EDA) and connecting its EDAR receptor.

Tabby mutations are described in mice, which causes only one of the four types of hair, as well as teeth defects. Tabby gene It turned out to be a homologous human Gene EDA , which regulates the formation of ectoderm derivatives, that is, hair, teeth and sweat glands. Another mutation, downless , outwardly indistinguishable from Tabby , affects the Edar gene. Mutations in genes that impede the growth of hair in humans interfere with the development of wool in mice, but, even more surprisingly, they are also responsible for the formation of scales in bony fish.

Although the scales of bony fish are a derivative of ectoderm, like hair, it differs from them in structure. Hair (and feathers) contain keratin and descended from keratinized epidermal scales of a common ancestor of mammals and reptiles. There is no keratin in scales in scales, but there is dentin and enamel that is related to the teeth of mammals and skin armor, covering the body of the ancient vertebrates. There is even a hypothesis according to which the teeth came from fragments containing a dentin of armor that moved to the oral cavity.

Japanese researchers, led by Professor Tokyo University Akihiro Sima (Akihiro Shima) described Medaki fish ( Oryzias Latipes ) RS 3 (Reduced Scale3), which prevents the development of scales.

Mutant fish are almost completely bald, they have no other visible violations. RS 3 is a recessive mutation that arose as a result of embedding the transposon into the Edar gene. The spoiled gene does not work, and scales in fish are formed only from those cells in which protein is synthesized. In mammals, defective in the Edar gene, the development of teeth is impaired, however, in RS 3 mutants in perfect order. Medak also has other mutations that cause defects in the scales, and it would be interesting to investigate them in detail.

The authors of the work first proved that the formation of fish scales and the growth of the hair of vertebrates is controlled by the same gene. They believe that Edar Determines the development of all derivatives of the epithelium in vertebrates. Therefore, in Japanese honey, you can study the development of hair in mammals. And since this fish is small and multiplies quickly, it should be more convenient to work with it than with a cat.

Another bald fish, a three -ligated thorny gasterosteus Aculeatus gave us a mutation in the Eda gene . Initially, the priest was found at sea, but after melting the glaciers settled the fresh reservoirs. Now there are two of its subspecies: marine and freshwater. 32–36 strong records are covered with the back of the head to the tail to the tail, and in the freshwater populations of their no more than 9. Specialists of the University of Stanford (USA) and the University of British Colombia (Canada) found that the loss of plates was caused by a mutation leading to a change in the amino acid sequence of exodisplasinaa.

In almost all freshwater populations of the northern hemisphere of the EDA mutation Almost identical. However, it is unlikely that these populations scattered around the world have a common ancestor: for this, the fishball caps would have to plow the ocean full of sea pricems with a full set of spinal plates. It turned out that mutant alleles Eda With a small frequency, they are found in the populations of the sea strip and, apparently, repeatedly and independently recorded from the inhabitants of different fresh water bodies.

In mammals in EDA mutations They are rare and always cause pathologies. Why are they everywhere widespread in freshwater pricks? According to the researchers, the fact is that in hairless mammals the gene is lost almost completely and non -functional, and in fish it only changed the sequence. Probably, mutant protein gives fish advantages that outweigh the unpleasant consequences of baldness. It is known, for example, that changes in the EDA sequence They affect the regulation of the work of other genes, including those responsible for myelinization and the speed of the signal, hearing, skin thickness and excretion of salt, so that the strips were able to master the fresh reservoirs. In addition, they are less susceptible to parasites than marine. So bald heads are not always evil, and mammals can know this truth only by studying fish.

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