Nude rats are characterized by a strong Hypotrichiose, d.h. lack of hair, out. This may be more or less reduced. Some animals have facial hair and bristly hairs on the back, others are completely naked. The expression of vibrissae is very different. This is because, that there is no "the" Naked rat. Rather, various mutations and lines are grouped together under this term. It should be noted, that common in the grown as pets Rats do not know, which mutation of nudity is based. Although some sources indicate, that the RNU locus is responsible for nudity, There are various other Loki, eligible. Some of them are not even clarified in laboratory lines and without proper tests, it can not close the underlying genetics of the lack of hair.
recessive mutation over a dozen in total have already been described, trigger hypotrichosis in rats (reviewed by Ferguson e al. 19791)Ferguson FG, Irving GW III, and Stedham MA, 1979. Three variations of hairlessness associated with albi- nism in the laboratory rat. Lab Anim Sci 29:459–465, Hanada et al. 19882)Hanada K, Chiyoya S, and Suzuki K, 1988. Study of the skin of a new hairless rat mutant. J Dermatol Surg On-col 15:257–262 , Hedrich 1990 3)Hedrich HJ, 1990. Mutant genes and polymorphic loci of the laboratory rat. In: Genetic monitoring of inbred strains of rats ( Hedrich HJ, ed). New York: Gustav Fischer Verlag; 289–409, Moemeka et al. 19984)Moemeka AN, Hildebrandt AL, Radaskiewicz P, and King TR, 1998. Shorn (shn): a new mutation causing hypotrichosis in the Norway rat. J Hered 89:257–260., Robinson 19795)Robinson R, 1979. Taxonomy and genetics. In: The laboratory rat ( Baker HJ, Lindsey JR, and Weisbroth SH, eds). New York: Academic Press; 37–54.).
Some examples of laboratory strains:
Sprague Dawley Hairless
(Rj:SDH-Dsg4, SPRAGUE DAWLEY® is a trademark of Harlan. All rights reserved.)
The SPRAGUE DAWLEY® descendant from a colony, the 1925 R. W. Founded DAWLEY and reared in the Sprague-Dawley farm. The mutation "Hairless" has appeared in a colony of Sprague-Dawley, and 2004 have Bazzi et al. the development of hair follicles in individuals, having this phenotype "without hair", examined. Die „Hairless“- Rats have hair with a "gooseneck" aspect, which is also called lanceolate. this characteristic, which has a similarity with the other hair growth Rodents, hat Bazzi et al. brought to, to investigate the gene involved in this phenomenon. In the course of this work, the gene was desmoglein 4 (Dsg4), on chromosome 18 situated, identified. A deletion of 9 Exons was demonstrated in this gene. The DSG4 one of the cadherins, Glycoproteinen, which are involved in the process of adhesion of the cells, the mechanisms of the integrity and stability of the epithelial cells. The observed gene mutation at DSG4 would thus the extracellular interactions of the protein interfere with a fixation problem of calcium on the receiving point of the calcium ion. An anomaly in the first stages of morphogenesis of the hair follicle was observed. However, it seems, that strong impairment of the next stages are given, in terms of internal Epithelhülle and the emergence of the hair shafts and mainly due to a poor proliferation of hair matrix and an abnormal differentiation in the Präkortexzone. This leads to a reduction in the hair bulb and form a dysmorphia of the hair shafts.
The carriers of this mutation have abnormalities in hair- and facial hair as well as in thickening of the epidermis, but preserve a functioning immune system (Immunokompetenz). The "Hairless" -Anblick emerged with the age of 4 weeks, before it by the age of 8-9 Weeks to permanently. The homozygous females have an error during lactation on. (Those: Jnvir-Labs)
LOU Nude (RNU-Mutation)
In year 1970 have H. BAZIN and A. BECKERS started with the breeding of LOU rats, probably from a Wistar colony of the University of Liege (Belgium) come. were of this breed 28 Selected lines parallel: LOU / C because of their high content of plasmocytes and LOU / M because of their low content of plasmocytes.
In year 1953 the nude rats have appeared for the first time in an outbred colony of hooded rats at the Rowett Research Institute in Aberdeen, Scotland. But no precaution was taken at this time, to isolate the mutation. In the 70s, the mutation in the same colony has resurfaced (May et al., 1977; Festing et al., 1978). The researchers have found, that the mutation was obtained in the colony, but with a low frequency.
For the recessive autosomal mutation, the abbreviation stands for rnu Rowett nude. Das Institut Pasteur in Lille (IPL) has the mutation in collaboration with M. CAPRON und M. BASIN (1977) acquired. In the year 1993 The IPL has decided, to transfer the mutation by repeated backcrossing to the background LOU / M.
spontaneous Mutation rnu concerns the GenFoxn1(forkheadboxN1) on chromosome 10, encoding the Foxn1 for a transcription factor (also Whn: called winged-helix-nude). The Foxn1 regulates expression of the Keratingens and turns in the growth and differentiation of thymus cells.
The Mutation rnu is related to the absence of hair and an aplasia of the thymus:
- „Hairless“-Charakter (lights Hair inventory possible): The rat Foxn1rnu / Foxn1rnu has some short and fine hair on, the hair follicle sind normal, but their keratinization is damaged and the hair does not come out. Keratinization of the epidermis is also damaged.
- Immunologischer Status: The most important characteristic is a congenital aplasia of the thymus, which remains present in rudimentary form without population of lymphocyte cells (Fosse et al., 1980; Vos et al., 1980). This deficiency is reflected in the absence of T lymphocytes; however, the B-lymphocytes remain functional.
- The nude females have a growth defects of the mammary glands and are unable, to suckle their young (Guillaumot, 1986).
- The heterozygous animals Foxn1rnu / Foxn1 + show partial expression of the phenotype rnu.
Between the presence of temporary vellus and the degree of immunodepression no correlation described.
RNU Rat (Charles River)
A spontaneous mutation in a Crl:CD(D) Colony at Charles River in the late 1980s. These rats do not feed the typical characteristics of hair growth and loss as other hairless models. So far there have been no specific genetic tests, to identify the mutation. (Those: Criver)
Hirosaki Hairless Rat
This mutation occurred spontaneously in a stock of Sprague Dawley rats. The locus for the responsible gene was determined by linkage analysis and mapped to the chromosome 7q36. Since many basic Keartin genes occur at this location together, Wirde their expression examined. Show reverse transcription PCR and genomic PCR, that the genes, encode the basic keratins, are not expressed. (Nanashima et al. 20086)Naoki Nanashima, Miki Akita, Toshiyuki Yamada, Takeshi Shimizu, Hajime Nakano, Yang Fan & Shigeki Tsuchida (2008) The Hairless Phenotype of the Hirosaki Hairless Rat Is Due to the Deletion of an 80-kb Genomic DNA Containing Five Basic Keratin Genes, The Journal of Biological Chemistry, 283, 16868-16875).
Robinson describes in his book "Genetics of the Norway Rat" two forms of Hypotrichose.
Naked was first Castle, Dempster and Shurrager (1955) described. The Naked Animals were already grounded identififiziert at birth on the basis of bent Vibrissae. They were given a thin coat youth, lost that but again up to the age of 3 Partial week a fine downy hair at the age of formed 4 weeks, then got lost again. after about. 6 Months, the animals were mostly completely naked. The mothers often had Laktationsprobleme.
Naked the allele is n accepted as a basis. There is evidence, that hr and n is a linkage group on the 3. form chromosomes (Castle, 19557)(W. E. CASTLE (1955) FURTHER STUDIES OF LINKAGE IN THE THIRD CHROMOSOME OF THE RAT (1955), Journal of Heredity, Volume 46, Issue 2, March 1955, Pages 84–86).
Charles River Hairless
Meanwhile, a further gene was next hr and n discovered, that effect in the form of a Hypotrichiose. The Charles River hairless mutation is on the chromosome 1 near Myl2, D1Rat219, -287 and -438 and is likely allelic to Fuzz (fz). It is homologous to the chromosome 7 in mice, on which the recessive Frizzy (fr) Mutation is located (Ahearn et al., 20028)(Ahearn K1, Akkouris G, Berry PR, Chrissluis RR, Crooks IM, dull AK, Grable S, Jeruzal J, Lanza J, C Lavoie, Maloney RA, Pitruzzello M, Sharma R, Stoklasek TE, Tweeddale J, King TR. (2002) The Charles River "hairless" rat mutation maps to chromosome 1: allelic with fuzzy and a likely orthologue of mouse frizzy. J Hered. 2002 May-Jun;93(3):210-3).
The standard of the nude rat
The American Fancy Rat and Mouse Society describes in her standard of 9.10.1994 the Hairless as follows:
Hairless rats should a thin, bright, almost translucent skin have free of scars or pimples. The skin can be any color or recognized badge, Wrinkles should not be penalized. The eyes can have any color, but should be bright and free of any problems. The ears should be very large and wrinkle-free. The vibrissae can be very short or absent, They are usually curled.
In the German standard of color rat nude rats are explicitly excluded.
References [ + ]
|1.||↑||Ferguson FG, Irving GW III, and Stedham MA, 1979. Three variations of hairlessness associated with albi- nism in the laboratory rat. Lab Anim Sci 29:459–465|
|2.||↑||Hanada K, Chiyoya S, and Suzuki K, 1988. Study of the skin of a new hairless rat mutant. J Dermatol Surg On-col 15:257–262|
|3.||↑||Hedrich HJ, 1990. Mutant genes and polymorphic loci of the laboratory rat. In: Genetic monitoring of inbred strains of rats ( Hedrich HJ, ed). New York: Gustav Fischer Verlag; 289–409|
|4.||↑||Moemeka AN, Hildebrandt AL, Radaskiewicz P, and King TR, 1998. Shorn (shn): a new mutation causing hypotrichosis in the Norway rat. J Hered 89:257–260.|
|5.||↑||Robinson R, 1979. Taxonomy and genetics. In: The laboratory rat ( Baker HJ, Lindsey JR, and Weisbroth SH, eds). New York: Academic Press; 37–54.|
|6.||↑||Naoki Nanashima, Miki Akita, Toshiyuki Yamada, Takeshi Shimizu, Hajime Nakano, Yang Fan & Shigeki Tsuchida (2008) The Hairless Phenotype of the Hirosaki Hairless Rat Is Due to the Deletion of an 80-kb Genomic DNA Containing Five Basic Keratin Genes, The Journal of Biological Chemistry, 283, 16868-16875|
|7.||↑||(W. E. CASTLE (1955) FURTHER STUDIES OF LINKAGE IN THE THIRD CHROMOSOME OF THE RAT (1955), Journal of Heredity, Volume 46, Issue 2, March 1955, Pages 84–86|
|8.||↑||(Ahearn K1, Akkouris G, Berry PR, Chrissluis RR, Crooks IM, dull AK, Grable S, Jeruzal J, Lanza J, C Lavoie, Maloney RA, Pitruzzello M, Sharma R, Stoklasek TE, Tweeddale J, King TR. (2002) The Charles River "hairless" rat mutation maps to chromosome 1: allelic with fuzzy and a likely orthologue of mouse frizzy. J Hered. 2002 May-Jun;93(3):210-3|