MisterMiceGuy

The Long Hair Genes

MisterMiceGuy has always been enamored with long haired animals and mice are no

Pied Recessive Yellow mouse with long hair (Photo Credit: MisterMiceGuy)

exception. In fact is seems that long haired mice are very popular among pet owners and hobby breeders in general (The Finnish Mouse Club 2020). Because of this MisterMiceGuy is incorporating long haired genes into his line of mice.

There may actually be many genes influencing the length of a mouse’s coat (The Finnish Mouse Club 2020). The gene at play for hobbyist mice seems to be mutations of Fibroblast growth factor 5 gene (FGF5)(The Finnish Mouse Club 2020, Hébert, Rosenquist, Götz, and Marin 1994). Fibroblast Growth Factor 5 (Fgf5) is found on the outer root sheath of hair follicles during the anagen VI phase, which is a phase of hair follicle growth. The FGF5 protein serves to inhibits the elongation of the hair shaft and induces that start of the catagen phase of the hair cycle (Hébert, Rosenquist, Götz, and Marin 1994, and Ota et al. 2002) . In fgf5^neo this growth factor seems to be reduced allowing for increased hair length (Hébert, Rosenquist, Götz, and Marin 1994).

Illustration of the hair growth cycle in humans. FGF5 protein reduces time spent in the anagen phase and decreases hair length (Photo Credit: Capillus 2017)

According to The Finnish Mouse Club (2020) there is also the Angora gene (go) which appears to be present in the hobby population. Phenotypically it is similar or identical to fgf5^neo. Unfortunately as it turns out angora is also recessive a mutant of the FGF5 gene meaning that mice with fgf5^neo and fgf5^go do not result in augmented hair length when bred together (Hébert, Rosenquist, Götz, and Marin 1994).

It appears that there may be other long hair genes that either are not common or do not exist at all in the hobby population and some of these include, lgh, Fgf5tm1Mrt, skc6, and skc8 genes (The Finnish Mouse Club 2020)

Based personal experience MisterMiceGuy suspects that there are even more additional factors affecting coat length. In mice, coat length reduces with age which may indicate an increased production of FGF5 protein with age. Additionally it seems that there is some difference between guard hairs and undercoat as some mice have very long guard hairs but an average undercoat. Anothing thing that MisterMiceGuy has noticed is that there are differences between hair density which seems unrelated to hair length but effects the overall appearance of the mouse’s coat.

References

Capillus (2017) Understanding Hair Growth Stages. Retrieved from: http://www.capillus.com/blog/understanding-hair-growth-stages

Hébert, J., Rosenquist, T., Götz, J., and Marin, G. (1994) FGF5 as a regulator of the hair growth cycle: Evidence from targeted and spontaneous mutations. Cell, (78)6, 1017-1025.

The Finnish Mouse Club (2020) Varieties. Retrieved from: http://www.hiiret.fi/eng/breeding/?pg=4&sub=11&ala=8

Ota, Y., Saitoh, Y., Suzuki, S., Ozawa, K., Kawano, M., and Imamura, T. (2002). Fibroblast growth factor 5 inhibits hair growth by blocking dermal papilla cell activation. Biochemical and Biophysical Research Communications. 290(1), 169-76.

Pink-Eyed Dilution Gene

The first documented version of the pink-eyed dilution mutation is believed to come from Asia and today there are over 100 documented varieties. Some of them occurred due to spontaneous natural mutations while others were induced mutations by means of x-ray or chemical mutagens. The genes occur on chromosome 7 and its referred to as the P-locus (Brilliant, Ching, Nakatsu, and Eicher 1994). The version of P-locus gene that is present in the fancy mouse hobby is simply called “Pink-Eye Dilution” (p). This is reported to be the oldest and most common version of the gene (Silvers 1979).

A common feature among these P-locus genes is a reduction in coat color and eye color pigment. Depending on the version of the gene this effect can be minor or extreme. Although the pink-eye effect can appear similar to that of C-locus genes, such as albino or siamese, but the genes are different and occur at a different locus (The Finnish Mouse Club 2020, Brilliant, Ching, Nakatsu, and Eicher 1994).

The genotype for homozygous pink eye is “p/p” but this is always combined with other coat color genes and produces a variety of phenotypes (American Fancy Rat and Mouse Association 2019).

MisterMiceGuy’s original Pink-eyed Mouse (MisterMiceGuy 2019).

Another thing to keep in mind that different Fancy Mouse Clubs may use different terms to describe a phenotype even though the genotype may be the same. For example mice that have the pink-eyed black genotype (aa pp) may be referred to as Dove, Lilac (The Finnish Mouse Club 2020) or blue lilac (Silvers 1979). Conversely, sometimes a phenotype name may be used regardless of the mouses genotype (Fance Mouse Breeders Association 2020).

Some common phenotype names that involve the pink-eye dilution gene include Dove, Pink-eyed Dove, Lilac, Blue Lilac, Silver, Pink-eyed Blue, champagne, Cream, Chinchillated Dove, Lavender, Orange, Argente, Blue Argente, Argnete Creme, Pink-eyed Fawn, Cinnamon, Fawn, or White. Pink-Eye Dilution gene can also accompany any variety of marking such as pied, spashed, broken, hereford, head spot, rumpwhite, merle, roan or any variety of coat type such as nude, angora, texel, or frizzie (Fance Mouse Breeders Association 2020, Silvers 1979, The Finnish Mouse Club 2020, American Fancy Rat and Mouse Association 2019).

This is a port from an older article I wrote and may need updating

References

Brilliant, M., Ching, A., Nakatsu, Y, and Eicher, E. (1994) The Original Pink-Eyed Dilution Mutation (p ) Arose in Asiatic Mice: Implications for the H4 Minor Histocompatibility Antigen, Myodl Regulation and the Origin of Inbred Strains. Genetics, 138, 203-211

Silvers, W. (1979) The Coat Colors of Mice: A Model for Mammalian Gene Action and Interaction. Springer Verlag, Retrieved from: http://www.informatics.jax.org/wksilvers/index.shtml

American Fancy Rat and Mouse Association (2019) Fancy Mouse Genes, Alphabetical Name Listing, Retireved from: https://www.afrma.org/geneticsblackmse.htm

The Finnish Mouse Club (2020) P-locus. Retrieved from: http://www.hiiret.fi/eng/breeding/?pg=5&sub=7

Fancy Mouse Breeder’s Association (2020) Show Standards. Retrieved from: http://www.fmbamice.com/show-standards/

The Himalayan Gene

The Himalayan gene produces a phenotype characterized by having a light-colored or white body with dark extremities. The phenotype is sometimes also known as “Siamese” and is seen is species such as rabbits, cats, guinea pigs, and hamsters. (Green, n.d.)

Reportedly, an early or possibly the first description of a mouse with the appearance of the Himalayan gene was recorded in 1939 on a German island by E. Mohr. However, I have not been able to access this German reference. Another mouse that had a wildtype color but slowly changed into a Himalayan appearance after about five months of age was described but it did not produce any offspring that possessed the trait (Dickie, 1944).

Subsequently, (Green, n.d.). described the appearance of what appears to be the Himalayan gene in the mouse hobby. It occurred in a litter of seven pups produced at the Jackson Memorial Laboratory and identified by Madeline Jewett. They describe the phenotype as starting white, like an albino, but the points become progressively darker with each molt. The darkness of the points is also described as being temperature-sensitive. Additionally, the eyes are described as unpigmented at birth but becoming progressively darker with age and are ruby colored at weaning. Testing breeding at the time proved that the Himalayan gene was a c-series albino gene, and it was given the symbol c^h (Green, n.d.).

It’s possible, in fact it’s likely, that the Himalayan gene in mice causes alterations in brain development and in the neural projections coming from the retina causing an altered visual perception, possibly loss of depth perception (Jeffery et al., 1994; Kaas, 2005). However, it should be noted that while mice do normally possess binocular depth perception (Boone et al., 2021), the loss of it might not be obvious just as it’s not obvious in domestic cats (Kaas, n.d.).

References

Jeffery, g, Schuts, g, & Montolu, l. (1994). Correction of abnormal retinal pathways found with albinism by introduction of a functional tyrosinase gene in transgenic mice. Developmental Biology, 166, 460–464.

Boone, H. C., Samonds, J. M., Crouse, E. C., Barr, C., Priebe, N. J., & McGee, A. W. (2021). Natural binocular depth discrimination behavior in mice explained by visual cortical activity. Current Biology, 31(10), 2191-2198.e3. https://doi.org/10.1016/j.cub.2021.02.031

Dickie, M. M. (1944). A UNIQUE “HIMALAYAN” MOUSE. Journal of Heredity . https://academic.oup.com/jhered/article/36/9/265/872245

Green, M. C. (n.d.). HIMALAYAN, A NEW ALLELE OF ALBINO IN THE MOUSE HIMALAYAN MOUSE. https://academic.oup.com/jhered/article/52/2/73/757038

Kaas, J. H. (2005). Serendipity and the Siamese Cat: The Discovery That Genes for Coat and Eye Pigment Affect the Brain. ILAR Journal, 46(5). https://academic.oup.com/ilarjournal/article/46/4/357/656824

New Mice, Welcome Back!

MisterMiceGuy was on a haitus due to graduate but is back with some new mice! I’ve explored a bunch of different options as far as goals and branding but I decided to stay with the MisterMiceGuy brand and theming.

Pictured above are the first generation of new mice. The male is an Angora Brindle and the female is an unmarked pink-eyed Angora Brindle. I have high hopes that this will be the start of new growth of MisterMiceGuy as a business and start of much science-based educational content going forward!

I will be active off on and on but I plan on starting to produce more mouse based content similar to what I was doing in the past. However, going forward MisterMiceGuy will be expanding to include mouse content that is more explicitly educational in nature. I will also be producing a variety of other educational resources and materials.