Louida
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A new paper by Dr. Rebecca Bellone and seven other members of The Appaloosa Project team has just been published. Together they have determined that the gene TRPM1 (Transient Receptor Potential Cation Channel, Subfamily M, Member 1) is the gene in which the causative mutation for both Appaloosa spotting and CSNB is most likely located. Here's a link to the online publication of "Genetics":
http://www.genetics.org/cgi/content/abstract/179/4/1861
This takes you to the abstract (summary) only - the paper in its entirety is copyright protected by "Genetics" and is therefore only available if you are a subscriber to their journal. Interested readers can choose to subscribe to "Genetics" through the above link in order to obtain access to the full paper.
For those of you who just want to read the abstract, here's the text:
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Differential Gene Expression of TRPM1, the Potential Cause of Congenital Stationary Night Blindness and Coat Spotting Patterns (LP) in the Appaloosa Horse (Equus caballus)
Rebecca R. Bellone, Samantha A. Brooks, Lynne Sandmeyer, Barbara A. Murphy, George Forsyth, Sheila Archer, Ernest Bailey and Bruce Grahn
The appaloosa coat spotting pattern in horses is caused by a single incomplete dominant gene (LP). Homozygosity for LP (LP/LP) is directly associated with congenital stationary night blindness (CSNB) in Appaloosa horses. LP maps to a 6-cM region on ECA1. We investigated the relative expression of two functional candidate genes located in this LP candidate region (TRPM1 and OCA2), as well as three other linked loci (TJP1, MTMR10, and OTUD7A) by quantitative real-time RTâPCR. No large differences were found for expression levels of TJP1, MTMR10, OTUD7A, and OCA2. However, TRPM1 (Transient Receptor Potential Cation Channel, Subfamily M, Member 1) expression in the retina of homozygous appaloosa horses was 0.05% the level found in non-appaloosa horses (R = 0.0005). This constitutes a >1800-fold change (FC) decrease in TRPM1 gene expression in the retina (FC = â1870.637, P = 0.001) of CSNB-affected (LP/LP) horses. TRPM1 was also downregulated in LP/LP pigmented skin (R = 0.005, FC = â193.963, P = 0.001) and in LP/LP unpigmented skin (R = 0.003, FC = â288.686, P = 0.001) and was downregulated to a lesser extent in LP/lp unpigmented skin (R = 0.027, FC = â36.583, P = 0.001). TRP proteins are thought to have a role in controlling intracellular Ca2+ concentration. Decreased expression of TRPM1 in the eye and the skin may alter bipolar cell signaling as well as melanocyte function, thus causing both CSNB and LP in horses.
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Two of the authors are speakers at the 2008 International Knabstrupper conference in Denmark, which is to be held 12-14th September. Tickets are now on sale and are selling fast, as this is a prime opportunity for breeders of spotted horses to listen to the researchers talk about spotted coat pattern inheritance and also quiz the researchers face-to-face.....
More information on the conference is available at: http://www.knabstrupperforeningen.dk/Kna..._2008_index.htm
http://www.genetics.org/cgi/content/abstract/179/4/1861
This takes you to the abstract (summary) only - the paper in its entirety is copyright protected by "Genetics" and is therefore only available if you are a subscriber to their journal. Interested readers can choose to subscribe to "Genetics" through the above link in order to obtain access to the full paper.
For those of you who just want to read the abstract, here's the text:
---------------------------------------------------------
Differential Gene Expression of TRPM1, the Potential Cause of Congenital Stationary Night Blindness and Coat Spotting Patterns (LP) in the Appaloosa Horse (Equus caballus)
Rebecca R. Bellone, Samantha A. Brooks, Lynne Sandmeyer, Barbara A. Murphy, George Forsyth, Sheila Archer, Ernest Bailey and Bruce Grahn
The appaloosa coat spotting pattern in horses is caused by a single incomplete dominant gene (LP). Homozygosity for LP (LP/LP) is directly associated with congenital stationary night blindness (CSNB) in Appaloosa horses. LP maps to a 6-cM region on ECA1. We investigated the relative expression of two functional candidate genes located in this LP candidate region (TRPM1 and OCA2), as well as three other linked loci (TJP1, MTMR10, and OTUD7A) by quantitative real-time RTâPCR. No large differences were found for expression levels of TJP1, MTMR10, OTUD7A, and OCA2. However, TRPM1 (Transient Receptor Potential Cation Channel, Subfamily M, Member 1) expression in the retina of homozygous appaloosa horses was 0.05% the level found in non-appaloosa horses (R = 0.0005). This constitutes a >1800-fold change (FC) decrease in TRPM1 gene expression in the retina (FC = â1870.637, P = 0.001) of CSNB-affected (LP/LP) horses. TRPM1 was also downregulated in LP/LP pigmented skin (R = 0.005, FC = â193.963, P = 0.001) and in LP/LP unpigmented skin (R = 0.003, FC = â288.686, P = 0.001) and was downregulated to a lesser extent in LP/lp unpigmented skin (R = 0.027, FC = â36.583, P = 0.001). TRP proteins are thought to have a role in controlling intracellular Ca2+ concentration. Decreased expression of TRPM1 in the eye and the skin may alter bipolar cell signaling as well as melanocyte function, thus causing both CSNB and LP in horses.
-----------------------------------------------------
Two of the authors are speakers at the 2008 International Knabstrupper conference in Denmark, which is to be held 12-14th September. Tickets are now on sale and are selling fast, as this is a prime opportunity for breeders of spotted horses to listen to the researchers talk about spotted coat pattern inheritance and also quiz the researchers face-to-face.....
More information on the conference is available at: http://www.knabstrupperforeningen.dk/Kna..._2008_index.htm