Unser Haushund: Eine Spitzmaus im Wolfspelz? - Wolf-Ekkehard ...

87associated with wire hair and ''furnishings'', the latter being the moustache and eyebrowscharacteristically seen, for instance, in the schnauzer [16] (Figure 4). Long versus short fur is associatedwith a (Cys95Phe) change in exon one of the fibroblast growth factor-5 (FGF5) gene. Curly versusstraight fur is associated with a coding SNP within the keratin71 (KRT71) gene [16], as it is in mice [35].Remarkably, combinations of alleles at just these three genes account for ~ 95% of coat variationobserved among the 108 AKC breeds studied. For instance, the Bichon frise carries the variant allele forRSPO2, FGF5, and KRT71 and thus possesses long, curly hair with furnishings (Figure 4).” 154Zur 167 bp Deletion am 3' Ende des R-spondin-2 (RSPO2) Gens müssen dieAutoren in ihrer Originalarbeit für die betroffenen Hunderassenbedauerlicherweise 155 vermerken (2009, p. 151):"Fine-mapping allowed us to reduce the homozygous region to 238 kb spanning only the R-spondin–2(RSPO2) gene, excluding the 5´untranslated region (5′UTR) and the first exon (Fig. 1D, fig. S1, and tableS3). RSPO2 is an excellent candidate for a hair-growth phenotype as it synergizes with Wnt to activate ß-catenin (12), and Wnt signaling is required for the establishment of the hair follicles (13, 14). Moreover, theWnt/ß-catenin pathway is involved in the development of hair-follicle tumors, or pilomatricomas (15),which occur most frequently in breeds that have furnishings (16). Recent studies have shown that amutation in the EDAR gene, also involved in the Wnt pathway, is responsible for a coarse East-Asian hairtype found in humans (17), with some similarity to canine wirehair.”Nicht unwichtig erscheint mir auch der folgende Hinweis:"This mutation does not affect the protein-coding region of the RSPO2 gene. However, because the 3′UTRfrequently encodes elements that influence mRNA stability [reviewed in (18)], we examined whether the insertion [sic]was associated with a change in the expression level of the RSPO2 gene. We found a threefold increase in RSPO2transcripts in muzzle skin biopsies of dogs with furnishings, consistent with a transcript effect (fig. S2).”Die Autoren sprechen hier im Text der Originalarbeit einmal von "insertion" undzur Erklärung ihrer Fig. 1 (p. 151) von einer "deletion" ("A 167-bp deletion,indicated by the small red rectangle, is located within all three haplotypes in the3′UTR of the RSPO2 gene.”) und nennen das Rechteck indel (insertion/deletion).Im Review sprechen sie jedoch nur von einer Deletion und im Supporting OnlineMaterial 156 lesen wir: "Only the deletion at position 11 634 766 is perfectlyassociated with the dominant phenotype.” Der entscheidenede Punkt ist, dass essich – gemessen am Wildtyp – um eine Deletion handelt (auch wenn ein anderesAllel eine Insertion aufweist, die jedoch nicht mit dem Phänotyp assoziert werdenkonnte).Zur oben zitierten Aussage "Long versus short fur is associated with a(Cys95Phe) change in exon one of the fibroblast growth factor-5 (FGF5) gene”stellen die Autoren außerdem in ihrer Originalarbeit (2009, p. 151) fest:154 Auch das schon oben behandelte Thema Color bringen die Autorinnen ausgezeichnet wie folgt auf einen Nenner: "One additional source ofvariation, a lack of coat as seen in the Chinese crested, Mexican and Peruvian hairless breeds is explained by a frame shift mutation in FOX13,a member of the fork head box transcription factor family [36].Coat color is independent of type and is primarily governed by the melanocortin receptor (Mc1r) pathway. Variants result from mutations in theAgouti, Mc1r, and CBD103 genes, the latter of which encodes ß-defensin. A coat like that of the German shepherd contains both black andyellow pigments, termed eumelanin, and pheomelanin, respectively. Coats expressing only pheomelanin develop when Mc1r is nonfunctionaland therefore unable to produce eumelanin [37,38]. Coats expressing only eumelanin occur via two mechanisms: recessive black coats areobserved when the agouti protein is nonfunctional. Dominant black coats occur when a derived ß-defensin protein competitively inhibits theagouti protein [39,40]. Several dog breeds exhibit complete or partial absence of pigmentation. For instance, Karlsson et al. mapped a locus forwhite-spotting to a 102-kb haplotype on CFA 20 in a region that spans a single gene; microphthalmia-associated transcription factor (MITF),which is crucial for melanocyte migration [13]. Two potential mutations were identified, one of which is a SINE insertion that may disrupttranscription [13].”155 Wie oben schon erwähnt, denke ich als Hundefreund dabei sowohl an die betroffenen Tiere als auch an die 'Frauchen' und 'Herrchen', die sichoft so sehr um ihre Hunde kümmern. Was habe ich um unsere Hunde, die beide 13 ½ Jahre alt wurden, 'geheult' als sie eingeschläfert wurden(für einen Hovawartrüden übrigens ein gutes Alter).156 http://www.sciencemag.org/content/suppl/2009/08/27/1177808.DC1/Cadieu.SOM.pdf