| 1. |
- Andersson, Lisa, et al.
(författare)
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Mutations in DMRT3 affect locomotion in horses and spinal circuit function in mice
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 488:7413, s. 642-646
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Tidskriftsartikel (refereegranskat)abstract
- Locomotion in mammals relies on a central pattern-generating circuitry of spinal interneurons established during development that coordinates limb movement(1). These networks produce left-right alternation of limbs as well as coordinated activation of flexor and extensor muscles(2). Here we show that a premature stop codon in the DMRT3 gene has a major effect on the pattern of locomotion in horses. The mutation is permissive for the ability to perform alternate gaits and has a favourable effect on harness racing performance. Examination of wild-type and Dmrt3-null mice demonstrates that Dmrt3 is expressed in the dI6 subdivision of spinal cord neurons, takes part in neuronal specification within this subdivision, and is critical for the normal development of a coordinated locomotor network controlling limb movements. Our discovery positions Dmrt3 in a pivotal role for configuring the spinal circuits controlling stride in vertebrates. The DMRT3 mutation has had a major effect on the diversification of the domestic horse, as the altered gait characteristics of a number of breeds apparently require this mutation.
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| 2. |
- Fegraeus, K. Jaderkvist, et al.
(författare)
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Different DMRT3 Genotypes Are Best Adapted for Harness Racing and Riding in Finnhorses
- 2015
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 106:6, s. 734-740
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies showed a positive effect of the DMRT3 "gait keeper" mutation on harness racing performance in Standardbreds, French-, and Nordic trotters. The mutation has also been shown to influence riding traits in multiple breeds. This study investigated the effect of the DMRT3 mutation on harness racing performance and riding traits in Finnhorses. Finnhorses used for harness racing (n = 180) and for riding (n = 59) were genotyped for the DMRT3 mutation. For the trotters the genotypes were evaluated for association with racing performance (number of starts, victories, placings, earnings, and race times). At 3-6 years of age the AA genotype was superior compared with the CA and CC genotypes. The AA horses had a significantly higher proportion of victories (P = 1.4 x 10(-6)) and placings (P = 4.1 x 10(-7)), better race times (P = 0.01), and earned more money (P = 0.009) compared with C-horses. For the Finnhorses used for riding the owners answered a questionnaire to score how well the horse performed the gaits walk, trot, and canter on a scale from 1 to 6. These scores were tested for association with the DMRT3 genotypes. Although AA horses were more successful as racehorses, the CC and CA horses appear more adapted for classical riding disciplines. The AA horses received significantly lower gait scores compared with C-horses for the majority of gaits. Except for rhythm in extended canter (P = 0.05), there were no significant differences between CA and CC horses. This study shows that there are different optimal genotypes for different disciplines and the DMRT3 mutation clearly influences gaits and performance in Finnhorses.
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| 3. |
- Jäderkvist Fegraeus, Kim, et al.
(författare)
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The importance of the DMRT3 'Gait keeper' mutation on riding traits and gaits in Standardbred and Icelandic horses
- 2015
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Ingår i: Livestock Science. - : Elsevier BV. - 1871-1413 .- 1878-0490. ; 176, s. 33-39
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have shown that a single base-pair mutation, a change from cytosine (C) to adenine (A), in the DMRT3 gene affects both the ability to show ambling and lateral gaits in a wide range of horse breeds, as well as racing performance and trotting technique in Standardbred and Nordic trotters. The variant allele is present in gaited breeds but is absent, or found at a very low frequency, in breeds used for Western-European style riding and flat racing, like the Swedish Warmblood and Thoroughbreds as well as in draught horses. This indicates that the variant allele might have a negative effect on certain riding performance traits in horses. Therefore, one aim of this study was to investigate whether the DMRT3 variant affects canter in Standardbred trotters, and to test if heterozygous horses (CA) were better suited for Western-European style riding than homozygous horses (M). Riding traits were studied in 115 Standardbred horses, and a similar study was also performed with data from 55 Nordic trotters. The results showed that CA Standardbreds had significantly better balance in canter, both collected and extended canter, than M horses. The CA horses also got significantly higher scores for transitions in collected canter. For the rhythm we found no significant differences between the genotypes. In the Nordic trotters we were unable to establish any significant difference for canter ability. Another aim of this study was to investigate the effect of the variant allele on riding abilities and gaits in the Icelandic horse (n=446). Practically all horse breeds considered to be three-gaited have a CC genotype, in contrast Icelandic CC horses can show tolt We therefore tested whether the variant influenced how difficult it was to initiate tolt training for these horses. It was also investigated whether the variant affects which gaits Icelandic horses choose, both at liberty and during initial training. Icelandic CC horses were significantly more difficult to train to tolt compared to CA and AA horses. The M Icelandic horses showed the lateral gaits tolt and pace significantly more frequent, both at liberty and during initial training, than CA or CC horses. The majority of the Icelandic CC and CA horses chose trot at liberty and during initial training.
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