Abstract
BackgroundThe genetic and molecular mechanisms of tameness are largely unknown. A line of silver foxes (Vulpes vulpes) selected for non-aggressive behavior has been used in Russia since the 1960's to study the effect of domestication. We have previously compared descendants of these selected (S) animals with a group of non-selected (NS) silver foxes kept under identical conditions, and showed that changes in the brain transcriptome between the two groups are small. Unexpectedly, many of the genes showing evidence of differential expression between groups were related to hemoproteins.ResultsIn this study, we use quantitative RT-PCR to demonstrate that the activity of heme related genes differ between S and NS foxes in three regions of the brain. Furthermore, our analyses also indicate that changes in mRNA levels of heme related genes can be well described by an additive polygenic effect. We also show that the difference in genetic background between the two lines of foxes is limited, as estimated by mitochondrial DNA divergence.ConclusionOur results indicate that selection for tameness can modify the expression of heme related genes in canid brain regions known to modulate emotions and behavior. The possible involvement of heme related genes in behavior is surprising. It is possible that hemoglobin modulates the behavior of canids by interaction with CO and NO signaling. Another possibility is that hemorphins, known to be produced after enzymatic cleavage of hemoglobin, are responsible for behavioral alterations. Thus, we hypothesize that hemoglobin metabolism can be a functionally relevant aspect of the domestic phenotype in foxes selected for tameness.
Highlights
The genetic and molecular mechanisms of tameness are largely unknown
We have previously shown that the brain gene expression profile of domestic dogs has diverged from that observed in their wild ancestor the gray wolf, suggesting that behavioral selection during domestication has modified mRNA expression levels of genes with multiple functions [4]
The comparison of the mitochondrial DNA (mtDNA) sequences were made for a total of 29 NS, 23 S, 23 Cross, 12 wild foxes and an additional 26 wild foxes retrieved from databases
Summary
The genetic and molecular mechanisms of tameness are largely unknown. A line of silver foxes (Vulpes vulpes) selected for non-aggressive behavior has been used in Russia since the 1960's to study the effect of domestication. In the 1960s D.K. Belyaev, the late director of the Institute of Cytology and Genetics in Novosibirsk, initiated a domestication experiment on farmed silver foxes, a color morph of the red fox (Vulpes vulpes), to test the hypothesis that physiological and morphological changes in the domestic dog could have resulted from selection for tameness alone [5]. The late director of the Institute of Cytology and Genetics in Novosibirsk, initiated a domestication experiment on farmed silver foxes, a color morph of the red fox (Vulpes vulpes), to test the hypothesis that physiological and morphological changes in the domestic dog could have resulted from selection for tameness alone [5] In this experiment, that still continues, farmed foxes have been selected for non-aggressive behavior towards man for more than 40 generations. Developmental, morphological and neurochemical changes (including modulations of the serotonergic system and the activity of the hypothalamuspituitary-adrenal (HPA) axis) are associated with the behavioral changes in the selected foxes [7,8,9,10]
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