Sequence comparison of prefrontal cortical brain transcriptome from a tame and an aggressive silver fox (Vulpes vulpes)

<p>Abstract</p> <p>Background</p> <p>Two strains of the silver fox (<it>Vulpes vulpes</it>), with markedly different behavioral phenotypes, have been developed by long-term selection for behavior. Foxes from the tame strain exhibit friendly behavior towards humans, paralleling the sociability of canine puppies, whereas foxes from the aggressive strain are defensive and exhibit aggression to humans. To understand the genetic differences underlying these behavioral phenotypes fox-specific genomic resources are needed.</p> <p>Results</p> <p>cDNA from mRNA from pre-frontal cortex of a tame and an aggressive fox was sequenced using the Roche 454 FLX Titanium platform (> 2.5 million reads & 0.9 Gbase of tame fox sequence; >3.3 million reads & 1.2 Gbase of aggressive fox sequence). Over 80% of the fox reads were assembled into contigs. Mapping fox reads against the fox transcriptome assembly and the dog genome identified over 30,000 high confidence fox-specific SNPs. Fox transcripts for approximately 14,000 genes were identified using SwissProt and the dog RefSeq databases. An at least 2-fold expression difference between the two samples (p < 0.05) was observed for 335 genes, fewer than 3% of the total number of genes identified in the fox transcriptome.</p> <p>Conclusions</p> <p>Transcriptome sequencing significantly expanded genomic resources available for the fox, a species without a sequenced genome. In a very cost efficient manner this yielded a large number of fox-specific SNP markers for genetic studies and provided significant insights into the gene expression profile of the fox pre-frontal cortex; expression differences between the two fox samples; and a catalogue of potentially important gene-specific sequence variants. This result demonstrates the utility of this approach for developing genomic resources in species with limited genomic information.</p

Data from: On the origin of a domesticated species: identifying the parent population of Russian silver foxes (Vulpes vulpes)

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Anterior Pituitary Transcriptome Suggests Differences in ACTH Release in Tame and Aggressive Foxes

Domesticated species exhibit a suite of behavioral, endocrinological, and morphological changes referred to as “domestication syndrome.” These changes may include a reduction in reactivity of the hypothalamic-pituitary-adrenal (HPA) axis and specifically reduced adrenocorticotropic hormone release from the anterior pituitary. To investigate the biological mechanisms targeted during domestication, we investigated gene expression in the pituitaries of experimentally domesticated foxes (Vulpes vulpes). RNA was sequenced from the anterior pituitary of six foxes selectively bred for tameness (“tame foxes”) and six foxes selectively bred for aggression (“aggressive foxes”). Expression, splicing, and network differences identified between the two lines indicated the importance of genes related to regulation of exocytosis, specifically mediated by cAMP, organization of pseudopodia, and cell motility. These findings provide new insights into biological mechanisms that may have been targeted when these lines of foxes were selected for behavior and suggest new directions for research into HPA axis regulation and the biological underpinnings of domestication

Silver_fox_dataset_DRYAD

mtDNA sequences for 3 breeding lines of russian silver foxe

Genes located inside or within 50,000 bp from start and end of the multi SNP clusters in the dog genome.

<p>Cluster numbers refer to the numbering from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0127013#pone.0127013.t002" target="_blank">Table 2</a>.</p><p>Genes located inside or within 50,000 bp from start and end of the multi SNP clusters in the dog genome.</p

SNP minor allele frequency and heterozygosity in tame and aggressive populations.

<p>SNP minor allele frequency and heterozygosity in tame and aggressive populations.</p

Estimation of population structure using STRUCTURE.

<p>Cluster analysis of fox genotypes was performed at four values of K (2, 3, 4, and 5) without population information. The numbers of assumed clusters are indicated on the y-axis. The population origin of individuals is indicated on x-axis. On each graph the individuals are listed in the order obtained at K = 3. Each individual is represented by a bar that is segmented into colors based on the assignment into inferred clusters given the assumption of K populations. The length of the colored segment is the estimated proportion of the individual’s genome belonging to that cluster. The analysis was run in 8 replicates for each K, the replicate with the highest likelihood is shown. The genetic structure analysis clearly differentiated the tame population from the aggressive one and did not reveal significant population stratification within the tame population at every K tested. In contrast, the population stratification within the aggressive population became apparent at K = 3.</p