Brain gene expression in relation to fearfulness in female red junglefowl (Gallus gallus)

• The biology of fear is central to animal welfare and hasbeen a major target for selection during domestication.Fear responses were studied in female red junglefowl(RJF), the ancestor of domesticated chickens. A totalof 31 females were tested in a ground predator test,an aerial predator test and a tonic immobility (TI)test, in order to assess their level of fearfulnessacross different situations. Two to six variables fromeach test were entered into a principal component(PC) analysis, which showed one major fearfulnesscomponent (explaining 27% of the variance). Based onthe PC scores, four high- and four low-fearful birds werethen selected for gene expression analysis. From eachof these birds, the midbrain region (including thalamus,hypothalamus, pituitary, mesencephalon, pons, nucleustractus solitarii and medulla oblongata), was collectedand global gene expression compared between groupsusing a 14k chicken cDNA microarray. There were 13significantly differentially expressed (DE) genes (basedonM > 1 andB > 0; FDR-adjusted P < 0.05) between thefearful and non-fearful females. Among the DE genes,we identified the neuroprotein Axin1, two potentialDNA/RNA regulating proteins and a retrotransposontranscript situated in a well-studied quantitative traitloci (QTL) region on chromosome 1, known to affectseveral domestication-related traits. The differentiallyexpressed genes may be part of a possible molecularmechanism controlling fear responses in fowl.

Nyckelord

Chicken

domestication

fear

gene expression

microarray

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