Analysis of the brain transcriptome in lines of laying hens divergently selected for feather pecking

Abstract

Background: Feather pecking (FP) in laying hens reduces animal welfare and leads to economic losses for the layer industry. FP is considered a heritable condition that is influenced by dysregulation of neurotransmitter homeostasis, the gut microbiome, and the immune system. To identify genes and biological pathways responsible for FP behavior we compared the brain transcriptomes of 48 hens divergently selected for FP. In addition, we tested if high feather peckers (HFP) and low feather peckers (LFP) respond differently to light since light has been shown to trigger FP behavior. Results: Of approximately 48 million reads/sample an average of 98.4% were mapped to the chicken genome (GRCg6a). We found 13,070 expressed genes in the analyzed brains of which 423 showed differential expression between HFP and LFP. Genes of uncertain function and non-coding RNAs were overrepresented among those transcripts. Functional analyses revealed the involvement of cholinergic signaling, postsynaptic activity, membrane channels, and the immune system. After the light stimulus, 28 genes were found to be differentially expressed. These included an interaction cluster of core components of the circadian clock. However, differences in the response to light between HFP and LFP were not detectable. Conclusions: Genes involved in cholinergic signaling, channel activity, synaptic transmission, and immune response were found to be involved in FP behavior. We propose a model in which the gut microbiota modulates the immune system, which in turn affects cholinergic signaling. This might have an influence on monoamine signaling with possible involvement of GABA or glutamate signaling.

Meta-analyses of genome wide association studies in lines of laying hens divergently selected for feather pecking using imputed sequence level genotypes

“…Furthermore, the genes ZEB2 and MRPL13, which are affected by significantly associated variants, respond to nicotine treatment [25,30]. This goes in line with our previous results where we detected differential expression of major receptors for nicotine between HFP and LFP hens [32]. Based on our findings from gene cluster analysis and protein interaction clustering we also propose an involvement of phosphatidylinositol signaling, disturbances of the Golgi apparatus, and structural abnormalities in the brain as possible factors that influence the predisposition for FP behavior.…”

“…Another gene affected by a significantly associated down-stream gene variant is MRPL13 (2_136,907,571, pvalue = 2.480 × 10 − 9 ), which was found to be upregulated after nicotine treatment [30] like the already mentioned ZEB2 gene. We found genes encoding subunits of nicotinic acetylcholine receptors (nAchR), the major receptors for nicotine [31], to be differentially expressed in the brain transcriptome of hens divergently selected for feather pecking [32]. Both findings taken together present strong evidence for the involvement of nAchR in the propensity to FP behavior (already discussed in [32]).…”

“…We found genes encoding subunits of nicotinic acetylcholine receptors (nAchR), the major receptors for nicotine [31], to be differentially expressed in the brain transcriptome of hens divergently selected for feather pecking [32]. Both findings taken together present strong evidence for the involvement of nAchR in the propensity to FP behavior (already discussed in [32]). Gene cluster analysis with clusterProfiler revealed that genes belonging to the KEGG category "Phosphatidylinositol signaling system" are enriched among genes associated with the trait FPD (Table 4).…”

Multi-species transcriptome meta-analysis of the response to retinoic acid in vertebrates and comparative analysis of the effects of retinol and retinoic acid on gene expression in LMH cells

“…Procedures have already been described in a previous study [ 70 ]. Briefly: Total RNA input quality was evaluated on a TapeStation 4200 (Agilent, USA), and all samples showed a RIN score > 8.…”

Edible Environmental Enrichments in Littered Housing Systems: Do Their Effects on Integument Condition Differ Between Commercial Laying Hen Strains?

“…With our study, these interactions were extended for an EM supply regarding plumage damage and skin injuries. Differences in the expression of genes relevant for feather pecking could be potential causes of this [ 72 ]. Furthermore, the divergent effect in the corticosterone reaction patterns between different laying hen strains after an additional intake of fibrous substrates could also offer an explanation [ 73 ].…”