title: Adrenal cortex expression quantitative trait loci in a German Holstein × Charolais cross.
abstract: BACKGROUND
  The importance of the adrenal gland in regard to lactation and reproduction in cattle has been recognized early. Caused by interest in animal welfare and the impact of stress on economically important traits in farm animals the adrenal gland and its function within the stress response is of increasing interest. However, the molecular mechanisms and pathways involved in stress-related effects on economically important traits in farm animals are not fully understood. Gene expression is an important mechanism underlying complex traits, and genetic variants affecting the transcript abundance are thought to influence the manifestation of an expressed phenotype. We therefore investigated the genetic background of adrenocortical gene expression by applying an adaptive linear rank test to identify genome-wide expression quantitative trait loci (eQTL) for adrenal cortex transcripts in cattle.
  
  
  RESULTS
  A total of 10,986 adrenal cortex transcripts and 37,204 single nucleotide polymorphisms (SNPs) were analysed in 145 F2 cows of a Charolais × German Holstein cross. We identified 505 SNPs that were associated with the abundance of 129 transcripts, comprising 482 cis effects and 17 trans effects. These SNPs were located on all chromosomes but X, 16, 24 and 28. Associated genes are mainly involved in molecular and cellular functions comprising free radical scavenging, cellular compromise, cell morphology and lipid metabolism, including genes such as CYP27A1 and LHCGR that have been shown to affect economically important traits in cattle.
  
  
  CONCLUSIONS
  In this study we showed that adrenocortical eQTL affect the expression of genes known to contribute to the phenotypic manifestation in cattle. Furthermore, some of the identified genes and related molecular pathways were previously shown to contribute to the phenotypic variation of behaviour, temperament and growth at the onset of puberty in the same population investigated here. We conclude that eQTL analysis appears to be a useful approach providing insight into the molecular and genetic background of complex traits in cattle and will help to understand molecular networks involved.
authors.affiliation: Institute for Genome Biology, Leibniz Institute for Farm Animal Biology, Wilhelm-Stahl-Allee, Dummerstorf, Germany.|Current affiliation: Institute for Farm Animal Research and Technology, University of Rostock, Justus-von-Liebig-Weg, 18059, Rostock, Germany.
authors.forename: Bodo
authors.initials: B
authors.lastname: Brand
authors.affiliation: Institute of Medical Biometry and Statistics, University of Lübeck, Ratzeburger Allee, Lübeck, Germany.
authors.forename: Markus O
authors.initials: MO
authors.lastname: Scheinhardt
authors.affiliation: Institute for Farm Animal Research and Technology, University of Rostock, Justus-von-Liebig-Weg, Rostock, Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Friedrich
authors.affiliation: Institute for Farm Animal Research and Technology, University of Rostock, Justus-von-Liebig-Weg, Rostock, Germany.
authors.forename: Daisy
authors.initials: D
authors.lastname: Zimmer
authors.affiliation: Institute for Genetics and Biometry, Leibniz Institute for Farm Animal Biology, Wilhelm-Stahl-Allee, Dummerstorf, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Reinsch
authors.affiliation: Institute for Genome Biology, Leibniz Institute for Farm Animal Biology, Wilhelm-Stahl-Allee, Dummerstorf, Germany.
authors.forename: Siriluck
authors.initials: S
authors.lastname: Ponsuksili
authors.affiliation: Institute for Genome Biology, Leibniz Institute for Farm Animal Biology, Wilhelm-Stahl-Allee, Dummerstorf, Germany.|Institute for Farm Animal Research and Technology, University of Rostock, Justus-von-Liebig-Weg, Rostock, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Schwerin
authors.affiliation: Institute of Medical Biometry and Statistics, University of Lübeck, Ratzeburger Allee, Lübeck, Germany. ziegler@imbs.uni-luebeck.de.|Center for Clinical Trials, University of Lübeck, Ratzeburger Allee, Lübeck, Germany. ziegler@imbs.uni-luebeck.de.|School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Pietermaritzburg, South Africa. ziegler@imbs.uni-luebeck.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ziegler
keywords: Adrenal cortex; Cow; Gene expression; Pathway analysis; eQTL analysis