title: Gene expression during testis development in Duroc boars.
abstract: Androstenone is a steroid pheromone occurring in the pubertal Leydig cells. Breeding against androstenone can decrease pheromone odour in swine meat but appears to cause unwanted side effects such as delayed onset of puberty. To study causality, global gene expression in developing boar testes at 12, 16, 20 and 27 weeks was investigated using a porcine cDNA microarray. The morphological status and androgenic levels of the same individuals have been described in a previous publication. In the present paper, expression of genes and pathways has been analysed with reference to these findings. Nine clusters of genes with significant differential expression over time and 49 functional charts were found in the analysed testis samples. Prominent pathways in the prepubertal testis were associated with tissue renewal, cell respiration and increased endocytocis. E-cadherines may be associated with the onset of pubertal development. With elevated steroidogenesis (weeks 16 to 27), there was an increase in the expression of genes in the MAPK pathway, STAR and its analogue STARD6. A pubertal shift in genes coding for cellular cholesterol transport was observed. Increased expression of meiotic pathways coincided with the morphological onset of puberty. Puberty-related change in Ca(2+) pathway transcripts, neurosteroids, neuronal changes and signalling in redox pathways suggested a developmental-specific period of neuromorphogenesis. Several growth factors were found to increase differentially over time as the testis matured. There may be interactions between MAPK, STAR and growth factors during specific periods. In conclusion, pathways for neurogenesis, morphological pathways and several transcripts for growth factors, which have known modulating effects on steroidogenesis and gonadotropins in humans and rodents, act at specific ages and developmental stages in the boar testis. The age dependency and complexity shown for development-specific testis transcripts must be considered when selecting phenotypic parameters for genetic selection for low androstenone. The results of selection based on measurement of phenotypic maturation and androstenone (or other steroid) levels at one specific age may differ depending on the age used. More research is necessary to find the optimal phenotype to use in order to reduce the unwanted side effects.
authors.affiliation: 1Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine and Biosciences,Norwegian University of Life Sciences (NMBU),Ullevålsveien 72,Pb 8146 Dep,N-0033 Oslo,Norway.
authors.forename: S
authors.initials: S
authors.lastname: Lervik
authors.affiliation: 2National Veterinary Institute,Section for Epidemiology,Ullevålsveien 68,Pb 750 Sentrum,N-0106 Oslo,Norway.
authors.forename: A B
authors.initials: AB
authors.lastname: Kristoffersen
authors.affiliation: 3Faculty of Agricultural Sciences,University of Aarhus,Blichers Alle 20,Pb 50,DK-8830 Tjele,Denmark.
authors.forename: L N
authors.initials: LN
authors.lastname: Conley
authors.affiliation: 1Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine and Biosciences,Norwegian University of Life Sciences (NMBU),Ullevålsveien 72,Pb 8146 Dep,N-0033 Oslo,Norway.
authors.forename: I C
authors.initials: IC
authors.lastname: Oskam
authors.affiliation: 3Faculty of Agricultural Sciences,University of Aarhus,Blichers Alle 20,Pb 50,DK-8830 Tjele,Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Hedegaard
authors.affiliation: 1Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine and Biosciences,Norwegian University of Life Sciences (NMBU),Ullevålsveien 72,Pb 8146 Dep,N-0033 Oslo,Norway.
authors.forename: E
authors.initials: E
authors.lastname: Ropstad
authors.affiliation: 4NMBU, Faculty of Veterinary Medicine and Biosciences,Department of Basic Sciences and Aquatic Medicine,Ullevålsveien 72,Pb 8146 Dep,N-0033 Oslo,Norway.
authors.forename: I
authors.initials: I
authors.lastname: Olsaker
mesh_terms: D000736:Androstenes / Q000378:metabolism*; D000818:Animals; D001947:Breeding; D018507:Gene Expression Regulation, Developmental; D008297:Male; D005810:Multigene Family; D020411:Oligonucleotide Array Sequence Analysis / Q000662:veterinary; D013552:Swine / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D013737:Testis / Q000254:growth & development*
chemical_list: D000736:Androstenes; C000214:androst-16-en-3-one
keywords: boar testis; gene expression; pathway analysis; pubertal; testis development