Eli Grindflek of NORSVIN and co-authors from the Norwegian University of Life Sciences and Sequenom Inc have published a paper in BMC Genetics on their work to study the genes regulating the level of androstenone in male pigs.

The researchers explain that boar taint is an unpleasant odour and flavour of the meat and occurs in a high proportion of uncastrated male pigs. Androstenone, a steroid produced in testis and acting as a sex pheromone regulating reproductive function in female pigs, is one of the main compounds responsible for boar taint. The primary goal of the present investigation was to determine the differential gene expression of selected candidate genes related to levels of androstenone in pigs.

Results

Altogether, 2,560 boars from the Norwegian Landrace and Duroc populations were included in this study.

Testicle samples from the 192 boars with most extreme high or low levels of androstenone in fat were used for RNA extraction, and 15 candidate genes were selected and analysed by real-competitive PCR analysis.

The genes cytochrome P450 c17 (CYP17A1), steroidogenic acute regulatory protein (STAR), aldo-keto reductase family 1 member C4 (AKR1C4), short-chain dehydrogenase/reductase family member 4 (DHRS4), ferritin light polypeptide (FTL), sulfotransferase family 2A, dehydroepiandrosterone-preferring member 1 (SULT2A1), cytochrome P450 subfamily XIA polypeptide 1 (CYP11A1), cytochrome b5 (CYB5A), and 17-beta-hydroxysteroid dehydrogenase IV (HSD17B4) were all found to be significantly (P<0.05) up-regulated in high androstenone boars in both Duroc and Landrace.

Furthermore, cytochrome P450 c19A2 (CYP19A2) was down-regulated and progesterone receptor membrane component 1 (PGRMC1) was up-regulated in high-androstenone Duroc boars only, while CYP21 was significantly down-regulated in high-androstenone Landrace only.

The genes nuclear receptor co-activator 4 (NCOA4), sphingomyrlin phosphodiesterase 1 (SMPD1) and 3-beta-hydroxysteroid dehydrogenase (HSD3B) were not significantly differentially expressed in either breed.

Additionally, association studies were performed for the genes with one or more detected SNPs. Association between SNP and androstenone level was observed in CYB5A only, suggesting cis-regulation of the differential transcription in this gene.

Conclusion

A large pool of pig material of highly extreme androstenone levels was investigated.

Grindflek and co-authors say that the current study contributes to the knowledge about which genes that is differentially expressed regard to the levels of androstenone in pigs.

They conclude that results in this paper suggest that several genes are important in the regulation of androstenone level in boars and warrant further evaluation of the above-mentioned candidate genes, including analyses in different breeds, identification of causal mutations and possible gene interactions.

Reference

Grindflek E., I. Berget, M. Moe, P. Oeth and S. Lien. 2010. Transcript profiling of candidate genes in testis of pigs exhibiting large differences in androstenone levels. BMC Genetics 2010, 11:4 doi:10.1186/1471-2156-11-4

Further Reading

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You can view a provisional verson of the full paper by clicking here.