Abstract
BackgroundLong-term selection (> 45 generations) for low or high juvenile body weight from a common founder population of White Plymouth Rock chickens has generated two extremely divergent lines, the LWS and HWS lines. In addition to a > 9-fold difference between lines for the selected trait, large behavioural and metabolic differences between the two lines evolved during the course of the selection. We recently compared gene expression in brain tissue from birds representing these lines using a global cDNA array analysis and the results showed multiple but small expression differences in protein coding genes. The main differentially expressed transcripts were endogenous retroviral sequences identified as avian leucosis virus subgroup-E (ALVE).ResultsIn this work we confirm the differential ALVE expression and analysed expression and number of proviral integrations in the two parental lines as well as in F9 individuals from an advanced intercross of the lines. Correlation analysis between expression, proviral integrations and body weight showed that high ALVE levels in the LWS line were inherited and that more ALVE integrations were detected in LWS than HWS birds.ConclusionWe conclude that only a few of the integrations contribute to the high expression levels seen in the LWS line and that high ALVE expression was significantly correlated with lower body weights for the females but not males. The conserved correlation between high expression and low body weight in females after 9 generations of intercrosses, indicated that ALVE loci conferring high expression directly affects growth or are very closely linked to loci regulating growth.
Highlights
Long-term selection (> 45 generations) for low or high juvenile body weight from a common founder population of White Plymouth Rock chickens has generated two extremely divergent lines, the LWS and high weight selection (HWS) lines
The results show that high avian leucosis virus subgroup-E (ALVE) expression among F9 birds was significantly correlated with low body weight for the females but not for males
Animals and tissues Lines LWS and HWS were developed from a common founder population of crosses among seven inbred lines of White Plymouth Rocks, a breed used for egg production and broiler breeding
Summary
Long-term selection (> 45 generations) for low or high juvenile body weight from a common founder population of White Plymouth Rock chickens has generated two extremely divergent lines, the LWS and HWS lines. We recently compared gene expression in brain tissue from birds representing these lines using a global cDNA array analysis and the results showed multiple but small expression differences in protein coding genes. Selection during more than 45 generations for low or high body weight from a common founder population of crosses among seven lines of White Plymouth Rock chickens has generated two extremely divergent lines; the low (LWS) and high weight selection (HWS) lines. We recently compared gene expression in brain tissue using a global cDNA array analysis with the purpose to reveal over-all expression differences between the HWS and LWS lines that may be causally related to their extremely different phenotypes. Genes that regulate neuronal development and plasticity such as regulators of actin filament polymerization and genes involved in lipid metabolism were over-represented among differentially expressed genes [7]
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