Transvection-based gene regulation in Drosophila is a complex and plastic trait.
Bottom Line: We further show that the magnitude of transvection at the Men locus is modified by both genetic background and environment (temperature), demonstrating that transvection is a plastic phenotype.Our results suggest that transvection effects in D. melanogaster are shaped by a dynamic interplay between environment and genetic background.Interestingly, we find that cis-based regulation of the Men gene is more robust to genetic background and environment than trans-based.
Affiliation: Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON, P3E 2C6, Canada.Show MeSH
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Mentions: The D. melanogaster Malic enzyme (Men) gene is developing into a promising system for determination of the molecular mechanisms underlying trans-interactions. Flies heterozygous for small deletion knockout alleles of the Malic enzyme gene (Men) have greater than expected levels of malic enzyme (MEN) protein activity that are not simply physiological up-regulation (Merritt et al. 2005; 2009; Lum and Merritt 2011; Figure 1). Lum and Merritt (2011) used a suite of knockout alleles (MenExi−) with small deletions around the Men transcription start site (Figure 1, B and C) and a set of Men+ third chromosomes extracted from wild populations to demonstrate that the high levels of MEN activity were driven by trans-interaction−dependent up-regulation, and that the amount of increased MEN activity varied with the size and location of the excisions and the genetic background of the fly. The authors suggested that the up-regulation resulted from transvection (Figure 1, D and E). Although the Men regulatory region has not been well characterized, Lum and Merritt (2011) identified a suite of potential regulatory sites in the region computationally and suggested that the experimental differences in trans-effects of alleles with even small differences in their excision may be a function of multiple interacting regulatory sites. Interestingly, the differences in trans-effects caused by different deletion alleles and third chromosomes backgrounds often were subtle, and the significant variations were only detectable because of the sensitivity of the MEN activity assay; activity differences as small as 5% can be reliably distinguished (Merritt et al. 2005, 2009; Lum and Merritt 2011; Rzezniczak and Merritt 2012).
Affiliation: Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON, P3E 2C6, Canada.