P-element-induced variation in metabolic regulation in Drosophila.
Movement of transposable elements have demonstrated to be a cause of genetic variation that is relevant to quantitative characters in Drosophila. Here a particular class of P-element-induced variation known to be mediated through changes in expression of targeted enzyme-encoding genes is examined. Balancer chromosome and 139 third-chromosome lines of Drosophila melanogaster bearing unique stable P-element insertions in a common genetic background. Lines that were homozygous for second-chromosome P-element insertions were significantly more heterogeneous than control lines in 10 of 16 characters, whereas third-chromosome insertion lines were heterogeneous in 11 of the 16 traits. The average mutational variance per insertion relative to environmental variance (Vm/Ve) was 5.7 x 10(-2), and estimates varied widely across characters. The distributions of mutational effects tended to be skewed, with a longer tail toward high enzyme activities. Mutational effects deviated from a normal distribution in 15 of the 16 traits and significant outlier lines were found in both a positive and negative direction in several characters. Pleiotropic effects of single P-element insertions were quantified by correlation, and, after correcting for simultaneous tests, of the 91 correlations, 37 were significant at the 5% level. The pattern of pleiotropic effects derviated both from the equilibrium genetic correlations quantified in a previous study and from the correlations of mutational effects in a mutation-accumulation experiment, suggesting that multiple forces are at play that shape extant variation.
Clark
A G
AG
Department of Biology, Pennsylvania State University, University Park 16802.
Wang
L
L
Hulleberg
T
T
D000220:Adaptation, Biological / Q000235:genetics; D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D004251:DNA Transposable Elements / Q000235:genetics*; D004331:Drosophila melanogaster / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D004798:Enzymes / Q000032:analysis; D005260:Female; D014644:Genetic Variation; D008297:Male; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000235:genetics*
D004251:DNA Transposable Elements; D004798:Enzymes