Project description:Most animals restrict their activity to specific part of the day, being either diurnal, nocturnal, or crepuscular. The genetic basis underlying this diurnal preference is largely unknown. Under laboratory conditions, Drosophila melanogaster is crepuscular, showing a bi-modal activity profile. However, recent experiments in our lab indicated that high variability among individuals exist, particularly in strains that derive from different wild populations. By assembling together flies from various geographical strains, we have generated a highly diverse population whose progeny exhibited extreme diurnal preference, including diurnal and nocturnal flies. We have used this population as a starting point for an artificial selection experiment in which we selected males that show the most extreme diurnal preference and mated them to their sisters. The response to selection was strong, and already after 10 selection cycles we obtained highly diurnal (D) and nocturnal (N) strains. Another strain that was not selected and showed intermediate behaviour (crepuscular) served as a control (C). These strains provide us with a unique opportunity to understand the genetics of diurnal preference.
Project description:Understanding how DNA sequence variation is translated into variation for complex phenotypes has remained elusive, but is essential for predicting adaptive evolution, selecting agriculturally important animals and crops, and personalized medicine. Here, we quantified genome-wide genetic variation in gene expression in the sequenced inbred lines of the Drosophila melanogaster Genetic Reference Panel. We found that a substantial fraction of the Drosophila transcriptome is genetically variable and organized into modules of genetically correlated transcripts, which provide functional context for newly identified novel transcribed regions. We identified regulatory variants for the mean and variance of gene expression, both of which showed oligogenic genetic architecture. Expression quantitative trait loci the mean, but not the variance, of gene expression were concentrated near genes. This comprehensive characterization of transcriptomic diversity and its genetic basis in the DGRP is critically important for a systems understanding of quantitative trait variation.
Project description:MicroRNAs are a class of small (~22nt) endogenous RNAs that regulate target transcript expression post-transcriptionally. Previous studies characterized age-related changes in diurnal transcript expression but it is not understood how these changes are regulated, and whether they may be attributed in part to changes in microRNA expression or activity with age. Diurnal small RNA expression changes with age were not previously studied. To interrogate changes in small RNA expression with age, we collected young (5 day) and old (55 day) Drosophila melanogaster around-the-clock and performed deep sequencing on size-selected RNA from whole heads. We find several microRNAs with changes in rhythmicity after aging, and we investigate microRNAs which are differentially expressed with age. We find that predicted targets of differentially expressed microRNAs have RNA-binding and transcription factor activity. We use a previously published method to identify mRNA transcripts which show evidence of microRNA targeting that is altered after aging, and find several that are involved in muscle development and maintenance. Finally, we identify novel microRNAs using the random-forest-based method miRWoods, which surprisingly also discovered transfer RNA-derived fragments.
Project description:This project uses pooled poly A (+) RNA from the DGRP to derive transcript models specific to DGRP. The derived transcript models provide the basis for quantifying gene expression in the DGRP lines using genome tiling arrays.
Project description:Resistance to oxidative stress plays a vital role in animal physiology, where it influences both life history traits and the ability to tolerate the effects of a myriad of environmental stressors. While stress resistance has previously been shown to share a role in shaping an organism's response to traits as varied as desiccation, thermal tolerance and xenobiotic resistance, heavy metal tolerance presents a particular challenge with regards to adaptation to stress. Heavy metals contamination can result in robust and persistent selection pressure: not only is acute exposure highly toxic, but metals can accumulate in the environment over long periods, prolonging this exposure. However, many heavy metals, such as copper and zinc, are also essential micronutrients, which may constrain adaption in high copper conditions. To determine the genetic basis of copper tolerance in European Drosophila melanogaster, we phenotyped 76 inbred lines sampled from nine locations across Western Europe on copper sulphate, demonstrating that that copper tolerance is a highly variable trait. A combination of long-read nanopore sequencing and high-throughput RNA-seq analysis carried out before and after copper exposure shows that while copper tolerance is a highly heterogenous trait, affected by changes in expression across multiple loci, the greatest changes in expression a seen in the digestive tract. In addition, a large proportion of genes found differentially expressed upon copper exposure have previously shown to be regulated by a number of transcription factors with known roles in a broad range of metabolic processes, indicating that while the initial response may be tissue restricted, long term affects of copper expose are more likely to be systemic.
Project description:We performed genome-wide expression assays comparing gene expression in the Drosophila melanogaster third larval instar genital imaginal disc between males and females. We used microarrays to compare the relative expression levels of five independent male versus female comparisons for each of two different D. melanogaster wild-type strains, Canton-S and Berlin.