View Program - 63rd Annual Drosophila Research Conference

Genetic characterization of stress response often relies on the assessment of a single trait; however, single trait assessments do not fully encompass an individual’s response to stressors. We took a multi-trait approach to characterize the genetic factors that contribute to variation in resistance to copper toxicity by examining adult, developmental, and behavioral responses to copper stress. Copper is one of several common heavy metal pollutants that are leached into the environment through mining and agriculture practices. Copper is an especially interesting metal because it is required for normal physiological function and development at low concentrations, but at toxic levels copper exposure can lead to organ damage and failure as well as impairment of neurological function. Furthermore, our previous work has demonstrated that genes and pathways involved in detoxification of non-biologically necessary heavy metals (lead and cadmium) also contribute to variation in the response to copper toxicity. Using the approximately 1500 genetically stable strains that make up the Drosophila Synthetic Population Resource (DSPR), we previously identified 13 regions of the genome that contribute to adult physiological resistance to copper using quantitative trait locus (QTL) mapping. We are currently measuring developmental viability under copper stress in the DSPR, and preliminary QTL analysis indicates that the genetic control of adult and developmental copper resistance may be partially life stage specific despite the lack of a significant phenotypic correlation between the traits. Thus far, only one QTL is shared between the adult and developmental response to copper stress. The shared QTL highlights mekk1 as a potential candidate gene, and estimated DSPR founder haplotype effects on developmental and adult responses to copper at this QTL suggests that allelic variation for mekk1 in the DSPR may have similar effects on copper resistance in both life stages. In addition to multiple physiological traits, we measured variation in copper detection ability in 200 DSPR strains and found that the ability to detect copper at low concentrations in food is genetically variable. We also found that copper-tainted food consumption is negatively correlated with adult physiological resistance to copper stress, underscoring the importance of combining physiological and behavioral assessments of stress response. By measuring multiple traits related to copper stress in the same large panel of genetically stable strains, we will ultimately be able to reveal the genomic independence and interactions underlying multiple traits that shape the organismal response to chemical stress.

Multi-trait genetic characterization of resistance to heavy metal stress