Folic acid-enriched diet genotype and sex-dependent effects on Drosophila melanogaster imago life expectancy: chronic experiment

Introduction. The negative effects of excessive folic acid consumption by insects are widely known, like gut microbiota disruptions, reactive oxygen species accumulation, and aberrant DNA methylation. These can either directly lead to an individual's death due to metabolic changes, or affect further generations through the aberrant gamete production of exposed individuals. At the same time, there is a high demand for folates during the larval stage, including for proper DNA synthesis and DNA and histone methylation. This study represents the analysis of folic acid supplementation effects at 1 mg/ml concentration on the imago life expectancy of two Drosophila melanogaster stocks (radius incompletus and Canton-Special).

Methods. To determine if adaptation to folic acid excess in a larval culture medium takes place or not, we performed a chronic experiment in a sixth generation of flies. Additionally, to determine the sex-specific parental influence on the offspring's survival, two groups were added to the analysis, in which either the mother or father came from a group that consumed additional folic acid at the larval stage. The survival curve analysis was conducted using Aalen’s additive model from the survival package in R.

Results. When chronically consuming excess folic acid (1 mg/ml), drosophila imago life expectancy varies depending on the genotype (belonging to a particular stock) and sex of the individual. The directionality of the detected effects does not depend on which parent (mother, father, or both) was exposed, but depends on the sex of the offspring under analysis. We note the negative impact of excess folic acid intake by parents at the larval stage on their offspring's life expectancy at the adult stage, especially that of male offspring.

Conclusions. Folic acid, when consumed in excess by Drosophila melanogaster individuals at the larval stage for several generations, has genotype- and sex-dependent effects, including negative ones, on the life expectancy of the imago--offspring of exposed parents.