QTL and candidate genes influencing ethanol sensitivity in honey bees
Abstract
A subset (3-5) of candidate genes identified from quantitative trait loci (QTL) for defensive behavior in honey bees (Apis mellifera L.) are homologous to genes known to influence ethanol sensitivity in other organisms. To investigate this possible link between aggression/defense and ethanol sensitivity, assays were developed to evaluate ethanol vapor responses in worker bees from a low-defensive (gentle) colony and a high-defensive colony. Defensive workers exhibited characteristic signs of ethanol-induced sedation significantly faster than gentle workers upon exposure to ethanol vapor. The presence of ethanol high-sensitive (defensive) and low-sensitive (gentle) lines allowed a QTL mapping experiment for ethanol sensitivity to be undertaken as well. These lines were mated in a backcross design to produce worker offspring. To assay the potential link between aggression and ethanol sensitivity these workers were screened with sequence-tagged site (STS) markers linked to three defensive QTL, and their genotypes were tested for associations with ethanol sensitivity. There were no significant results, indicating that these defensive QTL were not having a pleiotropic effect on ethanol sensitivity. However, it is possible that unidentified defensive QTL were mediating these effects. To identify QTL contributing to ethanol sensitivity, the backcross worker population was assayed for sensitivity and their DNA was individually extracted. Polymerase chain reactions utilizing this DNA generated AFLP (amplified fragment length polymorphism) markers. A linkage map was constructed with over 500 AFLP and STS (sequence-tagged site) markers. QTL mapping identified three QTL from two linkage groups with LOD (log of odd ratio) scores of 2.44, 2.28, and 2.23. Markers from QTL were cloned and sequenced. Clone and STS sequences were utilized to integrate our map with the physical genome. Two QTL were mapped to chromosome 15. One was mapped to chromosome 16. Most candidate genes with links to ethanol sensitivity influence synaptic transmission, neuronal growth, lipid synthesis, and detoxification. Others affect apoptosis, alcohol metabolism, cAMP signaling, and electron transport. Identified QTL and candidate genes for ethanol sensitivity are relevant for genomic and physiological comparisons with other invertebrate models of alcoholism.
Degree
Ph.D.
Advisors
Hunt, Purdue University.
Subject Area
Molecular biology|Entomology|Genetics
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