Identification of Quantitative Trait Loci and Candidate Genes Influencing Ethanol Sensitivity in Honey Bees

Abstract

Invertebrate models have greatly furthered our understanding of ethanol sensitivity and alcohol addiction. The honey bee (Apis mellifera), a widely used behavioral model, is valuable for comparative studies. A quantitative trait locus (QTL) mapping experiment was designed to identify QTL and genes influencing ethanol vapor sensitivity. A backcross mating between ethanol-sensitive and resistant lines resulted in worker offspring that were tested for sensitivity to the sedative effects of alcohol. A linkage map was constructed with over 500 amplified fragment length polymorphism (AFLP) and sequence-tagged site (STS) markers. Four QTL were identified from three linkage groups with log of odds ratio (LOD) scores of 2.28, 2.26, 2.23, and 2.02. DNA from markers within and near QTL were cloned and sequenced, and this data was utilized to integrate our map with the physical honey bee genome. Many candidate genes were identified that influence synaptic transmission, neuronal growth, and detoxification. Others affect lipid synthesis, apoptosis, alcohol metabolism, cAMP signaling, and electron transport. These results are relevant because they present the first search for QTL that affect resistance to acute ethanol exposure in an invertebrate, could be useful for comparative genomic purposes, and lend credence to the use of honey bees as biomedical models of alcohol metabolism and sensitivity.

A Genetic Analysis of the Stinging and Guarding Behaviors of the Honey Bee

“…The physical size of the honey bee genome is approximately 262 Mb Weinstock et al 2006). The estimated recombination rate for the EAA map (16.3 cM/Mb) and EAE map (15.7 cM/ Mb) are similar to other mapping studies in honey bees (Lapidge et al 2002;Ammons and Hunt 2008;Beye et al 2006;Solignac et al 2007). …”

“…For the bees seen performing guarding behaviors, abdomens from 88 individuals were taken from the Africanized backcross. DNA extraction and quantification was performed as in Ammons and Hunt (2008).…”

The Genetics of Alcohol Responses of Invertebrate Model Systems

“…In general, both methods scored the mutations as having the same overall effects on sensitivity and tolerance. Bees can be exposed to ethanol vapor in the same ways flies can (Ammons & Hunt, 2008).…”

A verification of previously identified QTLs for cocaine-induced activation using a panel of B6.A chromosome substitution strains (CSS) and A/J x C57Bl/6J F2 mice

“…A QTL approach, which can isolate multiple genes that individually account for small amounts of variance, has been used to identify chromosomal regions and potential candidate genes associated with the effects of multiple drugs of abuse including cocaine, ethanol, and morphine (Gill and Boyle 2008;Hitzemann et al 2008;Radcliffe et al 2007;Doyle et al 2008). To date, QTL analysis has been most extensively used in genetic analyses of alcohol-related phenotypes (Hitzemann et al 2008;Bennett et al 2008;Radcliffe et al 2007;Ammons and Hunt 2008). A small number of studies have mapped QTLs related to cocaine-induced changes in locomotor activation and neurochemistry using the BXD recombinant inbred (RI) panel of strains derived from a cross between the C57BL/6J (B6) and the DBA/2J (D2) (Jones et al 1999;Tolliver et al 1994;Miner and Marley 1995;Phillips et al 1998).…”