Dataset Information

Adult Phenotypes and Gene Expression in the Brain at Single Cell Resolution After Developmental Alcohol Exposure in Drosophila

ABSTRACT: Fetal alcohol exposure can lead to developmental abnormalities, intellectual disability, and behavioral changes, collectively termed fetal alcohol spectrum disorder (FASD). In 2015, the CDC found that 1 in 10 pregnant women report alcohol use and more than 3 million women in the USA are at risk of exposing their developing baby to alcohol. Identifying genetic risk alleles for FASD is challenging, since time, dose and frequency of exposure are often unknown, and phenotypic manifestations of FASD are diverse and become evident long after exposure. Drosophila melanogaster presents an excellent model to study developmental effects of alcohol exposure, because virtually unlimited numbers of individuals of the same genotype can be reared rapidly and economically under well-controlled environmental conditions without regulatory restrictions. Furthermore, flies exposed to alcohol undergo physiological and behavioral changes that resemble human alcohol-related phenotypes. Flies reared on ethanol-supplemented medium show decreased viability, reduced sensitivity to ethanol, and disrupted sleep and activity patterns. To assess alcohol-modulated gene expression in the brains of flies reared on alcohol, we performed single cell RNA sequencing and resolved cell clusters with differentially expressed genes representing distinct neuronal and glial populations. We observed extensive sexual dimorphism. Two clusters associated with glial biomarkers showed greater differential gene expression in males, whereas mushroom body-derived cells exhibited a greater degree of differential gene expression in females. Results obtained from these studies provide a blueprint for translational studies on alcohol-induced effects on gene expression in the brain that may contribute to or result from FASD in human populations.

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE172231 | GEO | 2021/08/11

REPOSITORIES: GEO

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Project description:Alcoholism is a complex disorder determined by interactions between genetic and environmental risk factors. Drosophila represents a powerful model system to dissect the genetic architecture of alcohol sensitivity, as large numbers of flies can readily be reared in defined genetic backgrounds and under controlled environmental conditions. Furthermore, flies exposed to ethanol undergo physiological and behavioral changes that resemble human alcohol intoxication, including loss of postural control, sedation, and development of tolerance. We performed artificial selection for alcohol sensitivity for 25 generations and created duplicate selection lines that are either highly sensitive or resistant to ethanol exposure along with unselected control lines. We used whole genome expression analysis to identify 1,678 probe sets with different expression levels between the divergent lines, pooled across replicates, at a false discovery rate of q < 0.001. We assessed to what extent genes with altered transcriptional regulation might be causally associated with ethanol sensitivity by measuring alcohol sensitivity of 37 co-isogenic P-element insertional mutations in 35 candidate genes, and found that 32 of these mutants differed in sensitivity to ethanol exposure from their co-isogenic controls. Furthermore, 23 of these novel genes have human orthologues. Combining whole genome expression profiling with selection for genetically divergent lines is an effective approach for identifying candidate genes that affect complex traits, such as alcohol sensitivity. Because of evolutionary conservation of function, it is likely that human orthologues of genes affecting alcohol sensitivity in Drosophila may contribute to alcohol-associated phenotypes in humans. Experiment Overall Design: Starting with flies from Raleigh natural population (see material and methods) we performed artificial selection for alcohol sensitivity for 35 generation. In each generations we scored 60 males and females, separately, from each line (resistant, sensitive, and control)using inebriometer, and the 20 highest-scoring flies from the resistant lines and the 20 lowest-scoring flies from the sensitive lines were selected as parents for the next generation. Control line flies were scored each generation and 20 random flies were used as parents. Experiment Overall Design: At generation 25, two replicates of 15 three-five day old virgin males and females were collected from each selection line. Total RNA was extracted from the 24 samples . Biotinylated cRNA probes were hybridized to high density oligonucleotide microarrays (Affymetrix, Inc. Drosophila GeneChip 2.0) and visualized with a streptavidin-phycoerythrin conjugate, as described in the Affymetrix GeneChip Expression Analysis Technical Manual (2000), using internal references for quantification. The quantitative estimate of expression of each probe set is the Signal (Sig) metric, as described in the Affymetrix Microarray Suite, Version 5.0.