Unknown,Transcriptomics,Genomics,Proteomics

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Genome features of “Dark-fly”, a Drosophila line reared long-term in a dark environment

ABSTRACT: To address the molecular mechanisms underlying environmental adaptation, we studied a Drosophila melanogaster line, termed Dark-fly, which has been maintained in constant dark conditions for 57 years (1400 generations).The structural gene copy number changes between the dark fly and its control were assessed by aCGH array. The comparison showed that hundreds of genes in the dark fly bear duplications or deletions relative to the control line. The copy number increase and decrease in the dark flies were determined by two-channel array hybridization with the control line. In addition to biological replicates, a Cy5-Cy3 dye swap was performed.Self-hybridization was also conducted to serve as a quality control.

ORGANISM(S): Drosophila melanogaster

SUBMITTER: Jun Zhou

PROVIDER: E-GEOD-35418 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Copy number variants (CNVs) reshape gene structure, modulate gene expression, and contribute to significant phenotypic variation. Previous studies have revealed CNV patterns in natural populations of Drosophila melanogaster and suggested that selection and mutational bias shape genomic patterns of CNV. While previous CNV studies focused on heterogeneous strains, here we established a number of second-chromosome substitution lines to uncover CNV characteristics when homozygous. The percentage of genes harboring CNVs is higher than found in previous studies. More CNVs are detected in homozygous than heterozygous substitution strains, suggesting the comparative genomic hybridization arrays underestimate CNV owing to heterozygous masking. We incorporated previous gene expression data collected from some of the same substitution lines to investigate relationships between CNV gene dosage and expression. Most genes present in CNVs show no evidence of increased or diminished transcription, and the fraction of such dosage-insensitive CNVs is greater in heterozygotes. More than 70% of the dosage-sensitive CNVs are recessive with undetectable effects on transcription in heterozygotes. A deficiency of singletons in recessive dosage-sensitive CNVs supports the hypothesis that most CNVs are subject to negative selection. On the other hand, relaxed purifying selection might account for the higher number of protein-protein interactions in dosage insensitive CNVs than in dosage-sensitive CNVs. Dosage-sensitive CNVs that are up-regulated and down-regulated coincide with copy number increases and decreases. Our results help clarify the relation between CNV dosage and gene expression in the D. melanogaster genome. To determine copy number variation, the genomic DNA from five homozygous and two heterozygous second chromosome substitution lines were extracted and compared to another second chromosome substitution line. Gene expression levels can be referred to at Series GSE12191 (Lemos et al. (2008) PMID:18791071).