Target-selected mutant screen by TILLING in Drosophila

Area of Science:

• Genetics and Genomics
• Molecular Biology
• Drosophila melanogaster research

Background:

• The completion of the Drosophila melanogaster genome sequence enables targeted mutation generation.
• Existing methods have characterized mutations in approximately 6000 of 15,000 annotated fly genes.
• A significant portion of these genes are essential for organism viability.

Purpose of the Study:

• To develop an efficient method for generating mutations in specific Drosophila genes.
• To utilize a reverse genetics approach for large-scale point mutation detection.
• To validate the effectiveness of Cel-I-mediated heteroduplex cleavage for mutation screening.

Main Methods:

• Established a genomic DNA library from 2086 ethyl methanesulfonate (EMS)-mutagenized Drosophila lines.
• Employed Cel-I-mediated heteroduplex cleavage for large-scale detection of point mutations.
• Screened the library for mutations in three target genes under varying mutagenesis conditions.

Main Results:

• Screened 6.1 Mb of DNA, identifying 44 mutations across two mutagenesis conditions.
• Optimal conditions achieved an average mutation detection rate of one per 156 kb.
• For an essential gene, 20% (5 of 25) of identified mutations resulted in lethality, indicating high gene inactivation frequency.

Conclusions:

• Cel-I-mediated TILLING is an efficient method for obtaining mutations in genes of interest in Drosophila.
• This approach facilitates reverse genetics strategies in Drosophila research.
• The study confirms EMS mutagenesis's high efficiency in causing gene inactivation.