Truncated fragments in polymerase chain reaction-based DNA sequencing

Area of Science:

• Molecular Biology
• Genomics
• Biochemistry

Background:

• Standard dye-primer protocols for DNA sequencing can encounter interpretation problems due to truncated DNA fragments.
• Even small amounts (0.2 mole-percentage) of truncated fragments can significantly hinder accurate sequence analysis.

Purpose of the Study:

• To develop novel protocols for DNA sequencing that overcome the limitations posed by truncated fragments.
• To adapt sequencing methods for efficient automation and high-quality data generation.

Main Methods:

• Developed two dye-terminator sequencing protocols: one for single extension using T7 DNA polymerase and another for cycle sequencing.
• Incorporated biotinylated sequencing primers to avoid precipitation and facilitate automation.
• Utilized magnetic separation for fragment recovery, washing, and release via formamide, EDTA, and heat treatment prior to electrophoresis.

Main Results:

• The new dye-terminator protocols effectively eliminate sequence interpretation problems caused by truncated fragments.
• Achieved high-quality sequencing data, characterized by long reads and successful detection of polymorphisms.
• Demonstrated the suitability of the protocols for automated sequencing of PCR products using one-dye-labeled terminators.

Conclusions:

• The developed dye-terminator protocols offer a robust alternative to traditional dye-primer and internal labeling methods for DNA sequencing.
• These protocols enhance automation capabilities and improve the reliability of DNA sequencing, particularly for PCR products.
• The methods provide a valuable tool for accurate genetic analysis, including polymorphism identification.