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Yeast artificial chromosome libraries containing large inserts from mouse and human DNA.
Z Larin1, A P Monaco, H Lehrach
1Genome Analysis Laboratory, Imperial Cancer Research Fund, London, United Kingdom.
Summary
Researchers developed a new method to create larger yeast artificial chromosome (YAC) libraries. This technique, using polyamines, significantly increased DNA insert sizes, aiding in gene mapping and cloning.
Area of Science:
- Molecular Biology
- Genomics
- Biotechnology
Background:
- Constructing yeast artificial chromosome (YAC) libraries with large DNA inserts (>400 kb) is challenging using standard low-melting-point agarose fractionation.
- High molecular weight DNA is susceptible to degradation when agarose is melted, limiting YAC insert sizes.
Purpose of the Study:
- To improve the construction of YAC libraries with larger average insert sizes.
- To identify methods to protect high molecular weight DNA during agarose melting for YAC cloning.
Main Methods:
- Mock cloning experiments using yeast chromosomes to test DNA protection strategies.
- Incorporation of polyamines during the agarose melting and DNA manipulation steps.
- Construction of YAC libraries from mouse and human DNA.
- Replication of YAC libraries onto high-density filters using a multipin transfer device.
- Screening of filter replicas by hybridization to isolate YAC clones.
Main Results:
- Polyamines were found to protect high molecular weight DNA from degradation during agarose melting.
- YAC libraries with average insert sizes of 700 kb (mouse) and 620 kb (human) were successfully constructed.
- 70 mouse YAC clones (31 loci) and 132 human YAC clones (49 loci) were isolated using high-density screening.
Conclusions:
- The addition of polyamines is crucial for protecting DNA and achieving larger insert sizes in YAC libraries.
- This optimized YAC library construction method facilitates efficient genome exploration and gene isolation.