The present study investigated cDNA chimeras using two closely related members of the rice secretory protein gene family as an example. The chimeras detected in initial cDNA products that were amplified using LA Taq polymerase involved two categories: single-site type and multiple-site type with the frequency being about 20% and 3%, respectively. Further investigation revealed that PCR buffer additives and type of DNA polymerase had a major effect on the formation of chimeras in mixed-template amplification. Heteroduplex repair by microbial DNA repair systems in cDNA cloning was confirmed to produce the chimeras too, but it was not the major source.
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