904
As to their responsiveness to sonication , the best two promoters were then compared to clone 880 - 8 , a derivative from clone 880 that was created by random introduction of point mutations and was shown to have an improved response to X - ray irradiation .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None