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In the presence of 1 mM Ni ( 2 + ) , reactive oxygen species ( ROS ) generation ( indicated by the level of malondialdehyde ) increased to 323 % and histone acetylation decreased to 32 % .
 Chemical: Ni ( 2 + ); Chemical: oxygen; Chemical: malondialdehyde
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: Ni ( 2 + ); Chemical: oxygen; Chemical: malondialdehyde