20594
Thus , when the exonuclease PNPase was absent , we found that the shorter tRNA ( Cys ) species increased and mature tRNA ( Cys ) decreased after mercury addition , but this proportion changed during the time analyzed .
 Chemical: Cys; Chemical: Cys; Chemical: mercury
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: Cys; Chemical: Cys; Chemical: mercury