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Interestingly , we found from electrophoretic mobility shift assays and transcriptional analysis that AfsQ1 / Q2 can also function as a repressor for nitrogen assimilation , and AfsQ1 can compete with GlnR for the promoter regions of glnA and nirB , suggesting the cross - regulation between AfsQ1 / Q2 and GlnR in nitrogen metabolism .
 Chemical: nitrogen; Chemical: nitrogen
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: nitrogen; Chemical: nitrogen