8591
Finally , although the asd gene encodes an enzyme , aspartate-semialdehyde dehydrogenase , that participates in the synthesis of methionine , lysine and threonine , transcription levels of the asd gene remain constant even when the concentrations of these amino acids are varied .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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