23100
The numerous researches have been actively conducted with respect to the toxic effects of anatoxin - a on mammals ; however , little research has aimed at its possible effects on aquatic plants , wherein well - structured nervous system is absent with the lack of various components of the acetylcholine mechanism .
 Chemical: anatoxin - a; Chemical: acetylcholine
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: anatoxin - a; Chemical: acetylcholine