Arsenobetaine(As B) is a non-toxic organoarsenical identiied as a major arsenic species in marine animals and a number of terrestrial mushrooms.Since its irst identiication nearly 40 years ago,numerous studies investigating the biosynthesis and function of As B have been carried out,although molecular mechanisms have not been fully elucidated.Where and how is As B formed? Why do marine animals acquire high concentrations of As B? his review briely summarizes the current progress of As B research toward understanding its origin,function and the putative pathways for its biosynthesis.his paper also suggests potential future studies in the atempt to solve the As B mystery. Arsenobetaine (As B) is a non-toxic organoarsenical identiied as a major arsenic species in marine animals and a number of terrestrial mushrooms.Since its irst identiication nearly 40 years ago, numerous studies investigating the biosynthesis and function of As B have been carried out , although molecular mechanisms have not been fully elucidated. Where and how is As B formed? Why do marine animals acquire high concentrations of As B? his review briely summarizes the current progress of As B research toward understanding its origin, function and the putative pathways for its biosynthesis.his paper also suggests potential future studies in the atempt to solve the As B mystery.