CHIT1 and Gaucher disease: Among the genes differentially expressed in B. schlosseri when comparing filter-feeding adults with adults in takeover, we found that: (1) CTSD (Cathepsins D) is differentially more highly expressed in takeover zooids; (2) CHIT1 (Chitinase 1) is secreted by activated human macrophages and is markedly elevated in plasma of Gaucher disease patients.