Humoral opsonins of the tunicate, Pyura stolonifera

This study characterizes humoral opsonins from the tunicate, Pyura stolonif era. The predominant opsonic components in P. stolonifera hemolymph were fo und to be calcium-dependent lectins with broad carbohydrate specificities. The opsonic lectins were purified by carbohydrate affinity chromatography w hich eluted a complex pattern of proteins ranging in molecular mass from 80 to >200 kDa. Reducing and two dimensional SDS-PAGE indicated that the dive rsity of mature lectins evident under non-reducing conditions resulted from the differential oligomerization of two polypeptide sub-units (35 and 22 k Da). In addition to lectin-mediated opsonic activity, hemolymph was also fo und to contain proteolytically activated opsonins. These data suggest that multiple, possibly interactive opsonic systems co-exist in P. stolonifera. (C) 2001 Elsevier Science Ltd. All rights reserved.