Fucoidan stimulates cell division in the amebocyte-producing organ of the schistosome-transmitting snail Biomphalaria glabrata

Abstract

Adult Salvador (schistosome-resistant) strain Biomphalaria glabrata snails were injected with 5μl of 10mg/ml solutions of the sulfated polysaccharides λ carageenan, dextran sulfate, fucoidan, and heparin, the nonsulfated polysaccharide laminarin, and the monosaccharides L-fucose and L-galactose, and mitotic activity in the amebocyte-producing organ (APO) was measured in histological sections at 24h post injection. Among the substances tested, only fucoidan induced elevated mitotic activity. Desulfated fucoidan was not mitogenic, indicating that sulfate groups are required for activity. Schistosome-susceptible M-line snails possessed minimal or no hematopoietic tissue in their APO, which did not respond to fucoidan. Immersion of juvenile Salvador snails in 1 or 10mg/ml solutions of fucoidan for 3h did not elevate mitotic activity at 24h post immersion, suggesting that the external and digestive tract epithelia of B. glabrata are impermeable to this molecule. These results provide support for the hypothesis that fucosylated glycans on the tegument and in excretory–secretory products of sporocysts of Schistosoma mansoni are in part responsible for increased mitotic activity in the APO of B. glabrata infected with this trematode or injected with its extracts.