Two morphologically distinct blood cell types (hemocytes), Type I and Type II were found coexisting in hemolymph from two kinds of snails, Oncomelania nosophora strain, viz. from the Nirasaki strain (schistosome-resistant snail) and the Kisarazu strain (schistosome-susceptible snail). Ten min after inoculation of SRBC, the majority of Type I cells from Nirasaki strain flattened and spread over the surface of the glass plate by extending pseudopodia. In the Kisarazu strain, Type I cells adhered to the surface of substrate with spike-like filopodia, but did not form spreading lamellipodia. Type I cell from the Nirasaki strain phagocytosed SRBC but that from the Kisarazu strain did not. The starting time of recognition of foreign materials was slightly different in the Type I hemocytes from the two strains. Type II cells from both strains were round and lymphocyte-like. Ten or sixty min after incubation, Type II cells from neither strain adhered to the surface of substrate or SRBC, and did not phagocytose SRBC. Type II cells from the Nirasaki strain were quite similar to those from the Kisarazu strain. We concluded that Type I cells from the schistosome-resistant snail, Nirasaki strain, possessed higher phagocytic activity than those from the susceptible snail, Kisarazu strain, despite the morphological similarities of the hemocytes from both strains.
Several morphological and functional aspects of blood cells and their formation in terrestrial gastropods are reviewed and discussed. Terrestrial gastropods lack a specialized haemopoietic organ, and blood cell formation occurs within the connective tissue and vascular system. Their blood cells are usually classified into 2 types, mainly spreading amoebocytes (macrophage-like) and round cells (lymphocyte-like). The main functions of blood cells are cellular defence (phagocytosis and encapsulation) and tissue repair. At least 2 types of molecules, foreign body molecules and serum molecules (opsonin and agglutinin), may be present on the plasma membrane of phagocytic cells. These molecules enable blood cells to recognize and ingest foreign particles. Ingested materials are then digested in the lysosomal system.
To clarify the phylogenetic position of Xenoturbella bocki and hemichordates (Balanoglossus carnosus and Saccoglossus kowalevskii), which occupy an ambiguous evolutionary position between vertebrates and invertebrates, we expanded a pre-existing baseline vertebrate data set by incorporating randomly selected invertebrates. Based on nucleotide content calculated from complete mitochondrial genomes, invertebrates were classified into two groups, high C/G and low C/G, with vertebrates placed within the high-C/G invertebrate group. X. bocki and hemichordates (B. carnosus and S. kowalevskii) also fell into the high-C/G invertebrate group. We also analyzed amino acid composition and nucleotide content of complete mitochondrial genomes or 16S rRNA genes using Ward's clustering method and neighbor-joining. In the resulting phylogenetic trees, invertebrates are classified into high C/G and low C/G categories, and vertebrates are divided into terrestrial and aquatic groups. In addition, X. bocki and representative hemichordates B. carnosus and S. kowalevskii appear to be more closely related to vertebrates than to invertebrates.
The body surface mucus from the land slug, Incilaria fruhstorferi, not only opsonized sheep red blood cells (SRBC) and agglutinated human types A and B erythrocytes (HRBC) but also caused hemolysis of B type HRBC 12 h after agglutination. The mucus-induced hemagglutination was specifically inhibited by a low concentration of N-acetyl D-galactosamine (GalNAc), and all of this activity was completely inactivated by heating at 56 degrees C for 30 min. SDS-polyacrylamide gel electrophoresis of water soluble fraction of the mucus showed that this fraction contained several proteins, the molecular mass of the main band being 35 KD.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.