Primary cultures of embryonic cells from the snail Biomphalaria glabrata

Hemocyte-like cells in larvae of the freshwater snail Biomphalaria glabrata (Mollusca: Panpulmonata)

Despite undergoing development within a germfree egg capsule, embryos and larvae of the freshwater snail Biomphalaria glabrata possess passive immune protection in the form of parentally-derived antimicrobial proteins in the perivitelline fluid. However, the point at which larvae begin to form their own internal defense system (IDS), which consists of both plasma proteins and hemocytes, is not known. In this study, hemocyte-like cells were observed in mechanically-disrupted late trochophores and veligers of the BS-90 strain of B. glabrata. These cells showed the properties of glass adherence, spreading, motility, and binding and phagocytosing polystyrene microspheres. No hemocyte-like cells were recovered from the early trochophore stage, and therefore their formation first occurs during subsequent maturation. Numbers of hemocyte-like cells increased during larval development. Although the functional significance of these cells is not known, they may represent the initial cellular component of the IDS.

Molluscan cells in culture: primary cell cultures and cell lines

In vitro cell culture systems from molluscs have significantly contributed to our basic understanding of complex physiological processes occurring within or between tissue-specific cells, yielding information unattainable using intact animal models. In vitro cultures of neuronal cells from gastropods show how simplified cell models can inform our understanding of complex networks in intact organisms. Primary cell cultures from marine and freshwater bivalve and gastropod species are used as biomonitors for environmental contaminants, as models for gene transfer technologies, and for studies of innate immunity and neoplastic disease. Despite efforts to isolate proliferative cell lines from molluscs, the snail Biomphalaria glabrata Say, 1818 embryonic (Bge) cell line is the only existing cell line originating from any molluscan species. Taking an organ systems approach, this review summarizes efforts to establish molluscan cell cultures and describes the varied applications of primary cell cultures in research. Because of the unique status of the Bge cell line, an account is presented of the establishment of this cell line, and of how these cells have contributed to our understanding of snail host-parasite interactions. Finally, we detail the difficulties commonly encountered in efforts to establish cell lines from molluscs and discuss how these difficulties might be overcome.

In vitro cultivation of cells from ovotestis tissue of pigmented Biomphalaria glabrata

Cells derived from ovotestis tissue of pigmented Biomphalaria glabrata, Puerto Rican strain were cultured in double diluted GIT medium supplemented with modification of amino acids components of pigmented B. glabrata, ovotestis and mid-gut region and 3% inactivated fetal calf serum. As a result, two types of cells, epithelial and fibroblastic like cells increased in number during the cultivation. It seem that the medium used in this study is a suitable medium for cultivation of cells from ovotestis of pigemeted B. glabrata. These two types of cells have been maintained by successive transplantation for over 3 passages.

In vitro cultivation of cells and a microsporidian parasite of Biomphalaria glabrata (Pulmonata: Basommatophora)

Cells from juvenile heart and gonads of B. glabrata have been grown in vitro for more than 1 year. These cell cultures are not actively mitotic but show other characteristics normal for metazoan cells in culture. They are tolerant of widely variable culture conditions. Challenges with mitogens, mutagens, and altered cyclic nucleotide levels have failed to induce mitosis. A microsporidian parasite grows intracellularly in vitro. The ultrastructural details of sporogeny and pansporoblastic maturation are described. Several pansporoblasts can occur in one snail cell; maturation of spores within a pansporoblast is not synchronous, which is a highly unusual feature. Time-lapse cinemicrography reveals engulfment of free spores by snail cells. Polar tube and sporoplasm release are reported photographically. Drug therapy failed to eliminate the protozoan. The potential value of microsporidia in schistosome control programs is evaluated as slight.

Histochemical demonstration of acetylcholinesterase in sporocysts of Schistosoma mansoni (Trematoda)

The distribution of acetylcholinesterase in mother and daughter sporocysts of Schistosoma mansoni was studied histochemically. In young mother sporocysts derived from miracidia cultured in vitro the miracidial neural mass and flame cells were shown to persist. The nerve trunks and commissures, as well as papillae, are apparently lost in the transformation process. In young daughter sporocysts freshly dissected from mother sporocysts there was little enzyme activity except for a sparse distribution in the tegument. After cultivation, intense enzyme activity was associated with developing cercarial embryos. A similar distribution of activity was observed in older daughter sporocysts obtained from the digestive gland of snails. No evidence of flame cells, neural mass, or commissures was detected in daughter sporocysts by the methods employed.