Ascidian haemocytes are involved in many biological functions, such as immune defence, non self recognition, tunic synthesis and secretion of humoral factors, asexual reproduction. Although widely studied, doubts still exist about their classification and functions. In the blood of the colonial ascidian Botryllus schlosseri, at least eight different cell-types are present, traditionally grouped in four categories, i.e. lymphocyte-like cells, amoebocytes, vacuolated cells (morula cells and macrophage-like cells), storage cells (nephrocytes and pigment cells). Previous investigations on the histoenzymatic characteristics of Botryllus blood cells led us to distinguish two classes of immunocytes, i.e. morula cells and their precursors, able to mount cytotoxic reactions against non-self cells or particles, and hyaline amoebocytes and macrophage-like cells, involved in phagocytosis of foreign material. To further characterise haemocyte-types and their mutual relationships, we used a series of lectins as cell surface markers. Results indicate that haemocytes share a similar response towards most of lectins, being laelled or not labelled. Pagocytes have mannose residues, recognised by Narcissus pseudonarcissus agglutinin, on the membranes of their vacuoles, strengthening our previous hypothesis of a common differentition pathway of these cell-types. Morula cells are the only haemocytes recognised by peanut agglutinin, specific for galactose-N-acetyl-galactosamine residues, whereas granular amoebocytes show presence of N-acetyl-glucosamine and N-acetyl-lactosamine on their surface. Only pigment cells showed labelling by Ulex europaeus agglutinin-I which recognises fucose.

Lectin cytochemistry of the colonial ascidian Botryllus schlosseri haemocytes

BALLARIN, LORIANO;GASPARINI, FABIO;CIMA, FRANCESCA
2003

Abstract

Ascidian haemocytes are involved in many biological functions, such as immune defence, non self recognition, tunic synthesis and secretion of humoral factors, asexual reproduction. Although widely studied, doubts still exist about their classification and functions. In the blood of the colonial ascidian Botryllus schlosseri, at least eight different cell-types are present, traditionally grouped in four categories, i.e. lymphocyte-like cells, amoebocytes, vacuolated cells (morula cells and macrophage-like cells), storage cells (nephrocytes and pigment cells). Previous investigations on the histoenzymatic characteristics of Botryllus blood cells led us to distinguish two classes of immunocytes, i.e. morula cells and their precursors, able to mount cytotoxic reactions against non-self cells or particles, and hyaline amoebocytes and macrophage-like cells, involved in phagocytosis of foreign material. To further characterise haemocyte-types and their mutual relationships, we used a series of lectins as cell surface markers. Results indicate that haemocytes share a similar response towards most of lectins, being laelled or not labelled. Pagocytes have mannose residues, recognised by Narcissus pseudonarcissus agglutinin, on the membranes of their vacuoles, strengthening our previous hypothesis of a common differentition pathway of these cell-types. Morula cells are the only haemocytes recognised by peanut agglutinin, specific for galactose-N-acetyl-galactosamine residues, whereas granular amoebocytes show presence of N-acetyl-glucosamine and N-acetyl-lactosamine on their surface. Only pigment cells showed labelling by Ulex europaeus agglutinin-I which recognises fucose.
Proceedings of the 30th National Congress of the Italian Society of Histochemistry
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11577/2458314
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