Hydrolytic enzymes associated with the granular haemocytes of the marine mussel Mytilus edulis.
The ultrastructural localization of a range of hydrolytic enzymes has been investigated in the granular haemocytes of the marine mussel Mytilus edulis. Arylsulphatase activity and immunocytochemical localization of beta-glucuronidase and elastase were demonstrated within the large granules of the haemocytes. Lysozyme and cathepsin B were both localized within all sizes of granule, however, at high dilutions the primary antibody against lysozyme was also restricted to the large granules. The labelling density for cathepsin B antibody tended to be very low. Antibodies for cathepsin G showed a clear, discrete labelling which was restricted to the granules of haemocytes containing small granules. The fact that antibodies raised against human proteinases recognize invertebrate enzymes suggests that there must be a certain degree of structural similarity between the human proteinases and the enzymes present in the mussel haemocytes indicating either convergence or conservation of the enzyme molecules. The presence of a range of hydrolytic enzymes including proteinases, glycosidases and sulphatases within the large granules shows that these granules are a form of lysosome. The reduction in activity of lysosomal enzymes in haemocytes following adhesion to glass is evidence for release of the enzymes from the granules (degranulation). The possibility of a serine protease being specifically associated with the small granules and its role as a cytolysin are discussed.
Pipe
R K
RK
Natural Environment Research Council, Plymouth Marine Laboratory, Citadel Hill, UK.
D000818:Animals; D000906:Antibodies / Q000378:metabolism; D001192:Arylsulfatases / Q000378:metabolism; D049872:Bivalvia / Q000201:enzymology*; D002401:Cathepsin B / Q000378:metabolism; D005966:Glucuronidase / Q000378:metabolism; D006434:Hemocytes / Q000201:enzymology*; D007150:Immunohistochemistry; D008247:Lysosomes / Q000201:enzymology; D009113:Muramidase / Q000378:metabolism
D000906:Antibodies; D001192:Arylsulfatases; D009113:Muramidase; D005966:Glucuronidase; D002401:Cathepsin B