Functional and structural characterization of hemocytes of the solitary ascidian,Halocynthia roretzi

✍ Scribed by Azumi, Kaoru ;Satoh, Noriyuki ;Yokosawa, Hideyoshi

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 952 KB
• Volume: 265
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402650312

✦ Synopsis

Abstract

In invertebrates, hemocytes play important roles in defense mechanisms. The hemocytes of a solitary ascidian, Halocynthia roretzi, are a source of two antibacterial substances (halocyamines) and a lipopolysaccharide‐binding (LPS‐binding) hemagglutinin that is capable of agglutinating various bacteria. Furthermore, a metallo‐protease is released from the hemocytes in response to treatment with LPS, a calcium ionophore, or phorbol ester. In the present study, we attempted to fractionate the hemocytes to determine which of them contain the LPS‐binding hemagglutinin and release the metallo‐protease in response to various stimuli. The hemocytes of H. roretzi can be separated into five groups (L1‐L5) by discontinuous density gradient centrifugation in a solution of bovine serum albumin. The various populations of hemocytes exhibit structural differences that can be monitored by electron microscopy and flow cytometric analysis. The LPS‐binding hemagglutinin, together with halocyamines, was found in group L5, which consists of only one type of hemocyte. The hemocytes in groups L1, L3, and L4 released the metallo‐protease in response to various stimuli, whereas at least those in group L5 did not. These results indicate that the various groups of hemocytes of H. roretzi can be distinguished functionally from one another on the basis of cellular responses and the ability to produce defense substances. © 1993 Wiley‐Liss, Inc.