CELLULAR-DISTRIBUTION OF SEA-URCHIN ANTIBACTERIAL ACTIVITY

Paracentratus lividus circulating coelomocytes could be separated by a discontinuous sodium-metrizoate gradient. Amoebocytes and red spherule cells were separated in an almost pure population, whereas colourless spherule cells were distributed at different density levels suggesting that several morphological or functional types constitute this cellular category. Vibratile cells co-occur with amoebocytes, colourless and red spherule cells in a single heterogeneous fraction. Studies with the separated bands indicate that antibacterial activity against gram negative marine bacteria is present in each cellular fraction. However, the highest degree of bacterial growth inhibition was produced by amoebocytes from band A and red spherule cells from band F. Amoebocytes most probably exerted their antibacterial function by lysozyme-like molecules, while red spherule cells do not possess this enzyme.