Comparison of Toxicities of Protogonyaulax Cells of Various Sizes

Abstract

Protogonyaulax cells collected from Ofunato Bay were fractionated into “20-30”, “30-40”, and “40-95” µm fractions by sieves having mesh sizes of 20, 30, 40 and 95 µm. In the case of P. tamarensis, the toxicity was 0.54-1.46 MU/104 cells for the “20-30” µm fraction, 1.14-2.43 MU/104 cells for the “30-40” µm fraction, and 1.14-2.55 MU/104 cells for the “40-95” µm fraction. Microscopic observations showed that most cells of the “20-30” µm fraction were over 30 µm in either cell length or width, whereas no comparable phenomena were observed for the two other fractions. Therefore it was presumed that the cells of the “20-30” µm fraction were younger ones equipped with soft theca or cell membranes. Similar attempts were made to separate P. catenella cells into three fractions, but their toxicities were too low to be assayed. © 1982, The Japanese Society of Fisheries Science. All rights reserved.