Parenteral injection into mice of a toxic pentapeptide isolated from the cyanobacterium Microcystis aeruginosa induced thrombocytopenia, pulmonary thrombi, and hepatic congestion. The lethality of the toxin was unaffected by several anticoagulants. The acute liver damage that follows injection of the toxin has been attributed to direct action on liver cells but may be due to hypoxemia, heart failure, and shock.

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The marine dinoflageDlate Amphidinium carterae (Plymouth 450) releases several water-soluble peridinin-chlorophyDl a proteins after freezethawing. These chromoproteins have a molecular weight of 39.2 x 103 and are comprised of noncovalently bound peridinin and chlorophyD a and a nonoligomeric protein. They Bode (3) and Bode and Hastings (4) subsequently found that clarified aqueous extracts of Gonyaulax polyedra were red. They partially purified the chromoprotein and established that the red color was due to peridinin bound to protein. Haidak et al. (9) further demonstrated that the G. polyedra chromoprotein had a molecular weight of about 38,000, and that it contained both peridinin and Chl a. Peridinin-Chl a proteins have also been obtained from other unialgal dinoflagellate cultures and from the endosymbiotic dinoflagellates of the giant clam. Preliminary studies (14) showed that these chromoproteins contained peridinin, Chl a, and protein in stoichiometric ratios and exhibited efficient sensitization of Chl a fluorescence by peridininabsorbed light. Each of these chromoproteins chromatographed as reasonably symmetrically eluting species on Sephadex, but could be electrophoretically resolved into a number of components, all containing peridinin and Chl a.The marine dinoflagellate Amphidinium carterae (Plymouth 450) was selected for detailed studies. A. carterae is easily cultured on a large scale and provides high yields of the peridinin-Chl a proteins predominantly as a single component. It yields a set of six PCPs5 of about 39,000 mol wt, and this report is concerned with the detailed properties of three of the PCPs.MATERIALS AND METHODS Reagents. Diethylaminoethyl cellulose Whatman) was obtained from Reeve Angel, Sephadex gels from Pharmacia Fine Chemicals, and all antibiotics were from Sigma Chemical Co. Ampholines were purchased from LKB Produkter. Acrylamide and methylene bisacrylamide were recrystallized from chloroform and acetone, respectively (23). All other chemicals were reagent grade and are commonly available.

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