Perkinsus marinus and dinoflagellate cultures, RNA isolation and cDNA construction Perkinsus marinus isolate ATCC 50439 and P. chesapeaki ATCC PRA-65 were grown in tissue culture flasks with liquid media, samples (3-4610 6 cells) were collected by centrifugation and total RNAs were isolated as reported previously [14] . Dinoflagellates Amphidinium carterae (CCMP1314) and Karlodinium veneficum (CCMP2778) were grown in f/2 seawater medium at 20uC at a 12 h:12 h light:dark photocycle with a photon flux of approximately 50 mE?m 22 s 21 . When the cultures were in the exponential growth phase, ,1610 6 cells were harvested and total RNAs isolated according to Zhang et al. [8] . These RNAs were used for cDNA synthesis as described previously [8] .