Studies on a Marine Parasitic Ciliate 



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Fig. 1. Growth of clone T16 in Eagle's maintenance medium and in tissue 

 cultures of the human cell line KB. 



cultures. Figure 2 shows the reproducibihty of such growth ex- 

 periments. T16 strain was given grunt monolayer cultures as 

 food in two independent experiments. In both cases the growth 

 rates are comparable while the final yields depend on the number 

 of fish cells offered. For comparison of the growth rates of para- 

 sitic and saprozooic animals, growth obtained in Melnick's mam- 

 malian tissue culture medium is indicated by the third curve. 



The effect of temperature on ciliate production in Melnick's 

 medium, prepared with Hank's salt solution, was measured over 

 twelve successive passages. The data obtained are represented 

 in Table 1. T5 was better fit to grow saprozoically than the canni- 

 balistic strain T16. 



Table 2 compares growth of both strains in the saprozooic 

 feeding system in media of different salinities and at different 

 temperatures. Final yields of 50 ml standard cultures were de- 

 termined after seven days in twelve successive passages. Both 

 strains exhibited better growth in the low salinity media. The 

 effect of temperature was clearly expressed in the low salinity 

 media but is insignificant in the seawater media, in wliich the 

 difference in cell production of both strains was barely recog- 

 nizable. Microscopial obserxations re\ealcd tliat in T5 a weak 

 selfing took place occasionally in Melnick's seawater cultures. 



