. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CHOLINE REQUIREMENT OF MOINA 363 1200 r. CHOLINE (mg %) FIGURE 3. Relationship between the level of dietary choline and the average biomass of harvested populations of Moina macrocopa grown on artificial diets. Liver infusion was absent. Each point rep- resents an average of 20 observations. * = average biomass of populations grown on soy PC diet (Ex- periment II). DISCUSSION Choline clearly is a required nutrient for growth and survival of the micro- crustacean Moina macrocopa. In our artificial
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CHOLINE REQUIREMENT OF MOINA 363 1200 r. CHOLINE (mg %) FIGURE 3. Relationship between the level of dietary choline and the average biomass of harvested populations of Moina macrocopa grown on artificial diets. Liver infusion was absent. Each point rep- resents an average of 20 observations. * = average biomass of populations grown on soy PC diet (Ex- periment II). DISCUSSION Choline clearly is a required nutrient for growth and survival of the micro- crustacean Moina macrocopa. In our artificial diets, this nutrient made its major contribution via the lecithin in the particulate portion of the biphasic media. Dietary lecithin, as a source of lipid, probably also contributes to increased growth rates. D'Abramo (1979) found that increasing dietary fatty acids from to mg% enhances growth of Moina macrocopa. Our observation of 10-fold greater effec- tiveness of a particulate rather than a soluble source of choline is lower than the 60-fold greater effectiveness of particulates estimated by Provasoli and D'Agostino (1969) for brine shrimp, Anemia salina, grown on artificial media. Provasoli and D'Agostino, however, based their estimates on growth with soluble amino acids versus particulate egg albumin. In such a situation, the inefficiency of soluble nutrient sources may be compounded by the crustacean's inability to utilize protein as singular amino acids rather than as polypeptides. The population growth achieved by replacing the egg lecithin of the control diet with pure egg PE revealed that Moina macrocopa can efficiently synthesize choline via methylation of ethanolamine. This biosynthetic pathway is also described for the lobster Homarus americanus (Shieh, 1969). Use of this pathway alone, how- ever, reduces population growth of Moina by 30%. The greater nutritional value of pure soy PC versus pure egg PC was probably related to the different constituent fatty
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
