Do brine shrimp diagnose cystic fibrosis?

The nauplii of the brine shrimp Artemia salina are dependent upon the function of their salt gland to maintain osmotic pressure within narrow limits. A number of drugs interfere with this function and are lethal to the nauplii. Saliva and serum from normal persons, patients with cystic fibrosis, and obligate heterozygotes were tested for lethal effect against brine shrimp nauplii. At salt concentrations between 100 mM and 2.5 no difference was found among the phenotypes. At lower concentrations a difference was noted occasionally between some normal subjects and some individuals carrying one or two genes for cystic fibrosis. Data from an independent series of experiments indicate that the naupliar deaths result from distorted ratios of Na+/K+ and not from a specific gene product. No difference was noted in the O2 uptake of nauplii treated with saliva or serum obtained from normal subjects, patients with cystic fibrosis, or obligate heterozygotes.