The freshwater snail Biomphalaria glabrata is an intermediate host of the
trematode Schistosoma mansoni. However, some strains of B. glabrata are
resistant to successful infection by S. mansoni larvae. The present work
examines the profile of organic acids present in S. mansoni-resistant and
-susceptible strains of B. glabrata, in order to determine whether the type
of organic acid present is related to susceptibility. The organic acids
were extracted from the hemolymph of two susceptible B. glabrata strains
(PR, Puerto Rico and Ba, Jacobina-Bahia from Brazil), and from the
resistant strains 13-16-R1 and 10R2, using solid phase extraction
procedures followed by high performance liquid chromatography. The organic
acids obtained were analyzed and identified by comparison with known
standards. Pyruvate, lactate, succinate, malate, fumarate, acetate,
propionate, beta-hydroxybutyrate and acetoacetate were detected in all
hemolymph samples. Under standard conditions, the concentration of each of
these substances varied among the strains tested and appeared to be
specific for each strain. An interesting variation was the low
concentration of pyruvate in the hemolymph of PR-snails. Only the
concentration of fumarate was consistently different (p{ 0.05) between
resistant and susceptible strains.
