Schistosoma mansoni: the sex ratios of worms in animals infected with cercariae from three species of Biomphalaria

Abstract

The ratios of male to female worms of Schistosoma mansoni were determined in mice infected with cercariae from LE, SJ and AL strains shed by mollusc hosts of the parasite in Brazil. The sex ratios of worms in the animals were similar with cercariae from Biomphialaria glabrata and B. tenagophila varying from 1.1:1 to 1.6:1 with LE and AL strains and 1:1.1 with SJ. In the animals infected with cercariae from B. straminea the ratio of male to female worms was similar to those obtained using cercariae shed from the other two species of molluscs, 1.5:1 with LE strain. Inoculations by AL and SJ cercariae resulted in sex ratios of 3.1:1 and 6:1 respectively. The normal sex ratios of worms established in Brazil in animals inoculated with cercariae from B. glabrata and B. tenagophila is from 1:1 to 2:1. The higher number of male worms that developed from cercariae of the AL and SJ strains obtained from B. straminea indicate a lower compatibility of the snail concerning these strains of S. mansoni.

Mass Spectrometric Analysis of the Schistosoma mansoni Tegumental Sub-proteome

“…It has been demonstrated that the sex ratio of S. mansoni is male biased, displaying male:female ratios of 1.1:1 to even 6:1 in infected mice, depending on the strain of the intermediate host. 35 Furthermore, male adults have a greater biomass than females, which attributes to the male bias even more. However, the effect of this overrepresentation of proteins derived from male worms has to be considered minor, since a recent study comparing the proteomes of male and female S. japonicum parasites shows that adult female worms express relatively low number (2.46%) of female-specific proteins.…”

“…It has to be noted that proteins from male adult worms are probably overrepresented in our samples. It has been demonstrated that the sex ratio of S. mansoni is male biased, displaying male:female ratios of 1.1:1 to even 6:1 in infected mice, depending on the strain of the intermediate host …”

A comparative parasitologic study on Biomphalaria glabrata snail and C3H/He mice infected with human and murine isolates of Schistosoma mansoni derived from Sumidouro, Rio de Janeiro, Brazil

“…The normal adult worm sex-ratio in Brazil is male biased (Souza et al 1996). The origin of this bias is not well understood.…”

A quantitative view of the transcriptome of Schistosoma mansoni adult-worms using SAGE

“…The frequency of this tag strongly suggests that this is the most abundant mRNA species found in adult worms. This abundance is highly significant, especially if we consider the larger biomass of male worms as well as the male bias found in the sex ratio of S. mansoni infections [32]. Indeed, among the top 5% most abundant transcripts of adult worms, we can find other eggshell-related genes such as P40 (146 th most abundant transcript, with 56 tags), P19 (202 nd with 42 tags) and P48 (356 th with 26 tags), which advocates their importance in the early-stages of eggshell formation.…”