Schistosomes undergo various morphological and metabolic
changes during their development, reflected in a finely tuned regulation
of protein and/or gene expression. The mechanisms involved in the control
of gene expression during the development of the parasite are not understood.
Two actin genes had been previously cloned and observed to be differentially
expressed during the maturation of the parasite. The SmAct gene contains
four putative cis-regulatory elements (TATA-, CCAAT-, E- and CArG-boxes).
Our objective was to investigate in greater detail the expression pattern
of two actin genes and verify if the binding of nuclear proteins to the
promoter elements of SmAct correlated with the expression profile observed.
We detected little variation in the expression of actin genes during the
first seven days of schistosomula culture in vitro. However, we observed
significantly higher levels of expression in males compared to female adults.
CArG and CCAAT elements bound to a greater extent and formed distinct complexes
with male in comparison to female nuclear extracts. In contrast, female
extracts bound weakly to the E-box probe while no binding was observed with
male extracts. Taken together these results describe cis-acting elements
that appear to be involved in sexually regulated gene expression in
Schistosoma mansoni
.
