Actin and intermediate-sized filaments of the spines and cytoskeleton of Schistosoma mansoni

Abstract

The organization of spines and filaments in whole worms and cytoskeletal fractions of adult Schistosoma mansoni was investigated. The ultrastructure of the spine revealed a closely packed filamentous organization of 3.5- to 5.6-nm elements and electron-lucent areas. Spines were surrounded at the base by electron-dense bodies and membrane invaginations, and covered at the tip by the syncytial surface membrane. Filaments, 7.5-11.1 nm in diameter, were closely associated with the base of the spines, between muscles, near mitochondria or nuclei, and in spaces of the subtegument. Cytoskeletal fractions prepared by homogenizing adults in Tris-HCl buffer, containing 0.6 M KCl and 1.0% Triton X-100, represented 19%-25% and 32%-38% of wet weight of males and females, respectively. The fractions contained nuclei, spines, 8 to 11 nm filaments, myofibrils, and granules. Vitellaria and egg shells were abundant in fractions from females. Six polypeptides with estimated molecular weights of 130, 96, 84, 78, 74 and 43 kdaltons were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis as the major components of the cytoskeleton. Monoclonal antibody to chicken actin (MAA) was localized predominantly in surface spines and tubercles of adult schistosomes by the indirect immunofluorescence test, while immune serum from infected mice reacted less specifically with the tegument. A 43-kdalton polypeptide with electrophoretic mobility identical to that of vertebrate actin, identified in cytoskeletal and tegumental fractions of adult worms, reacted positively with MAA on immunoblotting.(ABSTRACT TRUNCATED AT 250 WORDS)

The cytoskeleton and motor proteins of human schistosomes and their roles in surface maintenance and host–parasite interactions

“…Actin appears to be present, (47) albeit not abundant and information on its subcellular distribution is scant. (47,53,55) Microtubules appear not to be present in the distal cytoplasm, occurring in the cytoplasmic bridges. Tubulin does not appear to co-localize with dynein light chains, which abound in the distal cytoplasm.…”

“…This microtubular array undoubtedly is used for anterograde transport through the cytoplasmic bridges, as disruption of the microtubular cytoskeleton of schistosomes also disrupts surface expression of major components (51) including some carbohydrates. (52) Actin is present in the musculature of schistosomes as well as in the tegument, (53)(54)(55) where in S. mansoni, it occurs predominantly in the spines and tubercles. (35,53,56) Actin also appears after tegument damage.…”

“…(52) Actin is present in the musculature of schistosomes as well as in the tegument, (53)(54)(55) where in S. mansoni, it occurs predominantly in the spines and tubercles. (35,53,56) Actin also appears after tegument damage. (55) Within the spines, actin is aligned in crystalline arrays.…”

Proteomic Analysis of Schistosoma japonicum Schistosomulum Proteins that are Differentially Expressed Among Hosts Differing in Their Susceptibility to the Infection

“…Actin belongs to a highly conserved family of proteins found in all eukaryotes and is a critical component of the muscle system (45,46). It was shown to be present on the surface of schistosomula, in the muscle, tegumental tubercles and spines of male and female adult worms (47)(48)(49)(50). The movement of schistosomes is accomplished through welldeveloped muscular arrangements that are mainly facilitated by tubulin and actin molecules (51).…”

Biophysical studies of the schistosome surface and their relevance to its properties under immune and drug attack

“…As discussed above, immobile proteins and lipids might be restrained by some form of cytoskeleton. Filamentous actin has been identified in spines and in subtegumental muscles by staining with rhodamine-labelled phalloidin or by anti-actin antibodies (Cohen et al 1982, Abbas & Cain 1987. By cooling worms labelled with CI8F1 it was observed that the highly folded and tubercle-rich membrane segregated to form a much smoother surface (Figure 5).…”