Schistosoma japonicum: excretory-secretory products of the eggs during miracidial development
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1Department of Parasitology, National Institute of Health, Tokyo, Japan.
Abstract:
The release pattern of excretory-secretory (E-S) products of Schistosoma japonicum eggs was investigated using eggs cultured in a chemically defined medium (MEMSE-J) for 16 days. The amount of protein released in culture supernatants was greater in 0- to 4-day and 12- to 16-day cultures than in 4- to 12-day cultures. The protein composition of E-S products and soluble extracts of newly laid eggs (N-SEA) and in vitro matured eggs (M-SEA) was analyzed by SDS-PAGE. Silver staining patterns of N-SEA and M-SEA were found to be similar except for the band at approximately 66 kDa, which appeared in highest concentrations in N-SEA. Western blot analysis with human infected sera showed antibody recognition of a 140- to 160-kDa antigen present in E-S products from mature eggs, while E-S products from immature eggs were unreactive. When either [35S]methionine or [3H]glucosamine was added to the culture medium, newly synthesized proteins or glycoproteins of the SEA and E-S products were labeled. Incorporation of both isotopes into SEA appears to correlate with developmental activity of the eggs. In contrast, release of E-S proteins and glycoproteins is more apparent as the miracidium matures. These results suggested that the source of E-S products from immature eggs is likely to be the collapsing vitelline cells and that of E-S products from mature eggs to be mainly miracidial secretions.
Insights
Schistosoma japonicum egg excretory-secretory (E-S) products differ between immature and mature stages. Mature eggs release more E-S proteins and glycoproteins, likely from miracidial secretions, unlike immature eggs where vitelline cells contribute.
Area of Science:
- Parasitology
- Molecular Biology
- Biochemistry
Background:
- Schistosoma japonicum eggs release excretory-secretory (E-S) products.
- Understanding the composition and release patterns of these products is crucial for disease research.
Purpose of the Study:
- To investigate the release pattern and protein composition of Schistosoma japonicum egg E-S products.
- To differentiate the sources of E-S products from immature versus mature eggs.
Main Methods:
- Eggs were cultured in a chemically defined medium (MEMSE-J) for 16 days.
- Protein analysis of E-S products and egg extracts using SDS-PAGE and Western blot.
- Radioactive labeling with [35S]methionine and [3H]glucosamine to track newly synthesized proteins and glycoproteins.
Main Results:
- Higher protein release observed in early (0-4 days) and late (12-16 days) culture stages.
- SDS-PAGE revealed similar protein profiles for newly laid egg extracts (N-SEA) and in vitro matured egg extracts (M-SEA), with a notable 66 kDa band in N-SEA.
- Western blot identified a 140- to 160-kDa antigen in E-S products from mature eggs, reactive with human infected sera.
- Radioisotope incorporation indicated correlation between SEA synthesis and egg developmental activity, with E-S product release increasing with miracidial maturation.
Conclusions:
- E-S products from immature Schistosoma japonicum eggs likely originate from collapsing vitelline cells.
- E-S products from mature eggs are primarily derived from miracidial secretions.
- The observed differences in E-S product release and composition reflect egg developmental stages.