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Genomic instability in Schistosoma mansoni
1Institute for Genetics, Genetic Parasitology and Center for Biological and Medical Research, Heinrich-Heine-University, Düsseldorf, Germany. greveld@uni-duesseldorf.de
Molecular and Biochemical Parasitology
|July 21, 1999
Summary
Schistosome W chromosomes contain repetitive elements W1 and W2. Genomic instability, not polymorphic Z chromosomes, explains their variable occurrence in Schistosoma mansoni populations.
Area of Science:
- Genetics
- Parasitology
- Molecular Biology
Background:
- Schistosomes exhibit ZW sex determination in females and ZZ in males.
- Repetitive elements W1 and W2 were initially identified as female-specific sequences in Schistosoma mansoni.
Purpose of the Study:
- To investigate the occurrence and distribution of W1 and W2 elements in Schistosoma mansoni.
- To clarify the genetic basis for the observed variations in W1 and W2 element presence.
Main Methods:
- Polymerase Chain Reaction (PCR) and Southern-blot experiments were utilized.
- Analysis was performed on DNA from clonal populations, individual clones, and progeny from crossing experiments.
Main Results:
- Contrary to previous findings, W1 and W2 elements were found to occur gender-independently across various strains.
- Significant inter- and intra-clonal variations in W1 and W2 element distribution were observed, even within genetically identical clones.
- The data did not support the hypothesis of polymorphic Z chromosomes.
Conclusions:
- Genomic instability, likely due to aberrant DNA recombination at meiotic and mitotic levels, is proposed as the cause of W1 and W2 element variation.
- This genomic instability represents a novel mechanism for generating genetic variability in schistosomes.