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Biparental mitochondrial DNA inheritance in the parasitic trematode Schistosoma mansoni
L K Jannotti-Passos1, C P Souza, J C Parra
1Centro de Pesquisas Rene Rachou, Belo Horizonte, Minas Gerais, Brazil.
Abstract:
The maternal inheritance of mitochondrial DNA (mtDNA) in eukaryotic organisms occurs because of the selective destruction of paternal mtDNA molecules that may be present in the zygote. The elimination of sperm mtDNA is less efficient in interspecific crosses, and biparental inheritance of mtDNA has been observed in a variety of species. Because interspecific crosses are likely to be extremely rare in nature, parental inheritance of mtDNA has been deemed of little relevance to population genetics. The mtDNA of the parasitic trematode Schistosoma mansoni was examined for its utility in addressing epidemiological questions related to the transmission and spread of schistosomiasis. Prior to embarking on such experiments, we sought to confirm the mode of inheritance of this molecule using the highly polymorphic mtDNA minisatellite as a marker. In 3 separate crosses, mtDNA apparently identical to paternal DNA was observed in some individuals of the F2 and F3 generations. These observations thus suggest the intraspecific paternal inheritance of mtDNA across multiple generations in Schistosoma mansoni.
Insights
Mitochondrial DNA (mtDNA) is usually maternally inherited. However, this study found evidence of paternal mtDNA inheritance across generations in the parasitic Schistosoma mansoni worm, challenging previous assumptions.
Area of Science:
- Genetics
- Parasitology
- Evolutionary Biology
Background:
- Mitochondrial DNA (mtDNA) is typically maternally inherited in eukaryotes due to the destruction of paternal mtDNA in zygotes.
- Paternal mtDNA inheritance is rare and usually only observed in interspecific crosses, making it less relevant for population genetics.
- Schistosomiasis, a significant human parasitic disease, is caused by Schistosoma worms, and understanding their genetics is crucial for control.
Purpose of the Study:
- To investigate the mode of mitochondrial DNA (mtDNA) inheritance in the parasitic trematode Schistosoma mansoni.
- To determine if paternal mtDNA inheritance occurs within this species and its potential relevance to schistosomiasis epidemiology.
- To utilize the polymorphic mtDNA minisatellite as a marker for tracking inheritance patterns.
Main Methods:
- Examined the mitochondrial DNA (mtDNA) of Schistosoma mansoni.
- Conducted controlled crosses to observe inheritance patterns.
- Used highly polymorphic mtDNA minisatellite markers to identify paternal mtDNA contribution.
- Analyzed offspring from F2 and F3 generations.
Main Results:
- Observed mtDNA in some individuals of the F2 and F3 generations that was identical to paternal DNA.
- Demonstrated the presence of paternal mtDNA across multiple generations in Schistosoma mansoni.
- The efficiency of paternal mtDNA elimination appears to be lower in this species than previously assumed.
Conclusions:
- Intraspecific paternal inheritance of mtDNA occurs in Schistosoma mansoni across multiple generations.
- This finding has significant implications for population genetics and epidemiological studies of schistosomiasis.
- The study challenges the long-held belief of strict maternal mtDNA inheritance in parasitic organisms.