Trypanosoma brucei: inheritance of kinetoplast DNA maxicircles in a genetic cross and their segregation during vegetative growth.
The inheritance of maxicircle DNA was determined using a polymorphic EcoRI restriction site in the maxicircle variable region. In 11 hybrid progeny from a genetic cross of two stocks of Trypanosoma brucei, 7 progeny apparently inherited maxicircles uniparentally from either parent, in agreement with the results from previous studies, but in 4 progeny inheritance was biparental. Three subclones from 2 of these 4 progeny were made, and in these the maxicircles of only one parental type were detected. These data are considered in terms of a simple model whereby half the maxicircle genomes are inherited from each parent into progeny at meiosis with subsequent stochastic segregation at each mitotic division. This model generates a quantitative prediction as to the period of time required for fixation of inheritance to a uniparental pattern which provides a reasonable fit to the experimental data. These results provide an explanation as to why previous studies have shown that maxicircles are (apparently) inherited uniparentally: the kinetoplast is a unitary organelle inherited faithfully at cell division, but the maxicircles that it contains are best considered as a population that divides stochastically. Consideration of the model also explains why maxicircle populations are homogeneous.
Turner
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CM
Laboratory for Biochemical Parasitology, I.B.L.S., University of Glasgow, United Kingdom.
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Buchanan
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Tait
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D000818:Animals; D015139:Blotting, Southern; D002455:Cell Division / Q000235:genetics; D003433:Crosses, Genetic; D018105:DNA, Kinetoplast / Q000235:genetics*; D015246:Deoxyribonuclease EcoRI; D005819:Genetic Markers; D005838:Genotype; D007527:Isoenzymes / Q000032:analysis / Q000235:genetics; D008938:Mitosis; D010641:Phenotype; D012150:Polymorphism, Restriction Fragment Length; D015183:Restriction Mapping; D013269:Stochastic Processes; D014346:Trypanosoma brucei brucei / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development
D018105:DNA, Kinetoplast; D005819:Genetic Markers; D007527:Isoenzymes; D015246:Deoxyribonuclease EcoRI