THE CONFIGURATION OF DNA-REPLICATION SITES WITHIN THE TRYPANOSOMA-BRUCEI KINETOPLAST

Citation
Dr. Robinson et K. Gull, THE CONFIGURATION OF DNA-REPLICATION SITES WITHIN THE TRYPANOSOMA-BRUCEI KINETOPLAST, The Journal of cell biology, 126(3), 1994, pp. 641-648
Citations number
22
Categorie Soggetti
Cytology & Histology
Journal title
ISSN journal
00219525
Volume
126
Issue
3
Year of publication
1994
Pages
641 - 648
Database
ISI
SICI code
0021-9525(1994)126:3<641:TCODSW>2.0.ZU;2-M
Abstract
The kinetoplast is a concatenated network of circular DNA molecules fo und in the mitochondrion of many trypanosomes. This mass of DNA is rep licated in a discrete ''S'' phase in the cell cycle. We have tracked t he incorporation of the thymidine analogue 5-bromodeoxyuridine into ne wly replicated DNA by immunofluorescence and novel immunogold labeling procedures. This has allowed the detection of particular sites of rep licated DNA in the replicating and segregating kinetoplast. These stud ies provide a new method for observing kinetoplast DNA (kDNA) replicat ion patterns at high resolution. The techniques reveal that initially the pattern of replicated DNA is antipodal and can be detected both on isolated complexes and in replicating kDNA in vivo. In Trypanosoma br ucei the opposing edges of replicating kDNA never extend around the co mplete circumference of the network, as seen in other kinetoplastids. Furthermore, crescent-shaped labeling patterns are formed which give w ay to labeling of most of the replicating kDNA except the characterist ic midzone. The configuration of these sites of replicated DNA molecul es is different to previous studies on organisms such as Crithidia fas ciculata, suggesting differences in the timing of replication of mini and maxicircles and/or organization of the replicative apparatus in th e kinetoplast of the African trypanosome.