Intramitochondrial Location and Dynamics of Crithidia fasciculata Kinetoplast Minicircle Replication Intermediates

Kinetoplast DNA, the mitochondrial DNA of Crithidia fasciculata, is organized into a network containing 5,000 topologically interlocked minicircles. This network, situated within the mitochondrial matrix, is condensed into a disk-shaped structure located near the basal body of the flagellum. Fluorescence in situ hybridization revealed that before their replication, minicircles are released vectorially from the network face nearest the flagellum. Replication initiates in the zone between the flagellar face of the disk and the mitochondrial membrane (we term this region the kinetoflagellar zone [KFZ]). The replicating minicircles then move to two antipodal sites that flank the disk-shaped network. In later stages of replication, the number of free minicircles increases, accumulating transiently in the KFZ. The final replication events, including primer removal, repair of many of the gaps, and reattachment of the progeny minicircles to the network periphery, are thought to take place within the antipodal sites.

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Retrieval of Four Adaptive Lineages in Duiker Antelope: Evidence from Mitochondrial DNA Sequences and Fluorescence in Situ Hybridization

Molecular Phylogenetics and Evolution ◽

10.1006/mpev.2001.0962 ◽

2001 ◽

Vol 20 (3) ◽

pp. 409-425 ◽

Cited By ~ 17

Author(s):

Bettine Jansen van Vuuren ◽

Terence J. Robinson

Keyword(s):

Mitochondrial Dna ◽

In Situ Hybridization ◽

Fluorescence In Situ Hybridization ◽

Dna Sequences

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Kinetoplast DNA replication: mechanistic differences between Trypanosoma brucei and Crithidia fasciculata.

The Journal of Cell Biology ◽

10.1083/jcb.126.3.631 ◽

1994 ◽

Vol 126 (3) ◽

pp. 631-639 ◽

Cited By ~ 32

Author(s):

M L Ferguson ◽

A F Torri ◽

D Pérez-Morga ◽

D C Ward ◽

P T Englund

Keyword(s):

Electron Microscopy ◽

Mitochondrial Dna ◽

Dna Replication ◽

Trypanosoma Brucei ◽

Protein Complexes ◽

Kinetoplast Dna ◽

Relative Movement ◽

Crithidia Fasciculata ◽

Trypanosomatid Parasites

Kinetoplast DNA, the mitochondrial DNA of trypanosomatid parasites, is a network containing several thousand minicircles and a few dozen maxicircles. We compared kinetoplast DNA replication in Trypanosoma brucei and Crithidia fasciculata using fluorescence in situ hybridization and electron microscopy of isolated networks. One difference is in the location of maxicircles in situ. In C. fasciculata, maxicircles are concentrated in discrete foci embedded in the kinetoplast disk; during replication the foci increase in number but remain scattered throughout the disk. In contrast, T. brucei maxicircles generally fill the entire disk. Unlike those in C. fasciculata, T. brucei maxicircles become highly concentrated in the central region of the kinetoplast after replication; then during segregation they redistribute throughout the daughter kinetoplasts. T. brucei and C. fasciculata also differ in the pattern of attachment of newly synthesized minicircles to the network. In C. fasciculata it was known that minicircles are attached at two antipodal sites but subsequently are found uniformly distributed around the network periphery, possibly due to a relative movement of the kinetoplast disk and two protein complexes responsible for minicircle synthesis and attachment. In T. brucei, minicircles appear to be attached at two antipodal sites but then remain concentrated in these two regions. Therefore, the relative movement of the kinetoplast and the two protein complexes may not occur in T. brucei.

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