Dj. Oldenburg et Aj. Bendich, THE STRUCTURE OF MITOCHONDRIAL-DNA FROM THE LIVERWORT, MARCHANTIA-POLYMORPHA, Journal of Molecular Biology, 276(4), 1998, pp. 745-758
The structure of mitochondrial DNA (mtDNA) from cultured cells of the
liverwort, Marchantia polymorpha, was analyzed by pulsed-field gel ele
ctrophoresis (PFGE) and moving pictures of the fluorescently labeled m
olecules. Previous electron microscopic analysis with this liverwort r
evealed a unique property among land plants: mtDNA circles of only one
size, that of the 186 kb genome, with no subgenomic circles. Most of
the mtDNA was immobile in PFGE and contained complex structures, large
r than the genome size with a bright fluorescent node and multiple att
ached fibers. The mobile mtDNA was mostly linear molecules in monomeri
c to pentameric lengths of the unit genome that increased following mu
ng bean nuclease digestion, with a corresponding decrease in the immob
ile fraction. From 0 to 5% of the mtDNA was found as circular molecule
s the size of the genome and its oligomers; no subgenome-sized circles
were present. Radiolabeling revealed that mtDNA synthesis began soon
after transfer of cells to fresh medium and most newly replicated mtDN
A was immobile; the circular form of the genome was not rapidly labele
d. (C) 1998 Academic Press Limited.