Determination of Wolbachia genome size by pulsed-field gel electrophoresis.
Genome sizes of six different Wolbachia strains from insect and nematode hosts have been determined by pulsed-field gel electrophoresis of purified DNA both before and after digestion with rare-cutting restriction endonucleases. Enzymes SmaI, ApaI, AscI, and FseI cleaved the studied Wolbachia strains at a small number of sites and were used for the determination of the genome sizes of wMelPop, wMel, and wMelCS (each 1.36 Mb), wRi (1.66 Mb), wBma (1.1 Mb), and wDim (0.95 Mb). The Wolbachia genomes studied were all much smaller than the genomes of free-living bacteria such as Escherichia coli (4.7 Mb), as is typical for obligate intracellular bacteria. There was considerable genome size variability among Wolbachia strains, especially between the more parasitic A group Wolbachia infections of insects and the mutualistic C and D group infections of nematodes. The studies described here found no evidence for extrachromosomal plasmid DNA in any of the strains examined. They also indicated that the Wolbachia genome is circular.
Section of Vector Biology, Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
L V
LV
Sun
J M
JM
Foster
G
G
Tzertzinis
M
M
Ono
C
C
Bandi
B E
BE
Slatko
S L
SL
O'Neill
D002876:Chromosomes, Bacterial; D004269:DNA, Bacterial / Q000032:analysis; D016521:Electrophoresis, Gel, Pulsed-Field; D016680:Genome, Bacterial; D020577:Wolbachia / Q000235:genetics* / Q000302:isolation & purification
D004269:DNA, Bacterial