STRUCTURAL ORGANIZATION AND DISTRIBUTION OF SYMBIOTIC BACTERIA WOLBACHIA IN EARLY
EMBRYOS AND OVARIES OF DROSOPHILA MELANOGASTER AND D. SIMULANS
N. V. Dudkina, 1, 2 D. A. Voronin, 1 E. V. Kiseleva 1 *
1 Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk, Russia
and 2 Novosibirsk State University, Russia;
* e-mail: elka@bionet.nsc.ru
Electron microscopic and morphometric analyses of Wolbachia distribution in early embryos of
Drosophila flies have demonstrated that the number of bacteria in the embryo remains constant from fertilization to blastoderm,
and that afterwards the symbionts could be observed only in the polar cells. Each bacterium has a three-layer envelope, makes contacts
with microtubules and moves through the cytoplasm following the actively dividing nuclei. It has been found for the first time that
Wolbachia could produce secretory vacuoles in the cytoplasm of early embryos. The relative volume of Wolbachia was five
times as much in the embryos of Drosophila simulans as in thouse of D. melanogaster (Canton S), while the survival rate of
D. simulans was half as much as that of D. melanogaster. It was shown that Wolbachia could form spore-like
structures in D. simulans embryous. Ultrastructural investigations of Drosophila ovaries suggest that the bacteria may be
present in all ovariol cells, including the oocyte, within whose cytoplasm they are delivered to the host. The highest number of symbionts
was observed in germarium cells. In ovariol cells, the bacteria gradually decrease in number as ooge-nesis progresses. It has been
determined for the first time that the symbionts are located closely to membranes of rough endoplasmatic reticulum in follicular and nurse
cells of D. melanogaster. The data obtained suggest that Wolbachia may be involved in the regulation of oocyte maturation.
Key words: Wolbachia, Drosophila, embryogenesis, oogenesis, symbionts, electron microscopy
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