Symmetric and asymmetric mitotic segregation patterns influence Wolbachia distribution in host somatic tissue

Abstract

Wolbachia are maternally inherited bacterial endosymbionts that occupy many but not all tissues of adult insects. During the initial mitotic divisions in Drosophila embryogenesis, Wolbachia exhibit a symmetric pattern of segregation. Wolbachia undergo microtubule-dependent and cell-cycle-regulated movement between centrosomes. Symmetric segregation occurs during late anaphase when Wolbachia cluster around duplicated and separating centrosomes. This centrosome association is microtubule-dependent and promotes an even Wolbachia distribution throughout the host embryo. By contrast, during the later embryonic and larval neuroblast divisions, Wolbachia segregate asymmetrically with the apical self-renewing neuroblast. During these polarized asymmetric neuroblast divisions, Wolbachia colocalize with the apical centrosome and apically localized Par complex. This localization depends on microtubules, but not the cortical actin-based cytoskeleton. We also found that Wolbachia concentrate in specific regions of the adult brain, which might be a direct consequence of the asymmetric Wolbachia segregation in the earlier neuroblast divisions. Finally, we demonstrate that the fidelity of asymmetric segregation to the self-renewing neuroblast is lower in the virulent Popcorn strain of Wolbachia.

A feedback loop betweenWolbachiaand theDrosophila gurkenmRNP complex influencesWolbachiatiter

“…Examination of the egg chambers using TRITC epifluorescence settings triggers release of Syto-82 from the clouds into the cytoplasm. This gives rise to a uniform background in uninfected egg chambers, whereas infected egg chambers display a specific, punctate staining pattern that is consistent with Wolbachia size, motility and distribution as indicated by other studies (Ferree et al, 2005;Frydman et al, 2006;Serbus and Sullivan, 2007;Albertson et al, 2009;Casper-Lindley et al, 2011) (supplementary material Movies 1-3).…”

“…Dissected ovaries were incubated for 7 minutes in Syto-82 (Invitrogen) (Albertson et al, 2009) diluted into Shields and Sang M3 tissue culture medium (Sigma) at 1:250. The tissue was mounted on coverslips under 700 W halocarbon oil and left to equilibrate for a minimum of 1 hour.…”

Evolutionarily conserved Wolbachia -encoded factors control pattern of stem-cell niche tropism in Drosophila ovaries and favor infection

“…Several studies have described Wolbachia preferential infection of different tissues, host cells, and subcellular locations in the Drosophila genus, including adult brain, embryonic neuroblasts, specific regions of the oocyte during oogenesis, and posterior or anterior areas of the early embryo (9,(28)(29)(30). Considering Wolbachia's transmission across generations, a site in the host of particular interest is the germplasm, which is a highly specialized, maternally synthesized cytoplasm that is deposited in the posterior pole of the egg and induces the formation of the germ line in the embryo (ref .…”

Reliance of Wolbachia on High Rates of Host Proteolysis Revealed by a Genome-Wide RNAi Screen of Drosophila Cells

“…The cell line was created from primary embryonic cultures of Drosophila melanogaster infected with wMel Wolbachia strain (Serbus et al 2012). Wolbachia is stably maintained in these cultures and exhibits a close association with microtubules as found in Drosophila somatic and germline tissues (Kose and Karr 1995;Albertson et al 2009). The cell line expresses a transgene encoding the GFP-tagged gene Jupiter, which encodes a microtubule-associated protein that labels microtubules and facilitates high-throughput, cell-based screening approaches (Karpova et al 2006).…”