Bioelectrical and cytoskeletal patterns correlate with altered axial polarity in the follicular epithelium of the Drosophila mutant gurken

摘要

Comparison of wt and follicles. The dorsal side of wt S10B is defined by a thicker, columnar follicular epithelium (FE) and by an anterodorsal position of the oocyte nucleus (ON, red circle; cFC, centripetal follicle cells; mFC, mainbody follicle cells; pFC, posterior follicle cells). S10B lacks dorsoventral (d-v) polarity and is characterised by a uniform cuboidal, ventralised FE covering the oocyte (Ooc). While, in wt S10B, border cells (BC) are located close to the ON, in S10B, disrupted body-axis formation leads to undefined positioning of BC amongst the nurse cells (NC). The ON is often located at the posterior end of the Ooc in a typical protrusion. Transheterozygous combinations of alleles HF48 and 2B6 result in ventralised follicles of all vitellogenic stages (S8–14; bright-field image). In S12–14, wt-typical dorsal respiratory appendages are missing and a second micropylar structure appears at the posterior end. To visualise basal microfilaments (bMF) and microtubules (MT) in the FE, tangential optical sections using structured-illumination microscopy (SIM; focal plane: red line) were used. For analysis of V - and pH -patterns, median optical sections (SIM; focal plane: turquoise line) were used. Quantification of transversal ( ) and anteroposterior (a-p; ) gradients of V and pH , respectively, in the FE of S10B. Example of a follicle (SIM) where DiBAC-fluorescence intensities of FE (area marked in yellow) and FE (white) as well as of aFE (red) and pFE (blue) were measured using ImageJ (“mean grey value”). In wt follicles, the d-v axis was identified via the anterodorsal position of the ON, and the fluorescence intensities of the dorsal and ventral FE were quantified accordingly