Orbit/CLASP Is Required for Germline Cyst Formation through Its Developmental Control of Fusomes and Ring Canals in Drosophila Males
Figure 4
Conserved regions of Orbit are required for localization on fusomes and ring canals.
(A) Schematic representation of the conserved Orbit regions and localization of each domain on fusomes or ring canals. *HRII is localized inside ring canals, but is not restricted on the ring canal rims as shown for the wild-type Orbit. (B) The N-terminal region alone fused with GFP tag (green) is localized on fusomes stained with anti-spectrin antibody (red). Single-channel representation of N-Orbit fluorescence (middle). Single-channel representation of anti-spectrin immunostaining (right). The truncated protein can be additionally localized around each nucleus (arrowheads). (C) The N-terminal region fused with GFP tag (green) is not localized on ring canals recognized by anti-phospho-tyrosine antibody (red). Single-channel representation of N-Orbit fluorescence (middle) in an early-stage spermatocyte cyst. Single-channel representation of anti-phospho-tyrosine immunostaining (right). (D) In an early spermatocyte cyst at the S2a stage, the HRII region (red) is localized on fusomes (green). Single-channel representation of HRII-Orbit fluorescence (middle). Single-channel representation of anti-spectrin immunostaining (right). (E) The HRII region (red) is localized on fusome plugs formed in midbody between separated sister nuclei, but is not perfectly overlapped with ring canal rims stained with anti-phospho-tyrosine (green) in early spermatocyte cysts. Single-channel representation of RFP-HRII fluorescence (middle). Single-channel representation of anti-phospho-tyrosine immunostaining (right). DNA staining (blue). Scale bar = 10 µm.