A new look at the architecture and dynamics of the Hydra nerve net
- Department of Biology, Ludwig-Maximilians-University Munich, Germany
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg University, Germany
- Department of Zoology and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Austria
- Department of Biological Chemistry, University of California, United States
Figures
Figure 1 with 2 supplements
Distribution of pan-neuronal antibody (PNab)-stained nerve cells along the Hydra body axis.
The confocal images are maximum intensity projections of short stacks (10–15 µm) showing the ectoderm. (A) Upper body column including the hypostome and tentacles. (B) Lower body column including …
Figure 1—figure supplement 1
Structure of Hydra tissue imaged in transgenic polyps expressing DsRed2 in ectodermal epithelial cells and GFP in endodermal epithelial cells.
Nuclei are stained with DAPI. Images are maximum intensity projections of short stacks (3–5 µm). Ectodermal nuclei are magenta (DAPI+DsRed2). Endodermal nuclei are turquoise (DAPI+GFP). Blue DAPI …
Figure 1—figure supplement 2
Representative images of pan-neuronal antibody (PNab)-stained body column of a transgenic watermelon polyp (GFP in ectoderm, DsRed2 in endoderm) used to count epithelial cells and nerve cells.
The images are 250×250 µm2. The stack depth is 20 µm. Such images were used to count nerve cells and epithelial cells in the ectoderm. (A) PNab (red)-stained nerve cells (nerve cell nuclei stained …
Figure 2
Distribution of pan-neuronal antibody (PNab)-stained nerve cells in a cross-section of the body column.
(A) Schematic shows the position of imaged tissue. (B) Circular ring of tissue excised from the body column and viewed from above. The green line traces the position of the mesoglea separating …
Figure 3
Pan-neuronal antibody (PNab)-stained nerve cells in the hypostome (B, C, D), tentacle (E), and peduncle/basal disk (F).
(A) Schematic shows the orientation of the confocal images. The images are maximum intensity projections of short stacks (10–15 µm) through the ectoderm of the hypostome (B) and deeper in the tissue …
Figure 4
Segments of a ring of body column tissue excised perpendicular to the main body axis from Lifeact ecto (A) and Lifeact endo (B) polyps stained with pan-neuronal antibody (PNab) (red) and anti-GFP (green).
The confocal images are maximum intensity projections of short stacks (20 µm) down the body column. (A) Lifeact ecto polyp. In the ectoderm small red spots (neurites) and green spots (muscle …
Figure 5
Lifeact ecto (A and B) and Lifeact endo (C and D) polyps stained with pan-neuronal antibody (PNab).
Confocal images are maximum intensity projections of image stacks in the ectoderm and endoderm. Small schematics indicate position of the images. (A) Lifeact ecto polyp showing the base of a …
Figure 6
Nerve cell to epithelial cell ratio along the body column of Hydra.
Transgenic watermelon and inverse watermelon polyps were stained with pan-neuronal antibody (PNab) to identify nerve cells and with DAPI to identify nuclei. Confocal stacks were taken through the …
Figure 7
Transgenic nGreen polyp stained with anti-GFP (green) and pan-neuronal antibody (PNab) (red).
Confocal images of the ectoderm in the body column showing two GFP-labeled nerve cells overlapping the PNab-stained nerve net. (A) Anti-GFP, (B) PNab, and (C) overlay of anti-GFP (green) and PNab …
Figure 8
Transgenic nGreen polyp stained with pan-neuronal antibody (PNab) (red) and anti-GFP (green).
(A–C) Maximum intensity projection confocal image stack of a GFP-stained nerve cell tightly associated with a PNab (red)-stained neurite from another cell. (D–F) Single optical section from the …
Figure 9
Position and structure of neurite bundles in the mid-body column in transmission electron microscopy (TEM) cross-sections.
To facilitate identification, neurites are overlaid in orange-blue-purple, the nerve cell body in red, muscle processes in green, and the mesoglea in yellow. (A) Low magnification of the ectoderm. A …
Figure 10 with 1 supplement
3D reconstruction of 2000 serial sections obtained by serial block face scanning electron microscopy (SEM) in the ectoderm of the body column.
(A) Two nerve cell bodies and their neurites are colored green and purple (nuclei are highlighted in blue). Three additional neurites from nerve cells outside the imaged block are colored yellow, …
Figure 10—figure supplement 1
3D interactive model of the serial block face scanning electron microscopy (SEM) reconstruction shown in Figure 10.
The interactive 3D model can be accessed by clicking into the figure and dragging the image with the left mouse button pressed (Adobe Reader Version 7 or higher required). Scale bar: 20 µm.
Figure 11
Nerve cell composition of neurite bundles.
Transgenic Hym176B animal stained with anti-GFP and pan-neuronal antibody (PNab). (A) Overview of hypostome (white arrow), tentacles, and upper body column showing transgenic Hym176B nerve cells …
Figure 12
Gap junctions and innexins.
(A and B) Transmission electron microscopy (TEM) images of longitudinal sections in the mid-body column of the ectoderm show neurite bundles running along muscle processes. Gap junctions connecting …
Figure 13
Differentiation of migrating nerve cell precursors in AEP (top)/nGreen (bottom) grafts stained with pan-neuronal antibody (PNab).
(A) Schematic of AEP/nGreen graft. (B and C) Two images of differentiating nerve cell precursors (nGreen) on day 2 after grafting. Nerve net stained with PNab (red). White arrows mark association of …
Figure 14
Schematic diagram of nerve net growth by lateral association of newly differentiated nerve cells (blue) with the pre-existing nerve net (green and red).
Upper images: the base of tentacles; lower images: the middle of the body column. The images are approximately to scale and show changes associated with tissue growth. (A) Nerve net at t0. (B) Nerve …
Figure 15
Sequence alignment of the intracellular domains of classic cadherin proteins from H. vulgaris (strain 105), H. oligactis, and H. viridissima.
The p120/delta-catenin and the beta-catenin binding domains are highly conserved in all three species and anchor the alignment. The sequence between these two conserved domains is quite variable …
