Figures and data
Schematic of the nucleus magnocellularis inputs to the nucleus laminaris (nL) and topographical organisaton of the nL.
Bilateral nM inputs to dorsal and ventral dendrites of nL neurons create a neuronal map of auditory space. Coincidental ipsi– and contra-lateral inputs to a restricted subset of nL neurons, related to the interaural time difference (ITD) increase the probability of nL neuron firing an action potential (AP). The site of AP initiation and dendrite architecture of the nL neurons varies with characteristic frequency of the nL neuron
A-F, mafB expression at various HH stages indicated in the boxes above the panel. G-L FGF8 expression at the HH stages indicated in the boxes. M, N FGF8 and BrdU expression at HHst30 following BrdU application at st 16 (M) or st 19 (N) O FGF8 and BrdU expression at HH st 35 following BrdU application at HH stage 18.
A-D FGF8 expression at HH stage 30-39 indicated in the boxes above the panels. E-G FGF8 expression at HH stage 33 annotated to indicate the medial (Wm) Central (Wc) and Lateral (Wl) widths of the nL and the Lengths (L) of the nucleus. H schematic of that shown in E-G. I Graphs showing length to width ratios of the nL in Medial, Central and Lateral regions at HH stages 30, 33 and 36. J-L FGF8 expression at HH st 33 (J,L) related to Caspase-3 expression in the nL compared to a control area of the hindbrain (K) M potential models of lamina formation of the nL by spatially restricted cell death or cell movement.
A-I FGF8 (A,D,G), cadherin-22 (B, E, H) and cadherin-13 C, F, I) expression in the nM, nL and nA at HH stage 39, 32 and 30, as indicated in the left hand boxes. J-O Cadherin-2 (N-cadherin) expression in the hindbrain at rhombomere 5/6 at HH stages 17 (J) 21 (K) 23 (L) 26 (M) 30 (N) and 35 (O) P-R. ψ-catenin (P) and cadherin-2 (Q) expression in the nM and nL related to DAPI expression (R) at HH stage 36.
A-C FGFR1 (A) FGFR2 (B) and Sprouty-4 (C) expression at HH stage 34 D-F control in ovo electroporation of GFP at HH st 18 followed by expression of GFP (D) FGF8 (E) and cadherin-22 (F) at HH stage 30. G-I mFGF8-GFP in ovo co-electroporation at HH st 18 followed by GFP (G) and islet-1 (H) expression at rhombomere 8 at HH stage 30. I Quantitation of motor neuron number at r8 of mFGF8 electroporation compared to control. J-M FGF8 (J,L) and cadherin-22 expression (K,M) following mFGF8-GFP co-electroporation or on the control side of the hindbrain as indicated in the left-hand boxes. N Quantitation of FGF8 or cadherin-22 cells in the nL area at HH st 34 following mFGF expression compared to control. O Quantitation of FGF8 or cadherin-22 cells in the nL area at HH st34 following dn FGFR1 expression compared to control. P-R dnFGFR-1-GFP co-electroporation at HH st18 followed by analysis of GFP (P), FGF8 (Q) and cadherin-22 (R) expression at HH stage 34.
A-D r2 measures of lamina formation for each section of FGF8 in situ expression at HH stage 30 (A), st33 (B) st 36 (C) and st 39 (D) see materials and methods for details. E-L. FGF8 (E-H) and MafB (I-L) expression in hindbrain slices cultured in varying concentrations of exogenously added FGF8 indicated in the boxes above). M, N Box and whisker plots of r2 calculations of wildtype at different HH stages and in different concentrations of FGF8 in culture conditions (N)
A-F. GFP (A,D) and MafB (B,C,E, F) expression following in ovo electroporation of mFGF8. Analysis was at HH stage 30 in r3 (B, C) and r6 (E, F) for control side of the hindbrain (B, E) and experimental side (C, F). G-L mafB (G-I) and cadherin-22 (J-L) expression following in ovo electroporation of MafB. Internal control side of the hindbrain (G, J) and experimental sides (H,K, I, L) are shown. electroporation is marked by GFP (I, L) Isl-1 expression shows location of r5 motor nuclei and ganglia. M-R. dnMafB electroporation is detected by either GFP (O, R) or MafB experssion (M,N). P, Q shows its effect on Cadherin-22 expression.
A-F In ovo electroporation at stage 19 of either N-cadherin (A, B) or dominant negative N-cadherin (C-F) doxicycline was added at HH stage 30 and analysis was at HH stage 36. GFP (A, C) marks electroporated cells and axons. Analysis of nL/nM is shown by FGF8 expression (B, E), cadherin-22 (D) or cadherin-13 expression (F). Experimental or control sides of the hindbrain are shown as indicated in the boxes above.
(A) Diagram of simple square-based rod model for n units. Square-based rods have width X and height Y and are arranged on an orthorhombic lattice. There are a total of n units, with a, b and c integer units along the x, y and z axes respectively. (B) There are three different types of contact planes between adjacent units: x-y planes (red), x-z planes (green) and y-z planes (blue). The number and area of each type of plane are shown for internal planes (between units in the population of interest) and external planes (between the population of interest and surrounding media). (C) Outline of total adhesion energy calculation for a constant number of units (n) with uniform adhesion per unit area for internal contact planes and a reduced adhesion per unit area for external facing planes. (D) Dependency of the population maximum adhesion configuration (ac, bc, cc) on the individual unit structure. Solutions for the constrained maximum (Appendix 1) have critical values
FGF8 in situ hybridisation at HH stage 36 following BrdU application to embryos at HH stages 18 to 22, as indicated by the boxes above the panels A series of sections from individual embryos is shown from rostral to caudal (top panels to bottom panels) as indicated by the schema on the left hand side
FGF8 expression at HH stage 30 across the entire auditory hindbrain sections are numbered sequentially from rostral to caudal most and are indicated in the panels
FGF8 expression at HH stage 33 across the entire auditory hindbrain sections are numbered sequentially from rostral to caudal most and are indicated in the panels
FGF8 expression at HH stage 36 across the entire auditory hindbrain sections are numbered sequentially from rostral to caudal most and are indicated in the panels
FGF8 expression at HH stage 39 across the entire auditory hindbrain sections are numbered sequentially from rostral to caudal most and are indicated in the panels
ψ-catenin, N-cadherin, N-cadherin and FGF8 expression at HH stage 36 top panels Various sections across the auditory hindbrain are shown.
Bottom panels show a time series of expression in the auditory hindbrain at HH stage 30, stage 33 and stage 34
A-C. Dynamic adhesion model for nL formation.A. Schematic of a typical nL cell from the literature. nL cells show a characteristic bipolar morphology with dorsal and ventral dendrites. B. Schematic of the modelling of nL cells with a cell body and a dendrite modelled as springs capable of synamic displacement. C. Starting conditions of the dynamic model (see materials and methods) D. Time series ofthe dynamic model run with conditions of differential dorsal and ventral adhesion (bipolar adhesion conditions). E. Time series of the dynamic model run with conditions of equal adhesion potential between dorsal and ventral dendrite compartments.
Interactions between units on a triclinic lattice.
The numbers of each type of interaction are shown for a population of n units in a configuration with a units in the direction of a1, b units in the direction of a2 and c units in the direction of a3. A, B and C are adhesion energies associated with interactions that occur along the primitive lattice vector directions (a1, a2 and a3). R is the ratio of adhesion energies for external interactions at the edge of the population to internal interactions (within the population)
