Article Figures & Data
Figures
- Fig. 1.
Genetic strategy. A, Genomic organization of the mOR37 locus, redrawn from Strotmann et al. (1999). The coding regions are indicated by boxes(not drawn to scale), and their transcriptional orientation is indicated by arrows. The distance between the coding regions is given in kilobases. The asterisk indicates that mOR37D is a pseudogene. B–D, Targeted mutagenesis of mOR37 genes. B,mOR37A. a, Wild-typemOR37A locus; the coding region is represented by ared box. Restriction sites are indicated forEcoRI (E) and SacI (S). b,mOR37A-IRES-taulacZ-LTNL targeting vector. The white box labeled irepresents the IRES sequence, the blue box represents the coding sequence of taulacZ, and the yellow box represents theneo-selectable marker LTNL (not drawn to scale) flanked by loxP sites (indicated by black triangles). c, mOR37A locus after homologous recombination. d,mOR37A-IRES-taulacZ(A-lacZ) mutation after Cre-mediated excision of the neo-cassette, which leaves a single loxP site behind. The 5′ and 3′ external probes used to detect, respectively, homologous recombination and Crerecombination, are indicated as horizontal bars on theleft and right, respectively.e,mOR37A-IRES-tauGFP(A-GFP) mutation, afterCre-recombination. C,mOR37B. a, Wild-typemOR37B locus; the coding region is indicated by anorange box. Restriction sites for EcoRI (E), BamHI (B), and KpnI (K) are indicated. b,mOR37B-IRES-taulacZ-LNLtargeting vector. The yellow box represents theneo-selectable marker LNL (not drawn to scale) flanked by loxP sites (indicated by black triangles). c,mOR37B-IRES-taulacZ(B-lacZ) mutation afterCre-recombination. D,mOR37C. a, Wild-typemOR37C locus; the coding region is indicated by apink box. Restriction sites for EcoRI (E) and SpeI (Sp) are indicated.b,mOR37C-IRES-taulacZ-LTNLtargeting vector. c,mOR37C-IRES-taulacZ(C-lacZ) mutation, afterCre-recombination. d,mOR37C-IRES-tauGFP(C-GFP) mutation, afterCre-recombination.
- Fig. 2.
Patterns of mOR37-expressing OSNs in the nasal cavity. a, Whole-mount view of the right half-head from an A-lacZ mouse stained with X-gal. The nasal septum was removed, allowing a view onto the medial aspect of the turbinates. Blue cells are clustered in a patch in the central region of the turbinates (anterior is to theleft, and dorsal is to the top).b, Whole-mount preparation of a B-lacZmouse stained with X-gal. c, Whole-mount preparation of a C-lacZ mouse stained with X-gal. d, Whole-mount in situ hybridization using a probe specific for mOR37B. Reactive cells are clustered in the same small area of epithelium as those cells expressing the corresponding mutant allele in B-lacZ mice (compare withb). e, f, Adjacent coronal sections through the nasal cavity from a heterozygousB-lacZ mouse stained with X-gal (e) or subjected to in situhybridization with a probe specific for mOR37B(f). The pattern of cells labeled by either X-gal staining or in situ hybridization is superimposable. Reactive cells are clustered on the tips of endoturbinates II and III and on ectoturbinate 3. Scale bars: e, f, 200 μm.
- Fig. 3.
Laminar patterning ofmOR37-expressing OSNs. a,c, d, f, g,i, Cross-sections of the olfactory epithelium.b, e, h, Graphic representations of the numbers of reactive cells in different laminae; data were collected from randomly selected and informative sections of four mice each. a, A-lacZ mouse stained with X-gal. Reactive cells are located within the middle layer of the epithelium. b, Laminar distribution of cell bodies reactive with X-gal in A-lacZ mice (blue bars) and with a specific probe in wild-type mice (pink bars). c, In situ hybridization of wild-type mouse with a probe specific formOR37A. d, B-lacZ mouse stained with X-gal. Reactive cells are closer to the luminal surface than A-lacZ cells (see a). e, Laminar distribution of cell bodies reactive with X-gal inB-lacZ mice (blue bars) and with a specific probe in wild-type mice (pink bars).f, In situ hybridization of wild-type mouse with a probe specific for mOR37B.g, C-lacZ mouse stained with X-gal. Reactive cells are located very close to the luminal surface.h, Laminar distribution of neurons reactive with X-gal in C-lacZ mice (blue bars) and with a specific probe in wild-type mice (pink bars).i, In situ hybridization of wild-type mouse with a probe specific for mOR37C. Cells are located in an apical cellular layer, similar toC-lacZ-expressing neurons. Scale bars: (ind) a, d, g, 20 μm; (in f) c,f, i, 20 μm.
- Fig. 4.
MOR37 gene- and allele-specific expression patterns. Cross-sections through the olfactory epithelium of double- or compound-heterozygous mice. The genotype is indicated in thetop right of each panel. GFP-expressing cells are green fluorescent, lacZ-expressing cells are red fluorescent; cells coexpressing GFP and lacZ are yellow in double exposure. a, OMP-GFP × B-lacZmouse. All neurons expressing B-lacZ coexpress GFP and are yellow. b, A-GFP× B-lacZ mouse. Two distinct neuronal populations are visible, either green fluorescent (A-GFP) or red fluorescent (B-lacZ). No double-stained neuron is detectable. c, B-lacZ ×C-GFP mouse. No cells are both red and green fluorescent. Note that both populations are located rather apically within the epithelium. d, A-lacZ ×C-GFP mouse. No double-stained neurons are detectable. Both populations are located in different horizontal layers of the epithelium. e, A-lacZ ×A-GFP mouse. The mOR37A gene is strictly subject to monoallelic expression. Two differentially stained neuronal populations are detectable, and no double-stained cells are found. Note the location of cell bodies preferentially in the middle cellular layer of the epithelium. f, C-lacZ ×C-GFP mouse. The mOR37C gene is strictly subject to monoallelic expression. Note the location of cell bodies preferentially in the apical cellular layer of the epithelium. Scale bar, 20 μm.
- Fig. 5.
Glomerular pattern in A-lacZ mice.a, Whole-mount view onto the ventral surface of a bulb removed from the cranial cavity. Stained fibers converge on a single target (anterior is to the left, and medial is to thetop). b, Parasagittal section through a bulb stained with X-gal and counterstained with neutral red. A singleblue glomerulus is located on the anteroventral aspect of the bulb. The position of the cribriform plate is indicated by thedashed line (anterior is to the left, and dorsal is to the top). c, Higher magnification identifies the stained area as a single glomerulus.d, Coronal section through the left and right bulbs counterstained with neutral red. Individual glomeruli in the ventral and central region of the bulb are stained blue. They are located in similar positions in both bulbs (dorsal is to thetop). e, Coronal section through the right bulb from a different A-lacZ mouse. The labeled glomerulus is positioned slightly laterally compared withe. f, Coronal sections through the right bulb. Of 40 sections, the first and last are shown. The center of the first glomerulus, as identified by X-gal staining, is located on section 1, the center of the second glomerulus is located on section 40. They are separated by 34 sections without any glomerular X-gal staining. Both labeled glomeruli are located in the ventral region of the bulb but in slightly different mediolateral positions. Scale bars:b, 400 μm; c, 100 μm;d–f, 300 μm.
- Fig. 6.
Glomerular patterns in mOR37-lacZmice. Coronal sections through the right bulbs from variousmOR37-lacZ strains stained with X-gal (dorsal is to the top, and medial is to theleft). a, B-lacZ. The stained glomerulus is located in the ventral and central region of the bulb. b, C-lacZ. The stained glomerulus is also located in the ventral and central region of the bulb.c, A-lacZ × B-lacZ. Two distinct blue-stained glomeruli are visible, which are located adjacent to each other. d, A-lacZ ×B-lacZ. Two glomeruli are stained, separated in the mediolateral dimension by one unlabeled glomerulus. e,A-lacZ × B-lacZ. Of six sections, the first and the last are shown. On the first section, a stained glomerulus is visible in the ventral region of the bulb. On the next three sections, the glomerular X-gal staining disappears but reappears on the consecutive ones. Thus, these two glomeruli are located immediately adjacent to each other in the anteroposterior dimension.f, B-lacZ × C-lacZ. Two glomeruli are stained, separated in the mediolateral dimension by two unlabeled glomeruli. g,A-lacZ × C-lacZ. Two stained glomeruli are visible, located adjacent to each other in the mediolateral dimension. Scale bar: (in a)a–d, f, g, represents 200 μm; e, 200 μm.
- Fig. 7.
Glomerular patterns in mice with differentially tagged mOR37 alleles and genes. a, Whole-mount view of the bulb from an A-GFP mouse. Intensely fluorescent fiber bundles can be seen converging onto a single glomerulus. b, Horizontal section through the nasal cavity and bulb from an A-GFP mouse, counterstained with propidium-iodide. Individual glomeruli in the two bulbs are green fluorescent, located at similar positions (posterior is to the top). c, Cross-section through the right bulb from an A-GFP × A-lacZmouse. Axons from neurons expressing mOR37A but different axonal markers terminate in the same glomerulus, resulting in a yellow appearance. A region from the outer nerve layer (small white box) is shown as an inset; here, fibers that are either green fluorescent (arrow) or red fluorescent (arrowhead) are seen approaching the glomerulus separately. d, Cross-section through the right bulb from a C-GFP ×C-lacZ mouse. Axons from neurons expressingmOR37C but different axonal markers terminate in the same glomerulus. e, Cross-section through the left bulb from an A-GFP × C-lacZmouse. Two distinct glomeruli are stained (A-GFP,green; C-lacZ, red), located adjacent to each other. Medial is to the right.f, Cross-section through the left bulb from anA-GFP × C-lacZ mouse. Again, the two glomeruli are located adjacent to each other, but the doublet is displaced in the mediolateral dimension compared with e. Medial is to the right. g, Cross-section through the left bulb from another A-GFP -C-lacZ mouse. The glomeruli are also located next to each other but are arranged in an inverted orientation compared withe and f. Medial is to theright. h, Cross-section through the right bulb from the mouse shown in e. The two labeled glomeruli are separated by two unlabeled glomeruli. The spatial arrangement is thus discordant between the two bulbs of this mouse. Medial is to the left. i, Four coronal sections (16 μm each) through the bulb from anA-GFP × C-lacZ mouse. The approximate center of the C-lacZ glomerulus is located on section 1. On section 4, the C-lacZ glomerulus is still visible; adjacent to it, the A-GFP glomerulus is now visible. These two glomeruli are located immediately next to each other but in a slightly different anteroposterior dimension. Scale bars: a, 100 μm; b, 200 μm;c–i, 50 μm.
- Fig. 8.
Local permutations in the glomerular array. Schematic three-dimensional representations of a restricted domain of the glomerular array from the anteroventral region of the right olfactory bulb. This region is located behind the cribriform plate and viewed from the nasal cavity; only a small number of glomeruli is drawn. Selected arrangements of mOR37 glomeruli are depicted, with each mOR37 gene corresponding to a single glomerulus for the sake of clarity and simplicity. The Aglomerulus is placed centrally in the three most common situations.A, mOR37A; B,mOR37B; C,mOR37C; a, anterior;p, posterior; m, medial;l, lateral.
Tables
- Table 1.
Percentage of olfactory bulbs with particular numbers of stained glomeruli in mOR37-lacZ strains
A-lacZ n = 30 B-lacZ n = 26 C-lacZ n = 31 A-lacZ ×B-lacZ n = 27 B-lacZ ×C-lacZ n = 29 A-lacZ ×C-lacZ n = 31 1 Glomerulus 77 62 81 0 0 0 2 Glomeruli 23 38 19 48 52 65 3 Glomeruli 0 0 0 45 41 32 4 Glomeruli 0 0 0 7 7 3 A total of 174 bulbs were analyzed by complete serial sectioning.
- Table 2.
Percentage of olfactory bulbs with adjacent and separated stained glomeruli in mOR37-lacZ double-heterozygous mice
A-lacZ × B-lacZ n = 27 B-lacZ × C-lacZ n = 29 A-lacZ × C-lacZ n = 31 Adjacent 78 21 81 Separated 22 79 19 When three or four stained glomeruli are present, the bulb is scored as adjacent if two of these glomeruli are adjacent.
