Additional file 4: Figure S4. of Pronounced strain-specific chemosensory receptor gene expression in the mouse vomeronasal organ

High degree of polymorphism and differential expression of VR genes among strains. (A-F) Example track files illustrating the mapping of reads to individual VR genes. Each track is a superposition of four individual samples with SNPs highlighted as vertical lines with substitutions represented as follows: thymine as red, guanine as brown, cytosine as blue, and adenine as green. (PDF 4541 kb

Additional file 5: Figure S5. of Pronounced strain-specific chemosensory receptor gene expression in the mouse vomeronasal organ

Differences in expression level among different clades of VRs. (A) Expression of all V1r clades are represented in all strains. Clade J receptor genes are more highly expressed than receptors of other clades. (B) Expression of all V2r clades are represented in all strains. (PDF 558 kb

Additional file 3: Figure S3. of Pronounced strain-specific chemosensory receptor gene expression in the mouse vomeronasal organ

Strain-specific expression of vomeronasal receptors. Data is displayed as expressed (blue) or not expressed (white) to highlight the exclusive patterns of expression for some of the genes. (PDF 87 kb

Activity-Dependent Modulation of Odorant Receptor Gene Expression in the Mouse Olfactory Epithelium

<div><p>Activity plays critical roles in development and maintenance of the olfactory system, which undergoes considerable neurogenesis throughout life. In the mouse olfactory epithelium, each olfactory sensory neuron (OSN) stably expresses a single odorant receptor (OR) type out of a repertoire of ∼1200 and the OSNs with the same OR identity are distributed within one of the few broadly-defined zones. However, it remains elusive whether and how activity modulates such OR expression patterns. Here we addressed this question by investigating OR gene expression via in situ hybridization when sensory experience or neuronal excitability is manipulated. We first examined the expression patterns of fifteen OR genes in mice which underwent neonatal, unilateral naris closure. After four-week occlusion, the cell density in the closed (sensory-deprived) side was significantly lower (for four ORs), similar (for three ORs), or significantly higher (for eight ORs) as compared to that in the open (over-stimulated) side, suggesting that sensory inputs have differential effects on OSNs expressing different OR genes. We next examined the expression patterns of seven OR genes in transgenic mice in which mature OSNs had reduced neuronal excitability. Neuronal silencing led to a significant reduction in the cell density for most OR genes tested and thinner olfactory epithelium with an increased density of apoptotic cells. These results suggest that sensory experience plays important roles in shaping OR gene expression patterns and the neuronal activity is critical for survival of OSNs.</p></div

Naris closure induces higher expression levels in the closed side for most OR genes expressed in the lateroventral zone 4.

<p>Log2 ratio (x/o), the expression level ratio between the closed (x) and open (o) side, and the p value were obtained from the microarray study <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069862#pone.0069862-Coppola2" target="_blank">[19]</a>. Pattern 1 (similar in both sides) is in regular script and Pattern 3 (closed>open) in <b>bold</b>. The OR genes are sorted based on the log2 ratio and only significant changes (p<0.05) are in <b>bold</b>.</p

Unilateral naris closure differentially alters the cell density of individual OR genes.

<p>(A) The linear length from a coronal section was determined by outlining the basement membrane which separates the olfactory epithelium from the propria lamina. The rectangles indicate the approximate locations from which images in B–D were taken. (B–D) The coronal sections were hybridized with antisense RNA probes of MOR13-4 (dorsal zone, B), MOR174-13 (intermediate zone, C), and MOR244-3 (ventral zone, D). The two images in D were taken under identical conditions from the same section and the staining in the open side appeared much weaker than that in the closed side. Arrows mark examples of labeled cells. Scale bar = 0.5 mm in A and 0.2 mm in B–D.</p

Naris closure causes differential changes in the cell density for different OR genes.

<p>The averaged cell density per linear length is denoted as cell number ± s.e.m./mm (<i>n</i> = number of sections). Pattern 1 (similar in both sides) is in regular script, Pattern 2 (closeditalic, and Pattern 3 (closed>open) in <b>bold</b>. * Cells expressing MOR174-13 were found in both the mediodorsal and intermediate zones. ** Cells expressing MOR0-2 were found in both the intermediate and lateroventral zones.</p

The thickness of mature OSN layer does not differ significantly between the closed and open side.

<p>Coronal sections from 4-week-old mice that underwent neonatal, unilateral naris closure were stained with antibodies against OMP (red) and a neuronal marker Tuj1 (green). (A) A low-magnification image shows an entire section. Scale bar = 0.5 mm. The rectangles indicate the approximate locations where confocal images in B to E were taken. The dashed lines illustrate how the thickness of the mature OSN layer is measured in defined regions of zone 1 and zone 4. (B–E) High-magnification confocal images (projected from a stack of 5 images with z step = 3 µm) were taken from zone 1 and zone 4 in the closed (B, D) and open side (C, E). Scale bars = 20 µm.</p

The cell density for most OR types decreases in OMP-Kir2.1 mice.

<p>The averaged cell density per linear length is denoted as cell number ± s.e.m./mm (<i>n</i> = number of sections). The wild-type data were combined from littermate controls (Kir2.1 negative) and untreated C57Bl/6 mice. The p values were obtained by unpaired, two-tailed <i>t</i> tests.</p

Three-chamber Test for Odor Preference.

<p><b>A</b>) Schematic illustration of a classic 3-chamber design. The positions of odor vials are indicated. Shaded areas in each arm of the chamber indicate the odor zone for behavior analysis (<b>i</b>). Tracking traces of four animals in a control experiment with mineral oil vials in both chambers are shown (<b>ii</b>). <b>B</b>) Scatter plots of time spent in two zones in a control session with mineral oil. Each test session was 10 minutes. Twelve animals were examined. Pair wised <i>t</i>-test <i>p</i> value is indicated. <b>C</b>) Odor preference test for female urine (FU, <b>i</b>) and 2-MBA (<b>ii</b>). The upper panels show the tracking trace of one animal in the behavior chamber. Bar graphs indicate time spent in each zone. The number of animals (n) and <i>p</i> values of pairwise <i>t</i>-test are shown. <b>D</b>) Box plot of the ratio between test odor and MO. Dashed line indicates no difference between two zones. One-way ANOVA <i>p</i> values are indicated.</p