Gap junctions in olfactory neurons modulate olfactory sensitivity

<p>Abstract</p> <p>Background</p> <p>One of the fundamental questions in olfaction is whether olfactory receptor neurons (ORNs) behave as independent entities within the olfactory epithelium. On the basis that mature ORNs express multiple connexins, I postulated that gap junctional communication modulates olfactory responses in the periphery and that disruption of gap junctions in ORNs reduces olfactory sensitivity. The data collected from characterizing connexin 43 (Cx43) dominant negative transgenic mice OlfDNCX, and from calcium imaging of wild type mice (WT) support my hypothesis.</p> <p>Results</p> <p>I generated OlfDNCX mice that express a dominant negative Cx43 protein, Cx43/β-gal, in mature ORNs to inactivate gap junctions and hemichannels composed of Cx43 or other structurally related connexins. Characterization of OlfDNCX revealed that Cx43/β-gal was exclusively expressed in areas where mature ORNs resided. Real time quantitative PCR indicated that cellular machineries of OlfDNCX were normal in comparison to WT. Electroolfactogram recordings showed decreased olfactory responses to octaldehyde, heptaldehyde and acetyl acetate in OlfDNCX compared to WT. Octaldehyde-elicited glomerular activity in the olfactory bulb, measured according to odor-elicited <it>c-fos </it>mRNA upregulation in juxtaglomerular cells, was confined to smaller areas of the glomerular layer in OlfDNCX compared to WT. In WT mice, octaldehyde sensitive neurons exhibited reduced response magnitudes after application of gap junction uncoupling reagents and the effects were specific to subsets of neurons.</p> <p>Conclusions</p> <p>My study has demonstrated that altered assembly of Cx43 or structurally related connexins in ORNs modulates olfactory responses and changes olfactory activation maps in the olfactory bulb. Furthermore, pharmacologically uncoupling of gap junctions reduces olfactory activity in subsets of ORNs. These data suggest that gap junctional communication or hemichannel activity plays a critical role in maintaining olfactory sensitivity and odor perception.</p

Spatial Structure of Emission Intensity in Capacitive RF Discharge of He:Ne Mixture at Moderate Pressures

The spatial structure of emission intensity in a capacitive radio frequency discharge at 13.56 Mhz in He:Ne mixture with total pressures of more than hundreds of Pascal was studied using the optical emission spectroscopy technique. The spectral line distributions at the axis of the discharge gap vs. the distance between two plane aluminium electrodes were found for: the line of 585.2 nm (Ne) and 447.15 nm (He) in 5:1 ratio of the mixture at pressure of 800 Pa for different driving powers 10, 20, and 30 W; the line of 585.2 nm in the range of 733-4393 Pa at power of 20 W in 10:1 ratio of the mixture; lines of 632.8 + 633.4 nm (Ne) at ratios of 5:1, 10:1, 15:1, a power of 20 W, under pressure of 1400 Pa; lines of 585.2 nm, 632.8 + 633.4 nm, 640.2 nm, and 703.2 nm (Ne) and 447.15 nm, 706.52 nm (He), at a pressure of 1467 Pa and a power of 20 W in ratio 10:1. Under chosen operational conditions, the measured relative spectral intensities for all studied lines in the middle of the discharge gap show the existence of the α-regime in the RF discharge. The dc-bias voltage vs. the total pressure and the dc-bias voltage-power characteristics were obtained at certain conditions

Characterization of electron beams emitted from dense plasma focus machines using argon, neon and nitrogen

The measured current traces of two low energy machines namely the AECS PF-2 and INTI PF are used for studying of the produced electron beam features using the modified Lee code (RADPFV5.15REB) at different conditions. The fitting procedures between measured and computed current traces are made for each point of pressure. In the case of AECS PF-2 working with neon, the electron fluence reaches the maximum value 2.35 × 1022 electrons m-2 for 1.6 Torr and the flux achieves 2.42 × 1030 electrons m-2s-1 near 1.5 Torr. The electron number has a peak of 5.74 × 1014 at 0.9 Torr. The computed results demonstarte also the maximum value of the power flow density of 2.44 × 1016 Wm-2, and the superior damage factor of around 1.95 × 1012 Wm-2s0.5 at a pressure of 0.4 Torr. Argon presents the action of radiative cooling topping at highly magnified 6.13 × 1031 m-2s-1 at 0.9 Torr. The damage factor reaches almost 175 × 1012 Wm-2s0.5 for Ar but it is only 1.29 × 1012 Wm-2s0.5 for N2. The huge values for argon are a result of enhanced compression due to radiative cooling. In the case of INTI PF device, the electron energy extends from 58 keV (for N2) to 256 keV (for Ar). The results indicate that the electron fluence ranges from 2 × 1022 electrons m-2 for N2 to 88 × 1022 electrons m-2 for Ar