Gap junctions between glial cells in mammalian CNS are known to contain several connexins (Cx), including Cx26, Cx30 and Cx43 at astrocyte-to-astrocyte junctions, and Cx29 and Cx32 on the oligodendrocyte side of astrocyte-to-oligodendrocyte junctions. Recent reports indicating that oligodendrocytes also express Cx47 prompted the present studies of Cx47 localization and relationships to other glial connexins in mouse CNS. In view of the increasing number of connexins reported to interact directly with the scaffolding protein zonula occludens-1 (ZO-1), we investigated ZO-1 expression and Cx47/ZO-1 interaction capabilities in brain, spinal cord and Cx47-transfected HeLa cells. From counts of over 9000 oligodendrocytes labeled by immunofluorescence in various brain regions, virtually all of these cells were found to express Cx29, Cx32 and Cx47. Oligodendrocyte somata displayed robust Cx47-immunopositive puncta that were co-localized with punctate labeling for Cx32 and Cx43. By freeze-fracture replica immunogold labeling, Cx47 was abundant on the oligodendrocyte-side of oligodendrocyte/astrocyte gap junctions. By immunofluorescence, labeling for Cx47 along myelinated fibers was sparse in most brain regions, whereas Cx29 and Cx32 were previously found to be concentrated along these fibers. By immunogold labeling, Cx47 was found in numerous small gap junctions linking myelin to astrocytes, but not within deeper layers of myelin. Brain subcellular fractionation revealed a lack of Cx47 enrichment in myelin fractions, which nevertheless contained an enrichment of Cx32 and Cx29. Oligodendrocytes were immunopositive for ZO-1, and displayed almost total Cx47/ZO-1 colocalization. ZO-1 was found to co-immunoprecipitate with Cx47, and pull-down assays indicated binding of Cx47 to the second PDZ domain of ZO-1.Our results indicate widespread expression of Cx47 by oligodendrocytes, but with a distribution pattern in relative levels inverse to the abundance of Cx29 in myelin and paucity of Cx29 in oligodendrocyte somata. Further, our findings suggest a scaffolding and/or regulatory role of ZO-1 at the oligodendrocyte side of astrocyte-to-oligodendrocyte gap junctions. Keywords connexin47; connexin32; connexin43; gap junctions; PDZ domains; glia Gap junctions are localized at specialized cell-to-cell contacts of plasma membranes in which connexin (Cx) proteins form bidirectional intercellular channels that allow passage of ions and *Corresponding author. Tel: +1-204-789-3767; fax: +1-204-789-3934. E-mail address: nagyji@ms.umanitoba.ca (J. I. Nagy).. 1 Present address: Department of Pathology, Weifang Medical College, PR China. NIH Public Access Author ManuscriptNeuroscience. Author manuscript; available in PMC 2007 March 8. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscriptsmall molecules between cells (Goodenough et al., 1996;Kumar and Gilula, 1996;Willecke et al., 2002). In the CNS, astrocytes are extensively coupled by gap junctions (astrocyte-toastrocyte gap junctions [A/A junctions]) that, base...

Utility workers can be exposed to an acute flammability hazard when they are working close to an arcing fault or flashover from electrical equipment or power lines. In the past, it has not been possible to recommend the type of protective clothing that should be worn in these circumstances because no laboratory test method has been available to measure the thermal protective performance (TPP) of fabrics and other laminae against exposure to a high intensity, infrared dominant, radiant energy source similar to that emitted from electrical flashovers. The study describes the use of a recently developed Flash Tester, which, by generating a controlled electrical discharge across welding electrodes, produces radiant flux densities in the 40 to 600 kW/m2 (1 to 15 cals/cm2/s) range. By exposing fabric layers equivalent to various clothing assemblies worn by utility linesmen and a range of 32 flame-retardant (FR) fabrics as single- and multiple-layer specimens, it has been shown that those parts of the body covered by only one fabric layer are exposed to the highest risk of burn injury, whereas for those covered with six or more layers, the risk of burn injury is negligible. The use of single-layer fabrics containing FR fibers or FR finishes provide some additional protection, particularly those with a high mass per unit area (fabric weight), while the use of thicker or lighter colored fabrics does not appear to influence the TPP ratings. More protection is obtained by using two or more fabric layers. However, two layers appear to be effective only when both layers contain fabrics that do not fuse together. Because of strong interactions between fabrics in a multiple-layer assembly, it is not possible to predict the TPP of combined layers worn together from tests of the individual layers.