Hindlimb pain models developed in rats have been transposed to mice, but assumed sciatic nerve neuroanatomic similarities have not been examined. We compared sciatic nerve structural organization in mouse strains (C57BL/6J, DBA/2J, and B6129PF2/J) and rat strains (Wistar, Brown Norway, and Sprague-Dawley). Dissection and retrograde labeling showed mouse sciatic nerve origins predominantly from the third lumbar (L3) and L4 spinal nerves, unlike the L4 and L5 in rats. Proportionate contributions by each level differed significantly between strains in both mice and rats. Whereas all rats had six lumbar vertebrae, variable patterns in mice included mostly five vertebrae in DBA/2J, mostly six vertebrae in C57BL/6J, and a mix in B6129PF2/J. Mice with a short lumbar vertebral column showed a rostral shift in relative contributions to the sciatic nerve by L3 and L4. Ligation of the mouse L4 nerve created hyperalgesia similar to that in rats after L5 ligation, and motor changes were similar after mouse L4 and rat L5 ligation (foot cupping) and after mouse L3 and rat L4 ligation (flexion weakness). Thus, mouse L3 and L4 neural segments are anatomically and functionally homologous with rat L4 and L5 segments. Neuronal changes after distal injury or inflammation should be sought in the mouse L3 and L4 ganglia, and the spinal nerve ligation model in mice should involve ligation of the L4 nerve while L3 remains intact. Strain-dependent variability in segmental contributions to the sciatic nerve may account in part for genetic differences in pain behavior after spinal nerve ligation.

[1] An optical microscope coupled to a flow cell was used to study the ice nucleation properties of uncoated and coated mineral dust and SNOMAX (a proxy for biological ice nucleators made from cells of Pseudomonas syringae) at temperatures ranging from 234 to 247 K. We define the onset conditions as the relative humidity (RH) and temperature at which the first ice nucleation event was observed. The results show that H 2 SO 4 coatings modified the ice nucleation properties of all the minerals studied. For kaolinite and illite, the acid coatings increased the RH over ice (RH i ) required for ice nucleation by ∼30% RH i ; for montmorillonite and quartz, the acid coatings increased the RH i by ∼20% RH i . NH 4 HSO 4 coatings also influenced the ice nucleation properties of kaolinite particles. In addition, our results indicate that SNOMAX is a reasonably good ice nucleus, having onset values between 110 to 120% RH i . In contrast to the mineral studies, sulfuric acid coatings did not hinder the ice nucleating ability of SNOMAX particles. Combined, our results support the idea that anthropogenic emissions of SO 2 and NH 3 may influence the ice-nucleating properties of mineral dust particles. From our laboratory data, we also determined contact angles ( ) between the heterogeneous nuclei and ice embryos according to classical nucleation theory to parameterize the laboratory data for inclusion in atmospheric models. The data show that for uncoated ice nuclei the contact angles are small (below ∼20°), but for mineral particles coated with sulfuric acid, the contact angles are larger (above ∼60°).Citation: Chernoff, D. I., and A. K. Bertram (2010), Effects of sulfate coatings on the ice nucleation properties of a biological ice nucleus and several types of minerals,

Abstract. Recent atmospheric measurements show that biological particles are a potentially important class of ice nuclei. Types of biological particles that may be good ice nuclei include bacteria, pollen and fungal spores. We studied the ice nucleation properties of water droplets containing fungal spores from the genus Cladosporium, one of the most abundant types of spores found in the atmosphere. For water droplets containing a Cladosporium spore surface area of ∼217 µm 2 (equivalent to ∼5 spores with average diameters of 3.2 µm ), 1% of the droplets froze by −28.5 • C and 10% froze by -30

Recent atmospheric measurements show that biological particles are important ice nuclei. Types of biological particles that may be good ice nuclei include bacteria, pollen and fungal spores. We studied the ice nucleation properties of water droplets containing fungal spores from the genus <i>Cladosporium</i>, one of the most abundant types of spores found in the atmosphere. For water droplets containing a <i>Cladosporium</i> spore surface area of ~217 μm² (equivalent to ~5 spores with average diameters of 3.2 μm), 1% of the droplets froze by &minus;28.5 &deg;C and 10% froze by &minus;30.1 &deg;C. However, there was a strong dependence on freezing temperature with the spore surface area of <i>Cladosporium</i> within a given droplet. As such, freezing temperatures for droplets containing 1–5 spores are expected to be approximately &minus;35.1&plusmn;2.3 &deg;C (1&sigma; S.D.). Atmospheric ice nucleation on spores of <i>Cladosporium</i> sp., or other spores with similar surface properties, do not appear to explain recent atmospheric measurements showing that biological particles are important ice nuclei. The poor ice nucleation ability of <i>Cladosporium</i> sp. spores may be attributed to the surface which is coated with hydrophobins (a class of hydrophobic proteins that appear to be widespread in filamentous fungi). Given the ubiquity of hydrophobins on spore surfaces, the current study may be applicable to many fungal species of atmospheric importance