Sensory neuron sodium channel Nav1.8 is essential for pain at low temperatures

Sensory acuity and motor dexterity deteriorate when human limbs cool down, but pain perception persists and cold-induced pain can become excruciating. Evolutionary pressure to enforce protective behaviour requires that damage-sensing neurons (nociceptors) continue to function at low temperatures. Here we show that this goal is achieved by endowing superficial endings of slowly conducting nociceptive fibres with the tetrodotoxin-resistant voltage-gated sodium channel (VGSC) Na(v)1.8 (ref. 2). This channel is essential for sustained excitability of nociceptors when the skin is cooled. We show that cooling excitable membranes progressively enhances the voltage-dependent slow inactivation of tetrodotoxin-sensitive VGSCs. In contrast, the inactivation properties of Na(v)1.8 are entirely cold-resistant. Moreover, low temperatures decrease the activation threshold of the sodium currents and increase the membrane resistance, augmenting the voltage change caused by any membrane current. Thus, in the cold, Na(v)1.8 remains available as the sole electrical impulse generator in nociceptors that transmits nociceptive information to the central nervous system. Consistent with this concept is the observation that Na(v)1.8-null mutant mice show negligible responses to noxious cold and mechanical stimulation at low temperatures. Our data present strong evidence for a specialized role of Na(v)1.8 in nociceptors as the critical molecule for the perception of cold pain and pain in the cold.     

List of Oregon Scolytidae (Coleoptera) and notes on new records

Listed are 121 species of Scolytidae from Oregon. Ten species are reported from Oregon for the first time: Hylastes tenuis Eichhoff, Phloeosinus scopulorum scopulorum Swaine, Phloeosinus hoferi Blackman, Trypodendron betulae Swaine, Xyleborus xylographus (Say), Trypophloeus striatulus (Mannerheim), T. Thatcheri Wood, Procryphalus mucronatus (LeConte), Pityophthorus scalptor Blackman, and Monarthrum dentigerum (LeConte). The second Oregon specimen of an exotic species, Xyleborus californicus Wood, is reported also.     

Growth rates of mule deer fetuses under different winter conditions

Based on forehead-rump length, growth rates of mule deer ( Odocoileus hemionus ) fetuses in Piceance Basin, Colorado, were slower during severe winters than during moderate ones. Growth rates in both situations were slower than reported for both mule deer and white-tailed deer ( Odocoileus virginianus ) fetuses from captive does.     

Fire effects on small mammal communities in Dinosaur National Monument

Resource specialists at Dinosaur National Monument utilize both planned and unplanned wildland ignitions in big sagebrush ( Artemisia tridentata )--dominated plant communities to restore successional processes, maintain vegetation vigor, and promote diversified landscapes. Short- and long-term effects of prescribed burning on small mammal populations are not well understood. The objectives of this study were to (1) compare small mammal species richness, similarity, and diversity between paired burned and unburned treatment plots, and (2) assess long-term trends of small mammal community responses to burning. Five paired burned/unburned sites having similar vegetation, soils, elevation, and annual precipitation were selected. Prescribed or natural fires occurred on all sites between 1981 and 1995, followed by periodic small mammal removal (trapping) sampling (1--12 years post-burn). Small mammal species richness and diversity were generally higher on unburned than burned plots across post-burn sampling years and sites. Increased abundance of the deer mouse ( Peromyscus maniculatus ) following burning resulted in decreased community diversity. Species similarities between burned and unburned plots were low in early post-burn years but increased in later post-burn years. Short-term shifts in diversity and species similarity resulted from increased deer mouse abundance after burning. However, burning had no long-term impact on species richness and similarity, indicating minimal effect to other small mammal species.     

Fred Neufeld and pneumococcal serotypes: foundations for the discovery of the transforming principle

During the first decade of the twentieth century, the German bacteriologist Fred Neufeld, later Director of the Robert Koch-Institute in Berlin, first described the differentiation of pneumococci into serotypes on the basis of type-specific antisera. This finding was essential for subsequent research at the Rockefeller Institute of Medical Research (RIMR) in New York, and elsewhere, aiming for the conquest of human pneumococcal pneumonia, including antiserum therapy, the discovery that the type-specific antigens were carbohydrates, and the development of effective multivalent pneumococcal polysaccharide vaccines. Moreover, on the basis of pneumococcal serotypes Fred Griffith, in 1928 in London, discovered pneumococcal transformation, and Oswald T. Avery and coworkers, in 1944 at RIMR, identified DNA as the transforming substance. This sequence of events, leading to today’s knowledge that genes consist of DNA, was initiated by a farsighted move of Simon Flexner, first Director of the RIMR, who asked Neufeld to send his pneumococcal typing strains, thus setting the stage for pneumococcal research at RIMR. Here, we describe Fred Neufeld’s contributions in this development, which have remained largely unknown.     

Spatial pattern and interference in pi?on-juniper woodlands of northwest Colorado

The local spatial arrangement of the coniferous trees Pinus edulis and Juniperus osteosperma was mapped in two woodland stands and measured in two shrub-dominated stands in the semiarid Piceance Basin of northwest Colorado. In the woodlands, small trees were often clumped, while medium and large trees were either randomly or uniformly dispersed. Significant regressions were obtained between a tree?s basal area or canopy area and the area of its Dirichlet domain (the region closer to it than to any other tree). Both findings from the woodland stands accord with results obtained by other workers in other vegetation. Like earlier workers, we interpret these patterns to indicate density-dependent mortality and density-dependent depression of growth rates among the trees in the woodlands. In contrast, the trees in the shrub-dominated stands are located at random with respect to each other. However, they are strongly associated with shrub cover. Apparently tree seeds arrive in these stands primarily by long-distance dispersal, and the establishment of seedlings is more likely in the shade of shrubs.     

Diet of the Mogollon vole as indicated by stable-isotope analysis (δ 13 C and δ 15 N)

There are no published studies on the diet of Mogollon voles ( Microtus mogollonensis ) although this species occurs throughout the Southwest in montane forestlands. Mogollon voles are believed to be herbivorous, selecting the vegetative portion of grass as their dominant food source. Herbivores frequently select more easily digested C 3 plants over C 4 plants; we thus expected Mogollon voles would feed primarily on C 3 plants. We collected hair samples from Mogollon voles captured in northern Arizona between 1967 and 2003 and plant samples from some capture sites. Then we compared stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope ratios to investigate dietary preferences for C 3 or C 4 plants. Mean isotope ratios for C 3 plants we sampled were –26.84‰ ( s = 0.17) for δ 13 C and –0.02‰ ( s = 0.32) for δ 15 N. For C 4 plants, mean isotope ratios for δ 13 C and δ 15 N were –15.04 ‰ ( s = 0.38) and –0.74‰ ( s = 0.55), respectively. Mogollon voles were largely herbivorous based on δ 15 N (mean and standard error: 3.77 ± 0.17‰) and used C 3 plants more than C 4 based on δ 13 C (–24.21 ± 0.14‰). Activities that lead to changes in plant species composition or reduction in C 3 plants in montane grasslands and forests (e.g., excessive ungulate grazing) may reduce habitat quality for Mogollon voles.     

Life cycle and incidence of Diplostomum spathaceum Rudolphi (1819) (Trematoda: Diplostomatidae) in Utah

Diplostomum spathaceum (Trematoda: Diplostomatidae) causes a disease known as diplostomatosis (eye fluke disease) and has been found to be widespread throughout the fish of Utah. Totals of 756 snails (5 species), 893 fish (21 species) and 6 species of birds were examined for the presence of larval and adult D. spathaceum from 17 collecting sites throughout Utah. Pathologic effects such as blindness, subacute inflammatory reactions, cornea perforation, and ruptured globe due to diplostomatosis upon the fish host are listed. Fish host and parasite infection data of D. spathaceum for the major lakes of Utah are given.