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Safe anaerobic metabolism Naked mole-rats live in large colonies deep underground in hypoxic conditions. Park et al. found that these animals fuel anaerobic glycolysis with fructose by a rewired pathway that avoids tissue damage (see the Perspective by Storz and McClelland). These results provide insight into the adaptations that this strange social rodent has to make for life underground. They also have implications for medical practice, particularly for understanding how to protect tissues from hypoxia. Science , this issue p. 307 ; see also p. 248

Scorpions are negatively phototactic animals, and physiological data suggests that their photoreceptors are differentially sensitive to light wavelengths ranging from red to ultraviolet. However, behaviour modification resulting from exposure to different wavelengths has not been established. We monitored behavioural responses of animals in small circular arenas while they were presented with different wavelengths of light (red, green, UV, or no light) matched for intensity. In the first experiment using desert grassland scorpions, Paruroctonus utahensis, half of each arena received the light treatment, while the other half was shaded. The results indicated that the amount of time that scorpions spent on the light-exposed side varied depending on the treatment and that avoidance was greatest for UV light followed by green light. In subsequent experiments using both P. utahensis and striped bark scorpions, Centruroides vittatus, the entire arena was subjected to the particular light wavelength while animal locomotory activity was monitored. We found no significant difference in animal responses to randomized, sequential 30 min presentations of all four light treatments. Scorpion activity was greatest during the first 10 min of the 30 min trials; in the first 5 min period, the highest activity levels were in the UV light treatments, followed by the green light treatments. In behavioural tests to either green or IR light, animals moved sporadically and significantly faster under green light compared to IR light treatments. Taken together, we conclude that different wavelengths of light affect scorpion locomotory behaviour differently.

Recent research has proposed a pathway in which sensory neurons expressing the capsaicin activated ion channel TRPV1 are required for histamine-induced itch and subsequent scratching behavior. We examined histamine-induced itch in the African naked mole-rat (Heterocephalus glaber) and found that although naked mole-rats display innate scratching behavior, histamine was unable to evoke increased scratching as is observed in most mouse strains. Using calcium imaging, we examined the histamine sensitivity of naked mole-rat dorsal root ganglia (DRG) neurons and identified a population of small diameter neurons activated by histamine, the majority of which are also capsaicinsensitive. This suggested that naked mole-rat sensory neurons are activated by histamine, but that spinal dorsal horn processing of sensory information is not the same as in other rodents. We have previously shown that naked mole-rats naturally lack substance P (SP) in cutaneous C-fibers, but that the neurokinin-1 receptor is expressed in the superficial spinal cord. This led us to investigate if SP deficiency plays a role in the lack of histamine-induced scratching in this species. After intrathecal administration of SP into the spinal cord we observed robust scratching behavior in response to histamine injection. Our data therefore support a model in which TRPV1-expressing sensory neurons are important for histamine-induced itch. In addition, we demonstrate a requirement for active, SP-induced post-synaptic drive to enable histamine sensitive afferents to drive itch-related behavior in the naked mole-rat. These results illustrate that it is altered dorsal horn connectivity of nociceptors that underlies the lack of itch and pain-related behavior in the naked mole-rat., This work was supported by the Alexander von Humboldt Foundation (EStJS) and NSF grant 0744979 (TJP).