The ability to detect hot temperatures is critical to maintaining body temperature and avoiding injury in diverse animals from insects to mammals. Zebrafish embryos, when given a choice, actively avoid hot temperatures and display an increase in locomotion similar to that seen when they are exposed to noxious compounds such as mustard oil. Phylogenetic analysis suggests that the single zebrafish ortholog of TRPV1/2 may have arisen from an evolutionary precursor of the mammalian TRPV1 and TRPV2. As opposed to TRPV2, mammalian TRPV1 is essential for environmentally relevant heat sensation. In the present study, we provide evidence that the zebrafish TRPV1 ion channel is also required for the sensation of heat. Contrary to development in mammals, zebrafish TRPV1 ϩ neurons arise during the first wave of somatosensory neuron development, suggesting a vital importance of thermal sensation in early larval survival. In vitro analysis showed that zebrafish TRPV1 acts as a molecular sensor of environmental heat (Ն25°C) that is distinctly lower than the sensitivity of the mammalian form (Ն42°C) but consistent with thresholds measured in behavioral assays. Using in vivo calcium imaging with the genetically encoded calcium sensor GCaMP3, we show that TRPV1-expressing trigeminal neurons are activated by heat at behaviorally relevant temperatures. Using knock-down studies, we also show that TRPV1 is required for normal heat-induced locomotion. Our results demonstrate for the first time an ancient role for TRPV1 in the direct sensation of environmental heat and show that heat sensation is adapted to reflect species-dependent requirements in response to environmental stimuli.

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We present the design and experimental validation of a scalable DC microgrid for rural electrification in emerging regions. A salient property of the DC microgrid architecture is the distributed control of the grid voltage, which enables both instantaneous power sharing and a metric for determining the available grid power. A droop-voltage power-sharing scheme is implemented wherein the bus-voltage droops in response to lowsupply/high-demand. Additionally, the architecture of the DC microgrid aims to minimize the losses associated with stored energy by distributing storage to individual households. In this way, the number of conversion steps and line losses are reduced. We calculate that the levelized cost of electricity (LCOE) of the proposed DC microgrid over a 15 year time horizon is $0.35 per kW-hr. We also present experimental results from a scaleddown experimental prototype that demonstrate the steady state behavior, the perturbation response, and the overall efficiency of the system. Moreover, we present fault mitigation strategies for various faults that can be expected to occur in a microgrid distribution system. The experimental results demonstrate the suitability of the presented DC microgrid architecture as a technically advantageous and cost effective method for electrifying emerging regions.

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