Ion channels

Atomic proximity between S4 segment and pore domain in Shaker potassium channels. Lainé, M. et al. Neuron 39, 467–481 (2003)

Crystallographic data on the structure of the bacterial channel KvAP indicated that S4 — the voltage-sensing domain — is at the periphery of the channel and moves through the membrane in response to voltage changes. Here, Lainé et al. present a different model for Shaker K+ channels; on the basis of disulphide-bond formation between engineered pairs of cysteines and molecular modelling, they argue that S4 is located between pore domains.

Neurodegenerative disease

Neurodegeneration and defective neurotransmission in a Caenorhabditis elegans model of tauopathy. Kraemer, B. C. et al. Proc. Natl Acad. Sci. USA 18 Jul 2003 (doi:10.1073/pnas.1533448100)

Kraemer et al. created a new transgenic model of tau-induced neurodegeneration by expressing wild-type and mutant forms of human tau in C. elegans. The expression of wild-type tau led to uncoordinated locomotor behaviour, accumulation of tau and neurodegeneration. These phenotypes were exacerbated in worms that expressed the mutant protein.

Neuroimmunology

Polyamines play a critical role in the control of the innate immune response in the mouse central nervous system. Soulet, D. & Rivest, S. J. Cell Biol. 162, 257–268 (2003)

The authors found a link between polyamines and the innate immune response in the nervous system. Challenging mice with systemic lipopolysaccharide increased the neuronal and glial levels of ornithine decarboxylase — the rate-limiting enzyme for the synthesis of polyamines. This treatment also elicited an increase in the production of pro-inflammatory cytokines, which was abolished by inhibiting polyamine synthesis. Similarly, the inhibition of polyamine synthesis prevented neuronal death in a mouse model of innate immune reactivity in the brain.

Neurophysiology

Passive transport disrupts directional path integration by rat head direction cells. Stackman, R. W. et al. J. Neurophysiol. 30 July 2003 (doi:10.1152/jn.00346.2003)

Head-direction cells discharge when the head of a rat points in a preferred direction. Here, the authors manipulated different interoceptive cues to test their importance for maintaining the preferred firing direction under conditions in which external cues were unavailable. Altering proprioceptive cues by passively transporting the rat between locations elicited the most significant shift of the preferred direction, highlighting the relevance of proprioception for spatial navigation under conditions that require path integration.