Review & comment

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  How dangerous is research on H5N1 flu?

  Peter Doherty, Paul Thomas

  Research on how highly pathogenic H5N1 viruses might become transmissible between humans has ignited heated debate on the balance of risks and benefits of such experiments. Peter Doherty and Paul Thomas give their view.

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  Timing development in plants

  G Schaller

  G. Eric Schaller explores the question of how plants integrate hormonal signals into particular developmental pathways, discussing research in BMC Biology on a role for the transcription factor FUSCA3, in concert with ethylene, in timing the conversion of juvenile to adult leaves.

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  Neuroprotective role for microglia

  Mariko Howe, Ben Barres

  Ramified microglia, previously branded as 'resting', protect hippocampal neurons against excitotoxicity according to research published in Journal of Neuroinflammation. Mariko Howe and Ben Barres discuss how these findings add to a growing recognition of active roles for microglia in health and disease.

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  What is a pathogen?

  Liise-anne Pirofski, Arturo Casadevall

  Arturo Casadevall and Liise-anne Pirofski explain in Q&A format the emergent properties of microbial pathogenesis that make the question impossible to answer, and the emergence of new pathogens almost impossible to predict.

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  Signaling by shape shifts

  Ruth Nussinov, Buyong Ma

  Sixteen new conformations of the ligand-binding domain of the cell:cell signaling receptor EphrinA4 are identified in research published in BMC Biophysics. Nussinov and Ma discuss how such conformational diversity allows binding of different ligands to propagate distinct signals through secondary conformational change.