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. Author manuscript; available in PMC: 2011 Mar 25.
Published in final edited form as: Neuron. 2010 Mar 25;65(6):886–898. doi: 10.1016/j.neuron.2010.02.025

Figure 2. Loss of Bhlhb5 gives rise to mice that develop self-inflicted skin lesions due to excessive licking and scratching.

Figure 2

A) Schematic illustrating the Bhlhb5 knockout allele in which the Bhlhb5 gene is replaced by a neomycin expression cassette. Arrow indicates transcriptional start site. Also see Figure S2. B) Photos illustrating the skin lesions on Bhlhb5 knockout mice. C) Behavioral analysis of wild type (+/+), heterozygous (+/−) or Bhlhb5 null (−/−) with pre-existing skin lesions showing proportion of time spent at each activity over a 20-minute period indicates that Bhlhb5 −/− mice spend the majority of their time licking and scratching at the site of lesion, whereas wild type and heterozygous mice divide their time between normal head-to-toe grooming (grooming chain), exploring/ambulating or resting (stationary). Note that, prior to the onset of skin lesions, Bhlhb5 −/− mice do not display abnormal scratching or licking behavior. However, once a very small skin irritation develops, Bhlhb5 −/− mice lick and scratch persistently such that a skin lesion develops very soon thereafter. D) Time course of skin lesion onset reveals that the majority of Bhlhb5 mutants develop skin lesions between 4 and 8 weeks. Also see Figures S3A and S3D.