a, The mouse Grb10 locus showing the LacZ:neomycin^r (β-geo) insertion in the Grb10KO allele (not to scale), showing transcriptional start-sites (arrows), numbered exons (boxes), translated regions (filled boxes) and heterologous splice acceptor (SA) and polyadenylation (pA) signals. b, Northern (RNA) blot analysis of Grb10 expression in whole e14.5 embryos. Grb10 transcripts (approx 5.5Kb) were readily detected in wild type (+/+) and Grb10KO^+/p (+/p) but not Grb10KO^m/+ (m/+) samples. c, Northern blot analysis of Grb10 expression in adult brain. Grb10 transcripts were evident in wild type (+/+) and Grb10KO^+/m (m/+) but not Grb10KO^+/p (+/p) samples. d-g, LacZ reporter expression in e11.5 (d-e) and e14.5 (f-g); heterozygous Grb10KO embryos showing opposite imprinting of the two parental alleles in different tissues. h, Neonatal body weight analysis revealed that Grb10KO^m/+, but not Grb10KO^+/p, neonates were overgrown compared to wild type littermates on the day of birth (F_{(2, 90)} = 41.69; p < 0.001). i, Analysis of dissected organs showed that growth enhancement in Grb10KO^m/+ neonates was proportional within most tissues, except the liver, which was disproportionately overgrown (F_{(2, 87)} = 118.60; p < 0.001), and the kidneys and brain, which were spared. j, Stomach weights of wild type and Grb10KO^+/p neonates were not significantly different, suggesting that feeding was not impaired in the mutants (t(36) = 0.38; p = 0.70).

a, A Grb10KO^+/p brain dissected from an e14.5 embryo, showing LacZ reporter expression within the ventral midbrain (Mb), hindbrain (Hb) and ventral spinal cord, but not cortex (Crx) or cerebellum (Cer). b-d, Adult brains, bisected longitudinally, showing LacZ reporter expression, in Grb10KO^+/p (b), but not Grb10KO^m/+ (c) and wild type (d) samples, demonstrating exclusively paternal Grb10 allele expression. e-g, In situ hybridisation autoradiographs of endogenous Grb10 mRNA expression (using probe A, see Fig 1a) within the substantia nigra pars compacta (SNC), supramammillary nucleus (SuM), ventral tegmental area (VTA) (e), dorsal raphe nucleus (DRN) (f) and locus coeruleus (LC) (g) of the adult brain. h-j, Higher resolution microscope images from hybridised slides dipped in photographic emulsion; positive signal (black grains) demonstrates cellular localisation of Grb10 mRNA at the level of figures e-g. k-m, LacZ expression from the paternal Grb10 allele in the brain of Grb10KO^+/p mice faithfully recapitulates endogenous Grb10 expression as reported by in situ hybridisation (in h-j; 4V indicates fourth ventricle). n-p, Histological sections of Grb10KO^+/p adult brain showing colocalisation of immunofluorescence staining for β-galactosidase, expressed from the Grb10 paternal allele, with markers specific for dopaminergic neurones, (dopamine transporter; DAT) within the SNC (n), serotonergic neurons (serotonin; 5-HT) within the DRN (o) and cholinergic inter-neurons (choline acetyltransferase; ChAT) within the caudate putamen (p). Arrows indicate colocalised cells. Arrow heads indicate cells positive for β-gal but negative for the neurochemical marker. Abbreviations: 4V, fourth ventricle; SNR, substantia nigra pars reticulate; Bar, Barrington's nucleus; SuM, supramammillary nucleus; MnR, median raphe nucleus; VTg, ventral tegmental nucleus.

a, Assessment of social dominance using the tube-test revealed that Grb10KO^+/p mutants were significantly more likely to prevail in a forced encounter than were wild type controls (p < 0.05, significance determined by non-parametric Monte Carlo permutation test at the individual level: see supplementary methods for details). b, A typical example of a barbered animal (black mouse), pictured with an unbarbered cage-mate. c, The incidence of facial barbering within cages containing one or more Grb10KO^+/p (+/p) mutant was significantly greater than in control cages containing wild type animals (+/+), other genetically modified strains (other-KO) or Grb10KO^m/+ mutants (m/+) (χ² = 24.86; p < 0.001). d, e, Assessment of social recognition was conducted using a urinary odour habituation-dishabituation test. Grb10KO^+/p mutants were indistinguishable from wild type controls in regard to the number of visits made to the odour source (d; ANOVA, no effect of GENOTYPE F_(1,10) = 0.513, p = 0.49) and duration of these investigations (e; ANOVA, no effect of GENOTYPE F_(1,10) = 0.011, p = 0.92). Mutant and control animals exhibited the significant but comparable increases in both measures on presentation of a second novel odour (visits, p = 0.015; duration, p = 0.032).