Fig. 1.

Genetic background influences post-natal survival of β8^–/– mice. (A) Kaplan-Meier survival plot using wild-type (n=40) and β8^–/– (n=39) mice. Note that approximately 60% of β8^–/– mice die by post-natal day 30 (P30) whereas the remaining animals survive for up to 5 months. (B) Weight analysis using P30 and P60 control and mutant male mice (n=7-10 males per genotype, although similar results were observed with female mice). Note that β8^–/– mice weigh significantly less than wild-type littermates. *P<0.0001 compared with wild-type group. (C,D) Images of 4-month-old (P120) wild-type (C) and β8^–/– (D) littermates. β8^–/– mice have a hunched posture and limb paresis; these phenotypes develop with 100% penetrance in mutant mice that survive to adulthood. (E) Footprint analysis performed with P90 wild-type (upper panel) and β8^–/– (lower panel) animals with hind paws painted blue and fore paws painted red. Note that the β8^–/– mouse (like all other β8^–/– mutants examined) displays an abnormal gait characterized by pronounced dragging of the limbs. Arrow indicates direction of movement. (F) Brain tissue homogenates were prepared from P60 wild-type and β8^–/– mice. Detergent-soluble protein lysates were immunoblotted with an anti-β8 integrin polyclonal antibody. Note that β8 integrin protein is expressed in the various brain regions of wild-type mice, but is not detected in β8^–/– animals. SVZ, subventricular zone of lateral ventricle; OB, olfactory bulbs; DG, hippocampal dentate gyrus; CB, cerebellum.