Knockout of Kif6 or Kif9 leads to hydrocephalus and male infertility. (A) Schematic for generating Kif6 (top) and Kif9 (bottom) knockout mice using the CRISPR/Cas9 technique. Targeting sites of sgRNAs (scissors) and genotyping PCR primers are indicated for each knockout model. (B) Representative genotyping PCR results. Genomic DNAs were extracted from P21 mouse tails and amplified by PCR using the indicated primer pairs in A. (C) Complete depletion of Kif6 and Kif9 in the indicated tissues. Tissue lysates were prepared from 2-month-old mice of the indicated genotypes, followed by immunoblotting. Gapdh served as a loading control. (D and E) Morphologies of Kif6- and Kif9-deficient mice. Kif6^−/− mice exhibited a dome-shaped skull (arrow) and kyphosis (arrowhead) with skinny bodies (D). In contrast, Kif9^−/− mice showed a normal appearance (E). (F and G) Representative images of coronal brain sections of Kif6^−/− (F) or Kif9^−/− (G) and their corresponding wide-type littermates. M: month. (H) Quantification of mice with enlarged brain ventricles (n = 60 for Kif6^−/−; n = 11 for Kif9^−/− mice). (I) Survival curves of mice with the indicated genotypes during a 12-month observation period. The number (n) of mice used for each genotype was indicated. (J) Sperm morphologies from wide-type and Kif9^−/− littermates were similar. (K)Kif9^−/− sperms exhibited forward motility defects. Sperm-head displacements in 1 s from the indicated numbers (n) of sperms collected from two P80 mice of each genotype (10 videos per mouse) were pooled together (mean ± SD plus sample dots) and subjected to unpaired two-tailed Student’s t test. (L) Sperm morphologies from wide-type and Kif6^−/− littermates were similar. The images are representative of sperms from two pairs of P88 Kif6^−/− and wild-type littermates. Source data are available for this figure: SourceData F5.