Ultrastructural changes and asthenozoospermia in murine spermatozoa lacking the ribosomal protein L29/HIP gene

or Hets and WT (Table 1) for testicular weights, a measure of total sperm production. However, in analyses of a minimum of 200 sperm per animal, gross motility (80% reduced) and progressive motility (91% reduced) were significantly (P < 0.001; Table 1) impaired in null sperm, compared to WT. The Het sperm showed 35% and 32% decrease (P < 0.001) in gross and progressive motility (P < 0.001), compared with WT. In addition, when sperm were acrosome-reacted, using the physiologically relevant progesterone-induced enhanced assay, nulls (P < 0.001) and Hets (P < 0.01) showed significantly lower positive numbers than WT (Table 1). Thus the severity of the defects was related to the number of Rpl29 alleles deleted. The striking feature of Rpl29 gene deletion observed in these mice was the morphology of the sperm flagella: ~80% of caudal sperm from each null, and ~40% from Het sperm exhibited flagellar abnormalities characteristic of " dag " defects 5,6 (Figure 1a), significantly (P < 0.001) different from the 3% seen in WT controls (Figure 1a). Despite the very low motility and high incidence of " dag " defects, null sperm were alive, as evident from eosin-nigrosin dye exclusion test (Figure 1b) and normal mitochondrial membrane potential (Figure 1c), both performed as previously described. 4 Testicular morphology seminiferous tubular architecture and germ cell associations were similar in WT and nulls (data not shown). Characterization of the " dag " defects (Figure 1d–1q) revealed a wide range of severity, as reported by others. The angle of flagellar bends ranged from acute to mild (Figure 1d), with the tails either tightly enclosed (Figure 1e and 1f) or loosely bound (Figure 1g) within the plasma membrane. Frequent presence of cytoplasmic droplets in nulls (Figure 1h–1j) suggested incomplete epididymal maturation. The usual 9 + 2 organization of the microtubules and outer dense fibers in normal WT sperm (Figure 1m) was often found disrupted in nulls with either missing (Figure 1n–1p) or disorganized elements (Figure 1q). While the flagellar effects could directly account for the motility loss Dear Editor, We present here the first report linking a specific gene, ribosomal protein L29 (Rpl29), also known as Hip (heparin/heparan sulfate interacting protein), to the mammalian sperm flagellar morphological anomaly termed the " dag " defect. In addition, we show that loss of Rpl29 invariably results in low sperm motility with infertility accompanying this abnormality. Ribosomal protein L29 is one …