The Joint Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology 2018

To investigate sperm flagellar beating pattern in CRISP deficient mice (#310)

Avinash Gaikwad 1 , Ashwin Nandagiri 2 , David Potter 3 , Prabhakar Ranganathan 2 , Moira O'Bryan 1
  1. School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
  2. Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Victoria, Australia
  3. Monash Micro Imaging - Advanced Optical Microscopy, Monash University, Clayton, Victoria, Australia

In order for successful fertilization, the sperm has to travel a daunting distance to reach the site of fertilization and need to have the mechanical force to penetrate the oocyte. During the journey of sperm, the sperm flagellar waveform transitions from a symmetrical, undulatory flagellar movement to a high-amplitude, asymmetric whip-like motion called hyperactivation. Sperm which cannot achieve hyperactivated motility are unable to fertilize an egg. Hyperactivated motility and flagellar waveform is regulated by Ca2+ influx into the sperm tail via CatSper, a sperm-specific ion channel. The Cysteine-RIch Secretory Proteins (CRISPs) are expressed in the mammalian male reproductive tract and have been shown have ion channel regulatory activity. Data from our lab, and another lab, has suggested that CRISPs may regulate CatSper function, and thus fertility, raising the possibility that CRISPs are regulators of sperm motility. To test this hypothesis, we chose to characterize the sperm flagellar beating pattern in Crisp deficient mice using a novel high-speed high-resolution microscopy technique and a custom-made MATLAB program which utilizes shape mode analysis to study the complex dynamics and pattern of beating sperm flagella. The analysis revealed that sperm from Crisp1-/- and Crisp1/4-/- mice have irregular and disrupted flagellar beating patterns when compared to wild-type sperm. Whereas, Crisp2-/-mice have a distinct motility pattern referred to as ‘stiff mid-piece syndrome’. We find significantly lower beat frequency in sperm from Crisp1-/- and Crisp1/4-/- mice than their respective controls. Moreover, the beat frequency from Crisp1-/- and Crisp1/4-/- mice does not increase upon capacitation. Our data suggests that CRISPs are key regulators of sperm motility and that deficiency could lead to disrupted sperm flagellar beating pattern and infertility.