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Proteinaceous sperm motility inhibitory factor from the female Indian garden lizard, Calotes versicolor
Female sperm storage is an intriguing adaptation exhibited by a wide array of both vertebrates and invertebrates. The mechanisms underlying female sperm storage have remained elusive. Using the Indian garden lizard, C. versicolor as a model organism, we investigated the role of small and high molecular weight factors in this phenomenon. We previously showed three distinct phases of reproductive cycle in this animal with live, motile sperm recovered from the uterovaginal region during the reproductive phase. In the present study, we analyzed the uterovaginal contents using SDS-PAGE, and identified an abundant protein band corresponding to ~55kDa irrespective of the phases of the reproductive cycle. Analysis of the purified protein by LCMS/MS suggested the presence of an unique protein without any homology to the NCBI database (data not shown). Exogenous addition of this protein to washed sperm derived from epididymis, reversibly inhibited the motility of the latter in a concentration and time-dependent fashion suggesting it plays a key role in sperm storage. These studies are likely to offer new avenues to unravel the secrets of female sperm storage seen across the animal taxa and may have novel applications not only in reproductive biology but, even in general cell storage and in preserving endangered animal species.
RD17292 Accepted 28 September 2017
© CSIRO 2017