Whole extra-charged DNA spermatozoa in the saltwater crocodile (Crocodylus porosus) ejaculate

摘要

Saltwater crocodile spermatozoa examined in this study exhibited unusually high levels of extra DNA charged (2C and 4C) spermatozoa that can be explained by arrested cytokinesis at both meiotic divisions. From the ejaculates of five crocodiles, abnormal spermatozoa containing 2C (1-12%) and 4C DNA (0-2%) charges were discriminated after assessing 1500 spermatozoa using morphological characterisation under fluorescence microscopic and image analysis protocols. Individual crocodiles with a high proportion of 2C spermatozoa in their ejaculate, also showed a high level of DNA fragmentation in 1C sperm cells (8.7-12.7%) but there was no such relationship between DNA fragmentation and 2C sperm. The value of whole extra-charged sperm DNA in the ejaculate as a possible marker for fertility is discussed.