Seasonal expression of cytoplasmic creatine kinase in the epididymal epithelium of Pelodiscus sinensis

ABSTRACT

During hibernation of Pelodiscus sinensis, sperm mature and are stored in the epididymis. We investigated seasonal changes in the morphology of epithelial cells of the epididymis of P. sinensis and changes in expression of cytoplasmic creatine kinase (CK). We found that the epididymal epithelium proliferates rapidly to form multiple layers from June to September, while the epididymal epithelial cells are arranged in a single layer from October to May. From the March before the mating period to the end of the mating period in September, a large amount of neutral glycoprotein is secreted in the epididymal epithelium and in the sperm aggregation area; after October, the glycoprotein in the epididymis decreases. At sperm maturation, cytoplasmic CK is expressed abundantly in the villous epithelium, which is formed by proliferation of epididymal epithelial cells. During hibernation and reproduction, the epididymal epithelium of P. sinensis exhibits different proliferation and secretion patterns as the animal adapts to two types of sperm storage. Cytoplasmic CK may participate in regulating the energy metabolism of the epididymal epithelium; it is an important enzyme for regulating sperm maturation.

KEYWORDS:

• Creatine kinase
• epididymis
• epithelium
• Pelodiscus sinensis
• seasonal changes
• sperm maturation
• sperm storage
• turtle

Disclosure statement

The authors report no conflict of interest.

Additional information

Funding

This research was supported by National Natural Science Foundation of China [31402278] and the Top Key Discipline of Bioengineering in Zhejiang Province [ZS2018006]. Dr. Shang-Jun Yin was supported by the Zhejiang Province Welfare Technology Applied Research Project [LGN21C190013], the National Key Research and Development Program [2018YFD0900203], the Basic Scientific Research Foundation of Zhejiang Provincial Universities, and the Ningbo Public Service Platform for High-Value Utilization of Marine Biological Resources.