Date Published: March 22, 2018
Publisher: Public Library of Science
Author(s): Mariola A. Dietrich, Andrzej Ciereszko, Myung-Geol Pang.
Our recent studies suggested that the freezability of carp semen is related to seminal plasma protein profiles. Here, we aimed to compare the spermatozoa proteomes of good (GF) and poor (PF) freezability semen of carp. To achieve this, we used two-dimensional difference in gel electrophoresis followed by MALDI-TOF/TOF mass spectrometry. The semen was classified as GF or PF based on sperm motility after freeze/thawing. We identified proteins enriched in spermatozoa of GF (22 proteins) and PF (18 proteins) semen. We also identified 12 proteins enriched in the supernatant after cryopreservation of PF semen. Good freezability is related to high concentrations of proteins involved in the maintenance of flagella structure, membrane fluidity, efficient control of Ca2+ and sperm motility, energy production, and antioxidative protection, which likely reflects the full maturation status of spermatozoa of GF semen. On the other hand poor freezability seems to be related to the presence of proteins identified as released in high quantities from cryopreserved sperm of PF. Thus, the identified proteins might be useful bioindicators of freezing resilience and could be used to screen carp males before cryopreservation, thus improve long-term sperm preservation in carp. Data are available via ProteomeXchange with identifier PXD008187.
Cryopreservation has been extensively used in assisted reproductive technology, agriculture, and conservation programs for endangered species. However, in fish breeding, this method is not yet implemented on a commercial level. Cryopreservation is a damaging process that induces oxidative and osmotic stresses, which alter lipid and protein composition, decrease motility and viability, cause damage to mitochondria and sperm tails, and increase sperm DNA fragmentation leading to a decrease in vertebrate sperm quality after cryopreservation [1–7]. For those reasons, cryopreservation protocols have to be carefully optimized in order to minimalize the above-mentioned damages. Several effective protocols for the cryopreservation of carp semen have been established [8–11]. However, these protocols do not produce satisfactory results for some individuals because of differences in samples ability to withstand the freezing-thawing process . Therefore, the identification of markers for predicting carp semen cryopreservation outcomes is a prerequisite for improving sperm cryopreservation protocols.
To our knowledge, this study is the first to present differentially expressed proteins between spermatozoa of good and poor freezability fish semen. Using a 2D-DIGE approach coupled with MALDI-TOF/TOF, comparing spermatozoa of GF and PF semen, we identified differentially expressed proteins. IPA analysis of these sperm proteins revealed distinct canonical pathways for GF and PF semen. We also identified 12 proteins enriched in the supernatant after cryopreservation of poor freezability semen. The obtained results should be valuable for better understanding of the mechanism of sperm freezability in fish especially for carp.