Comparative Analysis of piRNA Profiles Helps to Elucidate Cryoinjury Between Giant Panda and Boar Sperm During Cryopreservation

Abstract

Cryopreservation induces sperm cryoinjuries, including physiological and functional changes. However, the molecular mechanisms of sperm cryoinjury and cryoresistance are still unknown. Cryoresistance or the freeze tolerance of sperm varies across species, and boar sperm is more susceptible to cold stress. Contrary to boar sperm, giant panda sperm appears to be strongly freeze-tolerant and is capable of surviving repeated cycles of freeze-thawing. In this study, differentially expressed (DE) PIWI-interacting RNAs (piRNAs) of fresh and frozen-thawed sperm with different freeze tolerance capacity from giant panda and boar were evaluated. The results showed that 1,160 (22 downregulated and 1,138 upregulated) and 384 (110 upregulated and 274 downregulated) DE piRNAs were identified in giant panda and boar sperm, respectively. Gene ontology (GO) enrichment analysis revealed that the target DE messenger RNAs (mRNAs) of DE piRNAs were mainly enriched in biological regulation, cellular, and metabolic processes in giant panda and boar sperm. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that the target DE mRNAs of DE piRNAs were only distributed in DNA replication and the cyclic adenosine monophosphate (cAMP) signaling pathway in giant panda, but the cAMP, cyclic guanosine monophosphate (cGMP), and mitogen-activated protein kinase (MAPK) signaling pathways in boar sperm were considered as part of the olfactory transduction pathway. In conclusion, we speculated that the difference in the piRNA profiles and the DE piRNAs involved in the cAMP signaling pathway in boar and giant panda may have contributed to the different freeze tolerance capacities between giant panda and boar sperm, which helps to elucidate the molecular mechanism behind sperm cryoinjury and cryoresistance.

Boar Sperm Cryopreservation Improvement Using Semen Extender Modification by Dextran and Pentaisomaltose

“…Boar spermatozoa are one of the most sensitive sperm types to cryopreservation. The resistance of spermatozoa to cryopreservation is highly dependent on their biophysical properties such as the shape, size, and plasma membrane composition, which is mainly linked to a lower cholesterol content and high content of polyunsaturated fatty acids [ 37 , 38 , 39 ].…”

“…Artificial insemination with cryopreserved semen has a positive impact on porcine production and product quality. Multiple seminal doses of boar sperm with high genetic merit can be obtained from one ejaculate, and storage and transport in liquid nitrogen allow the insemination of thousands of sows worldwide [ 38 ]. Another essential use is for the creation of genetic resource banks which preserve the genetic material of endangered, valuable individuals or genetically relevant breeds [ 54 ].…”

piR-121380 Is Involved in Cryo-Capacitation and Regulates Post-Thawed Boar Sperm Quality Through Phosphorylation of ERK2 via Targeting PTPN7

“…In addition to the common changes during cryopreservation, the freezing-thawing procedure also affects other important components related to sperm functions, such as DNA integrity, messenger RNAs (mRNAs), and non-coding RNAs (Ran et al, 2019;Peris-Frau et al, 2021;Wang et al, 2021). Although significant progress has been made in the identification of markers of cryopreservation, including certain mRNA, miRNA transcripts, and proteins, little attention has been paid to piRNAs involved in cryoresistance.…”

Cryopreservation Induces Acetylation of Metabolism-Related Proteins in Boar Sperm

“…The plasma membrane of boar sperm contains a higher concentration of phospholipids compared to other mammals, which increases its vulnerability to cold shock and cryo-injuries [ 6 , 9 , 10 ]. Sperm DNA and mitochondria are also susceptible to cryodamage [ 11 ], which can be related to cryopreservation in terms of differentially expressed mRNA, piRNA and miRNA [ 12 , 13 ]. Despite decades of research on cryopreserving semen, no multipurpose semen additive has been discovered to prevent boar sperm from suffering cryodamage and increase the rate of AI, which would, in turn, result in increased conception and fecundity rates.…”