Proteomic characterization and comparison of ram (Ovis aries) and buck (Capra hircus) spermatozoa proteome using a data independent acquisition mass spectometry (DIA-MS) approach

Dataset of Panda sperm proteome

The giant panda (Ailuropoda melanoleuca), a vulnerable species and an icon of wildlife conservation, is still at risk due to habitat fragmentation and a low reproductive rate. To further safeguard the giant panda from extinction, a captive breeding program was established in the mid 1980's, however the growth of this population has been hindered by the poor reproductive ability of captive male giant pandas. To address this, we investigated the sperm proteome of the giant panda as detailed information on sperm proteome is unavailable, as it is a highly specialized area of study. A study of adult panda sperm proteome identified 1921 proteins with enriched domains, including EF-hand, AAA+ ATPase, and WD 40 repeat. A comparison with four other species revealed common sperm proteins related to metabolic processes, especially glycolysis and citrate cycle, which are crucial for sperm energy. Panda-specific proteins were mainly associated with cellular protein metabolism. Serpin domain-related proteins may play a key role in panda semen properties and liquefaction, involving prefoldin beta-like and heat shock chaperonin-binding. This research contributes to understanding giant panda reproduction and aids in conservation efforts.

Punicalagin Protects Ram Sperm from Oxidative Stress by Enhancing Antioxidant Capacity and Mitochondrial Potential during Liquid Storage at 4 °C

The aim of this study was to investigate the effect of punicalagin, an antioxidant, on ram sperm quality. Semen samples were collected and pooled from five rams, then diluted using a Tris-based diluent containing various concentrations (0, 5, 15, 30 and 45 μM) of punicalagin. Sperm motility, plasma membrane integrity, acrosome integrity, total antioxidant capacity (TAC), reactive oxygen species (ROS), malondialdehyde (MDA), mitochondrial membrane potential (MMP), superoxide dismutase (SOD) and catalase (CAT) were measured and analyzed during liquid storage at 4 °C. The results showed that the Tris-based solution containing punicalagin improved sperm motility, plasma membrane integrity, acrosome integrity, TAC, SOD, CAT and MMP, and decreased ROS content and MDA content. At the same time, the semen sample diluted with the Tris-based solution supplemented with 30 μM punicalagin achieved the best effect. The sperm total motility, progressive motility, plasma membrane integrity, acrosome integrity, TAC, SOD, CAT and MMP of the group supplemented with 30 μM punicalagin were significantly (p < 0.05) higher than those of the other groups on the 5th day during the liquid storage at 4 °C. Meanwhile, the ROS content and MDA content were significantly (p < 0.05) lower than those in the other groups. In conclusion, the optimal concentration of punicalagin in the Hu ram semen diluent was determined to be 30 μM. The results indicated that a diluent supplemented with punicalagin could enhance the quality of ram sperm preserved at 4 °C by increasing antioxidant capacity, mitochondrial potential and reducing oxidative stress.

Regulatory T cells play a crucial role in maintaining sperm tolerance and male fertility

Regulatory T cells (Tregs) modulate tissue homeostatic processes and immune responses. Understanding tissue-Treg biology will contribute to developing precision-targeting treatment strategies. Here, we show that Tregs maintain the tolerogenic state of the testis and epididymis, where sperm are produced and mature. We found that Treg depletion induces severe autoimmune orchitis and epididymitis, manifested by an exacerbated immune cell infiltration [CD4 T cells, monocytes, and mononuclear phagocytes (MPs)] and the development of antisperm antibodies (ASA). In Treg-depleted mice, MPs increased projections toward the epididymal lumen as well as invading the lumen. ASA-bound sperm enhance sperm agglutination and might facilitate sperm phagocytosis. Tolerance breakdown impaired epididymal epithelial function and altered extracellular vesicle cargo, both of which play crucial roles in the acquisition of sperm fertilizing ability and subsequent embryo development. The affected mice had reduced sperm number and motility and severe fertility defects. Deciphering these immunoregulatory mechanisms may help to design new strategies to treat male infertility, as well as to identify potential targets for immunocontraception.

TMT-Based Comparative Proteomic Analysis of the Spermatozoa of Buck (Capra hircus) and Ram (Ovis aries)

Spermatozoa are unique cells that carry a library of proteins that regulate the functions of molecules to achieve functional capabilities. Currently, large amounts of protein have been identified in spermatozoa from different species using proteomic approaches. However, the proteome characteristics and regulatory mechanisms of spermatozoa in bucks versus rams have not been fully unraveled. In this study, we performed a tandem mass tag (TMT)-labeled quantitative proteomic analysis to investigate the protein profiles in the spermatozoa of buck (Capra hircus) and ram (Ovis aries), two important economic livestock species with different fertility potentials. Overall, 2644 proteins were identified and quantified via this approach. Thus, 279 differentially abundant proteins (DAPs) were filtered with a p-value < 0.05, and a quantitative ratio of >2.0 or <0.5 (fold change, FC) in bucks versus rams, wherein 153 were upregulated and 126 were downregulated. Bioinformatics analysis revealed that these DAPs were mainly localized in the mitochondria, extracellular and in the nucleus, and were involved in sperm motility, membrane components, oxidoreductase activity, endopeptidase complex and proteasome-mediated ubiquitin-dependent protein catabolism. Specifically, partial DAPs, such as heat shock protein 90 α family class a member 1 (HSP90AA1), adenosine triphosphate citrate lyase (ACLY), proteasome 26S subunit and non-ATPase 4 (PSMD4), act as "cross-talk" nodes in protein-protein networks as key intermediates or enzymes, which are mainly involved in responses to stimuli, catalytic activity and molecular function regulator pathways that are strictly related to spermatozoa function. The results of our study offer valuable insights into the molecular mechanisms of ram spermatozoa function, and also promote an efficient spermatozoa utilization link to fertility or specific biotechnologies for bucks and rams.

Effect of lactoferrin on ram sperm motility after cryopreservation

Objective

The objective of this study was to analyse the differentially abundant proteins caused by freeze-thawing of ram sperm and explore candidate proteins of interest for their ability to improve ram sperm cryopreservation outcomes in vitro .

Methods

Sperm were from three mature Dorper. Fresh and frozen sperm proteins were extracted, and the differentially abundant proteins were analysed by mass spectrometry (MS). Among these proteins, lactoferrin（LTF) was selected to be added before cryopreservation. Next, sperm samples were diluted in Tris extender, with the addition of 0μg/ml,10 μg/ml, 100 μg/ml, 500 μg/ml, 1000 μg/ml of LTF. After thawing, sperm quality evaluated by motility, plasma membrane integrity, mitochondrial activity and reactive oxygen species (ROS).

Results

Cryopreservation significantly altered the abundance of 40 proteins; the abundance of 16 proteins was increased, while that of 24 proteins was decreased. Next, LTF was added to Tris extender applied to ram sperm. The results showed that sperm motility and plasma membrane integrity were significantly improved (p<0.05) by supplementation with 10 μg/ml LTF compared to those in the control group. There was no significant difference in mitochondrial activity between the 0μg/ml group and other groups (p>0.05). Supplementation of the cryoprotective extender with 10 μg/ml LTF led to decreased reactive oxygen species (ROS) levels compared with those in the control and other groups (p<0.05).

Conclusion

LTF is an important protein during cryopreservation, and the addition of 10 μg/ml LTF to a cryoprotective extender can significantly improve the function of frozen ram sperm.

Effect of insulin-like growth factor-1 complex of Simmental bull seminal plasma on post-thawed Kacang buck semen fertility

Background and Aim

Kacang buck sperm is cryosensitive due to the seminal plasma of semen itself. Meanwhile, bull seminal plasma contains the insulin-like growth factor-1 (IGF-1) complex, which is cryoprotective. The addition of the crude protein of Simmental bull seminal plasma increased the quality of post-thawed semen of Kacang buck. The study was conducted to determine the effects of Simmental bull seminal plasma with IGF-1 on the fertility of post-thawed Kacang buck semen.

Materials and Methods

Buck semen was diluted in the following skim milk-egg yolk extender preparations: Without the addition of Simmental bull seminal plasma IGF-1 complex protein (T0); with the addition of 12-μg Simmental bull seminal plasma IGF-1 complex protein (T1); and with the addition of 24-μg Simmental bull seminal plasma IGF-1 complex protein (T2). The extended semen was packed in 0.25-mL straws and frozen. Post-thawed semen fertility was evaluated based on the following variables: Sperm motility, viability, intact plasma membrane (IPM), malondialdehyde (MDA) levels, capacitation status, and acrosome reaction. The difference in each variable among the groups was evaluated using analysis of variance, followed by Tukey's honestly significant difference test, at a 95% level of significance. Meanwhile, principal component analysis (PCA) was used to identify the principal component of semen fertility among the seven parameters.

Results

The T1 group showed the highest sperm motility, viability, IPM, and percentage of incapacitated sperm and the lowest MDA levels, percentage of capacitated sperm, and acrosome reaction. PCA revealed that sperm motility had a moderate to very robust correlation with other variables and is the most crucial parameter, accounting for 80.79% of all variables.

Conclusion

The IGF-1 complex in Simmental bull seminal plasma was useful for increasing the fertility of post-thawed Kacang buck semen, and sperm motility was the principal component of semen fertility.

Transcriptome-wide m6A profiling reveals mRNA post-transcriptional modification of boar sperm during cryopreservation

Background

Cryopreservation induces transcriptomic and epigenetic modifications that strongly impairs sperm quality and function, and thus decrease reproductive performance. N⁶-methyladenosine (m⁶A) RNA methylation varies in response to stress and has been implicated in multiple important biological processes, including post-transcriptional fate of mRNA, metabolism, and apoptosis. This study aimed to explore whether cryopreservation induces m⁶A modification of mRNAs associated with sperm energy metabolism, cryoinjuries, and freezability.

Results

The mRNA and protein expression of m⁶A modification enzymes were significantly dysregulated in sperm after cryopreservation. Furthermore, m⁶A peaks were mainly enriched in coding regions and near stop codons with classical RRACH motifs. The mRNAs containing highly methylated m⁶A peaks (fts vs. fs) were significantly associated with metabolism and gene expression, while the genes with less methylated m⁶A peaks were primarily involved in processes regulating RNA metabolism and transcription. Furthermore, the joint analysis of DMMGs and differentially expressed genes indicated that both of these play a vital role in sperm energy metabolism and apoptosis.

Conclusions

Our study is the first to reveal the dynamic m⁶A modification of mRNAs in boar sperm during cryopreservation. These epigenetic modifications may affect mRNA expression and are closely related to sperm motility, apoptosis, and metabolism, which will provide novel insights into understanding of the cryoinjuries or freezability of boar sperm during cryopreservation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07904-8.

Protein Identification of Spermatozoa and Seminal Plasma in Bottlenose Dolphin (Tursiops truncatus)

Proteins play an important role in many reproductive functions such as sperm maturation, sperm transit in the female genital tract or sperm-oocyte interaction. However, in general, little information concerning reproductive features is available in the case of aquatic animals. The present study aims to characterize the proteome of both spermatozoa and seminal plasma of bottlenose dolphins (Tursiops truncatus) as a model organism for cetaceans. Ejaculate samples were obtained from two trained dolphins housed in an aquarium. Spermatozoa and seminal plasma were analyzed by means of proteomic analyses using an LC-MS/MS, and a list with the gene symbols corresponding to each protein was submitted to the DAVID database. Of the 419 proteins identified in spermatozoa and 303 in seminal plasma, 111 proteins were shared by both. Furthermore, 70 proteins were identified as involved in reproductive processes, 39 in spermatozoa, and 31 in seminal plasma. The five most abundant proteins were also identified in these samples: AKAP3, ODF2, TUBB, GSTM3, ROPN1 for spermatozoa and CST11, LTF, ALB, HSP90B1, PIGR for seminal plasma. In conclusion, this study provides the first characterization of the proteome in cetacean sperm and seminal plasma, opening the way to future research into new biomarkers, the analysis of conservation capacity or possible additional applications in the field of assisted reproductive technologies.

Comparative proteomics analysis reveals the molecular mechanism of enhanced cold tolerance through ROS scavenging in winter rapeseed (Brassica napus L.)

Two winter rapeseed cultivars, "NS" (cold tolerant) and "NF" (cold sensitive), were used to reveal the morphological, physiological, and proteomic characteristics in leaves of plants after treatment at -4°C for 12 h(T1) and 24 h(T2), and at room temperature(T0), to understand the molecular mechanisms of cold tolerance. Antioxidant activity and osmotic adjustment ability were higher, and plasma membrane injury was less obvious, in NS than in NF under cold stress. We detected different abundant proteins (DAPs) related to cold tolerance in winter rapeseed through data-independent acquisition (DIA). Compared with NF, A total of 1,235 and 1,543 DAPs were identified in the NSs under T1 and T2, respectively. Compared with NF, 911 proteins were more abundant in NS only after cold treatment. Some of these proteins were related to ROS scavenging through four metabolic pathways: lysine degradation; phenylalanine, tyrosine, and tryptophan; flavonoid biosynthesis; and ubiquinone and other terpenoid-quinone biosynthesis. Analysis of these proteins in the four candidate pathways revealed that they were rapidly accumulated to quickly enhance ROS scavenging and improve the cold tolerance of NS. These proteins were noticeably more abundant during the early stage of cold stress, which was critical for avoiding ROS damage.