Trehalose improves rabbit sperm quality during cryopreservation

Effect of Five Different Antioxidants on the Effectiveness of Goat Semen Cryopreservation

The effective combination of semen cryopreservation and artificial insemination has a positive effect on the conservation of germplasm resources, production and breeding, etc. However, during the process of semen cryopreservation, the sperm cells are very susceptible to different degrees of physical, chemical, and oxidative stress damage. Oxidative damage is the most important factor that reduces semen quality, which is affected by factors such as dilution equilibrium, change of osmotic pressure, cold shock, and enzyme action during the freezing-thawing process, which results in the aggregation of a large amount of reactive oxygen species (ROS) in sperm cells and affects the quality of semen after thawing. Therefore, the method of adding antioxidants to semen cryoprotective diluent is usually used to improve the effect of semen cryopreservation. The aim of this experiment was to investigate the effects of adding five antioxidants (GLP, Mito Q, NAC, SLS, and SDS) to semen cryoprotection diluent on the cryopreservation effect of semen from Saanen dairy goats. The optimal preservation concentrations were screened by detecting sperm viability, plasma membrane integrity, antioxidant capacity, and acrosomal enzyme activities after thawing, and the experimental results were as follows: the optimal concentrations of GLP, Mito Q, NAC, SLS, and SDS added to semen cryopreservation diluent at different concentrations were 0.8 mg/mL, 150 nmol/L, 0.6 mg/mL, 0.15 mg/ mL, 0.6 mg/mL, and 0.15 mg/mL. The optimal concentrations of the five antioxidants were added to the diluent and analyzed after 1 week of cryopreservation, and it was found that sperm viability, plasma membrane integrity, and mitochondrial activity were significantly enhanced after thawing compared with the control group (P < 0.05), and their antioxidant capacity was significantly enhanced (P < 0.05). Therefore, the addition of the above five antioxidants to goat sperm cryodilution solution had a better enhancement of sperm cryopreservation. This study provides a useful reference for exploring the improvement of goat semen cryoprotection effect.

Effect of Trehalose Supplementation in Egg-Yolk-Free Extender on Conventional Parameters and Gene Expression Related to Reactive Oxygen Species, Apoptosis, and Motility of Frozen Dog Spermatozoa

The present study was conducted to evaluate the effects of trehalose supplementation in egg-yolk (EY)-free tris extender on dog spermatozoa. Pooled spermatozoa were diluted with extender 1 (EY-free tris extender supplemented with 0, 10, 15, 20, or 30 mM trehalose) and cooled (2 × 108 sperm/mL) for 1 hour at 4°C. After that, extender 2 (extender 1 containing 1 M glycerol) was added (v:v) to the diluted sperm, loaded in 0.5-mL straws (1 × 108 sperm/mL), and incubated at 4°C for 30 minutes. The sperm straws were frozen over liquid nitrogen (LN2) vapor for 20 minutes and then plunged directly into LN2. After thawing at 37°C for 25 seconds, sperm progressive motility (CASA), viability (SYBR-14/PI), apoptosis (Annexin V/PI), and reactive oxygen species (ROS; H2DCFDA/PI) were evaluated. Thereafter, the optimal concentrations of trehalose were selected, and the gene expression of BAX, BCL2, NOX5, SMOX, OGG1, and ROMO1 was evaluated after freeze-thawing. Supplementation with 20 and 30 mM trehalose significantly increased sperm progressive motility and viability compared to the control. However, trehalose had no significant effect on sperm ROS or phosphatidylserine translocation index. There were minor numerical increases and decreases in gene expression when the selected optimal concentrations of trehalose (20 and 30 mM) were compared to the control. However, there were no significant differences. We conclude that the addition of trehalose (20 and 30 mM) in EY-free extender could improve sperm motility and viability without significant effects on ROS, apoptosis, or gene expression.

Addition of Vitamin C Mitigates the Loss of Antioxidant Capacity, Vitality and DNA Integrity in Cryopreserved Human Semen Samples

Cryopreservation of human spermatozoa is a necessity for males suffering from infertility who cannot produce fresh semen for insemination. However, current ART cryopreservation protocols are associated with losses of sperm motility, vitality and DNA integrity, which are thought to be linked to the induction of oxidative damage and the toxic properties of commercial cryoprotectants (CPAs). Preventing or mitigating these losses would be hugely beneficial to sperm survival during ART. Therefore, in this in vitro investigation, lipid peroxidation, production of reactive oxygen species, movement characteristics, antioxidant capacity, vitality, and DNA integrity were examined in semen samples both pre- and post-cryopreservation with CPA supplementation. The findings revealed a 50% reduction in antioxidant capacity with CPA addition, which was accompanied by significant increases in generation of reactive oxygen species and formation of lipid aldehydes. These changes were, in turn, correlated with reductions in sperm viability, motility and DNA integrity. Antioxidant supplementation generated bell-shaped dose-response curves with both resveratrol and vitamin C, emphasising the vulnerability of these cells to both oxidative and reductive stress. At the optimal dose, vitamin C was able to significantly enhance vitality and reduce DNA damage recorded in cryopreserved human spermatozoa. An improvement in sperm motility did not reach statistical significance, possibly because additional pathophysiological mechanisms limit the potential effectiveness of antioxidants in rescuing this aspect of sperm function. The vulnerability of human spermatozoa to reductive stress and the complex nature of sperm cryoinjury will present major challenges in creating the next generation of cryoprotective media.

The effects of purslane (Portulaca oleracea) and fennel (Foeniculum vulgare Mill) hydroalcoholic extracts on the functional parameters of human spermatozoa after vitrification

OBJECTIVE

Reactive oxygen species (ROS) are produced during cryopreservation of human sperm and impair sperm function. Antioxidant compounds, such as fennel and purslane, reduce the damaging effects of ROS. This study aimed to evaluate motility parameters, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), intracellular ROS, and DNA damage to determine the optimum concentrations of hydroalcoholic extracts of fennel and purslane for human spermatozoa cryopreservation.

METHODS

Twenty human sperm samples were used and divided into seven equal groups consisting of fennel hydroalcoholic extract (5, 10, and 15 mg/L), purslane hydroalcoholic extract (25, 50, and 100 mg/L), and no additive.

RESULTS

Supplementation of 25 mg/L and 50 mg/L purslane extract and 10 mg/L fennel extract in cryopreservation extender significantly increased the motility and PMI of sperm with a significant reduction in intracellular ROS compared to control groups (p<0.05). A 50 mg/L concentration of purslane extract elevated progressive motility and MMP compared to the control group (p<0.05). No significant differences were seen for motion patterns and DNA damage of frozen-thawed human sperm in extender containing these extracts.

CONCLUSION

The results showed that supplementation of 50 mg/L purslane extract and 10 mg/L fennel extract in semen cryopreservation extender has the potential to decrease intracellular ROS and subsequently elevate the motility and PMI of human sperm.

Effect of sulforaphane on long-term storage of rabbit semen

In this study, it was aimed to determine the effect of sulforaphane (SFN) on rabbit semen cryopreservation. Semen collected from animals was divided into 5 equal volumes as Control, SFN 5 µM, SFN 10 µM, SFN 25 µM and SFN 50 µM groups. Afterwards, semen analyzes were performed. According to our results, there was no statistical difference between the groups at 4°C. However after freezing thawing, the highest total motility, progressive motility and rapid spermatozoa rate was seen in the 10 µM SFN group, while the lowest was observed in the 50 µM SFN group (P<0.05). Static sperm ratio was highest in the 50 µM group, while the lowest was observed in the 10 µM SFN group. When flow cytometry results examined the rate of acrosomal damaged and dead sperm was the lowest in the 10 µM SFN group, a statistical difference was observed between the control group (P<0.05). The highest rate of sperm with high mitochondrial membrane potential was seen in the 5 µM SFN and 10 µM SFN groups. Apoptosis and ROS rates were found to be lower in the experimental groups compared to the control groups (P<0.05). As a result, SFN supplementation at a dose of 10 µM increased the quality of sperm in the freezing and thawing processes of rabbit semen. In conclusion, 10 µM SFN improved the quality of cryopreservation of rabbit semen.

Metabolomics analysis of buck semen cryopreserved with trehalose

Trehalose is commonly used as an impermeable cryoprotectant for cryopreservation of cells, but its cryoprotective mechanism has now not but been determined. This study investigated the cryopreservation impact of trehalose on buck semen cryopreservation and finished metabolic profiling of freeze-thawed media by way of the GC–MS-based metabolomics for the first time. Metabolic pattern recognition and metabolite identification by means of principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and metabolic pathway topology analysis revealed the results of trehalose on buck sperm metabolism at some point of cryopreservation. The results confirmed that trehalose drastically progressed sperm motility parameters and structural integrity after thawing. PCA and PLS-DA analysis discovered that the metabolic patterns of the freezing-thawing media of buck semen cryopreserved with trehalose (T group) or without trehalose (G group, Control) were certainly separated. Using screening conditions of VIP >1.5 and p vaule <0.05, a total of 48 differential metabolites have been recognized, whithin l-isoleucine, L-leucine, L-threonine, and dihydroxyacetone were notably enriched in valine, leucine and isoleucine biosynthesis, glycerolipid metabolism, and aminoacyl-tRNA biosynthesis pathways. In brief, trehalose can efficiently improve membrane structural integrity and motion parameters in buck sperm after thawing, and it exerts a cryoprotective impact with the aid of changing sperm amino acid synthesis and the glycerol metabolism pathway.

Saccharides Influence Sperm Quality and Expressions of Motility and Fertilization-Associated Genes in Cryopreserved Sperm of Pacific Abalone, Haliotis discus hannai

Pacific abalone, Haliotis discus hannai, is a highly commercial seafood in Southeast Asia. The present study aimed to determine the influence of saccharides and vitamins on post-thaw sperm quality, ATP content, fertilization capacity, hatching capacity, and mRNA content of motility and fertilization-associated genes of Pacific abalone. Sperm cryopreserved using saccharides improved the post-thaw sperm quality including motility, acrosome integrity (AI), plasma membrane integrity (PMI), and mitochondrial membrane potential (MMP). However, vitamins (l-ascorbic acid) did not result in any significant improvement in sperm quality. Sperm cryopreserved using saccharides also improved ATP content, DNA integrity, and mRNA content of motility and fertilization-associated genes of post-thaw sperm than sperm cryopreserved without saccharides. Among sperm cryopreserved using different saccharides, post-thaw sperm quality indicators (except PMI) and mRNA content of motility and fertilization-associated genes did not show significant differences between sperm cryopreserved using 3% sucrose (S) combined with 8% dimethyl sulfoxide (DMSO) and sperm cryopreserved using 1% glucose (G) combined with 8% ethylene glycol (EG). However, sperm cryopreserved using 3% S + 8% DMSO showed higher post-thaw sperm quality (motility: 58.4 ± 2.9%, AI: 57.1 ± 3.2%, PMI: 65.3 ± 3.3%, and MMP: 59.1 ± 3.2%), ATP content (48.4 ± 1.8 nmol/ml), and % DNA in tail (2.09 ± 0.20%) than sperm cryopreserved using other saccharides. When sperms were cryopreserved using 3% S + 8% DMSO, the mRNA content of motility (heat shock protein 70, HSP70; heat shock protein 90, HSP90; protein kinase A, PKA-C; axonemal protein 66.0, Axpp66.0; and tektin-4) and fertilization-associated (sperm protein 18 kDa, SP18 kDa) genes were higher than in sperm cryopreserved using other saccharides. However, changes in the mRNA contents of these genes were insignificant between sperm cryopreserved using 3% S + 8% DMSO and 1% G + 8% EG. Taken together, these results indicate that cryopreservation using 3% S + 8% DMSO can improve post-thaw sperm quality and mRNA contents better than other examined cryoprotectants. The present study suggests that 3% S + 8% DMSO is a suitable cryoprotectant for sperm cryopreservation and molecular conservation of this valuable species.

Antioxidant Activity and Oxidative Stress-Oriented Apoptosis Pathway in Saccharides Supplemented Cryopreserved Sperm of Pacific Abalone, Haliotis discus hannai

The Pacific abalone Haliotis discus hannai is a highly commercialized seafood in Southeast Asia. The aim of the present study was to determine the antioxidant activity and oxidative stress-oriented apoptosis pathway in saccharides supplemented cryopreserved sperm of Pacific abalone. Cryopreserved sperm showed impaired antioxidant defenses due to the reduced mRNA abundance of antioxidant genes (CAT, Cu/Zn-SOD, Mn-SOD, GPx, GR, and BCL-2), apoptosis inhibitor (HSP70, and HSP90) gene, and enzymatic antioxidant activity compared to fresh sperm. Such impaired antioxidant defenses caused an increase in the mRNA expression of apoptosis genes (Bax, and Caspase-3), finally leading to apoptosis. The impaired antioxidant defense also increased O₂^•− production and lipid peroxidation (MDA) levels, which further accelerated apoptosis. Considering all the experimental findings, an apoptosis pathway of cryopreserved sperm has been adopted for the first time. Specifically, sperm cryopreserved using 3% sucrose combined with 8% dimethyl sulfoxide (DMSO) showed improved mRNA stability, enzymatic activity, and DNA integrity with reduced O₂^•− production and MDA levels compared to sperm cryopreserved with the other types of examined cryoprotectants (8% ethylene glycol + 1% glucose, 6% propylene glycol + 2% glucose, 2% glycerol + 3% glucose, and 2% methanol + 4% trehalose). The present study suggests that 3% sucrose combined with 8% DMSO is suitable to cryopreserve the sperm of this valuable species for molecular conservation.

Effect of Trehalose and Sucrose in Post-thaw Quality of Crassostrea angulata Sperm

Sperm cryopreservation can be a helpful tool in reproductive management and preservation of biodiversity. However, the freezing methodologies lead to some damage in structure and function of cells that may compromise post-thaw sperm activity. Cryoprotectant supplementation with sugars proved to be a successful strategy to reduce cryodamage in sperm of several species, once allowing to stabilize the plasma membrane constituents. Therefore, this study intends to understand the effects of sugars in the plasma membrane, DNA integrity, and oxidative response during Portuguese oyster sperm cryopreservation. Three cryoprotectants solutions with an initial concentration of 20% dimethyl sulfoxide (DMSO) and 20% DMSO complemented with 0.9 M trehalose or sucrose in artificial seawater were employed. Sperm samples of mature males were individually collected and diluted 1:10 (v/v) in artificial seawater followed by addition of cryoprotectants [1:1 (v/v)]. Thereafter, sperm was loaded into 0.5 ml straws, maintained at 4°C for 10 min, frozen in a programmable biofreezer at -6°C/min from 0 to -70°C, and stored in liquid nitrogen. Samples were thawed in a 37°C bath for 10 s. Several techniques were performed to evaluate post-thaw quality. Sperm motility and DNA integrity were analyzed by using computer-assisted sperm analysis (CASA) software and comet assay. Flow cytometry was employed to determine membrane and acrosome integrity and to detect intracellular reactive oxygen species (ROS) and apoptosis activity. Lipid peroxidation was determined by malondialdehyde (MDA) detection by using spectrophotometry. Sperm antioxidant capacity was evaluated through glutathione peroxidase, glutathione reductase, and superoxide dismutase. Motility was not affected by the extenders containing sugars; these compounds did not reduce the DNA damage. However, both the trehalose and sucrose protected plasma membrane of cells by increasing cell viability and significantly reducing MDA content. The same finding was observed for the ROS, where live cells registered significantly lower levels of ROS in samples cryopreserved with sugars. The activity of antioxidant enzymes was higher in treatments supplemented with sugars, although not significant. In conclusion, the addition of sugars seems to play an important role in protecting the Crassostrea angulata sperm membrane during cryopreservation, showing potential to improve the post-thaw sperm quality and protect the cells from cryoinjuries.

The effect of L-glutamine and trehalose on dog sperm cryopreservation

This study aimed to test different doses of L-glutamine and trehalose in the canine semen diluent while determining their protective effects on spermatological and biochemical indices of the thawed samples. Semen samples were collected from three fertile dogs using the digital manipulation method. The mixed ejaculates were divided into five portions at 37 °C and diluted with additives. Five study groups were formed with L-glutamine (10 and 20 mM), trehalose (25 and 50 mM), and no additives (control). After the dilution, the semen samples were cooled for 1.5 h at 5 °C and frozen (-110 to -120 °C) in liquid nitrogen vapor. Then, they were stored at -196 °C. For spermatological evaluations, samples were thawed at 38 °C for 30 s. L-glutamine (20 mM) was found to be significantly different (P < 0.05) and led to higher percentages of motility, membrane integrity, and acrosome integrity compared to the control group. Considering the total oxidant status (TOS) assay, the lower values were determined in all the antioxidant groups compared to the control group (P < 0.05). Supplementing the semen extender with L-glutamine showed a higher total antioxidant status (TAS) concentration compared to the control group (P < 0.05). As a result of this study, a higher protective effect was found in all the spermatological evaluations after thawing the frozen semen samples, especially in the group containing L-glutamine (20 mM).

Trehalose modifies the protein profile of ram spermatozoa during cryopreservation

As a magical oligosaccharide, trehalose has been revealed to enhance the post-thaw quality of stock semen. However, information regarding the cryoprotective mechanism of trehalose during cryopreservation has not yet been determined. This study was designed to observe the effects of trehalose on the proteome of ram frozen spermatozoa by applying the isobaric tag for relative and absolute quantification (iTRAQ) strategy combined with parallel reaction monitoring (PRM). A total of 1269 proteins were identified. Among them, there were 21 differentially expressed proteins (DEPs), with 9 up-regulated proteins and 11 down-regulated proteins in spermatozoa frozen with trehalose. These DEPs were primarily located in nucleus, cytoplasm, and extracellular region. The Gene Ontology (GO) enrichment analysis demonstrated the involvement of the DEPs in signal transduction, ion binding, oxidoreductase activity, response to stress, and catabolic processes. Based on the STRING analysis, tight functional correlations were observed between 6-phosphogluconate dehydrogenase, fructose-bisphosphate aldolase A isoform 1, 14-3-3 protein epsilon, tyrosine-protein kinase Fer, and beta-hexosaminidase subunit alpha precursor. Furthermore, 10 DEPs were verified using PRM, confirming the accuracy of the iTRAQ data acquired in this study. In conclusion, trehalose can modify the protein profile of ram spermatozoa during cryopreservation, which may be associated with its cryoprotective effects. Additionally, trehalose may function on frozen spermatozoa through antioxidation, involvement in glycolysis, and increment of spermatozoa tolerance to various stresses.

Strategies for Highly Efficient Rabbit Sperm Cryopreservation

The rabbit is a valuable animal for both the economy and biomedical sciences. Sperm cryopreservation is one of the most efficient ways to preserve rabbit strains because it is easy to collect ejaculate repeatedly from a single male and inseminate artificially into multiple females. During the cooling, freezing and thawing process of sperms, the plasma membrane, cytoplasm and genome structures could be damaged by osmotic stress, cold shock, intracellular ice crystal formation, and excessive production of reactive oxygen species. In this review, we will discuss the progress made during the past years regarding efforts to minimize the cell damage in rabbit sperms, including freezing extender, cryoprotectants, supplements, and procedures.

Protective effects of Tribulus terrestris and Cinnamomum zeylanicum extracts and trehalose added to diluents on goat epididymal sperm freezability

This study investigates the effect of adding Tribulus terrestris ethanol extract (TEE) and Cinnamomum zeylanicum ethanol extract (CEE) and trehalose on freezability of goat epididymal spermatozoa. In Experiment 1, the treatments consist of basic extender containing 25, 50 or 100 μg/ml of TEE or CEE. The control contained no additives. Experiment 2 was carried out to compare the effect of best concentrations resulted in the first experiment with 150 mM trehalose added to basic extender. The results of experiment 1 showed that supplementation of 50 μg/ml TEE and 50 μg/ml CEE increased significantly the percentages of motility, progressive motility and viability of cryopreserved spermatozoa, while the level of malondialdehyde concentration was decreased. Moreover, the 50 μg/ml TEE treatment indicate significantly) P < 0.05) the lowest DNA fragmentation among the other treatments. The data obtained from experiment 2 show that all treatments increased significantly) P < 0.05) the percentages of total motility, viability and membrane integrity, and concurrently decreased the rate of MDA compared to control. In addition, the rates of viability and progressive motility were significantly (P < 0.05) higher in diluents contained herb extracts and trehalose. Regarding DNA fragmentation, the results demonstrate that using the extracts and trehalose in diluents decreased the DNA damages and thereby improved the rate of intact sperm heads. In conclusion, the results of this study indicate that 50 μg/ml of Tribulus terrestris and Cinnamomum zeylanicum ethanolic extracts alone and plus trehalose improved the spermatozoa quality and could be used for cryopreservation.

Comparison between Tris-buffer and INRA-82 extenders on the quality of chilled rabbit spermatozoa

<p>The aim of the present study was to compare the effects of tris-buffer and INRA-82 extenders on the quality of cooled rabbit spermatozoa. Pooled semen samples were collected from eight New Zealand White rabbit bucks, divided into three groups and diluted 1:5 with three different semen extenders: INRA-82, tris-citrate glucose (TCG) and tris-citrate trehalose (TCT). Following dilution, the samples were stored at 5°C for up to 48 h. Sperm motility was recorded at 24, 36 and 48 h post-cooling. Furthermore, sperm viability, morphology, membrane integrity, acrosome status and DNA integrity were assessed at 24 h post-cooling. We found that progressive motility percentages were significantly higher (<em>P</em>&lt;0.05) in samples diluted in INRA-82 (61.00, 53.50, 44.00% at 24, 36 and 48 h post-cooling, respectively) than those diluted in either TCG (39.25, 32.00, 19.75%) or in TCT (47.25, 40.50, 29.00%). We also reported that sperm viability, percentage of normal spermatozoa, percentage of spermatozoa with intact acrosome and DNA integrity after 24 h cooling were significantly higher (<em>P</em>&lt;0.05) in INRA-82 diluted samples compared to TCG and TCT diluted ones. In summary, our results show that dilution of rabbit semen in INRA-82 improved sperm physiological parameters post-cooling compared to those diluted in TCG or TCT. Our findings also suggest that INRA-82 is a promising diluent that can be used effectively to maintain the viability of chilled rabbit semen.</p>

C60 Fullerenes Suppress Reactive Oxygen Species Toxicity Damage in Boar Sperm

We report the carboxylated C₆₀ improved the survival and quality of boar sperm during liquid storage at 4 °C and thus propose the use of carboxylated C₆₀ as a novel antioxidant semen extender supplement. Our results demonstrated that the sperm treated with 2 μg mL^-1 carboxylated C₆₀ had higher motility than the control group (58.6% and 35.4%, respectively; P ˂ 0.05). Moreover, after incubation with carboxylated C₆₀ for 10 days, acrosome integrity and mitochondrial activity of sperm increased by 18.1% and 34%, respectively, compared with that in the control group. Similarly, the antioxidation abilities and adenosine triphosphate levels in boar sperm treated with carboxylated C₆₀ significantly increased (P ˂ 0.05) compared with those in the control group. The presence of carboxylated C₆₀ in semen extender increases sperm motility probably by suppressing reactive oxygen species (ROS) toxicity damage. Interestingly, carboxylated C₆₀ could protect boar sperm from oxidative stress and energy deficiency by inhibiting the ROS-induced protein dephosphorylation via the cAMP-PKA signaling pathway. In addition, the safety of carboxylated C₆₀ as an alternative antioxidant was also comprehensively evaluated by assessing the mean litter size and number of live offspring in the carboxylated C₆₀ treatment group. Our findings confirm carboxylated C₆₀ as a novel antioxidant agent and suggest its use as a semen extender supplement for assisted reproductive technology in domestic animals.

Glycogen Synthase Kinase-3 Regulates Sperm Motility and Acrosome Reaction via Affecting Energy Metabolism in Goats

Hyperactivation and acrosome reaction of sperm are pre-requisite steps for fertilization. However, the hyperactivation and acrosome reaction are critically controlled through the phosphorylation of specific proteins. Glycogen synthase kinase-3 (GSK3), a serine/threonine kinase with two different isoforms (α and β), is involved in biochemical signaling pathways. This study was aimed to investigate whether the GSK3α/β is present in goat sperm and its regulatory role in sperm motility and acrosome reaction. GSK3α/β was detected with immunofluorescence and Western blotting. Sperm motility, membrane integrity, acrosome reaction, mitochondrial membrane potential, phospho-Ser21-GSK3α and phospho-Ser9-GSK3β were analyzed. The ATP production and activities of lactate dehydrogenase (LDH), malate dehydrogenase (MDH), and succinate dehydrogenase (SDH) were measured. It was observed that the GSK3α/β was expressed in goat sperm, especially in the peri-acrosomal, mid-piece and principal piece of the tail. The abundance of GSK3α/β in sperm was increased during transit along the epididymis. Addition of either 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) or CHIR99021 significantly increased the sperm motility patterns and GSK3α/β phosphorylation. Interestingly, the adenosine triphosphate (ATP) production, activities of LDH, MDH and SDH were observed to be increased in the CHIR99021 treatment. The results suggested that GSK3α/β regulates sperm motility and acrosome reaction via phospho-ser21-GSK3α and phospho-ser9-GSK3β that involved in the regulation of sperm energy metabolism.

Improved Expression and Optimization of Trehalose Synthase by Regulation of Pglv in Bacillus subtilis

Trehalose synthase (TreS) converts maltose to trehalose, which has several important functions; therefore, enhancing TreS expression is desirable. Here, a recombinant Bacillus subtilis W800N (ΔamyE)-P_glv strain was constructed to achieve enhanced expression of TreS. Process optimization strategies were developed to improve the expression level of TreS in B. subtilis W800N (ΔamyE)-P_glv. Intracellular activity of TreS was induced using 60 g/L of maltose in shake flask culture. The protein activity reached 5211 ± 134 U/g at 33 °C and pH 7.0 in Luria-Bertani medium. A fed-batch fermentation strategy was applied in a 30 L fermenter containing 18 L terrific broth to achieve high cell density by replacing glycerol with high maltose syrup as a carbon source and an inducer. After 32 h of fermentation, recombinant B. subtilis W800N (ΔamyE)-P_glv activity reached 6850 ± 287 U/g dry cell weight. Our results demonstrate the efficiency of the P_glv promoter in increasing the expression of TreS in B. subtilis W800N (ΔamyE)-P_glv.

Melatonin protects rabbit spermatozoa from cryo-damage via decreasing oxidative stress

Mammalian spermatozoa are highly susceptible to reactive oxygen species (ROS) stress. The aim of the present study was to investigate whether and how melatonin protects rabbit spermatozoa against ROS stress during cryopreservation. Semen was diluted with Tris-citrate-glucose extender in presence of different concentrations of melatonin. It was observed that addition of 0.1 mM melatonin significantly improved spermatozoa motility, membrane integrity, acrosome integrity, mitochondrial membrane potential as well as AMP-activated protein kinase (AMPK) phosphorylation. Meanwhile, the lipid peroxidation (LPO), ROS levels and apoptosis of post-thaw spermatozoa were reduced in presence of melatonin. Interestingly, when fresh spermatozoa were incubated with 100 μM H₂O₂, addition of 0.1 mM melatonin significantly decreased the oxidative damage compared to the H₂O₂ treatment, whereas addition of luzindole, an MT1 receptor inhibitor, decrease the effect of melatonin in spermatozoa. It was observed that the glutathione (GSH) content and activities of glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) were significantly increased with addition of melatonin during cryopreservation. In conclusion, addition of melatonin to the freezing extender protects rabbit spermatozoa against ROS attack by enhancing AMPK phosphorylation for increasing the antioxidative defense.

Protective effects of trehalose on frozen-thawed ovarian granulosa cells of cattle

In this study, trehalose was investigated for its cryoprotective effects on ovarian granulosa cells (bGCs) of cattle. Five concentrations of trehalose at 0, 0.2, 0.4, 0.6 and 0.8 mol/L were added to the cryopreservation medium of bGCs, and the effects on the quality of frozen-thawed bGCs were assessed. The results indicate that the use of cryopreservation medium containing 0.2 and 0.4 mol/L of trehalose resulted in a greater rate of bGC viability compared to those of other groups (P<0.05). Culturing with trehalose at 0.2 and 0.4 mol/L increased 17β- estradiol (E₂)and decreased progesterone (P₄)production (P < 0.05) in post-thawed bGCs. Compared with the control group, the intracellular Ca²⁺ concentrations of frozen-thawed bGCs were less in all treatment groups (P<0.05), and the least Ca²⁺ concentration was observed in the group containing 0.4 mol/L trehalose. The plasma membrane potentials of frozen-thawed bGCs were greater in the groups with 0.2 and 0.4 mol/L trehalose, and the group treated with 0.4 mol/L trehalose had the greatest membrane potential in comparison to other groups (P < 0.05). The relative abundance of the CYP19 mRNA in frozen-thawed bGCs was greater in the groups containing 0.2, 0.4 and 0.6 mol/L trehalose, and relative abundances of FSHR and BCL2 mRNA were greater in the group of bGCs treated with 0.2 mol/L trehalose (P<0.05). Trehalose treatment at 0.4, 0.6 and 0.8 mol/L had an inhibitory effect on BAX gene transcription in frozen-thawed bGCs (P<0.05). In summary, trehalose exhibited a greater cryoprotective effect on bGCs than basic cryopreservation medium.

Effects of oligomeric proanthocyanidins on quality of boar semen during liquid preservation at 17 °C

The use of antioxidants is an important aspect in the preservation of boar semen. Oligomeric proanthocyanidins (OPC) are an effective natural antioxidants that scavenges free radicals and reactive oxygen species (ROS). This study was designed to investigate the antioxidative effect of OPC on boar semen quality during liquid preservation at 17 °C. The effects of different concentrations of OPC on sperm quality variables, antioxidant effects and fertility were analyzed in this experiment. Semen collected from six Guanzhong-Black boars and was diluted with Beltsville thawing solution (BTS). During the process of liquid preservation at 17 °C, the variables assessed were measured and analyzed every 24 h. The addition of OPC improved boar sperm motility, acrosome integrity, membrane integrity, and mitochondrial membrane potential as compared with that of the control group (P <  0.05). Meanwhile, malondialdehyde content (MDA) and ROS content was less after adding OPC, thereby improving the total antioxidant capacity (T-AOC) (P <  0.05). Different concentrations of OPC have different degrees of protective effects on boar semen quality. The results indicate that 50 μg/mL of OPC was the optimum concentration, and that the conception rate, litter size, and survival rate increased at this concentration as compared with that of the control group (P <  0.05). In summary, the addition of OPC to BTS diluents can improve the quality of boar semen at 17 °C during liquid preservation. Further research is needed to understand the mechanism by which OPC provides protection to boar semen during preservation in vitro.