Lipid peroxide formation in relation to membrane stability of fresh and frozen thawed stallion spermatozoa

Effect of selenium nanoparticles-supplemented INRA96 extender on Turkmen stallion sperm quality and lipid peroxidation during storage at 5°C

Oxidative damage to sperm during cooled storage is a significant issue, and selenium with antioxidant potential could be a solution. Moreover, nano-sized selenium offers more advantages compared to its ionic forms. This research aimed to assess the impact of selenium nanoparticles (SeNPs) supplemented in the INRA96 extender on the quality of Turkmen stallion sperm and lipid peroxidation during 72 h of cooled storage. A total of 25 ejaculates were treated using different concentrations of SeNPs, including no SeNPs (Control), 0.5 μM SeNPs (SeNPs 0.5), 1.0 μM SeNPs (SeNPs 1.0), and 1.5 μM SeNPs (SeNPs 1.5). The samples were then evaluated for sperm quality characteristics and lipid peroxidation. The results indicated a significant decrease (P < 0.05) in total and progressive motility, viability, and plasma membrane functionality after 48 h of cooled storage, along with an increase (P < 0.05) in spermatozoa abnormality and malondialdehyde (MDA) levels as the cooled storage time increased. However, SeNPs demonstrated an improvement (P < 0.05) in sperm total motility after 24 h of cooled storage, progressive motility throughout the entire 72-hour period, functionality of the plasma membrane after 48 hours of cooled storage, spermatozoa abnormality after 48 h of cooled storage, and semen MDA levels throughout the cooled storage (P < 0.05). In conclusion, the enrichment of the INRA96 extender with nano-sized selenium can enhance the quality of Turkmen stallion sperm during storage at 5 °C by increasing total, progressive, and curvilinear motilities, improving plasma membrane functionality, and reducing sperm abnormalities and lipid peroxidation.

Preparation, characterization, and ex-vivo evaluation of curcumin-loaded niosomal nanoparticles on the equine sperm quality during cooled storage

Oxidative damage to sperm during cooled storage is a significant issue, and curcumin, with its antioxidant properties, could be a solution. However, its low bioavailability presents a challenge that this study aims to address. The primary objective of this study was to investigate the potential of curcumin-loaded niosomal nanoparticles (Cur-LNN) to enhance the antioxidant properties of curcumin and its effect on sperm quality during 72 h cooled storage. The thin-film hydration procedure was applied to prepare Cur-LNN. The fabricated noisomal nanocarriers were characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Fourier-transform infrared (FT-IR) spectroscopy. Moreover, the encapsulation and loading efficiency, in vitro release study, and ex-vivo antioxidant functionality of Cur-LNN on the stallion sperm preserved under cooled storage conditions were assessed. The fabricated Cur-LNN was spherical in shape and had an average particle size of 163.1 ± 1.8 nm, a zeta potential of -34.1 ± 1.9 mV, a poly-dispersity index of 0.339 ± 0.045, an encapsulation efficiency of 92.34 ± 0.18 %, and a loading efficiency of 35.57 ± 1.36 %. Ex-vivo evaluation revealed that supplementation of the semen extender with Cur-LNN has the potential to enhance sperm quality by improving total and progressive motility, plasma membrane functionality, and lipid peroxidation. These results demonstrate that Cur-LNN exhibited stronger antioxidant and protective effects than curcumin. Although further in vivo investigations are warranted, our ex-vivo results suggest that Cur-LNN has the potential to attenuate oxidative damage and can be used to fortify the antioxidant capacity of equine semen under cooled storage conditions.

l-carnitine enhances the kinematics and protects the sperm membranes of chilled and frozen-thawed Peruvian Paso horse spermatozoa

l-carnitine (LC) transports fatty acids to the mitochondria for energy production, reducing lipid availability for peroxidation through β-oxidation. This research examines the effect of LC supplementation to two skimmed milk-based extenders on the cryosurvival of chilled (5ºC) and frozen-thawed Peruvian Paso horse spermatozoa. An initial experiment determined the optimal LC concentration (0, 1, 5, 10, 25, and 50 mM) when added to INRA-96® and UHT (skimmed milk + 6% egg yolk) extenders, using nine ejaculates from three stallions chilled for up to 96 h. Subsequently, the effect of 25 mM LC supplementation (the optimal concentration) on chilling (INRA-96) and freezing (INRA-Freeze®) extenders was evaluated using eight pooled samples from sixteen ejaculates (2 ejaculates/pool) from four stallions. Results indicated that all LC concentrations produced significantly higher values (P<0.05) for kinematic variables (total [TM] and progressive motilities, curvilinear [VCL] and straight-line [VSL] velocity, and beat-cross frequency [BCF]), and the integrity of plasma/acrosome membranes (IPIA) compared to non-supplemented chilled sperm samples for up to 96 h with both extenders. Moreover, the use of 25 mM LC was more efficient (P<0.05) in preserving the post-chilled values of velocity, BCF, and IPIA for the long term than lower LC concentrations (1-10 mM). Post-thaw values of total motility, the amplitude of lateral head displacement (ALH), and IPIA were significantly improved (P<0.05) when INRA-Freeze extender was supplemented with 25 mM LC. In conclusion, supplementation ofl-carnitine to skimmed milk-based extenders enhanced kinematic variables and protected the membrane integrity in chilled and frozen-thawed Peruvian Paso horse spermatozoa.

Correlation between fatty acids levels in chicken, duck, goose, pigeon, quail and turkey egg yolks and post-thawed quality of ram semen

The comparison between adding egg yolks (EY) of chicken, duck, goose, pigeon, Japanese quail or turkey to the Tris glycerol extender on the quality of ram semen before freezing and post-thawing was evaluated. The correlation between fatty acids levels in egg yolks of different avian species and the post-thawed quality of ram semen was studied. The pooled ejaculates collected from five rams were extended with Tris EY glycerol extenders containing the EY of chicken, duck, goose, pigeon, quail or turkey and cryopreserved at -196°C. The straws were evaluated before freezing and post-thawing for sperm motility using a sperm cell analyser, vitality using a FluoVit kit and abnormality using a SpermBlue stain besides plasma-membrane and DNA integrities using a hypo-osmotic swelling test and a Halomax kit, respectively. The moisture, ash, protein and fatty acid (FA) contents of EY of chicken, duck, goose, pigeon, quail and turkey were analysed using a gas chromatograph. The chicken and quail EY extenders significantly improved the total progressive motility (32.05 ± 1.41 and 31.68 ± 1.43, respectively), vitality, plasma membrane and DNA integrities and abnormalities of post-thawing ram semen in comparison with other EY extenders. Pigeon EY had the lowest saturated fatty acids (SFAs) in comparison with the other types of EYs. The chicken and turkey EYs had the lowest percentage of (monounsaturated fatty acids) MUFAs in comparison with the other types of EYs. The highest percentage of polyunsaturated fatty acids (PUFAs) was observed in the turkey, pigeon and chicken EYs which were considered double or triple their percentage in duck and goose EYs, respectively. Significant positive correlations existed between SFAs levels and total motility, vitality, plasma membrane functionality and DNA integrity (0.77, 0.80, 0.67, 0.52, respectively). Significant negative correlations existed between gondoic EY levels and total motility, vitality, plasma membrane functionality and DNA integrity. In conclusion, the EYs of duck, goose, pigeon or turkey cannot substitute the chicken EY in ram semen extenders as they gave lower post-thawing quality. The quail EY can be used as a good replacer for chicken EY in the extender used for cryopreservation of ram semen. The EY composition of FAs can significantly affect the quality of ram semen post-thawing.

Soybean lecithin and cholesterol-loaded cyclodextrin in combination to enhances the cryosurvival of dairy goat semen

The objective of the study was to examine the effect of soy lecithin (SL) and cholesterol loaded cryclodestrin (CLC) on cryo-survival of sperm cryopreserved in the presence or absence of seminal plasma in Saanen dairy goats. Tris-based dilutions containing various concentrations of SL (0, 0.5%, 1.0% or 2.0%) and CLC (0, 2.0 g/L, 4.0 g/L or 6.0 g/L CLC) were used to cryopreserve Saanen dairy goat sperm. The quality of frozen-thawed sperm, including progressive motility, viability, acrosome and plasma membrane integrity, as well as fertility were detected. Results found that the optimal combination of the two cryoprotectants was 1.0% SL+4.0 g/L CLC, which significantly increased progressive motility, viability, acrosome and plasma membrane integrity of frozen thawed sperm. The impact of the two cryoprotectants in combination was not affected by the presence of seminal plasma. The conception rates obtained after artificial insemination using sperm cryopreserved with and without seminal plasma were 88.89% and 91.67% (P > 0.05), respectively. The respective values for average number of litter sizes were 1.55 ± 0.17 and 1.56 ± 0.21 (P > 0.05). Therefore, this study improved the cryopreservation efficiency of goat semen, enhanced the sperm cryosurvival, and layed a foundation for the wide application of frozen goat semen.

Enhanced phytotoxicity of 4-chloro-3-Methyphenol and lindane under sodium and potassium salt stresses

Investigating the uptake of organic pollutants by plants under salt stress is critical for evaluating crop contamination, understanding the mechanism of plant uptake, and implementing phytoremediation. The uptake of a highly phytotoxic contaminant, 4-Chloro-3-Methyphenol (CMP, 45 mg L^-1), from solutions by wheat seedling with or without Na⁺ and K⁺ was studied to illustrate the synergistic effect of salt on phytotoxicity of CMP, using uptake kinetics, transpiration, Ca²⁺ leakage and fatty acid saturation as indicators. The influence of Na⁺ and K⁺ on the uptake of lindane, a relatively low toxic contaminant, from soil was also explored. Under CMP-Na⁺ and CMP-K⁺ exposure, the concentrations of CMP in both root and shoot were lower than those under CMP exposure, as a result of the inhibition of transpiration caused by Na⁺ and K⁺ stresses. Low concentration of CMP did not reveal serious toxicity on cell membrane. No apparent difference of MDA generation in root cells was observed, due to the lethal concentration of CMP. The relatively small variation of Ca²⁺ leakage and fatty acid saturation degree in the root cell under exposure of CMP, CMP-Na⁺ and CMP-K⁺, compared to intracellular CMP content, suggested the enhanced phytotoxicity of CMP induced by salt. Higher MDA concentration in shoot cell under CMP-Na⁺ and CMP-K⁺ exposure compared with that under CMP exposure again showed the synergetic toxicity of CMP. High Na⁺ and K⁺ concentration significantly facilitated the uptake of lindane by wheat seedlings in soils, indicating that it could boost the permeability of cell membrane, thereby increasing the toxicity of linande to wheat seedlings. The short-term effect of low salt concentration on the uptake of lindane was not obvious, but long-term exposure also led to increased uptake. In conclusion, the presence of salt could amplify the phtotoxicity of organic contaminant via several mechanisms.

Seminal quality comparison of first and second cryopreserved ejaculates of Alpine kid goats by flow cytometry

Discarding the first ejaculate is recommended as an alternative for improving seminal quality after long sexual resting, especially when semen should be used for cryopreservation. However, when the males are not in sexual resting the necessity to discarding the first ejaculate is still unknown. Therefore, this study aimed to compare by flow cytometry the quality of the first and second ejaculates. Ten kids and uniform goats between 5 and 6 months of age were used in a completely randomized design. Semen collection was carried out every 4 days, until a total of five ejaculates per animal in each treatment was completed. The fresh and frozen semen collected were processed and analyzed using macroscopic and microscopic parameters, resistance test, hypo-osmotic medium test, and flow cytometry (FC). The FC parameters were production of reactive oxygen species, plasma and acrosomal membrane integrity, and lipid peroxidation of the plasma membrane. The ejaculates did not differ for the resistance test, the reactivity in the hypo-osmotic medium and for the macroscopic and microscopic seminal parameters, except for sperm volume and concentration. The first ejaculate had a higher percentage of minor and total defects. None of the FC parameters analyzed differed between the first and second ejaculates. The first and second ejaculates demonstrated similar seminal qualities, so for Alpine kid goats without a sexual resting period, discarding the first ejaculate it is not recommended.

Impact of quercetin, carnosine, and ozone in the cryopreservation on Nellore (Bos indicus) semen

The objective of this study was to reduce the effects of cryoinjury caused in bovine semen by cryopreservation. Ejaculates were collected from Nellore bulls and subjected to freezing in C (control), ozone (15, 30, and 60 µg mL^-1 of ozone), quercetin (25, 50, and 100 µg mL^-1 of quercetin), and carnosine groups (100, 200, and 300 ng mL^-1 of carnosine). Samples were evaluated post-thaw (M0) and post-rapid thermoresistance test (M30) for sperm kinetics (total motility, progressive motility, curvilinear speed, linearity and amplitude of lateral head displacement) and cell structure viability (plasma membrane integrity, acrosomal integrity, mitochondrial potential, membrane fluidity, and lipid peroxidation). There were no differences (P > 0.05) between the control, quercetin, and carnosine-treated groups for the parameters evaluated at M0 and M30. In turn, supplementation with ozone resulted in lower values for sperm kinetics (P < 0.05) and lower mitochondrial potential at M30 (P < 0.05). Quercetin and carnosine at the concentrations used did not promote significant gains in frozen semen, nor did they demonstrate cytotoxicity. We expected to obtain positive results with the use of ozone. Nonetheless, the addition was harmful to the parameters of sperm kinetics, and its effect was not observed as a possible pro-antioxidant. We believe that the fact that the gas did not harm the sperm structure opens avenues for tests with lower dosages, since, by reducing its concentration, we could minimize the damage to sperm kinetics.

Effects of adding mixed chicken and quail egg yolks to the cryodiluent on the quality of ram semen before and after cryopreservation

The effects of adding mixed chicken and Japanese quail egg yolks (EYs) to the cryodiluent on the quality of ram semen before freezing and post-thawing were evaluated. Additionally, the composition of chicken and quail egg EYs and their mixture were analyzed for results explanation. The semen was collected from rams (n = 5) and extended with cryodiluent containing the EY of chicken, quail or their mixture (1:1). The extended semen was chilled slowly to 5 °C within 2 h and equilibrated for 2 h, before frozen on the liquid nitrogen vapor and cryopreserved at -196 °C. The straws were evaluated before freezing and post-thawing for sperm motility, vitality and abnormality besides plasma-membrane and DNA integrities. The moisture, ash, protein, and fatty acid (FA) contents of chicken EY, quail EY and their mixture were analyzed. Sperm vitality, plasma membrane integrity and DNA integrity before freezing were significantly (P < 0.05) higher in quail EY than chicken EY and mixed EYs cryodiluent. The chicken EY extender significantly improved the vitality, plasma membrane and DNA integrities of post-thawed ram semen in comparison with quail EY or mixed EYs extenders. While, the post-thawing sperm abnormalities was lower (P ≤ 0.05) in quail EY than chicken EY and mixed EYs cryodiluent. The post-thawing sperm motion kinetics parameters were higher in quail EY than chicken EY and mixed EYs cryodiluent. The highest percentages of moisture, ash, saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) were detected in quail EY had. While, the highest percentages of fat, protein and polyunsaturated fatty acids (PUFAs) were detected in chicken EY. In conclusion, using of chicken EY can improve total motility, vitality, plasma membrane integrity and DNA integrity of cryopreserved ram semen. While, using of quail EY can improve sperm abnormalities and kinetic motion parameters of cryopreserved ram semen. Mixing chicken and quail EYs added no value for post-thawing ram semen parameters.

Evaluation of Chilled Dog Semen Extended With Sperm Activator

Within modern biotechnology, different tools and methodologies have been developed to maximize canine semen conservation protocol to optimize reproductive results. In the last decades, the survival of chilled semen has been prolonged from 2 to 3 days with the first basic diluents, to 10–14 days with the modern extenders. However, their main limitation is that sperm quality decreases during cold storage. Sperm activators (SA) have been produced to provide the molecules necessary to maximize the sperm survival and quality with the aim to enhance fertility and prolificacy. In this study, the effect of commercial extender SA (Theriosolution® Canine AI extender -Chile-) was recorded by daily evaluation of chilled semen for 14 days. In this experiment, sperm-rich ejaculate fraction was collected from six adult healthy Neapolitan Mastiff dogs. The semen evaluation started immediately after collection (d0), and after that a next generation extender was added (d0) for every 24 h from d1 (with and without SA) to d14, to determine spermatozoa progressive motility, velocity of forward progression (VFP), morphology, and integrity of the spermatic membrane. The initial sperm concentration of extended semen was 417.3 ± 170.4 x 106/mL (mean ± SEM) with 85.89 ± 4.76% of MNS (morphologically normal sperm), 84.47 ± 5.22 % live sperm, and pH of 6.2 ± 2.8. The initial VFP was 3.83 ± 0.48, but after 1 min with SA, it rises to 4.45 ± 0.45 (P &lt; 0.001). The sperm progressive motility parameter increases significantly (P &lt; 0.05) in experimental trial, respect to control, starting to d2 at finish (except for d7). The VFP analysis significantly increases in experimental trial (P &lt; 0.05) during most days of the study with the exclusion of d3 and d14. To evaluate the seminal characteristics over time, the experiment was divided into T1 (d0–d5), T2 (d6–d10), and T3 (d11–d14) (P &lt; 0.001) in evaluation of morphology and membrane functionality. The MNS reached 70% at d10 and finally 65% at d14, being considered normal and possibly fertile. With Host-s, 65% of MNS were also achieved at d14. The presence of glucose and fructose in the diluents used for refrigeration can exert very important effects given the fact that metabolic routes have been found in both sugars, providing both different and complementing effects. It can be concluded that the use of SA prior to artificial insemination improves the quality of chilled semen significantly, although it does not reverse the effects of deterioration due to cellular metabolism over time.

Utility of carboxylated poly L-lysine for the liquid storage of bottlenose dolphin semen

Assisted reproduction techniques are required to maintain a genetically diverse captive population of bottlenose dolphins. These techniques include semen preservation, and liquid storage has been proposed as a suitable alternative to cryopreservation, but the optimum conditions, in terms of temperature, duration, and media, have yet to be fully established. The aim of this study, therefore, was to determine the optimum temperature for the liquid storage of dolphin semen during a 14-day period and the usefulness of carboxylated poly-L-lysine (CPLL) as an additive to the semen extender used for the liquid storage. The semen was collected from a mature male dolphin housed at the Kagoshima Aquarium, Japan, transferred into a Beltsville (BF5F) extender, and analyzed for motility and characteristics after five-fold dilution. The optimum temperature was determined by evaluating sperm viability after liquid storage at 4, 17, or 36 °C, and the usefulness of CPLL was evaluated at concentrations of 0%, 0.5%, 1.0%, 2.0%, and 3.0% (v/v) at the optimum temperature. Sperm stored at 4 ℃ had a greater motility maintenance compared with samples stored at 17 or 36 ℃. The most efficacious storage regimen at various time points occurred when there was addition of CPLL at 1.0% (v/v) in terms of sperm motility and other relevant determinations, with this storage approach having greater efficacy that samples stored without CPLL. The most efficacious processes for preserving bottlenose dolphin sperm functions is storage at 4 °C and with there being semen extender supplementation of 1% CPLL.

Metabolomic signature of spermatozoa established during holding time is responsible for differences in boar sperm freezability

Holding at room temperature is the first step in most boar semen cryopreservation protocols. It is well accepted that a holding time (HT) of 24 h increases sperm cryotolerance. However, the effect of HT on ejaculates with different freezability is not entirely clear. The aim of this study was to understand how HT influences spermatic and seminal plasma metabolite profiles of boar ejaculates and how these possible changes affect freezability. Twenty-seven ejaculates were collected and extended to 1:1 (v: v) with BTS and split into two aliquots. The first aliquot was cryopreserved without holding time (0 h), and the second was held at 17°C for 24 h before cryopreservation. Spermatozoa and seminal plasma were collected by centrifugation at two times, before HT (0 h) and after HT (24 h), and subsequently frozen until metabolite extraction and UPLC-MS analysis. After thawing, the semen samples were evaluated for kinetics, membrane integrity, mitochondrial potential, membrane lipid peroxidation, and fluidity. The ejaculates were then allocated into two phenotypes (good ejaculate freezers [GEF] and poor ejaculate freezers [PEF]) based on the percent reduction in sperm quality (%RSQ) as determined by the difference in total motility and membrane integrity between raw and post-thaw samples cryopreserved after 24 h of HT. The metabolic profile of the seminal plasma did not seem to influence ejaculate freezability, but that of the spermatozoa were markedly different between GEF and PEF. We identified a number of metabolic markers in the sperm cells (including inosine, hypoxanthine, creatine, ADP, niacinamide, spermine, and 2-methylbutyrylcarnitine) that were directly related to the improvement of ejaculate freezability during HT; these were components of metabolic pathways associated with energy production. Furthermore, PEF showed an up-regulation in the arginine and proline as well as the glutathione metabolism pathways. These findings help to better understand the effect of holding time on boar sperm freezability and propose prospective metabolic markers that may predict freezability; this has implications in both basic and applied sciences.

Effect of glutathione on pre and post-freezing sperm quality of Indian red jungle fowl (Gallus gallus murghi)

During cryopreservation sperm encounter oxidative stress due to higher production of ROS molecules and insufficient natural antioxidant defence system. Therefore, present study was designed to identify the effects of various glutathione (GSH) concentrations on Indian red jungle fowl (Gallus gallus murghi) sperm quality and fertility pre-freezing and post-thaw incubation hours. Semen was collected from eight cocks and qualified semen ejaculates having motility >65% were pooled after initial evaluation. Semen was divided in four aliquots, diluted with red fowl extender (1:5) at 37 °C having GSH 0 mM (control), 0.1 mM, 0.5 mM and 1.0 mM, cryopreserved and stored at (-196 °C) in liquid nitrogen. Semen quality was assessed at post dilution, cooling, equilibration, and freeze-thawing at 0, 2 and 4 h of incubation at 37 °C. Sperm motility, plasma membrane integrity, viability, acrosome integrity and mitochondrial function were recorded highest (P < 0.05) with 0.5 mM GSH in extender at post-dilution, cooling, equilibration, freeze-thawing and 0, 2 and 4 h of incubation. Lipid peroxidation in sperm and seminal plasma were recorded lowest (P < 0.05) with 0.5 mM GSH during cryopreservation stages and post-thawing incubation. Moreover, antioxidant activities (total antioxidant potential and free radical scavenging capacity) were recorded highest (P < 0.05) in extender having 0.5 mM GSH. Fertility rates were recorded higher (P < 0.05) with 0.5 mM GSH compared to control. It is concluded that 0.5 mM GSH in extender improves sperm structural (sperm viability, plasma membrane integrity and acrosome integrity), functional integrity (motility, mitochondrial function) and fertility parameters of Indian red jungle fowl through enriching antioxidant potential and ameliorating the oxidative stress.

Cholesterol Loaded Cyclodextrin Supplementation Enhances the Cholesterol-to-Phospholipid Ratio and Diminishes Oxidative Stress in Jack Spermatozoa During Cryopreservation

The present study was conducted with the hypothesis that addition of cholesterol to the extender would stabilize the sperm membranes by increasing the cholesterol-to-phospholipid (C:P) ratio and would result in an improved post-thaw semen quality and reduce oxidative stress in the jack (Martina franca) semen. Forty-eight ejaculates from six jacks were collected and analyzed for the present study. The freshly collected semen sample of each jack stallion was divided into five equal fractions after addition of the primary extender without cholesterol-loaded cyclodextrin (CLC) (C) and with 1, 1.5, 2, and 3 mg/mL CLC to obtain 120 × 10⁶ sperm/mL spermatozoa concentration. The semen was cryopreserved using customized freezing protocols. Evaluation of seminal parameters, the C:P ratio, and the oxidative status of jack spermatozoa was analyzed at all stages of cryopreservation. The oxidative status in the jack semen was evaluated by measuring malondialdehyde, glutathione and total antioxidant capacity levels. The results indicated that the mean percent values for various seminal quality parameters and the oxidative parameters were found to be significantly higher (P < .05) in CLC-treated groups with the highest values for 2 mg of CLC/120 × 10⁶ spermatozoa. In conclusion, the present study revealed that the supplementation of CLC before cryopreservation has significantly reduced the oxidative stress and also increased the C:P ratio during semen cryopreservation process. Furthermore, a reduction in lipid peroxidation levels, reduced damage to the sperm plasma and acrosome membranes and improvement in the post-thaw sperm integrity as well as stability were recorded.

Gene Polymorphisms in Boar Spermatozoa and Their Associations with Post-Thaw Semen Quality

Genetic markers have been used to assess the freezability of semen. With the advancement in molecular genetic techniques, it is possible to assess the relationships between sperm functions and gene polymorphisms. In this study, variant calling analysis of RNA-Seq datasets was used to identify single nucleotide polymorphisms (SNPs) in boar spermatozoa and to explore the associations between SNPs and post-thaw semen quality. Assessment of post-thaw sperm quality characteristics showed that 21 boars were considered as having good semen freezability (GSF), while 19 boars were classified as having poor semen freezability (PSF). Variant calling demonstrated that most of the polymorphisms (67%) detected in boar spermatozoa were at the 3’-untranslated regions (3’-UTRs). Analysis of SNP abundance in various functional gene categories showed that gene ontology (GO) terms were related to response to stress, motility, metabolism, reproduction, and embryo development. Genomic DNA was isolated from sperm samples of 40 boars. Forty SNPs were selected and genotyped, and several SNPs were significantly associated with motility and membrane integrity of frozen-thawed (FT) spermatozoa. Polymorphism in SCLT1 gene was associated with significantly higher motility and plasma membrane integrity of FT spermatozoa from boars of the GSF group compared with those of the PSF group. Likewise, polymorphisms in MAP3K20, MS4A2, and ROBO1 genes were significantly associated with reduced cryo-induced lipid peroxidation and DNA damage of FT spermatozoa from boars of the GSF group. Candidate genes with significant SNP associations, including APPL1, PLBD1, FBXO16, EML5, RAB3C, OXSR1,PRICKLE1, and MAP3K20 genes, represent potential markers for post-thaw semen quality, and they might be relevant for future improvement in the selection procedure of boars for cryopreservation. The findings of this study provide evidence indicating that polymorphisms in genes expressed in spermatozoa could be considered as factors associated with post-thaw semen quality.

Effect of carboxylated poly l-Lysine as a cryoprotectant on post-thaw quality and in vivo fertility of Nili Ravi buffalo (Bubalus bubalis) bull semen

Buffalo bull sperm are more prone to cryo-injuries. Glycerol being the most common permeable cryoprotectant exerts cytotoxic effects on sperm which cause a reduction in fertility. Thus, the exploration of new cryoprotectant is needed. For this purpose, we investigated the effect of carboxylated poly l-Lysine (CPLL) as cryoprotectant used with different concentrations of glycerol on post-thaw sperm motility, kinematics, plasma membrane integrity, mitochondrial membrane potential (MMP), lipid peroxidation (LPO), catalase concentration and in vivo fertility of Nili Ravi buffalo bull semen. In experiment 1, semen samples (n = 15, bulls = 3) were diluted with Tris-citrate-egg yolk extender containing different concentration of CPLL [0% (C0), 0.25% (C0.25), 0.5% (C0.5), 0.75% (C0.75), 1% (C1)]. Each concentration of CPLL was added in extender containing either 7% (G7) or 5% (G5) glycerol. Diluted semen samples were cooled and cryopreserved using standard procedures. Post-thaw total and progressive motility, plasma membrane integrity, acrosome integrity, and MMP were found higher (P < 0.05) in group (G5C0.75) containing 0.75% CPLL and 5% glycerol as compared to the control group (G7C0) and other groups while LPO was recorded lower (P < 0.05) in the same group (G5C0.75). In experiment 2, in vivo fertility was compared between G5C0.75 (5% Glycerol+ 0.75% CPLL; depicted better post-thaw quality) and control group G7C0. Buffaloes were inseminated after 24 h of onset of estrus. Pregnancy diagnosis was performed per rectum at least 60 days post insemination. The fertility rates [56% (58/102) vs. 36% (37/103)] were higher (P < 0.05) in G5C0.75 as compared to the control group G7C0. Based upon these results, this study concludes that the addition of 0.75% CPLL in combination with 5% glycerol in freezing extender improves the post-thaw structure, function and in vivo fertility of Nili Ravi buffalo bull semen.

Effects of media and promoters on different lipid peroxidation assays in stallion sperm

Effects of different media and promoters on lipid peroxidation (LPO) in viable stallion sperm have not been reported. Aims of this study were to determine effects of three media (INRA-96™, Equipro CoolGuard™, and Biggers, Whitten and Whittingham [BWW]), and promoters (iron sulfate-Fe; ultraviolet light-UV; or control-no exposure to promoters) on viable sperm LPO using four different flow cytometric assays (i.e., BODIPY, Liperfluo, 4-hydroxylnonenal [4HNE], malonaldehyde [MDA]). Significant media x promoter interactions were detected using the Liperfluo, 4HNE, and MDA assays (P <  0.05); therefore, data were sorted by media and by promoters. With inclusion of milk-based media, there were similar concentrations of LPO in control samples with use of all LPO assays. The effect of iron, as a promoter of LPO production, was media dependent, and milk-based media protected sperm from iron-induced LPO production when there were assessments with all assays. In contrast, iron promoted LPO in sperm diluted in BWW when there was use of in all assays, except BODIPY, probably because of the different target molecule with use of this assay. Ultraviolet light was the most potent LPO promoter with all media and assays evaluated. Data indicate milk-based extenders are generally more LPO-protective than BWW early in the LPO production pathway (based on BODIPY and Liperfluo assays), but are less protective during the later stages of LPO production (based on 4HNE and MDA assays). The use of different media and promoters of LPO allowed for determination of early and late stages of LPO in viable stallion sperm.

Combined addition of superoxide dismutase, catalase and glutathione peroxidase improves quality of cooled stored stallion semen

During cold storage stallion spermatozoa experience undergo oxidative stress, which can impair sperm function and fertilizing capacity. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) are the main endogenous enzymatic antioxidants in stallion seminal plasma, and counteract reactive oxygen species. Semen dilution reduces the endogenous antioxidant concentrations. The aim of this study was to investigate whether addition of 15 IU/mL each of SOD, CAT, and GPX to diluted stallion semen would ameliorate a reactive oxygen-mediated decrease in semen quality during 72 h of storage at 5 °C. Ejaculates (n = 7) were divided in two aliquots and diluted in INRA 96 without (control) or with addition of antioxidants. Semen analysis was performed at the time of dilution and every 24 h during chilled storage. Antioxidant supplementation completely inhibited the storage-dependent increase in activated caspase 3 (P < 0.05). Concomitantly, the antioxidant-supplemented samples had a greater percentage of viable, motile and rapidly moving sperm than control samples after 72 h storage (P < 0.05). The DNA damage, as evaluated by TUNEL assay and SCSA, increased with storage time (P < 0.05). Antioxidant supplementation did not prevent, but did significantly reduce the increase in DNA strand breakage. The results indicate part of the intrinsic apoptotic pathway leading to effector caspase activation was inhibited, although an activation of molecules with endonuclease activity still occurred. In conclusion, adding equal concentrations of SOD, CAT and GPX to a semen extender suppressed caspase-3 activation and improved preservation of stallion sperm motility and viability during 72 h of storage at 5 °C.

Ameliorative Effect of Ascorbic Acid and Glutathione in Combating the Cryoinjuries During Cryopreservation of Exotic Jack Semen

The present study was designed to study the adverse effects of cryopreservation and evaluation of the cryoprotective effect of reduced glutathione (GSH) and ascorbic acid (AA) supplementation on exotic jack semen in combination or alone. For this, 24 semen samples from four adult and fertile jacks were collected via artificial vagina using an estrus jenny as dummy. After semen collection, the semen was evaluated for various qualitative and quantitative parameters in fresh, cooled, and frozen-thawed semen. The semen pellet was extended with the freezing extender containing either AA (0.9 g/L), GSH (2.5 mM), or combination of both (AA 0.9 g/L + GSH 2.5 mM), and another aliquot was kept as control without adding the antioxidants. The jack semen underwent cryodamage, which was evident by the observation of significant (P < .05) decline in the seminal quantitative parameters at various stages of cryopreservation process. Prefreeze and postthaw semen evaluation revealed that the values of plasma membrane, acrosome integrity, and chromatin integrity were found to be significantly higher (P < .01) in the group of samples supplemented with the combination (0.9 g/L AA +2.5 mM GSH) than AA- and GSH-alone or control groups. Supplementation of antioxidants to the freezing extender improved jack prefreeze and postthaw semen quality with the superiority of GSH over AA alone. From the present study, it was inferred that, exotic jack spermatozoa are susceptible to injuries because of cryopreservation, but these cryo-induced damage can be ameliorated significantly (P < .05) with the use of antioxidants and contribute to the improvement of semen cryopreservation procedures.

Removal of seminal plasma prior to liquid storage of boar spermatozoa: A practice that can improve their fertilizing ability

Seminal plasma (SP) plays a vital role in the maintenance of sperm function and integrity along with being involved in their communication with the female reproductive tract. Under in vitro conditions, although it is generally accepted that boar semen is better preserved when SP is diluted (extended) or removed (cryopreserved), its role during storage is not completely elucidated. In this context, the current study sought to determine the role of SP during storage of boar spermatozoa at 17 °C for 72 h. Thus, two treatments were prepared with semen from the sperm-rich fraction (SRF) of boar ejaculate previous to storage in liquid state: 1) PSP: semen directly extended in Beltsville Thawing Solution (BTS), and 2) ASP: semen first centrifuged with subsequent removal of supernatant (containing SP) followed by suspension of sperm in BTS. From this, two experiments were conducted separately in this work: 1) in vitro and 2) in vivo assays. The former aimed to evaluate how sperm capacity responds to in vitro capacitation (IVC) and whether their quality is affected by previous exposure to SP. In the latter, the objective was to understand how important these previous conditions can be for reproductive performance after artificial insemination (AI). According to our results, the previous removal of SP does not affect sperm quality and the response of these cells to IVC (P > 0.05) along with resulting in a lower percentage of acrosome damage in them [12.87 ± 0.76 (ASP) vs. 16.38 ± 0.73 (PSP)] (P < 0.05). This improved preservation of acrosome integrity in the absence of SP can explain the higher fertility rate (%) [63.27 ± 23.47 (ASP) vs. 38.57 ± 16.30 (PSP)] and number of implanted embryos at 28 days after AI (13.71 ± 4.88 (ASP) vs. 7.16 ± 4.02 (PSP)] (P < 0.05) presented by gilts inseminated with seminal doses of ASP. In conclusion, removal of SP prior to liquid storage of boar sperm for 72 h can be beneficial for their fertilizing ability.

Effects of adding egg yolks of different avian species to Tris glycerol extender on the post-thawing quality of buck semen

The effects of adding egg yolks (EY) of different avian species to the Tris glycerol extender was evaluated for post-thawing quality of buck semen. The semen samples collected from seven Aardi bucks were pooled and diluted 1:4 with the Tris glycerol diluents containing the egg yolks of chicken (C), pigeon (P), goose (G), Japanese quail (Q), duck (D), or turkey (T). The diluted semen samples were gradually cooled to 5 °C within 2 h, equilibrated at 5 °C for 2 h, and then frozen in liquid nitrogen vapor for 8 min before storing them at -196 °C. The frozen straws were thawed at 37 °C for 30 s and evaluated for sperm motility, vitality, abnormality, plasma-membrane integrity, and DNA fragmentation. The malondialdehyde (MDA) and reduced glutathione (GSH) activities were measured. The egg yolk samples of the above-mentioned avian species (n = 7/species) were analyzed for moisture, ash, protein, fatty acid (FA), and trace element contents. The use of the chicken EY (C) diluent resulted in better post-thawing buck semen quality, including the total progressive sperm motility parameters, sperm vitality, plasma membrane intactness, DNA integrity, and sperm abnormalities percentages, in comparison with the EY diluents of the other avian species. The lowest MDA and the highest GSH activities were observed in the C diluent. The chicken EY had the highest percentages of margaric and linolenic FAs and the lowest percentages of palmitoleic and myristic FAs. Moreover, the percentage of oleic FA was lower in the chicken EY than in the EYs of other species, except turkey. Additionally, the chicken EY had the significantly lowest concentration of Cu, Zn, Fe, and Mn. In conclusion, the use of chicken egg yolk extender is recommended for buck semen cryopreservation. The egg yolks of the other avian species studied cannot substitute the chicken EY as they gave poorer post-thawing semen quality. The EY composition, especially FA profile and trace elements concentration, significantly affected the post-thawing quality of buck semen.

Nitric oxide in frozen-thawed equine sperm: Effects on motility, membrane integrity and sperm capacitation

Nitric oxide (NO) is a reactive nitrogen species (RSN) that, over the years, has been shown to be integrated with biological and physiological events, including reproductive processes. NO can affect the functionality of spermatozoa through free radical scavenging, deactivating and inhibiting the production of superoxide anions (O₂^.-). However, the role of NO in mammalian spermatozoa physiology seems paradoxical. The aim of this study was to investigate the effects of NO on motility, hyperactivation, membrane integrity, peroxidation, and capacitation in cryopreserved equine sperm. Ejaculates were collected and cryopreserved. After thawing, samples were centrifuged, suspended in an in vitro fertilization (IVF) medium and incubated with the following treatments: 1) C = control (IVF); 2) A = l-arginine (10 mM - In); 3) L = L-NAME (1 mM - Ih); 4) M = methylene blue (100 mM - Re); 5) AL = L-arginine + L-NAME (In + Ih); 6) AM = L-arginine + methylene blue (In + Re). The samples were evaluated for spermatic kinetics by CASA and other analyses [plasma and acrosomal membranes used the propidium iodide (PI) and Pisum sativum agglutinin (PSA), detection of tyrosine residues phosphorylation in the membrane (F0426), nitric oxide (DAF-2/DA), lipid peroxidation (C11-BODIPY^581/591)] by flow cytometry. The l-arginine treatments reduced MOT, PROG, RAP and LIN only at time 0 min compared to the control and L-NAME. These treatments (MT and MP, VAP, VSL, LIN, RAP) also reduced the sperm movement characteristics but only at the beginning of the incubation period. After this period of incubation, motility recovered. NO removal by methylene blue almost completely inhibited sperm motility, but these treatments had the highest percentages of intact membranes. l-arginine treatments improved acrosome reactions and differed from M and AM. NO production, tyrosine phosphorylation and lipid peroxidation did not differ among treatments, except for M and AM, where a reduction in these variables was detected. Therefore, equine sperm capacitation and the acrosome reaction are part of an oxidative process that involves the participation of ROS, and NO plays an important role in the maintenance and regulation of motility, hyperactivation, induction of acrosome reaction and possibly in capacitation, which are indispensable processes for the fertility of equine sperm.

Cryopreservation and egg yolk medium alter the proteome of ram spermatozoa

Cryopreservation causes significant lethal and sub-lethal damage to spermatozoa. In order to improve freezing outcomes, a comprehensive understanding of sub-lethal damage is required. Cryopreservation induced changes to sperm proteins have been investigated in several species, but few have employed currently available state of the art, data independent acquisition mass spectrometry (MS) methods. We used the SWATH LC-MS method to quantitatively profile proteomic changes to ram spermatozoa following exposure to egg yolk and cryopreservation. Egg yolk contributed 15 proteins to spermatozoa, including vitellogenins, apolipoproteins and complement component C3. Cryopreservation significantly altered the abundance of 51 proteins. Overall, 27 proteins increased (e.g. SERPINB1, FER) and 24 proteins decreased (e.g. CCT subunits, CSNK1G2, TOM1L1) in frozen thawed ram spermatozoa, compared to fresh spermatozoa. Chaperones constituted 20% of the proteins lost from spermatozoa following cryopreservation. These alterations may interfere with both normal cellular functioning and the ability of frozen thawed spermatozoa to appropriately respond to stress. This is the first study to apply SWATH mass spectrometry techniques to characterise proteins contributed by egg yolk based freezing media and to profile cryopreservation induced proteomic changes to ram spermatozoa.

SIGNIFICANCE

This study profiles changes to the sperm proteome induced by exposure to egg yolk based media and the process of cryopreservation, and the biological consequences are discussed.

Freeze-drying of mammalian cells using trehalose: preservation of DNA integrity

The aim of this study was to investigate preservation of biomolecular structures, particularly DNA, in freeze-dried fibroblasts, after loading with trehalose via freezing-induced uptake. Cells were freeze-dried with trehalose alone or in a mixture of albumin and trehalose. Albumin was added to increase the glass transition temperature and storage stability. No viable cells were recovered after freeze-drying and rehydration. FTIR studies showed that membrane phase behavior of freeze-dried cells resembles that of fresh cells. However, one day after rehydration membrane phase separation was observed, irrespective of the presence or absence of trehalose during freeze-drying. Freeze-drying did not affect the overall protein secondary structure. Analysis of DNA damage via single cell gel electrophoresis (‘comet assay’) showed that DNA damage progressively increased with storage duration and temperature. DNA damage was prevented during storage at 4 °C. It is shown that trehalose reduces DNA damage during storage, whereas addition of albumin did not seem to have an additional protective effect on storage stability (i.e. DNA integrity) despite the fact that albumin increased the glass transition temperature. Taken together, DNA in freeze-dried somatic cells can be preserved using trehalose as protectant and storage at or below 4 °C.

Seminal plasma arising from the whole boar sperm-rich fraction increases the stability of sperm membrane after thawing

Boar spermatozoa arising from the sperm-rich ejaculate fraction are reported to have a more stable plasma membrane and are more resistant to cold shock and premature acrosome reaction than spermatozoa from the whole ejaculate. Furthermore, seminal plasma (SP) can increase the cryotolerance of boar spermatozoa, and in other domestic species, it has the ability to reverse cryopreservation damage. This study aimed to evaluate the effects of boar SP arising from the whole sperm-rich ejaculate fraction (SP-SRF) on the integrity, stability, and peroxidation of sperm membranes after thawing. Each ejaculate ( = 24) was divided among 4 treatments: control (CT), centrifuged and suspended in autologous SP-SRF (CS), centrifuged with withdrawn SP-SRF (CW), and post-thawed SP arising from the whole sperm-rich fraction addition to CW (CWSP). After thawing, all treatments were incubated for 5, 60, and 120 min and were analyzed for membrane integrity, fluidity, and peroxidation by flow cytometer. The absence of SP-SRF increased the lipid disorder ( < 0.05) but had no effect on lipid peroxidation ( > 0.05) or membrane integrity ( > 0.05). However, the increase in lipid disorder by withdrawal of SP-SRF was reversed by SP-SRF addition ( < 0.05) to the post-thawing medium, whereas plasma and acrosomal membrane integrity ( > 0.05) and lipid peroxidation ( > 0.05) were unchanged. In conclusion, despite the centrifugation effects, the addition of SP arising from the whole sperm-rich fraction to post-thawed boar semen decreased sperm lipid disorder without an influence of the sperm membrane integrity and peroxidation.

Quality of seminal fluids varies with type of stimulus at ejaculation

The theory of ejaculate economics was mainly built around different sperm competition scenarios but also predicts that investments into ejaculates depend on female fecundity. Previous tests of this prediction focused on invertebrates and lower vertebrate, and on species with high female reproductive potential. It remains unclear whether the prediction also holds for polygynous mammals with low female reproductive potential (due to low litter size and long inter-birth intervals). We used horses (Equus caballus) to experimentally test whether semen characteristics are adjusted to the oestrous cycle of the mare a stallion is exposed to during few moments before ejaculation. We analysed 122 weekly semen samples collected from 16 stallions during exposure to either an oestrous or a dioestrous mare. Semen volume and the rate of motile sperm were higher when stallions were exposed to an oestrous than to a diestrous mare, while total sperm counts and sperm velocity remained unchanged. Sperm collected after exposure to an oestrous mare also showed reduced oxidative degeneration of cell membranes over a period of 48 hours. We conclude that stallions invest more into their seminal fluids when the chance of fertilization is elevated, and that this adjustment of ejaculate quality can happen very quickly.

Suppression of chloromethylphenol accumulation in wheat seedlings by uptake-induced phytotoxicity

Uptake and its induced phytotoxicity are hypothesized to suppress overall organic chemical accumulation in plant. The extent and mechanism of suppression remain rather unknown. This study was conducted to evaluate, at both physiological and cellular levels, the phytotoxicity following plant exposure to an organic chemical and, in turn, the suppression of the organic chemical accumulation in the plant. Root uptake of 4-chloro-3-methylphenol (CMP) in wheat seedlings and subsequent CMP translocation to shoots were determined. Seedling transpiration and fatty acid (FA) profiles of cell membranes, along with malondialdehyde (MDA) generation and K⁺ release in seedling tissues, were quantified. At CMP concentrations of 15, 45, and 60 mg L^-1, CMP accumulations reached maxima of about 8.1, 24.7, 40.6 mg kg^-1 in shoots, and 127.4, 187.2, and 244.3 mg kg^-1 in roots, respectively. Most of these accumulations were lower than those estimated from partition-based models. Seedling transpiration was reduced by about 25% (15 mg L^-1) and 60% (45 mg L^-1 and 60 mg L^-1). As a product of lipid peroxidation, MDA level in roots changed with exposure time following an "elevation-demotion" trend. This suggested that root cells suffered initial severe lipid peroxidation and gradually lost cell functions. This resulted in an increase in FA saturation degree of root cell membranes and hence damage to root cells. This was verified by enhanced K⁺ release from root tissue. The "uptake-induced phytotoxicity-suppressed accumulation" cycle existed in plant uptake involving both physiological and cellular actions to maintain CMP accumulation in wheat seedlings lower than model estimation.

Characterization of functional variables in epididymal alpaca (Vicugna pacos) sperm using imaging flow cytometry

Epididymal alpaca sperm represent an alternative model for the study of alpaca semen. The objective of this study was to characterize the normal values of some functional variables in epididymal alpaca sperm using imaging flow cytometry. Alpaca testicles (n=150) were processed and sperm were recovered from the cauda epididymides. Only 76 samples with acceptable motility and sperm count were considered for assessment by imaging flow cytometry. Acrosome integrity and integrity/viability were assessed by FITC-PSA/PI and FITC-PNA/PI. Mitochondrial membrane potential (MMP) was assessed by MitoTracker CMXRos and MitoTracker Deep Red FM. Lipid peroxidation was evaluated using BODIPY 581/591 C11. Results show that the mean values for acrosome-intact sperm were 95.03±6.39% and 93.34±7.96%, using FITC-PSA and FITC-PNA, respectively. The mean values for acrosome-intact viable sperm were 60.58±12.12% with FITC-PSA/PI and 58.81±12.94% with FITC-PNA/PI. Greater MMP was detected in 65.03±15.92% and 59.52±19.19%, using MitoTracker CMXRos and MitoTracker Deep Red FM, respectively. Lipid peroxidation was 0.84±0.95%. Evaluation of acrosome-intact and acrosome-intact viable sperm with FITC-PSA/PI compared with. FITC-PNA/PI or MMP with MitoTracker CMXRos compared with MitoTracker Deep Red FM were correlated (P<0.05). The MMP using MitoTracker CMXRos was the only variable correlated (P<0.05) with sperm motility (r=0.3979). This report provides a basis for future research related to alpaca semen using the epididymal sperm model.

Cryoprotectant Toxicity: Facts, Issues, and Questions

High levels of penetrating cryoprotectants (CPAs) can eliminate ice formation during cryopreservation of cells, tissues, and organs to cryogenic temperatures. But CPAs become increasingly toxic as concentration increases. Many strategies have been attempted to overcome the problem of eliminating ice while minimizing toxicity, such as attempting to optimize cooling and warming rates, or attempting to optimize time of adding individual CPAs during cooling. Because strategies currently used are not adequate, CPA toxicity remains the greatest obstacle to cryopreservation. CPA toxicity stands in the way of cryogenic cryopreservation of human organs, a procedure that has the potential to save many lives. This review attempts to describe what is known about CPA toxicity, theories of CPA toxicity, and strategies to reduce CPA toxicity. Critical analysis and suggestions are also included.

Effect of high glucose concentrations on human erythrocytes in vitro

Exposure to high glucose concentrations in vitro is often employed as a model for understanding erythrocyte modifications in diabetes. However, effects of such experiments may be affected by glucose consumption during prolonged incubation and changes of cellular parameters conditioned by impaired energy balance. The aim of this study was to compare alterations in various red cell parameters in this type of experiment to differentiate between those affected by glycoxidation and those affected by energy imbalance. Erythrocytes were incubated with 5, 45 or 100 mM glucose for up to 72 h. High glucose concentrations intensified lipid peroxidation and loss of activities of erythrocyte enzymes (glutathione S-transferase and glutathione reductase). On the other hand, hemolysis, eryptosis, calcium accumulation, loss of glutathione and increase in the GSSG/GSH ratio were attenuated by high glucose apparently due to maintenance of energy supply to the cells. Loss of plasma membrane Ca²⁺-ATPase activity and decrease in superoxide production were not affected by glucose concentration, being seemingly determined by processes independent of both glycoxidation and energy depletion. These results point to the necessity of careful interpretation of data obtained in experiments, in which erythrocytes are subject to treatment with high glucose concentrations in vitro.

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Erythrocytes were incubated for up to 72 h in 5 mM, 45 mM and 100 mM glucose.

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High glucose concentrations intensified lipid peroxidation.

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High glucose attenuated hemolysis, eryptosis, Ca²⁺ accumulation and glutathione loss.

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Glucose is a glycating agent but also energy source.

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Results of exposure to high glucose should be interpreted with care.

Effect of metformin on the fertilizing ability of mouse spermatozoa

Numerous antioxidants have been added to cryopreservation media with varied success. The biguanide, metformin, commonly used for the treatment of type II diabetes, possesses properties impacting metabolism control that have not been yet assessed in cryopreservation protocols. The aim of this experiment was to; (i) determine the effect of metformin on fresh spermatozoa properties; and (ii) to assess positive or negative effects of metformin in post-thaw function and fertilizing capacity of mouse spermatozoa when used in cryopreservation media. The experiments have shown that the presence of metformin in fresh semen did not induce negative effects on spermatozoa quality, except a slight reduction in sperm motility at 5000μM metformin. However, when metformin was included in a cryopreservation protocol, an improvement in the fertilization rate and a reduction in the percentage of abnormal zygotes after in vitro fertilization was observed. In conclusion, metformin did not affect sperm quality at low concentrations (50μM), but its presence in the cryopreservation media could represent a benefit to improve the quality of frozen semen.

Suprazero cooling rate, rather than freezing rate, determines post thaw quality of rhesus macaque sperm

Sperm become most sensitive to cold shock when cooled from 37 °C to 5 °C at rates that are too fast or too slow; cold shock increases the susceptibility to oxidative damage owing to its influence on reactive oxygen species (ROS) production, which are significant stress factors generated during cooling and low temperature storage. In addition, ROS may be a main cause of decreased motility and fertility upon warming. They have been shown to change cellular function through the disruption of the sperm plasma membrane and through damage to proteins and DNA. The objective of this study was to determine which cryopreservation rates result in the lowest degree of oxidative damage and greatest sperm quality. In the rhesus model, it has not been determined whether suprazero cooling or subzero freezing rates causes a significant amount of ROS damage to sperm. Semen samples were collected from male rhesus macaques, washed, and resuspended in TEST-yolk cryopreservation buffer to 100 × 10(6) sperm/mL. Sperm were frozen in 0.5-mL straws at four different combinations of suprazero and subzero rates. Three different suprazero rates were used between 22 °C and 0 °C: 0.5 °C/min (slow), 45 °C/min (medium), and 93 °C/min (fast). These suprazero rates were used in combination with two different subzero rates for temperatures 0 °C to -110 °C: 42 °C/min (medium) and 87 °C/min (fast). The different freezing groups were as follows: slow-med (SM), slow-fast (SF), med-med (MM), and fast-fast (FF). Flow cytometry was used to detect lipid peroxidation (LPO), a result of ROS generation. Motility was evaluated using a computer assisted sperm motion analyzer. The MM and FF treated sperm had less viable (P < 0.0001) and motile sperm (P < 0.001) than the SM, SF, or fresh sperm. Sperm exposed to MM and FF treatments demonstrated significantly higher oxidative damage than SM, SF, or fresh sperm (P < 0.05). The SM- and SF-treated sperm showed decreased motility, membrane integrity, and LPO compared with fresh semen (P < 0.001). Slow cooling from room temperature promotes higher membrane integrity and motility post thaw, compared with medium or fast cooling rates. Cells exposed to similar cooling rates with differing freezing rates were not different in motility and membrane integrity, whereas comparison of cells exposed to differing cooling rates with similar freezing rates indicated significant differences in motility, membrane integrity, and LPO. These data suggest that sperm quality seems to be more sensitive to the cooling, rather than freezing rate and highlight the role of the suprazero cooling rate in post thaw sperm quality.