Rafał Strzeżek

Characteristics of spermatozoa of whole ejaculate and sperm-rich fraction of dog semen following exposure to media varying in osmolality

This study aimed to analyze the effects of different osmolalities on the characteristics of spermatozoa originating from whole ejaculates (WE; including the prostatic fluid) and the sperm-rich fractions (SRF). Ejaculates, collected from four mixed-breed dogs, were exposed for 10 min at room temperature to Tris-fructose-citrate (TFC) solution with osmolality ranging from 150 to 1100 mOsm. After treatment spermatozoa were evaluated by microscopic analysis of motility and fluorescent assessments of plasma membrane integrity (carboxyfluorescein diacetate and propidium iodide, CFDA/PI) and mitochondrial function (rhodamine 123, R123). Irrespective of the sperm source, there was a complete loss of motility when spermatozoa were exposed to TFC solution with 1100 mOsm. There were no marked differences in the sperm characteristics between media with 300 and 350 mOsm, regardless of the ejaculate collection procedure. However, a marked reduction in motility of spermatozoa retrieved either from the WE or SRF was observed after exposure to different anisosmotic conditions (150, 550 and 800 mOsm). In all dogs, spermatozoa from the WE exhibited greater osmotolerance in terms of plasma membrane integrity and mitochondrial function when exposed to anisosmotic conditions (150, 550, 800 and 1100 mOsm). There were inter-dog variations in response to various osmotic conditions. The findings of this study indicated that spermatozoa from the WE tolerated exposure to a wider range of osmolality than those from the SRF. It seemed that the presence of prostatic fluid of dog semen rendered the sperm membrane structures less susceptible to osmotic stress.

Effect of seminal plasma zinc–binding proteins on motility and membrane integrity of canine spermatozoa stored at 5°C

Abstract Sperm surface binding sites for non-zinc-binding proteins (nZnBPs) and zinc-binding proteins (ZnBPs) were studied by the fluorescence technique with biotin-labelled proteins. The nZnBPs binding pattern was unspecific, no characteristic sites on plasmalemma were found. ZnBPs were attached mainly to the acrosomal region of sperm head and to the sperm flagellum. ZnBPs added to the incubation mixture of the canine spermatozoa allowed the preservation of higher values for total motility, progressive motility, curvilinear line velocity, straight line velocity, and beat cross frequency (P < 0.05), both at time 0 and after 1 h incubation at 5ºC. The addition of nZnBPs to the incubation mixture caused only weak positive effects when compared with control sample (PBS). A higher percentage of canine-ejaculated spermatozoa with intact membranes were observed when ejaculate was incubated with ZnBPs in comparison to control sample stored with PBS (P < 0.05) or nZnBPs (P < 0.05). Spermatozoa diluted with ZnBPs and nZnBPs exhibited a higher percentage of cells with active mitochondria when compared with control, both at time 0 and after 1 h; however, no statistical differences were observed. Our results emphasise the role of seminal plasma protein in securing the correct quantity and availability of zinc ions as a component regulating the motility of canine spermatozoa. The protective effect of ZnBPs against the cooling effect may be due to their ability of preventing sperm membrane damage.

Spectrophotometric Analysis of the Resazurin Reduction Test as a Tool for Assessing Canine Semen Quality

Abstract The resazurin reduction test (RRT) was subjected to spectrophotometric analysis to evaluate the quality of canine semen. Twenty four samples of canine semen were analysed. The absorption peaks for resazurin and resorufin were determined at 615 and 580 nm, respectively. The RRT ratio (RRTsperm-the ratio for samples containing spermatozoa, RRTplasma-the ratio for samples containing seminal plasma) was calculated by dividing the absorbance at 580 nm by the absorbance at 615 nm. Spearman’s correlation test was used to determine the significance of correlations between the analysed sperm parameters and the results of the resazurin reduction assay. The RRT ratio was highly correlated with sperm motility (r=0.68, P<0.01), progressive sperm motility (r=0.61, P<0.01), the subpopulation of cells with rapid velocity (r=0.72, P<0.01), and the subpopulation of cells with medium velocity (r= -0.54, P<0.05). A negative correlation was observed between the reducing capacity of seminal plasma vs. sperm with plasma membrane integrity (r= -0.60, P<0.01) and sperm with normal morphology (r= -0.58, P<0.01). The RRT test can be used as an additional tool for evaluation of the quality of canine semen.

Effects of the platelet-activating factor (PAF) supplementation on ATP content of cryopreserved bull spermatozoa (AI)

The aim of this study was to investigate the effect of PAF supplementation in semen extender on ATP content in cryopreserved bull spermatozoa used for artificial insemination at different time intervals. Cryopreserved semen was treated with different concentrations of PAF: 1×10-5M, 1×10-6M, 1×10-7M, 1×10-8M and 1×10-9M at 37°C. In the present work we showed that content of ATP in cryopreserved semen supplemented with 1×10-9M PAF was statistically significantly higher at 90 and 120 minutes of incubation in comparison to the control group (p≤0.05). Present study indicates the potential influence of PAF on ATP content in male spermatozoa via its protective role towards mitochondria metabolic activity.

Identification and characterization of non-phosphorylcholine-binding and phosphorylcholine-binding proteins of canine seminal plasma

Abstract Seminal plasma (SP) proteins participate in the process of fertilization by binding to the sperm membrane, particularly to the phosphorylcholine-containing lipids. This study aimed to identify and characterize non-phosphorylcholine-binding and phosphorylcholine-binding proteins (nPch- BPs and PchBPs, respectively) of canine SP. The nPchBPs and PchBPs were isolated from canine SP by affinity chromatography. Electrophoretic studies revealed that the nPchBPs and PchBPs occurred in their native state as high-molecular-weight aggregates. Immunofluorescent staining showed preferential binding of nPchBPs to the sperm acrosome membrane, whereas PchBPs coating was uniformly distributed on the sperm post-acrosomal membrane, mid-piece and tail regions. Analysis with mass spectrometry confirmed that canine prostate specific esterase (CPSE) is a component of the nPchBPs and PchBPs, which is implicated in key mechanisms of protein-coating on the sperm plasma membrane surface. In addition, proteins of known binding properties such as prostaglandin-H2 D-isomerase and lipocalin-like 1 protein, identified in canine SP, might have a specific role in the fertilization-associated processes.

Effect of extender supplementation with low-molecular-weight antioxidants on selected quality parameters of cryopreserved canine spermatozoa

Abstract Introduction The addition of low-molecular-weight antioxidants during the freezing process improves post-thaw sperm quality. The high antioxidant potential of cryopreserved semen could have a positive effect on the motility, viability, and energy status of sperm cells and their ability to bind to the zona pellucida of oocytes. The aim of the study was to determine the effects of different concentrations and combinations of vitamins E and C in a semen extender on selected quality parameters of frozen-thawed canine spermatozoa. Material and Methods The experimental material was the semen of four mixed-breed dogs. Sperm viability (motility, plasma membrane integrity, and mitochondrial function) was examined at 0, 60, and 120 min in semen samples supplemented with the extender and in the controls. Results Combined supplementation with vitamins C + E at a concentration of 200 + 200 μM /1 × 109 spermatozoa had the most profound effect on total sperm motility, linear motility, and the percentage of spermatozoa with intact plasma membrane and active mitochondria. Conclusion The synergistic activity of vitamins E and C had a more beneficial influence on the quality of frozen–thawed sperm than these non-enzymatic antioxidants applied separately.

Effect of ostrich egg lipoproteins and hen egg yolk on the quality of dog sperm during liquid storage at 5 °C

Abstract The objective of this study was a comparative analysis of the impact of the addition of lipoproteins from ostrich egg yolk (LPFo) and hen egg yolk (HEY) to a Tris-citric acid-fructose (TCF) extender on the quality of dog sperm preserved at 5°C for 7 days. The sperm-rich fraction of the ejaculate was manually collected and extended using the following extenders: control (TCF), TCF+ 5% addition of LPFo (TCF-LPFo) and TCF+ 20% of addition HEY (TCF-HEY). The analysis of quality included: sperm motility parameters (TMOT, PMOT, VAP, VSL, VCL, ALH, BCF, STR, LIN), normal apical ridge acrosome (NAR), plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), and ATP content. The addition of LPFo and HEY to the TCF extender had a beneficial effect on all quality parameters of the stored sperm compared with the TCF extender. However, the analysis of sperm motility parameters revealed differences (P≤0.05) between TCF-LPFo and TCF-HEY extenders as affected by storage day. Semen extended in TCF-LPFo was characterized by lower values of TMOT and VAP on Day 5 and by lower values of TMOT and VCL on Day 7, compared to that extended in TCF-HEY. The analysis of PMOT, VSL, ALH, BCF, STR, LIN, PMI, MMP and ATP content showed no differences (P≥0.05) between TCF-LPFo and TCF-HEY extenders. The results suggest that TCF extender supplementation with LPFo or HEY improves the quality of dog sperm stored at 5°C. Both LPFo and HEY protect motility, membrane integrity and can contribute to the improvement of the energy status of stored dog sperm. LPFo can be alternatively used instead of HEY for dog semen preservation in the liquid state.

Effects of storage in different semen extenders on the pre-freezing and post-thawing quality of boar spermatozoa

The aim of this study was to investigate the effects of storage of semen in different commercial extenders on the pre-freezing and post-thawing quality of boar spermatozoa. Semen was diluted in BTS, Androhep (AH) and Gedil (GD), stored for 24 h at 17°C, and then frozen in accordance with the cryopreservation protocol. Analyses of the quality of spermatozoa included: motility, normal apical ridge (NAR) acrosome, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), measurements of ATP content and activity of superoxidase dismutase (SOD) and glutathione peroxidase (GPx). Prior to the freezing process, no significant effect of the extender on the sperm quality parameters was noted. After thawing the spermatozoa it was demonstrated that the type of extender used influenced PMI, MMP, ATP content and activity of GPx. In the AH extender the percentage of spermatozoa with PMI and ATP content in spermatozoa was significantly higher (P<0.05) as compared to the BTS or GD extenders. In addition, semen stored in the AH was characterised by a statistically higher (P<0.05) percentage of spermatozoa with MMP and increased activity of GPx as compared with the BTS. The results obtained indicate that for the cryopreservation process, boar spermatozoa stored for 24 hours in liquid state can be used. However, the type of extender used prior to freezing may have a significant effect on the post-thawing quality of the spermatozoa. The AH extender better secured the quality of thawed boar spermatozoa as compared with the BTS or GD.

Effect of dialysis of dog semen on sperm characteristics and some biochemical components of seminal plasma

The aim of this study was to investigate the effect of dog semen dialysis on sperm characteristics and some biochemical components of seminal plasma. Whole ejaculates were dialyzed against Tris-citrate-fructose extender for a 5 h period at room temperature (using semi-permeable cellulose tubing of 12-14 kDa molecular weight cut-off). It has been demonstrated that the long-term dialysis of dog semen causes a significant decrease in sperm quality parameters and disrupts the biochemical properties of seminal plasma. This procedure requires further improvement.

The effect of two packaging systems on the post-thaw characteristics of canine sperm

The aim of this study was to compare the effect of different packaging systems on some parameters of cryopreserved canine spermatozoa. The experimental material consisted of the sperm-rich fractions of ejaculates collected from four Beagle dogs. Semen samples for cryopreservation were stored in 0.25 ml plastic straws and two aluminum tubes with a total volume of 5.0 ml. Semen was frozen in static nitrogen vapor for 10 minutes (0.25 ml straws) or 15 and 20 minutes (aluminum tubes). Post-thaw assessments involved the determination of sperm motility parameters using a computer assisted sperm analyzer (CASA), sperm plasma membrane integrity (SPMI), mitochondrial membrane potential (MMP) and acrosome integrity (normal apical ridge, NAR). Regardless of the packaging system applied, no significant differences in total sperm motility (TMOT) or selected kinematic parameters were observed after freezing-thawing. However, spermatozoa frozen in 0.25 mL straws were characterized by improved functionality, in particular mitochondrial function, after thawing. The results indicate that large quantities of canine semen can be frozen in aluminum tubes. Further studies are required, however, to evaluate different freezing and thawing rates of aluminum tubes.