Semen plasma proteins prevent cold-shock membrane damage to ram spermatozoa

Seminal plasma removal for medium-term preservation of ram sperm at 5 °C

This study aimed to investigate if washing ram sperm from seminal plasma (SP) could be an effective tool to extend sperm lifespan in medium-term preservation in liquid form to optimize ovine artificial insemination protocols. To this end, in Experiment 1 SP was added to a sperm model without previous contact with this substance (ram epididymal sperm) at the beginning or the end of a 48-hour preservation protocol at 5 °C (n = 13). Sperm motility and kinetic parameters and sperm functionality in terms of sperm viability, apoptosis, mitochondrial activity and reacted acrosomes were assessed after 6 h of storage at 15 °C (standard liquid preservation method) and 24 and 48 h at 5 °C. Extended sperm showed better results after 48 h when stored in the absence than in the presence of SP in most sperm quality parameters. Moreover, the final SP supplementation of this experimental group resulted in the highest sperm motility and kinetic parameters, viability and mitochondrial activity. These results suggested that initial SP deprivation could be beneficial in a medium-term ram sperm preservation protocol in liquid form, as well as a final supplementation. Therefore, we conducted Experiment 2 to evaluate the effect of SP removal from freshly ejaculated ram semen under the same storage conditions as in Experiment 1 (n = 12). Surprisingly, SP withdrawal impaired sperm functionality, leading to increased apoptosis and decreased mitochondrial activity after 24 and 48 h at 5 °C. Conversely, SP supplementation at the end of the preservation protocol of the ejaculate processed as usual had a positive effect on sperm quality and fertility. To summarize, SP absence was beneficial for a medium-term preservation protocol (up to 48 h at 5 °C) of ram epididymal sperm, but the same preservation protocol for ram ejaculated sperm revealed a possible failure of the SP removal method in avoiding the sperm-SP interaction effect. Meanwhile, SP supplementation of ram semen at the end of the preservation protocol increased in vitro sperm quality and fertility after artificial insemination.

The association of resveratrol and AFPI did not enhance the cryoresistance of ram sperm

Cryoprotectants are required to reduce damage caused to the cells due to low temperatures during the cryopreservation. Antifreeze proteins (AFP) have a well-known role in cell membrane protection, while resveratrol is a potent antioxidant. This study assessed the effect of the association of resveratrol concentrations and AFP I in a ram semen extender. Pooled semen of four rams was allocated into six treatments in a factorial arrangement: (CONT, only the semen extender); only AFP I (ANT: 0.1 µg/mL of AFP I), only resveratrol, one treatment with two levels (10 µM/mL or 50 µM/mL of resveratrol); and two treatments with the interactions, with one AFP I and one of the two levels of resveratrol (0.1 µg/mL of AFP I with 10 µM/mL resveratrol; 0.1 µg/mL of AFP I with 50 µM/mL resveratrol). No interaction between factors was observed on sperm kinetics, plasma membrane integrity, hypo-osmotic test, and mitochondrial activity parameters. There was a high probability (P = 0.06) of reducing sperm cells with functional membrane percentage in the hypo-osmotic test and increasing the percentage of sperm with high mitochondrial activity (P = 0.07) was observed in AFP presence. An interaction of AFP and resveratrol was observed in non-capacitated sperm (P = 0.009), acrosomal reaction (P = 0.034), and sperm binding (P = 0.04). In conclusion, the association of resveratrol and AFP did not improve the quality of frozen-thawed semen and even promoted deleterious effects compared to their single addition in the semen extender. The supplementation of 50 µM/mL of resveratrol improved the outcomes of frozen-thawed ram sperm, being a potential cryoprotectant.

Advances in sperm cryopreservation in farm animals: Cattle, horse, pig and sheep

Sperm cryopreservation is one of the most important procedures in the development of biotechnologies for assisted reproduction. In some farm animals, the use of cryopreserved sperm has so many benefits for which relevance has become more evident in recent decades. Values for post-thaw sperm quality, however, are variable among species and within individuals of the same species. There is no standardized methodology for each of the stages of the cryopreservation procedure (andrological examination, semen collection, dilution, centrifugation, resuspension of the pellet with the freezing medium, packaging, freezing and post-thaw sperm evaluation), which also contributes to differences among studies. Cryotolerance markers of sperm and seminal plasma (SP) have been evaluated for prediction of ejaculate freezability. In addition, in previous research, there has been a focus on supplementing cryopreservation media with different substances, such as enzymatic and non-enzymatic antioxidants. In most studies, inclusion of these substances have led to improved post-thaw sperm quality and fertilizing capacity as a result of minimizing the adverse effects on sperm structure and function. Another approach is the use of different cryoprotectants. The aim with this review article is to provide an update on sperm cryopreservation in farm animals. The main detrimental effects of cryopreservation are described, including the negative repercussion on reproductive performance. Furthermore, the potential use of molecular biomarkers to predict sperm cryotolerance is discussed, as well as the addition of substances that can mitigate the harmful impact of freezing and thawing on sperm.

Seminal Plasma: Relevant for Fertility?

Seminal plasma (SP), the non-cellular component of semen, is a heterogeneous composite fluid built by secretions of the testis, the epididymis and the accessory sexual glands. Its composition, despite species-specific anatomical peculiarities, consistently contains inorganic ions, specific hormones, proteins and peptides, including cytokines and enzymes, cholesterol, DNA and RNA-the latter often protected within epididymis- or prostate-derived extracellular vesicles. It is beyond question that the SP participates in diverse aspects of sperm function pre-fertilization events. The SP also interacts with the various compartments of the tubular genital tract, triggering changes in gene function that prepares for an eventual successful pregnancy; thus, it ultimately modulates fertility. Despite these concepts, it is imperative to remember that SP-free spermatozoa (epididymal or washed ejaculated) are still fertile, so this review shall focus on the differences between the in vivo roles of the SP following semen deposition in the female and those regarding additions of SP on spermatozoa handled for artificial reproduction, including cryopreservation, from artificial insemination to in vitro fertilization. This review attempts, including our own results on model animal species, to critically summarize the current knowledge of the reproductive roles played by SP components, particularly in our own species, which is increasingly affected by infertility. The ultimate goal is to reconcile the delicate balance between the SP molecular concentration and their concerted effects after temporal exposure in vivo. We aim to appraise the functions of the SP components, their relevance as diagnostic biomarkers and their value as eventual additives to refine reproductive strategies, including biotechnologies, in livestock models and humans.

Influence of seminal plasma during different stages of bovine sperm cryopreservation

This study aimed to evaluate the effect of seminal plasma on bovine sperm cryopreservation and to assess the integrity of plasma and acrosomal membranes, mitochondrial potential, remodelling of F-actin cytoskeleton and sperm chromatin fragmentation during the cooling, equilibrium and freezing/thawing stages. Six ejaculates collected from seven Nelore bulls (n = 42) were used in this study. Each ejaculate was divided into two aliquots (with seminal plasma = SP group; without seminal plasma = NSP group) and packed to a final concentration of 50 × 10⁶ sperm per straw. Statistical analyses were performed using SAS software (version 9.3), and p ≤ .05 was considered significant. A time effect was observed for all sperm characteristics (p < .05), except for chromatin fragmentation (p > .05). The presence of seminal plasma better preserved the acrosomal integrity (SP = 75.2% and NSP = 71.7%; p < .05) and also provided lower F-actin remodelling during cryopreservation process (SP = 29.9% and NSP = 32.4%; p < .05). Regarding to the cryopreservation stages, it was observed that cooling step induced higher remodelling of F-actin than the equilibrium and freezing/thawing stages (56.3%, 32.2% and 23.9%, respectively; p < .05). The equilibrium step had minor influence on overall sperm characteristics while the freezing/thawing stage was responsible for the highest percentage of damage in plasma membrane (-65.2%), acrosomal membrane (-34.0%) and mitochondrial potential (-48.1%). On the other hand, none of the cryopreservation stages affected chromatin integrity. It was concluded that the presence of seminal plasma provides increased acrosomal integrity and reduced remodelling of F-actin cytoskeleton. Higher F-actin remodelling is observed after the cooling step while the freezing/thawing step is most damaging to sperm membranes and mitochondrial potential during bovine sperm cryopreservation.

Effects of Dietary Supplementation of Conjugated Linoleic Acids and Their Inclusion in Semen Extenders on Bovine Sperm Quality

Simple Summary

Suboptimal fertility in males accounts for about two-thirds of infertility cases, thus being of serious concern for the dairy industry, where optimal fertility is fundamental for farm profitability. Although genetic defects responsible for subfertility have been identified, the role of seminal compounds on fertility remain unclear. Feeding rumen-protected isomers of conjugated linoleic acid (CLA) to dairy cows reportedly enhances circulating insulin-like growth factor I (IGF-I) levels. In breeding bulls, the IGF-I concentration in seminal plasma has been positively correlated with fertility rates. Therefore, the objective of the study was to evaluate the effect of dietary CLA supplementation and of their inclusion to the semen extender on bovine semen quality and freezability.

Abstract

Isomers of conjugated linoleic acid (CLA) enhances circulating insulin-like growth factor I (IGF-I) levels. Furthermore, fertility rate of breeding bulls is positively correlated to seminal plasma IGF-I concentration. Our objective was to evaluate the effect of dietary CLA supplementation and inclusion to the semen extender on bovine semen quality and freezability. Fourteen bulls, randomly assigned to control (CTL) and CLA (50 g/day) groups, were supplemented for 10 weeks. Samples were collected at Weeks −2 (before supplementation), 0, 4, 6 (during supplementation), 10, and 11 (after supplementation). Blood and seminal plasma were analyzed for IGF-I; the ejaculates were frozen in the following subgroups: CTL (no addition to semen extender), CLA c9, t11 (50 µM), CLA c9, t11 (100 µM), CLA t10, c12 (50 µM), CLA t10, c12 (100 µM), and CLA mix (50 µM each of CLA c9, t11 and CLA t10, c12). Sperm motility, morphology, viability, mitochondrial membrane potential, and reactive oxidative species were assessed. CLA supplementation decreased ejaculates’ total volume, increased sperm concentration, beat cross frequency, and decreased oxidative stress; it also increased plasma and seminal plasma IGF-I levels compared to the CTL. The inclusion of CLA c9, t11 100 µM and CLA mixture in the extender increased live spermatozoa percentage post-thawing compared to other groups. Our results show a beneficial effect of CLA supplementation on semen quality; however, further studies evaluating fertilization rates are necessary to corroborate the results.

Influence of Season and Liquid Storage at 16 °C on Beni Arouss Bucks' Semen Quality

Simple Summary

Goat production plays an important economic and social role in Northern Moroccan farming. Beni Arouss is an autochthonous North Moroccan goat breed. The use of artificial insemination can largely contribute to optimised preservation and dissemination of valuable traits of this breed and lead to improved productivity. During liquid storage, the stability of semen good quality remains crucial in order to provide greater flexibility between the artificial insemination center and farms where the insemination of does needs to be performed. The study aims to assess the effect of storage and season of the year on fresh semen of Beni Arouss goats. Every month, ejaculates were collected from bucks and were extended and stored at 16 °C for 24 h. Semen motility, viability and normal morphology were assessed at 0, 4, 8 and 24 h after collection. As expected, these parameters showed a significant reduction within 24 h of storage and during all seasons. However, semen collected in summer maintained a better quality after 24 h of storage at 16 °C than semen collected during the other periods. Therefore, the storage ability of Beni Arouss bucks’ semen stored at 16 °C was higher during the summer.

Abstract

The study aimed at determining the effect of storage and season on fresh semen of Beni Arouss goats. Ejaculates were collected at monthly intervals from seven mature bucks and were extended at a final concentration of 800 × 10⁶ spermatozoa. ml^-1 and stored at 16 °C for 24 h. Semen motility, viability and normal morphology were assessed at 0, 4, 8 and 24 h after collection. Motility and normal morphology parameters were recorded using computer-assisted sperm analysis (CASA) and viability was analyzed using eosin–nigrosin staining. As expected, motility, viability and normal morphology parameters showed a significant reduction within 24 h of storage and during all seasons (p < 0.05). However, semen collected in summer maintained a better quality after 24 h of storage at 16 °C than semen collected during the other periods (p < 0.05). In conclusion, the storage ability of Beni Arouss bucks’ semen stored at 16 °C was significantly higher during the summer.

Ram seminal plasma and its functional proteomic assessment

Ejaculation results in the confluence of epididymal spermatozoa with secretions of the accessory sex glands. This interaction is not a prerequisite for fertilisation success, but seminal factors do play a crucial role in prolonging the survival of spermatozoa both in vitro and in vivo by affording protection from handling induced stress and some selective mechanisms of the female reproductive tract. Reproductive biologists have long sought to identify specific factors in seminal plasma that influence sperm function and fertility in these contexts. Many seminal plasma proteins have been identified as diagnostic predictors of sperm function and have been isolated and applied in vitro to prevent sperm damage associated with the application of artificial reproductive technologies. Proteomic assessment of the spermatozoon, and its surroundings, has provided considerable advances towards these goals and allowed for greater understanding of their physiological function. In this review, the importance of seminal plasma will be examined through a proteomic lens to provide comprehensive analysis of the ram seminal proteome and detail the use of proteomic studies that correlate seminal plasma proteins with ram sperm function and preservation ability.

Conjugated linoleic acid as a potential bioactive molecule to modulates gamete and embryo cryotolerance

Abstract Conjugated linoleic acid (CLA) is a mixture of positional isomers of linoleic acid found in meat and dairy products from ruminants. It is a trans fat widely used by athletes as a food supplement, due to a supposed effect of maximizing the use of body fat reserves. The interest in diet and culture media supplementation with CLA is an emerging area, demanding studies in order to elucidate its benefits in the reproductive parameters, as well as in cryopreservation. Therefore, the aim of this review was to discuss the effects of CLA on the oocytes, sperm and embryos cryotolerance. Some studies have already demonstrated its use in cryopreservation of germline. Among those, it was observed that CLA supplementation during oocyte in vitro maturation can increase their viability post-freezing and developmental capacity. Regarding the use of CLA on sperm, there are few studies and their results are still inconclusive. Finally, studies about CLA supplementation on embryo culture media have shown promising results, indicating that this bioactive molecule is able to modulate lipid uptake on blastomeres. Altogether, these findings demonstrate the potential use of CLA as a bioactive molecule to improve germline and embryo cryotolerance and open new perspectives on human and animal reproduction field.

Homologous Seminal Plasma and Glutathione Promote Pre-Capacitation Motility and Structural Stability of Cryopreserved Ram Spermatozoa

Reduced glutathione (GSH) and homologous ram seminal plasma (HSP), used as additives in cryopreserving (CP) media prior to freezing, showed conflicting results in retaining structural integrity and progressive motility in post-thawed ram spermatozoa. The aims of this research were: (1) to assess the effect of GSH and/or HSP supplementation via soybean-lecithin CP extender on cryopreserved ram spermatozoa viability, morphology and motility pattern; and (2) to assess the effect of incubation in the context of the previous aim. Quantitatively and qualitatively, homogenized and pooled ram ejaculates (N=10) were extended with one of the following extenders: control (C) – tris-based, GSH and HSP-free, experimental-1 (E1) – C + GSH 5 mM, experimental-2 (E2) – C + HSP 20 % and experimental-3 (E3) - GSH 5 mM + HSP 20 %. Following thawing, samples were taken at 0- and 3-hours from each group (n=10) and were assessed for spermatozoa viability, morphology, and motility pattern. C-0h samples yielded a spermatozoa population with low viability, altered head morphology and highly deviated motility pattern. E3-3h samples yielded spermatozoa with unaffected viability, head morphology and high progressive motility. In conclusion, E3 extender added to cryopreserved-thawed ram spermatozoa is most efficient in obtaining high viability, unaltered head morphology, and progressive motility.

Recombinant peptide reverses cryo-capacitation in ram sperm and improves in vitro fertilization

Semen cryopreservation is a very important technique for assisted reproduction; however, the cryopreservation process is harmful because it results in a reduction in sperm motility and viability, and leads to premature signals of capacitation, resulting in lesser than desirable fertility rates after artificial insemination. A fraction of seminal plasma, enriched in proteins that contain type II fibronectin domains (FNII) can reverse molecular indicators of cryo-capacitation. The beneficial effects of these proteins, however, depend on the relative abundance in seminal plasma. To create a safe additive for improving frozen sperm functionality, in the present study there was cloning and expression of a recombinant peptide containing four FNII domains (named TrxA-FNIIx4-His6) and evaluation of its effect after addition to frozen/thawed ram sperm. The cDNA for this protein was expressed in E. coli and after denaturation and re-naturalization of the protein, toxicity and binding capacity were assessed. By fluorescent labelling assessment, there was binding of the protein to the thawed sperm. At the two doses used (0.15 and 0.3 μM), TrxA-FNIIx4-His6 had the capacity to reverse the molecular indicators of cryo-capacitation as indicated by the reduction on phosphorylated substrates of PKA. Furthermore, the supplementation with this protein resulted in a normal capacitation process as evidenced by the increase in the in vitro fertilization rate when the greatest concentration of the protein was evaluated (73.25 ± 2.95; 40.13 ± 11.82 for 0.3 μM and control, respectively). There was no effect of protein supplementation on sperm objective motility compared to untreated sperm. In conclusion, the use of TrxA-FNIIx4-His6 is a promising biotechnological approach for cryopreserving ram sperm and maintaining sperm viability.

The influence of dietary sunflower oil, rich in n-6 polyunsaturated fatty acids, in combination with vitamin C on ram semen parameters, sperm lipids and fertility

BACKGROUND

Dietary fats, fed to ruminant animals, have been observed to improve reproductive function. Sunflower oil is one of the richest sources of polyunsaturated fatty acids (PUFAs), over 60% of which is linoleic acid (C18:2). With regard to recommendations for increased consumption of PUFAs, special emphasis has been given to the importance of consuming more antioxidants to prevent lipid peroxide formation. This study evaluated the effects of dietary n-6 PUFAs and vitamin C (VC) in rams - in particular, on semen quality, blood metabolites, sperm lipids and overall fertility.

RESULTS

Diets supplemented with SFO and VC increased the proportion of motile sperms and their progressive motility improved (P < 0.01). Rams fed a diet containing SFO had an increased proportion of sperms with normal acrosomes in their semen samples (P < 0.01). The highest levels of lactate dehydrogenase activity (LDH) enzyme were found in control rams (2.60 U mL^-1 ). Feeding SFO significantly affected blood triglyceride and cholesterol concentrations (P < 0.05). Diets containing SFO increased the proportion of C18:2c, C20:4, C20:3 and C22 in the sperm lipid composition (P < 0.05). Semen of SFO and VC-fed rams was more fertile than that of control rams when it was artificially inseminated to ewes.

CONCLUSION

Feeding rams with supplemental SFO and VC increased semen quality and improved fertility rates. © 2019 Society of Chemical Industry.

In vitro supplementation with unsaturated fatty acids improves boar sperm viability after storage at 6 °C

Liquid preservation of the cold-sensitive boar sperm at a lesser temperature than the standard 17 °C would reduce bacterial growth and minimize the use of antibiotics. There was assessment, therefore, of the capacity of individual fatty acids bound to fatty acid free BSA to improve sperm survival at 6 °C because oxidative stress and lipid degradation are prominent detrimental factors. Different effects of the fatty acids were observed. Supplementation with naturally occurring fatty acids (linolenic, linoleic, oleic, palmitoleic acid), which may become metabolically incorporated into sperm lipids, increased the number of motile and progressively motile sperm after 2 days of storage during a thermo-resistance test (5 h at 38 °C) to that of control samples preserved at 17 °C in pure Beltsville Thawing Solution. With the exception of linolenic acid, all naturally occurring fatty acids enhanced the number of sperm with active mitochondria after 3 days of storage. Palmitoleic acid was the most effective supplement with effects already present when sperm were re-warmed for 30 min after 2 and 7 days of storage. The non-endogenous, non-integrated timnodonic acid (20:5) had no effect on sperm variables. Because the application of individual fatty acids attached to BSA had differing effects in preserving boar sperm at 6 °C, the use of combinations of fatty acids could be more efficacious than with use of natural lipid supplements for low temperature preservation of sperm.

Seminal plasma amino acid profile in different breeds of chicken: Role of seminal plasma on sperm cryoresistance

Seminal plasma is a key biological fluid that modulates sperm function in the reproduction process. However, its role in sperm biotechnologies is scarce in poultry. The aims of the present study were to study the amino acids profile and total proteins of seminal plasma in 12 Spanish chicken breeds and to investigate the role of seminal plasma on cryoresistance of rooster sperm. To investigate the role of seminal plasma on cryoresistance, diluted pooled semen samples were cryopreserved in the presence and absence of seminal plasma. Glutamic acid was the most abundant free amino acid in seminal plasma, followed by alanine, serine, valine, and glycine. There was an influence of breed (P<0.05) on the percentage of viable sperm after freezing-thawing of samples with seminal plasma. Cluster analysis revealed that White Prat, Black Castellana, Blue Andaluza, Quail Castellana, and Red-Barred Vasca returned the best freezing-thawing response (good freezers). There was a positive correlation between seminal plasma concentrations of valine, isoleucine lysine, leucine and post thaw viability. The evaluation of fertilization capacity of frozen-thawed semen from the breeds White Prat ('good freezer') and Black-Red Andaluza ('bad freezer') showed that good freezer had higher fertility (20/68, 29.4%) compared to bad freezer breed (14/76, 18.4%), even if the difference was not significant (P = 0.08). The TUNEL assay revealed that freezing/thawing procedures in presence of seminal plasma provoked higher DNA fragmentation in most of the breeds, with a positive correlation between seminal alanine, valine, isoleucine, methionine, leucine, tyrosine, phenylalanine concentrations and DNA integrity. DNA fragmentation was lower in absence of seminal plasma and the breed effect on sperm viability was highly reduced. It is concluded that specific seminal plasma amino acids were associated with post-thaw percentage of viable sperm and DNA integrity. The removal of seminal plasma decreases the variability of the results and DNA fragmentation damages.

Effects of season and artificial photoperiod on semen and seminal plasma characteristics in bucks of two goat breeds maintained in a semen collection center

Aim:

This study quantified the effects of season and photoperiodic treatment on semen and seminal plasma (SP) characteristics in 12 bucks of two Spanish goat breeds (Murciano-Granadina, and Payoya) for the past 1 year.

Materials and Methods:

A total of 6 bucks (three of each breed) were exposed to the natural day length and the other six males (three of each breed) were exposed to alternating conditions of 2 months of long days (16 h light) and 2 months of short days (8 h light). Weekly concentrations of glutamic oxaloacetic transaminase/aspartate aminotransferase (GOT/AST), lactate dehydrogenase (LDH), potassium, testosterone, and protein in SP were measured. Reaction time and scrotal circumference were recorded, and plasma testosterone concentrations were measured before semen collection.

Results:

Sperm volume, LDH, and potassium concentration in SP, and reaction time did not differ significantly between breeds, seasons, and photoperiodic treatment. Sperm concentrations were higher (p<0.001) in spring and summer than they were in autumn and winter. Mean percentage of positive hypo-osmotic swelling test sperm was the highest in summer and under the artificial photoperiod (p<0.01). GOT/AST concentrations differed (p<0.01) between breeds and seasons. Breed, season, and photoperiod had significant (p<0.001) effects on protein and testosterone levels in SP. Plasma testosterone concentrations were highest in summer (p<0.001), and differed significantly (p<0.01) between breeds. Scrotal perimeter differed significantly (p<0.001) between breeds and photoperiod.

Conclusion:

Recognition of those seasonal and breed-specific differences in the performance of bucks should help to improve the management of individual semen samples for use in artificial insemination programs.

Physical evaluation, morphological and identification of seminal proteins in Santa Ines sheep

SUMMARY This study aimed to identify proteins in the seminal plasma associated with fertility in sheep of Santa Inês in Manaus, AM, using twodimensional electrophoresis techniques associated with mass spectrometry. Semen samples from eight adult sheep were collected by removing an aliquot for the physical and morphological assessments of semen and seminal plasma was subjected to SDS-PAGE profile and two-dimensional electrophoresis. Gels were stained with colloidal Coomassie, scanned and analyzed using ImageMaster 2D Platinum software, version 6.0. The selected individual spots were cut from the master gel, digested with trypsin and subjected to identification by mass spectrometry (MALDITof / Tof). Of the 108 spots detected in the gel, it selected 10 differential spots (based on the distribution thereof in the bidimensional gel and pre-analysis of the 2D ImageMaster Platinum Software) identifying 03 proteins: clusterin, a protein 14-3-3 zeta chain and Ram Seminal versicles 22kDa Protein. The identity of these proteins implies that the components of seminal plasma participate in physiological processes involved in sperm protection, motility and sperm capacitation, all associated with fertility. These proteins need to be better studied to see whether the same could be used as molecular markers of fertility as they were also found in other studies conducted with sheep Santa Ines.

Evaluation of the Efficiency of Two Different Freezing Media and Two Different Protocols to Preserve Human Spermatozoa from Cryoinjury

It is universally recognized that cryopreservation impairs sperm quality. In order to improve postthawing sperm survival and motility, media of different composition and different protocols have been proposed. However, no clear evidence is available to understand which are the most efficient protocol and medium for sperm cryopreservation. The present study evaluates the efficiency of two different cryopreservation protocols and two common freezing media (FM) containing different cryoprotectants (CPs), TEST Yolk Buffer (TYB) and Sperm Freeze (SF), to preserve human sperm quality. Our data suggest that TYB is better than SF both in terms of postthaw viability and in terms of progressive motility, while the direct addition of FM to the sperm sample resulted in the most efficient protocol in terms of postthaw viability but not in terms of progressive motility.

New Insights into the Phylogeny and Gene Context Analysis of Binder of Sperm Proteins (BSPs)

Seminal plasma (SP) proteins support the survival of spermatozoa acting not only at the plasma membrane but also by inhibition of capacitation, resulting in higher fertilizing ability. Among SP proteins, BSP (binder of sperm) proteins are the most studied, since they may be useful for the improvement of semen diluents, storage and subsequent fertilization results. However, an updated and detailed phylogenetic analysis of the BSP protein superfamily has not been carried out with all the sequences described in the main databases. The update view shows for the first time an equally distributed number of sequences between the three families: BSP, and their homologs 1 (BSPH1) and 2 (BSPH2). The BSP family is divided in four subfamilies, BSP1 subfamily being the predominant, followed by subfamilies BSP3, BSP5 and BSP2. BSPH proteins were found among placental mammals (Eutheria) belonging to the orders Proboscidea, Primates, Lagomorpha, Rodentia, Chiroptera, Perissodactyla and Cetartiodactyla. However, BSPH2 proteins were also found in the Scandentia order and Metatheria clade. This phylogenetic analysis, when combined with a gene context analysis, showed a completely new evolutionary scenario for the BSP superfamily of proteins with three defined different gene patterns, one for BSPs, one for BSPH1/BSPH2/ELSPBP1 and another one for BSPH1/BSPH2 without ELSPBP1. In addition, the study has permitted to define concise conserved blocks for each family (BSP, BSPH1 and BSPH2), which could be used for a more reliable assignment for the incoming sequences, for data curation of current databases, and for cloning new BSPs, as the one described in this paper, ram seminal vesicle 20 kDa protein (RSVP20, Ovis aries BSP5b).

Interaction of milk proteins and Binder of Sperm (BSP) proteins from boar, stallion and ram semen

BACKGROUND

Mammalian semen contains a family of closely related proteins known as Binder of SPerm (BSP proteins) that are added to sperm at ejaculation. BSP proteins extract lipids from the sperm membrane thereby extensively modifying its composition. These changes can ultimately be detrimental to sperm storage. We have demonstrated that bovine BSP proteins interact with major milk proteins and proposed that this interaction could be the basis of sperm protection by milk extenders. In the present study, we investigated if homologous BSP proteins present in boar, stallion and ram seminal plasma display a similar affinity for the milk proteins in order to assess whether the mechanism of sperm protection by milk for these species could be general.

METHODS

Skim milk was incubated with seminal plasma proteins (boar, stallion and ram), chromatographed on a Sepharose CL-4B column and protein fractions were analyzed by immunoblotting.

RESULTS

Boar, stallion and ram BSP proteins displayed affinity for a milk protein fraction (F1) mainly composed of α-lactalbumin, β-lactoglobulin, and κ-casein. They also had affinity for another milk protein fraction (F2) composed mostly of casein micelles. However, stallion BSP showed higher affinity for the fraction (F1).

CONCLUSIONS

These results further extend our view that the association of BSP proteins with milk proteins could be a general feature of the mechanism of mammalian sperm protection by milk to prevent detrimental effect of prolonged exposure of sperm to seminal plasma.

α-Tocopheryl Phosphate as a Bioactive Derivative of Vitamin E: A Review of the Literature

α-Tocopheryl phosphate (α-TP) is a naturally occurring derivative of α-tocopherol (α-T), one of the eight isoforms of vitamin E. α-TP is present at very low intracellular concentrations, traffics across plasma membranes, and affects many important cellular functions. In addition to being a signaling molecule, α-TP has also been shown to possess antioxidant and potentially antiatherosclerotic properties that are more potent than its parent compound (α-T). However, there is little published data on the clinical effects of α-TP supplements, the mechanisms involved in its metabolism and cellular function, and reliable methods for its determination in plasma.

Criopreservação do sêmen ovino em meio diluente à base de água de coco em pó (ACP-102c)

O objetivo deste trabalho foi avaliar o diluente ACP-102c na criopreservação do sêmen ovino em comparação com o diluidor tris-glicose-gema (TRIS) e o sêmen fresco. Foram coletados 48 ejaculados de quatro ovinos, sendo tomadas duas alíquotas por ejaculado para diluição e criopreservação em ACP-102c ou TRIS e uma terceira alíquota utilizada para análise do sêmen fresco. O sêmen fresco e o criopreservado em ambos os diluidores foram avaliados para viabilidade, integridade de membrana plasmática e acrossomal, teste hiposmótico, fragmentação do DNA e de motilidade espermática. Após descongelamento, ambos os diluidores não diferiram para viabilidade espermática, integridade de membrana plasmática e acrossomal, fragmentação de DNA e nas variáveis quantitativas e qualitativas de velocidade espermática, mas diferiram no teste hiposmótico, motilidade total e progressiva e amplitude lateral da cabeça, bem como em todas as variáveis de motilidade avaliadas, exceto linearidade e progressividade, após duas horas de incubação à 37 ºC. Houve variabilidade entre reprodutores na motilidade total e progressiva do sêmen criopreservado em ACP-102c após descongelamento. O diluidor ACP-102c conferiu menor proteção aos espermatozoides ovinos contra danos do congelamento quando comparado ao TRIS, mas o aprimoramento de sua formulação e protocolos mais adequados de congelação poderão torná-lo uma alternativa na congelação do sêmen ovino.

Effect of prostatic fluid on the quality of fresh and frozen-thawed canine epididymal spermatozoa

Canine epididymal spermatozoa have a low freeze-tolerance ability compared with ejaculated spermatozoa, which could arise from the absence of prostatic fluid (PF). Therefore, the purpose of this work was to elucidate the influence of PF on the quality of canine epididymal sperm before and after freezing. Caudae epididymides were retrieved from eight dogs after routine castration. Spermatozoa were released by slicing the tissue and were extended in either Tris solution or PF before freezing. Frozen sperm samples were thawed at 70 °C for 8 seconds in a waterbath. Sperm concentration, motility using computer-assisted sperm analysis, morphology, plasma membrane, acrosome and chromatin integrity were assessed in the fresh sperm samples (after 20 minutes incubation) and at 0 and 4 hours after thawing. Progressive motility, distance straight line, distance average path, average path velocity, curvilinear velocity, straight line velocity, straightness, linearity, wobble, and beat cross frequency were significantly increased after extraction into PF. There was a higher proportion of spermatozoa with DNA damage in the PF treatment group at 4 hours after thawing than in the Tris treatment group (15.8% vs. 6.7%, P < 0.05). These results suggest that the addition of PF to canine spermatozoa activates sperm motility in fresh spermatozoa but has a negative effect on chromatin integrity after freezing-thawing.

Alpaca semen quality in relation to different diets

The aim of the present study was to evaluate the biochemical composition of seminal plasma, along with semen quality, of alpacas maintained on different diets (hay; hay+pasture grazing; pasture grazing+sheep concentrate; pasture grazing+horse concentrate; Periods 1-4, respectively). Alpacas (n=5) were fed the four different diets for a period of 6 weeks each. During the period of feeding of each diet, semen was collected using an artificial vagina to determine its volume, viscosity, sperm concentration and sperm motility. Moreover, testicular volume and body condition score were evaluated. Seminal plasma was analysed biochemically to measure total protein, triglyceride, cholesterol, γ-glutamyl transferase, alanine aminotransferase (ALT) and alkaline phosphatase levels. Protein profiles were investigated using one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. There was high variability in semen parameters between different males maintained on the same diet. Semen volume increased significantly (P<0.05) when alpacas were fed diets containing commercial sheep and horse concentrates. In contrast, sperm concentration and motility decreased significantly (P<0.05) from Period 1 to Period 4. Dietary changes had no effect on viscosity. Significant reductions were seen in triglyceride and cholesterol content, as well as γ-glutamyl transferase, ALT and alkaline phosphatase concentrations, from Period 1 to Period 4. Regardless of experimental period, a wide variation was seen in seminal plasma enzyme concentrations between alpacas, whereas diet had no effect on glucose and total protein concentrations in the seminal plasma. Eight protein bands, with molecular weights ranging from 200 to 14kDa, were considered in electrophoresis gel after image analysis. Proteins fractions of the 14-kDa (total protein express in mddL(-1) with a molecular weight of 14-kDa, TP8) and 21-kDa (total protein express in mddL(-1) with a molecular weight of 21-kDa, TP7) bands were not present in all samples of alpaca seminal plasma. There were no significant changes in the concentration of any protein fractions during the four periods. Moreover, the protein fraction of the 60-kDa (total protein express in mddL(-1) with a molecular weight of 60-kDa, TP3) band was the most prevalent in all periods. These results demonstrate that there are marked changes in semen quality, as well as some parameters related to the composition of alpaca seminal plasma, that are dependent on diet, which may indicate the need for specific diet formulation to improve reproductive performance. We hypothesise that, in alpacas, the mechanisms underlying the changes in some reproductive traits in response to feeding regimens could be related to changes in the endocrine-gonadal system.

Effect of cis-9,trans-11 and trans-10,cis-12 isomers of conjugated linoleic acid on the integrity and functionality of cryopreserved bovine spermatozoa

Plasma membranes of sperm subjected to low temperatures undergo changes in their structure and permeability. The addition of fatty acids in semen cryopreservation media may influence the sperm motility after thawing, possibly by maintaining the membrane fluidity due to their incorporation in lipid bilayers. In this work, different concentrations of the isomers cis-9,trans-11 and trans-10,cis-12 of conjugated linoleic acid (CLA) were added in the cryopreservation medium of bovine sperm. Four Jersey bulls were used, and the ejaculates were processed as a pool. The Tris-based extender (Dilutris®) was supplemented with 20% egg yolk (MB). The treatments with CLA (Luta-CLA®), which had oily presentation, were prepared from MB with addition of 1% sodium lauryl sulfate, and denominated MBL. The concentrations of CLA tested were 50, 100, and 150 μM. The motility characteristics of the post-thaw semen were analyzed by computerized analysis system (CASA), and plasma membrane integrity and acrosomal and mitochondrial function assessed by the association of the fluorescent probes propidium iodide, fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA), JC-1 and Hoechst 33342. No significant differences were observed among treatments, excepting for a decreased mitochondrial potential of cells treated with 150 μM CLA. The addition of CLA, at the concentrations used, showed no advantages on the integrity and functionality of bovine sperm submitted to cryopreservation.

Seminal plasma and its effect on ruminant spermatozoa during processing

Seminal plasma can both inhibit and stimulate sperm function, making its use as a supportive medium somewhat contradictory. These effects are directed by the multifunctional action of numerous inorganic and organic components, but it is the direct association of seminal plasma proteins with the sperm membrane that is thought to exert the most significant response. In vitro handling of spermatozoa in preparation for artificial insemination may involve washing, dilution, cooling, freezing, re-warming and sex-sorting. These processes can alter proteins of the sperm surface and reduce seminal plasma in the sperm environment. This, among other factors, may destabilize the sperm membrane and reduce the fertilizable lifespan of spermatozoa. Such handling-induced damage may be prevented or reversed through supplementation of seminal plasma, but the effectiveness of this technique differs with species, and the source and subsequent treatment of both spermatozoa and seminal plasma. Seminal plasma appears to act as a protective medium during in vitro processing of ram spermatozoa, but this does not appear to be the case for bull spermatozoa. The reasons for this divergent effect will be discussed with particular emphasis on the influence of the major proteins of ruminant seminal plasma, known as BSP proteins. The biochemical and biophysical properties of these proteins are well documented, and this information has provided greater insight into the signalling pathways of capacitation and the protective action of extender components.