Sperm quality variables of sex-sorted bull semen produced by magnetic-activated cell sorting coupled with recombinant antibodies targeting Y-chromosome-bearing sperm

The immunological sexing method using antibodies offers cost-effective, high-volume production but faces challenges in terms of X-sperm purity in sexed semen. This research aimed to produce sexed bull semen using highly specific recombinant antibodies in magnetic-activated cell sorting (MACS), evaluate sperm quality and kinematic parameters, and verify the sex ratio of sperm, embryos, and live calves. Fresh semen from two Angus bulls was separated into two equal groups: conventional (CONV) semen and semen sexed using MACS with Y-scFv antibody conjugation to separate two fractions, i.e., the X-enriched and Y-enriched fractions. Then, computer assisted semen analysis and imaging flow cytometry were used to evaluate sperm motility and kinematic variables, acrosomal integrity, sperm viability, and sperm sex ratios. The results showed that sperm motility and quality did not differ between X-enriched and CONV semen. However, the Y-enriched fraction showed significantly lower sperm quality than the X-enriched fraction and CONV semen. The sperm ratio revealed that X-sperm accounted for up to 79.50% of the X-enriched fraction, while Y-sperm accounted for up to 78.56% of the Y-enriched fraction. The sex ratio of embryos was examined using in vitro fertilization. The cleavage rates using CONV and X-enriched semen were significantly higher than that using Y-enriched semen. Accordingly, 88.26% female blastocysts were obtained by using X-enriched semen, and 83.58% male blastocysts were obtained by using Y-enriched semen. In farm trials, 304 cows were subjected to AI using X-enriched and CONV semen. The pregnancy rate did not differ between the X-enriched and CONV semen groups. On the other hand, X-enriched semen generated significantly more live female calves (83.64%) than CONV semen (47.00%). The MACS sexing method significantly enhanced the X-sperm purity in sexed semen, producing high-quality sperm, a high percentage of female blastocytes, and a high percentage of live female calves.

Influence of Equilibration Time and Bull-Specific Extender for Cryopreservation on Semen Quality and Fertility in German Holstein Friesian Bulls: A Controlled Field Trial

Equilibration with an extender is necessary to allow cryopreservation of bovine sperm. The aim of trial 1 was to assess the effect of 24 h versus 4 h equilibration time with three different extenders on sperm quality and to select the preferred extender for each bull. The aim of trial 2 was to investigate the effect of using a 24 h equilibration time with a bull-specific extender on field fertility. For trial 1, three ejaculates each from eight Holstein Friesian breeding bulls were used as the split-sample, including two equilibration times (4 h and 24 h) and three extenders (BioXcell, Triladyl, and OptiXcell). For trial 2, from 5 to 10 ejaculates from the same bulls were collected and treated (split-sample) as BioXcell with 4 h equilibration and either Triladyl or OptiXcell, both with 24 h equilibration. A total of 11,059 straws were used for insemination of cows and heifers. For Triladyl, progressive sperm motility, acrosome defects, and plasma membrane and acrosome integrity improved with a 24 h compared to a 4 h equilibration time. Four bulls each were used with Triladyl and OptiXcell for trial 2. In trial 2, non-return rates did not differ among groups. Therefore, using a 24 h equilibration time might improve in vitro sperm parameters, depending on the extender used. Moreover, it would be possible to change from 4 h to 24 h equilibration time without impairing field fertility.

Selective Accumulation to Tumor Cells with Coacervate Droplets Formed from a Water-Insoluble Acrylate Polymer

Selective targeting of specific cells without the use of biological ligands has not been achieved. In the present study, we revealed that the coacervate droplets formed from poly(2-methoxyethyl acrylate) (PMEA) and its derivatives selectively accumulated to tumor cells. PMEA derivatives, which are insoluble acrylate polymers, induced coacervation in water to form polymer-dense droplets via hydrophobic interaction. Interestingly, the accumulation of coacervate droplets to tumor cells was involved in the bound water content of PMEA derivatives. Coacervate droplets with a high bound water content accumulated and internalized up to 36.6-fold higher in HeLa cervical tumor cells than in normal human fibroblasts (NHDF). Moreover, the interactions between coacervate droplets and plasma membrane components such as CD44 played a key role in this accumulation process. Therefore, coacervate droplets formed from PMEA derivatives have great clinical potential in tumor cell detection, development of alternative tumor-targeting ligands, and optimization of drug delivery carriers.

Sperm chromatin integrity and DNA methylation in Norwegian Red bulls of contrasting fertility

In this study, the complexity of chromatin integrity was investigated in frozen-thawed semen samples from 37 sires with contrasting fertility, expressed as 56-day non-return rates (NR56). Protamine deficiency, thiols, and disulfide bonds were assessed and compared with previously published data for DNA fragmentation index (DFI) and high DNA stainability (HDS). In addition, in vitro embryo development and sperm DNA methylation were assessed using semen samples from 16 of these bulls. The percentages of DFI and HDS were negatively associated with NR56 and cleavage rate and positively associated with sperm protamine deficiency (p < 0.05). Significant differences in cleavage and blastocyst rates were observed between bulls of high and low NR56. However, once fertilization occurred, further development into blastocysts was not associated with NR56. The differential methylation analysis showed that spermatozoa from bulls of low NR56 were hypermethylated compared to bulls of high NR56. Pathway analysis showed that genes annotated to differentially methylated cytosines could participate in different biological pathways and have important biological roles related to bull fertility. In conclusion, sperm cells from Norwegian Red bulls of inferior fertility have less compact chromatin structure, higher levels of DNA damage, and are hypermethylated compared with bulls of superior fertility.

Spermatological parameters of immunologically sexed bull semen assessed by imaging flow cytometry, and dairy farm trial

This study compared the quality parameters of bull semen sexed using an immunological method with those of conventional semen by imaging flow cytometry and applied this semen in dairy farm trials. Semen samples were collected from ten ejaculates from five bulls. Each sample was divided into two treatments: conventional semen (CON) and semen sexed using monoclonal male-specific antibodies combined with the complement system for cytotoxicity reaction (IC-sexed). After obtaining frozen-thawed semen, we used imaging flow cytometry to assess acrosome integrity, sperm sex ratio and viability. Sperm morphology was evaluated using eosin-nigrosin staining. The percentage acrosome integrity did not differ between IC-sexed and CON semen (P = 0.313). The sperm sex ratio showed that the percentage of live X-chromosome-bearing sperm was higher than that of live Y-chromosome-bearing sperm in IC-sexed semen (P = 0.001). IC-sexed semen showed a higher percentage of head and tail defects than did CON semen (P = 0.019). In field trials, 585 cows were subjected randomly to AI with CON or IC-sexed semen. The pregnancy rate of the IC-sexed group did not differ from that of the CON group (P = 0.535). However, IC-sexed semen produced a significantly higher percentage of female calves than did CON semen (P = 0.031). Thus, immunological sexing did not adversely affect the acrosome integrity of sperm. Furthermore, a female calf birth rate of over 74 % can potentially be achieved using IC-sexed semen. These findings could help farmers to replace heifers in their herds.

Sperm DNA Hypomethylation Proximal to Reproduction Pathway Genes in Maturing Elite Norwegian Red Bulls

Genomic selection in modern farming demands sufficient semen production in young bulls. Factors affecting semen quality and production capacity in young bulls are not well understood; DNA methylation, a complicated phenomenon in sperm cells, is one such factors. In this study, fresh and frozen-thawed semen samples from the same Norwegian Red (NR) bulls at both 14 and 17 months of age were examined for sperm chromatin integrity parameters, ATP content, viability, and motility. Furthermore, reduced representation bisulfite libraries constructed according to two protocols, the Ovation^® RRBS Methyl-Seq System (Ovation method) and a previously optimized gel-free method and were sequenced to study the sperm DNA methylome in frozen-thawed semen samples. Sperm quality analyses indicated that sperm concentration, total motility and progressivity in fresh semen from 17 months old NR bulls were significantly higher compared to individuals at 14 months of age. The percentage of DNA fragmented sperm cells significantly decreased in both fresh and frozen-thawed semen samples in bulls with increasing age. Libraries from the Ovation method exhibited a greater percentage of read loss and shorter read size following trimming. Downstream analyses for reads obtained from the gel-free method revealed similar global sperm DNA methylation but differentially methylated regions (DMRs) between 14- and 17 months old NR bulls. The majority of identified DMRs were hypomethylated in 14 months old bulls. Most of the identified DMRs (69%) exhibited a less than 10% methylation difference while only 1.5% of DMRs exceeded a 25% methylation difference. Pathway analysis showed that genes annotated with DMRs having low methylation differences (less than 10%) and DMRs having between 10 and 25% methylation differences, could be associated with important hormonal signaling and sperm function relevant pathways, respectively. The current research shows that RRBS in parallel with routine sperm quality analyses could be informative in reproductive capacity of young NR bulls. Although global sperm DNA methylation levels in 14 and 17 months old NR bulls were similar, regions with low and varying levels of DNA methylation differences can be identified and linked with important sperm function and hormonal pathways.

Differences in sperm functionality and intracellular metabolites in Norwegian Red bulls of contrasting fertility

In the dairy breeding industry, prediction of bull fertility in artificial insemination (AI) is important for efficient and economically sustainable production. However, it is challenging to identify bulls with superior fertility applying conventional in vitro sperm assays. In the present study, sperm functionality was investigated to identify a multivariate model that could predict fertility. Two groups of young Norwegian Red bulls were selected, one with inferior fertility (18 bulls) and one with superior fertility (19 bulls) based on non-return rate after 56 days (NR56). Frozen-thawed semen doses were analysed for sperm chromatin integrity, viability, acrosome integrity, motility, and ATP content. A targeted approach was used to study intracellular concentrations of amino acids and trace elements in viable sperm cells. Significant differences between the two groups of bulls were observed, both for sperm functional attributes and intracellular concentrations of metabolites. Pearson correlation analyses indicated a negative relationship between NR56 and chromatin integrity parameters, DNA fragmentation index (DFI) and high DNA stainability (HDS). Several motility parameters correlated positively with NR56. The concentrations of cysteine and glutamic acid in sperm cells correlated negatively with NR56, while the concentrations of aspartic acid, leucine and serine showed a positive NR56-correlation. The sperm intracellular concentrations of the trace elements Fe, Al and Zn, correlated negatively with NR56. Correlations were observed between several sperm parameters and metabolites. Stepwise multiple regression analysis indicated that the best predictor of NR56 was a model containing %DFI, together with the intracellular sperm concentration of aspartic acid, Fe and Zn. This model explained 59% of the variability in NR56.

Effect of dietary grape marc on fresh and refrigerated boar semen

In several studies there has been evaluation of the dietary addition of antioxidants to improve the quality of fresh and stored semen in domestic animals. Grape marc (GM), as the residue of vinification, contains large amounts of polyphenols with antioxidant, anti-inflammatory, antimicrobial, and antiaging effects. In this study, two regimens of dietary GM supplementation (2% and 4%) were tested regarding effects on the characteristics and lipid peroxidation of fresh and stored semen. The dietary supplementation of GM improved sperm characteristics in fresh semen, especially at 4% of GM. There were greater values for all kinetic variables and membrane integrity, and lesser values for sperm abnormalities and lipid peroxidation with 2% and 4% GM supplementation. Lipid peroxidation of the pellet was less with both 2% and 4% GM supplementation. During sperm storage, the dietary supplementation of GM improved the quality of sperm, with greater values for kinetic variables and membrane integrity at day 15 of storage. In the present study, supplementation of GM in boar diets improved fresh semen characteristics and reduced the lipid peroxidation of ejaculated spermatozoa, possibly due to the effect of polyphenols present in the GM. Consequently, this likely resulted in improved sperm quality during storage.

Sperm macrocephaly syndrome in the ostrich Struthio camelus: morphological characteristics and implications for motility

Sperm macrocephaly syndrome (SMS) is characterised by a high percentage of spermatozoa with enlarged heads and multiple tails, and is related to infertility. Although this multiple sperm defect has been described in other mammalian species, little is known about this anomaly in birds. Morphological examination of semen from nine South African black ostriches (Struthio camelus var. domesticus) involved in an AI trial revealed the variable presence of spermatozoa with large heads and multiple tails. Ultrastructural features of the defect were similar to those reported in mammals except that the multiple tails were collectively bound within the plasmalemma. The tails were of similar length and structure to those of normal spermatozoa, and the heads were 1.6-fold longer, emphasising the uniformity of the anomaly across vertebrate species. Flow cytometry identified these cells as diploid and computer-aided sperm analysis revealed that they swim slower but straighter than normal spermatozoa, probably due to the increased drag of the large head and constrained movement of the merged multiple tails. The high incidence of this defect in one male ostrich indicates that, although rare, SMS can occur in birds and may potentially have an adverse effect on breeding programs, particularly for endangered species.

Stress Resilience of Spermatozoa and Blood Mononuclear Cells without Prion Protein

The cellular prion protein PrP^C is highly expressed in neurons, but also present in non-neuronal tissues, including the testicles and spermatozoa. Most immune cells and their bone marrow precursors also express PrP^C. Clearly, this protein operates in highly diverse cellular contexts. Investigations into putative stress-protective roles for PrP^C have resulted in an array of functions, such as inhibition of apoptosis, stimulation of anti-oxidant enzymes, scavenging roles, and a role in nuclear DNA repair. We have studied stress resilience of spermatozoa and peripheral blood mononuclear cells (PBMCs) derived from non-transgenic goats that lack PrP^C (PRNP^Ter/Ter) compared with cells from normal (PRNP^+/+) goats. Spermatozoa were analyzed for freeze tolerance, DNA integrity, viability, motility, ATP levels, and acrosome intactness at rest and after acute stress, induced by Cu²⁺ ions, as well as levels of reactive oxygen species (ROS) after exposure to FeSO₄ and H₂O₂. Surprisingly, PrP^C-negative spermatozoa reacted similarly to normal spermatozoa in all read-outs. Moreover, in vitro exposure of PBMCs to Doxorubicin, H₂O₂ and methyl methanesulfonate (MMS), revealed no effect of PrP^C on cellular survival or global accumulation of DNA damage. Similar results were obtained with human neuroblastoma (SH-SY5Y) cell lines stably expressing varying levels of PrP^C. RNA sequencing of PBMCs (n = 8 of PRNP^+/+ and PRNP^Ter/Ter) showed that basal level expression of genes encoding DNA repair enzymes, ROS scavenging, and antioxidant enzymes were unaffected by the absence of PrP^C. Data presented here questions the in vitro cytoprotective roles previously attributed to PrP^C, although not excluding such functions in other cell types or tissues during inflammatory stress.

Comparison of phagocytosis in three Caribbean Sea urchins

In 1983 large numbers of the sea urchin Diadema antillarum unexplainably began showing signs of illness and dying in the Caribbean, and over the next year they came close to extinction, making it one of the worst mass mortality events on record. Present evidence suggests a water-borne pathogen as the etiological agent. Decades later Diadema densities remain low, and its near extinction has been a major factor in transforming living coral reefs in the Caribbean to barren algae-covered rock. In the ensuing decades, no solid explanation has been found to the questions: what killed Diadema; why did Diadema succumb while other species of urchins on the same reefs did not; and why has Diadema still not recovered? A recent hypothesis posited by our lab as to Diadema's vulnerability was directed at possible compromised immunity in Diadema, and experimental results found a significantly impaired humoral response to a key component of gram-negative bacteria. Here we use flow cytometry to examine the cellular arm of invertebrate immunity. We performed cytotoxicity and phagocytosis assays as a measure of the cellular immune responses of cells from Diadema and two other species of sea urchins not affected by the die-off. Despite our previous findings of in impaired humoral response, our study found no apparent difference in the cellular phagocytic response of Diadema compared to the other urchin species studied.

RNA sequencing reveals candidate genes and polymorphisms related to sperm DNA integrity in testis tissue from boars

Background

Sperm DNA is protected against fragmentation by a high degree of chromatin packaging. It has been demonstrated that proper chromatin packaging is important for boar fertility outcome. However, little is known about the molecular mechanisms underlying differences in sperm DNA fragmentation. Knowledge of sequence variation influencing this sperm parameter could be beneficial in selecting the best artificial insemination (AI) boars for commercial production. The aim of this study was to identify genes differentially expressed in testis tissue of Norwegian Landrace and Duroc boars, with high and low sperm DNA fragmentation index (DFI), using transcriptome sequencing.

Results

Altogether, 308 and 374 genes were found to display significant differences in expression level between high and low DFI in Landrace and Duroc boars, respectively. Of these genes, 71 were differentially expressed in both breeds. Gene ontology analysis revealed that significant terms in common for the two breeds included extracellular matrix, extracellular region and calcium ion binding. Moreover, different metabolic processes were enriched in Landrace and Duroc, whereas immune response terms were common in Landrace only. Variant detection identified putative polymorphisms in some of the differentially expressed genes. Validation showed that predicted high impact variants in RAMP2, GIMAP6 and three uncharacterized genes are particularly interesting for sperm DNA fragmentation in boars.

Conclusions

We identified differentially expressed genes between groups of boars with high and low sperm DFI, and functional annotation of these genes point towards important biochemical pathways. Moreover, variant detection identified putative polymorphisms in the differentially expressed genes. Our results provide valuable insights into the molecular network underlying DFI in pigs.

Electronic supplementary material

The online version of this article (10.1186/s12917-017-1279-x) contains supplementary material, which is available to authorized users.

Fusion of Boar Sperm with Nanoliposomes Prepared from Synthetic Phospholipids

Liposomes are artificial membrane vesicles that can be used to test and model the functions and interactions of various biological membranes, or as a carrier system to deliver biologically active substances into the cells, or to incorporate lipids into the plasma membrane of target cells to modify membrane structure-function relationships. Sperm plasma membrane undergoes lipid modification during maturation in epididymis and during capacitation in the female reproductive tract to facilitate fertilization. Natural variation in the amounts and composition of lipids in the sperm plasma membrane may also contribute to the species-specific sperm sensitivities to handling and storage conditions. Boar sperm are notoriously susceptible to membrane damage and are resistant to compositional alteration by artificial liposomes. This study used flow cytometry to demonstrate stable incorporation of nanoliposomes prepared from a complex mixture of various phospholipids (phosphatidylcholine : phosphatidylethanolamine : sphingomyelin : phosphatidylserine : phosphatidylinositol) with high fusion efficiency. Over 90% of sperm rapidly took up fluorescently labelled liposomes and retained the lipids for at least 60 min, in a significant time- and concentration-dependent manner. This unique fusion efficacy could be used to alter sperm plasma membrane composition and hence membrane-based functional responses.

X-ray and ultraviolet C irradiation-induced γ-H2AX and p53 formation in normal human periosteal cells in vitro: markers for quality control in cell therapy

BACKGROUND AIMS

For successful cell transplantation therapy, the quality of cells must be strictly controlled. Unfortunately, to exclude inappropriate cells that possess structurally abnormal chromosomes, currently only karyotyping functions as an assessment. Unfortunately, this methodology is time-consuming and only effective for metaphasic cells. To develop a more efficient, inclusive and sensitive methodology, we examined the phosphorylation of histone H2AX and the p53 levels in normal human periosteal cells exposed to x-rays or other oxidative stressors.

METHODS

Periosteal cells were obtained from human alveolar bone before being exposed to x-rays, ultraviolet C or hydrogen peroxide. The cell cycle, electric nuclear volume and CD44 expression were evaluated using flow cytometry, and the phosphorylated H2AX (γ-H2AX), p53, p21 and proliferating cell nuclear antigen (PCNA) levels were evaluated by Western blot analyses.

RESULTS

Each oxidative stress dose-dependently arrested cell growth and partially induced premature cellular senescence. In parallel, each oxidative stress rapidly phosphorylated H2AX and stabilized p53, and intense stress sustained these high levels for at least 8 days.

CONCLUSIONS

Intensive oxidative stress induces sustained high levels of γ-H2AX and p53, which force cells toward senescence or non-apoptotic cell death. Lower doses of oxidative stress induced more modest and transient increases in γ-H2AX and p53, and these cells eventually survive. However, because DNA is repaired without a template in the majority of these cells, G1 mutations accumulate. Therefore, we recommend that any cell population expressing elevated γ-H2AX and p53 levels be excluded from cell transplantation therapy.