TLR7/8 signalling affects X-sperm motility via the GSK3 α/β-hexokinase pathway for the efficient production of sexed dairy goat embryos

Expression of TLR7/8 in canine sperm and evaluation of the effect of ligand R848 on the sorting of canine X/Y sperm

The aim of this study was to analyze the expression pattern of Toll receptor 7/8 (TLR7/8) in canine sperm, and explore the feasibility of using TLR7/8 ligand resiquimod(R848)to separate canine X and Y sperm. In this study, cellular immunofluorescence was used to analyze the expression of TLR7/8 in canine sperm, real-time fluorescence quantitative PCR was used to calculate the proportion of X sperm in the lower layer of the incubation solution with R848 to evaluate the sorting effect of R848 on canine X/Y sperm, and sperm quality detection system was used to analyze the effect of R848 on the motility of canine sperm. The mechanism of effect of R848 on canine sperm motility was analyzed by Western blot. The results showed that TLR8 was not expressed in all canine sperm, while TLR7 was expressed in all canine sperm and was localized in the head and tail of sperm. When 0.4 μM R848 was incubated with canine sperm for 1 h, the total motility, average path velocity (VAP), average straight-line velocity (VSL), and average curved-line velocity (VCL) of canine sperm were significantly decreased(P < 0.05). There was no significant difference between the lower and upper layers of the R848 treatment group and the control group(P > 0.05), and the proportion of X sperm was nearly half. The levels of NF-κB and GSK3α/β phosphorylation of sperm in R848 treatment group were significantly increased compared with control group(P < 0.05). The above results showed that TLR7/8 was not differentially expressed in canine X and Y sperm. R848 could decrease the motility of canine spermatozoa and inhibit sperm motility by the GSK3α/β-hexokinase pathway through the phosphorylation of NFκB and GSK3α/β, while could not separate X and Y spermatozoa. The method of sorting X/Y sperm based on TLR7/8 is not feasible for dogs.

In vitro characteristics of X- and Y-bearing ram spermatozoa sorted by bovine serum albumin (BSA) column and TLR7/8 ligand R848

The quality of the separated fractions in sex-sorted semen is very important for the success of the artificial insemination. This study aimed to evaluate some in vitro characteristics (DNA quantity, kinematic parameters and enzymes activity) of X- and Y-bearing ram spermatozoa sorted by bovine serum albumin (BSA) column and toll-like receptors (TLR)7/8 ligand R848. The ejaculates from six rams were collected by artificial vagina and subjected to a computer-assisted semen analysis (CASA). Total motility and percentage of the sperms with rapid and medium progressivity or non-progressivity in whole ejaculates and in X and Y fractions were analyzed. Activity of the enzymes ALP, GGT, CK, LDH and accumulation of lactate in the seminal plasma of ejaculates and in the environmental fluid of sexed spermatozoa were measured by biochemical analyzer. DNA was isolated from precipitated spermatozoa, and its quantity was measured. For both protocols the DNA mass from X-bearing fractions was higher, than from Y-bearing fractions. The high total motility of X- and Y-bearing spermatozoa as well as greater percent sperms with progressive motility were observed after use of BSA protocol. The application of TLR7/8 ligand R848 protocol led to reducing of Y-sperm motility and enhancement of non-progressivity in both fractions, which corresponded to the determined high amount of the extracellular lactate. For both methods, the significantly reduced activity of enzymes in the X and Y spermatozoa environmental fluids was established. Both protocols produce X- and Y-sperm fractions with satisfactory quality (over 80% total motility and over 50% rapid and medium progressive spermatozoa in each fraction).

Gender Control of Mouse Embryos by Activation of TLR7/8 on X Sperm via Ligands dsRNA-40 and dsRNA-DR

Gender control technologies are promising for enhancing the production efficiency of the farm animal industry, and preventing sex-linked hereditary diseases in humans. It has been shown that the X sperm of mammalian animals specifically expresses X-chromosome-derived toll-like receptor 7/8 (TLR7/8), and the activation of TLR7/8 on the X sperm by their agonist, R848, can separate X and Y sperm via the specific inhibition of X sperm motility. The use of R848-preselected sperm for fertilization resulted in sex-ratio-skewed embryos or offspring. In this study, we aimed to investigate whether two other TLR7/8 ligands, double-stranded RNA-40 (dsRNA-40) and double-stranded RNA-DR (dsRNA-DR), are also effective in the separation of mouse X and Y sperm and the subsequent generation of gender-ratio-skewed in vitro fertilization (IVF) embryos. Our results indicated that cholesterol modification significantly enhances the transfection of dsRNA-40 and dsRNA-DR into sperm cells. dsRNA-40 and dsRNA-DR incubation with mouse sperm could separate X and Y sperm by the specific suppression of X sperm motility by decreasing its ATP level and mitochondrial activity. The use of a dsRNA-40- or dsRNA-DR-preselected upper layer of sperm, which predominantly contains high-motility Y sperm, for IVF caused a male-biased sex ratio shift in resulting embryos (with 65.90-74.93% of embryos being male). This study develops a simple new method for the efficient separation of mammalian X and Y sperm, enabling the selective production of male or female progenies.

Standardization of a Sex-Sorting Protocol for Stallion Spermatozoa by Means of Absolute RT-qPCR

Sperm sexing is a technology that can generate great economic benefits in the animal production sector. Techniques such as sex-sorting promise over 90% accuracy in sperm sexing. However, for the correct standardization of the technique, some laboratory methodologies are required. The present manuscript describes in detail a standardized equine sperm sex-sorting protocol using an absolute qPCR-based methodology. Furthermore, the results of absolute qPCR were implemented and validated by generating equine/bovine heterologous embryos by intracytoplasmic sperm injection (ICSI) of presumably sexed equine spermatozoa into bovine oocytes using a piezoelectric system (Piezo-ICSI). Our results indicated that equine sex-sorting spermatozoa had a 97% and 94% certainty for X and Y sperm, respectively, while presumptive female and male equine/bovine hybrid embryos, generated by Piezo-ICSI, had an accuracy of 92% with respect to the desired sex. Therefore, it is concluded that the presented methodology is a reliable, cost-effective, and relatively simple option for standardizing sex-sorting of equine spermatozoa. This is supported by the results of the correct sexing of Piezo-ICSI heterologous embryos generated with the sexed spermatozoa, validating the correct sexing and viability of these gametes.

Biochemical Features of X or Y Chromosome-Bearing Spermatozoa for Sperm Sexing

This review presents information on biochemical features of spermatozoa bearing X or Y chromosome, enabling production of a sperm fraction with pre-defined sex chromosome. The almost only technology currently used for such separation (called sexing) is based on the fluorescence-activated cell sorting of sperm depending on DNA content. In addition to the applied aspects, this technology made it possible to analyze properties of the isolated populations of spermatozoa bearing X or Y chromosome. In recent years, existence of the differences between these populations at the transcriptome and proteome level have been reported in a number of studies. It is noteworthy that these differences are primarily related to the energy metabolism and flagellar structural proteins. New methods of sperm enrichment with X or Y chromosome cells are based on the differences in motility between the spermatozoa with different sex chromosomes. Sperm sexing is a part of the widespread protocol of artificial insemination of cows with cryopreserved semen, it allows to increase proportion of the offspring with the required sex. In addition, advances in the separation of X and Y spermatozoa may allow this approach to be applied in clinical practice to avoid sex-linked diseases.

Diluent pH affects sperm motility via GSK3 α/β-hexokinase pathway for the efficient enrichment of X-sperm to increase the female kids rate of dairy goats

Dairy goats are the goats bred with the ability to produce large quantities of milk, and the increase of the female kid rate of breeding dairy goats is beneficial for milk production and economic benefits of dairy goat farms. Our previous study revealed that regulating the pH of dairy goat semen diluent to 6.2 or 7.4 respectively, the proportion of X chromosome bearing sperm (X-sperm) in the up and down layers of the tube after incubation was significantly higher than that of Y chromosome bearing sperm (Y-sperm) i.e. enriched X-sperm. In this study, fresh dairy goat semen collected in different seasons was diluted in different pH solutions to calculate the number and rate of X-sperm and to measure the functional parameters of enriched sperm. The artificial insemination experiments were performed with enriched X-sperm. The mechanisms of regulating the pH of diluent affecting sperm enrichment were further studied. The results showed that the proportion of enriched X-sperm in pH 6.2 and 7.4 diluents of sperm collected in different seasons showed no significantly different, but were significantly higher than that of the control group (pH 6.8). The in vitro functional parameters of X-sperm enriched in pH 6.2 and 7.4 diluent solution were not significantly different from those of the control group (P > 0.05). After artificial insemination with X-sperm enriched in pH7.4 diluent, the proportion of female offspring was significantly higher than that of the control group. It was found that the regulating pH of the diluent affected sperm mitochondrial activity and glucose uptake capacity via phosphorylating NF-κB and GSK3α/β proteins. The motility activity of X-sperm was enhanced under acidic conditions and weakened under alkaline conditions, which was conducive to the effective enrichment of X-sperm. This study demonstrated that the number and proportion of X-sperm enriched using pH 7.4 diluent were elevated, and the proportion of female kids was increased. This technology can be used for the reproduction and production of dairy goats in farms at large scales.

Single-cell transcriptomics reveals male germ cells and Sertoli cells developmental patterns in dairy goats

Spermatogenesis holds considerable promise for human-assisted reproduction and livestock breeding based on stem cells. It occurs in seminiferous tubules within the testis, which mainly comprise male germ cells and Sertoli cells. While the developmental progression of male germ cells and Sertoli cells has been widely reported in mice, much less is known in other large animal species, including dairy goats. In this study, we present the data of single cell RNA sequencing (scRNA-seq) for 25,373 cells from 45 (pre-puberty), 90 (puberty), and 180-day-old (post-puberty) dairy goat testes. We aimed to identify genes that are associated with key developmental events in male germ cells and Sertoli cells. We examined the development of spermatogenic cells and seminiferous tubules from 15, 30, 45, 60, 75, 90, 180, and 240-day-old buck goat testes. scRNA-seq clustering analysis of testicular cells from pre-puberty, puberty, and post-puberty goat testes revealed several cell types, including cell populations with characteristics of spermatogonia, early spermatocytes, spermatocytes, spermatids, Sertoli cells, Leydig cells, macrophages, and endothelial cells. We mapped the timeline for male germ cells development from spermatogonia to spermatids and identified gene signatures that define spermatogenic cell populations, such as AMH, SOHLH1, INHA, and ACTA2. Importantly, using immunofluorescence staining for different marker proteins (UCHL1, C-KIT, VASA, SOX9, AMH, and PCNA), we explored the proliferative activity and development of male germ cells and Sertoli cells. Moreover, we identified the expression patterns of potential key genes associated with the niche-related key pathways in male germ cells of dairy goats, including testosterone, retinoic acid, PDGF, FGF, and WNT pathways. In summary, our study systematically investigated the elaborate male germ cells and Sertoli cells developmental patterns in dairy goats that have so far remained largely unknown. This information represents a valuable resource for the establishment of goat male reproductive stem cells lines, induction of germ cell differentiation in vitro, and the exploration of sequential cell fate transition for spermatogenesis and testicular development at single-cell resolution.

High-Efficiency Bovine Sperm Sexing Used Magnetic-Activated Cell Sorting by Coupling scFv Antibodies Specific to Y-Chromosome-Bearing Sperm on Magnetic Microbeads

Sperm sexing technique is favored in the dairy industry. This research focuses on the efficiency of bovine sperm sexing using magnetic-activated cell sorting (MACS) by scFv antibody against Y-chromosome-bearing sperm (Y-scFv) coupled to magnetic microbeads and its effects on kinematic variables, sperm quality, and X/Y-sperm ratio. In this study, the optimal concentration of Y-scFv antibody coupling to the surface of magnetic microbeads was 2–4 mg/mL. PY-microbeads revealed significantly enriched Y-chromosome-bearing sperm (Y-sperm) in the eluted fraction (78.01–81.43%) and X-chromosome-bearing sperm (X-sperm) in the supernatant fraction (79.04–82.65%). The quality of frozen–thawed sexed sperm was analyzed by CASA and imaging flow cytometer, which showed that PY-microbeads did not have a negative effect on X-sperm motility, viability, or acrosome integrity. However, sexed Y-sperm had significantly decreased motility and viability. The X/Y-sperm ratio was determined using an imaging flow cytometer and real-time PCR. PY-microbeads produced sperm with up to 82.65% X-sperm in the X-enriched fraction and up to 81.43% Y-sperm in the Y-enriched fraction. Bovine sperm sexing by PY-microbeads showed high efficiency in separating Y-sperm from X-sperm and acceptable sperm quality. This initial technique is feasible for bovine sperm sexing, which increases the number of heifers in dairy herds while lowering production expenses.

Cell-Specific Expression Pattern of Toll-Like Receptors and Their Roles in Animal Reproduction

Toll-like receptors (TLRs), a part of the innate immune system, have critical roles in protection against infections and involve in basic pathology and physiology. Secreted molecules from the body or pathogens could be a ligand for induction of the TLR system. There are many immune and non-immune types of cells that express at a least single TLR on their surface or cytoplasm. Those cells may be a player in a defense system or in the physiological regulation mechanisms. Reproductive tract and organs contain different types of cells that have essential functions such as hormone production, providing an environment for embryo/fetus, germ cell production, etc. Although lower parts of reproductive organs are in a relationship with outsider contaminants (bacteria, viruses, etc.), upper parts should be sterile to provide a healthy pregnancy and germ cell production. In those areas, TLRs bear controller or regulator roles. In this chapter, we will provide current information about physiological functions of TLR in the cells of the reproductive organs and tract, and especially about their roles in follicle selection, maturation, follicular atresia, ovulation, corpus luteum (CL) formation and regression, establishment and maintenance of pregnancy, sperm production, maturation, capacitation as well as the relationship between TLR polymorphism and reproduction in domestic animals. We will also discuss pathogen-associated molecular patterns (PAMPs)-induced TLRs that involve in reproductive inflammation/pathology.