Spermatozoa input concentrations and RNA isolation methods on RNA yield and quality in bull (Bos taurus)

Development and optimization of an efficient RNA isolation protocol from bovine (Bos indicus) spermatozoa

Achieving the optimum extraction of RNA from spermatozoal cells is crucial for carrying out effective high-throughput analysis regarding its role in fertility and other reproduction processes in Bos indicus. Nevertheless, semen comprises spermatozoa and several other secretions from the male reproductive system, which as well consist of diverse somatic cell types. Therefore, the elimination of somatic cells guarantees the purity of the sperm RNA. In the present study, we tested five different RNA isolation protocols and evaluated them for their yield and purity using spectrophotometer and polymerase chain reaction. Among the five RNA isolation protocols, the Triazol + RNAeasy plus Kit + TCEP method revealed optimum performance. We successfully achieved isolation of spermatozoal RNA without any spermatozoal DNA contamination from Bos indicus spermatozoa that contains approx. 1000 to 10,000 times less RNA as compared to other mammalian somatic cells. RNA quality was assessed using primers Protamine1 (spermatozoal RNA and spermatozoal DNA), CDH1 (epithelial cell), KIT (germ cell) and PTPRC (leukocytes) designed using primer BLAST where there was no product amplified except Prm1 whose product size was specific for spermatozoal RNA. The results of our investigation on RNA isolation procedures indicate that the inclusion of a disulphide reducing agent (TCEP) is crucial for the process of sperm cell lysis.

Effect of naringenin on post-thaw quality, fertility-associated gene expression and fertilization potential of buffalo (Bubalus bubalis) bull sperm

Our objectives were to explore the effect of naringenin addition in the semen extender on the post-thaw 1) sperm quality, 2) fertility-associated gene expression, and 3) fertilization potential of buffalo bull sperm. In experiment 1, semen samples (n = 32) from four Nili-Ravi buffalo bulls were pooled (n = 8) and diluted with the tris-citric acid (TCF-EY) extender containing different concentrations of naringenin, i.e., placebo (DMSO), 0 (control), 50, 100, 150 and 200 μM naringenin. After dilution, semen samples were packed in 0.5 mL French straws, cryopreserved and analyzed for post-thawed sperm quality and gene expression. Computer-assisted Semen Analysis, Hypo-osmotic Swelling test, Normal Apical Ridge assay, Rhodamine 123, Acridine orange, Propidium iodide staining and Thiobarbituric Acid Reactive Substances assay were performed to assess sperm motility parameters, plasma membrane functionality, acrosome integrity, mitochondrial membrane potential, DNA integrity, viability and lipid peroxidation, respectively. Expression levels of sperm acrosome-associated SPACA3, DNA condensation-related PRM1, anti-apoptotic BCL2, pro-apoptotic BAX, and oxidative stress-associated ROMO1 genes were evaluated through qPCR. Results revealed that total and progressive motility, plasma membrane functionality, acrosome integrity, mitochondrial membrane potential, DNA integrity and viability were higher (P < 0.05) with 50, 100 and 150 μM naringenin compared to 200 μM naringenin, placebo and control groups. Moreover, all naringenin-treated groups improved catalase activity, and reduced lipid peroxidation compared to placebo and control groups (P < 0.05). Relative expression levels of SPACA3 and PRM1 genes were higher (P < 0.05) with 150 μM naringenin compared to all groups except 100 μM (P > 0.05). No difference (P > 0.05) in the expression level of BCL2 gene was observed among all groups. Furthermore, BAX gene was expressed higher (P < 0.05) in the 200 μM naringenin group, whereas no difference (P > 0.05) in expression was noticed among the remaining groups. In addition, ROMO1 gene was expressed lower (P < 0.05) in all naringenin-treated groups compared to the control. In experiment 2, the in vivo fertility of semen doses (n = 400; 200/group) containing optimum concentration of naringenin (150 μM; depicted better in vitro sperm quality in experiment 1) was compared with control during the breeding season. Buffaloes were inseminated 24 h after the onset of natural estrus and palpated transrectal for pregnancy at least 60 days post-insemination. The fertility rate of 150 μM naringenin group was higher (P = 0.0366) compared to the control [57.00 ± 0.03 % (114/200) vs. 46.50 ± 0.04 % (93/200), respectively]. Taken together, it is concluded that naringenin supplementation in semen extender improves post-thaw quality, fertility-associated gene expression and fertilization potential of buffalo bull sperm, more apparently at 150 μM concentration.

Optimized total RNA isolation from bovine sperm with enhanced sperm head lysis

Increasing evidence of sperm RNA's role in fertilization and embryonic development has provided impetus for its isolation and thorough characterization. Sperm are considered tough-to-lyse cells due to the compact condensed DNA in sperm heads. Lack of consensus among bovine sperm RNA isolation protocols introduces experimental variability in transcriptome studies. Here, we describe an optimized method for total RNA isolation from bovine sperm using the TRIzol reagent. This study critically investigated the effects of various lysis conditions on sperm RNA isolation. Sperm suspended in TRIzol were subjected to a combination of mechanical treatments (sonication and passage through a 30G needle and syringe) and chemical treatments (supplementation with reducing agents 1,4-dithiothreitol and tris(2-carboxyethyl) phosphine hydrochloride (TCEP)). Microscopic evaluation of sperm lysis confirmed preferential sperm tail versus sperm head lysis. Interestingly, only TCEP-supplemented TRIzol (both mechanical treatments) had progressive sperm head lysis and consistently yielded total sperm RNA. Furthermore, RNA integrity was confirmed based on the electrophoresis profile and an absence of genomic DNA and somatic cells (e.g., epithelial cells, spermatids, etc.) with RT-qPCR. Our findings highlighted the importance of sperm lysis, specifically of the sperm head using TCEP with mechanical treatment, in total RNA isolation and presented a bovine-specific sperm RNA isolation method to reduce experimental variabilities.

Expression of PLCZ1 mRNA in spermatozoa of Criollo and European bulls in a low-input system

Sperm motility and kinematics analysis are important to predict bull fertility. However, there are other molecules in the sperm with the ability to improve the pregnancy rate. For example, PLCZ1 is a sperm protein that plays a unique role in the activation of the zygote and is important for the survival of the embryo. The objective of this work was to compare the expression of PLCZ1 mRNA in sperm cells of Chihuahuan Criollo and European bulls in the winter and summer seasons, under a low-input system. Six (3.33 ± 0.43 years old) bulls (three Criollo, three European) were used. Gross and individual motility were measured in semen obtained by electrostimulation. The cell pack was pelletized by centrifugation and stored in liquid nitrogen. The sperm cells were purified and total RNA was extracted. cDNA was synthesized to perform qPCR and measure the relative level of PLCZ1 transcripts in each bull. There were no differences in individual motility, however, gross motility was lower (P < 0.05) in Criollo bulls, both in the winter (71.1 ± 2.8 vs. 76.6 ± 2.8%) and in the summer season (58.9 ± 2.8 vs. 77.7 ± 2.8%). PLCZ1 expression was 5.3 times higher (P < 0.05) in winter than in summer (5.09 ± 1.09 vs 0.959 ± 1.09). No difference (P>0.05) was found in the expression levels of PLCZ1 between both breeds (4.36 ± 1.09 vs 1.69 ± 1.09), for Criollo and European, respectively. Although the animals presented seminal motility within the recommended limits for insemination, the expression levels of PLCZ1 vary depending on the time of the year and this might impact the rate of successful pregnancies. Therefore, it is important to complement conventional analysis of seminal quality with molecular characteristics.

Ameliorative effect of crocin on post-thaw quality, fertility-associated gene expression and fertilization potential of buffalo (Bubalus bubalis) bull sperm

Buffalo bull sperm suffer more cryoinjuries due to lipid peroxidation of high structural polyunsaturated fatty acid contents than cattle sperm. Consequently, the post-thaw fertilization potential of buffalo bull sperm is compromised. Crocin is a carotenoid known for its antioxidant potential through scavenging reactive oxygen species. Objectives of the current study were to investigate the effect of crocin addition in the semen extender on post-thaw quality, fertility-associated gene expression and fertilization potential of buffalo bull sperm. Semen samples (n = 32) from four Nili-Ravi buffalo bulls were extended with tris-citric acid extender containing different concentrations of crocin (0 mM; control, 0.5, 1, 1.5 and 2 mM). The extended semen was packed in 0.5 mL French straws (25 × 106 sperm/straw) and cryopreserved in liquid nitrogen. Computer-assisted semen analysis, hypo-osmotic swelling test, normal apical ridge assay, Rhodamine 123, acridine orange, propidium iodide staining, and thiobarbituric acid reactive substances assay were performed to assess sperm motility parameters, plasma membrane integrity, acrosome integrity, mitochondrial membrane potential, DNA integrity, viability, and lipid peroxidation, respectively. Expression levels of sperm acrosome-associated SPACA3, DNA condensation-related PRM1, anti-apoptotic BCL2, pro-apoptotic BAX, and oxidative stress-associated ROMO1 genes were evaluated through qPCR. The fertility of semen doses containing the most potent concentration of crocin (based on optimum post-thaw semen quality) was compared with control during the breeding season. Buffaloes (n = 400; 200/group) were inseminated 24 h after the onset of oestrus and transrectally palpated for pregnancy at least 60 days post-insemination. Results revealed that 0.5 and 1 mM crocin improved sperm post-thaw total motility, plasma membrane integrity, acrosome integrity, mitochondrial membrane potential and viability, and 1 and 1.5 mM crocin enhanced catalase activity and reduced lipid peroxidation compared to control (p < .05). Moreover, 1 mM crocin improved sperm post-thaw progressive motility, kinematics, and DNA integrity, and 1.5 mM crocin enhanced plasma membrane integrity than control (p < .05). Expression levels of SPACA3, PRM1 and BCL2 genes were higher (p < .05) with 1 mM crocin compared to other groups. In contrast, no difference (p > .05) was noticed in expressions of BAX and ROMO1 genes among all groups. The fertility rate of semen doses containing the most potent concentration (1 mM) of crocin was higher (p = .0465) compared to control (56 ± 0.03% vs. 46 ± 0.04%, respectively). In conclusion, 1 mM crocin in the semen extender improves post-thaw quality, fertility-associated gene expression and fertilization potential of buffalo bull sperm.

Identification of hub genes and their expression profiling for predicting buffalo (Bubalus bubalis) semen quality and fertility

Sperm transcriptomics provide insights into subtle differences in sperm fertilization competence. For predicting the success of complex traits like male fertility, identification of hub genes involved in various sperm functions are essential. The bulls from the transcriptome profiled samples (n = 21), were grouped into good and poor progressive motility (PM), acrosome integrity (AI), functional membrane integrity (FMI) and fertility rate (FR) groups. The up-regulated genes identified in each group were 87, 470, 1715 and 36, respectively. Gene networks were constructed using up- and down-regulated genes from each group. The top clusters from the upregulated gene networks of the PM, AI, FMI and FR groups were involved in tyrosine kinase (FDR = 1.61E-11), apoptosis (FDR = 1.65E-8), translation (FDR = 2.2E-16) and ribosomal pathway (FDR = 1.98E-21), respectively. From the clusters, the hub genes were identified and validated in a fresh set of semen samples (n = 12) using RT-qPCR. Importantly, the genes (fold change) RPL36AL (14.99) in AI, EIF5A (54.32) in FMI, and RPLP0 (8.55) and RPS28 (13.42) in FR were significantly (p < 0.05) up-regulated. The study suggests that the expression levels of MAPK3 (PM), RPL36AL + RPS27A or RPL36AL + EXT2 (AI), RPL36AL or RPS27A (FMI) and RPS18 + RPS28 (FR) are potential markers for diagnosing the semen quality and fertility status of bulls which can be used for the breeding program.

Comparative RNA isolation methods from fresh ejaculated spermatozoa in Sahiwal cattle (Bos indicus) and Murrah buffalo (Bubalus bubalis) bulls for high quality and enhanced RNA yield

Sperm mRNA transcriptional profiling can be used to evaluate the fertility of breeding bulls. The aim of the study was to compare the modified RNA isolation methods for higher RNA yield and quality from freshly ejaculated sperm of cattle and buffalo bulls. Ten fresh ejaculates from each Sahiwal (n = 10 bulls × 10 ejaculates) and Murrah bulls (n = 10 bulls x 10 ejaculates) were used for RNA isolation. From the recovered live sperm, total sperm RNA was isolated by conventional methods (TRIzol, Double TRIzol), membrane-based methods combined with TRIzol (RNeasy + TRIzol) with the addition of β-mercaptoethanol (BME) and Kit (RNeasy mini) methods in fresh semen. Among different isolation methods; the membrane-based modified methods combined with TRIzol (RNeasy + TRIzol) with the addition of β-mercaptoethanol (BME) resulted significantly (p < .05) higher total RNA quantity (300-340 ng/µL) and better purity in different concentrations of spermatozoa viz., 30-40 million, 70-80 million and 300-400 million sperm. The study concluded that the inclusion of BME to the combined membrane-based methods with somatic cell lysis buffer solution was best for constant increased yield and purity of RNA isolation from Sahiwal cattle and Murrah buffalo bull sperm.

Effect of cryopreservation and capacitation on expression patterns of ATP synthesis associated genes in bubaline spermatozoa

This study investigated the expression patterns of certain ATP synthesis associated genes (GAPDHS, PGK2, ENO4 and MDH2) in fresh and frozen-thawed bubaline spermatozoa vis-à-vis capacitation. Eight adult Murrah buffalo bulls, aged 5-7 years, were randomly selected from a bull farm and fresh semen was collected once a week for four weeks (n = 32) from the selected bulls. Simultaneously, frozen straws of the same bulls were collected (n = 32, four straws were pooled per sample). The samples were divided into four groups i.e., fresh non capacitated (control/group 1), fresh capacitated (group 2), frozen non capacitated (group 3) and frozen capacitated (group 4). In all groups mRNA extraction was done. The mRNA expression of GAPDHS was significantly higher in group 3 compared to the other groups, whereas the expression of ENO4 was significantly up-regulated in group 2 and 3 compared to the group 4. Similarly, the mRNA expression of PGK2 was significantly up-regulated in group 3 whereas in case of MDH2, it was significantly higher in group 2, 3 and 4 compared group 1. It can be concluded from our study that freezing and capacitation has a significant effect on the expression dynamics of the ATP synthesis-associated genes warranting necessary interventions in handling procedures to minimise the adverse effect of freezing on ATP synthesis process to ensure persistence of fertilizing ability of sperm.

Development and validation of most efficient RNA isolation method from buffalo bull spermatozoa

BACKGROUND

Being highly fragmented and low in concentration, isolation of good quality RNA from sperm cells is a big challenge. Attempts have been made to evaluate various sperm RNA isolation methods from purified buffalo bull sperm cells.

METHODS

Both, non-membrane and membrane-based methods have been evaluated for isolating RNA from Murrah buffalo sperms and compared for their respective efficacies. The traditional TRIzol, TRIzol-heat lysed (H-TRIzol) and cocktail of TCEP-RLT lysis buffer (Qiagen RNeasy mini kit)-TRIzol (C-TRIzol) based isopropanol isolation methods have been evaluated.

RESULTS

H-TRIzol yielded best results among conventional methods. The combined T-RLT RNA isolation protocol yielded best quality and quantity compared to other membrane-based methods, due to high lytic property of cocktail of lysis reagents, necessary for complete breakdown of sperm membrane and RNA binding membrane for RNA isolation. Combined lysis performed by treatment with RLT-T and T-RLT differing in order of reagents used were also evaluated. T-RLT combination giving better results compared to RLT-T due to high gDNA contamination and membrane clogging in later protocol steps.

CONCLUSION

Overall, in terms of total RNA quantity and quality per million spermatozoa, the heat-lysed TRIzol method (H-TRIzol) performs best among RNA separation techniques employed and is also quite easy to perform. This comparative evaluation of sperm RNA isolation protocols can be useful in deciding the best protocol for isolation of good quality and high concentration sperm RNA from buffalo semen, for transcriptome and other downstream studies.

Cryostress induces fragmentation and alters the abundance of sperm transcripts associated with fertilizing competence and reproductive processes in buffalo

The study aimed to assess the influence of cryostress on RNA integrity and functional significance in sperm fertilizing ability. The fresh and post-thawed buffalo sperm (n = 6 each) samples were evaluated for their functional attributes, and sperm total RNA was subjected to transcriptome sequencing followed by validation using real-time PCR and dot blot. Overall, 6911 genes had an expression of FPKM > 1, and among these 431 genes were abundantly expressed (FPKM > 20) in buffalo sperm. These abundantly expressed genes regulate reproductive functions such as sperm motility (TEKT2, SPEM1, and PRM3, FDR = 1.10E-08), fertilization (EQTN, PLCZ1, and SPESP1, FDR = 7.25E-06) and the developmental process involved in reproduction (SPACA1, TNP1, and YBX2, FDR = 7.21E-06). Cryopreservation significantly (p < 0.05) affected the structural and functional membrane integrities of sperm. The expression levels of transcripts that regulate the metabolic activities and fertility-related functions were compromised during cryopreservation. Interestingly, cryostress induces the expression of genes involved (p < 0.05) in chemokine signaling (CX3CL1, CCL20, and CXCR4), G-protein coupled receptor binding (ADRB1, EDN1, and BRS3), translation (RPS28, MRPL28, and RPL18A), oxidative phosphorylation (ND1, ND2, and COX2), response to reactive oxygen species (GLRX2, HYAL2, and EDN1), and immune responses (CX3CL1, CCL26, and TBXA2R). These precociously expressed genes during cryopreservation alter the signaling mechanisms that govern sperm functional competence and can impact fertilization and early embryonic development.

Sperm Transcriptome Analysis Accurately Reveals Male Fertility Potential in Livestock

Nowadays, selection of superior male candidates in livestock as a source of frozen semen based on sperm quality at the cellular level is not considered accurate enough for predicting the potential of male fertility. Sperm transcriptome analysis approaches, such as messenger RNA levels, have been shown to correlate with fertility rates. Using this technology in livestock growth has become the principal method, which can be widely applied to predict male fertility potential in the livestock industry through the analysis of the sperm transcriptome. It provides the gene expression to validate the function of sperm in spermatogenesis, fertilization, and embryo development, as the parameters of male fertility. This review proposes a transcriptomic analysis approach as a high-throughput method to predict the fertility potential of livestock more accurately in the future.

Cryopreservation process alters the expression of genes involved in pathways associated with the fertility of bull spermatozoa

In bovines, cryopreserved semen is used for artificial insemination; however, the fertility of cryopreserved semen is far lower than that of fresh semen. Although cryopreservation alters sperm phenotypic characteristics, its effect on sperm molecular health is not thoroughly understood. The present study applied next-generation sequencing to investigate the effect of cryopreservation on the sperm transcriptomic composition of bull spermatozoa. While freshly ejaculated bull spermatozoa showed 14,280 transcripts, cryopreserved spermatozoa showed only 12,375 transcripts. Comparative analysis revealed that 241 genes were upregulated, 662 genes were downregulated, and 215 genes showed neutral expression in cryopreserved spermatozoa compared to fresh spermatozoa. Gene ontology analysis indicated that the dysregulated transcripts were involved in nucleic acid binding, transcription-specific activity, and protein kinase binding involving protein autophosphorylation, ventricular septum morphogenesis, and organ development. Moreover, the dysregulated genes in cryopreserved spermatozoa were involved in pathways associated with glycogen metabolism, MAPK signalling, embryonic organ morphogenesis, ectodermal placode formation, and regulation of protein auto-phosphorylation. These findings suggest that the cryopreservation process induced alterations in the abundance of sperm transcripts related to potential fertility-associated functions and pathways, which might partly explain the reduced fertility observed with cryopreserved bull spermatozoa.

Identification of differentially expressed mRNAs and miRNAs in spermatozoa of bulls of varying fertility

Bulls used in artificial insemination, with apparently normal semen quality, can vary significantly in their field fertility. This study aimed to characterize the transcriptome of spermatozoa from high (HF) and low (LF) fertility bulls at the mRNA and miRNA level in order to identify potential novel markers of fertility. Holstein-Friesian bulls were assigned to either the HF or LF group (n = 10 per group) based on an adjusted national fertility index from a minimum of 500 inseminations. Total RNA was extracted from a pool of frozen-thawed spermatozoa from three different ejaculates per bull, following which mRNA-seq and miRNA-seq were performed. Six mRNAs and 13 miRNAs were found differentially expressed (P < 0.05, FC > 1.5) between HF and LF bulls. Of particular interest, the gene pathways targeted by the 13 differentially expressed miRNAs were related to embryonic development and gene expression regulation. Previous studies reported that disruptions to protamine 1 mRNA (PRM1) had deleterious consequences for sperm chromatin structure and fertilizing ability. Notably, PRM1 exhibited a higher expression in spermatozoa from LF than HF bulls. In contrast, Western Blot analysis revealed a decrease in PRM1 protein abundance for spermatozoa from LF bulls; this was not associated with increased protamine deficiency (measured by the degree of chromatin compaction) or DNA fragmentation, as assessed by flow cytometry analyses. However, protamine deficiency was positively and moderately correlated with the percentage of spermatozoa with DNA fragmentation, irrespective of fertility group. This study has identified potential biomarkers that could be used for improving semen quality assessments of bull fertility.

X chromosome-linked genes in the mature sperm influence semen quality and fertility of breeding bulls

The role of sperm expressed X-linked genes on bull fertility has not been studied in detail. The objective of the present study was to assess the influence of X-linked genes on the sperm functional parameters and field fertility rate in the Holstein Friesian cattle (n = 12) and Murrah buffalo (n = 7) bulls. The enrichment analysis (cattle = 8; buffalo = 8) of the X-linked genes was carried out using retrospective RNA-seq data and mRNA expression levels of functionally relevant genes were validated using the RT-qPCR. The mRNA expression levels of these genes were functionally associated with sperm attributes and field fertility rate. The sperm transcriptome studies revealed that the total number of expressed genes and the transcript content of the X-linked genes in the mature sperm were very low in both species, and only 23.31% of these genes were commonly expressed between them. The transcript pool corresponding to the X-linked genes represents embryonic organ development (p = 0.03) and reproduction (p = 0.02) processes in cattle and buffalo sperm, respectively. The mRNA expression levels of X-linked genes, RPL10 and ZCCHC13 in cattle; AKAP4, TSPAN6, RPL10 and RPS4X in buffalo were significantly (p < 0.05) correlated with sperm kinematics. Importantly, the mRNA expression levels of the genes RPL10 (r = -0.68) and RPS4X (r = 0.81) had a significant correlation with the field fertility rate in cattle and buffalo, respectively. Multivariate regression models and receiver operating curve analysis suggest that the mRNA expression levels of X-linked genes may be useful in predicting bull fertility. The study indicates that sperm-expressed X-linked genes influence semen quality and field fertility rate in both cattle and buffalo.

Genom-wide analysis identifies single nucleotide polymorphism variations and altered pathways associated with poor semen quality in breeding bulls

The reason for poor semen quality among the breeding bulls is not well understood. In the present study, we performed high-throughput RNAseq analysis of spermatozoa to identify the SNPs present in good and poor-quality semen-producing Holstein Friesian breeding bulls. A total of 21,360 and 44,650 SNPs were identified in good and poor-quality semen with a minimum read depth of 20, among which 4780 and 8710 novel variants were observed in good and poor-quality semen, respectively. Greater SNPs and indels variations were observed in poor compared to good-quality semen. In poor-quality semen, SNP variations were observed in ZNF280B, SLC26A2, DMXL1, OR52A1, MACROD2 and REV1 genes, which are associated with regulation of spermatogenesis, post-testicular maturation, Cl^- channel activity, V-ATPase-mediated intracellular vesicle acidification, a mono-ADP-ribosyl hydrolase and ATR-Chk1 checkpoint activation. GO analysis of filtered genes with significant variations between good and poor-quality semen showed enrichment in important pathways related to semen quality such as MAPK signalling pathway, Akt signalling pathway, focal adhesion, cAMP signalling pathway, and Rap1 signalling pathway. Network analysis of filtered genes in poor-quality semen showed variations in pathways of purine metabolism, pyrimidine metabolism, prolactin signalling pathway and RNA cap-binding complex. It is inferred that SNP in genes involved in maintaining sperm functions could be the reason for poor-quality semen production in bulls, and the identified SNPs hold potential to be used as biomarkers for semen quality in bulls.

Sperm Transcripts Associated With Odorant Binding and Olfactory Transduction Pathways Are Altered in Breeding Bulls Producing Poor-Quality Semen

Spermatozoa carries a reservoir of mRNAs regulating sperm functions and fertilizing potential. Although it is well recognized that a considerable proportion of high genetic merit breeding bulls produce poor-quality semen, the transcriptomic alterations in spermatozoa from such bulls are not understood. In the present study, comparative high-throughput transcriptomic profiling of spermatozoa from good and poor-quality semen-producing bulls was carried out to identify the transcripts associated with semen quality. Using next-generation sequencing (NGS), we identified 11,632 transcripts in Holstein Friesian bull spermatozoa; after total hit normalization, a total of 544 transcripts were detected, of which 185 transcripts were common to both good and poor-quality semen, while 181 sperm transcripts were unique to good quality semen, and 178 transcripts were unique to poor-quality semen. Among the co-expressed transcripts, 31 were upregulated, while 108 were downregulated, and 46 were neutrally expressed in poor-quality semen. Bioinformatics analysis revealed that the dysregulated transcripts were predominantly involved in molecular function, such as olfactory receptor activity and odor binding, and in biological process, such as detection of chemical stimulus involved in sensory perception, sensory perception of smell, signal transduction, and signal synaptic transmission. Since a majority of the dysregulated transcripts were involved in the olfactory pathway (85% of enriched dysregulated genes were involved in this pathway), the expression of selected five transcripts associated with this pathway (OR2T11, OR10S1, ORIL3, OR5M11, and PRRX1) were validated using real-time qPCR, and it was found that their transcriptional abundance followed the same trend as observed in NGS; the sperm transcriptional abundance of OR2T11 and OR10S1 differed significantly (p < 0.05) between good and poor-quality semen. It is concluded that poor-quality semen showed altered expression of transcripts associated with olfactory receptors and pathways indicating the relationship between olfactory pathway and semen quality in bulls.

K. M, Karthikkeyan G, Prasad TSK, Modi PK, Datta TK, Ramesha K, Manimaran A, Jeyakumar S. Deep Metabolomic Profiling Reveals Alterations in Fatty Acid Synthesis and Ketone Body Degradations in Spermatozoa and Seminal Plasma of Astheno-Oligozoospermic Bulls

Male fertility is extremely important in dairy animals because semen from a single bull is used to inseminate several thousand females. Asthenozoospermia (reduced sperm motility) and oligozoospermia (reduced sperm concentration) are the two important reasons cited for idiopathic infertility in crossbred bulls; however, the etiology remains elusive. In this study, using a non-targeted liquid chromatography with tandem mass spectrometry-based approach, we carried out a deep metabolomic analysis of spermatozoa and seminal plasma derived from normozoospermic and astheno-oligozoospermic bulls. Using bioinformatics tools, alterations in metabolites and metabolic pathways between normozoospermia and astheno-oligozoospermia were elucidated. A total of 299 and 167 metabolites in spermatozoa and 183 and 147 metabolites in seminal plasma were detected in astheno-oligozoospermic and normozoospermic bulls, respectively. Among the mapped metabolites, 75 sperm metabolites were common to both the groups, whereas 166 and 50 sperm metabolites were unique to astheno-oligozoospermic and normozoospermic bulls, respectively. Similarly, 86 metabolites were common to both the groups, whereas 45 and 37 seminal plasma metabolites were unique to astheno-oligozoospermic and normozoospermic bulls, respectively. Among the differentially expressed metabolites, 62 sperm metabolites and 56 seminal plasma metabolites were significantly dysregulated in astheno-oligozoospermic bulls. In spermatozoa, selenocysteine, deoxyuridine triphosphate, and nitroprusside showed significant enrichment in astheno-oligozoospermic bulls. In seminal plasma, malonic acid, 5-diphosphoinositol pentakisphosphate, D-cysteine, and nicotinamide adenine dinucleotide phosphate were significantly upregulated, whereas tetradecanoyl-CoA was significantly downregulated in the astheno-oligozoospermia. Spermatozoa from astheno-oligozoospermic bulls showed alterations in the metabolism of fatty acid and fatty acid elongation in mitochondria pathways, whereas seminal plasma from astheno-oligozoospermic bulls showed alterations in synthesis and degradation of ketone bodies, pyruvate metabolism, and inositol phosphate metabolism pathways. The present study revealed vital information related to semen metabolomic differences between astheno-oligozoospermic and normospermic crossbred breeding bulls. It is inferred that fatty acid synthesis and ketone body degradations are altered in the spermatozoa and seminal plasma of astheno-oligozoospermic crossbred bulls. These results open up new avenues for further research, and current findings can be applied for the modulation of identified pathways to restore sperm motility and concentration in astheno-oligozoospermic bulls.

Comparative Transcriptomic Analysis of Spermatozoa From High- and Low-Fertile Crossbred Bulls: Implications for Fertility Prediction

Crossbred bulls produced by crossing Bos taurus and Bos indicus suffer with high incidence of infertility/subfertility problems; however, the etiology remains poorly understood. The uncertain predictability and the inability of semen evaluation techniques to maintain constant correlation with fertility demand for alternate methods for bull fertility prediction. Therefore, in this study, the global differential gene expression between high- and low-fertile crossbred bull sperm was assessed using a high-throughput RNA sequencing technique with the aim to identify transcripts associated with crossbred bull fertility. Crossbred bull sperm contained transcripts for 13,563 genes, in which 2,093 were unique to high-fertile and 5,454 were unique to low-fertile bulls. After normalization of data, a total of 776 transcripts were detected, in which 84 and 168 transcripts were unique to high-fertile and low-fertile bulls, respectively. A total of 176 transcripts were upregulated (fold change > 1) and 209 were downregulated (<1) in low-fertile bulls. Gene ontology analysis identified that the sperm transcripts involved in the oxidative phosphorylation pathway and biological process such as multicellular organism development, spermatogenesis, and in utero embryonic development were downregulated in low-fertile crossbred bull sperm. Sperm transcripts upregulated and unique to low-fertile bulls were majorly involved in translation (biological process) and ribosomal pathway. With the use of RT-qPCR, selected sperm transcripts (n = 12) were validated in crossbred bulls (n = 12) with different fertility ratings and found that the transcriptional abundance of ZNF706, CRISP2, TNP2, and TNP1 genes was significantly (p < 0.05) lower in low-fertile bulls than high-fertile bulls and was positively (p < 0.05) correlated with conception rate. It is inferred that impaired oxidative phosphorylation could be the predominant reason for low fertility in crossbred bulls and that transcriptional abundance of ZNF706, CRISP2, TNP2, and TNP1 genes could serve as potential biomarkers for fertility in crossbred bulls.

Deciphering the complexity of sperm transcriptome reveals genes governing functional membrane and acrosome integrities potentially influence fertility

Deciphering sperm transcriptome is the key to understanding the molecular mechanisms governing peri-fertilization, embryonic development, and pregnancy establishment. This study aimed to profile sperm transcriptome to identify signature transcripts regulating male fertility. Semen samples were collected from 47 bulls with varied fertility rates. The sperm total RNA was isolated (n = 8) and subjected to transcriptome sequencing. Based on the expression pattern obtained from RNA profiling, the bulls were grouped (p = 0.03) into high-fertile and sub-fertile, and signature transcripts controlling sperm functions and fertility were identified. The results were validated using the OMIM database, qPCR, and sperm function tests. The sperm contains 1100 to 1700 intact transcripts, of which BCL2L11 and CAPZA3 were abundant and associated (p < 0.05) with spermatogenesis and post-embryonic organ morphogenesis. The upregulated genes in the acrosome integrity and functional membrane integrity groups had a close association with the fertility rate. The biological functions of these upregulated genes (p < 0.05) in the high-fertile bulls were associated with spermatogenesis (AFF4 and BRIP1), sperm motility (AK6 and ATP6V1G3), capacitation and zona binding (AGFG1), embryo development (TCF7 and AKIRIN2), and placental development (KRT19). The transcripts involved in pathways regulating embryonic development such as translation (EEF1B2 and MTIF3, p = 8.87E-05) and nonsense-mediated decay (RPL23 and RPL7A, p = 5.01E-27) were upregulated in high-fertile bulls. The identified transcripts may significantly impact oocyte function, embryogenesis, trophectoderm development, and pregnancy establishment. In addition, the study also reveals that the genes governing sperm functional membrane integrity and acrosome integrity have a prospective effect on male fertility.

Sperm-borne small RNAs improve the developmental competence of pre-implantation cloned embryos in rabbit

The low efficiency of somatic cell nuclear transfer (SCNT) greatly limits its application. Compared with the fertilized embryo, cloned embryos display abnormal epigenetic modification and other inferior developmental properties. In this study, small RNAs were isolated, and miR-34c and miR-125b were quantified by real-time PCR; results showed that these micro-RNAs were highly expressed in sperm. The test sample was divided into three groups: one was the fertilized group, one was the SCNT control group (NT-C group), and the third group consisted of SCNT embryos injected with sperm-borne small RNA (NT-T group). The level of tri-methylation of lysine 9 on histone H3 (H3K9me3) at the 8-cell stage was determined by immunofluorescence staining, and the cleavage ratio, blastocyst ratio, apoptotic cell index of the blastocyst and total cell number of blastocysts in each group were analyzed. Results showed that the H3K9me3 level was significantly higher in the NT-C group than in the fertilized group and the NT-T group. The apoptosis index of blastocysts in the NT-C group was significantly higher than that in the fertilized group and the NT-T group. The total cell number of SCNT embryos was significantly lower than that of fertilized embryos, and injecting sperm-borne small RNAs could significantly increase the total cell number of SCNT blastocysts. Our study not only demonstrates that sperm-borne small RNAs have an important role in embryo development, but also provides a new strategy for improving the efficiency of SCNT in rabbit.

Single-molecule long-read sequencing reveals a conserved intact long RNA profile in sperm

Sperm contributes diverse RNAs to the zygote. While sperm small RNAs have been shown to impact offspring phenotypes, our knowledge of the sperm transcriptome, especially the composition of long RNAs, has been limited by the lack of sensitive, high-throughput experimental techniques that can distinguish intact RNAs from fragmented RNAs, known to abound in sperm. Here, we integrate single-molecule long-read sequencing with short-read sequencing to detect sperm intact RNAs (spiRNAs). We identify 3440 spiRNA species in mice and 4100 in humans. The spiRNA profile consists of both mRNAs and long non-coding RNAs, is evolutionarily conserved between mice and humans, and displays an enrichment in mRNAs encoding for ribosome. In sum, we characterize the landscape of intact long RNAs in sperm, paving the way for future studies on their biogenesis and functions. Our experimental and bioinformatics approaches can be applied to other tissues and organisms to detect intact transcripts.

Preliminary comparative deep metabolomic analysis of spermatozoa from zebu and crossbred cattle suggests associations between metabolites, sperm quality and fertility

Poor semen quality and infertility/subfertility are more frequent in crossbred than zebu bulls. Using a high-throughput liquid chromatography–tandem mass spectrometry (LC-MS/MS)-based approach, we established the preliminary metabolomic profile of crossbred and zebu bull spermatozoa (n=3 bulls each) and identified changes in sperm metabolomics between the two groups. In all, 1732 and 1240 metabolites were detected in zebu and crossbred bull spermatozoa respectively. After excluding exogenous metabolites, 115 and 87 metabolites were found to be unique to zebu and crossbred bull spermatozoa respectively whereas 71 metabolites were common to both. In the normalised data, 49 metabolites were found to be differentially expressed between zebu and crossbred bull spermatozoa. The significantly enriched (P&lt;0.05) pathways in spermatozoa were taurine and hypotaurine metabolism (observed metabolites taurine and hypotaurine) in zebu and glycerophospholipid metabolism (observed metabolites phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine) in crossbred bulls. The abundance of nitroprusside (variable importance in projection (VIP) score &gt;1.5) was downregulated, whereas that of l-cysteine, acetyl coenzyme A and 2′-deoxyribonucleoside 5′-diphosphate (VIP scores &gt;1.0) was upregulated in crossbred bull spermatozoa. In conclusion, this study established the metabolomic profile of zebu and crossbred bull spermatozoa and suggests that aberrations in taurine, hypotaurine and glycerophospholipid metabolism may be associated with the higher incidence of infertility/subfertility in crossbred bulls.

Comparison of spermatozoal RNA extraction methods in goats

RNA sequencing (RNAseq) has divulged newer role of spermatozoal RNA in male fertility. This study aimed to evaluate different sperm purification and RNA extraction methods for long-read RNA sequencing of poly(A) transcriptome in goat spermatozoa. Sperm samples were purified by swim-up separation using different purification medium. Spermatozoal RNA was extracted by seven different methods with additional supplementation of reducing agents in lysis buffer. poly(A) selected RNA was used for cDNA library preparation and long-read RNAseq in Nanopore sequencer. Sperm purification by 1 h swim-up resulted in higher recovery (89.20 ± 1.15%), motility (82.33 ± 1.53%), viability (88.10 ± 5.03%) and plasma membrane integrity (71.33 ± 4.51%) in sperm TALP (sp-TL) medium. A monophasic solution of GITC with phenol and DTT resulted in the highest yield of large sized RNAs (3.89 ± 0.46 ng/million cells) suitable for long-read RNAseq of poly(A) transcripts. RNAseq resulted in reads of length, ranging from 500bp to 2 Kb. A total of 123 transcripts were identified in goat spermatozoa by de novo assembly and included sperm-specific transcripts such as CATSPERG, PRM2, CYLC2, SPATA6, PLCZ1 etc. This study is the first report of long-read RNAseq of poly(A) transcriptome in goat spermatozoa.

Orchestrating the expression levels of sperm mRNAs reveals CCDC174 as an important determinant of semen quality and bull fertility

Bulls with acceptable semen quality vary in actual field fertility and this can be elucidated by studying the expression levels of mRNAs in the sperm. The present study aimed at assessing the variations in the sperm gene expression levels of PRM1, CCDC174, RPL36A, TMCO2, SWI5 and OIT3 in bulls differing in fertility status. Frozen semen samples from Holstein-Friesian bulls were classified into high-fertile (n = 8, average field conception rate = 46.1 ± 0.51, p < 0.001) and sub-fertile (n = 7, average field conception rate = 39.4 ± 0.69) groups. In the post-thaw semen samples, sperm kinematics, structural and functional membrane integrities, mitochondrial membrane potential and chromatin distribution were analyzed. The sperm total RNA was subjected to gene expression studies by Real-Time PCR. Multivariate regression analysis was performed using gene expression levels and conception rates. The sperm functional attributes did not differ significantly between the groups. The relative mRNA levels (fold change) of CCDC174 (6.20), RPL36A (4.66), SWI5 (1.86) and OIT3 (1.53) were higher in high-fertile bulls. Further, the expression level of the CCDC174 gene was significantly (p = 0.02) up-regulated in high-fertile bulls. The fertility prediction multivariate model with genes, CCDC174, RPL36A, TMCO2 and OIT3 had the maximum coefficient of determination (R² = 0.68) with the field conception rate. This model had 93.3% bull fertility prediction accuracy with 100% sensitivity and 87.5% specificity. The study suggests that the expression level of CCDC174 can be used as a potential marker for assessing bull fertility.

RNA-Seq analysis reveals functionally relevant coding and non-coding RNAs in crossbred bull spermatozoa

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RNA-Seq analysis was done to characterize the transcriptome of crossbred bull spermatozoa.

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Among the 13,814 transcripts detected, 431 had FPKM > 1 and 13,673 had FPKM > 0 or < 1.

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Coding and non-coding RNAs account for 13,145 (95.15%) and 152 (1.1%), respectively.

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Sperm transcripts were mainly related to ribosome, oxidative phosphorylation and spliceosome pathways.

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qPCR analysis showed individual variations in transcriptional abundance of selected genes.

Sperm, which are believed to be transcriptionally and translationally inactive, synthesize RNA and proteins before there is gradual disappearance of the ribosome during chromatin compaction. Sperm transfer several functionally relevant transcripts to the oocyte, controlling maternal-zygotic transition and embryonic development. The present study was undertaken to profile and analyze sperm transcripts comprehensively using Next Generation Ribonucleic acid sequencing technology in Holstein Friesian x Tharparkar crossbred bulls. The results from global transcriptomic profiling revealed transcripts for 13,814 genes; of which 431 transcripts were expressed with >1 FPKM and 13,383 transcripts were expressed with >0 or <1 FPKM. The abundant mRNA transcripts of crossbred bull sperm were PRM1 and HMGB4. Gene ontology of transcripts with>1 FPKM revealed there was a major involvement in the structural constituent of ribosomes and translation. Results from pathway enrichment indicated the connection between ribosome, oxidative phosphorylation and spliceosome pathways and the transcripts of crossbred bull spermatozoa. The transcriptional abundance of selected genes, validated using RT-qPCR, indicated significant variations between bulls. Collectively, it may be inferred that the transcripts in crossbred bull sperm were heavily implicated in functions such as the structural constituent of ribosomes and translation, and pathways such as ribosome, oxidative phosphorylation and spliceosome. Further studies using larger sample sizes are required to understand the possible implications of transcriptomic variations on semen quality and fertility.

EGF, GDNF, and IGF-1 influence the proliferation and stemness of ovine spermatogonial stem cells in vitro

PURPOSE

The objective of the present study was to purify sheep spermatogonial stem cells (SSCs) from testicular isolate using combined enrichment methods and to study the effect of growth factors on SSC stemness during culture.

METHODS

The testicular cells from prepubertal male sheep were isolated, and SSCs were purified using Ficoll gradients (10 and 12%) followed by differential plating (laminin with BSA). SSCs were cultured with StemPro®-34 SFM, additives, and FBS for 7 days. The various doses (ng/ml) of growth factors, EGF at 10, 15, and 20, GDNF at 40, 70, and 100 and IGF-1 at 50, 100, and 150 were tested for the proliferation and stemness of SSCs in vitro. The stemness in cultured cells was assessed using SSC markers PLZF, ITGA6, and GFRα1.

RESULTS

Ficoll density gradient separation significantly (p < 0.05) increased the percentage of SSCs in 12% fraction (35.1 ± 3.8 vs 11.2 ± 3.7). Subsequently, purification using laminin with BSA plating further enriched SSCs to 61.7 ± 4.7%. GDNF at 40 ng/ml, EGF at 15 and 20 ng/ml and IGF1 at 100 and 150 ng/ml significantly (p < 0.05) improved proliferation and stemness of SSCs up to 7 days in culture. GDNF at 40 ng/ml outperformed other growth factors tested and could maintain the ovine SSCs proliferation and stemness for 36 days.

CONCLUSIONS

The combined enrichment method employing density gradient centrifugation and laminin with BSA plating improves the purification efficiency of ovine SSCs. GDNF at 40 ng/ml is essential for optimal proliferation and sustenance of stemness of ovine SSCs in vitro.

Characterization and functional roles of paternal RNAs in 2-4 cell bovine embryos

Embryos utilize oocyte-donated RNAs until they become capable of producing RNAs through embryonic genome activation (EGA). The sperm's influence over pre-EGA RNA content of embryos remains unknown. Recent studies have revealed that sperm donate non-genomic components upon fertilization. Thus, sperm may also contribute to RNA presence in pre-EGA embryos. The first objective of this study was to investigate whether male fertility status is associated with the RNAs present in the bovine embryo prior to EGA. A total of 65 RNAs were found to be differentially expressed between 2-4 cell bovine embryos derived from high and low fertility sires. Expression patterns were confirmed for protein phosphatase 1 regulatory subunit 36 (PPP1R36) and ataxin 2 like (ATXN2L) in three new biological replicates. The knockdown of ATXN2L led to a 22.9% increase in blastocyst development. The second objective of this study was to characterize the parental origin of RNAs present in pre-EGA embryos. Results revealed 472 sperm-derived RNAs, 2575 oocyte-derived RNAs, 2675 RNAs derived from both sperm and oocytes, and 663 embryo-exclusive RNAs. This study uncovers an association of male fertility with developmentally impactful RNAs in 2-4 cell embryos. This study also provides an initial characterization of paternally-contributed RNAs to pre-EGA embryos. Furthermore, a subset of 2-4 cell embryo-specific RNAs was identified.

Divergence Analyses of Sperm DNA Methylomes between Monozygotic Twin AI Bulls

Semen quality is critical for fertility. However, it is easily influenced by environmental factors and can induce subfertility in the next generations. Here, we aimed to assess the impacts of differentially methylated regions and genes on semen quality and offspring fertility. A specific pair of monozygotic (MZ) twin artificial insemination (AI) Holstein bulls with moderately different sperm qualities (Bull1 > Bull2) was used in the study, and each twin bull had produced ~6000 recorded daughters nationwide in China. Using whole genome bisulfite sequencing, we profiled the landscape of the twin bulls' sperm methylomes, and we observed markedly higher sperm methylation levels in Bull1 than in Bull2. Furthermore, we found 528 differentially methylated regions (DMR) between the MZ twin bulls, which spanned or overlapped with 309 differentially methylated genes (DMG). These DMG were particularly associated with embryo development, organ development, reproduction, and the nervous system. Several DMG were also shown to be differentially expressed in the sperm cells. Moreover, the significant differences in DNA methylation on gene INSL3 between the MZ twin bulls were confirmed at three different age points. Our results provided new insights into the impacts of AI bull sperm methylomes on offspring fertility.

Dietary boron supplementation enhances sperm quality and immunity through influencing the associated biochemical parameters and modulating the genes expression at testicular tissue

INTRODUCTION

Dietary boron improves immune and antioxidant status and calcium metabolism in mammals. However, till date the effects of dietary boron supplementation on male reproduction, especially on sperm production and sperm quality in farm animals are not documented.

OBJECTIVE

The present study was aimed to investigate the influence of dietary boron on semen production, semen quality, immunity and molecular changes in the testis, blood and seminal plasma and to assess the interrelationship with other minerals in male goats.

METHODOLOGY

The study was conducted in 21 adult male goats divided into 3 groups (control, boron and selenium supplemented groups, n = 7 each). In boron group, boron was supplemented at 40 ppm and in selenium group, selenium was supplemented at 1 ppm over and above the basal level. In control group, only the basal diet was fed without supplementary boron or selenium. The feeding trial was carried out for 60 days. Selenium was taken as a positive control for the dietary boron supplementation experiment. Following feeding trials, the sperm concentration, kinematics and functional attributes, immunity and molecular level changes in the testis, biomolecular changes in the blood and seminal plasma and also interrelationship with other minerals were studied.

RESULTS

The average sperm concentration (million/ml) and the total sperm production (million/ejaculate) were significantly (p < 0.05) increased in boron supplemented group when compared to selenium and control groups. The boron levels in blood plasma (r = 0.65) and seminal plasma (r = 0.54) showed a positive correlation with sperm progressive motility. Blood and seminal plasma metabolic biomarker namely, aspartate aminotransferase (AST) (p < 0.01) was significantly lower in the boron and selenium supplemented group than control, while alanine aminotransferase (ALT) (p < 0.05) was significantly lower in the boron supplemented group than selenium and control group. There was a significant increase in the mRNA expression of serine proteinase inhibitor (SERPIN) and interferon γ (IFNγ) in the testis of boron supplemented than the control group. Boron supplementation up-regulated the immune-regulatory gene, interleukin 2 (IL2) and antioxidant gene, catalase (CAT) in the peripheral blood mononuclear cells (PBMC). On contrary, toll-like receptor 2 (TLR2) mRNA expression was significantly (p < 0.05) down-regulated in boron and selenium supplemented groups.

CONCLUSION

The study revealed that dietary boron supplementation increased the sperm output, sperm motility and enhanced the immune and antioxidant defense capacity in male goats. The improved semen quality can be attributed to enhanced expression of testicular SERPIN, a crucial protein for the regulation of spermatogenesis process.

Organic Zn and Cu interaction impact on sexual behaviour, semen characteristics, hormones and spermatozoal gene expression in bucks (Capra hircus)

The reproductive performance during the transition from prepubertal to pubertal stage was evaluated in Osmanabadi breed bucks supplemented with organic Zinc (Zn) and Copper (Cu). A total number of 40 bucks aged 20 weeks were randomly assigned to 10 groups (each n = 4). The control group was maintained with basal diet, without any additional mineral supplementation. The treatment groups were supplemented with graded doses of organic Zn (Zn 20 mg, Zn 40 mg and Zn 60 mg), Cu (Cu 12.5 mg, Cu 25 mg and Cu 37.5 mg) and a combination of Zn + Cu (Zn 20 mg + Cu 12.5 mg, Zn 40 mg + Cu 25 mg and Zn 60 mg + Cu 37.5 mg), respectively for a period of 26 weeks (up to the age of 46 weeks). Sexual behaviour and scrotal biometry were recorded periodically. Blood and semen samples were collected and processed for LH estimation in blood plasma, and testosterone, T3 and T4 hormones in the seminal plasma. The mounts with ejaculation were observed earlier (P < 0.05) in the treatment bucks (from 38th week of age) than the control group (43rd week onwards). A positive correlation was observed between blood plasma LH and testosterone with total mounts (r = 0.31, P < 0.05; r = 0.51, P < 0.01) and mounts without ejaculation (r = 0.40, P < 0.01; r = 0.52, P < 0.01). A negative correlation between T4 with sperm number per ejaculation (r = -0.31, P < 0.05) and sperm concentration (r = -0.35, P < 0.05) had been noticed. Different doses of minerals showed positive interaction (P < 0.05) with sperm functional and behavioural characteristics. The spermatozoal gene expression of ODF2 and ZCCHC6 were significantly influenced by the mineral supplementation in all doses. The ZCCHC6 gene expression was positively correlated with testosterone (r = 0.50, P < 0.001) and sperm number per ejaculation (r = 0.42, P < 0.001), and ODF2 gene with T3 hormone (r = 0.34, P < 0.05). The present study indicates that the diet supplemented with organic trace minerals cause intense sexual behaviour, enhancement in sperm number per ejaculate, total motility, spermatozoal genes expression and altered LH, testosterone and T4 hormones.

Database on spermatozoa transcriptogram of catagorised Frieswal crossbred (Holstein Friesian X Sahiwal) bulls

Bull spermatozoa contain different functional genes and many of them plays important roles in different stages of spermatogenesis, spermatozoa kinetics, fertilization as well as embryonic development. RNA deep sequencing is one of the preferred tools for absolute quantification of messenger RNA. The intention of the current study was to investigate the abundance of spermatozoal transcripts in categorized Frieswal (Holstein-Friesian X Sahiwal) crossbred bull semen through RNA deep sequencing. A total 1546561 and 1019308 numbers of reads were identified among good and poor quality bull spermatozoa based on their conception rate. Post mapping with Bos taurus reference genome identified 1,321,236 and 842,022 number of transcripts among good and poor quality RNA libraries, respectively. However, a total number of 3510 and 6759 functional transcripts were identified among good and poor quality bull spermatozoa, respectively. Most of the identified transcripts were related to spermatozoa functions, embryonic development and other functional aspects of fertilization. Wet laboratory validation of the top five selected transcripts (AKAP4, PRM1, ATP2B4, TRIM71 and SLC9B2) illustrated the significant (p < 0.01) level of expression in the good quality crossbred bull semen than the poor quality counterparts. The present study with comprehensive profiling of spermatozoal transcripts provides a useful non-invasive tool to understand the causes of as well as an effective way to predict male infertility in crossbred bulls.

Patterns of expression of sperm and seminal plasma microRNAs in boar semen

Although sperm and seminal plasma differ in their origin, biophysical and biochemical properties of seminal plasma influence the sperm function. Seminal plasma is a fluid medium containing substances from testes, epididymides and accessory glands. Composition of seminal plasma varies among animal species and in boars, prostate and bulbourethral glands are major contributors to the volume and contents. While the origin of some components of seminal plasma are known, the source of recently discovered seminal plasma microRNAs remains unknown, in part due to the difficulty of recovering and characterizing RNA from porcine sperm and seminal plasma. To test the hypothesis that seminal plasma miRNAs interact with sperm, the first objective was to validate protocols for recovering RNAs from porcine seminal plasma and sperm, whereas the second objective was to characterize expression patterns of 84 prioritized microRNAs employing real time PCR methodology. The study identified a relationship between sperm and seminal plasma microRNAs, based on the normalized threshold cycle of amplifying cDNA in sperm and seminal plasma from the same semen of Landrace boars. Therefore, it was concluded that seminal plasma miRNAs may originate from sperm or these miRNAs may shuttle between sperm and seminal plasma in order to facilitate cell-to-cell communication.

Relationship of organic mineral supplementation and spermatozoa/white blood cells mRNA in goats

The antioxidant properties and the protective role of organic zinc (Zn) and copper (Cu) in white blood cells (WBCs) and spermatozoa were analyzed through quantification of superoxide dismutase 1 (SOD1), catalase (CAT), glutathione peroxidase 4 (GPx4) and nuclear factor erythroid 2-like 2 (NFE2L2) and correlations were determined with sperm functional characteristics in Osmanabadi bucks. Bucks (aged 5 months; n = 40) were divided into ten groups, and the dietary treatments comprised of a control and nine treatment groups as follows: organic Zn as Zn 20, Zn 40 and Zn 60, organic Cu as Cu 12.5, Cu 25, Cu 37.5 and combined organic Zn and Cu as Zn 20+Cu 12.5, Zn 40+Cu 25, Zn 60+Cu 37.5, respectively per kg dry matter for a period of 8 months. The blood (120 and 240 days) and semen (240 days: 40 × 4 = 160) samples were collected from 40 bucks. In WBCs: the relative abundance of mRNA for SOD1, CAT, GPx4, NFE2L2 was greater (P < 0.05) in (120 and 240 days) in majority of the mineral supplemented animals. In spermatozoa: the relative abundance of SOD1, NFE2L2, GPx4 and CAT mRNA was greater (P < 0.05) in selected treatment groups. The abundance of SOD1 mRNA in WBCs was positively correlated (P <  0.05) with sperm mass motility (r = 0.692, P = 0.027). The abundance of GPx4 mRNA was negatively correlated (P <  0.05) with type A sperm (straightness; STR) > 85% and amplitude of lateral head displacement (ALH) > 2.5 μm/ s) (r = -0.711, P = 0.021) and (P <  0.05) positively correlated with sperm viability (r = 0.669, P = 0.035). Organic Zn and Cu supplementation was associated with an increase in the expression of antioxidant defense enzyme genes in bucks.

Occurrence and functional significance of the transcriptome in bovine (Bos taurus) spermatozoa

Mammalian spermatozoa deliver various classes of RNAs to the oocyte during fertilization, and many of them may regulate fertility. The objective of the present study was to determine the composition and abundance of spermatozoal transcripts in fresh bull semen. The entire transcriptome of the spermatozoa from bulls (n = 3) was sequenced using two different platforms (Ion Proton and Illumina) to identify the maximum number of genes present in the spermatozoa. The bovine spermatozoa contained transcripts for 13,833 genes (transcripts per million, TPM > 10). Both intact and fragmented transcripts were found. These spermatozoal transcripts were associated with various stages of spermatogenesis, spermatozoal function, fertilization, and embryo development. The presence of intact transcripts of pregnancy-associated glycoproteins (PAGs) in the spermatozoa suggest a possible influence of sperm transcripts beyond early embryonic development. The specific regions (exon, intron, and exon-intron) of the particular spermatozoal transcripts might help regulate fertilization. This study demonstrates that the use of two different RNA-seq platforms provides a comprehensive profile of bovine spermatozoal RNA. Spermatozoal RNA profiling may be useful as a non-invasive method to delineate possible causes of male infertility and to predict fertility in a manner that is more effective than the conventional methods.

SpermBase: A Database for Sperm-Borne RNA Contents

Since their discovery approximately three decades ago, sperm-borne RNAs, both large/small and coding/noncoding, have been reported in multiple organisms, and some have been implicated in spermatogenesis, early development, and epigenetic inheritance. Despite these advances, isolation, quantification, and annotation of sperm-borne RNAs remain nontrivial. The yields and subspecies of sperm-borne RNAs isolated from sperm can vary drastically depending on the methods used, and no cross-species analyses of sperm RNA contents have ever been conducted using a standardized sperm RNA isolation protocol. To address these issues, we developed a simple RNA isolation method that is applicable to sperm of various species, thus allowing for reliable interspecies comparisons. Based on RNA-Seq analyses, we established SpermBase ( www.spermbase.org), a database dedicated to sperm-borne RNA profiling of multiple species. Currently, SpermBase contains large and small RNA expression data for mouse, rat, rabbit, and human total sperm and sperm heads. By analyzing large and small RNAs for conserved features, we found that many sperm-borne RNA species were conserved across all four species analyzed, and among the conserved small RNAs, sperm-borne tRNA-derived small noncoding RNAs and miRNAs can target a large number of genes known to be critical for early development.