Expression of transforming growth factor-beta isoforms and their receptors in utero-vaginal junction of hen oviduct in presence or absence of resident sperm with reference to sperm storage

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.

Investigating the genetic determination of duration-of-fertility trait in breeding hens

The duration-of-fertility (DF), which was defined as the number of days when breeding hens lay fertile eggs following copulation or artificial insemination (AI), is an important economic trait in chick production when it has strong effects on fertile egg output and production costs. Little is known about the underlying genes and molecular markers related to DF trait to date. Here, we measured the DF of 701 Chinese Jinghong hens and 408 Jingfen hens. The DF showed high individual variability and potential for genetic improvement. Then, 192 Jinghong breeding hens were provided for a genome-wide association study, 27 SNPs respectively located in three genomic linkage regions (GGA1:41Kb; GGA3:39Kb and GGA8:39Kb) were suggested to be significantly associated with DF. Particularly, 6 of these 27 SNPs were further verified to be associated with DF in the 701 Jinghong and 408 Jingfen hens using PCR-RFLP genotyping method. These 27 SNPs were also mapped to 7 genes according to their genomic position. Furtherly, 5 of these 7 genes were tested using qPCR. Results show that the CYP2D6, WBP2NL, ESR1 and TGFBR3 mRNA expression levels of hens with long DF were significantly higher than the hens with short DF (P < 0.05). Overall, findings in our research provide new insight into the genetic basis of duration-of-fertility in breeding hens while providing new clues for further functional validation on the DF-related genetic regulation mechanism and improvement of DF through chicken breeding.

Effects of dietary supplementation of tomato pomace (Solanum lycopersicum L.) and L-Arg on reproductive performance of aged male broiler breeders

This study aimed to investigate the effects of different dietary supplementation of tomato pomace (TP) and L-arginine (L-Arg) supplementation on sperm characteristics, reproductive performance, and semen biochemical components of aged commercial male broiler breeders. Thirty Ross 308 male broiler breeders (58 wk old) were provided and assigned to 5 dietary treatment groups, including control (CON), 5% TP (TPS-5), 10% TP (TPS-10), 15% TP (TPS-15), and L-Arg supplemented (10% above the recommendation, LAS-10). The results indicated that the semen volume increased in the TPS-15 group compared to that of the LAS-10 (and CON on wk 9) throughout the study (P < 0.05). The sperm concentration significantly increased in TPS-10 and TPS-15 groups in comparison to the other experimental groups. On wk 5 and 7, the sperm viability increased in all TPS groups compared to the CON and LAS-10, while on wk 9, it only increased in the TPS-10 group in comparison to the LAS-10 group (P < 0.05). The hypo-osmotic swelling test decreased in the LAS-10 group compared to the other experimental groups on wk 5 and all TPS groups on wk 7 and 9 (P < 0.05). The sperm total motility and forward progressive motility decreased in the LAS-10 group compared to the other experimental groups (P < 0.05). In contrast, unprogressive motility and immotile sperms were increased in the LAS-10 group compared to the other experimental groups (P < 0.05). In addition, the sperm penetration and fertility rate increased in TPS-10 and TPS-15 groups in comparison to CON and LAS-10 groups (P < 0.05). However, hatchability was reduced in the LAS-10 group (P < 0.05). The semen adenosine triphosphate increased in TPS-10, TPS-15, and LAS-10 groups compared to the CON (P < 0.05). Finally, the semen TAC and superoxidase dismutase decreased in the LAS-10 group (P < 0.05), while the glutathione peroxidase increased in the TPS-15 group (P < 0.05). In conclusion, 15% dietary TPS is recommended to improve the reproductive performance of aged commercial male broiler breeders.

Sperm storage by females across the animal phyla: A survey on the occurrence and biomolecules involved in sperm storage

Long-term sperm storage by females in various regions of the oviduct is documented across many invertebrate and vertebrate species. Although, many reports emphasize on the histology, histochemistry and ultrastructural features of sperm storage, very little is known about the mechanisms underlying the sperm storage. The current review documents the occurrence of sperm storage by females in a wide array of invertebrate and vertebrate species. This review also provides an insight on the presence of various molecular factors of the sperm storage tubules presumably responsible for the prolonged sperm storage with an emphasis on a model reptile, the Indian garden lizard, Calotes versicolor which contains a unique approximately 55-kDa protein in its utero-vaginal lavage and found to inhibit washed epididymal sperm motility in a concentration and time-dependent manner in a reversible fashion.

Differential gene expression analysis related to sperm storage in spermathecas of Amphioctopus fangsiao

Sperm storage in the female body is an important strategy in animal reproductive behavior. Amphioctopus fangsiao is an economically important cephalopod that has a sperm storage period of up to seven months. There are few studies concerning the mechanism of sperm storage in A. fangsiao. In this study, we performed transcriptome gene expression profiling of the oviductal glands at different phases (presence and absence of sperm storage). In total, 7943 differentially expressed genes (DEGs) comprising 4737 upregulated and 3206 downregulated genes were identified. GO and KEGG enrichment analyses were used to search for sperm storage-related genes. A protein interaction network was constructed to examine the interactions between genes. Nineteen genes associated with immunity, apoptosis, and autophagy were obtained and verified by qRT-PCR. This is the first comprehensive analysis of sperm storage-related genes in A. fangsiao. The results provide basic insights into the complex sperm storage mechanism of A. fangsiao.

Transcriptome analysis of inseminated sperm storage tubules throughout the duration of fertility in the domestic turkey, Meleagris gallopavo

Sperm storage tubules (SST) are specialized invaginations of the oviductal epithelium that permit avian species to store spermatozoa for extended periods of time, without compromising sperm fertilization capacity. The molecular and physiological mechanisms behind sperm storage tubule differentiation, sperm protection, and regression remain largely unknown, but most likely have potential implications for substantially improving hen fertility, sperm storage, and semen cryopreservation in commercial poultry species. RNA sequencing was performed on sperm storage tubules isolated from the epithelium of the uterovaginal junction (UVJ) from hens at d 1, 7, 30, 60, and 90 postinsemination (n = 4 per timepoint). Read mapping and differential expression analysis were performed using CLC Genomics Workbench. A total of 2,340 differentially expressed genes were subjected to pathway analysis through Ingenuity Pathway Analysis (IPA). Through functional annotation of differentially expressed genes during early, peak, and late egg production, novel insights regarding the role of innate and acquired immune response to sperm, lipid synthesis and transfer, steroid hormone signalling, cytoskeletal reorganization, and regulation of ion homeostasis in SST were obtained. Additionally, potential pathways were identified that could be involved with suppressing sperm motility while sperm reside within the SST. Upstream analysis identified potential regulatory roles for 18 upstream regulators that could modulate sperm storage tubule function, including suppression of sperm motility. Understanding sperm storage tubule function throughout the laying cycle, especially with regards to sperm preservation may allow for the development of industry-based protocols for semen storage and cryopreservation that mimic the sperm preservation capabilities of SST and improve fertility.

Transcriptomic and metabolomic insights into the variety of sperm storage in oviduct of egg layers

In birds, the sperm storage tubules (SST) are dispersed in uterovaginal junction (UVJ) and highly correlated with differential capacity of sperm storage (SS) in and among species with unspecified mechanisms. Here, the SS duration of 252 egg layer breeders was evaluated in 5 rounds with 3 phenotypic traits to screen high- and low-SS individuals, respectively, followed with transcriptome of UVJ tissues and metabolome of serum (high-SS vs. low-SS) to decipher the candidate genes and biochemical markers correlated with differential SS capacity. Histological characterization suggested slightly higher density of SST in UVJ (high-SS vs. low-SS). Transcriptome analyses identified 596 differentially expressed genes (336 upregulated vs. 260 downregulated), which were mainly enriched in gene ontology terms of homeostasis, steroid and lipid metabolism and hormone activity, and 12 significant pathways (P < 0.05) represented by calcium, steroid, and lipid metabolism. Immunohistochemical staining of GNAQ, ST6GAL1, ADFP, and PCNA showed similar distribution in UVJ tissues between 2 groups. Several candidates (HSD11B2, DIO2, AQP3, GNAQ, NANS, ST6GAL1) combined with 4 (11β-prostaglandin F2α, prostaglandin B1, 7α-hydroxytestosterone, and N-acetylneuraminic acid) of 40 differential metabolites enriched in serum metabolome were considered as regulators and biomarkers of SS duration in egg layer breeders. The integrated transcriptome and metabolome analyses of chicken breeder hens will provide novel insights for exploration and improvement of differential SS capacity in birds.

Transcriptome analysis and identification of age-associated fertility decreased genes in hen uterovaginal junction

Avian sperm storage tubules (SSTs), which are located in the uterovaginal junction (UVJ) of the oviduct, are primary sperm storage sites after mating or artificial insemination. The mechanism underlying reduced sperm storage efficiency of SSTs which is highly correlated with decreased fertility rates in aged laying breeders remains largely unclear. Here, comparative transcriptomic analysis between the aged and young White Leghorn hens (120 vs. 30 wk) was applied to identify gene expression changes of UVJs containing SSTs. Bioinformatics analysis revealed 567 upregulated and 1998 downregulated differentially expressed genes. Gene ontology analysis was highly enriched in terms of immune system, cell adhesion, and cytoskeleton proteins. Kyoto Encyclopedia of Genes and Genomes analysis revealed 5 significant (P < 0.05) pathways including inositol phosphate and glycerophospholipid metabolism. β-Galactosidase staining of chicken UVJ sections suggested increased cell senescence via aging. Oil Red O staining and immunohistochemistry detection of ADFP both confirmed distribution of lipid droplets in SST cells with increased intensity in aged breeders. The lipid synthesis and metabolism-related genes represented by TFAP2 and PLD1 were differentially expressed in aged laying breeders. The upregulation of IL15 and downregulation of a large number of immune-related genes in aged breeders indicate altered immune homeostasis in UVJs and SSTs. The increased accumulation of lipids, and altered immunity homeostasis, combined with other factors (TJP1, MYL9, AFDN, and RPL13, etc.) are potentially dominant effectors to decrease the sperm storage efficiency and egg fertility in aged laying breeders.

Reproductive consequences of an extra long-term sperm storage organ

Background

Sperm storage plays a key role in the reproductive success of many sexually-reproducing organisms, and the capacity of long-term sperm storage varies across species. While there are theoretical explanations for why such variation exists, to date there are no controlled empirical tests of the reproductive consequences of additional long-term sperm storage. While Dipterans ancestrally have three long-term sperm organs, known as the spermathecae, Drosophila contain only two.

Results

We identified a candidate gene, which we call spermathreecae (sp3), in which a disruption cause the development of three functional spermathecae rather than the usual two in Drosophila. We used this disruption to test the reproductive consequences of having an additional long-term sperm storage organ. Compared to females with two spermathecae, females with three spermathecae store a greater total number of sperm and can produce offspring a greater length of time. However, they did not produce a greater total number of offspring.

Conclusions

Thus, additional long-term sperm storage in insects may increase female fitness through extending the range of conditions where she produces offspring, or through increasing the quality of offspring via enhanced local sperm competition at fertilization.

Effect of crocin and naringenin supplementation in cryopreservation medium on post-thaw rooster sperm quality and expression of apoptosis associated genes

The aim of our study was to examine the effects of crocin (0.5 (C0.5), 1 (C1) and 1.5 (C1.5) mM) and naringenin (50 (N50), 100 (N100) and 150 (N150) μM) in cryopreservation extender for freezing rooster semen. Sperm motility, viability, abnormalities, membrane functionality, active mitochondria, apoptosis status, lipid peroxidation (LP), GPX, SOD, TAC, the mRNA expression of pro-apoptotic (CASPASE 3) and anti-apoptotic (Bcl-2) genes, fertile eggs, hatched eggs and hatching rate were investigated following freeze-thawing. C1 and N100 resulted in higher (P < 0.05) total motility and progressive motility in comparison to the control group. The C1 and N100 groups improved viability, membrane functionality and reduced lipid peroxidation. We found higher values for active mitochondria with C1 and N100 compared to control group. The C1 and N100 groups showed lower percentages of early apoptosis when compared with control group. Also, C1 and N100 had higher TAC, compared to the control group. The mRNA expressions of BCL-2 in the C1 and N100 groups were significantly higher than that of other treatments. The expression of CASPASES 3 was significantly reduced in C1 and N100 group (P < 0.05) when compared to control group. Significantly higher percentages of fertile eggs, hatched eggs and hatching rate were observed in C1 and N100 compared to the control group. In conclusion, crocin at 1 mM and naringenin at 100 μM seem to improve the post-thawing rooster semen quality, fertility and could protect the sperm by reducing the pro-apoptotic (CASPASE 3) and increasing anti-apoptotic (Bcl-2) genes.

Does the Act of Copulation per se, without Considering Seminal Deposition, Change the Expression of Genes in the Porcine Female Genital Tract?

Semen—through its specific sperm and seminal plasma (SP) constituents—induces changes of gene expression in the internal genital tract of pigs, particularly in the functional sperm reservoir at the utero-tubal junction (UTJ). Although seminal effects are similarly elicited by artificial insemination (AI), major changes in gene expression are registered after natural mating, a fact suggesting the act of copulation induces per se changes in genes that AI does not affect. The present study explored which pathways were solely influenced by copulation, affecting the differential expression of genes (DEGs) of the pre/peri-ovulatory genital tract (cervix, distal uterus, proximal uterus and UTJ) of estrus sows, 24 h after various procedures were performed to compare natural mating with AI of semen (control 1), sperm-free SP harvested from the sperm-peak fraction (control 2), sperm-free SP harvested from the whole ejaculate (control 3) or saline-extender BTS (control 4), using a microarray chip (GeneChip^® porcine gene 1.0 st array). Genes related to neuroendocrine responses (ADRA1, ADRA2, GABRB2, CACNB2), smooth muscle contractility (WNT7A), angiogenesis and vascular remodeling (poFUT1, NTN4) were, among others, overrepresented with distal and proximal uterine segments exhibiting the highest number of DEGs. The findings provide novel evidence that relevant transcriptomic changes in the porcine female reproductive tract occur in direct response to the specific act of copulation, being semen-independent.

Effects in broiler hens of genetic lines differing in fertility, biotin supplementation, and age on relative abundance of oviductal transforming growth factor-β and carbonic anhydrase mRNA transcripts

There was evaluation of effects of biotin administration on oviductal abundance of transforming growth factor-β (TGF-β) and carbonic anhydrase (CA) mRNA transcript in younger and older broiler hens of relatively lesser and greater fertility lines. Additionally, effects of biotin supplementation on attenuation of age-related subfertility were evaluated. Hens from the relatively greater (Line D, n = 60) and lesser (Line B, n = 60) fertility rate line were randomly assigned to three treatment groups. Biotin was not or was administered in drinking water from 30 to 33 (younger age) and 53 to 56 (older age) wk of age to have access to no biotin (T₀), or 0.3 (T₁), or 0.45 (T₂) mg/L of biotin. There was assessment the relative oviductal abundances of TGF-β and CA mRNA transcript abundances. Supplemental biotin and age had no effect on the relative abundance of oviductal TGF-β mRNA transcript in hens of Line D. There, however, was a ten-fold greater abundance of TGF-β in hens of the T₀ group of Line B compared with Line D. Relative abundance of TGF-β mRNA transcript was greater in younger hens of Line B; however, biotin supplementation of older hens of the T₂ group of Line B resulted in a similar TGF-β abundance to that of younger hens. Inconstant with the TGF-β abundance, CA abundance in hens of Line B was not affected by supplemental biotin or bird age. Overall, differences in TGF-β or CA abundances did not affect fertility of broiler hens.

A genome-wide single nucleotide polymorphism scan reveals genetic markers associated with fertility rate in Chinese Jing Hong chicken

The function of the sperm storage tubules is directly correlated with the fertility of laying hens. However, little is known about the molecular mechanisms regulating the fertility traits in chicken. To identify genetic markers associated with reproductive traits, we calculated fertility rate at 61 to 69 wk (51 D) of Jing Hong chickens parent generation as the phenotype and the genotype were detected by the chicken 600K Affymetrix Axiom High Density single nucleotide polymorphisms (SNP)-array. The genome-wide association study using 190 Jing Hong hens showed that the 20 SNP in chromosomes 3 and 13 were significantly associated with fertility rate. To verify these results, a total of 1900 Jing Hong laying hens from 2 populations (P1 and P2) were further genotyped by polymerase chain reaction-restriction fragments length polymorphisms method. The association analysis results revealed that 12 polymorphisms (AX-75769978, AX-76582632, AX-75730546, AX-75730496, AX-75730588, AX-76530282, AX-76530329, AX-76529310, AX-75769906, AX-75755394, AX-80813697 and AX-76582809) out of 20 showed highly significant effects (P < 0.0001) on fertility rate in P1, P2 and P1+P2. Six haplotypes (TTAA, TTGG, TTAG, CTAA, CTGG, and CTAG) were inferred based on significant loci (AX-75730546 and AX-76530282) also showed significant association with fertility rate, where haplotype CTAG was shown to be markedly associated with the significantly highest (P < 0.0001) fertility rate (in P1, 86.42 ± 0.59; P2, 85.98 ± 0.59 and P1+P2, 86.16 ± 0.42) followed by other haplotypes for the irrespective of population studied. Collectively, we report for the first time that 12 SNP in the chromosomes 3 and 13 were significantly associated with fertility rate during the later stage of egg production, which could be used as the potential genetic markers that would be able to facilitate in the selection and improvement of fertility rate through chicken breeding.

Investigation of the impact of gut microbiotas on fertility of stored sperm by types of hens

Owing to the practical interest in understanding duration of fertility (DF) to reduce the cost of producing hatching eggs by decreasing the frequency of artificial insemination, as well to uncover the mechanism of the estrogen-gut microbiome axis, elucidating the interaction between the maternal microbiome and the function of sperm storage tubules (SST) has become important for revealing the DF in laying hens. In this study, we investigated the compositional, structural, and functional differences in gut microbiomes between hens with high (HSST, n = 8) and low SST activity (LSST, n = 10) by performing phenotypic selection from approximately 400 individual hens based on their DFs. Their cecal microbial communities were analyzed by sequencing the V4 region of the 16S rRNA gene. The microbiome abundance estimators from the ceca of HSST and LSST hens were not significantly different at the phylum and genus taxonomic levels, although the relative abundances for the phylum Firmicutes and the genus Lactobacillus were higher in the HSST group. Furthermore, some taxonomic levels of bacteria expressing the components of several metabolic pathways differed between the HSST and LSST groups. Moreover, predicting functional microbiomes by Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that certain pathways, such as the metabolism of carbohydrates and protein, cellular processes, and organismal systems, of the HSST group exhibited higher expression of genes associated with bioactivity and energy biosynthesis than those in the LSST group. Our results may provide insights into hen-microbe interactions with respect to DF and will be useful in establishing a strategy for new research to uncover the functional regulation of SST in laying hens.

Down-regulation of TGF-β, VEGF, and bFGF in vascular endothelial cells of chicken induced by a brittle star (Ophiocoma erinaceus) extract

Great attention has been focused on the discovery of anti-angiogenic natural and synthetic compounds to be finally used as or at least a part of the treatment of tumors. The marine ecosystems provide diversity in natural chemicals with the potential of being exploited as medicines in the treatment of diseases. Several studies have investigated Ophiuroids as a source of anti-tumor and anti-metastatic organisms. Here, we described the inhibitory effects of an ethanolic crude extract of brittle star (Ophiocoma erinaceus) on angiogenesis and the expression level of TGF-β, VEGF, and bFGF in chicken chorioallantoic membrane (CAM) as an experimental model. To do this 45 embryonated eggs were randomly divided into six groups including the control group, sham, three experimental groups and positive. The number and the length of vessels were calculated using ImageJ® software. The relative mRNA levels of the genes in different groups were evaluated by qRT-PCR method. Our study was suggestive of an anti-angiogenesis effect of brittle star ethanolic crude extract in a CAM model. The extract also showed a pharmacological effect of down-regulation of mRNA related to VEGF, TGF-β, and bFGF genes on chicken vascular endothelial cells. It was also showed that the observed inhibitory effect is with a dose-dependent manner in which the highest inhibitory effect belonged to the highest used dose. We indicated the anti-angiogenesis properties of the Persian Gulf brittle star. Further studies are needed in other aspects of the brittle star extract in the treatment of angiogenesis, hyperplasia, and cancers.

Expression of Transferrin and Albumin in the Sperm-Storage Tubules of Japanese Quail and their Possible Involvement in Long-Term Sperm Storage

Because of the presence of sperm storage tubules (SSTs) in the utero-vaginal junction (UVJ) in the oviduct, once ejaculated sperm enter the female reproductive tract, they can survive for a prolonged period in domestic birds; however, the specific mechanisms involved in sperm maintenance within the SST remain to be elucidated. In this study, we showed that transferrin (TF) and albumin (ALB) are expressed in SSTs. When UVJ extracts were subjected to size-exclusion column chromatography, we obtained fractions that extend sperm longevity in vitro. LC-MS/MS analysis of the two major proteins in the fractions identified these proteins as TF and ALB. Immunohistochemical analysis using specific antisera against TF and ALB indicated that both proteins were localized not only in the SSTs, but also in the surface epithelium of the UVJ. When the ejaculated sperm were incubated with either purified TF or ALB, sperm viability increased after 24 h. These results indicated that oviductal TF and ALB are involved in the process of sperm storage in SSTs and may open a new approach for technological improvement to prolong sperm longevity in vitro.

Use of supplemental dietary coenzyme Q10 to improve testicular function and fertilization capacity in aged broiler breeder roosters

In numerous studies it has been suggested that targeting mitochondria with specific compounds could efficiently inhibit various conditions associated with oxidative stress. The treatment of aged roosters with compounds such as coenzyme Q10 (CoQ10), may improve their reproductive performance by providing protection from oxidative stress. Therefore, this study was performed to assess the effect of supplemental dietary CoQ10 on the testicular function and fertility of aged broiler breeder roosters. A total of 36 roosters)47 weeks of age) were randomly divided into dietary treatments containing either 0, 300 or 600 mg CoQ10/kg diet. Three birds were allocated to each of four replicate groups in each dietary treatment. Between 47 and 54 weeks of age, ejaculates were obtained weekly from the three roosters in each replicate group. Samples in a replicate were pooled and analyzed as a single sample. Between 51 and 54 weeks of age, seminal plasma total antioxidant capacity (TAC), alanine amino transferase (ALAT) and aspartate amino transferase (ASAT) levels were assessed. Fertility, hatchability, and sperm penetration (SP) rates were likewise evaluated. Seminal volume, sperm concentration, sperm plasma membrane functionality, sperm plasma membrane integrity, seminiferous tubule diameter and seminiferous epithelium thickness exhibited quadratic increases in response to increasing levels of dietary CoQ10. Respectively, the 429.19, 433.33, 464.50, 613.50, 392.78 and 447.99 mg/kg dietary concentrations of CoQ10 provided the best results for each of the aforementioned variables. Also, other seminal traits, as well as testosterone concentration, fertility, and SP rates, displayed linear increases in response to the increasing levels of CoQ10. Dietary supplementation of CoQ10 linearly decreased seminal plasma ALAT and ASAT and linearly increased seminal plasma TAC. In conclusion, CoQ10 supplementation in the diet (a minimum of 300 mg CoQ10/kg diet) has the potential to improve the reproductive performance of aged broiler breeder roosters.

Association of single nucleotide polymorphism at long non-coding RNA 8138.1 with duration of fertility in egg-laying hens

A previous genome-wide transcriptional analysis identified long non-coding RNA 8138.1 (lncRNA8138.1) as a candidate gene related to hen duration of the fertility (DF) trait. LncRNA8138.1 gene response to growth factor and reproductive system development suggests it has a vital role in reproduction. In this study, we investigated the lncRNA8138.1 gene sequence in a population of egg-laying hens. The sequence analysis of the lncRNA8138.1 gene containing about 1.6 k nucleotides (nt) was observed with four single nucleotide polymorphisms (SNPs) and 7 nt indel including r.4937159A > G; r.4937219T > C; r.4937258G > C; r.4937318C > G and g.4937319_4937325delinsTGTGTGG. Next, the genomic DNAs from laying hen populations were subjected to polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) to detect a region of 457 bp carrying lncRNA8138.1 r.4937159A > G substitution. Further inspection of the region containing r.4937159A > G mutation revealed three genotypes viz., AA, AG, and GG were observed with respective frequencies of 0.106, 0.607, and 0.287 in laying hen population 1 (P1) (n = 1, 042) and respective frequencies of 0.176, 0.708, and 0.116 in laying hen population 2 (P2) (n = 826). Moreover, to further examining the frequencies of r.4937159A > G genotypes in P1 and P2, and their additive and dominance effects; r.4937159A > G locus was significantly associated with DF-trait in both P1 and P2 (EN: the number of eggs, FN: the number of fertile eggs after a single AI), and DN (the number of days post-insemination until last fertile egg). In testing for additive and dominance effects, additive effect was significant (P < 0.05) in both P1 and P2 for DF-trait, and the dominance effect was significant (P < 0.05) for EN and FN traits, suggesting that r.4937159A > G polymorphism is a potential biomarker for DF-trait. However, the identified novel r.4937159A > G mutation and others require further investigation to confirm phenotypic causality and potential genetic relationships with reproductive traits. Overall, our findings suggest the significance of genetic variation in long non-coding RNAs may assist in future breeding programs to improve selection for prolonged DF-trait.

Role of genome-wide mRNA-seq profiling in understanding the long-term sperm maintenance in the storage tubules of laying hens

Sperm storage function of the sperm storage tubules (SSTs) is directly correlated with the fertility of laying hens. SSTs are located at the utero-vaginal junction (UVJ) and infundibulum of the hen oviduct. However, little is known about the cellular and molecular mechanisms responsible for long-term sperm maintenance in the lumen of the SSTs. In this study, we profiled transcriptomes to detect the different gene expressions between infundibulum and UVJ using RNA-seq. As a result, we identified a total of 1382 differentially expressed genes (DEGs). GO analysis showed that fat acid metabolism, regulation of cell differentiation, regulation of transport, and immune response were enriched for these DEGs, and many of the pH-regulatory functions genes such as CAIV and SLC4A4 were highly expressed in UVJ, which inferred that SSTs could preserve sperm by regulating physiological functions in UVJ. Our results provide new insight to understand the specific function for SSTs to extend sperm life span in the oviduct of laying hens.

Expression of Immune Regulatory Genes in the Porcine Internal Genital Tract Is Differentially Triggered by Spermatozoa and Seminal Plasma

Mating or cervical deposition of spermatozoa or seminal plasma (SP) modifies the expression of genes affecting local immune defense processes at the oviductal sperm reservoir in animals with internal fertilization, frequently by down-regulation. Such responses may occur alongside sperm transport to or even beyond the reservoir. Here, immune-related gene expression was explored with cDNA microarrays on porcine cervix-to-infundibulum tissues, pre-/peri-ovulation. Samples were collected 24 h post-mating or cervical deposition of sperm-peak spermatozoa or SP (from the sperm-peak fraction or the whole ejaculate). All treatments of this interventional study affected gene expression. The concerted action of spermatozoa and SP down-regulated chemokine and cytokine (P00031), interferon-gamma signaling (P00035), and JAK/STAT (P00038) pathways in segments up to the sperm reservoir (utero-tubal junction (UTJ)/isthmus). Spermatozoa in the vanguard sperm-peak fraction (P1-AI), uniquely displayed an up-regulatory effect on these pathways in the ampulla and infundibulum. Sperm-free SP, on the other hand, did not lead to major effects on gene expression, despite the clinical notion that SP mitigates reactivity by the female immune system after mating or artificial insemination.

A new DNA marker of the TMIGD1 gene used to identify high fertilization rates in Tsaiya ducks (Anas platyrhynchos)

In a prior study, comparisons of individuals of Anas platyrhynchos with higher/lower reproductive performances showed that the expression of the transmembrane and immunoglobulin domain containing 1 (TMIGD1) gene significantly differed between the two groups. Here, we demonstrate that ducks with the TMIGD1 GG genotype have a significantly higher fertilization rate than other TMIGD1 genotypes. Primers designed based on the TMIGD1 sequence of Pekin duck were able to successfully amplify a TMIGD1 fragment from Tsaiya ducks, and sequencing results indicated that a single nucleotide polymorphism (SNP) of the TMIGD1 gene existed. We also developed a cost-effective method of restriction fragment length polymorphism. Using the above methods, ducks were classified into three genotypes. To identify the relationships between genotypes and traits, we recorded the ducks’ performance; to ensure the coverage of the entire duration of the fertile period, the egg collection period was extended to 18 days, and therefore, lower than usual fertilization rates were observed. Further assessment using a high-throughput system showed that the ducks with the GG genotype exhibited the highest fertilization rates among genotypes (P < 0.05). We suggest that TMIGD1 may affect the release of sperm protection factors from the female genital tract, and thus alter fertilization rate. In conclusion, the results of this study demonstrate that the TMIGD1 GG genotype can be used as a new DNA marker to identify animals with high fertilization rates at a young age, a process which could improve farming efficiency.

Expression of pro- and anti-inflammatory cytokines and chemokines during the ovulatory cycle and effects of aging on their expression in the uterine mucosa of laying hens

The aim of this study was to examine whether cytokines and chemokines expressed in the uterine mucosa play a role in the process of eggshell formation in the chicken uterus. Changes in the expression levels of pro- and anti-inflammatory cytokines and chemokines in the uterine mucosa during an ovulatory cycle (experiment 1) and effects of aging on their expression (experiment 2) were examined. In experiment 1, the expression of the pro-inflammatory cytokines IL1β, IL6, TNFSF15, and IFNγ, and a chemokine CX3CL1 was found to increase during eggshell biomineralization (16 h following oviposition), while anti-inflammatory TGFβ2 expression was found to increase at 4 h following oviposition. In experiment 2, a higher expression of the anti-inflammatory cytokines TGFβ2 and TGFβ3, and chemokines CXCLi2 and CX3CL1, was observed in aged hens than in young hens. A significantly higher number of macrophages and CD8+ T cells were observed in the uterine tissue of aged hens than in young hens. Furthermore, the expression of adhesion molecules associated with leukocytic infiltration was found to be higher in aged hens than in young hens. We conclude that the eggshell formation process may be affected by the pro- and anti-inflammatory cytokines and chemokines. The balanced expressions of these molecules might be disrupted in aged hens.

Transcriptome sequencing reveals key potential long non-coding RNAs related to duration of fertility trait in the uterovaginal junction of egg-laying hens

Duration of fertility, (DF) is an important functional trait in poultry production and lncRNAs have emerged as important regulators of various process including fertility. In this study we applied a genome-guided strategy to reconstruct the uterovaginal junction (UVJ) transcriptome of 14 egg-laying birds with long- and short-DF (n = 7); and sought to uncover key lncRNAs related to duration of fertility traits by RNA-sequencing technology. Examination of RNA-seq data revealed a total of 9977 lncRNAs including 2576 novel lncRNAs. Differential expression (DE) analysis of lncRNA identified 223 lncRNAs differentially expressed between the two groups. DE-lncRNA target genes prediction uncovered over 200 lncRNA target genes and functional enrichment tests predict a potential function of DE-lncRNAs. Gene ontology classification and pathway analysis revealed 8 DE-lncRNAs, with the majority of their target genes enriched in biological functions such as reproductive structure development, developmental process involved in reproduction, response to cytokine, carbohydrate binding, chromatin organization, and immune pathways. Differential expression of lncRNAs and target genes were confirmed by qPCR. Together, these results significantly expand the utility of the UVJ transcriptome and our analysis identification of key lncRNAs and their target genes regulating DF will form the baseline for understanding the molecular functions of lncRNAs regulating DF.

Letrozole, an aromatase inhibitor, reduces post-peak age-related regression of rooster reproductive performance

This study was designed to evaluate orally administrated Letrozole (Lz) on reproductive performance, plasma testosterone and estradiol concentrations and relative abundance of mRNA of GnRH, FSH and LH in roosters. Ross 308 roosters (n=32) that were 40-weeks of age were individually housed and received a basal standard diet supplemented different amounts of capsulated Lz [0 (Lz-0), 0.5 (Lz-0.5), 1 (Lz-1) or 1.5 (Lz-1.5), mg Lz/bird/day] for 12 weeks. Sperm quality variables and plasma testosterone and estradiol concentrations were assessed from the first to the tenth week of the treatment period. Semen samples from the 11th to 12th week were used for artificial insemination and eggs were collected and allotted to assess fertility and hatchability rates. Relative abundance of hypothalamic and pituitary GnRH, LH and FSH mRNA was evaluated at the end of 12th week. The results indicated that total and forward sperm motility as well as egg hatchability rate were greater in the Lz-0.5 group. Greater sperm concentrations, ejaculate volume, sperm plasma membrane integrity, testis index and fertility rates were recorded for both Lz-0.5 and Lz-1 groups compared with the Lz-0 group (P<0.05). Body weight, percentage of sperm abnormalities, and sperm plasma membrane functionality were not affected by treatment. Testosterone and estradiol concentrations were negatively related with greater testosterone concentrations in the Lz-1.5 group which had lesser estradiol concentrations. Relative mRNA transcript abundance for GnRH, LH and FSH was Lz dose responsive being greater in the treated groups; however, this trend plateaued for GnRH and for the relative abundance of both LH and FSH mRNA was less in the Lz-1.5 group than the other treatment groups. It is concluded that Lz may be an effective treatment to improve age related post-peak reproductive performance of roosters.

Novel copy number variation of the TGFβ3 gene is associated with TGFβ3 gene expression and duration of fertility traits in hens

Improvements in the duration of fertility (DF) could increase the interval between successive artificial inseminations, thereby decreasing the cost associated with production of hatching eggs. The molecular mechanisms involved in DF in hens remains under-explored. In this study, expression levels of the transforming growth factor-β genes (TGFβs: TGFβ1, TGFβ2, TGFβ3) were investigated in utero-vaginal junctions (UVJs) of hens with long DF (Group L, n = 10) and short DF (Group S, n = 10). TGFβ1 and 2 tended to exhibit higher expression levels in UVJs from Group L hens. The expression levels of TGFβ3 mRNA and protein were significantly increased in UVJs of hens from Group L compared to hens in Group S. Consistently, six TGFβs downstream genes (DAXX, MEKK1, T-BET, GATA-3, TAK1, and FOXP3) associated with the immune response were found to be significantly differentially expressed in UVJs of Group L than Group S hens. In addition, four SNPs were identified in intron 1 of TGFβ3, and these SNPs were significantly associated with DF traits (P < 0.05). Furthermore, we identified multi-copy and copy number variants (CNVs) in chicken TGFβ3 and later determined significant associations between TGFβ3 CNVs and DF traits in hens. Specifically, TGFβ3 copy number exhibited a significant positive correlation with its expression (P < 0.05). Collectively, our results suggest that chicken DF traits may be regulated by the expression of TGFβ3 in UVJ. Meanwhile, the copy number variation in the TGFβ3 gene identified in this study seems to be one marker for DF traits.

Conserved gene expression in sperm reservoirs between birds and mammals in response to mating

BACKGROUND

Spermatozoa are stored in the oviductal functional sperm reservoir in animals with internal fertilization, including zoologically distant classes such as pigs or poultry. They are held fertile in the reservoir for times ranging from a couple of days (in pigs), to several weeks (in chickens), before they are gradually released to fertilize the newly ovulated eggs. It is currently unknown whether females from these species share conserved mechanisms to tolerate such a lengthy presence of immunologically-foreign spermatozoa. Therefore, global gene expression was assessed using cDNA microarrays on tissue collected from the avian utero-vaginal junction (UVJ), and the porcine utero-tubal junction (UTJ) to determine expression changes after mating (entire semen deposition) or in vivo cloacal/cervical infusion of sperm-free seminal fluid (SF)/seminal plasma (SP).

RESULTS

In chickens, mating changed the expression of 303 genes and SF-infusion changed the expression of 931 genes, as compared to controls, with 68 genes being common to both treatments. In pigs, mating or SP-infusion changed the expressions of 1,722 and 1,148 genes, respectively, as compared to controls, while 592 genes were common to both treatments. The differentially expressed genes were significantly enriched for GO categories related to immune system functions (35.72-fold enrichment). The top 200 differentially expressed genes of each treatment in each animal class were analysed for gene ontology. In both pig and chicken, an excess of genes affecting local immune defence were activated, though frequently these were down-regulated. Similar genes were found in both the chicken and pig, either involved in pH-regulation (SLC16A2, SLC4A9, SLC13A1, SLC35F1, ATP8B3, ATP13A3) or immune-modulation (IFIT5, IFI16, MMP27, ADAMTS3, MMP3, MMP12).

CONCLUSION

Despite being phylogenetically distant, chicken and pig appear to share some gene functions for the preservation of viable spermatozoa in the female reservoirs.

Selection for higher fertility reflects in the seminal fluid proteome of modern domestic chicken

The high egg-laying capacity of the modern domestic chicken (i.e. White Leghorn, WL) has arisen from the low egg-laying ancestor Red Junglefowl (RJF) via continuous trait selection and breeding. To investigate whether this long-term selection impacted the seminal fluid (SF)-proteome, 2DE electrophoresis-based proteomic analyses and immunoassays were conducted to map SF-proteins/cytokines in RJF, WL and a 9th generation Advanced Intercross Line (AIL) of RJF/WL-L13, including individual SF (n=4, from each RJF, WL and AIL groups) and pools of the SF from 15 males of each group, analyzed by 2DE to determine their degree of intra-group (AIL, WL, and RJF) variability using Principal Component Analysis (PCA); respectively an inter-breed comparative analysis of intergroup fold change of specific SF protein spots intensity between breeds. The PCA clearly highlighted a clear intra-group similarity among individual roosters as well as a clear inter-group variability (e.g. between RJF, WL and AIL) validating the use of pools to minimize confounding individual variation. Protein expression varied considerably for processes related to sperm motility, nutrition, transport and survival in the female, including signaling towards immunomodulation. The major conserved SF-proteins were serum albumin and ovotransferrin. Aspartate aminotransferase, annexin A5, arginosuccinate synthase, glutathione S-transferase 2 and l-lactate dehydrogenase-A were RJF-specific. Glyceraldehyde-3-phosphate dehydrogenase appeared specific to the WL-SF while angiotensin-converting enzyme, γ-enolase, coagulation factor IX, fibrinogen α-chain, hemoglobin subunit α-D, lysozyme C, phosphoglycerate kinase, Src-substrate protein p85, tubulins and thioredoxin were AIL-specific. The RJF-SF contained fewer immune system process proteins and lower amounts of the anti-inflammatory/immunomodulatory TGF-β2 compared to WL and AIL, which had low levels- or lacked pro-inflammatory CXCL10 compared to RJF. The seminal fluid proteome differs between ancestor and modern chicken, with a clear enrichment of proteins and peptides related to immune-modulation for sperm survival in the female and fertility.

Effect of sperm concentration on characteristics and fertilization capacity of rooster sperm frozen in the presence of the antioxidants catalase and vitamin E

The objective of this study conducted was to determine the influence of different levels of sperm concentration, including catalase (CAT) and vitamin E (VitE) in rooster semen extender on postthawed quality and fertility of rooster semen. Semen was collected twice a week from six roosters (Arian) and diluted according to experimental treatments consisting of sperm suspensions containing different sperm concentrations (200, 400, and 600 × 106 sperm/mL) without antioxidant supplementation as control (Con) groups (Con200, Con400, and Con600, respectively), sperm suspensions containing different sperm concentrations (200, 400, and 600 × 106 sperm/mL) supplemented with 5-μg/mL VitE (VitE200, VitE400, and VitE600, respectively) and different sperm concentrations (200, 400, and 600 × 106 sperm/mL) supplementation with 100 IU/mL CAT (CAT200, CAT400, and CAT600, respectively). After thawing; sperm motility, membrane integrity, and mitochondrial function were assessed. Fertility and hatchability rates were determined by using 100 artificially inseminated hens. The percentage of total motility (TM) and activity of mitochondria decreased (P < 0.05) as the sperm concentration increased in control groups. So, the lowest percentage of the TM and activity of mitochondria were observed in the Con600 as compared with other treatment groups. Extenders containing 100 IU/mL CAT and 5-μg/mL VitE resulted in higher (P < 0.05) TM, progressive motility, membrane integrity, and activity of mitochondria compared with control groups. Adding VitE and CAT in different sperm concentrations, the percentage of TM, membrane integrity, and activity of mitochondria decreased (P < 0.05) as the sperm concentration decreased. The highest (P < 0.05) membrane integrity, TM, and progressive motility were recorded at VitE400 and CAT400. Including VitE and CAT in rooster extender with different level sperm concentrations had no effect (P > 0.05) on fertility and hatchability rates. In conclusion, although adding VitE and CAT in extender with different levels of sperm concentration improved postthawed quality of rooster semen, but adding VitE and CAT in the extender have no effect on fertility rate.

Is passive transmission of non-viral vectors through artificial insemination of sperm-DNA mixtures sufficient for chicken transgenesis?

DNA uptake in the post-acrosomal region of the spermatozoa takes place exclusively in immotile spermatozoa that are naturally unable to fertilize eggs. The present study aimed to assess whether passive transmission of non-viral vectors to the surrounding areas of chicken embryos could be an alternate mechanism in chicken sperm-mediated gene transfer. First, the presence of nucleases in rooster seminal plasma was evaluated. Semen ejaculates from five roosters were centrifuged and the supernatant was incubated with pBL2 for 1 h. A robust nuclease cocktail was detected in the rooster semen. To overcome these nucleases, plasmid-TransIT combinations were incubated with semen for 1 h. Incubation of exogenous DNA in the lipoplex structure could considerably bypass the semen nuclease effect. Then, intravaginal insemination of 1 × 10(9) sperm mixed with lipoplexes (40 µg pBL2:40 µl TransIT) was carried out in 15 virgin hens. Neither the epithelial tissue from the inseminated female reproductive tracts nor the produced embryos following artificial insemination showed the transgene. To remove any bias in the transgene transmission possibility, the plasmid-TransIT admixture was directly injected in close vicinity of the embryos in newly laid eggs. Nonetheless, none of the produced fetuses or chicks carried the transgene. In conclusion, the results of the present study revealed a nuclease admixture in rooster seminal plasma, and passive/active transmission of the non-viral vector into close vicinity of the chicken embryo was inefficient for producing transgenic chicks.

Lactic acid is a sperm motility inactivation factor in the sperm storage tubules

Although successful fertilization depends on timely encounters between sperm and egg, the decoupling of mating and fertilization often confers reproductive advantages to internally fertilizing animals. In several vertebrate groups, postcopulatory sperm viability is prolonged by storage in specialized organs within the female reproductive tract. In birds, ejaculated sperm can be stored in a quiescent state within oviductal sperm storage tubules (SSTs), thereby retaining fertilizability for up to 15 weeks at body temperature (41 °C); however, the mechanism by which motile sperm become quiescent within SSTs is unknown. Here, we show that low oxygen and high lactic acid concentrations are established in quail SSTs. Flagellar quiescence was induced by lactic acid in the concentration range found in SSTs through flagellar dynein ATPase inactivation following cytoplasmic acidification (<pH 6.0). The long-term preservation of sperm morphology under hypoxic and high temperature conditions indicates that a combination of these factors enables sperm cells to survive during the ovulation cycles. Our findings suggested a novel physiological role for lactic acid in promoting sperm quiescence in SSTs and opened up a new opportunity for technological improvement in prolonging sperm longevity at ambient or body temperature.

Sperm Storage in the Female Reproductive Tract

The capacity for sperm storage within the female reproductive tract occurs widely across all groups of vertebrate species and is exceptionally well developed in some reptiles (maximum duration seven years) and fishes (maximum duration >1 year). Although there are many reports on both the occurrence of female sperm storage in diverse species and its adaptive benefits, few studies have been directed toward explaining the mechanisms involved. In this article we review recent findings in birds and mammals in an effort to develop hypotheses that could be translated into research applications in animal breeding technologies. There are pockets of evidence to suggest that the local epithelial cells, sometimes arranged as sperm storage tubules, can respond to spermatozoa by producing heat shock proteins as well as providing an environment rich in antioxidants. Moreover, the local immune system seems to tolerate the arrival of spermatozoa, while retaining the ability to combat the arrival of infectious microorganisms.

Expression and localization of matrix metalloproteinases (MMP-2, -7, -9) and their tissue inhibitors (TIMP-2, -3) in the chicken oviduct during maturation

Although participation of matrix metalloproteinases (MMPs) in reproductive tract remodeling has been strongly suggested in mammalian species, the role of MMPs in the avian oviduct has received little attention. To gain a better understanding of the potential role of the MMP system in avian oviduct development, mRNA and protein expression, localization of selected MMPs and their tissue inhibitors (TIMPs), and gelatinolytic activity in the oviduct of growing chickens were examined. The oviducts were collected from Hy-Line Brown hens before (10, 12, 14 and 16 weeks of age) and after (week 17) the onset of egg laying. The MMP-2, -7, -9 and TIMP-2 and -3 genes were found to be differentially expressed in all examined oviductal sections: the infundibulum, magnum, isthmus and shell gland on both mRNA (by real time polymerase chain reaction) and protein (by western blotting and immunohistochemistry) levels. In the course of oviduct development, the relative expression of all genes decreased in most sections. Protein level of MMP-9 was diminished, while MMP-7 and TIMP-3 were elevated in the oviduct of growing birds. MMP-2 and TIMP-2 protein levels remained constant, with a slight increase in MMP-2 concentration just before reaching maturity. The relative activity of MMP-2 and -9 (assessed by gelatin zymography) was higher (P < 0.05, P < 0.01) in immature birds compared with adults. Immunohistochemistry demonstrated cell- and tissue-specific localization of MMPs and TIMPs in the wall of the chicken oviduct. We concluded that changes in the expression of examined MMPs and their inhibitors, as well as alterations in MMP activity occurring simultaneously with changes in the morphology of the chicken oviduct, suggest the involvement of the MMP system in the proper development and functioning of this organ. Mechanisms regulating the expression and activity of MMPs require further clarification.

Mating induces the expression of immune- and pH-regulatory genes in the utero-vaginal junction containing mucosal sperm-storage tubuli of hens

The female chicken, as with other species with internal fertilization, can tolerate the presence of spermatozoa within specialized sperm-storage tubuli (SST) located in the mucosa of the utero-vaginal junction (UVJ) for days or weeks, without eliciting an immune response. To determine if the oviduct alters its gene expression in response to sperm entry, segments from the oviduct (UVJ, uterus, isthmus, magnum and infundibulum) of mated and unmated (control) hens, derived from an advanced inter-cross line between Red Junglefowl and White Leghorn, were explored 24 h after mating using cDNA microarray analysis. Mating shifted the expression of fifteen genes in the UVJ (53.33% immune-modulatory and 20.00% pH-regulatory) and seven genes in the uterus, none of the genes in the latter segment overlapping the former (with the differentially expressed genes themselves being less related to immune-modulatory function). The other oviductal segments did not show any significant changes. These findings suggest sperm deposition causes a shift in expression in the UVJ (containing mucosal SST) and the uterus for genes involved in immune-modulatory and pH-regulatory functions, both relevant for sperm survival in the hen's oviduct.

A unique mechanism of successful fertilization in a domestic bird

Fertilization is an indispensable step for formation of a zygote in sexual reproduction, leading to species survival. When mating occurs, sperm is transported to the female reproductive tracts via the seminal plasma (SP). SP is derived from male accessory sex glands and it plays pivotal roles for fertilization in animals. However, molecular mechanisms of SP or a fluid derived from male accessory sex glands for successful fertilization remain unclear. Here, we report that in male quail the cloacal gland (CG) produces prostaglandin F_2α (PGF_2α) that contributes to successful fertilization. PGF_2α, as well as the secretion of CG (CGS), induced vaginal contractions and caused the opening of the entrance of the sperm storage tubules, the structures responsible for the long-term sperm storage and fertilization. The removal of CGS from the male before mating reduced the fertility, but the supplementation of CGS or PGF_2α rescued the subfertility. We further showed that male CG contains glucose that is utilized as energy source for the intrinsic sperm mobility after transportation to female vagina. This mechanism, in concert with the excitatory effects of PGF_2α enables successful fertilization in the domestic bird.

Reproductive performance and oviductal expression of avidin and avidin-related protein-2 in young and old broiler breeder hens orally exposed to supplementary biotin

Published data on the probable involvement of avidin and avidin-related protein-2 (AVR2) in sustaining sperm viability in sperm storage tubules in 38-wk-old turkeys, and the high affinity of avidin or its analogs to biotin suggest that supplementary biotin may increase oviductal avidin and AVR2 expression, thereby attenuating the adverse effect of aging on hen reproductive performance. Broiler breeder hens (n = 120) were randomly assigned to receive 0 (T0), 0.30 (T1), or 0.45 (T2) mg of biotin/L of drinking water from 30 to 33 (young) and 53 to 56 (old) wk of age, and artificially inseminated to determine their reproductive performance. At the end of each period of biotin administration, 8 hens from each treatment group were killed for RNA extraction from the uterovaginal junction. Egg production was lower in the old hens (44%) compared with the young ones (82%), and biotin supplementation increased egg production only in the latter. Administering supplementary biotin to young hens increased their oviductal expression of AVR2, which was much higher in the old hens (1.0 and 4.6 for young and old groups, respectively). Fertility rate was not different between young and old hens, and was increased (4.4%) at the higher level of biotin supplementation. Hatchability and hatchling quality were not affected by biotin supplementation. Embryonic mortality between 17 to 21 d of incubation was higher in young (5.2%) compared with old (1.4%) birds. Egg fertility rate showed a moderate correlation (P < 0.05) with avidin (r = 0.59) and AVR2 (r = 0.55) expression in the young-age group, and very low correlations in old-age group (0.04 and 0.17). Regardless of the hen's age, the correlation coefficient of hatchability with avidin or AVR2 expression was very low (-0.16 and 0.18). Overall, the effect of biotin supplementation on AVR2 expression, and the relationship between biotin administration and oviductal expression of avidin and AVR2 was dependent on the hen's age, being higher in the young hens.

Sperm storage in the female reproductive tract in birds

The ability to store sperm in the female genital tract is frequently observed in vertebrates as well as in invertebrates. Because of the presence of a system that maintains the ejaculated sperm alive in the female reproductive tract in a variety of animals, this strategy appears to be advantageous for animal reproduction. Although the occurrence and physiological reasons for sperm storage have been reported extensively in many species, the mechanism of sperm storage in the female reproductive tract has been poorly understood until recently. In avian species, the specialized simple tubular invaginations referred to as sperm storage tubules (SSTs) are found in the oviduct as a sperm storage organ. In this review, we summarize the current understanding of the mechanism of sperm uptake into the SSTs, maintenance within it, and controlled release of the sperm from the SSTs. Since sperm storage in avian species occurs at high body temperatures (i.e., 41 C), elucidation of the mechanism for sperm storage may lead to the development of new strategies for sperm preservation at ambient temperatures, and these could be used in a myriad of applications in the field of reproduction.

Sperm activation by heat shock protein 70 supports the migration of sperm released from sperm storage tubules in Japanese quail (Coturnix japonica)

Systems for maintaining the viability of ejaculated sperm in the female reproductive tract are widespread among vertebrates and invertebrates. In birds, this sperm storage function is performed by specialized simple tubular invaginations called sperm storage tubules (SSTs) in the uterovaginal junction (UVJ) of the oviduct. Although the incidence and physiological reasons for sperm storage in birds have been reported extensively, the mechanisms of sperm uptake by the SSTs, sperm maintenance within the SSTs, and control of sperm release from the SSTs are poorly understood. In this study, we demonstrated that the highly conserved heat shock protein 70 (HSP70) stimulates sperm motility in vitro and also that HSP70 expressed in the UVJ may facilitate the migration of sperm released from the SSTs. Quantitative RT-PCR analysis demonstrated that the expression of HSP70 mRNA in the UVJ increases before ovulation/oviposition. Gene-specific in situ hybridization and immunohistochemical analysis with a specific antibody to HSP70 demonstrated that HSP70 is localized in the surface epithelium of the UVJ. Furthermore, injection of anti-HSP70 antibody into the vagina significantly inhibited fertilization in vivo. In addition, we found that recombinant HSP70 activates flagellar movement in the sperm and that the binding of recombinant HSP70 to the sperm surface is mediated through an interaction with voltage-dependent anion channel protein 2 (VDAC2). Our results suggest that HSP70 binds to the sperm surface by interacting with VDAC2 and activating sperm motility. This binding appears to play an important role in sperm migration within the oviduct.

Mechanisms of sperm storage in the female reproductive tract: an interspecies comparison

Once semen has been collected for artificial insemination, it is diluted into extenders designed to prevent its deterioration over the period prior to insemination. If the semen is not frozen, the extenders provide protection for a period of a few hours to a few days, depending on species. Despite the efforts of biotechnologists to increase the duration of storage without compromising fertility, there has been relatively little progress for many years. However, comparative studies in diverse species have revealed that long-term sperm storage (up to months and years) within the female reproductive tract is relatively commonplace in reptiles, fishes, birds and amphibians. Even among mammals, some species of bat have evolved mechanisms for storing spermatozoa for several months in the uterus or oviduct so that they can mate in the autumn but postpone fertilization until the spring. We currently know little about the mechanisms that support such long-term sperm storage, mainly because evidence from such species is either absent or fragmentary. Nevertheless, parallels between mammalian and other systems, where spermatozoa are sequestered in sperm storage tubules, suggest that the enclosure of spermatozoa within pockets of epithelial cells may be sufficient to achieve long-term sperm storage. In addition, recent evidence from sperm-storing bats has suggested an alternative, or additional, hypothesis that the modulation of apoptosis within epithelial cells is important in controlling sperm survival. Despite a lack of direct experimental evidence from a wide variety of species, I propose that there is now enough evidence to warrant investigation of these hypotheses.

Oviductal expression of avidin, avidin-related protein-2, and progesterone receptor in turkey hens in relation to sperm storage: effects of oviduct tissue type, sperm presence, and turkey line

The sperm storage tubules (SST) of the turkey hen, which are located in the uterovaginal junction (UVJ) of the oviduct, maintain viable sperm for up to 10 wk after a single insemination. The mechanisms of this in vivo sperm storage are poorly understood. Our objective was to evaluate mRNA and protein expression of avidin and 2 avidin-associated factors, avidin-related protein-2 (AVR2) and progesterone receptor, in the oviducts of 2 different lines to determine the extent to which they were sperm responsive and tissue specific. At 38 wk of age, Hybrid Grade Maker and Converter turkey hens were artificially inseminated with diluted semen (AI) or were sham-inseminated with extender alone (SI). Forty-eight hours after insemination, total RNA was extracted from the UVJ epithelium (containing SST) and vaginal epithelium (VGE) of SI and AI hens. Real time-polymerase chain reaction data showed a clear tissue region-specific effect on gene expression in the turkey hen oviduct, with much greater (P < 0.0001) expression in the UVJ compared with VGE region for avidin and AVR2 mRNA in both lines and for progesterone receptor mRNA in the Converter line. In contrast to real-time PCR data, in situ hybridization of SI and AI tissues showed that the presence of sperm increased avidin mRNA in the SST and UVJ surface epithelium in the Converter hens. Immunohistochemistry confirmed the presence of avidin protein in the epithelium of the UVJ in both lines; however, whereas avidin protein was localized in the SST of SI-Grade Maker hens, this protein was not detected in the SST of Converter hens. The upregulation of avidin and AVR2 mRNA within the sperm storage region indicates the involvement of avidin, and perhaps avidin analogs, in the sustained storage of sperm in the SST, possibly through the binding of biotin to avidin. The absence of avidin protein in the SST and VGE of Converter hens in the presence of increased mRNA may indicate a rapid turnover of protein.

Expression of Toll-like receptors and avian β-defensins and their changes in response to bacterial components in chicken sperm

The aim of the present study was to examine whether chicken sperm express mRNA of Toll-like receptors (TLR) and avian β-defensins (avBD), and whether the expression of avBD in the sperm are regulated by the interaction of TLR-2 and TLR-4 with their corresponding ligands. Total RNA was extracted from fresh sperm and mRNA expression for TLR and avBD were examined by reverse-transcription PCR. Changes in the expression of avBD-5, avBD-9, avBD-10, and avBD-12 in the sperm after incubation with lipopolysaccharide (LPS; TLR-4 ligand) or lipopeptide (Pam3CSK4; TLR-2 ligand) were examined by real-time PCR. Among 8 types of TLR, PCR products of 7 types, namely, TLR-2 to TLR-5, TLR-7, TLR-15, and TLR-21, were identified in the sperm. The sperm also expressed cluster of differentiation 14 (CD14), which is required for the binding of LPS to TLR-4. Out of 14 avBD types reported in the chicken, a total of 9 types, namely, avBD-1, avBD-3, avBD-5, and avBD-7 to avBD-12 were expressed by the sperm, whereas avBD-5, avBD-9, avBD-10, and avBD-12 showed dense signals on the gel. Expression levels of avBD-5, avBD-9, avBD-10, and avBD-12 were significantly increased in the sperm stimulated with LPS, and that of avBD-5 was also enhanced by Pam3CSK4. These results suggest that avian sperm have the ability of the innate host defense to protect themselves from infection in the male and female genital tracts.

Molecular evolutionary analysis of seminal receptacle sperm storage organ genes of Drosophila melanogaster

Sperm storage organs are common and broadly distributed among animal taxa. However, little is known about how these organs function at the molecular level. Additionally, there is a paucity of knowledge about the evolution of genes expressed in these organs. This investigation is an evolutionary expressed sequence tag (EST) study of genes expressed in the seminal receptacle, one of the sperm storage organs in Drosophila. The incidence of positive selection is higher for the seminal receptacle genes than Drosophila reproductive genes as a whole, but lower than genes associated with the spermatheca, a second type of Drosophila sperm storage organ. By identifying overrepresented classes of proteins and classes for which sperm storage function is suggested by the nature of the proteins, candidate genes were discovered. These candidates belong to protein classes such as muscle contraction, odorant binding and odorant receptor, protease inhibitor and immunity.