CD9 protects the sperm from cytotoxic factors in the epididymis as extracellular components

The mechanism by which seemingly normal sperm cause infertility is still under debate. Although CD9 is expressed in male reproductive tissues, its role in male fertility remains unclear. To address this, we investigated the role of CD9 in analyzing Cd9 -deficient ( Cd9 -KO) male mice. The litter size of Cd9 -KO males was comparable, regardless of mating experience. When Cd9 -KO males experienced their first mating chance, a considerable number of neonates died 48 hours after birth. Electron microscopy reveals the presence of CD9 in the epididymal space. Our results suggest that CD9 contributes to male fertility as an extracellular component.

Identification of a syncytin gene in a non-rodent laboratory mammal, Suncus murinus

An endogenous retrovirus-derived membrane protein, syncytin (SYN), contributes to placental function via trophoblast fusion. Multinuclear trophoblasts (syncytiotrophoblasts) physically and functionally mediate the interaction between fetal and maternal vessels in various ways. Suncus murinus (suncus) is a small mammalian species with a pregnancy duration of approximately 30 days, 1.5 times longer than mice. However, the molecular basis for the longer pregnancy duration is unknown. In this study, we first isolated two genes that encoded putative SYN proteins expressed in the suncus placenta, which were named syncytin-1-like proteins 1 and 2 (SYN1L1 and SYN1L2). When their expression vectors were introduced into cultured cells, suncus SYN1L2 was found to be active in cell fusion. Moreover, the SYN1L2 protein was homologous to a SYN1-like protein identified in greater mouse-eared bats (bat SYN1L) and was structurally compared with bat SYN1L and other SYN proteins, implying the presence of structural features of the SYN1L2 protein.

Long days restore regular estrous cyclicity in mice lacking circadian rhythms

Many female mammals have recurring cycles of ovulation and sexual behaviors that are regulated by reproductive hormones and confer reproductive success. In addition to sexual behaviors, circadian behavioral rhythms of locomotor activity also fluctuate across the estrous cycle in rodents. Moreover, there is a bidirectional relationship between circadian rhythms and estrous cyclicity since mice with disrupted circadian rhythms also have compromised estrous cycles resulting in fewer pregnancies. In the present study, we assessed whether extending day length, which alters circadian rhythms, normalizes estrous cyclicity in mice. We found that Period (Per) 1/2/3 triple knockout (KO) mice, that have disabled canonical molecular circadian clocks, have markedly disrupted estrous cycles. Surprisingly, extending the day length by only 2 h per day restored regular 4- or 5-day estrous cycles to Per1/2/3 KO mice. Longer days also induced consistent 4-day, rather than 5-day, estrous cycles in wild-type C57BL/6J mice. These data demonstrate that extending daytime light exposure could be used for enhancing reproductive success.

Proteasome-Associated Proteins, PA200 and ECPAS, Are Essential for Murine Spermatogenesis

Proteasomes are highly sophisticated protease complexes that degrade non-lysosomal proteins, and their proper regulation ensures various biological functions such as spermatogenesis. The proteasome-associated proteins, PA200 and ECPAS, are predicted to function during spermatogenesis; however, male mice lacking each of these genes sustain fertility, raising the possibility that these proteins complement each other. To address this issue, we explored these possible roles during spermatogenesis by producing mice lacking these genes (double-knockout mice; dKO mice). Expression patterns and quantities were similar throughout spermatogenesis in the testes. In epididymal sperm, PA200 and ECPAS were expressed but were differentially localized to the midpiece and acrosome, respectively. Proteasome activity was considerably reduced in both the testes and epididymides of dKO male mice, resulting in infertility. Mass spectrometric analysis revealed LPIN1 as a target protein for PA200 and ECPAS, which was confirmed via immunoblotting and immunostaining. Furthermore, ultrastructural and microscopic analyses demonstrated that the dKO sperm displayed disorganization of the mitochondrial sheath. Our results indicate that PA200 and ECPAS work cooperatively during spermatogenesis and are essential for male fertility.

Sodium Hexametaphosphate Serves as an Inducer of Calcium Signaling

In bacteria, polymers of inorganic phosphates, particularly linear polyphosphate, are used as alternative phosphate donors for adenosine triphosphate production. A six-chain form of sodium metaphosphate, sodium hexametaphosphate (SHMP), is believed to have no physiological functions in mammalian cells. In this study, we explored the possible effects of SHMP on mammalian cells, using mouse oocytes, which are useful for observing various spatiotemporal intracellular changes. Fertilization-competent oocytes were isolated from the oviducts of superovulated mice and cultured in an SHMP-containing medium. In the absence of co-incubation with sperm, SHMP-treated oocytes frequently formed pronuclei and developed into two-cell embryos owing to the increase in calcium concentration in the cytoplasm. We discovered an intriguing role for SHMP as an initiator of calcium rise in mouse oocytes, presumably in a wide variety of mammalian cells.

Embryonic β-Catenin Is Required for Priming of the Uterus to Implantation

Repeated implantation failure is a major cause of infertility among healthy women. Uterine β-catenin (CTNNB1) plays a critical role in implantation. However, the role of embryonic CTNNB1 during implantation remains unclear. We addressed this topic by analyzing mice carrying Ctnnb1-deficient (Ctnnb1^Δ/Δ) embryos. Ctnnb1^Δ/Δ embryos were produced by intercrossing mice bearing Ctnnb1-deficient eggs and sperms. We found that Ctnnb1^Δ/Δ embryos developed to the blastocyst stage; thereafter, they were resorbed, leaving empty decidual capsules. Moreover, leukemia inhibitory factor, a uterine factor essential for implantation, was undetectable in Ctnnb1^Δ/Δ blastocysts. Furthermore, CDX2, a transcription factor that determines the fate of trophectoderm cells, was not observed in Ctnnb1^Δ/Δ blastocysts. Intrauterine injection with uterine fluids (from control mice) and recombinant mouse leukemia inhibitory factor proteins rescued the uterine response to Ctnnb1^Δ/Δ blastocysts. These results suggest that embryonic CTNNB1 is required for the secretion of blastocyst-derived factor(s) that open the implantation window, indicating that the uterine response to implantation can be induced using supplemental materials. Therefore, our results may contribute to the discovery of a similar mechanism in humans, leading to a better understanding of the pathogenesis of repeated implantation failure.

Extra-mitochondrial citrate synthase controls cAMP-dependent pathway during sperm acrosome reaction in mice

The sperm consumes adenosine triphosphate (ATP) to maintain the cellular function, viability, acrosome reaction (AR), and motility. Extra-mitochondrial citrate synthase (eCS) catalyzes citrate production in the sperm head, and thus regulates sperm function through ATP synthesis, similarly to CS. This study aimed to investigate how eCS regulates AR. Herein, acrosome-reacted (ARed) sperms were rarely detected on the zona pellucida, and spontaneous ARed sperm in eCs -deficient (KO) sperm remained at low levels even with induced capacitation. Retarded AR of eCs -KO sperm was enhanced by cyclic adenosine 3',5'-monophosphate (cAMP) treatment. In conclusion, eCS regulates AR via a cAMP-dependent pathway, which presumably contributes to sperm metabolism.

Regulatory role of CsuR (YiaU) in determination of cell surface properties of Escherichia coli K-12

Genomic SELEX screening was performed to identify the binding sites of YiaU, an uncharacterized LysR family transcription factor, on the Escherichia coli K-12 genome. Five high-affinity binding targets of YiaU were identified, all of which were involved in the structures of the bacterial cell surface such as outer and inner membrane proteins, and lipopolysaccharides. Detailed in vitro and in vivo analyses suggest that YiaU activates these target genes. To gain insight into the effects of YiaU in vivo on physiological properties, we used phenotype microarrays, biofilm screening assays and the sensitivity against serum complement analysed using a yiaU deletion mutant or YiaU expression strain. Together, these results suggest that the YiaU regulon confers resistance to some antibiotics, and increases biofilm formation and complement sensitivity. We propose renaming YiaU as CsuR (regulator of cell surface).

Suppressive Role of Lactoferrin in Overweight-Related Female Fertility Problems

The secretory glycoprotein lactoferrin (LF) is suggested to ameliorate overweight regardless of non-genetic or genetic mechanisms. Although maternal overweight represents a key predictor of offspring growth, the efficacy of LF on fertility problems in overweight and obese mothers remains unknown. To address this issue, we examined the effect of LF ingestion by analyzing overweight mice (Institute of Cancer Research (ICR) mice with high-fat diets; HF mice) and obese mice (leptin-deficient mice with type II diabetes; ob/ob mice). Plasma insulin, leptin, glucose, and cholesterol levels were measured, and thermal imaging and histological analysis were employed. The litter size of HF females was reduced due to miscarriage, which was reversed by LF ingestion. In addition, LF ingestion suppressed overweight prevalence in their offspring. The component analysis of the maternal blood demonstrated that glucose concentration in both HF females and their offspring was normalized by LF ingestion, which further standardized the concentration of insulin, but not leptin. LF ingestion was unable to reverse female infertility in ob/ob mice, although their obesity and uterine function were partially improved. Our results indicate that LF upregulates female fertility by reinforcing ovarian and uterine functions in females that are overweight due to caloric surplus.

Effects of tris(1,3-dichloro-2-propyl) phosphate on epididymal sperm parameters in adult male rats

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is widely used as a flame retardant and is known to exhibit anti-androgenic effects in vitro and in vivo. To assess the reproductive toxicity potency of TDCIPP, we investigated the effects of 7 days of TDCIPP oral administration on epididymal sperm motion and concentration in adult male Wistar-Imamichi rats. Thirty-five days after the final administration, sperm parameters were evaluated by computer-assisted sperm analysis. Results showed that sperm swimming progression and vigor and sperm concentration in TDCIPP-treated rats were unexpectedly higher than those in control rats. TDCIPP did not significantly affect the percentage of motile sperms or sperm swimming pattern. These results contribute to the understanding of the biological effects of TDCIPP.

Sperm acrosome status before and during fertilization in the Chinese hamster (Cricetulus griseus), and observation of oviductal vesicles and globules

The present study was conducted to determine exact location where the acrosome reaction of fertilizing spermatozoa begins in the oviduct of the Chinese hamster. Unlike spermatozoa of other rodent species, Chinese hamster spermatozoa did not spontaneously undergo the acrosome reaction in fertilization-supporting media. In naturally mated females, spermatozoa in the uterus had intact acrosomes, whereas those in the lower oviductal isthmus had visibly thin acrosomal caps. The acrosomal cap was lost when spermatozoa passed through the cumulus oophorus. Thus, Chinese hamster spermatozoa begin the acrosome reaction in the lower isthmus and complete it in the cumulus oophorus. The mucosal epithelium of the oviductal isthmus released many "transparent" vesicles into the lumen, was very fragile and readily sloughed off by rough handling or rapid flushing with medium. Globular materials that oozed out of the dissected oviduct were most likely mucosa cells destroyed by rough handling. Although the oviducts of Chinese hamsters may be exceptionally delicate, this observation nevertheless warns us to cautiously handle the oviducts of any species when studying oviduct secretions that could be involved in inducing capacitation and the acrosome reaction of spermatozoa within the female genital tract.

Identification of an antibacterial polypeptide in mouse seminal vesicle secretions

In both men and women, pathogenic bacteria enter the reproductive tract and cause harmful symptoms. Intrauterine and oviductal inflammation after copulation may have severe effects, such as infertility, implantation failure, oviduct obstruction, and robust life-threatening bacterial infection. Human seminal plasma is considered to be protective against bacterial infection. Among its components, Semenogelin-I/-II proteins are digested to function as bactericidal factors; however, their sequences are not conserved in mammals. Therefore, alternative antibacterial (bactericidal and/or bacteriostatic) systems may exist across mammals. In this study, we examined the antibacterial activity in the seminal plasma of mice lacking a gene cluster encoding Semenogelin-I/-II counterparts. Even in the absence of the majority of seminal proteins, antibacterial activity remained in the seminal plasma. Moreover, a combination of gel chromatography and liquid chromatography coupled with tandem mass spectrometry revealed that the prostate and testis expressed 4 protein as a novel antibacterial (specifically, bacteriostatic) protein, the sequence of which is broadly conserved across mammals. Our results provide the first evidence of a bacteriostatic protein that is widely present in the mammalian seminal plasma.

Similar responsiveness between C57BL/6N and C57BL/6J mouse substrains to superovulation

Superovulation is a method for the drug-induced release of multiple eggs and useful for in vitro fertilization. Thus, its high efficiency largely reduces the number of mice used per experiment. We compared the responsivity to superovulation between C57BL/6N (B6N) and C57BL/6J (B6J) substrains. The average number of ovulated eggs was strikingly higher in both substrains treated with anti-inhibin serum (AIS) plus equine chorionic gonadotropin (eCG) than those treated with eCG alone. Our data indicate that hypothalamus-pituitary-ovarian axis similarly responds to eCG treatment in B6N and B6J mice, and that this responsiveness is enhanced by the presence of AIS.

Human Semenogelin 1 Promotes Sperm Survival in the Mouse Female Reproductive Tract

Semenogelin 1 (SEMG1), a main component of human seminal plasma, is a multi-functional protein involved in the regulation of sperm motility and fertility. SEMG1 is orthologous to mouse seminal vesicle secretion 2 (SVS2), required for sperm survival in the female reproductive tract after copulation; however, its in vivo function remains unclear. In this study, we addressed this issue by examining the effect of recombinant SEMG1 on intrauterine mouse sperm survival. SEMG1 caused a dose-dependent decrease in mouse sperm motility, similar to its effect on human sperm, but SVS2 had no effect on mouse sperm motility. Mouse epididymal sperm in the presence of 100 µM SEMG1, a concentration that does not affect mouse sperm motility, were injected into the mouse uterus (intrauterine insemination, IUI). IUI combined with SEMG1 significantly increased the survival rate of intrauterine mouse sperm. The effect of SEMG1 on intrauterine sperm survival was comparable with that of SVS2. For clinical applications, three potentially sperm-protecting polypeptides that are easy to handle were designed from SEMG1, but their individual use was unable to mimic the ability of SEMG1. Our results indicate that SEMG1 has potential clinical applications for effective IUI and thereby for safe, simple, and effective internal fertilization.

Correction: Extra-mitochondrial citrate synthase initiates calcium oscillation and suppresses age-dependent sperm dysfunction

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Creation of CRISPR-based germline-genome-engineered mice without ex vivo handling of zygotes by i-GONAD

Methods to create genetically engineered mice involve three major steps: harvesting embryos from one set of females, microinjection of reagents into embryos ex vivo and their surgical transfer to another set of females. Although tedious, these methods have been used for more than three decades to create mouse models. We recently developed a method named GONAD (genome editing via oviductal nucleic acids delivery), which bypasses these steps. GONAD involves injection of CRISPR components (Cas9 mRNA and guide RNA (gRNA)) into the oviducts of pregnant females 1.5 d post conception, followed by in vivo electroporation to deliver the components into the zygotes in situ. Using GONAD, we demonstrated that target genes can be disrupted and analyzed at different stages of mouse embryonic development. Subsequently, we developed improved GONAD (i-GONAD) by delivering CRISPR ribonucleoproteins (RNPs; Cas9 protein or Cpf1 protein and gRNA) into day-0.7 pregnant mice, which made it suitable for routine generation of knockout and large-deletion mouse models. i-GONAD can also generate knock-in models containing up to 1-kb inserts when single-stranded DNA (ssDNA) repair templates are supplied. i-GONAD offers other advantages: it does not require vasectomized males and pseudo-pregnant females, the females used for i-GONAD are not sacrificed and can be used for other experiments, it can be easily adopted in laboratories lacking sophisticated microinjection equipment, and can be implemented by researchers skilled in small-animal surgery but lacking embryo-handling skills. Here, we provide a step-by-step protocol for establishing the i-GONAD method. The protocol takes ∼6 weeks to generate the founder mice.

Calaxin is required for cilia-driven determination of vertebrate laterality

Calaxin is a Ca2+-binding dynein-associated protein that regulates flagellar and ciliary movement. In ascidians, calaxin plays essential roles in chemotaxis of sperm. However, nothing has been known for the function of calaxin in vertebrates. Here we show that the mice with a null mutation in Efcab1, which encodes calaxin, display typical phenotypes of primary ciliary dyskinesia, including hydrocephalus, situs inversus, and abnormal motility of trachea cilia and sperm flagella. Strikingly, both males and females are viable and fertile, indicating that calaxin is not essential for fertilization in mice. The 9 + 2 axonemal structures of epithelial multicilia and sperm flagella are normal, but the formation of 9 + 0 nodal cilia is significantly disrupted. Knockout of calaxin in zebrafish also causes situs inversus due to the irregular ciliary beating of Kupffer's vesicle cilia, although the 9 + 2 axonemal structure appears to remain normal.

Membrane protein CD9 is repositioned and released to enhance uterine function

Tetraspanin CD9 is essential for sperm-egg fusion and also contributes to uterine repair through microexosome formation. Microexosomes share CD9 with exosomes and are released from eggs and uterine epithelial cells. However, the mechanism for the formation of microexosomes remains unknown. To address this issue, we examined membrane localization and extracellular release of CD9 proteins using uterine epithelial cells and secretions in mice and humans. In mice, CD9 localized predominantly on the basal region of the plasma membrane and relocated to the apical region upon embryo implantation. Furthermore, extracellular CD9 proteins were detected in uterine secretions of mice and women undergoing infertility treatment, but were below detectable levels in supernatants of pluripotent stem cells. Ultrastructural analysis demonstrated that membrane projections were shortened and the number of mitochondria was reduced in uterine epithelial cells lacking Cd9 genes. Our results suggest that CD9 repositioning and release affect both membrane structures and mitochondrial state in the uterus, and contribute to female fertility.

Chemotactic behavior of egg mitochondria in response to sperm fusion in mice

Mitochondria are the powerhouses of eukaryotic cells and their positioning contributes to fertilization and early developmental processes. We report that sperm fusion triggers Ca²⁺ oscillations and mitochondrial movement toward fused sperm (mitochondrial chemotaxis) in mouse eggs. Mitochondria functioned in Ca²⁺ storage and were colocalized with endoplasmic reticulum (ER) during Ca²⁺ oscillations. Mitochondria then moved toward the fused sperm. Sperm extracts lacking nuclei induced Ca²⁺ oscillations, but did not promote mitochondrial chemotaxis. Our results suggest that sperm fusion motivates Ca²⁺ oscillation-independent mitochondrial chemotaxis. This phenomenon indicates that egg mitochondria interact with sperm materials, presumably nuclear substances, and their network tethers egg and sperm nuclei at the early stage of zygote formation.

Degradation of phosphate polymer polyP enhances lactic fermentation in mice

In bacteria, a polymer of inorganic phosphate (Pi) (inorganic polyphosphate; polyP) is enzymatically produced and consumed as an alternative phosphate donor for adenosine triphosphate (ATP) production to protect against nutrient starvation. In vertebrates, polyP has been dismissed as a "molecular fossil" due to the lack of any known physiological function. Here, we have explored its possible role by producing transgenic (TG) mice widely expressing Saccharomyces cerevisiae exopolyphosphatase 1 (ScPPX1), which catalyzes hydrolytic polyP degradation. TG mice were produced and displayed reduced mitochondrial respiration in muscles. In female TG mice, the blood concentration of lactic acid was enhanced, whereas ATP storage in liver and brain tissues was reduced significantly. Thus, we suggested that the elongation of polyP reduces the intracellular Pi concentration, suppresses anaerobic lactic acid production, and sustains mitochondrial respiration. Our results provide an insight into the physiological role of polyP in mammals, particularly in females.

Autophagy-disrupted LC3 abundance leads to death of supporting cells of human oocytes

Autophagic recycling of cell parts is generally termed as the opposite of cell death. Here, we explored the relation between cell death and autophagy by examining granulosa cell layers that control oocyte quality, which is important for the success of fertilization. Granulosa cell layers were collected from infertile women and morphologically divided into four types, viz., mature (MCCs), immature (ICCs), and dysmature cumulus cells (DCCs), and mural granulosa cells (MGCs). Microtubule-associated protein light chain 3 (LC3), which is involved in autophagosome formation, was expressed excessively in DCCs and MGCs, and their chromosomal DNA was highly fragmented. However, autophagy initiation was limited to MGCs, as indicated by the expression of membrane-bound LC3-II and autophagy-related protein 7 (ATG7), an enzyme that converts LC3-I to LC3-II. Although pro-LC3 was accumulated, autophagy was disabled in DCCs, resulting in cell death. Our results suggest the possibility that autophagy-independent accumulation of pro-LC3 proteins leads to the death of human granulosa cells surrounding the oocytes and presumably reduces oocyte quality and female fertility.

Ubiquitin-activating enzyme E1 inhibitor PYR-41 retards sperm enlargement after fusion to the egg

The ubiquitin-proteasome system, which is initiated by a single ubiquitin-activating enzyme E1 (UBE1), is involved in male reproduction via spermatogenesis and function in mammals. Here we explored the influence of UBE1-specific inhibitor, 4[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoic acid ethyl ester (pyrazone-41 or PYR-41) in female reproduction. UBE-1 was detected by immunoblotting and immunocytochemistry in mouse eggs and was localized mainly under the egg plasma membrane. PYR-41 pretreatment suppresses the development of eggs into two-cell embryos. Specifically, pretreatment retarded sperm enlargement and meiotic chromosomal division after sperm-egg fusion. PYR-41 pretreatment disturbed β-catenin, a well-known target protein for ubiquitination, localization under the egg plasma membrane and on spindle microtubules in wild-type eggs. Otherwise, PYR-41 treatment had no effect on the two-cell development of eggs lacking β-catenin. Our results raise the possibility that inhibition of the ubiquitin-proteasome system suppresses sperm enlargement through impaired β-catenin-mediated mechanism.

Birthweights and Down syndrome in neonates that were delivered after frozen-thawed embryo transfer: The 2007-2012 Japan Society of Obstetrics and Gynecology National Registry data in Japan

Aim

To evaluate the use of frozen embryos on the outcome of assisted reproductive technology (ART), a retrospective study of the Japanese Assisted Reproductive Technology Registry data during the years 2007‐2012 was conducted.

Methods

A total of 124 946 singleton neonates who reached term gestation following ART from 2007‐2012, with 80 660 achieved through frozen‐thawed embryo transfer (ET) and 44 286 being achieved through fresh ET, were analyzed for their birthweights and chromosomal abnormalities.

Results

The birthweight of the neonates from the frozen‐thawed ETs was significantly higher than that of those from the fresh ETs throughout all the study years. The frequency of Down syndrome was 0.17% for the fresh ETs and 0.13% for the frozen‐thawed ETs in the period 2007‐2012. This study showed that frozen‐thawed ETs result in a constant increase of the average birthweight between 37 and 41 weeks gestational age and lower frequencies of Down syndrome.

Conclusion

Frozen‐thawed ETs were comparable to the fresh ET method, with the exceptions of higher birthweights and a lower frequency of Down syndrome in the neonates that were born from frozen‐thawed ET. The increase in birthweights was not proportional to the gestational ages. This cannot be explained with any well‐known mechanism. The frequency of chromosomal abnormalities needs detailed data for analysis.

Exosomes versus microexosomes: Shared components but distinct functions

In multicellular organisms, cellular components are constantly translocated within cells and are also transported exclusively between limited cells, regardless of their physical distance. Exosomes function as one of the key mediators of intercellular transportation. External vesicles were identified 50 years ago in plants and now reconsidered to be exosome-like vesicles. Meanwhile, a well-known exosomal component, tetraspanin CD9, regulates sperm-egg fusion in mammals. A number of Arabidopsis tetraspanins are also expressed in reproductive tissues at fertilization, and are localized at the plasma membrane of protoplasts. Moreover, CD9-containing structures (or 'microexosomes') are released from mouse eggs during their maturation and promote the sperm-egg fusion. This phenomenon implies that two types of shared-component intercellular carriers might be released from multiple types of plant and animal cells, which widely regulate biological phenomena. We herein highlight their discrete structures, formation processes, and functions.

Evaluation of the safety and efficacy of Glycyrrhiza uralensis root extracts produced using artificial hydroponic and artificial hydroponic-field hybrid cultivation systems

Glycyrrhiza uralensis roots used in this study were produced using novel cultivation systems, including artificial hydroponics and artificial hydroponic-field hybrid cultivation. The equivalency between G. uralensis root extracts produced by hydroponics and/or hybrid cultivation and a commercial Glycyrrhiza crude drug were evaluated for both safety and efficacy, and there were no significant differences in terms of mutagenicity on the Ames tests. The levels of cadmium and mercury in both hydroponic roots and crude drugs were less than the limit of quantitation. Arsenic levels were lower in all hydroponic roots than in the crude drug, whereas mean lead levels in the crude drug were not significantly different from those in the hydroponically cultivated G. uralensis roots. Both hydroponic and hybrid-cultivated root extracts showed antiallergic activities against contact hypersensitivity that were similar to those of the crude drug extracts. These study results suggest that hydroponic and hybrid-cultivated roots are equivalent in safety and efficacy to those of commercial crude drugs. Further studies are necessary before the roots are applicable as replacements for the currently available commercial crude drugs produced from wild plant resources.

Seminal vesicle proteins SVS3 and SVS4 facilitate SVS2 effect on sperm capacitation

Mammalian spermatozoa acquire their fertilizing ability in the female reproductive tract (sperm capacitation). On the other hand, seminal vesicle secretion, which is a major component of seminal plasma, inhibits the initiation of sperm capacitation (capacitation inhibition) and reduces the fertility of the capacitated spermatozoa (decapacitation). There are seven major proteins involved in murine seminal vesicle secretion (SVS1-7), and we have previously shown that SVS2 acts as both a capacitation inhibitor and a decapacitation factor, and is indispensable for in vivo fertilization. However, the effects of SVSs other than SVS2 on the sperm have not been elucidated. Since mouse Svs2-Svs6 genes evolved by gene duplication belong to the same gene family, it is possible that SVSs other than SVS2 also have some effects on sperm capacitation. In this study, we examined the effects of SVS3 and SVS4 on sperm capacitation. Our results showed that both SVS3 and SVS4 are able to bind to spermatozoa, but SVS3 alone showed no effects on sperm capacitation. On the other hand, SVS4 acted as a capacitation inhibitor, although it did not show decapacitation abilities. Interestingly, SVS3 showed an affinity for SVS2 and it facilitated the effects of SVS2. Interaction of SVS2 and spermatozoa is mediated by the ganglioside GM1 in the sperm membrane; however, both SVS3 and SVS4 had weaker affinities for GM1 than SVS2. Therefore, we suggest that separate processes may cause capacitation inhibition and decapacitation, and SVS3 and SVS4 act on sperm capacitation cooperatively with SVS2.

Breast milk stimulates growth hormone secretion in infant mice, and phosphorus insufficiency disables this ability and causes dwarfism-like symptoms

INTRODUCTION

Breast milk intake facilitates neonatal growth, and its effect is assumed to last long into the adulthood. We recently reported that dietary phosphorus insufficiency reduces the ability of breast milk to promote infant growth in mice. However, how phosphorus confers this ability to milk is still unclear.

METHODS

To address this issue, we performed biochemical and physiological comparisons of milk secreted from C57BL/6J mice fed a low-phosphorus diet (LPD) or a normal-phosphorus control diet.

RESULTS

Although serum phosphorus concentration was decreased, the body weight of mother mice was unaffected. By contrast, infant body weight was significantly reduced, and dwarfism-like symptoms were observed in adulthood. Quantitative analysis revealed that the serum concentration of growth hormone (GH) was substantially reduced, and concomitantly insulin-like growth factor 1 and fibroblast growth factor 23 were decreased. Immunohistochemical analysis revealed ectopic fat accumulation in the livers of infant mice along with increased blood cholesterol level. Moreover, electron microscopy indicated fragility of the outer membrane of milk droplets.

CONCLUSIONS

Our results suggest that phosphorus is essential for the formation of milk droplets, which function as a stimulator of growth factor secretion in infant offspring.

Staphylococcus epidermidis is involved in a mechanism for female reproduction in mice

Both external and internal surfaces of organs (e.g., skin, mouth, gut, and intestine) are covered with bacteria, which often contribute to physiological events in host animals. Despite externally opened organs, the presence of bacteria in the mammalian female reproductive tract is uncertain. Here we assessed this problem using wild-type strains of mice, C57BL/6N and ICR. We first demonstrated that bacterial colonies were formed from the oviductal fluid in the C57BL/6N mice with birth experience (“parous”), but not in the mice without birth experience (“non-parous”). Sequence analysis of 16S ribosomal RNA (rRNA) revealed that Staphylococcus epidermidis existed in the oviductal fluid of the parous mice, confirmed by immunohistochemical analysis. Furthermore, extinction of bacterial population with intraperitoneal injection of antibiotics, penicillin G and streptomycin, disturbed the regularly implanted pattern of embryos in ICR mice. Our results indicate that symbiotic S. epidermidis plays a role in interaction between embryo and uterus upon implantation in mice.

Seminal vesicle secretion 2 acts as a protectant of sperm sterols and prevents ectopic sperm capacitation in mice

Seminal vesicle secretion 2 (SVS2) is a protein secreted by the mouse seminal vesicle. We previously demonstrated that SVS2 regulates fertilization in mice; SVS2 is attached to a ganglioside GM1 on the plasma membrane of the sperm head and inhibits sperm capacitation in in vitro fertilization as a decapacitation factor. Furthermore, male mice lacking SVS2 display prominently reduced fertility in vivo, which indicates that SVS2 protects spermatozoa from some spermicidal attack in the uterus. In this study, we tried to investigate the mechanisms by which SVS2 controls in vivo sperm capacitation. SVS2-deficient males that mated with wild-type partners resulted in decreased cholesterol levels on ejaculated sperm in the uterine cavity. SVS2 prevented cholesterol efflux from the sperm plasma membrane and incorporated liberated cholesterol in the sperm plasma membrane, thereby reversibly preventing the induction of sperm capacitation by bovine serum albumin and methyl-beta-cyclodextrin in vitro. SVS2 enters the uterus and the uterotubal junction, arresting sperm capacitation in this area. Therefore, our results show that SVS2 keeps sterols on the sperm plasma membrane and plays a key role in unlocking sperm capacitation in vivo.

Epididymal C4b-binding protein is processed and degraded during transit through the duct and is not essential for fertility

C4b-binding protein (C4BP) is known as one of the circulating complement regulators that prevents excessive activation of the host-defense complement system. We have reported previously that C4BP is expressed abundantly in the rodent epididymis, one of the male reproductive organs connecting the testis and vas deferens, where immature spermatozoa acquire their motility and fertilizing ability during their transit through the duct. Epididymal C4BP (EpC4BP) is synthesized androgen-dependently by the epithelial cells, secreted into the lumen, and bound to the outer membrane of the passing spermatozoa. In this study, we found that EpC4BP is secreted as a large oligomer, similar to the serum C4BP, but is digested during the epididymal transit and is almost lost from both the luminal fluid and the sperm surface in the vas deferens. Such a processing pattern is not known in serum C4BP, suggesting that EpC4BP and serum C4BP might have different functional mechanisms, and that there is a novel function of EpC4BP in reproduction. In addition, the disappearance of EpC4BP from the sperm surface prior to ejaculation suggests that EpC4BP works only in the epididymis and would not work in the female reproductive tract to protect spermatozoa from complement attack. Next, we generated C4BP-deficient (C4BP-/-) mice to examine the possible role of EpC4BP in reproduction. However, the C4BP-/- mice were fertile and no significant differences were observed between the C4BP-/- and wild-type mouse spermatozoa in terms of morphology, motility, and rate of the spontaneous acrosome reaction. These results suggest that EpC4BP is involved in male reproduction, but not essential for sperm maturation.

Mitochondrial fission factor Drp1 maintains oocyte quality via dynamic rearrangement of multiple organelles

Mitochondria are dynamic organelles that change their morphology by active fusion and fission in response to cellular signaling and differentiation. The in vivo role of mitochondrial fission in mammals has been examined by using tissue-specific knockout (KO) mice of the mitochondria fission-regulating GTPase Drp1, as well as analyzing a human patient harboring a point mutation in Drp1, showing that Drp1 is essential for embryonic and neonatal development and neuronal function. During oocyte maturation and aging, structures of various membrane organelles including mitochondria and the endoplasmic reticulum (ER) are changed dynamically, and their organelle aggregation is related to germ cell formation and epigenetic regulation. However, the underlying molecular mechanisms of organelle dynamics during the development and aging of oocytes have not been well understood. Here, we analyzed oocyte-specific mitochondrial fission factor Drp1-deficient mice and found that mitochondrial fission is essential for follicular maturation and ovulation in an age-dependent manner. Mitochondria were highly aggregated with other organelles, such as the ER and secretory vesicles, in KO oocyte, which resulted in impaired Ca(2+) signaling, intercellular communication via secretion, and meiotic resumption. We further found that oocytes from aged mice displayed reduced Drp1-dependent mitochondrial fission and defective organelle morphogenesis, similar to Drp1 KO oocytes. On the basis of these findings, it appears that mitochondrial fission maintains the competency of oocytes via multiorganelle rearrangement.

CD81 and CD9 work independently as extracellular components upon fusion of sperm and oocyte

When a sperm and oocyte unite into one cell upon fertilization, membranous fusion between the sperm and oocyte occurs. In mice, Izumo1 and a tetraspanin molecule CD9 are required for sperm-oocyte fusion as one of the oocyte factors, and another tetraspanin molecule CD81 is also thought to involve in this process. Since these two tetraspanins often form a complex upon cell-cell interaction, it is probable that such a complex is also formed in sperm-oocyte interaction; however, this possibility is still under debate among researchers. Here we assessed this problem using mouse oocytes. Immunocytochemical analysis demonstrated that both CD9 and CD81 were widely distributed outside the oocyte cell membrane, but these molecules were separate, forming bilayers, confirmed by immunobiochemical analysis. Electron-microscopic analysis revealed the presence of CD9- or CD81-incorporated extracellular structures in those bilayers. Finally, microinjection of in vitro-synthesized RNA showed that CD9 reversed a fusion defect in CD81-deficient oocytes in addition to CD9-deficient oocytes, but CD81 failed in both oocytes. These results suggest that both CD9 and CD81 independently work upon sperm-oocyte fusion as extracellular components.

Prognostic value of Ki-67 (MIB-1) and p53 in ependymomas

To determine whether Ki-67 (MIB-1) and p53 have prognostic value in ependymomas, clinicopathologic study was undertaken in 29 patients with this tumor. The clinical course correlated well with the histological grade according to the World Health Organization (WHO) grading system, and it was the worst in patients with anaplastic ependymoma. The percent expression of MIB-1 and p53 correlated with the histological grade of malignancy. With regard to the subtypes of benign ependymoma, the clinical course was the worst in clear-cell ependymoma, which had a significantly higher expression of MIB-1 and p53 than the other subtypes. Tanycytic ependymoma showed the most benign clinical course and the lowest expression of MIB-1 and p53. Although the WHO grading generally tended to correlate with the clinical course of ependymomas, these two subtypes--clear-cell ependymoma and tanycytic ependymoma--exhibited biological properties different from those of other grade II ependymomas.

Innate immune system still works at diapause, a physiological state of dormancy in insects

Diapause is most often observed in insects and is a physiologically dormant state different from other types of dormancy, such as hibernation. It allows insects to survive in harsh environments or extend longevity. In general, larval, pupal, or adult non-diapausing insects possess an innate immune system preventing the invasion of microorganisms into their bodies; however, it is unclear whether this system works under the dormant condition of diapause. We here report the occurrence of innate cellular reactions during diapause using pupae of a giant silkmoth, Samia cynthia pryeri. Scanning electron microscopic analysis demonstrated the presence of two major types of cells in the body fluid isolated from the thoracic region of a pupa. Phagocytosis and encapsulation, characteristics of innate cellular reactions, by these cells were observed when latex beads as foreign targets were microinjected into the internal portion of a pupa. Such behavior by these cells was still observed even when pupae were continuously chilled at 4°C. Our results indicate that innate cellular reactions can work in diapausing insects in a dormant state.

Lipid rafts: keys to sperm maturation, fertilization, and early embryogenesis

Cell membranes are composed of many different lipids and protein receptors, which are important for regulating intracellular functions and cell signaling. To orchestrate these activities, the cell membrane is compartmentalized into microdomains that are stably or transiently formed. These compartments are called "lipid rafts". In gamete cells that lack gene transcription, distribution of lipids and proteins on these lipid rafts is focused during changes in their structure and functions such as starting flagella movement and membrane fusion. In this paper, we describe the role of lipid rafts in gamete maturation, fertilization, and early embryogenesis.

Mice lacking two sperm serine proteases, ACR and PRSS21, are subfertile, but the mutant sperm are infertile in vitro

Although sperm serine protease and proteasome have long been believed to play an important role in the fertilization process, the molecular mechanism is still controversial. In this study, we have produced double-knockout mice lacking two sperm serine proteases, ACR and PRSS21, to uncover the functional role of the trypsinlike activity in fertilization. The double-knockout male mice were subfertile, likely owing to the incompleteness of fertilization in the oviductal ampulla. Despite male subfertility, the mutant epididymal sperm exhibited the inability to undergo acrosomal exocytosis on the zona pellucida (ZP) surface and to traverse the ZP, thus resulting in the failure of fertilization in vitro. The double-knockout epididymal sperm were also defective in penetration through the cumulus matrix to reach the ZP. When epididymal sperm were artificially injected into the uterus of wild-type mice, the 2-cell embryos, which had previously been fertilized by double-knockout sperm, were recovered at a low but significant level. The mutant epididymal sperm were also capable of fertilizing the oocytes in the presence of uterine fluids in vitro. These data demonstrate that the trypsinlike protease activity of ACR and PRSS21 is essential for the process of sperm penetration through the cumulus matrix and ZP in vitro, and suggest that the female reproductive tract partially compensates for the loss of the sperm function. We therefore conclude that the sperm trypsinlike activity is still important but not essential for fertilization in vivo in the mouse.

Functional implications of membrane modification with semenogelins for inhibition of sperm motility in humans

Semenogelin I and II (Sgs) are the major component of human semen coagulum. The protein is rapidly cleaved after ejaculation by a prostate-specific antigen, resulting in liquefaction of the semen coagulum and the progressive release of motile spermatozoa. Sgs inhibit human sperm motility; however, there is currently no information on its effect on the sperm membrane. This study investigated the role of Sgs on human sperm motility through regulation of membrane potential and membrane permeability. Fresh semen samples were obtained from normozoospermic volunteers, and studies were conducted using motile cells selected using the swim-up method. Sgs changed the characteristics of sperm motion from circular to straightforward as evaluated by a computer-assisted motility analyzer, and all parameters were decreased more than 2.5 mg/mL. The results demonstrate that Sgs treatment immediately hyperpolarized the membrane potential of swim-up-selected sperm, changed the membrane structure, and time-dependently increased membrane permeability, as determined through flow cytometric analysis. The biphasic effects of Sgs were time- and dose-dependent and partially reversible. In addition, a monoclonal antibody against Sgs showed positive binding to cell membrane proteins in fixed cells, observed with confocal fluorescence microscopy. These results demonstrate that Sgs modifies the membrane structure, indirectly inhibiting motility, and provides suggestions for a therapy for male infertility through selection of a functional sperm population using Sgs.

Control of sperm motility and fertility: diverse factors and common mechanisms

Spermatozoa generated in the testis are immature and incompetent for fertilization. During their journey toward the egg, the sperm acquire fertility and achieving fertilization. These sperm modifications to ensure fertilization are induced by many female or male extra-sperm factors: for example, sperm motility-activating factors from the egg jelly, sperm attractants from the eggs, and decapacitation factors from the seminal plasma. The factors controlling sperm fertility are myriad and species specific; they may be peptides, sugar chains, or small organic compounds. Nevertheless, the fundamental mechanisms underlying fertilization must be common among all animals; increase in [Ca(2+)](i) triggers all the steps in the process of fertilization, and cAMP plays important roles in many steps. Elucidating the dynamic functional and morphological changes in sperm cells is important for understanding the regulation of fertilization. Here, we introduce the diversity and generality of the control of sperm fertility.

Physiological roles of semenogelin I and zinc in sperm motility and semen coagulation on ejaculation in humans

At ejaculation, human sperm are considered to be mechanically trapped and become immotile in the semen coagulum by binding to semenogelins (Sgs) from the seminal vesicle and zinc ions from the prostate. However, the physiological combined roles of the protein and heavy metal on sperm motility are unknown. Here, we have first demonstrated that Sg I alone, which does not form the semen coagulum without zinc, is an inhibitor of the motility of intact human sperm at physiological concentration. On the other hand, zinc ions alone had no effect on sperm motility, but confer recovery of sperm motility that has been inhibited by Sg I at a concentration equal to or less than 1 mg/ml. These observations suggest that the roles played by Sg I and zinc on sperm motility are not mechanical but physiological. Quartz crystal microbalance analysis suggests that the sperm extract first bind to Sg I and then zinc ions which subsequently increase the protein accumulation, suggesting that Sgs inhibit sperm motility by directly binding to the sperm surface. Further accumulation of Sg I mediated by zinc ions may entrap the quiescent sperm at semen ejaculation.

Semen-coagulating protein, SVS2, in mouse seminal plasma controls sperm fertility

Mammalian seminal plasma is known to contain a decapacitation factor(s) that prevents capacitation and thus, the fertility of sperm. This phenomenon has been observed in experiments conducted in vitro that assessed the inhibition of epididymal sperm fertility by seminal plasma or by the purified decapacitation factor. However, the phenomenon of decapacitation has not yet been characterized in vivo. In the present study, we demonstrate that seminal vesicle protein secretion 2 (SVS2), which is a 40-kDa basic protein and a major component of the copulatory plug, enters the uterus and interacts with ejaculated sperm heads after copulation. The SVS2-binding region of sperm changed from the postacrosomal region to the equatorial segment, while the sperm migrated through the uterus and finally disappeared in the oviduct. Furthermore, SVS2 reduced the fertility of epididymal sperm. The sperm treated with SVS2 decreased the percentage of fertilized oocytes from 60% to 10%. The capacitation state was assessed by protein tyrosine phosphorylation and the comprehensiveness of the acrosome reaction. SVS2 functioned to maintain sperm in the uncapacitated state and to reverse capacitated sperm to the uncapacitated state. We found that the fertility of ejaculated sperm is associated with SVS2 distribution in the female reproductive tract. These results indicate that SVS2 functions as a decapacitation factor for mouse sperm.