Seminal fluid signaling in the female reproductive tract: lessons from rodents and pigs.
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Seminal fluid contains potent signaling agents that influence female reproductive physiology to improve the chances of conception and pregnancy success. Cytokines and prostaglandins synthesized in the male accessory glands are transferred to the female at insemination, where they bind to receptors on target cells in the cervix and uterus, activating changes in gene expression that lead to modifications in structure and function of the female tissues. The consequences are increased sperm survival and fertilization rates, conditioning of the female immune response to tolerate semen and the conceptus, and molecular and cellular changes in the endometrium that facilitate embryo development and implantation. Male-female tract signaling occurs in rodents, livestock animals, and all other mammals examined thus far, including humans. In mice, the key signaling moieties in seminal plasma are identified as members of the transforming growth factor-beta family. Recent studies indicate a similar signaling function for boar factors in the pig, whereby the sperm and plasma fractions of seminal fluid appear to synergize in activating an inflammatory response and downstream changes in the female tract after insemination. Seminal plasma elicits endometrial changes, with induction of proinflammatory cytokines and cyclooxygenase-2, causing recruitment of macrophages and dendritic cells. Sperm contribute by interacting with seminal plasma factors to modulate neutrophil influx into the luminal cavity. The cascade of changes in local leukocyte populations and cytokine synthesis persists throughout the preimplantation period. Exposure to seminal fluid alters the dynamics of preimplantation embryo development, with an increase in the number of fertilized oocytes attaining the viable blastocyst stage. There is also evidence that seminal factors influence the timing of ovulation, corpus luteum development, and progesterone synthesis. Insight into the molecular basis of seminal fluid signaling in the female reproductive tract may inform new interventions and management practices to ensure maximal fertility and reduce embryo mortality in pigs and, potentially, other livestock species. (+info)
Paternal antigen-bearing cells transferred during insemination do not stimulate anti-paternal CD8+ T cells: role of estradiol in locally inhibiting CD8+ T cell responses.
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Maternal immunological tolerance of the semiallogeneic fetus involves several overlapping mechanisms to balance maternal immunity and fetal development. Anti-paternal CD8+ T cells are suppressed during pregnancy in some but not all mouse models. Since semen has been shown to mediate immune modulation, we tested whether exposure to paternal Ag during insemination activated or tolerized anti-paternal CD8+ T cells. The uterine lumen of mated female mice contained male MHC I+ cells that stimulated effector, but not naive, CD8+ T cells ex vivo. Maternal MHC class I+ myeloid cells fluxed into the uterine lumen in response to mating and cross-presented male H-Y Ag to effector, but not naive, CD8+ T cells ex vivo. However, neither unprimed nor previously primed TCR-transgenic CD8+ T cells specific for either paternal MHC I or H-Y Ag proliferated in vivo after mating. These T cells subsequently responded normally to i.p. challenge, implicating ignorance rather than anergy as the main reason for the lack of response. CD8+ T cells responded to either peptide Ag or male cells delivered intravaginally in ovariectomized mice, but this response was inhibited by systemic estradiol (inducing an estrus-like state). Subcutaneous Ag induced responses in both cases. Allogeneic dendritic cells did not induce responses intravaginally even in ovariectomized mice in the absence of estradiol. These results suggest that inhibition of antiallogeneic responses is restricted both locally to the reproductive tract and temporally to the estrous phase of the menstrual cycle, potentially decreasing the risk of maternal immunization against paternal Ags during insemination. (+info)
Traumatic insemination in the plant bug genus Coridromius Signoret (Heteroptera: Miridae).
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In traumatic insemination, males pierce females with hypodermic genitalia and ejaculate into the body cavity rather than into the genital tract. This has resulted in the evolution of female counter-adaptations in the form of paragenitalia to reduce the direct physical costs of mating. While rare in the animal kingdom, traumatic insemination is oddly prevalent in the true bug infraorder Cimicomorpha (Heteroptera), where it occurs in six families and is thought to have arisen twice. Here, we report the discovery of traumatic insemination and elaborate paragenital development in the plant bug genus Coridromius (Miridae), representing a third, independent emergence of traumatic insemination in this infraorder. (+info)
Strategic sperm allocation under parasitic sex-ratio distortion.
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Parasitic sex-ratio distorters are a major selective force in the evolution of host mating behaviour and mate choice. Here, we investigate sperm limitation in the amphipod Gammarus duebeni and the impact of the microsporidian sex-ratio distorter Nosema granulosis on sperm allocation strategies. We show that males become sperm limited after three consecutive matings and provide uninfected, high fecundity, females with more sperm than infected females. We show that sperm limitation leads to a decrease in female productivity. The outcome of sex-ratio distortion has been shown theoretically to be sensitive to the mating limits of males. Our results indicate that strategic sperm allocation under male rarity will have a greater impact on infected females and has the potential to regulate spread of parasitic feminisers in host populations. (+info)
Adenovirus-mediated gene delivery into mouse spermatogonial stem cells.
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Spermatogonial stem cells represent a self-renewing population of spermatogonia, and continuous division of these cells supports spermatogenesis throughout the life of adult male animals. Previous attempts to introduce adenovirus vectors into spermatogenic cells, including spermatogonial stem cells, have failed to yield evidence of infection, suggesting that male germ cells may be resistant to adenovirus infection. In this study we show the feasibility of transducing spermatogonial stem cells by adenovirus vectors. When testis cells from ROSA26 Cre reporter mice were incubated in vitro with a Cre-expressing adenovirus vector, Cre-mediated recombination occurred at an efficiency of 49-76%, and the infected spermatogonial stem cells could reinitiate spermatogenesis after transplantation into seminiferous tubules of infertile recipient testes. No evidence of germ-line integration of adenovirus vector could be found in offspring from infected stem cells that underwent Cre-mediated recombination, which suggests that the adenovirus vector infected the cells but did not stably integrate into the germ line. Nevertheless, these results suggest that adenovirus may inadvertently integrate into the patient's germ line and indicate that there is no barrier to adenovirus infection in spermatogonial stem cells. (+info)
Twin intromittent organs of Drosophila for traumatic insemination.
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In several animals, male genitalia create insemination wounds in areas outside the genital orifice of females. I report that such traumatic insemination (TI) occurs in the Drosophila bipectinata complex (Diptera: Drosophilidae) and illustrate a previously unknown evolutionary pathway for this behaviour. Flash fixation of mating pairs revealed the dual function of the paired claw-like basal processes, previously misidentified as a bifid aedeagus: (i) penetration of the female body wall near the genital orifice and (ii) sperm transfer into the genital tract through the wounds. Basal processes in closely related species (Drosophila ananassae and Drosophila pallidosa) also wounded females but did not transfer sperm; this represents a transitional state to TI as observed in the bipectinata complex. Copulatory wounding is suggested to occur in other allied species of the Drosophila melanogaster species group, including D. melanogaster. Ubiquitous sexual conflicts over mating may have led to the evolution of novel intromittent organs for insemination. (+info)
Pregnancy loss in dairy cows: the contributing factors, the effects on reproductive performance and the economic impact.
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This study investigated the effects of the herd, cow parity, the insemination protocol and season on the incidence of pregnancy loss (PL) in dairy herds. Furthermore, we determined the downstream effects of PL on reproductive performance and its economic impact. The overall incidence rate of PL was 6.9% in 1,001 pregnant cows and its incidence peaked (p < 0.01) during the second trimester of gestation. GLIMMIX analysis revealed that cow parity was the important risk factor for the PL. The odds ratio showed that the likelihood of PL in cows with parities of 1 or 2 was decreased by 0.6 or 0.5 fold compared to the cows with a parity of 3 or higher. Following PL, the mean rate of endometritis was 23.2% and endometritis was more common (p < 0.05) when PL occurred during the third trimester than during the first and second trimesters. The mean culling rate was 46.4% and this did not differ with the period of PL. The overall mean intervals from PL to the first service and conception were 63.4 and 101.8 days, respectively. The mean interval from PL to first service was longer (p < 0.01) for cows with PL during the third trimester than for the cows with PL during the first and second trimesters. The economic loss resulting from each PL was estimated at approximately $2,333, and this was largely due to an extended calving interval and increased culling. These results suggest that cow parity affects the incidence of PL, which extends calving interval and causes severe economic loss of dairy herds. (+info)
Effects of insemination quantity on honey bee queen physiology.
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Mating has profound effects on the physiology and behavior of female insects, and in honey bee (Apis mellifera) queens, these changes are permanent. Queens mate with multiple males during a brief period in their early adult lives, and shortly thereafter they initiate egg-laying. Furthermore, the pheromone profiles of mated queens differ from those of virgins, and these pheromones regulate many different aspects of worker behavior and colony organization. While it is clear that mating causes dramatic changes in queens, it is unclear if mating number has more subtle effects on queen physiology or queen-worker interactions; indeed, the effect of multiple matings on female insect physiology has not been broadly addressed. Because it is not possible to control the natural mating behavior of queens, we used instrumental insemination and compared queens inseminated with semen from either a single drone (single-drone inseminated, or SDI) or 10 drones (multi-drone inseminated, or MDI). We used observation hives to monitor attraction of workers to SDI or MDI queens in colonies, and cage studies to monitor the attraction of workers to virgin, SDI, and MDI queen mandibular gland extracts (the main source of queen pheromone). The chemical profiles of the mandibular glands of virgin, SDI, and MDI queens were characterized using GC-MS. Finally, we measured brain expression levels in SDI and MDI queens of a gene associated with phototaxis in worker honey bees (Amfor). Here, we demonstrate for the first time that insemination quantity significantly affects mandibular gland chemical profiles, queen-worker interactions, and brain gene expression. Further research will be necessary to elucidate the mechanistic bases for these effects: insemination volume, sperm and seminal protein quantity, and genetic diversity of the sperm may all be important factors contributing to this profound change in honey bee queen physiology, queen behavior, and social interactions in the colony. (+info)