Search

• Direct to consumer genetic testing (DTCGT) is changing the way information about donor conception is accessed. • DTCGT affects how people find and share information about donor conception. • DTCGT can affect parents, donors and donor-conceived people. • It can also affect peoples' extended family and other relatives. • Support and information should be provided for all those affected by these changes. What effect does direct-to-consumer genetic testing (DTCGT) have on information finding and sharing in relation to gamete donor conception? This study used in-depth qualitative interviews with parents through donor conception, donors, the relatives of donors and donor-conceived people who have used, or considered using, DTCGT. Interviews were conducted between September 2021 and February 2023. Sixty people defined themselves as having been affected by donor conception and DTCGT. Fifty-seven of these were resident in the UK at the time of interview. The final sample included 19 (spermatozoa, egg or embryo) donors, 25 donor-conceived people, 20 parents through donor conception and two relatives of donors. Five participants occupied more than one of these roles. The rise of DTCGT is affecting how information about donor conception is managed: it shifts patterns of knowledge about donor conception; increases flexibility regarding the age of access to information about donor relatives; can lead to a growing role for non-professionals, including wider family members, in gatekeeping information about donor conception; accentuates the effect of donor conception for donors' and the relatives of donor-conceived people; and shapes, and is shaped, by the formal regulatory donor information management systems. Fertility professionals should inform people using, or considering, donor conception, or (potential) donors, about the different ways DTCGT can affect sharing information about donor conception. Support is needed for those affected by these changes. [ABSTRACT FROM AUTHOR]

Three genes are known to be essential for gamete adhesion/fusion (Cd9, Izumo1 and Juno). Here, we confirmed that Spaca6 null males are infertile and showed that their sperm accumulate in the perivitelline space but are unable to fuse with oocyte. Like IZUMO1, SPACA6 which is expressed by human sperm, is remained on the equatorial segment after acrosomal reaction and is involved in human fertilization since an anti-SPACA6 antibody inhibited it. Despite the similarity of the phenotypes caused by Spaca6 and Izumo1 knockouts, these are not redundant and the essential relocation of IZUMO1 is not affected by the lack of SPACA6. We propose a model in which IZUMO1 and SPACA6 would be part of a molecular complex necessary for gamete fusion and that their concomitant presence would be required for the recruitment of another essential molecular actor, such as a fusogen, for the fusion to take place. [ABSTRACT FROM AUTHOR]

Fertilization is a key biological process in which the egg and sperm must recognize one another and fuse to form a zygote. Although the process is a continuum, mammalian fertilization has been studied as a sequence of steps: sperm bind and penetrate through the zona pellucida of the egg, adhere to the egg plasma membrane and finally fuse with the egg. Following fusion, effective blocks to polyspermy ensure monospermic fertilization. Here, we review how recent advances obtained using genetically modified mouse lines bring new insights into the molecular mechanisms regulating mammalian fertilization. We discuss models for these processes and we include studies showing that these mechanisms may be conserved across different mammalian species. [ABSTRACT FROM AUTHOR]

Transition from isogamy to anisogamy, hence males and females, leads to sexual selection, sexual conflict, sexual dimorphism, and sex roles. Gamete dynamics theory links biophysics of gamete limitation, gamete competition, and resource requirements for zygote survival and assumes broadcast spawning. It makes testable predictions, but most comparative tests use volvocine algae, which feature internal fertilization. We broaden this theory by comparing broadcast-spawning predictions with two plausible internal-fertilization scenarios: gamete casting/brooding (one mating type retains gametes internally, the other broadcasts them) and packet casting/brooding (one type retains gametes internally, the other broadcasts packets containing gametes, which are released for fertilization). Models show that predictions are remarkably robust to these radical changes, yielding (1) isogamy under low gamete limitation, low gamete competition, and similar required resources for gametes and zygotes, (2) anisogamy when gamete competition and/or limitation are higher and when zygotes require more resources than gametes, as is likely as multicellularity develops, (3) a positive correlation between multicellular complexity and anisogamy ratio, and (4) under gamete competition, only brooders becoming female. Thus, gamete dynamics theory represents a potent rationale for isogamy/anisogamy and makes similar testable predictions for broadcast spawners and internal fertilizers, regardless of whether anisogamy or internal fertilization evolved first. [ABSTRACT FROM AUTHOR]

The temporal expansion of harmful algal blooms, primarily associated with cyanobacteria, may impact aquatic organisms at vulnerable life‐history stages. Broadcast spawning species release gametes into the water column for external fertilization, directly exposing sperm to potential aquatic stressors. To determine if cyanobacteria can disrupt reproduction in freshwater broadcast spawners, we evaluated sublethal effects of cyanobacteria exposure on quagga mussel (Dreissena rostriformis bugensis) sperm. In laboratory studies, sperm were collected after inducing mussels to spawn using serotonin and exposed to 11 cultures of cyanobacteria including Anabaena flos‐aquae, Aphanizomenon flos‐aquae, Dolichospermum lemmermannii, Gloeotrichia echinulata, 5 cultures of Microcystis aeruginosa, M. wesenbergii, and Planktothrix suspensa. Sperm motility, using endpoints of cumulative distance traveled and mean velocity, was calculated for a minimum of 10 individual sperm using a novel optical biotracking assay method. The distance and velocity at which sperm traveled decreased when exposed to Aphanizomenon flos‐aquae and 2 M. aeruginosa cultures. Our findings indicate that cyanobacteria impede the motility of quagga mussel sperm, which can potentially result in reproductive impairments to mussels and potentially other broadcast spawning species. Environ Toxicol Chem 2019;38:368–374. © 2018 SETAC [ABSTRACT FROM AUTHOR]

The idea that male reproductive strategies evolve primarily in response to sperm competition is almost axiomatic in evolutionary biology. However, externally fertilizing species, especially broadcast spawners, represent a large and taxonomically diverse group that have long challenged predictions from sperm competition theory—broadcast spawning males often release sperm slowly, with weak resource‐dependent allocation to ejaculates despite massive investment in gonads. One possible explanation for these counter‐intuitive patterns is that male broadcast spawners experience strong natural selection from the external environment during sperm dispersal. Using a manipulative experiment, we examine how male reproductive success in the absence of sperm competition varies with ejaculate size and rate of sperm release, in the broadcast spawning marine invertebrate Galeolaria caespitosa (Polychaeta: Serpulidae). We find that the benefits of Fast or Slow sperm release depend strongly on ejaculate size, but also that the per‐gamete fertilization rate decreases precipitously with ejaculate size. Overall, these results suggest that, if males can facultatively adjust ejaculate size, they should slowly release small amounts of sperm. Recent theory for broadcast spawners predicts that sperm competition can also select for Slow release rates. Taken together, our results and theory suggest that selection often favours Slow ejaculate release rates whether males experience sperm competition or not. [ABSTRACT FROM AUTHOR]

Four recently-diverged species of Indo-Pacific sea urchins, belonging to the genus Echinometra, occur most abundantly and sympatrically along the coast of Okinawa Island, southern Japan. Among them, the two most distinct species--Echinometra sp. A (Ea) and Echinometra mathaei (Blainville, 1825) (Em)--were examined for potential hybridization through a series of cross-fertilization and hybrid raising experiments. Compared to conspecifk crosses, fertilization rates in both heterospecific crosses were very low, even at a very high concentration of sperm. At limited sperm concentration, where conspecifk crosses achieved near 100% fertilization, heterospecific crosses had <3% fertilization success. This strong block to fertilization in either heterospecific cross indicates the presence of a protein-binding system for gamete recognition. A significantly lower survival rate in larvae, juveniles, and adults does indicate a postzygotic isolating mechanism that is strong enough to limit hybrid survival, but is not complete, and did in fact cause some amount of developmental incompatibility or hybrid inviability. In adults, Em (ova) x Ea (sperm) was largest in live weight, followed by Ea (ova) x Em (sperm), Ea x Ea, and Em x Em, in that order. Other growth performances, such as test sizes, gonad weight, and gonad index of hybrids and their conspecifics, also followed the same trend as live weight. Phenotypic color patterns of the hybrids were maternally inherited, while other characters (spine length, morphology of tubefoot and gonad spicules, pedicellaria valve length, and gamete sizes) were intermediate. Ova and sperm of the F, hybrids were fertile in backcrosses, minimizing the possibility that hybrid infertility is a postzygotic isolating mechanism. Nevertheless, intensive surveys failed to find individuals with such hybrid characteristics, suggesting a very low presence or complete absence of natural hybrids in the field. This strongly suggests that pre- and postzygotic isolating mechanism(s) are isolating these species. Among these mechanisms, strong gametic incompatibility and probably microhabitat separation, differences in spawning times, gamete competition, or other factors appear to be important for maintaining genetic integrity of these two species. [ABSTRACT FROM AUTHOR]

Lilies (Lilium spp.) are one of the most important floricultural crops. As most lily cultivars have originated from interspecific hybridization, they usually have complex genome composition and occasionally fail to develop normal gametes. Further improvement of lily cultivars by sexual crossing requires evaluation of gamete development and subsequent male and female fertility. Although male fertility is easily evaluated through microscopic observation after staining or by pollen culture for germination, evaluation of female fertility is difficult, because gametes develop inside an ovule within an ovary. Lilium species have the Fritillaria type of embryo sac, which, at maturity, consists of a haploid egg apparatus, including one haploid egg cell and two haploid synergids, two polar nuclei (one haploid nucleus and one triploid nucleus) and three triploid antipodal cells. Compared to the Polygonum type of embryo sac, composition of the embryo in the Fritillaria type of embryo sac is complex. We developed an efficient microscopic observation technique for ovules using the clearing procedure, which allowed us to categorize abnormal patterns of female gametes and to elucidate the frequency of abnormal female gamete development. The relationship among normal embryo sac, pollen stainability and seed formation in lily cultivars is discussed. [ABSTRACT FROM AUTHOR]

Sex has consequences—indeed, where would we be without it? Yet for all its importance, remarkably little is known about how sex evolved, why it has persisted, or even what mechanisms allow sperm–egg fusion to occur. Fortunately, answers to these questions are beginning to emerge with studies of hapless 2/generative cell specific1 (HAP2/GCS1), a molecular machine that promotes gamete fusion in organisms ranging from protists to flowering plants and insects. In studies by Fedry and colleagues, key structural features of the HAP2 protein are revealed for the first time, lending new insights into its mode of action and reinforcing its relationship to viral proteins that accomplish a similar task and may be intimately linked to the origins of cell–cell fusion events (including sexual reproduction) across evolutionary time. [ABSTRACT FROM AUTHOR]

'Sperm competition'--where ejaculates from two or more males compete for fertilization--and 'cryptic female choice'--where females bias this contest to suit their reproductive interests--are now part of the everyday lexicon of sexual selection. Yet the physiological processes that underlie these postejaculatory episodes of sexual selection remain largely enigmatic. In this review, we focus on a range of post-ejaculatory cellular- and molecularlevel processes, known to be fundamental for fertilization across most (if not all) sexually reproducing species, and point to their putative role in facilitating sexual selection at the level of the cells and gametes, called 'gamete-mediated mate choice' (GMMC). In this way, we collate accumulated evidence for GMMC across different mating systems, and emphasize the evolutionary significance of such non-random interactions among gametes. Our overall aim in this review is to build a more inclusive view of sexual selection by showing that mate choice often acts in more nuanced ways than has traditionally been assumed.We also aim to bridge the conceptual divide between proximal mechanisms of reproduction, and adaptive explanations for patterns of non-random sperm--egg interactions that are emerging across an increasingly diverse array of taxa. [ABSTRACT FROM AUTHOR]

The time period during which oocyte and spermatozoa retain their fertilizing ability after contacting with water was evaluated in pikeperch (Sander lucioperca). In addition, success of in vitro fertilization was examined regarding to the sperm-to-oocyte ratio (SOR). In the first trial, oocytes were placed in Petri dishes containing 5 ml of the hatchery water, to which freshly collected and pooled sperm were added to each sample at 0, 15, 30, 60, 90, 120, 150 and 180 s post oocyte activation. The oocytes retained their fertility for at least 30 s after contacting with water. The second trial tested the maximum time period during which spermatozoa retained fertilizability after contacting with water. Milt (50 μl) was collected from each male and added to 5 ml of water in Petri dishes. Thereafter, oocytes were added at 0, 5, 15, 30, 60 and 75 s post-sperm activation. Delays exceeding 10 s affected negatively the fertilization success. The third trial examined the optimum SOR; in which was found that 100 × 103 spermatozoa per oocyte were the minimum ratio to ensure fertilization rates above 70%. Overall, the data clarified some biological interactions of gametes in the artificial propagation of pikeperch. [ABSTRACT FROM AUTHOR]

Summary: In flowering plants, cell–cell communication plays a key role in reproductive success, as both pollination and fertilization require pathways that regulate interactions between many different cell types. Some of the most critical of these interactions are those between the pollen tube (PT) and the embryo sac, which ensure the delivery of sperm cells required for double fertilization. Synergid cells function to attract the PT through secretion of small peptides and in PT reception via membrane‐bound proteins associated with the endomembrane system and the cell surface. While many synergid‐expressed components regulating PT attraction and reception have been identified, few tools exist to study the localization of membrane‐bound proteins and the components of the endomembrane system in this cell type. In this study, we describe the localization and distribution of seven fluorescent markers that labelled components of the secretory pathway in synergid cells of Arabidopsis thaliana. These markers were used in co‐localization experiments to investigate the subcellular distribution of the two PT reception components LORELEI, a GPI‐anchored surface protein, and NORTIA, a MILDEW RESISTANCE LOCUS O protein, both found within the endomembrane system of the synergid cell. These secretory markers are useful tools for both reproductive and cell biologists, enabling the analysis of membrane‐associated trafficking within a haploid cell actively involved in polar transport. [ABSTRACT FROM AUTHOR]

The evolution of gametic compatibility and the effectiveness of compatibility, within and across species, depend on whether sperm from different males directly compete for an egg and whether eggs ever have a choice. Direct sperm competition and egg choice depend on whether sperm from different males arrive at an egg in the brief interval between first sperm contact and fertilization. Although this process may be relevant for all sexually reproducing organisms, it is most easily examined in aquatic external fertilizers. When spermare released into the sea, packets of seawater at the spatial scale relevant to single eggs might contain sperm from only one male, eliminating the potential for direct sperm competition and egg choice. Field experiments and a simple heuristic model examining the degree of sperm mixing for the sea urchin Strongylocentrotus franciscanus indicate that degree of competitive fertilization depends on density and distribution of competing males and that the nature of this competition influences whether males with high- or low-affinity gamete recognition protein genotypes have higher reproductive success. These results provide a potential explanation for the generation and maintenance of variation in gamete recognition proteins and why effectiveness of conspecific sperm precedence can be density dependent. [ABSTRACT FROM AUTHOR]

Study Question: What is the effect of a combination of three antioxidants (Acetyl-L-Carnitine, N-Acetyl-L-Cysteine and α-Lipoic Acid), present in IVF medium during mouse oocyte and sperm collection, on fertilization and subsequent IVF embryo development?Summary Answer: A combination of antioxidants resulted in faster developmental times from the 2-cell stage through to expanded blastocyst stage, accompanied by a significant increase in blastocyst cell number and a reduction of intracellular hydrogen peroxide (H2O2) levels.What Is Known Already: The antioxidant combination Acetyl-L-Carnitine, N-Acetyl-L-Cysteine and α-Lipoic Acid, when present in embryo culture media, has a significant beneficial effect on in vitro fertilized mouse pronucleate oocyte development, especially under oxidative stress.Study Design, Size, Duration: IVF was conducted with combined antioxidants supplemented in IVF medium that was used for mouse oocyte collection and fertilization (oocyte IVF medium, 4 h exposure) and sperm collection and preparation (sperm IVF medium, 1 h exposure).Participants/materials, Settings, Methods: IVF was conducted under 20% oxygen, in the presence or absence of a combination of antioxidants (10 μM Acetyl-L-Carnitine, 10 μM N-Acetyl-L-Cysteine, 5 μM α-Lipoic Acid) and resultant embryos cultured with and without antioxidants under 20% oxygen. Subsequently, the effects of antioxidants on either oocytes or sperm was evaluated. Embryo development was analysed through time-lapse microscopy followed by differential nuclear staining to determine cell allocation in the blastocyst. Intracellular levels of H2O2 were assessed using an aryl boronate probe after 4 h of incubation with antioxidants. Controls were gametes and embryos that had no antioxidants in the medium. In a separate series of experiments, pronucleate oocytes were collected in handling medium with and without antioxidants for 20 min and subsequent cell numbers analysed.Main Results and the Role Of Chance: Antioxidant treatment during both IVF and culture resulted in significantly faster development times to two cell cleavage (P < 0.01), which continued through to the expanded blastocyst stage (P < 0.05). Resultant blastocysts had a significant increase in both trophectoderm (TE) cell numbers, inner cell mass (ICM) and total cell numbers (P < 0.001). The addition of antioxidants to IVF medium or embryo culture media exclusively also resulted in a significant increase in both blastocyst TE and ICM numbers leading to an increase in total cell numbers (P < 0.001). Antioxidant supplementation of either oocyte IVF medium alone, or in both oocyte and sperm IVF medium, lead to significantly faster times to two cell cleavage, which continued through to the expanded blastocyst stage. Blastocyst cell number in both these groups had significantly higher TE cell numbers resulting in an increase in total cell numbers. In contrast, there were no differences in embryo developmental rates and blastocyst cell number when antioxidants were present only in the sperm IVF medium. Levels of H2O2 were significantly reduced in pronucleate oocytes that were cultured in the presence of antioxidants (P < 0.001) compared to control, untreated embryos. Similarly, pronucleate oocytes treated with the combined antioxidants during pronucleate oocyte collection resulted in significantly increased blastocyst ICM numbers compared with controls (P < 0.05).Limitations, Reasons For Caution: Embryo development was only examined in the mouse.Wider Implications Of the Findings: These findings suggest that supplementation of antioxidants to the IVF medium, as well as to embryo culture media, may further assist in maintaining the viability of human embryos in ART, conceivably through the reduction of oxidative stress.Study Funding/competing Interest(s): This work was funded by a research grant from Vitrolife AB (Sweden). The authors have no conflict of interest to declare. [ABSTRACT FROM AUTHOR]

The oviductal microenvironment is a site for key events that involve gamete maturation, fertilization and early embryo development. Secretions into the oviductal lumen by either the lining epithelium or by transudation of plasma constituents are known to contain elements conducive for reproductive success. Although previous studies have identified some of these factors involved in reproduction, knowledge of secreted proteins in the oviductal fluid remains rudimentary with limited definition of function even in extensively studied species like cattle. In this study, we used a shotgun proteomics approach followed by bioinformatics sequence prediction to identify secreted proteins present in the bovine oviductal fluid (ex vivo) and secretions from the bovine oviductal epithelial cells (in vitro). From a total of 2087 proteins identified, 266 proteins could be classified as secreted, 109 (41%) of which were common for both in vivo and in vitro conditions. Pathway analysis indicated different classes of proteins that included growth factors, metabolic regulators, immune modulators, enzymes, and extracellular matrix components. Functional analysis revealed mechanisms in the oviductal lumen linked to immune homeostasis, gamete maturation, fertilization and early embryo development. These results point to several novel components that work together with known elements mediating functional homeostasis, and highlight the diversity of machinery associated with oviductal physiology and early events in cattle fertility. [ABSTRACT FROM AUTHOR]

A fundamental tenet of inheritance in sexually reproducing organisms such as humans and laboratory mice is that gametes combine randomly at fertilization, thereby ensuring a balanced and statistically predictable representation of inherited variants in each generation. This principle is encapsulated in Mendel's First Law. But exceptions are known. With transmission ratio distortion, particular alleles are preferentially transmitted to offspring. Preferential transmission usually occurs in one sex but not both, and is not known to require interactions between gametes at fertilization. A reanalysis of our published work in mice and of data in other published reports revealed instances where any of 12 mutant genes biases fertilization, with either too many or too few heterozygotes and homozygotes, depending on the mutant gene and on dietary conditions. Although such deviations are usually attributed to embryonic lethality of the underrepresented genotypes, the evidence is more consistent with genetically-determined preferences for specific combinations of egg and sperm at fertilization that result in genotype bias without embryo loss. This unexpected discovery of genetically-biased fertilization could yield insights about the molecular and cellular interactions between sperm and egg at fertilization, with implications for our understanding of inheritance, reproduction, population genetics, and medical genetics. [ABSTRACT FROM AUTHOR]

Although the effect of ocean acidification on fertilization success of marine organisms is increasingly well documented, the underlying mechanisms are not completely understood. The fertilization success of broadcast spawning invertebrates depends on successful sperm-egg collisions, gamete fusion, and standard generation of Ca 2+ oscillations. Therefore, the realistic effects of future ocean p CO 2 levels on these specific aspects of fertilization of Tegillarca granosa were investigated in the present study through sperm velocity trials, fertilization kinetics model analysis, and intracellular Ca 2+ assays, respectively. Results obtained indicated that ocean acidification significantly reduced the fertilization success of T. granosa , which could be accountable by (i) decreased sperm velocity hence reducing the probability for sperm-egg collisions; (ii) lowered probability of gamete fusion for each gamete collision event; and (iii) disrupted intracellular Ca 2+ oscillations. [ABSTRACT FROM AUTHOR]

As the taste receptor for monosodium glutamate (umami) is expressed in both murine and human spermatozoa and the presence of α-gustducin and α-transducin, G proteins involved in the umami taste signaling, has been described in boar germ cells, the aim of this study was to evaluate if monosodium glutamate (MSG) would exert any effect on sperm-oocyte binding, in vitro fertilization (IVF) and sperm parameters during in vitro induced capacitation. For sperm-zona pellucida binding assay, boar spermatozoa were preincubated for 1 h and then coincubated for 1 h with denuded in vitro matured oocytes in presence of different concentrations of MSG (0, 0.1, 1, 10 mM). MSG 1 and 10 mM significantly (P < 0.05) increased the mean number of sperm bound to ZP compared with control (12.3 ± 9.0, 17.8 ± 11.3, 17.6 ± 10.8, MSG 0, 1 and 10 mM respectively). For in vitro fertilization trials, both sperm preicubation (1 h) and gamete coincubation (1 h) were performed in presence of different concentrations of MSG (0, 0.1, 1, 10 mM). After 19 h of culture in fresh IVF medium, oocytes were fixed. MSG 1 mM significantly (P < 0.05) increased the penetration rate compared with control (53.7 ± 20.4 vs. 36.8 ± 16.2). The addition of MSG during in vitro induced capacitation of boar spermatozoa did not cause any significant difference, compared with control, on the percentage of viable cells, spermatozoa with intact acrosome and the percentage of spermatozoa displaying tyrosine - phosphorylation of sperm tail proteins. In order to evaluate whether the effect elicited by MSG could be due to glutamate uptake in boar spermatozoa, fertilization trials were performed in presence of either 1 mM MSG or 1 mM MSG + 100 μM DL- threo -beta-hydroxyaspartic acid (THA), a non selective inhibitor of glutamate uptake. A significant increase (P < 0.05) in the penetration rate in both MSG and MSG + THA groups compared to control was recorded (39.8 ± 15.7, 53.7 ± 22.1, 52.2 ± 23.7, Control, MSG and MSG + THA respectively) while no difference in penetration rate between MSG and MSG + THA treatment was observed suggesting that sperm glutamate transporters are not involved in the pathway mediating this effect. Our study demonstrates for the first time that glutamate exerts a positive effect on sperm-oocyte binding and fertilization. Further studies are needed to clarify the mechanism by which glutamate exert his effect. [ABSTRACT FROM AUTHOR]

When a spermatozoon fertilizes an oocyte in mammals, there must be an extremely precise regulation system for successful gamete fusion to occur, which is the final step of fertilization. Using gene-modified animals, IZUMO1 on the sperm side and its receptor, JUNO, on the ovum side, have been unveiled as indispensable factors for triggering membrane fusion. We recently analyzed the detailed molecular machinery of the IZUMO1-JUNO recognition system and clarified the tertiary architecture of the IZUMO1-JUNO complex based on the crystal structure. Over the past 2 years, important discoveries have successively emerged, presenting a new perspective on fertilization. In this mini-review, I will initially explain the historical background of the molecular mechanism study of gamete fusion, and go on to describe our latest study data. [ABSTRACT FROM AUTHOR]

Fertilization involving unreduced (2 n) gametes is considered the dominant mechanism of polyploid formation in angiosperms; however, our knowledge of the prevalence of and evolutionary mechanisms maintaining 2 n gametes in natural populations is limited. We hypothesize that 2 n gametes are deleterious consequences of meiotic errors maintained by mutation-selection balance and should increase in species with relaxed opportunities for selection on sexual processes (asexuality), reduced efficacy of selection (asexuality, selfing) and increased genome instability (high chromosome number)., We used flow cytometry to estimate male 2 n gamete production in 60 populations from 24 species of Brassicaceae. We quantified variation in 2 n gamete production within and among species, and examined associations with life history, reproductive mode, genome size and chromosomal number while accounting for phylogeny., Most individuals produced < 2% 2 n male gametes, whereas a small number had > 5% (up to 85%) production. Variation in 2 n gamete production was significant among species and related to reproductive system; asexual species produced significantly more 2 n gametes than mixed-mating and outcrossing species., Our results, unique in their multi-species perspective, are consistent with 2 n gametes being deleterious but maintained when opportunities for selection are limited. Rare individuals with elevated 2 n gamete production may be key contributors to polyploid formation. [ABSTRACT FROM AUTHOR]

We consider a mathematical model motivated by the studies of coral broadcast spawning in spatial dimensions two and three. We establish the local and global well-posedness of regular solutions for the model. We also prove that the total mass of the egg (sperm) density asymptotically approaches a strictly positive constant, provided that the efficiency of the absorbing reaction is strong enough. [ABSTRACT FROM AUTHOR]

We study the evolution of male and female mating strategies and mate choice for female fecundity and male fertilization ability in a system where both sexes can mate with multiple partners, and where there is variation in individual quality (i.e. in the availability of resources individuals can allocate to matings, mate choice and production of gametes). We find that when the cost of mating differs between sexes, the sex with higher cost of mating is reluctant to accept matings and is often also choosy, while the other sex accepts all matings. With equal mating costs, the evolution of mating strategies depends on the strength of female sperm limitation, so that when sperm limitation is strong, males are often reluctant and choosy, whereas females tend to accept available matings. Male reluctance evolves because a male's benefit per mating diminishes rapidly as he mates too often, hence losing out in the process of sperm competition as he spends much of his resources on mating costs rather than ejaculate production. When sperm limitation is weaker, females become more reluctant and males are more eager to mate. The model thus suggests that reversed sex roles are plausible outcomes of polyandry and limited sperm production. Implications for empirical studies of mate choice are discussed. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to investigate the photobiomodulation (PBM) effect of the 808 nm diode laser irradiation on spermatozoa, eggs, fertilized eggs, embryos, and larvae of Paracentrotus lividus, using two different power settings. Background data: Studies have shown the possible use of PBM in artificial insemination. These have shown the potential effect of low-power laser irradiation on spermatozoa, while there are few studies on the effect of laser photonic energy on oocytes and almost no reports on the influence of lasers in embryogenesis. Methods: P. lividus gametes, zygotes, embryos, and larvae were irradiated using the 808 nm diode laser (fluence 64 J/cm2 using 1 W or 192 J/cm2 with 3 W) with a flat-top hand-piece delivery, compared to a control without laser irradiation (0 J/cm2-0 W). The fertilization rate and the early developmental stages were investigated. Results: The fertilization ability was not affected by the sperm/egg irradiation. At the gastrula stage, no significant differences were observed compared with the control samples. In the late pluteus stage, there were no differences in the developmental percentage observed between the control and the treated samples (1 W), with the exception of larvae from gastrulae and larvae, which were irradiated at 3 W. Conclusions: This study has demonstrated that both the 64 J/cm2-1 W and the 192 J/cm2-3 W do not induce morphological damage on the irradiated P. lividus gametes whose zygotes generate normal embryos and larvae. Our data therefore support the assumption to use higher fluence in preliminary studies on in vitro fertilization. [ABSTRACT FROM AUTHOR]

Species may be prevented from interspecific hybridization by a number of different reproductive barriers that operate precopulatory and postcopulatory. In situation, when natural precopulatory reproductive barriers are affected by anthropogenic factors, postcopulatory reproductive barriers may be important for maintaining gametic isolation and hence preventing interspecific hybridization. This is highly topical in sturgeon (order Acipenseriformes) which exhibits remarkable ease of interspecific hybridization. The objectives of the present study were to evaluate the fertilization success of Acipenser ruthenus and Acipenser baerii spermatozoa under the interspecific competitive conditions and assessed, whether their spermatozoa tend to differentially fertilize eggs of conspecifics. We set up several in vitro fertilization experiments: (i) pooled eggs of both species were fertilized by sperm of each species separately; (ii) eggs of each species were fertilized by pooled sperm; (iii) pooled eggs were fertilized by pooled sperm and (iv) purebred and hybrid control groups. Using parental assignment by molecular markers, we found that when these species competed in pooled sperm, 78.9% of progeny were sired by A. ruthenus and 21.1% by A. baerii , demonstrating higher fertilization success for the former, irrespective of conspecificity of fertilized eggs. When pooled eggs were inseminated by A. ruthenus or A. baerii sperm separately, progeny almost equally comprised hybrid and purebred individuals. Hence, neither A. ruthenus nor A. baerii eggs showed a tendency to biased fertilization by spermatozoa of conspecific males. These findings together show that there may not be postcopulatory mechanisms preventing hybridization between A. ruthenus and A. baerii. [ABSTRACT FROM AUTHOR]

We evaluated the effect of high temperature on Apostichopus japonicus gametes. Gametes were exposed to the optimal temperature (18°C; control) or one of six high temperature treatments (26, 27, 28, 29, 30 and 31°C) and the cleavage rate ( CR) of fertilized eggs was measured as an indication of fertilization ability. At control temperatures (18°C), the male and female gametes had high fertilization ability ( CR ≥95.0%) in 5 h and the time at which 50% of gametes lost the ability to successfully fertilize ( LT50) was 7.03 h. All gametes were non-viable after 9 h. When male and female gametes were both exposed to high temperature, the LT50 was lower than that when female or male gametes were treated individually at the same high temperature ( P < 0.05). The LT50 was lower for male gametes treated alone than for female gametes treated alone. In conclusion, exposure to high temperature results in a decline in fertilization ability of A. japonicus gametes, and this decline was more rapid at higher temperature. The female gametes were more resistant to high temperatures than male gametes. [ABSTRACT FROM AUTHOR]

An important feature of fertilization is the asymmetric inheritance of centrioles. In most species it is the sperm that contributes the initial centriole, which builds the first centrosome that is essential for early development. However, given that centrioles are thought to be exceptionally stable structures, the mechanism behind centriole disappearance in the female germ line remains elusive and paradoxical. We elucidated a program for centriole maintenance in fruit flies, led by Polo kinase and the pericentriolar matrix (PCM): The PCM is downregulated in the female germ line during oogenesis, which results in centriole loss. Perturbing this program prevents centriole loss, leading to abnormal meiotic and mitotic divisions, and thus to female sterility. This mechanism challenges the view that centrioles are intrinsically stable structures and reveals general functions for Polo kinase and the PCM in centriole maintenance. We propose that regulation of this maintenance program is essential for successful sexual reproduction and defines centriole life span in different tissues in homeostasis and disease, thereby shaping the cytoskeleton. [ABSTRACT FROM AUTHOR]

Few animals are known to lay eggs in the absence of ovulation or copulation, as it is presumably energetically wasteful and subjected to negative selection. Characterization of Smed-boule, a member of the DAZ family of germline RNA-binding proteins, revealed that egg capsule (or capsule) production and deposition occurs independently of the presence of gametes in the planarian flatworm Schmidtea mediterranea. Reduction of Smed-boule expression by RNA-interference (RNAi) causes ablation of spermatogonial stem cells and the inability of ovarian germline stem cells to undergo oogenesis. Although animals subjected to Smed-boule RNAi lose their gametes and become sterile, they continue to lay egg capsules. Production of sterile capsules is even observed in virgin Smed-boule(RNAi) and control planarians maintained in complete isolation, demonstrating that egg production in S. mediterranea occurs independently of ovulation, fertilization, or mating. Evidence suggests that this is a conserved feature amongst Platyhelminthes, and therefore relevant to the pathology and dissemination of parasitic flatworms. These findings demonstrate that Smed-boule functions at different stages during male and female germline stem cell development, and also demonstrate that egg capsule production by planarian flatworms occurs independently of signals produced by mating or ova. [ABSTRACT FROM AUTHOR]

There is a clear tendency in nature for males to compete more strongly for fertilizations than females, yet the ultimate reasons for this are still unclear. Many researchers-dating back to Darwin and Bateman-have argued that the difference is ultimately driven by the fact that males (by definition) produce smaller and more numerous gametes than females. However, this view has recently been challenged, and a formal validation of the link between anisogamy and sex roles has been lacking. Here, we develop mathematical models that validate the intuition of Darwin and Bateman, showing that there is a very simple and general reason why unequal gamete numbers result in unequal investment in sexually competitive traits. This asymmetry does not require multiple mating by either sex, and covers traits such as mate searching, where the male bias has been difficult to explain. Furthermore, our models show males and females are predicted to diverge more strongly when the fertilization probability of each female gamete is high. Sex roles thus ultimately trace back to anisogamy and the resulting consequences for the fertilization process. [ABSTRACT FROM AUTHOR]

Competition among gametes for fertilization imposes strong selection. For external fertilizers, this selective pressure extends to eggs for which spawning conditions can range from sperm limitation (competition among eggs) to sexual conflict (overabundance of competing sperm toxic to eggs). Yet existing fertilization models ignore dynamics that can alter the functional nature of gamete interactions. These factors include attraction of sperm to eggs, egg crowding effects, or other nonlinearities in per capita rates of sperm-egg interaction. Such processes potentially allow egg concentrations to drastically affect viable fertilization probabilities. I experimentally tested whether such egg effects occur, using the urchin Strongylocentrotus purpuratus, and parameterized a newly derived model of fertilization dynamics and existing models modified to include such interactions. The experiments revealed that at low sperm concentrations, eggs compete for sperm, while at high sperm concentrations, eggs cooperatively reduce abnormal fertilization (a proxy for polyspermy). I show that these observations are consistent with declines in the per capita rate at which sperm and eggs interact as eggs increase in density. The results suggest a fitness trade-off of egg release during spawning: as sperm range from scarce to superabundant, interactions among eggs transition from highly competitive to cooperative in terms of viable fertilization probabilities. [ABSTRACT FROM AUTHOR]

Background: Plasmodium vivax 48/45 protein is expressed on the surface of gametocytes/gametes and plays a key role in gamete fusion during fertilization. This protein was recently expressed in Escherichia coli host as a recombinant product that was highly immunogenic in mice and monkeys and induced antibodies with high transmission-blocking activity, suggesting its potential as a P. vivax transmission-blocking vaccine candidate. To determine sequence polymorphism of natural parasite isolates and its potential influence on the protein structure, all pvs48/45 sequences reported in databases from around the world as well as those from low-transmission settings of Latin America were compared. Methods: Plasmodium vivax parasite isolates from malaria-endemic regions of Colombia, Brazil and Honduras (n = 60) were used to sequence the Pvs48/45 gene, and compared to those previously reported to GenBank and PlasmoDB (n = 222). Pvs48/45 gene haplotypes were analysed to determine the functional significance of genetic variation in protein structure and vaccine potential. Results: Nine non-synonymous substitutions (E35K, Y196H, H211N, K250N, D335Y, E353Q, A376T, K390T, K418R) and three synonymous substitutions (I73, T149, C156) that define seven different haplotypes were found among the 282 isolates from nine countries when compared with the Sal I reference sequence. Nucleotide diversity (p) was 0.00173 for worldwide samples (range 0.00033-0.00216), resulting in relatively high diversity in Myanmar and Colombia, and low diversity in Mexico, Peru and South Korea. The two most frequent substitutions (E353Q: 41.9 %, K250N: 39.5 %) were predicted to be located in antigenic regions without affecting putative B cell epitopes or the tertiary protein structure. Conclusions: There is limited sequence polymorphism in pvs48/45 with noted geographical clustering among Asian and American isolates. The low genetic diversity of the protein does not influence the predicted antigenicity or protein structure and, therefore, supports its further development as transmission-blocking vaccine candidate. [ABSTRACT FROM AUTHOR]

Although it is believed that mammalian sperm carry small noncoding RNAs (sncRNAs) into oocytes during fertilization, it remains unknown whether these sperm-borne sncRNAs truly have any function during fertilization and preimplantation embryonic development. Germline-specific Dicer and Drosha conditional knockout (cKO) mice produce gametes (i.e. spermand oocytes) partially deficient inmiRNAs and/or endo-siRNAs, thus providing a unique opportunity for testing whether normal sperm (paternal) or oocyte (maternal) miRNA and endo- siRNA contents are required for fertilization and preimplantation development. Using the outcome of intracytoplasmic sperm injection (ICSI) as a readout, we found that sperm with altered miRNA and endo-siRNA profiles could fertilize wild-type (WT) eggs, but embryos derived from these partially sncRNA-deficient sperm displayed a significant reduction in developmental potential, which could be rescued by injecting WT sperm-derived total or small RNAs into ICSI embryos. Disrupted maternal transcript turnover and failure in early zygotic gene activation appeared to associate with the aberrant miRNA profiles in Dicer and Drosha cKO spermatozoa. Overall, our data support a crucial function of paternal miRNAs and/or endosiRNAs in the control of the transcriptomic homeostasis in fertilized eggs, zygotes and two-cell embryos. Given that supplementation of sperm RNAs enhances both the developmental potential of preimplantation embryos and the live birth rate, it might represent a novel means to improve the success rate of assisted reproductive technologies in fertility clinics. [ABSTRACT FROM AUTHOR]

Abstract: Spermatogenesis is a key developmental process allowing for a formation of a mature male gamete. During its final phase, spermiogenesis, haploid round spermatids undergo cellular differentiation into spermatozoa, which involves extensive restructuring of cell morphology, DNA, and epigenome. Using mouse models with abrogated Y chromosome gene complements and Y-derived transgene we identified Y chromosome encoded Zfy2 as the gene responsible for sperm formation and function. In the presence of a Zfy2 transgene, mice lacking the Y chromosome and transgenic for two other Y-derived genes, Sry driving sex determination and Eif2s3y initiating spermatogenesis, are capable of producing sperm which when injected into the oocytes yield live offspring. Therefore, only three Y chromosome genes, Sry, Eif2s3y and Zfy2, constitute the minimum Y chromosome complement compatible with successful intracytoplasmic sperm injection in the mouse. [ABSTRACT FROM AUTHOR]

Initiation of mouse embryonic development depends upon a series of fertilization-induced rises in intracellularCa2+. Complete egg activation requires influx of extracellular Ca2+; however, the channels that mediate this influx remain unknown. Here, we tested whether the α1 subunit of the T-type channelCaV3.2, encoded by Cacna1h,mediates Ca2+ entry into oocytes. We show that mouse eggs express a robust voltage-activatedCa2+ current that is completely absent inCacna1h-/- eggs. Cacna1h-/- females have reduced litter sizes, and careful analysis of Ca2+ oscillation patterns in Cacna1h eggs following in vitro fertilization (IVF) revealed reductions in first transient length and oscillation persistence. Total and endoplasmic reticulum (ER) Ca2+ stores were also reduced in Cacna1h-/- eggs. Pharmacological inhibition of CaV3.2 in wild-type CF-1 strain eggs using mibefradil or pimozide reduced Ca2+ store accumulation during oocyte maturation and reduced Ca oscillation persistence, frequency and number following IVF. Overall, these data show that CaV3.2 T-type channels have prev8iously unrecognized roles in supporting the meiotic-maturation-associated increase in ER Ca2+ stores and mediating Ca2+2+ influx required for the activation of development. [ABSTRACT FROM AUTHOR]

The timing and synchrony of gamete release in broadcast spawners have important implications for fertilization success, recruitment and to explain differences in reproductive success under distinct reproductive modes in sympatry. Our objective was to compare the reproductive timing and investment for sister species with contrasting mating systems; Fucus guiryi (selfing hermaphroditic) and Fucus vesiculosus (dioecious) in habitats with different wave exposures (exposed shore and estuary). Over two months, daily gamete release, recruitment and population structure were recorded. Our results show spawning synchrony between species and habitats, but release events in hermaphrodites occupied broader temporal windows in estuarine than exposed shore habitats. On the exposed shore both species increased the synchrony of release and amount of eggs. In the estuary, hermaphrodites relied on broader temporal spawning windows and a larger canopy, and the dioecious species had higher recruitment success, important factors determining persistence. [ABSTRACT FROM AUTHOR]

The genetic benefits individuals receive from mate choice have been the focus of numerous studies, with several showing support for both intrinsic genetic benefits and compatibility effects on fertilization success and offspring viability. However, the robustness of these effects have rarely been tested across an ecologically relevant environmental gradient. In particular, sperm environment is a crucial factor determining fertilization success in many species, especially those with external fertilization. Here, we test the importance of sperm environment in mediating compatibility-based selection on fertilization using a factorial breeding design. We detected a significant intrinsic male effect on fertilization success at only one of four sperm concentrations. Compatibility effects were significant at the two highest sperm concentrations and, interestingly, the magnitude of the compatibility effect consistently increased with sperm concentration. This suggests that females are able to modify the probability of sperm-egg fusion as the amount of sperm available increases. [ABSTRACT FROM AUTHOR]

Mammalian fertilization involves a series of well-orchestrated cell–cell interaction steps between gametes, as well as among spermatozoa and somatic cells of both the male and female reproductive tracts. Cadherins are Ca 2+ -dependent glycoproteins that have been involved in cellular adhesion and signaling in somatic cells. Taking into account that Ca 2+ ions are required during fertilization, the involvement of these proteins in adhesion events during this process can be anticipated. This report presents an overview on two members of classical cadherins, Epithelial (E-) and Neural (N-) cadherin in reproductive biology. Its provides evidence of studies done by several research groups about the expression of E- and N-cadherin during spermatogenesis, oogenesis and folliculogenesis, and their involvement in gamete transport in the reproductive tracts. Moreover, it describes current knowledge of E- and N-cadherin presence in cells of the cumulus -oocyte complex and spermatozoa from several mammalian species, and shows gathered evidence on their participation in different steps of the fertilization process. A brief summary on general information of both proteins is also presented. [ABSTRACT FROM AUTHOR]

The life cycle of coral is affected by natural and anthropogenic perturbations occurring in the marine environment. In the context of global changes, it is likely that rainfall events will be more intense and that coastal reefs will be exposed to sudden drops in salinity. Therefore, a better understanding of how corals—especially during the pelagic life stages—are able to deal with declines in salinity is crucial. To fill this knowledge gap, this work investigated how gametes and larva stages of two species of Acropora ( Acropora cytherea and Acropora pulchra ) from French Polynesia cope with drops in salinity. An analysis of collected results highlights that both Acropora coral gametes displayed the same resistance to salinity changes, with 4h30-ES 50 (effective salinity that decrease by 50% the fertilization success after 4h30 exposure) of 26.6 ± 0.1 and 27.5 ± 0.3‰ for A. cytherea and A. pulchra , respectively. This study also revealed that coral gametes were more sensitive to decreases in salinity than larvae, for which significant changes are only observed at 26‰ for A. cytherea after 14 d of exposure. Although rising seawater temperatures and ocean acidification are often perceived as the main threat for the survival of coral reefs, our work indicates that 70% of the gametes could be killed during a single night of spawning by a rainfall event that decreases salinity to 26‰. This suggests that changes in the frequency and intensity of rainfall events associated with climate changes should be taken seriously in efforts to both preserve coral gametes and ensure the persistence and renewal of coral populations. [ABSTRACT FROM AUTHOR]

Despite investigative interest, the artificial derivation of pluripotent stem cells remains inefficient and incomplete reprogramming hinders its potential as a reliable tool in regenerative medicine. By contrast, fusion of terminally differentiated gametes at fertilization activates efficient epigenetic reprogramming to ensure totipotency of early embryos. Understanding the epigenetic mechanisms required for the transition from the fertilized egg to the embryo can improve efforts to reprogram differentiated cells to pluripotent/totipotent cells for therapeutic use. We review recent discoveries that are providing insight into the molecular mechanisms required for epigenetic reprogramming to totipotency in vivo . [ABSTRACT FROM AUTHOR]

Little is known about the molecular mechanisms that induce gamete fusion during mammalian fertilization. After initial contact, adhesion between gametes only leads to fusion in the presence of three membrane proteins that are necessary, but insufficient, for fusion: Izumo1 on sperm, its receptor Juno on egg and Cd9 on egg. What happens during this adhesion phase is a crucial issue. Here, we demonstrate that the intercellular adhesion that Izumo1 creates with Juno is conserved in mouse and human eggs. We show that, along with Izumo1, egg Cd9 concomitantly accumulates in the adhesion area. Without egg Cd9, the recruitment kinetics of Izumo1 are accelerated. Our results suggest that this process is conserved across species, as the adhesion partners, Izumo1 and its receptor, are interchangeable between mouse and human. Our findings suggest that Cd9 is a partner of Juno, and these discoveries allow us to propose a new model of the molecular mechanisms leading to gamete fusion, in which the adhesion-induced membrane organization assembles all key players of the fusion machinery. [ABSTRACT FROM AUTHOR]

With the advent of assisted reproductive technology in the past three decades, the clinical importance of fallopian tubes has been relatively overlooked. However, successful spontaneous conception requires normal function of the tube to provide not only a conduit for the gametes to convene and embryo to reach the uterine cavity, but also a physiologically optimized environment for fertilization and early embryonic development. In this review, after a brief description of normal human tubal anatomy and histology, we will discuss tubal transport and its principal effectors, including ciliary motion, muscular contractility and tubal fluid. Furthermore, we will discuss the ciliary ultrastructure and regulation of ciliary beat frequency by ovarian steroids, follicular fluid, angiotensin system, autonomic nervous system and other factors such as adrenomedullin and prostaglandins. In the last section, we describe the adverse impact of various pathological conditions, such as endometriosis, infection and smoking on tubal function and ciliary motility. [ABSTRACT FROM AUTHOR]

Most Old World mice and rats, subfamily Murinae, have a spermatozoon with an apical hook, a long tail and, as seen typically in eutherian mammals, a bilaterally flattened head. Dramatically different from this are the sperm of the Greater Bandicoot Rat, Bandicota indica. Here, we ask the question has the structure of the sperm head co-evolved with that of the egg coat, the zona pellucida? For this, we first summarise the morphological features of the spermatozoon of B. indica that may relate to zona pellucida penetration at the time of fertilisation, and we confirm that the sperm head is generally round, not bilaterally flattened, in profile and has a huge acrosome. We then show that the zona pellucida around oocytes in tertiary follicles also differs from that of the other murine rodents in being only about 4 μm thick and, as demonstrated by lectin staining, has an unusual abundance of alpha-L-fucose. These findings indicate that both the male and female gametes of this South-East Asian murine rodent are highly divergent in their structural organisation. One of the functional implications of this probably relates to sperm-zona interactions and the release of acrosomal enzymes that probably facilitate penetration by digestion of the zona matrix at the time of fertilisation. [ABSTRACT FROM AUTHOR]

Abstract: Since the Industrial Revolution, rising atmospheric CO2 concentration has driven an increase in the partial pressure of CO2 in seawater (pCO2), thus lowering ocean pH. We examined the separate effects of exposure of gametes to elevated pCO2 and low pH on fertilization success of the sea urchin Strongylocentrotus nudus. Sperm and eggs were independently exposed to seawater with pCO2 levels ranging from 380 (pH7.96–8.3) to 6000ppmv (pH7.15–7.20). When sperm were exposed, fertilization rate decreased drastically with increased pCO2, even at a concentration of 450ppmv (pH range: 7.94 to 7.96). Conversely, fertilization of Hemicentrotus pulcherrimus was not significantly changed even when sperm was exposed to pCO2 concentrations as high as 750ppmv. Exposure of S. nudus eggs to seawater with high pCO2 did not affect fertilization success, suggesting that the effect of increased pCO2 on sperm is responsible for reduced fertilization success. Surprisingly, this result was not related to sperm motility, which was insensitive to pCO2. When seawater was acidified using HCl, leaving pCO2 constant, fertilization success in S. nudus remained high (>80%) until pH decreased to 7.3. While further studies are required to elucidate the physiological mechanism by which elevated pCO2 impairs sperm and reduces S. nudus fertilization, this study suggests that in the foreseeable future, sea urchin survival may be threatened due to lower fertilization success driven by elevated pCO2 rather than by decreased pH in seawater. [Copyright &y& Elsevier]

Malaria parasite transmission requires the successful development of P lasmodium gametocytes into flagellated microgametes upon mosquito blood ingestion, and the subsequent fertilization of microgametes and macrogametes for the development of motile zygotes, called ookinetes, which invade and transverse the A nopheles vector mosquito midgut at around 18-36 h after blood ingestion. Within the mosquito midgut, the malaria parasite has to withstand the mosquito's innate immune response and the detrimental effect of its commensal bacterial flora. We have assessed the midgut colonization capacity of five gut bacterial isolates from field-derived, and two from laboratory colony, mosquitoes and their effect on P lasmodium development in vivo and in vitro, along with their impact on mosquito survival. Some bacterial isolates activated the mosquito's immune system, affected the mosquito's lifespan, and were capable of blocking P lasmodium development. We have also shown that the ability of these bacteria to inhibit the parasites is likely to involve different mechanisms and factors. A S erratia marcescens isolate was particularly efficient in colonizing the mosquitoes' gut, compromising mosquito survival and inhibiting both Plasmodium sexual- and asexual-stage through secreted factors, thereby rendering it a potential candidate for the development of a malaria transmission intervention strategy. [ABSTRACT FROM AUTHOR]

Background Neural tube defects (NTDs) are the second most common birth defect in humans. Dietary folic acid (FA) supplementation effectively and safely reduces the incidence of these often debilitating congenital anomalies. FA plays an established role in folate and homocysteine metabolism, but the means by which it suppresses occurrence of NTDs is not understood. In addition, many cases remain resistant to the beneficial effects of folic acid supplementation. To better understand the molecular, biochemical and developmental mechanisms by which FA exerts its effect on NTDs, characterized mouse models are needed that have a defined genetic basis and known response to dietary supplementation. Results We examined the effect of FA supplementation, at 5-fold the level in the control diet, on the NTD and vertebral phenotypes in Apobtm1Unc and Vangl2Lp mice, hereafter referred to as Apob and Lp respectively. The FA supplemented diet did not reduce the incidence or severity of NTDs in Apob or Lp mutant homozygotes or the loop-tail phenotype in Lp mutant heterozygotes, suggesting that mice with these mutant alleles are resistant to FA supplementation. Folic acid supplementation also did not affect the rate of resorptions or the size of litters, but instead skewed the embryonic genotype distribution in favor of wild-type alleles. Conclusion Similar genotypic biases have been reported for several NTD models, but were interpreted as diet-induced increases in the incidence and severity of NTDs that led to increased embryonic lethality. Absence of differences in resorption rates and litter sizes argue against induced embryonic lethality. We suggest an alternative interpretation, namely that FA supplementation led to strongly skewed allelic inheritance, perhaps from disturbances in polyamine metabolism that biases fertilization in favor of wild-type gametes. [ABSTRACT FROM AUTHOR]

Contents The oviduct has an important role in regulating transport of gametes and fertilization. The main role in these functions has a smooth muscle cells and ciliated epithelium lining the oviduct. All functions are under the influence of hormonal and nervous system. The objective of this study was immunohistochemically to examine the following structures: lining epithelium, smooth muscle cells, elastic fibres and nerve fibres. For this purpose, the following antibodies were used: cytokeratin 18, S-100 protein, acetylated α-tubulin, smooth muscle actin, desmin and elastin. Ciliary and secretory cells of the lining epithelium were positive for cytokeratin 18 and S-100 protein. Cilia and the basal body-associated structures of ciliary cells were positive to acetylated α-tubulin. Smooth muscle cells ( SMC) in mucosa and of the muscular layer were positive for α-smooth muscle actin ( SMA) and desmin. High density of nerve fibres positively reacted to acetylated α-tubulin and S100 protein was present in the mucosa, muscular layer and serosa. Elastic fibres positive for elastin form a dense network at the base of the mucosal folds and in the muscle layer. A dense network of these fibres is accompanying the blood vessels. It is supposed that together with smooth muscle cells they are involved in the transport of ovum and in blood flow regulation. [ABSTRACT FROM AUTHOR]

In this retrospective cohort study we intended to propose a classification and preliminary management strategy for couples exhibiting total fertilization failure (TFF) in intra-cytoplasmic sperm injection (ICSI) cycles. Sixteen couples with a total of 27 cycles exhibiting TFF, age <40 and/or more than four M2 oocytes aspirated were enrolled. While TFF occurred in 4.3% of all 3723 ICSI cycles, in women younger than 40 with at least 5 M2 oocytes the TFF rate was 0.7%. Indications for ICSI were severe male factor and unexplained infertility. Of the 16 couples with TFF, 4 demonstrated a single episode of TFF, with either subsequent or former normal fertilizations, thus implying possible sporadic faulty laboratory conditions. Ten couples demonstrated repeated total or very low fertilization rates, hinting at a gamete defect not overcome by ICSI. Two couples experienced TFF in the first and only cycle performed at our unit. We conclude that initial and repeated TFF hints at severe gamete defects for which only donor gametes may prove successful while sporadic TFF events could simply imply a technical modifiable condition. 在这项回顾性队列研究中，我们试图提出单精子卵细胞浆内注射周期完全受精失败夫妇的分类及初步管理策略。在本研究中，入组的16对夫妇一共发生了27个周期的完全受精失败，入组夫妇年龄均小于40岁，均取得了超过4个M2期卵母细胞。所有3723例单精子卵细胞胞浆内注射周期完全受精失败的发生率是4.3%，但在年龄小于40岁的妇女且至少取得5个M2期卵母细胞组的完全受精失败的发生率仅为0.7%。单精子胞浆内注射的指征是严重的男性不育因素及不明原因不孕。在发生完全受精失败的16对夫妇中，4对夫妇的完全受精失败是单次事件，她们随后的或者之前的周期中均有正常的受精，这提示是实验室条件改变的偶发失败；10对反复发作或者非常低受精率的夫妇提示了单精子胞浆内注射方法无法解决配子缺陷的问题；另外2对完全受精失败的夫妇在我们实验室有且只做了这一个周期。我们得出这样的结论：初始和重复的完全受精失败暗示严重的配子缺陷，捐赠配子可能是唯一的治疗策略。零星的完全受精失败事件可能只是意味着实验室条件的改变。 [ABSTRACT FROM AUTHOR]

Interspecies fertilization is rare, partly due to species separation enforced at the molecular level. In this issue, Raj et al. now reveal the crystal structures of mollusk egg coat protein, VERL, complexed with cognate sperm protein lysin. Given that VERL is structurally similar to mammalian ZP2, the mechanism elucidating species-specific gamete recognition likely exists in mammals. [ABSTRACT FROM AUTHOR]

Valuable aquaculture and fisheries industries for the North American geoduck, Panopea generosa, have driven interest in developing similar ventures for other geoduck species including P. zelandica from New Zealand. However, little is known about the fertilization kinetics of this species, or the conditions under which the amount and quality of larvae can be maximized. We determined the effects of sperm concentration, gamete age and contact time on the fertilization success of P. zelandica using an extended-Vogel-Czihak-Chang-Wolf ( EVCCW) model. The model provided a good fit to laboratory data when applied to individual contact times. For a contact time of 10 s, optimal fertilization was achieved at concentrations of approximately 104 sperm μL−1, but this decreased to as little as 102 sperm μL−1 for contact times of several minutes. Optimal fertilization was always <100% (max. observed 70%) and the proportion of fertilized eggs decreased rapidly at sperm concentrations above the optimal. According to the model this was due to a slow block to polyspermy. If commercial hatchery facilities ensure that broodstock are in ripe condition, and use sperm <30-min old, then optimal fertilization can be expected at sperm densities of 102-103 sperm μL−1 at contact times of 5-10 min. [ABSTRACT FROM AUTHOR]

Transgenerational phenotypic plasticity is increasingly recognized as an important buffer of environmental change - many studies show that mothers alter the phenotype of their offspring so as to maximize their performance in their local environment. Fewer studies have examined the capacity of parents to alter the phenotype of their gametes to cope with environmental change. In organisms that shed their gametes externally, gametes are extremely vulnerable to local stresses and transgenerational plasticity in the phenotypes of gametes seems likely in this group., In a marine tubeworm, Hydroides diramphus, we manipulated the salinity environment that mothers and fathers experienced before reproduction and then examined the phenotype of their gametes, as well as the performance of those gametes and the resultant larvae in different salinities., We found strong evidence for gamete plasticity - both mothers and fathers adaptively adjust the phenotype of their gametes to maximize the performance of those gametes in the salinity regime experienced by their parents. Parents were quite flexible in the phenotype of gametes that they produced: they could switch the salinity tolerance of their gametes back and forth depending on their most recent experience., Gamete plasticity was not without risks, however. We observed strong trade-offs in performance when gametes experienced an environment that did not match that of their parents. These effects of the parental environment persist for the duration of the larval phase such that larvae may not be able to disperse to environments that do not match their parents. Gamete plasticity may therefore represent an important source of phenotype-environment mismatches., Gamete plasticity may represent an important mechanism for coping with environmental change and an important source of maternal and paternal effects in species with external fertilization. Studies that seek to predict the impacts of stresses that persist across generations (e.g. ocean acidification) should include parental exposures to the stress of interest. [ABSTRACT FROM AUTHOR]