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SUMMARY Gametocidal (Gc) chromosomes have been widely utilized in genetic breeding due to their ability to induce chromosomal breakage and eliminate gametes that lack them. Long noncoding RNAs (lncRNAs) have various functional mechanisms in regulating pollen and anther development; however, their regulatory contributions to Gc action are still unknown. Here, we identified 2824 differentially expressed lncRNAs (DE‐lncRNAs) from the anther tissues of Triticum aestivum cv. Chinese Spring (CS) and Chinese Spring‐Gc 3C chromosome monosomic addition line (CS‐3C) through sequencing. In this study, we predicted 161 target mRNAs for 145 DE‐lncRNAs, including 104 cis‐regulatory, 60 trans‐regulatory, and three both cis‐regulatory and trans‐regulatory manner. Combined with our previous miRNA sequencing data, 241 DE‐lncRNAs functioned as potential endogenous target mimics (eTMs) for 84 differentially expressed microRNAs (DE‐miRNAs, including 12 novel miRNAs). The results of transient transformation in tobacco leaves indicated that L006278 could bind to MTCONS_00006277, which encoded a calcineurin CBL‐interacting protein kinase 19‐like, and suppress its expression. Furthermore, L117735 could function as an eTM for tae‐miR9657b‐3p, and L056972 could function as an eTM for gc‐m2240‐5p. To explore the function of lncRNAs in the process of Gc action, we transformed L006278, an up‐regulated lncRNA in CS‐3C, into rice to analyze its effect on pollen fertility. Overexpression of L006278 led to a reduction in rice pollen fertility. Overall, our findings indicate that lncRNAs can contribute to the regulation of pollen fertility during the process of Gc action by regulating the expression levels of target mRNAs and acting as eTMs for certain key miRNAs. [ABSTRACT FROM AUTHOR]

ABSTRACT Pollen development and germination are critical for successful generation of offspring in plants, yet they are highly susceptible to heat stress (HS). However, the molecular mechanism underlying this process has not been fully elucidated. In this study, we highlight the essential roles of two mRNA capping enzymes, named Arabidopsis mRNA capping phosphatase (ARCP) 1 and 2, in regulating male and female gamete development. The transmission efficiencies of gametes carrying arcp1 arcp2 from arcp1+/− arcp2−/− and arcp1−/− arcp2+/− mutants are 30% and zero, respectively. These mutants exhibited a significant increase in misshaped pollen, with germination rates approximately half of those in wild type. ARCP1/2 exhibit RNA triphosphatase and RNA guanylyltransferase activities, which are required for proper pollen development. Through RNA‐seq analysis, genes involved in pollen development/germination and HS response were identified as downregulated genes in pollen from arcp1+/− arcp2−/− mutant. Furthermore, ARCP2 protein is degraded under HS condition, and inducing the expression of ARCP2 can increase the pollen germination rate under elevated temperature. We propose that HS triggers the degradation of mRNA capping enzymes, which in turn disrupts the transcriptome that required for pollen development and pollen germination and ultimately leads to male sterility. [ABSTRACT FROM AUTHOR]

Nanotechnology and its applications have advanced significantly in recent decades, contributing to various fields, including reproduction. This study introduces a novel method to label porcine oocytes with nanoparticles (NPs) bound to oviductin (OVGP1, Ov) for use in Assisted Reproductive Technologies (ARTs). Despite promising developments, concerns about NP toxicity in gametes necessitate thorough investigation. This research aims to assess the impact of functionalized NPs (NPOv) on sperm functionality. Boar sperm were co‐incubated with NPOv for 0, 0.5 and 1 h in two media: BTS (semen dilution and conservation) and TALP (sperm capacitation and in vitro fertilization‐IVF). Sperm quality parameters (viability, motility and kinematics) showed no significant differences in TALP medium (p >.05). In BTS, although some kinetic parameters were altered, motility, progressive motility and viability remained unaffected (p >.05). Additionally, NPs presence on the zona pellucida (ZP) of oocytes did not affect sperm attachment (p >.05). In conclusion, in vitro exposure of boar sperm to OVGP1‐functionalized NPs in IVF medium or attached to the ZP surface of matured oocytes does not impair sperm functionality, including their binding ability to the ZP. [ABSTRACT FROM AUTHOR]

With the continued expansion and commercialisation of fertility treatments, the selection and matching of donors have become more sophisticated and technologised. As part of this landscape, new form of genetic screening: ‘expanded carrier screening’ (ECS) is being offered as a technique to avoid the risk of donors passing on genetic conditions to future offspring. Allowing donors to be tested for hundreds of genetic conditions simultaneously, ECS marks a considerable departure from traditional ‘family history’ models of screening, which rely on an individual's knowledge of family health. There is growing evidence of a drive towards the use of ECS within the fertility sector, and a growing number of clinics are offering it for a fee, as part of an egg or sperm donation cycle or as an add‐on to IVF treatment. In this article, we use methods of critical reflection to synthesise data from two studies to explore how ECS is being used to avoid genetic risk in IVF treatment using donor gametes. We suggest that ECS is a new form of repro‐genetic selection—a selective reproductive technology—with specific and important implications for donors, recipients and clinicians and with the potential to reconfigure the scope and application of gamete donation. We examine these implications and conclude that the existing policy blind spot relating to this development in fertility treatment practice needs to be urgently addressed. [ABSTRACT FROM AUTHOR]

ABSTRACT There is much dispute about what we owe the children we are responsible for creating. Some argue that so long as we provide offspring with lives worth living we do no wrong. Others argue that our procreative obligations are weightier and oblige us to provide (or attempt to provide) our offspring with a reasonable opportunity to thrive, or meet some other standard beyond merely providing a life worth living. Our practices and intuitions on this matter are inconsistent. For example, gamete donors who intentionally participate in the project of creating a child are thought to have few obligations to their offspring, but those who create a child accidentally are thought to have weighty obligations. Furthermore, a justification for why we are obliged to provide offspring with more than a life worth living has been elusive. To resolve this puzzle I argue that an under‐theorized element of morality, the directed duty of care, explains why we owe our offspring more than a life worth living. [ABSTRACT FROM AUTHOR]

Parental care is essential to offspring survival in many species. Understanding why males of some species provide care, whereas others do not, has received substantial attention. Previous research has found that sexual selection can favor paternal care, yet we still do not fully understand why sexual selection favors male care in some species but not others. It is also unclear when paternal care versus other preferred male trait(s) will be favored by sexual selection. We hypothesize that sexual selection can interact with basic life history to influence the conditions under which paternal care and/or another preferred male trait will be favored by sexual selection. We used a mathematical approach in which males alone provide parental care and exhibit a non‐care trait that is preferred in mate choice. Using this approach, we demonstrate that life‐history characteristics (stage‐specific mortality, fertilization success, gamete numbers) can interact with sexual selection to influence the evolution of paternal care and/or a preferred non‐care trait. In particular, whether (1) adult mortality, egg mortality, and fertilization success are high versus low and (2) a tradeoff exists between paternal care and a non‐care preferred trait will influence whether selection most strongly favors additional paternal care or a non‐care preferred trait. In general, we would expect strong selection for more male care when it is preferred in mate choice. In some cases, mate preferences for paternal care can inhibit selection for a preferred non‐care trait. Mate preferences for paternal care can also broaden the life‐history conditions under which we would expect the elaboration of male care to occur. [ABSTRACT FROM AUTHOR]

Premise: Quaking aspen is a clonal tree species that has mixed ploidy, often with high relative abundance of both diploids and triploids but no haploids or tetraploids. Triploids typically have low fertility, leaving their occurrence apparently unlikely from an evolutionary perspective, unless they provide a "triploid bridge" to generating higher‐fitness tetraploids—which are not observed in this species. This study focused on how triploidy can be maintained in quaking aspen. Methods: A computational model was used to simulate gamete production, sexual reproduction, asexual reproduction, parent survival, and offspring survival in a population. All parameters were assumed to be cytotype‐dependent and environment‐independent. Sampling methods were used to identify parameter combinations consistent with observed cytotype frequencies. Results: Many processes and parameter values were sufficient to yield a moderate frequency of triploids, and very few were necessary. The most plausible route involved higher triploid survival at the parent or offspring stage and limited unreduced gamete production by either diploid or triploid parents. Triploid fertility was helpful but not necessary. Conclusions: The coexistence of diploids and triploids in quaking aspen is statistically likely and promoted by the existence of commonly observed, long‐lived triploid clones. However, other mechanisms not captured by the model related to environmental variation could also occur. Further empirical data or more complex but difficult‐to‐parameterize models are needed to gain further insight. [ABSTRACT FROM AUTHOR]

The commercial viability of walleye (Sander vitreus) as an aquaculture species requires that walleye gametes are available year‐round so that multiple cohorts of walleye can be brought to market throughout the year. This study aimed to apply photothermal manipulations to three groups of walleye broodstock to induce out‐of‐season spawning and obtain a year‐round supply of fertilized walleye eggs. We manipulated photothermal regimes for three groups of broodstock to induce spawning in February (early), April (in‐season), and July (late‐season). In autumn, water temperatures were chilled to 8°C in all treatments. The duration of the chill period varied for each treatment with the early, in‐season, and late treatments remaining chilled for 6, 18, and 30 weeks, respectively, before being warmed to induce spawning. Fecundity was significantly lower for late‐season broodstock. Egg size and gonadosomatic index were significantly smaller in the early‐season treatment. Fertilization success was similar for early and in‐season treatments but was 0% for eggs from the late‐season treatment. Larval survival was significantly lower for walleye from early‐season broodstock. Our results suggest that early out‐of‐season spawning for walleye is possible but comes with tradeoffs of smaller egg size and lower larval survival. [ABSTRACT FROM AUTHOR]

An astonishing range of morphologies and life strategies has arisen across the vast diversity of protists, allowing them to thrive in most environments. In model protists, like Tetrahymena, Dictyostelium, or Trypanosoma, life cycles involving multiple life stages with different morphologies have been well characterized. In contrast, knowledge of the life cycles of free‐living protists, which primarily consist of uncultivated environmental lineages, remains largely fragmentary. Various life stages and lineage‐specific cellular innovations have been observed in the field for uncultivated protists, but such innovations generally lack functional characterization and have unknown physiological and ecological roles. In the actual state of knowledge, evidence of sexual processes is confirmed for 20% of free‐living protist lineages. Nevertheless, at the onset of eukaryotic diversification, common molecular trends emerged to promote genetic recombination, establishing sex as an inherent feature of protists. Here, we review protist life cycles from the viewpoint of life cycle transitions and genetics across major eukaryotic lineages. We focus on the scarcely observed sexual cycle of free‐living protists, summarizing evidence for its existence and describing key genes governing its progression, as well as, current methods for studying the genetics of sexual cycles in both cultivable and uncultivated protist groups. [ABSTRACT FROM AUTHOR]

Germline regulates the expression of life‐history traits and mediates the trade‐off between reproduction and somatic maintenance. However, germline maintenance in itself can be costly, and the costs can vary between the sexes depending on the number of gametes produced across the lifetime. We tested this directly by germline ablation using glp‐1 RNA interference (RNAi) in a dioecious nematode Caenorhabditis remanei. Germline removal strongly increased heat‐shock resistance in both sexes, thus confirming the role of the germline in regulating somatic maintenance. However, germline removal resulted in increased lifespan only in males. High costs of mating strongly reduced lifespan in both sexes and obliterated the survival benefit of germline‐less males even though neither sex produced any offspring. Furthermore, germline removal reduced male growth before maturation but not in adulthood, while female growth rate was reduced both before and especially after maturation. Thus, germline removal improves male lifespan without major growth costs, while germline‐less females grow slower and do not live longer than reproductively functional counterparts in the absence of environmental stress. Overall, these results suggest that germline maintenance is costlier for males than for females in C. remanei. [ABSTRACT FROM AUTHOR]

Gamete traits can vary widely among species, populations and individuals, influencing fertilisation dynamics and overall reproductive fitness. Sexual selection can play an important role in determining the evolution of gamete traits with local environmental conditions determining the strength and direction of sexual selection. Here, we test for signatures of post‐mating selection on gamete traits in relation to population density, and possible interactive effects of population density and sperm concentration on sperm motility and fertilisation rates among natural populations of mussels. Our study shows that males from high‐density populations produce smaller sperm compared with males from low‐density populations, but we detected no effect of population density on egg size. Our results also reveal that females from low‐density populations tended to exhibit lower fertilisation rates across a range of sperm concentrations, although this became less important as sperm concentration increased. Variances in fertilisation success were higher for females than males and the effect of gamete compatibility between males and females increases as sperm concentrations increase. These results suggest that local population density can influence gamete traits and fertilisation dynamics but also highlight the importance of phenotypic plasticity in governing sperm–egg interactions in a highly dynamic selective environment. [ABSTRACT FROM AUTHOR]

The developmental origins of health and disease (DOHaD) shows that a relationship exists between parental environment at large, foeto‐placental development and the risk for the offspring to develop non‐transmittable disease(s) in adulthood. This concept has been validated in both humans and livestock. In mammals, after fertilization and time spent free in the maternal reproductive tract, the embryo develops a placenta that, in close relationship with maternal endometrium, is the organ responsible for exchanges between dam and foetus. Any modification of the maternal environment can lead to adaptive mechanisms affecting placental morphology, blood flow, foetal‐maternal exchanges (transporters) and/or endocrine function, ultimately modifying placental efficiency. Among deleterious environments, undernutrition, protein restriction, overnutrition, micronutrient deficiencies and food contaminants can be outlined. When placental adaptive capacities become insufficient, foetal growth and organ formation is no longer optimal, including foetal gonadal formation and maturation, which can affect subsequent offspring fertility. Since epigenetic mechanisms have been shown to be key to foetal programming, epigenetic modifications of the gametes may also occur, leading to inter‐generational effects. After briefly describing normal gonadal development in domestic species and inter‐species differences, this review highlights the current knowledge on intra‐uterine programming of offspring fertility with a focus on domestic animals and underlines the importance to assess transgenerational effects on offspring fertility at a time when new breeding systems are developed to face the current climate changes. [ABSTRACT FROM AUTHOR]

Brown algal male gametes show chemotaxis to the sex pheromone that is released from female gametes. The chemotactic behavior of the male gametes is controlled by the changes in the beating of two flagella known as the anterior and posterior flagellum. Our previous study using Mutimo cylindricus showed that the sex pheromone induced an increment in both the deflection angle of the anterior flagellum and sustained unilateral bend of the posterior flagellum, but the mechanisms regulating these two flagellar waveforms were not fully revealed. In this study, we analyzed the changes in swimming path and flagellar waveforms with a high‐speed recording system under different calcium conditions. The extracellular Ca2+ concentration at 10−3 M caused an increment in the deflection angle of the anterior flagellum only when ionomycin was absent. No sustained unilateral bend of the posterior flagellum was induced either in the absence or presence of ionomycin in extracellular Ca2+ concentrations below 10−2 M. Real‐time Ca2+ imaging revealed that there is a spot near the basal part of anterior flagellum showing higher Ca2+ than in the other parts of the cell. The intensity of the spot slightly decreased when male gametes were treated with the sex pheromone. These results suggest that Ca2+‐dependent changes in the anterior and posterior flagellum are regulated by distinct mechanisms and that the increase in the anterior flagellar deflection angle and sustained unilateral bend of the posterior flagellum may not be primarily induced by the Ca2+ concentration. [ABSTRACT FROM AUTHOR]

Heterospecific interactions are an important phenomenon of animal epigamic behaviour; however, they remain understudied within important groups, such as insects. Dragonflies are an ideal group for research on interspecific mating and possible hybridisation as they are easily identifiable, large insects, with a conspicuous mating process, often striking territorial behaviour and several mating systems.Using the genus Sympetrum as the model group, we examined heterospecific mating at three different levels. In the field, we identified whether species identity, time and weather affected heterospecific mating frequency. One important part of heterospecific mating is whether the process is completed. For dragonflies, this means that flying in tandem is followed by successful copulation, gamete fusion and oviposition (which comprise mating completeness). In a mesocosm experiment, we determined mating completeness (tandems, copulation, oviposition) of hetero‐ and homospecific pairs and the possible role of species density in heterospecific mating. In the laboratory, we compared the viability of the offspring from heterospecific pairs with different epigamous behaviour.We found heterospecific mating to be a relatively common phenomenon unaffected by environmental variables, that was primarily influenced by species identity, temporal distribution and abundance of dragonfly species. Consequently, the presence of counterparts of other species is the main predictor of the frequency of heterospecific mating.The probability of completed epigamic behaviour (copulation and subsequent oviposition) connected with gamete fusion is lower in heterospecific mating. Generally, based on our results we can assume that successful heterospecific mating (leading to gamete fusion) occurs in closely related species (e.g., Sympetrum striolatum and Sympetrum vulgatum). However, as pre‐copulatory barriers are not strongly developed in some dragonfly groups, less closely related species (e.g., Sympetrum sanguineum and S. striolatum) also may mate. This phenomenon requires further study as it may present a threat to the survival of some species in the context of changing environmental conditions, including climate change. [ABSTRACT FROM AUTHOR]

At the heart of the use of assisted reproductive technologies (ARTs) is the attempt to realise a commonly anticipated future – the opportunity, if desired, to create and raise a genetically related child. For some, existing ARTs cannot assist, yet upcoming ones such as in vitro derived gametes (IVGs) may do so. However, the desire for genetically related children is frequently critiqued in debates about new ARTs. Since most heterosexual couples can have such children without assistance, and same‐sex couples are equally likely to desire them, this is highly problematic. This article presents the moral and legal case for the legalisation of IVGs, if and when judged sufficiently safe. It analyses development of the concept of 'treatment' in relevant UK law; argues that it is reasonable (that is, not unreasonable) to value the project of procreative parenting, thereby refuting the arguments that there is a moral duty to adopt, or that the alternatives of adoption or donor conception should suffice; explores legal recognition of the ordinary place of reproduction in social life; and considers the implications of the rights to private and family life and to non‐discrimination, particularly under the European Convention on Human Rights, highlighting the disabling nature of infertility. [ABSTRACT FROM AUTHOR]

Summary: In planta haploid induction (HI), which reduces the chromosome number in the progeny after fertilization, has garnered increasing attention for its significant potential in crop breeding and genetic research. Despite the identification of several natural and synthetic HI systems in different plant species, the molecular and cellular mechanisms underlying these HI systems remain largely unknown. This review synthesizes the current understanding of HI systems in plants (with a focus on genes and molecular mechanisms involved), including the molecular and cellular interactions which orchestrate the HI process. As most HI systems can function across taxonomic boundaries, we particularly discuss the evidence for conserved mechanisms underlying the process. These include mechanisms involved in preserving chromosomal integrity, centromere function, gamete communication and/or fusion, and maintenance of karyogamy. While significant discoveries and advances on haploid inducer systems have arisen over the past decades, we underscore gaps in understanding and deliberate on directions for further research for a more comprehensive understanding of in vivo HI processes in plants. [ABSTRACT FROM AUTHOR]

Summary: Combining two or more related homoeologous genomes in a single nucleus, newly formed allopolyploids must rapidly adapt meiosis to restore balanced chromosome segregation, production of euploid gametes and fertility. The poor fertility of such neo‐allopolyploids thus strongly selects for the limitation or avoidance of genetic crossover formation between homoeologous chromosomes.In this study, we have reproduced the interspecific hybridization between Arabidopsis thaliana and Arabidopsis arenosa leading to the allotetraploid Arabidopsis suecica and have characterized the first allopolyploid meioses.First‐generation neo‐allopolyploid siblings vary considerably in fertility, meiotic behavior and levels of homoeologous recombination. We show that centromere dynamics at early meiosis is altered in synthetic neo‐allopolyploids compared with evolved A. suecica, with a significant increase in homoeologous centromere interactions at zygotene. At metaphase I, the presence of multivalents involving homoeologous chromosomes confirms that homoeologous recombination occurs in the first‐generation synthetic allopolyploid plants and this is associated with a significant reduction in homologous recombination, compared to evolved A. suecica.Together, these data strongly suggest that the fidelity of recombination partner choice, likely during the DNA invasion step, is strongly impaired during the first meiosis of neo‐allopolyploids and requires subsequent adaptation. [ABSTRACT FROM AUTHOR]

The absence of robust interspecific isolation barriers among pantherines, including the iconic South American jaguar (Panthera onca), led us to study molecular evolution of typically rapidly evolving reproductive proteins within this subfamily and related groups. In this study, we delved into the evolutionary forces acting on the zona pellucida (ZP) gamete interaction protein family and the sperm‐oocyte fusion protein pair IZUMO1‐JUNO across the Carnivora order, distinguishing between Caniformia and Feliformia suborders and anticipating few significant diversifying changes in the Pantherinae subfamily. A chromosome‐resolved jaguar genome assembly facilitated coding sequences, enabling the reconstruction of protein evolutionary histories. Examining sequence variability across more than 30 Carnivora species revealed that Feliformia exhibited significantly lower diversity compared to its sister taxa, Caniformia. Molecular evolution analyses of ZP2 and ZP3, subunits directly involved in sperm‐recognition, unveiled diversifying positive selection in Feliformia, Caniformia and Pantherinae, although no significant changes were linked to sperm binding. Structural cross‐linking ZP subunits, ZP4 and ZP1 exhibited lower levels or complete absence of positive selection. Notably, the fusion protein IZUMO1 displayed prominent positive selection signatures and sites in basal lineages of both Caniformia and Feliformia, extending along the Caniformia subtree but absent in Pantherinae. Conversely, JUNO did not exhibit any positive selection signatures across tested lineages and clades. Eight Caniformia‐specific positive selected sites in IZUMO1 were detected within two JUNO‐interaction clusters. Our findings provide for the first time insights into the evolutionary trajectories of ZP proteins and the IZUMO1‐JUNO gamete interaction pair within the Carnivora order. [ABSTRACT FROM AUTHOR]

SUMMARY: The spatial arrangement of cell fusion sites and eyespots of the gametes in vis‐à‐vis mating pairs of Chlamydomonas eugametos, corresponding to the swimming zygote of Chlamydomonas reinhardtii, were studied using field emission scanning electron microscopy and light microscopy, respectively. After the adhesion of mt+ and mt− gametes, each of which has one eyespot and two flagella elongated from the cell anterior, gamete–gamete fusion occurred at the anterior papilla on the cell apex of each gamete, leading to the formation of a vis‐à‐vis mating pair, indicating that the cell fusion site is arranged symmetrically relative to the flagellar beat plane. In vis‐à‐vis mating pairs, two eyespots could be seen on the same or on opposite sides of the cell. As only the mt+ flagella and eyespot are functional for swimming and phototaxis in the vis‐à‐vis mating pair of C. eugametos, it is suggested that coordinated alignment of the parental gamete flagella and eyespots in the swimming zygote and asymmetric positioning of the gamete mating structure/cell fusion sites, which is prevalent in C. reinhardtii and other chlorophytes, is not necessary for C. eugametos. [ABSTRACT FROM AUTHOR]

Premise: Unreduced gametes are the primary mechanism of neopolyploid formation. Their production in diploid populations is arguably maladaptive, but the magnitude and patterns of genetically based variation maintained in natural populations are poorly understood. Methods: We examined variation in male and female unreduced gamete production among plants from different elevations in fireweed, Chamerion angustifolium, grown in a common environment. Using seeds from three high‐elevation and three low‐elevation diploid populations in one study, and a single diploid population in another, we estimated realized rates of unreduced male (sperm) and female (egg) gamete production by reciprocally pollinating diploid and tetraploid plants and estimating the incidence of tetraploid seeds using flow cytometry. Results: Unreduced gamete frequencies per plant were similar in the two studies (0.12% vs. 0.08%). High‐elevation populations had a greater percentage of fruit with seeds from unreduced gametes, but a lower percentage of seeds per fruit than low‐elevation populations. Female unreduced gamete frequencies differed among elevations, but male frequencies did not, and the gamete sexes were not correlated at the plant level. Conclusions: We conclude that genetically based variation for unreduced gametes is maintained within and among natural populations, despite their fitness disadvantages, suggesting that local selection may be ineffective at purging them under some conditions. [ABSTRACT FROM AUTHOR]

Maternal transfer of selenium (Se) to developing fish eggs during vitellogenesis can cause larval deformity and mortality. Previous studies have shown wide variation among fish species in both the magnitude of maternal transfer (exposure) and the egg Se concentration causing effects (sensitivity). We studied maternal transfer and effects of Se on early life stage development, survival, and growth of redside shiner (Richardsonius balteatus), a small‐bodied cyprinid that has been reported to have relatively high ovary:muscle Se concentration ratios. Gametes were collected from lentic areas in southeast British Columbia (Canada) with a range of dietary Se concentrations related to weathering of waste rock from coal mining. Eggs were fertilized and reared in the laboratory from hatch to the onset of exogenous feeding. Larvae were assessed for survival, length, weight, Se‐characteristic deformities, and edema. Eggs from a total of 56 females were collected, with egg Se concentrations from 0.7 to 28 mg/kg dry weight. Maternal transfer varied among sites, with egg:muscle Se concentration ratios ranging from <1 to >4. We also found that sampling residual ovaries can overestimate Se concentrations in ripe eggs by up to a factor of 5.7. A correlation between larval weight and egg Se concentration was identified, although the relationship was weak (r2 < 0.1) and appeared to be a site effect. No other relationships were observed between larval endpoints and egg Se concentrations up to the highest concentration tested, indicating that the effects threshold for this species may be >28 mg/kg dry weight in eggs. These data indicate that redside shiner is less sensitive to maternally transferred Se than most other tested fish species. Environ Toxicol Chem 2023;42:2350–2357. © 2023 SETAC [ABSTRACT FROM AUTHOR]

To our knowledge, there have been few discussions in the andrology literature regarding the ethics of disclosure to donor conceived children. Our goal in this paper is to summarize the main reasons in favor of disclosure to engender more conversations about the ethics of donor conception in andrology circles. Specifically, we argue (1) transparency regarding gamete donation upholds the ethical principle of beneficence by improving the psychological health of donor conceived children; and (2) based on the ethical principle of autonomy, donor conceived children should have the right to know their donor status. [ABSTRACT FROM AUTHOR]

Objective: The production of echinoid larvae and juveniles is required in both wild‐population enhancement programs and full life‐cycle culture. Many echinoid species of commercial interest spawn only once or twice a year, however, restricting temporal access to viable broodstock. High‐energy/high‐protein formulated feeds have been used for gonad enhancement of a variety of echinoid species, but the goal of that activity has always been to produce premature gonads, which the market requires, not the production of mature gonads for breeding. The present investigation, originally established to examine gonad enhancement, took advantage of a spawning event to assess the efficacy of a formulated feed to extend the spawning period or reduce gonad recovery time after spawning in a commercially relevant echinoid, the green sea urchin Strongylocentrous droebachiensis. Methods: Urchins held in suspended sea cages were fed either a formulated, commercial, pelleted urchin diet or bull kelp Nereocystis luetkeana over 12 weeks, with survival, somatic growth, gonad quantity (wet weight, yield), and gonad quality (presence/absence of gametes) being examined over time. Result: Survivorship after 12 weeks was high, little difference being observed between the two diets (mean ± SE: 98.2 ± 1.1% and 95.9 ± 1.9% for kelp and formulated feed, respectively). There was no significant difference in somatic growth between the two treatments, but the formulated feed led to significantly higher gonad wet weight and yield than kelp at the end of the study. When compared with kelp, the formulated feed may have led to earlier spawning and quicker gonad recovery and prevented the complete spawning of all urchins, thus extending the period of gamete availability. Conclusion: Formulated feeds may have the potential to maintain reproductively active broodstock over an extended time, allowing expansion of the period in which echinoid larvae and juveniles can be produced. Impact statementFormulated feeds may have the potential to maintain reproductively active urchin broodstock over an extended time, allowing expansion of the period in which urchin larvae and juveniles can be produced by urchin farmers. [ABSTRACT FROM AUTHOR]

Understanding the fitness consequences of thermal history is necessary to predict organismal responses to global warming. This is especially challenging for ectotherms with complex life cycles, where distinct life stages can differ in thermal sensitivity, acclimate to different thermal environments and accrue responses to acclimation within and between generations.Although acclimation is often hypothesized to benefit organisms by helping them (or their offspring) to compensate for negative impacts of environmental change, mixed support for this hypothesis highlights the need to assess alternatives. Assessments that explicitly dissect responses across life stages and generations, however, remain limited.We assess alternative hypotheses of acclimation (none, beneficial, colder‐is‐better and warmer‐is‐better) within and between generations of a marine tubeworm whose vulnerability to warming rests on survival at early planktonic stages (gametes, embryos and larvae). First, we acclimate parents, gametes and embryos to ambient and projected warmer temperatures (17°C and 22°C) factorially by life stage. Next, we rear offspring with differing acclimation histories to the end of larval development at test temperatures from 10°C to 28°C (lower and upper survival limits respectively). Last, we estimate thermal survival curves for development, and compare them among thermal histories.We show that survival curves are most responsive to parental acclimation followed by acclimation at embryogenesis, but are buffered against acclimation at fertilization. Moreover, curves respond independently to acclimation within and between generations, and respond largely as predicted by the warmer‐is‐better hypothesis, despite the semblance of beneficial acclimation after successive doses of warmer temperature.Our study demonstrates the varied nature of thermal acclimation and the importance of considering how responses aggregate across complex life cycles when predicting vulnerability to warming. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Primordial germ cells (PGCs), are the source of gametes in vertebrates. There are similarities in the development of PGCs of reptiles with avian and mammalian species PGCs development. PGCs culture has been performed for avian and mammalian species but there is no report for reptilian PGCs culture. In vitro culture of PGCs is needed to produce transgenic animals, preservation of endangered animals and for studies on cell behaviour and research on fertility. Reptiles are traded as exotic pets and a source of food and they are valuable for their skin and they are useful as model for medical research. Transgenic reptile has been suggested to be useful for pet industry and medical research. In this research different aspects of PGCs development was compared in three main classes of vertebrates including mammalian, avian and reptilian species. It is proposed that a discussion on similarities between reptilian PGCs development with avian and mammalian species helps to find clues for studies of reptilian PGCs development details and finding an efficient protocol for in vitro culture of reptilian PG. [ABSTRACT FROM AUTHOR]

Metabolomics, an emerging omics technology developed in the post‐gene age, is an important part of systems biology. It interprets the pathophysiological state of the subject by quantitatively describing the dynamic changes of metabolites through analytical methods, mainly mass spectrometry (MS) and nuclear magnetic resonance (NMR). Assisted reproductive technology (ART) is a method used to manipulate sperm, oocytes, and embryos to achieve conception. Recently, several studies have reported that metabolomics methods can be used to measure metabolites in ART samples; these metabolites can be used to evaluate the quality of gametes and embryos. This article reviews the progress of research on metabolomics and the application of this technology in the field of ART, thus providing a reference for research and development directions in the future. [ABSTRACT FROM AUTHOR]

Sexual reproduction data are important to understand how organisms can replenish their populations and proliferate on coral reefs. Despite the importance of such data, the reproductive characteristics of most soft coral species are still unknown. Here, we examined the reproductive strategies of a species from the often‐dominant genus Sclerophytum in a coral reef on subtropical Okinawa Island, Japan. DNA barcoding and histological examinations of the tissues were conducted to confirm colony conspecificity and identify reproductive characteristics, respectively, between March 2020 and March 2021. Results indicated that the studied species, identified as Sclerophytum cf. heterospiculatum, exhibits gonochorism with longer oogenesis and shorter spermatogenesis. Female colonies produced immature oocytes throughout the year, with mature oocytes observed from late July to early September, and thus, extended spawning is likely characteristic of this species. In male colonies, spermatogenesis took place over ~5 months, with spermaries present from April through August. Mature spermaries were noted beginning in July and the inferred peak of sperm release was between late August and early September, which suggests that spermatogenesis duration was ~5 months. The largest mean oocyte and spermary sizes (628.45 ± 61.36 and 240.04 ± 49.49 μm, respectively) were both recorded in August. Gamete spawning presumably occurred during the summer season, which suggests seasonality in reproduction as influenced by changes in seawater temperature. However, the proximate cue for exact dates of spawning could be the lunar period because the inferred release of spawning materials seemed to occur between full moon and last‐quarter moon phases in both the months of August and September. The results of this study represent the first detailed report of reproductive characteristics of the genus Sclerophytum in Japan. [ABSTRACT FROM AUTHOR]

Xenogenesis is an innovative tool for hybrid catfish (female Channel Catfish Ictalurus punctatus × male Blue Catfish I. furcatus) seed production, accomplished by transplanting undifferentiated germ cells derived from a donor diploid fish into a sterile recipient, which then enables recipient fish to produce donor‐derived gametes. There is potential to collect donor‐derived germ cells from mature fish during certain times of the year depending upon seasonal temperature and serum sex steroid hormonal fluctuations. The objective of this study was to evaluate seasonal variations in germ cell counts and serum sex steroid hormonal profiles in mature Blue Catfish. Mature fish were collected monthly over the full annual cycle to quantify the number of live germ cells (spermatogonia A, oogonia), viability of germ cells, and levels of serum sex steroid hormones, including testosterone, 11‐ketotestosterone, and 17β estradiol. Extracted spermatogonia A counts were highest from April to June, whereas a significant decline was detected from July to November. Extracted live oogonia counts were highest in April and gradually decreased to zero over the months of May to August. Seasonal variations in serum testosterone, 11‐ketotestosterone, and 17β estradiol followed a similar pattern as the live spermatogonia A and oogonia counts. Even though spermatogonia A counts were relatively lower in mature than in immature Blue Catfish males, extracting spermatogonia A from mature Blue Catfish males during April to June provides an added advantage to the process of artificial fertilization, as it is required to sacrifice these fish to collect sperm. [ABSTRACT FROM AUTHOR]

Summary: The Closterium peracerosum–strigosum–littorale complex (Closterium, Zygnematophyceae) has an isogamous mating system. Members of the Zygnematophyceae are the closest relatives to extant land plants and are distantly related to chlorophytic models, for which a genetic basis of mating type (MT) determination has been reported. We thus investigated MT determination in Closterium.We sequenced genomes representing the two MTs, mt+ and mt−, in Closterium and identified CpMinus1, a gene linked to the mt− phenotype. We analyzed its function using reverse genetics methods.CpMinus1 encodes a divergent RWP‐RK domain‐containing‐like transcription factor and is specifically expressed during gamete differentiation. Introduction of CpMinus1 into an mt+ strain was sufficient to convert it to a phenotypically mt− strain, while CpMinus1‐knockout mt− strains were phenotypically mt+.We propose that CpMinus1 is the major MT determinant that acts by evoking the mt− phenotype and suppressing the mt+ phenotype in heterothallic Closterium. CpMinus1 likely evolved independently in the Zygnematophyceae lineage, which lost an egg–sperm anisogamous mating system. mt− specific regions possibly constitute an MT locus flanked by common sequences that undergo some recombination. [ABSTRACT FROM AUTHOR]

Do egg cell-secreted aspartic proteases promote gamete attachment? Considering that unfertilized egg cells will promote polytubey, additional pollen tubes carrying I hap2 i -sperm cells will enter the embryo sac and after sperm cell release, more I hap2 i -sperm cell pairs will attach to egg cells. Notably, [6] observed that sperm cells remained outside of the unfertilized egg cells at 30 hap, and unfused sperm cells were found detachable at 24 hap from egg cells of the I ecs1-1 ecs2-1 i mutant. This is the case for animal proteases located in cortical granules of oocytes ([4]) and for ECS1/2, which are stored in a cortical network at the chalazal pole of the egg cell before fertilization and secreted only upon successful sperm cell-egg cell fusion ([19]). [Extracted from the article]

Summary: Faithful meiotic progression ensures the generation of viable gametes. Studies suggested the male meiosis of plants is sensitive to ambient temperature, but the underlying molecular mechanisms remain elusive.Here, we characterized a maize (Zea mays ssp. mays L.) dominant male sterile mutant Mei025, in which the meiotic process of pollen mother cells (PMCs) was arrested after pachytene.An Asp‐to‐Asn replacement at position 276 of INVERTASE ALKALINE NEUTRAL 6 (INVAN6), a cytosolic invertase (CIN) that predominantly exists in PMCs and specifically hydrolyses sucrose, was revealed to cause meiotic defects in Mei025. INVAN6 interacts with itself as well as with four other CINs and seven 14‐3‐3 proteins. Although INVAN6Mei025, the variant of INVAN6 found in Mei025, lacks hydrolytic activity entirely, its presence is deleterious to male meiosis, possibly in a dominant negative repression manner through interacting with its partner proteins. Notably, heat stress aggravated meiotic defects in invan6 null mutant. Further transcriptome data suggest INVAN6 has a fundamental role for sugar homeostasis and stress tolerance of male meiocytes.In summary, this work uncovered the function of maize CIN in male meiosis and revealed the role of CIN‐mediated sugar metabolism and signalling in meiotic progression under heat stress. [ABSTRACT FROM AUTHOR]

Environmental factors are constantly changing in the intertidal region. Consequently, the various benthic organisms that densely colonize this ocean area had to adapt to these constant changes. Reproductive strategy might be considered one of these adaptations. However, knowledge about this aspect of the biology of marine invertebrates is still contentious for some groups, especially with regard to sponges (Porifera). Here, we investigated the effects of different environmental factors on the timing and effort of sexual and asexual reproduction in Cinachyrella apion and Tethya maza, two oviparous demosponges in Salvador, Bahia, Brazil. We analyzed the influence of humidity, atmospheric temperature, seawater temperature, photoperiod, rainfall, height of low tides, and chlorophyll‐a concentration on the density and size of oocytes and buds of these sponges. Both species reproduced aperiodically. Cinachyrella apion had a maximum 2.8 ± 4.04 oocytes/mm2 and 0.73 ± 0.15 buds/mm2, whereas T. maza had a maximum 6.0 ± 12.21 oocytes/mm2 and 0.31 ± 0.13 buds/mm2. The density of oocytes in C. apion was positively influenced by chlorophyll‐a concentration, whereas that of T. maza was negatively modulated by relative humidity. We did not observe any relationship between the environmental factors and bud density in C. apion, but bud density variation in T. maza was positively related to chlorophyll‐a concentration and to seawater temperature. It seems that individuals of both species alternated between the production of sexual and asexual propagules, suggesting a trade‐off between reproductive modes. Therefore, asexual and sexual reproduction seems to impact population growth and reproduction of both species, likely contributing to the recruitment of new sponges. In tropical intertidal regions, multiple environmental factors seem to contribute more to determining the quantity of sexual and asexual reproductive elements rather than the species' reproductive period. [ABSTRACT FROM AUTHOR]

The mud star Ctenodiscus crispatus has a broad distribution from Arctic waters into the northern Atlantic and Pacific oceans. Populations in the Atlantic are well studied and show oocyte sizes indicative of continuous gametogenesis with aseasonal spawning. In contrast, knowledge on the reproductive biology of Pacific populations is lacking. Thus, this study aims to examine the reproduction of C. crispatus in the northeastern Pacific. We sampled a population from the Pacific Ocean off Oregon and confirmed the species identity through 16S and cytochrome oxidase subunit I (COI) genetic barcoding. The majority of adults were 22–27 mm in size. Oocytes were obtained from dissected gonads soaked in a 1‐methyladenine solution and fertilized with spawned sperm. Other individuals were preserved whole in 10% buffered formalin, and oocytes were measured from preserved gonads. Strip‐spawned oocytes had a mean diameter of ~485 μm, consistent with Atlantic populations. Sperm had a mean head diameter and flagellum length of 3.1 and 65.9 μm, respectively. The time between first and second cell divisions was ~2 h, but larval cultures failed, and very few embryos developed to blastulae. Both strip‐spawned and preserved oocytes had a bimodal size‐frequency distribution indicative of semicontinuous gametogenesis. Comparison among individuals showed evidence of asynchrony among the population. This asynchrony and bimodal oocyte distribution may be driven by regular pulses of food, as has been postulated for other populations of this species. The reproductive plasticity seen among populations of this species in different regions could explain how it successfully inhabits such a wide geographic range. [ABSTRACT FROM AUTHOR]

Double fertilization is an innovative phenomenon in angiosperms, in which one sperm cell first fuses with the egg cell to produce the embryo, and then the other sperm fuses with the central cell to produce the endosperm. However, the molecular mechanism of the preferential fertilization of egg cells is poorly understood. In this study, we report that two egg cell‐secreted aspartic proteases, ECS1 and ECS2, play an important role in promoting preferential fertilization of egg cells in Arabidopsis. We show that simultaneous loss of ECS1 and ECS2 function resulted in an approximately 20% reduction in fertility, which can be complemented by the full‐length ECS1/2 but not by corresponding active site mutants or by secretion‐defective versions of ECS1/2. Detailed phenotypic analysis revealed that the egg cell–sperm cell attachment was compromised in ecs1 ecs2 siliques. Limited pollination assays with cyclin‐dependent kinase a1 (cdka;1) pollen showed that preferential egg cell fertilization was impaired in the ecs1 ecs2 mutant. Taken together, these results demonstrate that egg cells secret two aspartic proteases, ECS1 and ECS2, to facilitate the attachment of sperm cells to egg cells so that preferential fertilization of egg cells is achieved. This study reveals the molecular mechanism of preferential fertilization in Arabidopsis thaliana. [ABSTRACT FROM AUTHOR]

Impacts of global warming and CO2‐related ocean acidification (OA) on fish reproduction may include chronic effects on gametogenesis and gamete quality, as well as acute effects on external fertilisation. Here, temperature thresholds and OA‐sensitivity of gametogenesis and fertilisation were investigated in Atlantic cod, Gadus morhua. Three broodstock groups of farmed cod (FC 1–3) were exposed for 3 months to three maturation conditions (FC 1: control, 6°C/400 μatm CO2; FC 2: warming, 9.5°C/400 μatm; FC 3: warming and OA, 9.5°C/1100 μatm). In addition, a broodstock group of wild cod (WC) was kept at control conditions to compare the acute temperature window of fertilisation with that of farmed cod (FC 1). Fertilisations were conducted in a temperature‐gradient table at 10 temperatures (between −1.5 and 12°C) and two CO2 levels (400/1100 μatm). In FC 1 and WC, fertilisation success was relatively high between 0.5°C and 11°C (TRange of c. 10.5°C), indicating similar gamete quality in farmed and wild broodstocks kept at control conditions. Exposure of farmed broodstocks to warming (FC 2) and the combination of warming and OA (FC 3) impaired gamete quality, causing a reduction in fertilisation success of −20% (FC 2) and − 42% (FC 3) compared to FC 1. The acute temperature window of fertilisation narrowed from FC 1 (TRange = 10.4°C) to FC 2 (TRange = 8.8°C) and FC 3 (TRange = 5.9°C). Acute effects of CO2 on fertilisation success were not significant. This study demonstrates potential climate change impacts on gametogenesis and fertilisation in Atlantic cod, suggesting the loss of spawning habitat in the coming decades. [ABSTRACT FROM AUTHOR]

Specimens of a new species of torquaratorid acorn worm (Hemichordata, Enteropneusta) were video recorded and subsequently collected at abyssal depths in the eastern North Pacific at sites ranging from Oregon to northern Mexico. These worms are described here as Yoda demiankoopi n. sp. by molecular and morphological methods. The new species differs from its only described congener, Yoda purpurata, in three ways. First, the lips are extremely wide and indented by a deep ciliary groove for ingesting substrate and conveying it to the mouth. Second, a connective tissue bulge of unknown significance runs mid‐dorsally along the hepatic and posthepatic regions of the intestine. Third, the posthepatic intestine is strikingly sinuous and packed with gut contents presumably undergoing digestion for extended periods between infrequent defecations. Yoda demiankoopi n. sp. is hermaphroditic, a character so far known only for the genus Yoda in the entire class Enteropneusta. The gonads of each adult worm comprise hundreds of ovaries (each containing a single oocyte) and hundreds of testes located just beneath the dorsal epidermis of the anterior trunk and associated genital wings. In any given animal, at any given time, gametes of only one sex or the other become fully mature. Thus, the worm is a sequential hermaphrodite, alternately spawning purely as a female or purely as a male. [ABSTRACT FROM AUTHOR]

Sexual selection influences the evolution of phenotypic traits and contributes to patterns of biodiversity. In many animals, mating involves sequential steps. Often, individuals must secure resources that are essential for mating (nests, territories, food), and then after securing a resource, individuals engage in competition for access to limited opposite sex mates and gametes. A large body of empirical research and some verbal models have illustrated that resource acquisition can influence sexual selection. In general, though, we lack a priori predictions of when and how resource acquisition will influence sexual selection. Here, we use a mathematical framework to explore the link between resource acquisition and sexual selection on an advantageous mate‐acquisition trait across biologically relevant trade‐off scenarios. Our findings provide a set of testable predictions of how resource acquisition can influence sexual selection on mating traits. In general, selection on mate‐acquisition traits is expected to be heavily influenced by: (1) the episode of selection considered, and in particular, whether one considers selection associated with the mating pool only or selection associated with both the mating pool and pre‐mating pool; (2) whether resource‐acquisition and mate‐acquisition traits are positively associated or whether they trade off; and (3) the proportion of males with the resource‐ and mate‐acquisition traits. [ABSTRACT FROM AUTHOR]

Ageing severely affects the chromosome segregation process in human oocytes resulting in aneuploidy, infertility and developmental disorders. A considerable amount of segregation errors in humans are introduced at the second meiotic division. We have here compared the chromosome segregation process in young adult and aged female mice during the second meiotic division. More than half of the oocytes in aged mice displayed chromosome segregation irregularities at anaphase II, resulting in dramatically increased level of aneuploidy in haploid gametes, from 4% in young adult mice to 30% in aged mice. We find that the post‐metaphase II process that efficiently corrects aberrant kinetochore‐microtubule attachments in oocytes in young adult mice is approximately 10‐fold less efficient in aged mice, in particular affecting chromosomes that show small inter‐centromere distances at the metaphase II stage in aged mice. Our results reveal that post‐metaphase II processes have critical impact on age‐dependent aneuploidy in mammalian eggs. [ABSTRACT FROM AUTHOR]

Assisted reproductive technologies (ARTs) were legitimized in Iran through the rulings (fatwa) of some of the Shia Islamic jurists, who, in allowing third‐party gamete donation, specified that the resulting child will belong to its biological parent from whom it will take its lineage and inherit. However, three decades on and in practice, the recipients of gamete are increasingly resorting to seeking third‐party gamete from anonymous donors, an act which defies the above rulings. Currently, a proposal including legalizing anonymous gamete donation is examined by the parliament and the question of anonymity remains in flux. This article examines the factors leading to the emergence of the preference by both the infertile couples and the practitioners for anonymous donation. It further examines the implications of anonymous gamete donation for lineage and biological relatedness, which form the cornerstone of family and kinship, and which are paramount in Islam and in Iranian culture. [ABSTRACT FROM AUTHOR]

SUMMARY: Through the inactivation of genes that act during meiosis it is possible to direct the genetic make‐up of plants in subsequent generations and optimize breeding schemes. Offspring may show higher recombination of parental alleles resulting from elevated crossover (CO) incidence, or by omission of meiotic divisions, offspring may become polyploid. However, stable mutations in genes essential for recombination, or for either one of the two meiotic divisions, can have pleiotropic effects on plant morphology and line stability, for instance by causing lower fertility. Therefore, it is often favorable to temporarily change gene expression during meiosis rather than relying on stable null mutants. It was previously shown that virus‐induced gene silencing (VIGS) can be used to transiently reduce CO frequencies. We asked if VIGS could also be used to modify other processes throughout meiosis and during pollen formation in Arabidopsis thaliana. Here, we show that VIGS‐mediated knock‐down of FIGL1, RECQ4A/B, OSD1 and QRT2 can induce (i) an increase in chiasma numbers, (ii) unreduced gametes and (iii) pollen tetrads. We further show that VIGS can target both sexes and different genetic backgrounds and can simultaneously silence different gene copies. The successful knock‐down of these genes in A. thaliana suggests that VIGS can be exploited to manipulate any process during or shortly after meiosis. Hence, the transient induction of changes in inheritance patterns can be used as a powerful tool for applied research and biotechnological applications. Significance Statement: The present work demonstrates that VIGS is an efficient tool to quickly accomplish breeding aims such as an increase in crossover recombination, the generation of polyploid offspring and modification of pollen‐specific processes. [ABSTRACT FROM AUTHOR]

Heritable traits are predominantly encoded within genomic DNA, but it is now appreciated that epigenetic information is also inherited through DNA methylation, histone modifications, and small RNAs. Several examples of transgenerational epigenetic inheritance of traits have been documented in plants and animals. These include even the inheritance of traits acquired through the soma during the life of an organism, implicating the transfer of epigenetic information via the germline to the next generation. Small RNAs appear to play a significant role in carrying epigenetic information across generations. This review focuses on how epigenetic information in the form of small RNAs is transmitted from the germline to the embryos through the gametes. We also consider how inherited epigenetic information is maintained across generations in a small RNA‐dependent and independent manner. Finally, we discuss how epigenetic traits acquired from the soma can be inherited through small RNAs. [ABSTRACT FROM AUTHOR]

Development of sexual characters and generation of gametes are tightly coupled with growth. Platynereis dumerilii is a marine annelid that has been used to study germline development and gametogenesis. P. dumerilii has germ cell clusters found across the body in the juvenile worms, and the clusters eventually form the gametes. Like other segmented worms, P. dumerilii grows by adding new segments at its posterior end. The number of segments reflect the growth state of the worms and therefore is a useful and measurable growth state metric to study the growth‐reproduction crosstalk. To understand how growth correlates with progression of gametogenesis, we investigated germline development across several developmental stages. We discovered a distinct transition period when worms increase the number of germline clusters at a particular segment number threshold. Additionally, we found that keeping worms short in segment number, by manipulating environmental conditions or via amputations, supported a segment number threshold requirement for germline development. Finally, we asked if these clusters in P. dumerilii play a role in regeneration (as similar free‐roaming cells are observed in Hydra and planarian regeneration) and found that the clusters were not required for regeneration in P. dumerilii, suggesting a strictly germline nature. Overall, these molecular analyses suggest a previously unidentified developmental transition dependent on the growth state of juvenile P. dumerilii leading to substantially increased germline expansion. HIGHLIGHTS: Total segment number predicts the state of germline development and the abundance of germline clusters in Platynereis dumerilii.Changing environmental conditions or amputating worms do not alter the segment number threshold requirement for germline development.The vasa‐expressing germ clusters are not required for regeneration in Platynereis dumerilii. [ABSTRACT FROM AUTHOR]

Females in mutually ornamented species are often less conspicuously ornamented than their male conspecifics. It has been hypothesized that offspring quality may decrease if females invest more resources into ornaments at the expense of resources in eggs. An experiment was carried out to test whether natural variation in carotenoid in the eggs from a wild population of Arctic charr (Salvelinus alpinus) was associated with survival and growth of their offspring until hatching. Wild Arctic charr were caught at a spawning ground during the spawning period. Eggs from two different females, one female with yellowish carotenoid‐rich eggs and one with paler eggs, were fertilized by sperm from the same male. This was repeated until gametes were collected from 42 females and 21 males, giving a total of 21 groups. After fertilization, the zygotes from each of the two females were reared in four replicated groups. These 168 groups were reared separately until hatching when the surviving larvae were counted and their body length measured. For the two response variables survival and body length at hatching, no effect was demonstrated of any of the predictors (i) amount of carotenoid in the unfertilized eggs, (ii) the mothers' body condition, or (iii) ornament intensity of their red carotenoid‐based abdominal ornament. Thus, this study gives no support for the hypothesis that females investing less carotenoid into their eggs suffer from decreased offspring quality until hatching. This lack of association between female ornament intensity and their fitness is not as expected if female ornaments evolved due to direct sexual selection from males on the more ornamented females ("direct selection hypothesis"). [ABSTRACT FROM AUTHOR]

Most organisms reproduce seasonally, including most species of marine invertebrates that live across wide ranges in habitat, depth and environmental conditions. We asked: What ultimately selects for seasonal reproduction in benthic marine invertebrates with planktotrophic larvae (characteristic of ≥70% of marine invertebrates)? We hypothesized that seasonal variation in food available for the larvae ultimately selects for timing of adult reproduction. Testing this hypothesis requires a whole life cycle perspective and approach. Using a known proximate cue, daylength, we shifted gametogenesis in the laboratory by six months in a seasonally breeding temperate sea star, the Ochre Star Pisaster ochraceus (Brandt 1835). We were then able to induce spawning, fertilize gametes and culture resulting embryos in vitro to produce feeding larvae six months out of phase with natural photoperiod. We field‐reared these out‐of‐season larvae, similarly produced in‐season conspecifics and similar larvae of an aseasonally breeding asteroid, the Bat Star Patiria miniata (Brandt 1835) in mesh‐covered flow‐through containers that were deployed in seasonally contrasting oceanographic conditions reflecting different productivity regimes and larval food availability in spring and fall. Larval development and survival were similar between seasons: for example, planktonic larval duration was 48 d to first metamorphosis in spring vs. 45 d in fall for P. ochraceus. Hence, temporal variation in available phytoplankton may not be an ultimate selection factor acting on these larvae to regulate timing of seasonal reproduction in the adults. Alternatively, in this and other species of marine invertebrates, selection acting on early benthic juveniles or other life stages may determine the timing of adult reproduction. [ABSTRACT FROM AUTHOR]

Premise: Apomixis and hybridization are two essential and complementary factors in the evolution of plants, including ferns. Hybridization combines characteristics from different species, while apomixis conserves features within a lineage. When combined, these two processes result in apo‐sex hybrids. The conditions leading to the formation of these hybrids are poorly understood in ferns. Methods: We cultivated spores from 66 fern samples (43 apomicts, 7 apo‐sex hybrids, and 16 sexuals), and measured their development in vitro over 16 weeks. We evaluated germination, lateral meristem formation rates, sexual expression, and production of sporophytes and then compared ontogenetic patterns among the three groups. Results: The three examined groups formed antheridia (male gametangia) but differed in overall gametophyte development. Sexual species created archegonia (female, 86% of viable samples), but no sporophytes. Apomicts rarely created nonfunctional archegonia (8%) but usually produced apogamous sporophytes (75%). Surprisingly, apomictic and sexual species showed similar development speed. The sexually reproducing parents of viable studied hybrids formed about twice as many meristic gametophytes as the apomictic parents (39% vs. 20%, respectively). Conclusions: We present the most thorough comparison of gametangial development of sexual and apomictic ferns, to date. Despite expectations, apomictic reproduction might not lead to earlier sporophyte formation. Apomicts produce functional sperm and thus can contribute this type of gamete to their hybrids. The development patterns found in the parents of hybrids indicate a possible increase of hybridization rates by antheridiogens. The apo‐sex hybrids always inherit the apomictic reproductive strategy and are thus capable of self‐perpetuation. [ABSTRACT FROM AUTHOR]

Summary: Although land plant germ cells have received much attention, knowledge about their specification is still limited. We thus identified transcripts enriched in egg cells of the bryophyte model species Physcomitrium patens, compared the results with angiosperm egg cells, and selected important candidate genes for functional analysis.We used laser‐assisted microdissection to perform a cell‐type‐specific transcriptome analysis on egg cells for comparison with available expression profiles of vegetative tissues and male reproductive organs. We made reporter lines and knockout mutants of the two BONOBO (PbBNB) genes and studied their role in reproduction.We observed an overlap in gene activity between bryophyte and angiosperm egg cells, but also clear differences. Strikingly, several processes that are male‐germline specific in Arabidopsis are active in the P. patens egg cell. Among those were the moss PbBNB genes, which control proliferation and identity of both female and male germlines.Pathways shared between male and female germlines were most likely present in the common ancestors of land plants, besides sex‐specifying factors. A set of genes may also be involved in the switches between the diploid and haploid moss generations. Nonangiosperm gene networks also contribute to the specification of the P. patens egg cell. [ABSTRACT FROM AUTHOR]

This essay presents a hypothesis which contends that the development of organismic complexity in the eukaryotes depended extensively on propagation via flagellated and ciliated gametes. Organisms utilizing flagellate and ciliate gametes to propagate their germ line have contributed most of the organismic complexity found in the higher animals. The genes of the flagellum and the flagellar assembly system (intraflagellar transport) have played a disproportionately important role in the construction of complex tissues and organs. The hypothesis also proposes that competition between large numbers of haploid flagellated male gametes rigorously conserved the functionality of a key set of flagellar genes for more than 700 million years. This in turn has insured that a large set (>600) of highly functional cytoskeletal and signal pathway genes is always present in the lineage of organisms with flagellated or ciliated gametes to act as a dependable resource, or "toolkit," for organ elaboration. Also see the video abstract here: https://youtu.be/lC5nC-WOcm8 [ABSTRACT FROM AUTHOR]

The clinical applications of donated gametes are approved in many countries; however, attitudes toward its application and national legislation in some countries are challenging. The purpose of this study is to report a healthy live birth produced by vitrified‐warmed oocytes and frozen‐thawed testicular sperms to avoid sperm donation. [ABSTRACT FROM AUTHOR]

As for the number of sperm cells in the image, it is, in our case, relatively easy to distinguish whether there is only one sperm cell or two sperm cells sitting beside the egg cell under NIKON A1R microscope with a 40× magnification objective lens (1.15 WI). The results showed that the detained sperm cell beside the egg cell indeed possessed intact plasma membrane and nucleus (Figure 1E), indicating that membrane fusion indeed did not occur between the detained sperm cell and the egg cell, supporting the conclusion in [2]. Furthermore, we identified two fertilization-related phenotypes in the I ecs1-1 ecs2-1 i mutant, that is, unfertilized egg cell plus fertilized or unfertilized central cell, therefore, when the retaining of a sperm cell was examined, the egg cell in the ovule was first confirmed to be unfertilized. We observed that 8.3% ± 2.8% ovules with one sperm cell and 2.0% ± 1.4% ovules with one sperm cell pair being detained outside the egg cell (Figure 1C, D), consistent with the results reported in [2], clearly indicating that the persistent sperm cell/the pair of sperm cells in the ovule was not from the fertilization recovery-induced secondary pollen tubes, excluding the possibility raised in [9]. [Extracted from the article]

A number of online fora and registers have been established because many parents, donor-conceived people, and donors are faced with questions about how to be a donor family and wish to learn more about it or potentially connect with genetic relatives. Participants included representatives from public and private fertility clinics, gamete donors, parents to donor-conceived children, donor-conceived people, private sperm and egg banks, and researchers within the field. Donors' relatives may also face DNA surprises if the donor kept their donor status a secret. [Extracted from the article]