Female Sperm Research Articles

Selection on sperm size in response to promiscuity and variation in female sperm storage organs.

Sperm cells are exceptionally morphologically diverse across taxa. However, morphology can be quite uniform within species, particularly for species where females copulate with many males per reproductive bout. Strong sexual selection in these promiscuous species is widely hypothesized to reduce intraspecific sperm variation. Conversely, we hypothesize that intraspecific sperm size variation may be maintained by high among-female variation in the size of sperm storage organs, assuming that paternity success improves when sperm are compatible in size with the sperm storage organ. We use individual-based simulations and an analytical model to evaluate how selection on sperm size depends on promiscuity level and variation in sperm storage organ size (hereafter, female preference variation). Simulations of high promiscuity (10 mates per female) showed stabilizing selection on sperm when female preference variation was low, and disruptive selection when female preference variation was high, consistent with the analytical model results. With low promiscuity (2-3 mates per female), selection on sperm was stabilizing for all levels of female preference variation in the simulations, contrasting with the analytical model. Promiscuity level, or mate sampling, thus has a strong impact on the selection resulting from female preferences. Furthermore, when promiscuity is low, disruptive selection on male traits will occur under much more limited circumstances (i.e. only with higher among-female variation) than many previous models suggest. Variation in female sperm storage organs likely has strong implications for intraspecific sperm variation in highly promiscuous species, but likely does not explain differences in intraspecific sperm variation for less promiscuous taxa.

Molecular detection of Vibrio paraheamolyticus in a sperm whale (Physeter macrocephalus) stranding in northern Veracruz, Mexico.

On 25 August 2021, a single female sperm whale (Physeter macrocephalus) was found stranded dead in Playa Tuxpan, Veracruz, Mexico. Skin biopsies were obtained and screened for the detection of various potentially pathogenic bacterial genera, using conventional polymerase chain reaction and sequencing of the positive amplicons. We recorded, for the first time, the presence of Vibrio paraheamolyticus in skin samples from P. macrocephalus in the Gulf of Mexico. Additionally, we discuss 29 records reporting strandings of sperm whales from six states of the Mexican Republic. Most of the records are concentrated in the Pacific Ocean. Our findings increase the inventory of bacteria reported in P. macrocephalus worldwide, summarising the knowledge of stranding events in sperm whale populations in Mexico.

Developing machine learning-based models to predict intrauterine insemination (IUI) success by address modeling challenges in imbalanced data and providing modification solutions for them

BackgroundThis study sought to provide machine learning-based classification models to predict the success of intrauterine insemination (IUI) therapy. Additionally, we sought to illustrate the effect of models fitting with balanced data vs original data with imbalanced data labels using two different types of resampling methods. Finally, we fit models with all features against optimized feature sets using various feature selection techniques.MethodsThe data for the cross-sectional study were collected from 546 infertile couples with IUI at the Fatemehzahra Infertility Research Center, Babol, North of Iran. Logistic regression (LR), support vector classification, random forest, Extreme Gradient Boosting (XGBoost) and, Stacking generalization (Stack) as the machine learning classifiers were used to predict IUI success by Python v3.7. We employed the Smote-Tomek (Stomek) and Smote-ENN (SENN) resampling methods to address the imbalance problem in the original dataset. Furthermore, to increase the performance of the models, mutual information classification (MIC-FS), genetic algorithm (GA-FS), and random forest (RF-FS) were used to select the ideal feature sets for model development.ResultsIn this study, 28% of patients undergoing IUI treatment obtained a successful pregnancy. Also, the average age of women and men was 24.98 and 29.85 years, respectively. The calibration plot in this study for IUI success prediction by machine learning models showed that between feature selection methods, the RF-FS, and among the datasets used to fit the models, the balanced dataset with the Stomek method had well-calibrating predictions than other methods. Finally, the brier scores for the LR, SVC, RF, XGBoost, and Stack models that were fitted utilizing the Stomek dataset and the chosen feature set using the Random Forest technique obtained equal to 0.202, 0.183, 0.158, 0.129, and 0.134, respectively. It showed duration of infertility, male and female age, sperm concentration, and sperm motility grading score as the most predictable factors in IUI success.ConclusionThe results of this study with the XGBoost prediction model can be used to foretell the individual success of IUI for each couple before initiating therapy.

Reproductive Behaviour of 150-Gy-Treated Female Lobesia botrana (Lepidoptera: Tortricidae).

Simple SummaryEnvironment-friendly and sustainable insect pest control approaches such as the sterile insect technique/inherited sterility (SIT/IS) have been proposed against the European grapevine moth Lobesia botrana. Reproductive behaviour, such as oviposition, mating ability, and multiple mating of 150 Gy-treated females, was studied. Moreover, the last-male sperm precedence (P2 value) and male’s flight response to treated females were also investigated. The present study aims to provide basic information which is essential to ensure successful implementation of SIT/IS as part of an integrated approach for the management of L. botrana.The sterile insect technique/inherited sterility (SIT/IS) has been suggested as an eco-friendly control tactic for area-wide integrated pest management approaches in order to control the European grapevine moth, Lobesia botrana. This study assessed the effects of an irradiation dose of 150 Gy administered to newly emerged female moths on their egg laying behaviour and mating ability at different ages at mating. Moreover, the effects of multiple mating on the mating ability of treated females, pattern of sperm precedence in twice-mated females and the flight response of treated and untreated males to treated and untreated calling females were also investigated. Females treated with 150 Gy initiated calling in a way similar to untreated females. When treated females were paired with untreated males, the mean number of eggs oviposited per female during 6 days was reduced (59.6 and 82.8 eggs/female, respectively), as was their mating ability and multiple mating compared with untreated females. The proportion of offspring fertilized by the second of the two males to mate with the female or last-male sperm precedence (P2 value) constituted 97% of the eggs, suggesting that the second male mate fathered the most offspring. The outcome of this work could be viewed as an integrated approach for improving effectiveness and enabling successful implementation of a SIT/IS program against L. botrana.

P-597 The effects of triple trigger on IVF outcomes and pregnancy rates in poor responder patients

Abstract Study question Are there any positive effects of triple trigger on oocyte morphology, embryo quality and pregnancy rates in poor responder (POR) patients? Summary answer The trigger with human chorionic gonadotropin (hCG), gonadotropin-releasing hormone agonist (GnRHa) and human menopausal gonadotropin (hMG) may improve embryo quality and pregnancy rates in POR. What is known already The ESHRE consensus criteria define a poor ovarian response (POR) as less than four oocytes retrieved. Advanced female age and severe sperm disorder were associated fertilization failure after intracytoplasmic sperm injection (ICSI). Also, oocyte quality is pivotal to determine the fertilization of the oocyte. Hence there is no study to evaluate triple trigger on the embryo quality in POR and severe male infertility are excluded. Study design, size, duration In this prospective randomized study, we analyzed poor responder patients that have history of fertilization failure and cleavage arrest embryo, including 100 patients with only hCG trigger (group 1), 100 patients with dual trigger hCG + GnRHa (Group 2), and 100 patients with triple trigger hCG + GnRHa + hMG (Group 3). Patients who have the POR criteria according to MII oocytes lower than 4 were included in the analysis. Participants/materials, setting, methods Mean age, body mass index (BMI), AMH levels, day-2 FSH and E2, duration of infertility, LH and E2 levels on trigger day, duration of stimulation, total dose of gonadotropins used, number of previous trials, MII oocytes were examined and compared between the groups. Sperm concentration under 5 x 106 mL was not included to exclude severe male factor. Embryo quality, pregnancy rates evaluation was performed for each patient that has been performed GnRH antagonist protocols. Main results and the role of chance Age, Body Mass Index (BMI), AMH levels, day 2 FSH and E2, duration of infertility, duration of stimulation, E2 levels on trigger day, and total dose of gonadotropins usage between the three groups were similar. Number of MII oocytes, fertilization (2PN), and D5 (blastocyst) embryo transfer were significantly higher in Group 3 (Table 1). Pregnancy rates are higher in group 3 however significantly not significant. Limitations, reasons for caution The study is limited by its sample size and a higher sample size might be used in the future studies to corroborate the current findings. hMG trigger dosage may be arranged in another study. Wider implications of the findings Our results showed that the number of MII oocytes 2PN levels, D5 ET were higher in DOR patients triggered with hCG + GnRHa + hMG. Trial registration number 28012022

First insights into female sperm storage duration in tardigrades.

Female sperm storage is ubiquitous in the animal kingdom and it has been shown to be linked to several evolutionary processes, from postcopulatory sexual selection to dispersal. Here we report, for the first time, long‐term sperm storage in females of the tardigrade Macrobiotus polonicus. Females, isolated after a short contact with a male, were able to use the stored sperm for up to 5 weeks (mean of 2 weeks), which translates to a considerable proportion of female post‐mating longevity under controlled laboratory conditions (60% on average). Our study provides the first insights into the duration of sperm storage, an underexplored feature of the reproductive biology of tardigrades. Additionally, we discuss important considerations for reproductive studies on these non‐model animals.

Putative Degradation of Non-Stored Sperm in the Female Reproductive Tract of the Dengue Vector Mosquito Aedes aegypti

In insect vectors of disease, male and female molecules that mediate reproductive processes are promising targets to suppress fertility of these populations. One process, the storage of sperm in the female reproductive tract, is essential for optimal fertility in all organisms examined to date. In the dengue vector mosquito Aedes aegypti, female sperm storage has not been fully characterized, a requirement to identify sex-specific molecules that mediate this process. Aedes aegypti males deposit the ejaculate into the bursa of the female reproductive tract, and sperm enter the spermathecae—the long-term storage sites—quickly after insemination. However, the proportion of sperm received during mating that are stored in the spermathecae is unclear, and the fate of non-stored sperm unknown. We quantified sperm storage in two Ae. aegypti strains, mated in all combinations, and in two contexts (mass mated and when mating was observed) at 1-, 3- and 5-days post-mating. Sperm quantity in the spermathecae was similar at all timepoints; most females stored ~400 sperm on average. Sperm that did not enter the spermathecae remained in the bursa, where they declined in number and became more fragile to mechanical manipulation at each timepoint. Further, sperm viability in the bursa fell from 91.6% shortly after mating to 12.2% 24 h later. One day after insemination, ~50% of sperm detected in the female reproductive tract was stored in the spermathecae. When we quantified sperm storage in females mated to males that transferred reduced ejaculate quantities (but still able to induce optimal fertility in their mates), sperm detected in the spermathecae similarly declined; females stored ~50% of the sperm received even as sperm quantities transferred at mating declined. Our results suggest that sperm storage in Ae. aegypti females is influenced by ejaculate volume, and that sperm that do not enter the spermathecae remain in the bursa, where they appear to degrade. The consistent presence of sperm in the bursa, even when males transferred low sperm quantities, suggests that the putative degradation of bursa sperm may play a role in Ae. aegypti female fertility, potentially identifying a novel process in this important vector species.

How the female reproductive tract guides sperm before fertilization

How the female reproductive tract guides sperm before fertilization

Art’s Work in the Age of Biotechnology: Shaping Our Genetic Futures

Art’s Work in the Age of Biotechnology: Shaping Our Genetic Futures

Patterns of Remating Behaviour in Ceratitis (Diptera: Tephritidae) Species of Varying Lifespan.

Trade-offs between life-history traits offset the energetic costs of maintaining fitness in complex environments. Ceratitis species have been recorded to have long lifespans, which may have evolved in response to seasonal resource fluctuation. It is thus likely that reproductive patterns have evolved concomitantly as part of the trade-off between lifespan and reproduction. In this study, we investigated how reproductive patterns differ between Ceratitis cosyra (Walker) and Ceratitis capitata (Wiedemann; Diptera: Tephritidae), two species with different average and maximum lifespans. Females of both species were mated and patterns of female survival, fecundity, remating and sperm storage were tested. Ceratitis cosyra had a higher rate of survival and a lower fecundity when compared with the shorter-lived C. capitata, suggesting that both species exhibit a trade-off between lifespan and reproduction. Both species showed a similar and consistent willingness to remate, despite declines in sperm storage, suggesting that sperm alone does not fully inhibit remating. As expected, C. cosyra transferred high numbers of sperm during the first mating. However, sperm stores declined unexpectedly by 14 days. This indicates that males might transfer large ejaculates as a nuptial gift, that females then later degrade as a source of nutrients. Large declines in sperm storage may also indicate that females discard excess sperm stores due to the toxicity involved with storing sperm. These results do not suggest that patterns of sperm storage and remating align with lifespan and resource seasonality in these species, but a wider range of species needs to be assessed to better understand variation in Ceratitis mating systems.

Female fruit flies cannot protect stored sperm from high temperature damage

Recently, it has been demonstrated that heat-induced male sterility is likely to shape population persistence as climate change progresses. However, an under-explored possibility is that females may be able to successfully store and preserve sperm at temperatures that sterilise males, which could ameliorate the impact of male infertility on populations. Here, we test whether females from two fruit fly species can protect stored sperm from a high temperature stress. We find that sperm carried by female Drosophila virilis are almost completely sterilised by high temperatures, whereas sperm carried by female Zaprionus indianus show only slightly reduced fertility. Heat-shocked D. virilis females can recover fertility when allowed to remate, suggesting that the delivered heat-shock is damaging stored sperm and not directly damaging females in this species. The temperatures required to reduce fertility of mated females are substantially lower than the temperatures required to damage mature sperm in males, suggesting that females are worse than males at protecting mature sperm. This suggests that female sperm storage is unlikely to ameliorate the impacts of high temperature fertility losses in males, and instead exacerbates fertility costs of high temperatures, representing an important determinant of population persistence during climate change.

Limitations of sperm transfer in the complex reproductive system of spiders

Abstract In spiders, sperm transfer from the male to the female is indirect via secondary copulatory structures, the pedipalps. At the time of transfer the sperm are not mobile and the ejaculate needs to move through narrow male and female ducts to the female sperm storage organ. In addition, copulation duration can be very short, often limited to just a few seconds. Finally, sexual cannibalism and genital damage limits male life-time mating opportunities. These features of the reproductive biology in spiders are likely to result in sperm transfer constraints. Here we review the intrinsic and extrinsic sperm transfer limitations and conduct a meta-analysis on sperm transfer data from published data. Most of the information available relates to orb-web spiders, but our meta-analysis also includes non-orb-web spiders. Our review identifies some of the behavioural factors that have been shown to influence sperm transfer, and lists several morphological and physiological traits where we do not yet know how they might affect sperm transfer.

Functional biologically active feed additive for breeding stock of fish

The work is devoted to the development and evaluation of the complex effect of a biologically active feed additive that meets the requirements of a functional feeding complex that ensures the regulation of physiological processes in the body of female breeding stock. In particular, influence of feed additives and its components on growth rate, quality of sexual products, reproductive process, embryogenesis, level of anomalies in the development of offspring, its growth potential was studied. The biologically active feed additive for the breeding stock included probiotic «Sporotermin», adaptogen «Trekrezan», vitamin-amino acid complex «Chiktonik». The hypothesis was tested that the developed feed additive, due to the peculiarities of its composition, is able to increase the growth rate of fish, optimize gametogenesis, reduce the level of pathology during embryonic development, increase the yield of larvae, increase their viability, reduce the level of developmental anomalies, increase survival and safety. The research results showed that the biologically active feed additive reduced the time of fish rearing, had a positive effect on the quality of female eggs and sperm in males, increased the quality characteristics of eggs, reduced the level of embryonic death during embryo incubation, increased the yield of larvae and their safety.

The influence of the female reproductive tract and sperm features on the design of microfluidic sperm-sorting devices.

Although medical advancements have successfully helped a lot of couples with their infertility by assisted reproductive technologies (ART), sperm selection, a crucial stage in ART, has remained challenging. Therefore, we aimed to investigate novel sperm separation methods, specifically microfluidic systems, as they do sperm selection based on sperm and/or the female reproductive tract (FRT) features without inflicting any damage to the selected sperm during the process. In this review, after an exhaustive studying of FRT features, which can implement by microfluidics devices, the focus was centered on sperm selection and investigation devices. During this study, we tried not to only point to the deficiencies of these systems, but to put forth suggestions for their improvement as well.

Seminal fluid and spermatophore production in a western Atlantic invasive swimming crab, Charybdis hellerii, reveals a different pattern to Portunoidea

The male reproductive system in Portunoidea is voluminous in order to produce the sperm plug, avoiding sperm competition. The portunid crab, Charybdis hellerii, is a successful invasive species, and this study describes the male reproductive system under light and electron microscopy and evaluates the gonadosomatic index and spermatophore dehiscence compared to other species that produce a sperm plug. The reproductive system is small, and its gonadosomatic index much lower than those of other Portunoidea that produce a sperm plug. The spermatophores are stored in the anterior part of the vas deferens, which is uncommon in Brachyura. Lateral outpocketings are found in the short, middle, and posterior parts of the vasa deferentia, where spermatophores are not found. The seminal fluid composition is different from the species that produce sperm plug. The usual portunid spermatophore wall is absent and the round coenospermic to even cleistospermic spermatophores are enclosed by secretions. This mucous-type spermatophore undergoes dehiscence in seawater or when passing through the gonopod. C. hellerii differ from other Portunoidea described regarding a low amount of seminal fluid production, spermatophore storage, and not show traits of producing sperm plugs. These different male reproductive features can lead to different female sperm storage in Portunoidea.

A piece of the puzzle: analyses of recent strandings and historical records reveal new genetic and ecological insights on New Zealand sperm whales

Cetacean strandings provide important opportunities to extend current knowledge on species or populations, particularly for species that are notoriously difficult to study, such as sperm whales Physeter macrocephalus (parāoa). Between 25 May and 9 June 2018, 13 male sperm whales stranded in Taranaki, New Zealand (NZ), with an additional male stranding 1 mo later in Clifford Bay, Marlborough. We profiled these 14 males for mitochondrial DNA (mtDNA) and carbon and nitrogen stable isotopes to examine their similarity to sperm whales from other geographic areas. Analyses of mtDNA revealed 7 haplotypes, including 1 not previously described (‘New’), and an additional haplotype (‘M’) new to NZ that had been previously reported in sperm whales of the Pacific region. Analysis of rare haplotypes found in NZ males suggested genetic links within NZ and the Southwest Pacific. Differences in stable isotope ratios indicated that, despite the close temporal proximity of these stranding events, individuals originated from at least 2 separate groups, with the whale stranded in Clifford Bay identified as being a regular visitor to Kaikōura, South Island. The analysis of stranding records in NZ dating back to 1873 indicated an increase in recorded single strandings since 1970, and a peak in single strandings in the austral summer months, but no seasonality for mass strandings. Sex predicted latitudinal location for single strandings, with 95.1% of female strandings occurring north of 42° S, fitting the general global distribution of female sperm whales limited to lower latitudes. This study provides the first temporal and spatial assessment of sperm whale strandings in NZ and highlights the need for future research on movements and genetic exchange between NZ sperm whales and sperm whales in the wider Pacific region.

Single-nucleus transcriptomes reveal evolutionary and functional properties of cell types in the Drosophila accessory gland.

Many traits responsible for male reproduction evolve quickly, including gene expression phenotypes in germline and somatic male reproductive tissues. Rapid male evolution in polyandrous species is thought to be driven by competition among males for fertilizations and conflicts between male and female fitness interests that manifest in postcopulatory phenotypes. In Drosophila, seminal fluid proteins secreted by three major cell types of the male accessory gland and ejaculatory duct are required for female sperm storage and use, and influence female postcopulatory traits. Recent work has shown that these cell types have overlapping but distinct effects on female postcopulatory biology, yet relatively little is known about their evolutionary properties. Here, we use single-nucleus RNA-Seq of the accessory gland and ejaculatory duct from Drosophila melanogaster and two closely related species to comprehensively describe the cell diversity of these tissues and their transcriptome evolution for the first time. We find that seminal fluid transcripts are strongly partitioned across the major cell types, and expression of many other genes additionally defines each cell type. We also report previously undocumented diversity in main cells. Transcriptome divergence was found to be heterogeneous across cell types and lineages, revealing a complex evolutionary process. Furthermore, protein adaptation varied across cell types, with potential consequences for our understanding of selection on male postcopulatory traits.

Extra-pair paternity in the wood-feeding cockroach Cryptocercus punctulatus Scudder: Social but not genetic monogamy.

Subsocial Cryptocercus cockroaches are the sister group to termites and considered to be socially monogamous. Because genetic monogamy is a suggested requirement for evolution of cooperative breeding/eusociality, particularly in hymenopterans, clarification of the mating biology of Cryptocercus would help illuminate evolutionary trends in eusocial insects. To investigate possible extra-pair paternity in C.punctulatus, microsatellite markers were used to analyse offspring parentage, the stored sperm in females and results of experimental manipulation of sperm competition. Extra-pair paternity was common in field-collected families, but a lack of maternal alleles in several nymphs suggests sampling error or adoption. Isolating prereproductive pairs and assaying subsequently produced nymphs confirmed that nymphs lacked alleles from the pair male in 40% of families, with extra-pair male(s) siring 27%-77% of nymphs. Sperm of extra-pair males was detected in the spermatheca of 51% of paired prereproductive females. Mate switching and surgical manipulation of male mating ability indicated a tendency towards last male sperm precedence. Overall, the results demonstrate that about half of young females are serially monogamous during their maturational year, but bond, overwinter and produce their only set of offspring in company of the last mated male (=pair male). Repeated mating by the pair male increases the number of nymphs sired, but because many females use stored sperm of previous copulatory partners to fertilize eggs, pair males extend parental care to unrelated nymphs. The results suggest that genetic monogamy either developed in the termite ancestor after splitting from the Cryptocercus lineage, or that genetic monogamy may not be a strict prerequisite for the evolution of termite eusociality.

Histological findings of sperm storage in green turtle (Chelonia mydas) oviduct

Green turtles (Chelonia mydas) are seasonal breeders with a time lag between mating and nesting periods. We therefore investigated whether female turtles store sperm like some other animals by histologically and ultrastructurally analyzing oviducts collected from three mature female free-ranging green turtles during the breeding season in the Ogasawara Islands, Japan. The oviduct comprised an infundibulum, magnum, isthmus, uterus, and vagina. Sperm was found in the isthmus of all turtles examined. Some spermatozoa were found in the duct and acini of glands in the isthmus of two turtles with oviducts containing eggs, and a few were also located in the transition area between the uterus and vagina of one of the turtles. On the other hand, we also found abundant spermatozoa on the luminal surface of the isthmus of one turtle captured during mating. In most reptiles, fertilization occurs in the infundibulum or albumen region, and thus the isthmus near those areas might be suitable for storing sperm in female turtles.

A Taxonomic Survey of Female Oviducal Glands in Chondrichthyes: A Comparative Overview of Microanatomy in the Two Reproductive Modes.

Simple SummaryThe oviducal gland (OG) is a specialized region of the reproductive female system in cartilaginous fish located in the anterior oviduct. Its biological importance is closely related to the reproductive modalities of these species, and its basic function is the production of the egg jellies, the tertiary envelope formation (egg case in oviparous and candle case in viviparous) and sperm storage. Since knowledge on the overall process of Chondrichthyes reproduction is still scarce, in this study we conducted morphological and morphometrical analysis on the OGs belonging to several cartilaginous fish displaying two different reproductive modalities (oviparity and viviparity). Moreover, we paid particular attention to the fate of spermatozoa in the female reproductive tract, which would be useful to better understand the ecology and population dynamics of these species.Oviducal glands (OGs) are distinct expanded regions of the anterior portion of the oviduct, commonly found in chondrichthyans, which play a key role in the production of the egg in-vestments and in the female sperm storage (FSS). The FSS phenomenon has implications for understanding the reproductive ecology and management of exploited populations, but little information is available on its taxonomic extent. For the first time, mature OGs from three lecithotrophic oviparous and four yolk-sac viviparous species, all considered at risk from the fishing impacts in the central western Mediterranean Sea, were examined using light microscopy. The OG microanatomy, whose morphology is generally conserved in all species, shows differences within the two reproductive modalities. Oviparous species show a more developed baffle zone in respect to viviparous ones because of the production of different egg envelopes produced. Among oviparous species, Raja polystigma and Chimaera monstrosa show presence of sperm, but not sperm storage as observed, instead, in Galeus melastomus and in all the viviparous sharks, which preserve sperm inside of specialized structures in the terminal zone.