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Aside from inheriting half of the genome of each of our parents, we are born with a small number of novel mutations that occurred during gametogenesis and postzygotically. Recent genome and exome sequencing studies of parent–offspring trios have provided the first insights into the number and distribution of these de novo mutations in health and disease, pointing to risk factors that increase their number in the offspring. De novo mutations have been shown to be a major cause of severe early-onset genetic disorders such as intellectual disability, autism spectrum disorder, and other developmental diseases. In fact, the occurrence of novel mutations in each generation explains why these reproductively lethal disorders continue to occur in our population. Recent studies have also shown that de novo mutations are predominantly of paternal origin and that their number increases with advanced paternal age. Here, we review the recent literature on de novo mutations, covering their detection, biological characterization, and medical impact.

Transmission of the malaria parasite to the mosquito vector is critical for the completion of the sexual stage of the parasite life cycle and is dependent on the release of male gametes from the gametocyte body inside the mosquito midgut. In the present study, we demonstrate that PfCDPK4 is critical for male gametogenesis and is involved in phosphorylation of proteins essential for male gamete emergence. Gametocytes of the malaria parasite Plasmodium are taken up by the mosquito vector with an infectious blood meal, representing a critical stage for parasite transmission. Calcium-independent protein kinases (CDPKs) play key roles in calcium-mediated signaling across the complex life cycle of the parasite. We sought to understand their role in human parasite transmission from the host to the mosquito vector and thus investigated the role of the human-infective parasite Plasmodium falciparum CDPK4 in the parasite life cycle. P. falciparum cdpk4 − parasites created by targeted gene deletion showed no effect in blood stage development or gametocyte development. However, cdpk4 − parasites showed a severe defect in male gametogenesis and the emergence of flagellated male gametes. To understand the molecular underpinnings of this defect, we performed mass spectrometry-based phosphoproteomic analyses of wild-type and Plasmodium falciparum cdpk4 − late gametocyte stages to identify key CDPK4-mediated phosphorylation events that may be important for the regulation of male gametogenesis. We further employed in vitro assays to identify these putative substrates of Plasmodium falciparum CDPK4. This indicated that CDPK4 regulates male gametogenesis by directly or indirectly controlling key essential events, such as DNA replication, mRNA translation, and cell motility. Taken together, our work demonstrates that PfCDPK4 is a central kinase that regulates exflagellation and thereby is critical for parasite transmission to the mosquito vector. IMPORTANCE Transmission of the malaria parasite to the mosquito vector is critical for the completion of the sexual stage of the parasite life cycle and is dependent on the release of male gametes from the gametocyte body inside the mosquito midgut. In the present study, we demonstrate that PfCDPK4 is critical for male gametogenesis and is involved in phosphorylation of proteins essential for male gamete emergence. Targeting PfCDPK4 and its substrates may provide insights into achieving effective malaria transmission-blocking strategies.

Reproduction affects lifespan and fat metabolism across species, suggesting a shared regulatory axis. In Caenorhabditis elegans , ablation of germline stem cells leads to extended lifespan and increased fat storage. While many studies focus on germline-less glp-1(e2144) mutants, the hermaphroditic germline of C. elegans provides an excellent opportunity to study how distinct germline anomalies affect lifespan and fat metabolism. We compare metabolomic, transcriptomic, and genetic pathway differences among three sterile mutants: germline-less glp-1 , feminized fem-3 , and masculinized mog-3 . All three accumulate excess fat and share expression changes in stress response and metabolism genes. However, glp-1 mutants exhibit the most robust lifespan extension, fem-3 mutants live longer only at certain temperatures, and mog-3 mutants are markedly short-lived. The extended lifespan in fem-3 mutants require daf-16/FOXO , as in glp-1 mutants. In contrast, daf-16 is dispensable for the already shortened lifespan of mog-3 mutants. Interestingly, mog-3 partially mimics male/mating-induced demise, offering a simplified model to study metabolic and reproductive trade-offs underlying this phenomenon. Our data indicate that disrupting specific germ cell populations leads to distinct and complex physiological and longevity outcomes. These findings highlight the importance of investigating sex-dependent differences and underlying mechanisms to fully understand and potentially modulate these relationships. In Caenorhabditis elegans , ablation of germline stem cells leads to extended lifespan and increased fat storage. Here the authors show that disrupting distinct gametogenesis programs and germline progression in C. elegans triggers molecular responses that affect fat metabolism, stress resilience, and lifespan.

Key ideas from a workshop convened by the National Academies of Sciences, Engineering, and Medicine to discuss developments in IVG (National Academies of Sciences, Engineering, and Medicine 2023) chaired by Dr Eli Y. Adashi (former Dean of Medicine and Biological Sciences at Brown University). The authors are solely responsible for the content of this paper, which does not necessarily represent the views of the National Academies of Sciences, Engineering, and Medicine.

Background Air pollution is involved in many pathologies. These pollutants act through several mechanisms that can affect numerous physiological functions, including reproduction: as endocrine disruptors or reactive oxygen species inducers, and through the formation of DNA adducts and/or epigenetic modifications. We conducted a systematic review of the published literature on the impact of air pollution on reproductive function. Eligible studies were selected from an electronic literature search from the PUBMED database from January 2000 to February 2016 and associated references in published studies. Search terms included (1) ovary or follicle or oocyte or testis or testicular or sperm or spermatozoa or fertility or infertility and (2) air quality or O 3 or NO 2 or PM2.5 or diesel or SO 2 or traffic or PM10 or air pollution or air pollutants. The literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We have included the human and animal studies corresponding to the search terms and published in English. We have excluded articles whose results did not concern fertility or gamete function and those focused on cancer or allergy. We have also excluded genetic, auto-immune or iatrogenic causes of reduced reproduction function from our analysis. Finally, we have excluded animal data that does not concern mammals and studies based on results from in vitro culture. Data have been grouped according to the studied pollutants in order to synthetize their impact on fertility and the molecular pathways involved. Conclusion Both animal and human epidemiological studies support the idea that air pollutants cause defects during gametogenesis leading to a drop in reproductive capacities in exposed populations. Air quality has an impact on overall health as well as on the reproductive function, so increased awareness of environmental protection issues is needed among the general public and the authorities.

In volvocine algae, gametogenesis is triggered by different cues depending on the species and their sexual systems. In isogamous unicellular organisms such as Chlamydomonas reinhardtii , which produce gametes of equal size and morphology, nitrogen depletion induces gametogenesis. In contrast, in oogamous multicellular species of the genus Volvox , which produce large, immobile eggs and small motile sperm, male gametogenesis is induced by a sex pheromone secreted by sperm packets (SPs), i.e., bundles of male gametes. Eudorina , an anisogamous multicellular volvocine alga that produces motile gametes of different sizes, is known to form SPs under nitrogen-depleted conditions. Intriguingly, a pheromone-like factor, present in male conditioned medium (CM), has also been implicated in SP formation. To clarify the relative contributions of nitrogen starvation and pheromone signaling, we conducted semi-quantitative analyses of SP induction using synchronously cultured male colonies of Eudorina . When CM was added to male cultures during an early maturation stage, most colonies formed SPs regardless of nitrogen availability. However, when the CM was diluted 100- to 100,000-fold, SP formation was significantly more efficient under nitrogen-depleted conditions than under nitrogen-replete conditions. Notably, SPs never formed without the addition of CM, even in a nitrogen-depleted medium. The SP-inducing activity of the CM was found to markedly decrease with protease treatment. These findings suggest that spermatogenesis in Eudorina is induced by a proteinaceous sex pheromone secreted by male colonies, and that nitrogen depletion, while not essential, enhances this pheromone activity.

N6-Methyladenosine (m6A) RNA methylation plays important roles during development in different species. However, knowledge of m6A RNA methylation in monocots remains limited. In this study, we reported that OsFIP and OsMTA2 are the components of m6A RNA methyltransferase complex in rice and uncovered a previously unknown function of m6A RNA methylation in regulation of plant sporogenesis. Importantly, OsFIP is essential for rice male gametogenesis. Knocking out of OsFIP results in early degeneration of microspores at the vacuolated pollen stage and simultaneously causes abnormal meiosis in prophase I. We further analyzed the profile of rice m6A modification during sporogenesis in both WT and OsFIP loss-of-function plants, and identified a rice panicle specific m6A modification motif \"UGWAMH\". Interestingly, we found that OsFIP directly mediates the m6A methylation of a set of threonine protease and NTPase mRNAs and is essential for their expression and/or splicing, which in turn regulates the progress of sporogenesis. Our findings revealed for the first time that OsFIP plays an indispensable role in plant early sporogenesis. This study also provides evidence for the different functions of the m6A RNA methyltransferase complex between rice and Arabidopsis.

In mammals, primordial germ cells (PGCs) undergo global erasure of DNA methylation with delayed demethylation of germline genes and selective retention of DNA methylation at evolutionarily young retrotransposons. However, the molecular mechanisms of persistent DNA methylation in PGCs remain unclear. Here we report that resistance to DNA methylation reprogramming in PGCs requires UHRF2, the paralog of the DNMT1 cofactor UHRF1. PGCs from Uhrf2 knock-out mice show loss of retrotransposon DNA methylation, while DNA methylation is unaffected in somatic cells. This is not associated with changes in the expression of retrotransposons in E13.5 PGCs, indicating that other mechanisms compensate for retrotransposon control at this stage. Furthermore, Uhrf2 -deficient PGCs show precocious demethylation of germline genes and overexpress meiotic genes in females. Subsequently, Uhrf2 -deficient mice show impaired oocyte development and female-specific reduced fertility, as well as incomplete remethylation of retrotransposons during spermatogenesis. These findings reveal a crucial function for the UHRF1 paralog UHRF2 in controlling DNA methylation in the germline.

Background Gonad development and differentiation is an essential function for all sexually reproducing species, and many aspects of these developmental processes are highly conserved among the metazoa. However, the mechanisms underlying gonad development and gametogenesis remain unclear in Tridacna squamosa , a large-size bivalve of great ecological value. They are protandrous simultaneous hermaphrodites, with the male gonad maturing first, eventually followed by the female gonads. In this study, nine gonad libraries representing resting, male and hermaphrodite stages in T. squamosa were performed to identify the molecular mechanisms. Results Sixteen thousand four hundred ninety-one unigenes were annotated in the NCBI non-redundant protein database. Among the annotated unigenes, 5091 and 7328 unigenes were assigned to Gene Ontology categories and the Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway database, respectively. A total of 4763 differentially expressed genes (DEGs) were identified by comparing male to resting gonads, consisting of 3499 which were comparatively upregulated in males and 1264 which were downregulated in males. Six hundred-ninteen DEGs between male and hermaphroditic gonads were identified, with 518 DEGs more strongly expressed in hermaphrodites and 101 more strongly expressed in males. GO (Gene Ontology) and KEGG pathway analyses revealed that various biological functions and processes, including functions related to the endocrine system, oocyte meiosis, carbon metabolism, and the cell cycle, were involved in regulating gonadal development and gametogenesis in T. squamosa . Testis-specific serine/threonine kinases 1 (TSSK1), TSSK4, TSSK5, Doublesex- and mab-3-related transcription factor 1 (DMRT1), SOX, Sperm surface protein 17 (SP17) and other genes were involved in male gonadal development in Tridacna squamosal. Both spermatogenesis- (TSSK4, spermatogenesis-associated protein 17, spermatogenesis-associated protein 8, sperm motility kinase X, SP17) and oogenesis-related genes (zona pellucida protein, Forkhead Box L2, Vitellogenin, Vitellogenin receptor, 5-hydroxytryptamine, 5-hydroxytryptamine receptor) were simultaneously highly expressed in the hermaphroditic gonad to maintain the hermaphroditism of T. squamosa . Conclusion All these results from our study will facilitate better understanding of the molecular mechanisms underlying giant clam gonad development and gametogenesis, which can provided a base on obtaining excellent gametes during the seed production process for giant clams.

Eggs in a dish \"Epigenetic reprogramming is key to making the next generation,\" says Mitinori Saitou, a stem-cell biologist at Kyoto University in Japan, and a co-author of the paper (Y. Murase etai. [...]in addition to its technical difficulty, growing eggs and sperm in a dish - called in vitro gametogenesis - would carry weighty social and ethical questions. Furthermore, the epigenome affects gene activity, helping cells with identical DNA sequences to take on unique identities.