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1. Reproductive genomics of the mouse: implications for human fertility and infertility

   https://doi.org/10.1242/dev.201313  

   Garretson, Alexis; Dumont, Beth L.; Handel, Mary Ann (April 2023, Development)

   Eve, Alex (Ed.)

   Genetic analyses of mammalian gametogenesis and fertility have the potential to inform about two important and interrelated clinical areas: infertility and contraception. Here, we address the genetics and genomics underlying gamete formation, productivity and function in the context of reproductive success in mammalian systems, primarily mouse and human. Although much is known about the specific genes and proteins required for meiotic processes and sperm function, we know relatively little about other gametic determinants of overall fertility, such as regulation of gamete numbers, duration of gamete production, and gamete selection and function in fertilization. As fertility is not a binary trait, attention is now appropriately focused on the oligogenic, quantitative aspects of reproduction. Multiparent mouse populations, created by complex crossing strategies, exhibit genetic diversity similar to human populations and will be valuable resources for genetic discovery, helping to overcome current limitations to our knowledge of mammalian reproductive genetics. Finally, we discuss how what we know about the genomics of reproduction can ultimately be brought to the clinic, informing our concepts of human fertility and infertility, and improving assisted reproductive technologies. 

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2. Maternal effect senescence and caloric restriction interact to affect fitness through changes in life history timing

   https://doi.org/10.1111/1365-2656.14220  

   Hernández, Christina M; van_Daalen, Silke F; Liguori, Alyssa; Neubert, Michael G; Caswell, Hal; Gribble, Kristin E (January 2025, Journal of Animal Ecology)

   Abstract Environmental factors and individual attributes, and their interactions, impact survival, growth and reproduction of an individual throughout its life. In the clonal rotiferBrachionus, low food conditions delay reproduction and extend lifespan. This species also exhibits maternal effect senescence; the offspring of older mothers have lower survival and reproductive output. In this paper, we explored the population consequences of the individual‐level interaction of maternal age and low food availability.We built matrix population models for both ad libitum and low food treatments, in which individuals are classified both by their age and maternal age. Low food conditions reduced population growth rate () and shifted the population structure to older maternal ages, but did not detectably impact individual lifetime reproductive output.We analysed hypothetical scenarios in which reduced fertility or survival led to approximately stationary populations that maintained the shape of the difference in demographic rates between the ad libitum and low food treatments. When fertility was reduced, the populations were more evenly distributed across ages and maternal ages, while the lower‐survival models showed an increased concentration of individuals in the youngest ages and maternal ages.Using life table response experiment analyses, we compared populations grown under ad libitum and low food conditions in scenarios representing laboratory conditions, reduced fertility and reduced survival. In the laboratory scenario, the reduction in population growth rate under low food conditions is primarily due to decreased fertility in early life. In the lower‐fertility scenario, contributions from differences in fertility and survival are more similar, and show trade‐offs across both ages and maternal ages. In the lower‐survival scenario, the contributions from decreased fertility in early life again dominate the difference in .These results demonstrate that processes that potentially benefit individuals (e.g. lifespan extension) may actually reduce fitness and population growth because of links with other demographic changes (e.g. delayed reproduction). Because the interactions of maternal age and low food availability depend on the population structure, the fitness consequences of an environmental change can only be fully understood through analysis that takes into account the entire life cycle. 

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3. Sexual dimorphism in the meiotic requirement for PRDM9: A mammalian evolutionary safeguard

   https://doi.org/10.1126/sciadv.abb6606  

   Powers, Natalie R.; Dumont, Beth L.; Emori, Chihiro; Lawal, Raman Akinyanju; Brunton, Catherine; Paigen, Kenneth; Handel, Mary Ann; Bolcun-Filas, Ewelina; Petkov, Petko M.; Bhattacharyya, Tanmoy (October 2020, Science Advances)

   null (Ed.)

   In many mammals, genomic sites for recombination are determined by the histone methyltransferase PRMD9. Some mouse strains lacking PRDM9 are infertile, but instances of fertility or semifertility in the absence of PRDM9 have been reported in mice, canines, and a human female. Such findings raise the question of how the loss of PRDM9 is circumvented to maintain fertility. We show that genetic background and sex-specific modifiers can obviate the requirement for PRDM9 in mice. Specifically, the meiotic DNA damage checkpoint protein CHK2 acts as a modifier allowing female-specific fertility in the absence of PRDM9. We also report that, in the absence of PRDM9, a PRDM9-independent recombination system is compatible with female meiosis and fertility, suggesting sex-specific regulation of meiotic recombination, a finding with implications for speciation. 

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4. Sperm competitive advantage of a rare mitochondrial haplogroup linked to differential expression of mitochondrial oxidative phosphorylation genes

   https://doi.org/10.1111/jeb.13536  

   Zeh, Jeanne A.; Zawlodzki, Maya A.; Bonilla, Melvin M.; Su‐Keene, Eleanor J.; Padua, Michael V.; Zeh, David W. (September 2019, Journal of Evolutionary Biology)

   Abstract Maternal inheritance of mitochondria creates a sex‐specific selective sieve through which mitochondrial mutations harmful to males but not females accumulate and contribute to sexual differences in longevity and disease susceptibility. Because eggs and sperm are under disruptive selection, sperm are predicted to be particularly vulnerable to the genetic load generated by maternal inheritance, yet evidence for mitochondrial involvement in male fertility is limited and controversial. Here, we exploit the coexistence of two divergent mitochondrial haplogroups (A and B2) in a Neotropical arachnid to investigate the role of mitochondria in sperm competition. DNA profiling demonstrated that B2‐carrying males sired more than three times as many offspring in sperm competition experiments than A males, and this B2 competitive advantage cannot be explained by female mitochondrial haplogroup or male nuclear genetic background. RNA‐Seq of testicular tissues implicates differential expression of mitochondrial oxidative phosphorylation (OXPHOS) genes in the B2 competitive advantage, including a 22‐fold upregulation ofatp8in B2 males. Previous comparative genomic analyses have revealed functionally significant amino acid substitutions in differentially expressed genes, indicating that the mitochondrial haplogroups differ not only in expression but also in DNA sequence and protein functioning. However, mitochondrial haplogroup had no effect on sperm number or sperm viability, and, when females were mated to a single male, neither male haplogroup, female haplogroup nor the interaction between male/female haplogroup significantly affected female reproductive success. Our findings therefore suggest that mitochondrial effects on male reproduction may often go undetected in noncompetitive contexts and may prove more important in nature than is currently appreciated. 

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5. Emotion, embodiment, and reproductive colonialism in the global human egg trade

   https://doi.org/10.1111/gwao.12637  

   Tober, Diane; Kroløkke, Charlotte (March 2021, Gender, Work & Organization)

   null (Ed.)

   In the transnational fertility industry, individuals have differently positioned bodies, ranked by race, class, education, socioeconomic status, gender, and citizenship. Different forms of labor support the transnational fertility market, bringing geopolitical, and social inequities to the fore. While some people need wombs, eggs, or sperm to create their families—and have the means to pay for third‐party reproductive services—others emerge as suppliers of reproductive labor, and still others as coordinators or service agents in the international fertility industry. Building upon contemporary feminist social science and postcolonial research on reproductive travel and labor, this article explores three intersecting components: the forces that influence reproductive travel and cross‐border egg donation; how emotion and meaning are framed in clinical settings to recruit a young, healthy, able‐bodied workforce; and the embodied experiences of women who travel across borders to provide eggs for pay. Drawing upon donor and professional interviews, and multisited online and ethnographic fieldwork in fertility clinics, we explore the linkages between emotional choreography and the creation of a bioavailable workforce for the global fertility trade. Here, we examine how local and cross‐border egg provision illuminate global reproductive hierarchies—what we call “reproductive colonialism”—in transnational reproduction. 

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