Clonal gametogenesis is triggered by intrinsic stimuli in the hybrids germ cells but is dependent on sex differentiation

Interspecific hybridization may trigger the transition from sexual reproduction to asexuality, but mechanistic reasons for such a change in a hybrids reproduction are poorly understood. Gametogenesis of many asexual hybrids involves a stage of premeiotic endoreduplication (PMER), when gonial cells duplicate chromosomes and subsequent meiotic divisions involve bivalents between identical copies, leading to production of clonal gametes. Here, we investigated the triggers of PMER and whether its induction is linked to intrinsic stimuli within a hybrids gonial cells or whether it is regulated by the surrounding gonadal tissue. We investigated gametogenesis in the Cobitis taenia hybrid complex, which involves sexually reproducing species (Cobitis elongatoides and C. taenia) as well as their hybrids, where females reproduce clonally via PMER while males are sterile. We transplanted spermatogonial stem cells (SSCs) from C. elongatoides and triploid hybrid males into embryos of sexual species and of asexual hybrid females, respectively, and observed their development in an allospecific gonadal environment. Sexual SSCs underwent regular meiosis and produced normally reduced gametes when transplanted into clonal females. On the other hand, the hybrids SSCs lead to sterility when transplanted into sexual males, but maintained their ability to undergo asexual development (PMER) and production of clonal eggs, when transplanted into sexual females. This suggests that asexual gametogenesis is under complex control when somatic gonadal tissue indirectly affects the execution of asexual development by determining the sexual differentiation of stem cells and once such cells develop to female phenotypes, hybrid germ cells trigger the PMER from their intrinsic signals.

Standardization of fertility preservation discussion amongst pediatric oncology and bone marrow transplant patients.

10051 Background: As treatment for pediatric malignancies improves long term survival, physicians are shifting focus to late effects of therapy such as infertility. Currently, options for fertility preservation include cryopreservation of mature oocytes, sperm, and gonadal tissue, although barriers remain present. Within our division, we lacked a standard approach to discussing fertility preservation options. Methods: Records from 474 pediatric patients with new oncologic diagnoses at CMH from 2014-2020 were retrospectively reviewed. We evaluated the frequency that reproductive health discussions were documented in pubertal males and females requiring chemotherapy or radiation treatment. We implemented a standard fertility preservation note and patient handouts, then surveyed our department to identify diagnoses that place patients at risk for infertility and barriers to formalized fertility consultations. We then provided educational sessions to address these barriers with pre- and post-evaluation to measure efficacy. Our longitudinal assessment, encompassing multiple points of intervention, was compared to results from previous chart review (2010-2013). Results: Of 474 patients diagnosed between 2014-2020, 175 (90 females, 85 males) warranted a fertility discussion per inclusion criteria. 61 (67.8%) females received a fertility discussion and of those 8 (8.9%) completed oocyte or gonadal tissue preservation, all between 2017-2020. 52 (61.2%) males received a fertility discussion and 20 (23.5%) completed sperm cryopreservation, with even distribution pattern between 2014-2020. Following implementation of an electronic fertility consult process and standardized fertility preservation documentation, there was an increase in documented fertility discussions from 30% in 2014 to 63.6% in 2020. Internal department survey responses identified a lack of comfort with knowing fertility preservation options available and diagnoses that should prompt this conversation. Education sessions with pre- and post-provider assessment demonstrated more comfort discussing fertility preservation (average score increase from 3.44 to 4.33) and knowledge regarding diagnoses at higher risk of infertility (average score increase from 3.67 to 4.33). Conclusions: Integration of a standardized fertility preservation process and addressing barriers identified within our division have led to a 33.6% increase in fertility discussions over the last 6 years. While the data shows a promising increase in oocyte and ovarian tissue preservation, sperm banking completion rates remained unchanged. Further steps include incorporation of an automated fertility consultation order into electronic chemotherapy orders, hospital-wide identification of other high-risk patient populations, and continued education of patient, families, and the health care team.

Fertility Preservation for Prepubertal Patients at Risk of Infertility: Present Status and Future Perspectives

The increasing cure rate of cancer has led to a vast population of survivors having to face the late adverse effects of oncological treatments, with fertility impairment being one of the most sensitive issues for patients. Different options to preserve the fertility of adult patients are routinely used in clinical practice. However, fertility preservation strategies for prepubertal patients at risk of infertility are limited to the cryopreservation of immature gonadal tissue. In recent decades, many research efforts have been focused on the future use of cryopreserved gonadal tissue. This review discusses the common status of fertility preservation measures for pediatric patients undergoing gonadotoxic treatment, focusing especially on the challenges that remain to be solved in order to implement this fundamental service.

Hot Topics on Fertility Preservation for Women and Girls—Current Research, Knowledge Gaps, and Future Possibilities

Fertility preservation is a novel clinical discipline aiming to protect the fertility potential of young adults and children at risk of infertility. The field is evolving quickly, enriched by advances in assisted reproductive technologies and cryopreservation methods, in addition to surgical developments. The best-characterized target group for fertility preservation is the patient population diagnosed with cancer at a young age since the bulk of the data indicates that the gonadotoxicity inherent to most cancer treatments induces iatrogenic infertility. Since improvements in cancer therapy have resulted in increasing numbers of long-term survivors, survivorship issues and the negative impact of infertility on the quality of life have come to the front line. These facts are reflected in an increasing number of scientific publications referring to clinical medicine and research in the field of fertility preservation. Cryopreservation of gametes, embryos, and gonadal tissue has achieved quality standards for clinical use, with the retrieval of gonadal tissue for cryopreservation being currently the only method feasible in prepubertal children. Additionally, the indications for fertility preservation beyond cancer are also increasing since a number of benign diseases and chronic conditions either require gonadotoxic treatments or are associated with premature follicle depletion. There are many remaining challenges, and current research encompasses clinical health care and caring sciences, ethics, societal, epidemiological, experimental studies, etc.

Fertility preservation: should we reconsider the terminology?

The term ‘fertility preservation’ embraces techniques that are actually mostly based on gamete and gonadal tissue cryopreservation. While the efficiency of these techniques in terms of live births remains difficult to establish, it is remarkable that this ambiguous terminology is routinely used and seems currently well accepted. In order to limit false hopes about the real chances of truly preserving fertility, our medical community should discuss qualifying the term ‘fertility preservation’. ‘Gamete or gonadal tissue cryopreservation’ could appear as a more unambiguous and realistic term. However, it probably captures only a segment of a more global ‘fertility preservation’ process. Discussing how and when to use which terminology, and even finding a more realistic and unifying term, should be further explored.

Medusophagy in northern fulmars Fulmarus glacialis: feeding behaviour observed at sea

Several marine animals prey extensively on jellyfish in spite of the low energy contents of this type of prey. Northern Fulmars Fulmarus glacialis observed in the Barents Sea feeding on medusae of lion’s mane jellies Cyanea capillata fed from the underside of the jellyfish, eagerly ingesting gonadal tissue as well as oral arms and tentacles, while the gelatinous tissue of the umbrella apparently was neglected by the birds. Gonads, arms and tentacles have about five times higher energetic contents than the tissue of the bell, approaching that of some species of fish. Aggressive defence of their prey and a continued feeding on jellyfish in the presence of discarded fish offal indicated jellyfish to be more than a second choice food for Northern Fulmars. The observations clearly showed that the Fulmars did not primarily feed on organisms associated with jellyfish. Their abundance and slow swimming make jellyfish an easily available prey. Scyphozoan cnidarians may be more important to pelagic seabirds than generally thought.