Lessons from biodiversity--the value of nontraditional species to advance reproductive science, conservation, and human health

Arthropods to Eutherians: A Historical and Contemporary Comparison of Sparse Prenatal Microbial Communities Among Animalia Species

Since the advent of next-generation sequencing, investigators worldwide have sought to discern whether a functional and biologically or clinically relevant prenatal microbiome exists. One line of research has led to the hypothesis that microbial DNA detected in utero/in ovo or prior to birth/hatching is a result of contamination and does not belong to viable and functional microbes. Many of these preliminary evaluations have been conducted in humans, mice, and nonhuman primates due to sample and specimen availability. However, a comprehensive review of the literature across animal species suggests organisms that maintain an obligate relationship with microbes may act as better models for interrogating the selective pressures placed on vertical microbial transfer over traditional laboratory species. To date, studies in humans and viviparous laboratory species have failed to illustrate the clear presence and transfer of functional microbes in utero. Until a ground truth regarding the status and relevance of prenatal microbes can be ascertained, it is salient to conduct parallel investigations into the prevalence of a functional prenatal microbiome across the developmental lifespan of multiple organisms in the kingdom Animalia. This comprehensive understanding is necessary not only to determine the role of vertically transmitted microbes and their products in early human health but also to understand their full One Health impact. This review is among the first to compile such comprehensive primary conclusions from the original investigator's conclusions, and hence collectively illustrates that prenatal microbial transfer is supported by experimental evidence arising from over a long and rigorous scientific history encompassing a breadth of species from kingdom Animalia.

Development of decellularization protocols for female cat reproductive organs

Decellularization is an innovative method to create natural scaffolds by removing all cellular materials while preserving the composition and three-dimensional ultrastructure of the extracellular matrix (ECM). The obtention of decellularized reproductive organs in cats might facilitate the development of assisted reproductive techniques not only in this species but also in other felids. The aim was to compare the efficiency of three decellularization protocols on reproductive organs (ovary, oviduct, and uterine horn) in domestic cats. The decellularization protocol involved 0.1% sodium dodecyl sulfate and 1%Triton X-100. Protocol 1 (P1) entailed 2-cycles of decellularization using these detergents. Protocol 2 (P2) was like P1 but included 3-cycles. Protocol 3 (P3) was similar to P2, with the addition of deoxyribonuclease incubation. Reproductive organs from nine cats were separated into two sides. One side served as the control (non-decellularized organ) while the contralateral side was the treated group (decellularized organ). The treated organs were subdivided into 3 groups (n = 3 per group) for each protocol. Both control and treated samples were analyzed for DNA content, histology (nuclear and ECM (collagen, elastin, and glycosaminoglycans (GAGs)) density), ultrastructure by electron microscopy, and cytotoxicity. The results of the study showed that P3 was the only protocol that displayed no nucleus residue and significantly reduced DNA content in decellularized samples (in all the studied organs) compared to the control (P < 0.05). The ECM content in the ovaries remained similar across all protocols compared with controls (P > 0.05). However, elastic fibers and GAGs decreased in decellularized oviducts (P < 0.05), while collagen levels remained unchanged (P > 0.05). Regarding the uterus, the ECM content decreased in decellularized uterine horns from P3 (P < 0.05). Electron microscopy revealed that the microarchitecture of the decellularized samples was maintained compared to controls. The decellularized tissues, upon being washed for 24 h, showed cytocompatibility following co-incubation with sperm. In conclusion, when comparing different decellularization methods, P3 proved to be the most efficient in removing nuclear material from reproductive organs compared to P1 and P2. P3 demonstrated its success in decellularizing ovarian samples by significantly decreasing DNA content while maintaining ECM components and tissue microarchitecture. However, P3 was less effective in maintaining ECM contents in decellularized oviducts and uterine horns.

Interaction between epidermal growth factor receptor and C-C motif chemokine receptor 2 in the ovulatory cascade

The epidermal growth factor receptor (EGFR) signaling pathway is one of the main pathways responsible for propagating the luteinizing hormone (LH) signal throughout the cumulus cells and the oocyte. Recently, we have proposed the C-C motif chemokine receptor 2 (CCR2) and its main ligand (monocyte chemoattractant protein-1, MCP1) as novel mediators of the ovulatory cascade. Our previous results demonstrate that the gonadotropins (GNT), amphiregulin (AREG), and prostaglandin E2 (PGE2) stimulation of periovulatory gene mRNA levels occurs, at least in part, through the CCR2/MCP1 pathway, proposing the CCR2 receptor as a novel mediator of the ovulatory cascade in a feline model. For that purpose, feline cumulus-oocyte complexes (COCs) were cultured in the presence or absence of an EGFR inhibitor, recombinant chemokine MCP1, and gonadotropins [as an inducer of cumulus-oocyte expansion (C-OE), and oocyte maturation] to further assess the mRNA expression of periovulatory key genes, C-OE, oocyte nuclear maturation, and steroid hormone production. We observed that MCP1 was able to revert the inhibition of AREG mRNA expression by an EGFR inhibitor within the feline COC. In accordance, the confocal analysis showed that the GNT-stimulated hyaluronic acid (HA) synthesis, blocked by the EGFR inhibitor, was recovered by the addition of recombinant MCP1 in the C-OE culture media. Also, MCP1 was able to revert the inhibition of progesterone (P4) production by EGFR inhibitor in the C-OE culture media. Regarding oocyte nuclear maturation, recombinant MCP1 could also revert the inhibition triggered by the EGFR inhibitor, leading to a recovery in the percentage of metaphase II (MII)-stage oocytes. In conclusion, our results confirm the chemokine receptor CCR2 as a novel intermediate in the ovulatory cascade and demonstrate that the EGFR/AREG and the CCR2/MCP1 signaling pathways play critical roles in regulating feline C-OE and oocyte nuclear maturation, with CCR2/MCP1 signaling pathway being downstream EGFR/AREG pathway within the ovulatory cascade.

Challenges on the Development of Biodiversity Biobanks: The Living Archives of Biodiversity

Biodiversity biobanks or ex situ biodiversity biorepositories tend to receive less attention compared with their biomedical counterparts. In this review, we highlight the necessity for these biorepositories by presenting their significant role in health, biodiversity, linking of big data, other translational research, and biodiversity conservation efforts. Moreover, the significant challenges in developing and maintaining biodiversity biobanks based on successful biobanks in some megadiverse developing countries are examined to provide insights into what needs to be done and what can be improved by up-and-coming biodiversity biobanks. These challenges include lack of financial support and political will; availability of experts; development of standard policies; and information management system. In addition, issues regarding access and benefit sharing and Digital Sequence Information must be addressed by biodiversity biobanks.

An automated modular open-technology device to measure and adjust concentration of aquatic sperm samples for cryopreservation

Repositories for aquatic germplasm are essential for safeguarding valuable genetic diversity for species relevant to aquaculture, biomedical research, and conservation. Development of aquatic germplasm repositories is impeded by a lack of standardization within laboratories and across the research community. Protocols for cryopreservation are often developed ad hoc and without close attention to variables, such as cell concentration, that strongly affect the success and reproducibility of cryopreservation. The wide dissemination and use of specialized tools and devices as open hardware can improve processing reliability and save costs. The goal of the present work was to develop and prototype a modular and open-technology approach to help to standardize the cell concentration of germplasm samples prior to cryopreservation. The specific objectives were to: 1) design and fabricate prototypes of the automated concentration measurement and adjustment system (CMAS), incorporating custom peristaltic pumps and optical evaluation modules, and 2) evaluate the performance of the CMAS with biological samples. Linear regression models were obtained for estimation of aquatic sperm concentration >108 cells/mL and for algae concentration > (3 × 105) cells/mL. Algae were diluted with extender medium by an automated process, resulting in a dilution precision of ±12.6% and ±6.7% in two trials, attaining means of 89% and 71% of the target cell concentration. The development of the CMAS as open technology can provide opportunities for community-level standardization in cryopreservation of aquatic germplasm and can invite new users, makers, and developers into the open-technology community. This will increase the reach and capabilities of much-needed aquatic germplasm repositories.

The Use of Commercial Microvolume Techniques for Feline Oocyte Vitrification

This project aimed to compare the three most popular commercial oocyte vitrification techniques to determine their suitability for the vitrification of felid germlines in rescue and conservation programs. The present study aimed to determine the viability and developmental competence of feline oocytes after IVM and vitrification using a commercial vitrification method. In the first experiment, oocytes were vitrified after in vitro maturation (IVM) using the Kitazato, Cryotech, and Vitrolife methods. The oocytes were stained with fluorescein diacetate and ethidium bromide to evaluate their viability. The differences between Vitrolife and the control, Cryotech and Kitazato were statistically significant (p < 0.05), and between the control and Kitazato, were highly significant (p < 0.01). There were no significant differences between the control and Cryotech, Vitrolife and Cryotech, or Kitazato and Vitrolife. In the second part of the experiment, oocytes, after IVM and vitrification using three commercial methods, were subjected to fertilization. After vitrification, IVF was performed. We observed 35% of embryonic divisions in the group where Vitrolife and Kitazato media were used and 45% in the control group. In the presented experiment, vitrification with Vitrolife media gave slightly better results for survival and fertilization, while in the case of emergency protocol vitrification, all of the above methods may be useful to protect material derived from valuable wild felids.

Longitudinal patterns in progesterone metabolites in pregnant and non-pregnant Steller sea lions (Eumetopias jubatus)

Similar to the several pinniped and a few terrestrial carnivore species, the Steller sea lion has a seasonal synchronized mating scheme enabled by a female reproductive cycle that includes embryonic diapause, delayed implantation, and pseudopregnancy (a state in which the corpus luteum produces progesterone for approximately as long as in pregnant females). Due to this, circulating systemic progesterone concentrations cannot be used to differentiate pregnant and nonpregnant females during early gestation. With the use of advanced measurement technologies such as liquid chromatography tandem mass spectrometry (LC-MS/MS) additional steroid hormones are measurable which can provide additional information on the endocrine pathways throughout gestation. Our objectives were to further characterize endocrine patterns in female Steller sea lion pregnancy by 1) quantifying longitudinal profiles of hormone metabolites in pregnant and non-pregnant female sera, and 2) evaluating hormone profiles to identify pregnant animals within the early stage of gestation. Three gestation stages were delineated based on what is believed to be the period of implantation (September-October): EARLY (August- November), MID (December-February), and LATE (March to May). Five steroids, Progesterone (P₄), 5α-dihydroprogesterone (DHP), 17αOH-progesterone (17OHP), 20αOH-progesterone (20OHP), and androstenedione (A₄), were detected in both pregnant and non-pregnant animals. A significant difference in P₄ concentrations was measured between EARLY and MID gestation (p ≤ 0.01) in both pregnant and non-pregnant animals. During MID gestation there was a significant difference (p ≤ 0.05) between pregnant and non-pregnant animals in all pregnanes measured. Significant patterns of correlation between P₄ and 17OHP and between P₄ and DHP were detected during EARLY and MID gestation in non-pregnant animals. While those significant correlations also exist in EARLY pregnant animals, this pattern was lost by MID gestation. This loss of correlation suggests a potential shift in progesterone metabolism from ovarian to alternative tissue (e.g. fetal gonads or adrenal glands) by MID gestation in Steller sea lions. We were unable to identifying a steroid hormone biomarker capable of differentiating pseudopregnancy from pregnant animals and conclude that such a biomarker likely falls outside of the traditional progesterone metabolic pathway.

Resurrecting biodiversity: advanced assisted reproductive technologies and biobanking

Biodiversity is defined as the presence of a variety of living organisms on the Earth that is essential for human survival. However, anthropogenic activities are causing the sixth mass extinction, threatening even our own species. For many animals, dwindling numbers are becoming fragmented populations with low genetic diversity, threatening long-term species viability. With extinction rates 1000-10,000 times greater than natural, ex situ and in situ conservation programmes need additional support to save species. The indefinite storage of cryopreserved (-196°C) viable cells and tissues (cryobanking), followed by assisted or advanced assisted reproductive technology (ART: utilisation of oocytes and spermatozoa to generate offspring; aART: utilisation of somatic cell genetic material to generate offspring), may be the only hope for species' long-term survival. As such, cryobanking should be considered a necessity for all future conservation strategies. Following cryopreservation, ART/aART can be used to reinstate lost genetics back into a population, resurrecting biodiversity. However, for this to be successful, species-specific protocol optimisation and increased knowledge of basic biology for many taxa are required. Current ART/aART is primarily focused on mammalian taxa; however, this needs to be extended to all, including to some of the most endangered species: amphibians. Gamete, reproductive tissue and somatic cell cryobanking can fill the gap between losing genetic diversity today and future technological developments. This review explores species prioritisation for cryobanking and the successes and challenges of cryopreservation and multiple ARTs/aARTs. We here discuss the value of cryobanking before more species are lost and the potential of advanced reproductive technologies not only to halt but also to reverse biodiversity loss.

Lay summary

The world is undergoing its sixth mass extinction; however, unlike previous events, the latest is caused by human activities and is resulting in the largest loss of biodiversity (all living things on Earth) for 65 million years. With an extinction rate 1000-10,000-fold greater than natural, this catastrophic decline in biodiversity is threatening our own survival. As the number of individuals within a species declines, genetic diversity reduces, threatening their long-term existence. In this review, the authors summarise approaches to indefinitely preserve living cells and tissues at low temperatures (cryobanking) and the technologies required to resurrect biodiversity. In the future when appropriate techniques become available, these living samples can be thawed and used to reinstate genetic diversity and produce live young ones of endangered species, enabling their long-term survival. The successes and challenges of genome resource cryopreservation are discussed to enable a move towards a future of stable biodiversity.

Altered Expression of Protamine-like and Their DNA Binding Induced by Cr(VI): A Possible Risk to Spermatogenesis?

Chromium (VI) is the most dangerous oxidation state among the stable forms of chromium. In this work, we evaluated the effect of exposing Mytilus galloprovincialis for 24 h to 1, 10, and 100 nM chromium (VI) on the properties of Protamine-like (PLs) and their gene levels in the gonads. Specifically, we analyzed, by AU-PAGE and SDS-PAGE, PLs extracted from unexposed and exposed mussels. In addition, via EMSA, we evaluated the ability of PLs to bind DNA and also verified their potential to protect DNA from oxidative damage. Finally, we assessed possible alterations in gonadal expression of mt10, hsp70, and genes encoding for PLs-II/PL-IV and PL-III. We found that for all experimental approaches the most relevant alterations occurred after exposure to 1 nM Cr(VI). In particular, a comigration of PL-II with PL-III was observed by SDS-PAGE; and a reduced ability of PLs to bind and protect DNA from oxidative damage was recorded. This dose of chromium (VI) exposure was also the one that produced the greatest alterations in the expression of both mt10 and PL-II/PL-IV encoding genes. All of these changes suggest that this dose of chromium (VI) exposure could affect the reproductive health of Mytilus galloprovincialis.

Biological Effects of Non-Ionizing Electromagnetic Fields at 27 GHz on Sperm Quality of Mytilus galloprovincialis

Recently, an increasing use of wireless internet technologies has been demonstrated. The devices which use these technologies emit in new spectral regions an electromagnetic radiation (EMF) which could interact with the male reproductive system. The aim of this study was to investigate in vitro the effect of electromagnetic fields at 27 GHz on sperm quality in Mytilus galloprovincialis. Sperm samples were collected from sexually mature males of M. galloprovincialis and placed in seawater. Once we evaluated the number and quality of spermatozoa, sperm cells were exposed to electromagnetic fields radiated by a pyramidal horn antenna. The effect of exposure was evaluated after 10, 20, 30, 40 and 60 min by a light microscope and using an Eosin test. Ten replications were performed for each time series, and statistical analysis was carried out by t-test. Sperm motility decreased after 10 min of exposure, and after 30 min most of the spermatozoa were immobile and not vital. This study provides useful data on the potential ecological impact of the high-band 5G on animal fertility, the effect of which is currently under investigation.

Recent Progress in Spermatology Contributing to the Knowledge and Conservation of Rare and Endangered Species

There is a remarkable diversity in the animal kingdom regarding mechanisms underlying the production, maturation, structure, and function of sperm cells. Spermatology studies contribute to the knowledge of species diversity and also provide information about individual or population fitness. Furthermore, this fundamental research is required before collected spermatozoa can be used for conservation breeding, including assisted reproduction and cryobanking. This article aims to (a) review the most recent knowledge on sperm morphology and function in wild animal species, (b) analyze how this knowledge can be used to save species in their natural habitat or ex situ, and (c) propose future scientific directions in wildlife spermatology that could positively impact animal conservation. Variations in sperm structure and performance within and between species have multiple origins and significance. This collective body of knowledge enables the design and implementation of conservation strategies and action plans that integrate several disciplines. Expected final online publication date for the Annual Review of Animal Biosciences, Volume 10 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Sex, drugs and rock iguanas: testicular dynamics and plasma testosterone concentrations could predict optimal semen collection times in Cyclura

Iguanas are the most endangered family of reptiles, with 77% categorised as threatened or near threatened. Further, Cyclura is the most endangered reptile genus, with all 12 species considered threatened. Therefore, it is vital that we develop assisted reproductive technologies for Cyclura spp. to enhance their conservation efforts. The goals of this study were to collect semen, and to measure testicle size and testosterone concentrations in Grand Cayman rock iguana hybrids (Cyclura lewisi×nubila (CLN)) and rhinoceros rock iguanas (Cyclura cornuta (CC)). A prospective longitudinal study was performed in 9.0 CLN and 9.0 CC during their reproductive season in southern Florida (February-July). Serial testicle ultrasound measurements and plasma testosterone concentrations were collected monthly. Testicle measurements (length (L), width (W), height (H)) were collected and testicle volume (V) was estimated using the equation V=0.52(LW2). There were significant differences in testicle L, W, H and V for both species. Testicle size peaked for CLN and CC in April and May respectively. Plasma testosterone concentrations increased from baseline during February, March and April in CLN and in March, April and May in CC. Ultrasound testicle measurements could be used to predict when to collect semen in these seasonally monocyclic iguanas.

Morphology of the genital organs of male and female giant anteaters (Myrmecophaga tridactyla)

BACKGROUND

The giant anteater belongs to the supraorder Xenarthra which occupies a systematically isolated position among placental mammals. The species is categorized as Vulnerable by the International Union for Conservation of Nature, and understanding its reproductive characteristics is critical for future conservation efforts.

METHODS

Gross and microscopic anatomy of the genital organs of 23 male and 21 female adult and young roadkill giant anteaters in Brazil were studied.

RESULTS

Male giant anteaters presented a short conical penis, intraabdominal testes, and prostate, vesicular and bulbourethral glands. A tubular remnant of the partially fused Müllerian ducts extended from the seminal colliculus through the prostate gland, continued cranially in the genital fold, bifurcated, and attached with one elongation each to the left and right epididymal corpus. The structure presented a total length of up to 10 cm and contained a yellowish liquid in its lumen. Histologically, the caudal section of this structure resembled the female vagina, the middle portion corresponded to the uterus, and the extensions showed characteristics of uterine tubes. In adult female giant anteaters, ovoid ovaries with occasional seminiferous cord-like structures were observed. The animals possessed a simple uterus, which was directly continuous with the vaginal canal. The caudal portion of the vagina had two lumina, separated by a longitudinal septum and opening into two apertures into the vaginal vestibule, cranial to the urethral opening. In the urethral and the lateral vestibular wall, glandular structures with characteristics of male prostate and bulbourethral glands, respectively, were found. The vestibule opened through a vertical vulvar cleft to the exterior. A pair of well-differentiated Wolffian ducts with a central lumen originated ventrally at the vaginal opening into the vestibule and passed in a cranial direction through the ventral vaginal and uterine wall. Each duct extended highly coiled along the ipsilateral uterine tube until the lateral pole of the ovaries where it merged with the rete ovarii.

DISCUSSION

The reproductive morphology of giant anteaters reveals characteristics shared with other Xenarthrans: intraabdominal testes, a simple uterus, and a double caudal vagina. The persistence of well-differentiated genital ducts of the opposite sex in both males and females, however, singles them out among other species. These structures are the results of an aberration during fetal sexual differentiation and possess secretory functions. The possibility of a pathological degeneration of these organs should be considered in reproductive medicine of the species.

CONCLUSION

Knowledge of the unique reproductive characteristics of the giant anteater is essential for future reproductive management of the species. Additionally, further research on the peculiarities of the persisting genital duct structures might help to understand sexual differentiation in placental mammals in general.

C-C motif chemokine receptor 2 as a novel intermediate in the ovulatory cascade

Expression of immune function genes within follicle cells has been reported in ovaries from many species. Recent work from our laboratory showed a direct effect of the monocyte chemoattractant protein 1/C-C motif chemokine receptor 2 system within the feline cumulus oocyte complex, by increasing the mRNA levels of key genes involved in the ovulatory cascade in vitro. Studies were designed to evaluate if C-C motif chemokine receptor 2 acts as a novel mediator of the ovulatory cascade in vitro. Therefore, feline cumulus oocyte complexes were cultured in the presence or absence of a highly selective C-C motif chemokine receptor 2 antagonist together with known inducers of cumulus-oocyte expansion and/or oocyte maturation to assess mRNA expression of key genes related to periovulatory events in other species as well as oocyte maturation. Also, the effects of recombinant monocyte chemoattractant protein 1 on spontaneous or gonadotrophin-induced oocyte maturation were assessed. This is an in vitro system using isolated cumulus oocyte complexes from feline ovaries. The present study reveals the modulation of several key ovulatory genes by a highly selective C-C motif chemokine receptor 2 antagonist. However, this antagonist was not enough to block the oocyte maturation induced by gonadotropins or amphiregulin. Nonetheless, recombinant monocyte chemoattractant protein 1 had a significant effect on spontaneous oocyte maturation, increasing the percentage of metaphase II stage oocytes in comparison to the control. This is the first study in any species to establish C-C motif chemokine receptor 2 as a mediator of some actions of the mid-cycle gonadotrophin surge.

The steroid metabolome of pregnancy, insights into the maintenance of pregnancy and evolution of reproductive traits

Modes of mammalian reproduction are diverse and not always conserved among related species. Progesterone is universally required to supports pregnancy but sites of synthesis and metabolic pathways vary widely. The steroid metabolome of mid-to late gestation was characterized, focusing on 5α-reduced pregnanes in species representing the Perissodactyla, Cetartiodactyla and Carnivora using mass spectrometry. Metabolomes and steroidogenic enzyme ortholog sequences were used in heirarchial analyses. Steroid metabolite profiles were similar within orders, whales within cetartiodactyls for instance, but with notable exceptions such as rhinoceros clustering with goats, and tapirs with pigs. Steroidogenic enzyme sequence clustering reflected expected evolutionary relationships but once again with exceptions. Human sequences (expected outgroups) clustered with perissodactyl CYP11A1, CYP17A1 and SRD5A1 gene orthologues, forming outgroups only for HSD17B1 and SRD5A2. Spotted hyena CYP19A1 clustered within the Perissodactyla, between rhinoceros and equid orthologues, whereas CYP17A1 clustered within the Carnivora. This variability highlights the random adoption of divergent physiological strategies as pregnancy evolved among genetically similar species.

Canid Reproductive Biology: Norm and Unique Aspects in Strategies and Mechanisms

The reproductive physiology of canids is unique compared to other mammalian species. Specifically, the reproductive cycle of female canids is characterized by extended periods of proestrus and estrus followed by obligatory diestrus and protracted ovarian inactivity (anestrus). Although canid reproduction follows this general pattern, studies have shown variations in reproductive biology among species and geographic regions. Understanding of these differences is critical to the development of assisted reproductive technologies including estrus induction, gamete rescue, and embryo production techniques for canid conservation efforts. This review summarizes current knowledge of canid reproduction, including estrus cyclicity, seasonality, and seminal traits, with the emphasis on species diversity. The application of reproductive technologies in wild canid conservation will also be discussed.

Novel Proteomic Profiling of Epididymal Extracellular Vesicles in the Domestic Cat Reveals Proteins Related to Sequential Sperm Maturation with Differences Observed between Normospermic and Teratospermic Individuals

Extracellular vesicles (EVs) secreted by the epididymal epithelium transfer to spermatozoa key proteins that are essential in promoting motility and subsequent fertilization success. Using the domestic cat model, the objectives were to (1) characterize and compare protein content of EVs between segments of the epididymis, and (2) compare EV protein compositions between normo- and teratospermic individuals (producing >60% of abnormal spermatozoa). Epididymal EVs from adult cats were isolated and assessed via liquid chromatography tandem MS. Both male types shared 3008 proteins in total, with 98 and 20 EV proteins unique to normospermic and teratospermic males, respectively. Expression levels of several proteins changed between epididymal segments in both male types. Several proteins in both groups were related to sperm motility (e.g. hexokinase 1, adenylate kinase isoenzyme) and zona pellucida or oolemma binding (e.g. disintegrin and metalloproteinase domain proteins, zona binding proteins 1 and 2). Interestingly, seven cauda-derived EV proteins trended downward in teratospermic compared with normospermic males, which may relate to poor sperm quality. Collective results revealed, for the first time, EV proteins related to sequential sperm maturation with differences observed between normospermic and teratospermic individuals.

Cryopreservation of ferret (Mustela putorius furo) sperm collected by rectal massage and electroejaculation: Comparison of a decelerating and an accelerating freezing rate protocol

The domestic ferret (Mustela putorius furo) provides a good model for developing new reproductive technologies for use with threatened related species. Such technologies could also be used in the reproductive management of this pet species. The present work reports an improved freezing protocol for ferret sperm. Semen was collected by electroejaculation plus rectal massage (in an attempt to reduce the electrical stimulation necessary) from five adult male ferrets, and then subjected to one of two freezing protocols: (a) from 5 to −35°C at 40°C/min, then from −35 to −65°C at 17°C/min, and finally from −65 to −85°C at 3°C/min—a decelerating freezing rate; and (b) from 5 to − 10°C at 5°C/min, and then from −10 to −130°C at 60°C/min—an accelerating freezing rate. After thawing, the viability and acrosomal integrity of the sperm frozen via the two‐step accelerating method were better than those frozen via the three‐step decelerating method (43.3 ± 3.5% and 71.2 ± 3.4% compared with 29.7 ± 3.7% and 58.8 ± 3.4% respectively; p < .05). No differences were seen between the methods with respect to sperm motility variables; most sperm (>90%) remained static with both freezing methods. In conclusion, although the method with accelerating freezing rate was associated with better post‐thaw sperm viability and acrosome integrity values, neither of the two freezing methods tested provided adequate motility results after thawing. Combining rectal massage with electrical stimuli seemed to reduce the number of the latter required for successful sperm collection.

Breakthroughs and new horizons in reproductive biology of rare and endangered animal species

Because of higher extinction rates due to human and natural factors, more basic and applied research in reproductive biology is required to preserve wild species and design proper strategies leading to sustainable populations. The objective of the review is to highlight recent, inspiring breakthroughs in wildlife reproduction science that will set directions for future research and lead to more successes in conservation biology. Despite new tools and approaches allowing a better and faster understanding of key mechanisms, we still know little about reproduction in endangered species. Recently, the most striking advances have been obtained in nonmammalian species (fish, birds, amphibians, or corals) with the development of alternative solutions to preserve fertility or new information about parental nutritional influence on embryo development. A novel way has also been explored to consider the impact of environmental changes on reproduction-the allostatic load-in a vast array of species (from primates to fish). On the horizon, genomic tools are expected to considerably change the way we study wildlife reproduction and develop a concept of "precision conservation breeding." When basic studies in organismal physiology are conducted in parallel, new approaches using stem cells to create artificial gametes and gonads, innovations in germplasm storage, and more research on reproductive microbiomes will help to make a difference. Lastly, multiple challenges (for instance, poor integration of new tools in conservation programs, limited access to study animals, or few publication options) will have to be addressed if we want reproductive biology to positively impact conservation of biodiversity.

Somatic feather follicle cell culture of the gallus domesticus species for creating a wild bird genetic resource bank

The creation of a genetic resource bank of avian species aims to prevent the decline and fragmentation of wild bird populations, which in turn lead to the loss of genetic diversity and, in more serious cases, the extinction of the most threatened species. In order for the collected genetic material to be stored in a bank and useful when necessary, it is essential to improve the technique ensuring its effectiveness. Thus, our study used feather follicle cells from the domestic gallus species to standardize the technique of cell culture and subsequent cryopreservation. This study aimed to establish a protocol, in vitro, of isolation and primary culture of somatic cells derived from the feather follicle, with the purpose of establishing a cell lineage, and evaluate its viability for the biobank formation. Developing feathers of gallus domesticus were collected at 12, 21 and 34 days of age. The feathers were morphologically analyzed and then we selected the region of the calamus due to the presence of pulp for cell culture and cryopreservation. The results showed that it is possible to find cells with distinct morphology; cells in elliptical shape with central nucleus also in elliptical shape, cells with shape and round nucleus, cells compatible with the fibers of the barbules, cell agglomerates and cells adhered to the bottom of the plate with fibroblastatoid shape. After 24 hours of culture there was the presence of primary culture with 80% of confluence and after cryopreservation the average viability after freezing was 68.8%, with cellular morphologies being maintained. Therefore, we proved the isolation of somatic cells from the follicle of bird's feathers, suggesting that this is a source of great value, viable and effective for obtaining biological material for the elaboration of a biobank.

Sex steroids and glucocorticoid ratios in Iberian lynx hair

Knowledge on species' reproductive biology is a fundamental pre-requisite of every conservation effort, but is often lacking. Sex steroids can provide valuable information for the assessment of reproductive success, whereas glucocorticoids are used to assess adrenocortical activity and stress-related bodily adaption. However, due to their perilous condition, access to animals is often difficult, which makes hormone measurement in non-invasively collected hair samples an attractive option. We determined cortisol, cortisone, corticosterone, testosterone and progesterone in Iberian lynx hair using enzyme immunoassay (EIA). Cross-validation was performed with high-performance liquid chromatography (HPLC) and high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). Finally, we statistically evaluated the variations of sex steroids and glucocorticoids according to age, sex, origin, behavior and management. All steroids except corticosterone were detectable in Iberian lynx hair. Hair progesterone measured by EIA was overestimated by cross-reaction with 5α-dihydroprogesterone, a biologically active gestagene, and was highly correlated with HPLC-MS/MS results. Progesterone was higher in adult females compared to all other age-sex groups. Cortisol measured by EIA was overestimated due to antibody cross-reactivity with cortisone and was correlated to the sum of HPLC-MS/MS measurements for cortisol and cortisone. Cortisol was higher in females than in males measured by HPLC-MS/MS, but the EIA results were confounded by the lack of specificity. When using cortisol-cortisone and cortisol-dihydroepiandrosterone ratios, differences were noted between wild-caught and captive-bred lynxes. Additionally, longitudinal EIA measurements of an Iberian lynx after a wildfire showed an inversion of the cortisol-cortisone ratio that later subsided. These results validate the use of hair progesterone measurement for Iberian lynx reproductive monitoring and add to the growing evidence supporting the need for a more comprehensive approach to hair steroid measurement that accounts for local interconversion and co-regulation mechanisms.

Assisted reproductive technologies for endangered species conservation: developing sophisticated protocols with limited access to animals with unique reproductive mechanisms

Assisted reproductive technologies (ARTs) have been proposed as a means of overcoming the significant challenges of managing small, isolated populations of endangered species in zoos. However, efficient protocols for ARTs do not exist for most endangered species. This review will focus on research efforts to characterize unique reproductive mechanisms and develop species-specific ARTs. Central to these studies are assays to measure steroid metabolites in urine or feces and/or training programs to allow unrestrained blood collections and ultrasound evaluations. The resulting information about estrous cycle dynamics, combined with studies of semen collection and processing, provides the foundation for the development of artificial insemination (AI). In vitro fertilization and embryo transfer are also discussed in relation to the advantages these techniques could provide relative to AI, as well as the significant challenges involved with technologies that require oocytes and embryos. Finally, an argument is made for additional research of nontraditional model species (e.g., domestic cats and dogs) and the development of novel models representing unique taxa. Whether these species are studied by zoo-based researchers with the expressed intent of developing ARTs for conservation or academic scientists interested in basic biology, the resulting information will provide a unique, evolutionary perspective on reproduction that could have wide-reaching benefits. The more information we have available, the better our chances will be of developing effective ARTs and making a difference in conservation efforts for endangered species.

Direct role of the C-C motif chemokine receptor 2/monocyte chemoattractant protein 1 system in the feline cumulus oocyte complex†

Studies were designed to (a) evaluate the mRNA expression of the C-C motif chemokine receptor 2 (CCR2) and its chemokine ligands, as well as genes related to periovulatory events, within the cumulus oocyte complex (COC) and follicle wall after a luteinizing hormone (LH) stimulus in cultured feline antral follicles; (b) assess the immunolocalization of CCR2 and its main ligand (monocyte chemoattractant protein 1, MCP1) within the feline COC; and (c) examine the direct effects of exogenous recombinant MCP1 on mRNA expression of the CCR2 receptor and MCP1 as well as key periovulatory genes in the COC, using a feline COC culture system. Both culture systems were developed by our laboratory and exhibit physiological response to gonadotropin stimuli. In summary, this study demonstrated mRNA expression of CCR2 receptor and its assessed ligands (MCP1, MCP2, MCP3, and MCP4) within the feline COC and follicle antral wall, and a significant increase in CCR2 mRNA by LH within the COC. Also, CCR2 and MCP1 immunoreactivity was observed in the oocyte and cumulus cells of the feline COC. Remarkably, this is the first report, in any species, describing a direct effect of the recombinant MCP1 in the CCR2/MCP1 system within the COC, by increasing the mRNA levels of key genes involved in the ovulatory cascade, as well as its own receptor CCR2. Together, these data suggest that CCR2 receptor signaling in the COC may regulate events critical for promoting cumulus oocyte expansion and/or oocyte maturation.

Integrating fertility preservation and cryo-banking into the conservation of rare and endangered deer species

More than 50 deer species live in diverse ecosystems around the world. Unfortunately, most of them are threatened or endangered because of over-hunting, poaching or habitat destruction. Protection of wild populations (in situ) and management of animal collections in zoos and breeding centres (ex situ) are complementary conservation efforts relying on multidisciplinary approaches. Reproductive biology of deer species is one of the critical areas that still needs to be thoroughly studied to ensure the success of in situ or ex situ programs. Interestingly, there is a vast diversity in reproductive traits within the deer family (from anatomy to breeding-season patterns). On the basis of this fundamental knowledge, adapted reproductive biotechnologies have been developed to enhance reproduction and preserve fertility of individuals. Early works on artificial insemination (AI), in vitro fertilisation (IVF), and germplasm freezing in the more common red deer, sika deer and white-tailed deer have been highly inspiring to projects aiming at saving endangered deer species. A few fawn births following AI or IVF using frozen semen have been reported in wild species (e.g. Eld’s deer, Rucervus eldii thamin); however, assisted reproductive techniques and cryo-banking are currently not integrated into the management of rare and endangered populations. Knowing that many deer populations are rapidly declining in situ and ex situ, there is now an urgent need for better strategies and more fertility preservation options. The objectives of the present article are to review (1) existing reproductive biotechnologies to preserve fertility of different deer species and (2) how to integrate these approaches into the management of rare and endangered populations to address conservation issues.

Breeding Centers, Private Ranches, and Genomics for Creating Sustainable Wildlife Populations

Human-induced changes to environments are causing species declines. Beyond preserving habitat (in situ), insurance (ex situ) populations are essential to prevent species extinctions. The Conservation Centers for Species Survival (C2S2) is leveraging space of breeding centers and private ranches to produce “source populations”—genetically diverse reservoirs that also support research and reintroductions. The initial focus is on four African antelopes. C2S2 has developed a program, the Source Population Alliance, that emphasizes animals living in spacious, naturalistic conditions in greater numbers than can be accommodated by urban zoos. Simulation modeling demonstrates how herds can rapidly increase population abundance and retain genetic diversity. Advances in genomics and resulting DNA data allow monitoring of genetic diversity and parentage as well as refined decision-making. This approach, neither pure in situ nor ex situ, but rather “sorta situ”, is an innovative way of linking public and private sector resources to ensure that endangered species survive.

Oviductal extracellular vesicles interact with the spermatozoon's head and mid-piece and improves its motility and fertilizing ability in the domestic cat

Fertilization and early embryo development are regulated by a unique maternal-gamete/embryo cross-talk within the oviduct. Recent studies have shown that extracellular vesicles (EVs) within the oviduct play important roles in mediating this developmental process. Here, we examined the influence of oviductal EVs on sperm function in the domestic cat. We demonstrated that (1) EVs are enriched in proteins related to energy metabolism, membrane modification, and reproductive function; (2) EVs bound and fused with the membranes of the acrosome and mid piece; and (3) incubating sperm with EVs improved motility, fertilizing capacity of cat spermatozoa and prevented acrosomal exocytosis in vitro. These findings indicated that oviductal EVs mediate sperm function and fertilization in the cat and provides new insights to improve sperm cryopreservation and in vitro fertilization in the domestic and wild felids and human.

Vitrification of canine ovarian tissues with polyvinylpyrrolidone preserves the survival and developmental capacity of primordial follicles

Ovarian tissue cryopreservation combined with immature follicle development can preserve female fertility in wildlife, regardless of age or reproductive timing. To investigate the effects of different cryopreservation methods and cryoprotectants on follicular survival and developmental capacity, ovarian cortical pieces from 15 dogs were cryopreserved by slow freezing or vitrification with different additional cryoprotectants as follows: dimethyl sulfoxide (DMSO), polyvinylpyrrolidone (PVP), combined DMSO and PVP (each at half the concentration of when used independently), or none (control). Cryopreserved ovarian tissues were evaluated by neutral red staining, histology, and xenotransplantation assays. Among cryopreservation conditions tested, vitrification with combined DMSO and PVP significantly improved the maintenance of follicular morphology compared to that in control. Furthermore, ovarian tissues vitrified using this condition maintained follicle morphology and developmental capacity 9 weeks after grafting, as shown by an increased percentage of primary and secondary follicles and a significant decrease in the transition stage from primordial to primary stage follicles 5 and 9 weeks after grafting. In contrast, slow freezing and control groups lost intact follicles by 5 weeks after grafting. The described cryopreservation techniques, which preserve canine follicle development, will build the foundation of ovarian tissue cryopreservation to preserve female fertility in wild canids.

Molecular effects of copper on the reproductive system of mytilus galloprovincialis

This study aims to assess the effects induced by 24 hr exposure to a subtoxic copper concentration on the reproductive system (gonads, spermatozoa, and protamine-like [PL] proteins) of Mytilus galloprovincialis. Inductively coupled plasma-mass spectrometry indicated accumulation of this metal in gonads, spermatozoa, and PL proteins of exposed mussels. Further, real-time polymerase chain reaction analyses showed altered expression levels of mt10 and PL proteins genes in spermatozoa and gonads, respectively, of exposed mussels. Protamine-like proteins, which represent the main basic component of sperm chromatin of this organism, showed a higher DNA binding affinity and a different DNA binding mode in exposed mussels. Moreover, an increased amount of NaCl was required for the release from sperm nuclei of PL-III, the main PL protein component. Finally, PL proteins extracted from exposed mussels promoted DNA oxidative damage in the presence of H ₂ O _2. These results demonstrate that the tolerable copper amount could also affect the properties of PL proteins and determine the negative effects on the reproductive system of this organism. These analyses could be useful to develop quick and efficient chromatin-based genotoxicity tests for pollution biomonitoring programs.

Semen Cryopreservation and Banking for the Conservation of Neotropical Carnivores

Neotropical carnivores include a large number of threatened and endangered species. It is critical to develop conservation efforts to ensure the sustainability of populations in situ and ex situ. The highest priorities are to protect natural habitats and better understand the biology of rare species. Conservation efforts also are directed toward the implementation of breeding programs and the development of reproductive biotechnologies in which the cryopreservation of male gametes plays a major role. It also is fundamental to create semen banks that contribute to maintaining genetic diversity in small and endangered populations. The present article aims at reviewing the state of the art in cryopreservation of semen from neotropical carnivores and discuss the development of systematic banking for the conservation of these understudied species.

Preservation of female fertility in humans and animal species

A detailed understanding of the cryobiology of gametes and complex tissues has led to the development of methods that facilitate the successful low temperature banking of isolated mature human oocytes, or immature oocytes in situ within fragments of human ovarian cortex. Although many outstanding research challenges remain to be addressed, the successful development of new treatments to preserve female fertility for a range of clinical indications has largely been underpinned by the conduct of extensive, fundamental research on oocytes and ovarian tissues from a number of laboratory and commercially important farm species. Indeed, the most recent evidence from large animals suggests that it is also possible to cryopreserve intact whole ovaries along with their supporting vasculature for later auto-transplantation and restoration of natural fertility. This review will explore how the methods developed to preserve human oocytes and ovarian tissues can now be used strategically to support the development of conservation strategies aimed at safeguarding the genetic diversity of commercially important domestic animals and also of preserving the female germplasm for wild animals and endangered species.

Stromal-derived factor 1 directly promotes genes expressed within the ovulatory cascade in feline cumulus oocyte complexes

PURPOSE

We hypothesized that the chemokine SDF1/CXCR4 system was present in feline cumulus-oocyte complexes (COCs) and that COCs cultured with SDF1 would directly upregulate gene expression in the ovulatory cascade.

METHODS

Ovaries (n = 50) were obtained from adult domestic cats during the breeding season and COCs were recovered from antral follicles. Because IVM media triggers cumulus-oocyte expansion, culture conditions needed to be optimized to study periovulatory genes. After optimization, the effects of 25 ng/ml SDF1 and the CXCR4 inhibitor were examined in a COC culture for 3, 12, and 24 h.

RESULTS

MEM-hepes with 1% of charcoal stripped-FBS was the optimized culture medium, assessed by the expansion of COCs at 24 h in the gonadotropin (GNT) group but not in the media with serum alone. The mRNA expression of HAS2, TNFAIP6, PTX3, and AREG peaked at 3 h in GNT group as compared to all other groups (p < 0.05). COCs cultured with SDF1 showed increased HAS2 and TNFAIP6 mRNA expression at 3 h compared to negative controls and to the CXCR4 inhibitor group. CXCR4 and SDF1 immunostaining was present in both cumulus cells and the oocyte.

CONCLUSIONS

These results demonstrate that GNT stimulation upregulates key periovulatory genes and expansion in feline COCs from antral follicles, and support the use of this culture system to examine molecular processes within the COC. In addition, SDF1 directly promotes key periovulatory genes in feline COCs, suggesting that the SDF1-CXCR4 pathway may extend its function beyond a chemoattractant, and may play a direct role within the COC.

The mutual benefits of research in wild animal species and human-assisted reproduction

Studying the reproductive biology of wild animal species produces knowledge beneficial to their management and conservation. However, wild species also share intriguing similarities in reproductive biology with humans, thereby offering alternative models for better understanding the etiology of infertility and developing innovative treatments. The purpose of this review is to raise awareness in different scientific communities about intriguing connections between wild animals and humans regarding infertility syndromes or improvement of fertility preservation. The objectives are to (1) highlight commonalities between wild species and human fertility, (2) demonstrate that research in wild species-assisted reproductive technologies can greatly enhance success in human reproductive medicine, and (3) recognize that human fertility preservation is highly inspiring and relevant to wild species conservation. In addition to having similar biological traits in some wild species and humans, the fact of sharing the same natural environment and the common needs for more options in fertility preservation are strong incentives to build more bridges that will eventually benefit both animal conservation and human reproductive medicine.

Pairing ultrasonography with endocrinology to elucidate underlying mechanisms of successful pregnancy in the northern fur seal (Callorhinus ursinus)

Reproductive success is one of the central tenets of conservation management programs, yet the inability to study underlying physiological processes in a minimally-invasive manner and the unpredictable nature of wild animal populations leaves large gaps in our knowledge of factors critical to successful reproduction in wild species. This study integrated ultrasonography of the reproductive tract and analysis of reproductive hormones in 172 northern fur seals (Callorhinus ursinus) to identify intrinsic factors associated with reinitiating embryonic growth at the end of diapause. Within the first 3-4 weeks of active gestation, pregnant fur seals (n = 126) had a larger corpus luteum and fewer antral follicles than non-pregnant fur seals, or those still in diapause (n = 46). This suggests that the conceptus drives changes in ovarian status to convey its presence to the female. Morphological changes in the reproductive tract associated with pregnancy were not reflected in differences in endocrine profiles (estradiol, estrone, progesterone, and relaxin) between pregnant and non-pregnant individuals. Hormone concentrations correlated more strongly with calendar date than with the presence or size of the conceptus, demonstrating that none of these reproductive hormones were reliable markers for early pregnancy diagnosis. Instead, the northern fur seal's long diestrus may serve to reduce the probability of a temporal mismatch between corpus luteum regression and embryo implantation. Indeed, conception rates were high and confirmed rates of pregnancy loss were relatively low (11%). In this study, minimally-invasive ultrasonography was used in wild pinnipeds to detect very early pregnancy (embryonic vesicles >2 mm) in combination with ovarian and endocrine dynamics at the time of embryo implantation, shedding light on mechanisms for maternal recognition of pregnancy. This study is also the first to track whether these same animals carried the embryo to term, by observing fur seals during the birthing season the following year. Data do not support the notion that decreased pregnancy rates or higher pregnancy loss rates are major contributing factors to the northern fur seal's population decline.

The preservation of vital functions in cat ovarian tissues during vitrification depends more on the temperature of the cryoprotectant exposure than on the sucrose supplementation

The objective of this study was to better characterize the impact of cryoprotectant exposure (temperature and sucrose supplementation) on the health and function of preantral follicles in ovarian tissues during vitrification using the domestic cat model. Ovarian cortical pieces from peri-pubertal individuals were exposed to cryoprotectants at 4 °C or room temperature and supplemented with 0 or 0.5 M of sucrose, followed by vitrification. After rapid warming, cortical pieces were cultured in vitro and assessed for normal follicular morphology, viability and resumption of transcriptional activities for up to 7 days. Throughout the culture period, follicular morphology (up to 67.5% normal follicles) and global RNA transcription (up to 50.9% follicles with transcriptional activity) in warmed tissues were improved by cryoprotectant exposure at 4 °C compared to room temperature, but viability (up to 84.6% viable follicles) did not seem to be affected by exposure temperature. Sucrose supplementation did not have a consistent effect as it increased RNA transcription but decreased normal follicular morphology. For the first time, the study demonstrated that the preservation of critical tissue functions, such as the transcriptional activities, highly depends on the temperature of the cryoprotectant exposure and not necessarily on the presence of sucrose.

Cryopreservation and other assisted reproductive technologies for the conservation of threatened amphibians and reptiles: bringing the ARTs up to speed

Amphibians and reptiles are experiencing serious declines, with the number of threatened species and extinctions growing rapidly as the modern biodiversity crisis unfolds. For amphibians, the panzootic of chytridiomycosis is a major driver. For reptiles, habitat loss and harvesting from the wild are key threats. Cryopreservation and other assisted reproductive technologies (ARTs) could play a role in slowing the loss of amphibian and reptile biodiversity and managing threatened populations through genome storage and the production of live animals from stored material. These vertebrate classes are at different stages of development in cryopreservation and other ARTs, and each class faces different technical challenges arising from the separate evolutionary end-points of their reproductive biology. For amphibians, the generation of live offspring from cryopreserved spermatozoa has been achieved, but the cryopreservation of oocytes and embryos remains elusive. With reptiles, spermatozoa have been cryopreserved in a few species, but no offspring from cryopreserved spermatozoa have been reported, and the generation of live young from AI has only occurred in a small number of species. Cryopreservation and ARTs are more developed and advanced for amphibians than reptiles. Future work on both groups needs to concentrate on achieving proof of concept examples that demonstrate the use of genome storage and ARTs in successfully recovering threatened species to increase awareness and support for this approach to conservation.

Biobanking efforts and new advances in male fertility preservation for rare and endangered species

Understanding and sustaining biodiversity is a multi-disciplinary science that benefits highly from the creation of organized and accessible collections of biomaterials (Genome Resource Banks). Large cryo-collections are invaluable tools for understanding, cataloging, and protecting the genetic diversity of the world's unique animals and plants. Specifically, the systematic collection and preservation of semen from rare species has been developed significantly in recent decades with some biobanks now being actively used for endangered species management and propagation (including the introduction of species such as the black-footed ferret and the giant panda). Innovations emerging from the growing field of male fertility preservation for humans, livestock species, and laboratory animals are also becoming relevant to the protection and the propagation of valuable domestic and wild species. These new approaches extend beyond the “classical” methods associated with sperm freezing to include testicular tissue preservation combined with xenografting or in vitro culture, all of which have potential for rescuing vast amounts of unused germplasm. There also are other options under development that are predicted to have a high impact within the next decade (stem cell technologies, bio-stabilization of sperm cells at ambient temperatures, and the use of genomics tools). However, biobanking efforts and new fertility preservation strategies have to expand the way beyond mammalian species, which will offer knowledge and tools to better manage species that serve as valuable biomedical models or require assistance to reverse endangerment.

Beyond the mouse monopoly: studying the male germ line in domestic animal models

Spermatogonial stem cells (SSCs) are the foundation of spermatogenesis and essential to maintain the continuous production of spermatozoa after the onset of puberty in the male. The study of the male germ line is important for understanding the process of spermatogenesis, unravelling mechanisms of stemness maintenance, cell differentiation, and cell-to-cell interactions. The transplantation of SSCs can contribute to the preservation of the genome of valuable individuals in assisted reproduction programs. In addition to the importance of SSCs for male fertility, their study has recently stimulated interest in the generation of genetically modified animals because manipulations of the male germ line at the SSC stage will be maintained in the long term and transmitted to the offspring. Studies performed mainly in the mouse model have laid the groundwork for facilitating advancements in the field of male germ line biology, but more progress is needed in nonrodent species in order to translate the technology to the agricultural and biomedical fields. The lack of reliable markers for isolating germ cells from testicular somatic cells and the lack of knowledge of the requirements for germ cell maintenance have precluded their long-term maintenance in domestic animals. Nevertheless, some progress has been made. In this review, we will focus on the state of the art in the isolation, characterization, culture, and manipulation of SSCs and the use of germ cell transplantation in domestic animals.

Cryobiology: principles, species conservation and benefits for coral reefs

Coral reefs are some of the oldest, most diverse and valuable ecosystems on Earth because they can support one-quarter of all marine life in our oceans. Despite their importance, the world’s coral reefs continue to be degraded at unprecedented rates by local and global threats that are warming and creating a more acidic ocean. This paper explores the reproductive challenges of coral for ex situ conservation, using IVF and cryopreservation, and our practical biobanking methods. Coral present challenges for cryopreservation because their reproductive period is often limited to a few nights yearly, they are mostly hermaphrodites with diverse modes of reproduction, including asexual reproduction (i.e. fragmentation and parthenogenesis) and sexual reproduction (i.e. self- and cross-fertilisation) and they express physiological toxins that can inhibit cryopreservation. We have banked spermatozoa from 12 coral species using the same field-hardy methods and have created new coral with thawed spermatozoa. In addition, we describe the cryopreservation of coral symbionts, whose physiology only permits the highest success seasonally. As part of a multidisciplinary conservation strategy, these collections may provide a major hedge against extinction for corals facing the damaging effects of climate change and loss of genetic diversity, and promise to help offset threats to our reefs worldwide.

Progestin priming before gonadotrophin stimulation and AI improves embryo development and normalises luteal function in the cat

Exogenous gonadotrophins administered before AI can adversely alter endocrine dynamics and inhibit embryo development in felids. In the present study, we tested the hypothesis that priming the domestic cat ovary with progestin mitigates the negative influence of gonadotrophin therapy by normalising early embryogenesis and luteal function. Queens were given either: (1) progestin pretreatment plus chorionic gonadotrophins (n=8; primed); or (2) gonadotrophins only (n=8; unprimed). Ovulatory response was assessed laparoscopically, and cats with fresh corpora lutea (CL) were inseminated in utero. Ovariohysterectomy was performed 3 days later to recover intra-oviductal embryos for in vitro culture; one ovary was prepared for histology, and CL from the remaining ovary were excised and assessed for progesterone content and targeted gene expression. Of the six primed and seven unprimed queens inseminated, embryo(s) were recovered from five individuals per group. Embryos from progestin-primed donors more closely simulated normal stage in vivo development (P<0.05). No 2- or 4-cell embryos from either group developed beyond 16-cells in vitro; however, 50% of unprimed and 66.7% of primed (P>0.05) 5-16-cell embryos progressed to morulae or blastocysts by Day 4 of culture. Although histological characteristics were unaffected by progestin priming (P>0.05), luteal progesterone was unusually high (P<0.05) in unprimed compared with primed cats (72.4±5.8 vs. 52.2±5.5 ng mg(-1), respectively). Two genes associated with progesterone biosynthesis (luteinising hormone receptor and 3β-hydroxysteroid dehydrogenase) were upregulated in unprimed versus primed individuals (P=0.05 and P<0.05, respectively), indicating potential mechanistic pathways for the protective influence of pre-emptive progestin treatment. Building on earlier findings that progestin priming prevents spontaneous ovulation, increases ovarian sensitivity to gonadotrophins and ensures a normative endocrine environment, the present study demonstrates that pretreatment with this steroid also benefits embryo development and normalisation of early luteal function.

Felis catus ovary as a model to study follicle biology in vitro

PURPOSE

The current study was designed to evaluate the response of individual intact antral follicles from adult female domestic cats to a luteinizing hormone (LH) stimulus in vitro by assessing cumulus-oocyte expansion (C-OE) and steroid production.

METHODS

C-OE and steroid levels (estradiol [E2] and progesterone [P4]) obtained from individual antral feline follicles (n = 366 follicles; n = 56 cats) were analyzed after 12 or 24 h of culture in the presence or absence of LH (low [3.4 ng/ml] or high [100 ng/ml]).

RESULTS

At the end of the culture, the highest percentage of expanded cumulus-oocyte complexes (COCs) was observed in the LH groups at 12 or 24 h in comparison to their controls (p < 0.001). There was a significant increase in expanded COCs when comparing LH concentrations (high vs. low) at 12 or 24 h. Higher levels of both E2 and P4 were observed in the media from antral follicles after 12 and 24 h of culture in the presence of LH (both concentration, p < 0.05). There was no association between hormone levels and follicle diameter; high variability was observed in the steroid levels produced by antral follicles within all treatment groups.

CONCLUSIONS

These data indicate, for the first time, that feline antral follicles (0.5-2 mm) from different stages of the natural estrous cycle can be cultured and will respond to an LH stimulus, based on an increase in steroid levels as well as C-OE after 12 or 24 h in culture.