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Arregui L, Koch JC, Tiersch TR. Transitioning from a research protocol to a scalable applied pathway for Xenopus laevis sperm cryopreservation at a national stock center: The effect of cryoprotectants. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2024; 342:291-300. [PMID: 37984495 PMCID: PMC11094805 DOI: 10.1002/jez.b.23228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 10/17/2023] [Accepted: 10/27/2023] [Indexed: 11/22/2023]
Abstract
Sperm cryopreservation is a critical tool for safeguarding and managing valuable genetic resources. Protocols for cryopreservation of Xenopus laevis sperm were available but lacking sperm quality evaluation and scalability and the outcomes were inconsistent. The goal of this study was to begin developing a center-level cryopreservation pathway for this species by integrating French straws as containers that would facilitate germplasm repository development. The objectives were to analyze the effect of: (1) three sperm concentrations (33, 50, and 100 × 106 sperm/mL) on post-thaw fertilization, (2) three final concentrations (2.5%, 5%, and 10%) of dimethyl sulfoxide, methanol, and dimethylformamide (DMFA) on sperm membrane integrity of fresh and frozen samples, (3) two concentrations (5% and 10%) of DMFA with and without 5% sucrose at four cooling rates (5, 10, 20, and 40°C/min) on sperm membrane integrity and motility, and (4) egg exposure to different concentrations of DMFA on fertilization. Few differences in sperm viability were found among fresh samples incubated in cryoprotectants, but thawed samples frozen in methanol or DMFA presented higher membrane integrity. Samples frozen in 10% DMFA at 20°C/min showed higher membrane integrity (60 ± 7%) than other DMFA concentrations and cooling rates, and the same total motility (30 ± 7%) as at 10°C/min. Higher DMFA concentrations (10%-13%) were detrimental for embryo development compared to lower concentrations (<6%). This study provided a reliable protocol for sperm cryopreservation in Xenopus laevis to yield an application pathway with potential for high throughput that can be used as a roadmap for work with other species.
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Affiliation(s)
- Lucía Arregui
- School of Renewable Natural Resources, Aquatic Germplasm and Genetic Resources Center, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
| | - Jack C Koch
- School of Renewable Natural Resources, Aquatic Germplasm and Genetic Resources Center, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
| | - Terrence R Tiersch
- School of Renewable Natural Resources, Aquatic Germplasm and Genetic Resources Center, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
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Anastas ZM, Byrne PG, O'Brien JK, Hobbs RJ, Upton R, Silla AJ. The Increasing Role of Short-Term Sperm Storage and Cryopreservation in Conserving Threatened Amphibian Species. Animals (Basel) 2023; 13:2094. [PMID: 37443891 DOI: 10.3390/ani13132094] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/15/2023] [Accepted: 06/19/2023] [Indexed: 07/15/2023] Open
Abstract
Multidisciplinary approaches to conserve threatened species are required to curb biodiversity loss. Globally, amphibians are facing the most severe declines of any vertebrate class. In response, conservation breeding programs have been established in a growing number of amphibian species as a safeguard against further extinction. One of the main challenges to the long-term success of conservation breeding programs is the maintenance of genetic diversity, which, if lost, poses threats to the viability and adaptive potential of at-risk populations. Integrating reproductive technologies into conservation breeding programs can greatly assist genetic management and facilitate genetic exchange between captive and wild populations, as well as reinvigorate genetic diversity from expired genotypes. The generation of offspring produced via assisted fertilisation using frozen-thawed sperm has been achieved in a small but growing number of amphibian species and is poised to be a valuable tool for the genetic management of many more threatened species globally. This review discusses the role of sperm storage in amphibian conservation, presents the state of current technologies for the short-term cold storage and cryopreservation of amphibian sperm, and discusses the generation of cryo-derived offspring.
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Affiliation(s)
- Zara M Anastas
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Phillip G Byrne
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Justine K O'Brien
- Taronga Institute of Science and Learning, Taronga Conservation Society Australia, Mosman, NSW 2088, Australia
| | - Rebecca J Hobbs
- Taronga Institute of Science and Learning, Taronga Conservation Society Australia, Mosman, NSW 2088, Australia
| | - Rose Upton
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Aimee J Silla
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
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Arregui L, Martinez-Pastor F, Arroyo F, Gosálvez J. Determining the effects of sperm activation in anuran cloaca on motility and DNA integrity in Epidalea calamita (Bufonidae). Reprod Fertil Dev 2021; 34:438-446. [PMID: 34399881 DOI: 10.1071/rd21063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 06/24/2021] [Indexed: 11/23/2022] Open
Abstract
The effect of time inside the animal's cloaca on sperm quality after hormone-induced spermiation is unknown. However, this knowledge is critical for the development of assisted reproductive biotechnologies in amphibians. Out-of-season spermatozoa were collected from Epidalea calamita for 4h after injection of 10IU g-1 human chorionic gonadotrophin either hourly (Group I (n=10); four samples per male) or every 2h (Group II (n=9); two samples per male). Sperm samples were assessed for motility and DNA integrity using the sperm chromatin dispersion (SCD) test and the sperm chromatin structure assay (SCSA). The collection strategy affected total motility (mean (±s.e.m.) 84.4±9.9% vs 73.6±16.7% in Group I and II respectively; P=0.014) and the sperm motility index (67.6±17.7% vs 57.6±16.3% in Group I and II respectively; P=0.034). There was a significant effect of the male in Group II, but not in Group I. In Group I, the quality of the first samples collected was lower than that of samples collected thereafter (P ≤ 0.032). No significant correlations were found between the results of the SCD test and SCSA, showing that these techniques provide different information in this species. In conclusion, collecting spermatozoa every hour resulted in better sperm quality and may be more efficient. However, the between-male differences were considerable and collection of spermatozoa at just 1h after hormone treatment produced lower-quality spermatozoa.
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Affiliation(s)
- Lucía Arregui
- Department of Biology, Universidad Autónoma de Madrid, C/Darwin 2, Madrid 28049, Spain; and Corresponding author
| | - Felipe Martinez-Pastor
- Institute of Animal Health and Cattle Development (INDEGSAL), Universidad de León, Campus de Vegazana s/n, León 24071, Spain; and Department of Molecular Biology (Cell Biology), Universidad de León, Campus de Vegazana s/n, León 24071, Spain
| | - Francisca Arroyo
- Department of Biology, Universidad Autónoma de Madrid, C/Darwin 2, Madrid 28049, Spain
| | - Jaime Gosálvez
- Department of Biology, Universidad Autónoma de Madrid, C/Darwin 2, Madrid 28049, Spain
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Upton R, Clulow S, Calatayud NE, Colyvas K, Seeto RGY, Wong LAM, Mahony MJ, Clulow J. Generation of reproductively mature offspring from the endangered green and golden bell frog Litoria aurea using cryopreserved spermatozoa. Reprod Fertil Dev 2021; 33:562-572. [PMID: 33820600 DOI: 10.1071/rd20296] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 02/25/2021] [Indexed: 11/23/2022] Open
Abstract
Amphibians are becoming increasingly reliant on captive breeding programs for continued survival. Assisted reproductive technologies including gamete cryopreservation and IVF can help reduce costs of breeding programs, provide insurance against extinction and assist genetic rescue in wild populations. However, the use of these technologies to produce reproductively mature offspring has only been demonstrated in a few non-model species. We aimed to optimise sperm cryopreservation in the threatened frog Litoria aurea and generate mature offspring from frozen-thawed spermatozoa by IVF. We tested three concentrations (1.4, 2.1 and 2.8M) of the cryoprotectants dimethylsulfoxide (DMSO) and glycerol with 0.3M sucrose. Using DMSO was more likely to result in recovery of sperm motility, vitality and acrosome integrity than glycerol, regardless of concentration, with forward progressive motility being most sensitive to damage. The lowest concentrations of 1.4 and 2.1M provided the best protection regardless of cryoprotectant type. Spermatozoa cryopreserved in 2.1M DMSO outperformed spermatozoa cryopreserved in equivalent concentrations of glycerol in terms of their ability to fertilise ova, resulting in higher rates of embryos hatching and several individuals reaching sexual maturity. We have demonstrated that sperm cryopreservation and subsequent offspring generation via IVF is a feasible conservation tool for L. aurea and other threatened amphibians.
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Affiliation(s)
- Rose Upton
- The Conservation Biology Research Group, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia; and FAUNA Research Alliance, PO Box 5092, Kahibah, NSW 2290, Australia; and Corresponding author
| | - Simon Clulow
- FAUNA Research Alliance, PO Box 5092, Kahibah, NSW 2290, Australia; and Centre for Conservation Ecology and Genomics, Institute for Applied Ecology, University of Canberra, Bruce, ACT 2617, Australia
| | - Natalie E Calatayud
- FAUNA Research Alliance, PO Box 5092, Kahibah, NSW 2290, Australia; and Taronga Institute of Science and Learning, Taronga Conservation Society Australia, Taronga Western Plains Zoo, Dubbo, NSW 2830, Australia; and San Diego Zoo Global-Beckman Center for Conservation Research, 15600 San Pasqual Valley Road, Escondido, CA 92027, USA
| | - Kim Colyvas
- School of Mathematical and Physical Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Rebecca G Y Seeto
- The Conservation Biology Research Group, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Lesley A M Wong
- The Conservation Biology Research Group, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Michael J Mahony
- The Conservation Biology Research Group, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia; and FAUNA Research Alliance, PO Box 5092, Kahibah, NSW 2290, Australia
| | - John Clulow
- The Conservation Biology Research Group, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia; and FAUNA Research Alliance, PO Box 5092, Kahibah, NSW 2290, Australia
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Poo S, Hinkson KM. Amphibian conservation using assisted reproductive technologies: Cryopreserved sperm affects offspring morphology, but not behavior, in a toad. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2019.e00809] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Browne RK, Silla AJ, Upton R, Della-Togna G, Marcec-Greaves R, Shishova NV, Uteshev VK, Proaño B, Pérez OD, Mansour N, Kaurova SA, Gakhova EN, Cosson J, Dyzuba B, Kramarova LI, McGinnity D, Gonzalez M, Clulow J, Clulow S. Sperm collection and storage for the sustainable management of amphibian biodiversity. Theriogenology 2020; 133:187-200. [PMID: 31155034 DOI: 10.1016/j.theriogenology.2019.03.035] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 03/30/2019] [Indexed: 02/06/2023]
Abstract
Current rates of biodiversity loss pose an unprecedented challenge to the conservation community, particularly with amphibians and freshwater fish as the most threatened vertebrates. An increasing number of environmental challenges, including habitat loss, pathogens, and global warming, demand a global response toward the sustainable management of ecosystems and their biodiversity. Conservation Breeding Programs (CBPs) are needed for the sustainable management of amphibian species threatened with extinction. CBPs support species survival while increasing public awareness and political influence. Current CBPs only cater for 10% of the almost 500 amphibian species in need. However, the use of sperm storage to increase efficiency and reliability, along with an increased number of CBPs, offer the potential to significantly reduce species loss. The establishment and refinement of techniques over the last two decades, for the collection and storage of amphibian spermatozoa, gives confidence for their use in CBPs and other biotechnical applications. Cryopreserved spermatozoa has produced breeding pairs of frogs and salamanders and the stage is set for Lifecycle Proof of Concept Programs that use cryopreserved sperm in CBPs along with repopulation, supplementation, and translocation programs. The application of cryopreserved sperm in CBPs, is complimentary to but separate from archival gene banking and general cell and tissue storage. However, where appropriate amphibian sperm banking should be integrated into other global biobanking projects, especially those for fish, and those that include the use of cryopreserved material for genomics and other research. Research over a broader range of amphibian species, and more uniformity in experimental methodology, is needed to inform both theory and application. Genomics is revolutionising our understanding of biological processes and increasingly guiding species conservation through the identification of evolutionary significant units as the conservation focus, and through revealing the intimate relationship between evolutionary history and sperm physiology that ultimately affects the amenability of sperm to refrigerated or frozen storage. In the present review we provide a nascent phylogenetic framework for integration with other research lines to further the potential of amphibian sperm banking.
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Affiliation(s)
- Robert K Browne
- Sustainability America, Sarteneja, Corozal District, Belize.
| | - Aimee J Silla
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, NSW, 2522, Australia
| | - Rose Upton
- School of Environmental and Life Sciences, University of Newcastle, Callaghan Drive, Callaghan, NSW, 2308, Australia
| | - Gina Della-Togna
- Smithsonian Tropical Research Institute, Panama Amphibian Rescue and Conservation Project, Panama City, Panama; Universidad Interamericana de Panamá, Dirección de Investigación, Sede Central, Panama
| | - Ruth Marcec-Greaves
- National Amphibian Conservation Center Detroit Zoological Society, Detroit, USA
| | - Natalia V Shishova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Victor K Uteshev
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Belin Proaño
- Escuela de Ciencias Biológicas, Pontificia Universidad Católica Del Ecuador, Ecuador
| | - Oscar D Pérez
- Escuela de Ciencias Biológicas, Pontificia Universidad Católica Del Ecuador, Ecuador
| | - Nabil Mansour
- Faculty of Veterinary Medicine, Kafrelsheikh University, Egypt
| | - Svetlana A Kaurova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Edith N Gakhova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Jacky Cosson
- University of South Bohemia in Ceske Budejovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, 38925, Vodnany, Czech Republic
| | - Borys Dyzuba
- University of South Bohemia in Ceske Budejovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, 38925, Vodnany, Czech Republic
| | - Ludmila I Kramarova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | | | - Manuel Gonzalez
- Departamento de Producción Animal, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico
| | - John Clulow
- School of Environmental and Life Sciences, University of Newcastle, Callaghan Drive, Callaghan, NSW, 2308, Australia
| | - Simon Clulow
- School of Environmental and Life Sciences, University of Newcastle, Callaghan Drive, Callaghan, NSW, 2308, Australia; Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
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Clulow J, Upton R, Trudeau VL, Clulow S. Amphibian Assisted Reproductive Technologies: Moving from Technology to Application. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1200:413-463. [PMID: 31471805 DOI: 10.1007/978-3-030-23633-5_14] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Amphibians have experienced a catastrophic decline since the 1980s driven by disease, habitat loss, and impacts of invasive species and face ongoing threats from climate change. About 40% of extant amphibians are under threat of extinction and about 200 species have disappeared completely. Reproductive technologies and biobanking of cryopreserved materials offer technologies that could increase the efficiency and effectiveness of conservation programs involving management of captive breeding and wild populations through reduced costs, better genetic management and reduced risk of species extinctions. However, there are relatively few examples of applications of these technologies in practice in on-the-ground conservation programs, and no example that we know of where genetic diversity has been restored to a threatened amphibian species in captive breeding or in wild populations using cryopreserved genetic material. This gap in the application of technology to conservation programs needs to be addressed if assisted reproductive technologies (ARTs) and biobanking are to realise their potential in amphibian conservation. We review successful technologies including non-invasive gamete collection, IVF and sperm cryopreservation that work well enough to be applied to many current conservation programs. We consider new advances in technology (vitrification and laser warming) of cryopreservation of aquatic embryos of fish and some marine invertebrates that may help us to overcome factors limiting amphibian oocyte and embryo cryopreservation. Finally, we address two case studies that illustrate the urgent need and the opportunity to implement immediately ARTs, cryopreservation and biobanking to amphibian conservation. These are (1) managing the biosecurity (disease risk) of the frogs of New Guinea which are currently free of chytridiomycosis, but are at high risk (2) the Sehuencas water frog of Bolivia, which until recently had only one known surviving male.
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Affiliation(s)
- J Clulow
- School of Environmental and Life Sciences, University of Newcastle, Newcastle, NSW, Australia.
| | - R Upton
- School of Environmental and Life Sciences, University of Newcastle, Newcastle, NSW, Australia
| | - V L Trudeau
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - S Clulow
- Department of Biological Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW, Australia
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Amphibian Sperm Chromatin Structure and Function and Its Relevance to Sperm Preservation. J HERPETOL 2018. [DOI: 10.1670/17-163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Campbell DEK, Montgomerie RD, Langlois VS. Lifecycle exposure to perchlorate differentially alters morphology, biochemistry, and transcription as well as sperm motility in Silurana tropicalis frogs. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 237:196-204. [PMID: 29482025 DOI: 10.1016/j.envpol.2018.02.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Revised: 01/29/2018] [Accepted: 02/12/2018] [Indexed: 06/08/2023]
Abstract
Perchlorate (ClO4-) contamination has been reported in ground and surface waters across North America. However, few studies have examined the effects of prolonged exposure to this thyroid hormone disrupting chemical, particularly at environmentally relevant concentrations in lower vertebrates, such as amphibians. The aim of this study was to examine the effects of a yearlong chronic exposure to ClO4- in adult male and female Western clawed frogs (Silurana tropicalis). Frogs were spawned and raised from fertilized embryo until sexual maturity in potassium perchlorate (KClO4)-treated water at different concentrations (0, 20, 53, and 107 μg/L). Developmental and reproductive indices - including adult morphology, androgen plasma levels, gonadal thyroid hormone- and sex steroid-related transcript levels, and sperm motility - were evaluated in male and female adult frogs. Female growth (e.g., body mass, snout-vent length, and hind limb length) was significantly reduced following chronic exposure to environmentally relevant concentrations of KClO4 resulting in females with morphometric indices similar to those of control males - indicating potential sex-specific sensitivities to KClO4. Changes to reproductive indices (i.e., plasma androgen levels, gonadal thyroid hormone- and sex steroid-related transcript levels, and sperm motility) were also observed in both sexes and suggest that KClO4 exposure may also have indirect secondary effects on the reproductive axes in male and female adult frogs. These effects were observed at concentrations at or below those reported in surface waters contaminated with ClO4- suggesting that this contaminant may have developmental and reproductive effects post-metamorphosis in natural amphibian populations.
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Affiliation(s)
| | | | - Valérie S Langlois
- Department of Biology, Queen's University, Kingston, ON, Canada; Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, Canada; Institut national de la recherche scientifique, INRS - Centre Eau Terre Environnement, Quebec, QC, Canada.
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Della Togna G, Gratwicke B, Evans M, Augustine L, Chia H, Bronikowski E, Murphy JB, Comizzoli P. Influence of extracellular environment on the motility and structural properties of spermatozoa collected from hormonally stimulated Panamanian Golden Frog (Atelopus zeteki). Theriogenology 2018; 108:153-160. [DOI: 10.1016/j.theriogenology.2017.11.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 11/22/2017] [Accepted: 11/23/2017] [Indexed: 01/21/2023]
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Abstract
Maintenance of optimal conditions such as water parameters, diet, and feeding is essential to a healthy Xenopus laevis and Xenopus tropicalis colony and thus to the productivity of the lab. Our prior husbandry experience as well as the rapid growth of the National Xenopus Resource has given us a unique insight into identifying and implementing these optimal parameters into our husbandry operations. Here, we discuss our standard operating procedures that will be of use to both new and established Xenopus facilities.
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Pearl E, Morrow S, Noble A, Lerebours A, Horb M, Guille M. An optimized method for cryogenic storage of Xenopus sperm to maximise the effectiveness of research using genetically altered frogs. Theriogenology 2017; 92:149-155. [PMID: 28237331 PMCID: PMC5340284 DOI: 10.1016/j.theriogenology.2017.01.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/26/2016] [Accepted: 01/04/2017] [Indexed: 02/06/2023]
Abstract
Cryogenic storage of sperm from genetically altered Xenopus improves cost effectiveness and animal welfare associated with their use in research; currently it is routine for X. tropicalis but not reliable for X. laevis. Here we compare directly the three published protocols for Xenopus sperm freeze-thaw and determine whether sperm storage temperature, method of testes maceration and delays in the freezing protocols affect successful fertilisation and embryo development in X. laevis. We conclude that the protocol is robust and that the variability observed in fertilisation rates is due to differences between individuals. We show that the embryos made from the frozen-thawed sperm are normal and that the adults they develop into are reproductively indistinguishable from others in the colony. This opens the way for using cryopreserved sperm to distribute dominant genetically altered (GA) lines, potentially saving travel-induced stress to the male frogs, reducing their numbers used and making Xenopus experiments more cost effective. Xenopus cryopreservation is robust using an optimized method. Success is dependent on the quality of animals from which the sperm are taken. Frozen sperm may now be used to distribute lines and wild-type male gametes around the world.
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Affiliation(s)
- Esther Pearl
- National Xenopus Resource, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Sean Morrow
- European Xenopus Resource Centre, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - Anna Noble
- European Xenopus Resource Centre, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - Adelaide Lerebours
- School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, UK
| | - Marko Horb
- National Xenopus Resource, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Matthew Guille
- European Xenopus Resource Centre, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, Portsmouth, PO1 2DT, UK; School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, UK.
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