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Browne RK, Luo Q, Wang P, Mansour N, Kaurova SA, Gakhova EN, Shishova NV, Uteshev VK, Kramarova LI, Venu G, Vaissi S, Taheri-Khas Z, Heshmatzad P, Bagaturov MF, Janzen P, Naranjo RE, Swegen A, Strand J, McGinnity D, Dunce I. Ecological Civilisation and Amphibian Sustainability through Reproduction Biotechnologies, Biobanking, and Conservation Breeding Programs (RBCs). Animals (Basel) 2024; 14:1455. [PMID: 38791672 PMCID: PMC11117272 DOI: 10.3390/ani14101455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 04/23/2024] [Accepted: 05/05/2024] [Indexed: 05/26/2024] Open
Abstract
Intergenerational justice entitles the maximum retention of Earth's biodiversity. The 2022 United Nations COP 15, "Ecological Civilisation: Building a Shared Future for All Life on Earth", is committed to protecting 30% of Earth's terrestrial environments and, through COP 28, to mitigate the effects of the climate catastrophe on the biosphere. We focused this review on three core themes: the need and potential of reproduction biotechnologies, biobanks, and conservation breeding programs (RBCs) to satisfy sustainability goals; the technical state and current application of RBCs; and how to achieve the future potentials of RBCs in a rapidly evolving environmental and cultural landscape. RBCs include the hormonal stimulation of reproduction, the collection and storage of sperm and oocytes, and artificial fertilisation. Emerging technologies promise the perpetuation of species solely from biobanked biomaterials stored for perpetuity. Despite significant global declines and extinctions of amphibians, and predictions of a disastrous future for most biodiversity, practical support for amphibian RBCs remains limited mainly to a few limited projects in wealthy Western countries. We discuss the potential of amphibian RBCs to perpetuate amphibian diversity and prevent extinctions within multipolar geopolitical, cultural, and economic frameworks. We argue that a democratic, globally inclusive organisation is needed to focus RBCs on regions with the highest amphibian diversity. Prioritisation should include regional and international collaborations, community engagement, and support for RBC facilities ranging from zoos and other institutions to those of private carers. We tabulate a standard terminology for field programs associated with RBCs for publication and media consistency.
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Affiliation(s)
| | - Qinghua Luo
- School of Biological Resources and Environmental Sciences, Jishou University, Jishou 416000, China; (Q.L.); (P.W.)
- College of Biological and Chemical Engineering, Changsha University, Changsha 410022, China
| | - Pei Wang
- School of Biological Resources and Environmental Sciences, Jishou University, Jishou 416000, China; (Q.L.); (P.W.)
- College of Biological and Chemical Engineering, Changsha University, Changsha 410022, China
| | - Nabil Mansour
- Fujairah Research Centre (FRC), Al-Hilal Tower 3003, Fujairah P.O. Box 666, United Arab Emirates;
| | - Svetlana A. Kaurova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino 142290, Russia; (S.A.K.); (E.N.G.); (N.V.S.); (V.K.U.)
| | - Edith N. Gakhova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino 142290, Russia; (S.A.K.); (E.N.G.); (N.V.S.); (V.K.U.)
| | - Natalia V. Shishova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino 142290, Russia; (S.A.K.); (E.N.G.); (N.V.S.); (V.K.U.)
| | - Victor K. Uteshev
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino 142290, Russia; (S.A.K.); (E.N.G.); (N.V.S.); (V.K.U.)
| | - Ludmila I. Kramarova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino 142290, Russia;
| | - Govindappa Venu
- Centre for Applied Genetics, Department of Zoology, Jnana Bharathi Campus, Bangalore University, Bengaluru 560056, India;
- Evolving Phylo Lab, Centre for Ecological Sciences, Indian Institute of Science, Bengaluru 560012, India
| | - Somaye Vaissi
- Department of Biology, Faculty of Science, Razi University, Kermanshah 57146, Iran; (S.V.); (Z.T.-K.)
| | - Zeynab Taheri-Khas
- Department of Biology, Faculty of Science, Razi University, Kermanshah 57146, Iran; (S.V.); (Z.T.-K.)
| | - Pouria Heshmatzad
- Department of Fisheries, Faculty of Fisheries and Environmental Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan 49138, Iran;
| | - Mikhail F. Bagaturov
- IUCN/SSC/Athens Institute for Education and Research/Zoological Institute RAS, St. Petersburg 199034, Russia;
| | - Peter Janzen
- Verband Deutscher Zoodirectoren/Justus-von-Liebig-Schule, 47166 Duisburg, Germany;
| | - Renato E. Naranjo
- Centro Jambatu de Investigación y Conservación de Anfibios, Fundación Jambatu, Giovanni, Farina 566 y Baltra, San Rafael, Quito 171102, Ecuador;
| | - Aleona Swegen
- School of Environmental and Life Sciences, College of Engineering, Science and Environment, University of Newcastle, Callaghan 2308, Australia;
| | - Julie Strand
- Department of Animal and Veterinary Science, Aarhus University, Blichers Alle 20, 8830 Tjele, Denmark;
| | - Dale McGinnity
- Ectotherm Department, Nashville Zoo at Grassmere, Nashville, TN 37211, USA;
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Coxe N, Liu Y, Arregui L, Upton R, Bodenstein S, Voss SR, Gutierrez-Wing MT, Tiersch TR. Establishment of a Practical Sperm Cryopreservation Pathway for the Axolotl ( Ambystoma mexicanum): A Community-Level Approach to Germplasm Repository Development. Animals (Basel) 2024; 14:206. [PMID: 38254376 PMCID: PMC10812443 DOI: 10.3390/ani14020206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/18/2023] [Accepted: 12/19/2023] [Indexed: 01/24/2024] Open
Abstract
The axolotl (Ambystoma mexicanum) draws great attention around the world for its importance as a biomedical research model, but housing and maintaining live animals is increasingly expensive and risky as new transgenic lines are developed. The goal of this work was to develop an initial practical pathway for sperm cryopreservation to support germplasm repository development. The present study assembled a pathway through the investigation of axolotl sperm collection by stripping, refrigerated storage in various osmotic pressures, cryopreservation in various cryoprotectants, and in vitro fertilization using thawed sperm. By the stripping of males, 25-800 µL of sperm fluid was collected at concentrations of 1.6 × 106 to 8.9 × 107 sperm/mL. Sperm remained motile for 5 d in Hanks' Balanced Salt Solution (HBSS) at osmolalities of 100-600 mOsm/kg. Sperm cryopreserved in 0.25 mL French straws at 20 °C/min in a final concentration of 5% DMFA plus 200 mM trehalose and thawed at 25 °C for 15 s resulted in 52 ± 12% total post-thaw motility. In six in vitro fertilization trials, 20% of eggs tested with thawed sperm continued to develop to stage 7-8 after 24 h, and a third of those embryos (58) hatched. This work is the first report of successful production of axolotl offspring with cryopreserved sperm, providing a general framework for pathway development to establish Ambystoma germplasm repositories for future research and applications.
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Affiliation(s)
- Nicholas Coxe
- Aquatic Germplasm and Genetic Resources Center, School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70820, USA (S.B.); (M.T.G.-W.)
| | - Yue Liu
- Aquatic Germplasm and Genetic Resources Center, School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70820, USA (S.B.); (M.T.G.-W.)
| | - Lucía Arregui
- Aquatic Germplasm and Genetic Resources Center, School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70820, USA (S.B.); (M.T.G.-W.)
| | - Rose Upton
- Aquatic Germplasm and Genetic Resources Center, School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70820, USA (S.B.); (M.T.G.-W.)
| | - Sarah Bodenstein
- Aquatic Germplasm and Genetic Resources Center, School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70820, USA (S.B.); (M.T.G.-W.)
- Louisiana Sea Grant College Program, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Steven Randal Voss
- Department of Neuroscience, Ambystoma Genetic Stock Center and Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536, USA
| | - Maria T. Gutierrez-Wing
- Aquatic Germplasm and Genetic Resources Center, School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70820, USA (S.B.); (M.T.G.-W.)
| | - Terrence R. Tiersch
- Aquatic Germplasm and Genetic Resources Center, School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70820, USA (S.B.); (M.T.G.-W.)
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3
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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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Taniguchi-Sugiura Y, Tanaka EM. Artificial Insemination in Axolotl. Methods Mol Biol 2023; 2562:417-423. [PMID: 36272091 DOI: 10.1007/978-1-0716-2659-7_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In axolotls (Ambystoma mexicanum), fertilization takes place internally. After courtship, the male axolotl deposits spermatophores, which the female takes up into her cloaca in order to fertilize eggs internally. The success of axolotl breedings is subject to several poorly understood factors including age, pairing, and genotype. In some cases, individuals are unable to breed naturally despite having significant scientific value. Assisted reproductive technologies represent one approach to maintaining stocks of such individuals, as well as supplementing natural breedings of laboratory stocks.Here, we describe a protocol for artificial insemination--an assisted reproductive technology in which sperm is extracted from a male and transferred into the female cloaca, thus mimicking natural fertilization in axolotls. We believe that this simple method can be applied to other salamander species that have internal fertilization and also help restore endangered wild populations.
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Affiliation(s)
| | - Elly M Tanaka
- IMP (Research Institute of Molecular Pathology), Vienna, Austria.
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5
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Yandulskaya AS, Monaghan JR. Establishing a New Research Axolotl Colony. Methods Mol Biol 2023; 2562:27-39. [PMID: 36272066 PMCID: PMC10948202 DOI: 10.1007/978-1-0716-2659-7_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The field of regenerative biology has taken a keen interest in the Mexican axolotl (Ambystoma mexicanum) over the past few decades, as this salamander successfully regenerates amputated limbs and injured body parts. Recent progress in research tool development has also made possible axolotl genetic manipulation and single-cell analysis, which will help understand the molecular mechanisms of complex tissue regeneration. To support the growing popularity of this model, we describe how to set up a new axolotl housing facility at a research laboratory. We also review husbandry practices for raising axolotls and using them in biological research, with a focus on diet, water quality, breeding, and anesthesia.
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Affiliation(s)
| | - James R Monaghan
- Department of Biology, Northeastern University, Boston, MA, USA.
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Browne RK, Kaurova SA, Vasudevan K, McGinnity D, Venu G, Gonzalez M, Uteshev VK, Marcec-Greaves R. Reproduction technologies for the sustainable management of Caudata (salamander) and Gymnophiona (caecilian) biodiversity. Reprod Fertil Dev 2022; 34:479-497. [PMID: 35157827 DOI: 10.1071/rd21356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 12/30/2021] [Indexed: 11/23/2022] Open
Abstract
We review the use of reproduction technologies (RTs) to support the sustainable management of threatened Caudata (salamanders) and Gymnophiona (caecilian) biodiversity in conservation breeding programs (CBPs) or through biobanking alone. The Caudata include ∼760 species with ∼55% threatened, the Gymnophiona include ∼215 species with an undetermined but substantial number threatened, with 80% of Caudata and 65% of Gymnophiona habitat unprotected. Reproduction technologies include: (1) the exogenous hormonal induction of spermatozoa, eggs, or mating, (2) in vitro fertilisation, (3) intracytoplasmic sperm injection (ICSI), (4) the refrigerated storage of spermatozoa, (5) the cryopreservation of sperm, cell or tissues, (6) cloning, and (7) gonadal tissue or cell transplantation into living amphibians to eventually produce gametes and then individuals. Exogenous hormone regimens have been applied to 11 Caudata species to stimulate mating and to 14 species to enable the collection of spermatozoa or eggs. In vitro fertilisation has been successful in eight species, spermatozoa have been cryopreserved in seven species, and in two species in vitro fertilisation with cryopreserved spermatozoa has resulted in mature reproductive adults. However, the application of RTs to Caudata needs research and development over a broader range of species. Reproduction technologies are only now being developed for Gymnophiona, with many discoveries and pioneering achievement to be made. Species with the potential for repopulation are the focus of the few currently available amphibian CBPs. As Caudata and Gymnophiona eggs or larvae cannot be cryopreserved, and the capacity of CBPs is limited, the perpetuation of the biodiversity of an increasing number of species depends on the development of RTs to recover female individuals from cryopreserved and biobanked cells or tissues.
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Affiliation(s)
- Robert K Browne
- Sustainability America, La Isla Road, Sarteneja, Corozal District, Belize
| | - Svetlana A Kaurova
- Institute of Cell Biophysics of the Russian Academy of Sciences, PSCBR RAS, Pushchino, Moscow Region 142290, Russia
| | - Karthikeyan Vasudevan
- Laboratory for the Conservation of Endangered Species, CSIR-Centre for Cellular and Molecular Biology, Hyderabad, Telangana 500048, India
| | - Dale McGinnity
- Ectotherm Department, Nashville Zoo at Grassmere, Nashville, TN 37211, USA
| | - Govindappa Venu
- Department of Zoology, Centre for Applied Genetics, Bangalore University, Jnana Bharathi Campus, Bengaluru, Karnataka 560056, India
| | - Manuel Gonzalez
- Departamento de Produccion Animal, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico
| | - Victor K Uteshev
- Institute of Cell Biophysics of the Russian Academy of Sciences, PSCBR RAS, Pushchino, Moscow Region 142290, Russia
| | - Ruth Marcec-Greaves
- National Amphibian Conservation Center Detroit Zoological Society, Detroit, MI, USA. Honduras Amphibian Rescue and Conservation Center, Oak Grove Missouri 64075
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Silla AJ, Calatayud NE, Trudeau VL. Amphibian reproductive technologies: approaches and welfare considerations. CONSERVATION PHYSIOLOGY 2021; 9:coab011. [PMID: 33763231 PMCID: PMC7976225 DOI: 10.1093/conphys/coab011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 01/29/2021] [Accepted: 02/07/2021] [Indexed: 06/12/2023]
Abstract
Captive breeding and reintroduction programs have been established for several threatened amphibian species globally, but with varied success. This reflects our relatively poor understanding of the hormonal control of amphibian reproduction and the stimuli required to initiate and complete reproductive events. While the amphibian hypothalamo-pituitary-gonadal (HPG) axis shares fundamental similarities with both teleosts and tetrapods, there are more species differences than previously assumed. As a result, many amphibian captive breeding programs fail to reliably initiate breeding behaviour, achieve high rates of fertilization or generate large numbers of healthy, genetically diverse offspring. Reproductive technologies have the potential to overcome these challenges but should be used in concert with traditional methods that manipulate environmental conditions (including temperature, nutrition and social environment). Species-dependent methods for handling, restraint and hormone administration (including route and frequency) are discussed to ensure optimal welfare of captive breeding stock. We summarize advances in hormone therapies and discuss two case studies that illustrate some of the challenges and successes with amphibian reproductive technologies: the mountain yellow-legged frog (Rana muscosa; USA) and the northern corroboree frog (Pseudophryne pengilleyi; Australia). Further research is required to develop hormone therapies for a greater number of species to boost global conservation efforts.
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Affiliation(s)
- Aimee J Silla
- Corresponding author: School of Earth, Atmospheric and Life Sciences, University of Wollongong, Northfields Ave, Wollongong, New South Wales 2522, Australia.
| | - Natalie E Calatayud
- Taronga Institute of Science and Learning, Taronga Conservation Society Australia, Taronga, Western Plains Zoo, Obley Rd, Dubbo, New South Wales 2830, Australia
- San Diego Zoo Global-Beckman Center for Conservation Research, San Pasqual Valley Rd, Escondido, CA 92027, USA
| | - Vance L Trudeau
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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Gillis AB, Guy EL, Kouba AJ, Allen PJ, Marcec-Greaves RM, Kouba CK. Short-term storage of tiger salamander (Ambystoma tigrinum) spermatozoa: The effect of collection type, temperature and time. PLoS One 2021; 16:e0245047. [PMID: 33428658 PMCID: PMC7799794 DOI: 10.1371/journal.pone.0245047] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 12/21/2020] [Indexed: 01/13/2023] Open
Abstract
The aims of this project were to characterize tiger salamander (Ambystoma tigrinum) spermatozoa motility over time, when excreted as either milt or spermic urine prior to packaging into a spermatophore, and to determine the effect of temperature on sperm motility. A split-plot design was utilized to assess the motility of the two pre-spermatophore sample types at two temperatures, 0°C and 20°C (n = 10 for each treatment). Spermiation was induced through exogenous hormone treatment of luteinizing hormone releasing hormone analog in order to collect both milt and spermic urine, which were evaluated for motility, divided into two separate aliquots, and subsequently stored in either an ice-bath (0°C) or on the benchtop (20°C). The decay rate of sperm motility was assessed by reevaluating subsamples at 0.5, 1, 2, 3, 5, 7, and 24 hours following the initial assessment. Results showed that sperm stored at 0°C had significantly higher progressive, non-progressive, and total motility for both sperm collection types over time. An interaction was found between collection type and time, with milt exhibiting lower initial motility that was more sustainable over time, compared to spermic urine. For both milt and spermic urine, motility decreased rapidly with storage duration, indicating samples should be used as soon as possible to maximize motility for in-vitro fertilization and cryopreservation. This is the first study to describe the differences in sperm motility between milt and spermic urine from an internally fertilizing caudate and demonstrates the benefits of near freezing temperatures on sperm longevity.
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Affiliation(s)
- Amanda B. Gillis
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, United States of America
| | - Emmet L. Guy
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, United States of America
| | - Andrew J. Kouba
- Department of Wildlife, Fisheries, and Aquaculture, Mississippi State University, Mississippi State, MS, United States of America
| | - Peter J. Allen
- Department of Wildlife, Fisheries, and Aquaculture, Mississippi State University, Mississippi State, MS, United States of America
| | - Ruth M. Marcec-Greaves
- National Amphibian Conservation Center, Detroit Zoological Society, Royal Oak, MI, United States of America
| | - Carrie K. Kouba
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, United States of America
- * E-mail:
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Guy EL, Gillis AB, Kouba AJ, Barber D, Poole V, Marcec-Greaves RM, Kouba CK. Sperm collection and cryopreservation for threatened newt species. Cryobiology 2020; 94:80-88. [PMID: 32437677 DOI: 10.1016/j.cryobiol.2020.04.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/13/2020] [Accepted: 04/13/2020] [Indexed: 11/19/2022]
Abstract
The aims of this project were to transfer hormone-induced spermiation and sperm cryopreservation protocols developed in the model salamander species, Ambystoma tigrinum, to three threatened newt species. Additionally, we tested if supplementation with trehalose or thawing at different temperatures impacts post-thaw sperm parameters. Hormone stimulation protocols were applied to male Notophthalmus meridionalis (N = 10), Neurergus kaiseri (N = 5) and Tylototriton kweichowensis (N = 6) with sperm collected periodically up to 24-28 h post-spermiation dose. Samples of adequate sperm concentration (>70%) were cryopreserved in solutions of 10% Me2SO + 1% BSA with or without a 10% trehalose cryodiluent. Frozen sperm samples were thawed at either 20 °C or 40 °C and examined for post-thaw motility parameters and abnormalities in head and tail structure. The spermiation response to exogenous hormone treatment was significantly different between newt species, with a success rate of 0% for N. kaiseri, 67% for T. kweichowensis, and 100% for N. meridionalis. Sperm concentration varied with time of collection after hormone administration in both T. kweichowensis and N. meridionalis. For N. meridionalis, structural abnormalities decreased in samples collected over the 24 h period (p < 0.0001) and a thaw temperature of 40 °C resulted in higher relative total sperm motility (p < 0.0001). This is the first study to describe the cryopreservation of sperm from two newt species and demonstrates the transferability of ART developed in a salamander to two newt species.
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Affiliation(s)
- Emmet L Guy
- Mississippi State University, Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State, MS, USA, 39762
| | - Amanda B Gillis
- Mississippi State University, Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State, MS, USA, 39762
| | - Andrew J Kouba
- Mississippi State University, Department of Wildlife, Fisheries, and Aquaculture, Mississippi State, MS, USA, 39762
| | - Diane Barber
- Fort Worth Zoo, Department of Ectotherms, Fort Worth, TX, USA, 76110
| | - Vicky Poole
- Fort Worth Zoo, Department of Ectotherms, Fort Worth, TX, USA, 76110
| | - Ruth M Marcec-Greaves
- National Amphibian Conservation Center, Detroit Zoological Society, Detroit, MI, USA, 48067
| | - Carrie K Kouba
- Mississippi State University, Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State, MS, USA, 39762.
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Della Togna G, Howell LG, Clulow J, Langhorne CJ, Marcec-Greaves R, Calatayud NE. Evaluating amphibian biobanking and reproduction for captive breeding programs according to the Amphibian Conservation Action Plan objectives. Theriogenology 2020; 150:412-431. [PMID: 32127175 DOI: 10.1016/j.theriogenology.2020.02.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 02/16/2020] [Indexed: 01/18/2023]
Abstract
The Amphibian Conservation Action Plan (ACAP), published in 2007, is a formal document of international significance that proposed eleven relevant actions for global amphibian conservation. Action seven of the ACAP document addresses the use of amphibian captive programs as a conservation tool. Appendix material under this action explores the potential use of Genome Resource Banking (biobanking) as an urgently needed tool for these captive programs. ACAP proposed twelve objectives for Genome Resource Banking which exhibit little emphasis on reproduction as a vital underlying science for amphibian Captive Breeding Programs (CBP's). Here we have reassessed the original twelve ACAP objectives for amphibian reproduction and biobanking for CBP's as a contribution to future ACAP review processes. We have reviewed recent advances since the original objectives, as well as highlighted weaknesses and strengths for each of these objectives. We make various scientific, policy and economic recommendations based on the current reality and recent advances in relevant science in order to inform future ACAP towards new global objectives. The number of amphibian CBP'S has escalated in recent years and reproductive success is not always easily accomplished. Increases in applied and fundamental research on the natural history and reproductive biology of these species, followed by the appropriate development and application of artificial reproductive technologies (ART's) and the incorporation of genome resource banks (GRB's), may turn CBP's into a more powerful tool for amphibian conservation.
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Affiliation(s)
- Gina Della Togna
- Universidad Interamericana de Panama, Dirección de Investigación, Campus Central, Avenida Ricardo J. Alfaro, Panama; Smithsonian Tropical Research Institute, Panama Amphibian Rescue and Conservation Project, Panama.
| | - Lachlan G Howell
- University of Newcastle, Conservation Biology Research Group, University Drive, Callaghan, NSW, 2308, Australia
| | - John Clulow
- University of Newcastle, Conservation Biology Research Group, University Drive, Callaghan, NSW, 2308, Australia
| | | | - Ruth Marcec-Greaves
- National Amphibian Conservation Center, Detroit Zoological Society, Royal Oak, MI, 48067, USA
| | - Natalie E Calatayud
- San Diego Zoo Institute for Conservation Research, San Pasqual Valley Road, Escondido, CA, 92027, USA; Taronga Institute of Science and Learning, Taronga Conservation Society Australia, Taronga Western Plains Zoo, Dubbo, NSW, 2830, Australia
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Sanor LD, Flowers GP, Crews CM. Multiplex CRISPR/Cas screen in regenerating haploid limbs of chimeric Axolotls. eLife 2020; 9:48511. [PMID: 31989926 PMCID: PMC6986871 DOI: 10.7554/elife.48511] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 01/06/2020] [Indexed: 01/04/2023] Open
Abstract
Axolotls and other salamanders can regenerate entire limbs after amputation as adults, and much recent effort has sought to identify the molecular programs controlling this process. While targeted mutagenesis approaches like CRISPR/Cas9 now permit gene-level investigation of these mechanisms, genetic screening in the axolotl requires an extensive commitment of time and space. Previously, we quantified CRISPR/Cas9-generated mutations in the limbs of mosaic mutant axolotls before and after regeneration and found that the regenerated limb is a highfidelity replicate of the original limb (Flowers et al. 2017). Here, we circumvent aforementioned genetic screening limitations and present methods for a multiplex CRISPR/Cas9 haploid screen in chimeric axolotls (MuCHaChA), which is a novel platform for haploid genetic screening in animals to identify genes essential for limb regeneration.
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Affiliation(s)
- Lucas D Sanor
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, United States
| | - Grant Parker Flowers
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, United States
| | - Craig M Crews
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, United States.,Department of Chemistry, Yale University, New Haven, United States.,Department of Pharmacology, Yale University, New Haven, United States
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12
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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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13
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Silla AJ, McFadden M, Byrne PG. Hormone-induced spawning of the critically endangered northern corroboree frog Pseudophryne pengilleyi. Reprod Fertil Dev 2019; 30:1352-1358. [PMID: 29694827 DOI: 10.1071/rd18011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/21/2018] [Indexed: 01/14/2023] Open
Abstract
Fundamental knowledge of the optimal hormone concentrations required to stimulate amplexus and spawning in breeding pairs of amphibians is currently lacking, hindering our understanding of the proximate mechanisms underpinning mating behaviour. The present study investigated the effects of: (1) the dose of a gonadotropin-releasing hormone analogue (GnRH-a) administered; (2) male-female hormone administration interval; and (3) topical application of GnRH-a, on spawning success in the northern corroboree frog. Administration of GnRH-a at doses of 0.5, 1.0 and 2.0μgg-1 were highly successful, with a significantly greater proportion of hormone-treated pairs ovipositing (89-100%) compared with the 0μgg-1 treatment (22%). Of the hormone-treated pairs, those receiving 0.5μgg-1 GnRH-a exhibited the highest fertilisation success (61%). Administration of GnRH-a to males and females simultaneously (0h) was more effective than injecting males either 48 or 24h before the injection of females. Overall, administration of GnRH-a was highly successful at inducing spawning in northern corroboree frogs. For the first time, we also effectively induced spawning following the topical application of GnRH-a to the ventral pelvic region. Topical application of GnRH-a eliminates the need for specialised training in amphibian injection, and will allow assisted reproductive technologies to be adopted by a greater number of captive facilities globally.
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Affiliation(s)
- Aimee J Silla
- Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Michael McFadden
- Herpetofauna Department, Taronga Conservation Society Australia, PO Box 20, Mosman, NSW 2088, Australia
| | - Phillip G Byrne
- Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
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14
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Gonadal steroids and energy availability during ovarian maturation stages of the Amazonian pirarucu Arapaima gigas (Teleostei: Osteoglossidae) in the wild. Comp Biochem Physiol A Mol Integr Physiol 2019; 230:106-114. [DOI: 10.1016/j.cbpa.2019.01.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 12/18/2018] [Accepted: 01/03/2019] [Indexed: 11/24/2022]
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Silla AJ, Byrne PG. The Role of Reproductive Technologies in Amphibian Conservation Breeding Programs. Annu Rev Anim Biosci 2018; 7:499-519. [PMID: 30359086 DOI: 10.1146/annurev-animal-020518-115056] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Anthropogenic environmental change has led to unprecedented rates of species extinction, presenting a major threat to global biodiversity. Among vertebrates, amphibians have been most severely impacted, with an estimated 41% of species now threatened with extinction. In response to this biodiversity crisis, a moral and ethical obligation exists to implement proactive interventionist conservation actions to assist species recovery and decelerate declines. Conservation breeding programs have been successfully established for several threatened amphibian species globally, aiming to prevent species' extinction by maintaining genetically representative assurance colonies ex situ while providing individuals for population augmentation, translocation, and reestablishment in situ. Reproductive technologies have enormous potential to enhance the propagation and genetic management of threatened species. In this review, we discuss the role of reproductive technologies in amphibian conservation breeding programs and summarize technological advancements in amphibian hormone therapies, gamete storage, and artificial fertilization.
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Affiliation(s)
- Aimee J Silla
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia; ,
| | - Phillip G Byrne
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia; ,
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Calatayud NE, Stoops M, Durrant BS. Ovarian control and monitoring in amphibians. Theriogenology 2017; 109:70-81. [PMID: 29325879 DOI: 10.1016/j.theriogenology.2017.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 12/01/2017] [Indexed: 12/29/2022]
Abstract
Amphibian evolution spans over 350 million years, consequently this taxonomic group displays a wide, complex array of physiological adaptations and their diverse modes of reproduction are a prime example. Reproduction can be affected by taxonomy, geographic and altitudinal distribution, and environmental factors. With some exceptions, amphibians can be categorized into discontinuous (strictly seasonal) and continuous breeders. Temperature and its close association with other proximate and genetic factors control reproduction via a tight relationship with circadian rhythms which drive genetic and hormonal responses to the environment. In recent times, the relationship of proximate factors and reproduction has directly or indirectly lead to the decline of this taxonomic group. Conservationists are tackling the rapid loss of species through a wide range of approaches including captive rescue. However, there is still much to be learned about the mechanisms of reproductive control and its requirements in order to fabricate species-appropriate captive environments that address a variety of reproductive strategies. As with other taxonomic groups, assisted reproductive technologies and other reproductive monitoring tools such as ultrasound, hormone analysis and body condition indices can assist conservationists in optimizing captive husbandry and breeding. In this review we discuss some of the mechanisms of ovarian control and the different tools being used to monitor female reproduction.
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Affiliation(s)
- N E Calatayud
- San Diego Zoo Global, Institute for Conservation Research, 15600 San Pasqual Valley Road, Escondido, CA 92027, United States.
| | - M Stoops
- Cincinnati Zoo & Botanical Garden, Center for Conservation and Research of Endangered Wildlife, 3400 Vine Street, Cincinnati, OH 45220, United States
| | - B S Durrant
- San Diego Zoo Global, Institute for Conservation Research, 15600 San Pasqual Valley Road, Escondido, CA 92027, United States
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Abstract
Reproduction of amphibians includes ovulation, spermiation, fertilization, oviposition, larval stage and development, and metamorphosis. A problem at any stage could lead to reproductive failure. To stimulate reproduction, environmental conditions must be arranged to simulate changes in natural habits. Reproductive life history is well documented in amphibians; a thorough knowledge of this subject will aid the practitioner in diagnosis and treatment. Technologies for artificial reproduction are developing rapidly, and some protocols may be transferable to privately kept or endangered species. Reproductive tract disorders are rarely described; no bacterial or viral diseases are known that specifically target the amphibian reproductive system.
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Ananjeva NB, Uteshev VK, Orlov NL, Gakhova EN. Strategies for conservation of endangered amphibian and reptile species. BIOL BULL+ 2015. [DOI: 10.1134/s1062359015050027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Clulow J, Trudeau VL, Kouba AJ. Amphibian Declines in the Twenty-First Century: Why We Need Assisted Reproductive Technologies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 753:275-316. [DOI: 10.1007/978-1-4939-0820-2_12] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Byrne PG, Silla AJ. Hormonal induction of gamete release, and in-vitro fertilisation, in the critically endangered southern corroboree frog, Pseudophryne corroboree. Reprod Biol Endocrinol 2010; 8:144. [PMID: 21114857 PMCID: PMC3014959 DOI: 10.1186/1477-7827-8-144] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 11/29/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Conservation Breeding Programs (CBP's) are playing an important role in the protection of critically endangered anuran amphibians, but for many species recruitment is not successful enough to maintain captive populations, or provide individuals for release. In response, there has been an increasing focus on the use of Assisted Reproductive Technologies (ART), including the administration of reproductive hormones to induce gamete release followed by in vitro fertilisation. The objective of this study was to test the efficacy of two exogenous hormones to induce gamete release, for the purpose of conducting in vitro fertilisation (IVF), in one of Australia's most critically endangered frog species, Pseudophryne corroboree. METHODS Male frogs were administered a single dose of either human chorionic gonadotropin (hCG) or luteinizing hormone-releasing hormone (LHRHa), while female frogs received both a priming and ovulatory dose of LHRHa. Spermiation responses were evaluated at 3, 7, 12, 24, 36, 48, 60 and 72 h post hormone administration (PA), and sperm number and viability were quantified using fluorescent microscopy. Ovulation responses were evaluated by stripping females every 12 h PA for 5 days. Once gametes were obtained, IVF was attempted by combining spermic urine with oocytes in a dilute solution of simplified amphibian ringer (SAR). RESULTS Administration of both hCG and LHRHa induced approximately 80% of males to release sperm over 72 h. Peak sperm release occurred at 12 h PA for hCG treated males and 36 h PA for LHRHa treated males. On average, LHRHa treated males released a significantly higher total number of live sperm, and a higher concentration of sperm, over a longer period. In female frogs, administration of LHRHa induced approximately 30% of individuals to release eggs. On average, eggs were released between 24 and 48 h PA, with a peak in egg release at 36 h PA. IVF resulted in a moderate percentage (54.72%) of eggs being fertilised, however all resultant embryos failed prior to gastrulation. CONCLUSIONS Hormone treatment successfully induced spermiation and ovulation in P. corroboree, but refinement of gamete induction and IVF techniques will be required before ART protocols can be used to routinely propagate this species.
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Affiliation(s)
- Phillip G Byrne
- School of Biological Sciences, Monash University, Melbourne Vic, Australia
| | - Aimee J Silla
- School of Animal Biology, University of Western Australia, Perth, Australia
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Silla AJ. Effects of luteinizing hormone-releasing hormone and arginine-vasotocin on the sperm-release response of Günther's Toadlet, Pseudophryne guentheri. Reprod Biol Endocrinol 2010; 8:139. [PMID: 21059269 PMCID: PMC2992061 DOI: 10.1186/1477-7827-8-139] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 11/08/2010] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Luteinizing hormone-releasing hormone (LHRH) is an exogenous hormone commonly used to induce spermiation in anuran amphibians. Over the past few decades, the LHRH dose administered to individuals and the frequency of injection has been highly variable. The sperm-release responses reported have been correspondingly diverse, highlighting a need to quantify dose-response relationships on a species-specific basis. This study on the Australian anuran Pseudophryne guentheri first evaluated the spermiation response of males administered one of five LHRHa doses, and second, determined whether AVT administered in combination with the optimal LHRHa dose improved sperm-release. METHODS Male toadlets were administered a single dose of 0, 1, 2, 4 or 8 micrograms/g body weight of LHRHa. A 4 micrograms/g dose of AVT was administered alone or in combination with 2 micrograms/g LHRHa. Spermiation responses were evaluated at 3, 7 and 12 h post hormone administration (PA), and sperm number and viability were quantified using fluorescent microscopy. RESULTS LHRHa administration was highly effective at inducing spermiation in P. guentheri, with 100% of hormone-treated males producing sperm during the experimental period. The number of sperm released in response to 2 micrograms/g LHRHa was greater than all other doses administered and sperm viability was highest in the 1 microgram/g treatment. The administration of AVT alone or in combination with LHRHa resulted in the release of significantly lower sperm numbers. CONCLUSION Overall, results from this study suggest that in P. guentheri, LHRHa is effective at inducing spermiation, but that AVT inhibits sperm-release.
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Affiliation(s)
- Aimee J Silla
- School of Animal Biology, The University of Western Australia, Perth, Australia.
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