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Maggs X. A synthetic review: natural history of amniote reproductive modes in light of comparative evolutionary genomics. Biol Rev Camb Philos Soc 2024. [PMID: 39300750 DOI: 10.1111/brv.13145] [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: 12/05/2022] [Revised: 09/02/2024] [Accepted: 09/04/2024] [Indexed: 09/22/2024]
Abstract
There is a current lack of consensus on whether the ancestral parity mode was oviparity (egg-laying) or viviparity (live-birth) in amniotes and particularly in squamates (snakes, lizards, and amphisbaenids). How transitions between parity modes occur at the genomic level has primary importance for how science conceptualises the origin of amniotes, and highly variable parity modes in Squamata. Synthesising literature from medicine, poultry science, reproductive biology, and evolutionary biology, I review the genomics and physiology of five broad processes (here termed the 'Main Five') expected to change during transitions between parity modes: eggshell formation, embryonic retention, placentation, calcium transport, and maternal-fetal immune dynamics. Throughout, I offer alternative perspectives and testable hypotheses regarding proximate causes of parity mode evolution in amniotes and squamates. If viviparity did evolve early in the history of lepidosaurs, I offer the nucleation site hypothesis as a proximate explanation. The framework of this hypothesis can be extended to amniotes to infer their ancestral state. I also provide a mechanism and hypothesis on how squamates may transition from viviparity to oviparity and make predictions about the directionality of transitions in three species. After considering evidence for differing perspectives on amniote origins, I offer a framework that unifies (i) the extended embryonic retention model and (ii) the traditional model which describes the amniote egg as an adaptation to the terrestrial environment. Additionally, this review contextualises the origin of amniotes and parity mode evolution within Medawar's paradigm. Medawar posited that pregnancy could be supported by immunosuppression, inertness, evasion, or immunological barriers. I demonstrate that this does not support gestation or gravidity across most amniotes but may be an adequate paradigm to explain how the first amniote tolerated internal fertilization and delayed egg deposition. In this context, the eggshell can be thought of as an immunological barrier. If serving as a barrier underpins the origin of the amniote eggshell, there should be evidence that oviparous gravidity can be met with a lack of immunological responses in utero. Rare examples of two species that differentially express very few genes during gravidity, suggestive of an absent immunological reaction to oviparous gravidity, are two skinks Lampropholis guichenoti and Lerista bougainvillii. These species may serve as good models for the original amniote egg. Overall, this review grounds itself in the historical literature while offering a modern perspective on the origin of amniotes. I encourage the scientific community to utilise this review as a resource in evolutionary and comparative genomics studies, embrace the complexity of the system, and thoughtfully consider the frameworks proposed.
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Affiliation(s)
- X Maggs
- Richard Gilder Graduate School at The American Museum of Natural History, 200 Central Park West, New York, NY, 10024, USA
- Christopher S. Bond Life Science Center at the University of Missouri, 1201 Rollins St, Columbia, MO, 65201, USA
- School of Life and Environmental Sciences at the University of Sydney, Heydon-Laurence Building A08, Sydney, NSW, 2006, Australia
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Perry SM, Mitchell MA. Reptile assisted reproductive technologies: can ART help conserve 300million years of evolution by preserving extant reptile biodiversity? Reprod Fertil Dev 2021; 34:385-400. [PMID: 34914885 DOI: 10.1071/rd21034] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 11/04/2021] [Indexed: 11/23/2022] Open
Abstract
Biodiversity loss is the greatest environmental problem threatening ecosystem, animal, and human health. Anthropogenic induced changes to climate, habitat, disease, species distributions, poaching, and unsustainable trade have accelerated extinction rates in all vertebrates, including reptiles. Preventing reptile extinctions will require humans to acknowledge these losses and develop ex situ and in situ plans to preserve them. Assisted reproductive technologies (ART) are management tools used to protect numerous vertebrate taxa; however, progress in developing ART for reptiles has lagged. Creating functional and sustainable reptile ART will strengthen our conservation capacity by capturing genetic material from select individuals to overcome natural or manmade boundaries. Utilising short-term gamete storage and genome resource banking, in conjunction with timed artificial insemination (AI) or ex ovo incubation, could lead to profound advances in reptile conservation, mitigating the loss of reptile biodiversity. In this article, we review ART reptile research completed since the 1970s. Topics include AI, hormonal control of reproduction, gamete collection, gamete storage, and genome resource banking. Additionally, we review the potential application of advanced reproductive methodologies, including in vitro/ex ovo fertilisation, intracytoplasmic sperm injection, cloning (somatic cell nuclear transfer), and genetic editing.
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Affiliation(s)
- Sean M Perry
- Department of Veterinary Clinical Sciences, Louisiana State University School of Veterinary Medicine, Skip Bertman Drive, Baton Rouge, LA, USA; and Mississippi Aquarium, 2100 E Beach Boulevard, Gulfport, MS, USA
| | - Mark A Mitchell
- Department of Veterinary Clinical Sciences, Louisiana State University School of Veterinary Medicine, Skip Bertman Drive, Baton Rouge, LA, USA
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Cruz-Cano NB, Sánchez-Rivera UÁ, Álvarez-Rodríguez C, Dávila-Govantes R, Cárdenas-León M, Martínez-Torres M. Sex steroids are correlated with environmental factors and body condition during the reproductive cycle in females of the lizard Sceloporus torquatus. Gen Comp Endocrinol 2021; 314:113921. [PMID: 34606744 DOI: 10.1016/j.ygcen.2021.113921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 09/25/2021] [Accepted: 09/29/2021] [Indexed: 12/06/2022]
Abstract
Reproduction is regulated by multiple factors that influence physiology and behavior to ensure the continuity of species. However, more work is needed to examine the complex relationships between environmental factors and endocrine transducers that modulate reproductive cycles, particularly in lizards. Here, we aimed to characterize the variation in plasma sex steroid levels in different stages of the reproductive cycle in the lizard Sceloporus torquatus and assess whether sex steroid levels were related to environmental factors (temperature, photoperiod, precipitation, and relative humidity) and body condition. Plasma concentrations of estradiol (E2) and progesterone (P4) from blood samples were quantified by enzyme-linked immunosorbent assay (ELISA) and radioimmunoanalysis (RIA), respectively. Our results indicate that sex steroid concentrations were positively related to follicular development but negatively related to temperature and precipitation. E2 increased as the follicles grew, and its concentrations were highest in the preovulatory phase. P4 showed a similar pattern and persisted during pregnancy. Changes in body condition were non-significant and mainly unrelated to the reproductive stage and plasma sex steroids. Our findings indicate that sex steroids change depending on the season and reproductive stage. We observed high concentrations of E2 and P4 in the late vitellogenic and preovulatory stages, probably because of their role in promoting vitellogenesis and ovulation. Additionally, we observed that follicular development is correlated with temperature and photoperiod. To better understand the mechanisms underlying reproduction, future studies of captive populations where environmental factors can be manipulated are needed.
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Affiliation(s)
- Norma Berenice Cruz-Cano
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Edificio D, 1° Piso, Circuito de Posgrados, Ciudad Universitaria, Coyoacán, Ciudad de México, México; Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México.
| | - Uriel Ángel Sánchez-Rivera
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México
| | - Carmen Álvarez-Rodríguez
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México
| | - Rodrigo Dávila-Govantes
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México
| | - Mario Cárdenas-León
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México; Laboratorio de Hormonas Proteicas, Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, C.P. 14080, Ciudad de México, México
| | - Martín Martínez-Torres
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México.
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Barbosa-Moyano H, Rodríguez-Chaparro S, Santos RLSR, Ramírez-Pinilla MP. Plasma estradiol and progesterone concentrations during the female reproductive cycle in a highly placentotrophic viviparous lizard, Mabuya sp. Gen Comp Endocrinol 2020; 295:113530. [PMID: 32526330 DOI: 10.1016/j.ygcen.2020.113530] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 05/13/2020] [Accepted: 06/03/2020] [Indexed: 11/25/2022]
Abstract
The neotropical genus Mabuya are obligate placentotrophic viviparous lizards, which have a short vitellogenesis that produces microlecithal oocytes and a prolonged time of gestation (9 to 10 months). The hormonal control of female reproductive activity during follicular growth and pregnancy has not been studied, although it is known that the corpus luteum can produce progesterone, but regresses early in pregnancy, being replaced in this function by the placenta. Through enzyme immunoassay (EIA) we measured the plasma concentrations of estradiol (E2) and progesterone (P4) in females of a population of Mabuya sp at different stages of their reproductive cycle. Previously, we confirmed the presence of P4 in plasma by high-performance liquid chromatography methods with diode-array detector ultraviolet (HPLC-DAD-UV). The average concentration values of E2 and P4 were compared among reproductive stages and their dynamics were related to what is known in other oviparous and viviparous amniotes. The plasma E2 concentrations of Mabuya sp. are below the levels found in other viviparous reptiles, probably related to the substantial reduction of its follicular growth phase. Its highest concentration was detected during vitellogenesis, related to its function in the growth and maturation of the ovarian follicles and oviduct preparation for pregnancy; lower levels were observed during pregnancy, but they increase at the end when a new vitellogenesis event begins and massive placental maternal-fetal nutrient transfer occurs. High concentrations of P4 were found during pregnancy, related to its function in the maintenance of the developing embryos within the oviduct. The highest levels of P4 were found at early gestation, then they descend from mid-gestation to the end of gestation. Although some characteristics of hormonal control related to the high level of placentotrophy were observed in this species, the changes in plasma sex steroid concentrations during the reproductive cycle in females of Mabuya sp. follow patterns seen in other viviparous amniotes.
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Affiliation(s)
- Heriberto Barbosa-Moyano
- Laboratorio de Biología Reproductiva de Vertebrados, Escuela de Biología, Universidad Industrial de Santander (UIS), Bucaramanga, Colombia
| | - Salomé Rodríguez-Chaparro
- Laboratorio de Biología Reproductiva de Vertebrados, Escuela de Biología, Universidad Industrial de Santander (UIS), Bucaramanga, Colombia
| | | | - Martha Patricia Ramírez-Pinilla
- Laboratorio de Biología Reproductiva de Vertebrados, Escuela de Biología, Universidad Industrial de Santander (UIS), Bucaramanga, Colombia.
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A comparison of uterine contractile responsiveness to arginine vasopressin in oviparous and viviparous lizards. J Comp Physiol B 2019; 190:49-62. [DOI: 10.1007/s00360-019-01254-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/03/2019] [Accepted: 12/08/2019] [Indexed: 12/13/2022]
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Genomic and transcriptomic investigations of the evolutionary transition from oviparity to viviparity. Proc Natl Acad Sci U S A 2019; 116:3646-3655. [PMID: 30808754 DOI: 10.1073/pnas.1816086116] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Viviparous (live-bearing) vertebrates have evolved repeatedly within otherwise oviparous (egg-laying) clades. Over two-thirds of these changes in vertebrate reproductive parity mode happened in squamate reptiles, where the transition has happened between 98 and 129 times. The transition from oviparity to viviparity requires numerous physiological, morphological, and immunological changes to the female reproductive tract, including eggshell reduction, delayed oviposition, placental development for supply of water and nutrition to the embryo by the mother, enhanced gas exchange, and suppression of maternal immune rejection of the embryo. We performed genomic and transcriptomic analyses of a closely related oviparous-viviparous pair of lizards (Phrynocephalus przewalskii and Phrynocephalus vlangalii) to examine these transitions. Expression patterns of maternal oviduct through reproductive development of the egg and embryo differ markedly between the two species. We found changes in expression patterns of appropriate genes that account for each of the major aspects of the oviparity to viviparity transition. In addition, we compared the gene sequences in transcriptomes of four oviparous-viviparous pairs of lizards in different genera (Phrynocephalus, Eremias, Scincella, and Sphenomorphus) to look for possible gene convergence at the sequence level. We discovered low levels of convergence in both amino acid replacement and evolutionary rate shift. This suggests that most of the changes that produce the oviparity-viviparity transition are changes in gene expression, so occasional reversals to oviparity from viviparity may not be as difficult to achieve as has been previously suggested.
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Duarte-Méndez M, Quintero-Silva J, Ramírez-Pinilla MP. Immunohistochemical localization of 3β-Hydroxysteroid dehydrogenase and progesterone receptors in the ovary and placenta during gestation of the placentotrophic lizard Mabuya sp (Squamata: Scincidae). Gen Comp Endocrinol 2018; 261:136-147. [PMID: 29477457 DOI: 10.1016/j.ygcen.2018.02.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 02/17/2018] [Accepted: 02/21/2018] [Indexed: 02/04/2023]
Abstract
In squamates, progesterone (P) plays a key role in the inhibition of uterine mobility during egg retention in oviparous species, and during gestation in viviparous species. The corpus luteum (CL) is the main organ responsible for the production of P; however, in some species, the CL degenerates early and the P needed for gestation maintenance should be produced in other tissues. Mabuya sp (Scincidae) is a viviparous lizard with a prolonged gestation, it produces microlecithal eggs and, consequently, has an obligate placentotrophy related with a highly complex placenta. Its CL degenerates at early stages of gestation and therefore, other sources of P should exist. The aim of this study was to determine and localize by immunohistochemistry the production of P by detection of the enzyme 3β-Hydroxysteroid dehydrogenase (3β-HSD) and P receptors (PR) during gestation in the ovary and placenta of Mabuya sp. Positive and negative control sections were used. The ovary of this species localizes 3β-HSD and PR in the same tissues. The CL of the ovaries of females at early stages of gestation were positive for both molecules, whereas they did not localize from mid gestation to the end of pregnancy. Previtellogenic and vitellogenic follicles labelled for both molecules in the follicular epithelium and thecae. The placenta of Mabuya sp. demonstrated the potential for P production from mid gestation to the end of gestation in the uterine and chorionic tissues. PR were located in the uterine tissues throughout gestation, with a decrease towards its completion. Western blot analysis confirmed the presence of 3β-HSD mainly in the ovary of early pregnant females and in the placental tissues at mid gestation stages. Therefore, the chorioallantoic placenta of Mabuya sp. has an endocrine function producing the P needed for gestation and replacing the CL from mid gestation to the end of pregnancy.
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Affiliation(s)
- Melissa Duarte-Méndez
- Laboratorio de Biología Reproductiva de Vertebrados, Escuela de Biología, Universidad Industrial de Santander, Bucaramanga Santander, Colombia
| | - Jennifer Quintero-Silva
- Laboratorio de Biología Reproductiva de Vertebrados, Escuela de Biología, Universidad Industrial de Santander, Bucaramanga Santander, Colombia
| | - Martha Patricia Ramírez-Pinilla
- Laboratorio de Biología Reproductiva de Vertebrados, Escuela de Biología, Universidad Industrial de Santander, Bucaramanga Santander, Colombia; Grupo de Estudios en Biodiversidad, Escuela de Biología, Universidad Industrial de Santander, Bucaramanga Santander, Colombia.
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Griffith OW, Brandley MC, Whittington CM, Belov K, Thompson MB. Comparative genomics of hormonal signaling in the chorioallantoic membrane of oviparous and viviparous amniotes. Gen Comp Endocrinol 2017; 244:19-29. [PMID: 27102939 DOI: 10.1016/j.ygcen.2016.04.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Revised: 01/17/2016] [Accepted: 04/16/2016] [Indexed: 01/13/2023]
Abstract
In oviparous amniotes (reptiles, birds, and mammals) the chorioallantoic membrane (CAM) lines the inside of the egg and acts as the living point of contact between the embryo and the outside world. In livebearing (viviparous) amniotes, communication during embryonic development occurs across placental tissues, which form between the uterine tissue of the mother and the CAM of the embryo. In both oviparous and viviparous taxa, the CAM is at the interface of the embryo and the external environment and can transfer signals from there to the embryo proper. To understand the evolution of placental hormone production in amniotes, we examined the expression of genes involved in hormone synthesis, metabolism, and hormone receptivity in the CAM of species across the amniote phylogeny. We collected transcriptome data for the chorioallantoic membranes of the chicken (oviparous), the lizards Lerista bougainvillii (both oviparous and viviparous populations) and Pseudemoia entrecasteauxii (viviparous), and the horse Equus caballus (viviparous). The viviparous taxa differ in their mechanisms of nutrient provisioning: L. bougainvillii is lecithotrophic (embryonic nourishment is provided via the yolk only), but P. entrecasteauxii and the horse are placentotrophic (embryos are nourished via placental transport). Of the 423 hormone-related genes that we examined, 91 genes are expressed in all studied species, suggesting that the chorioallantoic membrane ancestrally had an endocrine function. Therefore, the chorioallantoic membrane appears to be a highly hormonally active organ in all amniotes. No genes are expressed only in viviparous species, suggesting that the evolution of viviparity has not required the recruitment of any specific hormone-related genes. Our data suggest that the endocrine function of the CAM as a placental tissue evolved in part through co-option of ancestral gene expression patterns.
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Affiliation(s)
- Oliver W Griffith
- School of Life and Environmental Sciences, Heydon-Laurence Building, University of Sydney, Sydney, NSW 2006, Australia; Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, United States.
| | - Matthew C Brandley
- School of Life and Environmental Sciences, Heydon-Laurence Building, University of Sydney, Sydney, NSW 2006, Australia; New York University - Sydney, The Rocks, NSW 2000, Australia
| | - Camilla M Whittington
- School of Life and Environmental Sciences, Heydon-Laurence Building, University of Sydney, Sydney, NSW 2006, Australia; Faculty of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia
| | - Katherine Belov
- Faculty of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia
| | - Michael B Thompson
- School of Life and Environmental Sciences, Heydon-Laurence Building, University of Sydney, Sydney, NSW 2006, Australia
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Jones SM. Variations upon a theme: Australian lizards provide insights into the endocrine control of vertebrate reproductive cycles. Gen Comp Endocrinol 2017; 244:60-69. [PMID: 26342969 DOI: 10.1016/j.ygcen.2015.09.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Revised: 08/13/2015] [Accepted: 09/01/2015] [Indexed: 11/28/2022]
Abstract
Australian lizards exhibit a broad array of different reproductive strategies and provide an extraordinary diversity and range of models with which to address fundamental problems in reproductive biology. Studies on lizards have frequently led to new insights into hormonal regulatory pathways or mechanisms of control, but we have detailed knowledge of the reproductive cycle in only a small percentage of known species. This review provides an overview and synthesis of current knowledge of the hormonal control of reproductive cycles in Australian lizards. Agamid lizards have provided useful models with which to test hypotheses about the hormonal regulation of the expression of reproductive behaviors, while research on viviparous skinks is providing insights into the evolution of the endocrine control of gestation. However, in order to better understand the potential risks that environmental factors such as climate change and endocrine disrupting chemicals pose to our fauna, better knowledge is required of the fundamental characteristics of the reproductive cycle in a broader range of lizard species.
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Affiliation(s)
- Susan M Jones
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia.
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Martínez-Torres M, Salcedo-Álvarez M, Alvarez-Rodríguez C, Cárdenas-León M, Luis J, Moreno-Fierros L. Does the conceptus of the viviparous lizard Barisia imbricata imbricata participates in the regulation of progesterone production and the control of luteolysis? Anim Reprod Sci 2014; 148:212-20. [PMID: 24975848 DOI: 10.1016/j.anireprosci.2014.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 05/05/2014] [Accepted: 05/09/2014] [Indexed: 10/25/2022]
Abstract
It is generally accepted that progesterone is necessary to maintain gestation; however, the mechanisms that control the production of this steroid remain unknown. The corpus luteum has been assigned a central role in the maintenance of gestation based on its capacity to produce progesterone. A pseudopregnancy model was performed in a viviparous lizard, Barisia imbricata imbricata, to determine whether the absence of embryos would affect the pattern of progesterone production or the corpus luteum histology. Blood samples were obtained prior to ovulation and at 8, 16, and 24 weeks after ovulation (pseudopregnant and pregnant lizards), as well as one day after parturition (pregnant lizards) or 32 weeks after ovulation (pseudopregnant lizards). The corpus luteum was surgically removed one day after blood samples were obtained. Blood aliquots from nongravid females were obtained at similar timepoints. We found a significant reduction in plasma progesterone concentrations at 24 and 32 weeks post-ovulation in pseudopregnant lizards compared with those observed at similar times in intact pregnant lizards, whereas the progesterone levels in non-gestant lizards remained significantly lower than in either pseudopregnant or pregnant lizards. Moreover, we observed that the histological appearance of the corpus luteum from pseudogestational females (obtained 24 and 32 weeks post-ovulation) differed from the corpora lutea from lizards in late gestation and intact parturient lizards. These observations suggest that the conceptus participates in the regulation of progesterone production in late gestation and also in luteolysis control.
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Affiliation(s)
- Martín Martínez-Torres
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores, Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios no. 1, Los Reyes Iztacala A. P. 314, Tlalnepantla 54090, Estado de México CP, Mexico.
| | - Martha Salcedo-Álvarez
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores, Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios no. 1, Los Reyes Iztacala A. P. 314, Tlalnepantla 54090, Estado de México CP, Mexico
| | - Carmen Alvarez-Rodríguez
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores, Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios no. 1, Los Reyes Iztacala A. P. 314, Tlalnepantla 54090, Estado de México CP, Mexico
| | - Mario Cárdenas-León
- Laboratorio de Hormonas Proteicas, Departamento de Biología de la Reproducción, Instituto de Ciencias Médicas y de la Nutrición Salvador Subirán, México DF, Mexico
| | - Juana Luis
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores, Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios no. 1, Los Reyes Iztacala A. P. 314, Tlalnepantla 54090, Estado de México CP, Mexico
| | - Leticia Moreno-Fierros
- Laboratorio de Inmunidad en Mucosas-Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Los Reyes Iztacala AP 314, Tlalnepantla CP 54090, Estado de México, Mexico
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A review of the evolution of viviparity in squamate reptiles: the past, present and future role of molecular biology and genomics. J Comp Physiol B 2011; 181:575-94. [DOI: 10.1007/s00360-011-0584-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 04/19/2011] [Accepted: 04/20/2011] [Indexed: 12/06/2022]
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Martínez-Torres M, Hernández-Caballero ME, Luis-Díaz JA, Ortiz-López G, Cárdenas-León M, Moreno-Fierros L. Effects of luteectomy in early pregnancy on the maintenance of gestation and plasma progesterone concentrations in the viviparous temperate lizard Barisia imbricata imbricata. Reprod Biol Endocrinol 2010; 8:19. [PMID: 20184772 PMCID: PMC2838902 DOI: 10.1186/1477-7827-8-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Accepted: 02/25/2010] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Several studies have shown that the corpus luteum is the principal source of progesterone during the gravidity period in reptiles; however, its participation in the maintenance of gestation in the viviparous squamata is in dispute. The effects of ovariectomy or luteectomy vary according to the species and the time at which the procedure is performed. In this paper, we describe the effects of luteectomy during early pregnancy on the maintenance of gestation and progesterone concentrations in the temperate Mexican viviparous lizard Barisia imbricata imbricata. METHODS Twenty-four lizards were subjected to three different treatments: luteectomy, sham luteectomy or non-surgical treatment, and blood samples were obtained before and after surgical treatment at different stages of gestation to determine the effects of luteectomy on the maintenance of gestation and progesterone concentrations. RESULTS Spontaneous abortion was not observed in any of the females. However, luteectomy provoked abnormal parturition and a significant reduction in the number of young born alive. Parturition was normal in untreated females as well as those submitted to sham luteectomy. The surgical treatment also caused a significant reduction in progesterone concentrations in luteectomised females during early and middle gestation. However, no significant differences in hormone concentrations were observed among the three groups during late gestation or immediately post-parturition. CONCLUSIONS Our observations indicate that the presence of the corpus luteum is not necesary for the maintenance of gestation, but that it does participate in parturition control. Moreover, the corpus luteum of the viviparous lizard B. i. imbricata produces progesterone, at least during the first half of pregnancy, and that an extra-ovarian source of progesterone must maintain gestation in the absence of luteal tissue.
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Affiliation(s)
- Martín Martínez-Torres
- Laboratorio de Biología de la Reproducción-Unidad de Morfofisiología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Los Reyes Iztacala, AP 314, Tlalnepantla Estado de México CP 54090, México
| | - Marta E Hernández-Caballero
- Laboratorio de Biología de la Reproducción-Unidad de Morfofisiología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Los Reyes Iztacala, AP 314, Tlalnepantla Estado de México CP 54090, México
| | - Juana Alba Luis-Díaz
- Laboratorio de Biología de la Reproducción-Unidad de Morfofisiología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Los Reyes Iztacala, AP 314, Tlalnepantla Estado de México CP 54090, México
| | - Guadalupe Ortiz-López
- Laboratorio de Biología de la Reproducción Humana, Hospital Juárez de México, Secretaría de Salubridad y Asistencia. Avenida Instituto Politécnico Nacional # 5160, Magdalena de las Salinas, AP 07760, México DF, México
| | - Mario Cárdenas-León
- Laboratorio de Hormonas Proteicas, Departamento de Biología de la Reproducción, Instituto de Ciencias Médicas y de la Nutrición Salvador Subirán, México DF, México
| | - Leticia Moreno-Fierros
- Laboratorio de Inmunidad en Mucosas-Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Los Reyes Iztacala AP 314, Tlalnepantla Estado de México, CP 54090, México
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13
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Cartledge VA, Withers PC, Bradshaw SD. Water balance and arginine vasotocin in the cocooning frog Cyclorana platycephala (hylidae). Physiol Biochem Zool 2007; 81:43-53. [PMID: 18040971 DOI: 10.1086/523856] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2007] [Indexed: 11/03/2022]
Abstract
It is well established that forming a cocoon, for frog species capable of doing so, markedly reduces evaporative water loss; however, the capacity of cocooned frogs to maintain hydration during extended estivation is not well understood. The combined effects of long-term estivation and water loss were examined in the cocoon-forming species Cyclorana platycephala by assessing the hydration state of the frogs throughout a 15-mo estivation period. Frogs lost mass throughout the 15-mo period to a maximum of 36%+/-6.5% of their initial standard mass. Plasma osmolality reached maximal levels by the ninth month of estivation at 487 mOsm kg(-1) and then remained stable to the fifteenth month of estivation. Urine osmolality continued to increase to the fifteenth month of estivation, at which point plasma and urine concentrations were isosmotic. The use of bladder water to counter losses from circulation was indicated by the relatively slow rate of increase in plasma osmolality with mass loss and the progressive increase in urine osmolality. For estivating frogs, evidence was found for a possible threshold relationship between plasma osmolality and plasma arginine vasotocin (AVT) concentration. After estivation, plasma AVT concentrations decreased markedly after 15-mo estivators were placed in water for 2 h, suggesting that high levels of AVT may not be integral to rapid rehydration in this species.
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Affiliation(s)
- Victoria A Cartledge
- Zoology, School of Animal Biology, MO92, University of Western Australia, Crawley, Western Australia 6009, Australia.
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WHILE GM, JONES SM, WAPSTRA E. Birthing asynchrony is not a consequence of asynchronous offspring development in a non-avian vertebrate, the Australian skink Egernia whitii. Funct Ecol 2007. [DOI: 10.1111/j.1365-2435.2007.01272.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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15
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Bradshaw D, Ladyman M, Stewart T. Effect of hypernatraemia and the neurohypophysial peptide, arginine vasotocin (AVT) on behavioural thermoregulation in the agamid lizard, Ctenophorus ornatus. Gen Comp Endocrinol 2007; 150:34-40. [PMID: 16908023 DOI: 10.1016/j.ygcen.2006.07.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Revised: 07/06/2006] [Accepted: 07/07/2006] [Indexed: 11/20/2022]
Abstract
Hypernatraemia induced by chronic injections of sodium chloride provokes thermal depression in the agamid lizard, Ctenophorus (formerly Amphibolurus) ornatus, with a fall of two degrees Celsius in the mean body temperature selected behaviourally in a photo-thermal gradient. The placement of an electrolytic lesion in the base of the hypothalamus, designed to eliminate secretion of the neuropeptide arginine vasotocin (AVT), did not affect the lizards' thermoregulatory behaviour and their Preferred Body Temperature (PBT) was not significantly different from that of unoperated controls. Saline loading, however, did not induce thermal depression in these tract-operated individuals and their PBT was significantly higher than that of salt-loaded intact individuals. When AVT was injected into operated, salt-loaded, animals, however, thermal depression was observed, supporting the hypothesis that thermal depression brought about by hypernatraemia is mediated through the action of AVT. AVT similarly significantly depressed the PBT of injected intact individuals by 3.2 degrees C when compared with hydrated controls. Immunostaining for AVT confirmed that the lesions placed in the region of the median eminence virtually eliminated AVT located in the neurohypophysial tract, and the pars nervosa. This is the first report of an effect of this peptide on behavioural thermoregulation in a lizard.
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Affiliation(s)
- Don Bradshaw
- School of Animal Biology and Centre for Native Animal Research, The University of Western Australia, Perth, WA 6009, Australia.
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16
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Cartledge VA, Withers PC, McMaster KA, Thompson GG, Bradshaw SD. Water balance of field-excavated aestivating Australian desert frogs, the cocoon-formingNeobatrachus aquiloniusand the non-cocooningNotaden nichollsi(Amphibia: Myobatrachidae). J Exp Biol 2006; 209:3309-21. [PMID: 16916967 DOI: 10.1242/jeb.02393] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYBurrowed aestivating frogs of the cocoon-forming species Neobatrachus aquilonius and the non-cocooning species Notaden nichollsi were excavated in the Gibson Desert of central Australia. Their hydration state(osmotic pressure of the plasma and urine) was compared to the moisture content and water potential of the surrounding soil. The non-cocooning N. nichollsi was consistently found in sand dunes. While this sand had favourable water potential properties for buried frogs, the considerable spatial and temporal variation in sand moisture meant that frogs were not always in positive water balance with respect to the surrounding soil. The cocoon-forming N. aquilonius was excavated from two distinct habitat types, a claypan in which frogs had a well-formed cocoon and a dune swale where frogs did not have a cocoon. Cocoons of excavated frogs ranged in thickness from 19.4 μm to 55.61 μm and consisted of 81-229 layers. Cocooned claypan N. aquilonius were nearing exhaustion of their bladder water reserves and had a urine osmolality approaching that of the plasma. By contrast, non-cocooned N. aquilonius from the dune swale were fully hydrated, although soil moisture levels were not as high as calculated to be necessary to maintain water balance. Both species had similar plasma arginine vasotocin (AVT) concentrations ranging from 9.4 to 164 pg ml-1, except for one cocooned N. aquilonius with a higher concentration of 394 pg ml-1. For both species, AVT showed no relationship with plasma osmolality over the lower range of plasma osmolalities but was appreciably increased at the highest osmolality recorded. This study provides the first evidence that cocoon formation following burrowing is not obligatory in species that are capable of doing so, but that cocoon formation occurs when soil water conditions are more desiccating than for non-cocooned frogs.
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Affiliation(s)
- Victoria A Cartledge
- Zoology, School of Animal Biology, MO92, University of Western Australia, Crawley, Western Australia 6009, Australia.
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17
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Ford SS, Bradshaw SD. Kidney function and the role of arginine vasotocin in three agamid lizards from habitats of differing aridity in Western Australia. Gen Comp Endocrinol 2006; 147:62-9. [PMID: 16423351 DOI: 10.1016/j.ygcen.2005.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Revised: 11/27/2005] [Accepted: 12/01/2005] [Indexed: 11/30/2022]
Abstract
Western Australian agamid lizards are diverse and inhabit mesic to very arid areas of the state. Although reptilian kidneys are unable to elaborate hyperosmotic urine, we hypothesised that the renal system of lizards inhabiting arid areas would display an enhanced ability to conserve water under the control of the antidiuretic peptide hormone, arginine vasotocin (AVT). To examine this, the renal physiological and endocrine responses to osmotic challenge in three closely-related Australian agamid lizards inhabiting arid, semi-arid, and mesic environments were studied. The species studied were Pogona minor (mesic), Ctenophorus salinarum (semi-arid), and Ctenophorus nuchalis (arid). Circulating AVT was assayed and renal variables such as glomerular filtration rate (GFR), urine flow rate (V), and fractional reabsorption of filtrate FRH2O were measured in response to hypernatraemia, water load, and dehydration. Hypernatraemia and dehydration induced antidiuresis in all three species through similar mechanisms involving both glomerular and tubular responses. However, in salt-loaded P. minor the response was largely glomerular in nature, as FRH2O did not increase relative to the hydrated condition. The magnitude of the antidiuretic response was also greater in P. minor, indicating a greater sensitivity to osmotic challenge. Plasma concentrations of AVT were significantly correlated with FRH2O in P. minor (r2=0.38, P=0.025), but with GFR in C. nuchalis (r2=0.16, P=0.041). We found that the control and mechanisms of renal function among these lizards were largely similar, and there was little support for the hypothesis that arid lizards possess physiological adaptations not present in closely-related mesic lizards. Yet, differences remain in their response to hypernatraemia which may reflect the aridity of their different environments, or their varying habits.
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Affiliation(s)
- S S Ford
- School of Animal Biology (M092) and Centre for Native Animal Research, 35 Stirling Hwy, The University of Western Australia, Perth, WA 6009, Australia
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18
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Ladyman M, Bradshaw D, Bradshaw F. Physiological and hormonal control of thermal depression in the tiger snake, Notechis scutatus. J Comp Physiol B 2006; 176:547-57. [PMID: 16520994 DOI: 10.1007/s00360-006-0077-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 02/01/2006] [Accepted: 02/13/2006] [Indexed: 10/24/2022]
Abstract
Plasma sodium concentrations in field-caught Western tiger snakes, Notechis scutatus, from semi-arid Carnac Island (CI) varied seasonally, with snakes exhibiting significant hypernatraemia during summer and normal concentrations following autumn rain. In contrast, field-caught tiger snakes from a perennial fresh-water swamp (Herdsman Lake, HL) exhibited no significant increase in plasma sodium concentrations during summer. Laboratory-induced hypernatraemia caused thermal depression in both populations; there was a weak negative relationship between plasma sodium concentration and temperature selection that was significant for CI snakes. Hypernatraemia significantly elevated circulating concentrations of the neuropeptide arginine vasotocin (AVT) in both CI and HL snakes. CI snakes injected with a physiological dosage of AVT also evidenced thermal depression. Despite the positive correlation between AVT and both plasma sodium concentration and osmolality for laboratory snakes, field samples from CI snakes indicate that circulating levels of AVT may be influenced more by plasma osmolality than sodium levels. The data suggest that, in CI snakes, chronic dehydration in the field leads to hypernatraemia which may lead to elevated levels of AVT if plasma osmolality also increases. This will in turn invoke a depression in thermal behaviour that may improve the water economy and survival of snakes on semi-arid CI. Although HL snakes do not experience seasonal dehydration, physiological changes away from the stable homeostatic state appear to prompt the same behavioural shifts, illustrating the intrinsic nature of the thermal behaviour in different populations of the same species of snake.
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Affiliation(s)
- Mitchell Ladyman
- School of Animal Biology and Centre for Native Animal Research, The University of Western Australia, 6009, Perth, WA, Australia
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19
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Orgeig S, Daniels CB, Johnston SD, Sullivan LC. The pattern of surfactant cholesterol during vertebrate evolution and development: does ontogeny recapitulate phylogeny? Reprod Fertil Dev 2005; 15:55-73. [PMID: 12729504 DOI: 10.1071/rd02087] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2002] [Accepted: 01/21/2003] [Indexed: 11/23/2022] Open
Abstract
Pulmonary surfactant is a complex mixture of phospholipids (PLs), neutral lipids and proteins that lines the inner surface of the lung. Here it modulates surface tension, thereby increasing lung compliance and preventing the transudation of fluid. In humans, pulmonary surfactant is comprised of approximately 80% PLs, 12% neutral lipids and 8% protein. In most eutherian (i.e. placental) mammals, cholesterol (Chol) comprises approximately 8-10% by weight or 14-20 mol% of both alveolar and lamellar body surfactant. It is regarded as an integral component of pulmonary surfactant, yet few studies have concentrated on its function or control. The lipid composition is highly conserved within the vertebrates, except that surfactant of teleost fish is dominated by cholesterol, whereas tetrapod pulmonary surfactant contains a high proportion of disaturated phospholipids (DSPs). The primitive Australian dipnoan lungfish Neoceratodus forsterii demonstrates a 'fish-type' surfactant profile, whereas the other derived dipnoans demonstrate a surfactant profile similar to that of tetrapods. Homology of the surfactant proteins within the vertebrates points to a single evolutionary origin for the system and indicates that fish surfactant is a 'protosurfactant'. Among the terrestrial tetrapods, the relative proportions of DSPs and cholesterol vary in response to lung structure, habitat and body temperature (Tb), but not in relation to phylogeny. The cholesterol content of surfactant is elevated in species with simple saccular lungs or in aquatic species or in species with low Tb. The DSP content is highest in complex lungs, particularly of aquatic species or species with high Tb. Cholesterol is controlled separately from the PL component in surfactant. For example, in heterothermic mammals (i.e. mammals that vary their body temperature), the relative amount of cholesterol increases in cold animals. The rapid changes in the Chol to PL ratio in response to various physiological stimuli suggest that these two components have different turnover rates and may be packaged and processed differently. In mammals, the pulmonary surfactant system develops towards the end of gestation and is characterized by an increase in the saturation of PLs in lung washings and the appearance of surfactant proteins in amniotic fluid. In general, the pattern of surfactant development is highly conserved among the amniotes. This conservation of process is demonstrated by an increase in the amount and saturation of the surfactant PLs in the final stages (>75%) of development. Although the ratios of surfactant components (Chol, PL and DSP) are remarkably similar at the time of hatching/birth, the relative timing of the maturation of the lipid profiles differs dramatically between species. The uniformity of composition between species, despite differences in lung morphology, birthing strategy and relationship to each other, implies that the ratios are critical for the onset of pulmonary ventilation. The differences in the timing, on the other hand, appear to relate primarily to birthing strategy and the onset of air breathing. As the amount of cholesterol relative to the phospholipids is highly elevated in immature lungs, the pattern of cholesterol during development and evolution represents an example of ontogeny recapitulating phylogeny. The fact that cholesterol is an important component of respiratory structures that are primitive, when they are not in use or developing in an embryo, demonstrates that this substance has important and exciting roles in surfactant. These roles still remain to be explored.
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Affiliation(s)
- Sandra Orgeig
- Environmental Biology, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia.
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20
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Girling JE, Jones SM. In vitro progesterone production by maternal and embryonic tissues during gestation in the southern snow skink (Niveoscincus microlepidotus). Gen Comp Endocrinol 2003; 133:100-8. [PMID: 12899851 DOI: 10.1016/s0016-6480(03)00147-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The southern snow skink, Niveoscincus microlepidotus, has a protracted gestation, lasting approximately one year. Ovulation occurs in spring (November) and embryonic development is completed by early autumn (March); however, birth does not occur until the following spring. Previous studies have shown that plasma progesterone concentration peaks in preovulatory females (spring, October), remains high during early gestation, and decreases to basal by autumn. In vitro progesterone production by corpora lutea, non-luteal ovary, anterior oviduct, placental tissues, muscle, and embryonic adrenal-gonads from N. microlepidotus was assessed throughout gestation. Tissues were incubated with or without the precursor pregnenolone for 3h at 24 degrees C; the resulting media were analysed for progesterone using radioimmunoassay. In vitro progesterone production by corpora lutea in media only was high during early gestation, dropping to basal by autumn. Maternal adrenal glands produced progesterone in vitro in media only throughout gestation; however, the pattern of production did not correlate with plasma concentrations and may represent steroid that is normally converted to corticosterone. Non-luteal ovary, anterior oviduct, placental tissues, muscle, and embryonic adrenal-gonads produced minimal progesterone in media only, but were able to convert pregnenolone to progesterone; this suggests steroid metabolic capability within these tissues. Further research is needed to address the possible endocrine role(s) of placental and embryonic tissues during gestation in viviparous squamates.
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Affiliation(s)
- Jane E Girling
- School of Zoology, University of Tasmania, Box 252-05, 7001, Hobart, Tasmania, Australia.
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21
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Ladyman M, Bonnet X, Lourdais O, Bradshaw D, Naulleau G. Gestation, thermoregulation, and metabolism in a viviparous snake, Vipera aspis: evidence for fecundity-independent costs. Physiol Biochem Zool 2003; 76:497-510. [PMID: 13130429 DOI: 10.1086/376420] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2003] [Indexed: 11/03/2022]
Abstract
Oxygen consumption of gestating Aspic vipers, Vipera aspis (L.), was strongly dependent on body temperature and mass. Temperature-controlled, mass-independent oxygen consumption did not differ between pregnant and nonpregnant females. Maternal metabolism was not influenced during early gestation by the number of embryos carried but was weakly influenced during late gestation. These results differ from previous investigations that show an increase in mass-independent oxygen consumption in reproductive females relative to nonreproductive females and a positive relationship between metabolism and litter size. These data also conflict with published field data on V. aspis that show a strong metabolic cost associated with reproduction. We propose that, under controlled conditions (i.e., females exposed to precise ambient temperatures), following the mobilisation of resources to create follicles (i.e., vitellogenesis), early gestation per se may not be an energetically expensive period in reproduction. However, under natural conditions, the metabolic rate of reproductive females is strongly increased by a shift in thermal ecology (higher body temperature and longer basking periods), enabling pregnant females to accelerate the process of gestation. Combining both laboratory and field investigation in a viviparous snake, we suggest that reproduction entails discrete changes in the thermal ecology of females to provide optimal temperatures to the embryos, whatever their number. This results in the counterintuitive notion that metabolism may well be largely independent of fecundity during gestation, at least in an ectothermic reptile.
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Affiliation(s)
- Mitchell Ladyman
- Department of Zoology, University of Western Australia, Perth, Western Australia 6009, Australia.
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22
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Martínez-Torres M, Elena Hernández-Caballero M, Alvarez-Rodriguez C, Alba Luis-Díaz J, Ortíz-López G. Luteal development and progesterone levels during pregnancy of the viviparous temperate lizard Barisia imbricata imbricata (Reptilia: Anguidae). Gen Comp Endocrinol 2003; 132:55-65. [PMID: 12765644 DOI: 10.1016/s0016-6480(02)00607-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The relationship between plasma progesterone (P(4)) levels and the formation and degeneration of the corpus luteum (CL) was assessed monthly during gestation of the viviparous lizard Barisia imbricata imbricata. Histochemical activity of the delta(5-4) isomerase 3 beta-hydroxysteroide dehydrogenase (delta(5-4)3beta-HSD) in the luteal tissue and embryonic development were also observed. Females were gravid throughout winter and great part of spring (late November or early December until late May or early June). Corpus luteum development occurred in the first third of gestation (December and January) when the embryo reached developmental stage 27. Four sequential stages were identified during development and three stages during regression of the CL. The follicular and thecal tissue participated in the formation of the luteal cell mass. According to Xavier's classification, the CL of B. i. imbricata is a subtype from Type III. The activity of delta(5-4)3beta-HSD was observed mainly in the luteal cell mass. The first degenerative changes in the CL were observed in the early second third of the gestation and continued gradually until parturition. Progesterone levels increased in early pregnancy and reached its highest level during January (3.07+/-1.04 ng/ml) when mature corpora lutea were present. Gradual diminution in progesterone concentrations occurred in the second and last third of pregnancy and coincided with advanced degenerative changes and diminution in histochemical activity of delta(5-4)3beta-HSD in the luteal tissue. These observations suggest that the CL is the major source of progesterone during pregnancy of B. i. imbricata.
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Affiliation(s)
- Martín Martínez-Torres
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Los Reyes Iztacala A.P. 314, Tlalnepantla Estado de México C.P. 54110, Mexico.
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Girling JE. The reptilian oviduct: a review of structure and function and directions for future research. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 2002; 293:141-70. [PMID: 12115910 DOI: 10.1002/jez.10105] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The reptilian oviduct is a complex organ with a variety of functions (albumen production, eggshell production, placentation, oviposition or parturition, and sperm storage), depending on the parity mode of the species in question. These functions are under complex physiological control, the details of which are far from understood. The aims of this review are to summarise the information available concerning the structure and functions of the reptilian oviduct and to highlight areas in particular need of further research.
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Affiliation(s)
- Jane E Girling
- School of Zoology, University of Tasmania, Hobart, Tasmania, Australia 7001.
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Silveira PF, Breno MC, Martín del Río MP, Mancera JM. The distribution of vasotocin and mesotocin immunoreactivity in the brain of the snake, Bothrops jararaca. J Chem Neuroanat 2002; 24:15-26. [PMID: 12084408 DOI: 10.1016/s0891-0618(02)00016-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Polyclonal antibodies against vasotocin (AVT) and mesotocin (MST) were used to explore the distribution of these peptides in the brain of the snake Bothrops jararaca. Magnocellular AVT- and MST-immunoreactive (ir) perikarya were observed in the supraoptic nucleus (SON), being AVT-ir neurons more numerous. A portion of the SON, in the lateroventral margin of the diencephalon ventrally to optic tract, showed only AVT-ir perikarya and fibers. However, the caudal most portion displayed only mesotocinergic perikarya. Parvocellular and magnocellular AVT- and MST-ir perikarya were present in the paraventricular nucleus (PVN) being AVT-ir fibers more abundant than MST-ir. Vasotocinergic perikarya were also found in a dorsolateral aggregation (DLA) far from the PVN. Mesotocinergic perikarya were also present in the recessus infundibular nucleus and ependyma near to paraventricular organ. Nerve fibers emerging from supraoptic and paraventricular nuclei run along the diencephalic floor, internal zone of the median eminence (ME) to end in the neural lobe. Also a dense network of AVT- and MST-ir fibers was present in the external zone of the ME, close to the vessels of the hypophysial portal system. As a rule, all regions having vasotocinergic and mesotocinergic perikarya also showed immunoreactive fibers. Vasotocinergic and mesotocinergic fibers but not perikarya were found in the lamina terminalis (LT). Moreover AVT-ir fibers were present in the nucleus accumbens and MST-ir fibers in the septum. In mesencephalon and rhombencephalon MST-ir fibers were more numerous than AVT-ir fibers. Vasotocinergic and mesotocinergic fibers in extrahypothalamic areas suggest that these peptides could function as neurotransmitters and/or neuromodulators in the snake B. jararaca.
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Affiliation(s)
- P F Silveira
- Departamento de Biología Animal, Facultad de Ciencias del Mar, Universidad de Cádiz, 11510 Puerto Real Cádiz, Spain
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Johnston SD, Starrs AP, Daniels CB, Orgeig S. Ontogeny of the pulmonary surfactant and antioxidant enzyme systems in the viviparous lizard, Tiliqua rugosa. Physiol Biochem Zool 2002; 75:260-72. [PMID: 12177829 DOI: 10.1086/341999] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2002] [Indexed: 11/03/2022]
Abstract
The antioxidant enzyme (AOE) system protects the lung from oxidative damage. The pulmonary surfactant (PS) system lowers the interfacial pressure within the lung, improving lung compliance and aiding lung clearance. In mammals, the AOE and PS systems develop in tandem during the final 10%-20% of gestation. Here, we investigated the development of these systems in the viviparous skink, Tiliqua rugosa. The content of total phospholipid (PL), disaturated phospholipid (DSP), and cholesterol (Chol) increased in lung washings from foetal lizards with advancing gestational age. Similarly, the relative saturation of the PLs increased throughout gestation, with mid-stage 40 foetuses having a DSP/PL equivalent to newborns and adults. Maternal lizards had significantly less total PL, DSP, and Chol than nongravid and newborn lizards; however, the relative composition did not differ from nongravid animals. This presumably results from compression of the lungs under the bulk of the developing foetus. The Chol/PL and Chol/DSP ratios declined early in development such that mid-stage 40 embryos had comparable ratios to both newborns and adults. Thus, it appears that the PS system matures in a similar manner in skinks and in mammals. However, the composition of surfactant is complete some weeks before parturition, probably to enable improved survivorship of the precocial young in the event of premature birth. Unlike the surfactant lipids, the AOEs, catalase, superoxide dismutase, and glutathione peroxidase did not differ appreciably throughout gestation. It appears therefore that like the surfactant lipids the AOE system is in readiness for air breathing throughout the latter stages of gestation, possibly in preparation for premature birth. Unlike mammals, the PS and AOE systems develop independently from one another.
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Affiliation(s)
- Sonya D Johnston
- Department of Physiology, University of Adelaide, Adelaide, South Australia 5005, Australia
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Bennett EJ, Jones SM. Interrelationships among plasma progesterone concentrations, luteal anatomy and function, and placental ontogeny during gestation in a viviparous lizard (Niveoscincus metallicus: Scincidae). Comp Biochem Physiol A Mol Integr Physiol 2002; 131:647-56. [PMID: 11867290 DOI: 10.1016/s1095-6433(01)00495-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Plasma progesterone concentrations were measured at six stages of gestation in the viviparous lizard Niveoscincus metallicus. Anatomical and functional parameters of luteal activity were also investigated. The diameter of the corpus luteum (CL) decreased gradually though gestation, as did the diameter of the luteal cells. Major degenerative changes were observed in CLs post-partum. Plasma progesterone concentrations were basal both prior to, and just after, ovulation; a rapid increase occurred in early gestation. Plasma progesterone concentrations remained elevated until late gestation, but fell some 2 weeks before parturition. In vitro production of progesterone was greater in CLs in mid- than in late-gestation, and the addition of prostaglandin F(2alpha) to the incubation medium had no effect on progesterone production. Non-luteal ovarian tissue and adrenals produced progesterone, but at approximately one-tenth the rate of production by CLs. Temporal correlations between the plasma progesterone profile and stages of placental development were also assessed. The rise in plasma progesterone concentrations occurs before differentiation of the chorioallantoic placenta, but progesterone is still high when it degenerates. We conclude that the CLs are the major source of gestational progesterone in N. metallicus.
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Affiliation(s)
- Ellen J Bennett
- School of Zoology, University of Tasmania, GPO Box 252-05, Hobart, Tasmania 7001, Australia
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Edwards A, Jones SM. Changes in plasma progesterone, estrogen, and testosterone concentrations throughout the reproductive cycle in female viviparous blue-tongued skinks, Tiliqua nigrolutea (Scincidae), in Tasmania. Gen Comp Endocrinol 2001; 122:260-9. [PMID: 11356038 DOI: 10.1006/gcen.2001.7634] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Changes in mean plasma concentrations of progesterone (P4), estrogen (E), and testosterone (T) in a captive population of female viviparous skinks, Tiliqua nigrolutea, were examined. Reproductively active and quiescent individuals were present in the population concurrently, allowing a comparison between these two conditions. Mean plasma progesterone concentrations were basal (1-2 ng ml(-1)) until the start of gestation and peaked in the second trimester (12.7 +/- 1.27 ng ml(-1)), before falling significantly prior to parturition. An increase in mean plasma estrogen concentrations occurred coincident with the vitellogenic period; the mean plasma estrogen concentration peaked at 715.1 +/- 106.68 pg ml(-1) shortly before ovulation. Mean plasma testosterone concentrations in reproductively active females peaked in the periovulatory period (6.3 +/- 0.63 ng ml(-1)) and had returned to basal concentrations (<1 ng ml(-1)) 2 weeks later. Changes in mean plasma steroid concentrations were correlated with reproductive condition and are discussed in terms of potential in vivo steroid interactions and the multihormone control of reproduction.
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Affiliation(s)
- A Edwards
- School of Zoology, University of Tasmania, Hobart, Tasmania, 7001, Australia
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Bonnet X, Naulleau G, Bradshaw D, Shine R. Changes in plasma progesterone in relation to vitellogenesis and gestation in the viviparous snake Vipera aspis. Gen Comp Endocrinol 2001; 121:84-94. [PMID: 11161773 DOI: 10.1006/gcen.2000.7574] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Viviparity has arisen from oviparity on more than 100 independent occasions in squamate reptiles, providing an unique opportunity to investigate the ways in which endocrine control of gestation length has been modified by natural selection during this major transition in reproductive modes. Intuitively, the evolution of viviparity might be expected to involve an increasingly important role for the steroid hormone progesterone, rather than estradiol. Unfortunately, published data on this topic in snakes are scarce and often contradictory. Females of the viviparous snake Vipera aspis reproduce with a lower than annual frequency, providing the opportunity to examine steroid profiles simultaneously in vitellogenic, pregnant, and postparturient versus nonreproductive females. From 1990 to 1994, more than 500 blood samples were collected from more than 100 females. Progesterone, estradiol-17beta, and several plasma metabolites were assayed by radioimmunoassay and spectrophotometry. In contrast to earlier studies, we found significant differences between plasma progesterone levels in reproducing (10.5 +/- 9.1 ng ml(-1), N = 168) and nonreproducing (5.1 +/- 4.2 ng ml(-1), N = 121) females. Estradiol reached high levels during vitellogenesis (4.8 +/- 4.0 ng ml(-1), N = 16), and progesterone levels increased during gestation (from 3.7 ng ml(-1) before gestation to 18.7 ng ml(-1) at midgestation). However, experimental elevation of plasma progesterone levels with implants (up to 44.4 ng ml(-1)) did not modify plasma metabolite levels or delay parturition.
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Affiliation(s)
- X Bonnet
- Conseil Général des Deux-Sèvres, Niort, 79000, France
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29
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Abstract
Monogamy is relatively rarely reported in taxa other than birds. The reproductive system of many lizard species appears to involve multiple mating partners for both the male and the female. However, short-term monogamous relationships have been reported in some lizard species, either where the male defends a territory that is only occupied by a single adult female, or where males stay with females for a period of time after mating, apparently to guard against rival males. There are a few reported cases of more prolonged monogamous relationships in lizards, with the Australian sleepy lizard, Tiliqua rugosa, the best studied example. Adult males and females of this species form monogamous pairs for an extended period before mating each spring, and they select the same partner in successive years. The paper reviews possible functions of monogamy in this and other lizard species, and suggests that the additional perspective from studying lizards may enrich our overall understanding of monogamous behaviour.
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Silveira PF, Koike TI, Schiripa LN, Reichl AP, Magnoli FC, Mimura OM. Plasma arginine-vasotocin and hydroosmotic status of the terrestrial pit viper Bothrops jararaca. Gen Comp Endocrinol 1998; 109:336-46. [PMID: 9480741 DOI: 10.1006/gcen.1997.7037] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Peaks corresponding to arg-vasotocin obtained by HPLC from Sep-Pak C18 column extracts of Bothrops jararaca plasma were identified by radioimmunoassay and amino acid analysis. Plasma vasotocin and protein levels, osmolality, and L-cystine-di-beta-naphthylamidase were also compared in snakes under normal hydration conditions with or without chronic administration of vasotocin or in the presence of chronic hydroosmotic challenges. Sep-Pak C18 and radioimmunoassay were validated for the extraction and determination of this peptide, respectively (about 80% recovery). EDTA presented a protective action on this recovery compared to the use of heparin as anticoagulant for snake blood. A reduction of vasotocin content related to the time of incubation of this peptide added to snake plasma was detected by radioimmunoassay. Snake plasma activity also on L-cystine-di-beta-naphthylamide indicated that this vasotocin-destroying effect was due to hydrolysis by a cystine-aminopeptidase-like activity. Plasma levels of vasotocin revealed an unexpected dispersion and absent correlation with plasma levels of osmolality. Measurable vasotocin in a large number of snakes associated with lower levels of l-cystine-di-beta-naphthylamidase in acute than in chronic salt loading suggested the role of this enzyme activity in long-term regulation of the vasotocin system in this snake.
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Affiliation(s)
- P F Silveira
- Department of Physiology, Instituto de Biociências, São Paulo, 05503-900, Brazil
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31
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Jones SM, Wapstra E, Swain R. Asynchronous male and female gonadal cycles and plasma steroid concentrations in a viviparous lizard, Niveoscincus ocellatus (Scincidae), from Tasmania. Gen Comp Endocrinol 1997; 108:271-81. [PMID: 9356222 DOI: 10.1006/gcen.1997.6971] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The reproductive cycle in males of the skink, Niveoscincus ocellatus, is characterised by testicular development during summer, followed by mating in autumn. Plasma testosterone concentrations show a bimodal seasonal cycle, with the major peak (18.6 +/- 1.2 ng/ml) in late summer/autumn and a minor peak (7.4 +/- 1.0 ng/ml) at spring emergence. In contrast to the males, the females have a gonadal cycle in which mating is temporally dissociated from peak development of the gonads: ovulation occurs in spring and the young are born in summer. Fresh mating marks on females in spring indicate that at least part of the population mates for a second time after spring emergence. In females, plasma estradiol concentrations are significantly elevated (956 +/- 214 pg/ml) through vitellogenesis and are highest (1241 +/- 175 pg/ml) during the preovulatory phase. Plasma progesterone concentrations rise during gestation to 6.5 +/- 1.5 ng/ml, but fall in the final stage of gestation to 1.6 +/- 0.2 ng/ml. There is minimal atresia of vitellogenic follicles, suggesting that clutch size is determined when the follicles are recruited for vitellogenesis.
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Affiliation(s)
- S M Jones
- Department of Zoology, University of Tasmania, Hobart, TAS 7001, Australia
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32
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Silveira PF, Mimura OM. L-cystine-di-beta-naphthylamidase activity in plasma of the snake Bothrops jararaca after chronic challenges of water balance. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART C, PHARMACOLOGY, TOXICOLOGY & ENDOCRINOLOGY 1996; 114:185-192. [PMID: 8856957 DOI: 10.1016/0742-8413(96)00018-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Plasma protein, osmolality and L-cystine-di-beta-naphthylamidase activity were measured in Bothrops jararaca snakes submitted to normal hydration, water deprivation, water loading, salt loading or argvasotocin injections. Protein and osmolality were similar for male and female snakes in all treatments. Protein content was similar in all treatments, indicating the ability of the animals to maintain fluid balance between the vascular and extravascular compartment under osmotic challenges. Osmolality was increased in water-deprived and salt-loaded and was decreased in water-loaded animals compared with normally hydrated or argvasotocin-injected snakes. Enzymatic activity differed between males and females and was higher in salt-loaded females and in arg-vasotocin-injected females and males than in water-loaded snakes. A positive linear regression between osmolality and L-cystine-di-beta-naphthylamidase was obtained for female snakes (correlation coefficient = 0.6162, P < 0.01). The data show a role of arg-vasotocin in the consistent relationship between water balance and this sex-related aminopeptidase activity.
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Affiliation(s)
- P F Silveira
- Department of Physiology, Universidade de São Paulo, Brazil
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33
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Kulczykowska E. Solid-phase extraction of arginine vasotocin and isotocin in fish samples and subsequent gradient reversed-phase high-performance liquid chromatographic separation. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1995; 673:289-93. [PMID: 8611963 DOI: 10.1016/0378-4347(95)00276-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gradient high-performance liquid chromatography (HPLC) preceded by a solid-phase extraction (SPE) step is described for determining arginine vasotocin and isotocin, the neurohypophysial nonapeptides, in fish plasma samples. The combination of these two methods significantly improves the separation and increases the sensitivity of the assay. The proposed assay may be a useful alternative for analysis of similar nonapeptides in plasma without the use of radioisotopes, while taking into consideration a difference in detection sensitivity.
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Affiliation(s)
- E Kulczykowska
- Marine Biology Center of Polish Academy of Sciences, Gdynia, Poland
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34
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Pierson PM, Guibbolini ME, Lahlou B. Enzyme linked immunosorbent assay for the neurohypophyseal hormones arginine vasotocin and isotocin. JOURNAL OF IMMUNOASSAY 1995; 16:55-79. [PMID: 7775662 DOI: 10.1080/15321819508013549] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A competitive enzyme linked immunosorbent assay (ELISA) using new polyclonal antibodies was developed for the first time for each of two neurohypophyseal hormones: arginine vasotocin (AVT, ubiquitous in vertebrates) and isotocin (IT, restricted to teleost fish). The antibodies obtained were highly specific, showed no cross-reaction between the two peptides and were able to suppress the activity of the peptides in in vitro bioassays. An original feature of the assays was the covalent binding of the peptidic antigen to Covalink microplates. Competition was thereafter made between this bound antigen and the antigen in samples, for a fixed amount of the relevant antibody. Revelation used peroxidase-labeled antibodies. These ELISAs were sensitive enough to detect 1 ng/ml and 0.1 ng/ml for AVT and IT respectively. Moreover, for the first time, the two hormones were measured separately, each in the presence of the other, and shown to exist as circulating hormones in fish.
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Affiliation(s)
- P M Pierson
- Laboratoire de Physiologie Cellulaire et Comparée, CNRS ERS 78, Faculté des Sciences, Nice, France
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35
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Uchiyama M, Saito N, Shimada K, Murakami T. Pituitary and plasma arginine vasotocin levels in the lamprey, Lampetra japonica. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0300-9629(94)90267-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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36
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Propper CR, Jones RE, Dores RM, Lopez KH. Arginine vasotocin concentrations in the supraoptic nucleus of the lizard Anolis carolinensis are associated with reproductive state but not oviposition. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1992; 264:461-7. [PMID: 1460444 DOI: 10.1002/jez.1402640412] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Arginine vasotocin (AVT) is a neuropeptide involved in reproductive function in many nonmammalian vertebrates. We determined brain and plasma AVT concentrations during the estrous cycle and oviposition in the lizard Anolis carolinensis. There were no differences in AVT concentrations in the plasma or any brain region during the ovipositional sequence. However, we found that females with an egg in each oviduct and a large pre-ovulatory follicle (diameter > 4.5 mm) in one-ovary had significantly higher AVT concentrations in the supraoptic nucleus (SON) of the hypothalamus than did females with small pre-ovulatory follicles in both ovaries. In a second study, females with an egg in each oviduct and a large pre-ovulatory follicle had significantly greater AVT concentrations in the SON than females with only one oviductal egg and a large pre-ovulatory follicle or females with an egg in each oviduct and a small pre-ovulatory follicle in each ovary. Concentrations of AVT in other brain regions and in the plasma did not differ among these groups. Changes in steroid profiles during estrous and/or direct neural communication between the uterus, ovary, and brain may account for the changes in AVT concentrations seen in the supraoptic nucleus during the estrous cycle of Anolis carolinensis.
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Affiliation(s)
- C R Propper
- Department of EPO Biology, University of Colorado, Boulder 80309
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37
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Fergusson B, Bradshaw SD. In vitro uterine contractions in the viviparous lizard Tiliqua rugosa: effects of gestation and steroid pretreatment in vivo. Gen Comp Endocrinol 1992; 86:203-10. [PMID: 1601269 DOI: 10.1016/0016-6480(92)90103-q] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Uterine contractility was investigated in the viviparous lizard Tiliqua rugosa. Arginine vasotocin (AVT) induces rhythmic contractions in vitro in strips of uterine tissue from ovariectomized female T. rugosa. The strength of these contractions was related to the dosage of AVT and reduced by pretreatment in vivo with both progesterone and estradiol-17 beta. The frequency of spontaneous and AVT-induced contractions was enhanced by estradiol-17 beta pretreatment. The strength of AVT-induced contractions in pregnant females was not significantly different from that recorded in nonpregnant females. Spontaneous rhythmic contractions were present only in pregnant females. Ovariectomy did not affect either spontaneous or AVT-induced contractions in pregnant females. The data indicate that ovarian steroids modulate uterine contractility in T. rugosa. It is suggested that, following a decline in plasma progesterone levels, estrogen may be involved in the onset of parturition.
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Affiliation(s)
- B Fergusson
- Department of Zoology, University of Western Australia, Perth
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