1
|
Rosati L, Chianese T, De Gregorio V, Verderame M, Raggio A, Motta CM, Scudiero R. Glyphosate Interference in Follicular Organization in the Wall Lizard Podarcis siculus. Int J Mol Sci 2023; 24:ijms24087363. [PMID: 37108525 PMCID: PMC10138419 DOI: 10.3390/ijms24087363] [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: 03/06/2023] [Revised: 04/12/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Glyphosate (Gly) is a broad-spectrum herbicide widely used thanks to its high efficiency and low toxicity. However, evidence exists of its toxic effects on non-target organisms. Among these, the animals inhabiting agricultural fields are particularly threatened. Recent studies demonstrated that exposure to Gly markedly affected the morphophysiology of the liver and testis of the Italian field lizard Podarcis siculus. The present study aimed to investigate the effects of the herbicide on the female reproductive system of this lizard in order to have a full picture of Gly-induced reproductive impairment. The animals were exposed to 0.05 and 0.5 μg/kg of pure Gly by gavage for 3 weeks. The results demonstrated that Gly, at both doses tested, profoundly interfered with ovarian function. It induced germ cells' recruitment and altered follicular anatomy by anticipating apoptotic regression of the pyriform cells. It also induced thecal fibrosis and affected oocyte cytoplasm and zona pellucida organizations. At the functional levels, Gly stimulated the synthesis of estrogen receptors, suggesting a serious endocrine-disrupting effect. Overall, the follicular alterations, combined with those found at the level of the seminiferous tubules in males, suggest serious damage to the reproductive fitness of these non-target organisms, which over time could lead to a decline in survival.
Collapse
Affiliation(s)
- Luigi Rosati
- Department of Biology, University Federico II, Via Cintia 21, 80126 Napoli, Italy
| | - Teresa Chianese
- Department of Biology, University Federico II, Via Cintia 21, 80126 Napoli, Italy
| | - Vincenza De Gregorio
- Department of Biology, University Federico II, Via Cintia 21, 80126 Napoli, Italy
| | - Mariailaria Verderame
- Department of Human, Philosophic and Education Sciences (DISUFF), University of Salerno, 84084 Fisciano, Italy
| | - Anja Raggio
- Department of Biology, University Federico II, Via Cintia 21, 80126 Napoli, Italy
| | - Chiara Maria Motta
- Department of Biology, University Federico II, Via Cintia 21, 80126 Napoli, Italy
| | - Rosaria Scudiero
- Department of Biology, University Federico II, Via Cintia 21, 80126 Napoli, Italy
| |
Collapse
|
2
|
Knockout of the Glucocorticoid Receptor Impairs Reproduction in Female Zebrafish. Int J Mol Sci 2020; 21:ijms21239073. [PMID: 33260663 PMCID: PMC7729492 DOI: 10.3390/ijms21239073] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/24/2020] [Accepted: 11/26/2020] [Indexed: 12/21/2022] Open
Abstract
The pleiotropic effects of glucocorticoids in metabolic, developmental, immune and stress response processes have been extensively investigated; conversely, their roles in reproduction are still less documented. It is well known that stress or long-lasting therapies can cause a strong increase in these hormones, negatively affecting reproduction. Moreover, the need of glucocorticoid (GC) homeostatic levels is highlighted by the reduced fertility reported in the zebrafish glucocorticoid receptor mutant (nr3c1ia30/ia30) line (hereafter named gr−/−). Starting from such evidence, in this study, we have investigated the role of glucocorticoid receptor (Gr) in the reproduction of female zebrafish. Key signals orchestrating the reproductive process at the brain, liver, and ovarian levels were analyzed using a multidisciplinary approach. An impairment of the kiss-GnRH system was observed at the central level in (gr−/−) mutants as compared to wild-type (wt) females while, in the liver, vitellogenin (vtg) mRNA transcription was not affected. Changes were instead observed in the ovary, particularly in maturing and fully grown follicles (classes III and IV), as documented by the mRNA levels of signals involved in oocyte maturation and ovulation. Follicles isolated from gr−/− females displayed a decreased level of signals involved in the acquisition of competence and maturation, causing a reduction in ovulation with respect to wt females. Fourier transform infrared imaging (FTIRI) analysis of gr−/− follicle cytoplasm showed major changes in macromolecule abundance and distribution with a clear alteration of oocyte composition. Finally, differences in the molecular structure of the zona radiata layer of gr−/− follicles are likely to contribute to the reduced fertilization rate observed in mutants.
Collapse
|
3
|
Lindsay WR, Friesen CR, Sihlbom C, Bergström J, Berger E, Wilson MR, Olsson M. Vitellogenin offsets oxidative costs of reproduction in female painted dragon lizards. J Exp Biol 2020; 223:jeb221630. [PMID: 32393548 DOI: 10.1242/jeb.221630] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 05/05/2020] [Indexed: 12/18/2022]
Abstract
Vitellogenesis ('yolking' of follicles) is a bioenergetically costly stage of reproduction requiring enlargement of the liver to produce vitellogenin (VTG) yolk precursor proteins, which are transported and deposited at the ovary. VTG may, however, serve non-nutritive anti-oxidant functions, a hypothesis supported by empirical work on aging and other life-history transitions in several taxa. We test this hypothesis in female painted dragon lizards (Ctenophorus pictus) by examining covariation in VTG with the ovarian cycle, and relative to reactive oxygen species (ROS) including baseline superoxide (bSO). Plasma VTG decreased prior to ovulation, when VTG is deposited into follicles. VTG, however, remained elevated post-ovulation when no longer necessary for yolk provisioning and was unrelated to reproductive investment. Instead, VTG was strongly and positively predicted by prior bSO. ROS, in turn, was negatively predicted by prior VTG, while simultaneously sampled VTG was a positive predictor. These findings are consistent with the hypothesis that VTG functions as an anti-oxidant to counteract oxidative stress associated with vitellogenesis. The relationship between bSO and VTG was strongest in post-ovulatory females, indicating that its function may be largely anti-oxidant at this time. In conclusion, VTG may be under selection to offset oxidative costs of reproduction in egg-producing species.
Collapse
Affiliation(s)
- Willow R Lindsay
- Department of Biological and Environmental Sciences, University of Gothenburg, SE 405 30 Gothenburg, Sweden
| | - Christopher R Friesen
- School of Chemistry and Molecular Bioscience and Molecular Horizons Research Institute, The University of Wollongong, Wollongong, NSW 2522, Australia
| | - Carina Sihlbom
- Proteomics Core Facility of Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden
| | - Jörgen Bergström
- Proteomics Core Facility of Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden
| | - Evelin Berger
- Proteomics Core Facility of Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden
| | - Mark R Wilson
- School of Chemistry and Molecular Bioscience and Molecular Horizons Research Institute, The University of Wollongong, Wollongong, NSW 2522, Australia
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Mats Olsson
- Department of Biological and Environmental Sciences, University of Gothenburg, SE 405 30 Gothenburg, Sweden
- School of Chemistry and Molecular Bioscience and Molecular Horizons Research Institute, The University of Wollongong, Wollongong, NSW 2522, Australia
| |
Collapse
|
4
|
Fresnillo B, Belliure J, Gil D, Cuervo JJ. Hormonal control of seasonal color change in female spiny-footed lizards: an observational and experimental approach. Curr Zool 2019; 65:633-642. [PMID: 31857810 PMCID: PMC6911850 DOI: 10.1093/cz/zoz012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Accepted: 03/25/2019] [Indexed: 11/12/2022] Open
Abstract
Breeding coloration of females often signals aspects of their reproductive status, suggesting a link between color and sex steroid hormones. In this study, we examined the relationships between 2 sex steroid hormones (progesterone and β-estradiol) and reproductive coloration in female spiny-footed lizards Acanthodactylus erythrurus. We first explored natural variation in female plasma hormone levels and coloration during their reproductive cycle. β-estradiol was negatively related to brightness and positively related to red saturation, whereas progesterone was not significantly related to coloration. After identifying key relationships, plasma hormone concentrations were manipulated by creating 3 experimental female groups (β-estradiol-treated, progesterone-treated, and control), and the effects on coloration were monitored. β-estradiol-treated females, in which there was a rise in both β-estradiol and progesterone levels, lost their red coloration earlier than females in the other 2 experimental groups, whereas progesterone treatment had no significant effect on female coloration. Our results suggest that high levels of either β-estradiol alone or β-estradiol together with progesterone trigger the loss of red coloration in female spiny-footed lizards, and that progesterone alone does not affect coloration. We hypothesize that changes in female breeding color might be regulated by β-estradiol in species in which conspicuous coloration is displayed before ovulation, and by progesterone in species in which this color is displayed during gravidity.
Collapse
Affiliation(s)
- Belén Fresnillo
- Department of Life Sciences, Ecology Section, University of Alcalá, Madrid, Spain
- Department of Functional and Evolutionary Ecology, Estación Experimental de Zonas Áridas (CSIC), Carretera de Sacramento s/n, Almería, Spain
| | - Josabel Belliure
- Department of Life Sciences, Ecology Section, University of Alcalá, Madrid, Spain
| | - Diego Gil
- Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain
| | - José J Cuervo
- Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain
- Address correspondence to José J. Cuervo. E-mail:
| |
Collapse
|
5
|
Oguike M, Igboeli G, Ibe S, Ironkwe M. Physiological and endocrinological mechanisms associated with ovulatory cycle and induced-moulting in the domestic chicken – a Review. WORLD POULTRY SCI J 2019. [DOI: 10.1079/wps200574] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- M.A. Oguike
- Michael Okpara University of Agriculture, Umudike, P.M.B. 7267, Umuahia, Abia State, Nigeria
| | - G. Igboeli
- Department of Animal Science, University of Nigeria Nsukka, Nigeria
| | - S.N. Ibe
- Michael Okpara University of Agriculture, Umudike, P.M.B. 7267, Umuahia, Abia State, Nigeria
| | - M.O. Ironkwe
- Michael Okpara University of Agriculture, Umudike, P.M.B. 7267, Umuahia, Abia State, Nigeria
| |
Collapse
|
6
|
Health status of the lizard Podarcis siculus (Rafinesque-Schmaltz, 1810) subject to different anthropogenic pressures. C R Biol 2019; 342:81-89. [DOI: 10.1016/j.crvi.2019.04.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/04/2019] [Accepted: 04/04/2019] [Indexed: 12/24/2022]
|
7
|
Tripathy M, Rai U. Temporal expression and gonadotropic regulation of aromatase and estrogen receptors in the ovary of wall lizard, Hemidactylus flaviviridis: Correlation with plasma estradiol and ovarian follicular development. Steroids 2017; 128:23-31. [PMID: 29042199 DOI: 10.1016/j.steroids.2017.10.005] [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: 06/08/2017] [Revised: 09/09/2017] [Accepted: 10/11/2017] [Indexed: 11/26/2022]
Abstract
The current study in Indian wall lizard Hemidactylus flaviviridis for the first time demonstrates the reproductive phase-dependent expression pattern of aromatase (cyp19) and estrogen receptor subtypes (er-α and er-β) as well as their gonadotropic regulation in the ovary of a squamate. The expression of cyp19 remained low during regressed phase, increased markedly in recrudescent and declined sharply in breeding phase. Further, temporal profile of plasma estradiol 17-β (E2) was found to be relatively parallel to the expression pattern of ovarian cyp19. The expression pattern of estrogen receptors in the ovary showed subtype-specific variation along the reproductive cycle. Expression of ovarian er-α remained high from regressed to late recrudescence, while er-β expression that was low during regression dramatically increased with the initiation of follicular growth in early recrudescence and remained high until late recrudescence. Nonetheless, expression of both the receptors declined during breeding phase when ovary contained vitellogenic follicle. Regarding gonadotropic regulation, short-term treatment with Follicle stimulating hormone (3 injections of FSH) increased the ovarian expression of cyp19, er-α and er-β while prolongation of treatment (7 or 11 injections) resulted in a marked decrease in expression of these genes concomitant to formation of vitellogenic follicle. However, a marked increase in plasma E2 was recorded after 7 injections of FSH. The direct role of gonadotropin in regulation of cyp19 and estrogen receptors was established by an in vitro study where FSH upregulated the expression of these genes in all stages of ovarian follicles (early growing, previtellogenic and early vitellogenic) of wall lizards.
Collapse
Affiliation(s)
- Mamta Tripathy
- Department of Zoology, University of Delhi, Delhi 110007, India
| | - Umesh Rai
- Department of Zoology, University of Delhi, Delhi 110007, India.
| |
Collapse
|
8
|
Scudiero R, Verderame M, Motta CM, Simoniello P. Unravelling the Role of Metallothionein on Development, Reproduction and Detoxification in the Wall Lizard Podarcis sicula. Int J Mol Sci 2017; 18:ijms18071569. [PMID: 28753953 PMCID: PMC5536057 DOI: 10.3390/ijms18071569] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 07/13/2017] [Accepted: 07/16/2017] [Indexed: 12/22/2022] Open
Abstract
Metallothioneins (MTs) are an evolutionary conserved multigene family of proteins whose role was initially identified in binding essential metals. The physiological role of MT, however, has been revealed to be more complex than expected, since not only are MTs able to bind to toxic heavy metals, but many isoforms have shown specialized and alternative functions. Within this uncertainty, the information available on MTs in non-mammalian vertebrates, particularly in neglected tetrapods such as the reptiles, is even more scant. In this review, we provide a summary of the current understanding on metallothionein presence and function in the oviparous lizard Podarcis sicula, highlighting the results obtained by studying MT gene expression in most representative adult and embryonic tissues. The results demonstrate that in adults, cadmium induces MT transcription in a dose- and tissue-specific manner. Thus, the MT mRNAs appear, at least in some cases, to be an unsuitable tool for detecting environmental ion contamination. In early embryos, maternal RNAs sustain developmental needs for MT protein until organogenesis is well on its way. At this time, transcription starts, but again in a tissue- and organ-specific manner, suggesting an involvement in alternative roles. In conclusion, the spatiotemporal distribution of transcripts in adults and embryos definitively confirms that MT has deserved the title of elusive protein.
Collapse
Affiliation(s)
- Rosaria Scudiero
- Department of Biology, University Federico II, Via Mezzocannone 8, 80134 Napoli, Italy.
| | - Mariailaria Verderame
- Department of Biology, University Federico II, Via Mezzocannone 8, 80134 Napoli, Italy.
| | - Chiara Maria Motta
- Department of Biology, University Federico II, Via Mezzocannone 8, 80134 Napoli, Italy.
| | - Palma Simoniello
- Department of Sciences and Technology, University Parthenope, Centro Direzionale, Isola C4, 80143 Napoli, Italy.
| |
Collapse
|
9
|
Verderame M, Limatola E, Scudiero R. Ectopic synthesis of vitellogenin in testis and epididymis of estrogen-treated lizard Podarcis sicula. Gen Comp Endocrinol 2016; 235:57-63. [PMID: 27292789 DOI: 10.1016/j.ygcen.2016.06.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 06/06/2016] [Accepted: 06/08/2016] [Indexed: 12/18/2022]
Abstract
In oviparous vertebrates, vitellogenin (VTG) is the major yolk precursor synthesized in the liver of sexually mature females during the reproductive period. In males, the VTG gene is silent, but it may be activated by estradiol-17β (E2) or estrogen-like substances. Until now, extra-hepatic expression and synthesis of VTG after estrogen exposure has been reported only for aquatic vertebrates. This study demonstrates the ability of testis and epididymis of the terrestrial oviparous lacertid Podarcis sicula to synthesize VTG following E2 exposure. The results of in situ hybridization and immunohistochemistry analysis show the presence of both VTG mRNA and protein in these districts besides the known induction in the liver. The possible contemporaneous uptake of the E2-induced hepatic VTG by means of the specific vitellogenin receptor has been also evaluated. Finally, histological analysis shows that the E2-treatment during the mating season impairs spermatogenesis.
Collapse
Affiliation(s)
- Mariailaria Verderame
- Department of Biology, University Federico II, Via Mezzocannone 8, 80134 Napoli, Italy.
| | - Ermelinda Limatola
- Department of Biology, University Federico II, Via Mezzocannone 8, 80134 Napoli, Italy
| | - Rosaria Scudiero
- Department of Biology, University Federico II, Via Mezzocannone 8, 80134 Napoli, Italy
| |
Collapse
|
10
|
Brasfield SM, Talent LG, Janz DM. Reproductive and thyroid hormone profiles in captive Western fence lizards (Sceloporus occidentalis) after a period of brumation. Zoo Biol 2012; 27:36-48. [PMID: 19360602 DOI: 10.1002/zoo.20159] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Seasonal fluctuation in serum concentrations of sex steroid (testosterone [T] and 17beta-estradiol [E(2)]) and thyroid (triiodothyronine [T(3)] and thyroxine [T(4)]) hormones was determined in captive Western fence lizards (Sceloporus occidentalis). Samples were collected from male and female breeding pairs weekly for a 4-month period after their emergence from artificial brumation. Circulating levels of E(2) corresponded with the expected vitellogenic and ovulatory cycles in females, and surprisingly, E(2) in males followed a similar pattern, indicating a possible role in breeding behavior. Serum T was elevated in male lizards for the first 6 weeks after emergence from brumation, possibly related to an increase in the onset of active spermatogenesis. Thyroid hormones showed little cyclical activity throughout the breeding period, with the exception of small increases of T(3) at weeks 8 and 16, possibly implying an active role of this hormone with ovulation in females. Overall, these baseline hormone data are not only useful in developing this animal as a laboratory reptile model for assessment of endocrine-mediated toxicity, but also of value for understanding herpetological endocrinology and for application in the conservation of threatened species. Zoo Biol 27:36-48, 2008. (c) 2007 Wiley-Liss, Inc.
Collapse
|
11
|
Olsson M, Healey M, Perrin C, Wilson M, Tobler M. Sex-specific SOD levels and DNA damage in painted dragon lizards (Ctenophorus pictus). Oecologia 2012; 170:917-24. [PMID: 22700064 DOI: 10.1007/s00442-012-2383-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 05/24/2012] [Indexed: 11/24/2022]
Abstract
When groups of individuals differ in activities that may influence the production of reactive molecules, such as superoxide, we expect selection to result in congruent upregulation of antioxidant production in the group(s) most at risk of suffering concomitant erosion of essential tissue and biomolecules, such as DNA. We investigate this in a (near) annual lizard species, the Australian painted dragon (Ctenophorus pictus), in which males and females have fundamentally different lifestyles, with males being overtly conspicuous and aggressive, whereas females are placid and camouflaged. When kept in identical conditions to females in captivity, males had higher levels of superoxide dismutase (SOD) through the activity season, which is consistent with selection for a higher capacity of superoxide antioxidation and a lower level of DNA damage than females. Males, however, lacked the clear negative, linear relationship between SOD and DNA erosion observed in females, suggesting that female upregulation of SOD results in a more predictable antioxidation and a more immediate target for selection. Lastly, we analysed aspects of female reproduction from a DNA erosion perspective. Females closer to ovulation, hence with less remaining, circulating vitellogenin, had higher superoxide levels. Furthermore, a multiple regression analysis showed that females that produced more clutches over time suffered more DNA erosion, whereas females with higher SOD levels suffered less DNA erosion.
Collapse
Affiliation(s)
- Mats Olsson
- School of Biological Sciences, University of Sydney, Heydon-Lawrence Building, Sydney, NSW, 2006, Australia.
| | | | | | | | | |
Collapse
|
12
|
Al-Amri IS, Mahmoud IY, Waring CP, Alkindi AY, Khan T, Bakheit C. Seasonal changes in plasma steroid levels in relation to ovarian steroidogenic ultrastructural features and progesterone receptors in the house gecko, Hemidactylus flaviviridis, in Oman. Gen Comp Endocrinol 2012; 177:46-54. [PMID: 22387987 DOI: 10.1016/j.ygcen.2012.02.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 11/27/2011] [Accepted: 02/08/2012] [Indexed: 11/25/2022]
Abstract
A comprehensive study of the annual ovarian cycle in the house gecko, Hemidactylus flaviviridis, was conducted in Oman. Circulating estradiol (E(2)), progesterone (P), and testosterone (T) were measured during the active and inactive phases of the cycle. The steroid levels were related to the steroidogenic ultrastructural features such as the abundance of smooth endoplasmic reticulum (SER), the presence of cisternal whorls, and close association of lipid droplets with swollen vesiculated mitochondria and SER. The steroids were measured using a sensitive detection technique HPLC-MS/MS. E(2) levels began to rise in January at the onset of vitellogenesis and continued to rise between February and May relative to ovulation, postovulation, gravidity and oviposition. Afterwards, E(2) remained low during the inactive phase (June-December). P levels increased significantly in March and peaked in April, which coincided with luteinization. P levels began to decline relative to luteolysis (May-June). Afterwards, it remained low throughout the inactive phase. T levels rose significantly in March-April coinciding with vitellogenesis, but decreased rapidly and significantly in May and remained low during the inactive phase. Progesterone receptors (PR), identified using immunohistochemistry, were strongly expressed during the breeding period, but were absent during the non-breeding period. The appearance of the steroidogenic ultrastructural features in the preovulatory and lutein granulosa cells was correlated with the significant rise in the three steroid levels and the PR. As the steroid levels declined, the granulosa cells underwent a general degeneration and disruption of the associated steroidogenic features.
Collapse
Affiliation(s)
- I S Al-Amri
- Electron Microscopy Unit, Department of Pathology, College of Medicine & Health Sciences, Sultan Qaboos University, Al-Khod, Muscat, Oman.
| | | | | | | | | | | |
Collapse
|
13
|
Del Giudice G, Prisco M, Agnese M, Verderame M, Rosati L, Limatola E, Andreuccetti P. Effects of nonylphenol on vitellogenin synthesis in adult males of the spotted ray Torpedo marmorata. JOURNAL OF FISH BIOLOGY 2012; 80:2112-2121. [PMID: 22497418 DOI: 10.1111/j.1095-8649.2011.03172.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The aim of this investigation was to assess the effects of nonylphenol (NP), an oestrogen-like environmental pollutant, on the vitellogenin (VTG) synthesis in adult males of the aplacental viviparous cartilaginous fish Torpedo marmorata. The VTG recovery in males is considered a biomarker of xeno-oestrogenic pollution as this lipophosphoglycoprotein is physiologically induced by oestrogens only in females of oviparous and ovoviparous vertebrates. Using in situ hybridization and immunohistochemistry, T. marmorata males injected with nonylphenol showed the presence of VTG in the liver and the kidney. In particular, vtg messenger (m)RNA and VTG protein were expressed in the liver, whereas in the kidney cells only the presence of VTG was recorded. By contrast, no expression for VTG was detected in the testis. These results demonstrate that in T. marmorata NP induces the expression of vtg only in the liver; the presence of VTG in the kidney and its absence in the testis are discussed.
Collapse
Affiliation(s)
- G Del Giudice
- Department of Biological Sciences, Evolutionary and Comparative Biology Division, University of Naples Federico II, Naples, Italy
| | | | | | | | | | | | | |
Collapse
|
14
|
Verderame M, Angelini F, Limatola E. Expression of estrogen receptor alpha switches off secretory activity in the epididymal channel of the lizard Podarcis sicula. Mol Reprod Dev 2011; 79:107-17. [DOI: 10.1002/mrd.22005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 11/13/2011] [Indexed: 01/05/2023]
|
15
|
Del Giudice G, Prisco M, Agnese M, Verderame M, Limatola E, Andreuccetti P. Expression of vitellogenin in the testis and kidney of the spotted ray Torpedo marmorata exposed to 17β-estradiol. Gen Comp Endocrinol 2011; 174:318-25. [PMID: 21983423 DOI: 10.1016/j.ygcen.2011.09.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 09/20/2011] [Accepted: 09/22/2011] [Indexed: 10/17/2022]
Abstract
In vertebrates, the liver was long thought to be the only site of vitellogenin (Vtg) production, but recent studies demonstrated that Vtg is also expressed in extrahepatic districts. The aim of this paper is to assess, by in situ hybridization and immunohistochemistry, the expression of Vtg in the testis and kidney of Torpedo marmorata exposed to 17β-estradiol (E(2)). In treated samples vtg mRNA and Vtg were detected contemporaneously only in the testis; differently the kidney cells were positive to Vtg antibody, but negative to vtg mRNA. This is the first study to assess that male germ cells, after an exposure to E(2), synthesize Vtg in a stage-dependent manner. The presence of Vtg and the modifications observed in the kidney after E(2) treatment are discussed.
Collapse
Affiliation(s)
- Giuseppina Del Giudice
- Department of Biological Sciences, Evolutionary and Comparative Biology Division, University of Naples Federico II, Naples, Italy
| | | | | | | | | | | |
Collapse
|
16
|
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]
|
17
|
Verderame M, Prisco M, Andreuccetti P, Aniello F, Limatola E. Experimentally nonylphenol-polluted diet induces the expression of silent genes VTG and ERα in the liver of male lizard Podarcis sicula. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2011; 159:1101-1107. [PMID: 21397372 DOI: 10.1016/j.envpol.2011.02.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 12/21/2010] [Accepted: 02/10/2011] [Indexed: 05/30/2023]
Abstract
Endocrine Disruptor Chemicals (EDCs) with estrogen-like properties i.e nonylphenol (NP) induce vitellogenin (VTG) synthesis in males of aquatic and semi-aquatic species. In the oviparous species VTG is a female-specific oestrogen dependent protein. Males are unable to synthesize VTG except after E2 treatment. This study aimed to verify if NP, administered via food and water, is able to induce the expression of VTG even in males of vertebrates with a terrestrial habitat such as the lizard Podarcis. By means of ICC, ISH, W/B and ELISA we demonstrated that NP induces the presence of VTG in the plasma and its expression in the liver. VTG, undetectable in untreated males, reaches the value of 4.34 μg/μl in the experimental ones. Expression analysis and ISH in the liver showed that an NP-polluted diet also elicits the expression of ERα in the liver which is known to be related to VTG synthesis in Podarcis.
Collapse
Affiliation(s)
- Mariailaria Verderame
- Department of Biological Sciences, Evolutionary and Comparative Biology Division, University Federico II of Naples, Via Mezzocannone 8, 80134 Naples, Italy
| | | | | | | | | |
Collapse
|
18
|
|
19
|
Verderame M, Limatola E. Molecular identification of estrogen receptors (ERalpha and ERbeta) and their differential expression during VTG synthesis in the liver of lizard Podarcis sicula. Gen Comp Endocrinol 2010; 168:231-8. [PMID: 20417209 DOI: 10.1016/j.ygcen.2010.04.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2009] [Revised: 03/22/2010] [Accepted: 04/20/2010] [Indexed: 01/29/2023]
Abstract
In non-mammalian vertebrates yolk deposition in the oocytes is a hormone-dependent, gender-specific process. Produced by the ovary under gonadotropin stimulation, Estradiol 17-beta (E(2)) plays a key role in the liver synthesis of vitellogenin (VTG) which in turn is taken up by vitellogenic oocytes in the ovary. In many species a negative role in liver synthesis of VTG in females is also played by progesterone. Experimental administration of E(2) induces the expression of the VTG silent gene also in the liver of males of all the species studied. However, the role of the two isoforms of estrogen receptors, ERalpha and beta, in this process is still unclear. In order to elucidate what kind of ER is involved in the liver synthesis of VTG in the lizard Podarcis sicula, we obtained by means of RT-PCR two fragments of 430bp and 130bp from total ovarian mRNA, encoding respectively for ERalpha and ERbeta. Expression analysis of these two specific isoforms of ERs in the liver showed that in non-breeding females, and in wildlife untreated males only ERbeta is expressed. In breeding vitellogenic females and in E(2)-treated males both alpha and beta receptors are expressed. Furthermore, in females experimentally treated with progesterone during the breeding period, expression of ERalpha disappears. Conversely, treatment of females with E(2) in the non-breeding period induces expression of ERalpha. Immunohistochemical analysis and Western blotting showed that the presence of irVTG in liver and plasma is always parallel to hepatic expression of ERalpha in all the different experimental conditions. Our data strongly suggest that expression of ERalpha may be necessary for VTG synthesis in Podarcis. The possible modulatory role of ERbeta is also discussed.
Collapse
Affiliation(s)
- Mariailaria Verderame
- Department of Biological Sciences, Evolutionary and Comparative Biology Division, University of Naples Federico II, Via Mezzocannone 8, 80134 Naples, Italy.
| | | |
Collapse
|
20
|
Prisco M, Valiante S, Maddalena Di Fiore M, Raucci F, Del Giudice G, Romano M, Laforgia V, Limatola E, Andreuccetti P. Effect of 17beta-estradiol and progesterone on vitellogenesis in the spotted ray Torpedo marmorata Risso 1810 (Elasmobranchii: Torpediniformes): studies on females and on estrogen-treated males. Gen Comp Endocrinol 2008; 157:125-32. [PMID: 18555067 DOI: 10.1016/j.ygcen.2008.04.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 04/11/2008] [Accepted: 04/12/2008] [Indexed: 11/17/2022]
Abstract
The influence of 17beta-estradiol (E(2)) on vertebrate vitellogenesis is well ascertained. The aim of the present paper is to study the involvement of E(2) and progesterone (P) in the induction and regulation of vitellogenesis in females and experimental E(2)-treated males of Torpedo marmorata. We analyzed females in various stages of the reproductive cycle and E(2) experimentally treated males. The presence of vitellogenin was investigated in the plasma and in the liver by western blot and immunohistochemistry; its site of synthesis was investigated by in situ hybridization. The steroid levels in the plasma were measured by Enzyme Immunoassay. In treated males, E(2) induces in the liver the synthesis of VTG which is then secreted into the bloodstream as a 205-kDa polypeptide, the same that is found in the plasma of non-pregnant vitellogenic females. In females, E(2) is naturally present in the plasma and its level is correlated with VTG synthesis in the liver and with the female reproductive cycle. Indeed, large amounts of E(2) are only found in mature vitellogenic females, whose liver is involved in VTG synthesis and secretion. By contrast, small amounts of E(2) are evident in juveniles whose ovaries are lacking in vitellogenic follicles and in females preparing for ovulation. Low titers are also found in gravid females, whose liver is not engaged in VTG synthesis. We show that P, which is absent in untreated males and juvenile females, is evident in the blood serum of E(2)-treated males and sexually mature females. Interestingly, in treated males P appears in the plasma just 24h after the first injection of E(2) and its titer increases; a week after the last injections, the P level is similar to that recorded in non-gravid vitellogenic females. Finally, it is noteworthy that the highest titer of P was recorded in pregnant females. We demonstrate that in Torpedo vitellogenin synthesis, as in other vertebrates, is under the control of E(2) but also that this synthesis is probably under the control of progesterone.
Collapse
Affiliation(s)
- Marina Prisco
- Department of Biological Sciences, Evolutionary and Comparative Biology Division, University of Naples Federico II, Via Mezzocannone 8, 80134 Naples, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Wack CL, Fox SF, Hellgren EC, Lovern MB. Effects of sex, age, and season on plasma steroids in free-ranging Texas horned lizards (Phrynosoma cornutum). Gen Comp Endocrinol 2008; 155:589-96. [PMID: 18048031 DOI: 10.1016/j.ygcen.2007.10.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 10/02/2007] [Accepted: 10/04/2007] [Indexed: 11/25/2022]
Abstract
The Texas horned lizard (Phrynosoma cornutum) is protected in several states due to its apparently declining numbers; information on its physiology is therefore of interest from both comparative endocrine and applied perspectives. We collected blood samples from free-ranging P. cornutum in Oklahoma from April to September 2005, spanning their complete active period. We determined plasma concentrations of the steroids, progesterone (P), testosterone (T), and corticosterone (CORT) by radioimmunoassay following chromatographic separation and 17beta-estradiol (E2) by direct radioimmunoassay. T concentrations in breeding males were significantly higher than in non-breeding males. P showed no significant seasonal variation within either sex. CORT was significantly higher during the egg-laying season compared to breeding and non-breeding seasons for adult females and it was marginally higher in breeding than in non-breeding males (P=0.055). CORT concentrations also significantly increased with handling in non-breeding males and egg-laying females. Perhaps most surprisingly, there were no significant sex differences in plasma concentrations of P and E2. Furthermore, with respect to seasonal differences, plasma E2 concentrations were significantly higher in breeding females than in egg-laying or non-breeding females, and they were significantly higher in breeding than in non-breeding males. During the non-breeding season, yearling males exhibited higher E2 concentrations than adult males; no other differences between the steroid concentrations of yearlings and adults were detected. In comparison to other vertebrates, the seasonal steroid profile of P. cornutum exhibited both expected and unexpected patterns, and our results illustrate the value of collecting such baseline data as a springboard for appropriate questions for future research.
Collapse
Affiliation(s)
- Corina L Wack
- Department of Zoology, Oklahoma State University, 430 Life Sciences West, Stillwater, OK 74078, USA.
| | | | | | | |
Collapse
|
22
|
Thomson M, Herbert JF, Thompson MB. Tyrosine phosphorylated proteins in the reproductive tract of the viviparous lizard Eulamprus tympanum and the oviparous lizard Lampropholis guichenoti. Comp Biochem Physiol B Biochem Mol Biol 2006; 144:382-6. [PMID: 16750410 DOI: 10.1016/j.cbpb.2006.04.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 04/21/2006] [Accepted: 04/24/2006] [Indexed: 10/24/2022]
Abstract
Plastic changes occur in the morphology of the uterus at various stages of the reproductive cycle in both oviparous and viviparous lizards and these may be influenced by estrogen. Estrogen driven phosphorylation of effector proteins on tyrosine residues plays a major role in the plastic modulation of uterine anatomy and physiology in vertebrates. We used electrophoresis and Western blotting to characterize the phosphotyrosine protein profiles at various stages of the reproductive pathway in an oviparous lizard Lampropholis guichenoti and a viviparous lizard Eulamprus tympanum. L. guichenoti displayed major bands in the 200-35 kDa range and a triplet of bands of molecular masses 61 kDa, 52 kDa and 48 kDa in 50% of specimens and a 38 kDa band in all specimens. In contrast, E. tympanum samples all displayed a single major band at 40 kDa, which was significantly elevated at the early pregnancy stage. Somewhat paradoxically, the viviparous species, which has the more complex uterine epithelial changes during pregnancy, has the fewest phosphotyrosine bands, so how tyrosine phosphorylation is affected during the evolution of viviparity is not clear.
Collapse
Affiliation(s)
- Murray Thomson
- School of Biological Sciences, The University of Sydney, The Macleay Building A12, Sydney, NSW 2006, Australia.
| | | | | |
Collapse
|
23
|
Polzonetti-Magni AM, Mosconi G, Soverchia L, Kikuyama S, Carnevali O. Multihormonal control of vitellogenesis in lower vertebrates. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 239:1-46. [PMID: 15464851 DOI: 10.1016/s0074-7696(04)39001-7] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The comparative approach on how and when vitellogenesis occurs in the diverse reproductive strategies displayed by aquatic and terrestrial lower vertebrates is presented in this chapter; moreover, attention has been paid to the multihormonal control of hepatic vitellogenin synthesis as it is related to seasonal changes and to vitellogenin use by growing oocytes. The hormonal mechanisms regulating vitellogenin synthesis are also considered, and the effects of environmental estrogens on the feminization process in wildlife and humans have been reported. It is then considered how fundamental nonmammalian models appear to be, for vitellogenesis research, addressed to clarifying the yolkless egg and the evolution of eutherian viviparity.
Collapse
Affiliation(s)
- Alberta Maria Polzonetti-Magni
- Department of Comparative Morphology and Biochemistry, University of Camerino, V. Camerini 2, 62032 Camerino (MC), Italy
| | | | | | | | | |
Collapse
|
24
|
Lagarde F, Bonnet X, Henen B, Nagy K, Corbin J, Lacroix A, Trouvé C. Plasma steroid and nutrient levels during the active season in wild Testudo horsfieldi. Gen Comp Endocrinol 2003; 134:139-46. [PMID: 14511984 DOI: 10.1016/s0016-6480(03)00245-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Plasma concentrations of sex steroids (testosterone and progesterone), proteins (total protein and albumin), lipids (phospholipids, cholesterol, and triglycerides), and minerals (calcium and phosphorus) were measured in wild Testudo horsfieldi in Uzbekistan, during the short, 3-month activity period (March-May, 1998). Testosterone concentration in males was highest (52 ng/ml) when they had just emerged from brumation (hibernation) in mid-March, which was also the beginning of the mating period, and fell in April. In females, progesterone peaked in mid-April (at 10 ng/ml), just before ovulation of the first clutches at the end of April and beginning of May. Testosterone levels in females and progesterone levels in males were low (<3 ng/ml) throughout the activity period. In general, the plasma concentrations of proteins, lipids, and phosphorus increased slowly in males, but more rapidly in females, during the activity season. These increases were particularly strong in females in the second half of April, coinciding with the peaks in female hormone levels. The changes in plasma hormones and nutrients reflected the timing of the different behaviours. The four first weeks of above-ground activity (mid-March to mid-April) by males, when they had high testosterone levels, were primarily allocated to fighting other males, courtship, and mating, while females spent much of that time feeding. Thereafter, both sexes concentrated on feeding. Females were probably preparing to ovulate in late-April, when their progesterone levels were highest and when plasma nutrient levels increased considerably.
Collapse
Affiliation(s)
- Frédéric Lagarde
- Centre d'Etudes Biologiques de Chizé-CNRS, 79360 Villiers en Bois, France.
| | | | | | | | | | | | | |
Collapse
|
25
|
Herbst LH, Siconolfi-Baez L, Torelli JH, Klein PA, Kerben MJ, Schumacher IM. Induction of vitellogenesis by estradiol-17beta and development of enzyme-linked immunosorbant assays to quantify plasma vitellogenin levels in green turtles (Chelonia mydas). Comp Biochem Physiol B Biochem Mol Biol 2003; 135:551-63. [PMID: 12831775 DOI: 10.1016/s1096-4959(03)00141-6] [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: 10/27/2022]
Abstract
Treatment of juvenile green turtles (Chelonia mydas) with estradiol-17beta resulted in the induction of a 200 kDa plasma protein, consistent with vitellogenin (Vtg). The N-terminal 15 amino acids of the anion exchange purified protein shared sequence homologies with vitellogenins of several vertebrate species. Rabbit antiserum raised against purified Vtg recognized the plasma protein as well as several yolk proteins. Monoclonal antibody (Mab) HL1248, produced by inoculating mice with turtle yolk granules, showed specificity for plasma Vtg as well as a set of yolk proteins 120, 82, 43 and 32 kDa in size. The N-terminal 22 amino acids of the 43 kDa yolk protein was similar to the lipovitellin I subunit of Vtg of several vertebrate species. The peptide mass map of the 82 kDa yolk protein shared enough ions with that of purified plasma Vtg to support the conclusion that this protein was derived from plasma Vtg. Taken together, these results validate the specificity of Mab HL1248 for Vtg. Using purified Vtg concentration standards, competition and antigen capture enzyme-linked immunosorbant assays (ELISAs) were shown to quantitatively detect Vtg in green turtle plasma. Pre-induced plasma of juvenile turtles had Vtg levels of 2-4 micrograms/ml whereas post-estradiol exposure samples had 38-40 mg/ml. The plasma Vtg concentration of a nesting female turtle was 4.6 mg/ml, approximately 20-fold higher than that of a non-nesting adult female. The antigen capture ELISA will be useful in population studies of this endangered species, to detect vitellogenesis in females that will nest in a given year and to detect inappropriate Vtg levels in turtles exposed to xenoestrogens.
Collapse
Affiliation(s)
- Lawrence H Herbst
- Department of Pathology, Albert Einstein College of Medicine, 10461, Bronx, NY, USA.
| | | | | | | | | | | |
Collapse
|
26
|
Edwards A, Jones SM, Davies NW. A possible alternative to 17beta-estradiol in a viviparous lizard, Tiliqua nigrolutea. Gen Comp Endocrinol 2002; 129:114-21. [PMID: 12441121 DOI: 10.1016/s0016-6480(02)00523-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have detected an unusual polar steroid as a major end product of gonadal steroid biosynthesis in male and female blotched blue-tongued lizards, Tiliqua nigrolutea. In an investigation of the steroidogenic pathways in blue-tongued lizards, we incubated gonads of both male and female lizards with tritiated pregnenolone and identified the products of steroid biosynthesis using thin layer chromatography and high performance liquid chromatography with radiometric detection: gonads from both reproductively active and quiescent lizards were examined. The proportion of total radioactive substrate converted to the unknown polar steroid was greater in individuals with hypertrophied gonads (males (N=4) 28.1%; females (N=4) 45.3%) than in those with regressed gonads (males (N=4) 5.9%; females (N=4) 33.3%). Properties of the unknown steroid were identical across all incubations. Incubation time-course information, thin layer and high performance liquid chromatography properties of the polar steroid are presented. The steroid is more polar than 17beta-estradiol, which was not detected, but less polar than all tri-hydroxylated estrogens to which it was compared. The possibility of an alternative estrogen to 17beta-estradiol in some reptiles is discussed.
Collapse
Affiliation(s)
- Ashley Edwards
- School of Zoology, University of Tasmania, GPO Box 252-05, Hobart, Tasmania 7001, Australia.
| | | | | |
Collapse
|
27
|
Rosanova P, Romano M, Marciano R, Anteo C, Limatola E. Vitellogenin precursors in the liver of the oviparous lizard, Podarcis sicula. Mol Reprod Dev 2002; 63:349-54. [PMID: 12237951 DOI: 10.1002/mrd.90019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In reptiles, as in the other oviparous vertebrates, vitellogenin (VTG) synthesis is stimulated in the liver by ovarian estrogens. In this article, the presence of VTG precursors was detected in liver subcellular fractions of the oviparous lizard, Podarcis sicula, in the reproductive period. The rough endoplasmic reticulum (RER) and the smooth microsomal fraction (SMF), which includes smooth endoplasmic reticulum and Golgi complex, were separated by means of two different sucrose gradients. The successful separation was controlled at the electron microscope. The contents of the different compartments were extracted by means of n-octyl-beta-D-glucopiranoside detergent and subjected to SDS-PAGE. Western Blotting with homologous anti/VTG antibody revealed two immunoreactive proteins of about 84 and 70 kDa in the RER, and four proteins of about 180, 150, 60, 50 kDa in the SMF; all these proteins appeared phosphorylated and glycosylated. The differences in the molecular weight of these VTG precursors are discussed.
Collapse
Affiliation(s)
- Patrizia Rosanova
- Department of Evolutionary and Comparative Biology, University Federico II, Napoli, Italy
| | | | | | | | | |
Collapse
|
28
|
Romano M, Rosanova P, Anteo C, Limatola E. Lipovitellins and phosvitins of the fertilized eggs during embryo growth in the oviparous lizard Podarcis sicula. Mol Reprod Dev 2002; 63:341-8. [PMID: 12237950 DOI: 10.1002/mrd.90018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In the lizard Podarcis sicula, the major vitellogenin (VTG)-derived yolk proteins, lipovitellins and phosvitins, were extracted from the yolk globules of laid and fertilized eggs at different periods of incubation up to 44 days close to hatching. Embryonic development was almost over at this time. Yolk proteins were isolated by precipitation in saturated (NH(4))(2)SO(4), separated on SDS-PAGE and detected by Western blotting with homologous polyclonal anti/VTG antibody. Two lipovitellins of 110 and 116 kDa were always present in the yolk of laid eggs after 1, 10, 18, and 44 days from oviposition. Both these proteins were glycosylated and were recognized by the anti/VTG antibody; their N-terminal sequences were analyzed. Four phosvitins were detected in freshly laid eggs, but their number decreased during incubation, and after 44 days only a single protein of approximately 6.5 kDa was present. The results indicated that, in this lizard, during embryonic development, lipovitellins remain unchanged, whereas the phosphorylated components of yolk undergo continuous degradation.
Collapse
Affiliation(s)
- Maurizio Romano
- Department of Evolutionary and Comparative Biology, University Federico II, Via Mezzocannone, Napoli, Italy
| | | | | | | |
Collapse
|
29
|
Aubret F, Bonnet X, Shine R, Lourdais O. Fat is sexy for females but not males: the influence of body reserves on reproduction in snakes (Vipera aspis). Horm Behav 2002; 42:135-47. [PMID: 12367567 DOI: 10.1006/hbeh.2002.1793] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Reproduction is energetically expensive for both sexes, but the magnitude of expenditure and its relationship to reproductive success differ fundamentally between males and females. Males allocate relatively little to gamete production and, thus, can reproduce successfully with only minor energy investment. In contrast, females of many species experience high fecundity-independent costs of reproduction (such as migration to nesting sites), so they need to amass substantial energy reserves before initiating reproductive activity. Thus, we expect that the relationship between energy reserves and the intensity of reproductive behavior involves a threshold effect in females, but a gradual (or no) effect in males. We tested this prediction using captive vipers (Vipera aspis), dividing both males and females into groups of high versus low body condition. Snakes from each group were placed together and observed for reproductive behavior; sex-steroid levels were also measured. As predicted, females in below-average body condition had very low estradiol levels and did not show sexual receptivity, whereas males of all body condition indices had significant testosterone levels and displayed active courtship. Testosterone levels and courtship intensity increased gradually (i.e., no step function) with body condition in males, but high estradiol levels and sexual receptivity were seen only in females with body reserves above a critical threshold.
Collapse
Affiliation(s)
- Fabien Aubret
- Centre d'Etudes Biologiques de Chizé CNRS, 79360 Villiers en Bois, France
| | | | | | | |
Collapse
|
30
|
Limatola E, Manzo C, Manzo S, Monti MG, Rosanova P, Romano M. Oocyte growth and follicular hierarchy may be locally controlled by an inhibin-like protein in the lizard Podarcis sicula. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 2002; 292:96-102. [PMID: 11754026 DOI: 10.1002/jez.1146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The lizard Podarcis shows an ovarian annual cycle with three to four ovulatory waves between April and July (reproductive period). In August to September, a refractory stage occurs, followed by a nonreproductive period (October to March), during which the oocytes undergo slow growth and prepare themselves for vitellogenesis and ovulation. In the reproductive period, only a certain number of oocytes start growing, giving rise to a follicular hierarchy, which is controlled by still unknown mechanisms. In the present paper, immunoreactive inhibin was detected in previtellogenetic follicles of the reproductive period, and in particular, in the pyriform cells of the follicular epithelium. As the follicle grew and the pyriform cells disappeared, immunostaining shifted to the oocyte cytoplasm. The smaller follicles did not show any immunoreactivity. In the nonreproductive period, no follicles were labeled. We conclude that in the reproductive period, inhibin characterizes the follicles destined to ovulation and might be one of the main factors controlling follicular hierarchy.
Collapse
Affiliation(s)
- Ermelinda Limatola
- Department of Evolutionary and Comparative Biology, University of Naples "Federico II," 80134 Naples, Italy.
| | | | | | | | | | | |
Collapse
|
31
|
Mewes KR, Latz M, Golla H, Fischer A. Vitellogenin from female and estradiol-stimulated male river lampreys (Lampetra fluviatilis L.). THE JOURNAL OF EXPERIMENTAL ZOOLOGY 2002; 292:52-72. [PMID: 11754022 DOI: 10.1002/jez.1142] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The influence of estradiol-17beta (E(2)) on vitellogenesis is well documented for a number of oviparous craniates. We have examined the role that estradiol-17beta plays in the induction and regulation of vitellogenin synthesis in the maturing European river lamprey, Lampetra fluviatilis. In both females and males the estradiol-17beta concentrations in the plasma reached comparable maximum values in March, only a few weeks before spawning. Throughout the spawning run, the vitellogenin titer in the blood of females remains rather constant while the ovary volume increases. In contrast, we never found circulating VTG in untreated male lampreys. The synthesis and secretion of the yolk precursor molecule can be induced in males, however, by high doses of estradiol injected into the coelom. Lamprey vitellogenin was isolated from the blood of maturing females as well as from hormone-stimulated males and identified by its immunological and electrophoretic properties. In the blood plasma of both maturing female and estradiol-treated male lampreys it always appears simultaneously in two different molecular forms: a vitellogenin monomer with an apparent molecular weight of 310-330kDa and a dimer. After SDS treatment, vitellogenin is represented as a 212-kDa polypeptide.
Collapse
Affiliation(s)
- Karsten Rüdiger Mewes
- Abteilung Experimentelle Morphologie, Institut für Zoologie, Universität Mainz, D-55099 Mainz, Germany.
| | | | | | | |
Collapse
|
32
|
Radder RS, Shanbhag BA, Saidapur SK. Pattern of plasma sex steroid hormone levels during reproductive cycles of male and female tropical lizard, Calotes versicolor. Gen Comp Endocrinol 2001; 124:285-92. [PMID: 11742511 DOI: 10.1006/gcen.2001.7711] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Annual changes in gonadal activity and plasma sex steroid hormone levels in male and female Calotes versicolor [plasma testosterone (T) levels in males and 17 beta-estradiol (E(2)) and progesterone (P) levels in females] are described. In females both plasma E(2) (32.80 +/- 12.91 pg/ml) and P (1.72 +/- 0.79 ng/ml) levels are at their low levels during the postbreeding season when the gonads are regressed. With the onset of recruitment of vitellogenic follicles, E(2) levels begin to rise, reaching peak values (1306.00 +/- 407.01 pg/ml) when the follicles are preovulatory. During this time, plasma levels of P are low. Plasma E(2) levels decline (285.60 +/- 143.0 pg/ml) soon after ovulation, and circulating concentrations of P begin to rise, reaching peak value (19.24 +/- 10.03 ng/ml), during eggshell formation. In gravid females, at mid-gestation, the same pattern of E(2) secretion is found when a second set of follicles undergoes vitellogenesis. However, P levels remain low from mid-gestation (4.06 +/- 2.17 ng/ml) until oviposition. These findings suggest that high P levels are not needed for oviductal egg retention during late gestation and that low levels of P may facilitate growth of a new batch of vitellogenic follicles. In males, plasma levels of T are correlated with the spermatogenetic activity that accompanies breeding.
Collapse
Affiliation(s)
- R S Radder
- Department of Zoology, Karnatak University, Dharwad 580 003, India
| | | | | |
Collapse
|
33
|
Sica S, Fierro D, Iodice C, Muoio R, Filosa S, Motta CM. Control of oocyte recruitment: regulative role of follicle cells through the release of a diffusible factor. Mol Reprod Dev 2001; 58:444-50. [PMID: 11241782 DOI: 10.1002/1098-2795(20010401)58:4<444::aid-mrd13>3.0.co;2-n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To determine whether oogonial proliferation and oocyte recruitment are under control of hypophyseal and/or ovarian factors, we carried out a series of investigations using Podarcis sicula, a lizard inhabiting the temperate lowlands of Europe in which oocyte recruitment occurs throughout the year, as animal model. Germinal beds containing oogonia and oocytes in prefollicular stages were cocultured with different ovarian compartments in presence/absence of FSH, and the effects of different treatments were evaluated by counting the number of prelepto-leptotene oocytes. Results revealed that oocyte recruitment from the pool of oogonia is under the control of a factor released by follicle cells while FSH has an indirect effect on modulating oogonial proliferation. SDS-PAGE analyses carried out on media conditioned by follicles suggest that the factor involved in the control of oocyte recruitment may be a small protein (about 21 kDa) and that its release is dependent on the period of the ovarian cycle but apparently not on the circulating levels of FSH.
Collapse
Affiliation(s)
- S Sica
- Department of Evolutive and Comparative Biology, University of Naples, Federico II, Naples, Italy
| | | | | | | | | | | |
Collapse
|
34
|
Romano M, Limatola E. Oocyte plasma membrane proteins and the appearance of vitellogenin binding protein during oocyte growth in the lizard Podarcis sicula. Gen Comp Endocrinol 2000; 118:383-92. [PMID: 10843789 DOI: 10.1006/gcen.2000.7484] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the ovary of the lizard Podarcis sicula, the micropinocytotic uptake of the yolk exogenous precursor (i.e., vitellogenin; VTG) occurs only in the reproductive period and involves the plasma membrane of > or =2000-microm oocytes. This paper analyzes the intrinsic proteins extracted from the plasma membrane of growing oocytes to identify the vitellogenin binding protein during the different stages of the annual ovarian cycle of this species. Despite the well-known ultrastructural changes of the oocyte plasma membrane, SDS-PAGE failed to show marked variation in the total number of membrane proteins during the most significant stages of oocyte auxocytosis. Nevertheless, ligand blotting, using homologous VTG and anti-VTG, revealed that an congruent with115-kDa protein of the oocyte plasma membrane bound plasma vitellogenin only in the reproductive period (spring-summer) in both vitellogenic and nonvitellogenic oocytes. During the nonreproductive period, this molecule was never observed. However, it could be induced in the coldest months (winter) by hypophyseal gonadotropins.
Collapse
Affiliation(s)
- M Romano
- Department of Evolutionary and Comparative Biology, University of Naples "Federico II,", Italy
| | | |
Collapse
|
35
|
Amey AP, Whittier JM. Seasonal patterns of plasma steroid hormones in males and females of the bearded dragon lizard, Pogona barbata. Gen Comp Endocrinol 2000; 117:335-42. [PMID: 10764545 DOI: 10.1006/gcen.2000.7426] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pogona barbata is an Australian lizard that produces several large clutches of eggs between August and December (spring to early summer). Mating takes place around ovulation. The seasonal pattern of reproductive hormones in males and females of P. barbata was determined by radioimmunoassay of plasma progesterone (P), estradiol-17beta (E-17beta), corticosterone (B), and total androgen (TA). In females, P began to rise in August and was elevated from September to December. Corticosterone and TA were detectable but low and did not vary with time of year or reproductive condition. Estradiol-17beta was only detectable in a few females and exhibited no elevation with vitellogenic activity. These results suggest that B and TA are not involved in female reproduction. Estrogens may be either so low they could not be detected or they were present in a form other than estradiol-17beta. The high sensitivity of the estradiol-17beta radioimmunoassay suggests the latter. In males, TA peaked at the beginning of spring. They then declined to a minimum during November and December. However, concentrations recovered in the postbreeding activity period, January to April (summer and autumn). These patterns are consistent with the observation of maximum spermatogenic activity in spring, followed by the cessation of spermatogenesis directly after the breeding period and testicular recrudescence in February (late summer).
Collapse
Affiliation(s)
- A P Amey
- Department of Anatomical Sciences, The University of Queensland, Australia
| | | |
Collapse
|
36
|
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.
Collapse
Affiliation(s)
- S M Jones
- Department of Zoology, University of Tasmania, Hobart, TAS 7001, Australia
| | | | | |
Collapse
|
37
|
Sarkar S, Maiti BR, Sarkar NK. Seasonal pattern of ovarian growth and interrelated changes in plasma steroid levels, vitellogenesis, and oviductal function in the adult female soft-shelled turtleLissemys punctata punctata. CAN J ZOOL 1996. [DOI: 10.1139/z96-038] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The female reproductive cycle of the freshwater soft-shelled turtle Lissemys punctata punctata was studied by correlating ovarian growth with changes in plasma levels of steroids (17β-estradiol and progesterone), vitellogenic indices (calcium, lipid, protein, and cholesterol), and oviductal changes (growth, glycogen, and peroxidase levels). Ovarian growth starts after winter hibernation, proceeds slowly during the preparatory phase (March–June), becomes rapid in the recrudescent phase (July), and peaks in the breeding phase (August–September). Subsequently, the follicles undergo atresia in the regressive phase (October–November), which is followed by the quiescent phase (December–February) marked by negligible ovarian growth. Plasma levels of 17β-estradiol and vitellogenic indices reflect the same pattern of change as ovarian growth. The plasma progesterone concentration remains low throughout the reproductive cycle, except that the titre reaches a postovulatory peak and then declines prior to oviposition. Oviductal mass and glycogen and peroxidase concentrations correspond to changes in plasma estradiol concentration. The findings indicate that the seasonal reproductive cycle of L. p. punctata is characterized by a single annual peak of ovarian growth and estrogen secretion compared with a double peak recorded in other single-clutch turtles.
Collapse
|
38
|
Carnevali O, Sabbieti MG, Mosconi G, Polzonetti-Magni AM. Multihormonal control of vitellogenin mRNA expression in the liver of frog, Rana esculenta. Mol Cell Endocrinol 1995; 114:19-25. [PMID: 8674844 DOI: 10.1016/0303-7207(95)03637-m] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In Rana esculenta in an in vitro system, hepatic vitellogenin synthesis can be induced by growth hormone in both sexes. In this study: (1) the ability of this hormone to induce transcription of the VTG gene was determined, and (2) this ability was compared with that of estradiol-17 beta. The results indicate that growth hormone stimulates VTG mRNA transcription both in vivo and in vitro, in both sexes. The levels of mRNA are related to protein levels in the medium. In addition, seasonal variation occurs in the VTG gene transcription under growth hormone and estradiol-17 beta; indeed the more active inducer was growth hormone during the reproductive period and estradiol-17 beta during the preproductive phase.
Collapse
Affiliation(s)
- O Carnevali
- Department of Biology (MCA), University of Camerino, Italy
| | | | | | | |
Collapse
|
39
|
Gobbetti A, Zerani M, Bellini-Cardellini L, Bolelli GF. Prostaglandins and corticosterone in the oviparous female lizard, Podarcis sicula sicula, during reproduction. ACTA PHYSIOLOGICA SCANDINAVICA 1995; 153:301-8. [PMID: 7625183 DOI: 10.1111/j.1748-1716.1995.tb09866.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The in vitro effects of prostaglandin F2 alpha (PGF2 alpha) and prostaglandin E2 (PGE2) on corticosterone release by ovarian follicles, corpora lutea (CL), and interrenals were studied in the female lizard, Podarcis sicula sicula, during reproduction. Follicles and CL studied in the female lizard, Podarcis sicula sicula, during reproduction. Follicles and CL were divided according to their different developmental stages; follicles: previtellogenic, early-vitellogenic, mid-vitellogenic and fully-grown; CL: CL1 (unshelled eggs in the oviducts), CL2 (shelled eggs in the oviducts), CL3 (eggs laid 6 h previously) and CL4 (eggs laid 48 h previously). Interrenals were divided according to the reproductive stages: pre-vitellogenesis, vitellogenesis, ovulation, post-ovulation, and post-deposition. PGF2 alpha release was highest in fully-grown follicles and PGE2 in early-vitellogenic follicles, corticosterone was highest in pre-vitellogenic and lowest in early-vitellogenic follicles. PGE2 decreased corticosterone in pre-vitellogenic, mid-vitellogenic and fully-grown follicles. PGF2 alpha release was highest in CL4, and PGE2 in CL1 and CL2, corticosterone was highest in CL4. PGF2 alpha increased corticosterone in CL1, CL2 and CL3. In interrenals, PGF2 alpha release was highest and PGE2 lowest during ovulation, corticosterone was highest during ovulation. PGF2 alpha increased and PGE2 decreased interrenal corticosterone during vitellogenesis, ovulation, and post-ovulation. In the plasma, PGF2 alpha levels were highest and PGE2 lowest during ovulation, corticosterone was highest during ovulation. These results suggest that corticosterone, modulated by PGF2 alpha and PGE2, is implied in the reproductive processes with different roles. In fact this steroid could favour ovulatory and luteolytic processes. In addition the hypothesis of an anti-vitellogenic role of corticosterone is discussed.
Collapse
Affiliation(s)
- A Gobbetti
- Department of Molecular, Cellular and Animal Biology, University of Camerino, Italy
| | | | | | | |
Collapse
|
40
|
Carnevali O, Mosconi G, Yamamoto K, Kobayashi T, Kikuyama S, Polzonetti-Magni AM. Hormonal control of in vitro vitellogenin synthesis in Rana esculenta liver: effects of mammalian and amphibian growth hormone. Gen Comp Endocrinol 1992; 88:406-14. [PMID: 1490586 DOI: 10.1016/0016-6480(92)90235-c] [Citation(s) in RCA: 17] [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
Estradiol 17-beta is known to induce hepatic synthesis and secretion of vitellogenin in all species studied and in Rana esculenta, previous experiments demonstrated the involvement of pituitary in these processes; indeed, in addition to estradiol 17-beta, homologous pituitary homogenate directly stimulated male and female liver to produce vitellogenin in tissue cultures. Therefore, the effect of ovine growth hormone (o-GH) and Rana catesbeiana growth hormone (f-GH) on hepatic vitellogenin synthesis was investigated. In the present in vitro experiments, both o-GH and f-GH positively stimulated vitellogenin synthesis, in female and male liver, in a dose-related fashion. No significant differences were found in VTG levels induced by o-GH and f-GH. The GH stimulatory effects, found during the different phases of the reproductive cycle, displayed different trends related to season and sex.
Collapse
Affiliation(s)
- O Carnevali
- Department of Biology (MCA) University of Camerino, Italy
| | | | | | | | | | | |
Collapse
|
41
|
Carnevali O, Mosconi G. In vitro induction of vitellogenin synthesis in Rana esculenta: role of the pituitary. Gen Comp Endocrinol 1992; 86:352-8. [PMID: 1398001 DOI: 10.1016/0016-6480(92)90060-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Vitellogenin (VTG), a complex protein, is a precursor of yolk protein (lipovitellin and phosvitin) in all oviparous vertebrates studied to date. In amphibians, as in other oviparous vertebrates, VTG synthesis is hormonally dependent; estradiol-17 beta (E2) is especially important, although in vivo in the frog Rana esculenta the pituitary may be involved in hepatic VTG synthesis and secretion. The present in vitro experiments carried out during the main phases of the annual reproductive cycle of this frog showed that homologous pituitary homogenate (HPH), as well as E2, stimulated VTG synthesis in male and female livers, although their patterns of VTG secretion showed some differences with respect to the induction time and the rate of VTG secretion. The hepatic response to HPH occurred after a longer time than that of E2 VTG induction, and no cooperation between HPH and E2 was found in the VTG synthesizing response. It should be emphasized that during the refractory period (July), hepatic VTG synthesis in males and females could only be induced by HPH. These data demonstrate, for the first time, a direct action of HPH on VTG synthesis in male and female frog livers in all the periods tested; hepatic responsiveness to HPH and E2 varies with season and sex.
Collapse
Affiliation(s)
- O Carnevali
- Department of Biology (MCA) University of Camerino, Italy
| | | |
Collapse
|