1
|
Kohno S. Can Xenobiotics Alter the Sex Ratio of Crocodilians in the Wild? Sex Dev 2021; 15:179-186. [PMID: 34161954 DOI: 10.1159/000515724] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 03/07/2021] [Indexed: 11/19/2022] Open
Abstract
All crocodilians exhibit temperature-dependent sex determination without sex chromosomes. This temperature dependency can be overridden by exposure to estrogen via estrogen receptor 1. Thus, the sex ratio of crocodilian species is vulnerable to estrogenic xenobiotics. Multiple investigations of the mechanism and effects of xenobiotics in crocodilian species have been conducted since the early 1990s. This review focuses on the impact of xenobiotics on sex determination rather than gonadal functions in crocodilians. The thermosensitive and estrogen-sensitive periods that commit the bipotential gonad to develop as an ovary end by stages 24.5 and 25.3, respectively. In contrast, it is ambiguous when the estrogen-sensitive stage begins for ovarian development, although the thermosensitive period for ovarian development initiates around developmental stage 15 at an extreme female-producing temperature of 30°C. To accurately assess the effect of xenoestrogens on sex ratio in crocodilians, it is critical to collect eggs before the sex-determining period and to incubate them under precisely controlled temperatures. A well-studied system of xenobiotic effects on crocodilians is Lake Apopka (FL, USA), an EPA superfund clean-up site heavily contaminated with Dieldrin, Endrin, and p,p'-DDE. The sum of estimated estrogenicity of xenobiotics measured in Lake Apopka was insufficient to activate the estrogen receptor 1 of Alligator mississippiensis, which is an essential receptor to induce ovarian development. Although juvenile A. mississippiensis showed gonadal alterations in sex hormone production and histology, the environmentally relevant concentration of xenobiotics in Lake Apopka was unlikely to alter the sex ratio of A. mississippiensis. Experimental exposure to xenobiotics such as 17α-ethynylestradiol, p,p'-dichlorodiphenyldichloroethylene, and 2,3,7,8-tetrachlorodibenzodioxin at environmentally relevant concentrations in ovo induced more female offspring in A. mississippiensis as compared with the control group. Bisphenol-A, atrazine, 2,4-dichlorophenoxyacetic acid, endosulfan, and Corexit did not alter the sex ratio of A. mississippiensis or Caiman latirostris under the tested conditions. Egg-incubation temperature has pronounced effects on estrogen sensitivity in crocodilian sex determination. Therefore, crocodilians are vulnerable to xenobiotic contamination and climate change in the wild. It is vital to further investigate the detailed mechanism and effects of environmental xenobiotics in crocodilian sex determination to mitigate their effect on sex ratio and conserve this ancient lineage.
Collapse
Affiliation(s)
- Satomi Kohno
- Aquatic Toxicology Laboratory, Department of Biological Sciences, Saint Cloud State University, St. Cloud, Minnesota, USA
| |
Collapse
|
2
|
Nagahama Y, Chakraborty T, Paul-Prasanth B, Ohta K, Nakamura M. Sex determination, gonadal sex differentiation, and plasticity in vertebrate species. Physiol Rev 2020; 101:1237-1308. [PMID: 33180655 DOI: 10.1152/physrev.00044.2019] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A diverse array of sex determination (SD) mechanisms, encompassing environmental to genetic, have been found to exist among vertebrates, covering a spectrum from fixed SD mechanisms (mammals) to functional sex change in fishes (sequential hermaphroditic fishes). A major landmark in vertebrate SD was the discovery of the SRY gene in 1990. Since that time, many attempts to clone an SRY ortholog from nonmammalian vertebrates remained unsuccessful, until 2002, when DMY/dmrt1by was discovered as the SD gene of a small fish, medaka. Surprisingly, however, DMY/dmrt1by was found in only 2 species among more than 20 species of medaka, suggesting a large diversity of SD genes among vertebrates. Considerable progress has been made over the last 3 decades, such that it is now possible to formulate reasonable paradigms of how SD and gonadal sex differentiation may work in some model vertebrate species. This review outlines our current understanding of vertebrate SD and gonadal sex differentiation, with a focus on the molecular and cellular mechanisms involved. An impressive number of genes and factors have been discovered that play important roles in testicular and ovarian differentiation. An antagonism between the male and female pathway genes exists in gonads during both sex differentiation and, surprisingly, even as adults, suggesting that, in addition to sex-changing fishes, gonochoristic vertebrates including mice maintain some degree of gonadal sexual plasticity into adulthood. Importantly, a review of various SD mechanisms among vertebrates suggests that this is the ideal biological event that can make us understand the evolutionary conundrums underlying speciation and species diversity.
Collapse
Affiliation(s)
- Yoshitaka Nagahama
- Laboratory of Reproductive Biology, National Institute for Basic Biology, Okazaki, Japan.,South Ehime Fisheries Research Center, Ehime University, Ainan, Japan.,Faculty of Biological Science and Technology, Kanazawa University, Ishikawa, Japan
| | - Tapas Chakraborty
- Laboratory of Reproductive Biology, National Institute for Basic Biology, Okazaki, Japan.,South Ehime Fisheries Research Center, Ehime University, Ainan, Japan.,Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukouka, Japan.,Karatsu Satellite of Aqua-Bioresource Innovation Center, Kyushu University, Karatsu, Japan
| | - Bindhu Paul-Prasanth
- Laboratory of Reproductive Biology, National Institute for Basic Biology, Okazaki, Japan.,Centre for Nanosciences and Molecular Medicine, Amrita Vishwa Vidapeetham, Kochi, Kerala, India
| | - Kohei Ohta
- Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukouka, Japan
| | - Masaru Nakamura
- Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Okinawa, Japan.,Research Center, Okinawa Churashima Foundation, Okinawa, Japan
| |
Collapse
|
3
|
Eklund RL, Knapp LC, Sandifer PA, Colwell RC. Oil Spills and Human Health: Contributions of the Gulf of Mexico Research Initiative. GEOHEALTH 2019; 3:391-406. [PMID: 32159026 PMCID: PMC7038885 DOI: 10.1029/2019gh000217] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 10/04/2019] [Accepted: 10/12/2019] [Indexed: 05/23/2023]
Abstract
The Gulf of Mexico Research Initiative (GoMRI) was established in 2010 with $500 million in funding provided by British Petroleum over a 10-year period to support research on the impacts of the Deepwater Horizon oil spill and recovery. Contributions of the GoMRI program to date focused on human health are presented in more than 32 peer-reviewed papers published between 2011 and May 2019. Primary findings from review of these papers are (i) the large quantity of dispersants used in the oil cleanup have been associated with human health concerns, including through obesogenicity, toxicity, and illnesses from aerosolization of the agents; (ii) oil contamination has been associated with potential for increases in harmful algal blooms and numbers of pathogenic Vibrio bacteria in oil-impacted waters; and (iii) members of Gulf communities who are heavily reliant upon natural resources for their livelihoods were found to be vulnerable to high levels of life disruptions and institutional distrust. Positive correlations include a finding that a high level of community attachment was beneficial for recovery. Actions taken to improve disaster response and reduce stress-associated health effects could lessen negative impacts of similar disasters in the future. Furthermore, GoMRI has supported annual conferences beginning in 2013 at which informative human health-related presentations have been made. Based on this review, it is recommended that the Oil Pollution Act of 1990 be updated to include enhanced funding for oil spill impacts to human health.
Collapse
Affiliation(s)
- Ruth L. Eklund
- Masters in Environmental and Sustainability Studies ProgramCollege of CharlestonCharlestonSCUSA
| | - Landon C. Knapp
- Center for Coastal Environmental and Human HealthCollege of CharlestonCharlestonSCUSA
| | - Paul A. Sandifer
- Center for Coastal Environmental and Human HealthCollege of CharlestonCharlestonSCUSA
| | - Rita C. Colwell
- University of MarylandMDUSA
- School of Public HealthJohns Hopkins UniversityBaltimoreMDUSA
| |
Collapse
|
4
|
McCoy KA, Amato CM, Guillette LJ, St Mary CM. Giant toads (Rhinella marina) living in agricultural areas have altered spermatogenesis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 609:1230-1237. [PMID: 28787797 PMCID: PMC5600858 DOI: 10.1016/j.scitotenv.2017.07.185] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 07/19/2017] [Accepted: 07/21/2017] [Indexed: 06/07/2023]
Abstract
Across diverse taxa, germ cell development is controlled by an intricate cascade of processes that are tightly controlled by the hypothalamic-pituitary-gonadal axis. Endocrine disturbances, such as those induced by endocrine disrupting chemicals (EDCs) can negatively affect spermatogenesis. Here, we investigate whether spermatogenesis is altered in the giant toad, Rhinella marina, living in agricultural areas where EDCs are used relative to suburban areas. We also ask if reductions in spermatogenesis were associated with developmental gonadal abnormalities (intersex) found in the same frogs. We found that toads in agricultural areas exhibited reduced spermatogenesis relative to non-agricultural animals, and that those reductions were not associated with gross gonadal abnormalities. All toads living in agricultural areas had reduced spermatogenesis relative to those living in non-agricultural areas regardless of whether they had gonadal abnormalities originating during development. Similarities in reproductive dysfunction among diverse taxa living in agricultural areas, including humans, suggest that many vertebrate taxa living in agricultural areas around the globe are likely experiencing some level of reproductive dysfunction.
Collapse
Affiliation(s)
- Krista A McCoy
- Department of Biology, East Carolina University, Greenville, NC 27858, USA.
| | - Ciro M Amato
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
| | - Louis J Guillette
- Department of Obstetrics and Gynecology (L.J.G.), Medical University of South Carolina, and Hollings Marine Laboratory, Charleston, SC 29425, USA
| | - Colette M St Mary
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| |
Collapse
|