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Cobham AE, Rohner N. Unraveling stress resilience: Insights from adaptations to extreme environments by Astyanax mexicanus cavefish. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2024; 342:178-188. [PMID: 38247307 DOI: 10.1002/jez.b.23238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 12/26/2023] [Accepted: 01/02/2024] [Indexed: 01/23/2024]
Abstract
Extreme environmental conditions have profound impacts on shaping the evolutionary trajectory of organisms. Exposure to these conditions elicits stress responses, that can trigger phenotypic changes in novel directions. The Mexican Tetra, Astyanax mexicanus, is an excellent model for understanding evolutionary mechanisms in response to extreme or new environments. This fish species consists of two morphs; the classical surface-dwelling fish and the blind cave-dwellers that inhabit dark and biodiversity-reduced ecosystems. In this review, we explore the specific stressors present in cave environments and examine the diverse adaptive strategies employed by cave populations to not only survive but thrive as successful colonizers. By analyzing the evolutionary responses of A. mexicanus, we gain valuable insights into the genetic, physiological, and behavioral adaptations that enable organisms to flourish under challenging environmental conditions.
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Affiliation(s)
- Ansa E Cobham
- Stowers Institute for Medical Research, Missouri, Kansas City, USA
| | - Nicolas Rohner
- Stowers Institute for Medical Research, Missouri, Kansas City, USA
- Department of Cell Biology & Physiology, University of Kansas Medical Center, Kansas City, Missouri, USA
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Williamson SA, Hoover AL, Evans RG, Shillinger GL, Bailey H, Bruno RS, Bandimere A, Reina RD. Effects of postovipositional hypoxia and hyperoxia on leatherback turtle reproductive success and hatchling performance. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2023; 339:939-950. [PMID: 37545193 DOI: 10.1002/jez.2743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/27/2023] [Accepted: 07/28/2023] [Indexed: 08/08/2023]
Abstract
Leatherback egg clutches typically experience lower hatching success (~50%) than those of other sea turtle species (>70%). The majority of embryonic death (>50%) occurs at early stages of development, possibly because embryos fail to break preovipositional embryonic arrest after oviposition. The embryonic arrest is maintained by hypoxia in the oviduct and following oviposition increased availability of oxygen is the trigger that breaks arrest in all turtle species studied to date. We conducted an ex situ incubator experiment and an in situ hatchery experiment to examine the influence of oxygen availability on hatching success and hatchling traits in leatherbacks. After oviposition, eggs (n = 1005) were incubated in either normoxia (21% O2 ), hyperoxia (32%-42% O2 ) for 5 days, or hypoxia (1% O2 ) for 3 or 5 days. As with other turtles, hypoxic incubation maintained embryos in arrest, equivalent to the time spent in hypoxia. However, extending arrest for 5 days resulted in greater early-stage death and a significant decrease in hatching success (4% 5-day hypoxia vs. 72% normoxia). Eggs placed in incubators had greater hatching success than those placed into hatchery nests (67% vs. 47%, respectively). We found no impact of hyperoxia on the stage of embryonic death, hatching success, hatchling phenotype, exercise performance, or early dispersal. Our findings indicate that delayed nesting and the subsequent extension of embryonic arrest may negatively impact embryonic development and therefore the reproductive success of leatherbacks. They also indicate that incubation under hyperoxic conditions is unlikely to be a useful method to improve hatching success in this species.
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Affiliation(s)
- Sean A Williamson
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Aimee L Hoover
- Upwell, Monterey, California, USA
- Chesapeake Biological Laboratory, University of Maryland Centre for Environmental Science, Solomons, Maryland, USA
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, Australia
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | | | - Helen Bailey
- Chesapeake Biological Laboratory, University of Maryland Centre for Environmental Science, Solomons, Maryland, USA
| | - Renato Saragoça Bruno
- Turtle Love, Barra de Parismina, Limon, Costa Rica
- Pacuare Reserve, Ecology Project International, Limon, Costa Rica
| | | | - Richard D Reina
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
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Liu N, Zhang P, Xue M, Xiao Z, Zhang M, Meng Y, Fan Y, Qiu J, Zhang Q, Zhou Y. Variations in the Intestinal Microbiota of the Chinese Soft-Shelled Turtle ( Trionyx sinensis) between Greenhouse and Pond Aquaculture. Animals (Basel) 2023; 13:2971. [PMID: 37760371 PMCID: PMC10525211 DOI: 10.3390/ani13182971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/13/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
The microbial community structure in aquaculture water plays an important role in the intestinal microbial diversity of aquatic animals. The Chinese soft-shelled turtle (SST) (Trionyx sinensis) is an important aquaculture species of high economic value in the Asia-Pacific region. An intuitive understanding of the microbial diversity and abundances of SST aquaculture is crucial for comprehending these ecosystems. Herein, the evolutionary characteristics of the bacterial communities in the SST and its aquaculture water systems were investigated using Illumina MiSeq sequencing. This experiment sampled nine SSTs from a pond outside a greenhouse and was repeated three times. The sequencing results revealed significant differences in the microflora composition at the phylum and genus levels in both the intestine and aquaculture water of the SSTs in the greenhouse and pond aquaculture environments. A total of 1039 genera belonging to 65 phyla were identified. At the phylum level, the relative abundances of Chloroflexi (24%), Acidobacteria (5%), and Nitrospira (3%) were higher in the greenhouse water than in the pond water. The relative abundances of Bacteroidetes (35%), Actinobacteria (8%), and Cyanobacteria (4%) were higher in the pond water than in the greenhouse water. The intestinal microorganisms in the SSTs experienced significant changes after the SSTs were transferred from a greenhouse culture to a pond culture environment for 28 days. After the SSTs were cultured in the ponds, we observed decreases in the relative abundances of Actinobacteria (39% to 25%), Cyanobacteria (24% to 0.8%), Chlorobacteria (9% to 3%), and Firmicutes (5.5% to 0.8%. However, we observed increases in the relative abundances of Bacteroidetes (2% to 35%) and Acidobacteria (0.3% to 25%). These results showed that the bacterial diversity and richness compositions in the intestinal tract and aquaculture water were the same. However, the relative abundances of bacterial communities varied. The results of this study are of great significance in understanding how the environment affects SST cultures. These data may provide valuable instructions for Chinese soft-shelled turtle aquaculture management.
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Affiliation(s)
- Naicheng Liu
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; (N.L.); (P.Z.); (M.X.); (Z.X.); (M.Z.); (Y.M.); (Y.F.)
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China;
- National Pathogen Collection Center for Aquatic Animals, Shanghai Ocean University, Shanghai 201306, China
| | - Peng Zhang
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; (N.L.); (P.Z.); (M.X.); (Z.X.); (M.Z.); (Y.M.); (Y.F.)
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China;
- National Pathogen Collection Center for Aquatic Animals, Shanghai Ocean University, Shanghai 201306, China
| | - Mingyang Xue
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; (N.L.); (P.Z.); (M.X.); (Z.X.); (M.Z.); (Y.M.); (Y.F.)
| | - Zidong Xiao
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; (N.L.); (P.Z.); (M.X.); (Z.X.); (M.Z.); (Y.M.); (Y.F.)
| | - Mengjie Zhang
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; (N.L.); (P.Z.); (M.X.); (Z.X.); (M.Z.); (Y.M.); (Y.F.)
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China;
- National Pathogen Collection Center for Aquatic Animals, Shanghai Ocean University, Shanghai 201306, China
| | - Yan Meng
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; (N.L.); (P.Z.); (M.X.); (Z.X.); (M.Z.); (Y.M.); (Y.F.)
| | - Yuding Fan
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; (N.L.); (P.Z.); (M.X.); (Z.X.); (M.Z.); (Y.M.); (Y.F.)
| | - Junqiang Qiu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China;
- National Pathogen Collection Center for Aquatic Animals, Shanghai Ocean University, Shanghai 201306, China
| | - Qinghua Zhang
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China;
- National Pathogen Collection Center for Aquatic Animals, Shanghai Ocean University, Shanghai 201306, China
| | - Yong Zhou
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; (N.L.); (P.Z.); (M.X.); (Z.X.); (M.Z.); (Y.M.); (Y.F.)
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Adams DM, Williamson SA, Evans RG, Reina RD. Increasing hypoxia progressively slows early embryonic development in an oviparous reptile, the green turtle, Chelonia mydas. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220709. [PMID: 36061518 PMCID: PMC9428527 DOI: 10.1098/rsos.220709] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023]
Abstract
Green turtle (Chelonia mydas) embryos are in an arrested state of development when the eggs are laid, but in the presence of oxygen, arrest is broken and development resumes within 12-16 h. However, the precise oxygen level at which embryos break arrest and continue development is not known. To better understand the impact of oxygen concentration on breaking of arrest and early embryonic development, we incubated freshly laid eggs of the green sea turtle for three days at each of six different oxygen concentrations (less than or equal to 1%, 3%, 5%, 7%, 9% and 21%) and monitored the appearance and growth of white spots on the shell, indicative of embryonic development. As reported previously, white spots did not develop on eggs incubated in anoxia (less than or equal to 1% oxygen). For all other treatments, mean time to white spot detection and white spot growth rate varied inversely with oxygen concentration. In nearly all cases the difference between eggs at different oxygen levels was statistically significant (p ≤ 0.05). This suggests that sea turtle embryonic development may respond to oxygen in a dose-dependent manner. Our results indicate that the development of green turtle embryos may be slowed if they are exposed to the most hypoxic conditions reported in mature natural nests.
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Affiliation(s)
| | | | - Roger G. Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria 3010, Australia
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