title: Increased expression of Hsp70 and Hsp90 mRNA as biomarkers of thermal stress in loggerhead turtle embryos (Caretta Caretta).
abstract: The survival and viability of sea turtle embryos is dependent upon favourable nest temperatures throughout the incubation period. Consequently, future generations of sea turtles may be at risk from increasing nest temperatures due to climate change, but little is known about how embryos respond to heat stress. Heat shock genes are likely to be important in this process because they code for proteins that prevent cellular damage in response to environmental stressors. This study provides the first evidence of an expression response in the heat shock genes of embryos of loggerhead sea turtles (Caretta caretta) exposed to realistic and near-lethal temperatures (34°C and 36°C) for 1 or 3 hours. We investigated changes in Heat shock protein 60 (Hsp60), Hsp70, and Hsp90 mRNA in heart (n=24) and brain tissue (n=29) in response to heat stress. Under the most extreme treatment (36°C, 3h), Hsp70 increased mRNA expression by a factor of 38.8 in heart tissue and 15.7 in brain tissue, while Hsp90 mRNA expression increased by a factor of 98.3 in heart tissue and 14.7 in brain tissue. Hence, both Hsp70 and Hsp90 are useful biomarkers for assessing heat stress in the late-stage embryos of sea turtles. The method we developed can be used as a platform for future studies on variation in the thermotolerance response from the clutch to population scale, and can help us anticipate the resilience of reptile embryos to extreme heating events.
authors.affiliation: School of Animal Biology (M092), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; Oceans Institute (M470), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. Electronic address: jamie.tedeschi@research.uwa.edu.au.
authors.forename: J N
authors.initials: JN
authors.lastname: Tedeschi
authors.affiliation: School of Animal Biology (M092), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors.forename: W J
authors.initials: WJ
authors.lastname: Kennington
authors.affiliation: Commonwealth Scientific and Industrial Research Organisation (CSIRO), CSIRO Oceans and Atmosphere Flagship, PMB 5, Floreat, WA 6014, Australia.
authors.forename: O
authors.initials: O
authors.lastname: Berry
authors.affiliation: Marine Science Program, Department of Parks and Wildlife (DPaW), Locked Bag 104, Bentley Delivery Centre, WA, 6983, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Whiting
authors.affiliation: Oceans Institute (M470), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; Australian Institute of Marine Science (AIMS) (M096), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Meekan
authors.affiliation: School of Animal Biology (M092), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; Oceans Institute (M470), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors.forename: N J
authors.initials: NJ
authors.lastname: Mitchell
mesh_terms: D000818:Animals; D015415:Biomarkers; D001921:Brain / Q000378:metabolism; D018834:Chaperonin 60 / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response; D009206:Myocardium / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014426:Turtles / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D018834:Chaperonin 60; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D012333:RNA, Messenger
keywords: Biomarkers; Climate change; Gene expression; Heat stress; Hsp60, Hsp70, Hsp90; Sea turtles