The Response Of Heat Shock Proteins To Acute Heat Stress In The Embryos Of Reptiles And Birds

As one of the most important ecological factors, temperature could affect the abundance,distribution and life activities of species. Studying the response to temperature variations are of great significance both theoretically and practically in the context of global warming.Most reptiles and birds are oviparous amniotes, embryos of which are exposed to the environmental temperature during development. Thus temperature variation could induce more serious impact on embryos than adults in these species. Heat shock proteins (HSFs) play an important role in acute heat shock response of animals. We raise following questions:(1) Do difference of heat shock response profile exist between reptiles embryos and birds embryos? (2) Whether heat shock protein from different families response to the same temperature differently? To answer these questions, we choose Mongolia Racerunner (Eremias argus), soft-shelled turtle (Pelodiscus sinensis), quail(Coturnix coturnix) and Beijing Duck (Anas platyrhynchos) embryos as experimental subjects in this research. The eggs were exposed to a series of temperatures, from 24 °C to 49 ℃,while the lethal temperature of embryos were recorded. We chose six heat shock proteins, i.e. Hsp27, Hsp40, Hsp60, Hsp90a, Hsp90β and Hsp105 for real-time fluorescence quantitative (Quantitative Real-time PCR) research. Then, detected the difference on transcription level.The results showed that:the lethal temperature of reptilian embryo (Mongolia Racerunner and soft-shelled turtle) was 49 °C; The lethal temperature of quail was 49 °C, while lethal temperature of Beijing duck was 47 °C. In lizard embryo, the expression of Hsp27, Hsp40, Hsp60, Hsp90a, Hsp90β and Hsp105 was significantly induced under acute temperature stress; In soft-shelled turtle embryos, the expression of Hsp40, Hsp60, Hsp90a and Hsp105 was significantly induced under acute temperature stress; In quail embryos, the expression of Hsp27, Hsp40, Hsp60, Hsp90a and Hsp105 was significantly induced under acute temperature stress; In Beijing duck embryos, the expression of Hsp27, Hsp40, Hsp60, Hsp90a, Hsp90β and Hsp105 was significantly induced under acute temperature stress. Meanwhile, six heat shock proteins exhibited very different responses to temperature stress. Hsp90a and Hsp105 in four species were highly expressed when being exposed to temperature stress. Hsp90a increased about 20-fold to 60 -fold, and Hsp105 increased about 20-fold to 200-fold. In addition, Hsp60 was upregulated in lizard and Beijing duck, and Hsp27 was significantly higher in Beijing Duck. Further, different genes had different Ton and Tmax·It’s obvious that the Ton of birds was generally about 2-4°C higher than that of reptiles in the comparison of four species.Therefore, when the embryos of reptiles and birds are exposed to acute heat shock, Hsp90a and Hsp105 are major molecular chaperones. Both of them assist organism to maintain intracellular homeostasis and protect cell from heat damage.