Team:GZHS-United/Results
The Result
1.Experiment a
To find the difference of tolerance between zooxanthella APX and arabidopsis APX under three stress conditions: high temperature, strong illumination and different pH values. Firstly, we treat the protein samples respectively in different temperature gradients and measuring the activity of sample protein enzyme. Enzyme activity data of SymAPX3, SymAPX3-mut1, SymAPX3-mut2 and ATAPX1 were measured at room temperature, and the results were summarized as follows:
To find the difference of tolerance between zooxanthella APX and arabidopsis APX under illumination stress, we treat the protein samples respectively in different illumination intensity and measuring the activity of sample protein enzyme. The data of enzyme activities is showing below:
To find the difference of tolerance between zooxanthella APX and arabidopsis APX in different pH value, we treat the protein samples respectively in environment that have different pH values and measuring the activity of sample protein enzyme. The data of enzyme activities is showing below:
According to the line diagram, the enzyme activity of ATAPX1 is significantly higher than SymAPX3, SymAPX3-mut1 and SymAPX3-mut2 at all gradient temperatures, illumination intensity and pH values. It has a strong resistance to under three stress conditions: high temperature, strong illumination and pH value.
Therefore, we concluded that APX activity of arabidopsis has significant advantages in eliminating peroxides under various stress conditions especially high temperature, strong illumination and changing pH values.
2.Experiment b
To discover and compare the ways of increasing zooxanthellae APX enzyme activity, we further design experiment b. We mutated the predicted H2O2 binding on zooxanthellae APX enzyme directly and measure the enzyme activity of mutant proteins under three stress conditions: high temperature, strong illumination and different pH values. The data is shown below:
We found that the enzyme activity of the APX mutant of zooxanthellae was not significantly different from that of the wild type.
In addition, the activity of wild-type arabidopsis APX was significantly higher than that of zooxanthellae
From this, we come to two conclusions:
A. The predicted functional correlation between H2O2 binding site and SymAPX3 in the data cannot be determined at present
B. arabidopsis APX has the potential to replace zooxanthella APX and help zooxanthella remove peroxides
3.The Conclusion
To sum up, our project has completed the process of hypothesizing, designing experiments, processing and analyzing experimental data. There are three conclusions:
1.We compared the enzyme activity between zooxanthellae APX and arabidopsis APX at different temperatures. We believe that arabidopsis APX have high potential of replacing zooxanthellae APX and helping algae remove peroxides.
2. While the enzyme activity of zooxanthelae apx after mutating the H2O2 binding site is nearly the same as before, we concluded that it is more difficult to rise the apx enzyme activity by changing the genes of zooxanthellae itself than by directly transplanting the genes related to higher plants
3. We expected to verify the functional site hypothesis from the biological experiment level. The experimental results partially indicated that there were doubts about the H2O2 binding site predicted by bioinformatics methods, at least in terms of functional correlation.
We hope that our project can contributed to further study of coral bleaching. For example, for teams that developed zooxanthella transformation system, they can choose to transform our "pET28b rplJ - ATAPX1" parts into zooxanthella and observe the reaction of zooxanthella - coral symbionts under high temperature stress. We hope that our research will help to improve the heat resistance of the zooxanthella-coral symbionts corals and help the coral to regain their color.