【科学60秒】酷暑之下，疫苗也被热死了_英语听力练习mp3下载-科学-沪江听力酷

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【科学60秒】酷暑之下，疫苗也被热死了

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Some bacteria have adapted to super cold environments for millions of years. And scientists have isolated some of the essential genes that allow bacteria to tolerate their harsh living conditions—because these same genes might help in the creation of new vaccines. The investigators published their findings in the Proceedings of the National Academy of Sciences.
Researchers from the University of Victoria in British Columbia isolated temperature-sensitive genes from some bacteria that thrive in the ___1___. They inserted nine of these cold-loving genes into a bacterial pathogen called Francisella tularensis. At about room temperature, the cells propagated. But when they had to cope with warmth equivalent to the ___2___ body temps of mammals, the bacteria died.
So the scientists injected these ___3___ pathogens into rats and mice at cool parts of the body, such as the ___4___ regions of the ear and the base of the tail. The bacteria survived near the skin, but perished ___5___ reaching the internal organs. And before they expired, the bacteria generated a protective immune response in the animals. The scientists hope to use this tool to create live vaccines that will confer immunity—before they die from our too warm welcome.