Comparison of gene expression in whole blood of mice subjected to hypobaric hypoxia at Mt. Everest in vivo.

To determine hypoxia mediated changes in whole blood, normal swiss webster mice were gradually exposed to a chronic hypobaric hypoxic environment up to 8500m, for 2 weeks in vivo. Control, age-matched mice were maintained under normoxic conditions in Kathmandu (c. 1300 mts above sea level). Purpose: To examine and characterize the expression profile of genes expressed at hypobaric hypoxia on Mt. Everest of whole blood in comparison to the control. Methods: At the beginning of the experiment mice were divided into two groups, control (room condition, Kathmandu, Nepal) and hypoxic (hypoxic condition). For conditioning, the hypoxic group was exposed to lower levels of hypobaric hypoxia during our mountaineering expedition to Mt Everest. The oxygen level was decreased according to our climbing protocol from 21% to about 7% over a period of 15 days. Food and water were changed daily during the course of the experiment. After 15 days animals were euthanized after whole blood extraction from V. Cava for further analysis. RNA from whole blood was isolated, processed and used for microarray-based expression profiling. Profiles were generated for genes differentially expressed at control versus hypobaric hypoxia in whole blood using a false discovery rate (FDR) of 0%.We validated the profiles by real-time quantitative reverse transcription-polymerase chain reaction (qPCR). Results: The regional transcriptomes associated with hypobaric hypoxia on Mt. Everest in whole blood were identified. We found 947 genes that were differentially expressed in normobaric hypoxic whole blood compared to control with a 0% FDR and a 2 fold cutoff. Conclusion: Transcriptome level differences exist between control and hypobaric hypoxia in whole blood. Our definition of the synaptic transcriptome provides insight into the functioning of the unique response to hypoxia in whole blood.

为探究低氧介导的全血转录组变化，将正常瑞士韦伯斯特（Swiss Webster）小鼠在体内逐步暴露于模拟海拔8500米的慢性低压低氧环境，持续2周。年龄匹配的对照组小鼠则饲养于尼泊尔加德满都（海拔约1300米）的常氧环境中。

研究目的：本研究旨在对比对照组与模拟珠穆朗玛峰低压低氧环境下的全血基因表达谱，并对其进行系统表征分析。

实验方法：实验伊始，将小鼠分为两组：对照组（饲养于尼泊尔加德满都的常氧室内环境）与低氧暴露组。在本次珠穆朗玛峰登山科考过程中，对低氧暴露组小鼠进行渐进式低压低氧适应训练：按照本次登山实验方案，在15天内将吸入氧浓度从21%逐步降至约7%。实验期间每日更换饲料与饮水。15天后，通过腔静脉采集全血后对小鼠实施安乐死，采集的全血用于后续实验分析。提取全血中的总RNA，经纯化处理后用于基于基因芯片（microarray）的表达谱分析。以错误发现率（false discovery rate, FDR）为0%作为筛选阈值，构建对照组与低压低氧暴露组全血中差异表达基因的表达谱。随后通过实时定量反转录聚合酶链反应（real-time quantitative reverse transcription-polymerase chain reaction, qPCR）对表达谱结果进行验证。

实验结果：本研究成功鉴定出与珠穆朗玛峰低压低氧环境相关的全血区域转录组。以0%错误发现率及2倍表达变化倍数为筛选阈值，我们发现相较于对照组，低压低氧暴露组的全血中共存在947个差异表达基因。

研究结论：对照组与低压低氧暴露组的全血转录组水平存在显著差异。我们对突触转录组的界定，为解析全血对低氧的独特应答机制提供了全新的认知视角。