热应激奶牛外周血淋巴细胞凋亡和bax-α基因表达

Analysis of apoptosis and expression of bax-α of lymphocytes in peripheral blood of dairy cows

用流式细胞记录仪检测分析奶牛在夏季 (日平均气温为 37 5℃)、夏末 (日平均气温 26 5℃) 和冬季 (日平均气温 5 5℃) 时奶牛外周血淋巴细胞DNA含量, 统计细胞所处的分裂时期及淋巴细胞的凋亡率, 并通过荧光定量PCR分析上述时期外周血淋巴细胞bax α基因mRNA表达量。结果显示: (1) G2 /M期细胞和淋巴细胞增殖指数随温度降低而呈明显的下降趋势, 5 5℃时比例最低, 相对于其他两个温度条件差异显著 (P<0 05); (2) 淋巴细胞凋亡率于 26 5℃达到最高峰 (10 60% ), 5 5℃下降至最低 (2 7% ), 差异显著 (P<0 05); (3) 在 26 5℃, bax α基因mRNA表达量最高, 与其他两个温度条件相比该基因的丰度差异显著 (P<0 05); (4) bax α基因mRNA表达量与淋巴细胞凋亡率呈明显的平行关系。提示bax基因可能参与热应激引起的淋巴细胞凋亡过程。

The DNA content,cell phase and rate of apoptosis of lymphocytes in the peripheral blood of dairy cattle at different daily mean temperature were analysed by flow cytometry(FCM).The results were shown as follows:(1)The cell ratios at G 2/M phase and proliferation index(PI)at 5.5 ℃ were significantly different from the other two daily mean temperatures(P<0.05).They decreased accompanying with the decrease of daily mean temperature.(2)The rate of apoptosis of lymphocytes was 10.60% at 26.5 ℃,which was the highest among three groups.It was 2.70% at 5.5 ℃,which was the lowest compared with the other two groups(P<0.05).(3)The abundance of bax-α mRNA was analysed by RT-PCR.The expression level of bax-α was the highest at 26.5 ℃(P<0.05).(4)The bax-α mRNA expressions were paralleled to the ratios of apoptosis of lymphocytes.It is suggested that bax-α gene could participate in regulation of apoptosis of lymphocytes induced by heat stress.