栉孔扇贝免疫致敏（immune priming)现象及其机制的初步研究

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	栉孔扇贝免疫致敏（immune priming)现象及其机制的初步研究
其他题名	Preliminary study on immune priming and the related mechanism in Zhikong scallop Chlamys farreri
	丛明
学位类型	博士
	2008-06-10
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	栉孔扇贝免疫记忆免疫致敏免疫识别免疫反应死亡率
摘要	栉孔扇贝是我国重要的海水养殖品种，自1997年以来陆续爆发的大规模死亡，不仅造成了巨大的经济损失，而且直接威胁到现有产业的生存和发展。本研究通过比较扇贝在连续刺激条件下的不同免疫反应，推测栉孔扇贝中有无免疫致敏和记忆现象，观察短期免疫刺激对扇贝再次遇到相同病原物刺激时死亡率的影响，探讨栉孔扇贝的免疫致敏作用，并对其机制进行初步探讨，以期更好地了解扇贝的免疫防御机制，为扇贝病害防治提供参考。利用荧光实时定量PCR技术检测了扇贝受到鳗弧菌连续等量刺激后两种重要病原识别受体（PRR）基因的表达。结果显示，在受到连续两次刺激后CfPGRP-S1、LGBP基因的表达量均有不同程度的增加。其中CfPGRP-S1基因在受到第二次刺激后表达量增加的幅度高于第一次，且基因表达显著性增加的时间比第一次提前；LGBP基因在第二次刺激后，表达量显著性增加的时间也比第一次提前。同时，对同批处理的扇贝进行重要免疫指标的检测分析发现两次刺激后吞噬率变化不显著，而第二次刺激后吞噬指数的最大峰值高于第一次，并且最大峰值出现的时间比第一次提前；血淋巴中的抗菌活力和肝胰腺中SOD、MDA含量在两次刺激前后的变化不显著。在脊椎动物中，识别能力和抗菌能力的提高是免疫记忆的两个重要特点，栉孔扇贝在第二次免疫刺激后PRR识别能力的提高和吞噬作用的增强，说明扇贝中可能存在类似脊椎动物免疫记忆的免疫致敏作用。对扇贝进行两次鳗弧菌浸泡刺激，第一次为短期浸泡刺激，第二次为长期浸泡刺激。结果发现，第一次浸泡过的扇贝在遭受相同病原第二次刺激时，在一定时间段内其死亡率比未受第一次刺激的扇贝极显著降低，表明第一次的短期病原刺激增强了扇贝对第二次刺激的抵抗能力。同时比较第二次刺激过程中扇贝免疫指标的变化发现经过短期刺激扇贝的吞噬作用、ACP和AKP活性比未受过刺激的扇贝显著增强，而其他指标包括POL、SOD则差异不显著，说明增强的吞噬作用、ACP和AKP活性与扇贝的死亡率下降有关。研究结果表明栉孔扇贝中存在免疫致敏（immune priming）现象，短期刺激可以提高扇贝的免疫反应能力，增强扇贝机体对相同病原物的抵抗能力。
其他摘要	Zhikong scallop Chlamys farreri is an important cultured species in China and contributes enormously to the economic development of coastal provinces. Since the summer of 1997, large-scale mortalities have been causing catastrophic losses to scallop aquaculture. Investigation on scallop immune defense mechanism and searching for ways to enhance the disease resistance would be important to the disease control of scallop and the sustainable development of aquaculture in China. In this paper, comparisons between the immune responses after two sequential stimulations with the same amounts of Listonella anguillarum was performed in order to find out whether there was immunological memory in Zhikong scallops. To ascertain the previous immune experience has positive effect for the scallops to resist a secondary similar immune attack, the scallops were challenged twice by the same bacteria with same concentration, and cumulative mortality and several important immune parameters were recorded. This will help to better understand the internal defense mechanisms of scallop immunity and provide basic data for diseases prevention in shellfish aquaculture. Fluorescent real-time quantitative RT-PCR was used to examine the expression patterns of two important pathogen recognition receptors (PRRs) CfPGRP-S1 and LGBP in haemocytes of scallops after sequential challenges by Gram-negative bacteria L. anguillarum. Both genes were found up-regulated after the twice challenges and the up-regulation of CfPGRP-S1 after the secondary challenge was higher and earlier than that after the first challenge. The up-regulation of LGBP after the secondary challenge appeared earlier than that after the first challenge. It suggested that the pathogen recognition by the PRRs after the secondary challenge was enhanced and more rapidly responded than that after the previous challenge. Meanwhile, there was no significant difference in phagocytic rate (PR), antibacterial activity of hemolymph, SOD and MDA contents of hepatopancreas after the twice challenges, but the up-regulation of phagocytic index (PI) was higher and earlier after the secondary challenge than that after the first challenge. It suggested that phagocytes responded more powerfully and earlier after the secondary challenge than that after the first challenge.The enhanced pathogen recognition and the antibacterial resistance were known as two important characteristics of immunological memory in vertebrates. The enhanced recognition and phagocytosis after the secondary challenge suggested that it was possible for the scallops to have immune priming which was functionally similar to immunological memory in vertebrates. To ascertain immune priming in scallops, the scallops were challenged by a short and a long immersion in L. anguillarum solution. And the cumulative mortality of the scallops received a previous challenge was significant (P<0.01) lower than that of the control, implying that the first short-term immersion challenge endowed the scallops an enhanced resistance to the secondary challenge. Comparison of the immune parameters during the secondary challenge suggested that phagocytosis, ACP and AKP activity but not POL and SOD activities of the pre-challenged scallops were significantly higher than that of the non-challenged scallops. It implied that the enhanced phagocytosis and hydrolytic enzymes, such as ACP and AKP, were related to the enhanced immune resistance to the secondary immune challenge by L. anguillarum. All the results suggested that there was immune priming in the scallops and a short-term stimulation could give the scallops an enhanced immune ability to the secondary stimulation by the same pathogens.
页数	99
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/1385
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	丛明. 栉孔扇贝免疫致敏（immune priming)现象及其机制的初步研究[D]. 海洋研究所. 中国科学院海洋研究所,2008.

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