以泥蚶为模型的滩涂贝类镉解毒功能研究

Cadmium is one of the most toxic heavy metals. The concentration reaching to 0.001mg/L can be toxic. Bivalves have strong ability in accumulating heavy metals, so the safety problem as food is more and more concerned. Among the interdial bivalves, Tegillarca granosa accumulated more cadmium than others, and they are still survival. Furthermore, from the morphology of the organs, there are no pathological changes. Thus, basing on RNA-seq technology, Tegillarca granosa will be used as model, and its gill transcriptome library, DGE libraries will be conducted under Cd, Cu,Cd+Cu stress,in order to reveal the selective accumulation mechanism of Cd. Meanwhile the visceral mass transcriptom library and DGE libraries will be conducted under Cd stress, following to screen the differential expression genes, so as to investigate the detoxification mechanism of Cd. Then using the protein purification technology and High performance liquid chromatography, the chelation protein of Cd will be purified and identified.The selective accumulation and detoxification mechanism of Cd in Tegillarca granosa would be clarified combined with both the transcriptom level and protein level. Through our study, the theoretical guarantee would be provided for the construction and spreading of the low cadmium strain in future,and the regulation mechanism of the interdial bivalves would be well understood and enriched.

Cd为毒性最强的重金属之一，其浓度仅达到0.001mg/L便可产生毒性作用。贝类具有高的重金属累积能力，其食品安全问题也越来越多地受到公众关注。在滩涂贝类中泥蚶较其他种类能累积更多的重金属Cd，且能存活、没有出现组织畸变。因此，本项目以泥蚶为模型，基于RNA-seq技术，构建Cu、Cd、Cu+Cd应激下泥蚶鳃的转录组文库及数字基因表达谱（DGE）文库，解析泥蚶选择性富集Cd的分子机制；同时构建Cd胁迫后泥蚶内脏团转录组文库及DGE文库，分析其内脏团的基因表达差异情况，筛选差异表达功能基因及代谢通路，初步探讨其对重金属Cd的调控网络及高能力解毒机制；在蛋白水平上，利用蛋白纯化技术和色谱技术，提纯并鉴定重金属Cd螯合蛋白，与转录组水平相结合来进一步探讨泥蚶对重金属Cd的选择性富集机制及解毒机制，为后续快速构建和推广泥蚶“低镉品系”提供理论保障，有助于更好地理解和丰富滩涂贝类对重金属的调控机理。

Cd为毒性最强的重金属之一，其浓度仅达到0.001mg/L便可产生毒性作用。贝类具有高的重金属累积能力，其食品安全问题也越来越多地受到公众关注。在滩涂贝类中泥蚶较其他种类能累积更多的重金属Cd，且能存活、没有出现组织畸变。因此本项目以泥蚶为模型，结合泥蚶基因组，利用高通量测序技术，构建并比较分析Cd、Cu、Cd＆Cu胁迫下泥蚶鳃转录组文库，利用GO富集及KEGG富集法，筛查泥蚶选择性富集Cd的重要调控通路及关键基因，并对其关键基因进行重金属胁迫后的响应表达研究，解析泥蚶选择性富集Cd的分子机理；同时亦构建和比较分析Cd胁迫后泥蚶内脏团转录组文库，筛选泥蚶对Cd耐受的重要调控通路及关键基因，并对其进行Cd胁迫后的表达模式研究，探讨其对Cd的调控网络及解毒机制。项目实施3年来，取得了一系列重要成果：（1）筛查得到泥蚶选择性富集Cd的关键通路及关键基因，证实Cd2+是通过离子通道进入细胞，并经内吞作用后由泛素化介导，转运至溶酶体内，实现其在机体内的转运、储存及解毒作用；（2）筛选出了泥蚶Cd耐受关键调控通路（“免疫系统”、“信号转导”、“信号分子与相互作用”）及Cd耐受关键基因[泥蚶溶酶体半胱氨酸蛋白酶L、F（CTSL、CTSF）、金属蛋白酶（MEP1B）、泛素结合酶（UBE2F）]，表明溶酶体是泥蚶对Cd解毒的主要方式，其半胱氨酸蛋白酶（CTSL、CTSF）对储存与此的Cd进行解毒。