栉孔扇贝不同组织中镉的微区分布特征及其变化规律

Research on the subcellular fate and transformation of cadmium in different tissues of the scallop Chlamys farreri

摘要:

为阐明扇贝特异性富集镉（Cd）的机理，研究了栉孔扇贝不同组织中Cd的微区分布特征，并结合Cd的生物动力学实验研究了其变化规律。结果显示空白对照组栉孔扇贝内脏、鳃和性腺组织的Cd主要分布在类金属硫蛋白（MTLP）和细胞器中，闭壳肌组织中Cd主要分布在MTLP（占84.6%）。在Cd的富集实验中，内脏和鳃组织中MTLP和富含金属颗粒（MRG）中Cd的含量和所占百分比升高最显著，而细胞器中Cd的百分比明显下降；性腺组织中MTLP、细胞器和MRG组分中Cd的含量均明显升高，其中MRG中Cd的百分比升高，MTLP和细胞器中Cd的百分比逐渐下降；闭壳肌组织中MTLP和MRG中Cd的含量均显著上升，其中MRG组分中Cd的百分比显著升高。在释放Cd的实验中，内脏和鳃组织的MTLP中Cd的含量显著下降，而细胞器、热敏感蛋白（HSP）和MRG中Cd的含量和所占百分比逐渐升高，性腺组织各亚细胞组分中Cd含量均明显下降，但各亚细胞组分中Cd的百分比变化不明显；闭壳肌组织MTLP和MRG中Cd的含量下降，且MRG组分中Cd所占的百分比不断下降。本研究首次表明栉孔扇贝不同组织中Cd在亚细胞组分中的分布特征不同，并且在富集和释放Cd的过程中，内脏和鳃组织中的Cd在各亚细胞组分中不断发生调节和重新分配。

关键词:栉孔扇贝;镉(Cd);亚细胞组分分布;生物动力学

Abstract:

In order to explain the high capability of the scallop Chlamys farreri for cadmium accumulation, the subcellular distribution of Cd in the different tissues of the scallop C. farreri and its relationship between subcellular distribution and metal biokinetics was investigated. The results showed that for the control group, the metallothionein-like protein (MTLP) and the cell organelles were the main detoxification pools for the digestive gland, gills and gonad, and MTLP was the main pool for the adductor muscle. During the accumulation experiment, for the digestive glands and gills, the content and the percentage of Cd in the MTLP and the metal-rich granule(MRG) were all significantly increased, but the percentage of Cd in the cell organelles decreased. The Cd content in the MTLP, cell organelles and MRG in the gonad were all significantly increased, but the percentage of Cd in the MTLP and cell organelles kept decreasing with the percentage of Cd in the MRG increased. For the adductor muscle, when exposed to Cd, the Cd content in the MTLP and MRG significantly increased, and the percentage of Cd in the MRG was also significantly increased. During the elimination experiment, for the digestive glands and gills, the content of Cd in the MTLP was significantly decreased, at the same time, the content of Cd and the percentage of Cd in the cell organelles, heat-sensitive protein (HSP) and MRG kept increasing; for the gonad, the Cd content in every subcellular fractions decreased obviously, but the percentage of Cd in different subcellular fractions had no obvious change. For the adductor muscle, Cd content in the MTLP and MRG significantly decreased, and the percentage of Cd in MRG also kept decreasing. Present results first disclosed that the subcellular distribution of Cd was different for different tissues in the scallop C. farreri, and the redistribution of Cd in different subcellular fractions in the digestive gland and gills occurred during Cd accumulation and elimination.

Key words:Chlamys farreri;cadmium;subcellular distribution;metal biokinetics