全氟辛酸(PFOA)对菲律宾蛤仔血淋巴的毒性效应研究
Toxicity Effects of Perflurooctanoic Acid (PFOA) on Ruditapes philippinarum Hemocytes
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摘要: 全氟辛酸(perfluorooctanoic acid, PFOA)是海洋环境中的一类新兴污染物。双壳贝类常被用于评估污染物毒性和监测生态环境，是海洋生态系统的重要指示物种。血细胞是双壳贝类免疫系统的主要组成部分，其相关指标的变化对评估PFOA的污染状况具有重要意义。本研究测量了PFOA在菲律宾蛤仔(Ruditapes philippinarum)血淋巴细胞中的生物蓄积含量和免疫相关指标，包括血细胞总数(total hemocyte count, THC)、细胞活性、细胞凋亡、吞噬活性、活性氧(reactive oxygen species, ROS)和非特异性酯酶活性，从免疫器官、免疫功能以及免疫因子3个方面系统评估PFOA对贝类的免疫毒性。结果显示：PFOA在血淋巴中大量蓄积，实验第14天时PFOA在3个处理组中的含量分别为(122.5±5.35)、(149.38±0.52)、(157.23±4.65) ng·mL-1。清水恢复7 d后，各处理组中PFOA的蓄积量虽有所下降，但仍分别高达(3.33±0.16)、(5.42±0.08)、(6.20±0.20) ng·mL-1。进一步研究发现，PFOA的胁迫可引发蛤仔血细胞各生理指标及免疫功能的显著变化。PFOA以浓度依赖性方式缩减了蛤仔血细胞总数，改变了血细胞组成比例，细胞活力及吞噬活性明显下降，ROS大量生成，凋亡率大幅增加，非特异性酯酶活性明显增强。且清水恢复7 d各指标仍未能恢复到对照组水平。此外，在分子水平上，PFOA的暴露亦显著改变了免疫相关基因的表达。可见，PFOA的胁迫可对菲律宾蛤仔产生明显的免疫毒性效应。该研究为揭示PFOA对海洋生态系统的潜在风险和筛选海洋中全氟及多氟烷基物质(PFASs)污染的生物指示因子提供一定的科学依据。Abstract: Perfluorooctanoic acid (PFOA) is an emerging contaminant in the marine environment. Bivalves are important indicator species in marine environment, which are commonly used to assess pollutants toxicity and monitor the ecological environment. Hemocytes are the main component of immune system in bivalves, and are often used to indicate the immunotoxicity of pollutants. In this study, PFOA bioaccumulation in hemolymph and immune-related indicators, including total hemocyte count (THC), hemocyte viability, apoptosis, phagocytosis, reactive oxygen species (ROS), and non-specific esterase activity in Ruditapes philippinarum, were measured. We intended to systematically assess PFOA immunotoxicity from three perspectives, including immune organs, immune functions, and immune factors. The results indicated that PFOA accumulated significantly in the hemolymph. After 14 days of PFOA exposure, the contents were (122.5±5.35), (149.38±0.52), and (157.23±4.65) ng·mL-1 in hemolymph from treatment groups of PFOA-L, PFOA-M, and PFOA-H, respectively. After a 7-day sea water recovery period, the accumulation of PFOA in three treatment groups were still significantly higher than the control group, and were (3.33±0.16), (5.42±0.08), (6.20±0.20) ng·mL-1, respectively. We further discovered that PFOA exposure triggered significant changes in various physiological indexes and immune functions in clam hemocytes. PFOA reduced the THC of clams in a dose-dependent manner, changed the proportions of different types of hemocytes. Meanwhile, PFOA also caused a decline in phagocytic ability, and increase in the levels of ROS and non-specific esterase. In addition, PFOA exposure also significantly altered the expression levels of immune-related genes. After a 7-day sea water recovery period, the above indicators had not returned to the level of the control group. It was evident that PFOA exposure triggered significant immunotoxic effects in R. philippinarum. This study provides scientific basis for revealing the potential risk of PFOA to the marine ecosystem and scientific evidence for screening bioindicators for per- and polyfluoroalkyl substances (PFASs) pollution in the oceans.
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Key words:
- perfluorooctanoic acid /
- Ruditapes philippinarum /
- immunotoxicity /
- hemocytes /
- ecological risk
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