Department of Biology, Brandon University, Brandon, Manitoba, R7A 6A9, Canada.
Department of Biology, Brandon University, Brandon, Manitoba, R7A 6A9, Canada.
Environ Pollut. 2018 Dec;243(Pt A):591-600. doi: 10.1016/j.envpol.2018.08.084. Epub 2018 Aug 27.
Over the last few decades, plastic waste has become an increasing environmental concern as it accumulates in every environment on our planet. Though traditionally seen as a macroscopic problem (i.e., large plastic debris), plastic pollution is also evident at smaller scales. Indeed, the intentional industrial production of small plastic particles and the physical degradation of larger plastic debris have overtime resulted in an increased environmental prevalence of smaller plastic particles, including microplastics. While the effects of these small polymers on marine biota have been an important research focus, recent global surveys indicate that our freshwater lakes and rivers are also plagued by microplastics. However, despite these discoveries we currently have a limited understanding of the impact these particles may have on freshwater animals, particularly on vertebrate species. Thus, the aim of the present study was to assess the impact of high concentrations of microplastics (5 and 20 mg.L) on the early life stages in zebrafish, a model freshwater vertebrate model. To do this, we exposed embryonic and larval zebrafish to fluorescently labelled polyethylene microspheres for up to 14 days and assessed their microplastic content, growth, hatching and oxygen consumption rates. We then explored the molecular underpinnings of the microplastic response by RNA sequencing. Over the course of the exposure, we observed a consistent accumulation of microplastics in the gastrointestinal tract of the fish in a concentration dependent manner, but could not detect any detrimental effects of these particles on larval development, growth or metabolism. However, whole animal transcriptomics revealed that microplastics induced a transient and extensive change in larval gene expression within 48 h exposure, which largely disappeared by 14 days. However, as these transcriptional changes occurred during a critical period of larval development, we suggest that an evaluation of the potential long-term impact of these particles is warranted.
在过去的几十年中，塑料废物在我们星球的每个环境中不断积累，已成为日益严重的环境问题。虽然传统上认为塑料污染是一个宏观问题（即，大型塑料碎片），但在较小的尺度上也可以明显看到塑料污染。事实上，小型塑料颗粒的有意工业生产和较大塑料碎片的物理降解，已经导致较小塑料颗粒（包括微塑料）在环境中的存在增加。虽然这些小聚合物对海洋生物群的影响一直是一个重要的研究重点，但最近的全球调查表明，我们的淡水湖泊和河流也受到微塑料的困扰。然而，尽管有这些发现，我们目前对这些颗粒可能对淡水动物，特别是脊椎动物物种的影响的了解有限。因此，本研究的目的是评估高浓度微塑料（5 和 20mg.L）对斑马鱼早期生命阶段的影响，斑马鱼是一种淡水脊椎动物模型。为此，我们将荧光标记的聚乙烯微球暴露于胚胎和幼鱼斑马鱼中长达 14 天，并评估它们的微塑料含量、生长、孵化和耗氧率。然后，我们通过 RNA 测序探索了微塑料反应的分子基础。在暴露过程中，我们观察到微塑料在鱼的胃肠道中以浓度依赖的方式持续积累，但未检测到这些颗粒对幼鱼发育、生长或代谢的任何有害影响。然而，全动物转录组学显示，微塑料在暴露 48 小时内诱导了幼鱼基因表达的短暂而广泛的变化，而在 14 天时这些变化大多消失。然而，由于这些转录变化发生在幼鱼发育的关键时期，我们建议评估这些颗粒的潜在长期影响是必要的。
