Safety Measurement Institute, Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea.
Environmental Biology Research Group, Korea Institute of Toxicology, 17 Jegok-gil, Jinju 52834, Republic of Korea; Human and Environmental Toxicology Program, University of Science and Technology, Daejeon 34113, Republic of Korea.
Sci Total Environ. 2021 Aug 1;780:146405. doi: 10.1016/j.scitotenv.2021.146405. Epub 2021 Mar 17.
Machine vision techniques for monitoring heart rates in aquatic bioassays have been applied to cardiotoxicity assessment. However, the requisite large data sizes and long calculation times make long-term observations of heart rates difficult. In this study, we developed a real-time heart rate monitoring system for individual Daphnia magna in a water chamber mounter that immobilizes their movement in 100 mL media. Heart rates are calculated from real-time, time-resolved relative phase information from digital holograms acquired with a 200 fps camera and parallel computation using a graphics processing unit. With this system, we monitored the real-time changes in the heart rates of individual D. magna specimens exposed to HO as a positive control for reactive oxygen species (ROS) levels in an aquatic environment for 10 h, a period long enough to observe dynamic heart rate responses to the mounting process and exposure and to establish heart rate trends. An additional group analysis was conducted to compare to conventional cardiotoxicity assessment, with results of both assessments showing that the heart rates reduced according to ROS level by HO exposure concentration. Notably, the results of our real-time dynamic heart rate monitoring in aquatic conditions indicated that establishing a relaxation heart rate before measurements could improve the accuracy of toxicity assessment. It is believed that the system developed in this study, achieving the simultaneous measurement, analysis, and display of reconstructed results, will find wide application in other aquatic bioassays.
机器视觉技术已应用于水生生物测定中的心率监测，以进行心脏毒性评估。然而，所需的大数据量和长时间的计算时间使得长期观察心率变得困难。在这项研究中，我们开发了一种实时心率监测系统，用于在水室安装器中固定其运动的单个大型溞（Daphnia magna），在 100 mL 介质中。通过使用 200 fps 相机获取数字全息图并使用图形处理单元进行并行计算，从实时、时间分辨的相对相位信息中计算心率。使用该系统，我们监测了暴露于 HO 的单个 D. magna 样本的实时心率变化，HO 是水生环境中活性氧（ROS）水平的阳性对照，监测时间长达 10 小时，足以观察到动态心率对安装过程和暴露的反应，并建立心率趋势。进行了额外的组分析以与传统的心脏毒性评估进行比较，两种评估的结果均表明，心率随着 HO 暴露浓度的 ROS 水平降低而降低。值得注意的是，我们在水生条件下进行的实时动态心率监测结果表明，在测量前建立放松心率可以提高毒性评估的准确性。相信本研究开发的系统，实现了重建结果的同时测量、分析和显示，将在其他水生生物测定中得到广泛应用。
