School of Veterinary Medicine, Department of Anatomy, Physiology and Cell Biology, University of California, Davis, California 95616, USA.
BMC Genomics. 2009 Dec 15;10:608. doi: 10.1186/1471-2164-10-608.
The delta smelt (Hypomesus transpacificus) is a pelagic fish species listed as endangered under both the USA Federal and Californian State Endangered Species Acts and considered an indicator of ecosystem health in its habitat range, which is limited to the Sacramento-San Joaquin estuary in California, USA. Anthropogenic contaminants are one of multiple stressors affecting this system, and among them, current-use insecticides are of major concern. Interrogative tools are required to successfully monitor effects of contaminants on the delta smelt, and to research potential causes of population decline in this species. We have created a microarray to investigate genome-wide effects of potentially causative stressors, and applied this tool to assess effects of the pyrethroid insecticide esfenvalerate on larval delta smelt. Selected genes were further investigated as molecular biomarkers using quantitative PCR analyses.
Exposure to esfenvalerate affected swimming behavior of larval delta smelt at concentrations as low as 0.0625 mug.L-1, and significant differences in expression were measured in genes involved in neuromuscular activity. Alterations in the expression of genes associated with immune responses, along with apoptosis, redox, osmotic stress, detoxification, and growth and development appear to have been invoked by esfenvalerate exposure. Swimming impairment correlated significantly with expression of aspartoacylase (ASPA), an enzyme involved in brain cell function and associated with numerous human diseases. Selected genes were investigated for their use as molecular biomarkers, and strong links were determined between measured downregulation in ASPA and observed behavioral responses in fish exposed to environmentally relevant pyrethroid concentrations.
The results of this study show that microarray technology is a useful approach in screening for, and generation of molecular biomarkers in endangered, non-model organisms, identifying specific genes that can be directly linked with sublethal toxicological endpoints; such as changes in expression levels of neuromuscular genes resulting in measurable swimming impairments. The developed microarrays were successfully applied on larval fish exposed to esfenvalerate, a known contaminant of the Sacramento-San Joaquin estuary, and has permitted the identification of specific biomarkers which could provide insight into the factors contributing to delta smelt population decline.
尖吻鲈（Hypomesus transpacificus）是一种远洋鱼类，在美国联邦和加利福尼亚州濒危物种法案中均被列为濒危物种，被认为是其栖息地范围内生态系统健康的指标，其栖息地范围仅限于美国加利福尼亚州的萨克拉门托-圣华金河口。人为污染物是影响该系统的多种胁迫因素之一，其中，目前使用的杀虫剂是主要关注点。需要有探究性工具来成功监测污染物对尖吻鲈的影响，并研究该物种种群减少的潜在原因。我们已经创建了一个微阵列来研究潜在致病胁迫因素对基因组范围的影响，并应用该工具来评估拟除虫菊酯杀虫剂 esfenvalerate 对幼鱼尖吻鲈的影响。选择的基因进一步通过定量 PCR 分析作为分子生物标志物进行了研究。
暴露于 esfenvalerate 以低至 0.0625 µg/L 的浓度就会影响幼鱼的游泳行为，并且在涉及神经肌肉活动的基因中测量到了显著的差异。与免疫反应、细胞凋亡、氧化还原、渗透胁迫、解毒以及生长和发育相关的基因表达的改变似乎是由 esfenvalerate 暴露引起的。游泳障碍与参与脑细胞功能的酶天冬氨酸氨甲酰转移酶（ASPA）的表达显著相关，ASPA 与许多人类疾病有关。选择了一些基因作为分子生物标志物进行研究，并确定了在暴露于环境相关拟除虫菊酯浓度的鱼类中，ASPA 下调与观察到的行为反应之间存在很强的关联。
本研究结果表明，微阵列技术是一种有用的筛选方法，可用于筛选濒危非模式生物中的潜在生物标志物，并生成可直接与亚致死毒理学终点相关的特定基因；例如，神经肌肉基因表达水平的变化导致可测量的游泳障碍。成功地将开发的微阵列应用于暴露于 esfenvalerate 的幼鱼，esfenvalerate 是萨克拉门托-圣华金河口的一种已知污染物，并确定了特定的生物标志物，这可以深入了解导致尖吻鲈种群减少的因素。
