Thakkar Yax, Kobets T, Api Anne Marie, Duan J D, Williams G M
Research Institute for Fragrance Materials, Inc., Mahwah, New Jersey, USA.
Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York, USA.
Environ Mol Mutagen. 2025 Jun;66(5):243-257. doi: 10.1002/em.70015. Epub 2025 May 12.
The Chicken Egg Genotoxicity Assay (CEGA) is an avian egg-based model that utilizes the livers of developing chicken embryo-fetuses to assess the ability of chemicals to produce direct DNA damage. The main goal of the study was to evaluate target tissue exposure and metabolism in the CEGA to assess its suitability as a biologically relevant new approach methodology (NAM) for detecting the genotoxic potential of chemicals. An imaging study using two-photon excitation microscopy after the administration of a fluorescent dye (acridine orange) verified that chemicals following administration into the air sac of the fertilized chicken egg reach the target organ, liver. A metabolism study using liquid chromatography with high resolution mass spectrometry (LC/MS), conducted after the administration of benzo(a)pyrene (B(a)P) according to the CEGA protocol, confirmed the formation of sufficient amounts of reactive metabolite(s) responsible for the genotoxic effects of a parent compound upon reaching the target tissue. Moreover, an RNA sequencing study revealed that B(a)P in embryo-fetal chicken livers significantly upregulated several genes responsible for the activity of the CYP1A1 enzyme, which is critical for the bioactivation of B(a)P. These findings, along with the previously reported DNA damage (i.e., DNA adducts and single-strand breaks) produced by B(a)P in CEGA, support sufficient target tissue exposure to B(a)P and the ability of avian fetal livers to bioactivate B(a)P to a reactive intermediate. Overall, the findings in the study support the conclusion that the CEGA can be considered a robust potential alternative to the animal testing strategy for assessing the genotoxic potential of chemicals.
鸡胚遗传毒性试验（CEGA）是一种基于禽蛋的模型，它利用发育中的鸡胚胎儿的肝脏来评估化学物质产生直接DNA损伤的能力。该研究的主要目标是评估CEGA中靶组织的暴露和代谢情况，以评估其作为一种生物学相关的新方法学（NAM）来检测化学物质遗传毒性潜力的适用性。在施用荧光染料（吖啶橙）后使用双光子激发显微镜进行的成像研究证实，将化学物质施用于受精鸡蛋的气囊后可到达靶器官肝脏。按照CEGA方案施用苯并(a)芘（B(a)P）后，使用液相色谱-高分辨率质谱（LC/MS）进行的代谢研究证实，母体化合物到达靶组织后会形成足够量的负责其遗传毒性作用的活性代谢物。此外，一项RNA测序研究表明，鸡胚胎儿肝脏中的B(a)P显著上调了几个负责CYP1A1酶活性的基因，而该酶对B(a)P的生物活化至关重要。这些发现，连同之前报道的B(a)P在CEGA中产生的DNA损伤（即DNA加合物和单链断裂），支持了靶组织对B(a)P有足够的暴露以及禽胎儿肝脏将B(a)P生物活化为活性中间体的能力。总体而言，该研究结果支持以下结论：CEGA可被视为评估化学物质遗传毒性潜力的动物试验策略的一种强大潜在替代方法。
