Schoeny R, Cody T, Warshawsky D, Radike M
U.S. Environmental Protection Agency, Environmental Criteria and Assessment Office, Cincinnati, OH 45268.
Mutat Res. 1988 Feb;197(2):289-302. doi: 10.1016/0027-5107(88)90099-1.
Polycyclic aromatic hydrocarbons (PAH) known to produce carcinogenic and mutagenic effects have been shown to contaminate waters, sediments and soils. While it is accepted that metabolites of these compounds are responsible for most of their biological effects in mammals, their metabolism, and to a large extent their bioactivity, in aquatic plants have not been explored. Cultures of photosynthetic algal species were assayed for their ability to metabolize benzo[a]pyrene (BaP), a carcinogenic PAH under conditions which either permitted (white light) or disallowed (gold light) photooxidation of the compound. Growth of Selenastrum capricornutum, a fresh-water green alga, was completely inhibited when incubated in white light with 160 micrograms BaP/l medium. By contrast concentrations at the upper limit of BaP solubility in aqueous medium had no effect on algal growth when gold light was used. BaP quinones and phenol derivatives were found to inhibit growth of Selenastrum under white light incubation. BaP phototoxicity and metabolism were observed to be species-specific. All 3 tested species of the order Chlorococcales were growth-inhibited by BaP in white light whereas neither the green alga Chlamydomonas reinhardtii nor a blue-green, a yellow-green or an euglenoid alga responded in this fashion. Assays of radiolabeled BaP metabolism in Selenastrum showed that the majority of radioactivity associated with BaP was found in media as opposed to algal cell pellets, that the extent of metabolism was BaP concentration dependent, and that the proportion of various metabolites detected was a function of the light source. After gold light incubation, BaP diols predominated while after white light treatment at equal BaP concentrations, the 3,6-quinone was found in the highest concentration. Extracted material from algal cell pellets and from media was tested for mutagenicity in a forward mutation suspension assay in Salmonella typhimurium using resistance to 8-azaguanine for selection. Direct-acting mutagens were detected in extracted media from incubation of Selenastrum with 400 micrograms BaP/l for 1 day in gold light. Extracts of media from algae incubated in gold light from 1 to 4 days with 1200 micrograms BaP/l were found to have direct-acting mutagens as well as those requiring further metabolism. Media extracts from white light incubations of BaP were mutagenic upon addition of rat liver homogenates. Activity of these materials from white light treatment are largely attributable to unmetabolized BaP.
已知具有致癌和致突变作用的多环芳烃（PAH）已被证明会污染水体、沉积物和土壤。虽然人们公认这些化合物的代谢产物是其在哺乳动物中产生大多数生物学效应的原因，但它们在水生植物中的代谢情况，以及在很大程度上它们的生物活性，尚未得到研究。对光合藻类物种的培养物进行了检测，以评估它们在允许（白光）或不允许（金光）该化合物光氧化的条件下代谢苯并[a]芘（BaP）（一种致癌性PAH） 的能力。当在含有160微克BaP/升培养基的白光下培养时，淡水绿藻羊角月牙藻（Selenastrum capricornutum）的生长完全受到抑制。相比之下，当使用金光时，BaP在水介质中的溶解度上限浓度对藻类生长没有影响。发现BaP醌和酚衍生物在白光培养下会抑制羊角月牙藻的生长。观察到BaP的光毒性和代谢具有物种特异性。绿球藻目所有3个受试物种在白光下均受到BaP的生长抑制，而绿藻莱茵衣藻（Chlamydomonas reinhardtii）以及蓝藻、黄绿藻或裸藻均未出现这种反应。对羊角月牙藻中放射性标记的BaP代谢进行的检测表明，与BaP相关的大部分放射性存在于培养基中，而非藻类细胞沉淀中，代谢程度取决于BaP浓度，并且检测到的各种代谢产物的比例是光源的函数。在金光培养后，BaP二醇占主导，而在相同BaP浓度的白光处理后，发现3,6-醌的浓度最高。使用对8-氮杂鸟嘌呤的抗性进行选择，在鼠伤寒沙门氏菌的正向突变悬浮试验中，对从藻类细胞沉淀和培养基中提取的物质进行了致突变性测试。在金光下将羊角月牙藻与400微克BaP/升一起培养1天的培养基提取物中检测到直接作用的诱变剂。在金光下将藻类与1200微克BaP/升一起培养1至4天的培养基提取物中发现既有直接作用的诱变剂，也有需要进一步代谢的诱变剂。BaP白光培养的培养基提取物在加入大鼠肝脏匀浆后具有致突变性。这些来自白光处理的物质的活性很大程度上归因于未代谢的BaP。
