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Differential responses in the biotransformation systems of the oyster Crassostrea gigas (Thunberg, 1789) elicited by pyrene and fluorene: Molecular, biochemical and histological approach - Part II.
Aquatic Toxicology ( IF 4.5 ) Pub Date : 2020-07-09 , DOI: 10.1016/j.aquatox.2020.105565
Isis Mayna Martins Dos Reis 1 , Marília Nardelli Siebert 1 , Flávia Lucena Zacchi 1 , Jacó Joaquim Mattos 2 , Fabrício Flores-Nunes 1 , Guilherme de Toledo-Silva 3 , Clei Endrigo Piazza 1 , Márcia Caruso Bícego 4 , Satie Taniguchi 4 , Cláudio Manoel Rodrigues de Melo 5 , Afonso Celso Dias Bainy 1
Affiliation  

Pyrene (PYR) and fluorene (FLU) are among the sixteen priority Polycyclic Aromatic Hydrocarbons (PAH) of the United States Environmental Protection Agency and are both frequently detected in contaminated sites. Due to the importance of bivalve mollusks in biomonitoring programs and the scarce information on the biotransformation system in these organisms, the aim of this study was to investigate the effect of PYR and FLU at the transcriptional level and the enzymatic activities of some biotransformation systems in the Pacific oyster Crassostrea gigas, and to evaluate the histological effects in their soft tissues. Oysters C. gigas were exposed for 24 h and 96 h to PYR (0.25 and 0.5 μM) and FLU (0.6 and 1.2 μM). After exposure, transcript levels of cytochrome P450 coding genes (CYP1-like, CYP2-like, CYP2AU2, CYP356A1, CYP17α-like), glutathione S tranferase genes (omega GSTO-like and microsomal, MGST-like) and sulfotransferase gene (SULT-like), and the activity of ethoxyresorufin O-deethylase (EROD), Glutathione S-transferase (GST) and microssomal GST (MGST) were evaluated in gills. Histologic changes were also evaluated after the exposure period. PYR and FLU bioconcentrated in oyster soft tissues. The half-life time of PYR in water was lower than fluorene, which is in accordance to the higher lipophilicity and bioconcentration of the former. EROD activity was below the limit of detection in all oysters exposed for 96 h to PYR and FLU. The reproductive stage of the oysters exposed to PYR was post-spawn. Exposure to PYR caused tubular atrophy in digestive diverticula, but had no effect on transcript levels of biotransformation genes. However, the organisms exposed for 96 h to PYR 0.5 μM showed higher MGST activity, suggesting a protective role against oxidative stress in gills of oysters under higher levels of PYR in the tissues. Increased number of mucous cells in mantle were observed in oysters exposed to the higher FLU concentration, suggesting a defense mechanisms. Oysters exposed for 24 h to FLU 1.2 μM were in the ripe stage of gonadal development and showed higher transcript levels of CYP2AU2, GSTO-like and SULT-like genes, suggesting a role in the FLU biotransformation. In addition, after 96 h of exposure to FLU there was a significant increase of mucous cells in the mantle of oysters but no effect was observed on the EROD, total GST and MGST activities. These results suggest that PAH have different effects on transcript levels of biotransformation genes and enzyme activities, however these differences could also be related to the reproductive stage.



中文翻译:

pyr和芴引起的牡蛎Crassostrea gigas(Thunberg,1789)的生物转化系统中的差异响应:分子,生化和组织学方法-第二部分。

yr(PYR)和芴(FLU)是美国环境保护局的16种优先多环芳烃(PAH)之一,并且经常在受污染的地点被发现。由于双壳类软体动物在生物监测程序中的重要性以及这些生物中有关生物转化系统的信息稀缺,因此本研究的目的是研究PYR和FLU在转录水平和某些生物转化系统中酶活性上的作用。太平洋牡蛎Crassostrea gigas,并评估其软组织的组织学作用。将牡蛎牡蛎暴露于PYR(0.25和0.5μM)和FLU(0.6和1.2μM)24小时和96小时。暴露后,细胞色素P450编码基因的转录水平(CYP1样,CYP2样,CYP2AU2,CYP356A1,CYP17α样),谷胱甘肽S转移酶基因(欧米茄GSTO和微粒体,MGST样)和磺基转移酶基因(SULT样),以及乙氧基雷索芬O-脱乙基酶的活性(EROD),谷胱甘肽S评估evaluated中的β-转移酶(GST)和微粒体GST(MGST)。暴露期后还评估组织学变化。PYR和FLU生物浓缩在牡蛎软组织中。PYR在水中的半衰期比芴短,这与前者较高的亲脂性和生物浓度有关。在暴露于PYR和FLU 96 h的所有牡蛎中,EROD活性均低于检出限。暴露于PYR的牡蛎的生殖阶段是产卵后。暴露于PYR会引起消化憩室中的肾小管萎缩,但对生物转化基因的转录水平没有影响。然而,暴露于96μgPYR 0.5μM的生物体显示出更高的MGST活性,表明在较高PYR水平下牡蛎g的氧化应激具有保护作用。在暴露于较高FLU浓度的牡蛎中观察到地幔中粘液细胞的数量增加,表明防御机制。暴露于FLU 1.2μM24小时的牡蛎处于性腺发育的成熟阶段,并显示出较高的转录本水平。CYP2AU2GSTOSULT样基因提示在FLU生物转化中起作用。此外,暴露于FLU 96小时后,牡蛎地幔中的粘液细胞显着增加,但未观察到对EROD,总GST和MGST活性的影响。这些结果表明PAH对生物转化基因的转录水平和酶活性有不同的影响,但是这些差异也可能与生殖阶段有关。

更新日期:2020-07-15
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