The decrease in ocean pH that results from the increased concentration of dissolved carbon dioxide (CO2) is likely to influence many physiological functions in organisms. It has been shown in different fish species that ocean acidification (OA) mainly affects sensory systems, including olfaction. Impairment of olfactory function may be due to a dysfunction of the GABAergic system and to an alteration of neuronal plasticity in the whole brain and particularly in olfactory bulbs. Recent studies revealed that OA-driven effects on sensory systems are partly mediated by the regulation of the expression of genes involved in neurotransmission and neuronal development. However, these studies were performed in fish exposed to acidified waters for short periods, of only a few days. In the present paper, we investigated whether such effects could be observed in adult (4-years old) European sea bass (Dicentrarchus labrax) exposed to two hypercapnic and acidified conditions (PCO2 ≈ 980 µatm; pH total = 7.7 and PCO2 ≈ 1520 µatm; pH total = 7.5) from the larval stage. In a first approach, we analyzed by qPCR the expression of five genes involved in neurogenesis (DCX) or expressed in GABAergic (Gabra3), glutamatergic (Gria1) or dopaminergic (TH and DDC) neurons in the olfactory bulbs. The tested experimental conditions did not change the expression of any of the five genes. This result would indicate that a potential disruption of the olfactory function of sea bass exposed for a long term to near-future OA, either occurs at a level other than the transcriptional one or involves other actors of the sensory function.

中文翻译：

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长期暴露于近期海洋酸化不会影响欧洲鲈鱼（Dicentrarchus labrax）嗅球中神经发生和突触传递相关基因的表达

由溶解的二氧化碳 (CO2) 浓度增加引起的海洋 pH 值降低可能会影响生物体的许多生理功能。已经在不同的鱼类中表明，海洋酸化 (OA) 主要影响感官系统，包括嗅觉。嗅觉功能受损可能是由于 GABA 能系统的功能障碍和整个大脑，特别是嗅球中神经元可塑性的改变。最近的研究表明，OA 对感觉系统的影响部分是由参与神经传递和神经元发育的基因表达的调节介导的。然而，这些研究是在短时间（仅几天）暴露于酸化水域的鱼中进行的。在本文中，我们研究了在暴露于两种高碳酸血症和酸化条件（PCO2 ≈ 980 µatm；pH 总量 = 7.7 和 PCO2 ≈ 1520 µatm；pH 总量 = 7.5）的成年（4 岁）欧洲鲈鱼（Dicentrarchus labrax）中是否可以观察到这种影响) 从幼虫阶段。在第一种方法中，我们通过 qPCR 分析了嗅球中涉及神经发生 (DCX) 或在 GABA 能 (Gabra3)、谷氨酸能 (Gria1) 或多巴胺能 (TH 和 DDC) 神经元中表达的五种基因的表达。测试的实验条件没有改变五种基因中任何一种的表达。这一结果表明，长期暴露于近期 OA 的鲈鱼嗅觉功能的潜在破坏，要么发生在转录水平以外的水平，要么涉及感官功能的其他参与者。