Long-term exposure to near-future ocean acidification does not affect the expression of neurogenesis- and synaptic transmission-related genes in the olfactory bulb of European sea bass (Dicentrarchus labrax)

Abstract

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.

Molecular basis of parental contributions to the behavioural tolerance of elevated pCO2in a coral reef fish

“…Identification of these upregulated genes in all offspring regardless of parental phenotype suggests tolerance or sensitivity to elevated pCO 2 cannot protect these fish from this vicious cycle under short-term exposures. However, the absence of differential expression of these genes and pathways in offspring exposed transgenerationally to elevated pCO 2 suggests that acclimation via stabilization of acid-base regulation occurs with long-term exposure [ 58 ].…”

Responses of early life stages of European abalone (Haliotis tuberculata) to ocean acidification after parental conditioning: Insights from a transgenerational experiment

“…Negative RT controls were performed for all samples (RT reaction without retrotranscriptase enzyme). Transcript expression was quantified using the CFX96 Touch Real-Time PCR Detection system (Bio-Rad Laboratories Inc.) according to the protocol previously described by Mazurais et al (2020). The relative quantity of messenger was normalized with the ΔCt method using the same CFX Manager software (Bio-Rad Laboratories Inc.).…”

Ocean Acidification Alters the Acute Stress Response of a Marine Fish

“…Journal Pre-proof axis, iii) alterations in neurotransmitter hypothalamic levels and iv) modified behavioral traits associated to motor activity. The model species chosen for this study is the European sea bass, Dicentrarchus labrax, an economically important marine teleost, whose physiological and behavioral response to acidified condition (Pope, Ellis et al 2014, Duteil, Pope et al 2016, Crespel, Zambonino-Infante et al 2017, Poulton, Porteus et al 2017, Cominassi, Moyano et al 2019, Alves, Gregorio et al 2020, Mazurais, Servili et al 2020a, Servili, Canario et al 2020 and to an acute stress separately is known (Samaras, Dimitroglou et al 2016, Alfonso, Sadoul et al 2019, Ferrari, Rey et al 2020.…”