Potential Implications of Acid-Sensing Ion Channels ASIC2 and ASIC4 in Gonadal Differentiation of IDicentrarchus labrax/I Subjected to Water Temperature Increase during Gonadal Development

• Published in: Animals (Basel) 2024-04, Vol.14 (7)
• Main Authors: Mhalhel, Kamel, Arena, Rosaria, Rizzo, Maria, Piccione, Giuseppe, Aragona, Marialuisa, Levanti, Maria, Aragona, Francesca, Arfuso, Francesca
• Format: Article
• Language: English
• Subjects: Amino acids; Fishes; Ion channels
• ISSN: 2076-2615; 2076-2615
• DOI: 10.3390/ani14071024

The seabass, Dicentrarchus labrax (D. labrax) is a gonochoristic species that shows clearly sex-linked growth. In fact, females grow faster and reach larger sizes than males. The expression of acid-sensing ion channels (ASICs) 2 and 4 (ASIC2 and ASIC4) in the gonads of Dicentrarchus labrax subjected to water temperature increased from 15 °C to 20 °C during the gonadal development. Water temperature during gonadal develepment modified both gonadal differentiation and growth in Dicentrarchus labrax. The incidence of intratesticular oocytes highlights intersexual cases, strengthening the possibility that water temperature could modulate sex differentiation in D. labrax. The results gathered in the study suggest the possible role of acid-sensing ion channels in gonad differentiation and gamete development in D. labrax. In this study, the expression and implication of acid-sensing ion channels 2 and 4 (ASIC2 and ASIC4) in the gonadal sex differentiation of Dicentrarchus labrax (D. labrax), subjected to increasing water temperatures during gonadal development, were evaluated. Two groups were selected: a control group (CG), in which the average water temperature was maintained at 15 °C and increased to 20 °C in 20 days until weaning; and an experimental group (EG), in which the water temperature was retained at 15 °C for 60 days; thereafter, the temperature was increased daily by 0.5 °C until it reached 20 °C up to the weaning time. Ten fish from the CG and 13 fish from the EG were sampled randomly on the 335th day after hatching (dph). A higher percentage of gonad differentiation in ovaries rather than in testes was observed in the EG compared to the CG (p = 0.01). ASIC2 and ASIC4 were detected for the first time in D. labrax ovaries by indirect immunofluorescence. Both ASIC2 and ASIC4 were expressed in previtellogenic oocytes of ovaries and in scattered cells within some testes, and were most likely intratesticular previtellogenic oocytes in both the CG and EG groups. The CG group showed a higher expression of ASIC4 than the EG cohort (p < 0.05). The results gathered in this study revealed the capacity of water temperature to influence both gonadal differentiation and growth in this gonochoristic fish species, and suggests the possible role of ASIC2 and ASIC4 in gonad differentiation and gamete development in D. labrax.