Morphological description of blood, ontogeny of lymphoid organs and analysis of the expression of genes related to the immune system of the sole Paralichthys orbignyanus
This study describes the ontogeny of the innate and adaptive immune system of the sole Paralichthys orbignyanus and analyzes the expression of RAG1, CD3, CD4-2 and IL-1β genes, related to the development of the immune system in larvae and juveniles of P. orbignyanus, and to peripheral blood morphology. Larviculture was carried out at the Estuarine and Marine Pisciculture Laboratory of the Federal University of Rio Grande (EMA - FURG). The kidney appeared 1 day after hatching (dah), the thymus at 5 dah and the spleen at 10 dah, with lymphoid cells observed around 25 dah. The expression of the RAG1 gene followed the appearance of the thymus, and the mRNA levels of CD3 and CD4-2 increased after 30 dah. An increase in the levels of the cytokine IL-1B was observed at 30 dah. The blood of P. orbignyanus basically follows the same pattern as other vertebrates (erythrocytes, leukocytes and thrombocytes). These results suggest that, from 25-30 dah onwards, the sole's immune system may show immunological memory, and immunostimulants and vaccination can be used to improve survival rates during larviculture, as well as the normal blood cell profile may serve as basis for future analysis of pathological conditions.