Investigating Development and Defense Systems in Early Reproductive Stages of Male and Female Gonads in Black Scorpionfish Scorpaena porcus (Linnaeus, 1758)

The present study investigates the reproductive and immune defense systems in the gonads of black scorpionfish (Scorpaena porcus, Linnaeus 1758). This study concentrates on the initial phases of reproduction in both male and female fish and investigates the presence and function of an antimicrobial peptide, Piscidin-1. Histological analyses demonstrate morphological changes from the immature to developing stages in gonads. Immunohistochemical methods demonstrate strong reactivity to Piscidin-1 in germinal and somatic cells during early ontogeny, suggesting its crucial role in local defense mechanisms. This research contributes to the understanding of the interaction between reproductive biology and immune defense in S. porcus, offering insights that could benefit species conservation and management efforts. One of the most crucial biological indicators in tracking long-term variations in the reproductive cycle is sexual development. Scorpaena porcus (Linnaeus, 1758), commonly known as the black scorpionfish, is a small teleost from the family Scorpaenidae. Much is known about its ecology, but data on its reproductive and defense systems are still lacking. Antimicrobial peptides (AMPs), such as piscidins, are integral components of the innate immune system in fish. These peptides exhibit a wide range of activity against bacteria, fungi, viruses, and protozoa and act as the first line of host defense. This study aims to investigate the primary sexual development stages in male and female gonads of black scorpionfish, providing additional knowledge on the reproductive biology of this teleost while evaluating concomitant changes in the expression of a Piscidin-1 antimicrobial peptide. The results show a histological, morpho-structural change from the immature stage to the developing virgin stage. Immunohistochemical analyses show that germinal and somatic cells are strongly reactive to Piscidin-1 in both gonads at an early ontogeny stage. These data suggest that Piscidin-1 may play a key role in the local defense system of scorpionfish gonads at this delicate stage, which is critical for the continuation and maintenance of the species. The present findings are potentially useful for a better understanding of the reproductive cycle of this fish, improving our knowledge of the interaction between the immune system and reproduction.