| The black tiger shrimp, Penaeus monodon, is one of the most widely cultured shrimp species in the world. In 1992, the shrimp industry began facing problems, which includes pathogenic diseases and the difficulty in shrimp breeding. To induce shrimp spawning, female broodstock must undergo eyestalk ablation, which results in ovarian development and spawning, but also causes devastating effects on health and lifespan of the broodstock. Eicosanoid pathway is one of the pathways that are involved in ovarian development in all major invertebrate and vertebrate phyla. Therefore, examining the existence of this pathway and its gene expressions in P. monodon may provide us a better understanding of the mechanism that controls shrimp spawning and ovarian development. Here we discovered that one of the genes in the eicosanoid pathways called 5-lipoxygenase is expressed in the ovary cDNA of the P. monodon mature female broodstock. This gene is also expressed in the haemocytes, heart, and thoracic ganglia of the mature female broodstock. To follow the expression of 5-lipoxygenase gene through shrimp development, real-time PCR was also performed in juvenile shrimp organs. We discovered that 5-lipoxygenase gene is expressed in the haemocytes of juvenile female shrimp, but not in the ovary. Furthermore, the expression of this gene increases in haemocytes and ovary as the shrimp mature. These results support our hypothesis that the 5-lipoxygenase gene may be involved in the reproduction system of P. monodon. Hopefully this initial study can lead to further study and eventually lead to the discovery of an alternative method to induce ovarian maturation and spawning. |