The prostanoid pathway converts polyunsaturated fatty acids (PUFAs) into bioactive lipid mediators, including prostaglandins, thromboxanes and prostacyclins, all of which play vital roles in the immune and reproductive systems in most animal phyla. different stages of shrimp ovaries, we found that the amounts of gene transcripts and PGF2 decreased as the ovaries matured. These findings not only indicate the presence of a functional prostanoid pathway in penaeid shrimp, but also suggest a possible role of the PGF2 biosynthesis in shrimp ovarian development. Introduction Prostanoids are oxygenated derivatives of C-20 polyunsaturated fatty acids (PUFAs) that play active roles in inflammation, immune response, cardiovascular control and reproduction in most animals [1-3]. These PUFAs, which serve as precursors of the prostanoid pathway, include arachidonic acid (AA), Rabbit polyclonal to LRCH4 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The prostanoid pathway begins with the enzyme phospholipase A2, which releases AA from the phospholipids of cellular and intracellular membranes . The released AA is then cyclized and subsequently reduced by the cyclooxygenase (COX) enzyme to form prostaglandin G2 (PGG2) and prostaglandin H2 (PGH2), MGCD0103 (Mocetinostat) respectively [4,5]. Downstream enzymes, including prostaglandin and thromboxane synthases, later convert PGH2 to prostanoids, such as prostaglandins, prostacyclins and thromboxanes, which serve as signaling molecules in various physiological responses [3,6]. The presence of PUFAs and prostaglandins in crustaceans has long been the focus of aquaculture research. All three prostanoid precursors (AA, EPA and DHA) have been identified in the Chinese prawn , the Pacific white shrimp , the green tiger prawn , the kuruma prawn [10,11], the banana shrimp  and [13,14]. In addition, EPA has been identified in the common?littoral?crab  and the Atlantic blue crab , while DHA has been detected in the crayfish . On the other hand, prostaglandin E2 (PGE2) and prostaglandin F2 (PGF2) have been identified in  and the Florida crayfish [18,19]. Prostaglandin D2 (PGD2), PGE2 and PGF2 have been detected in the fresh water field crab , while PGE2, thromboxane B2 (TXB2) and 6-keto-PGF1 have been reported in . In addition, PGE2 has been identified in hemolymph, muscle and ovary of domesticated , but the presence of PGF2 has not been reported in this species. In crustaceans, one of the more prominent roles of prostanoids is the regulation of female reproductive maturation. For instance, the production of PGE2 and PGF2 is positively correlated with ovarian maturation in  and . Furthermore, injection of PGE2 and PGF2 into ovaries of significantly increased the number and the diameter of the oocytes in a dose-dependent manner . In domesticated . Nevertheless, these findings suggest a possible involvement of the prostanoid biosynthesis in crustacean female reproductive system. Although the production of prostanoids and their precursors is well-established in most crustaceans, prostanoid biosynthesis genes in these species are poorly characterized. Thus far, the only crustacean with a fully constructed prostanoid pathway is the fresh water flea ((and and . In marine crustaceans, genes have been identified in spp. and spp. , while genes have been characterized in , the American lobster (Accession: MGID155886 from the Marine Genomic Project)  and the sea lice and . Due to the roles of prostanoids in the reproductive system in most crustaceans, the characterization of the prostanoid pathway in economically valuable organisms, such MGCD0103 (Mocetinostat) as penaeid shrimp, is essential for both scientific gain and potential applications in aquaculture practice. In this study, we propose a scheme for the prostanoid pathway based on the identification of eight prostanoid biosynthesis genes, the detection of lipid precursors and prostaglandins, and the detection of prostaglandin synthase activity. The correlations observed among gene transcription, prostaglandin production, and ovarian maturation also suggest that prostaglandin biosynthesis may be involved in the regulation of the female reproductive system. Results Identification of prostanoid biosynthesis genes Based on available EST sequences from The Black Tiger Shrimp EST Project  and MGCD0103 (Mocetinostat) the Marine Genomics Project , short fragments of prostanoid biosynthesis genes were amplified from shrimp ovary cDNA. RACE-PCR was used to obtain full-length gene sequences, resulting in the identification of nine putative prostanoid biosynthesis genes: (((((((((enzymes when compared with their closest homologs (Table 1). Table 1 TBLASTX analyses of prostanoid biosynthesis genes. Analysis of conserved residues and domains in and genes The putative prostanoid biosynthesis genes were submitted to the Conserved Domain Architecture Retrieval Tool (CDART) for protein domain prediction, revealing that the proteins contain the same domain types and positions as the prostanoid enzymes found in other species (Figure S1). At this point, and were examined in more details, as these genes are likely to be responsible for the biosynthesis of PGE2 and PGF2, which has been shown to affect ovarian development in other crustaceans [10,18,20]. In have been cloned and characterized, namely and or is a member of the Membrane-Associated Protein involved in.