Project description:BackgroundSerotonin is a phylogenetically ancient molecule that is widely distributed in most metazoans, including flatworms. In addition to its role as a neurotransmitter, serotonin acts as a morphogen and regulates developmental processes. Although several studies have focused on the serotonergic nervous system in parasitic flatworms, little is known on the role of serotonin in flatworm development.MethodsTo study the effects of serotonin on proliferation and development of the cestode Echinococcus multilocularis, we cloned the genes encoding the E. multilocularis serotonin transporter (SERT) and tryptophan hydroxylase (TPH), analyzed gene expression by transcriptome analysis and whole mount in situ hybridization (WMISH) and performed cell culture experiments.ResultsWe first characterized orthologues encoding the SERT and TPH, the rate-limiting enzyme in serotonin biosynthesis. WMISH and transcriptomic analyses indicated that the genes for both SERT and TPH are expressed in the parasite nervous system. Long-term treatment of parasite stem cell cultures with serotonin stimulated development towards the parasite metacestode stage. Mature metacestode vesicles treated with serotonin showed increased rates of incorporation of the thymidine analogue 5-ethynyl-2'-deoxyuridine (EdU), indicating stimulated cell proliferation. In contrast, treatment with the selective serotonin reuptake inhibitor paroxetine strongly affected the viability of parasite cells. Paroxetine also caused structural damage in metacestode vesicles, suggesting that serotonin transport is crucial for the integrity of parasite vesicles.ConclusionsOur results indicate that serotonin plays an important role in E. multilocularis development and proliferation, providing evidence that the E. multilocularis SERT and TPH are expressed in the nervous system of the protoscolex. Our results further suggest that the E. multilocularis SERT has a secondary role outside the nervous system that is essential for parasite integrity and survival. Since serotonin stimulated E. multilocularis metacestode development and proliferation, serotonin might also contribute to the formation and growth of the parasite in the liver.
Project description:This study aimed to find out the occurrence of Echinococcus multilocularis in foxes in Erzurum province, the highest endemic region for human alveolar echinococcosis in Turkey. The sedimentation and counting technique was used to reveal adult Echinococcus spp. in the intestines of foxes. One out of the 10 foxes was infected with E. multilocularis. The adult worms were analyzed morphologically and molecularly and were confirmed to be E. multilocularis by species-specific PCR. Pairwise comparisons between the 12S rRNA sequences of the E. multilocularis isolate from Erzurum and other E. multilocularis isolates showed 100% similarity of the Erzurum isolate with European isolates. With this study, the presence of E. multilocularis in a fox in Erzurum was confirmed by PCR, and molecular identification of E. multilocularis is reported for the first time in Turkey.