title: Hemozoin is a product of heme detoxification in the gut of the most medically important species of the family Opisthorchiidae.
abstract: Many species of trematodes such as Schistosoma spp., Fasciola hepatica and Echinostoma trivolvis are blood-feeding parasites. Nevertheless, there is no consensus on the feeding habits of the family Opisthorchiidae (Opisthorchis felineus, Opisthorchis viverrini and Clonorchis sinensis). Previously, histological studies of O. felineus and C. sinensis revealed some dark stained material in their gut lumen. In this study we conducted a comprehensive analysis of the gut contents of three members of the family Opisthorchiidae (O. felineus, O. viverrini and C. sinensis). Using transmission electron microscopy, we demonstrated for the first known time the presence of disintegrating blood cells in the gut of O. felineus as well as electron-dense crystals in the gut of O. felineus and C. sinensis. Electron energy loss spectroscopy revealed iron atoms in these crystals, and mass spectrometry of the purified pigment demonstrated the presence of heme. Fourier-transform infrared spectroscopy identified the signature peaks of the common iron-carboxylate bond characteristic in crystals isolated from O. felineus and C. sinensis. Scanning electron microscopy showed layered ovoid crystals of various sizes from 50 nm to 2 μm. Morphological, chemical and paramagnetic properties of these crystals were similar to those of hemozoin from Schistosoma mansoni. Crystal formation occurs on the surface of lipid droplets in O. felineus and C. sinensis guts. Our results suggest that the diet of O. felineus and C. sinensis includes blood. Detoxification of the free heme produced during the digestion proceeds via formation of insoluble crystals that contain iron and heme dimers, i.e. crystals of hemozoin. Furthermore, we believe that biocrystallisation of hemozoin takes place on the surface of the lipid droplets, similar to S. mansoni. Hemozoin was not detected in the closely related species O. viverrini.
authors.affiliation: Federal State Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, 10 Lavrentiev Ave., Novosibirsk 630090, Russia. Electronic address: lvovamaria@bionet.nsc.ru.
authors.forename: Maria
authors.initials: M
authors.lastname: Lvova
authors.affiliation: Federal State Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, 10 Lavrentiev Ave., Novosibirsk 630090, Russia.
authors.forename: Mariya
authors.initials: M
authors.lastname: Zhukova
authors.affiliation: Federal State Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, 10 Lavrentiev Ave., Novosibirsk 630090, Russia.
authors.forename: Elena
authors.initials: E
authors.lastname: Kiseleva
authors.affiliation: Center for Proteomics and Metabolomics, Leiden University Medical Center, Zone P, Albinusdreef 2, 2333 ZA Leiden, The Netherlands; Department of Chemistry, Tomsk State University, 2 Moskovsky Trakt, Tomsk 634050, Russia.
authors.forename: Oleg
authors.initials: O
authors.lastname: Mayboroda
authors.affiliation: Center for Proteomics and Metabolomics, Leiden University Medical Center, Zone P, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Hensbergen
authors.affiliation: Federal State Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, 10 Lavrentiev Ave., Novosibirsk 630090, Russia.
authors.forename: Elena
authors.initials: E
authors.lastname: Kizilova
authors.affiliation: Federal State Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, 10 Lavrentiev Ave., Novosibirsk 630090, Russia.
authors.forename: Anna
authors.initials: A
authors.lastname: Ogienko
authors.affiliation: Institute of Biology and Soil Science, Far-Eastern Branch of Russian Academy of Sciences, Stoletiya St. 159, Vladivostok 690022, Russia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Besprozvannykh
authors.affiliation: Department of Pathology, Faculty of Medicine, Khon Kaen University, 123 Mittraparp Highway, Muang District, Khon Kaen 40002, Thailand.
authors.forename: Banchob
authors.initials: B
authors.lastname: Sripa
authors.affiliation: Federal State Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, 10 Lavrentiev Ave., Novosibirsk 630090, Russia.
authors.forename: Alexey
authors.initials: A
authors.lastname: Katokhin
authors.affiliation: Federal State Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, 10 Lavrentiev Ave., Novosibirsk 630090, Russia; Laboratory of Pharmacokinetic and Drugs Metabolism, Institute of Molecular Biology and Biophysics, Siberian Branch of Russian Academy of Medical Sciences, Timakov St. 2/12, 630117 Novosibirsk, Russia.
authors.forename: Viatcheslav
authors.initials: V
authors.lastname: Mordvinov
mesh_terms: D000818:Animals; D003003:Clonorchiasis / Q000469:parasitology / Q000662:veterinary*; D003004:Clonorchis sinensis / Q000378:metabolism*; D003530:Cyprinidae / Q000469:parasitology; D005393:Fish Diseases / Q000469:parasitology; D041981:Gastrointestinal Tract / Q000378:metabolism; D006418:Heme / Q000378:metabolism*; D006420:Hemeproteins / Q000737:chemistry / Q000378:metabolism*; D009889:Opisthorchiasis / Q000469:parasitology / Q000662:veterinary*; D009891:Opisthorchis / Q000378:metabolism*
chemical_list: D006420:Hemeproteins; C020753:hemozoin; D006418:Heme
keywords: Blood-feeding parasite; Clonorchis sinensis; Hemozoin; Lipid droplets; Opisthorchis felineus; Opisthorchis viverrini