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Kaethner M, Preza M, Kaempfer T, Zumstein P, Tamponi C, Varcasia A, Hemphill A, Brehm K, Lundström-Stadelmann B. Establishment and application of unbiased in vitro drug screening assays for the identification of compounds against Echinococcus granulosus sensu stricto. PLoS Negl Trop Dis 2023; 17:e0011343. [PMID: 37540716 PMCID: PMC10431624 DOI: 10.1371/journal.pntd.0011343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 08/16/2023] [Accepted: 07/13/2023] [Indexed: 08/06/2023] Open
Abstract
Echinococcus multilocularis and E. granulosus s.l. are the causative agents of alveolar and cystic echinococcosis, respectively. Drug treatment options for these severe and neglected diseases are limited to benzimidazoles, which are not always efficacious, and adverse side effects are reported. Thus, novel and improved treatments are needed. In this study, the previously established platform for E. multilocularis in vitro drug assessment was adapted to E. granulosus s.s. In a first step, in vitro culture protocols for E. granulosus s.s. were established. This resulted in the generation of large amounts of E. granulosus s.s. metacestode vesicles as well as germinal layer (GL) cells. In vitro culture of these cells formed metacestode vesicles displaying structural characteristics of metacestode cysts generated in vivo. Next, drug susceptibilities of E. multilocularis and E. granulosus s.s. protoscoleces, metacestode vesicles and GL cells were comparatively assessed employing established assays including (i) metacestode vesicle damage marker release assay, (ii) metacestode vesicle viability assay, (iii) GL cell viability assay, and (iv) protoscolex motility assay. The standard drugs albendazole, buparvaquone, mefloquine, MMV665807, monepantel, niclosamide and nitazoxanide were included. MMV665807, niclosamide and nitazoxanide were active against the parasite in all four assays against both species. MMV665807 and monepantel were significantly more active against E. multilocularis metacestode vesicles, while albendazole and nitazoxanide were significantly more active against E. multilocularis GL cells. Albendazole displayed activity against E. multilocularis GL cells, but no effects were seen in albendazole-treated E. granulosus s.s. GL cells within five days. Treatment of protoscoleces with albendazole and monepantel had no impact on motility. Similar results were observed for both species with praziquantel and its enantiomers against protoscoleces. In conclusion, in vitro culture techniques and drug screening methods previously established for E. multilocularis were successfully implemented for E. granulosus s.s., allowing comparisons of drug efficacy between the two species. This study provides in vitro culture techniques for the reliable generation of E. granulosus s.s. metacestode vesicles and GL cell cultures and describes the validation of standardized in vitro drug screening methods for E. granulosus s.s.
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Affiliation(s)
- Marc Kaethner
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Switzerland
| | - Matías Preza
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland
| | - Tobias Kaempfer
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Switzerland
| | - Pascal Zumstein
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland
| | - Claudia Tamponi
- Department of Veterinary Medicine, University of Sassari, Italy
| | | | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland
| | - Klaus Brehm
- Institute of Hygiene and Microbiology, University of Würzburg, Germany
| | - Britta Lundström-Stadelmann
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
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Chaudhry S, Zurbriggen R, Preza M, Kämpfer T, Kaethner M, Memedovski R, Scorrano N, Hemphill A, Doggett JS, Lundström-Stadelmann B. Dual inhibition of the Echinococcus multilocularis energy metabolism. Front Vet Sci 2022; 9:981664. [PMID: 35990276 PMCID: PMC9388906 DOI: 10.3389/fvets.2022.981664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Alveolar echinococcosis is caused by the metacestode stage of the zoonotic parasite Echinococcus multilocularis. Current chemotherapeutic treatment options rely on benzimidazoles, which have limited curative capabilities and can cause severe side effects. Thus, novel treatment options are urgently needed. In search for novel targetable pathways we focused on the mitochondrial energy metabolism of E. multilocularis. The parasite relies hereby on two pathways: The classical oxidative phosphorylation including the electron transfer chain (ETC), and the anaerobic malate dismutation (MD). We screened 13 endochin-like quinolones (ELQs) in vitro for their activities against two isolates of E. multilocularis metacestodes and isolated germinal layer cells by the phosphoglucose isomerase (PGI) assay and the CellTiter Glo assay. For the five most active ELQs (ELQ-121, ELQ-136, ELQ-271, ELQ-400, and ELQ-437), EC50 values against metacestodes were assessed by PGI assay, and IC50 values against mammalian cells were measured by Alamar Blue assay. Further, the gene sequence of the proposed target, the mitochondrial cytochrome b, was analyzed. This allowed for a limited structure activity relationship study of ELQs against E. multilocularis, including analyses of the inhibition of the two functional sites of the cytochrome b. By applying the Seahorse XFp Extracellular Flux Analyzer, oxygen consumption assays showed that ELQ-400 inhibits the E. multilocularis cytochrome bc1 complex under normoxic conditions. When tested under anaerobic conditions, ELQ-400 was hardly active against E. multilocularis metacestodes. These results were confirmed by transmission electron microscopy. ELQ-400 treatment increased levels of parasite-released succinate, the final electron acceptor of the MD. This suggests that the parasite switched to MD for energy generation. Therefore, MD was inhibited with quinazoline, which did not induce damage to metacestodes under anaerobic conditions. However, it reduced the production of succinate compared to control treated parasites (i.e., inhibited the MD). The combination treatment with quinazoline strongly improved the activity of the bc1 inhibitor ELQ-400 against E. multilocularis metacestodes under anaerobic conditions. We conclude that simultaneous targeting of the ETC and the MD of E. multilocularis is a possible novel treatment approach for alveolar echinococcosis, and possibly also other foodborne diseases inflicted by platyhelminths, which cause substantial economic losses in livestock industry.
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Affiliation(s)
- Sheena Chaudhry
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Raphael Zurbriggen
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Matías Preza
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Tobias Kämpfer
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Marc Kaethner
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Roman Memedovski
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Nathalie Scorrano
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Joseph Stone Doggett
- Department of Infectious Diseases and Pathobiology, Oregon Health and Science University, Portland, OR, United States
- Department of Infectious Diseases and Pathobiology, Veterans Affairs Portland Health Care System, Portland, OR, United States
| | - Britta Lundström-Stadelmann
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- *Correspondence: Britta Lundström-Stadelmann
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Lundström-Stadelmann B, Rufener R, Hemphill A. Drug repurposing applied: Activity of the anti-malarial mefloquine against Echinococcus multilocularis. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2020; 13:121-129. [PMID: 32636148 PMCID: PMC7389337 DOI: 10.1016/j.ijpddr.2020.06.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 05/29/2020] [Accepted: 06/03/2020] [Indexed: 02/06/2023]
Abstract
The current chemotherapeutical treatment against alveolar echinococcosis relies exclusively on benzimidazoles, which are not parasiticidal and can induce severe toxicity. There are no alternative treatment options. To identify novel drugs with activity against Echinococcus multilocularis metacestodes, researchers have studied potentially interesting drug targets (e.g. the parasite's energy metabolism), and/or adopted drug repurposing approaches by undertaking whole organism screenings. We here focus on drug screening approaches, which utilize an in vitro screening cascade that includes assessment of the drug-induced physical damage of metacestodes, the impact on metacestode viability and the viability of isolated parasite stem cells, structure-activity relationship (SAR) analysis of compound derivatives, and the mode of action. Finally, once in vitro data are indicative for a therapeutic window, the efficacy of selected compounds is assessed in experimentally infected mice. Using this screening cascade, we found that the anti-malarial mefloquine was active against E. multilocularis metacestodes in vitro and in vivo. To shed more light into the mode of action of mefloquine, SAR analysis on mefloquine analogues was performed. E. multilocularis ferritin was identified as a mefloquine-binding protein, but its precise role as a drug target remains to be elucidated. In mice that were infected either intraperitoneally with metacestodes or orally with eggs, oral treatment with mefloquine led to a significant reduction of parasite growth compared to the standard treatment with albendazole. However, mefloquine was not acting parasiticidally. Assessment of mefloquine plasma concentrations in treated mice showed that levels were reached which are close to serum concentrations that are achieved in humans during long-term malaria prophylaxis. Mefloquine might be applied in human AE patients as a salvage treatment. Future studies should focus on other repurposed anti-infective compounds (MMV665807, niclosamide, atovaquone), which showed stronger in vitro activity against E. multilocularis than mefloquine.
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Affiliation(s)
- Britta Lundström-Stadelmann
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Längggassstrasse 122, 3012, Bern, Switzerland.
| | - Reto Rufener
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Längggassstrasse 122, 3012, Bern, Switzerland
| | - Andrew Hemphill
- Institute of Parasitology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Längggassstrasse 122, 3012, Bern, Switzerland
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Ritler D, Rufener R, Li JV, Kämpfer U, Müller J, Bühr C, Schürch S, Lundström-Stadelmann B. In vitro metabolomic footprint of the Echinococcus multilocularis metacestode. Sci Rep 2019; 9:19438. [PMID: 31857639 PMCID: PMC6923418 DOI: 10.1038/s41598-019-56073-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 12/04/2019] [Indexed: 12/17/2022] Open
Abstract
Alveolar echinococcosis (AE) is a zoonotic disease that is deadly if left untreated. AE is caused by the larval metacestode stage of the cestode Echinococcus multilocularis. Better knowledge on the host-parasite interface could yield novel targets for improvement of the treatment against AE. We analyzed culture media incubated with in vitro grown E. multilocularis metacestodes by 1H nuclear magnetic resonance spectroscopy to identify the unknown metabolic footprint of the parasite. Moreover, we quantitatively analyzed all amino acids, acetate, glucose, lactate, and succinate in time-course experiments using liquid chromatography and enzymatic assays. The E. multilocularis metacestodes consumed glucose and, surprisingly, threonine and produced succinate, acetate, and alanine as major fermentation products. The metabolic composition of vesicle fluid (VF) from in vitro grown E. multilocularis metacestodes was different from parasite-incubated culture medium with respect to the abundance, but not the spectrum, of metabolites, and some metabolites, in particular amino acids, accumulated in the VF. Overall, this study presents the first characterization of the in vitro metabolic footprint of E. multilocularis metacestodes and VF composition, and it provides the basis for analyses of potentially targetable pathways for future drug development.
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Affiliation(s)
- Dominic Ritler
- Institute of Parasitology, Department of Infectious Disease and Pathobiology, Vetsuisse Bern, University of Bern, Bern, Switzerland
| | - Reto Rufener
- Institute of Parasitology, Department of Infectious Disease and Pathobiology, Vetsuisse Bern, University of Bern, Bern, Switzerland
| | - Jia V Li
- Division of Systems and Digestive Medicine, Department of Surgery & Cancer, Imperial College London, London, United Kingdom
| | - Urs Kämpfer
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Joachim Müller
- Institute of Parasitology, Department of Infectious Disease and Pathobiology, Vetsuisse Bern, University of Bern, Bern, Switzerland
| | - Claudia Bühr
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Stefan Schürch
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Britta Lundström-Stadelmann
- Institute of Parasitology, Department of Infectious Disease and Pathobiology, Vetsuisse Bern, University of Bern, Bern, Switzerland.
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Rufener R, Dick L, D'Ascoli L, Ritler D, Hizem A, Wells TNC, Hemphill A, Lundström-Stadelmann B. Repurposing of an old drug: In vitro and in vivo efficacies of buparvaquone against Echinococcus multilocularis. Int J Parasitol Drugs Drug Resist 2018; 8:440-450. [PMID: 30396011 PMCID: PMC6216040 DOI: 10.1016/j.ijpddr.2018.10.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/29/2018] [Accepted: 10/29/2018] [Indexed: 12/12/2022]
Abstract
The metacestode stage of the fox tapeworm Echinococcus multilocularis causes the lethal disease alveolar echinococcosis. Current chemotherapeutic treatment options are based on benzimidazoles (albendazole and mebendazole), which are insufficient and hence alternative drugs are needed. In this study, we screened the 400 compounds of the Medicines for Malaria Venture (MMV) Pathogen Box against E. multilocularis metacestodes. For the screen, we employed the phosphoglucose isomerase (PGI) assay which assesses drug-induced damage on metacestodes, and identified ten new compounds with activity against the parasite. The anti-theilerial drug MMV689480 (buparvaquone) and MMV671636 (ELQ-400) were the most promising compounds, with an IC50 of 2.87 μM and 0.02 μM respectively against in vitro cultured E. multilocularis metacestodes. Both drugs suggested a therapeutic window based on their cytotoxicity against mammalian cells. Transmission electron microscopy revealed that treatment with buparvaquone impaired parasite mitochondria early on and additional tests showed that buparvaquone had a reduced activity under anaerobic conditions. Furthermore, we established a system to assess mitochondrial respiration in isolated E. multilocularis cells in real time using the Seahorse XFp Analyzer and demonstrated inhibition of the cytochrome bc1 complex by buparvaquone. Mice with secondary alveolar echinococcosis were treated with buparvaquone (100 mg/kg per dose, three doses per week, four weeks of treatment), but the drug failed to reduce the parasite burden in vivo. Future studies will reveal whether improved formulations of buparvaquone could increase its effectivity.
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Affiliation(s)
- Reto Rufener
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012, Bern, Switzerland
| | - Luca Dick
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012, Bern, Switzerland
| | - Laura D'Ascoli
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012, Bern, Switzerland
| | - Dominic Ritler
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012, Bern, Switzerland
| | - Amani Hizem
- Laboratory of Medical and Molecular Parasitology-Mycology, LR 12ES08, Department of Clinical Biology B, Faculty of Pharmacy of Monastir, University of Monastir, Monastir, 5000, Tunisia
| | - Timothy N C Wells
- Medicines for Malaria Venture (MMV), Route de Pré-Bois 20, 1215, Geneva, Switzerland
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012, Bern, Switzerland
| | - Britta Lundström-Stadelmann
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012, Bern, Switzerland.
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Abstract
Cytochemical staining with diaminobenzidine (DAB) has been used to locate cytochrome oxidase activity in mitochondria from major tissues of three intestinal parasitic nematodes, Nippostrongylus brasiliensis, Haemonchus contortus and Ascaridia galli. Deposition of DAB reaction product was uniform and relatively intense in mitochondria from all tissues studied in N. brasiliensis. However, mitochondria from different tissues of H. contortus and A. galli varied considerably in their cytochemical staining, decreasing in the order hypodermis < muscle < gut < reproductive tissue. Mitochondria in gut and reproductive tissue of A. galli possessed little or no cytochrome oxidase activity. These results are compatible with respect to oxygen availability and the extent and localization of the mammalian-type aerobic mitochondrial electron transport pathway in intestinal parasitic nematodes.
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Corbett JR, Goose J. A possible biochemical mode of action of the fasciolicides nitroxynil, hexachlorophene and oxyclozanide. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/ps.2780020307] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
A variety of anti-mitochondrial drugs that had previously been found to inhibit the growth of the malarial parasite Plasmodium falciparum were tested on Babesia bovis in vitro. Several of these drugs were found to be non-toxic towards B. bovis. However, those drugs that were found to inhibit babesial growth included compounds (shown in parentheses) that have the following putative mitochondrial targets in the parasite: ATP synthetase complex (rhodamine 123, oligomycin, Janus Green); ATP-ADP translocase (bongkrekic acid); electron transport (rotenone, n-heptyl-4-hydroxyquinoline-N-oxide (HQNO), antimycin A); ubiquinone (CoQ) function (BW58C, menoctone); protein synthesis (tetracycline); and the proton pump (CCCP). We have also investigated the effects of some of these drugs on pyrimidine biosynthesis de novo by following the incorporation of [14C]bicarbonate into pyrimidine nucleotides and into the pyrimidine moieties of nucleic acids. The ubiquinone analogues BW58C and menoctone inhibited this pathway in the nM-microM range of concentrations. Inhibitors of electron transport (antimycin A and oligomycin) and an uncoupler (CCCP) were also effective inhibitors of pyrimidine biosynthesis de novo. We conclude that B. bovis has a functional mitochondrion that contributes significantly to pyrimidine biosynthesis de novo and to the overall energy metabolism of the parasite.
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Affiliation(s)
- M M Gozar
- School of Biochemistry and Molecular Genetics, University of New South Wales, Kensington, Australia
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Petronijevic T, Rogers WP. The physiology of infection with nematodes: the role of intracellular pH in the development of the early parasitic stage. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. A, COMPARATIVE PHYSIOLOGY 1987; 88:207-12. [PMID: 2890466 DOI: 10.1016/0300-9629(87)90471-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
1. H2CO3, the host's signal which induced (less than 25 min) the Ca2+-dependent development of the first parasitic stage of Haemonchus contortus, produced a diphasic change in the pHi (less than 30 min), measured with 5,5-dimethyl-2,4-oxazolidinedione, in the infective stage. The intensity of the diphasic change was related to the [H2CO3] and so to the efficiency of the stimulus for development. 2. MES and HEPES buffers induced a rapid rise in pHi of infective stages in step with pHo. Ortho-and pyrophosphate induced greater changes in pHi. Such buffers did not initiate development. 3. These and other results suggest that the stimulus for development, H2CO3, induced an energy-dependent Ca2+/H+ exchange mediated by mitochondria of the infective stage, which initiated development of the parasitic stage.
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Affiliation(s)
- T Petronijevic
- Department of Plant Physiology, Waite Agricultural Research Institute, South Australia
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Abstract
Aerobic respiratory pathways have been compared in adult parasitic nematodes, including Trichostrongylus colubriformis, Nippostrongylus brasiliensis, Ostertagia ostertagi, Cooperia oncophora, Haemonchus contortus, Oesophagostomum venulosum, Chabertia ovina, Dictyocaulus filaria, Dictyocaulus viviparus, and Ascaridia galli. Respiration was measured in both whole worm or tissue homogenates and isolated mitochondrial fractions, and delineated into the mammalian type or alternative respiratory pathways on the basis of their inhibition by antimycin A. The alternative, antimycin A-insensitive respiratory pathway was of comparable activity in all parasitic nematodes studied, irrespective of the body diameter or habitat of the worm. The mammalian-type, antimycin A-sensitive respiratory pathway showed variations; the extent of this pathway correlated with both the body diameter and habitat of the worm, being greater in thinner worms and those worms whose habitat is supposedly more aerobic.
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Mendis A, Evans A. First evidence for the occurrence of cytochrome-o in a free-living nematode. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/0305-0491(84)90126-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Threadgold LT, Hanna B. Development of an invitro technique for cytological investigations of slices of fasciola hepatica: evaluation by physiological criteria. Int J Parasitol 1975; 5:333-7. [PMID: 1126787 DOI: 10.1016/0020-7519(75)90081-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Salminen K. Succinate dehydrogenase and cytochrome oxidase in adult and plerocercoid Diphyllobothrium latum. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1974; 49:87-92. [PMID: 4370415 DOI: 10.1016/0305-0491(74)90226-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Metzger H, Düwel D. Investigations of metabolism in the liver fluke (Fasciola hepatica) as an aid to the development of new anthelmintics. ACTA ACUST UNITED AC 1973. [DOI: 10.1016/0020-711x(73)90005-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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