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Crego-Vicente B, Fernández-Soto P, Febrer-Sendra B, García-Bernalt Diego J, Boissier J, Angora EK, Oleaga A, Muro A. Application of a Genus-Specific LAMP Assay for Schistosome Species to Detect Schistosoma haematobium x Schistosoma bovis Hybrids. J Clin Med 2021; 10:jcm10061308. [PMID: 33810080 PMCID: PMC8004683 DOI: 10.3390/jcm10061308] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/08/2021] [Accepted: 03/18/2021] [Indexed: 02/07/2023] Open
Abstract
Schistosomiasis is a disease of great medical and veterinary importance in tropical and subtropical regions caused by different species of parasitic flatworms of the genus Schistosoma. The emergence of natural hybrids of schistosomes indicate the risk of possible infection to humans and their zoonotic potential, specifically for Schistosoma haematobium and S. bovis. Hybrid schistosomes have the potential to replace existing species, generate new resistances, pathologies and extending host ranges. Hybrids may also confuse the serological, molecular and parasitological diagnosis. Currently, LAMP technology based on detection of nucleic acids is used for detection of many agents, including schistosomes. Here, we evaluate our previously developed species-specific LAMP assays for S. haematobium, S. mansoni, S. bovis and also the genus-specific LAMP for the simultaneous detection of several Schistosoma species against both DNA from pure and, for the first time, S. haematobium x S. bovis hybrids. Proper operation was evaluated with DNA from hybrid schistosomes and with human urine samples artificially contaminated with parasites' DNA. LAMP was performed with and without prior DNA extraction. The genus-specific LAMP properly amplified pure Schistosoma species and different S. haematobium-S. bovis hybrids with different sensitivity. The Schistosoma spp.-LAMP method is potentially adaptable for field diagnosis and disease surveillance in schistosomiasis endemic areas where human infections by schistosome hybrids are increasingly common.
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Affiliation(s)
- Beatriz Crego-Vicente
- Infectious and Tropical Diseases Research Group (e-INTRO), Research Centre for Tropical Diseases at the University of Salamanca (IBSAL-CIETUS), Biomedical Research Institute of Salamanca, Faculty of Pharmacy, University of Salamanca, 37007 Salamanca, Spain; (B.C.-V.); (B.F.-S.); (J.G.-B.D.)
| | - Pedro Fernández-Soto
- Infectious and Tropical Diseases Research Group (e-INTRO), Research Centre for Tropical Diseases at the University of Salamanca (IBSAL-CIETUS), Biomedical Research Institute of Salamanca, Faculty of Pharmacy, University of Salamanca, 37007 Salamanca, Spain; (B.C.-V.); (B.F.-S.); (J.G.-B.D.)
- Correspondence: (P.F.-S.); (A.M.); Tel.: +34-677596173 (P.F.-S.); +34-677596155 (A.M.)
| | - Begoña Febrer-Sendra
- Infectious and Tropical Diseases Research Group (e-INTRO), Research Centre for Tropical Diseases at the University of Salamanca (IBSAL-CIETUS), Biomedical Research Institute of Salamanca, Faculty of Pharmacy, University of Salamanca, 37007 Salamanca, Spain; (B.C.-V.); (B.F.-S.); (J.G.-B.D.)
| | - Juan García-Bernalt Diego
- Infectious and Tropical Diseases Research Group (e-INTRO), Research Centre for Tropical Diseases at the University of Salamanca (IBSAL-CIETUS), Biomedical Research Institute of Salamanca, Faculty of Pharmacy, University of Salamanca, 37007 Salamanca, Spain; (B.C.-V.); (B.F.-S.); (J.G.-B.D.)
| | - Jérôme Boissier
- IHPE, Université Montpellier, CNRS, Ifremer, Université Perpignan Via Domitia, 66100 Perpignan, France;
| | - Etienne K. Angora
- Swiss Tropical and Public Health Institute, P.O. Box CH-4002 Basel, Switzerland;
- Department of Public Health, University of Basel, P.O. Box CH-4003 Basel, Switzerland
- Unité de Formation et de Recherche Sciences Pharmaceutiques et Biologiques, Université Félix Houphouët-Boigny, Abidjan BPV 34, Côte d’Ivoire
| | - Ana Oleaga
- Parasitology Laboratory, Institute of Natural Resources and Agrobiology (IRNASA, CSIC), Cordel de Merinas 40-52, 37008 Salamanca, Spain;
| | - Antonio Muro
- Infectious and Tropical Diseases Research Group (e-INTRO), Research Centre for Tropical Diseases at the University of Salamanca (IBSAL-CIETUS), Biomedical Research Institute of Salamanca, Faculty of Pharmacy, University of Salamanca, 37007 Salamanca, Spain; (B.C.-V.); (B.F.-S.); (J.G.-B.D.)
- Correspondence: (P.F.-S.); (A.M.); Tel.: +34-677596173 (P.F.-S.); +34-677596155 (A.M.)
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Morphological and Molecular Identification of Paramphistomum epiclitum from Buffaloes in Pakistan. Acta Parasitol 2020; 65:225-236. [PMID: 31848844 DOI: 10.2478/s11686-019-00155-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 12/03/2019] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Little is known about the genetic and morphological characters of Paramphistomum epiclitum. For the first time in Pakistan, adult flukes were morphologically characterized and the sequence variation in the nuclear ribosomal DNA (rDNA) region, including the first internal transcribed spacers (ITS1) and the 5.8S gene of the Paramphistomum epiclitum were studied. METHODS Adult amphistomes were examined by light microscopy and sequences of ITS1 and 5.88S rDNA genes were obtained. RESULTS Twenty adult flukes were measured, 13.17 ± 1.19 mm in length and 5.28 ± 1.34 mm in width. Seventeen adult flukes were sequenced and high sequence variability was observed in 5' end of ITS1 region. The 5.8S and 3' end of ITS1 sequences had 100% identity among the samples. A comparative analysis revealed that different types and numbers of repeats were found within each ITS1 region. The 3' end of ITS1 region from P. epiclitum showed 98% homology with P. cervi from China and formed a subclade with genetic distance of 0.1663. The 5.8S gene showed 100% identity within Paramphistomidae family and formed a sub-clade with P. epiclitum, P. leydeni, P. cervi and Cotylophoron cotylophorum species isolated from China, India and Uruguay. CONCLUSION This work provides new information on morphological identity and genetics of P. epiclitum from Pakistan.
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Tatonova YV, Chelomina GN, Nguyen HM. Inter-individual and intragenomic variations in the ITS region of Clonorchis sinensis (Trematoda: Opisthorchiidae) from Russia and Vietnam. INFECTION GENETICS AND EVOLUTION 2017; 55:350-357. [DOI: 10.1016/j.meegid.2017.10.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 10/06/2017] [Accepted: 10/06/2017] [Indexed: 01/18/2023]
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Characterization of the complete nuclear ribosomal DNA sequences of Eurytrema pancreaticum. J Helminthol 2017; 92:484-490. [DOI: 10.1017/s0022149x17000554] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractEurytrema pancreaticum is one of the most common trematodes of cattle and sheep, and also infects humans occasionally, causing great economic losses and medical costs. In this study, the sequences of the complete nuclear ribosomal DNA (rDNA) repeat units of five E. pancreaticum individuals were determined for the first time. They were 8306–8310 bp in length, including the small subunit (18S) rDNA, internal transcribed spacer 1 (ITS1), 5.8S rDNA, internal transcribed spacer 2 (ITS2), large subunit (28S) rDNA and intergenic spacer (IGS). There were no length variations in any of the investigated 18S (1996 bp), ITS1 (1103 bp), 5.8S (160 bp), ITS2 (231 bp) or 28S (3669 bp) rDNA sequences, whereas the IGS rDNA sequences of E. pancreaticum had a 4-bp length variation, ranging from 1147 to 1151 bp. The intraspecific variations within E. pancreaticum were 0–0.2% for 18S rDNA, 0–0.5% for ITS1, 0% for 5.8S rDNA and ITS2, 0–0.2% for 28S rDNA and 2.9–20.2% for IGS. There were nine types of repeat sequences in ITS1, two types in 28S rDNA, but none in IGS. A phylogenetic analysis based on the 18S rDNA sequences classified E. pancreaticum in the family Dicrocoeliidae of Plagiorchiata, closely related to the suborder Opisthorchiata. These results provide useful information for the further study of Dicrocoeliidae trematodes.
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Molecular characterization of Stictodora tridactyla (Trematoda: Heterophyidae) from Kuwait Bay using rDNA ITS and mtCO1. Parasitol Res 2015; 114:4259-66. [PMID: 26268569 DOI: 10.1007/s00436-015-4665-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 08/04/2015] [Indexed: 10/23/2022]
Abstract
Stictodora tridactyla is an intestinal fluke in the family Heterophyidae that parasitizes shorebirds and mammals, including humans. Its metacercarial cyst stage was reported in the Arabian killifish, Aphanius dispar, at Kuwait Bay. In the present study, Cerithidea cingulata was found to serve as the first intermediate host of S. tridactyla. In order to establish the snail-fish link in the life cycle of S. tridactyla, complete sequences of ribosomal DNA internal transcribed spacer region 1 and 2 (rDNA ITS1 and ITS2) and partial sequence of cytochrome oxidase subunit 1 were obtained for metacercarial cysts isolated from the fish A. dispar and rediae isolated from the snail C. cingulata. Sequence alignment demonstrated that these larval stages belong to the same heterophyid species, S. tridactyla. Phylogenetic analysis based on rDNA ITS1, ITS2, and mtCO1 confirmed the position of S. tridactyla within the Heterophyidae and found it to cluster with Haplorchis spp. The present study represents the first molecular study correlating the larval stages of S. tridactyla using rDNA ITS1, ITS2, and mtCO1 and examining the phylogenetic relationships of S. tridactyla with different heterophyid species.
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Li J, Zhao GH, Lin R, Blair D, Sugiyama H, Zhu XQ. Rapid detection and identification of four major Schistosoma species by high-resolution melt (HRM) analysis. Parasitol Res 2015; 114:4225-32. [PMID: 26253799 DOI: 10.1007/s00436-015-4660-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 07/30/2015] [Indexed: 11/26/2022]
Abstract
Schistosomiasis, caused by blood flukes belonging to several species of the genus Schistosoma, is a serious and widespread parasitic disease. Accurate and rapid differentiation of these etiological agents of animal and human schistosomiasis to species level can be difficult. We report a real-time PCR assay coupled with a high-resolution melt (HRM) assay targeting a portion of the nuclear 18S rDNA to detect, identify, and distinguish between four major blood fluke species (Schistosoma japonicum, Schistosoma mansoni, Schistosoma haematobium, and Schistosoma mekongi). Using this system, the Schistosoma spp. was accurately identified and could also be distinguished from all other trematode species with which they were compared. As little as 10(-5) ng genomic DNA from a Schistosoma sp. could be detected. This process is inexpensive, easy, and can be completed within 3 h. Examination of 21 representative Schistosoma samples from 15 geographical localities in seven endemic countries validated the value of the HRM detection assay and proved its reliability. The melting curves were characterized by peaks of 83.65 °C for S. japonicum and S. mekongi, 85.65 °C for S. mansoni, and 85.85 °C for S. haematobium. The present study developed a real-time PCR coupled with HRM analysis assay for detection and differential identification of S. mansoni, S. haematobium, S. japonicum, and S. mekongi. This method is rapid, sensitive, and inexpensive. It has important implications for epidemiological studies of Schistosoma.
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Affiliation(s)
- Juan Li
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, 730046, People's Republic of China
- Institute of Animal Health, Guangdong Academy Agricultural Sciences, Guangzhou, Guangdong Province, 510640, People's Republic of China
| | - Guang-Hui Zhao
- College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi Province, 712100, People's Republic of China
| | - RuiQing Lin
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province, 510642, People's Republic of China
| | - David Blair
- School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, 4811, Australia
| | - Hiromu Sugiyama
- Department of Parasitology, National Institute of Infectious Diseases, 113-8421, Tokyo, Japan
| | - Xing-Quan Zhu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, 730046, People's Republic of China.
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New multiplex PCR method for the simultaneous diagnosis of the three known species of equine tapeworm. Vet Parasitol 2014; 207:56-63. [PMID: 25498328 DOI: 10.1016/j.vetpar.2014.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Revised: 10/30/2014] [Accepted: 11/05/2014] [Indexed: 11/23/2022]
Abstract
Although several techniques exist for the detection of equine tapeworms in serum and feces, the differential diagnosis of tapeworm infection is usually based on postmortem findings and the morphological identification of eggs in feces. In this study, a multiplex polymerase chain reaction (PCR)-based method for the simultaneuos detection of Anoplocephala magna, Anoplocephala perfoliata and Anoplocephaloides mamillana has been developed and validated. The method simultaneously amplifies hypervariable SSUrRNA gene regions in the three tapeworm species in a single reaction using three pairs of primers, which exclusively amplify the internal transcribed spacer 2 (ITS-2) in each target gene. The method was tested on three types of sample: (a) 1/10, 1/100, 1/500, 1/1000, 1/2000 and 1/5000 dilutions of 70 ng of genomic DNA of the three tapeworm species, (b) DNA extracted from negative aliquots of sediments of negative control fecal samples spiked with 500, 200, 100, 50 and 10 eggs (only for A. magna and A. perfoliata; no A. mamillana eggs available) and (c) DNA extracted from 80, 50, 40, 30, 10 and 1 egg per 2 μl of PCR reaction mix (only for A. magna and A. perfoliata; no A. mamillana eggs available). No amplification was observed against the DNA of Gasterophilus intestinalis, Parascaris equorum and Strongylus vulgaris. The multiplex PCR method emerged as specific for the three tapeworms and was able to identify as few as 50 eggs per fecal sample and as little as 0.7 ng of control genomic DNA obtained from the three species. The method proposed is able to differentiate infections caused by the two most frequent species A. magna or A. perfoliata when the eggs are present in feces and is also able to detect mixed infections by the three cestode species.
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Characterization of the complete nuclear ribosomal DNA sequences of Paramphistomum cervi. ScientificWorldJournal 2014; 2014:751907. [PMID: 25140347 PMCID: PMC4129167 DOI: 10.1155/2014/751907] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 06/16/2014] [Indexed: 11/29/2022] Open
Abstract
Sequences of the complete nuclear ribosomal DNA (rDNA) gene from five individual Paramphistomum cervi were determined for the first time. The five complete rDNA sequences, which included the 18S rDNA, the internal transcribed spacer 1 (ITS1), the 5.8S rDNA, the internal transcribed spacer 2 (ITS2), the 28S rDNA, and the intergenic spacer (IGS) regions, had a length range of 8,493–10,221 bp. The lengths of the investigated 18S, ITS1, 5.8S, ITS2, and 28S rDNA sequences, which were 1,994 bp, 1,293 bp, 157 bp, 286 bp, and 4,186 bp, respectively, did not vary. However, the IGS rDNA sequences had a length range of 577–2,305 bp. The 5.8S and ITS-2 rDNA sequences had 100% identity among the five investigated samples, while the identities among the IGS had a range of 53.7–99.8%. A comparative analysis revealed that different types and numbers of repeats were found within each ITS1 and IGS region, which may be related to the length polymorphism of IGS. The phylogenetic position of P. cervi in Paramphistomatidae was analyzed based on the 18S rDNA sequences. These results will aid in studying the intra- and interspecific variation of the Paramphistomatidae and the systematics and phylogenetics of Digenea.
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Razo-Mendivil U, Pérez-Ponce de León G, Rubio-Godoy M. Integrative taxonomy identifies a new species of Phyllodistomum (Digenea: Gorgoderidae) from the twospot livebearer, Heterandria bimaculata (Teleostei: Poeciliidae), in Central Veracruz, Mexico. Parasitol Res 2014; 112:4137-50. [PMID: 24022129 DOI: 10.1007/s00436-013-3605-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 08/25/2013] [Indexed: 11/29/2022]
Abstract
Phyllodistomum inecoli n. sp. is described from the twospot livebearer, Heterandria bimaculata (Teleostei: Poeciliidae), collected in the Río La Antigua basin, Veracruz, Mexico. The new species is described and characterised by using a combination of morphology, scanning electron microscopy, and sequences of nuclear and mitochondrial genes. Diagnostic characters of the new species of Phyllodistomum include a genital pore opening at the level of the caecal bifurcation; oval vitellarium, situated just posterior to the ventral sucker and not extended laterally and anterior extracaecal uterine loops variable in extension (reaching the anterior, median or posterior margin of the ventral sucker). P. inecoli n. sp. most closely resembles P. brevicecum, a species described as a parasite of the central mudminnow, Umbra limi, in other parts of North America; however, the genital pore in P. brevicecum is situated between the caecal bifurcation and the ventral sucker, the ovary is larger, the vitellarium is lobed and extended laterally and the anterior portion of the uterus extends to the posterior margin of the ventral sucker. Comparison of about 1,500–2,200 nucleotides of cox1 and 28S rDNA and ITS1 strongly supports the status of P. inecoli as a new species. Bayesian inference analysis of combined datasets of 28S rDNA and cox1 sequences showed that P. inecoli n. sp. and the other species found in freshwater fishes of Mexico, including the species complex of P. lacustri, are not sister species. Phylogenetic analysis based on 28S rDNA sequences of several gorgoderid taxa revealed the close relationship of P. inecoli n. sp. with several species of Phyllodistomum, Gorgodera and Gorgoderina with cystocercous cercariae developing in sphaeriid bivalves. Dot-plot analysis of ITS1 sequences of P. inecoli n. sp. revealed the presence of eight repetitive elements with different length, which together represent almost half the length of ITS1.
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Tatonova YV, Chelomina GN, Besprosvannykh VV. Genetic diversity of nuclear ITS1–5.8S–ITS2 rDNA sequence in Clonorchis sinensis Cobbold, 1875 (Trematoda: Opisthorchidae) from the Russian Far East. Parasitol Int 2012; 61:664-74. [DOI: 10.1016/j.parint.2012.07.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 07/05/2012] [Accepted: 07/09/2012] [Indexed: 10/28/2022]
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Li J, Zhao GH, Zhou DH, Sugiyama H, Nisbet AJ, Li XY, Zou FC, Li HL, Ai L, Zhu XQ. Retrotransposon-microsatellite amplified polymorphism, an electrophoretic approach for studying genetic variability among Schistosoma japonicum geographical isolates. Electrophoresis 2012; 33:2859-66. [PMID: 23019103 DOI: 10.1002/elps.201200110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In the present study, retrotransposon-microsatellite amplified polymorphism (REMAP) was used to examine genetic variability among Schistosoma japonicum isolates from different endemic provinces in mainland China, using S. japonicum from Japan and the Philippines for comparison. Of the 50 primer combinations screened, eight produced highly reproducible REMAP fragments. Using these primers, 190 distinct DNA fragments were generated in total, of which 147 (77.37%) were polymorphic, indicating considerable genetic variation among the 43 S. japonicum isolates examined. The percentage of polymorphic bands (PPB) among S. japonicum isolates from mainland China, Japan, and the Philippines was 77.37%; PPB values of 18.42% and 53.68% were found among isolates from southwestern (SW) China and the lower Yangtze/Zhejiang province in eastern (E) China, respectively. Based on REMAP profiles, unweighted pair-group method with arithmetic averages (UPGMA) dendrogram analysis revealed that all of the S. japonicum samples grouped into three distinct clusters: parasites from mainland China, Japan, and the Philippines were clustered in each individual clade. Within the mainland China cluster, SW China isolates (from Sichuan and Yunnan provinces) grouped together, whereas worms from E China (Zhejiang, Anhui, Jiangxi, Jiangsu, Hunan, and Hubei provinces) grouped together. These results demonstrated that the REMAP marker system provides a reliable electrophoretic technique for studying genetic diversity and population structures of S. japonicum isolates from mainland China, and could be applied to other pathogens of human and animal health significance.
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Affiliation(s)
- Juan Li
- Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, People's Republic of China
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Al-Kandari WY, Al-Bustan SA, Alnaqeeb M. Ribosomal DNA Sequence Characterization of Maritrema CF. Eroliae Yamaguti, 1939 (Digenea: Microphallidae) and Its Life Cycle. J Parasitol 2011; 97:1067-74. [DOI: 10.1645/ge-2869.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Li J, Zhao GH, Chen F, Song HQ, Zhu XQ, Zhao GH, Li J, Chen F, Lin RQ, Weng YB, Mahmoud MS, Zou FC. A cleaved amplified polymorphic sequence (CAPS) method for the identification of geographical isolates of Schistosoma japonicum in China. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2011; 105:531-6. [PMID: 22185948 PMCID: PMC4100313 DOI: 10.1179/2047773211y.0000000004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 10/21/2011] [Accepted: 10/24/2011] [Indexed: 10/31/2022]
Affiliation(s)
- J Li
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, CAAS, Lanzhou 730046, China
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Abstract
SUMMARYSystematics involves resolving both the taxonomy and phylogenetic placement of organisms. We review the advantages and disadvantages of the two kinds of information commonly used for such inferences – morphological and molecular data – as applied to the systematics of metazoan parasites generally, with special attention to the malaria parasites. The problems that potentially confound the use of morphology in parasites include challenges to consistent specimen preservation, plasticity of features depending on hosts or other environmental factors, and morphological convergence. Molecular characters such as DNA sequences present an alternative data source and are particularly useful when not all the parasite's life stages are present or when parasitaemia is low. Nonetheless, molecular data can bring challenges that include troublesome DNA isolation, paralogous gene copies, difficulty in developing molecular markers, and preferential amplification in mixed species infections. Given the differential benefits and shortcomings of both molecular and morphological characters, both should be implemented in parasite taxonomy and phylogenetics.
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Li J, Zhao GH, Li XY, Chen F, Chen JB, Zou FC, Yang JF, Lin RQ, Weng YB, Zhu XQ. IRAP: An efficient retrotransposon-based electrophoretic technique for studying genetic variability among geographical isolates of Schistosoma japonicum. Electrophoresis 2011; 32:1473-9. [PMID: 21626522 DOI: 10.1002/elps.201100044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 03/04/2011] [Accepted: 03/04/2011] [Indexed: 11/12/2022]
Abstract
In the present study, a inter-retrotransposon-amplified polymorphism (IRAP) technique, based on retrotransposons, was used to examine genetic variability among Schistosoma japonicum isolates from different provinces in mainland China. Of the 15 primers screened, 5 produced highly reproducible IRAP patterns. Using these primers, 54 discernible DNA fragments were generated with 40 (74.07%) being polymorphic, indicating considerable genetic variation among the examined S. japonicum isolates. The primer LTR-11 was found to be able to differentiate male and female parasites, producing one constant specific band for female S. japonicum isolates. The percentages of polymorphic bands (PPB) among all parasites, among isolates from mountainous provinces and among those from the lake/marshland areas were 74.07, 48.15, and 66.67%, respectively. UPGMA analysis revealed that the IRAP profiles could group S. japonicum isolates in mainland China into two clades (mountainous and lake/marshland types), and samples from the same geographical origins clustered together. These results demonstrated that the IRAP technique is suitable for studying genetic diversity and population structures, and also provides an effective technique for studying sex differentiation of S. japonicum.
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Affiliation(s)
- Juan Li
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province, P R China
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Population study of Atractolytocestus huronensis (Cestoda: Caryophyllidea), an invasive parasite of common carp introduced to Europe: mitochondrial cox1 haplotypes and intragenomic ribosomal ITS2 variants. Parasitol Res 2011; 109:125-31. [DOI: 10.1007/s00436-010-2235-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 12/13/2010] [Indexed: 10/18/2022]
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Orosová M, Ivica KH, Eva B, Marta Š. Karyotype, chromosomal characteristics of multiple rDNA clusters and intragenomic variability of ribosomal ITS2 in Caryophyllaeides fennica (Cestoda). Parasitol Int 2010; 59:351-7. [DOI: 10.1016/j.parint.2010.04.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 04/27/2010] [Accepted: 04/28/2010] [Indexed: 11/30/2022]
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Morphological and molecular analysis of metacercariae of Diphtherostomum brusinae (Stossich, 1888) Stossich, 1903 from a new bivalve host Mytilus galloprovincialis. J Helminthol 2010; 85:179-84. [PMID: 20701832 DOI: 10.1017/s0022149x10000428] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The digenean trematode Diphtherostomum brusinae (Stossich, 1888) Stossich, 1903 presents a complex life cycle that may involve more than one intermediate host. The present study represents the first description of the metacercariae from D. brusinae infecting the labial palps of a new intermediate host, Mytilus galloprovincialis, in the Aveiro estuary, Portugal. The morphology of this parasitic stage was studied by light (LM) and scanning electron microscopy (SEM) and some differences were reported (body and sucker sizes, and spine distribution and shape). In this work, the 18S partial region of the ribosomal DNA was sequenced from D. brusinae metacercariae isolated from M. galloprovincialis collected in different localities of the Aveiro estuary. In addition, sequences from the same region of the 18S rDNA were obtained from D. brusinae cercariae and metacercariae, hosted by Nassarius reticulatus and Cerastoderma edule, respectively. No intraspecific polymorphism was detected in the 18S partial region, since there was 100% homology among all the sequences analysed. The same comparison was made for the ITS1, and we observed intraspecific polymorphism in this region. To our knowledge, this is the first report of D. brusinae metacercariae infecting the mussel M. galloprovincialis with support from morphological and molecular data.
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Gustinelli A, Caffara M, Florio D, Otachi EO, Wathuta EM, Fioravanti ML. First description of the adult stage of Clinostomum cutaneum Paperna, 1964 (Digenea: Clinostomidae) from grey herons Ardea cinerea L. and a redescription of the metacercaria from the Nile tilapia Oreochromis niloticus niloticus (L.) in Kenya. Syst Parasitol 2010; 76:39-51. [PMID: 20401577 DOI: 10.1007/s11230-010-9231-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 09/24/2009] [Indexed: 11/26/2022]
Abstract
The combined use of morphological and molecular studies allowed for the first time the recognition and description of the adult stage of Clinostomum cutaneum Paperna, 1964 from the grey heron Ardea cinerea L. in Kenya. A redescription of the metacercaria that infect Nile tilapia Oreochromis niloticus niloticus (L.) from the same aquatic environment is also presented. C. cutaneum differs from all other species of Clinostomum Leidy, 1856 in the shape of its uterus. Sequencing the rRNA confirmed the morphological similarity between adults from the grey heron and the metacercarial stage from tilapia, and a level of genetic similarity with the other previously sequenced Clinostomum spp. was observed. The need for a reorganisation of Clinostomum using both morphological and molecular methods is highlighted.
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MESH Headings
- Animals
- Birds/parasitology
- Cichlids/parasitology
- DNA, Helminth/chemistry
- DNA, Helminth/genetics
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- DNA, Ribosomal Spacer/chemistry
- DNA, Ribosomal Spacer/genetics
- Kenya
- Microscopy
- Microscopy, Electron, Scanning
- Molecular Sequence Data
- RNA, Ribosomal, 18S/genetics
- RNA, Ribosomal, 28S/genetics
- Sequence Analysis, DNA
- Trematoda/anatomy & histology
- Trematoda/classification
- Trematoda/isolation & purification
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Affiliation(s)
- Andrea Gustinelli
- Department of Veterinary Public Health and Animal Pathology, University of Bologna, via Tolara di Sopra 50, 40064, Ozzano Emilia, BO, Italy.
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Al-Kandari WY, Al-Bustan SA. Molecular identification of Probolocoryphe uca (Sarkisian, 1957; Digenea: Microphallidae) from Kuwait Bay using ITS1 and ITS2 sequences. Parasitol Res 2010; 106:1189-95. [DOI: 10.1007/s00436-010-1778-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Accepted: 01/19/2010] [Indexed: 12/01/2022]
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21
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Intra-individual internal transcribed spacer 1 (ITS1) and ITS2 ribosomal sequence variation linked with multiple rDNA loci: A case of triploid Atractolytocestus huronensis, the monozoic cestode of common carp. Int J Parasitol 2010; 40:175-81. [DOI: 10.1016/j.ijpara.2009.07.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Accepted: 07/06/2009] [Indexed: 11/17/2022]
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22
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Zhao GH, Li J, Lin RQ, Zou FC, Liu W, Yuan ZG, Mo XH, Song HQ, Weng YB, Zhu XQ. An effective sequence characterized amplified region-PCR method derived from restriction site-amplified polymorphism for the identification of femaleSchistosoma japonicumof zoonotic significance. Electrophoresis 2010; 31:641-7. [DOI: 10.1002/elps.200900615] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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23
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Razo-Mendivil U, Vázquez-Domínguez E, Rosas-Valdez R, de León GPP, Nadler SA. Phylogenetic analysis of nuclear and mitochondrial DNA reveals a complex of cryptic species in Crassicutis cichlasomae (Digenea: Apocreadiidae), a parasite of Middle-American cichlids. Int J Parasitol 2009; 40:471-86. [PMID: 19853608 DOI: 10.1016/j.ijpara.2009.10.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 10/04/2009] [Accepted: 10/05/2009] [Indexed: 11/29/2022]
Abstract
We obtained nuclear ITS-1 and mitochondrial cox1 sequences from 225 Crassicutis cichlasomae adults collected in 12 species of cichlids from 32 localities to prospect for the presence of cryptic species. This trematode is commonly found in species of cichlids over a wide geographic range in Middle-America. Population-level phylogenetic analyses of ITS-1 and cox1, assessments of genetic and haplotype diversity, and morphological observations revealed that C. cichlasomae represents a complex of seven cryptic species for which no morphological diagnostic characters have been discovered thus far. Bayesian and Maximum Likelihood analyses of concatenated datasets (906 bp) recovered eight lineages of C. cichlasomae, all with high posterior probabilities and bootstrap branch support. Values of genetic divergence between clades ranged from 1.0% to 5.2% for ITS-1, and from 7.2% to 30.0% for cox1. Morphological study of more than 300 individuals did not reveal structural diagnostic traits for the species defined using molecular evidence. These observations indicate that some traditional morphological characters (e.g., testes position) have substantial intra-specific variation, and should be used with caution when classifying C. cichlasomae and their sister taxa. Additionally, phylogenetic analyses did not reveal a strict correlation between these cryptic species and their host species or geographic distribution, however it appears that genetic distinctiveness of these cryptic species was influenced by the diversification and biogeographical history of Middle-American cichlids.
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Affiliation(s)
- Ulises Razo-Mendivil
- Instituto de Ecología, Universidad Nacional Autónoma de México, Ap. Postal 70-275, Ciudad Universitaria, México DF 04510, Mexico.
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Abstract
During the years 2002-2007, Icelandic freshwater snails and birds from different orders were examined for bird schistosomes. Only the snail Radix peregra and anatid birds proved to be infected. In total, 32 samples of bird schistosome cercariae from seven localities and four samples of adults of Anas platyrhynchos and Mergus serrator from two localities were used for sequencing of the internal transcibed spacer (ITS) region of rDNA. Based on the sequence and position in the phylogenetic tree, five species/genotypes of bird schistosomes were identified. Three of them correspond to the sequences in GenBank for Trichobilharzia franki, Trichobilharzia sp. JR-2007 from Anas penelope (isolates Pl7 and Pl10) and schistosomatid sp. JR-2004 from Physa fontinalis. The other two species/genotypes belong to the genus Trichobilharzia, but their further determination was not possible due to lack of data. All of these species/genotypes develop in R. peregra, probably the only suitable intermediate host species in Iceland. As T. franki and schistosomatid sp. JR-2004 were previously reported from other snail species, the findings from Iceland proved that, under some circumstances, bird schistosomes are able to adapt to a different snail species; some of them can even adapt to a snail belonging to a different gastropod family. High diversity of bird schistosomes in Iceland is probably linked with migratory flyways of birds, as several bird species from Iceland overwinter in western Europe as well as in North America.
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Razo-Mendivil U, Rosas-Valdez R, Pérez-Ponce de León G. A New Cryptogonimid (Digenea) From the Mayan Cichlid, Cichlasoma urophthalmus (Osteichthyes: Cichlidae), in Several Localities of the Yucatán Peninsula, Mexico. J Parasitol 2008; 94:1371-8. [DOI: 10.1645/ge-1546.1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Accepted: 04/30/2008] [Indexed: 11/10/2022] Open
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26
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Toward practical, DNA-based diagnostic methods for parasitic nematodes of livestock — Bionomic and biotechnological implications. Biotechnol Adv 2008; 26:325-34. [DOI: 10.1016/j.biotechadv.2008.03.003] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 03/06/2008] [Accepted: 03/14/2008] [Indexed: 11/22/2022]
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27
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Pérez-Ponce de León G, Razo-Mendivil U, Rosas-Valdez R, Mendoza-Garfias B, Mejía-Madrid H. Description of a new species of Crassicutis Manter, 1936, parasite of Cichlasoma beani Jordan (Osteichthyes: Cichlidae) in Mexico, based on morphology and sequences of the ITS1 and 28S ribosomal RNA genes. J Parasitol 2008; 94:257-63. [PMID: 18372648 DOI: 10.1645/ge-1224.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A new species of Crassicutis Manter, 1936 is described from the Sinaloan cichlid Cichlasoma beani (Jordan) (Osteichthyes: Cichlidae) in the upper Río Santiago basin. Crassicutis choudhuryi n. sp. differs from most of the other nominal species by having testes located in a symmetrical position. The only other species of the genus that includes some specimens exhibiting this trait is Crassicutis intermedius (Szidat 1954), a species found in 5 species of siluriforms and 1 species of characiform in South America. However, this species differs from Cr. choudhuryi n. sp. by having testes almost half of the size, and vitelline follicles extending anteriorly to the region between the acetabulum and the intestinal bifurcation. The new species is morphologically very similar to Crassicutis cichlasomae Manter, 1936, but clearly differs from this species because of the constantly symmetrical position of the testes. Additionally, Cr. choudhuryi n. sp. is found in the Santiago River basin on the Pacific slope of Mexico, parasitizing specifically the endemic Ci. beani that does not co-occur with any other cichlid. Cr. cichlasomae exhibits more hosts (about 25 species of cichlids only in Mexico) and a wider distribution range that extends from northeastern Mexico southward to Central America, Cuba, and Brazil. To corroborate that our specimens were not conspecific with Cr. cichlasomae, sequences of the internal transcribed spacer (ITS1) and the 28S ribosomal RNA genes of individuals from several populations (recently collected in southeastern Mexico) were obtained and compared to the species described herein. Sequence divergence (1.3% for the 28S and 4.0% for the ITS1) gives further support to the erection of a new species.
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Affiliation(s)
- Gerardo Pérez-Ponce de León
- Instituto de Biología, Universidad Nacional Autónoma de Mexico, Laboratorio de Helmintología, Ap. Postal 70-153, C.P. 04510, Mexico DF, Mexico.
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28
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Repetitive sequences in the ITS1 region of the ribosomal DNA of Tunga penetrans and other flea species (Insecta, Siphonaptera). Parasitol Res 2007; 102:193-9. [DOI: 10.1007/s00436-007-0743-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 08/21/2007] [Indexed: 10/22/2022]
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29
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Kan XZ, Wang SS, Ding X, Wang XQ. Structural evolution of nrDNA ITS in Pinaceae and its phylogenetic implications. Mol Phylogenet Evol 2007; 44:765-77. [PMID: 17596969 DOI: 10.1016/j.ympev.2007.05.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Revised: 04/24/2007] [Accepted: 05/07/2007] [Indexed: 11/29/2022]
Abstract
Nuclear ribosomal DNA (nrDNA) has been considered as an important tool for inferring phylogenetic relationships at many taxonomic levels. In comparison with its fast concerted evolution in angiosperms, nrDNA is symbolized by slow concerted evolution and substantial ITS region length variation in gymnosperms, particularly in Pinaceae. Here we studied structure characteristics, including subrepeat composition, size, GC content and secondary structure, of nrDNA ITS regions of all Pinaceae genera. The results showed that the ITS regions of all taxa studied contained subrepeat units, ranging from 2 to 9 in number, and these units could be divided into two types, longer subrepeat (LSR) without the motif (5'-GGCCACCCTAGTC) and shorter subrepeat (SSR) with the motif. Phylogenetic analyses indicate that the homology of some SSRs still can be recognized, providing important informations for the evolutionary history of nrDNA ITS and phylogeny of Pinaceae. In particular, the adjacent tandem SSRs are not more closely related to one another than they are to remote SSRs in some genera, which may imply that multiple structure variations such as recombination have occurred in the ITS1 region of these groups. This study also found that GC content in the ITS1 region is relevant to its sequence length and subrepeat number, and could provide some phylogenetic information, especially supporting the close relationships among Picea, Pinus, and Cathaya. Moreover, several characteristics of the secondary structure of Pinaceae ITS1 were found as follows: (1) the structure is dominated by several extended hairpins; (2) the configuration complexity is positively correlated with subrepeat number; (3) paired subrepeats often partially overlap at the conserved motif (5'-GGCCACCCTAGTC), and form a long stem, while other subrepeats fold onto itself, leaving part of the conserved motif exposed in hairpin loops.
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Affiliation(s)
- Xian-Zhao Kan
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China
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30
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Warberg R, Jensen KT, Frydenberg J. Repetitive sequences in the ITS1 region of ribosomal DNA in congeneric microphallid species (Trematoda: Digenea). Parasitol Res 2005; 97:420-3. [PMID: 16151738 DOI: 10.1007/s00436-005-1472-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2005] [Accepted: 07/07/2005] [Indexed: 11/26/2022]
Abstract
In searching for species-specific DNA sequences of microphallid species (Digenea, Trematoda) we examined the ribosomal internal transcribed spacer regions (ITS) of three closely related species (Levinseniella group) hosted by mud snails (first intermediate host) and marine crustaceans (second intermediate host). In the ITS1 region we found consistent patterns of repeating sequences of 130 bp. Within each main repeat there was a varying number of subrepeats specific for each of the species. All repeats including subrepeats were identified by a similar starting sequence: 5'-CCTGTGG-3'. As this sequence has close resemblance to the chi sequence 5'-GCTGGTGG-3' found in phage lambda we speculate if it serves the same function as a recombination hotspot. Alternatively but less likely, it could be an inactive, mutational relic of a sequence that once served this purpose.
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Affiliation(s)
- Rikke Warberg
- Department of Marine Ecology, University of Aarhus, Denmark
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31
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Vilas R, Criscione CD, Blouin MS. A comparison between mitochondrial DNA and the ribosomal internal transcribed regions in prospecting for cryptic species of platyhelminth parasites. Parasitology 2005; 131:839-46. [PMID: 16336737 DOI: 10.1017/s0031182005008437] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2005] [Revised: 05/12/2005] [Accepted: 05/31/2005] [Indexed: 11/05/2022]
Abstract
We examined the relative merits of mitochondrial DNA loci and ribosomal DNA internal transcribed spacers for their use in prospecting for cryptic species of platyhelminth parasites. Sequence divergence at ITS1 and ITS2 was compared with divergence at 2 mtDNA loci (NADH dehydrogenase-1 and cytochrome c oxidase I) between closely related species of trematodes and cestodes. Both spacers accumulated substitutions substantially more slowly than mtDNA, which clearly shows a higher level of divergence among species relative to intra-specific variation. Besides a slow rate of substitution, other caveats that may be encountered when using ITS sequences as a prospecting marker are discussed. In particular, we note recent studies that suggest the existence of substantial levels of intra-individual variation in ITS sequences of flatworms. Because it is likely that closely related species share this phenomenon, it may confound the detection of cryptic species, especially if small sample sizes are studied. Although potential limitations of mtDNA are also recognized, the higher rate of evolution and smaller effective population size of this marker increases the probability of detecting diagnostic characters between cryptic species.
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Affiliation(s)
- R Vilas
- Department of Zoology, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331, USA.
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32
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Wang DM, Yao YJ. Intrastrain internal transcribed spacer heterogeneity inGanodermaspecies. Can J Microbiol 2005; 51:113-21. [PMID: 16091769 DOI: 10.1139/w04-118] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intrastrain internal transcribed spacer (ITS) heterogeneity is first reported from Ganoderma, a fungal genus within Basidiomycetes. ITS amplification products from 4 strains, representing 4 Ganoderma species, were cloned and sequenced. Two to five different ITS types were found within a single strain. The clone sequences were analyzed along with other sequences from Ganoderma retrieved from GenBank. The results show that sequence variation within strains varies considerably with species and the heterogeneity may occur in the 3 parts (ITS1, ITS2, and 5.8S) of the ITS region.Key words: intragenomic ITS heterogeneity, polymorphism, Ganoderma.
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Affiliation(s)
- D-M Wang
- Systematic Mycology and Lichenology Laboratory, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, China
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Olson PD, Tkach VV. Advances and Trends in the Molecular Systematics of the Parasitic Platyhelminthes. ADVANCES IN PARASITOLOGY 2005; 60:165-243. [PMID: 16230104 DOI: 10.1016/s0065-308x(05)60003-6] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The application of molecular systematics to the parasitic Platyhelminthes (Cestoda, Digenea and Monogenea) over the last decade has advanced our understanding of their interrelationships and evolution substantially. Here we review the current state of play and the early works that led to the molecular-based hypotheses that now predominate in the field; advances in their systematics, taxonomy, classification and phylogeny, as well as trends in species circumscription, molecular targets and analytical methods are discussed for each of the three major parasitic groups. A by-product of this effort has been an ever increasing number of parasitic flatworms characterized genetically, and the useful application of these data to the diagnosis of animal and human pathogens, and to the elucidation of life histories are presented. The final section considers future directions in the field, including taxon sampling, molecular targets of choice, and the current and future utility of mitochondrial and nuclear genomics in systematic study.
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Affiliation(s)
- Peter D Olson
- Division of Parasitology, Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
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Nolan MJ, Cribb TH. The Use and Implications of Ribosomal DNA Sequencing for the Discrimination of Digenean Species. ADVANCES IN PARASITOLOGY 2005; 60:101-63. [PMID: 16230103 DOI: 10.1016/s0065-308x(05)60002-4] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In just over a decade, the use of molecular approaches for the recognition of parasites has become commonplace. For trematodes, the internal transcribed spacer region of ribosomal DNA (ITS rDNA) has become the default region of choice. Here, we review the findings of 63 studies that report ITS rDNA sequence data for about 155 digenean species from 19 families, and then review the levels of variation that have been reported and how the variation has been interpreted. Overall, complete ITS sequences (or ITS1 or ITS2 regions alone) usually distinguish trematode species clearly, including combinations for which morphology gives ambiguous results. Closely related species may have few base differences and in at least one convincing case the ITS2 sequences of two "good" species are identical. In some cases, the ITS1 region gives greater resolution than the ITS2 because of the presence of variable repeat units that are generally lacking in the ITS2. Intraspecific variation is usually low and frequently apparently absent. Information on geographical variation of digeneans is limited but at least some of the reported variation probably reflects the presence of multiple species. Despite the accepted dogma that concerted evolution makes the individual representative of the entire species, a significant number of studies have reported at least some intraspecific variation. The significance of such variation is difficult to assess a posteriori, but it seems likely that identification and sequencing errors account for some of it and failure to recognise separate species may also be significant. Some reported variation clearly requires further analysis. The use of a "yardstick" to determine when separate species should be recognised is flawed. Instead, we argue that consistent genetic differences that are associated with consistent morphological or biological traits should be considered the marker for separate species. We propose a generalised approach to the use of rDNA to distinguish trematode species.
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Affiliation(s)
- Matthew J Nolan
- School of Molecular and Microbial Sciences and Centre for Marine Studies, Parasitology Section, The University of Queensland, Brisbane, Queensland 4072, Australia
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35
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Razo-Mendivil UJ, León-Règagnon V, Pérez-Ponce de León G. Description of two new species of Glypthelmins Stafford, 1905 (Digenea: Macroderoididae) in Rana spp. from Mexico, based on morphology and mtDNA and rDNA sequences. Syst Parasitol 2004; 59:199-210. [PMID: 15542949 DOI: 10.1023/b:sypa.0000048099.73779.f4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Glypthelmins Stafford, 1905 includes 29 putative species commonly found in the intestine and liver of anurans from all over the world but mainly in the Americas. Partial sequences of the cytochrome c oxidase subunit 1 ( cox 1), ribosomal internal transcribed spacer region 2 (ITS2) and the large subunit 28S rDNA gene were obtained and analysed using pairwise distance matrices and parsimony methods in order to characterise the interrelationships between 14 isolates of four nominal species of Glypthelmins recognised on morphological grounds. The highest intra-specific sequence divergence occurred in the cox 1 (18.53%) sequence, followed by that of the ITS2 (5.44%) and 28S (4.63%). Genetic variability was detected between the three isolates originally identified as G. facioi Brenes et al., 1959 from two localities in Mexico and one locality in Costa Rica. Sequence divergence exhibited among these isolates ranged from 10.70 to 11.22%, from 0.48 to 0.97% and from 1.33 to 1.88% for cox 1, ITS2 and 28S, respectively. Phylogenetic analysis combining all three data-sets generated a single most parsimonious tree. The three isolates of G. facioi form a clade, with an isolate collected from frogs in Veracruz State as the sister group to an isolate from Tabasco State + G. facioi from Costa Rica. The information derived from pairwise distance of independent data-sets plus the phylogenetic information indicate that each of the two isolates from Mexico, identified a priori as G. facioi, represent separate species. A re-examination of specimens was carried out and a re-evaluation made of the morphological characters to find reliable differences that had been overlooked. As a consequence, G. brownorumae n. sp. from Tabasco and G. tuxtlasensis n. sp. from Veracruz are described based on molecular and morphological differences.
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Affiliation(s)
- Ulises J Razo-Mendivil
- Laboratorio de Helmintología, Instituto de Biología, Universidad Nacional Autónoma de México. Ap. Postal 70-153. Del. Coyoacán. C. P. 04510 México, D.F. México
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36
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Van Herwerden L, Caley MJ, Blair D. Regulatory motifs are present in the ITS1 of some flatworm species. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2003; 296:80-6. [PMID: 12658712 DOI: 10.1002/jez.b.8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Particular sequence motifs can act as transcription regulators. Because the total regulatory effects of such motifs can be related to their abundance, their presence might be expected at locations within the genome where sequences are repeated. Multiple repeats that vary in number among individuals occur within the ribosomal first internal transcribed spacer (ITS1) in some species in three trematode genera: Paragonimus, Schistosoma and Dolichosaccus. In all of these genera we found in ITS1, sequences identical to known enhancer motifs. We also searched for, and identified, known regulatory motifs in published ITS1 sequences of other parasitic flatworms including Echinostoma spp. (Trematoda) and Echinococcus spp. (Cestoda) which lack multiple repeats in ITS1. We present three lines of evidence that this widespread occurrence of such motifs within the ITS1 of parasitic flatworms may indicate a functional role in regulating tissue- or stage-specific transcription of ribosomal genes. First, these motifs are identical to ones whose functional roles have been established using in vitro assays of transcriptional rates. Second, in all 18 species investigated here, between one and three different regulatory motifs were identified. In 14 of these 18 species, the probability that at least one of these motifs occurred because of the random assortment of bases within the regions investigated was 10% or less. In 12 of these 14 species, the probability was 5% or less. Third, the evolutionary divergence of flatworm species investigated is quite ancient. Therefore, the interspecific distribution of motifs observed here, in a rapidly evolving region such as ITS1, is unlikely to be attributable solely to shared evolutionary histories. These results, therefore, suggest a broader functional role for the ITS1 than previously thought.
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Affiliation(s)
- Lynne Van Herwerden
- Centre for Coral Reef Biodiversity, School of Marine Biology and Aquaculture, James Cook University, Townsville, Queensland 4811, Australia.
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Abstract
The first internal transcribed spacer (ITS1) of nuclear ribosomal DNA from Culicoides arakawae was amplified by PCR, cloned and sequenced. The wDNAsis software was used to analyze the ITS1 sequences of C. arakawae and other nine species of Culicoides, which were obtained from GenBank and EMBL databases. For all species, the lengths of the ITS1 were 316-469 bp, and the G+C contents were 26.79-34.53%. Based on the lengths of the ITS1 sequences, the 10 Culicoides species could be divided into two groups. The first group consisted of C. arakawae, C. albicans, C. cubitalis, C. pulicaris and C. punctatus, and the second group comprised C. impunctatus, C. nubeculosus, C. variipennis, C. grisescens and C. imicola. The lengths for the first group were 316-347 bp and the second group were 457-469 bp. C. arakawae belonged to the first group by its ITS1 sequence length. Sequence analysis revealed that C. arakawae was genetically more similar to the first group than it was to the second group, consistent with results based on sequence length. The alignment of ITS1 (the alignment length was 500 bp including the gaps) sequences showed that there was a highly conserved region, which was between 288 and 388 bp, except for a few insertions and substitutions. These findings have important implications for the molecular identification of C. arakawae, for studying its molecular genetics and epidemiology, and for studying the molecular systematics of Culicoides.
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Affiliation(s)
- G Q Li
- College of Veterinary Medicine, South China Agricultural University, Wushan, Tianhe District, Guangzhou 510642, PR China.
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38
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Bell AS, Sommerville C. Molecular evidence for the synonymy of two species of Apatemon Szidat, 1928, A. gracilis (Rudolphi, 1819) and A. annuligerum (von Nordmann, 1832) (Digenea: Strigeidae) parasitic as metacercariae in British fishes. J Helminthol 2002; 76:193-8. [PMID: 12363371 DOI: 10.1079/joh2002120] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The current study examined rDNA (internal transcribed spacer regions, ITS1 and ITS2) and cytochrome c oxidase subunit 1 (CO1) sequence data of Apatemon annuligerum (originating from two geographical locations) and A. gracilis metacercariae (originating from four natural piscine hosts) to determine the systematic status of these two strigeid digeneans. With the exception of short repeat motifs, the ITS1 regions sequenced demonstrated no intra- or inter-specific sequence variation. ITS2 sequences were 292 bp and CO1 sequences 366 bp in length and identical for both nominal Apatemon species. These sequence data provide strong evidence that the two species are con-specific and that A. annuligerum should be regarded as a junior synonym of A. gracilis.
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Affiliation(s)
- A S Bell
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
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39
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Hancock K, Broughel DE, Moura IN, Khan A, Pieniazek NJ, Gonzalez AE, Garcia HH, Gilman RH, Tsang VC. Sequence variation in the cytochrome oxidase I, internal transcribed spacer 1, and Ts14 diagnostic antigen sequences of Taenia solium isolates from South and Central America, India, and Asia. Int J Parasitol 2001; 31:1601-7. [PMID: 11730787 DOI: 10.1016/s0020-7519(01)00295-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We examined the genetic variability in the pig-human tapeworm, Taenia solium, by sequencing the genes for cytochrome oxidase I, internal transcribed spacer 1, and a diagnostic antigen, Ts14, from individual cysts isolated from Peru, Colombia, Mexico, India, China, and the Philippines. For these genes, the rate of nucleotide variation was minimal. Isolates from these countries can be distinguished based on one to eight nucleotide differences in the 396 nucleotide cytochrome oxidase I (COI) sequence. However, all of the 15 isolates from within Peru had identical COI sequences. The Ts14 sequences from India and China were identical and differed from the Peru sequence by three nucleotides in 333. These data indicate that there is minimal genetic variability within the species T. solium. Minimal variability was also seen in the ITS1 sequence, but this variation was observed within the individual. Twenty-two cloned sequences from six isolates sorted into 13 unique sequences. The variability observed within the sequences from individual cysts was as great as the variability between the isolates.
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Affiliation(s)
- K Hancock
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Bldg 23, Room 1001, Mail Stop F-13, 4770 Buford Highway, Atlanta, GA 30341, USA.
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40
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Gasser RB, Chilton NB. Applications of single-strand conformation polymorphism (SSCP) to taxonomy, diagnosis, population genetics and molecular evolution of parasitic nematodes. Vet Parasitol 2001; 101:201-13. [PMID: 11707297 DOI: 10.1016/s0304-4017(01)00567-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The analysis of genetic variation in parasitic nematodes has important implications for studying aspects of taxonomy, diagnosis, population genetics, drug resistance and molecular evolution. This article highlights some applications of PCR-based single-strand conformation polymorphism (SSCP) for the analysis of sequence variation in individual parasites (and their populations) to address some of these areas. It also describes the principles and advantages of SSCP, and provides some examples for future applications in parasitology.
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Affiliation(s)
- R B Gasser
- Department of Veterinary Science, The University of Melbourne, 250 Princes Highway, Werribee, Victoria 3030, Australia.
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41
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Bell AS, Sommerville C, Tellervo Valtonen E. A molecular phylogeny of the genus Ichthyocotylurus (Digenea, Strigeidae). Int J Parasitol 2001; 31:833-42. [PMID: 11403776 DOI: 10.1016/s0020-7519(01)00181-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Three nucleotide data sets, two nuclear (ribosomal internal transcribed spacer regions 1 and 2, ITS1 and ITS2) and one mitochondrial (cytochrome c oxidase subunit 1, CO1), were analysed using distance matrix and maximum likelihood methods to determine the inter-relationships amongst the four species attributed to the genus Ichthyocotylurus Odening, 1969. Sequence data obtained from all gene loci investigated supported the position of Ichthyocotylurus variegatus as a species discrete from Ichthyocotylurus platycephalus. Phylogenetic analyses yielded congruent trees, with I. variegatus isolates comprising a common clade to which I. platycephalus constitutes a sister taxon. Ichthyocotylurus erraticus and Ichthyocotylurus pileatus were found to demonstrate a similarly close inter-specific relationship. The greatest intra-generic divergence occurred in the CO1 region (16% variability), with resultant disparities in three to eight encoded amino acids. PCR amplification yielded multiple ITS1 products for all Ichthyocotylurus spp. Analyses of equivalent-sized amplicons showed 5.4% intra-generic variation and several point mutations between I. variegatus isolates from different geographical localities and from different piscine hosts. The ITS2 locus was extremely conserved, with less than 1% variation between species. No intra-specific variation was recorded for any CO1 or ITS2 sequences.
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Affiliation(s)
- A S Bell
- Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK.
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42
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Matejusová I, Gelnar M, McBeath AJ, Collins CM, Cunningham CO. Molecular markers for gyrodactylids (Gyrodactylidae: Monogenea) from five fish families (Teleostei). Int J Parasitol 2001; 31:738-45. [PMID: 11336756 DOI: 10.1016/s0020-7519(01)00176-x] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Thirty-one gyrodactylid species from five families of freshwater fish were examined and variable region V4 of the 18S small subunit ribosomal RNA gene and ribosomal RNA internal transcribed spacers ITS1 and ITS2 were sequenced. Both the V4 region and spacers ITS1 and ITS2 proved useful for gyrodactylid diagnosis. Sequences of these fragments exhibited interspecific variations and allowed clear determination at the species level. In some cases, the length of the ITS1 PCR fragment provided useful genetic markers. Species that yielded a short ITS1 fragment also showed distinct groupings in ITS2 and V4 sequences that were markedly different to sequences from species that contain a long ITS1. Repetitive sequences located in the ITS1 of Gyrodactylus gobii and Gyrodactylus vimbi accounted for some of the variations in length of PCR products. There was no evidence for intraspecific variation within these regions and short tandem repeats were not found in the other species studied. The number of polymorphic and intraspecific variations in nucleic acid sequences was low, therefore these variations did not affect species determination of gyrodactylids. Minor differences in the sequences between Western and Eastern European populations were detected for Gyrodactylus salaris/Gyrodactylus thymalli, Gyrodactylus teuchis and Gyrodactylus truttae, but these do not affect species diagnosis based on ribosomal DNA sequence. These results confirm the utility of both variable region V4 and the ITS as molecular markers for Gyrodactylus species.
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Affiliation(s)
- I Matejusová
- Department of Zoology and Ecology, Faculty of Science, Masaryk University, Kotlárská 2, 611 37, Brno, Czech Republic
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43
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Gasser RB, Zhu X, Beveridge I, Chilton N. Mutation scanning analysis of sequence heterogeneity in the second internal transcribed spacer (rDNA) within some members of theHypodontus macropi (Nematoda: Strongyloidea) complex. Electrophoresis 2001; 22:1076-85. [PMID: 11358128 DOI: 10.1002/1522-2683()22:6<1076::aid-elps1076>3.0.co;2-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Single-strand conformation polymorphism analysis was employed to investigate sequence variation in the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA within and among individuals representing three operational taxonomic units (OTUs) of Hypodontus macropi from different species of Australian macropodid marsupials. Of the 96 nematodes analysed, totals of 3 (OTU1 from Petrogale persephone), 10 (OTU2 from Macropus robustus) and 7 (OTU9 from Macropus rufus) representative individuals were selected for DNA sequencing to characterise and estimate the magnitude of nucleotide variation in the ITS-2. While no unequivocal nucleotide difference in the ITS-2 was detectable within OTU1, most sequence variation (3/44.7%) detected within OTU2 and OTU9 was related chiefly to dinucleotide (CA, TA, or a combination of both) differences. This microsatellite variability in some H. macropi OTUs suggests that the ITS-2 rDNA may be subjected to slippage events during DNA replication, resulting in short dinucleotide repeat tracts being dispersed throughout the ITS-2 lineages, or possibly transposition and/or crossing-over events. Nucleotide variation in the ITS-2 of individual OTUs was related to the proposed secondary structure for the precursor ribosomal RNAs. Most of the sequence heterogeneity or polymorphism within OTU2 and OTU9 occurred in loops or bulges of the predicted secondary structure, which appear not to be under functional constraint. The findings of this study have implications for investigating speciation events and population differentiation in nematodes at the molecular level.
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Affiliation(s)
- R B Gasser
- Department of Veterinary Science, The University of Melbourne, Werribee, Victoria, Australia.
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44
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von der Schulenburg JH, Hancock JM, Pagnamenta A, Sloggett JJ, Majerus ME, Hurst GD. Extreme length and length variation in the first ribosomal internal transcribed spacer of ladybird beetles (Coleoptera: Coccinellidae). Mol Biol Evol 2001; 18:648-60. [PMID: 11264417 DOI: 10.1093/oxfordjournals.molbev.a003845] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
DNA sequences of the first ribosomal internal transcribed spacer (ITS1) were isolated from 10 ladybird beetle species (Coleoptera: Coccinellidae) representing four subfamilies (Coccinellinae, Chilocorinae, Scymninae, and Coccidulinae). The spacers ranged in length from 791 to 2,572 bp, thereby including one of the longest ITS1s and exhibiting one of the most extreme cases of ITS1 size variation in eukaryotes recorded to date. The causes of length variation were therefore analyzed. Almost no putatively homologous sequence similarities were identified for the taxa included. The only exception was for the subfamily Coccinellinae, which yielded sequence similarities in six regions of approximately 550 nucleotide positions, primarily at the 5' and 3' ends of ITS1. The majority of differences in ITS1 length between taxa could be attributed to the presence of repetitive elements with comparatively long repeat units. Repetition arose several times independently and was confined to the middle of the spacer which, in contrast to the 5' and 3' ends, had not been inferred in previous studies to be subject to functional constraints. These elements were characterized by high rates of evolutionary change, most likely as a result of high substitution rates in combination with inefficient homogenization across repeats. The repeated origin and subsequent divergence of "long" repetitive elements should thus be assumed to be an important factor in the evolution of coccinellid ITS1.
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45
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Som I, Azam A, Bhattacharya A, Bhattacharya S. Inter- and intra-strain variation in the 5.8S ribosomal RNA and internal transcribed spacer sequences of Entamoeba histolytica and comparison with Entamoeba dispar, Entamoeba moshkovskii and Entamoeba invadens. Int J Parasitol 2000; 30:723-8. [PMID: 10856506 DOI: 10.1016/s0020-7519(00)00050-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The ribosomal RNA genes in Entamoeba histolytica are located on circular DNA molecules in about 200 copies per genome equivalent. Nucleotide sequence analysis of the 5.8S rRNA gene and the flanking internal transcribed spacers was carried out to determine the degree of sequence divergence in the multiple rRNA gene copies of a given strain; amongst three different E. histolytica strains (HM-1:IMSS, Rahman and HK-9); and amongst four species of Entamoeba (Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii and Entamoeba invadens). The results show that all rRNA gene copies of a given strain are identical. Few nucleotide positions varied between strains of a species but the differences were very pronounced amongst species. In general, the internal transcribed spacer 2 sequence was more variable and may be useful for strain- and species-identification. The 5.8S rRNA gene and the internal transcribed spacer 2 of E. invadens were unusually small in size.
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Affiliation(s)
- I Som
- School of Environmental Sciences, Jawaharlal Nehru University, 110067, New Delhi, India
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46
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van Herwerden L, Gasser RB, Blair D. ITS-1 ribosomal DNA sequence variants are maintained in different species and strains of Echinococcus. Int J Parasitol 2000; 30:157-69. [PMID: 10704599 DOI: 10.1016/s0020-7519(00)00002-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
This study investigated sequence heterogeneity in the first internal transcribed spacer (ITS-1) of ribosomal DNA within and among species and strains of Echinococcus. Different ITS-1 sequence variants exist in Echinococcus granulosus and Echinococcus multilocularis, which represent at least four evolutionary lineages: (1) a sheep strain-lineage of E. granulosus, (2) a sister lineage of a cervid and camel E. granulosus ITS-1 variants, (3) a lineage including the ITS-1 variants representing horse, bovine and camel strains of E. granulosus, as well as variants from E. multilocularis, Echinococcus oligarthrus and Echinococcus vogeli and (4) a distinct lineage of ITS-1 variants including E. granulosus strains from sheep and cervid, and E. multilocularis. At least two of the species (E. granulosus and E. multilocularis) were paraphyletic for ITS-1. Divergent ITS-1 variants from these two species shared distinct evolutionary lineages. The sequence data provided evidence that at least two turnover mechanisms, namely slippage and unequal crossing over/transposition, have led to the divergence and maintenance of sequence variants in Echinococcus species and strains.
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Affiliation(s)
- L van Herwerden
- Department of Veterinary Science, The University of Melbourne, 250 Princes Highway, Werribee, Australia
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47
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Jousson O, Bartoli P, Pawlowski J. Molecular identification of developmental stages in Opecoelidae (Digenea). Int J Parasitol 1999; 29:1853-8. [PMID: 10616931 DOI: 10.1016/s0020-7519(99)00124-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Nuclear ribosomal DNA sequences represent a useful tool for distinction of poorly differentiated developmental stages, such as trematode cercariae or metacercariae. Here, the complete internal transcribed spacer region of the ribosomal DNA (ITS 1 + 5.8S + ITS 2) was sequenced for 29 specimens of the digenean family Opecoelidae, including 16 adult specimens and 13 undescribed larval stages (nine cercariae and four metacercariae) occurring in various marine host organisms. Six cercariae and three metacercariae were found to match their corresponding adult form. This work also revealed that cercariae of the same species are able to infect more than one gastropod host species, suggesting that the specificity for the first intermediate host within the Digenea may be lower than previously thought.
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Affiliation(s)
- O Jousson
- Département de Zoologie et Biologie Animale, Université de Genève, Chêne-Bougeries, Switzerland.
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48
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van Herwerden L, Blair D, Agatsuma T. Genetic diversity in parthenogenetic triploid Paragonimus westermani. Int J Parasitol 1999; 29:1477-82. [PMID: 10579435 DOI: 10.1016/s0020-7519(99)00072-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Paragonimus westermani is a medically important foodborne trematode occurring throughout southeast Asia. We have used molecular techniques to test the hypothesis that the parthenogenetic triploid form of P. westermani has arisen only once. Sources of data for comparison were: (a) restriction fragment length polymorphisms (RFLPs) of ribosomal internal transcribed spacers (ITS); and (b) 'fingerprint' patterns observed when genomic digests were probed with simple sequence repeats (ATT)10 and (ATGT)7. In all cases there were distinct differences among triploid isolates from southwest Japan, northeast China and Korea. These findings are considered in the context of previous cytogenetic, allozyme, mitochondrial-RFLP and partial cytochrome c-oxidase subunit I (COI) sequence studies and indicate that triploid lineages may have arisen independently on more than one occasion. We favour this view. An alternative explanation is that the triploids did have a single origin, but that different clonal lineages have undergone subsequent mutations.
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Affiliation(s)
- L van Herwerden
- Zoology Department, James Cook University, Townsville, Queensland, Australia.
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49
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Abstract
DNA technology is having a major impact in many areas of veterinary parasitology. In particular, the polymerase chain reaction (PCR) has found broad applicability because its sensitivity permits enzymatic amplification of gene fragments from minute quantities of nucleic acids derived from limited amounts of parasite material. This paper discusses some recent applications of PCR-based methods to parasites and highlights their usefulness or potential for those of veterinary importance. The focus is on PCR tools for the accurate identification of parasites and their genetic characterisation, the diagnosis of infections, the isolation and characterisation of expressed genes, the detection of anthelmintic resistance, and mutation scanning approaches for the high resolution analysis of PCR products.
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MESH Headings
- Animals
- DNA, Helminth/analysis
- DNA, Helminth/chemistry
- DNA, Protozoan/analysis
- DNA, Protozoan/chemistry
- Drug Resistance
- Eukaryota/classification
- Eukaryota/genetics
- Eukaryota/isolation & purification
- Expressed Sequence Tags
- Helminthiasis, Animal/diagnosis
- Helminths/classification
- Helminths/genetics
- Helminths/isolation & purification
- Microsatellite Repeats
- Parasitic Diseases, Animal/diagnosis
- Parasitic Diseases, Animal/therapy
- Polymerase Chain Reaction/methods
- Polymerase Chain Reaction/veterinary
- Polymorphism, Restriction Fragment Length
- Polymorphism, Single-Stranded Conformational
- Protozoan Infections, Animal/diagnosis
- Random Amplified Polymorphic DNA Technique/veterinary
- Sequence Analysis, DNA/veterinary
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Affiliation(s)
- R B Gasser
- Department of Veterinary Science, The University of Melbourne, Werribee, Victoria, Australia.
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50
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van Herwerden L, Blair D, Agatsuma T. Intra- and interindividual variation in ITS1 of paragonimus westermani (Trematoda: digenea) and related species: implications for phylogenetic studies. Mol Phylogenet Evol 1999; 12:67-73. [PMID: 10222162 DOI: 10.1006/mpev.1998.0572] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the utility of the ribosomal first internal transcribed spacer (ITS1) for phylogenetic studies on trematodes of the genus Paragonimus. Numerous clones containing ITS1 PCR products were sequenced for P. miyazakii, P. macrorchis, and members of the P. ohirai and P. westermani species complexes. Some additional data were obtained by direct sequencing of PCR products. The ITS1 is composed of three distinct regions: the short 5' end, followed by a tract of approximately 120 nucleotides which occurs a variable number of times in tandem, and the 3' region, which lacks repeats and is referred to as the "post-repeat" fragment. Sequences from all three regions can be aligned among the species studied. Our initial hypothesis, that the post-repeat region would be valuable for phylogenetic studies within the P. westermani complex, was proved wrong. Intraindividual sequence variation in P. westermani was sometimes greater than between individuals of the species complex. In the P. ohirai species complex, however, sequence variation within individuals was minimal. Possible reasons for these observations are discussed. We also wished to determine whether the length variants sequenced were the dominant variants present in Paragonimus species. This was done by probing Southern blots of genomic digests with an ITS1 fragment which lacks repeat sequences. There is generally greater abundance of large variants, with much lower abundance of small variants, such as those sequenced. Differences in ITS1 lengths are attributed largely to differing numbers of repeats, though some exceptions (which are discussed) were found.
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Affiliation(s)
- L van Herwerden
- Zoology Department, James Cook University, Townsville, Queensland, 4811, Australia
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