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Yang H, Wang Z, Xiao J, Hu J, Tu X, Gu Z. Integrated morphological and transcriptome profiles reveal a highly-developed extrusome system associated to virulence in the notorious fish parasite, Ichthyophthirius multifiliis. Virulence 2023; 14:2242622. [PMID: 37551042 PMCID: PMC10411306 DOI: 10.1080/21505594.2023.2242622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/12/2023] [Accepted: 07/25/2023] [Indexed: 08/09/2023] Open
Abstract
Ichthyophthirius multifiliis is an obligate parasitic ciliate that causes severe economic damage in aquaculture. The parasite contains numerous extrusive organelles (extrusomes) that assist in its pathogenesis and reproduction. However, the structure of these extrusomes and the molecular profiles involved in exocytosis remain unclear. In the present study, through comparative ultrastructural observations across the life cycle of I. multifiliis, we demonstrated that all three of its life stages (theront, trophont, and tomont) exhibited an abundance of extrusomes. In addition, two different types of extrusomes were identified according to their unique structures. Type I extrusomes (mucocysts) are crystalline, oval-shaped, 0.7-1.4 × 0.6-1.1 μm, and distributed as "rosettes" below the trophont membrane. Type II extrusomes, 2.0-3.0 × 0.2-0.3 μm, are rod-shaped with tubular cores and identified as toxicysts, the aggregation of which in the anterior part of the theront and cortex of the trophont revealed their potential roles in I. multifiliis invasion. This was confirmed by our transcriptome investigations of the three stages of I. multifiliis, which revealed that a set of genes involved in proteolysis and DNA/protein biogenesis was highly expressed in the theront and trophont. Furthermore, to map the molecular mechanisms of extrusome release, we characterized 25 Rab family genes in I. multifiliis and determined their expression profiles across the life cycle, reflecting the distribution patterns of the two extrusomes. Collectively, our data revealed that a highly developed extrusome system could play a potential role in the virulence of I. multifiliis, which facilitates a better understanding of the parasite's development.
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Affiliation(s)
- Hao Yang
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
- National Aquatic Animal Diseases Para-Reference Laboratory (HZAU), Wuhan, China
| | - Zhe Wang
- Marine College, Shandong University, Weihai, China
| | - Jieyin Xiao
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
- National Aquatic Animal Diseases Para-Reference Laboratory (HZAU), Wuhan, China
| | - Jingbo Hu
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
- National Aquatic Animal Diseases Para-Reference Laboratory (HZAU), Wuhan, China
| | - Xiao Tu
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
- National Aquatic Animal Diseases Para-Reference Laboratory (HZAU), Wuhan, China
| | - Zemao Gu
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
- National Aquatic Animal Diseases Para-Reference Laboratory (HZAU), Wuhan, China
- Hubei Hongshan Laboratory, Wuhan, China
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Ultrastructure observation on the cells at different life history stages of Cryptocaryon irritans (Ciliophora: Prostomatea), a parasitic ciliate of marine fishes. Parasitology 2016; 143:1479-89. [DOI: 10.1017/s0031182016001074] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
SUMMARYCells of Cryptocaryon irritans at different life history stages were studied using both light and electron microscopy. The characteristics of several organelles were revealed for the first time at the ultrastructural level. It was confirmed that the cytostome of trophonts, protomonts and theronts was surrounded by cilium–palp triplets rather than ciliary triplets. The nematodesmata underlying the circumoral dikinetids were single bundles, whereas these were always paired in Prorodontids. Toxicysts were present in late-stage tomonts and theronts, but were absent in trophonts and protomonts. We posited that toxicysts might play a role in infection and invasion of host-fish tissue by theronts. The adoral brosse was unlike that of any other family of the class Prostomatea based on its location and morphology. Membranous folds were present in trophonts, protomonts and theronts. These folds were longer and more highly developed in C. irritans than in exclusively free-living prostome ciliates suggesting that they might be linked to parasitism in C. irritans. Trophonts, protomonts and theronts had multiple contractile vacuoles. The basic ultrastructure of the contractile vacuole of C. irritans was similar to that of other kinetofragminophoran ciliates. They might play different roles in different stages of the life cycle since their ultrastructure varied among trophonts, protomonts and theronts.
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Kivimaki KL, Bowditch BM, Riordan GP, Lipscomb DL. Phylogeny and systematic position of Zosterodasys (Ciliophora, Synhymeniida): a combined analysis of ciliate relationships using morphological and molecular data. J Eukaryot Microbiol 2009; 56:323-38. [PMID: 19602078 DOI: 10.1111/j.1550-7408.2009.00403.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The Synhymeniida is characterized both by a band of somatic dikinetids, the synhymenium, extending across the surface of the cell and by a ventral cell mouth lacking specialized feeding cilia but subtended by a well-developed cyrtos. The synhymeniids have been hypothesized to be members of the class Nassophorea but our previous ultrastructural study of the synhymeniid genus Zosterodasys did not show any clear synapomorphies that would permit definitive placement in the Nassophorea or as a sister taxon to any of the other ciliate groups possessing a cyrtos. In the present study, simultaneous analysis of morphological and small subunit rDNA molecular data indicates that the Synhymeniida are sister to the class Phyllopharyngea and that this clade is, in turn, sister to the remaining Nassophorea, although this result is sensitive to dataset inclusion and alignment parameters. While this suggests that taxa with a ventral cyrtos might be united into a named taxon (e.g. resurrecting the Hypostomata), additional data are needed to reach a definitive conclusion.
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Affiliation(s)
- K Lindholm Kivimaki
- Department of Biological Sciences, George Washington University, Washington, District of Columbia 20052, USA
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EWING MARGARETS, LYNN MELANIEE, EWING SA. Critical Periods in Development ofIchthyophthirius multifiliis(Ciliophora) Populations1. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1986.tb05628.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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EWING MARGARETS, KOCAN KATHERINEM. Ichthyophthirius multifiliis(Ciliophora) Development in Gill Epithelium1. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1986.tb05625.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Paramá A, Arranz JA, Alvarez MF, Sanmartín ML, Leiro J. Ultrastructure and phylogeny of Philasterides dicentrarchi (Ciliophora, Scuticociliatia) from farmed turbot in NW Spain. Parasitology 2006; 132:555-64. [PMID: 16388691 DOI: 10.1017/s0031182005009534] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Revised: 10/21/2005] [Accepted: 10/21/2005] [Indexed: 11/07/2022]
Abstract
Several species of opportunistic histophagous scuticociliates have been implicated in systemic infections of farmed fish. In turbot, scuticociliatosis is an emerging disease, and the identification of the parasite species involved is controversial. We have previously isolated Philasterides dicentrarchi from farmed turbot scuticociliatosis outbreaks in northwest Spain. In the present study, we report detailed ultrastructural studies of this parasite, and investigate phylogenetic relations with other members of the order Philasterida on the basis of sequence comparison of the small-subunit rRNA (SSUrRNA) gene. Ultrastructural study indicates the presence of dikinetids in the anterior two-thirds of the body; micronucleus closely associated with the macronucleus, though not physically connected; numerous mitochondria located below the cell cortex, parallel to the surface; numerous spherical and fusiform extrusomes located close to the plasma membrane. We consider that these characteristics are useful for diagnosis of infections by this parasite. A nested 350-bp nucleotide sequence of the SSUrRNA gene of the turbot P. dicentrachi isolate showed high identity with previously reported SSUrRNA gene sequences from 2 scuticociliates isolated from olive flounder Paralichthys olivaceus in Korea, namely P. dicentrarchi (98%) and Miamiensis avidus (99%); conversely, our P. dicentrarchi sequence showed low identity (86%) with that of Uronema marinum, a scuticociliate that has also been implicated in scuticociliatosis outbreaks in turbot in Europe and olive flounder in Asia. Phylogenetic tree construction on the basis of the SSUrRNA gene sequences, using the neighbour-joining method, confirm that the different P. dicentrarchi isolates and M. avidus are closely related and a possible synonymy between both ciliates species should be considered.
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Affiliation(s)
- A Paramá
- Laboratorio de Parasitología, Departamento de Microbiología y Parasitología, Instituto de Investigación y Análisis Alimentarios, Universidad de Santiago de Compostela, C/ Constantino Candeira s/n, 15782, Santiago de Compostela, Spain
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Matthews RA. Ichthyophthirius multifiliis Fouquet and Ichthyophthiriosis in Freshwater Teleosts. ADVANCES IN PARASITOLOGY 2005; 59:159-241. [PMID: 16182866 DOI: 10.1016/s0065-308x(05)59003-1] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The ciliate Ichthyophthirius multifiliis is an important pathogen of freshwater teleosts occurring in both temperate and tropical regions throughout the world. The disease, ichthyophthiriosis, accounts for significant economic losses to the aquaculture industry, including the ornamental fish trade, and epizootics in wild fish populations can result in mass kills. This review attempts to provide a comprehensive overview of the biology of the parasite, covering the free-living and parasitic stages in the life cycle, host-parasite interactions, and the immune response of host and immune evasion strategies by the parasite. Emphasis on the immunological aspects of infection within the fish host, including molecular studies of i-antigens, reflects the current interest in this subject area and the quest to develop a recombinant vaccine against the disease. The current status of methods for the control of ichthyophthiriosis is discussed, together with new approaches in combating this important disease.
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Affiliation(s)
- R A Matthews
- School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK.
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Lobo-da-Cunha A, Azevedo C. The Golgi apparatus of the ciliated protozoon Ichthyophthirius multifiliis. Eur J Protistol 1994. [DOI: 10.1016/s0932-4739(11)80202-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Lobo-da-Cunha A, Azevedo C. Ultrastructural and cytochemical identification of peroxisomes in the ciliate Ichthyophthirius multifiliis. J Eukaryot Microbiol 1993; 40:169-71. [PMID: 8461889 DOI: 10.1111/j.1550-7408.1993.tb04899.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The peroxisomes of the parasitic ciliate Ichthyophthirius multifiliis were studied, using ultrastructural and cytochemical techniques. In this ciliate most peroxisomes possess a circular or oval section less than 0.6 micron in diameter. However, some dumbbell-shaped and elongated peroxisomes could also be observed. These organelles were frequently associated with the mitochondria and were more abundant in the cell cortex than in the center of the ciliate. Small vesicles and dense nucleoids were usually present in the ultrathin sections of these peroxisomes. Peroxisomal vesicles and tubular structures were selectively impregnated with osmium tetroxide. Catalase was detected by cytochemical techniques in I. multifiliis peroxisomes.
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Affiliation(s)
- A Lobo-da-Cunha
- Department of Cell Biology, University of Oporto, Porto, Portugal
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Schmahl G, Ruider S, Mehlhorn H, Schmidt H, Ritter G. Treatment of fish parasites. 9. Effects of a medicated food containing malachite green on Ichthyophthirius multifiliis Fouquet, 1876 (Hymenostomatida, Ciliophora) in ornamental fish. Parasitol Res 1992; 78:183-92. [PMID: 1589426 DOI: 10.1007/bf00931725] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
For systemic therapy against trophozoites of the skin-inhabiting stage of Ichthyophthirius multifiliis in ornamental fish, the latter were fed medicated food flakes containing malachite green once daily for 1-11 days ad libitum. Naturally or artificially infected cardinal tetras (Paracheirodon axelrodi), blue gouramis (Trichogaster trichopterus), or clown loach (Botia macracantha) were used in the trials. The fish were maintained in aerated 12.5- or 60-1 aquaria at 23 degrees C. Ultrastructural investigations (scanning and transmission electron microscopy) revealed clear deleterious effects of malachite green on the parasitic stages. Following the initial application, the inner membrane of the mitochondria was destroyed. In fish fed for 2 days, aggregation of the mucocysts and polymerization the microtubules within the macronucleus occurred. Finally, the trophozoite's membrane was completely destroyed. In fish fed for 4 days, the medicated food killed all trophozoites of I. multifiliis. Sensitive ornamental fish (e.g., P. axelrodi) showed no adverse effects after they had been fed with only the medicated food flakes for 2 months. Therefore, the oral administration of malachite green using this newly developed medicated food considerably reduces the risk of toxic effects on the fish hosts, which are sometimes caused by malachite green following its application by immersion therapy. The feeding of flakes medicated with malachite green provides and easy-to-handle and highly effective treatment of I. multifiliis in ornamental fish.
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Affiliation(s)
- G Schmahl
- Ruhr-Universität Bochum, Federal Republic of Germany
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Lobo-da-Cunha A, Azevedo C. Enzyme cytochemistry of the alveolar sacs and golgian-like cisternae in the ciliate Ichthyophthirius multifiliis. THE JOURNAL OF PROTOZOOLOGY 1990; 37:206-11. [PMID: 2162959 DOI: 10.1111/j.1550-7408.1990.tb01129.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In the cell cortex of the parasitic ciliate Ichthyophthirius multifiliis different kinds of cisternae were observed: the alveolar sacs, thick membrane cisternae and the endoplasmic reticulum. The thick membrane cisternae possess coated dilated rims and sometimes could be observed close to the endoplasmic reticulum. Using cytochemical techniques acid phosphatase, thiamine pyrophosphatase and nucleoside diphosphatase activities were detected in the thick membrane cisternae and in the alveolar sacs of trophozoites. In the endoplasmic reticulum acid phosphatase activity was not detected and only very small amounts of thiamine pyrophosphatase and nucleoside diphosphatase reaction product were observed. After exit from the host, a reduction in acid phosphatase activity was evident in the alveolar sacs. At theront stage acid phosphatase activity is absent from these structures. However, high thiamine pyrophosphatase and nucleoside diphosphatase activities remain in the alveolar sacs during the whole life cycle. On the other hand, acid phosphatase, thiamine pyrophosphatase and nucleoside diphosphatase activities were detected in thick membrane cisternae of theronts. Based on the morphological aspects and enzymatic content the thick membrane cisternae of the cell cortex are designated as golgian-like cisternae. The cytochemical results point out a relationship between the alveolar sacs and the Golgi complex.
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Affiliation(s)
- A Lobo-da-Cunha
- Department of Cell Biology, University of Oporto, Porto, Portugal
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Lobo-da-Cunha A, Azevedo C. Ultrastructural and cytochemical study of food vacuoles and primary lysosomes in Ichthyophthirius multifiliis (Ciliophora). Eur J Protistol 1988. [DOI: 10.1016/s0932-4739(88)80009-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Ewing MS, Kocan KM. Ichthyophthirius multifiliis (Ciliophora) exit from gill epithelium. THE JOURNAL OF PROTOZOOLOGY 1987; 34:309-12. [PMID: 3116222 DOI: 10.1111/j.1550-7408.1987.tb03181.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The first change in the sequence of morphological events occurring as fully developed Ichthyophthirius multifiliis trophonts spontaneously left gill epithelium or as younger trophonts departed, following experimentally induced death of the fish, was the separation of parasites from overlying host cells. Discharge of contractile vacuoles may have played a role in this process. Spaces then appeared between host cells, and individual epithelial cells became vacuolated. Finally, the epithelium ruptured and the parasites swam free. In induced exit after three days residence in the host, departure of the trophont was evident only after autolysis of epithelium had occurred. Induced departure of trophonts after four days residence was more rapid, suggesting an active role for the parasite in exit. Changes in parasite and epithelium observed in induced exit were similar to those in spontaneous departure after five days residence.
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Affiliation(s)
- M S Ewing
- Department of Zoology, Oklahoma State University, Stillwater 74078
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