Miamiensis avidus

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Miamiensis avidus
Scientific classification
Domain:
Eukaryota
(unranked):
SAR
(unranked):
Alveolata
Phylum:
Ciliophora
Class:
Oligohymenophorea
Subclass:
Scuticociliatia
Order:
Philasterida
Family:
Parauronematidae
Genus:
Miamiensis
Binomial name
Miamiensis avidus
Thompson & Moewus, 1964 [1]

Miamiensis avidus is a species of unicellular marine eukaryote that is a parasite of many different types of fish. It is one of several organisms known to cause the fish disease scuticociliatosis and is considered an economically significant pathogen of farmed fish. [2] M. avidus is believed to be the cause of a 2017 die-off of fish and sharks in the San Francisco Bay. [3]

Contents

Taxonomy

M. avidus is a scuticociliate first described in 1964. [1] [4] It was discovered during a study originally aimed at investigating viruses of marine mammals, and was isolated from the bodies of seahorses collected from waters near Miami, Florida. The name of the genus refers to the University of Miami, where the first studies of the ciliate were performed, and the specific name avidus refers to its "greedy feeding habits". [1]

The name Philasterides dicentrarchi was originally applied to a similar ciliate identified as an infectious parasite in Mediterranean sea bass, [5] but is now recognized as a junior synonym of M. avidus. [6] [7] However, a recent study suggests they may in fact be distinct species. [8] The molecular phylogeny of scuticociliates is an active area of research. [9] [10]

Morphology

M. avidus cells are oval-shaped with a relatively pointed anterior end and a contractile vacuole toward the rounded posterior end of the cell. The cells feature several kineties, or rows of cilia along the major axis of the cell body, and a single caudal cilium. [1] [7] Descriptions vary on the number of kineties per cell, from as few as 10 [1] [8] to as many as 14. [7] [8] Each cell possesses one macronucleus and one micronucleus. [7] [8] The original 1964 description emphasized the significance of the morphology of the buccal apparatus and specialized oral cilia in differentiating among related ciliates. [1] Descriptions of these features differ subtly among one another and may differentiate M. avidus from closely related species. [7] [8] The life cycle [11] of M. avidus has been described and includes at least 3 stages: 1) Microstome, which mainly feeds on bacteria; 2) Macrostome, a voracious stage with a larger oral cavity which feeds on host tissues or other protozoans; and 3) tomite, a non-feeding, starvation-induced, smaller, dispersal stage. [12] The intricate sequence in the morphological microstome to macrostome transformation of M. avidus has been described. [11]

Ecological significance

Scuticociliates are free-living marine microorganisms that can function as opportunistic or facultative parasites. M. avidus infects a broad range of teleost species, as well as other groups of marine organisms such as seahorses, sharks, and crustaceans. [2] It is one of the best characterized of the group of scuticoliciates known to cause the fish disease scuticociliatosis, in which histophagous (tissue-eating) ciliates consume the blood, skin, and eventually internal organs of infected fish. The disease has an especially high mortality rate among flatfish, possibly due to their sedentary lifestyle involving high levels of skin contact between individuals. [2] In one comparative study, M. avidus infections spread further within host fish and had a significantly higher mortality rate than did similar scuticociliates. [13] Infections caused by M. avidus have been described in wild fish populations and in aquaculture, where it is an economically significant pathogen. [2] The species is believed to be responsible for a widely reported 2017 scuticociliatosis outbreak on the coast of Northern California, which saw thousands of dead fish and leopard sharks found in the San Francisco Bay. [3]

It is unclear what triggers free-living M. avidus to initiate infection. Experimental infections under laboratory conditions have produced varying results on the mechanism of infection; results in different conditions and with different host species vary in whether free-living ciliates can infect healthy fish or require an abraded or damaged skin surface. [2] Protease enzymes are commonly expressed by infectious parasites that damage host tissue, and are believed to play a role in M. avidus infections. [14] Transformation in M. avidus has been shown to be induced by a prey derived soluble factor, although its exact identity is unknown. [15]

Related Research Articles

<span class="mw-page-title-main">Litostomatea</span> Class of single-celled organisms

The Litostomatea are a class of ciliates. The group consists of three subclasses: Haptoria, Trichostomatia and Rhynchostomatia. Haptoria includes mostly carnivorous forms such as Didinium, a species of which preys primarily on the ciliate Paramecium. Trichostomatia (trichostomes) are mostly endosymbionts in the digestive tracts of vertebrates. These include the species Balantidium coli, which is the only ciliate parasitic in humans. The group Rhynchostomatia includes two free-living orders previously included among the Haptoria, but now known to be genetically distinct from them, the Dileptida and the Tracheliida.

<span class="mw-page-title-main">Predatory dinoflagellate</span>

Predatory dinoflagellates are predatory heterotrophic or mixotrophic alveolates that derive some or most of their nutrients from digesting other organisms. About one half of dinoflagellates lack photosynthetic pigments and specialize in consuming other eukaryotic cells, and even photosynthetic forms are often predatory.

Plagiopyla is a genus of ciliates. It includes nine species:

<i>Euplotes</i> Genus of single-celled organisms

Euplotes is a genus of ciliates in the subclass Euplotia. Species are widely distributed in marine and freshwater environments, as well as soil and moss. Most members of the genus are free-living, but two species have been recorded as commensal organisms in the digestive tracts of sea urchins.

Amoebophyra is a genus of dinoflagellates. Amoebophyra is a syndinian parasite that infects free-living dinoflagellates that are attributed to a single species by using several host-specific parasites. It acts as "biological control agents for red tides and in defining species of Amoebophrya." Researchers have found a correlation between a large amount of host specify and the impact host parasites may have on other organisms. Due to the host specificity found in each strain of Amoebophrya's physical makeup, further studies need to be tested to determine whether the Amoebophrya can act as a control against harmful algal blooms.

<span class="mw-page-title-main">Epixenosomes</span> Genus of bacteria

Epixenosomes, also known as Candidatus Epixenosoma, are a genus of bacteria in the phylum Verrucomicrobiota that form a symbiosis with marine ciliates of the genus Euplotidium, where they help to defend their ciliate hosts against predators. It is a monospecific genus, containing only the species Ca. Epixenosoma ejectans.

<i>Climacostomum</i> Genus of single-celled organisms

Climacostomum is a genus of unicellular ciliates, belonging to the class Heterotrichea.

Mesodinium chamaeleon is a ciliate of the genus Mesodinium. It is known for being able to consume and maintain algae endosymbiotically for days before digesting the algae. It has the ability to eat red and green algae, and afterwards using the chlorophyll granules from the algae to generate energy, turning itself from being a heterotroph into an autotroph. The species was discovered in January 2012 outside the coast of Nivå, Denmark by professor Øjvind Moestrup.

<span class="mw-page-title-main">Mobilida</span> Order of protists belonging to the ciliates phylum

Mobilida is a group of parasitic or symbiotic peritrich ciliates, comprising more than 280 species. Mobilids live on or within a wide variety of aquatic organisms, including fish, amphibians, molluscs, cnidarians, flatworms and other ciliates, attaching to their host organism by means of an aboral adhesive disk. Some mobilid species are pathogens of wild or farmed fish, causing severe and economically damaging diseases such as trichodinosis.

<span class="mw-page-title-main">Condylostoma</span> Genus of protists belonging to the ciliates phylum

Condylostoma is a genus of unicellular ciliate protists, belonging to the class Heterotrichea.

<span class="mw-page-title-main">Loxodidae</span> Family of protists

Loxodidae is a family of karyorelict ciliates.

<span class="mw-page-title-main">Armophorea</span> Class of single-celled organisms

Armophorea is a class of ciliates in the subphylum Intramacronucleata. . It was first resolved in 2004 and comprises three orders: Metopida, Clevelandellida, and Armophorida. Previously members of this class were thought to be heterotrichs because of similarities in morphology, most notably a characteristic dense arrangement of cilia surrounding their oral structures. However, the development of genetic tools and subsequent incorporation of DNA sequence information has led to major revisions in the evolutionary relationships of many protists, including ciliates. Metopids, clevelandellids, and armophorids were grouped into this class based on similarities in their small subunit rRNA sequences, making them one of two so-called "riboclasses" of ciliates, however, recent analyses suggest that Armophorida may not be related to the other two orders.

Scuticociliatia is a subclass of ciliates in the class Oligohymenophorea. Its members are called scuticociliates. These unicellular eukaryotes are microorganisms that are usually free-living and can be found in freshwater, marine, and soil habitats. Around 20 members of the group have been identified as causative agents of the disease scuticociliatosis, in which the ciliates are parasites of other marine organisms. Species known to be susceptible include a broad range of teleosts, seahorses, sharks, and some crustaceans.

<i>Licnophora</i> Genus of single-celled organisms

Licnophora is a genus of ciliates in the family Licnophoridae. They typically have an hourglass-like shape and live as ectocommensals on marine animals.

<i>Tracheloraphis</i> Genus of single-celled organisms

Tracheloraphis is a genus of ciliates in the family Trachelocercidae.

<i>Mesodinium</i> Genus of single-celled organisms

Mesodinium is a genus of ciliates that are widely distributed and are abundant in marine and brackish waters.

<i>Philasterides dicentrarchi</i> Species of single-celled organism

Philasterides dicentrarchi is a marine protozoan ciliate that was first identified in 1995 after being isolated from infected European sea bass reared in France. The species was also identified as the causative agent of outbreaks of scuticociliatosis that occurred between summer 1999 and spring 2000 in turbot cultivated in the Atlantic Ocean. Infections caused by P. dicentrarchi have since been observed in turbot reared in both open flow and recirculating production systems. In addition, the ciliate has also been reported to cause infections in other flatfishes, such as the olive flounder in Korea and the fine flounder in Peru, as well as in seadragons, seahorses, and several species of sharks in other parts of the world.

Scuticociliatosis is a severe and often fatal parasitic infection of several groups of marine organisms. Species known to be susceptible include a broad range of teleosts, seahorses, sharks, and some crustaceans. The disease can be caused by any one of about 20 distinct species of unicellular eukaryotes known as scuticociliates, which are free-living marine microorganisms that are opportunistic or facultative parasites. Scuticociliatosis has been described in the wild, in captive animals in aquariums, and in aquaculture. It is best studied in fish species that are commonly farmed, in which typical effects of infection include skin ulceration, hemorrhage, and necrosis, with post-mortem examination identifying ciliates in the skin, gills, blood, and internal organs including the brain.

Philasteridae is a family of ciliates in the order Philasterida.

Philasterides is a genus of ciliates in the order Philasteridae.

References

  1. 1 2 3 4 5 6 THOMPSON, JESSE C.; MOEWUS, LISELOTTE (August 1964). "Miamiensis avidus n. g., n. sp., a Marine Facultative Parasite in the Ciliate Order Hymenostomatida". The Journal of Protozoology. 11 (3): 378–381. doi:10.1111/j.1550-7408.1964.tb01766.x.
  2. 1 2 3 4 5 Jung, Sung-Ju; Woo, Patrick T.K. (2012). "Chapter 5: Miamiensis avidus and related species". In Woo, Patrick T.K.; Buchmann, Kurt (eds.). Fish parasites: pathobiology and protection . Wallingford, Oxfordshire: CABI. pp.  73-91. ISBN   9781845938062.
  3. 1 2 Shaban, Bigad; Witte, Rachel; Horn, Michael. "Thousands of Sharks, Other Sea Life Mysteriously Die in San Francisco Bay". NBC Bay Area. Retrieved 25 November 2017.
  4. ↑ Warren, A. (2009). "Miamiensis avidus Thompson & Moewus, 1964". WoRMS. World Register of Marine Species . Retrieved 24 November 2017.
  5. ↑ Dragesco, Armelle; Dragesco, Jean; Coste, Françoise; Gasc, Charles; Romestand, Bernard; Raymond, Jean-Christophe; Bouix, Georges (August 1995). "Philasterides dicentrarchi, n. sp., (ciliophora, scuticociliatida), a histophagous opportunistic parasite of Dicentrarchus labrax (Linnaeus, 1758), a reared marine fish". European Journal of Protistology. 31 (3): 327–340. doi:10.1016/S0932-4739(11)80097-0.
  6. ↑ "Miamiensis avidus (Ciliate) (Philasterides dicentrarchi)". UniProt Taxonomy. Retrieved 25 November 2017.
  7. 1 2 3 4 5 Jung, SJ; Kitamura, SI; Song, JY; Oh, MJ (18 January 2007). "Miamiensis avidus (Ciliophora: Scuticociliatida) causes systemic infection of olive flounder Paralichthys olivaceus and is a senior synonym of Philasterides dicentrarchi". Diseases of Aquatic Organisms. 73: 227–234. doi: 10.3354/dao073227 .
  8. 1 2 3 4 5 DE FELIPE, ANA-PAULA; LAMAS, JESÚS; SUEIRO, ROSA-ANA; FOLGUEIRA, IRIA; LEIRO, JOSÉ-MANUEL (29 May 2017). "New data on flatfish scuticociliatosis reveal that Miamiensis avidus and Philasterides dicentrarchi are different species". Parasitology. 144 (10): 1394–1411. doi:10.1017/S0031182017000749. hdl: 10261/177213 .
  9. ↑ Miao, Miao; Wang, Yangang; Li, Liqiong; Al‐Rasheid, Khaled A. S.; Song, Weibo (December 2009). "Molecular phylogeny of the scuticociliate, Philaster (Protozoa, Ciliophora), with a description of a new species, P. apodigitiformis sp. nov". Systematics and Biodiversity. 7 (4): 381–388. doi:10.1017/S1477200009990193.
  10. ↑ Gao, Feng; Katz, Laura A.; Song, Weibo (August 2012). "Insights into the phylogenetic and taxonomy of philasterid ciliates (Protozoa, Ciliophora, Scuticociliatia) based on analyses of multiple molecular markers". Molecular Phylogenetics and Evolution. 64 (2): 308–317. doi:10.1016/j.ympev.2012.04.008. PMID   22525941.
  11. 1 2 GÓMEZ-SALADIN, EDUARDO; SMALL, EUGENE B. (May 1993). "Oral Morphogenesis of the Microstome to Macrostome Transformation in Miamiensis avidus Strain Ma/2". The Journal of Eukaryotic Microbiology. 40 (3): 363–370. doi:10.1111/j.1550-7408.1993.tb04929.x.
  12. ↑ GÓMEZ-SALADÍN, EDUARDO; SMALL, EUGENE B. (November 1993). "Starvation Induces Tomitogenesis in Strain Ma/2". Journal of Eukaryotic Microbiology. 40 (6): 727–730. doi:10.1111/j.1550-7408.1993.tb04466.x.
  13. ↑ Song, JY; Kitamura, SI; Oh, MJ; Kang, HS; Lee, JH; Tanaka, SJ; Jung, SJ (12 February 2009). "Pathogenicity of Miamiensis avidus (syn. Philasterides dicentrarchi), Pseudocohnilembus persalinus, Pseudocohnilembus hargisi and Uronema marinum (Ciliophora, Scuticociliatida)". Diseases of Aquatic Organisms. 83: 133–143. doi: 10.3354/dao02017 .
  14. ↑ Seo, Jung Soo; Jeon, Eun Ji; Jung, Sung Hee; Park, Myoung Ae; Kim, Jin Woo; Kim, Ki Hong; Woo, Sung Ho; Lee, Eun Hye (2013). "Molecular cloning and expression analysis of peptidase genes in the fish-pathogenic scuticociliate Miamiensis avidus". BMC Veterinary Research. 9 (1): 10. doi: 10.1186/1746-6148-9-10 . PMC   3599101 . PMID   23311870.
  15. ↑ GOMEZ-SALADÍN, EDUARDO; SMALL, EUGENE B. (September 1993). "Prey-induced Transformation of Miamiensis avidus Strain Ma/2 by a Soluble Factor". The Journal of Eukaryotic Microbiology. 40 (5): 550–556. doi:10.1111/j.1550-7408.1993.tb06106.x.
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