Tunic Phagocytes Are Involved in Allorejection Reaction in the Colonial Tunicate <i>Aplidium yamazii</i> (Polyclinidae, Ascidiacea)

Ishii, Teruhisa; Hirose, Euichi; Taneda, Yasuho

doi:10.2307/25066671

Cited by 10 publications

(22 citation statements)

References 25 publications

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“…Hemocytes include spreading and round phagocytes, always present, cytotoxic granulocytes, widely found, and other cell types in some particular taxa, such as net cells and cells storing acid or pigments (8, 17–21), all contributing to protect the organism from predators, pathogens, or parasites. Phagocytes ingest foreign cells having entered the tunic (17, 22), and tunic phagocytes are the main effectors of allorecognition in the colonial species Aplidium yamazii (23). Granulocytes frequently contain and release antimicrobial peptides (24) and the enzyme phenoloxidase (PO) (25).…”

Section: The Sites Of Immune Responsesmentioning

confidence: 99%

Immunity in Protochordates: The Tunicate Perspective

Franchi

Ballarin

2017

Front. Immunol.

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Tunicates are the closest relatives of vertebrates, and their peculiar phylogenetic position explains the increasing interest toward tunicate immunobiology. They are filter-feeding organisms, and this greatly influences their defense strategies. The majority of the studies on tunicate immunity were carried out in ascidians. The tunic acts as a first barrier against pathogens and parasites. In addition, the oral siphon and the pharynx represent two major, highly vascularized, immune organs, where circulating hemocytes can sense non-self material and trigger immune responses that, usually, lead to inflammation and phagocytosis. Inflammation involves the recruitment of circulating cytotoxic, phenoloxidase (PO)-containing cells in the infected area, where they degranulate as a consequence of non-self recognition and release cytokines, complement factors, and the enzyme PO. The latter, acting on polyphenol substrata, produces cytotoxic quinones, which polymerize to melanin, and reactive oxygen species, which induce oxidative stress. Both the alternative and the lectin pathways of complement activation converge to activate C3: C3a and C3b are involved in the recruitment of hemocytes and in the opsonization of foreign materials, respectively. The interaction of circulating professional phagocytes with potentially pathogenic foreign material can be direct or mediated by opsonins, either complement dependent or complement independent. Together with cytotoxic cells, phagocytes are active in the encapsulation of large materials. Cells involved in immune responses, collectively called immunocytes, represent a large fraction of hemocytes, and the presence of a cross talk between cytotoxic cells and phagocytes, mediated by secreted humoral factors, was reported. Lectins play a pivotal role as pattern-recognition receptors and opsonizing agents. In addition, variable region-containing chitin-binding proteins, identified in the solitary ascidian Ciona intestinalis, control the settlement and colonization of bacteria in the gut.

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Section: The Sites Of Immune Responsesmentioning

confidence: 99%

Immunity in Protochordates: The Tunicate Perspective

Franchi

Ballarin

2017

Front. Immunol.

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“…Remarkably, when different Botryllus colonies are brought into contact, a strong self-nonself reaction is provoked that results in cell clumping at the sites of contact (Oren et al, 2008;Saito et al, 1994). Cell aggregation as allogeneic response, was also reported in the colonial ascidian Aplidium (Ishii et al, 2008).…”

Section: Discussionmentioning

confidence: 67%

Ultrastructural aspects of naturally occurring wound in the tunic of two ascidians: Ciona intestinalis and Styela plicata (Tunicata)

Bella

Carbone

Leo

2015

Micron

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a b s t r a c tEfficient wound healing is essential for all animals from insects to mammals. Ciona intestinalis and Styela plicata are solitary ascidians belonging to urochordates, a subphylum that occupies a key phylogenetic position as it includes the closest relative to vertebrates. Urochordate first physical barrier against invaders is the tunic, an extracellular matrix that is constantly exposed to all kinds of insults. Thus, when damage occurs, an innate immune response is triggered to eliminate impaired tissue and potentially pathogenic microbes, and restore tissue functionality. Ultrastructural aspects of the tunic in the wound healing process of two ascidians are described. In the injured areas, we evidenced thinning of the tunic and areas of low fibre density, dense intratunic bacterial and protozoan population, and inflammatory aspects such as the increase in tunic cells, their aggregates, and phagocytosis. This is the first report on tunic physical wounding occurring in the natural habitat.

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“…; Ishii et al. ). Functionally, phagocytes are scavenging cells, engulfing cellular debris, foreign or dead matter, and zooid fragments.…”

Section: Discussionmentioning

confidence: 98%

“…To date, cellular events in aplousobranch allorecognition have been described for three species (Bishop & Sommerfeldt ; Ishii & Hirose ; Ishii et al. ; Dias & Yokoyama ). Here, we contributed information on different cell types, and their abundance and distribution patterns during CAAs and CIAs for an additional aplousobranch species.…”

Section: Discussionmentioning

confidence: 99%

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Tunic cell populations during fusion events in the colonial ascidian Didemnum vexillum (Tunicata)

Sellers

Fagerberg

Litvaitis

2013

Invertebrate Biology

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We documented changes in the abundance and distribution patterns of tunic cells involved in the allorecognition response of the colonial aplousobranch Didemnum vexillum, whose zooids do not share a common vascular system. A histological examination of the fusion zone of isogeneic (CIAs) and allogeneic (CAAs) fused colony assays revealed that tunic cuticles were rapidly regenerated. The underlying tunic matrix fused readily in all assays and controls. We identified four different types of tunic cells. Phagocytic cells represented the most abundant cell type in allogeneic fusions, followed by morula cells. These cells were more abundant at the immediate fusion junction than at 120 lm or 240 lm from the junction, most likely because they mediate the allorecognition reaction. Elongated filopodial cells also were present, although only at very low abundances, and a layer of bladder cells was located immediately below the cuticle. Our results provide quantitative evidence for the involvement of tunic cells in the allorecognition response of a highly invasive ascidian.

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Tunic Phagocytes Are Involved in Allorejection Reaction in the Colonial Tunicate Aplidium yamazii (Polyclinidae, Ascidiacea)

Cited by 10 publications

References 25 publications

Immunity in Protochordates: The Tunicate Perspective

Immunity in Protochordates: The Tunicate Perspective

Ultrastructural aspects of naturally occurring wound in the tunic of two ascidians: Ciona intestinalis and Styela plicata (Tunicata)

Tunic cell populations during fusion events in the colonial ascidian Didemnum vexillum (Tunicata)

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