Diversity of the third form of complement, C3, in fish: functional characterization of five forms of C3 in the diploid fish Sparus aurata

We have recently shown that Sparus aurata, the gilthead sea bream (a diploid species), similarly to rainbow trout (a quasi-tetraploid species), possesses multiple forms of the third form of complement (C3). In the present study we have evaluated the ability of the gilthead sea bream proteins to function as active C3 molecules. All five C3 isoforms could be fixed covalently to sheep erythrocyte ghosts and were able to bind to various complement-activating surfaces in the presence of MgEGTA. In the absence of MgEGTA their binding capacities generally increased, presumably as a result of classical-pathway activation by the natural antibodies present in the serum. The presence of EDTA abrogated the binding of all C3 isoforms to the various surfaces tested. The C3 isoforms differed in the efficiency of their binding to complement-activating surfaces: the two most abundant C3 isoforms (C3-1 and C3-2) bound to zymosan as well as to sheep and rabbit erythrocyte ghosts, whereas C3-3, C3-4 and C3-5 were unable to bind to zymosan. Upon complement activation, all five C3 isoforms were cleaved to ‘iC3b’ by factor H and I-like proteins, generating fragments similar to those generated from C3 molecules of other species. Furthermore the degradation of methylamine-hydrolysed C3 isoforms to iC3b was significantly inhibited by EDTA. The structural and functional diversity that we have observed in the C3 isoforms of S. aurata would increase the capacity of this fish to recognize a broader spectrum of potential pathogens and reinforce a specific immune response, which in fish is delayed compared with that of higher vertebrates, and is based on a single Ig type (IgM).

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Specific Evolution and Gene Family Expansion of Complement 3 and Regulatory Factor H in Fish

Frontiers in Immunology ◽

10.3389/fimmu.2020.568631 ◽

2020 ◽

Vol 11 ◽

Author(s):

Babak Najafpour ◽

João C. R. Cardoso ◽

Adelino V. M. Canário ◽

Deborah M. Power

Keyword(s):

Complement System ◽

Sparus Aurata ◽

Factor H ◽

Gilthead Sea Bream ◽

Sea Bream ◽

Immune Gene ◽

Gene Repertoire ◽

Tandem Gene Duplication ◽

Hepatic Expression ◽

The Complement System

The complement system comprises a large family of plasma proteins that play a central role in innate and adaptive immunity. To better understand the evolution of the complement system in vertebrates and the contribution of complement to fish immunity comprehensive in silico and expression analysis of the gene repertoire was made. Particular attention was given to C3 and the evolutionary related proteins C4 and C5 and to one of the main regulatory factors of C3b, factor H (Cfh). Phylogenetic and gene linkage analysis confirmed the standing hypothesis that the ancestral c3/c4/c5 gene duplicated early. The duplication of C3 (C3.1 and C3.2) and C4 (C4.1 and C4.2) was likely a consequence of the (1R and 2R) genome tetraploidization events at the origin of the vertebrates. In fish, gene number was not conserved and multiple c3 and cfh sequence related genes were encountered, and phylogenetic analysis of each gene generated two main clusters. Duplication of c3 and cfh genes occurred across the teleosts in a species-specific manner. In common, with other immune gene families the c3 gene expansion in fish emerged through a process of tandem gene duplication. Gilthead sea bream (Sparus aurata), had nine c3 gene transcripts highly expressed in liver although as reported in other fish, extra-hepatic expression also occurs. Differences in the sequence and protein domains of the nine deduced C3 proteins in the gilthead sea bream and the presence of specific cysteine and N-glycosylation residues within each isoform was indicative of functional diversity associated with structure. The diversity of C3 and other complement proteins as well as Cfh in teleosts suggests they may have an enhanced capacity to activate complement through direct interaction of C3 isoforms with pathogenic agents.

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Stress effects of amyloodiniosis in gilthead sea bream Sparus aurata

Diseases of Aquatic Organisms ◽

10.3354/dao03199 ◽

2018 ◽

Vol 127 (3) ◽

pp. 201-211 ◽

Cited By ~ 3

Author(s):

M Moreira ◽

M Herrera ◽

P Pousão-Ferreira ◽

JI Navas Triano ◽

F Soares

Keyword(s):

Sparus Aurata ◽

Gilthead Sea Bream ◽

Sea Bream ◽

Stress Effects

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Ingestion of plastic and non-plastic microfibers by farmed gilthead sea bream (Sparus aurata) and common carp (Cyprinus carpio) at different life stages

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.146851 ◽

2021 ◽

Vol 782 ◽

pp. 146851

Author(s):

S. Savoca ◽

K. Matanović ◽

G. D'Angelo ◽

V. Vetri ◽

S. Anselmo ◽

...

Keyword(s):

Common Carp ◽

Cyprinus Carpio ◽

Sparus Aurata ◽

Gilthead Sea Bream ◽

Sea Bream ◽

Life Stages ◽

Common Carp Cyprinus Carpio ◽

Carp Cyprinus Carpio

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Experimental Horizontal Transmission of Enterospora nucleophila (Microsporea: Enterocytozoonidae) in Gilthead Sea Bream (Sparus aurata)

Animals ◽

10.3390/ani11020362 ◽

2021 ◽

Vol 11 (2) ◽

pp. 362

Author(s):

Amparo Picard-Sánchez ◽

M. Carla Piazzon ◽

Itziar Estensoro ◽

Raquel Del Pozo ◽

Nahla Hossameldin Ahmed ◽

...

Keyword(s):

Sparus Aurata ◽

Horizontal Transmission ◽

Infected Fish ◽

Gilthead Sea Bream ◽

Sea Bream ◽

Target Tissue ◽

Farmed Fish ◽

Infection Level ◽

Available Information

Enterospora nucleophila is a microsporidian enteroparasite that infects mainly the intestine of gilthead sea bream (Sparus aurata), leading to an emaciative syndrome. Thus far, the only available information about this infection comes from natural outbreaks in farmed fish. The aim of the present study was to determine whether E. nucleophila could be transmitted horizontally using naturally infected fish as donors, and to establish an experimental in vivo procedure to study this host–parasite model without depending on natural infections. Naïve fish were exposed to the infection by cohabitation, effluent, or intubated either orally or anally with intestinal scrapings of donor fish in four different trials. We succeeded in detecting parasite in naïve fish in all the challenges, but the infection level and the disease signs were always milder than in donor fish. The parasite was found in peripheral blood of naïve fish at 4 weeks post-challenge (wpc) in oral and effluent routes, and up to 12 wpc in the anal transmission trial. Molecular diagnosis detected E. nucleophila in other organs besides intestine, such as gills, liver, stomach or heart, although the intensity was not as high as in the target tissue. The infection tended to disappear through time in all the challenge routes assayed, except in the anal infection route.

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