Cnidaria Flashcards
What animals to the Cnidarian phylum comprise?
Jellies, anemones, corals, etc
What are some characteristics of Cnidarians?
Acoelomate, carnivores, sessile/drifting/motile, diverse range of body forms
Little is known of immunity/disease in Hydrozoa, Cubuzoa (box jelly), or Scyphozoa (moon n purple jelly), majority of work on Anthozoa (anemones, corals)
What is one explanation of the increase in number of described coral diseases?
Could be due to increased awareness/observation
What are some examples of coral diseases?
Black band disease, white pox disease, yellow band disease, aspergillosis, Sinularia tissue loss disease
What are the characteristics of black band disease?
1st noted in Belize, 1973, occurs globally, caused by bacterial consortium (cyanobacteria dominant)
Starts as a small patch, widening into rings formed by microbial mat
Ring migrates horizontally across coral
Tissue death thought to arise from bacterial sulphide production and anoxia
Also evidence that cyanobacteria from BBD consortium produce antimicrobial compounds displaying inhibitory activity against symbiotic coral bacteria
What are the characteristics of white pox disease?
In Florida and Caribbean, only affects Acropora palmata
Caused by Serratia marcescens, found in human and animal faeces
Disease produces lesions up to 80cm2 and can develop at any site over coral surface
Tissue loss is rapid
Highly contagious
What are the characteristics of yellow band disease?
Caribbean, affects 9 species, mostly Monastraea annularis
Causal agents: 4 species of Vibrio associated, also linked to increased water temperature
Lesions present at any site, but most commonly on upper surfaces
Tissue loss is slow
YBD-affected corals have ~40% less algal symbionts than healthy coral
What are the characteristics of aspergillosis?
Caribbean, mostly affects gorgonians e.g. Gorgonia ventalina
Mass mortalities observed in the 80s and 90s
Causal agent: Aspergillus sydowii, terrestrial species that can tolerate sea water, disease may be linked to land run-off
Aspergillus infects gorgonians after spore germination on coral surface, followed by penetration and spread of hyphae in coral tissue causing visible lesions
Sinularia tissue loss disease
A new disease of soft corals
Identified in corals from reefs in Guam
Starts as wrinkling in otherwise sm00th fingers, followed by tissue sloughing, necrosis and disintegration
Diseased tissue: signs of classic inflammatory response, increased numbers of amoebocytes
Diseased corals are more heavily predated upon by butterfly fish
How do the Cnidaria recognise pathogens?
There are few, if any, functional studies directly investigating this, but there is gene homology with TLRs, NLRs, and lectins
How do Cnidarians react to pathogens (cellular processes)?
Phagocytosis - demonstrated in amoebocytes isolated from the mesoglea of Actinia equina and in cells from the coenchyme of Swiftia exserta
Cytotoxicity - similar auto/allo-graft reactions to those of Porifera
Encapsulation - demonstrated in gorgonias, amoebocytes lay down melanin wall to prevent penetration of fungal hyphae. Recruitment of amoebocytes in infected gorgonians
Pro- and anti-apoptotic pathway genes identified (e.g. Bax, BIR)
How do Cnidarians react to pathogens (soluble effector molecules)?
Antibacterial and antifungal compounds, enzymes. Detection of complement factor C3, MAC, and perforin proteins reported from genomic data
ROS - demonstrated in amoebocytes isolated from the mesoglea of A. equina
What are the communication processes with Cnidaria?
(In mammalian complement there are 4 distinct reaction pathways, generated by at least 30 complement proteins. Complement factor C3 is vital in all 4 pathways)
1st record of molecular sequence for C3 below deuterostome level found in Swiftia in 2005
Sequences identified for membrane attack complexes (MAC) and perforin proteins
What is an example of marine natural product produced by Cnidaria and how does it work?
Pseudopterosins.
A phase II anti-inflammatory/analgesic
Represent a family of glycosides from the seawhip Pseudopterogorgia elisabethae
Some pseudopterosins recorded in vitro to have strong anti-TB, antiviral, anti-malarial, and anti-cancer activity
Inhibits phospholipase A2 and 5-lipoxygenase, enzymes involved in the arachidonic acid cascade of inflammation
This ultimately leads to prevention of eicosanoid synthesis, such as prostaglandins and leukotrienes (important in regulating inflammation)
Trial halted by lipophilicity and low solubility
More successful as a “cosmeceutical”: “extract” used to prevent skin irritation in various brands of cosmetics
Both recombinant technology and cell culture techniques are being developed in order to supply sufficient quantities
Draw out the summary Cnidaria
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