High impact information on Cnidaria

• Here we describe the molecular characterization of members of the Wnt signalling pathway--Wnt, Dishevelled, GSK3, beta-Catenin and Tcf/Lef--in Hydra, a member of the evolutionarily old metazoan phylum Cnidaria [1].
• The Wnt signaling pathway plays essential roles in embryogenesis of higher eukaryotes from diploblastic, radially symmetrical cnidarians to mice and humans [2].
• Among those, homologs to forkhead, emx, aristaless, goosecoid, brachyury, wnt and nanos genes are regulated during apical patterning in cnidarians, suggesting that key components of early organizer activity were conserved across evolution and recruited for either anterior, axial, or dorso-ventral patterning in bilaterians [3].
• Cnidarians are among the simplest extant animals; however EST analyses reveal that they have a remarkably high level of genetic complexity [4].
• In contrast to known selenoproteins, SelJ appears to be restricted to actinopterygian fishes and sea urchin, with Cys homologues only found in cnidarians [5].

Biological context of Cnidaria

• Mitochondrial genes for cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 5 (ND5) of the sea anemone Metridium senile (phylum Cnidaria) each contain a group I intron [6].
• Introns were detected in the COI and ND5 genes of other sea anemones, but not in the COI and ND5 genes of other cnidarians [6].
• The mitochondrial genome of Acropora tenuis (Cnidaria; Scleractinia) contains a large group I intron and a candidate control region [7].
• Both the full COII DNA and protein sequences and a portion of the 16S rRNA gene were found to possess a striking similarity to published Cnidarian mtDNA sequences, allying the Porifera more closely to the Cnidaria than to any other metazoan phylum [8].
• Homeobox genes of the ANTP and PRD classes play important roles in body patterning of metazoans, and a large diversity of these genes have been described in bilaterian animals and cnidarians [9].

Associations of Cnidaria with chemical compounds

• We have identified and sequenced cDNAs encoding integrin beta subunits from a coral (phylum Cnidaria) and a sponge (Porifera), indicating that these proteins existed in the earliest stages of metazoan evolution [10].
• However, despite extensive research on photoproteins, there has been no evidence to indicate the origin of coelenterazine within the phylum Cnidaria [11].
• Amino acid assignments of metazoan mitochondrial codons AGA/AGG are known to vary among animal species; arginine in Cnidaria, serine in invertebrates and stop in vertebrates [12].
• We have clarified, for the first time, the spatiotemporal patterns of intracellular Ca(2+) increases at fertilization and the Ca(2+)-mobilizing mechanisms in eggs of hydrozoan jellyfish, which belong to the evolutionarily old diploblastic phylum, Cnidaria [13].
• In Cnidaria, the production of neurotoxic polypeptides is attributed to the ectodermal stinging cells (cnidocytes), which are discharged for offensive (prey capture) and/or defensive purposes [14].

Gene context of Cnidaria

• The evolutionary origin of the VEGF signalling pathway resides in the common ancestor of the Cnidaria and Bilateria [15].
• For example, homologs to the key developmental factor bone morphogenetic protein (BMP) 2 have been cloned by sequence identity from arthropods, mollusks, cnidarians, and nematodes [16].
• However, the T-box gene Brachyury could be isolated from sponges, placozoans and cnidarians [17].
• Here, we report the presence of VEGF and VEGFR homologous genes in a basal invertebrate of the phylum Cnidaria [15].
• Given the early divergence of Cnidarians during evolution, these studies indicate the highly conserved nature of laminin and provide additional information regarding the critical role of ECM components during hydra development [18].

Analytical, diagnostic and therapeutic context of Cnidaria

• Some of the ECM components known from vertebrates have been identified in cnidarians by immunohistochemistry, electron microscopy, rotary shadowing, biochemistry, and molecular cloning [19].

References