Chordate

Chordate neurons (early Cambrian) As above plus first hydroxylations giving serotonin and dopamine iron/pterin chemistry in cytoplasm vesicle filled in centre of cell Recovery by amine oxidation (flavoenzymes)... 

Genomic structure Conserved (introns 1, 3 and 4) in the vertebrates and chordates No introns conserved with the known opsin families No introns conserved with the known opsin families... 

At higher levels of the tree of life, the hemichordates are peculiar for pyrazine steroidal alkaloids. In the chordates are the ascidians that give most alkaloids that are reminiscent of those isolated from... 

To the chordates, to Amphioxus This book is also dedicated to those ... 

As mentioned earlier, marine animals are the richest source of various biologically and biomedically important compounds/materials/sub-stances. One such traditional and ancient medicinally important chordate... 

Satoh, N. and Jeffery, W. R. (1995). Chasing tails in ascidians Developmental insights into the origin and evolution of chordates. Trends Genet. 11, 354-359. 

Pavao, M. S. (2002). Structure and anticoagulant properties of sulfated glycosaminoglycans from primitive Chordates. An. Acad. Bras. Cien. 74,105-112. 

Echinoderms constitute a peculiar phylum of invertebrates belonging to the most highly organized animals, the Deuterostomia, including, also, all the phyla of chordates. Among the invertebrates, echinoderms are the richest in glycolipids, and differ from all of the other marine invertebrate phyla in that they contain sialoglycolipids.79 This conforms to the data of Warren, who studied the occurrence of sialic acids in Nature, and found that all of the vertebrates have them, but, of the invertebrates, only the echinoderms practically all of the Protostomia contain no sialic acids.274... 

Tunicates constitute one of the most amazing groups of marine animals, close to chordates, whose larvae stand higher, by a number of important features, than the adult forms. Together with the other chordates and echinoderms, tunicates belong to the Deuterostomia. 

However, the presence of specific glycolipids, the sialoglycolipids, seems to be directly associated with the evolutionary position of the animal. Sialoglycolipids, found in all vertebrates, have also been found in echinoderms, which, together with vertebrates and the other chordates,... 

Rowe, T. (2004) Chordate phylogeny and development. In Cracraft, J. and Donoghue, M.J. (eds) Assembling the Tree of Life. Oxford University Press, Oxford, UK, pp. 384 )09. 

Holland ND, Clague DA, Gordon DP, Gebruk A, Pawson DL, Vecchione M (2005) Lophenteropneust Hypothesis Refuted by Collection and Photos of New Deep-Sea Hemi-chordates. Nature 434 374... 

Riemer, D., Karabinos, A., and Weber, K. (1998). Analysis of eight cDNAs and six genes for intermediate filament (IF) proteins in the Cephalochordate Branchiostoma reveals differences in the IF multigene families of lower chordates and the vertebrates. Gene 211, 361-373. 

The glycolipids of the testis of a number of animals have been analysed to determine whether SGG is a universal constituent of testicular tissue of all chordates. The results of these studies are summarized in Table III. 

Two other points arising from this line of work also deserve brief discussion. Firstly, it is relevant to mention that sulfo-quinovosyl diglyceride has been reported to be the major glyco-lipid of the spermatozoa of sea urchins (58). It will thus be of interest to extend studies of the comparative biochemistry of testicular glycolipids to lower classes of animals as well as to further members of the classes listed in Table III. Secondly, it is apparent that, whatever the precise phylogenetic distribution of glycolipids in testis may turn out to be, the results to date strongly support the hypothesis that sulfatides play an important role in testicular and/or spermatozoal function in chordates. 

The Hemichordata are a phylum of lower deuterostomes and, therefore, are more closely related to echinoderms and chordates than to annelids. They are discussed here because they are separate lineages that have evolved distinctive metabolites and also because of their feeding mechanisms. Very little work has been done on their natural products, however. 

King, G. M., Inhibition of microbial activity in marine sediments by a bromophenol from a hemi-chordate, Nature, 323, 257, 1986. 

Many marine species also possess the tyrosinase-mediated pathway to synthesize the UV-absorbing pigment melanin. Melanin occurs in a wide range of taxa including bacteria, fungi, invertebrates, and chordates. While much is known about the role of melanin in the UV protection of mammalian skin, very little research has been conducted to examine the efficiency of melanin as a UV-protective mechanism in aquatic taxa.9 It is known that melanin levels in juvenile hammerhead sharks, Sphyrna lewini, are directly correlated to solar UV exposure in the freshwater crustacean Daphnia pulex, melanin concentrations are genetically determined within populations and are correlated to UV sensitivity.50-51 The few studies that have been undertaken suggest that melanin has an important role in UV protection in aquatic environments. 

FIGURE 15.7 Phylogenetic distribution of MAAs by percent occurrence in individual species within algal (this category includes photosynthetic prokaryotic taxa indicated in Table 15.2), invertebrate, and chordate groups (see Table 15.2 for reference citations and groups included in these categories X = percent values for all taxa and all MAAs combined). 

MAAs have not been studied as extensively in freshwater as in marine species, but these compounds have been reported in freshwater cyanobacteria, microalgae, invertebrates, and chordates (fish).106 116 130-133 There may be several MAAs unique to freshwater organisms. Aqueous extracts from the cyanobacterium Nostoc commune contain a mixture of UV-absorbing compounds with two distinct chromophores that have maximum absorbance at 312 and 335 nm.134 135 These compounds are comprised of the usual mycosporine cyclohexenone ring structure however, it is... 

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