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It is to be hoped that the urgent need for new strategies in cancer research or for new candidates for antibiotics in view of the fast development in resistance of harmful bacteria will lead to a renaissance in the field. After all, the potential rewards are of considerable magnitude. Nature — Alender CB A biologically active substance from spines of two diadematid sea urchins. Luminescence — Deheyn D, Mallefet J, Jangoux M Cytological changes during light production process in dissociated photocytes from the ophiuroid Amphipholis squamata Echinodermata.
Comp Biochem Physiol —43 6 C. Petzelt Lin W, Zhank H, Beck G Phylogeny of natural cytotoxicity: cytotoxic activity of coelomocytes of the purple sea urchin, Arbacia punctulata. Eine oekologische Katatrophe. Naturwiss Rdschau — Mebs D A myotoxic phospholipase A2 from the crown-of-thorn starfish Acanthaster planci. J Biotechnol — Nakagawa J, Kimura A Partial purification of a toxic substance from pedicellariae of the sea urchin Toxopneustes pileolus.
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Comparison between the regular, repetitive, and linear fucans from echinoderms with the more heterogeneous and branched polymers from brown algae. Comp Biochem Physiol Biochem Mol Biol — Yamada K Chemo-pharmaceutical studies on the glycospingolipid constituents from echinoderm, sea cucumbers, as the medicinal materials.
- Progress in Molecular and Subcellular Biology.
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Matranga Abstract. In this chapter, we summarise fundamental findings concerning echinoderms as well as research interests on this phylum for biomedical and evolutionary studies. We discuss how current knowledge of echinoderm biology, in particular of the sea urchin system, can shed light on the understanding of important biological phenomena and in dissecting them at the molecular level.
The general principles of sea urchin embryo development are summarised, mainly focusing on cell communication and interactions, with particular attention to the cell—extracellular matrix and cell—cell adhesion molecules and related proteins. Our purpose is not to review all the work done over the years in the field of cellular interaction in echinoderms. On the contrary, we will rather focus on a few arguments in an effort to re-examine some ideas and concepts, with the aim of promoting discussion in this rapidly growing field and opening new routes for research on innovative therapeutic tools.
The phylum, characterised by the great morphological variety of its members, belongs to a branch of the animal kingdom known as deuterostomes. The Echinodermata have been extensively studied, particularly because of some aspects such as the ample fossil record extending back to the Precambrian, their ecological importance in the marine environment, the interesting mor- F.
Zito et al. A Living fossil, the pencil urchin Eucidaris tribuloides. B Presumptive crinoid fossil found in , in the Black Forest, Germany phology of adult organisms and the advantage of experimentally manipulable embryos. Approximately 13, echinoderm fossil species are known Fig. The body is oriented with the mouth facing up and they may or may not have a stalk.
The class includes about 2, living species. Some of them have bilateral symmetry, which occurred secondarily during evolution. About 1, living species are known. The Concentricycloidea sea daisies , with only two species, is an enigmatic group of echinoderms whose phylogenetic position remains elusive, although evidence suggests a relationship with asteroids Pearse and Pearse The phylogenetic relationships among the five classes have been extensively controversial, but it seems generally accepted that the class of Crinoidea branched first and that the Echinoidea and Holothuroidea are sister clades Fig.
Although the main character of the body plan of adult echinoderms, the pentamerous symmetry, led the father of palaeontology, George Cuvier — , to place them in the Radiata phylum, it is now widely accepted Cell Adhesion and Communication: A Lesson from Echinoderm Embryos 9 Fig.
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Hypothetical phylogenetic tree of the five living classes of Echinodermata. This hypothesis, predicting that the Crinoidea branched earlier than the other classes and suggesting that the Echinoidea and Holothuroidea are sister clades, was first proposed by Bather and is supported by morphological and molecular evidence. Littlewood et al. Among marine invertebrates, in fact, the echinoderm clade has a unique position in the evolutionary tree: during evolution it first appeared in the Metazoa phylum with features of deuterostomes, in direct evolutionary line with chordates and vertebrates, thus implying that there is less divergence between echinoderms and vertebrates than between echinoderms and other invertebrates.
This is not surprising since, although the two phyla appear so dissimilar, molecular data and fossil records strongly support this grouping, even if the attempts to identify a common ancestor are highly speculative. Actually, it is becoming clearer that the genes encoding developmental regulatory proteins already identified in other phyla, the modified interactions among them and changes in their expression patterns are at the basis of the evolution of animal morphology Raff ; Wray and Lowe The name echinoderm is derived from the Greek word meaning spiny skin and it has been the original denomination for sea urchins, since spines are their main external characteristic.
Echinoderms are exclusively marine invertebrates and, with a few exceptions, are all benthic organisms bottomdwellers. A number of lifestyles are typical among different classes, e. Echinoderms usually have separate sexes with no evident sexual dimorphism. Reproduction is typically achieved by external fertilisation, with eggs and sperm freely released into the seawater.
The life cycle is usually complex. In most echinoderms the embryo develops into a planktonic larva with a bilateral symmetry, that in some species goes through metamorphosis, typically radical, before reaching the final adult morphology.
There are some features that make echinoderms so interesting to study. First, their sensitivity to environmental changes in seawater ecosystems. It is well known that the disappearance of fragile species from certain geographic areas is in direct relationship with high contamination of seawater and sedi- Cell Adhesion and Communication: A Lesson from Echinoderm Embryos 11 ments, and echinoderms are one such fragile species.
In particular, embryos, juveniles and adults of the classes Echinoidea and Asteroidea are well utilised in studies on marine pollution, since they highly resent it. Second, their ability to regenerate parts of the body particularly Ophiuroidea and Asteroidea , based on stem cell recruitment. This phenomenon makes a fundamental contribution to the adaptive capacities of the whole species. Third, their ability to cause remarkable transformations in submarine substrates.
Since the echinoderms are one of the most important marine invertebrates that do not feed on filtration, as they graze on substrate except for holothurians and crinoids , they can induce changes in the ratios and distributions of other marine species fishes and others , and eventually cause segregation as well as speciation. These three features of echinoderms are just some examples of the huge number of ways in which echinoderms can be of help in the understanding of important biological phenomena, and in dissecting them at the molecular level.
Few people realise that research on simple marine organisms has led to some of our greatest medical advances, as well as to new insights into environmental pollution. One of the advantages of using echinoderms is that they produce thousands of virtually identical embryos, and that the morphological abnormalities are readily visualised in the live organism under the light microscope. In the following text, some aspects of the medical advances achieved from such studies will be briefly outlined.
One example is the screening for the toxicity caused by retinoids utilised in dermatological practice, since it has been shown that foetal malformation is a major form of toxicity associated with some of them Kahn et al. The sea urchin embryo has also been used as a model for screening for suspected mammalian developmental neurotoxicants and for anticancer drug testing Nishioka et al. This test system is applicable also for exami- 12 F. Interestingly, a method has been developed to study the invasive properties of metastatic cells and to test the differential effects of anti-tumoural substances on their invasive capacity, which makes use of the sea urchin embryo basement membrane Livant et al.
This structure is selectively permeable and can be obtained intact with the associated extracellular matrix ECM from sea urchin embryos Livant et al. It has been demonstrated that all metastatic tumour cells placed in contact with these basement membranes were able to invade them and the invasion was rapid and efficient; on the other hand, as expected, non-metastatic cells failed in the invasion.
These results suggest that molecules participating in basement membrane recognition and invasion have been functionally conserved during evolution and that their constitutive activity may allow metastatic cells to escape their tissues of origin Livant et al. For example, it has been shown that novel polysaccharides present on echinoderm surfaces seem able to stimulate early host defence and microbial clearance, but not the later phases of inflammatory tissue injury associated with sepsis.
These are the most promising alternative or integrative treatments for pneumonia that are under development Cazzola et al. In the last 10 years, a number of molecules with different effects on mammalian cells have been purified from echinoderms. Other compounds display considerable cytotoxicity against a small panel of human solid tumour cell lines, such as polyhydroxysterols and saponins isolated from the sea star Wang et al. The latter compounds have been suggested as useful drugs for cancer chemotherapy. Recently, Meijer and Raymond have reviewed the steps that lead to the identification of new drugs; that are now under evaluation for therapeutic use against cancer, neurodegenerative diseases and cardiovascular disorders.
This is an example of how results obtained from basic research, i. From the first inhibitors discovered, a more selective one was optimised, which is now entering phase II clinical trials against cancers and phase I clinical tests against glomerulonephritis Meijer and Raymond A sea urchin gene showing very strong sequence and structural homology with the gene coding for dystrophin, which is defective in Duchenne muscular dystrophy, has been identified. The partial characterisation of this gene helped in the construction of an evolutionary tree connecting the vertebrate dystrophin gene family with related genes in invertebrates Wang et al.
A novel protein homologue to the sea urchin fascin an actin-bundling protein has been found to be over-expressed in pancreatic ductal adenocarcinoma, suggesting its use as a tumour marker with potential diagnostic and therapeutic implications for pancreatic carcinoma Maitra et al. Sea urchin sperm homologues of polycystin-1 and polycystin-2, the proteins mutated in autosomal-dominant polycystic kidney disease, have been sequenced Mengerink et al.
Both proteins have been shown to co-localise exclusively to the plasma membrane over the sperm acrosomal vesicle, where they may function as a cation channel mediating the sperm acrosome reaction. These data provide the first suggestion for the role of a polycystin-1 protein in a specific cellular process Mengerink et al.
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Recently, a fasciclin-I-like protein has been purified from sea urchin ovaries and, by in vitro assays, it has been shown to be active in promoting HT human fibrosarcoma cell attachment Sato et al. Fasciclin-I is a neuronal cell adhesion molecule and up to now various proteins belonging to the family have been identified in different species, including bacteria, plants and vertebrates, and in the sea urchin embryo and eggs Brennan and Robinson ; Wessel et al.
However, latest findings indicate that the protein is highly conserved in evolution and suggest important biological roles Sato et al. There are also examples of the isolation of new human genes whose function has been hypothesised on the basis of their high homology to already known and characterised echinoderm genes. A novel human homologue of the gene coding for echinoderm microtubule-associated protein EMAP has been isolated from a locus of Usher syndrome type 1, an autosomal recessive genetically heterogeneous disorder.
The finding of its high level of homology to the echinoderm cytoskeletal component EMAP, especially at the micro- 14 F. Its study is becoming essential for the comprehension of any other fields in biology, since it combines molecular and cellular biology, physiology, anatomy, immunology, research on cancer and also evolution and ecology. Development is mainly devoted to the production and organisation of all the different cellular types constituting the adult organism. The generation of different types of cells is a process known as differentiation, while the organisation of differentiated cells in tissues and organs is performed during morphogenesis.
It is well known that cells do not behave as single entities, but rather their association in multicellular structures requires precise co-ordination between release and uptake of signals. Communication and interaction among living cells are, in fact, fundamental events required for the proper development of tissues and organs. Living cells continuously receive inputs from the environment and modify their behaviour throughout a complex network of signalling pathways.