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PubMed2003

[Diversity and distribution of crustaceans and echinoderms and their relation with sedimentation levels in coral reefs].

Seven reef formations were studied in South Caicos, Turks & Caicos, to determine the species richness, patterns of diversity and patterns of distribution of crustaceans and echinoderms, and to evaluate the relationship between these parameters and the degree of sedimentation of the different sites. The reefs showed a gradient from a high sedimentation level, almost totally covered by algae, to places with no sediment particles deposited over the corals. Sites were classified as with high, low or null sedimentation, and species richness, abundance, diversity, spatial distribution of species and similarity among sites were estimated. No unique pattern was found: for crustaceans as well as for echinoderms, the site with the highest diversity value and high equitability, presumably associated to the environmental heterogeneity of this reef formation, showed null sedimentation and an uniform and random pattern of distribution, crustaceans and echinoderms respectively. The two sites with the lowest diversity for both animal groups, although with different sedimentation levels, showed the lowest equitability value and were the only sites with an aggregated pattern of distribution. The next sites in diversity for crustaceans were those with high sedimentation, probably because most species present inhabit empty conchs, in the sediment, or among seagrass. For the echinoderms, on the contrary, the intermediate sites in diversity had low sedimentation; the habitat requirements for these species (inside sponges, over the corals or among rocks) may have determined this result. The sites with lowest diversity had high sedimentation levels. In these, crustaceans showed the lowest equitability values and an aggregated spatial distribution, while the community of echinoderms was dominated by one single species. Although only general descriptions can be elucidated with the present results, knowledge about the basic population characteristics and natural history of these reef communities, combined with that of the perturbations related to human activities, provides useful base information for appropriate planning for the restoration and conservation of this ecosystem.

Animals↗
PubMed1981

Biocompatibility of echinoderm skeleton with mammalian cells in vitro: preliminary evidence.

The physical and chemical properties of echinoderm skeleton are reviewed. A method is described for preparing cell-free, sterile echinoderm skeletal plates (ossicles) which were used as porous substrates for cell cultures. Ossicles of the starfish Pisaster ochraceus were evaluated as substrates for the culture of three mammalian cell lines. Each line grew vigorously on ossicles, and fibroblasts quickly infiltrated their porous microstructure. Echinoderm skeletal plates provide a simple, convenient alternative to coverslips and porous membranes for SEM or correlated SEM/TEM studies of cell behavior. More importantly, the preliminary evidence for biocompatibility presented suggests that native echinoderm skeleton has potential use as a biomaterial and, because of its microstructure and relative solubility; deserves evaluation as a kind of biodegradable ceramic.

Animals↗
PubMed2001

Regeneration in echinoderm larvae.

The ability of echinoderms to regenerate missing body parts has been a subject of interest to scientists for many years. Asexual reproduction (by fission or budding) is a phenomenon that involves regeneration of missing structures. Although asexual reproduction and regeneration have been the focus of many studies in adult echinoderms, there have been comparatively fewer studies examining these phenomena in echinoderm larvae, and most of these have been conducted in the last few years. In this article we review regeneration in larval echinoderms. We also discuss larval asexual reproduction.

Animals↗
PubMed1993

Invertebrate cytokines. III: Invertebrate interleukin-1-like molecules stimulate phagocytosis by tunicate and echinoderm cells.

Phagocytosis is the predominant defense mechanism of invertebrates. Here we show that phagocytosis by echinoderm bladder amoebocytes and tunicate granular amoebocytes can be enhanced by invertebrate interleukin-1-like molecules. As little as 5 ng/ml of invertebrate interleukin-1 produced a significant stimulation of echinoderm and tunicate amoebocyte phagocytosis. Stimulation of phagocytosis by echinoderm interleukin-1-like molecules was inhibited by antisera to vertebrate interleukin-1. Invertebrate interleukin-1 also acted as an opsonin when preincubated with erythrocytes or yeast. In addition, the cellular mechanisms of invertebrate phagocytosis were studied using pharmacologic agents to inhibit echinoderm amoebocyte phagocytosis. The energy requirements and involvement of cellular cytoskeletal elements in phagocytosis by bladder amoebocytes were similar to those of mammalian macrophages. These results demonstrate a role for interleukin-1 in invertebrate host defense mechanisms.

Animals↗
PubMed2005

Bioresources from echinoderms.

More than 6,500 species have been recorded in the phylum Echinodermata. A variety of biologically active substances have been isolated from the echinoderm species: saponins, glycolipids, carotenoids, porphyrins, naphthoquinones, venoms and others. Several substances unique to the echinoderm have also been reported and some of them showed high potentiality as a new medicament. This chapter gives an overview of the history of the exploitation of echinoderm species in the Orient, presents studies on the biologically active substance obtained from them, and discusses questions related to the exploitation of the echinoderm and prospects of development of new medications.

Animals↗
PubMed2005

Echinoderm reactive oxygen species (ROS) production measured by peroxidase, luminol-enhanced chemiluminescence (PLCL) as an immunotoxicological tool.

The importance of reactive oxygen species (ROS) production in invertebrate immunity prompted the use of this response in immunotoxicological studies in several taxa including marine organisms. In this chapter, we review the effects of environmental factors and contaminants such as heavy metals and polychlorinated biphenyls (PCBs) on the production of ROS by the main immune effector cells of echinoderms, the so-called amoebocytes. ROS production was measured by the peroxidase, luminol-enhanced chemiluminescence (PLCL) method. This method was found to predominantly reflect the production of superoxide anions and peroxides, among which hydrogen peroxide and peroxynitrite are the main species detected. Exogenous factors such as water temperature and salinity can influence this immune response in echinoderms. However, gender, handling stress and parasitism by a castrating ciliate apparently did not affect it. The impact of metals on ROS production differed greatly according to the duration and routes of exposure; in vitro and short-term in vivo exposures to metals caused an inhibition of this immune response, while the opposite effect was observed in a long-term in vivo exposure study. On the other hand, PCBs systematically had a stimulatory effect on ROS production independent of the echinoderm species or exposure routes. From the study of complex field contaminations, it appeared that contaminants released in the environment, such as metals, modulate starfish amoebocyte ROS production. This impact potentially represents a threat to the sustainability of natural populations of echinoderms and thereby to the stability of benthic ecosystems.

Allergy and Immunology↗
PubMed2000

Ammonium and phosphate excretion in three common echinoderms from Philippine coral reefs.

The ammonium and phosphate excretion and oxygen consumption of three species of echinoderms (Tripneustes gratilla, Protoreaster nodosus and Ophiorachna incrassata) commonly encountered in Philippine coral reefs were investigated in relation to time of day (i.e. daytime between 10:00 and 12:00 h vs. nighttime between 22:00 and 24:00 h) and their recent feeding history (i.e. recently-collected vs. short-term starvation for 3+/-1 days). The experiment used whole organism incubations and followed a nested hierarchical design. Ammonium excretion rates were 1447+/-310 nmolg(-1) DWh(-1) (mean+/-S.E., n=24) for T. gratilla, 361+/-33 for O. incrassata and 492+/-38 for P. nodosus. Ammonium excretion differed significantly among species, time of incubation and recent feeding history. Interaction between species and recent feeding history was also significant. The organisms excreted more ammonium during daytime except for starved specimens of O. incrassata. In addition, animals that were starved in the laboratory for a few days had a tendency to excrete more ammonium than recently-collected specimens. Phosphate excretion rates were 25+/-13 nmolg(-1) DWh(-1) for T. gratilla, 10+/-2 for O. incrassata and 4+/-1 for P. nodosus. There were no significant differences in phosphate excretion among the three species of echinoderms, their recent feeding history and time of day. Oxygen consumption rates were 286+/-24 µg O(2)g(-1) DWh(-1) for T. gratilla, 64+/-3 for O. incrassata and 54+/-3 for P. nodosus. Oxygen consumption differed significantly among species and recent feeding history but differed only slightly with time of incubation. There was a significant correlation between oxygen consumption and ammonium excretion (r=0.48, P=0.018), and between oxygen consumption and phosphate excretion (r=0.41, P=0.047) for T. gratilla. The nutrient excretion by tropical echinoderms is another pathway by which inorganic nutrients are regenerated in coral reef communities. However, the quantity of nutrients excreted is dependent on the species of echinoderms, their nutritional status and time of day.

Journal Article↗
PubMed1998

Preliminary observations on ascidian and echinoderm neurons and neural explants in vitro.

As part of a study on echinoderm and ascidian neural regeneration, attempts were made to develop a system for the maintenance of their neurons in vitro. It was found that neurons and neural tissue explants from the starfish, Asterias rubens, and the brittlestar, Ophiura ophiura, and explants from the brain of the ascidian, Ciona intestinalis, could be cultured for up to 6 weeks in a modified L15-based medium. Some cells extended axonal projections and produced growth cones under certain conditions. Attempts were made to stimulate neuron survival and outgrowth of echinoderm cultures with conditioned media containing growth factors or tissue extracts and with various substrates including extracellular matrix extracts from native tissue. Ascidian brain explants from both normal and regenerating animals were cultured in the standard conditions established for echinoderm tissue, with outgrowth being observed in 25% of explants. In these cultures labelling with bromodeoxyuridine suggested that regeneration continues in vitro, although results using substance P immunocytochemistry indicate neuronal differentiation may be impeded. These preliminary studies suggest it is possible to maintain adult echinoderm and ascidian neurons in vitro.

Animals↗
PubMed2004

Echinoderm eggs and embryos: procurement and culture.

The protocols outlined here hopefully will provide researchers with healthy, beautiful echinoderm oocytes, eggs, and embryos for experimental use. The large size of echinoderm oocytes and eggs, the ease with which they can be manipulated, and (in many species) their optical clarity, make them an ideal model system for studying not only the events specific to oocyte maturation and fertilization, but also for investigating more general questions regarding cell cycle regulation in an in vivo system. The quick rate at which development proceeds after fertilization to produce transparent embryos and larva makes the echinoderm an advantageous organism for studying deuterostome embryogenesis. Continued use of the echinoderms as model systems will undoubtedly uncover exciting answers to questions regarding fertilization, cell cycle regulation, morphogenesis, and how developmental events are controlled.

Animals↗
PubMed1997

Radical alterations in the roles of homeobox genes during echinoderm evolution.

Echinoderms possess one of the most highly derived body architectures of all metazoan phyla, with radial symmetry, a calcitic endoskeleton, and a water vascular system. How these dramatic morphological changes evolved has been the subject of extensive speculation and debate, but remains unresolved. Because echinoderms are closely related to chordates and postdate the protostome/deuterostome divergence, they must have evolved from bilaterally symmetrical ancestors. Here we report the expression domains in echinoderms of three important developmental regulatory genes (distal-less, engrailed and orthodenticle), all of which encode transcription factors that contain a homeodomain. Our findings show that the reorganization of body architecture involved extensive changes in the deployment and roles of homeobox genes. These changes include modifications in the symmetry of expression domains and the evolution of several new developmental roles, as well as the loss of roles conserved between arthropods and chordates. Some of these modifications seem to have evolved very early in the history of echinoderms, whereas others probably evolved during the subsequent diversification of adult and larval morphology. These results demonstrate the evolutionary lability of regulatory genes that are widely viewed as conservative.

Animals↗
PubMed2003

Reproduction: widespread cloning in echinoderm larvae.

Asexual reproduction by free-living invertebrate larvae is a rare and enigmatic phenomenon and, although it is known to occur in sea stars and brittle stars, it has not been detected in other echinoderms despite more than a century of intensive study. Here we describe spontaneous larval cloning in three species from two more echinoderm classes: a sea cucumber (Holothuroidea), a sand dollar and a sea urchin (Echinoidea). Larval cloning may therefore be an ancient ability of echinoderms and possibly of deutero-stomes - the group that includes echinoderms, acorn worms, sea squirts and vertebrates.

Animals↗
PubMed2003

Larval stages of a living sea lily (stalked crinoid echinoderm).

The embryos and larvae of stalked crinoids, which are considered the most basal group of extant echinoderms, have not previously been described. In contrast, much is known about the development of the more accessible stalkless crinoids (feather stars), which are phylogenetically derived from stalked forms. Here we describe the development of a sea lily from fertilization to larval settlement. There are two successive larval stages: the first is a non-feeding auricularia stage with partly longitudinal ciliary bands (similar to the auricularia and bipinnaria larvae of holothurian and asteroid echinoderms, respectively); the second is a doliolaria larva with circumferential ciliary bands (similar to the earliest larval stage of stalkless crinoids). We suggest that a dipleurula-type larva is primitive for echinoderms and is the starting point for the evolution of additional larval forms within the phylum. From a wider evolutionary viewpoint, the demonstration that the most basal kind of echinoderm larva is a dipleurula is consistent with Garstang's auricularia theory for the phylogenetic origin of the chordate neural tube.

Animals↗
PubMed1989

Phosphagen kinase evolution. Expression in echinoderms.

Arginine kinase and creatine kinase that catalyze the transfer of a phosphate group between ATP and arginine and creatine, respectively, play an important role in cellular energetics. In contrast to most animals which exhibit a single phosphagen kinase activity (creatine kinase in chordates and arginine kinase in protostomians), echinoderms exhibit both arginine kinase and creatine kinase activities, sometimes in the same tissue. In contrast to chordates in which creatine kinases are dimers (consisting of two subunits of 40 kDa) and protostomians in which arginine kinases are usually monomers (40 kDa), echinoids contain specific phosphagen kinases: a dimeric arginine kinase (consisting of two subunits of 42 kDa) in eggs and a monomeric creatine kinase (145 kDa) in sperm. We have examined echinoderms from the five existing classes (echinoids, asteroids, ophiuroids, holothurians and crinoids) for the expression of these specific phosphagen kinases in different tissues. Gel filtration was used to determine the molecular masses of the native enzymes. Antibodies specific for arginine kinase or for creatine kinase were used to characterize the subunit composition of arginine kinase and creatine kinase after SDS/PAGE and transfer. In all echinoderms analyzed, arginine kinase always occurred as an enzyme of about 81 kDa consisting of two subunits of 42 kDa and creatine kinase as a monomeric enzyme of 140-155 kDa. The occurrence in echinoderms of both phosphagen kinases with distinct specificities and specific molecular structures is discussed from both a developmental and evolutionary point of view.

Animals↗
PubMedDate not supplied

Phylogenetic position of Licnophora, Lechriopyla, and Schizocaryum, three unusual ciliates (phylum Ciliophora) endosymbiotic in echinoderms (phylum Echinodermata).

Various echinoderms are colonized by species from several classes of the Phylum Ciliophora, indicating that the echinoderm "habitat" has been invaded independently on numerous occasions throughout evolutionary history. Two "echinoderm" ciliates whose phylogenetic positions have been problematic are Licnophora macfarlandi Stevens, 1901 and Schizocaryum dogieli Poljansky and Golikova, 1957. Licnophora macfarlandi is an endosymbiont of the respiratory trees of holothuroids, and S. dogieli is found in the esophagus of echinoids. A third species, Lechriopyla mystax Lynch, 1930, is a plagiopylid ciliate found in the intestine of echinoids. Host echinoderms were collected near the Friday Harbor Laboratories, San Juan Island, WA. Specimens of S. dogieli and L. mystax were obtained from the esophagus and intestine, respectively, of the sea urchin Strongylocentrotus pallidus. Specimens of L. macfarlandi were collected from the fluid obtained from the respiratory trees of Parastichopus californicus. Using small subunit ribosomal RNA (SSrRNA) sequences of these three ciliates and a global alignment of SSrRNA sequences of other ciliates, we established the following. 1) Licnophora is a spirotrich ciliate, clearly related to the hypotrichs and stichotrichs; this is corroborated by its possession of macronuclear replication bands. 2) Lechriopyla is the sister genus to Plagiopyla and is a member of the Class Plagiopylea, which was predicted based on its cytology. 3) Schizocaryum clusters in the Class Oligohymenophorea and is most closely related to the scuticociliates; there are currently no morphological features known to relate Schizocaryum to the scuticociliates.

Animals↗
PubMed2001

The enteric nervous system of echinoderms: unexpected complexity revealed by neurochemical analysis.

Echinoderms are one of the most important groups of metazoans from the point of view of evolution, ecology and abundance. Nevertheless, their nervous system has been little studied. Particularly unexplored have been the components of the nervous system that lie outside the ectoneural and hyponeural divisions of the main nerve ring and radial nerve cords. We have gathered information on the nervous components of the digestive tract of echinoderms and demonstrate an unexpected level of complexity in terms of neurons, nerve plexi, their location and neurochemistry. The nervous elements within the digestive system consist of a distinct component of the echinoderm nervous system, termed the enteric nervous system. However, the association between the enteric nervous system and the ectoneural and hyponeural components of the nervous system is not well established. Our findings also emphasize the importance of the large lacunae in the neurobiology of echinoderms, a feature that should be addressed in future studies.

Animals↗
PubMedDate not supplied

[Comparative immunological analysis of echinoderm cellular and humoral defense factors].

Coelomocyte are found in the fluid filling coelomic cavity of echinoderms and depending on species can be a mixture of several morphologically different types. There are among them: granular and agranular amoebocytes, morula cells, vibratile and lymphocyte-like cells. All these cells take part in cellular response to immune challenges through phagocytosis, clotting, encapsulation of foreign particles, cytotoxicity, and the production of antimicrobial agents, such as reactive oxygen and nitric oxide. The data are given on a variety of humoral factors found in the coelomic fluid, including different types of lectines, agglutinins, hemolysins, acute phase proteins and antimicrobial factors. The discussion on cooperation between cellular and humoral arms of defense reactions during inflammation reveals the crucial role of coelomocytes in immune response. It is suggested that the sea urchin complement system (that is homologous to the alternative pathway in vertebrates) is appeared initially in echinoderms as a protein cascade that points to opsonization of foreign cells and particles, augmenting their phagocytosis and subsequent destruction by coelomocytes. So the identification of a simple complement system as a part of the echinoderm immune response shows that these animals as well as all invertebrate deuterostomes share innate immune system homologies with vertebrates. Studying the simpler immune response demonstrated by echinoderms is important for understanding the ancestral deuterostome defense system and reconstructing the evolution of immune system in higher vertebrates.

Animals↗
PubMed2001

Autotomy as a prelude to regeneration in echinoderms.

'Autotomy' refers to the adaptive detachment of animal body parts where this serves a defensive function, is achieved by an intrinsic mechanism, and is nervously mediated. With regard to each echinoderm class, this article itemises those structures that are autotomous, evaluates the extent to which autotomy precedes regeneration in natural populations, reviews current knowledge of the morphology of autotomy planes and mechanisms that effect fracture at autotomy, and comments on autotomy-related issues arising from studies of the cellular events of regeneration. Each autotomy plane can be regarded as an assemblage of breakage zones traversing the individual anatomical components of the autotomous structure. In any one autotomy plane some breakage zones are permanent sites of weakness that are fractured by external forces and some are potential sites of weakness that undergo a loss of tensile strength only at the time of autotomy. The latter occur predominantly in mutable collagenous structures, although there are a few examples of muscles that undergo an endogenous rupturing process. Available evidence indicates that autotomy is by far the commonest proximate cause of structural loss in echinoderms. Most echinoderm regeneration is therefore necessitated by autotomy and proceeds from the retained side of a fractured autotomy plane. Due to a lack of relevant research there is as yet little evidence for or against the presence of specific regeneration-promoting adaptations at autotomy planes, although it is argued that an autotomy plane designed primarily to effect rapid detachment would by itself increase regenerative efficiency.

Animals↗
PubMed2005

Are echinoderms of interest to biotechnology?

The huge potential of echinoderms as a so far fairly untapped source of bioactive molecules is described. Examples are presented that show the usefulness of echinoderm-derived molecules for therapeutic application in selected fields of cancer research, in the control of bacterial growth as substances with new antibiotic properties, and finally in the context of technical applications such as antifouling substances. The molecules described here are but the mere beginning of a commercial exploitation of echinoderms and may incite a deeper involvement of biotechnology-oriented research in this material.

Animals↗