Purple Sea Urchin Strongylocentrotus Purpuratus Research Articles

The effects of hydrodynamic shear stress on fertilization and early development of the purple sea urchin Strongylocentrotus purpuratus.

Life in the highly turbulent surf zone poses a severe challenge to reproduction in free-spawning animals. Not only can breaking waves quickly dilute the gametes shed by spawning organisms, but turbulence-induced shear stresses may limit fertilization and interfere with normal development. A Couette cell was used to re-create some of the effects of turbulent water motion to study effects of environmentally relevant shear stresses on fertilization in the purple sea urchin (Strongylocentrotus purpuratus). Although low shear stresses improved fertilization success (presumably by increasing mixing), exposure to high shear stresses (of the magnitude found in the surf zone) substantially decreased fertilization success, probably by interfering with contact between egg and sperm. Furthermore, eggs fertilized at high shear stresses often showed abnormal development and low survival of eggs through the blastula stage.

The sea urchin profilin gene is specifically expressed in mesenchyme cells during gastrulation

Eggs and embryos of the purple sea urchin (Strongylocentrotus purpuratus) contain profilin that is partly supplied from maternal sources and partly produced by the gastrula. The maternal profilin protein content is about 13 microM and it persists in the embryo at least through gastrulation. Transcript quantitation from probe excess titrations show that very few profilin gene transcripts are present in the embryo during cleavage, but that they increase at the onset of gastrulation. By in situ hybridization, the newly synthesized profilin transcripts are localized in mesenchyme cells. Profilin gene expression increases when mesenchyme cells initiate migration and filopodial extension and retraction. We show that there are three isoforms of maternal profilin protein produced from the single copy gene during oogenesis. However, the blastula stage embryo only produces the major isoform, whereas the acidic isoform is produced in the early stages of gastrulation and the basic isoform appears by the end of gastrulation. Based on transcript prevalence and protein production rates, our calculations indicate that the amount of new protein produced in the mesenchyme cells in 12 hr is at maximum < 2% of that supplied from maternal sources. Because of the large amount of maternally supplied profilin present in the egg and embryo, we suggest that it may be used in the cytokinetic processes of cleavage. Alternatively, because of the small amount of embryonically produced profilin, we suggest that it may function in the cytoskeletal shape changes required for filopodial extension and motility in the mesenchyme cells during gastrulation.

Evaluation of silkworm pupae meal as a dietary protein source for Clarias batrachus fingerlings

In the field of biomineralization, the past decade has been marked by the increasing use of high throughput techniques, i.e. proteomics, for identifying in one shot the protein content of complex macromolecular mixtures extracted from mineralized tissues. Although crowned with success, this approach has been restricted so far to a limited set of key-organisms, such as the purple sea urchin Strongylocentrotus purpuratus, the pearl oyster or the abalone, leaving in the shadow non-model organisms. As a consequence, it is still unknown to what extent the calcifying repertoire varies, from group to group, at high (phylum, class), median (order, family) or low (genus, species) taxonomic rank.The present paper shows the first biochemical and proteomic characterization of the test matrix of the Mediterranean black sea urchin Arbacia lixula (Arbacioida). Our work suggests that the skeletal repertoire of A. lixula exhibits some similarities but also several differences with that of the few sea urchin species (S. purpuratus, Paracentrotus lividus), for which molecular data are already available. The differences may be attributable to the taxonomic position of the species considered: A. lixula belongs to an order – Arbacioida – that diverged more than one hundred million years ago from the Camarodonta, which includes the two species S. purpuratus and P. lividus. For the echinoid class, we suggest that large-scale proteomic screening should be performed in order to understand which molecular functions related to calcification are conserved and which ones have been co-opted for biomineralization in particular lineages.

Effects of an oil production effluent on gametogenesis and gamete performance in the purple sea urchin (Strongylocentrotus purpuratus stimpson)

AbstractAdult organisms subjected to chronic discharges from a point source of pollution may exhibit several sublethal responses. One such response is the impairment of gamete production. This may be expressed in the amount and/or quality of gametes produced by adults. In this study the effects of chronic exposure to produced water (an oil production effluent) on the gametogenesis and gamete performance of the purple sea urchin (Strongylocentrotus purpuratus Stimpson) were examined using an in situ caging experiment Adult purple sea urchins were kept in benthic cages arrayed down‐field from a discharging dif‐fuser at 13 sites, with distances ranging from 5 to 1,000 m. Cage exposures were maintained in the field for eight weeks, and each cage held 25 animals Gametogenesis was examined for each sex by comparing a size‐independent measure of relative gonad mass as determined by analysis of covariance. Results showed that there was a significant negative relationship between these estimates of relative gonad mass and distance from the outfall for both sexes, indicating that sea urchins living closer to the outfall produced significantly larger gonads. Gamete performance was measured through a fertilization kinetics bioassay that held the concentration of eggs constant and varied the amount of sperm added The proportion of eggs fertilized under each sperm concentration was determined and the response fit to a model of fertilization kinetics This experiment showed significant differences in the fertilizabihty of eggs between cages, and egg fertilizabihty showed a positive relationship with distance away from the outfall These findings indicate that although adult sea urchins exposed to a produced water outfall exhibit larger gonads, they suffer a marked decrease in gamete performance

Toxicokinetics and biotransformation of pentachlorophenol in the sea urchin (Strongylocentrotus purpuratus).

1. The toxicokinetics and biotransformation of pentachlorophenol (PCP) were determined in the purple sea urchin (Strongylocentrotus purpuratus). 2. In a static chamber, urchins (n = 9) were individually exposed to 50 micrograms/l of [U-14C]PCP for 24 h to determine bioconcentration and the absorption rate constant (Ka), elimination rate constant (Ke), and elimination half-life (t1/2). Determination was by direct quantitation of radioactivity in the exposure water. 3. After exposure, urchins were placed in a flow-through chamber for 24 h to allow depuration of retained residues, which were identified by hplc and quantified by lsc. The Ka and Ke, calculated using a simplified model, were 0.12 +/- 0.06 h and 0.43 +/- 0.22 h, respectively, whilst the 24-h total concentration factor was 316.3 +/- 209.7, and the t1/2 was 1.6 +/- 0.8 h. 4. Whereas urchins depurated 40.6% of retained residues, only a small amount of PCP was excreted unchanged (17.0%), as the more polar conjugates pentachlorophenyl-beta-D-glucoside (72.4%) and pentachlorophenylsulphate (10.6%) were also formed.

Genomic Structure, Chromosomal Location, and Evolution of the Mouse Hox 8 Gene

We isolated genomic clones containing the mouse Hox 8 gene, a member of the msh gene family. We show that Hox 8 comprises two exons of approximately 600 and 691 bp separated by a 3.5-kb intron, and that it cosegregates with previously mapped markers in the distal region of mouse chromosome 13. In midgestation embryos, the Hox 8 gene produces transcripts of 1.4 and 2.2 kb. Both transcripts are present in facial tissues of the newborn mouse, though the ratio of the 2.2-kb transcript to the 1.4-kb transcript is reduced relative to the ratio observed for midgestation embryos. An alignment of the homeobox sequences of previously characterized members of the msh family revealed three subclasses: Hox 7-like genes, Hox 8 -like genes, and msh-like genes. Both the Hox 7-like genes and Hox 8-like genes are present throughout the vertebrates. Representatives of the third subclass, the msh-like genes, are found in a protostome (Drosophila) and a deuterostome (Ciona) and are thus likely to be phylogenetically widespread. To investigate the distribution of Hox 8 -like genes outside the chordates, we used the polymerase chain reaction and degenerate Hox 8 primers to screen genomic DNA of the purple sea urchin (Strongylocentrotus purpuratus, Phylum Echinodermata). We isolated a gene with greater sequence similarity to mouse Hox 8 than to members of the Hox 7 or msh subfamilies, demonstrating that the Hox 8 subfamily has been in existence at least since the echinoderms diverged from the lineage that gave rise to the chordates. The remarkable sequence conservation of the Hox 8-like homeobox suggests that its target sequence, and, perhaps, other aspects of its function, has remained unchanged for more than 500 million years.

Response of embryos of the sea urchin Strongylocentrotus purpuratus to aqueous petroleum waste includes the expression of a high molecular weight glycoprotein

The present study investigated the sublethal effects of the largest aqueous waste associated with offshore oil development, produced water (PW), on sea urchin embryo development. PW inhibited normal gastrulation in purple sea urchin (Strongylocentrotus purpuratus) embryos exposed at the hatching stage. The exposed embryos did not form complete archenterons, and secondary mesenchyme cells exhibited an unusual behavior with respect to the wall of the blastocoelic cavity. In addition, an abundance of extracellular matrix was observed in the blastocoelic cavities in the embryos exposed to higher concentrations of PW. An inhibition of the development of embryos through the pluteus stage was observed as a result of PW exposure. This was manifested by inhibition of normal spicule formation with concomitant abnormal pluteus morphology. To determine if a biochemical stress response occurs as a result of PW exposure, embryos at the early gastrula stage were exposed to PW for 2 h, followed by an additional 1 h in 3H-leucine and PW. These embryos expressed a 253 kDa protein as observed by one-dimensional SDS (sodium dodecyl sulfate) polyacrylamide gel electrophoresis and autoradiography. This protein could occasionally be observed in gels stained for protein, and was glycosylated as demonstrated by staining with periodic acid Schiff (PAS). The 70 to 73 kDa heat-shock proteins previously described in sea urchin embryos (and other organisms) as a result of stress were not synthesized as a result of PW exposure. Heat shock did not induce synthesis of the 253 kDa glycoprotein. Combined PW and heat-shock exposure elicited both the heat-shock response (73 kDa protein) as well as expression of the 253 kDa glycoprotein. These data demonstrate the use of expression of endogenous macromolecular markers to distinguish exposures of embryos to different perturbations. Arsenic (as sodium arsenite), a metal constituent of PW, also induced the 253 kDa glycoprotein in early gastrula-stage embryos. We suggest that this glycoprotein may be a marker for PW (and a metal constituent) exposure in sea urchin embryos, and may be related to morphological abnormalities.

Plastic responses to limited food availability and spine damage in the sea urchin Strongylocentrotus purpuratus (Stimpson)

The purple sea urchin Strongylocentrotus purpuratus (Stimpson) has been shown to exhibit phenotypic variation that is dependent on habitat. The interaction of two common conditions existing in the intertidal zone; viz., food limitation and wave action resulting in spine damage, were explored under laboratory conditions. Changes in overall size, test weight, and jaw length were determined as urchins were subjected to different food levels and spine damage. Results indicate that food availability influences overall growth to a greater degree than does spine damage. An increase in the length of the jaws begins almost immediately following a reduction in the amount of food. Animals that were subjected to spine damage, in addition to repairing spines, appeared to allocate a greater amount of material to the lanterns and tests, which suggests that spine repair may stimulate overall calcification. Reinforcement of the test clearly has survival value for sea urchins of exposed rocky shores.

Allocation of45calcium to body components of starved and fed purple sea urchins (Strongylocentrotus purpuratus)

Several lines of evidence in the literature indicate that environmental stress such as starvation may initiate reallocation of sea urchin endoskeletal tissue. For example, Aristotle's lantern enlarges under conditions of starvation, and sea urchins tagged with tetracycline and then fed develop a distinct growth line, while starved individuals develop a diffuse pattern. We designed anin vivo system to examine stress-related changes in calcification in the purple sea urchinStrongylocentrotus purpuratus. SmallS. purpuratus (ca. 2 cm test diam) were collected from the Mission Bay jetty or Imperial Beach (San Diego, California, USA) in 1987.45Ca was incorporated from seawater into all body fractions including the organic tissue/coelomic fluid. In an initial experiment, sea urchins were fed or starved for 4 wk and then post-incubated in isotope. Overall, starved individuals deposited new calcite more slowly than did fed individuals; however, allocation was very different and calcification of teeth of starved sea urchins was nearly as great as in fed individuals. In a second experiment,S. purpuratus were first pre-labeled with isotope and then treated by feeding or starving. More of the labeled calcium was mobilized from the soft tissues and coelomic fluid into calcite in fed than in starved individuals. Growth of the teeth in starved sea urchins was significantly greater than in those fed. We conclude that starvation changes the metabolism of calcium in order to preferentially build teeth. However, we also found no evidence that calcium was resorbed from “old” skeletal calcite in order to build “new” skeleton.

Newly settled sea urchins in a kelp bed and urchin barren ground, a comparison of growth and mortality

Growth of newly settled purple sea urchins Strongylocentrotus purpuratus was studied using laboratory rearing of individuals at natural densities, size-frequency analysis of a recently settled cohort collected in field samples, and mark-recapture techniques with individuals injected with tetracycline. In the laboratory, sea urchins were reared on crustose coralline algae as characteristic of a sea-urchin barren ground (barrens), and on foliose red algal turf as characteristic of a kelp bed. Growth in a barrens was compared with growth in a kelp-bed habitat using all 3 methods. Field work was done at 2 subtidal sites near Santa Barbara, California, USA, from 1985 through 1987. S. purpuratus in the laboratory grew at similar rates for the first 50 d after settlement regardless of substrata (0.29 to 0.45 mm mo-l), and in the field grew slightly, but significantly, faster in the barrens (0.42 mm mo-') than in the kelp-bed (0.31 mm mo-l). At roughly 50 d of age and 0 8 to 1.2 mm test diameter, sea urchins switched from feeding by surface scraping to grazing on fleshy algae. Thereafter, growth was signlflcantly faster in the presence of macroalgae (0.56 to 1.67 mm mo-l), than in habitats or treatments without fleshy algae (0.12 to 0.27 mm mo-'). Based on these results, S purpuratus diameter at 1 yr old was estimated to be 3.6 mm in barrens and 17 mm in kelp-bed habitats. Newly settled sea urchins suffered higher mortality in the kelp bed than in the barrens, but individuals at slightly greater ages showed no detectable difference in mortality between the 2 habitats. The attainment of a threshold size for switching diets and increasing growth rate (if algae is available) may be a critical event in a sea urchin's life-history.

Latitudinal variation in size structure of the west coast purple sea urchin: A correlation with headlands1

Size structure of the purple sea urchin Strongylocentrotus purpuratus was sampled from central California to central Oregon (36°– 45°N). Size frequency and inferred recruitment events are correlated with major topographic features. Capes and headlands—predictable sites of upwelling and locations of cold water plumes— show size frequencies indicative of low recruitment rates. Sites without predictable upwelling or regions that are between headlands have size frequencies that indicate substantial annual recruitment.

Life history traits and resource allocation in the purple sea urchin Strongylocentrotus purpuratus (Stimpson)

Variation in recruitment and longevity of the purple sea urchin Strongylocentrotus purpuratus (Stimpson) along its latitudinal distribution suggests clinal differences in the life history traits of this species. Two complimentary approaches were employed to assess degree and nature of the intraspecific variation in life history traits. Growth, mortality and recruitment data were gathered in the field and in the laboratory sea urchins were held under the same conditions to determine the extent of plasticity in resource allocation. Both laboratory and field measurements indicate the observed demographic patterns are best attributed to phenotypic responses to varying environmental conditions rather than genetically determined intraspecific differences in life history traits.

Utilization of purple and red sea urchins ( Strongylocentrotus purpuratus Stimpson and S. franciscanus Agassiz) as food by the white sea urchin ( Lytechinus anamesus Clark) in the field and laboratory

White sea urchins ( Lytechinus anamesus Clark) attacked purple ( Strongylocentrotus purpuratus Stimpson) and red ( S. franciscanus Agassiz) sea urchins at Anacapa Island, California. Densities of white urchins were highest in the deep algal crust-dominated community where up to 6% of purple and 25% of red urchins were being attacked by white urchins. Up to 9% of Lytechinus anamesus in an area were actively eating stronglylocentrotids and usually, more than one white urchin was involved in the attack. In areas with low densities of white urchins, no strongylocentrotids were being attacked. After 36 h in the laboratory, there was no difference in the number of white urchins attacking injured or healthy purple urchins in each of the three experimental densities of white urchins. However, both injured and healthy urchins were attacked by more white urchins in high density. When given a choice between injured purple urchins or fresh kelp, white urchins overwhelmingly chose kelp. Data suggest that white urchins utilize other urchin species as an alternative source of food when more preferred food is absent, but will switch to preferred food should it become available.

Developmental and cytogenetic abnormalities induced in the purple sea urchin by environmental levels of benzo(a)pyrene.

The teratogenic effects of environmental levels of the mutagen, benzo(a)pyrene (BaP), were investigated using the purple sea urchin (Strongylocentrotus purpuratus) and were related to embryonic cytotoxicity and genotoxicity as evidenced by the presence of aberrant chromosome arrangements during mitosis. Developmental abnormalities were observed in gastrulae treated with initial BaP concentrations of 1 to 50 ng/ml relative to solvent (ethanol)-treated control embryos. However, genotoxic effects were significant at the lowest BaP dose tested, 0.5 ng/ml. When compared to seawater and ethanol control embryos, fewer mitotic figures and increased frequencies of abnormal mitoses were present in BaP-treated gastrulae. Micronucleus formation, a widely used test of genotoxicity in mammals, was observed in embryos exposed to 1 to 50 ng/ml BaP. Grossly abnormal test embryos had high incidences of mitotic aberrations and were composed of large numbers of pycnotic, karyolytic, and multinucleated cells. The results from this cytogenetic analysis demonstrate that mitotic inhibition and aberrations are more sensitive indicators of BaP-induced damage than are developmental effects and suggest that cytogenetic analysis be included in the standard 48-hr sea urchin bioassay procedure when testing contaminants suspected of being mutagens. Cytologic-cytogenetic analysis is particularly suited for use with invertebrates and appears to be as sensitive as more laborious and expensive routine cytogenetic methods which involve karyotyping such as the sister chromatid exchange test.

Potassium is not compartmentalized within the unfertilized sea urchin egg

Virtually all of the potassium in the unfertilized eggs of the purple sea urchin Strongylocentrotus purpuratus is in a single compartment and is exchangeable with extracellular potassium. This conclusion is based on an analysis of 42K uptake and efflux experiments and is in conflict with some claims of other investigators.

Growth Rates of the Sea Urchin Strongylocentrotus Purpuratus Related to Food Availability and Spine Abrasion

A population of the purple sea urchin Strongylocentrotus purpuratus Stimpson was studied at Sunset Bay, Oregon. Three sub—populations had different size—frequency distributions. Such differences in size resulted from differences in growth rate and ultimate size. Two environmental components were examined as possibly causing the different rates of growth: a component of "weather" which broke spines, and food availability and consumption. These two components are important in determining growth rate and ultimate size of these animals.

Digestion of brown algae and the distribution of nutrients in the purple sea urchin Strongylocentrotus purpuratus

1. 1. The purple sea urchin Strongylocentrotus purpuratus digests the brown algae Macrocytis pyrifera and Egregia Laevigata with high efficiency, averaging 80 per cent digested for the former and 62 per cent for the latter. The brown algae Petalonia fascia and Halidrys dioica are not the usual diet of this animal and are digested with lower efficiencies, 50 and 44 percent respectively. 2. 2. When digestive efficiencies during continual feeding are compared with those after a single feeding, there appears to be little difference between them. 3. 3. Macrocystis labeled with C 14 was fed to S. purpuratus and the time of appearance and distribution of C 14 were subsequently examined. Within a few hours the plasma of the perivisceral fluid becomes radioactive with a soluble product of digestion which proved to be mannitol, a sugar alcohol which comprises 30 per cent of the alga's dry weight (ash-free). Peaks of radioactivity in the plasma appear as often as radioactive meals are offered to the urchin. Over longer periods the C 14 is concentrated chiefly in the first and second circuits of the intestine, but incorporation of C 14 into the gonads occurs much more slowly. 4. 4. The red and white coelomocytes of the perivisceral fluid become radioactive later than the plasma. A high specific activity is reached and maintained in the red coelomocytes hours after the radioactive meal. The number of red coelomocytes in the perivisceral fluid fluctuates, suggesting that these cells may be migrating into and out of the perivisceral fluid. 5. 5. A chemical test for glycogen shows that the red coelomocytes are rich in this polysaccharide in well-fed urchins. 6. 6. Injection of radioactive red coelomocytes into the perivisceral fluid of a non-radioactive urchin results in a distribution of the radioactivity into the tissues of the chemical. 7. 7. Evidence is presented of hitherto unknown connections of the hemal system between the gonads and intestines. These connections are filled with re coelomocytes. 8. 8. It is suggested that the hemal system may represent a true ciculatory system in the sea urchin S. purpuratus and that the red coelomocytes distribute products of digestion throughout the body by this system.