Luidia Clathrata Research Articles

The dopamine receptor antagonist haloperidol disrupts behavioral responses of sea urchins and sea stars.

Despite lacking a brain and having an apparent symmetrically pentaradial nervous system, echinoderms are capable of complex, coordinated directional behavioral responses to different sensory stimuli. However, very little is known about the molecular and cellular mechanisms underlying these behaviors. In many animals, dopaminergic systems play key roles in motivating and coordinating behavior, and although the dopamine receptor antagonist haloperidol has been shown to inhibit the righting response of the sea urchin Strongylocentrotus purpuratus, it is not known whether this is specific to this behavior, in this species, or whether dopaminergic systems are needed in general for echinoderm behaviors. We found that haloperidol inhibited multiple different behavioral responses in three different echinoderm species. Haloperidol inhibited the righting response of the sea urchin Lytechinus variegatus and of the sea star Luidia clathrata. It additionally inhibited the lantern reflex of S. purpuratus, the shell covering response of L. variegatus and the immersion response of L. variegatus, but not S. purpuratus or L. clathrata. Our results suggest that dopamine is needed for the neural processing and coordination of multiple different behavioral responses in a variety of different echinoderm species.

Genetic Evidence Supports Species Delimitation of Luidia in the Northern Gulf of Mexico.

AbstractAccurate species delimitation is crucial to understanding biodiversity. In the northern Gulf of Mexico, recent genetic evidence has suggested that the tricolor Luidia lawrencei is not a species distinct from the gray Luidia clathrata. We collected Luidia specimens from Apalachee Bay, Florida, and morphologically identified 11 as L. clathrata and 16 as L. lawrencei. We sequenced 1074 bp of the cytochrome c oxidase subunit I (COI) and found ~14% divergence between L. clathrata and L. lawrencei, suggesting two distinct species (within-species divergence was <1%). Two specimens were phenotypically L. lawrencei (i.e., tricolor morph) but mitochondrially were L. clathrata. Our findings lend support to maintaining L. clathrata and L. lawrencei as distinct species. However, the species boundary between these two taxa may be porous, and ongoing hybridization may occur when the two species are found in sympatry. Future work with nuclear markers is warranted to determine the frequency of hybridization and the extent of introgression. Clarifying the genetic relationship between these species will provide a baseline for assessing ongoing changes in connectivity of these two highly abundant sea stars in the rapidly warming northern Gulf of Mexico.

Bycatch of Asteroidea from shrimp trawl fishery in the southwestern Atlantic Ocean – Brazil

Shrimp trawling is considered a significant negative impact on the marine ecosystem, especially on the benthic community. Sea stars (Echinodermata: Asteroidea) are one of the most affected groups by unintentional catches. This study was performed at the Santana Archipelago, a Marine Protected Area in the northern region of Rio de Janeiro State, between 2008-2009. Sea stars accidentally caught by trawling were collected during open and closed season of the shrimp fisheries (Xiphopenaeus kroyeri) at depths of 5-60 m. A generalized linear zero-inflated model was applied to test for differences in capture between fishing seasons and depths. A total of 158 sea star specimens were captured. These specimens were identified as Asterina stellifera, Astropecten acutiradiatus, Astropecten brasiliensis, Astropecten cingulatus, Luidia alternata alternata, Luidia clathrata, Luidia ludwigi scotti, Luidia senegalensis. The sea stars A. brasiliensis and L. senegalensis are currently considered as vulnerable species in the Brazilian official list of threatened species. The higher capture of sea stars was shown in deepest areas, and there was no significant difference in the number of specimens between seasons. This is the first study about asteroids accidentally captured by shrimp trawling.

Reversal of priority for the species name Asterias clathrata Say, 1825 over its senior homonym Asterias clathrata Pennant, 1777: maintenance of prevailing usage

The widely known and ecologically important sea star species, Luidia clathrata, was originally named Asterias clathrata by Say, 1825. This name is a junior homonym of Asterias clathrataPennant, 1777. The senior homonym has not been used as a valid name since 1899, fulfilling Article 23.9.1 of the Code, which reverses the priority of Asterias clathrataSay, 1825 over its senior homonym Asterias clathrataPennant, 1777. Here, in accordance with Article 23.9.2, we declare Asterias clathrataSay, 1825 a nomen protectum and Asterias clathrataPennant, 1777 a nomen oblitum.

Effects of salinity and feeding on arm regeneration in the starfish Luidia clathrata (Say, 1825) (Echinodermata: Asteroidea)

ABSTRACTThe aim of this study was to determine: (1) salinity that maximizes arm regeneration in the starfish Luidia clathrata; and (2) if low food consumption or low salinity is the cause of the reduced rate of arm regeneration seen at low salinities.. An estimated salinity of 33 g kg−1 produced maximum regeneration of two arms in L. clathrata. This salinity is typically greater than that found in bays that are the usual habitat for the species. Equivalent food consumption by L. clathrata in salinities of 20 g kg−1 and 30 g kg−1 resulted in greater regeneration in salinity of 30 g kg−1, suggesting lower food consumption at low salinities is not the primary reason for lower regeneration. Higher food consumption compared to lower food consumption, both tested in salinity of 30 g kg−1, did not increase regeneration, but resulted in more storage of energy in the pyloric caeca.

Telomere elongation and telomerase expression in regenerating arms of the starfish Luidia clathrata (Asteroidea: Echinodermata)

Regeneration in echinoderms has been extensively characterized physiologically, but fewer studies have addressed the genetic mechanisms underlying the process. Telomeres, genetic sequences on the ends of chromosomes that shorten with cell division, are associated with cell senescence, and thus genetic age after cell growth. Relative telomere lengths in the starfish Luidia clathrata were measured in arms of juveniles, adults prior to injury, and adults after injury during initial regeneration. Additionally, relative telomerase expression was measured in arms of adults prior to injury, at wound closure, and during initial regeneration. Telomeres were longer in juveniles than uninjured adults, indicating genetic aging. Telomeres elongated in adults after injury. Telomerase was detected before and after injury. The combination of genetic aging and telomerase expression both before and after injury suggests possible post-transcriptional regulation of telomerase. Additionally, as previous studies did not detect elongated telomeres in regenerated arms, it is possible that telomere elongation occurs early in the regenerative process as a mechanism to permit cellular division for growth without aging the final regenerated arm.

Salinity effects on arm regeneration in Luidia clathrata (Echinodermata: Asteroidea)

The effect of salinity (20, 25, and 30 psu) on regeneration of two arms of adult starfish Luidia clathrata (n = 8 per salinity treatment group collected from Pensacola Bay, Florida, USA 30° 20′ N, 87° 13′ W) was examined in a laboratory experiment (November 2009 to March 2010) to test the hypothesis that L. clathrata is adapted to euryhaline conditions found in bays with regards to arm regeneration. Regenerating arm condition (lengths and weights) relative to treatment was 20-psu treatment < 25-psu treatment < 30-psu treatment, and non-regenerating arm condition was 20-psu treatment < 25-psu treatment = 30-psu treatment. Luidia clathrata is not adapted to lower salinity conditions found in bays with regard to arm regeneration, despite the common occurrence of the species in bays. Lower salinity in bays should reduce the ability of L. clathrata to recover from damage sustained during, or just prior to, low-salinity periods.

Regenerative capacity and biochemical composition of the sea star Luidia clathrata (Say) (Echinodermata: Asteroidea) under conditions of near-future ocean acidification

The present study examines sublethal effects of near-future (year 2100) ocean acidification (OA) on regenerative capacity, biochemical composition, and behavior of the sea star Luidia clathrata, a predominant predator in sub-tropical soft-bottom habitats. Two groups of sea stars, each with two arms excised, were maintained on a formulated diet in seawater bubbled with air alone (pH 8.2, approximating a pCO2 of 380μatm) or with a controlled mixture of air/C02 (pH 7.8, approximating a pCO2 of 780μatm). Arm length, total body wet weight, and righting responses were measured weekly. After 97days, a period of time sufficient for 80% arm regeneration, pyloric caecal indices, and protein, carbohydrate, lipid, and ash levels were determined for body wall and pyloric caecal tissues of intact and regenerating arms of individuals held in both seawater pH treatments. The present study indicates that predicted near-term levels of ocean acidification (seawater pH 7.8) do not significantly impact whole animal growth, arm regeneration rates, biochemical composition, or righting behavior in this common soft bottom sea star.

Seasonal changes in the density and species composition of the epifaunal echinoderms recorded from the southwestern Gulf of Mexico

The distribution and relative abundance of epifaunal echinoderms in the Southwestern region of the Gulf of Mexico based on 181 collections by the use of an Otter Trawl during different years are described. A total of 59 species were recorded, and represent the following five classes; Asteroidea 25 species, Ophiuroidea 15 species; Echinoidea 14 species, Crinoidea 4 species, and Holothuroidea 1 species. The most frequently encountered single species was Luidia clathrata found at 68 % of all the stations sampled. Furthermore, Astropecten nitidus Astropecten duplicatus, Mellita quienquiesperforata, Brissopsis atlantica, Brissopsis elongata, Astropecten articulatus, Luidia alternata, Comactinia meridionalis, Astropecten alligator, Astropecten cingulatus, Tethyaster grandis, and Clypeaster ravenelii, were species less abundant and frequent and accounted for 13% of the remaining percentage of the echinoderms collected and identified. The starfish Luidia clathrata was the largest species size collected on the Campeche Bank at 16 m depth. The highest seasonal density of the echinoderms was recorded in Autumn on carbonate substrate, whereas the highest species richness was found in summer. Rev. Biol. Trop. 56 (Suppl. 3): 297-310. Epub 2009 January 05.

Bioassay-guided fractionation of antifouling compounds using computer-assisted motion analysis of brown algal spore swimming

Antifouling extracts from the sea stars Astropecten articulatus and Luidia clathrata and from the brittle star Astrocyclus caecilia were fractionated by solid phase extraction and high performance liquid chromatography. Bioactive fractions were identified with the use of computer-assisted motion analysis-based bioassays utilising previously described Hincksia irregularis spore swimming behaviour parameters. Quantified parameters of spore movement were rate of change of direction (RCD) and speed (SPEE). The methods used initially required only 10 μg equivalent amounts of total crude extract and each resultant resolving step (normalised to 1 mg ml−1 of crude, unfractionated extract) required far less material. Statistical analyses of RCD and ratios of RCD:SPEE values in experiments comparing swimming in the presence of extract fractions to controls revealed that both parameters were useful individually and in combination for efficiently following compound bioactivity throughout the fractionation procedure. This technique was also able to detect synergistic or additive interactions between compounds.

A New Antifouling Bioassay Monitoring Brown Algal Spore Swimming Behaviour in the Presence of Echinoderm Extracts

Epibiosis, the colonization of biogenic surfaces by epibiotic organisms such as bacteria, filamentous algae, and sessile invertebrates, poses a major threat to the fitness and survival of macroorganisms which could potentially be fouled. Fouling of artificial submerged structures can also cause severe economic problems, making the need for refined bioassays to determine the efficacy of potential antifouling compounds even more important. The aim of this study was to use the distinct swimming behaviour of zoospores of the fouling brown alga Hincksia irregularis to develop a new laboratory antifouling bioassay to test the effect of marine natural products. Spores were exposed to different concentrations of aqueous and organic extracts from body walls of sympatric echinoderms (Asteroidea: Luidia clathrata, Astropecten articulatus; Ophiuroidea: Astrocyclus caecilia). Computer-assisted motion analysis was used to distinguish between the straight and fast swimming movements of undisturbed spores (controls) and the helical and erratic swimming patterns of chemically irritated spores, using the quantitative parameters rate of direction change (RCD) and swimming speed (SPD). The ratio RCD/SPD of spore swimming paths at extract treatments compared to controls can be used to quantify the detrimental effect of echinoderm extracts. Echinoderm extracts had significant effects on spore swimming behaviour at concentrations three orders of magnitude lower than that present naturally in the echinoderm body walls (mg extract/dry weight echinoderm body wall). Comparative studies on spore settlement and germination under similar treatment conditions show that changes in spore swimming behaviour reflect decreased fitness and survivourship of algal spores. It is suggested that this bioassay can be used to screen potential antifouling extracts and compounds at very low concentrations, making this assay particularly suitable for detection of concentration dependent effects and for bioassay-guided fractionation of extracts to identify active compounds.

A NOVEL BIOFOULING ASSAY USING COMPUTER‐ASSISTED MOTION ANALYSIS OF HINCKSIA IRREGULARIS SPORE SWIMMING

Computer‐assisted motion analysis of the swimming behavior of spores of the brown alga Hincksia irregularis was used in a novel antifouling bioassay. Newly released spores were exposed to water soluble compounds of organic and aqueous body wall extracts of two sympatric sea stars, Astropecten articulatus and Luidia clathrata. Changes in the swimming behavior of H. irregularis spores were quantified by changes in speed (decrease at extract exposure) and rate of change of direction (increase at extract exposure). Sea star extracts were tested at natural concentrations (mg extract/g wet weight) and at approximate 10‐, 100‐, and 1000‐fold dilution. Significant effects (p ≤ 0.05) were observed at 1000‐fold dilution of the natural concentration in both extracts of A. articulatus, and at 100‐ and 10‐fold dilution of the aqueous and organic extract, respectively, in L. clathrata. Germination of spores after short time exposure (30 min) to sea star body wall extracts indicates that compounds were not toxic but affected spore mobility, a factor that plays an important role during spore settlement. We suggest that this assay is very useful for bioassay‐guided fractionation of extracts because it is very sensitive and requires only small amounts of extracts or isolated compounds.

Rate of regeneration of two arms in the field and its effect on body components in Luidia clathrata (Echinodermata: Asteroidea).

The incidence of arm regeneration, effects of arm regeneration on non-regenerating body components and rate of arm regeneration were examined under field conditions. Approximately 60% of Luidia clathrata found in the upper portion of Tampa Bay, Florida were regenerating one or more arms. Individuals with two arms amputated at the disk edge took 380 days to regenerate completely. Both arms of an individual regenerated at the same rate. Length of regenerating arms initially increased faster than dry mass. No difference was found between non-regenerating and regenerating individuals for the dry mass of the body wall, pyloric caeca, and gonad of a non-regenerating arm. The absolute masses of the gonad and pyloric caeca were low through out the year possibly indicating a low food environment. Based on the rate of regeneration, arm loss just prior to the reproductive season may reduce the reproductive potential of this species.

Chemical and Biological Investigation of the Polar Constituents of the Starfish Luidia clathrata, Collected in the Gulf of Mexico

Ten new [1-10] and three known [11-13] polyhydroxysteroids were isolated, along with four known asterosaponins [14-17], from the starfish Luidia clathrata, collected from the offshore waters of the northern Gulf of Mexico. The EtOH extracts of this starfish showed feeding-deterrent properties against marine fish, and inhibited the settlement of larvae of barnacles and bryozoans, as well as the growth of several bacteria. The structures of the new compounds were determined by interpretation of their nmr spectral data and by comparison with the spectral data of known compounds. The assignment of the configurations of the side-chain stereogenic centers of compounds 1 and 3-10 were based on the comparison of their nmr data with those of the stereoisomeric model compounds after derivatization with the chiral auxiliary MTPA reagent. Larval settlement assays conducted on ten isolated compounds revealed they are all potent inhibitors of settlement. Two of these isolated compounds inhibited the growth of several bacteria.

Shell matrix proteins - a potential tool for investigating the phylogenetic relationships of the Echinodermata

The phylogenetic relationships of the echinoderms remains controversial due to the traditional use of morphological characters which do not reflect convergent evolution. While biochemical techniques and DNA analysis may be used in addition to morphological characters for analysis of living echinoderms, these tools cannot be extended to fossils. Shell matrix proteins - of echinoderms may be trapped and preserved for millions of years in fossil genera.Analysis of shell matrix protein from Astropectin irregularis, Luidia clathrata and Mellita tenuis, reveal the presence of at least three major proteins of approximate molecular weights 230, 83 and 17 kDa common to all species. Astropectin irregularis showed four additional major bands of molecular weights 150, 90, 52 and 35 kDa along with at least 12 minor bands. Luidia clathrata showed five additional major bands of molecular weights 99, 60, 40, 24 and 21 kDa and at least 13 other minor bands. Mellita tenuis showed three additional bands of molecular weights 115, 96, and 24 kDa along with at least 4 minor bands.As the three common proteins have been found in both seastars (A. irregularis and L. clathrata) and echinoids (Mellita tenuis), further analysis of these shell matrix proteins may be used to elucidate phylogenetic relationships within the Echinodermata. In addition homoplasies may be identified and phylogenetically reassessed.

The effect of food ration on the quality of eggs ofLuidia clathrata(Say) (Echinodermata: Asteroidea)

Summary Luidia clathrata fed a low food ration during the gametogenic period had a decrease in the weight of the body and pyloric caeca although gonads were produced. Individuals fed a high food ration during this period had an increase in the weight of the body and pyloric caeca along with gonad production. The eggs of individuals fed the low food ration were significantly although only slightly larger than those of individuals fed the high food ration. The eggs of the former group had a lower fertilizability (21 versus 100%) and a lower survival (50 versus 80%). This indicates that egg size in Luidia clathrata is not greatly affected by food ration, and that egg size is not a good indicator of egg quality for this species. Life history models must consider the effect of food ration on the quality of eggs.

The effect of cations on the specific activities of pyruvate kinase and glucose-6-phosphate dehydrogenase of Luidia clathrata (say) (Echinodermata: Asteroidea)

1. 1. The combined effect of cations (Na +, K +, Ca 2+ and Mg 2+) on the specific activities of pyruvate kinase (PK) and glucose-6-phosphate dehydrogenase (G-6-PDH) were examined in the pyloric caeca, gonads and tube feet of adult Luidia clathrata. 2. 2. Cation concentrations were based on previously determined intracellular values from individuals that had been exposed to 15, 25 and 35% salinity for 1 week. 3. 3. Increases in cationic strength resulted in decreases in specific activity for both enzymes in all tissues. As cationic strength increased, decreases in specific activity were greater for G-6-PDH than PK under similar assay conditions. 4. 4. The relative sensitivity of PK to changes in cation concentration may ensure the stability of the enzyme's catalytic and regulatory functions, while the greater relative sensitivity of G-6-PDH to cations could alter the organism's anabolic capacity.

The Effect of Reproductive State, Temperature, and Salinity on DNA and RNA Levels and Activities of Metabolic Enzymes of the Pyloric Ceca in the Sea Star Luidia clathrata (Say)

During the annual reproductive cycle, the pyloric ceca change in size and synthetic capacity. Changes in the amount of DNA indicated that seasonal changes in the size of the pyloric ceca resulted mainly from changes in the number of cells. The highest concentrations of RNA and the highest RNA:DNA ratios occurred during gametogenesis in the winter; lowest levels and ratios occurred in the summer or during environmental stress. Maximal activities of glucose-6-phosphate dehydrogenase (G-6PDH), 6-phosphogluconate dehydrogenase (6-PGDH), glycerolphosphate dehydrogenase (GPDH), glyceraldehyde-3-phosphate dehydrogenase (G-3-PDH), and pyruvate kinase (PK) occurred during gametogenesis. Exposure of Luidia clathrata to diferent temperatures in the laboratory did not affect the level of activities of G-6PDH, 6-PGDH, GPDH, and PK when measured at a constant temperature or concentrations of nucleic acids in the pyloric ceca. Activities of 6-PGDH, GPDH, and PK decreased, the concentration of DNA increased, and the concentration of RNA decreased in individuals exposed to low salinity. This resulted from decreased food intake and an apparent increase in the metabolic cost of cell-volume regulation. The significant efects of combinations of environmental factors indicate their importance when cellular responses during the reproductive cycle of L. clathrata are interpreted.

The effect of temperature and salinity interactions on righting, feeding and growth in the sea starLuidia clathrata(SAY)

In the field, Luidia clathrata are exposed to seasonal variations in temperature and salinity ranging from 12–31°C and 13–28‰ S. In the laboratory, righting ability and feeding rates decreased in individuals exposed to low temperature (17°C) for 30 days and showed little or no acclimation. Righting ability, feeding, total wet weight and pyloric caecal weight decreased in individuals exposed to low salinity (16‰). The latter two responses resulted from decreased food intake and an apparent increase in the metabolic cost of cell volume regulation. Although L. clathrata can acclimate partially to this low salinity, their condition deteriorated with chronic exposure. Changes in the levels and interactions of temperature, salinity and food had a greater influence on the responses of L. clathrata than changes in only one factor. Combinations of high or low temperatures and low salinity had a negative effect on righting, feeding and growth. The significant effects of combinations of environmental factors on organismal and physiological responses in the laboratory indicate their importance when interpreting the responses of individuals in the field.

The Effect of 17 β-Estradiol and Estrone on Intermediary Metabolism of the Pyloric Caeca of the Asteroid Luidia clathrata (Say) Maintained under Different Nutritional Regimes.

Luidia clathrata were fed either a high or low level of food and injected with estradiol, estrone, or seawater for 16 days. In individuals maintained at a low level of food, the weight of the pyloric caeca decreased in all individuals, regardless of hormone injections. Activities of all enzymes in these individuals were lower than in individuals maintained at a high level of food. In the individuals maintained at a low level of food, the activity of GPDH was higher in the pyloric caeca of individuals injected with estradiol and estrone than in those receiving seawater injections; the activity of 6-PGDH decreased in those injected with estrone. In individuals maintained at a high level of food, the activities of glucose-6-phosphate dehydrogenase (G-6-PDH) and 6-phosphogluconate dehydrogenase (6-PGDH) were higher in individuals injected with estradiol than in those receiving seawater injections. Activities of glycerol phosphate dehydrogenase (GPDH) and pyruvate kinase (PK) were not affected. A slight decrease (P<0.1) in the activity of 6-PGDH was seen with injection of estrone. These results suggest that steroids have a role in regulating cellular metabolism in the pyloric caeca, and that nutritional condition influences the response of the pyloric caeca to steroids. In addition, these results indicate that the nutritional condition of the individual directly influences enzyme activities.