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  • 1
    Electronic Resource
    Electronic Resource
    Depletion of hypothalamic norepinephrine reduces the fever induced by polyriboinosinic acid: polyribocytidylic acid (Poly I:Poly C) in rats (1989)
    Springer
    Cellular and molecular life sciences 45 (1989), S. 720-722 
    Details
    ISSN: 1420-9071
    Keywords: Hypothalamus ; norepinephrine ; fever ; pyrogen ; polyriboinosinic acid ; polyribocytidylic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Administration of either Poly I:Poly C (0.05–0.50 μg) or norepinephrine (2–8 μg) into the anterior hypothalamic area produced a dose-related fever in rats. The fever induced by Poly I:Poly C was attenuated after selective depletion of norepinephrine in the hypothalamus. However, selective depletion of hypothalamic norepinephrine did not affect the fever induced by intrahypothalamic norepinephrine. The data indicate that Poly I:Poly C may act to induce fever through the endogenous release of norepinephrine from the rat's hypothalamus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974567
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  • 2
    Electronic Resource
    Electronic Resource
    Behaviour of echinoid larvae around sharp haloclines: effects of the salinity gradient and dietary conditioning (1998)
    Springer
    Marine biology 131 (1998), S. 443-459 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined larval response to a range of sharp haloclines and determined the effect of dietary conditioning on that response in the sea urchins Echinometra lucunter and Arbacia punctulata. We reared larvae in the laboratory under a high or low concentration of either single (Isochrysis galbana) or mixed (Isochrysis galbana, Dunaliella tertiolecta, Thalassiosira weissflogii) microalgal species. For both species of sea urchins, rate of larval development was faster and age-specific larval length and width were greater in high-ration than low-ration diets. We examined the distribution of two- and four-arm larvae of E. lucunter from each diet treatment and of four-arm larvae of A. punctulata from the high-ration diets in cylinders with experimentally constructed haloclines. In three of the halocline treatments, the salinity of the bottom layer was 33‰ and that of the top layer was 21, 24 or 27‰ (21/33, 24/33 and 27/33) and in a fourth one, the salinities of the bottom and top layer were 30 and 21‰, respectively (21/30). The position of larvae in the cylinders varied with the steepness of the halocline and with dietary conditioning for both sea urchin species and all developmental stages tested. Significantly more larvae crossed the haloclines into water of 24 and 27‰ salinity than into water of 21‰ salinity. We observed an effect of diet on the position of larvae in the cylinders, and that effect varied among halocline treatments for both species. The proportion of larvae of E.lucunter that crossed the halocline was greater in low- than high-ration diets in the 24/33 and 27/33 treatments. Position of four-arm larvae in the cylinders also varied with food quality in high-ration diets: for E.lucunter in the 24/33 treatments, and for A. punctulata in the 21/30 treatments, more larvae from the single- than from the mixed-species diets were present above the halocline. Salinity in the adult habitat during most of the active reproductive period ranged from 15 to 40‰. We showed that larvae can respond to gradients in salinity, and therefore can remain within a water mass of higher salinity overlying the adult habitat. However, survival of poorly fed larvae may be increased if they are introduced into a new water mass and carried away from a nutritionally poor environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050337
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  • 3
    Electronic Resource
    Electronic Resource
    Factors controlling spatial distribution of the sea cucumber Psolus chitonoides: Settling and post-settling behavior (1982)
    Springer
    Marine biology 69 (1982), S. 195-205 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Substratum selection experiments were carried out in situ with larvae of the holothurian Psolus chitonoides Clark in the rocky subtidal of the San Juan Islands, Washington. The experiments indicated, in agreement with laboratory findings, that pentactula larvae settle gregariously, either on the adult, or (when the bivium is obscured by epizooites) by clustering around the margin of the adult sole. Late larvae and early juveniles are strongly photonegative. Following metamorphosis, juveniles migrate from the adults into nearby shaded habitats, where they may take up residence indefinitely. Although adults retain the capacity to move, they relocate only when their living conditions become unsuitable; in most circumstances they are effectively sessile. Small-scale spatial pattern of the adults, which was documented quantitatively on subtidal rock walls, boulders and cobbles, correlates well with microtopographical features. The aggregation observed in the field is primarily due to post-settling migration rather than larval substratum choice at settlement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396899
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  • 4
    Electronic Resource
    Electronic Resource
    Larval depletion by ascidians has little effect on settlement of epifauna (1989)
    Springer
    Marine biology 102 (1989), S. 481-489 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ascidian densities were manipulated while controlling for negative effects of biodeposition and space preemption to examine the effects of ascidian filter-feeding on larval recruitment in St. Joseph Bay and near Turkey Point, Florida (Northern Gulf of Mexico, Florida, USA). Using three different experimental designs during 1984 and 1985, recruitment near living Styela plicata or Molgula occidentalis was as high as recruitment near ascidian models. Disruption of flow by ascidian bodies had little effect on settlement. Predation rates by ascidians on larvae in six phyla were high in laboratory experiments. The field effects of larval depletion by solitary ascidians are apparently obscured by other factors influencing the abundance of recruiting larvae. Consumption of larvae in the laboratory cannot be used to assume significant inhibitory effects in the field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00438349
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  • 5
    Electronic Resource
    Electronic Resource
    Feeding mechanism of the brisingid starfish Novodinia antillensis (1994)
    Springer
    Marine biology 118 (1994), S. 433-442 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper describes the food and feeding mechanisms of the bathyal brisingid sea-star Novodinia antillensis (A. H. Clark, 1934). N. antillensis is shown to be an opportunistic suspension feeder capable of capturing living planktonic crustaceans of a wide range of sizes. The sea-star extends its 10 to 14 arms into water currents to form a feeding fan with a large surface area, and uses highly retentive pedicellaria on the lateral arm spines to grasp and retain prey. The flexible arms form arm loops to complete the capture. The pedicellaria have a structure very similar to that used by other species known to capture macroscopic prey and, although they are an order of magnitude smaller, they probably function in a similar manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350300
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  • 6
    Electronic Resource
    Electronic Resource
    Biochemical and energetic composition of bathyal echinoids and an asteroid, holothuroid and crinoid from the Bahamas (1990)
    Springer
    Marine biology 105 (1990), S. 175-183 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The biochemical and energetic composition of body components of ten species of bathyal echinoids, and an asteroid, a holothuroid and a stalked crinoid were determined from individuals sampled from a variety of deep-water sites near the Bahamas (north Caribbean Sea) in October 1988. When compared with other studies of echinoderms, no geographic- or depth-related differences in biochemical or energetic composition were found. Body-wall tissues were composed primarily of skeletal material (mineral ash), but were comparatively high in organic material in the echinothuriid echinoids, and the asteroid and holothuroid. Gut tissues and pyloric cecae had high levels of lipid and protein, indicating their potential role in nutrient storage. Body-wall tissues were generally low in energy, but were highest in the echinoidsAraeosoma belli (7.7 kJ g−1 dry wt) andSperosoma antillense (8.0 kJ g−1 dry wt), the asteroidOphidiaster alexandri (8.9 kJ g−1 dry wt), and the holothuroidEostichopus regalis (13.1 kJ g−1 dry wt). Energy levels of gut and pyloric cecal tissues were two to three times higher than those of body-wall tissues. Total somatic tissue energy values varied greatly among species, ranging from 1.5 kJ in the echinoidAspidodiadema jacobyi to 142.1 kJ inE. regalis. As the bathyal echinoderms examined in this study occur in great abundance, they represent a significant reservoir of organic and inorganic materials and energy in deep-water benthic systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01344284
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of sponges on invertebrate recruitment: A field test of allelopathy (1991)
    Springer
    Marine biology 109 (1991), S. 19-26 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We manipulated live sponges in Belize, Central America, Big Pine Key, Florida (USA), and Indian River lagoon, Florida (USA) in summer/autumn, 1988. At each location, live sponges of three species were placed within 0.5 cm of ceramic tiles. Tiles with synthetic sponges positioned in the same manner and tiles with no sponges served as controls. Of 26 recruiting species analyzed, only one (Sponge sp. 6 — Indian River) was inhibited by living sponges. Four species (Perophora regina — Belize;Aiptasia pallida — Big Pine Key; andCrassostrea virginica andAscidia nigra — Indian River) recruited in greater numbers in the presence of sponges, suggesting that some larvae may be attracted rather than repelled by sponge allelochemicals. Allelopathic effects were less important than small-scale flow effects and patchy larval supply in determining recruitment patterns on surfaces adjacent to sponges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01320227
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  • 8
    Electronic Resource
    Electronic Resource
    Seasonal breeding aggregations in low-density populations of the bathyal echinoid Stylocidaris lineata (1992)
    Springer
    Marine biology 113 (1992), S. 603-612 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Reproduction of bathyal cidaroid sea urchins was studied between 1985 and 1991 with the aid of a manned submersible in the northern Bahamas. During May 1988 and February 1990, discrete, single-species aggregations of Stylocidaris lineata containing 2 to 6 individuals were observed between 510 and 640 m depths. Reproductive conditions of isolated and aggregated individuals were determined histologically. In February, all individuals, regardless of their spatial distribution, contained developing gametes. During the May spawning season, most isolated individuals contained spent gonads with only relict gametes, whereas individuals in discrete aggregations mostly contained ripe gonads with mature or nearly-mature gametes. Aggregations were not observed during the autumn months, when gonads were spent or immature. These data suggest that bathyal cidaroids aggregate for reproduction. An in situ survey during May indicated that pairs of S. lineata are more common than larger clumps, but no more so than predicted by chance. Homosexual and heterosexual pairs occur at the relative frequencies predicted on the basis of sex ratio. We evaluated the need for reproductive aggregation by applying Denny's (1988) model that predicts downstream sperm concentration in a turbulent boundary layer. Flow parameters were measured with dye injected from the submersible, sperm-release rate was estimated in the laboratory, and the relationship between fertilization success and sperm concentration was determined in a laboratory dilution-experiment. The model predicted that, on smooth sandy bottoms at bathyal depths, sperm concentration should remain high enough to fertilize at least some eggs several meters directly downstream from a spawning male. Aggregation may facilitate spawning synchrony, increase gamete encounter probabilities, or cause gametes to be retained at high concentrations near the adults long enough for fertilization to occur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349704
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  • 9
    Electronic Resource
    Electronic Resource
    Responses of echinoid larvae to food patches of different algal densities (1998)
    Springer
    Marine biology 130 (1998), S. 433-445 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract High densities of larvae have been found in areas of high primary production, but it remains unclear whether this is the result of hydrodynamics or of larval aggregative behaviour in the presence of food. In this study, we examined changes in the vertical distribution and swimming patterns of four-armed larvae of the sea-urchin Echinometra lucunter (Linnaeus) around food patches of a range of microalgal densities. We reared larvae in the laboratory in a high or low concentration of either single (Isochrysis galbana) or mixed (I. galbana, Dunaliella tertiolecta, Thalassiosira weissflogii) microalgal species. In Plexiglas cylinders, we experimentally constructed haloclines in which the salinity of the bottom water-layer was 33‰ and that of the top water-layer was 24‰. In a thin layer in the middle of the halocline, we inserted a food patch that consisted of 0, 2500, 5000 or 10 000 T. weissflogii cells ml−1. The presence of a food patch had a pronounced effect on the vertical distribution of larvae. This effect depended upon the algal density of the food patch and varied with dietary conditioning. The number of larvae that were above or within the patch decreased with increasing algal density, and was greater if larvae were reared in low-ration or single-species diets than in high-ration or mixed-species diets. Tracking of individual vertical swimming paths showed that within a few minutes, larvae swam into the patches of low algal density, and to positions just below the patches of the two higher algal densities, and remained there until the end of the experimental period. The greater number of algal cells in the digestive tracts of larvae from treatments with a food patch than in those without a patch confirmed that larvae were feeding on the microalgal cells of the patch. To our knowledge, this is the first study to experimentally show an aggregative behavioural response of invertebrate larvae to a food patch. Such a response may reduce the probability of food limitation and therefore enhance larval survival.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050264
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrastructure of gametogenesis in a chemosynthetic mytilid bivalve (Bathymodiolus childressi ) from a bathyal, methane seep environment (northern Gulf of Mexico) (1999)
    Springer
    Marine biology 135 (1999), S. 635-646 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructural features of gametogenesis have been described in the methane-seep mytilid bivalve Bathymodiolus childressi Gustafson, Turner, Lutz & Vrijenhoek, 1998 collected from the Gulf of Mexico in August 1995. This is the first ultrastructural description of gametogenesis in any methane-seep bivalve. B. childressi is gonochoric, and both the testis and ovary consist of acini surrounded by inter-acinal tissue composed of adipogranular cells that serve a nutrient storage function. Oocytes develop in close association with squamous follicle cells although the follicle cells do not appear to play a primary role in yolk synthesis. During the vitellogenic phase, biosynthesis of four types of organelles occurs, including lipid droplets, yolk granules, cortical granules, and unknown inclusions, which are exocytosed as part of egg envelope biogenesis. Vitellogenesis appears to be largely autosynthetic involving the Golgi complex and rough endoplasmic reticulum. Sperm differentiation resembles that reported in other mytilid bivalves and includes the differentiation of proacrosomal granules and a flagellum during the early stages of spermatogenesis. Mature sperm have a cap-like acrosome, substantial subacrosomal material, a bullet-shaped nucleus, and four to five mitochondria in the midpiece. The general features of gametogenesis closely resemble those reported in shallow-water, seasonally reproducing mytilids. Despite the relatively stable methane seep environment and presumed continuous availability of nutrients, reproduction parallels that of littoral mytilids, suggesting some phylogenetic constraints on the capacity for variability in gametogenic processes in the family Mytilidae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050664
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