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Sample records for female silver eels

  1. Swimming suppresses hepatic vitellogenesis in European female silver eels as shown by expression of the estrogen receptor 1, vitellogenin1 and vitellogenin2 in the liver

    PubMed Central

    2010-01-01

    Background When European silver eels (Anguilla anguilla) venture into the Atlantic Ocean for their 6,000 km semelparous spawning run to the Sargasso Sea, they are still in a prepubertal stage. Further sexual development appears to be blocked by dopaminergic inhibition of hypothalamus and pituitary activity. Recently, we found that swimming for several weeks in freshwater stimulated the incorporation of fat droplets in the oocytes. So, it was hypothesized that long term swimming in seawater would release the inhibition further and would also stimulate the production of vitellogenin by the liver. Methods For this study a swim-flume was constructed to allow simulated migration of migratory female silver eels for 3 months (1,420 km) in natural seawater at 20 degrees C. Primers were designed for polymerase chain reactions to measure the mRNA expression of estrogen receptor 1 (esr1), vitellogenin1 (vtg1) and vitellogenin2 (vtg2) genes in the liver of European female silver eels. Results In comparison to resting eels, swimming eels showed a diminished expression of esr1, vtg1 and vtg2 in the liver. They also had lower plasma calcium (Ca; indicative of vitellogenin) levels in their blood. This showed that vitellogenesis is more strongly suppressed in swimming than in resting eels. However, when eels were subsequently stimulated by 3 weekly carp pituitary extract injections, the expression of the same genes and plasma levels of Ca strongly increased in both groups to similar levels, thus equalizing the initial differences between resting and swimming. Conclusions It is concluded that vitellogenesis remains suppressed during resting and even more during swimming. The fact that swimming stimulates fat deposition in the oocytes but suppresses vitellogenesis indicates that these events are separated in nature and occur sequentially. Swimming-suppressed vitellogenesis may imply that in nature eels undergo vitellogenesis and final maturation near or at the spawning grounds. PMID

  2. Gonadal transcriptome analysis of wild contaminated female European eels during artificial gonad maturation.

    PubMed

    Baillon, Lucie; Oses, Jennifer; Pierron, Fabien; Bureau du Colombier, Sarah; Caron, Antoine; Normandeau, Eric; Lambert, Patrick; Couture, Patrice; Labadie, Pierre; Budzinski, Hélène; Dufour, Sylvie; Bernatchez, Louis; Baudrimont, Magalie

    2015-11-01

    Since the early 1980s, the population of European eels (Anguilla anguilla) has dramatically declined. Nowadays, the European eel is listed on the red list of threatened species (IUCN Red List) and is considered as critically endangered of extinction. Pollution is one of the putative causes for the collapse of this species. Among their possible effects, contaminants gradually accumulated in eels during their somatic growth phase (yellow eel stage) would be remobilized during their reproductive migration leading to potential toxic events in gonads. The aim of this study was to investigate the effects of organic and inorganic contaminants on the gonad development of wild female silver eels. Female silver eels from two sites with differing contamination levels were artificially matured. Transcriptomic analyses by means of a 1000 candidate gene cDNA microarray were performed on gonads after 11weeks of maturation to get insight into the mechanisms of toxicity of contaminants. The transcription levels of several genes, that were associated to the gonadosomatic index (GSI), were involved in mitotic cell division but also in gametogenesis. Genes associated to contaminants were mainly involved in the mechanisms of protection against oxidative stress, in DNA repair, in the purinergic signaling pathway and in steroidogenesis, suggesting an impairment of gonad development in eels from the polluted site. This was in agreement with the fact that eels from the reference site showed a higher gonad growth in comparison to contaminated fish. PMID:26159298

  3. Effects of high-pressure acclimatization on silver eel (Anguilla anguilla, L.) slow muscle contraction.

    PubMed

    Rossignol, Orlane; Sebert, Philippe; Simon, Bernard

    2006-02-01

    As the spawning migration of the eel is supposed to correspond to a long swimming activity at depth, patterns of slow red muscle contraction have been investigated in European silver eel (Anguilla anguilla L.) exposed for 3 weeks to 10.1 MPa hydrostatic pressure. The results show that pressure-acclimated eels (male and female) show a three-fold decrease in maximum isometric stress of twitch and tetanic contractions while time to peak force, time from peak force to 90% relaxation and ratio of twitch tension to tetanic tension remain unchanged. The observed modifications in slow red muscle mechanical properties do not impede the spawning migration of the eel and are possibly partially compensated by an improvement in the efficiency of oxidative phosphorylation. Effects of changes in membrane fluidity are also discussed. PMID:16413804

  4. Simulating the Oceanic Migration of Silver Japanese Eels.

    PubMed

    Chang, Yu-Lin; Miyazawa, Yasumasa; Béguer-Pon, Mélanie

    2016-01-01

    The oceanic migration of silver Japanese eels starts from their continental growth habitats in East Asia and ends at the spawning area near the West Mariana Ridge seamount chain. However, the actual migration routes remain unknown. In this study, we examined the possible oceanic migration routes and strategies of silver Japanese eels using a particle tracking method in which virtual eels (v-eels) were programmed to move vertically and horizontally in an ocean circulation model (Japan Coastal Ocean Predictability Experiment 2, JCOPE2). Four horizontal swimming strategies were tested: random heading, true navigation (readjusted heading), orientation toward the spawning area (fixed heading), and swimming against the Kuroshio. We found that all strategies, except random swimming, allowed v-eels swimming at 0.65 m s-1 to reach the spawning area within eight months after their departure from the south coast of Japan (end of the spawning season). The estimated minimum swimming speed required to reach the area spawning within eight months was 0.1 m s-1 for true navigation, 0.12 m s-1 for constant compass heading, and 0.35 m s-1 for swimming against the Kuroshio. The lowest swimming speed estimated from tracked Japanese eels at sea was 0.03 m.s-1, which would not allow them to reach the spawning area within eight months, through any of the tested orientation strategies. Our numerical experiments also showed that ocean circulation significantly affected the migration of Japanese v-eels. A strong Kuroshio could advect v-eels further eastward. In addition, western Pacific ocean currents accelerated the migration of navigating v-eels. The migration duration was shortened in years with a stronger southward flow, contributed by a stronger recirculation south of Japan, an enhanced subtropical gyre, or a higher southward Kuroshio velocity. PMID:26982484

  5. Simulating the Oceanic Migration of Silver Japanese Eels

    PubMed Central

    Chang, Yu-Lin; Miyazawa, Yasumasa; Béguer-Pon, Mélanie

    2016-01-01

    The oceanic migration of silver Japanese eels starts from their continental growth habitats in East Asia and ends at the spawning area near the West Mariana Ridge seamount chain. However, the actual migration routes remain unknown. In this study, we examined the possible oceanic migration routes and strategies of silver Japanese eels using a particle tracking method in which virtual eels (v-eels) were programmed to move vertically and horizontally in an ocean circulation model (Japan Coastal Ocean Predictability Experiment 2, JCOPE2). Four horizontal swimming strategies were tested: random heading, true navigation (readjusted heading), orientation toward the spawning area (fixed heading), and swimming against the Kuroshio. We found that all strategies, except random swimming, allowed v-eels swimming at 0.65 m s−1 to reach the spawning area within eight months after their departure from the south coast of Japan (end of the spawning season). The estimated minimum swimming speed required to reach the area spawning within eight months was 0.1 m s−1 for true navigation, 0.12 m s−1 for constant compass heading, and 0.35 m s−1 for swimming against the Kuroshio. The lowest swimming speed estimated from tracked Japanese eels at sea was 0.03 m.s−1, which would not allow them to reach the spawning area within eight months, through any of the tested orientation strategies. Our numerical experiments also showed that ocean circulation significantly affected the migration of Japanese v-eels. A strong Kuroshio could advect v-eels further eastward. In addition, western Pacific ocean currents accelerated the migration of navigating v-eels. The migration duration was shortened in years with a stronger southward flow, contributed by a stronger recirculation south of Japan, an enhanced subtropical gyre, or a higher southward Kuroshio velocity. PMID:26982484

  6. Selection of best-performing reference gene products for investigating transcriptional regulation across silvering in the European eel (Anguilla anguilla)

    PubMed Central

    Franzellitti, Silvia; Kiwan, Alisar; Valbonesi, Paola; Fabbri, Elena

    2015-01-01

    The focus of the present study was to set a methodological approach for evaluating molecular mechanisms underlying silvering transformation in the European eel, Anguilla anguilla. Silvering is a tightly controlled process during which eels undergo significant morphological, physiological and behavioral changes, pre-adapting for the oceanic spawning migration. Female eels showing different silver indexes were caught in different seasons in the Comacchio Lagoon (North Adriatic Sea, Italy). Isolated hepatocytes from these eels were selected as the experimental model given the relevant role of these cells in metabolic functions potentially altered during silvering. Expression profiles of 7 candidate reference transcripts were analyzed seeking the most viable and robust strategies for accurate qPCR data normalization during silvering. Stability analysis and further statistical validation identified transcripts encoding the ribosomal proteins L13 and ARP as the appropriate reference genes in studies on A. anguilla through silvering. The identified reference transcripts were further used to evaluate expression profiles of target transcripts encoding the thyroid hormone receptor β (THRβ) and vitellogenin (vtg), known to be involved in silvering processes. To the best of our knowledge, this is the first study comparing THRβ expression in European eels across silvering. PMID:26593703

  7. Selection of best-performing reference gene products for investigating transcriptional regulation across silvering in the European eel (Anguilla anguilla).

    PubMed

    Franzellitti, Silvia; Kiwan, Alisar; Valbonesi, Paola; Fabbri, Elena

    2015-01-01

    The focus of the present study was to set a methodological approach for evaluating molecular mechanisms underlying silvering transformation in the European eel, Anguilla anguilla. Silvering is a tightly controlled process during which eels undergo significant morphological, physiological and behavioral changes, pre-adapting for the oceanic spawning migration. Female eels showing different silver indexes were caught in different seasons in the Comacchio Lagoon (North Adriatic Sea, Italy). Isolated hepatocytes from these eels were selected as the experimental model given the relevant role of these cells in metabolic functions potentially altered during silvering. Expression profiles of 7 candidate reference transcripts were analyzed seeking the most viable and robust strategies for accurate qPCR data normalization during silvering. Stability analysis and further statistical validation identified transcripts encoding the ribosomal proteins L13 and ARP as the appropriate reference genes in studies on A. anguilla through silvering. The identified reference transcripts were further used to evaluate expression profiles of target transcripts encoding the thyroid hormone receptor β (THRβ) and vitellogenin (vtg), known to be involved in silvering processes. To the best of our knowledge, this is the first study comparing THRβ expression in European eels across silvering. PMID:26593703

  8. Influence of introduced vs. native parasites on the body condition of migrant silver eels

    PubMed Central

    Gérard, Claudia; Trancart, Thomas; Amilhat, Elsa; Faliex, Elisabeth; Virag, Laure; Feunteun, Eric; Acou, Anthony

    2013-01-01

    Because parasitism is among the reasons invoked to explain the collapse of Anguilla anguilla, we evaluated the parasitic constraint on body condition (BC) of migrant silver eels as a proxy of fitness with inter-site comparisons. Metazoan parasites were studied in 149 silver eels from five sites (northern Europe). In total, 89% were infected by 13 species including Myxozoa, Monogenea, Cestoda, Nematoda, and Acanthocephala. Anguillicoloides crassus was most common (56%), then Acanthocephalus clavula (30%), and Pseudodactylogyrus sp. (17%). BC, calculated for 58 females, was negatively correlated by abundance of the introduced Pseudodactylogyrus sp. but not by other parasite taxa. Nevertheless, the introduced A. crassus was considered as a severe pathogen based on previous data, whereas the native A. clavula was supposed to have limited impact. Parasite component communities and BC were different between sites. Silver eels from Stockholm Archipelago (Sweden) were the least parasitized (40% vs. 90–95% for other sites) with no parasites on the gills. Burrishoole (Ireland) differed by the absence of A. crassus and high prevalence of A. clavula (84%) but without consequences on BC. Gudenaa (Denmark), Corrib (Ireland), and Frémur (France) were close due to high prevalence of A. crassus (89–93%). Gudenaa and Corrib were the most similar because Pseudodactylogyrus sp. was also highly prevalent (respectively 71% and 60%) whereas absent in Frémur. Our results suggest that the fitness loss induced by the introduced parasites could affect the spawning success of migrant silver eels from Gudenaa and Corrib, and to a lesser extent from Frémur, but probably not those from Stockholm Archipelago and Burrishoole. PMID:24135272

  9. Migration behaviour of silver eels (Anguilla anguilla) in a large estuary of Western Europe inferred from acoustic telemetry

    NASA Astrophysics Data System (ADS)

    Bultel, Elise; Lasne, Emilien; Acou, Anthony; Guillaudeau, Julien; Bertier, Christine; Feunteun, Eric

    2014-01-01

    Despite intensive research on eels, the behaviour of silver eels in estuaries during their migration remains poorly documented which creates serious gaps in planning the restoration of the European eel population. Estuaries are complex environments that can be exposed to large human pressures which could impede, delay migration or impact fish reproductive potential. This study investigated the estuarine migration of female silver eels in the Loire River using an acoustic telemetry system. An array of 31 hydrophones was deployed in the Loire estuary and 51 female seaward migrants were tagged with acoustic transmitters and released 20 km upstream of the estuary, at 100 km from the river mouth. 94% of the silver eels could be followed down to the river mouth. Mean global estuarine speed was 4.5 km days-1, i.e., 0.05 m s-1 and residence times varied significantly between upstream and lower compartments. Mean directional migration speed was found to be 48.6 km days-1, i.e., 0.56 m s-1, and appeared correlated with total length and body weight. Also, daily escapement rate was highly influenced by river flow.

  10. Freshwater and coastal migration patterns in the silver-stage eel Anguilla anguilla.

    PubMed

    Barry, J; Newton, M; Dodd, J A; Lucas, M C; Boylan, P; Adams, C E

    2016-02-01

    The unimpeded downstream movement patterns and migration success of small female and male Anguilla anguilla through a catchment in north-west Europe were studied using an acoustic hydrophone array along the River Finn and into the Foyle Estuary in Ireland. Twenty silver-stage A. anguilla (total length, LT , range: 332-520 mm) were trapped 152 km upstream from a coastal marine sea-lough outlet and internally tagged with acoustic transmitters of which 19 initiated downstream migration. Migration speed was highly influenced by river flow within the freshwater (FW) compartment. Anguilla anguilla activity patterns were correlated with environmental influences; light, tidal direction and lunar phase all influenced the initiation of migration of tagged individuals. Migration speed varied significantly between upstream and lower river compartments. Individuals migrated at a slower speed in transitional water and sea-lough compartments compared with the FW compartment. While 88·5% survival was recorded during migration through the upper 121 km of the river and estuary, only 26% of A. anguilla which initiated downstream migration were detected at the outermost end of the acoustic array. Telemetry equipment functioned efficiently, including in the sea-lough, so this suggests high levels of mortality during sea-lough migration, or less likely, long-term sea-lough residence by silver A. anguilla emigrants. This has important implications for eel management plans. PMID:26707686

  11. Swimming physiology of European silver eels (Anguilla anguilla L.): energetic costs and effects on sexual maturation and reproduction.

    PubMed

    Palstra, Arjan P; van den Thillart, Guido E E J M

    2010-09-01

    The European eel migrates 5,000-6,000 km to the Sargasso Sea to reproduce. Because they venture into the ocean in a pre-pubertal state and reproduce after swimming for months, a strong interaction between swimming and sexual maturation is expected. Many swimming trials have been performed in 22 swim tunnels to elucidate their performance and the impact on maturation. European eels are able to swim long distances at a cost of 10-12 mg fat/km which is 4-6 times more efficient than salmonids. The total energy costs of reproduction correspond to 67% of the fat stores. During long distance swimming, the body composition stays the same showing that energy consumption calculations cannot be based on fat alone but need to be compensated for protein oxidation. The optimal swimming speed is 0.61-0.67 m s(-1), which is approximately 60% higher than the generally assumed cruise speed of 0.4 m s(-1) and implies that female eels may reach the Sargasso Sea within 3.5 months instead of the assumed 6 months. Swimming trials showed lipid deposition and oocyte growth, which are the first steps of sexual maturation. To investigate effects of oceanic migration on maturation, we simulated group-wise migration in a large swim-gutter with seawater. These trials showed suppressed gonadotropin expression and vitellogenesis in females, while in contrast continued sexual maturation was observed in silver males. The induction of lipid deposition in the oocytes and the inhibition of vitellogenesis by swimming in females suggest a natural sequence of events quite different from artificial maturation protocols. PMID:20390348

  12. Temporal expression of hepatic estrogen receptor 1, vitellogenin1 and vitellogenin2 in European silver eels.

    PubMed

    Palstra, Arjan P; Schnabel, Denhi; Nieveen, Maaike C; Spaink, Herman P; van den Thillart, Guido E E J M

    2010-03-01

    Because European silver eels have never been caught during or after their 6000-km reproductive migration to the Sargasso Sea, all existing knowledge on their sexual maturation comes from hormonal stimulation. Silver eels that start their oceanic migration are still immature with pre-vitellogenic oocytes. Hence we assumed that vitellogenesis should start with the expression of the estrogen receptor in the liver before the circulating 17beta-estradiol (E2) can have any effect. In this study we followed the hepatic vitellogenesis upon 4 weekly injections with carp pituitary extracts (CPE). New molecular primers for the expression of the estrogen receptor 1 (esr1), vitellogenin1 (vtg1) and vitellogenin2 (vtg2) in the liver were developed. Sequences of vtg2 and esr1 were not previously described in Anguilla anguilla. All eels showed weekly increase of the eye size and pectoral fin length, which are signs of early maturation. The same occurred with the gonadosomatic index, the oocyte stage and diameter, and number of deposited fat droplets. Early vitellogenesis appeared as a 3-step process (1) E2-levels and esr1 expression were significantly increased already after one injection, (2) vtg1 and vtg2 expression were significantly increased after one and two injections, respectively, and (3) vtg1 and vtg2 expression increased further after three and four injections. Then also plasma calcium (corresponds with plasma vitellogenin) increased and yolk globuli appeared in the oocytes. These results show that esr1 is the first of the three genes examined that is expressed during the onset of hepatic vitellogenesis. Furthermore, ovarian vitellogenesis (appearance of yolk globuli in oocytes) occurs 1-2 weeks later than the onset of hepatic vitellogenesis. PMID:19766647

  13. High Resolution STEM-EELS Study of Silver Nanoparticles Exposed to Light and Humic Substances.

    PubMed

    Römer, Isabella; Wang, Zhi Wei; Merrifield, Ruth C; Palmer, Richard E; Lead, Jamie

    2016-03-01

    Nanoparticles (NPs) are defined as particles with at least one dimension between 1 and 100 nm or with properties that differ from their bulk material, which possess unique properties. The extensive use of NPs means that discharge to the environment is likely increasing, but fate, behavior, and effects under environmentally relevant conditions are insufficiently studied. This paper focuses on the transformations of silver nanoparticles (AgNPs) under simulated but realistic environmental conditions. High resolution aberration-corrected scanning transmission electron microscopy (HAADF STEM) coupled with electron energy loss spectroscopy (EELS) and UV-vis were used within a multimethod approach to study morphology, surface chemistry transformations, and corona formation. Although loss, most likely by dissolution, was observed, there was no direct evidence of oxidation from the STEM-EELS. However, in the presence of fulvic acid (FA), a 1.3 nm oxygen-containing corona was observed around the AgNPs in water; modeled data based on the HAADF signal at near atomic resolution suggest this was an FA corona was formed and was not silver oxide, which was coherent (i.e., fully coated in FA), where observed. The corona further colloidally stabilized the NPs for periods of weeks to months, dependent on the solution conditions. PMID:26792384

  14. Accumulation of neurotoxic organochlorines and trace elements in brain of female European eel (Anguilla anguilla).

    PubMed

    Bonnineau, C; Scaion, D; Lemaire, B; Belpaire, C; Thomé, J-P; Thonon, M; Leermaker, M; Gao, Y; Debier, C; Silvestre, F; Kestemont, P; Rees, J-F

    2016-07-01

    Xenobiotics such as organochlorine compounds (OCs) and metals have been suggested to play a significant role in the collapse of European eel stocks in the last decades. Several of these pollutants could affect functioning of the nervous system. Still, no information is so far available on levels of potentially neurotoxic pollutants in eel brain. In present study, carried out on female eels caught in Belgian rivers and canals, we analyzed brain levels of potentially-neurotoxic trace elements (Ag, Al, As, Cd, Co, Cr, Cu, Fe, Hg, MeHg, Mn, Ni, Pb, Sn, Sb, Zn) and OCs (Polychlorinated biphenyls, PCBs; Hexachlorocyclohexanes, HCHs; Dichlorodiphenyltrichloroethane and its metabolites, DDTs). Data were compared to levels in liver and muscle tissues. Eel brain contained very high amounts of OCs, superior to those found in the two other tissues. Interestingly, the relative abundance of PCB congeners markedly differed between tissues. In brain, a predominance of low chlorinated PCBs was noted, whereas highly chlorinated congeners prevailed in muscle and liver. HCHs were particularly abundant in brain, which contains the highest amounts of β-HCH and ϒ-HCH. p,p'-DDTs concentration was similar between brain and muscle (i.e., about twice that of liver). A higher proportion of p,p'-DDT was noticed in brain. Except for Cr and inorganic Hg, all potentially neurotoxic metals accumulated in brain to levels equal to or lower than hepatic levels. Altogether, results indicate that eel brain is an important target for organic and, to a lesser extent, for inorganic neurotoxic pollutants. PMID:27376663

  15. Anguillicola crassus impairs the silvering-related enhancements of the ROS defense capacity in swimbladder tissue of the European eel (Anguilla anguilla).

    PubMed

    Schneebauer, Gabriel; Hanel, Reinhold; Pelster, Bernd

    2016-10-01

    In a process called silvering, European eels prepare for their long-distance migration from European freshwater systems to the Sargasso Sea for reproduction. During this journey, eels perform extended diel vertical migrations, and the concomitant changes in hydrostatic pressure significantly affect the swimbladder, functioning as a buoyancy organ. As the swimbladder is primarily filled with oxygen, the tissue has to cope with extreme hyperoxic conditions, which typically are accompanied by the generation of reactive oxygen species (ROS) and oxidative stress. In addition, since the introduction of the parasitic nematode Anguillicola crassus in the early 1980s, swimbladder function of most of the European eels is impaired by the infection with this parasite. However, the exact pathways to detoxify ROS and how these pathways are affected by silvering or the infection are still unknown. In swimbladder and muscle tissue from uninfected and infected yellow, and from uninfected and infected silver eels, we measured the level of lipid peroxidation, which increases with ROS stress. To assess the capacity of the ROS defense systems, we analyzed the activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and glutathione reductase (GR), and determined the concentration of the antioxidant glutathione (GSH + GSSG). In swimbladder tissue, we found increased concentrations of GSH + GSSG as well as higher activities of SOD, GPx and GR, suggesting that SOD and the glutathione cycle are important for ROS detoxification. Comparing swimbladder tissue of uninfected yellow with uninfected silver eels, the concentration of GSH + GSSG and the activity of SOD were higher after silvering, corresponding with lower levels of lipid peroxidation. Whereas in yellow eels the infection with A. crassus had no effect, in silver eels the capacity to cope with ROS was significantly impaired. In muscle tissue, silvering or the infection only affected the activity of SOD

  16. Pressure and temperature interactions on aerobic metabolism of migrating European silver eel.

    PubMed

    Scaion, D; Belhomme, M; Sébert, P

    2008-12-31

    During their migration for reproduction, European eels have to cope with many environmental factors changes. The main changes concern hydrostatic pressure and temperature that are important environmental and physiological factors when considering life in the deep sea. We focus on the consequences of pressure (from 0.1 to 12.1MPa by 1MPa steps) and temperature (9, 15, 22 degrees C) shifts on the oxygen consumption (MO(2)) at the whole animal level. Because of their morphological differences, we are also interested in males and females to evaluate the best conditions for migration. Firstly, whatever temperature, males present higher aerobic capacities than females at atmospheric pressure. Secondly, an increase in temperature increases the pressure effects in males (synergy) but decreases them in females (opposite effects). We raise the hypothesis that two different migration strategies could be used in the water column in order to reach the breeding area: males could tend to privilege pressure and cold waters (deep water) and females, on the other hand, could opt for warmer temperature surface waters. PMID:18762282

  17. Brominated flame retardants and Dechloranes in European and American eels from glass to silver life stages.

    PubMed

    Sühring, Roxana; Byer, Jonathan; Freese, Marko; Pohlmann, Jan-Dag; Wolschke, Hendrik; Möller, Axel; Hodson, Peter V; Alaee, Mehran; Hanel, Reinhold; Ebinghaus, Ralf

    2014-12-01

    The populations of American (Anguilla rostrata) and European eels (Anguilla anguilla) have been declining rapidly in the last decades. Organic contaminants are suspected to be one of the possible causes for the decline; however, so far there have been few investigations of the uptake of specific compounds by different life cycle stages (e.g. freshwater or marine stage) and how the contamination patterns develop throughout the eel's life cycle. In the present study we measured concentrations of polybrominated diphenylethers (PBDEs), alternate brominated flame retardants (alternate BFRs) and Dechloranes (Decs) in different life stages of European and American eels to compare the contamination patterns and their development throughout the eel's life cycle. In general, concentrations of flame retardants (FRs) were similar to or higher in American than in European eels, and a greater number of FRs were detected. PBDE congeners that are characteristic of the Penta-PBDE formulation were the most abundant FRs in all adult eels as well as American glass eels. In European glass eels the alternate BFR 2,3-dibromopropyl-2,4,6-tribromophenylether (DPTE) and Dechlorane Plus were the dominating FRs, with average concentrations of 1.1±0.31 ng g(-1) ww and up to 0.32 ng g(-1) ww respectively. Of the PBDEs BDE-183 was the most abundant congener in European glass eels. Low concentrations (less than 10% of the total contamination) of Tetra and Penta-PBDEs in juvenile European eels indicated that bans of technical Penta-PBDE in the European Union are effective. Enrichment of PBDEs was observed over the life stages of both European and American eels. However, a greater relative contribution of PBDEs to the sum FR contamination in American eels indicated an on-going exposure to these substances. High contributions of alternate BFRs in juvenile eels indicated an increased use of these substances in recent years. Concentrations seemed to be driven primarily by location, rather than life

  18. Anguillicola crassus Infection Significantly Affects the Silvering Related Modifications in Steady State mRNA Levels in Gas Gland Tissue of the European Eel.

    PubMed

    Pelster, Bernd; Schneebauer, Gabriel; Dirks, Ron P

    2016-01-01

    Using Illumina sequencing, transcriptional changes occurring during silvering in swimbladder tissue of the European eel have been analyzed by comparison of yellow and silver eel tissue samples. Functional annotation analysis based on GO terms revealed significant expression changes in a number of genes related to the extracellular matrix, important for the control of gas permeability of the swimbladder, and to reactive oxygen species (ROS) defense, important to cope with ROS generated under hyperbaric oxygen partial pressures. Focusing on swimbladder tissue metabolism, levels of several mRNA species encoding glucose transport proteins were several-fold higher in silver eels, while enzymes of the glycolytic pathway were not affected. The significantly higher steady state level of a transcript encoding for membrane bound carbonic anhydrase, however, suggested that CO2 production in the pentose phosphate shunt and diffusion of CO2 was of particular importance in silver eel swimbladder. In addition, the mRNA level of a large number of genes related to immune response and to sexual maturation was significantly modified in the silver eel swimbladder. The modification of several processes related to protein metabolism and transport, cell cycle, and apoptosis suggested that these changes in swimbladder metabolism and permeability were achieved by increasing cell turn-over. The impact of an infection of the swimbladder with the nematode Anguillicola crassus has been assessed by comparing these expression changes with expression changes observed between uninfected yellow eel swimbladder tissue and infected silver eel swimbladder tissue. In contrast to uninfected silver eel swimbladder tissue, in infected tissue the mRNA level of several glycolytic enzymes was significantly elevated, and with respect to extracellular matrix, several mucin genes were many-fold higher in their mRNA level. Modification of many immune related genes and of the functional categories "response to

  19. Anguillicola crassus Infection Significantly Affects the Silvering Related Modifications in Steady State mRNA Levels in Gas Gland Tissue of the European Eel

    PubMed Central

    Pelster, Bernd; Schneebauer, Gabriel; Dirks, Ron P.

    2016-01-01

    Using Illumina sequencing, transcriptional changes occurring during silvering in swimbladder tissue of the European eel have been analyzed by comparison of yellow and silver eel tissue samples. Functional annotation analysis based on GO terms revealed significant expression changes in a number of genes related to the extracellular matrix, important for the control of gas permeability of the swimbladder, and to reactive oxygen species (ROS) defense, important to cope with ROS generated under hyperbaric oxygen partial pressures. Focusing on swimbladder tissue metabolism, levels of several mRNA species encoding glucose transport proteins were several-fold higher in silver eels, while enzymes of the glycolytic pathway were not affected. The significantly higher steady state level of a transcript encoding for membrane bound carbonic anhydrase, however, suggested that CO2 production in the pentose phosphate shunt and diffusion of CO2 was of particular importance in silver eel swimbladder. In addition, the mRNA level of a large number of genes related to immune response and to sexual maturation was significantly modified in the silver eel swimbladder. The modification of several processes related to protein metabolism and transport, cell cycle, and apoptosis suggested that these changes in swimbladder metabolism and permeability were achieved by increasing cell turn-over. The impact of an infection of the swimbladder with the nematode Anguillicola crassus has been assessed by comparing these expression changes with expression changes observed between uninfected yellow eel swimbladder tissue and infected silver eel swimbladder tissue. In contrast to uninfected silver eel swimbladder tissue, in infected tissue the mRNA level of several glycolytic enzymes was significantly elevated, and with respect to extracellular matrix, several mucin genes were many-fold higher in their mRNA level. Modification of many immune related genes and of the functional categories “response to

  20. Are dioxin-like contaminants responsible for the eel ( Anguilla anguilla) drama?

    NASA Astrophysics Data System (ADS)

    Palstra, A. P.; van Ginneken, V. J. T.; Murk, A. J.; van den Thillart, G. E. E. J. M.

    2006-03-01

    Eel populations worldwide are dangerously close to collapsing. Our study is the first to show that current levels of dioxin-like contaminants are strong candidates because of their devastating effects on development and survival of eel embryos. Female and male silver eels were artificially stimulated to maturation and reproduction by treatment with carp pituitary extracts and hCG, respectively. During maturation of female European silver eels, about 60 g fat per kg eel is incorporated in the oocytes. Together with the fat, however, persistent organic pollutants such as dioxin-like polychlorinated biphenyls (PCBs) are incorporated too. The total dioxin-like toxic potency of the individual gonad batches was determined as 2,3,7,8-tetrachlorodibenzo- p-dioxine equivalents (TEQs), using an in vitro reporter gene assay. The observed differences in development and survival showed a significant negative correlation with the TEQ levels in the gonads, already at levels far below the maximal allowable level for fish consumption, i.e., 4 ng TEQ/kg fish. The clear inverse relationship between the TEQ level and the survival period of the fertilised eggs strongly suggests that the current levels of dioxin-like compounds seriously impair the reproduction of the European eel. The peak of the environmental levels of dioxin-like PCBs and the decline of eel coincide worldwide, further suggesting that, in addition to other threats, these contaminants contributed significantly to the current collapse in eel populations.

  1. Prevalence of Anguillicoloides crassus and growth variation in migrant yellow-phase American eels of the upper Potomac River drainage.

    PubMed

    Zimmerman, Jennifer L; Welsh, Stuart A

    2012-11-01

    Prevalence of the non-native swim bladder nematode Anguillicoloides crassus has recently increased in American eels from estuaries of the North American Atlantic coast, but little is known about parasite prevalence or conditions of previous infection in upstream migrant eels within upper watersheds. This study is the first to confirm presence of A. crassus in the upper Potomac River watershed. We estimated A. crassus prevalence during 3 time periods: September to October 2006 (5/143 eels, 3.5%), August to October 2007 (0/49 eels), and June 2008 (0/50 eels). All eels were sampled from the Millville Dam eel ladder on the lower Shenandoah River, a Potomac River tributary located approximately 285 km upstream of Chesapeake Bay, USA. Of the 5 infected eels, parasite intensity was 1 for each eel, and mean intensity was also 1.0. A swim bladder degenerative index (SDI) was calculated for the 50 eels from the final sampling period, and 38% of those eels (19 of 50) showed signs of previous infection by A. crassus. We also aged 42 of the 50 eels (mean ± SE = 6.7 ± 0.29 yr, range 4 to 11 yr) from the final sampling period. Based on the range of possible SDI scores (0 to 6), severity of previously infected swim bladders was moderate (SDI = 1 or 2). Previously infected eels, however, had a lower length-at-age than that of uninfected eels. Female yellow-phase eels in upper watersheds develop into large highly fecund silver-phase adults; hence, a parasite-induced effect on growth of yellow-phase eels could ultimately reduce reproductive potential. PMID:23135140

  2. First evidence of European eels exiting the Mediterranean Sea during their spawning migration.

    PubMed

    Amilhat, Elsa; Aarestrup, Kim; Faliex, Elisabeth; Simon, Gaël; Westerberg, Håkan; Righton, David

    2016-01-01

    The migration route and the spawning site of the European eel Anguilla anguilla are still uncertain. It has been suggested that the Mediterranean eel stock does not contribute to spawning because there is no evidence of eels leaving the Mediterranean Sea. To test this hypothesis, we equipped eight female silver eels from the south of France with pop-up satellite tags during escapement from coastal waters. Once in deeper water, the eels quickly established diel vertical migration (DVM) between the upper and lower mesopelagic zone. Five tagged eels were taken by predators within the Mediterranean, but two eels reached the Atlantic Ocean after six months and at distances greater than 2000 km from release. These eels ceased their DVM while they negotiated the Gibraltar Strait, and remained in deep water until they reached the Atlantic Ocean, when they recommenced DVM. Our results are the first to show that eels from Mediterranean can cross the Strait of Gibraltar and continue their migration into the Atlantic Ocean. This finding suggests that Mediterranean countries, as for other EU states, have an important role to play in contributing to conservation efforts for the recovery of the European eel stock. PMID:26906289

  3. First evidence of European eels exiting the Mediterranean Sea during their spawning migration

    PubMed Central

    Amilhat, Elsa; Aarestrup, Kim; Faliex, Elisabeth; Simon, Gaël; Westerberg, Håkan; Righton, David

    2016-01-01

    The migration route and the spawning site of the European eel Anguilla anguilla are still uncertain. It has been suggested that the Mediterranean eel stock does not contribute to spawning because there is no evidence of eels leaving the Mediterranean Sea. To test this hypothesis, we equipped eight female silver eels from the south of France with pop-up satellite tags during escapement from coastal waters. Once in deeper water, the eels quickly established diel vertical migration (DVM) between the upper and lower mesopelagic zone. Five tagged eels were taken by predators within the Mediterranean, but two eels reached the Atlantic Ocean after six months and at distances greater than 2000 km from release. These eels ceased their DVM while they negotiated the Gibraltar Strait, and remained in deep water until they reached the Atlantic Ocean, when they recommenced DVM. Our results are the first to show that eels from Mediterranean can cross the Strait of Gibraltar and continue their migration into the Atlantic Ocean. This finding suggests that Mediterranean countries, as for other EU states, have an important role to play in contributing to conservation efforts for the recovery of the European eel stock. PMID:26906289

  4. Behavior and passage of silver-phase American eels, Anguilla rostrata (LeSueur), at a small hydroelectric facility

    USGS Publications Warehouse

    Haro, Alex; Castro-Santos, Ted; Boubée, Jacques

    2000-01-01

    Downstream migrant eels were monitored near a small (51 MW) hydroelectric facility on the Connecticut River (Massachusetts, USA) for two seasons using acoustic and radio telemetry. Eels frequently made several attempts over periods of one to several days to pass the station. Did activity of eels was variable, although most movements occurred at night. Eels occupied a variety of depths in the forebay area, but spent the greater proportion of time at or near the bottom (10 m), occasionally venturing to the surface. Horizontal movements usually spanned across the entire width of the forebay. There was no significant relationship between duration of forebay presence and either flow or light intensity. Although all telemetered eels passed via the turbines, some migrant eels did use a surface bypass.

  5. Plasmon modes of a silver thin film taper probed with STEM-EELS.

    PubMed

    Schmidt, Franz-Philipp; Ditlbacher, Harald; Trügler, Andreas; Hohenester, Ulrich; Hohenau, Andreas; Hofer, Ferdinand; Krenn, Joachim R

    2015-12-01

    By focusing propagating surface plasmons, electromagnetic energy can be delivered to nanoscale volumes. In this context, we employ electron energy loss spectroscopy in a scanning transmission electron microscope to characterize the full plasmonic mode spectrum of a silver thin film tapered to a sharp tip. We show that the plasmon modes can be ordered in film and edge modes and corroborate our assignment through supplementary numerical simulations. In particular, we find that the focused plasmon field at the taper tip is fueled by edge modes. PMID:26625078

  6. Interactive effects of dietary composition and hormonal treatment on reproductive development of cultured female European eel, Anguilla anguilla.

    PubMed

    da Silva, Filipa F G; Støttrup, Josianne G; Kjørsvik, Elin; Tveiten, Helge; Tomkiewicz, Jonna

    2016-08-01

    Farmed female eels were fed two experimental diets with similar proximate composition but different n-3 polyunsaturated fatty acid (PUFA) levels. Both diets had similar levels of arachidonic acid (ARA), while levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in one diet were approximately 4.5 and 2.6 times higher compared to the other diet, respectively. After the feeding period, each diet group was divided into two and each half received one of two hormonal treatments using salmon pituitary extract (SPE) for 13 weeks: i) a constant hormone dose of 18.75mg SPE/kg initial body weight (BW) and ii) a variable hormone dosage that increased from 12.5mg SPE/kg initial BW to 25mg SPE/kg initial BW. Results showed a significant interaction between diets and hormonal treatments on gonadosomatic index (GSI), indicating that the effect of broodstock diets on ovarian development depends on both nutritional status and hormonal regime. Females fed with higher levels of n-3 series PUFAs and stimulated with the constant hormonal treatment reached higher GSIs than those receiving the variable hormonal treatment. However, when females were fed lower levels of n-3 series PUFAs there was no difference in the effect of hormonal treatments on GSI. We also found that, independent of hormonal treatment, the diet with higher levels of n-3 series PUFAs led to the most advanced stages of oocyte development, such as germinal vesicle migration. Concentration of sex steroids (E2, T, and 11-KT) in the plasma did not differ between diets and hormonal treatments, but was significantly correlated with ovarian developmental stage. In conclusion, increasing dietary levels of n-3 PUFAs seemed to promote oocyte growth, leading to a more rapid progression of ovarian development in European eel subjected to hormonal treatment. PMID:27264530

  7. Are Biometric Parameters Helpful to Assess the Health Risk of Consuming Organochlorine Compounds Contaminated Silver European Eel (Anguilla anguilla)?

    PubMed

    Ferrante, Maria C; Fusco, Giovanna; Naccari, Clara; Meli, Rosaria; Clausi, Maria T

    2016-04-01

    Several organochlorine compounds (OCs) were measured in European eels from the Tevere river (Italy). It followed that some of them are still important chemical contaminants. Concentrations of dichlorodiphenyltrichloroethanes (DDTs) are hazardous for the consumer health; those of the 6 indicator polychlorinated biphenyls (PCBs) are often close to the current European maximum residue limit and always higher than the former limit. The relationship between OC concentrations, biometric parameters and the lipid content was then investigated. A strong positive correlation with eel size emerged for the indicator PCBs and DDTs concentrations expressed on wet weight basis. This is explained by the corresponding higher lipid percentage that characterizes bigger eels and the absence of a dilution effect for compounds of main concerns. On the basis of the PCB-TDI threshold for a 70 kg person, we suggest that 1 should consume no more than 2 eels per week each weighing about 100 g. Thus, we conclude that eel consumption should be limited and restricted to eels relatively shorter and lighter. PMID:26953718

  8. An Ultrastructural and Immunohistochemical Analysis of the Outer Plexiform Layer of the Retina of the European Silver Eel (Anguilla anguilla L).

    PubMed

    Klooster, Jan; Kamermans, Maarten

    2016-01-01

    Here we studied the ultrastructural organization of the outer retina of the European silver eel, a highly valued commercial fish species. The retina of the European eel has an organization very similar to most vertebrates. It contains both rod and cone photoreceptors. Rods are abundantly present and immunoreactive for rhodopsin. Cones are sparsely present and only show immunoreactivity for M-opsin and not for L-, S- or UV-cone opsins. As in all other vertebrate retinas, Müller cells span the width of the retina. OFF-bipolar cells express the ionotropic glutamate receptor GluR4 and ON-bipolar cells, as identified by their PKCα immunoreactivity, express the metabotropic receptor mGluR6. Both the ON- and the OFF-bipolar cell dendrites innervate the cone pedicle and rod spherule. Horizontal cells are surrounded by punctate Cx53.8 immunoreactivity indicating that the horizontal cells are strongly electrically coupled by gap-junctions. Connexin-hemichannels were found at the tips of the horizontal cell dendrites invaginating the photoreceptor synapse. Such hemichannels are implicated in the feedback pathway from horizontal cells to cones. Finally, horizontal cells are surrounded by tyrosine hydroxylase immunoreactivity, illustrating a strong dopaminergic input from interplexiform cells. PMID:27032102

  9. An Ultrastructural and Immunohistochemical Analysis of the Outer Plexiform Layer of the Retina of the European Silver Eel (Anguilla anguilla L)

    PubMed Central

    Klooster, Jan; Kamermans, Maarten

    2016-01-01

    Here we studied the ultrastructural organization of the outer retina of the European silver eel, a highly valued commercial fish species. The retina of the European eel has an organization very similar to most vertebrates. It contains both rod and cone photoreceptors. Rods are abundantly present and immunoreactive for rhodopsin. Cones are sparsely present and only show immunoreactivity for M-opsin and not for L-, S- or UV-cone opsins. As in all other vertebrate retinas, Müller cells span the width of the retina. OFF-bipolar cells express the ionotropic glutamate receptor GluR4 and ON-bipolar cells, as identified by their PKCα immunoreactivity, express the metabotropic receptor mGluR6. Both the ON- and the OFF-bipolar cell dendrites innervate the cone pedicle and rod spherule. Horizontal cells are surrounded by punctate Cx53.8 immunoreactivity indicating that the horizontal cells are strongly electrically coupled by gap-junctions. Connexin-hemichannels were found at the tips of the horizontal cell dendrites invaginating the photoreceptor synapse. Such hemichannels are implicated in the feedback pathway from horizontal cells to cones. Finally, horizontal cells are surrounded by tyrosine hydroxylase immunoreactivity, illustrating a strong dopaminergic input from interplexiform cells. PMID:27032102

  10. Male European eels are highly efficient long distance swimmers: effects of endurance swimming on maturation.

    PubMed

    Burgerhout, Erik; Brittijn, Sebastiaan A; Tudorache, Christian; de Wijze, Daniëlle L; Dirks, Ron P; van den Thillart, Guido E E J M

    2013-11-01

    European eels (Anguilla anguilla) migrate ~6000km towards their spawning area in the Sargasso Sea. Based on the recent discovery that males swim even more efficiently than females, it was predicted that males also would be able to swim ~6000km within six months. Additionally, eels do not mature naturally in captivity due to strong neural inhibition. Earlier, it was hypothesized that swimming exercise is a natural trigger to induce sexual maturation and may even result in full maturation. In the present study two groups of farmed male silver eels were subjected to either endurance swimming or resting for up to 6months. It was found that male eels were able to swim continuously for a total distance of 6670km within 6months. The body weight decrease in swimming and resting males after 6months was similar (<30g) underlining the extreme low energy cost of swimming. In contrast to our expectation long-term swimming did not induce sexual maturation in farmed silver eels, suggesting that swimming alone is not sufficient as a trigger for sexual maturation. In conclusion, male eels are efficient long distance swimmers and likely able to cover the distance to the Sargasso Sea within the expected time span of 6months. PMID:23962432

  11. The potential reproductive contribution of Mediterranean migrating eels to the Anguilla anguilla stock

    NASA Astrophysics Data System (ADS)

    Capoccioni, Fabrizio; Costa, Corrado; Canali, Emiliano; Aguzzi, Jacopo; Antonucci, Francesca; Ragonese, Sergio; Bianchini, Marco L.

    2014-11-01

    The European eel is a highly migratory fish. After the reproduction in the Sargasso Sea early larval-stages start a passive ocean migration towards European and Mediterranean continental waters. After several years as yellow eels, mature adults change to silver stage and then start their return trip. The trajectory of their backward migration is unknown, because of low probability of capturing migrating individuals, having this capture never been reported in the Mediterranean. Recently, 8 silver eels were collected in the Strait of Sicily. Using literature information about possible individual route and speed, their geographical position was projected up to the spawning site during reproductive season. Despite using optimal and continuous migration swimming speed, none of the specimens may have been able to reach the Sargasso Sea in time for mating. Subsequently, to identify putative Mediterranean areas from which eels could have been reaching the spawning grounds on time, a backward scenario was postulated using the previous scientific assumptions. Our results suggests that just a small quota of Mediterranean silver males successfully reaches the Sargasso area, and only females from the westernmost and central parts of the basin could be able to fruitfully pond their eggs during the supposed spawning period.

  12. The potential reproductive contribution of Mediterranean migrating eels to the Anguilla anguilla stock.

    PubMed

    Capoccioni, Fabrizio; Costa, Corrado; Canali, Emiliano; Aguzzi, Jacopo; Antonucci, Francesca; Ragonese, Sergio; Bianchini, Marco L

    2014-01-01

    The European eel is a highly migratory fish. After the reproduction in the Sargasso Sea early larval-stages start a passive ocean migration towards European and Mediterranean continental waters. After several years as yellow eels, mature adults change to silver stage and then start their return trip. The trajectory of their backward migration is unknown, because of low probability of capturing migrating individuals, having this capture never been reported in the Mediterranean. Recently, 8 silver eels were collected in the Strait of Sicily. Using literature information about possible individual route and speed, their geographical position was projected up to the spawning site during reproductive season. Despite using optimal and continuous migration swimming speed, none of the specimens may have been able to reach the Sargasso Sea in time for mating. Subsequently, to identify putative Mediterranean areas from which eels could have been reaching the spawning grounds on time, a backward scenario was postulated using the previous scientific assumptions. Our results suggests that just a small quota of Mediterranean silver males successfully reaches the Sargasso area, and only females from the westernmost and central parts of the basin could be able to fruitfully pond their eggs during the supposed spawning period. PMID:25424371

  13. The potential reproductive contribution of Mediterranean migrating eels to the Anguilla anguilla stock

    PubMed Central

    Capoccioni, Fabrizio; Costa, Corrado; Canali, Emiliano; Aguzzi, Jacopo; Antonucci, Francesca; Ragonese, Sergio; Bianchini, Marco L.

    2014-01-01

    The European eel is a highly migratory fish. After the reproduction in the Sargasso Sea early larval-stages start a passive ocean migration towards European and Mediterranean continental waters. After several years as yellow eels, mature adults change to silver stage and then start their return trip. The trajectory of their backward migration is unknown, because of low probability of capturing migrating individuals, having this capture never been reported in the Mediterranean. Recently, 8 silver eels were collected in the Strait of Sicily. Using literature information about possible individual route and speed, their geographical position was projected up to the spawning site during reproductive season. Despite using optimal and continuous migration swimming speed, none of the specimens may have been able to reach the Sargasso Sea in time for mating. Subsequently, to identify putative Mediterranean areas from which eels could have been reaching the spawning grounds on time, a backward scenario was postulated using the previous scientific assumptions. Our results suggests that just a small quota of Mediterranean silver males successfully reaches the Sargasso area, and only females from the westernmost and central parts of the basin could be able to fruitfully pond their eggs during the supposed spawning period. PMID:25424371

  14. Influence of site, season, silvering stage, and length on the parasites of the European eel Anguilla anguilla in two Mediterranean coastal lagoons of the island of Corsica, France using indicator species method.

    PubMed

    Filippi, Jean-José; Quilichini, Yann; Foata, Joséphine; Marchand, Bernard

    2013-08-01

    The parasites of 425 European eels, Anguilla anguilla, were studied between 2009 and 2012 in two Mediterranean coastal lagoons of the island of Corsica, France. An indicator value (IndVal) method was used for analysis, which combines measures of fidelity and specificity. Because of its resilience to detect changes in abundance, IndVal is an effective ecological bioindicator. The IndVal method demonstrated that site, season, silvering stage, and length could influence the occurrence of parasite species in European eel. A randomization test identified ten parasite species as having a significant indicator value for site (lagoons differed principally in salinity: oligohaline to polyhaline for the Biguglia lagoon and polyhaline to euhaline for the Urbino lagoon; the digeneans Bucephalus anguillae and Lecithochirium musculus, the cestodes Bothriocephalus claviceps, Proteocephalus macrocephalus, and larvae of Myzophyllobothrium sp., the nematodes Anguillicoloides crassus, and encysted larvae of Contracaecum sp., the acanthocephalan Acanthocephaloides incrassatus, the monogenean Pseudodactyogyrus anguillae, and the copepod Ergasilus gibbus); one parasite species for the spring season (the acanthocephalan A. incrassatus); six parasite species for silvering stage (yellow, pre-silver, silver; the trematodes B. anguillae and Deropristis inflata, encysted larvae of the nematode Contracaecum sp., the acanthocephalan A. incrassatus, the monogenean P. anguillae, and the copepod E. gibbus); and three parasite species for some of the five length classes (the cestode P. macrocephalus, encysted larvae of the nematode Contracaecum sp., and the monogenean P. anguillae). Data for species composition and infection levels should help to improve the management of parasitism in the populations of European eels. PMID:23739809

  15. Effects of high hydrostatic pressure on the pituitary-gonad axis in the European eel, Anguilla anguilla (L.).

    PubMed

    Sébert, Marie-Emilie; Amérand, Aline; Vettier, Aurélie; Weltzien, Finn-Arne; Pasqualini, Catherine; Sébert, Philippe; Dufour, Sylvie

    2007-01-01

    European silver eels are thought to undergo sexual maturation during their oceanic reproductive migration from the European continent to their spawning area in the Sargasso Sea. Tracking data and various anatomical and physiological features suggest that silver eels migrate in deep sea, leading us to hypothesise that high hydrostatic pressure (HP) influences the induction of eel reproduction. We subjected female and male silver eels to 101ATA for 3 and 7 weeks, respectively, in a hyperbaric chamber equipped with a freshwater recirculation system. In comparison with control eels kept at 1 ATA, HP effects were tested against the messenger RNA levels of pituitary gonadotropins (LHbeta, FSHbeta) using quantitative real-time RT-PCR. The effects of HP on gonadal activity were estimated by measuring gonadosomatic index, oocyte diameter and plasma levels of vitellogenin (Vtg) and sex steroids (E(2), 11-KT). At the pituitary level, LHbeta expression tended to increase while FSHbeta expression decreased in both sex, leading to an increase in the LHbeta/FSHbeta ratio. This suggests a differential effect of HP on the expression of the two gonadotropins. In females submitted to HP, we observed a significant increase in oocyte diameter and plasma levels of 11-KT and E(2). A similar trend was observed for 11-KT plasma levels in males. In females, Vtg plasma levels also significantly increased, reflecting the stimulatory effect of sex steroids on hepatic vitellogenesis. Our results suggest that HP plays a specific and positive role in eel reproduction but additional environmental and internal factors are necessary to ensure complete sexual maturation. PMID:17324430

  16. The First Record of Female Maturation of the Short-finned Eel, Anguilla bicolor bicolor, in the Coastal Waters of Thailand

    PubMed Central

    Tongnunui, Prasert; Yoknoi, Nuengruetai; Pechnoi, Pimwipa; Yamada, Hideaki; Kon, Koetsu

    2016-01-01

    The objective of the present study was to provide reproductive biological information on the gonadal development of the short-finned eel, Anguilla bicolor bicolor, which inhabits the coastal waters of Thailand. Short-finned eels were collected from three coastal areas of Trang Province, southern Thailand, from September 2011 to December 2013. The gonads of 151 specimens were subjected to a histological analysis. The histological observations found both immature and maturing females. Based on the advanced oocytes within an entire ovarian section, the ovaries of the studied specimens were classified into three maturity phases: 1) the immature phase was defined by ovaries that showed oogonia and primary growth oocytes, 2) the developing phase was defined by ovaries that contained early vitellogenic-stage oocytes with some oogonia present along with cortical alveolar oocytes and many adipocytes, and 3) the late vitellogenic phase refers to ovaries that contained nearly entirely late-vitellogenic oocytes. The density of oocytes in juxtaposition to an adipose matrix is considered to represent the degree of gonadal development. The results of this study may be applicable in further defining the general spawning area of A. bicolor bicolor in regions of the Indian Ocean. PMID:27019687

  17. The First Record of Female Maturation of the Short-finned Eel, Anguilla bicolor bicolor, in the Coastal Waters of Thailand.

    PubMed

    Tongnunui, Prasert; Yoknoi, Nuengruetai; Pechnoi, Pimwipa; Yamada, Hideaki; Kon, Koetsu

    2016-02-01

    The objective of the present study was to provide reproductive biological information on the gonadal development of the short-finned eel, Anguilla bicolor bicolor, which inhabits the coastal waters of Thailand. Short-finned eels were collected from three coastal areas of Trang Province, southern Thailand, from September 2011 to December 2013. The gonads of 151 specimens were subjected to a histological analysis. The histological observations found both immature and maturing females. Based on the advanced oocytes within an entire ovarian section, the ovaries of the studied specimens were classified into three maturity phases: 1) the immature phase was defined by ovaries that showed oogonia and primary growth oocytes, 2) the developing phase was defined by ovaries that contained early vitellogenic-stage oocytes with some oogonia present along with cortical alveolar oocytes and many adipocytes, and 3) the late vitellogenic phase refers to ovaries that contained nearly entirely late-vitellogenic oocytes. The density of oocytes in juxtaposition to an adipose matrix is considered to represent the degree of gonadal development. The results of this study may be applicable in further defining the general spawning area of A. bicolor bicolor in regions of the Indian Ocean. PMID:27019687

  18. Brominated flame retardants and dechloranes in eels from German Rivers.

    PubMed

    Sühring, Roxana; Möller, Axel; Freese, Marko; Pohlmann, Jan-Dag; Wolschke, Hendrik; Sturm, Renate; Xie, Zhiyong; Hanel, Reinhold; Ebinghaus, Ralf

    2013-01-01

    The levels of PBDEs, alternate BFRs and dechloranes in European Eel (Anguilla anguilla) samples (elvers, yellow and silver eels) were investigated to compare the contamination of eels from the rivers Elbe and Rhine and to estimate the BFR contamination throughout the eel's life cycle. PBDEs were the dominating flame retardants (FRs) in muscle tissues of yellow and silver eels, while the alternate BFR 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) and the Dechlorane 602 were the dominating FRs in elvers (juvenile eels). Concentrations of FRs in silver eels from river Rhine were generally higher than concentrations in other eels analysed with up to 46 ng g(-1) wet weight (ww) ∑PBDEs. The concentrations in yellow and silver eels from river Elbe were similar with an average of 9.0±5.1 ng g(-1)ww and 8.1±3.7 ng g(-1)ww respectively. PBDE concentrations in elvers were comparably low (0.02 (BDE-100) to 0.1 (BDE-183) ng g(-1)ww), which lead to the conclusion that these contaminants were mostly ingested within the rivers. Among the alternate BFRs and dechloranes, DPTE as well as the Dechlorane 602 and Dechlorane Plus (DP) were found in all life cycle stages and rivers with concentrations between 0.01 ng g(-1)ww and 0.7 ng g(-1)ww. Dechlorane 603 could only be detected in silver eels from river Rhine. Pentabromoethylbenzene (PBEB) was only found in yellow and silver eels and bis(2-ethylhexyl)tetrabromophthalate (BEHTBP) could only be detected in elvers. These are the first reports of Dec-602 and 603 in aquatic organisms from Europe. The results of this study show the lasting relevance of PBDEs as contaminants in rivers and river-dwelling species but also the growing relevance of emerging contaminants such as alternate BFRs and dechloranes. PMID:22985592

  19. Oceanic migration and spawning of anguillid eels.

    PubMed

    Tsukamoto, K

    2009-06-01

    Many aspects of the life histories of anguillid eels have been revealed in recent decades, but the spawning migrations of their silver eels in the open ocean still remains poorly understood. This paper overviews what is known about the migration and spawning of anguillid species in the ocean. The factors that determine exactly when anguillid eels will begin their migrations are not known, although environmental influences such as lunar cycle, rainfall and river discharge seem to affect their patterns of movement as they migrate towards the ocean. Once in the ocean on their way to the spawning area, silver eels probably migrate in the upper few hundred metres, while reproductive maturation continues. Although involvement of a magnetic sense or olfactory cues seems probable, how they navigate or what routes they take are still a matter of speculation. There are few landmarks in the open ocean to define their spawning areas, other than oceanographic or geological features such as oceanic fronts or seamounts in some cases. Spawning of silver eels in the ocean has never been observed, but artificially matured eels of several species have exhibited similar spawning behaviours in the laboratory. Recent collections of mature adults and newly spawned preleptocephali in the spawning area of the Japanese eel Anguilla japonica have shown that spawning occurs during new moon periods in the North Equatorial Current region near the West Mariana Ridge. These data, however, show that the latitude of the spawning events can change among months and years depending on oceanographic conditions. Changes in spawning location of this and other anguillid species may affect their larval transport and survival, and appear to have the potential to influence recruitment success. A greater understanding of the spawning migration and the choice of spawning locations by silver eels is needed to help conserve declining anguillid species. PMID:20735675

  20. Effect of exercise training on respiration and reactive oxygen species metabolism in eel red muscle.

    PubMed

    Mortelette, Hélène; Amérand, Aline; Sébert, Philippe; Belhomme, Marc; Calvès, Patrick; Moisan, Christine

    2010-07-31

    This paper deals with the effects of exercise training on oxygen consumption (MO(2)) and ROS metabolism in the red muscle of trained and untrained female silver eels. Their critical swimming speed (U(crit)) was determined before and after a 4-day training (10h of swimming at 70% of U(crit) and 14 h at 50%, every day). The U(crit) of trained eels increased significantly (by about 7%). The in vitro MO(2) and ROS production by the red fibres were higher (not significant) in trained than in untrained eels, but the ROS production/MO(2) ratio was alike in both groups. The antioxidant-enzyme activities and lipoperoxidation index in trained eels were both lower than those of the untrained ones. These biochemical changes related to the increase in U(crit) suggest that such a training session could maintained or even increased aerobic power of the red muscle without deleterious impact by ROS. These regulations could play a role in the eel's swimming performance efficiency. PMID:20566309

  1. Differences in organotin accumulation among ecological migratory types of the Japanese eel Anguilla japonica

    NASA Astrophysics Data System (ADS)

    Ohji, Madoka; Harino, Hiroya; Arai, Takaomi

    2006-08-01

    In order to examine the ecological risks caused by organotin compounds (OTs) in diadromous fish migrating between sea and freshwater, tributyltin (TBT) and triphenyltin (TPT) compounds, and their breakdown products, were determined in the catadromous eel Anguilla japonica having sea, estuarine and river life histories, collected in Japanese sea, brackish and fresh waters. Ontogenic changes in otolith strontium (Sr) and calcium (Ca) concentrations were examined along life history transect to discriminate the migration type. There were generally three different patterns, which were categorized 'sea eels' (spent most of their life in the sea and did not enter freshwater), 'estuarine eels' (inhabited estuaries or switched between different habitats), and 'river eels' (entered and remained in freshwater river habitats after arrival in the estuary) according to the otolith Sr:Ca ratio. There were generally no significant correlations between TBT and TPT accumulation and various biological characteristics such as total length (TL), body weight (BW), age and sex in A. japonica. The concentrations of TBT and TPT in silver eels (mature eels) were significantly higher than those in yellow eels (immature eels), and the percentages of TBT and TPT were also higher in silver eels than in yellow eels. A positive correlation was found between TBT concentration and the gonad-somatic index (GSI). It is thus considered that silver eels have a higher risk of contamination by TBT than yellow eels. TBT and TPT concentrations in sea eels were significantly higher than those in river eels. In contrast, no significant differences were observed in TBT and TPT concentrations in estuarine eels compared to sea and river eels. These results suggest that sea eels have a higher ecological risk of OT contamination than river eels during their life history, and the risk of OTs in estuarine eels is considered to be intermediate between that of sea and river eels. Positive linear relationships were

  2. Dam removal increases American eel abundance in distant headwater streams

    USGS Publications Warehouse

    Hitt, Nathaniel P.; Eyler, Sheila; Wofford, John E.B.

    2012-01-01

    American eel Anguilla rostrata abundances have undergone significant declines over the last 50 years, and migration barriers have been recognized as a contributing cause. We evaluated eel abundances in headwater streams of Shenandoah National Park, Virginia, to compare sites before and after the removal of a large downstream dam in 2004 (Embrey Dam, Rappahannock River). Eel abundances in headwater streams increased significantly after the removal of Embrey Dam. Observed eel abundances after dam removal exceeded predictions derived from autoregressive models parameterized with data prior to dam removal. Mann–Kendall analyses also revealed consistent increases in eel abundances from 2004 to 2010 but inconsistent temporal trends before dam removal. Increasing eel numbers could not be attributed to changes in local physical habitat (i.e., mean stream depth or substrate size) or regional population dynamics (i.e., abundances in Maryland streams or Virginia estuaries). Dam removal was associated with decreasing minimum eel lengths in headwater streams, suggesting that the dam previously impeded migration of many small-bodied individuals (<300 mm TL). We hypothesize that restoring connectivity to headwater streams could increase eel population growth rates by increasing female eel numbers and fecundity. This study demonstrated that dams may influence eel abundances in headwater streams up to 150 river kilometers distant, and that dam removal may provide benefits for eel management and conservation at the landscape scale.

  3. Induced oogenesis of the European eel (Anguilla anguilla L.) in freshwater condition.

    PubMed

    Horváth, L; Székely, Cs; Boczonádi, Zs; Mészáros, E; Bercsényi, M; Urbányi, B; Müller, T

    2011-12-01

    European eel is a catadromous fish species, which means that after living in freshwater premature individuals adapt to sea water, and migrate to the Sargasso Sea for spawning. Although male eel can be sexually matured even in freshwater, to date, it was believed that female eel can be matured only in seawater. Here we show that the process of sexual maturation may be induced in freshwater by treating female eels with carp pituitary (GSI = 9.87 ± 1.55%). It is thus proposed that seawater condition is not an obligatory environment for stimulating gametogenesis and for artificial maturation of the European eel in neither gender. PMID:22119876

  4. Light-Sensitive Vertical Migration of the Japanese Eel Anguilla japonica Revealed by Real-Time Tracking and Its Utilization for Geolocation

    PubMed Central

    Chow, Seinen; Okazaki, Makoto; Watanabe, Tomowo; Segawa, Kyohei; Yamamoto, Toshihiro; Kurogi, Hiroaki; Tanaka, Hideki; Ai, Ken-ichiro; Kawai, Miho; Yamamoto, Shin-ichi; Mochioka, Noritaka; Manabe, Ryotaro; Miyake, Yoichi

    2015-01-01

    Short-time tracking (one to eight days) of the Japanese eel (Anguilla japonica) using ultrasonic transmitter was performed in the tropical-subtropical area adjacent to the spawning area and temperate area off the Japanese Archipelago. Of 16 eels (11 wild and five farmed) used, 10 wild eels displayed clear diel vertical migration (DVM) from the beginning, while the other five farmed eels tracked for 19 to 66 hours did not. During daytime, a significantly positive correlation between migration depth and light intensity recorded on the vessel was observed in the 10 wild eels, indicating that the eels were sensitive to sunlight even at the middle to lower mesopelagic zone (500 to 800 m). During nighttime, the eel migration depth was observed to be associated with the phase, rising and setting of the moon, indicating that the eels were sensitive to moonlight at the upper mesopelagic zone (<300 m). Two of 10 wild eels were in the yellow stage but shared similar DVM with the silver stage eels. Swimbladders of three silver stage eels were punctured before releasing, but very little effect on DVM was observed. The eels very punctually initiated descent upon nautical dawn and ascent upon sunset, enabling us to determine local times for sunrise and sunset, and hence this behavior may be used for geolocating eels. In fact, estimated positions of eels based on the depth trajectory data were comparable or even better than those obtained by light-based archival tag in other fish species. PMID:25875179

  5. Migratory Restlessness and the Role of Androgen for Increasing Behavioral Drive in the Spawning Migration of the Japanese eel

    PubMed Central

    Sudo, Ryusuke; Tsukamoto, Katsumi

    2015-01-01

    Migratory restlessness refers to a type of locomotor activity observed just before the onset of a migration. This behavior is primarily known in birds, where it is considered to be an indicator of the urge for migration. In contrast, little is known about migratory restlessness in fishes. To confirm migratory restlessness in a fish, we measured the locomotor activity of the Japanese eel, Anguilla japonica during its migration season. Migratory-phase silver eels showed higher locomotor activity in aquaria than yellow eels at the non-migratiory growth-phase. Silver eels stayed outside of their shelters for longer durations in dark periods than yellow eels and were active even in light periods when yellow eels were inactive in the shelters. Silver eels had higher levels of the androgen hormone 11-ketotestosterone at the end of experiment than yellow eels. Administration of 11-ketotesosterone to yellow eels induced higher levels of locomotor activity than that observed in non-treated controls. These findings suggest that anguillid eels exhibit migratory restlessness just before their spawning migration and that 11-ketotestosterone may be involved in the onset of this behavior. PMID:26617079

  6. Silver

    Integrated Risk Information System (IRIS)

    Silver ; CASRN 7440 - 22 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects )

  7. Thyroid endocrine status of wild European eels (Anguilla anguilla) in the Loire (France). Relationships with organic contaminant body burdens.

    PubMed

    Couderc, M; Marchand, J; Zalouk-Vergnoux, A; Kamari, A; Moreau, B; Blanchet-Letrouvé, I; Le Bizec, B; Mouneyrac, C; Poirier, L

    2016-04-15

    In teleost fish, thyroid function is involved in various critical physiological processes. Given the complexity of the hypothalamo-pituitary-thyroid (HPT) axis, a large number of genes and proteins can be the potential target of endocrine-disrupting compounds (EDCs). The aim of this study was to evaluate, in yellow and silver European eels (Anguilla anguilla), potential effects of EDCs on thyroid status by analyzing the associations between EDC body burdens and thyroid hormones (THs). In yellow individuals, greater free T3/T4 ratios (FT3/FT4) and lower plasma FT4 levels were associated with greater concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), as highlighted by significant correlations with many congeners. Few positive relationships with alkylphenols were noticed. In contrast, silver eels usually exhibited less significant correlations between THs and contaminant loads. Expression of a series of genes involved in the HPT axis was also investigated in the silver individuals. Concerning mRNA expression in silver females, some main correlations were noticed: thyroid-stimulating hormone (TSHβ) gene expression was significantly correlated to numerous PCBs, and hepatic mRNA levels of deiodinase 2 (Deio 2) were negatively correlated to 2-hydroxyfluorene (2-OHF) and 2-naphtol (2-OHNa). Thyroid receptor (TRα and TRβ) mRNA levels exhibited weak negative correlations with some PBDEs in silver females and males. Hepatic vitellogenin (Vtg) mRNA levels were detected in all silver males but at lower levels than in silver females. In males, Vtg mRNA levels were positively associated to FT4/TT4. In silver females, strong positive correlations were found between congeners of PCBs, PBDEs and PFAS suggesting potential estrogenic effects. Overall, the observed results indicate that several organic contaminants, mainly dl-, ndl-PCBs and PBDEs, could be associated with changes in thyroid homeostasis in these fish, via direct or indirect

  8. Shark predation on migrating adult American eels (Anguilla rostrata) in the Gulf of St. Lawrence.

    PubMed

    Béguer-Pon, Mélanie; Benchetrit, José; Castonguay, Martin; Aarestrup, Kim; Campana, Steven E; Stokesbury, Michael J W; Dodson, Julian J

    2012-01-01

    In an attempt to document the migratory pathways and the environmental conditions encountered by American eels during their oceanic migration to the Sargasso Sea, we tagged eight silver eels with miniature satellite pop-up tags during their migration from the St. Lawrence River in Québec, Canada. Surprisingly, of the seven tags that successfully transmitted archived data, six were ingested by warm-gutted predators, as observed by a sudden increase in water temperature. Gut temperatures were in the range of 20 to 25°C-too cold for marine mammals but within the range of endothermic fish. In order to identify the eel predators, we compared their vertical migratory behavior with those of satellite-tagged porbeagle shark and bluefin tuna, the only endothermic fishes occurring non-marginally in the Gulf of St. Lawrence. We accurately distinguished between tuna and shark by using the behavioral criteria generated by comparing the diving behavior of these two species with those of our unknown predators. Depth profile characteristics of most eel predators more closely resembled those of sharks than those of tuna. During the first days following tagging, all eels remained in surface waters and did not exhibit diel vertical migrations. Three eels were eaten at this time. Two eels exhibited inverse diel vertical migrations (at surface during the day) during several days prior to predation. Four eels were eaten during daytime, whereas the two night-predation events occurred at full moon. Although tagging itself may contribute to increasing the eel's susceptibility to predation, we discuss evidence suggesting that predation of silver-stage American eels by porbeagle sharks may represent a significant source of mortality inside the Gulf of St. Lawrence and raises the possibility that eels may represent a reliable, predictable food resource for porbeagle sharks. PMID:23082131

  9. Shark Predation on Migrating Adult American Eels (Anguilla rostrata) in the Gulf of St. Lawrence

    PubMed Central

    Béguer-Pon, Mélanie; Benchetrit, José; Castonguay, Martin; Aarestrup, Kim; Campana, Steven E.; Stokesbury, Michael J. W.; Dodson, Julian J.

    2012-01-01

    In an attempt to document the migratory pathways and the environmental conditions encountered by American eels during their oceanic migration to the Sargasso Sea, we tagged eight silver eels with miniature satellite pop-up tags during their migration from the St. Lawrence River in Québec, Canada. Surprisingly, of the seven tags that successfully transmitted archived data, six were ingested by warm-gutted predators, as observed by a sudden increase in water temperature. Gut temperatures were in the range of 20 to 25°C—too cold for marine mammals but within the range of endothermic fish. In order to identify the eel predators, we compared their vertical migratory behavior with those of satellite-tagged porbeagle shark and bluefin tuna, the only endothermic fishes occurring non-marginally in the Gulf of St. Lawrence. We accurately distinguished between tuna and shark by using the behavioral criteria generated by comparing the diving behavior of these two species with those of our unknown predators. Depth profile characteristics of most eel predators more closely resembled those of sharks than those of tuna. During the first days following tagging, all eels remained in surface waters and did not exhibit diel vertical migrations. Three eels were eaten at this time. Two eels exhibited inverse diel vertical migrations (at surface during the day) during several days prior to predation. Four eels were eaten during daytime, whereas the two night-predation events occurred at full moon. Although tagging itself may contribute to increasing the eel's susceptibility to predation, we discuss evidence suggesting that predation of silver-stage American eels by porbeagle sharks may represent a significant source of mortality inside the Gulf of St. Lawrence and raises the possibility that eels may represent a reliable, predictable food resource for porbeagle sharks. PMID:23082131

  10. Too short to spawn? Implications of small body size and swimming distance on successful migration and maturation of the European eel Anguilla anguilla.

    PubMed

    Clevestam, P D; Ogonowski, M; Sjöberg, N B; Wickström, H

    2011-04-01

    Individual net fat reserves after migration and reproductive investments were calculated for migrating female silver eels Anguilla anguilla (n = 387) collected in the outlet region of the Baltic Sea during the autumn run. It is estimated that 20·4% of the A. anguilla had completely exhausted all initial fat reserves and that 45·0% of A. anguilla were within 90% of complete energy depletion after migration and reproduction. This study concludes that a combination of body size and distance (6900 km) to the spawning area in the Sargasso Sea explains the results. An increase in the costs of migration due to heavy infection with Anguillicoloides crassus was also evaluated in an additional scenario with results showing that 26·4% of the A. anguilla had completely depleted all fat reserves. It is hypothesized that a large proportion of female silver A. anguilla from the Baltic Sea catchment area will have inadequate or suboptimal reserves for successful migration and reproduction. PMID:21463308

  11. Edward Bancroft's "Torporific Eels".

    PubMed

    Finger, Stanley

    2009-01-01

    Edward Bancroft was a medical apprentice in Connecticut before running off to Guiana in 1763. While in South America, he practiced medicine and collected material for a lengthy book on the region, which he published after he settled in London. Bancroft's Essay (1769) contains a description of the "torporific eels" found in the warm rivers of Guiana, along with a series of experiments suggesting that the eel's powers are electrical. It also calls for studies to determine whether saltwater torpedo rays might demonstrate the same properties, which Bancroft expected would be the case. Today, Bancroft is best remembered for serving Benjamin Franklin and the American delegation in France during the War of Independence, and for being a double agent. But what this colorful man wrote about the South American eels helped to make an early case for animal electricity and stimulated Franklin to encourage John Walsh to conduct his landmark electrical experiments on torpedoes and electric eels in the 1770s. These efforts led to new way of thinking about the physiology of the nervous and muscular systems, even in nonspecialized fish. PMID:19168945

  12. Oceanic spawning ecology of freshwater eels in the western North Pacific

    PubMed Central

    Tsukamoto, Katsumi; Chow, Seinen; Otake, Tsuguo; Kurogi, Hiroaki; Mochioka, Noritaka; Miller, Michael J.; Aoyama, Jun; Kimura, Shingo; Watanabe, Shun; Yoshinaga, Tatsuki; Shinoda, Akira; Kuroki, Mari; Oya, Machiko; Watanabe, Tomowo; Hata, Kazuhiro; Ijiri, Shigeho; Kazeto, Yukinori; Nomura, Kazuharu; Tanaka, Hideki

    2011-01-01

    The natural reproductive ecology of freshwater eels remained a mystery even after some of their offshore spawning areas were discovered approximately 100 years ago. In this study, we investigate the spawning ecology of freshwater eels for the first time using collections of eggs, larvae and spawning-condition adults of two species in their shared spawning area in the Pacific. Ovaries of female Japanese eel and giant mottled eel adults were polycyclic, suggesting that freshwater eels can spawn more than once during a spawning season. The first collection of Japanese eel eggs near the West Mariana Ridge where adults and newly hatched larvae were also caught shows that spawning occurs during new moon periods throughout the spawning season. The depths where adults and newly hatched larvae were captured indicate that spawning occurs in shallower layers of 150–200 m and not at great depths. This type of spawning may reduce predation and facilitate reproductive success. PMID:21285957

  13. Low larval abundance in the Sargasso Sea: new evidence about reduced recruitment of the Atlantic eels.

    PubMed

    Hanel, Reinhold; Stepputtis, Daniel; Bonhommeau, Sylvain; Castonguay, Martin; Schaber, Matthias; Wysujack, Klaus; Vobach, Michael; Miller, Michael J

    2014-12-01

    The European eel Anguilla anguilla has shown decreased recruitment in recent decades. Despite increasing efforts to establish species recovery measures, it is unclear if the decline was caused by reduced numbers of reproductive-stage silver eels reaching the spawning area, low early larval survival, or increased larval mortality during migration to recruitment areas. To determine if larval abundances in the spawning area significantly changed over the past three decades, a plankton trawl sampling survey for anguillid leptocephali was conducted in March and April 2011 in the spawning area of the European eel that was designed to directly compare to collections made in the same way in 1983 and 1985. The catch rates of most anguilliform leptocephali were lower in 2011, possibly because of the slightly smaller plankton trawl used, but the relative abundances of European eel and American eel, Anguilla rostrata, leptocephali were much lower in 2011 than in 1983 and 1985 when compared to catches of other common leptocephali. The leptocephali assemblage was the same in 2011 as in previous years, but small larvae of mesopelagic snipe eels, Nemichthys scolopaceus, which spawn sympatrically with anguillid eels, were less abundant. Temperature fronts in the spawning area were also poorly defined compared to previous years. Although the causes for low anguillid larval abundances in 2011 are unclear, the fact that there are presently fewer European and American eel larvae in the spawning area than during previous time periods indicates that decreased larval abundance and lower eventual recruitment begin within the spawning area. PMID:25307845

  14. Low larval abundance in the Sargasso Sea: new evidence about reduced recruitment of the Atlantic eels

    NASA Astrophysics Data System (ADS)

    Hanel, Reinhold; Stepputtis, Daniel; Bonhommeau, Sylvain; Castonguay, Martin; Schaber, Matthias; Wysujack, Klaus; Vobach, Michael; Miller, Michael J.

    2014-12-01

    The European eel Anguilla anguilla has shown decreased recruitment in recent decades. Despite increasing efforts to establish species recovery measures, it is unclear if the decline was caused by reduced numbers of reproductive-stage silver eels reaching the spawning area, low early larval survival, or increased larval mortality during migration to recruitment areas. To determine if larval abundances in the spawning area significantly changed over the past three decades, a plankton trawl sampling survey for anguillid leptocephali was conducted in March and April 2011 in the spawning area of the European eel that was designed to directly compare to collections made in the same way in 1983 and 1985. The catch rates of most anguilliform leptocephali were lower in 2011, possibly because of the slightly smaller plankton trawl used, but the relative abundances of European eel and American eel, Anguilla rostrata, leptocephali were much lower in 2011 than in 1983 and 1985 when compared to catches of other common leptocephali. The leptocephali assemblage was the same in 2011 as in previous years, but small larvae of mesopelagic snipe eels, Nemichthys scolopaceus, which spawn sympatrically with anguillid eels, were less abundant. Temperature fronts in the spawning area were also poorly defined compared to previous years. Although the causes for low anguillid larval abundances in 2011 are unclear, the fact that there are presently fewer European and American eel larvae in the spawning area than during previous time periods indicates that decreased larval abundance and lower eventual recruitment begin within the spawning area.

  15. Assessing patterns of hybridization between North Atlantic eels using diagnostic single-nucleotide polymorphisms.

    PubMed

    Pujolar, J M; Jacobsen, M W; Als, T D; Frydenberg, J; Magnussen, E; Jónsson, B; Jiang, X; Cheng, L; Bekkevold, D; Maes, G E; Bernatchez, L; Hansen, M M

    2014-06-01

    The two North Atlantic eel species, the European eel (Anguilla anguilla) and the American eel (Anguilla rostrata), spawn in partial sympatry in the Sargasso Sea, providing ample opportunity to interbreed. In this study, we used a RAD (Restriction site Associated DNA) sequencing approach to identify species-specific diagnostic single-nucleotide polymorphisms (SNPs) and design a low-density array that combined with screening of a diagnostic mitochondrial DNA marker. Eels from Iceland (N=159) and from the neighboring Faroe Islands (N=29) were genotyped, along with 94 larvae (49 European and 45 American eel) collected in the Sargasso Sea. Our SNP survey showed that the majority of Icelandic eels are pure European eels but there is also an important contribution of individuals of admixed ancestry (10.7%). Although most of the hybrids were identified as F1 hybrids from European eel female × American eel male crosses, backcrosses were also detected, including a first-generation backcross (F1 hybrid × pure European eel) and three individuals identified as second-generation backcrosses originating from American eel × F1 hybrid backcrosses interbreeding with pure European eels. In comparison, no hybrids were observed in the Faroe Islands, the closest bodies of land to Iceland. It is possible that hybrids show an intermediate migratory behaviour between the two parental species that ultimately brings hybrid larvae to the shores of Iceland, situated roughly halfway between the Sargasso Sea and Europe. Only two hybrids were observed among Sargasso Sea larvae, both backcrosses, but no F1 hybrids, that points to temporal variation in the occurrence of hybridization. PMID:24424165

  16. Assessing patterns of hybridization between North Atlantic eels using diagnostic single-nucleotide polymorphisms

    PubMed Central

    Pujolar, J M; Jacobsen, M W; Als, T D; Frydenberg, J; Magnussen, E; Jónsson, B; Jiang, X; Cheng, L; Bekkevold, D; Maes, G E; Bernatchez, L; Hansen, M M

    2014-01-01

    The two North Atlantic eel species, the European eel (Anguilla anguilla) and the American eel (Anguilla rostrata), spawn in partial sympatry in the Sargasso Sea, providing ample opportunity to interbreed. In this study, we used a RAD (Restriction site Associated DNA) sequencing approach to identify species-specific diagnostic single-nucleotide polymorphisms (SNPs) and design a low-density array that combined with screening of a diagnostic mitochondrial DNA marker. Eels from Iceland (N=159) and from the neighboring Faroe Islands (N=29) were genotyped, along with 94 larvae (49 European and 45 American eel) collected in the Sargasso Sea. Our SNP survey showed that the majority of Icelandic eels are pure European eels but there is also an important contribution of individuals of admixed ancestry (10.7%). Although most of the hybrids were identified as F1 hybrids from European eel female × American eel male crosses, backcrosses were also detected, including a first-generation backcross (F1 hybrid × pure European eel) and three individuals identified as second-generation backcrosses originating from American eel × F1 hybrid backcrosses interbreeding with pure European eels. In comparison, no hybrids were observed in the Faroe Islands, the closest bodies of land to Iceland. It is possible that hybrids show an intermediate migratory behaviour between the two parental species that ultimately brings hybrid larvae to the shores of Iceland, situated roughly halfway between the Sargasso Sea and Europe. Only two hybrids were observed among Sargasso Sea larvae, both backcrosses, but no F1 hybrids, that points to temporal variation in the occurrence of hybridization. PMID:24424165

  17. Demographic characteristics of American eel in the Potomac River drainage, Virginia

    USGS Publications Warehouse

    Goodwin, K.R.; Angermeier, P.L.

    2003-01-01

    Studies of the demographic characteristics of the American eel Anguilla rostrata over broad spatial scales are scarce. Eels in the Shenandoah River drainage and lower Potomac River tributaries of Virginia were sampled over 2 years in both inland and near-coastal areas to describe the demographic characteristics in each area and document drainagewide patterns. Eels from the inland Shenandoah River drainage were significantly longer (median = 767 mm total length) and older (median = 11.5 years) than those found in the near-coastal Potomac River tributaries (median total length = 142 mm; median age = 2.0 years). In addition, the sex ratio varied in Potomac River tributaries, but only female were found in the Shenandoah River drainage. Catch per unit effort decreased with increasing distance inland and was further depressed upstream of some dams. Eel demographics in the Shenandoah drainage were similar to those observed in other studies done at distances exceeding 300 river kilometers (rkm) inland, whereas the demographics of Potomac River tributary eels were similar to those observed in other coastal and near-coastal areas. Large female eels found 300-500 rkm inland in this study may be especially important to the population's reproductive potential because of their greater fecundity. Investigations aimed at describing the demographics of eels in a region should sample throughout drainages to ensure accurate characterization. Effective management of eels will require innovative approaches that recognize the large-scale, complex structure of the population.

  18. Male- and female-derived somatic and germ cell-specific toxicity of silver nanoparticles in mouse.

    PubMed

    Han, Jae Woong; Jeong, Jae-Kyo; Gurunathan, Sangiliyandi; Choi, Yun-Jung; Das, Joydeep; Kwon, Deug-Nam; Cho, Ssang-Goo; Park, Chankyu; Seo, Han Geuk; Park, Jin-Ki; Kim, Jin-Hoi

    2016-04-01

    Silver nanoparticles (AgNPs) are widely used as an antibiotic agent in textiles, wound dressings, medical devices, and appliances such as refrigerators and washing machines. The increasing use of AgNPs has raised concerns about their potential risks to human health. Therefore, this study was aimed to determine the impact of AgNPs in germ cell specific complications in mice. The administration of AgNPs results in toxicity in mice; however, a more detailed understanding of the effects of AgNPs on germ cells remains poorly understood. Here, we demonstrate the effects of AgNPs (20 nm in diameter) in a mouse Sertoli and granulosa cells in vitro, and in male and female mice in vivo. Soluble silver ion (Ag(+))-treated cells were used as a positive control. We found that excessive AgNP-treated cells exhibited cytotoxicity, the formation of autophagosomes and autolysosomes in Sertoli cells. Furthermore, an increase in mitochondrial-mediated apoptosis by cytochrome c release from mitochondria due to translocation of Bax to mitochondria was observed. In in vivo studies, the expression of pro-inflammatory cytokines, including tumor necrosis factor α, interferon-γ, -6, -1β, and monocyte chemoattractant protein-1 were significantly increased (p < 0.05). Histopathological analysis of AgNP-treated mice shows that a significant loss of male and female germ cells. Taken together, these data suggest that AgNPs with an average size of 20 nm have negative impact on the reproduction. PMID:26470004

  19. Epidemiology of Anguillicola crassus in the European eel (Anguilla anguilla) from two rivers in southern England.

    PubMed

    Norton, J; Rollinson, D; Lewis, J W

    2005-06-01

    European eels Anguilla anguilla from the rivers Thames and Test, in the south of England, were examined between 2000 and 2003 for infection with the swim-bladder nematode Anguillicola crassus. Since its introduction to Thames eels at tidal estuarine locations circa 1987, A. crassus has become established in non-tidal freshwater stretches upriver and data from these locations are reported for the first time. The prevalence of infection at Thames estuary locations was higher during 2000-2003 than for the period 1987-1992. By 2003, similar prevalences were observed at freshwater and estuarine locations, but infection intensities were significantly higher in freshwater. Eels from the river Test appear to have been recently colonized by A. crassus (circa 2000). Parasite population establishment within these eels was uncharacteristically slow during 2000-2001, with low prevalence and intensity of infection, and few gravid females during this period. By 2003, infection levels in Test eels were similar to those in Thames eels. The expansion of the A. crassus population in Test eels has occurred in the absence of the paratenic host ruffe Gymnocephalus cernuus, and at suboptimal pH for the survival and infectivity of free-living larvae. The epidemiology of A. crassus in Test eels demonstrates that transmission of A. crassus by ruffe is not required for high prevalence and intensity of infection in eels. However, the consistently low and atypical levels of infection in Test eels during 2000 and 2001 suggests that paratenic transmission by ruffe may provide a substantial contribution to the dynamics of A. crassus in eels in the early years following introduction, by facilitating the rapid increase in prevalence and intensity of A. crassus infection that typically occurs during this time. PMID:15977905

  20. Fecundity of the American eel Anguilla rostrata at 45°N in Maine, U.S.A.

    USGS Publications Warehouse

    Barbin, G.P.; McCleave, J.D.

    1997-01-01

    The northern portion of the geographic range of the American eel Anguilla rostrata may contribute a great proportion of the reproductive potential to this panmictic species because of apparent increases in average female size and female percentage with latitude. The regressions of fecundity on body length and on body weight of 63 female eels captured at about 45° N latitude on their spawning migration to the sea were log F= 1·2601 + 2·9642 log L and log F= 4·1646+0·9153 log W, where F is fecundity, L is total length (cm), and W is total weight (g). Length and weight each explained about 90% of the variation in fecundity. Estimates of fecundity from counts of aliquots of eggs ranged from 1·84 million to 19·92 million eggs for eels ranging in length from 45 to 113 cm, nearly the range of sizes of migrating females reported in the literature. Fecundities of the American eel were greater than reported in one study at about 37° N and greater than reported for the European eel, A. anguilla, shortfin eel, A. australis, and longfin eel, A. dieffenbachii. If a geographic cline in fecundity does exist in American eels, it is established anew each generation because the species forms a single panmictic population.

  1. A ZZ-ZW sex chromosome system in the finless eel Dalophis imberbis (Anguilliformes, Ophichtidae).

    PubMed

    Salvadori, S; Coluccia, E; Cannas, R; Cau, A; Deiana, A M

    2009-04-01

    The karyotype of the finless eel Dalophis imberbis was investigated by conventional (C and replication banding, CMA(3) fluorescence) and molecular (FISH with 45S rDNA probe) techniques. The diploid chromosome number was 2n = 46 and the karyotype consisted of four pairs of meta-submetacentric and 18 pairs of subtelo-acrocentric autosomes and a pair of sex chromosomes heteromorphic in females, composed by a large subtelocentric Z, and a medium sized acrocentric W chromosome; in males this pair was composed by two large subtelocentric ZZ chromosomes. Multiple NORs have been localized by FISH and have been found to be CMA(3) positive; one of the NORs was located on the W chromosome and it was found transcriptionally active by silver staining. The Z chromosome contained distinct intercalar C-positive heterochromatin and W was almost completely heterochromatic. Our report contributes to the knowledge to the cytotaxonomy of Anguilliformes where differentiated sex chromosomes are reported in about a quarter of the species: both male and female heterogamety as well as a multiple chromosome system have been reported. Moreover, this is the first anguilliform species in which multiple NORs have been reported. PMID:18500652

  2. Glass-eel-stage American Eels respond to conspecific odor as a function of concentration

    USGS Publications Warehouse

    Schmucker, Andrew K; Johnson, Nicholas; Galbraith, Heather S.; Li, Weiming

    2016-01-01

    The American Eel Anguilla rostrata has experienced staggering population declines in recent decades and is now the focus of restoration efforts. Studies have demonstrated that olfaction is critical to anguillid behavior and that glass eels (the life stage which migrates inland from saltwater to freshwater) are attracted to conspecific washings. We evaluated conspecific cueing as a potential mechanism for American Eel inland migration coordination by assessing (1) the affinity of glass eels to conspecific washings, (2) the concentration–response relationships, and (3) changes in responsiveness to washings during the glass eel-to-elver transition. In two-choice maze assays, glass eels were attracted to glass eel washings over a wide range of concentrations (0.20–0.40 g of glass eels·L−1·h−1), and a logarithmic function provided the best fit to the concentration–response relationship. When given a choice between two conspecific washings of higher and lower concentrations, the glass eels generally preferred the higher concentration. Responses to undiluted glass eel washings did not significantly differ among stage-3–7 glass eels, although stage-7 eels were not attracted to the washings, whereas the other stages were. Washing affinity remained similar over the course of several weeks. These results support aspects of the conspecific cueing hypothesis at the glass eel life stage under laboratory conditions, suggesting that conspecific cueing is an important component of migration coordination among juvenile American Eels and warrants additional study.

  3. Random amplified polymorphic DNA analysis of eel genome.

    PubMed

    Qui, J J; Li, Y P

    1999-09-01

    Eel family is a huge one, in which many kinds of eels especially some migratory eels, bear strong resemblance to each other, and are therefore difficult to be identified. In this study 29 random primers were used to make RAPD analysis for Japanese eel (Anguilla japonica), European eel (Anguilla anguilla) and Pike eel (Muraenesox cinereus). And totally 299 fragments were counted. Shared or specific fragments were counted and genetic similarity or genetic distance were calculated. The genetic similarity between Japanese eel and Pike eel is 0.68 and the genetic distance between them is 0.32; those between European eel and Pike eel are 0.72 and 0.28 respectively, and between Japanese eel and European eel are 0.74 and 0.25 respectively. The method has been shown to be suitable to molecular identification of eels. It provides an alternative approach to determine the relationship between species. PMID:10520604

  4. Passage of downstream migrant American eels through an airlift-assisted deep bypass

    USGS Publications Warehouse

    Haro, Alexander J.; Watten, Barnaby J.; Noreika, John

    2016-01-01

    Traditional downstream guidance and bypass facilities for anadromous fishes (i.e., surface bypasses, surface guidance structures, and behavioral barriers) have frequently been ineffective for anguillid eels. Because eels typically spend the majority of their time near the bottom in the vicinity of intake structures, deep bypass structures with entrances near the bottom hold promise for increased effectiveness, thereby aiding in the recovery of this important species. A new design of a deep bypass system that uses airlift technology (the Conte Airlift Bypass) to induce flow in a bypass pipe was tested in a simulated intake entrance environment under controlled laboratory conditions. Water velocities of 0.9–1.5 m s−1 could be generated at the bypass entrance (opening with 0.073 m2 area), with corresponding flows through the bypass pipe of 0.07–0.11 m3 s−1. Gas saturation and hydrostatic pressure within the bypass pipe did not vary appreciably from a control (no air) condition under tested airflows. Migratory silver-phase American eels (Anguilla rostrata) tested during dark conditions readily located, entered, and passed through the bypass; initial avoidance rates (eels approaching but not entering the bypass entrance) were lower at higher entrance velocities. Eels that investigated the bypass pipe entrance tended to enter headfirst, but those that then exited the pipe upstream did so more frequently at lower entrance velocities. Eels appeared to swim against the flow while being transported downstream through the pipe; median transit times through the bypass for each test velocity ranged from 5.8 to 12.2 s, with transit time decreasing with increasing entrance velocity. Eels did not show strong avoidance of the vertical section of the pipe which contained injected air. No mortality or injury of bypassed eels was observed, and individual eels repeatedly passed through the bypass at rates of up to 40 passes per hour, suggesting that individuals do not

  5. EELS from organic crystalline materials

    NASA Astrophysics Data System (ADS)

    Brydson, R.; Eddleston, M. D.; Jones, W.; Seabourne, C. R.; Hondow, N.

    2014-06-01

    We report the use of the electron energy loss spectroscopy (EELS) for providing light element chemical composition information from organic, crystalline pharmaceutical materials including theophylline and paracetamol and discuss how this type of data can complement transmission electron microscopy (TEM) imaging and electron diffraction when investigating polymorphism. We also discuss the potential for the extraction of bonding information using electron loss near-edge structure (ELNES).

  6. Correlated optical measurements and plasmon mapping of silver nanorods

    SciTech Connect

    Guiton, Beth S; Iberi, Vighter; Li, Shuzhou; Leonard, Donovan N; Parish, Chad M; Kotula, Paul G; Varela del Arco, Maria; Schatz, George C.; Pennycook, Stephen J; Camden, Jon P

    2011-01-01

    Plasmonics is a rapidly growing field, yet imaging of the plasmonic modes in complex nanoscale architectures is extremely challenging. Here we obtain spatial maps of the localized surface plasmon modes of high-aspect-ratio silver nanorods using electron energy loss spectroscopy (EELS) and correlate to optical data and classical electrodynamics calculations from the exact same particles. EELS mapping is thus demonstrated to be an invaluable technique for elucidating complex and overlapping plasmon modes.

  7. Ultrasonographic predictors of response of European eels (Anguilla anguilla) to hormonal treatment for induction of ovarian development.

    PubMed

    Müller, Anna V; McEvoy, Fintan J; Tomkiewicz, Jonna; Politis, Sebastian N; Amigo, José M

    2016-05-01

    OBJECTIVE To examine ultrasonographic predictors of ovarian development in European eels (Anguilla anguilla) undergoing hormonal treatment for assisted reproduction. ANIMALS 83 female European eels. PROCEDURES Eels received weekly IM injections of salmon pituitary extract (first injection = week 1). Ultrasonography of the ovaries was performed twice during hormonal treatment (weeks 7 and 11). Eels were identified on the basis of body weight as having an adequate response by weeks 14 to 20 or an inadequate response after injections for 21 weeks. Eels were euthanized at the end of the experiment and classified by use of ovarian histologic examination. Ovarian cross-sectional area and size of eel (ie, length (3) ) were used to classify eels (fast responder, slow responder, or nonresponder) and to calculate an ultrasonographic-derived gonadosomatic index. Gray-level co-occurrence matrices were calculated from ovarian images, and 22 texture features were calculated from these matrices. RESULTS The ultrasonographic-derived gonadosomatic index differed significantly between fast responders and slow responders or nonresponders at both weeks 7 and 11. Principal component analysis revealed a pattern of separation between the groups, and partial least squares discriminant analysis revealed signals in the ovarian texture that discriminated females that responded to treatment from those that did not. CONCLUSIONS AND CLINICAL RELEVANCE Ovarian texture information in addition to morphometric variables can enhance ultrasonographic applications for assisted reproduction of eels and potentially other fish species. This was a novel, nonlethal method for classifying reproductive response of eels and the first objective texture analysis performed on ultrasonographic images of the gonads of fish. PMID:27111015

  8. A question of origin: dioxin-like PCBs and their relevance in stock management of European eels.

    PubMed

    Freese, Marko; Sühring, Roxana; Pohlmann, Jan-Dag; Wolschke, Hendrik; Magath, Victoria; Ebinghaus, Ralf; Hanel, Reinhold

    2016-01-01

    The stock of European Eel (Anguilla anguilla L.) has reached an all-time low in 2011. Spawner quality of mature eels in terms of health status and fitness is considered one of the key elements for successful migration and reproduction. Dioxin-like Polychlorinated Biphenyls (dl-PCBs) are known persistent organic pollutants potentially affecting the reproductive capability and health status of eels throughout their entire lifetime. In this study, muscle tissue samples of 192 European eels of all continental life stages from 6 different water bodies and 13 sampling sites were analyzed for contamination with lipophilic dl-PCBs to investigate the potential relevance of the respective habitat in light of eel stock management. Results of this study reveal habitat-dependent and life history stage-related accumulation of targeted PCBs. Sum concentrations of targeted PCBs differed significantly between life stages and inter-habitat variability in dl-PCB levels and -profiles was observed. Among all investigated life stages, migrant silver eels were found to be the most suitable life history stage to represent their particular water system due to habitat dwell-time and their terminal contamination status. With reference to a possible negative impact of dl-PCBs on health and the reproductive capability of eels, it was hypothesized that those growing up in less polluted habitats have a better chance to produce healthy offspring than those growing up in highly polluted habitats. We suggest that the contamination status of water systems is fundamental for the life cycle of eels and needs to be considered in stock management and restocking programs. PMID:26477019

  9. Geothermal eel farm in Slovakia

    SciTech Connect

    Lund, J.W.; Thomka, J.; Sarlinova, K.

    1998-12-01

    Turcianske Teplice, a small town in west-central Slovakia, has written records of using thermal waters since 1281. In 1992, an eel raising farm was started on the outskirts of the town and since 1994, it has been operated by the firm of Janex Slovensko. The farm, using a specialized water recirculation system, raises a species of migrating eels (Anguilla anguilla). A 220-meter deep well at 42 C provides 48 gpm to the facility for heating through a plate heat exchanger. This is the maximum flow permitted, so as not to influence the springs and wells at the spa about 1 km away. For this reason, the flow is monitored carefully by the state. A second geothermal well at 52 C and 1,500 meters deep is used only as an observation well. Cold water, which is heated by the geothermal water, is pumped from wells near the Turiec River 1.8 km away at 8 to 12 C, depending upon the season, for use in the various holding or raising tanks. The operation of the farm is described.

  10. Magnetic compass orientation in the European eel.

    PubMed

    Durif, Caroline M F; Browman, Howard I; Phillips, John B; Skiftesvik, Anne Berit; Vøllestad, L Asbjørn; Stockhausen, Hans H

    2013-01-01

    European eel migrate from freshwater or coastal habitats throughout Europe to their spawning grounds in the Sargasso Sea. However, their route (~ 6000 km) and orientation mechanisms are unknown. Several attempts have been made to prove the existence of magnetoreception in Anguilla sp., but none of these studies have demonstrated magnetic compass orientation in earth-strength magnetic field intensities. We tested eels in four altered magnetic field conditions where magnetic North was set at geographic North, South, East, or West. Eels oriented in a manner that was related to the tank in which they were housed before the test. At lower temperature (under 12°C), their orientation relative to magnetic North corresponded to the direction of their displacement from the holding tank. At higher temperatures (12-17°C), eels showed bimodal orientation along an axis perpendicular to the axis of their displacement. These temperature-related shifts in orientation may be linked to the changes in behavior that occur between the warm season (during which eels are foraging) and the colder fall and winter (during which eels undertake their migrations). These observations support the conclusion that 1. eels have a magnetic compass, and 2. they use this sense to orient in a direction that they have registered moments before they are displaced. The adaptive advantage of having a magnetic compass and learning the direction in which they have been displaced becomes clear when set in the context of the eel's seaward migration. For example, if their migration is halted or blocked, as it is the case when environmental conditions become unfavorable or when they encounter a barrier, eels would be able to resume their movements along their old bearing when conditions become favorable again or when they pass by the barrier. PMID:23554997

  11. Histological and hormonal changes in the European eel (Anguilla anguilla) after exposure to environmental cocaine concentration.

    PubMed

    Gay, F; Ferrandino, I; Monaco, A; Cerulo, M; Capasso, G; Capaldo, A

    2016-03-01

    The aim of this study was the assessment of histological and hormonal changes induced in the European eel from environmental concentrations of cocaine. Silver eels were exposed to 20 ng L(-1) of cocaine during 50 days; at the same time, control, vehicle control and two post-exposure recovery groups (3 and 10 days) were made. The general morphology of the skin and the intestine, and the plasma levels of prolactin, cortisol and dopamine were evaluated. In the skin, cocaine decreased the number and size of mucous cells, increased the thickness of the epidermis and altered the club cells and the basal lamina. In the intestine, cocaine increased the thickness of the epithelium and the number of mucous cells and reactivated the structure of the intestine and of the intestinal musculature. Moreover, cocaine increased plasma prolactin, cortisol and dopamine levels. These results suggest that cocaine induced histological changes, directly and/or through the hormonal changes observed. Considering the complex life cycle of the eel, the changes induced by cocaine in the skin, the intestine and the endocrine system could threaten the ability of the eel to successfully migrate and reproduce. PMID:25865023

  12. An evaluation of indices of gross pathology associated with the nematode Anguillicoloides crassus in eels.

    PubMed

    Lefebvre, F; Fazio, G; Palstra, A P; Székely, C; Crivelli, A J

    2011-01-01

    This study compares two alternative indices for quantifying the gross pathology of the swimbladder of eels, Anguilla anguilla (L.), infected with the nematode Anguillicoloides crassus. Two observers recorded twice the scores obtained by the two indices on the same set of 71 wild caught eels (from elver to silver eels, French Mediterranean lagoons). The Length Ratio Index (LRI), performed better than the Swimbladder Degenerative Index (SDI), in three of four predefined criteria of decision. First, the LRI better correlated with an estimate of the swimbladder volume reduction, a functional consequence of the infection (representativeness). Also, the LRI was less prone to subjectivity (inter-observer variability) and more precise (intra-observer variability), although less easy to generate (time needed for measurement/assessment). Using a sub-sample of 32 unaffected eels (showing minor if any swimbladder damage and no living worms at autopsy), we ascertained a linear relationship between the swimbladder length and the total body length, a prerequisite of isometric growth, to definitively accept the new ratio index as a valid alternative to the SDI. Also, because the LRI can be recorded on live specimens with radio-imagery (non-invasive method), we recommend its use, and provide a graph of correspondence between the SDI scores, the LRI scores and the estimated proportion of gas loss in the swimbladder. PMID:21118268

  13. Magnetic Compass Orientation in the European Eel

    PubMed Central

    Durif, Caroline M. F.; Browman, Howard I.; Phillips, John B.; Skiftesvik, Anne Berit; Vøllestad, L. Asbjørn; Stockhausen, Hans H.

    2013-01-01

    European eel migrate from freshwater or coastal habitats throughout Europe to their spawning grounds in the Sargasso Sea. However, their route (∼ 6000 km) and orientation mechanisms are unknown. Several attempts have been made to prove the existence of magnetoreception in Anguilla sp., but none of these studies have demonstrated magnetic compass orientation in earth-strength magnetic field intensities. We tested eels in four altered magnetic field conditions where magnetic North was set at geographic North, South, East, or West. Eels oriented in a manner that was related to the tank in which they were housed before the test. At lower temperature (under 12°C), their orientation relative to magnetic North corresponded to the direction of their displacement from the holding tank. At higher temperatures (12–17°C), eels showed bimodal orientation along an axis perpendicular to the axis of their displacement. These temperature-related shifts in orientation may be linked to the changes in behavior that occur between the warm season (during which eels are foraging) and the colder fall and winter (during which eels undertake their migrations). These observations support the conclusion that 1. eels have a magnetic compass, and 2. they use this sense to orient in a direction that they have registered moments before they are displaced. The adaptive advantage of having a magnetic compass and learning the direction in which they have been displaced becomes clear when set in the context of the eel’s seaward migration. For example, if their migration is halted or blocked, as it is the case when environmental conditions become unfavorable or when they encounter a barrier, eels would be able to resume their movements along their old bearing when conditions become favorable again or when they pass by the barrier. PMID:23554997

  14. Application of STEM/EELS to Plasmon-Related Effects in Optical Spectroscopy

    SciTech Connect

    Camden, Jon P.

    2015-01-29

    The last decade has seen an explosion in the study of plasmonic materials, with current applications including surface-enhanced spectroscopy, imaging beyond the diffraction limit, solar energy harvesting, and ultrasensitive detection. This proposal utilizes electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) to explore the near-field enhancements encountered upon excitation of the localized surface plasmon resonance. In particular we have studied Fano interferences using optical and electron energy-loss spectroscopies (EELS). Single silver nanocubes were utilized in this study due to the substrate-mediated hybridization of the primitive dipolar and quadrupolar plasmon modes that give rise to the Fano phenomenon. The cube at substrate system provides a unique opportunity to study the plasmonic energy transfer from metallic nanoparticles to neighboring materials, which is an essential component of plasmon-enhanced solar harvesting devices.

  15. Differential gene expression analysis in European eels (Anguilla anguilla, L. 1758) naturally infected by macroparasites.

    PubMed

    Fazio, G; Moné, H; Lecomte-Finiger, R; Sasal, P

    2008-06-01

    We analyzed the relationships between the macroparasite community of the European eel and the expression of genes involved in the host physiology during its continental life. The genes studied are implicated in (1) host response to environmental stress, i.e., heat shock protein 70 (HSP70) and metallothionein (MT); (2) osmoregulation, i.e., beta thyroid hormone receptor (betaTHR) and Na+/K+ATPase; and (3) silvering, i.e., betaTHR, freshwater rod opsin (FWO), and deep-sea rod opsin (DSO). All were enumerated by quantitative reverse-transcription polymerase chain reaction. The epizootiological results for 93 yellow eels caught in the Salses-Leucate Lagoon (France) included 11 species: 1 nematode, 2 acanthocephalans, 1 monogenean, and 7 digeneans. The molecular results revealed (1) a significant negative relationship between digenean abundance and the expression level of all the tested genes, except FWO; (2) a significant negative relationship between the abundance of the nematode Anguillicola crassus and the expression level of the Na+/K+ATPase gene; and (3) a significant positive relationship between the A. crassus abundance and the expression level of the MT gene. Eels infected with digeneans had, on average, a lower level of expressed genes. We hypothesize that the parasites may disturb the eel's ability to withstand environmental stress and delay their migration to the Sargasso Sea because of degeneration of the gut. We further propose that the effect of the invasive species, A. crassus, on the gene expression was mainly linked to an increased trophic activity of infected eels. Moreover, it is possible that the parasite may have an effect on the fish's migratory behavior, which is tied to reproductive purposes. Additional work, including an experimental approach, is required to confirm our hypotheses. PMID:18605780

  16. 33 CFR 117.598 - Eel Pond Channel.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  17. 33 CFR 117.598 - Eel Pond Channel.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  18. 33 CFR 117.598 - Eel Pond Channel.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  19. 33 CFR 117.598 - Eel Pond Channel.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  20. 33 CFR 117.598 - Eel Pond Channel.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  1. Toxic Effects of Silver Nanoparticles on Liver and Some Hematological Parameters in Male and Female Mice (Mus musculus).

    PubMed

    Heydrnejad, M Saeed; Samani, Roya Jafarzadeh; Aghaeivanda, Simin

    2015-06-01

    This research was carried out to evaluate toxic effects of nanosilver (Ag-NPs) on liver function and some blood parameters of male and female mice Mus musculus. A group of 54 BALB/c mice was randomly divided into three groups (each with two replications): Ag-NP (2) and control (1), each with nine mice. The experiment lasted for 14 days. In the treatment groups, two different doses of 20 and 50 ppm of Ag-NP solution were administered orally, while in the untreated (control) group, no Ag-NP solution but distilled water was used. At the end of the experiment, the serum was obtained by centrifugation of the whole blood at 3000 rpm for 15 min. The biochemical levels including alanine aminotransferase (ALT), aspartate amino transferase (AST), and blood cells were assayed by an automatic biochemical analyzer. Also, liver biopsy was performed and samples were stained using hematoxylin and eosin (H&E) staining. The values of red blood cells (RBC), hemoglobin (Hb), and hematocrit (Hct) did not vary significantly in the control and Ag-NP-treated animals. There were significant changes in the treatment and control groups in the levels of liver enzymes so that at both doses, there were significantly elevated levels of ALT and AST in mice treated with Ag-NPs compared with the control (p < 0.05). Sexuality was not significantly involved in the results. Oral exposure to Ag-NPs produced changes in blood chemistry and hepatotoxicity as indicated by increased serum activity levels of both AST and ALT and histological damages to the liver with no significant changes between male and female mice. PMID:25637567

  2. Duplicated Leptin Receptors in Two Species of Eel Bring New Insights into the Evolution of the Leptin System in Vertebrates

    PubMed Central

    Morini, Marina; Pasquier, Jérémy; Dirks, Ron; van den Thillart, Guido; Tomkiewicz, Jonna; Rousseau, Karine; Dufour, Sylvie; Lafont, Anne-Gaëlle

    2015-01-01

    Since its discovery in mammals as a key-hormone in reproduction and metabolism, leptin has been identified in an increasing number of tetrapods and teleosts. Tetrapods possess only one leptin gene, while most teleosts possess two leptin genes, as a result of the teleost third whole genome duplication event (3R). Leptin acts through a specific receptor (LEPR). In the European and Japanese eels, we identified two leptin genes, and for the first time in vertebrates, two LEPR genes. Synteny analyses indicated that eel LEPRa and LEPRb result from teleost 3R. LEPRb seems to have been lost in the teleost lineage shortly after the elopomorph divergence. Quantitative PCRs revealed a wide distribution of leptins and LEPRs in the European eel, including tissues involved in metabolism and reproduction. Noticeably, leptin1 was expressed in fat tissue, while leptin2 in the liver, reflecting subfunctionalization. Four-month fasting had no impact on the expression of leptins and LEPRs in control European eels. This might be related to the remarkable adaptation of silver eel metabolism to long-term fasting throughout the reproductive oceanic migration. In contrast, sexual maturation induced differential increases in the expression of leptins and LEPRs in the BPG-liver axis. Leptin2 was strikingly upregulated in the liver, the central organ of the reproductive metabolic challenge in teleosts. LEPRs were differentially regulated during sexual maturation, which may have contributed to the conservation of the duplicated LEPRs in this species. This suggests an ancient and positive role of the leptin system in the vertebrate reproductive function. This study brings new insights on the evolutionary history of the leptin system in vertebrates. Among extant vertebrates, the eel represents a unique case of duplicated leptins and leptin receptors as a result of 3R. PMID:25946034

  3. Duplicated leptin receptors in two species of eel bring new insights into the evolution of the leptin system in vertebrates.

    PubMed

    Morini, Marina; Pasquier, Jérémy; Dirks, Ron; van den Thillart, Guido; Tomkiewicz, Jonna; Rousseau, Karine; Dufour, Sylvie; Lafont, Anne-Gaëlle

    2015-01-01

    Since its discovery in mammals as a key-hormone in reproduction and metabolism, leptin has been identified in an increasing number of tetrapods and teleosts. Tetrapods possess only one leptin gene, while most teleosts possess two leptin genes, as a result of the teleost third whole genome duplication event (3R). Leptin acts through a specific receptor (LEPR). In the European and Japanese eels, we identified two leptin genes, and for the first time in vertebrates, two LEPR genes. Synteny analyses indicated that eel LEPRa and LEPRb result from teleost 3R. LEPRb seems to have been lost in the teleost lineage shortly after the elopomorph divergence. Quantitative PCRs revealed a wide distribution of leptins and LEPRs in the European eel, including tissues involved in metabolism and reproduction. Noticeably, leptin1 was expressed in fat tissue, while leptin2 in the liver, reflecting subfunctionalization. Four-month fasting had no impact on the expression of leptins and LEPRs in control European eels. This might be related to the remarkable adaptation of silver eel metabolism to long-term fasting throughout the reproductive oceanic migration. In contrast, sexual maturation induced differential increases in the expression of leptins and LEPRs in the BPG-liver axis. Leptin2 was strikingly upregulated in the liver, the central organ of the reproductive metabolic challenge in teleosts. LEPRs were differentially regulated during sexual maturation, which may have contributed to the conservation of the duplicated LEPRs in this species. This suggests an ancient and positive role of the leptin system in the vertebrate reproductive function. This study brings new insights on the evolutionary history of the leptin system in vertebrates. Among extant vertebrates, the eel represents a unique case of duplicated leptins and leptin receptors as a result of 3R. PMID:25946034

  4. Recruitment collapse and population structure of the European eel shaped by local ocean current dynamics.

    PubMed

    Baltazar-Soares, Miguel; Biastoch, Arne; Harrod, Chris; Hanel, Reinhold; Marohn, Lasse; Prigge, Enno; Evans, Derek; Bodles, Kenneth; Behrens, Erik; Böning, Claus W; Eizaguirre, Christophe

    2014-01-01

    Worldwide, exploited marine fish stocks are under threat of collapse [1]. Although the drivers behind such collapses are diverse, it is becoming evident that failure to consider evolutionary processes in fisheries management can have drastic consequences on a species' long-term viability [2]. The European eel (Anguilla anguilla; Linnaeus, 1758) is no exception: not only does the steep decline in recruitment observed in the 1980s [3, 4] remain largely unexplained, the punctual detection of genetic structure also raises questions regarding the existence of a single panmictic population [5-7]. With its extended Transatlantic dispersal, pinpointing the role of ocean dynamics is crucial to understand both the population structure and the widespread decline of this species. Hence, we combined dispersal simulations using a half century of high-resolution ocean model data with population genetics tools. We show that regional atmospherically driven ocean current variations in the Sargasso Sea were the major driver of the onset of the sharp decline in eel recruitment in the beginning of the 1980s. The simulations combined with genotyping of natural coastal eel populations furthermore suggest that unexpected evidence of coastal genetic differentiation is consistent with cryptic female philopatric behavior within the Sargasso Sea. Such results demonstrate the key constraint of the variable oceanic environment on the European eel population. PMID:24374306

  5. Application of talcum powder, trichloroacetic acid and silver nitrate in female rats for non-surgical sterilization: evaluation of the apoptotic pathway mRNA and miRNA genes.

    PubMed

    Yumrutas, Onder; Kara, Murat; Atilgan, Remzi; Kavak, Salih Burcin; Bozgeyik, Ibrahim; Sapmaz, Ekrem

    2015-04-01

    There are several methods used for non-surgical sterilization in birth control including quinacrine, trichloroacetic acid (TCA), erythromycin, tetracycline, silver nitrate and talcum powder. Among these, talcum powder, TCA and silver nitrate are the most commonly used. However, the toxic and carcinogenic activities of these chemicals in ovarian tissue have been poorly elucidated. This study demonstrates the expression levels of antioxidant, apoptotic and anti-apoptotic genes after administration of talc powder, TCA and silver nitrate for non-surgical sterilization in female rat models. The expression changes of some microRNAs (miR-15b, miR-21, miR-34a and miR-98) that play key roles in the apoptosis pathway were also included. All expression analyses were evaluated with real-time PCR. The expression levels of all genes appeared to be upregulated in the talcum powder group, but the results were not statistically significant. Increased expression of Gsr and Sod1 genes was statistically significant in the talcum powder group. In TCA and silver nitrate group, expression of all genes was appeared to be elevated but only the Gsr expression was statistically significant in the TCA-administrated group; there were no statistically significant changes in the silver nitrate group. miRNA expression levels were increased in talcum powder and TCA-administrated groups, but these results were not significant. Expression levels of miR-15b, miR-21 and miR-98 in the silver nitrate group were significantly increased. Consequently, these chemicals appear to be non-carcinogenic agents for rat ovarian tissue which do not induce apoptosis. However, talcum powder and TCA can be considered as agents that are toxic to ovarian tissue. PMID:25885949

  6. Pop Up Satellite Tags Impair Swimming Performance and Energetics of the European Eel (Anguilla anguilla)

    PubMed Central

    Methling, Caroline; Tudorache, Christian; Skov, Peter V.; Steffensen, John F.

    2011-01-01

    Pop-up satellite archival tags (PSATs) have recently been applied in attempts to follow the oceanic spawning migration of the European eel. PSATs are quite large, and in all likelihood their hydraulic drag constitutes an additional cost during swimming, which remains to be quantified, as does the potential implication for successful migration. Silver eels (LT = 598.6±29 mm SD, N = 9) were subjected to swimming trials in a Steffensen-type swim tunnel at increasing speeds of 0.3–0.9 body lengths s−1, first without and subsequently with, a scaled down PSAT dummy attached. The tag significantly increased oxygen consumption (MO2) during swimming and elevated minimum cost of transport (COTmin) by 26%. Standard (SMR) and active metabolic rate (AMR) as well as metabolic scope remained unaffected, suggesting that the observed effects were caused by increased drag. Optimal swimming speed (Uopt) was unchanged, whereas critical swimming speed (Ucrit) decreased significantly. Swimming with a PSAT altered swimming kinematics as verified by significant changes to tail beat frequency (f), body wave speed (v) and Strouhal number (St). The results demonstrate that energy expenditure, swimming performance and efficiency all are significantly affected in migrating eels with external tags. PMID:21687674

  7. Silver Sulfadiazine

    MedlinePlus

    Silver sulfadiazine, a sulfa drug, is used to prevent and treat infections of second- and third-degree ... Silver sulfadiazine comes in a cream. Silver sulfadiazine usually is applied once or twice a day. Follow ...

  8. Maternal transfer of emerging brominated and chlorinated flame retardants in European eels.

    PubMed

    Sühring, Roxana; Freese, Marko; Schneider, Mandy; Schubert, Sophia; Pohlmann, Jan-Dag; Alaee, Mehran; Wolschke, Hendrik; Hanel, Reinhold; Ebinghaus, Ralf; Marohn, Lasse

    2015-10-15

    relevance as contaminants in eels and are transferred to eggs. A change of the isomer pattern in comparison to the technical product of Dechlorane Plus (DP) was observed indicating a redistribution of DP from muscle tissue to gonads during silvering with a preference of the syn-isomer. The highly bioaccumulative DDC-DBF was the most abundant Dechlorane in all fish of the comparison group even though it is not produced or imported in the EU. The aldrin related "experimental flame retardant" dibromoaldrin (DBALD) was detected for the first time in the environment in similar or higher concentrations than DP. PMID:26042896

  9. Corroded spent nuclear fuel examined with EELS

    SciTech Connect

    Buck, E.C.; Dietz, N.L.; Bates, J.K.

    1996-07-01

    Samples, exposed to dripping simulated groundwater, were prepared by ultramicrotomy for TEM. The alteration phase was identified as a layered Cs Mo uranyl oxide hydrate, structurally related to phases of the becquerelite group uranium minerals. Second-difference EELS of rare earth elements within the corroded particle detected low levels of TRUs.

  10. Expression of a duplicate Na,K-ATPase beta(1)-isoform in the European eel (Anguilla anguilla).

    PubMed

    Cutler, C P; Brezillon, S; Bekir, S; Sanders, I L; Hazon, N; Cramb, G

    2000-07-01

    Recent studies on teleost fish have suggested that their genomes have undergone ancient polyploidization events resulting in the duplication of the genome. A duplicate copy of the Na,K-ATPase beta(1)-isoform (called beta(233)) has been identified in the European eel (Anguilla anguilla). The beta(233)-isoform shares high levels of nucleotide (74.8%) and amino acid (69.9%) homology with the eel beta(1)-subunit as well as other vertebrate beta(1)-sequences. Compared with the widely expressed beta(1)-isoform, expression of beta(233)-mRNA is mainly restricted to epithelial tissues. Seawater acclimation induced increases in beta(233)-mRNA levels in kidney, gill, and intestine of migratory "silver" but not the nonmigratory "yellow" adult eels, suggesting that the factors responsible for this upregulation are themselves developmentally regulated. Expression of a variably glycosylated 40- to 52-kDa beta(233)-protein in both gill "chloride" and intestinal epithelial cells suggests that the beta(233)-isoform of Na,K-ATPase may play an important functional role in the major osmoregulatory tissues of euryhaline fish such as the eel. PMID:10896885

  11. Identification of gonadal soma-derived factor involvement in Monopterus albus (protogynous rice field eel) sex change.

    PubMed

    Zhu, Yefei; Wang, Chunlei; Chen, Xiaowu; Guan, Guijun

    2016-07-01

    We studied molecular events and potential mechanisms underlying the process of female-to-male sex transformation in the rice field eel (Monopterus albus), a protogynous hermaphrodite fish in which the gonad is initially a female ovary and transforms into male testes. We cloned and identified a novel gonadal soma derived factor (GSDF), which encodes a member of the transforming growth factor-beta superfamily. gsdf expression was measured in gonads of female, intersex and male with reverse transcription-PCR and gsdf's role in sex transformation was studied with qPCR, histological analysis and dual-color in situ hybridization assays and compared to other sex-related genes. gsdf was correlated to Sertoli cell differentiation, indicating involvement in testicular differentiation and sex transformation from female to male in this species. A unique expression pattern reveals a potential role of gsdf essential for the sex transformation of rice field eels. PMID:27230579

  12. Occurrence of POPs and other persistent organic contaminants in the European eel (Anguilla anguilla) from the Loire estuary, France.

    PubMed

    Couderc, M; Poirier, L; Zalouk-Vergnoux, A; Kamari, A; Blanchet-Letrouvé, I; Marchand, P; Vénisseau, A; Veyrand, B; Mouneyrac, C; Le Bizec, B

    2015-02-01

    The chemical contamination of the Loire estuary by three classes of persistent organic pollutants (POPs): the polychlorinated biphenyls (PCBs), the polybrominated diphenyl ethers (PBDEs) and the perfluorinated and polyfluorinated alkyl substances (PFAS), and three families of organic contaminants, the alkylphenols (APs), the polycyclic aromatic hydrocarbon metabolites (OH-PAHs) and the bisphenol A (BPA) were investigated in the muscles and bile of European eel (Anguilla anguilla). Yellow eels (n=30) were caught in three different points along the estuary to highlight variations between sites and sources of contaminations. Silver eels (n=15) were also studied to compare contaminant impregnation between different life stages of the species. Average concentrations in the muscles of the eel ranged between: 857 and 4358 ng/gLW for the PCBs, 26 and 46 ng/gLW for the PBDEs, 130 and 1293 ng/gLW for the PFAS; and in bile: 31 and 286 μg/g protein for the APs, 9 and 26 μg/g protein for the OH-PAHs and ND-1213 μg/g protein for the BPA. Among PCBs, PCB 153 (40% contribution to the sum of PCBs) was predominant in all eel muscles. PBDE 47 (60%) was the most predominant PBDE congeners, while perfluorooctanesulfonic acid (85%) was the most widely detected PFAS. For APs, 4p-nonylphenol (91%) was the most abundant and for the OH-PAHs, it was 1OH-Pyrene (63%). All the eels exceeded the environmental quality standards (EQS) for biota for the PBDEs and about 75% were higher than the EQS specific to PFOS. Finally, 20% of the analyzed eels presented TEQ concentrations above the maximum limits for lipid-rich species. These results supplied new data on the occurrence, levels, and patterns of 53 organic chemicals in the eels from the Loire estuary and they highlighted the need of further investigations focused notably on the potential effects of these chemicals on this species and their analysis in the water and sediments of the estuary. PMID:25461022

  13. Conclusive evidence for panmixia in the American eel.

    PubMed

    Pujolar, Jose M

    2013-04-01

    Eels are unique species in the biological world. The two North Atlantic eel species, the American eel (Anguilla rostrata) and the European eel (A. anguilla), occupy a broad range of habitats from the Caribbean to Greenland in the western Atlantic and from Morocco to Iceland in the eastern Atlantic, respectively. North Atlantic eels have a catadromous life cycle, spawning only in the Sargasso Sea and spending the majority of their lives in continental (fresh, brackish and coastal) waters. Despite such a wide distribution range, North Atlantic eels have been regarded as a textbook example of panmictic species. In contrast with the large amount of population genetic studies testing the panmixia hypothesis in the European eel, a relatively modest effort has been given to study the population structure of the American eel. In this issue of Molecular Ecology, C^ote et al. (2013) present the most comprehensive American eel data set to date, which includes samples of different life stages obtained throughout all its distribution range in North America. Results show a total lack of genetic differentiation among samples and provide decisive evidence for panmixia in the American eel. PMID:23620904

  14. Head shape dimorphism in European glass eels (Anguilla anguilla).

    PubMed

    De Meyer, J; Ide, C; Belpaire, C; Goemans, G; Adriaens, D

    2015-12-01

    The life cycle of the European eel (Anguilla anguilla) remained a mystery until the 20th century, when Schmidt discovered that the Sargasso Sea was its spawning area. However, many aspects of the eel's life cycle remain poorly understood. Among these is the bimodal distribution in head shape, with broad- and narrowheaded phenotypes reported in the yellow eel stage. Although this has been linked to dietary preferences of the yellow eels, very little is known about why, how and when this dimorphism arises during their ontogeny. To determine whether this dimorphism indeed appears in relation to trophic niche segregation, we examined head shape variation at an earlier ontogenetic stage, the glass eel stage, as at this stage eels are considered to be non-feeding. Head shape was studied in a large dataset, containing glass eels captured from the Yser river mouth, the Leopold Canal (Belgium) and from the rivers Severn, Trent and Parret (UK), by both taking measurements (head width/head length) and using an outline analysis. Our results show that there is already considerable variation in broadness and bluntness of the head at the glass eel stage. In most cases, equal support for a unimodal and bimodal head shape distribution is found, whereas some cases support head shape bimodality in glass eels, suggesting that glass eel head shape might be shifting from a unimodal to a bimodal distribution. This, in combination with the observation that variation in head width/head length ratios in non-feeding glass eels shows a similar range as in feeding yellow eels, indicates that head shape in European eel might be at least partially determined through other mechanisms than trophic segregation. PMID:26265585

  15. Toxicity of 5% rotenone to nonindigenous Asian swamp eels

    USGS Publications Warehouse

    Schofield, P.J.; Nico, L.G.

    2007-01-01

    Our primary goal was to determine whether rotenone would be a useful control against introduced populations of Asian swamp eels (family Synbranchidae, genus Monopterus). We report the results of a laboratory experiment comparing the efficacy of various rotenone concentrations (1, 2, 4, and 8 mg of 5% liquid rotenone/L of water) in killing nonindigenous swamp eels of various sizes (1-350 g) from the three known Florida populations. Although most small swamp eels were killed at concentrations of 2 and 4 mg/L. 100% mortality of adult swamp eels was achieved only at 8 mg/L. We conclude that the effective use of rotenone to control established Florida swamp eel populations would be difficult, based on the relatively high concentration of rotenone needed to kill swamp eels; the complexity of the swamp eel's habitat; and our observations of the species' habitat use and behavior, including its widespread distribution and life history characteristics (e.g., burrowing and overland movement) that enhance its invasion and survival in multiple environments. Nevertheless, control of swamp eels may be achieved in certain situations. A combination of rotenone and electroshocking may be an effective way to eradicate swamp eels from small water bodies and to control populations in larger habitats. However, we are cautious in this recommendation and provide details related to the technical aspects of this type of strategy and caveats related to the toxicity of the chemical.

  16. Proceedings of a workshop on American Eel passage technologies

    USGS Publications Warehouse

    Haro, Alexander J.

    2013-01-01

    Recent concerns regarding a decline in recruitment of American eels (Anguilla rostrata) have prompted efforts to restore this species to historic habitats by providing passage for both upstream migrant juveniles and downstream migrant adults at riverine barriers, including low-head and hydroelectric dams (Castonguay et al. 1994, Haro et al. 2000). These efforts include development of management plans and stock assessment reviews in both the US and Canada (COSEWIC 2006, Canadian Eel Working Group 2009, DFO 2010, MacGregor et al. 2010, ASMFC 2000, ASMFC 2006, ASMFC 2008, Williams and Threader 2007), which target improvement of upstream and downstream passage for eels, as well as identification and prioritization of research needs for development of new and more effective passage technologies for American eels. Traditional upstream fish passage structures, such as fishways and fish lifts, are often ineffective passing juvenile eels, and specialized passage structures for this species are needed. Although designs for such passage structures are available and diverse (Knights and White 1998, Porcher 2002, FAO/DVWK 2002, Solomon and Beach 2004a,b, Environment Agency UK 2011), many biologists, managers, and engineers are unfamiliar with eel pass design and operation, or unaware of the technical options available for upstream eel passage, Better coordination is needed to account for eel passage requirements during restoration efforts for other diadromous fish species. Also, appropriately siting eel passes at hydropower projects is critical, and siting can be difficult and complex due to physical restrictions in access to points of natural concentrations of eels, dynamic hydraulics of tailrace areas, and presence of significant competing flows from turbine outfalls or spill. As a result, some constructed eel passes are sited poorly and may pass only a fraction of the number of eels attempting to pass the barrier. When sited and constructed appropriately, however, eel passes

  17. Animal Behavior: Electric Eels Amp Up for an Easy Meal.

    PubMed

    Carlson, Bruce A

    2015-11-16

    The high voltage discharge generated by electric eels is a powerful predatory weapon. A new study shows that eels exploit basic physics to increase the voltage delivered to prey, inducing muscle fatigue that turns challenging prey items into easy targets. PMID:26583894

  18. Deep-ocean origin of the freshwater eels.

    PubMed

    Inoue, Jun G; Miya, Masaki; Miller, Michael J; Sado, Tetsuya; Hanel, Reinhold; Hatooka, Kiyotaka; Aoyama, Jun; Minegishi, Yuki; Nishida, Mutsumi; Tsukamoto, Katsumi

    2010-06-23

    Of more than 800 species of eels of the order Anguilliformes, only freshwater eels (genus Anguilla with 16 species plus three subspecies) spend most of their lives in freshwater during their catadromous life cycle. Nevertheless, because their spawning areas are located offshore in the open ocean, they migrate back to their specific breeding places in the ocean, often located thousands of kilometres away. The evolutionary origin of such enigmatic behaviour, however, remains elusive because of the uncertain phylogenetic position of freshwater eels within the principally marine anguilliforms. Here, we show strong evidence for a deep oceanic origin of the freshwater eels, based on the phylogenetic analysis of whole mitochondrial genome sequences from 56 species representing all of the 19 anguilliform families. The freshwater eels occupy an apical position within the anguilliforms, forming a highly supported monophyletic group with various oceanic midwater eel species. Moreover, reconstruction of the growth habitats on the resulting tree unequivocally indicates an origination of the freshwater eels from the midwater of the deep ocean. This shows significant concordance with the recent collection of mature adults of the Japanese eel in the upper midwater of the Pacific, suggesting that they have retained their evolutionary origin as a behavioural trait in their spawning areas. PMID:20053660

  19. Enteric neuroplasticity in seawater-adapted European eel (Anguilla anguilla).

    PubMed

    Sorteni, C; Clavenzani, P; De Giorgio, R; Portnoy, O; Sirri, R; Mordenti, O; Di Biase, A; Parmeggiani, A; Menconi, V; Chiocchetti, R

    2014-02-01

    European eels live most of their lives in freshwater until spawning migration to the Sargasso Sea. During seawater adaptation, eels modify their physiology, and their digestive system adapts to the new environment, drinking salt water to compensate for the continuous water loss. In that period, eels stop feeding until spawning. Thus, the eel represents a unique model to understand the adaptive changes of the enteric nervous system (ENS) to modified salinity and starvation. To this purpose, we assessed and compared the enteric neuronal density in the cranial portion of the intestine of freshwater eels (control), lagoon eels captured in brackish water before their migration to the Sargasso Sea (T0), and starved seawater eels hormonally induced to sexual maturity (T18; 18 weeks of starvation and treatment with standardized carp pituitary extract). Furthermore, we analyzed the modification of intestinal neuronal density of hormonally untreated eels during prolonged starvation (10 weeks) in seawater and freshwater. The density of myenteric (MP) and submucosal plexus (SMP) HuC/D-immunoreactive (Hu-IR) neurons was assessed in wholemount preparations and cryosections. The number of MP and SMP HuC/D-IR neurons progressively increased from the freshwater to the salty water habitat (control > T0 > T18; P < 0.05). Compared with freshwater eels, the number of MP and SMP HuC/D-IR neurons significantly increased (P < 0.05) in the intestine of starved untreated salt water eels. In conclusion, high salinity evokes enteric neuroplasticity as indicated by the increasing number of HuC/D-IR MP and SMP neurons, a mechanism likely contributing to maintaining the body homeostasis of this fish in extreme conditions. PMID:24433383

  20. Is feeding behaviour related to glass eel propensity to migrate?

    NASA Astrophysics Data System (ADS)

    Bureau du Colombier, Sarah; Lambert, Patrick; Bardonnet, Agnès

    2008-11-01

    Several studies have shown that eel diadromy is facultative and that migratory divergences may appear during glass eel estuarine migration. The origin of the differences in migratory behaviour among glass eels remains unclear but initial evidence supports the role of individual energetic and thyroidal status. Even if starvation is usually associated with glass eel migration, feeding does seem to occur in some glass eels. The aim of the present study was to investigate feeding behaviour and glass eel growth in relation to the propensity to migrate. Feeding rate and weight gain were higher in fish having a high propensity to migrate (M + fish) than in fish having a low propensity to migrate (M - fish) in fed glass eels, whereas no clear difference in the variation in body weight was observed among unfed fish (controls). M - fish initially had lower percent dry weight than M + fish, which suggests a link between appetite, propensity to migrate, and energy content. We discuss the role played by endocrine signals on these processes. In fish, thyroid hormones contribute to the control of growth and development. In addition, they play a role in flatfish and leptocephalus metamorphosis and appear to be involved in smolt and glass eel migratory behaviour. As such, they represent a good candidate which would promote the propensity to migrate as well as digestive system development. Their role in the hormonal control of food intake however remains vague. The large and sharp decline in glass eel abundances observed since the 1980s could partly be explained by changes in ocean productivity. If so, it could be accompanied by a decrease in glass eel energy stores. The ability to resume feeding in the course of the estuarine crossing would then represent a serious advantage to maintain energy levels compatible with migration.

  1. PAH metabolites, GST and EROD in European eel (Anguilla anguilla) as possible indicators for eel habitat quality in German rivers.

    PubMed

    Kammann, Ulrike; Brinkmann, Markus; Freese, Marko; Pohlmann, Jan-Dag; Stoffels, Sandra; Hollert, Henner; Hanel, Reinhold

    2014-02-01

    The stock of the European eel (Anguilla anguilla L.) continues to decline and has reached a new minimum in 2011. Poor health status of the spawners due to organic contaminants is one of the possible causes for this dramatic situation. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants, which are rapidly metabolized in vertebrates. EROD (ethoxyresorufin-O-deethylase) and GST (glutathione-S-transferase) are two enzymes involved in PAH detoxification in fish. In this study, PAH metabolites as well as EROD and GST activity in a large, comprising dataset of more than 260 migratory and pre-migratory eels from five large German river basin districts were used to describe PAH exposure and its metabolism as possible indicators for the habitat quality for eels. Eel from the river Elbe appear to be moderately contaminated with PAH. Highest mean values of PAH metabolites were analysed in fish from the river Rhine. However, the results suggest that contaminants such as PAH are metabolized in the fish and may have contributed to EROD activity in eels caught from the Elbe estuary to 600 km upstream. Since the eel's onset of cessation of feeding is closely linked to maturation and migration, we propose bile pigments as new indicators contributing to identify the proportion of migratory eel, which is crucial information for eel management plans. We showed that PAH metabolites normalized to bile pigments as well as EROD could be used to describe the habitat quality and might be suitable parameters in search for suitable stocking habitats. PMID:24085514

  2. Complete Genome Sequences of Two Japanese Eel Endothelial Cell-Infecting Virus Strains Isolated in Japan.

    PubMed

    Naoi, Yuki; Okazaki, Sachiko; Katayama, Yukie; Omatsu, Tsutomu; Ono, Shin-Ichi; Mizutani, Tetsuya

    2015-01-01

    Japanese eel endothelial cell-infecting virus (JEECV) causes viral endothelial cell necrosis of eel (VECNE), resulting in severe economic losses in eel aquaculture in Japan. Here, we report the complete genome sequences of two new JEECV strains isolated from farmed Japanese eels. PMID:26564031

  3. Do we protect freshwater eels or do we drive them to extinction?

    PubMed

    Arai, Takaomi

    2014-01-01

    Freshwater eels are important animals because they have a unique catadromous life history and are used as food resources. European, American and Japanese eel populations now are considered to be outside the safe biological limits and are seriously threatened with extinction. Therefore, the European eel was recently categorised as critically endangered by the European Union and the United Nations. One of the reasons for the drastic decline in eel populations is overfishing, which has caused a high demand for eel aquaculture; eel aquaculture completely depends on wild juveniles, and in contrast to animals, artificial propagation has not yet succeeded for the eels. Therefore, commercial eel industries are now considering tropical eels as possible replacement for European and Japanese eels to compensate for declining stocks. In this study, I attempt to examine the present status of the biology and stock of tropical eels. However, useful scientific research and information on the biology and stock assessments of tropical eels are lacking, a situation quite different from that for other temperate freshwater eels, which have been well studied for several decades with trends and recruitment patterns being on record. Nevertheless, the present tropical eel catch has been reported as being less than half that of 20 years ago. The present trends in eel stocks and utilization for human consumption suggest that all eel populations will decline to numbers that fall outside safe biological limits and will be seriously threatened with extinction without protection and conservation from strict enforcement of local and international laws. PMID:25279325

  4. Triacylglyceride physiology in the short-finned eel, Anguilla australis--the effects of androgen.

    PubMed

    Damsteegt, Erin L; Ozaki, Yuichi; McCormick, Sally P A; Lokman, P Mark

    2016-03-01

    The importance of androgens (especially 11-ketotestosterone) during previtellogenesis in eels is well established. In wild pubertal migrants, circulating 11-ketotestosterone levels correlate with a number of morphological and molecular changes. Here, we test the prediction that this correlation represents a causal relationship by artificially raising the levels of circulating 11-ketotestosterone in prepubertal nonmigratory female and pubertal, migratory male short-finned eels (Anguilla australis) using sustained-release hormone implants. In females, increases in hepatosomatic index and transcript copy numbers of hepatic apolipoprotein B and microsomal triacylglyceride transfer protein indicated increased repackaging of endogenously sourced triacylglycerides. These changes in liver measures were reflected in increased concentrations of serum triacylglycerides. However, despite a small increase in gonadosomatic index, ovarian lipoprotein receptor transcript abundances were not affected by 11-ketotestosterone. Interestingly, no such changes in hepatic gene expression were detected in a dose-response experiment using males. We propose that the androgens are inducing the observed changes in previtellogenic females, although it remains unclear to what extent these effects are direct or indirect. PMID:26764051

  5. Genomics in eels--towards aquaculture and biology.

    PubMed

    Minegishi, Yuki; Henkel, Christiaan V; Dirks, Ron P; van den Thillart, Guido E E J M

    2012-10-01

    Freshwater eels (genus Anguilla), especially the species inhabiting the temperate areas such as the European, American and Japanese eels, are important aquaculture species. Although artificial reproduction has been attempted since the 1930s and large numbers of studies have been conducted, it has not yet fully succeeded. Problems in eel artificial breeding are highly diverse, for instance, lack of basic information about reproduction in nature, no appropriate food for larvae, high mortality, and high individual variation in adults in response to maturation induction. Over the last decade, genomic data have been obtained for a variety of aquatic organisms. Recent technological advances in sequencing and computation now enable the accumulation of genomic information even for non-model species. The draft genome of the European eel Anguilla anguilla has been recently determined using Illumina technology and transcriptomic data based on next generation sequencing have been emerging. Extensive genomic information will facilitate many aspects of the artificial reproduction of eels. Here, we review the progress in genome-wide studies of eels, including additional analysis of the European eel genome data, and discuss future directions and implications of genomic data for aquaculture. PMID:22527267

  6. Relative antidipsogenic potencies of six homologous natriuretic peptides in eels.

    PubMed

    Miyanishi, Hiroshi; Nobata, Shigenori; Takei, Yoshio

    2011-10-01

    Atrial natriuretic peptide (ANP) exhibits a potent antidipsogenic effect in seawater (SW) eels to limit excess Na(+) uptake, thereby effectively promoting SW adaptation. Recently, cardiac ANP, BNP and VNP and brain CNP1, 3 and 4, have been identified in eels. We examined the antidipsogenic effect of all homologous NPs using conscious, cannulated eels in both FW and SW together with parameters that affect drinking. A dose-response study (0.01-1 nmol/kg) in SW eels showed the relative potency of the antidipsogenic effect was in the order ANP ≥ VNP > BNP = CNP3 > CNP1 ≥ CNP4, while the order was ANP = VNP = BNP > CNP3 = CNP1 = CNP4 for the vasodepressor effect. The minimum effective dose of ANP for the antidipsogenic effect is much lower than that in mammals. ANP, BNP and VNP at 0.3 nmol/kg decreased drinking, plasma Na(+) concentration and aortic pressure and increased hematocrit in SW eels. The cardiac NPs induced similar changes in drinking, aortic pressure and hematocrit in FW eels, but aside from BNP no change in plasma Na(+) concentration. CNPs had no effect on drinking, plasma Na(+) concentration and hematocrit but induced mild hypotension in both FW and SW eels, except for CNP3 that inhibited drinking in SW eels. These results show that ANP, BNP and VNP are potent antidipsogenic hormones in eels in spite of other regulatory factors working to induce drinking, and that CNPs are without effects on drinking except for the ancestor of the cardiac NPs, CNP3. PMID:21967218

  7. Antidiuretic Effect of Eel ANP Infused at Physiological Doses in Conscious, Seawater-Adapted Eels, Anguilla japonica.

    PubMed

    Takei, Y; Kaiya, H

    1998-06-01

    Atrial natriuretic peptide (ANP) is known as a potent natriuretic/diuretic hormone in vertebrates. However, eel ANP infused at doses that did not alter arterial blood pressure (0.3-3.0 pmol/kg/min) decreased urine volume and increased urinary Na concentration in seawater (SW)-adapted eels but not in freshwater (FW)-adapted eels. The renal effects were dose-dependent and disappeared after infusate was switched back to a vehicle (0.9% NaCl). Urinary Na excretion (volume x Na concentration) did not change during ANP infusion. ANP infusion increased plasma ANP concentration, but the increase at the highest dose was still within those observed endogenously after injection of hypertonic saline. Urinary Mg and Ca concentrations increased during ANP infusion in SW eels, but urinary Ca excretion decreased in FW eels. Plasma Na concentration profoundly decreased during ANP infusion only in SW eels, suggesting that ANP stimulates Na extrusion via non-renal routes. These results indicate that ANP is a hormone which specifically extrudes Na ions and thereby promotes SW adaptation in the eel. This is in sharp contrast with mammals where ANP is a volume regulating hormone that extrudes both Na and water. PMID:18466004

  8. Electron Energy-Loss Spectroscopy (EELS)Calculation in Finite-Difference Time-Domain (FDTD) Package: EELS-FDTD

    NASA Astrophysics Data System (ADS)

    Large, Nicolas; Cao, Yang; Manjavacas, Alejandro; Nordlander, Peter

    2015-03-01

    Electron energy-loss spectroscopy (EELS) is a unique tool that is extensively used to investigate the plasmonic response of metallic nanostructures since the early works in the '50s. To be able to interpret and theoretically investigate EELS results, a myriad of different numerical techniques have been developed for EELS simulations (BEM, DDA, FEM, GDTD, Green dyadic functions). Although these techniques are able to predict and reproduce experimental results, they possess significant drawbacks and are often limited to highly symmetrical geometries, non-penetrating trajectories, small nanostructures, and free standing nanostructures. We present here a novel approach for EELS calculations using the Finite-difference time-domain (FDTD) method: EELS-FDTD. We benchmark our approach by direct comparison with results from the well-established boundary element method (BEM) and published experimental results. In particular, we compute EELS spectra for spherical nanoparticles, nanoparticle dimers, nanodisks supported by various substrates, and gold bowtie antennas on a silicon nitride substrate. Our EELS-FDTD implementation can be easily extended to more complex geometries and configurations and can be directly implemented within other numerical methods. Work funded by the Welch Foundation (C-1222, L-C-004), and the NSF (CNS-0821727, OCI-0959097).

  9. Oceanic spawning migration of the European eel (Anguilla anguilla).

    PubMed

    Aarestrup, Kim; Okland, Finn; Hansen, Michael M; Righton, David; Gargan, Patrik; Castonguay, Martin; Bernatchez, Louis; Howey, Paul; Sparholt, Henrik; Pedersen, Michael I; McKinley, Robert S

    2009-09-25

    European eels (Anguilla anguilla) undertake a approximately 5000-kilometer (km) spawning migration from Europe to the Sargasso Sea. The larvae are transported back to European waters by the Gulf Stream and North Atlantic Drift. However, details of the spawning migration remain unknown because tracking eels in the Atlantic Ocean has, so far, eluded study. Recent advances in satellite tracking enable investigation of migratory behavior of large ocean-dwelling animals. However, sizes of available tags have precluded tracking smaller animals like European eels. Here, we present information about the swimming direction, depth, and migratory behavior of European eels during spawning migration, based on a miniaturized pop-up satellite archival transmitter. Although the tagging experiment fell short of revealing the full migration to the Sargasso Sea, the data covered the first 1300 km and provided unique insights. PMID:19779192

  10. 8. EEL RIVER SOUTH FORK BRIDGE, OLD HIGHWAY 101. NORTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. EEL RIVER SOUTH FORK BRIDGE, OLD HIGHWAY 101. NORTH OF LEGGETT, HUMBOLDT COUNTY, CALIFORNIA. LOOKING N. - Redwood National & State Parks Roads, California coast from Crescent City to Trinidad, Crescent City, Del Norte County, CA

  11. 9. EEL RIVER SOUTH FORK BRIDGE, OLD HIGHWAY 101. NORTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. EEL RIVER SOUTH FORK BRIDGE, OLD HIGHWAY 101. NORTH OF LEGGETT, HUMBOLDT COUNTY, CALIFORNIA. LOOKING W. - Redwood National & State Parks Roads, California coast from Crescent City to Trinidad, Crescent City, Del Norte County, CA

  12. Temperature modulates testis steroidogenesis in European eel.

    PubMed

    Peñaranda, David S; Morini, Marina; Tveiten, Helge; Vílchez, M Carmen; Gallego, Victor; Dirks, Ron P; van den Thillart, Guido E E J M; Pérez, Luz; Asturiano, Juan F

    2016-07-01

    This study evaluates the effects of temperature on hCG-induced spermatogenesis in European eel (Anguilla anguilla), subjected to three thermal regimes: T10: 10°C (first 4weeks), 15°C (next 3weeks) and 20°C (last 6weeks); T15: 15°C (first 4weeks) and 20°C (last 9weeks); and T20: constant 20°C for the duration of the experiment. At 10°C, maturation stopped in the A spermatogonial stage (SPG1), and no further maturation was observed until the temperature was ≥15°C. With the aim of explaining these results, the influence of temperature on steroidogenic enzyme gene expression and steroid synthesis was tested. The initial synthesis of androgens (T and 11-KT) increased at SPG1, and was not influenced by temperature. Likewise, the gene expression of the steroidogenic enzymes linked to androgen synthesis (aacyp11a1, aacyp17-I and aa11βHSD) also increased at SPG1. In contrast, no correlation was seen between the increase in E2 and the aacyp19a1 gene expression peak in the testes, with E2 increasing as a consequence of the seawater acclimation carried out before hormonal treatment, and peaking the aacyp19a1 gene expression at B spermatogonial stage (SPG2). Aacyp21 gene expression was also higher at SPG2, and this stage was only reached when the rearing temperature was ≥15°C. In conclusion, androgen synthesis is not dependent on temperature, but further maturation requires higher temperatures in order to induce a change in the steroidogenic pathway towards estrogen and progestin synthesis. This study demonstrates that temperature plays a crucial role in European eel maturation, even perhaps controlling gonad development during the reproductive migration. PMID:27013359

  13. Primitive duplicate Hox clusters in the European eel's genome.

    PubMed

    Henkel, Christiaan V; Burgerhout, Erik; de Wijze, Daniëlle L; Dirks, Ron P; Minegishi, Yuki; Jansen, Hans J; Spaink, Herman P; Dufour, Sylvie; Weltzien, Finn-Arne; Tsukamoto, Katsumi; van den Thillart, Guido E E J M

    2012-01-01

    The enigmatic life cycle and elongated body of the European eel (Anguilla anguilla L., 1758) have long motivated scientific enquiry. Recently, eel research has gained in urgency, as the population has dwindled to the point of critical endangerment. We have assembled a draft genome in order to facilitate advances in all provinces of eel biology. Here, we use the genome to investigate the eel's complement of the Hox developmental transcription factors. We show that unlike any other teleost fish, the eel retains fully populated, duplicate Hox clusters, which originated at the teleost-specific genome duplication. Using mRNA-sequencing and in situ hybridizations, we demonstrate that all copies are expressed in early embryos. Theories of vertebrate evolution predict that the retention of functional, duplicate Hox genes can give rise to additional developmental complexity, which is not immediately apparent in the adult. However, the key morphological innovation elsewhere in the eel's life history coincides with the evolutionary origin of its Hox repertoire. PMID:22384188

  14. Diet-induced phenotypic plasticity in European eel (Anguilla anguilla).

    PubMed

    De Meyer, Jens; Christiaens, Joachim; Adriaens, Dominique

    2016-02-01

    Two phenotypes are present within the European eel population: broad-heads and narrow-heads. The expression of these phenotypes has been linked to several factors, such as diet and differential growth. The exact factors causing this dimorphism, however, are still unknown. In this study, we performed a feeding experiment on glass eels from the moment they start to feed. Eels were either fed a hard diet, which required biting and spinning behavior, or a soft diet, which required suction feeding. We found that the hard feeders develop a broader head and a larger adductor mandibulae region than eels that were fed a soft diet, implying that the hard feeders are capable of larger bite forces. Next to this, soft feeders develop a sharper and narrower head, which could reduce hydrodynamic drag, allowing more rapid strikes towards their prey. Both phenotypes were found in a control group, which were given a combination of both diets. These phenotypes were, however, not as extreme as the hard or the soft feeding group, indicating that some specimens are more likely to consume hard prey and others soft prey, but that they do not selectively eat one of both diets. In conclusion, we found that diet is a major factor influencing head shape in European eel and this ability to specialize in feeding on hard or soft prey could decrease intra-specific competition in European eel populations. PMID:26847560

  15. Eel River margin source-to-sink sediment budgets: revisited

    USGS Publications Warehouse

    Warrick, Jonathan A.

    2014-01-01

    The Eel River coastal margin has been used as a representative source-to-sink sediment dispersal system owing to its steep, high-sediment yield river and the formation of sedimentary strata on its continental shelf. One finding of previous studies is that the adjacent continental shelf retains only ~25% of the Eel River fine-grained sediment (less than 63 μm) discharged over time scales of both individual floods and the 20th century, thus suggesting that the Eel shelf trapping-efficiency is uniquely lower than other similar systems. Here I provide data and analyses showing that sediment discharge relationships in the Eel River have varied strongly with time and include substantial decreases in suspended-sediment concentrations during the latter 20th century. Including these trends in margin-wide sediment budgets, I show that previous Eel River sediment discharge rates were overestimated by a factor of two. Thus, revised sediment budgets shown here reveal that the Eel shelf retained ~50% of the discharged river fine-grained suspended sediment during intensively sampled events of 1995–97 and over the 20th century. In light of this, hypotheses about high rates of sediment export away from the primary shelf depocenter should be reevaluated.

  16. Genetic evidence against panmixia in the European eel.

    PubMed

    Wirth, T; Bernatchez, L

    2001-02-22

    The panmixia hypothesis--that all European eel (Anguilla anguilla) migrate to the Sargasso Sea for reproduction and comprise a single, randomly mating population--is widely accepted. If true, then this peculiar life history strategy would directly impact the population genetics of this species, and eels from European and north African rivers should belong to the same breeding population through the random dispersal of larvae. To date, the panmixia hypothesis has remained unchallenged: genetic studies realized on eel's mitochondrial DNA failed to detect any genetic structure; and a similar lack of structure was found using allozymes, with the exception of clinal variation imposed by selection. Here we have used highly polymorphic genetic markers that provide better resolution to investigate genetic structure in European eel. Analysis of seven microsatellite loci among 13 samples from the north Atlantic, the Baltic Sea and the Mediterranean Sea basins reveals that there is global genetic differentiation. Moreover, pairwise Cavalli-Sforza and Edwards chord distances correlate significantly with coastal geographical distance. This pattern of genetic structure implies non-random mating and restricted gene flow among eels from different sampled locations, which therefore refute the hypothesis of panmixia. Consequently, the reproductive biology of European eel must be reconsidered. PMID:11234011

  17. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na[sub 2]O added as NAOH instead of Na[sub 2]CO[sub 3] to avoid severe foaming due to CO[sub 2] evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  18. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na{sub 2}O added as NAOH instead of Na{sub 2}CO{sub 3} to avoid severe foaming due to CO{sub 2} evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  19. A comparison of metal concentrations in the tissues of yellow American eel (Anguilla rostrata) and European eel (Anguilla anguilla).

    PubMed

    Pannetier, Pauline; Caron, Antoine; Campbell, Peter G C; Pierron, Fabien; Baudrimont, Magalie; Couture, Patrice

    2016-11-01

    Historically abundant and widespread, populations of Atlantic eels have suffered a sharp decline in recent decades, in the ranges 40-80% and 90-99% for American and European eels, respectively. As a result, American eels are now classified as threatened, whereas European eels are considered to be in critical danger of extinction. Several causes have been identified as likely contributors of this decline, including overfishing, obstacles to migration (hydroelectric dams), climate change and habitat contamination. In the context of a larger project investigating the role of organic and inorganic contaminants in this decline, in this study, we measured the liver, kidney and muscle concentrations of essential (Cu, Se and Zn) and non-essential (Ag, As, Cd, Cr, Hg, Ni and Pb) metals in eels sampled at four sites in the South-West of France and four sites in Eastern Canada varying in contamination. Tissue concentrations of Cd, Hg and Se increased with fish size and age. Tissue metal concentrations generally reflected the contamination of their sampling sites. This was the case for Ag, As, Cd, Cu, Hg, Pb and Se. Comparison of tissue concentrations of these metals with the toxicological literature suggests that all of them except As could pose a risk to the health of eels from the most contaminated sites. In particular, European eels may be particularly at risk of Cd and Pb toxicity. Globally, our study suggests that a substantial accumulation of inorganic contaminants in the tissues of both eel species at sites contaminated by historical anthropogenic inputs may play a role in their decline. PMID:27395077

  20. Excitation dependent Fano-like interference effects in plasmonic silver nanorods

    NASA Astrophysics Data System (ADS)

    Collins, Sean M.; Nicoletti, Olivia; Rossouw, David; Ostasevicius, Tomas; Midgley, Paul A.

    2014-10-01

    Surface plasmon resonances in metal nanoparticles are an emerging technology platform for nano-optics applications from sensing to solar energy conversion. The electromagnetic near field associated with these resonances arises from modes determined by the shape, size, and composition of the metal nanoparticle. When coupled in the near field, multiple resonant modes can interact to give rise to interference effects offering fine control of both the spectral response and spatial distribution of fields near the particle. Here, we present an examination of experimental electron energy loss spectroscopy (EELS) of silver nanorod monomer surface plasmon modes and present an explanation of observed spatial amplitude modulation of the Fabry-Pérot resonance modes of these silver nanorods using electrodynamics simulations. For these simulations, we identify differences in spectral peak symmetry in light scattering and electron spectroscopies (EELS and cathodoluminescence) and analyze the distinct near-field responses of silver nanorods to plane-wave light and electron beam excitation in terms of a coupled oscillator model. Effects of properties of the material and the incident field are evaluated, and the spatially resolved EELS signals are shown to provide a signature for assessing Fano-like interference effects in silver nanorods. These findings outline key considerations and challenges for interpreting electron microscopy data on plasmonic nanoparticles for understanding nanoscale optics and for characterization and design of photonic devices.

  1. Trace metals in Japanese eel Anguilla japonica in relation to ecological migratory types and growth stages

    NASA Astrophysics Data System (ADS)

    Le, Dung Quang; Chino, Naoko; Shirai, Kotaro; Arai, Takaomi

    2010-04-01

    In order to understand the metal concentrations in Japanese eel Anguilla japonica, nine elements were analyzed in the livers of different migratory types of eels collected from Tokushima region (south Japan). Migratory types were defined by examining the Sr:Ca ratio in otoliths. The results showed that there were significant differences in V, Cr, Cd, and Pb concentrations among the migratory types. Mature-sea-eels show a higher risk of metal accumulation than other migratory types of eels, and the concentrations of Mn, Cu, and Zn in mature eels were significantly higher than those in immature eels. The study suggests that the eel liver is a valuable bioindicator for trace metals; however, when using the eel as a bioindicator to reveal the pollutants in aquatic systems, life history analysis should be carried out for accurate interpretation of the results.

  2. Phylogeny of moray eels (Anguilliformes: Muraenidae), with a revised classification of true eels (Teleostei: Elopomorpha: Anguilliformes).

    PubMed

    Tang, Kevin L; Fielitz, Christopher

    2013-02-01

    The family Muraenidae is one of the largest and most recognizable eel groups. Moray eels are key components of marine ecosystems but their relationships remain poorly understood. The phylogenetic relationships of the morays are examined herein using mitochondrial 12S and 16S sequence data, totaling 1673 bp for 139 taxa. The results of our analyses found support for a monophyletic family Muraenidae that is part of a monophyletic suborder Muraenoidei, which is revised to include the anguilliform families Heterenchelyidae and Myrocongridae, and to exclude the family Chlopsidae. The muraenids form two monophyletic subfamilies, Muraeninae and Uropterygiinae. Of the genera that had multiple species included for analysis, only the type genus of the family, Muraena, is found to be monophyletic. In the subfamily Uropterygiinae, Uropterygius is not recovered as a monophyletic genus. In the subfamily Muraeninae, the species-rich piscivorous genera, Enchelycore and Gymnothorax, and the durophagous genus, Echidna, are demonstrably not monophyletic. The monotypic Gymnomuraena is the sister group to all other muraenine species. The relationships within Muraenidae require much additional study and its genera remain in urgent need of revision. The order Anguilliformes is revised herein to include four suborders: Anguilloidei, Congroidei, Muraenoidei, and Synaphobranchoidei. All four families of the order Saccopharyngiformes are nested within Anguilliformes, recovered as part of a clade that includes Anguillidae; the saccopharyngiform families are referred to the suborder Anguilloidei sensu novum. PMID:22967094

  3. Catadromous eels continue to be slippery research subjects.

    PubMed

    Avise, John C

    2011-04-01

    As adults, Atlantic eels (Anguilla rostrata in the Americas and Anguilla anguilla in Europe) are tubular slime-covered fish that spend most of their catadromous life-cycle in coastal environs before swimming far out to sea to reproduce, as part of an intergenerational migratory circuit that provides an interesting reversal of the pattern displayed by adult anadromous salmon that live mostly in the ocean but then migrate long distances to spawn in freshwater streams. Earlier genetic findings on Atlantic eels involved specimens collected across their broad continental ranges and generally indicated that conspecifics probably engage in panmictic or quasi-panmictic spawning,from which arise leaf-shaped leptocephaus larvae that then disperse back to coastal locations more or less at random with respect to the widespread geographical origins of the parental genes they carry. In this issue, Alset al. (2011) add exciting information about this peculiar life-history pattern of catadromous Atlantic eels by extending the genetic analyses to eel larvae collected from the Sargasso Sea, the oceanic area where both species spawn. Results help to confirm standard textbook wisdom that these catadromous eels are nearly unique in the biological world by having both broad geographical distributions and yet displaying intraspecific near panmixia. PMID:21544942

  4. Introgressive hybridization and latitudinal admixture clines in North Atlantic eels

    PubMed Central

    2014-01-01

    Background Hybridization, the interbreeding of diagnosably divergent species, is a major focus in evolutionary studies. Eels, both from North America and Europe migrate through the Atlantic to mate in a vast, overlapping area in the Sargasso Sea. Due to the lack of direct observation, it is unknown how these species remain reproductively isolated. The detection of inter-species hybrids in Iceland suggests on-going gene flow, but few studies to date have addressed the influence of introgression on genetic differentiation in North Atlantic eels. Results Here, we show that while mitochondrial lineages remain completely distinct on both sides of the Atlantic, limited hybridization is detectable with nuclear DNA markers. The nuclear hybridization signal peaks in the northern areas and decreases towards the southern range limits on both continents according to Bayesian assignment analyses. By simulating increasing proportions of both F1 hybrids and admixed individuals from the southern to the northern-most locations, we were able to generate highly significant isolation-by-distance patterns in both cases, reminiscent of previously published data for the European eel. Finally, fitting an isolation-with-migration model to our data supports the hypothesis of recent asymmetric introgression and refutes the alternative hypothesis of ancient polymorphism. Conclusions Fluctuating degrees of introgressive hybridization between Atlantic eel species are sufficient to explain temporally varying correlations of geographic and genetic distances reported for populations of the European eel. PMID:24674242

  5. First Production of Larvae Using Cryopreserved Sperm: Effects of Preservation Temperature and Cryopreservation on European Eel Sperm Fertilization Capacity.

    PubMed

    Asturiano, J F; Sørensen, S R; Pérez, L; Lauesen, P; Tomkiewicz, J

    2016-08-01

    Sperm cryopreservation is a useful tool in captive fish reproduction management, that is to synchronize gamete production, especially in the case of species as the European eel, where the time of female spawning readiness is unpredictable. Several protocols to cryopreserve sperm of this species have been described, but until recently fertilization trials were not feasible. This study evaluated the effect of cold storage of diluted sperm prior to fertilizations and tested whether a previously defined protocol for European eel sperm cryopreservation can be successfully applied in fertilization trials to produce viable offspring. In our experiment, the sperm motility was evaluated after the extraction and the best samples were selected and pooled. Until stripping of eggs and fertilization, diluted sperm samples were maintained at either 4 or 20°C, or cryopreserved, following existing protocols. Fertilization of two egg batches was attempted. Diluted sperm caused a similar percentage of fertilized eggs and a similar number of embryos and larvae, independently of storage temperature (4 or 20°C). The cryopreserved sperm resulted in a lower percentage of fertilized eggs, but embryos developed and a few larvae ('cryolarvae') were obtained 55 h after fertilization in one of the two egg batches. This result evidences that the tested cryopreservation protocol is applicable for eel reproduction management, although improvements will be required to enhance fertilization success. PMID:27189043

  6. Hepatic receptors for homologous growth hormone in the eel

    SciTech Connect

    Hirano, T. )

    1991-03-01

    The specific binding of 125I-labeled eel growth hormone (eGH) to liver membranes of the eel was examined. The specific binding to the 10,000g pellet was greater than that to the 600g pellet. The specific binding was linear up to about 100 mg fresh tissue, and was saturable with increasing amounts of membrane. The specific binding was pH-, temperature-, and time-dependent, with the optimum pH at 7.4, and greater specific binding was obtained at 15 and 25 degrees than at 35 degrees. Scatchard analysis of liver binding gave an association constant of 1.1 x 10(9) M-1 and a capacity of 105 fmol/mg protein. The receptor preparation was highly specific for GHs. Natural and recombinant eel GHs as well as recombinant salmon GH competed equally with 125I-eGH for the receptor sites of the 10,000g liver membrane. Ovine GH was more potent in displacing the labeled eGH than the homologous eel hormone. Tilapia GH and ovine prolactin (PRL) were needed in greater amounts (40 times) than eGH to displace the labeled eGH. Salmon and tilapia PRLs were still less potent (500 times) than eGH. There was no displacement with eel PRL. No significant change in the specific binding was seen 1 week after hypophysectomy, whereas injection of eGH into the hypophysectomized eel caused a significant reduction after 24 hr. The binding to the membrane fractions from gills, kidney, muscle, intestine, and brain was low and exclusively nonspecific, indicating the presence of specific GH receptors predominantly in the liver.

  7. Immunolocalisation of aquaporin 3 in the gill and the gastrointestinal tract of the European eel Anguilla anguilla (L.).

    PubMed

    Lignot, Jean-H; Cutler, Christopher P; Hazon, Neil; Cramb, Gordon

    2002-09-01

    The expression of a putative water channel protein, aquaporin 3 (AQP-3), has been localised within branchial and intestinal tissues from the 'silver' life stage of the European eel Anguilla anguilla, using a specific polyclonal antibody directed against the C-terminal of the amino acid sequence. Western blots using the AQP-3 antiserum identified the presence of a major immunoreactive protein of 24 kDa in extracts of gills from both freshwater (FW) and 3 week seawater (SW)-acclimated eels. SW acclimation induced a 65 % reduction in AQP-3 protein abundance in the gill extracts. AQP-3 immunoreactivity was apparent throughout the branchial epithelium from both FW and SW-acclimated fish, but especially so within the chloride cells, which also stained heavily with specific antisera for the beta-subunit of the Na, K-ATPase. AQP-3 immunoreactivity not only colocalised with Na, K-ATPase within the basolateral tubular network but also stained the apical regions of the chloride cell where Na, K-ATPase was absent. Although there were no obvious differences in expression between the chloride cells of FW and SW-acclimated fish, considerably higher intensities of immunoreactivity were apparent near the periphery of the non-chloride cells of FW fish, especially within cells forming the base of the primary filaments and the branchial arch. AQP-3 immunoreactivity was also detected in intra-epithelial macrophage-like cells within the intestine of FW and SW-acclimated eels and in the mucous cells of the rectal epithelium of SW-acclimated fish. These results suggest that AQP-3 may play an important functional role in osmoregulation the teleostean gill but is unlikely to be responsible for the increases in intestinal water absorption that occur following SW acclimation. PMID:12151371

  8. Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels.

    PubMed

    Munk, Peter; Hansen, Michael M; Maes, Gregory E; Nielsen, Torkel G; Castonguay, Martin; Riemann, Lasse; Sparholt, Henrik; Als, Thomas D; Aarestrup, Kim; Andersen, Nikolaj G; Bachler, Mirjam

    2010-12-01

    Anguillid freshwater eels show remarkable life histories. In the Atlantic, the European eel (Anguilla anguilla) and American eel (Anguilla rostrata) undertake extensive migrations to spawn in the oceanic Sargasso Sea, and subsequently the offspring drift to foraging areas in Europe and North America, first as leaf-like leptocephali larvae that later metamorphose into glass eels. Since recruitment of European and American glass eels has declined drastically during past decades, there is a strong demand for further understanding of the early, oceanic phase of their life cycle. Consequently, during a field expedition to the eel spawning sites in the Sargasso Sea, we carried out a wide range of dedicated bio-physical studies across areas of eel larval distribution. Our findings suggest a key role of oceanic frontal processes, retaining eel larvae within a zone of enhanced feeding conditions and steering their drift. The majority of the more westerly distributed American eel larvae are likely to follow a westerly/northerly drift route entrained in the Antilles/Florida Currents. European eel larvae are generally believed to initially follow the same route, but their more easterly distribution close to the eastward flowing Subtropical Counter Current indicates that these larvae could follow a shorter, eastward route towards the Azores and Europe. The findings emphasize the significance of oceanic physical-biological linkages in the life-cycle completion of Atlantic eels. PMID:20573625

  9. Silver cyanide

    Integrated Risk Information System (IRIS)

    Silver cyanide ; CASRN 506 - 64 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  10. Toxic textile dyes accumulate in wild European eel Anguilla anguilla.

    PubMed

    Belpaire, Claude; Reyns, Tim; Geeraerts, Caroline; Van Loco, Joris

    2015-11-01

    Dyes are used to stain inks, paints, textile, paper, leather and household products. They are omnipresent, some are toxic and may threaten our environment, especially aquatic ecosystems. The presence of residues of sixteen dyes (triarylmethanes, xanthenes, phenothiazines and phenoxazines) and their metabolites was analyzed in muscle tissue samples of individual yellow-phased European eels (Anguilla anguilla) from 91 locations in Belgian rivers, canals and lakes sampled between 2000 and 2009 using ultra performance liquid chromatography-tandem mass spectrometry. Eel was contaminated by dyes in 77% of the sites. Malachite Green, Crystal Violet and Brilliant Green were present in 25-58% of the samples. Dye occurrence was related to the distribution of textile and dye production industries. This field study is the first large-scale survey to document the occurrence of artificial dyes in wildlife. Considering the annual amounts of dyes produced worldwide and the unintentional spillage during their use, our observations warrant additional research in other parts of the world. The presence of these highly toxic dyes in the European eel may form an additional threat to this critically endangered species. The contaminated eels should be considered as not suitable for consumption. PMID:26291760

  11. EELS analysis of complex precipitates in PM 2000 steel

    NASA Astrophysics Data System (ADS)

    Klimenkov, M.; Möslang, A.; Lindau, R.

    2008-06-01

    Formation of different types of nanosized Al-containing oxide precipitates in an Fe-Cr-Al alloy (PM 2000) was studied by electron energy loss spectroscopy (EELS) using a transmission electron microscope (TEM). It was shown that Y{3}Al{5}O{12} (garnet) and YAlO{3} (perovskite) as well as γ -Al{2}O{3} and α -Al{2}O{3} precipitates can be distinguished by analysing the O-K energy loss near-edge structure (ELNES). The formation of interface-specific phases on Al{2}O{3}/YAlO{3}, Al{2}O{3}/matrix and Y{3}Al{5}O{12}/matrix interfaces was also investigated by specially resolved EELS analysis. Applicability and sensitivity of the EELS method in the study of steel precipitates were discussed. A sharp pre-peak or “pre-shoulder” in the O-K edge was observed and studied by means of spatially resolved EELS of oxide inclusions. The intense pre-peak was found to be caused by radiation damage induced by the electron beam of the Al hydroxide phase inside Al{2}O{3} inclusions. This phase formed due to the incorporation of hydrogen in the matrix during mechanical alloying in the hydrogen atmosphere. The “pre-shoulder” of the main O-K feature measured on the inclusion/matrix interface results from the formation of a thin Ti-O layer.

  12. A global viability assessment of the European eel.

    PubMed

    Bevacqua, Daniele; Melià, Paco; Gatto, Marino; De Leo, Giulio A

    2015-09-01

    The global European eel (Anguilla anguilla) stock is critically endangered according to the IUCN, and the European Commission has urged the development of conservation plans aimed to ensure its viability. However, the complex life cycle of this panmictic species, which reproduces in the open ocean but spends most of its prereproductive life in continental waters (thus embracing a huge geographic range and a variety of habitat types), makes it difficult to assess the long-term effectiveness of conservation measures. The interplay between local and global stressors raises intriguing cross-scale conservation challenges that require a comprehensive modelling approach to be addressed. We developed a full life cycle model of the global European eel stock, encompassing both the oceanic and the continental phases of eel's life, and explicitly allowing for spatial heterogeneity in vital rates, availability of suitable habitat and settlement potential via a metapopulation approach. We calibrated the model against a long-term time series of global European eel catches and used it to hindcast the dynamics of the stock in the past and project it over the 21st century under different management scenarios. Although our analysis relies on a number of inevitable simplifying assumptions and on data that may not embrace the whole range of variation in population dynamics at the small spatiotemporal scale, our hindcast is consistent with the general pattern of decline of the stock over recent decades. The results of our projections suggest that (i) habitat loss played a major role in the European eel decline; (ii) the viability of the global stock is at risk if appropriate protection measures are not implemented; (iii) the recovery of spawner escapement requires that fishing mortality is significantly reduced; and (iv) the recovery of recruitment might not be feasible if reproductive output is not enhanced. PMID:25965113

  13. Cloning, structure, and expression pattern of the P-450 aromatase gene in rice field eel (Monopterus albus).

    PubMed

    Yu, Ju-Hua; Tang, Yong-Kai; Li, Jian-Lin

    2008-06-01

    We report the cloning, tissue expression, and structural analysis of the aromatase gene in the rice field eel (Monopterus albus). The ovary-derived cDNA (1,802 bp) has a 49 bp 5'-untranslated region (UTR), a 202 bp 3'-UTR, and a 1,551 bp open-reading frame, which encodes a protein of 517 amino acid residues with a predicted molecular weight of 58.2 kDa. The amino acid sequence alignment suggests that the rice field eel ovarian P-450 aromatase shares 63-80% identity with that of other fish species, reduced to 59-60% with brain-derived aromatases of other fishes and to 50% with human placenta aromatases. Between the 5' and 3' untranslated terminal regions, the rice field eel CYP19 gene contained seven introns at the same sites as in medaka and human but lacked an intron between the I-helix and the aromatase-specific conserved region. All introns conformed to the GT/AG rule. Sequence analysis of the 1,065 bp upstream of the translation start site revealed that the transcription initiation site was 51 bp upstream from the translation start site. This region had one estrogen receptor recognition half site (nt -62), five copies of an SRY/iSRY binding motif, a C/EBP (CCAAT enhancer binding protein) binding site (nt -751), chicken ovalbumin upstream promoter-transcription factor (nt -986) and GATA-2 (nt -186, -249) recognition sequences, but no binding sequence for steroidogenic factor-1 and the cAMP response element binding protein activating transcription factor family. In females, levels of relative expression were, in descending order, hypothalamus, pituitary, forebrain, ovary, and liver. In males, P450arom was detected only in the pituitary and the liver, with half the expression found in females. In fry, the P450arom expression level increased during development and was significantly higher in the brain than in the gonad. PMID:18246459

  14. Dietary effects on fatty acid composition in muscle tissue of juvenile European eel, Anguilla anguilla (L.)

    NASA Astrophysics Data System (ADS)

    Prigge, Enno; Malzahn, Arne M.; Zumholz, Karsten; Hanel, Reinhold

    2012-03-01

    The role of intracontinental migration patterns of European eel ( Anguilla anguilla) receives more and more recognition in both ecological studies of the European eel and possible management measures, but small-scale patterns proved to be challenging to study. We experimentally investigated the suitability of fatty acid trophic markers to elucidate the utilization of feeding habitats. Eight groups of juvenile European eels were fed on eight different diets in a freshwater recirculation system at 20°C for 56 days. Three groups were fed on freshwater diets ( Rutilus rutilus, Chironomidae larvae, and Gammarus pulex) and four groups were reared on diets of a marine origin ( Clupea harengus, Crangon crangon, Mysis spec., and Euphausia superba) and one on commercial pellets used in eel aquaculture. Fatty acid composition (FAC) of diets differed significantly with habitat. FAC of eel muscle tissue seemed to be rather insensitive to fatty acids supplied with diet, but the general pattern of lower n3:n6 and EPA:ARA ratios in freshwater prey organisms could be traced in the respective eels. Multivariate statistics of the fatty acid composition of the eels resulted in two distinct groups representing freshwater and marine treatments. Results further indicate the capability of selectively restraining certain fatty acids in eel, as e.g. the n3:n6 ratio in all treatments was <4, regardless of dietary n3:n6. In future studies on wild eel, these measures can be used to elucidate the utilization of feeding habitats of individual European eel.

  15. An Optimized Biological Taser: Electric Eels Remotely Induce or Arrest Movement in Nearby Prey.

    PubMed

    Catania, Kenneth C

    2015-09-01

    Despite centuries of interest in electric eels, few studies have investigated the mechanism of the eel's attack. Here, I review and extend recent findings that show eel electric high-voltage discharges activate prey motor neuron efferents. This mechanism allows electric eels to remotely control their targets using two different strategies. When nearby prey have been detected, eels emit a high-voltage volley that causes whole-body tetanus in the target, freezing all voluntary movement and allowing the eel to capture the prey with a suction feeding strike. When hunting for cryptic prey, eels emit doublets and triplets, inducing whole-body twitch in prey, which in turn elicits an immediate eel attack with a full volley and suction feeding strike. Thus, by using their modified muscles (electrocytes) as amplifiers of their own motor efferents, eel's motor neurons remotely activate prey motor neurons to cause movement (twitch and escape) or immobilization (tetanus) facilitating prey detection and capture, respectively. These results explain reports that human movement is 'frozen' by eel discharges and shows the mechanism to resemble a law-enforcement Taser. PMID:26398438

  16. Habitat use of American eel (Anguilla rostrata) in a tributary of the Hudson River, New York

    USGS Publications Warehouse

    Johnson, James H.; Nack, Christopher C.

    2013-01-01

    American eel Anguilla rostrata populations are declining over much of their native range. Since American eels spend extended periods in freshwater, understanding their habitat requirements while freshwater residents is important for the management and conservation of this species. As there is little information on American eel habitat use in streams, the ontogenetic, diel, and seasonal habitat use as well as habitat selectivity of three size groups (i.e. ≤199 mm total length, 200–399 mm, ≥400 mm) of eel were examined in a tributary of the Hudson River. American eels in Hannacroix Creek exhibited ontogenetic, diel, and seasonal variation in habitat use as well as habitat selection. During both summer and autumn all sizes of American eels used larger substrate and more cover during the day. American eels ≤199 mm exhibited the strongest habitat selection, whereas eels 200–399 mm exhibited the least. During the autumn all sizes of American eels occupied slower depositional areas where deciduous leaf litter accumulated and provided cover. This may have important implications for in-stream and riparian habitat management of lotic systems used by American eel.

  17. Anthropogenic impacts on American eel demographics in Hudson River tributaries, New York

    USGS Publications Warehouse

    Machut, L.S.; Limburg, K.E.; Schmidt, R.E.; Dittman, D.

    2007-01-01

    Populations of American eel Anguilla rostrata along the eastern coast of North America have declined drastically for largely unknown reasons. We examined the population dynamics of American eels in six tributaries of the Hudson River, New York, to quantify their distribution and the impacts of anthropogenic stressors. With up to 155 American eels per 100 m2, tributary densities are greater than those within the main stem of the Hudson River and are among the highest reported anywhere. The predominance of small American eels (<200 mm) and wide range of ages (from young-of-year glass eels to 24-year-old yellow eels) suggest that tributaries are an important nursery area for immature American eels. However, upstream of natural and artificial barriers, American eel densities were reduced by at least a factor of 10 and condition, as measured by mass, was significantly lower. Significantly lower American eel condition was also found with increasing riparian urbanization. Density-dependent growth limitations below barriers are suggested by increased growth rates above the first tributary barrier. We suggest that (1) tributaries are important habitat for the conservation of American eels and (2) mitigation of anthropogenic stressors is vital for complete utilization of available habitat and conservation of the species. ?? Copyright by the American Fisheries Society 2007.

  18. Giant Scours on the Eel Canyon Fan

    NASA Astrophysics Data System (ADS)

    Lundsten, E.; Caress, D. W.; Paull, C. K.; Thomas, H.; Anderson, K.; Gwiazda, R.

    2011-12-01

    Previously available surface vessel multi-beam data collected on the deep-sea fan directly down channel from the mouth of Eel Canyon off of Northern California show a train of at least 8 giant elongated asymmetric depressions that look like giant scour features. High-resolution multi-beam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m) and 1-4.5 kHz Chirp seismic reflection profiles were collected in July 2011 over two of these large topographic depressions. The surveys were conducted using an autonomous underwater vehicle (AUV) during two 17.5-hour-long dives in 2,717 to 2,533 m water depths and focused on a 4.8 km long by 4.0 km wide area. An inertial navigation system combined with a Doppler velocity sonar allowed the AUV to fly pre-programmed grids at 3 knots while maintaining an altitude of 50 m above the seafloor. Our high-resolution surveys reveal the fine-scale morphology and shallow seafloor structure of two of these giant scours. The two depressions are up to 100 m deeper than the surrounding seafloor, up to 3.4 km long (N-S axis), up to 1.8 km wide (E-W axis), and markedly asymmetric in the E-W depth profile. Distinctive arcuate scarps which slope at ~ 27° form the eastern (upstream) edge of both depressions. While the seafloor surrounding these scarps is smooth, the scarp face shows horizontal lineations that are interpreted to be outcrops of bedding surfaces. Apparently seafloor erosion focused on the face of this scarp has exposed an ~100 m thick stratigraphic section. The bathymetry also shows numerous E-W oriented ridges ~180 m in length and perpendicular to the overall trace of these scarp, resulting in a serrated or scalloped appearance. The ridges on the scarp faces have an average spacing of 70 m and are separated by intervening gullies. Whether these ridges represent more resistant joints or are a consequence of lateral variations in overriding erosive flows is unclear. The deepest areas within these depressions

  19. Isolation of a novel polyomavirus, related to Japanese eel endothelial cell-infecting virus, from marbled eels, Anguilla marmorata (Quoy & Gaimard).

    PubMed

    Wen, C M; Chen, M M; Wang, C S; Liu, P C; Nan, F H

    2016-07-01

    Marbled eels, Anguilla marmorata (Quoy & Gaimard), cultured in Taiwan exhibited haemorrhage and mortality in January 2012. The severely diseased eels bled from the gills and showed congestion of the central venous sinus of the gill filaments and haemorrhage throughout the body similar to viral endothelial cell necrosis of eel. In this study, a novel polyomavirus (AmPyV) was isolated from the diseased eels using the AMPF cell line established from the pectoral fin of healthy marbled eels. AmPyV was found to encode a long T-antigen orthologous gene. Phylogenetic analysis showed that AmPyV was closely related to Japanese eel endothelial cell-infecting virus. PCR assays revealed AmPyV infection throughout the systemic organs. AmPyV proliferated in the AMPF, EK-1 and EO-2 cells at temperatures 25-30 °C, and the progeny virus yields were 10(7.0) , 10(7.4) and 10(7.7) TCID50  mL(-1) , respectively. The purified virions were icosahedral particles, 70-80 nm in diameter. No clinical signs or mortality was observed among the eels injected with the virus; however, the virus was reisolated from the brain, eyes, kidneys, fins and gills of infected eels 2 month after injection. Our results suggest that AmPyV exhibits a latent infection. Pathogen of the disease needs to study further. PMID:26566584

  20. Study of motion of flexible eel from the wake of bluff body in a cross flow

    NASA Astrophysics Data System (ADS)

    Sin, Vai Kuong; Deng, Wen Yue; Xiao, Wei Hang

    2012-09-01

    In this research, interaction between eel and vortex shedding behind a bluff body is studied numerically, aiming to optimize the oscillation of eels by coupling with the altering vertices. Effects of different factors such as length of eel, width of bluff body and flow speed on vibration of eels are also aimed to be investigated. A 2-dimensional Fluid-Structure Interaction Model that simulates the motion of eel under vortex shedding behind a bluff body is constructed by using the computational fluid dynamics (CFD) software - COMSOL Multiphysics. Simulations based on laminar flow regime are performed and the results show that undulating motion of the eel is successfully modeled with the Fluid-Structure Interaction Model along with Arbitrary Lagrangian-Eulerian (ALE) method.

  1. Interpretation of O K-edge EELS in zircon using a structural variation approach

    SciTech Connect

    Spence, John C.H; Jiang, Nan

    2009-12-01

    This work describes an approach to interpret the near-edge fine structure of electron energy-loss spectroscopy (EELS) of O K-edge in zircon using a structural variation method. The positions and intensities of several peaks in the O K-edge EELS spectrum are assigned to specific structural parameters. It suggests that the near-edge structures in EELS can be used to measure atomic structure changes.

  2. Patterns of infracommunity species richness in eels, Anguilla anguilla.

    PubMed

    Norton, J; Rollinson, D; Lewis, J W

    2004-06-01

    Between October 1999 and October 2001, a total of 510 European eels Anguilla anguilla were captured in 13 different samples from the rivers Thames (five locations) and Test (one location) in southern England. The relationship between parasite component community species richness (CCR) and maximum infracommunity species richness (ICRmax) compared with that previously observed in bird and mammal hosts. Specifically, the maximum number of parasite species occurring in infracommunities equalled or exceeded half the number of parasite species in the component community at that time, across a wide range of CCR values (2-9 parasite species). Furthermore, the frequency distribution of infracommunity richness (ICR) suggested that the species composition of infracommunities is probably random. These findings suggest that intestinal macroparasite infracommunities in eels are unsaturated and potentially species rich assemblages and, in these respects, share a fundamental similarity with the infracommunities of birds and mammals. PMID:15153286

  3. The speciation of conger eel galectins by rapid adaptive evolution.

    PubMed

    Ogawa, Tomohisa; Shirai, Tsuyoshi; Shionyu-Mitsuyama, Clara; Yamane, Takashi; Kamiya, Hisao; Muramoto, Koji

    2004-01-01

    Many cases of accelerated evolution driven by positive Darwinian selection are identified in the genes of venomous and reproductive proteins. This evolutional phenomenon might have important consequences in their gene-products' functions, such as multiple specific toxins for quick immobilization of the prey and the establishment of barriers to fertilization that might lead to speciation, and in the molecular evolution of novel genes. Recently, we analyzed the molecular evolution of two galectins isolated from the skin mucus of conger eel (Conger myriaster), named congerins I and II, by cDNA cloning and X-ray structural analysis, and we found that they have evolved in the rapid adaptive manner to emergence of a new structure including strand-swapping and a unique new ligand-binding site. In this review article we summarize and discuss the molecular evolution, especially the rapid adaptive evolution, and the structure-function relationships of conger eel galectins. PMID:14758068

  4. Characterization and differential expression patterns of conserved microRNAs and mRNAs in three genders of the rice field eel (Monopterus albus).

    PubMed

    Gao, Yu; Guo, Wei; Hu, Qing; Zou, Ming; Tang, Rong; Chi, Wei; Li, Dapeng

    2014-01-01

    MicroRNAs (miRNAs) are endogenous small RNAs that can regulate target mRNAs by binding to their sequences in the 3' untranslated region. The expression of miRNAs and their biogenetic pathway are involved in sexual differentiation and in the regulation of the development of germ cells and gonadal somatic cells. The rice field eel (Monopterus albus) undergoes a natural sexual transformation from female to male via an intersex stage during its life cycle. To investigate the molecular mechanisms of this sexual transformation, miRNAs present in the different sexual stages of the rice field eel were identified by high-throughput sequencing technology. A significantly differential expression among the 3 genders (p < 0.001) was observed for 48 unique miRNAs and 3 miRNAs*. Only 9 unique miRNAs showed a more than 8-fold change in their expression among the 3 genders, including mal-miR-430a and mal-miR-430c which were higher in females than in males. However, mal-miR-430b was only detected in males. Several potential miRNA target genes (cyp19a, cyp19b, nr5a1b, foxl2 amh, and vasa) were also investigated. Real-time RT-PCR demonstrated highly specific expression patterns of these genes in the 3 genders of the rice field eel. Many of these genes are targets of mal-miR-430b according to the TargetScan and miRTarBase. These results suggest that the miR-430 family may be involved in the sexual transformation of the rice field eel. PMID:25427634

  5. Electrochemical Capacitors with High Output Voltages that Mimic Electric Eels.

    PubMed

    Sun, Hao; Fu, Xuemei; Xie, Songlin; Jiang, Yishu; Peng, Huisheng

    2016-03-01

    A new family of energy-storage devices is created by mimicking the electric eel to obtain a high output voltage. These novel energy-storage devices are flexible, stretchable, and weavable fibers, which satisfies the needs of next-generation portable and wearable electronics. The devices are fabricated via a continuous fabrication technology to effectively power electronic watches and light-emitting diodes as two examples. PMID:26766594

  6. The role of olfaction in homing and estuarine migratory behavior of yellow-phase American eels

    USGS Publications Warehouse

    Barbin, G.P.

    1998-01-01

    The role of olfaction in homing migrations of American eels (Anguilla rostrata) was examined in the Penobscot Estuary, Maine, U.S.A. Ultrasonic telemetry was used to track continuously (65 ?? 12 h) 16 yellow eels displaced from a capture site. Four eels were not treated, eight rendered anosmic, and four rendered partially anosmic. All normal, only three anosmic, and two partially anosmic eels homed. Normal eels expressed a singular behavioral pattern, selective tidal stream transport (STST). STST was also displayed by three anosmic eels and one partially anosmic eel. Three alternative behavioral patterns ('sporadic vertical excursions,' 'sloshing,' and 'directed swimming') were displayed by the remainder of the anosmic and partially anosmic eels. Eels that displayed STST used the water column differently (moving at depths shallower than the thermocline, halocline, and pycnocline) from those that displayed other behaviors. Olfaction seems to be important for discrimination of the appropriate tide for transport and location of a home site but is not the only orientational mechanism used in estuaries. Mechanisms used to detect rates of change of water mass characteristics are probably important for guidance of estuarine migrations.

  7. A semi-automated method of monitoring dam passage of American Eels Anguilla rostrata

    USGS Publications Warehouse

    Welsh, Stuart; Aldinger, Joni L.

    2014-01-01

    Fish passage facilities at dams have become an important focus of fishery management in riverine systems. Given the personnel and travel costs associated with physical monitoring programs, automated or semi-automated systems are an attractive alternative for monitoring fish passage facilities. We designed and tested a semi-automated system for eel ladder monitoring at Millville Dam on the lower Shenandoah River, West Virginia. A motion-activated eel ladder camera (ELC) photographed each yellow-phase American Eel Anguilla rostrata that passed through the ladder. Digital images (with date and time stamps) of American Eels allowed for total daily counts and measurements of eel TL using photogrammetric methods with digital imaging software. We compared physical counts of American Eels with camera-based counts; TLs obtained with a measuring board were compared with TLs derived from photogrammetric methods. Data from the ELC were consistent with data obtained by physical methods, thus supporting the semi-automated camera system as a viable option for monitoring American Eel passage. Time stamps on digital images allowed for the documentation of eel passage time—data that were not obtainable from physical monitoring efforts. The ELC has application to eel ladder facilities but can also be used to monitor dam passage of other taxa, such as crayfishes, lampreys, and water snakes.

  8. Individual movements and population density estimates for moray eels on a Caribbean coral reef

    NASA Astrophysics Data System (ADS)

    Abrams, R. W.; Schein, M. W.

    1986-12-01

    Observations of moray eel (Muraenidae) distribution made on a Caribbean coral reef are discussed in the context of long term population trends. Observations of eel distribution made using SCUBA during 1978, 1979 1980, and 1984 are compared and related to the occurrence of a hurricane in 1979. An estimate of the mean standing stock of moray eels is presented. The degree of site attachment is discussed for spotted morays ( Gymnothorax moringa) and goldentail morays ( Muraena miliaris). The repeated non-aggressive association of moray eels with large aggregations of potential prey fishes is detailed.

  9. Anthropogenic noise compromises antipredator behaviour in European eels.

    PubMed

    Simpson, Stephen D; Purser, Julia; Radford, Andrew N

    2015-02-01

    Increases in noise-generating human activities since the Industrial Revolution have changed the acoustic landscape of many terrestrial and aquatic ecosystems. Anthropogenic noise is now recognized as a major pollutant of international concern, and recent studies have demonstrated impacts on, for instance, hearing thresholds, communication, movement and foraging in a range of species. However, consequences for survival and reproductive success are difficult to ascertain. Using a series of laboratory-based experiments and an open-water test with the same methodology, we show that acoustic disturbance can compromise antipredator behaviour--which directly affects survival likelihood--and explore potential underlying mechanisms. Juvenile European eels (Anguilla anguilla) exposed to additional noise (playback of recordings of ships passing through harbours), rather than control conditions (playback of recordings from the same harbours without ships), performed less well in two simulated predation paradigms. Eels were 50% less likely and 25% slower to startle to an 'ambush predator' and were caught more than twice as quickly by a 'pursuit predator'. Furthermore, eels experiencing additional noise had diminished spatial performance and elevated ventilation and metabolic rates (indicators of stress) compared with control individuals. Our results suggest that acoustic disturbance could have important physiological and behavioural impacts on animals, compromising life-or-death responses. PMID:25098970

  10. Nicolas and Eel submarine fans, California continental borderland

    SciTech Connect

    Reynolds, S.; Gorsline, D.S.

    1987-04-01

    Nicolas and Eel Submarine Fans occur in the San Nicolas basin - an outer basin of the California continental borderland that has a low sedimentation rate. Nicolas Fan lies southeast of San Nicolas Island and the broad San Nicolas Bank. The upper fan is characterized by numerous channels. The midfan region may be divided into three distinct areas: a central midfan and two subfans. The central midfan deposition system is typical of Normark's suprafan. The subfans are essentially flat, sandy lobes. Eel Fan lies west of San Clemente Island and is fed by an erosional valley. Its midfan region may also be characterized as a flat, sandy lobe. Box-core data show that holocene turbidity currents have occurred on the central Nicolas Fan, whereas the subfans and Eel Fan are nearly inactive. The local tectonic regime influences these fans by determining slope trends, creating bathymetric obstacles, controlling canyon location, and triggering mass movements. Sea level changes affect sedimentation patterns of the fans by increasing the mean grain size and the amount of sediment delivered to the fan during lowstands. These changes may, in turn, affect the morphology of the fan. The characteristics of these fans represent variations of the generalized fan models described in the literature. 12 figures, 1 table.

  11. First artificial hybrid of the eel species Anguilla australis and Anguilla anguilla

    PubMed Central

    2011-01-01

    Background Studies on artificial hybridization of different Anguilla species were conducted recently, i.e. female A. australis with male A. dieffenbachii, and female A. japonica with male A. anguilla. The existence of these artificial hybrids was however not demonstrated by independent genetic methods. Two species - A. anguilla and A. australis - that are phylogenetically close but have different sexual maturation times (12-25 weeks and 6-8 weeks, respectively), were expected to produce favourable hybrids for reproduction studies. Results A modification of the protocol for the reproduction of Anguilla japonica was used to produce eight-day Anguilla australis larvae, with a success rate of 71.4%. Thus ten out of 14 females produced eggs that could be fertilized, and three batches resulted in mass hatching. Hybrid larvae from female A. australis x male A. Anguilla survived for up to seven days post fertilization (dpf). The early development of the hybrid showed typical characteristics of A. anguilla tail pigmentation at 50 hours post fertilization (hpf), indicating expression of genes derived from the father. Conclusions In this paper we describe the first production of hybrid larvae from male A. anguilla and female A. australis and their survival for up to 7 dpf. A species-specific nucleotide difference in the 18 S rDNA gene confirmed that genes from both A. australis and A. anguilla were present in the hybrids. The developmental stages of the hybrid eel embryos and larvae are described using high resolution images. Video footage also indicated a heart beat in 5-dpf larva. PMID:21396126

  12. Morphometric relations in the grey eel catfish Plotosus canius in the coastal waters of Port Dickson, Peninsular Malaysia.

    PubMed

    Usman, B I; Amin, S M N; Arshad, A; Kamarudin, M S

    2016-07-01

    Samples of grey eel catfish Plotosus canius were collected from the coastal waters of Port Dickson, Malaysia from January to December, 2012. A total of 341 specimens (172 males and 169 females) were used to estimate the length-weight relationship parameters. Mean population size of females were 0.72 cm taller than the males, however difference was not significant (t-test, P > 0.05). The overall relationship equations between total length (TL) and body weight (BW) were established for males as Log TW = 2.71 Log TL - 1.85 (R2 = 0.95) and for females as Log TW = 2.88 Log TL-2.10 (R2 = 0.95). The estimated relative growth co-efficient (b) values were 2.71 for males and 2.88 for females. It is revealed that growth pattern of the species showed negative allometry. In both males and females, relationship between TL and SL gave highest regression coefficient (0.99). While relationship between TL and EL gave lowest regression coefficient in both males and females (0.87 and 0.81 respectively). The findings from this study contributed first information on morphometric relations of the fish from Malaysian coastal waters and could be useful for sustainable management options of P. canius in Malaysia. PMID:27498503

  13. Studies on the reproductive biology of spiny eel, Macrognathus aral from upper Assam.

    PubMed

    Abujam, Santoshkumar Singh; Biswas, S P

    2011-09-01

    The one-stripe spiny eel, Macrognathus aral (Bloch and Schneider), has been gaining importance not only as a food fish but also as an aquarium fish for its body shape and behaviour. The overall M:F ratio recorded 1:0.27, both the males and females were mostly mature in May-August. The peak values of gonado somatic ratio (GSR) attained during May for males (1.3) and August forfemales (12.4) indicating that the fish have only one breeding season during summer. The range of ova diameter was found to vary from 0.3 to 1.4 mm, the absolute fecundity ranged from 250 (21.6 cm/27.4 g) to 5220.1 (27.2 cm/66.3 g) while relative fecundity ranged from 9.1 to 128.9. The 50% maturity is attained in length group of 10.1-14 cm for males and 14.1-18 cm for females. The species is a moderately fecund, isochronal spawner and having a restricted breeding season. The relationship between fecundity and body weight and length has also been discussed. PMID:22319881

  14. Fall diel diet composition of American eel (Anguilla rostrata) in a tributary of the Hudson River, New York, USA

    USGS Publications Warehouse

    Waldt, Emily M.; Abbett, Ross; Johnson, James H.; Dittman, Dawn E.; McKenna, James E.

    2013-01-01

    American eel (Anguilla rostrata), a once common species, is now in decline throughout much of its native range in North America. There is little information on the role of American eel in river food webs. A better understanding of the diet and ecological role of American eel will help in the conservation of this important species. During autumn 2009, eel and aquatic invertebrate samples were collected from Hannacroix Creek, a tributary of the Hudson River, in Albany and Greene counties, New York, USA. Eel diet was analyzed by the eel size and time period (day or night). A high proportion of eel stomachs were empty (73%). Eel diets varied among size classes and day and night feeding periods (p = 0.001). Diet overlap was significant between small and medium eels caught both during the day (α = 0.71) and at night (α = 0.84). Nocturnal diet and nocturnal invertebrate samples were similar (α = 0.65), indicating a preference for bottom feeding during the night. Mayfly nymphs were the major prey consumed in each period by all size classes. Among eels that fed, night-feeding eels had the greatest stomach weight (as a percent of total body weight). The swim-bladder parasite, Anguillicoloides crassus, was also observed in eels of all size classes with nearly 50% afflicted.

  15. Population dynamics of cestode, Circumonchobothrium shindei (Cestoda: Pseudophyllidea Carus, 1863) in the freshwater eel, Mastacembelus armatus Lacépède, 1800 from River Godavari, Rajahmundry.

    PubMed

    Vankara, Anu Prasanna; Vijayalakshmi, C

    2015-06-01

    The freshwater eel, Mastacembelus armatus Lacépède, 1800 is often found infected with adults and larval plerocercoids of the cestode, Circumonchobothrium shindei. The population dynamics of C. shindei was studied in the freshwater eel, M. armatus during September 2005 to August 2007 from Godavari River, Rajahmundry. A total of 494 eels were examined; 184 (37.24 %) were infected with this cestode. Infection intensity ranged from 1 to 13 for C. shindei and their plerocercoids. C. shindei occupy the position of secondary species in community structure of metazoan parasites of M. armatus, with mean intensity, mean abundance and index of infection (2.5 ± 1.22; 1.1 ± 1.45 and 0.57 respectively). The present investigation deals with monthly population dynamics of C. shindei in M. armatus which summarizes percentage of prevalence, intensity, abundance and index of infection. Medium sized fish depicted more infection with this cestode and female fish illustrates comparatively higher infection rate than male fish. PMID:26064020

  16. Parasite infracommunity diversity in eels: a reflection of local component community diversity.

    PubMed

    Norton, J; Lewis, J W; Rollinson, D

    2003-11-01

    The intestinal macroparasite communities of freshwater eels (Anguilla anguilla) captured in the south of England from Windsor (River Thames) during August 2001, and Leckford (River Test) during late June/July 2000, are reported for the first time. Parasite component communities were among the most species rich and diverse recorded from European eels. A total of 13 intestinal macroparasite species were encountered during the study, 8 from each eel host population with 3 being common to both. Acanthocephalans, nematodes and cestodes were recovered from each host population. Eels from Windsor additionally harboured Nicolla gallica (Digenea), which was also the most prevalent and abundant macroparasite species in these hosts. Each component community followed a log normal rank abundance distribution and demonstrated reduced species dominance and increased species equitability compared with previous studies. As such, the study component communities were suitable for testing the hypothesis of low infracommunity diversity in European eel hosts. Specifically, this hypothesis predicts that the intestinal macroparasite infracommunities of European eels are species-poor, displaying low density and diversity with high dominance, irrespective of component community diversity, and that this may be more pronounced in UK host populations. This hypothesis was not upheld; study findings demonstrate that higher infracommunity diversity in eel hosts is possible, and suggest that infracommunity diversity in individual eel hosts may be a simple, stochastic reflection of component community diversity. PMID:14653536

  17. Leaping eels electrify threats, supporting Humboldt's account of a battle with horses.

    PubMed

    Catania, Kenneth C

    2016-06-21

    In March 1800, Alexander von Humboldt observed the extraordinary spectacle of native fisherman collecting electric eels (Electrophorus electricus) by "fishing with horses" [von Humboldt A (1807) Ann Phys 25:34-43]. The strategy was to herd horses into a pool containing electric eels, provoking the eels to attack by pressing themselves against the horses while discharging. Once the eels were exhausted, they could be safely collected. This legendary tale of South American adventures helped propel Humboldt to fame and has been recounted and illustrated in many publications, but subsequent investigators have been skeptical, and no similar eel behavior has been reported in more than 200 years. Here I report a defensive eel behavior that supports Humboldt's account. The behavior consists of an approach and leap out of the water during which the eel presses its chin against a threatening conductor while discharging high-voltage volleys. The effect is to short-circuit the electric organ through the threat, with increasing power diverted to the threat as the eel attains greater height during the leap. Measurement of voltages and current during the behavior, and assessment of the equivalent circuit, reveal the effectiveness of the behavior and the basis for its natural selection. PMID:27274074

  18. Leaping eels electrify threats, supporting Humboldt’s account of a battle with horses

    PubMed Central

    Catania, Kenneth C.

    2016-01-01

    In March 1800, Alexander von Humboldt observed the extraordinary spectacle of native fisherman collecting electric eels (Electrophorus electricus) by “fishing with horses” [von Humboldt A (1807) Ann Phys 25:34–43]. The strategy was to herd horses into a pool containing electric eels, provoking the eels to attack by pressing themselves against the horses while discharging. Once the eels were exhausted, they could be safely collected. This legendary tale of South American adventures helped propel Humboldt to fame and has been recounted and illustrated in many publications, but subsequent investigators have been skeptical, and no similar eel behavior has been reported in more than 200 years. Here I report a defensive eel behavior that supports Humboldt’s account. The behavior consists of an approach and leap out of the water during which the eel presses its chin against a threatening conductor while discharging high-voltage volleys. The effect is to short-circuit the electric organ through the threat, with increasing power diverted to the threat as the eel attains greater height during the leap. Measurement of voltages and current during the behavior, and assessment of the equivalent circuit, reveal the effectiveness of the behavior and the basis for its natural selection. PMID:27274074

  19. Homing and movement of yellow-phase American eels in freshwater ponds

    USGS Publications Warehouse

    Lamothe, P.J.; Gallagher, M.; Chivers, D.P.; Moring, J.R.

    2000-01-01

    Ten yellow-phase American eels, Anguilla rostrata, were captured from Hammond Pond, a small freshwater pond located in central Maine, U.S.A. The eels were implanted with radio transmitters and released into nearby Hermon Pond. At the same time, 10 eels were captured from Hermon Pond, implanted with radio transmitters and returned to Hermon Pond to serve as a control group. The two ponds are connected by a 1.6km section of Souadabscook Stream. We tracked the 20 eels over the 90-day duration of the experiment. Four of the ten displaced eels returned to their home pond. None of the control fish were located outside of their home pond during the study. Three of the four eels that successfully returned to their home pond did so under the darkness of the new moon and the fourth made the journey during the first quarter moon phase. Location data showed that translocated and native eels tended to occupy different areas of Hermon Pond. This study provides evidence of homing behavior in American eels living in small freshwater ponds and indications that homing activity may be linked to lunar cycle.

  20. Duplicated CFTR isoforms in eels diverged in regulatory structures and osmoregulatory functions.

    PubMed

    Wong, Marty Kwok-Shing; Pipil, Supriya; Kato, Akira; Takei, Yoshio

    2016-09-01

    Two cystic fibrosis transmembrane conductance regulator (CFTR) isoforms, CFTRa and CFTRb, were cloned in Japanese eel and their structures and functions were studied in different osmoregulatory tissues in freshwater (FW) and seawater (SW) eels. Molecular phylogenetic results suggested that the CFTR duplication in eels occurred independently of the duplication event in salmonid. CFTRa was expressed in the intestine and kidney and downregulated in both tissues in SW eels, while CFTRb was specifically expressed in the gill and greatly upregulated in SW eels. Structurally, the CFTR isoforms are similar in most functional domains except the regulatory R domain, where the R domain of CFTRa is similar to that of human CFTR but the R domain of CFTRb is unique in having high intrinsic negative charges and fewer phosphorylation sites, suggesting divergence of isoforms in terms of gating properties and hormonal regulation. Immunohistochemical results showed that CFTR was localized on the apical regions of SW ionocytes, suggesting a Cl(-) secretory role as in other teleosts. In intestine and kidney, however, immunoreactive CFTR was mostly found in the cytosolic vesicles in FW eels, indicating that Cl(-) channel activity could be low at basal conditions, but could be rapidly increased by membrane insertion of the stored channels. Guanylin (GN), a known hormone that increases CFTR activity in mammalian intestine, failed to redistribute CFTR and to affect its expression in eel intestine. The results suggested that GN-independent CFTR regulation is present in eel intestine and kidney. PMID:27322796

  1. Electric Eels Concentrate Their Electric Field to Induce Involuntary Fatigue in Struggling Prey.

    PubMed

    Catania, Kenneth C

    2015-11-16

    Nature is replete with predator venoms that immobilize prey by targeting ion channels. Electric eels (Electrophorus electricus) take a different tactic to accomplish the same end. Striking eels emit electricity in volleys of 1 ms, high-voltage pulses. Each pulse is capable of activating prey motor neuron efferents, and hence muscles. In a typical attack, eel discharges cause brief, immobilizing tetanus, allowing eels to swallow small prey almost immediately. Here I show that when eels struggle with large prey or fish held precariously, they commonly curl to bring their own tail to the opposite side of prey, sandwiching it between the two poles of their powerful electric organ. They then deliver volleys of high-voltage pulses. Shortly thereafter, eels juggle prey into a favorable position for swallowing. Recordings from electrodes placed within prey items show that this curling behavior at least doubles the field strength within shocked prey, most likely ensuring reliable activation of the majority of prey motor neurons. Simulated pulse trains, or pulses from an eel-triggered stimulator, applied to a prey muscle preparations result in profound muscle fatigue and loss of contractile force. Consistent with this result, video recordings show that formerly struggling prey are temporarily immobile after this form of attack, allowing the manipulation of prey that might otherwise escape. These results reveal a unique use of electric organs to a unique end; eels superimpose electric fields from two poles, ensuring maximal remote activation of prey efferents that blocks subsequent prey movement by inducing involuntary muscle fatigue. PMID:26521183

  2. Genomic Sequence of a Ranavirus Isolated from Short-Finned Eel (Anguilla australis)

    PubMed Central

    Toffan, Anna; Cappellozza, Elisabetta; Steckler, Natalie K.; Olesen, Niels J.; Ariel, Ellen

    2016-01-01

    The short-finned eel ranavirus (SERV) was isolated from short-finned eel imported to Italy from New Zealand. Phylogenomic analyses revealed that SERV is a unique member of the genus Ranavirus, family Iridoviridae, branching at the base of the tree near other fish ranaviruses. PMID:27540067

  3. Effects of salinity and sea salt type on egg activation, fertilization, buoyancy and early embryology of European eel, Anguilla anguilla.

    PubMed

    Sørensen, Sune Riis; Butts, Ian Anthony Ernest; Munk, Peter; Tomkiewicz, Jonna

    2016-02-01

    Improper activation and swelling of in vitro produced eggs of European eel, Anguilla anguilla, has been shown to negatively affect embryonic development and hatching. We investigated this phenomenon by examining the effects of salinity and sea salt type on egg dimensions, cell cleavage patterns and egg buoyancy. Egg diameter after activation, using natural seawater adjusted to different salinities, varied among female eels, but no consistent pattern emerged. Activation salinities between 30-40 practical salinity unit (psu) produced higher quality eggs and generally larger egg diameters. Chorion diameters reached maximal values of 1642 ± 8 μm at 35 psu. A positive relationship was found between egg neutral buoyancy and activation salinity. Nine salt types were investigated as activation and incubation media. Five of these types induced a substantial perivitelline space (PVS), leading to large egg sizes, while the remaining four salt types resulted in smaller eggs. All salt types except NaCl treatments led to high fertilization rates and had no effect on fertilization success as well as egg neutral buoyancies at 7 h post-fertilization. The study points to the importance of considering ionic composition of the media when rearing fish eggs and further studies are encouraged. PMID:25707438

  4. The lipopolysaccharide O side chain of Vibrio vulnificus serogroup E is a virulence determinant for eels.

    PubMed Central

    Amaro, C; Fouz, B; Biosca, E G; Marco-Noales, E; Collado, R

    1997-01-01

    Vibrio vulnificus is a gram-negative bacterium capable of producing septicemic infections in eels and immunocompromised humans. Two biotypes are classically recognized, with the virulence for eels being specific to strains belonging to biotype 2, which constitutes a homogeneous lipopolysaccharide (LPS)-based O serogroup (which we have designated serogroup E). In the present study we demonstrated that the O side chain of this LPS determines the selective virulence of biotype 2 for eels: (i) biotype 1 strains (which do not belong to serogroup E) are destroyed by the bactericidal action of nonimmune eel serum (NIS) through activation of the alternative pathway of complement, (ii) biotype 2 strains (of serogroup E) are resistant to NIS, and (iii) rough mutants of biotype 2 lacking the O polysaccharide side chain are sensitive to NIS and avirulent for eels. PMID:9169795

  5. Mating system and size advantage of male mating in the protogynous swamp eel Monopterus albus with paternal care.

    PubMed

    Matsumoto, Seiji; Takeyama, Tomohiro; Ohnishi, Nobuhiro; Kohda, Masanori

    2011-05-01

    In fish with paternal care, protogynous sex change (female to male) is rare and has only been reported from species with haremic polygyny. The swamp eel, Monopterus albus, is a protogynous fish with paternal care, but little is known about its mating system. To understand protogyny in this species, we examined the mating system and male size advantage in mating in M. albus under semi-natural condition. Females swam over wide ranges and visited multiple male nests. Males defended a narrow territory around nests against other males that approached nests; at these nests, males courted and accepted visiting females. After spawning inside nests, caring males continued to perform courtship activities, and multiple breeding was observed. These observations suggest that the M. albus mating system is male-territory-visiting (MTV)-polygamy. Larger males had nests, and mated more frequently compared with small males. Because small initial males of this species are not found in nature, and because M. albus does not engage in sneaking tactics, larger nesting males do not suffer from reproductive parasitism. Thus, protogyny in this fish is likely consistent with the predictions of the size-advantage model. Biting attacks by territorial males of this predatory fish seriously wounded intruding males, occasionally resulting in the death of the intruder. We discuss the possibility that sexual differences in mortality rates in small fish may facilitate the evolution of protogyny in this species. Protogyny of the swamp eel is, to our knowledge, the first example of an MTV-polygamous mating system in a fish with paternal care. PMID:21557660

  6. Expression of Aromatase in Radial Glial Cells in the Brain of the Japanese Eel Provides Insight into the Evolution of the cyp191a Gene in Actinopterygians

    PubMed Central

    Jeng, Shan-Ru; Yueh, Wen-Shiun; Pen, Yi-Ting; Gueguen, Marie-Madeleine; Pasquier, Jérémy; Dufour, Sylvie; Chang, Ching-Fong; Kah, Olivier

    2012-01-01

    The cyp19a1 gene that encodes aromatase, the only enzyme permitting conversion of C19 aromatizable androgens into estrogens, is present as a single copy in the genome of most vertebrate species, except in teleosts in which it has been duplicated. This study aimed at investigating the brain expression of a cyp19a1 gene expressed in both gonad and brain of Japanese eel, a basal teleost. By means of immunohistochemistry and in situ hybridization, we show that cyp19a1 is expressed only in radial glial cells of the brain and in pituitary cells. Treatments with salmon pituitary homogenates (female) or human chorionic gonadotrophin (male), known to turn on steroid production in immature eels, strongly stimulated cyp19a1 messenger and protein expression in radial glial cells and pituitary cells. Using double staining studies, we also showed that aromatase-expressing radial glial cells exhibit proliferative activity in both the brain and the pituitary. Altogether, these data indicate that brain and pituitary expression of Japanese eel cyp19a1 exhibits characteristics similar to those reported for the brain specific cyp19a1b gene in teleosts having duplicated cyp19a1 genes. This supports the hypothesis that, despite the fact that eels also underwent the teleost specific genome duplication, they have a single cyp19a1 expressed in both brain and gonad. Such data also suggest that the intriguing features of brain aromatase expression in teleost fishes were not gained after the whole genome duplication and may reflect properties of the cyp19a1 gene of ancestral Actinopterygians. PMID:22957105

  7. Eel green fluorescent protein is associated with resistance to oxidative stress.

    PubMed

    Funahashi, Aki; Komatsu, Masaharu; Furukawa, Tatsuhiko; Yoshizono, Yuki; Yoshizono, Hikari; Orikawa, Yasuhiro; Takumi, Shota; Shiozaki, Kazuhiro; Hayashi, Seiichi; Kaminishi, Yoshio; Itakura, Takao

    2016-01-01

    Green fluorescent protein (GFP) from eel (Anguilla japonica) muscle (eelGFP) is unique in the vertebrates and requires bilirubin as a ligand to emit fluorescence. This study was performed to clarify the physiological function of the unique GFP. Investigation of susceptibility to oxidative stress was carried out using three types of cell lines including jellyfish (Aequorea coerulescens) GFP (jfGFP)-, or eel GFP (eelGFP)-expressing HEK293 cells, and control vector-transfected HEK293 cells. Binding of eelGFP to bilirubin was confirmed by the observation of green fluorescence in HEK293-eelGFP cells. The growth rate was compared with the three types of cells in the presence or absence of phenol red which possessed antioxidant activity. The growth rates of HEK293-CV and HEK293-jfGFP under phenol red-free conditions were reduced to 52 and 31% of those under phenol red. Under the phenol red-free condition, HEK293-eelGFP had a growth rate of approximately 70% of the phenol red-containing condition. The eelGFP-expressing cells were approximately 2-fold resistant to oxidative stress such as H2O2 exposure. The fluorescence intensity partially decreased or disappeared after exposure to H2O2, and heterogeneous intensity of fluorescence was also observed in isolated eel skeletal muscle cells. These results suggested eelGFP, but not jfGFP, coupled with bilirubin provided the antioxidant activity to the cells as compared to non-bound free bilirubin. PMID:26746389

  8. Temporal variations in embryotoxicity of Lake Ontario American eel (Anguilla rostrata) extracts to developing Fundulus heteroclitus.

    PubMed

    Rigaud, Cyril; Couillard, Catherine M; Pellerin, Jocelyne; Légaré, Benoît; Byer, Jonathan D; Alaee, Mehran; Lebeuf, Michel; Casselman, John M; Hodson, Peter V

    2016-01-15

    The recruitment of American eel (Anguilla rostrata) juveniles to Lake Ontario (LO), Canada has declined significantly since the 1980s. To investigate the possible contribution of maternally-transferred persistent organic pollutants (POPs) to this decline, this study measured temporal variations in the toxicity of complex organic mixtures extracted from LO American eels captured in 1988, 1998 and 2008 to developing Fundulus heteroclitus exposed by intravitelline (IVi) injection. The 1988 and 1998 eel extracts were most toxic, causing a pattern of sublethal embryotoxic responses similar to those previously reported in F. heteroclitus embryos exposed to single dioxin-like compounds (DLCs): stunted growth, craniofacial deformities, EROD activity induction, and reduced predatory capacities. The potency of extracts declined over time; the only significant effect of the 2008 eel extracts was EROD induction. The chemically-derived TCDD-TEQs of eel extracts, calculated using measured concentrations of some DLCs and their relative potencies for F. heteroclitus, overestimated their potency to induce EROD activity possibly due to interactions among POPs. Other POPs measured in eel extracts (non-dioxin-like PCBs, PBDEs and organochlorinated pesticides) did not appear to be important agonistic contributors to the observed toxicity. The toxicity of the complex mixtures of POPs measured in LO eels may have been underestimated as a result of several factors, including the loss of POPs during extracts preparation and a focus only on short-term effects. Based on the model species examined, our results support the hypothesis that contamination of LO with DLCs may have represented a threat to the American eel population through ecologically-relevant effects such as altered larval prey capture ability. These results prioritize the need to assess early life stage (ELS) toxicity of DLCs in Anguilla species, to investigate long-term effects of complex eel extracts to ELS of fish, and to

  9. Relativistic real-space multiple scattering calculations of EELS

    NASA Astrophysics Data System (ADS)

    Jorissen, K.; Rehr, J. J.; Sorini, A.; Levine, Z. H.

    2006-03-01

    We present an extension of the real space multiple scattering code FEFF8 for ab initio, relativistic calculations of electron energy loss spectra (EELS), which is applicable both to periodic and non-periodic systems. The approach explains the observed relativistic shifts in the magic angle. In addition, the method can account for experimental parameters such as collection and convergence angles of the microscope and sample orientation. We also discuss relativistic effects on inelastic electron scattering including the density correction to the stopping power. Our results are compared with other approaches and with experiment. B. Jouffrey, P. Schattschneider and C. Hebert, Ultramicroscopy 102, 61 (2004).

  10. First record of Anguillicoloides crassus (Nematoda) in American eels (Anguilla rostrata) in Canadian estuaries, Cape Breton, Nova Scotia.

    PubMed

    Rockwell, L S; Jones, K M M; Cone, D K

    2009-04-01

    In the summer of 2007, American eels, Anguilla rostrata, from 2 localities on Cape Breton Island, were found to be infected with the swim bladder nematode Anguillicoloides crassus. This is the first documented report of this highly invasive parasite in Canadian waters. More than half of the yellow eels in Mira River (6 of 10), and 1 eel (of 5) from Sydney Harbour were infected. Parasite intensity ranged from 1 to 11 worms per eel. The occurrence of A. crassus at these 2 localities suggests the need for a more extensive survey on the distribution of this exotic parasite in eel populations throughout Cape Breton Island. PMID:18767906

  11. Silver nanowires

    NASA Astrophysics Data System (ADS)

    Graff, A.; Wagner, D.; Ditlbacher, H.; Kreibig, U.

    2005-07-01

    Free silver nanowires were produced in aqueous electrolyte by a novel chemical reaction. Their diameters are about 27 nm, the lengths range up to more than 70 μm, yielding extreme length to thickness-ratios up to 2500. Their structure was identified by TEM analysis (SAED) and HRTEM to consist of a lattice aligned bundle of five monocrystalline rods of triangular cross-section forming an almost regular pentagonal cross-section. It is demonstrated that, for application purposes, single free nanowires can be mounted between contact areas. This manipulation is enabled by observing the nanowires in real time at atmosphere by Zsigmondy-Siedentopf farfield darkfield microscopy. Experimental results are presented concerning electrical dc conductivity and optical plasmon polariton excitation, the latter obtained from a single free wire without substrate and a single wire deposited on quartz glass. We also report about a present research cooperation with the Graz group of Aussenegg and Krenn which is devoted to investigate plasmon propagation in our Ag nanowires and to prove application possibilities as information guide fibers in analogy to optical fibers which may be integrated into micro- and nanoelectronic circuits.

  12. The Silver Halides

    ERIC Educational Resources Information Center

    Sahyun, M. R. V.

    1977-01-01

    Illustrates the type of fractional bonding for solid silver halides. Treats the silver halides as electron excess compounds, and develops a model of a localized bonding unit that may be iterated in three dimensions to describe the bulk phase. (MLH)

  13. Colloidal Silver Products

    MedlinePlus

    ... can be dangerous to your health. What the Science Says About the Safety and Side Effects of ... homemade and commercial colloidal silver products. What the Science Says About the Effectiveness of Colloidal Silver Scientific ...

  14. Steroid production in testicular tissue of the European eel

    SciTech Connect

    Eckstein, B.; Cohen, S.; Hilge, V.

    1982-03-01

    Testicular tissue of normal and hCG-stimulated European eels was incubated in vitro with tritiated progesterone or androstenedione as substrates. The following compounds were isolated and identified: 5 beta-androstane-3,17-dione; 17 beta-hydroxy-5 beta-androstan-3-one; androst-4-ene-3,11,17-trione (adrenosterone); 11 beta-hydroxyandrost-4-ene-3,17-dione; 11 beta-hydroxytestosterone; 3 alpha,11 beta-dihydroxy-5 beta-androstan-17-one, and an additional steroid for which the oxidation product was identified as 5 beta-androstene-3,11,17-trione. Four of these steroids have not been hitherto identified in gonadal tissue of any vertebrate. The pattern of steroid production in this tissue is unique for its 5 beta-reduction, for the appearance of adrenosterone as a major metabolite, and for the lack of production of 11-ketotestosterone, which is a regular metabolite of gonadal tissue of teleosts. Thus, it appears that steroid metabolism in the eel testis deviates considerably from the known pattern of steroid production in gonads of other vertebrates.

  15. Sodium affects the sperm motility in the European eel.

    PubMed

    Vílchez, M Carmen; Morini, Marina; Peñaranda, David S; Gallego, Víctor; Asturiano, Juan F; Pérez, Luz

    2016-08-01

    The role of seminal plasma sodium and activation media sodium on sperm motility was examined by selectively removing the element from these two media, in European eel sperm. Sperm size (sperm head area) was also measured using an ASMA (Automated Sperm Morphometry Analyses) system, in the different conditions. Intracellular sodium [Na(+)]i was quantitatively analyzed by first time in the spermatozoa from a marine fish species. Measurement of [Na(+)]i was done before and after motility activation, by Flow Cytometry, using CoroNa Green AM as a dye. Sperm motility activation induced an increase in [Na(+)]i, from 96.72mM in quiescent stage to 152.21mM post-activation in seawater. A significant decrease in sperm head area was observed post-activation in seawater. There was a notable reduction in sperm motility when sodium was removed from the seminal plasma, but not when it was removed from the activation media. Sodium removal was also linked to a significant reduction in sperm head area in comparison to the controls. Our results indicate that the presence of the ion Na(+) in the seminal plasma (or in the extender medium) is necessary for the preservation of sperm motility in European eel, probably because it plays a role in maintaining an appropriate sperm cell volume in the quiescent stage of the spermatozoa. PMID:27085371

  16. Downstream movement of mature eels in a hydroelectric reservoir in New Zealand

    USGS Publications Warehouse

    Watene, E.M.; Boubee, J.A.T.; Haro, A.

    2003-01-01

    This study investigates the behavior of migrant eels as they approached the Patea hydroelectric dam on the West Coast of the North Island, New Zealand. Seventeen mature migrant eels (870-1,240 mm; 2,000-6,380 g) were implanted with coded acoustic transmitters and released. Their movements in the reservoir were monitored for 14 months with stationary data logging and manual tracking receivers. The downstream migration of sexually maturing eels was found to occur mainly at night, usually during, or immediately after, rainfall events. Eels tended to travel at the surface, within the upper 4 m of the water column, at speeds ranging from 16 to 89 cm/s. Upon reaching the headrace, eels typically spent time searching, presumably for an unobstructed downstream route. In order to aid downstream passage of eels at the Patea Dam, power station operators began spillway opening trials during peak migration periods. Although this allowed some migrant eels to safely pass over the dam, information on the relative effectiveness and cost of this method over other possible mitigation methods is still required. ?? Copyright by the American Fisheries Society 2003.

  17. All roads lead to home: panmixia of European eel in the Sargasso Sea.

    PubMed

    Als, Thomas D; Hansen, Michael M; Maes, Gregory E; Castonguay, Martin; Riemann, Lasse; Aarestrup, Kim; Munk, Peter; Sparholt, Henrik; Hanel, Reinhold; Bernatchez, Louis

    2011-04-01

    European eels (Anguilla anguilla) spawn in the remote Sargasso Sea in partial sympatry with American eels (Anguilla rostrata), and juveniles are transported more than 5000 km back to the European and North African coasts. The two species have been regarded as classic textbook examples of panmixia, each comprising a single, randomly mating population. However, several recent studies based on continental samples have found subtle, but significant, genetic differentiation, interpreted as geographical or temporal heterogeneity between samples. Moreover, European and American eels can hybridize, but hybrids have been observed almost exclusively in Iceland, suggesting hybridization in a specific region of the Sargasso Sea and subsequent nonrandom dispersal of larvae. Here, we report the first molecular population genetics study based on analysis of 21 microsatellite loci in larvae of both Atlantic eel species sampled directly in the spawning area, supplemented by analysis of European glass eel samples. Despite a clear East-West gradient in the overlapping distribution of the two species in the Sargasso Sea, we only observed a single putative hybrid, providing evidence against the hypothesis of a wide marine hybrid zone. Analyses of genetic differentiation, isolation by distance, isolation by time and assignment tests provided strong evidence for panmixia in both the Sargasso Sea and across all continental samples of European eel after accounting for the presence of sibs among newly hatched larvae. European eel has declined catastrophically, and our findings call for management of the species as a single unit, necessitating coordinated international conservation efforts. PMID:21299662

  18. Influence of adult Anguillicoloides crassus load in European eels swimbladder on macrophage response.

    PubMed

    Muñoz, P; Peñalver, J; Ruiz de Ybañez, R; Garcia, J

    2015-02-01

    Anguillicoloides crassus has become one of the most important threats to the European eel (Anguilla anguilla). Adult parasites colonize the swimbladder leading to an impaired functioning of this organ. The infection is also responsible for an increased in the stress level of infected eels, that could produce an altered immune response as well. Differences in parasite loads and effects in the European and Japanese eel (Anguilla japonica) have been described. We have studied the influence of the number of adult parasites present in the swimbladder of wild eels on the macrophage response (phagocytosis and respiratory burst) as part of the first immune response to pathogens. Our results show an increased phagocytozed bacterial survival 24 h post-infection in macrophages of eels infected with more than ten adult parasites compared to macrophages from eels infected with less than those ten adult parasites. Respiratory burst results also showed a less efficient response in macrophages from eels infected with more than ten adult parasites, although in this case results were not found to be significant. PMID:25463301

  19. Environmental correlates of upstream migration of yellow-phase American eels in the Potomac River drainage

    USGS Publications Warehouse

    Welsh, Stuart; Heather L. Liller

    2013-01-01

    Assessing the relationships between upstream migration and environmental variables is important to understanding the ecology of yellow-phase American Eels Anguilla rostrata. During an American Eel migration study within the lower Shenandoah River (Potomac River drainage), we counted and measured American Eels at the Millville Dam eel ladder for three periods: 14 May–23 July 2004, 7–30 September 2004, and 1 June–31 July 2005. Using generalized estimating equations, we modeled each time series of daily American Eel counts by fitting time-varying environmental covariates of lunar illumination (LI), river discharge (RD), and water temperature (WT), including 1-d and 2-d lags of each covariate. Information-theoretic approaches were used for model selection and inference. A total of 4,847 American Eels (19–74 cm total length) used the ladder during the three periods, including 2,622 individuals during a 2-d span following a hurricane-induced peak in river discharge. Additive-effects models of RD + WT, a 2-d lag of LI + RD, and LI + RD were supported for the three periods, respectively. Parameter estimates were positive for river discharge for each time period, negative for lunar illumination for two periods and positive for water temperature during one period. Additive-effects models supported synergistic influences of environmental variables on the upstream migration of yellow-phase American Eels, although river discharge was consistently supported as an influential correlate of upstream migration.

  20. Maternally transferred dioxin-like compounds can affect the reproductive success of European eel.

    PubMed

    Foekema, Edwin M; Kotterman, Michiel; de Vries, Pepijn; Murk, Albertinka J

    2016-01-01

    Reported concentrations of dioxin-like compounds accumulated in the European eel (Anguilla anguilla) were used to perform a risk assessment for eel larval survival, taking into account a modeled amplification of tissue concentrations with a factor of 1.33 during spawning migration. The calculated concentrations of dioxin-like compounds finally deposited in the eggs were compared with the internal effect concentrations for survival of early life stages of the European eel; these concentrations, by lack of experimental data, were estimated from a sensitivity distribution based on literature data by assuming that eel larvae are among the 10% most sensitive teleost fish species. Given concentrations of dioxin-like contaminants and assuming a relatively high sensitivity, it can be expected that larvae from eggs produced by eel from highly contaminated locations in Europe will experience increased mortality as a result of maternally transferred dioxin-like contaminants. As historical persistent organic pollutant concentrations in eel tissue were higher, this impact must have been stronger in the past. Potential effects of other compounds or effects on the migration, condition, and fertility of the parental animals were not taken into account. It is important to further study the overall impact of contaminants on the reproductive success of the European eel as this may have been underestimated until now. PMID:26223357

  1. Impact of long-term habitat loss on the Japanese eel Anguilla japonica

    NASA Astrophysics Data System (ADS)

    Chen, Jian-Ze; Huang, Shiang-Lin; Han, Yu-San

    2014-12-01

    Since the 1970s, the loss of temperate-zone anguillid eels, particularly Anguilla anguilla, Anguilla rostrata, and Anguilla japonica, has exceeded 90% based on estimates of glass eel recruitment. The cause of this decline has not been conclusively determined, although many factors have been proposed. In East Asia, the consequences of long-term habitat loss and deterioration of habitat quality on the sustainability of Japanese eel resources are important. Impacts have already occurred and are expected to increase because hundreds of millions of people live near estuaries and rivers that have undergone, and further, are expected to continue to undergo, substantial changes in land use. Driven by economic growth, these landscape changes have resulted in, and may continue to produce, the large-scale destruction of eel habitats. We used chronological Landsat imagery to measure Japanese eel habitat reduction from human activities in 16 rivers in East Asia, including Japan, Korea, Taiwan, and China. On average, 76.8% of the effective habitat area (Ae) was lost in these 16 rivers from the 1970s-2010s. Taiwan and China had the highest percentages of Ae loss, with declines of 49.3% and 81.5%, respectively. Extensive habitat loss may play an important role, together with regional climate phenomena such as the ENSO and overfishing, in the decline of the Japanese eel in East Asia. Measures targeting habitat restoration and protection may need to be integrated into management planning for Japanese eel resources in an international rather than regional context.

  2. Stage-specific distribution models can predict eel (Anguilla anguilla) occurrence during settlement in coastal lagoons

    NASA Astrophysics Data System (ADS)

    Leone, C.; Zucchetta, M.; Capoccioni, F.; Gravina, M. F.; Franzoi, P.; Ciccotti, E.

    2016-03-01

    Eel (Anguilla anguilla) is a catadromous fish species typical of Mediterranean coastal lagoons, that currently suffers from several anthropogenic and natural impacts. These are thought to be the cause of a stock-wide decline that this panmictic species is facing, in inland and coastal waters of Europe and North Africa. The decline affects both adult phases and recruitment, i.e. glass eel arrival to coastal waters and their ascent to inland waters. Quantitative features of eel recruitment reflect a transoceanic global scale, but also depend on local environmental conditions, the latter also affecting settlement dynamics in transitional waters. There is only little information on the dynamics of these two processes in coastal lagoons, notwithstanding the paramount importance of both in sustaining local stocks abundance and their demographic structure for this typical but also economically important inhabitant of Mediterranean lagoons, habitats that constitute an important share of the eel distribution area. The present study aims, therefore, to clarify space and time dynamics of local scale recruitment and of settlement in a coastal lagoon in the Mediterranean area, also by setting up a specific methodological approach. For this purpose, data from field surveys in combination with Species Distribution Models (SDMs) have been used in order to relate distribution of eel juvenile stages to the environmental conditions within the lagoon. Specifically, models were calibrated to quantify the relationship between presence of juvenile eel and the main environmental drivers, with the aim of identifying potential habitats for eel settlement within the lagoon. Results gained by modelling suggest certain spatial and temporal colonization patterns for the juvenile eel in the Fogliano lagoon, a typical Mediterranean coastal lake. The modelling approach has therefore proved to be a useful tool for predicting habitats for eel recruitment at the local scale and settlement, because

  3. Methylmercury effects on migratory behaviour in glass eels (Anguilla anguilla): an experimental study using isotopic tracers.

    PubMed

    Claveau, Julie; Monperrus, Mathilde; Jarry, Marc; Baudrimont, Magalie; Gonzalez, Patrice; Cavalheiro, Joana; Mesmer-Dudons, Nathalie; Bolliet, Valérie

    2015-05-01

    The effect of methylmercury (MeHg) on glass eels' propensity to migrate, mitochondrial activity and antioxidative defence systems was investigated. Marine glass eels were first sorted in an experimental flume according to their response to dusk. Fish responding to the decrease in light intensity by ascending in the water column and moving with or against the flow were considered as having a high propensity to migrate (migrant). Glass eels still sheltering at the end of the 24 h catching period were considered as having a low propensity to migrate and were called non-migrant. Migrant and non-migrant glass eels were then individually tagged and exposed to isotopically enriched (201)MeHg (50 ng L(-1)) for 11 days. The effect of contamination was studied on muscle fibre structure, and the expression level of genes involved in mitochondrial activity and antioxidative defence systems. To investigate the effect of MeHg on glass eel behaviour, migrant and non-migrant glass eels were sorted again and the bioaccumulation of (201)MeHg and its demethylation product ((201)Hg(II)) were determined for each individual. MeHg exposure increased activity in non-migrant glass eels but not migratory behaviour. Contamination affected mitochondrial structure and metabolism and suggests a higher oxidative stress and activation of antioxidative defence systems in non-migrant glass eels. Overall, our results suggest that exposure to MeHg might induce an increase in energy expenditure and a higher vulnerability to predation in non-migrant glass eels in the wild. PMID:25797033

  4. Prevalence of Gnathostoma spinigerum infection in wild and cultured swamp eels in Vietnam.

    PubMed

    Sieu, Tran Phu Manh; Dung, Tran Thi Kim; Nga, Nguyen Thi Quynh; Hien, Tran Vinh; Dalsgaard, Anders; Waikagul, Jitra; Murrell, K Darwin

    2009-02-01

    Human infections with Gnathostoma spinigerum frequently occur in southern Vietnam. Previous investigations have implicated infected swamp eels (Monopterus albus) as an important source of infection to humans. Because aquaculture of M. alba is an important farming activity in Vietnam, a 2-yr study was carried out to assess the relative importance of farmed and wild eels as potential sources of gnathostome infections in humans. Eels sold for public consumption in markets in southern provinces were examined between November 2005 and August 2007. Although no infections were detected in 1,020 cultured eels and 1,021 wild-caught eels collected from November 2005 to September 2006, larval G. spinigerum (AL3) infections were first detected in September 2006 in 28 of 230 wild-caught eels (12.2%) obtained from markets in Long An province and the Hoc Mon district of Ho Chi Minh City. Subsequently, monthly surveillance of wild-caught eels from these markets was carried out through August 2007. Prevalence of AL3 varied monthly, ranging from 0.8 to 19.6%. Both prevalence and infection intensity were higher during the latter part of the rainy season (August- October). These results demonstrate that potentially zoonotic G. spinigerum larvae are common in wild eels in southern Vietnam and present a risk to consumers of raw fish dishes, especially during the annual rainy season. This information could help target public health education efforts in the region. The basis for the seasonal variation on eel infections is not known, but may be related to climate effects (flooding, higher temperatures) on intermediate host species ecology. PMID:19245276

  5. Dramatic effect of pop-up satellite tags on eel swimming

    NASA Astrophysics Data System (ADS)

    Burgerhout, Erik; Manabe, Ryotaro; Brittijn, Sebastiaan A.; Aoyama, Jun; Tsukamoto, Katsumi; van den Thillart, Guido E. E. J. M.

    2011-07-01

    The journey of the European eel to the spawning area in the Sargasso Sea is still a mystery. Several trials have been carried out to follow migrating eels with pop-up satellite tags (PSATs), without much success. As eels are very efficient swimmers, tags likely interfere with their high swimming efficiency. Here we report a more than twofold increase in swimming cost caused by a regular small satellite tag. The impact was determined at a range of swimming speeds with and without tag in a 2-m swimming tunnel. These results help to explain why the previous use of PSATs to identify spawning sites in the Sargasso Sea was thus far unsuccessful.

  6. Optimization of silver-dielectric-silver nanoshell for sensing applications

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-15

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  7. Effects of recombinant eel growth hormone on the uptake of ( sup 35 S)sulfate by ceratobranchial cartilages of the Japanese eel, Anguilla japonica

    SciTech Connect

    Duan, C.M.; Inui, Y. )

    1990-08-01

    Effects of growth hormone (GH) on the synthesis of mucopolysaccharide by ceratobranchial cartilages of the Japanese eel, Anguilla japonica, were examined by monitoring the in vitro uptake of ({sup 35}S)sulfate. The ({sup 35}S)sulfate uptake decreased rapidly to one-third of the initial level during the first 3 days after hypophysectomy, and decreased gradually thereafter. When hypophysectomized eels were injected intramuscularly with recombinant eel GH (2 micrograms/g), the plasma GH concentrations increased maximally after 6 hr, and declined rapidly thereafter. On the other hand, the sulfate uptake increased significantly after 12 hr, and high levels were maintained until 48 hr. The stimulating effect of GH was dose dependent (0.02-2 micrograms/g). However, the addition of eel GH (0.05-5 micrograms/ml) to the culture medium did not affect the sulfate uptake by hypophysectomized eel cartilages, suggesting that the stimulative action of GH on the sulfate uptake by the cartilages is indirect.

  8. Positivity and Intensity of Gnathostoma spinigerum Infective Larvae in Farmed and Wild-Caught Swamp Eels in Thailand

    PubMed Central

    Saksirisampant, Wilai

    2012-01-01

    From July 2008 to June 2009, livers of the swamp eels (Monopterus alba) were investigated for advanced third-stage larvae (AL3) of Gnathostoma spinigerum. Results revealed that 10.2% (106/1,037) and 20.4% (78/383) of farmed eels from Aranyaprathet District, Sa Kaeo Province and those of wild-caught eels obtained from a market in Min Buri District of Bangkok, Thailand were infected, respectively. The prevalence was high during the rainy and winter seasons. The infection rate abruptly decreased in the beginning of summer. The highest infection rate (13.7%) was observed in September and absence of infection (0%) in March-April in the farmed eels. Whereas, in the wild-caught eels, the highest rate (30.7%) was observed in November, and the rate decreased to the lowest at 6.3% in March. The average no. (mean±SE) of AL3 per investigated liver in farmed eels (1.1±0.2) was significantly lower (P=0.040) than those in the caught eels (0.2±0.03). In addition, the intensity of AL3 recovered from each infected liver varied from 1 to 18 (2.3±0.3) in the farmed eels and from 1 to 47 (6.3±1.2) in the caught eels, respectively. The AL3 intensity showed significant difference (P=0.011) between these 2 different sources of eels. This is the first observation that farmed eels showed positive findings of G. spinigerum infective larvae. This may affect the standard farming of the culture farm and also present a risk of consuming undercooked eels from the wild-caught and farmed eels. PMID:22711921

  9. Temporal and spatial patterns of nestedness in eel macroparasite communities.

    PubMed

    Norton, J; Lewis, J W; Rollinson, D

    2004-08-01

    A nested (non-random) species composition was observed among the intestinal macroparasite communities of European eels, Anguilla anguilla. Nestedness was observed in 8 out of 10 component community samples from the rivers Thames and Test between April 2000 and October 2001. Parasite component communities consisted of mainly generalist and specialist, but also accidental species, and included acanthocephalans, cestodes, nematodes and digeneans. Nestedness was observed when component population size differed markedly between all or most parasite species, but not when the majority of species present was similarly abundant. Nestedness could not be explained in terms of host weight, log normal distribution of parasite species, or mean intensity of infection. It is proposed that nestedness occurred as a result of a sufficiently graded abundance between parasite species, which was established early in the year by colonization processes. PMID:15376779

  10. Examination of subaerially altered basaltic glass with TEM and EELS

    SciTech Connect

    Luo, J.-S.

    1998-06-17

    We have examined the weathered surfaces of 720 year old Hawaiian basalt glasses that were recovered from a subaerial environment with high-resolution transmission electron microscopy (TEM) and energy filtered imaging and electron energy loss spectroscopy (EELS) techniques. Whereas the alteration products (palagonite) were physically detached from the underlying glass in most samples, a gel-like amorphous layer was observed adjacent to the glass in a few samples. To our knowledge, this is the first time a gel layer has been observed on weathered basalt. This is significant because analogous gel layers have been observed on nuclear waste glasses reacted in laboratory tests, and this demonstrates an important similarity in the mechanisms of the weathering of basalt and the corrosion of waste glasses.

  11. Ultrastructure of the adrenocortical homologue in dexamethasone-treated eels.

    PubMed Central

    Bhattacharyya, T K; Butler, D G

    1980-01-01

    The ultrastructural modifications of the adrenocortical homologue (AH) in the North American eel (Anguilla rostrata) were studied following a 10 day treatment with dexamethasone (20 mg/day). The principal changes were: disorganization of smooth endoplasmic reticlum, regression and fragmentation of the Golgi apparatus, and a lowering of matrix density in the mitochondria. Steroid treatment also induced the appearance of numerous cytoplasmic inclusions: (a) lamellated bodies with electron-lucent cores; (b) membranous whorls isolating cytoplasmic regions containing smooth endoplasmic reticulum and mitochondria and (c) complex aggregates showing whorls of membranes, residues of cytoplasmic organelles, and dense matrix. The non-accumulation of lipid droplets in repressed AH cells was noteworthy. These subcellular changes indicate endogenous cellular autophagy in the AH as a result of steroid-induced suppression of ACTH production by the pituitary. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 PMID:7400039

  12. Electric eels use high-voltage to track fast-moving prey

    PubMed Central

    Catania, Kenneth C.

    2015-01-01

    Electric eels (Electrophorus electricus) are legendary for their ability to incapacitate fish, humans, and horses with hundreds of volts of electricity. The function of this output as a weapon has been obvious for centuries but its potential role for electroreception has been overlooked. Here it is shown that electric eels use high-voltage simultaneously as a weapon and for precise and rapid electrolocation of fast-moving prey and conductors. Their speed, accuracy, and high-frequency pulse rate are reminiscent of bats using a ‘terminal feeding buzz' to track insects. Eel's exhibit ‘sensory conflict' when mechanosensory and electrosensory cues are separated, striking first toward mechanosensory cues and later toward conductors. Strikes initiated in the absence of conductors are aborted. In addition to providing new insights into the evolution of strongly electric fish and showing electric eels to be far more sophisticated than previously described, these findings reveal a trait with markedly dichotomous functions. PMID:26485580

  13. Detection of Japanese eel endothelial cells-infecting virus in Anguilla japonica elvers

    PubMed Central

    OKAZAKI, Sachiko; YASUMOTO, Shinya; KOYAMA, Satoshi; TSUCHIAKA, Shinobu; NAOI, Yuki; OMATSU, Tsutomu; ONO, Shin-ichi; MIZUTANI, Tetsuya

    2015-01-01

    Japanese eel endothelial cells-infecting virus (JEECV) has spread in eel farms and caused serious economic loss. In this study, we examined the prevalence of JEECV infection in 100 wild Japanese eel (Anguilla japonica) elvers caught from Yamaguchi prefecture, Japan, using quantitative PCR and conventional PCR. Total genomic DNA was obtained from the cranial quarter of the body in 70 of 100 eels and from the gill in the remaining. Of 30 gill samples, 20 were analyzed after pooling with other samples, and the remaining 10 were analyzed separately. A single positive result for JEECV was detected following analysis of the 10 separately analyzed samples. This result constitutes the first report of JEECV infection in wild A. japonica elvers. PMID:26672624

  14. Detection of Japanese eel endothelial cells-infecting virus in Anguilla japonica elvers.

    PubMed

    Okazaki, Sachiko; Yasumoto, Shinya; Koyama, Satoshi; Tsuchiaka, Shinobu; Naoi, Yuki; Omatsu, Tsutomu; Ono, Shin-Ichi; Mizutani, Tetsuya

    2016-05-01

    Japanese eel endothelial cells-infecting virus (JEECV) has spread in eel farms and caused serious economic loss. In this study, we examined the prevalence of JEECV infection in 100 wild Japanese eel (Anguilla japonica) elvers caught from Yamaguchi prefecture, Japan, using quantitative PCR and conventional PCR. Total genomic DNA was obtained from the cranial quarter of the body in 70 of 100 eels and from the gill in the remaining. Of 30 gill samples, 20 were analyzed after pooling with other samples, and the remaining 10 were analyzed separately. A single positive result for JEECV was detected following analysis of the 10 separately analyzed samples. This result constitutes the first report of JEECV infection in wild A. japonica elvers. PMID:26672624

  15. Micro-PIXE line-scan measurements of the yellow eel's otolith

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Guo, H.; Tang, W.; Wei, K.; Shen, H.; Yang, M.; Mi, Y.

    2011-10-01

    Anguilla japonica has a high economic value. The abundance had decreased significantly due to excessive fishing and change in the aquatic ecology. Life history patterns of A. japonica have been studied to prevent excessive fishing and make management plans. Strontium (Sr)-calcium (Ca) ratio along a line down the long axis from the core to the edge of the yellow eel's otolith was measured using micro proton induced X-ray emission (micro-PIXE). An efficient and precise method was proposed to locate the core where an otolith begins to grow, based on Sr concentration and distribution. Using this method, life history patterns of the yellow eels collected from Jingjiang River in China were investigated. In general, there are two types, river eels and estuarine eels.

  16. The occurrence of organic contaminants in European eel (Anguilla anguilla) in Poland: an environmental quality assessment.

    PubMed

    Szlinder-Richert, Joanna; Ruczynska, Wiesława; Nermer, Tomasz; Usydus, Zygmunt; Robak, Stanisław

    2014-11-01

    The objective of the present study was to provide information on the levels of pollutants in the tissues of eels caught in Polish waters. The contaminants included in the study are those which have not yet been widely studied in eel stocks, but which arouse concern in relation to the environment. An overview of the pollutant levels in eels caught in other European waters was also conducted. The results are evaluated in terms of environmental quality and consumer health. The mean concentrations of ΣPBDEs and ΣHBCDs in muscles of eels sampled in Polish waters were between 1 and 2 ng g(-1) ww. The mean TBT concentrations were between 2 and 4 ng g(-1)ww with the exception of samples from the Szczecin Lagoon, in which the mean TBT concentration was about tenfold higher. PMID:25113214

  17. Mechanism of oocyte maturation and ovulation and its application to seed production in the Japanese eel.

    PubMed

    Kagawa, H; Sakurai, Y; Horiuchi, R; Kazeto, Y; Gen, K; Imaizumi, H; Masuda, Y

    2013-02-01

    Reduction in eel resources and catches of glass eels as seedlings for aquaculture have been a serious concern in recent years in both Europe and East Asia. Thus, technical advancement to produce eel seeds for artificial cultivation is most desired. Fundamental information on oocyte maturation and ovulation and its application to artificial induction of sexual maturation are needed to produce good quality seeds of the Japanese eel. This review introduces hormonal mechanisms of cytoplasmic maturation (such as hydration, lipid coalescence, and clearing of the ooplasm) and the maturational competence (the ability to respond to maturation-inducing steroid) and nuclear maturation (germinal vesicle breakdown). In addition, previous and newly developed methods for induction of spawning have been described. PMID:22278706

  18. Electric eels use high-voltage to track fast-moving prey.

    PubMed

    Catania, Kenneth C

    2015-01-01

    Electric eels (Electrophorus electricus) are legendary for their ability to incapacitate fish, humans, and horses with hundreds of volts of electricity. The function of this output as a weapon has been obvious for centuries but its potential role for electroreception has been overlooked. Here it is shown that electric eels use high-voltage simultaneously as a weapon and for precise and rapid electrolocation of fast-moving prey and conductors. Their speed, accuracy, and high-frequency pulse rate are reminiscent of bats using a 'terminal feeding buzz' to track insects. Eel's exhibit 'sensory conflict' when mechanosensory and electrosensory cues are separated, striking first toward mechanosensory cues and later toward conductors. Strikes initiated in the absence of conductors are aborted. In addition to providing new insights into the evolution of strongly electric fish and showing electric eels to be far more sophisticated than previously described, these findings reveal a trait with markedly dichotomous functions. PMID:26485580

  19. Preservation and Alteration of the 1995 Eel River Flood Deposit

    NASA Astrophysics Data System (ADS)

    Richey, C. A.; Bodenhamer, C.; Borgeld, J. C.; Brower, J.; Genger, H. M.; Hayduk, L. A.; Ryan, T. W.; Slimmer, M. D.; Westman, V.

    2004-12-01

    The Eel River shelf of northern California is episodically subject to seasonal flood events and associated sediment deposition. Flooding of the Eel River in the winter and spring of 1995, and the winter of 1997, resulted in a recognizable sequence of layers deposited across much of the adjacent continental shelf. Event-response sampling allowed the short term fate of the deposits to be documented (Wheatcroft, 2000). Within a few years after the 1997 event, the flood deposit was mixed or remobilized such that the original deposit was not recognized in core x-radiographs anywhere on the shelf. However, remnants of the 1995 flood deposit were still identifiable as of October 2001 (Wheatcroft et al., in progress). In May 2004, a total of 31 box cores were collected at 23 different stations along transects established by previous studies. Flood layers were still present and recognizable in x-radiographs at several stations. Many of the layers identified in x-radiographs were, although preserved, visibly disrupted. In locations where x-radiographs were inconclusive, the unusually fine-grained nature of the deposit allowed them to be detected using standard sediment size analyses. The mean percent of sediment <20 μ m ranged from 68-84% in the 1995 flood deposit. Core subsamples were analyzed from the upper 16 cm in order to determine biological abundance. Polychaete worms were identified as the dominant taxonomic group, constituting approximately 80% of the identified organisms, which is consistent with previous research (Wheatcroft et al., in progress; Bentley and Nittrouer, 2003). The dominance of polychaetes is notable in light of the fact that these subsurface deposit feeders are likely to mix sediment to substantial depths (Wheatcroft et al., in progress). Despite this biological activity, the flood layer is still recognizable a decade after the initial event. As a result, the 1995 flood deposit may ultimately become a permanent piece of the stratigraphic record.

  20. Individual and combined effects of copper and parasitism on osmoregulation in the European eel Anguilla anguilla.

    PubMed

    Lorin-Nebel, Catherine; Felten, Vincent; Blondeau-Bidet, Eva; Grousset, Evelyse; Amilhat, Elsa; Simon, Gael; Biagianti, Sylvie; Charmantier, Guy

    2013-04-15

    The European eel (Anguilla anguilla), a catadromous species, breeds in the sea and migrates to estuarine, lagoon or freshwater habitats for growth and development. Yellow eels, exposed to low or fluctuating salinities, are also exposed to multiple other stressors as pollution, over-fishing and parasitism, which contribute to the dramatic decrease of eel populations in several European countries. The objective of this study was to evaluate the single and combined effects of waterborne copper and experimental infestation of eels with the nematode Anguillicoloides crassus after a salinity challenge from nearly isotonic (18ppt) to hypo- (5ppt) and hypertonic (29ppt) conditions, in order to investigate the osmoregulatory capacity of eels exposed to these stressors. In a nearly isotonic condition (18ppt), blood osmolality remained constant over the 6 weeks contamination to Cu(2+) and Anguillicoloides crassus. In fish exposed to a salinity challenge of 29ppt for 2 weeks, no significant effect was recorded in blood osmolality, Na(+)/K(+)-ATPase (NKA) activity, Na(+) and Cl(-) concentrations. After 2 weeks at 5ppt however, a significant blood osmolality decrease was detected in fish exposed to Anguillicoloides crassus infestation with or without Cu(2+) addition. This decrease may originate from lower Cl(-) levels measured in eels exposed to both stressors. Blood Na(+) levels remained relatively stable in all tested animals, but gill NKA activities were lower in eels exposed to combined stress. No apparent branchial lesions were detected following the different treatments and immunolocalization of NKA revealed well-differentiated ionocytes. Thus, the 5ppt challenge in eels exposed to copper and Anguillicoloides crassus seems to clearly enhance iono/osmoregulatory disturbances. Funded by ANR CES/CIEL 2008-12. PMID:23340332

  1. The Giant Mottled Eel, Anguilla marmorata, Uses Blue-Shifted Rod Photoreceptors during Upstream Migration

    PubMed Central

    Wang, Feng-Yu; Fu, Wen-Chun; Wang, I-Li

    2014-01-01

    Catadromous fishes migrate between ocean and freshwater during particular phases of their life cycle. The dramatic environmental changes shape their physiological features, e.g. visual sensitivity, olfactory ability, and salinity tolerance. Anguilla marmorata, a catadromous eel, migrates upstream on dark nights, following the lunar cycle. Such behavior may be correlated with ontogenetic changes in sensory systems. Therefore, this study was designed to identify changes in spectral sensitivity and opsin gene expression of A. marmorata during upstream migration. Microspectrophotometry analysis revealed that the tropical eel possesses a duplex retina with rod and cone photoreceptors. The λmax of rod cells are 493, 489, and 489 nm in glass, yellow, and wild eels, while those of cone cells are 508, and 517 nm in yellow, and wild eels, respectively. Unlike European and American eels, Asian eels exhibited a blue-shifted pattern of rod photoreceptors during upstream migration. Quantitative gene expression analyses of four cloned opsin genes (Rh1f, Rh1d, Rh2, and SWS2) revealed that Rh1f expression is dominant at all three stages, while Rh1d is expressed only in older yellow eel. Furthermore, sequence comparison and protein modeling studies implied that a blue shift in Rh1d opsin may be induced by two known (N83, S292) and four putative (S124, V189, V286, I290) tuning sites adjacent to the retinal binding sites. Finally, expression of blue-shifted Rh1d opsin resulted in a spectral shift in rod photoreceptors. Our observations indicate that the giant mottled eel is color-blind, and its blue-shifted scotopic vision may influence its upstream migration behavior and habitat choice. PMID:25101636

  2. Low PCB concentrations observed in American eel (Anguilla rostrata) in six Hudson River tributaries

    USGS Publications Warehouse

    Limburg, K.E.; Machut, L.S.; Jeffers, P.; Schmidt, R.E.

    2008-01-01

    We analyzed 73 eels, collected in 2004 and 2005 above the head of tide in six Hudson River tributaries, for total PCBs, length, weight, age, and nitrogen stable isotope ratios (??15N). Mean total PCB concentration (wet weight basis) was 0.23 ppm ?? 0.08 (standard error), with a range of 0.008 to 5.4 ppm. A majority of eels (84) had concentrations below 0.25 ppm, and only seven eels (10%) had concentrations exceeding 0.5 ppm. Those eels with higher PCB concentrations were ???12 yr; there was a weak correlation of PCB concentration with ??15N and also with weight. Compared to recent (2003) data from the mainstem of the Hudson River estuary, these results indicate that tributaries are generally much less contaminated with PCBs. We hypothesize that those tributary eels with high PCB concentrations were relatively recent immigrants from the mainstem. Given concern over the possible adverse effects of PCBs on eel reproduction, these tributaries may serve as refugia. Therefore, providing improved access to upland tributaries may be critically important to this species. ?? 2008 Northeastern Naturalist.

  3. Heterogeneity among Isolates of Vibrio vulnificus Recovered from Eels (Anguilla anguilla) in Denmark

    PubMed Central

    Høi, Lise; Dalsgaard, Inger; DePaola, Angelo; Siebeling, Ronald J.; Dalsgaard, Anders

    1998-01-01

    The findings of this study demonstrate that Vibrio vulnificus isolates recovered from diseased eels in Denmark are heterogeneous as shown by O serovars, capsule types, ribotyping, phage typing, and plasmid profiling. The study includes 85 V. vulnificus isolates isolated from the gills, intestinal contents, mucus, spleen, and kidneys of eels during five disease outbreaks on two Danish eel farms from 1995 to 1997, along with a collection of 12 V. vulnificus reference strains. The results showed that more than one serovar may be capable of causing disease in eels and that these isolates are genetically heterogenous as shown by ribotyping. Ribotyping also showed that the same isolates may persist in an eel farm and cause recurrent outbreaks. Phage typing did not correlate with ribotyping or serotyping. However, we observed that 26 of 28 isolates, which were not susceptible to any of the phages, showed the same ribotype, O serovar, and capsule type. This suggests that these isolates may possess features that make them resistant to lysis by the phages used in this study. Ninety-three of 97 isolates harbored between one and three high-molecular-weight plasmids which previously had been suggested to be associated with eel virulence. The subdivision of V. vulnificus into two biotypes based on the indole reaction can no longer be supported, since 82 of 97 isolates in this study were indole positive, and a subdivision into serovars appears to be more correct. PMID:9835548

  4. A 'living fossil' eel (Anguilliformes: Protanguillidae, fam. nov.) from an undersea cave in Palau.

    PubMed

    Johnson, G David; Ida, Hitoshi; Sakaue, Jiro; Sado, Tetsuya; Asahida, Takashi; Miya, Masaki

    2012-03-01

    We report the discovery of an enigmatic, small eel-like fish from a 35 m-deep fringing-reef cave in the western Pacific Ocean Republic of Palau that exhibits an unusual suite of morphological characters. Many of these uniquely characterize the Recent members of the 19 families comprising the elopomorph order Anguilliformes, the true eels. Others are found among anguilliforms only in the Cretaceous fossils, and still others are primitive with respect to both Recent and fossil eels. Thus, morphological evidence explicitly places it as the most basal lineage (i.e. the sister group of extant anguilliforms). Phylogenetic analysis and divergence time estimation based on whole mitogenome sequences from various actinopterygians, including representatives of all eel families, demonstrate that this fish represents one of the most basal, independent lineages of the true eels, with a long evolutionary history comparable to that of the entire Anguilliformes (approx. 200 Myr). Such a long, independent evolutionary history dating back to the early Mesozoic and a retention of primitive morphological features (e.g. the presence of a premaxilla, metapterygoid, free symplectic, gill rakers, pseudobranch and distinct caudal fin rays) warrant recognition of this species as a 'living fossil' of the true eels, herein described as Protanguilla palau genus et species nov. in the new family Protanguillidae. PMID:21849321

  5. A ‘living fossil’ eel (Anguilliformes: Protanguillidae, fam. nov.) from an undersea cave in Palau

    PubMed Central

    Johnson, G. David; Ida, Hitoshi; Sakaue, Jiro; Sado, Tetsuya; Asahida, Takashi; Miya, Masaki

    2012-01-01

    We report the discovery of an enigmatic, small eel-like fish from a 35 m-deep fringing-reef cave in the western Pacific Ocean Republic of Palau that exhibits an unusual suite of morphological characters. Many of these uniquely characterize the Recent members of the 19 families comprising the elopomorph order Anguilliformes, the true eels. Others are found among anguilliforms only in the Cretaceous fossils, and still others are primitive with respect to both Recent and fossil eels. Thus, morphological evidence explicitly places it as the most basal lineage (i.e. the sister group of extant anguilliforms). Phylogenetic analysis and divergence time estimation based on whole mitogenome sequences from various actinopterygians, including representatives of all eel families, demonstrate that this fish represents one of the most basal, independent lineages of the true eels, with a long evolutionary history comparable to that of the entire Anguilliformes (approx. 200 Myr). Such a long, independent evolutionary history dating back to the early Mesozoic and a retention of primitive morphological features (e.g. the presence of a premaxilla, metapterygoid, free symplectic, gill rakers, pseudobranch and distinct caudal fin rays) warrant recognition of this species as a ‘living fossil’ of the true eels, herein described as Protanguilla palau genus et species nov. in the new family Protanguillidae. PMID:21849321

  6. Isolation of heat-tolerant myoglobin from Asian swamp eel Monopterus albus.

    PubMed

    Chotichayapong, Chatrachatchaya; Wiengsamut, Kittipong; Chanthai, Saksit; Sattayasai, Nison; Tamiya, Toru; Kanzawa, Nobuyuki; Tsuchiya, Takahide

    2012-10-01

    Myoglobin from Asian swamp eel Monopterus albus was purified from fish muscle using salt fractionation followed by column chromatography and molecular filtration. The purified Mb of 0.68 mg/g wet weight of muscle was determined for its molecular mass by MALDI-TOF-MS to be 15,525.18 Da. Using isoelectric focusing technique, the purified Mb showed two derivatives with pI of 6.40 and 7.12. Six peptide fragments of this protein identified by LC-MS/MS were homologous to Mbs of sea raven Hemitripterus americanus, yellowfin tuna Thunnus albacores, blue marlin Makaira nigicans, common carp Cyprinus carpio, and goldfish Carassius auratus. According to the Mb denaturation, the swamp eel Mb had thermal stability higher than walking catfish Clarias batrachus Mb and striped catfish Pangasius hypophthalmus Mb, between 30 and 60 (°)C. For the thermal stability of Mb, the swamp eel Mb showed a biphasic behavior due to the O(2) dissociation and the heme orientation disorder, with the lowest increase in both Kd(f) and Kd(s). The thermal sensitivity of swamp eel Mb was lower than those of the other Mbs for both of fast and slow reaction stages. These results suggest that the swamp eel Mb globin structure is thermally stable, which is consistent with heat-tolerant behavior of the swamp eel particularly in drought habitat. PMID:22538454

  7. Distribution and abundance of American eels in the White Oak River estuary, North Carolina

    USGS Publications Warehouse

    Hightower, J.E.; Nesnow, C.

    2006-01-01

    Apparent widespread declines in abundance of Anguilla rostrata (American eel) have reinforced the need for information regarding its life history and status. We used commercial eel pots and crab (peeler) pots to examine the distribution, condition, and abundance of American eels within the White Oak River estuary, NC, during summers of 2002-2003. Catch of American eels per overnight set was 0.35 (SE = 0.045) in 2002 and 0.49 (SE = 0.044) in 2003. There was not a significant linear relationship between catch per set and depth in 2002 (P = 0.31, depth range 0.9-3.4 m) or 2003 (P = 0.18, depth range 0.6-3.4 m). American eels from the White Oak River were in good condition, based on the slope of a length-weight relationship (3.41) compared to the median slope (3.15) from other systems. Estimates of population density from grid sampling in 2003 (300 mm and larger: 4.0-13.8 per ha) were similar to estimates for the Hudson River estuary, but substantially less than estimates from other (smaller) systems including tidal creeks within estuaries. Density estimates from coastal waters can be used with harvest records to examine whether overfishing has contributed to the recent apparent declines in American eel abundance.

  8. Seasonality of spawning by tropical anguillid eels around Sulawesi Island, Indonesia.

    PubMed

    Wouthuyzen, Sam; Aoyama, Jun; Sugeha, H Yulia; Miller, Michael J; Kuroki, Mari; Minegishi, Yuki; Suharti, Sasanti R; Tsukamoto, Katsumi

    2009-01-01

    Remarkably little is known about the life histories of the many tropical anguillid eels distributed across the Indo-Pacific region, and since the Danish expedition to study eels in the region in 1928 and 1929, research on these eels has only begun again in recent years. Sampling for anguillid leptocephali in the Indonesian Seas has been carried out recently to learn about the spawning ecology and larval distributions of tropical eels there. The leptocephali of Anguilla marmorata, Anguilla bicolor pacifica, Anguilla borneensis, Anguilla interioris, and Anguilla celebesensis were collected around Sulawesi Island both in May 2001 and October of 2002. The development of genetic identification techniques has enabled these leptocephali to be identified to species, and their distributions and sizes during different seasons indicated that there are differing life history patterns among sympatric species in the region. A. celebesensis was found to have been spawning in Tomini Bay of northeastern Sulawesi Island in March and April 2001, but apparently, no spawning had occurred in the late summer and fall of 2002. Studies on anguillid glass eels have suggested that tropical anguillids may spawn throughout much of year, but our research on leptocephali in Tomini Bay and data on the downstream migration of tropical anguillids in the major tributary to Tomini Bay indicate that A. celebesensis may have a distinct seasonal pattern of spawning possibly related to the regional monsoon cycles. This is the first evidence of seasonality of spawning in tropical anguillid eels whose life histories are only just beginning to be revealed. PMID:18850081

  9. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (South Atlantic). American eel

    SciTech Connect

    Van Den Avyle, M.J.

    1984-07-01

    The American eel, Anguilla rostrata, is an ecologically and economically important catadromous species that occupies freshwater streams, rivers, brackish estuaries, and the open ocean during various phases of its life cycle. Adult eels apparently spawn in the Sargasso Sea, and ocean currents transport the developing larvae northward until the young metamorphose into juveniles capable of swimming shoreward and moving upstream into coastal areas, estuaries, and rivers. Developing eels commonly remain in freshwater or brackish area for 10 to 12 years before migrating to spawn. American eels tend to be bottom-dwellers and feed on a variety of fauna that occupy the same habitats. Eels occupy areas having wide ranges of temperature, salinity, and other environmental factors, suggesting broad tolerance limits, but few studies of requirements have been reported. Salinity patterns and water currents created by river discharges into coastal areas apparently provide the gradient that cues shoreward migration of juvenile eels. Alteration of patterns of freshwater inflows to estuaries and bays could affect upstream migrations. 73 references, 3 figures, 1 table.

  10. A telephone survey of eel fishermen regarding external lesions and mortalities of American eels (Anguilla rostrata) from Lake Ontario and the St. Lawrence River basin, Canada.

    PubMed

    Dutil, L; Bélanger, D; Couillard, C M

    1997-07-01

    Signs of decreasing landings and recruitment have been observed during the last decade in American eels (Anguilla rostrata) from the St. Lawrence River basin, Canada. A study was undertaken to examine whether important manifestational diseases among commercial catches could be associated with these declines. During this survey, 56 fishermen from Lakes Ontario, Saint-François and Saint-Pierre, the Richelieu River, the Québec City area and the St. Lawrence Estuary were interviewed. Most fishermen from every area reported decreasing catches since the 1980s. Eel mortalities were reported from 1990 to 1992 in Lake Saint-François, Lake Saint-Pierre and the Québec City area, but in apparently lower magnitude than in the past decades. The lesions observed on dead eels in Lake Saint-François indicated that the cause of the mortalities might be associated with the upstream hydroelectric dam. Eels with 'scratches all over the body' were only observed in the St. Lawrence Estuary. Fishermen from almost every area reported that they had observed eels with 'crooked tail', 'humpback' and 'cut tail' in low frequency in 1992. The questionnaire data were validated by comparing some of the results of the questionnaire survey and a processing plant survey in 1992. The use of questionnaires for assessing fish diseases in commercial species is discussed. The results of this survey do not indicate that the health of the American eels from the St. Lawrence River basin is severely impaired. However, the magnitude of diseases and mortalities was probably underestimated. PMID:9234424

  11. Silver and Gold NMR

    PubMed Central

    Zangger, Klaus

    1999-01-01

    Silver and gold, together with copper, form the transition metal group IB elements in the periodic table and possess very different nuclear magnetic resonance (NMR) spectroscopic properties. While there is only one gold isotope (197Au), which has a spin of 3/2 and therefore a quadrupole moment, silver occurs in two isotopic forms (109Ag and 109Au), both of which have a spin 1/2 and similar NMR spectroscopic properties. The unfavorable properties of gold have prevented its NMR spectroscopic investigation thus far. On the other hand, there are several reports of silver NMR. However, the low sensitivity of silver, combined with its long relaxation times have rendered the direct detection of silver possible only with concentrations greater than a few tenth molar. Reviewed here are the general limitations of silver NMR and some techniques to partially overcome these limitations, as well as a summary of currently available chemical shift and scalar coupling data on 109Ag. PMID:18475898

  12. Genetics Home Reference: Silver syndrome

    MedlinePlus

    ... Me Understand Genetics Home Health Conditions Silver syndrome Silver syndrome Enable Javascript to view the expand/collapse boxes. Download PDF Open All Close All Description Silver syndrome belongs to a group of genetic disorders ...

  13. Effect of multipole excitations in electron energy-loss spectroscopy of surface plasmon modes in silver nanowires

    SciTech Connect

    Zhou, Xiuli; Norris, Theodore B.; Hörl, Anton; Trügler, Andreas; Hohenester, Ulrich; Herzing, Andrew A.

    2014-12-14

    We have characterized the surface plasmon resonance (SPR) in silver nanowires using spatially resolved electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope. Non-symmetric EELS spectra due to high-k SPR propagation along the nanowire and spectral shifts due to higher-order mode excitation are observed when the beam is positioned near the tip of the nanowire. When the beam is far from the tip region and on the side of nanowire, no spectral shifts are observed as the beam is scanned in the radial direction of the nanowire. The experimental spectra are compared with three different theoretical approaches: direct numerical calculation of the energy loss, analytical models for energy loss, and numerical simulations using an optical model. All three models reproduce the spectral shifts as the electron beam approaches the cap of the nanowire. The analytical model reveals the origin of the shifts in high-order plasmon mode excitation.

  14. Dosimetry using silver salts

    DOEpatents

    Warner, Benjamin P.

    2003-06-24

    The present invention provides a method for detecting ionizing radiation. Exposure of silver salt AgX to ionizing radiation results in the partial reduction of the salt to a mixture of silver salt and silver metal. The mixture is further reduced by a reducing agent, which causes the production of acid (HX) and the oxidized form of the reducing agent (R). Detection of HX indicates that the silver salt has been exposed to ionizing radiation. The oxidized form of the reducing agent (R) may also be detected. The invention also includes dosimeters employing the above method for detecting ionizing radiation.

  15. The silver ions contribution into the cytotoxic activity of silver and silver halides nanoparticles

    NASA Astrophysics Data System (ADS)

    Klimov, A. I.; Zherebin, P. M.; Gusev, A. A.; Kudrinskiy, A. A.; Krutyakov, Y. A.

    2015-11-01

    The biocidal action of silver nanoparticles capped with sodium citrate and silver halides nanoparticles capped with non-ionic surfactant polyoxyethylene(20)sorbitan monooleate (Tween 80®) against yeast cells Saccharomyces cerevisiae was compared to the effect produced by silver nitrate and studied through the measurement of cell loss and kinetics of K+ efflux from the cells. The cytotoxicity of the obtained colloids was strongly correlated with silver ion content in the dispersions. The results clearly indicated that silver and silver halides nanoparticles destroyed yeast cells through the intermediate producing of silver ions either by dissolving of salts or by oxidation of silver.

  16. An Enriched European Eel Transcriptome Sheds Light upon Host-Pathogen Interactions with Vibrio vulnificus

    PubMed Central

    Callol, Agnès; Reyes-López, Felipe E.; Roig, Francisco J.; Goetz, Giles; Goetz, Frederick W.; Amaro, Carmen; MacKenzie, Simon A.

    2015-01-01

    Infectious diseases are one of the principal bottlenecks for the European eel recovery. The aim of this study was to develop a new molecular tool to be used in host-pathogen interaction experiments in the eel. To this end, we first stimulated adult eels with different pathogen-associated molecular patterns (PAMPs), extracted RNA from the immune-related tissues and sequenced the transcriptome. We obtained more than 2x106 reads that were assembled and annotated into 45,067 new descriptions with a notable representation of novel transcripts related with pathogen recognition, signal transduction and the immune response. Then, we designed a DNA-microarray that was used to analyze the early immune response against Vibrio vulnificus, a septicemic pathogen that uses the gills as the portal of entry into the blood, as well as the role of the main toxin of this species (RtxA13) on this early interaction. The gill transcriptomic profiles obtained after bath infecting eels with the wild type strain or with a mutant deficient in rtxA13 were analyzed and compared. Results demonstrate that eels react rapidly and locally against the pathogen and that this immune-response is rtxA13-dependent as transcripts related with cell destruction were highly up-regulated only in the gills from eels infected with the wild-type strain. Furthermore, significant differences in the immune response against the wild type and the mutant strain also suggest that host survival after V. vulnificus infection could depend on an efficient local phagocytic activity. Finally, we also found evidence of the presence of an interbranchial lymphoid tissue in European eel gills although further experiments will be necessary to identify such tissue. PMID:26207370

  17. The Silver Bullet Syndrome.

    ERIC Educational Resources Information Center

    Dehne, George C.

    1995-01-01

    Many colleges address complex problems with a single "silver bullet" strategy. Because value shifts according to the consumer's situation or goal, private colleges should become more aware of their "situational value" and exploit it. This requires an understanding of how students choose colleges. In contrast, popular silver bullets target…

  18. Comparison of swimming capacity and energetics of migratory European eel (Anguilla anguilla) and New Zealand short-finned eel (A. australis)

    PubMed Central

    Tudorache, Christian; Burgerhout, Erik; Brittijn, Sebastiaan; van den Thillart, Guido

    2015-01-01

    The spawning migration of the European eel (Anguilla anguilla) can cover more than 6000 km, while that of the New Zealand short-finned eel (A. australis) is assumed to be approximately 3000 km. Since these species are expected to show adaptive traits to such an important lifetime event, we hypothesized differences in swimming capacity and energetics as a response to this adaptation. In an experimental swimming respirometer set-up, critical swimming speed (Ucrit), optimal swimming speed (Uopt), mass specific oxygen consumption rate (ṀO2), standard metabolic rate (SMR), active metabolic rate at Ucrit (AMRcrit) and at Uopt (AMRopt), the minimum cost of transport at Uopt (COTmin), and the scope for activity, were assessed and compared between the species. With a similar body length and mass, European eels showed ca. 25% higher values for both Ucrit and Uopt, and 23% lower values for COTmin, compared to New Zealand short-finned eels. However, SMR, AMRcrit, AMRopt, and scope for activity did not differ between the species, indicating very similar swimming physiology traits. This study discusses physiological aspects of long distance migration and provides recommendations for (a) swimming respirometry in anguilliform fish, and (b) telemetry research using externally attached pop-up tags. PMID:26441675

  19. RAD sequencing highlights polygenic discrimination of habitat ecotypes in the panmictic American eel.

    PubMed

    Pavey, Scott A; Gaudin, Jérémy; Normandeau, Eric; Dionne, Mélanie; Castonguay, Martin; Audet, Céline; Bernatchez, Louis

    2015-06-15

    The two primary ways that species respond to heterogeneous environments is through local adaptation and phenotypic plasticity. The American eel (Anguilla rostrata) presents a paradox; despite inhabiting drastically different environments [1], the species is panmictic [2, 3]. Spawning takes place only in the southern Sargasso Sea in the Atlantic Ocean [1]. Then, the planktonic larvae (leptocephali) disperse to rearing locations from Cuba to Greenland, and juveniles colonize either freshwater or brackish/saltwater habitats, where they spend 3-25 years before returning to the Sargasso Sea to spawn as a panmictic species. Depending on rearing habitat, individuals exhibit drastically different ecotypes [4-6]. In particular, individuals rearing in freshwater tend to grow slowly and mature older and are more likely to be female in comparison to individuals that rear in brackish/saltwater [4, 6]. The hypothesis that phenotypic plasticity alone can account for all of the differences was not supported by three independent controlled experiments [7-10]. Here, we present a genome-wide association study that demonstrates a polygenic basis that discriminates these habitat-specific ecotypes belonging to the same panmictic population. We found that 331 co-varying loci out of 42,424 initially considered were associated with the divergent ecotypes, allowing a reclassification of 89.6%. These 331 SNPs are associated with 101 genes that represent vascular and morphological development, calcium ion regulation, growth and transcription factors, and olfactory receptors. Our results are consistent with divergent natural selection of phenotypes and/or genotype-dependent habitat choice by individuals that results in these genetic differences between habitats, occurring every generation anew in this panmictic species. PMID:26028437

  20. Method for the recovery of silver from silver zeolite

    DOEpatents

    Reimann, G.A.

    1985-03-05

    High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

  1. Method for the recovery of silver from silver zeolite

    SciTech Connect

    Reimann, George A.

    1986-01-01

    High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

  2. Coupling EELS/EFTEM Imaging with Environmental Fluid Cell Microscopy

    SciTech Connect

    Unocic, Raymond R; Baggetto, Loic; Veith, Gabriel M; Dudney, Nancy J; More, Karren Leslie

    2012-01-01

    Insight into dynamically evolving electrochemical reactions and mechanisms encountered in electrical energy storage (EES) and conversion technologies (batteries, fuel cells, and supercapacitors), materials science (corrosion and oxidation), and materials synthesis (electrodeposition) remains limited due to the present lack of in situ high-resolution characterization methodologies. Electrochemical fluid cell microscopy is an emerging in-situ method that allows for the direct, real-time imaging of electrochemical processes within a fluid environment. This technique is facilitated by the use of MEMS-based biasing microchip platforms that serve the purpose of sealing the highly volatile electrolyte between two electron transparent SiNx membranes and interfacing electrodes to an external potentiostat for controlled nanoscale electrochemislly experiments [!]. In order to elucidate both stmctural and chemical changes during such in situ electrochemical experiments, it is impmtant to first improve upon the spatial resolution by utilizing energy-filtered transmission electron microscopy (EFTEM) (to minimize chromatic aben ation), then to detennine the chemical changes via electron energy loss spectroscopy (EELS). This presents a formidable challenge since the overall thickness through which electrons are scattered through the multiple layers of the cell can be on the order of hundreds of nanometers to microns, scattering through which has the deleterious effect of degrading image resolution and decreasing signal-to noise for spectroscopy [2].

  3. Eel calcitonin binding site distribution and antinociceptive activity in rats

    SciTech Connect

    Guidobono, F.; Netti, C.; Sibilia, V.; Villa, I.; Zamboni, A.; Pecile, A.

    1986-03-01

    The distribution of binding site for (/sup 125/I)-eel-calcitonin (ECT) to rat central nervous system, studied by an autoradiographic technique, showed concentrations of binding in the diencephalon, the brain stem and the spinal cord. Large accumulations of grains were seen in the hypothalamus, the amygdala, in the fasciculus medialis prosencephali, in the fasciculus longitudinalis medialis, in the ventrolateral part of the periventricular gray matter, in the lemniscus medialis and in the raphe nuclei. The density of grains in the reticular formation and in the nucleus tractus spinalis nervi trigemini was more moderate. In the spinal cord, grains were scattered throughout the dorsal horns. Binding of the ligand was displaced equally by cold ECT and by salmon CT(sCT), indicating that both peptides bind to the same receptors. Human CT was much weaker than sCT in displacing (/sup 125/I)-ECT binding. The administration of ECT into the brain ventricles of rats dose-dependently induced a significant and long-lasting enhancement of hot-plate latencies comparable with that obtained with sCT. The antinociceptive activity induced by ECT is compatible with the topographical distribution of binding sites for the peptide and is a further indication that fish CTs are active in the mammalian brain.

  4. Silver(II) Oxide or Silver(I,III) Oxide?

    ERIC Educational Resources Information Center

    Tudela, David

    2008-01-01

    The often called silver peroxide and silver(II) oxide, AgO or Ag[subscript 2]O[subscript 2], is actually a mixed oxidation state silver(I,III) oxide. A thermochemical cycle, with lattice energies calculated within the "volume-based" thermodynamic approach, explain why the silver(I,III) oxide is more stable than the hypothetical silver(II) oxide.…

  5. Gene transcription reflects poor health status of resident European eel chronically exposed to environmental pollutants.

    PubMed

    Maes, G E; Raeymaekers, J A M; Hellemans, B; Geeraerts, C; Parmentier, K; De Temmerman, L; Volckaert, F A M; Belpaire, C

    2013-01-15

    Understanding the effects of chronic exposure to pollutants on the genome and transcriptome of diadromous fish populations is crucial for their resilience under combined anthropogenic and environmental selective pressures. The catadromous European eel (Anguilla anguilla L.) has suffered a dramatic decline in recruitment for three decades, necessitating a thorough assessment of the transcriptional effects of environmental pollutants on resident and migrating eels in natural systems. We investigated the relationship between muscular bioaccumulation levels of metals (Hg, Cd, Pb, Cu, Zn, Ni, Cr, As and Se), PCBs and organochlorine pesticides (DDTs), the health status (condition factor and lipid reserves) and the associated transcriptional response in liver and gill tissues for genes involved in metal detoxification (metallothionein, MT) and oxidative metabolism (cytochrome P4501A, CYP1A) of xenobiotic compounds. In total 84 resident eels originating from three Belgian river basins (Scheldt, Meuse and Yzer) were analyzed along with five unpolluted aquaculture samples as control group. There was a large spatial variation in individual contaminant intensity and profile, while tissue pollution levels were strongly and negatively associated with condition indices, suggesting an important impact of pollution on the health of sub-adult resident eels. Gene transcription patterns revealed a complex response mechanism to a cocktail of pollutants, with a high variation at low pollution levels, but strongly down-regulated hepatic and gill gene transcription in highly polluted eels. Resident eels clearly experience a high pollution burden and seem to show a dysfunctional gene transcription regulation of detoxification genes at higher pollutant levels, correlated with low energy reserves and condition. To fully understand the evolutionary implications of pollutants on eel reproductive fitness, analyses of mature migrating eels and the characterization of their transcriptome

  6. Mineral commodity profiles: Silver

    USGS Publications Warehouse

    Butterman, W.C.; Hilliard, Henry E.

    2005-01-01

    Overview -- Silver is one of the eight precious, or noble, metals; the others are gold and the six platinum-group metals (PGM). World mine production in 2001 was 18,700 metric tons (t) and came from mines in 60 countries; the 10 leading producing countries accounted for 86 percent of the total. The largest producer was Mexico, followed by Peru, Australia, and the United States. About 25 percent of the silver mined in the world in 2001 came from silver ores; 15 percent, from gold ores and the remaining 60 percent, from copper, lead, and zinc ores. In the United States, 14 percent of the silver mined in 2001 came from silver ores; 39 percent, from gold ores; 10 percent, from copper and copper-molybdenum ores; and 37 percent, from lead, zinc, and lead-zinc ores. The precious metal ores (gold and silver) came from 30 lode mines and 10 placer mines; the base-metal ores (copper, lead, molybdenum, and zinc) came from 24 lode mines. Placer mines yielded less than 1 percent of the national silver production. Silver was mined in 12 States, of which Nevada was by far the largest producer; it accounted for nearly one-third of the national total. The production of silver at domestic mines generated employment for about 1,100 mine and mill workers. The value of mined domestic silver was estimated to be $290 million. Of the nearly 27,000 t of world silver that was fabricated in 2001, about one-third went into jewelry and silverware, one-fourth into the light-sensitive compounds used in photography, and nearly all the remainder went for industrial uses, of which there were 7 substantial uses and many other small-volume uses. By comparison, 85 percent of the silver used in the United States went to photography and industrial uses, 8 percent to jewelry and silverware, and 7 percent to coins and medals. The United States was the largest consumer of silver followed by India, Japan, and Italy; the 13 largest consuming countries accounted for nearly 90 percent of the world total. In the

  7. Phthalate metabolites in the European eel (Anguilla anguilla) from Mediterranean coastal lagoons.

    PubMed

    Fourgous, C; Chevreuil, M; Alliot, F; Amilhat, E; Faliex, E; Paris-Palacios, S; Teil, M J; Goutte, A

    2016-11-01

    The levels and fate of phthalate metabolites have been poorly evaluated in fish, despite their potential ecotoxicological impacts. The present study aims to characterize the levels of phthalate metabolites in muscle tissue of yellow eels (Anguilla anguilla) from two coastal Mediterranean lagoons, during three sampling periods. Nine phthalate metabolites were detected in >70% of the samples. Slightly higher levels of phthalate metabolites were detected in March and June compared to October, suggesting possible seasonal variations in environmental release and/or phthalate metabolization process by eels. The large sample size (N=117) made it possible to explore correlations between phthalate metabolites' levels and individual parameters, such as body length, age, body condition and hepatic histo-pathologies. Body length and estimated age poorly correlated with phthalate metabolites, suggesting that eels did not accumulate phthalates during growth, contrary to persistent compounds. Eels presented different grades of hepatic fibrosis and lipidosis. A negative correlation was found between the severity of these pathologies in the liver and the sum of phthalate metabolites levels, supporting the hypothesis that eels with damaged liver are less able to metabolize xenobiotics. PMID:27412480

  8. Epidemiology and pathology of Anguillicoloides crassus in European eel Anguilla anguilla from the Tagus estuary (Portugal).

    PubMed

    Neto, Ana Filipa; Costa, José Lino; Costa, Maria José; Domingos, Isabel

    2010-02-17

    Infection of the European eel Anguilla anguilla by the swimbladder nematode Anguillicoloides crassus was investigated for the first time at 5 sampling sites in the Tagus estuary (Portugal). A total of 332 yellow eels were examined, revealing a prevalence of 56% and a mean intensity of 3.2 lumen worms per swimbladder. The effect of the host's sex and size on parasitism descriptors was studied. Only total length (TL) was considered a significant determinant, with larger eels harbouring a higher number of nematodes. Eels were parasitized in 4 of the 5 sampling sites, with prevalence values following the salinity gradient along the Tagus estuary. No signs of the nematode were observed in the most saline site. Variations in the intensity of infection were only apparent when a large geographic scale including a wide temperature range was considered. Although 68% of the analysed eels showed pathological damage to the swimbladder caused by the parasite, injuries were relatively reduced in comparison with other studies. No effect of the infection on the condition of the body and on liver condition was detected. However, considerable spleen enlargement was observed with increasing parasite load, which could be related to the bloodsucking activity of this nematode. PMID:20377012

  9. Isolation and molecular characterization of herpesvirus from cultured European eels Anguilla anguilla in Taiwan.

    PubMed

    Chang, Pen Heng; Pan, Yie Hour; Wu, Chein Ming; Kuo, Shu Ting; Chung, Huu Yun

    2002-07-01

    A herpesvirus has been isolated for the first time from a population of European eels Anguilla anguilla cultured in a recirculated system in Taiwan. Syncytia formation was detected in EP-1 (eel epidermis) cell cultures inoculated with cell-free homogenates prepared from both integument and visceral organs of moribund fish. Inoculation of homogenates onto EK (eel kidney) cell cultures induced giant cell formation. Subsequent passages produced a consistent and progressive cytopathic effect (CPE) in cell cultures. In this study, EP-1 cell cultures infected with EEHV (European eel herpesvirus) were examined using an electron microscope. Numerous nucleocapsids of about 100 nm in diameter were found within the nucleus of infected cells, whereas enveloped particles were observed within the cytoplasm. The mature viral particle, about 235 nm in diameter, had an electron-dense core with a hexagonal nucleocapsid surrounded by a coarse capsule. Histopathological examination of moribund fish showed epithelial hyperplasia with intracytoplasmic metabolic inclusions in the skin. Macrophage aggregates were found in liver, spleen, and kidney. A pair of primers designed from channel catfish virus and salmonid herpesvirus 1 was used in a polymerase chain reaction. A 402 bp fragment was amplified and cloned from genomic DNA of EEHV. The nucleotide homology was 99% (298 of 300) with DNA polymerase of eel herpesvirus (anguillid herpesvirus). EEHV nucleic acids were detected within melanomacrophages in the skin, liver, spleen and kidney by in situ hybridization (ISH). PMID:12180701

  10. Metabolic effects of kraft mill effluents on the eel Anguilla anguilla L

    SciTech Connect

    Santos, M.A.; Pires, F.; Hall, A. )

    1990-08-01

    Yellow eels (Anguilla anguilla L.) with an average weight of 60 g were used in this experiment. The fish were caught in June/July at the Aveiro Lagoon on the Portuguese West Coast, transported to the Department of Biology, Aveiro University, and kept in aerated aquaria for 1 week before the experiment started. The eels were then exposed for 1 and 3 weeks to 75 and 50% of the kraft pulp mill effluent. The eels exposed to the kraft pulp mill effluent developed an increase in red blood cell number per cubic millimeter and several biochemical changes, such as an increase in plasma lactate and sodium and a decrease in plasma pyruvate and potassium. Histological examination of the experimental eels exposed to the 50% kraft pulp mill effluent revealed deep alteration of the tissue structure, such as disruption of the skin and edematous hypertrophy of covering epithelial cells in secondary gill lamellae. The kidney had damage of the renal tubules. The liver developed necrosis supported by a significant decrease in GOT and GPT activity. The spleen had an increase in blood content as well as in pigment centers. Previous results indicated the kraft pulp mill effluent causes tissue damage and consequent metabolic changes in the eel Anguilla anguilla L.

  11. Enhancement and management of eel fisheries affected by hydroelectric dams in New Zealand

    USGS Publications Warehouse

    Boubee, J.; Chisnall, B.; Watene, E.; Williams, E.; Roper, D.; Haro, A.

    2003-01-01

    Two freshwater anguillid eel species, Anguilla australis and A. dieffenbachia, form the basis of important traditional, recreational, and commercial fisheries in New Zealand. These fisheries have been affected by the damming of many of the major waterways for hydroelectric generation. To create fisheries in reservoirs that would be otherwise inaccessible, elvers have been transferred from the base of dams into habitats upstream. Operations in three catchments: the Patea River (Lake Rotorangi), Waikato River (eight reservoirs notably the two lowermost, lakes Karapiro and Arapuni), and Rangitaiki River (lakes Matahina and Aniwhenua) are discussed. In all reservoirs, the transfers have successfully established fishable populations within six years of the first transfers and, in Lake Arapuni eels have reached the marketable size of 220 g in less than four years. In comparison, it typically takes from 13 to 17 years before eel populations are fishable in the lower Waikato River where direct access to the sea is available. Telemetry and monitoring at the screens and tailraces of several power stations have been used to determine migration timing, triggers, and pathways of mature eels. Successful downstream transfer of mature migrating adults has been achieved by spillway opening and netting in headraces during rain events in autumn, but means of preventing eels from impinging and entraining at the intakes are still required. An integrated, catchment-wide management system will be required to ensure sustainability of the fisheries. ?? Copyright by the American Fisheries Society 2003.

  12. What can we learn from monitoring PCBs in the European eel? A Belgian experience.

    PubMed

    Belpaire, Claude; Geeraerts, Caroline; Roosens, Laurence; Neels, Hugo; Covaci, Adrian

    2011-02-01

    Between 2000 and 2007 pooled muscle tissue samples of the European eel (Anguilla anguilla) from 48 sites in Flanders (Belgium) were analysed for 30 polychlorinated biphenyl (PCB) congeners. There was a large variation between individual sites (range 11-7752 ng/g wet weight (ww) for the sum of the ICES 7 PCBs), eels from the River Meuse basin (mean 1545 ng/g ww) being considerably more polluted than those from the River Scheldt (615) and IJzer (61) basins. Overall, PCB 153, PCB 138 and PCB 180 were the most prominent congeners, however PCB patterns varied between the monitored locations. Analysis of the weight percentage of congeners demonstrates obvious differences in PCB composition between sites, indicating differential sources of pollution. Due to the variation in patterns, atmospheric fallout does not seem to be the main source of the PCB spread, but instead both local and upstream sources linked to industrial activities seem to be the main cause for PCB presence in Flanders. Considering the levels of the Sum 7 PCBs, eels are not compliant with the Belgian legal limits for consumption (75 ng/g ww) in 71% of the sites. Regular consumption of eels from polluted sites leads to a considerable excess of the WHO Acceptable Daily Intake value. Consumption of wild eels should by all means be prevented, as it presents risks for human health, especially for local anglers consuming their catch. PMID:21075450

  13. Rhabdomyosarcoma in a Silver Carp.

    PubMed

    Rezaie, Annahita; Mousavi, Seyed Mohammad; Ansari, Mahshid Bagherzadeh

    2016-06-01

    Rhabdomyosarcoma is a primitive neoplasm that originates from skeletal muscle progenitor cells. In a routine inspection of a cyprinid farm in southwestern Iran, an approximately 2-year-old female Silver Carp was observed to have a raised mass located on the dorsolateral surface just caudal to the head. Macroscopic examination revealed a firm irregular fleshy pink mass (5 × 4 cm, depth = 3 cm) that appeared to arise from the subcutaneous musculature. Histologic sections were prepared using routine methods and separate sections were stained with hematoxylin-eosin and Massons' trichrome. Microscopically, the tumor mass was composed of spindle cells that were densely packed and arranged in long interwoven bundles. The nuclei were vesicular and oval to elongated or cigar-shaped. Nuclear pleomorphism and multinucleate tumor giant cells were clearly evident. The neoplastic cell cytoplasm was eosinophilic with indistinct cell margins, and clear cross striations were observed in fibrils. The striated fibrils stained diffusely red with Masson's trichrome. This account represents the first reported occurrence of rhabdomyosarcoma in Silver Carp Hypophthalmichthys molitrix. Received July 10, 2015; accepted February 4, 2016. PMID:27229885

  14. Transcript levels of the soluble sperm factor protein phospholipase C zeta 1 (PLCζ1) increase through induced spermatogenesis in European eel.

    PubMed

    Morini, Marina; Peñaranda, David S; Vílchez, María C; Gallego, Víctor; Nourizadeh-Lillabadi, Rasoul; Asturiano, Juan F; Weltzien, Finn-Arne; Pérez, Luz

    2015-09-01

    Activation at fertilization of the vertebrate egg is triggered by Ca(2+) waves. Recent studies suggest the phospholipase C zeta (PLCζ), a sperm-specific protein, triggers egg activation by an IP3-mediated Ca(2+) release and allow Ca(2+) waves at fertilization. In the present study we cloned, characterized, and phylogenetically positioned the European eel PLCζ (PLCζ1). It is 1521 bp long, with 10 exons encoding an open reading frame of 506 amino acids. The amino acid sequence contains an EF-hand domain, X and Y catalytic domains, and a carboxy-terminal C2 domain, all typical of other PLCζ orthologous. The tissue distribution was studied, and the gene expression was determined in testis during induced sexual maturation at three different thermal regimes. Also, brain and pituitary expression was studied through sex maturation at constant temperature. plcζ1 was expressed in brain of male and female, in testis but not in ovaries. By first time in vertebrates, it is reported plcζ1 expression in the pituitary gland. Testis plcζ1 expression increased through spermatogenesis under all the thermal regimes, but being significantly elevated at lower temperatures. It was very low when testis contained only spermatogonia or spermatocytes, while maximum expression was found during spermiogenesis. These results support the hypothesis for an eel sperm-specific PLCζ1 inducing egg activation, similarly to mammals and some teleosts, but different from some other teleost species, which express this protein in ovaries, but not in testes. PMID:26051612

  15. Helminths from the giant mottled eel Anguilla marmorata Quoy & Gaimard in Japan, with a description of Acanthocephalus longiacanthus n. sp. (Acanthocephala: Echinorhynchidae).

    PubMed

    Katahira, Hirotaka; Nagasawa, Kazuya

    2014-05-01

    Five helminths, including a new echinorhynchid acanthocephalan Acanthocephalus longiacanthus n. sp., are described based on specimens from the giant mottled eel Anguilla marmorata Quoy & Gaimard caught in a small river, western Japan. The new acanthocephalan is distinguished from the other congeners in terms of hook arrangement (8-9 longitudinal rows with 5-6 hooks per row) on proboscis, maximum length of hook blade (81-95 μm in male, 150-190 μm in female), lemnisci being longer than proboscis receptacle, and small-sized eggs (80-83 μm). Two monogeneans, Pseudodactylogyrus anguillae (Yin & Sproston, 1948) and P. bini (Kikuchi, 1929), and two acanthocephalans, Acanthocephalus gotoi Van Cleave, 1925 and Southwellina hispida (Van Cleave, 1925), were also found; this new material is described. The monogeneans are notorious as invasive parasites spreading worldwide via anthropogenic transportations of anguillid eels, but in Japanese waters A. marmorata appears to be an indigenous host for these parasites. Anguilla marmorata is a new host record for the acanthocephalans A. gotoi and S. hispida. PMID:24711116

  16. Data on the characterization of follicle-stimulating hormone monoclonal antibodies and localization in Japanese eel pituitary.

    PubMed

    Kim, Dae-Jung; Park, Chae-Won; Byambaragchaa, Munkhzaya; Kim, Shin-Kwon; Lee, Bae-Ik; Hwang, Hyung-Kyu; Myeong, Jeong-In; Hong, Sun-Mee; Kang, Myung-Hwa; Min, Kwan-Sik

    2016-09-01

    Monoclonal antibodies were generated against recombinant follicle-stimulating hormone (rec-FSH) from Japanese eel Anguilla japonica; rec-FSH was produced in Escherichia coli and purified using Ni-NTA Sepharose column chromatography. In support of our recent publication, "Production and characterization of monoclonal antibodies against recombinant tethered follicle-stimulating hormone from Japanese eel Anguilla japonica" [1], it was important to characterize the specificity of eel follicle-stimulating hormone antibodies. Here, the production and ELISA system of these monoclonal antibodies are presented. The affinity-purified monoclonal antibodies specifically detected eel rec-FSH in ELISA and on western blots of rec-FSH produced from CHO cells. Immunohistochemical analysis revealed that FSH staining was specifically localized in the eel pituitary. PMID:27331121

  17. Direct observations of American eels migrating across the continental shelf to the Sargasso Sea.

    PubMed

    Béguer-Pon, Mélanie; Castonguay, Martin; Shan, Shiliang; Benchetrit, José; Dodson, Julian J

    2015-01-01

    Since inferring spawning areas from larval distributions in the Sargasso Sea a century ago, the oceanic migration of adult American eels has remained a mystery. No adult eel has ever been observed migrating in the open ocean or in the spawning area. Here, we track movements of maturing eels equipped with pop-up satellite archival tags from the Scotian Shelf (Canada) into the open ocean, with one individual migrating 2,400 km to the northern limit of the spawning site in the Sargasso Sea. The reconstructed routes suggest a migration in two phases: one over the continental shelf and along its edge in shallow waters; the second in deeper waters straight south towards the spawning area. This study is the first direct evidence of adult Anguilla migrating to the Sargasso Sea and represents an important step forward in the understanding of routes and migratory cues. PMID:26505325

  18. Dramatic effect of pop-up satellite tags on eel swimming.

    PubMed

    Burgerhout, Erik; Manabe, Ryotaro; Brittijn, Sebastiaan A; Aoyama, Jun; Tsukamoto, Katsumi; van den Thillart, Guido E E J M

    2011-07-01

    The journey of the European eel to the spawning area in the Sargasso Sea is still a mystery. Several trials have been carried out to follow migrating eels with pop-up satellite tags (PSATs), without much success. As eels are very efficient swimmers, tags likely interfere with their high swimming efficiency. Here we report a more than twofold increase in swimming cost caused by a regular small satellite tag. The impact was determined at a range of swimming speeds with and without tag in a 2-m swimming tunnel. These results help to explain why the previous use of PSATs to identify spawning sites in the Sargasso Sea was thus far unsuccessful. PMID:21594613

  19. Direct observations of American eels migrating across the continental shelf to the Sargasso Sea

    PubMed Central

    Béguer-Pon, Mélanie; Castonguay, Martin; Shan, Shiliang; Benchetrit, José; Dodson, Julian J.

    2015-01-01

    Since inferring spawning areas from larval distributions in the Sargasso Sea a century ago, the oceanic migration of adult American eels has remained a mystery. No adult eel has ever been observed migrating in the open ocean or in the spawning area. Here, we track movements of maturing eels equipped with pop-up satellite archival tags from the Scotian Shelf (Canada) into the open ocean, with one individual migrating 2,400 km to the northern limit of the spawning site in the Sargasso Sea. The reconstructed routes suggest a migration in two phases: one over the continental shelf and along its edge in shallow waters; the second in deeper waters straight south towards the spawning area. This study is the first direct evidence of adult Anguilla migrating to the Sargasso Sea and represents an important step forward in the understanding of routes and migratory cues. PMID:26505325

  20. Regional variation in energy storage strategies in American glass eels from Eastern Canada.

    PubMed

    Gaillard, Mélanie; Bernatchez, Louis; Tremblay, Réjean; Audet, Céline

    2015-10-01

    Energy status was analyzed in glass eels captured during two early waves of arrival at the mouths of the Mersey River, Nova Scotia, Canada (MR), and Grande-Rivière-Blanche, Québec, Canada (GRB), and according to their salinity preference (freshwater, brackish, or saltwater). Glass eels captured in the GRB estuary were larger, more pigmented, and exhibited higher whole-body glycogen, phospholipid, and sterol and wax ester contents. Those from MR had a higher condition index and a higher whole-body triacylglycerol content, suggesting different patterns of storage and/or use of energy reserves. Within a river, a delay of two weeks in estuarine arrival was characterized by significantly lower energy reserves. No differences in energy storage were observed according to salinity preference. Thus, the results revealed the occurrence of different energy storage strategies according to glass eel migration distance and duration, but not according to salinity preference. PMID:26119597

  1. [Effect of different ecological factors on ricefield eel (Monopterus albus) hatching rate].

    PubMed

    Yin, Shaowu; Zhou, Gongjian; Liu, Yun

    2004-04-01

    This paper studied the effects, of some ecological factors (temperature, pH, hatching method and ammonia) on the embryonic development of ricefield eel. The results indicated that the optimum hatching temperature of ricefield eel was 25-28 degrees C, and no significant difference was found about the effects of pH within the range of pH 5.5-9.5 on the hatching rate of oosperm. Dripping water incubation had a higher hatching rate of oosperm than staticing water incubation, and the hatching rate of oosperm decreased with increasing ammonia content. The present study provided an available suggestion for the all-artificial and half-artificial breeding of ricefield eel. PMID:15334981

  2. PCB and organochlorine pesticide burden in eels in the lower Thames River (UK).

    PubMed

    Jürgens, Monika D; Chaemfa, Chakra; Hughes, David; Johnson, Andrew C; Jones, Kevin C

    2015-01-01

    Thirty-five European eels (Anguilla anguilla), caught in 2007 in the river Thames upstream and downstream of both London and the tidal limit, were analysed for PCBs and organochlorine pesticides. Most chemicals were detectable in every fish, although they have been banned or severely restricted for many years. In general, the tidal eels were more contaminated than upstream ones, which was related to their higher lipid contents. The ICES7 indicator PCB concentrations ranged overall from 4.2 to 124μgkg(-1) fresh weight with averages of 33 and 56μgkg(-1) for the upstream and tidal eels; 3.5-104μgkg(-1), average 26 and 48μgkg(-1) of that were ICES6 PCBs. Total DDT was on average 16μgkg(-1) (1.7-38μgkg(-1)) upstream and 18μgkg(-1) (8.6-35μgkg(-1)) downstream with about half of that provided by pp'DDE. Lindane (γ-HCH) was found at up to 2.8μgkg(-1) (averages 0.58 and 1.1μgkg(-1) upstream and downstream) and hexachlorobenzene (HCB) was on average 1.9 and 2.5μgkg(-1) in the two groups with a maximum of 6.4μgkg(-1) in each. Therefore all individuals passed the European Environmental Quality Standard (EQS) of 10μgkg(-1) for HCB. PCB contamination was fairly typical for recent UK eel data, whilst DDE and lindane concentrations were lower than most previous UK eel studies, perhaps reflecting a downward trend. Although not as highly contaminated as some eels from previous UK and European studies, the presence of so many of these chemicals, with their known health effects may represent a stress for the fish or higher predators, such as birds. PMID:25078785

  3. Spawning Sites of the Japanese Eel in Relation to Oceanographic Structure and the West Mariana Ridge

    PubMed Central

    Aoyama, Jun; Watanabe, Shun; Miller, Michael J.; Mochioka, Noritaka; Otake, Tsuguo; Yoshinaga, Tatsuki; Tsukamoto, Katsumi

    2014-01-01

    The Japanese eel, Anguilla japonica, spawns within the North Equatorial Current that bifurcates into both northward and southward flows in its westward region, so its spawning location and larval transport dynamics seem important for understanding fluctuations in its recruitment to East Asia. Intensive research efforts determined that Japanese eels spawn along the western side of the West Mariana Ridge during new moon periods, where all oceanic life history stages have been collected, including eggs and spawning adults. However, how the eels decide where to form spawning aggregations is unknown because spawning appears to have occurred at various latitudes. A salinity front formed from tropical rainfall was hypothesized to determine the latitude of its spawning locations, but an exact spawning site was only found once by collecting eggs in May 2009. This study reports on the collections of Japanese eel eggs and preleptocephali during three new moon periods in June 2011 and May and June 2012 at locations indicating that the distribution of lower salinity surface water or salinity fronts influence the latitude of spawning sites along the ridge. A distinct salinity front may concentrate spawning south of the front on the western side of the seamount ridge. It was also suggested that eels may spawn at various latitudes within low-salinity water when the salinity fronts appeared unclear. Eel eggs were distributed within the 150–180 m layer near the top of the thermocline, indicating shallow spawning depths. Using these landmarks for latitude (salinity front), longitude (seamount ridge), and depth (top of the thermocline) to guide the formation of spawning aggregations could facilitate finding mates and help synchronize their spawning. PMID:24551155

  4. Impacts of Interannual Ocean Circulation Variability on Japanese Eel Larval Migration in the Western North Pacific Ocean.

    PubMed

    Chang, Yu-Lin; Sheng, Jinyu; Ohashi, Kyoko; Béguer-Pon, Mélanie; Miyazawa, Yasumasa

    2015-01-01

    The Japanese eel larvae hatch near the West Mariana Ridge seamount chain and travel through the North Equatorial Current (NEC), the Kuroshio, and the Subtropical Countercurrent (STCC) region during their shoreward migration toward East Asia. The interannual variability of circulation over the subtropical and tropical regions of the western North Pacific Ocean is affected by the Philippines-Taiwan Oscillation (PTO). This study examines the effect of the PTO on the Japanese eel larval migration routes using a three-dimensional (3D) particle tracking method, including vertical and horizontal swimming behavior. The 3D circulation and hydrography used for particle tracking are from the ocean circulation reanalysis produced by the Japan Coastal Ocean Predictability Experiment 2 (JCOPE2). Our results demonstrate that bifurcation of the NEC and the strength and spatial variation of the Kuroshio affect the distribution and migration of eel larvae. During the positive phase of PTO, more virtual eels ("v-eels") can enter the Kuroshio to reach the south coast of Japan and more v-eels reach the South China Sea through the Luzon Strait; the stronger and more offshore swing of the Kuroshio in the East China Sea leads to fewer eels entering the East China Sea and the onshore movement of the Kuroshio to the south of Japan brings the eels closer to the Japanese coast. Significant differences in eel migration routes and distributions regulated by ocean circulation in different PTO phases can also affect the otolith increment. The estimated otolith increment suggests that eel age tends to be underestimated after six months of simulation due to the cooler lower layer temperature. Underestimation is more significant in the positive PTO years due to the wide distribution in higher latitudes than in the negative PTO years. PMID:26642318

  5. Silver recovery system data

    SciTech Connect

    Boulineau, B.

    1991-08-26

    In August of 1990 the Savannah River Site Photography Group began testing on a different type of silver recovery system. This paper describes the baseline study and the different phases of installation and testing of the system.

  6. Female circumcision.

    PubMed

    Abu Daia, J M

    2000-10-01

    It is uncertain when female circumcision was first practiced, but it certainly preceded the founding of both Christianity and Islam. A review of past and current historical, popular and professional literature was undertaken, and 4 types of female circumcision were identified. Typically female circumcision is performed by a local village practitioner, lay person or by untrained midwives. Female genital mutilation is not accepted by any religious or medical opinion, and is a violation of human rights against helpless individuals who are unable to provide informed consent and who must therefore be protected through education and legislation. Complications of female circumcision can present after many years. Any medical practitioner (either for adult or pediatric) can be confronted with this issue of female circumcision, even in countries where this custom is not present, thus mandating the understanding of this complex issue. PMID:11369952

  7. Abuse of silver-nitrate solution for planing periorbital folds.

    PubMed

    Schepler, Hadrian; Kessler, Jens; Hartmann, Bernd

    2002-02-01

    When using a Hollensteinstift to treat periorbital folds a 28-year-old female patient perceived a chemical burn of the lower lids and the periorbital regions. The initial treatment was frequent washing with soap solution and topical panthenol ointment. This unusual case is demonstrated to show the risks of improper use of silver-nitrate solution and to discuss therapeutic options. PMID:11834338

  8. Qualitative assessment of the diet of European eel larvae in the Sargasso Sea resolved by DNA barcoding.

    PubMed

    Riemann, Lasse; Alfredsson, Hanna; Hansen, Michael M; Als, Thomas D; Nielsen, Torkel G; Munk, Peter; Aarestrup, Kim; Maes, Gregory E; Sparholt, Henrik; Petersen, Michael I; Bachler, Mirjam; Castonguay, Martin

    2010-12-23

    European eels (Anguilla anguilla) undertake spawning migrations of more than 5000 km from continental Europe and North Africa to frontal zones in the Sargasso Sea. Subsequently, the larval offspring are advected by large-scale eastward ocean currents towards continental waters. However, the Sargasso Sea is oligotrophic, with generally low plankton biomass, and the feeding biology of eel larvae has so far remained a mystery, hampering understanding of this peculiar life history. DNA barcoding of gut contents of 61 genetically identified A. anguilla larvae caught in the Sargasso Sea showed that even the smallest larvae feed on a striking variety of plankton organisms, and that gelatinous zooplankton is of fundamental dietary importance. Hence, the specific plankton composition seems essential for eel larval feeding and growth, suggesting a linkage between eel survival and regional plankton productivity. These novel insights into the prey of Atlantic eels may furthermore facilitate eel larval rearing in aquaculture, which ultimately may replace the unsustainable use of wild-caught glass eels. PMID:20573615

  9. Gnathostoma spinigerum in live Asian swamp eels (Monopterus spp.) from food markets and wild populations, United States

    USGS Publications Warehouse

    Cole, Rebecca A.; Choudhury, Anindo; Nico, Leo G.; Griffin, Kathryn M.

    2014-01-01

    In Southeast Asia, swamp eels (Synbranchidae: Monopterus spp.) are a common source of human gnathostomiasis, a foodborne zoonosis caused by advanced third-stage larvae (AL3) of Gnathostoma spp. nematodes. Live Asian swamp eels are imported to US ethnic food markets, and wild populations exist in several states. To determine whether these eels are infected, we examined 47 eels from markets and 67 wild-caught specimens. Nematodes were identified by morphologic features and ribosomal intergenic transcribed spacer–2 gene sequencing. Thirteen (27.7%) M. cuchia eels from markets were infected with 36 live G. spinigerum AL3: 21 (58.3%) in liver; 7 (19.4%) in muscle; 5 (13.8%) in gastrointestinal tract, and 3 (8.3%) in kidneys. Three (4.5%) wild-caught M. albus eels were infected with 5 G. turgidum AL3 in muscle, and 1 G. lamothei AL3 was found in a kidney (both North American spp.). Imported live eels are a potential source of human gnathostomiasis in the United States.

  10. Gnathostoma spinigerum in Live Asian Swamp Eels (Monopterus spp.) from Food Markets and Wild Populations, United States

    PubMed Central

    Choudhury, Anindo; Nico, Leo G.; Griffin, Kathryn M.

    2014-01-01

    In Southeast Asia, swamp eels (Synbranchidae: Monopterus spp.) are a common source of human gnathostomiasis, a foodborne zoonosis caused by advanced third-stage larvae (AL3) of Gnathostoma spp. nematodes. Live Asian swamp eels are imported to US ethnic food markets, and wild populations exist in several states. To determine whether these eels are infected, we examined 47 eels from markets and 67 wild-caught specimens. Nematodes were identified by morphologic features and ribosomal intergenic transcribed spacer–2 gene sequencing. Thirteen (27.7%) M. cuchia eels from markets were infected with 36 live G. spinigerum AL3: 21 (58.3%) in liver; 7 (19.4%) in muscle; 5 (13.8%) in gastrointestinal tract, and 3 (8.3%) in kidneys. Three (4.5%) wild-caught M. albus eels were infected with 5 G. turgidum AL3 in muscle, and 1 G. lamothei AL3 was found in a kidney (both North American spp.). Imported live eels are a potential source of human gnathostomiasis in the United States. PMID:24661441

  11. Leaching of Silver from Silver-Impregnated Food Storage Containers

    ERIC Educational Resources Information Center

    Hauri, James F.; Niece, Brian K.

    2011-01-01

    The use of silver in commercial products has proliferated in recent years owing to its antibacterial properties. Food containers impregnated with micro-sized silver promise long food life, but there is some concern because silver can leach out of the plastic and into the stored food. This laboratory experiment gives students the opportunity to…

  12. Response of seaward-migrating European eel (Anguilla anguilla) to manipulated flow fields.

    PubMed

    Piper, Adam T; Manes, Costantino; Siniscalchi, Fabio; Marion, Andrea; Wright, Rosalind M; Kemp, Paul S

    2015-07-22

    Anthropogenic structures (e.g. weirs and dams) fragment river networks and restrict the movement of migratory fish. Poor understanding of behavioural response to hydrodynamic cues at structures currently limits the development of effective barrier mitigation measures. This study aimed to assess the effect of flow constriction and associated flow patterns on eel behaviour during downstream migration. In a field experiment, we tracked the movements of 40 tagged adult European eels (Anguilla anguilla) through the forebay of a redundant hydropower intake under two manipulated hydrodynamic treatments. Interrogation of fish trajectories in relation to measured and modeled water velocities provided new insights into behaviour, fundamental for developing passage technologies for this endangered species. Eels rarely followed direct routes through the site. Initially, fish aligned with streamlines near the channel banks and approached the intake semi-passively. A switch to more energetically costly avoidance behaviours occurred on encountering constricted flow, prior to physical contact with structures. Under high water velocity gradients, fish then tended to escape rapidly back upstream, whereas exploratory 'search' behaviour was common when acceleration was low. This study highlights the importance of hydrodynamics in informing eel behaviour. This offers potential to develop behavioural guidance, improve fish passage solutions and enhance traditional physical screening. PMID:26136454

  13. Response of seaward-migrating European eel (Anguilla anguilla) to manipulated flow fields

    PubMed Central

    Piper, Adam T.; Manes, Costantino; Siniscalchi, Fabio; Marion, Andrea; Wright, Rosalind M.; Kemp, Paul S.

    2015-01-01

    Anthropogenic structures (e.g. weirs and dams) fragment river networks and restrict the movement of migratory fish. Poor understanding of behavioural response to hydrodynamic cues at structures currently limits the development of effective barrier mitigation measures. This study aimed to assess the effect of flow constriction and associated flow patterns on eel behaviour during downstream migration. In a field experiment, we tracked the movements of 40 tagged adult European eels (Anguilla anguilla) through the forebay of a redundant hydropower intake under two manipulated hydrodynamic treatments. Interrogation of fish trajectories in relation to measured and modelled water velocities provided new insights into behaviour, fundamental for developing passage technologies for this endangered species. Eels rarely followed direct routes through the site. Initially, fish aligned with streamlines near the channel banks and approached the intake semi-passively. A switch to more energetically costly avoidance behaviours occurred on encountering constricted flow, prior to physical contact with structures. Under high water velocity gradients, fish then tended to escape rapidly back upstream, whereas exploratory ‘search’ behaviour was common when acceleration was low. This study highlights the importance of hydrodynamics in informing eel behaviour. This offers potential to develop behavioural guidance, improve fish passage solutions and enhance traditional physical screening. PMID:26136454

  14. Effects of salinity change on two superoxide dismutases (SODs) in juvenile marbled eel Anguilla marmorata

    PubMed Central

    2016-01-01

    Salinity is one of the most important factors that affect the fish growth and survival. Superoxide dismutases (SODs), as the primary antioxidant enzymes, play a first role in the process of preventing oxidative stress caused by excessive superoxide anion (O\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}${}_{2}^{-}$\\end{document}2−) in living organisms. In the present study, we investigated the effects of salinity on the gene expressions as well as enzymatic activities of MnSOD and Cu/ZnSOD in gill, intestine, kidney, liver and muscle tissues of the marbled eel Anguilla marmorata. We found that the liver might possess stronger redox capacity compared with other tissues. Furthermore, the gene expressions and enzymatic activities of SODs in juvenile marbled eels could be effectively enhanced by low salinity but inhibited when the salinity was higher than the body tolerance. Our findings indicated that MnSOD and Cu/ZnSOD played vital roles in the adaptation of marbled eels to salinity variation, which contributed to the elucidation of physiological adaptation and regulatory mechanism of SODs in eels. PMID:27547518

  15. To boldly climb: behavioural and cognitive differences in migrating European glass eels

    PubMed Central

    Podgorniak, T.; Blanchet, S.; De Oliveira, E.; Daverat, F.; Pierron, F.

    2016-01-01

    European eel (Anguilla anguilla) is a catadromous fish species that received substantial attention as its population has markedly declined in the last three decades. The possible causes of this decline include habitat fragmentation factors such as dams and weirs. In some cases, these obstacles are equipped with fish friendly passage devices that may select young eels according to their climbing behaviour. We tested how individual climbing tendency was related to the event of fishway passage experienced in the field and classified fish climbing profiles as climbing ‘leaders’, ‘followers’, ‘finishers’ and ‘no climbers’. Moreover, we analysed the brain transcription level of genes related to neurogenesis and synaptic plasticity and compared it to climbing profiles. We found that fish from the upstream segments of an impounded river had a higher climbing propensity. Their behaviour was also more repeatable throughout the whole test than the obstacle-naive fish from the downstream segment. Moreover, we found that boldly climbing ‘leaders’ had lower levels of transcription of synapse-related genes than the climbing ‘followers’. These differences could be related to coping styles of fish, where proactive ‘leaders’ express a routine and risky behaviour, whereas reactive fish need an environmental assessment before exploratory behaviour. Our study showed that differences in climbing propensity exist in glass eels separated by water obstacles. Moreover, eels could adopt climbing different strategies according to the way they deal with environmental stress and to the cognitive abilities they possess. PMID:26909192

  16. To boldly climb: behavioural and cognitive differences in migrating European glass eels.

    PubMed

    Podgorniak, T; Blanchet, S; De Oliveira, E; Daverat, F; Pierron, F

    2016-01-01

    European eel (Anguilla anguilla) is a catadromous fish species that received substantial attention as its population has markedly declined in the last three decades. The possible causes of this decline include habitat fragmentation factors such as dams and weirs. In some cases, these obstacles are equipped with fish friendly passage devices that may select young eels according to their climbing behaviour. We tested how individual climbing tendency was related to the event of fishway passage experienced in the field and classified fish climbing profiles as climbing 'leaders', 'followers', 'finishers' and 'no climbers'. Moreover, we analysed the brain transcription level of genes related to neurogenesis and synaptic plasticity and compared it to climbing profiles. We found that fish from the upstream segments of an impounded river had a higher climbing propensity. Their behaviour was also more repeatable throughout the whole test than the obstacle-naive fish from the downstream segment. Moreover, we found that boldly climbing 'leaders' had lower levels of transcription of synapse-related genes than the climbing 'followers'. These differences could be related to coping styles of fish, where proactive 'leaders' express a routine and risky behaviour, whereas reactive fish need an environmental assessment before exploratory behaviour. Our study showed that differences in climbing propensity exist in glass eels separated by water obstacles. Moreover, eels could adopt climbing different strategies according to the way they deal with environmental stress and to the cognitive abilities they possess. PMID:26909192

  17. Climbing experience in glass eels: A cognitive task or a matter of physical capacities?

    PubMed

    Podgorniak, T; Angelini, A; Blanchet, S; de Oliveira, E; Pierron, F; Daverat, F

    2015-11-01

    The European eel is a panmictic species, whose decline has been recorded since the last 30 years. Among human-induced environmental factors of decline, the impact of water dams during species migration is questioned. Indeed, water impoundments can be a severe obstacle for young eels trying to reach the upstream freshwater zones, even if they are equipped with fish-friendly passes. The passage by such devices could be an important event shaping the outcome of the future life and life history traits of eels. We studied what phenotypic traits were associated with the event of experience of passage by water obstacles. We analyzed specific enzyme activities and/or gene transcription levels in the muscle and brain to test whether the obstacle passage is rather a physical or cognitive task. We found that after a long period of maintenance under homogenous conditions, transcription levels of several genes linked to synaptic plasticity, neurogenesis and thyroid activity differed among the field-experience groups. In contrast, muscle gene transcription levels or enzymatic activities did not show any differences among fish groups. We suggest that cognitive processes such as learning and memory acquisition rather than swimming-related metabolic capacities are involved in passage of water obstacles by young eels. PMID:26260433

  18. Sub-decadal turbidite frequency during the early Holocene: Eel Fan, offshore northern California

    USGS Publications Warehouse

    Paull, Charles K.; McGann, Mary L.; Sumner, Esther J; Barnes, Philip M; Lundsten, Eve M; Anderson, Krystle; Gwiazda, Roberto; Edwards, Brian D.; Caress, David W

    2014-01-01

    Remotely operated and autonomous underwater vehicle technologies were used to image and sample exceptional deep sea outcrops where an ∼100-m-thick section of turbidite beds is exposed on the headwalls of two giant submarine scours on Eel submarine fan, offshore northern California (USA). These outcrops provide a rare opportunity to connect young deep-sea turbidites with their feeder system. 14C measurements reveal that from 12.8 ka to 7.9 ka, one turbidite was being emplaced on average every 7 yr. This emplacement rate is two to three orders of magnitude higher than observed for turbidites elsewhere along the Pacific margin of North America. The turbidites contain abundant wood and shallow-dwelling foraminifera, demonstrating an efficient connection between the Eel River source and the Eel Fan sink. Turbidite recurrence intervals diminish fivefold to ∼36 yr from 7.9 ka onward, reflecting sea-level rise and re-routing of Eel River sediments.

  19. Replicating phages in the epidermal mucosa of the eel (Anguilla anguilla)

    PubMed Central

    Carda-Diéguez, Miguel; Mizuno, Carolina Megumi; Ghai, Rohit; Rodriguez-Valera, Francisco; Amaro, Carmen

    2015-01-01

    In this work, we used the eel (Anguilla anguilla) as an animal model to test the hypothesis of Barr et al. (2013a,b) about the putative role of the epidermal mucosa as a phage enrichment layer. To this end, we analyzed the microbial content of the skin mucus of wild and farmed eels by using a metagenomic approach. We found a great abundance of replicating phage genomes (concatemers) in all the samples. They were assembled in four complete genomes of three Myovirus and one Podovirus. We also found evidences that ΦKZ and Podovirus phages could be part of the resident microbiota associated to the eel mucosal surface and persist on them over the time. Moreover, the viral abundance estimated by epiflorescent counts and by metagenomic recruitment from eel mucosa was higher than that of the surrounding water. Taken together, our results support the hypothesis that claims a possible role of phages in the animal mucus as agents controlling bacterial populations, including pathogenic species, providing a kind of innate immunity. PMID:25688234

  20. Teaching Population Growth Using Cultures of Vinegar Eels, "Turbatrix aceti" (Nematoda)

    ERIC Educational Resources Information Center

    Wallace, Robert L.

    2005-01-01

    A simple laboratory exercise is presented that follows the population growth of the common vinegar eel, "Turbatrix aceti" (Nematoda), in a microcosm using a simple culture medium. It lends itself to an exercise in a single semester course. (Contains 4 figures.)

  1. A survey of infective larvae of Gnathostoma in eels sold in Ho Chi Minh City.

    PubMed

    Le, T X; Rojekittikhun, W

    2000-03-01

    To investigate the distribution of Gnathostoma spp in Ho Chi Minh City (HCM city), 1,081 eels were purchased from a local market twice a month from March 1998 to February 1999. Infective larvae of Gnathostoma spp detected from the flesh and liver of eels by the press preparation technique were examined and identified. Three hundred and fifty advanced third-stage larvae were recovered from liver, none from the flesh. The average rate of infection was 0.11; a high rate of infection was found from August to November and a low rate of infection from February to May. The average number of larvae/eel was 2.9; the greatest number of larvae/eel was in January whereas the lowest was in March and April. There was a marked decrease in both prevalence and intensity of infection from February to May, followed by a rise from June. The finding suggests that in HCM city, the infection rate abruptly decreases soon after the end of the rainy season and starts to rise when the rain comes and reaches its peak at the end of the rainy season. All recovered larvae were identified as G. spinigerum. PMID:11023080

  2. Effects of salinity change on two superoxide dismutases (SODs) in juvenile marbled eel Anguilla marmorata.

    PubMed

    Wang, Li; Wang, Xiaolu; Yin, Shaowu

    2016-01-01

    Salinity is one of the most important factors that affect the fish growth and survival. Superoxide dismutases (SODs), as the primary antioxidant enzymes, play a first role in the process of preventing oxidative stress caused by excessive superoxide anion (O[Formula: see text]) in living organisms. In the present study, we investigated the effects of salinity on the gene expressions as well as enzymatic activities of MnSOD and Cu/ZnSOD in gill, intestine, kidney, liver and muscle tissues of the marbled eel Anguilla marmorata. We found that the liver might possess stronger redox capacity compared with other tissues. Furthermore, the gene expressions and enzymatic activities of SODs in juvenile marbled eels could be effectively enhanced by low salinity but inhibited when the salinity was higher than the body tolerance. Our findings indicated that MnSOD and Cu/ZnSOD played vital roles in the adaptation of marbled eels to salinity variation, which contributed to the elucidation of physiological adaptation and regulatory mechanism of SODs in eels. PMID:27547518

  3. Hormonal induction of all stages of spermatogenesis in vitro in the male Japanese eel (Anguilla japonica).

    PubMed Central

    Miura, T; Yamauchi, K; Takahashi, H; Nagahama, Y

    1991-01-01

    The importance of gonadotropins and androgens for spermatogenesis is generally accepted in vertebrates, but the role played by specific hormones has not been clarified. Under cultivation conditions, male Japanese eels (Anguilla japonica) have immature testes containing only premitotic spermatogonia, type A and early-type B spermatogonia. In the present study, a recently developed organ-culture system for eel testes was used to determine in vitro effects of various steroid hormones on spermatogenesis. After 9 days of culture in serum-free, chemically defined medium containing 11-ketotestosterone (10 ng/ml), a major androgen in male eels, type A and early-type B spermatogonia began mitosis, producing late-type B spermatogonia. After 18 days, zygotene spermatocytes with synaptonemal complexes appeared, indicating that meiosis had already started by this time. In testis fragments cultured for 21 days, round spermatids and spermatozoa were observed with spermatogenic cells at all stages of development. Addition of 11-ketotestosterone to the culture medium also caused a marked cytological activation of Sertoli cells. No other steroid hormones tested had such stimulatory effects. These results, together with our earlier observations, suggest the following sequence for the hormonal induction of spermatogenesis in eel testes; gonadotropin stimulates the Leydig cells to produce 11-ketotestosterone, which, in turn, activates the Sertoli cells leading to the completion of spermatogenesis. This is, thus, an example of an animal system in which all stages of spermatogenesis have been induced by hormonal manipulation in vitro. Images PMID:2062857

  4. Compositions and functions of the hatching froth from ricefield eel (Monopterus albus Zuiew).

    PubMed

    Yin, Shaowu; Liu, Yun

    2010-06-01

    The ricefield eel (Monopterus albus) is an economic fish species in China. To improve its artificial reproduction, we studied the compositions and functions of the hatching froth secreted by ricefield eels. The froth showed a viscosity of 2.72 mPaS, composed of glycoproteins with a sugar content of 0.156 mg/ml and a protein content of 0.250 mg/ml at a ratio of 1.60. The froth proteins were identified by SDS-PAGE as four proteins with the molecular weights of 42.5, 58.6, 65.3, and 98.2 kDa respectively. Their total amino acid content was 201.88 mg/100 ml, consisting of 16 kinds of amino acids. Filed observation revealed three beneficial effects of the froth on the hatching of the eel eggs. First, the froth increased the hatching rates of fertilized eggs at a range of water temperatures. Second, the froth decreased the rates of infection of the fertilized eggs by the water mold. Finally, the froth accelerated velum breakage in the fertilized eggs. Of the different hatching methods, froth incubation achieved the highest hatching rate and larvae survival rate. These results demonstrate the indispensable function of the froth of ricefield eels, and offer practical reasons for protecting the froth during the breeding season. PMID:18949569

  5. Comparative imaging of European eels (Anguilla anguilla) for the evaluation of swimbladder nematode (Anguillicoloides crassus) infestation.

    PubMed

    Frisch, K; Davie, A; Schwarz, T; Turnbull, J F

    2016-06-01

    This study compares diagnostic imaging tools in detecting the parasitic swimbladder nematode Anguillicoloides crassus in Anguilla anguilla (L.) and focuses on ultrasound in an attempt to develop a non-destructive, field diagnostic test. Ultrasound use could allow the parasite to be diagnosed without decreasing the number of critically endangered European eels through post-mortem. In the preliminary study, eels were examined with computed radiography, computed tomography, magnetic resonance imaging, 14 MHz high-end ultrasound and 5 MHz low-end portable ultrasound, and the results were compared with post-mortem findings. This ultrasound scanning technique did not produce any promising results. A second batch of eels was examined using the same high-end and low-end ultrasounds, but employing a different scanning technique and comparing the results with post-mortem. This second study, scanning along the midline from below, allowed for the detection of anomalies associated with moderately infected animals. None of the eels used in this study were severely infected; thus, no conclusions can be made regarding the use of ultrasound in those animals. Overall, it was found that none of the techniques were useful in diagnosing mildly infected individuals; therefore, no single diagnostic imaging tool is sensitive enough to replace post-mortem for definite diagnosis. PMID:25952716

  6. Impacts of Interannual Ocean Circulation Variability on Japanese Eel Larval Migration in the Western North Pacific Ocean

    PubMed Central

    Chang, Yu-Lin; Sheng, Jinyu; Ohashi, Kyoko; Béguer-Pon, Mélanie; Miyazawa, Yasumasa

    2015-01-01

    The Japanese eel larvae hatch near the West Mariana Ridge seamount chain and travel through the North Equatorial Current (NEC), the Kuroshio, and the Subtropical Countercurrent (STCC) region during their shoreward migration toward East Asia. The interannual variability of circulation over the subtropical and tropical regions of the western North Pacific Ocean is affected by the Philippines–Taiwan Oscillation (PTO). This study examines the effect of the PTO on the Japanese eel larval migration routes using a three-dimensional (3D) particle tracking method, including vertical and horizontal swimming behavior. The 3D circulation and hydrography used for particle tracking are from the ocean circulation reanalysis produced by the Japan Coastal Ocean Predictability Experiment 2 (JCOPE2). Our results demonstrate that bifurcation of the NEC and the strength and spatial variation of the Kuroshio affect the distribution and migration of eel larvae. During the positive phase of PTO, more virtual eels (“v-eels”) can enter the Kuroshio to reach the south coast of Japan and more v-eels reach the South China Sea through the Luzon Strait; the stronger and more offshore swing of the Kuroshio in the East China Sea leads to fewer eels entering the East China Sea and the onshore movement of the Kuroshio to the south of Japan brings the eels closer to the Japanese coast. Significant differences in eel migration routes and distributions regulated by ocean circulation in different PTO phases can also affect the otolith increment. The estimated otolith increment suggests that eel age tends to be underestimated after six months of simulation due to the cooler lower layer temperature. Underestimation is more significant in the positive PTO years due to the wide distribution in higher latitudes than in the negative PTO years. PMID:26642318

  7. Salinity-dependent in vitro effects of homologous natriuretic peptides on the pituitary-interrenal axis in eels.

    PubMed

    Ventura, Albert; Kusakabe, Makoto; Takei, Yoshio

    2011-08-01

    We examined the effects of atrial, B-type, ventricular and C-type natriuretic peptides (ANP, BNP, VNP and CNP1, 3, 4) on cortisol secretion from interrenal tissue in vitro in both freshwater (FW) and seawater (SW)-acclimated eels. We first localized the interrenal and chromaffin cells in the eel head kidney using cell specific markers (cholesterol side-chain cleavage enzyme (P450ssc) and tyrosine hydroxylase (TH), respectively) and established the in vitro incubation system for eel interrenal tissue. Unexpectedly, none of the NPs given alone to the interrenal tissue of FW and SW eels stimulated cortisol secretion. However, ANP and VNP, but not BNP and three CNPs, enhanced the steroidogenic action of ACTH in SW interrenal preparations, while CNP1 and CNP4, but not ANP, BNP, VNP and CNP3, potentiated the ACTH action in FW preparations. These salinity dependent effects of NPs are consistent with the previous in vivo study in the eel where endogenous ACTH can act with the injected NPs. 8-Br-cGMP also enhanced the ACTH action in both FW and SW eel preparations, suggesting that the NP actions were mediated by the guanylyl cyclase-coupled NP receptors (GC-A and B) that were localized in the eel interrenal. Further, ANP and CNP1 stimulated ACTH secretion from isolated pituitary glands of SW and/or FW eels. In summary, the present study revealed complex mechanisms of NP action on corticosteroidogenesis through the pituitary-interrenal axis in eels, thereby providing a deeper insight into the role of the NP family in the acclimation of this euryhaline teleost to diverse salinity environments. PMID:21624369

  8. Similarities and differences between the massive eel (Anguilla anguilla L.) devastations that occurred in Lake Balaton in 1991 and 1995.

    PubMed

    Bálint, T; Ferenczy, J; Kátai, F; Kiss, I; Kráczer, L; Kufcsák, O; Láng, G; Polyhos, C; Szabó, I; Szegletes, T; Nemcsók, J

    1997-06-01

    In the past few years, two massive eel (Anguilla anguilla L.) devastations occurred in Lake Balaton, Hungary. In 1991, 300 tons of eel perished in the western basin of the lake, while in the summer of 1995 30 tons of eel died in the eastern part of the lake. Investigations carried out to find the causes of these ecocatastrophes included measurements of certain biochemical parameters: the blood sugar level, and the acetylcholinesterase (AChE, EC 3.1.1.7), lactate dehydrogenase (LDH, EC 1.1.2.3), glutamic-oxaloacetic transaminase (GOT, EC 2.6.1.1) and glutamic-pyruvic transaminase (GPT, EC 2.6.1.2) activities in the blood serum of the collected eels. In both 1991 and 1995, deltamethrin (DM), the active ingredient of the insecticide K-OTHRIN 1 ULV used against mosquitoes, was detected in the eels; in 1995 it was demonstrated in several other animal species, i.e., bream (Abramis brama L.), pike perch (Stizostedion lucioperca L.), and the common gull (Larus canus), and in sediment samples from the lake. Additionally, laboratory experiments were carried out to study the effects of DM on eels. In 1991, eels were collected from the western (the site of the devastation) and eastern basins of the lake. The eels from the eastern basin were used as controls. At that time, the AChE activity in the blood serum of the eels from the western basin was significantly inhibited compared to that in animals from the eastern basin (P < 0.05, Student t test). Eels from the western part of the lake had GOT and GPT levels 20 and 100%, respectively, higher than those of eels from the eastern part of the lake. The blood glucose level was much higher in the eels from the affected area of the lake as compared to those from the eastern part. The brain and liver of the eels contained DM residues at 20 micrograms/kg wet tissue (Gönczy, 1992). Gönczy suspected that one of the causes of the massive eel loss in 1991 was the presence of DM in the fish. In 1995, when the eel devastation occurred in

  9. Macroparasites and their communities of the European eel Anguilla anguilla (Linnaeus) in the Czech Republic.

    PubMed

    Moravec, Frantisek; Scholz, Tomas

    2015-01-01

    This paper summarises the results of parasitological examinations of the European eel Anguilla anguilla (Linnaeus) in the Czech Republic, carried out at the Institute of Parasitology, Czech Academy of Sciences (previously the Czechoslovak Academy of Sciences) within the period of 50 years (1958-2008). Even though this survey is limited to the Czech Republic, it provides extensive data probably incomparable with any other study anywhere regarding the number of eels examined and parasites found. A total of 723 eels was examined from 42 localities that belong to all of the three main river drainage systems in the country, i.e. the Elbe, Danube and Oder river basins. Of the 31 species of adult and larval macroparasites including Monogenea (4 species), Trematoda (3), Cestoda (3), Nematoda (11), Acanthocephala (5), Hirudinea (1), Bivalvia (1), Copepoda (1), Branchiura (1) and Acariformes (1), most of them (30) were recorded from the Elbe River basin. These parasites can be divided into three main groups regarding their host specificity: parasites specific for eels (26%), non-specific adult parasites occurring also in other fishes (61%) and non-specific larvae (13%). The highest number (19) of parasite species was recorded in the Mácha Lake fishpond system in northern Bohemia. The parasite communities in eels from the individual localities exhibited large differences in their species composition and diversity depending on local ecological conditions. The parasite fauna of A. anguilla in the Czech Republic is compared with that in other European countries. The nematode Cucullanus egyptae Abdel-Ghaffar, Bashtar, Abdel-Gaber, Morsy, Mehlhorn, Al Quraishy et Mohammed, 2014 is designated as a species inquirenda. PMID:26130652

  10. Development of a cell line from the American eel brain expressing endothelial cell properties.

    PubMed

    Bloch, Sophia R; Vo, Nguyen T K; Walsh, Sarah K; Chen, Cici; Lee, Lucy E J; Hodson, Peter V; Bols, Niels C

    2016-04-01

    A cell line (eelB) was developed from the outgrowth of adherent cells from brain explants of the American eel, Anguilla rostrata (Lesueur). EelB cells have been grown routinely in L-15 with 10% fetal bovine serum (FBS), undergone over 100 passages, and cryopreserved successfully. The cells from late-passage cultures (>45) were polygonal, formed capillary-like structures (CLS) on Matrigel, and stained immunocytochemically for von Willebrand factor (vWF) and for three tight junction proteins, zonula occludens-1 (ZO-1), claudin 3, and claudin 5. These results suggest that eelB is an endothelial cell line, one of the few from fish and the first from the brain. Despite this, eelB did not respond to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) with the induction of CYP1A protein. The cells from early-passage cultures (<20) had more varied shapes and did not form CLS on Matrigel. Only cells from early-passage cultures formed in suspension three-dimensional aggregates that had some cells expressing alkaline phosphatase and nestin. These cells are thought to be neural stem cells and the aggregates neurospheres. The emergence of endothelial-like cells upon the continued subcultivation of cells from early-passage cultures that had neural stem cells has been described previously for mammals, but this is a first for teleosts. Remarkably, cells from all passage levels were stained strongly for senescence-associated β-galactosidase (SA β-Gal) activity. PMID:26714751

  11. Seeing oxygen disorder in YSZ/SrTiO3 colossal ionic conductor heterostructures using EELS

    NASA Astrophysics Data System (ADS)

    Pennycook, T. J.; Oxley, M. P.; Garcia-Barriocanal, J.; Bruno, F. Y.; Leon, C.; Santamaria, J.; Pantelides, S. T.; Varela, M.; Pennycook, S. J.

    2011-06-01

    Colossal ionic conductivity was recently discovered in YSZ/SrTiO3 multilayers and was explained in terms of strain- and interface-enhanced disorder of the O sublattice. In the present paper we use a combination of scanning transmission electron microscopy and electron energy loss spectroscopy (EELS) and theoretical EELS simulations to confirm the presence of a disordered YSZ O sublattice in coherent YSZ/SrTiO3 multilayers. O K-edge fine structure simulated for the strained disordered O sublattice phase of YSZ possesses blurred-out features compared to that of ordered cubic bulk YSZ, and experimental EELS fine structure taken from the strained YSZ of coherent YSZ/SrTiO3 thin films is similarly blurred out. Elemental mapping is shown to be capable of resolving ordered YSZ O sublattices. Elemental mapping of O in the coherent YSZ/STO multilayers is presented in which the O sublattice is seen to be clearly resolved in the STO but blurred out in the YSZ, indicating it to be disordered. In addition, we present imaging and EELS results which show that strained regions exist at the incoherent interfaces of YSZ islands in STO with blurred out fine structure, suggesting these incoherent regions may also support high ionic conductivities. Recently, Cavallaro et al. reported electronic conductivities in samples of incoherent disconnected islands embedded in STO that are similar to the islands described herein. The presence of a region of O depleted STO at the interface with incoherent YSZ islands is revealed by EELS elemental mapping, implying the n-type doping of STO/YSZ nanocomposites with disconnected incoherent YSZ islands.

  12. Seeing Oxygen disorder in YSZ/SrTiO3 colossal ionic conductor heterostructures using EELS

    SciTech Connect

    Pennycook, Timothy J; Oxley, Mark P; Garcia-Barriocanal, Javier; Bruno, Flavio Y.; Santamaria, J.; Pantelides, Sokrates T.; Varela del Arco, Maria; Pennycook, Stephen J

    2011-01-01

    Colossal ionic conductivity was recently discovered in YSZ/SrTiO3 multilayers and was ex- plained in terms of strain and interface-enhanced disorder of the O sublattice. In the present paper we use a combination of scanning transmission electron microscopy and electron energy loss spectroscopy (EELS) and theoretical EELS simulations to confirm the presence of a disordered YSZ O sublattice in coherent YSZ/SrTiO3 multilayers. O K-edge fine structure simulated for the strained disordered O sublattice phase of YSZ possess blurred-out features compared to that of ordered cubic bulk YSZ, and experimental EELS fine structure taken from the strained YSZ of coherent YSZ/SrTiO3 thin films is similarly blurred out. Elemental mapping is shown to be capable of resolving ordered YSZ O sublattices. Elemental mapping of O in the coherent YSZ/STO multilayers is presented in which the O sublattice is seen to be clearly resolved in the STO but blurred out in the YSZ, indicating it to be disordered. In addition, we present imaging and EELS results which show that strained regions exist at the incoherent interfaces of YSZ islands in STO with blurred out fine structure suggesting these incoherent regions may also support high ionic conductivites. Recently, Cavallaro et al. reported electronic conductivities in samples of incoherent disconnected islands embedded in STO that are similar to the islands described herein. The presence of a region of O depleted STO at the interface with incoherent YSZ islands is revealed by EELS elemental mapping, implying the n-type doping of STO/YSZ nanocomposites with disconnected incoherent YSZ islands.

  13. Female condoms

    MedlinePlus

    ... female condoms at most drugstores, STI clinics, and family planning clinics. You need to plan to have a ... Jensen JT, Mishell DR. Family planning: contraception, ... Katz VL, eds. Comprehensive Gynecology . 6th ed. Philadelphia, ...

  14. Female Infertility

    MedlinePlus

    Infertility means not being able to get pregnant after at least one year of trying (or 6 ... woman keeps having miscarriages, it is also called infertility. Female infertility can result from age, physical problems, ...

  15. Silver-iron batteries

    NASA Astrophysics Data System (ADS)

    Lindstroem, O.

    1980-04-01

    Production methods for iron electrodes were studied. It was found that a sintering temperature of 700 C gave the best strength and capacity. Production methods and additions for silver electrodes were also studied. The capacity of the produced iron and silver electrodes were 1100 mAh/cu cm. Different separators were investigated. Cellophane I and II from Du Pont was found to be the best. In tests open cells achieved 60 percent of the calculated capacity. In order to minimize the increase of the pressure in closed cells different additions to the electrodes were studied.

  16. Spatial and seasonal variations of methylmercury in European glass eels (Anguilla anguilla) in the Adour estuary (France) and relation to their migratory behaviour.

    PubMed

    Claveau, Julie; Monperrus, Mathilde; Jarry, Marc; Pinaly, Herve; Baudrimont, Magalie; Gonzalez, Patrice; Amouroux, David; Bardonnet, Agnès; Bolliet, Valérie

    2015-07-01

    Overall recruitment of European glass eels (Anguilla anguilla) has decreased significantly since the early 1980s. Due to their long life cycle, benthic/demersal habits and high lipid content, eels might accumulate high concentrations of contaminants, but data concerning glass eels are still scarce. This study provides original data on methylmercury (MeHg) concentrations in glass eels at spatial (marine and estuarine), annual and seasonal scales. The relationship between MeHg concentrations in glass eels and their propensity to migrate up estuaries was also investigated. MeHg data were individually related to the eels' energetic condition which was estimated by dry weight. Glass eel migratory behaviour was investigated in an experimental flume and related to the MeHg concentration and dry weight at the individual scale. Marine and estuarine glass eels were caught from 2004 to 2011. There was a strong inverse correlation between MeHg concentrations and dry weight. MeHg concentrations increased in marine and estuarine glass eels from 2004 to 2009 and from 2004 to 2010, respectively, and then, both groups decreased in 2011. On a seasonal time scale, MeHg concentrations were higher at the end of the fishing season (April). MeHg bioaccumulation is likely to result from different sources, but the lack of significant differences between marine and estuarine glass eels suggests that direct contamination during estuarine migration is low. Other sources such as maternal transfer or oceanic contamination are discussed. PMID:25752638

  17. The molecular basis for the green-blue sensitivity shift in the rod visual pigments of the European eel.

    PubMed

    Archer, S; Hope, A; Partridge, J C

    1995-12-22

    When the European eel matures sexually and migrates back to deep sea breeding grounds the visual pigments in its rod photoreceptors change from being maximally sensitive to green light to being maximally sensitive to blue light. In part, this change in sensitivity is due to a change in the opsin component of the visual pigment molecule. We used hormone injection to induce these developmental changes in a group of eels and from these animals an opsin coding region was cloned and sequenced using cDNA made from retinal mRNA. From the retinae of hormone-injected eels and those not injected with hormones, distinct opsin mRNAs were isolated. These mRNAs encode two rod opsin proteins that are very similar but have significant amino acid substitutions in key positions that are likely to be involved in spectral tuning of the eel green and blue sensitive rod visual pigment molecules. PMID:8587887

  18. Prenatal Exposure to Silver Nanoparticles Causes Depression Like Responses in Mice

    PubMed Central

    Tabatabaei, S. R. F.; Moshrefi, M.; Askaripour, M.

    2015-01-01

    Despite increasing studies on silver nanoparticles, their mechanism of action is not so clear, especially their probable toxicity on reproduction procedure, developmental process and offspring behavior. Therefore in the present study the effect of silver nanoparticles exposure during gestational period on offspring's depression behavior was assessed. Thirty virgin female mice were divided into three groups (n=10 for each group) including: one control and two experimental groups, which received an equal volume (0.2 ml) of suspension containing 0, 0.2 and 2 mg/kg of silver nanoparticles, respectively. After mating, the suspension was injected and repeated every 3 days till accouchement. Depression behaviors were assessed by tail suspension test and forced swimming test, in 45-day-old male and female progenies (6 groups, n=10). In males, both dose of silver nanoparticles (0.2 and 2 mg/kg) decreased mobility and increased immobility time in forced swimming test (P<0.05), but in female no effects were observed in mobility and immobility time. In tail suspension test, 2 mg/kg of silver nanoparticles lead to decrease of mobility time (P<0.05) and increase of immobility time (P<0.05) in female offspring but in males no significant effect was observed on mobility and immobility time. We may concluded that the prenatal exposure to silver nanoparticles probably cause gender-specific depression like behaviors in offspring, possibly through neurotoxic effect during neuronal development. PMID:26997695

  19. RAD sequencing reveals within-generation polygenic selection in response to anthropogenic organic and metal contamination in North Atlantic Eels.

    PubMed

    Laporte, M; Pavey, S A; Rougeux, C; Pierron, F; Lauzent, M; Budzinski, H; Labadie, P; Geneste, E; Couture, P; Baudrimont, M; Bernatchez, L

    2016-01-01

    Measuring the effects of selection on the genome imposed by human-altered environment is currently a major goal in ecological genomics. Given the polygenic basis of most phenotypic traits, quantitative genetic theory predicts that selection is expected to cause subtle allelic changes among covarying loci rather than pronounced changes at few loci of large effects. The goal of this study was to test for the occurrence of polygenic selection in both North Atlantic eels (European Eel, Anguilla anguilla and American Eel, A. rostrata), using a method that searches for covariation among loci that would discriminate eels from 'control' vs. 'polluted' environments and be associated with specific contaminants acting as putative selective agents. RAD-seq libraries resulted in 23 659 and 14 755 filtered loci for the European and American Eels, respectively. A total of 142 and 141 covarying markers discriminating European and American Eels from 'control' vs. 'polluted' sampling localities were obtained using the Random Forest algorithm. Distance-based redundancy analyses (db-RDAs) were used to assess the relationships between these covarying markers and concentration of 34 contaminants measured for each individual eel. PCB153, 4'4'DDE and selenium were associated with covarying markers for both species, thus pointing to these contaminants as major selective agents in contaminated sites. Gene enrichment analyses suggested that sterol regulation plays an important role in the differential survival of eels in 'polluted' environment. This study illustrates the power of combining methods for detecting signals of polygenic selection and for associating variation of markers with putative selective agents in studies aiming at documenting the dynamics of selection at the genomic level and particularly so in human-altered environments. PMID:26562221

  20. Production and characterization of monoclonal antibodies against recombinant tethered follicle-stimulating hormone from Japanese eel Anguilla japonica.

    PubMed

    Kim, Dae-Jung; Park, Chae-Won; Kim, Dong-Wan; Park, Hong-Kyu; Byambaragchaa, Munkhzaya; Lee, Nam-Sil; Hong, Sun-Mee; Seo, Mi-Young; Kang, Myung-Hwa; Min, Kwan-Sik

    2016-07-01

    We prepared monoclonal antibodies (mAbs) against a recombinant tethered follicle-stimulating hormone (rec-FSH) from Japanese eel Anguilla japonica that was produced in Escherichia coli. Positive hybridomas (clones eFA-C5, eFA-C10, eFA-C11, eFA-C12, eFA-C13, and eFB-C14) were selected by using the eel FSH antigen in ELISA, and anti-eel FSH mAbs were purified from culture supernatants by performing affinity chromatography. Three of the 6mAbs were characterized and their isotypes were identified as IgG2b (eFA-C5 and eFA-C11) and IgG1 (eFB-C14). In western blotting assays, the mAbs recognized the antigen as a 24.3-kDa band, and further detected bands of 34 and 32kDa in the supernatants of CHO cells transfected with cDNA encoding tethered eel FSHβ/α and LHβ/α, respectively. PNase F-mediated deglycosylation of the recombinant proteins resulted in a drastic reduction in their molecular weight, to 7-9kDa. The mAbs eFA-C5 and eFA-C11 recognized the eel FSHα-subunit that is commonly encoded among glycoprotein hormones, whereas eFB-C14 recognized the eel FSHβ-subunit, and immunohistochemical analysis revealed that the staining by these mAbs was specifically localized in the eel pituitary. We also established an ELISA system for detecting rec-tethered FSHβ/α and LHβ/α produced from CHO cell lines. Measurement of biological activities in vitro revealed that only weak activity of rec-FSHβ/α was detected. The activity of rec-LHβ/α was found to be increased in a dose-dependent manner for eel oocyte maturation. PMID:27174750

  1. The effects of five different glycans on innate immune responses by phagocytes of hybrid tilapia and Japanese eels Anguilla japonica.

    PubMed

    Wang, Way-Shyan; Hung, Shao-Wen; Lin, Yu-Hsing; Tu, Ching-Yu; Wong, Min-Liang; Chiou, Shiow-Her; Shieh, Meng-Tong

    2007-03-01

    The aim of this study was to evaluate the immune responses in hybrid tilapia (Nile tilapia Oreochromis niloticus x Mozambique tilapia O. mossambicus) and Japanese eels Anguilla japonica after treatment with five glycans: barley, krestin, MacroGard, scleroglucan, and zymosan. The effects of the glycans on the innate immune responses of the fish were investigated using the phagocytic index (PI), lysozyme activity, complement opsonization, and activation assay. The results of the lysozyme assay demonstrated that the lysozyme activities increased after treatment with glycans. Moreover, based on the PI, treatment with each of the five glycans resulted in increased phagocytic activities in anterior kidney and peripheral blood phagocytes in both tilapia and Japanese eels. The opsonic effect of complement on phagocytosis in tilapia and Japanese eels were investigated using baker's yeast, which served as the activator in the classical complement pathway (CCP) and in the alternative complement pathway (ACP). Tilapia and Japanese eel sera that were treated with glycans greatly enhanced phagocytosis. The classical pathway--hemolytic complement titer (CH50) of Japanese eels treated with glycans was slightly increased in vitro and in vivo. While glycan treatment enhanced the CCP of both species in vitro and in vivo, the alternative pathway-hemolytic complement titer (ACH50) was only increased in vitro and in vivo in glycan-treated tilapia. Thus, it follows that the ACP must have been activated in tilapia treated with glycans. However, in Japanese eels, the ACH50 of the ACP activation assay was undetected in vitro or in vivo due to possible unknown factors in the Japanese eel serum that caused lysis of the rabbit red blood cells. Our study investigated the effects of glycans used to enhance phagocytosis and activate both of the complement pathways involved in stimulating the innate immune responses of Japanese eels and tilapia. PMID:18236632

  2. Tales From Silver Lands.

    ERIC Educational Resources Information Center

    Finger, Charles J.

    In 1925, "Tales From Silver Lands" was awarded the Newbery medal as the most distinguished contribution to American children's literature for the year. The book contains a collection of 19 short stories learned from the Indians of South America as the author traveled to different lands. As described on the dust jacket, the tales are about "strange…

  3. Potassium silver cyanide

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 28 , 2010 , the assessment summary for potassium silver cyanide is inclu

  4. Fe and O EELS Studies of Ion Irradiated Murchison CM2 Carbonaceous Chondrite Matrix

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Christofferson, R.; Dukes, C. A.; Baragiola, R. A.; Rahman, Z.

    2015-01-01

    Introduction: The physical and chemical response of hydrated carbonaceous chondrite materials to space weathering processes is poorly understood. Improving this understanding is a key part of establishing how regoliths on primitive carbonaceous asteroids respond to space weathering processes, knowledge that supports future sample return missions (Hayabusa 2 and OSIRISREx) that are targeting objects of this type. We previously reported on He+ irradiation of Murchison matrix and showed that the irradiation resulted in amorphization of the matrix phyllosilicates, loss of OH, and surface vesiculation. Here, we report electron energy-loss spectroscopy (EELS) measurements of the irradiated material with emphasis on the Fe and O speciation. Sample and Methods: A polished thin section of the Murchison CM2 carbonaceous chondrite was irradiated with 4 kilovolts He(+) (normal incidence) to a total dose of 1 x 10(exp 18) He(+) per square centimeter. We extracted thin sections from both irradiated and unirradiated regions in matrix using focused ion beam (FIB) techniques with electron beam deposition for the protective carbon strap to minimize surface damage artifacts from the FIB milling. The FIB sections were analyzed using a JEOL 2500SE scanning and transmission electron microscope (STEM) equipped with a Gatan Tridiem imaging filter. EELS spectra were collected from 50 nanometer diameter regions with an energy resolution of 0.7 electronvolts FWHM at the zero loss. EELS spectra were collected at low electron doses to minimize possible artifacts from electron-beam irradiation damage. Results and Discussion: Fe L (sub 2,3) EELS spectra from matrix phyllosilicates in CM chondrites show mixed Fe(2+)/Fe(3+) oxidation states with Fe(3+)/Sigma Fe approximately 0.5. Fe L(sub 2,3) spectra from the irradiated/ amorphized matrix phyllosilicates show higher Fe(2+)/Fe(3+) ratios compared to spectra obtained from pristine material at depths beyond the implantation/amorphization layer. We

  5. Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

    NASA Astrophysics Data System (ADS)

    Kvitek, L.; Panacek, A.; Prucek, R.; Soukupova, J.; Vanickova, M.; Kolar, M.; Zboril, R.

    2011-07-01

    The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

  6. Richness and diversity of helminth species in eels from a hypersaline coastal lagoon, Mar Menor, south-east Spain.

    PubMed

    Mayo-Hernández, E; Peñalver, J; García-Ayala, A; Serrano, E; Muñoz, P; Ruiz de Ybáñez, R

    2015-05-01

    The composition and diversity of parasite communities and intestinal components, as well as infra-community structure, were assessed in eels Anguilla anguilla, from Mar Menor, a permanent Mediterranean hypersaline coastal lagoon. Data were used to determine whether this helminth community differs in composition and structure from that of eels in lagoons with lower salinity regimes and higher freshwater inputs. A total prevalence of 93% was detected. Specifically, parasites were identified as Deropristis inflata, Bucephalus anguillae, Contracaecum sp., Anguillicoloides crassus and two plerocercoid larvae belonging to the order Proteocephalidae, the marine species representing 91% of the isolated helminths. In the total community, digenetic trematodes were the dominant group of helminths, and D. inflata, an eel specialist, dominated both the component community and the infra-community. Richness and diversity were low but similar to those reported in other saline lagoons, and maximum species per eel did not exceed four. At the infra-community level, higher abundance than in other brackish or marine Mediterranean environments was detected. The findings provide further evidence of the similarity in composition and structure of helminth communities in eels from various Mediterranean coastal lagoons. Moreover, salinity-dependent specificities are well supported and reflect the life history of individual eels. PMID:24685015

  7. Bioaccumulation, biotransformation and DNA binding of PAHs in feral eel (Anguilla anguilla) exposed to polluted sediments: A field survey

    SciTech Connect

    Oost, R. Van Der; Heida, H.; Satumalay, K. ); Schooten, F.J. Van . Dept. of Health Risk Analysis and Toxicology); Ariese, F.; Vermeulen, N.P.E. )

    1994-06-01

    Samples of sediment and eel taken from six sites in Amsterdam with different levels of water pollution were analyzed for 16 parental PAHs. In addition, biliary PAH metabolites and hepatic PAH-DNA adducts were determined in the eel to evaluate biomonitoring techniques for PAH exposure. There was a clear difference between PAH profiles in sediments and eel. Mainly two- and three-ring PAHs were detected in eel, whereas four-ring PAHs predominated in the sediments. Because PAH bioaccumulation was highest in eel from the reference sites, tissue levels of the parental PAH are probably not the most accurate monitor of PAH exposure in fish. An elevated excretion of 1-OH pyrene (determined by synchronous scan fluorescence) was observed in the bile of fish from three of the four polluted sites, indicating that this parameter may be used as a biomarker for PAH exposure. A significant increase in PAH-DNA adduct levels was observed in the liver of eel from all polluted sites. Therefore, this parameter seems to be a sensitive biomarker for exposure to mutagenic and carcinogenic PAHs.

  8. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (north Atlantic): American eel. [Anguilla rostrata

    SciTech Connect

    Facey, D.E.; Van Den Avyle, M.J.

    1987-08-01

    The American eel is an ecologically and economically important catadromous species that occupies freshwater streams, rivers, brackish estuaries, and the open ocean during various phases of its life cycle. Adult eels apparently spawn in the Sargasso Sea, and ocean currents transport the developing larvae northward until the young metamorphose into juveniles capable of swimming shoreward and moving upstream into coastal areas, estuaries, and rivers. Developing eels commonly remain in freshwater or brackish areas for 10-12 years before migrating to spawn. American eels tend to be bottom-dwellers and feed on a variety of fauna that occupy the same habitats. Eels occupy areas having wide ranges of temperature, salinity, and other environmental factors, suggesting broad tolerance limits, but few studies of requirements have been reported. Salinity patterns and water currents created by river discharges into coastal areas apparently provide the gradient that cues shoreward migration of juvenile eels. Alteration of patterns of freshwater inflows to estuaries and bays could affect upstream migrations.

  9. Characterization of Electrochemically Generated Silver

    NASA Technical Reports Server (NTRS)

    Adam, Niklas; Martinez, James; Carrier, Chris

    2014-01-01

    Silver biocide offers a potential advantage over iodine, the current state of the art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. Low concentrations of silver (<500 ppb) have been shown to kill bacteria in water systems and keep it safe for potability. Silver does not require hardware to remove it from a water system, and therefore can provide a simpler means for disinfecting water. The Russian segment of the International Space Station has utilized an electrochemically generated silver solution, which is colloidal in nature. To be able to reliably provide a silver biocide to drinking water by electrochemical means would reduce mass required for removing another biocide such as iodine from the water. This would also aid in crew time required to replace iodine removal cartridges. Future long term missions would benefit from electrochemically produced silver as the biocide could be produced on demand and requires only a small concentration to be effective. Since it can also be consumed safely, there is less mass in removal hardware and little consumables required for production. The goal of this project initially is to understand the nature of the electrochemically produced silver, the particle sizes produced by the electrochemical cell and the effect that voltage adjustment has on the particle size. In literature, it has been documented that dissolved oxygen and pH have an effect on the ionization of the electrochemical silver so those parameters would be measured and possibly adjusted to understand their effect on the silver.

  10. A Mid-Upper Palaeolithic human humerus from Eel Point, South Wales, UK.

    PubMed

    Schulting, Rick J; Trinkaus, Erik; Higham, Tom; Hedges, Robert; Richards, Michael; Cardy, Bernice

    2005-05-01

    We report here on a human humerus directly dated to 24,470 +/- 110 BP, placing it within the Gravettian, or Mid-Upper Palaeolithic. The partial humerus is an isolated find and can be attributed (with some caution) to the Pleistocene 'bone cave' of Eel Point on Caldey Island, Wales (UK). The humerus is probably male, similar in robusticity to other Gravettian right humeri. The apparent absence of stone tools and presence of hyaena bone and coprolites suggest that the element may not derive from an intentional burial. After a maxilla from Kent's Cavern and the Gravettian Paviland 1, Eel Point represents the third oldest anatomically modern human known from Britain. Stable carbon and nitrogen isotope measurements do not support certain use of marine foods but highlight the need for more research on contemporary faunal remains in order to better interpret human values from this period. PMID:15857652

  11. Uranium-series age of the Eel Point terrace, San Clemente Island, California

    SciTech Connect

    Muhs, D.R.; Szabo, B.J.

    1982-01-01

    Uranium-series analysis of the coral Allopora californica Verrill from the 2nd, 32-m Eel Point terrace on San Clemente Island, California, has yielded an age of 127,000 +/- 7,000 yr. The Eel Point terrace is thus correlative with numerous terrace localities on the southern California mainland, with coral reefs on Barbados and New Guinea dated about 120,000 yr, and with substage 5e of the marine oxygen-isotope record. A tectonic uplift rate of about 0.20 m/1,000 yr has been calculated assuming a sea level slightly higher than the present one at the time of terrace formation. Extrapolation of this uplift rate allows age estimates to be made for other terraces on the island.

  12. Growth patterns and age validation from otolith ring deposition in New Zealand longfin eels Anguilla dieffenbachii recaptured after 10 years at large.

    PubMed

    Beentjes, M P; Jellyman, D J

    2015-03-01

    In 1998, 9500 juvenile New Zealand longfin eels Anguilla dieffenbachii (mean total length, LT , 42 cm) captured from the lower Clutha River were transferred upstream to Lake Hawea, a high-country oligotrophic lake in the same catchment where recruitment of juvenile eels has been prevented by hydroelectric dams since 1958. A total of 2010 of the transferred A. dieffenbachii were tagged with coded wire tags. Ten years later in 2008, the A. dieffenbachii population in Lake Hawea was sampled resulting in 399 recaptures (distinguishable by the presence of tags and by LT from the remnant resident population of large old A. dieffenbachii) of the 1998 transfers; 79 (19·2%) of the recaptured fish had tags compared with 21·3% at release, indicating good tag retention and low mortality due to tagging. All recaptured tagged A. dieffenbachii were female. Mean annual growth over the 10 years since release was 3·80 cm year(-1) for all recaptures and 3·65 cm year(-1) for tag recaptures, and both were significantly greater than the estimate of 2·38 cm year(-1) at release. After release, mean condition (K) increased significantly (P < 0·001) for all recaptures and tag recaptures. Annual length growth increment was linear. Tag recaptures showed significant increases in somatic growth rate post-transfer, and otoliths from the 2008 recaptured A. dieffenbachii were examined to see whether any similar enhanced growth after transfer was incorporated into the otolith structure that would serve as a date stamp. Measurement of otolith ring radii indicated that an increase in the radius occurred on most otoliths corresponding to the year after transfer. Because there was 9 years of completed growth following the observed growth inflection on the otoliths, this was strong evidence that opaque rings were formed annually. PMID:25644125

  13. Phylogeography of two moray eels indicates high dispersal throughout the indo-pacific.

    PubMed

    Reece, Joshua S; Bowen, Brian W; Joshi, Kavita; Goz, Vadim; Larson, Allan

    2010-01-01

    Reef fishes disperse primarily as oceanic "pelagic" larvae, and debate continues over the extent of this dispersal, with recent evidence for geographically restricted (closed) populations in some species. In contrast, moray eels have the longest pelagic larval stages among reef fishes, possibly providing opportunities to disperse over great distances. We test this prediction by measuring mitochondrial DNA (mtDNA) and nuclear DNA variation in 2 species of moray eels, Gymnothorax undulatus (N = 165) and G. flavimarginatus (N = 124), sampled at 14-15 locations across the Indo-Pacific. The mtDNA data comprise 632 bp of cytochrome b and 596 bp of cytochrome oxidase I. Nuclear markers include 2 recombination-activating loci (421 bp of RAG-1 and 754 bp of RAG-2). Analyses of molecular variance and Mantel tests indicate little or no genetic differentiation, and no isolation by distance, across 22 000 km of the Indo-Pacific. We estimate that mitochondrial genetic variation coalesces within the past about 2.3 million years (My) for G. flavimarginatus and within the past about 5.9 My for G. undulatus. Permutation tests of geographic distance on the mitochondrial haplotype networks indicate recent range expansions for some younger haplotypes (estimated within approximately 600 000 years) and episodic fragmentation of populations at times of low sea level. Our results support the predictions that the extended larval durations of moray eels enable ocean-wide genetic continuity of populations. This is the first phylogeographic survey of the moray eels, and morays are the first reef fishes known to be genetically homogeneous across the entire Indo-Pacific. PMID:20375076

  14. Phylogeography of Two Moray Eels Indicates High Dispersal Throughout the Indo-Pacific

    PubMed Central

    Bowen, Brian W.; Joshi, Kavita; Goz, Vadim; Larson, Allan

    2010-01-01

    Reef fishes disperse primarily as oceanic “pelagic” larvae, and debate continues over the extent of this dispersal, with recent evidence for geographically restricted (closed) populations in some species. In contrast, moray eels have the longest pelagic larval stages among reef fishes, possibly providing opportunities to disperse over great distances. We test this prediction by measuring mitochondrial DNA (mtDNA) and nuclear DNA variation in 2 species of moray eels, Gymnothorax undulatus (N = 165) and G. flavimarginatus (N = 124), sampled at 14–15 locations across the Indo-Pacific. The mtDNA data comprise 632 bp of cytochrome b and 596 bp of cytochrome oxidase I. Nuclear markers include 2 recombination-activating loci (421 bp of RAG-1 and 754 bp of RAG-2). Analyses of molecular variance and Mantel tests indicate little or no genetic differentiation, and no isolation by distance, across 22 000 km of the Indo-Pacific. We estimate that mitochondrial genetic variation coalesces within the past about 2.3 million years (My) for G. flavimarginatus and within the past about 5.9 My for G. undulatus. Permutation tests of geographic distance on the mitochondrial haplotype networks indicate recent range expansions for some younger haplotypes (estimated within ∼600 000 years) and episodic fragmentation of populations at times of low sea level. Our results support the predictions that the extended larval durations of moray eels enable ocean-wide genetic continuity of populations. This is the first phylogeographic survey of the moray eels, and morays are the first reef fishes known to be genetically homogeneous across the entire Indo-Pacific. PMID:20375076

  15. Role of calcium on the initiation of sperm motility in the European eel.

    PubMed

    Pérez, Luz; Vílchez, M Carmen; Gallego, Víctor; Morini, Marina; Peñaranda, David S; Asturiano, Juan F

    2016-01-01

    Sperm from European eel males treated with hCGrec was washed in a calcium free extender, and sperm motility was activated both in the presence (seawater, SW) and in the absence of calcium (NaCl+EDTA), and treated with calcium inhibitors or modulators. The sperm motility parameters were evaluated by a computer-assisted sperm analysis (CASA) system, and changes in the [Ca(2+)]i fluorescence (and in [Na(+)]i in some cases) were evaluated by flow cytometry. After sperm motility was activated in a medium containing Ca(2+) (seawater, SW) the intracellular fluorescence emitted by Ca(2+) increased 4-6-fold compared to the levels in quiescent sperm. However, while sperm activation in a Ca-free media (NaCl+EDTA) resulted in a percentage of motility similar to seawater, the [Ca(2+)]i levels did not increase at all. This result strongly suggests that increasing [Ca(2+)]i is not a pre-requisite for the induction of sperm motility in European eel sperm. Several sperm velocities (VCL, VSL, VAP) decreased when sperm was activated in the Ca-free activator, thus supporting the theory that Ca(2+) has a modulatory effect on sperm motility. The results indicate that a calcium/sodium exchanger (NCX) which is inhibited by bepridil and a calcium calmodulin kinase (inhibited by W-7), are involved in the sperm motility of the European eel. Our results indicate that the increase in [Ca(2+)]i concentrations during sperm activation is due to an influx from the external medium, but, unlike in most other species, it does not appear to be necessary for the activation of motility in European eel sperm. PMID:26459984

  16. Is there a Stobbs factor in atomic-resolution STEM-EELS mapping?

    PubMed

    Xin, Huolin L; Dwyer, Christian; Muller, David A

    2014-04-01

    Recent work has convincingly argued that the Stobbs factor-disagreement in contrast between simulated and experimental atomic-resolution images-in ADF-STEM imaging can be accounted for by including the incoherent source size in simulation. However, less progress has been made for atomic-resolution STEM-EELS mapping. Here we have performed carefully calibrated EELS mapping experiments of a [101] DyScO3 single-crystal specimen, allowing atomic-resolution EELS signals to be extracted on an absolute scale for a large range of thicknesses. By simultaneously recording the elastic signal, also on an absolute scale, and using it to characterize the source size, sample thickness and inelastic mean free path, we eliminate all free parameters in the simulation of the core-loss signals. Coupled with double channeling simulations that incorporate both core-loss inelastic scattering and dynamical elastic and thermal diffuse scattering, the present work enables a close scrutiny of the scattering physics in the inelastic channel. We found that by taking into account the effective source distribution determined from the ADF images, both the absolute signal and the contrast in atomic-resolution Dy-M5 maps can be closely reproduced by the double-channeling simulations. At lower energy losses, discrepancies are present in the Sc-L2,3 and Dy-N4,5 maps due to the energy-dependent spatial distribution of the background spectrum, core-hole effects, and omitted complexities in the final states. This work has demonstrated the possibility of using quantitative STEM-EELS for element-specific column-by-column atom counting at higher energy losses and for atomic-like final states, and has elucidated several possible improvements for future theoretical work. PMID:24561427

  17. Natural selection influences AFLP intraspecific genetic variability and introgression patterns in Atlantic eels.

    PubMed

    Gagnaire, P A; Albert, V; Jónsson, B; Bernatchez, L

    2009-04-01

    Investigating patterns of genetic variation in hybridizing species provides an opportunity to understand the impact of natural selection on intraspecific genetic variability and interspecific gene exchange. The Atlantic eels Anguilla rostrata and A. anguilla each occupy a large heterogeneous habitat upon which natural selection could differentially shape genetic variation. They also produce viable hybrids only found in Iceland. However, the possible footprint of natural selection on patterns of genetic variation within species and introgressive hybridization in Icelandic eels has never been assessed. We revisited amplified fragment length polymorphism data collected previously using population genomics and admixture analyses to test if (i) genetic variation could be influenced by non-neutral mechanisms at both the intra- and interspecific levels, and if (ii) selection could shape the spatio-temporal distribution of Icelandic hybrids. We first found candidate loci for directional selection within both species. Spatial distributions of allelic frequencies displayed by some of these loci were possibly related with the geographical patterns of life-history traits in A. rostrata, and could have been shaped by natural selection associated with an environmental gradient along European coasts in A. anguilla. Second, we identified outlier loci at the interspecific level. Non-neutral introgression was strongly suggested for some of these loci. We detected a locus at which typical A. rostrata allele hardly crossed the species genetic barrier, whereas three other loci showed accelerated patterns of introgression into A. anguilla in Iceland. Moreover, the level of introgression at these three loci increased from the glass eel to the yellow eel stage, supporting the hypothesis that differential survival of admixed genotypes partly explains the spatio-temporal pattern of hybrid abundance previously documented in Iceland. PMID:19302349

  18. Hydrometallurgical recovery of silver from waste silver oxide button cells

    NASA Astrophysics Data System (ADS)

    Sathaiyan, N.; Nandakumar, V.; Ramachandran, P.

    In recent years, recycling of household batteries has attracted much attention mainly with respect to environmental aspects in addition to the savings. Small silver oxide primary cells used in electric watches become a waste after their life is over. Recycling procedures are needed to prevent any environmental impact from these wastes and to recover the value inherent in the scrap. Smelting and electrolytic methods are discussed for silver recovery from this battery waste. Acid leaching of waste batteries and precipitation of silver as silver chloride followed by smelting at 1000 °C yields a silver recovery of about 83%. An electrolytic route is studied as an alternative to the smelting operation and involves the electrodeposition of silver with higher purity from a silver thiosulfate complex prepared from silver chloride. The electrolysis is potentiostatically controlled at a potential of -0.400 to -0.600 V (SCE) for avoiding side-reactions such as the sulfiding of silver. Although recovery methods have been identified in principle, their suitability for mixed small battery waste and economic factors have yet to be demonstrated.

  19. Molecular cloning and characterization analysis of immunoglobulin M heavy chain gene in European eel (Anguilla anguilla).

    PubMed

    Feng, Jianjun; Guan, Ruizhang; Lin, Peng; Guo, Songlin

    2009-01-15

    In this study, the immunoglobulin M heavy chain gene of European eel (Anguilla anguilla) was cloned and analyzed. The full-length cDNA of the IgM heavy chain gene (GenBank accession no. EF062515) has 2089 nucleotides encoding a putative protein of 581 amino acids. The IgM heavy chain was composed of leader peptide (L), variable domain (VH), CH1, CH2, Hinge, CH3, CH4, and C-terminus and two novel continuous putative N-glycosylation sites were found close to the second cysteine of CH3 in A. anguilla-H1 and A. anguilla-H2. The deduced amino acid sequence of the European eel IgM heavy chain constant region shared similarities to that of the Ladyfish (Elops saurus), Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), Grass carp (Ctenopharingodon idella), Common carp (Cyprinus carpio), Channel catfish (Ictalurus punctatus), and the orange-spotted grouper (Epinephelus coioides) with the identity of 46.1%, 39.7%, 38.9%, 32.4%, 32.3%, 31.7%, and 30.7%, respectively. The highest level of IgM gene expression was observed in the kidney, followed by the spleen, gills, liver, muscle and heart in the apparently healthy European eels. PMID:19013650

  20. The genetic consequences of spatially varying selection in the panmictic American eel (Anguilla rostrata).

    PubMed

    Gagnaire, Pierre-Alexandre; Normandeau, Eric; Côté, Caroline; Møller Hansen, Michael; Bernatchez, Louis

    2012-02-01

    Our understanding of the genetic basis of local adaptation has recently benefited from the increased power to identify functional variants associated with environmental variables at the genome scale. However, it often remains challenging to determine whether locally adaptive alleles are actively maintained at intermediate frequencies by spatially varying selection. Here, we evaluate the extent to which this particular type of balancing selection explains the retention of adaptive genetic variation in the extreme situation of perfect panmixia, using the American eel (Anguilla rostrata) as a model. We first conducted a genome scan between two samples from opposite ends of a latitudinal environmental gradient using 454 sequencing of individually tagged cDNA libraries. Candidate SNPs were then genotyped in 992 individuals from 16 sampling sites at different life stages of the same cohort (including larvae from the Sargasso Sea, glass eels, and 1-year-old individuals) as well as in glass eels of the following cohort. Evidence for spatially varying selection was found at 13 loci showing correlations between allele frequencies and environmental variables across the entire species range. Simulations under a multiple-niche Levene's model using estimated relative fitness values among genotypes rarely predicted a stable polymorphic equilibrium at these loci. Our results suggest that some genetic-by-environment interactions detected in our study arise during the progress toward fixation of a globally advantageous allele with spatially variable effects on fitness. PMID:22135355

  1. Transcriptomic profiling of male European eel (Anguilla anguilla) livers at sexual maturity.

    PubMed

    Churcher, Allison M; Pujolar, Jose Martin; Milan, Massimo; Huertas, Mar; Hubbard, Peter C; Bargelloni, Luca; Patarnello, Tomaso; Marino, Ilaria A M; Zane, Lorenzo; Canário, Adelino V M

    2015-12-01

    The European eel Anguilla anguilla has a complex life cycle that includes freshwater, seawater and morphologically distinct stages as well as two extreme long distance migrations. Eels do not feed as they migrate across the Atlantic to the Sargasso Sea but nevertheless reach sexual maturity before spawning. It is not yet clear how existing energy stores are used to reach the appropriate developmental state for reproduction. Since the liver is involved in energy metabolism, protein biosynthesis and endocrine regulation it is expected to play a key role in the regulation of reproductive development. We therefore used microarrays to identify genes that may be involved in this process. Using this approach, we identified 231 genes that were expressed at higher and 111 genes that were expressed at lower levels in sexually mature compared with immature males. The up-regulated set includes genes involved in lipid metabolism, fatty acid synthesis and transport, mitochondrial function, steroid transport and bile acid metabolism. Several genes with putative enzyme functions were also expressed at higher levels at sexual maturity while genes involved in immune system processes and protein biosynthesis tended to be down-regulated at this stage. By using a high-throughput approach, we have identified a subset of genes that may be linked with the mobilization of energy stores for sexual maturation and migration. These results contribute to an improved understanding of eel reproductive biology and provide insight into the role of the liver in other teleosts with a long distance spawning migrations. PMID:26253995

  2. Sequencing and de novo assembly of the red cusk-eel (Genypterus chilensis) transcriptome.

    PubMed

    Aedo, J E; Maldonado, J; Estrada, J M; Fuentes, E N; Silva, H; Gallardo-Escarate, C; Molina, A; Valdés, J A

    2014-12-01

    The red cusk-eel (Genypterus chilensis) is an endemic fish species distributed along the coasts of the Eastern South Pacific. Biological studies on this fish are scarce, and genomic information for G. chilensis is practically non-existent. Thus, transcriptome information for this species is an essential resource that will greatly enrich molecular information and benefit future studies of red cusk-eel biology. In this work, we obtained transcriptome information of G. chilensis using the Illumina platform. The RNA sequencing generated 66,307,362 and 59,925,554 paired-end reads from skeletal muscle and liver tissues, respectively. De novo assembly using the CLC Genomic Workbench version 7.0.3 produced 48,480 contigs and created a reference transcriptome with a N50 of 846bp and average read coverage of 28.3×. By sequence similarity search for known proteins, a total of 21,272 (43.9%) contigs were annotated for their function. Out of these annotated contigs, 33.5% GO annotation results for biological processes, 32.6% GO annotation results for cellular components and 34.5% GO annotation results for molecular functions. This dataset represents the first transcriptomic resource for the red cusk-eel and for a member of the Ophidiimorpharia taxon. PMID:25139027

  3. The Genetic Consequences of Spatially Varying Selection in the Panmictic American Eel (Anguilla rostrata)

    PubMed Central

    Gagnaire, Pierre-Alexandre; Normandeau, Eric; Côté, Caroline; Møller Hansen, Michael; Bernatchez, Louis

    2012-01-01

    Our understanding of the genetic basis of local adaptation has recently benefited from the increased power to identify functional variants associated with environmental variables at the genome scale. However, it often remains challenging to determine whether locally adaptive alleles are actively maintained at intermediate frequencies by spatially varying selection. Here, we evaluate the extent to which this particular type of balancing selection explains the retention of adaptive genetic variation in the extreme situation of perfect panmixia, using the American eel (Anguilla rostrata) as a model. We first conducted a genome scan between two samples from opposite ends of a latitudinal environmental gradient using 454 sequencing of individually tagged cDNA libraries. Candidate SNPs were then genotyped in 992 individuals from 16 sampling sites at different life stages of the same cohort (including larvae from the Sargasso Sea, glass eels, and 1-year-old individuals) as well as in glass eels of the following cohort. Evidence for spatially varying selection was found at 13 loci showing correlations between allele frequencies and environmental variables across the entire species range. Simulations under a multiple-niche Levene’s model using estimated relative fitness values among genotypes rarely predicted a stable polymorphic equilibrium at these loci. Our results suggest that some genetic-by-environment interactions detected in our study arise during the progress toward fixation of a globally advantageous allele with spatially variable effects on fitness. PMID:22135355

  4. Uptake and elimination of cadmium by Japanese Eel, Anguilla japonica, at various temperatures

    SciTech Connect

    Yang, H.N.; Chen, H.C.

    1996-04-01

    There is no evidence that cadmium is biologically essential, but its toxicity to organisms is well known. The so-called Itai-Itai disease in Japan, characterized by osteomalacia and renal tubular malfunction, has been attributed to cadmium poisoning in irrigation water. The degree of contamination in aquatic environments is frequently assessed by comparing contaminant concentrations in associated biota. Bioaccumulation, however, is influenced by environmental factors other than the degree of contamination, environmental factors such as salinity, temperature and pH. The use of cadmium in the electroplating industry in Taiwan is intensive, but the wastewater used in this industry is seldom treated and has been a serious problem. The Japanese eel (Anguilla japonica) is an important freshwater aquacultural fish in Taiwan; thus, it is important to know the accumulation and elimination of cadmium in the Japanese eel due to cadmium-polluted water at various temperatures in order to protect eel resources as well as human health. 18 refs., 3 figs., 1 tab.

  5. Direct calorimetry of free-moving eels with manipulated thyroid status

    NASA Astrophysics Data System (ADS)

    van Ginneken, Vincent; Ballieux, Bart; Antonissen, Erik; van der Linden, Rob; Gluvers, Ab; van den Thillart, Guido

    2007-02-01

    In birds and mammals, the thyroid gland secretes the iodothyronine hormones of which tetraiodothyronine (T4) is less active than triiodothyronine (T3). The action of T3 and T4 is calorigenic and is involved in the control of metabolic rate. Across all vertebrates, thyroid hormones also play a major role in differentiation, development and growth. Although the fish thyroidal system has been researched extensively, its role in thermogenesis is unclear. In this study, we measured overall heat production to an accuracy of 0.1 mW by direct calorimetry in a free-moving European eel ( Anguilla anguilla L.) with different thyroid status. Hyperthyroidism was induced by injection of T3 and T4, and hypothyroidism was induced with phenylthiourea. The results show for the first time at the organismal level, using direct calorimetry, that neither overall heat production nor overall oxygen consumption in eels is affected by hyperthyroidism. Therefore, we conclude that the thermogenic metabolism-stimulating effect of thyroid hormones (TH) is not present with a cold-blooded fish species like the European eel. This supports the concept that TH does not stimulate thermogenesis in poikilothermic species.

  6. Fipronil and two of its transformation products in water and European eel from the river Elbe.

    PubMed

    Michel, N; Freese, M; Brinkmann, M; Pohlmann, J-D; Hollert, H; Kammann, U; Haarich, M; Theobald, N; Gerwinski, W; Rotard, W; Hanel, R

    2016-10-15

    Fipronil is an insecticide which, based on its mode of action, is intended to be predominantly toxic towards insects. Fipronil bioaccumulates and some of its transformation products were reported to be similar or even more stable in the environment and to show an enhanced toxicity against non-target organisms compared to the parent compound. The current study investigated the occurrence of Fipronil and two of its transformation products, Fipronil-desulfinyl and Fipronil-sulfone, in water as well as muscle and liver samples of eels from the river Elbe (Germany). In water samples total concentrations of FIP, FIP-d and FIP-s ranged between 0.5-1.6ngL(-1) with FIP being the main component in all water samples followed by FIP-s and FIP-d. In contrast, FIP-s was the main component in muscle and liver tissues of eels with concentrations of 4.05±3.73ngg(-1) ww and 19.91±9.96ngg(-1) ww, respectively. Using a physiologically based toxicokinetic (PBTK) model for moderately hydrophobic organic chemicals, the different distributions of FIP, FIP-d and FIP-s in water and related tissue samples could be attributed to metabolic processes of eels. The measured concentrations in water of all analytes and their fractional distribution did not reflect the assumed seasonal application of FIP and it seems that the water was constantly contaminated with FIP, FIP-d and FIP-s. PMID:27289396

  7. EELS Analysis of Nylon 6 Nanofibers Reinforced with Nitroxide-Functionalized Graphene Oxide.

    PubMed

    Leyva-Porras, César; Ornelas-Gutiérrez, C; Miki-Yoshida, M; Avila-Vega, Yazmín I; Macossay, Javier; Bonilla-Cruz, José

    2014-01-01

    A detailed analysis by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) of nitroxide-functionalized graphene oxide layers (GOFT) dispersed in Nylon 6 nanofibers is reported herein. The functionalization and exfoliation process of graphite oxide to GOFT was confirmed by TEM using electron diffraction patterns (EDP), wherein 1 to 4 graphene layers of GOFT were observed. The distribution and alignment of GOFT layers within a sample of Nylon 6 nanofiber reveals that GOFT platelets are mainly within the fiber, but some were partially protruding from it. Furthermore, Nylon 6 nanofibers exhibit an average diameter of 225 nm with several microns in length. GOFT platelets embedded into the fiber, the pristine fiber, and amorphous carbon were analyzed by EELS where each spectra [corresponding to the carbon edge (C-K)] exhibited changes in the fine structure, allowing a clear distinction between: i) GOFT single-layers, ii) Nylon-6 nanofibers, and iii) the carbon substrate. EELS analysis is presented here for the first time as a powerful tool to identify functionalized graphene single-layers (< 4 layers of GOFT) into a Nylon 6 nanofiber composite. PMID:24634536

  8. EELS Analysis of Nylon 6 Nanofibers Reinforced with Nitroxide-Functionalized Graphene Oxide

    PubMed Central

    Leyva-Porras, César; Ornelas-Gutiérrez, C.; Miki-Yoshida, M.; Avila-Vega, Yazmín I.; Macossay, Javier; Bonilla-Cruz, José

    2014-01-01

    A detailed analysis by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) of nitroxide-functionalized graphene oxide layers (GOFT) dispersed in Nylon 6 nanofibers is reported herein. The functionalization and exfoliation process of graphite oxide to GOFT was confirmed by TEM using electron diffraction patterns (EDP), wherein 1 to 4 graphene layers of GOFT were observed. The distribution and alignment of GOFT layers within a sample of Nylon 6 nanofiber reveals that GOFT platelets are mainly within the fiber, but some were partially protruding from it. Furthermore, Nylon 6 nanofibers exhibit an average diameter of 225 nm with several microns in length. GOFT platelets embedded into the fiber, the pristine fiber, and amorphous carbon were analyzed by EELS where each spectra [corresponding to the carbon edge (C-K)] exhibited changes in the fine structure, allowing a clear distinction between: i) GOFT single-layers, ii) Nylon-6 nanofibers, and iii) the carbon substrate. EELS analysis is presented here for the first time as a powerful tool to identify functionalized graphene single-layers (< 4 layers of GOFT) into a Nylon 6 nanofiber composite. PMID:24634536

  9. Molecular characterization of Aeromonas species isolated from farmed eels (Anguilla japonica).

    PubMed

    Yi, Seung-Won; You, Myung-Jo; Cho, Ho-Seong; Lee, Chang-Seop; Kwon, Joong-Ki; Shin, Gee-Wook

    2013-05-31

    Seventy Aeromonas strains were identified by phylogenetic analysis using housekeeping genes (gyrB and rpoD) in order to investigate etiological agents for aeromoniasis in farmed eels (Anguilla japonica). The phylogenetic analysis showed that Aeromonas aquariorum (n=22, 31.4%) was the predominant species among the investigated eel strains, followed by Aeromonas caviae (n=16, 22.9%), A. veronii (n=13, 18.6%), A. hydrophila (n=12, 17.1%), A. jandaei (n=4, 5.7%), A. media (n=2, 2.9%), and A. trota (n=1, 1.4%). The potential virulence of the present strains was estimated by performing PCR assays using the following seven virulence genes: cytotoxic enterotoxin (act), two cytotonic enterotoxins (alt and ast), glycerophospholipid:cholesterol acyltransferase (gcaT), DNase (exu), lipase (lip), and flagellin (fla). The detection rates of act, alt, ast, gcaT, exu, lip, and fla among all 70 strains were 91.4%, 55.7%, 27.1%, 97.1%, 95.7%, 100%, and 98.6%, respectively. In genotyping of enterotoxin genes, act(+)/alt(+)/ast(+), act(+)/alt(+)/ast(-), and act(+)/alt(-)/ast(-) genotypes were prevalent in A. hydrophila (8/12 strains), A. aquariorum (13/22 strains), and A. caviae (14/16 strains), respectively, suggesting a high heterogeneity among Aeromonas species. In this study, A. aquariorum, which has been an unrecorded species in Korea, can be an etiological agent for aeromoniasis of eel. PMID:23499189

  10. Extraction of Silver by Glucose.

    PubMed

    Baksi, Ananya; Gandi, Mounika; Chaudhari, Swathi; Bag, Soumabha; Gupta, Soujit Sen; Pradeep, Thalappil

    2016-06-27

    Unprecedented silver ion leaching, in the range of 0.7 ppm was seen when metallic silver was heated in water at 70 °C in presence of simple carbohydrates, such as glucose, making it a green method of silver extraction. Extraction was facilitated by the presence of anions, such as carbonate and phosphate. Studies confirm a two-step mechanism of silver release, first forming silver ions at the metal surface and later complexation of ionic silver with glucose; such complexes have been detected by mass spectrometry. Extraction leads to microscopic roughening of the surface making it Raman active with an enhancement factor of 5×10(8) . PMID:27119514

  11. Genetics Home Reference: Russell-Silver syndrome

    MedlinePlus

    ... Genetics Home Health Conditions Russell-Silver syndrome Russell-Silver syndrome Enable Javascript to view the expand/collapse ... Download PDF Open All Close All Description Russell-Silver syndrome is a growth disorder characterized by slow ...

  12. Silver Ink For Jet Printing

    NASA Technical Reports Server (NTRS)

    Vest, R. W.; Singaram, Saraswathi

    1989-01-01

    Metallo-organic ink containing silver (with some bismuth as adhesion agent) applied to printed-circuit boards and pyrolized in air to form electrically conductive patterns. Ink contains no particles of silver, does not have to be mixed during use to maintain homogeneity, and applied to boards by ink-jet printing heads. Consists of silver neodecanoate and bismuth 2-ethylhexanoate dissolved in xylene and/or toluene.

  13. Silver Nanoparticles in Dental Biomaterials

    PubMed Central

    Corrêa, Juliana Mattos; Mori, Matsuyoshi; Sanches, Heloísa Lajas; da Cruz, Adriana Dibo; Poiate, Isis Andréa Venturini Pola

    2015-01-01

    Silver has been used in medicine for centuries because of its antimicrobial properties. More recently, silver nanoparticles have been synthesized and incorporated into several biomaterials, since their small size provides great antimicrobial effect, at low filler level. Hence, these nanoparticles have been applied in dentistry, in order to prevent or reduce biofilm formation over dental materials surfaces. This review aims to discuss the current progress in this field, highlighting aspects regarding silver nanoparticles incorporation, such as antimicrobial potential, mechanical properties, cytotoxicity, and long-term effectiveness. We also emphasize the need for more studies to determine the optimal concentration of silver nanoparticle and its release over time. PMID:25667594

  14. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, G. M.; Vest, R. W.

    1984-01-01

    The development of flat plate solar arrays is reported. Photovoltaic cells require back side metallization and a collector grid system on the front surface. Metallo-organic decomposition (MOD) silver films can eliminate most of the present problems with silver conductors. The objectives are to: (1) identify and characterize suitable MO compounds; (2) develop generic synthesis procedures for the MO compounds; (3) develop generic fabrication procedures to screen printable MOD silver inks; (4) optimize processing conditions to produce grid patterns and photovoltaic cells; and (5) develop a model which describes the adhesion between the fired silver film and the silicon surface.

  15. Is the Atlantic surface temperature a good proxy for forecasting the recruitment of European eel in the Guadalquivir estuary?

    NASA Astrophysics Data System (ADS)

    Gutiérrez-Estrada, Juan Carlos; Pulido-Calvo, Inmaculada

    2015-01-01

    This study analysed the possibility of using the sea surface temperature (SST) of the Atlantic Ocean to predict the recruitment of European eels in one of the most important estuaries of the south of Europe. For this purpose, two different time series concerning glass eel in the Guadalquivir estuary (the first obtained from a set of fishery-independent experimental samplings in this estuary and the second from an unofficial database on commercial catches provided by one of the main local marketer-buyers) were standardised to obtain a single time series on a monthly scale. This series was correlated with a total of 368 SST time series for 368 sectors of 1.95° × 1.95° of the Atlantic Ocean covering the possible migration routes of adult eels and leptocephalous larvae. The significant sectors were clustered and selected as inputs for artificial neural network models (ANNs) with the objective of obtaining a model to forecast glass eel recruitment. Globally, the best result was given by an ANN with only 12 clusters as input variables and 35 neurons in the hidden layer. For this configuration, the explained variance in the test phase was slightly higher than 79%. These results were significantly better than those obtained with classical methods. The strong correlation between predicted and observed glass eel abundance suggests that: (a) there is a marked non-linear relationship between SST and glass eel recruitment in the Guadalquivir estuary; (b) SST is a good proxy for predicting glass eel recruitment and; (c) one of the main factors responsible for the changes in abundance of this species is changes in the ocean conditions.

  16. Natural hybrids in Atlantic eels (Anguilla anguilla, A. rostrata): evidence for successful reproduction and fluctuating abundance in space and time.

    PubMed

    Albert, Vicky; Jónsson, Bjarni; Bernatchez, Louis

    2006-06-01

    The outcome of natural hybridization is highly variable and depends on the nonexclusive effects of both pre- and post-mating reproductive barriers. The objective of this study was to address three specific questions regarding the dynamics of hybridization between the American and European eels (Anguilla rostrata and Anguilla anguilla). Using 373 AFLP loci, 1127 eels were genotyped, representing different life stages from both continents, as well as multiple Icelandic locations. We first evaluated the extent of hybridization and tested for the occurrence of hybrids beyond the first generation. Second, we tested whether hybrids were randomly distributed across continents and among Icelandic sampling sites. Third, we tested for a difference in the proportion of hybrids between glass eel and yellow eel stages in Iceland. Our results provided evidence for (i) an overall hybrid proportion of 15.5% in Iceland, with values ranging from 6.7% to 100% depending on life stages and locations; (ii) the existence of hybrids beyond the first generation; (iii) a nonrandom geographic distribution of hybrids in the North Atlantic; and (iv) a higher proportion of first and later generation hybrids in yellow eels compared to glass eels, as well as a significant latitudinal gradient in the proportion of hybrids in Icelandic freshwater. We propose that the combined effect of both differential survival of hybrids and variation in hybridization rate through time best explain these patterns. We discuss the possibility that climate change, which is impacting many environmental features in the North Atlantic, may have a determinant effect on the outcome of natural hybridization in Atlantic eels. PMID:16689906

  17. Imported Asian swamp eels (Synbranchidae: Monopterus) in North American live food markets: Potential vectors of non-native parasites

    USGS Publications Warehouse

    Nico, Leo G.; Sharp, Paul; Collins, Timothy M.

    2011-01-01

    Since the 1990s, possibly earlier, large numbers of Asian swamp eels (Synbranchidae: Monopterus spp.), some wild-caught, have been imported live from various countries in Asia and sold in ethnic food markets in cities throughout the USA and parts of Canada. Such markets are the likely introduction pathway of some, perhaps most, of the five known wild populations of Asian swamp eels present in the continental United States. This paper presents results of a pilot study intended to gather baseline data on the occurrence and abundance of internal macroparasites infecting swamp eels imported from Asia to North American retail food markets. These data are important in assessing the potential role that imported swamp eels may play as possible vectors of non-native parasites. Examination of the gastrointestinal tracts and associated tissues of 19 adult-sized swamp eels—identified as M. albus "Clade C"—imported from Vietnam and present in a U.S. retail food market revealed that 18 (95%) contained macroparasites. The 394 individual parasites recovered included a mix of nematodes, acanthocephalans, cestodes, digeneans, and pentastomes. The findings raise concern because of the likelihood that some parasites infecting market swamp eels imported from Asia are themselves Asian taxa, some possibly new to North America. The ecological risk is exacerbated because swamp eels sold in food markets are occasionally retained live by customers and a few reportedly released into the wild. For comparative purposes, M. albus "Clade C" swamp eels from a non-native population in Florida (USA) were also examined and most (84%) were found to be infected with internal macroparasites. The current level of analysis does not allow us to confirm whether these are non-native parasites.

  18. Swimbladder function and the spawning migration of the European eel Anguilla anguilla.

    PubMed

    Pelster, Bernd

    2014-01-01

    The spawning migration of the European eel is an extensive journey over 5000 to 7000 km from the European coast to the Sargasso Sea. Eels do not feed during this journey and on-board fuels must be sufficient to support the journey of 3.5 to 6 month, as well as sexual maturation and the spawning activity. Swimming of eels appears to be quite energy efficient compared to other fish species, and elevated hydrostatic pressure has been shown to even reduce the costs of transport. Recent studies revealed, however, that during traveling eels perform extensive diurnal migrations and swim at a depth of about 100-300 m at night time, but go down to 600-1000 m at day time. At a depth of 200 m eels are exposed to a hydrostatic pressure of 21 atmospheres (2.13 MPa), while at 800 m hydrostatic pressure increases to 81 atmospheres (8.21 MPa). Accordingly, without any compensation at a depth of 800 m swimbladder volume will be reduced to about 25% of the volume established with neutral buoyancy at 200 m. Consequently, these diurnal changes in depth must be taken into consideration for a calculation of the energy requirements of the spawning migration. Without compensation a compression of the swimbladder will result in a status of negative buoyancy, which makes swimming more costly. Trying to keep the status of neutral buoyancy during descent by gas secretion into the swimbladder in turn requires metabolic activity to enhance swimbladder perfusion and for acid production of the gas gland cells to stimulate gas secretion. During ascent gas is passively removed from the swimbladder in the resorbing section and in the blood transported to the gills, where it is lost into the water. Accordingly, the swimbladder appears to be a crucial organ for the spawning migration. It can be assumed that an impairment of swimbladder function for example due to an infection with the nematode Anguillicola crassus significantly threatens the success of the spawning migration. PMID:25646080

  19. Swimbladder function and the spawning migration of the European eel Anguilla anguilla

    PubMed Central

    Pelster, Bernd

    2014-01-01

    The spawning migration of the European eel is an extensive journey over 5000 to 7000 km from the European coast to the Sargasso Sea. Eels do not feed during this journey and on-board fuels must be sufficient to support the journey of 3.5 to 6 month, as well as sexual maturation and the spawning activity. Swimming of eels appears to be quite energy efficient compared to other fish species, and elevated hydrostatic pressure has been shown to even reduce the costs of transport. Recent studies revealed, however, that during traveling eels perform extensive diurnal migrations and swim at a depth of about 100–300 m at night time, but go down to 600–1000 m at day time. At a depth of 200 m eels are exposed to a hydrostatic pressure of 21 atmospheres (2.13 MPa), while at 800 m hydrostatic pressure increases to 81 atmospheres (8.21 MPa). Accordingly, without any compensation at a depth of 800 m swimbladder volume will be reduced to about 25% of the volume established with neutral buoyancy at 200 m. Consequently, these diurnal changes in depth must be taken into consideration for a calculation of the energy requirements of the spawning migration. Without compensation a compression of the swimbladder will result in a status of negative buoyancy, which makes swimming more costly. Trying to keep the status of neutral buoyancy during descent by gas secretion into the swimbladder in turn requires metabolic activity to enhance swimbladder perfusion and for acid production of the gas gland cells to stimulate gas secretion. During ascent gas is passively removed from the swimbladder in the resorbing section and in the blood transported to the gills, where it is lost into the water. Accordingly, the swimbladder appears to be a crucial organ for the spawning migration. It can be assumed that an impairment of swimbladder function for example due to an infection with the nematode Anguillicola crassus significantly threatens the success of the spawning migration. PMID:25646080

  20. Female sexuality

    PubMed Central

    Rao, T.S. Sathyanarana; Nagaraj, Anil Kumar M.

    2015-01-01

    Sex is a motive force bringing a man and a woman into intimate contact. Sexuality is a central aspect of being human throughout life and encompasses sex, gender identities and roles, sexual orientation, eroticism, pleasure, intimacy, and reproduction. Sexuality is experienced and expressed in thoughts, fantasies, desires, beliefs, attitudes, values, behaviors, practices, roles and relationships. Though generally, women are sexually active during adolescence, they reach their peak orgasmic frequency in their 30 s, and have a constant level of sexual capacity up to the age of 55 with little evidence that aging affects it in later life. Desire, arousal, and orgasm are the three principle stages of the sexual response cycle. Each stage is associated with unique physiological changes. Females are commonly affected by various disorders in relation to this sexual response cycle. The prevalence is generally as high as 35–40%. There are a wide range of etiological factors like age, relationship with a partner, psychiatric and medical disorders, psychotropic and other medication. Counseling to overcome stigma and enhance awareness on sexuality is an essential step in management. There are several effective psychological and pharmacological therapeutic approaches to treat female sexual disorders. This article is a review of female sexuality. PMID:26330647

  1. Female sexuality.

    PubMed

    Rao, T S Sathyanarana; Nagaraj, Anil Kumar M

    2015-07-01

    Sex is a motive force bringing a man and a woman into intimate contact. Sexuality is a central aspect of being human throughout life and encompasses sex, gender identities and roles, sexual orientation, eroticism, pleasure, intimacy, and reproduction. Sexuality is experienced and expressed in thoughts, fantasies, desires, beliefs, attitudes, values, behaviors, practices, roles and relationships. Though generally, women are sexually active during adolescence, they reach their peak orgasmic frequency in their 30 s, and have a constant level of sexual capacity up to the age of 55 with little evidence that aging affects it in later life. Desire, arousal, and orgasm are the three principle stages of the sexual response cycle. Each stage is associated with unique physiological changes. Females are commonly affected by various disorders in relation to this sexual response cycle. The prevalence is generally as high as 35-40%. There are a wide range of etiological factors like age, relationship with a partner, psychiatric and medical disorders, psychotropic and other medication. Counseling to overcome stigma and enhance awareness on sexuality is an essential step in management. There are several effective psychological and pharmacological therapeutic approaches to treat female sexual disorders. This article is a review of female sexuality. PMID:26330647

  2. Landslide Sediment Production in the Middle Fork Eel River: 1940-2002

    NASA Astrophysics Data System (ADS)

    de La Fuente, J. A.; Snavely, W. P.; Miller, A. R.; Elder, D.

    2003-12-01

    A sequential air photo analysis was conducted by the U.S. Forest Service (USFS) and North State Resources in the 753 square mile Middle Fork Eel River basin, under contract to US Environmental Protection Agency as part of a Total Maximum Daily Load (TMDL) assessment. All landslides visible on air photos which appeared to deliver sediment to the stream system were mapped, and the delivered volume estimated. Landslides on undisturbed hillslopes were classified as natural, those within recently burned areas as fire-related, those in harvest units as harvest-related, and those adjacent to roads as road-related. About 5% of the landslides were field verified. Data were then summed for three air photo intervals, spanning the period 1940-2002. A total of 4,122 landslides were inventoried, delivering a total of 24,969,836 cubic yards of sediment to the stream system, and occupying 13,526 acres. The photo interval 1940-1969 accounted for 79% of the delivered volume, 1970-1984 for 8%, and 1985-2002 for 13%. This pattern is similar to that observed in many NW California watersheds where the storms of 1955 and 1964 generated large volumes of landslide sediment. Landslide volume per unit area delivered to streams from 1940-2002 averaged 0.84 cubic yards/acre/year for the Middle Fork Eel, and was highest in the Black Butte River, and Williams-Thatcher subwatersheds which exhibited rates of 1.55 and 1.31 cubic yards/acre/year respectively. The lowest delivery rates were in Upper Middle Fork (0.29), and Round Valley (0.44). Natural landslides accounted for 89.9% of the total, fire-related for 1.9%, harvest-related for 0.4%, road-related for 3.4%, and undetermined 4.4%. A large proportion of the total delivered sediment originated from the toes of large deep seated landslides adjacent to streams. Many of these landslides exhibited multiple years of activity, shedding debris slides of varying sizes at different times. The mapped active landslides are concentrated near streams, but

  3. Female Reproductive System

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Female Reproductive System KidsHealth > For Teens > Female Reproductive System Print A ... and female reproductive systems. continue What Is the Female Reproductive System? Most species have two sexes: male and female. ...

  4. Synergistic and singular effects of river discharge and lunar illumination on dam passage of upstream migrant yellow-phase American eels

    USGS Publications Warehouse

    Welsh, Stuart; Aldinger, Joni L.; Braham, Melissa; Zimmerman, Jennifer L.

    2016-01-01

    Monitoring of dam passage can be useful for management and conservation assessments of American eel, particularly if passage counts can be examined over multiple years. During a 7-year study (2007–2013) of upstream migration of American eels within the lower Shenandoah River (Potomac River drainage), we counted and measured American eels at the Millville Dam eel pass, where annual study periods were determined by the timing of the eel pass installation during spring or summer and removal during fall. Daily American eel counts were analysed with negative binomial regression models, with and without a year (YR) effect, and with the following time-varying environmental covariates: river discharge of the Shenandoah River at Millville (RDM) and of the Potomac River at Point of Rocks, lunar illumination (LI), water temperature, and cloud cover. A total of 17 161 yellow-phase American eels used the pass during the seven annual periods, and length measurements were obtained from 9213 individuals (mean = 294 mm TL, s.e. = 0.49, range 183–594 mm). Data on passage counts of American eels supported an additive-effects model (YR + LI + RDM) where parameter estimates were positive for river discharge (β = 7.3, s.e. = 0.01) and negative for LI (β = −1.9, s.e. = 0.34). Interestingly, RDM and LI acted synergistically and singularly as correlates of upstream migration of American eels, but the highest daily counts and multiple-day passage events were associated with increased RDM. Annual installation of the eel pass during late spring or summer prevented an early spring assessment, a period with higher RDM relative to those values obtained during sampling periods. Because increases in river discharge are climatically controlled events, upstream migration events of American eels within the Potomac River drainage are likely linked to the influence of climate variability on flow regime.

  5. Molecular physiology and functional morphology of SO₄²⁻ excretion by the kidney of seawater-adapted eels.

    PubMed

    Watanabe, Taro; Takei, Yoshio

    2011-05-15

    Marine teleosts actively excrete SO₄²⁻ and keep the plasma concentration of this ion much lower than that of environmental seawater (SW). We used the eel as a model to study the excretory mechanism of SO₄²⁻ because this euryhaline species changes SO₄²⁻ regulation drastically after transfer from freshwater (FW) to SW. Time-course studies showed that plasma SO₄²⁻ concentration decreased 3 days after transfer of eels from FW to SW, while urine SO₄²⁻ concentration increased on 1 day. Detailed analyses showed that urine SO₄²⁻ concentration increased linearly from 6 h after SW transfer; however, this did not immediately translate to increased SO₄²⁻ excretion because the volume of urine was decreased. We identified five SO₄²⁻ transporters in the eel kidney. Three of these (Slc26a1, Slc26a6b and Slc26a6c) are expressed in both SW- and FW-acclimated eels while Slc26a6a and Slc13a1 are expressed in SW-acclimated eels and FW-acclimated eels, respectively. We showed that changes in Slc26a6a and Slc13a1 gene expression occurred 1-3 days after SW transfer. In SW eel kidneys, immunohistochemistry using specific antisera against each transporter protein showed that Slc26a6a and Slc26a6c are localized on the apical membrane of the P1 segment of the proximal tubule, while Slc26a6b is localized on the apical membrane and Slc26a1 on the basolateral membrane of the P2 segment. The current study revealed complex molecular mechanisms of SO₄²⁻ excretion in the SW eel kidney that involve segment-specific localization of multiple Slc transporters in proximal tubules and modulation of their expression in different SO₄²⁻ environments. This precise regulatory mechanism may endow the eel with euryhalinity. PMID:21525326

  6. Construction of a BAC library and identification of Dmrt1 gene of the rice field eel, Monopterus albus

    SciTech Connect

    Jang Songhun; Zhou Fang; Xia Laixin; Zhao Wei; Cheng Hanhua . E-mail: hhcheng@whu.edu.cn; Zhou Rongjia . E-mail: rjzhou@whu.edu.cn

    2006-09-22

    A bacterial artificial chromosome (BAC) library was constructed using nuclear DNA from the rice field eel (Monopterus albus). The BAC library consists of a total of 33,000 clones with an average insert size of 115 kb. Based on the rice field eel haploid genome size of 600 Mb, the BAC library is estimated to contain approximately 6.3 genome equivalents and represents 99.8% of the genome of the rice field eel. This is first BAC library constructed from this species. To estimate the possibility of isolating a specific clone, high-density colony hybridization-based library screening was performed using Dmrt1 cDNA of the rice field eel as a probe. Both library screening and PCR identification results revealed three positive BAC clones which were overlapped, and formed a contig covering the Dmrt1 gene of 195 kb. By sequence comparisons with the Dmrt1 cDNA and sequencing of first four intron-exon junctions, Dmrt1 gene of the rice field eel was predicted to contain four introns and five exons. The sizes of first and second intron are 1.5 and 2.6 kb, respectively, and the sizes of last two introns were predicted to be about 20 kb. The Dmrt1 gene structure was conserved in evolution. These results also indicate that the BAC library is a useful resource for BAC contig construction and molecular isolation of functional genes.

  7. Corrosion protection for silver reflectors

    DOEpatents

    Arendt, Paul N.; Scott, Marion L.

    1991-12-31

    A method of protecting silver reflectors from damage caused by contact with gaseous substances which are often present in the atmosphere and a silver reflector which is so protected. The inventive method comprises at least partially coating a reflector with a metal oxide such as aluminum oxide to a thickness of 15 .ANG. or less.

  8. Nanoindentation studies on silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Saha, Dhriti Ranjan; Mandal, Amrita; Mitra, Sreemanta; Mada, Mykanth Reddy; Boughton, Philip; Bandyopadhyay, Sri; Chakravorty, Dipankar

    2013-06-01

    Nanodimensional metallic silver was grown by electrodeposion technique in a semi solid polymer matrix of polyacrylamide. The whole structure looks like dendronic. The average particle diameter of the as grown metallic silver is 13 nm. Nanoindentation study of these nanoparticles shows modulus and hardness value as 103.93 GPa and 3.12 GPa respectively.

  9. Identification of Silver and Palladium in Irradiated TRISO Coated Particles of the AGR-1 Experiment

    SciTech Connect

    van Rooyen, Y. J.; Lillo, T. M.; Wu, Y. Q.

    2014-03-01

    Evidence of the release of certain metallic fission product through intact tristructural isotropic (TRISO) particles has been seen for decades around the world, as well as in the recent AGR-1 experiment at Idaho National Laboratory (INL). However, understanding the basic mechanism of transport is still lacking. This understanding is important because the TRISO coating is part of the high temperature gas reactor functional containment and critical for the safety strategy for licensing purposes. Our approach to identify fission products in irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), Electron Energy Loss Spectroscopy (EELS) and Energy Filtered TEM (EFTEM), has led to first-of-a-kind data at the nano-scale indicating the presence of silver at triple points and grain boundaries of the SiC layer in the TRISO particle. Cadmium was also found in the triple junctions. In this initial study, the silver was only identified in SiC grain boundaries and triple points on the edge of the SiC-IPyC interface up to a depth of approximately 0.5 um. Palladium was identified as the main constituent of micron-sized precipitates present at the SiC grain boundaries. Additionally spherical nano-sized palladium rich precipitates were found inside the SiC grains. These nano-sized Pd precipitates were distributed up to a depth of 5 um away from the SiC-IPyC interlayer. No silver was found in the center of the micron-sized fission product precipitates using these techniques, although silver was found on the outer edge of one of the Pd-U-Si containing precipitates which was facing the IPyC layer. Only Pd-U containing precipitates were identified in the IPyC layer and no silver was identified in the IPyC layer. The identification of silver alongside the grain boundaries and the findings of Pd alongside grain boundaries as well as inside the grains, provide significant knowledge for understanding silver and palladium transport in TIRSO fuel, which has been

  10. Tidal-Flat Macrobenthos as Diets of the Japanese Eel Anguilla japonica in Western Japan, with a Note on the Occurrence of a Parasitic Nematode Heliconema anguillae in Eel Stomachs.

    PubMed

    Kan, Kotaro; Sato, Masanori; Nagasawa, Kazuya

    2016-02-01

    Dietary items of the Japanese eel Anguilla japonica inhabiting estuaries were examined by analyses of the gut (stomach and intestine) contents in two areas in Kyushu, western Japan. In a small estuary in Kagoshima Bay, where seven eel guts were examined, almost all of the dietary organisms consisted of Hemigrapsus crabs and Hediste polychaetes, both of which commonly occurred on tidal flats of this site during our survey on the macrobenthic fauna. In another large estuary in the innermost part of the Ariake Sea, where 14 eel guts were examined, 11 macrobenthic species (nine crustaceans, a polychaete, and a gastropod) were found in the gut contents, mostly consisting of mudflat-specific species. The dietary items are almost completely different not only between the two estuaries, but also among three neighboring sites within the large estuary in the Ariake Sea. These results show that Japanese eels feed on various macrobenthic invertebrates inhabiting estuarine tidal flats at each site. The variety of the prey species occupying different habitats indicates that their foraging areas extend to a wide range of estuarine tidal flats from the upper to lower littoral zones. The physalopterid nematode Heliconema anguillae was found parasitic in eel stomachs in both estuaries. The prevalence of the nematode was higher in the estuary in Kagoshima Bay (100%) than that in the Ariake Sea (43%), although the intensity in the former (4-94 nematodes per infected stomach) was comparable to that of the latter (2-96). The relationship between the nematode infection and the dietary items of Japanese eels is discussed. PMID:26853869

  11. Effects of selection for behavior, human approach mode and sex on vocalization in silver fox

    PubMed Central

    Gogoleva, Svetlana S.; Volodina, Elena V.; Kharlamova, Anastasia V.; Trut, Lyudmila N.

    2013-01-01

    This study presents a first direct comparison of vocal type, call rate and time spent vocalizing among Unselected, Tame and Aggressive strains of silver fox (Vulpes vulpes) in three modes of human approach (Provoking, Approach–Retreat, and Static). Also, it provides a first comparison of male and female vocal output in the Provoking test. Vocal types were found strain-specific irrespective of the fox sex or the test. Males had higher call rates and spent shorter times vocalizing than females. These results support the evidence of genetic-based emotional states, triggering vocal behavior in silver fox strains, and suggest sex dimorphism in vocal activity toward humans. PMID:23525128

  12. Heavy metal contamination of European eel (Anguilla anguilla) and brown trout (Salmo trutta) caught in wild ecosystems in Spain.

    PubMed

    Linde, A R; Sanchez-Galan, S; Garcia-Vazquez, E

    2004-10-01

    In this study we analyzed the pattern of copper (Cu), cadmium (Cd), lead (Pb), and mercury (Hg) accumulation in liver (as a detoxifying organ) and muscle (as the most important tissue for human consumption) of brown trout (Salmo trutta) and European eel (Anguilla anguilla) caught in two wild Spanish rivers where both species are usually angled for human consumption. Cd, Pb, and Cu accumulated preferentially in the liver of both species. Hg accumulated both in the liver and muscle in brown trout, whereas it accumulated preferentially in muscle in European eel. Both high metal content and preferential accumulation of Hg in muscle suggest that European eel is more harmful than brown trout for human consumption. PMID:15508654

  13. Influence of nematode Anguillicoloides crassus infestation on the cellular and humoral innate immunity in European eel (Anguilla anguilla L.)

    PubMed Central

    Terech-Majewska, Elżbieta; Siwicki, Andrzej K.

    2015-01-01

    Parasitic invasions are recognized as one of the primary factors responsible for decreasing populations of European eel. The aim of the present study was to determine the influence of infestation with the nematode Anguillicoloides crassus on the innate immunity in European eel (Anguilla anguilla). Anguillicoloides crassus parasitizes the swim bladder of this fish. Levels of the following immunological parameters were measured: spleen phagocyte respiratory burst activity, spleen phagocyte potential killing activity, pronephros lymphocyte proliferation stimulated by concanavaline A or lipopolisaccharide, plasma lysozyme and ceruloplasmin activity, total protein and immunoglobulin (Ig) serum levels. The analyses of the results of humoral and cellular immunity indicate that all studied parameters were statistically significant higher (p < 0.05) in non-infested fish compared to the ones with anguillicolosis except for ceruloplasmin level. These data suggest that the A. crassus infestation in European eel is responsible for a decreased immune response what could result in higher susceptibility to other pathogenic conditions. PMID:26557024

  14. Ecological study of the migration of eel by synchrotron radiation induced X ray fluorescence imaging of otoliths

    NASA Astrophysics Data System (ADS)

    Nakai, Izumi; Iwata, Raita; Tsukamoto, Katsumi

    1999-01-01

    Synchrotron radiation-induced X-ray fluorescence imaging is suitable for determining the distribution of trace elements in fish otoliths. The Sr/Ca ratio in an otolith is an indicator of salinity changes and can be used to clarify the migration history of the eel, a catadromous fish. The otoliths of eel collected from the Tone and Elbe rivers exhibited a typical catadromous pattern, i.e. birth and breeding occurred in the ocean, but the remainder of their lives was spent in fresh water. In contrast, eels from the East China Sea and North Sea exhibited an unusual sea-locking phenomenon, as they appear to have remained in marine habitats throughout their lives.

  15. Silver clusters and chemistry in zeolites

    SciTech Connect

    Sun, T.; Seff, K. . Dept. of Chemistry)

    1994-06-01

    The spectroscopic work done on silver clusters trapped in solid noble gas matrices at low temperature has been extensively reviewed by Ozin, and Henglein has done the same for photochemical studies of colloidal silver particles in solution. This article will review the chemistry of silver in zeolite hosts, including the synthesis and structures of silver clusters. 127 refs.

  16. Rethinking Schools and the Power of Silver

    ERIC Educational Resources Information Center

    Sleeter, Christine

    2011-01-01

    This 25th anniversary of "Rethinking Schools" can be thought of as its silver anniversary. Silver itself must be considered through contrasting lenses. On the one hand, as lessons in "Rethinking Globalization" teach, silver and gold were the basis of Europe's horrendous exploitation of Latin America. On the other hand, silver is often associated…

  17. Acute inhalation toxicity of silver nanoparticles.

    PubMed

    Sung, Jae Hyuck; Ji, Jun Ho; Song, Kyung Seuk; Lee, Ji Hyun; Choi, Kyung Hee; Lee, Sang Hee; Yu, Il Je

    2011-03-01

    The acute inhalation toxicity of silver nanoparticles was studied in Sprague-Dawley rats. Seven-week-old rats, weighing approximately 218 g (males) and 153 g (females), were divided into four groups (five rats in each group): fresh-air control, low-dose (0.94 × 10(6) particle/cm(3), 76 µg/m(3)), middle-dose (1.64 × 10(6) particle/ cm(3), 135 µg/m( 3)), and high-dose (3.08 × 10(6) particle/cm(3), 750 µg/m(3)). The animals were then exposed to silver nanoparticles (average diameter 18-20 nm) for 4 hours in a whole-body inhalation chamber. The experiment was conducted following Organization Economic Cooperation and Development (OECD) test guideline 403 with the application of good laboratory practice (GLP). In addition to mortality and clinical observations, the body weights, food consumption, and pulmonary function tests were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, and the organ weights measured. The lung function was also measured twice per week after the initial 4-hour exposure. No significant body weight changes or clinical changes were found during the 2-week observation period. The lung function tests also indicated no significant difference between the fresh air control and the exposed groups. Thus, LC50 silver nanoparticles are suggested for higher than 3.1 × 10(6) particles/cm(3) (750 µg/m(3)). PMID:20870693

  18. Thermal stability of PLD grown silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Shokeen, Poonam; Jain, Amit; Kapoor, Avinashi

    2016-05-01

    Present work discusses the stability of silver nanoparticles at different annealing temperatures. Air muffle furnace annealing is performed to study the thermal stability of pulsed laser deposited silver nanoparticles. Silver reacts with atmospheric oxygen to form silver oxide at annealing temperatures below 473K and thermal decomposition of silver oxide takes place at temperatures above 473K. Oxide formation results in core shrinkage of silver, which in turn affects the surface plasmon resonance of silver nanoparticles. With increase in annealing temperature, the surface plasmon effect of nanoparticles starts to fade. SEM, XRD and UV-vis spectroscopy have been performed to analysis various structural and optical properties.

  19. Acute regulation of glucose uptake in cardiac muscle of the American eel Anguilla rostrata.

    PubMed

    Rodnick; Bailey; West; Driedzic

    1997-01-01

    We investigated the effects of anoxia and contractile activity on glucose uptake and the intracellular location of hexokinase in cardiac muscle of the American eel Anguilla rostrata. Uptake of 2-deoxyglucose (2-DG) by ventricle strips at 15 °C was increased by 45 % by anoxia and by 85 % by contractile activity over basal conditions. The anoxia- and contraction-induced increase in basal 2-DG uptake was inhibited completely by 25 µmol l-1 cytochalasin B, suggesting that facilitated glucose transporters are involved. Maximal activity of hexokinase in whole homogenates (approximately 10 µmol min-1 g-1 tissue) was 200 times higher than the maximal rate of 2-DG uptake measured in vitro (46 nmol min-1 g-1 tissue). Only 20­25 % of hexokinase activity was localized to the mitochondrial fraction, and this was not altered by perfusion of the hearts with anoxic media. It is therefore unlikely that anoxia-induced stimulation of 2-DG uptake is mediated by intracellular translocation of hexokinase. As in the case of mammalian muscle, glucose 6-phosphate is a potent inhibitor of hexokinase in eel cardiac muscle (IC50=0.44 mmol l-1). In summary, anoxia and contractile activity significantly increase 2-DG uptake in cardiac muscle of American eels, and glucose transport may be rate-limiting for glucose utilization. Increased utilization of glucose during anoxia or contractile activity may involve the recruitment of facilitative glucose transport proteins to the cell surface of myocytes or an increase in the intrinsic activity of glucose transporters already residing at the cell surface. PMID:9344975

  20. Acoustic backscatter of the 1995 flood deposit on the Eel shelf

    USGS Publications Warehouse

    Borgeld, J.C.; Hughes-Clarke, John E.; Goff, John A.; Mayer, Larry A.; Curtis, Jennifer A.

    1999-01-01

    Acoustic swath mapping and sediment box coring conducted on the continental shelf near the mouth of the Eel River revealed regional variations in acoustic backscatter that can be related to the shelf sedimentology. The acoustic-backscatter variations observed on the shelf were unusually narrow compared to the response of similar sediment types documented in other areas. However, the acoustic data revealed four principal bottom types on the shelf that can be related to sedimentologic differences observed in cores. The four areas are: (1) low acoustic backscatter associated with the nearshore-sand facies and the prodelta terraces of the Eel and Mad rivers, composed of fine sands and coarse silts with low porosity; (2) high acoustic backscatter associated with fine silts characterized by high porosity and deposited by the 1995 flood of the Eel River; (3) intermediate acoustic backscatter in the outer-shelf muds, where clayey silts are accumulating and the 1995 flood apparently had limited direct effect; and (4) intermediate acoustic backscatter near the fringes of the 1995 flood deposits and in areas where the flood sediments were more disrupted by post-depositional processes. The highest acoustic backscatter was identified in areas where the 1995 flood sediments remained relatively intact and near the shelf surface into the summer of 1995. Cores collected from these areas contained wavy or lenticular bedding. The rapid deposition of the high-porosity muddy layers results in better preservation of incorporated ripple forms than in areas less directly impacted by the flood deposit. The high-porosity muddy layers allow acoustic penetration into the sediments and result in greater acoustic backscatter from incorporated roughness elements.

  1. Giant Scour on Eel Fan, California Records Decadal Trubidite Recurrence Interval

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; McGann, M.; Edwards, B. D.; Barnes, P.; Gwiazda, R.; Lundsten, E. M.; Anderson, K.; Sumner, E.; Caress, D. W.

    2013-12-01

    Analysis of an exceptional exposure of thinly bedded turbidites in the headwall of a giant submarine scour on Eel Submarine Fan reveals that turbidites were being emplaced with a remarkably high frequency during the late Pleistocene to early Holocene. ROV observations, vibracores and push cores show an 87 m thick outcrop of fine-grained turbidites that are between 3 and 40 cm thick. The turbidites are composed of fining-upwards cycles grading from fine or very fine sand through to silty-mud. Within turbidites reversals in grain size occur representing fluctuating flow conditions. An abundance of woody material and shallow dwelling foraminifera within the turbidites demonstrates the flows originated in shallow water. The silty-mud horizons are barren of pelagic foraminifera, suggesting that they are the late stages of turbidites and that intervening hemipelagic material is absent. Twenty-one 14C measurements made on the transported shallow-water foraminifera and wood fragments within eighteen push cores taken from the scarp reveal that the entire 87 m section was deposited 6 to 14 thousand years BP. Shipboard video observations indicate the appearance of the scarp face is similar throughout the exposed face. In a 10 m section with excellent video, 88 turbidites were counted. Assuming that the entire 87 m face comprises the same rhythmic alterations, more than 766 turbidites were deposited during this ~8,000 year interval. This requires a decadal turbidite recurrence interval. As these deposits are downstream of the Eel River, these data have intriguing implications about the enhanced impact of the Eel River during the late Pleistocene and early Holocene.

  2. Plasma biochemistry values of recently wild-caught purple mouth moray eels (Gymnothorax vicinus).

    PubMed

    Erlacher-Reid, Claire; Hoffman, Walter E; Priede, Megan; Pulver, Robert; Tuttle, Allison D

    2011-12-01

    The primary purpose of this study was to establish plasma biochemistry parameters for healthy recently wild-caught purple mouth moray eels (Gymnothorax vicinus) to provide a baseline of data for improved medical care in an aquarium or zoologic setting and for wild health assessments. Thirty-one clinically healthy purple mouth moray eels of unknown age and sex were caught from the wild, and were anesthetized 50 days following capture for blood collection from the ventral coccygeal vein. The median plasma biochemistry values were as follows: hematocrit = 21%, creatinine kinase = 2,100 U/L, lactate dehydrogenase = 97 U/L, aspartate aminotransferase = 88 U/L, alanine aminotransferase = 51 U/L, alkaline phosphatase 3,939 U/L, gamma-glutamyl transpeptidase = 1 U/L, amylase = 40 U/L, blood urea nitrogen = < 11 mg/dl, glucose = 21 mg/dl, calcium = 12.5 mg/dl, triglyceride = 206 mg/dl, creatinine = 0.1 mg/dl, cholesterol = 334 mg/dl, total bilirubin = < 0.1 mg/dl, phosphorus = 6.5 mg/dl, total protein = 4.2 g/dl, albumin = 1.5 g/dl, globulin = 2.7 g/dl, albumin/ globulin ratio = 0.6, sodium = 185 mmol/L, potassium = 3.7 mmol/L, and chloride = 175 mmol/L. Alkaline phosphatase isoenzyme results indicate that the majority of the plasma alkaline phosphatase is the liver isoenzyme. The data acquired in this study also provide baseline values for cholesterol and triglycerides in recently wild-caught moray eels to aid in monitoring elevations to these values in an aquarium setting over time so adjustments to the dietary regime may be utilized to prevent or improve conditions such as lipid keratopathy. PMID:22204062

  3. Does asymmetric gene flow among matrilines maintain the evolutionary potential of the European eel?

    PubMed

    Baltazar-Soares, Miguel; Eizaguirre, Christophe

    2016-08-01

    Using evolutionary theory to predict the dynamics of populations is one of the aims of evolutionary conservation. In endangered species, with geographic range extending over continuous areas, the predictive capacity of evolutionary-based conservation measures greatly depends on the accurate identification of reproductive units. The endangered European eel (Anguilla anguilla) is a highly migratory fish species with declining population due to a steep recruitment collapse in the beginning of the 1980s. Despite punctual observations of genetic structure, the population is viewed as a single panmictic reproductive unit. To understand the possible origin of the detected structure in this species, we used a combination of mitochondrial and nuclear loci to indirectly evaluate the possible existence of cryptic demes. For that, 403 glass eels from three successive cohorts arriving at a single location were screened for phenotypic and genetic diversity, while controlling for possible geographic variation. Over the 3 years of sampling, we consistently identified three major matrilines which we hypothesized to represent demes. Interestingly, not only we found that population genetic models support the existence of those matriline-driven demes over a completely panmictic mode of reproduction, but also we found evidence for asymmetric gene flow amongst those demes. We uphold the suggestion that the detection of demes related to those matrilines reflect a fragmented spawning ground, a conceptually plausible consequence of the low abundance that the European eel has been experiencing for three decades. Furthermore, we suggest that this cryptic organization may contribute to the maintenance of the adaptive potential of the species. PMID:27551384

  4. Evaluation of methods to determine sperm density for the European eel, Anguilla anguilla.

    PubMed

    Sørensen, S R; Gallego, V; Pérez, L; Butts, I A E; Tomkiewicz, J; Asturiano, J F

    2013-12-01

    European eel, Anguilla anguilla, is a target species for future captive breeding, yet best methodology to estimate sperm density for application in in vitro fertilization is not established. Thus, our objectives were to evaluate methods to estimate European eel sperm density including spermatocrit, computer-assisted sperm analysis (CASA) and flow cytometry (FCM), using Neubauer Improved haemocytometer as benchmark. Initially, relationships between spermatocrit, haemocytometer counts and sperm motility were analysed, as well as the effect of sperm dilution on haemocytometer counts. Furthermore, accuracy and precision of spermatocrit, applying a range of G-forces, were tested and the best G-force used in method comparisons. We found no effect of dilution on haemocytometer sperm density estimates, whereas motility associated positively with haemocytometer counts, but not with spermatocrit. Results from all techniques, spermatocrit, CASA and FCM, showed significant positive correlations with haemocytometer counts. The best correlation between spermatocrit and haemocytometer counts was obtained at 6000 × g (r = 0.68). Of two CASA variants, one or three photographic fields (CASA-1 and CASA-2), CASA-2 showed a very high accuracy to haemocytometer counts (r = 0.93), but low precision (CV: CASA-2 = 28.4%). FCM was tested with and without microfluorospheres (FCM-1 and FCM-2), and relationships to haemocytometer counts were highly accurate (FCM-1: r = 0.94; FCM-2: r = 0.88) and precise (CV: FCM-1 = 2.5; FCM-2 = 2.7%). Overall, CASA-2 and FCM-1 feature reliable methods for quantification of European eel sperm, but FCM-1 has a clear advantage featuring highest precision and accuracy. Together, these results provide a useful basis for gamete management in fertilization protocols. PMID:23772654

  5. Energy reserves mobilization in the yellow eel as herbicide exposure effect.

    PubMed

    Fernández-Vega, C; Sancho, E; Ferrando, M D

    2015-09-01

    Thiobencarb and propanil are two of the most extensive used herbicides worldwide in rice cultivation. Especially scanty is the available information regarding the effect of herbicides on fish energy resources. In the present study, the effect of sublethal exposure to these herbicides on the energy reserves of juvenile eel Anguilla anguilla was compared. Eels were exposed to 72 h to the herbicide thiobencarb (0.22 mg L(-1)) or Propanil (0.63 mg L(-1)), and allowed to recover in clean water (144 h). Caloric content was determined in liver and skeletal muscle. Fish exposed to thiobencarb rapidly mobilized energy. Reserves from liver were depleted (21%) compared to control values (2.50 kcal g(-1)) at 2 h, whereas in muscle diminished between 12 and 72 h (35%) (control value 0.89 kcal g(-1)). Energy reserves from liver normalized after 144 h in water while in the skeletal muscle were still depleted (24%). Major harmful effects were induced by propanil. Caloric content in liver diminished from the first hours (depletion of 70% at 48h exposure) and in skeletal muscle a 60% (72 h). At the end of the recovery period, energy reserves in pre-exposed eels represented less than 50% compared to control animals. The study indicated that thiobencarb and propanil would constitute a great risk to animals inhabiting freshwater bodies nearby fields of application. Judging from the results, herbicides resulted toxic enough to mobilize fish energy stores. On the other hand, a period of six days in herbicide-free water was not enough time to allow fish to restore energy budgets. PMID:25917606

  6. Larval Gnathostoma spinigerum Detected in Asian Swamp Eels, Monopterus albus, Purchased from a Local Market in Yangon, Myanmar.

    PubMed

    Chai, Jong-Yil; Sohn, Woon-Mok; Na, Byoung-Kuk; Park, Jong-Bok; Jeoung, Hoo-Gn; Hoang, Eui-Hyug; Htoon, Thi Thi; Tin, Htay Htay

    2015-10-01

    The present study was performed to determine the infection status of swamp eels with Gnathostoma sp. larvae in Myanmar. We purchased total 37 Asian swamp eels, Monopterus albus, from a local market in Yangon in June and December 2013 and 2014. All collected eels were transferred with ice to our laboratory and each of them was examined by the artificial digestion technique. A total of 401 larval gnathostomes (1-96 larvae/eel) were detected in 33 (89.2%) swamp eels. Most of the larvae (n=383; 95.5%) were found in the muscle. The remaining 18 larvae were detected in the viscera. The advanced third-stage larvae (AdL3) were 2.3-4.4 mm long and 0.25-0.425 mm wide. The characteristic head bulb (0.093 × 0.221 mm in average size) with 4 rows of hooklets, muscular long esophagus (1.025 mm), and 2 pairs of cervical sacs (0.574 mm) were observed by light microscopy. The average number of hooklets in the 1st, 2nd, 3rd, and 4th rows was 41, 45, 48, and 51, respectively. As scanning electron microscopic findings, the characteristic 4-5 rows of hooklets on the head bulb, a cervical papilla, tegumental spines regularly arranged in the transverse striations, and an anus were well observed. Based on these morphological characters, they were identified as the AdL3 of Gnathostoma spinigerum. By the present study, it has been confirmed for the first time that Asian swamp eels, M. albus, from Yangon, Myanmar are heavily infected with G. spinigerum larvae. PMID:26537042

  7. Invasive swimbladder parasite Anguillicoloides crassus: infection status 15 years after discovery in wild populations of American eel Anguilla rostrata.

    PubMed

    Hein, Jennifer L; Arnott, Stephen A; Roumillat, William A; Allen, Dennis M; de Buron, Isaure

    2014-01-16

    A year-round survey of American eels Anguilla rostrata was performed at 5 localities in South Carolina (SC), USA, 15 yr after the first infection by the nematode Anguillicoloides crassus was reported from Winyah Bay, SC. Infections by adult stages of A. crassus in the swimbladder lumen occurred with a prevalence of 45% (n = 479), a mean intensity (± SE) of 2.3 ± 0.2 worms per infected eel (range = 1-22), and a mean abundance of 2.0 ± 0.1 among all eels. Infections by larval stages of A. crassus in the swimbladder wall occurred with a prevalence, intensity, and abundance of 29%, 2.4 ± 0.3 (range = 1-15), and 0.7 ± 0.1, respectively (n = 471). Overall prevalence of the parasite (any stage) was 58%, with a mean intensity ± SE of 3.0 ± 0.2 and a mean abundance of 1.8 ± 0.2. Biomass of the adult parasite stage varied significantly with eel body length, but the direction of the effect depended on salinity. Prevalence and intensity of infection by adult nematodes varied by locality but not by eel total length, salinity, or season. Larval prevalence was significantly greater in the winter and spring and also differed among localities. The lack of seasonal effects on infection by the adult worm stage contrasts with studies from higher latitudes in North America and Europe and may be due to the warmer winter temperatures at southern latitudes. Significant variation in infection among localities reflects possible differences in abundance of intermediate and/or paratenic hosts. Overall, infection levels were higher than previous reports for eels in SC but comparable to more recent reports from other areas in North America. PMID:24429471

  8. Area postrema, a brain circumventricular organ, is the site of antidipsogenic action of circulating atrial natriuretic peptide in eels.

    PubMed

    Tsukada, Takehiro; Nobata, Shigenori; Hyodo, Susumu; Takei, Yoshio

    2007-11-01

    Accumulating evidence indicates that circulating atrial natriuretic peptide (ANP) potently reduces excess drinking to ameliorate hypernatremia in seawater (SW) eels. However, the cerebral mechanism underlying the antidipsogenic effect is largely unknown. To localize the ANP target site in the brain, we examined the distribution of ANP receptors (NPR-A) in eel brain immunohistochemically using an antiserum specific for eel NPR-A. The immunoreactive NPR-A was localized in the capillaries of various brain regions. In addition, immunoreactive neurons were observed mostly in the medulla oblongata, including the reticular formation, glossopharyngeal-vagal motor complex, commissural nucleus of Cajal, and area postrema (AP). Trypan Blue, which binds serum albumin and does not cross the blood-brain barrier, was injected peripherally and stained the neurons in the AP but not other NPR-A immunopositive neurons. These histological data indicate that circulating ANP acts on the AP, which was further confirmed by physiological experiments. To this end, the AP in SW eels was topically destroyed by electric cauterization or were by chemical lesion of its neurons by kainic acid, and ANP (100 pmol kg(-1)) was then injected into the circulation. Both heat-coagulative and chemical lesions to the AP greatly reduced an antidipsogenic effect of ANP, but the ANP effect was retained in sham-operated eels and in those with lesions outside the AP. These results strongly suggest that the AP, a circumventricular organ without a blood-brain barrier, serves as a functional window of access for the circulating ANP to inhibit drinking in eels. PMID:17981865

  9. Larval Gnathostoma spinigerum Detected in Asian Swamp Eels, Monopterus albus, Purchased from a Local Market in Yangon, Myanmar

    PubMed Central

    Chai, Jong-Yil; Sohn, Woon-Mok; Na, Byoung-Kuk; Park, Jong-Bok; Jeoung, Hoo-Gn; Hoang, Eui-Hyug; Htoon, Thi Thi; Tin, Htay Htay

    2015-01-01

    The present study was performed to determine the infection status of swamp eels with Gnathostoma sp. larvae in Myanmar. We purchased total 37 Asian swamp eels, Monopterus albus, from a local market in Yangon in June and December 2013 and 2014. All collected eels were transferred with ice to our laboratory and each of them was examined by the artificial digestion technique. A total of 401 larval gnathostomes (1-96 larvae/eel) were detected in 33 (89.2%) swamp eels. Most of the larvae (n=383; 95.5%) were found in the muscle. The remaining 18 larvae were detected in the viscera. The advanced third-stage larvae (AdL3) were 2.3-4.4 mm long and 0.25-0.425 mm wide. The characteristic head bulb (0.093 × 0.221 mm in average size) with 4 rows of hooklets, muscular long esophagus (1.025 mm), and 2 pairs of cervical sacs (0.574 mm) were observed by light microscopy. The average number of hooklets in the 1st, 2nd, 3rd, and 4th rows was 41, 45, 48, and 51, respectively. As scanning electron microscopic findings, the characteristic 4-5 rows of hooklets on the head bulb, a cervical papilla, tegumental spines regularly arranged in the transverse striations, and an anus were well observed. Based on these morphological characters, they were identified as the AdL3 of Gnathostoma spinigerum. By the present study, it has been confirmed for the first time that Asian swamp eels, M. albus, from Yangon, Myanmar are heavily infected with G. spinigerum larvae. PMID:26537042

  10. Retiring the Silver Bullet

    SciTech Connect

    Lasure, Linda L.

    2006-01-01

    Over the past few decades, advances in biology and electronics have resulted in an enormous increase in the screening rate of new compounds and in the capacity to synthesize vast numbers of new compounds. The understanding of disease has greatly improved. At the same time, the number of targets (or diseases) for the silver bullets has also increased. Yet, the belief that we have to screen enormous numbers of compounds to find the next new drug continues. Today, disease is understood to be a complex interaction of many systems. This ought to cause us to change our paradigm, but it has not. The fundamental reason for the apparent failure of our drug discovery and development research is that we are operating under the constraints of an out-of-date paradigm. The silver-bullet paradigm has always been a myth. Now is the time to debunk the myth and change the paradigm. Our other option is to continue on as we are and accept that the United States will become obsolete on the playing field of drug discovery.

  11. A Silver DNAzyme.

    PubMed

    Saran, Runjhun; Liu, Juewen

    2016-04-01

    Silver is a very common heavy metal, and its detection is of significant analytical importance. DNAzymes are DNA-based catalysts; they typically recruit divalent and trivalent metal ions for catalysis. Herein, we report a silver-specific RNA-cleaving DNAzyme named Ag10c obtained after six rounds of in vitro selection. Ag10c displays a catalytic rate of 0.41 min(-1) with 10 μM Ag(+) at pH 7.5 with 200 mM NaNO3, while its activity is completely inhibited with the same concentration of NaCl. Ag10c is highly specific for Ag(+) among all the tested metals. A catalytic beacon biosensor is designed by labeling a fluorophore and a quencher on the DNAzyme. Fluorescence enhancement is observed in the presence of Ag(+) with a detection limit of 24.9 nM Ag(+). The sensor shows a similar analytical performance in Lake Huron water. This is the first monovalent transition metal dependent RNA-cleaving DNAzyme. Apart from its biosensor application, this study strengthens the idea of exploring beyond the traditional understanding of multivalent ion dependent DNAzyme catalysis. PMID:26977895

  12. Assessment of persistent brominated and chlorinated organic contaminants in the European eel (Anguilla anguilla) in Flanders, Belgium: Levels, profiles and health risk.

    PubMed

    Malarvannan, Govindan; Belpaire, Claude; Geeraerts, Caroline; Eulaers, Igor; Neels, Hugo; Covaci, Adrian

    2014-06-01

    Pooled yellow European eel (Anguilla anguilla (L.)) samples, consisting of 3-10 eels, collected between 2000 and 2009 from 60 locations in Flanders (Belgium) were investigated for persistent contaminants, such as polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane and its metabolites (DDTs). The current study expands the knowledge regarding these contaminant concentrations, their patterns and distribution profiles in aquatic ecosystems. PBDEs, HBCDs, PCBs, and DDTs were detected in all eel samples and some samples had high concentrations (up to 1400, 9500, 41,600 and 7000ng/g lw, respectively). PCB levels accounted for the majority of the contamination in most samples. The high variability in PBDE, HBCD, PCB and DDT concentrations reported here is likely due to the variety in sampling locations demonstrating variable local pollution pressures, from highly industrialised areas to small rural creeks. Among PBDEs, BDE-47 (57% contribution to the sum PBDEs), -100 (19%) and -99 (15%) were the predominant congeners, similar to the composition reported in the literature in eel samples. For HBCDs, α-HBCD (74%) was predominant followed by γ-(22%) and β-HBCD (4%) isomers in almost all eel samples. CB-153 (19%) was the most dominant PCB congener, closely followed by CB-138 (11%), CB-180 (9%), CB-187 (8%) and CB-149 (7%). The contribution to the total human exposure through local wild eel consumption was also highly variable. Intake of PBDEs and HBCDs, through consumption of wild eel, was below the RfD values for the average population (consuming on average 2.9g eel/day). At 16 out 60 sites, eels exceeded largely the new EU consumption threshold for PCBs (300ng/g ww for the sum of 6 indicator PCBs). The current data shows an on-going exposure of Flemish eels to PBDEs, HBCDs, PCBs and DDTs through indirect release from contaminated sediments or direct releases from various industries

  13. Process for making silver metal filaments

    DOEpatents

    Bamberger, Carlos E.

    1997-01-01

    A process for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles.

  14. Process for making silver metal filaments

    SciTech Connect

    Bamberger, C.E.

    1997-05-06

    A process is disclosed for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles. 1 fig.

  15. Parasite communities in eels of the Island of Reunion (Indian Ocean): a lesson in parasite introduction.

    PubMed

    Sasal, Pierre; Taraschewski, Horst; Valade, Pierre; Grondin, Henri; Wielgoss, Sébastien; Moravec, Frantisek

    2008-05-01

    Eel populations from the small rivers on the Island of Reunion (French Overseas Department in the Indian Ocean) were investigated with respect to the occurrence and abundance of helminths during the autumn of 2005. The native species Anguilla marmorata (n = 80), Anguilla bicolor (n = 23), and Anguilla mossambica (n = 15) were studied. Six species of helminths were identified, four of them having a definitely nonnative status. Furthermore, unidentified intra-intestinal juvenile cestodes and extra-intestinal encapsulated anisakid nematode larvae were present in a few eels. We found that the invasive swim bladder nematode Anguillicoloides (Anguillicola) crassus had been introduced into the island. Six specimens were collected, four from A. marmorata, one from A. bicolor and one from A. mossambica. The maximum intensity of infection was two worms. The other helminths also showed a low abundance. These species were the monogenean gill worms Pseudodactylogyrus anguillae and Pseudodactylogyrus bini and the intestinal parasites Bothriocephalus claviceps (Cestodes), Paraquimperia africana (Nematodes), and the acanthocephalan Acanthocephalus reunionensis Warner, Sasal, and Taraschewski, 2007. The latter species, found as intra-intestinal immatures, is thought to utilize amphibians as required hosts; its status, introduced or native, could not be determined. P. africana was described from A. mossambica in South Africa and has not been recorded outside Africa. The other species are known from populations of European and American eels. However, A. crassus and the two Pseudodactylogyrus species originate from East Asia, where they are indigenous parasites of Anguilla japonica. Both an assignment test based on seven specific microsatellite loci and subsequent sequencing of mitochondrial haplotypes of a partial fragment of cytochrome c oxidase 1 strongly suggest that the A. crassus may originated around the Baltic Sea. According to the results presented here, populations of the

  16. Phenolic Lipids Affect the Activity and Conformation of Acetylcholinesterase from Electrophorus electricus (Electric eel)

    PubMed Central

    Stasiuk, Maria; Janiszewska, Alicja; Kozubek, Arkadiusz

    2014-01-01

    Phenolic lipids were isolated from rye grains, cashew nutshell liquid (CNSL) from Anacardium occidentale, and fruit bodies of Merrulius tremellosus, and their effects on the electric eel acetylcholinesterase activity and conformation were studied. The observed effect distinctly depended on the chemical structure of the phenolic lipids that were available for interaction with the enzyme. All of the tested compounds reduced the activity of acetylcholinesterase. The degree of inhibition varied, showing a correlation with changes in the conformation of the enzyme tested by the intrinsic fluorescence of the Trp residues of the protein. PMID:24787269

  17. An improved white cell diluent for use with the Eel electronic blood cell counter.

    PubMed

    TAYLOR, F; RICKARDS, A G

    1960-05-01

    An improved white cell diluent for use with the Eel electronic counter is described. It possesses advantages over previously described diluents in the rapidity of its action as a red cell stromalysin and in its ability to conserve surviving leucocytes for long periods of time. These properties enable counts to be made either immediately after preparation of the suspension or several hours later. The diluent is equally suitable for use with capillary or venous blood samples. When used for counting leucocytes it has been found necessary to effect a minor modification to the machine whereby the light intensity is reduced by approximately one-half. PMID:13837137

  18. A new species of elongate unpatterned moray eel of the genus Gymnothorax (Muraenidae: Muraeninae) from the Bay of Bengal.

    PubMed

    Mohapatra, Anil; Ray, Dipanjan; Smith, David G; Mishra, Subhrendu Sekhar

    2016-01-01

    An elongate, brown unpatterned moray eel, Gymnothorax indicus sp. nov., is described based on four specimens collected from the northern Bay of Bengal. The new species is differentiated from other elongate, unpatterned moray eels in having the following combination of characters: anus at about mid-point of body, preanal length 2.0 in total length; snout blunt and short; dorsal fin margin black, 5 mandibular pores; maxillary teeth uniserial, sharp and depressible, total vertebrae 194 (MVF: 9-79-194). PMID:27615817

  19. Polymer glazing for silver mirrors

    SciTech Connect

    Neidlinger, H H; Schissel, P

    1985-07-01

    This paper reports on an evaluation and modification of polymeric glazings to protect silver mirrors. The mirrors were made using Corning 7809 glass as a substrate onto which a thin silver film is deposited. The modified polymeric films are then cast from solution onto the silver. The mirrors were characterized by measuring the hemispherical reflectance and the specular reflectance at 660 nm and selected acceptance angles (7.5 mrad or 3.5 mrad). The mirrors were exposed to environmental degradation using accelerated weathering devices and outdoor exposure. Empirical evidence has demonstrated that polymethylmethacrylate is a stable polymer in a terrestrial environment, but the polymer does not provide adequate protection for the silver reflector. The crucial role in degradation played by ultraviolet (uv) light is shown by several experimental results. It has been demonstrated that uv stabilizers added to the polymer improve the weatherability of mirrors. The relative effectiveness of different stabilizers will be discussed in terms of the weathering modes, retention of optical properties, and effectiveness of the additives. The process for silver deposition influences the reflectance of silver mirrors, and the optical properties depend on subtle relationships between the metallization and the dielectric (polymeric) films that are in contact with the silver.

  20. Female Reproductive System

    MedlinePlus

    ... Story" 5 Things to Know About Zika & Pregnancy Female Reproductive System KidsHealth > For Parents > Female Reproductive System Print A ... the egg or sperm. continue Components of the Female Reproductive System Unlike the male, the human female has a ...

  1. Silver Complexes of Dihalogen Molecules.

    PubMed

    Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

    2016-08-01

    The perfluorohexane-soluble and donor-free silver compound Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) prepared using a facile novel route has unprecedented capabilities to form unusual and weakly bound complexes. Here, we report on the three dihalogen-silver complexes Ag(Cl2 )A, Ag(Br2 )A, and Ag(I2 )A derived from the soluble silver compound Ag(A) (characterized by single-crystal/powder XRD, Raman spectra, and quantum-mechanical calculations). PMID:27404568

  2. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, G. M.; Vest, R. W.

    1985-01-01

    The feasibility of utilizing metallo-organic decomposition (MOD) silver inks were investigated for front contact metallization of solar cells. Generic synthesis procedures were developed for all metallo-organic compounds investigated. Silver neodecanoate was found to be the most suitable silver metallo-organic compound for use in thick film inks, but the quality of the inks was found to be highly dependent on its purity. Although neither the process nor inks were completely optimized for solar cell front contact metallization, they show great promise for this application.

  3. Experimental infection and detection of Aphanomyces invadans in European catfish, rainbow trout and European eel.

    PubMed

    Oidtmann, Birgit; Steinbauer, Peter; Geiger, Sheila; Hoffmann, Rudolf W

    2008-12-22

    European catfish Silurus glanis, European eel Anguilla anguilla and rainbow trout Oncorhynchus mykiss were challenged by intramuscular injection of zoospores of Aphanomyces invadans, the oomycete associated with epizootic ulcerative syndrome (EUS). The tropical three-spot gourami Trichogaster trichopterus is known to be highly susceptible and was used as a positive control. European catfish were highly susceptible and rainbow trout had moderate to low susceptibility, whereas eels appeared largely unaffected. Inflammatory host response in European catfish deviated from the effects seen in most other susceptible fish species and was characterised by a more loosely arranged accumulation of macrophages, small numbers of lymphocytes and multinucleated giant cells without occurrence of EUS-characteristic mycotic granulomas. Semi-nested and single round PCR assays were developed for this study to detect A. invadans DNA in clinical samples of experimentally infected fish. The detection limit of the assays equals 1 genomic unit. Specificity was examined by testing the DNA of various oomycetes, other relevant pathogens and commensals as well as host DNA. The single round assay used was fully specific, whereas cross-reaction with the closely related Aphanomyces frigidophilus was observed using the semi-nested assay. Analysis of samples by PCR allowed detection prior to detectable histopathological lesions. Two other published PCR protocols were compared to the PCR protocols presented here. PMID:19244971

  4. Fine-grained suspended sediment dynamics in the Eel River flood plume

    NASA Astrophysics Data System (ADS)

    Curran, Kristian J.; Hill, Paul S.; Milligan, Timothy G.

    2002-11-01

    Small rivers (drainage basins <10 4 km2) discharging runoff from mountainous terrain are major contributors of mud to the marine environment. However, little understanding of the dispersal mechanisms and fate of discharged fine-grained sediments to the continental shelf is known due to the episodic and unpredictable nature of discharge from these rivers. This study used a helicopter-based sampling program to capture unprecedented measures of Eel River, northern California, flood plume events during 1997, 1998, and 1999. In situ measures of floc size and estimated floc fraction show no relationship with concentration, turbulent-kinetic-energy, time from river mouth, wind speed, wave height, or discharge. A relationship apparently does exist between effective settling velocity (bulk mean settling velocity) of plume sediments and wind speed/direction, as well as with tides. Results implicate the energetic nearshore as a source of suspended sediment resupply to the offshore region of the plume. Future studies focusing on surf zone suspended fine-grained sediment dynamics are needed in order to understand the fate of flood plume sediments discharged to exposed, energetic shelves, such as the Eel River margin.

  5. Tectonic controls on sedimentation in the Eel River Basin: high-resolution CHIRP seismic data

    NASA Astrophysics Data System (ADS)

    Hogarth, L. J.; Driscoll, N. W.; Babcock, J. M.

    2007-12-01

    High-resolution CHIRP seismic data reveal the details of shore-parallel variations in Late-Pleistocene and Holocene sediments along the tectonically active Eel River Basin region, offshore Northern California. Shore- perpendicular deformation due to the northward migration of the Mendocino Triple Junction creates a tectonic signal with varying sign and amplitude oriented parallel to the coastline. This geometry provides an ideal opportunity to examine how tectonic deformation affects stratigraphic architecture and facies assemblages. Sediments are thinnest over the Little Salmon Anticline and systematically thicken towards the Eel Syncline. Seismic reflectors diverge into the syncline where sedimentary sections are expanded indicating tectonic deformation has been concurrent with sedimentation since the Last Glacial Maximum (LGM ~21,000 ka). We also observe offset on the transgressive surface above the thrust fault of the Little Salmon Anticline indicating fault displacement has occurred post transgression. While previous multi-channel seismic data sets from this region have detailed variation in the arrangement of facies and associated stratal geometry over the last several million years, this high-resolution CHIRP data set provides an opportunity to observe with greater resolution the formation of strata during the most recent deformation along this active margin.

  6. Probing the size dependence on the optical modes of anatase nanoplatelets using STEM-EELS.

    PubMed

    Liberti, Emanuela; Menzel, Robert; Shaffer, Milo S P; McComb, David W

    2016-05-14

    Anatase titania nanoplatelets with predominantly exposed {001} facets have been reported to have enhanced catalytic properties in comparison with bulk anatase. To understand their unusual behaviour, it is essential to fully characterize their electronic and optical properties at the nanometer scale. One way of assessing these fundamental properties is to study the dielectric function. Valence electron energy-loss spectroscopy (EELS) performed using a scanning transmission electron microscope (STEM) is the only analytical method that can probe the complex dielectric function with both high energy (<100 meV) and high spatial (<1 nm) resolution. By correlating experimental STEM-EELS data with simulations based on semi-classical dielectric theory, the dielectric response of thin (<5 nm) anatase nanoplatelets was found to be largely dominated by characteristic (optical) surface modes, which are linked to surface plasmon modes of anatase. For platelets less than 10 nm thick, the frequency of these optical modes varies according to their thickness. This unique optical behaviour prompts the enhancement of light absorption in the ultraviolet regime. Finally, the effect of finite size on the dielectric signal is gradually lost by stacking consistently two or more platelets in a specific crystal orientation, and eventually suppressed for large stacks of platelets. PMID:27113455

  7. Occurrence of perfluorooctanesulfonate and perfluorooctanoic acid and histopathology in eels from north Italian waters.

    PubMed

    Giari, Luisa; Guerranti, Cristiana; Perra, Guido; Lanzoni, Mattia; Fano, Elisa Anna; Castaldelli, Giuseppe

    2015-01-01

    A perfluorinated alkylated substances (PFAS) biomonitoring study was conducted in European eel (Anguilla anguilla) in Italy for the first time. Perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) concentrations were assessed in the organs of 35 wild eels from two locations, the highly impacted Po River and the Comacchio Lagoon along the north-western Adriatic coast. PFAS were extracted by ion-pairing liquid extraction procedure and measured using high performance liquid chromatography with electrospray ionization tandem mass spectrometry. There were no significant differences in mean PFAS concentrations (p>0.05) between samples from the two sites. PFOS and PFOA were detectable (>0.4ngg(-1) wet weight, w.w) in 73% and 31% of the total samples, respectively. PFOS concentrations ranged from <0.4 to 6.28ngg(-1)w.w and PFOA from <0.4 to 92.77ngg(-1)w.w. The highest PFAS levels were observed in blood and the lowest in muscle. Histology showed macrophage aggregates and hepatocytic vacuolation in some liver samples. No tissue anomalies were seen in the gonads, suggesting no reproductive impairment. The PFAS contamination levels observed were comparable to, or lower than, those reported in fish in other European countries, seeming to indicate that PFAS pollution of the study area is not remarkable. PMID:25083944

  8. Invading species in the Eel River, California: Successes, failures, and relationships with resident species

    USGS Publications Warehouse

    Brown, L.R.; Moyle, P.B.

    1997-01-01

    We examined invasions of non-native fishes into the Eel River, California. At least 16 species of fish have been introduced into the drainage which originally supported 12-14 fish species. Our study was prompted by the unauthorized introduction in 1979 of Sacramento squawfish, Ptychocheilus grandis, a large predatory cyprinid. From 1986 to 1990, we conducted growth and diet studies of squaw fish, conducted intensive surveys of the distribution and habitat associations of both native and introduced species, and examined the nature of species-habitat and interspecies relationships. We found no evidence for increased growth or expanded feeding habits, compared to native populations, of Sacramento squawfish as they invaded the Eel River drainage. Ten of the introduced species were well established, with four species limited to a reservoir and six species established in streams. The success or failure of introductions of stream species appeared to be a function of the ability of a species to survive the fluctuating, highly seasonal, flow regime. The present mixture of native and exotic species has not formed stable fish assemblages but it seems likely that four habitat-associated assemblages will develop. The overall effect of the successful species introductions has been to assemble a group of species, with some exceptions, that are native to and occur together in many California streams. The assemblages now forming are similar to those found in other California streams. The assemblage characterized by squawfish and suckers is likely to be resistant to invasion, in the absence of human caused habitat modifications.

  9. Evaluating the adaptive potential of the European eel: is the immunogenetic status recovering?

    PubMed Central

    Bracamonte, Seraina E.; Bayer, Till; Chain, Frédéric J.J.; Hanel, Reinhold; Harrod, Chris; Eizaguirre, Christophe

    2016-01-01

    The recent increased integration of evolutionary theory into conservation programs has greatly improved our ability to protect endangered species. A common application of such theory links population dynamics and indices of genetic diversity, usually estimated from neutrally evolving markers. However, some studies have suggested that highly polymorphic adaptive genes, such as the immune genes of the Major Histocompatibility Complex (MHC), might be more sensitive to fluctuations in population dynamics. As such, the combination of neutrally- and adaptively-evolving genes may be informative in populations where reductions in abundance have been documented. The European eel (Anguilla anguilla) underwent a drastic and well-reported decline in abundance in the late 20th century and still displays low recruitment. Here we compared genetic diversity indices estimated from neutral (mitochondrial DNA and microsatellites) and adaptive markers (MHC) between two distinct generations of European eels. Our results revealed a clear discrepancy between signatures obtained for each class of markers. Although mtDNA and microsatellites showed no changes in diversity between the older and the younger generations, MHC diversity revealed a contemporary drop followed by a recent increase. Our results suggest ongoing gain of MHC genetic diversity resulting from the interplay between drift and selection and ultimately increasing the adaptive potential of the species. PMID:27077000

  10. Cutaneous myxidiosis in European eel, Anguilla anguilla (Linnaeus, 1758): histopathology, histochemistry and laminin immunohistochemistry.

    PubMed

    Manera, M; Borreca, C; Dezfuli, B S

    2016-07-01

    Histopathology, histochemistry and immunohistochemistry of the integument of European eel, Anguilla anguilla (Linnaeus, 1758), infected by Myxidium sp. are reported. Skin samples from affected and unaffected eels were dissected, formalin fixed, paraffin embedded, sectioned and stained with H&E, Periodic acid-Schiff's staining method, Alcian Blue 8 GX pH 2.5/Periodic acid-Schiff's and McCallum-Goodpasture's Gram stain. Moreover, immunohistochemistry was performed using a primary polyclonal laminin antibody. Histologically, cysts (diameter 2-3 mm) were observed mainly under the scale pockets, encircled by a thin collagen layer, lined by elongated, flattened fibroblasts and containing bipolar, PAS- and Gram-positive spores with opposite polar capsules. The epidermis stretched by the underlying cyst appeared dysplastic, thinned with a significant reduction in mucous cells number. Only inconsistent and aspecific inflammatory reaction was noted around the cysts at the dermis/epidermis interface. Intense laminin-like protein immunolabel was documented in the plasmodial ectoplasm and related to host anergia. This was the first report of laminin immunolabel in a member of the Myxozoa. Epidermal dysplasia represents likely an aspecific response against the underlying tensile force exerted by the developing parasite cyst, while fibroblast and collagen encapsulation denote a parasite-driven host response protecting, rather than harming, the encircled parasite. PMID:26525491

  11. Complete mitogenome of two moray eels of Gymnothorax formosus and Scuticaria tigrina (Anguilliformes: Muraenidae).

    PubMed

    Loh, Kar-Hoe; Shao, Kwang-Tsao; Chen, Ching-Hung; Chen, Hong-Ming; Then, Amy Yee-Hui; Loo, Poh-Leong; Lim, Phaik-Eem; Chong, Ving-Ching; Shen, Kang-Ning; Hsiao, Chung-Der

    2016-07-01

    In this study, the complete mitogenome sequence of two moray eels of Gymnothorax formosus and Scuticaria tigrina (Anguilliformes: Muraenidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome, with the length of 16,558 bp for G. formosus and 16,521 bp for S. tigrina, shows 78% identity to each other. Both mitogenomes follow the typical vertebrate arrangement, including 13 protein coding genes, 22 transfer RNAs, two ribosomal RNAs genes, and a non-coding control region of D-loop. The length of D-loop is 927 bp (G. formosus) and 850 bp (S. tigrina), which is located between tRNA-Pro and tRNA-Phe. The overall GC content is 45.5% for G. formosus and 47.9% for S. tigrina. Complete mitogenomes of G. formosus and S. tigrina provide essential and important DNA molecular data for further phylogenetic and evolutionary analysis for moray eel. PMID:26029876

  12. Abundance of specific mRNA transcripts impacts hatching success in European eel, Anguilla anguilla L.

    PubMed

    Rozenfeld, Christoffer; Butts, Ian A E; Tomkiewicz, Jonna; Zambonino-Infante, Jose-Luis; Mazurais, David

    2016-01-01

    Maternal mRNA governs early embryonic development in fish and variation in abundance of maternal transcripts may contribute to variation in embryonic survival and hatch success in European eel, Anguilla anguilla. Previous studies have shown that quantities of the maternal gene products β-tubulin, insulin-like growth factor 2 (igf2), nucleoplasmin (npm2), prohibitin 2 (phb2), phosphatidylinositol glycan biosynthesis class F protein 5 (pigf5), and carnitine O-palmitoyltransferase liver isoform-like 1 (cpt1) are associated with embryonic developmental competence in other teleosts. Here, the relations between relative mRNA abundance of these genes in eggs and/or embryos and egg quality, was studied and analyzed. We compared egg quality of the two groups: i) batches with hatching and ii) batches with no hatching. Results showed no significant differences in relative mRNA abundance between the hatch and no hatching groups for any of the selected genes at 0, 2.5, and 5HPF. However, at 30HPF the hatch group showed significantly higher abundance of cpt1a, cpt1b, β-tubulin, phb2, and pigf5 transcripts than the no hatch group. Therefore, these results indicate that up-regulation of the transcription of these genes in European eel after the mid-blastula transition, may be needed to sustain embryonic development and hatching success. PMID:26415730

  13. Evidence of marine mammal predation of the European eel (Anguilla anguilla L.) on its marine migration

    NASA Astrophysics Data System (ADS)

    Wahlberg, Magnus; Westerberg, Håkan; Aarestrup, Kim; Feunteun, Eric; Gargan, Paddy; Righton, David

    2014-04-01

    Temperature and depth logging tags were implanted into adult eels released on Atlantic west coasts of France and Ireland to study their oceanic migration behavior. For three of the tags, 25 to 256 days after release there was a dramatic rise in temperature from 10 °C to 36 °C and the dive profile changed from depths of 300-1000 m to repeated ascents to the surface. This indicated that the eels carrying the tags had been eaten by a mammalian predator. Two of the tags had sufficient sampling rate to resolve the dives in detail. They recorded a total of 91 dives to maximum depths of 250-860 m lasting 11-12 min and with surface intervals of 5-7 min. More than two thirds of the dives included a rapid descent from approximately 500 m to 600-700 m. From this we infer that the predator was most likely a deep-diving toothed whale. The dives logged while the tags were inside the predator revealed that the temperature usually decreased during dives, and increased again during surface periods. The temperature drops during dives were probably caused by the ingestion of prey or water. These observations provide insights into the behavior of toothed whales foraging in the mesopelagic zone.

  14. Transcriptome profile analysis reveals specific signatures of pollutants in Atlantic eels.

    PubMed

    Baillon, Lucie; Pierron, Fabien; Coudret, Raphaël; Normendeau, Eric; Caron, Antoine; Peluhet, Laurent; Labadie, Pierre; Budzinski, Hélène; Durrieu, Gilles; Sarraco, Jérôme; Elie, Pierre; Couture, Patrice; Baudrimont, Magalie; Bernatchez, Louis

    2015-01-01

    Identifying specific effects of contaminants in a multi-stress field context remain a challenge in ecotoxicology. In this context, "omics" technologies, by allowing the simultaneous measurement of numerous biological endpoints, could help unravel the in situ toxicity of contaminants. In this study, wild Atlantic eels were sampled in 8 sites presenting a broad contamination gradient in France and Canada. The global hepatic transcriptome of animals was determined by RNA-Seq. In parallel, the contamination level of fish to 8 metals and 25 organic pollutants was determined. Factor analysis for multiple testing was used to identify genes that are most likely to be related to a single factor. Among the variables analyzed, arsenic (As), cadmium (Cd), lindane (γ-HCH) and the hepato-somatic index (HSI) were found to be the main factors affecting eel's transcriptome. Genes associated with As exposure were involved in the mechanisms that have been described during As vasculotoxicity in mammals. Genes correlated with Cd were involved in cell cycle and energy metabolism. For γ-HCH, genes were involved in lipolysis and cell growth. Genes associated with HSI were involved in protein, lipid and iron metabolisms. Our study proposes specific gene signatures of pollutants and their impacts in fish exposed to multi-stress conditions. PMID:25258179

  15. Silver Nafion for Thermogalvanic Applications

    NASA Astrophysics Data System (ADS)

    Chang, William; Popere, Bhooshan; Evans, Chris; Russ, Boris; Segalman, Rachel

    2015-03-01

    Thermogalvanics convert a temperature gradient, typically from waste heat, into electrical power using a reversible electrochemical reaction. The conversion efficiency in thermogalvanics, like with thermoelectrics, are governed by the Seebeck coefficient, the carrier conductivity and the thermal conductivity of the material. We demonstrate that the material systems silver Nafion and silver poly-styrenesulfonate are air-stable, water processable materials that demonstrate extremely high Seebeck coefficients and moderate carrier conductivities. These power factors, when coupled with the low thermal conductivities inherent in polymers, results in materials with excellent thermogalvanic figure of merits. We show the dependence of these three material properties to material composition and processing. In this talk, we show how the Seebeck coefficient in silver Nafion and silver polystyrene-sulfonate are opposite in sign, allowing construction of a thermogalvanic device. With these ion conductors, we hope to open up a flexible pathway to waste heat recovery using materials typically studied for electrochemical applications.

  16. Examining Substrate-Induced Plasmon Mode Splitting and Localization in Truncated Silver Nanospheres with Electron Energy Loss Spectroscopy.

    PubMed

    Li, Guoliang; Cherqui, Charles; Wu, Yueying; Bigelow, Nicholas W; Simmons, Philip D; Rack, Philip D; Masiello, David J; Camden, Jon P

    2015-07-01

    Motivated by the need to study the size dependence of nanoparticle-substrate systems, we present a combined experimental and theoretical electron energy loss spectroscopy (EELS) study of the plasmonic spectrum of substrate-supported truncated silver nanospheres. This work spans the entire classical range of plasmonic behavior probing particles of 20-1000 nm in diameter, allowing us to map the evolution of localized surface plasmons into surface plasmon polaritons and study the size dependence of substrate-induced mode splitting. This work constitutes the first nanoscopic characterization and imaging of these effects in truncated nanospheres, setting the stage for the systematic study of plasmon-mediated energy transfer in nanoparticle-substrate systems. PMID:26266735

  17. Characteristics and phylogenetic studies of complete mitochondrial DNA based on the ricefield eel (Monopterus albus) from four different areas.

    PubMed

    Chen, Dunxue; Chu, Wuying; He, Yan; Liang, Xu-Fang; Mai, Kangsen

    2016-07-01

    In this study, we cloned and sequenced the complete mitochondrial DNA of ricefield eel populations from four different areas (Guizhou province, Guangxi province, Hunan province, and Guangdong province) in China. The mitochondrial genome was 16,622 bp in length and deposited in the GenBank with accession numbers KP779622-KP779625. The organizations of the complete mitogenomes of the four ricefield eel were similar to those of other teleost species which contained 13 protein-coding genes, two rRNA genes, and 22 tRNA genes, as well as a putative control region (CR). Most of these genes were encoded on the H-strand, except for the ND6 and eight tRNA genes, all other genes were encoded on the H-strand. Phylogenetic analyses using N-J computational algorithms showed that the ricefield eel was clustered with Mastacembelus armatus (KJ184553) and they belong to Synbranchiformes. The four ricefield eel populations could be divided into two groups: Guangxi province and the other population cluster together. PMID:26258513

  18. Identification of a Testis-Enriched Heat Shock Protein and Fourteen Members of Hsp70 Family in the Swamp Eel

    PubMed Central

    He, Yan; Luo, Majing; Yi, Minhan; Sheng, Yue; Cheng, Yibin; Zhou, Rongjia; Cheng, Hanhua

    2013-01-01

    Background Gonad differentiation is one of the most important developmental events in vertebrates. Some heat shock proteins are associated with gonad development. Heat shock protein 70 (Hsp70) in the teleost fish and its roles in sex differentiation are poorly understood. Methods and Findings We have identified a testis-enriched heat shock protein Hspa8b2 in the swamp eel using Western blot analysis and Mass Spectrometry (MS). Fourteen Hsp70 family genes were further identified in this species based on transcriptome information. The phylogenetic tree of Hsp70 family was constructed using the Maximum Likelihood method and their expression patterns in the swamp eel gonads were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). Conclusion There are fourteen gene members in the Hsp70 family in the swamp eel genome. Hsp70 family, particularly Hspa8, has expanded in the species. One of the family members Hspa8b2 is predominantly expressed in testis of the swamp eel. PMID:23750249

  19. Microsatellite diversity in sympatric reproductive ecotypes of pacific steelhead (Oncorhynchus my kiss) from the Middle Fork Eel River, California

    USGS Publications Warehouse

    Nielsen, J.L.; Fountain, M.C.

    1999-01-01

    Genetic differentiation between two reproductive ecotypes of anadromous steelhead found in the Middle Fork Eel River in northern California was tested using 16 microsatellite loci. Twelve of these loci showed significant differences in allelic frequency between the two Middle Fork Eel River steelhead populations (Fisher's exact P<0.05). Fisher's combined test for independence also supported significant genetic separation between the two reproductive ecotype (P<0.001). Analysis of molecular variance indicated that only 1% of the overall microsatellite allelic variation contributed to differences between summer- and winter-run steelhead in the Middle Fork Eel River. Variation found among individuals within the two runs equaled 18.2%. Analyses showed less genetic distance between the two populations of steelhead in the Middle Fork Eel River than in comparisons made with geographically proximate coastal winter-run fish. Divergence time based on genetic distance for the two within-basin reproductive ecotypes was estimated to be 16,000-28,000 years ago. Copyright ?? Munksgaanl 1999.

  20. Preliminary flight prototype silver ion monitoring system

    NASA Technical Reports Server (NTRS)

    Brady, J.

    1974-01-01

    The design, fabrication, and testing of a preliminary flight prototype silver ion monitoring system based on potentiometric principles and utilizing a solid-state silver sulfide electrode paired with a pressurized double-junction reference electrode housing a replaceable electrolyte reservoir is described. The design provides automatic electronic calibration utilizing saturated silver bromide solution as a silver ion standard. The problem of loss of silver ion from recirculating fluid, its cause, and corrective procedures are reported. The instability of the silver sulfide electrode is discussed as well as difficulties met in implementing the autocalibration procedure.

  1. Adaptive Evolution of Eel Fluorescent Proteins from Fatty Acid Binding Proteins Produces Bright Fluorescence in the Marine Environment

    PubMed Central

    Gruber, David F.; Gaffney, Jean P.; Mehr, Shaadi; DeSalle, Rob; Sparks, John S.; Platisa, Jelena; Pieribone, Vincent A.

    2015-01-01

    We report the identification and characterization of two new members of a family of bilirubin-inducible fluorescent proteins (FPs) from marine chlopsid eels and demonstrate a key region of the sequence that serves as an evolutionary switch from non-fluorescent to fluorescent fatty acid-binding proteins (FABPs). Using transcriptomic analysis of two species of brightly fluorescent Kaupichthys eels (Kaupichthys hyoproroides and Kaupichthys n. sp.), two new FPs were identified, cloned and characterized (Chlopsid FP I and Chlopsid FP II). We then performed phylogenetic analysis on 210 FABPs, spanning 16 vertebrate orders, and including 163 vertebrate taxa. We show that the fluorescent FPs diverged as a protein family and are the sister group to brain FABPs. Our results indicate that the evolution of this family involved at least three gene duplication events. We show that fluorescent FABPs possess a unique, conserved tripeptide Gly-Pro-Pro sequence motif, which is not found in non-fluorescent fatty acid binding proteins. This motif arose from a duplication event of the FABP brain isoforms and was under strong purifying selection, leading to the classification of this new FP family. Residues adjacent to the motif are under strong positive selection, suggesting a further refinement of the eel protein’s fluorescent properties. We present a phylogenetic reconstruction of this emerging FP family and describe additional fluorescent FABP members from groups of distantly related eels. The elucidation of this class of fish FPs with diverse properties provides new templates for the development of protein-based fluorescent tools. The evolutionary adaptation from fatty acid-binding proteins to fluorescent fatty acid-binding proteins raises intrigue as to the functional role of bright green fluorescence in this cryptic genus of reclusive eels that inhabit a blue, nearly monochromatic, marine environment. PMID:26561348

  2. Theoretical investigations of silver clusters and silver-ligand systems.

    SciTech Connect

    Jellinek, J.; Salian, U.; Srinivas, S.

    1999-05-19

    Studies directed at understanding structural and electronic properties of silver clusters have been and remain the subject of an active theoretical [1-22] and experimental [23- 38] effort. One of the reasons is the (still) important role these systems play in the photographic process. Investigations of interactions of silver clusters with different atoms and molecules are motivated primarily by a possible utility of these clusters in catalytic processes. The important role of silver in the selective oxidation of ethylene into ethylene oxide, the feedstock for polyester production, is well-known [39]. Possible variations in chemical reactivity with the cluster size and understanding of the mechanisms of interactions with different ligands may lead to new and more efficient applications. Investigations of cluster-ligand systems also contribute a great deal to a better understanding of gas-surface interactions. Accordingly, theoretical studies of silver clusters and cluster-ligand systems [40-44] fall into two categories--those that use clusters as models for silver surfaces [40], and those that target clusters and cluster-ligand interactions as subjects in their own right [41-44]. The common goal of all these studies is to elucidate the nature of the interatomic interactions and bonding at the microscopic level and thereby arrive at a fundamental understanding and description of the various structural and electronic properties.

  3. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with ferrous... certification. Certification of this color additive is not necessary for the protection of the public health...

  4. Normal Female Reproductive Anatomy

    MedlinePlus

    ... hyphen, e.g. -historical Searches are case-insensitive Reproductive System, Female, Anatomy Add to My Pictures View /Download : Small: ... Reproductive System, Female, Anatomy Description: Anatomy of the female reproductive system; drawing shows the uterus, myometrium (muscular outer layer ...

  5. Growth promoting effect of hyaluronan synthesis promoting substances on Japanese eel leptocephali.

    PubMed

    Kawakami, Yutaka; Nomura, Kazuharu; Tanaka, Hideki

    2014-01-01

    Hyaluronans (HAs) are glycosaminoglycans produced in the bodies of Anguilliform and Elopiform leptocephali, and play a role in metabolic energy. In mammals, HA synthesis-promoting substances (HASPS) up-regulate the expression of HA synthase (HAS) and increase the amount of HA in the body. In this study, Japanese eel leptocephali were fed a HASPS containing diet. We analyzed HAS1s and HAS2 expression, HA content, and their influence on growth. HASPS extracted from Grifola frondosa promoted HAS1s and HAS2 mRNA and HA content. Other than mammals, these results are first reported in vertebrate. Moreover, HASPS extracted from G. frondosa promoted leptocephalus growth. The relationship between growth and HA in the leptocephali is not yet clear. However, based on our results we hypothesize that HA is involved in the storage of energy, which is metabolized to sugars when needed for metabolic energy. PMID:24896609

  6. Oxidation of a potassium monolayer on Ru(001) studied with photoemission, NEXAFS and vibrational EELS

    NASA Astrophysics Data System (ADS)

    Hoffmann, F. M.; Weisel, M.; Eberhardt, W.; Fu, Zugen

    1990-08-01

    The interaction of oxygen with a monolayer of potassium on a Ru(001) surface has been investigated with photoemission and NEXAFS. O 1s core-level data exhibit for low exposures of oxygen a single peak at 531.8 eV. This indicates together with the earlier observation of KO bond formation by EELS that a single K xO y species with equivalent oxygen atoms is formed. NEXAFS data indicate a partially filled O π* orbital and a strongly shifted σ-resonance. Photoemission, vibrational and Auger data suggest an ionic species which is close to potassium Superoxide with the OO bond oriented parallel to the surface.

  7. Probing the size dependence on the optical modes of anatase nanoplatelets using STEM-EELS

    NASA Astrophysics Data System (ADS)

    Liberti, Emanuela; Menzel, Robert; Shaffer, Milo S. P.; McComb, David W.

    2016-05-01

    Anatase titania nanoplatelets with predominantly exposed {001} facets have been reported to have enhanced catalytic properties in comparison with bulk anatase. To understand their unusual behaviour, it is essential to fully characterize their electronic and optical properties at the nanometer scale. One way of assessing these fundamental properties is to study the dielectric function. Valence electron energy-loss spectroscopy (EELS) performed using a scanning transmission electron microscope (STEM) is the only analytical method that can probe the complex dielectric function with both high energy (<100 meV) and high spatial (<1 nm) resolution. By correlating experimental STEM-EELS data with simulations based on semi-classical dielectric theory, the dielectric response of thin (<5 nm) anatase nanoplatelets was found to be largely dominated by characteristic (optical) surface modes, which are linked to surface plasmon modes of anatase. For platelets less than 10 nm thick, the frequency of these optical modes varies according to their thickness. This unique optical behaviour prompts the enhancement of light absorption in the ultraviolet regime. Finally, the effect of finite size on the dielectric signal is gradually lost by stacking consistently two or more platelets in a specific crystal orientation, and eventually suppressed for large stacks of platelets.Anatase titania nanoplatelets with predominantly exposed {001} facets have been reported to have enhanced catalytic properties in comparison with bulk anatase. To understand their unusual behaviour, it is essential to fully characterize their electronic and optical properties at the nanometer scale. One way of assessing these fundamental properties is to study the dielectric function. Valence electron energy-loss spectroscopy (EELS) performed using a scanning transmission electron microscope (STEM) is the only analytical method that can probe the complex dielectric function with both high energy (<100 meV) and high

  8. Local Probe into the Atomic Structure of Metallic Glasses using EELS

    SciTech Connect

    Alamgir, F.M.; Ito, Y. Schwarz, R.B.

    1999-11-30

    Electron energy loss spectroscopy (EELS) is used to extract information on the topological arrangement of atoms around Pd in the bulk-glass-forming Pd{sub 60}Ni{sub 20}P{sub 20}. It is found that the environment around Pd in the glass is only a slight modification of the Pd crystalline structure. However, the modification is enough to allow this alloy to form a glass in bulk. In examining the differences between the structure of crystalline Pd and glassy Pd{sub 60}Ni{sub 20}P{sub 20} it is concluded that incorporation of Ni and P into the structure frustrates the structure enough that glass formation becomes easy.

  9. Comparison of offshore and onshore gas occurrences, Eel River basin, northern California

    USGS Publications Warehouse

    Lorenson, T.D.; McLaughlin, Robert J.; Kvenvolden, Keith A.; Orange, Daniel L.; Davisson, M. Lee; Brewer, Peter G.; Martin, J.B.

    1998-01-01

    The Eel River basin of northern California is a upper Cenozoic depocenter containing more than 3,000 meters of sedimentary rock located near the Mendocino triple junction. Active tectonism has resulted in folding, faulting and rapid sedimentation. Both thermogenic and microbial hydrocarbons are known to be present in the sediments. In August 1997, we sampled two submarine gas seeps, one at a water depth of 520 m that supports a chemosynthetic-based ecosystem very near an area of previously recovered gas hydrate. Another vent site was sampled in sand covered with white bacterial mats at a water depth 41 m. We compared the hydrocarbon gas composition and methane isotopic composition of these seeps with land-based gas occurrences that include: 1) a gas seep and 2) gas from a 2360 m-deep gas well.

  10. Flood inundation maps for the Wabash and Eel Rivers at Logansport, Indiana

    USGS Publications Warehouse

    Fowler, Kathleen K.

    2014-01-01

    Digital flood-inundation maps for an 8.3-mile reach of the Wabash River and a 7.6-mile reach of the Eel River at Logansport, Indiana (Ind.), were created by the U.S. Geological Survey (USGS) in cooperation with the Indiana Office of Community and Rural Affairs. The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at USGS streamgage Wabash River at Logansport, Ind. (sta. no. 03329000) and USGS streamgage Eel River near Logansport, Ind. (sta. no. 03328500). Current conditions for estimating near-real-time areas of inundation using USGS streamgage information may be obtained on the Internet at http://waterdata.usgs.gov/. In addition, information has been provided to the National Weather Service (NWS) for incorporation into their Advanced Hydrologic Prediction Service (AHPS) flood warning system http:/water.weather.gov/ahps/). The NWS forecasts flood hydrographs at many places that are often colocated with USGS streamgages. NWS-forecasted peak-stage information may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. For this study, flood profiles were computed for the stream reaches by means of a one-dimensional step-backwater model developed by the U.S. Army Corps of Engineers. The hydraulic model was calibrated by using the most current stage-discharge relations at USGS streamgages 03329000, Wabash River at Logansport, Ind., and 03328500, Eel River near Logansport, Ind. The calibrated hydraulic model was then used to determine five water-surface profiles for flood stage at 1-foot intervals referenced to the Wabash River streamgage datum, and four water-surface profiles for flood stages at 1-foot intervals referenced to the Eel River streamgage datum. The stages range from bankfull to approximately the highest

  11. Electron Energy-Loss Spectroscopy (EELS) of Fe-bearing Sheet Silicates in CM Chondrites

    NASA Technical Reports Server (NTRS)

    Zega, Thomas J.; Garvie, Laurence A. J.; Buseck, Peter R.

    2003-01-01

    The primitive character and hydrated mineralogy of the CM chondrites offers insight into some of the earliest reactions between solids and water. Such reactions profoundly affected the matrices and fine-grained rims (FGRs) [1-4], two of the most significant components of these meteorites [5]. We are using EELS combined with a transmission electron microscope (TEM) to investigate the compositions of Fe-bearing minerals, with emphasis on determining oxidation states and quantification of oxidation-state ratios. Iron is among the most abundant elements in the solar system and it can occur naturally in three oxidation states: Fe0, Fe2+, and Fe3+. Determination of oxidation- state ratios is useful because they can be used to infer the redox conditions under which the minerals formed or were last equilibrated [6, 7]. We are particularly interested in understanding how the oxidation state of Fe was affected by the aqueous reactions of the CM chondrites.

  12. Investigating the Electronic Structure of Fluorite Oxides: Comparsion of EELS and First Principles Calculations

    SciTech Connect

    Aguiar, J; Asta, M; Gronbech-Jensen, N; Perlov, A; Milman, V; Gao, S; Pickard, C; Browning, N

    2009-06-05

    Energy loss spectra from a variety of cubic oxides are compared with ab-initio calculations based on the density functional plane wave method (CASTEP). In order to obtain agreement between experimental and theoretical spectra, unique material specific considerations were taken into account. The spectra were calculated using various approximations to describe core-hole effects and electronic correlations. All the calculations are based on the local spin density approximation to show qualitative agreement with the sensitive oxygen K-edge spectra in ceria, zirconia, and urania. Comparison of experimental and theoretical results let us characterize the main electronic interactions responsible for both the electronic structure and the resulting EEL spectra of the compounds in question.

  13. A new deepwater species of the snake eel genus Ophichthus (Anguilliformes: Ophichthidae) from North Carolina

    USGS Publications Warehouse

    McCosker, J.E.; Ross, S.W.

    2007-01-01

    Ophichthus brevirostris, a new species of snake eel, subfamily Ophichthinae, is described from a specimen trawled in deep water (406-440 m) off North Carolina. It is distinguished from its congeners by the following combination of characters: large orbit; filamentous pectoral fin; two preopercular pores; short snout; minute dentition; body coloration; and vertebral formula (13/60/153). It is most similar to Ophichthus arneutes from the Gala??pagos, O. genie from New Caledonia and Maldives, and two undescribed congeners from Seychelles and Tonga. It differs from them in its dorsalfin origin, dentition, and vertebral numbers. Its characteristics do not agree with that of any of the 15 known leptocephali of western Atlantic relatives. ?? 2007 by the American Society of Ichthyologists and Herpetologists.

  14. Accumulation and dissipation of organosulfur compounds in short-necked clam and eel

    SciTech Connect

    Ogata, M.; Miyake, Y.; Fujisawa, K.; Kira, S.; Yoshida, Y.

    1980-07-01

    The transfer of organosulfur compounds to short-necked clam and eel, and their elimination from contaminated biota after being transferred and reared in clean sea water have been reported. Furthermore, the compounds transferred to fish or shellfish from crude oil suspension have been identified by a gas chromatograph-mass spectrometer and by a gas chromatograph-mass spectrometer attached with computer system. Thereafter, the organosulfur compounds found in marine biota have been presumed as indices of contamination by petroleum or crude oil. In the present report, the experiment was designed to examine the tendencies of accumulation and elimination of several organosulfur compounds in marine biota kept in oil contaminated water or in clean sea water after the contamination. The obtained data were analyzed by curve fit method, the concentration ratio versus rearing time, concentration factor and half-life of each identified organosulfur compound was calculated.

  15. Relaxation of ferroelectric states in 2D distributions of quantum dots: EELS simulation

    NASA Astrophysics Data System (ADS)

    Cortés, C. M.; Meza-Montes, L.; Moctezuma, R. E.; Carrillo, J. L.

    2016-06-01

    The relaxation time of collective electronic states in a 2D distribution of quantum dots is investigated theoretically by simulating EELS experiments. From the numerical calculation of the probability of energy loss of an electron beam, traveling parallel to the distribution, it is possible to estimate the damping time of ferroelectric-like states. We generate this collective response of the distribution by introducing a mean field interaction among the quantum dots, and then, the model is extended incorporating effects of long-range correlations through a Bragg–Williams approximation. The behavior of the dielectric function, the energy loss function, and the relaxation time of ferroelectric-like states is then investigated as a function of the temperature of the distribution and the damping constant of the electronic states in the single quantum dots. The robustness of the trends and tendencies of our results indicate that this scheme of analysis can guide experimentalists to develop tailored quantum dots distributions for specific applications.

  16. Green synthesis of silver nanoparticles for the control of mosquito vectors of malaria, filariasis, and dengue.

    PubMed

    Arjunan, Naresh Kumar; Murugan, Kadarkarai; Rejeeth, Chandrababu; Madhiyazhagan, Pari; Barnard, Donald R

    2012-03-01

    A biological method was used to synthesize stable silver nanoparticles that were tested as mosquito larvicides against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Annona squamosa leaf broth (5%) reduced aqueous 1 mM AgNO₃ to stable silver nanoparticles with an average size of 450 nm. The structure and percentage of synthesized nanoparticles was characterized by using ultraviolet spectrophotometry, X-Ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy methods. The median lethal concentrations (LC₅₀) of silver nanoparticles that killed fourth instars of Ae. aegypti, Cx. quinquefasciatus, and An. stephensi were 0.30, 0.41, and 2.12 ppm, respectively. Adult longevity (days) in male and female mosquitoes exposed as larvae to 0.1 ppm silver nanoparticles was reduced by ~30% (p<0.05), whereas the number of eggs laid by females exposed as larvae to 0.1 ppm silver nanoparticles decreased by 36% (p<0.05). PMID:22022807

  17. Salinity tolerance of non-native Asian swamp eels (Teleostei: Synbranchidae) in Florida, USA: Comparison of three populations and implications for dispersal

    USGS Publications Warehouse

    Schofield, P.J.; Nico, L.G.

    2009-01-01

    Three populations of non-native Asian swamp eels are established in peninsular Florida (USA), and comprise two different genetic lineages. To assess potential for these fish to penetrate estuarine habitats or use coastal waters as dispersal routes, we determined their salinity tolerances. Swamp eels from the three Florida populations were tested by gradual (chronic) salinity increases; additionally, individuals from the Miami population were tested by abrupt (acute) salinity increases. Results showed significant tolerance by all populations to mesohaline waters: Mean survival time at 14 ppt was 63 days. The Homestead population, a genetically distinct lineage, exhibited greater tolerance to higher salinity than Tampa and Miami populations. Acute experiments indicated that swamp eels were capable of tolerating abrupt shifts from 0 to 16 ppt, with little mortality over 10 days. The broad salinity tolerance demonstrated by these experiments provides evidence that swamp eels are physiologically capable of infiltrating estuarine environments and using coastal waters to invade new freshwater systems. ?? 2009 US Government.

  18. Endoscopic evaluation and biopsy collection of the gastrointestinal tract in the green moray eel (Gymnothorax funebris): application in a case of chronic regurgitation with gastric mucus gland hyperplasia.

    PubMed

    Meegan, Jenny; Sidor, Inga F; Field, Cara; Roddy, Nicole; Sirpenski, Gayle; Dunn, J Lawrence

    2012-09-01

    A green moray eel (Gymnothorax funebris) was evaluated for chronic regurgitation. By using flexible endoscopy, the gastrointestinal tract was evaluated and revealed multifocal proliferative gastric masses and an intestinal ulcer. Biopsy specimens revealed gastric mucus gland hyperplasia, intestinal nematodiasis, and mild enteritis. Esophagoscopy and gastroscopy were performed by using a larger endoscope (length, 200 cm). A smaller endoscope (length, 100 cm) facilitated entering the intestinal tract in normograde or retrograde directions. A control eel was also evaluated, and no gross or histologic abnormalities were detected. The case eel was treated with metoclopramide and fenbendazole, responded well to therapy, and regurgitation decreased. A year later, the animal died of unrelated causes. Necropsy revealed coelomic gastric adhesions. The gastric proliferative lesions were associated with degeneration and necrosis of gastric pit mucosa without significant inflammation; etiology was unknown. Gastrointestinal endoscopy proved a useful diagnostic tool for evaluation and biopsy collection in this eel species. PMID:23082527

  19. Improvement of European eel sperm cryopreservation method by preventing spermatozoa movement activation caused by cryoprotectants.

    PubMed

    Peñaranda, D S; Pérez, L; Gallego, V; Jover, M; Asturiano, J F

    2009-10-01

    Sperm production has been obtained from European and Japanese eels, but its quality and quantity tend to be changeable. So, its cryopreservation has been tried in both species. Dimethyl sulfoxide (Me(2)SO) is the best cryoprotectant for European eel sperm, but increases the medium osmolality, inducing the activation of spermatozoa motility. To avoid this, different combinations of pH (6.5 and 8.5) and NaHCO(3) concentrations (20, 40 and 80mM) were tested with two Me(2)SO concentrations (5% and 10%). Foetal bovine serum (FBS, 25%v/v) was added as a membrane protector to all the freezing media used in the different experiments. The highest Me(2)SO and NaHCO(3) concentrations at pH 6.5 caused the best post-thawing motility (26+/-4%). A second experiment was carried out testing media with Me(2)SO 10% with additional NaHCO(3) concentrations (100 and 120 mM). The highest post-thawing motility (38+/-3%) was found in the media containing NaHCO(3) 100mM, but no significant difference was observed compared with the best in the previous experiment (NaHCO(3) 80 mM). In a parallel experiment, aiming to improve the protection against the cryopreservation process, bovine serum albumin (BSA, 5%w/v) was added instead of FBS. Lower motilities were registered with BSA as membrane protector. Spermatozoa activation caused by addition of Me(2)SO can be prevented using high NaHCO(3) concentrations, improving the cryopreservation process. This effect seems be based on some of the products dissociated from NaHCO(3) in aqueous solution, affecting the intracellular pH, essential in the sperm motility. PMID:19508865

  20. Speciation and demographic history of Atlantic eels (Anguilla anguilla and A. rostrata) revealed by mitogenome sequencing.

    PubMed

    Jacobsen, M W; Pujolar, J M; Gilbert, M T P; Moreno-Mayar, J V; Bernatchez, L; Als, T D; Lobon-Cervia, J; Hansen, M M

    2014-11-01

    Processes leading to speciation in oceanic environments without obvious physical barriers remain poorly known. European and American eel (Anguilla anguilla and A. rostrata) spawn in partial sympatry in the Sargasso Sea. Larvae are advected by the Gulf Stream and other currents towards the European/North African and North American coasts, respectively. We analyzed 104 mitogenomes from the two species along with mitogenomes of other Anguilla and outgroup species. We estimated divergence time between the two species to identify major events involved in speciation. We also considered two previously stated hypotheses: one where the ancestral species was present in only one continent but was advected across the Atlantic by ocean current changes and another where population declines during Pleistocene glaciations led to increasing vicariance, facilitating speciation. Divergence time was estimated to ∼3.38 Mya, coinciding with the closure of the Panama Gateway that led to reinforcement of the Gulf Stream. This could have advected larvae towards European/North African coasts, in which case American eel would be expected to be the ancestral species. This scenario could, however, not be unequivocally confirmed by analyses of dN/dS, nucleotide diversity and effective population size estimates. Extended bayesian skyline plots showed fluctuations of effective population sizes and declines during glaciations, and thus also lending support to the importance of vicariance during speciation. There was evidence for positive selection at the ATP6 and possibly ND5 genes, indicating a role in speciation. The findings suggest an important role of ocean current changes in speciation of marine organisms. PMID:24865601

  1. Pharmacokinetics and residue depletion of praziquantel in rice field eels Monopterus albus.

    PubMed

    Xu, Ning; Dong, Jing; Yang, Yibin; Ai, Xiaohui

    2016-04-12

    We investigated the pharmacokinetic characteristics of praziquantel (PZQ) in rice field eels Monopterus albus. Pharmacokinetic parameters were determined following a single intravenous administration (5 mg kg(-1) body weight [bw]) and a single oral administration (10 mg kg(-1) bw) at 22.0 ± 0.7°C. We also evaluated residue depletion in tissues following daily administration of PZQ (10 mg kg(-1) bw) that was given orally for 3 consecutive days at 22.0 ± 0.7°C. Following intravenous treatment, the plasma concentration-time curve was best described by a 3-compartment open model, with distribution half-life (t(1/2α)), elimination half-life (t(1/2β)), and area under the concentration-time curve (AUC) of 0.54 h, 17.10 h, and 14505.12 h µg l(-1), respectively. After oral administration, the plasma concentration-time curve was best described by a 1-compartment open model with first-order absorption, with absorption half-life (t(1/2Ka)), elimination half-life (t(1/2Ke)), peak concentration (C(max)), time-to-peak concentration (T(max)), and AUC estimated to be 2.28 h, 6.66 h, 361.29 µg l(-1), 5.36 h, and 6065.46 h µg l(-1), respectively. The oral bioavailability (F) was 20.9%. With respect to residue depletion of PZQ, the t(1/2β) values of muscle, skin, liver, and kidney were 20.2, 28.4, 14.9, and 54.1 h, respectively. Our results indicated rapid absorption, rapid elimination, and low bioavailability of PZQ in rice field eels at the tested dosing conditions. PMID:27068504

  2. Chemical Composition of Organic Matter in Surface Sediments of the Eel River Shelf Depocenter

    NASA Astrophysics Data System (ADS)

    Smith, S. D.; Goni, M. A.; Borgeld, J.; Wheatcroft, R. A.

    2011-12-01

    Small mountainous river systems (SMRS) export large amounts of sediment from the continents to the ocean, where they typically accumulate in shelf depocenters. These depositional environments have the potential to provide high resolution records of past conditions in both land and coastal ocean because they sequester OM derived from both terrigenous as well as marine sources. In this study we investigate the distribution and composition of OM in surface sediments from shelf depocenter associated with the Eel River, a high-sediment yield SMRS in Northern California. To characterize OM in these samples a combination of elemental (e.g., %OC, C/N), isotopic (e.g., d13C, d15N, D14C) and biomarker (e.g., lignin and non-lignin derived CuO products) analyses were used. Marked contrast in the overall contents of OC and both terrigenous and marine biomarkers were found as a function of depth, reflecting well established cross-shelf trends in grain size and accumulation rates. Source indicators show terrigenous sources make up a major fraction of the OM in surface sediments with peak contributions in the highest accumulation region of the depocenter. The composition of the terrigenous OM in shelf sediments is distinct from the compositions previously determined for the suspended load of the Eel River, including higher lignin yields and a more conifer-like signature. Possible reasons include biologic (e.g., preferential degradation) and physical (e.g., hydrodynamic sorting) alteration of the river suspended load during transport to its ultimate accumulation site. Additionally, it is also likely that the signatures measured in the depocenter reflect the input of material during large floods, which have not been characterized by the river sampling to date. We discuss the implications of these findings from the point of view of reconstructing watershed conditions and processes using depocenter sediment records.

  3. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity...

  4. Fluorescent silver nanoclusters stabilized by DNA scaffolds.

    PubMed

    Yuan, Zhiqin; Chen, Ying-Chieh; Li, Hung-Wen; Chang, Huan-Tsung

    2014-09-01

    Fluorescent silver nanoclusters, in particular DNA stabilized (templated) silver nanoclusters, have attracted much attention because of their molecule-like optical properties, strong fluorescence and good biocompatibility. In this feature article, we summarize the DNA stabilized silver nanoclusters from the viewpoints of synthesis, optical properties, as well as recent applications in biological detection and imaging. PMID:24901353

  5. The Myth of the Silver Surfer

    ERIC Educational Resources Information Center

    Gorard, Stephen; Selwyn, Neil

    2008-01-01

    In this article, the authors write about the myth of the "silver surfers"--those third-age learners adept at using the internet and other technologies for a mixture of formal and informal learning episodes. The notion of the silver surfer has endured since the latter half of the 1990s. It is sustained by the annual Silver Surfer week, media…

  6. Influence of the North Atlantic oceanograghic and climatic parameters on the Spanish European Eel population recruitment: relationships in the past and for a future climate change

    NASA Astrophysics Data System (ADS)

    Ribalaygua, Jaime; Pórtoles, Javier; Monjo, Robert; Díaz, Estíbaliz; Korta, María; Chust, Guillem

    2016-04-01

    The status of the European eel population is critical.; the annual recruitment of glass eel to European waters in 2015 is 1.2% of the 1960-1979 level in the 'North Sea' area, and 8.4% in the rest of Europe (ICES 2015) . There are a number of anthropogenic impacts potentially affecting eel population including commercial exploitation, habitat loss, dam and weir construction, hydropower, pumping stations and surface water abstractions. Furthermore, the first eel stages and larval migration and marine survival are heavily influenced by oceanic and climatic factors since the species breeds in the Sargasso Sea and migrates to the continental shelf of the Atlantic coast of Europe and North Africa. Therefore, the study of the relations between recruitment and oceanic conditions may allow to study the potential effect of climatic change on the future eel recruitment and therefore stock. In the present study, the relation between glass eel recruitment and oceanic and climatic factors has been studied. Historic glass eel catches data beginning in the 50s from two Mediterranean and two Atlantic estuaries have been used as a proxy of recruitment. The relation of catches with the main oceanographic and climatic factors identified in the literature was established using an ocean reanalysis, the Simple Ocean Data Assimilation (SODA) and determined which variables are significantly related to the number of catches. The analysis shows significant relationships between catches and oceanic (Surface Downward Stress, Sea Water Temperature and Sea Water Velocity) and atmospheric (NAO Index, AMO Index) variables. Subsequently, we applied the results of three climate models (GFDL-ESM2M, CanESM2 and CNRM-CM5), associated with the Coupled Model Intercomparison Project Phase 5 (CMIP5) under two simulations of climate change (RCP4.5 and RCP8.5), both associated with the 5th Assessment Report of the IPCC, for possible future influences on the eel. This research was funded by the Spanish

  7. Geometrical parameters effects on local electric field enhancement of silver-dielectric-silver multilayer nanoshell

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-05-15

    The local electric field enhancement at different points of silver-dielectric-silver nanoshell is investigated using quasi-static theory. Because of the symmetric and anti-symmetric coupling between surface plasmon of inner silver core and outer silver shell, the local electric field spectrum of silver-dielectric-silver has two distinct peaks at resonance wavelengths. The silver core size and middle dielectric thickness affect the local electric field enhancement at different points of silver-dielectric-silver nanoshell. Increasing the silver core radius always leads to blue shift of shorter resonance wavelength and red shift of longer resonance wavelength. We observed two distinct local electric field peaks, which are corresponded to the symmetric and anti-symmetric coupling between inner and outer surface plasmons. In a system with thick silver shell, local electric field enhancement is greater than a system with thin silver shell. However, the local electric field variations as a function of silver core radius in both systems are different at different points of nanoshell. The effects of the dielectric thickness variations on local electric field are different from those from silver core size variations. As the dielectric thickness is about 3 nm, the highest local electric field enhancement occurs at the surface of the inner silver core, where the symmetric and anti-symmetric modes are mixed together.

  8. Geometrical parameters effects on local electric field enhancement of silver-dielectric-silver multilayer nanoshell

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-05-01

    The local electric field enhancement at different points of silver-dielectric-silver nanoshell is investigated using quasi-static theory. Because of the symmetric and anti-symmetric coupling between surface plasmon of inner silver core and outer silver shell, the local electric field spectrum of silver-dielectric-silver has two distinct peaks at resonance wavelengths. The silver core size and middle dielectric thickness affect the local electric field enhancement at different points of silver-dielectric-silver nanoshell. Increasing the silver core radius always leads to blue shift of shorter resonance wavelength and red shift of longer resonance wavelength. We observed two distinct local electric field peaks, which are corresponded to the symmetric and anti-symmetric coupling between inner and outer surface plasmons. In a system with thick silver shell, local electric field enhancement is greater than a system with thin silver shell. However, the local electric field variations as a function of silver core radius in both systems are different at different points of nanoshell. The effects of the dielectric thickness variations on local electric field are different from those from silver core size variations. As the dielectric thickness is about 3 nm, the highest local electric field enhancement occurs at the surface of the inner silver core, where the symmetric and anti-symmetric modes are mixed together.

  9. Durable silver coating for mirrors

    DOEpatents

    Wolfe, Jesse D.; Thomas, Norman L.

    2000-01-01

    A durable multilayer mirror includes reflective layers of aluminum and silver and has high reflectance over a broad spectral range from ultraviolet to visible to infrared. An adhesion layer of a nickel and/or chromium alloy or nitride is deposited on an aluminum surface, and a thin layer of silver is then deposited on the adhesion layer. The silver layer is protected by a passivation layer of a nickel and/or chromium alloy or nitride and by one or more durability layers made of metal oxides and typically a first layer of metal nitride. The durability layers may include a composite silicon aluminum nitride and an oxinitride transition layer to improve bonding between nitride and oxide layers.

  10. Sulfidation of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Levard, C.; Michel, F. M.; Brown, G. E.

    2010-12-01

    Rapid development of nanotechnologies that exploit the properties of silver nanoparticles (Ag-NPs) raises questions concerning the impact of Ag on the environment. Ag-NPs are currently among the most widely used in the nanotechnology industry and the amount released into the environment is expected to increase along with production (1). When present in geochemical systems, Ag-NPs may undergo a variety of changes due to varying redox, pH, and chemical conditions. Expected changes range from surface modification (e.g., oxidation, sulfidation, chloridation etc.) to complete dissolution and re-precipitation. In this context, the focus of our work is on understanding the behavior of synthetic Ag-NPs with different particle sizes under varying conditions relevant to the environment. Sulfidation of Ag-NPs is of particular interest since it among the processes most likely to occur in aqueous systems, in particular under reducing conditions. Three sizes of Ag-NPs coated with polyvinyl pyrrolidone were produced using the polyol process (2) (7 ±1; 20 ±4, and 40 ±9 nm). Batch solutions containing the different Ag-NPs were subsequently reacted with Na2S solutions of different concentrations. The sulfidation process was followed step-wise for 24 hours and the corrosion products formed were characterized by electron microscopy (TEM/SEM), diffraction (XRD), and photo-electron spectroscopy (XPS). Surface charge (pHPZC) of the products formed during this process was also measured, as were changes in solubility and reactivity. Based on experimental observations we infer that the sulfidation process is the result of dissolution-precipitation and find that: (i) acanthite (Ag2S) is formed as a corrosion product; (ii) Ag-NPs aggregation increased with sulfidation rate; (iii) pHPZC increases with the rate of sulfidation; and (iv) the solubility of the corrosion products formed from sulfidation appears lower than that of non-sulfidated Ag-NPs. We observe size-dependent differences in

  11. A preliminary observation on the pond culture of European eel, Anguilla anguilla (Linnaeus, 1758) in Egypt: recommendations for future studies.

    PubMed

    El-Shebly, Abdalla A; El-kady, Mohamed A H; Hossain, M Yeamin

    2007-04-01

    An experiment was conducted to assess the potential of the European eel, Anguilla anguilla for earthen pond aquaculture without supplementary feeding at Lake Manzala, Egypt. Juvenile A. anguilla of mean length 11.7 cm and 2.4 g weight were stocked in earthen ponds measuring 3 feddans (about 12,600 m2) and 1 m deep. Stocking was done in May 2003 at a rate of 5000 fish feddan(-1) in a polyculture system including tilapia and mullets and fed mainly on natural occurring prey (natural spawned tilapia) and small shrimp. The eels were culture for a period of 2 years, May 2003 to April 2005. Sampling for growth and survival were evaluated yearly. At the end of the culture period, the gross weight of the harvested eels was measured and the net pond production calculated by the difference between weight stocked and weight harvested. Temperature varied from 11.5 to 28.2 degrees C and 12.2 to 29.3 degrees C; P(H), 7.3 to 8.9 and 7.5 to 8.8; Dissolved Oxygen (DO), 5.2 to 9.8 mg L(-1) and 4.1 to 8.3 mg L(-1); and Salinity, 2.5 to 5.5 psu and 3.0 to 6.8 psu for first year and second year, respectively. At the end of the culture period, A. anguilla attained average weight of 121.4 g fish(-1) at the end of the first year and a weight range of 152.5 to 430 g fish(-1) with an average of 280.36 g fish(-1) at the end of the second year. Survival rate ranged from 91% during the first year to 100% during the second year. Net eel production was 540.18 kg feddan(-1) at the end of the first year and 723.36 kg feddan(-1) at the end of the second year. Daily increments in weight per fish were 0.33 and 0.44 for first and second year, respectively. This experiment demonstrated the possibility of cultivation of eels as well as the higher growth rate in earthen ponds. The aquaculture strategy of eel with high stocking densities through low cost artificial feeds are recommended in future studies. PMID:19070049

  12. RNA/DNA ratios in American glass eels (Anguilla rostrata): evidence for latitudinal variation in physiological status and constraints to oceanic migration?

    PubMed

    Laflamme, Simon; Côté, Caroline; Gagnaire, Pierre-Alexandre; Castonguay, Martin; Bernatchez, Louis

    2012-05-01

    During their larval leptocephalus phase, newly hatched American eels undergo an extensive oceanic migration from the Sargasso Sea toward coastal and freshwater habitats. Their subsequent metamorphosis into glass eel is accompanied by drastic morphological and physiological changes preceding settlement over a wide geographic range. The main objective of this study was to compare RNA/DNA ratios and condition factor among glass eels in order to test the null hypothesis of no difference in physiological status and metabolic activity of glass eels at the outcome of their oceanic migration. This was achieved by analyzing glass eel samples collected at the mouth of 17 tributaries covering a latitudinal gradient across the species distribution range from Florida to Gaspésie (Québec). Our main observations were (i) a latitudinal increase in mean total length; (ii) a latitudinal variation in mean RNA/DNA ratios, which was best explained by a quadratic model reaching its minimum in the central range of sampling locations; and (iii) a latitudinal variation in Fulton's condition factor, which was best explained by a quadratic model reaching its maximum in the central range of sampling locations. Below we discuss the possible links between latitudinal variation in glass eel physiological status and variable energetic and environmental constraints to oceanic migration as a function of latitudinal distribution. PMID:22837833

  13. RNA/DNA ratios in American glass eels (Anguilla rostrata): evidence for latitudinal variation in physiological status and constraints to oceanic migration?

    PubMed Central

    Laflamme, Simon; Côté, Caroline; Gagnaire, Pierre-Alexandre; Castonguay, Martin; Bernatchez, Louis

    2012-01-01

    During their larval leptocephalus phase, newly hatched American eels undergo an extensive oceanic migration from the Sargasso Sea toward coastal and freshwater habitats. Their subsequent metamorphosis into glass eel is accompanied by drastic morphological and physiological changes preceding settlement over a wide geographic range. The main objective of this study was to compare RNA/DNA ratios and condition factor among glass eels in order to test the null hypothesis of no difference in physiological status and metabolic activity of glass eels at the outcome of their oceanic migration. This was achieved by analyzing glass eel samples collected at the mouth of 17 tributaries covering a latitudinal gradient across the species distribution range from Florida to Gaspésie (Québec). Our main observations were (i) a latitudinal increase in mean total length; (ii) a latitudinal variation in mean RNA/DNA ratios, which was best explained by a quadratic model reaching its minimum in the central range of sampling locations; and (iii) a latitudinal variation in Fulton's condition factor, which was best explained by a quadratic model reaching its maximum in the central range of sampling locations. Below we discuss the possible links between latitudinal variation in glass eel physiological status and variable energetic and environmental constraints to oceanic migration as a function of latitudinal distribution. PMID:22837833

  14. Temporal patterns of glass eel migration ( Anguilla anguilla L. 1758) in relation to environmental factors in the Western Greek inland waters

    NASA Astrophysics Data System (ADS)

    Zompola, Spyridoula; Katselis, George; Koutsikopoulos, Constantin; Cladas, Yannis

    2008-11-01

    Glass eel migration of the European eel Anguilla anguilla (L., 1758) in the eastern Mediterranean is poorly known despite the increasing state of anxiety for the future of the stock. In the present study, glass eel migration was investigated from October 1999 to April 2000, using experimental fishery with fyke nets, in two coastal systems along the western Greece (Ionian Sea): at the Sagiada marsh in the delta area of Kalamas River and at the mouth of Alfios River. The main period of the glass eel entrance was from December to March and the migration pattern was similar to those observed along the Atlantic coast of southwestern Europe. The variance of daily glass eel catches between the two studied sites was significantly different. The univariate and bivariate time series spectral analysis showed that glass eel short-term freshwater migration: (1) consisted of waves with periods from 5 to 40 days and (2) was correlated with environmental factors such as water temperature, atmospheric pressure, rainfall and moonlight. The observed differences between the two sites reveal the importance of the inland ecosystem characteristics.

  15. Characterization of Nb Superconducting Radio Frequency Cavities Based On In-Situ STEM And EELS

    NASA Astrophysics Data System (ADS)

    Tao, Runzhe

    Niobium, a 4d transition metal, has the highest superconducting transition temperature (Tc=9.2K) of any elemental superconductor as type II superconductor with coherent length, sigma approximately that of the penetration length, lambda. Pure niobium is grey in color and very soft, which makes this metal easily fabricable into different shapes for superconducting radio- frequency (SRF) cavities. Such cavities are used in some modern accelerators (SNS, CEBAF, XFEL), and are intended for usage in the next generation of particle accelerators, such as ILC. Since the crucial part of the cavities is top 100 nm of Nb near the inner cavity surface, considering the penetration depth is around 40 nm, it has attracted more and more attention in improving the surface process for optimizing the performance of the cavities. Nowadays, the main treatment of the Nb surface includes electro polishing (EP), buffered chemical polishing (BCP), high temperature baking (800 °C, 1000 °C and 1200 °C) and mild baking (120 °C). Firstly, the two half cells are welded together and the weld line is quite rough; there exists a lot of visible pits and defects on the inner shell of cavities. In this Ph.D. thesis, novel techniques in a scanning transmission electron microscope (STEM) that can be used to analyze the atomic scale structure-property relationship, both at room tem- perature and high/LN 2 temperature, are explored. Specifically, by using correlated Z-contrast imaging and electron energy loss spectrum (EELS), the structure, composition and bonding can be characterized directly on the atomic scale, also, light atoms, like H, O and C, are visible in ABF images. For the examining the defect behavior on the cavity surface, heating and cold stages are involved to simulate the baking treatment and low-temperature environments. These studies will serve as an important reference for qualifying different surface treatments to further improve SRF cavities' performance. The experimental results

  16. Cytotoxicity of silver dressings on diabetic fibroblasts.

    PubMed

    Zou, Shi-Bo; Yoon, Won-Young; Han, Seung-Kyu; Jeong, Seong-Ho; Cui, Zheng-Jun; Kim, Woo-Kyung

    2013-06-01

    A large number of silver-based dressings are commonly used in the management of chronic wounds that are at risk of infection, including diabetic foot ulcers. However, there are still controversies regarding the toxicity of silver dressings on wound healing. The purpose of this study was to objectively test the cytotoxicity of silver dressings on human diabetic fibroblasts. Human diabetic fibroblasts were obtained from the foot skin of four diabetic foot ulcer patients and cultured. The effect of five silver-containing dressing products (Aquacel Ag, Acticoat*Absorbent, Medifoam Ag, Biatain Ag and PolyMem Ag) and their comparable silver-free dressing products on morphology, proliferation and collagen synthesis of the cultured human diabetic fibroblasts were compared in vitro. In addition, extracts of each dressing were tested in order to examine the effect of other chemical components found in the dressings on cytotoxicity. The diabetic fibroblasts cultured with each silver-free dressing adopted the typical dendritic and fusiform shape. On the other hand, the diabetic fibroblasts did not adopt this typical morphology when treated with the different silver dressings. All silver dressings tested in the study reduced the viability of the diabetic fibroblasts and collagen synthesis by 54-70 and 48-68%, respectively, when compared to silver-free dressings. Silver dressings significantly changed the cell morphology and decreased cell proliferation and collagen synthesis of diabetic fibroblasts. Therefore, silver dressings should be used with caution when treating diabetic wounds. PMID:22533495

  17. Influence of injected silver content on synthesis of silver coated nickel particles by DC thermal plasma

    NASA Astrophysics Data System (ADS)

    Park, Si Taek; Kim, Tae-Hee; Park, Dong-Wha

    2016-06-01

    Silver nanoparticle-coated spherical nickel particles were prepared from a mixture of micro-sized silver and nickel as raw materials by DC thermal plasma treatment. The mixture of micro-sized silver and nickel powders was injected into the high-temperature region of an argon thermal plasma jet. Although the silver, with its very high thermal conductivity and relatively low boiling point, was thoroughly evaporated by this process, nickel was not evaporated perfectly because of its comparatively low thermal conductivity and high boiling point. The rough nickel powder was spheroidized as it melted. Finally, silver evaporated by the thermal plasma quickly condensed into nanoparticles on the surfaces of the micro-sized spherical nickel particles, aided by the sharp temperature gradient of the thermal plasma jet. With varying the ratios of silver to nickel feedstock from 1:10 to 5:1, the products synthesized in each condition were examined by XRD, XPS, FE-SEM, and FE-TEM. More silver nanoparticles were attached on the nickel by increasing the injected feedstock to 9.8 at% silver. Meanwhile, a decrease of silver in the products was observed when larger amounts of silver were introduced to the thermal plasma jet. The exposed silver components decreased with greater proportions of silver feedstock because of the metal's dendritic structure and the formation of silver-coated silver particles.

  18. Investigating the electronic structure of fluorite-structured oxide compounds: comparison of experimental EELS with first principles calculations

    SciTech Connect

    Aguiar, Jeff; Ramasse, Q. M.; Asta, Mark D.; Browning, Nigel D.

    2012-06-27

    Energy loss spectra from fluorite-structured ZrO2, CeO2, and UO2 compounds are compared with theoretical calculations based on density functional theory (DFT) and its extensions, including the use of Hubbard-U corrections (DFT + U) and hybrid functionals. Electron energy loss spectra (EELS) were obtained from each oxide using a scanning transmission electron microscope (STEM). The same spectra were computed within the framework of the full-potential linear augmented plane-wave (FLAPW) method. The theoretical and experimental EEL spectra are compared quantitatively using non-linear least squares peak fitting and a cross-correlation approach, with the best level of agreement between experiment and theory being obtained using the DFT + U and hybrid computational approaches.

  19. Introduced American eels Anguilla rostrata in European waters: life-history traits in a non-native environment.

    PubMed

    Marohn, L; Prigge, E; Hanel, R

    2014-06-01

    This study investigated growth, condition and development of American eels Anguilla rostrata that were introduced into a European river to estimate their competitive potential in a non-native habitat. Results demonstrate that A. rostrata develops normally in European waters and successfully competes with the native European eel Anguilla anguilla. In addition, A. rostrata appears to be more susceptible to the Asian swimbladder nematode Anguillicola crassus than A. anguilla and could support the further propagation of this parasite. Detected differences in fat content and gonad mass between Anguilla species are assumed to reflect species-specific adaptations to spawning migration distances. This study indicates that A. rostrata is a potential competitor for the native fauna in European fresh waters and suggests strict import regulations to prevent additional pressure on A. anguilla and a potential further deterioration of its stock situation. PMID:24787669

  20. Gold, Silver and Bronze Citations.

    ERIC Educational Resources Information Center

    American School & University, 2003

    2003-01-01

    Presents the gold, silver, and bronze winners of a competition, which judged the most outstanding learning environments at educational institutions nationwide. Jurors spent two days reviewing projects, focusing on concepts and ideas that made them exceptional. For each citation, the article offers information on the firm, client, total area, total…

  1. Genetic diversity in a morphologically conservative invasive taxon: Multiple introductions of swamp eels to the southeastern United States

    USGS Publications Warehouse

    Collins, T.M.; Trexler, J.C.; Nico, L.G.; Rawlings, T.A.

    2002-01-01

    Genetic analysis of introduced populations, especially in morphologically conservative taxa, can clarify introduction histories, identify management units and source populations, provide a more realistic estimate of the frequency of successful invasion, and suggest strategies for preventing further introductions. In the last 7 years, populations of swamp eels, referred to the Asian genus Monopterus (Family Synbranchidae) on the basis of external morphology, have been discovered in aquatic habitats near Atlanta, Georgia; Tampa, Florida; North Miami, Florida; and most recently in close proximity to Everglades National Park in Homestead, Florida. Swamp eels are large predators capable of dispersal over land and have the potential to disrupt already threatened ecosystems. We analyzed mitochondrial DNA sequences from four known populations in the continental United States and samples from Malaysia, Indonesia, Vietnam, and two locations in China to determine introduction histories, source populations, genetic diversity, and relationships among populations. Our results indicate that there have been at least three independent introductions of genetically distinct forms. Introduced populations in close proximity (separated by <40 km) are genetically distinct. The level of sequence difference among introduced populations reaches levels seen among sister families of teleost fishes for the same region of the mitochondrial genome. These genetically distinct introduced populations in all likelihood represent at least two and possibly three species. Regardless of species status, these genetically distinct lineages may be expected to vary in ecological or life-history traits, representing different potential threats to the ecosystems where they have been introduced. Given the success of swamp eels in invading many habitats around the world, further study of these eels is warranted to elucidate the characteristics of successful invaders and invasions.

  2. Characterization of PAMP/PRR interactions in European eel (Anguilla anguilla) macrophage-like primary cell cultures.

    PubMed

    Callol, A; Roher, N; Amaro, C; MacKenzie, S

    2013-10-01

    The eel (Anguilla anguilla) has been identified as a vulnerable species with stocks dramatically declining over the past decade. In an effort to support the species from overfishing of wild stocks increased interest in eel aquaculture has been notable. In order to expand the scarce knowledge concerning the biology of this species significant research efforts are required in several fields of biology. The development of cell culture systems to study the immune response is a key step towards an increased understanding of the immune response and to develop resources to support further study in this threatened species. Macrophages are one of the most important effector cells of the innate immune system. The capacity to engulf pathogens and orchestrate the immune response relies on the existence of different surface receptors, such as scavenger receptors and toll-like receptors. We have developed and described an eel macrophage-like in vitro model and studied its functional and transcriptomic responses. Macrophage-like cells from both head kidney and purified peripheral blood leukocytes were obtained and phagocytic activity measured for different whole bacteria and yeast. Moreover, based on PAMP-PRR association the innate immune response of both head kidney and PBL derived macrophage-like cells was evaluated against different pathogen-associated molecular patterns (PAMPs). Results highlight that peptidoglycan stimulation strongly induces inflammatory mRNA expression reflected in the up-regulation of pro-inflammatory genes IL1β and IL18 in PBL derived cells whereas IL8 is upregulated in head kidney derived cells. Furthermore TLR2 mRNA abundance is regulated by all stimuli supporting a multifunctional role for this pathogen recognition receptor (PRR) in eel macrophage-like cells. PMID:23911651

  3. Accumulation of metals, polycyclic (halogenated) aromatic hydrocarbons, and biocides in zebra mussel and eel from the Rhine and Meuse rivers

    SciTech Connect

    Hendriks, A.J.; Pieters, H.; Boer, J. de

    1998-10-01

    Concentrations of heavy metals and various groups of organic microcontaminants were measured in zebra mussel and eel from the Rhine-Meuse basin. Residues in mussel from the Rhine and Meuse were on average 2.3 and 2.9 times higher than in those from the reference location of IJsselmeer. Total body burdens of organic microcontaminants in mussel and eel varied between 0.05 to 0.07 mmol/kg fat weight in six out of seven samples. The largest contribution in mussels and eel came from polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), respectively. Concentrations of bromodiphenyl-ethers, chlorobenzenes, chloronitrobenzenes, chloroterphenyls, and chlorobenzyltoluenes were lower. Total polybrominated biphenyl residues appear lower than total PCB levels. The largest chlorobiocide residues were noted for 4,4{prime}-DDE, toxaphene, trichlorophenylmethane, and {gamma}-hexachlorocyclohexane. An extraordinary high body burden of 1.2 mmol/kg fat weight, largely consisting of acenaphthene, was observed in one sample. Ratios of concentrations in organism fat and dry organic suspended solids varied between 1 and 10 for traditionally monitored organochlorines, independent of the octanol-water partition coefficient. The values did not deviate significantly from a value of about 3.3, expected for equilibrium partitioning of persistent chemicals. Lower values were observed for PAHs and some chloro(nitro)benzenes. Most ratios of concentrations in eel and mussel fat were within the range of 1 to 10, also largely independent of K{sub ow}. Yet, values tended to be higher at K{sub ow} > 10{sup 6}. Ratios below 1 were noted for pentabromodiphenylether, pentachloro(thio)anisol, chlorobenzyltoluenes, and some chloronitrobenzenes, chlorobiphenyls, and chlorobiocides. These field data confirm recent modeling efforts on bioconcentration and biomagnification. For heavy metals, atomic mass explained 67% of the variation in zebra mussel residues.

  4. Involvement of drinking and intestinal sodium absorption in hyponatremic effect of atrial natriuretic peptide in seawater eels.

    PubMed

    Tsukada, Takehiro; Rankin, J Cliff; Takei, Yoshio

    2005-01-01

    Atrial natriuretic peptide (ANP) decreases plasma Na+ concentration and promtes seawater (SW) adaptation in eels. The hyponatremia may most probably be caused by increased branchial extrusion of Na+, but the mechanism has not been determined yet. The present study examined initially the effects of ANP on branchial Na+ efflux in vivo using isotopic 22Na. However, the efflux rate was not altered by infusion of a hyponatremic dose of ANP (5 pmol.kg(-1).min(-1)). Therefore, we sought to examine whether the ANP-mediated hyponatremia is caused by a decrease in the uptake of Na+ from the environment. Since a decrease in drinking was highly correlated with a degree of hyponatremia, conscious SW eels were infused with dilute SW into the stomach at a normal drinking rate to offset the antidipsogenic effect of ANP. Under this regimen, the hyponatremic effect of ANP was abolished. Then, we examined the site of Na+ absorption in the alimentary tract by measuring the changes in ion composition of intraluminal fluid along the tract. Since Na+ was absorbed at the esophagus and anterior/middle intestine, a sac was prepared at each site and the effects of ANP were examined in situ in conscious SW eels. ANP infusion did not alter Na+ absorption at the esophagus, but it profoundly reduced the absorption at the intestine. Together with our previous finding that ANP does not alter renal Na+ excretion, we propose that ANP reduces plasma Na+ concentration in SW eels by inhibiting drinking and subsequent absorption of Na+ by the intestine. PMID:15684587

  5. Seawater acclimation and inositol monophosphatase isoform expression in the European eel (Anguilla anguilla) and Nile tilapia (Orechromis niloticus).

    PubMed

    Kalujnaia, Svetlana; Gellatly, Steven A; Hazon, Neil; Villasenor, Alfredo; Yancey, Paul H; Cramb, Gordon

    2013-08-15

    Inositol monophosphatase (IMPA) is responsible for the synthesis of inositol, a polyol that can function as an intracellular osmolyte helping re-establish cell volume when exposed to hypertonic environments. Some epithelial tissues in euryhaline teleosts such as the eel and tilapia encounter considerable hyperosmotic challenge when fish move from freshwater (FW) to seawater (SW) environments; however, the roles played by organic osmolytes, such as inositol, have yet to be determined. Syntenic analysis has indicated that, as a result of whole genome- and tandem-duplication events, up to six IMPA isoforms can exist within teleost genomes. Four isoforms are homologs of the mammalian IMPA1 gene, and two isoforms are homologs of the mammalian IMPA2 gene. Although the tissue-dependent isoform expression profiles of the teleost isoforms appear to be species-specific, it was primarily mRNA for the IMPA1.1 isoform that was upregulated in epithelial tissues after fish were transferred to SW (up to 16-fold in eel and 90-fold in tilapia). Although up-regulation of IMPA1.1 expression was evident in many tissues in the eel, more substantial increases in IMPA1.1 expression were found in tilapia tissues, where SW acclimation resulted in up to 2,000-fold increases in protein expression, 16-fold increases in enzyme activity and 15-fold increases in tissue inositol contents. Immunohistochemical studies indicated that the tissue and cellular distribution of IMPA1.1 protein differed slightly between eels and tilapia; however, in both species the basal epithelial cell layers within the skin and fin, and the branchial epithelium and interstitial cells within the kidney, exhibited high levels of IMPA1.1 protein expression. PMID:23739342

  6. Quantitative parameters for the examination of InGaN QW multilayers by low-loss EELS.

    PubMed

    Eljarrat, Alberto; López-Conesa, Lluís; Magén, César; García-Lepetit, Noemí; Gačević, Žarko; Calleja, Enrique; Peiró, Francesca; Estradé, Sònia

    2016-08-17

    We present a detailed examination of a multiple InxGa1-xN quantum well (QW) structure for optoelectronic applications. The characterization is carried out using scanning transmission electron microscopy (STEM), combining high-angle annular dark field (HAADF) imaging and electron energy loss spectroscopy (EELS). Fluctuations in the QW thickness and composition are observed in atomic resolution images. The impact of these small changes on the electronic properties of the semiconductor material is measured through spatially localized low-loss EELS, obtaining band gap and plasmon energy values. Because of the small size of the InGaN QW layers additional effects hinder the analysis. Hence, additional parameters were explored, which can be assessed using the same EELS data and give further information. For instance, plasmon width was studied using a model-based fit approach to the plasmon peak; observing a broadening of this peak can be related to the chemical and structural inhomogeneity in the InGaN QW layers. Additionally, Kramers-Kronig analysis (KKA) was used to calculate the complex dielectric function (CDF) from the EELS spectrum images (SIs). After this analysis, the electron effective mass and the sample absolute thickness were obtained, and an alternative method for the assessment of plasmon energy was demonstrated. Also after KKA, the normalization of the energy-loss spectrum allows us to analyze the Ga 3d transition, which provides additional chemical information at great spatial resolution. Each one of these methods is presented in this work together with a critical discussion of their advantages and drawbacks. PMID:27499340

  7. Plasmonic characterization of photo-induced silver nanoparticles extracted from silver halide based TEM film

    NASA Astrophysics Data System (ADS)

    Sudheer, Tiwari, P.; Varshney, G. K.; Rai, V. N.; Srivastava, A. K.

    2016-05-01

    The plasmonic responses of silver nanoparticles extracted from silver halide based electron microscope film are investigated. Photo-reduction process is carried out to convert the silver halide grains into the metallic silver. The centrifuge technique is used for separating the silver nanoparticles from the residual solution. Morphological study performed by field emission scanning electron microscope (FESEM) shows that all the nanoparticles have an average diameter of ~120 nm with a high degree of mono dispersion in size. The localized surface plasmon resonance (LSPR) absorption peak at ~537 nm confirms the presence of large size silver nanoparticles.

  8. Differential timing of gene expression regulation between leptocephali of the two Anguilla eel species in the Sargasso Sea.

    PubMed

    Bernatchez, Louis; St-Cyr, Jérôme; Normandeau, Eric; Maes, Gregory E; Als, Thomas D; Kalujnaia, Svetlana; Cramb, Gordon; Castonguay, Martin; Hansen, Michael M

    2011-12-01

    The unique life-history characteristics of North Atlantic catadromous eels have long intrigued evolutionary biologists, especially with respect to mechanisms that could explain their persistence as two ecologically very similar but reproductively and geographically distinct species. Differential developmental schedules during young larval stages have commonly been hypothesized to represent such a key mechanism. We performed a comparative analysis of gene expression by means of microarray experiments with American and European eel leptocephali collected in the Sargasso Sea in order to test the alternative hypotheses of (1) differential timing of gene expression regulation during early development versus (2) species-specific differences in expression of particular genes. Our results provide much stronger support for the former hypothesis since no gene showed consistent significant differences in expression levels between the two species. In contrast, 146 genes showed differential timings of expression between species, although the observed expression level differences between the species were generally small. Consequently, species-specific gene expression regulation seems to play a minor role in species differentiation. Overall, these results show that the basis of the early developmental divergence between the American and European eel is probably influenced by differences in the timing of gene expression regulation for genes involved in a large array of biological functions. PMID:22393514

  9. A physiologically based toxicokinetic (PBTK) model for moderately hydrophobic organic chemicals in the European eel (Anguilla anguilla).

    PubMed

    Brinkmann, Markus; Freese, Marko; Pohlmann, Jan-Dag; Kammann, Ulrike; Preuss, Thomas G; Buchinger, Sebastian; Reifferscheid, Georg; Beiermeister, Anne; Hanel, Reinhold; Hollert, Henner

    2015-12-01

    The European eel (Anguilla anguilla) is a facultatively catadromous fish species with a complex life cycle. Its current population status is alarming: recruitment has decreased drastically since the 1980s and its stock is still considered to be outside safe biological limits. Although there is no consensus on the reasons for this situation, it is currently thought to have resulted from a combination of different stressors, including anthropogenic contaminants. To deepen our understanding of the processes leading to the accumulation of lipophilic organic contaminants in yellow eels (i.e. the feeding, continental growth stage), we developed a physiologically based toxicokinetic model using our own data and values from the literature. Such models can predict the uptake and distribution of water-borne organic chemicals in the whole fish and in different tissues at any time during exposure. The predictive power of the model was tested against experimental data for six chemicals with n-octanol-water partitioning coefficient (log Kow) values ranging from 2.13-4.29. Model performance was excellent, with a root mean squared error of 0.28 log units. This model has the potential to help identify suitable habitats for restocking under eel management plans. PMID:26218567

  10. Effect of photoperiod on endocrine profiles and vitellogenin expression in European eels Anguilla anguilla during artificially induced ovarian development.

    PubMed

    Parmeggiani, A; Govoni, N; Zannoni, A; Di Biase, A; Sirri, R; Forni, M; Mandelli, M; Mordenti, O

    2015-03-01

    The aim of this work was to determine the effects of dark and light conditions on the E2, testosterone and thyroid hormones levels and on the gene expression levels (vitellogenin 1, vitellogenin 2, and estradiol receptor one) in European eels (Anguilla anguilla) during ovarian development induced by increasing doses of carp pituitary extracts (CPEs). The subjects were divided into 2 groups: 14-hour light:10-hour dark (Light Group) and 24-hour darkness (Dark Group). All the eels received intramuscular injections with CPE at a dosage of 10 mg/kg body weight (BW) once a week for the first 3 weeks, 20 mg/kg BW fourth-sixth week, 30 mg/kg BW seventh-ninth week, and 40 mg/kg up to the end of the experiment (13th week). Vitellogenin and estradiol receptor expression levels did not show significant differences between the two housing conditions whereas in both groups vitellogenin mRNA increased starting from first CPE injection. Testosterone and 17-beta estradiol plasma levels were significantly greater in the Dark Group compared with the Light Group starting from the ninth and the 13th week, respectively. These results suggest that darkness could be a useful variable for standardizing gonadal maturation in eels kept in captivity. PMID:25459031

  11. Purification and characterization of a novel imidazole dipeptide synthase from the muscle of the Japanese eel Anguilla japonica.

    PubMed

    Tsubone, Shiori; Yoshikawa, Naoko; Okada, Shigeru; Abe, Hiroki

    2007-04-01

    We have purified a novel enzyme from eel white muscle which catalyzes the syntheses of imidazole dipeptides, such as carnosine (beta-alanyl-L-histidine), anserine (beta-alanyl-pi-methyl-L-histidine), and balenine (ophidine; beta-alanyl-tau-methyl-L-histidine), directly from their precursors. The enzyme was purified 1130-fold from eel muscle by a series of column chromatographies. Although eel muscle contains a large amount of carnosine and only trace amounts of anserine and balenine, the anserine synthesizing activity was by far the highest. From gel permeation chromatography, the molecular mass of the enzyme was calculated to be 275kDa. SDS-PAGE of the purified enzyme represented a band around 43kDa, suggesting that the native enzyme is a hexamer or heptamer. The optimal pH and temperature were around 9.5 and 60 degrees C, respectively. K(m) values for beta-alanine and pi-methyl-L-histidine were 44 and 89mM, respectively. The enzyme was greatly activated by Zn(2+) and inhibited by EDTA. The N-terminal amino acid sequence of 25 residues of the purified enzyme showed 52% amino acid identity to 38-62 residues of zebrafish haptoglobin precursor. The purified enzyme also exhibited hydrolytic activity against these imidazole dipeptides. PMID:17261377

  12. Effects of sea water and stanniectomy on branchial Ca(2+) handling and drinking rate in eel (Anguilla anguilla L.).

    PubMed

    van der Heijden AJ; Verbost; Bijvelds; Atsma; Wendelaar Bonga SE; Flik

    1999-01-01

    We examined the effects of seawater adaptation and extirpation of the Stannius corpuscles on branchial Ca(2+) flows, gill plasma membrane Ca(2+) transporters and drinking rate of European eels, Anguilla anguilla. Transepithelial Ca(2+) inflow in the gills increased 2 weeks after transfer of the eels from fresh water to sea water and after stanniectomy. Neither of these treatments changed the membrane density or the affinity of the Ca(2+)-extrusion mechanisms (Ca(2+)-ATPase and Na(+)/Ca(2+)-exchanger) in the gill cells, as measured in basolateral plasma membrane vesicles. We conclude that the increase in the Ca(2+)-transporting capacity observed in the gills of fish exposed to the larger transepithelial Ca(2+) fluxes, resulting from exposure to sea water or stanniectomy, involves an increase in number and/or size of the Ca(2+)-transporting cells, but not in the membrane density of Ca(2+) transporters. Branchial Ca(2+) outflow was higher in stanniectomised than in sham-operated fish. Changes in electrochemical driving forces as well as plasma stanniocalcin or teleocalcin levels may be the basis for the observed differences. Stanniectomy enhanced drinking in stanniectomised eels. Drinking was not further affected by transfer to sea water. These observations suggest that the corpuscles of Stannius are involved in the water balance. PMID:10460737

  13. Antimicrobial Properties of a Novel Silver-Silica Nanocomposite Material▿

    PubMed Central

    Egger, Salome; Lehmann, Rainer P.; Height, Murray J.; Loessner, Martin J.; Schuppler, Markus

    2009-01-01

    Nanotechnology enables development and production of novel silver-based composite materials. We used in vitro tests to demonstrate the antimicrobial activity of a silver-silica nanocomposite compared to the activities of conventional materials, such as silver nitrate and silver zeolite. A silver-silica-containing polystyrene material was manufactured and shown to possess strong antimicrobial properties. PMID:19270121

  14. Effect of nano silver and silver nitrate on seed yield of (Ocimum basilicum L.)

    PubMed Central

    2014-01-01

    Background The aim of this study was to evaluate the effect of nano silver and silver nitrate on yield of seed in basil plant. The study was carried out in a randomized block design with three replications. Results Four levels of either silver nitrate (0, 100, 200 and 300 ppm) or nano silver (0, 20, 40, and 60 ppm) were sprayed on basil plant at seed growth stage. The results showed that there was no significant difference between 100 ppm of silver nitrate and 60 ppm concentration of nano silver on the shoot silver concentration. However, increasing the concentration of silver nitrate from 100 to 300 ppm caused a decrease in seed yield. In contrast, a raise in the concentration of nano silver from 20 to 60 ppm has led to an improvement in the seed yield. Additionally, the lowest amount of seed yield was found with control plants. Conclusions Finally, with increasing level of silver nitrate, the polyphenol compound content was raised but the enhancing level of nano silver resulting in the reduction of these components. In conclusion, nano silver can be used instead of other compounds of silver. PMID:25383311

  15. Immunogold silver staining for light microscopy.

    PubMed

    Lackie, P M

    1996-07-01

    The immunogold silver staining method (IGSS) is widely used as a sensitive and specific immunohistochemical visualisation technique. IGSS involves the specific deposition of metallic silver at the site of immunogold labelling and provides a means of visualisation at low magnification by light or electron microscopy. Silver developers for IGSS rapidly deposit metallic silver only at the site of heavy metals, including gold and silver, because of their catalytic activity. The developing solution contains the silver ions and reducing agent necessary for this reaction. Using different silver salts as ion donors and by selecting an appropriate temperature and pH, visible amounts of silver can be deposited in a few minutes at the site of colloidal gold labelling while little non-specific background deposition occurs. Inclusion of protective colloids in the solution can also be used to control the reaction. Although studies of the chemical basis of silver deposition around unlabelled colloidal gold date back to 1939, immunogold enhancement by silver was established in 1983. The IGSS method evolved from the combination of disparate photographic, histochemical and immunogold techniques which have been effectively combined and optimised over the last 10 years to provide a visualisation system which is well suited to many immunohistochemical studies. PMID:8858363

  16. Contemporary anthropogenic silver cycle: a multilevel analysis.

    PubMed

    Johnson, Jeremiah; Jirikowic, Julie; Bertram, Marlen; van Beers, D; Gordon, R B; Henderson, Kathryn; Klee, R J; Lanzano, Ted; Lifset, R; Oetjen, Lucia; Graedel, T E

    2005-06-15

    Anthropogenic cycling of silver in 1997 is presented using three discrete governmental units: 64 countries encompassing what we believe to be over 90% of global silver flows, 9 world regions, and the entire planet. Using material flow analysis (MFA) techniques, the country level cycles are aggregated to produce the regional cycles, which are used to form a "best estimate" global cycle. Interesting findings include the following: (1) several silver-mining countries export ore and concentrate but also import silver-containing semiproducts and products; (2) the level of development for a country, as indicated by the gross domestic product, is a fair indicator of silver use, but several significant outliers exist; (3) the countries with the greatest mine production include Mexico, the United States, Peru, and China, whereas the United States, Japan, India, Germany, and Italy lead in the fabrication and manufacture of products; (4) North America and Europe's use of silver products exceed that of other regions on a per capita basis; (5) global silver discards, including tailings and separation waste, totaled approximately 57% of the silver mined; (6) approximately 57% of the silver entering waste management globally is recycled; and (7) the amount of silver entering landfills globally is comparable to the amount found in tailings. The results of this MFA lay the basis for further analysis, which in turn can offer insight into natural resource policy, the characterization of environmental impact, and better resource management. PMID:16047806

  17. Effect of the probiotic Lactobacillus rhamnosus on the expression of genes involved in European eel spermatogenesis.

    PubMed

    Vílchez, M Carmen; Santangeli, Stefania; Maradonna, Francesca; Gioacchini, Giorgia; Verdenelli, Cristina; Gallego, Victor; Peñaranda, David S; Tveiten, Helge; Pérez, Luz; Carnevali, Oliana; Asturiano, Juan F

    2015-11-01

    Positive effects of probiotics on fish reproduction have been reported in several species. In the present study, 40 male European eels were weekly treated with recombinant hCG for 9 weeks and with three different concentrations (10(3), 10(5), and 10(6) CFU/mL) of probiotic Lactobacillus rhamnosus IMC 501 (Sinbyotec, Italy). The probiotics were daily added to the water from the sixth week of the hCG treatment. Males from the treated and control groups were sacrificed after 1, 2, and 3 weeks of probiotic treatment (seventh-ninth weeks of hCG treatment); at this point, sperm and testis samples were also collected. Sperm volume was estimated, and motility was analyzed by computer-assisted sperm analysis software. Alternations in transcription of specific genes involved in reproductive process such as activin, androgen receptors α and β (arα and arβ), progesterone receptor 1 (pr1), bone morphogenetic protein 15 (bmp15), and FSH receptor (fshr) were analyzed in the testis. After 2 weeks of probiotic treatment, sperm production and sperm motility parameters (percentage of motile cells and percentage of straight-swimming spermatozoa) were increased in the European eel treated with 10(5) CFU/mL compared to controls or to the other probiotic doses. These changes were associated with increases in messenger RNA expression of activin, arα, arβ, pr1, and fshr. Conversely, after 3 weeks, activin and pr1 expression decreased. No significant changes were observed on bmp15 expression throughout the duration of the treatment with 10(5) CFU/mL dose. The lowest and highest probiotic dose (10(3) and 10(6) CFU/mL, respectively) inhibited the transcription of all genes along all the experiment, except for arα and arβ after 1 week of probiotic treatment when compared to controls. The changes observed by transcriptomic analysis and the sperm parameters suggest that a treatment with L rhamnosus at 10(5) CFU/mL for 2 weeks could improve spermatogenesis process in Anguilla

  18. Probing Subsurface and Stream Particle Composition Through Optical Analysis at the Eel River Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Nghiem, A.; Thurnhoffer, B. M.; Bishop, J. K. B.; Kim, H.

    2014-12-01

    Particles constitute a significant portion of the flux weathered material from continents to ocean basins but little is understood about their seasonal dynamics particularly in subsurface and headwater stream environments. At the Eel River Critical Zone Observatory, located near the headwaters of the South Fork Eel River in the Angelo Coast Range Reserve (Northern California), groundwater from weathered bedrock and stream waters are sampled at a frequency of one to three days from three wells (Well 1 down-slope, Well 3 mid-slope, Well 10 upper-slope) and Elder Creek. Approximately one thousand samples collected by automated ISCO Gravity Filtration System (GFS; Kim et al. 2012, EST) since 2011 have been filtered through 0.45 μm 25 mm diameter Supor filters. Filters imaged under controlled lighting are analyzed for red, green, and blue optical density (OD) to enable rapid assessment of sample loading and color as a prelude to and selection aid for more labor-intensive ICP-MS and Scanning Electron Microscopic analysis. For example, samples with lower red OD relative to green and blue may correspond to samples high in Mn/Fe oxides. Optical imaging of the loaded filters provides a time-series over three years and color anomalies in these filters along with chemical analysis of dissolved and particulate filtrate is used to establish a method for calibrating optical data to interpret chemical composition of water and particles. Results are interpreted within a framework of environmental data such as rainfall, stream discharge and turbidity, and water table depth measured at the heavily monitored forested hillslope. Data from the four locations range up to 0.6 OD units with a typical detection limit of better than 0.01 OD units. At Well 10, wet season filter samples exhibit highest particle loading (OD ~ 0.3) with values rapidly decreasing during the dry season (OD < D.L.) water table recession. At Well 1, particle loads instantaneously reflect intense rain events

  19. Debris Flow Control on Fluvial Hanging Valley Formation in the South Fork Eel River, CA

    NASA Astrophysics Data System (ADS)

    Deshpande, N.; Perkins, J.; Finnegan, N. J.

    2012-12-01

    An understanding of how base level signals are transmitted into landscapes is fundamental to interpreting river long profiles in tectonically active settings. Fluvial hanging valleys, locations where waves of incision have apparently arrested at tributary junctions, suggest that base level propagation is an unsteady process in many settings. A recent hypothesis (Wobus et al., 2006) explains the formation of fluvial hanging valleys via an instability in the saltation abrasion model of Sklar and Dietrich (2004). At locations where small steep tributaries join trunk streams, tributary incision rates can actually decrease with increasing channel slope when subjected to downstream base-level fall. However, we note that in mountainous river networks steep tributaries also commonly convey debris flows into trunk channels. Since these tributary junctions mark the upstream limit of channels whose beds are mobilized on a regular basis during flood events, here we hypothesize that transitions from fluvial to debris flow channels control the location of fluvial hanging valleys. To test our hypothesis, we exploit a natural experiment in base level fall and landscape evolution along the South Fork Eel River, which is argued to be responding to an increase in rock uplift rate associated with the passage of the Mendocino Triple Junction. In order to separate debris flow channels from fluvial channels, we use airborne laser swath mapping (ALSM) to quantify channel slopes and concavities. In our analysis, concavity data are noisy and represent a poor metric for determination of debris flow channels. In lieu of this, we choose a more straightforward metric of channel slope to discriminate where debris flows occur on the landscape. We find that, on average, fluvial hanging valleys are only present in tributaries with average gradients above 0.10, consistent with empirical determinations of the gradient at which debris flow channels transition to fluvial channels (0.03-0.10). Field

  20. Regional variability of slope stability: Application to the Eel margin, California

    USGS Publications Warehouse

    Lee, H.; Locat, J.; Dartnell, P.; Israel, K.; Florence, Wong

    1999-01-01

    Relative values of downslope driving forces and sediment resisting forces determine the locations of submarine slope failures. Both of these vary regionally, and their impact can be addressed when the data are organized in a Geographic Information System (GIS). The study area on the continental margin near the Eel River provides an excellent opportunity to apply GIS spatial analysis techniques for evaluation of slope stability. In this area, swath bathymetric mapping shows seafloor morphology and distribution of slope steepness in fine detail, and sediment analysis of over 70 box cores delineates the variability of sediment density near the seafloor surface. Based on the results of ten geotechnical studies of submarine study areas, we developed an algorithm that relates surface sediment density to the shear strength appropriate to the type of cyclic loading produced by an earthquake. Strength and stress normalization procedures provide results that are conceptually independent of subbottom depth. Results at depth are rigorously applicable if sediment lithology does not vary significantly and consolidation state can be estimated. Otherwise, the method applies only to shallow-seated slope failure. Regional density, slope, and level of anticipated seismic shaking information were combined in a GIS framework to yield a map that illustrates the relative stability of slopes in the face of seismically induced failure. When a measure of predicted relative slope stability is draped on an oblique view of swath bathymetry, a variation in this slope stability is observed on an otherwise smooth slope along the mid-slope region north of a plunging anticline. The section of slope containing diffuse, pockmarked gullies has a lower measure of stability than a separate section containing gullies that have sharper boundaries and somewhat steeper sides. Such an association suggests that our slope-stability analysis relates to the stability of the gully sides. The remainder of the

  1. Optical properties of Group X-XII intermetallic compounds studied by HR-EELS.

    PubMed

    Sato, Yohei; Terauchi, Masami; Kameoka, Satoshi; Tsai, An-Pang

    2014-11-01

    Electronic structure of d orbital states in transition metals is a key factor for their physical properties and chemical functions. Copper and intermetallic compound PdZn have good catalysis function for the methanol steam reforming reaction. Tsai et al. showed that from results of XPS measurements the d electronic structure of PdZn was similar with that of copper, and the catalysis function should be related to the d electron states [1]. This similarity of d electronic states leads to another view point of the mechanism for coloring the intermetallic compounds. It is well-known that the characteristic red color of copper is caused by interband transition from the d electrons. Therefore, PdZn and Group X-XII intermetallic compounds are expected to be colored and the optical properties should depend on the d electronic states. In this study, the relations between optical properties and d electron states of Group X-XII intermetallic compounds were investigated by using high energy-resolution electron energy-loss spectroscopy (HR-EELS) based on transmission electron microscopy (TEM). From the relation between optical properties and d electronic states, the mechanism of colored intermetallic compounds will be discussed.Figure shows the optical reflectivity of NiZn, PdZn and PtZn, which were derived from EELS spectra by Kramers-Kronig analysis. Intensity drops (arrows) of the reflectivity were observed in visible energy region. These are caused by the interband transitions from d electronic states. The energy positions of the reflectivity drops have tendency of shifting to higher energy side with increasing atomic number of Group X elements (Ni → Pd → Pt). This indicates that the transition energies of d electrons become larger with the atomic number of the elements. First principle calculations (WIEN2k) confirmed that the interband transitions of d electronic states were excitations from bonding d states to hybrid states of anti-bonding s, p, and d states of Group

  2. Lipid increases in European eel (Anguilla anguilla) in Scotland 1986-2008: an assessment of physical parameters and the influence of organic pollutants.

    PubMed

    Oliver, Ian W; Macgregor, Kenneth; Godfrey, Jason D; Harris, Lynsay; Duguid, Alistair

    2015-05-01

    Recruitment of the European eel (Anguilla anguilla) has fallen steadily in recent decades, with current levels understood to be at around 5% of those in the 1970s, and the species is now widely recognised as being endangered. Changes in ocean currents, climate shifts, habitat loss, overfishing, barriers to migration, increased predation, plastic litter and exposure to chemicals have all been postulated as potential causative factors. Several studies have shown a general decline in eel quality (lower lipid content and body condition) over time that may be linked to reduced reproductive success. In this study, data from an eel sampling campaign in 1987 are compared with recent data (2004-2008) for eels in Scotland to assess any temporal changes in eel quality indicators and also to assess any links between current levels of chemical exposure and eel quality. Mean lipid levels, as a percentage of wet muscle mass, were higher in 2004-2008 (37 ± 1.9% SE) than in 1986 (21 ± 0.9% SE). By contrast, mean body condition index (K) was slightly lower in the latter period. Considering the 2004-2008 samples, significant inter-site variation was observed for condition index K, while intra-site variation was observed for lipid content and physical parameters relative to age (i.e. mass/age, length/age and lipid/age ratios); however, the variations observed could not be linked to differences in chemical body burdens, indicating that no chemical impacts on the parameters assessed are discernible during the continental life stage of eels in Scotland. PMID:25651809

  3. Toxicogenomic responses of nanotoxicity in Daphnia magna exposed to silver nitrate and coated silver nanoparticles

    EPA Science Inventory

    Applications for silver nanomaterials in consumer products are rapidly expanding, creating an urgent need for toxicological examination of the exposure potential and ecological effects of silver nanoparticles (AgNPs). The integration of genomic techniques into environmental toxic...

  4. Silver ions eluted from partially protected silver nanoparticles.

    PubMed

    Heidari Zare, Hamideh; Düttmann, Oliver; Vass, Attila; Franz, Gerhard; Jocham, Dieter

    2016-01-01

    The most prominent character of a new type of antibacterial urological catheters is the zebra-stripe pattern of a silver film, which is plated electroless on their interior wall and capped by a very thin semipermeable layer of parylene. This design effectively controls the release rate of Ag(+) ions in artificial urine, which has been measured as function of time with optical emission spectroscopy. By evaluating the minimum inhibitory concentration against certain strains of bacteria with solutions of AgNO3 of known concentration with the method of optical density and applying this analysis to the silver-eluting catheters, it was shown that this moderation prolongs the period of their application significantly. But to act as antibacterial agent in chlorine-containing solutions, as in urine, the presence of urea is required to avoid precipitation of AgCl and to meet or even exceed the minimum inhibitory concentration of Ag(+). The quality of the silver depot layer was further determined by the deposition rate and its morphology, which revealed that the film consisted of grains with a mean size of 150 nm. PMID:27400747

  5. Aquatic Toxicity Comparison of Silver Nanoparticles and Silver Nanowires

    PubMed Central

    Kim, Tae Gyu; Kim, Jin Kwon; Kim, Ellen; Lee, Ji Hyun; Chung, Young Shin

    2015-01-01

    To better understand the potential ecotoxicological impact of silver nanoparticles (AgNPs) and silver nanowires (AgNWs) released into freshwater environments, the toxicities of these nanomaterials were assessed and compared using Organization for Economic Cooperation and Development (OECD) test guidelines, including a “Daphnia sp., acute immobilization test,” “Fish, acute toxicity test,” and “freshwater alga and cyanobacteria, growth inhibition test.” Based on the estimated median lethal/effective concentrations of AgNPs and AgNWs, the susceptibility to the nanomaterials was different among test organisms (daphnia > algae > fish), suggesting that the AgNPs are classified as “category acute 1” for Daphnia magna, “category acute 2” for Oryzias latipes, and “category acute 1” for Raphidocelis subcapitata, while the AgNWs are classified as “category acute 1” for Daphnia magna, “category acute 2” for Oryzias latipes, and “category acute 2” for Raphidocelis subcapitata, according to the GHS (Globally Harmonized System of Classification and Labelling of Chemicals). In conclusion, the present results suggest that more attention should be paid to prevent the accidental or intentional release of silver nanomaterials into freshwater aquatic environments. PMID:26125025

  6. Application of Silver and Silver Oxide Nanoparticles Impregnated on Activated Carbon to the Degradation of Bromate.

    PubMed

    Choi, J S; Lee, H; Park, Y K; Kim, S J; Kim, B J; An, K H; Kim, B H; Jung, S C

    2016-05-01

    Silver and silver oxide nanoparticles were impregnated on the surface of powdered activated carbon (PAC) using a single-step liquid phase plasma (LPP) method. Spherical silver and silver oxide nanoparticles of 20 to 100 nm size were dipersed evenly on the surface of PAC. The impregnated PAC exhibited a higher activity for the decomposition of bromate than bare PAC. The XPS, Raman and EDX analyses showed that the Ag/PAC composites synthesized by the LPP process. PMID:27483780

  7. Electrodeposited Silver Nanoparticles Patterned Hexagonally for SERS

    SciTech Connect

    Gu, Geun Hoi; Lee, Sue Yeone; Suh, Jung Sang

    2010-08-06

    We have fabricated hexagonally patterned silver nanoparticles for surface-enhanced Raman scattering (SERS) by electrodepositing silver on the surface of an aluminum plate prepared by completely removing the oxide from anodic aluminum oxide (AAO) templates. Even after completely removing the oxide, well-ordered hexagonal patterns, similar to the shape of graphene, remained on the surface of the aluminum plate. The borders of the hexagonal pattern protruded up to form sorts of nano-mountains at both the sides and apexes of the hexagon, with the apexes protruding even more significantly than the sides. The aluminum plate prepared by completely removing the oxide has been used in the preparation of SERS substrates by sputter-coating of gold or silver on it. Instead of sputter-coating, here we have electro-deposited silver on the aluminum plate. When silver was electro-deposited on the plate, silver nanoparticles were made along the hexagonal margins.

  8. Passive particle dosimetry. [silver halide crystal growth

    NASA Technical Reports Server (NTRS)

    Childs, C. B.

    1977-01-01

    Present methods of dosimetry are reviewed with emphasis on the processes using silver chloride crystals for ionizing particle dosimetry. Differences between the ability of various crystals to record ionizing particle paths are directly related to impurities in the range of a few ppm (parts per million). To understand the roles of these impurities in the process, a method for consistent production of high purity silver chloride, and silver bromide was developed which yields silver halides with detectable impurity content less than 1 ppm. This high purity silver chloride was used in growing crystals with controlled doping. Crystals were grown by both the Czochalski method and the Bridgman method, and the Bridgman grown crystals were used for the experiments discussed. The distribution coefficients of ten divalent cations were determined for the Bridgman crystals. The best dosimeters were made with silver chloride crystals containing 5 to 10 ppm of lead; other impurities tested did not produce proper dosimeters.

  9. Preparation of silver nanoparticles at low temperature

    NASA Astrophysics Data System (ADS)

    Mishra, Mini; Chauhan, Pratima

    2016-04-01

    Silver from ancient time is used as antimicrobial agent in the bulk form but now with the advancement in nanotechnology silver in the form of nanoparticles shown potential effect against microbes which make us easy to fight with many diseases plants and animals. In this work silver nanoparticles were synthesized by chemical routes using sodium borohydride as reducing agent at low temperature. The particles were characterized through UV-Visible spectroscopy as well as X-Ray Diffraction. The UV-visible spectra of silver nanoparticles exhibited absorption at 425 cm; the crystallite size of the particles is between 19nm to 39nm. EDAX graph shows two peaks of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.

  10. Silver nanocluster catalytic microreactors for water purification

    NASA Astrophysics Data System (ADS)

    Da Silva, B.; Habibi, M.; Ognier, S.; Schelcher, G.; Mostafavi-Amjad, J.; Khalesifard, H. R. M.; Tatoulian, M.; Bonn, D.

    2016-07-01

    A new method for the elaboration of a novel type of catalytic microsystem with a high specific area catalyst is developed. A silver nanocluster catalytic microreactor was elaborated by doping a soda-lime glass with a silver salt. By applying a high power laser beam to the glass, silver nanoclusters are obtained at one of the surfaces which were characterized by BET measurements and AFM. A microfluidic chip was obtained by sealing the silver coated glass with a NOA 81 microchannel. The catalytic activity of the silver nanoclusters was then tested for the efficiency of water purification by using catalytic ozonation to oxidize an organic pollutant. The silver nanoclusters were found to be very stable in the microreactor and efficiently oxidized the pollutant, in spite of the very short residence times in the microchannel. This opens the way to study catalytic reactions in microchannels without the need of introducing the catalyst as a powder or manufacturing complex packed bed microreactors.

  11. Production of Recovery of Silver for Laboratory Use.

    ERIC Educational Resources Information Center

    Hill, James W.; Bellows, Lena

    1986-01-01

    Describes a method by which teachers can either produce their own silver of "technical" quality or recycle silver chloride residues to recover the silver for similar reuse. Procedures used are outlined and economics of the method are discussed. (JN)

  12. Preparation of silver-activated zinc sulfide thin films

    NASA Technical Reports Server (NTRS)

    Feldman, C.; Swindells, F. E.

    1968-01-01

    Silver improves luminescence and reduces contamination of zinc sulfide phosphors. The silver is added after the zinc sulfide phosphors are deposited in thin films by vapor evaporation, but before calcining, by immersion in a solution of silver salt.

  13. Effects of water hardness on size and hatching success of silver carp eggs

    USGS Publications Warehouse

    Rach, Jeff J.; Sass, Greg G.; Luoma, James A.; Gaikowski, Mark P.

    2010-01-01

    Eggs of silver carp Hypophthalmichthys molitrix absorb water after release from the female, causing them to become turgid and to increase substantially in size. The volume of water that diffuses within an egg is most likely determined by (1) the difference in ionic concentration between the egg and the water that surrounds it and (2) the elasticity of the egg membrane. Prior observations suggest that silver carp eggs may swell and burst in soft waters. If water hardness affects silver carp reproductive success in nonnative ecosystems, this abiotic factor could limit silver carp distribution or abundance. In this study, we tested the effect of water hardness on silver carp egg enlargement and hatching success. Groups of newly fertilized silver carp eggs were placed in water at one of five nominal water hardness levels (50, 100, 150, 200, or 250 mg/L as CaCO3) for 1 h to harden (absorb water after fertilization). Egg groups were then placed in separate incubation vessels housed in two recirculation systems that were supplied with either soft (50 mg/L as CaCO3) or hard (250 mg/L as CaCO3) water to evaluate hatching success. Tests were terminated within 24 h after viable eggs had hatched. Eggs that were initially placed in 50-mg/L water to harden were larger (i.e., swelled more) and had a greater probability of hatch than eggs hardened in other water hardness levels. Unlike the effect of water hardness during egg hardening, the water hardness during incubation appeared to have no effect on egg hatching success. Our research suggests that water hardness may not be a limiting factor in the reproduction, recruitment, and range expansion of silver carp in North America.

  14. In Situ STEM-EELS observation of nanoscale interfacial phenomena in all-solid-state batteries

    DOE PAGESBeta

    Wang, Ziying; Xin, Huolin L.; Santhanagopalan, Dhamodaran; Zhang, Wei; Wang, Feng; He, Kai; Li, Juchuan; Dudney, Nancy; Meng, Ying Shirley

    2016-05-03

    Behaviors of functional interfaces are crucial factors in the performance and safety of energy storage and conversion devices. Indeed, solid electrode–solid electrolyte interfacial impedance is now considered the main limiting factor in all-solid-state batteries rather than low ionic conductivity of the solid electrolyte. Here, we present a new approach to conducting in situ scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) in order to uncover the unique interfacial phenomena related to lithium ion transport and its corresponding charge transfer. Our approach allowed quantitative spectroscopic characterization of a galvanostatically biased electrochemical system under in situ conditions. Usingmore » a LiCoO2/LiPON/Si thin film battery, an unexpected structurally disordered interfacial layer between LiCoO2 cathode and LiPON electrolyte was discovered to be inherent to this interface without cycling. During in situ charging, spectroscopic characterization revealed that this interfacial layer evolved to form highly oxidized Co ions species along with lithium oxide and lithium peroxide species. Here, these findings suggest that the mechanism of interfacial impedance at the LiCoO2/LiPON interface is caused by chemical changes rather than space charge effects. Insights gained from this technique will shed light on important challenges of interfaces in all-solid-state energy storage and conversion systems and facilitate improved engineering of devices operated far from equilibrium.« less

  15. Kinematics of terrestrial capture of prey by the eel-catfish Channallabes apus.

    PubMed

    Van Wassenbergh, Sam

    2013-08-01

    In contrast to numerous studies on the function of the locomotor system used by fishes when moving between water and land, little knowledge is available about the biomechanical requirements to the capture and transport of food by fish in a terrestrial situation. This study focuses on the kinematics of terrestrial capture of prey by the eel-catfish (Channallabes apus: Clariidae), a behavior that was only recently discovered for this species. The analyses show that C. apus inclines its head downward at a significantly steeper angle during terrestrial feeding compared with benthic aquatic feeding. This suggests that placing the jaws above ground-based prey is important for successful prehension by the jaws. The increased inclination of the head resulted from accumulated dorsoventral flexion of the body more than one head-length behind the skull. Alternatively, this posture of the head was assumed by rolling to one side while bending the body laterally. The speed of buccopharyngeal expansion in air versus in water matched the predicted increase by a factor of 3, under the assumption that the velocity of muscular contraction for maximal output of power by C. apus is optimized to operate under a specific hydrodynamic loading, and shifts to an unloaded contraction regime when operating in air. Combining these insights with future studies on other extant amphibious fish species that perform terrestrial feeding may eventually allow us to pinpoint the adaptations to the feeding system that have led to the evolution of a terrestrial lifestyle in tetrapods. PMID:23624865

  16. Vasodilator Effects of Elcatonin, a Synthetic Eel Calcitonin, on Retinal Blood Vessels in Rats.

    PubMed

    Mori, Asami; Suzawa, Hironori; Sakamoto, Kenji; Nakahara, Tsutomu; Ishii, Kunio

    2015-01-01

    The aim of this study was to examine the effects of elcatonin, a synthetic derivative of eel calcitonin, on rat retinal blood vessels, and to determine how diabetes affects the retinal vascular responses. Ocular fundus images were captured with an original high-resolution digital fundus camera in vivo. The retinal vascular responses were evaluated by measuring the diameter of retinal blood vessels contained in the digital images. Both systemic blood pressure and heart rate were continuously recorded. Elcatonin increased the diameter of retinal blood vessels but decreased mean blood pressure in a dose-dependent manner, whereas it had no significant effect on heart rate. A diminished retinal vasodilator response and significant pressor response to elcatonin were observed in rats injected intravenously with N(G)-nitro-L-arginine methyl ester, a nitric oxide (NO) synthase inhibitor. Intravitreal injection of indomethacin, a non-selective cyclooxygenase (COX) inhibitor, and SQ22536, an adenylyl cyclase inhibitor, markedly attenuated the vasodilator effects of elcatonin on retinal blood vessels. The retinal vasodilator responses to elcatonin were unaffected 2 weeks after the induction of diabetes by a combination of streptozotocin treatment and D-glucose feeding. These results suggest that elcatonin dilates rat retinal blood vessels via NO- and COX-dependent mechanisms and that the adenylyl cyclase-adenosine 3',5'-cyclic monophosphate system plays a major role in the vasodilator mechanisms. The retinal vasodilatory effects of elcatonin seem to be preserved at early stages of diabetes. PMID:26424018

  17. Quantitative Phase Fraction Detection in Organic Photovoltaic Materials through EELS Imaging

    SciTech Connect

    Dyck, Ondrej; Hu, Sheng; Das, Sanjib; Keum, Jong; Xiao, Kai; Khomami, Bamin; Duscher, Gerd

    2015-11-24

    Organic photovoltaic materials have recently seen intense interest from the research community. Improvements in device performance are occurring at an impressive rate; however, visualization of the active layer phase separation still remains a challenge. Our paper outlines the application of two electron energy-loss spectroscopic (EELS) imaging techniques that can complement and enhance current phase detection techniques. Specifically, the bulk plasmon peak position, often used to produce contrast between phases in energy filtered transmission electron microscopy (EFTEM), is quantitatively mapped across a sample cross section. One complementary spectrum image capturing the carbon and sulfur core loss edges is compared with the plasmon peak map and found to agree quite well, indicating that carbon and sulfur density differences between the two phases also allows phase discrimination. Additionally, an analytical technique for determining absolute atomic areal density is used to produce an absolute carbon and sulfur areal density map. We also show how these maps may be re-interpreted as a phase ratio map, giving quantitative information about the purity of the phases within the junction.

  18. Quantitative Phase Fraction Detection in Organic Photovoltaic Materials through EELS Imaging

    DOE PAGESBeta

    Dyck, Ondrej; Hu, Sheng; Das, Sanjib; Keum, Jong; Xiao, Kai; Khomami, Bamin; Duscher, Gerd

    2015-11-24

    Organic photovoltaic materials have recently seen intense interest from the research community. Improvements in device performance are occurring at an impressive rate; however, visualization of the active layer phase separation still remains a challenge. Our paper outlines the application of two electron energy-loss spectroscopic (EELS) imaging techniques that can complement and enhance current phase detection techniques. Specifically, the bulk plasmon peak position, often used to produce contrast between phases in energy filtered transmission electron microscopy (EFTEM), is quantitatively mapped across a sample cross section. One complementary spectrum image capturing the carbon and sulfur core loss edges is compared with themore » plasmon peak map and found to agree quite well, indicating that carbon and sulfur density differences between the two phases also allows phase discrimination. Additionally, an analytical technique for determining absolute atomic areal density is used to produce an absolute carbon and sulfur areal density map. We also show how these maps may be re-interpreted as a phase ratio map, giving quantitative information about the purity of the phases within the junction.« less

  19. Kleptoparasitism and aggressiveness are influenced by standard metabolic rate in eels.

    PubMed

    Geffroy, Benjamin; Bolliet, Valérie; Bardonnet, Agnès

    2016-04-01

    Kleptoparasitism refers to either interspecific or intraspecific stealing of food already procured by other species or individuals. Within a given species, individuals might differ in their propensity to use such a tactic, in a similar manner to which they differ in their general level of aggressiveness. Standard metabolic rate is often viewed as a proxy for energy requirements. For this reason, it should directly impact on both kleptoparasitism and aggressiveness when individuals have to share the same food source. In the present study we first assessed the standard metabolic rate (SMR) of 128 juvenile European eels (Anguilla anguilla) by the determination of oxygen consumption. We then tested how the SMR could influence agonistic behavior of individuals competing for food in three distinct trials evenly distributed over three months. We demonstrate that SMR positively correlates with attacks (sum of bite and push events) in all trials. Similarly SMR correlated positively with kleptoparasitism (food theft), but this was significant only for the third trial (month 3). To our knowledge, the present study is the first reporting a link between kleptoparasitism and SMR in a fish species. This has ecological implications owing to the fact that this species is characterized by an environmental sex determination linked to early growth rate. We discuss theses findings in the light of the producer-scrounger foraging game. PMID:26861178

  20. In Situ STEM-EELS Observation of Nanoscale Interfacial Phenomena in All-Solid-State Batteries.

    PubMed

    Wang, Ziying; Santhanagopalan, Dhamodaran; Zhang, Wei; Wang, Feng; Xin, Huolin L; He, Kai; Li, Juchuan; Dudney, Nancy; Meng, Ying Shirley

    2016-06-01

    Behaviors of functional interfaces are crucial factors in the performance and safety of energy storage and conversion devices. Indeed, solid electrode-solid electrolyte interfacial impedance is now considered the main limiting factor in all-solid-state batteries rather than low ionic conductivity of the solid electrolyte. Here, we present a new approach to conducting in situ scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) in order to uncover the unique interfacial phenomena related to lithium ion transport and its corresponding charge transfer. Our approach allowed quantitative spectroscopic characterization of a galvanostatically biased electrochemical system under in situ conditions. Using a LiCoO2/LiPON/Si thin film battery, an unexpected structurally disordered interfacial layer between LiCoO2 cathode and LiPON electrolyte was discovered to be inherent to this interface without cycling. During in situ charging, spectroscopic characterization revealed that this interfacial layer evolved to form highly oxidized Co ions species along with lithium oxide and lithium peroxide species. These findings suggest that the mechanism of interfacial impedance at the LiCoO2/LiPON interface is caused by chemical changes rather than space charge effects. Insights gained from this technique will shed light on important challenges of interfaces in all-solid-state energy storage and conversion systems and facilitate improved engineering of devices operated far from equilibrium. PMID:27140196

  1. Protein engineering of conger eel galectins by tracing of molecular evolution using probable ancestral mutants

    PubMed Central

    2010-01-01

    Background Conger eel galectins, congerin I (ConI) and congerin II (ConII), show the different molecular characteristics resulting from accelerating evolution. We recently reconstructed a probable ancestral form of congerins, Con-anc. It showed properties similar to those of ConII in terms of thermostability and carbohydrate recognition specificity, although it shares a higher sequence similarity with ConI than ConII. Results In this study, we have focused on the different amino acid residues between Con-anc and ConI, and have performed the protein engineering of Con-anc through site-directed mutagenesis, followed by the molecular evolution analysis of the mutants. This approach revealed the functional importance of loop structures of congerins: (1) N- and C-terminal and loop 5 regions that are involved in conferring a high thermostability to ConI; (2) loops 3, 5, and 6 that are responsible for stronger binding of ConI to most sugars; and (3) loops 5 and 6, and Thr38 residue in loop 3 contribute the specificity of ConI toward lacto-N-fucopentaose-containing sugars. Conclusions Thus, this methodology, with tracing of the molecular evolution using ancestral mutants, is a powerful tool for the analysis of not only the molecular evolutionary process, but also the structural elements of a protein responsible for its various functions. PMID:20152053

  2. The decline of the European eel Anguilla anguilla: quantifying and managing escapement to support conservation.

    PubMed

    Bilotta, G S; Sibley, P; Hateley, J; Don, A

    2011-01-01

    A method was developed to quantify the number and biomass of European eels Anguilla anguilla escaping to the ocean for breeding. The non-intrusive method, involving a fixed-position, high-frequency multi-beam sonar, permitted constant surveillance of A. anguilla movements throughout their 5 month escapement season (July to December). During this period, >1000 individuals were monitored escaping to the Atlantic Ocean from their freshwater habitat in the River Huntspill study site (Somerset, U.K.). The total length of each fish was measured using the sonar software. These measurements were then converted to an estimate of mass using a length:mass regression relationship derived from historical fyke-net data from this site, comprising c. 500 A. anguilla length:mass measurements collected over a 10 year period. The net biomass of escapement from the study site was equivalent to c. 6 kg ha⁻¹ year⁻¹, lower than the present European target which would require at least 7 kg ha⁻¹ year⁻¹ from this habitat. These findings demonstrate the capabilities of this monitoring technique and its usefulness both as a tool to assess the compliance with conservation targets and as a tool to evaluate the success of conservation measures for elusive aquatic species such as A. anguilla. PMID:21235544

  3. The Untold Story of the Caudal Skeleton in the Electric Eel (Ostariophysi: Gymnotiformes: Electrophorus)

    PubMed Central

    de Santana, Carlos David; Vari, Richard P.; Wosiacki, Wolmar B.

    2013-01-01

    Alternative hypotheses had been advanced as to the components forming the elongate fin coursing along the ventral margin of much of the body and tail from behind the abdominal region to the posterior margin of the tail in the Electric Eel, Electrophorus electricus. Although the original species description indicated that this fin was a composite of the caudal fin plus the elongate anal fin characteristic of other genera of the Gymnotiformes, subsequent researchers proposed that the posterior region of the fin was formed by the extension of the anal fin posteriorly to the tip of the tail, thereby forming a “false caudal fin.” Examination of ontogenetic series of the genus reveal that Electrophorus possesses a true caudal fin formed of a terminal centrum, hypural plate and a low number of caudal-fin rays. The confluence of the two fins is proposed as an additional autapomorphy for the genus. Under all alternative proposed hypotheses of relationships within the order Gymnotiformes, the presence of a caudal fin in Electrophorus optimized as being independent of the occurence of the morphologically equivalent structure in the Apteronotidae. Possible functional advantages to the presence of a caudal fin in the genus are discussed. PMID:23894337

  4. 40 CFR 421.120 - Applicability: Description of the secondary silver subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... secondary silver subcategory. 421.120 Section 421.120 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Silver Subcategory § 421.120 Applicability: Description of the secondary silver... silver from secondary silver facilities processing photographic and nonphotographic raw materials....

  5. 40 CFR 421.120 - Applicability: Description of the secondary silver subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... secondary silver subcategory. 421.120 Section 421.120 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Silver Subcategory § 421.120 Applicability: Description of the secondary silver... silver from secondary silver facilities processing photographic and nonphotographic raw materials....

  6. 40 CFR 421.120 - Applicability: Description of the secondary silver subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... secondary silver subcategory. 421.120 Section 421.120 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Silver Subcategory § 421.120 Applicability: Description of the secondary silver... silver from secondary silver facilities processing photographic and nonphotographic raw materials....

  7. 40 CFR 421.120 - Applicability: Description of the secondary silver subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... secondary silver subcategory. 421.120 Section 421.120 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Silver Subcategory § 421.120 Applicability: Description of the secondary silver... silver from secondary silver facilities processing photographic and nonphotographic raw materials....

  8. 40 CFR 421.120 - Applicability: Description of the secondary silver subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... secondary silver subcategory. 421.120 Section 421.120 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Silver Subcategory § 421.120 Applicability: Description of the secondary silver... silver from secondary silver facilities processing photographic and nonphotographic raw materials....

  9. Risk assessment of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Shipelin, V. A.; Gmoshinski, I. V.; Khotimchenko, S. A.

    2015-11-01

    Nanoparticles of metallic silver (Ag) are among the most widely used products of nanotechnology. Nanosized colloidal silver (NCS) is presented in many kinds of production as solutions of particles with diameter less than 100 nm. NCS is used in a variety of fields, including food supplements, medicines, cosmetics, packaging materials, disinfectants, water filters, and many others. Problems of toxicity and related safety of NCS for humans and environmental systems are recently overestimated basing on data of numerous toxicological studies in vitro and in vivo. The article discusses the results of current studies in recent years and the data of author's own experiments on studying the safety of NCS, that allows to move on to risk assessment of this nanomaterial presented in consumer products and environmental samples.

  10. Antibacterial potential of silver nanoparticles against isolated urinary tract infectious bacterial pathogens

    NASA Astrophysics Data System (ADS)

    Jacob Inbaneson, Samuel; Ravikumar, Sundaram; Manikandan, Nachiappan

    2011-12-01

    The silver nanoparticles were synthesized by chemical reduction method and the nanoparticles were characterized using ultraviolet-visible (UV-Vis) absorption spectroscopy and X-ray diffraction (XRD) studies. The synthesized silver nanoparticles were investigated to evaluate the antibacterial activity against urinary tract infectious (UTIs) bacterial pathogens. Thirty-two bacteria were isolated from mid urine samples of 25 male and 25 female patients from Thondi, Ramanathapuram District, Tamil Nadu, India and identified by conventional methods. Escherichia coli was predominant (47%) followed by Pseudomonas aeruginosa (22%), Klebsiella pneumoniae (19%), Enterobacter sp. (6%), Proteus morganii (3%) and Staphylococcus aureus (3%). The antibacterial activity of silver nanoparticles was evaluated by disc diffusion assay. P. aeruginosa showed maximum sensitivity (11 ± 0.58 mm) followed by Enterobacter sp. (8 ± 0.49 mm) at a concentration of 20 μg disc-1 and the sensitivity was highly comparable with the positive control kanamycin and tetracycline. K. pneumoniae, E. coli, P. morganii and S. aureus showed no sensitivity against all the tested concentrations of silver nanoparticles. The results provided evidence that, the silver nanoparticles might indeed be the potential sources to treat urinary tract infections caused by P. aeruginosa and Enterobacter sp.

  11. Synthesis and optical properties of silver nanoparticles

    SciTech Connect

    Singh, Jaiveer; Kaurav, Netram; Choudhary, K. K.; Okram, Gunadhor S.

    2015-07-31

    The preparation of stable, uniform silver nanoparticles by reduction of silver acetate by ethylene glycol (EG) is reported in the present paper. It is a simple process of recent interest for obtaining silver nanoparticles. The samples were characterized by X-Ray diffraction (XRD), which reveals an average particle size (D) of 38 nm. The UV/Vis spectra show that an absorption peak, occurring due to surface plasmon resonance (SPR), exists at 319 nm.

  12. Fluorescent silver nanoclusters as DNA probes

    NASA Astrophysics Data System (ADS)

    Obliosca, Judy M.; Liu, Cong; Yeh, Hsin-Chih

    2013-08-01

    Fluorescent silver nanoclusters (few atoms, quantum sized) have attracted much attention as promising substitutes for conventional fluorophores. Due to their unique environmental sensitivities, new fluorescent probes have been developed based on silver nanoclusters for the sensitive and specific detection of DNA. In this review we present the recent discoveries of activatable and color-switchable properties of DNA-templated silver nanoclusters and discuss the strategies to use these new properties in DNA sensing.

  13. Female Prisoners in Malaysia

    ERIC Educational Resources Information Center

    Teh, Yik Koon

    2006-01-01

    This is a study on 422 female prisoners in peninsular Malaysia. More than half of the female prisoners are foreigners, mainly from Indonesia and Thailand. This study surveys the background of the respondents and identifies factors that may have influenced them to commit the offences. Female prisoners in Malaysia, particularly those who are…

  14. Silver europium(III) polyphosphate

    PubMed Central

    Ayadi, Mounir; Férid, Mokhtar; Moine, Bernard

    2009-01-01

    Europium(III) silver polyphosphate, AgEu(PO3)4, was prepared by the flux method. The atomic arrangement is built up by infinite (PO3)n chains (periodicity of 4) extending along the c axis. These chains are joined to each other by EuO8 dodeca­hedra. The Ag+ cations are located in the voids of this arrangement and are surrounded by five oxygen atoms in a distorted [4+1] coordination. PMID:21582031

  15. The catadromous European eel Anguilla anguilla (L.) as a model for freshwater evolutionary ecotoxicology: relationship between heavy metal bioaccumulation, condition and genetic variability.

    PubMed

    Maes, G E; Raeymaekers, J A M; Pampoulie, C; Seynaeve, A; Goemans, G; Belpaire, C; Volckaert, F A M

    2005-06-01

    Understanding the effects of pollutants on the genome is of crucial importance to preserve the evolutionary potential of endangered natural populations. The highly vagile European eel (Anguilla anguilla L.) has suffered a dramatic decline in recruitment since two decades, urging for a better understanding of the genetic impact of pollution. Its catadromous life history constitutes a model to assess local selection of pollutants on condition and genetic variability, as juveniles recruit in European rivers without appreciable pollution load or interfering genetic background. Because of its high fat content and local benthic feeding behaviour, the feeding stage is considered extremely prone to the bioaccumulation of pollutants. We studied the relationship between heavy metal bioaccumulation, fitness (condition) and genetic variability in the European eel. The muscle tissues of 78 sub-adult eels, originating from three Belgian river basins (Scheldt, Meuse and Yser), were examined for nine heavy metal pollutants (Hg, Cd, Pb, Cu, Zn, Ni, Cr, As and Se), while in total 123 individuals were genotyped at 12 allozyme and 8 microsatellite loci. A significant negative correlation between heavy metal pollution load and condition was observed, suggesting an impact of pollution on the health of sub-adult eels. In general, we observed a reduced genetic variability in strongly polluted eels, as well as a negative correlation between level of bioaccumulation and allozymatic multi-locus heterozygosity (MLH). Microsatellite genetic variability did not show any pollution related differences, suggesting a differential response at metabolic enzymes and possibly direct overdominance of heterozygous individuals. PMID:15892996

  16. Offshore spawning of Conger myriaster in the western North Pacific: evidence for convergent migration strategies of anguilliform eels in the Atlantic and Pacific.

    PubMed

    Miller, Michael J; Yoshinaga, Tatsuki; Aoyama, Jun; Otake, Tsuguo; Mochioka, Noritaka; Kurogi, Hiroaki; Tsukamoto, Katsumi

    2011-06-01

    The spawning area of the common Japanese conger, Conger myriaster, had remained unknown because spawning adults or its newly hatched larvae were never collected. Using genetic identification, we determined that C. myriaster spawns far offshore in the western North Pacific, just west of the spawning area of the Japanese eel, Anguilla japonica. In June 2008, six newly hatched C. myriaster larvae, 5.6-6.9 mm, were collected at the eastern edge of where many small unidentified Conger leptocephali (7-20 mm) were collected previously. The offshore spawning location of C. myriaster is analogous to that of the American conger eel, Conger oceanicus, and the American eel, Anguilla rostrata, in the Sargasso Sea, suggesting that convergent evolution of large-scale reproductive migration strategies in both anguillid and conger eels has occurred in the north Atlantic and Pacific subtropical gyres. The realization that two anguillids, A. rostrata and A. japonica, and two congers, C. oceanicus and C. myriaster, have evolved almost identical migration strategies in widely separated ocean basins suggests that natural selection for larval survival and recruitment success has resulted in long offshore spawning migrations in two phylogenetically distant taxa of anguilliform eels. PMID:21509576

  17. Offshore spawning of Conger myriaster in the western North Pacific: evidence for convergent migration strategies of anguilliform eels in the Atlantic and Pacific

    NASA Astrophysics Data System (ADS)

    Miller, Michael J.; Yoshinaga, Tatsuki; Aoyama, Jun; Otake, Tsuguo; Mochioka, Noritaka; Kurogi, Hiroaki; Tsukamoto, Katsumi

    2011-06-01

    The spawning area of the common Japanese conger, Conger myriaster, had remained unknown because spawning adults or its newly hatched larvae were never collected. Using genetic identification, we determined that C. myriaster spawns far offshore in the western North Pacific, just west of the spawning area of the Japanese eel, Anguilla japonica. In June 2008, six newly hatched C. myriaster larvae, 5.6-6.9 mm, were collected at the eastern edge of where many small unidentified Conger leptocephali (7-20 mm) were collected previously. The offshore spawning location of C. myriaster is analogous to that of the American conger eel, Conger oceanicus, and the American eel, Anguilla rostrata, in the Sargasso Sea, suggesting that convergent evolution of large-scale reproductive migration strategies in both anguillid and conger eels has occurred in the north Atlantic and Pacific subtropical gyres. The realization that two anguillids, A. rostrata and A. japonica, and two congers, C. oceanicus and C. myriaster, have evolved almost identical migration strategies in widely separated ocean basins suggests that natural selection for larval survival and recruitment success has resulted in long offshore spawning migrations in two phylogenetically distant taxa of anguilliform eels.

  18. Fabrication of Silver Nano-Noodles

    NASA Astrophysics Data System (ADS)

    Iwanabe, Yasuhiko; Horiuchi, Toshiyuki; Tominaga, Junji; Büchel, Dorothea; Mihalcea, Christophe

    2003-10-01

    We report that silver nanowires can easily be fabricated from organic solution including silver ions by focusing a laser beam on a light absorbing material surface. Focusing a laser beam on a Si film (100-nm thickness on a glass substrate) in silver oxide (AgOx) saturated benzoic acid (BA) (10-3 M)-2-propanol (IPA) solution produced noodle-like silver nanowires with diameters of less than 50 nm. It was suggested that the Ag nanowires were formed by super-cooling effect at local heating and solubility around the laser spot region, and transported to the laser spot area by thermal convection.

  19. Silver staining of proteins in polyacrylamide gels

    PubMed Central

    Chevallet, Mireille; Luche, Sylvie; Rabilloud, Thierry

    2006-01-01

    Silver staining is used to detect proteins after electrophoretic separation on polyacrylamide gels. It combines excellent sensitivity (in the low nanogram range) whilst using very simple and cheap equipment and chemicals. It is compatible with downstream processing such as mass spectrometry analysis after protein digestion. The sequential phases of silver staining are protein fixation, then sensitization, then silver impregnation and finally image development. Several variants of silver staining are described here, which can be completed in a time range from 2 hours to one day after the end of the electrophoretic separation. Once completed, the stain is stable for several weeks PMID:17487168

  20. Morphology of a silver/polyacrylonitrile nanocomposite

    NASA Astrophysics Data System (ADS)

    Kudryashov, M. A.; Mashin, A. I.; Tyurin, A. S.; Fedosov, A. E.; Chidichimo, G.; De Filpo, G.

    2011-01-01

    Silver/polyacrylonitrile (Ag/PAN) nanocomposites are synthesized at the stage of simultaneous acrylonitrile polymerization and the reduction of silver ions from a mixture of silver nitrate AgNO3, acrylonitrile, and a photoinitiator. The synthesized films are transparent in the visible region and are characterized by a uniform dispersion of silver nanoparticles in a PAN matrix without any macroscopic agglomeration. The effects of the metal salt and photoinitiator concentrations on the size and density of metal nanoparticles in a composite are revealed.

  1. Estimation of daily age and timing of hatching of exotic Asian swamp eels Monopterus albus (Zuiew, 1793) in a backwater marsh of the Chattahoochee River, Georgia, USA

    USGS Publications Warehouse

    Long, James M.; Lafleur, C.

    2011-01-01

    Otoliths were used to estimate daily age, growth, and hatching date of the exotic Asian swamp eel (Monopterus albus) captured from a backwater marsh of the Chattahoochee River, Georgia, USA. The eels were sampled using leaf litter traps (N = 140) from 17 July to 28 August 2008. The captured (N = 15) Asian swamp eels ranged in total length from 4.9 cm to 12.2 cm, and were estimated to be from 21 to 51 days old (N = 13), and hatched from 13 June to 7 August 2008. Assuming linear growth, these individuals grew an average rate of 0.2 cm per day. To the authors' knowledge, this was the first time otoliths were used to estimate daily age, growth, and hatching date for M. albus, which can be useful for understanding the ecology of this species in the wild.

  2. Estimation of daily age and timing of hatching of exotic Asian swamp eels Monopterus albus (Zuiew, 1793) in a backwater marsh of the Chattahoochee River, Georgia, USA

    USGS Publications Warehouse

    Long, J.M.; Lafleur, C.

    2011-01-01

    Otoliths were used to estimate daily age, growth, and hatching date of the exotic Asian swamp eel (Monopterus albus) captured from a backwater marsh of the Chattahoochee River, Georgia, USA. The eels were sampled using leaf litter traps (N=140) from 17 July to 28 August 2008. The captured (N=15) Asian swamp eels ranged in total length from 4.9cm to 12.2cm, and were estimated to be from 21 to 51days old (N=13), and hatched from 13 June to 7 August 2008. Assuming linear growth, these individuals grew an average rate of 0.2cm per day. To the authors' knowledge, this was the first time otoliths were used to estimate daily age, growth, and hatching date for M. albus, which can be useful for understanding the ecology of this species in the wild. Published 2011. This article is a US Government work and is in the public domain in the USA.

  3. Room temperature synthesis of silver nanowires from tabular silver bromide crystals in the presence of gelatin

    SciTech Connect

    Liu Suwen; Wehmschulte, Rudolf J. . E-mail: rwehmsch@fit.edu; Lian Guoda; Burba, Christopher M.

    2006-03-15

    Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 {mu}m, some even more than 100 {mu}m, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the silver nanowires grow along the [111] direction. It was found that the presence of gelatin, tabular silver bromide crystals and silver ions in solution are essential for the formation of the silver nanowires. The nanowires appear to originate from the edges of the silver bromide crystals. They were characterized by transmission electron microscopy (TEM), SAED, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD)

  4. Toxicity of various silver nanoparticles compared to silver ions in Daphnia magna

    PubMed Central

    2012-01-01

    Background To better understand the potential ecotoxicological impacts of silver nanoparticles released into freshwater environments, the Daphnia magna 48-hour immobilization test was used. Methods The toxicities of silver nitrate, two types of colloidal silver nanoparticles, and a suspension of silver nanoparticles were assessed and compared using standard OECD guidelines. Also, the swimming behavior and visible uptake of the nanoparticles by Daphnia were investigated and compared. The particle suspension and colloids used in the toxicity tests were well-characterized. Results The results obtained from the exposure studies showed that the toxicity of all the silver species tested was dose and composition dependent. Plus, the silver nanoparticle powders subsequently suspended in the exposure water were much less toxic than the previously prepared silver nanoparticle colloids, whereas the colloidal silver nanoparticles and AgNO3 were almost similar in terms of mortality. The silver nanoparticles were ingested by the Daphnia and accumulated under the carapace, on the external body surface, and connected to the appendages. All the silver species in this study caused abnormal swimming by the D. magna. Conclusion According to the present results, silver nanoparticles should be classified according to GHS (Globally Harmonized System of classification and labeling of chemicals) as "category acute 1" to Daphnia neonates, suggesting that the release of nanosilver into the environment should be carefully considered. PMID:22472056

  5. Glass frits coated with silver nanoparticles for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yingfen; Gan, Weiping; Zhou, Jian; Li, Biyuan

    2015-06-01

    Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells.

  6. Development of nanostructured silver vanadates decorated with silver nanoparticles as a novel antibacterial agent

    NASA Astrophysics Data System (ADS)

    Holtz, R. D.; Souza Filho, A. G.; Brocchi, M.; Martins, D.; Durán, N.; Alves, O. L.

    2010-05-01

    In this work we report the synthesis, characterization and application of silver vanadate nanowires decorated with silver nanoparticles as a novel antibacterial agent. These hybrid materials were synthesized by a precipitation reaction of ammonium vanadate and silver nitrate followed by hydrothermal treatment. The silver vanadate nanowires have lengths of the order of microns and diameters around 60 nm. The silver nanoparticles decorating the nanowires present a diameter distribution varying from 1 to 20 nm. The influence of the pH of the reaction medium on the chemical structure and morphology of silver vanadates was studied and we found that synthesis performed at pH 5.5-6.0 led to silver vanadate nanowires with a higher morphological yield. The antimicrobial activity of these materials was evaluated against three strains of Staphylococcus aureus and very promising results were found. The minimum growth inhibiting concentration value against a MRSA strain was found to be ten folds lower than for the antibiotic oxacillin.

  7. The Female Gametophyte

    PubMed Central

    Drews, Gary N.; Koltunow, Anna M.G

    2011-01-01

    The angiosperm female gametophyte is critical for plant reproduction. It contains the egg cell and central cell that become fertilized and give rise to the embryo and endosperm of the seed, respectively. Female gametophyte development begins early in ovule development with the formation of a diploid megaspore mother cell that undergoes meiosis. One resulting haploid megaspore then develops into the female gametophyte. Genetic and epigenetic processes mediate specification of megaspore mother cell identity and limit megaspore mother cell formation to a single cell per ovule. Auxin gradients influence female gametophyte polarity and a battery of transcription factors mediate female gametophyte cell specification and differentiation. The mature female gametophyte secretes peptides that guide the pollen tube to the embryo sac and contains protein complexes that prevent seed development before fertilization. Post-fertilization, the female gametophyte influences seed development through maternal-effect genes and by regulating parental contributions. Female gametophytes can form by an asexual process called gametophytic apomixis, which involves formation of a diploid female gametophyte and fertilization-independent development of the egg into the embryo. These functions collectively underscore the important role of the female gametophyte in seed and food production. PMID:22303279

  8. The female gametophyte.

    PubMed

    Drews, Gary N; Koltunow, Anna M G

    2011-01-01

    The angiosperm female gametophyte is critical for plant reproduction. It contains the egg cell and central cell that become fertilized and give rise to the embryo and endosperm of the seed, respectively. Female gametophyte development begins early in ovule development with the formation of a diploid megaspore mother cell that undergoes meiosis. One resulting haploid megaspore then develops into the female gametophyte. Genetic and epigenetic processes mediate specification of megaspore mother cell identity and limit megaspore mother cell formation to a single cell per ovule. Auxin gradients influence female gametophyte polarity and a battery of transcription factors mediate female gametophyte cell specification and differentiation. The mature female gametophyte secretes peptides that guide the pollen tube to the embryo sac and contains protein complexes that prevent seed development before fertilization. Post-fertilization, the female gametophyte influences seed development through maternal-effect genes and by regulating parental contributions. Female gametophytes can form by an asexual process called gametophytic apomixis, which involves formation of a diploid female gametophyte and fertilization-independent development of the egg into the embryo. These functions collectively underscore the important role of the female gametophyte in seed and food production. PMID:22303279

  9. The Aetiology, Histopathology, and Ultrastructural Features of Perianal Erythema (Red Anus Syndrome) in the European Eel (Anguilla anguilla)

    PubMed Central

    Tamam, Omar A. S.

    2014-01-01

    The European eel (Anguilla anguilla) is a critically endangered species. Red anus syndrome (RAS) is known to be associated with parasitic infections of the eel, particularly with Anguillicola crassus, but the full range of causative pathogenic organisms has not been systematically investigated. Here we examined the infective organisms and histopathological and ultrastructural features of seventy eels with RAS. In total, nine different pathogens were detected in association with RAS: Pseudomonas aeruginosa were present in twelve specimens (17%), the metacercaria of Euclinostromum heterostomum in three cases (4%), Gastrostome (Bucephalidae family) in seven cases (10%), A. crassus in forty-five cases (64%), Bothriocephalus in seventeen cases (24%), and Proteocephalus in twenty-three cases (32%). Yeast, amoeba, and myxobolus-like pathogens were seen in the anal skin in all cases when examined in combination with electron microscopy. Histopathologically, the lesions appeared as anoproctitis of varying severity from mild anusitis to severe haemorrhagic anoproctitis, with severe perianal oedema, haemorrhage, and proctoptosis. Gut inflammation ranged from mild catarrhal enteritis to severe haemorrhagic enteritis with mucosal sloughing. RAS is associated with a range of parasitic infections, not only A. crassus, some of which we describe here for the first time. Since RAS is not associated with direct invasion by parasites, it is likely that RAS is a secondary phenomenon caused by superadded infection on a background of generalised immunosuppression, or indirect local toxic effects. RAS may be used as a non-invasive indicator of underlying parasitic infection, but further investigations are required to establish the causative organisms for effective fishery management. PMID:24608418

  10. iTRAQ proteomic analysis of salinity acclimation proteins in the gill of tropical marbled eel (Anguilla marmorata).

    PubMed

    Jia, Yihe; Yin, Shaowu; Li, Li; Li, Peng; Liang, Fenfei; Wang, Xiaolu; Wang, Xiaojun; Wang, Li; Su, Xinhua

    2016-06-01

    Osmoregulation plays an important role in the migration process of catadromous fish. The osmoregulatory mechanisms of tropical marbled eel (Anguilla marmorata), a typical catadromous fish, did not gain sufficient attention, especially at the molecular level. In order to enrich the protein database of A. marmorata, a proteomic analysis has been carried out by iTRAQ technique. Among 1937 identified proteins in gill of marbled eel, the expression of 1560 proteins (80 %) was quantified. Compared with the protein expression level in the gill of marbled eel in freshwater (salinity of 0 ‰), 336 proteins were up-regulated and 67 proteins were down-regulated in seawater (salinity of 25 ‰); 33 proteins were up-regulated and 32 proteins were down-regulated in brackish water (salinity of 10 ‰). These up-regulated proteins including Na(+)/K(+)-ATPase, V-type proton ATPase, sodium-potassium-chloride co-transporter and heat shock protein 90 were enriched in many KEGG-annotated pathways, which are related to different functions of the gill. The up-regulated oxidative phosphorylation and seleno-compound metabolism pathways involve the synthesis and consumption of ATP, which represents extra energy consumption. Another identified pathway is the ribosome pathway in which a large number of up-regulated proteins are involved. It is also more notable that tight junction and cardiac muscle contraction pathways may have correlation with ion transport in gill cells. This is the first report describing the proteome of A. marmorata for acclimating to the change of salinity. These results provide a functional database for migratory fish and point out some possible new interactions on osmoregulation in A. marmorata. PMID:26721661

  11. Gene transcription profiling in wild and laboratory-exposed eels: Effect of captivity and in situ chronic exposure to pollution.

    PubMed

    Baillon, Lucie; Pierron, Fabien; Pannetier, Pauline; Normandeau, Eric; Couture, Patrice; Labadie, Pierre; Budzinski, Hélène; Lambert, Patrick; Bernatchez, Louis; Baudrimont, Magalie

    2016-11-15

    Aquatic ecosystems are subjected to a variety of man-induced stressors but also vary spatially and temporally due to variation in natural factors. In such complex environments, it remains difficult to detect, dissociate and evaluate the effects of contaminants in wild organisms. In this context, the aim of this study was to test whether the hepatic transcriptome profile of fish may be used to detect in situ exposure to a particular contaminant. Transcriptomic profiles from laboratory-exposed and wild eels sampled along a contamination gradient were compared. During laboratory experiments, fish were exposed during 45days to different pollutants (Hg, PCBs, OCPs or Cd) or natural factors (temperature, salinity or low food supply) at levels close to those found in the sampling sites. A strong difference was observed between the transcriptomic profiles obtained from wild and laboratory-exposed animals (whatever the sites or experimental conditions), suggesting a general stress induced by captivity in the laboratory. Among the biological functions that were up-regulated in laboratory eels in comparison to wild eels, histone modification was the most represented. This finding suggests that laboratory conditions could affect the epigenome of fish and thus modulate the transcriptional responses developed by fish in response to pollutant exposure. Among experimental conditions, only the transcription profiles of laboratory animals exposed to cold temperature were correlated with those obtained from wild fish, and more significantly with fish from contaminated sites. Common regulated genes were mainly involved in cell differentiation and liver development, suggesting that stem/progenitor liver cells could be involved in the adaptive response developed by fish chronically exposed to pollutant mixtures. PMID:27470668

  12. Do trout swim better than eels? Challenges for estimating performance based on the wake of self-propelled bodies

    NASA Astrophysics Data System (ADS)

    Tytell, Eric D.

    Engineers and biologists have long desired to compare propulsive performance for fishes and underwater vehicles of different sizes, shapes, and modes of propulsion. Ideally, such a comparison would be made on the basis of either propulsive efficiency, total power output or both. However, estimating the efficiency and power output of self-propelled bodies, and particularly fishes, is methodologically challenging because it requires an estimate of thrust. For such systems traveling at a constant velocity, thrust and drag are equal, and can rarely be separated on the basis of flow measured in the wake. This problem is demonstrated using flow fields from swimming American eels, Anguilla rostrata, measured using particle image velocimetry (PIV) and high-speed video. Eels balance thrust and drag quite evenly, resulting in virtually no wake momentum in the swimming (axial) direction. On average, their wakes resemble those of self-propelled jet propulsors, which have been studied extensively. Theoretical studies of such wakes may provide methods for the estimation of thrust separately from drag. These flow fields are compared with those measured in the wakes of rainbow trout, Oncorhynchus mykiss, and bluegill sunfish, Lepomis macrochirus. In contrast to eels, these fishes produce wakes with axial momentum. Although the net momentum flux must be zero on average, it is neither spatially nor temporally homogeneous; the heterogeneity may provide an alternative route for estimating thrust. This review shows examples of wakes and velocity profiles from the three fishes, indicating challenges in estimating efficiency and power output and suggesting several routes for further experiments. Because these estimates will be complicated, a much simpler method for comparing performance is outlined, using as a point of comparison the power lost producing the wake. This wake power, a component of the efficiency and total power, can be estimated in a straightforward way from the flow

  13. Do trout swim better than eels? Challenges for estimating performance based on the wake of self-propelled bodies

    NASA Astrophysics Data System (ADS)

    Tytell, Eric D.

    2007-11-01

    Engineers and biologists have long desired to compare propulsive performance for fishes and underwater vehicles of different sizes, shapes, and modes of propulsion. Ideally, such a comparison would be made on the basis of either propulsive efficiency, total power output or both. However, estimating the efficiency and power output of self-propelled bodies, and particularly fishes, is methodologically challenging because it requires an estimate of thrust. For such systems traveling at a constant velocity, thrust and drag are equal, and can rarely be separated on the basis of flow measured in the wake. This problem is demonstrated using flow fields from swimming American eels, Anguilla rostrata, measured using particle image velocimetry (PIV) and high-speed video. Eels balance thrust and drag quite evenly, resulting in virtually no wake momentum in the swimming (axial) direction. On average, their wakes resemble those of self-propelled jet propulsors, which have been studied extensively. Theoretical studies of such wakes may provide methods for the estimation of thrust separately from drag. These flow fields are compared with those measured in the wakes of rainbow trout, Oncorhynchus mykiss, and bluegill sunfish, Lepomis macrochirus. In contrast to eels, these fishes produce wakes with axial momentum. Although the net momentum flux must be zero on average, it is neither spatially nor temporally homogeneous; the heterogeneity may provide an alternative route for estimating thrust. This review shows examples of wakes and velocity profiles from the three fishes, indicating challenges in estimating efficiency and power output and suggesting several routes for further experiments. Because these estimates will be complicated, a much simpler method for comparing performance is outlined, using as a point of comparison the power lost producing the wake. This wake power, a component of the efficiency and total power, can be estimated in a straightforward way from the flow

  14. A novel recombinant bivalent outer membrane protein of Vibrio vulnificus and Aeromonas hydrophila as a vaccine antigen of American eel (Anguilla rostrata).

    PubMed

    SongLin, Guo; PanPan, Lu; JianJun, Feng; JinPing, Zhao; Peng, Lin; LiHua, Duan

    2015-04-01

    The immogenicity of a novel vaccine antigen was evaluated after immunized American eels (Anguilla rostrata) with a recombinant bivalent expressed outer membrane protein (OMP) of Vibrio vulnificus and Aeromonas hydrophila. Three groups of eels were intraperitoneal (i.p) injected with phosphate-buffered saline (PBS group), formaline-killed-whole-cell (FKC) of A. hydrophila and V. vulnificus (FKC group) or the bivalent OMP (OMP group). On 14, 21, 28 and 42 days post-vaccination respectively, proliferation of the whole blood cells, titers of specific antibody and lysozyme activities of experimental eels were detected. On 28 day post-vaccination, eels from three groups were challenged by i.p injection of live A. hydrophila or V. vulnificus. The results showed that, compared with the PBS group, proliferation of whole blood cells in OMP group was significant enhanced on 28 days, and the serum titers of anti-A.hydrophila and anti-V. vulnificus antibody in eels of FKC and OMP group were significant increased on 14, 21 and 28d. Lysozyme Activities in serum, skin mucus, liver and kidney were significant changed between the three groups. Relative Percent Survival (RPS) after challenged A. hydrophila in KFC vs. PBS group and OMP vs. PBS group were 62.5% and 50% respectively, and the RPS challenged V. vulnificus in FKC and OMP vs. PBS group were 37.5% and 50% respectively. These results suggest that American eels immunized with the bivalent OMP would positively affect specific as well as non-specific immune parameters and protect against infection by the two pathogens in fresh water farming. PMID:25655329

  15. EELS study of niobium carbo-nitride nano-precipitates in ferrite.

    PubMed

    Courtois, E; Epicier, T; Scott, C

    2006-01-01

    Micro-alloying steels allow higher strength to be achieved, with lower carbon contents, without a loss in toughness, weldability or formability through the generation of a fine ferrite grain size with additional strengthening being provided by the fine scale precipitation of complex carbo-nitride particles. Niobium is reported to be the most efficient micro-alloying element to achieve refinement of the final grain structure. A detailed microscopic investigation is one of the keys for understanding the first stages of the precipitation sequence, thus transmission electron microscopy (TEM) is required. Model Fe-(Nb,C) and Fe-(Nb,C,N) ferritic alloys have been studied after annealing under isothermal conditions. However the nanometre scale dimensions of the particles makes their detection, structural and chemical characterization delicate. Various imaging techniques have then been employed. Conventional TEM (CTEM) and high resolution TEM (HRTEM) were used to characterise the morphology, nature and repartition of precipitates. Volume fractions and a statistical approach to particle size distributions of precipitates have been investigated by energy filtered TEM (EFTEM) and high angle annular dark field (HAADF) imaging. Great attention was paid to the chemical analysis of precipitates; their composition has been quantified by electron energy loss spectroscopy (EELS), on the basis of calibrated 'jump-ratios' of C-K and N-K edges over the Nb-M edge, using standards of well-defined compositions. It is shown that a significant addition of nitrogen in the alloy leads to a complex precipitation sequence, with the co-existence of two populations of particles: pure nitrides and homogeneous carbo-nitrides respectively. PMID:16500107

  16. Effect of sperm cryopreservation on the European eel sperm viability and spermatozoa morphology.

    PubMed

    Asturiano, J F; Marco-Jiménez, F; Peñaranda, D S; Garzón, D L; Pérez, L; Vicente, J S; Jover, M

    2007-04-01

    The main objective of the present work was to study the effect of cryopreservation of European eel sperm both on the sperm viability and the spermatozoa head morphology. Spermatozoa morphology was evaluated with computer-assisted morphology analysis after collection in fresh samples, after adding the freezing medium containing dimethyl sulfoxide as cryoprotectant and, finally, after the cryopreservation process and thawing. Cell viability was assessed, in both fresh and thawed samples, by Hoechst 33258 staining. Computer-assisted sperm analysis (CASA) was used to determine the percentage of motile cells and to measure motility parameters in sperm samples. A significant decrease of head perimeter (12.56%) and area (17.90%) was detected from spermatozoa in fresh to thawed samples, indicating that cells do not recover the original size after the cryopreservation process. CASA was used to measure the percentage of motile cells (51.9%) and spermatozoa motility parameters such as curvilinear, straight line and angular path velocities, as well as beating cross frequency. This technique was employed in the fresh sperm samples but proteins present at the freezing medium (L-alpha-phosphatidylcholine) made impossible to use this last technique in thawed samples. When sperm viability was assessed by Hoechst staining, a significant decrease of approximately 15% (73.10 vs 58.26%) of alive spermatozoa was registered from fresh to thawed samples. The percentage of motile cells measured by CASA in fresh samples (51.9%) was lower than the percentage of alive cells determined by Hoechst stainning, suggesting the existence of different batches of spermatozoa in different stages of development, even during the eight to tenth weeks of treatment, when the highest sperm quality was found. PMID:17348973

  17. Structure and geologic history of late Cenozoic Eel River basin, California

    SciTech Connect

    Clarke, S.H. Jr.

    1988-03-01

    The Eel River basin formed as a late Cenozoic forearc basin floored by late Mesozoic and early Cenozoic allochthonous terranes (central and coastal belts of the Franciscan complex). Regionally, basement rocks are unconformably overlain on land by a sedimentary sequence as much as about 4200 m thick that comprises the Bear River Formation (early and middle Miocene) and the Wildcat Group (late Miocene to middle Pleistocene) and offshore by broadly coeval upper Tertiary and Quaternary deposits as much as 3300 m thick. Offshore, the southern part of the basin is typified by the seaward extensions of youthful northeast-dipping thrust and reverse faults and northwest-trending anticlines. The latest period of deformation in this part of the basin began during the middle Pleistocene and probably reflects north-northwestward migration of the Mendocino triple junction and encroachment of the Pacific plate. Farther north, the western basin margin and adjacent upper continental slope are separated from the axial part of the offshore basin by a narrow zone of north-northwest-trending, right-stepping en echelon folds. These folds indicate that northeast-southwest compression characteristic of the southern part of the basin is accompanied toward the north by right-lateral shear between the accretionary complex to the west and the basin to the east. The northeastern margin of the offshore basin is cut by north to north-northwest-trending high-angle reverse faults that vertically offset basement rocks as much as 1300 m, west side down. These faults, which may merge northward, coincide with older terrane boundaries and locally show evidence of late Cenozoic reactivation with possible right-lateral slip.

  18. Silver Trees: Chemistry on a TEM Grid

    EPA Science Inventory

    The copper/carbon substrate of a TEM grid reacted with aqueous silver nitrate solution within minutes to yield spectacular tree-like silver dendrites, without using any added capping or reducing reagents. These results demonstrate a facile, aqueous, room temperature synthesis of...

  19. Intravesical silver nitrate for refractory hemorrhagic cystitis

    PubMed Central

    Montgomery, Brian D.; Boorjian, Stephen A.; Ziegelmann, Matthew J.; Joyce, Daniel D.; Linder, Brian J.

    2016-01-01

    Objective Hemorrhagic cystitis is a challenging clinical entity with limited evidence available to guide treatment. The use of intravesical silver nitrate has been reported, though supporting literature is sparse. Here, we sought to assess outcomes of patients treated with intravesical silver nitrate for refractory hemorrhagic cystitis. Material and methods We identified nine patients with refractory hemorrhagic cystitis treated at our institution with intravesical silver nitrate between 2000–2015. All patients had failed previous continuous bladder irrigation with normal saline and clot evacuation. Treatment success was defined as requiring no additional therapy beyond normal saline irrigation after silver nitrate instillation prior to hospital discharge. Results Median patient age was 80 years (IQR 73, 82). Radiation was the most common etiology for hemorrhagic cystitis 89% (8/9). Two patients underwent high dose (0.1%–0.4%) silver nitrate under anesthesia, while the remaining seven were treated with doses from 0.01% to 0.1% via continuous bladder irrigation for a median of 3 days (range 2–4). All nine patients (100%) had persistent hematuria despite intravesical silver nitrate therapy, requiring additional interventions and red blood cell transfusion during the hospitalization. There were no identified complications related to intravesical silver nitrate instillation. Conclusion Although well tolerated, we found that intravesical silver nitrate was ineffective for bleeding control, suggesting a limited role for this agent in the management of patients with hemorrhagic cystitis.

  20. Preliminary Silver-hydrogen Cell Test Results

    NASA Technical Reports Server (NTRS)

    Lurie, C.

    1984-01-01

    Silver-hydrogen cells were tested. The objective of the test was to estimate useful life by operation at accelerated, simulated geosynchronous orbit conditions. Ten simulated seasons were run and are summarized. The results to-date reflect stable, trouble-free performance and indicate that the silver-hydrogen couple shows promise as a lightweight alternative to the nickel systems.