Novel members of the family Flavobacteriaceae from Antarctic maritime habitats including Subsaximicrobium wynnwilliamsii gen. nov., sp. nov., Subsaximicrobium saxinquilinus sp. nov., Subsaxibacter broadyi gen. nov., sp. nov., Lacinutrix copepodicola gen. nov., sp. nov., and novel species of the genera Bizionia, Gelidibacter and Gillisia.
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Several orange- and yellow-pigmented, halophilic, strictly aerobic, chemoheterotrophic, Gram-negative strains were isolated during investigations of maritime Antarctic habitats, including coastal fast sea-ice brine and algae, crustaceans and quartz stone sublithic cyanobacterial biofilms. Isolates investigated in this study belonged to the marine clade of the family Flavobacteriaceae and represented lineages that were either distinct from species with validly published names or appeared to be distinct species within existing genera. A polyphasic taxonomic analysis demonstrated the novelty of these strains, and several new taxa are proposed. Strains from quartz stone sublithic communities were grouped into two new genera designated Subsaximicrobium gen. nov. and Subsaxibacter gen. nov. The genus Subsaximicrobium included the species Subsaximicrobium wynnwilliamsii sp. nov. (type species; type strain G#7(T)=ACAM 1070(T)=CIP 108525(T)) and Subsaximicrobium saxinquilinus sp. nov. (type strain Y4-5(T)=ACAM 1063(T)=CIP 108526(T)). The genus Subsaxibacter contained a single species designated Subsaxibacter broadyi sp. nov. (type strain P7(T)=ACAM 1064(T)=CIP 108527(T)). A novel bacterial strain isolated from the lake-dwelling, calanoid copepod Paralabidocera antarctica was given the name Lacinutrix copepodicola gen. nov., sp. nov. (type strain DJ3(T)=ACAM 1055(T)=CIP 108538(T)). Four novel species of the genus Bizionia were discovered, Bizionia algoritergicola sp. nov. (type strain APA-1(T)=ACAM 1056(T)=CIP 108533(T)) and Bizionia myxarmorum sp. nov. (type strain ADA-4(T)=ACAM 1058(T)=CIP 108535(T)), which were isolated from the carapace surfaces of sea-ice algae-feeding amphipods, and Bizionia gelidisalsuginis sp. nov. (type strain IC164(T)=ACAM 1057(T)=CIP 108536(T)) and Bizionia saleffrena sp. nov. (type strain HFD(T)=ACAM 1059(T)=CIP 108534(T)), which were isolated from sea-ice brines. Several other novel species were also isolated from sea-ice samples, including two novel species of the genus Gelidibacter, Gelidibacter gilvus sp. nov. (type strain IC158(T)=ACAM 1054(T)=CIP 108531(T)) and Gelidibacter salicanalis sp. nov. (type strain IC162(T)=ACAM 1053(T)=CIP 108532(T)), as well as three novel species of the genus Gillisia, Gillisia illustrilutea sp. nov. (type strain IC157(T)=ACAM 1062(T)=CIP 108530(T)), Gillisia sandarakina sp. nov. (type strain IC148(T)=ACAM 1060(T)=CIP 108529(T)) and Gillisia hiemivivida sp. nov. (type strain IC154(T)=ACAM 1061(T)=CIP 108528(T)). (+info)
Metabolic responses to cold in subterranean crustaceans.
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Changes in polyol, sugar and free amino acid (FAA) body contents were investigated in the aquatic, subterranean (i.e. hypogean) crustaceans Niphargus rhenorhodanensis and Niphargus virei and in a morphologically close aquatic, surface-dwelling (i.e. epigean) crustacean Gammarus fossarum acclimated to 12 degrees C, 3 degrees C and -2 degrees C. With decreasing temperature, G. fossarum significantly increased its alanine and glutamine levels, while trehalose body content was found to increase above control levels only at -2 degrees C. N. virei showed moderate increases of alanine and glycine, and no change in trehalose level was observed in this species. By contrast, N. rhenorhodanensis was the only species showing a significant rise in its total FAA pool, mainly explained by alanine, glycine, arginine and glutamine accumulations. This species also gradually increased its trehalose body content with decreasing temperature. Several cold-hardy ectotherms show metabolic responses to cold that are identical to those observed in N. rhenorhodanensis. A previous comparative study showed that the hypogean N. rhenorhodanensis exhibited a survival time (Lt50) at -2 degrees C that was 26.3 times and 2.6 times higher than the hypogean N. virei and the epigean G. fossarum, respectively. Thus, crustacean levels of FAA and trehalose were correlated with their respective cold tolerances. Such differences in metabolic responses to cold in both hypogean organisms were unexpected since they both live in thermally buffered biotopes. Considering the current distribution areas of the two subterranean crustaceans studied, we assume that the cold hardiness found in the hypogean N. rhenorhodanensis could be correlated with its biogeography history during the quaternary glaciations. (+info)
Moon orientation in adult and young sandhoppers under artificial light.
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Our experiments, carried out at night and during the day on adults and laboratory-born young of the sandhopper Talitrus saltator, deal with the identification and use of the moon as an orientating factor. Sandhoppers were released in an apparatus (a Plexiglas dome) that produced a scenario similar to the natural one (with artificial sky, moon or sun illuminated at different intensities). When tested at night, the adult and young sandhoppers used the artificial moon like the natural one, independently of the intensity of illumination of the artificial sky and moon. In other words, sandhoppers tested at night always identified the artificial moon as the moon and never as the sun. In daytime releases, the seaward orientation failed at low intensities of artificial sky and sun illumination (3.07 and 1.55 microW cm2, respectively), whereas the sun compass was used effectively at higher levels of artificial sun and sky illumination. The innate ability of moon compass orientation in inexpert young sandhoppers was demonstrated even under artificial light. (+info)
Conflict between parasites with different transmission strategies infecting an amphipod host.
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Competition between parasites within a host can influence the evolution of parasite virulence and host resistance, but few studies examine the effects of unrelated parasites with conflicting transmission strategies infecting the same host. Vertically transmitted (VT) parasites, transmitted from mother to offspring, are in conflict with virulent, horizontally transmitted (HT) parasites, because healthy hosts are necessary to maximize VT parasite fitness. Resolution of the conflict between these parasites should lead to the evolution of one of two strategies: avoidance, or sabotage of HT parasite virulence by the VT parasite. We investigated two co-infecting parasites in the amphipod host, Gammarus roeseli: VT microsporidia have little effect on host fitness, but acanthocephala modify host behaviour, increasing the probability that the amphipod is predated by the acanthocephalan's definitive host. We found evidence for sabotage: the behavioural manipulation induced by the Acanthocephala Polymorphus minutus was weaker in hosts also infected by the microsporidia Dictyocoela sp. (roeselum) compared to hosts infected by P. minutus alone. Such conflicts may explain a significant portion of the variation generally observed in behavioural measures, and since VT parasites are ubiquitous in invertebrates, often passing undetected, conflict via transmission may be of great importance in the study of host-parasite relationships. (+info)
Use of carboxylesterase activity to remove pyrethroid-associated toxicity to Ceriodaphnia dubia and Hyalella azteca in toxicity identification evaluations.
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Increases in the use and application of pyrethroid insecticides have resulted in concern regarding potential effects on aquatic ecosystems. Methods for the detection of pyrethroids in receiving waters are required to monitor environmental levels of these insecticides. One method employed for the identification of causes of toxicity in aquatic samples is the toxicity identification evaluation (TIE); however, current TIE protocols do not include specific methods for pyrethroid detection. Recent work identified carboxylesterase treatment as a useful method for removing/detecting pyrethroid-associated toxicity. The present study has extended this earlier work and examined the ability of carboxylesterase activity to remove permethrin- and bifenthrin-associated toxicity to Ceriodaphnia dubia and Hyalella azteca in a variety of matrices, including laboratory water, Sacramento River (CA, USA) water, and Salinas River (CA, USA) interstitial water. Esterase activity successfully removed 1,000 ng/L of permethrin-associated toxicity and 600 ng/L of bifenthrin-associated toxicity to C. dubia in Sacramento River water. In interstitial water, 200 ng/L of permethrin-associated toxicity and 60 ng/L of bifenthrin-associated toxicity to H. azteca were removed. The selectivity of the method was validated using heat-inactivated enzyme and bovine serum albumin, demonstrating that catalytically active esterase is required. Further studies showed that the enzyme is not significantly inhibited by metals. Matrix effects on esterase activity were examined with municipal effluent and seawater in addition to the matrices discussed above. Results confirmed that the esterase retains catalytic function in a diverse array of matrices, suggesting that this technique can be adapted to a variety of aquatic samples. These data demonstrate the utility of carboxylesterase treatment as a viable step to detect the presence of pyrethroids in receiving waters. (+info)
Molecular detection of Hematodinium spp. in Norway lobster Nephrops norvegicus and other crustaceans.
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The Norway lobster Nephrops norvegicus (L.) from the coastal waters of Scotland is seasonally infected by a parasitic dinoflagellate of the genus Hematodinium. Methods used to detect infection include a morphological index (pleopod diagnosis) and several immunoassays. The present study describes the development and application of a set of Hematodinium-specific polymerase chain reaction (PCR) primers and DNA probes based on Hematodinium ribosomal DNA (rDNA). In the PCR assay, a diagnostic band of 380 bp was consistently amplified from total genomic DNA isolated from Hematodinium-infected N. norvegicus. The sensitivity of the assay was 1 ng DNA, which is equivalent to 0.6 parasites. The primer pair also detected Hematodinium DNA in preparations of the amphipod Orchomene nanus, indicating that the amphipod may be infected with the same Hematodinium sp. infecting N. norvegicus. DNA probes detected Hematodinium parasites in heart, hepatopancreas and gill tissues from N. norvegicus, and hepatopancreas and gill tissues from Carcinus maenas, confirming Hematodinium infection in the latter. (+info)
Green land and blue sea: a coloured landscape in the orientation of the sandhopper Talitrus saltator (Montagu) (Amphipoda, Talitridae).
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The use of the landscape in the zonal recovery of Talitrus saltator (Montagu) was demonstrated in the past using natural and artificial landscapes. Here we evaluate the importance of colour in the landscape orientation of sandhoppers. Adult individuals of T. saltator were released in a Plexiglas bowl under the sun, with a view of an artificial landscape: a black cardboard strip or a pair of differently coloured filters, each occupying 180 degrees of the horizon. Our results not only confirm the influence of the black and white artificial landscape-based compass cue on the zonal orientation of T. saltator, but also show that vision of a blue and green artificial landscape affects the direction of orientation; in fact, the orientation agreed with the directional indication of the landscape even when it contrasted with the sun compass indication. The same result was obtained with a blue-grey and green-grey landscape, but not with pairs of grey filters. Therefore, in the sandhoppers' visual world, a coloured landscape that matches the prevalent natural field colours greatly contributes to their directional choice. (+info)
Performance-enhancing role of dietary fatty acids in a long-distance migrant shorebird: the semipalmated sandpiper.
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At the end of summer, semipalmated sandpipers (Calidris pusilla) traveling from the Arctic stop in the Bay of Fundy (east coast of Canada) to build large fat reserves before a non-stop flight to South America. During a 2-week stopover, the body mass of this small shorebird is doubled ( approximately 20 g to 40 g) by feeding on a burrowing amphipod, Corophium volutator, that contains unusually high levels of n-3 polyunsaturated fatty acids (PUFA). In mammals, high n-3 PUFA content of membrane phospholipids (PL) is linked to improved exercise performance due to increased membrane fluidity that accelerates transmembrane lipid transport. We hypothesized that dietary n-3 PUFA could be used as a natural ;performance-enhancing substance' by semipalmated sandpipers to prepare their flight muscles for migration. Also, PUFA stored as fuel in neutral lipids (NL) can be mobilized more quickly than saturated fatty acids, but they contain less energy per unit mass. It is therefore unclear whether dietary fatty acids are modified before storage. Birds were collected at various stages of fat loading to examine changes in the composition of tissue PL (membranes) and NL (fuel stores). Results show that dietary n-3 PUFA are incorporated in tissue lipids in less than 2 weeks. During the stopover, the double bond index of muscle PL increases by 25% and the fatty acid profiles of both muscle PL and adipose NL converge with that of the diet. However, >50% of dietary n-3 PUFA are converted to other fatty acids before storage, mainly to oleate (18:1), possibly because monounsaturates offer a compromise between high energy density and ease of mobilization. This study shows that long-distance migrant birds can (1) use natural diets rich in specific lipids to prime flight muscles for endurance exercise, and (2) modify dietary fatty acids before storing them as fuel. (+info)