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61.
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63.
Effects of Artificial Filamentous Substrate on Zebra Mussel (Dreissena polymorpha) Settlement 总被引:1,自引:0,他引:1
Though a great deal of research focuses on the range expansion and presence of adult zebra mussels, there is still a need
to understand the processes of larval settlement and how that relates to adult populations. There is evidence that marine
bivalves preferentially settle on filamentous substrates such as hydroid colonies and algae; however, similar studies are
rare in freshwater systems. We examined the
importance of filamentous substrate for the settlement of the zebra mussel (Dreissena polymorpha) larvae by deploying PVC settlement plates with and without polypropylene filaments in the Bark River for a 6-week period.
Larval supply was monitored weekly. Our results suggest that artificial filaments facilitated recruitment, primarily by increasing
surface area available for attachment. Mussels on artificial filaments were significantly smaller in size than mussels attached
to filamentous or control plate surfaces, providing some evidence that mussels may detach from filamentous substrate after
initial settlement. This study adds to our general understanding about the role of filamentous substrates in the process of
larval settlement and suggests that substrates colonized by filamentous epibionts may face increased risk of fouling by zebra
mussels.
An erratum to this article is available at . 相似文献
64.
Geneviève Haag Michel Botbol Rozenn Graignic Fernando Perez-Diaz Guillaume Bronsard Solenn Kermarrec Marie-Christine Clement Annick Cukierman Catherine Druon Andrée Duprat Françoise Jardin Anik Maufras du Chatellier Jacqueline Tricaud Simone Urwand Jean-Marc Guilé David Cohen Sylvie Tordjman 《Journal of Physiology》2010,104(6):323-336
The present study was designed to examine the reliability and validity of the Autism Psychodynamic Evaluation of Changes (APEC) scale, developed to assess the evolution in individuals with autism under treatment. The APEC scale focuses on the key role of impairment in body image construction, which requires cross-modal sensory integration through emotional communication with motor representations. Thus, the body image construction is associated simultaneously with spatial and temporal organization and allows the emergence of self- and others-representations. The use of the APEC scale, with its seven domains (expression of emotion in relationships, eye contact, body image, graphic productions, exploration of space and objects, time perception, and verbal language), underlines the importance in autistic disorder of anxieties related to body and spatial representations, and of impairment in the body ego construction which is closely linked to the emergence of individuation/separation processes. This study was conducted on 73 children and adolescents with autistic disorder. They were recruited in day care facilities where two caregivers independently gave their ratings based on their clinical observation on a daily basis during the same month. Analyses included assessing construct validity through correspondence analyses and inter-rater reliability using kappa coefficients. The APEC scale offers a reliable and validated psychodynamic assessment of interest for professionals (such as child psychiatrists, caregivers, therapists or teachers) and researchers working with children, adolescents and adults with autistic disorder, especially in the follow-up of their evolution. The APEC scale provides an approach at the interface of psychoanalysis and neuroscience, and is also of interest for clinical and developmental psychology. Using the APEC scale in a range of different practical and research settings will foster links between psychoanalytic perspectives and educational training for children with autistic disorder, and will contribute to the dialogue between psychoanalysis, neuroscience and psychology. 相似文献
65.
Jacques Renault Aurelie Bernard Solenn Brajeul Pierre Verhaeghe Sabrina Butt Frederic Fabis 《Journal of enzyme inhibition and medicinal chemistry》2013,28(6):577-583
A series of N-ω-aminoalkyl- or N-ω-amidinoalkyl-2,4,6-triisopropyl benzenesulfonamides has been synthesized and their respective affinity indices on 5-HT6 receptor determined. This evaluation clearly showed that the compounds possessing an arylpiperazine moiety or an amidine function exhibited good affinity for the model. 相似文献
66.
Daphnia lumholtzi comprises a substantial component of the zooplankton community during mid‐ to late‐summer in Lake Chautauqua, a floodplain lake along the Illinois River near Havana, Illinois. In order to quantify the utilization of D. lumholtzi by juvenile fishes, diet analyses were conducted for seven juvenile fish species collected from Lake Chautauqua during the 2001 annual drawdown period. Freshwater drum Aplodinotus grunniens and emerald shiner Notropis atherinoides demonstrated negative selectivity for D. lumholtzi relative to native zooplankton species whereas four species of fish (bluegill Lepomis macrochirus, white bass Morone chrysops, white crappie Pomoxis annularis and black crappie Pomoxis nigromaculatus) consumed substantial amounts of D. lumholtzi. Although selectivity values for D. lumholtzi varied among these fish species, positive selection for D. lumholtzi increased similarly among larger size classes of each fish species, and corresponded with ontogenetic shifts in diet. Mean body length of D. lumholtzi consumed by 20–69 mm LT juvenile fishes ranged from 0·75 to 0·99 mm with a calculated total length range of 2·0–2·6 mm. Results from this study provide evidence that high abundances of D. lumholtzi in mid‐ to late‐summer provide an additional food source for several juvenile fish species during a time when abundances of large native cladoceran species (i.e. Daphnia) are low, and juvenile fishes are searching for larger prey associated with ontogenetic shifts from zooplankton to macroinvertebrates and fishes. Because zooplankton production is typically lower in rivers than in lakes, survivorship of juvenile fishes produced in floodplain lakes may be higher in riverine systems if they are not reliant on zooplankton as a primary food resource. Therefore, high abundances of D. lumholtzi may benefit juvenile fishes in managed floodplain lakes, such as Lake Chautauqua, by increasing growth and facilitating the transition from zooplanktivory to insectivory or piscivory. 相似文献
67.
Hybridization between two cryptic filamentous brown seaweeds along the shore: analysing pre‐ and postzygotic barriers in populations of individuals with varying ploidy levels 下载免费PDF全文
Alejandro E. Montecinos Marie‐Laure Guillemin Lucia Couceiro Akira F. Peters Solenn Stoeckel Myriam Valero 《Molecular ecology》2017,26(13):3497-3512
We aimed to study the importance of hybridization between two cryptic species of the genus Ectocarpus, a group of filamentous algae with haploid–diploid life cycles that include the principal genetic model organism for the brown algae. In haploid–diploid species, the genetic structure of the two phases of the life cycle can be analysed separately in natural populations. Such life cycles provide a unique opportunity to estimate the frequency of hybrid genotypes in diploid sporophytes and meiotic recombinant genotypes in haploid gametophytes allowing the effects of reproductive barriers preventing fertilization or preventing meiosis to be untangle. The level of hybridization between E. siliculosus and E. crouaniorum was quantified along the European coast. Clonal cultures (568 diploid, 336 haploid) isolated from field samples were genotyped using cytoplasmic and nuclear markers to estimate the frequency of hybrid genotypes in diploids and recombinant haploids. We identified admixed individuals using microsatellite loci, classical assignment methods and a newly developed Bayesian method (XPloidAssignment), which allows the analysis of populations that exhibit variations in ploidy level. Over all populations, the level of hybridization was estimated at 8.7%. Hybrids were exclusively observed in sympatric populations. More than 98% of hybrids were diploids (40% of which showed signs of aneuploidy) with a high frequency of rare alleles. The near absence of haploid recombinant hybrids demonstrates that the reproductive barriers are mostly postzygotic and suggests that abnormal chromosome segregation during meiosis following hybridization of species with different genome sizes could be a major cause of interspecific incompatibility in this system. 相似文献
68.
In this paper, we investigated the genetic structure and distribution of allelic frequencies at the gametophytic self-incompatibility locus in three populations of Prunus avium L. In line with theoretical predictions under balancing selection, genetic structure at the self-incompatibility locus was almost three times lower than at seven unlinked microsatellites. Furthermore, we found that S-allele frequencies in wild cherry populations departed significantly from the expected isoplethic distribution towards which balancing selection is expected to drive allelic frequencies (i.e. identical frequency equal to the inverse of the number of alleles in the population). To assess whether this departure could be caused either by drift alone or by population structure, we used numerical simulations to compare our observations with allelic frequency distributions expected : (1) within a single deme from a subdivided population with various levels of differentiation; and (2) within a finite panmictic population with identical allelic diversity. We also investigated the effects of sample size and degree of population structure on tests of departure from isoplethic equilibrium. Overall, our results showed that the observed allele frequency distributions were consistent with a model of subdivided population with demes linked by moderate migration rate. 相似文献
69.
Odd G Brakstad Mimmi Throne-Holst Roman Netzer Donald M Stoeckel Ronald M Atlas 《Microbial biotechnology》2015,8(6):989-998
The Deepwater Horizon (DWH) accident in 2010 created a deepwater plume of small oil droplets from a deepwater well in the Mississippi Canyon lease block 252 (‘Macondo oil’). A novel laboratory system was used in the current study to investigate biodegradation of Macondo oil dispersions (10 μm or 30 μm median droplet sizes) at low oil concentrations (2 mg l−1) in coastal Norwegian seawater at a temperature of 4–5°C. Whole metagenome analyses showed that oil biodegradation was associated with the successive increased abundances of Gammaproteobacteria, while Alphaproteobacteria (Pelagibacter) became dominant at the end of the experiment. Colwellia and Oceanospirillales were related to n-alkane biodegradation, while particularly Cycloclasticus and Marinobacter were associated with degradation of aromatic hydrocarbons (HCs). The larger oil droplet dispersions resulted in delayed sequential changes of Oceanospirillales and Cycloclasticus, related with slower degradation of alkanes and aromatic HCs. The bacterial successions associated with oil biodegradation showed both similarities and differences when compared with the results from DWH field samples and laboratory studies performed with deepwater from the Gulf of Mexico. 相似文献
70.
Summary Plasmalemmal ionic currents from excitable motor cells of the primary pulvinus ofMimosa pudica were investigated by patch-clamp techniques. In almost all of the enzymatically isolated protoplasts, a delayed rectifier potassium current was activated by depolarization, while no currents were detected upon hyperpolarization. This sustained outward current was reversibly blocked by Ba and TEA and serves to repolarize the membrane potential. Outward single channel currents that very likely underly the macroscopic outward potassium current had an elementary conductance of 20 pS. In addition, in a few protoplasts held at hyperpolarized potentials, depolarization-activated transient inward currents were observed, and under current clamp, action potential-like responses were triggered by depolarizing current injections or by mechanical perturbations. The activation characteristics of both inward currents and spikes showed striking similarities compared to those of action potentialsin situ. 相似文献