| 51761. |
- Meynet, Paola, et al.
(författare)
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Effect of activated carbon amendment on bacterial community structure and functions in a pah impacted urban soil
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:9, s. 5057-5066
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Tidskriftsartikel (refereegranskat)abstract
- We collected urban soil samples impacted by polycyclic aromatic hydrocarbons (PAHs) from a sorbent-based remediation field trial to address concerns about unwanted side-effects of 2% powdered (PAC) or granular (GAC) activated carbon amendment on soil microbiology and pollutant biodegradation. After three years, total microbial cell counts and respiration rates were highest in the GAC amended soil. The predominant bacterial community structure derived from denaturing gradient gel electrophoresis (DGGE) shifted more strongly with time than in response to AC amendment. DGGE band sequencing revealed the presence of taxa with closest affiliations either to known PAR degraders, e.g. Rhodococcus jostii RHA-1, or taxa known to harbor PAR degraders, e.g. Rhodococcus erythropolis, in all soils. Quantification by real-time polymerase chain reaction yielded similar dioxygenases gene copy numbers in unamended, PAC-, or GAC-amended soil. PAH availability assessments in batch tests showed the greatest difference of 75% with and without biocide addition for unamended soil, while the lowest PAH availability overall was measured in PAC-amended, live soil. We conclude that AC had no detrimental effects on soil microbiology, AC-amended soils retained the potential to biodegrade PAHs, but the removal of a available pollutants by biodegradation was most notable in unamended soil.
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| 51762. |
- Meysick, L., et al.
(författare)
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Coastal ecosystem engineers and their impact on sediment dynamics: Eelgrass–bivalve interactions under wave exposure
- 2022
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Ingår i: Limnology and Oceanography. - : Wiley. - 1939-5590 .- 0024-3590. ; 67:3, s. 621-633
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Tidskriftsartikel (refereegranskat)abstract
- Habitat forming ecosystem engineers play critical roles in structuring coastal seascapes. Many ecosystem engineers, such as seagrasses and epifaunal bivalves, are known to have positive effects on sediment stability and increase coastal protection and ecosystem resilience. Others, such as bioturbating infaunal bivalves, may instead destabilize sediment. However, despite the common co-occurrence of seagrasses and bivalves in coastal seascapes, little is known of their combined effects on sediment dynamics. Here, we used wave flumes to compare sediment dynamics in monospecific and multispecific treatments of eelgrass, Zostera marina, and associated bivalves (infaunal Limecola balthica, infaunal Cerastoderma edule, epifaunal Magellana gigas) under a range of wave exposures. Eelgrass reduced bedload erosion rates by 25–50%, with digital elevation models indicating that eelgrass affected the sediment micro-bathymetry by decreasing surface roughness and ripple sizes. Effects of bivalves on sediment mobilization were species-specific; L. balthica reduced erosion by 25%, C. edule increased erosion by 40%, while M. gigas had little effect. Importantly, eelgrass modified the impacts of bivalves: the destabilizing effects of C. edule vanished in the presence of eelgrass, while we found positive additive effects of eelgrass and L. balthica on sediment stabilization and potential for mutual anchoring. Such interspecific interactions are likely relevant for habitat patch emergence and resilience to extreme wave conditions. In light of future climate scenarios where increasing storm frequency and wave exposure threaten coastal ecosystems, our results add a mechanistic understanding of sediment dynamics and interactions between ecosystem engineers, with relevance for management and conservation.
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| 51763. |
- Meysick, L., et al.
(författare)
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The influence of hydrodynamics and ecosystem engineers on eelgrass seed trapping
- 2019
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14:9
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Tidskriftsartikel (refereegranskat)abstract
- Propagule dispersal is an integral part of the life cycle of seagrasses; important for colonising unvegetated areas and increasing their spatial distribution. However, to understand recruitment success, seed dispersal and survival in habitats of different complexity remains to be quantified. We tested the single and synergistic effects of three commonly distributed ecosystem engineers-eelgrass (Zostera marina), oysters (Magellana gigas) and blue mussels (Mytilus edulis)-on trapping of Z. marina seeds in a hydraulic flume under currents. Our results suggest that seed retention increases with habitat complexity and further reveal insights into the underlying mechanisms. In eelgrass canopy, trapping occurred mostly through direct blocking of a seed's pathway, while trapping in bivalve patches was mainly related to altered hydrodynamics in the lee side, i.e. behind each specimen. With increasing flow velocity (24-30 cm s(-1) in eelgrass canopy, 18-30 cm s(-1) in bivalve patches), modifications of the sediment surface through increased turbulence and erosive processes became more important and resulted in high seed trapping rates. Furthermore, we show that while monospecific patches of seagrass and bivalves had different trapping optima depending on flow velocities, intermixing resulted in consistently high trapping rates throughout the investigated hydrodynamic gradient. Our results highlight the importance of positive interactions among ecosystem engineers for seed retention and patch emergence in eelgrass.
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| 51764. |
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| 51765. |
- Mezger, Anja, et al.
(författare)
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A General Method for Rapid Determination of Antibiotic Susceptibility and Species in Bacterial Infections
- 2015
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 53:2, s. 425-432
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Tidskriftsartikel (refereegranskat)abstract
- To ensure correct antibiotic treatment and reduce the unnecessary use of antibiotics, there is an urgent need for new rapid methods for species identification and determination of antibiotic susceptibility in infectious pathogenic bacteria. We have developed a general method for the rapid identification of the bacterial species causing an infection and the determination of their antibiotic susceptibility profiles. An initial short cultivation step in the absence and presence of different antibiotics was combined with sensitive species-specific padlock probe detection of the bacterial target DNA to allow a determination of growth (i.e., resistance) and no growth (i.e., susceptibility). A proof-of-concept was established for urinary tract infections in which we applied the method to determine the antibiotic susceptibility profiles of Escherichia coli for two drugs with 100% accuracy in 3.5 h. The short assay time from sample to readout enables fast appropriate treatment with effective drugs and minimizes the need to prescribe broad-spectrum antibiotics due to unknown resistance profiles of the treated infection.
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| 51766. |
- Mezhzherin, Sergey, V, et al.
(författare)
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Cryptic expansion of hybrid polyploid spined loaches Cobitis in the rivers of Eastern Europe
- 2022
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Ingår i: Hydrobiologia. - : Springer Nature. - 0018-8158 .- 1573-5117. ; 849:7, s. 1689-1700
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Tidskriftsartikel (refereegranskat)abstract
- An expansion of a species range may happen unnoticed when an expanding species is similar in appearance to local species and distinguishable mainly by genetic methods. The morphological similarity of polyploid spined loaches of the hybrid complex Cobitis elongatoides-taenia-tanaitica with their diploid relatives makes their recent expansion in the rivers of Eastern Europe truly cryptic. We confirm this expansion and describe it in space and time by analyzing 20 museum collections from 1928 to 1985 and 92 recent sampling points from the Danube, Dniester, Southern Bug, Dnieper, Donets, and coastal rivers of the Sea of Azov. According to the museum collections, the numerical increase of polyploids relative to diploids occurred in the 1960-1980s that coincides with the time of intensive hydraulic construction when a series of reservoirs were created in the Middle Dnieper basin. Our sampling during 2000-2020 suggests that the trend toward the numerical increase of polyploids also continues in the twenty-first century. This expansion could have occurred under new ecological conditions, both due to the few clonal individuals that spread into the rivers of Eastern Europe as a result of postglacial recolonization, and due to invasions of polyploids from the Danube, Vistula, and Oder basins in the middle of the twentieth century. The expansion of polyploids is probably a consequence of their relatively high fitness in comparison with diploids in conditions of significant anthropogenization of river systems.
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| 51767. |
- Meziane, El Kahina, et al.
(författare)
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Bi-Functional Chicken Immunoglobulin-Like Receptors With a Single Extracellular Domain (ChIR-AB1): Potential Framework Genes Among a Relatively Stable Number of Genes Per Haplotype
- 2019
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Ingår i: Frontiers in Immunology. - : FRONTIERS MEDIA SA. - 1664-3224. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The leukocyte receptor complex (LRC) in humans encodes many receptors with immunoglobulin-like (Ig-like) extracellular domains, including the killer Ig-like receptors (KIRs) expressed on natural killer (NK) cells among others, the leukocyte Ig-like receptors (LILRs) expressed on myeloid and B cells, and an Fc receptor (FcR), all of which have important roles in the immune response. These highly-related genes encode activating receptors with positively-charged residues in the transmembrane region, inhibitory receptors with immuno-tyrosine based motifs (ITIMs) in the cytoplasmic tail, and bi-functional receptors with both. The related chicken Ig-like receptors (ChIRs) are almost all found together on a microchromosome, with over 100 activating (A), inhibitory (B), and bi-functional (AB) genes, bearing either one or two extracellular Ig-like domains, interspersed over 500-1,000 kB in the genome of an individual chicken. Sequencing studies have suggested rapid divergence and little overlap between ChIR haplotypes, so we wished to begin to understand their genetics. We chose to use a hybridization technique, reference strand-mediated conformational analysis (RSCA), to examine the ChIR-AB1 family, with a moderate number of genes dispersed across the microchromosome. Using fluorescently-labeled references (FLR), we found that RSCA and sequencing of ChIR-AB1 extracellular exon gave two groups of peaks with mobility correlated with sequence relationship to the FLR. We used this system to examine widely-used and well-characterized experimental chicken lines, finding only one or a few simple ChIR haplotypes for each line, with similar numbers of peaks overall. We found much more complicated patterns from a broiler line from a commercial breeder and a flock of red junglefowl, but trios of parents and offspring from another commercial chicken line show that the complicated patterns are due to heterozygosity, indicating a relatively stable number of peaks within haplotypes of these birds. Some ChIR-AB1 peaks were found in all individuals from the commercial lines, and some of these were shared with red junglefowl and the experimental lines derived originally from egg-laying chickens. Overall, this analysis suggests that there are some simple features underlying the apparent complexity of the ChIR locus.
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| 51768. |
- Mgbeahuruike, Anthony Christian, et al.
(författare)
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Reduction of the Adverse Impacts of Fungal Mycotoxin on Proximate Composition of Feed and Growth Performance in Broilers by Combined Adsorbents
- 2021
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Ingår i: Toxins. - : MDPI AG. - 2072-6651. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Synergistic interaction of adsorbents in reducing the adverse impacts of mycotoxin on performance and proximate composition of broiler feeds was investigated. Fungal growth was induced by sprinkling water on the feed. S. cerevisiae + bentonite, kaolin + bentonite or S. cerevisiea + kaolin adsorbent combinations (1.5 g/kg feed) were added and the feeds were stored in black polythene bags. An untreated group was kept as a positive control while fresh uncontaminated feed was used as a negative control. Mycotoxins were extracted from the feeds and quantified using reverse phase HPLC. Proximate composition, nutrient digestibility of the feeds, feed intake and weight gain of the broilers were measured. Deoxynivalenol (DON) concentration in the contaminated/untreated feed was 347 mu g/kg while aflatoxin B1 (AFB1) was 34 mu g/kg. Addition of bentonite and kaolin in the contaminated feed reduced AFB1 and DON to significantly lower levels. Feed intake and weight gain were low in the broilers fed the contaminated feed. The carbohydrate level was significantly (p < 0.05) reduced from 62.31 to 40.10%, crude protein digestibility dropped from 80.67 to 49.03% in the fresh feed and contaminated feed respectively. Addition of the adsorbents (S. cerevisiae and bentonite) significantly (p < 0.05) improved these parameters.
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| 51769. |
- Mhlanga, L, et al.
(författare)
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Observations on limnological conditions associated with a fish kill of Oreochromis niloticus in Lake Chivero following collapse of an algal bloom
- 2006
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Ingår i: African Journal of Ecology. - : Wiley. - 1365-2028 .- 0141-6707. ; 44:2, s. 199-208
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Tidskriftsartikel (refereegranskat)abstract
- Possible causes of deaths of Oreochromis niloticus in Lake Chivero were examined in relation to changes in limnological conditions monitored over a 25-month period. The fish deaths coincided with the collapse of an algal bloom that had developed and builtup in the lake for 8 months. Chlorophyll a and dissolved oxygen increased to average concentrations of 42.4 mu g l(-1) and 10.9 mg l(-1) respectively prior to the collapse of the bloom. Dissolved oxygen decreased when the bloom started to die off and coincided with the fish deaths when the average surface dissolved oxygen concentration in the lake was 3.9 mg l(-1) and was at a depth of 5 m < 2 mg l(-1). Mortality probably resulted from depressed oxygen levels caused by the high oxygen demand from the massive algal die-off and released algal toxins. This is the first time that die-off of algae has been linked to fish-kills in Lake Chivero as occurs in other hypereutrophic systems.
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| 51770. |
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