Are Bacterio- and Phytoplankton Community Compositions Related in Lakes Differing in Their Cyanobacteria Contribution and Physico-Chemical Properties?
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ABSTRACT:
SUBMITTER: Kokocinski M
PROVIDER: S-EPMC8227929 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundThe Azores are oceanic islands located in the Northern Atlantic Ocean and are particularly rich in aquatic systems, ranging from freshwater, brackish, marine and thermal habitats. Due to the increase in local anthropogenic pressures and global warming, several azorean lakes began to reveal signs of eutrophication that led to the implementation of monitoring programmes and management strategies on the most impacted lakes. Later, the Water Framework Directive (2000/60/EC) demanded the establishment of biomonitoring programmes for European freshwater ecosystems and the limited Azorean monitoring programmes were extended to a larger set of lakes. Since the establishment of the aquatic systems monitoring programme in the Azores archipelago, lakes have been regularly sampled, producing innumerous unpublished records of cyanobacteria that are difficult to access.New informationHere we present the occurrences of cyanobacteria in Azorean lakes that result from 22 years of phytoplankton monitoring in a total of 1948 cyanobacteria occurrences from 968 phytoplankton sampling events on Azorean lakes done between 1996 and 2018 as part of regional inland aquatic ecosystems monitoring programmes. Forty two cyanobacteria taxa were identified in those events, 28 species and 14 at genus level. This information is crucial for conservation, biodiversity studies and lake management, as some of the cyanobacteria species present are bloom-forming and have the ability to produce toxins. This will also allow for the identification of invasive species and possible targeted control and mitigation programmes, according to the species present in the Azorean lakes.
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Project description:PurposeIt is hypothesized that sodium acetate (SA) can be used for in situ coating of drug loaded chitosan NPs for improved physico-chemical properties.MethodsTenofovir (TFV) is used as a model drug. Uncoated chitosan NPs are prepared by ionic gelation. SA is generated in situ from half neutralization of acetic acid with sodium hydroxide, and coats chitosan NPs during freeze-drying. The NPs' physico-chemical properties [e.g., particle mean diameters (PMD) zeta potential (ζ), EE%, drug release profile, morphology] are characterized by dynamic light scattering, spectrophotometry, Korsmeyer-Peppas model, transmission electron microscopy (TEM), respectively. Melting point (MP), non-aqueous titration, Fourier transform infrared (FTIR) analysis, and powder X-ray diffractometry (XRD) pattern evaluate the SA coated chitosan NPs. The NPs' cytotoxicity on macrophages Raw 264.7 is assessed by neutral red, resazurin, nitrite oxide (NO) and cytokines assays.ResultsCollectively, FTIR, ζ, XRD, MP, and TEM data confirm that SA coats chitosan NPs. The PMD range is 136-348 nm (uncoated) and 171-379 nm (coated NPs). The ζ values range is +24.3-28.5 mV (uncoated) and 0.1-3.1 mV (coated NPs). The EE% ranges from 5.5 to 11.7% (uncoated NPs) and increased up to 86.3-92.7%(8-17-fold) after coating. The SA also prevents NPs aggregation during the freeze-drying and aqueous dispersion. The core-shell NPs exhibited a sustain release of TFV following anomalous transport mechanism (R(2) ~ 0.99). The coated NPs are non-cytotoxic (cell viability ~100%) and without any proinflammatory response.ConclusionsThis SA coating chitosan NPs mechanism may be useful for (i) efficient encapsulation, (ii) stabilizing colloidal dispersions, (iii) controlling the release and solubility of bioactive agents.
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