30 research outputs found
A Mediterranean Alexandrium taylorii (Dinophyceae) Strain Produces Goniodomin A and Lytic Compounds but Not Paralytic Shellfish Toxins
Species of the dinophyte genus Alexandrium are widely distributed and are notorious bloom formers and producers of various potent phycotoxins. The species Alexandrium taylorii is known to form recurrent and dense blooms in the Mediterranean, but its toxin production potential is poorly studied. Here we investigated toxin production potential of a Mediterranean A. taylorii clonal strain by combining state-of-the-art screening for various toxins known to be produced within Alexandrium with a sound morphological and molecular designation of the studied strain. As shown by a detailed thecal plate analysis, morphology of the A. taylorii strain AY7T from the Adriatic Sea conformed with the original species description. Moreover, newly obtained Large Subunit (LSU) and Internal Transcribed Spacers (ITS) rDNA sequences perfectly matched with the majority of other Mediterranean A. taylorii strains from the databases. Based on both ion pair chromatography coupled to post-column derivatization and fluorescence detection (LC-FLD) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis it is shown that A. taylorii AY7T does not produce paralytic shellfish toxins (PST) above a detection limit of ca. 1 fg cell−1, and also lacks any traces of spirolides and gymnodimines. The strain caused cell lysis of protistan species due to poorly characterized lytic compounds, with a density of 185 cells mL−1 causing 50% cell lysis of cryptophyte bioassay target cells (EC50). As shown here for the first time A. taylorii AY7T produced goniodomin A (GDA) at a cellular level of 11.7 pg cell−1. This first report of goniodomin (GD) production of A. taylorii supports the close evolutionary relationship of A. taylorii to other identified GD-producing Alexandrium species. As GD have been causatively linked to fish kills, future studies of Mediterranean A. taylorii blooms should include analysis of GD and should draw attention to potential links to fish kills or other environmental damage
Swimming Euglena respond to confinement with a behavioural change enabling effective crawling
Some euglenids, a family of aquatic unicellular organisms, can develop highly concerted, large-amplitude peristaltic body deformations. This remarkable behaviour has been known for centuries. Yet, its function remains controversial, and is even viewed as a functionless ancestral vestige. Here, by examining swimming Euglena gracilis in environments of controlled crowding and geometry, we show that this behaviour is triggered by confinement. Under these conditions, it allows cells to switch from unviable flagellar swimming to a new and highly robust mode of fast crawling, which can deal with extreme geometric confinement and turn both frictional and hydraulic resistance into propulsive forces. To understand how a single cell can control such an adaptable and robust mode of locomotion, we developed a computational model of the motile apparatus of Euglena cells consisting of an active striated cell envelope. Our modelling shows that gait adaptability does not require specific mechanosensitive feedback but instead can be explained by the mechanical self-regulation of an elastic and extended motor system. Our study thus identifies a locomotory function and the operating principles of the adaptable peristaltic body deformation of Euglena cells
RNA sequencing and de novo assembly of the digestive gland transcriptome in Mytilus galloprovincialis fed with toxinogenic and non-toxic strains of Alexandrium minutum
Background
The Mediterranean mussel Mytilus galloprovincialis is marine bivalve with a relevant
commercial importance as well as a key sentinel organism for the biomonitoring of
environmental pollution. Here we report the RNA sequencing of the mussel digestive gland,
performed with the aim: a) to produce a high quality de novo transcriptome assembly, thus
improving the genetic and molecular knowledge of this organism b) to provide an initial
assessment of the response to paralytic shellfish poisoning (PSP) on a molecular level, in
order to identify possible molecular markers of toxin accumulation.
Results
The comprehensive de novo assembly and annotation of the transcriptome yielded a
collection of 12,079 non-redundant consensus sequences with an average length of 958 bp,
with a high percentage of full-length transcripts. The whole-transcriptome gene expression
study indicated that the accumulation of paralytic toxins produced by the dinoflagellate
Alexandrium minutum over a time span of 5 days scarcely affected gene expression, but the
results need further validation with a greater number of biological samples and naturally
contaminated specimens.
Conclusion
The digestive gland reference transcriptome we produced significantly improves the data
collected from previous sequencing efforts and provides a basic resource for expanding
functional genomics investigations in M. galloprovincialis. Although not conclusive, the
results of the RNA-seq gene expression analysis support the classification of mussels as
bivalves refractory to paralytic shellfish poisoning and point out that the identification
molecular biomarkers of PSP in the digestive gland of this organism is problematic
Asexual reproduction and strobilation of Sanderia malayensis (Scyphozoa, Pelagiidae) in relation to temperature: experimental evidence and implications
Sanderia malayensis is a scyphozoan species present in the Indian and Pacific Oceans, ranging from the Suez Canal to Japan. Although this jellyfish is commonly kept in aquariums around the world, there is a knowledge gap regarding its biology and ecology, especially at the polyp stage. In this study, we tested the asexual reproductive activity of S.malayensis at Three different temperatures: 10, 15 and 20 \ub0C. Results showed significant increases of polyps at 15 \ub0C and 20 \ub0C, and a minimum at 10\ub0C, corresponding with daily budding rates of 6.61\ub1 0.92%, 5.85 \ub1 2.36% and 0.66\ub10.24%, respectively. Moreover, a second experiment was carried out to report about the ability of S. malayensis to prey on Aurelia solida at ephyra stage. Unidirectional predation of S. malayensis ephyrae on A. solida and an absence of inverse predation was observed. These results could give new insights on the potential fitness and survival of this species if it will ever invade the Mediterranean Sea
Kinematics of flagellar swimming in Euglena gracilis: Helical trajectories and flagellar shapes
The flagellar swimming of euglenids, which are propelled by a single anterior flagellum, is characterized by a generalized helical motion. The 3D nature of this swimming motion, which lacks some of the symmetries enjoyed by more common model systems, and the complex flagellar beating shapes that power it make its quantitative description challenging. In this work, we provide a quantitative, 3D, highly resolved reconstruction of the swimming trajectories and flagellar shapes of specimens of Euglena gracilis. We achieved this task by using high-speed 2D image recordings taken with a conventional inverted microscope combined with a precise characterization of the helical motion of the cell body to lift the 2D data to 3D trajectories. The propulsion mechanism is discussed. Our results constitute a basis for future biophysical research on a relatively unexplored type of eukaryotic flagellar movement
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Socio-Economic Analysis, Ecological Impacts and Sustainability of Long Line Mussel-Farming in the Gulf of Trieste
Mussels aquaculture is a relevant activity for the fishery sector of the North
Adriatic. Around 15 km of coastal water of the Gulf of Trieste, Italy, are
used for the mussel long line farming, for a production of about 5000
tonn/year. The aim of this work is to assess sustainability of this activity in
a Ecological-Socio-Economical (ESE) perspective by evaluating the role of
mussels farming in the socio economic system and in the ecological
system. A socio economic analysis has been conducted involving local
stakeholders in meetings, and also by contacting them with bilateral
interviews and questionnaires. Results of questionners, together with
mussels production data declared at the Sanitary authority, and official
economic data, have been used to quantify the economic relevance of the
activity, and problems perceived by local farmers. For the ecological
analysis, we monitored -on monthly basis- mussels growth and water
quality parameters in 6 sites along the gulf. Feeding preference and
faeces/pseudofaeces production, impact on surface sediment ad its
reversibility have been investigated, too. Results have been used to
calibrate a bioenergetic model representing the mussel physiology and
growth in relation to environmental conditions, and the impact of mussel
aquaculture on water column. The integration of the whole set of models
and information will be used to give an evaluation of the ecological
footprint of the activity and as a tool for coastal management.Keywords: Fisheries Economics, Modeling and Economic Theory, Integrated Modeling Approach of Social and Environmental Interactions in Support of Marine Resource ManagementKeywords: Fisheries Economics, Modeling and Economic Theory, Integrated Modeling Approach of Social and Environmental Interactions in Support of Marine Resource Managemen
Reframing Non-Communicable Diseases and Injuries for Equity in the Era of Universal Health Coverage: Findings and Recommendations from the Kenya NCDI Poverty Commission.
Background: Kenya has implemented a robust response to non-communicable diseases and injuries (NCDIs); however, key gaps in health services for NCDIs still exist in the attainment of Universal Health Coverage (UHC). The Kenya Non-Communicable Diseases and Injury (NCDI) Poverty Commission was established to estimate the burden of NCDIs, determine the availability and coverage of health services, prioritize an expanded set of NCDI conditions, and propose cost-effective and equity-promoting interventions to avert the health and economic consequences of NCDIs in Kenya. Methods: Burden of NCDIs in Kenya was determined using desk review of published literature, estimates from the Global Burden of Disease Study, and secondary analysis of local health surveillance data. Secondary analysis of nationally representative surveys was conducted to estimate current availability and coverage of services by socioeconomic status. The Commission then conducted a structured priority setting process to determine priority NCDI conditions and health sector interventions based on published evidence. Findings: There is a large and diverse burden of NCDIs in Kenya, with the majority of disability-adjusted life-years occurring before age of 40. The poorest wealth quintiles experience a substantially higher deaths rate from NCDIs, lower coverage of diagnosis and treatment for NCDIs, and lower availability of NCDI-related health services. The Commission prioritized 14 NCDIs and selected 34 accompanying interventions for recommendation to achieve UHC. These interventions were estimated to cost $11.76 USD per capita annually, which represents 15% of current total health expenditure. This investment could potentially avert 9,322 premature deaths per year by 2030. Conclusions and Recommendations: An expanded set of priority NCDI conditions and health sector interventions are required in Kenya to achieve UHC, particularly for disadvantaged socioeconomic groups. We provided recommendations for integration of services within existing health services platforms and financing mechanisms and coordination of whole-of-government approaches for the prevention and treatment of NCDIs
Recombinant nanobodies as cheap and customizable reagents for unicellular algae detection
At the present, the identification of planktonic species in coastal water mainly relies on light microscopy
observations. This kind of analyses is performed by highly trained personnel, requires lab equipment and long
processing time. High-throughput and easy-to-perform methods are instead highly needed for routine costal and
ballast water monitoring.
Immuno-reagents are widely employed in the medical field for routine diagnostics, where they provide the necessary
sensitivity and specificity, as for example for cancer subtype characterization. Reagents of similar grade are so far not
widely available for both diagnostics and basic research of microalgae. We describe the first successful isolation of a
single-domain antibody (nanobody or VHH) from a pre-immune library, its engineering into application-ready
reagents, and its inexpensive production as recombinant fusion protein.
Alexandrium minutum was chosen as a model organism to test the feasibility of the procedure. The procedure foresees
the panning of a pre-immune phage library of VHHs that was used for in vitro selection against directly the target cells.
Monoclonal nanobodies specific for A. minutum cells were identified and optimized for recombinant production as
fusion with fluorescent proteins in bacterial hosts. Such fluorescently-tagged VHHs were validated by
immunofluorescence and cytofluorimetry for their selectivity by testing unicellular algal species that can be found in
the same environment of A. minutum. Two nanobodies were found to be highly specific for the target cells, were able
to bind also cysts of A. minutum and they gave no cross-reaction, even for a not-toxic strain of the closely related A.
tamutum.
Different tags can be then fused to the selected nanobodies and used instead of the fluorescent proteins to obtain a
reagent immediately applicable to further techniques, such as cell Enzyme Linked Immuno Sorbent Assay (ELISA) or
biosensor surface functionalization. The newly produced reagents can be applied for direct whole-cell detection in
seawater, bypassing the need of cell processing required for DNA or RNA diagnostics, and can be used for both alive
and fixed cells, guaranteeing the possibility to check old samples and to perform confirmatory morphological studies