31 research outputs found
Differential Taxol-dependent arrest of transformed and nontransformed cells in the G1 phase of the cell cycle, and specific-related mortality of transformed cells.
Organic matter recycling in a beach environment influenced by sunscreen products and increased inorganic nutrient supply (Sturla, Ligurian Sea, NW Mediterranean)
The beaches are sites where the human influence may be strong and the beach ecosystems have often shown a
high sensibility to environmental alterations. These zones may be affected by a large series of anthropogenicderived
pressures, such as unbalanced inorganic nutrient input, that may cause anomalous development of
primary production, altering the structure of the trophic webs. Furthermore, the utilisation of cosmetic
sunscreen products is reaching unexpected levels, thus assuming a potentially important as well as unknown
role in the contamination of marine environments. The present study was planned to test the response of the
beach ecosystem to increases in inorganic nutrients (nitrate and phosphate) and to the input of a widely used
cosmetic sunscreenproduct. A short-term laboratory experiment was carried out on microsystems consisting
of sediments and seawater from the swash zone of a Ligurian city beach (Sturla). The processes related to
organic matter (OM) recycling and some microbial food web components (bacteria and micro-autotrophic
organisms) were analysed. The multivariate statistical analysis of the results showed that the increase in
inorganic nutrients and sunscreen caused only a transient alteration in the OM recycling processes in the
seawater. The sedimentary processes, instead, were different in the different systems, although starting from
the same condition. In the sediment, surprisingly, an increase in inorganic nutrients did not lead to an increase
in the primary biomass nor to significantly higher bacterial abundance, while the sunscreen caused increased
OM recycling, especially devoted to protein and lipid mobilisation, supporting a growing bacterial and
autotrophic community by reducing the bottom-up pressure. Additional toxicity tests performed on protozoa
highlighted that, while the inorganic nutrients seemed to show no effects, sunscreen decreased the protozoan
viability, thus likely favouring microautotrophic and bacterial increases by reducing the top-down pressure
Organic matter recycling in a beach environment influenced by sunscreen products and increased inorganic nutrient supply (Sturla, Ligurian Sea, NW Mediterranean).
Effects of organophosphate compounds on a soil protist, Colpoda inflata (Ciliophora, Colpodidae)
Many investigations on protists indicate that they play an important role in agricultural soils. We have tested the effects of three organophosphate
(OP) pesticides, basudin, cidial, and fenix, on the soil ciliate Colpoda inflata, and examined its viability, fission rate, ability
to excyst and extrude macronuclear chromatin into cytoplasm. Exposure to these OPs caused a dose-dependent effect on cell viability,
and significantly reduced the mean fission rate at a concentration of 1/105 v/v. After exposure of resting cysts to 1/105 v/v or 1/106 v/v
concentrations of basudin or cidial, the number of excysted cells was significantly lower than that of the controls. Conversely, exposure to
a 1/105 v/v fenix concentration did not affect excystment and exposure to 1/106 v/v was found to promote excystment. Moreover, exposure
to these OPs (1/104 v/v or 1/105 v/v) interferred with the ability to extrude macronuclear chromatin. The median lethal concentration
in 60 min for each OPs tested was at least a hundred times lower than the doses recommended by the manufacturer. Finally, as the
inhibition of cholinesterase (ChE) activity is the first target of OPs, the presence of ChE activity was checked in C. inflata. Three ChE
activities were found, hydrolyzing the substrates acetyl-b-methyl thiocholine iodide, propionyl thiocholine iodide and butyryl thiocholine
iodide, that appeared to be very low and not inhibited by OP-exposure.
2006 Elsevier Ltd. All rights reserved
Nitric oxide production is inhibited by xenobiotic compounds in the protozoan Paramecium primaurelia.
The notable increase in agricultural and industrial activities over the last decades has caused a
considerable increase in anthropogenic waste and, consequently, the presence of pollutants in both
water and sediments. For this reason, there is great interest in identifying alternative models and
bioassays complying with the 3Rs strategy (aimed at Reducing, Refining and Replacing tests on
vertebrate organisms in toxicological studies). Protozoa seem to be well suited to this strategy and it is
widely accepted that assays with protozoa are relevant to the study of environmental modifications due
to the presence of xenobiotic compounds.
Recently, we detected the presence of nitric oxide synthase (NOS)-related NADPH-diaphorase activity
and neuronal NOS-relatedmolecules, immunologically recognized by the anti-rat brain NOS antibody, in
a single-cell freshwater eukaryote, Paramecium primaurelia. In this work we have looked for the basal NO
production in living cells of P. primaurelia using the specific fluorescent probe 4,5-diaminofluorescein
diacetate (DAF-2 DA) and measuring the intracellular NO levels with image analysis. The NO production
was sensitive to compounds modulating NOS activity such as: S-methyl-tiocitrulline, an NOS activity
inhibitor, L-NAME, an analogue of arginine that inhibits NO production, arginine, an NOS substrate, or
sodium nitroprusside, an NO donor. The NO production in P. primaurelia was also shown to be sensitive
to mM concentrations of heavy metals (HgCl2 and CdCl2), or mM concentrations of pesticides (diazinon
and AFD 25), thus representing a potential biomarker for environmental biomonitoring. The possible
involvement of cellular Ca2+ concentration, assayed by the fluorescent probe chlortetracycline
hydrochloride, in NO production was examined after xenobiotic exposure
Evidence for the presence of a mammalian-like cholinesterase in Paramecium primaurelia (Protista, Ciliophora) developmental cycle
By histochemical and immunohistochemical methods, the presence of cholinergic-like molecules has previously been demonstrated in Paramecium primaurelia, and their functional role in mating-cell pairing was suggested. In this work, both true acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities were electrophoretically investigated, and the presence of molecules immunologically related to BuChE was checked by immunoblotting. The AChE activity, shown in the membrane protein fraction of mating-competent cells and in the cytoplasmic fraction of immature cells, is due to a 260-kDa molecular form, similar to the membrane-bound tetrameric form present in human erythrocytes. This AChE activity does not appear in either the cytoplasmic fraction of mating-competent cells or in the membrane protein fraction of immature cells. No evidence was found for the presence or the activity of BuChE-like molecules. The role of AChE in P. primaurelia developmental cycle is discussed