UPLC/ESI/MS profiling of red algae Galaxaura rugosa extracts and its activity against malaria mosquito vector, Anopheles pharoensis, with reference to Danio rerio and Daphnia magna as bioindicators.

BACKGROUND: Anopheles pharoensis has a major role in transmitting several human diseases, especially malaria, in Egypt?. Controlling Anopheles is considered as an effective strategy to eliminate the spread of malaria worldwide. Galaxaura rugosa is a species of red algae found in tropical to subtropical marine environments. The presence of G. rugosa is indicative of the ecosystem's overall health. The current work aims to investigate UPLC/ESI/MS profile of G. rugosa methanol and petroleum ether extracts and its activity against An. pharoensis and non-target organisms, Danio rerio and Daphnia magna. METHODS: Galaxaura rugosa specimens have been identified using DNA barcoding for the COI gene and verified as G. rugosa. The UPLC/ESI/MS profiling of G. rugosa collected from Egypt was described. The larvicidal and repellent activities of G. rugosa methanol and petroleum ether extracts against An. pharoensis were evaluated, as well as the toxicity of tested extracts on non-target organisms, Dan. rerio and Dap. magna. RESULTS: The UPLC/ESI/MS analysis of methanol and petroleum ether extracts led to the tentative identification of 57 compounds belonging to different phytochemical classes, including flavonoids, tannins, phenolic acids, phenyl propanoids. Larval mortality was recorded at 93.33% and 90.67% at 80 and 35 ppm of methanol and petroleum ether extracts, respectively, while pupal mortality recorded 44.44 and 22.48% at 35 and 30 ppm, respectively. Larval duration was recorded at 5.31 and 5.64 days by methanol and petroleum ether extracts at 80 and 35 ppm, respectively. A decrease in acetylcholinesterase (AChE) level and a promotion in Glutathione-S-transferase (GST) level of An. pharoensis 3rd instar larvae were recorded by tested extracts. The petroleum ether extract was more effective against An. pharoensis starved females than methanol extract. Also, tested extracts recorded LC50 of 1988.8, 1365.1, and 11.65, 14.36 µg/mL against Dan. rerio, and Dap. magna, respectively. CONCLUSIONS: Using red algae derivatives in An. pharoensis control could reduce costs and environmental impact and be harmless to humans and other non-target organisms.

The impact of amine and carboxyl functionalised microplastics on the physiology of daphnids.

Plastic waste is considered a major threat for terrestrial, marine and freshwater ecosystems. Ingestion of primary or secondary microparticles resulting from plastic degradation can lead to their trophic transfer raising serious health concerns. In this study, the effect of amine and carboxy functionalized polystyrene microparticles on the physiology of daphnids was investigated with a combination of phenotypic and metabolic endpoints. Carboxy functionalized microparticles showed higher toxicity in acute exposures compared to their amine counterparts. Accumulation of both microparticles in animal gut was confirmed by stereo-microscopy as well as fluorescent microscopy which showed no presence of particles in the rest of the animal. Fluorescence based quantification of microparticles extracted from animal lysates validated their concentration-dependent uptake. Additionally, exposure of daphnids to amine and carboxy functionalized microparticles resulted in increased activities of key enzymes related to metabolism and detoxification. Finally, significant metabolic perturbations were discovered following exposure to microplastics. These findings suggest that polystyrene microparticles can hinder organism performance of the freshwater species and highlight the importance of seeking for holistic and physiological endpoints for pollution assessment.

Ecotoxicity of pesticide formulations and their mixtures: the case of potato crops in Costa Rica.

Despite their environmental implications, ecotoxicological information regarding pesticide mixtures is relatively scarce. This study aimed to determine the ecotoxicity of individual pesticide formulations and their mixtures (insecticides and fungicides), which are applied during the production cycle of potato, according to agricultural practices from a Latin American region in Costa Rica. Two benchmark organisms were employed: Daphnia magna and Lactuca sativa. First, the evaluation of individual formulations (chlorothalonil, propineb, deltamethrin+imidacloprid, ziram, thiocyclam and chlorpyrifos) revealed differences between available EC50 for active ingredients (a.i.) and their respective formulations toward D. magna; on the contrary, no information could be retrieved from scientific literature for comparison in the case of L. sativa. In general, acute toxicity was higher toward D. magna than L. sativa. Moreover, interactions could not be determined on L. sativa, as the chlorothalonil formulation was not toxic at high levels and the concentration-response to propineb could not be fitted to obtain an IC50 value. The commercial formulation composed of deltamethrin+imidacloprid followed the concentration addition model (when compared with parameters retrieved from individual a.i.) and the other three mixtures evaluated (I: chlorothalonil-propineb-deltamethrin+imidacloprid; II: chlorothalonil-propineb-ziram-thiocyclam; III: chlorothalonil-propineb-chlorpyrifos) produced an antagonistic effect on D. magna, thus suggesting less acute toxicity than their individual components. Subsequent chronic studies showed that one of the most toxic mixtures (II) negatively affected D. magna reproduction at sublethal concentrations indicating that this mixture poses a risk to this species if these pesticides co-exist in freshwater systems. These findings provide useful data to better estimate the impact of real agricultural practices related to the use of agrochemicals.

Synchrotron-Based X-ray Fluorescence Imaging Elucidates Uranium Toxicokinetics in Daphnia magna.

A combination of synchrotron-based elemental analysis and acute toxicity tests was used to investigate the biodistribution and adverse effects in Daphnia magna exposed to uranium nanoparticle (UNP, 3-5 nm) suspensions or to uranium reference (Uref) solutions. Speciation analysis revealed similar size distributions between exposures, and toxicity tests showed comparable acute effects (UNP LC50: 402 µg L-1 [336-484], Uref LC50: 268 µg L-1 [229-315]). However, the uranium body burden was 3- to 5-fold greater in UNP-exposed daphnids, and analysis of survival as a function of body burden revealed a ∼5-fold higher specific toxicity from the Uref exposure. High-resolution X-ray fluorescence elemental maps of intact, whole daphnids from sublethal, acute exposures of both treatments revealed high uranium accumulation onto the gills (epipodites) as well as within the hepatic ceca and the intestinal lumen. Uranium uptake into the hemolymph circulatory system was inferred from signals observed in organs such as the heart and the maxillary gland. The substantial uptake in the maxillary gland and the associated nephridium suggests that these organs play a role in uranium removal from the hemolymph and subsequent excretion. Uranium was also observed associated with the embryos and the remnants of the chorion, suggesting uptake in the offspring. The identification of target organs and tissues is of major importance to the understanding of uranium and UNP toxicity and exposure characterization that should ultimately contribute to reducing uncertainties in related environmental impact and risk assessments.

Daphnia magna as biological harvesters for green microalgae grown on recirculated aquaculture system effluents.

The sustainability of recycling aquaculture systems (RAS) is challenged by nutrient discharges, which cause water eutrophication. Efficient treatments for RAS effluents are needed to mitigate its environmental impacts. Microalgae assimilate nutrients and dissolved carbon into microbial biomass with value as feed or food ingredient. However, they are difficult to harvest efficiently. Daphnia magna is an efficient filter feeder that grazes on microalgae at high rates and serves as valuable fish feed. Combining nutrient removal by microalgae and biomass harvesting by D. magna could be a cost-effective solution for wastewater valorization. Nutrient removal from unsterilized aquaculture wastewater was evaluated using the microalgae species Chlorella vulgaris, Scenedesmus dimorphus, and Haematococcus pluvialis. The first two algae were subsequently harvested using D. magna as a grazer, while H. pluvialis failed to grow stably. All phosphorus was removed, while only 50-70 % nitrogen was recovered, indicating phosphorus limitation. Shortening the hydraulic retention time (HRT) or phosphorus dosing resulted in increased nitrogen removal. C. vulgaris cultivation was unstable at 3 days HRT or when supplied with extra phosphorus at 5 days HRT. D. magna grew on produced algae accumulating protein at 20-30 % of dry weight, with an amino acid profile favorable for use as high value fish feed. Thus, this study demonstrates the application of a two steps multitrophic process to assimilate residual nutrients into live feeds suitable for fish.

Two-phase effects of environmentally relevant lanthanum on life-history traits of Daphnia magna and transgenerational bioenergetic profiles: Implications for nutritional and environmental consequences.

The versatile applicability of rare earth elements (REEs) especially lanthanum (La) in diverse fields, has led to large-scale mineral exploitation globally, inevitably resulting in substantial release of La into environment. As emerging anthropogenic environmental contaminant, La-induced toxicological effects and potential ecotoxicological implications in relation to realistic levels of La in aquatic ecosystems are becoming major concerns. To address these issues, Daphnia magna was selected as a prototype, and toxicity tests were conducted to explore the effects of La exposure on life-history characteristics and fecundity fitness, as showcased by quantitative variations from the individual level to population scale. In parallel, to further denote transgenerational caloric impacts of parental La exposure, bioenergetic profiles on newborn neonates were concurrently determined by measuring macromolecule forms in terms of proteins, glycogens and lipids to quantify nutritional alterations at progeny level. The results revealed that low-dose La exposure slightly stimulated the demographic potential and nutritional responses, exhibiting dose-dependent hormesis-like effects and promising non-toxicological potential to Daphnia, whereas high-dose La exposure of greater than 59.2 µg La L - 1, conspicuously imposed detrimental effects on quantity and quality of offspring, i.e. not only reducing body size, lifespan expectancy and reproductive output in a concentration-dependent way and resulting in lower population fitness by a dynamic life-table analysis, but eventually leading to the decrease of nutritional qualities and caloric contents on neonates. Taken together, these two-phase findings regarding the dose-related shift from hormesis to inhibition not only provided valuable insights into the complicated biological outcomes of La effects on environmentally-relevant organisms, but experimentally highlighted the significant implications of considering environmental and nutritional consequences in ecologically assessing the La-triggered risk at environmentally realistic occurrences, particularly on gradient scenarios crossing upstream and downstream of highly complex mining watersheds.

Synchrotron XRF and Histological Analyses Identify Damage to Digestive Tract of Uranium NP-Exposed Daphnia magna.

Micro- and nanoscopic X-ray techniques were used to investigate the relationship between uranium (U) tissue distributions and adverse effects to the digestive tract of aquatic model organism Daphnia magna following uranium nanoparticle (UNP) exposure. X-ray absorption computed tomography measurements of intact daphnids exposed to sublethal concentrations of UNPs or a U reference solution (URef) showed adverse morphological changes to the midgut and the hepatic ceca. Histological analyses of exposed organisms revealed a high proportion of abnormal and irregularly shaped intestinal epithelial cells. Disruption of the hepatic ceca and midgut epithelial tissues implied digestive functions and intestinal barriers were compromised. Synchrotron-based micro X-ray fluorescence (XRF) elemental mapping identified U co-localized with morphological changes, with substantial accumulation of U in the lumen as well as in the epithelial tissues. Utilizing high-resolution nano-XRF, 400-1000 nm sized U particulates could be identified throughout the midgut and within hepatic ceca cells, coinciding with tissue damages. The results highlight disruption of intestinal function as an important mode of action of acute U toxicity in D. magna and that midgut epithelial cells as well as the hepatic ceca are key target organs.

Does a Diet Rich in the Bacterium Rhodopirellula rubra Improve Daphnia magna Performance?

BACKGROUND: In the wild various organisms contribute to daphnids diet. This study, intendeds to evaluate the potential of the concentration of Rhodopirellula rubra as a single or supplementary food source for Daphnia magna. METHODS: Feeding assays were performed according to standard guidelines for chronic assays (21 days), and life-history parameters and several biomarkers (protein content, oxidative stress, energetic reserves and pigments) were measured. Five food regimens were conducted with 20 individual replicates (A - R. subcapitata; 0.2 - suspension of R. rubra at 0.2 arbitrary units (AU); 0.4 - suspension of R. rubra at 0.4 AU; 0.2+A - suspension of R. rubra at 0.2+alga; 0.2+A-suspension of R. rubra at 0.4 AU + alga). Additionally, the effects of three diets (A, 0.2, and 0.2+A) on the longevity of D. magna were assessed. RESULTS: The five diets showed a different C, N, and carotenoids composition, with an increase in the mixed diets. The results confirmed that the mixed diets improved D. magna life-history parameters. A decrease in glycogen, and the increase of haemoglobin, protein, and gluthione-S-transferase (GST) were observed. Furthermore, D. magna fed with bacterial single diets, presented worsen life history parameters and a decrease in the protein content. An induction of oxidative stress response (increased catalase and GST), and a significant decrease in lipid peroxidation and an accumulation of glycogen and carotenoids were observed. Overall, an increase in the amount of R. rubra provided to D. magna, from 0.2 AU to 0.4 AU, negatively impacted daphnid performance. No significant effects on Daphnia longevity (a 110-day assay) were observed among the three diets tested. However, a significant survival percentage and fertility (cumulative offspring is more than twice) was observed when D. magna was fed with the mixed diet. CONCLUSIONS: Results demonstrated that different diets provided a nutritional diversified food to the daphnids that induced differences in D. magna performance. The mixed diets proved to be beneficial (with increase in offspring) on D. magna performance, independently of the bacterial concentration tested. When in single diet, bacterial concentration is not nutritionally sufficient to raise D. magna even when in increased concentration.

Nature-based coagulants for drinking water treatment: An ecotoxicological overview.

The intensive human activities extensively contaminated water sources making its treatment a problem of paramount importance, especially with the increasing of global population and water scarcity. The application of natural coagulants has become a promising and environmentally friendly alternative to conventional ones. This study was aimed at evaluating the efficiency of four plant extracts namely Agave americana, Carpobrotus acinaciformis, Austrocylindropuntia subulate, and Senicio anteuphorbium as natural coagulants to remove Microcystis aeruginosa cyanobacterium from water. The effects of pH (4, 5, 6, 7, 8 9, and 10) and coagulant dose (5, 10, 15, 20, 25, and 30 mg/L) on the coagulation efficiency were investigated. Results showed that plant-based extracts exhibited high coagulant abilities significantly contributing to the removal of M. aeruginosa cells up to 80% on a case-by-case basis. The ecotoxicity (Daphnia magna, Aliivibrio fischeri, Raphidocelis subcapitata, and Sorghum saccharatum) was absent or presented very slight acute toxicity up to 12.5 mg/L being S. anteuphorbium the least toxic. PRACTITIONER POINTS: Nature-based plant extracts showed removal rates up to 80%. Lower pH and A. subulate and S. anteuphorbium were the most efficient coagulants Toxicity effects were plant extracts-based and dose function. A. subulate and S. anteuphorbium were the least toxic extracts.

Proteome changes in an aquatic invertebrate consumer in response to different nutritional stressors.

Nutrient imbalances in zooplankton are caused by the differences in elemental content of producers and the demand for elements in consumers, which alter the life-history traits in consumers. Changes in life-history traits are mediated through metabolic pathways that affect gene expression and the metabolome. However, less is known about proteomic changes to elemental-limitation in zooplankton. Here, we grew Daphnia pulex under high food quantity and quality (HF), low food quantity (LF), and phosphorus (P)-limited (PL) diets for six days and measured growth, elemental composition, and the proteome. Daphnids in both LF and PL diets grew less. Animals in LF diets had less carbon (C), while daphnids in PL diets had less P compared to HF fed animals. In total, we identified 1719 proteins that were used in a partial least squares regression discriminant analysis (PLS-DA). Focusing on a subset of the proteome, the PLS-DA resulted in a clear separation between animals fed HF diets and PL and LF diets. Many proteome changes in nutrient-limited diets are associated with growth, reproduction, lipid metabolism, and nutrient assimilation. Regardless of the limiting nutrient, there were less hemoglobin and small subunit processome component proteins compared to HF fed animals. Daphnids fed LF diets had less vitellogenin fused superoxide dismutase and more lipid-droplet hydrolase, whereas Daphnia fed PL diets had higher abundances of cytochrome P450 and serine protease. Our proteome results compliment other "omic" studies that could be used to study Daphnia physiology in lakes.

Treatment of electropolishing industrial wastewater and its impact on the immobilisation of Daphnia magna.

The amount of industrial pollution entering the environment and its impact on living organisms is an ongoing concern. At the same time, due to an increasing awareness, new methods of wastewater treatment are being explored that are not only effective but also environmentally acceptable. Meeting environmental standards for permitted concentrations is a necessity, but investigating the effects of wastewater on living organisms is also an important issue. In this paper, the influence of metal ions (Fe(III), Cr(III), Ni(II), Cu(II)) in industrial wastewater from electropolishing of stainless steel on Daphnia magna has been investigated. Daphnids have been exposed to wastewater both before and after treatment (Ca(OH)2 precipitation, sorption with peat). Immobilisation in a 48-h acute toxicity test and EC50 has been determined. In the case of studied industrial wastewater, the organic content (expressed as total organic carbon) of the effluent has a positive impact in terms of the survival of D. magna and increases the range of heavy metal concentrations tolerated by them. The application of a two-stage process with Ca(OH)2 neutralisation followed by sorption with peat allows for the removal of almost 100% of metal ions from the wastewater. The reduction obtained ensured a limited impact on D. magna and a decrease in immobilisation to less than 10%. Proper execution of the wastewater treatment process ensures a reduction of its negative impact on living organisms.

The capture of crude oil droplets by filter feeders at high and low Reynolds numbers.

Crustacean filter feeders capture oil droplets with the use of their ramified appendages. These appendages behave as paddles or sieves, based on the system's Reynolds number. Here, we used high-speed videography, scanning electron microscopy and fluid mechanics to study the capturing mechanisms of crude oil droplets and the filtering appendage's wettability by two species of barnacles (Balanus glandula and Balanus crenatus) and of the freshwater cladoceran Daphnia magna. Our results show that barnacle appendages behave as paddles and capture droplets in their boundary layers at low Reynolds number. At high Reynolds number, droplets are most likely to be captured via direct interception. There is an intermediate range of Reynolds number where droplets can be captured by both mechanisms at the same time. Daphnia magna captures droplets in the boundary layers of the third and fourth pair of thoracic legs with a metachronal motion of the appendages. All studied surfaces were revealed to be highly lipophobic, demonstrating captured oil droplets with high contact angles. We also discuss implications of such capture mechanisms and wettability on potential ingestion of crude oil by filter feeders. These results further our understanding of the capture of crude oil by filter feeders, shedding light on the main entry point of oil in marine food webs.

Chemical characterization and bioactive potential of Thymus×citriodorus (Pers.) Schreb. preparations for anti-acne applications: Antimicrobial, anti-biofilm, anti-inflammatory and safety profiles.

ETHNOPHARMACOLOGICAL RELEVANCE: Thymus × citriodorus (Pers.) Schreb. is an interspecific hybrid between Thymus pulegioides and Thymus vulgaris, known for its pharmacological activities as diaphoretic, deodorant, antiseptic and disinfectant, the last mostly related with its antimicrobial activity. The folk use of other extracts, as hydrolates, have also been disseminated, as regulators of oily skin with anti-acne effect. AIM OF THE STUDY: We aimed to evaluate the anti-acne potential of two Thymus x citriodorus (TC) preparations, the essential oil (EO) and the hydrolate, to be used as active ingredients for skin applications. Specifically, we intend to validate their anti-acne potential by describing their activity on acne related bacteria, bacterial virulence, anti-oxidant and anti-inflammatory potential, and biocompatibility on inflammatory cells. Additionally, we aimed to report their ecotoxicity under the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), thus focusing not only on the consumer, but also on environmental safety assessment. MATERIALS AND METHODS: Minimum inhibitory concentration (MIC) against C. acnes, S. aureus and S. epidermidis was evaluated. Minimum lethal concentration (MLC) was also determined. The effect on C. acnes biofilm formation and disruption was evaluated with crystal violet staining. Anti-inflammatory activity was investigated on LPS-stimulated mouse macrophages (RAW 264.7), by studying nitric oxide (NO) production (Griess reagent) and cellular biocompatibility through MTT assay. In-vitro NO and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging potential were also evaluated. The ecotoxicity was evaluated using Daphnia magna acute toxicity assays. RESULTS: EO presented direct antimicrobial activity, with visual MICs ranging from 0.06% for S. epidermidis and C. acnes to 0.125% for S. aureus. MLCs were higher than the obtained MICs. Hydrolate revealed visual MIC only for C. acnes. TC essential oil was effective in preventing biofilm formation and disrupting preformed biofilms even at sub-inhibitory concentrations. Hydrolate showed a more modest anti-biofilm effect. Regarding anti-inflammatory activity, TC hydrolate has a higher cellular biocompatibility. Still, both plant preparations were able to inhibit at least 50% of NO production at non-cytotoxic concentrations. Both EO and hydrolate have poor anti-oxidant activities. Regarding the ecotoxicity, TC essential oil was classified under acute 3 category, while the hydrolate has proved to be nontoxic, in accordance to the GHS. CONCLUSIONS: These results support the anti-acne value of different TC preparations for different applications. TC hydrolate by presenting higher biocompatibility, anti-inflammatory potential and the ability to modulate C. acnes virulence, can be advantageous in a product for everyday application. On the other hand, EO by presenting a marked antimicrobial, anti-biofilm and anti-inflammatory activities, still with some cytotoxicity, may be better suited for application in acute flare-ups, for short treatment periods.

Phenolic Characterization and Neuroprotective Properties of Grape Pomace Extracts.

Vitis vinifera (grape) contains various compounds with acknowledged phytochemical and pharmacological properties. Among the different parts of the plant, pomace is of particular interest as a winemaking industry by-product. A characterization of the water extract from grape pomace from Montepulciano d'Abruzzo variety (Villamagna doc) was conducted, and the bioactive phenolic compounds were quantified through HPLC-DAD-MS analysis. HypoE22, a hypothalamic cell line, was challenged with an oxidative stimulus and exposed to different concentrations (1 µg/mL-1 mg/mL) of the pomace extract for 24, 48, and 72 h. In the same conditions, cells were exposed to the sole catechin, in a concentration range (5-500 ng/mL) consistent with the catechin level in the extract. Cell proliferation was investigated by MTT assay, dopamine release through HPLC-EC method, PGE2 amount by an ELISA kit, and expressions of neurotrophin brain-derived neurotrophic factor (BDNF) and of cyclooxygenase-2 (COX-2) by RT-PCR. The extract reverted the cytotoxicity exerted by the oxidative stimulus at all the experimental times in a dose-dependent manner, whereas the catechin was able to revert the oxidative stress-induced depletion of dopamine 48 h and 72 h after the stimulus. The extract and the catechin were also effective in preventing the downregulation of BDNF and the concomitant upregulation of COX-2 gene expression. In accordance, PGE2 release was augmented by the oxidative stress conditions and reverted by the administration of the water extract from grace pomace and catechin, which were equally effective. These results suggest that the neuroprotection induced by the extract could be ascribed, albeit partially, to its catechin content.

Synthesis, In Silico and In Vitro Evaluation of Antimicrobial and Toxicity Features of New 4-[(4-Chlorophenyl)sulfonyl]benzoic Acid Derivatives.

The multi-step synthesis, physico-chemical characterization, and biological activity of novel valine-derived compounds, i.e., N-acyl-α-amino acids, 1,3-oxazol-5(4H)-ones, N-acyl-α-amino ketones, and 1,3-oxazoles derivatives, bearing a 4-[(4-chlorophenyl)sulfonyl]phenyl moiety are reported here. The structures of the newly synthesized compounds were confirmed by spectral (UV-Vis, FT-IR, MS, 1H- and 13C-NMR) data and elemental analysis results, and their purity was determined by RP-HPLC. The new compounds were assessed for their antimicrobial activity and toxicity to aquatic crustacean Daphnia magna. Also, in silico studies regarding their potential mechanism of action and toxicity were performed. The antimicrobial evaluation revealed that the 2-{4-[(4-chlorophenyl)sulfonyl]benzamido}-3-methylbutanoic acid and the corresponding 1,3-oxazol-5(4H)-one exhibited antimicrobial activity against Gram-positive bacterial strains and the new 1,3-oxazole containing a phenyl group at 5-position against the C. albicans strain.

Environmental Risk Characterization of an Antiretroviral (ARV) Lamivudine in Ecosystems.

Antiretroviral drugs for the treatment of human immunodeficiency virus (HIV) and other viral infections are among the emerging contaminants considered for ecological risk assessment. These compounds have been reported to be widely distributed in water bodies and other aquatic environments, while data concerning the risk they may pose to unintended non-target species in a different ecosystem (environment) is scanty. In South Africa and other developing countries, lamivudine is one of the common antiretrovirals applied. Despite this, little is known about its environmental impacts as an emerging contaminant. The present study employed a battery of ecotoxicity bioassays to assess the environmental threat lamivudine poses to aquatic fauna and flora. Daphnia magna (filter feeders), the Ames bacterial mutagenicity test, Lactuca sativa (lettuce) germination test, and the Allium cepa root tip assay were conducted, testing lamivudine at two concentrations (10 and 100 µg/L), with environmental relevance. The Daphnia magna toxicity test revealed a statistically significant response (p << 0.05) with a mortality rate of 85% on exposure to 100 µg/L lamivudine in freshwater, which increased to 100% at 48-h exposure. At lower concentrations of 10 µg/L lamivudine, 90% and 55% survival rates were observed at 24 h and 48 h, respectively. No potential mutagenic effects were observed from the Ames test at both concentrations of lamivudine. Allium cepa bioassays revealed a noticeable adverse impact on the root lengths on exposure to 100 µg/L lamivudine. This impact was further investigated through microscopic examination, revealing some chromosomal aberration in the exposed Allium cepa root tips. The Lactuca sativa bioassay showed a slight adverse impact on both the germination rate of the seeds and their respective hypocotyl lengths compared to the control. Overall, this indicates that lamivudine poses an ecological health risk at different trophic levels, to both flora and fauna, at concentrations previously found in the environment.

Effects of water produced by oil segment on aquatic organisms after treatment using advanced oxidative processes.

The water produced (PW) by the petroleum industry is a potential contaminant to aquatic biota, due to its complex mixture that may contain polycyclic aromatic hydrocarbons (PAHs), organic chemical compounds, including benzene, toluene, ethylbenzene and xylene (BTEX), metals and other components that are known to be toxic. The aim of this investigation was to examine the acute toxicity produced by a PW sample in aquatic organisms Vibrio fischeri and Daphnia similis prior to and after 4 treatments using advanced oxidative processes such as photocatalysis, photoelectrocatalysis, ozonation and photoelectrocatalytic ozonation. Data demonstrated that exposure to PW was toxic to both organisms, as evidenced by reduced luminescence in bacterium Vibrio fischeri and induced immobility in Daphnia similis. After treatment of PW with 4 different techniques, the PW remained toxic for both tested organisms. However, photoelectrocatalysis was more efficient in decreasing toxicity attributed to PW sample. Therefore, data demonstrate the importance of treating PW for later disposal in the environment in order to mitigate ecotoxicological impacts. Further photoelectrocatalysis appeared to be a promising tool for treating PW samples prior to disposal and exposure of aquatic ecosystems.

Toxicological effects of leachate extracts from asphalt mixtures nanomodified under Daphnia magna and Landoltia punctata test organisms.

The incorporation of nanomaterials in binders in the paving area has been studied to improve the mechanical behavior of asphalt mixtures. However, asphalt mixture compounds are susceptible to leaching and deposition in the environment. In this context, this research aimed to investigate the toxic effect of two leachate extracts from asphalt mixtures nanomodified with 2% carbon nanotube and 3% organophilic nanoclay, compared to conventional mixture, using Daphnia magna and Landoltia punctata as test organisms. The nanomaterials were characterized to confirm morphology, stability and effective diameter. Extracts were chemically characterized using the Fourier-Transform Infrared Spectroscopy (FTIR) technique, which indicated presence of functional groups of the asphalt binder in greater intensity in the leachate from conventional mixture. Acute toxicity with D. magna indicated EC50,48h of 83.5 ± 6.2 mL/L for leachate extract from conventional mixture, 306.0 ± 87.6 mL/L for leachate extract from mixture with nanoclay and 464.8 ± 32.1 mL/L for leachate extract from mixture with carbon nanotube. No leachate caused significant chronic toxicity. As for L.punctata, concentrations that caused 50% growth inhibition were 127.5 mL/L for the leachate extract from mixture with carbon nanotube, 196.9 mL/L for the leachate extract from mixture with nanoclay and 205 mL/L for the leachate extract from conventional mixture. For these test organisms, there is no evidence of negative impacts directly associated with the use of the present nanomaterials in asphalt mixtures. The incorporation of these nanos may also reduce the acute toxicity of the mixtures.

Uranium accumulation and toxicokinetics in the crustacean Daphnia magna provide perspective to toxicodynamic responses.

The importance of incorporating kinetic approaches in order to gain information on underlying physiological processes explaining species sensitivity to environmental stressors has been highlighted in recent years. Uranium is present in the aquatic environment worldwide due to naturally occurring and anthropogenic sources, posing a potential risk to freshwater taxa in contaminated areas. Although literature shows that organisms vary widely with respect to susceptibility to U, information on toxicokinetics that may explain the variation in toxicodynamic responses is scarce. In the present work, Daphnia magna were exposed to a range of environmentally relevant U concentrations (0 - 200 µg L-1) followed by a 48 h depuration phase to obtain information on toxicokinetic parameters and toxic responses. Results showed time-dependent and concentration-dependent uptake of U in daphnia (ku = 1.2 - 3.8 L g-1 day-1) with bioconcentration factors (BCFs) ranging from 1,641 - 5,204 (L kg-1), a high depuration rate constant (ke = 0.75 day-1), the majority of U tightly bound to the exoskeleton (~ 50 - 60%) and maternal transfer of U (1 - 7%). Effects on growth, survivorship and major ion homeostasis strongly correlated with exposure (external or internal) and toxicokinetic parameters (uptake rates, ku, BCF), indicating that uptake and internalization drives U toxicity responses in D. magna. Interference from U with ion uptake pathways and homeostasis was highlighted by the alteration in whole-body ion concentrations, their ionic ratios (e.g., Ca:Mg and Na:K) and the increased expression in some ion regulating genes. Together, this work adds to the limited data examining U kinetics in freshwater taxa and, in addition, provides perspective on factors influencing stress, toxicity and adaptive response to environmental contaminants such as uranium.