Artemia Larvae Research Articles

Potential Effects of Live and Nutrient-Enhanced Food on Growth Performance and Biochemical Composition of Blue Acara (Andinoacara pulcher)

Fish food and feeding play an important role in understanding the rate of growth, development and reproduction in ornamental fish culture. The current study evaluated the impact of different types of food on the growth of Ornamental fish, Andinoacara pulcher. A comparative analysis of live, prepared, and commercial food was conducted in three feeding groups A, B and C, respectively. For live feed, Artemia larvae were cultured from Artemia seeds, and fed. The growth in terms of weight and body length was measured at 15-day intervals throughout the experimental period of 60 days. In addition, the protein, lipid, ash, and moisture composition of fish were estimated and analyzed. From the results, the fish fed with live artemia feed attained maximum growth when compared to other prepared feed and commercial feed. The specific growth rate (SGR) was found to be maximum in group A (1.46%), followed by group B (1.15%) and group C (0.71%). There is a well-defined relationship between the rate of growth and the type of food consumed. The protein, carbohydrate, and fat content of fish revealed a higher biochemical composition. In conclusion, the growth and biochemical study in the present investigation indicated that the live feed contains good constituents of vital nutrient substances that promote the growth and protein content of ornamental fish, Blue Acara.

Phytofabrication and Characterisation of Zinc Oxide Nanoparticles Using Pure Curcumin.

Zinc oxide and curcumin, on their own and in combination, have the potential as alternatives to conventional anticancer drugs. In this work, zinc oxide nanoparticles (ZnO NPs) were prepared by an eco-friendly method using pure curcumin, and their physicochemical properties were characterised. ATR-FTIR spectra confirmed the role of curcumin in synthesising zinc oxide curcumin nanoparticles (Green-ZnO-NPs). These nanoparticles exhibited a hexagonal wurtzite structure with a size and zeta potential of 27.61 ± 5.18 nm and -16.90 ± 0.26 mV, respectively. Green-ZnO-NPs showed good activity towards studied bacterial strains, including Escherichia coli, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. The minimum inhibitory concentration of Green-ZnO-NPs was consistently larger than that of chemically synthesised ZnO NPs (Std-ZnO-NPs) or mere curcumin, advocating an additive effect between the zinc oxide and curcumin. Green-ZnO-NPs demonstrated an efficient inhibitory effect towards MCF-7 cells with IC50 (20.53 ± 5.12 μg/mL) that was significantly lower compared to that of Std-ZnO-NPs (27.08 ± 0.91 μg/mL) after 48 h of treatment. When Green-ZnO-NPs were tested against Artemia larvae, a minimised cytotoxic effect was observed, with LC50 being almost three times lower compared to that of Std-ZnO-NPs (11.96 ± 1.89 μg/mL and 34.60 ± 9.45 μg/mL, respectively). This demonstrates that Green-ZnO-NPs can be a potent, additively enhanced combination delivery/therapeutic agent with the potential for anticancer therapy.

Decolourization of azo dye using a batch bioreactor by an indigenous bacterium Enterobacter aerogenes ES014 from the waste water dye effluent and toxicity analysis

Effluents of textile industries caused serious environmental problem throughout the world. In this study, a total of 23 bacterial strains from five bacterial species were isolated from the dye effluent. Of these strains, a unique and novel Enterobacter aerogenes ES014 was utilized for dye decolourization and toxicity analysis. The selected strain could effectively decolourize three selected azo dyes. It showed the capability for decolourizing acid orange (82.3 ± 3.6%), methyl orange (78.2 ± 3.3%), and congo red (81.5 ± 3.2%). The selected bacterial strain significantly decolourized 100 mg/L acid orange at 35 °C, pH 7.5 with 6% sodium chloride concentration. Most of the tested nitrogen and carbon sources effectively enhanced decolourization process. It showed the ability to decolourize acid orange in the culture medium containing 1.5% glucose (100 ± 2.8%) and 0.8% beef extract (100 ± 3.1%). A laboratory-scale batch bioreactor was used to decolourize azo dye at optimized culture conditions. The decolourizing ability improved with 100 mL/h hydraulic retention time. The treated wastewater quality was improved due to sharp depletion of Total Dissolved Solids (TDS), pH, Chemical Oxygen Demand (COD), alkalinity and sulphate concentration. The selected bacteria has the potential to produce dye degrading laccase. Laccase was detected during fermentation process in batch bioreactor as a key enzyme for decolourization produced by E. aerogenes ES014. Phytotoxicity and acute toxicity analysis were performed using Arachis hypogaea (pea nut) seed and first instar larvae of Artemia parthenogenetica (brine shrimp). The seed germination rate of treated wastewater was improved (94.3 ± 1.8%) and enhanced survival rate (91.7 ± 2.9%) in the first instar Artemia larvae treated with wastewater after 24 h. Overall, E. aerogenes ES014, might be a promising bacterial strain for the treatment of textile effluents with high azo dye concentrations.

MYCOLOGICAL ANALYSIS OF DRIED FISHES COLLECTED FROM OPEN MARKETS WITH SPECIAL FOCUS ON MYCOTOXIN PRODUCTION

Dried fishes are salted and sun dried fish products consumed by large population owing to their nutrient richness, flavor and long shelf life properties. Contamination of dried fishes by mycotoxin producing fungi pose serious threat to food safety and public health. A total of 27 samples belonging to three varieties of dried fishes collected in Chennai city, India were screened for the isolation of mycotoxin producing fungal contaminants. Mycological examination of samples revealed the prevalence of six types of fungi viz., A. parasiticus (27.27%), A. niger (22.72%), A. fumigatus (18.18%), Penicillium sp. (18.18%), Cladosporium sp. (9.09%) and Euratium sp. (4.54%). Detection using thin layer chromatography indicated that 18.18% of isolates belonging to A. parasiticus, A. fumigatus, Penicillium sp. were positive, while A. niger, Cladosporium sp., and Euratium sp. were negative for mycotoxin production. Further to the bioassay with Artemia larvae, substantial lethality was observed with the mycotoxin of A. parasiticus (100%), followed that of by A. fumigatus and Penicillium sp. (each 50%). The HPLC studies indicated that the mycotoxin produced by A. parasiticus was Aflatoxin G2. Need for proper hygienic practices during processing and handling of dried fishes in order to avoid fungal contamination and likelihood mycotoxicosis in consumers has been suggested.

Comparison of Growth for Cultivated Common carp, Cyprinus carpio Larvae between Earthen Ponds and Recirculation Aquaculture System

A comparison was conducted for growth criteria of common carp, Cyprinus carpio larvae cultivated in earthen ponds and recirculation aquaculture system (RAS) depending on live foods (phytoplankton and zooplankton stimulated by buffalo fertilizers in earthen ponds, while the larvae cultivated in RAS were feed on Artemia larvae reproduced in vitro, in addition to manufactured pellets (38% crude protein) for common carp in both systems. Three 2500 m2 earthen ponds were cultivated for 90 days with larvae of initial weight 0.002 g at different numbers (40800 larvae for pond 1, 55600 larvae for pond 2 and 36400 larvae for pond 3). These larvae depend on natural food for 19 days, then fed on manufactured feed. Fishes were weighed every 19 days to change daily feed. Three replicates of RAS plastic tanks (100 letter capacity) cultivated for 90 days with 0.002 g larvae at a density of 2 larvae per one liter (160 larvae at each plastic tank). These larvae fed for 15 days to saturation (4 meals daily) with Artemia larvae and small Artemia, then fed on manufactured feed. Subsequently, fishes were weighed every 15 days to change daily feed. Larvae cultivated in earthen ponds recorded weight gain of 26.90 g, daily growth of 0.30 gday-1, relative growth of 1345000%, specific growth of 10.56 %day-1, feed conversion of 1.25 and survival rate of 13.16%. Larvae cultivated in RAS system recorded weight gain of 1.53 g, daily growth of 0.02 gday-1, relative growth of 76200%, specific growth of 7.37 %day-1, feed conversion of 2.82 and survival rate of 72.32%. Statistical analysis of results revealed significant differences (p>0.05) in all growth criteria for larvae cultivated in both systems. Final conclusion that earthen pond was better than RAS systems in producing fingerlings of common carp.

Toxic effects of two commercial polybrominated diphenyl ethers on Artemia larvae at three developmental stages

Abstract Toxic effects of two commercial products, penta-BDE (DE-71) and octa-BDE (DE-79), on larvae of the brine shrimp, Artemia, were studied. Results showed that their toxic effects were related not only to the concentration and exposure time, but also to the developmental stage of Artemia. Newly hatched Artemia nauplii showed stronger tolerance than those at metanauplius stage or pseudoadult stage, while DE-71 showed a stronger toxic effect than DE-79 to some extent. Abnormal behaviour of Artemia larvae might occur within 12 h, and sometimes mortality rates increased quickly even if there was no death within 36 h. Both DE-71 and DE-79 showed significant influences on the body length of Artemia larvae within 24 h; the higher the concentration, the stronger the inhibition. As far as a toxic testing standard is concerned, further experimental studies on the selection of Artemia population and developmental stage are essential.

A study on primary diets for juveniles of red claw crayfish Cherax quadricarinatus

To study the effect of primary diets on the growth of red claw crayfish and provide guidance, three experiments were carried out in this study. The results of Experiment-I showed: (a) The juveniles with part of yolk sac just disappeared could feed on Artemia larvae, but those with a whole yolk sac could not. The survival and growth rates of the juveniles fed with Artemia were higher than those not fed. (b) There were two eating modes for juveniles. When fed on small food, the juvenile would clamp the food, when fed on large food, the juvenile would hold the food in its arms, then grasped a small piece of food and nibble it. The results of Experiment-II showed: (a) The survival and growth rates of juveniles fed with Artemia were higher than those fed with the formula feed. (b) The survival rate and body weight were higher when fed twice a day than once a day. The results of Experiment-III showed: The survival, growth rates, activities of trypsin of group #2 and group #5 were higher than those of other groups. In conclusion, we came to a conclusion that (a) The primary diet should be offered and available in the water environment immediately when the yolk sac was disappearing. (b) Formula feed should be designed to be easily clamped and stable in water. (c) It was necessary to feed the juveniles twice a day. (d) The primary diet with 85% formula feed +14% Artemia +1% spirulina powder could be applied in future seedling production.

Evaluation of Enterococcus hirae LAB3 as potential probiont against Vibrio harveyi in Artemia nauplii and Asian seabass larvae (Lates calcarifer) cultures

Aim: To evaluate the ability of to inhibit the growth of V. harveyi in in-vitro co-culture assay and confer protection towards Artemia nauplii and seabass larvae against V. harveyi in in-vivo assay. Methodology: Enterococcus hirae was co-cultured with V. harveyi for 96 hrs and the samples were taken every 6 hr interval to determine the growth of the pathogen in in-vitro assay. In the in-vivo assay, E. hirae at different concentrations were introduced to the Artemia nauplii and seabass larvae cultures. After 24-hr incubation period, V. harveyi 6 -1 at concentration 10 CFU ml were added into the respective experimental tanks. Mortality was observed and recorded daily, until 50% mortality was observed in negative control group which challenged with V. harveyi only. Results: E. hirae was able to reduce the numbers of V. harveyi after 12 hr of co-culture incubation. In addition, E. hirae was administered into the Artemia nauplii and conferred protection 6 against V. harveyi with the best survival rate at concentration of 10 -1 CFUmL (70±3.1%). The untreated group seabass larvae challenged with V. harveyi presented low survival of (16.7±3.3%), 6 -1 while fish treated with probiotic E. hirae at 10 CFUml showed significantly increased survival rates (68.3±0.9%) after challenged. The survival of healthy unchallenged fish treated with probiotic was not significantly different with the control group. The pathogen loaded also reduced in groups treated with E. hirae respectively Interpretation: E. hirae strain LAB3, a potential probiont was able to reduce the number of Vibrios and conferred protection to Artemia and seabass larvae.

Feeding Artemia larvae with yeast heat shock proteins 82 (HSPs82) to enhance the resistance against abiotic stresses (hyperosmotic and high temperatures)

Feeding farmed Artemia with yeast heat shock proteins is a novel way to protect them from stress conditions during the culture. In this study, the effect of feeding with stressed new identified Saccharomyces cerevisiae strain YG3-1 yeasts (containing induced heat shock proteins) on the survival of Artemiain stress conditions, was evaluated. For this purpose, heat shock proteins 82 (Hsps 82) of mentioned yeasts were induced by applying the high thermal (30, 35 and 40 ˚C) and high salinity (60, 120, 180 and 240 g.l-1) stresses. After that, two different species of Artemia (Artemia urmiana and A. franciscana) were fed with treated yeasts during the culture. Then, to investigate the effects of S. cerevisiae strain YG3-1 Hsps82 on Artemia survival, after the end of feeding, adult individuals of both species were exposed to authorized high salinity (230 g L-1 and 280 g L-1) and authorized high temperature (35 ˚C and 37 ˚C) as permitted stress for 48 h (hours). Finally, this administration resulted in the resistance of both species against the high salinity and high temperature (p<0.05). This result was confirmed by analysing total protein of Artemia using SDS-PAGE, and suggests that this administration can be used for enhancing the survival of Artemia in stress conditions.

An improved whole life cycle culture protocol for the hydrozoan genetic model Clytia hemisphaerica.

ABSTRACTThe jellyfish species Clytia hemisphaerica (Cnidaria, Hydrozoa) has emerged as a new experimental model animal in the last decade. Favorable characteristics include a fully transparent body suitable for microscopy, daily gamete production and a relatively short life cycle. Furthermore, whole genome sequence assembly and efficient gene editing techniques using CRISPR/Cas9 have opened new possibilities for genetic studies. The quasi-immortal vegetatively-growing polyp colony stage provides a practical means to maintain mutant strains. In the context of developing Clytia as a genetic model, we report here an improved whole life cycle culture method including an aquarium tank system designed for culture of the tiny jellyfish form. We have compared different feeding regimes using Artemia larvae as food and demonstrate that the stage-dependent feeding control is the key for rapid and reliable medusa and polyp rearing. Metamorphosis of the planula larvae into a polyp colony can be induced efficiently using a new synthetic peptide. The optimized procedures detailed here make it practical to generate genetically modified Clytia strains and to maintain their whole life cycle in the laboratory.This article has an associated First Person interview with the two first authors of the paper.

Efek sitotoksik ekstrak buah kapulaga jawa (Amomum compactum Soland. Ex. Maton)

Background: In developed countries cancer is the second leading cause of death after cardiovascular disease. Cancer prevention can be done with synthetic or traditional medicine. However, synthetic treatments often cause side effects and of course require high costs. Java Cardamom (Amomum compactum Soland. Ex Maton) is a plant that contains antioxidants. Antioxidants can inhibit oxidation reactions by binding to free radicals and molecules that are very reactive so that cell damage can be prevented. Cardamom contains flavonoids which can induce cell death programs as well as tannins as free radical scavengers.Objectives: This study aims to determine the LC50 value of Java cardamom (Amomum compactum Soland. Ex Maton) on Artemia salina Leach.Methods: This study was an experimental study using a completely randomized design (CRD) using 180 artemia larvae which were divided into 6 treatment groups. Each group included 10 artemia larvae with varying concentrations of 500 ppm, 250 ppm, 100 ppm, 50 ppm, 10 ppm and 0 ppm (not given extract). Three repetitions were performed for each concentration.Results: The results showed from the observations obtained the LC50 value of Java cardamom extract is 26.60 ppm. So that the Java cardamom extract (Amomum compactum Soland. Ex Maton) has the potential as an anticancer (cytotoxic).Conclusion: Java cardamom extract (Amomum compactum Soland. Ex Maton) is active and can be developed as an anticancer compound.

Toxicity Assay of Fermented Artocarpus altilis Leaves Using Brine Shrimp Lethality Test

Fermented Artocarpus altilis leaves contains phenolic compound that has pharmacological activity. Differences in fermentation method, i.e., aerobic and anaerobic fermentation might change its characteristics and biological activity. The purpose of this study was to compare toxicity properties between aerobically and anaerobically fermented Artocarpus altilis leaves using brine shrimp lethality (BSL) test. Both types of fermented leaves were cold extracted using ethanol solvent (1:6) for 3 x 24 hours. Phytochemical screening was then performed to examine the presence of secondary metabolite compounds. BSL test was performed in 7 treatment groups, i.e., negative control, 1000, 500, 100, 50, 25, 12.5 ppm of extract. Each vial contained 10 Artemia larvae, extract, and sea water up to 10 ml. Toxicity is measured by calculating LC50 after 24 hours observation. The experiment was repeated three times. The results of the study showed that LC50 of aerobic extract was 712 ppm, thus it can be categorized as toxic, while that of anaerobic extract is 1.927 ppm, or non-toxic to the Artemia salina larvae. In conclusion, aerobically fermented Artocarpus altilis leaves had toxicity potency, while anaerobically fermented Artocarpus altilis leaves had no toxicity potency against Artemia salina in BSL test. Key words: Artocarpus altilis, brine shrimp lethality test, toxicity.

Analytical methodology for evaluation of the effects of different leachate treatment methods

Characterisation of the efficiency of leachate treatment methods when considering differentgroups of pollutants as phenolic compounds, PCB,s, PBDEs and phthalates is discussed.Strategies for measurements, identification and quantifications of the organic pollutants arepresented and the use of supported liquid membrane extraction (SLM) and micro porousmembrane extraction (MMLLE) in particular, where small and medium molecules areseparated from large molecules. Acute and chronic toxicity tests by biological methods andthe choice of organisms are also presented as well as the LAQUA-protocol used at the pilotplant in Kristianstad, Sweden. In acute toxicity tests of the leachate a clear accommodating onthe immobility of the Artemia larvae and increasing concentration of leachate was noted.Different species react different on different compounds and therefore on complex effluentsas landfill leachates the use of a battery of bioassays is recommended.

Growth of Amazon ornamental fish Nannostomus beckfordi larvae (Steindachner, 1876) submitted to different stocking densities and feeding management in captivity conditions

The study evaluated productive performance of larvae Nannostomus beckfordi submitted to feeding management (Experiment one) and different stock density (Experiment two) in captivity conditions. The first experiment evaluated feeding rate (100 and 200 nauplii of artemia larvae⁻¹ day⁻¹) and feeding frequency (2 and 4× per day). Second experiment evaluated different stock density (1, 5, 10, 20, 40 larvae per litre). At the end of 15 days, for both experiment, the survival and productive performance such as total length (TL), final weight (FW), specific development rate (SDR), specific growth rate (SGR), uniformity for weight (UW) uniformity for length (UL) and relative condition factor (Kr) was determined. For the main results, there is no significant difference to the rate and feeding frequency. The stock density has no significant difference for UW, Kr and survival. Nonetheless, a reduction in the TL, FW, SDR, SGR and FW with the increase in density (20 for 40 larvae per litre) was observed. Thus, for this species Nannostomus beckfordi during to initial stage using exogenous feeding, it is recommended 20 larvae per litre fed with 100 nauplii per larvae having two meals per day.

A non-toxic microbial surfactant from Marinobacter hydrocarbonoclasticus SdK644 for crude oil solubilization enhancement

This study aims to investigate the ability of a biosurfactant produced by Marinobacter hydrocarbonoclasticus strain SdK644 isolated from hydrocarbon contaminated sediment to enhance the solubilization rate of crude oil contaminated seawater. Phylogenetic analysis shows that strain SdK644 was very closely related to M. hydrocarbonoclasticus with 16S rRNA gene sequence similarity of 97.44%. Using waste frying oil as inducer carbon source, the producing biosurfactant by strain SdK644 was applied to improve crude oil solubilization in seawater. The preliminary characterization of the produced biosurfactant by FT-IR analysis indicates its possible classification in a glycolipids group. Results from crude oil solubilization assay showed that SdK644 strain biosurfactant was 2-fold greater than Tween 80 surfactant in crude oil solubilization and 12-fold higher than seawater control, as shown by GC-MS analysis of aliphatic compounds. Furthermore, this bioactive compound was shown to be nontoxic against Artemia larvae in short-term acute toxicity bioassay. Generally, the results showed the possible use of M. hydrocarbonoclasticus strain SdK644 biosurfactant in bioremediation processes of the marine environments.

No effect of N-acyl homoserine lactones disruption by lactonase enzyme on the virulence of Vibrio anguillarum towards sea bass (Dicentrarchus labrax) and brine shrimp (Artemia franciscana)

Quorum sensing (QS) is a bacterial communication system in which bacteria coordinate the expression of certain genes in response to the presence of small signal molecules. Some signal molecules called autoinducers are found to regulate several phenotypes of bacteria. The molecules used for the QS system of Vibrio anguillarum are supposed to regulate their pathogenic genes. However, it is not well understood how exactly the virulence gene of V. anguillarum is regulated by the QS molecules to date. To address this question, one of the QS molecules of the NB10 strain of V. anguillarum called N-acyl homoserine lactones (AHLs) was disrupted by a lactonase enzyme to verify its role on their virulence. The effects of AHLs degradation in vitro were investigated by measuring its effect on growth and virulence factors production (lipase, phospholipase, and caseinase) and in vivo by verifying its effect on sea bass and Artemia larvae infection. Lactonase enzyme degraded AHLs of NB10; yet that degradation had no effect on the cell growth and production of the tested virulence factors. Similarly, challenge tests demonstrated that larval mortality was not significantly lower by lactonase treatment. Therefore, these observations indicated that virulence gene expression of V. anguillarum and its virulence are not regulated by the AHL-mediated QS system; either different molecules or other factors are associated with the virulence regulation of V. anguillarum towards the tested life stages of sea bass and Artemia.

Developmental toxicity of Fe3O4 nanoparticles on cysts and three larval stages of Artemia salina

Using Artemia salina cysts (capsulated and decapsulated) and larvae (instar I, II and III) as experimental models, the potential effects of Fe3O4 nanoparticles (Fe3O4-NPs) on marine ecosystems were investigated. Hatchability, mortality and a number of ethological, morphological and biochemical parameters were selected as end-points to define the toxic responses. Data showed that the hatching rates of capsulated and decapsulated cysts were significantly decreased (p < 0.01) following exposure to 600 mg/L for 24 and 36 h. The LC50 values for instar II and III were 482 and 561 mg/L (could not be measured for instar I), and the EC50 values for swimming inhibition of instar I, II and III were 474, 365 and 421 mg/L, respectively. Effects on hatchability, mortality and swimming were accounted for Fe3O4-NPs rather than iron ion released from the NPs. Instar II larvae showed the greatest sensitivity to Fe3O4-NPs, and followed by instar III, instar I, decapsulated cysts and capsulated cysts. Body lengths of instar I, II and III larvae were decreased in dose-dependent manners. Fe3O4-NPs attached onto the gills and body surface, resulting in irreversible damages. Reactive oxygen species, malondialdehyde content, total antioxidant capacity and antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) activities were substantially increased following exposure, indicating that toxic effects were related to oxidative stress. Mitochondrial malformation, cristae rupturing and membranous structure disruption were clearly observed after Fe3O4-NPs exposure. Fe3O4-NPs were ingested and well distributed in the gut, yolk and primary body cavity. Uptake kinetics data showed that the maximum Fe3O4-NPs content (16.4 mg/g) was reached at 30 h. The combined results so far indicate that Fe3O4-NPs have the potential to affect aquatic organisms when released into the marine ecosystems.

Developmental toxicity of oxidized multi-walled carbon nanotubes on Artemia salina cysts and larvae: Uptake, accumulation, excretion and toxic responses

Using Artemia salina (A. salina) cysts (capsulated and decapsulated) and larvae [instar I (0–24 h), II (24–48 h) and III (48–72 h)] as experimental models, developmental toxicity of oxidized multi-walled carbon nanotubes (O-MWCNTs) was evaluated. Results revealed that hatchability of capsulated and decapsulated cysts was significantly decreased (p < 0.01) following exposure to 600 mg/L for 36 h. Mortality rates were 33.8, 55.7 and 40.7% for instar I, II and III larvae in 600 mg/L. The EC50 values for swimming inhibition of instar I, II and III were 535, 385 and 472 mg/L, respectively. Instar II showed the greatest sensitivity to O-MWCNTs, and followed by instar III, instar I, decapsulated cysts and capsulated cysts. Effects on hatchability, mortality and swimming were accounted for O-MWCNTs rather than metal catalyst impurities. Body length was decreased with the concentrations increased from 0 to 600 mg/L. O-MWCNTs attached onto the cysts, gill and body surface, resulting in irreversible damages. Reactive oxygen species, malondialdehyde content, total antioxidant capacity and antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) activities were increased following exposure, indicating that the effects were related to oxidative stress. O-MWCNTs were ingested and distributed in phagocyte, lipid vesicle and intestine. Most of the accumulated O-MWCNTs were excreted by A. salina at 72 h, but some still remained in the organism. Data of uptake kinetics showed that O-MWCNTs contents in A. salina were gradually increased from 1 to 48 h and followed by rapidly decreased from 48 to 72 h with a range from 5.5 to 28.1 mg/g. These results so far indicate that O-MWCNTs have the potential to affect aquatic organisms when released into the marine ecosystems.

Toxicity of α-Fe2O3 nanoparticles to Artemia salina cysts and three stages of larvae

Artemia salina cysts (capsulated and decapsulated) and larvae (instar I, II and III) were exposed to α-Fe2O3 nanoparticles (α-Fe2O3-NPs) to evaluate the effects on marine ecosystems. Hatchability, mortality and a number of ethological, morphological and biochemical parameters were selected as end-points to define the toxic responses. Results indicate that the hatchability of capsulated and decapsulated cysts was significantly decreased (p<0.01) following exposure to 600mg/L at 12, 18, 24 and 36h. Both increases of mortality and decreases of swimming speed were shown concentration-dependent manners. The LC50 values for instar II and III were 177.424 and 235.495mg/L, respectively (not calculable for instar I), the EC50 values for instar I, II and III were 259.956, 99.064 and 129.088mg/L, respectively. Instar II larvae show the greatest sensitive to α-Fe2O3-NPs, and followed by instar III, instar I, decapsulated cysts and capsulated cysts. Body lengths and individual dry weight of instar I, II and III larvae were decreased following exposure. α-Fe2O3-NPs attached onto the gills and body surface of larvae, resulting in irreversible damages. All of malondialdehyde content, total antioxidant capacity, reactive oxygen species and antioxidant enzymes activities were substantially increased in dose-dependent manners after exposure to α-Fe2O3-NPs suspensions, indicating that toxic effects were mediated by oxidative stress. Finally, the uptake result indicated that α-Fe2O3-NPs were ingested and distributed in the nephridial duct, primary body cavity and intestine of A. salina. Moreover, the uptake kinetics data show that the maximum α-Fe2O3-NPs content (8.818mg/g) was reached at 36h, and a steady state was reached after 60h. The combined results indicate that α-Fe2O3-NPs have the potential to affect aquatic life when released into the marine ecosystems.

Enhanced resistance against Vibrio harveyi infection by carvacrol and its association with the induction of heat shock protein 72 in gnotobiotic Artemia franciscana.

Induction of HSP72 is a natural response of stressed organisms that protects against many insults including bacterial diseases in farm (aquatic) animals. It would therefore be of great health benefit to search for natural compounds that are clinically safe yet able to induce HSP72 in animals. The phenolic compound carvacrol, an approved food component, had been shown in in vitro study to act as a co-inducer of HSP72, enhancing HSP72 production only in combination with a bona fide stress compared to the compound alone. However, in vitro model systems do not completely represent an in vivo physiology. Here, using the well-established gnotobiotic Artemia model system, we determined whether carvacrol could induce HSP72 in vivo, whether this putative effect could generate resistance in Artemia against biotic/abiotic stress and also unraveled the mechanism behind the possible HSP72-inducing effect of carvacrol. The gnotobiotic system is crucial for such studies because it avoids the interference of any extraneous factors on host-compound interaction. Here, carvacrol was shown to be a potent HSP72 inducer. Induction of HSP72 was associated with the generation of resistance in Artemia larvae against subsequent lethal heat stress or pathogenic Vibrio harveyi. Our results also provided new insight on the mode of HSP72 inducing action of carvacrol, in which the initial generation of reactive molecule H2O2 by the compound plays a key role. Overall results add new information about the bioactivity of carvacrol and advance our knowledge of this compound as potential prophylactic agent for controlling Vibrio infection in aquaculture animals.