Hypoxia-inducible factor (HIF) is an important transcription factor under hypoxic condition in many organisms, and plays a key role in the induction of hypoxia tolerance. It is necessary to establish a hypoxia model for HIF and to perform further hypoxia tolerance research. To investigate the value of Daphnia as a model organism in hypoxia precondition, we developed a preconditioning protocol with a model organism, Daphnia pulex. We found that two episodes of exposure to hypoxic solution resulted in enhanced hypoxia tolerance which is dependent on HIF. Comparative genomic analysis was also made to highlight the homology of HIF-related genes among Daphnia, fruitfly and human. We found that Daphnia is suitable for the study of human hypoxic injury as a model organism.
Adaptation, Physiological ; genetics ; Amino Acid Sequence ; Animals ; Cladocera ; genetics ; Culture Techniques ; Daphnia ; genetics ; Disease Models, Animal ; Hypoxia ; genetics ; metabolism ; Hypoxia-Inducible Factor 1 ; genetics ; Ischemic Preconditioning ; methods ; Molecular Sequence Data

The objective of this study was to determine toxicities of four parabens (methyl paraben, MP; ethyl paraben, EP; n-propyl paraben, PP; and n-butyl paraben; BP) and their mixtures to two aquatic microorganisms, Daphnia magna and Aliivibrio fischeri. Parabens are one of the widely used preservatives for personal care products, such as cosmetics, pharmaceuticals and food also. First, each paraben was treated to D. magna to measure the toxicity levels as LC₂₀ and LC₅₀. The results showed their value of MP (25.2 mg/L, 73.4 mg/L), EP (18.4 mg/L, 43.7 mg/L), PP (10.4 mg/L, 21.1 mg/L) and BP (3.3 mg/L, 11.2 mg/L). Then, each of the parabens was treated to A. fischeri and calculated their EC₂₀ and EC₅₀ by bioluminescence inhibition test. The results showed the values of MP (2.93 mg/L, 16.8 mg/L), EP (1.18 mg/L, 6.74 mg/L), PP (0.51 mg/L, 5.85 mg/L) and BP (0.21 mg/L, 2.34 mg/L). These four parabens belong to the group classified as being ‘harmful to aquatic organisms’ (above 10 mg/L, below 100 mg/L). After measuring the toxicity, EC₂₀ values of two or more parabens were tested in order to investigate their toxicity. A total of ten combinations of four parabens were tested. As a result, the bioluminescence inhibition test of A. fischeri showed that the toxicity of mixture parabens was stronger than that of a single compound and combinations of three parabens showed the highest bioluminescence inhibition. These results showed that independent toxicity of paraben was maintained. Therefore, it can be predictable that the toxicity of paraben is getting stronger by the addition of other parabens.
Aliivibrio fischeri* ; Aliivibrio* ; Daphnia* ; Humans ; Parabens*

The objective of this study was to determine toxicities of four parabens (methyl paraben, MP; ethyl paraben, EP; n-propyl paraben, PP; and n-butyl paraben; BP) and their mixtures to two aquatic microorganisms, Daphnia magna and Aliivibrio fischeri. Parabens are one of the widely used preservatives for personal care products, such as cosmetics, pharmaceuticals and food also. First, each paraben was treated to D. magna to measure the toxicity levels as LC₂₀ and LC₅₀. The results showed their value of MP (25.2 mg/L, 73.4 mg/L), EP (18.4 mg/L, 43.7 mg/L), PP (10.4 mg/L, 21.1 mg/L) and BP (3.3 mg/L, 11.2 mg/L). Then, each of the parabens was treated to A. fischeri and calculated their EC₂₀ and EC₅₀ by bioluminescence inhibition test. The results showed the values of MP (2.93 mg/L, 16.8 mg/L), EP (1.18 mg/L, 6.74 mg/L), PP (0.51 mg/L, 5.85 mg/L) and BP (0.21 mg/L, 2.34 mg/L). These four parabens belong to the group classified as being ‘harmful to aquatic organisms’ (above 10 mg/L, below 100 mg/L). After measuring the toxicity, EC₂₀ values of two or more parabens were tested in order to investigate their toxicity. A total of ten combinations of four parabens were tested. As a result, the bioluminescence inhibition test of A. fischeri showed that the toxicity of mixture parabens was stronger than that of a single compound and combinations of three parabens showed the highest bioluminescence inhibition. These results showed that independent toxicity of paraben was maintained. Therefore, it can be predictable that the toxicity of paraben is getting stronger by the addition of other parabens.
Aliivibrio fischeri ; Aliivibrio ; Daphnia ; Humans ; Parabens

OBJECTIVES: Titanium dioxide (TiO2), a common nanoparticle widely used in industrial production, is one of nano-sized materials. The purpose of this study was to determine the acute and chronic toxicity of TiO2 using different size and various concentrations on Daphnia magna. METHODS: In the acute toxicity test, four concentrations (0, 0.5, 4, and 8 mM) for TiO2 with 250 or 500 nm and five concentrations (0, 0.25, 0.5, 0.75, and 1 mM) for TiO2 with 21 nm were selected to analyze the toxic effect to three groups of ten daphnia neonates over 96 hours. In addition, to better understand their toxicity, chronic toxicity was examined over 21 days using 0, 1, and 10 mM for each type of TiO2. RESULTS: Our results showed that all organisms died before the reproduction time at a concentration of 10 mM of TiO2. In addition, the exposure of anatase (21 nm) particles were more toxic to D. magna, comparing with that of anatase (250 nm) and rutile (500 nm) particles. CONCLUSIONS: This study indicated that TiO2 had adverse impacts on the survival, growth and reproduction of D. magna after the 21days exposure. In addition, the number of test organisms that were able to reproduce neonates gradually were reduced as the size of TiO2 tested was decreased.
Daphnia ; Humans ; Infant, Newborn ; Nanoparticles ; Reproduction ; Titanium ; Toxicity Tests, Acute

OBJECTIVES: An ecofriendly alternative to chemical pesticides is bio-pesticides, which are derived from natural sources. The interest in bio-pesticides is based on the disadvantages associated with chemical pesticides. METHODS: We conducted acute toxicity assessments of camphor, a major component of bio-pesticides, by using Daphnia magna (D. magna) as well as assessed the morphological abnormalities that occurred in Danio rerio (D. rerio) embryos. RESULTS: The median effective concentration of camphor on D. magna after 48 hours was 395.0 muM, and the median lethal concentration on D. rerio embryos after 96 hours was 838.6 muM. The no observed effect concentration and predicted no effect concentration of camphor on D. magna, which was more sensitive than D. rerio, were calculated as 55.2 muM and 3.95 muM, respectively. Morphological abnormalities in D. rerio embryos exposed to camphor increased over time. Coagulation, delayed hatching, yolk sac edema, pericardial edema, and pigmentation of embryos mainly appeared between 24 and 48 hours. Further, symptoms of scoliosis and head edema occurred after 72 hours. In addition, bent tails, ocular defects and collapsed symptoms of fertilized embryonic tissue were observed after 96 hours. CONCLUSIONS: The camphor toxicity results suggest that continuous observations on the ecosystem are necessary to monitor toxicity in areas where biological pesticides containing camphor are sprayed.
Camphor* ; Daphnia* ; Ecosystem ; Edema ; Embryonic Structures ; Head ; Pesticides ; Pigmentation ; Scoliosis ; Yolk Sac ; Zebrafish*

OBJECTIVES: Tricalcium phosphate and calcium hydrogenorthophosphate are high production volume chemicals, mainly used as foodstuff additives, pharmaceuticals, lubricants, synthetic resin, and disinfectants. Phosphate has the potential to cause increased algal growth leading to eutrophication in the aquatic environment. However, there is no adequate information available on risk assessment or acute and chronic toxicity. The aim of this research is to evaluate the toxic potential of phosphate compounds in the aquatic environment. METHODS: An aquatic toxicity test of phosphate was conducted, and its physico-chemical properties were obtained from a database recommended in the Organization for Economic Cooperation and Development (OECD) guidance manual. An ecotoxicity test using fish, Daphnia, and algae was conducted by the good laboratory practice facility according to the OECD TG guidelines for testing of chemicals, to secure reliable data. RESULTS: The results of the ecotoxicity tests of tricalcium phosphate and calcium hydrogenorthophosphate are as follows: In an acute toxicity test with Oryzias latipes, 96 hr 50% lethal concentration (LC50) was >100 (measured:>2.14) mg/L and >100 (measured: >13.5) mg/L, respectively. In the Daphnia test, 48 hr 50% effective concentration (EC50) was >100 (measured: >5.35) mg/L and >100 (measured: >2.9) mg/L, respectively. In a growth inhibition test with Pseudokirchneriella subcapitata, 72 hr EC50 was >100 (measured: >1.56) mg/L and >100 (measured: >4.4) mg/L, respectively. CONCLUSIONS: Based on the results of the ecotoxicity test of phosphate using fish, Daphnia, and algae, L(E)C50 was above 100 mg/L (nominal), indicating no toxicity. In general, the total phosphorus concentration including phosphate in rivers and lakes reaches levels of several ppm, suggesting that phosphate has no toxic effects. However, excessive inflow of phosphate into aquatic ecosystems has the potential to cause eutrophication due to algal growth.
Calcium ; Daphnia ; Disinfectants ; Ecosystem ; Eutrophication ; Lakes ; Lubricants ; Oryzias ; Phosphorus ; Resins, Synthetic ; Risk Assessment ; Rivers ; Toxicity Tests ; Toxicity Tests, Acute

The mechanisms of general anesthesia, which was introduced about 170 years ago, remain poorly under- stood. Even less well understood are the effects of general anesthesia on the human body. Recently we identified 18 G-protein coupled receptor (GPCR) genes of Daphnia pulex, an invertebrate model organism. Phylogenetic analysis identified these genes to be the homologs of the human γ-aminobutyric acid, type B (GABAB) receptor, metabotropic glutamate receptors (mGluR), adrenergic receptor, serotonin (5-HT) receptor, dopamine receptor and muscarinic acetylcholine receptor (mAChR). Using reverse transcription and quantitative PCR techniques, we systematically measured the effects of propofol, etomidate and ethanol on these 18 GPCR mRNA expressions in Daphnia pulex.
Animals ; Daphnia ; drug effects ; metabolism ; Ethanol ; pharmacology ; Etomidate ; pharmacology ; Phylogeny ; Propofol ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Receptors, GABA-B ; genetics ; metabolism

Objective To establish a Daphnia model of alloxan-induced diabetes. Methods Daphnia were exposed to three different concentrations of alloxan (3, 5, and 10 mmol/L) for 30 minutes. Blood glucose and survival rate were recorded for 72 hours after alloxan insult. Sequence analysis and phylogenetic inference for glucose transporters (GLUT) were clustered with the maximum-likelihood method. Using reverse transcription and quantitative polymerase chain reaction techniques, we investigated the transcriptional changes of GLUT at 12 hours after alloxan (5 mmol/L) exposure. Results Compared with control, 3 mmol/L, and 5 mmol/L as well as 10 mmol/L alloxan initially induced transient blood glucose decline by 15% for 2 hours and 12 hours respectively. In Daphnia with 5 and 10 mmol/L alloxan, their blood glucose was persistently raised by about 150% since after 24-hour insult. Survival rate of Daphnia exposure to alloxan with concentrations of 3, 5, and 10 mmol/L were 90%, 75%, and 25% respectively. We predicted seven GLUT genes in the Daphnia genome and successfully amplified them using real-time polymerase chain reaction. Two of seven GLUT transcripts were down-regulated in Daphnia with 5 mmol/L alloxan-induced diabetes. Conclusion Alloxan-induced diabetes model was successfully established in the Daphnia pulex, suggesting diabetes-relevant experiments can be conducted using Daphnia.
Alloxan ; Animals ; Blood Glucose ; analysis ; Daphnia ; Diabetes Mellitus, Experimental ; chemically induced ; physiopathology ; Disease Models, Animal ; Gene Expression Regulation ; Glucose Transport Proteins, Facilitative ; genetics ; metabolism ; Likelihood Functions ; Phylogeny ; Real-Time Polymerase Chain Reaction

The HPLC and TLC retention, n-octanol/water partition coefficients (log Kow), bioconcentration factors, and acute toxicity data of 29 heteroatomic polycyclic aromatic hydrocarbons and 7 parent polycyclic aromatics were determined experimentally. For the same set of compounds, molecular weights, fragmental log Kow values, and molecular connectivities were calculated. Quantitation of the mathematical relationships between the variables was used to validate the predictive potential of various parameters. The importance of log Kow in predictive studies is highlighted. It is concluded that the internal concentration of a pollutant in the organism should be used as a parameter in future QSAR work.
1-Octanol ; Animals ; Chromatography, High Pressure Liquid ; Chromatography, Thin Layer ; Daphnia ; drug effects ; Ecology ; Environmental Pollution ; prevention & control ; Octanols ; Photobacterium ; drug effects ; Poecilia ; metabolism ; Polycyclic Compounds ; metabolism ; toxicity ; Regression Analysis ; Solubility ; Structure-Activity Relationship ; Water

pH homeostasis is essential for development, proliferation and apoptosis of cells. Once the pH balances are broken, cell functions and survival will be affected. Nevertheless, moderate acidosis could result in adaptive responses for cell survival and increase tolerance to harmful stress. Here we found that acidic preconditioning (APC) could significantly increase the survival rate of Daphnia pulex, a freshwater invertebrate, during severe hypoxic insult. Meanwhile, the acidic treatment significantly increased the gene expression of hypoxia inducible factor (HIF). Both echinomycin, an inhibitor of HIF, and compound C, an inhibitor of AMP-activated protein kinase (AMPK), could effectively eliminate the acid-induced hypoxic tolerance and the enhanced transcription of HIF. Temsirolimus, an inhibitor of mammalian Target of Rapamycin (mTOR), though effectively abolished the increased transcription of HIF, improved the APC-mediated protection. This result suggests that the involvement of the HIF and AMPK and mTOR could signal the pathways in APC-induced protection against hypoxic insult.
AMP-Activated Protein Kinases ; antagonists & inhibitors ; Acids ; pharmacology ; Adaptation, Physiological ; Animals ; Daphnia ; genetics ; physiology ; Hypoxia ; physiopathology ; Hypoxia-Inducible Factor 1 ; genetics ; metabolism ; Ischemic Preconditioning ; methods ; Pyrazoles ; pharmacology ; Pyrimidines ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Sirolimus ; analogs & derivatives ; pharmacology ; TOR Serine-Threonine Kinases ; antagonists & inhibitors