Recent advances and future trends in zebrafish bioassays for aquatic ecotoxicology

Zebrafish (Danio rerio), a cyprinid teleost, has become an ideal model species for aquatic ecotoxicology due to the broad spectra of methodologies that have been developed since the 1980s. The zebrafish has many advantages as a model organism e.g. small size, ex utero development of the embryo, short reproductive cycle, and transparent embryos. In addition, the zebrafish shares a high degree of homology with the human genome. It has become a powerful model organism for genetics, development, environmental toxicology, several human diseases and pharmacology. Zebrafish bioassays can be used for environmental monitoring including pollutant evaluations, such as toxic heavy metals, endocrine disruptors, and organic pollutants. The large number of transparent embryos gained from zebrafish females, in vitro and rapid embryonic development and ready-to-use methods of biotechnology enables us to use mostly automatized high-throughput screening not only in pharmaceutical drug development protocols but in aquatic ecotoxicology as well

Evaluation of color intensity enhanced by paprika as feed additive in goldfish and koi carp using computer-assisted image analysis

Body color intensity of red-colored koi carp Cyprinus carpio and goldfish Carassius auratus auratus varieties were measured to evaluate the effect of paprika used as a feed additive. Digital photos of the experimental fish were processed and analyzed by using special software. The red, green and blue (RGB) values of images were recorded and grayscale values of R, G and B were analyzed. The RGB values seem to play different roles in the development of the visible 'redness' of the two species. In most cases the B values decreased continuously during the administration of the paprika as a carotenoid feed additive, which seemed to have no effect on this process. The G values remained unchanged or decreased slightly as redness increased due to paprika feeding. The R values had a tendency to increase due to paprika feeding but significant differences can be expected only after 4 weeks at the feeding conditions applied here. Both the initial rate of redness and genetic background are thought to influence the rate of red color intensity change, which was observed to be different in the two fish species studied here

Optimisation of Embryonic and Larval ECG Measurement in Zebrafish for Quantifying the Effect of QT Prolonging Drugs

Effective chemical compound toxicity screening is of paramount importance for safe cardiac drug development. Using mammals in preliminary screening for detection of cardiac dysfunction by electrocardiography (ECG) is costly and requires a large number of animals. Alternatively, zebrafish embryos can be used as the ECG waveform is similar to mammals, a minimal amount of chemical is necessary for drug testing, while embryos are abundant, inexpensive and represent replacement in animal research with reduced bioethical concerns. We demonstrate here the utility of pre-feeding stage zebrafish larvae in detection of cardiac dysfunction by electrocardiography. We have optimised an ECG recording system by addressing key parameters such as the form of immobilization, recording temperature, electrode positioning and developmental age. Furthermore, analysis of 3 days post fertilization (dpf) zebrafish embryos treated with known QT prolonging drugs such as terfenadine, verapamil and haloperidol led to reproducible detection of QT prolongation as previously shown for adult zebrafish. In addition, calculation of Z-factor scores revealed that the assay was sensitive and specific enough to detect large drug-induced changes in QTc intervals. Thus, the ECG recording system is a useful drug-screening tool to detect alteration to cardiac cycle components and secondary effects such as heart block and arrhythmias in zebrafish larvae before free feeding stage, and thus provides a suitable replacement for mammalian experimentation

Polyunsaturated fatty acids synergize with lipid droplet binding thalidomide analogs to induce oxidative stress in cancer cells

<p>Abstract</p> <p>Background</p> <p>Cytoplasmic lipid-droplets are common inclusions of eukaryotic cells. Lipid-droplet binding thalidomide analogs (2,6-dialkylphenyl-4/5-amino-substituted-5,6,7-trifluorophthalimides) with potent anticancer activities were synthesized.</p> <p>Results</p> <p>Cytotoxicity was detected in different cell lines including melanoma, leukemia, hepatocellular carcinoma, glioblastoma at micromolar concentrations. The synthesized analogs are non-toxic to adult animals up to 1 g/kg but are teratogenic to zebrafish embryos at micromolar concentrations with defects in the developing muscle. Treatment of tumor cells resulted in calcium release from the endoplasmic reticulum (ER), induction of reactive oxygen species (ROS), ER stress and cell death. Antioxidants could partially, while an intracellular calcium chelator almost completely diminish ROS production. Exogenous docosahexaenoic acid or eicosapentaenoic acid induced calcium release and ROS generation, and synergized with the analogs <it>in vitro</it>, while oleic acid had no such an effect. Gene expression analysis confirmed the induction of ER stress-mediated apoptosis pathway components, such as GADD153, ATF3, Luman/CREB3 and the ER-associated degradation-related HERPUD1 genes. Tumor suppressors, P53, LATS2 and ING3 were also up-regulated in various cell lines after drug treatment. Amino-phthalimides down-regulated the expression of CCL2, which is implicated in tumor metastasis and angiogenesis.</p> <p>Conclusions</p> <p>Because of the anticancer, anti-angiogenic action and the wide range of applicability of the immunomodulatory drugs, including thalidomide analogs, lipid droplet-binding members of this family could represent a new class of agents by affecting ER-membrane integrity and perturbations of ER homeostasis.</p

Detection of electrocardiographic signal.

<p>A) Depiction of an electrocardiogram and associated components, created using Adobe Photoshop CS6, B) 2 second section of a raw ECG recording from a larval zebrafish (3 dpf) without digital filtering, C) digitally filtered version of the ECG recording using low pass filtering to reduce background noise and produce a waveform suitable for analysis, D) analysed trace showing waveform reproducibility and stability during the recording period, with each line representing one cardiac cycle. The dark line in the middle represents the mean of all cycles from a 1 minute record.</p

Z-factor scores for different treatment regimes.

<p>Z-factor scores for different treatment regimes.</p

Optimisation of ECG recording system.

<p>A) Mean ECG interval measurements obtained from 3 dpf larvae following exposure to different ambient temperatures (n = 10), and B) over different developmental periods (2, 3, 4 and 5 days; n = 8).</p