Zebra fish toxicity testing

Ciba-Geigy Ltd (1993d) Report on the acute toxicity test of irgastab 17 MOK-S to zebra-fish (Brachydanio rerio). Basel, Ciba-Geigy Ltd, 27 July (Test No. 928312). 

Hooftman RN, de Wolf JM (2003b) Trichloromethylstannane (CAS 993-16-8) Semi-static acute toxicity test with the zebra fish Brachydanio rerio. Zeist, TNO, May (Report No. V2492/03). 

Embryonic zebra fish model was employed to study fullerene toxicity. This model is quite convenient because the embryos are transparent in the first week of life and their rate of development is rather fast. C60, C70, and C60(OH)24 have been tested on early embryogenesis (Usenko et al., 2007), presenting effects on this process with malformations, pericardial edema, and mortality. The results for fullerols are milder, but it is difficult to attribute this effect to the presence of the functionalizations themselves or to the easier solubilization, implying diminished cluster formations and avoiding the use of solvents as toluene or THF, the presence of which can play an important role in toxicity, as already demonstrated. 

Roseth, S., Edvardsson, T., Botten, T.M., Fuglestad, J., Fonnum, F. and Stenersen, J. (1996) Comparison of acute toxicity of process chemicals used in the oil refinery industry, tested with the diatom Chaetoceros gracilis, the flagellate Isochrysis galbana, and the zebra fish, Brachydanio rerio, Environmental Toxicology and Chemistry 15 (7), 1211-1217. 

Scholz S., Fisher S., Gundel U., Kuster E., Luckenbach T. Voelker D. (2008) The zebra fish embryo model in environmental risk assessment - application beyond acute toxicity testing. Environmental Science and Pollution Research International 15 394-404. 

Neilson, A.H., A.S. Allard, S. Fischer, M. Malmberg and T. Viktor. Incorporation of a subacute test with zebra fish into a hierarchical system for evaluating the effect of toxicants in the aquatic environment. 

The presence of Ca2+ or Mg2+ cations in test media of appreciable hardness may introduce complications due to complex formation with the toxicant or, in extreme cases, formation of precipitates which make it impossible to carry out the test. One example of this is provided by 2,5-dichloro-3,6-dihydroxybenzo-l,4-quinone which could be examined in the zebra fish system although not in the Ceriodaphnia dubia system using dilution media of greater hardness (Remberger et al. 1991). The additional sigificance of ionic strength is noted briefly in Section 7.3.1.4. 

It is important to appreciate methodological differences in the procedures by which tests for subacute toxicity are carried out, and differences in the results that may be obtained with fish having different reproduction strategies. The two test protocols for zebra fish may be used as illustration of the first, and the divergent results for a single substance using zebra fish and guppy used as illustration of the second. 

In one protocol using zebra fish, the spawn from unexposed adults are collected, the fertilization rate determined after 24 h and the test continued with fertilized ova the survival rate and body length of the larvae are then determined after 6 weeks during which time the larvae are exposed to the toxicant and provided with food (Nagel et al. 1991). 

In an alternative procedure also using zebra fish, the end point is the median survival time of the larvae which are exposed to the toxicant but are not provided with food the termination of the test is determined by the time of survival that may be achieved by ingestion of the yolk sac (Landner et al. 1985). In these experiments, food is withheld for two specific reasons to inhibit growth of microorganisms particularly in industrial effluents which have been treated biologically and to circumvent the possibility of sorption of the toxicant to the food. 

Bresch, H., H. Beck, D. Ehlermann, H. Schlaszus, and M. Urbanek. 1990. A long-term toxicity test comprising reproduction and growth of zebra fish with 4-chloroaniline. Arch. Environ. Contam. Toxicol. 19 419-427. 

This test is conducted on zebra fish (Brachydanio rerio). Acute toxicity is expressed as the median lethal concentration (LC q), that is, the concentration (mg.l) required to kill 50% of the fish exposed for a specific duration (preferably 90 h). After exposure, the deaths are recorded every 24 h and the LCjq is calculated statistically after each observation. 

HWS exhibited a potent inhibitory potency against dicot plant (pea) PDHc, which was consistent with its good selectivity against dicotyledonous weeds. HWS has a very weak inhibitoiy potency against PDHc fi om mammal (pig heart) (Chap. 7). HWS also has a low acute toxicity profile against rat and other tested animals. It is safe to non-target species, such as honey bee, quad, zebra fish, and silkworm. 

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