Life Cycle Stages and Length of Zebrafish (Danio rerio) Exposed to DDT

Abstract

Long-term toxicity growth tests were conducted with DDT using zebrafish (Danio rerio). The fish were exposed to concentrations of 0.05 µg/l, 0.5 µg/l, 5 µg/l and 50 µg/l DDT under flow-through conditions. The effect of the compound on the ecologically important parameters hatching rate, duration of the developmental stages and growth were the focus of interest. When exposed to 50 µg/l DDT, the hatching rate was 2 to 3 times lower than in embryos exposed to 0.05 µg/l DDT. This study demonstrates that the rearing zebrafish in the pesticide causes a reduction in body length and the durations of the life cycle stages (LCS) of the offspring are extended. These effects are increased when the fish are exposed to higher DDT concentrations.Key words ---Danio rerio, early life stage, life cycle stages, growth, F 1 -generation, DDT able up to now. The zebrafish [Danio rerio (D. rerio)] is a suitable model for full life cycle assessments because zebrafish takes only 3-4 months to reach the sexual maturity. Moreover, they can be maintained in a laboratory environment at low cost and remain sexually active throughout the year.The test employed in this study involved exposure of zebrafish to the toxin from the fertilized egg up to the mature animal. The effect on reproduction was assessed by examination of mortality, hatching rate, body length and development of the offspring. This study encompassed the examination of two generations of fish over a period of approximately 8 months. This was regarded necessary to obtain sufficient information on the duration of each life stage and the deleterious effect of the chemical on the subsequent generation. The parameters were also investigated in the offspring of exposed parents that were subsequently reared in a toxin-free environment. The second generation was assessed up to six weeks and the difference with offspring which remained exposed to DDT was determined.

Sublethal effects of carbaryl on embryonic and gonadal developments of zebrafishDanio rerio

“…In a separate study (Adhikari et al 2006), it was reported that cypermethrin concentrations of between 0.4 and 0.8 mg l -1 reduced the total number of spawned eggs, percentage fertilisation and hatching success in the freshwater fish Labeo rohita. DDT concentrations of between 0.00005 and 0.05 mg l -1 have also been reported to cause up to 65% reduction in hatching rate in Danio rerio (Njiwa et al 2003). These results imply that carbaryl may have some teratogenic effects on zebrafish embryos, confirming the reports by Solomon and Weis (2005) and Teraoka et al (2006).…”

The toxic potential of aldrin and heptachlor on Danio rerio juveniles (Cypriniformes, Cyprinidae)

“…These authors suggested two hypotheses to explain the higher weights of D. rerio at intermediate concentrations of 4-Chloroaniline: 1) because low concentrations are sufficient to saturate binding sites, culminating in toxic effects; and 2) because high concentrations may cause disturbances at other sites, presenting equivalent results. In contrast, the study of Njiwa et al (2004) on the toxicity of DDT on the initial life cycle phases of D. rerio demonstrated reduced rates of egg hatching, growth and survival and an increase in the duration of the life cycles with progressive increase in DDT concentrations. The second generation of fish (F2), produced by a generation already contaminated with DDT, suffered more intensely from the compound's effects.…”

Maternal transfer of xenobiotics and effects on larval striped bass in the San Francisco Estuary

“…Concentrations of individual contaminants and mixtures determined in this study have been shown to have adverse effects in a wide range of animals, including mammals, reptiles, amphibians, and fish (20)(21)(22)(23). Some of the effects described are as follows: alterations of growth and development (24), poor hatching success (22), alterations of the reproductive and nervous system (25,26), learning and behavioral deficits retained throughout life (27,28), abnormalities of the liver and other organ systems (29,30), and endocrine disruption (29,31). Studies have also shown that these contaminants in combination can increase adverse effects by several orders of magnitude (32,33).…”