Abstract:The zebrafish embryo is a useful small model for investigating vertebrate development because of its transparency, low cost, transgenic and morpholino capabilities, conservation of cell signaling, and concordance with mammalian developmental phenotypes. From these advantages, the zebrafish embryo has been considered as an alternative model for traditional in vivo developmental toxicity screening. The use of this organism in conjunction with traditional in vivo developmental toxicity testing has the potential t… Show more
“…Zebrafish have become a preferred toxicity model due to their rapid life cycle, high fecundity, transparent development, and their embryos being amenable to genetic manipulation using transgenic approaches and morpholino gene knockdowns (Sipes et al, 2011). Another important attribute is that sequencing of the zebrafish genome has shown more than 80% of zebrafish genes are homologous to human genes.…”
-Herein, we report on the joint toxicity of four fluoroquinolones and two tetracyclines (β-diketone antibiotics-DKAs) to zebrafish based on a series of toxicological endpoints and histopathological observations. A positive dose-dependence was observed in DKA-exposure groups with a 72-hpf EC 50 of 130.3 mg/L for hatching rate, 120-hpf LC 50 of 149.8 mg/L, and 120-hpf EC 50 of 135.1 mg/L for malformation rate. When zebrafish at 60 dpf were exposed to a series of DKA concentrations (45, 60 and 90 mg/L) for 7, 14 and 21 days, creatine kinase and AChE activities were significantly induced, and intracellular malondialdehyde increased in all treatments except for the 45 mg/L treatment. The transcription levels of AHRRa from livers were significantly (p < 0.05) up-regulated in all treatments after two months of DKA exposure. CKma expression from skeletal muscle was significantly down-regulated in the 90 mg/L treatment. A remarkable down-regulation of CYP3A65 was observed in the 60 mg/L treatment. DKA exposure resulted in severe tissue damage including mitochondria swelling, reduction of mitochondrial cristae, deepening of mitochondrial cristae bands, and decreasing and even disappearance of the rough endoplasmic reticulum. Total sperm motility was decreased by ca. 30% due to DKA exposure. These results provide important information for toxicity and health risks due to mixed DKA exposure in aquatic environments.
“…Zebrafish have become a preferred toxicity model due to their rapid life cycle, high fecundity, transparent development, and their embryos being amenable to genetic manipulation using transgenic approaches and morpholino gene knockdowns (Sipes et al, 2011). Another important attribute is that sequencing of the zebrafish genome has shown more than 80% of zebrafish genes are homologous to human genes.…”
-Herein, we report on the joint toxicity of four fluoroquinolones and two tetracyclines (β-diketone antibiotics-DKAs) to zebrafish based on a series of toxicological endpoints and histopathological observations. A positive dose-dependence was observed in DKA-exposure groups with a 72-hpf EC 50 of 130.3 mg/L for hatching rate, 120-hpf LC 50 of 149.8 mg/L, and 120-hpf EC 50 of 135.1 mg/L for malformation rate. When zebrafish at 60 dpf were exposed to a series of DKA concentrations (45, 60 and 90 mg/L) for 7, 14 and 21 days, creatine kinase and AChE activities were significantly induced, and intracellular malondialdehyde increased in all treatments except for the 45 mg/L treatment. The transcription levels of AHRRa from livers were significantly (p < 0.05) up-regulated in all treatments after two months of DKA exposure. CKma expression from skeletal muscle was significantly down-regulated in the 90 mg/L treatment. A remarkable down-regulation of CYP3A65 was observed in the 60 mg/L treatment. DKA exposure resulted in severe tissue damage including mitochondria swelling, reduction of mitochondrial cristae, deepening of mitochondrial cristae bands, and decreasing and even disappearance of the rough endoplasmic reticulum. Total sperm motility was decreased by ca. 30% due to DKA exposure. These results provide important information for toxicity and health risks due to mixed DKA exposure in aquatic environments.
“…We utilized zebrafish to analyze if FIB could be used to indicate dangers to aquatic vertebrates living within these waters. Zebrafish, being small in size, having a short reproductive cycle, and producing large broods of transparent embryos, have become a powerful model organism to study environmental toxicology [33]- [36]. Due to this, zebrafish have been frequently used in eco-environmental monitoring and pollutant evaluations involving toxic heavy metals, endocrine disruptors, and organic pollutants [37]- [39].…”
Many studies report the relationship between coliform indicator bacteria levels and the overall quality of environmental water for public use. This study, an outgrowth of a long-term watermonitoring program within the upper Appomattox River (Virginia) watershed, employs a zebrafish model to examine the relationship between impaired stream water and aquatic vertebrate development. We report results that suggest an expansion of the indicator bacteria concept, showing a possible relationship between waters containing high levels of the indicator bacterium, Escherichia coli (E. coli), with developmental defects upon zebrafish embryos. These effects are not directly attributable to bacterial presence, as filtered test waters void of bacteria produce the same results in embryos, indicating these developmental defects are due to the presence of other toxins or contaminants. Fish embryos exposed to the test waters show reduced survivorship and altered brain and heart development. Furthermore, fish surviving to adulthood exhibit altered gonads and skewed sex ratios. We suggest that this broadly focused approach examining the complex interactions (biotic and abiotic) within raw water sources could be used in conjunction with traditional chemical assays and/or dose-response studies on vertebrate models for a more complete analysis of stream water quality conditions.
“…This animal has been used in numerous studies of developmental or environmental toxicology. 18,19 In addition, the Zebrafish embryo has been shown to be adversely effected by various physical insults, including heat and vibration. 20,21 The transparency of the embryos and availability of specific antibody staining allows the detailed investigation of axonal and neuronal development, 22,23 and may provide a means to study complex human conditions, such as autism.…”
A system for scanning zebrafish embryos with diagnostic ultrasound was developed for research into possible biological effects during development. Two troughs for holding embryos were formed from agarose in a rectangular dish and separated by an ultrasound absorber. A 4.9 MHz linear array ultrasound probe was positioned to uniformly scan all the embryos at the bottom of one trough, with the other used for controls. Zebrafish embryos were scanned continuously from 10-24 h post fertilization (hpf ) during the segmentation period and gross morphological parameters were measured at 30 hpf, including viability, length, number of visible axons, and the progression of the lateral line primordium (LLP). Our initial tests were encumbered by the thermal effects of probe self-heating, which resulted in accelerated development of the zebrafish embryos. After subsequent optimization, our test revealed a significant retardation of primary motor axons and the migration of the LLP in embryos scanned with ultrasound, which indicated a potential for nonthermal effects on neuronal development. This diagnostic ultrasound exposure system is suitable for further investigation of possible subtle bioeffects, such as perturbation of neuronal migration.
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