Xenobiotic-induced changes in the arginase activity of zebrafish (Danio rerio) eleutheroembryo

Vascular Damage in Obesity and Diabetes: Highlighting Links Between Endothelial Dysfunction and Metabolic Disease in Zebrafish and Man

Endothelial dysfunction is an initial pathophysiological mechanism of vascular damage and is further recognized as an independent predictor of negative prognosis in diabetes-induced micro- and macrovascular complications. Insight into the capability of zebrafish to model metabolic disease like obesity and type II diabetes has increased and new evidence on the induction of vascular pathologies in zebrafish through metabolic disease is available. Here, we raise the question, if zebrafish can be utilized to study the initial impairments of vascular complications in metabolic disorders. In this review, we focus on the advances made to develop models of obesity and type II diabetes in zebrafish, discuss the key points and characteristics of these models, while highlighting the available information linked to the development of endothelial dysfunction in zebrafish and man. We show that larval and adult zebrafish develop metabolic dysregulation in the settings of obesity and diabetes, exhibiting pathophysiological mechanisms, which mimic the human condition. The most important genes related to endothelial dysfunction are present in zebrafish and further display similar functions as in mammals. Several suggested contributors to endothelial dysfunction found in these models, namely hyperinsulinaemia, hyperglycaemia, hyperlipidaemia and hyperleptinaemia are highlighted and the available data from zebrafish are summarised. Many underlying processes of endothelial dysfunction in obesity and diabetes are fundamentally present in zebrafish and provide ground for the assumption, that zebrafish can develop endothelial dysfunction. Conservation of basic biological mechanisms is established for zebrafish, but focused investigation on the subject is now needed as validation and particularly more research is necessary to understand the differences between zebrafish and man. The available data demonstrate the relevance of zebrafish as a model for metabolic disease and their ability to become a proponent for the investigation of vascular damage in the settings of obesity and diabetes.

The impact of kraft pulping effluent on egg survival and hatching success in two species of Clupeiformes (Teleostei)

The anchoveta (Engraulis ringens) and sardine (Strangomera bentincki) are coastal pelagic species with important spawning areas off the coast of Chile. The discharge of secondary-treated effluents from a kraft pulp plant near one of these spawning areas has raised environmental concerns. Therefore, effluent effects on the development of anchoveta and sardine eggs were assessed by in vitro exposure. Eggs were sampled between 2007 and 2010 off Talcahuano, Chile. Subsequent toxicity tests (96 h duration, 12 °C) were performed using increasing effluent concentrations, a filtered seawater control, and two potassium dichromate concentrations (to verify consistent embryonic sensitivity). Egg mortality and hatching success were evaluated. For anchoveta, mortality (9.9 ± 7.1%) did not significantly differ among groups in five toxicity tests except the final toxicity test that showed significant differences in mortality (5.6% control vs 27.8% in 100% effluent). For sardines, no differences in mortality existed between the effluent dilutions (2.6 ± 3.6%) and control (6.3 ± 3.9%). Notably, anchoveta egg survival and hatching success rates were inconsistent, i.e., the highest rates of hatching failure occurred on the same sampling date with the highest rates of survival for the 100% effluent group (72%). In conclusion, the obtained results indicate that (i) anchoveta egg mortality and hatching failure increase only under 100% effluent exposure, coinciding with decreased egg quality near the end of spawning season and (ii) high effluent dilutions not significantly increase sardine and anchoveta egg mortalities. Nevertheless, the recorded adverse effects to the hatching process should be studied in greater detail, particularly considering interspecific variability and the complexity of reproductive processes, especially during early development.

Gas chromatography-mass spectrometry for metabolite profiling of Japanese medaka (Oryzias latipes) juveniles exposed to malathion

PURPOSE

We evaluate malathion toxicity to Japanese medaka (Oryzias latipes) juveniles by using a mass spectrometry combined with gas chromatography (GC/MS) metabolomics approach.

METHODS

Medaka were exposed to low (L) and high (H) concentrations (nominally 20 and 2,000 μg/L, respectively) of water-borne malathion. Metabolites were extracted from the fish, derivatized, and analyzed by GC/MS. Identified metabolites were subjected to one-way analysis of variance and principal component analysis (PCA). We examined the variations in the amounts of the metabolites during the exposure period.

RESULTS AND DISCUSSION

At 24 h, control, L, and H groups were separated along PC1, suggesting that the effects of malathion depended on exposure concentration. The PCA results at 96 h suggest that the metabolite profiles variations of the L and H groups differed, and thus that the effects of malathion in groups differed. At 24 h, the amounts of amino acids in both exposed groups were lower than the control group amounts, perhaps owing to accelerated protein synthesis. At 96 h, the amounts of almost all the amino acids increased in the L group but decreased in the H group relative to the control group amounts, suggesting the proteolysis occurred in the L group while protein synthesis continued in the H group, that the high malathion exposure affected the fish. In addition, at 96 h, gluconeogenesis may have been induced in the L group but not in H group.

CONCLUSIONS

Malathion exposure may have altered the balance between protein synthesis and degradation and induced gluconeogenesis in medaka. Our results suggest that metabolomics will be useful for comprehensive evaluation of toxicity.