Molecular Responses of Daphnids to Chronic Exposures to Pharmaceuticals

Abstract

Pharmaceutical compounds are among several classes of contaminants of emerging concern, such as pesticides, heavy metals and personal care products, all of which are a major concern for aquatic ecosystems. The hazards posed by the presence of pharmaceutical is one which affects both freshwater organisms and human health—via non-target effects and by the contamination of drinking water sources. The molecular and phenotypic alterations of five pharmaceuticals which are commonly present in the aquatic environment were explored in daphnids under chronic exposures. Markers of physiology such as enzyme activities were combined with metabolic perturbations to assess the impact of metformin, diclofenac, gabapentin, carbamazepine and gemfibrozil on daphnids. Enzyme activity of markers of physiology included phosphatases, lipase, peptidase, β-galactosidase, lactate dehydrogenase, glutathione-S-transferase and glutathione reductase activities. Furthermore, targeted LC-MS/MS analysis focusing on glycolysis, the pentose phosphate pathway and the TCA cycle intermediates was performed to assess metabolic alterations. Exposure to pharmaceuticals resulted in the changes in activity for several enzymes of metabolism and the detoxification enzyme glutathione-S-transferase. Metabolic perturbations on key pathways revealed distinct groups and metabolic fingerprints for the different exposures and their mixtures. Chronic exposure to pharmaceuticals at low concentrations revealed significant alterations of metabolic and physiological endpoints.

Development and application of a sensitive feeding assay for daphnids based on the ingestion of fluorescent microparticles

“…37,38 Specically, acute and chronic exposure of Daphnia magna to metformin decreased the activity of various enzymes of the metabolism 25 and increased the activity of several detoxication enzymes, respectively. 39 The concentrations of pollutants tested in the developed feeding assay were notably lower compared to the effective concentrations reported in previous studies. This nding serves as compelling evidence for the high sensitivity of the method.…”

Acute and Transgenerational Effects of Non-Steroidal Anti-Inflammatory Drugs on Daphnia magna

“…Given the scarcity of research on the effects of indomethacin and ibuprofen on freshwater organisms, particularly D. magna, our study aimed to highlight their significance while also introducing additional markers of physiology other than mortality, growth, and reproduction rate as common endpoints. We recently demonstrated that markers related to physiology and enzymatic activity, in addition to metabolic perturbations, are useful endpoints for pollution assessment [28,30]. It is worth noting that this is the first reference of indomethacin, ibuprofen, and daphnids using additional molecular markers rather than using only toxicity results.…”

“…Daphnids were cultured under a 16 h:8 h of light:dark photoperiod at 20 • C in OECD media (final concentrations 0.29 g CaCl 2 •2H 2 O/L, 0.123 g MgSO 4 •7H 2 O/L, 0.065 g NaHCO 3 /L, 0.0058 g KCl/L, 2 µg Na 2 SeO 3 /L, pH 7.7) [28]. Indomethacin and ibuprofen were dissolved in DMSO, which had a final concentration of 0.005% v/v in the exposure, which is within the concentration range used in previous studies [27,29,30]. Neonates (<24 h) were collected from the third brood of their mothers and used for experiments.…”

“…To assess toxicity, 15 neonates were exposed to each NSAID separately, and their 1:1 mixture in a final volume of 50 mL OECD media with four replicates per concentration tested. Based on similar studies [21,28,[30][31][32][33][34], all assays were conducted with four (toxicity curves and biochemical assays) or five (feeding assay) replicates per condition tested. For toxicity, the OECD guidelines state that at least 40 animals (preferably in four groups of 10 animals should be used at each test concentration); however, in our study, we exceeded that number to 60 animals.…”

Combined Toxicity of Polystyrene Nanoplastics and Pyriproxyfen to Daphnia magna

“…This property is commonly employed in fixation, lethality, and reproductive tests [45,46]. D. magna has been used to study the short-or long-term effects of pollutants such as nanoparticles [47,48], pharmaceuticals [49], metals [50], and pesticides [51]. Moreover, studies on the effects of combined pollutants on D. magna have received wide attention [52,53].…”