Toxic responses of medaka, D‐rR strain, to polychlorinatednaphthalene mixtures after embryonic exposure by in ovo nanoinjection: A partial life‐cycle assessment

Abstract

Polychlorinated naphthalenes (PCNs) are organic compounds with some chemical properties and uses similar to polychlo‐rinated biphenyls. Polychlorinated naphthalenes have been detected in biota from certain aquatic environments. The toxicities of several PCN technical mixtures (Halowax) to medaka (Oryzias latipes) were determined by use of an embryo nanoinjection method. Medaka eggs (early gastrula) were injected with 0.5 nl of triolein (vehicle control) or 0.5 nl of four to five graded doses (0.3–30 ng/egg) of Halowax 1014, Halowax 1013, or Halowax 1051 in triolein. Following exposure, embryos developed, and fry were reared to sexual maturity (4 months), at which time they were euthanized. Responses were evaluated as early life stage (ELS) and early adult life stage (EALS) assessments. For ELS, lethality and sublethal alterations in embryos and larvae (<16 d old), such as craniofacial, cardiovascular, and myoskeletal deformities and abnormal or delayed hatch, were monitored for the first 9 d, and a dose severity index was computed. The EALS assessment examined the survival of 16‐d‐old larvae until early adulthood (123 ± 3 d old), including gonadosomatic index (GSI) and morphometry. Halowax 1014 was found to be the most toxic mixture (LD50 4.2 ng/egg), whereas Halowax 1013 and 1051 were significantly less toxic (LD50s could not be determined). The gonadosomatic index of females was significantly less in fish dosed with Halowax 1014 or 1051. The LD50 for medaka embryos nanoinjected with 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) is about 0.75 pg/egg. Thus, Halowax 1014 was 5,585‐fold less potent than TCDD. For Halowax 1014, ELS assessments accurately predicted the results of EALS assessments.

Relative Potencies of Individual Polychlorinated Naphthalenes and Halowax Mixtures To Induce Ah Receptor-Mediated Responses

“…For example, Engwall et al (17) observed EROD induction and lethality in chicken embryos with exposure to a mixture of 1,2,3,4,6,7/1,2,3,5,6,7-hexa-CNs 66 and 67 (ED 50 for EROD induction ) 0.06 mg/kg of egg), but when they tested 1,2,3,4,5,6,7-hepta-CN (PCN 73), they observed less EROD induction (the greatest dose, 3 mg/kg, caused only 50% of the maximal induction caused by the hexa-CN mix). Similarly, REPs of Halowax mixtures determined in H4IIE-luc cells (Halowax 1051 > 1014 > 1013) were different from REPs determined in medaka fish (Halowax 1014 > 1013 > 1051) (48). Interestingly, the relative rank order potency of CYPIA expression in rainbow trout sac fry is consistent with our results with the order being 66/67 > 73 > Halowax 1014 (21).…”

Biotoxicity evaluation of coking wastewater treated with different technologies using Japanese medaka (Oryzias latipes)

“…This is also the time for the formation of livers in the embryos. 25 For Fenton and electro-Fenton effluents, the number of embryo lesions was signicantly higher than that in the controls and MBR effluent (p < 0.05) (Table 3). No embryo could be hatched in MBR-F and MBR-EF effluents of dilutions more than 25%.…”

Retene, pyrene and phenanthrene cause distinct molecular-level changes in the cardiac tissue of rainbow trout (Oncorhynchus mykiss) larvae, part 1 – Transcriptomics

“…At sampling day, three random larvae per tank (N = 36 per treatment, 24 for the 14 days exposure) were photographed for morphometric analyses: larvae length and yolk sac area were measured later using the ImageJ software (Rueden et al, 2017). All larvae were monitored for signs of BSD (pericardial and yolk sac edemas, hemorrhages, craniofacial and spinal deformities) and a severity index ranging from 0 to 1 was calculated for each tank according to the scoring scheme of Villalobos et al (2000) with the modifications from Scott and Hodson (2008). Larvae were then quickly and carefully dissected under the microscope: the heart of each larva was separated from the rest of the body using fine forceps (Dumont #5, Fine Science Tools, Heidelberg, Germany).…”