Oil induced cardiac effects in embryonic sheepshead minnows, Cyprinodon variegatus.

Following the Deepwater Horizon oil spill in April 2010, much research has been conducted on the cardiotoxic effects of oil on fish. Sensitive life history stages, such as the embryonic period, have been targeted to elucidate the effects of polycyclic aromatic hydrocarbons (PAHs) on the developing cardiovascular systems of fish. However, much of this research has focused on rapidly developing pelagic species, with little emphasis on estuarine species with longer embryological periods. Moreover, previous studies have used heart rate as the primary endpoint to measure cardiac performance in embryos and larvae; an endpoint that on its own may overlook impairment in cardiac performance. This study aims to fill these knowledge gaps and provide a more holistic approach for assessing the effects of PAHs on cardiac function by exposing sheepshead minnow (Cyprinodon variegatus) embryos to two oil doses (150 and 300 µg/L tPAH nominally) throughout embryonic development and measuring cardiac responses through the identification of cardiotoxic phenotypes (pericardial edema) as well as calculation of cardiac output at 4 days post fertilization. Results of this study show significant increases in pericardial edema at both oil doses relative to controls as well as significantly reduced cardiac output - driven by reductions in ventricular stroke volume. This study is one of the first to assess cardiac output in embryonic fish exposed to oil and methods described here allow for more physiologically relevant measures of cardiac performance in early life stages through established and non-invasive measures.

The aqueous extract of Fridericia chica grown in northern Colombia ameliorates toxicity induced by Tergitol on Caenorhabditis elegans.

The aqueous extract of fallen leaves from Fridericia chica (Bonpl.) L.G. Lohmann is utilized as a remedy in communities at northern Colombia. Traditional uses include wound healing, gastrointestinal inflammation, leukemia and psoriasis, among others. The aims of this research were to evaluate the potential of the aqueous extract of fallen leaves of F. chica (AEFchica) to inhibit ethoxylated nonylphenol (Tergitol)-induced toxicity in Caenorhabditis elegans; and to identify its main components. The pharmacological properties of AEFchica was evaluated using a Tergitol-induced toxicity model in Caenorhabditis elegans. Lethality, locomotion, reproduction, and DAF-16 nuclear translocation were quantified. The chemical composition of AEFchica was carried out using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. AEFchica induced very little lethality on C. elegans (5.6%) even at high concentrations (10,000 µg/mL). The extract had no effect on locomotion impairing induced by ethoxylated nonylphenol. However, AEFchica (1000 µg/mL) abrogated Tergitol-induced mortality, recovering up to 53.3% of the nematodes from lethality induced by 10 mM Tergitol. Similarly, it also blocked Tergitol-dependent reproduction inhibition (82.1% recovery), as well as DAF-16 nuclear translocation (>95%), suggesting a prominent role on oxidative stress control. The chemical analysis indicated the presence of a great variety of molecules with known antioxidant, metabolic and immune modulator properties, such as hydroxylated methoxy flavones, N-methyl-1-deoxynojirimycin, and rehmaionoside A. In short, the aqueous extract of F. chica protects C. elegans from the deleterious effects of Tergitol on lethality, reproduction and oxidative stress involving DAF-16-mediated pathway. This extract is a promising source of bioactive phytochemicals for multi-target pharmacological purposes.

Effects of polycyclic aromatic hydrocarbons and abiotic stressors on Fundulus grandis cardiac transcriptomics.

Following the 2010 Deepwater Horizon oil spill, extensive research has been conducted on the toxicity of oil and polycyclic aromatic hydrocarbons (PAHs) in the aquatic environment. Many studies have identified the toxicological effects of PAHs in estuarine and marine fishes, however, only recently has work begun to identify the combinatorial effect of PAHs and abiotic environmental factors such as hypoxia, salinity, and temperature. This study aims to characterize the combined effects of abiotic stressors and PAH exposure on the cardiac transcriptomes of developing Fundulus grandis larvae. In this study, F. grandis larvae were exposed to varying environmental conditions (dissolved oxygen (DO) 2, 6 ppm; temperature 20, 30 °C; and salinity 3, 30 ppt) as well as to a single concentration of high energy water accommodated fraction (HEWAF) (∑PAHs 15 ppb). Whole larvae were sampled for RNA and transcriptional changes were quantified using RNA-Seq followed by qPCR for a set of target genes. Analysis revealed that exposure to oil and abiotic stressors impacts signaling pathways associated with cardiovascular function. Specifically, combined exposures appear to reduce development of the systemic vasculature as well as strongly impact the cardiac musculature through cardiomyocyte proliferation resulting in inhibited cardiac function and modulated blood pressure maintenance. Results of this study provide a holistic view of impacts of PAHs and common environmental stressors on the cardiac system in early life stage estuarine species. To our knowledge, this study is one of the first to simultaneously manipulate oil exposure with abiotic factors (DO, salinity, temperature) and the first to analyze cardiac transcriptional responses under these co-exposures.

Acute exposure to oil induces age and species-specific transcriptional responses in embryo-larval estuarine fish.

Because oil spills frequently occur in coastal regions that serve as spawning habitat, characterizing the effects of oil in estuarine fish carries both economic and environmental importance. There is a breadth of research investigating the effects of crude oil on fish, however few studies have addressed how transcriptional responses to oil change throughout development or how these responses might be conserved across taxa. To investigate these effects, we performed RNA-seq and pathway analysis following oil exposure 1) in a single estuarine species (Cyprinodon variegatus) at three developmental time points (embryos, yolk-sack larvae, free-feeding larvae), and 2) in two ecologically similar species (C. variegatus and Fundulus grandis), immediately post-hatch (yolk-sack stage). Our results indicate that C. variegatus embryos mount a diminished transcriptional response to oil compared to later stages, and that few transcriptional responses are conserved throughout development. Pathway analysis of larval C. variegatus revealed dysregulation of similar biological processes at later larval stages, including alteration of cholesterol biosynthesis pathways, cardiac development processes, and immune functions. Our cross-species comparison showed that F. grandis exhibited a reduced transcriptional response compared to C. variegatus. Pathway analysis revealed that the two species shared similar immune and cardiac responses, however pathways related to cholesterol biosynthesis exhibited a divergent response as they were activated in C. variegatus but inhibited in F. grandis. Our results suggest that examination of larval stages may provide a more sensitive estimate of oil-impacts than examination of embryos, and challenge assumptions that ecologically comparable species respond to oil similarly.

Parental exposure to Deepwater Horizon oil in different environmental scenarios alters development of sheepshead minnow (Cyprinodon variegatus) offspring.

The explosion of the Deepwater Horizon (DWH) oil exploration platform on April 20, 2010 began a catastrophic leak of approximately 640 million liters crude oil into the northern Gulf of Mexico (GOM), affecting more than 2100 km of coastline, including wetlands and estuaries that provide habitat and nursery for many aquatic species. Estuaries of the GOM are dynamic environments, with constant fluctuations in salinity and dissolved oxygen, including large hypoxic zones during summer months. Spawning fish in northern GOM estuaries following the DWH incident were at significant risk of oil exposure, and adverse environmental conditions at the time of exposure, such as hypoxia and low salinity, could have exacerbated developmental effects in the offspring. The present study investigated the effects of F0 parental oil exposure in different environmental scenarios on development of F1 sheepshead minnow (SHM) offspring. Adult SHM were exposed to the high-energy water accommodated fraction (HEWAF) of crude oil in three environmental scenarios: normoxic (NORM), hypoxic (HYP), and hypoxic with low salinity (HYP-LS). Parental HEWAF exposure in the NORM scenario resulted in developmental effects in F1 offspring, including altered heart rate, decreased length at hatch, and impaired prey capture. Co-exposure of F0 SHM to HEWAF and adverse environmental conditions altered HEWAF effects on F1 heart rate, hatch rate, prey capture, and survival. Time to hatch was not significantly impacted by parental HEWAF in any environmental scenario. The present study demonstrates that parental exposure to HEWAF results in developmental changes in F1 embryos, and co-exposure to adverse environmental conditions altered the effects for several developmental endpoints. These data suggest that SHM exposed to oil in estuaries experiencing hypoxia or low salinity may produce offspring with worsened outcomes. These developmental effects, in addition to previously reported reproductive effects in adult fish, could lead to long-term population level impacts for SHM.

Combined effects of salinity, temperature, hypoxia, and Deepwater Horizon oil on Fundulus grandis larvae.

Oil spills have polluted the marine environment for decades and continue to be a major source of polycyclic aromatic hydrocarbons (PAHs) to marine ecosystems around the globe, for example during the 2010 Deepwater Horizon spill. Although the toxicity of PAHs to fish has been well studied, their effects combined with abiotic stressors are poorly understood. The goal of this study was to describe the combined impacts of crude oil and environmental stressors on fish larvae, a sensitive life stage. Gulf killifish (Fundulus grandis) larvae (<24 h post-hatch) were exposed for 48 h to high energy water accommodated fractions (HEWAF; total PAHs 0-125 ppb) of Macondo oil from the Deepwater Horizon spill under different combinations of environmental conditions (dissolved oxygen 2, 6 ppm; temperature 20, 25, 30 °C; salinity 3, 10, 30 ppt). Even under optimal environmental conditions (25 °C, 10 ppt, 6 ppm) larval survival and development were negatively affected by PAHs, starting with the lowest concentration tested (∼15 ppb). Hypoxia and high temperature each increased the adverse effects of HEWAF on development and mortality. In contrast, salinity had little effect on any of the endpoints measured. Importantly, expression of the detoxifying gene cyp1a was highly induced in PAH-exposed larvae under normoxic conditions, but not under hypoxic conditions, potentially explaining the enhanced toxicity observed under hypoxia. This work highlights the importance of considering how suboptimal environmental conditions can exacerbate the effects of pollution on fish early life stages.

Transgenerational effects of polycyclic aromatic hydrocarbon exposure on sheepshead minnows (Cyprinodon variegatus).

The Deepwater Horizon oil spill resulted in the release of over 640 million L of crude oil into the Gulf of Mexico, affecting over 2000 km of shoreline, including estuaries that serve as important habitats and nurseries for aquatic species. Cyprinodon variegatus (sheepshead minnow) are small-bodied fish that inhabit northern Gulf of Mexico estuaries, are easily adaptable to laboratory conditions, and are commonly used in toxicological assessment studies. The purpose of the present study was to determine the somatic, reproductive, and developmental effects of an environmentally relevant polycyclic aromatic hydrocarbon (PAH) mixture, the oil high-energy water accommodated fraction (HEWAF), on experimentally exposed sheepshead minnow (F0 ) as well as 2 generations of offspring (F1 and F2 ) without additional exposure. The F0 generation exposed to HEWAF had increased liver somatic indices, altered egg production, and decreased fertilization. Several developmental endpoints in the F1 were altered by F0 HEWAF exposure. As adults, low HEWAF-exposed F1 females demonstrated decreased weight and length. Both the F1 and F2 generations derived from high HEWAF-exposed F0 had deficits in prey capture compared to control F1 and F2 , respectively. Correlations between endpoints and tissue PAHs provide evidence that the physiological effects observed were associated with hydrocarbon exposure. These data demonstrate that PAHs were capable of causing physiological changes in exposed adult sheepshead minnow and transgenerational effects in unexposed offspring, both of which could have population-level consequences. Environ Toxicol Chem 2019;38:638-649. © 2018 SETAC.

Combined effects of Deepwater Horizon crude oil and environmental stressors on Fundulus grandis embryos.

In the present study, we examined how sensitivity to oil changes in combination with environmental stressors in Fundulus grandis embryos. We exposed embryos (<24 h post fertilization) to a range of high-energy water accommodated fraction (HEWAF) concentrations (0-50 parts per billion [ppb] total polycyclic aromatic hydrocarbons [PAHs]) made from Macondo crude oil in conjunction with various environmental conditions (temperature: 20 and 30 °C; salinity: 3, 7, and 30 practical salinity units [PSU]; and dissolved oxygen: 2 and 6 mg/L). Endpoints included mortality, hatching rates, and expression of cytochrome p450 1a and 1c (cyp1a, cyp1c) in hatched larvae. There was 100% mortality for all fish under the 2 parts per million (ppm) dissolved oxygen regimes. For the 6 mg/L dissolved oxygen treatments, mortality and median lethal time (LT50) were generally higher in the 30 °C treatments versus the 20 °C treatments. Oil increased mortality in fish exposed to the highest concentration in the 20-3-6 (°C-PSU-mg/L), 25-7-6, and 30-30-6 conditions. Hatching was driven by environmental conditions, with oil exposure having a significant impact on hatching in only the 25-7-6 and 30-30-6 groups at the greatest HEWAF exposure. Expression of cyp1a was up-regulated in most treatment groups versus the controls, with cyp1c expression exhibiting a similar pattern. These data suggest interactive effects among temperature, salinity, and PAHs, highlighting a need to further assess the effects of oil exposure under various environmental conditions. Environ Toxicol Chem 2018;37:1916-1925. © 2018 SETAC.

Blood chemistry values for shovelnose and lake sturgeon.

Blood chemistry panels are commonly used for assessing the general health of vertebrate animals. Here, we present novel blood chemistry data for two North American sturgeon species, shovelnose sturgeon Scaphirhynchus platorynchus and lake sturgeon Acipenser fulvescens. Measurements were done using a portable chemistry analyzer (VetScan Analyzer; Abaxis). Among the plasma values measured (mean ± SD for shovelnose and lake sturgeon, respectively) were total proteins (3.7 ± 0.9 and 2.8 ± 0.4 g/dL), albumin (2.0 ± 0.5 and 1.1 ± 0.2 g/dL), globulin (1.7 ± 0.7 and 1.7 ± 0.3 g/dL), glucose (107 ± 46 and 62 ± 9.7 mg/dL), sodium (Na(+); 132 ± 3.6 and 150 ± 14 mEq/L), potassium (K(+); 3.5 ± 0.2 and 2.8 ± 1.7 mEq/L), phosphorus (10.4 ± 1.9 and 11.6 ± 3.6 mg/dL), and aspartate aminotransferase (AST; 676 ± 433 and 634 ± 234 IU/L). Higher values for total proteins, albumin, glucose, and Na(+) in shovelnose sturgeon than in lake sturgeon probably are the result of handling stress. In addition, the plasma of male shovelnose sturgeon had higher concentrations of AST, glucose, and globulin than did that of females, whereas the plasma of females had higher concentrations of albumin and K(+) than that of males. This study is the first to report blood chemistry data for shovelnose sturgeon. Robust blood chemistry databases can be used by aquaculturists and fish managers for monitoring sturgeon health.

Expression signatures for a model androgen and antiandrogen in the fathead minnow (Pimephales promelas) ovary.

Trenbolone, an anabolic androgen, and flutamide, an antiandrogen, are prototypical model compounds for agonism and antagonism of the androgen receptor. We hypothesized that 48 h exposures of female fathead minnows (Pimephales promelas) to environmentally relevant concentrations of these chemicals would alter genes regulated by the androgen receptor and that a mixture of the two compounds would block the effects. Gene expression in the ovaries was analyzed using a fathead minnow-specific 22,000-gene microarray. Flutamide altered abouttwicethe number of genes astrenbolone, most of which appeared to be through pathways not associated with the androgen receptor. A group of 70 genes, of which we could identify 37, were reciprocally regulated by trenbolone and flutamide. These are candidates for specific biomarkers for androgen receptor mediated gene expression. Four genes stand out as specifically related to reproduction: sperm associated antigen 8 (SPAG8), CASP8 and FADD-like apoptosis regulator (CFLAR), corticotropin releasing hormone (CRH), and 3beta-hydroxysteroid dehydrogenases (3beta-HSD). Three notable transcriptional regulators including myelocytomatosis viral oncogene homologue (MYC), Yin Yang 1 (YY1), and interferon regulator factor 1 (IRF1) may function as early molecular switches to control phenotypic changes in ovary tissue architecture and function in response to androgen or antiandrogen exposure.