Abstract:
This dataset contains measurements of mahi-mahi (Coryphaena hippurus) whole animal performance using swim tunnel respirometry and include maximal sustained swimming speed, minimum metabolic rate, maximum metabolic rate, and aerobic scope following exposure to control seawater or seawater containing fracking fluid (0.75 or 2.75%). Fracking fluid contains polycyclic aromatic hydrocarbons (PAHs). Mahi heart cells were exposed to control saline or saline containing a dilution of fracking fluid (1 or 2%). Following exposure, various measures of cellular function were assessed including: sarcomere shortening, departure and return shortening velocity and time to peak shortening.
Suggested Citation:
Folkerts, E., Heuer, R., Grosell, M.. 2020. Effects of fracking fluid (containing polycyclic aromatic hydrocarbons) on cell function and swim performance in mahi-mahi (Coryphaena hippurus). Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-dhw9-d519
Data Parameters and Units:
The dataset consists of 7 Excel files whose titles describe the data therein.
Cardiomyocyte Contractile Properties: - Relative sarcomere contraction size (baseline Percent Peak Height; bl % Peak Height). Units: percent compared to control conditions. - Relative sarcomere contraction speed (d/dt). Units: percent compared to control conditions. - Relative times to peak sarcomere peak contraction 50, 75, and 90% (t to Peak 50, 75, and 90%). Units: percent compared to control conditions. - Relative sarcomere relaxation speed (-d/dt). Units: percent compared to control conditions. - Relative times to relaxed, baseline sarcomere states 50, 75, and 90% (t to bl 50, 75, and 90%). Units: percent compared to control conditions. - Relative trace exponential decay constant (tau). Units: percent compared to control conditions.
Mahi Swimming Performance and Respirometry: - Swimming performance (Ucrit). Units: body lengths per second (BL/s). - Aerobic scope (AS), standard metabolic rate (SMR), and maximum metabolic rate (MMR). Units: milligrams oxygen per kilogram per hour (mg O2 kg-1 hr-1).
Mahi Ventricle Gene Expression: Real-time quantitative polymerase chain reaction gene analysis (analyzed via delta CT protocols). Units: relative fold change.
Mahi Plasma Osmolarity: Plasma osmolarity. Units: milliosmoles (mOsm).
Mahi Biometrics: Mahi body mass and heart mass. Units: grams (g). - Mahi fork length. Units: centimeters (cm).
Cell Exposure Water Parameters: - Raw, filtered hydraulic fracturing-generated flow back water (HF-FW) polycyclic aromatic hydrocarbon (PAH) analysis. Units: micrograms per litre (ug/L). - Raw, filtered hydraulic fracturing-generated flow back water (HF-FW) inorganic analyte characterization. Units: milligram per litre (mg/L) and micromolar (mM). - Cell exposure solution osmolarities. Units: milliosmoles (mOsm).
Whole Organism Exposure Water Parameters: - Temperature. Units: degrees Celsius (°C). - pH. Units: N/A. - Dissolved oxygen (D.O.). Units: milligrams per liter (mg/L). - Salinity. Units: parts per thousand (PPT). - Ammonia. Units: micromolar.
Methods:
Organisms and Exposure Preparation: Juvenile mahi-mahi obtained from broodstock at the University of Miami experimental hatchery. For whole organism exposures, fish were exposed to control (filtered seawater), 0.75% HF-FW, 2.75% HF-FW, or a salt control (a solution containing the same concentration of major cations and anions as the 2.75% HF-FW solution). Exposures to treatments were for 24 hrs. Temperature, salinity, dissolved oxygen, and ammonia were monitored. For cell exposures, the HF-FW had to be first vacuum filtered through a two-stacked 90m mm, 0.3 um glass fiber filter to eliminate debris from potentially interfering with the cell imaging software. Cells were exposed to either 1% or 2% of this filtered HF-FW, control (physiological mahi saline solution), salt control (as mentioned previously, a solution matching the major cations and anions of the 2% filtered HF-FW), or an osmotic control (a solution matching the osmotic pressure of the 2% HF-FW; achieved by dissolving appropriate amounts of mannitol to physiological saline solution).
Cardiomyocyte Contractile Properties: Isolated mahi cardiomyocyte contractile properties were investigated using a real-time IonOptix Myocyte Contractility system (IonOptix, MA, USA) paired with an electrode outfitted perfusion chamber and a MyoCam-S camera. SarcLens technology within the IonWizard software (v6.0) was used to analyze many properties of sarcomere shortening (an index of overall cell contractility), including overall sarcomere contraction size, contraction/relaxation velocities, time to peak contraction (50%, 70%, and 90%), time to relax, baseline states (50%, 70%, and 90%), and relaxation trace exponential decay constant, tau (a kinetic measurement of sarcomere relaxation). - All cells analyzed were put through a force-frequency (FF) protocol, where following basal stimulation set up (0.5 Hz), stimulation frequency following solutions switches to aforementioned treatments gradually increased to cover a frequency of observed heart rates of in situ mahi heart preparations (1.5, 2.0, 2.5, and 3.0 Hz). A constant voltage of 6 mV was used during experiments. All contractile indices were compared against the control, baseline conditions of that same cell.
Mahi Swimming Performance and Respirometry: Following 24 hr exposures to treatments, mahi were transferred to and acclimated in 5-L Brett-type swim tunnel respirometers outfitted with a fiber-optic oxygen probe connected to a Witrox Fibox oxygen meter (PreSens Precision Sensing, GER) and AutoResp 2.1.0 software (Loligo Systems, DEN) for intermittent flow respirometry. Fish were acclimated for 16 hrs overnight and then swam through a swim-step protocol to determine critical swim speed (Ucrit) and aerobic scope. Briefly, this swim-step protocol consisted of swimming fish for 20-minute intervals which were increased by water velocity increments of 0.5 BL/s. A scaled, standardized approach was used to estimate aerobic scope for these organisms.
Ventricle Gene Expression: Following 24 hr, whole organism exposures to treatments, one fish not used for swimming and respirometry analyses was sacrificed and harvested for tissues. Total RNA was extracted from excised mahi ventricles using TRIzol according to manufacturer’s protcols (Ambion Life Technologies, USA) and complementary DNA synthesis performed using SuperScript III Reverse Transcriptase (Invitrogen, USA) with a mix of oligo(dT) and hexamer primers. - Quantitative real-time PCR (qPCR) was performed in 96-well plates using an ABI 7500 Real-Time PCR system (Applied Biosystems, USA). Transcript expression changes were determined by delta CT analysis using ribosomal protein S25 as an endogenous control.
Mahi Plasma and Cell Exposure Osmolarity: Mahi plasma and cardiomyocyte solution osmolarities were determined by running samples on a vapor pressure osmometer (Vapro 5520, Wescor Inc., FRA).
HF-FW Inorganic and Organic Chemical Characterization: Raw HF-FW inorganic characterization was performed via inductively coupled plasma (ICP)- MS/MS using an Agilent 8800 Triple Quadrupole ICP-MS. - Raw and diluted HF-FW organic characteristics were performed by ALS Environmental (Kelso, WA, USA) using Gas chromatography-mass spectrometry (GC-MS) with selective ion monitoring based on USEPA method 8270D.
Statistical Analyses: All data were tested for normality and homogeneity of variance by Shapiro-Wilk and Levene’s tests, respectively. For cardiomyocyte contractile analyses, values were assessed using a two-way repeated measures ANOVA. For all other analyses, one-way ANOVAs were performed. Following ANOVA analyses, Holm-Sidak posthoc multiple comparisons were performed to determine the significance between treatment conditions.
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