Feeding Ration Impacts Larval Pimephales Promelas 7-Day Subchronic Growth Endpoint: Case Study with Perfluorooctanesulfonic Acid.

The larval fathead minnow, Pimephales promelas, 7-day subchronic survival and growth standard toxicity test method is commonly used for research and regulatory testing of effluents and compounds, including emerging contaminants such as Perfluorooctanesulfonic Acid (PFOS). Existing feeding guidelines for testing are described in multiple methods but are open to interpretation. The current study sought to determine the impact of feeding ration on P.

Acute Toxicity of Eight Aqueous Film-Forming Foams to 14 Aquatic Species.

Researchers have developed numerous per- and polyfluoroalkyl substances (PFAS)-free aqueous film-forming foam (AFFF) formulations to replace PFAS-containing AFFF used for fire suppression. As part of the Department of Defense's Strategic Environmental Research and Development Program (SERDP), we examined the direct lethal effects of seven PFAS-free AFFF and a PFAS-containing AFFF on 14 aquatic species using a series of lethal concentration (LC50) tests. We assessed the LC10, LC50, and LC90 values using log-logistic and logit analyses.

Sensitivity of the Marine Calanoid Copepod Pseudodiaptomus pelagicus to Copper, Phenanthrene, and Ammonia.

There are limited acute toxicity test methods for native North American marine species that are considered zooplankton for their entire life cycle. Examples of standardized marine zooplankton methods include mussel, bivalve, and echinoderm development tests that use a relatively short-lived planktonic larval stage, chronic life-cycle toxicity tests using epibenthic copepods, and a 24-h Acartia tonsa copepod test method. The objectives of the present study were to: 1) develop and evaluate a novel, 48-h acute toxicity test method using the marine North American copepod Pseudodiaptomus pelagicus that is planktonic for its entire life cycle, and 2) determine the sensitivity of P.

Estrogen protects cardiac myogenic (H9c2) rat cells against lethal heat shock-induced cell injury: modulation of estrogen receptor alpha, glucocorticoid receptors, heat shock protein 70, and iNOS.

In the present study we have established that exposure of rat cardiac myoblasts (H9c2 cells) to 46 degrees C for 1 hour (lethal heat shock) resulted in optimal cell injury as determined by lactate dehydrogenase release. Pretreatment of H9c2 cells for 24 hours with 17beta-estradiol significantly protects myoblasts against subsequent lethal heat shock exposure in a concentration-dependent manner with maximum protection obtained at 1 microM of 17beta-estradiol. With Western blotting, it was observed that 17beta-estradiol-protected cells had significantly higher levels of the estrogen receptor alpha and inducible heat shock protein 70 (hsp70) as well as inducible nitric oxide synthase (iNOS) levels compared with lethal heat shock-exposed cells.

The suppression of testis-brain RNA binding protein and kinesin heavy chain disrupts mRNA sorting in dendrites.

Ribonucleoprotein particles (RNPs) are thought to be key players in somato-dendritic sorting of mRNAs in CNS neurons and are implicated in activity-directed neuronal remodeling. Here, we use reporter constructs and gel mobility shift assays to show that the testis brain RNA-binding protein (TB-RBP) associates with mRNPs in a sequence (Y element) dependent manner. Using antisense oligonucleotides (anti-ODN), we demonstrate that blocking the TB-RBP Y element binding site disrupts and mis-localizes mRNPs containing (alpha)-calmodulin dependent kinase II (alpha)-CAMKII) and ligatin mRNAs.

Fractals for multicyclic synthesis conditions of biopolymers. Examples of oligonucleotide synthesis measured by high-performance capillary electrophoresis and ion-exchange high-performance liquid chromatography.

We have developed models of patterns for nucleotide chain growth. These patterns are measurable by high-performance capillary electrophoresis and ion-exchange high-performance liquid chromatography in crude products of solid-phase synthesized 30mer and 65mer oligodeoxyribonucleotide target sequences N. We introduce mathematical methods for finding characteristic values d(o) and p(o) for constant chemical modes of growth as well as d and p for non-constant chemical modes of growth (d = probability of propagation, p = probability of termination).

pH modulates cAMP-induced increase in Na+ transport across frog skin epithelium.

Apical membrane potential (Va), fractional apical membrane resistance (FRa), and/or intracellular pH (pHi) were measured in principal cells of isolated frog (Rana pipiens) skin with microelectrodes under short-circuit conditions. Apical exposure to 0.33 mM 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate (cAMP) depolarized Va, decreased FRa and increased short-circuit current (Isc).

Regulation of apical Na+ conductive transport in epithelia by pH.

Alterations in extracellular (pHo) and/or intracellular pH (pHi) have significant effects on the apical Na+ conductive transport in tight epithelia. They influence apical membrane Na+ conductance via a direct effect on amiloride-sensitive apical Na+ channel activity and indirectly through effects on the basolateral Na+/K(+)-ATPase. Changes in pH also modulate the hormonal regulation of apical Na+ conductive transport.

Na+ transport and pH in principal cells of frog skin: effect of antidiuretic hormone.

Intracellular pH (pHi), apical membrane potential (Va), and fractional apical membrane resistance (FRa) were measured in principal cells of isolated frog skin (Rana pipiens) with double-barreled microelectrodes under short-circuit conditions. Basolateral exposure to 10 mU/ml arginine vasotocin (AVT) depolarized Va by 30 mV, decreased FRa by 33%, increased short-circuit current (Isc) by 17 microA, and increased pHi by 0.17 pH units.

Potential-induced changes in intracellular pH.

In a variety of cell types and tissues there is a strong dependence of intracellular pH (pHi) on membrane potential (Vm). Since cell Vm values can be altered by hormones, ion concentrations, and changes in membrane conductances, the potential-dependent changes in pHi may serve as an important mechanism by which cells can alter their pHi to an environmental stimulus. The H+ flux across the cell membranes is thought to take place via putative H+ channels that are blocked by low concentrations of divalent metal ions.

Na+ channel blockers inhibit voltage-dependent intracellular pH changes in principal cells of frog (Rana pipiens) skin.

1. The relationship between Va and pHi was studied with double-barrelled microelectrodes in principal cells of frog skin (Rana pipiens) when (i) the transepithelial potential (Vt) was clamped at different values of Vt and (ii) when the pH of the apical solution was altered. 2.

Effect of changes in extracellular potassium on intracellular pH in principal cells of frog skin.

Intracellular pH (pHi), apical membrane potential (Va), and fractional apical membrane resistance (FRa) were measured in principal cells of isolated frog skin (Rana pipiens) with double-barreled microelectrodes under short-circuit and open-circuit conditions. Basolateral exposure to high K+ concentration or Ba2+ depolarized V(a), decreased short-circuit current, and increased FRa and pHi. However, an increase in K+ subsequent to Ba2+ application did not induce additional changes in these parameters.

A modified technique for the measurement of sulfhydryl groups oxidized by reactive oxygen intermediates.

This paper suggests a simple modification of the Ellman procedure when used to measure accurate changes in sulfhydryl (-SH) content induced by reactive oxygen intermediates (ROI). This modification became necessary when we found that the standard technique did not produce time invariant results in the presence of ROI-generating systems. Cysteine (cys; 20-100 microM) in 20 mM imidazole buffer (pH 7.

pH in principal cells of frog skin (Rana pipiens): dependence on extracellular Na+.

Measurements of intracellular pH (pHi) and of apical cell membrane potential (Va) were made in principal cells of frog skin (Rana pipiens) with double-barrel microelectrodes under open-circuit conditions. The tissues were pretreated with stilbenes (10(-3) M) and bathed in HCO3- -free NaCl Ringer solution that was buffered with 6 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (pH 7.8).

pH in principal cells of frog skin (Rana pipiens): effects of amiloride and potential.

Intracellular pH (pHi) and apical cell membrane potential (Va) were determined in principal cells of frog skin (Rana pipiens) with double-barrel micro-electrodes. In the Northern and Southern varieties, respectively, pHi is 0.38 and 0.

Effect of changes in extracellular Cl on intracellular Cl activity in frog skin.

Intracellular Cl activity was measured in isolated frog skin (Rana pipiens) with double-barrel microelectrodes. The initial rate of Cl uptake was measured in Cl-depleted cells on reexposure to Cl on apical or basolateral side. In skins with high and low conductance, cell CL activity increased 1.

Potential dependence of unidirectional chloride fluxes across isolated frog skin.

Isolated frog skins were voltage clamped at transepithelial potentials (Vt) ranging from -60 mV to 60 mV to measure transepithelial 36Cl- fluxes from the apical to the basolateral bathing solution (J13) and in the opposite direction (J31). The potential dependence of fluxes obtained in Na+-free choline Ringer's indicates the presence of conductive and nonconductive components that probably correspond to fluxes through paracellular and cellular pathways, respectively. Rectification of fluxes with reversal of the potential reflects a structural asymmetry, presumably in surface charge density.

Intracellular Cl activity changes of frog skin.

The intracellular Cl activity and potential were determined in short-circuited frog skin with single-barrel microelectrodes. With NaCl Ringer solution on the apical and basolateral side, the intracellular Cl activity was 15.5 +/- 0.

Active transport and exchange diffusion of Cl across the isolated skin of Rana pipiens.

Transepithelial Cl influx and efflux were measured in pairs of frog skin (Rana pipiens) matched according to short-circuit current, tissue conductance, and transepithelial potential (TEP). The skins were bathed symmetrically in NaCl Ringer and voltage clamped at TEP values ranging from -60 to +60 mV. At 0 TEP, Cl influx and net inward Cl movement (in neq X h-1 X cm-2) were, respectively, 961 +/- 116 and 463 +/- 68 in NaCl Ringer, 509 +/- 52 and 202 +/- 53 in amiloride-treated skins, 4,168 +/- 777 and 1,444 +/- 447 in theophylline-treated skins, and 587 +/- 38 and 97 +/- 44 in Na-free Ringer.

The identity of the current carriers in canine lingual epithelium in vitro.

Ion transport across the lingual epithelium has been implicated as an early event in gustatory transduction. The fluxes of isotopically labelled Na+ and Cl- were measured across isolated canine dorsal lingual epithelium under short-circuit conditions. The epithelium actively absorbs Na+ and to a lesser extent actively secretes Cl-.

Insulin decreases apical cell membrane resistance in cultured kidney cells (A6).

Intracellular potentials measured across the apical and basolateral cell membranes of cultured renal A6 cells were -53.5 +/- 1.5 and -48.

Insulin stimulation of Na+ transport and glucose metabolism in cultured kidney cells.

A line of toad kidney cells (A6) in continuous culture was evaluated for ion transport and metabolic responses to insulin. The cells were grown on permeable supports to allow access of the medium to both basolateral and apical sides of the epithelium. Insulin, on the basolateral side only, produced an increase in short-circuit current (Isc) that was maximal at 40-60 min.

Influence of extracellular Cl concentration on Cl transport across isolated skin or Rana pipiens.

The effect of changes in Cl concentration in the external and/or serosal bath on Cl transport across short-circuited frog skin was studied by measurements of transepithelial Cl influx (J13Cl) and efflux (J31Cl), short-circuit current, transepithelial potential, and conductance (Gm). J14Cl as well as J31Cl were found to have a saturating component and a component which is apparently linear with Cl concentration. The linear component of J31Cl appears only upon addition of Cl to external medium, and about 3/4 of this component does not contribute to Gm.