Itzick Vatnick

Atrazine is an immune disruptor in adult northern leopard frogs (Rana pipiens)

Atrazine, the most widely used herbicide in the United States, has been shown in several studies to be an endocrine disruptor in adult frogs. Results from this study indicate that atrazine also functions as an immune disruptor in frogs. Exposure to atrazine (21 ppb for 8 d) affects the innate immune response of adult Rana pipiens in similar ways to acid exposure (pH 5.5), as we have previously shown. Atrazine exposure suppressed the thioglycollate-stimulated recruitment of white blood cells to the peritoneal cavity to background (Ringer exposed) levels and also decreased the phagocytic activity of these cells. Unlike acid exposure, atrazine exposure did not cause mortality. Our results, from a dose-response study, indicate that atrazine acts as an immune disruptor at the same effective doses that it disrupts the endocrine system.

Effects of Glyphosate and Polyoxyethylenamine on Growth and Energetic Reserves in the Freshwater Crayfish Cherax quadricarinatus (Decapoda, Parastacidae)

Freshwater crayfish Cherax quadricarinatus have a high commercial value and are cultured in farms where they are potentially exposed to pesticides. Therefore, we examined the sublethal effects of a 50-day exposure to glyphosate acid and polyoxyethylenamine (POEA), both alone and in a 3:1 mixture, on the growth and energetic reserves in muscle, hepatopancreas and hemolymph of growing juvenile crayfish. Exposure to two different glyphosate and POEA mixtures caused lower somatic growth and decreased muscle protein levels. These effects, caused by both compounds interacting in the mixture, could also be synergistic because they were expressed even at the lowest concentration. The decrease in protein levels could be related to the greater use of other energy reserves. This hypothesis is supported by the decrease in muscle glycogen stores due to glyphosate exposure and the decrease in lipid reserves associated with exposure to POEA.

Acid exposure is an immune disruptor in adult Rana pipiens

Acidic environments are physiological stressors for amphibians. The objective of the present study was to document the effect of an acidic environment on innate immune system function under controlled experimental conditions in Rana pipiens. We developed an in vivo assay, by injecting a suspension of 1-microm fluorescent beads in fluid thioglycollate, to induce peritonitis. The number of peritoneal exudate leukocytes and their phagocytic activity did not increase with thioglycollate injection when frogs were exposed to pH 5.5 compared to when frogs were exposed to pH 7.0. An environment of pH 5.5 disrupted the inflammatory response of frogs compared to an environment of pH 7.0; at pH 5.5, more nonphagocytic leukocytes and fewer highly phagocytic leukocytes were found compared to those in frogs exposed to pH 7.0. Frogs stimulated by thioglycollate injection and exposed to pH 5.5 had a 50% increase in cells that did not exhibit phagocytosis and a 4- to 10-fold reduction in the number of highly phagocytic cells. This is evidence that acid exposure functions as an immune disruptor in adult R. pipiens under laboratory conditions.

Effects of acid exposure on natural resistance and mortality of adult Rana pipiens

Acid is a prevalent environmental stressor for North American frogs, and in the last few decades, many aquatic environments have become increasingly acidic (Freda, 1986). The effects of acid exposure on developing frogs have been demonstrated. Acidic pH may decrease sperm motility in Rana pipiens (Schlichter, 1981) and cause high mortality and developmental abnormalities in embryos and tadpoles (Schlichter, 1981; McDonald et al., 1984; Pierce, 1984, 1985; Freda and Dunson, 1985; Bradford et al., 1992). However, lethal effects of low pH on adult frogs are poorly understood. A few studies demonstrated acidic conditions disrupt transport of ions in isolated skin in vitro (Ferreira and Hill, 1982; Lyall et al., 1992; Feder et al., 1993), which at pH below 4–5 may cause death (Boutilier et al., 1992). The relation of stress to immunosuppression is well documented in many vertebrates (Blecha and Kelley, 1981; Regnier and Kelley, 1981; Blecha et al., 1982; Marnila et al., 1995). In addition, amphibians exposed to low pH may experience immunosuppression followed by microbial disease resulting in mortality (Carey, 1993). We previously demonstrated that adult Rana pipiens exposed to pH 5.5 for 10 days experienced high mortality rates (Vatnick et al., 1999). Here, we characterize effects of acid exposure on defense systems of adult R. pipiens. Fifty frogs were purchased from Charles D. Sullivan Co. Inc. (Nashville, TN) and arrived via airmail. These were wild R. pipiens from ponds in the northeastern United States captured by licensed collectors. In our lab, frogs were housed in individual plastic containers with 800–1000 ml of aged tap water (conductance 5 0.366 mohs, Na1 5 0.14 mM , K1 5 0.3 mM, Mg11 5 0.30 mM, and Ca11 5 0.24 mM) and were acclimated at room temperature for at least two days after arrival and prior to the start of any experiment. During experiments, frogs were placed in individual autoclaved containers containing sterilized citrate buffer. Buffers were prepared in 75-liter carboys, using tap water, and each buffer was autoclaved for 1 h. The pH 5.5 buffer was prepared by adding 4.8 mM citric acid anhydride, 9.5 mM sodium hydroxide, and 0.6 mM sodium citrate to 75 liters of tap water. The pH 7.0 buffer was prepared by adding 2.4 mM citric acid anhydride, 4.8

The Influence of Ambient Temperature and the Energy and Protein Content of Food on Nitrogenous Excretion in the Egyptian Fruit Bat (Rousettus aegyptiacus)

The diets of frugivorous and nectarivorous vertebrates contain much water and generally have high energy but low protein contents. Therefore, we tested the prediction that to save energy under conditions of high energy demands and high water intake, frugivorous Egyptian fruit bats (Rousettus aegyptiacus) will increase both the absolute quantity and the proportion of ammonia in their urine. We also examined whether such changes occur when protein intake is low and water intake is high. We did three feeding trials. In trials 1 and 2, bats were fed one of four liquid diets containing constant soy protein concentrations but varying in sucrose concentration and were kept at ambient temperatures (Ta) of 30°C and 12°C, respectively. In trial 3, bats were kept at \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

Effects of atrazine on vitellogenesis, steroid levels and lipid peroxidation, in female red swamp crayfish Procambarus clarkii

T_{\mathrm{a}\,}=12^{\circ }\mathrm{C}\,

Growth and metabolism of the placenta after unilateral fetectomy in twin pregnant ewes.

\end{document} and fed one of four liquid diets with equal sucrose concentrations but varying protein concentrations. In trial 1, food intake at a sucrose concentration of 256 mmol/kg H2O was initially high but decreased to a constant rate with further increases in sucrose concentration, while in trial 2, food intake decreased exponentially with increasing sucrose concentration. As predicted, at 12°C with varying sucrose concentration, both the absolute quantity and the fraction of ammonia in the bats’ urine increased significantly with food intake ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape