Northern Leopard Frogs Rana Pipiens Research Articles

Effect of e-liquid from an electronic cigarette on the immune profile ofRana pipiens

Little is known about the effect of electronic cigarette usage, although the number of people using the devices continues to increase. Here we examine the effect of e-liquid with different concentration levels of nicotine from an electronic cigarette on the immune profile of the northern leopard frog Rana pipiens. Using a Sigelei Mini 30W electronic cigarette, frogs were exposed to vapor for 10 minutes, 6 days a week, for 3 weeks. We hypothesized that e-liquid vapor would alter the leukocyte differentials and positively correlate with the nicotine concentration. Our results indicate mean lymphocyte percent decreased with both vapor exposures without nicotine (24.8 ± 0.0% in control vs. 6.0 ± 1.2%) and with nicotine (24.8 ± 0.0% in control vs. 5.8 ± 4.0%), whereas the mean neutrophil percent increased with vapor without nicotine (60.8 ± 0.0% in control vs. 89.4 ± 3.0%) and with nicotine (60.8 ± 0.0% in control vs. 90.3 ± 6.0%). There was a significant positive correlation between vapor exposure and total neutrophil differentials (r = 0.954, p 0.05). Monocyte, basophil, and eosinophil percentages also decreased in frogs that were exposed to vapor. These findings suggest that electronic cigarette smoke alters the immune profile of frogs with or without nicotine.

Agrochemicals increase trematode infections in a declining amphibian species

Global amphibian declines have often been attributed to disease, but ignorance of the relative importance and mode of action of potential drivers of infection has made it difficult to develop effective remediation. In a field study, here we show that the widely used herbicide, atrazine, was the best predictor (out of more than 240 plausible candidates) of the abundance of larval trematodes (parasitic flatworms) in the declining northern leopard frog Rana pipiens. The effects of atrazine were consistent across trematode taxa. The combination of atrazine and phosphate--principal agrochemicals in global corn and sorghum production--accounted for 74% of the variation in the abundance of these often debilitating larval trematodes (atrazine alone accounted for 51%). Analysis of field data supported a causal mechanism whereby both agrochemicals increase exposure and susceptibility to larval trematodes by augmenting snail intermediate hosts and suppressing amphibian immunity. A mesocosm experiment demonstrated that, relative to control tanks, atrazine tanks had immunosuppressed tadpoles, had significantly more attached algae and snails, and had tadpoles with elevated trematode loads, further supporting a causal relationship between atrazine and elevated trematode infections in amphibians. These results raise concerns about the role of atrazine and phosphate in amphibian declines, and illustrate the value of quantifying the relative importance of several possible drivers of disease risk while determining the mechanisms by which they facilitate disease emergence.

Kinetics and potency of halothane, isoflurane, and desflurane in the Northern Leopard frog Rana pipiens

Equilibration between delivered and effect site anesthetic partial pressure is slow in frogs. The use of less soluble agents or overpressure delivery may speed equilibration. Ten Northern leopard frogs were exposed to 3-4 constant concentrations of halothane, isoflurane or desflurane and their motor response to noxious electrical stimulation of the forelimb evaluated every 30 minutes until a stable proportion of frogs were immobile. Each frog received each anesthetic and concentration in random order and allowed at least 14 hours to recover between anesthetic exposures. An overpressure technique based upon the kinetics in the first study was then tested with 4 concentrations of desflurane. For halothane, isoflurane and desflurane respectively; the proportion of frogs immobile in response to stimulus became stable after 510, 480 and 180 minutes, and ED50 values were 1.36, 1.67 and 6.78 % atm. Desflurane ED50 delivered by overpressure was not significantly different at 6.85 % atm. Halothane, isoflurane and desflurane are effective general anesthetics in frogs with potencies similar to those reported in mammals. The time required for anesthetic equilibration is fastest with desflurane and can be hastened further by initial delivery of higher partial pressures.

Oxidative Stress Induced in PCB 126-Exposed Northern Leopard Frogs, Rana pipiens

Northern leopard frogs Rana pipiens exposed to PCB 126 (3,3′,4,4′,5-pentachlorobiphenyl) were examined for hepatic oxidative stress. In a dose-response study, northern leopard frogs were injected intraperitoneally with either PCB 126 in corn oil (0.2, 0.7, 2.3, or 7.8 mg/kg body weight) or corn oil alone. In a time-course study, frogs received 7.8 mg/kg or corn oil alone, and were examined at 1, 2, 3, and 4 wk after dosing. Hepatic concentrations of reduced glutathione (GSH), thiobarbituric acid-reactive substances (TBARS), and total sulfhydryls (total SH), as well as activities of glutathione peroxidase (GSH-P), GSSG reductase (GSSG-R), glucose-6-phosphate dehydrogenase (G-6-PDH), and glutathione S-transferase (GSH-S-T) were measured. In the dose-response experiment, few effects were apparent 1 wk after dosing. In the time-course experiment, significant changes were observed in the 7.8-mg/kg group at 2 wk or more posttreatment. Hepatic concentrations of GSH and TBARS were higher than in corresponding controls at wk 3 and 4; the activities of GSSG-R and GSH-S-T were higher than in controls at wk 2 and 4; and the activity of G-6-PDH was increased at wk 2 and 4. These data collectively indicate that altered glutathione metabolism and oxidative stress occurred and were indicative of both toxicity and induction of protective mechanisms in frogs exposed to PCB. A similar delay in response was reported in fish and may relate to lower metabolic rate and physiological reactions in ectothermic vertebrates.

Isoflurane Potency in the Northern Leopard Frog Rana pipiens is Similar to That in Mammalian Species and is Unaffected by Decerebration

Amphibians are commonly used in biomedical research, including studies of mechanisms of anaesthetic action. There is, however, little published work describing the kinetics of inhaled anaesthetic agents or the potency of isoflurane in amphibians. Ten Northern leopard frogs were exposed to a constant isoflurane concentration of 1.0%, 1.2% or 1.5% atm for 4 h, and their response to a noxious stimulus was tested every 20 min. Each frog was anaesthetized with each concentration in random order and allowed at least 16 h to recover between anaesthetic exposures. Frogs were then pithed and the protocol was repeated. Frogs first displayed immobility during stimulus application at 80 min, and the proportion of animals becoming immobile steadily increased to reach a stable level at 4 h. The 50% effective dose for isoflurane in intact and pithed frogs did not differ, and was 1.15 and 1.25% atm, respectively. The potency of isoflurane in leopard frogs was similar to that reported in mammalian species. Cutaneous uptake of anaesthetic is effective given sufficient time, approximately 4 h in this study. Forebrain structures appear to be unimportant for the immobilizing action of isoflurane in the frog.

Oncogenic herpesvirus DNA absence in kidney cell lines established from the northern leopard frog Rana pipiens

Oncogenic herpesvirus DNA absence in kidney cell lines established from the northern leopard frog Rana pipiens

A Model of the Dynamic Exchanges of Water and Energy between a Terrestrial Amphibian and Its Environment

Mechanistic models of the H2O and energy dynamic interrelationships between a terrestrial amphibian and its environments were developed and applied in a study of the temperature and water relations of the northern leopard frog Rana pipiens Schreber. The models illustrate the relative importance of air temperature, relative humidity, wind speed, absorbed solar and thermal radiation, substrate temperature, and soil H2O potential on the core temperatures, hydration levels, and rates of hydration level change during desiccation and rehydration for leopard frogs of different size. Leopard frogs' core temperatures are influenced most by ambient air and substrate temperatures, whereas absorbed radiation has a subordinant effect. Evaporative H2O loss rates are strongly influenced by absorbed radiation and virtually not influenced at all by substrate temperature (relative humidity, air temperature, and wind speed were also shown to be strongly influential on evaporative H2O loss). Water uptake from wet soils (ψsoil > —150 mb) is determined primarily by the properties of the frog, whereas H2O uptake from relatively drier soils (ψsoil < —300 mb) is determined by the conductive properties of the soil. Results of computer simulations suggest that leopard frogs in southern Wisconsin environments should not be found at great distances from standing H2O or soils with H2O potentials < —150 mb. Data taken from the literature and viewed in context of the theory of H2O exchange between an amphibian and soil, suggests that leopard frogs may rarely venture from saturated soils (ψ soil = 0). Results of simulations also imply that leopard frogs in most natural environmental circumstances will not generally have core temperatures greatly different from ambient air temperatures; thus, implying that any behavioral thermoregulatory ability would likely be crude. The modeling approach provides an extremely practical technique to study mechanistic interactions of the many environmental variables involved in the temperature and water relations of terrestrial amphibians.