Growth and development of larval green frogs (Rana clamitans) exposed to multiple doses of an insecticide

USGS Publications Warehouse

Boone, M.D.; Bridges, C.M.; Rothermel, B.B.

2001-01-01

Our objective was to determine how green frogs (Rana clamitans) are affected by multiple exposures to a sublethal level of the carbamate insecticide, carbaryl, in outdoor ponds. Tadpoles were added to 1,000-1 ponds at a low or high density which were exposed to carbaryl 0, 1, 2, or 3 times. Length of the larval period, mass, developmental stage, tadpole survival, and proportion metamorphosed were used to determine treatment effects. The frequency of dosing affected the proportion of green frogs that reached metamorphosis and the developmental stage of tadpoles. Generally, exposure to carbaryl increased rates of metamorphosis and development. The effect of the frequency of carbaryl exposure on development varied with the density treatment; the majority of metamorphs and the most developed tadpoles came from high-density ponds exposed to carbaryl 3 times. This interaction suggests that exposure to carbaryl later in the larval period stimulated metamorphosis, directly or indirectly, under high-density conditions. Our study indicates that exposure to a contaminant can lead to early initiation of metamorphosis and that natural biotic factors can mediate the effects of a contaminant in the environment.

Diet of introduced bullfrogs (Rana catesbeiana): Predation on and diet overlap with native frogs on Daishan Island, China

USGS Publications Warehouse

Wu, Zhengjun; Li, Y.; Wang, Y.; Adams, Michael J.

2005-01-01

We examined diet of introduced Bullfrogs (Rana catesbeiana) and three native frog species (Rana limnocharis, Rana nigromaculata, and Bufo bufo gargarizans) co-occurring at a group of ponds on Daishan Island, east of China, to gain insight into the nature of potential interactions between Bullfrogs and native frog species. For postmetamorphic Bullfrogs, aquatic prey items dominated volumetrically. Prey size, diet volume and volumetric percentage of native frogs in diet increased with Bullfrog body size. The number and volumetric percentage of native frogs in the diet were not different for female and male Bullfrogs, and both were higher for adults than for juveniles. Diet overlap between males and juveniles was higher than that between males and females and between females and juveniles. Diet overlap with each native frog species of male Bullfrogs was lower than that of female Bullfrogs and juvenile Bullfrogs. We did not exam effects of Bullfrogs on native frogs but our results suggest that the primary threat posed by juvenile Bullfrogs to native frogs on Daishan Island is competition for food, whereas the primary threat posed by male Bullfrogs is direct predation. Female Bullfrogs may threaten native frogs by both competition and predation. These differences among Bullfrog groups may be attributed to differences in body size and microhabitat use.

Embryogenesis and laboratory maintenance of the foam-nesting túngara frogs, genus Engystomops (= Physalaemus)

PubMed Central

Romero-Carvajal, Andrés; Sáenz-Ponce, Natalia; Venegas-Ferrín, Michael; Almeida-Reinoso, Diego; Lee, Chanjae; Bond, Jennifer; Ryan, Michael J.; Wallingford, John B.; del Pino, Eugenia M.

2010-01-01

The vast majority of embryological research on amphibians focuses on just a single genus of frogs, Xenopus. To attain a more comprehensive understanding of amphibian development, experimentation on non-model frogs will be essential. Here, we report on the early development, rearing, and embryological analysis of túngara frogs (genus Engystomops, also called Physaleamus). The frogs Engystomops pustulosus, Engystomops coloradorum and Engystomops randi construct floating foam-nests with small eggs. We define a table of 23 stages for the developmental period in the foam-nest. Embryos were immunostained against Lim1, neural, and somite-specific proteins and the expression pattern of RetinoBlastoma Binding Protein 6 (RBBP6) was analyzed by in situ hybridization. Due to their brief life-cycle, frogs belonging to the genus Engystomops are attractive for comparative and genetic studies of development. PMID:19384855

FROGS (Friends of Granites) report

NASA Astrophysics Data System (ADS)

Miller, Calvin

This VGP News, which is devoted to petrology, is a good one for noting the existence of FROGS. FROGS is, as the name suggests, an informal organization of people whose research relates in one way or another to granitic rocks. Its purpose has been to promote communication among geoscientists with different perspectives and concerns about felsic plutonism. Initially, a major focus was experimental petrology and integration of field-oriented and lab-oriented viewpoints; now that there is the opportunity to communicate with the Eos readership, an obvious additional goal will be to bring together volcanic and plutonic views of felsic magmatism.FROGS first gathered in late 1982 under the guidance of E-an Zen and Pete Toulmin (both at U.S. Geological Survey (USGS), Reston, Va.), who saw a need for greater interaction among those interested in granites and for renewed, focused experimental investigations. They produced two newsletters (which were sent out by direct mail) and organized an informal meeting at the Geological Society of America meeting at Indianapolis, Ind., and then turned over the FROG reins to Sue Kieffer (USGS, Flagstaff, Ariz.) and John Clemens (Arizona State University, Tempe). They generated another newsletter, which was directly mailed to a readership that had grown beyond 200.

Development of the pseudothumb in frogs

PubMed Central

Tokita, Masayoshi; Iwai, Noriko

2010-01-01

Frogs have highly conserved hand and foot morphology, possessing four fingers and five toes. As an exception, two Japanese ranid frog species, the Otton frog Babina subaspera and the dagger frog Babina holsti, possess a unique thumb-like structure (the pseudothumb) in the forelimb, giving an appearance of a total of five fingers on the hand. To obtain insights into the developmental mechanisms that generate this novel character, we investigated the hand morphogenesis of the Otton frog. The unique morphological pattern of the pseudothumb was already established in juveniles. Surprisingly, the bud-like structure, which is similar to the area of inductive activity (e.g. feather buds in birds and the carapacial ridge in turtles), was detected over the site where the future prepollex develops in larvae. By contrast, this bud-like structure was not found in larvae of other ranid species. We discuss possible scenarios that would favour the evolution of this very unusual trait in frogs. PMID:20147308

The evolution of reproductive diversity in Afrobatrachia: A phylogenetic comparative analysis of an extensive radiation of African frogs.

PubMed

Portik, Daniel M; Blackburn, David C

2016-09-01

The reproductive modes of anurans (frogs and toads) are the most diverse of terrestrial vertebrates, and a major challenge is identifying selective factors that promote the evolution or retention of reproductive modes across clades. Terrestrialized anuran breeding strategies have evolved repeatedly from the plesiomorphic fully aquatic reproductive mode, a process thought to occur through intermediate reproductive stages. Several selective forces have been proposed for the evolution of terrestrialized reproductive traits, but factors such as water systems and co-evolution with ecomorphologies have not been investigated. We examined these topics in a comparative phylogenetic framework using Afrobatrachian frogs, an ecologically and reproductively diverse clade representing more than half of the total frog diversity found in Africa (∼400 species). We infer direct development has evolved twice independently from terrestrialized reproductive modes involving subterranean or terrestrial oviposition, supporting evolution through intermediate stages. We also detect associations between specific ecomorphologies and oviposition sites, and demonstrate arboreal species exhibit an overall shift toward using lentic water systems for breeding. These results indicate that changes in microhabitat use associated with ecomorphology, which allow access to novel sites for reproductive behavior, oviposition, or larval development, may also promote reproductive mode diversity in anurans. © 2016 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Semaphoring in an earless frog: the origin of a novel visual signal.

PubMed

Lindquist, E D; Hetherington, T E

1998-10-01

Social communication in anuran amphibians (frogs and toads) is mediated predominantly by acoustic signals. Unlike most anurans, the Panamanian golden frog, Atelopus zeteki, lacks a standard tympanic middle ear and appears to have augmented its communicatory repertoire to include rotational limb motions as visual signals, referred to here as semaphores. The communicatory nature of semaphoring was inferred from experimental manipulations using mirrored self-image presentations and nonresident introductions. Male frogs semaphored significantly more when presented with a mirrored self-image than with a nonreflective control. Novel encounters between resident males and nonresident frogs demonstrated that semaphores were used directionally and were displayed toward target individuals. Females semaphored frequently and this observation represents a rare case of signaling by females in a typically male-biased communicatory regime. Semaphore actions were clearly linked to a locomotory gait pattern and appear to have originated as an elaboration of a standard stepping motion.

Effect of dietary carotenoids on vitamin A status and skin pigmentation in false tomato frogs (Dyscophus guineti).

PubMed

Brenes-Soto, Andrea; Dierenfeld, Ellen S

2014-01-01

Several species in captivity develop nutritional diseases including vitamin A deficiency; cases of this disease have been documented in amphibians, which may be linked to an insectivorous diet lacking in vitamin A or carotenoids. Adults and young of Dyscophus guineti were fed three diets over 9 weeks to evaluate effects on carotenoids and vitamin A status and skin pigmentation. Feeder crickets were either supplemented with soy oil (control, CON), soy oil enriched with β-carotene (BC) or mixed carotenoids (MIX) by direct injection of known dosages. Vitamin A from feeder crickets (measured as retinol) was higher in insects supplemented with both BC and MIX; (P=0.0001) and plasma retinol concentrations were significantly higher in frogs fed MIX (P<0.02). Results suggest that both false tomato frogs and feeder crickets could receive some provitamin A activity through consumption of diets supplemented with β-carotene, and xanthophylls like lutein and zeaxanthin. Pigmentation was evaluated weekly through the use of visual color charts, as well as quantitatively using a hand-held spectrophotometer. MIX diets had a significant effect on skin color values (P<0.0001), as well as on lightness (P=0.0005) and hue (P=0.0022). Results indicated that frogs fed with BC changed to yellower colors, and frogs fed with MIX changed to oranger colors. Visual color chart observations also scored significantly different between CON and MIX diets (P<0.05); the animals fed MIX also appeared oranger according to the qualitative observations. Dietary supplements with carotenoids resulted in color changes and higher circulating retinol concentrations in false tomato frogs. These pigments may provide provitamin A activity in diets, thus may support improved nutrition and health of captive-fed insectivorous amphibians. © 2014 Wiley Periodicals Inc.

Release of “neurokinin” on nervous and electrical stimulation of a frog stomach muscle preparation

PubMed Central

Singh, I.

1964-01-01

Activation of a frog stomach muscle preparation by electrical stimulation of a vagus nerve or by direct stimulation released two polypeptides. One was destroyed by trypsin or chymotrypsin in about 10 min; the activity of the other was enhanced by trypsin for about 10 min, but was destroyed by chymotrypsin. Similar stimulation of dog stomach muscle did not release these polypeptides. Correspondingly, the transmission from vagus nerve to stomach muscle in the frog was resistant to atropine, but was blocked by atropine in the dog. PMID:14190475

Field guide to malformations of frogs and toads: with radiographic interpretations

USGS Publications Warehouse

Meteyer, Carol U.

2000-01-01

In 1995, students found numerous malformed frogs on a field trip to a Minnesota pond. Since that time, reports of malformed frogs have increased dramatically. Malformed frogs have now been reported in 44 states in 38 species of frogs, and 19 species of toads. Estimates as high as 60% of the newly metamorphosed frog populations have had malformations at some ponds (NARCAM, ’99). The wide geographic distribution of malformed frogs and the variety of malformations are a concern to resource managers, research scientists and public health officials. The potential for malformations to serve as a signal of ecosystem disruption, and the affect this potential disruption might have on other organisms that share those ecosystems, has not been resolved. Malformations represent an error that occurred early in development. The event that caused the developmental error is temporally distant from the malformation we see in the fully developed animal. Knowledge of normal developmental principles is necessary to design thoughtful investigations that will define the events involved in abnormal development in wild frog populations.Development begins at the time an egg is fertilized and progresses by chemical communication between cells and cell layers. This communication is programmed through gene expression. Malformations represent primary errors in development, errors in chemical communication or translation of genetic information. Deformations arise later in development and usually result from the influence of mechanical factors (such as amputation) that alter shape or anatomy of a structure that has developed normally. The occurrence and the type of malformations are influenced by the type of error or insult as well as the timing of the error (the developmental stage at which the error occurred). The appearance of the malformation can therefore provide clues that suggest when the error may have occurred. If the malformation is an incomplete organ, such as an incomplete limb, the factor or insult acted during a susceptible period prior to organ completion. Although defining the anatomy of the malformed metamorphosed frog can give us an idea of the approximate window during which the developmental insult was initiated, and might even suggest the type of insult that may have occurred, the morphology of the malformation does not define the cause. To define causes and mechanisms of frog malformations we need to use well designed investigations that are different from traditional tests used in acute toxicity or disease pathogenicity studies. When investigating malformations in metamorphosed frogs, we are looking at the affect of exposure to an agent that occurred early in tadpole development. Therefore investigations to determine causes of malformations need to look at agents that are present in the tadpoles or their environments at these early developmental times. Laboratory experiments need to expose embryos and tadpoles to suspect agents at appropriate developmental stages and look at acute results, such as toxicity and death, as well as following the developmental process to completion to determine the impact of the agent on the developing tadpole and the fully developed frog. This means holding animals past metamorphic climax to assure that the anatomy and physiology of the adult have developed normally.As we look at field collections of abnormal frogs, we need to keep in mind that these collections reflect survivors only. We are looking at malformations that were not fatal to tadpoles. We cannot assume that because we do not collect other malformations, they did not exist. More work needs to be done on the developing tadpole, in the field and in the laboratory, to better elucidate the range, frequency, character and causes of anuran malformations.

Development of the nasal chemosensory organs in two terrestrial anurans: the directly developing frog, Eleutherodactylus coqui (Anura: Leptodactylidae), and the metamorphosing toad, Bufo americanus (Anura: Bufonidae).

PubMed

Jermakowicz, Walter J; Dorsey, David A; Brown, Amy L; Wojciechowski, Karen; Giscombe, Claudette L; Graves, Brent M; Summers, Cliff H; Ten Eyck, Gary R

2004-08-01

Nearly all vertebrates possess an olfactory organ but the vomeronasal organ is a synapomorphy for tetrapods. Nevertheless, it has been lost in several groups of tetrapods, including aquatic and marine animals. The present study examines the development of the olfactory and vomeronasal organs in two terrestrial anurans that exhibit different developmental modes. This study compares the development of the olfactory and vomeronasal organs in metamorphic anurans that exhibit an aquatic larva (Bufo americanus) and directly developing anurans that have eliminated the tadpole (Eleutherodactylus coqui). The olfactory epithelium in larval B. americanus is divided into dorsal and ventral branches in the rostral and mid-nasal regions. The larval olfactory pattern in E. coqui has been eliminated. Ontogeny of the olfactory system in E. coqui embryos starts to vary substantially from the larval pattern around the time of operculum development, the temporal period when the larval stage is hypothesized to have been eliminated. The nasal anatomy of the two frogs does not appear morphologically similar until the late stages of embryogenesis in E. coqui and the terminal portion of metamorphosis in B. americanus. Both species and their respective developing offspring, aquatic tadpoles and terrestrial egg/embryos, possess a vomeronasal organ. The vomeronasal organ develops at mid-embryogenesis in E. coqui and during the middle of the larval period in B. americanus, which is relatively late for neobatrachians. Development of the vomeronasal organ in both frogs is linked to the developmental pattern of the olfactory system. This study supports the hypothesis that the most recent common ancestor of tetrapods possessed a vomeronasal organ and was aquatic, and that the vomeronasal organ was retained in the Amphibia, but lost in some other groups of tetrapods, including aquatic and marine animals. Copyright 2004 Wiley-Liss, Inc.

Frogs Jump Forward: Semantic Knowledge Influences the Perception of Element Motion in the Ternus Display.

PubMed

Hsu, Patty; Taylor, J Eric T; Pratt, Jay

2015-01-01

The Ternus effect is a robust illusion of motion that produces element motion at short interstimulus intervals (ISIs; < 50 ms) and group motion at longer ISIs (> 50 ms). Previous research has shown that the nature of the stimuli (e.g., similarity, grouping), not just ISI, can influence the likelihood of perceiving element or group motion. We examined if semantic knowledge can also influence what type of illusory motion is perceived. In Experiment I, we used a modified Ternus display with pictures of frogs in a jump-ready pose facing forwards or backwards to the direction of illusory motion. Participants perceived more element motion with the forward-facing frogs and more group motion with the backward-facing frogs. Experiment 2 tested whether this effect would still occur with line drawings of frogs, or if a more life-like image was necessary. Experiment 3 tested whether this effect was due to visual asymmetries inherent in the jumping pose. Experiment 4 tested whether frogs in a "non-jumping," sedentary pose would replicate the original effect. These experiments elucidate the role of semantic knowledge in the Ternus effect. Prior knowledge of the movement of certain animate objects, in this case, frogs can also bias the perception of element or group motion.

Pesticides in mountain yellow-legged frogs (Rana muscosa) from the Sierra Nevada Mountains of California, USA

USGS Publications Warehouse

Fellers, G.M.; McConnell, L.L.; Pratt, D.; Datta, S.

2004-01-01

In 1997, pesticide concentrations were measured in mountain yellow-legged frogs (Rana muscosa) from two areas in the Sierra Nevada Mountains of California, USA. One area (Sixty Lakes Basin, Kings Canyon National Park) had large, apparently healthy populations of frogs. A second area (Tablelands, Sequoia National Park) once had large populations, but the species had been extirpated from this area by the early 1980s. The Tablelands is exposed directly to prevailing winds from agricultural regions to the west. When an experimental reintroduction of R. muscosa in 1994 to 1995 was deemed unsuccessful in 1997, the last 20 (reintroduced) frogs that could be found were collected from the Tablelands, and pesticide concentrations in both frog tissue and the water were measured at both the Tablelands and at reference sites at Sixty Lakes. In frog tissues, dichlorodiphenyldichloroethylene (DDE) concentration was one to two orders of magnitude higher than the other organochlorines (46 ?? 20 ng/g wet wt at Tablelands and 17 ?? 8 Sixty Lakes). Both ??-chlordane and trans-nonachlor were found in significantly greater concentrations in Tablelands frog tissues compared with Sixty Lakes. Organophosphate insecticides, chlorpyrifos, and diazinon were observed primarily in surface water with higher concentrations at the Tablelands sites. No contaminants were significantly higher in our Sixty Lakes samples.

Inverse Effects on Growth and Development Rates by Means of Endocrine Disruptors in African Clawed Frog Tadpoles ("Xenopus Laevis")

ERIC Educational Resources Information Center

Hackney, Zachary Carl

2007-01-01

Previous work on fish, frogs, and salamanders, showed the ability for estrogen (EE2) and anthropogenic endocrine disruptors to skew sex ratios and cause hermaphrodism. This study addressed the effects of estrogens on growth and development rates of African clawed frog tadpoles ("Xenopus laevis") during their gender determination stages. The…

Checklist and Simple Identification Key for Frogs and Toads from District IV of The MADA Scheme, Kedah, Malaysia

PubMed Central

Jaafar, Ibrahim; Chai, Teoh Chia; Sah, Shahrul Anuar Mohd; Akil, Mohd Abdul Muin Md.

2009-01-01

A survey was conducted to catalogue the diversity of anurans in District IV of the Muda Agriculture Development Authority Scheme (MADA) in Kedah Darul Aman, Malaysia, from July 1996 to January 1997. Eight species of anurans from three families were present in the study area. Of these, the Common Grass Frog (Fejevarya limnocharis) was the most abundant, followed by Mangrove Frog (Fejevarya cancrivora), Long-legged Frog (Hylarana macrodactyla), and Common Toad (Duttaphrynus melanostictus). Puddle Frog (Occidozyga lima), Taiwanese Giant Frog (Hoplobatrachus rugulosus), and Banded Bullfrog (Kaluola pulchra) were rare during the sampling period, and only one Paddy Frog (Hylarana erythraea) was captured. A simple identification key for the anurans of this area is included for use by scientists and laymen alike. PMID:24575178

Frequency-resolved optical gating with the use of second-harmonic generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeLong, K.W.; Trebino, R.; Hunter, J.

1994-11-01

We discuss the use of second-harmonic generation (SHG) as the nonlinearity in the technique of frequency-resolved optical gating (FROG) for measuring the full intensity and phase evolution of an arbitrary ultrashort pulse. FROG that uses a third-order nonlinearity in the polarization-gate geometry has proved extremely successful, and the algorithm required for extraction of the intensity and the phase from the experimental data is quite robust. However, for pulse intensities less than [similar to] 1 MW, third-order nonlinearities generate insufficient signal strength, and therefore SHG FROG appears necessary. We discuss the theoretical, algorithmic, and experimental considerations of SHG FROG in detail.more » SHG FROG has an ambiguity in the direction of time, and its traces are somewhat unintuitive. Also, previously published algorithms are generally ineffective at extracting the intensity and the phase of an arbitrary laser pulse from the SHG FROG trace. We present an improved pulse-retrieval algorithm, based on the method of generalized projections, that is far superior to the previously published algorithms, although it is still not so robust as the polarization-gate algorithm. We discuss experimental sources of error such as pump depletion and group-velocity mismatch. We also present several experimental examples of pulses measured with SHG FROG and show that the derived intensities and phases are in agreement with more conventional diagnostic techniques, and we demonstrate the high-dynamic-range capability of SHG FROG. We conclude that, despite the above drawbacks, SHG FROG should be useful in measuring low-energy pulses.« less

Techniques for the characterization of sub-10-fs optical pulses: a comparison

NASA Astrophysics Data System (ADS)

Gallmann, L.; Sutter, D. H.; Matuschek, N.; Steinmeyer, G.; Keller, U.

Several methods have been proposed for the phase and amplitude characterization of sub-10-fs pulses with nJ energies. An overview of these techniques is presented, with a focus on the comparison of second-harmonic generation frequency-resolved optical gating (SHG-FROG) and spectral phase interferometry for direct electric-field reconstruction (SPIDER). We describe a collinear FROG variant based on type-II phase-matching that completely avoids the geometrical blurring artifact and use both this and SPIDER for the characterization of sub-10-fs Ti:sapphire laser pulses. The results of both methods are compared in an extensive statistical analysis. From this first direct experimental comparison of FROG and SPIDER, guidelines for accurate measurements of sub-10-fs pulses are derived. We point out limitations of both methods for pulses in this ultrashort pulse regime.

Disease and the extended phenotype: parasites control host performance and survival through induced changes in body plan.

PubMed

Goodman, Brett A; Johnson, Pieter T J

2011-01-01

By definition, parasites harm their hosts. However, some forms of parasite-induced alterations increase parasite transmission between hosts, such that manipulated hosts can be considered extensions of the parasite's phenotype. While well accepted in principle, surprisingly few studies have quantified how parasite manipulations alter host performance and survival under field and laboratory conditions. By interfering with limb development, the trematode Ribeiroia ondatrae causes particularly severe morphological alterations within amphibian hosts that provide an ideal system to evaluate parasite-induced changes in phenotype. Here, we coupled laboratory performance trials with a capture-mark-recapture study of 1388 Pacific chorus frogs (Pseudacris regilla) to quantify the effects of parasite-induced malformations on host locomotion, foraging, and survival. Malformations, which affected ∼ 50% of metamorphosing frogs in nature, caused dramatic reductions in all measures of organismal function. Malformed frogs exhibited significantly shorter jumping distances (41% reduction), slower swimming speeds (37% reduction), reduced endurance (66% reduction), and lower foraging success relative to infected hosts without malformations. Furthermore, while normal and malformed individuals had comparable survival within predator-free exclosures, deformed frogs in natural populations had 22% lower biweekly survival than normal frogs and rarely recruited to the adult population over a two-year period. Our results highlight the ability of parasites to deeply alter multiple dimensions of host phenotype with important consequences for performance and survival. These patterns were best explained by malformation status, rather than infection per se, helping to decouple the direct and indirect effects of parasitism on host fitness.

Disease and the Extended Phenotype: Parasites Control Host Performance and Survival through Induced Changes in Body Plan

PubMed Central

Goodman, Brett A.; Johnson, Pieter T. J.

2011-01-01

Background By definition, parasites harm their hosts. However, some forms of parasite-induced alterations increase parasite transmission between hosts, such that manipulated hosts can be considered extensions of the parasite's phenotype. While well accepted in principle, surprisingly few studies have quantified how parasite manipulations alter host performance and survival under field and laboratory conditions. Methodology/Principal Findings By interfering with limb development, the trematode Ribeiroia ondatrae causes particularly severe morphological alterations within amphibian hosts that provide an ideal system to evaluate parasite-induced changes in phenotype. Here, we coupled laboratory performance trials with a capture-mark-recapture study of 1388 Pacific chorus frogs (Pseudacris regilla) to quantify the effects of parasite-induced malformations on host locomotion, foraging, and survival. Malformations, which affected ∼50% of metamorphosing frogs in nature, caused dramatic reductions in all measures of organismal function. Malformed frogs exhibited significantly shorter jumping distances (41% reduction), slower swimming speeds (37% reduction), reduced endurance (66% reduction), and lower foraging success relative to infected hosts without malformations. Furthermore, while normal and malformed individuals had comparable survival within predator-free exclosures, deformed frogs in natural populations had 22% lower biweekly survival than normal frogs and rarely recruited to the adult population over a two-year period. Conclusions/Significance Our results highlight the ability of parasites to deeply alter multiple dimensions of host phenotype with important consequences for performance and survival. These patterns were best explained by malformation status, rather than infection per se, helping to decouple the direct and indirect effects of parasitism on host fitness. PMID:21633498

Sticking like sticky tape: tree frogs use friction forces to enhance attachment on overhanging surfaces

PubMed Central

Endlein, Thomas; Ji, Aihong; Samuel, Diana; Yao, Ning; Wang, Zhongyuan; Barnes, W. Jon P.; Federle, Walter; Kappl, Michael; Dai, Zhendong

2013-01-01

To live and clamber about in an arboreal habitat, tree frogs have evolved adhesive pads on their toes. In addition, they often have long and slender legs to facilitate not only long jumps, but also to bridge gaps between leaves when climbing. Both adhesive pads and long limbs are used in conjunction, as we will show in this study. Previous research has shown that tree frogs change from a crouched posture (where the limbs are close to the body) to a sprawled posture with extended limbs when clinging on to steeper inclines such as vertical or overhanging slopes. We investigated this change in posture in White's tree frogs (Litoria caerulea) by challenging the frogs to cling onto a tiltable platform. The platform consisted of an array of 24 three-dimensional force transducers, which allowed us to measure the ground reaction forces of the frogs during a tilt. Starting from a crouched resting position, the normal forces on the forelimbs changed sign and became increasingly negative with increasing slope angle of the platform. At about 106°±12°, tilt of the platform the frogs reacted by extending one or two of their limbs outwards. At a steeper angle (131°±11°), the frogs spread out all their limbs sideways, with the hindlimbs stretched out to their maximum reach. Although the extension was strongest in the lateral direction, limbs were significantly extended in the fore–aft direction as well. With the extension of the limbs, the lateral forces increased relative to the normal forces. The large contribution of the in-plane forces helped to keep the angle between the force vector and the platform small. The Kendall theory for the peeling of adhesive tape predicts that smaller peel angles lead to higher attachment forces. We compare our data with the predictions of the Kendall model and discuss possible implications of the sliding of the pads on the surface. The forces were indeed much larger for smaller angles and thus can be explained by peeling theory. PMID:23325755

Ecomorphology and disease: cryptic effects of parasitism on host habitat use, thermoregulation, and predator avoidance.

PubMed

Goodman, Brett A; Johnson, Pieter T J

2011-03-01

Parasites can cause dramatic changes in the phenotypes of their hosts, sometimes leading to a higher probability of predation and parasite transmission. Because an organism's morphology directly affects its locomotion, even subtle changes in key morphological traits may affect survival and behavior. However, despite the ubiquity of parasites in natural communities, few studies have incorporated parasites into ecomorphological research. Here, we evaluated the effects of parasite-induced changes in host phenotype on the habitat use, thermal biology, and simulated predator-escape ability of Pacific chorus frogs (Pseudacris regilla) in natural environments. Frogs with parasite-induced limb malformations were more likely to use ground microhabitats relative to vertical refugia and selected less-angled perches closer to the ground in comparison with normal frogs. Although both groups had similar levels of infection, malformed frogs used warmer microhabitats, which resulted in higher body temperatures. Likely as a result of their morphological abnormalities, malformed frogs allowed a simulated predator to approach closer before escaping and escaped shorter distances relative to normal frogs. These data indicate that parasite-induced morphological changes can significantly alter host behavior and habitat use, highlighting the importance of incorporating the ubiquitous, albeit cryptic, role of parasites into ecomorphological research.

Museum material reveals a frog parasite emergence after the invasion of the cane toad in Australia

PubMed Central

2010-01-01

Background A parasite morphologically indistinguishable from Myxidium immersum (Myxozoa: Myxosporea) found in gallbladders of the invasive cane toad (Bufo marinus) was identified in Australian frogs. Because no written record exists for such a parasite in Australian endemic frogs in 19th and early 20th century, it was assumed that the cane toad introduced this parasite. While we cannot go back in time ourselves, we investigated whether material at the museum of natural history could be used to retrieve parasites, and whether they were infected at the time of their collection (specifically prior to and after the cane toad translocation to Australia in 1935). Results Using the herpetological collection at the Australian Museum we showed that no myxospores were found in any animals (n = 115) prior to the cane toad invasion (1879-1935). The green and golden bell frog (Litoria aurea), the Peron's tree frog (Litoria peronii), the green tree frog (Litoria caerulea) and the striped marsh frog (Limnodynastes peronii) were all negative for the presence of the parasite using microscopy of the gallbladder content and its histology. These results were sufficient to conclude that the population was free from this disease (at the expected minimum prevalence of 5%) at 99.7% confidence level using the 115 voucher specimens in the Australian Museum. Similarly, museum specimens (n = 29) of the green and golden bell frog from New Caledonia, where it was introduced in 19th century, did not show the presence of myxospores. The earliest specimen positive for myxospores in a gallbladder was a green tree frog from 1966. Myxospores were found in eight (7.1%, n = 112) frogs in the post cane toad introduction period. Conclusion Australian wildlife is increasingly under threat, and amphibian decline is one of the most dramatic examples. The museum material proved essential to directly support the evidence of parasite emergence in Australian native frogs. This parasite can be considered one of the luckiest parasites, because it has found an empty niche in Australia. It now flourishes in > 20 endemic and exotic frog species, but its consequences are yet to be fully understood. PMID:20537137

Towards a better understanding of the use of probiotics for preventing chytridiomycosis in Panamanian golden frogs.

PubMed

Becker, Matthew H; Harris, Reid N; Minbiole, Kevin P C; Schwantes, Christian R; Rollins-Smith, Louise A; Reinert, Laura K; Brucker, Robert M; Domangue, Rickie J; Gratwicke, Brian

2011-12-01

Populations of native Panamanian golden frogs (Atelopus zeteki) have collapsed due to a recent chytridiomycosis epidemic. Reintroduction efforts from captive assurance colonies are unlikely to be successful without the development of methods to control chytridiomycosis in the wild. In an effort to develop a protective treatment regimen, we treated golden frogs with Janthinobacterium lividum, a skin bacterium that has been used to experimentally prevent chytridiomycosis in North American amphibians. Although J. lividum appeared to colonize A. zeteki skin temporarily, it did not prevent or delay mortality in A. zeteki exposed to Batrachochytrium dendrobatidis, the causative agent of chytridiomycosis. After introduction of J. lividum, average bacterial cell counts reached a peak of 1.7 × 10(6) cells per frog ~2 weeks after treatment but declined steadily after that. When J. lividum numbers declined to ~2.8 × 10(5) cells per frog, B. dendrobatidis infection intensity increased to greater than 13,000 zoospore equivalents per frog. At this point, frogs began to die of chytridiomycosis. Future research will concentrate on isolating and testing antifungal bacterial species from Panama that may be more compatible with Atelopus skin.

Exposure of northern leopard frogs in the Green Bay ecosystem to polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans is measured by direct chemistry but not hepatic ethoxyresorufin-O-deethylase activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Y.W.; Karasov, W.H.; Patnode, K.A.

1999-10-01

The authors measured concentrations of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) in northern leopard frogs collected from the Green Bay ecosystem and explored the catalytic activity of hepatic cytochrome P450-associated monooxygenase (P450 enzyme) as a biomarker for exposure to aryl hydrocarbon receptor (AhR) agonists. The two hypotheses tested were PCH concentrations in northern leopard frogs would be positively correlated with sediment polychlorinated hydrocarbon (PCH) levels in wetland habitats along a contamination gradient and hepatic ethoxyresorufin-O-deethylase (EROD) activity of northern leopard frogs, which is presumably mediated by aryl hydrocarbon receptor (AhR), would be positively correlated with PCHmore » concentrations in frog carcasses from different collection sites. In 1994 and 1995, frogs from seven sites along the lower Fox River and Green Bay, USA, were assayed for hepatic EROD activities and whole carcass concentrations of PCBs, PCDDs, and PCDFs. Tissue total PCB concentrations ranging from 3 to 154 ng/g were significantly correlated with sediment PCB levels. Only one PCDD and two PCDFs at concentrations of 6 to 8 pg/g were found in the frogs collected with frog body weight and was similar among sites except for Peter's Marsh. No significant correlation was found between EROD activity and carcass PCB concentration. This result was consistent with the fact that the frogs collected from the Green Bay ecosystem had relatively low PCB concentrations compared with what was required for induction in the laboratory.« less

The toxicity of Poison Dart Frog alkaloids against the Fire Ant (Solenopsis invicta)

USDA-ARS?s Scientific Manuscript database

Hundreds of alkaloids, representing over 20 structural classes, have been identified from the skin of neotropical poison frogs (Dendrobatidae). These alkaloids are derived from arthropod prey of the frogs, and are generally are believed to deter vertebrate predators. We developed a method to put ind...

Calling at the highway: The spatiotemporal constraint of road noise on Pacific chorus frog communication.

PubMed

Nelson, Danielle V; Klinck, Holger; Carbaugh-Rutland, Alexander; Mathis, Codey L; Morzillo, Anita T; Garcia, Tiffany S

2017-01-01

Loss of acoustic habitat due to anthropogenic noise is a key environmental stressor for vocal amphibian species, a taxonomic group that is experiencing global population declines. The Pacific chorus frog ( Pseudacris regilla ) is the most common vocal species of the Pacific Northwest and can occupy human-dominated habitat types, including agricultural and urban wetlands. This species is exposed to anthropogenic noise, which can interfere with vocalizations during the breeding season. We hypothesized that Pacific chorus frogs would alter the spatial and temporal structure of their breeding vocalizations in response to road noise, a widespread anthropogenic stressor. We compared Pacific chorus frog call structure and ambient road noise levels along a gradient of road noise exposures in the Willamette Valley, Oregon, USA. We used both passive acoustic monitoring and directional recordings to determine source level (i.e., amplitude or volume), dominant frequency (i.e., pitch), call duration, and call rate of individual frogs and to quantify ambient road noise levels. Pacific chorus frogs were unable to change their vocalizations to compensate for road noise. A model of the active space and time ("spatiotemporal communication") over which a Pacific chorus frog vocalization could be heard revealed that in high-noise habitats, spatiotemporal communication was drastically reduced for an individual. This may have implications for the reproductive success of this species, which relies on specific call repertoires to portray relative fitness and attract mates. Using the acoustic call parameters defined by this study (frequency, source level, call rate, and call duration), we developed a simplified model of acoustic communication space-time for this species. This model can be used in combination with models that determine the insertion loss for various acoustic barriers to define the impact of anthropogenic noise on the radius of communication in threatened species. Additionally, this model can be applied to other vocal taxonomic groups provided the necessary acoustic parameters are determined, including the frequency parameters and perception thresholds. Reduction in acoustic habitat by anthropogenic noise may emerge as a compounding environmental stressor for an already sensitive taxonomic group.

Co-Infection by Chytrid Fungus and Ranaviruses in Wild and Harvested Frogs in the Tropical Andes

PubMed Central

Warne, Robin W.; LaBumbard, Brandon; LaGrange, Seth; Vredenburg, Vance T.; Catenazzi, Alessandro

2016-01-01

While global amphibian declines are associated with the spread of Batrachochytrium dendrobatidis (Bd), undetected concurrent co-infection by other pathogens may be little recognized threats to amphibians. Emerging viruses in the genus Ranavirus (Rv) also cause die-offs of amphibians and other ectotherms, but the extent of their distribution globally, or how co-infections with Bd impact amphibians are poorly understood. We provide the first report of Bd and Rv co-infection in South America, and the first report of Rv infections in the amphibian biodiversity hotspot of the Peruvian Andes, where Bd is associated with extinctions. Using these data, we tested the hypothesis that Bd or Rv parasites facilitate co-infection, as assessed by parasite abundance or infection intensity within individual adult frogs. Co-infection occurred in 30% of stream-dwelling frogs; 65% were infected by Bd and 40% by Rv. Among terrestrial, direct-developing Pristimantis frogs 40% were infected by Bd, 35% by Rv, and 20% co-infected. In Telmatobius frogs harvested for the live-trade 49% were co-infected, 92% were infected by Bd, and 53% by Rv. Median Bd and Rv loads were similar in both wild (Bd = 101.2 Ze, Rv = 102.3 viral copies) and harvested frogs (Bd = 103.1 Ze, Rv = 102.7 viral copies). While neither parasite abundance nor infection intensity were associated with co-infection patterns in adults, these data did not include the most susceptible larval and metamorphic life stages. These findings suggest Rv distribution is global and that co-infection among these parasites may be common. These results raise conservation concerns, but greater testing is necessary to determine if parasite interactions increase amphibian vulnerability to secondary infections across differing life stages, and constitute a previously undetected threat to declining populations. Greater surveillance of parasite interactions may increase our capacity to contain and mitigate the impacts of these and other wildlife diseases. PMID:26726999

Variation in the schedules of somite and neural development in frogs

PubMed Central

Sáenz-Ponce, Natalia; Mitgutsch, Christian; del Pino, Eugenia M.

2012-01-01

The timing of notochord, somite, and neural development was analyzed in the embryos of six different frog species, which have been divided into two groups, according to their developmental speed. Rapid developing species investigated were Xenopus laevis (Pipidae), Engystomops coloradorum, and Engystomops randi (Leiuperidae). The slow developers were Epipedobates machalilla and Epipedobates tricolor (Dendrobatidae) and Gastrotheca riobambae (Hemiphractidae). Blastopore closure, notochord formation, somite development, neural tube closure, and the formation of cranial neural crest cell-streams were detected by light and scanning electron microscopy and by immuno-histochemical detection of somite and neural crest marker proteins. The data were analyzed using event pairing to determine common developmental aspects and their relationship to life-history traits. In embryos of rapidly developing frogs, elongation of the notochord occurred earlier relative to the time point of blastopore closure in comparison with slowly developing species. The development of cranial neural crest cell-streams relative to somite formation is accelerated in rapidly developing frogs, and it is delayed in slowly developing frogs. The timing of neural tube closure seemed to be temporally uncoupled with somite formation. We propose that these changes are achieved through differential timing of developmental modules that begin with the elongation of the notochord during gastrulation in the rapidly developing species. The differences might be related to the necessity of developing a free-living tadpole quickly in rapid developers. PMID:23184997

FrogwatchUSA

USGS Publications Warehouse

Droege, S.

2002-01-01

full text: Frogs and toads are perhaps the most approachable and available of all our wildlife. In many, if not most places, they are abundant. In wetter parts of the East, almost anyone outside on a warm rainy night in spring will hear their dream-like calls, bellows, trills and snores. Even in the deserts of the Southwest, a nocturnal trip after a summer monsoon will yield toads moving across the roads toward a cacophonous orgy of mating and calling in the roadside ditches and desert pools. Birds share with frogs and toads this same sense of presence in our daily lives. But the difference is that birds are like the attractive neighbor who just never gives you the time of day, while frogs are more like the troglodyte who appears regularly to chat, philosophize, and have a beer. Uninvited, frogs appear in our water gardens, toads are on our stoops in the morning, we catch them when we are kids, raise their babies in the aquarium, and feel sorry when we find we have run them over with the lawnmower. When concerns about declining populations of amphibians reached the mass media, the Secretaries' office became involved. In addition to using traditional research mechanisms to investigate the problem, the Secretary also wanted to involve the public directly. The combination of high public appeal and the relative ease with which frog calls can be learned made a large-scale monitoring program for frogs and toads possible. What emerged was a program called Frogwatch USA, modeled after a successful Canadian program with a similar name. A web site was created (www.frogwatch.org) that presented potential frogwatchers with directions and a way to register their site online as well as enter their data. Observers chose where to count frogs depending on what they felt was important. For some it was their backyard, others chose vulnerable wetlands in their neighborhoods, or spots on local refuges and parks. Initially funded at $8,000 a year and then after two years increased to $25,000, most of the first part of this program's life was spent developing the tools and web site to document counts of frogs online. Despite the lack of time available to promote the program, send out press releases and recruit observers, news of the program quickly spread by word of mouth and the electronic media. Many newspaper articles later, we found a large number of people had become involved with counting frogs in their neighborhoods and backyards. Current figures show 1,456 observers who have registered at 1,683 sites logging almost 5,000 visits. These visits yield information on when and what species are calling from wetlands throughout the United States. These records are usually the only records of information about frogs and toads for those sites and become a permanent record that can be revisited in future years. Additionally, when observers make a lot of visits or there are many sites in a region, a phenology of calls can be created that documents when it is most likely in that year for each species to be recorded. Finally, even for those observers whose data we may mistrust and therefore are likely to eliminate from analyses, these people have taken the time to leave their televisions, go outside, and directly experience frogs, toads, and all that occur in Nature. In 1999 it was decided that FrogwatchUSA needed to work with another group that specifically focused on environmental education and outreach. After talking to a number of organizations we found that the National Wildlife Federation, with their Backyard Wildlife Habitat, Endangered Species, and other programs along with their four million members who are interested in nature, would be an excellent match. Thus a partnership was born. After over a year of work between Interior and National Wildlife Federation biologists and lawyers, an agreement has been created that places the Federation as the lead of Frogwatch USA. It will now take care of res

Foothill yellow-legged frog conservation assessment in California

Treesearch

Marc P. Hayes; Clara A. Wheeler; Amy J. Lind; Gregory A. Green; Diane C. Macfarlane

2016-01-01

The foothill yellow-legged frog (Rana boylii) is a stream-breeding amphibian that has experienced significant population declines over a large portion of its historical range. This frog is nearing extirpation in much of the Sierra Nevada region where existing populations are sparse. Water development and diversions are likely to be the primary...

Modelling the growth of the brown frog (Rana dybowskii)

PubMed Central

Du, Xiao-peng; Hu, Zong-fu; Cui, Li-yong

2018-01-01

Well-controlled development leads to uniform body size and a better growth rate; therefore, the ability to determine the growth rate of frogs and their period of sexual maturity is essential for producing healthy, high-quality descendant frogs. To establish a working model that can best predict the growth performance of frogs, the present study examined the growth of one-year-old and two-year-old brown frogs (Rana dybowskii) from metamorphosis to hibernation (18 weeks) and out-hibernation to hibernation (20 weeks) under the same environmental conditions. Brown frog growth was studied and mathematically modelled using various nonlinear, linear, and polynomial functions. The model input values were statistically evaluated using parameters such as the Akaike’s information criterion. The body weight/size ratio (Kwl) and Fulton’s condition factor (K) were used to compare the weight and size of groups of frogs during the growth period. The results showed that the third- and fourth-order polynomial models provided the most consistent predictions of body weight for age 1 and age 2 brown frogs, respectively. Both the Gompertz and third-order polynomial models yielded similarly adequate results for the body size of age 1 brown frogs, while the Janoschek model produced a similarly adequate result for the body size of age 2 brown frogs. The Brody and Janoschek models yielded the highest and lowest estimates of asymptotic weight, respectively, for the body weights of all frogs. The Kwl value of all frogs increased from 0.40 to 3.18. The K value of age 1 frogs decreased from 23.81 to 9.45 in the first four weeks. The K value of age 2 frogs remained close to 10. Graphically, a sigmoidal trend was observed for body weight and body size with increasing age. The results of this study will be useful not only for amphibian research but also for frog farming management strategies and decisions.

Habitat selection, movement patterns, and hazards encountered by northern leopard frogs (Lithobates pipiens) in an agricultural landscape

USGS Publications Warehouse

Knutson, Melinda G.; Herner-Thogmartin, Jennifer H.; Thogmartin, Wayne E.; Kapfer, Joshua M.; Nelson, John

2018-01-01

Telemetry data for 59 Northern Leopard Frogs (Lithobates pipiens) breeding in ponds in Houston and Winona Counties, MN; 2001-2002. Agricultural intensification is causing declines in many wildlife species, including Northern Leopard Frogs (Lithobates pipiens). Specific information about frog movements, habitat selection, and sources of mortality can be used to inform conservation-focused land management and acquisition. We studied Northern Leopard Frogs in southeastern Minnesota, part of the Driftless Area ecoregion, characterized by hills and valleys and a mix of agriculture, forests, small towns and farmsteads. In this area, small farm ponds, originally built to control soil erosion are used by the species for breeding and wintering in addition to riparian wetlands. But, this agricultural landscape may be hazardous for frogs moving between breeding, feeding, and wintering habitats. We surgically implanted transmitters into the peritoneal cavity of 59 Northern Leopard Frogs and tracked them from May to October 2001-2002. The total distance traveled by radio-tagged frogs ranged from 12 to 3316 m, the 95% home range averaged 5.3 ± 1.2 (SE) ha, and the 50% core area averaged 1.05 ± 0.3 (SE) ha. As expected, Northern Leopard Frogs selected wetlands over all other land cover classes and row crops were generally avoided at all levels of selection. Only a few tracked frogs were successful at dispersing (n = 6). Most frogs attempting to disperse (n =31) ended up missing (n = 14), died due to mowing (n = 8), or were recorded as transmitter failure (n = 2) or unknown mortalities (n = 1). For the conservation of Northern Leopard Frogs in this agricultural setting, we must consider both the aquatic and the terrestrial needs of this species. Conservation agencies that restore, manage, and acquire wetlands should consider the hazards posed by land uses adjacent to frog breeding and wintering sites and plan for movement corridors between these locations. For example, grasslands that are mowed or hayed between April and October in the north central U.S. and are adjacent to wetlands, pose a direct threat to frogs because these cultivated grasslands are primary locations for summer occupancy. When conservation land managers are selecting sites for acquisition or restoration they should avoid investments that will situate the wetland adjacent to heavily travelled roads and agricultural lands likely to be mowed or hayed. Increasing habitat amount and quality at amphibian breeding, feeding and wintering sites should reduce the energy required and hazards associated with moving long distances. Large, diverse wetlands probably provide all of the requirements needed by Northern Leopard Frogs for survival including food, shelter, breeding and overwintering areas.

Regional decline of an iconic amphibian associated with elevation, land-use change, and invasive species.

PubMed

Johnson, Pieter T J; McKenzie, Valerie J; Peterson, Anna C; Kerby, Jacob L; Brown, Jennifer; Blaustein, Andrew R; Jackson, Tina

2011-06-01

Ecological theory predicts that species with restricted geographic ranges will have the highest probability of extinction, but species with extensive distributions and high population densities can also exhibit widespread population losses. In the western United States populations of northern leopard frogs (Lithobates pipiens)-historically one of the most widespread frogs in North America-have declined dramatically in abundance and geographic distribution. To assess the status of leopard frogs in Colorado and evaluate causes of decline, we coupled statewide surveys of 196 historically occupied sites with intensive sampling of 274 wetlands stratified by land use. We used an information-theoretic approach to evaluate the contributions of factors at multiple spatial extents in explaining the contemporary distribution of leopard frogs. Our results indicate leopard frogs have declined in Colorado, but this decline was regionally variable. The lowest proportion of occupied wetlands occurred in eastern Colorado (2-28%), coincident with urban development and colonization by non-native bullfrogs (Lithobates catesbeianus). Variables at several spatial extents explained observed leopard frog distributional patterns. In low-elevation wetlands introduced fishes, bullfrogs, and urbanization or suburbanization associated negatively with leopard frog occurrence, whereas wetland area was positively associated with occurrence. Leopard frogs were more abundant and widespread west of the Continental Divide, where urban development and bullfrog abundance were low. Although the pathogenic chytrid Batrachochytrium dendrobatidis (Bd) was not selected in our best-supported models, the nearly complete extirpation of leopard frogs from montane wetlands could reflect the individual or interactive effects of Bd and climate patterns. Our results highlight the importance of considering multiple, competing hypotheses to explain species declines, particularly when implicated factors operate at different spatial extents. ©2011 Society for Conservation Biology.

Cryoprotectants and Extreme Freeze Tolerance in a Subarctic Population of the Wood Frog

PubMed Central

Costanzo, Jon P.; Reynolds, Alice M.; do Amaral, M. Clara F.; Rosendale, Andrew J.; Lee, Richard E.

2015-01-01

Wood frogs (Rana sylvatica) exhibit marked geographic variation in freeze tolerance, with subarctic populations tolerating experimental freezing to temperatures at least 10-13 degrees Celsius below the lethal limits for conspecifics from more temperate locales. We determined how seasonal responses enhance the cryoprotectant system in these northern frogs, and also investigated their physiological responses to somatic freezing at extreme temperatures. Alaskan frogs collected in late summer had plasma urea levels near 10 μmol ml-1, but this level rose during preparation for winter to 85.5 ± 2.9 μmol ml-1 (mean ± SEM) in frogs that remained fully hydrated, and to 186.9 ± 12.4 μmol ml-1 in frogs held under a restricted moisture regime. An osmolality gap indicated that the plasma of winter-conditioned frogs contained an as yet unidentified osmolyte(s) that contributed about 75 mOsmol kg-1 to total osmotic pressure. Experimental freezing to –8°C, either directly or following three cycles of freezing/thawing between –4 and 0°C, or –16°C increased the liver’s synthesis of glucose and, to a lesser extent, urea. Concomitantly, organs shed up to one-half (skeletal muscle) or two-thirds (liver) of their water, with cryoprotectant in the remaining fluid reaching concentrations as high as 0.2 and 2.1 M, respectively. Freeze/thaw cycling, which was readily survived by winter-conditioned frogs, greatly increased hepatic glycogenolysis and delivery of glucose (but not urea) to skeletal muscle. We conclude that cryoprotectant accrual in anticipation of and in response to freezing have been greatly enhanced and contribute to extreme freeze tolerance in northern R. sylvatica. PMID:25688861

The biological significance of acoustic stimuli determines ear preference in the music frog.

PubMed

Xue, Fei; Fang, Guangzhan; Yang, Ping; Zhao, Ermi; Brauth, Steven E; Tang, Yezhong

2015-03-01

Behavioral and neurophysiological studies support the idea that right ear advantage (REA) exists for perception of conspecific vocal signals in birds and mammals. Nevertheless, few studies have focused on anuran species that typically communicate through vocalization. The present study examined the direction and latencies of orientation behaviors in Emei music frogs (Babina daunchina) produced in response to six auditory stimuli emitted by a speaker placed directly behind the subjects. The stimuli included male advertisement calls produced from within burrow nests, which have been shown to be highly sexually attractive (HSA), calls produced from outside burrows, which are of low sexual attractiveness (LSA), screech calls produced when frogs are attacked by snakes, white noise, thunder and silence. For all sound stimuli except the screech, the frogs preferentially turned to the right. Right ear preference was strongest for HSA calls. For the screech and thunder stimuli, there was an increased tendency for subjects to move further from the speaker rather than turning. These results support the idea that in anurans, right ear preference is associated with perception of positive or neutral signals such as the conspecific advertisement call and white noise, while a left ear preference is associated with perception of negative signals such as predatory attack. © 2015. Published by The Company of Biologists Ltd.

Natural levels of abnormalities in the trilling frog (neobactrachus centralis) at the Olympic dam mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Read, J.L.; Tyler, M.J.

1994-07-01

Frogs are more susceptible than most vertebrates to environmental contaminants. Unlike amniotes, the frog egg is not protected by a semi-impervious shell, and hence is readily exposed to pollutants. In addition, tadpoles develop in wetlands to which many noxious substances drain from the surrounding landscape. Coupled with this high exposure rate, frogs are also very sensitive to trace elements, some pesticides, heavy metals especially when coupled with exposure to low pH and ionizing radiation. Frogs commonly exhibit discernible deformities following exposure to teratogenic contaminants, and therefore are valuable indicators of the existence of noxious substances in the environment. The abundancemore » and ease of sampling of frogs, along with their sensitivity to environmental contaminants, makes them ideal organisms for environmental monitoring in the Australian arid zone. The study of abnormalities in frogs has become an integral part of the Environmental Management Programme of the Olympic Dam Operations (ODO) copper-uranium-gold-silver mine in northern South Australia. The Trilling Frog (Neobatrachus centralis) is the only frog species which has been recorded at Olympic Dam. It is likely that these frogs, are relatively sedentary, thus enhancing their value as indicator organisms. A pilot survey in 1989 documented frog deformity levels comparable to those found at undisturbed sites in Australia and in other countries. This paper reports on larger study conducted in February and March 1992 when heavy rains provided another opportunity to survey the frog population. The low levels of abnormalities support the conclusion that N. centralis at Olympic Dam does not appear to be accumulating or being influenced by the very low levels of radionuclides present here.« less

Dynamic near-infrared imaging reveals transient phototropic change in retinal rod photoreceptors.

PubMed

Lu, Rongwen; Levy, Alexander M; Zhang, Qiuxiang; Pittler, Steven J; Yao, Xincheng

2013-10-01

Stiles-Crawford effect (SCE) is exclusively observed in cone photoreceptors, but why the SCE is absent in rod photoreceptors is still a mystery. In this study, we employed dynamic near infrared light imaging to monitor photoreceptor kinetics in freshly isolated frog and mouse retinas stimulated by oblique visible light flashes. It was observed that retinal rods could rapidly (onset: ∼10 ms for frog and 5 ms for mouse; time-to-peak: ∼200 ms for frog and 30 ms for mouse) shift toward the direction of the visible light, which might quickly compensate for the loss of luminous efficiency due to oblique illumination. In contrast, such directional movement was negligible in retinal cones. Moreover, transient rod phototropism could contribute to characteristic intrinsic optical signal (IOS). We anticipate that further study of the transient rod phototropism may not only provide insight into better understanding of the nature of vision but also promise an IOS biomarker for functional mapping of rod physiology at high resolution.

Mapping anuran habitat suitability to estimate effects of grassland and wetland conservation programs

USGS Publications Warehouse

Mushet, David M.; Euliss, Ned H.; Stockwell, Craig A.

2012-01-01

The conversion of the Northern Great Plains of North America to a landscape favoring agricultural commodity production has negatively impacted wildlife habitats. To offset impacts, conservation programs have been implemented by the U.S. Department of Agriculture and other agencies to restore grassland and wetland habitat components. To evaluate effects of these efforts on anuran habitats, we used call survey data and environmental data in ecological niche factor analyses implemented through the program Biomapper to quantify habitat suitability for five anuran species within a 196 km2 study area. Our amphibian call surveys identified Northern Leopard Frogs (Lithobates pipiens), Wood Frogs (Lithobates sylvaticus), Boreal Chorus Frogs (Pseudacris maculata), Great Plains Toads (Anaxyrus cognatus), and Woodhouse’s Toads (Anaxyrus woodhousii) occurring within the study area. Habitat suitability maps developed for each species revealed differing patterns of suitable habitat among species. The most significant findings of our mapping effort were 1) the influence of deep-water overwintering wetlands on suitable habitat for all species encountered except the Boreal Chorus Frog; 2) the lack of overlap between areas of core habitat for both the Northern Leopard Frog and Wood Frog compared to the core habitat for both toad species; and 3) the importance of conservation programs in providing grassland components of Northern Leopard Frog and Wood Frog habitat. The differences in habitats suitable for the five species we studied in the Northern Great Plains, i.e., their ecological niches, highlight the importance of utilizing an ecosystem based approach that considers the varying needs of multiple species in the development of amphibian conservation and management plans.

Effects of environmentally relevant sub-chronic atrazine concentrations on African clawed frog (Xenopus laevis) survival, growth and male gonad development.

PubMed

Rimayi, Cornelius; Odusanya, David; Weiss, Jana M; de Boer, Jacob; Chimuka, Luke; Mbajiorgu, Felix

2018-06-01

Sub-chronic toxicity of environmentally relevant atrazine concentrations on exposed tadpoles and adult male African clawed frogs (Xenopus laevis) was evaluated in a quality controlled laboratory for 90 days. The aim of this study was to determine the effects of atrazine on the survival, growth and gonad development of African clawed frogs. After exposure of tadpoles to atrazine concentrations of 0 (control), 0.01, 200 and 500 μg L -1 in water, mortality rates of 0, 0, 3.3 and 70% respectively were recorded for the 90 day exposure period. Morphometry showed significantly reduced tadpole mass in the 500 μg L -1 atrazine exposed tadpoles (p < 0.05). Light microscopy on testes of adult frogs exposed to the same atrazine concentrations using hematoxylin and eosin (H&E) and Van Gieson staining techniques revealed gonadal atrophy, disruption of germ cell lines, seminiferous tubule structure damage and formation of extensive connective tissue around seminiferous tubules of frogs exposed to 200 μg L -1 and 500 μg L -1 atrazine concentrations. Ultrastructural analysis of the cellular organelles using transmission electron microscopy (TEM) revealed significant amounts of damaged mitochondria in testosterone producing Leydig cells as well as Sertoli cells. Biochemical analysis revealed reduced serum testosterone levels in adult frogs at all exposure levels as well as presence of six atrazine metabolites in frog serum and liver. The results indicate that atrazine concentrations greater than the calculated LC50 of 343.7 μg L -1 cause significant mortality in tadpoles, while concentrations ≥200 μg L -1 adversely affect reproductive health of adult frogs and development of tadpoles sub-chronically exposed to atrazine. Copyright © 2018 Elsevier B.V. All rights reserved.

Dynamics of testis-ova in a wild population of Japanese pond frogs, Rana nigromaculata.

PubMed

Kobayashi, Tohru; Kumakura, Masahiko; Yoshie, Sumio; Sugishima, Tomomi; Horie, Yoshifumi

2015-02-01

Although many studies have reported the occurrence of testis-ova in wild frog populations, the origin and trigger of testis-ova differentiation/development remain unclear. A high frequency of testis-ova has been previously reported for wild populations of the Japanese pond frog, Rana nigromaculata (cf. Iwasawa and Asai, '59). In the present study, we aimed to clarify the dynamics of testis-ova in this frog species, including the origin and artificial induction of testis-ova. Testis-ova were observed in both mature frogs and puberty-stage frogs (i.e., 0- and 1-year-old frogs). However, the early stages of testis-ova (~pachytene stage) were mostly observed in puberty-stage male frogs at the onset of spermatogenesis. The early stages of testis-ova were observed in the cysts of early secondary spermatogonia and the single cysts of the primary spermatogonium. This finding indicates that testis-ova differentiation occurs during spermatogonial proliferation and that it is correlated with the initiation of spermatogenesis. We also examined whether estrogen exposure induced testis-ova differentiation and how it is correlated with the progression of spermatogenesis. When 1-year-old frogs were exposed to estradiol-17β during spring (i.e., when spermatogenesis was initiated), testis-ova differentiation was induced in a dose-dependent manner. However, this phenomenon did not occur in 1-year-old frogs during summer, (i.e., when the transition from spermatogonia to spermatocytes mainly occurs). These results present the first evidence that testis-ova of the Japanese pond frog are derived from primary and early secondary spermatogonia, and that estrogen exposure induces testis-ova differentiation accompanied by the initiation of spermatogenesis. © 2015 Wiley Periodicals, Inc.

Molecular evidence for the early history of living amphibians.

PubMed

Feller, A E; Hedges, S B

1998-06-01

The evolutionary relationships of the three orders of living amphibians (lissamphibians) has been difficult to resolve, partly because of their specialized morphologies. Traditionally, frogs and salamanders are considered to be closest relatives, and all three orders are thought to have arisen in the Paleozoic (>250 myr). Here, we present evidence from the DNA sequences of four mitochondrial genes (2.7 kilobases) that challenges the conventional hypothesis and supports a salamander-caecilian relationship. This, in light of the fossil record and distribution of the families, suggests a more recent (Mesozoic) origin for salamanders and caecilians directly linked to the initial breakup of the supercontinent Pangaea. We propose that this single geologic event isolated salamanders and archaeobatrachian frogs on the northern continents (Laurasia) and the caecilians and neobatrachian frogs on the southern continents (Gondwana). Among the neobatrachian frog families, molecular evidence supports a South American clade and an African clade, inferred here to be the result of mid-Cretaceous vicariance. Copyright 1998 Academic Press.

Defining anural malformations in the context of a developmental problem

USGS Publications Warehouse

Meteyer, C.U.; Cole, Rebecca A.; Converse, K.A.; Docherty, D.E.; Wolcott, M.; Helgen, J.C.; Levey, R.; Eaton-Poole, L.; Burkhart, J.G.

2000-01-01

This paper summarizes terminology and general concepts involved in animal development for the purpose of providing background for the study and understanding of frog malformations. The results of our radiographic investigation of rear limb malformations in Rana pipiens provide evidence that frog malformations are the product of early developmental errors. Although bacteria, parasites and viruses were identified in these metamorphosed frogs, the relevant window to look for the teratogenic effect of these agents is in the early tadpole stage during limb development. As a result, our microbiological findings must be regarded as inconclusive relative to determining their contribution to malformations because we conducted our examinations on metamorphosed frogs not tadpoles. Future studies need to look at teratogenic agents (chemical, microbial, physical or mechanical) that are present in the embryo, tadpole, and their environments at the stages of development that are relevant for the malformation type. The impact of these teratogenic agents then needs to be assessed in appropriate animal models using studies that are designed to mimic field conditions. The results of these laboratory tests should then be analyzed in such a way that will allow comparison with the findings in the wild-caught tadpoles and frogs.

Pathological Study of Blood Parasites in Rice Field Frogs, Hoplobatrachus rugulosus (Wiegmann, 1834)

PubMed Central

Sailasuta, Achariya; Satetasit, Jetjun; Chutmongkonkul, Malinee

2011-01-01

One hundred and forty adult rice field frogs, Hoplobatrachus rugulosus (Wiegmann, 1834), were collected in Srakaew province, Thailand. For blood parasite examination, thin blood smears were made and routinely stained with Giemsa. The results showed that 70% of the frogs (98/140) were infected with 5 species of blood parasites, including a Trypanosoma rotatorium-like organism, Trypanosoma chattoni, Hepatozoon sp. a, Hepatozoon sp. b, and Lankesterella minima. Pathological examination of the liver, lung, spleen, and kidney of the frogs that were apparently infected with one of these blood parasites were collected and processed by routine histology and subsequently stained with haematoxylin and eosin. Histopathological findings associated with the Trypanosoma rotatorium-like organism and Trypanosoma chattoni-infected frogs showed no pathological lesions. Hepatozoon sp. a and Hepatozoon sp. b-infected frogs developed inflammatory lesions predominantly in the liver, demonstrating granuloma-like lesions with Hepatozoon sp. meronts at the centre. Tissue sections of Lankesterella minima-infected frogs also showed lesions. Liver and spleen showed inflammatory lesions with an accumulation of melanomacrophage centres (MMCs) surrounding the meronts and merozoites. It is suggested that Hepatozoon sp. a, Hepatozoon sp. b, and Lankesterella minima-infections are capable of producing inflammatory lesions in the visceral organs of rice field frogs, and the severity of lesions is tentatively related to levels of parasitemia. PMID:21918731

Use of femur bone density to segregate wild from farmed Dybowski's frog (Rana dybowskii).

PubMed

Yang, Shu Hui; Huang, Xiao Ming; Xia, Rui; Xu, Yan Chun; Dahmer, Thomas D

2011-04-15

Wildlife has been utilized by humans throughout history and demand continues to grow today. Farming of wildlife can supplement the supply of wild-harvested wildlife products and, in theory, can reduce pressure on free-ranging populations. However, poached wildlife products frequently enter legal markets where they are fraudulently sold as farmed wildlife products. To effectively close this illegal trade in wild-captured wildlife, there is a need to discriminate wild products from farmed products. Because of the strong market demand for wild-captured frog meat and the resulting strong downward pressure on wild populations, we undertook research to develop a method to discriminate wild from farmed Dybowski's frog (Rana dybowskii) based on femur bone density. We measured femur bone density (D(f)) as the ratio of bone mass to bone volume. D(f) of wild frogs revealed a slightly increasing linear trend with increasing age (R(2)=0.214 in males and R(2)=0.111 in females, p=0.000). Wild males and wild females of age classes from 2 to ≥ 5 years had similar D(f) values. In contrast, 2-year-old farmed frogs showed significantly higher D(f) values (p=0.000) among males (mean D(f)=0.623 ± 0.011 g/ml, n=32) than females (mean D(f)=0.558 ± 0.011 g/ml, n=27). For both sexes, D(f) of wild frogs was significantly higher than that of farmed frogs (p=0.000). Among males, 87.5% (28 of 32 individuals) of farmed frogs were correctly identified as farmed frogs and 86.3% (69 of 80 individuals) of wild frogs were correctly identified as wild frogs. These results suggest that femur bone density is one reliable tool for discriminating between wild and farmed Dybowski's frog. This study also highlights a novel strategy with explicit forensic potential to discriminate wild from captive bred wildlife species. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

The Sex Chromosomes of Frogs: Variability and Tolerance Offer Clues to Genome Evolution and Function

PubMed Central

Malcom, Jacob W.; Kudra, Randal S.; Malone, John H.

2014-01-01

Frog sex chromosomes offer an ideal system for advancing our understanding of genome evolution and function because of the variety of sex determination systems in the group, the diversity of sex chromosome maturation states, the ease of experimental manipulation during early development. After briefly reviewing sex chromosome biology generally, we focus on what is known about frog sex determination, sex chromosome evolution, and recent, genomics-facilitated advances in the field. In closing we highlight gaps in our current knowledge of frog sex chromosomes, and suggest priorities for future research that can advance broad knowledge of gene dose and sex chromosome evolution. PMID:25031658

Effects of temperature and hydric environment on survival of the Panamanian Golden Frog infected with a pathogenic chytrid fungus.

PubMed

Bustamante, Heidi M; Livo, Lauren J; Carey, Cynthia

2010-06-01

Considerable controversy exists concerning whether or not climate changes (particularly global warming) are causing outbreaks of a lethal amphibian pathogen, the chytrid fungus Batrachochytrium dendrobatidis (Longcore, Pessier & D.K. Nichols 1999). In the present study, groups of Panamanian golden frogs (Atelopus zeteki Dunn, 1993), a critically endangered amphibian thought to be nearly extinct in Panama, were exposed to varying dosages of zoospores of Batrachochytrium dendrobatidis, temperatures and hydric environments in order to learn whether this species is susceptible to this pathogen and, if so, how environmental factors affect survival. This pathogen proved to be highly lethal for A. zeteki. Frogs exposed to a dosage of 100 Bd zoospores survived significantly (P<0.0001) longer than those that had been exposed to 10(4) or 10(6) zoospores. Exposed frogs housed at 23 °C survived significantly (P<0.0001) longer than those that were housed at 17 °C. Exposed frogs held in dry conditions survived significantly longer than those in wet conditions (P<0.0001). As a laboratory study, these results do not directly test hypotheses about the relation between climate change and the decline of these frogs in the field, but they inform the discussion about how environmental conditions can have an impact on the interaction between a susceptible amphibian and this pathogen. These data do not support the contention that rising global temperatures are necessary to cause the death of amphibians infected with this pathogen because the pathogen was equally lethal at 17 as at 23 °C, and frogs at the warmer temperature lived significantly longer than those at the cooler one. © 2010 ISZS, Blackwell Publishing and IOZ/CAS.

Behavioural adaptations of Rana temporaria to cold climates.

PubMed

Ludwig, Gerda; Sinsch, Ulrich; Pelster, Bernd

2015-01-01

Environmental conditions at the edge of a species' ecological optimum can exert great ecological or evolutionary pressure at local populations. For ectotherms like amphibians temperature is one of the most important abiotic factors of their environment as it influences directly their metabolism and sets limits to their distribution. Amphibians have evolved three ways to cope with sub-zero temperatures: freeze tolerance, freeze protection, freeze avoidance. The aim of this study was to assess which strategy common frogs at mid and high elevation use to survive and thrive in cold climates. In particular we (1) tested for the presence of physiological freeze protection, (2) evaluated autumnal activity and overwintering behaviour with respect to freeze avoidance and (3) assessed the importance of different high-elevation microhabitats for behavioural thermoregulation. Common frogs did not exhibit any signs of freeze protection when experiencing temperatures around 0 °C. Instead they retreated to open water for protection and overwintering. High elevation common frogs remained active for around the same period of time than their conspecifics at lower elevation. Our results suggest that at mid and high elevation common frogs use freeze avoidance alone to survive temperatures below 0 °C. The availability of warm microhabitats, such as rock or pasture, provides high elevation frogs with the opportunity of behavioural thermoregulation and thus allows them to remain active at temperatures at which common frogs at lower elevation cease activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Placement of intracoelomic radio transmitters and silicone passive sampling devices in northern leopard frogs (Lithobates pipiens)

USGS Publications Warehouse

Yaw, Taylor; Swanson, Jennifer E; Pierce, Clay; Muths, Erin L.; Smalling, Kelly; Vandever, Mark; Zaffarano, Bianca Anne

2017-01-01

Historically, wetland toxin exposure studies have relied on single time point samples from stationary sampling devices. Development of passive sampling devices (PSDs) that can be attached to individual animals within wetland habitats has greatly improved in recent years, presenting an innovative sampling technology that can potentially yield individual-specific, quantifiable data about chemical exposure. In this study, silicone based PSDs were attached to the ventral skin of 20 northern leopard frogs (Lithobates pipiens) with polypropylene sutures after radio transmitters had been surgically implanted into the coleomic cavity. After a recovery period frogs were released back into the wetland habitat where they were acquired. The animals were located daily using radio telemetry to assess how long PSDs would remain attached in the frogs' natural habitat. After one week, PSDs remained on 18 of the original 20 frogs. At 2 weeks 17 frogs were recovered and no PSDs remained attached. Although valuable data can be obtained over a short time period, more research will be necessary to demonstrate effectiveness of externally attaching silicone PSDs to northern leopard frogs for time periods longer than 1-2 weeks.

Phase Reconstruction from FROG Using Genetic Algorithms[Frequency-Resolved Optical Gating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Omenetto, F.G.; Nicholson, J.W.; Funk, D.J.

1999-04-12

The authors describe a new technique for obtaining the phase and electric field from FROG measurements using genetic algorithms. Frequency-Resolved Optical Gating (FROG) has gained prominence as a technique for characterizing ultrashort pulses. FROG consists of a spectrally resolved autocorrelation of the pulse to be measured. Typically a combination of iterative algorithms is used, applying constraints from experimental data, and alternating between the time and frequency domain, in order to retrieve an optical pulse. The authors have developed a new approach to retrieving the intensity and phase from FROG data using a genetic algorithm (GA). A GA is a generalmore » parallel search technique that operates on a population of potential solutions simultaneously. Operators in a genetic algorithm, such as crossover, selection, and mutation are based on ideas taken from evolution.« less

Size-sex variation in survival rates and abundance of pig frogs, Rana grylio, in northern Florida wetlands

USGS Publications Warehouse

Wood, K.V.; Nichols, J.D.; Percival, H.F.; Hines, J.E.

1998-01-01

During 1991-1993, we conducted capture-recapture studies on pig frogs, Rana grylio, in seven study locations in northcentral Florida. Resulting data were used to test hypotheses about variation in survival probability over different size-sex classes of pig frogs. We developed multistate capture-recapture models for the resulting data and used them to estimate survival rates and frog abundance. Tests provided strong evidence of survival differences among size-sex classes, with adult females showing the highest survival probabilities. Adult males and juvenile frogs had lower survival rates that were similar to each other. Adult females were more abundant than adult males in most locations at most sampling occasions. We recommended probabilistic capture-recapture models in general, and multistate models in particular, for robust estimation of demographic parameters in amphibian populations.

NASA Ames Summer High School Apprenticeship Research Program

DTIC Science & Technology

1988-09-01

microorganisms, or by producing mutant bacteria and new breeds, interfering with the original destiny of Jovian evolution. And how would we know, many years...Spacelab mission, Spacelab Japan (SL-J), frog embryos will be fertilized in space in the frog embryology unit (FEU--fig. 3). Knowledge of embryology in...limited to animal embryos that develop quickly, which is necessary in a seven-to-ten-day shuttle flight. The rapid dovelopment of frog embryos makes

Diversification in a biodiversity hotspot--the evolution of Southeast Asian rhacophorid tree frogs on Borneo (Amphibia: Anura: Rhacophoridae).

PubMed

Hertwig, Stefan T; Schweizer, Manuel; Das, Indraneil; Haas, Alexander

2013-09-01

The tree-frog family Rhacophoridae is a major group contributing to the high pecies richness and reproductive diversity among vertebrates of Sundaland. Nonetheless, rhacophorid evolution, specially on Borneo, has not been studied within a phylogenetic context. In this study, we examine the phylogenetic relationships of 38 (out of 41) Bornean species of Rhacophoridae, in combination with data from previous phylogenetic studies. In the final super matrix of 91 species, we analyse sequence data from two mitochondrial and three nuclear genes. The resulting trees show the genus Rhacophorus as a paraphyletic assemblage. As a consequence, we transfer Rhacophorus appendiculatus and R. kajau to two other genera and propose the new phylogeny-based combinations--Kurixalus appendiculatus and Feihyla kajau, respectively. Furthermore, we use our phylogenetic hypotheses to reconstruct the evolution of reproductive modes in rhacophorid tree frogs. Direct development to the exclusion of a free larval stage evolved twice independently, once in an ancestor of the Pseudophilautus+Raorchestes clade in India and Sri Lanka, and once within Philautus in Southeast Asia. The deposition of egg clutches covered by a layer of jelly in Feihyla is also present in F. kajau and thus confirms our generic reassignment. The remarkably high diversity of rhacophorid tree frogs on Borneo is the outcome of a complex pattern of repeated vicariance and dispersal events caused by past changes in the climatic and geological history of the Sunda shelf. We identified geographic clades of closely related endemic species within Rhacophorus and Philautus, which result from local island radiations on Borneo. Copyright © 2013 Elsevier Inc. All rights reserved.

Estimates of DNA damage by the comet assay in the direct-developing frog Eleutherodactylus johnstonei (Anura, Eleutherodactylidae)

PubMed Central

Valencia, Laura Carolina; García, Adriana; Ramírez-Pinilla, Martha Patricia; Fuentes, Jorge Luis

2011-01-01

The aim of this study was to use the Comet assay to assess genetic damage in the direct-developing frog Eleutherodactylus johnstonei. A DNA diffusion assay was used to evaluate the effectiveness of alkaline, enzymatic and alkaline/enzymatic treatments for lysing E. johnstonei blood cells and to determine the amount of DNA strand breakage associated with apoptosis and necrosis. Cell sensitivity to the mutagens bleomycin (BLM) and 4-nitro-quinoline-1-oxide (4NQO) was also assessed using the Comet assay, as was the assay reproducibility. Alkaline treatment did not lyse the cytoplasmic and nuclear membranes of E. johnstonei blood cells, whereas enzymatic digestion with proteinase K (40 μg/mL) yielded naked nuclei. The contribution of apoptosis and necrosis (assessed by the DNA diffusion assay) to DNA damage was estimated to range from 0% to 8%. BLM and 4NQO induced DNA damage in E. johnstonei blood cells at different concentrations and exposure times. Dose-effect curves with both mutagens were highly reproducible and showed consistently low coefficients of variation (CV ≤ 10%). The results are discussed with regard to the potential use of the modified Comet assay for assessing the exposure of E. johnstonei to herbicides in ecotoxicological studies. PMID:22215974

Estimates of DNA damage by the comet assay in the direct-developing frog Eleutherodactylus johnstonei (Anura, Eleutherodactylidae).

PubMed

Valencia, Laura Carolina; García, Adriana; Ramírez-Pinilla, Martha Patricia; Fuentes, Jorge Luis

2011-10-01

The aim of this study was to use the Comet assay to assess genetic damage in the direct-developing frog Eleutherodactylus johnstonei. A DNA diffusion assay was used to evaluate the effectiveness of alkaline, enzymatic and alkaline/enzymatic treatments for lysing E. johnstonei blood cells and to determine the amount of DNA strand breakage associated with apoptosis and necrosis. Cell sensitivity to the mutagens bleomycin (BLM) and 4-nitro-quinoline-1-oxide (4NQO) was also assessed using the Comet assay, as was the assay reproducibility. Alkaline treatment did not lyse the cytoplasmic and nuclear membranes of E. johnstonei blood cells, whereas enzymatic digestion with proteinase K (40 μg/mL) yielded naked nuclei. The contribution of apoptosis and necrosis (assessed by the DNA diffusion assay) to DNA damage was estimated to range from 0% to 8%. BLM and 4NQO induced DNA damage in E. johnstonei blood cells at different concentrations and exposure times. Dose-effect curves with both mutagens were highly reproducible and showed consistently low coefficients of variation (CV ≤ 10%). The results are discussed with regard to the potential use of the modified Comet assay for assessing the exposure of E. johnstonei to herbicides in ecotoxicological studies.

Pseudacris triseriata (western chorus frog) and Rana sylvatica (wood frog) chytridiomycosis

USGS Publications Warehouse

Rittman, S.E.; Muths, E.; Green, D.E.

2003-01-01

The chytrid fungus Batrachochytrium dendrobatidis is a known pathogen of anuran amphibians, and has been correlated with amphibian die-offs worldwide (Daszak et. al. 1999. Emerging Infectious Diseases 5:735-748). In Colorado, B. dendrobatidis has infected Boreal toads (Bufo boreas) (Muths et. al., in review) and has been identified on museum specimens of northern leopard frogs (Rana pipiens) (Carey et. al. 1999. Develop. Comp. Immunol. 23:459-472). We report the first verified case of chytrid fungus in chorus frogs (Pseudacris triseriata) and wood frogs (Rana sylvatica) in the United States. We collected seven P. triseriata, and two adult and two juvenile R. sylvatica in the Kawuneeche Valley in Rocky Mountain National Park (RMNP) during June 2001. These animals were submitted to the National Wildlife Health Center (NWHC) as part of an amphibian health evaluation in RMNP. Chorus frogs were shipped in one container. Wood frog adults and juveniles were shipped in two separate containers. Histological examinations of all chorus frogs and 3 of 4 wood frogs were positive for chytrid fungus infection. The fourth (adult) wood frog was too decomposed for meaningful histology. Histological findings consisted of multifocally mild to diffusely severe infections of the epidermis of the ventrum and hindlimb digital skin. Chytrid thalli were confined to the thickened epidermis (hyperkeratosis), were spherical to oval, and occasional thalli contained characteristic discharge pores or zoospores (Green and Kagarise Sherman 1999. J. Herpetol 35:92-103; Fellers et al. 2001. Copeia 2001:945-953). We cannot confirm that all specimens carried the fungus at collection, because infection may have spread from one individual to all other individuals in each container during transport. Further sampling of amphibians in Kawuneeche Valley is warranted to determine the rate of infection and mortality in these populations.

Clinal patterns in genetic variation for northern leopard frog (Rana pipiens): Conservation status and population histories

USGS Publications Warehouse

Stockwell, Craig A.; Fisher, Justin D.L.; McLean, Kyle I.

2016-01-01

The security of the northern leopard frog (Rana pipiens) varies spatially with populations east and west of North Dakota considered as secure and at risk, respectively. We used genetic markers to characterize the conservation status of northern leopard frog populations across North Dakota. We used multiple regression analyses and model selection to evaluate correlations of expected heterozygosity (HE) with the direct and additive effects of: i) geographic location,ii) wetland density and iii) average annual precipitation. There was lower genetic diversity in the western portion of the state due to lower levels of diversity for populations southwest of the Missouri River. This may reflect a refugial/colonization signature for the only non-glaciated area of North Dakota. Genetic diversity was also positively associated with wetland densities which is consistent with the reliance of this species on a mosaic of wetlands. Our findings suggest that populations in the southwestern part of North Dakota are of higher conservation concern, a finding consistent with the higher risk noted for northern leopard frog populations in most states west of North Dakota. Our findings also pose the hypothesis that climate change induced changes in wetland densities will reduce genetic diversity of northern leopard frog populations.

The trade-off between maturation and growth during accelerated development in frogs.

PubMed

Mueller, Casey A; Augustine, Starrlight; Kooijman, Sebastiaan A L M; Kearney, Michael R; Seymour, Roger S

2012-09-01

Developmental energetics are crucial to a species' life history and ecology but are poorly understood from a mechanistic perspective. Traditional energy and mass budgeting does not distinguish between costs of growth and maturation, making it difficult to account for accelerated development. We apply a metabolic theory that uniquely considers maturation costs (Dynamic Energy Budget theory, DEB) to interpret empirical data on the energetics of accelerated development in amphibians. We measured energy use until metamorphosis in two related frogs, Crinia georgiana and Pseudophryne bibronii. Mass and energy content of fresh ova were comparable between the species. However, development to metamorphosis was 1.7 times faster in C. georgiana while P. bibronii produced nine times the dry biomass at metamorphosis and had lower mass-specific oxygen requirements. DEB theory explained these patterns through differences in ontogenetic energy allocation to maturation. P. bibronii partitioned energy in the same (constant) way throughout development whereas C. georgiana increased the fraction of energy allocated to maturation over growth between hatching and the onset of feeding. DEB parameter estimation for additional, direct-developing taxa suggests that a change in energy allocation during development may result from a selective pressure to increase development rate, and not as a result of development mode. Published by Elsevier Inc.

Surveys for presence of Oregon spotted frog (Rana pretiosa): background information and field methods

USGS Publications Warehouse

Pearl, Christopher A.; Clayton, David; Turner, Lauri

2010-01-01

The Oregon spotted frog (Rana pretiosa) is the most aquatic of the native frogs in the Pacific Northwest. The common name derives from the pattern of black, ragged-edged spots set against a brown or red ground color on the dorsum of adult frogs. Oregon spotted frogs are generally associated with wetland complexes that have several aquatic habitat types and sizeable coverage of emergent vegetation. Like other ranid frogs native to the Northwest, Oregon spotted frogs breed in spring, larvae transform in summer of their breeding year, and adults tend to be relatively short lived (3-5 yrs). Each life stage (egg, tadpole, juvenile and adult) has characteristics that present challenges for detection. Breeding can be explosive and completed within 1-2 weeks. Egg masses are laid in aggregations, often in a few locations in large areas of potential habitat. Egg masses can develop, hatch, and disintegrate in <2 weeks during warm weather. Tadpoles can be difficult to identify, have low survival, and spend most of their 3-4 months hidden in vegetation or flocculant substrates. Juveniles and adults are often difficult to capture and can spend summers away from breeding areas. Moreover, a substantial portion of extant populations are of limited size (<100 breeding adults), and field densities of all life stages are often low. An understanding of the biology of the species and use of multiple visits are thus important for assessing presence of Oregon spotted frogs. This report is meant to be a resource for USDA Region 6 Forest Service (FS) and OR/WA Bureau of Land Management (BLM) personnel tasked with surveying for the presence of Oregon spotted frogs. Our objective was to summarize information to improve the efficiency of field surveys and increase chances of detection if frogs are present. We include overviews of historical and extant ranges of Oregon spotted frog. We briefly summarize what is known of Oregon spotted frog habitat associations and review aspects of behavior and ecology that are likely to affect detectability in the field. We summarize characteristics that can help differentiate Oregon spotted frog life stages from other northwestern ranid frogs encountered during surveys. Appendices include examples of data collection formats and a protocol for disinfecting field gear.

More similar than you think: Frog metamorphosis as a model of human perinatal endocrinology.

PubMed

Buchholz, Daniel R

2015-12-15

Hormonal control of development during the human perinatal period is critically important and complex with multiple hormones regulating fetal growth, brain development, and organ maturation in preparation for birth. Genetic and environmental perturbations of such hormonal control may cause irreversible morphological and physiological impairments and may also predispose individuals to diseases of adulthood, including diabetes and cardiovascular disease. Endocrine and molecular mechanisms that regulate perinatal development and that underlie the connections between early life events and adult diseases are not well elucidated. Such mechanisms are difficult to study in uterus-enclosed mammalian embryos because of confounding maternal effects. To elucidate mechanisms of developmental endocrinology in the perinatal period, Xenopus laevis the African clawed frog is a valuable vertebrate model. Frogs and humans have identical hormones which peak at birth and metamorphosis, have conserved hormone receptors and mechanisms of gene regulation, and have comparable roles for hormones in many target organs. Study of molecular and endocrine mechanisms of hormone-dependent development in frogs is advantageous because an extended free-living larval period followed by metamorphosis (1) is independent of maternal endocrine influence, (2) exhibits dramatic yet conserved developmental effects induced by thyroid and glucocorticoid hormones, and (3) begins at a developmental stage with naturally undetectable hormone levels, thereby facilitating endocrine manipulation and interpretation of results. This review highlights the utility of frog metamorphosis to elucidate molecular and endocrine actions, hormone interactions, and endocrine disruption, especially with respect to thyroid hormone. Knowledge from the frog model is expected to provide fundamental insights to aid medical understanding of endocrine disease, stress, and endocrine disruption affecting the perinatal period in humans. Copyright © 2015 Elsevier Inc. All rights reserved.

Games With a Purpose: Frog and the Lily Pads

ERIC Educational Resources Information Center

Sawicki, Timothy

2005-01-01

This article describes a game involving poly spots, frog bean bags, and a basket that can be used to assess locomotor activities, e.g., hopping and throwing, while also developing teamwork strategies and mathematical abilities.

Hind limb malformations in free-living northern leopard frogs (Rana pipiens) from Maine, Minnesota, and Vermont suggest multiple etiologies

USGS Publications Warehouse

Meteyer, C.U.; Loeffler, I.K.; Fallon, J.F.; Converse, K.A.; Green, E.; Helgen, J.C.; Kersten, S.; Levey, R.; Eaton-Poole, L.; Burkhart, J.G.

2000-01-01

Background Reports of malformed frogs have increased throughout the North American continent in recent years. Most of the observed malformations have involved the hind limbs. The goal of this study was to accurately characterize the hind limb malformations in wild frogs as an important step toward understanding the possible etiologies. Methods During 1997 and 1998, 182 recently metamorphosed northern leopard frogs (Rana pipiens) were collected from Minnesota, Vermont, and Maine. Malformed hind limbs were present in 157 (86%) of these frogs, which underwent necropsy and radiographic evaluation at the National Wildlife Health Center. These malformations are described in detail and classified into four major categories: (1) no limb (amelia); (2) multiple limbs or limb elements (polymelia, polydactyly, polyphalangy); (3) reduced limb segments or elements (phocomelia, ectromelia, ectrodactyly, and brachydactyly; and (4) distally complete but malformed limb (bone rotations, bridging, skin webbing, and micromelia). Results Amelia and reduced segments and/or elements were the most common finding. Frogs with bilateral hind limb malformations were not common, and in only eight of these 22 frogs were the malformations symmetrical. Malformations of a given type tended to occur in frogs collected from the same site, but the types of malformations varied widely among all three states, and between study sites within Minnesota. Conclusions Clustering of malformation type suggests that developmental events may produce a variety of phenotypes depending on the timing, sequence, and severity of the environmental insult. Hind limb malformations in free-living frogs transcend current mechanistic explanations of tetrapod limb development.

Distribution and postbreeding environmental relationships of Northern leopard frogs (Rana [Lithobates] pipiens) in Washington

USGS Publications Warehouse

Germaine, S.S.; Hays, D.W.

2009-01-01

Northern leopard frogs (Rana [Lithobates] pipiens) are considered sensitive, threatened, or endangered in all western states and western Canadian provinces. Historically present in eastern Washington in 6 major river drainages, leopard frogs are now only known to occur at 2 localized areas in the Crab Creek drainage in Grant County. During the summers of 2002-2005, we surveyed both areas to document extent of leopard frog distributions and to describe habitat and vertebrate community characteristics associated with leopard frog site occupancy. At Gloyd Seeps, 2 juvenile leopard frogs were observed in a total of 8.2 person-days of searching along a 5-km stream reach. At Potholes Reservoir, we surveyed 243 wetland sites in 7 management units known to have been occupied by leopard frogs during the 1980s. We confirmed leopard frog presence at only 87 sites (36%) in 4 management units. Site occupancy models for individual ponds indicated that, compared to unoccupied sites, occupied sites had slightly greater pond depths, less tall emergent vegetation, more herbaceous vegetative cover, and fewer neighboring ponds containing nonnative predatory fish. Models developed at the 1-km2 scale indicated that occupied areas had greater average midsummer pond depths, fewer ponds occupied by bullfrogs (Rana [Lithobates] catesbeiana) and carp (Cyprinus carpio), and more herbaceous vegetation surrounding ponds. The Gloyd Seeps population now appears defunct, and the Potholes Reservoir population is in sharp decline. Unless management actions are taken to reduce nonnative fish and bullfrogs and to enhance wetland vegetation, leopard frogs may soon be extirpated from both sites and possibly, therefore, from Washington.

A model for the interaction of frog population dynamics with Batrachochytrium dendrobaties, Janthinobacterium lividium and temperature and its implication for chytridiomycosis management

USGS Publications Warehouse

Ackleh, Azmy S.; Carter, Jacoby; Chellamuthu, Vinodh K.; Ma, Baoling

2016-01-01

Chytridiomycosis is an emerging disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) that poses a serious threat to frog populations worldwide. Several studies have shown that inoculation of bacterial species Janthinobacterium lividum (Jl) can mitigate the impact of the disease. However, there are many questions regarding this interaction. A mathematical model of a frog population infected with chytridiomycosis is developed to investigate how the inoculation of Jl could reduce the impact of Bd disease on frogs. The model also illustrates the important role of temperature in disease dynamics. The model simulation results suggest possible control strategies for Jl to limit the impact of Bd in various scenarios. However, a better knowledge of Jl life cycle is needed to fully understand the interaction of Jl, Bd, temperature and frogs.

Multi-Scale, Direct and Indirect Effects of the Urban Stream Syndrome on Amphibian Communities in Streams

PubMed Central

Canessa, Stefano; Parris, Kirsten M.

2013-01-01

Urbanization affects streams by modifying hydrology, increasing pollution and disrupting in-stream and riparian conditions, leading to negative responses by biotic communities. Given the global trend of increasing urbanization, improved understanding of its direct and indirect effects at multiple scales is needed to assist management. The theory of stream ecology suggests that the riverscape and the surrounding landscape are inextricably linked, and watershed-scale processes will also affect in-stream conditions and communities. This is particularly true for species with semi-aquatic life cycles, such as amphibians, which transfer energy between streams and surrounding terrestrial areas. We related measures of urbanization at different scales to frog communities in streams along an urbanization gradient in Melbourne, Australia. We used boosted regression trees to determine the importance of predictors and the shape of species responses. We then used structural equation models to investigate possible indirect effects of watershed imperviousness on in-stream parameters. The proportion of riparian vegetation and road density surrounding the site at the reach scale (500-m radius) had positive and negative effects, respectively, on species richness and on the occurrence of the two most common species in the area ( Crinia signifera and Limnodynastesdumerilii ). Road density and local aquatic vegetation interacted in influencing species richness, suggesting that isolation of a site can prevent colonization, in spite of apparently good local habitat. Attenuated imperviousness at the catchment scale had a negative effect on local aquatic vegetation, indicating possible indirect effects on frog species not revealed by single-level models. Processes at the landscape scale, particularly related to individual ranging distances, can affect frog species directly and indirectly. Catchment imperviousness might not affect adult frogs directly, but by modifying hydrology it can disrupt local vegetation and prove indirectly detrimental. Integrating multiple-scale management actions may help to meet conservation targets for streams in the face of urbanization. PMID:23922963

Distinguishing synchronous and time-varying synergies using point process interval statistics: motor primitives in frog and rat

PubMed Central

Hart, Corey B.; Giszter, Simon F.

2013-01-01

We present and apply a method that uses point process statistics to discriminate the forms of synergies in motor pattern data, prior to explicit synergy extraction. The method uses electromyogram (EMG) pulse peak timing or onset timing. Peak timing is preferable in complex patterns where pulse onsets may be overlapping. An interval statistic derived from the point processes of EMG peak timings distinguishes time-varying synergies from synchronous synergies (SS). Model data shows that the statistic is robust for most conditions. Its application to both frog hindlimb EMG and rat locomotion hindlimb EMG show data from these preparations is clearly most consistent with synchronous synergy models (p < 0.001). Additional direct tests of pulse and interval relations in frog data further bolster the support for synchronous synergy mechanisms in these data. Our method and analyses support separated control of rhythm and pattern of motor primitives, with the low level execution primitives comprising pulsed SS in both frog and rat, and both episodic and rhythmic behaviors. PMID:23675341

Alternative life cycle strategies in the West African reed frog Hyperolius nitidulus: the answer to an unpredictable environment?

PubMed

Lampert, Kathrin P; Linsenmair, Eduard K

2002-02-01

The West African reed frog Hyperolius nitidulus, mainly known for its extraordinary aestivation behaviour and physiology, is able to vary its reproductive strategy in response to environmental conditions. We found indirect as well as direct evidence for individuals not following the generally assumed one year-one generation life cycle including an extended aestivation phase during the dry season, but leading very short lives for only a part of that rainy season in which the frogs were born. Second-generation frogs (males and females that reproduced in the season in which they were born) were significantly smaller than all other adults and their egg diameter was reduced. As the pattern and amount of rainfall and thus the span of time suitable for reproduction in H. nitidulus varies strongly between years in this savannah region, a flexible reproductive strategy may be highly adaptive for risk spreading. Alternative reproduction strategies probably contribute to the great success of H. nitidulus in terms of the extension of its geographical range and its often very high local abundance.

Hematophagous insects as vectors for frog trypanosomes.

PubMed

Ramos, B; Urdaneta-Morales, S

1977-12-01

Experimental infections of three hematophagous arthropods (Rhodnius prolixus, Aedes aegypti, and Culex pipiens) with a trypanosome of the Trypanosoma rotatorium complex found in the frogs Hyla crepitans and Leptodactylus insularum revealed that A. aegypti is a good host for the flagellate; the course of development in the intestinal tract of the mosquito is described from 15 minutes to 168 hours. C. pipiens showed only low intestinal infections and R. prolixus did not permit development of the parasite. It is postulated that, in addition to the transmission of T. rotatorium by leeches, batrachophilic mosquitoes may transmit the parasite to frogs of more terrestrial habits by being ingested by these anurans.

Function of the two Xenopus smad4s in early frog development.

PubMed

Chang, Chenbei; Brivanlou, Ali H; Harland, Richard M

2006-10-13

Signals from the transforming growth factor beta family members are transmitted in the cell through specific receptor-activated Smads and a common partner Smad4. Two Smad4 genes (alpha and beta/10, or smad4 and smad4.2) have been isolated from Xenopus, and conflicting data are reported for Smad4beta/10 actions in mesodermal and neural induction. To further understand the functions of the Smad4s in early frog development, we analyzed their activities in detail. We report that Smad10 is a mutant form of Smad4beta that harbors a missense mutation of a conserved arginine to histidine in the MH1 domain. The mutation results in enhanced association of Smad10 with the nuclear transcription corepressor Ski and leads to its neural inducing activity through inhibition of bone morphogenetic protein (BMP) signaling. In contrast to Smad10, both Smad4alpha and Smad4beta enhanced BMP signals in ectodermal explants. Using antisense morpholino oligonucleotides (MOs) to knockdown endogenous Smad4 protein levels, we discovered that Smad4beta was required for both activin- and BMP-mediated mesodermal induction in animal caps, whereas Smad4alpha affected only the BMP signals. Neither Smad4 was involved directly in neural induction. Expression of Smad4beta-MO in early frog embryos resulted in reduction of mesodermal markers and defects in axial structures, which were rescued by either Smad4alpha or Smad4beta. Smad4alpha-MO induced only minor deficiency at late stages. As Smad4beta, but not Smad4alpha, is expressed at high levels maternally and during early gastrulation, our data suggest that although Smad4alpha and Smad4beta may have similar activities, they are differentially utilized during frog embryogenesis, with only Smad4beta being essential for mesoderm induction.

Effects of the herbicide imazapyr on juvenile Oregon spotted frogs

USGS Publications Warehouse

Yahnke, Amy E.; Grue, Christian E.; Hayes, Marc P.; Troiano, Alexandra T.

2013-01-01

Conflict between native amphibians and aquatic weed management in the Pacific Northwest is rarely recognized because most native stillwater-breeding amphibian species move upland during summer, when herbicide application to control weeds in aquatic habitats typically occurs. However, aquatic weed management may pose a risk for aquatic species present in wetlands through the summer, such as the Oregon spotted frog (OSF, Rana pretiosa), a state endangered species in Washington. Acute toxicity of herbicides used to control aquatic weeds tends to be low, but the direct effects of herbicide tank mixes on OSFs have remained unexamined. We exposed juvenile OSFs to tank mixes of the herbicide imazapyr, a surfactant, and a marker dye in a 96-h static-renewal test. The tank mix was chosen because of its low toxicity to fish and its effectiveness in aquatic weed control. Concentrations were those associated with low-volume (3.5 L/ha) and high-volume (7.0 L/ha) applications of imazapyr and a clean-water control. Following exposure, frogs were reared for two months in clean water to identify potential latent effects on growth. Endpoints evaluated included feeding behavior, growth, and body and liver condition indices. We recorded no mortalities and found no significant differences for any end point between the herbicide-exposed and clean-water control frogs. The results suggest that imazapyr use in wetland restoration poses a low risk of direct toxic effects on juvenile OSFs.

Hyperspectral analysis of columbia spotted frog habitat

USGS Publications Warehouse

Shive, J.P.; Pilliod, D.S.; Peterson, C.R.

2010-01-01

Wildlife managers increasingly are using remotely sensed imagery to improve habitat delineations and sampling strategies. Advances in remote sensing technology, such as hyperspectral imagery, provide more information than previously was available with multispectral sensors. We evaluated accuracy of high-resolution hyperspectral image classifications to identify wetlands and wetland habitat features important for Columbia spotted frogs (Rana luteiventris) and compared the results to multispectral image classification and United States Geological Survey topographic maps. The study area spanned 3 lake basins in the Salmon River Mountains, Idaho, USA. Hyperspectral data were collected with an airborne sensor on 30 June 2002 and on 8 July 2006. A 12-year comprehensive ground survey of the study area for Columbia spotted frog reproduction served as validation for image classifications. Hyperspectral image classification accuracy of wetlands was high, with a producer's accuracy of 96 (44 wetlands) correctly classified with the 2002 data and 89 (41 wetlands) correctly classified with the 2006 data. We applied habitat-based rules to delineate breeding habitat from other wetlands, and successfully predicted 74 (14 wetlands) of known breeding wetlands for the Columbia spotted frog. Emergent sedge microhabitat classification showed promise for directly predicting Columbia spotted frog egg mass locations within a wetland by correctly identifying 72 (23 of 32) of known locations. Our study indicates hyperspectral imagery can be an effective tool for mapping spotted frog breeding habitat in the selected mountain basins. We conclude that this technique has potential for improving site selection for inventory and monitoring programs conducted across similar wetland habitat and can be a useful tool for delineating wildlife habitats. ?? 2010 The Wildlife Society.

Enzymatic regulation of seasonal glycogen cycling in the freeze-tolerant wood frog, Rana sylvatica.

PubMed

do Amaral, M Clara F; Lee, Richard E; Costanzo, Jon P

2016-12-01

Liver glycogen is an important energy store in vertebrates, and in the freeze-tolerant wood frog, Rana sylvatica, this carbohydrate also serves as a major source of the cryoprotectant glucose. We investigated how variation in the levels of the catalytic subunit of protein kinase A (PKAc), glycogen phosphorylase (GP), and glycogen synthase (GS) relates to seasonal glycogen cycling in a temperate (Ohioan) and subarctic (Alaskan) populations of this species. In spring, Ohioan frogs had reduced potential for glycogen synthesis, as evidenced by low GS activity and high PKAc protein levels. In addition, glycogen levels in spring were the lowest of four seasonal samples, as energy input was likely directed towards metabolism and somatic growth during this period. Near-maximal glycogen levels were reached by mid-summer, and remained unchanged in fall and winter, suggesting that glycogenesis was curtailed during this period. Ohioan frogs had a high potential for glycogenolysis and glycogenesis in winter, as evidenced by large glycogen reserves, high levels of GP and GS proteins, and high GS activity, which likely allows for rapid mobilization of cryoprotectant during freezing and replenishing of glycogen reserves during thawing. Alaskan frogs also achieved a near-maximal liver glycogen concentration by summer and displayed high glycogenic and glycogenolytic potential in winter, but, unlike Ohioan frogs, started replenishing their energy reserves early in spring. We conclude that variation in levels of both glycogenolytic and glycogenic enzymes likely happens in response to seasonal changes in energetic strategies and demands, with winter survival being a key component to understanding the regulation of glycogen cycling in this species.

Effects of water temperature on breeding phenology, growth and timing of metamorphosis of foothill yellow-legged frogs (Rana boylii) on the mainstem and selected tributaries of California's Trinity River - 2004-2009.

Treesearch

Clara Wheeler; James Bettaso; Donald Ashton; Hartwell Welsh

2013-01-01

The cold temperatures maintained in the Trinity River are beneficial to fish but may be problematic for foothill yellow-legged frogs. We examined the timing of breeding, reproductive output, and growth and development of tadpoles for populations of foothill yellow-legged frogs on the mainstem and six tributaries of the Trinity River. On the colder mainstem, onset of...

Landscape associations of frog and toad species in Iowa and Wisconsin, U.S.A

USGS Publications Warehouse

Knutson, M.G.; Sauer, J.R.; Olsen, D.A.; Mossman, M.J.; Hemesath, L.M.; Lannoo, M.J.; Kaiser, Hinrich; Casper, Gary S.; Bernstein, Neil P.

2000-01-01

Landscape habitat associations of frogs and toads in Iowa and Wisconsin were tested to determine whether they support or refute previous general habitat classifications. We examined which Midwestern species shared similar habitats to see if these associations were consistent across large geographic areas (states). Rana sylvatica (wood frog), Hyla versicolor (eastern gray treefrog), Pseudacris crucifer (spring peeper), and Acris crepitans (cricket frog) were identified as forest species, P. triseriata (chorus frog), H. chrysoscelis (Cope's gray treefrog), R. pipiens (leopard frog), and Bufo americanus (American toad) as grassland species, and R. catesbeiana (bullfrog), R. clamitans (green frog), R. palustris (pickerel frog), and R. septentrionalis (mink frog) as lake or stream species. The best candidates to serve as bioindicators of habitat quality were the forest species R. sylvatica, H. versicolor, and P. crucifer, the grassland species R. pipiens and P. triseriata, and a cold water wetland species, R. palustris. Declines of P. crucifer, R. pipiens, and R. palustris populations in one or both states may reflect changes in habitat quality. Habitat and community associations of some species differed between states, indicating that these relationships may change across the range of a species. Acris crepitans may have shifted its habitat affinities from open habitats, recorded historically, to the more forested habitat associations we recorded. We suggest contaminants deserve more investigation regarding the abrupt and widespread declines of this species. Interspersion of different habitat types was positively associated with several species. A larger number of wetland patches may increase breeding opportunities and increase the probability of at least one site being suitable. We noted consistently negative associations between anuran species and urban development. Given the current trend of urban growth and increasing density of the human population, declines of amphibian populations are likely to continue.

Cytogenetic characterization and B chromosome diversity in direct-developing frogs of the genus Oreobates (Brachycephaloidea, Craugastoridae)

PubMed Central

Ferro, Juan Martín; Taffarel, Alberto; Cardozo, Darío; Grosso, Jimena; Puig, María Pía; Suárez, Pablo; Akmentins, Mauricio Sebastián; Baldo, Diego

2016-01-01

Abstract Oreobates Jiménez de la Espada, 1872 is a large group of South American frogs with terrestrial reproduction and direct development, located in the superfamily Brachycephaloidea. About 260 brachycephaloidean species have been cytogenetically studied so far, at least with standard techniques. However, this information represents fewer than 17% species of the family Craugastoridae Hedges, Duellman & Heinicke, 2008, where the genus Oreobates is included. In the present work, using a diversity of standard and molecular techniques, we describe the karyotype of Oreobates barituensis Vaira & Ferrari, 2008, Oreobates berdemenos Pereyra, Cardozo, Baldo & Baldo, 2014 and Oreobates discoidalis (Peracca, 1895), from northwestern Argentina. The three species analyzed showed a diploid karyotype with 2n = 22 biarmed chromosomes, fundamental number (FN) = 44, nucleolus organizer regions (NORs) located pericentromerically on pair 7, and a centromeric and pericentromeric C-banding pattern. We observed variations in the chromosome number in Oreobates barituensis due the presence of two morphs of B chromosomes, one medium-sized telocentric (BT) and another subtelocentric and smaller (Bst). Both B chromosomes are mitotically stable and were recorded in all somatic and germinal cells analyzed. The BT chromosome occurred at a maximum of one per individual (2n = 22+BT), and the other one was observed single (2n = 22 + Bst) or as a pair in two doses (2n = 22 + 2BT). We additionally observed other supernumerary chromosomes in the three species analyzed, all of them euchromatic, small, dot-shaped and with instability during mitoses, showing a frequency of occurrence below 50% in studied specimens. The occurrence of polymorphic and spontaneous chromosomal rearrangements and supernumerary chromosomes is a recurrent feature reported in frogs with terrestrial habits (Brachycephaloidea and Hemiphractidae Peters, 1862), which suggests that Brachycephaloidea may be a promising group for studying the origin and maintenance of B chromosomes in anurans. PMID:27186344

Transcription factors Mix1 and VegT, relocalization of vegt mRNA, and conserved endoderm and dorsal specification in frogs

PubMed Central

Sudou, Norihiro; Garcés-Vásconez, Andrés; López-Latorre, María A.; Taira, Masanori

2016-01-01

Protein expression of the transcription factor genes mix1 and vegt characterized the presumptive endoderm in embryos of the frogs Engystomops randi, Epipedobates machalilla, Gastrotheca riobambae, and Eleutherodactylus coqui, as in Xenopus laevis embryos. Protein VegT was detected in the animal hemisphere of the early blastula in all frogs, and only the animal pole was VegT-negative. This finding stimulated a vegt mRNA analysis in X. laevis eggs and embryos. vegt mRNA was detected in the animal region of X. laevis eggs and early embryos, in agreement with the VegT localization observed in the analyzed frogs. Moreover, a dorso-animal relocalization of vegt mRNA occurred in the egg at fertilization. Thus, the comparative analysis indicated that vegt may participate in dorsal development besides its known roles in endoderm development, and germ-layer specification. Zygotic vegt (zvegt) mRNA was detected as a minor isoform besides the major maternal (mvegt) isoform of the X. laevis egg. In addition, α-amanitin–insensitive vegt transcripts were detected around vegetal nuclei of the blastula. Thus, accumulation of vegt mRNA around vegetal nuclei was caused by relocalization rather than new mRNA synthesis. The localization of vegt mRNA around vegetal nuclei may contribute to the identity of vegetal blastomeres. These and previously reportedly localization features of vegt mRNA and protein derive from the master role of vegt in the development of frogs. The comparative analysis indicated that the strategies for endoderm, and dorsal specification, involving vegt and mix1, have been evolutionary conserved in frogs. PMID:27140624

Generation of the Dimensional Embryology Application (App) for Visualization of Early Chick and Frog Embryonic Development

ERIC Educational Resources Information Center

Webb, Rebecca L.; Bilitski, James; Zerbee, Alyssa; Symans, Alexandra; Chop, Alexandra; Seitz, Brianne; Tran, Cindy

2015-01-01

The study of embryonic development of multiple organisms, including model organisms such as frogs and chicks, is included in many undergraduate biology programs, as well as in a variety of graduate programs. As our knowledge of biological systems increases and the amount of material to be taught expands, the time spent instructing students about…

Frogs as integrative models for understanding digestive organ development and evolution

PubMed Central

Womble, Mandy; Pickett, Melissa; Nascone-Yoder, Nanette

2016-01-01

The digestive system comprises numerous cells, tissues and organs that are essential for the proper assimilation of nutrients and energy. Many aspects of digestive organ function are highly conserved among vertebrates, yet the final anatomical configuration of the gut varies widely between species, especially those with different diets. Improved understanding of the complex molecular and cellular events that orchestrate digestive organ development is pertinent to many areas of biology and medicine, including the regeneration or replacement of diseased organs, the etiology of digestive organ birth defects, and the evolution of specialized features of digestive anatomy. In this review, we highlight specific examples of how investigations using Xenopus laevis frog embryos have revealed insight into the molecular and cellular dynamics of digestive organ patterning and morphogenesis that would have been difficult to obtain in other animal models. Additionally, we discuss recent studies of gut development in non-model frog species with unique feeding strategies, such as Lepidobatrachus laev is and Eleutherodactylouscoqui, which are beginning to provide glimpses of the evolutionary mechanisms that may generate morphological variation in the digestive tract. The unparalleled experimental versatility of frog embryos make them excellent, integrative models for studying digestive organ development across multiple disciplines. PMID:26851628

PHENOBARBITAL AFFECTS THYROID HISTOLOGY AND LARVAL DEVELOPMENT IN THE AFRICAN CLAWED FROG XENOPUS LAEVIS

EPA Science Inventory

The abstract highlights our recent study to explore endocrine disrupting effects of phenobarbital in the African clawed frog, Xenopus laevis. In mammals, this chemical is known to induce the biotransforming enzyme UDP-glucuronosyltransferase (UDPGT) resulting in increased thyroid...

Conservation of the introgressed European water frog complex using molecular tools.

PubMed

Holsbeek, G; Maes, G E; De Meester, L; Volckaert, F A M

2009-03-01

In Belgium, the Pelophylax esculentus complex has recently been subjected to multiple introductions of non-native water frogs, increasing the occurrence of hybridisation events. In the present study, we tested the reliability of morphometric and recently developed microsatellite tools to identify introgression and to determine the origin of exotic Belgian water frogs. By analysing 150 individuals of each taxon of the P. esculentus complex and an additional 60 specimens of the introduced P. cf. bedriagae, we show that neither of the currently available tools appears to have sufficient power to reliably distinguish all Belgian water frog species. We therefore aimed at increasing the discriminatory power of a microsatellite identification tool by developing a new marker panel with additional microsatellite loci. By adding only two new microsatellite loci (RlCA5 and RlCA1b20), all taxa of the P. esculentus complex could be distinguished from each other with high confidence. Three more loci (Res3, Res5 and Res17) provided a powerful discrimination of the exotic species.

Evaluation of use of tiletamine/zolazepam for anesthesia of bullfrogs and leopard frogs.

PubMed

Letcher, J; Durante, R

1995-07-01

Use of tiletamine hydrochloride and zolazepam hydrochloride (1:1 fixed ratio combination) as an anesthetic agent in 2 anuran species was studied. A dosage of 5 mg/kg of body weight, administered IM, resulted in variable weak tranquilization. Intramuscular administration at dosages of 10 and 20 mg/kg induced variable states of tranquilization or anesthesia in leopard frogs (Rana pipiens) and bullfrogs (R catesbeiana). The dosages of 50 mg/kg induced anesthesia with greater consistency than lower dosages in bullfrogs, but resulted in mortalities. The same dosage was uniformly fatal in leopard frogs. Neither gross nor histologic lesions were identified in the frogs that died. Depth and duration of anesthesia was dosage related. At the 20 and 50 mg/kg dosages, leopard frogs attained a greater depth of anesthesia and remained anesthetized for a significantly greater duration than did bullfrogs; however, at the 5 and 10 mg/kg dosages, bullfrogs developed greater tranquilization for longer periods than did leopard frogs. Results of this study revealed profound intraspecies variation in depth and duration of effect of tiletamine/zolazepam; therefore, the drug does not appear to be a suitable injectable anesthetic in anurans.

Frog decline, frog malformations, and a comparison of frog and human health.

PubMed

Cohen, M M

2001-11-22

The decline in frog populations and the increase in the frequency of frog malformations are discussed. Topics considered for analysis include chytridiomycosis, retinoids, UV-B radiation, chemical contaminants, environmental threats, introduced invasive species and predation, unsustainable use, and enigmatic decline. Care must be taken to distinguish between hypotheses, laboratory experiments, and the findings in feral frog populations. Clearly, the causes of population decline and malformations are heterogeneous. The subject of frogs and humans is addressed under three subheadings: the importance of frogs to human societies, medical implications of frog studies, and a comparison of frog and human disease factors. Copyright 2001 Wiley-Liss, Inc.

Cystic urolithiasis in captive waxy monkey frogs (Phyllomedusa sauvagii).

PubMed

Archibald, Kate E; Minter, Larry J; Dombrowski, Daniel S; O'Brien, Jodi L; Lewbart, Gregory A

2015-03-01

The waxy monkey frog (Phyllomedusa sauvagii) is an arboreal amphibian native to arid regions of South America, and it has developed behavioral and physiologic adaptations to permit survival in dry environments. These adaptations include a uricotelic nitrogen metabolism and unique cutaneous lipid excretions to prevent evaporative water loss. Uroliths are a rare finding in amphibians. Six adult, presumed wild-caught waxy monkey frogs housed in a museum animal collection were diagnosed with cystic urolithiasis over a 7-yr period, and a single animal was diagnosed with four recurrent cases. Six cases were identified incidentally at routine physical or postmortem examination and four cases were identified during veterinary evaluation for coelomic distension, lethargy, anorexia, and increased soaking behavior. Calculi were surgically removed from three frogs via cystotomy, and a single frog underwent three cystotomies and two cloacotomies for recurrent urolithiasis. Two frogs died within the 24-hr postoperative period. Two representative calculi from a single frog were submitted for component analysis and found to consist of 100% ammonium urate. In the present report, cystic calculi are proposed to be the result of a high-protein diet based on a single invertebrate source, coupled with uricotelism, dehydration, increased cutaneous water loss, body temperature fluctuations facilitating supersaturation of urine, and subsequent accumulation and precipitation of urogenous wastes within the urinary bladder. Surgical cystotomy represents a short-term treatment strategy for this condition. Preventative measures, such as supplying a diversified and balanced diet in addition to environmental manipulation aimed at promoting adequate hydration, are anticipated to be more-rewarding management tools for cystic urolithiasis in the waxy monkey frog.

Leap Frog Digital Sensors and Definition, Integration & Testing FY 2003 Annual Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meitzler, Wayne D.; Ouderkirk, Steven J.; Shoemaker, Steven V.

2003-12-31

The objective of Leap Frog is to develop a comprehensive security tool that is transparent to the user community and more effective than current methods for preventing and detecting security compromises of critical physical and digital assets. Current security tools intrude on the people that interact with these critical assets by requiring them to perform additional functions or having additional visible sensors. Leap Frog takes security to the next level by being more effective and reducing the adverse impact on the people interacting with protected assets.

A Hopping Good Time: Wood Frogs in the Classroom.

ERIC Educational Resources Information Center

Shimkanin, John; Ulm, Glenn; King, Trina

1998-01-01

Presents a case for using wood frogs to study biology with students. Offers tips on where to find the eggs, how to care for them, what to expect as they hatch, and how to engage students in a study of their stages of development. (DDR)

Hybrid Surface Patterns Mimicking the Design of the Adhesive Toe Pad of Tree Frog.

PubMed

Xue, Longjian; Sanz, Belén; Luo, Aoyi; Turner, Kevin T; Wang, Xin; Tan, Di; Zhang, Rui; Du, Hang; Steinhart, Martin; Mijangos, Carmen; Guttmann, Markus; Kappl, Michael; Del Campo, Aránzazu

2017-10-24

Biological materials achieve directional reinforcement with oriented assemblies of anisotropic building blocks. One such example is the nanocomposite structure of keratinized epithelium on the toe pad of tree frogs, in which hexagonal arrays of (soft) epithelial cells are crossed by densely packed and oriented (hard) keratin nanofibrils. Here, a method is established to fabricate arrays of tree-frog-inspired composite micropatterns composed of polydimethylsiloxane (PDMS) micropillars embedded with polystyrene (PS) nanopillars. Adhesive and frictional studies of these synthetic materials reveal a benefit of the hierarchical and anisotropic design for both adhesion and friction, in particular, at high matrix-fiber interfacial strengths. The presence of PS nanopillars alters the stress distribution at the contact interface of micropillars and therefore enhances the adhesion and friction of the composite micropattern. The results suggest a design principle for bioinspired structural adhesives, especially for wet environments.

Hybrid Surface Patterns Mimicking the Design of the Adhesive Toe Pad of Tree Frog

PubMed Central

2017-01-01

Biological materials achieve directional reinforcement with oriented assemblies of anisotropic building blocks. One such example is the nanocomposite structure of keratinized epithelium on the toe pad of tree frogs, in which hexagonal arrays of (soft) epithelial cells are crossed by densely packed and oriented (hard) keratin nanofibrils. Here, a method is established to fabricate arrays of tree-frog-inspired composite micropatterns composed of polydimethylsiloxane (PDMS) micropillars embedded with polystyrene (PS) nanopillars. Adhesive and frictional studies of these synthetic materials reveal a benefit of the hierarchical and anisotropic design for both adhesion and friction, in particular, at high matrix–fiber interfacial strengths. The presence of PS nanopillars alters the stress distribution at the contact interface of micropillars and therefore enhances the adhesion and friction of the composite micropattern. The results suggest a design principle for bioinspired structural adhesives, especially for wet environments. PMID:28885831

When dinner is dangerous: toxic frogs elicit species-specific responses from a generalist snake predator.

PubMed

Phillips, Ben; Shine, Richard

2007-12-01

In arms races between predators and prey, some evolved tactics are unbeatable by the other player. For example, many types of prey are inedible because they have evolved chemical defenses. In this case, prey death removes any selective advantage of toxicity to the prey but not the selective advantage to a predator of being able to consume the prey. In the absence of effective selection for postmortem persistence of the toxicity then, some chemical defenses probably break down rapidly after prey death. If so, predators can overcome the toxic defense simply by waiting for that breakdown before consuming the prey. Floodplain death adders (Acanthophis praelongus) are highly venomous frog-eating elapid snakes native to northern Australia. Some of the frogs they eat are nontoxic (Litoria nasuta), others produce gluelike mucus when seized by a predator (Limnodynastes convexiusculus), and one species (Litoria dahlii) is dangerously toxic to snakes. Both the glue and the toxin degrade within about 20 min of prey death. Adders deal with these prey types in different and highly stereotyped ways: they consume nontoxic frogs directly but envenomate and release the other taxa, waiting until the chemical defense loses its potency before consuming the prey.

Correlated factors in amphibian decline: Exotic species and habitat change in western Washington

USGS Publications Warehouse

Adams, Michael J.

1999-01-01

Amphibian declines may frequently be associated with multiple, correlated factors. In western North America, exotic species and hydrological changes are often correlated and are considered 2 of the greatest threats to freshwater systems. Bullfrog (Rana catesbeiana) introductions are frequently cited as a threat to lentic-breeding anurans native to western North America and are a suspected factor in the decline of red-legged frogs (Rana aurora) in California. Introduced fish and habitat change are cited less frequently but are equally viable hypotheses. I examined the relation among introduced species, habitat, and the distribution and abundance of red-legged frogs in western Washington. Red-legged frog occurrence in the Puget Lowlands was more closely associated with habitat structure and the presence of exotic fish than with the presence of bull-frogs. The spread of exotics is correlated with a shift toward greater permanence in wetland habitats regionally. Conservation of more ephemeral wetland habitats may have direct benefits for some native amphibians and may also reduce the threat of exotic fish and bullfrogs, both of which were associated with permanent wetlands. Research and conservation efforts for lowland anurans in the West should emphasize the complexities of multiple contributing factors to amphibian losses.

Specific limb abnormalities induced by hydrogen peroxide in tadpoles of Indian jumping frog, Polypedates maculatus.

PubMed

Mahapatra, P K; Mohanty-Hejmadi, P; Chainy, G B

2001-11-01

Hydrogen peroxide (H2O2), one of the reactive oxygen intermediates (ROI) and a potential inducer of nuclear transcription factors induces consistent type of abnormal limb development (truncated with bent skeletal elements) in the tadpoles of Indian jumping frog, Polypedates maculatus.

The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Frogs and its Role in Frog Development and Reproduction

EPA Science Inventory

Metamorphosis of the amphibian tadpole is a thyroid hormone (TH)-dependent developmental process. For this reason, the tadpole is considered to be an ideal bioassay system to identify disruption of thyroid function by environmental contaminants. Here we provide an in-depth review...

The Developmental Effects Of A Municipal Wastewater Effluent On The Northern Leopard Frog, Rana pipiens

EPA Science Inventory

Wastewater effluents are complex mixtures containing a variety of anthropogenic compounds, many of which are known endocrine disruptors. In order to characterize the development and behavorial effects of such a complex mixture, northern leopard frogs, Rana pipiens, were e...

Investigating the distributional limits of the coastal tailed frog (Ascaphus truei) near its southern range terminus

Treesearch

Robert B. Douglas; David W. Ulrich; Christopher A. Morris; Matthew O. Goldsworthy

2017-01-01

Documenting species distribution patterns and habitat associations is a necessary prerequisite for developing conservation measures, prioritizing areas for habitat restoration, and establishing baseline conditions for long-term monitoring programs. The coastal tailed frog (Ascaphus truei) ranges from coastal British Columbia to...

Effects of Environmental Contamination and Acute Toxicity of N-Nitrate on Early Life Stages of Endemic Arboreal Frog, Polypedates cruciger (Blyth, 1852).

PubMed

Balangoda, Anusha; Deepananda, K H M Ashoka; Wegiriya, H C E

2018-02-01

This study investigated the potential toxic effects of environmentally relevant nitrate concentrations on development, growth, and mortality of early life stages of common hour-glass tree frog, Polypedates cruciger. Tadpoles from hatchlings through pre-adult were exposed to environmentally relevant nitrate concentrations detected in Mirissa, Sri Lanka. Newly hatched, external gill stage, and internal gill stage tadpoles were exposed to potassium nitrate for bioassay tests. No behavioral changes or abnormalities were observed in control and nitrate-induced group. However, detected environmental nitrate concentration significantly increased (p < 0.05) the growth of the tadpoles up to 25 days old. Results revealed that newly hatched and external gill stage was more susceptible to the nitrate pollution than internal gill stage. The results suggest that environmentally relevant nitrate can cause mortality on the amphibian population in ecosystems associated with agro-pastoral activities through altering the growth and direct toxicological effects on the survivorship.

From The Cover: Microtransplantation of functional receptors and channels from the Alzheimer's brain to frog oocytes

NASA Astrophysics Data System (ADS)

Miledi, R.; Dueñas, Z.; Martinez-Torres, A.; Kawas, C. H.; Eusebi, F.

2004-02-01

About a decade ago, cell membranes from the electric organ of Torpedo and from the rat brain were transplanted to frog oocytes, which thus acquired functional Torpedo and rat neurotransmitter receptors. Nevertheless, the great potential that this method has for studying human diseases has remained virtually untapped. Here, we show that cell membranes from the postmortem brains of humans that suffered Alzheimer's disease can be microtransplanted to the plasma membrane of Xenopus oocytes. We show also that these postmortem membranes carry neurotransmitter receptors and voltage-operated channels that are still functional, even after they have been kept frozen for many years. This method provides a new and powerful approach to study directly the functional characteristics and structure of receptors, channels, and other membrane proteins of the Alzheimer's brain. This knowledge may help in understanding the basis of Alzheimer's disease and also help in developing new treatments. -aminobutyric acid receptors | sodium channels | calcium channels | postmortem brain

Behavioural, ecological, and evolutionary aspects of diversity in frog colour patterns.

PubMed

Rojas, Bibiana

2017-05-01

The role of colours and colour patterns in behavioural ecology has been extensively studied in a variety of contexts and taxa, while almost overlooked in many others. For decades anurans have been the focus of research on acoustic signalling due to the prominence of vocalisations in their communication. Much less attention has been paid to the enormous diversity of colours, colour patterns, and other types of putative visual signals exhibited by frogs. With the exception of some anecdotal observations and studies, the link between colour patterns and the behavioural and evolutionary ecology of anurans had not been addressed until approximately two decades ago. Since then, there has been ever-increasing interest in studying how colouration is tied to different aspects of frog behaviour, ecology and evolution. Here I review the literature on three different contexts in which frog colouration has been recently studied: predator-prey interactions, intraspecific communication, and habitat use; and I highlight those aspects that make frogs an excellent, yet understudied, group to examine the role of colour in the evolution of anti-predation strategies and animal communication systems. Further, I argue that in addition to natural-history observations, more experiments are needed in order to elucidate the functions of anuran colouration and the selective pressures involved in its diversity. To conclude, I encourage researchers to strengthen current experimental approaches, and suggest future directions that may broaden our current understanding of the adaptive value of anuran colour pattern diversity. © 2016 Cambridge Philosophical Society.

Budgett's frog (Lepidobatrachus laevis): A new amphibian embryo for developmental biology.

PubMed

Amin, Nirav M; Womble, Mandy; Ledon-Rettig, Cristina; Hull, Margaret; Dickinson, Amanda; Nascone-Yoder, Nanette

2015-09-15

The large size and rapid development of amphibian embryos has facilitated ground-breaking discoveries in developmental biology. Here, we describe the embryogenesis of the Budgett's frog (Lepidobatrachus laevis), an unusual species with eggs that are over twice the diameter of laboratory Xenopus, and embryos that can tolerate higher temperatures to develop into a tadpole four times more rapidly. In addition to detailing their early development, we demonstrate that, like Xenopus, these embryos are amenable to explant culture assays and can express exogenous transcripts in a tissue-specific manner. Moreover, the steep developmental trajectory and large scale of Lepidobatrachus make it exceptionally well-suited for morphogenesis research. For example, the developing organs of the Budgett's frog are massive compared to those of most model species, and are composed of larger individual cells, thereby affording increased subcellular resolution of early vertebrate organogenesis. Furthermore, we found that complete limb regeneration, which typically requires months to achieve in most vertebrate models, occurs in a matter of days in the Budgett's tadpole, which substantially accelerates the pace of experimentation. Thus, the unusual combination of the greater size and speed of the Budgett's frog model provides inimitable advantages for developmental studies-and a novel inroad to address the mechanisms of spatiotemporal scaling during evolution. Copyright © 2015 Elsevier Inc. All rights reserved.

Budgett’s frog (Lepidobatrachus laevis): a new amphibian embryo for developmental biology

PubMed Central

Amin, Nirav M.; Womble, Mandy; Ledon-Rettig, Cris; Hull, Margaret; Dickinson, Amanda; Nascone-Yoder, Nanette

2015-01-01

The large size and rapid development of amphibian embryos has facilitated ground-breaking discoveries in developmental biology. Here, we describe the embryogenesis of the Budgett’s frog (Lepidobatrachus laevis), an unusual species with eggs that are over twice the diameter of laboratory Xenopus, and embryos that can tolerate higher temperatures to develop into a tadpole four times more rapidly. In addition to detailing their early development, we demonstrate that, like Xenopus, these embryos are amenable to explant culture assays and can express exogenous transcripts in a tissue-specific manner. Moreover, the steep developmental trajectory and large scale of Lepidobatrachus make it exceptionally well-suited for morphogenesis research. For example, the developing organs of the Budgett’s frog are massive compared to those of most model species, and are composed of larger individual cells, thereby affording increased subcellular resolution of early vertebrate organogenesis. Furthermore, we found that complete limb regeneration, which typically requires months to achieve in most vertebrate models, occurs in a matter of days in the Budgett’s tadpole, which substantially accelerates the pace of experimentation. Thus, the unusual combination of the greater size and speed of the Budgett’s frog model provides inimitable advantages for developmental studies—and a novel inroad to address the mechanisms of spatiotemporal scaling during evolution. PMID:26169245

Frogs as integrative models for understanding digestive organ development and evolution.

PubMed

Womble, Mandy; Pickett, Melissa; Nascone-Yoder, Nanette

2016-03-01

The digestive system comprises numerous cells, tissues and organs that are essential for the proper assimilation of nutrients and energy. Many aspects of digestive organ function are highly conserved among vertebrates, yet the final anatomical configuration of the gut varies widely between species, especially those with different diets. Improved understanding of the complex molecular and cellular events that orchestrate digestive organ development is pertinent to many areas of biology and medicine, including the regeneration or replacement of diseased organs, the etiology of digestive organ birth defects, and the evolution of specialized features of digestive anatomy. In this review, we highlight specific examples of how investigations using Xenopus laevis frog embryos have revealed insight into the molecular and cellular dynamics of digestive organ patterning and morphogenesis that would have been difficult to obtain in other animal models. Additionally, we discuss recent studies of gut development in non-model frog species with unique feeding strategies, such as Lepidobatrachus laevis and Eleutherodactylous coqui, which are beginning to provide glimpses of the evolutionary mechanisms that may generate morphological variation in the digestive tract. The unparalleled experimental versatility of frog embryos make them excellent, integrative models for studying digestive organ development across multiple disciplines. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bioaccumulation of polychlorinated biphenyls in ranid frogs and northern water snakes from a hazardous waste site and a contaminated watershed.

PubMed

Fontenot, L W; Noble, G P; Akins, J M; Stephens, M D; Cobb, G P

2000-04-01

Livers of bullfrogs (Rana catesbeiana) from a polychlorinated biphenyl (PCB) contaminated watershed and hazardous waste site located in Pickens County, South Carolina, contained significantly higher concentrations of PCBs (2.33 and 2.26 ppm, respectively) than those from a reference site (0.05 ppm). Green frogs (R. clamitans) from the two contaminated sites also accumulated higher levels of PCBs (2.37 and 3.88 ppm, respectively) than those from the reference site (0.02 ppm). No temporal variation was observed in PCB concentrations of bullfrogs or green frogs from the contaminated sites between 1992 and 1993. Levels of PCBs in the livers of northern water snakes (Nerodia sipedon) were significantly higher in snakes from the contaminated watershed (13.70 ppm) than in those from the waste site (2.29 ppm) and two reference sites (2.50 and 1.23 ppm). When compared to frogs, significantly higher bioaccumulation occurred in water snakes from the contaminated watershed. No significant differences in PCB levels were found with respect to sex or body size (snout-vent length (SVL) or body mass) for frogs or snakes. PCBs were detected also in eggs of both frogs and snakes. Results of this study provide baseline data and document the bioaccumulation of PCB residues in frog and snake tissues; however, the significance of these tissue residues to reproduction, survival, growth/development, and population dynamics in contaminated habitats is unknown.

Seasonal Pattern of Batrachochytrium dendrobatidis Infection and Mortality in Lithobates areolatus: Affirmation of Vredenburg's “10,000 Zoospore Rule”

PubMed Central

Kinney, Vanessa C.; Heemeyer, Jennifer L.; Pessier, Allan P.; Lannoo, Michael J.

2011-01-01

To fully comprehend chytridiomycosis, the amphibian disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), it is essential to understand how Bd affects amphibians throughout their remarkable range of life histories. Crawfish Frogs (Lithobates areolatus) are a typical North American pond-breeding species that forms explosive spring breeding aggregations in seasonal and semipermanent wetlands. But unlike most species, when not breeding Crawfish Frogs usually live singly—in nearly total isolation from conspecifics—and obligately in burrows dug by crayfish. Crayfish burrows penetrate the water table, and therefore offer Crawfish Frogs a second, permanent aquatic habitat when not breeding. Over the course of two years we sampled for the presence of Bd in Crawfish Frog adults. Sampling was conducted seasonally, as animals moved from post-winter emergence through breeding migrations, then back into upland burrow habitats. During our study, 53% of Crawfish Frog breeding adults tested positive for Bd in at least one sample; 27% entered breeding wetlands Bd positive; 46% exited wetlands Bd positive. Five emigrating Crawfish Frogs (12%) developed chytridiomycosis and died. In contrast, all 25 adult frogs sampled while occupying upland crayfish burrows during the summer tested Bd negative. One percent of postmetamorphic juveniles sampled were Bd positive. Zoospore equivalents/swab ranged from 0.8 to 24,436; five out of eight frogs with zoospore equivalents near or >10,000 are known to have died. In summary, Bd infection rates in Crawfish Frog populations ratchet up from near zero during the summer to over 25% following overwintering; rates then nearly double again during and just after breeding—when mortality occurs—before the infection wanes during the summer. Bd-negative postmetamorphic juveniles may not be exposed again to this pathogen until they take up residence in crayfish burrows, or until their first breeding, some years later. PMID:21423745

Minimal Model of Prey Localization through the Lateral-Line System

NASA Astrophysics Data System (ADS)

Franosch, Jan-Moritz P.; Sobotka, Marion C.; Elepfandt, Andreas; van Hemmen, J. Leo

2003-10-01

The clawed frog Xenopus is an aquatic predator catching prey at night by detecting water movements caused by its prey. We present a general method, a “minimal model” based on a minimum-variance estimator, to explain prey detection through the frog's many lateral-line organs, even in case several of them are defunct. We show how waveform reconstruction allows Xenopus' neuronal system to determine both the direction and the character of the prey and even to distinguish two simultaneous wave sources. The results can be applied to many aquatic amphibians, fish, or reptiles such as crocodilians.

Frequency-resolved optical gating system with a tellurium crystal for characterizing free-electron lasers in the wavelength range of 10-30 {mu}m

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iijima, Hokuto; Nagai, Ryoji; Nishimori, Nobuyuki

2009-12-15

A second-harmonic generation frequency-resolved optical gating (SHG-FROG) system has been developed for the complete characterization of laser pulses in the wavelength range of 10-30 {mu}m. A tellurium crystal is used so that spectrally resolved autocorrelation signals with a good signal-to-noise ratio are obtained. Pulses (wavelength {approx}22 {mu}m) generated from a free-electron laser are measured by the SHG-FROG system. The SHG intensity profile and the spectrum obtained by FROG measurements are well consistent with those of independent measurements of the pulse length and spectrum. The pulse duration and spectral width determined from the FROG trace are 0.6 ps and 5.2 THzmore » at full width half maximum, respectively.« less

Differential sensitivity to the antifouling chemical medetomidine between wood frog and American toad tadpoles with evidence for low-dose stimulation and high-dose inhibition of metamorphosis.

PubMed

Fong, Peter P; Lambert, Olivia J; Hoagland, Margot L; Kurtz, Emily R

2018-05-05

Antifouling chemicals are legacy contaminants in aquatic ecosystems. Previous experiments have shown that a 14-day exposure to the antifouling chemical medetomidine delays metamorphosis and reduces body mass in wood frog tadpoles. In the present study, we exposed wood frog tadpoles to medetomidine for 3, 7, and 10 days at 100 nM, 1 μM, and 10 μM. We also exposed American toad tadpoles to medetomidine for 3 days at four concentrations (10 nM, 100 nM, 1 μM, and 10 μM) in static renewal experiments. In each experiment, we measured growth, frequency and time to metamorphosis, and mass at metamorphosis. In both species, medetomidine significantly slowed development as measured by the Gosner stage. After 34 days in culture, wood frog tadpoles exposed to 1 and 10 μM medetomidine for as few as 3 days were significantly less developed compared to controls. Toads exposed to 1 μM medetomidine for 3 days were also significantly less developed on day 27, but by day 34, there was no difference from controls. For wood frogs, medetomidine significantly affected time to metamorphosis with a trend for tadpoles at lower concentrations metamorphosing sooner than those at higher concentrations. While medetomidine affected time to metamorphosis in wood frogs, it did not affect fresh mass, dry mass, or mortality compared to controls. Wood frog tadpoles that did not metamorphose after over 90 days in culture were more frequent in high-concentration groups than in the control. In toads, 10 μM medetomidine was 100% lethal within 23 days, but at the same concentration and duration, no wood frog tadpoles died. Lower concentrations were also significantly lethal to toads compared to controls, but tadpoles that survived in 10 and 100 nM metamorphosed sooner than those in 1 μM. Fresh mass of toad tadpoles exposed to 1 μm was significantly smaller at metamorphosis compared to that of controls. Medetomidine also affected the behavior of tadpoles. In toads, medetomidine significantly reduced both percent activity and startle response. In wood frogs, medetomidine significantly reduced percent activity, but increased startle response. We discuss our finding of low-dose stimulation and high-dose inhibition of different life history endpoints in terms of hormetic mechanisms. The differential sensitivity between species in terms of mortality, frequency of metamorphosis, and behavior highlights the potential negative environmental effects of medetomidine to amphibians.

Virtual Frog Dissection Kit Version 2.2

Science.gov Websites

Virtual Frog Dissection Kit This award-winning interactive program is part of the "Whole Frog " project. You can interactively dissect a (digitized) frog named Fluffy, and play the Virtual Frog animals other than the frog that have a computer-graphics based virtual dissection page. We get frequent

Behavioral Repertoire of Xenopus tropicalis: Baseline Female-male Interactions during Spawning Events and Male Vocal Communication

EPA Science Inventory

The aquatic frog, Xenopus tropicalis, is being developed for use as a model amphibian species for inclusion in the EPA’s Endocrine Disruptor Screening Program. Current toxicity test designs do not incorporate measures of fecundity due to high variability in the responses of frog...

A Comparison of V-Frog[C] to Physical Frog Dissection

ERIC Educational Resources Information Center

Lalley, James P.; Piotrowski, Phillip S.; Battaglia, Barbara; Brophy, Keith; Chugh, Kevin

2010-01-01

The purpose of the present study was to examine and compare the effectiveness of virtual frog dissection using V-Frog[C] and physical frog dissection on learning, retention, and affect. Subjects were secondary students enrolled in year-long life science classes in a suburban high school (N=102). Virtual dissections were done with V-Frog[C], a…

To Be or Not to Be...a Frog: The Frog Prince and Shifting Paradigms.

ERIC Educational Resources Information Center

Crane, Lisa Marie

1997-01-01

Discusses three modern variations of the classic "Frog Prince" folk tale: "Pondlarker" (Fred Gwynne); "The Frog Prince Continued" (Jon Scieszka); and "The Prince of the Pond" (Donna Jo Napoli). Notes that these variants create a world in which frogs can have values, wisdom, and emotion, and in which frogs can influence the ways of humanity. (RS)

Effects of water vapor density on cutaneous resistance to evaporative water loss and body temperature in green tree frogs (Hyla cinerea).

PubMed

Wygoda, Mark L; Kersten, Constance A

2013-01-01

Increased cutaneous resistance to evaporative water loss (Rc) in tree frogs results in decreased water loss rate and increased body temperature. We examined sensitivity of Rc to water vapor density (WVD) in Hyla cinerea by exposing individual frogs and agar models to four different WVD environments and measuring cutaneous evaporative water loss rate and body temperature simultaneously using a gravimetric wind tunnel measuring system. We found that water loss rate varied inversely and body temperature directly with WVD but that models were affected to a greater extent than were animals. Mean Rc was significantly different between the highest WVD environment and each of the three drier environments but did not differ among the drier environments, indicating that Rc initially increases and then reaches a plateau in response to decreasing WVD. Rc was equivalent when calculated using either WVD difference or WVD deficit as the driving force for evaporation. We also directly observed secretions from cutaneous glands while measuring body temperature and tested secretions and skin samples for the presence of lipids. We found that irregular transient body temperature depressions observed during wind tunnel trials occur due to evaporative cooling from intermittent skin secretions containing lipids, although we were unable to identify lipid-secreting glands.

Pulse retrieval algorithm for interferometric frequency-resolved optical gating based on differential evolution.

PubMed

Hyyti, Janne; Escoto, Esmerando; Steinmeyer, Günter

2017-10-01

A novel algorithm for the ultrashort laser pulse characterization method of interferometric frequency-resolved optical gating (iFROG) is presented. Based on a genetic method, namely, differential evolution, the algorithm can exploit all available information of an iFROG measurement to retrieve the complex electric field of a pulse. The retrieval is subjected to a series of numerical tests to prove the robustness of the algorithm against experimental artifacts and noise. These tests show that the integrated error-correction mechanisms of the iFROG method can be successfully used to remove the effect from timing errors and spectrally varying efficiency in the detection. Moreover, the accuracy and noise resilience of the new algorithm are shown to outperform retrieval based on the generalized projections algorithm, which is widely used as the standard method in FROG retrieval. The differential evolution algorithm is further validated with experimental data, measured with unamplified three-cycle pulses from a mode-locked Ti:sapphire laser. Additionally introducing group delay dispersion in the beam path, the retrieval results show excellent agreement with independent measurements with a commercial pulse measurement device based on spectral phase interferometry for direct electric-field retrieval. Further experimental tests with strongly attenuated pulses indicate resilience of differential-evolution-based retrieval against massive measurement noise.

Accelerated hatching of southern leopard frog (Rana sphenocephala) eggs in response to the presence of a crayfish Procambarus nigrocinctus predator

Treesearch

Daniel Saenz; James B. Johnson; Cory K. Adams; Gage H. Dayton

2003-01-01

Phenotypic plasticity, such as morphological and behavioral changes in response to predators, is common in larval anurans. Less is known about inducible defenses in the embryonic stages of development. We investigated the predation risk imposed by crayfish (Procambarus nigrocinctus) on southern leopard frog (Rana sphenocephala)...

Discovery of Phylloseptins that Defense against Gram-Positive Bacteria and Inhibit the Proliferation of the Non-Small Cell Lung Cancer Cell Line, from the Skin Secretions of Phyllomedusa Frogs.

PubMed

Liu, Jia; Wu, Qing; Li, Lei; Xi, Xinping; Wu, Di; Zhou, Mei; Chen, Tianbao; Shaw, Chris; Wang, Lei

2017-08-29

The growing occurrence of bacterial resistance to conventional antibiotics has called for the development of new classes of antimicrobial agents. Antimicrobial peptides (AMPs) with broad antimicrobial spectrum derived from frog skin secretions have been demonstrated to be promising candidates for new antibiotic development. A proven rich source of these compounds are the skin secretions of the frogs in the Phyllomedusa genus. In this study, two novel phylloseptin peptides-phylloseptin-PTa and phylloseptin-PHa-were isolated from the skin secretions of the South American frogs, Phyllomedusa tarsius ( P. tarsius ) and Phyllomedusa hypochondrialis ( P. hypochondrialis ) through parallel transcriptomic and peptidomic studies. Replicates obtained by chemical synthesis were structurally analysed and shown to adopt an α-helix configuration in an amphiphilic environment. Both peptides demonstrated antimicrobial activities against planktonic Gram-positive bacteria strains, including Staphylococcus aureus , Enterococcus faecalis and methicillin-resistant Staphylococcus aureus , biofilms, as well as cytostatic effects on the non-small cell lung cancer cell line, NCI-H157, with relatively low haemolysis on horse erythrocytes and low cytotoxicity on the human microvascular endothelial cell line, HMEC-1. The discovery of phylloseptin peptides may further inspire the development of new types of antibiotics.

Tourism and the conservation of critically endangered frogs.

PubMed

Morrison, Clare; Simpkins, Clay; Castley, J Guy; Buckley, Ralf C

2012-01-01

Protected areas are critical for the conservation of many threatened species. Despite this, many protected areas are acutely underfunded, which reduces their effectiveness significantly. Tourism is one mechanism to promote and fund conservation in protected areas, but there are few studies analyzing its tangible conservation outcomes for threatened species. This study uses the 415 IUCN critically endangered frog species to evaluate the contribution of protected area tourism revenue to conservation. Contributions were calculated for each species as the proportion of geographic range inside protected areas multiplied by the proportion of protected area revenues derived from tourism. Geographic ranges were determined from IUCN Extent of Occurrence maps. Almost 60% (239) of critically endangered frog species occur in protected areas. Higher proportions of total range are protected in Nearctic, Australasian and Afrotopical regions. Tourism contributions to protected area budgets ranged from 5-100%. These financial contributions are highest for developing countries in the Afrotropical, Indomalayan and Neotropical regions. Data for both geographic range and budget are available for 201 critically endangered frog species with proportional contributions from tourism to species protection ranging from 0.8-99%. Tourism's financial contributions to critically endangered frog species protection are highest in the Afrotropical region. This study uses a coarse measure but at the global scale it demonstrates that tourism has significant potential to contribute to global frog conservation efforts.

Tourism and the Conservation of Critically Endangered Frogs

PubMed Central

Morrison, Clare; Simpkins, Clay; Castley, J. Guy; Buckley, Ralf C.

2012-01-01

Protected areas are critical for the conservation of many threatened species. Despite this, many protected areas are acutely underfunded, which reduces their effectiveness significantly. Tourism is one mechanism to promote and fund conservation in protected areas, but there are few studies analyzing its tangible conservation outcomes for threatened species. This study uses the 415 IUCN critically endangered frog species to evaluate the contribution of protected area tourism revenue to conservation. Contributions were calculated for each species as the proportion of geographic range inside protected areas multiplied by the proportion of protected area revenues derived from tourism. Geographic ranges were determined from IUCN Extent of Occurrence maps. Almost 60% (239) of critically endangered frog species occur in protected areas. Higher proportions of total range are protected in Nearctic, Australasian and Afrotopical regions. Tourism contributions to protected area budgets ranged from 5–100%. These financial contributions are highest for developing countries in the Afrotropical, Indomalayan and Neotropical regions. Data for both geographic range and budget are available for 201 critically endangered frog species with proportional contributions from tourism to species protection ranging from 0.8–99%. Tourism's financial contributions to critically endangered frog species protection are highest in the Afrotropical region. This study uses a coarse measure but at the global scale it demonstrates that tourism has significant potential to contribute to global frog conservation efforts. PMID:22984440

Verbal Semantics Drives Early Anticipatory Eye Movements during the Comprehension of Verb-Initial Sentences.

PubMed

Sauppe, Sebastian

2016-01-01

Studies on anticipatory processes during sentence comprehension often focus on the prediction of postverbal direct objects. In subject-initial languages (the target of most studies so far), however, the position in the sentence, the syntactic function, and the semantic role of arguments are often conflated. For example, in the sentence "The frog will eat the fly" the syntactic object ("fly") is at the same time also the last word and the patient argument of the verb. It is therefore not apparent which kind of information listeners orient to for predictive processing during sentence comprehension. A visual world eye tracking study on the verb-initial language Tagalog (Austronesian) tested what kind of information listeners use to anticipate upcoming postverbal linguistic input. The grammatical structure of Tagalog allows to test whether listeners' anticipatory gaze behavior is guided by predictions of the linear order of words, by syntactic functions (e.g., subject/object), or by semantic roles (agent/patient). Participants heard sentences of the type "Eat frog fly" or "Eat fly frog" (both meaning "The frog will eat the fly") while looking at displays containing an agent referent ("frog"), a patient referent ("fly") and a distractor. The verb carried morphological marking that allowed the order and syntactic function of agent and patient to be inferred. After having heard the verb, listeners fixated on the agent irrespective of its syntactic function or position in the sentence. While hearing the first-mentioned argument, listeners fixated on the corresponding referent in the display accordingly and then initiated saccades to the last-mentioned referent before it was encountered. The results indicate that listeners used verbal semantics to identify referents and their semantic roles early; information about word order or syntactic functions did not influence anticipatory gaze behavior directly after the verb was heard. In this verb-initial language, event semantics takes early precedence during the comprehension of sentences, while arguments are anticipated temporally more local to when they are encountered. The current experiment thus helps to better understand anticipation during language processing by employing linguistic structures not available in previously studied subject-initial languages.

The role of predators in maintaining the geographic organization of aposematic signals.

PubMed

Chouteau, Mathieu; Angers, Bernard

2011-12-01

Selective predation of aposematic signals is expected to promote phenotypic uniformity. But while these signals may be uniform within a population, numerous species display impressive variations in warning signals among adjacent populations. Predators from different localities who learn to avoid distinct signals while performing intense selection on others are thus expected to maintain such a geographic organization. We tested this assumption by placing clay frog models, representing distinct color morphs of the Peruvian poison dart frog Ranitomeya imitator and a nonconspicuous frog, reciprocally between adjacent localities. In each locality, avian predators were able to discriminate between warning signals; the adjacent exotic morph experienced up to four times more attacks than the local one and two times more than the nonconspicuous phenotype. Moreover, predation attempts on the exotic morph quickly decreased to almost nil, suggesting rapid learning. This experiment offers direct evidence for the existence of different predator communities performing localized homogenizing selection on distinct aposematic signals.

Inbreeding and road effect zone in a Ranidae: the case of Agile frog, Rana dalmatina Bonaparte, 1840.

PubMed

Lesbarrères, David; Pagano, Alain; Lodé, Thierry

2003-08-01

Inbreeding has often been invoked in the extinction of local populations. In eleven western France populations of Agile frog studied, observed heterozygosity was significantly lower than expected in all cases, giving new evidence of such a depression in small populations. It especially occurred in ponds located near an highway rather than in undisturbed populations (FIS = 0.544 and 0.315, respectively). Thus, our results argue for a "road effect zone". Discussing about road distance and conservation policies, we propose that roads are directly involved in inbreeding and in local extinction. Thus, road construction ought to consider conservation management.

Complete Genome Sequence of Frog virus 3, Isolated from a Strawberry Poison Frog (Oophaga pumilio) Imported from Nicaragua into the Netherlands

PubMed Central

Hughes, Joseph; van Beurden, Steven J.; Suárez, Nicolás M.; Haenen, Olga L. M.; Voorbergen-Laarman, Michal; Gröne, Andrea; Kik, Marja J. L.

2017-01-01

ABSTRACT Frog virus 3 was isolated from a strawberry poison frog (Oophaga pumilio) imported from Nicaragua via Germany to the Netherlands, and its complete genome sequence was determined. Frog virus 3 isolate Op/2015/Netherlands/UU3150324001 is 107,183 bp long and has a nucleotide similarity of 98.26% to the reference Frog virus 3 isolate. PMID:28860243

Predation by Oregon spotted frogs (Rana pretiosa) on Western toads (Bufo boreas) in Oregon, USA

USGS Publications Warehouse

Pearl, Christopher A.; Hayes, M.P.

2002-01-01

Toads of the genus Bufo co-occur with true frogs (family Ranidae) throughout their North American ranges. Yet, Bufo are rarely reported as prey for ranid frogs, perhaps due to dermal toxins that afford them protection from some predators. We report field observations from four different localities demonstrating that Oregon spotted frogs (Rana pretiosa) readily consume juvenile western toads (Bufo boreas) at breeding sites in Oregon. Unpalatability thought to deter predators of selected taxa and feeding mode may not protect juvenile stages of western toads from adult Oregon spotted frogs. Activity of juvenile western toads can elicit ambush behavior by Oregon spotted frog adults. Our review of published literature suggests that regular consumption of toadlets sets Oregon spotted frogs apart from most North American ranid frogs. Importance of the trophic context of juvenile western toads as a seasonally important resource to Oregon spotted frogs needs critical investigation.

Body wiping behaviors associated with cutaneous lipids in hylid tree frogs of Florida.

PubMed

Barbeau, Tamatha R; Lillywhite, Harvey B

2005-06-01

Body wiping behavior, integumentary secretions and rates of evaporative water loss (EWL) were examined in six species of Florida tree frogs (Anura: Hylidae). Additionally, morphology of the integument and dermal glands were compared among these and one other Florida tree frog (Hyla andersonii), an arid-adapted tree frog (Phyllomedusa hypochondrialis), and a highly aquatic frog (Rana utricularia). An extra-epidermal layer of lipid and mucus, presumably secreted from dermal granular glands, was detected on the skin of all Florida hylid frogs examined. Distinct body wiping behaviors were observed in the hylid frogs, but these were less complex than those described previously in phyllomedusine frogs, which occupy arid habitats, secrete lipids onto their skin, and are regarded as relatively 'waterproof'. Florida hylids occupy seasonally arid habitats and appear to have reduced rates of EWL. The suite of traits we observed in these frogs have been previously documented in a rhacophorid tree frog from seasonally arid regions of India and likely represent an evolutionary convergent response to periodic dehydration stress. The presence of lipids that are spread by simple wiping behaviors to form an extra-epidermal water barrier may represent an early stage of the more advanced adaptations described in more waterproof arboreal frogs.

Early-Life Diet Affects Host Microbiota and Later-Life Defenses Against Parasites in Frogs.

PubMed

Knutie, Sarah A; Shea, Lauren A; Kupselaitis, Marinna; Wilkinson, Christina L; Kohl, Kevin D; Rohr, Jason R

2017-10-01

Food resources can affect the health of organisms by altering their symbiotic microbiota and affecting energy reserves for host defenses against parasites. Different diets can vary in their macronutrient content and therefore they might favor certain bacterial communities of the host and affect the development and maintenance of the immune system, such as the inflammatory or antibody responses. Thus, testing the effect of diet, especially for animals with wide diet breadths, on host-associated microbiota and defenses against parasites might be important in determining infection and disease risk. Here, we test whether the early-life diet of Cuban tree frogs (Osteopilus septentrionalis) affects early- and later-life microbiota as well as later-life defenses against skin-penetrating, gut worms (Aplectana hamatospicula). We fed tadpoles two ecologically common diets: a diet of conspecifics or a diet of algae (Arthrospira sp.). We then: (1) characterized the gut microbiota of tadpoles and adults; and (2) challenged adult frogs with parasitic worms and measured host resistance (including the antibody-mediated immune response) and tolerance of infections. Tadpole diet affected bacterial communities in the guts of tadpoles but did not have enduring effects on the bacterial communities of adults. In contrast, tadpole diet had enduring effects on host resistance and tolerance of infections in adult frogs. Frogs that were fed a conspecific-based diet as tadpoles were more resistant to worm penetration compared with frogs that were fed an alga-based diet as tadpoles, but less resistant to worm establishment, which may be related to their suppressed antibody response during worm establishment. Furthermore, frogs that were fed a conspecific-based diet as tadpoles were more tolerant to the effect of parasite abundance on host mass during worm establishment. Overall, our study demonstrates that the diet of Cuban tree frog tadpoles affects the gut microbiota and defenses against parasitic gut worms of frogs, but these effects depend on the stage of the host and infection, respectively. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Antimicrobial peptides from the skins of North American frogs.

PubMed

Conlon, J Michael; Kolodziejek, Jolanta; Nowotny, Norbert

2009-08-01

North America is home to anuran species belonging to the families Bufonidae, Eleutherodactylidae, Hylidae, Leiopelmatidae, Ranidae, and Scaphiopodidae but antimicrobial peptides have been identified only in skin secretions and/or skin extracts of frogs belonging to the Leiopelmatidae ("tailed frogs") and Ranidae ("true frogs"). Eight structurally-related cationic alpha-helical peptides with broad-spectrum antibacterial activity, termed ascaphins, have been isolated from specimens of Ascaphus truei (Leiopelmatidae) occupying a coastal range. Characterization of orthologous antimicrobial peptides from Ascaphus specimens occupying an inland range supports the proposal that this population should be regarded as a separate species A. montanus. Ascaphin-8 shows potential for development into a therapeutically valuable anti-infective agent. Peptides belonging to the brevinin-1, esculentin-1, esculentin-2, palustrin-1, palustrin-2, ranacyclin, ranatuerin-1, ranatuerin-2, and temporin families have been isolated from North American ranids. It is proposed that "ranalexins" represent brevinin-1 peptides that have undergone a four amino acid residue internal deletion. Current taxonomic recommendations divide North American frogs from the family Ranidae into two genera: Lithobates and Rana. Cladistic analysis based upon the amino acid sequences of the brevinin-1 peptides provides strong support for this assignment.

Comparative Pathology and Ecological Implications of Two Myxosporean Parasites in Native Australian Frogs and the Invasive Cane Toad

PubMed Central

Hartigan, Ashlie; Dhand, Navneet K.; Rose, Karrie; Šlapeta, Jan; Phalen, David N.

2012-01-01

Myxosporean parasites Cystodiscus axonis and C. australis are pathogens of native and exotic Australian frog species. The pathology and ecological outcomes of infection with these parasites were investigated in this study. Gliosis was correlated to Cystodiscus axonis plasmodia in the brains of (9/60) tadpoles and (3/9) adult endangered Green and golden bell frogs using ordinal regression. Severe host reactions to C. axonis (haemorrhage, necrosis, and vasulitis) were observed in the brains of threatened Southern bell frogs (8/8), critically endangered Booroolong frogs (15/44) and Yellow spotted bell frogs (3/3). Severe brain lesions were associated with behavioural changes, neurological dysfunction, and spontaneous death. Both C. axonis and C. australis develop in the bile ducts of tadpoles, the plasmodia were significantly associated with biliary hyperplasia, inflammation and the loss of hepatocytes in (34/72) Green and golden bell frog tadpoles using ordinal regression. These lesions were so severe that in some cases 70% of the total liver was diseased. Normal liver function in tadpoles is necessary for metamorphosis, metabolism, and immune function. We postulate that this extensive liver damage would have significant host health impacts. Severe hepatic myxosporidiosis was more prevalent in tadpoles examined in autumn and winter (overwintered), suggestive of delayed metamorphosis in infected tadpoles, which would have serious flow-on effects in small populations. We compared the sensitivity of histopathology and species-specific PCR in the detection of C. australis and C. axonis. PCR was determined to be the most sensitive method (detection limit 1 myxospore equivalent of ribosomal DNA). Histology, however, had the advantage of assessing the impact of the parasite on the host. It was concluded that these parasites have the potential for significant ecological impacts, because of their high prevalence of infection and their ability to cause disease in some frogs. PMID:23056175

Complete Genome Sequence of Frog virus 3, Isolated from a Strawberry Poison Frog (Oophaga pumilio) Imported from Nicaragua into the Netherlands.

PubMed

Saucedo, Bernardo; Hughes, Joseph; van Beurden, Steven J; Suárez, Nicolás M; Haenen, Olga L M; Voorbergen-Laarman, Michal; Gröne, Andrea; Kik, Marja J L

2017-08-31

Frog virus 3 was isolated from a strawberry poison frog ( Oophaga pumilio ) imported from Nicaragua via Germany to the Netherlands, and its complete genome sequence was determined. Frog virus 3 isolate Op /2015/Netherlands/UU3150324001 is 107,183 bp long and has a nucleotide similarity of 98.26% to the reference Frog virus 3 isolate. Copyright © 2017 Saucedo et al.

Divergence among barking frogs (Eleutherodactylus augusti) in the southwestern United States

USGS Publications Warehouse

Goldberg, Caren S.; Sullivan, Brian K.; Malone, John H.; Schwalbe, Cecil R.

2004-01-01

Barking frogs (Eleutherodactylus augusti) are distributed from southern Mexico along the Sierra Madre Occidental into Arizona and the Sierra Madre Oriental into Texas and New Mexico. Barking frogs in Arizona and most of Texas live in rocky areas in oak woodland, while those in New Mexico and far western Texas live in rodent burrows in desertscrub. Barking frogs in each of the three states have distinct coloration and differ in sexually dimorphic characters, female vocalization, and skin toxicity. We analyzed advertisement call variation and conducted a phylogenetic analysis using mitochondrial DNA sequences (ND2 and tRNA regions) for barking frogs from these three states. Advertisement calls of frogs from Arizona were significantly longer in duration, higher in frequency, and had longer duration pulses than those of frogs from either New Mexico or Texas; frogs from these latter two sites were indistinguishable in these call variables. Phylogenetic analysis showed deep divisions among barking frogs from the three states. Differences in call structure, coloration, and mitochondrial DNA sequences strongly suggest that barking frogs in Arizona are reproductively isolated from those in New Mexico and Texas. Our results indicate that either northern populations are connected via gene flow through southern Mexico (i.e., they are subspecies as currently recognized), or represent independent lineages as originally described (i.e., western barking frogs, E. cactorum in AZ, and the eastern barking frogs, E. latrans in NM, TX).

Effects of CFT Legumine (5% Rotenone) on tadpole survival and metamorphosis of Chiricahua leopard frogs Lithobates chiricahuensis, Northern leopard frogs L. pipiens, and American bullfrogs L. catesbeianus

USGS Publications Warehouse

Alvarez, Guillermo; Caldwell, Colleen A.; Kruse, Carter G.

2017-01-01

Amphibians may experience collateral effects if exposed to CFT Legumine (5% rotenone), a piscicide that is used to remove invasive fish. A series of 48-h static toxicity tests assessed the acute effects of CFT Legumine on multi-aged tadpoles of the federally listed Chiricahua leopard frog Lithobates chiricahuensis, the widespread northern leopard frog L. pipiens, and the increasingly invasive American bullfrog L. catesbeianus. At the earliest Gosner stages (GS 21–25), Chiricahua leopard frogs were more sensitive to CFT Legumine (median lethal concentration [LC50] = 0.41–0.58 mg/L) than American bullfrogs (LC50 = 0.63–0.69 mg/L) and northern leopard frogs (LC50 = 0.91 and 1.17 mg/L). As tadpoles developed (i.e., increase in GS), their sensitivity to rotenone decreased. In a separate series of 48-h static nonrenewal toxicity tests, tadpoles (GS 21–25 and GS 31–36) of all three species were exposed to piscicidal concentrations of CFT Legumine (0.5, 1.0, and 2.0 mg/L) to assess postexposure effects on metamorphosis. In survivors of all three species at both life stages, the time to tail resorption was nearly doubled in comparison with that of controls. For example, mid-age (GS 31–36) Chiricahua leopard frog tadpoles required 210.7 h to complete tail resorption, whereas controls required 108.5 h. However, because tail resorption is a relatively short period in metamorphosis, the total duration of development (days from posthatch to complete metamorphosis) and the final weight did not differ in either age-group surviving nominal concentrations of 0.5-, 1.0-, and 2.0-mg/L CFT Legumine relative to controls. This research demonstrates that the CFT Legumine concentrations commonly used in field applications to remove unwanted fish could result in considerable mortality of the earliest stages of Lithobates species. In addition to acute lethality, piscicide treatments may result in delayed tail resorption, which places the tadpoles at risk by increasing their vulnerability to predation and pathogens.

Ant and Mite Diversity Drives Toxin Variation in the Little Devil Poison Frog.

PubMed

McGugan, Jenna R; Byrd, Gary D; Roland, Alexandre B; Caty, Stephanie N; Kabir, Nisha; Tapia, Elicio E; Trauger, Sunia A; Coloma, Luis A; O'Connell, Lauren A

2016-06-01

Poison frogs sequester chemical defenses from arthropod prey, although the details of how arthropod diversity contributes to variation in poison frog toxins remains unclear. We characterized skin alkaloid profiles in the Little Devil poison frog, Oophaga sylvatica (Dendrobatidae), across three populations in northwestern Ecuador. Using gas chromatography/mass spectrometry, we identified histrionicotoxins, 3,5- and 5,8-disubstituted indolizidines, decahydroquinolines, and lehmizidines as the primary alkaloid toxins in these O. sylvatica populations. Frog skin alkaloid composition varied along a geographical gradient following population distribution in a principal component analysis. We also characterized diversity in arthropods isolated from frog stomach contents and confirmed that O. sylvatica specialize on ants and mites. To test the hypothesis that poison frog toxin variability reflects species and chemical diversity in arthropod prey, we (1) used sequencing of cytochrome oxidase 1 to identify individual prey specimens, and (2) used liquid chromatography/mass spectrometry to chemically profile consumed ants and mites. We identified 45 ants and 9 mites in frog stomachs, including several undescribed species. We also showed that chemical profiles of consumed ants and mites cluster by frog population, suggesting different frog populations have access to chemically distinct prey. Finally, by comparing chemical profiles of frog skin and isolated prey items, we traced the arthropod source of four poison frog alkaloids, including 3,5- and 5,8-disubstituted indolizidines and a lehmizidine alkaloid. Together, the data show that toxin variability in O. sylvatica reflects chemical diversity in arthropod prey.

Regulation of early Xenopus development by ErbB signaling

PubMed Central

Nie, Shuyi; Chang, Chenbei

2008-01-01

ErbB signaling has long been implicated in cancer formation and progression and is shown to regulate cell division, migration and death during tumorigenesis. The functions of the ErbB pathway during early vertebrate embryogenesis, however, are not well understood. Here we report characterization of ErbB activities during early frog development. Gain-of-function analyses show that EGFR, ErbB2 and ErbB4 induce ectopic tumor-like cell mass that contains increased numbers of mitotic cells. Both the muscle and the neural markers are expressed in these ectopic protrusions. ErbBs also induce mesodermal markers in ectodermal explants. Loss-of-function studies using carboxyl terminal-truncated dominant-negative ErbB receptors demonstrate that blocking ErbB signals leads to defective gastrulation movements and malformation of the embryonic axis with a reduction in the head structures in early frog embryos. These data, together with the observation that ErbBs are expressed early during frog embryogenesis, suggest that ErbBs regulate cell proliferation, movements and embryonic patterning during early Xenopus development. PMID:16258939

Whole-genome sequence of the Tibetan frog Nanorana parkeri and the comparative evolution of tetrapod genomes.

PubMed

Sun, Yan-Bo; Xiong, Zi-Jun; Xiang, Xue-Yan; Liu, Shi-Ping; Zhou, Wei-Wei; Tu, Xiao-Long; Zhong, Li; Wang, Lu; Wu, Dong-Dong; Zhang, Bao-Lin; Zhu, Chun-Ling; Yang, Min-Min; Chen, Hong-Man; Li, Fang; Zhou, Long; Feng, Shao-Hong; Huang, Chao; Zhang, Guo-Jie; Irwin, David; Hillis, David M; Murphy, Robert W; Yang, Huan-Ming; Che, Jing; Wang, Jun; Zhang, Ya-Ping

2015-03-17

The development of efficient sequencing techniques has resulted in large numbers of genomes being available for evolutionary studies. However, only one genome is available for all amphibians, that of Xenopus tropicalis, which is distantly related from the majority of frogs. More than 96% of frogs belong to the Neobatrachia, and no genome exists for this group. This dearth of amphibian genomes greatly restricts genomic studies of amphibians and, more generally, our understanding of tetrapod genome evolution. To fill this gap, we provide the de novo genome of a Tibetan Plateau frog, Nanorana parkeri, and compare it to that of X. tropicalis and other vertebrates. This genome encodes more than 20,000 protein-coding genes, a number similar to that of Xenopus. Although the genome size of Nanorana is considerably larger than that of Xenopus (2.3 vs. 1.5 Gb), most of the difference is due to the respective number of transposable elements in the two genomes. The two frogs exhibit considerable conserved whole-genome synteny despite having diverged approximately 266 Ma, indicating a slow rate of DNA structural evolution in anurans. Multigenome synteny blocks further show that amphibians have fewer interchromosomal rearrangements than mammals but have a comparable rate of intrachromosomal rearrangements. Our analysis also identifies 11 Mb of anuran-specific highly conserved elements that will be useful for comparative genomic analyses of frogs. The Nanorana genome offers an improved understanding of evolution of tetrapod genomes and also provides a genomic reference for other evolutionary studies.

49 CFR 213.355 - Frog guard rails and guard faces; gage.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Frog guard rails and guard faces; gage. 213.355... Higher § 213.355 Frog guard rails and guard faces; gage. The guard check and guard face gages in frogs... distance between the gage line of a frog to the guard line 1 of its guard rail or guarding face, measured...

49 CFR 213.355 - Frog guard rails and guard faces; gage.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 4 2012-10-01 2012-10-01 false Frog guard rails and guard faces; gage. 213.355... Higher § 213.355 Frog guard rails and guard faces; gage. The guard check and guard face gages in frogs... distance between the gage line of a frog to the guard line 1 of its guard rail or guarding face, measured...

49 CFR 213.355 - Frog guard rails and guard faces; gage.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 4 2013-10-01 2013-10-01 false Frog guard rails and guard faces; gage. 213.355... Higher § 213.355 Frog guard rails and guard faces; gage. The guard check and guard face gages in frogs... distance between the gage line of a frog to the guard line 1 of its guard rail or guarding face, measured...

49 CFR 213.355 - Frog guard rails and guard faces; gage.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Frog guard rails and guard faces; gage. 213.355... Higher § 213.355 Frog guard rails and guard faces; gage. The guard check and guard face gages in frogs... distance between the gage line of a frog to the guard line 1 of its guard rail or guarding face, measured...

49 CFR 213.355 - Frog guard rails and guard faces; gage.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Frog guard rails and guard faces; gage. 213.355... Higher § 213.355 Frog guard rails and guard faces; gage. The guard check and guard face gages in frogs... distance between the gage line of a frog to the guard line 1 of its guard rail or guarding face, measured...

Frog eat frog: exploring variables influencing anurophagy.

PubMed

Measey, G John; Vimercati, Giovanni; de Villiers, F André; Mokhatla, Mohlamatsane M; Davies, Sarah J; Edwards, Shelley; Altwegg, Res

2015-01-01

Background. Frogs are generalist predators of a wide range of typically small prey items. But descriptions of dietary items regularly include other anurans, such that frogs are considered to be among the most important of anuran predators. However, the only existing hypothesis for the inclusion of anurans in the diet of post-metamorphic frogs postulates that it happens more often in bigger frogs. Moreover, this hypothesis has yet to be tested. Methods. We reviewed the literature on frog diet in order to test the size hypothesis and determine whether there are other putative explanations for anurans in the diet of post-metamorphic frogs. In addition to size, we recorded the habitat, the number of other sympatric anuran species, and whether or not the population was invasive. We controlled for taxonomic bias by including the superfamily in our analysis. Results. Around one fifth of the 355 records included anurans as dietary items of populations studied, suggesting that frogs eating anurans is not unusual. Our data showed a clear taxonomic bias with ranids and pipids having a higher proportion of anuran prey than other superfamilies. Accounting for this taxonomic bias, we found that size in addition to being invasive, local anuran diversity, and habitat produced a model that best fitted our data. Large invasive frogs that live in forests with high anuran diversity are most likely to have a higher proportion of anurans in their diet. Conclusions. We confirm the validity of the size hypothesis for anurophagy, but show that there are additional significant variables. The circumstances under which frogs eat frogs are likely to be complex, but our data may help to alert conservationists to the possible dangers of invading frogs entering areas with threatened anuran species.

Frog eat frog: exploring variables influencing anurophagy

PubMed Central

Vimercati, Giovanni; de Villiers, F. André; Mokhatla, Mohlamatsane M.; Davies, Sarah J.; Edwards, Shelley; Altwegg, Res

2015-01-01

Background. Frogs are generalist predators of a wide range of typically small prey items. But descriptions of dietary items regularly include other anurans, such that frogs are considered to be among the most important of anuran predators. However, the only existing hypothesis for the inclusion of anurans in the diet of post-metamorphic frogs postulates that it happens more often in bigger frogs. Moreover, this hypothesis has yet to be tested. Methods. We reviewed the literature on frog diet in order to test the size hypothesis and determine whether there are other putative explanations for anurans in the diet of post-metamorphic frogs. In addition to size, we recorded the habitat, the number of other sympatric anuran species, and whether or not the population was invasive. We controlled for taxonomic bias by including the superfamily in our analysis. Results. Around one fifth of the 355 records included anurans as dietary items of populations studied, suggesting that frogs eating anurans is not unusual. Our data showed a clear taxonomic bias with ranids and pipids having a higher proportion of anuran prey than other superfamilies. Accounting for this taxonomic bias, we found that size in addition to being invasive, local anuran diversity, and habitat produced a model that best fitted our data. Large invasive frogs that live in forests with high anuran diversity are most likely to have a higher proportion of anurans in their diet. Conclusions. We confirm the validity of the size hypothesis for anurophagy, but show that there are additional significant variables. The circumstances under which frogs eat frogs are likely to be complex, but our data may help to alert conservationists to the possible dangers of invading frogs entering areas with threatened anuran species. PMID:26336644

Honors for the Virtual Frog Dissection Kit

Science.gov Websites

Honors for the Virtual Frog Dissection Kit Study Web The dissection kit received a StudyWeb award Frog Project | Virtual Frog Page last modified: 01/23/05 Contacts: Bill Johnston, David Robertson

Leaping lopsided: a review of the current hypotheses regarding etiologies of limb malformations in frogs.

PubMed

Loeffler, I K; Stocum, D L; Fallon, J F; Meteyer, C U

2001-10-15

Recent progress in the investigation of limb malformations in free-living frogs has underlined the wide range in the types of limb malformations and the apparent spatiotemporal clustering of their occurrence. Here, we review the current understanding of normal and abnormal vertebrate limb development and regeneration and discuss some of the molecular events that may bring about limb malformation. Consideration of the differences between limb development and regeneration in amphibians has led us to the hypothesis that some of the observed limb malformations come about through misdirected regeneration. We report the results of a pilot study that supports this hypothesis. In this study, the distal aspect of the right hindlimb buds of X. laevis tadpoles was amputated at the pre-foot paddle stage. The tadpoles were raised in water from a pond in Minnesota at which 7% of surveyed newly metamorphosed feral frogs had malformations. Six percent (6 of 100) of the right limbs of the tadpoles raised in pond water developed abnormally. One truncated right limb was the only malformation in the control group, which was raised in dechlorinated municipal water. All unamputated limbs developed normally in both groups. Three major factors under consideration for effecting the limb malformations are discussed. These factors include environmental chemicals (primarily agrichemicals), encysted larvae (metacercariae) of trematode parasites, and increased levels of ultraviolet light. Emphasis is placed on the necessary intersection of environmental stressors and developmental events to bring about the specific malformations that are observed in free-living frog populations.

Leaping lopsided: a review of the current hypotheses regarding etiologies of limb malformations in frogs

USGS Publications Warehouse

Loeffler, I.K.; Stocum, D.L.; Fallon, J.F.; Meteyer, C.U.

2001-01-01

Recent progress in the investigation of limb malformations in free-living frogs has underlined the wide range in the types of limb malformations and the apparent spatiotemporal clustering of their occurrence. Here, we review the current understanding of normal and abnormal vertebrate limb development and regeneration and discuss some of the molecular events that may bring about limb malformation. Consideration of the differences between limb development and regeneration in amphibians has led us to the hypothesis that some of the observed limb malformations come about through misdirected regeneration. We report the results of a pilot study that supports this hypothesis. In this study, the distal aspect of the right hindlimb buds of X. laevis tadpoles was amputated at the pre-foot paddle stage. The tadpoles were raised in water from a pond in Minnesota at which 7% of surveyed newly metamorphosed feral frogs had malformations. Six percent (6 of 100) of the right limbs of the tadpoles raised in pond water developed abnormally. One truncated right limb was the only malformation in the control group, which was raised in dechlorinated municipal water. All unamputated limbs developed normally in both groups. Three major factors under consideration for effecting the limb malformations are discussed. These factors include environmental chemicals (primarily agrichemicals), encysted larvae (metacercariae) of trematode parasites, and increased levels of ultraviolet light. Emphasis is placed on the necessary intersection of environmental stressors and developmental events to bring about the specific malformations that are observed in free-living frog populations.

Transcriptomic and macroevolutionary evidence for phenotypic uncoupling between frog life history phases

PubMed Central

Wollenberg Valero, Katharina C.; Garcia-Porta, Joan; Rodríguez, Ariel; Arias, Mónica; Shah, Abhijeet; Randrianiaina, Roger Daniel; Brown, Jason L.; Glaw, Frank; Amat, Felix; Künzel, Sven; Metzler, Dirk; Isokpehi, Raphael D.; Vences, Miguel

2017-01-01

Anuran amphibians undergo major morphological transitions during development, but the contribution of their markedly different life-history phases to macroevolution has rarely been analysed. Here we generate testable predictions for coupling versus uncoupling of phenotypic evolution of tadpole and adult life-history phases, and for the underlying expression of genes related to morphological feature formation. We test these predictions by combining evidence from gene expression in two distantly related frogs, Xenopus laevis and Mantidactylus betsileanus, with patterns of morphological evolution in the entire radiation of Madagascan mantellid frogs. Genes linked to morphological structure formation are expressed in a highly phase-specific pattern, suggesting uncoupling of phenotypic evolution across life-history phases. This gene expression pattern agrees with uncoupled rates of trait evolution among life-history phases in the mantellids, which we show to have undergone an adaptive radiation. Our results validate a prevalence of uncoupling in the evolution of tadpole and adult phenotypes of frogs. PMID:28504275

Habitat connectivity and resident shared predators determine the impact of invasive bullfrogs on native frogs in farm ponds.

PubMed

Atobe, Takashi; Osada, Yutaka; Takeda, Hayato; Kuroe, Misako; Miyashita, Tadashi

2014-07-07

Habitat connectivity is considered to have an important role on the persistence of populations in the face of habitat fragmentation, in particular, for species with conservation concern. However, it can also impose indirect negative effects on native species through the spread of invasive species. Here, we investigated direct and indirect effects of habitat connectivity on populations of invasive bullfrogs and native wrinkled frogs and how these effects are modified by the presence of common carp, a resident shared predator, in a farm pond system in Japan. The distribution pattern analysis using a hierarchical Bayesian modelling indicated that bullfrogs had negative effects on wrinkled frogs, and that these negative effects were enhanced with increasing habitat connectivity owing to the metapopulation structure of bullfrogs. The analysis also suggested that common carp mitigated these impacts, presumably owing to a top-down trophic cascade through preferential predation on bullfrog tadpoles. These presumed interspecific interactions were supported by evidence from laboratory experiments, i.e. predation by carp was more intense on bullfrog tadpoles than on wrinkled frog tadpoles owing to the difference in refuge use. Our results indicate that metacommunity perspectives could provide useful insights for establishing effective management strategies of invasive species living in patchy habitats. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Organochlorine insecticides, polychlorinated biphenyls, and metals in water, sediment, and green frogs from southwestern Michigan.

PubMed

Gillilland, C D; Summer, C L; Gillilland, M G; Kannan, K; Villeneuve, D L; Coady, K K; Muzzall, P; Mehne, C; Giesy, J P

2001-07-01

In an attempt to explain the etiology of frog deformities and population declines, many possible causative factors have been examined, including the input of synthetic chemicals into aquatic systems, where frogs spend much of their lives, including their entire developmental stages. Deformities in populations of green frogs in wetlands of southwestern Michigan that are influenced by agricultural, urban, or industrial inputs were assessed in this study. Of the 1445 green frogs (Rana clamitans) examined, only four (0.3%) exhibited morphological deformities. This deformity rate is less than the recognized background level of deformities for this species, which is approximately 1%. Concentrations of organochlorine insecticides, polychlorinated biphenyls (PCBs), and metals were determined in water, sediment, frog eggs, tadpoles, and adult green frog tissues. Concentrations of all individual organochlorine insecticides in tissue were less than 6 ng/g, wet wt. Concentrations of sigmaPCBs in tissue did not exceed 100 ng/g, wet wt. Concentrations of toxic metals were less than the limits of detection. Because no significant numbers of green frog deformities were observed in this region, it can be assumed that at these low concentrations, physical malformations in green frogs should not be observed. Significance of study. This study provides information on the incidence of deformities in green frog populations in southwestern Michigan and offers background data on chemical residues in green frogs and their environment.

Habitat use and spatial structure of a barking frog (Eleutherodactylus augusti) population in southeastern Arizona

USGS Publications Warehouse

Goldberg, C.S.; Schwalbe, C.R.

2004-01-01

Barking Frogs (Eleutherodactylus augusti) are the northernmost ranging member of the large tropical family Leptodactylidae. We investigated the ecology of this saxicolous species at the northern edge of its range in a canyon in southern Arizona. We captured 54 frogs on discontinuous rock outcrops; eight of nine females and 39 of 45 males were on limestone outcrops. The remaining frogs were closer to limestone outcrops by more than 200 m than would be expected if they were distributed randomly with respect to limestone formations. Seven of 10 frogs radio-tracked had core home ranges (50% fixed kernel) from 94 to 100% on limestone; the other three frogs did not have any part of their home range on limestone outcrops. During five years of mark-recapture efforts, no frogs were found on a different outcrop from the one where they were originally captured; no radio-tracked frogs moved between outcrops during the breeding season. We estimated that four to 20 Barking Frogs occupied each outcrop; these groups probably are connected primarily by juvenile dispersal. As an organism living at the edge of its range, Barking Frogs in Arizona may rely heavily on extensive underground areas such as those found in limestone to protect them from a physiologically challenging environment. To manage for the persistence of Barking Frogs in southern Arizona, we must identify and protect habitat patches and movement pathways among them.

Albumin Evolution in Frogs: A Test of the Evolutionary Clock Hypothesis

PubMed Central

Wallace, Donald G.; Maxson, Linda R.; Wilson, Allan C.

1971-01-01

Frogs are an ancient group compared to placental mammals. Yet, although there are about as many species of frogs as there are of mammals, zoologists consider that frogs have undergone only limited morphological divergence, while placental mammals have diversified greatly in morphology and way of life. The serum albumins of numerous frog species were compared by the quantitative microcomplement fixation technique. Frogs that are morphologically similar enough to merit taxonomic distinction at only the species level often exhibit differences in the serological properties of their albumins larger than those usually seen between mammals placed in distinct families or suborders. Thus, there seems to be a contrast between albumin evolution and evolution at the organismal level. The large differences between albumins among frogs can be explained by the hypothesis that albumin evolution has proceeded at the same rate in frogs as in mammals. PMID:5002283

Practical issues in ultrashort-laser-pulse measurement using frequency-resolved optical gating

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeLong, K.W.; Fittinghoff, D.N.; Trebino, R.

1996-07-01

The authors explore several practical experimental issues in measuring ultrashort laser pulses using the technique of frequency-resolved optical gating (FROG). They present a simple method for checking the consistency of experimentally measured FROG data with the independently measured spectrum and autocorrelation of the pulse. This method is a powerful way of discovering systematic errors in FROG experiments. They show how to determine the optimum sampling rate for FROG and show that this satisfies the Nyquist criterion for the laser pulse. They explore the low- and high-power limits to FROG and determine that femtojoule operation should be possible, while the effectsmore » of self-phase modulation limit the highest signal efficiency in FROG to 1%. They also show quantitatively that the temporal blurring due to a finite-thickness medium in single-shot geometries does not strongly limit the FROG technique. They explore the limiting time-bandwidth values that can be represented on a FROG trace of a given size. Finally, they report on a new measure of the FROG error that improves convergence in the presence of noise.« less

Terrestrial activity and conservation of adult California red-legged frogs Rana aurora draytonii in coastal forests and grasslands

USGS Publications Warehouse

Bulger, J.B.; Scott, N.J.; Seymour, R.B.

2003-01-01

The federally threatened California red-legged frog Rana aurora draytonii occupies both aquatic and terrestrial habitats in its adult life stage. The terrestrial activities of this species are not well known and require documentation to assist in the development of appropriate levels of protection under the US Endangered Species Act. We studied the terrestrial activities of radio-tagged red-legged frogs (n = 8-26) inhabiting a coastal watershed in Santa Cruz County, California, during 1997-1998. In particular, we investigated (1) the use of terrestrial habitats by non-migrating adults in relation to season, breeding chronology, and precipitation, and (2) adult migration behavior, including seasonal timing, duration, distances traveled, and the use of corridors. Non-migrating red-legged frogs occupied terrestrial habitats briefly (median = 4-6 days) following infrequent summer rains, but resided nearly continuously on land (median = 20-30 days) from the onset of the winter wet-season until breeding activities commenced 1-2 months later. All of the non-migrating frogs remained within 130 m of their aquatic site of residence (median <25 m). Intervals spent on land were again brief during mid/late winter (median = 1-4 days), despite frequent and copious rainfall. Adult migration to and from breeding sites occurred from late October through mid-May (wet season). We monitored 25 migration events between aquatic sites that were 200-2800 m apart. Short distance movements ( <300 m) were completed in 1-3 days, longer movements required up to 2 months. Most migrating frogs moved overland in approximately straight lines to target sites without apparent regard to vegetation type or topography. Riparian corridors were neither essential nor preferred as migration routes. Frogs traveling overland occurred in upland habitats as far as 500 m from water. Approximately 11-22% of the adult population was estimated to migrate to and from breeding sites annually, whereas the bulk of the adult population was resident at these sites. Adequate protection of red-legged frog populations inhabiting relatively undeveloped landscapes is liable to be achieved by retaining an array of suitable habitat elements within at least 100 m of occupied aquatic sites, and by imposing seasonal limitations on detrimental human activities occurring within this zone. Specific protections for migrating frogs are probably unwarranted in forest and rangeland environments because dispersal habitat is ubiquitous and migrating frogs are widely distributed across the landscape in space and time. Published by Elsevier Science Ltd.

78 FR 60309 - Draft Environmental Impact Statement for the Restoration of Native Species in High Elevation...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-01

... prevent the extinction of two species of mountain yellow-legged frogs (Rana muscosa and Rana sierrae; MYLF... enable the NPS to fulfill its mission and policy directives to conserve native animals, plants and...

Population genetic analysis of the recently rediscovered Hula painted frog (Latonia nigriventer) reveals high genetic diversity and low inbreeding.

PubMed

Perl, R G Bina; Geffen, Eli; Malka, Yoram; Barocas, Adi; Renan, Sharon; Vences, Miguel; Gafny, Sarig

2018-04-03

After its recent rediscovery, the Hula painted frog (Latonia nigriventer) has remained one of the world's rarest and least understood amphibian species. Together with its apparently low dispersal capability and highly disturbed niche, the low abundance of this living fossil calls for urgent conservation measures. We used 18 newly developed microsatellite loci and four different models to calculate the effective population size (N e ) of a total of 125 Hula painted frog individuals sampled at a single location. We compare the N e estimates to the estimates of potentially reproducing adults in this population (N ad ) determined through a capture-recapture study on 118 adult Hula painted frogs captured at the same site. Surprisingly, our data suggests that, despite N ad estimates of only ~234-244 and N e estimates of ~16.6-35.8, the species appears to maintain a very high genetic diversity (H O  = 0.771) and low inbreeding coefficient (F IS  = -0.018). This puzzling outcome could perhaps be explained by the hypotheses of either genetic rescue from one or more unknown Hula painted frog populations nearby or by recent admixture of genetically divergent subpopulations. Independent of which scenario is correct, the original locations of these populations still remain to be determined.

Acid precipitation studies in Colorado and Wyoming: interim report of surveys of montane amphibians and water chemistry

USGS Publications Warehouse

Corn, Paul Stephen; Stolzenburg, William; Bury, R. Bruce

1989-01-01

Acid deposition may be detrimental or stressful to native populations of wildlife. Because many species of amphibians breed in shallow ponds created by spring rains or melting snow, they may be particularly vulnerable to the effects of acidification. From 1986 to 1988, we surveyed 105 locations in the central Rocky Mountains where amphibians had been recorded previously, and we found that two species of amphibians had experiences major losses. We found the northern leopard frog (Rana pipiens) at only 4 of 33 (12%) historically known localities, and the boreal toad (Bufo boreas) was present at 10 of 59 (17%) known localities. Three other species have not suffered region-wide declines. Tiger salamanders (Ambystoma tigrinum) and wood frogs (Rana sylvatica) were present at 45% and 69% of known localities respectively, and were observed at several localities were they had not been recorded previously. Chorus frogs (Pseudacris triseriata) suffered a catastrophic decline in population size in one population monitored since 1961, but regionally, this species was observed in 36 of 56 (64%) known localities and in another 19 localities where there were no previous records. Complete water chemistry was recorded for 41 localities, and pH was measured at 110 sites in total. Acid neutralizing capacity, pH, specific conductivity, and cation concentrations were negatively correlated with elevation. However, in mountain ponds and lakes, pH was rarely less than 6.0 during the amphibian breeding season. We tested the tolerance of embryos of the four species of frogs to low pH. The LC50 pH was 4.8 for chorus frogs, 4.4-4.7 for leopard frogs, 4.4-4.5 for boreal toads, and 4.2-4.3 for wood frogs. Survival of wood frog embryos declined when exposed to aluminum concentrations of 100 µg/L or greater, but boreal toad embryos survived exposure to aluminum concentrations of 400 µg/L. Acid deposition does not appear to be a major factor in the decline of leopard frogs and boreal toads. However, we have not yet investigated effects of sublethal pH on growth and development of tadpoles. Pollution remains suspect, but other factors, including natural fluctuations in population size, may account for the observed declines.

Lenomyrmex hoelldobleri: a new ant species discovered in the stomach of the dendrobatid poison frog, Oophaga sylvatica (Funkhouser)

PubMed Central

Rabeling, Christian; Sosa-Calvo, Jeffrey; O'Connell, Lauren A.; Coloma, Luis A.; Fernández, Fernando

2016-01-01

Abstract The ant genus Lenomyrmex was recently discovered and described from mid to high elevation rainforests in southern Central and northwestern South America. Lenomyrmex currently consists of six described species, which are only rarely collected. Here, we add a new species, Lenomyrmex hoelldobleri sp. n., which was discovered in a stomach content sample of the dendrobatid frog, Oophaga sylvatica, from northwestern Ecuador. Lenomyrmex hoelldobleri can be distinguished from other species in the genus by the presence of a well-developed petiolar node, whereas in all other species the node of the petiole is ill-defined. In addition to the shape of the petiolar node, Lenomyrmex hoelldobleri can be distinguished from the morphologically similar Lenomyrmex costatus by (i) the presence of the metanotal suture, (ii) the direction of the striae on dorsum of propodeum (concentrically transverse in Lenomyrmex hoelldobleri, longitudinal in Lenomyrmex costatus), (iii) the finely striate dorsum of postpetiole, (iv) its larger size, and (v) distinctly darker coloration. We also describe the gyne of Lenomyrmex foveolatus. This collection record from northwestern Ecuador extends the geographic distribution of Lenomyrmex foveolatus 400 km south from its previous record in Colombia. A revised taxonomic key to the workers and gynes of all described Lenomyrmex species is provided. We discuss the taxonomic relationship of Lenomyrmex hoelldobleri to other species in the genus and its biology based on the limited information that is currently available. Finally, we briefly discuss the feeding ecology of dendrobatid poison frogs in the context of providing a valuable source of rarely collected and cryptic new ant species. PMID:27853401

Lenomyrmex hoelldobleri: a new ant species discovered in the stomach of the dendrobatid poison frog, Oophaga sylvatica (Funkhouser).

PubMed

Rabeling, Christian; Sosa-Calvo, Jeffrey; O'Connell, Lauren A; Coloma, Luis A; Fernández, Fernando

2016-01-01

The ant genus Lenomyrmex was recently discovered and described from mid to high elevation rainforests in southern Central and northwestern South America. Lenomyrmex currently consists of six described species, which are only rarely collected. Here, we add a new species, Lenomyrmex hoelldobleri sp. n. , which was discovered in a stomach content sample of the dendrobatid frog, Oophaga sylvatica , from northwestern Ecuador. Lenomyrmex hoelldobleri can be distinguished from other species in the genus by the presence of a well-developed petiolar node, whereas in all other species the node of the petiole is ill-defined. In addition to the shape of the petiolar node, Lenomyrmex hoelldobleri can be distinguished from the morphologically similar Lenomyrmex costatus by (i) the presence of the metanotal suture, (ii) the direction of the striae on dorsum of propodeum (concentrically transverse in Lenomyrmex hoelldobleri , longitudinal in Lenomyrmex costatus ), (iii) the finely striate dorsum of postpetiole, (iv) its larger size, and (v) distinctly darker coloration. We also describe the gyne of Lenomyrmex foveolatus . This collection record from northwestern Ecuador extends the geographic distribution of Lenomyrmex foveolatus 400 km south from its previous record in Colombia. A revised taxonomic key to the workers and gynes of all described Lenomyrmex species is provided. We discuss the taxonomic relationship of Lenomyrmex hoelldobleri to other species in the genus and its biology based on the limited information that is currently available. Finally, we briefly discuss the feeding ecology of dendrobatid poison frogs in the context of providing a valuable source of rarely collected and cryptic new ant species.

Alternatives to in vivo tests to detect endocrine disrupting chemicals (EDCs) in fish and amphibians--screening for estrogen, androgen and thyroid hormone disruption.

PubMed

Scholz, S; Renner, P; Belanger, S E; Busquet, F; Davi, R; Demeneix, B A; Denny, J S; Léonard, M; McMaster, M E; Villeneuve, D L; Embry, M R

2013-01-01

Endocrine disruption is considered a highly relevant hazard for environmental risk assessment of chemicals, plant protection products, biocides and pharmaceuticals. Therefore, screening tests with a focus on interference with estrogen, androgen, and thyroid hormone pathways in fish and amphibians have been developed. However, they use a large number of animals and short-term alternatives to animal tests would be advantageous. Therefore, the status of alternative assays for endocrine disruption in fish and frogs was assessed by a detailed literature analysis. The aim was to (i) determine the strengths and limitations of alternative assays and (ii) present conclusions regarding chemical specificity, sensitivity, and correlation with in vivo data. Data from 1995 to present were collected related to the detection/testing of estrogen-, androgen-, and thyroid-active chemicals in the following test systems: cell lines, primary cells, fish/frog embryos, yeast and cell-free systems. The review shows that the majority of alternative assays measure effects directly mediated by receptor binding or resulting from interference with hormone synthesis. Other mechanisms were rarely analysed. A database was established and used for a quantitative and comparative analysis. For example, a high correlation was observed between cell-free ligand binding and cell-based reporter cell assays, between fish and frog estrogenic data and between fish embryo tests and in vivo reproductive effects. It was concluded that there is a need for a more systematic study of the predictive capacity of alternative tests and ways to reduce inter- and intra-assay variability.

Early-life disruption of amphibian microbiota decreases later-life resistance to parasites.

PubMed

Knutie, Sarah A; Wilkinson, Christina L; Kohl, Kevin D; Rohr, Jason R

2017-07-20

Changes in the early-life microbiota of hosts might affect infectious disease risk throughout life, if such disruptions during formative times alter immune system development. Here, we test whether an early-life disruption of host-associated microbiota affects later-life resistance to infections by manipulating the microbiota of tadpoles and challenging them with parasitic gut worms as adults. We find that tadpole bacterial diversity is negatively correlated with parasite establishment in adult frogs: adult frogs that had reduced bacterial diversity as tadpoles have three times more worms than adults without their microbiota manipulated as tadpoles. In contrast, adult bacterial diversity during parasite exposure is not correlated with parasite establishment in adult frogs. Thus, in this experimental setup, an early-life disruption of the microbiota has lasting reductions on host resistance to infections, which is possibly mediated by its effects on immune system development. Our results support the idea that preventing early-life disruption of host-associated microbiota might confer protection against diseases later in life.Early-life microbiota alterations can affect infection susceptibility later in life, in animal models. Here, Knutie et al. show that manipulating the microbiota of tadpoles leads to increased susceptibility to parasitic infection in adult frogs, in the absence of substantial changes in the adults' microbiota.

Prototype next generation frog foundation - preliminary evaluation : research results.

DOT National Transportation Integrated Search

2016-06-01

Conventional wisdom suggests that a solid or rigid one-piece frog is preferred because it is easy to maintain. However, testing and subsequent modeling demonstrated that a flexible frog (i.e., a two-piece frog split in the flangeway) produced signifi...

Involvement of adrenal hormones in tissue respiration of sub-tropical hibernating and non-hibernating species of frogs.

PubMed

Gupta, B B; Mahanta, A

1997-03-01

Effects of norepinephrine (NE), epinephrine (EP), corticosterone and cortisol were studied both in vivo and in vitro on the rate of oxygen consumption of tissues (liver, skeletal muscle and kidney) of sub-tropical Indian frogs Rana limnocharis (a hibernating species) and Rana cyanophlyctis (a non-hibernating species) exposed to natural climatic conditions during winter and summer/rainy seasons. Further, the effects of NE and EP were also studied in vitro in the presence of specific beta- and alpha-adrenergic antagonists (propranolol and prazosin). NE, EP and corticosterone, when administered in vivo or in vitro, significantly stimulated the respiratory rate of the tissues of both the species irrespective of the seasons/temperature. Results suggest that NE, EP and corticosterone are directly involved in regulation of the energy metabolism of both hibernating and non-hibernating species of sub-tropical frogs. The calorigenic action of NE and EP seems to be mediated by both beta- and alpha-adrenergic receptors. However, the temporal involvement of beta- and alpha-adrenergic receptors seems to be tissue-dependent.

[Autoradiographic study of the renewal rate of neutrophils and thrombocytes in summer and winter frogs].

PubMed

Goryshina, E N

1984-04-01

In early August frogs were injected with 3H-thymidine and observed during 10 months under conditions close to natural. Individual changes of neutrophil and thrombocyte contents in the blood, those of the number of labeled cells among them, and the density of labeling were studied. The life span of neutrophils in the active frogs was found as long as 2-3 weeks, while that of thrombocytes lasted for several months. In September the hibernating cell populations are formed and cell proliferation ceases. This process is suggested to be regulated by some complex centralized mechanisms rather than by a direct action of temperature. The size of circulating populations of both the cell types decreases during hibernation, part of the cells is deposited outside of circulation. The life span of cells rises considerably, their renewal begins only in spring. The ability of cells of the neutrophilic lineage to proliferate is preserved at low temperatures and is realized in pathological conditions. The similarities in seasonal adaptations are stated between amphibians and hibernating mammals at the level of cellular populations.

Enzymatic Regulation of Glycogenolysis in a Subarctic Population of the Wood Frog: Implications for Extreme Freeze Tolerance

PubMed Central

do Amaral, M. Clara F.; Lee, Richard E.; Costanzo, Jon P.

2013-01-01

The wood frog, Rana sylvatica, from Interior Alaska survives freezing at –16°C, a temperature 10–13°C below that tolerated by its southern conspecifics. We investigated the hepatic freezing response in this northern phenotype to determine if its profound freeze tolerance is associated with an enhanced glucosic cryoprotectant system. Alaskan frogs had a larger liver glycogen reserve that was mobilized faster during early freezing as compared to conspecifics from a cool-temperate region (southern Ohio, USA). In Alaskan frogs the rapid glucose production in the first hours of freezing was associated with a 7-fold increase in glycogen phosphorylase activity above unfrozen frog levels, and the activity of this enzyme was higher than that of frozen Ohioan frogs. Freezing of Ohioan frogs induced a more modest (4-fold) increase in glycogen phosphorylase activity above unfrozen frog values. Relative to the Ohioan frogs, Alaskan frogs maintained a higher total protein kinase A activity throughout an experimental freezing/thawing time course, and this may have potentiated glycogenolysis during early freezing. We found populational variation in the activity and protein level of protein kinase A which suggested that the Alaskan population had a more efficient form of this enzyme. Alaskan frogs modulated their glycogenolytic response by decreasing the activity of glycogen phosphorylase after cryoprotectant mobilization was well under way, thereby conserving their hepatic glycogen reserve. Ohioan frogs, however, sustained high glycogen phosphorylase activity until early thawing and consumed nearly all their liver glycogen. These unique hepatic responses of Alaskan R. sylvatica likely contribute to this phenotype’s exceptional freeze tolerance, which is necessary for their survival in a subarctic climate. PMID:24236105

Effects of polychlorinated biphenyl 126 on green frog (Rana clamitans) and leopard frog (Rana pipiens) hatching success, development, and metamorphosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenshield, M.L.; Jofre, M.B.; Karasov, W.H.

1999-11-01

Although increasing evidence links plana chlorinated hydrocarbons, such as polychlorinated biphenyls (PCBs), to decreases in survival and reproduction of fish, mammals, and birds near Green Bay, Wisconsin, and the Great Lakes, USA, relatively little is known of their bioaccumulation or of their possible effects in amphibians. The authors exposed embryos and larvae of two ranid species commonly occurring in the Green Bay ecosystem, the green frog (Rana clamitans) and the leopard frog (Rana pipiens), to PCB 126, a model coplanar PCB compound. Nominal concentrations ranged from 0.005 to 50 {micro}g/L, and exposure lasted through metamorphosis. Tissue concentrations of PCB 126more » in tadpoles that did not metamorphose by the end of the experiment ranged from 1.2 to 9,600 ng/g wet mass. No significant mortality of embryos occurred before hatching; however, survival of larvae was significantly reduced at the highest concentration for both species. Few deformities were observed, but the incidence of edema was significantly higher in tadpoles exposed to 50 {micro}g/L. Swimming speed and growth of tadpoles was also significantly reduced in this treatment. The percent of tadpoles that reached metamorphosis was significantly lower in green frogs at the highest concentration, and no leopard frogs survived past day 47 of the experiment in this treatment. At high concentrations, PCB 126 affected both ranid species; however, sublethal effects were not apparent for the parameters the authors measured at concentrations that occur in water in the Green Bay ecosystem.« less

Potential therapeutic applications of multifunctional host-defense peptides from frog skin as anti-cancer, anti-viral, immunomodulatory, and anti-diabetic agents.

PubMed

Conlon, J Michael; Mechkarska, Milena; Lukic, Miodrag L; Flatt, Peter R

2014-07-01

Frog skin constitutes a rich source of peptides with a wide range of biological properties. These include host-defense peptides with cytotoxic activities against bacteria, fungi, protozoa, viruses, and mammalian cells. Several hundred such peptides from diverse species have been described. Although attention has been focused mainly on antimicrobial activity, the therapeutic potential of frog skin peptides as anti-infective agents remains to be realized and no compound based upon their structures has yet been adopted in clinical practice. Consequently, alternative applications are being explored. Certain naturally occurring frog skin peptides, and analogs with improved therapeutic properties, show selective cytotoxicity against tumor cells and viruses and so have potential for development into anti-cancer and anti-viral agents. Some peptides display complex cytokine-mediated immunomodulatory properties. Effects on the production of both pro-inflammatory and anti-inflammatory cytokines by peritoneal macrophages and peripheral blood mononuclear cells have been observed so that clinical applications as anti-inflammatory, immunosuppressive, and immunostimulatory agents are possible. Several frog skin peptides, first identified on the basis of antimicrobial activity, have been shown to stimulate insulin release both in vitro and in vivo and so show potential as incretin-based therapies for treatment of patients with Type 2 diabetes mellitus. This review assesses the therapeutic possibilities of peptides from frogs belonging to the Ascaphidae, Alytidae, Pipidae, Dicroglossidae, Leptodactylidae, Hylidae, and Ranidae families that complement their potential role as anti-infectives for use against multidrug-resistant microorganisms. Copyright © 2014 Elsevier Inc. All rights reserved.

Condition-dependent reproductive effort in frogs infected by a widespread pathogen

PubMed Central

Roznik, Elizabeth A.; Sapsford, Sarah J.; Pike, David A.; Schwarzkopf, Lin; Alford, Ross A.

2015-01-01

To minimize the negative effects of an infection on fitness, hosts can respond adaptively by altering their reproductive effort or by adjusting their timing of reproduction. We studied effects of the pathogenic fungus Batrachochytrium dendrobatidis on the probability of calling in a stream-breeding rainforest frog (Litoria rheocola). In uninfected frogs, calling probability was relatively constant across seasons and body conditions, but in infected frogs, calling probability differed among seasons (lowest in winter, highest in summer) and was strongly and positively related to body condition. Infected frogs in poor condition were up to 40% less likely to call than uninfected frogs, whereas infected frogs in good condition were up to 30% more likely to call than uninfected frogs. Our results suggest that frogs employed a pre-existing, plastic, life-history strategy in response to infection, which may have complex evolutionary implications. If infected males in good condition reproduce at rates equal to or greater than those of uninfected males, selection on factors affecting disease susceptibility may be minimal. However, because reproductive effort in infected males is positively related to body condition, there may be selection on mechanisms that limit the negative effects of infections on hosts. PMID:26063847

Assessment of radiocesium contamination in frogs 18 months after the Fukushima Daiichi nuclear disaster

PubMed Central

Matsushima, Noe; Ihara, Sadao; Takase, Minoru; Horiguchi, Toshihiro

2015-01-01

We investigated the accumulation of radionuclides in frogs inhabiting radioactively contaminated areas around Fukushima Daiichi Nuclear Power Plant (FDNPP) to search for possible adverse effects due to radionuclides. We collected 5 frog species and soil samples in areas within and outside a 20-km radius from FDNPP in August and September 2012 and determined their radiocesium concentrations (134Cs and 137Cs). There was a positive correlation between radiocesium concentrations in the soil samples and frogs, and the highest concentration in frogs was 47,278.53 Bq/kg-wet. Although we conducted a histological examination of frog ovaries and testes by light microscopy to detect possible effects of radionuclides on the morphology of germ cells, there were no clear abnormalities in the gonadal tissues of frogs collected from sites with different contamination levels. PMID:25857262

Assessment of radiocesium contamination in frogs 18 months after the Fukushima Daiichi nuclear disaster

NASA Astrophysics Data System (ADS)

Matsushima, Noe; Ihara, Sadao; Takase, Minoru; Horiguchi, Toshihiro

2015-04-01

We investigated the accumulation of radionuclides in frogs inhabiting radioactively contaminated areas around Fukushima Daiichi Nuclear Power Plant (FDNPP) to search for possible adverse effects due to radionuclides. We collected 5 frog species and soil samples in areas within and outside a 20-km radius from FDNPP in August and September 2012 and determined their radiocesium concentrations (134Cs and 137Cs). There was a positive correlation between radiocesium concentrations in the soil samples and frogs, and the highest concentration in frogs was 47,278.53 Bq/kg-wet. Although we conducted a histological examination of frog ovaries and testes by light microscopy to detect possible effects of radionuclides on the morphology of germ cells, there were no clear abnormalities in the gonadal tissues of frogs collected from sites with different contamination levels.

Assessment of radiocesium contamination in frogs 18 months after the Fukushima Daiichi nuclear disaster.

PubMed

Matsushima, Noe; Ihara, Sadao; Takase, Minoru; Horiguchi, Toshihiro

2015-04-10

We investigated the accumulation of radionuclides in frogs inhabiting radioactively contaminated areas around Fukushima Daiichi Nuclear Power Plant (FDNPP) to search for possible adverse effects due to radionuclides. We collected 5 frog species and soil samples in areas within and outside a 20-km radius from FDNPP in August and September 2012 and determined their radiocesium concentrations ((134)Cs and (137)Cs). There was a positive correlation between radiocesium concentrations in the soil samples and frogs, and the highest concentration in frogs was 47,278.53 Bq/kg-wet. Although we conducted a histological examination of frog ovaries and testes by light microscopy to detect possible effects of radionuclides on the morphology of germ cells, there were no clear abnormalities in the gonadal tissues of frogs collected from sites with different contamination levels.

Conservation in the Teaching Laboratory--Substitution of Xenopus for Rana.

ERIC Educational Resources Information Center

Bernhart, David M; And Others

1991-01-01

Reports on experimental comparisons between the leopard frog, currently captured for laboratory use, and the African clawed frog, raised specifically for research. Except for the increased longevity of isolated nerve axons in the clawed frog, no other significant differences were established. Recommends laboratory use of clawed frogs as…

Diversity within diversity: Parasite species richness in poison frogs assessed by transcriptomics.

PubMed

Santos, Juan C; Tarvin, Rebecca D; O'Connell, Lauren A; Blackburn, David C; Coloma, Luis A

2018-08-01

Symbionts (e.g., endoparasites and commensals) play an integral role in their host's ecology, yet in many cases their diversity is likely underestimated. Although endoparasites are traditionally characterized using morphology, sequences of conserved genes, and shotgun metagenomics, host transcriptomes constitute an underused resource to identify these organisms' diversity. By isolating non-host transcripts from host transcriptomes, individual host tissues can now simultaneously reveal their endoparasite species richness (i.e., number of different taxa) and provide insights into parasite gene expression. These approaches can be used in host taxa whose endoparasites are mostly unknown, such as those of tropical amphibians. Here, we focus on the poison frogs (Dendrobatidae) as hosts, which are a Neotropical clade known for their bright coloration and defensive alkaloids. These toxins are an effective protection against vertebrate predators (e.g., snakes and birds), bacteria, and skin-biting ectoparasites (e.g., mosquitoes); however, little is known about their deterrence against eukaryotic endoparasites. With de novo transcriptomes of dendrobatids, we developed a bioinformatics pipeline for endoparasite identification that uses host annotated RNA-seq data and set of a priori parasite taxonomic terms, which are used to mine for specific endoparasites. We found a large community of helminths and protozoans that were mostly restricted to the digestive tract and a few systemic parasites (e.g., Trypanosoma). Contrary to our expectations, all dendrobatid frogs regardless of the presence of alkaloid defenses have endoparasites, with their highest species richness located in the frog digestive tract. Some of these organisms (e.g., roundworms) might prove to be generalists, as they were not found to be co-diversifying with their frog hosts. We propose that endoparasites may escape poison frogs' chemical defenses by colonizing tissues with fewer alkaloids than the frog's skin, where most toxins are stored. Copyright © 2018 Elsevier Inc. All rights reserved.

Environmental Assessment of Installation Development at Dover Air Force Base, Delaware

DTIC Science & Technology

2007-09-01

matter equal or less than 10 microns in diameter PM2.5 particulate matter equal or less than 2.5 microns in diameter PMP Pest Management Plan POL...migrants), and 9 species of butterflies. Pest species include mosquitoes (Family: Culcidae), groundhog (Marmota monax), skunk (Mephitis mephitis), fox...frog-fruit (Phyla lanceolata), and hyssop-leaf hedge- nettle (Stachys hyssopifolia); however, the green frog-fruit and the hyssop-leaf hedge- nettle are

DEVELOPMENTAL DIVERSITY OF AMPHIBIANS

PubMed Central

Elinson, Richard P.; del Pino, Eugenia M.

2011-01-01

The current model amphibian, Xenopus laevis, develops rapidly in water to a tadpole which metamorphoses into a frog. Many amphibians deviate from the X. laevis developmental pattern. Among other adaptations, their embryos develop in foam nests on land or in pouches on their mother’s back or on a leaf guarded by a parent. The diversity of developmental patterns includes multinucleated oogenesis, lack of RNA localization, huge non-pigmented eggs, and asynchronous, irregular early cleavages. Variations in patterns of gastrulation highlight the modularity of this critical developmental period. Many species have eliminated the larva or tadpole and directly develop to the adult. The wealth of developmental diversity among amphibians coupled with the wealth of mechanistic information from X. laevis permit comparisons that provide deeper insights into developmental processes. PMID:22662314

Boric Acid Is Reproductively Toxic to Adult Xenopus laevis, but Not Endocrine Active.

PubMed

Fort, Douglas J; Fort, Troy D; Mathis, Michael B; Ball, R Wayne

2016-11-01

The potential reproductive and endocrine toxicity of boric acid (BA) in the African clawed frog, Xenopus laevis, was evaluated using a 30-day exposure of adult frogs. Adult female and male frogs established as breeders were exposed to a culture water control and 4 target (nominal) test concentrations [5.0, 7.5, 10.0, and 15 mg boron (B)/L, equivalent to 28.5, 42.8, 57.0, and 85.5 mg BA/L] using flow-through diluter exposure system. The primary endpoints measured were adult survival, growth (weight and snout-vent length [SVL]), necropsy data, reproductive fecundity, and development of progeny (F1) from the exposed frogs. Necropsy endpoints included gonad weight, gonado-somatic index (GSI), ovary profile (oocyte normalcy and stage distribution), sperm count, and dysmorphology. Endocrine endpoints included plasma estradiol (E2), testosterone (T), dihydrotestosteone (DHT), gonadal CYP 19 (aromatase), and gonadal 5α-reductase (5-AR). BA exposure to adult female X. laevis increased the proportion of immature oocytes (< stage II) in the ovaries of females, reduced sperm counts and increased sperm cell dysmorphology frequency in male frogs exposed to 15 mg B/L. No effects on the other general, developmental (F1), or endocrine endpoints were observed. Based on the results of the present study, the no observed adverse effects concentration (NOAEC) for the reproductive endpoints was 10 mg B/L; and 15 mg B/L for reproductive fecundity, F1 embryo larval development, and endocrine function. These results confirmed that although BA is capable of inducing reproductive toxicity at high concentrations, it is not an endocrine disrupting agent. © The Author 2016. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

A general algorithm using finite element method for aerodynamic configurations at low speeds

NASA Technical Reports Server (NTRS)

Balasubramanian, R.

1975-01-01

A finite element algorithm for numerical simulation of two-dimensional, incompressible, viscous flows was developed. The Navier-Stokes equations are suitably modelled to facilitate direct solution for the essential flow parameters. A leap-frog time differencing and Galerkin minimization of these model equations yields the finite element algorithm. The finite elements are triangular with bicubic shape functions approximating the solution space. The finite element matrices are unsymmetrically banded to facilitate savings in storage. An unsymmetric L-U decomposition is performed on the finite element matrices to obtain the solution for the boundary value problem.

Strategies for assessing the implications of malformed frogs for environmental health.

PubMed Central

Burkhart, J G; Ankley, G; Bell, H; Carpenter, H; Fort, D; Gardiner, D; Gardner, H; Hale, R; Helgen, J C; Jepson, P; Johnson, D; Lannoo, M; Lee, D; Lary, J; Levey, R; Magner, J; Meteyer, C; Shelby, M D; Lucier, G

2000-01-01

The recent increase in the incidence of deformities among natural frog populations has raised concern about the state of the environment and the possible impact of unidentified causative agents on the health of wildlife and human populations. An open workshop on Strategies for Assessing the Implications of Malformed Frogs for Environmental Health was convened on 4-5 December 1997 at the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina. The purpose of the workshop was to share information among a multidisciplinary group with scientific interest and responsibility for human and environmental health at the federal and state level. Discussions highlighted possible causes and recent findings directly related to frog deformities and provided insight into problems and strategies applicable to continuing investigation in several areas. Possible causes of the deformities were evaluated in terms of diagnostics performed on field amphibians, biologic mechanisms that can lead to the types of malformations observed, and parallel laboratory and field studies. Hydrogeochemistry must be more integrated into environmental toxicology because of the pivotal role of the aquatic environment and the importance of fates and transport relative to any potential exposure. There is no indication of whether there may be a human health factor associated with the deformities. However, the possibility that causal agents may be waterborne indicates a need to identify the relevant factors and establish the relationship between environmental and human health in terms of hazard assessment. PMID:10620528

Diversification of rhacophorid frogs provides evidence for accelerated faunal exchange between India and Eurasia during the Oligocene.

PubMed

Li, Jia-Tang; Li, Yang; Klaus, Sebastian; Rao, Ding-Qi; Hillis, David M; Zhang, Ya-Ping

2013-02-26

The accretion of the Indian subcontinent to Eurasia triggered a massive faunal and floral exchange, with Gondwanan taxa entering into Asia and vice versa. The traditional view on the Indian-Asian collision assumes contact of the continental plates during the Early Eocene. Many biogeographic studies rely on this assumption. However, the exact mode and timing of this geological event is still under debate. Here we address, based on an extensive phylogenetic analysis of rhacophorid tree frogs, if there was already a Paleogene biogeographic link between Southeast Asia and India; in which direction faunal exchange occurred between India and Eurasia within the Rhacophoridae; and if the timing of the faunal exchange correlates with one of the recently suggested geological models. Rhacophorid tree frogs showed an early dispersal from India to Asia between 46 and 57 Ma, as reconstructed from the fossil record. During the Middle Eocene, however, faunal exchange ceased, followed by increase of rhacophorid dispersal events between Asia and the Indian subcontinent during the Oligocene that continued until the Middle Miocene. This corroborates recent geological models that argue for a much later final collision between the continental plates. We predict that the Oligocene faunal exchange between the Indian subcontinent and Asia, as shown here for rhacophorid frogs, also applies for other nonvolant organisms with an Indian-Asian distribution, and suggest that previous studies that deal with this faunal interchange should be carefully reinvestigated.

Diversification of rhacophorid frogs provides evidence for accelerated faunal exchange between India and Eurasia during the Oligocene

PubMed Central

Li, Jia-Tang; Li, Yang; Klaus, Sebastian; Rao, Ding-Qi; Hillis, David M.; Zhang, Ya-Ping

2013-01-01

The accretion of the Indian subcontinent to Eurasia triggered a massive faunal and floral exchange, with Gondwanan taxa entering into Asia and vice versa. The traditional view on the Indian–Asian collision assumes contact of the continental plates during the Early Eocene. Many biogeographic studies rely on this assumption. However, the exact mode and timing of this geological event is still under debate. Here we address, based on an extensive phylogenetic analysis of rhacophorid tree frogs, if there was already a Paleogene biogeographic link between Southeast Asia and India; in which direction faunal exchange occurred between India and Eurasia within the Rhacophoridae; and if the timing of the faunal exchange correlates with one of the recently suggested geological models. Rhacophorid tree frogs showed an early dispersal from India to Asia between 46 and 57 Ma, as reconstructed from the fossil record. During the Middle Eocene, however, faunal exchange ceased, followed by increase of rhacophorid dispersal events between Asia and the Indian subcontinent during the Oligocene that continued until the Middle Miocene. This corroborates recent geological models that argue for a much later final collision between the continental plates. We predict that the Oligocene faunal exchange between the Indian subcontinent and Asia, as shown here for rhacophorid frogs, also applies for other nonvolant organisms with an Indian–Asian distribution, and suggest that previous studies that deal with this faunal interchange should be carefully reinvestigated. PMID:23401521

Field evidence for linking Altosid applications with increased amphibian deformities in southern leopard frogs [abstract

USGS Publications Warehouse

Sparling, D.W.

1998-01-01

During the summer of 1997 we repeatedly sprayed Altosid, a formulation of 4% methoprene used for mosquito control, on six constructed macrocosms. Six additional macrocosms were sprayed with Abate4E, containing the organophosphate pesticide temephos, and six were sprayed with water (controls). The wetlands were created on an impermeable foundation for research purposes and averaged 215 m2 in area and 0.5 m deep. Application rates and frequency of Abate4E and Altosid followed label directions and mimicked procedures for mosquito control in National Wildlife Refuges. In early September juvenile frogs and metamorphing tadpoles were collected with dip nets from each pond and examined for deformities. In all, 91 juveniles and metamorph southern leopard frogs (Rana utricularia) were collected from Altosid sprayed wetlands with 14 (15%) demonstrating deformities. Seventyseven juveniles and metamorphs were collected from control wetlands with three (4%) showing deformities. Only six juveniles and metamorphs were collected from Abate4E wetlands and none showed deformities. Deformities included missing or deformed hind limbs (9 of 10 involving only the right hind limb), missing eyes, and abnormal color. The differences in rate of deformities was dependent on treatment (X2=6.44, p< 0.02). The number of leopard frogs caught per unit effort (tadpoles and juveniles) differed among treatments (p=0.032) with Abate4E wetlands producing fewer individuals per capture effort than either Altosid or control wetlands.

A low-dispersion, exactly energy-charge-conserving semi-implicit relativistic particle-in-cell algorithm

NASA Astrophysics Data System (ADS)

Chen, Guangye; Luis, Chacon; Bird, Robert; Stark, David; Yin, Lin; Albright, Brian

2017-10-01

Leap-frog based explicit algorithms, either ``energy-conserving'' or ``momentum-conserving'', do not conserve energy discretely. Time-centered fully implicit algorithms can conserve discrete energy exactly, but introduce large dispersion errors in the light-wave modes, regardless of timestep sizes. This can lead to intolerable simulation errors where highly accurate light propagation is needed (e.g. laser-plasma interactions, LPI). In this study, we selectively combine the leap-frog and Crank-Nicolson methods to produce a low-dispersion, exactly energy-and-charge-conserving PIC algorithm. Specifically, we employ the leap-frog method for Maxwell equations, and the Crank-Nicolson method for particle equations. Such an algorithm admits exact global energy conservation, exact local charge conservation, and preserves the dispersion properties of the leap-frog method for the light wave. The algorithm has been implemented in a code named iVPIC, based on the VPIC code developed at LANL. We will present numerical results that demonstrate the properties of the scheme with sample test problems (e.g. Weibel instability run for 107 timesteps, and LPI applications.

Nematode and ciliate nasal infection in captive archey's frogs (Leiopelma archeyi).

PubMed

Shaw, Stephanie; Speare, Richard; Lynn, Denis H; Yeates, Gregor; Zhao, Zeng; Berger, Lee; Jakob-Hoff, Richard

2011-09-01

Archey's frogs (Leiopelma archeyi) are first on the list of evolutionarily distinct and globally endangered (EDGE) amphibians. Captive breeding is an important strategy for protection of the species, but programs are hampered by a lack of information on diseases present in wild and captive populations. Two novel nematodes (Koerneria sp. and Rhabditis sp.) were found separately in four captive Archey's frogs showing clinical signs of hemorrhagic purulent nasal discharge and weight loss. One of these frogs also had a novel protozoal infection (Tetrahymena) in the nasal cavity. Koerneria, Rhabditis, and Tetrahymena have not previously been reported in amphibians in New Zealand. One frog was treated successfully with oral moxidectin at 0.4 mg/kg for the nematode infection and topical metronidazole at 10 mg/kg for the protozoal infection. The clinical signs abated only after both infections were cleared. The second frog died before treatment could be established. The third and fourth frogs were found dead.

49 CFR 236.327 - Switch, movable-point frog or split-point derail.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Switch, movable-point frog or split-point derail..., AND APPLIANCES Interlocking Rules and Instructions § 236.327 Switch, movable-point frog or split-point derail. Switch, movable-point frog, or split-point derail equipped with lock rod shall be maintained so...

49 CFR 236.327 - Switch, movable-point frog or split-point derail.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 4 2012-10-01 2012-10-01 false Switch, movable-point frog or split-point derail..., AND APPLIANCES Interlocking Rules and Instructions § 236.327 Switch, movable-point frog or split-point derail. Switch, movable-point frog, or split-point derail equipped with lock rod shall be maintained so...

49 CFR 236.327 - Switch, movable-point frog or split-point derail.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 4 2013-10-01 2013-10-01 false Switch, movable-point frog or split-point derail..., AND APPLIANCES Interlocking Rules and Instructions § 236.327 Switch, movable-point frog or split-point derail. Switch, movable-point frog, or split-point derail equipped with lock rod shall be maintained so...

49 CFR 236.327 - Switch, movable-point frog or split-point derail.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Switch, movable-point frog or split-point derail..., AND APPLIANCES Interlocking Rules and Instructions § 236.327 Switch, movable-point frog or split-point derail. Switch, movable-point frog, or split-point derail equipped with lock rod shall be maintained so...

49 CFR 236.327 - Switch, movable-point frog or split-point derail.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Switch, movable-point frog or split-point derail..., AND APPLIANCES Interlocking Rules and Instructions § 236.327 Switch, movable-point frog or split-point derail. Switch, movable-point frog, or split-point derail equipped with lock rod shall be maintained so...

A regional survey of malformed frogs in Minnesota (USA) (Minnesota malformed frogs).

PubMed

Vandenlangenberg, Susan M; Canfield, Jeffrey T; Magner, Joseph A

2003-02-01

In late 1995, school children discovered malformed frogs in a south central Minnesota pond. Press coverage resulted in numerous citizen reports of frog malformation across Minnesota in 1996. After some initial site investigation, 3 affected frog sites and 4 nearby reference sites were selected for more detailed evaluation. Field biologists made 89 visits to study sites beginning spring 1997 through fall 1999 to examine the number and type of frog malformations. Over 5,100 Leopard frogs (Rana pipiens) were captured and examined at all study sites. Water elevations and associated littoral inundation were recorded from 1997-2000. Results indicate that malformation occurred at all study sites above historical background levels. Rana pipiens malformation across all sites over three seasons averaged 7.9% and ranged from 0 to 7% at reference sites and 4 to 23% at affected sites. At one northern Minnesota site, mink frog (Rana septentrionalis) malformation was 75% in 1998. A site characteristic common to the most affected sites was an elastic zone of littoral inundation. Climate driven hydrologic variation likely influenced water depth and associated breeding locations.

The Genome of the Western Clawed Frog Xenopus tropicalis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hellsten, Uffe; Harland, Richard M.; Gilchrist, Michael J.

2009-10-01

The western clawed frog Xenopus tropicalis is an important model for vertebrate development that combines experimental advantages of the African clawed frog Xenopus laevis with more tractable genetics. Here we present a draft genome sequence assembly of X. tropicalis. This genome encodes over 20,000 protein-coding genes, including orthologs of at least 1,700 human disease genes. Over a million expressed sequence tags validated the annotation. More than one-third of the genome consists of transposable elements, with unusually prevalent DNA transposons. Like other tetrapods, the genome contains gene deserts enriched for conserved non-coding elements. The genome exhibits remarkable shared synteny with humanmore » and chicken over major parts of large chromosomes, broken by lineage-specific chromosome fusions and fissions, mainly in the mammalian lineage.« less

Design and Dynamic Model of a Frog-inspired Swimming Robot Powered by Pneumatic Muscles

NASA Astrophysics Data System (ADS)

Fan, Ji-Zhuang; Zhang, Wei; Kong, Peng-Cheng; Cai, He-Gao; Liu, Gang-Feng

2017-09-01

Pneumatic muscles with similar characteristics to biological muscles have been widely used in robots, and thus are promising drivers for frog inspired robots. However, the application and nonlinearity of the pneumatic system limit the advance. On the basis of the swimming mechanism of the frog, a frog-inspired robot based on pneumatic muscles is developed. To realize the independent tasks by the robot, a pneumatic system with internal chambers, micro air pump, and valves is implemented. The micro pump is used to maintain the pressure difference between the source and exhaust chambers. The pneumatic muscles are controlled by high-speed switch valves which can reduce the robot cost, volume, and mass. A dynamic model of the pneumatic system is established for the simulation to estimate the system, including the chamber, muscle, and pneumatic circuit models. The robot design is verified by the robot swimming experiments and the dynamic model is verified through the experiments and simulations of the pneumatic system. The simulation results are compared to analyze the functions of the source pressure, internal volume of the muscle, and circuit flow rate which is proved the main factor that limits the response of muscle pressure. The proposed research provides the application of the pneumatic muscles in the frog inspired robot and the pneumatic model to study muscle controller.

Dietary alkaloid sequestration in a poison frog: an experimental test of alkaloid uptake in Melanophryniscus stelzneri (Bufonidae).

PubMed

Hantak, Maggie M; Grant, Taran; Reinsch, Sherri; McGinnity, Dale; Loring, Marjorie; Toyooka, Naoki; Saporito, Ralph A

2013-12-01

Several lineages of brightly colored anurans independently evolved the ability to secrete alkaloid-containing defensive chemicals from granular glands in the skin. These species, collectively referred to as 'poison frogs,' form a polyphyletic assemblage that includes some species of Dendrobatidae, Mantellidae, Myobatrachidae, Bufonidae, and Eleutherodactylidae. The ability to sequester alkaloids from dietary arthropods has been demonstrated experimentally in most poison frog lineages but not in bufonid or eleutherodactylid poison frogs. As with other poison frogs, species of the genus Melanophryniscus (Bufonidae) consume large numbers of mites and ants, suggesting they might also sequester defensive alkaloids from dietary sources. To test this hypothesis, fruit flies dusted with alkaloid/nutritional supplement powder were fed to individual Melanophryniscus stelzneri in two experiments. In the first experiment, the alkaloids 5,8-disubstituted indolizidine 235B' and decahydroquinoline were administered to three individuals for 104 days. In the second experiment, the alkaloids 3,5-disubstituted indolizidine 239Q and decahydroquinoline were given to three frogs for 153 days. Control frogs were fed fruit flies dusted only with nutritional supplement. Gas chromatography/mass spectrometry analyses revealed that skin secretions of all experimental frogs contained alkaloids, whereas those of all control frogs lacked alkaloids. Uptake of decahydroquinoline was greater than uptake of 5,8-disubstituted indolizidine, and uptake of 3,5-disubstituted indolizidine was greater than uptake of decahydroquinoline, suggesting greater uptake efficiency of certain alkaloids. Frogs in the second experiment accumulated a greater amount of alkaloid, which corresponds to the longer duration and greater number of alkaloid-dusted fruit flies that were consumed. These findings provide the first experimental evidence that bufonid poison frogs sequester alkaloid-based defenses from dietary sources.

The Population Decline and Extinction of Darwin’s Frogs

PubMed Central

Soto-Azat, Claudio; Valenzuela-Sánchez, Andrés; Collen, Ben; Rowcliffe, J. Marcus; Veloso, Alberto; Cunningham, Andrew A.

2013-01-01

Darwin’s frogs (Rhinoderma darwinii and R. rufum) are two species of mouth-brooding frogs from Chile and Argentina. Here, we present evidence on the extent of declines, current distribution and conservation status of Rhinoderma spp.; including information on abundance, habitat and threats to extant Darwin’s frog populations. All known archived Rhinoderma specimens were examined in museums in North America, Europe and South America. Extensive surveys were carried out throughout the historical ranges of R. rufum and R. darwinii from 2008 to 2012. Literature review and location data of 2,244 archived specimens were used to develop historical distribution maps for Rhinoderma spp. Based on records of sightings, optimal linear estimation was used to estimate whether R. rufum can be considered extinct. No extant R. rufum was found and our modelling inferred that this species became extinct in 1982 (95% CI, 1980–2000). Rhinoderma darwinii was found in 36 sites. All populations were within native forest and abundance was highest in Chiloé Island, when compared with Coast, Andes and South populations. Estimated population size and density (five populations) averaged 33.2 frogs/population (range, 10.2–56.3) and 14.9 frogs/100 m2 (range, 5.3–74.1), respectively. Our results provide further evidence that R. rufum is extinct and indicate that R. darwinii has declined to a much greater degree than previously recognised. Although this species can still be found across a large part of its historical range, remaining populations are small and severely fragmented. Conservation efforts for R. darwinii should be stepped up and the species re-classified as Endangered. PMID:23776705

COMPARATIVE TOXICITY OF DIURON ON SURVIVAL AND GROWTH OF PACIFIC TREEFROG, BULLFROG, RED-LEGGED FROG, AND AFRICAN CLAWED FROG EMBRYOS AND TADPOLES

EPA Science Inventory

The effects of the herbicide diuron on survival and growth of Pacific treefrog (Pseudacris regilla),bullfrog(Rana catesbeiana), red-legged frog(Rana aurora),and African clawed frog(Xenopus laevis)embryos and tadpoles were determined in static-renewal tests. P.regilla and X.laevis...

Effects of the Chytrid fungus on the Tarahumara frog (Rana tarahumarae) in Arizona and Sonora, Mexico

Treesearch

Stephen F. Hale; Philip C. Rosen; James L. Jarchow; Gregory A. Bradley

2005-01-01

We conducted histological analyses on museum specimens collected 1975-1999 from 10 sites in Arizona and Sonora to test for the pathogenic chytrid fungus (Batrachochytrium dendrobatidis) in ranid frogs, focusing on the Tarahumara frog (Rana tarahumarae). During 1981-2000, frogs displaying disease signs were found in the field, and...

49 CFR 213.137 - Frogs.

Code of Federal Regulations, 2011 CFR

2011-10-01

... than 10 m.p.h. (c) If the tread portion of a frog casting is worn down more than three-eighths inch below the original contour, operating speed over that frog shall not be more than 10 m.p.h. (d) Where... 49 Transportation 4 2011-10-01 2011-10-01 false Frogs. 213.137 Section 213.137 Transportation...

Isolation of Brucella inopinata-Like Bacteria from White's and Denny's Tree Frogs.

PubMed

Kimura, Masanobu; Une, Yumi; Suzuki, Michio; Park, Eun-Sil; Imaoka, Koichi; Morikawa, Shigeru

2017-05-01

Brucella inopinata strain BO1 and B. sp. strain BO2 isolated from human patients, respectively, are genetically different from classical Brucella species. We isolated bacteria of the genus Brucella from two species of wild-caught tropical frogs kept in the facilities in Japan: White's tree frog, which inhabits Oceania, and Denny's tree frog, which inhabits Southeast Asia. Phylogenetic analyses based on 16S rRNA and recA gene sequences and multilocus sequence analysis showed that two isolates of Brucella spp. showed significant similarity to BO1, BO2, and the isolates from other wild-caught frogs. These results suggest that a variety of frog species are susceptible to a novel clade of Brucella bacteria, including B. inopinata.

Efficacy of ivermectin as an anthelmintic in leopard frogs.

PubMed

Letcher, J; Glade, M

1992-02-15

Ivermectin administered cutaneously at dosages of 2 mg/kg of body weight eliminated nematode infections in leopard frogs. Three clinical trials were conducted. In the first trial, 5 groups of 11 frogs were given ivermectin IM at dosages of 0, 0.2, 0.4, 2, or 20 mg/kg. All frogs given ivermectin IM at dosages of 2.0 mg/kg or greater died. In trial 2, 44 frogs, allotted to 5 groups, were given ivermectin cutaneously at 0, 0.2, 2, or 20 mg/kg. Cutaneously administered ivermectin was not toxic at dosages up to 20 mg/kg. In trial 3, nematode infections were eliminated in all 10 frogs treated cutaneously with ivermectin at 2.0 mg/kg.

Regulation of 5'-adenosine monophosphate deaminase in the freeze tolerant wood frog, Rana sylvatica.

PubMed

Dieni, Christopher A; Storey, Kenneth B

2008-04-22

The wood frog, Rana sylvatica, is one of a few vertebrate species that have developed natural freeze tolerance, surviving days or weeks with 65-70% of its total body water frozen in extracellular ice masses. Frozen frogs exhibit no vital signs and their organs must endure multiple stresses, particularly long term anoxia and ischemia. Maintenance of cellular energy supply is critical to viability in the frozen state and in skeletal muscle, AMP deaminase (AMPD) plays a key role in stabilizing cellular energetics. The present study investigated AMPD control in wood frog muscle. Wood frog AMPD was subject to multiple regulatory controls: binding to subcellular structures, protein phosphorylation, and effects of allosteric effectors, cryoprotectants and temperature. The percentage of bound AMPD activity increased from 20 to 35% with the transition to the frozen state. Bound AMPD showed altered kinetic parameters compared with the free enzyme (S0.5 AMP was reduced, Hill coefficient fell to approximately 1.0) and the transition to the frozen state led to a 3-fold increase in S0.5 AMP of the bound enzyme. AMPD was a target of protein phosphorylation. Bound AMPD from control frogs proved to be a low phosphate form with a low S0.5 AMP and was phosphorylated in incubations that stimulated PKA, PKC, CaMK, or AMPK. Bound AMPD from frozen frogs was a high phosphate form with a high S0.5 AMP that was reduced under incubation conditions that stimulated protein phosphatases. Frog muscle AMPD was activated by Mg.ATP and Mg.ADP and inhibited by Mg.GTP, KCl, NaCl and NH4Cl. The enzyme product, IMP, uniquely inhibited only the bound (phosphorylated) enzyme from muscle of frozen frogs. Activators and inhibitors differentially affected the free versus bound enzyme. S0.5 AMP of bound AMPD was also differentially affected by high versus low assay temperature (25 vs 5 degrees C) and by the presence/absence of the natural cryoprotectant (250 mM glucose) that accumulates during freezing. Maintenance of long term viability under the ischemic conditions in frozen muscle requires attention to the control of cellular energetics. Differential regulatory controls on AMPD by mechanisms including binding to muscle proteins, actions allosteric effectors, glucose and temperature effects and reversible phosphorylation adjust enzyme function for an optimal role in controlling cellular adenylate levels in ischemic frozen muscle. Stable modification of AMPD properties via freeze-responsive phosphorylation may contribute both to AMPD control and to coordinating AMPD function with other enzymes of energy metabolism in cold ischemic muscle.

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on development of anuran amphibians

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, R.E.; Walker, M.K.

1997-02-01

The authors exposed anuran eggs and tadpoles to vehicle control (0.7% acetone) or waterborne [{sup 3}H]2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for 24 h and subsequently raised them in clean water. Neither American toads nor green frogs exhibited TCDD-related mortality, but leopard frogs showed significantly increased mortality over controls. Eggs and tadpoles eliminated TCDD relatively quickly compared with published data for other vertebrates, with t{sub {1/2}} of 1 to 5 d (American toad), 2 to 7 d (leopard frog), and 4 to 6 d (green frog). Elimination rates were slowest for tadpoles fed nothing, fastest for those fed a low-fat diet, and intermediate formore » those fed a high-fat diet. Although not significant, American toads exposed to {ge}0.03 {micro}g TCDD/L appeared to metamorphose earlier, and those exposed to higher TCDD treatments appeared to metamorphose at a larger body mass than controls. Comparisons of these results with studies of fish early life stages suggest that anuran eggs and tadpoles eliminate TCDD more rapidly and are 100- to 1,000-fold less sensitive to its deleterious effects during development. These differences may be related to differences in metabolic rate, patterns of lipid storage and utilization, and aryl hydrocarbon receptor binding and signal transduction.« less

Prevalence of skeletal and eye malformations in frogs from north-central United States: estimations based on collections from randomly selected sites.

PubMed

Schoff, Patrick K; Johnson, Catherine M; Schotthoefer, Anna M; Murphy, Joseph E; Lieske, Camilla; Cole, Rebecca A; Johnson, Lucinda B; Beasley, Val R

2003-07-01

Skeletal malformation rates for several frog species were determined in a set of randomly selected wetlands in the north-central USA over three consecutive years. In 1998, 62 sites yielded 389 metamorphic frogs, nine (2.3%) of which had skeletal or eye malformations. A subset of the original sites was surveyed in the following 2 yr. In 1999, 1,085 metamorphic frogs were collected from 36 sites and 17 (1.6%) had skeletal or eye malformations, while in 2000, examination of 1,131 metamorphs yielded 16 (1.4%) with skeletal or eye malformations. Hindlimb malformations predominated in all three years, but other abnormalities, involving forelimb, eye, and pelvis were also found. Northern leopard frogs (Rana pipiens) constituted the majority of collected metamorphs as well as most of the malformed specimens. However, malformations were also noted in mink frogs (R. septentrionalis), wood frogs (R. sylvatica), and gray tree frogs (Hyla spp.). The malformed specimens were found in clustered sites in all three years but the cluster locations were not the same in any year. The malformation rates reported here are higher than the 0.3% rate determined for metamorphic frogs collected from similar sites in Minnesota in the 1960s, and thus, appear to represent an elevation of an earlier baseline malformation rate.

Prevalence of skeletal and eye malformations in frogs from north-central United States: estimations based on collections from randomly selected sites

USGS Publications Warehouse

Schoff, P.K.; Johnson, C.M.; Schotthoefer, A.M.; Murphy, J.E.; Lieske, C.; Cole, Rebecca A.; Johnson, L.B.; Beasley, V.R.

2003-01-01

Skeletal malformation rates for several frog species were determined in a set of randomly selected wetlands in the north-central USA over three consecutive years. In 1998, 62 sites yielded 389 metamorphic frogs, nine (2.3%) of which had skeletal or eye malformations. A subset of the original sites was surveyed in the following 2 yr. In 1999, 1,085 metamorphic frogs were collected from 36 sites and 17 (1.6%) had skeletal or eye malformations, while in 2000, examination of 1,131 metamorphs yielded 16 (1.4%) with skeletal or eye malformations. Hindlimb malformations predominated in all three years, but other abnormalities, involving forelimb, eye, and pelvis were also found. Northern leopard frogs (Rana pipiens) constituted the majority of collected metamorphs as well as most of the malformed specimens. However, malformations were also noted in mink frogs (R. septentrionalis), wood frogs (R. sylvatica), and gray tree frogs (Hyla spp.). The malformed specimens were found in clustered sites in all three years but the cluster locations were not the same in any year. The malformation rates reported here are higher than the 0.3% rate determined for metamorphic frogs collected from similar sites in Minnesota in the 1960s, and thus, appear to represent an elevation of an earlier baseline malformation rate.

Partial life-cycle toxicity and bioconcentration modeling of perfluorooctanesulfonate in the northern leopard frog (Rana pipiens).

PubMed

Ankley, Gerald T; Kuehl, Douglas W; Kahl, Michael D; Jensen, Kathleen M; Butterworth, Brian C; Nichols, John W

2004-11-01

A number of recent monitoring studies have demonstrated elevated concentrations of perfluorooctanesulfonate (PFOS) in humans and wildlife throughout the world. Although no longer manufactured in the United States, the global distribution and relative persistence of PFOS indicates a need to understand its potential ecological effects. Presently, little is known concerning toxicity of PFOS in chronic exposures with aquatic species. Therefore, we evaluated the effects of PFOS on survival and development of the northern leopard frog (Rana pipiens) from early embryogenesis through complete metamorphosis. Exposures were conducted via water at measured PFOS concentrations ranging from 0.03 to 10 mg/L. Animals exposed to 10 mg/L began dying within approximately two weeks of test initiation. Survival was not affected by PFOS at lower concentrations; however, time to metamorphosis was delayed and growth reduced in the 3-mg/L treatment group. Tadpoles readily accumulated PFOS directly from water. Using a one-compartment bioaccumulation model, growth was shown to have a modest impact on steady-state PFOS concentrations. Variability in observed growth rates and the possible contribution of a size-dependent decrease in PFOS elimination rate contributed uncertainty to modeling efforts. Nevertheless, fitted uptake and elimination rate constants were comparable to those determined in earlier studies with juvenile rainbow trout. Overall, our studies suggest that R. pipiens is not exceptionally sensitive to PFOS in terms of either direct toxicity or bioconcentration potential of the chemical.

49 CFR 213.143 - Frog guard rails and guard faces; gage.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 4 2013-10-01 2013-10-01 false Frog guard rails and guard faces; gage. 213.143... and guard faces; gage. The guard check and guard face gages in frogs shall be within the limits... frog to the guard line 1 of its guard rail or guarding face, measured across the track at right angles...

49 CFR 213.143 - Frog guard rails and guard faces; gage.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Frog guard rails and guard faces; gage. 213.143... and guard faces; gage. The guard check and guard face gages in frogs shall be within the limits... frog to the guard line 1 of its guard rail or guarding face, measured across the track at right angles...

49 CFR 213.143 - Frog guard rails and guard faces; gage.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Frog guard rails and guard faces; gage. 213.143... and guard faces; gage. The guard check and guard face gages in frogs shall be within the limits... frog to the guard line 1 of its guard rail or guarding face, measured across the track at right angles...

49 CFR 213.143 - Frog guard rails and guard faces; gage.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Frog guard rails and guard faces; gage. 213.143... and guard faces; gage. The guard check and guard face gages in frogs shall be within the limits... frog to the guard line 1 of its guard rail or guarding face, measured across the track at right angles...

49 CFR 213.143 - Frog guard rails and guard faces; gage.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 4 2012-10-01 2012-10-01 false Frog guard rails and guard faces; gage. 213.143... and guard faces; gage. The guard check and guard face gages in frogs shall be within the limits... frog to the guard line 1 of its guard rail or guarding face, measured across the track at right angles...

Terrestrial movements of juvenile and adult tailed frogs in relation to timber harvest in coastal British Columbia

USGS Publications Warehouse

Wahbe, Tanya R.; Bunnell, Fred L.; Bury, R. Bruce

2004-01-01

Tailed frog (Ascaphus truei Stejneger) populations are at risk in much of the Pacific Northwest, and recolonization of sites may be slow postlogging. To examine the terrestrial movements of Ascaphus in clearcuts and old growth, we employed pitfall traps and drift-fence arrays installed along streams and 100 m into upland habitat. In the fall, we captured frogs farther from streams in old growth than in clearcuts, and more frogs were captured a??25 m from streams in clearcuts. Stronger stream affinity in clearcuts was most evident with juvenile frogs, which exhibited more upstream movements than adults. Compared with inland sites where frogs remained close to streams (e.g., 12 m), frogs at our coastal sites were captured at greater distances from streams (a?Y100 m), having lower stream affinity than frogs at inland sites. Long-distance overland movements appear more likely where forested stands are present. Aggregations of Ascaphus at individual streams may not represent distinct populations and should not be managed as distinct units. Preserving groups of interconnected streams within watersheds instead of individual streams will improve the conservation status of Ascaphus. Population monitoring can ensure conservation measures promote long-term persistence.

Effects of Terrestrial Buffer Zones on Amphibians on Golf Courses

PubMed Central

Puglis, Holly J.; Boone, Michelle D.

2012-01-01

A major cause of amphibian declines worldwide is habitat destruction or alteration. Public green spaces, such as golf courses and parks, could serve as safe havens to curb the effects of habitat loss if managed in ways to bolster local amphibian communities. We reared larval Blanchard's cricket frogs (Acris blanchardi) and green frogs (Rana clamitans) in golf course ponds with and without 1 m terrestrial buffer zones, and released marked cricket frog metamorphs at the golf course ponds they were reared in. Larval survival of both species was affected by the presence of a buffer zone, with increased survival for cricket frogs and decreased survival for green frogs when reared in ponds with buffer zones. No marked cricket frog juveniles were recovered at any golf course pond in the following year, suggesting that most animals died or migrated. In a separate study, we released cricket frogs in a terrestrial pen and allowed them to choose between mown and unmown grass. Cricket frogs had a greater probability of using unmown versus mown grass. Our results suggest that incorporating buffer zones around ponds can offer suitable habitat for some amphibian species and can improve the quality of the aquatic environment for some sensitive local amphibians. PMID:22761833

Poison frog colors are honest signals of toxicity, particularly for bird predators.

PubMed

Maan, Martine E; Cummings, Molly E

2012-01-01

Antipredator defenses and warning signals typically evolve in concert. However, the extensive variation across taxa in both these components of predator deterrence and the relationship between them are poorly understood. Here we test whether there is a predictive relationship between visual conspicuousness and toxicity levels across 10 populations of the color-polymorphic strawberry poison frog, Dendrobates pumilio. Using a mouse-based toxicity assay, we find extreme variation in toxicity between frog populations. This variation is significantly positively correlated with frog coloration brightness, a viewer-independent measure of visual conspicuousness (i.e., total reflectance flux). We also examine conspicuousness from the view of three potential predator taxa, as well as conspecific frogs, using taxon-specific visual detection models and three natural background substrates. We find very strong positive relationships between frog toxicity and conspicuousness for bird-specific perceptual models. Weaker but still positive correlations are found for crab and D. pumilio conspecific visual perception, while frog coloration as viewed by snakes is not related to toxicity. These results suggest that poison frog colors can be honest signals of prey unpalatability to predators and that birds in particular may exert selection on aposematic signal design. © 2011 by The University of Chicago.

Do all frogs swim alike? The effect of ecological specialization on swimming kinematics in frogs.

PubMed

Robovska-Havelkova, Pavla; Aerts, Peter; Rocek, Zbynek; Prikryl, Tomas; Fabre, Anne-Claire; Herrel, Anthony

2014-10-15

Frog locomotion has attracted wide scientific interest because of the unusual and derived morphology of the frog pelvic girdle and hind limb. Previous authors have suggested that the design of the frog locomotor system evolved towards a specialized jumping morphology early in the radiation of the group. However, data on locomotion in frogs are biased towards a few groups and most of the ecological and functional diversity remains unexplored. Here, we examine the kinematics of swimming in eight species of frog with different ecologies. We use cineradiography to quantify movements of skeletal elements from the entire appendicular skeleton. Our results show that species with different ecologies do differ in the kinematics of swimming, with the speed of limb extension and especially the kinematics of the midfoot being different. Our results moreover suggest that this is not a phylogenetic effect because species from different clades with similar ecologies converge on the same swimming kinematics. We conclude that it is important to analyze frog locomotion in a broader ecological and evolutionary context if one is to understand the evolutionary origins of this behavior. © 2014. Published by The Company of Biologists Ltd.

Temperature and evaporative water loss of leaf-sitting frogs: the role of reflection spectra

PubMed Central

Blount, Chris; Dickinson, Mark

2016-01-01

ABSTRACT The near infrared reflection peak in some frogs has been speculated to be either for enhancing crypticity, or to help them with thermoregulation. The theoretical background for the thermoregulatory processes has been established before, but little consideration has been given to the contribution from the frogs' reflection spectra differences. In this investigation, the reflection spectra from a range of different species of frogs were taken and combined with precise surface area measurements of frogs and an approximation to the mass transfer coefficient of agar frog models. These were then used to simulate the temperature and water evaporation in anurans with and without the near infrared reflective peak. We have shown that the presence of the near infrared reflection peak can contribute significantly to the temperature and evaporative water loss of a frog. The significance of the steady-state temperature differences between frogs with and without the near infrared reflection peak is discussed in a realistic and an extreme scenario. Temperature differences of up to 3.2°C were found, and the rehydration period was increased by up to 16.7%, although this does not reduce the number of rehydration events between dawn and dusk. PMID:27793832

Molecular anatomy of the developing limb in the coquí frog, Eleutherodactylus coqui.

PubMed

Gross, Joshua B; Kerney, Ryan; Hanken, James; Tabin, Clifford J

2011-01-01

The vertebrate limb demonstrates remarkable similarity in basic organization across phylogenetically disparate groups. To gain further insight into how this morphological similarity is maintained in different developmental contexts, we explored the molecular anatomy of size-reduced embryos of the Puerto Rican coquí frog, Eleutherodactylus coqui. This animal demonstrates direct development, a life-history strategy marked by rapid progression from egg to adult and absence of a free-living, aquatic larva. Nonetheless, coquí exhibits a basal anuran limb structure, with four toes on the forelimb and five toes on the hind limb. We investigated the extent to which coquí limb bud development conforms to the model of limb development derived from amniote studies. Toward this end, we characterized dynamic patterns of expression for 13 critical patterning genes across three principle stages of limb development. As expected, most genes demonstrate expression patterns that are essentially unchanged compared to amniote species. For example, we identified an EcFgf8-expression domain within the apical ectodermal ridge (AER). This expression pattern defines a putatively functional AER signaling domain, despite the absence of a morphological ridge in coquí embryos. However, two genes, EcMeis2 and EcAlx4, demonstrate altered domains of expression, which imply a potential shift in gene function between coquí frogs and amniote model systems. Unexpectedly, several genes thought to be critical for limb patterning in other systems, including EcFgf4, EcWnt3a, EcWnt7a, and EcGremlin, demonstrated no evident expression pattern in the limb at the three stages we analyzed. The absence of EcFgf4 and EcWnt3a expression during limb patterning is perhaps not surprising, given that neither gene is critical for proper limb development in the mouse, based on knockout and expression analyses. In contrast, absence of EcWnt7a and EcGremlin is surprising, given that expression of these molecules appears to be absolutely essential in all other model systems so far examined. Although this analysis substantiates the existence of a core set of ancient limb-patterning molecules, which likely mediate identical functions across highly diverse vertebrate forms, it also reveals remarkable evolutionary flexibility in the genetic control of a conserved morphological pattern across evolutionary time. © 2011 Wiley Periodicals, Inc.

Muscle fatigue in frog semitendinosus: role of intracellular pH

NASA Technical Reports Server (NTRS)

Thompson, L. V.; Balog, E. M.; Fitts, R. H.

1992-01-01

The purpose of this study was to utilize glass microelectrodes to characterize the intracellular pH (pHi) before and during recovery from fatigue in the frog semitendinosus (ST) muscle. A second objective was to evaluate the relationship between pHi and contractile function. The frog ST muscle (22 degrees C) was fatigued by direct electrical stimulation with 100-ms 150-Hz trains at 1/s for 5 min. Peak tetanic force (Po) was reduced to 8.5% of initial force and recovered in a biphasic manner, returning to the resting value by 40 min. Resting pHi was 7.00 +/- 0.02 (n = 37) and declined with fatigue to an average value of 6.42 at 3 min of recovery. During recovery pHi significantly increased and by 25 min had returned to the prefatigue value. The pHi recovery was highly correlated to the slow phase of Po recovery (r = 0.98, P less than 0.001). The mean resting membrane potential was -78 +/- 1.0 mV (n = 42) and at 3 min of recovery was depolarized to -67 +/- 4 mV. Both the peak rate of twitch force development (+dP/dt) (r = 0.99, P less than 0.001) and decline (-dP/dt) (r = 0.94, P less than 0.014) were highly correlated to pHi during the slow phase of recovery. Contraction time (CT) and one-half relaxation time (1/2RT) increased significantly and recovered exponentially. The recovery of CT and 1/2RT were both significantly correlated to pHi (r = -0.93, P less than 0.001 and r = -0.86, P less than 0.001 for CT and 1/2RT, respectively).(ABSTRACT TRUNCATED AT 250 WORDS).

Impact of maternal n-3 polyunsaturated fatty acid deficiency on dendritic arbor morphology and connectivity of developing Xenopus laevis central neurons in vivo.

PubMed

Igarashi, Miki; Santos, Rommel A; Cohen-Cory, Susana

2015-04-15

Docosahexaenoic acid (DHA, 22:6n-3) is an essential component of the nervous system, and maternal n-3 polyunsaturated fatty acids (PUFAs) are an important source for brain development. Here, the impact of DHA on developing central neurons was examined using an accessible in vivo model. Xenopus laevis embryos from adult female frogs fed n-3 PUFA-adequate or deficient diets were analyzed every 10 weeks for up to 60 weeks, when frogs were then switched to a fish oil-supplemented diet. Lipid analysis showed that DHA was significantly reduced both in oocytes and tadpoles 40 weeks after deprivation, and brain DHA was reduced by 57% at 60 weeks. In vivo imaging of single optic tectal neurons coexpressing tdTomato and PSD-95-GFP revealed that neurons were morphologically simpler in tadpoles from frogs fed the deficient diet compared with the adequate diet. Tectal neurons had significantly fewer dendrite branches and shorter dendritic arbor over a 48 h imaging period. Postsynaptic cluster number and density were lower in neurons deprived of n-3 PUFA. Moreover, changes in neuronal morphology correlated with a 40% decrease in the levels of BDNF mRNA and mature protein in the brain, but not in TrkB. Importantly, switching to a fish oil-supplemented diet induced a recovery in DHA content in the frog embryos within 20 weeks and diminished the deprivation effects observed on tectal neurons of Stage 45 tadpoles. Consequently, our results indicate that DHA impacts dendrite maturation and synaptic connectivity in the developing brain, and it may be involved in neurotrophic support by BDNF. Copyright © 2015 the authors 0270-6474/15/356079-14$15.00/0.

"RED-LEG"—AN INFECTIOUS DISEASE OF FROGS

PubMed Central

Emerson, Haven; Norris, Charles

1905-01-01

The epidemics we have observed, were due to the presence and growth in the frogs of Bacillus hydrophilus fuscus. This was proved by recovering the bacillus in pure culture from the body fluids of frogs sick or dead of the disease, and the inoculation of healthy frogs with an emulsion of the pure culture, and by obtaining the same clinical picture and pathological findings as in the original diseased frogs; and, finally, by recovering the bacillus in pure culture from frogs inoculated and sick or dying as a result of the inoculation. The disease is widely distributed throughout North America and Europe, and in this country and Canada is known as "red-leg." It has been observed by us chiefly in the warm weather of September and October. The disease is characterized by congestion of the ventral surfaces of the body, with more or less ulceration in, and hæmorrhage beneath, the skin, bloating due to serous exudation into the lymph sacs, gradual failure to respond to stimuli, which symptoms are followed by coma and death, the last being occasionally preceded by tetanic seizures. After death hæmorrhages into the muscles and degenerative changes in the muscles, spleen, liver, and, to a slight degree, in the intestinal tract, are found. The blood shows an advanced degree of anæmia and leucocytosis. Predisposing causes of the disease are lesions of the skin, which seem to be the usual portal of entry of the infection, and lowered resistance from heat and from anæmia. By a series of controlled experiments with inoculated frogs we have shown that, while temperatures a little above freezing have no harmful effect upon the frogs, they completely control all manifestations of the disease in inoculated or diseased frogs, if the frogs are left in the cold for a period as long as seven days; and, further, that even short periods in the cold chamber will bring about a delay of the fatal results in diseased or inoculated frogs. The anæmia so often found in apparently healthy frogs seems in many cases to be due to the presence in the lungs of the frog of a parasite, the Distomum cylindraceum, which, occurring in sufficiently large numbers in an individual frog, is capable of materially diminishing the available supply of red corpuscles. Severe laking of the blood, the presence of numerous isolated red-cell nuclei, and great diminution in the number, or almost total absence of the red cells in the diseased frogs, are in proportion to the severity of the infection and due to bacterial action. The presence of the hæmatozoan parasite, the Drepanidium, does not play any part as a predisposing or exciting cause of the disease. The ascarid Rhabdomena nigrovenosum, although frequently present as a parasite in the lungs of the frogs, plays no part in causing or promoting the disease. PMID:19866986

Sound source localization and segregation with internally coupled ears: the treefrog model

PubMed Central

Christensen-Dalsgaard, Jakob

2016-01-01

Acoustic signaling plays key roles in mediating many of the reproductive and social behaviors of anurans (frogs and toads). Moreover, acoustic signaling often occurs at night, in structurally complex habitats, such as densely vegetated ponds, and in dense breeding choruses characterized by high levels of background noise and acoustic clutter. Fundamental to anuran behavior is the ability of the auditory system to determine accurately the location from where sounds originate in space (sound source localization) and to assign specific sounds in the complex acoustic milieu of a chorus to their correct sources (sound source segregation). Here, we review anatomical, biophysical, neurophysiological, and behavioral studies aimed at identifying how the internally coupled ears of frogs contribute to sound source localization and segregation. Our review focuses on treefrogs in the genus Hyla, as they are the most thoroughly studied frogs in terms of sound source localization and segregation. They also represent promising model systems for future work aimed at understanding better how internally coupled ears contribute to sound source localization and segregation. We conclude our review by enumerating directions for future research on these animals that will require the collaborative efforts of biologists, physicists, and roboticists. PMID:27730384

[Biomechanical characteristics of the wiping reflex cycle].

PubMed

Berkinblit, M B; Zharkova, I S; Fel'dman, A G; Fukson, O I

1984-01-01

Multijoint goal-directed hindlimb movements in response to chemical stimulation delivered to different skin sites on the medial back surface (wiping reflex-WR) were filmed and analysed in spinal or intact frogs Rana temporaria. Each WR cycle was divisible into five phases (flexion, lifting, aiming, wiping and extension) usually separated from each other by postural interruptions. One or several of the phases might spontaneously be reduced or deleted at all (e. g. the extension phase), although the WR was still effective. Such a reduction was, as a rule, observed in intact frogs while spinal ones usually exhibited the maximum phase sequence. It is suggested that the central spinal generator of the WR is formed of separate functional blocks each of which specifies a certain interjoint coordination and brings the joints to the central-conditioned equilibrium positions.

In Vivo Confocal Intrinsic Optical Signal Identification of Localized Retinal Dysfunction

PubMed Central

Zhang, Qiu-Xiang; Lu, Rong-Wen; Curcio, Christine A.; Yao, Xin-Cheng

2012-01-01

Purpose. The purposes of this study were to investigate the physiological mechanism of stimulus-evoked fast intrinsic optical signals (IOSs) recorded in dynamic confocal imaging of the retina, and to demonstrate the feasibility of in vivo confocal IOS mapping of localized retinal dysfunctions. Methods. A rapid line-scan confocal ophthalmoscope was constructed to achieve in vivo confocal IOS imaging of frog (Rana pipiens) retinas at cellular resolution. In order to investigate the physiological mechanism of confocal IOS, comparative IOS and electroretinography (ERG) measurements were made using normal frog eyes activated by variable-intensity stimuli. A dynamic spatiotemporal filtering algorithm was developed to reject the contamination of hemodynamic changes on fast IOS recording. Laser-injured frog eyes were employed to test the potential of confocal IOS mapping of localized retinal dysfunctions. Results. Comparative IOS and ERG experiments revealed a close correlation between the confocal IOS and retinal ERG, particularly the ERG a-wave, which has been widely used to evaluate photoreceptor function. IOS imaging of laser-injured frog eyes indicated that the confocal IOS could unambiguously detect localized (30 μm) functional lesions in the retina before a morphological abnormality is detectable. Conclusions. The confocal IOS predominantly results from retinal photoreceptors, and can be used to map localized photoreceptor lesion in laser-injured frog eyes. We anticipate that confocal IOS imaging can provide applications in early detection of age-related macular degeneration, retinitis pigmentosa, and other retinal diseases that can cause pathological changes in the photoreceptors. PMID:23150616

The Classroom Animal: The Leopard Frog.

ERIC Educational Resources Information Center

Science and Children, 1985

1985-01-01

Describes the natural history of the leopard frog and factors which make it appropriate for short-term study in the classroom. Information on the frog's habits, life cycle, housing, care, and health is included. (DH)

Parasites of the mink frog (rana septentrionalis) from Minnesota, U.S.A.

USGS Publications Warehouse

Schotthoefer, Anna M.; Bolek, M.G.; Cole, Rebecca A.; Beasley, Val R.

2009-01-01

Twenty-two mink frogs, Rana septentrionalis, collected from two locations in Minnesota, United States, were examined for helminth and protozoan blood parasites in July 1999. A total of 16 parasite taxa were recovered including 5 larval digenean trematodes, 7 adult digenean trematodes, 3 nematodes, and I Trypanosorna species. Infracommunities were dominated by the digeneans in terms of richness and abundance. In particular, echinostomatid metacercariae in the kidneys of frogs were the most common parasites found, infecting 100% of the frogs and consisting of about 90% of all helminth individuals recovered. Gorgodera amplicava, Gorgoderina multilohata, Haernaroloechus pan'iplexus, Haernatoloechus breviplexus, Cosnwcercoides dukae, and Oswaldocruzia pipiens represent new host records. The survey presented here represents the second known helminth survey of mink frogs conducted in North America. A summary of metazoan parasites reported from mink frogs is included.

Ovarian dysgerminomas in two mountain chicken frogs (Leptodactylus fallax).

PubMed

Fitzgerald, Scott D; Duncan, Ann E; Tabaka, Chris; Garner, Michael M; Dieter, April; Kiupel, Matti

2007-03-01

This report describes the gross, histologic, and immunohistochemical features of ovarian dysgerminomas in two adult female mountain chicken frogs (Leptodactylusfallax) from the same zoological institution. One frog was found dead, and the other frog had been ill for several days with a bloated abdomen and lethargy. On necropsy, large, pale multilobulated masses replaced the left ovary in both frogs, and one frog also had numerous smaller nodules scattered throughout the coelomic viscera. Histologically, these masses were composed of sheets and cords of polyhedral discrete germ cells consistent with the diagnosis of dysgerminoma. Neoplastic cells stained positive with immunohistochemistry for Oct4, which has been reported to detect stem cells including germ cells in a variety of species, including humans. Ovarian tumors are uncommonly encountered in both reptiles and amphibians, and this report is the first report of dysgerminoma in any amphibian species.

Trypanosome transmission by Corethrella wirthi (Diptera: Chaoboridae) to the green treefrog, Hyla cinerea (Anura: Hylidae).

PubMed

Johnson, R N; Young, D G; Butler, J F

1993-09-01

Seventy-two percent of 215 male green tree frog, Hyla cinerea (Schneider), captured in Alachua and Levy counties, FL, between April and mid-September 1978 and 1979 were infected with an undescribed Trypanosoma sp. None of the 31 female frogs captured concurrently was infected. Periodic sampling of the peripheral blood from the infected male frogs showed that the trypanosomes were present in high numbers only at night. Conspecific trypanosomes also were found in the mid and hind guts of female Corethrella wirthi Stone flies collected on or near male frogs in the field. Transmission of the parasite to uninfected frogs was demonstrated by exposure of male and female frogs to naturally infected flies and to parasites injected subdermally. This is the first report of parasite transmission by a species of Corethrella.

Sexual differences in prevalence of a new species of trypanosome infecting túngara frogs

PubMed Central

Bernal, Ximena E.; Pinto, C. Miguel

2016-01-01

Trypanosomes are a diverse group of protozoan parasites of vertebrates transmitted by a variety of hematophagous invertebrate vectors. Anuran trypanosomes and their vectors have received relatively little attention even though these parasites have been reported from frog and toad species worldwide. Blood samples collected from túngara frogs (Engystomops pustulosus), a Neotropical anuran species heavily preyed upon by eavesdropping frog-biting midges (Corethrella spp.), were examined for trypanosomes. Our results revealed sexual differences in trypanosome prevalence with female frogs being rarely infected (<1%). This finding suggests this protozoan parasite may be transmitted by frog-biting midges that find their host using the mating calls produced by male frogs. Following previous anuran trypanosome studies, we examined 18S ribosomal RNA gene to characterize and establish the phylogenetic relationship of the trypanosome species found in túngara frogs. A new species of giant trypanosome, Trypanosoma tungarae n. sp., is described in this study. Overall the morphometric data revealed that the trypomastigotes of T. tungarae n. sp. are similar to other giant trypanosomes such as Trypanosoma rotatorium and Trypanosoma ranarum. Despite its slender and long cell shape, however, 18S rRNA gene sequences revealed that T. tungarae n. sp. is sister to the rounded-bodied giant trypanosome, Trypanosoma chattoni. Therefore, morphological convergence explains similar morphology among members of two non-closely related groups of trypanosomes infecting frogs. The results from this study underscore the value of coupling morphological identification with molecular characterization of anuran trypanosomes. PMID:26977404

Sexual differences in prevalence of a new species of trypanosome infecting túngara frogs.

PubMed

Bernal, Ximena E; Pinto, C Miguel

2016-04-01

Trypanosomes are a diverse group of protozoan parasites of vertebrates transmitted by a variety of hematophagous invertebrate vectors. Anuran trypanosomes and their vectors have received relatively little attention even though these parasites have been reported from frog and toad species worldwide. Blood samples collected from túngara frogs (Engystomops pustulosus), a Neotropical anuran species heavily preyed upon by eavesdropping frog-biting midges (Corethrella spp.), were examined for trypanosomes. Our results revealed sexual differences in trypanosome prevalence with female frogs being rarely infected (<1%). This finding suggests this protozoan parasite may be transmitted by frog-biting midges that find their host using the mating calls produced by male frogs. Following previous anuran trypanosome studies, we examined 18S ribosomal RNA gene to characterize and establish the phylogenetic relationship of the trypanosome species found in túngara frogs. A new species of giant trypanosome, Trypanosoma tungarae n. sp., is described in this study. Overall the morphometric data revealed that the trypomastigotes of T. tungarae n. sp. are similar to other giant trypanosomes such as Trypanosoma rotatorium and Trypanosoma ranarum. Despite its slender and long cell shape, however, 18S rRNA gene sequences revealed that T. tungarae n. sp. is sister to the rounded-bodied giant trypanosome, Trypanosoma chattoni. Therefore, morphological convergence explains similar morphology among members of two non-closely related groups of trypanosomes infecting frogs. The results from this study underscore the value of coupling morphological identification with molecular characterization of anuran trypanosomes.

Do cryptic species exist in Hoplobatrachus rugulosus? An examination using four nuclear genes, the cyt b gene and the complete MT genome.

PubMed

Yu, Danna; Zhang, Jiayong; Li, Peng; Zheng, Rongquan; Shao, Chen

2015-01-01

he Chinese tiger frog Hoplobatrachus rugulosus is widely distributed in southern China, Malaysia, Myanmar, Thailand, and Vietnam. It is listed in Appendix II of CITES as the only Class II nationally-protected frog in China. The bred tiger frog known as the Thailand tiger frog, is also identified as H. rugulosus. Our analysis of the Cyt b gene showed high genetic divergence (13.8%) between wild and bred samples of tiger frog. Unexpected genetic divergence of the complete mt genome (14.0%) was also observed between wild and bred samples of tiger frog. Yet, the nuclear genes (NCX1, Rag1, Rhod, Tyr) showed little divergence between them. Despite this and their very similar morphology, the features of the mitochondrial genome including genetic divergence of other genes, different three-dimensional structures of ND5 proteins, and gene rearrangements indicate that H. rugulosus may be a cryptic species complex. Using Bayesian inference, maximum likelihood, and maximum parsimony analyses, Hoplobatrachus was resolved as a sister clade to Euphlyctis, and H. rugulosus (BT) as a sister clade to H. rugulosus (WT). We suggest that we should prevent Thailand tiger frogs (bred type) from escaping into wild environments lest they produce hybrids with Chinese tiger frogs (wild type).

Do Cryptic Species Exist in Hoplobatrachus rugulosus? An Examination Using Four Nuclear Genes, the Cyt b Gene and the Complete MT Genome

PubMed Central

Li, Peng; Zheng, Rongquan; Shao, Chen

2015-01-01

he Chinese tiger frog Hoplobatrachus rugulosus is widely distributed in southern China, Malaysia, Myanmar, Thailand, and Vietnam. It is listed in Appendix II of CITES as the only Class II nationally-protected frog in China. The bred tiger frog known as the Thailand tiger frog, is also identified as H. rugulosus. Our analysis of the Cyt b gene showed high genetic divergence (13.8%) between wild and bred samples of tiger frog. Unexpected genetic divergence of the complete mt genome (14.0%) was also observed between wild and bred samples of tiger frog. Yet, the nuclear genes (NCX1, Rag1, Rhod, Tyr) showed little divergence between them. Despite this and their very similar morphology, the features of the mitochondrial genome including genetic divergence of other genes, different three-dimensional structures of ND5 proteins, and gene rearrangements indicate that H. rugulosus may be a cryptic species complex. Using Bayesian inference, maximum likelihood, and maximum parsimony analyses, Hoplobatrachus was resolved as a sister clade to Euphlyctis, and H. rugulosus (BT) as a sister clade to H. rugulosus (WT). We suggest that we should prevent Thailand tiger frogs (bred type) from escaping into wild environments lest they produce hybrids with Chinese tiger frogs (wild type). PMID:25875761

Metamorphosis increases biotransformation of polychlorinated biphenyls: a comparative study of polychlorinated biphenyl metabolism in green frogs (Rana clamitans) and leopard frogs (Rana pipiens) at various life stages.

PubMed

Leney, Jocelyn L; Drouillard, Ken G; Haffner, G Douglas

2006-11-01

Polychlorinated biphenyl (PCB) elimination rates were used to determine whether green frogs (Rana clamitans) and leopard frogs (Rana pipiens) at three life stages (tadpole, metamorph, and adult) were capable of metabolic biotransformation of PCBs. Polychlorinated biphenyls were grouped according to their structural properties to determine whether congeners with specific structures were eliminated more rapidly than others, which would suggest the occurrence of metabolic biotransformation. For both species and at all life stages studied, PCBs with adjacent unsubstituted meta-para sites (group-2 PCBs) were eliminated significantly faster than PCBs with adjacent unsubstituted ortho-meta sites (group-3 PCBs). Because these groups of PCBs span similar hydrophobicity ranges, it was concluded that green and leopard frogs can selectively metabolize group-2 PCBs. Metabolic activity was more pronounced in the metamorph stage than in any other life stage. In green frog metamorphs, the average elimination rate of the group-2 PCBs was 4.9-fold greater than that of the group-3 PCBs. By contrast, in green frog tadpoles, group-2 PCBs were eliminated 1.9-fold faster than group-3 PCBs, and in green frog adults, group-2 PCBs were eliminated 1.5-fold faster than group-3 PDBs.

Abundance of Green Tree Frogs and Insects in Artificial Canopy Gaps in a Bottomland Hardwood Forest.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horn, Scott; Hanula, James, L.; Ulyshen, Michael D.

2005-04-01

ABSTRACT - We found more green tree frogs ( Hyla cinerea) n canopv gaps than in closed canopy forest. Of the 331 green tree frogs observed, 88% were in canopv gaps. Likewise, higher numbers and biomasses of insects were captured in the open gap habitat Flies were the most commonlv collected insect group accounting for 54% of the total capture. These data suggest that one reason green tree frogs were more abundant in canopy gaps was the increased availability of prey and that small canopy gaps provide early successional habitats that are beneficial to green tree frog populations.

Regulation of Ca2+ Sparks by Ca2+ and Mg2+ in Mammalian and Amphibian Muscle. An RyR Isoform-specific Role in Excitation–Contraction Coupling?

PubMed Central

Zhou, Jingsong; Launikonis, Bradley S.; Ríos, Eduardo; Brum, Gustavo

2004-01-01

Ca2+ and Mg2+ are important mediators and regulators of intracellular Ca2+ signaling in muscle. The effects of changes of cytosolic [Ca2+] or [Mg2+] on elementary Ca2+ release events were determined, as functions of concentration and time, in single fast-twitch permeabilized fibers of rat and frog. Ca2+ sparks were identified and their parameters measured in confocal images of fluo-4 fluorescence. Solutions with different [Ca2+] or [Mg2+] were rapidly exchanged while imaging. Faster and spatially homogeneous changes of [Ca2+] (reaching peaks >100 μM) were achieved by photolysing Ca NP-EGTA with laser flashes. In both species, incrementing cytosolic [Ca2+] caused a steady, nearly proportional increase in spark frequency, reversible upon [Ca2+] reduction. A greater change in spark frequency, usually transient, followed sudden increases in [Ca2+] after a lag of 100 ms or more. The nonlinearity, lag, and other features of this delayed effect suggest that it requires increase of [Ca2+] inside the SR. In the frog only, increases in cytosolic [Ca2+] often resulted, after a lag, in sparks that propagated transversally. An increase in [Mg2+] caused a fall of spark frequency, but with striking species differences. In the rat, but not the frog, sparks were observed at 4–40 mM [Mg2+]. Reducing [Mg2+] below 2 mM, which should enable the RyR channel's activation (CICR) site to bind Ca2+, caused progressive increase in spark frequency in the frog, but had no effect in the rat. Spark propagation and enhancement by sub-mM Mg2+ are hallmarks of CICR. Their absence in the rat suggests that CICR requires RyR3 para-junctional clusters, present only in the frog. The observed frequency of sparks corresponds to a channel open probability of 10−7 in the frog or 10−8 in the rat. Together with the failure of photorelease to induce activation directly, this indicates a basal inhibition of channels in situ. It is proposed that relief of this inhibition could be the mechanism by which increased SR load increases spark frequency. PMID:15452201

Host-Defense Peptides with Therapeutic Potential from Skin Secretions of Frogs from the Family Pipidae

PubMed Central

Conlon, J. Michael; Mechkarska, Milena

2014-01-01

Skin secretions from frogs belonging to the genera Xenopus, Silurana, Hymenochirus, and Pseudhymenochirus in the family Pipidae are a rich source of host-defense peptides with varying degrees of antimicrobial activities and cytotoxicities to mammalian cells. Magainin, peptide glycine-leucine-amide (PGLa), caerulein-precursor fragment (CPF), and xenopsin-precursor fragment (XPF) peptides have been isolated from norepinephrine-stimulated skin secretions from several species of Xenopus and Silurana. Hymenochirins and pseudhymenochirins have been isolated from Hymenochirus boettgeri and Pseudhymenochirus merlini. A major obstacle to the development of these peptides as anti-infective agents is their hemolytic activities against human erythrocytes. Analogs of the magainins, CPF peptides and hymenochirin-1B with increased antimicrobial potencies and low cytotoxicities have been developed that are active (MIC < 5 μM) against multidrug-resistant clinical isolates of Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, Stenotrophomonas maltophilia and Klebsiella pneumoniae. Despite this, the therapeutic potential of frog skin peptides as anti-infective agents has not been realized so that alternative clinical applications as anti-cancer, anti-viral, anti-diabetic, or immunomodulatory drugs are being explored. PMID:24434793

An improved shuffled frog leaping algorithm based evolutionary framework for currency exchange rate prediction

NASA Astrophysics Data System (ADS)

Dash, Rajashree

2017-11-01

Forecasting purchasing power of one currency with respect to another currency is always an interesting topic in the field of financial time series prediction. Despite the existence of several traditional and computational models for currency exchange rate forecasting, there is always a need for developing simpler and more efficient model, which will produce better prediction capability. In this paper, an evolutionary framework is proposed by using an improved shuffled frog leaping (ISFL) algorithm with a computationally efficient functional link artificial neural network (CEFLANN) for prediction of currency exchange rate. The model is validated by observing the monthly prediction measures obtained for three currency exchange data sets such as USD/CAD, USD/CHF, and USD/JPY accumulated within same period of time. The model performance is also compared with two other evolutionary learning techniques such as Shuffled frog leaping algorithm and Particle Swarm optimization algorithm. Practical analysis of results suggest that, the proposed model developed using the ISFL algorithm with CEFLANN network is a promising predictor model for currency exchange rate prediction compared to other models included in the study.

Frog skin cultures secrete anti-yellow fever compounds.

PubMed

Muñoz-Camargo, Carolina; Méndez, Margarita Correa; Salazar, Vivian; Moscoso, Johanna; Narváez, Diana; Torres, Maria Mercedes; Florez, Franz Kaston; Groot, Helena; Mitrani, Eduardo

2016-11-01

There is an urgent need to develop novel antimicrobial substances. Antimicrobial peptides (AMPs) are considered as promising candidates for future therapeutic use. Because of the re-emergence of the Flavivirus infection, and particularly the yellow fever virus (YFV), we have compared the antiviral activities from skin secretions of seven different frog species against YFV (strain 17D). Secretions from Sphaenorhynchus lacteus, Cryptobatrachus boulongeri and Leptodactylus fuscus displayed the more powerful activities. S. lacteus was found to inhibit viral lysis of Vero E6 cells even at the highest viral concentration evaluated of 10 LD 50 . We also report the identification of a novel frenatin-related peptide from S. lacteus and found that this peptide-on its own-can lead to 35% protection against YVF, while displaying no cytotoxicity against somatic cells even at fivefold higher concentrations. These results are attractive and support the need for continued exploration of new sources of AMPs from frog skin secretions such as those described here in the development of new compounds for the treatment of infectious diseases in general and specific viral infections in particular.

Persistent lung oscillator response to CO2 after buccal oscillator inhibition in the adult frog.

PubMed

Leclère, Renaud; Straus, Christian; Similowski, Thomas; Bodineau, Laurence; Fiamma, Marie-Noëlle

2012-08-15

The automatic ventilatory drive in amphibians depends on two oscillators interacting with each other, the gill/buccal and lung oscillators. The lung oscillator would be homologous to the mammalian pre-Bötzinger complex and the gill/buccal oscillator homologous to the mammalian parafacial respiratory group/retrotrapezoid nucleus (pFRG/RTN). Dysfunction of the pFRG/RTN has been involved in the development of respiratory diseases associated to the loss of CO(2) chemosensitivity such as the congenital central hypoventilation syndrome. Here, on adult in vitro isolated frog brainstem, consequences of the buccal oscillator inhibition (by reducing Cl(-)) were evaluated on the respiratory rhythm developed by the lung oscillator under hypercapnic challenges. Our results show that under low Cl(-) concentration (i) the buccal oscillator is strongly inhibited and the lung burst frequency and amplitude decreased and (ii) it persists a powerful CO(2) chemosensitivity. In conclusion, in frog, the CO(2) chemosensitivity depends on cellular contingent(s) whose the functioning is independent of the concentration of Cl(-) and origin remains unknown. Copyright © 2012 Elsevier B.V. All rights reserved.

Combined Effects of Pesticides and Trematode Infections on Hourglass Tree Frog Polypedates cruciger

PubMed Central

Jayawardena, Uthpala A.; Rohr, Jason R.; Navaratne, Ayanthi N.; Amerasinghe, Priyanie H.; Rajakaruna, Rupika S.

2016-01-01

The impact of widespread and common environmental factors, such as chemical contaminants, on infectious disease risk in amphibians is particularly important because both chemical contaminants and infectious disease have been implicated in worldwide amphibian declines. Here we report on the lone and combined effects of exposure to parasitic cercariae (larval stage) of the digenetic trematode, Acanthostomum burminis, and four commonly used pesticides (insecticides: chlorpyrifos, dimethoate; herbicides: glyphosate, propanil) at ecologically relevant concentrations on the survival, growth, and development of the common hourglass tree frog, Polypedates cruciger Blyth 1852. There was no evidence of any pesticide-induced mortality on cercariae because all the cercariae successfully penetrated each tadpole host regardless of pesticide treatment. In isolation, both cercarial and pesticide exposure significantly decreased frog survival, development, and growth, and increased developmental malformations, such as scoliosis, kyphosis, and also edema and skin ulcers. The combination of cercariae and pesticides generally posed greater risk to frogs than either factor alone by decreasing survival or growth or increasing time to metamorphosis or malformations. The exception was that lone exposure to chlorpyrifos had higher mortality without than with cercariae. Consistent with mathematical models that suggest that stress should increase the impact of generalist parasites, the weight of the evidence from the field and laboratory suggests that ecologically relevant concentrations of agrochemicals generally increase the threat that trematodes pose to amphibians, highlighting the importance of elucidating interactions between anthropogenic activities and infectious disease in taxa of conservation concern. PMID:26911919

Combined Effects of Pesticides and Trematode Infections on Hourglass Tree Frog Polypedates cruciger.

PubMed

Jayawardena, Uthpala A; Rohr, Jason R; Navaratne, Ayanthi N; Amerasinghe, Priyanie H; Rajakaruna, Rupika S

2016-03-01

The impact of widespread and common environmental factors, such as chemical contaminants, on infectious disease risk in amphibians is particularly important because both chemical contaminants and infectious disease have been implicated in worldwide amphibian declines. Here we report on the lone and combined effects of exposure to parasitic cercariae (larval stage) of the digenetic trematode, Acanthostomum burminis, and four commonly used pesticides (insecticides: chlorpyrifos, dimethoate; herbicides: glyphosate, propanil) at ecologically relevant concentrations on the survival, growth, and development of the common hourglass tree frog, Polypedates cruciger Blyth 1852. There was no evidence of any pesticide-induced mortality on cercariae because all the cercariae successfully penetrated each tadpole host regardless of pesticide treatment. In isolation, both cercarial and pesticide exposure significantly decreased frog survival, development, and growth, and increased developmental malformations, such as scoliosis, kyphosis, and also edema and skin ulcers. The combination of cercariae and pesticides generally posed greater risk to frogs than either factor alone by decreasing survival or growth or increasing time to metamorphosis or malformations. The exception was that lone exposure to chlorpyrifos had higher mortality without than with cercariae. Consistent with mathematical models that suggest that stress should increase the impact of generalist parasites, the weight of the evidence from the field and laboratory suggests that ecologically relevant concentrations of agrochemicals generally increase the threat that trematodes pose to amphibians, highlighting the importance of elucidating interactions between anthropogenic activities and infectious disease in taxa of conservation concern.

Mosquito repellents in frog skin

PubMed Central

Williams, C.R; Smith, B.P.C; Best, S.M; Tyler, M.J

2006-01-01

The search for novel insect repellents has been driven by health concerns over established synthetic compounds such as diethyl-m-toluamide (DEET). Given the diversity of compounds known from frog skin and records of mosquito bite and ectoparasite infestation, the presence of mosquito repellents in frogs seemed plausible. We investigated frog skin secretions to confirm the existence of mosquito repellent properties. Litoria caerulea secretions were assessed for mosquito repellency by topical application on mice. The secretions provided protection against host-seeking Culex annulirostris mosquitoes. Olfactometer tests using aqueous washes of skin secretions from L. caerulea and four other frog species were conducted to determine whether volatile components were responsible for repellency. Volatiles from Litoria rubella and Uperoleia mjobergi secretions were repellent to C. annulirostris, albeit not as repellent as a DEET control. The demonstration of endogenous insect repellents in amphibians is novel, and demonstrates that many aspects of frog chemical ecology remain unexplored. PMID:17148373

Description of the tadpoles of two endemic frogs: the Phu Luang cascade frog Odorrana aureola (Anura: Ranidae) and the Isan big-headed frog Limnonectes isanensis (Anura: Dicroglossidae) from northeastern Thailand.

PubMed

Ampai, Natee; Rujirawan, Attapol; Arkajag, Jirachai; Mcleod, David S; Aowphol, Anchalee

2015-07-07

We describe the external morphology of the tadpoles of two frogs endemic to Thailand: the Phu Luang cascade frog    (Odorrana aureola) and the Isan big-headed frog (Limnonectes isanensis) from the type localities in the Phu Luang Wildlife Sanctuary, Loei Province, northeastern Thailand. Morphological and genetic characters (16S rRNA) were used to identify specimen and match tadpoles to the adults. Detailed descriptions of external morphology and coloration in life are provided for both species. We provide a brief discussion of the ecology of these tadpoles and a comparison to previously published data from tadpoles of closely related taxa. Additionally, we provide evidence for the utility of larval morphology in resolving the taxonomic puzzles presented by cryptic species complexes.

New effects of Roundup on amphibians: predators reduce herbicide mortality; herbicides induce antipredator morphology.

PubMed

Relyea, Rick A

2012-03-01

The use of pesticides is important for growing crops and protecting human health by reducing the prevalence of targeted pest species. However, less attention is given to the potential unintended effects on nontarget species, including taxonomic groups that are of current conservation concern. One issue raised in recent years is the potential for pesticides to become more lethal in the presence of predatory cues, a phenomenon observed thus far only in the laboratory. A second issue is whether pesticides can induce unintended trait changes in nontarget species, particularly trait changes that might mimic adaptive responses to natural environmental stressors. Using outdoor mesocosms, I created simple wetland communities containing leaf litter, algae, zooplankton, and three species of tadpoles (wood frogs [Rana sylvatica or Lithobates sylvaticus], leopard frogs [R. pipiens or L. pipiens], and American toads [Bufo americanus or Anaxyrus americanus]). I exposed the communities to a factorial combination of environmentally relevant herbicide concentrations (0, 1, 2, or 3 mg acid equivalents [a.e.]/L of Roundup Original MAX) crossed with three predator-cue treatments (no predators, adult newts [Notophthalmus viridescens], or larval dragonflies [Anax junius]). Without predator cues, mortality rates from Roundup were consistent with past studies. Combined with cues from the most risky predator (i.e., dragonflies), Roundup became less lethal (in direct contrast to past laboratory studies). This reduction in mortality was likely caused by the herbicide stratifying in the water column and predator cues scaring the tadpoles down to the benthos where herbicide concentrations were lower. Even more striking was the discovery that Roundup induced morphological changes in the tadpoles. In wood frog and leopard frog tadpoles, Roundup induced relatively deeper tails in the same direction and of the same magnitude as the adaptive changes induced by dragonfly cues. To my knowledge, this is the first study to show that a pesticide can induce morphological changes in a vertebrate. Moreover, the data suggest that the herbicide might be activating the tadpoles' developmental pathways used for antipredator responses. Collectively, these discoveries suggest that the world's most widely applied herbicide may have much further-reaching effects on nontarget species than previous considered.

Critical Points and Traveling Wave in Locomotion: Experimental Evidence and Some Theoretical Considerations.

PubMed

Saltiel, Philippe; d'Avella, Andrea; Tresch, Matthew C; Wyler, Kuno; Bizzi, Emilio

2017-01-01

The central pattern generator (CPG) architecture for rhythm generation remains partly elusive. We compare cat and frog locomotion results, where the component unrelated to pattern formation appears as a temporal grid, and traveling wave respectively. Frog spinal cord microstimulation with N-methyl-D-Aspartate (NMDA), a CPG activator, produced a limited set of force directions, sometimes tonic, but more often alternating between directions similar to the tonic forces. The tonic forces were topographically organized, and sites evoking rhythms with different force subsets were located close to the constituent tonic force regions. Thus CPGs consist of topographically organized modules. Modularity was also identified as a limited set of muscle synergies whose combinations reconstructed the EMGs. The cat CPG was investigated using proprioceptive inputs during fictive locomotion. Critical points identified both as abrupt transitions in the effect of phasic perturbations, and burst shape transitions, had biomechanical correlates in intact locomotion. During tonic proprioceptive perturbations, discrete shifts between these critical points explained the burst durations changes, and amplitude changes occurred at one of these points. Besides confirming CPG modularity, these results suggest a fixed temporal grid of anchoring points, to shift modules onsets and offsets. Frog locomotion, reconstructed with the NMDA synergies, showed a partially overlapping synergy activation sequence. Using the early synergy output evoked by NMDA at different spinal sites, revealed a rostrocaudal topographic organization, where each synergy is preferentially evoked from a few, albeit overlapping, cord regions. Comparing the locomotor synergy sequence with this topography suggests that a rostrocaudal traveling wave would activate the synergies in the proper sequence for locomotion. This output was reproduced in a two-layer model using this topography and a traveling wave. Together our results suggest two CPG components: modules, i.e., synergies; and temporal patterning, seen as a temporal grid in the cat, and a traveling wave in the frog. Animal and limb navigation have similarities. Research relating grid cells to the theta rhythm and on segmentation during navigation may relate to our temporal grid and traveling wave results. Winfree's mathematical work, combining critical phases and a traveling wave, also appears important. We conclude suggesting tracing, and imaging experiments to investigate our CPG model.

Gonadal abnormalities in frogs (Lithobates spp.) collected from managed wetlands in an agricultural region of Nebraska, USA

USGS Publications Warehouse

Papoulias, Diana M.; Schwarz, Matt S.; Mena, Lourdes

2013-01-01

Nebraska's Rainwater Basin (RWB) provides important wetland habitat for North American migratory birds. Concern exists that pesticide and nutrient runoff from surrounding row-crops enters wetlands degrading water quality and adversely affecting birds and wildlife. Frogs may be especially vulnerable. Plains leopard (Lithobates blairi) metamorphs from RWB wetlands with varying concentrations of pesticides were evaluated for a suite of biomarkers of exposure to endocrine active chemicals. Froglets had ovarian dysgenesis, high rates of testicular oocytes, and female-biased sex ratios however, there was no clear statistical association between pesticide concentrations and biomarkers. Data interpretation was hindered because timing and duration of exposures were unknown and due to an incomplete understanding of L. blairi sexual development. Emphasis is on describing the complex developmental biology of closely-related leopard frogs, how this understanding can explain RWB L. blairi anomalies, and the need for sampling at the appropriate life stage.

Frog tongue surface microstructures: functional and evolutionary patterns

PubMed Central

Gorb, Stanislav N

2016-01-01

Summary Frogs (Lissamphibia: Anura) use adhesive tongues to capture fast moving, elusive prey. For this, the tongues are moved quickly and adhere instantaneously to various prey surfaces. Recently, the functional morphology of frog tongues was discussed in context of their adhesive performance. It was suggested that the interaction between the tongue surface and the mucus coating is important for generating strong pull-off forces. However, despite the general notions about its importance for a successful contact with the prey, little is known about the surface structure of frog tongues. Previous studies focused almost exclusively on species within the Ranidae and Bufonidae, neglecting the wide diversity of frogs. Here we examined the tongue surface in nine different frog species, comprising eight different taxa, i.e., the Alytidae, Bombinatoridae, Megophryidae, Hylidae, Ceratophryidae, Ranidae, Bufonidae, and Dendrobatidae. In all species examined herein, we found fungiform and filiform papillae on the tongue surface. Further, we observed a high degree of variation among tongues in different frogs. These differences can be seen in the size and shape of the papillae, in the fine-structures on the papillae, as well as in the three-dimensional organization of subsurface tissues. Notably, the fine-structures on the filiform papillae in frogs comprise hair-like protrusions (Megophryidae and Ranidae), microridges (Bufonidae and Dendrobatidae), or can be irregularly shaped or absent as observed in the remaining taxa examined herein. Some of this variation might be related to different degrees of adhesive performance and may point to differences in the spectra of prey items between frog taxa. PMID:27547606

Phylogenomics reveals rapid, simultaneous diversification of three major clades of Gondwanan frogs at the Cretaceous–Paleogene boundary

PubMed Central

Feng, Yan-Jie; Liang, Dan; Hillis, David M.; Cannatella, David C.; Zhang, Peng

2017-01-01

Frogs (Anura) are one of the most diverse groups of vertebrates and comprise nearly 90% of living amphibian species. Their worldwide distribution and diverse biology make them well-suited for assessing fundamental questions in evolution, ecology, and conservation. However, despite their scientific importance, the evolutionary history and tempo of frog diversification remain poorly understood. By using a molecular dataset of unprecedented size, including 88-kb characters from 95 nuclear genes of 156 frog species, in conjunction with 20 fossil-based calibrations, our analyses result in the most strongly supported phylogeny of all major frog lineages and provide a timescale of frog evolution that suggests much younger divergence times than suggested by earlier studies. Unexpectedly, our divergence-time analyses show that three species-rich clades (Hyloidea, Microhylidae, and Natatanura), which together comprise ∼88% of extant anuran species, simultaneously underwent rapid diversification at the Cretaceous–Paleogene (K–Pg) boundary (KPB). Moreover, anuran families and subfamilies containing arboreal species originated near or after the KPB. These results suggest that the K–Pg mass extinction may have triggered explosive radiations of frogs by creating new ecological opportunities. This phylogeny also reveals relationships such as Microhylidae being sister to all other ranoid frogs and African continental lineages of Natatanura forming a clade that is sister to a clade of Eurasian, Indian, Melanesian, and Malagasy lineages. Biogeographical analyses suggest that the ancestral area of modern frogs was Africa, and their current distribution is largely associated with the breakup of Pangaea and subsequent Gondwanan fragmentation. PMID:28673970

Phylogenomics reveals rapid, simultaneous diversification of three major clades of Gondwanan frogs at the Cretaceous-Paleogene boundary.

PubMed

Feng, Yan-Jie; Blackburn, David C; Liang, Dan; Hillis, David M; Wake, David B; Cannatella, David C; Zhang, Peng

2017-07-18

Frogs (Anura) are one of the most diverse groups of vertebrates and comprise nearly 90% of living amphibian species. Their worldwide distribution and diverse biology make them well-suited for assessing fundamental questions in evolution, ecology, and conservation. However, despite their scientific importance, the evolutionary history and tempo of frog diversification remain poorly understood. By using a molecular dataset of unprecedented size, including 88-kb characters from 95 nuclear genes of 156 frog species, in conjunction with 20 fossil-based calibrations, our analyses result in the most strongly supported phylogeny of all major frog lineages and provide a timescale of frog evolution that suggests much younger divergence times than suggested by earlier studies. Unexpectedly, our divergence-time analyses show that three species-rich clades (Hyloidea, Microhylidae, and Natatanura), which together comprise ∼88% of extant anuran species, simultaneously underwent rapid diversification at the Cretaceous-Paleogene (K-Pg) boundary (KPB). Moreover, anuran families and subfamilies containing arboreal species originated near or after the KPB. These results suggest that the K-Pg mass extinction may have triggered explosive radiations of frogs by creating new ecological opportunities. This phylogeny also reveals relationships such as Microhylidae being sister to all other ranoid frogs and African continental lineages of Natatanura forming a clade that is sister to a clade of Eurasian, Indian, Melanesian, and Malagasy lineages. Biogeographical analyses suggest that the ancestral area of modern frogs was Africa, and their current distribution is largely associated with the breakup of Pangaea and subsequent Gondwanan fragmentation.

How the environment shapes animal signals: a test of the acoustic adaptation hypothesis in frogs.

PubMed

Goutte, S; Dubois, A; Howard, S D; Márquez, R; Rowley, J J L; Dehling, J M; Grandcolas, P; Xiong, R C; Legendre, F

2018-01-01

Long-distance acoustic signals are widely used in animal communication systems and, in many cases, are essential for reproduction. The acoustic adaptation hypothesis (AAH) implies that acoustic signals should be selected for further transmission and better content integrity under the acoustic constraints of the habitat in which they are produced. In this study, we test predictions derived from the AAH in frogs. Specifically, we focus on the difference between torrent frogs and frogs calling in less noisy habitats. Torrents produce sounds that can mask frog vocalizations and constitute a major acoustic constraint on call evolution. We combine data collected in the field, material from scientific collections and the literature for a total of 79 primarily Asian species, of the families Ranidae, Rhacophoridae, Dicroglossidae and Microhylidae. Using phylogenetic comparative methods and including morphological and environmental potential confounding factors, we investigate putatively adaptive call features in torrent frogs. We use broad habitat categories as well as fine-scale habitat measurements and test their correlation with six call characteristics. We find mixed support for the AAH. Spectral features of torrent frog calls are different from those of frogs calling in other habitats and are related to ambient noise levels, as predicted by the AAH. However, temporal call features do not seem to be shaped by the frogs' calling habitats. Our results underline both the complexity of call evolution and the need to consider multiple factors when investigating this issue. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Population estimates for the Toiyabe population of the Columbia spotted frog (Rana luteiventris), 2004–10

USGS Publications Warehouse

Adams, Michael J.; Mellison, Chad; Galvan, Stephanie K.

2013-01-01

The Toiyabe population of Columbia spotted frogs (Rana luteiventris, hereafter "Toiyabe frogs") is a geographically isolated population located in central Nevada (fig. 1). The Toiyabe population is part of the Great Basin Distinct Population Segment of Columbia spotted frogs, and is a candidate for listing under the Endangered Species Act (U.S. Fish and Wildlife Service, 2011). The cluster of breeding sites in central Nevada represents the southernmost extremity of the Columbia spotted frogs' known range (Funk and others, 2008). Toiyabe frogs are known to occur in seven drainages in Nye County, Nevada: Reese River, Cow Canyon Creek, Ledbetter Canyon Creek, Cloverdale Creek, Stewart Creek, Illinois Creek, and Indian Valley Creek. Most of the Toiyabe frog population resides in the Reese River, Indian Valley Creek, and Cloverdale Creek drainages (fig. 1; Nevada Department of Wildlife, 2003). Approximately 90 percent of the Toiyabe frogs' habitat is on public land. Most of the public land habitat (95 percent) is managed by the U.S. Forest Service (USFS), while the Bureau of Land Management (BLM) manages the remainder. Additional Toiyabe frog habitat is under Yomba Shoshone Tribal management and in private ownership (Nevada Department of Wildlife, 2003). The BLM, USFS, Nevada Department of Wildlife (NDOW), Nevada Natural Heritage Program (NNHP), Nye County, and U.S Fish and Wildlife Service (USFWS) have monitored the Toiyabe population since 2004 using mark and recapture surveys (Nevada Department of Wildlife, 2004). The USFWS contracted with the U.S. Geological Survey (USGS) to produce population estimates using these data.

Peatlands and green frogs: A relationship regulated by acidity?

USGS Publications Warehouse

Mazerolle, M.J.

2005-01-01

The effects of site acidification on amphibian populations have been thoroughly addressed in the last decades. However, amphibians in naturally acidic environments, such as peatlands facing pressure from the peat mining industry, have received little attention. Through two field studies and an experiment, I assessed the use of bog habitats by the green frog (Rana clamitans melanota), a species sensitive to various forestry and peat mining disturbances. First, I compared the occurrence and breeding patterns of frogs in bog and upland ponds. I then evaluated frog movements between forest and bog habitats to determine whether they corresponded to breeding or postbreeding movements. Finally, I investigated, through a field experiment, the value of bogs as rehydrating areas for amphibians by offering living Sphagnum moss and two media associated with uplands (i.e., water with pH ca 6.5 and water-saturated soil) to acutely dehydrated frogs. Green frog reproduction at bog ponds was a rare event, and no net movements occurred between forest and bog habitats. However, acutely dehydrated frogs did not avoid Sphagnum. Results show that although green frogs rarely breed in bogs and do not move en masse between forest and bog habitats, they do not avoid bog substrates for rehydrating, despite their acidity. Thus, bogs offer viable summering habitat to amphibians, which highlights the value of these threatened environments in terrestrial amphibian ecology.

Landscape resistance to frog movements

USGS Publications Warehouse

Mazerolle, M.J.; Desrochers, A.

2005-01-01

An animal's capacity to recolonize a patch depends on at least two components: its ability to detect the patch and its ability to reach it. However, the disruption of such processes by anthropic disturbances could explain low animal abundance patterns observed by many investigators in certain landscapes. Through field experiments, we compared the orientation and homing success of northern green frogs (Rana clamitans melanota Rafinesque, 1820) and northern leopard frogs (Rana pipiens Schreber, 1782) translocated across disturbed or undisturbed surfaces. We also monitored the path selected by individuals when presented with a choice between a short distance over a disturbed surface and a longer, undisturbed route. Finally, we measured the water loss and behaviour of frogs on substrates resulting from anthropogenic disturbances and a control. When presented with a choice, 72% of the frogs avoided disturbed surfaces. Although able to orient towards the pond of capture when translocated on disturbed surfaces, frogs had a lower probability of homing successfully to the pond than when translocated at a similar distance on an undisturbed surface. Frogs lost the most water on substrates associated with disturbance and in the absence of cover. Our data illustrate that anthropically disturbed areas devoid of cover, such as mined peatlands and agricultural fields, disrupt the ability of frogs to reach habitat patches and are likely explanations to their reduced abundance patterns in such environments. ?? 2005 NRC Canada.

Frog species richness, composition and beta-diversity in coastal Brazilian restinga habitats.

PubMed

Rocha, C F D; Hatano, F H; Vrcibradic, D; Van Sluys, M

2008-02-01

We studied the species richness and composition of frogs in 10 restinga habitats (sand dune environments dominated by herbaceous and shrubby vegetation) along approximately 1500 km of coastal areas of three Brazilian States: Rio de Janeiro (Grumari, Maricá, Massambaba, Jurubatiba and Grussaí), Espírito Santo (Praia das Neves and Setiba) and Bahia (Prado and Trancoso). We estimated beta-diversity and similarity among areas and related these parameters to geographic distance between areas. All areas were surveyed with a similar sampling procedure. We found 28 frog species belonging to the families Hylidae, Microhylidae, Leptodactylidae and Bufonidae. Frogs in restingas were in general nocturnal with no strictly diurnal species. The richest restinga was Praia das Neves (13 species), followed by Grussaí and Trancoso (eight species in each). The commonest species in the restingas was Scinax alter (found in eight restingas), followed by Aparasphenodon brunoi (seven areas). Our data shows that richness and composition of frog communities vary consistently along the eastern Brazilian coast and, in part, the rate of species turnover is affected by the distance among areas. Geographic distance explained approximately 12% of species turnover in restingas and about 9.5% of similarity among frog assemblages. Although geographic distance somewhat affects frog assemblages, other factors (e.g. historical factors, disturbances) seem to be also involved in explaining present frog assemblage composition in each area and species turnover among areas. The frog fauna along restinga habitats was significantly nested (matrix community temperature = 26.13 degrees; p = 0.007). Our data also showed that the most hospitable restinga was Praia das Neves and indicated that this area should be protected as a conservation unit. Frog assemblage of each area seems to partially represent a nested subset of the original assemblage, although we should not ignore the importance of historical factors. This nestedness pattern, in part, probably results from the intensive fragmentation of restinga habitats. Possibly, many frog species may have been lost in some studied areas as a result of the extensive habitat degradation to which restinga habitats are presently exposed.

Field surveys of Midwestern and Northeastern Fish and Wildlife Service lands for the presence of abnormal frogs and toads

USGS Publications Warehouse

Converse, K.A.; Mattsson, J.; Eaton-Poole, L.

2000-01-01

The national distribution of information on the discovery of malformations in Minnesota frogs in 1995 stimulated collection and examination of newly metamorphosed frogs during 1996. By late summer and early fall of 1996, malformed frogs and toads were reported on U.S. Fish and Wildlife Service (USFWS) lands in Vermont (Northeast, Region 5) and Minnesota (Midwest, Region 3). In response to these reports, biologists in USFWS Regions 3 and 5 conducted a survey, during the summer of 1997 to determine the distribution and type of malformations in frogs and toads on selected federal lands. Region 3 personnel surveyed 38 field stations at National Wildlife Refuges (NWR's) and Wetland Management Districts. Malformed frogs and toads were collected at 23 (61%) of the Region 3 sites. External malformations were detected in 110 of 6632 individuals representing seven of 13 frog species and one of three toad species examined for an overall of 1.7% affected (percentages for affected species ranged from 0.4-5.2%). In Region 5, 17 NWR's and one National Park were surveyed. Malformed frogs were collected at 10 (56%) of the Region 5 sites. External malformations were detected in 58 of 2267 individuals representing six of 11 frog species and one of two toad species examined for an overall total of 2.6% affected (percentages for affected species ranged from 1.8-15.6%). The majority of malformations observed in frogs and toads collected in Regions 3 and 5 were partially or completely missing hind limbs and digits (50%)or malformed hind limbs and digits (14%). A few individuals had an extra limb or toe, missing or malformed front limb, missing eye, or malformation of the mandible. Despite small sample sizes at some sites, malformations were confirmed to be present in eight species of frogs and two species of toads on Federal lands in USFWS Regions 3 and 5. Further study is needed to determine the extent and distribution of amphibian malformations in these Regions. Data from this study were provided to the national database on distribution of malformed amphibians.

How to Comply with Requirements to Protect California Red-legged Frog from Pesticides

EPA Pesticide Factsheets

This document describes buffer areas around certain habitats of the California red-legged frog, and limits on use of certain pesticides within those habitats and buffer zones to protect the red-legged frog from certain pesticides.

Extremely low prevalence of Batrachochytrium dendrobatidis in frog populations from neotropical dry forest of Costa Rica supports the existence of a climatic refuge from disease.

PubMed

Zumbado-Ulate, Héctor; Bolaños, Federico; Gutiérrez-Espeleta, Gustavo; Puschendorf, Robert

2014-12-01

Population declines and extinctions of numerous species of amphibians, especially stream-breeding frogs, have been linked to the emerging infectious disease chytridiomycosis, caused by the chytrid fungus, Batrachochytrium dendrobatidis. In Central America, most of the 34 species of the Craugastor punctariolus species group have disappeared in recent years in high- and low-elevation rainforests. Distribution models for B. dendrobatidis and the continuous presence of the extirpated stream-dwelling species, Craugastor ranoides, in the driest site of Costa Rica (Santa Elena Peninsula), suggest that environmental conditions might restrict the growth and development of B. dendrobatidis, existing as a refuge from chytridiomycosis-driven extinction. We conducted field surveys to detect and quantify the pathogen using Real-time PCR in samples from 15 species of frogs in two locations of tropical dry forest. In Santa Elena Peninsula, we swabbed 310 frogs, and only one sample of the species, C. ranoides, tested positive for B. dendrobatidis (prevalence <0.1%). In Santa Rosa Station, we swabbed 100 frogs, and nine samples from three species tested positive (prevalence = 9.0%). We failed to detect signs of chytridiomycosis in any of the 410 sampled frogs, and low quantities of genetic equivalents (between 0 and 1073) were obtained from the ten positive samples. The difference in the prevalence between locations might be due not only to the hotter and drier conditions of Santa Elena Peninsula but also to the different compositions of species in both locations. Our results suggest that B. dendrobatidis is at the edge of its distribution in these dry and hot environments of tropical dry forest. This study supports the existence of climatic refuges from chytridiomycosis and highlights the importance of tropical dry forest conservation for amphibians in the face of epidemic disease.

The wood frog (Rana sylvatica): a technical conservation assessment

USGS Publications Warehouse

Muths, E.; Rittmann, S.; Irwin, J.; Keinath, D.; Scherer, R.

2005-01-01

Overall, the wood frog (Rana sylvatica) is ranked G5, secure through most of its range (NatureServe Explorer 2002). However, it is more vulnerable in some states within the USDA Forest Service Region 2: S3 (vulnerable) in Colorado, S2 (imperiled) in Wyoming, and S1 (critically imperiled in South Dakota (NatureServe Explorer 2002); there are no records for wood frogs in Kansas or Nebraska. Primary threats to wood frog populations are habitat fragmentation (loss of area, edge effects, and isolation) and habitat loss due to anthropogenic causes (e.g., wetland draining, grazing) and natural changes as habitat succession occurs. Wood frogs are most conspicuous at breeding sites early in the spring, when snow and ice are often still present at pond margins. They tolerate frezzing and hibernate terrestrially in shallow depressions, under leaf litter, grasses, logs, or rocks (Bagdonas 1968, Bellis 1961a); there are no reports of aquatic hibernation for this species (Licht 1991, Pinder et al. 1992). Wood frogs require semi-permanent and temporary pools of natural origin and adjacent wet meadows, and landscape alterations that shorten the hydroperiod of ponds can result in catastrophic tadpole mortality. Plant communities utilized by wood frogs in the Rocky Mountains are hydric to mesic and include sedge and grass meadows, willow hummocks, aspen groves, lodgepole pine forests, and woodlands with leaf litter and/or herbaceous understory (Maslin 1947, Bellis 1961a, Roberts and Lewin 1979, Haynes and Aird 1981). Wood frogs are likely to disperse into surrounding marsh and woodlands soon after oviposition (Heatwole 1961, Haynes and Aird 1981). In the arly fall, wood frogs begin to seek hibernacula at or just below the ground surface, generally in upland forest habitat (Regosin et al. 2003). Licht (1991) demonstrated shelter-seeking behavior at 1.5 [degrees] C. Once they have concealed themselves for hibernation, wood frogs are very difficult to detecta?|

Stable isotope analyses-A method to distinguish intensively farmed from wild frogs.

PubMed

Dittrich, Carolin; Struck, Ulrich; Rödel, Mark-Oliver

2017-04-01

Consumption of frog legs is increasing worldwide, with potentially dramatic effects for ecosystems. More and more functioning frog farms are reported to exist. However, due to the lack of reliable methods to distinguish farmed from wild-caught individuals, the origin of frogs in the international trade is often uncertain. Here, we present a new methodological approach to this problem. We investigated the isotopic composition of legally traded frog legs from suppliers in Vietnam and Indonesia. Muscle and bone tissue samples were examined for δ 15 N, δ 13 C, and δ 18 O stable isotope compositions, to elucidate the conditions under which the frogs grew up. We used DNA barcoding (16S rRNA) to verify species identities. We identified three traded species ( Hoplobatrachus rugulosus, Fejervarya cancrivora and Limnonectes macrodon ); species identities were partly deviating from package labeling. Isotopic values of δ 15 N and δ 18 O showed significant differences between species and country of origin. Based on low δ 15 N composition and generally little variation in stable isotope values, our results imply that frogs from Vietnam were indeed farmed. In contrast, the frogs from the Indonesian supplier likely grew up under natural conditions, indicated by higher δ 15 N values and stronger variability in the stable isotope composition. Our results indicate that stable isotope analyses seem to be a useful tool to distinguish between naturally growing and intensively farmed frogs. We believe that this method can be used to improve the control in the international trade of frog legs, as well as for other biological products, thus supporting farming activities and decreasing pressure on wild populations. However, we examined different species from different countries and had no access to samples of individuals with confirmed origin and living conditions. Therefore, we suggest improving this method further with individuals of known origin and history, preferably including samples of the respective nutritive bases.

STS-47 MS Jemison trains in SLJ module at MSFC Payload Crew Training Complex

NASA Technical Reports Server (NTRS)

1992-01-01

STS-47 Endeavour, Orbiter Vehicle (OV) 105, Mission Specialist (MS) Mae C. Jemison, wearing Autogenic Feedback Training System 2 suit, works with the Frog Embryology Experiment in a General Purpose Workstation (GPWS) in the Spacelab Japan (SLJ) module mockup at the Payload Crew Training Complex. The experiment will study the effects of weightlessness on the development of frog eggs fertilized in space. The Payload Crew Training Complex is located at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama. View provided with alternate number 92P-139.

Forms and prevalence of intersexuality and effects of environmental contaminants on sexuality in cricket frogs (Acris crepitans).

PubMed Central

Reeder, A L; Foley, G L; Nichols, D K; Hansen, L G; Wikoff, B; Faeh, S; Eisold, J; Wheeler, M B; Warner, R; Murphy, J E; Beasley, V R

1998-01-01

Cricket frogs (Acris crepitans) from several different sites in Illinois were collected to assess the effects of environmental contamination on the prevalence of intersex gonads. Of 341 frogs collected in 1993, 1994, and 1995, 2.7% were intersex individuals. There was no statistically significant relationship between the chemical compounds detected and cricket frog intersexuality. However, there was an association approaching significance (p = 0.07) between the detection of atrazine and intersex individuals. A comparison of reference sites with sites that had point polychlorinated biphenyl (PCB) and polychlorinated dibenzofuran (PCDF) contamination revealed a significant relationship between sex-ratio reversal and contamination with PCBs and PCDFs. The sex ratio of juvenile frogs studied from three sites with PCB and PCDF point contamination favored males over females, which was the opposite of the sex ratio in control ponds (p = 0.0007). The statistically significant correlation between organochlorine contamination and sex-ratio reversal suggests PCBs and PCDFs can influence cricket frog sexual differentiation. The current study suggests that in cricket frogs, sex ratios and the prevalence of intersex gonads are altered by environmental contamination. Images Figure 1 Figure 2 PMID:9647894

Asymmetrical effects of introduced Rana catesbeiana on native ranid frogs in Oregon, USA

USGS Publications Warehouse

Pearl, Christopher A.; Adams, Michael J.; Bury, R. Bruce; McCreary, B.

2004-01-01

Introduced American Bullfrogs (Rana catesbeiana) have become widely established in the Pacific Northwest over the last century and are thought to be an important predator of native amphibians throughout the western United States. The Northern Red-Legged Frog (Rana aurora aurora) and Oregon Spotted Frog (Rana pretiosa) historically coexisted in portions of the Pacific Northwest now invaded by R. catesbeiana, but R. pretiosa has declined more severely than R. a. aurora. We investigated whether microhabitat and behavioral differences that facilitate sympatric coexistence of the natives predict which species is more susceptible to predation by introduced R. catesbeiana. Our laboratory experiments demonstrate that R. catesbeiana adults prefer aquatic microhabitats, that R. pretiosa juveniles are more aquatic than R. a. aurora, and that adult R. catesbeiana consume more R. pretiosa than R. a. aurora juveniles. Mean and maximum jump distances of R. pretiosa were shorter than equally sized R. a. aurora, and the difference between these two species increased with larger frog sizes. Our examination of field survey data indicates that R. pretiosa coexist with R. catesbeiana less frequently than R. a. aurora. We conclude that R. catesbeiana is a greater threat to survival of R. pretiosa than to R. a. aurora and suggest that microhabitat use and escape abilities of native ranid frogs may be linked to this asymmetrical effect. Analysis of behavioral and microhabitat differences among related native species may be a useful tool in predicting the effects of introduced predators on amphibians and can assist in developing conservation priorities for these species.

Asymmetrical Effects of Introduced Bullfrogs (Rana catesbeiana) on Native Ranid Frogs in Oregon

USGS Publications Warehouse

Pearl, C.A.; Adams, M.J.; Bury, R.B.; McCreary, B.

2004-01-01

Introduced American Bullfrogs (Rana catesbeiana) have become widely established in the Pacific Northwest over the last century and are thought to be an important predator of native amphibians throughout the western United States. The Northern Red-Legged Frog (Rana aurora aurora) and Oregon Spotted Frog (Rana pretiosa) historically coexisted in portions of the Pacific Northwest now invaded by R. catesbeiana, but R. pretiosa has declined more severely than R. a. aurora. We investigated whether microhabitat and behavioral differences that facilitate sympatric coexistence of the natives predict which species is more susceptible to predation by introduced R. catesbeiana. Our laboratory experiments demonstrate that R. catesbeiana adults prefer aquatic microhabitats, that R. pretiosa juveniles are more aquatic than R. a. aurora, and that adult R. catesbeiana consume more R. pretiosa than R. a. aurora juveniles. Mean and maximum jump distances of R. pretiosa were shorter than equally sized R. a. aurora, and the difference between these two species increased with larger frog sizes. Our examination of field survey data indicates that R. pretiosa coexist with R. catesbeiana less frequently than R. a. aurora. We conclude that R. catesbeiana is a greater threat to survival of R. pretiosa than to R. a. aurora and suggest that microhabitat use and escape abilities of native ranid frogs may be linked to this asymmetrical effect. Analysis of behavioral and microhabitat differences among related native species may be a useful tool in predicting the effects of introduced predators on amphibians and can assist in developing conservation priorities for these species.

Autonomic regulation of mucociliary transport rate in the oesophagus of the frog, Rana temporaria.

PubMed Central

Morley, J; Sanjar, S

1984-01-01

Transport of lead particles along the mucosal surface of the frog oesophagus has been measured by direct observation with the aid of video recording. Electrical stimulation of the vagus nerve increased the rate of particle transport. This acceleration was suppressed by atropine or by hexamethonium. Acetylcholine and other parasympathomimetic agents accelerated particle transport rate. Such acceleration was abolished by atropine. Nicotine increased the rate of particle transport and this effect was suppressed by hexamethonium or by atropine. Atropine did not significantly alter basal particle transport rate. Neither basal particle transport rate nor the response to vagal nerve stimulation were affected by eserine. Adrenaline, noradrenaline or isoprenaline did not affect basal particle transport rate. Adrenaline or noradrenaline were without effect on the increased particle transport rate due to electrical stimulation of the vagus. PMID:6332901

First report of spontaneous chytridiomycosis in frogs in Asia.

PubMed

Une, Yumi; Kadekaru, Sho; Tamukai, Kenichi; Goka, Kouichi; Kuroki, Toshiro

2008-11-20

This is the first report of amphibian chytridiomycosis in Asia. We discovered a lethal outbreak in Japan, among 45 exotic frogs from 18 species kept for breeding by a private owner. Of these 45 frogs, 16 died and another 7 were found to be infected by chytrid fungus Batrachochytrium dendrobatidis (Bd) but survived after treatment. Bd was detected in frogs from 9 species (Lepidobatrachus laevis, Ceratophrys cornuta, C. cranwelli, C. ornata, C. calcarata, Chacophrys pierotti, Occidozyga lima, Leptodactylus pentadactylus and Plethodontohyla tuberata).

Tol2 transposon-mediated transgenesis in Xenopus tropicalis.

PubMed

Hamlet, Michelle R Johnson; Yergeau, Donald A; Kuliyev, Emin; Takeda, Masatoshi; Taira, Masanori; Kawakami, Koichi; Mead, Paul E

2006-09-01

The diploid frog Xenopus tropicalis is becoming a powerful developmental genetic model system. Sequencing of the X. tropicalis genome is nearing completion and several labs are embarking on mutagenesis screens. We are interested in developing insertional mutagenesis strategies in X. tropicalis. Transposon-mediated insertional mutagenesis, once used exclusively in plants and invertebrate systems, is now more widely applicable to vertebrates. The first step in developing transposons as tools for mutagenesis is to demonstrate that these mobile elements function efficiently in the target organism. Here, we show that the Medaka fish transposon, Tol2, is able to stably integrate into the X. tropicalis genome and will serve as a powerful tool for insertional mutagenesis strategies in the frog.

Host and Aquatic Environment Shape the Amphibian Skin Microbiome but Effects on Downstream Resistance to the Pathogen Batrachochytrium dendrobatidis Are Variable

PubMed Central

Jani, Andrea J.; Briggs, Cheryl J.

2018-01-01

Symbiotic microbial communities play key roles in the health and development of their multicellular hosts. Understanding why microbial communities vary among different host species or individuals is an important step toward understanding the diversity and function of the microbiome. The amphibian skin microbiome may affect resistance to the fungal pathogen Batrachochytrium dendrobatidis (Bd). Still, the factors that determine the diversity and composition of the amphibian skin microbiome, and therefore may ultimately contribute to disease resistance, are not well understood. We conducted a two-phase experiment to first test how host and environment shape the amphibian skin microbiome, and then test if the microbiome affects or is affected by Bd infection. Most lab experiments testing assembly of the amphibian skin microbiome so far have compared sterile to non-sterile environments or heavily augmented to non-augmented frogs. A goal of this study was to evaluate, in an experimental setting, realistic potential drivers of microbiome assembly that would be relevant to patterns observed in nature. We tested effects of frog genetic background (2 source populations) and 6 natural lake water sources in shaping the microbiome of the frog Rana sierrae. Water in which frogs were housed affected the microbiome in a manner that partially mimicked patterns observed in natural populations. In particular, frogs housed in water from disease-resistant populations had greater bacterial richness than frogs housed in water from populations that died out due to Bd. However, in the experiment this difference in microbiomes did not lead to differences in host mortality or rates of pathogen load increase. Frog source population also affected the microbiome and, although none of the frogs in this study showed true resistance to infection, host source population had a small effect on the rate of pathogen load increase. This difference in infection trajectories could be due to the observed differences in the microbiome, but could also be due to other traits that differ between frogs from the two populations. In addition to examining effects of the microbiome on Bd, we tested the effect of Bd infection severity on the microbiome. Specifically, we studied a time series of the microbiome over the course of infection to test if the effects of Bd on the microbiome are dependent on Bd infection severity. Although limited to a small subset of frogs, time series analysis suggested that relative abundances of several bacterial phylotypes changed as Bd loads increased through time, indicating that Bd-induced disturbance of the R. sierrae microbiome is not a binary effect but instead is dependent on infection severity. We conclude that both host and aquatic environment help shape the R. sierrae skin microbiome, with links to small changes in disease resistance in some cases, but in this study the effect of Bd on the microbiome was greater than the effect of the microbiome on Bd. Assessment of the microbiome differences between more distantly related populations than those studied here is needed to fully understand the role of the microbiome in resistance to Bd. PMID:29619014

Evaluation of Antimicrobial and Healing Activities of Frog Skin on Guinea Pigs Wounds

PubMed Central

Rezazade Bazaz, Mahere; Mashreghi, Mohammad; Mahdavi Shahri, Nasser; Mashreghi, Mansour; Asoodeh, Ahmad; Behnam Rassouli, Morteza

2015-01-01

Background: Frog skin secretions have potentials against a wide spectrum of bacteria. Also, frog skin compositions have healing properties. Objectives: The aim of this study was to investigate the antibacterial potentials along with healing properties of frog skin Rana ridibunda, a species which thoroughly lives in Iran marshes, as a biological dressing on wounds. Materials and Methods: In this study, excisional wounds, dressed with frog skin, were compared between experimental and control groups of guinea pigs. In the experimental groups, wounds were dressed with the dermal (FS) and epidermal (RFS) sides of fresh frog R. ridibunda skin, while only usual cotton gauze covered the wounds of the control group. Furthermore, microbial samples were taken on different days (0, 3, 5, and 7 days post injury) to count the number of the colony-forming units. Additionally, the microbial penetration test was performed on frog skin and then the progression of wound closure was evaluated. Results: In the microbial studies, the bacterial load considerably declined in the wounds treated with FS and RFS compared with the control wounds. On day 7 post injury, the numbers of the colony-forming units for the FS, RFS, and control groups were 6.75, 105, and 375, respectively. In the penetration test, fresh frog skin showed to be a bacterial resistant dressing. The results revealed that the rate of wound closure in the experimental groups significantly was accelerated in comparison with that in the control group. Conclusions: Our results demonstrated the antimicrobial properties of frog skin as a wound dressing, which has antimicrobial effects per se. This biological dressing shows promise as an effective biological wound dressing insofar as not only is it capable of resisting microbes and accelerating wound healing but also it is cost-effective and easy to use. PMID:26468364

Frog Swarms: Earthquake Precursors or False Alarms?

PubMed Central

Grant, Rachel A.; Conlan, Hilary

2013-01-01

Simple Summary Media reports linking unusual animal behaviour with earthquakes can potentially create false alarms and unnecessary anxiety among people that live in earthquake risk zones. Recently large frog swarms in China and elsewhere have been reported as earthquake precursors in the media. By examining international media reports of frog swarms since 1850 in comparison to earthquake data, it was concluded that frog swarms are naturally occurring dispersal behaviour of juveniles and are not associated with earthquakes. However, the media in seismic risk areas may be more likely to report frog swarms, and more likely to disseminate reports on frog swarms after earthquakes have occurred, leading to an apparent link between frog swarms and earthquakes. Abstract In short-term earthquake risk forecasting, the avoidance of false alarms is of utmost importance to preclude the possibility of unnecessary panic among populations in seismic hazard areas. Unusual animal behaviour prior to earthquakes has been reported for millennia but has rarely been scientifically documented. Recently large migrations or unusual behaviour of amphibians have been linked to large earthquakes, and media reports of large frog and toad migrations in areas of high seismic risk such as Greece and China have led to fears of a subsequent large earthquake. However, at certain times of year large migrations are part of the normal behavioural repertoire of amphibians. News reports of “frog swarms” from 1850 to the present day were examined for evidence that this behaviour is a precursor to large earthquakes. It was found that only two of 28 reported frog swarms preceded large earthquakes (Sichuan province, China in 2008 and 2010). All of the reported mass migrations of amphibians occurred in late spring, summer and autumn and appeared to relate to small juvenile anurans (frogs and toads). It was concluded that most reported “frog swarms” are actually normal behaviour, probably caused by juvenile animals migrating away from their breeding pond, after a fruitful reproductive season. As amphibian populations undergo large fluctuations in numbers from year to year, this phenomenon will not occur on a yearly basis but will depend on successful reproduction, which is related to numerous climatic and geophysical factors. Hence, most large swarms of amphibians, particularly those involving very small frogs and occurring in late spring or summer, are not unusual and should not be considered earthquake precursors. In addition, it is likely that reports of several mass migration of small toads prior to the Great Sichuan Earthquake in 2008 were not linked to the subsequent M = 7.9 event (some occurred at a great distance from the epicentre), and were probably co-incidence. Statistical analysis of the data indicated frog swarms are unlikely to be connected with earthquakes. Reports of unusual behaviour giving rise to earthquake fears should be interpreted with caution, and consultation with experts in the field of earthquake biology is advised. PMID:26479746

Herpetological monitoring and assessment on the Trinity River, Trinity County, California—Final report

USGS Publications Warehouse

Snover, Melissa L.; Adams, Michael J.

2016-06-14

The primary goal of the Trinity River Restoration Program is to rehabilitate the fisheries on the dam-controlled Trinity River. However, maintaining and enhancing other wildlife populations through the restoration initiative is also a key objective. Foothill yellow-legged frogs (Rana boylii) and western pond turtles (Actinemys marmorata) have been identified as important herpetological species on which to focus monitoring efforts due to their status as California state-listed species of concern and potential listing on the U.S. Endangered Species List. We developed and implemented a monitoring strategy for these species specific to the Trinity River with the objectives of establishing baseline values for probabilities of site occupancy, colonization, and local extinction; identifying site characteristics that correlate with the probability of extinction; and estimating overall trends in abundance. Our 3-year study suggests that foothill yellow-legged frogs declined in the probability of site occupancy. Conversely, our results suggest that western pond turtles increased in both abundance and the probability of site occupancy. The short length of our study period makes it difficult to draw firm conclusions, but these results provide much-needed baseline data. Further monitoring and directed studies are required to assess how habitat changes and management decisions relate to the status and trend of these species over the long term.

PHYLOGEOGRAPHY OF RANA YAVAPAIENSIS AND RANA ONCA: PRELIMINARY FINDINGS WITH CONSERVATION IMPLICATIONS

EPA Science Inventory

The closely related aridland frogs Rana onca (Relict Leopard Frog) and Rana yavapaiensis (Lowland Leopard Frog) have both experienced dramatic population declines. Rana onca currently occurs naturally at only 6 disjunct sites in southern Nevada. Rana yavapaiensis is present acros...

Frog Statistics

Science.gov Websites

Whole Frog Project and Virtual Frog Dissection Statistics wwwstats output for January 1 through duplicate or extraneous accesses. For example, in these statistics, while a POST requesting an image is as well. Note that this under-represents the bytes requested. Starting date for following statistics

Frankixalus, a New Rhacophorid Genus of Tree Hole Breeding Frogs with Oophagous Tadpoles

PubMed Central

Biju, S. D.; Mahony, Stephen; Kamei, Rachunliu G.; Thomas, Ashish; Shouche, Yogesh; Raxworthy, Christopher J.; Meegaskumbura, Madhava; Bocxlaer, Ines Van

2016-01-01

Despite renewed interest in the biogeography and evolutionary history of Old World tree frogs (Rhacophoridae), this family still includes enigmatic frogs with ambiguous phylogenetic placement. During fieldwork in four northeastern states of India, we discovered several populations of tree hole breeding frogs with oophagous tadpoles. We used molecular data, consisting of two nuclear and three mitochondrial gene fragments for all known rhacophorid genera, to investigate the phylogenetic position of these new frogs. Our analyses identify a previously overlooked, yet distinct evolutionary lineage of frogs that warrants recognition as a new genus and is here described as Frankixalus gen. nov. This genus, which contains the enigmatic ‘Polypedates’ jerdonii described by Günther in 1876, forms the sister group of a clade containing Kurixalus, Pseudophilautus, Raorchestes, Mercurana and Beddomixalus. The distinctiveness of this evolutionary lineage is also corroborated by the external morphology of adults and tadpoles, adult osteology, breeding ecology, and life history features. PMID:26790105

Reduced body condition and enzymatic alterations in frogs inhabiting intensive crop production areas.

PubMed

Brodeur, Julie C; Suarez, Romina P; Natale, Guillermo S; Ronco, Alicia E; Elena Zaccagnini, Maria

2011-07-01

Parameters indicative of general condition and health were compared amongst adult frogs inhabiting uncultivated lands and fields subjected to agricultural practices typical of the humid pampas of Argentina. Whereas no significant differences existed in the parasite load and external malformations prevalence rate of adult frogs from either environments, a reduced condition factor was clearly demonstrated in frogs from agricultural lands. This conclusion was reached for four frog species of different life habits: the terrestrial fossorial Rhinella fernandezae, the terrestrial Leptodactylus latinasus, the semi-aquatic Leptodactylus ocellatus, and the arborescent Hypsiboas pulchellus. A distinct pattern of enzymatic modifications was furthermore observed in L. ocellatus and H. pulchellus from agricultural lands, including elevated hepatic activities of catalase and cholinesterase, and an inhibition of liver GST activity. Further studies should investigate the causes and consequences of the systematically low condition factor observed in frogs from agricultural fields of the humid pampas of Argentina. Copyright © 2011 Elsevier Inc. All rights reserved.

An Effective Hybrid Cuckoo Search Algorithm with Improved Shuffled Frog Leaping Algorithm for 0-1 Knapsack Problems

PubMed Central

Wang, Gai-Ge; Feng, Qingjiang; Zhao, Xiang-Jun

2014-01-01

An effective hybrid cuckoo search algorithm (CS) with improved shuffled frog-leaping algorithm (ISFLA) is put forward for solving 0-1 knapsack problem. First of all, with the framework of SFLA, an improved frog-leap operator is designed with the effect of the global optimal information on the frog leaping and information exchange between frog individuals combined with genetic mutation with a small probability. Subsequently, in order to improve the convergence speed and enhance the exploitation ability, a novel CS model is proposed with considering the specific advantages of Lévy flights and frog-leap operator. Furthermore, the greedy transform method is used to repair the infeasible solution and optimize the feasible solution. Finally, numerical simulations are carried out on six different types of 0-1 knapsack instances, and the comparative results have shown the effectiveness of the proposed algorithm and its ability to achieve good quality solutions, which outperforms the binary cuckoo search, the binary differential evolution, and the genetic algorithm. PMID:25404940

Interspecific variation in the phenology of advertisement calling in a temperate Australian frog community.

PubMed

Heard, Geoffrey W; Canessa, Stefano; Parris, Kirsten M

2015-09-01

Spatial and temporal partitioning of resources underlies the coexistence of species with similar niches. In communities of frogs and toads, the phenology of advertisement calling provides insights into temporal partitioning of reproductive effort and its implications for community dynamics. This study assessed the phenology of advertisement calling in an anuran community from Melbourne, in southern Australia. We collated data from 1432 surveys of 253 sites and used logistic regression to quantify seasonality in the nightly probability of calling and the influence of meteorological variables on this probability for six species of frogs. We found limited overlap in the predicted seasonal peaks of calling among these species. Those shown to have overlapping calling peaks are unlikely to be in direct competition, due to differences in larval ecology (Crinia signifera and Litoria ewingii) or differences in calling behavior and acoustics (Limnodynastes dumerilii and Litoria raniformis). In contrast, closely related and ecologically similar species (Crinia signfera and Crinia parinsignifera;Litoria ewingii and Litoria verreauxii) appear to have staggered seasonal peaks of calling. In combination with interspecific variation in the meteorological correlates of calling, these results may be indicative of temporal partitioning of reproductive activity to facilitate coexistence, as has been reported for tropical and temperate anurans from other parts of the globe.

Potential citric acid exposure and toxicity to Hawaiian hoary bats (Lasiurus cinereus semotus) associated with Eleutherodactylus frog control.

PubMed

Pitt, William C; Witmer, Gary W; Jojola, Susan M; Sin, Hans

2014-04-01

We examined potential exposure of Hawaiian hoary bats (Lasiurus cinereus semotus) to citric acid, a minimum risk pesticide registered for control of invasive Eleutherodactylus frog populations. Hoary bats are nocturnal insectivores that roost solitarily in foliage, federally listed as endangered, and are endemic to Hawaii. Oral ingestion during grooming of contaminated fur appears to be the principal route by which these bats might be exposed to citric acid. We made assessments of oral toxicity, citric acid consumption, retention of material on fur, and grooming using big brown bats (Eptesicus fuscus) as a surrogate species. We evaluated both ground application and aerial application of 16 % solutions of citric acid during frog control operations. Absorbent bat effigies exposed to ground and aerial operational spray applications retained means of 1.54 and 0.02 g, respectively, of dry citric acid, although retention by the effigies was much higher than bat carcasses drenched in citric acid solutions. A high dose delivered orally (2,811 mg/kg) was toxic to the big brown bats and emesis occurred in 1 bat dosed as low as the 759 mg/kg level. No effect was observed with the lower doses examined (≤ 542 mg/kg). Bats sprayed with 5 ml of 16 % (w/w) citric acid solution showed no evidence of intoxication. In field situations, it is unlikely that bats would be sprayed directly or ingest much citric acid retained by fur. Based on our observations, we believe Hawaiian hoary bats to be at very low risk from harmful exposure to a toxic dose of citric acid during frog control operations.

Oviduct modifications in foam-nesting frogs, with emphasis on the genus Leptodactylus (Amphibia, Leptodactylidae)

USGS Publications Warehouse

Furness, Andrew I.; McDiarmid, Roy W.; Heyer, W. Ronald; Zug, George R.

2010-01-01

Various species of frogs produce foam nests that hold their eggs during development. We examined the external morphology and histology of structures associated with foam nest production in frogs of the genus Leptodactylus and a few other taxa. We found that the posterior convolutions of the oviducts in all mature female foam-nesting frogs that we examined were enlarged and compressed into globular structures. This organ-like portion of the oviduct has been called a "foam gland" and these structures almost certainly produce the secretion that is beaten by rhythmic limb movements into foam that forms the nest. However, the label "foam gland" is a misnomer because the structures are simply enlarged and tightly folded regions of the pars convoluta of the oviduct, rather than a separate structure; we suggest the name pars convoluta dilata (PCD) for this feature. Although all the foam-nesters we examined had a pars convoluta dilata, its size and shape showed considerable interspecific variation. Some of this variation likely reflects differences in the breeding behaviors among species and in the size, type, and placement of their foam nests. Other variation, particularly in size, may be associated with the physiological periodicity and reproductive state of the female, her age, and/or the number of times she has laid eggs.

Vitamin A values of wild-caught Cuban tree frogs (Osteopilus septentrionalis) and marine toads (Rhinella marina) in whole body, liver, and serum.

PubMed

Sullivan, Kathleen E; Fleming, Greg; Terrell, Scott; Smith, Dustin; Ridgley, Frank; Valdes, Eduardo V

2014-12-01

Recent issues surrounding captive amphibians are often nutritionally related problems, such as hypovitaminosis A. Although supplementation of frogs with vitamin A is a topic of investigation, the underlying issue is understanding vitamin A metabolism in amphibian species. To develop a range of "normal" vitamin A concentrations for captive amphibians, baseline vitamin A concentrations must be established in wild amphibian species. In this study, two species, Cuban tree frogs (Osteopilus septentrionalis; n = 59) and marine toads (Rhinella marina; n = 20) were collected from the wild as part of an invasive species control program at Zoo Miami, Miami, Florida. Serum, liver, and whole body samples were analyzed for vitamin A content. The Cuban tree frogs showed higher concentrations on average of vitamin A in serum (82.8 ppb), liver (248.3 IU/g), and whole body (5474.7 IU/kg) samples compared with marine toads (60.1 ppb; 105.3 IU/g; 940.7 IU/kg, respectively), but differences were not significant (P = 0.22). What can be considered "normal" values of vitamin A concentrations across different amphibian species requires further investigation. Although all amphibians collected in this study appeared healthy, a larger sample size of animals, with known health histories and diets, may provide stronger evidence of normal expectations.

Wild-Caught and Farm-Reared Amphibians are Important Reservoirs of Salmonella, A Study in North-East Thailand.

PubMed

Ribas, A; Poonlaphdecha, S

2017-03-01

The role of amphibians as Salmonella reservoirs has not been as well studied as in reptiles, where the literature is abundant. Recent outbreaks of salmonellosis associated with exotic pet frogs have occurred in United States. Frog farming and wild frog harvesting have increased the international trade in these species. This necessitates a better understanding of the risk of salmonellosis transmission from amphibians to humans. We explored the presence of Salmonella in amphibians (frogs and toads) in Thailand, where farmed and wild frogs as well as toads are present. These live animals are easily found in the local markets and are used as food. Exportation of frog meat from Thailand is common. During March-June 2014, ninety-seven frogs were collected from several habitats, including frog farms, urban areas and protected natural areas. The collected amphibians were tested for the presence of Salmonella. The overall prevalence of Salmonella was 69.07% (90.00% in farm animals, 0% in urban area animals and 44.83% in protected area animals). Eight serovars of Salmonella were isolated: subsp. diarizonae ser. 50:k:z, Hvittingfoss, Muenchen, Newport, Stanley, Thompson, Panama and Wandsworth. Six of the identified serovars, Hvittingfoss, Newport, Panama, Stanley, Thompson and Wandsworth, have been detected in humans in Thailand. According to our results, amphibians are reservoirs of Salmonella and can be a public health concern when used as a source of protein for humans. © 2016 Blackwell Verlag GmbH.

Chasing maximal performance: a cautionary tale from the celebrated jumping frogs of Calaveras County.

PubMed

Astley, H C; Abbott, E M; Azizi, E; Marsh, R L; Roberts, T J

2013-11-01

Maximal performance is an essential metric for understanding many aspects of an organism's biology, but it can be difficult to determine because a measured maximum may reflect only a peak level of effort, not a physiological limit. We used a unique opportunity provided by a frog jumping contest to evaluate the validity of existing laboratory estimates of maximum jumping performance in bullfrogs (Rana catesbeiana). We recorded video of 3124 bullfrog jumps over the course of the 4-day contest at the Calaveras County Jumping Frog Jubilee, and determined jump distance from these images and a calibration of the jump arena. Frogs were divided into two groups: 'rental' frogs collected by fair organizers and jumped by the general public, and frogs collected and jumped by experienced, 'professional' teams. A total of 58% of recorded jumps surpassed the maximum jump distance in the literature (1.295 m), and the longest jump was 2.2 m. Compared with rental frogs, professionally jumped frogs jumped farther, and the distribution of jump distances for this group was skewed towards long jumps. Calculated muscular work, historical records and the skewed distribution of jump distances all suggest that the longest jumps represent the true performance limit for this species. Using resampling, we estimated the probability of observing a given jump distance for various sample sizes, showing that large sample sizes are required to detect rare maximal jumps. These results show the importance of sample size, animal motivation and physiological conditions for accurate maximal performance estimates.

Presence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in threatened corroboree frog populations in the Australian Alps.

PubMed

Hunter, David A; Speare, Rick; Marantelli, Gerry; Mendez, Diana; Pietsch, Rod; Osborne, Will

2010-11-01

Since the early 1980s, the southern corroboree frog Pseudophryne corroboree and northern corroboree frog P. pengilleyi have been in a state of decline from their sub-alpine and high montane bog environments on the southern tablelands of New South Wales, Australia. To date, there has been no adequate explanation as to what is causing the decline of these species. We investigated the possibility that a pathogen associated with other recent frog declines in Australia, the amphibian chytrid fungus Batrachochytrium dendrobatidis, may have been implicated in the decline of the corroboree frogs. We used histology of toe material and real-time PCR of skin swabs to investigate the presence and infection rates with B. dendrobatidis in historic and extant populations of both corroboree frog species. Using histology, we did not detect any B. dendrobatidis infections in corroboree frog populations prior to their decline. However, using the same technique, high rates of infection were observed in populations of both species after the onset of substantial population declines. The real-time PCR screening of skin swabs identified high overall infection rates in extant populations of P. corroboree (between 44 and 59%), while significantly lower rates of infection were observed in low-altitude P. pengilleyi populations (14%). These results suggest that the initial and continued decline of the corroboree frogs may well be attributed to the emergence of B. dendrobatidis in populations of these species.

Urocortins of the South African clawed frog, Xenopus laevis: conservation of structure and function in tetrapod evolution.

PubMed

Boorse, Graham C; Crespi, Erica J; Dautzenberg, Frank M; Denver, Robert J

2005-11-01

Several corticotropin-releasing factor (CRF) family genes have been identified in vertebrates. Mammals have four paralogous genes that encode CRF or the urocortins 1, 2, and 3. In teleost fishes, a CRF, urotensin I (a fish ortholog of mammalian urocortin 1) and urocortin 3 have been identified, suggesting that at least three of the four mammalian lineages arose in a common ancestor of modern bony fishes and tetrapods. Here we report the isolation of genes orthologous to mammalian urocortin 1 and urocortin 3 from the South African clawed frog, Xenopus laevis. We characterize the pharmacology of the frog peptides and show that X. laevis urocortin 1 binds to and activates the frog CRF1 and CRF2 receptors at picomolar concentrations. Similar to mammals, frog urocortin 3 is selective for the CRF2 receptor. Only frog urocortin 1 binds to the CRF-binding protein, although with significantly lower affinity than frog CRF. Both urocortin genes are expressed in brain, pituitary, heart, and kidney of juvenile frogs; urocortin 1 is also expressed in skin. We also identified novel urocortin sequences in the genomes of pufferfish, zebrafish, chicken, and dog. Phylogenetic analysis supports the view that four paralogous lineages of CRF-like peptides arose before the divergence of the actinopterygian and sarcopterygian fishes. Our findings show that the functional relationships among CRF ligands and binding proteins, and their anorexigenic actions mediated by the CRF2 receptor, arose early in vertebrate evolution.

Resurrecting an Extinct Species: Archival DNA, Taxonomy, and Conservation of the Vegas Valley Leopard Frog

EPA Science Inventory

Suggestions that the extinct Vegas Valley leopard frog (Rana fisheri = Lithobates fisheri) may have been synonymous with one of several declining species has complicated recovery planning for imperiled leopard frogs in southwestern North America. To address this concern, we recon...

Teams Explore the Whole Frog

ERIC Educational Resources Information Center

Cessna, Clair E.

1973-01-01

Describes the content and organization of a laboratory session in which student teams work on the organs, tissues, and parasites of a pithed frog. The procedure maximizes participation by every student, makes possible the fullest use of each frog, and permits a rather broad study in a limited time. (JR)

Analysis of veterinary drug residues in frog legs and other aquacultured species using liquid chromatography quadrupole time-of-flight mass spectrometry.

PubMed

Turnipseed, Sherri B; Clark, Susan B; Storey, Joseph M; Carr, Justin R

2012-05-09

A liquid chromatography quadrupole time-of-flight (Q-TOF) mass spectrometry method was developed to analyze veterinary drug residues in frog legs and other aquacultured species. Samples were extracted using a procedure based on a method developed for the analysis of fluoroquinolones (FQs) in fish. Briefly, the tissue was extracted with dilute acetic acid and acetonitrile with added sodium chloride. After centrifugation, the extracts were evaporated and reconstituted in mobile phase. A molecular weight cutoff filter was used to clean up the final extract. A set of target compounds, including trimethoprim, sulfamethoxazole, chloramphenicol, quinolones, and FQs, was used to validate the method. Screening of residues was accomplished by collecting TOF (MS¹) data and comparing the accurate mass and retention times of compounds to a database containing information for veterinary drugs. An evaluation of the MS data in fortified frog legs indicated that the target compounds could be consistently detected at the level of concern. The linearity and recoveries from matrix were evaluated for these analytes to estimate the amount of residue present. MS/MS data were also generated from precursor ions, and the mass accuracy of the product ions for each compound was compared to theoretical values. When the method was used to analyze imported frog legs, many of these residues were found in the samples, often in combination and at relatively high concentrations (>10 ng/g). The data from these samples were also evaluated for nontarget analytes such as residue metabolites and other chemotherapeutics.

Risks to Colombian amphibian fauna from cultivation of coca (Erythroxylum coca): a geographical analysis.

PubMed

Lynch, J D; Arroyo, S B

2009-01-01

The Colombian amphibian fauna is among the richest known in the world, with about 20 species of salamanders (order Caudata), 35 of the limbless caecilians (order Gymnophiona), and more than 700 species of frogs and toads (order Anura) recorded from localities within the country. The potential effects of exposure to glyphosate on amphibians arising from production of illegal crops (coca) were examined. The analysis was based on (1) behavior and ecology of species and (2) proximities of actual museum records to localities in which illegal crops are being grown and the subset of those that have been sprayed with glyphosate. Based on data on the location of amphibians collected in Colombia, records were obtained for 193 species (28% of the national diversity) of frogs and toads found in localities within 10 km of areas where coca is grown. Further analyses with ARC MAP software allowed for measurement of the direct distance separating collection locations for frogs, known coca fields, and areas where aerial spraying was being conducted. Records in or near coca fields included data for 11 of 13 families of frogs and toads known to be present in Colombia. Only Ceratophryidae and Pipidae were not reported from these locations and appear not to be at risk. For eight species (Dendrobates truncatus, Craugastor raniformis, Pristimantis gaigeae, Smilisca phaeota, Elachistocleis ovale, Hypsiboas crepitans, Trachycephalus venulosus, and Pseudis paradoxa) selected to represent several habitat preferences and life-cycle strategies, large areas of their distributions lie outside coca production regions and their populations as a whole are at low risk. For a limited number of species that barely enter Colombian territory, the consequences of coca production may be more serious and may have placed several species of frogs at risk. These include Ameerega bilingua, Dendropsophus bifurcus, Pristimantis colomai, P. degener, P. diadematus, P. quaquaversus, P. variabilis, and Trachycephalus jordani. Other species may also be at risk but exact numbers are unknown since few investigations were undertaken in these areas during the past 30 yr. The main ranges for these species were assumed to be in Ecuador.

Enabling comparative gene expression studies of thyroid hormone action through the development of a flexible real-time quantitative PCR assay for use across multiple anuran indicator and sentinel species.

PubMed

Veldhoen, Nik; Propper, Catherine R; Helbing, Caren C

2014-03-01

Studies performed across diverse frog species have made substantial contributions to our understanding of basic vertebrate development and the natural or anthropogenic environmental factors impacting sensitive life stages. Because, anurans are developmental models, provide ecosystems services, and act as sentinels for the identification of environmental chemical contaminants that interfere with thyroid hormone (TH) action during postembryonic development, there is demand for flexible assessment techniques that can be applied to multiple species. As part of the "thyroid assays across indicator and sentinel species" (TAXISS) initiative, we have designed and validated a series of cross-species real time quantitative PCR (qPCR) primer sets that provide information on transcriptome components in evolutionarily distant anurans. Validation for fifteen gene transcripts involved a rigorous three-tiered quality control within tissue/development-specific contexts. Assay performance was confirmed on multiple tissues (tail fin, liver, brain, and intestine) of Rana catesbeiana and Xenopus laevis tadpoles enabling comparisons between tissues and generation of response profiles to exogenous TH. This revealed notable differences in TH-responsive gene transcripts including thra, thrb, thibz, klf9, col1a2, fn1, plp1, mmp2, timm50, otc, and dio2, suggesting differential regulation and susceptibility to contaminant effects. Evidence for the applicability of the TAXISS anuran qPCR assay across seven other species is also provided with five frog families represented and its utility in defining genome structure was demonstrated. This novel validated approach will enable meaningful comparative studies between frog species and aid in extending knowledge of developmental regulatory pathways and the impact of environmental factors on TH signaling in frog species for which little or no genetic information is currently available. Copyright © 2014 Elsevier B.V. All rights reserved.

Yet More Frogs

ERIC Educational Resources Information Center

Shutler, Paul M. E.

2011-01-01

Extending a recent paper by Derek Holton, we show how to represent the algorithm for the Frog Problem diagrammatically. This diagrammatic representation suggests a simpler proof of the symmetrical case (equal numbers of frogs of each colour) by allowing the even and odd cases to be treated together. It also provides a proof in the asymmetrical…

Coleman Revisited: School Segregation, Peers, and Frog Ponds

ERIC Educational Resources Information Center

Goldsmith, Pat Rubio

2011-01-01

Students from minority segregated schools tend to achieve and attain less than similar students from White segregated schools. This study examines whether peer effects can explain this relationship using normative models and frog-pond models. Normative models (where peers become alike) suggest that minority schoolmates are a liability. Frog-pond…

Ichthyophonus sp. (Ichthyophonae, Ichthyophonida) infection in a South American amphibian, the hylid frog Hypsiboas pulchellus.

PubMed

Borteiro, Claudio; Verdes, José Manuel; Cruz, Juan Carlos; Sabalsagaray, María Jesús; Kolenc, Francisco; Martínez Debat, Claudio; Ubilla, Martín

2015-04-01

We report infection by Ichthyophonus sp. in a South American amphibian, the hylid frog Hypsiboas pulchellus in Uruguay. This frog had a large subcutaneous mass over the urostyle and dorsal musculature comprised of parasitic cysts with mild granulomatous inflammation but otherwise appeared healthy.

Phylogeography of Declining Relict and Lowland Leopard Frogs in the Desert Southwest of North America

EPA Science Inventory

We investigated the phylogeography of the closely related relict leopard frog (Rana onca) and lowland leopard frog (R. yavapaiensis) – two declining anurans from the warm-desert regions of southwestern North America. We used sequence data from two mitochondrial DNA genes to asses...

Semi-automated identification of leopard frogs

USGS Publications Warehouse

Petrovska-Delacrétaz, Dijana; Edwards, Aaron; Chiasson, John; Chollet, Gérard; Pilliod, David S.

2014-01-01

Principal component analysis is used to implement a semi-automatic recognition system to identify recaptured northern leopard frogs (Lithobates pipiens). Results of both open set and closed set experiments are given. The presented algorithm is shown to provide accurate identification of 209 individual leopard frogs from a total set of 1386 images.

First report of Hepatozoon sp. in the Oregon spotted frog, Rana pretiosa.

PubMed

Stenberg, Patricia L; Bowerman, William J

2010-07-01

From 2005 through 2008, we screened 650 Oregon spotted frogs (Rana pretiosa) from three populations in central Oregon, USA, for hemoparasites. A Hepatozoon sp., not previously reported in R. pretiosa, was found in one population of frogs, mostly as intracellular gamonts at a prevalence of 10.5% with parasitemias ranging from 0.02% to greater than 42% of erythrocytes within individual frogs. Intra-and extracellular merozoites were present, but rare. A potential vector, the mosquito Culex boharti, was common throughout the habitat of the population carrying Hepatozoon sp.

High level of cryptic species diversity revealed by sympatric lineages of Southeast Asian forest frogs

PubMed Central

Stuart, Bryan L; Inger, Robert F; Voris, Harold K

2006-01-01

Amphibians tend to exhibit conservative morphological evolution, and the application of molecular and bioacoustic tools in systematic studies have been effective at revealing morphologically ‘cryptic’ species within taxa that were previously considered to be a single species. We report molecular genetic findings on two forest-dwelling ranid frogs from localities across Southeast Asia, and show that sympatric evolutionary lineages of morphologically cryptic frogs are a common pattern. These findings imply that species diversity of Southeast Asian frogs remains significantly underestimated, and taken in concert with other molecular investigations, suggest there may not be any geographically widespread, forest-dwelling frog species in the region. Accurate assessments of diversity and distributions are needed to mitigate extinctions of evolutionary lineages in these threatened vertebrates. PMID:17148433

Formicine ants: An arthropod source for the pumiliotoxin alkaloids of dendrobatid poison frogs

PubMed Central

Saporito, Ralph A.; Garraffo, H. Martin; Donnelly, Maureen A.; Edwards, Adam L.; Longino, John T.; Daly, John W.

2004-01-01

A remarkable diversity of bioactive lipophilic alkaloids is present in the skin of poison frogs and toads worldwide. Originally discovered in neotropical dendrobatid frogs, these alkaloids are now known from mantellid frogs of Madagascar, certain myobatrachid frogs of Australia, and certain bufonid toads of South America. Presumably serving as a passive chemical defense, these alkaloids appear to be sequestered from a variety of alkaloid-containing arthropods. The pumiliotoxins represent a major, widespread, group of alkaloids that are found in virtually all anurans that are chemically defended by the presence of lipophilic alkaloids. Identifying an arthropod source for these alkaloids has been a considerable challenge for chemical ecologists. However, an extensive collection of neotropical forest arthropods has now revealed a putative arthropod source of the pumiliotoxins. Here we report on the presence of pumiliotoxins in formicine ants of the genera Brachymyrmex and Paratrechina, as well as the presence of these ants in the stomach contents of the microsympatric pumiliotoxin-containing dendrobatid frog, Dendrobates pumilio. These pumiliotoxins are major alkaloids in D. pumilio, and Brachymyrmex and Paratrechina ants now represent the only known dietary sources of these toxic alkaloids. These findings further support the significance of ant-specialization and alkaloid sequestration in the evolution of bright warning coloration in poison frogs and toads. PMID:15128938

How spatio-temporal habitat connectivity affects amphibian genetic structure.

PubMed

Watts, Alexander G; Schlichting, Peter E; Billerman, Shawn M; Jesmer, Brett R; Micheletti, Steven; Fortin, Marie-Josée; Funk, W Chris; Hapeman, Paul; Muths, Erin; Murphy, Melanie A

2015-01-01

Heterogeneous landscapes and fluctuating environmental conditions can affect species dispersal, population genetics, and genetic structure, yet understanding how biotic and abiotic factors affect population dynamics in a fluctuating environment is critical for species management. We evaluated how spatio-temporal habitat connectivity influences dispersal and genetic structure in a population of boreal chorus frogs (Pseudacris maculata) using a landscape genetics approach. We developed gravity models to assess the contribution of various factors to the observed genetic distance as a measure of functional connectivity. We selected (a) wetland (within-site) and (b) landscape matrix (between-site) characteristics; and (c) wetland connectivity metrics using a unique methodology. Specifically, we developed three networks that quantify wetland connectivity based on: (i) P. maculata dispersal ability, (ii) temporal variation in wetland quality, and (iii) contribution of wetland stepping-stones to frog dispersal. We examined 18 wetlands in Colorado, and quantified 12 microsatellite loci from 322 individual frogs. We found that genetic connectivity was related to topographic complexity, within- and between-wetland differences in moisture, and wetland functional connectivity as contributed by stepping-stone wetlands. Our results highlight the role that dynamic environmental factors have on dispersal-limited species and illustrate how complex asynchronous interactions contribute to the structure of spatially-explicit metapopulations.

Phenotypic integration mediated by hormones: associations among digit ratios, body size and testosterone during tadpole development.

PubMed

Lofeu, Leandro; Brandt, Renata; Kohlsdorf, Tiana

2017-08-02

Developmental associations often explain phenotypic integration. The intersected hormonal regulation of ontogenetic processes fosters predictions of steroid-mediated phenotypic integration among sexually dimorphic traits, a statement defied by associations between classical dimorphism predictors (e.g. body size) and traits that apparently lack sex-specific functions (e.g. ratios between the lengths of Digits II and IV - 2D:4D). Developmental bases of female-biased 2D:4D have been identified, but these remain unclear for taxa presenting male-biased 2D:4D (e.g. anura). Here we propose two alternative hypotheses to investigate evolution of male-biased 2D:4D associated with sexually dimorphic body size using Leptodactylus frogs: I)'hypothesis of sex-specific digit responses' - Digit IV would be reactive to testosterone but exhibit responses in the opposite direction of those observed in female-biased 2D:4D lineages, so that Digit IV turns shorter in males; II) 'hypothesis of identity of the dimorphic digit'- Digit II would be the dimorphic digit. We compiled the following databases using Leptodactylus frogs: 1) adults of two species from natural populations and 2) testosterone-treated L. fuscus at post-metamorphic stage. Studied traits seem monomorphic in L. fuscus; L. podicipinus exhibits male-biased 2D:4D. When present, 2D:4D dimorphism was male-biased and associated with dimorphic body size; sex differences resided on Digit II instead of IV, corroborating our 'hypothesis of identity of the dimorphic digit'. Developmental steroid roles were validated: testosterone-treated L. fuscus frogs were smaller and exhibited masculinized 2D:4D, and Digit II was the digit that responded to testosterone. We propose a model where evolution of sexual dimorphism in 2D:4D first originates from the advent, in a given digit, of increased tissue sensitivity to steroids. Phenotypic integration with other sexually dimorphic traits would then occur through multi-trait hormonal effects during development. Such process of phenotypic integration seems fitness-independent in its origin and might explain several cases of steroid-mediated integration among sexually dimorphic traits.

A new species of Microkayla (Anura: Craugastoridae: Holoadeninae) from Department La Paz, Bolivia.

PubMed

DE LA Riva, Ignacio; Cortez, Claudia; Burrowes, Patricia A

2017-12-12

We describe a new species of direct-developing frog of the genus Microkayla from the Cordillera Real of the Bolivian Andes, in the Department of La Paz. The new species, Microkayla huayna sp. nov., is closely related to M. teqta and can be distinguished from other species of the genus by its brown dorsal skin and the presence of a large dark brown vocal sac in males. This is the second species of Microkayla known from the Zongo Valley, and the ninth in the Cordillera Real, contributing to a total of 22 described species in Bolivia. Given its small distribution range, we recommend to considering it as Vulnerable according to IUCN criteria.

Persistence of a circadian rhythmicity for thyroid hormones in plasma and thyroid of hibernating male Rana ridibunda.

PubMed

Kühn, E R; Delmotte, N M; Darras, V M

1983-06-01

The presence and circadian rhythmicity of thyroid hormones was studied in plasma and the thyroid gland of male Rana ridibunda before and during hibernation. Hibernating January frogs do have a lower T3 and T4 content of their thyroid gland whereas plasma levels of T3 are maintained and of T4 increased compared to fed September or October frogs. It seems likely that the increased photoperiod in January will be responsible for this increased T4 secretion, since controlled laboratory experiments performed in December did not reveal any influence of low temperature on circulating T3 or T4 levels. Also feeding does not influence circulating levels and thyroid content of thyroid hormones in frogs kept at room temperature during the month of January. A circadian rhythmicity of T3 and T4 in the thyroid gland is present in fed October frogs and in non fed December frogs acclimated at 5 degrees C for 12 days with an acrophase for T3 at approximately 1500 h and for T4 at around 1900 h, whereas in plasma only T3 does have circadian variations (acrophase about midnight) but not T4. When December frogs are acclimated to room temperature for 12 days, frogs are active again, but do not eat and have a lower body weight than frogs hibernating at 5 degrees C. Their T3 content of the thyroid gland has disappeared, but T4 thyroid content and plasma levels of T3 and T4 are maintained. As in hibernating frogs, no circadian variations in T4 plasma concentrations are present whereas the circadian thyroid T4 rhythm disappears. At the same time a dampening in rhythmicity for plasma T3 as judged by the significantly lower amplitude occurs. It is concluded that the persistence of circulating levels of thyroid hormones and of a circadian cyclicity for T3 in plasma in non feeding hibernating frogs may reflect the special metabolic state e.g. availability of food reserves in these animals.

Tribute to R. G. Boutilier: the role for skeletal muscle in the hypoxia-induced hypometabolic responses of submerged frogs.

PubMed

West, T G; Donohoe, P H; Staples, J F; Askew, G N

2006-04-01

Much of Bob Boutilier's research characterised the subcellular, organ-level and in vivo behavioural responses of frogs to environmental hypoxia. His entirely integrative approach helped to reveal the diversity of tissue-level responses to O(2) lack and to advance our understanding of the ecological relevance of hypoxia tolerance in frogs. Work from Bob's lab mainly focused on the role for skeletal muscle in the hypoxic energetics of overwintering frogs. Muscle energy demand affects whole-body metabolism, not only because of its capacity for rapid increases in ATP usage, but also because hypometabolism of the large skeletal muscle mass in inactive animals impacts so greatly on in vivo energetics. The oxyconformance and typical hypoxia-tolerance characteristics (e.g. suppressed heat flux and preserved membrane ion gradients during O(2) lack) of skeletal muscle in vitro suggest that muscle hypoperfusion in vivo is possibly a key mechanism for (i) downregulating muscle and whole-body metabolic rates and (ii) redistributing O(2) supply to hypoxia-sensitive tissues. The gradual onset of a low-level aerobic metabolic state in the muscle of hypoxic, cold-submerged frogs is indeed important for slowing depletion of on-board fuels and extending overwintering survival time. However, it has long been known that overwintering frogs cannot survive anoxia or even severe hypoxia. Recent work shows that they remain sensitive to ambient O(2) and that they emerge rapidly from quiescence in order to actively avoid environmental hypoxia. Hence, overwintering frogs experience periods of hypometabolic quiescence interspersed with episodes of costly hypoxia avoidance behaviour and exercise recovery. In keeping with this flexible physiology and behaviour, muscle mechanical properties in frogs do not deteriorate during periods of overwintering quiescence. On-going studies inspired by Bob Boutilier's integrative mindset continue to illuminate the cost-benefit(s) of intermittent locomotion in overwintering frogs, the constraints on muscle function during hypoxia, the mechanisms of tissue-level hypometabolism, and the details of possible muscle atrophy resistance in quiescent frogs.

Water quality and amphibian health in the Big Bend region of the Rio Grande Basin

USGS Publications Warehouse

Sharma, Bibek; Hu, F.; Carr, J.A.; Patino, Reynaldo

2011-01-01

Male and female Rio Grande leopard frogs (Rana berlandieri) were collected in May 2005 from the main stem and tributaries of the Rio Grande in the Big Bend region of Texas. Frogs were examined for (1) incidence of testicular ovarian follicles in males; (2) thyroid epithelial cell height, a potential index of exposure to thyroid-disrupting contaminants; and (3) incidence of liver melanomacrophage aggregates, a general index of exposure to contaminants. Standard parameters of surface water quality and concentrations of selected elements, including heavy metals, were determined at each frog collection site. Heavy metals also were measured in whole-frog composite extracts. Water cadmium concentrations in most sites and chloride concentrations in the main stem exceeded federal criteria for freshwater aquatic life. Mercury was detected in frogs from the two collection sites in Terlingua Creek. There was a seventeen percent incidence of testicular ovarian follicles in male frogs. Mean thyroid epithelial cell height was greater in frogs from one of the Terlingua Creek sites (Terlingua Abajo). No differences were observed in the incidence of hepatic macrophage aggregates among sites. In conclusion, although potential cause-effect relationships between indices of habitat quality and amphibian health could not be established, the results of this study raise concerns about the general quality of the aquatic habitat and the potential long-term consequences to the aquatic biota of the Big Bend region. The presence of ovarian follicles in male frogs is noteworthy but further study is necessary to determine whether this phenomenon is natural or anthropogenically induced.

Leopard frog PCB levels and evaluation of EROD as a biomarker in Green Bay ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Y.W.; Karasov, W.H.; Patnode, K.P.

1995-12-31

The induction of mixed function oxidases has been shown to be a promising biomarker in many taxa of wildlife, though not yet tested for amphibians. The three hypotheses tested in this study were (1) activities of hepatic EROD of leopard frog (Rana pipiens) are induced following exposure to planar chlorinated PCBs, (2) tissue PCB residue levels of leopard frogs are positively correlated with their wetland sediment PCB levels, and (3) EROD activities are positively correlated with tissue PCB concentrations and sediment PCB. In the laboratory, EROD was increased 2--3 times seven days after i.p. injection with PCB 126 at dosesmore » {ge} 2.3 ppm (wet mass basis). Leopard frogs from seven sites along the Lower Fox River and Green Bay in 1994--1995 were assayed for hepatic EROD activities and total PCB levels in carcasses. Tissue PCB levels ranged from 3 to 152 ppb (including coplanar congeners) and were highest from sites with higher sediment PCB. EROD activity in frogs collected in August--September was not significantly correlated with frog body mass and was similar among sites with one exception. There was no significant correlation between EROD activity and tissue PCB concentration. This result was consistent with the fact that the frogs collected from the Green Bay ecosystem had relatively low PCB levels compared with what was required for induction in the laboratory. The authors conclude that EROD activity is not a sensitive biomarker of PCB exposure in leopard frogs in this ecosystem.« less

Composition of Micro-eukaryotes on the Skin of the Cascades Frog (Rana cascadae) and Patterns of Correlation between Skin Microbes and Batrachochytrium dendrobatidis.

PubMed

Kueneman, Jordan G; Weiss, Sophie; McKenzie, Valerie J

2017-01-01

Global amphibian decline linked to fungal pathogens has galvanized research on applied amphibian conservation. Skin-associated bacterial communities of amphibians have been shown to mediate fungal skin infections and the development of probiotic treatments with antifungal bacteria has become an emergent area of research. While exploring the role of protective bacteria has been a primary focus for amphibian conservation, we aim to expand and study the other microbes present in amphibian skin communities including fungi and other micro-eukaryotes. Here, we characterize skin-associated bacteria and micro-eukaryotic diversity found across life stages of Cascades frog ( Rana cascadae ) and their associated aquatic environments using culture independent 16S and 18S rRNA marker-gene sequencing. Individuals of various life stages of Cascades frogs were sampled from a population located in the Trinity Alps in Northern California during an epidemic of the chytrid fungus, Batrachochytrium dendrobatidis . We filtered the bacterial sequences against a published database of bacteria known to inhibit B. dendrobatidis in co-culture to estimate the proportion of the skin bacterial community that is likely to provide defense against B. dendrobatidis . Tadpoles had a significantly higher proportion of B. dendrobatidis -inhibitory bacterial sequence matches relative to subadult and adult Cascades frogs. We applied a network analysis to examine patterns of correlation between bacterial taxa and B. dendrobatidis , as well as micro-eukaryotic taxa and B. dendrobatidis . Combined with the published database of bacteria known to inhibit B. dendrobatidis , we used the network analysis to identify bacteria that negatively correlated with B. dendrobatidis and thus could be good probiotic candidates in the Cascades frog system.

Effects of carbaryl on green frog (Rana clamitans) tadpoles: Timing of exposure versus multiple exposures

USGS Publications Warehouse

Boone, M.D.; Bridges, C.M.

2003-01-01

The majority of studies on pesticide impacts have evaluated the effects of single exposures. However, multiple exposures to a pesticide may be more prevalent. The objective of our study was to determine how multiple exposures versus single exposure at different times during development affected survival to metamorphosis, tadpole survival, tadpole mass, and tadpole developmental stage of green frog (Rana clamitans) tadpoles reared at low and high density in outdoor cattle tank ponds. Tadpoles were exposed to carbaryl zero, one, two, or three times at 14-d intervals. We applied single doses of carbaryl at one of three times, specifically during early, mid, or late development. Overall, we found that multiple exposures had a greater impact than single exposures during development. More individuals reached metamorphosis in ponds exposed to multiple doses of carbaryl compared with controls, indicating that the presence of carbaryl stimulated metamorphosis. The presence of carbaryl in the aquatic environment also resulted in more developed tadpoles compared with controls. Tadpoles in control ponds did not reach metamorphosis and were less developed than individuals exposed to carbaryl; this effect indicates that, under ideal conditions, green frogs could overwinter in ponds so that greater size could be attained before metamorphosis in the following spring or summer. Our study demonstrated the importance of including realistic application procedures when evaluating the effects of a pesticide and that multiple exposures to a short-lived pesticide are more likely to affect an amphibian population.

Modeling potential river management conflicts between frogs and salmonids

Treesearch

Steven F. Railsback; Bret C. Harvey; Sarah J. Kupferberg; Margaret M. Lang; Scott McBain; Hart H. Welsh

2016-01-01

Management of regulated rivers for yellow-legged frogs (Rana boylii) and salmonids exemplifies potential conflicts among species adapted to different parts of the natural flow and temperature regimes. Yellow-legged frogs oviposit in rivers in spring and depend on declining flows and warming temperatures for egg and tadpole survival and growth,...

49 CFR 213.139 - Spring rail frogs.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Spring rail frogs. 213.139 Section 213.139..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.139 Spring rail frogs. (a) The outer edge of a wheel tread shall not contact the gage side of a spring wing rail. (b) The toe of each...

49 CFR 213.139 - Spring rail frogs.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Spring rail frogs. 213.139 Section 213.139..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.139 Spring rail frogs. (a) The outer edge of a wheel tread shall not contact the gage side of a spring wing rail. (b) The toe of each...

49 CFR 213.139 - Spring rail frogs.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 4 2013-10-01 2013-10-01 false Spring rail frogs. 213.139 Section 213.139..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.139 Spring rail frogs. (a) The outer edge of a wheel tread shall not contact the gage side of a spring wing rail. (b) The toe of each...

49 CFR 213.139 - Spring rail frogs.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 4 2012-10-01 2012-10-01 false Spring rail frogs. 213.139 Section 213.139..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.139 Spring rail frogs. (a) The outer edge of a wheel tread shall not contact the gage side of a spring wing rail. (b) The toe of each...

49 CFR 213.139 - Spring rail frogs.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Spring rail frogs. 213.139 Section 213.139..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.139 Spring rail frogs. (a) The outer edge of a wheel tread shall not contact the gage side of a spring wing rail. (b) The toe of each...

Bacterial flora on Cascades frogs in the Klamath Mountains of California

Treesearch

Karen Pope

2013-01-01

Amphibians are experiencing global declines due in part to the infectious disease chytridiomycosis. Some symbiotic bacteria residents on frog skin have been shown to inhibit the growth of Batrachochytrium dendrobatitis (Bd) but few studies have attempted to fully describe the resident bacterial flora of frog skin. We cultured and sequenced 130...

Propulsive efficiency of frog swimming with different feet and swimming patterns

PubMed Central

Jizhuang, Fan; Wei, Zhang; Bowen, Yuan; Gangfeng, Liu

2017-01-01

ABSTRACT Aquatic and terrestrial animals have different swimming performances and mechanical efficiencies based on their different swimming methods. To explore propulsion in swimming frogs, this study calculated mechanical efficiencies based on data describing aquatic and terrestrial webbed-foot shapes and swimming patterns. First, a simplified frog model and dynamic equation were established, and hydrodynamic forces on the foot were computed according to computational fluid dynamic calculations. Then, a two-link mechanism was used to stand in for the diverse and complicated hind legs found in different frog species, in order to simplify the input work calculation. Joint torques were derived based on the virtual work principle to compute the efficiency of foot propulsion. Finally, two feet and swimming patterns were combined to compute propulsive efficiency. The aquatic frog demonstrated a propulsive efficiency (43.11%) between those of drag-based and lift-based propulsions, while the terrestrial frog efficiency (29.58%) fell within the range of drag-based propulsion. The results illustrate the main factor of swimming patterns for swimming performance and efficiency. PMID:28302669

A Matter of the Heart: The African Clawed Frog Xenopus as a Model for Studying Vertebrate Cardiogenesis and Congenital Heart Defects

PubMed Central

Hempel, Annemarie; Kühl, Michael

2016-01-01

The African clawed frog, Xenopus, is a valuable non-mammalian model organism to investigate vertebrate heart development and to explore the underlying molecular mechanisms of human congenital heart defects (CHDs). In this review, we outline the similarities between Xenopus and mammalian cardiogenesis, and provide an overview of well-studied cardiac genes in Xenopus, which have been associated with congenital heart conditions. Additionally, we highlight advantages of modeling candidate genes derived from genome wide association studies (GWAS) in Xenopus and discuss commonly used techniques. PMID:29367567

Nondestructive Imaging of Internal Structures of Frog (Xenopus laevis) Embryos by Shadow-Projection X-Ray Microtomography

NASA Astrophysics Data System (ADS)

Aoki, Sadao; Yoneda, Ikuo; Nagai, Takeharu; Ueno, Naoto; Murakami, Kazuo

1994-04-01

Nondestructive high-resolution imaging of frog ( Xenopus laevis) embryos has been developed by X-ray microtomography. Shadow-projection X-ray microtomography with a brilliant fine focus laboratory X-ray source could image fine structures of Xenopus embryos which were embedded in paraffin wax. The imaging system enabled us to not only distinguish endoderm from ectoderm at the gastrula stage, but also to obtain a cross-section view of the tail bud embryo showing muscle, notochord and neural tube without staining. Furthermore, the distribution of myosin was also imaged in combination with whole-mount immunohistochemistry.

Effects of Echinostoma trivolvis metacercariae infection during development and metamorphosis of the wood frog (Lithobates sylvaticus).

PubMed

Orlofske, Sarah A; Belden, Lisa K; Hopkins, William A

2017-01-01

Many organisms face energetic trade-offs between defense against parasites and other host processes that may determine overall consequences of infection. These trade-offs may be particularly evident during unfavorable environmental conditions or energetically demanding life history stages. Amphibian metamorphosis, an ecologically important developmental period, is associated with drastic morphological and physiological changes and substantial energetic costs. Effects of the trematode parasite Echinostoma trivolvis have been documented during early amphibian development, but effects during later development and metamorphosis are largely unknown. Using a laboratory experiment, we examined the energetic costs of late development and metamorphosis coupled with E. trivolvis infection in wood frogs, Lithobates [=Rana] sylvaticus. Echinostoma infection intensity did not differ between tadpoles examined prior to and after completing metamorphosis, suggesting that metacercariae were retained through metamorphosis. Infection with E. trivolvis contributed to a slower growth rate and longer development period prior to the initiation of metamorphosis. In contrast, E. trivolvis infection did not affect energy expenditure during late development or metamorphosis. Possible explanations for these results include the presence of parasites not interfering with pronephros degradation during metamorphosis or the mesonephros compensating for any parasite damage. Overall, the energetic costs of metamorphosis for wood frogs were comparable to other species with similar life history traits, but differed from a species with a much shorter duration of metamorphic climax. Our findings contribute to understanding the possible role of energetic trade-offs between parasite defense and host processes by considering parasite infection with simultaneous energetic demands during a sensitive period of development. Copyright © 2016 Elsevier Inc. All rights reserved.

Adaptive Grouping Cloud Model Shuffled Frog Leaping Algorithm for Solving Continuous Optimization Problems

PubMed Central

Liu, Haorui; Yi, Fengyan; Yang, Heli

2016-01-01

The shuffled frog leaping algorithm (SFLA) easily falls into local optimum when it solves multioptimum function optimization problem, which impacts the accuracy and convergence speed. Therefore this paper presents grouped SFLA for solving continuous optimization problems combined with the excellent characteristics of cloud model transformation between qualitative and quantitative research. The algorithm divides the definition domain into several groups and gives each group a set of frogs. Frogs of each region search in their memeplex, and in the search process the algorithm uses the “elite strategy” to update the location information of existing elite frogs through cloud model algorithm. This method narrows the searching space and it can effectively improve the situation of a local optimum; thus convergence speed and accuracy can be significantly improved. The results of computer simulation confirm this conclusion. PMID:26819584

Imparting regenerative capacity to limbs by progenitor cell transplantation

PubMed Central

Lin, Gufa; Chen, Ying; Slack, Jonathan M.W.

2012-01-01

Summary The frog Xenopus can normally regenerate its limbs at early developmental stages but loses the ability during metamorphosis. This behavior provides a potential gain-of-function model for measures that can enhance limb regeneration. Here we show that frog limbs can be caused to form multidigit regenerates after receiving transplants of larval limb progenitor cells. It is necessary to activate Wnt/β -catenin signaling in the cells, and to add Sonic hedgehog, FGF10 and thymosin β4. These factors promote survival and growth of the grafted cells and also provide pattern information. The eventual regenerates are not composed solely of donor tissue; the host cells also make a substantial contribution despite their lack of regeneration-competence. Cells from adult frog legs or from regenerating tadpole tails do not promote limb regeneration, demonstrating the necessity for limb progenitor cells. These findings have obvious implications for the development of a technology to promote limb regeneration in mammals. PMID:23273877

Fitting a Structured Juvenile-Adult Model for Green Tree Frogs to Population Estimates from Capture-Mark-Recapture Field Data

USGS Publications Warehouse

Ackleh, A.S.; Carter, J.; Deng, K.; Huang, Q.; Pal, N.; Yang, X.

2012-01-01

We derive point and interval estimates for an urban population of green tree frogs (Hyla cinerea) from capture-mark-recapture field data obtained during the years 2006-2009. We present an infinite-dimensional least-squares approach which compares a mathematical population model to the statistical population estimates obtained from the field data. The model is composed of nonlinear first-order hyperbolic equations describing the dynamics of the amphibian population where individuals are divided into juveniles (tadpoles) and adults (frogs). To solve the least-squares problem, an explicit finite difference approximation is developed. Convergence results for the computed parameters are presented. Parameter estimates for the vital rates of juveniles and adults are obtained, and standard deviations for these estimates are computed. Numerical results for the model sensitivity with respect to these parameters are given. Finally, the above-mentioned parameter estimates are used to illustrate the long-time behavior of the population under investigation. ?? 2011 Society for Mathematical Biology.

Introducing the Forensic Research/Reference on Genetics knowledge base, FROG-kb.

PubMed

Rajeevan, Haseena; Soundararajan, Usha; Pakstis, Andrew J; Kidd, Kenneth K

2012-09-01

Online tools and databases based on multi-allelic short tandem repeat polymorphisms (STRPs) are actively used in forensic teaching, research, and investigations. The Fst value of each CODIS marker tends to be low across the populations of the world and most populations typically have all the common STRP alleles present diminishing the ability of these systems to discriminate ethnicity. Recently, considerable research is being conducted on single nucleotide polymorphisms (SNPs) to be considered for human identification and description. However, online tools and databases that can be used for forensic research and investigation are limited. The back end DBMS (Database Management System) for FROG-kb is Oracle version 10. The front end is implemented with specific code using technologies such as Java, Java Servlet, JSP, JQuery, and GoogleCharts. We present an open access web application, FROG-kb (Forensic Research/Reference on Genetics-knowledge base, http://frog.med.yale.edu), that is useful for teaching and research relevant to forensics and can serve as a tool facilitating forensic practice. The underlying data for FROG-kb are provided by the already extensively used and referenced ALlele FREquency Database, ALFRED (http://alfred.med.yale.edu). In addition to displaying data in an organized manner, computational tools that use the underlying allele frequencies with user-provided data are implemented in FROG-kb. These tools are organized by the different published SNP/marker panels available. This web tool currently has implemented general functions possible for two types of SNP panels, individual identification and ancestry inference, and a prediction function specific to a phenotype informative panel for eye color. The current online version of FROG-kb already provides new and useful functionality. We expect FROG-kb to grow and expand in capabilities and welcome input from the forensic community in identifying datasets and functionalities that will be most helpful and useful. Thus, the structure and functionality of FROG-kb will be revised in an ongoing process of improvement. This paper describes the state as of early June 2012.

Managing habitat to slow or reverse population declines of the Columbia spotted frog in the Northern Great Basin

USGS Publications Warehouse

Pilliod, David S.; Richard D. Scherer,

2015-01-01

Evaluating the effectiveness of habitat management actions is critical to adaptive management strategies for conservation of imperiled species. We quantified the response of a Great Basin population of the Columbia spotted frog (Rana luteiventris) to multiple habitat improvement actions aimed to reduce threats and reverse population declines. We used mark-recapture data for 1,394 adult frogs that had been marked by state, federal, and university biologists in 9 ponds representing a single population over a 16-year period from 1997 to 2012. With the use of demographic models, we assessed population-level effects of 1) a grazing exclosure constructed around 6 stock ponds that had been used to water livestock for decades before being fully fenced in 2003, and 2) the construction of 3 new stock ponds in 2003 to provide alternative water sources for livestock and, secondarily, to provide additional frog habitat. These management actions were implemented in response to a decline of more than 80% in population size from 1997 to 2002. We found evidence that excluding cattle from ponds and surrounding riparian habitats resulted in higher levels of frog production (more egg masses), higher adult frog recruitment and survival, and higher population growth rate. We also found that frogs colonized the newly constructed stock ponds within 3 years and frogs began breeding in 2 of them after 5 years. The positive effects of the cattle exclosure and additional production from the new ponds, although notable, did not result in full recovery of the population even 9 years later. This slow recovery may be partly explained by the effects of weather on recruitment rates, particularly the negative effects of harsher winters with late springs and higher fall temperatures. Although our findings point to potential successes of habitat management aimed at slowing or reversing rapidly declining frog populations, our study also suggests that recovering from severe population declines can take many years because of demographic and environmental processes. 

Plasticity of peripheral auditory frequency sensitivity in Emei music frog.

PubMed

Zhang, Dian; Cui, Jianguo; Tang, Yezhong

2012-01-01

In anurans reproductive behavior is strongly seasonal. During the spring, frogs emerge from hibernation and males vocalize for mating or advertising territories. Female frogs have the ability to evaluate the quality of the males' resources on the basis of these vocalizations. Although studies revealed that central single torus semicircularis neurons in frogs exhibit season plasticity, the plasticity of peripheral auditory sensitivity in frog is unknown. In this study the seasonally plasticity of peripheral auditory sensitivity was test in the Emei music frog Babina daunchina, by comparing thresholds and latencies of auditory brainstem responses (ABRs) evoked by tone pips and clicks in the reproductive and non-reproductive seasons. The results show that both ABR thresholds and latency differ significantly between the reproductive and non-reproductive seasons. The thresholds of tone pip evoked ABRs in the non-reproductive season increased significantly about 10 dB than those in the reproductive season for frequencies from 1 KHz to 6 KHz. ABR latencies to waveform valley values for tone pips for the same frequencies using appropriate threshold stimulus levels are longer than those in the reproductive season for frequencies from 1.5 to 6 KHz range, although from 0.2 to 1.5 KHz range it is shorter in the non-reproductive season. These results demonstrated that peripheral auditory frequency sensitivity exhibits seasonal plasticity changes which may be adaptive to seasonal reproductive behavior in frogs.

Characterization of kappa 1 and kappa 2 opioid binding sites in frog (Rana esculenta) brain membrane preparation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benyhe, S.; Varga, E.; Hepp, J.

1990-09-01

The distribution and properties of frog brain kappa-opioid receptor subtypes differ not only from those of the guinea pig brain, but also from that of the rat brain. In guinea pig cerebellum the kappa 1 is the dominant receptor subtype, frog brain contains mainly the kappa 2 subtype, and the distribution of the rat brain subtypes is intermediate between the two others. In competition experiments it has been established that ethylketocyclazocine and N-cyclopropylmethyl-norazidomorphine, which are nonselective kappa-ligands, have relatively high affinities to frog brain membranes. The kappa 2 ligands (Met5)enkephalin-Arg6-Phe7 and etorphine also show high affinities to the frog brain.more » Kappa 1 binding sites measured in the presence of 5 microM/D-Ala2-Leu5/enkephalin represent 25-30% of (3H)ethylketocyclazocine binding in frog brain membranes. The kappa 2 subtype in frog brain resembles more to the mu subtype than the delta subtype of opioid receptors, but it differs from the mu subtype in displaying low affinity toward beta-endorphin and /D-Ala2-(Me)Phe4-Gly5-ol/enkephalin (DAGO). From our data it is evident that the opioid receptor subtypes are already present in the amphibian brain but the differences among them are less pronounced than in mammalian brain.« less

Model-based analyses reveal insular population diversification and cryptic frog species in the Ischnocnema parva complex in the Atlantic forest of Brazil.

PubMed

Gehara, Marcelo; Barth, Adriane; Oliveira, Eliana Faria de; Costa, Marco Antonio; Haddad, Célio Fernando Baptista; Vences, Miguel

2017-07-01

The Atlantic Forest (AF) of Brazil has long been recognized as a biodiversity conservation hotspot. Despite decades of studies the species inventory of this biome continues to increase with the discovery of cryptic diversity and the description of new species. Different diversification mechanisms have been proposed to explain the diversity in the region, including models of forest dynamics, barriers to gene flow and dispersal. Also, sea level change is thought to have influenced coastal diversification and isolated populations on continental islands. However, the timing and mode of diversification of insular populations in the AF region were rarely investigated. Here, we analyze the phylogeography and species diversity of the small-sized direct-developing frog Ischnocnema parva. These frogs are independent from water bodies but dependent on forest cover and high humidity, and provide good models to understand forest dynamics and insular diversification. Our analysis was based on DNA sequences for one mitochondrial and four nuclear genes of 71 samples from 18 localities including two islands, São Sebastião, municipality of Ilhabela, and Mar Virado, municipality of Ubatuba, both in the state of São Paulo. We use molecular taxonomic methods to show that I. parva is composed of six independently evolving lineages, with the nominal I. parva likely endemic to the type locality. The time-calibrated species tree shows that these lineages have diverged in the Pliocene and Pleistocene, suggesting the persistence of micro-refuges of forest in the AF. For the two insular populations we used approximate Bayesian computation to test different diversification hypotheses. Our findings support isolation with migration for São Sebastião population, with ∼1Mya divergence time, and isolation without migration for Mar Virado population, with ∼13Kya divergence time, suggesting a combination of different processes for diversification on AF islands. Copyright © 2017. Published by Elsevier Inc.

Widespread legacy brine contamination from oil production reduces survival of chorus frog larvae

USGS Publications Warehouse

Hossack, Blake R.; Puglis, Holly J.; Battaglin, William A.; Anderson, Chauncey; Honeycutt, Richard; Smalling, Kelly

2017-01-01

Advances in drilling techniques have facilitated a rapid increase in hydrocarbon extraction from energy shales, including the Williston Basin in central North America. This area overlaps with the Prairie Pothole Region, a region densely populated with wetlands that provide numerous ecosystem services. Historical (legacy) disposal practices often released saline co-produced waters (brines) with high chloride concentrations, affecting wetland water quality directly or persisting in sediments. Despite the potential threat of brine contamination to aquatic habitats, there has been little research into its ecological effects. We capitalized on a gradient of legacy brine-contaminated wetlands in northeast Montana to conduct laboratory experiments to assess variation in survival of larval Boreal Chorus Frogs (Pseudacris maculata) reared on sediments from 3 local wetlands and a control source. To help provide environmental context for the experiment, we also measured chloride concentrations in 6 brine-contaminated wetlands in our study area, including the 2 contaminated sites used for sediment exposures. Survival of frog larvae during 46- and 55-day experiments differed by up to 88% among sediment sources (Site Model) and was negatively correlated with potential chloride exposure (Chloride Model). Five of the 6 contaminated wetlands exceeded the U.S. EPA acute benchmark for chloride in freshwater (860 mg/L) and all exceeded the chronic benchmark (230 mg/L). However, the Wetland Site model explained more variation in survival than the Chloride Model, suggesting that chloride concentration alone does not fully reflect the threat of contamination to aquatic species. Because the profiles of brine-contaminated sediments are complex, further surveys and experiments are needed across a broad range of conditions, especially where restoration or remediation actions have reduced brine-contamination. Information provided by this study can help quantify potential ecological threats and help land managers prioritize conservation strategies as part of responsible and sustainable energy development.

They're a Hard Act to Follow: Four Professors Who Make Them Laugh in Liberal Arts.

ERIC Educational Resources Information Center

Blue, Thomas R.; And Others

Four teachers at Fort Lewis College, Colorado, use humor to send messages which "leap frog" resistance to the new and different, and go directly to the preconscious. The power in these humorous conceptual leaps is that the entering information sticks to the anger and passions of the human psyche, thus fostering retention. Linda Mack, a…

Paced Reading in Semantic Dementia: Word Knowledge Contributes to Phoneme Binding in Rapid Speech Production

ERIC Educational Resources Information Center

Jefferies, Elizabeth; Grogan, John; Mapelli, Cristina; Isella, Valeria

2012-01-01

Patients with semantic dementia (SD) show deficits in phoneme binding in immediate serial recall: when attempting to reproduce a sequence of words that they no longer fully understand, they show frequent migrations of phonemes between items (e.g., cap, frog recalled as "frap, cog"). This suggests that verbal short-term memory emerges directly from…

Breeding chorus indices are weakly related to estimated abundance of boreal chorus frogs

Treesearch

Paul Stephen Corn; Erin Muths; Amanda M. Kissel; Rick D. Scherer

2011-01-01

Call surveys used to monitor breeding choruses of anuran amphibians generate index values that are frequently used to represent the number of male frogs present, but few studies have quantified this relationship. We compared abundance of male Boreal Chorus Frogs (Pseudacris maculata), estimated using capture-recapture methods in two populations in Colorado, to call...

Surveys for California red-legged frog and arroyo toad on the Los Padres National Forest

Treesearch

Valerie K. Hubbartt; Thomas G. Murphey

2005-01-01

Starting in the spring of 1999 through the fall of 2000, USDA Forest Service biologists have conducted surveys throughout the Los Padres National Forest for the federally-listed California red-legged frog (Rana aurora draytonii) and arroyo toad (Bufo californicus). Sites known to have frogs or toads present were monitored for...

Conduction velocity of action potentials measured from unidimensional latency-topography in human and frog skeletal muscle fibers.

PubMed

Homma, S; Nakajima, Y; Hayashi, K; Toma, S

1986-01-01

Conduction of an action potential along skeletal muscle fibers was graphically displayed by unidimensional latency-topography, UDLT. Since the slopes of the equipotential line were linear and the width of the line was constant, it was possible to calculate conduction velocity from the slope. To determine conduction direction of the muscle action potential elicited by electric stimulation applied directly to the muscle, surface recording electrodes were placed on a two-dimensional plane over a human muscle. Thus a bi-dimensional topography was obtained. Then, twelve or sixteen surface electrodes were placed linearly along the longitudinal direction of the action potential conduction which was disclosed by the bi-dimensional topography. Thus conduction velocity of muscle action potential in man, calculated from the slope, was for m. brachioradialis, 3.9 +/- 0.4 m/s; for m. biceps brachii, 3.6 +/- 0.2 m/s; for m. sternocleidomastoideus, 3.6 +/- 0.4 m/s. By using a tungsten microelectrode to stimulate the motor axons, a convex-like equipotential line of an action potential in UDLT was obtained from human muscle fibers. Since a similar pattern of UDLT was obtained from experiments on isolated frog muscles, in which the muscle action potential was elicited by stimulating the motor axon, it was assumed that the maximum of the curve corresponds to the end-plate region, and that the slopes on both sides indicate bi-directional conduction of the action potential.

Biodiversity of frog haemoparasites from sub-tropical northern KwaZulu-Natal, South Africa

PubMed Central

Netherlands, Edward C.; Cook, Courtney A.; Kruger, Donnavan J.D.; du Preez, Louis H.; Smit, Nico J.

2015-01-01

Since South Africa boasts a high biodiversity of frog species, a multispecies haemoparasite survey was conducted by screening the blood from 29 species and 436 individual frogs. Frogs were collected at three localities in sub-tropical KwaZulu-Natal, a hotspot for frog diversity. Twenty per cent of the frogs were infected with at least one of five groups of parasites recorded. Intraerythrocytic parasites comprising Hepatozoon, Dactylosoma, and viral or bacterial organisms, as well as extracellular parasites including trypanosomes and microfilarid nematodes were found. A significant difference (P < 0.01) in the prevalence of parasitaemia was found across species, those semi-aquatic species demonstrating the highest, followed by semi-terrestrial frog species. None of those species described as purely terrestrial and aquatic were infected. Hepatozoon and Trypanosoma species accounted for most of the infections, the former demonstrating significant differences in intensity of infection across species, families and habitat types (P = 0.028; P = 0.006; P = 0.007 respectively). Per locality, the first, the formally protected Ndumo Game Reserve, had the highest biodiversity of haemoparasite infections, with all five groups of parasites recorded. The other two sites, that is the area bordering the reserve and the Kwa Nyamazane Conservancy, had a lower diversity with no parasite infections recorded and only Hepatozoon species recorded respectively. Such findings could be ascribed to the anthropogenic impact on the latter two sites, the first by the rural village activities, and the second by the bordering commercial sugar cane agriculture. Future studies should include both morphological and molecular descriptions of the above parasites, as well as the identification of potential vectors, possibly clarifying the effects human activities may have on frog haemoparasite life cycles and as such their biodiversity. PMID:25830113

Differential uptake of gold nanoparticles by 2 species of tadpole, the wood frog (Lithobates sylvaticus) and the bullfrog (Lithobates catesbeianus).

PubMed

Thompson, Lucas B; Carfagno, Gerardo L F; Andresen, Kurt; Sitton, Andrea J; Bury, Taylor; Lee, Laura L; Lerner, Kevin T; Fong, Peter P

2017-12-01

Engineered nanoparticles are aquatic contaminants of emerging concern that exert ecotoxicological effects on a wide variety of organisms. We exposed cetyltrimethylammonium bromide-capped spherical gold nanoparticles to wood frog and bullfrog tadpoles with conspecifics and in combination with the other species continuously for 21 d, then measured uptake and localization of gold. Wood frog tadpoles alone and in combination with bullfrog tadpoles took up significantly more gold than bullfrogs. Bullfrog tadpoles in combination with wood frogs took up significantly more gold than controls. The rank order of weight-normalized gold uptake was wood frogs in combination > wood frogs alone > bullfrogs in combination > bullfrogs alone > controls. In all gold-exposed groups of tadpoles, gold was concentrated in the anterior region compared with the posterior region of the body. The concentration of gold nanoparticles in the anterior region of wood frogs both alone and in combination with bullfrogs was significantly higher than the corresponding posterior regions. We also measured depuration time of gold in wood frogs. After 21 d in a solution of gold nanoparticles, tadpoles lost >83% of internalized gold when placed in gold-free water for 5 d. After 10 d in gold-free water, tadpoles lost 94% of their gold. After 15 d, gold concentrations were below the level of detection. Our finding of differential uptake between closely related species living in similar habitats with overlapping geographical distributions argues against generalizing toxicological effects of nanoparticles for a large group of organisms based on measurements in only one species. Environ Toxicol Chem 2017;36:3351-3358. © 2017 SETAC. © 2017 SETAC.

An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species.

PubMed

Dreher, Corinna E; Cummings, Molly E; Pröhl, Heike

2015-01-01

Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio) shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O. pumilio we selected four mainland populations and two island populations from Costa Rica and Panama. Spectrometric measurements of body coloration were used to calculate color and brightness contrasts of frogs as an indicator of conspicuousness for the visual systems of several potential predators (avian, crab and snake) and a conspecific observer. Additionally, we conducted experiments using clay model frogs of different coloration to investigate whether the local coloration of frogs is better protected than non-local color morphs, and if predator communities vary among populations. Overall predation risk differed strongly among populations and interestingly was higher on the two island populations. Imprints on clay models indicated that birds are the main predators while attacks of other predators were rare. Furthermore, clay models of local coloration were equally likely to be attacked as those of non-local coloration. Overall conspicuousness (and brightness contrast) of local frogs was positively correlated with attack rates by birds across populations. Together with results from earlier studies we conclude that conspicuousness honestly indicates toxicity to avian predators. The different coloration patterns among populations of strawberry poison frogs in combination with behavior and toxicity might integrate into equally efficient anti-predator strategies depending on local predation and other ecological factors.

An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species

PubMed Central

Dreher, Corinna E.; Cummings, Molly E.; Pröhl, Heike

2015-01-01

Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio) shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O. pumilio we selected four mainland populations and two island populations from Costa Rica and Panama. Spectrometric measurements of body coloration were used to calculate color and brightness contrasts of frogs as an indicator of conspicuousness for the visual systems of several potential predators (avian, crab and snake) and a conspecific observer. Additionally, we conducted experiments using clay model frogs of different coloration to investigate whether the local coloration of frogs is better protected than non-local color morphs, and if predator communities vary among populations. Overall predation risk differed strongly among populations and interestingly was higher on the two island populations. Imprints on clay models indicated that birds are the main predators while attacks of other predators were rare. Furthermore, clay models of local coloration were equally likely to be attacked as those of non-local coloration. Overall conspicuousness (and brightness contrast) of local frogs was positively correlated with attack rates by birds across populations. Together with results from earlier studies we conclude that conspicuousness honestly indicates toxicity to avian predators. The different coloration patterns among populations of strawberry poison frogs in combination with behavior and toxicity might integrate into equally efficient anti-predator strategies depending on local predation and other ecological factors. PMID:26110826

Convergent Substitutions in a Sodium Channel Suggest Multiple Origins of Toxin Resistance in Poison Frogs.

PubMed

Tarvin, Rebecca D; Santos, Juan C; O'Connell, Lauren A; Zakon, Harold H; Cannatella, David C

2016-04-01

Complex phenotypes typically have a correspondingly multifaceted genetic component. However, the genotype-phenotype association between chemical defense and resistance is often simple: genetic changes in the binding site of a toxin alter how it affects its target. Some toxic organisms, such as poison frogs (Anura: Dendrobatidae), have defensive alkaloids that disrupt the function of ion channels, proteins that are crucial for nerve and muscle activity. Using protein-docking models, we predict that three major classes of poison frog alkaloids (histrionicotoxins, pumiliotoxins, and batrachotoxins) bind to similar sites in the highly conserved inner pore of the muscle voltage-gated sodium channel, Nav1.4. We predict that poison frogs are somewhat resistant to these compounds because they have six types of amino acid replacements in the Nav1.4 inner pore that are absent in all other frogs except for a distantly related alkaloid-defended frog from Madagascar, Mantella aurantiaca. Protein-docking models and comparative phylogenetics support the role of these replacements in alkaloid resistance. Taking into account the four independent origins of chemical defense in Dendrobatidae, phylogenetic patterns of the amino acid replacements suggest that 1) alkaloid resistance in Nav1.4 evolved independently at least seven times in these frogs, 2) variation in resistance-conferring replacements is likely a result of differences in alkaloid exposure across species, and 3) functional constraint shapes the evolution of the Nav1.4 inner pore. Our study is the first to demonstrate the genetic basis of autoresistance in frogs with alkaloid defenses. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Biodiversity of frog haemoparasites from sub-tropical northern KwaZulu-Natal, South Africa.

PubMed

Netherlands, Edward C; Cook, Courtney A; Kruger, Donnavan J D; du Preez, Louis H; Smit, Nico J

2015-04-01

Since South Africa boasts a high biodiversity of frog species, a multispecies haemoparasite survey was conducted by screening the blood from 29 species and 436 individual frogs. Frogs were collected at three localities in sub-tropical KwaZulu-Natal, a hotspot for frog diversity. Twenty per cent of the frogs were infected with at least one of five groups of parasites recorded. Intraerythrocytic parasites comprising Hepatozoon, Dactylosoma, and viral or bacterial organisms, as well as extracellular parasites including trypanosomes and microfilarid nematodes were found. A significant difference (P < 0.01) in the prevalence of parasitaemia was found across species, those semi-aquatic species demonstrating the highest, followed by semi-terrestrial frog species. None of those species described as purely terrestrial and aquatic were infected. Hepatozoon and Trypanosoma species accounted for most of the infections, the former demonstrating significant differences in intensity of infection across species, families and habitat types (P = 0.028; P = 0.006; P = 0.007 respectively). Per locality, the first, the formally protected Ndumo Game Reserve, had the highest biodiversity of haemoparasite infections, with all five groups of parasites recorded. The other two sites, that is the area bordering the reserve and the Kwa Nyamazane Conservancy, had a lower diversity with no parasite infections recorded and only Hepatozoon species recorded respectively. Such findings could be ascribed to the anthropogenic impact on the latter two sites, the first by the rural village activities, and the second by the bordering commercial sugar cane agriculture. Future studies should include both morphological and molecular descriptions of the above parasites, as well as the identification of potential vectors, possibly clarifying the effects human activities may have on frog haemoparasite life cycles and as such their biodiversity.

INTRAOCULAR PRESSURE AND EXAMINATION FINDINGS IN THREE SPECIES OF CENTRAL AND SOUTH AMERICAN TREE FROGS (CRUZIOHYLA CRASPEDOPUS, CRUZIOHYLA CALCARIFER, AND ANOTHECA SPINOSA).

PubMed

Lewin, Andrew C; Hausmann, Jennifer C; Miller, Paul E

2017-09-01

The purpose of this prospective study was to describe intraocular pressure (IOP) and examination findings in three tree frog species (Cruziohyla craspedopus [fringe leaf frog], Cruziohyla calcarifer [splendid leaf frog], and Anotheca spinosa [spiny-headed or coronated tree frog]). Thirty-one C. craspedopus, four C. calcarifer, and five A. spinosa were weighed, sexed based on phenotype where possible, and examined using slit-lamp biomicroscopy and indirect ophthalmoscopy. IOP was measured using the TonoVet and TonoLab rebound tonometers while the frogs were held two ways (unrestrained, then restrained). Statistical differences were determined using one-way analysis of variance (ANOVA) and t-tests. Mean ± SD IOP (TonoVet and TonoLab, respectively) was 15.1 ± 2.5 mmHg and 15.6 ± 4.1 mmHg in C. craspedopus; 14.8 ± 1.5 mmHg and 18.8 ± 3.1 mmHg in C. calcarifer; and 9.1 ± 2.1 mmHg and 10.8 ± 1.4 mmHg in A. spinosa. There was no significant difference in IOP in C. craspedopus by eye (Right vs Left), tonometer, or restraint method. IOP in female C. craspedopus was 1-3 mm Hg higher than in males with both devices (P < 0.05). IOP was statistically significantly different between all species for the TonoLab and between Cruziohyla genus frogs and A. spinosa for the TonoVet (P < 0.05). There was no difference in IOP measurements between the TonoVet and TonoLab in C. craspedopus. IOP varied by gender in C. craspedopus and between species, but not by tonometer. Ocular abnormalities were minimal in this group of captive bred frogs.

Clinical signs, pathology and dose-dependent survival of adult wood frogs, Rana sylvatica, inoculated orally with frog virus 3 Ranavirus sp., Iridoviridae.

PubMed

Forzn, Mara J; Jones, Kathleen M; Vanderstichel, Raphal V; Wood, John; Kibenge, Frederick S B; Kuiken, Thijs; Wirth, Wytamma; Ariel, Ellen; Daoust, Pierre-Yves

2015-05-01

Amphibian populations suffer massive mortalities from infection with frog virus 3 FV3, genus Ranavirus, family Iridoviridae, a pathogen also involved in mortalities of fish and reptiles. Experimental oral infection with FV3 in captive-raised adult wood frogs, Rana sylvatica Lithobates sylvaticus, was performed as the first step in establishing a native North American animal model of ranaviral disease to study pathogenesis and host response. Oral dosing was successful LD50 was 10(2.93 2.423.44) p.f.u. for frogs averaging 35mm in length. Onset of clinical signs occurred 614days post-infection p.i. median 11 days p.i. and time to death was 1014 days p.i. median 12 days p.i.. Each tenfold increase in virus dose increased the odds of dying by 23-fold and accelerated onset of clinical signs and death by approximately 15. Ranavirus DNA was demonstrated in skin and liver of all frogs that died or were euthanized because of severe clinical signs. Shedding of virus occurred in faeces 710 days p.i. 34.5days before death and skin sheds 10 days p.i. 01.5days before death of some frogs dead from infection. Most common lesions were dermal erosion and haemorrhages haematopoietic necrosis in bone marrow, kidney, spleen and liver and necrosis in renal glomeruli, tongue, gastrointestinal tract and urinary bladder mucosa. Presence of ranavirus in lesions was confirmed by immunohistochemistry. Intracytoplasmic inclusion bodies probably viral were present in the bone marrow and the epithelia of the oral cavity, gastrointestinal tract, renal tubules and urinary bladder. Our work describes a ranaviruswood frog model and provides estimates that can be incorporated into ranavirus disease ecology models. © 2015 The Authors.

Anurans in a Subarctic Tundra Landscape Near Cape Churchill, Manitoba

USGS Publications Warehouse

Reiter, M.E.; Boal, C.W.; Andersen, D.E.

2008-01-01

Distribution, abundance, and habitat relationships of anurans inhabiting subarctic regions are poorly understood, and anuran monitoring protocols developed for temperate regions may not be applicable across large roadless areas of northern landscapes. In addition, arctic and subarctic regions of North America are predicted to experience changes in climate and, in some areas, are experiencing habitat alteration due to high rates of herbivory by breeding and migrating waterfowl. To better understand subarctic anuran abundance, distribution, and habitat associations, we conducted anuran calling surveys in the Cape Churchill region of Wapusk National Park, Manitoba, Canada, in 2004 and 2005. We conducted surveys along ~l-km transects distributed across three landscape types (coastal tundra, interior sedge meadow-tundra, and boreal forest-tundra interface) to estimate densities and probabilities of detection of Boreal Chorus Frogs (Pseudacris maculata) and Wood Frogs (Lithobates sylvaticus). We detected a Wood Frog or Boreal Chorus Frog on 22 (87%) of 26 transects surveyed, but probability of detection varied between years and species and among landscape types. Estimated densities of both species increased from the coastal zone inland toward the boreal forest edge. Our results suggest anurans occur across all three landscape types in our study area, but that species-specific spatial patterns exist in their abundances. Considerations for both spatial and temporal variation in abundance and detection probability need to be incorporated into surveys and monitoring programs for subarctic anurans.

Thyrotropin-Releasing Hormone (TRH) Promotes Wound Re-Epithelialisation in Frog and Human Skin

PubMed Central

Zhang, Guo-You; Emelianov, Vladimir; Paredes, Roberto; Debus, Sebastian; Augustin, Matthias; Funk, Wolfgang; Amaya, Enrique; Kloepper, Jennifer E.; Hardman, Matthew J.; Paus, Ralf

2013-01-01

There remains a critical need for new therapeutics that promote wound healing in patients suffering from chronic skin wounds. This is, in part, due to a shortage of simple, physiologically and clinically relevant test systems for investigating candidate agents. The skin of amphibians possesses a remarkable regenerative capacity, which remains insufficiently explored for clinical purposes. Combining comparative biology with a translational medicine approach, we report the development and application of a simple ex vivo frog (Xenopus tropicalis) skin organ culture system that permits exploration of the effects of amphibian skin-derived agents on re-epithelialisation in both frog and human skin. Using this amphibian model, we identify thyrotropin-releasing hormone (TRH) as a novel stimulant of epidermal regeneration. Moving to a complementary human ex vivo wounded skin assay, we demonstrate that the effects of TRH are conserved across the amphibian-mammalian divide: TRH stimulates wound closure and formation of neo-epidermis in organ-cultured human skin, accompanied by increased keratinocyte proliferation and wound healing-associated differentiation (cytokeratin 6 expression). Thus, TRH represents a novel, clinically relevant neuroendocrine wound repair promoter that deserves further exploration. These complementary frog and human skin ex vivo assays encourage a comparative biology approach in future wound healing research so as to facilitate the rapid identification and preclinical testing of novel, evolutionarily conserved, and clinically relevant wound healing promoters. PMID:24023889

Proposed method for evaluating the effects of PCBs in sediment on egg mass viability and reproductive success in frogs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt, C.S.; Henning, M.H.; Ebert, E.S.

1995-12-31

A proposed study design for evaluating the effect of PCBs in the sediments of a large New England river on reproductive success in frogs is described. Depending on field conditions and species abundance, the study will use either bullfrogs, Rana catesbiana; spring peepers, Hyla pickeringii; or green frogs, Rana claymitans as the study model. A selected number of gravid females will be collected from both the target area and a reference area matched with respect to a number of key variables including, but not limited to, stream flow, temperature, pH, substrate type, depth, surrounding land use, and organic carbon contentmore » of sediments. The gravid frogs will be transferred to a laboratory, where the egg masses will be stripped following induced ovulation, and then fertilized using semen from males collected in the field. Egg masses will be maintained under static renewal conditions for a period up to and including 7 days post hatch, during which mortality and gross morphological appearance will be evaluated. In the event that statistically significant differences in these endpoints are noted, a dose response model will be developed to relate observed effects to previously determined PCB concentrations in egg masses and maternal tissues. The results of this study will be of significant utility in evaluating reproductive toxicity of PCBs in ecological risk assessment.« less

Short-term occupancy and abundance dynamics of the Oregon spotted frog (Rana pretiosa) across its core range

USGS Publications Warehouse

Adams, Michael J.; Pearl, Christopher A.; Mccreary, Brome; Galvan, Stephanie

2014-01-01

The Oregon spotted frog (Rana pretiosa) occupies only a fraction of its original range and is listed as Threatened under the Endangered Species Act. We surveyed 93 sites in a rotating frame design (2010–13) in the Klamath and Deschutes Basins, Oregon, which encompass most of the species’ core extant range. Oregon spotted frogs are declining in abundance and probability of site occupancy. We did not find an association between the probability that Oregon spotted frogs disappear from a site (local extinction) and any of the variables hypothesized to affect Oregon spotted frog occupancy. This 4-year study provides baseline data, but the 4-year period was too short to draw firm conclusions. Further study is essential to understand how habitat changes and management practices relate to the status and trends of this species.

FROGS: Find, Rapidly, OTUs with Galaxy Solution.

PubMed

Escudié, Frédéric; Auer, Lucas; Bernard, Maria; Mariadassou, Mahendra; Cauquil, Laurent; Vidal, Katia; Maman, Sarah; Hernandez-Raquet, Guillermina; Combes, Sylvie; Pascal, Géraldine

2018-04-15

Metagenomics leads to major advances in microbial ecology and biologists need user friendly tools to analyze their data on their own. This Galaxy-supported pipeline, called FROGS, is designed to analyze large sets of amplicon sequences and produce abundance tables of Operational Taxonomic Units (OTUs) and their taxonomic affiliation. The clustering uses Swarm. The chimera removal uses VSEARCH, combined with original cross-sample validation. The taxonomic affiliation returns an innovative multi-affiliation output to highlight databases conflicts and uncertainties. Statistical results and numerous graphical illustrations are produced along the way to monitor the pipeline. FROGS was tested for the detection and quantification of OTUs on real and in silico datasets and proved to be rapid, robust and highly sensitive. It compares favorably with the widespread mothur, UPARSE and QIIME. Source code and instructions for installation: https://github.com/geraldinepascal/FROGS.git. A companion website: http://frogs.toulouse.inra.fr. geraldine.pascal@inra.fr. Supplementary data are available at Bioinformatics online.

Abundance of green tree frogs and insects in artificial canopy gaps in a bottomland hardwood forest.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horn, Scott; Hanula, James L.; Ulyshen, Michael D.

2005-01-01

Horn, Scott, James L. Hanula, Michael D. Ulyshen, and John C. Kilgo. 2005. Abundance of green tree frogs and insects in artificial canopy gaps in a bottomland hardwood forest. Am. Midl. Nat. 153:321-326. Abstract: We found more green tree frogs (Hyla cinerea) in canopy gaps than in closed canopy forest. Of the 331 green tree frogs observed, 88% were in canopy gaps. Likewise, higher numbers and biomasses of insects were captured in the open gap habitat. Flies were the most commonly collected insect group accounting for 54% of the total capture. These data suggest that one reason green tree frogsmore » were more abundant in canopy gaps was the increased availability of prey and that small canopy gaps provide early successional habitats that are beneficial to green tree frog populations.« less

Frog: The fast & realistic OpenGL event displayer

NASA Astrophysics Data System (ADS)

Quertenmont, Loïc

2010-04-01

FROG [1] [2] is a generic framework dedicated to visualisation of events in high energy physics experiment. It is suitable to any particular physics experiment or detector design. The code is light (< 3 MB) and fast (browsing time ~ 20 events per second for a large High Energy Physics experiment) and can run on various operating systems, as its object-oriented structure (C++) relies on the cross-platform OpenGL[3] and Glut [4] libraries. Moreover, Frog does not require installation of heavy third party libraries for the visualisation. This documents describes the features and principles of Frog version 1.106, its working scheme and numerous functionalities such as: 3D and 2D visualisation, graphical user interface, mouse interface, configuration files, production of pictures of various format, integration of personal objects, etc. Finally the application of FROG for physic experiment/environement, such as Gastof, CMS, ILD, Delphes will be presented for illustration.

From Clinging to Digging: The Postembryonic Skeletal Ontogeny of the Indian Purple Frog, Nasikabatrachus sahyadrensis (Anura: Nasikabatrachidae)

PubMed Central

Senevirathne, Gayani; Thomas, Ashish; Kerney, Ryan; Hanken, James; Biju, S. D.; Meegaskumbura, Madhava

2016-01-01

The Indian Purple frog, Nasikabatrachus sahyadrensis, occupies a basal phylogenetic position among neobatrachian anurans and has a very unusual life history. Tadpoles have a large ventral oral sucker, which they use to cling to rocks in torrents, whereas metamorphs possess adaptations for life underground. The developmental changes that underlie these shifts in habits and habitats, and especially the internal remodeling of the cranial and postcranial skeleton, are unknown. Using a nearly complete metamorphic series from free-living larva to metamorph, we describe the postembryonic skeletal ontogeny of this ancient and unique monotypic lineage. The torrent-dwelling larva possesses a dorsoventrally flattened body and a head with tiny dorsal eyes, robust lower and upper jaw cartilages, well-developed trabecular horns, and a definable gap between the trabecular horns and the tip of the snout. Unlike tadpoles of many other frogs, those of Nasikabatrachus retain larval mouthparts into late metamorphic stages. This unusual feature enables the larvae to maintain their clinging habit until near the end of metamorphosis. The subsequent ontogenetic shift from clinging to digging is correlated with rapid morphological changes and behavioral modifications. Metamorphs are equipped with a shortened tibiafibula and ossified prehallical elements, which likely facilitate initial digging using the hind limbs. Subsequently, the frogs may shift to headfirst burrowing by using the wedge-shaped skull, anteriorly positioned pectoral girdle, well-developed humeral crests and spatula-shaped forelimbs. The transition from an aquatic life in torrents to a terrestrial life underground entails dramatic changes in skeletal morphology and function that represent an extreme in metamorphic remodeling. Our analysis enhances the scope for detailed comparative studies across anurans, a group renowned for the diversity of its life history strategies. PMID:27028113

Susceptibility to disease varies with ontogeny and immunocompetence in a threatened amphibian.

PubMed

Abu Bakar, Amalina; Bower, Deborah S; Stockwell, Michelle P; Clulow, Simon; Clulow, John; Mahony, Michael J

2016-08-01

Ontogenetic changes in disease susceptibility have been demonstrated in many vertebrate taxa, as immature immune systems and limited prior exposure to pathogens can place less developed juveniles at a greater disease risk. By causing the disease chytridiomycosis, Batrachochytrium dendrobatidis (Bd) infection has led to the decline of many amphibian species. Despite increasing knowledge on how Bd varies in its effects among species, little is known on the interaction between susceptibility and development within host species. We compared the ontogenetic susceptibility of post-metamorphic green and golden bell frogs Litoria aurea to chytridiomycosis by simultaneously measuring three host-pathogen responses as indicators of the development of the fungus-infection load, survival rate, and host immunocompetence-following Bd exposure in three life stages (recently metamorphosed juveniles, subadults, adults) over 95 days. Frogs exposed to Bd as recently metamorphosed juveniles acquired higher infection loads and experienced lower immune function and lower survivorship than subadults and adults, indicating an ontogenetic decline in chytridiomycosis susceptibility. By corresponding with an intrinsic developmental maturation in immunocompetence seen in uninfected frogs, we suggest these developmental changes in host susceptibility in L. aurea may be immune mediated. Consequently, the physiological relationship between ontogeny and immunity may affect host population structure and demography through variation in life stage survival, and understanding this can shape management targets for effective amphibian conservation.

Potential for Loss of Breeding Habitat for Imperiled Mountain Yellow-legged Frog ( Rana muscosa) in High Sierra Nevada Mountain Water Bodies due to Reduced Snowpack: Interaction of Climate Change and an Introduced Predator

NASA Astrophysics Data System (ADS)

Lacan, I.; Matthews, K. R.

2005-12-01

Year to year variation in snowpack (20-200% average) and summer rain create large fluctuations in the volume of water in ponds and small lakes of the higher elevation (> 3000 m) Sierra Nevada. These water bodies are critical habitat for the imperiled mountain yellow-legged frog, Rana muscosa, which has decreased in abundance by 90% during the past century, due in part to the loss of suitable habitat and introduction of a fish predator (trout, Oncorhynchus spp.). Climate change is predicted to reduce the amount of snowpack, potentially impacting amphibian habitats throughout the Sierra Nevada by further reducing the lake and pond water levels and resulting in drying of small lakes during the summer. Mountain yellow-legged frogs are closely tied to water during all life stages, and are unique in having a three- to four-year tadpole phase. Thus, tadpole survival and future recruitment of adult frogs requires adequate water in lakes and ponds throughout the year, but larger lakes are populated with fish that prey on frogs and tadpoles. Thus, most successful frog breeding occurs in warm, shallow, fishless ponds that undergo wide fluctuations in volume. These water bodies would be most susceptible to the potential climate change effects of reduced snowpack, possibly resulting in lower tadpole survival. This study explores the link between the changes in water availability -- including complete pond drying -- and the abundance and recruitment of mountain yellow-legged frog in Dusy Basin, Kings Canyon National Park, California, USA. We propose using the low-snowpack years (1999, 2002, 2004) as comparative case studies to predict future effects of climate change on aquatic habitat availability and amphibian abundance and survival. To quantify the year to year variation and changes in water volume available to amphibians, we initiated GPS lake mapping in 2002 to quantify water volumes, water surface area, and shoreline length. We tracked these changes by repeated mapping of water surface and volume (bathymetry) during the summer, and concurrently counting all the life stages (adults, subadults, tadpoles) of frogs. As a baseline in this analysis, we present 2002 data when pond volume declined 40-100% during summer in three breeding lakes. The lakes that completely dried up in 2002 were repopulated by adults in 2003 but showed no recruitment of metamorphosed frogs from previous year's tadpoles. The lakes that retained water -- even if they underwent a large reduction in water volume (-60%), surface area (-70%) and shoreline length (-70%) during the summer -- show consistent tadpole-to-subadult recruitment in the following year (2003). Similar results are obtained using frog counts from 1999-2000 and 2004-2005 and estimates of water volume in those years. Our results suggest that more frequent summer drying of small ponds -- as may be induced by climate change -- will severely reduce frog recruitment. When combined with the invasive fish that prevent frog breeding in larger lakes, such effect of climate change may cause loss of local frog populations, and push the entire species towards extinction.

Effects of cadmium-enriched sediment on fish and amphibian embryo-larval stages

DOE Office of Scientific and Technical Information (OSTI.GOV)

Francis, P.C.; Birge, W.J.; Black, J.A.

1984-08-01

Aquatic toxicity tests were conducted to evaluate the effects of cadmium-enriched sediment on embryo-larval stages of the goldfish (Carassius auratus), leopard frog (Rana pipiens), and largemouth bass (Micropterus salmoides). Natural stream sediment was collected and enriched with cadmium to nominal concentrations of 1.0, 10.0, 100, and 1000 mg/kg. Enriched sediments were placed in Pyrex dishes and covered with 350 ml of reconstituted water. Fertilized eggs were placed in the dishes and maintained through 4 days posthatching, giving a total exposure time of 6 to 7 days. For all tests the cadmium concentrations ranged from 1.1 to 76.5 micrograms/liter in watermore » above sediments containing 1 to 1000 mg Cd/kg, respectively. Although low frequencies of mortality were observed in all tests, goldfish, leopard frog, and bass exposed to sediments enriched to 1000 mg Cd/kg accumulated 4.61, 12.55, and 60.0 micrograms Cd/g, respectively. No significant correlations were found between mortality of the goldfish and leopard frog and the cadmium concentrations in either water or sediment. However, all three species showed strong correlations between cadmium concentrations in water and tissue, sediment and tissue, and water and sediment. Tissue cadmium concentrations were related to the length of time test organisms were in direct contact with cadmium-enriched sediment.« less

Flow cytometry used to assess genetic damage in frogs from farm ponds

USGS Publications Warehouse

Bly, B.L.; Knutson, M.G.; Sandheinrich, M.B.; Gray, B.R.; Jobe, D.A.

2004-01-01

Flow cytometry (FC) is a laboratory method used to detect genetic damage induced by environmental contaminants and other stressors in animals, including amphibians. We tested FC methods on three species of ranid frogs collected from farm ponds and natural wetlands in southeastern Minnesota. We compared FC metrics for Rana clamitans between ponds with direct exposure to agricultural contaminants and reference (unexposed) ponds. Concentrations of atrazine in water from our farm ponds ranged from 0.04 to 0.55 ppb. We found that R. clamitans from exposed ponds had DNA content similar to frogs from unexposed ponds. Pond-averaged C-values (a measure of DNA content) ranged from 6.53 to 7.08 for R. pipiens (n . 13), 6.55 to 6.60 for R. clamitans (n . 40) and 6.74 for R. palustris (n . 5). Among all species, the mean sample CVs ranged from 1.91 (R. palustris) to 6.31 (R. pipiens). Deformities were observed in only 2 of 796 individuals among all species and occurred in both reference and exposed ponds. Although we did not detect evidence of DNA damage associated with agriculture in our study, we demonstrated the potential of FC for screening amphibian populations for genetic damage. Metrics from a variety of amphibian species and locations as well as laboratory studies are needed to further assess the value of FC for monitoring amphibian genetic integrity in contaminated sites.

Chiricahua leopard frog status in the Galiuro Mountains, Arizona, with a monitoring framework for the species' entire range

Treesearch

Lawrence L. C. Jones; Michael J. Sredl

2005-01-01

The Chiricahua leopard frog (Rana chiricahuensis) was historically widespread in suitable habitat throughout its range. Reports of recent population declines led to inventories of Chiricahua leopard frog localities. Surveys reported here establish a new baseline of occurrence in the Galiuros: only two of 21 historical localities were found to be...

Rangewide phylogeography of the western U.S. endemic frog Rana boylii (Ranidae): Implications for the conservation of frogs and rivers

Treesearch

A.J. Lind; H.B. Shaffer; P.Q. Spinks; G.M. Fellers

2011-01-01

Genetic data are increasingly being used in conservation planning for declining species. We sampled both the ecological and distributional limits of the foothill yellow-legged frog, Rana boylii to characterize mitochondrial DNA (mtDNA) variation in this declining, riverine amphibian. We evaluated 1525 base pairs (bp) of cytochrome b...

TaFROG encodes a Pooideae orphan protein that interacts with SnRK1 and enhances resistance to the mycotoxigenic fungus fusarium graminearum.

USDA-ARS?s Scientific Manuscript database

All genomes encode taxonomically restricted ‘orphan’ genes, most of which are of unknown function. We report the functional characterization of the orphan gene TaFROG as a component of the wheat resistance to the globally important Fusarium head blight (FHB) disease. TaFROG is taxonomically restrict...

Four new species of frogs and one new species of snake from the Chapare region of Bolivia, with notes on other species

USGS Publications Warehouse

Reynolds, R.P.; Foster, M.S.

1992-01-01

We report on a collection of 74 frogs, 11 lots of frog eggs or tadpoles, and two snakes collected from the Chapare Region in the yungas of the eastern Andean Cordillera de Cochabamba, Bolivia. Collecting localities range from approximately 300 m to >3200 m in elevation. The specimens pertain to 23 species, probably 10 of which are undescribed. We describe four new species of frogs, one each in the genera Bufo, Centrolenella, Colostethus, and Hyla, and one new species of snake, genus Dipsas. We place Atelopus rugulosus in synonymy with A. tricolor.

A novel reproductive mode in frogs: a new species of fanged frog with internal fertilization and birth of tadpoles.

PubMed

Iskandar, Djoko T; Evans, Ben J; McGuire, Jimmy A

2014-01-01

We describe a new species of fanged frog (Limnonectes larvaepartus) that is unique among anurans in having both internal fertilization and birth of tadpoles. The new species is endemic to Sulawesi Island, Indonesia. This is the fourth valid species of Limnonectes described from Sulawesi despite that the radiation includes at least 15 species and possibly many more. Fewer than a dozen of the 6455 species of frogs in the world are known to have internal fertilization, and of these, all but the new species either deposit fertilized eggs or give birth to froglets.

Jan Swammerdam's frogs

PubMed Central

Sleigh, Charlotte

2012-01-01

Having discussed insect metamorphosis at length, Jan Swammerdam's Bybel der Natuure (1679/1737) reached its climax with a substantial description of the generation and muscular activity of frogs. This paper explores the rhetorical role of frogs in Swammerdam's ‘great work’, showing how they were the Archimedean point from which he aimed to reorder all of creation—from insects to humans—within one glorious, God-ordained natural history and philosophy. Swammerdam linked insects to frogs through a demonstration that all underwent epigenesis; and frogs were then linked to humans through a demonstration of their identical muscular activity. The success of Swammerdam's strategy required a theological reconstruction of the frog, traditionally an ungodly creature, such that trustworthy knowledge could be obtained from its body. Perhaps surprisingly, this act of theological cleansing is shown to be somewhat prefigured in the distinctly non-experimental natural history of Edward Topsell (1608). The paper also examines Swammerdam's interactions with the mystic Antoinette Bourignon, and his challenges in reconciling a spirituality of meletetics with a material epistemology in natural philosophy. Differences are revealed between the natural analogies given by Swammerdam in his published and unpublished writings, undermining to a certain extent the triumphal insect–frog–human rhetorical structure of the Bybel.

Odorous and Non-Fatal Skin Secretion of Adult Wrinkled Frog (Rana rugosa) Is Effective in Avoiding Predation by Snakes

PubMed Central

Yoshimura, Yuri; Kasuya, Eiiti

2013-01-01

The roles played by nonfatal secretions of adult anurans in the avoidance of predation remain unknown. The adult Wrinkled frog (Rana rugosa) has warty skin with the odorous mucus secretion that is not fatal to the snake Elaphe quadrivirgata. We fed R. rugosa or Fejervarya limnocharis, which resembles R. rugosa in appearance and has mucus secretion, to snakes and compared the snakes’ responses to the frogs. Compared to F. limnocharis, R. rugosa was less frequently bitten or swallowed by snakes. The snakes that bit R. rugosa spat out the frogs and showed mouth opening (gaping) behavior, while the snakes that bit F. limnocharis did not show gaping behavior. We also compared the responses of the snakes to R. rugosa and F. limnocharis secretions. We coated palatable R. japonica with secretions from R. rugosa or F. limnocharis. The frogs coated by R. rugosa secretion were less frequently bitten or swallowed than those coated by F. limnocharis secretion. We concluded that compared to different frog species of similar sizes, the adult R. rugosa was less frequently preyed upon by, and that its skin secretion was effective in avoiding predation by snakes. PMID:24278410

Chemical camouflage--a frog's strategy to co-exist with aggressive ants.

PubMed

Rödel, Mark-Oliver; Brede, Christian; Hirschfeld, Mareike; Schmitt, Thomas; Favreau, Philippe; Stöcklin, Reto; Wunder, Cora; Mebs, Dietrich

2013-01-01

Whereas interspecific associations receive considerable attention in evolutionary, behavioural and ecological literature, the proximate bases for these associations are usually unknown. This in particular applies to associations between vertebrates with invertebrates. The West-African savanna frog Phrynomantis microps lives in the underground nest of ponerine ants (Paltothyreus tarsatus). The ants usually react highly aggressively when disturbed by fiercely stinging, but the frog is not attacked and lives unharmed among the ants. Herein we examined the proximate mechanisms for this unusual association. Experiments with termites and mealworms covered with the skin secretion of the frog revealed that specific chemical compounds seem to prevent the ants from stinging. By HPLC-fractionation of an aqueous solution of the frogs' skin secretion, two peptides of 1,029 and 1,143 Da were isolated and found to inhibit the aggressive behaviour of the ants. By de novo sequencing using tandem mass spectrometry, the amino acid sequence of both peptides consisting of a chain of 9 and 11 residues, respectively, was elucidated. Both peptides were synthesized and tested, and exhibited the same inhibitory properties as the original frog secretions. These novel peptides most likely act as an appeasement allomone and may serve as models for taming insect aggression.

Urea loading enhances freezing survival and postfreeze recovery in a terrestrially hibernating frog.

PubMed

Costanzo, Jon P; Lee, Richard E

2008-09-01

We tested the hypothesis that urea, an osmolyte accumulated early in hibernation, functions as a cryoprotectant in the freeze-tolerant wood frog, Rana sylvatica. Relative to saline-treated, normouremic (10 micromol ml(-1)) frogs, individuals rendered hyperuremic (70 micromol ml(-1)) by administration of an aqueous urea solution exhibited significantly higher survival (100% versus 64%) following freezing at -4 degrees C, a potentially lethal temperature. Hyperuremic frogs also had lower plasma levels of intracellular proteins (lactate dehydrogenase, creatine kinase, hemoglobin), which presumably escaped from damaged cells, and more quickly recovered neurobehavioral functions following thawing. Experimental freezing-thawing did not alter tissue urea concentrations, but did elevate glucose levels in the blood and organs of all frogs. When measured 24 h after thawing commenced, glucose concentrations were markedly higher in urea-loaded frogs as compared to saline-treated ones, possibly because elevated urea retarded glucose clearance. Like other low-molecular-mass cryoprotectants, urea colligatively reduces both the amount of ice forming within the body and the osmotic dehydration of cells. In addition, by virtue of certain non-colligative properties, it may bestow additional protection from freeze-thaw damage not afforded by glucose.

Odorous and non-fatal skin secretion of adult wrinkled frog (Rana rugosa) is effective in avoiding predation by snakes.

PubMed

Yoshimura, Yuri; Kasuya, Eiiti

2013-01-01

The roles played by nonfatal secretions of adult anurans in the avoidance of predation remain unknown. The adult Wrinkled frog (Rana rugosa) has warty skin with the odorous mucus secretion that is not fatal to the snake Elaphe quadrivirgata. We fed R. rugosa or Fejervarya limnocharis, which resembles R. rugosa in appearance and has mucus secretion, to snakes and compared the snakes' responses to the frogs. Compared to F. limnocharis, R. rugosa was less frequently bitten or swallowed by snakes. The snakes that bit R. rugosa spat out the frogs and showed mouth opening (gaping) behavior, while the snakes that bit F. limnocharis did not show gaping behavior. We also compared the responses of the snakes to R. rugosa and F. limnocharis secretions. We coated palatable R. japonica with secretions from R. rugosa or F. limnocharis. The frogs coated by R. rugosa secretion were less frequently bitten or swallowed than those coated by F. limnocharis secretion. We concluded that compared to different frog species of similar sizes, the adult R. rugosa was less frequently preyed upon by, and that its skin secretion was effective in avoiding predation by snakes.

California red-legged frog (Rana draytonii) movement and habitat use: Implications for conservation

USGS Publications Warehouse

Fellers, G.M.; Kleeman, P.M.

2007-01-01

Nonbreeding habitats are critically important for Rana draytonii, especially for individuals that breed in temporary bodies of water. We radiotracked 123 frogs to evaluate seasonal habitat use. Individual frogs were continuously tracked for up to 16 months. Some individuals remained at breeding ponds all year, but 66% of female and 25% of male frogs moved to nonbreeding areas, even when the breeding site retained water. Frogs at our main study site moved 150 m (median), roughly the distance to the nearest suitable nonbreeding area. The greatest straight-line distance traveled was 1.4 km, although the presumed distance traveled was 2.8 km. Females were more likely than males to move from permanent ponds (38% of females, 16% of males), but among dispersing frogs, males and females did not differ in distance moved. Some frogs left breeding sites shortly after oviposition (median = 12 days for females, 42.5 days for males), but many individuals remained until the site was nearly dry. Fog provided moisture for dispersal or migration throughout the summer. Our data demonstrate that maintaining populations of pond-breeding amphibians requires that all essential habitat components be protected; these include (1) breeding habitat, (2) nonbreeding habitat, and (3) migration corridors. In addition, a buffer is needed around all three areas to ensure that outside activities do not degrade any of the three habitat components. Copyright 2007 Society for the Study of Amphibians and Reptiles.

Effects of gravity on ontogeny in animals.

NASA Technical Reports Server (NTRS)

Pitts, G. C.

1973-01-01

Inversion or clinostat rotation of frogs' eggs demonstrated a critical period of enhanced gravity-sensitivity prior to the first cleavage. These results were corroborated by centrifugation studies which localized the period of maximal sensitivity at approximately 20 minutes post-fertilization. Eggs of various invertebrates suspended in aqueous solution proved capable of normal development following brief ultracentrifugation. Among fly larvae, grasshopper nymphs, turtles, mice, rats, and chickens, growth rates were inversely related to G-force, and maximal chronic acceleration tolerated was inversely related to body size. Body composition data demonstrated the importance of separately evaluating fat and the fat-free portion of the body in studies of the effect of acceleration on growth in homeotherms. The attempt to evaluate the effect of weightlessness on the development of frogs' eggs in Biosatellite 2 was inconclusive for technical reasons.

Estimating Effects of Species Interactions on Populations of Endangered Species.

PubMed

Roth, Tobias; Bühler, Christoph; Amrhein, Valentin

2016-04-01

Global change causes community composition to change considerably through time, with ever-new combinations of interacting species. To study the consequences of newly established species interactions, one available source of data could be observational surveys from biodiversity monitoring. However, approaches using observational data would need to account for niche differences between species and for imperfect detection of individuals. To estimate population sizes of interacting species, we extended N-mixture models that were developed to estimate true population sizes in single species. Simulations revealed that our model is able to disentangle direct effects of dominant on subordinate species from indirect effects of dominant species on detection probability of subordinate species. For illustration, we applied our model to data from a Swiss amphibian monitoring program and showed that sizes of expanding water frog populations were negatively related to population sizes of endangered yellow-bellied toads and common midwife toads and partly of natterjack toads. Unlike other studies that analyzed presence and absence of species, our model suggests that the spread of water frogs in Central Europe is one of the reasons for the decline of endangered toad species. Thus, studying population impacts of dominant species on population sizes of endangered species using data from biodiversity monitoring programs should help to inform conservation policy and to decide whether competing species should be subject to population management.

Temperature variation, bacterial diversity and fungal infection dynamics in the amphibian skin.

PubMed

Longo, Ana V; Zamudio, Kelly R

2017-09-01

Host-associated bacterial communities on the skin act as the first line of defence against invading pathogens. Yet, for most natural systems, we lack a clear understanding of how temperature variability affects structure and composition of skin bacterial communities and, in turn, promotes or limits the colonization of opportunistic pathogens. Here, we examine how natural temperature fluctuations might be related to changes in skin bacterial diversity over time in three amphibian populations infected by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). Our focal host species (Eleutherodactylus coqui) is a direct-developing frog that has suffered declines at some populations in the last 20 years, while others have not experienced any changes. We quantified skin bacterial alpha- and beta-diversity at four sampling time points, a period encompassing two seasons and ample variation in natural infections and environmental conditions. Despite the different patterns of infection across populations, we detected an overall increase in bacterial diversity through time, characterized by the replacement of bacterial operational taxonomic units (OTUs). Increased frog body temperatures possibly allowed the colonization of bacteria as well as the recruitment of a subset of indicator OTUs, which could have promoted the observed changes in diversity patterns. Our results suggest that natural environmental fluctuations might be involved in creating opportunities for bacterial replacement, potentially attenuating pathogen transmission and thus contributing to host persistence in E. coqui populations. © 2017 John Wiley & Sons Ltd.

ON THE RELATION OF DIRECT CURRENTS TO CONDENSER DISCHARGES AS STIMULI

PubMed Central

Blair, H. A.

1935-01-01

Data on the electrical stimulation of sciatic-gastrocnemius preparations of the frog by both direct currents and condenser discharges at the same time are discussed in relation to the validity of the differential equation See PDF for Equation where p is the local excitatory process, V the stimulating current or voltage, and K and k are constants. It is concluded that the constant k is the same whether it is derived from the data of the one stimulus or the other when the same fibres are being stimulated. PMID:19872885

Testing the effect of dietary carotenoids on larval survival, growth and development in the critically endangered southern corroboree frog.

PubMed

Byrne, Phillip G; Silla, Aimee J

2017-03-01

The success of captive breeding programs (CBPs) for threatened species is often limited due to a lack of knowledge of the nutritional conditions required for optimal growth and survival. Carotenoids are powerful antioxidants known to accelerate vertebrate growth and reduce mortality. However, the effect of carotenoids on amphibian life-history traits remains poorly understood. The aim of our study was to use a manipulative laboratory experiment to test the effect of dietary-carotenoid supplementation during the larval life stage on the survival, growth and development of the critically endangered southern corroboree frog (Pseudophryne corroboree). Larvae were fed either a carotenoid supplemented diet or an unsupplemented diet and the survival, growth and development of individuals was monitored and compared. There was no significant effect of dietary treatment on larval survival, growth rate, time taken to reach metamorphosis, or body size at metamorphosis. Our findings provide no evidence that carotenoid supplementation during the larval life stage improves the growth and development of southern corroboree frogs. However, because the carotenoid dose used in our study did not have any detrimental effects on P. corroboree larvae, but has previously been shown to improve adult coloration, immunity, and exercise performance, carotenoid supplementation should be considered when evaluating the nutritional requirements of P. corroboree in captivity. Carotenoid supplementation studies are now required for a diversity of anuran species to determine the effects of carotenoids on amphibian survival, growth and development. Understanding the effects of dietary carotenoids on different life-history traits may assist with amphibian captive breeding and conservation. © 2017 Wiley Periodicals, Inc.

How spatio-temporal habitat connectivity affects amphibian genetic structure

PubMed Central

Watts, Alexander G.; Schlichting, Peter E.; Billerman, Shawn M.; Jesmer, Brett R.; Micheletti, Steven; Fortin, Marie-Josée; Funk, W. Chris; Hapeman, Paul; Muths, Erin; Murphy, Melanie A.

2015-01-01

Heterogeneous landscapes and fluctuating environmental conditions can affect species dispersal, population genetics, and genetic structure, yet understanding how biotic and abiotic factors affect population dynamics in a fluctuating environment is critical for species management. We evaluated how spatio-temporal habitat connectivity influences dispersal and genetic structure in a population of boreal chorus frogs (Pseudacris maculata) using a landscape genetics approach. We developed gravity models to assess the contribution of various factors to the observed genetic distance as a measure of functional connectivity. We selected (a) wetland (within-site) and (b) landscape matrix (between-site) characteristics; and (c) wetland connectivity metrics using a unique methodology. Specifically, we developed three networks that quantify wetland connectivity based on: (i) P. maculata dispersal ability, (ii) temporal variation in wetland quality, and (iii) contribution of wetland stepping-stones to frog dispersal. We examined 18 wetlands in Colorado, and quantified 12 microsatellite loci from 322 individual frogs. We found that genetic connectivity was related to topographic complexity, within- and between-wetland differences in moisture, and wetland functional connectivity as contributed by stepping-stone wetlands. Our results highlight the role that dynamic environmental factors have on dispersal-limited species and illustrate how complex asynchronous interactions contribute to the structure of spatially-explicit metapopulations. PMID:26442094

Composition of symbiotic bacteria predicts survival in Panamanian golden frogs infected with a lethal fungus

PubMed Central

Becker, Matthew H.; Walke, Jenifer B.; Cikanek, Shawna; Savage, Anna E.; Mattheus, Nichole; Santiago, Celina N.; Minbiole, Kevin P. C.; Harris, Reid N.; Belden, Lisa K.; Gratwicke, Brian

2015-01-01

Symbiotic microbes can dramatically impact host health and fitness, and recent research in a diversity of systems suggests that different symbiont community structures may result in distinct outcomes for the host. In amphibians, some symbiotic skin bacteria produce metabolites that inhibit the growth of Batrachochytrium dendrobatidis (Bd), a cutaneous fungal pathogen that has caused many amphibian population declines and extinctions. Treatment with beneficial bacteria (probiotics) prevents Bd infection in some amphibian species and creates optimism for conservation of species that are highly susceptible to chytridiomycosis, the disease caused by Bd. In a laboratory experiment, we used Bd-inhibitory bacteria from Bd-tolerant Panamanian amphibians in a probiotic development trial with Panamanian golden frogs, Atelopus zeteki, a species currently surviving only in captive assurance colonies. Approximately 30% of infected golden frogs survived Bd exposure by either clearing infection or maintaining low Bd loads, but this was not associated with probiotic treatment. Survival was instead related to initial composition of the skin bacterial community and metabolites present on the skin. These results suggest a strong link between the structure of these symbiotic microbial communities and amphibian host health in the face of Bd exposure and also suggest a new approach for developing amphibian probiotics. PMID:25788591

How spatio-temporal habitat connectivity affects amphibian genetic structure

USGS Publications Warehouse

Watts, Alexander G.; Schlichting, P; Billerman, S; Jesmer, B; Micheletti, S; Fortin, M.-J.; Funk, W.C.; Hapeman, P; Muths, Erin L.; Murphy, M.A.

2015-01-01

Heterogeneous landscapes and fluctuating environmental conditions can affect species dispersal, population genetics, and genetic structure, yet understanding how biotic and abiotic factors affect population dynamics in a fluctuating environment is critical for species management. We evaluated how spatio-temporal habitat connectivity influences dispersal and genetic structure in a population of boreal chorus frogs (Pseudacris maculata) using a landscape genetics approach. We developed gravity models to assess the contribution of various factors to the observed genetic distance as a measure of functional connectivity. We selected (a) wetland (within-site) and (b) landscape matrix (between-site) characteristics; and (c) wetland connectivity metrics using a unique methodology. Specifically, we developed three networks that quantify wetland connectivity based on: (i) P. maculata dispersal ability, (ii) temporal variation in wetland quality, and (iii) contribution of wetland stepping-stones to frog dispersal. We examined 18 wetlands in Colorado, and quantified 12 microsatellite loci from 322 individual frogs. We found that genetic connectivity was related to topographic complexity, within- and between-wetland differences in moisture, and wetland functional connectivity as contributed by stepping-stone wetlands. Our results highlight the role that dynamic environmental factors have on dispersal-limited species and illustrate how complex asynchronous interactions contribute to the structure of spatially-explicit metapopulations.

Amphibian fertilization and development in microgravity

NASA Technical Reports Server (NTRS)

Souza, Kenneth A.

1993-01-01

During the year before launch, female frogs will be tested every 3 months for the quantity and quality of eggs produced. Two weeks or more prior to launch, male and female frogs will be transported to the John F. Kennedy Space Center (KSC). During the few weeks before launch, groups will be periodically tested for egg quality to assure that the frogs have adapted to the KSC laboratory environment. About 27 hours before launch, four females will be placed in a damp foam-lined box, called the Adult Frog Box (AFB), through which 100 cc/min of air wil be circulated. The AFB will be lowered into the Spacelab and loaded into the Frog Environmental Unit (FEU) during the final pre-launch preparations. A sperm suspension, for use in flight to fertilize the eggs, will also be prepared and loaded during the pre-launch period. The sperm suspension, together with a kit of syringes containing Human Chorionic Gonadotropin (HCG), will be stored in a refrigerator aboard the shuttle until needed in flight. On the first day of flight, the AFB will be transferred from the FEU to the General Purpose Work Station (GPWS), which is a type of glove box specially designed to allow the crew to use chemicals and biological materials during the flight without contaminating the shuttle/Spacelab environment. Inside the GPWS the four adult frogs will be injected with the HCG hormone and returned to the FEU. Approximately 16 hours after injection, ovulation should have taken place and 15 to 20 eggs from each frog will be placed on each of two egg baskets and covered with sperm for 10 minutes. The egg baskets are inserted into acrylic egg chambers and 50 ml of 'pond water' (20 percent strength Modified Ringers solution (is added. One of the chambers from each frog will be placed on a centrifuge within the FEU and rotated to simulate normal terrestrial gravity (1 g). The remaining chambers are incubated under microgravity conditions within the FEU. Forty minutes after fertilization, the four chambers exposed to 1 g will be removed and observed within the GPWS using a dissecting microscope and camera system. On the basis of egg rotation and egg appearance, the 'best' and 'second best' frogs will be selected to contribute additional eggs. Using the two best frogs, 22 egg chambers will be loaded with eggs and fertilized. Eleven chambers wil be incubated at microgravity and eleven will be incubated on the centrifuge. At various times during the flight, chambers will be removed from the FEU and transferred to the GPWS where a formaldehyde-based fixative will be injected in order to preserve important developmental stages for in depth study following the flight. Five of the 22 chambers plus the eight fertilization test chambers will be returned to Earth with live tadpoles. The swimming behavior of these free swimming tadpoles will be examined within several hours of landing and some will be fixed for a detailed analysis of their inner ear, the otolity, the animals 'balance system.' Lychakov and Vinikov reported an increase in otolith size in tadpoles that developed (but were not fertilized) in space. Live tadpoles from the SL-J flight will be raised through metamorphsis for studies of maturation including an analysis of the effects of space flight on their ability to produce normal progency. Following the flight, the fixed embryos will be serially sectioned and stained using procedures that were developed for this experiment. The embroys fixed at the 2-4 cell stage will be examined for the distribution of cytoplasmic contents, including the various classes of yolk platelets, and the location and shape of the cleavage furrows. The gastrulae will be assessed for the normality of the complex cellular rearrangements that constitute blastopore formation and involution, i.e., the differentiation of the embryo into its specialized body parts. Using a new procedure, the gastrulae will be bleached which will enable the initial sperm entry point (SEP) to be located. The correlation between the SEP and the dorsal lip of the blastopore will be determined. Under normal terrestrial conditions it was shown that the SEP typically is located on the side of the egg opposite the future dorsal side of the embryo. The neurulae will be examined for the normality and completeness of the neural plate and archenteron expansion. The tadpole stages will be used to study the allometry and morphology of the various organ systems.

Abundance of green tree frogs and insects in artificial canopy gaps in a bottomland hardwood forest

Treesearch

Scott Horn; James L. Hanula; Michael D. Ulyshen; John C. Kilgo

2005-01-01

We found more green tree frogs (Hyla cinera) in canopy gaps than in closed canopy forest. Of the 331 gree ntree frogs observed, 88% were in canopy gaps. Likewise, higher numbers and biomasses of insects were captured in the open gap habitat. Flies were the most commonly collected insect group accounting for 54% of the total capture. These data...

Movement ecology and seasonal distribution of mountain yellow-legged frogs, Rana muscosa, in a high-elevation Sierra Nevada basin.

Treesearch

K.L. Pope; K.R. Matthews

2001-01-01

Movement ecology and seasonal distribution of mountain yellow-legged frogs (Rana muscosa) in Dusy Basin (3470 m), Kings Canyon National Park, California, were characterized using passive integrated transponder (PIT) surveys and visual encounter surveys. We individually PIT-tagged 500 frogs during the summers of 1997 and 1998 and monitored these individuals during seven...

Introducing the Forensic Research/Reference on Genetics knowledge base, FROG-kb

PubMed Central

2012-01-01

Background Online tools and databases based on multi-allelic short tandem repeat polymorphisms (STRPs) are actively used in forensic teaching, research, and investigations. The Fst value of each CODIS marker tends to be low across the populations of the world and most populations typically have all the common STRP alleles present diminishing the ability of these systems to discriminate ethnicity. Recently, considerable research is being conducted on single nucleotide polymorphisms (SNPs) to be considered for human identification and description. However, online tools and databases that can be used for forensic research and investigation are limited. Methods The back end DBMS (Database Management System) for FROG-kb is Oracle version 10. The front end is implemented with specific code using technologies such as Java, Java Servlet, JSP, JQuery, and GoogleCharts. Results We present an open access web application, FROG-kb (Forensic Research/Reference on Genetics-knowledge base, http://frog.med.yale.edu), that is useful for teaching and research relevant to forensics and can serve as a tool facilitating forensic practice. The underlying data for FROG-kb are provided by the already extensively used and referenced ALlele FREquency Database, ALFRED (http://alfred.med.yale.edu). In addition to displaying data in an organized manner, computational tools that use the underlying allele frequencies with user-provided data are implemented in FROG-kb. These tools are organized by the different published SNP/marker panels available. This web tool currently has implemented general functions possible for two types of SNP panels, individual identification and ancestry inference, and a prediction function specific to a phenotype informative panel for eye color. Conclusion The current online version of FROG-kb already provides new and useful functionality. We expect FROG-kb to grow and expand in capabilities and welcome input from the forensic community in identifying datasets and functionalities that will be most helpful and useful. Thus, the structure and functionality of FROG-kb will be revised in an ongoing process of improvement. This paper describes the state as of early June 2012. PMID:22938150

Exploring Episodic Affordance and Response in Children's Narratives Based on a Picture Book

ERIC Educational Resources Information Center

Hoel, Trude

2016-01-01

This article presents part of a research project where the aim is to investigate six- to seven-year-old children's language use in storytelling. The children's oral texts are based on the picture book "Frog, Where Are You?" The book consists of a series of episodes that more or less directly point to the plot structure. However, it also…

Inference of genetic network of Xenopus frog egg: improved genetic algorithm.

PubMed

Wu, Shinq-Jen; Chou, Chia-Hsien; Wu, Cheng-Tao; Lee, Tsu-Tian

2006-01-01

An improved genetic algorithm (IGA) is proposed to achieve S-system gene network modeling of Xenopus frog egg. Via the time-courses training datasets from Michaelis-Menten model, the optimal parameters are learned. The S-system can clearly describe activative and inhibitory interaction between genes as generating and consuming process. We concern the mitotic control in cell-cycle of Xenopus frog egg to realize cyclin-Cdc2 and Cdc25 for MPF activity. The proposed IGA can achieve global search with migration and keep the best chromosome with elitism operation. The generated gene regulatory networks can provide biological researchers for further experiments in Xenopus frog egg cell cycle control.

Take time to smell the frogs: vocal sac glands of reed frogs (Anura: Hyperoliidae) contain species-specific chemical cocktails

PubMed Central

Starnberger, Iris; Poth, Dennis; Peram, Pardha Saradhi; Schulz, Stefan; Vences, Miguel; Knudsen, Jette; Barej, Michael F; Rödel, Mark-Oliver; Walzl, Manfred; Hödl, Walter

2013-01-01

Males of all reed frog species (Anura: Hyperoliidae) have a prominent, often colourful, gular patch on their vocal sac, which is particularly conspicuous once the vocal sac is inflated. Although the presence, shape, and form of the gular patch are well-known diagnostic characters for these frogs, its function remains unknown. By integrating biochemical and histological methods, we found strong evidence that the gular patch is a gland producing volatile compounds, which might be emitted while calling. Volatile compounds were confirmed by gas chromatography–mass spectrometry in the gular glands in 11 species of the hyperoliid genera Afrixalus, Heterixalus, Hyperolius, and Phlyctimantis. Comparing the gular gland contents of 17 specimens of four sympatric Hyperolius species yielded a large variety of 65 compounds in species-specific combinations. We suggest that reed frogs might use a complex combination of at least acoustic and chemical signals in species recognition and mate choice. PMID:24277973

Danger Comes from All Fronts: Predator-Dependent Escape Tactics of Túngara Frogs

PubMed Central

Bulbert, Matthew W.; Page, Rachel A.; Bernal, Ximena E.

2015-01-01

The escape response of an organism is generally its last line of defense against a predator. Because the effectiveness of an escape varies with the approach behaviour of the predator, it should be advantageous for prey to alter their escape trajectories depending on the mode of predator attack. To test this hypothesis we examined the escape responses of a single prey species, the ground-dwelling túngara frog (Engystomops pustulosus), to disparate predators approaching from different spatial planes: a terrestrial predator (snake) and an aerial predator (bat). Túngara frogs showed consistently distinct escape responses when attacked by terrestrial versus aerial predators. The frogs fled away from the snake models (Median: 131°). In stark contrast, the frogs moved toward the bat models (Median: 27°); effectively undercutting the bat’s flight path. Our results reveal that prey escape trajectories reflect the specificity of their predators’ attacks. This study emphasizes the flexibility of strategies performed by prey to outcompete predators with diverse modes of attack. PMID:25874798

Elastic modulus of tree frog adhesive toe pads.

PubMed

Barnes, W Jon P; Goodwyn, Pablo J Perez; Nokhbatolfoghahai, Mohsen; Gorb, Stanislav N

2011-10-01

Previous work using an atomic force microscope in nanoindenter mode indicated that the outer, 10- to 15-μm thick, keratinised layer of tree frog toe pads has a modulus of elasticity equivalent to silicone rubber (5-15 MPa) (Scholz et al. 2009), but gave no information on the physical properties of deeper structures. In this study, micro-indentation is used to measure the stiffness of whole toe pads of the tree frog, Litoria caerulea. We show here that tree frog toe pads are amongst the softest of biological structures (effective elastic modulus 4-25 kPa), and that they exhibit a gradient of stiffness, being stiffest on the outside. This stiffness gradient results from the presence of a dense network of capillaries lying beneath the pad epidermis, which probably has a shock absorbing function. Additionally, we compare the physical properties (elastic modulus, work of adhesion, pull-off force) of the toe pads of immature and adult frogs.

Detecting fish parvalbumin with commercial mouse monoclonal anti-frog parvalbumin IgG.

PubMed

Chen, Lingyun; Hefle, Sue L; Taylor, Steve L; Swoboda, Ines; Goodman, Richard E

2006-07-26

Parvalbumin is a calcium-binding muscle protein that is highly conserved across fish species and amphibians. It is the major cross-reactive allergen associated with both fish and frog allergy. We used two-dimensional electrophoretic and immunoblotting techniques to investigate the utility of a commercial monoclonal anti-frog parvalbumin IgG for detecting parvalbumin present in some commonly consumed fish species. The 2D electrophoresis and immunoblots revealed species-specific differences in proteins that appear to represent various numbers of isoforms of parvalbumin in carp (5), catfish (3), cod (1) and tilapia (2). No parvalbumin was detected in yellowfin tuna. Based on minor differences in relative intensities of protein staining and immunodetection, parvalbumin isoforms may have slight differences in the epitope region recognized by the anti-frog parvalbumin antibody. These results suggest that the frog anti-parvalbumin antibody can be used as a valuable tool to detect parvalbumins from the fish tested in this study, except yellowfin tuna.

Membrane lipid layers vs. polarized water dominated by fixed ions: a comparative study of the effects of three macrocyclic ionophores on the K+ permeability of frog skeletal muscle, frog ovarian eggs, and human erythrocytes.

PubMed

Ling, G N; Ochsenfeld, M M

1986-01-01

The effects of 10(-7) M valinomycin, nonactin, and monactin on human erythrocytes, frog sartorius muscle, and frog ovarian oocytes in the presence of varying external K+ concentration were studied. The results showed essentially a consistent but relatively modest increase of the K+ permeability constant in cm/sec with all three antibiotics on human erythrocytes. No change in response to any one of the antibiotics was observed in frog muscles or in frog ovarian eggs. These results and reports of similar failure to demonstrate ionophore-mediated increase of K+ permeability in squid axon and inner membrane of the liver mitochondria led to the conclusion that lipid membrane barrier to ionic traffic may be significant in the human erythrocytes but even here one must regard the evidence as tentative. In contrast, for the majority of other cell types studied, the data indicate the primary, if not exclusive route of ion traffic, is via the nonlipid component of the cell membrane. The evidence that these nonlipid paths are the fixed charge-polarized water layer complex and that they cover much of the cell surface of many types of living cells was discussed.

Biophysical Properties of Frog Virus and Its Deoxyribonucleic Acid: Fate of Radioactive Virus in the Early Stage of Infection 1

PubMed Central

Smith, William R.; McAuslan, Brian R.

1969-01-01

Frog virus (FV-3) was banded by isopycnic centrifugation in cesium chloride, sucrose, or potassium tartrate. Two bands of infectivity were regularly found at positions in cesium chloride corresponding to densities of 1.26 and 1.30 g/cm3, respectively. Deoxyribonucleic acid from either band had the following characteristics: double-stranded; a Tm of 76.3 C in 0.1 SSC (0.015 m NaCl plus 0.015 m sodium citrate) and a buoyant density of 1.720 g/cm3 in cesium chloride, corresponding to a guanine plus cytosine content of 56 to 58% and a molecular weight of 130 × 106 daltons, determined by velocity sedimentation. These data, together with electron micrographs of sections of cells infected with material from either band suggest that two types of infectious frog virus particles exists, rather than a second virus in the frog virus stocks. The composition of frog virus was determined. It was found that highly purified preparations of frog virus were composed of 55.8% protein, 30.1% deoxyribonucleic acid, and 14.2% lipid. The kinetics of adsorption and uncoating of FV-3 was studied with radioactive virus. Uncoating is comparatively rapid and in contrast to poxvirus is unaffected by inhibitors of protein synthesis. Images PMID:4980848

The Neuro-Hormonal Control of Rapid Dynamic Skin Colour Change in an Amphibian during Amplexus

PubMed Central

Kindermann, Christina; Narayan, Edward J.; Hero, Jean-Marc

2014-01-01

Sexual signalling using dynamic skin colouration is a key feature in some vertebrates; however, it is rarely studied in amphibians. Consequently, little is known about the hormonal basis of this interesting biological phenomenon for many species. Male stony creek frogs (Litoria wilcoxii) are known to change dorsal colouration from brown to lemon yellow within minutes. This striking change is faster then what has been seen most amphibians, and could therefore be under neuronal regulation, a factor that is rarely observed in amphibians. In this study, we observed colour changes in wild frogs during amplexus to determine the natural timing of colour change. We also investigated the hypothesis that colour change is mediated by either reproductive or neuro- hormones. This was achieved by injecting frogs with epinephrine, testosterone, saline solution (control 1) or sesame oil (control 2). A non-invasive approach was also used wherein hormones and controls were administered topically. Male frogs turned a vivid yellow within 5 minutes of initiation of amplexus and remained so for 3–5 hours before rapidly fading back to brown. Epinephrine-treated frogs showed a significant colour change from brown to yellow within 5 minutes, however, testosterone-treated frogs did not change colour. Our results provide evidence of the role neuronal regulation plays in colour change systems. PMID:25470775

The effects of four arthropod diets on the body and organ weights of the leopard frog, Rana pipiens, during vitellogenesis.

PubMed

Lehman, G C

1978-12-01

Wild-caught adult Rana pipiens females were captured in midsummer and fed diets of crickets, flies sowbugs or wax moth larvae during a three-month period of active vitellogenesis. The cricket diet supported the most extensive body weight gain during this time and promoted a prolonged period of weight increase in an additional long-term study. Synchronous growth of the oocytes occurred in all four groups, but the ovaries and oviducts of cricket-fed animals were significantly larger than those of frogs on the other three diets. The significantly higher liver weights of frogs fed wax moth larvae may have reflected an augmentation of hepatic energy stores. Fat body weights were also highest in this group of animals. Frogs fed crickets and wax moth larvae possessed larger fat bodies than did the midsummer control animals killed immediately after their arrival in the laboratory. In contrast, frogs fed flies and sowbugs had smaller fat bodies than did the initial controls, suggesting that animals on these diets had utilized fat body lipid during vitellogenesis. Gastrocnemius and final body weights were lowest in frogs fed wax moth larvae. These findings may have reflected the nutritional content of the diet or the reduction in appetite frequently noted in these animals during observations of feeding behavior.

Habitat use and home range of the endangered gold-spotted pond frog (Rana chosenica).

PubMed

Ra, Nam-Yong; Sung, Ha-Cheol; Cheong, Seokwan; Lee, Jung-Hyun; Eom, Junho; Park, Daesik

2008-09-01

Because of their complex life styles, amphibians and reptiles living in wetlands require both aquatic and terrestrial buffer zones in their protected conservation areas. Due to steep declines in wild populations, the gold-spotted pond frog (Rana chosenica) is listed as vulnerable by the IUCN. However, lack of data about its movements and use of habitat prevents effective conservation planning. To determine the habitat use and home range of this species, we radio-tracked 44 adult frogs for 37 days between 10 July and 4 Nov. 2007 to observe three different populations in the breeding season, non-breeding season, and late fall. The gold-spotted pond frog was very sedentary; its daily average movement was 9.8 m. Frogs stayed close to breeding ponds (within 6.6 m), and did not leave damp areas surrounding these ponds, except for dormancy migration to terrestrial sites such as dried crop fields. The average distance of dormancy migration of seven frogs from the edge of their breeding ponds was 32.0 m. The average size of an individual's home range was 713.8 m(2) (0.07 ha). The year-round population home range, which accounts for the home ranges of a population of frogs, was determined for two populations to be 8,765.0 m(2) (0.88 ha) and 3,700.9 m(2) (0.37 ha). Our results showed that to conserve this endangered species, appropriately sized wetlands and extended terrestrial buffer areas surrounding the wetlands (at least 1.33 ha, diameter 130 m) should be protected.

Unfertilized frog eggs die by apoptosis following meiotic exit

PubMed Central

2011-01-01

Background A characteristic feature of frog reproduction is external fertilization accomplished outside the female's body. Mature fertilization-competent frog eggs are arrested at the meiotic metaphase II with high activity of the key meiotic regulators, maturation promoting factor (MPF) and cytostatic factor (CSF), awaiting fertilization. If the eggs are not fertilized within several hours of ovulation, they deteriorate and ultimately die by as yet unknown mechanism. Results Here, we report that the vast majority of naturally laid unfertilized eggs of the African clawed frog Xenopus laevis spontaneously exit metaphase arrest under various environmental conditions and degrade by a well-defined apoptotic process within 48 hours after ovulation. The main features of this process include cytochrome c release, caspase activation, ATP depletion, increase of ADP/ATP ratio, apoptotic nuclear morphology, progressive intracellular acidification, and egg swelling. Meiotic exit seems to be a prerequisite for execution of the apoptotic program, since (i) it precedes apoptosis, (ii) apoptotic events cannot be observed in the eggs maintaining high activity of MPF and CSF, and (iii) apoptosis in unfertilized frog eggs is accelerated upon early meiotic exit. The apoptotic features cannot be observed in the immature prophase-arrested oocytes, however, the maturation-inducing hormone progesterone renders oocytes susceptible to apoptosis. Conclusions The study reveals that naturally laid intact frog eggs die by apoptosis if they are not fertilized. A maternal apoptotic program is evoked in frog oocytes upon maturation and executed after meiotic exit in unfertilized eggs. The meiotic exit is required for execution of the apoptotic program in eggs. The emerging anti-apoptotic role of meiotic metaphase arrest needs further investigation. PMID:22195698

Yaxchilan's whistles

NASA Astrophysics Data System (ADS)

Velazquez, Roberto

2002-11-01

Eight clay whistles found buried in Small Acropolis temples (650-800 BC) of Yaxchilan were analyzed. The study was centered on three dual whistles with body shapes resembling those of frogs. A method developed in previous studies and evidence from several disciplines were applied. Experimental replicas were made to find possible ancient ways of construction and to test hypotheses. The Helmholtz equation for globular resonators was calculated, sound signals were analyzed with spectrograms, and radiated acoustic power in different modes was estimated (0.0005-0.003W). The power level indicates that whistles' sounds could not be heard well if they were played along with louder Mayan aerophones like those of Bonampak's mural band nor in noisy celebrations in big plazas. Clay frogs were adequate to be used in the Small Acropolis, in the Labyrinth and by big groups, surely related to religion. The whistles can sing like natural frogs and produce beats, and they might have been used to produce a chorus in ceremonies to the god Chaac to call for rain, in H-men rites, or in the infraworld where they were discovered.

Leap Frog and Time Step Sub-Cycle Scheme for Coupled Neutronics and Thermal-Hydraulic Codes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, S.

2002-07-01

As the result of the advancing TCP/IP based inter-process communication technology, more and more legacy thermal-hydraulic codes have been coupled with neutronics codes to provide best-estimate capabilities for reactivity related reactor transient analysis. Most of the coupling schemes are based on closely coupled serial or parallel approaches. Therefore, the execution of the coupled codes usually requires significant CPU time, when a complicated system is analyzed. Leap Frog scheme has been used to reduce the run time. The extent of the decoupling is usually determined based on a trial and error process for a specific analysis. It is the intent ofmore » this paper to develop a set of general criteria, which can be used to invoke the automatic Leap Frog algorithm. The algorithm will not only provide the run time reduction but also preserve the accuracy. The criteria will also serve as the base of an automatic time step sub-cycle scheme when a sudden reactivity change is introduced and the thermal-hydraulic code is marching with a relatively large time step. (authors)« less

A comparative ultrastructural analysis of spermatozoa in Pleurodema (Anura, Leptodactylidae, Leiuperinae).

PubMed

Cruz, Julio C; Ferraro, Daiana P; Farías, Alejandro; Santos, Julio S; Recco-Pimentel, Shirlei M; Faivovich, Julián; Hermida, Gladys N

2016-07-01

This study describes the spermatozoa of 10 of the 15 species of the Neotropical frog genus Pleurodema through transmission electron microscopy. The diversity of oviposition modes coupled with a recent phylogenetic hypothesis of Pleurodema makes it an interesting group for the study of ultrastructural sperm evolution in relation to fertilization environment and egg-clutch structure. We found that Pleurodema has an unusual variability in sperm morphology. The more variable structures were the acrosomal complex, the midpiece, and the tail. The acrosomal complex has all the structures commonly reported in hyloid frogs but with different degree of development of the subacrosomal cone. Regarding the midpiece, the variability is given by the presence or absence of the mitochondrial collar. Finally, the tail is the most variable structure, ranging from single (only axoneme) to more complex (presence of paraxonemal rod, cytoplasmic sheath, and undulating membrane), with the absence of the typical axial fiber present in hyloid frogs, also shared with some other genera of Leiuperinae. J. Morphol. 277:957-977, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Potential interactions among disease, pesticides, water quality and adjacent land cover in amphibian habitats in the United States.

PubMed

Battaglin, W A; Smalling, K L; Anderson, C; Calhoun, D; Chestnut, T; Muths, E

2016-10-01

To investigate interactions among disease, pesticides, water quality, and adjacent land cover, we collected samples of water, sediment, and frog tissue from 21 sites in 7 States in the United States (US) representing a variety of amphibian habitats. All samples were analyzed for >90 pesticides and pesticide degradates, and water and frogs were screened for the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) using molecular methods. Pesticides and pesticide degradates were detected frequently in frog breeding habitats (water and sediment) as well as in frog tissue. Fungicides occurred more frequently in water, sediment, and tissue than was expected based upon their limited use relative to herbicides or insecticides. Pesticide occurrence in water or sediment was not a strong predictor of occurrence in tissue, but pesticide concentrations in tissue were correlated positively to agricultural and urban land, and negatively to forested land in 2-km buffers around the sites. Bd was detected in water at 45% of sites, and on 34% of swabbed frogs. Bd detections in water were not associated with differences in land use around sites, but sites with detections had colder water. Frogs that tested positive for Bd were associated with sites that had higher total fungicide concentrations in water and sediment, but lower insecticide concentrations in sediments relative to frogs that were Bd negative. Bd concentrations on frog swabs were positively correlated to dissolved organic carbon, and total nitrogen and phosphorus, and negatively correlated to pH and water temperature. Data were collected from a range of locations and amphibian habitats and represent some of the first field-collected information aimed at understanding the interactions between pesticides, land use, and amphibian disease. These interactions are of particular interest to conservation efforts as many amphibians live in altered habitats and may depend on wetlands embedded in these landscapes to survive. Published by Elsevier B.V.

Cytological maps of lampbrush chromosomes of European water frogs (Pelophylax esculentus complex) from the Eastern Ukraine

PubMed Central

2013-01-01

Background Hybridogenesis (hemiclonal inheritance) is a kind of clonal reproduction in which hybrids between parental species are reproduced by crossing with one of the parental species. European water frogs (Pelophylax esculentus complex) represent an appropriate model for studying interspecies hybridization, processes of hemiclonal inheritance and polyploidization. P. esculentus complex consists of two parental species, P. ridibundus (the lake frog) and P. lessonae (the pool frog), and their hybridogenetic hybrid – P. esculentus (the edible frog). Parental and hybrid frogs can reproduce syntopically and form hemiclonal population systems. For studying mechanisms underlying the maintenance of water frog population systems it is required to characterize the karyotypes transmitted in gametes of parental and different hybrid animals of both sexes. Results In order to obtain an instrument for characterization of oocyte karyotypes in hybrid female frogs, we constructed cytological maps of lampbrush chromosomes from oocytes of both parental species originating in Eastern Ukraine. We further identified certain molecular components of chromosomal marker structures and mapped coilin-rich spheres and granules, chromosome associated nucleoli and special loops accumulating splicing factors. We recorded the dissimilarities between P. ridibundus and P. lessonae lampbrush chromosomes in the length of orthologous chromosomes, number and location of marker structures and interstitial (TTAGGG)n-repeat sites as well as activity of nucleolus organizer. Satellite repeat RrS1 was mapped in centromere regions of lampbrush chromosomes of the both species. Additionally, we discovered transcripts of RrS1 repeat in oocytes of P. ridibundus and P. lessonae. Moreover, G-rich transcripts of telomere repeat were revealed in association with terminal regions of P. ridibundus and P. lessonae lampbrush chromosomes. Conclusions The constructed cytological maps of lampbrush chromosomes of P. ridibundus and P. lessonae provide basis to define the type of genome transmitted within individual oocytes of P. esculentus females with different ploidy and from various population systems. PMID:23590698

Potential interactions among disease, pesticides, water quality and adjacent land cover in amphibian habitats in the United States

USGS Publications Warehouse

Battaglin, William A.; Smalling, Kelly L.; Anderson, Chauncey; Calhoun, Daniel L.; Chestnut, Tara E.; Muths, Erin L.

2016-01-01

To investigate interactions among disease, pesticides, water quality, and adjacent land cover, we collected samples of water, sediment, and frog tissue from 21 sites in 7 States in the United States (US) representing a variety of amphibian habitats. All samples were analyzed for > 90 pesticides and pesticide degradates, and water and frogs were screened for the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) using molecular methods. Pesticides and pesticide degradates were detected frequently in frog breeding habitats (water and sediment) as well as in frog tissue. Fungicides occurred more frequently in water, sediment, and tissue than was expected based upon their limited use relative to herbicides or insecticides. Pesticide occurrence in water or sediment was not a strong predictor of occurrence in tissue, but pesticide concentrations in tissue were correlated positively to agricultural and urban land, and negatively to forested land in 2-km buffers around the sites. Bd was detected in water at 45% of sites, and on 34% of swabbed frogs. Bd detections in water were not associated with differences in land use around sites, but sites with detections had colder water. Frogs that tested positive for Bd were associated with sites that had higher total fungicide concentrations in water and sediment, but lower insecticide concentrations in sediments relative to frogs that were Bd negative. Bd concentrations on frog swabs were positively correlated to dissolved organic carbon, and total nitrogen and phosphorus, and negatively correlated to pH and water temperature.Data were collected from a range of locations and amphibian habitats and represent some of the first field-collected information aimed at understanding the interactions between pesticides, land use, and amphibian disease. These interactions are of particular interest to conservation efforts as many amphibians live in altered habitats and may depend on wetlands embedded in these landscapes to survive.

Phylogeny and biogeography of South Chinese brown frogs (Ranidae, Anura).

PubMed

Zhou, Yu; Wang, Sirui; Zhu, Hedan; Li, Pipeng; Yang, Baotian; Ma, Jianzhang

2017-01-01

Few studies have explored the role of Cenozoic tectonic evolution in shaping the patterns and processes of extant animal distributions in and around East Asia. In this study, we selected South Chinese brown frogs as a model to examine the phylogenetic and biogeographical consequences of Miocene tectonic events within South China and its margins. We used mitochondrial and nuclear molecular data to reconstruct phylogenetic interrelationships among Chinese brown frogs using Bayesian and maximum likelihood analyses. The phylogeny results show that there are four main clades of Chinese brown frogs. Excepting the three commonly known Chinese brown frog species groups, R. maoershanensis forms an independent clade nearest to the R. japonica group. Phylogeny and P-distance analyses confirmed R. maoershanensis as a valid species. Among South Chinese brown frogs, there are four subclades associated with four geographical areas: (I) R. maoershanensis; (II) R. japonica; (III) R. chaochiaoensis; and (IV) other species of the R. longicrus species group. Divergence times, estimated using mitochondrial sequences, place the vicariance events among the four subclades in the middle to late Miocene epoch. Our results suggest that (1) South Chinese brown frogs originated due to a vicariance event separating them from the R. chensinensis species group at the time of the Geological movement (~18 million years ago, Ma) in southern Tibet and the Himalayan region; (2) the separation and speciation of R. maoershanensis from the R. japonica group occurred due to the dry climate at approximately 16 Ma; (3) South Chinese brown frogs migrated from South China to Japan at the time (~10.8 Ma) that the global sea-level fell and the East China Sea Shelf Basin was swamp facies, when a land gallery may have formed across the sea to connect the two areas; and (4) R. chaochiaoensis separated from other species of the R. longicrus species group during the uplift of the Tibetan Plateau at approximately 9.5 Ma.

Panamanian frog species host unique skin bacterial communities

PubMed Central

Belden, Lisa K.; Hughey, Myra C.; Rebollar, Eria A.; Umile, Thomas P.; Loftus, Stephen C.; Burzynski, Elizabeth A.; Minbiole, Kevin P. C.; House, Leanna L.; Jensen, Roderick V.; Becker, Matthew H.; Walke, Jenifer B.; Medina, Daniel; Ibáñez, Roberto; Harris, Reid N.

2015-01-01

Vertebrates, including amphibians, host diverse symbiotic microbes that contribute to host disease resistance. Globally, and especially in montane tropical systems, many amphibian species are threatened by a chytrid fungus, Batrachochytrium dendrobatidis (Bd), that causes a lethal skin disease. Bd therefore may be a strong selective agent on the diversity and function of the microbial communities inhabiting amphibian skin. In Panamá, amphibian population declines and the spread of Bd have been tracked. In 2012, we completed a field survey in Panamá to examine frog skin microbiota in the context of Bd infection. We focused on three frog species and collected two skin swabs per frog from a total of 136 frogs across four sites that varied from west to east in the time since Bd arrival. One swab was used to assess bacterial community structure using 16S rRNA amplicon sequencing and to determine Bd infection status, and one was used to assess metabolite diversity, as the bacterial production of anti-fungal metabolites is an important disease resistance function. The skin microbiota of the three Panamanian frog species differed in OTU (operational taxonomic unit, ~bacterial species) community composition and metabolite profiles, although the pattern was less strong for the metabolites. Comparisons between frog skin bacterial communities from Panamá and the US suggest broad similarities at the phylum level, but key differences at lower taxonomic levels. In our field survey in Panamá, across all four sites, only 35 individuals (~26%) were Bd infected. There was no clustering of OTUs or metabolite profiles based on Bd infection status and no clear pattern of west-east changes in OTUs or metabolite profiles across the four sites. Overall, our field survey data suggest that different bacterial communities might be producing broadly similar sets of metabolites across frog hosts and sites. Community structure and function may not be as tightly coupled in these skin symbiont microbial systems as it is in many macro-systems. PMID:26579083

Water balance of field-excavated aestivating Australian desert frogs, the cocoon-forming Neobatrachus aquilonius and the non-cocooning Notaden nichollsi (Amphibia: Myobatrachidae).

PubMed

Cartledge, Victoria A; Withers, Philip C; McMaster, Kellie A; Thompson, Graham G; Bradshaw, S Don

2006-09-01

Burrowed aestivating frogs of the cocoon-forming species Neobatrachus aquilonius and the non-cocooning species Notaden nichollsi were excavated in the Gibson Desert of central Australia. Their hydration state (osmotic pressure of the plasma and urine) was compared to the moisture content and water potential of the surrounding soil. The non-cocooning N. nichollsi was consistently found in sand dunes. While this sand had favourable water potential properties for buried frogs, the considerable spatial and temporal variation in sand moisture meant that frogs were not always in positive water balance with respect to the surrounding soil. The cocoon-forming N. aquilonius was excavated from two distinct habitat types, a claypan in which frogs had a well-formed cocoon and a dune swale where frogs did not have a cocoon. Cocoons of excavated frogs ranged in thickness from 19.4 microm to 55.61 microm and consisted of 81-229 layers. Cocooned claypan N. aquilonius were nearing exhaustion of their bladder water reserves and had a urine osmolality approaching that of the plasma. By contrast, non-cocooned N. aquilonius from the dune swale were fully hydrated, although soil moisture levels were not as high as calculated to be necessary to maintain water balance. Both species had similar plasma arginine vasotocin (AVT) concentrations ranging from 9.4 to 164 pg ml(-1), except for one cocooned N. aquilonius with a higher concentration of 394 pg ml(-1). For both species, AVT showed no relationship with plasma osmolality over the lower range of plasma osmolalities but was appreciably increased at the highest osmolality recorded. This study provides the first evidence that cocoon formation following burrowing is not obligatory in species that are capable of doing so, but that cocoon formation occurs when soil water conditions are more desiccating than for non-cocooned frogs.

Ovarian hyperstimulation syndrome in gonadotropin-treated laboratory South African clawed frogs (Xenopus laevis).

PubMed

Green, Sherril L; Parker, John; Davis, Corrine; Bouley, Donna M

2007-05-01

Ovarian hyperstimulation syndrome (OHS) is a rare but sometimes fatal iatrogenic complication of ovarian stimulation associated with the administration of exogenous gonadotropins to women undergoing treatment for infertility. Laboratory Xenopus spp are commonly treated with human chorionic gonadotropin (hCG) to stimulate ovulation and optimize the number of oocytes harvested for use in biomedical research. Here we report cases of OHS in 2 gonadotropin-treated laboratory Xenopus laevis. After receiving hCG, the frogs developed severe subcutaneous accumulation of fluid, coelomic distention, and whole-body edema and were unable to dive, although they continued to eat and swim. At postmortem examination, extensive subcutaneous edema was present; ascites and massive numbers of free-floating eggs were found in the coelomic cavity and in aberrant locations: around the heart-sac and adhered to the liver capsule. Whole-body edema, gross enlargement of the ovaries, ascites, and abdominal distention are findings comparable to those observed in women with OHS. The pathophysiology of OHS is thought to be related to hormonally induced disturbances of vasoactive mediators, one of which may be vascular endothelial growth factor secreted by theca and granulosa cells. We know of no other report describing OHSlike symptoms in gonadotropin-treated frogs, and the cases described here are 2 of the 3 we have observed at our respective institutions over the last 6 y. According to these results, OHS appears to be rare in gonadotropin-treated laboratory Xenopus. However, the condition should be included in the differential diagnosis for the bloated frog.

Suburbanization, estrogen contamination, and sex ratio in wild amphibian populations.

PubMed

Lambert, Max R; Giller, Geoffrey S J; Barber, Larry B; Fitzgerald, Kevin C; Skelly, David K

2015-09-22

Research on endocrine disruption in frog populations, such as shifts in sex ratios and feminization of males, has predominantly focused on agricultural pesticides. Recent evidence suggests that suburban landscapes harbor amphibian populations exhibiting similar levels of endocrine disruption; however the endocrine disrupting chemical (EDC) sources are unknown. Here, we show that sex ratios of metamorphosing frogs become increasingly female-dominated along a suburbanization gradient. We further show that suburban ponds are frequently contaminated by the classical estrogen estrone and a variety of EDCs produced by plants (phytoestrogens), and that the diversity of organic EDCs is correlated with the extent of developed land use and cultivated lawn and gardens around a pond. Our work also raises the possibility that trace-element contamination associated with human land use around suburban ponds may be contributing to the estrogenic load within suburban freshwaters and constitutes another source of estrogenic exposure for wildlife. These data suggest novel, unexplored pathways of EDC contamination in human-altered environments. In particular, we propose that vegetation changes associated with suburban neighborhoods (e.g., from forests to lawns and ornamental plants) increase the distribution of phytoestrogens in surface waters. The result of frog sex ratios varying as a function of human land use implicates a role for environmental modulation of sexual differentiation in amphibians, which are assumed to only have genetic sex determination. Overall, we show that endocrine disruption is widespread in suburban frog populations and that the causes are likely diverse.

Suburbanization, estrogen contamination, and sex ratio in wild amphibian populations

USGS Publications Warehouse

Lambert, Max R.; Giller, Geoffrey S. J.; Barber, Larry B.; Fitzgerald, Kevin C.; Skelly, David K.

2015-01-01

Research on endocrine disruption in frog populations, such as shifts in sex ratios and feminization of males, has predominantly focused on agricultural pesticides. Recent evidence suggests that suburban landscapes harbor amphibian populations exhibiting similar levels of endocrine disruption; however the endocrine disrupting chemical (EDC) sources are unknown. Here, we show that sex ratios of metamorphosing frogs become increasingly female-dominated along a suburbanization gradient. We further show that suburban ponds are frequently contaminated by the classical estrogen estrone and a variety of EDCs produced by plants (phytoestrogens), and that the diversity of organic EDCs is correlated with the extent of developed land use and cultivated lawn and gardens around a pond. Our work also raises the possibility that trace-element contamination associated with human land use around suburban ponds may be contributing to the estrogenic load within suburban freshwaters and constitutes another source of estrogenic exposure for wildlife. These data suggest novel, unexplored pathways of EDC contamination in human-altered environments. In particular, we propose that vegetation changes associated with suburban neighborhoods (e.g., from forests to lawns and ornamental plants) increase the distribution of phytoestrogens in surface waters. The result of frog sex ratios varying as a function of human land use implicates a role for environmental modulation of sexual differentiation in amphibians, which are assumed to only have genetic sex determination. Overall, we show that endocrine disruption is widespread in suburban frog populations and that the causes are likely diverse.

Evolutionary radiation of earless frogs in the Andes: molecular phylogenetics and habitat shifts in high-elevation terrestrial breeding frogs

PubMed Central

Lehr, Edgar; Rabosky, Daniel L.

2018-01-01

The loss of hearing structures and loss of advertisement calls in many terrestrial breeding frogs (Strabomantidae) living at high elevations in South America are common and intriguing phenomena. The Andean frog genus Phrynopus Peters, 1873 has undergone an evolutionary radiation in which most species lack the tympanic membrane and tympanic annulus, yet the phylogenetic relationships among species in this group remain largely unknown. Here, we present an expanded molecular phylogeny of Phrynopus that includes 24 nominal species. Our phylogeny includes Phrynopus peruanus, the type species of the genus, and 10 other species for which genetic data were previously unavailable. We found strong support for monophyly of Phrynopus, and that two nominal species—Phrynopus curator and Phrynopus nicoleae—are junior synonyms of Phrynopus tribulosus. Using X-ray computed tomography (CT) imaging, we demonstrate that the absence of external hearing structures is associated with complete loss of the auditory skeletal elements (columella) in at least one member of the genus. We mapped the tympanum condition on to a species tree to infer whether the loss of hearing structures took place once or multiple times. We also assessed whether tympanum condition, body size, and body shape are associated with the elevational distribution and habitat use. We identified a single evolutionary transition that involved the loss of both the tympanic membrane and tympanic annulus, which in turn is correlated with the absence of advertisement calls. We also identified several species pairs where one species inhabits the Andean grassland and the other montane forest. When accounting for phylogenetic relatedness among species, we detected a significant pattern of increasing body size with increasing elevation. Additionally, species at higher elevations tend to develop shorter limbs, shorter head, and shorter snout than species living at lower elevations. Our findings strongly suggest a link between ecological divergence and morphological diversity of terrestrial breeding frogs living in montane gradients. PMID:29492332

Ecological Guild Evolution and the Discovery of the World's Smallest Vertebrate

PubMed Central

Rittmeyer, Eric N.; Allison, Allen; Gründler, Michael C.; Thompson, Derrick K.; Austin, Christopher C.

2012-01-01

Living vertebrates vary drastically in body size, yet few taxa reach the extremely minute size of some frogs and teleost fish. Here we describe two new species of diminutive terrestrial frogs from the megadiverse hotspot island of New Guinea, one of which represents the smallest known vertebrate species, attaining an average body size of only 7.7 mm. Both new species are members of the recently described genus Paedophryne, the four species of which are all among the ten smallest known frog species, making Paedophryne the most diminutive genus of anurans. This discovery highlights intriguing ecological similarities among the numerous independent origins of diminutive anurans, suggesting that minute frogs are not mere oddities, but represent a previously unrecognized ecological guild. PMID:22253785

Unstable and multiple pulsing can be invisible to ultrashort pulse measurement techniques

DOE PAGES

Rhodes, Michelle A.; Guang, Zhe; Trebino, Rick

2016-12-29

Here, multiple pulsing occurs in most ultrashort-pulse laser systems when pumped at excessively high powers, and small fluctuations in pump power in certain regimes can cause unusual variations in the temporal separations of sub-pulses. Unfortunately, the ability of modern intensity-and-phase pulse measurement techniques to measure such unstable multi-pulsing has not been studied. Here we report calculations and simulations finding that allowing variations in just the relative phase of a satellite pulse causes the second pulse to completely disappear from a spectral interferometry for direct electric field reconstruction (SPIDER) measurement. We find that, although neither frequency-resolved optical gating (FROG) nor autocorrelationmore » can determine the precise properties of satellite pulses due to the presence of instability, they always succeed in, at least, seeing the satellite pulses. Also, additional post-processing of the measured FROG trace can determine the correct approximate relative height of the satellite pulse and definitively indicate the presence of unstable multiple-pulsing.« less

Unstable and multiple pulsing can be invisible to ultrashort pulse measurement techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rhodes, Michelle A.; Guang, Zhe; Trebino, Rick

Here, multiple pulsing occurs in most ultrashort-pulse laser systems when pumped at excessively high powers, and small fluctuations in pump power in certain regimes can cause unusual variations in the temporal separations of sub-pulses. Unfortunately, the ability of modern intensity-and-phase pulse measurement techniques to measure such unstable multi-pulsing has not been studied. Here we report calculations and simulations finding that allowing variations in just the relative phase of a satellite pulse causes the second pulse to completely disappear from a spectral interferometry for direct electric field reconstruction (SPIDER) measurement. We find that, although neither frequency-resolved optical gating (FROG) nor autocorrelationmore » can determine the precise properties of satellite pulses due to the presence of instability, they always succeed in, at least, seeing the satellite pulses. Also, additional post-processing of the measured FROG trace can determine the correct approximate relative height of the satellite pulse and definitively indicate the presence of unstable multiple-pulsing.« less

Genetic and maternal effect influences on viability of common frog tadpoles under different environmental conditions.

PubMed

Pakkasmaa, S; Merilä, J; O'Hara, R B

2003-08-01

The influence of environmental stress on the expression of genetic and maternal effects on the viability traits has seldom been assessed in wild vertebrates. We have estimated genetic and maternal effects on the viability (viz probability of survival, probability of being deformed, and body size and shape) of common frog, Rana temporaria, tadpoles under stressful (low pH) and nonstressful (neutral pH) environmental conditions. A Bayesian analysis using generalized linear mixed models was applied to data from a factorial laboratory experiment. The expression of additive genetic variance was independent of pH treatments, and all traits were significantly heritable (survival: h2 approximately 0.08; deformities: h2 approximately 0.26; body size: h2 approximately 0.12; body shape: h2 approximately 0.14). Likewise, nonadditive genetic contributions to variation in all traits were significant, independent of pH treatments and typically of magnitude similar to the additive genetic effects. Maternal effects were large for all traits, especially for viability itself, and their expression was partly dependent on the environment. In the case of body size, the maternal effects were mediated largely through egg size. In general, the results give little evidence for the conjecture that environmental stress created by low pH would impact strongly on the genetic architecture of fitness-related traits in frogs, and hamper adaptation to stress caused by acidification. The low heritabilities and high dominance contributions conform to the pattern typical for traits subject to relatively strong directional selection.

Atrazine increases the sodium absorption in frog (Rana esculenta) skin.

PubMed

Cassano, Giuseppe; Bellantuono, Vito; Ardizzone, Concetta; Lippe, Claudio

2006-02-01

The presence of atrazine in agricultural sites has been linked to the decline in amphibian populations. The efforts of the scientific community generally are directed toward investigating the long-term effect of atrazine on complex functions (reproduction or respiration), but in the present study, we investigated the short-term effect on the short-circuit current (I(sc)), a quantitative measure of the ion transport operated by frog (Rana esculenta) skin. Treatment with 5 microM atrazine (1.08 mg/L) does not affect the transepithelial outfluxes of [14C]mannitol or [14C]urea; therefore, atrazine does not damage the barrier properties of frog skin. Atrazine causes a dose-dependent increase in the short-circuit current, with a minimum of 4.64 +/- 0.76 microA/cm2 (11.05% +/- 1.22%) and a maximum of 12.7 +/- 0.7 microA/cm2 (35% +/- 2.4%) measured at 10 nM and 5 microM, respectively. An increase in Isc also is caused by 5 microM ametryne, prometryn, simazine, terbuthylazine, or terbutryn (other atrazine derivatives). In particular, atrazine increases the transepithelial 22Na+ influx without affecting the outflux. Finally, stimulation of Isc by atrazine is suppressed by SQ 22536, H89, U73122, 2-aminoethoxydiphenyl borate, and W7 (blockers of adenylate cyclase, protein kinase A, phospholipase C, intracellular Ca2+ increase, and calmodulin, respectively), whereas indomethacin and calphostin C (inhibitors of cyclooxygenase and protein kinase C, respectively) have no effect.

Pulse shape measurements using single shot-frequency resolved optical gating for high energy (80 J) short pulse (600 fs) laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palaniyappan, S.; Johnson, R.; Shimada, T.

2010-10-15

Relevant to laser based electron/ion accelerations, a single shot second harmonic generation frequency resolved optical gating (FROG) system has been developed to characterize laser pulses (80 J, {approx}600 fs) incident on and transmitted through nanofoil targets, employing relay imaging, spatial filter, and partially coated glass substrates to reduce spatial nonuniformity and B-integral. The device can be completely aligned without using a pulsed laser source. Variations of incident pulse shape were measured from durations of 613 fs (nearly symmetric shape) to 571 fs (asymmetric shape with pre- or postpulse). The FROG measurements are consistent with independent spectral and autocorrelation measurements.

The luteotrophic effect of homoplastic pituitary pars distalis homogenate, PMSG, and HCG on the corpora lutea of the hypophysectomized frog, Rana cyanophlyctis (SCHN).

PubMed

Pancharatna, M; Saidapur, S K

1984-03-01

The effect of homoplastic pituitary pars distalis homogenate (PDH), PMSG, and HCG on the postovulatory follicles/corpora lutea (CL) of the frog Rana cyanophlyctis was studied to elucidate the factors regulating the life span of the luteal cells. Ovulation and spawning was induced in hypophysectomized frogs using PDH. Starting from Day 1 of spawning 1/2 PDH, 50 IU PMSG, or 50 IU HCG was injected daily for 3 days. In the saline-injected control frogs, the granulosa lutein cells regressed markedly on Day 2 with a steady progressive increase in the pycnosis of their nuclei. The sudanophilic lipid droplets of the luteal cells were fine on Day 1 but became coarser and reduced in number on subsequent days. Histochemically, the luteal cell 3 beta-HSDH and G-6-PDH also decreased drastically by Day 2. In PDH-treated frogs the granulosa lutein cells were healthy on all 4 days of the experiment. The nuclear diameter of the luteal cells increased progressively due to PDH. The pycnosis of the luteal cells was limited to 7.6% on Day 4 due to PDH as opposed to 68% seen in the controls. Histochemically, 3 beta-HSDH and G-6-PDH activities remained much higher than in the controls with abundant sudanophilic lipids (both fine and coarse) in the luteal cells of PDH treated frogs even on Day 4. PMSG treatment also maintained the granulosa lutein cells beyond their normal life span but the luteotrophic effect was less than that of PDH. HCG was least effective. The present studies suggest that the structural integrity of CL in the frog can be extended beyond the normal life span by injecting PDH or PMSG.

Peptidomic analysis of skin secretions supports separate species status for the tailed frogs, Ascaphus truei and Ascaphus montanus

USGS Publications Warehouse

Conlon, J.M.; Bevier, C.R.; Coquet, L.; Leprince, J.; Jouenne, T.; Vaudry, H.; Hossack, B.R.

2007-01-01

The tailed frog Ascaphus truei Stejneger, 1899 is the most primitive extant anuran and the sister taxon to the clade of all other living frogs. The species occupies two disjunct ranges in the Northwest region of North America: the Cascade Mountains and coastal area from British Columbia to Northern California, and an inland range in the northern Rocky Mountains and the Blue and Wallowa mountains. A previous study led to the isolation of eight peptides with antimicrobial activity (termed the ascaphins) from skin secretions of A. truei from the coastal range. The present study has used peptidomic analysis to identify the products of orthologous ascaphin genes in electrically-stimulated skin secretions from inland range specimens. Structural characterization of the peptides demonstrated that ascaphins from the inland range contained the following amino acid substitutions compared with orthologs from the coastal range frogs: ascaphin-1 (Ala12 → Glu), ascaphin-3 (Asp4 → Glu), ascaphin-4 (Ala19 → Ser), ascaphin-5 (Lys12 → Thr), and ascaphin-7 (Gly8 → Ser and Ser20 → Asn). Orthologs of ascaphins-2, -6, and -8 were not identified but a paralog of ascaphin-5, identical to ascaphin-5 from coastal range frogs, was found. The data support the claims, derived from analysis of the nucleotide sequences of mitochondrial genes, that the inland populations of the tailed frog should be recognized as a distinct species, the Rocky Mountain tailed frog Ascaphus montanus and that the divergence of the species from A. truei probably occurred in the late Miocene (approximately 10 Mya).

Lead concentrations in bullfrog Rana catesbeiana and green frog R. clamitans tadpoles inhabiting highway drainages

USGS Publications Warehouse

Birdsall, C.W.; Grue, C.E.; Anderson, A.

1986-01-01

Lead concentrations were determined in sediment and tadpoles of bullfrogs Rana catesbeiana and green frogs R. clamitans from drainages along highways with different daily average traffic volumes (range, 4272 to I08,800 vehicles day-I) and from ponds >0.4 km from the nearest highway. Lead concentrations (mg kg--I dry weight) in sediment (7-8 to 940) were usually greater (4-5 times) than those in the tadpoles (bullfrog, 0,07 to 270; green frog, 0,90 to 240 mg kg-I). Lead concentrations in sediment (r =0.63) and in both species of tadpoles (bullfrog, r = 0.69; green frog, r = 0.57) were positively correlated with average daily traffic volume. Lead concentrations in both species of tadpoles (bullfrog, r = (). 76: green frog, r = 0.75) were also positively correlated with lead concentrations in sediment. At sites where both bullfrog and green frog tadpoles were collected. lead concentrations in the two species were closely related (r = 0.84). Lead concentrations in tadpoles living near highways may contribute to the elevated lead levels reported in wildlife that are potential tadpole predators. Dietary lead concentrations similar to those in our tadpoles have been associated with physiological and reproductive effects in some species of birds and mammals. However, additional data are needed to determine the hazards to predators of lead concentrations in tadpoles.

Comparison of isometric contractile properties of the tongue muscles in three species of frogs, Litoria caerulea, Dyscophus guinetti, and Bufo marinus.

PubMed

Peters, S E; Nishikawa, K C

1999-11-01

Previous studies show that anurans feed in at least three different ways. Basal frogs have a broad tongue that shortens during protraction and emerges only a short distance from the mouth. Some frogs have long, narrow tongues that elongate dramatically due primarily to inertia from mouth opening, which is transferred to the tongue. A few species have a hydrostatic mechanism that produces tongue elongation during protraction. This functional diversity occurs among frogs that share the same two pairs of tongue muscles. Our study compares the isometric contractile properties of these tongue muscles among three frog species that represent each feeding mechanism. Nerves to the paired protractors and retractors were stimulated electrically in each species to record the force properties, contraction speeds, and fatigabilites of these muscles. Few differences were found in the isometric contractile properties of tongue muscles, and the greatest differences were found in the retractors, not the protractors. We propose that the unique arrangement of the tongue muscles in frogs results in a retractor that may also be coactivated with the protractor in order to produce normal tongue protraction. Inertial effects from body, head, and jaw movements, along with clear differences that we found in passive resistance of the tongues to elongation, may explain much of the behavioral variation in tongue use among species. Copyright 1999 Wiley-Liss, Inc.

Diversity and abundance of forest frogs (Anura: Leptodactylidae) before and after Hurricane Georges in the Cordillera Central of Puerto Rico

USGS Publications Warehouse

Vilella, F.J.; Fogarty, J.H.

2005-01-01

Caribbean hurricanes often impact terrestrial vertebrates in forested environments. On 21 September 1998, Hurricane Georges impacted Puerto Rico with sustained winds in excess of 166 km/hr, causing damage to forests of the island's principal mountain range; the Cordillera Central. We estimated forest frog abundance and diversity from call counts conducted along marked transects before and after Hurricane Georges in two forests reserves of the Cordillera Central (Maricao and Guilarte). We used distance sampling to estimate density of Eleutherodactylus coqui and recorded counts of other species. After the hurricane, the abundance of E. coqui increased in both reserves compared to prehurricane levels while abundance of other frog species decreased. In Maricao, relative abundance of E. richmondi (P = 0.013) and E. brittoni (P = 0.034) were significantly lower after the hurricane. Moreover, species richness and evenness of the Maricao and Guilarte frog assemblages declined after the hurricane. Our results on abundance patterns of the forest frog assemblages of Maricao and Guilarte Forests were similar to those reported from the Luquillo Experimental Forest after Hurricane Hugo in September 1989. Long-term demographic patterns of the forest frog assemblages in the Cordillera Central may be associated with changes due to the ecological succession in post-hurricane forests. Copyright 2005 College of Arts and Sciences.

Effects of a fire on a population of treefrogs (Scinax cf. alter, Lutz) in a restinga habitat in southern Brazil.

PubMed

Rocha, C F D; Ariani, C V; Menezes, V A; Vrcibradic, D

2008-08-01

The area of the Dunas da Joaquina, in Santa Catarina island, contains one of the most important remnants of restinga habitat in Santa Catarina State, southern Brazil. In December 2003, a fire occurred in a portion of this area, affecting most of the vegetation, including the bromeliad community. In this study, the density of individuals and the diet composition of the bromelicolous treefrog Scinax cf. alter were compared between the area affected by the fire and an adjacent unburned area. One-hundred-and-fifty-eight ground bromeliads (Vriesea friburguensis) were dissected and searched for the presence of treefrogs among their leaves. We found 30 frogs in 29.5% (23/78) of the bromeliads from the unburned site, with a mean of 1.3 frogs per rosette, and 15 frogs in 12.5% (10/80) of the bromeliads from the burned site, with a mean of 1.6 frogs per rosette. Eight (27%) of the frogs from the unburned site and eleven (73%) of those from the burned site had empty stomachs. Frogs from the burned site also contained less prey per stomach than those from the unburned site. The data suggest that the fire has negatively affected the local population of Scinax cf. alter, though it is possible that the population can recover.

Frog sound identification using extended k-nearest neighbor classifier

NASA Astrophysics Data System (ADS)

Mukahar, Nordiana; Affendi Rosdi, Bakhtiar; Athiar Ramli, Dzati; Jaafar, Haryati

2017-09-01

Frog sound identification based on the vocalization becomes important for biological research and environmental monitoring. As a result, different types of feature extractions and classifiers have been employed to evaluate the accuracy of frog sound identification. This paper presents a frog sound identification with Extended k-Nearest Neighbor (EKNN) classifier. The EKNN classifier integrates the nearest neighbors and mutual sharing of neighborhood concepts, with the aims of improving the classification performance. It makes a prediction based on who are the nearest neighbors of the testing sample and who consider the testing sample as their nearest neighbors. In order to evaluate the classification performance in frog sound identification, the EKNN classifier is compared with competing classifier, k -Nearest Neighbor (KNN), Fuzzy k -Nearest Neighbor (FKNN) k - General Nearest Neighbor (KGNN)and Mutual k -Nearest Neighbor (MKNN) on the recorded sounds of 15 frog species obtained in Malaysia forest. The recorded sounds have been segmented using Short Time Energy and Short Time Average Zero Crossing Rate (STE+STAZCR), sinusoidal modeling (SM), manual and the combination of Energy (E) and Zero Crossing Rate (ZCR) (E+ZCR) while the features are extracted by Mel Frequency Cepstrum Coefficient (MFCC). The experimental results have shown that the EKNCN classifier exhibits the best performance in terms of accuracy compared to the competing classifiers, KNN, FKNN, GKNN and MKNN for all cases.

Assessing Antibacterial Potential of Components of Phyllomedusa distincta Skin and its Associated Dermal Microbiota.

PubMed

Brito de Assis, Ananda; Dos Santos, Cristiane; Dutra, Flávia Pereira; de Oliveira Motta, Ailla; Costa, Flávio Silva; Navas, Carlos Arturo; Magalhães, Beatriz Simas; Barreto, Cristine Chaves

2016-02-01

The granular glands of anuran skin secrete an array of bioactive molecules that protect a frog against pathogens and predators. The skin also harbors a microbial community. Although there is evidence to suggest that the microbiota complement the innate immune defense systems against pathogen infection, the effect of the frog bioactive molecules on its resident microbiota has not yet been fully investigated. In the present study, the skin microbiota of Phyllomedusa distincta obtained from two different geographical areas was evaluated with molecular and culture-based approaches. The antagonistic effects exhibited by the host's microbiota and by a novel dermaseptin peptide isolated from P. distincta skin were investigated. Four isolated bacterial colonies displayed antimicrobial activity against known frog pathogens. Our results were consistent with the hypothesis that microbiota from P. distincta may interact with pathogenic microorganisms to protect a frog's health. On the other hand, the novel dermaseptin peptide exhibited an antimicrobial effect on pathogens as well as on some of the bacteria obtained from the skin microbiota. The richness of bacteria on P. distincta skin was further investigated by 16S rRNA gene clone libraries, which revealed that the family Enterobacteriaceae was prevalent, but a high variability at the species level was observed among individual frogs. Differences observed on the microbiota of frogs from contrasting habitats indicated an influence of the environment on the structure of the skin microbiota of P. distincta.

Demography and movement in a relocated population of Oregon Spotted Frogs (Rana pretiosa): Influence of season and gender

USGS Publications Warehouse

Chelgren, N.D.; Pearl, C.A.; Adams, M.J.; Bowerman, J.

2008-01-01

We used five years of recapture data and Bayesian estimation to assess seasonal survival, movement, and growth of Oregon Spotted Frogs (Rana pretiosa) relocated into created ponds at Dilman Meadow in Oregon, USA. We evaluate hypotheses specific to the relocation and elucidate aspects of R. pretiosa life history that are poorly known. The odds of survival of relocated individuals during the first year following relocation were 0.36 times the survival odds of relocated and non-relocated frogs after one year since the relocation. Survival rate was higher for large frogs. After accounting for frog size, we found little variation in survival between ponds at Dilman Meadow. Survival was lowest for males during the breeding/post-breeding redistribution period, suggesting a high cost of breeding for males. The highest survival rates occurred during winter for both genders, and one small spring was used heavily during winter but was used rarely during the rest of the year. Individual growth was higher in ponds that were not used for breeding, and increased with increasing pond age. Our study supports other evidence that R. pretiosa use different habitats seasonally and are specific in their overwintering habitat requirements. Because frogs were concentrated during winter, predator-free overwintering springs are likely to be of particular value for R. pretiosa populations. ?? 2008 by the American Society of Ichthyologists and Herpetologists.

Antimicrobial peptides from frog skin: biodiversity and therapeutic promises.

PubMed

Ladram, Ali; Nicolas, Pierre

2016-06-01

More than a thousand antimicrobial peptides (AMPs) have been reported in the last decades arising from the skin secretion of amphibian species. Generally, each frog species can express its own repertoire of AMPs (typically, 10-20 peptides) with differing sequences, sizes, and spectrum of action, which implies very rapid divergence, even between closely related species. Frog skin AMPs are highly potent against antibiotic-resistant bacteria, protozoa, yeasts, and fungi by permeating and destroying their plasma membrane and/or inactivating intracellular targets. These peptides have attracted considerable interest as a therapeutic alternative to conventional anti-infective agents. However, efforts to obtain a new generation of drugs using these peptides are still challenging because of high associated R&D costs due to their large size (up to 46 residues) and cytotoxicity. This review deals with the biodiversity of frog skin AMPs and assesses the therapeutic possibilities of temporins, the shortest AMPs found in the frog skin, with 8-17 residues. Such short sequences are easily amenable to optimization of the structure and to solution-phase synthesis that offer reduced costs over solid-phase chemistry.

Response to Heethoff, Norton, and Raspotnig: Ant and Mite Diversity Drives Toxin Variation in the Little Devil Poison Frog and Erratum.

PubMed

McGugan, Jenna R; Byrd, Gary D; Roland, Alexandre B; Caty, Stephanie N; Kabir, Nisha; Tapia, Elicio E; Trauger, Sunia A; Coloma, Luis A; O'Connell, Lauren A

2016-08-01

Our recent publication titled "Ant and Mite Diversity Drives Toxin Variation in the Little Devil Poison Frog" aimed to describe how variation in diet contributes to population differences in toxin profiles of poison frogs. Some poison frogs (Family Dendrobatidae) sequester alkaloid toxins from their arthropod diet, which is composed mainly of ants and mites. Our publication demonstrated that arthropods from the stomach contents of three different frog populations were diverse in both chemistry and species composition. To make progress towards understanding this trophic relationship, our main goal was to identify alkaloids that are found in either ants or mites. With the remaining samples that were not used for chemical analysis, we attempted to identify the arthropods using DNA barcoding of cytochrome oxidase 1 (CO1). The critique of Heethoff, Norton, and Raspotnig refers to the genetic analysis of a small number of mites. Here, we respond to the general argument of the critique as well as other minor issues detailed by Heethoff, Norton, and Raspotnig.

Sexual dichromatism in frogs: natural selection, sexual selection and unexpected diversity.

PubMed

Bell, Rayna C; Zamudio, Kelly R

2012-12-07

Sexual dichromatism, a form of sexual dimorphism in which males and females differ in colour, is widespread in animals but has been predominantly studied in birds, fishes and butterflies. Moreover, although there are several proposed evolutionary mechanisms for sexual dichromatism in vertebrates, few studies have examined this phenomenon outside the context of sexual selection. Here, we describe unexpectedly high diversity of sexual dichromatism in frogs and create a comparative framework to guide future analyses of the evolution of these sexual colour differences. We review what is known about evolution of colour dimorphism in frogs, highlight alternative mechanisms that may contribute to the evolution of sexual colour differences, and compare them to mechanisms active in other major groups of vertebrates. In frogs, sexual dichromatism can be dynamic (temporary colour change in males) or ontogenetic (permanent colour change in males or females). The degree and the duration of sexual colour differences vary greatly across lineages, and we do not detect phylogenetic signal in the distribution of this trait, therefore frogs provide an opportunity to investigate the roles of natural and sexual selection across multiple independent derivations of sexual dichromatism.

Endoparasitic mites of the genus Endotrombicula Ewing, 1931 (Acari: Prostigmata: Parasitengona: Trombiculidae) from African and Madagascan anurans, with description of a new species.

PubMed

Wohltmann, Andreas; du Preez, Louis; Rödel, Mark-Oliver; Köhler, Jörn; Vences, Miguel

2007-09-01

A sample of over 6,000 specimens of frogs belonging to about 120 species of all families occurring in West Africa and Madagascar were screened for parasitic mites. Three species of Endotrombicula Ewing, 1931 were found in representatives of two African and two Madagascan frog families. All Trombiculidae found in African frogs belonged to Endotrombicula pillersi (Sambon, 1928), whereas in Madagascar E. madagascariensis (Sambon, 1928) and E. ptychadenae sp. n. were sampled. These three species are described, data about their parasitic associations are provided, and their zoogeographical distribution is discussed. Only those frog species that spend a considerable time in terrestrial ground habitats were parasitized; neither arboreal nor strictly aquatic frogs were infected. The geographic distribution of Endotrombicula, restricted to Africa, the Arabian Peninsula and Madagascar, suggests that these mites invaded Madagascar from the African continent. This is supported by the observation that the ancestors of Ptychadena mascareniensis (Duméril et Bibron) (Ptychadenidae), the host of E. ptychadenae, colonized Madagascar from the African continent quite recently, possibly accompanied by its Endotrombicula parasites.

Light and noise pollution interact to disrupt interspecific interactions.

PubMed

McMahon, Taegan A; Rohr, Jason R; Bernal, Ximena E

2017-05-01

Studies on the consequences of urbanization often examine the effects of light, noise, and heat pollution independently on isolated species providing a limited understanding of how these combined stressors affect species interactions. Here, we investigate how these factors interact to affect parasitic frog-biting midges (Corethrella spp.) and their túngara frog (Engystomops pustulosus) hosts. A survey of túngara frog calling sites revealed that frog abundance was not significantly correlated with urbanization, light, noise, or temperature. In contrast, frog-biting midges were sensitive to light pollution and noise pollution. Increased light intensity significantly reduced midge abundance at low noise levels. At high noise intensity, there were no midges regardless of light level. Two field experiments controlling light and noise levels to examine attraction of the midges to their host and their feeding behavior confirmed the causality of these field patterns. These findings demonstrate that both light and noise pollution disrupt this host-parasite interaction and highlight the importance of considering interactions among species and types of pollutants to accurately assess the impacts of urbanization on ecological communities. © 2017 by the Ecological Society of America.

Transcriptome resources for the frogs Lithobates clamitans and Pseudacris regilla, emphasizing antimicrobial peptides and conserved loci for phylogenetics

USGS Publications Warehouse

Robertson, Laura S.; Cornman, Robert S.

2014-01-01

We developed genetic resources for two North American frogs, Lithobates clamitans and Pseudacris regilla, widespread native amphibians that are potential indicator species of environmental health. For both species, mRNA from multiple tissues was sequenced using 454 technology. De novo assemblies with Mira3 resulted in 50 238 contigs (N50 = 687 bp) and 48 213 contigs (N50 = 686 bp) for L. clamitans and P. regilla, respectively, after clustering with CD-Hit-EST and purging contigs below 200 bp. We performed BLASTX similarity searches against the Xenopus tropicalis proteome and, for predicted ORFs, HMMER similarity searches against the Pfam-A database. Because there is broad interest in amphibian immune factors, we manually annotated putative antimicrobial peptides. To identify conserved regions suitable for amplicon resequencing across a broad taxonomic range, we performed an additional assembly of public short-read transcriptome data derived from two species of the genus Rana and identified reciprocal best TBLASTX matches among all assemblies. Although P. regilla, a hylid frog, is substantially more diverged from the ranid species, we identified 56 genes that were sufficiently conserved to allow nondegenerate primer design with Primer3. In addition to providing a foundation for comparative genomics and quantitative gene expression analysis, our results enable quick development of nuclear sequence-based markers for phylogenetics or population genetics.

Discovery of skin alkaloids in a miniaturized eleutherodactylid frog from Cuba.

PubMed

Rodríguez, Ariel; Poth, Dennis; Schulz, Stefan; Vences, Miguel

2011-06-23

Four phylogenetically independent lineages of frogs are currently known to sequester lipid-soluble skin alkaloids for which a dietary source has been demonstrated. We report here a remarkable fifth such instance, in Eleutherodactylus iberia and Eleutherodactylus orientalis, two species of miniaturized frogs of the family Eleutherodactylidae from Cuba. Six pumiliotoxins and two indolizidines were found in E. iberia, one of the smallest frogs in the world and characterized by a contrasting colour pattern for which we hypothesize an aposematic function. Analyses of stomach content indicated a numerical prevalence of mites with an important proportion of oribatids-a group of arthropods known to contain one of the pumiliotoxins detected in E. iberia. This suggests that miniaturization and specialization to small prey may have favoured the acquisition of dietary skin alkaloids in these amphibians.

Diseases of frogs and toads

USGS Publications Warehouse

Green, D.E.; Converse, K.A.; Majumdar, S.K.; Huffman, J.E.; Brenner, F.J.; Panah, A.I.

2005-01-01

This chapter presents information on infectious diseases of free-living frogs and toads that have completed metamorphosis. The diseases discussed in this chapter pertain principally to sub-adult and adult frogs and toads that are at least 60-90 days removed from completion of metamorphosis. The main emphasis of this chapter is the diseases found in amphibians of Canada and the United States. Diseases of recent metamorphs, larvae and amphibian eggs are presented in the chapters Diseases of Amphibian Eggs and Embryos and Diseases of Tadpoles. The smallest disease agents (viruses and bacteria) are presented first, followed by fungi, protozoa, helminths and ectoparasites. Diseases presented in this chapter are Ranaviral (iridovirus) infection Lucke frog herpesvirus (kidney cancer) Frog erythrocytic virus West Nile virus Red-leg disease (bacterial septicemia) Salmonellosis Chytrid fungal infection Basidiobolus fungi Dermosporidiosis Ichthyophoniasis Dermocystidium & Dermomycoides Myxozoa Ribeiroia flukes and Amphibian malformations Clinostomum metacercaria Aspects of each disease are presented to assist the biologist with recognition of diseases in the field. Hence, the major emphases for identification of diseases are the epizootiological aspects (host species, life stage, casualty numbers, etc) and gross findings ('lesions'). Descriptions of the microscopical, ultrastructural and cultural characteristics of each infectious agent were considered beyond the scope of this text. Detailed cultural and microscopical features of these disease agents are available in other reviews (Taylor et al., 2001; Green, 2001). Some diseases, while common in captive and zoo amphibians, are exceptionally rare in free-living frogs and toads, and therefore are omitted from this review. Among the diseases not presented are infections by chlamydia and mycobacteria, which occur principally in captive colonies of African clawed frogs (Xenopus, Hymenochirus, et al.) and northern leopard frogs (Rana pipiens). Other interesting diseases could have been presented, such as a wart-like virus infection of Japanese newts and a group of protistan parasites, referred to as Dermocystidium and Dermomycoides, in European frogs and toads. The reader is referred to Green (2001) for a review of these diseases. Amphibians have a rich diversity of helminthic parasites (Poynton and Whitaker, 2001). In general, most cestodes, trematodes and nematodes of amphibians are innocuous and not linked to specific clinical signs ('symptoms') or mortalities. An important major exception to this generalization is the trematode, Ribeiroia, which has been linked to numerous and bizarre malformations of frogs, toads and salamanders (Johnson et al., 1999, Johnson et al., 2001, Schotthoefer et al., 2003). Two genera of trematodal parasites are discussed in this chapter: Ribeiroia because they cause malformations and Clinostomum because they are large and produce visible lumps in the skin. For a review of amphibian helminths, the reader is referred to the text by Flynn (1973).

Welcome to Fermilab Frogs!

Science.gov Websites

continent except Antarctica! Endangered! In the Chicago region, volunteers have joined a nationwide effort to count frogs. The Chicago Wilderness organization enlists the help of volunteers to record the

IMMEDIATE EFFECTS OF X-IRRADIATION ON THE HEART OF THE FROG

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onkelinx, Cl.

1962-07-21

The effects of whole-body irradiations on the heartbeat of pithed frogs were studied. A strong bradycardia was observed after 1 to 5 min of irradiation and is reversible within 1 min after irradiation. A sino-auricular block was observed in some cases. No response was found in any of the frogs during the cold months. The effects of atropine, physostigmine, and eserine on the response were studied. The results suggest a vagal excitation or acetylcholine liberation from the irradiation. (D.L.C.)

California Red-legged Frog - Stipulated Injunction

EPA Pesticide Factsheets

EPA will make effects determinations and initiate consultation with the U.S. Fish and Wildlife Service, regarding the potential effects of 66 pesticide active ingredient registrations on the California red-legged frog.

36 CFR 7.35 - Buffalo National River.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Superintendent is prohibited. (b) Frogs, Turtles and Crayfish. (1) The Superintendent may designate times and locations and establish conditions governing the taking of frogs, turtles and crayfish for personal use. (2...

36 CFR 7.35 - Buffalo National River.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Superintendent is prohibited. (b) Frogs, Turtles and Crayfish. (1) The Superintendent may designate times and locations and establish conditions governing the taking of frogs, turtles and crayfish for personal use. (2...

36 CFR 7.35 - Buffalo National River.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Superintendent is prohibited. (b) Frogs, Turtles and Crayfish. (1) The Superintendent may designate times and locations and establish conditions governing the taking of frogs, turtles and crayfish for personal use. (2...

36 CFR 7.35 - Buffalo National River.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Superintendent is prohibited. (b) Frogs, Turtles and Crayfish. (1) The Superintendent may designate times and locations and establish conditions governing the taking of frogs, turtles and crayfish for personal use. (2...

36 CFR 7.35 - Buffalo National River.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Superintendent is prohibited. (b) Frogs, Turtles and Crayfish. (1) The Superintendent may designate times and locations and establish conditions governing the taking of frogs, turtles and crayfish for personal use. (2...

Adenomatous hyperplasia of the mucous glands in captive Archey's frogs (Leiopelma archeyi).

PubMed

Shaw, S D; Berger, L; Harvey, C; Alley, M R; Bishop, P J; Speare, R

2017-05-01

To describe the gross and light microscopic characteristics of skin lesions observed on the ventral skin of captive Archey's frogs (Leiopelma archeyi) between 2000 and 2012, and to investigate their occurrence, possible aetiology and association with survival. Postmortem skin samples were obtained for histological evaluation from 37 frogs, with and without skin lesions, that died while in captivity at Auckland Zoo between 2000 and 2012. Four frogs with skin lesions were biopsied under general anaesthesia and samples used for both light and transmission electron microscopy. The records of 94 frogs held at the University of Otago and Auckland Zoo between 2000-2012 were reviewed, which included some frogs recently collected from the wild. Information about the occurrence of skin lesions, and mortality associated with skin lesions was collated. Grossly the skin lesions varied in appearance; most were circular, pale grey papules, which measured from <0.5-1.5 mm in diameter with no umbilication. The overlying epidermis was not fragile and there was no associated inflammation. Contents often appeared clear or semi-transparent. Lesions were located predominantly on ventral surfaces including trunk, thighs, lower legs and forearms, and gular region, but not on digits. The number ranged from single to multiple, often confluent lesions covering the entire ventral surface of the frog. Histologically the lesions consisted of enlarged proliferating mucous glands that expanded the dermis and elevated the epidermis. They were semi-organised, solid or occasionally cavitated acinar structures with central lumina which sometimes contained mucus. Nuclei showed moderate anisokaryosis and mitotic figures were uncommon. Transmission electron microscopy did not show any infectious agents. Between 2000 and 2012, skin lesions were recorded in 35/94 (37%) frogs. The size and location of skin lesions varied over time, with some resolving and sometimes reappearing. Skin lesions were not associated with an increased risk of death. The skin lesions had the gross and microscopic characteristics of adenomatous hyperplasia of the dermal mucous glands. The aetiology of this adenomatous hyperplasia is unknown, but factors associated with the captive environment are the most likely cause. This is the first description of adenomatous hyperplasia of the cutaneous mucous glands in amphibians.

Effects on seventh-grade students' achievement and science anxiety of alternatives to conventional frog dissection

NASA Astrophysics Data System (ADS)

Marszalek, Christine Susan

1998-12-01

The purpose of this study in a suburban school district was to investigate and compare the level of learning and long-term retention of frog internal anatomy between seventh-grade students using an interactive CD tutorial, a desktop microworld, and conventional frog dissection. Students' anxiety toward science was also compared across the three treatment groups and between genders. Additional data on the students' preferred learning style were used to explore possible interaction effects with their respective instructional activity. Subjects participating in the study were all seventh-grade students in one junior-high school, numbering 280 in total. Classes were randomly assigned to the three modes of instruction for the dissection of a frog: a CD-tutorial dissection, a desktop microworld dissection, and a conventional dissection. The Conventional treatment was the traditional physical dissection using a preserved frog specimen and lab dissection tools. The CD-Tutorial treatment was the interactive tutorial Digital Frog from Digital Frog International. The Microworld treatment was a desktop microworld environment composed of Operation Frog on CD supplemented with other programs to provide additional avenues for learning. Data collection and testing occurred prior to treatment, one day after treatment, and three months after treatment. Data collected showed mixed results for all measures taken. The differences in achievement gained favoring the conventional treatment from pretest to both posttests appear to have leveled out somewhat over time. Although anxiety levels declined for both genders after treatment, females continued to report significantly higher science anxiety than males. There appears to be a relationship between treatment and gender in terms of effect on science anxiety. For all three measures taken--pretest, immediate posttest and delayed posttest--no significant difference in achievement by learning style was observed. Learning style alone does not appear to be related to achievement in this study. However, the interaction between learning style and treatment was significant in some cases. In looking at achievement defined as gain scores among the three achievement measures, only some cases within the microworld treatment proved to be significant.

Sexual and somatic development of wood frog tadpoles along a thermal gradient.

PubMed

Lambert, Max R; Smylie, Meredith S; Roman, Amber J; Freidenburg, L Kealoha; Skelly, David K

2018-02-01

All amphibian species are known to have genetic sex determination. However, a variety of environmental conditions can moderate sexual differentiation, in some cases leading to sex reversal and skewed sex ratios. While there has been a recent focus on chemically-induced sex reversal in amphibians, temperature can also influence sexual differentiation. Building upon a classic 1929 study by Emil Witschi, we assessed temperature-mediated sex reversal. Witschi found that the wood frog sex ratio is 100% male at a high temperature (32°C) compared to a 50:50 sex ratio at 20°C. This pattern is consistent with multiple models of environmentally mediated sexual differentiation in vertebrates. To better understand thermally mediated sex reversal, we raised wood frogs at temperature increments of ∼1°C between 19 and 34°C. Mirroring earlier findings, wood frog metamorph sex ratios are indistinguishable from 50:50 at the lowest temperature and entirely male at the highest temperatures. In between, sex ratios become increasingly male-dominated as temperatures increase, implying a steadily increasing tendency toward female-to-male sex reversal in warmer environments. There was no evidence of a threshold temperature effect on reversal patterns. We also show that, compared to males, females metamorphose larger and later in cooler conditions but earlier and smaller under warmer conditions. While the ecological relevance in this species is unknown, these results conform to the Charnov-Bull model of sex determination (in which female-to-male sex reversal can increase fitness to genetic females at higher temperatures), suggesting the system would reward further study. © 2018 Wiley Periodicals, Inc.

Causes of mortality in anuran amphibians from an ex situ survival assurance colony in Panama.

PubMed

Pessier, Allan P; Baitchman, Eric J; Crump, Paul; Wilson, Brad; Griffith, Edgardo; Ross, Heidi

2014-01-01

The success of ex situ survival assurance populations as tools for amphibian conservation depends on the health and reproductive success of founder populations. Necropsy examination and histopathology of animals that die in assurance populations are useful for the identification of population-limiting disease problems and can help to direct applied research efforts in areas such as amphibian husbandry and nutrition. This study reviewed postmortem findings in 167 frogs from 13 species that died in a large Panamanian rescue and survival assurance population between 2006 and 2011. Common problems identified in long-term captive animals, especially in Atelopus species, were epithelial squamous metaplasia suggestive of vitamin A deficiency and a polycystic nephropathy resembling lesions seen in laboratory animals with electrolyte imbalances. Metabolic bone disease was a significant contributor to morbidity in captive-bred juvenile frogs of Gastrotheca cornuta, Hemiphractus fasciatus, and Hylomantis lemur. Findings common to multiple species included poor overall nutritional condition that was sometimes attributable to maladaptation to captive husbandry and epidermal hyperplasia and hyperkeratosis possibly reflecting environmental skin irritation. Infectious diseases and endoparasitism were most common in recently captured animals and included chytridiomycosis and Rhabdias sp. lungworms. Applied research efforts to improve sustainability of survival assurance populations should focus on elucidating optimal husbandry practices for diverse species, improving methods for nutritional supplementation of cultured insects and examination of the role of water composition in disease development. © 2014 Wiley Periodicals Inc.

Targeted Modification of a Novel Amphibian Antimicrobial Peptide from Phyllomedusa tarsius to Enhance Its Activity against MRSA and Microbial Biofilm

PubMed Central

Gao, Yitian; Wu, Di; Wang, Lei; Lin, Chen; Ma, Chengbang; Xi, Xinping; Zhou, Mei; Duan, Jinao; Bininda-Emonds, Olaf R. P.; Chen, Tianbao; Shaw, Chris

2017-01-01

Antimicrobial peptides (AMPs) in the skin secretions of amphibians are fundamental components of a unique defense system that has evolved to protect these hosts from microbial invasion. Medusins constitute a recently-discovered AMP family from phyllomedusine leaf frog skin and exhibit highly-conserved structural characteristics. Here, we report a novel medusin, medusin-PT, from the skin secretion of the Tarsier Leaf Frog, Phyllomedusa tarsius. The mature peptide was initially identified from its cloned biosynthetic precursor-encoding cDNA as obtained by the rapid amplification of cDNA ends (RACE) method. Reverse-phase HPLC and tandem mass spectrometry confirmed both the presence of medusin-PT in the skin secretion and its primary structure. In a range of bioassays, medusin-PT exhibited antimicrobial activity against only the Gram-positive bacterium Staphylococcus aureus at 64 μg/ml. However, after directed changes to enhance the cationicity and amphipathicity of the peptide structure, three analog showed more potent antimicrobial activity against several additional bacteria including the antibiotic-resistant bacterium MRSA. In addition, these analog exhibited activity against microbial biofilm (minimum biofilm inhibitory and eradication concentrations of 32 μg/ml and over 64 μg/ml, respectively). These data provide evidence that medusins might be promising candidates as novel antibiotic leads and that the targeted modification of a natural AMP can both improve its efficacy so as to provide new insights into antibiotic design and development. PMID:28469603

Development and characterization of microsatellite markers for Brazilian four-eyed frogs (genus Pleurodema) endemic to the Caatinga biome.

PubMed

Thomé, M T C; Alexandrino, J; Lopes, S; Haddad, C F B; Sequeira, F

2014-03-12

We used pyrosequencing to develop microsatellite markers for the Brazilian four-eyed frog Pleurodema diplolister and tested the microsatellite markers for cross-amplification in its sister Pleurodema alium, which are both endemic species of the Caatinga biome in northeastern Brazil. We used multiplex sets to amplify and genotype 30 individuals of P. diplolister from three different populations and 10 individuals of P. alium from a single population. We successfully amplified 24 loci for P. diplolister, 13 of which we were able to amplify in P. alium. All loci were polymorphic. Significant deviations from the Hardy-Weinberg equilibrium and the presence of null alleles were only consistently detected at one locus (Pleu9). These markers will enable the study of geographic genetic diversity and evolutionary processes in these two Caatinga endemics, and the inclusion of genetic data for conservation planning of the Caatinga biome.

Comparative Postembryonic Skeletal Ontogeny in Two Sister Lineages of Old World Tree Frogs (Rhacophoridae: Taruga, Polypedates)

PubMed Central

Senevirathne, Gayani; Kerney, Ryan

2017-01-01

Rhacophoridae, a family of morphologically cryptic frogs, with many genetically distinct evolutionary lineages, is understudied with respect to skeletal morphology, life history traits and skeletal ontogeny. Here we analyze two species each from two sister lineages, Taruga and Polypedates, and compare their postembryonic skeletal ontogeny, larval chondrocrania and adult osteology in the context of a well-resolved phylogeny. We further compare these ontogenetic traits with the direct-developing Pseudophilautus silus. For each species, we differentially stained a nearly complete developmental series of tadpoles from early postembryonic stages through metamorphosis to determine the intraspecific and interspecific differences of cranial and postcranial bones. Chondrocrania of the four species differ in 1) size; 2) presence/absence of anterolateral and posterior process; and 3) shape of the suprarostral cartilages. Interspecific variation of ossification sequences is limited during early stages, but conspicuous during later development. Early cranial ossification is typical of other anuran larvae, where the frontoparietal, exoccipital and parasphenoid ossify first. The ossification sequences of the cranial bones vary considerably within the four species. Both species of Taruga show a faster cranial ossification rate than Polypedates. Seven cranial bones form when larvae near metamorphic climax. Ossification of all 18 cranial bones is initiated by larval Gosner stage 46 in T. eques. However, some cranial bone formation is not initiated until after metamorphosis in the other three species. Postcranial sequence does not vary significantly. The comparison of adult osteology highlights two characters, which have not been previously recorded: presence/absence of the parieto-squamosal plates and bifurcated base of the omosternum. This study will provide a starting point for comparative analyses of rhacophorid skeletal ontogeny and facilitate the study of the evolution of ontogenetic repatterning associated with the life history variation in the family. PMID:28060923

Prairie Resources

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Search Prairie Resources for Students Plant Database Plant Database Butterfly Info Butterfly Info Insects Insect Database Frogs Frog Info Bird Database Bird Database Online Prairie Data Online Prairie Data

Reciprocal Trophic Interactions and Transmission of Blood Parasites between Mosquitoes and Frogs

PubMed Central

Ferguson, Laura V.; Smith, Todd G.

2012-01-01

The relationship between mosquitoes and their amphibian hosts is a unique, reciprocal trophic interaction. Instead of a one-way, predator-prey relationship, there is a cyclical dance of avoidance and attraction. This has prompted spatial and temporal synchrony between organisms, reflected in emergence time of mosquitoes in the spring and choice of habitat for oviposition. Frog-feeding mosquitoes also possess different sensory apparatuses than do their mammal-feeding counterparts. The reciprocal nature of this relationship is exploited by various blood parasites that use mechanical, salivary or trophic transmission to pass from mosquitoes to frogs. It is important to investigate the involvement of mosquitoes, frogs and parasites in this interaction in order to understand the consequences of anthropogenic actions, such as implementing biocontrol efforts against mosquitoes, and to determine potential causes of the global decline of amphibian species. PMID:26466534

Discovery of skin alkaloids in a miniaturized eleutherodactylid frog from Cuba

PubMed Central

Rodríguez, Ariel; Poth, Dennis; Schulz, Stefan; Vences, Miguel

2011-01-01

Four phylogenetically independent lineages of frogs are currently known to sequester lipid-soluble skin alkaloids for which a dietary source has been demonstrated. We report here a remarkable fifth such instance, in Eleutherodactylus iberia and Eleutherodactylus orientalis, two species of miniaturized frogs of the family Eleutherodactylidae from Cuba. Six pumiliotoxins and two indolizidines were found in E. iberia, one of the smallest frogs in the world and characterized by a contrasting colour pattern for which we hypothesize an aposematic function. Analyses of stomach content indicated a numerical prevalence of mites with an important proportion of oribatids—a group of arthropods known to contain one of the pumiliotoxins detected in E. iberia. This suggests that miniaturization and specialization to small prey may have favoured the acquisition of dietary skin alkaloids in these amphibians. PMID:21047848

Origin of sex chromosomes in six groups of Rana rugosa frogs inferred from a sex-linked DNA marker.

PubMed

Oike, Akira; Watanabe, Koichiro; Min, Mi-Sook; Tojo, Koji; Kumagai, Masahide; Kimoto, Yuya; Yamashiro, Tadashi; Matsuo, Takanori; Kodama, Maho; Nakamura, Yoriko; Notsu, Masaru; Tochimoto, Takeyoshi; Fujita, Hiroyuki; Ota, Maki; Ito, Etsuro; Yasumasu, Shigeki; Nakamura, Masahisa

2017-08-01

Each vertebrate species, as a general rule, has either the XX/XY or ZZ/ZW chromosomes by which sex is determined. However, the Japanese Rana (R.) rugosa frog is an exception, possessing both sex-determining combinations within one species, varying with region of origin. We collected R. rugosa frogs from 104 sites around Japan and South Korea and determined the nucleotide sequences of the mitochondrial 12S ribosomal RNA gene. Based on the sequences, R. rugosa frogs were divided into four groups from Japan and one from South Korea. The ZZ/ZW type is reportedly derived from the XX/XY type, although recently a new ZZ/ZW type of R. rugosa was reported. However, it still remains unclear from where the sex chromosomes in the five groups of this species were derived. In this study, we successfully isolated a sex-linked DNA maker and used it to classify R. rugosa frogs into several groupings. From the DNA marker as well as from nucleotide analysis of the promoter region of the androgen receptor (AR) gene, we identified another female heterogametic group, designated, West-Central. The sex chromosomes in the West-Central originated from the West and Central groups. The results indicate that a sex-linked DNA marker is a verifiable tool to determine the origin of the sex chromosomes in R. rugosa frogs in which the sex-determining system has changed, during two independent events, from the male to female heterogamety. © 2017 Wiley Periodicals, Inc.

Comparison of diet, reproductive biology, and growth of the pig frog (Rana grylio) from harvested and protected areas of the Florida Everglades

USGS Publications Warehouse

Ugarte, C.A.; Rice, K.G.; Donnelly, M.A.

2007-01-01

Distinct differences in body size exist among three Rana grylio populations in areas of the Florida Everglades that differ in frog harvest pressure and hydroperiod. Frogs from two populations are harvested regularly throughout the year, while those in the third are protected from harvest. We compared seasonal and sex differences in diet, reproduction, and growth across these populations to examine life-history patterns. By volume, crayfish and anurans were the most abundant prey items for all adults across sites. Frogs from drier sites consumed more crayfish than frogs from the wettest site. Anurans were abundant in the diet during the wet season, while crayfish and fish were abundant during the dry season. More frogs with empty stomachs were captured during the wet season than the dry season. Feeding, growth, and fat deposition were greatest during the dry season across all sites. Although females were found in all reproductive stages throughout the year, the highest percentage of females had mature ova during the late dry season and spent ovaries during the early wet season. Individual patterns of growth were similar across all sites and matched historical growth data from the 1950s. Differences in body size among sites were most likely attributable to differential mortality (i.e., harvest pressure, predation) rather than to differences in food access or growth. ?? 2007 by the American Society of Ichthyologists and Herpetologists.

Low temperature tolerance, cold hardening and acclimation in tadpoles of the neotropical túngara frog (Engystomops pustulosus).

PubMed

Vo, Pacific; Gridi-Papp, Marcos

2017-05-01

Many frogs from temperate climates can tolerate low temperatures and increase their thermal tolerance through hardening and acclimation. Most tropical frogs, on the other hand, fail to acclimate to low temperatures. This lack of acclimation ability is potentially due to lack of selection pressure for acclimation because cold weather is less common in the tropics. We tested the generality of this pattern by characterizing the critical temperature minimum (CTMin), hardening, and acclimation responses of túngara frogs (Engystomops pustulosus). These frogs belong to a family with unknown thermal ecology. They are found in a tropical habitat with a highly constant temperature regime. The CTMin of the tadpoles was on average 12.5°C. Pre-metamorphic tadpoles hardened by 1.18°C, while metamorphic tadpoles hardened by 0.36°C. When raised at 21°C, tadpoles acclimated expanding their cold tolerance by 1.3°C in relation to larvae raised at 28°C. These results indicate that the túngara frog has a greatly reduced cold tolerance when compared to species from temperate climates, but it responds to cold temperatures with hardening and acclimation comparable to those of temperate-zone species. Cold tolerance increased with body length but cold hardening was more extensive in pre-metamorphic tadpoles than in metamorphic ones. This study shows that lack of acclimation ability is not general to the physiology of tropical anurans. Copyright © 2017 Elsevier Ltd. All rights reserved.

Factors influencing survival and mark retention in postmetamorphic boreal chorus frogs

USGS Publications Warehouse

Swanson, Jennifer E; Bailey, Larissa L.; Muths, Erin L.; Funk, W. Chris

2013-01-01

The ability to track individual animals is crucial in many field studies and often requires applying marks to captured individuals. Toe clipping has historically been a standard marking method for wild amphibian populations, but more recent marking methods include visual implant elastomer and photo identification. Unfortunately, few studies have investigated the influence and effectiveness of marking methods for recently metamorphosed individuals and as a result little is known about this life-history phase for most amphibians. Our focus was to explore survival probabilities, mark retention, and mark migration in postmetamorphic Boreal Chorus Frogs (Psuedacris maculata) in a laboratory setting. One hundred forty-seven individuals were assigned randomly to two treatment groups or a control group. Frogs in the first treatment group were marked with visual implant elastomer, while frogs in the second treatment group were toe clipped. Growth and mortality were recorded for one year and resulting data were analyzed using known-fate models in Program MARK. Model selection results suggested that survival probabilities of frogs varied with time and showed some variation among marking treatments. We found that frogs with multiple toes clipped on the same foot had lower survival probabilities than individuals in other treatments, but individuals can be marked by clipping a single toe on two different feet without any mark loss or negative survival effects. Individuals treated with visual implant elastomer had a mark migration rate of 4% and mark loss rate of 6%, and also showed very little negative survival impacts relative to control individuals.

Mine-drainage treatment wetland as habitat for herptofaunal wildlife

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lacki, M.J.; Hummer, J.W.; Webster, H.J.

Land reclamation techniques that incorporate habitat features for herptofaunal wildlife have received little attention. We assessed the suitability of a wetland, constructed for the treatment of mine-water drainage, for supporting herptofaunal wildlife from 1988 through 1990 using diurnal and nocturnal surveys. Natural wetlands within the surrounding watershed were also monitored for comparison. The treatment wetland supported the greatest abundance and species richness of herptofauna among the sites surveyed. Abundance was a function of the frog density, particularly green frogs (rana clamitans) and pickerel frogs (R. palustris), while species richness was due to the number of snake species found. The richmore » mix of snake species present at the treatment wetland was believed due to a combination of an abundant frog prey base and an amply supply of den sites in rock debris left behind from earlier surface-mining activities. Nocturnal surveys of breeding male frogs demonstrated highest breeding activity at the treatment wetland, particularly for spring peepers (Hyla crucifer). Whole-body assays of green frog and bullfrog (R. catesbeiana) tissues showed no differences among sites in uptake of iron, aluminum, and zinc; manganese levels in samples from the treatment wetland were significantly lower than those from natural wetlands. These results suggest that wetlands established for water quality improvement can provide habitat for reptiles and amplibians, with the species composition dependent on the construction design, the proximity to source populations, and the degree of acidity and heavy-metal concentrations in drainage waters. 35 refs., 4 tabs.« less

Sophisticated Communication in the Brazilian Torrent Frog Hylodes japi.

PubMed

de Sá, Fábio P; Zina, Juliana; Haddad, Célio F B

2016-01-01

Intraspecific communication in frogs plays an important role in the recognition of conspecifics in general and of potential rivals or mates in particular and therefore with relevant consequences for pre-zygotic reproductive isolation. We investigate intraspecific communication in Hylodes japi, an endemic Brazilian torrent frog with territorial males and an elaborate courtship behavior. We describe its repertoire of acoustic signals as well as one of the most complex repertoires of visual displays known in anurans, including five new visual displays. Previously unknown in frogs, we also describe a bimodal inter-sexual communication system where the female stimulates the male to emit a courtship call. As another novelty for frogs, we show that in addition to choosing which limb to signal with, males choose which of their two vocal sacs will be used for visual signaling. We explain how and why this is accomplished. Control of inflation also provides additional evidence that vocal sac movement and color must be important for visual communication, even while producing sound. Through the current knowledge on visual signaling in Neotropical torrent frogs (i.e. hylodids), we discuss and highlight the behavioral diversity in the family Hylodidae. Our findings indicate that communication in species of Hylodes is undoubtedly more sophisticated than we expected and that visual communication in anurans is more widespread than previously thought. This is especially true in tropical regions, most likely due to the higher number of species and phylogenetic groups and/or to ecological factors, such as higher microhabitat diversity.

Habitat fragmentation causes bottlenecks and inbreeding in the European tree frog (Hyla arborea).

PubMed Central

Andersen, Liselotte W.; Fog, Kåre; Damgaard, Christian

2004-01-01

A genetic study of the European tree frog, Hyla arborea, in Denmark was undertaken to examine the population structure on mainland Jutland and the island of Lolland after a period of reduction in suitable habitat and population sizes. The two regions have experienced the same rate of habitat loss but fragmentation has been more severe on Lolland. Genetic variation based on 12 polymorphic DNA microsatellites was analysed in 494 tree frogs sampled from two ponds in Jutland and 10 ponds on Lolland. A significant overall deviation from Hardy-Weinberg expectations could be attributed to three ponds, all on Lolland. This was most probably caused by an inbreeding effect reducing fitness, which was supported by the observed significant negative correlation between larva survival and mean F(IS) value and mean individual inbreeding coefficient. A significant reduction in genetic variation (bottleneck) was detected in most of the ponds on Lolland. Population-structure analysis suggested the existence of at least 11 genetically different populations, corresponding to most of the sampled population units. The results indicated that the populations were unique genetic units and could be used to illustrate the migration pattern between newly established ponds arisen either by natural colonization of tree frogs or by artificial introduction. A high degree of pond fidelity in the tree frogs was suggested. A severe fragmentation process reducing population size and fitness within some of the populations probably caused the significant reduction in genetic variation of tree frog populations on Lolland. PMID:15306354

Mine-drainage treatment wetland as habitat for herptofaunal wildlife

NASA Astrophysics Data System (ADS)

Lacki, Michael J.; Hummer, Joseph W.; Webster, Harold J.

1992-07-01

Land reclamation techniques that incorporate habitat features for herptofaunal wildlife have received little attention. We assessed the suitability of a wetland, constructed for the treatment of mine-water drainage, for supporting herptofaunal wildlife from 1988 through 1990 using diurnal and nocturnal surveys. Natural wetlands within the surrounding watershed were also monitored for comparison. The treatment wetland supported the greatest abundance and species richness of herptofauna among the sites surveyed. Abundance was a function of the frog density, particularly green frogs ( Rana clamitans) and pickerel frogs ( R. palustris), while species richness was due to the number of snake species found. The rich mix of snake species present at the treatment wetland was believed due to a combination of an abundant frog prey base and an amply supply of den sites in rock debris left behind from earlier surface-mining activities. Nocturnal surveys of breeding male frogs demonstrated highest breeding activity at the treatment wetland, particularly for spring peepers ( Hyla crucifer). Whole-body assays of green frog and bullfrog ( R. catesbeiana) tissues showed no differences among sites in uptake of iron, aluminum, and zinc; managanese levels in samples from the treatment wetland were significantly lower than those from natural wetlands. These results suggest that wetlands established for water quality improvement can provide habitat for reptiles and amphibians, with the species composition dependent on the construction design, the proximity to source populations, and the degree of acidity and heavy-metal concentrations in drainage waters.

Sophisticated Communication in the Brazilian Torrent Frog Hylodes japi

PubMed Central

de Sá, Fábio P.; Zina, Juliana; Haddad, Célio F. B.

2016-01-01

Intraspecific communication in frogs plays an important role in the recognition of conspecifics in general and of potential rivals or mates in particular and therefore with relevant consequences for pre-zygotic reproductive isolation. We investigate intraspecific communication in Hylodes japi, an endemic Brazilian torrent frog with territorial males and an elaborate courtship behavior. We describe its repertoire of acoustic signals as well as one of the most complex repertoires of visual displays known in anurans, including five new visual displays. Previously unknown in frogs, we also describe a bimodal inter-sexual communication system where the female stimulates the male to emit a courtship call. As another novelty for frogs, we show that in addition to choosing which limb to signal with, males choose which of their two vocal sacs will be used for visual signaling. We explain how and why this is accomplished. Control of inflation also provides additional evidence that vocal sac movement and color must be important for visual communication, even while producing sound. Through the current knowledge on visual signaling in Neotropical torrent frogs (i.e. hylodids), we discuss and highlight the behavioral diversity in the family Hylodidae. Our findings indicate that communication in species of Hylodes is undoubtedly more sophisticated than we expected and that visual communication in anurans is more widespread than previously thought. This is especially true in tropical regions, most likely due to the higher number of species and phylogenetic groups and/or to ecological factors, such as higher microhabitat diversity. PMID:26760304

Influence of Hepatozoon parasites on host-seeking and host-choice behaviour of the mosquitoes Culex territans and Culex pipiens.

PubMed

Ferguson, Laura V; Kirk Hillier, N; Smith, Todd G

2013-12-01

Hepatozoon species are heteroxenous parasites that commonly infect the blood of vertebrates and various organs of arthropods. Despite their ubiquity, little is known about how these parasites affect host phenotype, including whether or not these parasites induce changes in hosts to increase transmission success. The objectives of this research were to investigate influences of the frog blood parasite Hepatozoon clamatae and the snake blood parasite Hepatozoon sipedon on host-seeking and host-choice behaviour of the mosquitoes Culex territans and Culex pipiens, respectively. During development of H. sipedon in C. pipiens, significantly fewer infected mosquitoes fed on uninfected snakes compared to uninfected mosquitoes. When H. sipedon was mature in C. pipiens, the number of infected and uninfected C. pipiens that fed on snakes was not significantly different. Higher numbers of mosquitoes fed on naturally infected snakes and frogs compared to laboratory-reared, uninfected control animals. However, experiments using only laboratory-raised frogs revealed that infection did not significantly affect host choice by C. territans. Behaviour of C. pipiens in the presence of H. sipedon may increase transmission success of the parasite and provide the first evidence of phenotypic changes in the invertebrate host of Hepatozoon parasites.

Larval morphology and complex vocal repertoire of Rhacophorus helenae (Anura: Rhacophoridae), a rare flying frog from Vietnam.

PubMed

Vassilieva, Anna B; Gogoleva, Svetlana S; Poyarkov, Nikolay A Jr

2016-06-24

We present new data on the distribution, reproduction, larval morphology and vocalization of Rhacophorus helenae (Rhacophoridae), a narrowly distributed frog from southern Vietnam. Two new populations of R. helenae were discovered during field surveys in the lowland monsoon forests in Dong Nai and Ba Ria-Vung Tau provinces in 2010-2013. Spawning was observed in May 2013. Egg clutches containing small (2.3±0.1 mm) unpigmented eggs were embedded in a foam nest and suspended high on trees above temporary ponds. The tadpoles of R. helenae have a morphology typical of pond-dwelling Rhacophorus larvae with a moderate tail length and a labial tooth row formula of 5(2-5)/3. Postmetamorphic juveniles differed from adult frogs in the features of their coloration and less developed webbing. The complex vocal repertoire of R. helenae included five types of tonal, wideband and pulsed calls and several transitional signal types differentiated by frequency and amplitude parameters. Calls were uttered as singular signals (pulsed calls) or within non-stereotyped series of variable duration (other call types). The complex structure of the advertisement call markedly distinguishes R. helenae from other members of the Rhacophorus reinwardtii species complex.

Using stochastic epidemiological models to evaluate conservation strategies for endangered amphibians

PubMed Central

Griesemer, Marc; Petzold, Linda R.; Briggs, Cheryl J.

2017-01-01

Recent outbreaks of chytridiomycosis, the disease of amphibians caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), have contributed to population declines of numerous amphibian species worldwide. The devastating impacts of this disease have led researchers to attempt drastic conservation measures to prevent further extinctions and loss of biodiversity. The conservation measures can be labour-intensive or expensive, and in many cases have been unsuccessful. We developed a mathematical model of Bd outbreaks that includes the effects of demographic stochasticity and within-host fungal load dynamics. We investigated the impacts of one-time treatment conservation strategies during the disease outbreak that occurs following the initial arrival of Bd into a previously uninfected frog population. We found that for all versions of the model, for a large fraction of parameter space, none of the one-time treatment strategies are effective at preventing disease-induced extinction of the amphibian population. Of the strategies considered, treating frogs with antifungal agents to reduce their fungal load had the greatest likelihood of a beneficial outcome and the lowest risk of decreasing the persistence of the frog population, suggesting that this disease mitigation strategy should be prioritized over disinfecting the environment or reducing host density. PMID:28855388

Rana computatrix to human language: towards a computational neuroethology of language evolution.

PubMed

Arbib, Michael A

2003-10-15

Walter's Machina speculatrix inspired the name Rana computatrix for a family of models of visuomotor coordination in the frog, which contributed to the development of computational neuroethology. We offer here an 'evolutionary' perspective on models in the same tradition for rat, monkey and human. For rat, we show how the frog-like taxon affordance model provides a basis for the spatial navigation mechanisms that involve the hippocampus and other brain regions. For monkey, we recall two models of neural mechanisms for visuomotor coordination. The first, for saccades, shows how interactions between the parietal and frontal cortex augment superior colliculus seen as the homologue of frog tectum. The second, for grasping, continues the theme of parieto-frontal interactions, linking parietal affordances to motor schemas in premotor cortex. It further emphasizes the mirror system for grasping, in which neurons are active both when the monkey executes a specific grasp and when it observes a similar grasp executed by others. The model of human-brain mechanisms is based on the mirror-system hypothesis of the evolution of the language-ready brain, which sees the human Broca's area as an evolved extension of the mirror system for grasping.

Unearthing the Fossorial Tadpoles of the Indian Dancing Frog Family Micrixalidae.

PubMed

Senevirathne, Gayani; Garg, Sonali; Kerney, Ryan; Meegaskumbura, Madhava; Biju, S D

2016-01-01

Tadpoles of the monotypic Indian dancing frog family Micrixalidae have remained obscure for over 125 years. Here we report the discovery of the elusive tadpoles of Micrixalus herrei from the sand beds of a forested stream in southern Western Ghats, and confirm their identity through DNA barcoding. These actively burrowing tadpoles lead an entirely fossorial life from eggs to late metamorphic stages. We describe their internal and external morphological characters while highlighting the following features: eel-like appearance, extensively muscularized body and tail, reduced tail fins, skin-covered eyes, delayed development of eye pigmentation in early pre-metamorphic stages (Gosner stages 25-29), prominent tubular sinistral spiracle, large transverse processes on vertebrae II and III, ankylosed ribs on transverse processes of vertebra II, notochord terminating before the atlantal cotyle-occipital condyle junction, absence of keratodonts, serrated well-formed jaw sheaths, and extensive calcified endolymphatic sacs reaching sacrum posteriorly. The tadpole gut contains mostly fine sediments and sand. We discuss the eel-like morphology and feeding habits of M. herrei in the context of convergence with other well-known fossorial tadpoles. This discovery builds the knowledge base for further comparative analyses and conservation of Micrixalus, an ancient and endemic lineage of Indian frogs.

Rapid hydrogen ion uptake of rod outer segments and rhodopsin solutions on illumination

PubMed Central

Falk, G.; Fatt, P.

1966-01-01

1. Flash illumination of a suspension of frog rod outer segments or rhodopsin solution in contact with a platinum electrode produces a rapidly developing negative displacement of potential of the electrode (with respect to a reversible electrode). 2. The amplitude of the potential change varies inversely with the H+ buffering capacity of the medium. It is inferred that the response is due to an uptake of H+ by the rod outer segments or rhodopsin, with the platinum surface acting as a pH electrode. 3. Determination of the action spectrum shows that the response depends on the absorption of light by rhodopsin. 4. In frog rods one acid-binding group with a pK of about 7·9 is produced for each molecule of rhodopsin bleached, consistent with a rhodopsin concentration in frog rods of 1·7 mM. 5. It is suggested that the time course of the response with rhodopsin solutions reflects the kinetics of the conversion of metarhodopsin I to metarhodopsin II. 6. A slower time course of voltage change observed for suspensions of outer segments is attributable to the time required for the diffusion of H+ buffer out of the rods. PMID:5945249

Estrogenic exposure affects metamorphosis and alters sex ratios in the northern leopard frog (Rana pipiens): identifying critically vulnerable periods of development.

PubMed

Hogan, Natacha S; Duarte, Paula; Wade, Michael G; Lean, David R S; Trudeau, Vance L

2008-05-01

During the transformation from larval tadpole to juvenile frog, there are critical periods of metamorphic development and sex differentiation that may be particularly sensitive to endocrine disruption. The aim of the present study was to identify sensitive developmental periods for estrogenic endocrine disruption in the northern leopard frog (Rana pipiens) using short, targeted exposures to the synthetic estrogen, ethinylestradiol (EE2). Post-hatch tadpoles (Gosner stage 27) were exposed over five distinct periods of metamorphosis: early (stage 27-30), mid (stage 30-36), early and mid (stage 27-36), late (stage 36-42), and the entire metamorphic period (chronic; stage 27-42). For each period, animals were sampled immediately following the EE2 exposure and at metamorphic climax (stage 42). The effects of EE2 on metamorphic development and sex differentiation were assessed through measures of length, weight, developmental stage, days to metamorphosis, sex ratios and incidence of gonadal intersex. Our results show that tadpoles exposed to EE2 during mid-metamorphosis were developmentally delayed immediately following exposure and took 2 weeks longer to reach metamorphic climax. In the unexposed groups, there was low proportion (0.15) of intersex tadpoles at stage 30 and gonads appeared to be morphologically distinct (male and female) in all individuals by stage 36. Tadpoles exposed early in development displayed a strong female-biased sex ratio compared to the controls. Moreover, these effects were also seen at metamorphic climax, approximately 2-3 months after the exposure period, demonstrating that transient early life-stage exposure to estrogen can induce effects on the reproductive organs that persist into the beginning of adult life-stages.

Electrophysiological effects of calcitonin gene-related peptide in bull-frog and guinea-pig atrial myocytes.

PubMed Central

Ono, K; Giles, W R

1991-01-01

1. Electrophysiological effects of calcitonin gene-related peptide (CGRP) on action potentials and corresponding transmembrane currents in single myocytes from bull-frog and guinea-pig atria were studied using a whole-cell voltage-clamp method. 2. CGRP at relatively low concentrations increased the height of the action potential plateau in a dose-dependent manner in both bull-frog and guinea-pig myocytes. In addition, in bull-frog cells CGRP accelerated the early phase of repolarization, thus shortening the overall duration of the action potential. In contrast, in guinea-pig myocytes CGRP prolonged the action potential duration at all concentrations that were studied. 3. Voltage-clamp measurements demonstrated that CGRP increased transmembrane calcium current (ICa) in guinea-pig myocytes without a significant change in its voltage dependence. The ED50 value for this effect on ICa was 1.28 +/- 0.55 X 10(-8) M (n = 4). The time course of the inactivation of ICa was not affected by CGRP. 4. CGRP increased the delayed rectifier K+ current (IK) at relatively low concentrations in bull-frog atria, whereas relatively high concentrations were needed to increase IK in guinea-pig myocytes. This effect was observed even after complete inhibition of ICa. 5. CGRP had no significant effect on the inwardly rectifying background K+ current, IK1, even at very high concentrations. 6. Comparison of the time course of ICa augmentation in bull-frog and guinea-pig myocytes revealed an important difference in the effect of CGRP in these two types of cells. CGRP at maximal concentrations increased ICa transiently in bull-frog myocytes, whereas this response was sustained in guinea-pig myocytes. Isoprenaline (Iso) induced sustained increase in ICa in both species. When ICa was fully activated by Iso, CGRP at high concentrations strongly inhibited ICa in the bull-frog, whereas it had little effect on ICa in guinea-pig myocytes. 7. Intracellular application of GTP gamma S (guanosine 5'-O-(3-thiotriphosphate) 10(-4) M) greatly potentiated the CGRP effect on ICa; in contrast, GDP beta S (guanosine 5'-O-(2-thiodiphosphate), 2 x 10(-3) M) partially inhibited the CGRP-induced augmentation of ICa. Taken together, these results indicate that the stimulation of ICa by CGRP is mediated by a GTP-binding protein. 8. The observed dose-dependent changes in ICa and IK in bull-frog and guinea-pig myocytes can explain the different patterns of CGRP-induced changes in action potential shape in these two myocyte preparations. PMID:1905755

Variation in brain anatomy in frogs and its possible bearing on their locomotor ecology.

PubMed

Manzano, Adriana S; Herrel, Anthony; Fabre, Anne-Claire; Abdala, Virginia

2017-07-01

Despite the long-standing interest in the evolution of the brain, relatively little is known about variation in brain anatomy in frogs. Yet, frogs are ecologically diverse and, as such, variation in brain anatomy linked to differences in lifestyle or locomotor behavior can be expected. Here we present a comparative morphological study focusing on the macro- and micro-anatomy of the six regions of the brain and its choroid plexus: the olfactory bulbs, the telencephalon, the diencephalon, the mesencephalon, the rhombencephalon, and the cerebellum. We also report on the comparative anatomy of the plexus brachialis responsible for the innervation of the forelimbs. It is commonly thought that amphibians have a simplified brain organization, associated with their supposedly limited behavioral complexity and reduced motor skills. We compare frogs with different ecologies that also use their limbs in different contexts and for other functions. Our results show that brain morphology is more complex and more variable than typically assumed. Moreover, variation in brain morphology among species appears related to locomotor behavior as suggested by our quantitative analyses. Thus we propose that brain morphology may be related to the locomotor mode, at least in the frogs included in our analysis. © 2017 Anatomical Society.

Neglecting the call of the wild: Captive frogs like the sound of their own voice.

PubMed

Passos, Luiza Figueiredo; Garcia, Gerardo; Young, Robert John

2017-01-01

Acoustic communication is highly influential in the expression of social behavior by anuran amphibians, transmitting information about the individual's physical condition and motivation. We studied the phonotactic (approach movements) responses of wild and captive male golden mantella frogs to conspecific wild and captive playback calls to determine the impact of captivity on social behaviour mediated by vocalisations. Calls were recorded from one wild and two captive populations. Phonotaxis experiments were then conducted by attracting M. aurantiaca males across a PVC grid on the forest floor or enclosure floor to a speaker. For each playback, the following parameters were recorded to define the accuracy of phonotaxis: (1) number of jumps; (2) jump angles; (3) jump distances; (4) path straightness. During this experiment we observed that wild frogs had a similar behavioural (phonotaxis) response to calls independent of their source while frogs from Chester Zoo had a significantly stronger response to calls of other conspecifics held separately at Chester Zoo. The lack of appropriate phonotaxis response by captive bred frogs to the calls of wild conspecifics could have serious negative conservation implications, if the captive bred individuals were released back to the wild.

Sound imaging of nocturnal animal calls in their natural habitat.

PubMed

Mizumoto, Takeshi; Aihara, Ikkyu; Otsuka, Takuma; Takeda, Ryu; Aihara, Kazuyuki; Okuno, Hiroshi G

2011-09-01

We present a novel method for imaging acoustic communication between nocturnal animals. Investigating the spatio-temporal calling behavior of nocturnal animals, e.g., frogs and crickets, has been difficult because of the need to distinguish many animals' calls in noisy environments without being able to see them. Our method visualizes the spatial and temporal dynamics using dozens of sound-to-light conversion devices (called "Firefly") and an off-the-shelf video camera. The Firefly, which consists of a microphone and a light emitting diode, emits light when it captures nearby sound. Deploying dozens of Fireflies in a target area, we record calls of multiple individuals through the video camera. We conduct two experiments, one indoors and the other in the field, using Japanese tree frogs (Hyla japonica). The indoor experiment demonstrates that our method correctly visualizes Japanese tree frogs' calling behavior. It has confirmed the known behavior; two frogs call synchronously or in anti-phase synchronization. The field experiment (in a rice paddy where Japanese tree frogs live) also visualizes the same calling behavior to confirm anti-phase synchronization in the field. Experimental results confirm that our method can visualize the calling behavior of nocturnal animals in their natural habitat.

Investigation of frog abnormalities on national wildlife refuges in the Northeast U.S.

USGS Publications Warehouse

Eaton-Poole, L.; Pinkney, A.E.; Green, D.E.; Sutherland, D.R.; Babbitt, K.J.; ,

2003-01-01

To address concerns about frog abnormalities, the U.S. Fish and Wildlife Service examined over 3,643 frogs and toads on National Wildlife Refuges (NWRs) in the Northeast U.S. The objectives were to: 1) determine if certain refuges had sites where abnormalities were frequently observed; 2) evaluate if the prevalence of abnormalities at a site was consistent within a season and among years; and 3) investigate possible causes. Sampling was conducted from 1999 through 2001. A complete sample from a site consisted of ???50 metamorphs of one species. The prevalence of abnormalities ranged from 0 to 15% and fluctuated within season and among years. The most common external abnormalities were truncated limbs, and missing limbs, feet, and digits. Frogs with duplication of limb segments were rare (6). Based on radiographical examinations of 89 abnormal frogs, 55 had abnormalities due to trauma, 22 due to malformations, and 12 could not be classified. Metacercariae of the trematode Ribeiroia were detected in substantial numbers in two species from Iroquois NWR, with one specimen having supernumerary hindlimbs. We recommend continued sampling and integrated, causal evaluations on NWRs where the prevalence of abnormalities exceeds 5% or where the types of abnormalities warrant further study.

Natural disturbance reduces disease risk in endangered rainforest frog populations

PubMed Central

Roznik, Elizabeth A.; Sapsford, Sarah J.; Pike, David A.; Schwarzkopf, Lin; Alford, Ross A.

2015-01-01

Natural disturbances can drive disease dynamics in animal populations by altering the microclimates experienced by hosts and their pathogens. Many pathogens are highly sensitive to temperature and moisture, and therefore small changes in habitat structure can alter the microclimate in ways that increase or decrease infection prevalence and intensity in host populations. Here we show that a reduction of rainforest canopy cover caused by a severe tropical cyclone decreased the risk of endangered rainforest frogs (Litoria rheocola) becoming infected by a fungal pathogen (Batrachochytrium dendrobatidis). Reductions in canopy cover increased the temperatures and rates of evaporative water loss in frog microhabitats, which reduced B. dendrobatidis infection risk in frogs by an average of 11–28% in cyclone-damaged areas, relative to unaffected areas. Natural disturbances to the rainforest canopy can therefore provide an immediate benefit to frogs by altering the microclimate in ways that reduce infection risk. This could increase host survival and reduce the probability of epidemic disease outbreaks. For amphibian populations under immediate threat from this pathogen, targeted manipulation of canopy cover could increase the availability of warmer, drier microclimates and therefore tip the balance from host extinction to coexistence. PMID:26294048

Natural disturbance reduces disease risk in endangered rainforest frog populations.

PubMed

Roznik, Elizabeth A; Sapsford, Sarah J; Pike, David A; Schwarzkopf, Lin; Alford, Ross A

2015-08-21

Natural disturbances can drive disease dynamics in animal populations by altering the microclimates experienced by hosts and their pathogens. Many pathogens are highly sensitive to temperature and moisture, and therefore small changes in habitat structure can alter the microclimate in ways that increase or decrease infection prevalence and intensity in host populations. Here we show that a reduction of rainforest canopy cover caused by a severe tropical cyclone decreased the risk of endangered rainforest frogs (Litoria rheocola) becoming infected by a fungal pathogen (Batrachochytrium dendrobatidis). Reductions in canopy cover increased the temperatures and rates of evaporative water loss in frog microhabitats, which reduced B. dendrobatidis infection risk in frogs by an average of 11-28% in cyclone-damaged areas, relative to unaffected areas. Natural disturbances to the rainforest canopy can therefore provide an immediate benefit to frogs by altering the microclimate in ways that reduce infection risk. This could increase host survival and reduce the probability of epidemic disease outbreaks. For amphibian populations under immediate threat from this pathogen, targeted manipulation of canopy cover could increase the availability of warmer, drier microclimates and therefore tip the balance from host extinction to coexistence.

Skin microbes on frogs prevent morbidity and mortality caused by a lethal skin fungus.

PubMed

Harris, Reid N; Brucker, Robert M; Walke, Jenifer B; Becker, Matthew H; Schwantes, Christian R; Flaherty, Devon C; Lam, Brianna A; Woodhams, Douglas C; Briggs, Cheryl J; Vredenburg, Vance T; Minbiole, Kevin P C

2009-07-01

Emerging infectious diseases threaten human and wildlife populations. Altered ecological interactions between mutualistic microbes and hosts can result in disease, but an understanding of interactions between host, microbes and disease-causing organisms may lead to management strategies to affect disease outcomes. Many amphibian species in relatively pristine habitats are experiencing dramatic population declines and extinctions due to the skin disease chytridiomycosis, which is caused by the chytrid fungus Batrachochytrium dendrobatidis. Using a randomized, replicated experiment, we show that adding an antifungal bacterial species, Janthinobacterium lividum, found on several species of amphibians to the skins of the frog Rana muscosa prevented morbidity and mortality caused by the pathogen. The bacterial species produces the anti-chytrid metabolite violacein, which was found in much higher concentrations on frog skins in the treatments where J. lividum was added. Our results show that cutaneous microbes are a part of amphibians' innate immune system, the microbial community structure on frog skins is a determinant of disease outcome and altering microbial interactions on frog skins can prevent a lethal disease outcome. A bioaugmentation strategy may be an effective management tool to control chytridiomycosis in amphibian survival assurance colonies and in nature.

Neglecting the call of the wild: Captive frogs like the sound of their own voice

PubMed Central

Passos, Luiza Figueiredo; Garcia, Gerardo

2017-01-01

Acoustic communication is highly influential in the expression of social behavior by anuran amphibians, transmitting information about the individual’s physical condition and motivation. We studied the phonotactic (approach movements) responses of wild and captive male golden mantella frogs to conspecific wild and captive playback calls to determine the impact of captivity on social behaviour mediated by vocalisations. Calls were recorded from one wild and two captive populations. Phonotaxis experiments were then conducted by attracting M. aurantiaca males across a PVC grid on the forest floor or enclosure floor to a speaker. For each playback, the following parameters were recorded to define the accuracy of phonotaxis: (1) number of jumps; (2) jump angles; (3) jump distances; (4) path straightness. During this experiment we observed that wild frogs had a similar behavioural (phonotaxis) response to calls independent of their source while frogs from Chester Zoo had a significantly stronger response to calls of other conspecifics held separately at Chester Zoo. The lack of appropriate phonotaxis response by captive bred frogs to the calls of wild conspecifics could have serious negative conservation implications, if the captive bred individuals were released back to the wild. PMID:28732034

Next-generation foundations for special trackwork : phase I.

DOT National Transportation Integrated Search

2013-02-01

This report reviews the dynamic load environment and failure modes of special trackwork frog foundations. Key measurements taken under a 39,000-pound wheel load traffic at the Facility for Accelerated Service Testing were used to develop and calibrat...

Heavy point frog performance under passenger vehicles : final report.

DOT National Transportation Integrated Search

2016-06-01

Federal Railroad Administration contracted with the Transportation Technology Center, Inc., Pueblo, Colorado, to conduct an : investigation of passenger vehicle performance running through heavy point frog (HPF) up to speeds of 110 mph. A NUCARS : ...

The disappearing northern leopard frog (Lithobates pipiens): conservation genetics and implications for remnant populations in western Nevada

PubMed Central

Rogers, Serena D; Peacock, Mary M

2012-01-01

Global amphibian declines suggest a major shift in the amount and quality of habitat for these sensitive taxa. Many species that were once widespread are now experiencing declines either in part of or across their historic range. The northern leopard frog (Rana [Lithobates] pipiens] has undergone significant declines particularly in the western United States and Canada. Leopard frog population losses in Nevada are largely due to habitat fragmentation and the introduction of nonnative fish, amphibian, and plant species. Only two populations remain in the Truckee and Carson River watersheds of western Nevada which represents the western boundary of this species range. We used sequence data for an 812 base pair fragment of the mitochondrial NADH dehydrogenase 1 (ND1) gene to support a native origin for western Nevada populations. All frogs had a single haplotype (W07) from the distinct western North America ND1 haplotype clade. Data from seven polymorphic microsatellite loci show that Truckee and Carson River populations are highly differentiated from each other and from leopard frogs collected from eastern Nevada sites. Lack of gene flow among and distinct color morphs among the western Nevada populations likely predates the current geographical isolation. Comparisons with other peripheral L. pipiens populations show western Nevada populations have similar levels of gene diversity despite their contemporary isolation (HE 0.411, 0.482). Restoration of leopard frog populations in these watersheds will be challenging given well-entrenched nonnative bullfrog populations and major changes to the riparian zone over the past century. Declines of once common amphibian species has become a major conservation concern. Contemporary isolation of populations on a species range periphery such as the leopard frog populations in the Truckee and Carson rivers further exacerbate extirpation risk as these populations are likely to have fewer genetic resources to adaptively respond to rapidly changing biotic and abiotic environments. PMID:22957204

Breeding Guild Determines Frog Distributions in Response to Edge Effects and Habitat Conversion in the Brazil's Atlantic Forest.

PubMed

Ferreira, Rodrigo B; Beard, Karen H; Crump, Martha L

2016-01-01

Understanding the response of species with differing life-history traits to habitat edges and habitat conversion helps predict their likelihood of persistence across changing landscape. In Brazil's Atlantic Forest, we evaluated frog richness and abundance by breeding guild at four distances from the edge of a reserve: i) 200 m inside the forest, ii) 50 m inside the forest, iii) at the forest edge, and iv) 50 m inside three different converted habitats (coffee plantation, non-native Eucalyptus plantation, and abandoned pastures, hereafter matrix types). By sampling a dry and a wet season, we recorded 622 individual frogs representing 29 species, of which three were undescribed. Breeding guild (i.e. bromeliad, leaf-litter, and water-body breeders) was the most important variable explaining frog distributions in relation to edge effects and matrix types. Leaf-litter and bromeliad breeders decreased in richness and abundance from the forest interior toward the matrix habitats. Water-body breeders increased in richness toward the matrix and remained relatively stable in abundance across distances. Number of large trees (i.e. DBH > 15 cm) and bromeliads best explained frog richness and abundance across distances. Twenty species found in the interior of the forest were not found in any matrix habitat. Richness and abundance across breeding guilds were higher in the rainy season but frog distributions were similar across the four distances in the two seasons. Across matrix types, leaf-litter species primarily used Eucalyptus plantations, whereas water-body species primarily used coffee plantations. Bromeliad breeders were not found inside any matrix habitat. Our study highlights the importance of primary forest for bromeliad and leaf-litter breeders. We propose that water-body breeders use edge and matrix habitats to reach breeding habitats along the valleys. Including life-history characteristics, such as breeding guild, can improve predictions of frog distributions in response to edge effect and matrix types, and can guide more effective management and conservation actions.

Pesticide concentrations in frog tissue and wetland habitats in alandscape dominated by agriculture

USGS Publications Warehouse

Smalling, Kelly L.; Reeves, Rebecca; Muths, Erin L.; Vandever, Mark W.; Battaglin, William A.; Hladik, Michelle; Pierce, Clay L.

2015-01-01

Habitat loss and exposure to pesticides are likely primary factors contributing to amphibian decline in agricultural landscapes. Conservation efforts have attempted to restore wetlands lost through landscape modifications to reduce contaminant loads in surface waters and providing quality habitat to wildlife. The benefits of this increased wetland area, perhaps especially for amphibians, may be negated if habitat quality is insufficient to support persistent populations. We examined the presence of pesticides and nutrients in water and sediment as indicators of habitat quality and assessed the bioaccumulation of pesticides in the tissue of two native amphibian species Pseudacris maculata (chorus frogs) and Lithobates pipiens (leopard frogs) at six wetlands (3 restored and 3 reference) in Iowa, USA. Restored wetlands are positioned on the landscape to receive subsurface tile drainage water while reference wetlands receive water from overland run-off and shallow groundwater sources. Concentrations of the pesticides frequently detected in water and sediment samples were not different between wetland types. The median concentration of atrazine in surface water was 0.2 μg/L. Reproductive abnormalities in leopard frogs have been observed in other studies at these concentrations. Nutrient concentrations were higher in the restored wetlands but lower than concentrations thought lethal to frogs. Complex mixtures of pesticides including up to 8 fungicides, some previously unreported in tissue, were detected with concentrations ranging from 0.08 to 1500 μg/kg wet weight. No significant differences in pesticide concentrations were observed between species, although concentrations tended to be higher in leopard frogs compared to chorus frogs, possibly because of differences in life histories. Our results provide information on habitat quality in restored wetlands that will assist state and federal agencies, landowners, and resource managers in identifying and implementing conservation and management actions for these and similar wetlands in agriculturally dominated landscapes.

Breeding Guild Determines Frog Distributions in Response to Edge Effects and Habitat Conversion in the Brazil’s Atlantic Forest

PubMed Central

Ferreira, Rodrigo B.; Beard, Karen H.; Crump, Martha L.

2016-01-01

Understanding the response of species with differing life-history traits to habitat edges and habitat conversion helps predict their likelihood of persistence across changing landscape. In Brazil’s Atlantic Forest, we evaluated frog richness and abundance by breeding guild at four distances from the edge of a reserve: i) 200 m inside the forest, ii) 50 m inside the forest, iii) at the forest edge, and iv) 50 m inside three different converted habitats (coffee plantation, non-native Eucalyptus plantation, and abandoned pastures, hereafter matrix types). By sampling a dry and a wet season, we recorded 622 individual frogs representing 29 species, of which three were undescribed. Breeding guild (i.e. bromeliad, leaf-litter, and water-body breeders) was the most important variable explaining frog distributions in relation to edge effects and matrix types. Leaf-litter and bromeliad breeders decreased in richness and abundance from the forest interior toward the matrix habitats. Water-body breeders increased in richness toward the matrix and remained relatively stable in abundance across distances. Number of large trees (i.e. DBH > 15 cm) and bromeliads best explained frog richness and abundance across distances. Twenty species found in the interior of the forest were not found in any matrix habitat. Richness and abundance across breeding guilds were higher in the rainy season but frog distributions were similar across the four distances in the two seasons. Across matrix types, leaf-litter species primarily used Eucalyptus plantations, whereas water-body species primarily used coffee plantations. Bromeliad breeders were not found inside any matrix habitat. Our study highlights the importance of primary forest for bromeliad and leaf-litter breeders. We propose that water-body breeders use edge and matrix habitats to reach breeding habitats along the valleys. Including life-history characteristics, such as breeding guild, can improve predictions of frog distributions in response to edge effect and matrix types, and can guide more effective management and conservation actions. PMID:27272328

Pesticide concentrations in frog tissue and wetland habitats in a landscape dominated by agriculture.

PubMed

Smalling, Kelly L; Reeves, Rebecca; Muths, Erin; Vandever, Mark; Battaglin, William A; Hladik, Michelle L; Pierce, Clay L

2015-01-01

Habitat loss and exposure to pesticides are likely primary factors contributing to amphibian decline in agricultural landscapes. Conservation efforts have attempted to restore wetlands lost through landscape modifications to reduce contaminant loads in surface waters and providing quality habitat to wildlife. The benefits of this increased wetland area, perhaps especially for amphibians, may be negated if habitat quality is insufficient to support persistent populations. We examined the presence of pesticides and nutrients in water and sediment as indicators of habitat quality and assessed the bioaccumulation of pesticides in the tissue of two native amphibian species Pseudacris maculata (chorus frogs) and Lithobates pipiens (leopard frogs) at six wetlands (3 restored and 3 reference) in Iowa, USA. Restored wetlands are positioned on the landscape to receive subsurface tile drainage water while reference wetlands receive water from overland run-off and shallow groundwater sources. Concentrations of the pesticides frequently detected in water and sediment samples were not different between wetland types. The median concentration of atrazine in surface water was 0.2 μg/L. Reproductive abnormalities in leopard frogs have been observed in other studies at these concentrations. Nutrient concentrations were higher in the restored wetlands but lower than concentrations thought lethal to frogs. Complex mixtures of pesticides including up to 8 fungicides, some previously unreported in tissue, were detected with concentrations ranging from 0.08 to 1,500 μg/kg wet weight. No significant differences in pesticide concentrations were observed between species, although concentrations tended to be higher in leopard frogs compared to chorus frogs, possibly because of differences in life histories. Our results provide information on habitat quality in restored wetlands that will assist state and federal agencies, landowners, and resource managers in identifying and implementing conservation and management actions for these and similar wetlands in agriculturally dominated landscapes. Published by Elsevier B.V.

[Early stages of development of Trypanosoma rotatorium (Mayer, 1843) from peripheral blood and internal organs of Anurans Bufo bufo (Linnaeus) and Rana sp. (Anura)].

PubMed

Malysheva, M N

2014-01-01

The data on the fauna of trypanosomes of Anura of the Leningrad Province are given. The initial development stages of Trypanosoma rotatorium in peripheral blood and internal organs of the frog are described for the first time.

All about Animal Life Cycles. Animal Life for Children. [Videotape].

ERIC Educational Resources Information Center

2000

While watching the development from tadpole to frog, caterpillar to butterfly, and pup to wolf, children learn about the life cycles of animals, the different stages of development, and the average life spans of a variety of creatures. This videotape correlates to the following National Science Education Standards for Life Science: characteristics…

Uptake of arsenic and metals by tadpoles at an historically contaminated Texas site

USGS Publications Warehouse

Clark, D.R.; Cantu, R.; Cowman, D.F.; Maxson, D.J.

1998-01-01

On 14 May 1994, tadpoles were collected from Lateral Pond and Municipal Lake in Bryan, Texas. These waters are immediately downstream from Finfeather Lake which was directly contaminated during 53 years of industrial production of arsenic (As)-based cotton defoliants. The tadpoles contained elevated levels of arsenic, chromium (Cr) and zinc (Zn). As far as it is known, the mean concentrations of As (6.87 p.p.m. wet weight) and Cr (6.91 p.p.m. wet weight) in cricket frog (Acris crepitans) tadpoles were the highest ever reported in tadpoles. The Zn in the tadpoles exceeded the levels found in sediments by six to 11 times. The concentrations of As, Cr and Zn in Finfeather Lake in 1994 may have been toxic because tadpoles could not be found there. Ranid tadpoles and a newly transformed ranid frog found dead in Lateral Pond and Municipal Lake in 1994 may indicate that the elements reached toxic levels in some individual amphibians. The concentrations of As, Cr and Zn found in the tadpoles in this study might be toxic to predators. Mortality of turtles showing symptoms linked to chronic exposure to As was reported in Finfeather Lake in 1973. Turtles were not reported in Finfeather Lake again until 1996. Observations at Municipal Lake in 1994-1996 showed abundant tadpoles and turtles but no snakes, which also have not been seen at Finfeather Lake. This absence of snakes may indicate that their sensitivity or exposure to the existing contaminants is greater than that of frogs and turtles.

Incidence of climate on common frog breeding: Long-term and short-term changes

NASA Astrophysics Data System (ADS)

Neveu, André

2009-09-01

In Brittany (northwest France), the climate is showing a trend toward warming. This change is increasingly suspected to have a role in driving amphibian decline, but it is very difficult to determine at what level the climate affects the future of species. Recently, some studies have detected some direct effects on breeding phenology and indirect effects on energy allocation. The present study explores some of these effects on the common frog ( Rana temporaria) from 1984 to 2007. The results show two trends: a long-term change in breeding activities and a short-term influence due to the 2003 climatic anomaly. For the period of study, the start of egg-laying shows a precocity that was correlated with thermal conditions during the preceding 40 days as well as milder springs during the previous year. This degree of precocity is currently the highest found in Europe (+26.6 days). As a result of the 2003 heat wave, the clutch mean fecundity in 2004 was smaller than for other years, the fecundity rates were reduced and abortions were numerous (unlike other years). Moreover, young females were the smallest observed in recent years and some females seemed to exhibit a trade-off between fecundity and growth. Before or after egg-laying, female body condition and mean weight of mature ovules were both lower. The year 2005 appears as a transition period before the recovery in 2006-2007. The results show that climate warming endangers the vital rates of the common frog, while the 2003 climatic events seem more detrimental than the long-term warming trend.

Thermodynamic analysis of active sodium and potassium transport in the frog corneal epithelium.

PubMed

Candia, O A; Reinach, P S

1982-06-01

The formalism of linear nonequilibrium thermodynamics for a three-flow system was applied to the isolated frog corneal epithelium to study the coupling between metabolism and the Na-K transport system across this layer. There is little or no net ion transport across the isolated frog corneal epithelium bathed in Na2SO4 Ringer. Addition of amphotericin B to the tear side solution increases apical membrane permeability, which results in a net Na transport (from tear to stroma) and a net K transport in the opposite direction. Corneas were mounted in a modified Ussing chamber that permitted the simultaneous measurements of electrical parameters and O2 consumption by means of Clark-type oxygen electrodes. The overall degree of coupling, q, of the Na-K transport system to metabolism was calculated from measuring the suprabasal O2 consumption rate at "static head" and "level flow" conditions and by a second independent technique. Measurements of electrical conductance used in conjunction with other previously measured parameters allowed the calculation of the affinity, A, of the metabolic reaction driving transport, all phenomenological coefficients, and the electromotive forces of sodium (ENa) and potassium transport (EK). Values of q determined by the two techniques agreed (q = 0.80 and 0.84, respectively). This indicates incomplete coupling and a variable stoichiometric relationship among O2 consumption rate, net Na transport, and net K transport. The value calculated for A was 70.5 kcal.mol-1, for ENa 142.5 mV, and for EK -34.9 mV.

Next-generation foundations for special trackwork phase III : final report.

DOT National Transportation Integrated Search

2016-05-01

Transportation Technology Center, Inc. (TTCI) conducted a series of tests, funded by the Federal Railroad Administration, which evaluated the potential beneficial effects of various configurations of high angle frogs and frog foundations on wheel-rai...

Overwintered Bullfrog tadpoles negatively affect Salamanders and Anurans in native amphibian communities

USGS Publications Warehouse

Boone, M.D.; Little, E.E.; Semlitsch, R.D.

2004-01-01

We examined the interactive effects of overwintered Bullfrog (Rana catesbeiana) tadpoles and pond hydroperiod on a community of larval amphibians in outdoor mesocosms including American Toads (Bufo americanus), Southern Leopard Frogs (Rana sphenocephala), and Spotted Salamanders (Ambystoma maculatum) - species within the native range of Bullfrogs. Spotted Salamanders and Southern Leopard Frogs were negatively influenced by the presence of overwintered Bullfrogs. Spotted Salamanders had shorter larval periods and slightly smaller masses at metamorphosis, and Southern Leopard Frogs had smaller masses at metamorphosis when reared with Bullfrogs than without. Presence of overwintered Bullfrogs, however, did not significantly affect American Toads. Longer pond hydroperiods resulted in greater survival, greater size at metamorphosis, longer larval periods, and later time until emergence of the first metamorphs for Southern Leopard Frog tadpoles and Spotted Salamander larvae. Our study demonstrated that overwintered Bullfrog tadpoles can respond to changing pond hydroperiods and can negatively impact metamorphosis of native amphibians.

Acid-precipitation studies in Colorado and Wyoming: Interim report of surveys of Montane amphibians and water chemistry. Interim report, 1986-1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corn, P.S.; Stolzenburg, W.; Bury, R.B.

1989-06-01

Surveys for amphibians were conducted in the Rocky Mountains of northern Colorado and southern Wyoming from 1986 to 1988. The northern leopard frog (Rana pipiens) was present at only 12% of historically known localities, and the boreal toad (Bufo boreas) was present at 17% of known localities. Chorus frogs (Pseudacris triseriata) suffered a catastrophic decline in population size in one population monitored since 1961, but regionally, this species was observed in 64% of known localities. Tiger salamanders (Ambystoma tigrinum) and wood frogs (Rana sylvatica) were present at 45% and 69% of known localities respectively. Acid neutralizing capacity, pH, specific conductivity,more » and cation concentrations in water at amphibian localities were negatively correlated with elevation. Survival of wood frog embryos declined when exposed to aluminum concentrations.« less

[Comparative sensitivity of liver monoamine oxidases of frog and whitefish to some tricyclic compounds].

PubMed

Basova, I N; Iagodina, O V

2011-01-01

There is performed a comparative analysis of action of four acridine derivatives and of one xanthene derivative (pyronine G) on activity of liver monoamine oxidase (MAO) of two species of poikilothermal freshwater animals: a representative of amphibians--the common frog Rana temnporaria and a representative of the order Salmonidae--the European whitefish Coregonus lavaretus. The studied synthetic hexamerous tricyclic compounds show the irreversible character of inhibition of intermediate potency towards the enzyme from both biological sources. There are obtained qualitative and quantitative differences in the reactional ability and selectivity of action of the studied inhibitors for liver MAO of frog and whitefish. The obtained data of the inhibitory analysis with use of specific substrates are an indirect proof for the existence in liver of the studies frog species of two molecular forms, whereas in the whitefish liver--single molecular MAO form.

Allozyme comparison of three Trypanosoma species (Kinetoplastida: Trypanosomatidae) of toads and frogs by starch-gel electrophoresis.

PubMed

Martin, D S; Desser, S S; Hong, H

1992-04-01

Six metabolic enzymes, glucose-6-phosphate dehydrogenase, glucosephosphate isomerase, isocitrate dehydrogenase, malate dehydrogenase, phosphoglucomutase, and purine nucleoside phosphorylase, from clonal isolates of 3 presumptive species of Trypanosoma (T. fallisi, T. ranarum, and T. rotatorium) from 3 anuran hosts (Bufo americanus, Rana clamitans, and Rana catesbeiana) were compared using starch-gel electrophoresis. Although bands were shared among the different zymodemes of isolates of the same host genus, low genetic polymorphism of the enzyme loci was observed with few apparent shared bands between samples isolated from frogs and toads. A distance value calculated between toad and frog trypanosome isolates suggests the likelihood of long-time separation of species. Cluster analysis based on overall similarity distinguished the trypanosomes of toads and frogs as separate taxa, suggesting that host specificity and observed morphological differences are consistent with heritable allozyme differences.

The precarious persistence of the endangered Sierra Madre yellow-legged frog Rana muscosa in southern California, USA

USGS Publications Warehouse

Backlin, Adam R.; Hitchcock, Cynthia J.; Gallegos, Elizabeth A.; Yee, Julie L.; Fisher, Robert N.

2015-01-01

We conducted surveys for the Endangered Sierra Madre yellow-legged frog Rana muscosa throughout southern California to evaluate the current distribution and status of the species. Surveys were conducted during 2000–2009 at 150 unique streams and lakes within the San Gabriel, San Bernardino, San Jacinto, and Palomar mountains of southern California. Only nine small, geographically isolated populations were detected across the four mountain ranges, and all tested positive for the amphibian chytrid fungus Batrachochytrium dendrobatidis. Our data show that when R. muscosa is known to be present it is easily detectable (89%) in a single visit during the frog's active season. We estimate that only 166 adult frogs remained in the wild in 2009. Our research indicates that R. muscosa populations in southern California are threatened by natural and stochastic events and may become extirpated in the near future unless there is some intervention to save them.

Virtual, on-line, frog dissection vs. conventional laboratory dissection: A comparison of student achievement and teacher perceptions among honors, general ability, and foundations-level high school biology classes

NASA Astrophysics Data System (ADS)

Kopec, Ronald H.

2002-09-01

Dissecting animal specimens has long been a tradition in biology classes. Objections by students, based on religious or ethical grounds, have been raised regarding the dissections of animals in classroom laboratories. A number of states now have legal proceedings or statewide policies requiring that alternatives to the actual dissection of laboratory animal specimens be permitted in their school districts. Alternatives to actual dissections have been developed in recent years. For a variety of reasons, performing an actual or conventional animal dissection may not be a desirable option. The purpose of this study was to investigate how a virtual On-line frog dissection compares with an actual laboratory dissection. What were the perceptions of the teacher's using it? How does student achievement compare among three the different ability levels on a pre and posttest regarding basic frog anatomy? Is a virtual On-line dissection a suitable alternative for students who, for whatever reason, do not participate in the actual laboratory experience? The subjects consisted of 218 biology students among three different ability levels, in a Northeastern suburban high school. Approximately half of the student groups participated in a virtual On-line dissection, the other half in an actual laboratory dissection. A pretest of basic frog anatomy was administered to the students two days before and the posttest one day after their dissection experience. Data were analyzed using matched pairs t-Tests, Analysis of Variance, Tukey HSD, and Squared Curvilinear Coefficients. Survey questionnaires were administered to the teachers after the dissection experiences were completed. There were no significant differences found in achievement between the virtual and conventional dissection groups. There were significant differences found in achievement score means among the three ability levels. There was no significant interaction between gender and achievement. Perceptions of the teacher's facilitating the two instructional methods varied. The main area of agreement among them was that a virtual On-line frog dissection was a viable alternative for students who objected to doing a conventional dissection.

Binase and other microbial RNases as potential anticancer agents.

PubMed

Makarov, Alexander A; Kolchinsky, Alexander; Ilinskaya, Olga N

2008-08-01

Some RNases possess preferential cytotoxicity against malignant cells. The best known of these RNases, onconase, was isolated from frog oocytes and is in clinical trials as anticancer therapy. Here we propose an alternative platform for anticancer therapy based on T1 RNases of microbial origin, in particular binase from Bacillus intermedius and RNase Sa from Streptomyces aureofaciens. We discuss their advantages and the most promising directions of research for their potential clinical applications. (c) 2008 Wiley Periodicals, Inc.

Integrating copper toxicity and climate change to understand extinction risk to two species of pond-breeding anurans.

PubMed

Weir, Scott M; Scott, David E; Salice, Christopher J; Lance, Stacey L

2016-09-01

Chemical contamination is often suggested as an important contributing factor to amphibian population declines, but direct links are rarely reported. Population modeling provides a quantitative method to integrate toxicity data with demographic data to understand the long-term effects of contaminants on population persistence. In this study we use laboratory-derived embryo and larval toxicity data for two anuran species to investigate the potential for toxicity to contribute to population declines. We use the southern toad (Anaxyrus terrestris) and the southern leopard frog (Lithobates sphenocephalus) as model species to investigate copper (Cu) toxicity. We use matrix models to project populations through time and quantify extinction risk (the probability of quasi-extinction in 35 yr). Life-history parameters for toads and frogs were obtained from previously published literature or unpublished data from a long-term (>35 yr) data set. In addition to Cu toxicity, we investigate the role of climate change on amphibian populations by including the probability of early pond drying that results in catastrophic reproductive failure (CRF, i.e., complete mortality of all larval individuals). Our models indicate that CRF is an important parameter for both species as both were unable to persist when CRF probability was >50% for toads or 40% for frogs. Copper toxicity alone did not result in significant effects on extinction risk unless toxicity was very high (>50% reduction in survival parameters). For toads, Cu toxicity and high probability of CRF both resulted in high extinction risk but no synergistic (or greater than additive) effects between the two stressors occurred. For leopard frogs, in the absence of CRF survival was high even under Cu toxicity, but with CRF Cu toxicity increased extinction risk. Our analyses highlight the importance of considering multiple stressors as well as species differences in response to those stressors. Our models were consistently most sensitive to juvenile and adult survival, further suggesting the importance of terrestrial stages to population persistence. Future models will incorporate multiple wetlands with different combinations of stressors to understand if our results for a single wetland result in a population sink within the landscape. © 2016 by the Ecological Society of America.

Effects of the herbicides linuron and S-metolachlor on Perez's frog embryos.

PubMed

Quintaneiro, Carla; Soares, Amadeu M V M; Monteiro, Marta S

2018-03-01

Presence of pesticides in the environment and their possible effects on aquatic organisms are of great concern worldwide. The extensive use of herbicides in agricultural areas are one of the factors contributing to the known decline of amphibian populations. Thus, as non-target species, amphibians can be exposed in early life stages to herbicides in aquatic systems. In this context, this study aims to evaluate effects of increasing concentrations of two maize herbicides, linuron and S-metolachlor on embryos of the Perez' frog (Pelophylax perezi) during 192 h. Apical endpoints were determined for each herbicide: mortality, hatching rate, malformations and length. Frog embryos presented a LC 50 of 21 mg/l linuron and 37.5 mg/l S-metolachlor. Furthermore, sub-lethal concentrations of both herbicides affected normal embryonic development, delaying hatching, decreasing larvae length and causing several malformations. Length of larvae decreased with increasing concentrations of each herbicide, even at the lower concentrations tested. Malformations observed in larvae exposed to both herbicides were oedemas, spinal curvature and deformation, blistering and microphtalmia. Overall, these results highlight the need to assess adverse effects of xenobiotics to early life stages of amphibians regarding beside mortality the embryonic development, which could result in impairments at later stages. However, to unravel mechanisms involved in toxicity of these herbicides further studies regarding lower levels of biological organisation such as biochemical and genomic level should be performed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hibernal habitat selection by Wood Frogs (Lithobates sylvaticus) in a northern New England montane landscape

USGS Publications Warehouse

Groff, Luke A.; Calhoun, Aram J.K.; Loftin, Cynthia S.

2016-01-01

Poikilothermic species, such as amphibians, endure harsh winter conditions via freeze-tolerance or freeze-avoidance strategies. Freeze-tolerance requires a suite of complex, physiological mechanisms (e.g., cryoprotectant synthesis); however, behavioral strategies (e.g., hibernal habitat selection) may be used to regulate hibernaculum temperatures and promote overwintering survival. We investigated the hibernal ecology of the freeze-tolerant Wood Frog (Lithobates sylvaticus) in north-central Maine. Our objectives were to characterize the species hibernaculum microclimate (temperature, relative humidity), evaluate hibernal habitat selection, and describe the spatial arrangement of breeding, post-breeding, and hibernal habitats. We monitored 15 frogs during two winters (2011/12: N = 10; 2012/13: N = 5), measured hibernal habitat features at micro (2 m) and macro (10 m) spatial scales, and recorded microclimate hourly in three strata (hibernaculum, leaf litter, ambient air). We compared these data to that of 57 random locations with logistic regression models, Akaike Information Criterion, and Kolmogorov–Smirnov tests. Hibernaculum microclimate was significantly different and less variable than leaf litter, ambient air, and random location microclimate. Model averaging indicated that canopy cover (−), leaf litter depth (+), and number of logs and stumps (+; microhabitat only) were important predictors of Wood Frog hibernal habitat. These habitat features likely act to insulate hibernating frogs from extreme and variable air temperatures. For example, decreased canopy cover facilitates increased snowpack depth and earlier snowpack accumulation and melt. Altered winter temperature and precipitation patterns attributable to climate change may reduce snowpack insulation, facilitate greater temperature variation in the underlying hibernacula, and potentially compromise Wood Frog winter survival.

Effects of water management, connectivity, and surrounding land use on habitat use by frogs in rice paddies in Japan.

PubMed

Naito, Risa; Yamasaki, Michimasa; Lmanishi, Ayumi; Natuhara, Yosihiro; Morimoto, Yukihiro

2012-09-01

In Japan, rice paddies play an important role as a substitute habitat for wetland species, and support rich indigenous ecosystems. However, since the 1950s, agricultural modernization has altered the rice paddy environment, and many previously common species are now endangered. It is urgently necessary to evaluate rice paddies as habitats for conservation. Among the species living in rice paddies, frogs are representative and are good indicator species, so we focused on frog species and analyzed the influence of environmental factors on their habitat use. We found four frog species and one subspecies (Hyla japonica, Pelophylax nigromaculatus, Glandirana rugosa, Lithobates catesbeianus, and Pelophylax porosa brevipoda) at our study sites in Shiga prefecture. For all but L. catesbeianus, we analyzed the influence of environmental factors related to rice paddy structure, water management and availability, agrochemical use, connectivity, and land use on breeding and non-breeding habitat use. We constructed generalized additive mixed models with survey date as the smooth term and applied Akaike's information criterion to choose the bestranked model. Because life histories and biological characteristics vary among species, the factors affecting habitat use by frogs are also expected to differ by species. We found that both breeding and non-breeding habitat uses of each studied species were influenced by different combinations of environmental factors and that in most cases, habitat use showed seasonality. For frog conservation in rice paddies, we need to choose favorable rice paddy in relation to surrounding land use and apply suitable management for target species.

Tricaine (MS-222) is a safe anesthetic compound compared to benzocaine and pentobarbital to induce anesthesia in leopard frogs (Rana pipiens).

PubMed

Cakir, Yavuz; Strauch, Stephen M

2005-01-01

Tricaine (MS-222) is used commonly for sedation, immobilization, and anesthesia of poikilothermic animals. The anesthetic efficacy of different concentrations of MS-222 was compared to benzocaine and pentobarbital on the physiological changes, heart rate and ECG (electrocardiogram) parameters in the leopard frog, Rana pipiens. Loss of righting reflex (RR), loss of pain response (NR = nociceptor response) and recovery time were measured. Heart rate and ECG parameters were also tested before and during anesthesia. The time to loss of RR and NR decreased while recovery time markedly increased with the increasing concentration of MS-222. Benzocaine at 200 mg/l induced a rapid anesthesia, but all frogs needed resuscitation. Pentobarbital at 300 mg/l induced a slow anesthesia, however, all of the frogs also needed resuscitation. All anesthetics at the mentioned concentrations decreased heart rate significantly as well as altered the ECG parameters. All anesthetics prolonged the Q-T interval, and MS-222 at 800 mg/l and benzocaine at 200 mg/l were the most effective anesthetic concentrations in increasing the Q-T interval. Frogs anesthetized by benzocaine and pentobarbital and high concentrations of MS-222 required resuscitation due to hypoxia. Pentobarbital and benzocaine seem to be very effective compounds, but their safety margins are narrow because of ventilatory failure. Therefore, MS-222 at a concentration of 200 mg/l or less is highly recommended for leopard frogs because prolonged recovery, high mortality rate and significant ECG changes are observed with higher concentrations of MS-222.

Interactions of an insecticide with competition and pond drying in amphibian communities

USGS Publications Warehouse

Boone, M.D.; Semlitsch, R.D.

2002-01-01

Amphibian populations are often imbedded in agricultural landscapes. Therefore the potential for contamination of their habitat is considerable. Our study examined the effects of an insecticide (carbaryl, a neurotoxin), on larval amphibian communities experiencing natural stresses of competition for resources, predation, and pond drying. In a set of experimental ponds, tadpoles of three anuran species (southern leopard frog [Rana sphenocephala], plains leopard frog [R. blairi], and the Woodhouse's toad [Bufo woodhousii]) were added to 1000-L ponds containing leaf litter, plankton, two newts (Notophthalmus viridescens), and four overwintered green frog (R. clamitans) tadpoles. We manipulated the overall tadpole density (low or high), pond hydroperiod (constant or drying), and chemical exposure (0, 3.5, 5.0, or 7.0 mg/L carbaryl) of the ponds. We measured mass, time, and survival to metamorphosis to determine treatment effects. Carbaryl positively affected Woodhouse's toad survival, although it had a negligible effect on both leopard frog species. Tadpole density interacted with the chemical treatment: Proportionately more Woodhouse's toads survived to metamorphosis in high-density environments than in low-density or control environments. Greater survival may be an indirect effect of increased algal food resources from carbaryl exposure. Most newts lost mass over the course of the experiment, although ponds with drying hydroperiods and high anuran density were the least favorable environments. Overwintered green frogs exposed to carbaryl had longer larval periods on average than did green frogs in control ponds. Our study demonstrated that even sublethal, short-lived contaminants can alter natural communities in ways that cannot be predicted from simple, one-factor studies.

A comparative study of charge movement in rat and frog skeletal muscle fibres.

PubMed

Hollingworth, S; Marshall, M W

1981-12-01

1. The middle of the fibre voltage--clamp technique (Adrian & Marshall, 1977), modified where necessary for electrically short muscle fibres, has been used to measure non-linear charge movements in mammalian fast twitch (rat extensor digitorum longus), mammalian slow twitch (rat soleus) and frog (sartorius) muscles. 2. The maximum amount of charge moved in mammalian fast twitch muscle at 2 degrees C in hypertonic solution, was 3--5 times greater than in slow twitch muscle. The voltage distribution of fast twitch charge was 10--15 mV more positive when compared to slow twitch. 3. In both mammalian muscle types hypertonic Ringer solution negatively shifted the voltage distribution of charge some 6 mV. The steepness of charge moved around mechanical threshold was unaffected by hypertonicity. 4. The amount of charge in frog sartorius fibres at 2 degrees C in hypertonic solution was about half of that in rat fast twitch muscle; the voltage distribution of the frog charge was similar to rat soleus muscle. 5. Warming between 2 and 15 degrees C had no effect on either the amount of steady-state distribution of charge in mammalian or frog muscles. 6. At 2 degrees C, the kinetics of charge movement in fast and slow twitch mammalian muscles were similar and 2--3 times faster than frog muscle at the same temperature. In fast and slow mammalian fibres at 2 degrees C similar times were taken to shift the same fractions of the total amount of charge. The Q10 of charge movement kinetics was between 1.2 and 2.0 in the three muscles studied.

CARE AND FEEDING OF FROGS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Margaret; Chiang, Eugene, E-mail: mpan@astro.berkeley.edu

2012-01-15

'Propellers' are features in Saturn's A ring associated with moonlets that open partial gaps. They exhibit non-Keplerian motion (Tiscareno et al.); the longitude residuals of the best-observed propeller, 'Bleriot', appear consistent with a sinusoid of period {approx}4 years. Pan and Chiang proposed that propeller moonlets librate in 'frog resonances' with co-orbiting ring material. By analogy with the restricted three-body problem, they treated the co-orbital material as stationary in the rotating frame and neglected non-co-orbital material. Here we use simple numerical experiments to extend the frog model, including feedback due to the gap's motion, and drag associated with the Lindblad diskmore » torques that cause Type I migration. Because the moonlet creates the gap, we expect the gap centroid to track the moonlet, but only after a time delay t{sub delay}, the time for a ring particle to travel from conjunction with the moonlet to the end of the gap. We find that frog librations can persist only if t{sub delay} exceeds the frog libration period P{sub lib}, and if damping from Lindblad torques balances driving from co-orbital torques. If t{sub delay} << Pl{sub ib}, then the libration amplitude damps to zero. In the case of Bleriot, the frog resonance model can reproduce the observed libration period P{sub lib} {approx_equal} 4 yr. However, our simple feedback prescription suggests that Bleriot's t{sub delay} {approx} 0.01P{sub lib}, which is inconsistent with the observed libration amplitude of 260 km. We urge more accurate treatments of feedback to test the assumptions of our toy models.« less

Conserving Prairie Pothole Region wetlands and surrounding grasslands: evaluating effects on amphibians

USGS Publications Warehouse

Mushet, David M.; Neau, Jordan L.

2014-01-01

The maintenance of viable and genetically diverse populations of amphibians in the Prairie Pothole Region of the United States depends on upland as well as wetland over-wintering and landscape level habitat features.Prairie pothole wetlands provide important amphibian breeding habitat while grasslands surrounding these wetlands provide foraging habitat for adults, overwintering habitat for some species, and important connectivity among breeding wetlands.Grasslands surrounding wetlands were found to be especially important for wood frogs and northern leopard frogs, while croplands dominated habitat utilized by Great Plains toads and Woodhouse’s toads.Habitat suitability mapping highlighted (1) the influence of deep-water overwintering wetlands on suitable habitat for four of five anuran species encountered; (2) the lack of overlap between areas of core habitat for both the northern leopard frog and wood frog compared to the core habitat for both toad species; and (3) the importance of conservation programs in providing grassland components of northern leopard frog and wood frog habitat.Currently, there are approximately 7.2 million acres (2.9 million hectares, ha) of habitat in the PPR identified as suitable for amphibians. WRP and CRP wetland and grassland habitats accounted for approximately 1.9 million acres (0.75 million ha) or 26 percent of this total area.Continued loss of amphibian habitat resulting from an ongoing trend of returning PPR conservation lands to crop production, will likely have significant negative effects on the region’s ability to maintain amphibian biodiversity. Conversely, increases in conservation wetlands and surrounding grasslands on the PPR landscape have great potential to positively influence the region’s amphibian populations.