These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Thyroid Histopathology Assessments for the Amphibian Metamorphosis Assay to Detect Thyroid-active Substances  

EPA Science Inventory

In support of an Organization for Economic Cooperation and Development (OECD) Amphibian Metamorphosis Assay (AMA) Test Guideline for the detection of substances that interact with the hypothalamic-pituitary-thyroid axis, a document was developed that provides a standardized appro...

2

Thyroid Hormone-disrupting Effects and the Amphibian Metamorphosis Assay  

PubMed Central

There are continued concerns about endocrine-disrupting chemical effects, and appropriate vertebrate models for assessment of risk are a high priority. Frog tadpoles are very sensitive to environmental substances because of their habitat and the complex processes of metamorphosis regulated by the endocrine system, mainly thyroid hormones. During metamorphosis, marked alteration in hormonal factors occurs, as well as dramatic structural and functional changes in larval tissues. There are a variety of mechanisms determining thyroid hormone balance or disruption directly or indirectly. Direct-acting agents can cause changes in thyroxine synthesis and/or secretion in thyroid through effects on peroxidases, thyroidal iodide uptake, deiodinase, and proteolysis. At the same time, indirect action may result from biochemical processes such as sulfation, deiodination and glucuronidation. Because their potential to disrupt thyroid hormones has been identified as an important consideration for the regulation of chemicals, the OECD and the EPA have each established guidelines that make use of larval African clawed frogs (Xenopus laevis) and frog metamorphosis for screening and testing of potential endocrine disrupters. The guidelines are based on evaluation of alteration in the hypothalamic-pituitary-thyroid axis. One of the primary endpoints is thyroid gland histopathology. Others are mortality, developmental stage, hind limb length, snout-vent length and wet body weight. Regarding histopathological features, the guidelines include core criteria and additional qualitative parameters along with grading. Taking into account the difficulties in evaluating amphibian thyroid glands, which change continuously throughout metamorphosis, histopathological examination has been shown to be a very sensitive approach. PMID:22481853

Miyata, Kaori; Ose, Keiko

2012-01-01

3

Triclosan exposure alters postembryonic development in a Pacific tree frog (Pseudacris regilla) Amphibian Metamorphosis Assay (TREEMA).  

PubMed

The Amphibian Metamorphosis Assay (AMA), developed for Xenopus laevis, is designed to identify chemicals that disrupt thyroid hormone (TH)-mediated biological processes. We adapted the AMA for use on an ecologically-relevant North American species, the Pacific tree frog (Pseudacris regilla), and applied molecular endpoints to evaluate the effects of the antibacterial agent, triclosan (TCS). Premetamorphic (Gosner stage 26-28) tadpoles were immersed for 21 days in solvent control, 1.5 ?g/L thyroxine (T(4)), 0.3, 3 and 30 ?g/L (nominal) TCS, or combined T(4)/TCS treatments. Exposure effects were scored by morphometric (developmental stage, wet weight, and body, snout-vent and hindlimb lengths) and molecular (mRNA abundance using quantitative real time polymerase chain reaction) criteria. T(4) treatment alone accelerated development concomitant with altered levels of TH receptors ? and ?, proliferating cell nuclear antigen, and gelatinase B mRNAs in the brain and tail. We observed TCS-induced perturbations in all of the molecular and morphological endpoints indicating that TCS exposure disrupts coordination of postembryonic tadpole development. Clear alterations in molecular endpoints were evident at day 2 whereas the earliest morphological effects appeared at day 4 and were most evident at day 21. Although TCS alone (3 and 30 ?g/L) was protective against tadpole mortality, this protection was lost in the presence of T(4). The Pacific tree frog is the most sensitive species examined to date displaying disruption of TH-mediated development by a common antimicrobial agent. PMID:23159728

Marlatt, Vicki L; Veldhoen, Nik; Lo, Bonnie P; Bakker, Dannika; Rehaume, Vicki; Vallée, Kurtis; Haberl, Maxine; Shang, Dayue; van Aggelen, Graham C; Skirrow, Rachel C; Elphick, James R; Helbing, Caren C

2013-01-15

4

The phylogeny of amphibian metamorphosis.  

PubMed

Frogs have one of the most extreme metamorphoses among vertebrates. How did this metamorphosis evolve? By combining the methods previously proposed by Mabee and Humphries (1993) and Velhagen (1997), I develop a phylogenetic method suited for rigorous analysis of this question. In a preliminary analysis using 12 transformation sequence characters and 36 associated event sequence characters, all drawn from the osteology of the skull, the evolution of metamorphosis is traced on an assumed phylogeny. This phylogeny has lissamphibians (frogs, salamanders, and caecilians) monophyletic, with frogs the sister group of salamanders. Successive outgroups used are temnospondyls and discosauriscids, both of which are fossil groups for which ontogenetic data are available. In the reconstruction of character evolution, an unambiguous change (synapomorphy) along the branch leading to lissamphibians is a delay in the lengthening of the maxilla until metamorphosis, in accordance with my previous suggestion (Reiss, 1996). However, widening of the interpterygoid vacuity does not appear as a synapomophy of lissamphibians, due to variation in the character states in the outgroups. From a more theoretical perspective, the reconstructed evolution of amphibian metamorphosis involves examples of heterochrony, through the shift of ancestral premetamorphic events to the metamorphic period, caenogenesis, through the origin of new larval features, and terminal addition, through the origin of new adult features. Other changes don't readily fit these categories. This preliminary study provides evidence that metamorphic changes in frogs arose as further modifications of changes unique to lissamphibians, as well as a new method by which such questions can be examined. PMID:16351859

Reiss, John O

2002-01-01

5

Evaluation of the amphibian metamorphosis assay: exposure to the goitrogen methimazole and the endogenous thyroid hormone L-thyroxine.  

PubMed

The U.S. Environmental Protection Agency (U.S. EPA) has included an amphibian metamorphosis assay (AMA) to detect thyroid active chemicals in Tier 1 testing of their endocrine screening program. To understand the variability, specificity, and reliability of the key endpoints of this assay, two exposure studies with Xenopus laevis tadpoles were conducted with two known thyroid-active compounds, namely, methimazole or L-thyroxine, for a total of 21 d. In addition, various increased-flow-rate treatments were included in the exposures to evaluate the effects of physical stress on metamorphic development. The endpoints examined in the exposures were wet weight, snout-vent length, hind-limb length, developmental stage, and thyroid and gonadal histopathology. As expected, the results indicated that both methimazole and L-thyroxine were thyroid active in the AMA, hind-limb length and thyroid histopathology being the most sensitive endpoints of thyroid activity. Tadpoles that were exposed to the various physical stressors in these experiments showed no signs of altered metamorphic development, and exposure to the thyroid-active compounds had no effect on the developing gonad of X. laevis. Taken together, these results support the use of the AMA as a Tier 1 endocrine screen for detection of potential thyroid pathway activity; however, the lack of a true negative response (no-effect) during the validation process prevents a full evaluation of this assay's specificity at this time. PMID:20821516

Coady, Katherine; Marino, Troy; Thomas, Johnson; Currie, Rebecca; Hancock, Gregg; Crofoot, Jackie; McNalley, Lindsay; McFadden, Lisa; Geter, David; Klecka, Gary

2010-04-01

6

The metamorphosis of amphibian toxicogenomics.  

PubMed

Amphibians are important vertebrates in toxicology often representing both aquatic and terrestrial forms within the life history of the same species. Of the thousands of species, only two have substantial genomics resources: the recently published genome of the Pipid, Xenopus (Silurana) tropicalis, and transcript information (and ongoing genome sequencing project) of Xenopus laevis. However, many more species representative of regional ecological niches and life strategies are used in toxicology worldwide. Since Xenopus species diverged from the most populous frog family, the Ranidae, ~200 million years ago, there are notable differences between them and the even more distant Caudates (salamanders) and Caecilians. These differences include genome size, gene composition, and extent of polyploidization. Application of toxicogenomics to amphibians requires the mobilization of resources and expertise to develop de novo sequence assemblies and analysis strategies for a broader range of amphibian species. The present mini-review will present the advances in toxicogenomics as pertains to amphibians with particular emphasis upon the development and use of genomic techniques (inclusive of transcriptomics, proteomics, and metabolomics) and the challenges inherent therein. PMID:22435070

Helbing, Caren C

2012-01-01

7

The Metamorphosis of Amphibian Toxicogenomics  

PubMed Central

Amphibians are important vertebrates in toxicology often representing both aquatic and terrestrial forms within the life history of the same species. Of the thousands of species, only two have substantial genomics resources: the recently published genome of the Pipid, Xenopus (Silurana) tropicalis, and transcript information (and ongoing genome sequencing project) of Xenopus laevis. However, many more species representative of regional ecological niches and life strategies are used in toxicology worldwide. Since Xenopus species diverged from the most populous frog family, the Ranidae, ~200 million years ago, there are notable differences between them and the even more distant Caudates (salamanders) and Caecilians. These differences include genome size, gene composition, and extent of polyploidization. Application of toxicogenomics to amphibians requires the mobilization of resources and expertise to develop de novo sequence assemblies and analysis strategies for a broader range of amphibian species. The present mini-review will present the advances in toxicogenomics as pertains to amphibians with particular emphasis upon the development and use of genomic techniques (inclusive of transcriptomics, proteomics, and metabolomics) and the challenges inherent therein. PMID:22435070

Helbing, Caren C.

2012-01-01

8

Do effects of mercury in larval amphibians persist after metamorphosis?  

E-print Network

Do effects of mercury in larval amphibians persist after metamorphosis? Brian D. Todd · John D the role of environmental contaminants in global amphibian declines, and evidence that post-metamorphic life stages contribute disproportionately to amphibian population dynamics, most studies in amphibian

Todd, Brian

9

Do effects of mercury in larval amphibians persist after metamorphosis?  

E-print Network

Do effects of mercury in larval amphibians persist after metamorphosis? Brian D. Todd · John D in global amphibian declines, and evidence that post-metamorphic life stages contribute disproportionately to amphibian population dynamics, most studies in amphibian ecotoxicology focus on larval life stages. Studies

Hopkins, William A.

10

Effects of freshwater petroleum contamination on amphibian hatching and metamorphosis  

SciTech Connect

This study examined the effects of freshwater petroleum contamination on amphibian reproduction. The primary objectives were to assess the potential environmental and physiological impacts of runoff petroleum products on amphibians, using the green tree frog (Hyla cinerea) as a target species and engine crankcase oil as a contaminant. Egg hatching success, tadpole growth, and successful metamorphosis were measured in four concentrations of oil. The effects of oil on food source was also studied. Hatching success was not measurably influenced by the presence of oil. Tadpole and alga growth were negatively associated with the presence of oil. No tadpoles from the high concentration of oil treatments successfully metamorphosed.

Mahaney, P.A. (Univ. of Georgia, Aiken, SC (United States). Dept. of Zoology)

1994-02-01

11

METAMORPHOSIS OF TWO AMPHIBIAN SPECIES AFTER CHRONIC CADMIUM EXPOSURE IN OUTDOOR AQUATIC MESOCOSMS  

Microsoft Academic Search

Amphibian larvae at contaminated sites may experience an alteration of metamorphic traits and survival compared to amphibians in uncontaminated conditions. Effects of chronic cadmium (Cd) exposure on the metamorphosis of American toads (Bufo americanus) and southern leopard frogs (Rana sphenocephala) were determined. The two species were reared separately from shortly after hatching through metamorphosis in outdoor mesocosms (1,325-L polyethylene cattle

Stacy M. James; Edward E. Little; Raymond D. Semlitsch

2005-01-01

12

Restructuring of the amphibian gut microbiota through metamorphosis.  

PubMed

Vertebrates maintain complex symbioses with a diverse community of microbes residing within their guts. The microbial players in these symbioses differ between major taxa of vertebrates, such that fish and amniotes maintain notably different communities. To date, there has not been a culture-independent inventory of an amphibian gut microbial community. Here, we compared gut microbial communities of tadpoles and frogs of the Northern leopard frog (Lithobates pipiens). We utilized Illumina sequencing, which allowed us to inventory more than 450?000 microbial sequences. We found that tadpoles and frogs differ markedly in the composition of their gut microbial communities, with tadpoles maintaining a community more similar to fish, whereas the frog community resembles that of amniotes. Additionally, frogs maintain a community with lower phylogenetic diversity compared with tadpoles. The significant restructuring of the microbiota is likely due to changes in diet as well as the large reorganization of the intestinal organ during metamorphosis. Overall, we propose that amphibians represent an important system in which to study regulation and selection of gut microbial communities. PMID:24249298

Kohl, Kevin D; Cary, Tawnya L; Karasov, William H; Dearing, M Denise

2013-12-01

13

Amphibians  

NSDL National Science Digital Library

Amphibians are vertebrates. Amphibians lay eggs to reproduce and undergo metamorphosis to go from offspring to adult. They are cold-blooded, meaning they rely on their surrounding environment and the sun to stay warm.

Olivia Worland (Purdue University;Biological Sciences)

2008-06-11

14

Amphibian Metamorphosis: A Sensitive Life Stage to Chemical and Non-chemical Stressors  

EPA Science Inventory

Amphibian metamorphosis is a dynamic period of post-embryonic development which transforms the larval anuran into the juvenile. The body structure is remodeled through a variety of processes which may be perturbed by exposure to chemicals as well as other environmental stressors....

15

Effects of pesticide exposure and the amphibian chytrid fungus on gray treefrog (Hyla chrysoscelis) metamorphosis.  

PubMed

Pesticides are detectable in most aquatic habitats and have the potential to alter host-pathogen interactions. The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been associated with amphibian declines around the world. However, Bd-associated declines are more prominent in some areas, despite nearly global distribution of Bd, suggesting other factors contribute to disease outbreaks. In a laboratory study, the authors examined the effects of 6 different isolates of Bd in the presence or absence of a pesticide (the insecticide carbaryl or the fungicide copper sulfate) to recently hatched Cope's gray treefrog (Hyla chrysoscelis) tadpoles reared through metamorphosis. The authors found the presence or absence of pesticides differentially altered the mass at metamorphosis of tadpoles exposed to different Bd isolates, suggesting that isolate could influence metamorphosis but not in ways expected based on origin of the isolate. Pesticide exposure had the strongest impact on metamorphosis of all treatment combinations. Whereas copper sulfate exposure reduced the length of the larval period, carbaryl exposure had apparent positive effects by increasing mass at metamorphosis and lengthening larval period, which adds to evidence that carbaryl can stimulate development in counterintuitive ways. The present study provides limited support to the hypothesis that pesticides can alter the response of tadpoles to isolates of Bd and that the insecticide carbaryl can alter developmental decisions. PMID:25044296

Gaietto, Kristina M; Rumschlag, Samantha L; Boone, Michelle D

2014-10-01

16

Metamorphosis  

NSDL National Science Digital Library

This illustrated guide is designed to help students understand and learn the difference between simple and complete metamorphosis. The Web page, which can be easily printed for use at field sites, illustrates: complete metamorphosis for lepidoptera (butterflies and moths), simple metamorphosis for thysanura (silverfish) and simple metamorphosis for heteroptera (true bugs.)

17

The evolution of amphibian metamorphosis: insights based on the transformation of the aortic arches of Pelobates fuscus (Anura)  

Microsoft Academic Search

In order to gain insights into how the aortic arches changed during the transition of vertebrates to land, trans- formations of the aortic arches during the metamorphosis of Pelobates fuscus were investigated and compared with data from the early development of a recent ganoid fish Amia calva and a primitive caudate amphibian Salamandrella keyserlingi . Although in larval Pelobates ,

Hana Kolesová; Alois Lametschwandtner; Zbyn?k Ro?ek

2007-01-01

18

Suitability of golf course ponds for amphibian metamorphosis when bullfrogs are removed.  

PubMed

Managing areas designed for human recreation so that they are compatible with natural amphibian populations can reduce the negative impacts of habitat destruction. We examined the potential for amphibians to complete larval development in golf course ponds in the presence or absence of overwintered bullfrog tadpoles (Rana catesbeiana), which are frequently found in permanent, human-made ponds. We reared larval American toads (Bufo americanus), southern leopard frogs (R. sphenocephala), and spotted salamanders (Ambystoma maculatum) with 0 or 5 overwintered bullfrog tadpoles in field enclosures located in ponds on golf courses or in experimental wetlands at a reference site. Survival to metamorphosis of American toads, southern leopard frogs, and spotted salamanders was greater in ponds on golf courses than at reference sites. We attributed this increased survival to low abundance of insect predators in golf course ponds. The presence of overwintered bullfrogs, however, reduced the survival of American toads, southern leopard frogs, and spotted salamanders reared in golf course ponds, indicating that the suitability of the aquatic habitats for these species partly depended on the biotic community present. Our results suggest that ponds in human recreational areas should be managed by maintaining intermediate hydroperiods, which will reduce the presence of bullfrog tadpoles and predators, such as fish, and which may allow native amphibian assemblages to flourish. PMID:18254862

Boone, Michelle D; Semlitsch, Raymond D; Mosby, Cory

2008-02-01

19

Transition of Chytrid Fungus Infection from Mouthparts to Hind Limbs During Amphibian Metamorphosis.  

PubMed

The chytrid fungus, Batrachochytrium dendrobatidis (Bd), is implicated in worldwide amphibian declines. Bd has been shown to qualitatively transition from the mouthparts of tadpoles to the hindlimbs during metamorphosis, but we lack evidence of consistency in the timing of this transition across amphibian species. We also do not have predictive functions for the abundance of Bd in mouthparts and limbs as tadpoles develop or for the relationship between keratin and Bd abundance. Hence, researchers presently have little guidance on where to sample developing amphibians to maximize Bd detection, which could affect the accuracy of prevalence and abundance estimates for this deadly pathogen. Here, we show consistency in the timing of the transition of Bd from mouthparts to hind limbs across two frog species (Osteopilus septentrionalis and Mixophyes fasciolatus). Keratin and Bd simultaneously declined from the mouthparts starting at approximately Gosner stage 40. However, keratin on the hindlimbs began to appear at approximately stage 38 but, on average, Bd was not detectable on the hindlimbs until approximately stage 40, suggesting a lag between keratin and Bd arrival. Predictive functions for the relationships between developmental stage and keratin and developmental stage and Bd for mouthparts and hind limbs are provided so that researchers can optimize sampling designs and minimize erroneous conclusions associated with missing Bd infections or misestimating Bd abundance. PMID:25384612

McMahon, Taegan A; Rohr, Jason R

2014-11-11

20

A DNA-BASED ASSAY IDENTIFIES BATRACHOCHYTRIUM DENDROBATIDIS IN AMPHIBIANS  

Microsoft Academic Search

Chytridiomycosis caused by Batrachochytrium dendrobatidis (Chytridiomycota) has been implicated in declines of amphibian populations on four continents. We have developed a sensitive and specific polymerase chain reaction-based assay to detect this pathogen. We isolated B. dendrobatidis from captive and wild amphibians collected across North America and se- quenced the internal transcribed spacer regions of the rDNA cassette of multiple isolates.

Seanna L. Annis; Farahad P. Dastoor; Heather Ziel; Peter Daszak; Joyce E. Longcore

2004-01-01

21

Dietary selenomethionine exposure induces physical malformations and decreases growth and survival to metamorphosis in an amphibian (Hyla chrysoscelis).  

PubMed

Selenium (Se) is an essential micronutrient with a narrow therapeutic concentration range. The relative toxicity of Se increases as it is biotransformed into organic compounds, primarily selenomethionine (SeMet), within the aquatic food chain. Effects of aquatic Se contamination are well quantified for many freshwater fish and aquatic bird species, but impacts on amphibians are not well known. This study investigated the responses of larval Cope's gray tree frogs (Hyla chrysoscelis) fed a diet enriched with one of two concentrations of SeMet (50.1 and 489.9 ?g Se g(-1) dw [low and high groups, respectively]) by way of a food-limited (ration) or ad libitum (ad lib) feeding regimen. The high dose caused 100 % mortality during the larval period independent of resource provision levels. Regardless of feeding regimen, the low dose decreased larval survival and successful metamorphosis relative to control treatments. The low dose also induced rear limb deformities in ?73 % of individuals initiating metamorphosis. Providing low-dose food by way of a rationed feeding regimen decreased observed toxicity, likely because of decreased dietary exposure to SeMet relative to the low ad lib treatment. Individuals from the low ration treatment had decreased wet mass at initiation and completion of metamorphic climax (Gosner stages 42 through 46) compared with those from the control ad lib treatment, indicating that resource limitation combined with Se exposure might negatively affect energy stores after metamorphosis. However, lipid content analyses of recently metamorphosed individuals did not reveal any influence of treatment or resource provision on energy stored as lipids. The mean tissue Se concentration of individuals that received the low dose and completed metamorphosis was significantly greater than that of control ad lib or ration individuals at the same developmental stage. This study demonstrates that larval exposure to dietary SeMet can decrease growth and survival and induce deformities in a developing amphibian. Furthermore, retention of Se body burdens through metamorphosis suggests that surviving individuals can transport Se accumulated from contaminated aquatic environments into terrestrial food webs. PMID:23229196

Lockard, Laura; Rowe, Christopher L; Heyes, Andrew

2013-04-01

22

Transition of Chytrid Fungus Infection from Mouthparts to Hind Limbs During Amphibian Metamorphosis  

E-print Network

Abstract: The chytrid fungus, Batrachochytrium dendrobatidis (Bd), is implicated in worldwide amphibian infections or misestimating Bd abundance. Keywords: Batrachochytrium dendrobatidis, amphibian decline, chytridiomycosis, quantitative PCR The pathogenic chytrid fungus, Batrachochytrium dendro- batidis (Bd

Lajeunesse, Marc J.

23

DEVELOPMENT OF AN AMPHIBIAN METAMORPHOSIS MODEL FOR DETECTING THYROID AXIS DISRUPTION  

EPA Science Inventory

Metamorphosis in Xenopus laevis represents an elaborate process of post-embryonic development which is thyroid hormone (TH) dependent. The development of a functional thyroid axis and the responses of tissues to different TH concentrations are well defined in this species, provid...

24

Metamorphosis Matching  

NSDL National Science Digital Library

This is an activity where learners will compare the different metamorphosis stages of amphibians. By matching different life stages of different species, the learners can compare and contrast key characteristics and stages of the life cycle. Learners will match larval stages to adult stages and notice bodily changes in the growth process. This activity can be modified for a slightly more advanced topic.

Aquariums, Association O.

2009-01-01

25

The development of the adult intestinal stem cells: Insights from studies on thyroid hormone-dependent amphibian metamorphosis  

PubMed Central

Adult organ-specific stem cells are essential for organ homeostasis and repair in adult vertebrates. The intestine is one of the best-studied organs in this regard. The intestinal epithelium undergoes constant self-renewal throughout adult life across vertebrates through the proliferation and subsequent differentiation of the adult stem cells. This self-renewal system is established late during development, around birth, in mammals when endogenous thyroid hormone (T3) levels are high. Amphibian metamorphosis resembles mammalian postembryonic development around birth and is totally dependent upon the presence of high levels of T3. During this process, the tadpole intestine, predominantly a monolayer of larval epithelial cells, undergoes drastic transformation. The larval epithelial cells undergo apoptosis and concurrently, adult epithelial stem/progenitor cells develop de novo, rapidly proliferate, and then differentiate to establish a trough-crest axis of the epithelial fold, resembling the crypt-villus axis in the adult mammalian intestine. We and others have studied the T3-dependent remodeling of the intestine in Xenopus laevis. Here we will highlight some of the recent findings on the origin of the adult intestinal stem cells. We will discuss observations suggesting that liganded T3 receptor (TR) regulates cell autonomous formation of adult intestinal progenitor cells and that T3 action in the connective tissue is important for the establishment of the stem cell niche. We will further review evidence suggesting similar T3-dependent formation of adult intestinal stem cells in other vertebrates. PMID:21896185

2011-01-01

26

Amphibians.  

ERIC Educational Resources Information Center

Describes some of the characteristics of amphibians. Contains teaching activities ranging from a "frog sing-along" to lessons on amphibian adaptations, and night hikes to identify frog calls. Includes reproducible handouts to be used with the activities, and a quiz. (TW)

Naturescope, 1987

1987-01-01

27

Artificially induced metamorphosis acetone in Acris gryllus  

Microsoft Academic Search

The causative agents (hormones) involved in amphibian metamorphosis as well as the involved specific endocrine organs have been well established for decades. Tri-iodothyronine and thyroxin, both secretions of the larval thyroid gland, are directly responsible for metamorphosis under physiological conditions. High amounts of the element iodine (approximately 300 times the amount found in equally effective levels of thyroxin) can also

Solomon Pollard; James A. Adams

1988-01-01

28

Differential patterns of accumulation and retention of dietary trace elements associated with coal ash during larval development and metamorphosis of an amphibian.  

PubMed

We performed an experiment in which larval gray tree frogs (Hyla chrysoscelis) were raised through metamorphosis on diets increased with a suite of elements associated with coal combustion residues (silver [Ag], arsenic [As], cadmium [Cd], chromium [Cr], copper [Cu], mercury [Hg], lead [Pb], selenium [Se], vanadium [V], and zinc [Zn]) at "low" and "high" concentrations. We quantified accumulation of metals at three life stages (mid-larval development, initiation of metamorphosis, and completion of metamorphosis) as well as effects on survival, metabolic rate, size at metamorphosis, and duration and loss of weight during metamorphosis. Most elements were accumulated in a dose-dependent pattern by some or all life stages, although this was not the case for Hg. For most elements, larval body burdens exceeded those of later life stages in some or all treatments (control, low, or high). However for Se, As, and Hg, body burdens in control and low concentrations were increased in later compared with earlier life stages. A lack of dose-dependent accumulation of Hg suggests that the presence of high concentrations of other elements (possibly Se) either inhibited accumulation or increased depuration of Hg. The duration of metamorphosis (forelimb emergence through tail resorption) was lengthened in individuals exposed to the highest concentrations of elements, but there were no other statistically significant biological effects. This study shows that patterns of accumulation and possibly depuration of metals and trace elements are complex in animals possessing complex life cycles. Further study is required to determine specific interactions affecting these patterns, in particular which elements may be responsible for affecting accumulation or retention of Hg when organisms are exposed to complex mixtures of elements. PMID:24169791

Heyes, Andrew; Rowe, Christopher L; Conrad, Phillip

2014-01-01

29

PROGRESS TOWARDS DEVELOPMENT OF AN AMPHIBIAN-BASED THYROID SCREENING ASSAY USING XENOPUS LAEVIS: ORGANISMAL AND THYROIDAL RESPONSES TO THE MODEL COMPOUNDS 6-PROPYLTHIOURACIL, METHIMAZOLE, AND THYROXINE.  

EPA Science Inventory

The data presented in this manuscript specifically addresses the development and standardization needs associated with an amphibian thyroid axis screening assay. A protocol for an amphibian growth and reproduction test has been requested by the Office of Science Council and Polic...

30

Evolution of Life Cycles in Early Amphibians  

NASA Astrophysics Data System (ADS)

Many modern amphibians have biphasic life cycles with aquatic larvae and terrestrial adults. The central questions are how and when this complicated ontogeny was established, and what is known about the lives of amphibians in the Paleozoic. Fossil evidence has accumulated that sheds light on the life histories of early amphibians, the origin of metamorphosis, and the transition to a fully terrestrial existence. The majority of early amphibians were aquatic or amphibious and underwent only gradual ontogenetic changes. Developmental plasticity played a major role in some taxa but was restricted to minor modification of ontogeny. In the Permo-Carboniferous dissorophoids, a condensation of crucial ontogenetic steps into a short phase (metamorphosis) is observed. It is likely that the origin of both metamorphosis and neoteny falls within these taxa. Fossil evidence also reveals the sequence of evolutionary changes: apparently, the ontogenetic change in feeding, not the transition to a terrestrial existence per se, made a drastic metamorphosis necessary.

Schoch, Rainer R.

2009-05-01

31

Flatfish: an asymmetric perspective on metamorphosis.  

PubMed

The most asymmetrically shaped and behaviorally lateralized of all the vertebrates, the flatfishes are an endless source of fascination to all fortunate enough to study them. Although all vertebrates undergo left-right asymmetric internal organ placement during embryogenesis, flatfish are unusual in that they experience an additional period of postembryonic asymmetric remodeling during metamorphosis, and thus deviate from a bilaterally symmetrical body plan more than other vertebrates. As with amphibian metamorphosis, all the developmental programs of flatfish metamorphosis are ultimately under the control of thyroid hormone. At least one gene pathway involved in embryonic organ lateralization (nodal-lefty-pitx2) is re-expressed in the larval stage during flatfish metamorphosis. Aspects of modern flatfish ontogeny, such as the gradual translocation of one eye to the opposite side of the head and the appearance of key neurocranial elements during metamorphosis, seem to elegantly recapitulate flatfish phylogeny. This chapter highlights the current state of knowledge of the developmental biology of flatfish metamorphosis with emphases on the genetic, morphological, behavioral, and evolutionary origins of flatfish asymmetry. PMID:23347519

Schreiber, Alexander M

2013-01-01

32

THYROID AXIS INHIBITION IN XENOPUS LAEVIS: DEVELOPMENT OF AN AMPHIBIAN-BASED SCREENING ASSAY  

EPA Science Inventory

In response to the initial EDSTAC recommendations, research was conducted on the development of a Xenopus laevis based tail resorption assay for evaluating thyroid axis disruption. These experiments highlighted key limitations associated with relying on tail resorption as a measu...

33

Establishment of transactivation assay systems using fish, amphibian, reptilian and human thyroid hormone receptors.  

PubMed

Thyroid hormones are essential for the regulation of a wide range of biological processes associated with normal development and metabolism in vertebrates. For the screening of chemicals with a potential thyroid hormone and anti-thyroid hormone activities, we have established transient transactivation assay systems using thyroid hormone receptors (TR? and TR?) from three frog species (Xenopus laevis, Silurana tropicalis and Rana rugosa), a fish (Oryzias latipes), an alligator (Alligator mississippiensis) and a human (Homo sapiens). In all species examined, similar transcriptional activities were found for triiodothyronine (T3 : 10(-11) M in TR? and 10(-10) M in TR?) and thyroxine (T4 : 10(-9) M in TR? and 10(-8) M in TR?). Analogs of thyroid hormone (3,5,3',-triiodothyroacetic acid and 3,3',5,5'-tetraiodothyroacetic acid) exhibited weaker activity, requiring 10-fold higher concentrations for induction of activity when compared with T3 and T4 . These results provide support for the usefulness of in vitro screening assay systems as part of an approach to test chemicals for potential thyroid hormone receptor activity. In addition, we observed that T3 -stimulated transcriptional activity of the O. latipes TR? was inhibited by 10(-5) M tetrabromobisphenol A (TBBPA). In contrast, TR antagonist activities on TR? were not encountered in other species, even with TBBPA concentrations at 10(-5) M. In vitro transactivation assay systems using TRs from various species can be used for the screening of chemicals with thyroid-receptor agonist and antagonist activities. They also can be used for studies that examine evolutionary differences among species in the potency of TR activation. PMID:23112079

Oka, Tomohiro; Mitsui-Watanabe, Naoko; Tatarazako, Norihisa; Onishi, Yuta; Katsu, Yoshinao; Miyagawa, Shinichi; Ogino, Yukiko; Yatsu, Ryohei; Kohno, Satomi; Takase, Minoru; Kawashima, Yukio; Ohta, Yasuhiko; Aoki, Yasunobu; Guillette, Louis J; Iguchi, Taisen

2013-09-01

34

Sodium arsenite induced changes in survival, growth, metamorphosis and genotoxicity in the Indian cricket frog (Rana limnocharis).  

PubMed

Arsenic contamination of the environment is a matter of great concern. Understanding the effects of arsenic on aquatic life will act as biological early warning system to assess how arsenic could shape the biodiversity in the affected areas. Rapid decline in amphibian population in recent decades is a cause of major concern. Over the years, amphibians have been recognized as excellent bio-indicators of environmental related stress. In the present study, we examined the toxic and genotoxic effects of sodium arsenite in the tadpoles of the Indian cricket frog (Rana limnocharis). Sodium arsenite at different concentrations (0, 50, 100, 200 and 400 ?g L(-1)) neither induced lethality nor significantly altered body weight at metamorphosis. However, it accelerated the rate of metamorphosis at higher concentrations, reduced body size (snout-vent length) and induced developmental deformities such as loss of limbs. Besides, at concentration ranges between 100 and 400 ?g L(-1), sodium arsenite induced statistically significant genotoxicity at 24, 48, 72 and 96 h of the exposure in a concentration-dependent manner. However, it did not show time effects as the highest frequency was found between 48 and 72 h which remained steady subsequently. The genotoxicity was confirmed by comet assay in the whole blood cells. These findings suggest that arsenic at environmentally relevant concentrations has significant sub-lethal effects on R.limnocharis, which may have long-term fitness consequence to the species and may have similar implications in other aquatic life too. PMID:25048924

Singha, Utsab; Pandey, Neelam; Boro, Freeman; Giri, Sarbani; Giri, Anirudha; Biswas, Somava

2014-10-01

35

ELASTICITY ANALYSIS OF AMPHIBIAN LIFE HISTORIES  

EPA Science Inventory

By comparing life history parameters (e.g., age at metamorphosis, age at sexual maturation, egg number, longevity) and phenology of different species, we gain valuable insight into why growth rates differ across populations. Although the demography of most amphibians is lacking, ...

36

DETECTING THYROID COMPOUNDS USING AN ANURAN METAMORPHOSIS MODEL  

EPA Science Inventory

The Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC) recommended in its final report to EPA that an amphibian tail resorption assay be implemented as a Tier 1 screening assay......

37

Bubbles of Metamorphosis  

NASA Astrophysics Data System (ADS)

Metamorphosis presents a puzzling challenge where, triggered by a signal, an organism abruptly transforms its entire shape and form. Here I describe the role of physical fluid dynamic processes during pupal metamorphosis in flies. During early stages of pupation of third instar larvae into adult flies, a physical gas bubble nucleates at a precise temporal and spatial location, as part of the normal developmental program in Diptera. Although its existence has been known for the last 100 years, the origin and control of this ``cavitation'' event has remained completely mysterious. Where does the driving negative pressure for bubble nucleation come from? How is the location of the bubble nucleation site encoded in the pupae? How do molecular processes control such a physical event? What is the role of this bubble during development? Via developing in-vivo imaging techniques, direct bio-physical measurements in live insect pupal structures and physical modeling, here I elucidate the physical mechanism for appearance and disappearance of this bubble and predict the site of nucleation and its exact timing. This new physical insight into the process of metamorphosis also allows us to understand the inherent design of pupal shell architectures in various species of insects.

Prakash, Manu

2011-11-01

38

Ontogenetic loss of phenotypic plasticity of age at metamorphosis in tadpoles  

SciTech Connect

Amphibian larvae exhibit phenotypic plasticity in size at metamorphosis and duration of the larval period. I used Pseudacris crucifer tadpoles to test two models for predicting tadpole age and size at metamorphosis under changing environmental conditions. The Wilbur-Collins model states that metamorphosis is initiated as a function of a tadpole's size and relative growth rate, and predicts that changes in growth rate throughout the larval period affect age and size at metamorphosis. An alternative model, the fixed-rate model, states that age at metamorphosis is fixed early in larval life, and subsequent changes in growth rate will have no effect on the length of the larval period. My results confirm that food supplies affect both age and size at metamorphosis, but developmental rates became fixed at approximately Gosner (1960) stages 35-37. Neither model completely predicted these results. I suggest that the generally accepted Wilbur-Collins model is improved by incorporating a point of fixed developmental timing. Growth trajectories predicted from this modified model fit the results of this study better than trajectories based on either of the original models. The results of this study suggests a constraint that limits the simultaneous optimization of age and size at metamorphosis. 32 refs., 5 figs., 1 tab.

Hensley, F.R. (Univ. of Florida, Gainesville, FL (United States))

1993-12-01

39

Amphibian Skin  

NSDL National Science Digital Library

In this activity, learners explore the concept of permeability to better understand why amphibians are extremely sensitive to pollution. Learners soak one regular hard-boiled egg and one peeled hard-boiled egg in dyed water and then record how the eggs' circumference and appearance change after 24 hours. Learners investigate how the peeled egg represents amphibian skin and how amphibians are affected by pollution.

Aquarium, Omaha'S H.

2009-01-01

40

Monitoring Amphibians  

NSDL National Science Digital Library

In this field study, learners discover how to collect data in the field and how their efforts can help certain animals, specifically, amphibians. The field study allows learners to go into the field, collect data, and share it on Omaha's Henry Doorly Zoo Amphibian Database.

Aquarium, Omaha'S H.

2011-01-01

41

THYROID AXIS INHIBITION IN XENOPUS LAEVIS: DEVELOPMENT OF AN AMPHIBIAN-BASED SCREENING ASSAY FOR THYROID DISRUPTION  

EPA Science Inventory

In response to the initial EDSTAC recommendations, research was conducted on the development of a Xenopus laevis based tail resorption assay for evaluating thyroid axis disruption. These experiments highlighted key limitations associated with reliance on tail resorption as a meas...

42

Effects of the amphibian chytrid fungus and four insecticides on Pacific treefrogs (Pseudacris regilla)  

USGS Publications Warehouse

Chemical contamination may influence host-pathogen interactions, which has implications for amphibian population declines. We examined the effects of four insecticides alone or as a mixture on development and metamorphosis of Pacific Treefrogs (Pseudacris regilla) in the presence or absence of the amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]). Bd exposure had a negative impact on tadpole activity, survival to metamorphosis, time to metamorphosis, and time of tail absorption (with a marginally negative effect on mass at metamorphosis); however, no individuals tested positive for Bd at metamorphosis. The presence of sublethal concentrations of insecticides alone or in a mixture did not impact Pacific Treefrog activity as tadpoles, survival to metamorphosis, or time and size to metamorphosis. Insecticide exposure did not influence the effect of Bd exposure. Our study did not support our prediction that effects of Bd would be greater in the presence of expected environmental concentrations of insecticide(s), but it did show that Bd had negative effects on responses at metamorphosis that could reduce the quality of juveniles recruited into the population.

Kleinhez, Peter; Boone, Michelle D.; Fellers, Gary

2012-01-01

43

Effects of an insecticide on amphibians in large-scale experimental ponds  

USGS Publications Warehouse

We examined the effects of the insecticide carbaryl on larval amphibian communities in large-scale experimental ponds. Tadpoles of two anurans, Woodhouse's toad (Bufo woodhousii) and southern leopard Frog (Rana sphenocephala), were reared in ponds (800 m3 volume) to determine the effects of tadpole density and carbaryl exposure on mass at metamorphosis and on time and survival to metamorphosis. Exposure to carbaryl significantly affected toads at metamorphosis, but not leopard frogs. Carbaryl exposure nearly doubled toad survival compared to controls; this effect may be attributable to an indirect effect of earbaryl increasing algal food resources. The competitive environment (i.e., density) and carbaryl exposure significantly affected the trade-off between mass and time to metamorphosis for toads. Our study is the first to demonstrate that in pond communities where predation and competition may be strong, short-lived insecticides can significantly alter the community dynamics of amphibians.

Boone, M.D.; Semlitsch, R.D.; Fairchild, J.F.; Rothermel, B.B.

2004-01-01

44

Amphibian parathyroids: morphological and functional aspects.  

PubMed

Amphibians living partially or totally in a terrestrial environment are the first tetrapods to possess parathyroid glands. Purely aquatic amphibians and amphibian larvae lack these endocrine glands. The parathyroids develop at the time of metamorphosis. The parathyroid glands in caecilians consist of a single cell type, that of urodeles may be composed of basal (supporting) cells and suprabasal (chief) cells, and that of anurans of small and large chief cells. Parathyroid glands of caecilians and anurans lack connective tissue, blood vessels, and nerves. The parathyroid cells become activated in response to decreased blood calcium concentration and undergo changes indicating increased parathyroid hormone secretion. Increased blood calcium concentration suppresses secretory activity. Usually, parathyroidectomy elicits hypocalcemia in most amphibians. Such operations have no effect in lower urodeles. Parathyroid hormone administration provokes hypercalcemia in most amphibians. The parathyroids of caecilians have not been studied in detail. The urodeles and anurans exhibit seasonal changes in the parathyroid glands. These changes may be initiated by environmental stimuli such as light, temperature, or alterations in blood calcium levels caused by natural hibernation. PMID:8580512

Srivastav, A K; Das, V K; Das, S; Sasayama, Y; Suzuki, N

1995-10-01

45

Inhibition of coral fertilisation and larval metamorphosis by tributyltin and copper.  

PubMed

Fertilisation and larval metamorphosis of reef-building corals are important life history events leading to recruitment of juvenile corals to reef populations. Little is known of the sensitivity of these early life phases to pollution, or their relative susceptibility to certain toxicants compared with established coral colonies. Inhibition of fertilisation and larval metamorphosis of the coral Acropora millepora (Ehrenberg, 1834) was assessed in response to solutions of the antifoulants tributyltin (TBT) and copper (Cu) using laboratory-based bioassays. Nominal concentrations that inhibited 50% fertilisation and metamorphosis (IC50) were calculated from 4 h fertilisation and 24 h metamorphosis assays and were based on introduced dose. Cu was most potent towards fertilisation with an IC50 of 17.4 micrograms/l. TBT however, proved more toxic to larval metamorphosis having an IC50 of 2.0 micrograms/l. Inert surfaces coated with either Cu- or TBT-based antifouling paint also inhibited fertilisation and metamorphosis. The degree of inhibition was correlated with surface area of the paint coating. These results indicate fertilisation and metamorphosis of coral can be sensitive to active components of antifouling paints. PMID:11125701

Negri, A P; Heyward, A J

2001-02-01

46

Reptiles, Amphibians, and Salmonella  

MedlinePLUS

... Submit What's this? Submit Button CDC Features Reptiles, Amphibians, and Salmonella Language: English Español (Spanish) Share Compartir ... do people get Salmonella infections from reptiles and amphibians? Reptiles and amphibians might have Salmonella germs on ...

47

Architecture and Metamorphosis  

PubMed Central

When compared to other conserved housekeeping protein families, such as ribosomal proteins, during the evolution of higher eukaryotes, aminoacyl-tRNA synthetases (aaRSs) show an apparent high propensity to add new sequences, and especially, new domains. The stepwise emergence of those new domains is consistent with their involvement in a broad range of biological functions beyond protein synthesis, and correlates with the increasing biological complexity of higher organisms. The new domains have been extensively characterized based on their evolutionary origins and their sequence, structural and functional features. While some of the domains are uniquely found in aaRSs and may have originated from nucleic acid binding motifs, others are common domain modules mediating protein-protein interactions that play a critical role in the assembly of the multi-synthetase complex (MSC). Interestingly, the MSC has emerged from a miniature complex in yeast, to a large, stable complex in insects to humans. The human MSC consists of 9 aaRSs (LysRS, ArgRS, GlnRS, AspRS, MetRS, IleRS, LeuRS and GluProRS) and 3 scaffold proteins (AIMP1/p43, AIMP2/p38 and AIMP3/p18), and has a molecular weight of 1.5 million Da. The MSC has been proposed to have a functional dualism: both facilitating protein synthesis and serving as a reservoir of non-canonical functions associated with its synthetase and non-synthetase components. Importantly, domain additions and functional expansions are not limited to the components of the MSC and are found in almost all aaRS proteins. From a structural perspective, multi-functionalities are represented by multiple conformational states. In fact, alternative conformations of aaRSs have been generated by various mechanisms from proteolysis to alternative splicing and posttranslational modifications, as well as by disease-causing mutations. Therefore, the metamorphosis between different conformational states is connected to the activation and regulation of the novel functions of aaRSs in higher eukaryotes. PMID:23536245

2013-01-01

48

Differences in susceptibility of various life stages of amphibians to pesticide exposure  

Microsoft Academic Search

Pesticide exposure is discussed as one of the adverse factor that causes impairment of amphibian larval development. Susceptibility of tadpoles to pesticide exposure differs depending on the developmental stages at which individuals are contaminated.This study focused on the influence of the pyrethroid insecticide cypermethrin on the hatching success, mortality and deformities in further development, duration of metamorphosis, and growth of

Kerstin Greulich; Stephan Pflugmacher

2003-01-01

49

Amphibian Bioacoustics  

NASA Astrophysics Data System (ADS)

Anuran amphibians (frogs and toads) of most of the 3,500 species that exist today are highly vocal animals. In most frogs, males will spend considerable energy on calling and incur sizeable predation risks and the females’ detection and localization of the calls of conspecific males is often a prerequisite for successful mating. Therefore, acoustic communication is evidently evolutionarily important in the anurans, and their auditory system is probably shaped by the selective pressures associated with production, detection and localization of the communication calls.

Christensen-Dalsgaard, Jakob

50

Metamorphosis in a frog that does not have a tadpole.  

PubMed

The evolutionary removal of the tadpole from the frog life history is a very successful strategy, particularly in the tropics. These direct developers form limbs and a frog-like head early in embryogenesis, and they have reduced or lost tadpole-specific structures, like gills, a long, coiled intestine, and tadpole teeth and jaws. Despite the apparently continuous development to the frog morphology, the direct developer, Eleutherodactylus coqui, undergoes a cryptic metamorphosis requiring thyroid hormone. As in Xenopus laevis, there is a stimulation by corticotrophin-releasing factor (CRF) and an upregulation of thyroid hormone receptor ? (thrb). In addition to changes in skin and muscle, thyroid hormone stimulates yolk utilization for froglet growth from a novel tissue, the nutritional endoderm. The activities of CRF and corticosterone (CORT) in metamorphosis may provide the basis for the multiple evolutionary origins of direct development in anuran amphibians. Potential roles for maternally supplied thyroid hormone and its receptor and for deiodinases in regulating tissue sensitivity to thyroid hormone should be the subjects of future investigations. PMID:23347522

Elinson, Richard P

2013-01-01

51

Compromised metamorphosis and thyroid hormone changes in wood frogs (Lithobates sylvaticus) raised on reclaimed wetlands on the Athabasca oil sands.  

PubMed

The wet landscape approach to oil sands tailings reclamation in the Athabasca Oil Sands region involves creating wetlands from fluid tailings in mined-out pits. We measured time to metamorphosis, thyroid hormone status, and detoxification enzyme (EROD) induction in Wood frog (Lithobates sylvaticus) tadpoles raised on reclaimed oil sands wetlands of different ages [young (? 7 yr) vs. old (> 7 yr)] and compared data with tadpoles raised on reference (control) wetlands. Metamorphosis was delayed or never occurred in tadpoles raised in young tailings; those exposed to older tailings developed similarly to those in reference wetlands. Thyroid hormone disruption likely played an important role in the metamorphosis delay as the T3:T4 ratio was lowest in tadpoles raised in young, tailings-affected wetlands. Our findings suggest tailings wetlands become less toxic with age, and that these amphibians will be able to complete their life cycle in tailing wetlands that have sufficiently detoxified with age. PMID:21036440

Hersikorn, Blair D; Smits, Judit E G

2011-02-01

52

A role for Taiman in insect metamorphosis.  

PubMed

Recent studies in vitro have reported that the Methoprene-tolerant (Met) and Taiman (Tai) complex is the functional receptor of juvenile hormone (JH). Experiments in vivo of Met depletion have confirmed this factor's role in JH signal transduction, however, there is no equivalent data regarding Tai because its depletion in larval or nymphal stages of the beetle Tribolium castaneum and the bug Pyrrhocoris apterus results in 100% mortality. We have discovered that the cockroach Blattella germanica possesses four Tai isoforms resulting from the combination of two indels in the C-terminal region of the sequence. The presence of one equivalent indel-1 in Tai sequences in T. castaneum and other species suggests that Tai isoforms may be common in insects. Concomitant depletion of all four Tai isoforms in B. germanica resulted in 100% mortality, but when only the insertion 1 (IN-1) isoforms were depleted, mortality was significantly reduced and about half of the specimens experienced precocious adult development. This shows that Tai isoforms containing IN-1 are involved in transducing the JH signal that represses metamorphosis. Reporter assays indicated that both T. castaneum Tai isoforms, one that contains the IN-1 and another that does not (DEL-1) activated a JH response element (kJHRE) in Krüppel homolog 1 in conjunction with Met and JH. The results indicate that Tai is involved in the molecular mechanisms that repress metamorphosis, at least in B. germanica, and highlight the importance of distinguishing Tai isoforms when studying the functions of this transcription factor in development and other processes. PMID:25356827

Lozano, Jesus; Kayukawa, Takumi; Shinoda, Tetsuro; Belles, Xavier

2014-10-01

53

A Role for Taiman in Insect Metamorphosis  

PubMed Central

Recent studies in vitro have reported that the Methoprene-tolerant (Met) and Taiman (Tai) complex is the functional receptor of juvenile hormone (JH). Experiments in vivo of Met depletion have confirmed this factor's role in JH signal transduction, however, there is no equivalent data regarding Tai because its depletion in larval or nymphal stages of the beetle Tribolium castaneum and the bug Pyrrhocoris apterus results in 100% mortality. We have discovered that the cockroach Blattella germanica possesses four Tai isoforms resulting from the combination of two indels in the C-terminal region of the sequence. The presence of one equivalent indel-1 in Tai sequences in T. castaneum and other species suggests that Tai isoforms may be common in insects. Concomitant depletion of all four Tai isoforms in B. germanica resulted in 100% mortality, but when only the insertion 1 (IN-1) isoforms were depleted, mortality was significantly reduced and about half of the specimens experienced precocious adult development. This shows that Tai isoforms containing IN-1 are involved in transducing the JH signal that represses metamorphosis. Reporter assays indicated that both T. castaneum Tai isoforms, one that contains the IN-1 and another that does not (DEL-1) activated a JH response element (kJHRE) in Krüppel homolog 1 in conjunction with Met and JH. The results indicate that Tai is involved in the molecular mechanisms that repress metamorphosis, at least in B. germanica, and highlight the importance of distinguishing Tai isoforms when studying the functions of this transcription factor in development and other processes. PMID:25356827

Lozano, Jesus; Kayukawa, Takumi; Shinoda, Tetsuro; Belles, Xavier

2014-01-01

54

Metamorphosis of imaginal discs of Drosophila melanogaster  

Microsoft Academic Search

Imaginal discs ofDrosophila melanogaster larvae, 24–53 hrs after oviposition, were transplanted into mature immobile larval hosts. The transplants did not respond to the hormonal stimuli of metamorphosis, but instead completed their larval development. When reinjected into mature larval hosts, they now differentiated the full set of their presumptive imaginal structures. The process of acquiring competence for metamorphosis appears to be

Géza Mindek

1972-01-01

55

Immunohistochemical localization and biochemical changes in catalase and superoxide dismutase during metamorphosis in the olfactory system of frog Microhyla ornata.  

PubMed

Amphibian metamorphosis is characterized by rapid tissue remodeling and drastic changes in the body structure and function. Like other organs, olfactory system also undergoes a dramatic rearrangement as the animal experiences transition from aquatic to terrestrial habitat. Reactive oxygen species (ROS) are known to play an important role during anuran metamorphosis and role of antioxidant enzymes like catalase and superoxide dismutase (SOD) are believed to play a major role in these processes. Therefore, we hypothesize that antioxidant enzymes in the olfactory system may undergo changes that reflect metamorphic processes. Immunohistochemical study revealed the presence of catalase and SOD in the olfactory receptor neurons and also granular reaction in olfactory epithelium of medial diverticulum during metamorphosis. Catalase and SOD immunoreactivity were seen in the epithelium of lateral diverticulum, vomeronasal organ as metamorphosis proceeds and in the apical lining of olfactory epithelium of adult frog. Biochemical study showed that catalase activity gradually increases in the olfactory system from metamorphic stage 40-46 and adult, while SOD activity decreases from stage 40 to 46 and increases in adult. Thus, the localization and relative levels of catalase and SOD during metamorphosis in the olfactory system suggests that these enzymes may be involved in protection from oxidative damage. PMID:22134050

Gaupale, Tekchand C; Londhe, Jayant; Ghaskadbi, Saroj; Subhedar, N K; Bhargava, Shobha

2012-02-01

56

Impacts of hydroperiod on growth and survival of larval amphibians in temporary ponds of Central Pennsylvania, USA  

Microsoft Academic Search

The effects of variable hydroperiod (three levels) and initial density of amphibians (two levels) on survival, growth rate, and time to and mass at metamorphosis were studied for wood frogs (Rana sylvatica), Jefferson salamanders (Ambystoma jeffersonianum), and spotted salamanders (A. maculatum). Experiments were carried out in 260-1 mesocosms set up outdoors in a forest. These pond simulations were designed to

Christopher L. Rowe; William A. Dunson

1995-01-01

57

Multiple stressors in amphibian communities: effects of chemical contamination, bullfrogs, and fish.  

PubMed

A leading hypothesis of amphibian population declines is that combinations of multiple stressors contribute to declines. We examined the role that chemical contamination, competition, and predation play singly and in combination in aquatic amphibian communities. We exposed larvae of American toads (Bufo americanus), southern leopard frogs (Rana sphenocephala), and spotted salamanders (Ambystoma maculatum) to overwintered bullfrog tadpoles (R. catesbeiana), bluegill sunfish (Lepomis macrochirus), the insecticide carbaryl, and ammonium nitrate fertilizer in 1000-L mesocosms. Most significantly, our study demonstrated that the presence of multiple factors reduced survival of B. americanus and A. maculatum and lengthened larval periods of R. sphenocephala. The presence of bluegill had the largest impact on the community; it eliminated B. americanus and A. maculatum and reduced the abundance of R. sphenocephala. Chemical contaminants had the second strongest effect on the community with the insecticide, reducing A. maculatum abundance by 50% and increasing the mass of anurans (frogs and toads) at metamorphosis; the fertilizer positively influenced time and mass at metamorphosis for both anurans and A. maculatum. Presence of overwintered bullfrogs reduced mass and increased time to metamorphosis of anurans. While both bluegill and overwintered bullfrog tadpoles had negative effects on the amphibian community, they performed better in the presence of one another and in contaminated habitats. Our results indicate that predicting deleterious combinations from single-factor effects may not be straightforward. Our research supports the hypothesis that combinations of factors can negatively impact some amphibian species and could contribute to population declines. PMID:17479852

Boone, Michelle D; Semlitsch, Raymond D; Little, Edward E; Doyle, Meaghan C

2007-01-01

58

Multiple stressors in amphibian communities: Effects of chemical contamination, bullfrogs, and fish  

USGS Publications Warehouse

A leading hypothesis of amphibian population declines is that combinations of multiple stressors contribute to declines. We examined the role that chemical contamination, competition, and predation play singly and in combination in aquatic amphibian communities. We exposed larvae of American toads (Bufo americanus), southern leopard frogs (Rana sphenocephala), and spotted salamanders (Ambystoma maculatum) to overwintered bullfrog tadpoles (R. catesbeiana), bluegill sunfish (Lepomis macrochirus), the insecticide carbaryl, and ammonium nitrate fertilizer in 1000-L mesocosms. Most significantly, our study demonstrated that the presence of multiple factors reduced survival of B. americanus and A. maculatum and lengthened larval periods of R. sphenocephala. The presence of bluegill had the largest impact on the community; it eliminated B. americanus and A. maculatum and reduced the abundance of R. sphenocephala. Chemical contaminants had the second strongest effect on the community with the insecticide, reducing A. maculatum abundance by 50% and increasing the mass of anurans (frogs and toads) at metamorphosis; the fertilizer positively influenced time and mass at metamorphosis for both anurans and A. maculatum. Presence of overwintered bullfrogs reduced mass and increased time to metamorphosis of anurans. While both bluegill and overwintered bullfrog tadpoles had negative effects on the amphibian community, they performed better in the presence of one another and in contaminated habitats. Our results indicate that predicting deleterious combinations from single-factor effects may not be straightforward. Our research supports the hypothesis that combinations of factors can negatively impact some amphibian species and could contribute to population declines. ?? 2007 by the Ecological Society of America.

Boone, M.D.; Semlitsch, R.D.; Little, E.E.; Doyle, M.C.

2007-01-01

59

Acid tolerance in amphibians  

SciTech Connect

Studies of amphibian acid tolerance provide information about the potential effects of acid deposition on amphibian communities. Amphibians as a group appear to be relatively acid tolerant, with many species suffering increased mortality only below pH 4. However, amphibians exhibit much intraspecific variation in acid tolerance, and some species are sensitive to even low levels of acidity. Furthermore, nonlethal effects, including depression of growth rates and increases in developmental abnormalities, can occur at higher pH.

Pierce, B.A.

1985-04-01

60

ELSEVIER Aquaculture 148 (1997) 247-258 Hydrogen peroxide induced metamorphosis of  

E-print Network

ELSEVIER Aquaculture 148 (1997) 247-258 Hydrogen peroxide induced metamorphosis of queen conch, the use of hydrogen peroxide as an alternative to aqueous extracts of the red alga Laurenciu poirei conch to 50 FM hydrogen peroxide for 10 h in both small scale and production scale assays induced full

Boettcher, Anne

61

Amphibian declines, chytridiomycosis  

E-print Network

26/11/08 1 Amphibian declines, chytridiomycosis and climate change Pauline Sanderson EVS4904 ­ Seminar Presentation University of Ottawa November 26th, 2008 Amphibian declines due to · Habitat loss · Fungal disease · Intracellular parasite in the keratin-forming epidermal tissues of amphibians · Targets

Blouin-Demers, Gabriel

62

Interactive effects of competition and predator cues on immune responses of leopard frogs at metamorphosis.  

PubMed

Recent hypotheses suggest that immunosuppression, resulting from altered environmental conditions, may contribute to the increased incidence of amphibian disease around the world. Antimicrobial peptides (AMPs) in amphibian skin are an important innate immune defense against fungal, viral and bacterial pathogens. Their release is tightly coupled with release of the stress hormone noradrenaline (norepinephrine). During metamorphosis, AMPs may constitute the primary immune response in the skin of some species because acquired immune functions are temporarily suppressed in order to prevent autoimmunity against new adult antigens. Suppression of AMPs during this transitional stage may impact disease rates. We exposed leopard frog tadpoles (Lithobates pipiens) to a factorial combination of competitor and caged-predator environments and measured their development, growth and production of hydrophobic skin peptides after metamorphosis. In the absence of predator cues, or if the exposure to predator cues was late in ontogeny, competition caused more than a 250% increase in mass-standardized hydrophobic skin peptides. Predator cues caused a decrease in mass-standardized hydrophobic skin peptides when the exposure was late in ontogeny under low competition, but otherwise had no effect. Liquid chromatography tandem mass spectrometry of the skin peptides showed that they include six AMPs in the brevinin and temporin families and at least three of these peptides are previously uncharacterized. Both of these peptide families have previously been shown to inhibit harmful microbes including Batrachochytrium dendrobatidis, the fungal pathogen associated with global amphibian declines. Our study shows that amphibians may be able to adjust their skin peptide defenses in response to stressors that are experienced early in ontogeny and that these effects extend through an important life-history transition. PMID:24115058

Groner, Maya L; Rollins-Smith, Louise A; Reinert, Laura K; Hempel, John; Bier, Mark E; Relyea, Rick A

2014-02-01

63

Vertebral development and amphibian evolution.  

PubMed

Amphibians provide an unparalleled opportunity to integrate studies of development and evolution through the investigation of the fossil record of larval stages. The pattern of vertebral development in modern frogs strongly resembles that of Paleozoic labyrinthodonts in the great delay in the ossification of the vertebrae, with the centra forming much later than the neural arches. Slow ossification of the trunk vertebrae in frogs and the absence of ossification in the tail facilitate the rapid loss of the tail during metamorphosis, and may reflect retention of the pattern in their specific Paleozoic ancestors. Salamanders and caecilians ossify their centra at a much earlier stage than frogs, which resembles the condition in Paleozoic lepospondyls. The clearly distinct patterns and rates of vertebral development may indicate phylogenetic separation between the ultimate ancestors of frogs and those of salamanders and caecilians within the early radiation of ancestral tetrapods. This divergence may date from the Lower Carboniferous. Comparison with the molecular regulation of vertebral development described in modern mammals and birds suggests that the rapid chondrification of the centra in salamanders relative to that of frogs may result from the earlier migration of sclerotomal cells expressing Pax1 to the area surrounding the notochord. PMID:11324019

Carroll, R L; Kuntz, A; Albright, K

1999-01-01

64

Using Bacterial Extract along with Differential Gene Expression in Acropora millepora Larvae to Decouple the Processes of Attachment and Metamorphosis  

PubMed Central

Biofilms of the bacterium Pseudoalteromonas induce metamorphosis of acroporid coral larvae. The bacterial metabolite tetrabromopyrrole (TBP), isolated from an extract of Pseudoalteromonas sp. associated with the crustose coralline alga (CCA) Neogoniolithon fosliei, induced coral larval metamorphosis (100%) with little or no attachment (0–2%). To better understand the molecular events and mechanisms underpinning the induction of Acropora millepora larval metamorphosis, including cell proliferation, apoptosis, differentiation, migration, adhesion and biomineralisation, two novel coral gene expression assays were implemented. These involved the use of reverse-transcriptase quantitative PCR (RT-qPCR) and employed 47 genes of interest (GOI), selected based on putative roles in the processes of settlement and metamorphosis. Substantial differences in transcriptomic responses of GOI were detected following incubation of A. millepora larvae with a threshold concentration and 10-fold elevated concentration of TBP-containing extracts of Pseudoalteromonas sp. The notable and relatively abrupt changes of the larval body structure during metamorphosis correlated, at the molecular level, with significant differences (p<0.05) in gene expression profiles of 24 GOI, 12 hours post exposure. Fourteen of those GOI also presented differences in expression (p<0.05) following exposure to the threshold concentration of bacterial TBP-containing extract. The specificity of the bacterial TBP-containing extract to induce the metamorphic stage in A. millepora larvae without attachment, using a robust, low cost, accurate, ecologically relevant and highly reproducible RT-qPCR assay, allowed partially decoupling of the transcriptomic processes of attachment and metamorphosis. The bacterial TBP-containing extract provided a unique opportunity to monitor the regulation of genes exclusively involved in the process of metamorphosis, contrasting previous gene expression studies that utilized cues, such as crustose coralline algae, biofilms or with GLW-amide neuropeptides that stimulate the entire onset of larval metamorphosis and attachment. PMID:22655067

Siboni, Nachshon; Abrego, David; Seneca, Francois; Motti, Cherie A.; Andreakis, Nikos; Tebben, Jan; Blackall, Linda L.; Harder, Tilmann

2012-01-01

65

A Qualitative Meta-Analysis Reveals Consistent Effects of Atrazine on Freshwater Fish and Amphibians  

PubMed Central

Objective The biological effects of the herbicide atrazine on freshwater vertebrates are highly controversial. In an effort to resolve the controversy, we conducted a qualitative meta-analysis on the effects of ecologically relevant atrazine concentrations on amphibian and fish survival, behavior, metamorphic traits, infections, and immune, endocrine, and reproductive systems. Data sources We used published, peer-reviewed research and applied strict quality criteria for inclusion of studies in the meta-analysis. Data synthesis We found little evidence that atrazine consistently caused direct mortality of fish or amphibians, but we found evidence that it can have indirect and sublethal effects. The relationship between atrazine concentration and timing of amphibian metamorphosis was regularly nonmonotonic, indicating that atrazine can both accelerate and delay metamorphosis. Atrazine reduced size at or near metamorphosis in 15 of 17 studies and 14 of 14 species. Atrazine elevated amphibian and fish activity in 12 of 13 studies, reduced antipredator behaviors in 6 of 7 studies, and reduced olfactory abilities for fish but not for amphibians. Atrazine was associated with a reduction in 33 of 43 immune function end points and with an increase in 13 of 16 infection end points. Atrazine altered at least one aspect of gonadal morphology in 7 of 10 studies and consistently affected gonadal function, altering spermatogenesis in 2 of 2 studies and sex hormone concentrations in 6 of 7 studies. Atrazine did not affect vitellogenin in 5 studies and increased aromatase in only 1 of 6 studies. Effects of atrazine on fish and amphibian reproductive success, sex ratios, gene frequencies, populations, and communities remain uncertain. Conclusions Although there is much left to learn about the effects of atrazine, we identified several consistent effects of atrazine that must be weighed against any of its benefits and the costs and benefits of alternatives to atrazine use. PMID:20056568

Rohr, Jason R.; McCoy, Krista A.

2010-01-01

66

Where have all the tadpoles gone? Individual genetic tracking of amphibian larvae until adulthood.  

PubMed

Reliably marking larvae and reidentifying them after metamorphosis is a challenge that has hampered studies on recruitment, dispersal, migration and survivorship of amphibians for a long time, as conventional tags are not reliably retained through metamorphosis. Molecular methods allow unique genetic fingerprints to be established for individuals. Although microsatellite markers have successfully been applied in mark-recapture studies on several animal species, they have never been previously used in amphibians to follow individuals across different life cycle stages. Here, we evaluate microsatellites for genetic across-stages mark-recapture studies in amphibians and test the suitability of available software packages for genotype matching. We sampled tadpoles of the dendrobatid frog Allobates femoralis, which we introduced on a river island in the Nature Reserve 'Les Nouragues' in French Guiana. In two subsequent recapture sessions, we searched for surviving juveniles and adults, respectively. All individuals were genotyped at 14 highly variable microsatellite loci, which yielded unique genetic fingerprints for all individuals. We found large differences in the identification success of the programs tested. The pairwise-relatedness-based approach, conducted with the programs kingroup or ML-Relate, performed best with our data set. Matching ventral patterns of juveniles and adult individuals acted as a control for the reliability of the genetic identification. Our results demonstrate that microsatellite markers are a highly powerful tool for studying amphibian populations on an individual basis. The ability to individually track amphibian tadpoles throughout metamorphosis until adulthood will be of substantial value for future studies on amphibian population ecology and evolution. PMID:25388775

Ringler, Eva; Mangione, Rosanna; Ringler, Max

2014-11-12

67

Introducing Environmental Toxicology in Instructional Labs: The Use of a Modified Amphibian Developmental Toxicity Assay to Support Inquiry-Based Student Projects  

ERIC Educational Resources Information Center

Introducing students to the process of scientific inquiry is a major goal of high school and college labs. Environmental toxins are of great concern and public interest. Modifications of a vertebrate developmental toxicity assay using the frog Xenopus laevis can support student-initiated toxicology experiments that are relevant to humans. Teams of…

Sauterer, Roger; Rayburn, James R.

2012-01-01

68

CELL JUNCTIONS IN AMPHIBIAN SKIN  

PubMed Central

Cell junctions have been investigated in the amphibian epidermis, a stratified squamous epithelium, and compared to those described previously in simple columnar epithelia of mammalian cavitary organs. In adult frogs and toads, and in larvae approaching metamorphosis, belts of membrane fusion or zonulae occludentes of considerable depth are regularly found between adjoining cells of the outermost layer of the stratum corneum, binding the cells together into a continuous, uninterrupted sheet. Another set of occluding zonules appears in the second cornified layer (when such a layer is present), and a third set usually occurs in the outermost layer of the stratum granulosum. Specialized elements described as "modified" and "composite" desmosomes are encountered along the lateral and basal aspects, respectively, of the cornified cells; ordinary desmosomes and maculae occludentes (i.e., spots of membrane fusion) are found in all other strata. The usual 200 A intercellular gap is generally maintained between the cells of the stratum germinativum at the basal ends of the intercellular spaces. Hence, the intercellular spaces of the epidermis form a largely continuous network, closed to the external medium and open to the dermal interstitia. The situation is comparable to that found in columnar epithelia, except that the intercellular spaces are much more extensive, and an extracellular subcompartment (or two) apparently exists in the stratum corneum and between the latter and the stratum granulosum. The last subcompartment is usually filled with a dense substance, probably derived from discharged secretory granules. The tripartite junctional complex characteristic of lumen-lining epithelia (i.e., a zonula occludens followed by a zonula adhaerens, and desmosome) is seen only in early larvae; in adults and in larvae approaching metamorphosis, the occluding zonule is followed directly by a series of modified desmosomes. Interpreted in the light of current physiological data, these findings suggest that the diffusion of water, ions, and small, water-soluble molecules is impeded along the intercellular spaces of the epidermis by zonulae occludentes while it is facilitated from cell to cell within the epidermis by zonulae and maculae occludentes. PMID:5859021

Farquhar, Marilyn G.; Palade, George E.

1965-01-01

69

Tadpoles of Early Breeding Amphibians are Negatively Affected by Leaf Litter From Invasive Chinese Tallow Trees  

NASA Astrophysics Data System (ADS)

As wetlands are invaded by Chinese tallow trees (Triadica sebifera), native trees are displaced and detrital inputs to amphibian breeding ponds are altered. I used a mesocosm experiment to examine the effect of Chinese tallow leaf litter on the survival to, size at, and time to metamorphosis of amphibian larvae. Fifty 1000-L cattle watering tanks were treated with 1500 g dry weight of one of five leaf litter treatments: Chinese tallow, laurel oak (Quercus laurifolia), water tupelo (Nyssa aquatica), slash pine (Pinus elliottii), or a 3:1:1:1 mixture. Each tank received 45 tadpoles of Pseudacris feriarum, Bufo terrestris, and Hyla cinerea in sequence according to their natural breeding phonologies. Every Pseudacris feriarum and Bufo terrestris tadpole exposed to Chinese tallow died prior to metamorphosis. Hyla cinerea survival in tanks with tallow-only was significantly lower than that observed for all other leaf treatments. Hyla cinerea tadpoles from tallow-only and mixed-leaf treatments were larger at metamorphosis and transformed faster than those in tanks with native leaves only. These results suggest that Chinese tallow leaf litter may negatively affect tadpoles of early breeding frogs and that Chinese tallow invasion may change the structure of amphibian communities in temporary ponds.

Leonard, N. E.

2005-05-01

70

Growth and developmental effects of coal combustion residues on Southern Leopard Frog (Rana sphenocephala) tadpoles exposed throughout metamorphosis  

SciTech Connect

The effects of aquatic deposition of coal combustion residues (CCRs) on amphibian life histories have been the focus of many recent studies. In summer 2005, we raised larval Southern Leopard Frogs, Rana sphenocephala, on either sand or CCR substrate (approximately 1 cm deep within plastic bins) and documented effects of sediment type on oral disc condition, as well as time to, mass at, and total body length at key developmental stages, including metamorphosis (Gosner stages (GS) 37, 42, and 46). We found no significant difference in mortality between the two treatments and mortality was relatively low (eight of 48 in the control group and four of 48 in the CCR group). Ninety percent of exposed tadpoles displayed oral disc abnormalities, while no control individuals displayed abnormalities. Tadpoles raised on CCR-contaminated sediment had decreased developmental rates and weighed significantly less at all developmental stages, on average, when compared to controls. The CCR treatment group was also significantly shorter In length than controls at the completion of metamorphosis (GS 46). Collectively, these findings are the most severe sub-lethal effects noted for any amphibian exposed to CCRs to date. More research is needed to understand how these long term effects may contribute to the dynamics of local amphibian populations.

Peterson, J.D.; Peterson, V.A.; Mendonca, M.T. [Auburn University, Auburn, AL (United States). Dept. for Biological Science

2008-09-15

71

Fetal adaptations for viviparity in amphibians.  

PubMed

Live-bearing has evolved in all three orders of amphibians-frogs, salamanders, and caecilians. Developing young may be either yolk dependent, or maternal nutrients may be supplied after yolk is resorbed, depending on the species. Among frogs, embryos in two distantly related lineages develop in the skin of the maternal parents' backs; they are born either as advanced larvae or fully metamorphosed froglets, depending on the species. In other frogs, and in salamanders and caecilians, viviparity is intraoviductal; one lineage of salamanders includes species that are yolk dependent and born either as larvae or metamorphs, or that practice cannibalism and are born as metamorphs. Live-bearing caecilians all, so far as is known, exhaust yolk before hatching and mothers provide nutrients during the rest of the relatively long gestation period. The developing young that have maternal nutrition have a number of heterochronic changes, such as precocious development of the feeding apparatus and the gut. Furthermore, several of the fetal adaptations, such as a specialized dentition and a prolonged metamorphosis, are homoplasious and present in members of two or all three of the amphibian orders. At the same time, we know little about the developmental and functional bases for fetal adaptations, and less about the factors that drive their evolution and facilitate their maintenance. J. Morphol., 2014. © 2014 Wiley Periodicals, Inc. PMID:24643944

Wake, Marvalee H

2014-03-19

72

Methods for Evaluating Wetland Condition #12: Using Amphibians in Bioassessments of Wetlands  

USGS Publications Warehouse

Because amphibians have both aquatic and terrestrial life stages they can serve in a unique way among vertebrates as sources of information for bioassessments of both wetlands and surrounding habitats. Although there are many data gaps in our knowledge about the habitat requirements and ecology of many amphibian species, it is apparent that community composition, presence and frequency of abnormalities, various mensural characteristics (e.g. snout vent length divided by body weight) and laboratory diagnostics (e.g. cholinesterase activity, blood chemistry) can be used in developing metrics for an index of biotic integrity. In addition, potential metrics can be derived from the various life stages that most amphibians experience such as egg clusters; embryonic development and hatching rates; tadpole growth, development, and survival; progress and success of metamorphosis; and breeding behavior and presence of adults. It is important, however, to focus on regional biodiversity and species assemblages of amphibians in the development of metrics rather than to strive for broadscale application of common metrics. This report discusses the procedures of developing an index of biotic integrity based on amphibians, explains potential pitfalls in using amphibians in bioassessments, and demonstrates where more research is needed to enhance the use of amphibians in evaluating wetland conditions.

Sparling, D.W.; Richter, K.O.; Calhoun, A.; Micacchion, M.

2001-01-01

73

Understanding of the impact of chemicals on amphibians: a meta-analytic review  

PubMed Central

Many studies have assessed the impact of different pollutants on amphibians across a variety of experimental venues (laboratory, mesocosm, and enclosure conditions). Past reviews, using vote-counting methods, have described pollution as one of the major threats faced by amphibians. However, vote-counting methods lack strong statistical power, do not permit one to determine the magnitudes of effects, and do not compare responses among predefined groups. To address these challenges, we conducted a meta-analysis of experimental studies that measured the effects of different chemical pollutants (nitrogenous and phosphorous compounds, pesticides, road deicers, heavy metals, and other wastewater contaminants) at environmentally relevant concentrations on amphibian survival, mass, time to hatching, time to metamorphosis, and frequency of abnormalities. The overall effect size of pollutant exposure was a medium decrease in amphibian survival and mass and a large increase in abnormality frequency. This translates to a 14.3% decrease in survival, a 7.5% decrease in mass, and a 535% increase in abnormality frequency across all studies. In contrast, we found no overall effect of pollutants on time to hatching and time to metamorphosis. We also found that effect sizes differed among experimental venues and among types of pollutants, but we only detected weak differences among amphibian families. These results suggest that variation in sensitivity to contaminants is generally independent of phylogeny. Some publication bias (i.e., selective reporting) was detected, but only for mass and the interaction effect size among stressors. We conclude that the overall impact of pollution on amphibians is moderately to largely negative. This implies that pollutants at environmentally relevant concentrations pose an important threat to amphibians and may play a role in their present global decline. PMID:22957147

Egea-Serrano, Andrés; Relyea, Rick A; Tejedo, Miguel; Torralva, Mar

2012-01-01

74

Amphibians of Washington  

NSDL National Science Digital Library

This resource on the Amphibians of Washington State has recently been placed online. Created by Brad Moon at the University of Washington at Seattle's Burke Museum of Natural History and Culture (Herpetology Section), the Website features northwestern amphibians. The Website is organized by Order, Family, and Species, with details provided for some species, including a color photograph, written description, and information on Distribution, Habitat, Cool Biology Facts, and Conservation status. Other information accessible via links includes distribution maps, identification keys, phylogenetic information, and online bibliographies. For students and researchers seeking basic information and natural history facts on Washington's amphibians, this resource is a nice reference.

Moon, Brad.

75

What is metamorphosis? C. D. Bishop,*  

E-print Network

, including fungi, flowering plants, and some marine algae. Clearly, the answer depends upon how metamorphosis is an inherently integrative concept, with relevance to developmental biology, ecology, life history evolution a general conception that meta- morphosis represents a transformation of some sort (think caterpillar

Maslakova, Svetlana

76

A conceptual model to facilitate amphibian conservation in the northern Great Plains  

USGS Publications Warehouse

As pressures on agricultural landscapes to meet worldwide resource needs increase, amphibian populations face numerous threats including habitat destruction, chemical contaminants, disease outbreaks, wetland sedimentation, and synergistic effects of these perturbations. To facilitate conservation planning, we developed a conceptual model depicting elements critical for amphibian conservation in the northern Great Plains. First, we linked upland, wetland, and landscape features to specific ecological attributes. Ecological attributes included adult survival; reproduction and survival to metamorphosis; and successful dispersal and recolonization. Second, we linked ecosystem drivers, ecosystem stressors, and ecological effects of the region to each ecological attribute. Lastly, we summarized information on these ecological attributes and the drivers, stressors, and effects that work in concert to influence the maintenance of viable and genetically diverse amphibian populations in the northern Great Plains. While our focus was on the northern Great Plains, our conceptual model can be tailored to other geographic regions and taxa.

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

2012-01-01

77

Effects of depleted uranium on survival, growth, and metamorphosis in the african clawed frog (Xenopus laevis)  

USGS Publications Warehouse

Embryos (stage 8-47, Nieuwkoop and Faber) of the African clawed frog (Xenopus laevis) were subjected to water-borne depleted uranium (DU) concentrations that ranged from 4.8 to 77.7 mg/Lusing an acute 96-h frog embryo teratogenesis assay-Xenopus (FETAX). In a chronic 64-d assay, X. laevis (from embryo through metamorphosis; stages 8-66) were subjected to concentrations of DU that ranged from 6.2 to 54.3 mg/L Our results indicate DU is a non teratogenic metal. No effects on mortality, malformations, or growth were observed in the 96-h FETAX with concentrations of DU that ranged from 4.8 to 77.7 mg/L From stage 8 to stage 47, X. laevis tadpoles do not actively feed and the gills are not well developed. Thus, uptake of DU was reduced despite exposure to elevated concentrations. The 64-d assay resulted in no concentration response for either mortality or malformations; however, a delay in metamorphosis was observed in tadpoles subjected to elevated DU concentrations (from 13.1 to 54.3 mg/L) compared to tadpoles in both the well-water control and reference. The delay in metamorphosis was likely due to increasing body burden of DU that ranged from 0.98 to 2.82 mg/kg. Copyright?? Taylor & Francis Inc.

Mitchell, S.E.; Caldwell, C.A.; Gonzales, G.; Gould, W.R.; Arimoto, R.

2005-01-01

78

Antiviral Immunity in Amphibians  

PubMed Central

Although a variety of virus species can infect amphibians, diseases caused by ranaviruses ([RVs]; Iridoviridae) have become prominent, and are a major concern for biodiversity, agriculture and international trade. The relatively recent and rapid increase in prevalence of RV infections, the wide range of host species infected by RVs, the variability in host resistance among population of the same species and among different developmental stages, all suggest an important involvement of the amphibian immune system. Nevertheless, the roles of the immune system in the etiology of viral diseases in amphibians are still poorly investigated. We review here the current knowledge of antiviral immunity in amphibians, focusing on model species such as the frog Xenopus and the salamander (Ambystoma tigrinum), and on recent progress in generating tools to better understand how host immune defenses control RV infections, pathogenicity, and transmission. PMID:22163335

Chen, Guangchun; Robert, Jacques

2011-01-01

79

AMPHIBIAN POPULATION DYNAMICS  

EPA Science Inventory

Agriculture has contributed to loss of vertebrate biodiversity in many regions, including the U.S. Corn Belt. Amphibian populations, in particular, have experienced widespread and often inexplicable declines, range reductions, and extinctions. However, few attempts have been made...

80

Vikers Viking Amphibian - biplane  

NASA Technical Reports Server (NTRS)

Vikers Viking Amphibian - biplane: Initially procured in 1921 by the U.S. Navy during their studies of foreign designs, the Vickers Viking IV became NACA 17 during its short period of study at Langley.

1924-01-01

81

VERTEBRATES: FISH, AMPHIBIANS, REPTILES, BIRDS, MAMMALS  

E-print Network

VERTEBRATES: FISH, AMPHIBIANS, REPTILES, BIRDS, MAMMALS Contents Amphibians Birds Fish, Characteristics Fish, Populations Fish, Productivity Fish, Systematics and Evolution Mammals Reptiles Amphibians W. Introduction The basic physiology of all amphibians makes these organisms dependent on sources of freshwater

Lowe, Winsor H.

82

Amphibian biology and husbandry.  

PubMed

Extant amphibians comprise three lineages-- salamanders (Urodela or Caudata), frogs and toads (Anura), and caecilians (Gymnophiona, Apoda, or Caecilia)--which contain more than 6,000 species. Fewer than a dozen species of amphibians are commonly maintained in laboratory colonies, and the husbandry requirements for the vast majority of amphibians are poorly known. For these species, a review of basic characteristics of amphibian biology supplemented by inferences drawn from the morphological and physiological characteristics of the species in question provides a basis for decisions about housing and feeding. Amphibians are ectotherms, and their skin is permeable to water, ions, and respiratory gases. Most species are secretive and, in many cases, nocturnal. The essential characteristics of their environment include appropriate levels of humidity, temperature, and lighting as well as retreat sites. Terrestrial and arboreal species require moist substrates, water dishes, and high relative humidity. Because temperature requirements for most species are poorly known, it is advisable to use a temperature mosaic that will allow an animal to find an appropriate temperature within its cage. Photoperiod may affect physiology and behavior (especially reproduction and hibernation), and although the importance of ultraviolet light for calcium metabolism by amphibians is not yet known, ecological observations suggest that it might be important for some species of frogs. Some amphibians are territorial, and some use olfactory cues to mark their territory and to recognize other individuals of their species. All amphibians are carnivorous as adults, and the feeding response of many species is elicited by the movement of prey. Diets should include a mixture of prey species, and it may be advisable to load prey with vitamins and minerals. PMID:17592184

Pough, F Harvey

2007-01-01

83

Shallow End For Amphibians  

NSDL National Science Digital Library

This news brief from Nature magazine summarizes a recent paper discussing the combined effects of climate change on declining amphibian populations. Summer climate (detrimental ultraviolet exposure) appears to be linked to spring disease (lethal fungal infections), placing the future of amphibian populations in jeopardy. Several other interactions may also influence survival, such as predator avoidance (higher in low-water pools), which may in turn lead to increased susceptibility of tadpoles to pesticide poisoning.

2001-01-01

84

Toxicity of two insecticides to California, USA, anurans and its relevance to declining amphibian populations.  

PubMed

Contaminants have been associated with population declines of several amphibian species in California (USA). Pesticides from the Central Valley of California are transported by winds into the Sierra Nevada Mountains and precipitate into wet meadows where amphibians breed. The present study examined the chronic toxicity of two of the insecticides most commonly used in the Central Valley and found in the mountains, chlorpyrifos and endosulfan, to larval Pacific treefrogs (Pseudacris regilla) and foothill yellow-legged frogs (Rana boylii) and discusses the implications of this toxicity to declining amphibian populations. Larvae were exposed to the pesticides from Gosner stages 25 to 26 through metamorphosis. The estimated median lethal concentration (LC50) for chlorpyrifos was 365 microg/L in P. regilla and 66.5 microg/L for R. boylii. Time to metamorphosis increased with concentration of chlorpyrifos in both species, and cholinesterase activity declined with exposure concentration in metamorphs of both species at Gosner stages 42 to 46. For endosulfan, the estimated LC50 was 15.6 microg/L for P. regilla and 0.55 microg/L for R. boylii. All R. boylii exposed to concentrations of greater than 0.8 microg/L died before they entered metamorphosis. Pseudacris regilla remains relatively abundant and is broadly distributed throughout California. In contrast, R. boylii is among the species experiencing severe population declines. The present study adds to the increasing evidence that pesticides are very harmful to amphibians living in areas that are miles from sources of pesticide application. PMID:19290680

Sparling, Donald W; Fellers, Gary M

2009-08-01

85

3D Modelling for Metamorphosis for Animation  

Microsoft Academic Search

In this paper, we propose a novel 3D B-Spline surface reconstruction technique for 3D metamorphosis for animation and entertainment.\\u000a The approach allows one-to-one mapping between the object space and a parameter space, and therefore automatic correspondence\\u000a between a pair of reconstructed objects. B-Spline-based shape representation also has the advantages of: 1) easy shape editing,\\u000a 2) level of detail control, and

Li Bai; Yi Song; Yangsheng Wang

2008-01-01

86

The execution phase of autophagy associated PCD during insect metamorphosis.  

PubMed

During metamorphosis of Manduca sexta, involution of labial glands follows an autophagic pathway towards programmed cell death (PCD). We looked for evidence of both caspase dependent and independent pathways of PCD by assaying for caspases -1, -2, -3, and -6, proteasomal protease, and cathepsins B & L, using fluorogenic substrates and aldehyde and chloromethylketone inhibitors. The substrates FR-AMC and RR-AMC, preferentially degraded by cathepsins B and L, were the most rapidly degraded, increasing in rate as the gland involuted. Digestion of YVAD-AMC (preferential substrate for caspase-1) and DEVD-AMC (substrate for caspases-3 & -7) was barely detectable, less than 0.02% (on a per-unit-protein basis) of that seen in vertebrate embryos induced to undergo apoptosis. Cleavage of VDVAD-AFC (substrate for caspase -2) and VEID-AFC (substrate for caspase -6) was also assessed, but activity was negligible. Mitochondrial membrane permeabilization (MMP) and cytochrome c release were not detected. Exogenous caspase substrate, polyadenosyl ribose phosphorylase (PARP), is cleaved by labial gland extracts, but only at an acidic pH of 5.5-6.0, and into fragments different from those generated by caspases (confirmed by N-terminal sequencing). The cysteine protease inhibitor leupeptin inhibits PARP cleavage, but the caspase inhibitor DEVD-CHO does not. However, potential caspase-derived fragments of PARP are seen when cytochrome c and dATP are added to cytosolic extracts. Although apoptotic machinery is conserved and functional in this tissue, cell death occurs independently of caspases in metamorphosis. We also postulate that lysosomal proteases play the major proteolytic role similar to the caspase cascade seen in apoptosis. PMID:20405221

Facey, Caroline O B; Lockshin, Richard A

2010-06-01

87

Adaptive colouration in amphibians.  

PubMed

Amphibians, i.e. salamanders, frogs and caecilians show a wide range of bright colours in combination with contrasting patterns. There is variation among species, populations and also within species and populations. Furthermore, individuals often change colours during developmental stages or in response to environmental factors. This extraordinary variation means that there are excellent opportunities to test hypotheses of the adaptive significance of colours using amphibian species as models. We review the present view of functions of colouration in amphibians with the main focus on relatively unexplored topics. Variation in colouration has been found to play a role in thermoregulation, UV protection, predator avoidance and sexual signalling. However, many proposed cases of adaptive functions of colouration in amphibians remain virtually scientifically unexplored and surprisingly few genes influencing pigmentation or patterning have been detected. We would like to especially encourage more studies that take advantage of recent developments in measurement of visual properties of several possible signalling receivers (e.g. predators, competitors or mates). Future investigations on interactions between behaviour, ecology and vision have the potential to challenge our current view of the adaptive function of colouration in amphibians. PMID:23664831

Rudh, Andreas; Qvarnström, Anna

2013-01-01

88

Amphibian declines: an immunological perspective  

Microsoft Academic Search

Many, but not all, amphibian populations have been declining on all six continents on which they live. Although habitat destruction, direct application of toxicants, and introduction of predators\\/competitors are obvious causes of amphibian declines, many amphibians are dying of infectious diseases in relatively pristine habitats on several continents. In this paper, we review the patterns of these disease outbreaks and

Cynthia Carey; Nicholas Cohen; Louise Rollins-Smith

1999-01-01

89

Amphibian Embryology Tutorial  

NSDL National Science Digital Library

Amphibian Embryology Tutorial, originally created to supplement Jeff Hardin's Introduction to Animal Development course at the University of Wisconsin-Madison, is "part of an ongoing project designed to implement multimedia and computer-based learning materials in the university undergraduate classroom." The tutorial is organized by major stages of development: Oogenesis and fertilization, cleavage, gastrulation, and neurulation. The Web site also includes an explanation of why we use amphibians to study development. The tutorial presents detailed explanations of each developmental stage and makes generous use of diagrams, photographs, and movie clips. This Web site would be a terrific resource for students wishing to review amphibian embryology outside the classroom at their own pace.

90

DEVELOPMENTAL DIVERSITY OF AMPHIBIANS  

PubMed Central

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

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

2011-01-01

91

Amphibians of Olympic National Park  

USGS Publications Warehouse

Amphibians evolved from fishes about 360 million years ago and were the first vertebrates adapted to life on land. The word amphibian means "double life." It refers to the life history of many amphibians, which spend part of their life in water and part on land. There are three major groups of amphibians: salamanders, frogs, and toads, and caecilians. Salamanders, frogs, and toads can be found in Olympic National Park (ONP), but caecilians live only in tropical regions. Many amphibians are generalist predators, eating almost any prey they can fit into their mouths.

U.S. Geological Survey

2000-01-01

92

Rainforest: Reptiles and Amphibians  

ERIC Educational Resources Information Center

Rainforest reptiles and amphibians are a vibrantly colored, multimedia art experience. To complete the entire project one may need to dedicate many class periods to production, yet in each aspect of the project a new and important skill, concept, or element is being taught or reinforced. This project incorporates the study of warm and cool color…

Olson, Susanna

2006-01-01

93

Life-history evolution: at the origins of metamorphosis.  

PubMed

Metamorphosis is a widespread life history strategy of animals but apart from some model organisms it is poorly characterized. A recent study of moon jellies highlights the similarities and differences between the various types of metamorphosis and illuminates its molecular determinants. PMID:24556439

Holstein, Thomas W; Laudet, Vincent

2014-02-17

94

Interpreting in vivo Effects of Thyroid Synthesis Inhibitors through the Lens of in vitro and ex vivo Assays  

EPA Science Inventory

The US EPA has been charged to evaluate chemicals for their ability to disrupt endocrine pathways including estrogen, androgen, and thyroid hormone. Amphibian metamorphosis, which is regulated by thyroid hormone, is an ideal model system for investigating disruption of the thyroi...

95

Amphibian Disease Research at the University of Tennessee  

E-print Network

1 Amphibian Disease Research at the University of Tennessee Institute of Agriculture Matthew J. Gray Frog Virus 3 M. paratuberculosis Amphibian Disease Program Interactions of Cattle and Amphibians Goal: Justification: Food Safety Amphibian Conservation Amphibians may increase prevalence of foodborne

Gray, Matthew

96

Aquatic eutrophication promotes pathogenic infection in amphibians  

E-print Network

Aquatic eutrophication promotes pathogenic infection in amphibians Pieter T. J. Johnson* , Jonathan Ribeiroia ondatrae sequentially infects birds, snails, and amphibian larvae, frequently causing severe limb of snail hosts, and, ultimately, the intensity of infection in amphibians. Infection also negatively

Johnson, Pieter

97

Responses of Mammalian Insectivores, Amphibians, and Reptiles to Broad-Scale Manipulation of Coarse Woody Debris  

SciTech Connect

Sampled shrews at 9.3 ha plots from logs manually removed and control plots in loblolly pine forests of the Southeastern Coastal Plain. Capture rates of Cryptotis parva were lower at plots from which deadwood was removed whereas capture rates of Blarina cavolinensis and Sorex longirostris did not differ between control and removal plots. Cryptotis may have been most sensitive to removal plots due to low population density, hence poor ability to move into areas of low reproduction. (Second Abstract, p. 37)Presentation of evidence that juvenile amphibians including Ambystomatid salamanders may disperse hundreds of meter from their natal wetlands within the weeks to months following metamorphosis. Data indicates Ambystoma trigrinum metamorphs can take at least six months to disperse and en route use non-polar lipid reserves garnished as larvae. Report suggests a land management regime that allows for both juvenile amphibian dispersal and also the consumptive use of the surrounding landscape.

McCay, T.S.; Forschler, B.T.; Komoroski, M.J.; Ford, W.M.

2002-03-10

98

Amphibian development in microgravity  

NASA Technical Reports Server (NTRS)

The results of experiments performed by the U.S. Biosatellites 1 and 2 and the Gemini VIII and XII missions and by the Soviet Salyut and Soyuz missions on the effect of gravity on the development of prefertilized amphibian egg and, in particular, of the vestibular system of amphibian embryo are described. In these experiments, the condition of microgravity was reached only after the prefertilized eggs were in the early stages of first cell division or in the blastula stage. No significant changes were observed in the morphology of the embryos or in the vestibular system of embyos developed, respectively, for 2-5 days or 20 days under conditions of microgravity. Experiments planned for future spaceflights are discussed.

Souza, K. A.

1987-01-01

99

Amphibian Information Website  

NSDL National Science Digital Library

Dan Rasay of the Patuxent Wildlife Research Center (US Geological Survey), in collaboration with the National Park Service and the US Environmental Protection Agency, has developed a web-based searchable database system for amphibian related information. The site contains searchable bibliographic data, web links, and researchers' names. Projects can be located using a search based on genus or keywords. The creators of this new site are looking for feedback on its usefulness, particularly to the conservation community.

1997-01-01

100

Field Surveys of Amphibian Populations.  

ERIC Educational Resources Information Center

Describes a course on amphibian research for environmental science majors. Involves students in field studies and introduces them to investigative research. Evaluates the course. (Contains 19 references.) (YDS)

Brodman, Robert

2000-01-01

101

Amphibian metamorphosis as a model for studying the developmental actions of thyroid hormone  

Microsoft Academic Search

The thyroid hormones L-thyroxine and triiodo-L-thyronine have profound effects on postembryonic development of most vertebrates. Analysis of their action in mammals is vitiated by the exposure of the developing foetus to a number of maternal factors which do not allow one to specifically define the role of thyroid hormone (TH) or that of other hormones and factors that modulate its

Jamshed R Tata

1998-01-01

102

Chronic sublethal exposure to silver nanoparticles disrupts thyroid hormone signaling during Xenopus laevis metamorphosis.  

PubMed

Nanoparticles (NPs) are engineered in the nanoscale (<100nm) to have unique physico-chemical properties from their bulk counterparts. Nanosilver particles (AgNPs) are the most prevalent NPs in consumer products due to their strong antimicrobial action. While AgNP toxicity at high concentrations has been thoroughly investigated, the sublethal effects at or below regulatory guidelines are relatively unknown. Amphibian metamorphosis is mediated by thyroid hormone (TH), and initial studies with bullfrogs (Rana catesbeiana) indicate that low concentrations of AgNPs disrupt TH-dependent responses in premetamorphic tadpole tailfin tissue. The present study examined the effects of low, non-lethal, environmentally-relevant AgNP concentrations (0.018, 0.18 or 1.8?g/L Ag; ?10nm particle size) on naturally metamorphosing Xenopus laevis tadpoles in two-28 day chronic exposures beginning with either pre- or prometamorphic developmental stages. Asymmetric flow field flow fractionation with online inductively coupled plasma mass spectrometry and nanoparticle tracking analysis indicated a mixture of single AgNPs with homo-agglomerates in the exposure water with a significant portion (?30-40%) found as dissolved Ag. Tadpoles bioaccumulated AgNPs and displayed transient alterations in snout/vent and hindlimb length with AgNP exposure. Using MAGEX microarray and quantitative real time polymerase chain reaction transcript analyses, AgNP-induced disruption of five TH-responsive targets was observed. The increased mRNA abundance of two peroxidase genes by AgNP exposure suggests the presence of reactive oxygen species even at low, environmentally-relevant concentrations. Furthermore, differential responsiveness to AgNPs was observed at each developmental stage. Therefore, low concentrations of AgNPs had developmental stage-specific endocrine disrupting effects during TH-dependent metamorphosis. PMID:25531432

Carew, Amanda C; Hoque, M Ehsanul; Metcalfe, Chris D; Peyrot, Caroline; Wilkinson, Kevin J; Helbing, Caren C

2015-02-01

103

Conservation Biology of Caecilian Amphibians  

Microsoft Academic Search

Most of the available data on declining populations of amphibians pertain to frogs and, to a lesser extent, salamanders. In keeping with their generally less understood biology, the population trends and conservation status of caecilian amphibians (Gymnophiona) are also much less known. We reviewed reports of threats to and declines of populations of caecilians. Despite a lack of field-study details

DAVID J. GOWER; MARK WILKINSON

2005-01-01

104

Profound morphological and functional changes of rodent Purkinje cells between the first and the second postnatal weeks: a metamorphosis?  

PubMed Central

Between the first and the second postnatal week, the development of rodent Purkinje cells is characterized by several profound transitions. Purkinje cells acquire their typical dendritic “espalier” tree morphology and form distal spines. During the first postnatal week, they are multi-innervated by climbing fibers and numerous collateral branches sprout from their axons, whereas from the second postnatal week, the regression of climbing fiber multi-innervation begins, and Purkinje cells become innervated by parallel fibers and inhibitory molecular layer interneurons. Furthermore, their periods of developmental cell death and ability to regenerate their axon stop and their axons become myelinated. Thus a Purkinje cell during the first postnatal week looks and functions differently from a Purkinje cell during the second postnatal week. These fundamental changes occur in parallel with a peak of circulating thyroid hormone in the mouse. All these features suggest to some extent an interesting analogy with amphibian metamorphosis. PMID:22514522

Dusart, Isabelle; Flamant, Frederic

2012-01-01

105

Global Amphibian Declines:Global Amphibian Declines: What Have We Done?What Have We Done?  

E-print Network

1 Global Amphibian Declines:Global Amphibian Declines: What Have We Done?What Have We Done? Nikki amphibian populations · Amphibian biology - characteristics making them susceptible to declinesthem susceptible to declines · Direct anthropogenic (human caused) effects on amphibian declines · Indirect effects

Gray, Matthew

106

An examination of amphibian sensitivity to environmental contaminants: are amphibians poor  

E-print Network

LETTER An examination of amphibian sensitivity to environmental contaminants: are amphibians poor of worldwide amphibian declines. Amphibians earned their appellation, Ã?canaries in a coal mineÃ?, because, there has been no systematic evaluation of amphibian sensitivity to environmental challenges relative

Storfer, Andrew

107

What are amphibians and reptiles? Like birds and mammals, amphibians and  

E-print Network

What are amphibians and reptiles? Like birds and mammals, amphibians and reptiles are vertebrates, based on their surroundings. Amphibians Amphibians include frogs, toads, newts, and salamanders. Many amphibians have a complex life cycle that involves living both on land and in water. While most adult

New Hampshire, University of

108

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

SciTech Connect

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 126 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.

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

1999-11-01

109

Activation of sox3 gene by thyroid hormone in the developing adult intestinal stem cell during Xenopus metamorphosis.  

PubMed

The maturation of the intestine into the adult form involves the formation of adult stem cells in a thyroid hormone (T3)-dependent process in vertebrates. In mammals, this takes place during postembryonic development, a period around birth when the T3 level peaks. Due to the difficulty of manipulating late-stage, uterus-enclosed embryos, very little is known about the development of the adult intestinal stem cells. Interestingly, the remodeling of the intestine during the T3-dependent amphibian metamorphosis mimics the maturation of mammalian intestine. Our earlier microarray studies in Xenopus laevis revealed that the transcription factor SRY (sex-determining region Y)-box 3 (Sox3), well known for its involvement in neural development, was upregulated in the intestinal epithelium during metamorphosis. Here, we show that Sox3 is highly and specifically expressed in the developing adult intestinal progenitor/stem cells. We further show that its induction by T3 is independent of new protein synthesis, suggesting that Sox3 is directly activated by liganded T3 receptor. Thus, T3 activates Sox3 as one of the earliest changes in the epithelium, and Sox3 in turn may facilitate the dedifferentiation of the larval epithelial cells into adult stem cells. PMID:25211587

Sun, Guihong; Fu, Liezhen; Wen, Luan; Shi, Yun-Bo

2014-12-01

110

Appendix 56 Management of Montana's Amphibians  

E-print Network

Appendix 56 Management of Montana's Amphibians #12;Management of Montana's Amphibians: A Review. Management of Montana's amphibians: a review of factors that may present a risk to population viability...................................................................................................... 5 Table of Presence and Status Ranks for Amphibians on National Forests in Montana...... 6 Table

111

Exposure to coal combustion residues during metamorphosis elevates corticosterone content and adversely affects oral morphology, growth, and development in Rana sphenocephala  

SciTech Connect

Coal combustion residues (CCRs) are documented to negatively impact oral morphology, growth, and development in larval amphibians. It is currently unclear what physiological mechanisms may mediate these effects. Corticosterone, a glucocorticoid hormone, is a likely mediator because when administered exogenously it, like CCRs, also negatively influences oral morphology, growth, and development in larval amphibians. In an attempt to identify if corticosterone mediates these effects, we raised larval Southern Leopard Frogs, Rana sphenocephala, on either sand or CCR substrate and documented effects of sediment type on whole body corticosterone, oral morphology, and time to and mass at key metamorphic stages. Coal combustion residue treated tadpoles contained significantly more corticosterone than controls throughout metamorphosis. However, significantly more oral abnormalities occurred early in metamorphosis when differences in corticosterone levels between treatments were minimal. Overall, CCR-treated tadpoles took significantly more time to transition between key stages and gained less mass between stages than controls, but these differences between treatments decreased during later stages when corticosterone differences between treatments were greatest. Our results suggest endogenous increase in corticosterone content and its influence on oral morphology, growth and development is more complex than previously thought.

Peterson, J.D.; Peterson, V.A.; Mendonca, M.T. [Auburn University, Auburn, AL (USA). Dept. of Biological Science

2009-01-15

112

Batrachochytrium dendrobatidis prevalence and haplotypes in domestic and imported pet amphibians in Japan.  

PubMed

The international trade in amphibians is believed to have increased the spread of Batrachochytrium dendrobatidis (Bd), the fungal pathogen responsible for chytridiomycosis, which has caused a rapid decline in amphibian populations worldwide. We surveyed amphibians imported into Japan and those held in captivity for a long period or bred in Japan to clarify the Bd infection status. Samples were taken from 820 individuals of 109 amphibian species between 2008 and 2011 and were analyzed by a nested-PCR assay. Bd prevalence in imported amphibians was 10.3% (58/561), while it was 6.9% (18/259) in those in private collections and commercially bred amphibians in Japan. We identified the genotypes of this fungus using partial DNA sequences of the internal transcribed spacer (ITS) region. Sequencing of PCR products of all 76 Bd-positive samples revealed 11 haplotypes of the Bd ITS region. Haplotype A (DNA Data Bank of Japan accession number AB435211) was found in 90% (52/58) of imported amphibians. The results show that Bd is currently entering Japan via the international trade in exotic amphibians as pets, suggesting that the trade has indeed played a major role in the spread of Bd. PMID:24991744

Tamukai, Kenichi; Une, Yumi; Tominaga, Atsushi; Suzuki, Kazutaka; Goka, Koichi

2014-05-13

113

Chemosignals, hormones, and amphibian reproduction.  

PubMed

This article is part of a Special Issue "Chemosignals and Reproduction". Amphibians are often thought of as relatively simple animals especially when compared to mammals. Yet the chemosignaling systems used by amphibians are varied and complex. Amphibian chemosignals are particularly important in reproduction, in both aquatic and terrestrial environments. Chemosignaling is most evident in salamanders and newts, but increasing evidence indicates that chemical communication facilitates reproduction in frogs and toads as well. Reproductive hormones shape the production, dissemination, detection, and responsiveness to chemosignals. A large variety of chemosignals have been identified, ranging from simple, invariant chemosignals to complex, variable blends of chemosignals. Although some chemosignals elicit straightforward responses, others have relatively subtle effects. Review of amphibian chemosignaling reveals a number of issues to be resolved, including: 1) the significance of the complex, individually variable blends of courtship chemosignals found in some salamanders, 2) the behavioral and/or physiological functions of chemosignals found in anuran "breeding glands", 3) the ligands for amphibian V2Rs, especially V2Rs expressed in the main olfactory epithelium, and 4) the mechanism whereby transdermal delivery of chemosignals influences behavior. To date, only a handful of the more than 7000 species of amphibians has been examined. Further study of amphibians should provide additional insight to the role of chemosignals in reproduction. PMID:24945995

Woodley, Sarah

2014-06-16

114

Amphibian Declines and Sensitivity Analysis Biek et al. 2001 What is Missing In Amphibian Decline Research  

E-print Network

Amphibian Declines and Sensitivity Analysis Biek et al. 2001 1 What is Missing In Amphibian Decline;Amphibian Declines and Sensitivity Analysis Biek et al. 2001 2 value in the range the SD was calculated

Mills, L. Scott

115

Polarity of the Amphibian Egg  

NASA Technical Reports Server (NTRS)

Amphibian egg polarity and the mechanism which generates the polarity is addressed. Of particular concern is the question of whether the activation rotation which responds to gravity is a prerequisite for normal development.

Malacinski, G. M.

1983-01-01

116

Metapopulation Dynamics and Amphibian Conservation  

Microsoft Academic Search

In many respects, amphibian spatial dynamics resemble classical metapopulation models, in which subpopulations in breeding ponds blink in and out of existence and extinction and colonization rates are functions of pond spatial arrangement. This \\

David M. Marsh; Peter C. Trenham

2001-01-01

117

Climate warming mediates negative impacts of rapid pond drying for three amphibian species.  

PubMed

Anthropogenic climate change will present both opportunities and challenges for pool-breeding amphibians. Increased water temperature and accelerated drying may directly affect larval growth, development, and survival, yet the combined effects of these processes on larvae with future climate change remain poorly understood. Increased surface temperatures are projected to warm water and decrease water inputs, leading to earlier and faster wetland drying. So it is often assumed that larvae will experience negative synergistic impacts with combined warming and drying. However, an alternative hypothesis is that warming-induced increases in metabolic rate and aquatic resource availability might compensate for faster drying rates, generating antagonistic larval responses. We conducted a mesocosm experiment to test the individual and interactive effects of pool permanency (permanent vs. temporary) and water temperature (ambient vs. (+) -3 degrees C) on three anurans with fast-to-slow larval development rates (Great Basin spadefoot [Spea intermontana], Pacific chorus frog [Pseudacris regilla], and northern red-legged frog [Rana aurora]). We found that although tadpoles in warmed pools reached metamorphosis 15-17 days earlier, they did so with little cost (< 2 mm) to size, likely due to greater periphyton growth in warmed pools easing drying-induced resource competition. Warming and drying combined to act antagonistically on early growth (P = 0.06) and survival (P = 0.06), meaning the combined impact was less than the sum of the individual impacts. Warming and drying acted additively on time to and size at metamorphosis. These nonsynergistic impacts may result from cotolerance of larvae to warming and drying, as well as warming helping to offset negative impacts of drying. Our results indicate that combined pool warming and drying may not always be harmful for larval amphibians. However, they also demonstrate that antagonistic responses are difficult to predict, which poses a challenge to proactive conservation and management. Our study highlights the importance of considering the nature of multiple stressor interactions as amphibians are exposed to an increasing number of anthropogenic threats. PMID:24933805

O'Regan, Sacha M; Palen, Wendy J; Anderson, Sean C

2014-04-01

118

So You Think You Want a Pet Reptile or Amphibian?  

MedlinePLUS

... feeder rodents. How do feeder rodents, reptiles, and amphibians get Salmonella ? Feeder rodents, reptiles, and amphibians can ... infected with Salmonella from feeder rodents, reptiles, or amphibians? Because feeder rodents, reptiles, and amphibians can have ...

119

Why Does Amphibian Chytrid (Batrachochytrium dendrobatidis) Not Occur Everywhere? An Exploratory Study in Missouri Ponds  

PubMed Central

The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), is a globally emerging pathogen that has caused widespread amphibian population declines, extirpations, and extinctions. However, Bd does not occur in all apparently suitable amphibian populations, even within regions where it is widespread, and it is often unclear why Bd occurs in some habitats but not others. In this study, we rigorously surveyed the amphibian and invertebrate biodiversity of 29 ponds in Missouri, screened resident amphibian larvae (Rana (Lithobates) sp.) for Bd infection, and characterized the aquatic physiochemical environment of each pond (temperature pH, conductivity, nitrogen, phosphorus, and chlorophyll-a). Our goal was to generate hypotheses toward answering the question, “Why does Bd not occur in all apparently suitable habitats?” Bd occurred in assayed amphibians in 11 of the 29 ponds in our study area (38% of ponds). We found no significant relationship between any single biotic or abiotic variable and presence of Bd. However, multivariate analyses (nonmetric multidimensional scaling and permutational tests of dispersion) revealed that ponds in which Bd occurred were a restricted subset of all ponds in terms of amphibian community structure, macroinvertebrate community structure, and pond physiochemistry. In other words, Bd ponds from 6 different conservation areas were more similar to each other than would be expected based on chance. The results of a structural equation model suggest that patterns in the occurrence of Bd among ponds are primarily attributable to variation in macroinvertebrate community structure. When combined with recent results showing that Bd can infect invertebrates as well as amphibians, we suggest that additional research should focus on the role played by non-amphibian biota in determining the presence, prevalence, and pathogenicity of Bd in amphibian populations. PMID:24086681

Strauss, Alex; Smith, Kevin G.

2013-01-01

120

Inhibition of metamorphosis by RFamide neuropeptides in planula larvae of Hydractinia echinata  

Microsoft Academic Search

The primitive nervous system in planula larvae of Hydractinia echinata (Cnidaria) has sensory neurons containing LWamide or RFamide neuropeptides. LWamides have been shown to induce metamorphosis of planula larvae into adult polyps. We report here that RFamides act antagonistically to LWamides. RFamides inhibit metamorphosis when applied to planula larvae during metamorphosis induction by treatment with LWamides (or other inducing agents

Yuki Katsukura; Charles N. David; Cornelis J. P. Grimmelikhuijzen; Tsutomu Sugiyama

2003-01-01

121

Thyroid hormone-dependent metamorphosis in a direct developing frog.  

PubMed

The direct developing anuran, Eleutherodactylus coqui, lacks a tadpole, hatching as a tiny frog. We investigated the role of the metamorphic trigger, thyroid hormone (TH), in this unusual ontogeny. Expression patterns of the thyroid hormone receptors, TRalpha and TRbeta, were similar to those of indirect developers. TRbeta mRNA levels increased dramatically around the time of thyroid maturation, when remodeling events reminiscent of metamorphosis occur. Treatment with the goitrogen methimazole inhibited this remodeling, which was reinitiated on cotreatment with TH. Despite their radically altered ontogeny, direct developers still undergo a TH-dependent metamorphosis, which occurs before hatching. We propose a new model for the evolution of anuran direct development. PMID:10706622

Callery, E M; Elinson, R P

2000-03-14

122

This information sheet is for the care and use of amphibians. Potential Zoonotic Diseases for Amphibians  

E-print Network

This information sheet is for the care and use of amphibians. Potential Zoonotic Diseases for Amphibians The overall incidence of transmission of disease-producing agents from amphibians to humans is low. There are, however, a few agents that are found in amphibians and aquarium water that have the potential

Wood, Marcelo A.

123

Survey for the amphibian chytrid Batrachochytrium dendrobatidis in Hong Kong in native amphibians and in the international amphibian trade  

Microsoft Academic Search

Chytridiomycosis, caused by the pathogen Batrachochytrium dendrobatidis, is respon- sible for many amphibian declines and has been identified in wild amphibian populations on all con- tinents where they exist, except for Asia. In order to assess whether B. dendrobatidis is present on the native amphibians of Hong Kong, we sampled wild populations of Amolops hongkongensis, Paa exil- ispinosa, P. spinosa

Jodi J. L. Rowley; SKF Chan; WS Tang; R Speare; LF Skerratt; RA Alford; KS Cheung; CY Ho; R Campbell

2007-01-01

124

Vomeronasal System Chemosensory Systems in Amphibians  

E-print Network

Chemoreception FROGS SALAMANDERS CAECILIANS FUNCTION IN WATER AND AIR Taste Comparative Chemoreception in Secondarily Aquatic Amphibians FROGS SALAMANDERS CAECILIANS Evolution of the Chemical Senses in Secondarily Aquatic Amphibians PIPID FROGS SALAMANDRID NEWTS TYPHLONECTID CAECILIANS Conclusions In this chapter, we

Eisthen, Heather L.

125

Amphibians as Models for Studying Environmental Change  

Microsoft Academic Search

The use of amphibians as models in ecological research has a rich history. From an early foundation in studies of am- phibian natural history sprang generations of scientists who used amphibians as models to address fundamental ques- tions in population and community ecology. More recently, in the wake of an environment that human disturbances rapidly altered, ecologists have adopted amphibians

William A. Hopkins

126

Global amphibian declines: sorting the hypotheses  

Microsoft Academic Search

Reports of malformed amphibians and global amphibian declines have led to public concern, particularly because amphibians are thought to be indicator species of overall envi- ronmental health. The topic also draws scientific attention because there is no obvious, simple answer to the question of what is causing amphi- bian declines? Complex interactions of several anthropogenic factors are probably at work,

James P. Collins; Andrew Storfer

2003-01-01

127

Infectious disease and amphibian population declines  

Microsoft Academic Search

A series of recent papers have impli- cated pathogens and parasites in amphibian population declines. Here, we review evidence on the link between infectious disease and amphibian population declines. We conclude that available data provide the clearest link for the fungal disease amphibian chytridiomycosis, although other pathogens are also implicated. We suggest additional experimental and observa- tional data that need

Peter Daszak; Andrew A. Cunningham; Alex D. Hyatt

2003-01-01

128

BIOTIC FACTORS IN AMPHIBIAN POPULATION DECLINES  

EPA Science Inventory

Amphibians evolved in, and continue to exist in, habitats that are replete with many other organisms. Some of these organisms serve as prey for amphibians and others interact with amphibians as predators, competitors, pathogens, or symbionts. Still other organisms in their enviro...

129

Speciation, Species Boundaries and Phylogeography of Amphibians  

E-print Network

CHAPTER 4 Speciation, Species Boundaries and Phylogeography of Amphibians Miguel Vences and David B Speciation and their Application in A. Allozyme Threshold Values Amphibians B. Mitochondrial Threshold Values B. Characters Used to Define Amphibian C. Discordance among Datasets Species D. DNA Barcoding

Wake, David B.

130

The Reptiles and Amphibians Savannah River Plant  

E-print Network

SR0-NERP-2 The Reptiles and Amphibians of the Savannah River Plant by J. Whitfield Gib bons THE REPTILES AND AMPHIBIANS OF THE SAVANNAH RIVER PLANT by J. Whitfield Gibbons and Karen K. Patterson Savannah is to provide taxonomic, distributional, and ecological information on the reptiles and amphibians

Georgia, University of

131

Amphibian commerce and the threat of pathogen  

E-print Network

7/16/2011 1 Amphibian commerce and the threat of pathogen pollution Angela Picco, PhD United% for commercial purposes, mostly for pet trade (Smith et al., 2009) W.B. Karesh #12;7/16/2011 2 Amphibian trade · Pet trade · Food trade · Research, biomedical, education · Bait trade · 5 million live amphibians per

Gray, Matthew

132

Amphibians Used in Research and Teaching  

Microsoft Academic Search

Amphibians have long been utilized in scientific research and in education. Historically, investigators have accumu- lated a wealth of information on the natural history and biology of amphibians, and this body of information is con- tinually expanding as researchers describe new species and study the behaviors of these animals. Amphibians evolved as models for a variety of developmental and physiological

Dorcas P. O'Rourke

2007-01-01

133

Elemental concentration in mealworm beetle (Tenebrio molitor L.) during metamorphosis.  

PubMed

Mealworm beetles have been used in numerous experiments as bioindicators. The aim of our experiment was to study the elemental composition in three larvae, pupae and first and second generation adult stages during their life cycle. We selected 180 larvae from a genetically similar population and put them in three groups, in two boxes (60 larvae in each box). Larvae were fed with mashed potato made of the same quality and quantity of potato powder. Then, we selected 10 individuals from each stage to the elemental analysis, using the ICP-OES method. The following elements were analysed in the studied stages: Ca, Cu, Fe, K, Mg, Mn, Na, P, S, Sr and Zn. The results of principal component analysis demonstrated that based on elemental composition, different stages were separated with each other, but in the cases of the three larvae stages, high overlap was found. The results of the GLM ANOVA showed significant differences between the different stages of metamorphosis-based elemental composition. Our results show that the calcium and magnesium were found in a relatively high concentration, while the iron and zinc may be essential elements during the metamorphosis. Our results also show that in insect, the concentration of sodium was higher than in the pupa which may cause by hemolymph. We also demonstrated that the metamorphosis has an effect on the concentration of elements. Our study shows that in the different stages of insects, there are significant changes in the elemental composition of different stages of insects during their metamorphosis. PMID:23695727

Simon, Edina; Baranyai, Edina; Braun, Mihály; Fábián, István; Tóthmérész, Béla

2013-07-01

134

Agricultural ponds support amphibian populations  

USGS Publications Warehouse

In some agricultural regions, natural wetlands are scarce, and constructed agricultural ponds may represent important alternative breeding habitats for amphibians. Properly managed, these agricultural ponds may effectively increase the total amount of breeding habitat and help to sustain populations. We studied small, constructed agricultural ponds in southeastern Minnesota to assess their value as amphibian breeding sites. Our study examined habitat factors associated with amphibian reproduction at two spatial scales: the pond and the landscape surrounding the pond. We found that small agricultural ponds in southeastern Minnesota provided breeding habitat for at least 10 species of amphibians. Species richness and multispecies reproductive success were more closely associated with characteristics of the pond (water quality, vegetation, and predators) compared with characteristics of the surrounding landscape, but individual species were associated with both pond and landscape variables. Ponds surrounded by row crops had similar species richness and reproductive success compared with natural wetlands and ponds surrounded by nongrazed pasture. Ponds used for watering livestock had elevated concentrations of phosphorus, higher turbidity, and a trend toward reduced amphibian reproductive success. Species richness was highest in small ponds, ponds with lower total nitrogen concentrations, tiger salamanders (Ambystoma tigrinum) present, and lacking fish. Multispecies reproductive success was best in ponds with lower total nitrogen concentrations, less emergent vegetation, and lacking fish. Habitat factors associated with higher reproductive success varied among individual species. We conclude that small, constructed farm ponds, properly managed, may help sustain amphibian populations in landscapes where natural wetland habitat is rare. We recommend management actions such as limiting livestock access to the pond to improve water quality, reducing nitrogen input, and avoiding the introduction of fish.

Knutson, M.G.; Richardson, W.B.; Reineke, D.M.; Gray, B.R.; Parmelee, J.R.; Weick, S.E.

2004-01-01

135

Tennessee Amphibian Monitoring Program (TAMP)  

NSDL National Science Digital Library

The Tennessee Wildlife Resources Agency (TWRA) and the Tennessee Department of Environment and Conservation co-sponsor the Tennessee Amphibian Monitoring Program (TAMP). A volunteer-based, multi-agency effort "to assess the current status of amphibians (frogs, toads, and salamanders)" across the state, TAMP is open to all interested participants. The homepage introduces and describes the need for TAMP, and provides a brief list of related sites. Also at the TAMP site are detailed survey protocols (with accompanying color photographs of frogs and toads) and a list of selected references.

136

Plasticity of lung development in the amphibian, Xenopus laevis  

PubMed Central

Summary Contrary to previous studies, we found that Xenopus laevis tadpoles raised in normoxic water without access to air can routinely complete metamorphosis with lungs that are either severely stunted and uninflated or absent altogether. This is the first demonstration that lung development in a tetrapod can be inhibited by environmental factors and that a tetrapod that relies significantly on lung respiration under unstressed conditions can be raised to forego this function without adverse effects. This study compared lung development in untreated, air-deprived (AD) and air-restored (AR) tadpoles and frogs using whole mounts, histology, BrdU labeling of cell division and antibody staining of smooth muscle actin. We also examined the relationship of swimming and breathing behaviors to lung recovery in AR animals. Inhibition and recovery of lung development occurred at the stage of lung inflation. Lung recovery in AR tadpoles occurred at a predictable and rapid rate and correlated with changes in swimming and breathing behavior. It thus presents a new experimental model for investigating the role of mechanical forces in lung development. Lung recovery in AR frogs was unpredictable and did not correlate with behavioral changes. Its low frequency of occurrence could be attributed to developmental, physical and behavioral changes, the effects of which increase with size and age. Plasticity of lung inflation at tadpole stages and loss of plasticity at postmetamorphic stages offer new insights into the role of developmental plasticity in amphibian lung loss and life history evolution. PMID:24337117

Rose, Christopher S.; James, Brandon

2013-01-01

137

North American Endangered Amphibians Card Game  

NSDL National Science Digital Library

In this activity, learners can play two card games related to endangered species, specifically North American amphibians. In version one, "Guess My Amphibian," a learner secretly selects a card and players take turns asking yes-or-no questions to identify the mystery amphibian. In version two, "Guess My Rule," a learner selects a secret rule about amphibians and players try to identify the rule. For an extra challenge, use string circles to form a Venn Diagram that players can use to sort the amphibians and play a more challenging version of "Guess My Rule."

Terc; Zoo, Omaha'S H.; Services, Institute O.

2012-12-20

138

Pesticide Mixtures, Endocrine Disruption, and Amphibian Declines: Are We Underestimating the Impact?  

PubMed Central

Amphibian populations are declining globally at an alarming rate. Pesticides are among a number of proposed causes for these declines. Although a sizable database examining effects of pesticides on amphibians exists, the vast majority of these studies focus on toxicological effects (lethality, external malformations, etc.) at relatively high doses (parts per million). Very few studies focus on effects such as endocrine disruption at low concentrations. Further, most studies examine exposures to single chemicals only. The present study examined nine pesticides (four herbicides, two fungicides, and three insecticides) used on cornfields in the midwestern United States. Effects of each pesticide alone (0.1 ppb) or in combination were examined. In addition, we also examined atrazine and S-metolachlor combined (0.1 or 10 ppb each) and the commercial formulation Bicep II Magnum, which contains both of these herbicides. These two pesticides were examined in combination because they are persistent throughout the year in the wild. We examined larval growth and development, sex differentiation, and immune function in leopard frogs (Rana pipiens). In a follow-up study, we also examined the effects of the nine-compound mixture on plasma corticosterone levels in male African clawed frogs (Xenopus laevis). Although some of the pesticides individually inhibited larval growth and development, the pesticide mixtures had much greater effects. Larval growth and development were retarded, but most significantly, pesticide mixtures negated or reversed the typically positive correlation between time to metamorphosis and size at metamorphosis observed in controls: exposed larvae that took longer to metamorphose were smaller than their counterparts that metamorphosed earlier. The nine-pesticide mixture also induced damage to the thymus, resulting in immunosuppression and contraction of flavobacterial meningitis. The study in X. laevis revealed that these adverse effects may be due to an increase in plasma levels of the stress hormone corticosterone. Although it cannot be determined whether all the pesticides in the mixture contribute to these adverse effects or whether some pesticides are effectors, some are enhancers, and some are neutral, the present study revealed that estimating ecological risk and the impact of pesticides on amphibians using studies that examine only single pesticides at high concentrations may lead to gross underestimations of the role of pesticides in amphibian declines. PMID:16818245

Hayes, Tyrone B.; Case, Paola; Chui, Sarah; Chung, Duc; Haeffele, Cathryn; Haston, Kelly; Lee, Melissa; Mai, Vien Phoung; Marjuoa, Youssra; Parker, John; Tsui, Mable

2006-01-01

139

METAPOPULATION DYNAMICS AND AMPHIBIAN CONSERVATION  

EPA Science Inventory

In many respects, amphibian spatial dynamics resemble classical metapopulation models, where subpopulations in breeding ponds blink in and out of existance and where extinction and colonization rates are functions of pond spatial arrangement. This "ponds-as-patches" view of amphi...

140

Multiple overseas dispersal in amphibians.  

PubMed Central

Amphibians are thought to be unable to disperse over ocean barriers because they do not tolerate the osmotic stress of salt water. Their distribution patterns have therefore generally been explained by vicariance biogeography. Here, we present compelling evidence for overseas dispersal of frogs in the Indian Ocean region based on the discovery of two endemic species on Mayotte. This island belongs to the Comoro archipelago, which is entirely volcanic and surrounded by sea depths of more than 3500 m. This constitutes the first observation of endemic amphibians on oceanic islands that did not have any past physical contact to other land masses. The two species of frogs had previously been thought to be nonendemic and introduced from Madagascar, but clearly represent new species based on their morphological and genetic differentiation. They belong to the genera Mantidactylus and Boophis in the family Mantellidae that is otherwise restricted to Madagascar, and are distinguished by morphology and mitochondrial and nuclear DNA sequences from mantellid species occurring in Madagascar. This discovery permits us to update and test molecular clocks for frogs distributed in this region. The new calibrations are in agreement with previous rate estimates and indicate two further Cenozoic transmarine dispersal events that had previously been interpreted as vicariance: hyperoliid frogs from Africa to Madagascar (Heterixalus) and from Madagascar to the Seychelles islands (Tachycnemis). Our results provide the strongest evidence so far that overseas dispersal of amphibians exists and is no rare exception, although vicariance certainly retains much of its importance in explaining amphibian biogeography. PMID:14667332

Vences, Miguel; Vieites, David R; Glaw, Frank; Brinkmann, Henner; Kosuch, Joachim; Veith, Michael; Meyer, Axel

2003-01-01

141

Ecopathology of Ranaviruses Infecting Amphibians  

PubMed Central

Ranaviruses are capable of infecting amphibians from at least 14 families and over 70 individual species. Ranaviruses infect multiple cell types, often culminating in organ necrosis and massive hemorrhaging. Subclinical infections have been documented, although their role in ranavirus persistence and emergence remains unclear. Water is an effective transmission medium for ranaviruses, and survival outside the host may be for significant duration. In aquatic communities, amphibians, reptiles and fish may serve as reservoirs. Controlled studies have shown that susceptibility to ranavirus infection and disease varies among amphibian species and developmental stages, and likely is impacted by host-pathogen coevolution, as well as, exogenous environmental factors. Field studies have demonstrated that the likelihood of epizootics is increased in areas of cattle grazing, where aquatic vegetation is sparse and water quality is poor. Translocation of infected amphibians through commercial trade (e.g., food, fish bait, pet industry) contributes to the spread of ranaviruses. Such introductions may be of particular concern, as several studies report that ranaviruses isolated from ranaculture, aquaculture, and bait facilities have greater virulence (i.e., ability to cause disease) than wild-type isolates. Future investigations should focus on the genetic basis for pathogen virulence and host susceptibility, ecological and anthropogenic mechanisms contributing to emergence, and vaccine development for use in captive populations and species reintroduction programs. PMID:22163349

Miller, Debra; Gray, Matthew; Storfer, Andrew

2011-01-01

142

Forecasting changes in amphibian biodiversity: aiming at a moving target  

E-print Network

Forecasting changes in amphibian biodiversity: aiming at a moving target James P. Collins1 Amphibian Populations Task Force (DAPTF), UK Amphibian population declines and sudden species' extinctions by our poor knowledge of the amphibian fauna in many parts of the world. Amphibian taxa are still being

143

Interactions of an insecticide with competition and pond drying in amphibian communities  

USGS Publications Warehouse

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.

Boone, M.D.; Semlitsch, R.D.

2002-01-01

144

Interactions of an insecticide, herbicide, and natural stressors in amphibian community mesocosms  

USGS Publications Warehouse

Amphibians developing in wetlands embedded within or near agricultural lands may frequently encounter chemical mixtures. The objectives of our study were to determine the effects that post-application concentrations of an insecticide (carbaryl) and an herbicide (atrazine) have on body mass, development, and survival of two anuran species (southern leopard frog, Rana sphenocephala; American toad, Bufo americanus) and two caudate species (spotted salamander, Ambystoma maculatum; small-mouthed salamander, A. texanum) reared in outdoor cattle tank mesocosms. In one experiment, we manipulated tadpole density (low or high), carbaryl exposure (0, 3.5, 7.0 mg/L), and atrazine exposure (0 or 200 ??g/L) to test for effects on development, mass, and survival of larvae. In a second experiment, we manipulated pond hydroperiod (constant or drying), carbaryl exposure (0 or 5 mg/L), and atrazine exposure (0 or 200 ??g/L) to test for effects on mass, time, and survival to metamorphosis. Salamanders were virtually eliminated in carbaryl treatments, indicating that at realistic levels, this insecticide could cause population declines for salamanders in contaminated habitats. Carbaryl also had negative effects on toad survival. Exposure to atrazine had negative effects on body size, development, and time to metamorphosis in anuran species, which were associated with reduced chlorophyll levels. Both chemicals interacted significantly with density or hydroperiod, indicating that the environmental conditions could influence the impact of a contaminant. A significant atrazine-by-carbaryl interaction resulted in smaller and less developed spotted salamander larvae than in control ponds. Atrazine exposure, however, appeared to moderate negative effects of carbaryl for spotted salamanders. Our research suggests that important changes in the community's food web result from chemical exposure, which influence the susceptibility of amphibian species to contaminants.

Boone, M.D.; James, S.M.

2003-01-01

145

Effects of acute and chronic acidification on three larval amphibians that breed in temporary ponds  

SciTech Connect

This study explored the effects of acute (7 days) and chronic (4 months) exposure to pH 4.2 on three species of larval amphibians, Ambystoma jeffersonianum, Ambystoma maculatum, and Rana sylvatica. Acute tests were conducted in 24 impermeable enclosures in three temporary ponds. Total dissolved aluminum was higher in acidified enclosures in comparison with controls (pH 4.2, [Al] approximately 10-30 microM and pH greater than 4.7, [Al] approximately 5-15 microM, respectively). Greater mortality of A. jeffersonianum occurred at pH 4.2 than at pH greater than 4.7, whereas survival of A. maculatum and R. sylvatica were unaffected by pH. Mean wet masses of R. sylvatica were significantly lower at pH 4.2 than at pH greater than 4.7, but mean wet masses of surviving A. jeffersonianum and A. maculatum were not influenced by pH. There were no pH-related differences in body sodium concentration in larval R. sylvatica. Chronic acidification of mesocosms to pH 4.2 ([Al] approximately 16 microM) (controls = pH greater than 6, [Al] approximately 0.1 microM) resulted in total mortality of A. jeffersonianum. Survival of A. maculatum and R. sylvatica were not associated with pH, but survival of A. maculatum was low at both pH levels. Time to metamorphosis was longer for R. sylvatica maintained at pH 4.2, but not for A. maculatum. No differences in wet masses at metamorphosis were observed for R. sylvatica or A. maculatum. These results indicate that short and long term acidification of temporary wetlands could dramatically affect amphibians which rely upon them as breeding sites, either by causing mortality or by decreasing growth rates.

Rowe, C.L.; Sadinski, W.J.; Dunson, W.A. (Pennsylvania State Univ., University Park (United States))

1992-10-01

146

Effects of Pond Salinization on Survival Rate of Amphibian Hosts Infected with the Chytrid Fungus.  

PubMed

The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of amphibian populations worldwide, but management options are limited. Recent studies show that sodium chloride (NaCl) has fungicidal properties that reduce the mortality rates of infected hosts in captivity. We investigated whether similar results can be obtained by adding salt to water bodies in the field. We increased the salinity of 8 water bodies to 2 or 4 ppt and left an additional 4 water bodies with close to 0 ppt and monitored salinity for 18 months. Captively bred tadpoles of green and golden bell frog (Litoria aurea) were released into each water body and their development, levels of B. dendrobatidis infection, and survival were monitored at 1, 4, and 12 months. The effect of salt on the abundance of nontarget organisms was also investigated in before and after style analyses. Salinities remained constant over time with little intervention. Hosts in water bodies with 4 ppt salt had a significantly lower prevalence of chytrid infection and higher survival, following metamorphosis, than hosts in 0 ppt salt. Tadpoles in the 4 ppt group were smaller in length after 1 month in the release site than those in the 0 and 2 ppt groups, but after metamorphosis body size in all water bodies was similar . In water bodies with 4 ppt salt, the abundance of dwarf tree frogs (Litoria fallax), dragonfly larvae, and damselfly larvae was lower than in water bodies with 0 and 2 ppt salt, which could have knock-on effects for community structure. Based on our results, salt may be an effective field-based B. dendrobatidis mitigation tool for lentic amphibians that could contribute to the conservation of numerous susceptible species. However, as in all conservation efforts, these benefits need to be weighed against negative effects on both target and nontarget organisms. PMID:25354647

Stockwell, Michelle Pirrie; Storrie, Lachlan James; Pollard, Carla Jean; Clulow, John; Mahony, Michael Joseph

2014-10-29

147

Effects of amphibian chytrid fungus exposure on American toads in the presence of an insecticide.  

PubMed

Abiotic factors such as pesticides may alter the impact of a pathogen on hosts, which could have implications for host-pathogen interactions and may explain variation in disease outbreaks in nature. In the present laboratory experiment, American toad (Anaxyrus americanus) metamorphs were exposed to the amphibian chytrid fungal pathogen Batrachochytrium dendrobatidis (Bd) and environmentally relevant concentrations of the insecticide malathion to determine whether malathion altered the effects of Bd exposure on growth and survival of toad metamorphs. Exposure to Bd significantly decreased survival over the 51 d of the experiment, suggesting that Bd could reduce recruitment into the terrestrial life stage when exposure occurs at metamorphosis. Malathion did not impact survival, but a 12-h exposure at metamorphosis significantly reduced terrestrial growth. Toads that were exposed to both Bd and malathion showed a nonsignificant trend toward the smallest growth compared with other treatments. The present study suggests that Bd may pose a threat to American toads even though population declines have not been observed for this species; in addition, the presence of both the insecticide malathion and Bd could reduce terrestrial growth, which could have implications for lifetime fitness and suggests that environmental factors could play a role in pathogen impacts in nature. PMID:25099070

Wise, Rayona S; Rumschlag, Samantha L; Boone, Michelle D

2014-11-01

148

On natural metamorphosis inducers of the cnidarians Hydractinia echinata (Hydrozoa) and Aurelia aurita (Scyphozoa)  

NASA Astrophysics Data System (ADS)

Hydractinia echinata and Aurelia aurita produce motile larvae which undergo metamorphosis to sessile polyps when induced by external cues. The polyps are found at restricted sites, A. aurita predominantly on rocks close to the shore, H. echinata on shells inhabited by hermit crabs. It has been argued that the differential distribution of the polyps in their natural environment largely reflects the distribution of the natural metamorphosis-inducing cues. In the case of H. echinata, bacteria of the genus Alteromonas were argued to meet these conditions. We found that almost all substrates collected in the littoral to induce metamorphosis in H. echinata, and several bacterial strains isolated from the sea, including the common E. coli, induce metamorphosis efficiently. In A. aurita metamorphosis may be induced by the water-air interface, whereby metamorphosis precedes (final) settlement.

Kroiher, M.; Berking, S.

149

Do hormone-modulating chemicals impact on reproduction and development of wild amphibians?  

PubMed

Globally, amphibians are undergoing a precipitous decline. At the last estimate in 2004, 32% of the approximately 6000 species were threatened with extinction and 43% were experiencing significant declines. These declines have been linked with a wide range of environmental pressures from habitat loss to climate change, disease and pollution. This review evaluates the evidence that endocrine-disrupting contaminants (EDCs) - pollutants that affect hormone systems - are impacting on wild amphibians and contributing to population declines. The review is limited to anurans (frogs and toads) as data for effects of EDCs on wild urodeles (salamanders, newts) or caecilians (limbless amphibians) are extremely limited. Evidence from laboratory studies has shown that a wide range of chemicals have the ability to alter hormone systems and affect reproductive development and function in anurans, but for the most part only at concentrations exceeding those normally found in natural environments. Exceptions can be found for exposures to the herbicide atrazine and polychlorinated biphenyls in leopard frogs (Rana pipiens) and perchlorate in African clawed frogs (Xenopus laevis). These contaminants induce feminising effects on the male gonads (including 'intersex' - oocytes within testes) at concentrations measured in some aquatic environments. The most extensive data for effects of an EDC in wild amphibian populations are for feminising effects of atrazine on male gonad development in regions across the USA. Even where strong evidence has been provided for feminising effects of EDCs, however, the possible impact of these effects on fertility and breeding outcome has not been established, making inference for effects on populations difficult. Laboratory studies have shown that various chemicals, including perchlorate, polychlorinated biphenyls and bromodiphenylethers, also act as endocrine disrupters through interfering with thyroid-dependent processes that are fundamental for amphibian metamorphosis. Perchlorate has also been shown to induce these effects in wild anuran populations from perchlorate-contaminated environments. Overall, the published data available suggest that some health effects observed in wild anuran populations, most notably intersex, likely have a chemical aetiology; however they derive only from very few anuran species and for a few pesticides at field sites in the USA. To understand better the impacts of EDCs on wild anuran populations, as well as other amphibian groups, assessment of fertility in exposed animals are required. Development of non-destructive biomarkers that are indicative of specific EDC-effect mechanisms are also needed to allow the study of vulnerable populations. This will help to distinguish the effects of EDCs from other environmental and/or genetic influences on development and reproduction. PMID:25335651

Orton, Frances; Tyler, Charles R

2014-10-22

150

Mesoderm Induction in Amphibians: The Role of TGF-beta 2Like Factors  

Microsoft Academic Search

Mesoderm induction in the amphibian embryo can be studied by exposing animal region explants (destined to become ectoderm) to appropriate stimuli and assaying the appearance of mesodermal products like alpha -actin messenger RNA. Transforming growth factor beta 2 (TGF-beta 2), but not TGF-beta 1, was active in alpha -actin induction, while addition of fibroblast growth factor had a small synergistic

Frederic Rosa; Anita B. Roberts; David Danielpour; Linda L. Dart; Michael B. Sporn; Igor B. Dawid

1988-01-01

151

DEVELOPMENT OF AMPHIBIAN-BASED MODELS OF THYROID-AXIS DISRUPTION  

EPA Science Inventory

The research presented here describes the development of in vivo and in vitro assay systems to test chemicals for their ability to alter the HPT-axis. This data derived from this research will be used to support development of diagnostic indicators for use with amphibian whole o...

152

Spiny lobster development: mechanisms inducing metamorphosis to the puerulus: a review  

Microsoft Academic Search

This review outlines current knowledge of mechanisms effecting metamorphosis in decapod crustaceans and insects. The comparative\\u000a approach demonstrates some of the complexities that need resolving to find an answer to the question raised frequently by\\u000a ecologists: “What triggers metamorphosis in spiny lobsters?” It is evident that crustacean moulting and metamorphosis are\\u000a genetically controlled through endocrine systems that mediate gene expression.

Paulette S. McWilliam; Bruce F. Phillips

2007-01-01

153

Metamorphosis of Hydractinia echinata —natural versus artificial induction and developmental plasticity  

Microsoft Academic Search

Many marine invertebrates reproduce through a larval stage. The settlement and metamorphosis of most of the species are synchronised\\u000a and induced by environmental organisms, mainly bacteria. The hydrozoan Hydractinia echinata has become a model organism for metamorphosis of marine invertebrates. In this species, bacteria, e.g. Pseudoalteromonas espejiana, are the natural inducers of metamorphosis. Like in other species of marine invertebrates,

Stefanie Seipp; Jürgen Schmich; Tina Kehrwald; Thomas Leitz

2007-01-01

154

INVASIVE PLANTS AND NATIVE AMPHIBIANS: THE IMPLICATIONS FOR AMPHIBIAN CONSERVATION IN EASTERN NORTH AMERICA.  

E-print Network

??Regula Meyer, Lisa K., Ph.D., December 2013BIOLOGYINVASIVE PLANTS AND NATIVE AMPHIBIANS: THE IMPLICATIONS FOR AMPHIBIAN CONSERVATION IN EASTERN NORTH AMERICA (247 PP.)Adviser of Dissertation: Oscar… (more)

Regula Meyer, Lisa K.

2013-01-01

155

Amphibian Pathogen Batrachochytrium dendrobatidis Is Inhibited by the Cutaneous Bacteria of Amphibian Species  

E-print Network

Amphibian Pathogen Batrachochytrium dendrobatidis Is Inhibited by the Cutaneous Bacteria parts of the world are associated with a lethal fungal pathogen, Batrachochytrium dendrobatidis. Using The fungal pathogen Batrachochytrium dendrobatidis causes amphibian mortality and is associated

James, Timothy

156

Subtype-specific neuronal remodeling during Drosophila metamorphosis.  

PubMed

During metamorphosis in holometabolous insects, the nervous system undergoes dramatic remodeling as it transitions from its larval to its adult form. Many neurons are generated through post-embryonic neurogenesis to have adult-specific roles, but perhaps more striking is the dramatic remodeling that occurs to transition neurons from functioning in the larval to the adult nervous system. These neurons exhibit a remarkable degree of plasticity during this transition; many subsets undergo programmed cell death, others remodel their axonal and dendritic arbors extensively, whereas others undergo trans-differentiation to alter their terminal differentiation gene expression profiles. Yet other neurons appear to be developmentally frozen in an immature state throughout larval life, to be awakened at metamorphosis by a process we term temporally-tuned differentiation. These multiple forms of remodeling arise from subtype-specific responses to a single metamorphic trigger, ecdysone. Here, we discuss recent progress in Drosophila melanogaster that is shedding light on how subtype-specific programs of neuronal remodeling are generated during metamorphosis. PMID:23579264

Veverytsa, Lyubov; Allan, Douglas W

2013-01-01

157

Tropical amphibian populations experience higher disease risk in natural habitats  

E-print Network

Tropical amphibian populations experience higher disease risk in natural habitats C. Guilherme drivers of global amphibian declines, yet the interaction between them remains largely un- explored. Here, and infection intensity of the chytrid fungus Batrachochytrium dendrobatidis (Bd) in amphibian populations

Zamudio, Kelly R.

158

Management and Conservation Article Differential Responses of Postmetamorphic Amphibians to  

E-print Network

Management and Conservation Article Differential Responses of Postmetamorphic Amphibians to Cattle amphibian declines have been linked to various anthropogenic land uses. Recent studies have documented negative impacts of cropland agriculture and deforestation on amphibians; however, few have examined

Gray, Matthew

159

Bioaccumulation of trace elements in omnivorous amphibian larvae: Implications for amphibian health and contaminant transport  

Microsoft Academic Search

Despite the influence that amphibians have on the flow of energy and nutrients in ecological systems, the role that amphibians play in transporting contaminants through food webs has received very little attention. This study was undertaken to investigate bioaccumulation of trace elements in amphibians relative to other small aquatic organisms in a contaminated wetland. We collected bullfrog larvae (Rana catesbeiana)

Jason M. Unrine; William A. Hopkins; Christopher S. Romanek; Brian P. Jackson

2007-01-01

160

Global diversity of amphibians (Amphibia) in freshwater  

Microsoft Academic Search

This article present a review of species numbers, biogeographic patterns and evolutionary trends of amphibians in freshwater.\\u000a Although most amphibians live in freshwater in at least their larval phase, many species have evolved different degrees of\\u000a independence from water including direct terrestrial development and viviparity. Of a total of 5,828 amphibian species considered\\u000a here, 4,117 are aquatic in that they

Miguel Vences; Jörn Köhler

2008-01-01

161

Global diversity of amphibians (Amphibia) in freshwater  

Microsoft Academic Search

This article present a review of species numbers, biogeographic patterns and evolutionary trends of amphibians in freshwater.\\u000a Although most amphibians live in freshwater in at least their larval phase, many species have evolved different degrees of\\u000a independence from water including direct terrestrial development and viviparity. Of a total of 5,828 amphibian species considered\\u000a here, 4,117 are aquatic in that they

Miguel Vences; Jörn Köhler

162

Ecology. Global amphibian population declines.  

PubMed

The decline and disappearance of relatively undisturbed populations of amphibians in several high-altitude regions since the 1970s suggests that they may have suffered a global decline, perhaps with a common cause or causes. Houlahan et al. examined means of trends for 936 amphibian populations and concluded that global declines began in the late 1950s, peaked in the 1960s, and have continued at a reduced rate since. Here we re-analyse their data using a method that accounts for the sampling of different populations over different time periods, and find evidence of a mean global decline in monitored populations only in the 1990s. However it is calculated, the global mean not only masks substantial spatial and temporal variation in population trends and sampling effort, but also fails to distinguish between a global decline with global causes and the cumulative effects of local declines with local causes. PMID:11484041

Alford, R A; Dixon, P M; Pechmann, J H

2001-08-01

163

Female Sexual Arousal in Amphibians  

PubMed Central

Rather than being a static, species specific trait, reproductive behavior in female amphibians is variable within an individual during the breeding season when females are capable of reproductive activity. Changes in receptivity coincide with changes in circulating estrogen. Estrogen is highest at the point when females are ready to choose a male and lay eggs. At this time female receptivity (her probability of responding to a male vocal signal) is highest and her selectivity among conspecific calls (measured by her probability of responding to a degraded or otherwise usually unattractive male signal) is lowest. These changes occur even though females retain the ability to discriminate different acoustic characteristics of various conspecific calls. After releasing her eggs, female amphibians quickly become less receptive and more choosy in terms of their responses to male sexual advertisement signals. Male vocal signals stimulate both behavior and estrogen changes in amphibian females making mating more probable. The changes in female reproductive behavior are the same as those generally accepted as indicative of a change in female sexual arousal leading to copulation. They are situationally triggered, gated by interactions with males, and decline with the consummation of sexual reproduction with a chosen male. The changes can be triggered by either internal physiological state or by the presence of stimuli presented by males, and the same stimuli change both behavior and physiological (endocrine) state in such a way as to make acceptance of a male more likely. Thus amphibian females demonstrate many of the same general characteristics of changing female sexual state that in mammals indicate sexual arousal. PMID:20816968

Wilczynski, Walter; Lynch, Kathleen S.

2010-01-01

164

Bacterial and parasitic diseases of amphibians.  

PubMed

Whether in private practice or in a zoologic setting, veterinarians of the exotic animal persuasion are asked to work on amphibians. Veterinarians are able to evaluate amphibians thoroughly for medical issues, with infectious diseases at the forefront. Until quite recently, many infectious diseases were unknown or even misdiagnosed as being caused by opportunistic secondary organisms. Although Batrachochytrium dendrobates and viral diseases are in the forefront of research for amphibians, parasitic and bacterial diseases often present secondarily and, occasionally, even as the primary cause. Full diagnostic workups, when possible, can be critical in determining all the factors involved in morbidity and mortality issues in amphibians. PMID:19732711

Klaphake, Eric

2009-09-01

165

In situ effects of pesticides on amphibians in the Sierra Nevada.  

PubMed

For more than 20 years, conservationists have agreed that amphibian populations around the world are declining. Results obtained through laboratory or mesocosm studies and measurement of contaminant concentrations in areas experiencing declines have supported a role of contaminants in these declines. The current study examines the effects of contaminant exposure to amphibians in situ in areas actually experiencing declines. Early larval Pseudacris regilla were translocated among Lassen Volcanic, Yosemite and Sequoia National Parks, California, USA and caged in wetlands in 2001 and 2002 until metamorphosis. Twenty contaminants were identified in tadpoles with an average of 1.3-5.9 (maximum = 10) contaminants per animal. Sequoia National Park, which had the greatest variety and concentrations of contaminants in 2001, also had tadpoles that experienced the greatest mortality, slowest developmental rates and lowest cholinesterase activities. Yosemite and Sequoia tadpoles and metamorphs had greater genotoxicity than those in Lassen during 2001, as determined by flow cytometry. In 2001 tadpoles at Yosemite had a significantly higher rate of malformations, characterized as hemimelia (shortened femurs), than those at the other two parks but no significant differences were observed in 2002. Fewer differences in contaminant types and concentrations existed among parks during 2002 compared to 2001. In 2002 Sequoia tadpoles had higher mortality and slower developmental rates but there was no difference among parks in cholinesterase activities. Although concentrations of most contaminants were below known lethal concentrations, simultaneous exposure to multiple chemicals and other stressors may have resulted in lethal and sublethal effects. PMID:25381462

Sparling, Donald W; Bickham, John; Cowman, Deborah; Fellers, Gary M; Lacher, Thomas; Matson, Cole W; McConnell, Laura

2014-11-01

166

Effects of the glyphosate-based herbicide Roundup WeatherMax® on metamorphosis of wood frogs (Lithobates sylvaticus) in natural wetlands.  

PubMed

Amphibian tadpoles develop in aquatic environments where they are susceptible to the effects of pesticides and other environmental contaminants. Glyphosate-based herbicides are currently the most commonly used herbicide in the world and have been shown to affect survival and development of tadpoles under laboratory and mesocosm conditions. In the present study, whole wetland manipulations were used to determine if exposure to an agriculturally relevant application of Roundup WeatherMax(®), a herbicide formulation containing the potassium salt of glyphosate and an undisclosed surfactant, influences the development of wood frog tadpoles (Lithobates sylvaticus) under natural conditions. Wetlands were divided in half with an impermeable curtain so that each wetland contained a treatment and control side. Tadpoles were exposed to two pulses of this herbicide at an environmentally realistic concentration (ERC, 0.21 mg acid equivalent (a.e.)/L) and the predicted maximum environmental concentration (PMEC, 2.89 mg a.e./L), after which abundance, growth, development, and mRNA levels of genes involved in tadpole metamorphosis were measured. Results present little evidence that exposure to this herbicide affects abundance, growth and development of wood frog tadpoles. As part of the Long-term Experimental Wetlands Area (LEWA) project, this research demonstrates that typical agricultural use of Roundup WeatherMax(®) poses minimal risk to larval amphibian development. However, our gene expression data (mRNA levels) suggests that glyphosate-based herbicides have the potential to alter hormonal pathways during tadpole development. PMID:23751794

Lanctôt, C; Robertson, C; Navarro-Martín, L; Edge, C; Melvin, S D; Houlahan, J; Trudeau, V L

2013-09-15

167

Reference: Bid. Bull. 194: 132-142. (April, 1998) Role of Chemical Inducers in Larval Metamorphosis  

E-print Network

Metamorphosis of Queen Conch, Strombus gigas Linnaeus: Relationship to Other Marine Invertebrate Systems ANNE A of metamorphosis in many marine invertebrate larvae. In the queen conch, Strombus gigas Linnaeus, larval in conch nursery grounds; these species include the foliose rhodophyte Laurencia poitei (Lamouroux

Boettcher, Anne

168

Energetic loads and informational entropy during insect metamorphosis: Measuring structural variability and self-organization  

Microsoft Academic Search

In this work an information theory approach is presented for measuring structural variability during insect metamorphosis. Following a self-organizational perspective, the underlying assumption is that an insect pupa is a cybernetic bio-system, which displays a homeostatic control during its metamorphosis. The description of structural variability was based on biochemical data (lipids, glycogen, carbohydrates and proteins) analysed at different time intervals

Petros T. Damos; Nikos T. Papadopoulos; Alexandros Rigas; Matilda Savopoulou-Soultani

2011-01-01

169

The role of reduced oxygen in the developmental physiology of growth and metamorphosis initiation in Drosophila  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rearing oxygen level is known to affect final body size in a variety of insects, but the physiological mechanisms by which oxygen affects size are incompletely understood. In Manduca and Drosophila, the larval size at which metamorphosis is initiated largely determines adult size, and metamorphosis ...

170

Survival of olfactory memory through metamorphosis in the fly Musca domestica  

Microsoft Academic Search

Metamorphosis in the fly (Musca domestica) involves extensive lysis, neurogenesis and reorganization of neural tissue. Despite this, two experiments are reported which show aspects of larval memory persist into the adult form. Experimental larvae were reared in sawdust scented with aversive odours (mint or geraniol). Control larvae were reared on plain sawdust. In blind post-metamorphosis testing using a Y maze,

Steve Ray

1999-01-01

171

Growth and Partial Metamorphosis of Imaginal Disks of the Greater Wax Moth, Galleria mellonella, in vitro  

Microsoft Academic Search

THE most important of the problems of insect metamorphosis is the nature of the action of ecdysone. There is a particular lack of knowledge of the stages between the initiation of metamorphosis by ecdysone and the final differentiation into the adult. Experiments on the action of pure ecdysone in vitro have been conducted with systems which respond in a limited

H. Oberlander; L. Fulco

1967-01-01

172

The marine bacterium Alteromonas espejiana induces metamorphosis of the hydroid Hydractinia echinata  

Microsoft Academic Search

The marine hydroid Hydractinia echinata develops into a primary polyp from a planula larva stage. The planula does not undergo metamorphosis in sterile filtered seawater. Metamorphosis is induced by certain bacteria occurring, as a rule, on the shells of molluscs inhabited by hermit crabs of the genus Eupagurus. Bacteria were isolated from shells occupied by H. echinata, and bacterial clones

T. Leitz; T. Wagner

1993-01-01

173

Development of the digestive organ system in Japanese flounder in relation to metamorphosis and settlement  

Microsoft Academic Search

During metamorphosis and settlement the digestive system of Japanese flounder (Paralichthys olivaceus) exhibits various morphological features that include: differentiation and development of gastric glands and pyloric caeca coupled with partial degradation of the pancreas; involution of the liver; inflation of the gall bladder; and shortening of gut epithelium height. Pepsin?like enzyme activity increases markedly as metamorphosis proceeds, while trypsin?like enzyme

M. Tanaka; S. Kawai; T. Seikai; J. S. Burke

1996-01-01

174

Chironomidae bloodworms larvae as aquatic amphibian food.  

PubMed

Different species of chironomids larvae (Diptera: Chironomidae) so-called bloodworms are widely distributed in the sediments of all types of freshwater habitats and considered as an important food source for amphibians. In our study, three species of Chironomidae (Baeotendipes noctivagus, Benthalia dissidens, and Chironomus riparius) were identified in 23 samples of larvae from Belgium, Poland, Russia, and Ukraine provided by a distributor in Belgium. We evaluated the suitability of these samples as amphibian food based on four different aspects: the likelihood of amphibian pathogens spreading, risk of heavy metal accumulation in amphibians, nutritive value, and risk of spreading of zoonotic bacteria (Salmonella, Campylobacter, and ESBL producing Enterobacteriaceae). We found neither zoonotic bacteria nor the amphibian pathogens Ranavirus and Batrachochytrium dendrobatidis in these samples. Our data showed that among the five heavy metals tested (Hg, Cu, Cd, Pb, and Zn), the excess level of Pb in two samples and low content of Zn in four samples implicated potential risk of Pb accumulation and Zn inadequacy. Proximate nutritional analysis revealed that, chironomidae larvae are consistently high in protein but more variable in lipid content. Accordingly, variations in the lipid: protein ratio can affect the amount and pathway of energy supply to the amphibians. Our study indicated although environmentally-collected chironomids larvae may not be vectors of specific pathogens, they can be associated with nutritional imbalances and may also result in Pb bioaccumulation and Zn inadequacy in amphibians. Chironomidae larvae may thus not be recommended as single diet item for amphibians. PMID:24535989

Fard, Mojdeh Sharifian; Pasmans, Frank; Adriaensen, Connie; Laing, Gijs Du; Janssens, Geert Paul Jules; Martel, An

2014-01-01

175

Metabolomic insights into system-wide coordination of vertebrate metamorphosis  

PubMed Central

Background After completion of embryogenesis, many organisms experience an additional obligatory developmental transition to attain a substantially different juvenile or adult form. During anuran metamorphosis, the aquatic tadpole undergoes drastic morphological changes and remodelling of tissues and organs to become a froglet. Thyroid hormones are required to initiate the process, but the mechanism whereby the many requisite changes are coordinated between organs and tissues is poorly understood. Metabolites are often highly conserved biomolecules between species and are the closest reflection of phenotype. Due to the extensive distribution of blood throughout the organism, examination of the metabolites contained therein provides a system-wide overview of the coordinated changes experienced during metamorphosis. We performed an untargeted metabolomic analysis on serum samples from naturally-metamorphosing Rana catesbeiana from tadpoles to froglets using ultraperformance liquid chromatography coupled to a mass spectrometer. Total and aqueous metabolite extracts were obtained from each serum sample to select for nonpolar and polar metabolites, respectively, and selected metabolites were validated by running authentic compounds. Results The majority of the detected metabolites (74%) showed statistically significant abundance changes (padj?metamorphosis identifying fundamental pathways involved in the coordination of this important developmental process and paves the way for metabolomic studies on other metamorphic systems including fish and insects. PMID:24495308

2014-01-01

176

The Life of the Smooth Newt (Triturus vulgaris) after Metamorphosis  

Microsoft Academic Search

Abstract. After metamorphosis.,smooth,or common,newts (Tritltrus vulgtzris vltlgaris [Linn]) dis- perse on land. where,they live as juveniles,before,returning,to the water as breeding,adults. The population,age-structure was,obtained,by dissecting,the standard,length frequency,distribution. a procedure which is justified in the text. Juveniles have an uncomplicated age-structure, the nurnber of individuals in successively,later age-classes being reduced,by mortality and by recruitment,to the adult population. Among adult newts, the most

Graham Bell

2008-01-01

177

Distribution Patterns of Lentic-Breeding Amphibians in  

E-print Network

Distribution Patterns of Lentic-Breeding Amphibians in Relation to Ultraviolet Radiation Exposure amphibian population. This hypothesis has received support from laboratory and field experi- ments showing whether UV-B is influencing the distribution of amphibian populations. We compared patterns of amphibian

Knapp, Roland

178

Herpetological Review 44(2), 2013 254 AMPHIBIAN DISEASES  

E-print Network

Herpetological Review 44(2), 2013 254 AMPHIBIAN DISEASES Herpetological Review, 2013, 44(2), 254­257. © 2013 by Society for the Study of Amphibians and Reptiles Amphibian Chytrid Fungus Confirmed in Endemic al. 2004), the presence of the pathogen and its potential role in amphibian declines in West

Zamudio, Kelly R.

179

First Evidence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Hong Kong Amphibian Trade  

PubMed Central

The emerging infectious amphibian diseases caused by amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranaviruses are responsible for global amphibian population declines and extinctions. Although likely to have been spread by a variety of activities, transcontinental dispersal appears closely associated with the international trade in live amphibians. The territory of Hong Kong reports frequent, high volume trade in amphibians, and yet the presence of Bd and ranavirus have not previously been detected in either traded or free-ranging amphibians. In 2012, a prospective surveillance project was conducted to investigate the presence of these pathogens in commercial shipments of live amphibians exported from Hong Kong International Airport. Analysis of skin (Bd) and cloacal (ranavirus) swabs by quantitative PCR detected pathogen presence in 31/265 (11.7%) and in 105/185 (56.8%) of amphibians, respectively. In addition, the water in which animals were transported tested positive for Bd, demonstrating the risk of pathogen pollution by the disposal of untreated wastewater. It is uncertain whether Bd and ranavirus remain contained within Hong Kong’s trade sector, or if native amphibians have already been exposed. Rapid response efforts are now urgently needed to determine current pathogen distribution in Hong Kong, evaluate potential trade-associated exposure to free-ranging amphibians, and identify opportunities to prevent disease establishment. PMID:24599268

Kolby, Jonathan E.; Smith, Kristine M.; Berger, Lee; Karesh, William B; Preston, Asa; Pessier, Allan P.; Skerratt, Lee F.

2014-01-01

180

First evidence of amphibian chytrid fungus (Batrachochytrium dendrobatidis) and ranavirus in Hong Kong amphibian trade.  

PubMed

The emerging infectious amphibian diseases caused by amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranaviruses are responsible for global amphibian population declines and extinctions. Although likely to have been spread by a variety of activities, transcontinental dispersal appears closely associated with the international trade in live amphibians. The territory of Hong Kong reports frequent, high volume trade in amphibians, and yet the presence of Bd and ranavirus have not previously been detected in either traded or free-ranging amphibians. In 2012, a prospective surveillance project was conducted to investigate the presence of these pathogens in commercial shipments of live amphibians exported from Hong Kong International Airport. Analysis of skin (Bd) and cloacal (ranavirus) swabs by quantitative PCR detected pathogen presence in 31/265 (11.7%) and in 105/185 (56.8%) of amphibians, respectively. In addition, the water in which animals were transported tested positive for Bd, demonstrating the risk of pathogen pollution by the disposal of untreated wastewater. It is uncertain whether Bd and ranavirus remain contained within Hong Kong's trade sector, or if native amphibians have already been exposed. Rapid response efforts are now urgently needed to determine current pathogen distribution in Hong Kong, evaluate potential trade-associated exposure to free-ranging amphibians, and identify opportunities to prevent disease establishment. PMID:24599268

Kolby, Jonathan E; Smith, Kristine M; Berger, Lee; Karesh, William B; Preston, Asa; Pessier, Allan P; Skerratt, Lee F

2014-01-01

181

Spatial and temporal expression profiles suggest the involvement of gelatinase A and membrane type 1 matrix metalloproteinase in amphibian metamorphosis  

Microsoft Academic Search

The matrix metalloproteinases (MMPs) are a family of proteases capable of degrading various components of the extracellular\\u000a matrix (ECM). Among them, the membrane type MMP–1 (MT1–MMP) has been shown to participate in the activation of MMP gelatinase\\u000a A (GelA), suggesting that they may function together in development and pathogenesis. Here, we have investigated the spatiotemporal\\u000a expression profiles of Xenopus laevis

Takashi Hasebe; Rebecca Hartman; Hiroki Matsuda; Yun-Bo Shi

2006-01-01

182

Sperm storage in caecilian amphibians  

PubMed Central

Background Female sperm storage has evolved independently multiple times among vertebrates to control reproduction in response to the environment. In internally fertilising amphibians, female salamanders store sperm in cloacal spermathecae, whereas among anurans sperm storage in oviducts is known only in tailed frogs. Facilitated through extensive field sampling following historical observations we tested for sperm storing structures in the female urogenital tract of fossorial, tropical caecilian amphibians. Findings In the oviparous Ichthyophis cf. kohtaoensis, aggregated sperm were present in a distinct region of the posterior oviduct but not in the cloaca in six out of seven vitellogenic females prior to oviposition. Spermatozoa were found most abundantly between the mucosal folds. In relation to the reproductive status decreased amounts of sperm were present in gravid females compared to pre-ovulatory females. Sperm were absent in females past oviposition. Conclusions Our findings indicate short-term oviductal sperm storage in the oviparous Ichthyophis cf. kohtaoensis. We assume that in female caecilians exhibiting high levels of parental investment sperm storage has evolved in order to optimally coordinate reproductive events and to increase fitness. PMID:22672478

2012-01-01

183

Fluoxetine alters adult freshwater mussel behavior and larval metamorphosis.  

PubMed

We used acute and partial-lifecycle tests to examine the effects of the pharmaceutical fluoxetine on freshwater mussels (Unionida). In acute tests lasting 24-48 h, we determined median effective concentrations (EC50s) for fluoxetine with larval (glochidia viability) and juvenile (survival) life-stages of fatmucket (Lampsilis siliquoidea) and black sandshell (Ligumia recta). In a 28-d behavioral test we exposed brooding adult female wavy-rayed lampmussels (Lampsilis fasciola) to 0.37 and 29.3 ?g/L fluoxetine to determine effects on adult behavior (foot protrusion, mantle lure display and glochidia parturition). We also assessed the effects of 24-h exposure of 1 and 100 ?g/L fluoxetine on glochidia viability duration and metamorphosis success for the wavy-rayed lampmussel. Fluoxetine EC50s ranged from 62 ?g/L for juveniles (96 h) to 293 ?g/L for glochidia (24 h). In adults, statistically significant increases were observed in foot protrusion at 0.37 and 29.3 ?g/L fluoxetine and lure display rates at 29.3 ?g/L; glochidia parturition was not significantly affected at any test concentration. Twenty-four hour exposure of glochidia to fluoxetine did not affect viability duration, but likelihood of metamorphosis to the juvenile stage significantly increased with 1 and 100 ?g/L treatments. Our results demonstrated effects of fluoxetine to unionid mussels at concentrations less than previously reported and approaching concentrations measured in surface waters. PMID:23321069

Hazelton, Peter D; Cope, W Gregory; Mosher, Shad; Pandolfo, Tamara J; Belden, Jason B; Barnhart, M Christopher; Bringolf, Robert B

2013-02-15

184

Fibrodysplasia ossificans progressiva: mechanisms and models of skeletal metamorphosis  

PubMed Central

Fibrodysplasia ossificans progressiva (FOP; MIM #135100) is a debilitating genetic disorder of connective tissue metamorphosis. It is characterized by malformation of the great (big) toes during embryonic skeletal development and by progressive heterotopic endochondral ossification (HEO) postnatally, which leads to the formation of a second skeleton of heterotopic bone. Individuals with these classic clinical features of FOP have the identical heterozygous activating mutation (c.617G>A; R206H) in the gene encoding ACVR1 (also known as ALK2), a bone morphogenetic protein (BMP) type I receptor. Disease activity caused by this ACVR1 mutation also depends on altered cell and tissue physiology that can be best understood in the context of a high-fidelity animal model. Recently, we developed such a knock-in mouse model for FOP (Acvr1R206H/+) that recapitulates the human disease, and provides a valuable new tool for testing and developing effective therapies. The FOP knock-in mouse and other models in Drosophila, zebrafish, chickens and mice provide an arsenal of tools for understanding BMP signaling and addressing outstanding questions of disease mechanisms that are relevant not only to FOP but also to a wide variety of disorders associated with regenerative medicine and tissue metamorphosis. PMID:23115204

Kaplan, Frederick S.; Chakkalakal, Salin A.; Shore, Eileen M.

2012-01-01

185

Ecdysone signaling at metamorphosis triggers apoptosis of Drosophila abdominal muscles  

PubMed Central

One of the most dramatic examples of programmed cell death occurs during Drosophila metamorphosis, when most of the larval tissues are destroyed in a process termed histolysis. Much of our understanding of this process comes from analyses of salivary gland and midgut cell death. In contrast, relatively little is known about the degradation of the larval musculature. Here, we analyze the programmed destruction of the abdominal dorsal exterior oblique muscle (DEOM) which occurs during the first 24 hrs of metamorphosis. We find that ecdysone signaling through Ecdysone receptor isoform B1 is required cell autonomously for the muscle death. Furthermore, we show that the orphan nuclear receptor FTZ-F1, opposed by another nuclear receptor, HR39, plays a critical role in the timing of DEOM histolysis. Finally, we show that unlike the histolysis of salivary gland and midgut, abdominal muscle death occurs by apoptosis, and does not require autophagy. Thus, there is no set rule as to the role of autophagy and apoptosis during Drosophila histolysis. PMID:24051228

Zirin, Jonathan; Cheng, Daojun; Dhanyasi, Nagaraju; Cho, Julio; Dura, Jean-Maurice; VijayRaghavan, Krishnaswamy; Perrimon, Norbert

2013-01-01

186

Helminth and leech community structure in tadpoles and caudatan larvae of two amphibian species from Western Nebraska.  

PubMed

Currently no comparative studies exist on helminth and leech community structure among sympatric anuran tadpoles and salamander larvae. During June-August 2007-2009, we examined 50 bullfrog tadpoles, Rana catesbeiana , 50 barred tiger salamander larvae, Ambystoma mavortium , and 3 species of snails from Nevens Pond, Keith County, Nebraska for helminth and leech infections. The helminth and leech compound community of this larval amphibian assemblage consisted of at least 7 species, 4 in bullfrog tadpoles and 4 in barred tiger salamander larvae. Bullfrog tadpoles were infected with 2 species of nematodes ( Gyrinicola batrachiensis and Spiroxys sp.) and 2 types of metacercariae ( Telorchis sp. and echinostomatids), whereas barred tiger salamander larva were infected with 1 species of leech ( Placobdella picta ), 2 species of adult trematodes ( Telorchis corti and Halipegus sp.), and 1 species of an unidentified metacercaria. The component community of bullfrog tadpoles was dominated by helminths acquired through active penetration, or incidentally ingested through respiratory currents, or both, whereas the component community of larval salamanders was dominated by helminths acquired through ingestion of intermediate hosts (?² ?=? 3,455.00, P < 0.00001). Differences in amphibian larval developmental time (2-3 yr for bullfrog tadpoles versus 2-5 mo for salamander larvae), the ephemeral nature of intermediate hosts in Nevens Pond, and the ability of bullfrog tadpole to eliminate echinostome infections had significant effects on mean helminth species richness among amphibian species and years (t ?=? 12.31, P < 0.0001; t ?=? 2.09, P ?=? 0.04). Differences in herbivorous and carnivorous diet and time to metamorphosis among bullfrog tadpoles and barred tiger salamander larvae were important factors in structuring helminth communities among the larval stages of these 2 sympatric amphibian species, whereas size was important in structuring helminth and leech communities in larval salamanders, but not in bullfrog tadpoles. PMID:22059380

Rhoden, Heather R; Bolek, Matthew G

2012-04-01

187

The first antimicrobial peptide from sea amphibian.  

PubMed

The crab-eating frog, Rana cancrivora, is one of only a handful of amphibians worldwide that tolerates saline waters. It typically inhabits brackish water of mangrove forests of Southeast Asia. A large amount of antimicrobial peptides belonging to different families have been identified from skins of amphibians inhabiting freshwater. No antimicrobial peptide from sea amphibians has been reported. In this paper, we firstly reported the antimicrobial peptide and its cDNA cloning from skin secretions of the crab-eating frog R. cancrivora. The antimicrobial peptide was named cancrin with an amino acid sequence of GSAQPYKQLHKVVNWDPYG. By BLAST search, cancrin had no significant similarity to any known peptides. The cDNA encoding cancrin was cloned from the cDNA library of the skin of R. cancrivora. The cancrin precursor is composed of 68 amino acid residues including a signal peptide, acidic spacer peptide, which are similar to other antimicrobial peptide precursors from Ranid amphibians and mature cancrin. The overall structure is similar to other amphibian antimicrobial peptide precursors although mature cancrin is different from known peptides. The current results reported a new family of amphibian antimicrobial peptide and the first antimicrobial peptide from sea amphibian. PMID:17707909

Lu, Yi; Ma, Yufang; Wang, Xu; Liang, Jianguo; Zhang, Chongxin; Zhang, Keyun; Lin, Guoqing; Lai, Ren

2008-02-01

188

The effects of the amphibian chytrid fungus, insecticide exposure, and temperature on larval anuran development and survival.  

PubMed

Chytridiomycosis, a disease caused by Batrachochytrium dendrobatidis (Bd), has been implicated as a cause of amphibian declines. Susceptibility may be influenced by environmental factors that suppress the immune response. The authors conducted a laboratory study to examine the effect of temperature, insecticide exposure, and Bd exposure during larval anuran development. The authors examined the consequences of exposure to Bd, an insecticide (carbaryl or malathion), and static or fluctuating temperature (15?°C, 20?°C, 25?°C, or 15?°C to 25?°C 72-h flux) on larval development through metamorphosis of the Pacific treefrog (Pseudacris regilla). High and fluctuating temperature had negative effects on survival in the presence of Bd. Insecticides inhibited the effects of Bd; time to tail resorption of Pacific treefrogs decreased when tadpoles were exposed to carbaryl. The present study indicates that abiotic factors may play a role in the host-pathogen interactions in this system. PMID:25098758

Rumschlag, Samantha L; Boone, Michelle D; Fellers, Gary

2014-11-01

189

Leaping forward in amphibian health and nutrition.  

PubMed

The Epidemiology Working Group, a subgroup of the participants of the Disney's Animal Kingdom Workshop on "Ex situ Amphibian Medicine and Nutrition," identified a critical need to design and implement approaches that will facilitate the assessment and evaluation of factors impacting amphibian health. In this manuscript, we describe and summarize the outcomes of this workshop with regards (a) the identified gaps in knowledge, (b) identified priorities for closing these gaps, and (c) compile a list of actions to address these priorities. Four general areas of improvement were identified in relation to how measurements are currently being taken to evaluate ex situ amphibian health: nutrition, infectious diseases, husbandry, and integrated biology including genetics and endocrinology. The proposed actions that will be taken in order to address the identified gaps include: (1) identify and quantify major health issues affecting ex situ amphibian populations, (2) identify and coordinate laboratories to conduct analyses using standardized and validated protocols to measure nutritional, infectious diseases, genetic, and hormonal parameters, (3) determine in situ baseline distribution of parameters related to amphibian health, and (4) establish an inter-disciplinary research approach to target specific hypotheses related to amphibian health such as the effects of population genetics (e.g., relatedness, inbreeding) on disease susceptibility, or how environmental parameters are related to chronic stress and hormone production. We think is important to address current gaps in knowledge regarding amphibian health in order to increase the probability to succeed in addressing the issues faced by in situ and ex situ amphibians populations. We are confident that the recommendations provided in this manuscript will facilitate to address these challenges and could have a positive impact in both the health of in situ and ex situ amphibian populations, worldwide. Zoo Biol. 33:586-591, 2014. © 2014 Wiley Periodicals Inc. PMID:25279727

Olea-Popelka, Francisco; Ferrie, Gina M; Morris, Cheryl; Pessier, Allan P; Schad, Kristine; Stamper, M Andrew; Gagliardo, Ron; Koutsos, Elizabeth; Valdes, Eduardo V

2014-11-01

190

Changes in the role of the thyroid axis during metamorphosis of the Japanese eel, Anguilla japonica.  

PubMed

To clarify the role of thyroid function during metamorphosis from leptocephalus to glass eel in the Japanese eel, we examined the histology of the thyroid gland and measured whole-body concentrations of thyroid hormones, thyroxine (T4) and triiodothyronine (T3), and thyroid stimulating hormone ?-subunit TSH (TSH?) mRNA expression levels in five stages of artificially hatched eels (leptocephalus, early-metamorphosis, late-metamorphosis, glass eel, and elver). During metamorphosis, the inner colloid of thyroid follicles showed positive immunoreactivity for T4, and both T4 and T3 levels were significantly increased, whereas a small peak of TSH? mRNA level was observed at the early-metamorphosis stage. Similarly, TSH? mRNA levels were highest in the glass eel stage, and then decreased markedly in the elver stage. In contrast to TSH? mRNA expression, thyroid hormones (both T4 and T3) increased further from the glass eel to elver stages. These results indicated that thyroid function in the Japanese eel was active both during and after metamorphosis. Therefore, the thyrotropic axis may play important roles not only in metamorphosis but also in subsequent inshore or upstream migrations. PMID:24692334

Sudo, Ryusuke; Okamura, Akihiro; Kuroki, Mari; Tsukamoto, Katsumi

2014-08-01

191

Energetic loads and informational entropy during insect metamorphosis: measuring structural variability and self-organization.  

PubMed

In this work an information theory approach is presented for measuring structural variability during insect metamorphosis. Following a self-organizational perspective, the underlying assumption is that an insect pupa is a cybernetic bio-system, which displays a homeostatic control during its metamorphosis. The description of structural variability was based on biochemical data (lipids, glycogen, carbohydrates and proteins) analysed at different time intervals during the metamorphosis of Anarsia lineatella Zeller (Lepidoptera: Gelechiidae). Probabilities of biochemical variables were further treated by considering a finite countable set of progressive metamorphosis states having Markov properties at isothermal conditions (25 °C, 16:8h L:D, 65 ± 5%RH). The probabilities of the biochemical variables, as well as the related informational entropies, are affected when the system moves one step forward for each successive state. In most cases, but protein, there is some observable evidence that histolysis could be related to a decrease in informational entropy H ('disorganization of the system'), followed by a 'stable balance period' during the middle stages of metamorphosis. An initial increase in H is measured at the last stages of metamorphosis, which theoretically correspond to histogenesis ('reorganization of the system'). In this context, the temporal evolution of pupal structural variability was probabilistically quantified according to the classical information theory. The principles of the proposed holistic system are independent of its detailed dynamics and the proposed model can potentially describe part of the observable experimental data during metamorphosis of a holometabolous insect. PMID:21756920

Damos, Petros T; Papadopoulos, Nikos T; Rigas, Alexandros; Savopoulou-Soultani, Matilda

2011-10-01

192

Cardiovascular physiology and diseases of amphibians.  

PubMed

The class Amphibia includes three orders of amphibians: the anurans (frogs and toads), urodeles (salamanders, axolotls, and newts), and caecilians. The diversity of lifestyles across these three orders has accompanying differences in the cardiovascular anatomy and physiology allowing for adaptations to aquatic or terrestrial habitats, pulmonic or gill respiration, hibernation, and body elongation (in the caecilian). This article provides a review of amphibian cardiovascular anatomy and physiology with discussion of unique species adaptations. In addition, amphibians as cardiovascular animal models and commonly encountered natural diseases are covered. PMID:19131029

Heinz-Taheny, Kathleen M

2009-01-01

193

ARMI National Atlas for Amphibian Distributions  

NSDL National Science Digital Library

This site, from The Amphibian Research and Monitoring Initiative (ARMI), is a compilation of current and historic records of amphibian occurrences. The atlas is organized taxonomically. There are separate sections for frogs and toads, and salamanders and newts. The location of each species is mapped separately. The ARMI Atlas is meant to be an educational tool for people wanting to learn or teach others about amphibians. It can also serve as a reference for habitat managers and researchers, identifying areas where more research is needed, as well as providing information about research that has previously been done.

194

Checklist of Amphibian Species and Identification Guide  

NSDL National Science Digital Library

The US Geological Survey's Northern Prairie Wildlife Research Center has provided this online guide for identification of amphibians in North America north of Mexico. Checklists of all known amphibian species in North America north of Mexico are arranged both by family and species name, and by scientific name only. Many of the listed species are accompanied by photos, descriptions, and range maps. Since most of the information is accessible by scientific name, the site is best used by those users with some background knowledge of amphibians.

1997-01-01

195

Chytridiomycosis: a global threat to amphibians.  

PubMed

Chytridiomycosis, which is caused by Batrachochytrium dendrobatidis, is an emerging infectious disease of amphibians. The disease is one of the main causes of the global decline in amphibians. The aetiological agent is ubiquitous, with worldwide distribution, and affects a large number of amphibian species in several biomes. In the last decade, scientific research has substantially increased knowledge of the aetiological agent and the associated infection. However, important epidemiological aspects of the environment-mediated interactions between the aetiological agent and the host are not yet clear. The objective of the present review is to describe chytridiomycosis with regard to the major features of the aetiological agent, the host and the environment. PMID:24761737

Pereira, P L L; Torres, A M C; Soares, D F M; Hijosa-Valsero, M; Bécares, E

2013-12-01

196

Effects of delayed metamorphosis on larval survival, metamorphosis, and juvenile performance of four closely related species of tropical sea urchins (genus Echinometra).  

PubMed

We report here, the effects of extended competency on larval survival, metamorphosis, and postlarval juvenile growth of four closely related species of tropical sea urchins, Echinometra sp. A (Ea), E. mathaei (Em), Echinometra sp. C (Ec), and E. oblonga (Eo). Planktotrophic larvae of all four species fed on cultured phytoplankton (Chaetoceros gracilis) attained metamorphic competence within 22-24 days after fertilization. Competent larvae were forced to delay metamorphosis for up to 5 months by preventing them from settling in culture bottles with continuous stirring on a set of 10 rpm rotating rollers and larval survival per monthly intervals was recorded. Larval survival was highest at 24 days, when competence was attained (0 delayed period), and there were no significant differences among the four species. Larvae that had experienced a prolonged delay had reduced survival rate, metamorphosis success, and juvenile survival, but among older larvae, Em had the highest success followed by Ea, Eo, and Ec. Juveniles from larvae of all four species that metamorphosed soon after becoming competent tended to have higher growth rates (test diameter and length of spines) than juveniles from larvae that metamorphosed after a prolonged period of competence with progressively slower growth the longer the prolonged period. Despite the adverse effects of delaying metamorphosis on growth parameters, competent larvae of all four species were able to survive up to 5 months and after metamorphosis grew into 1-month-old juveniles in lab condition. Overall, delayed larvae of Em showed significantly higher larval survival, metamorphosis, and juvenile survival than Ea and Eo, while Ec showed the lowest values in these performances. Em has the most widespread distribution of these species ranging from Africa to Hawaii, while Ec probably has the most restricted distribution. Consequently, differences in distribution may be related to differences in the ability to delay metamorphosis. PMID:24624048

Rahman, M Aminur; Yusoff, Fatimah Md; Arshad, A; Uehara, Tsuyoshi

2014-01-01

197

Effects of Delayed Metamorphosis on Larval Survival, Metamorphosis, and Juvenile Performance of Four Closely Related Species of Tropical Sea Urchins (Genus Echinometra)  

PubMed Central

We report here, the effects of extended competency on larval survival, metamorphosis, and postlarval juvenile growth of four closely related species of tropical sea urchins, Echinometra sp. A (Ea), E. mathaei (Em), Echinometra sp. C (Ec), and E. oblonga (Eo). Planktotrophic larvae of all four species fed on cultured phytoplankton (Chaetoceros gracilis) attained metamorphic competence within 22–24 days after fertilization. Competent larvae were forced to delay metamorphosis for up to 5 months by preventing them from settling in culture bottles with continuous stirring on a set of 10?rpm rotating rollers and larval survival per monthly intervals was recorded. Larval survival was highest at 24 days, when competence was attained (0 delayed period), and there were no significant differences among the four species. Larvae that had experienced a prolonged delay had reduced survival rate, metamorphosis success, and juvenile survival, but among older larvae, Em had the highest success followed by Ea, Eo, and Ec. Juveniles from larvae of all four species that metamorphosed soon after becoming competent tended to have higher growth rates (test diameter and length of spines) than juveniles from larvae that metamorphosed after a prolonged period of competence with progressively slower growth the longer the prolonged period. Despite the adverse effects of delaying metamorphosis on growth parameters, competent larvae of all four species were able to survive up to 5 months and after metamorphosis grew into 1-month-old juveniles in lab condition. Overall, delayed larvae of Em showed significantly higher larval survival, metamorphosis, and juvenile survival than Ea and Eo, while Ec showed the lowest values in these performances. Em has the most widespread distribution of these species ranging from Africa to Hawaii, while Ec probably has the most restricted distribution. Consequently, differences in distribution may be related to differences in the ability to delay metamorphosis. PMID:24624048

Rahman, M. Aminur; Yusoff, Fatimah Md.; Arshad, A.; Uehara, Tsuyoshi

2014-01-01

198

Amphibian resources on the internet.  

PubMed

The use of amphibians in classrooms and research laboratories has increased, along with a corresponding increase in the amount of information about these animals on the Internet. This review is intended to aid both novices and experts in the search of such information. The bibliography of Internet resources is organized by discipline and includes general and selected species information, taxonomy, natural history, anatomy and histology, physiology, ontogeny, genetics, conservation, toxicology, medicine and surgery, sources (for animals, housing, and research tools), listservs, databases, associations, educational sources, and husbandry. For each web site, descriptive titles, web addresses, and a brief review are provided. Note that the authors of this review cannot assure the accuracy of content in these web resources. PMID:17592191

Nolan, Michael W; Smith, Stephen A

2007-01-01

199

Report of Amphibian Development Group  

NASA Technical Reports Server (NTRS)

Amphibian and fish embryos are extremely well suited for studies on pattern specification, whereas other systems (e.g., avian or mammalian) might be just as well suited for studies on differentiation or growth. Those distinctions are important for at least two reasons: (1) More precise focus regarding underlying mechanisms is called for when those distinctions are made. That facilitates the formulation of specific models or hypotheses; and (2) stress effects (i.e., the effects of weightlessness on structures (e.g., bones) which normally bear a load) are distinguished as being indirect, in contrast to direct effects of microgravity, which would be expected to act on pattern specification. That is, direct gravity effects are distinguished from indirect stress effects.

Malacinski, G.

1985-01-01

200

Amphibian responses to photoinduced toxicity of PAHs  

SciTech Connect

Amphibians are essential components of many ecosystems, yet little information exists on their sensitivity to environmental stressors. Recent evidence shows amphibian diversity is declining. Others have suggested this decline is a result of increasing ultraviolet (UV) light levels. Polycyclic aromatic hydrocarbons (PAHs) are widespread pollutants in the aquatic environment and their toxicity is increased in the presence of UV light. Embryos of two frogs (Rana pipiens and Xenopus laevis) were exposed to a PAH, fluoranthene, to evaluate amphibian responses to this common contaminant in the presence of sunlight. Hatching rate and development were measured in field and laboratory exposures at multiple concentrations and varying UV intensities. Hatching rate was relatively unaffected, while newly hatched larvae were sensitive to low (ug/L) concentrations. Response was related to both PAH concentration and UV intensity. Results suggest that PAH contamination in the aquatic environment may contribute to declines in amphibian populations.

Hatch, A.C.; Burton, G.A. Jr. [Wright State Univ., Dayton, OH (United States). Biological Sciences Dept.

1995-12-31

201

Amphibian chytridiomycosis in Japan: distribution, haplotypes and possible route of entry into Japan.  

PubMed

A serious disease of amphibians caused by the chytrid fungus Batrachochytrium dendrobatidis was first found in Japan in December 2006 in imported pet frogs. This was the first report of chytridiomycosis in Asia. To assess the risk of pandemic chytridiomycosis to Japanese frogs, we surveyed the distribution of the fungus among captive and wild frog populations. We established a nested PCR assay that uses two pairs of PCR primers to amplify the internal transcribed spacer (ITS) region of a ribosomal RNA cassette to detect mild fungal infections from as little as 0.001 pg (1 fg) of B. dendrobatidis DNA. We collected swab samples from 265 amphibians sold at pet shops, 294 bred at institutes and 2103 collected at field sites from northern to southwestern Japan. We detected infections in native and exotic species, both in captivity and in the field. Sequencing of PCR products revealed 26 haplotypes of the B. dendrobatidis ITS region. Phylogenetic analysis showed that three of these haplotypes were specific to the Japanese giant salamander (Andrias japonicus) and appeared to have established a commensal relationship with this native amphibian. Many other haplotypes were carried by alien amphibians. The highest genetic diversity of B. dendrobatidis was found in the American bullfrog (Rana catesbeiana). Some strains of B. dendrobatidis appeared to be endemic to Japanese native amphibians, but many alien strains are being introduced into Japan via imported amphibians. To improve chytridiomycosis risk management, we must consider the risk of B. dendrobatidis changing hosts as a result of anthropogenic disturbance of the host-specific distribution of the fungus. PMID:19840263

Goka, Koichi; Yokoyama, Jun; Une, Yumi; Kuroki, Toshiro; Suzuki, Kazutaka; Nakahara, Miri; Kobayashi, Arei; Inaba, Shigeki; Mizutani, Tomoo; Hyatt, Alex D

2009-12-01

202

Amphibians and Reptiles of Los Alamos County  

SciTech Connect

Recent studies have shown that amphibians and reptiles are good indicators of environmental health. They live in terrestrial and aquatic environments and are often the first animals to be affected by environmental change. This publication provides baseline information about amphibians and reptiles that are present on the Pajarito Plateau. Ten years of data collection and observations by researchers at Los Alamos National Laboratory, the University of New Mexico, the New Mexico Department of Game and Fish, and hobbyists are represented.

Teralene S. Foxx; Timothy K. Haarmann; David C. Keller

1999-10-01

203

Heterochrony in a complex world: disentangling environmental processes of facultative paedomorphosis in an amphibian.  

PubMed

Heterochrony, the change in the rate or timing of development between ancestors and their descendants, plays a major role in evolution. When heterochrony produces polymorphisms, it offers the possibility to test hypotheses that could explain its success across environments. Amphibians are particularly suitable to exploring these questions because they express complex life cycles (i.e. metamorphosis) that have been disrupted by heterochronic processes (paedomorphosis: retention of larval traits in adults). The large phenotypic variation across populations suggests that more complex processes than expected are operating, but they remain to be investigated through multivariate analyses over a large range of natural populations across time. In this study, we compared the likelihood of multiple potential environmental determinants of heterochrony. We gathered data on the proportion of paedomorphic and metamorphic palmate newts (Lissotriton helveticus) across more than 150 populations during 10 years and used an information-theoretic approach to compare the support of multiple potential processes. Six environmental processes jointly explained the proportion of paedomorphs in populations: predation, water availability, dispersal limitation, aquatic breathing, terrestrial habitat suitability and antipredator refuges. Analyses of variation across space and time supported models based on the advantage of paedomorphosis in favourable aquatic habitats. Paedomorphs were favoured in deep ponds, in conditions favourable to aquatic breathing (high oxygen content), with lack of fish and surrounded by suitable terrestrial habitat. Metamorphs were favoured by banks allowing easy dispersal. These results indicate that heterochrony relies on complex processes involving multiple ecological variables and exemplifies why heterochronic patterns occur in contrasted environments. On the other hand, the fast selection of alternative morphs shows that metamorphosis and paedomorphosis developmental modes could be easily disrupted in natural populations. PMID:24180255

Denoël, Mathieu; Ficetola, Gentile F

2013-11-01

204

Emerging infectious disease as a proximate cause of amphibian mass mortality.  

PubMed

A newly discovered infectious disease of amphibians, chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis, is implicated in population declines and possible extinctions throughout the world. The purpose of our study was to examine the effects of B. dendrobatidis on the mountain yellow-legged frog (Rana muscosa) in the Sierra Nevada of California (USA). We (1) quantified the prevalence and incidence of B. dendrobatidis through repeat surveys of several hundred R. muscosa populations in the southern Sierra Nevada; (2) described the population-level effects of B. dendrobatidis on R. muscosa population abundance; and (3) compared the mortality rates of infected and uninfected R. muscosa individuals from pre- through post-metamorphosis using both laboratory and field experiments. Mouthpart inspections conducted in 144 and 132 R. muscosa populations in 2003 and 2004, respectively, indicated that 19% of R. muscosa populations in both years showed indications of chytridiomycosis. Sixteen percent of populations that were uninfected in 2003 became infected by 2004. Rana muscosa population sizes were reduced by an average of 88% following B. dendrobatidis outbreaks at six sites, but at seven B. dendrobatidis-negative sites, R. muscosa population sizes increased by an average of 45% over the same time period. In the laboratory, all infected R. muscosa developed fatal chytridiomycosis after metamorphosis, while all uninfected individuals remained healthy. In the field experiment in which R. muscosa tadpoles were caged at infected and uninfected sites, 96% of the individuals that metamorphosed at infected sites died vs. 5% at the uninfected sites. These studies indicate that chytridiomycosis causes high mortality in post-metamorphic R. muscosa, that this emerging disease is the proximate cause of numerous observed R. muscosa population declines, and that the disease threatens this species with extirpation at numerous sites in California's Sierra Nevada. PMID:16922318

Rachowicz, Lara J; Knapp, Roland A; Morgan, Jess A T; Stice, Mary J; Vredenburg, Vance T; Parker, John M; Briggs, Cheryl J

2006-07-01

205

Centralspindlin is required for thorax development during Drosophila metamorphosis.  

PubMed

Epithelial morphogenesis is an essential process in all metazoans during both normal development and pathological processes such as wound healing. The coordinated regulation of cell shape, cell size, and cell adhesion during the migration of epithelial sheets ultimately gives rise to the diversity of body plans among different organisms as well as the diversity of cellular structures and tissues within an organism. Metamorphosis of the Drosophila pupa is an excellent system to study these transformative events. During pupal development, the cells of the wing imaginal discs migrate dorsally and fuse to form the adult thorax. Here I show centralspindlin, a protein complex well known for its role in cytokinesis, is essential for migration of wing disc cells and proper thorax closure. I show the subcellular localization of centralspindlin is important for its function in thorax development. This study demonstrates the emerging role of centralspindlin in regulating cell migration and cell adhesion in addition to its previously known function during cytokinesis. PMID:24700509

Sfregola, Michael

2014-05-01

206

Ligand binding pocket function of drosophila USP is necessary for metamorphosis  

Technology Transfer Automated Retrieval System (TEKTRAN)

The widely accepted paradigm that epoxidized methyl farnesoates (“juvenile hormones,” JHs) are the principle sesquiterpenoid hormones regulating insect metamorphosis was assessed in Drosophila melanogaster. GC-MS analysis showed that methyl farnesoate, rather than methyl epoxyfarnesoate (= JH III), ...

207

FOOD OF YOUNG ATLANTIC MENHADEN, BREVOORTIA TYRANNUS, IN RELATION TO METAMORPHOSIS  

E-print Network

FOOD OF YOUNG ATLANTIC MENHADEN, BREVOORTIA TYRANNUS, IN RELATION TO METAMORPHOSIS BY FRED C. JUNEI of young Atlantic menhaden (B-rel'oo'rUa. tyrann'us) after their entry as larvae into estuarine nurs- eries

208

Widespread occurrence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in the southeastern USA  

USGS Publications Warehouse

From 1999 to 2006, we sampled >1200 amphibians for the fungal pathogen Batrachochytnum dendrobatidis (Bd) at 30 sites in the southeastern USA. Using histological techniques or PCR assays, we detected chytrid infection in 10 species of aquatic-breeding amphibians in 6 states. The prevalence of chytrid infection was 17.8% for samples of postmetamorphic amphibians examined using skin swab-PCR assays (n = 202 samples from 12 species at 4 sites). In this subset of samples, anurans had a much higher prevalence of infection than caudates (39.2% vs. 5.5%, respectively). Mean prevalence in ranid frogs was 40.7 %. The only infected salamanders were Notophthalmus viridescens at 3 sites. We found infected amphibians from late winter through late spring and in 1 autumn sample. Although we encountered moribund or dead amphibians at 9 sites, most mortality events were not attributed to Bd. Chytridiomycosis was established as the probable cause of illness or death in fewer than 10 individuals. Our observations suggest a pattern of widespread and subclinical infections. However, because most of the sites in our study were visited only once, we cannot dismiss the possibility that chytridiomycosis is adversely affecting some populations. Furthermore, although there is no evidence of chytrid-associated declines in our region, the presence of this pathogen is cause for concern given global climate change and other stressors. Although presence-absence surveys may still be needed for some taxa, such as bufonids, we recommend that future researchers focus on potential population-level effects at sites where Bd is now known to occur. ?? Inter-Research 2008.

Rothermel, B.B.; Walls, S.C.; Mitchell, J.C.; Dodd, C.K., Jr.; Irwin, L.K.; Green, D.E.; Vazquez, V.M.; Petranka, J.W.; Stevenson, D.J.

2008-01-01

209

2003 Blackwell Publishing Ltd. http://www.blackwellpublishing.com/journals/ddi 89 SPECIAL ISSUE: AMPHIBIAN DECLINES  

E-print Network

: AMPHIBIAN DECLINES Diversity and Distributions (2003) 9, 89­98 Blackwell Science, Ltd Global amphibian amphibians and global amphibian declines have led to public concern, particularly because amphibians? Complex interactions of several anthropogenic factors are probably at work, and understanding amphibian

Storfer, Andrew

210

Factors Affecting Larval Sea Lamprey Growth and Length at Metamorphosis in Lampricide-Treated Streams  

Microsoft Academic Search

Larval sea lampreys Petromyzon marinus in seven lampricide-treated streams were studied to assess the effects of density and abiotic factors on growth, length at metamorphosis, and age at metamorphosis. Support for density-dependent growth was not found in these streams. A linear relationship between total length and age was found for all populations. The daily growth of larvae in lampricide-treated streams

Ronald W. Griffiths; F. W. H. Beamish; B. J. Morrison; L. A. Barker

2001-01-01

211

Juvenile hormone metabolism in the larval-pupal metamorphosis of Manduca sexta  

E-print Network

JUVENILE HORMONE METABOLISM IN THE LARVAL-PUPAL METAMORPHOSIS OF MA/V DUCA SEXTA A Thesis by STEVEN PAUL SPARAGANA Submitted to the Graduate College of Texas ALM University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE MAY 19Q4 Major Subject: BIOLOGY JUVENILE HORMONE METABOLISM IN THE LARVAL-PUPAL METAMORPHOSIS OF MANDUCA SEXFA A Thesis by STEVEN PAUL SPARAGANA Approved as to style and content by: GOVINDAN BHASKARAN (CHAIRMAN) DAVID W. OWENS (MEMBER...

Sparagana, Steven Paul

1984-01-01

212

Nitric Oxide Acts as a Positive Regulator to Induce Metamorphosis of the Ascidian Herdmania momus  

PubMed Central

Marine invertebrates commonly have a biphasic life cycle in which the metamorphic transition from a pelagic larva to a benthic post-larva is mediated by the nitric oxide signalling pathway. Nitric oxide (NO) is synthesised by nitric oxide synthase (NOS), which is a client protein of the molecular chaperon heat shock protein 90 (HSP90). It is notable, then, that both NO and HSP90 have been implicated in regulating metamorphosis in marine invertebrates as diverse as urochordates, echinoderms, molluscs, annelids, and crustaceans. Specifically, the suppression of NOS activity by the application of either NOS- or HSP90-inhibiting pharmacological agents has been shown consistently to induce the initiation of metamorphosis, leading to the hypothesis that a negative regulatory role of NO is widely conserved in biphasic life cycles. Further, the induction of metamorphosis by heat-shock has been demonstrated for multiple species. Here, we investigate the regulatory role of NO in induction of metamorphosis of the solitary tropical ascidian, Herdmania momus. By coupling pharmacological treatments with analysis of HmNOS and HmHSP90 gene expression, we present compelling evidence of a positive regulatory role for NO in metamorphosis of this species, in contrast to all existing ascidian data that supports the hypothesis of NO as a conserved negative regulator of metamorphosis. The exposure of competent H. momus larvae to a NOS inhibitor or an NO donor results in an up-regulation of NOS and HSP90 genes. Heat shock of competent larvae induces metamorphosis in a temperature dependent manner, up to a thermal tolerance that approaches 35°C. Both larval/post-larval survival and the appearance of abnormal morphologies in H. momus post-larvae reflect the magnitude of up-regulation of the HSP90 gene in response to heat-shock. The demonstrated role of NO as a positive metamorphic regulator in H. momus suggests the existence of inter-specific adaptations of NO regulation in ascidian metamorphosis. PMID:24019877

Ueda, Nobuo; Degnan, Sandie M.

2013-01-01

213

Larval settlement and metamorphosis of the mussel Mytilus coruscus in response to monospecific bacterial biofilms.  

PubMed

The effects of bacterial biofilms (BFs) on larval settlement and metamorphosis of the mussel, Mytilus coruscus, were investigated in the laboratory. Of nine different isolates, Shewanella sp.1 BF induced the highest percentage of larval settlement and metamorphosis, whereas seven other isolates had a moderate inducing activity and one isolate, Pseudoalteromonas sp. 4, had a no inducing activity. The inducing activity of individual bacterial isolates was not correlated either with their phylogenetic relationship or with the surfaces from which they were isolated. Among the eight bacterial species that demonstrated inducing activity, bacterial density was significantly correlated with the inducing activity for each strain, with the exception of Vibrio sp. 1. The Shewanella sp. 1 BF cue that was responsible for inducing larval settlement and metamorphosis was further investigated. Treatment of the BFs with formalin, antibiotics, ultraviolet irradiation, heat, and ethanol resulted in a significant decrease in their inducing activities and cell survival. BF-conditioned water (CW) did not induce larval metamorphosis, but it triggered larval settlement behavior. A synergistic effect of CW with formalin-fixed Shewanella sp. 1 BF significantly promoted larval metamorphosis. Thus, a cocktail of chemical cues derived from bacteria may be necessary to stimulate larval settlement and metamorphosis in this species. PMID:23452123

Yang, Jin-Long; Shen, Pei-Jing; Liang, Xiao; Li, Yi-Feng; Bao, Wei-Yang; Li, Jia-Le

2013-01-01

214

Countryside biogeography of Neotropical reptiles and amphibians.  

PubMed

The future of biodiversity and ecosystem services depends largely on the capacity of human-dominated ecosystems to support them, yet this capacity remains largely unknown. Using the framework of countryside biogeography, and working in the Las Cruces system of Coto Brus, Costa Rica, we assessed reptile and amphibian assemblages within four habitats that typify much of the Neotropics: sun coffee plantations (12 sites), pasture (12 sites), remnant forest elements (12 sites), and a larger, contiguous protected forest (3 sites in one forest). Through analysis of 1678 captures of 67 species, we draw four primary conclusions. First, we found that the majority of reptile (60%) and amphibian (70%) species in this study used an array of habitat types, including coffee plantations and actively grazed pastures. Second, we found that coffee plantations and pastures hosted rich, albeit different and less dense, reptile and amphibian biodiversity relative to the 326-ha Las Cruces Forest Reserve and neighboring forest elements. Third, we found that the small ribbons of "countryside forest elements" weaving through farmland collectively increased the effective size of a 326-ha local forest reserve 16-fold for reptiles and 14-fold for amphibians within our 236-km2 study area. Therefore, countryside forest elements, often too small for most remote sensing techniques to identify, are contributing -95% of the available habitat for forest-dependent reptiles and amphibians in our largely human-dominated study region. Fourth, we found large and pond-reproducing amphibians to prefer human-made habitats, whereas small, stream-reproducing, and directly developing species are more dependent on forest elements. Our investigation demonstrates that tropical farming landscapes can support substantial reptile and amphibian biodiversity. Our approach provides a framework for estimating the conservation value of the complex working landscapes that constitute roughly half of the global land surface, and which are experiencing intensification pressure worldwide. PMID:24933806

Mendenhall, Chase D; Frishkoff, Luke O; Santos-Barrera, Georgina; Pacheco, Jesús; Mesfun, Eyobed; Mendoza Quijano, Fernando; Ehrlich, Paul R; Ceballos, Gerardo; Daily, Gretchen C; Pringle, Robert M

2014-04-01

215

Estimating terrestrial amphibian pesticide body burden through dermal exposure  

EPA Science Inventory

Dermal exposure presents a potentially significant but understudied route for pesticide uptake in terrestrial amphibians. Our study measured dermal uptake of pesticides of varying hydrophobicity (logKow) in frogs. Amphibians were indirectly exposed to one of five pesticide active...

216

50 CFR 17.43 - Special rules-amphibians.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 2012-10-01 false Special rules-amphibians. 17.43 Section 17.43 Wildlife and Fisheries...PLANTS Threatened Wildlife § 17.43 Special rules—amphibians. (a) San Marcos salamander (Eurycea nana )....

2012-10-01

217

50 CFR 17.43 - Special rules-amphibians.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 false Special rules-amphibians. 17.43 Section 17.43 Wildlife and Fisheries...PLANTS Threatened Wildlife § 17.43 Special rules—amphibians. (a) San Marcos salamander (Eurycea nana )....

2010-10-01

218

50 CFR 17.43 - Special rules-amphibians.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 2011-10-01 false Special rules-amphibians. 17.43 Section 17.43 Wildlife and Fisheries...PLANTS Threatened Wildlife § 17.43 Special rules—amphibians. (a) San Marcos salamander (Eurycea nana )....

2011-10-01

219

50 CFR 17.43 - Special rules-amphibians.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 2013-10-01 false Special rules-amphibians. 17.43 Section 17.43 Wildlife and Fisheries...PLANTS Threatened Wildlife § 17.43 Special rules—amphibians. (a) San Marcos salamander (Eurycea nana )....

2013-10-01

220

Physiological, Behavioral and Maternal Factors That Contribute to Size Variation in Larval Amphibian Populations  

PubMed Central

Size variance among similarly aged individuals within populations is a pattern common to many organisms that is a result of interactions between intrinsic and extrinsic traits of individuals. While genetic and maternal effects, as well as physiological and behavioral traits have been shown to contribute to size variation in animal populations, teasing apart the influence of such factors on individual growth rates remain a challenge. Furthermore, tracing the effects of these interactions across life stages and in shaping adult phenotypes also requires further exploration. In this study we investigated the relationship between genetics, hatching patterns, behaviors, neuroendocrine stress axis activity and variance in growth and metamorphosis among same-aged larval amphibians. Through parallel experiments we found that in the absence of conspecific interactions, hatch time and to a lesser extent egg clutch identity (i.e. genetics and maternal effects) influenced the propensity for growth and development in individual tadpoles and determined metamorphic traits. Within experimental groups we found that variance in growth rates was associated with size-dependent foraging behaviors and responses to food restriction. We also found an inverse relationship between glucocorticoid (GC) hormone levels and body mass and developmental stage among group-reared tadpoles, which suggests that GC expression plays a role in regulating differing within-population growth trajectories in response to density-dependent conditions. Taken together these findings suggest that factors that influence hatching conditions can have long-term effects on growth and development. These results also raise compelling questions regarding the extent to which maternal and genetic factors influence physiological and behavioral profiles in amphibians. PMID:24143188

Warne, Robin W.; Kardon, Adam; Crespi, Erica J.

2013-01-01

221

Thyroid hormone and retinoid X receptor function and expression during sea lamprey (Petromyzon marinus) metamorphosis.  

PubMed

Sea lampreys (Petromyzon marinus) are members of the ancient class Agnatha and undergo a metamorphosis that transforms blind, sedentary, filter-feeding larvae into free-swimming, parasitic juveniles. Thyroid hormones (THs) appear to be important for lamprey metamorphosis, however, serum TH concentrations are elevated in the larval phase, decline rapidly during early metamorphosis and remain low until metamorphosis is complete; these TH fluctuations are contrary to those of other metamorphosing vertebrates. Moreover, thyroid hormone synthesis inhibitors (goitrogens) induce precocious metamorphosis and exogenous TH treatments disrupt natural metamorphosis in P. marinus. Given that THs exert their effects by binding to TH nuclear receptors (TRs) that often act as heterodimers with retinoid X receptors (RXRs), we cloned and characterized these receptors from P. marinus and examined their expression during metamorphosis. Two TRs (PmTR1 and PmTR2) and three RXRs (PmRXRs) were isolated from P. marinus cDNA. Phylogenetic analyses group the PmTRs together on a branch prior to the gnathostome TR?/? split. The three RXRs also group together, but our data indicated that these transcripts are most likely either allelic variants of the same gene locus, or the products of a lamprey-specific duplication event. Importantly, these P. marinus receptors more closely resemble vertebrate as opposed to invertebrate chordate receptors. Functional analysis revealed that PmTR1 and PmTR2 can activate transcription of TH-responsive genes when treated with nanomolar concentrations of TH and they have distinct pharmacological profiles reminiscent of vertebrate TR? and TR?, respectively. Also similar to other metamorphosing vertebrates, expression patterns of the PmTRs during lamprey metamorphosis suggest that PmTR1 has a dynamic, tissue-specific expression pattern that correlates with tissue morphogenesis and biochemical changes and PmTR2 has a more uniform expression pattern. This TR expression data suggests that THs, either directly or via a metabolite, may function to positively modulate changes at the tissue or organ levels during lamprey metamorphosis. Collectively the results presented herein support the hypothesis that THs have a dual functional role in the lamprey life cycle whereby high levels promote larval feeding, growth and lipogenesis and low levels promote metamorphosis. PMID:24907629

Manzon, Lori A; Youson, John H; Holzer, Guillaume; Staiano, Leopoldo; Laudet, Vincent; Manzon, Richard G

2014-08-01

222

Aquatic eutrophication promotes pathogenic infection in amphibians  

PubMed Central

The widespread emergence of human and wildlife diseases has challenged ecologists to understand how large-scale agents of environmental change affect host–pathogen interactions. Accelerated eutrophication of aquatic ecosystems owing to nitrogen and phosphorus enrichment is a pervasive form of environmental change that has been implicated in the emergence of diseases through direct and indirect pathways. We provide experimental evidence linking eutrophication and disease in a multihost parasite system. The trematode parasite Ribeiroia ondatrae sequentially infects birds, snails, and amphibian larvae, frequently causing severe limb deformities and mortality. Eutrophication has been implicated in the emergence of this parasite, but definitive evidence, as well as a mechanistic understanding, have been lacking until now. We show that the effects of eutrophication cascade through the parasite life cycle to promote algal production, the density of snail hosts, and, ultimately, the intensity of infection in amphibians. Infection also negatively affected the survival of developing amphibians. Mechanistically, eutrophication promoted amphibian disease through two distinctive pathways: by increasing the density of infected snail hosts and by enhancing per-snail production of infectious parasites. Given forecasted increases in global eutrophication, amphibian extinctions, and similarities between Ribeiroia and important human and wildlife pathogens, our results have broad epidemiological and ecological significance. PMID:17893332

Johnson, Pieter T. J.; Chase, Jonathan M.; Dosch, Katherine L.; Hartson, Richard B.; Gross, Jackson A.; Larson, Don J.; Sutherland, Daniel R.; Carpenter, Stephen R.

2007-01-01

223

A COLLECTION OF AMPHIBIANS AND REPTILES FROM HILLY EASTERN CAMBODIA  

Microsoft Academic Search

The first amphibian and reptile collection is reported from hilly eastern Cambodia since Henri Mouhot's work in 1859. The collection contains 30 species of amphibians and 42 species of reptiles. Leptobrachium mouhoti, new species, and Ophryophryne synoria, new species, are described. Of the remaining collection, 11 species of amphibians (39.3%) and seven species of snakes (33.3%) are reported from Cambodia

Bryan L. Stuart; Ko Sok; Thy Neang

224

A Conservation Strategy for the Amphibians of Madagascar  

E-print Network

A Conservation Strategy for the Amphibians of Madagascar Monografie del Museo Regionale di Scienze,3 , Miguel VENCES4 Towards understanding the spatial pattern of amphibian diversity in Madagascar ABSTRACT We in Madagascar based on a comprehensive database of specimen and locality data records for Malagasy amphibians

Vences, Miguel

225

ORIGINAL ARTICLE Co-habiting amphibian species harbor unique skin  

E-print Network

ORIGINAL ARTICLE Co-habiting amphibian species harbor unique skin bacterial communities in wild four pond habitats in Colorado, USA, where multiple amphibian species were present. In total, 32 amphibian individuals were sampled from three different species including northern leopard frogs (Lithobates

Fierer, Noah

226

Macroparasite Infections of Amphibians: What Can They Tell Us?  

E-print Network

Macroparasite Infections of Amphibians: What Can They Tell Us? Janet Koprivnikar,1 David J in drivers of amphibian microparasite infections and the resulting consequences, com- paratively little research has addressed such questions for amphibian macroparasites. What work has been done in this area

Johnson, Pieter

227

Evaluating the links between climate, disease spread, and amphibian declines  

E-print Network

Evaluating the links between climate, disease spread, and amphibian declines Jason R. Rohra,1 propelled the Earth into its sixth mass extinction event and amphibians, the most threatened of all vertebrate taxa, are at the forefront. Many of the worldwide amphibian declines have been caused

Rohr, Jason

228

Amphibian diversity: Decimation by disease Pieter T. J. Johnson*  

E-print Network

Amphibian diversity: Decimation by disease Pieter T. J. Johnson* Center for Limnology, University and dramatic losses of amphibian populations and species rep- resent the deadly intersection between these issues (1), as illustrated by the work of Lips et al. (2) in this issue of PNAS. Amphibians are one

Horton, Tom

229

Amphibian intersex in suburban landscapes ADRIANNE P. SMITS,1  

E-print Network

Amphibian intersex in suburban landscapes ADRIANNE P. SMITS,1 DAVID K. SKELLY,2, AND SUSAN R Citation: Smits, A. P., D. K. Skelly, and S. R. Bolden. 2014. Amphibian intersex in suburban landscapes abnormalities have been discovered in wild amphibian populations of multiple species and in a variety of regions

Skelly, David Kiernan

230

Biology 472 Spring 2009 Biology of Amphibians and Reptiles  

E-print Network

Biology 472 Spring 2009 1 Biology of Amphibians and Reptiles Dr. Kate Jackson Office: Science 200 E Encyclopedia of Reptiles and Amphibians. Oxford University Press. (2) Stebbins, R. and R. T. Peterson. 2003. A Field Guide to Western Reptiles and Amphibians. Peterson Field Guides. Houghton Mifflin. (3) Powell, et

Jackson, Kate

231

The Invasion of Exotic Reptiles and Amphibians in Florida  

E-print Network

The Invasion of Exotic Reptiles and Amphibians in Florida Institute of Food and Agricultural of reptiles and amphibians are strikingly out of balance as a result of nonnative invasions. The state has more introduced species of reptiles and amphibians living and breeding in the wild than anywhere else

Mazzotti, Frank

232

Amphibians as Indicators of Headwater Processes in Northern California Forests  

E-print Network

Amphibians as Indicators of Headwater Processes in Northern California Forests: What Are They Telling Us and Why Should We Listen?1 Hartwell H. Welsh, Jr.2 Amphibians are recognized health. Our research on headwater amphibians in the Klamath-Siskiyou and North Coast Bioregions spans

Standiford, Richard B.

233

erhaps our fascination with frogs and other amphibians starts in  

E-print Network

P erhaps our fascination with frogs and other amphibians starts in childhood, with the discovery of the overall condition of the environment. Amphibians are valuable as gauges of the planet�s health for a few amphibians sample many parts of the environment, their health re�ects the combined eÝects of many separate

Wake, David B.

234

BIOACCUMULATION AND MATERNAL TRANSFER OF MERCURY AND SELENIUM IN AMPHIBIANS  

E-print Network

BIOACCUMULATION AND MATERNAL TRANSFER OF MERCURY AND SELENIUM IN AMPHIBIANS CHRISTINE M. BERGERON November 2009) Abstract--Amphibian population declines have been documented worldwide and environmental amphibian populations. Mercury (Hg) is of particular concern due to its ubiquity in the environment, known

Hopkins, William A.

235

Climate change implicated in amphibian and lizard declines  

E-print Network

Climate change implicated in amphibian and lizard declines David B. Wake* Museum of Vertebrate Amphibian Population Task Force, organized in 1991, served as a conduit for information arriving from many. Many amphibian biologists, especially those in apparently unaffected areas, were dubious and sus

Wake, David B.

236

H-02 CONSTRUCTED WETLAND STUDIES AMPHIBIANS AND PLANTS  

E-print Network

H-02 CONSTRUCTED WETLAND STUDIES AMPHIBIANS AND PLANTS FY-2009 ANNUAL REPORT Savannah River Ecology ................................................................................................. 4 Chapter II Amphibian and Reptile Use of the H-02 Wetland .................................... 5 ............................................................................................... 27 Chapter III Vegetation Community of the H-02 Wetlands: Importance to Amphibians

Georgia, University of

237

Responses of Aquatic and Streamside Amphibians to Timber Harvest  

E-print Network

Responses of Aquatic and Streamside Amphibians to Timber Harvest: A Review R. Bruce Bury and Paul Stephen Corn Abstract Stream-dwelling amphibians, which can be the dominant vertebrates of small from logging activities. Critical needs exist to define the ecological requirements of amphibians

238

Spatial network structure and amphibian persistence in stochastic environments  

E-print Network

Spatial network structure and amphibian persistence in stochastic environments Miguel A. Fortuna1, which are used as breeding sites by several amphibian species. We investigate how the structural properties of the spatial network change as a function of the amphibian dispersal distance and the hydric

Fortuna, Miguel A.

239

Original Article Using amphibians in laboratory studies: precautions against  

E-print Network

Original Article Using amphibians in laboratory studies: precautions against the emerging is by far the most widely used amphibian species in laboratories. In the wild, X. laevis is an asymptomatic Batrachochytrium dendrobatidis (Bd), which has devastating effects on wild amphibian populations around the world

Schmeller, Dirk S.

240

A Conservation Strategy for the Amphibians of Madagascar  

E-print Network

A Conservation Strategy for the Amphibians of Madagascar Monografie del Museo Regionale di Scienze of Braunschweig, Braunschweig. Ché WELDON1 , Louis DU PREEZ1 , Miguel VENCES2 Lack of detection of the amphibian chytridiomycosis can have catastrophic effects on amphibian populations leading to declines and even extinctions

Vences, Miguel

241

Use of Amphibians as Indicators of Ecosystem Restoration Success1  

E-print Network

CIR 1484 Use of Amphibians as Indicators of Ecosystem Restoration Success1 Ken G. Rice, Frank J. Nick T. Place, dean for UF/IFAS Extension. Introduction There are 18 native amphibians in southern Florida (Figures 2 and 5). Amphibians are found in virtually all habitats from pine forests to sawgrass

Mazzotti, Frank

242

Natural History of West Indian Reptiles and Amphibians.  

E-print Network

Natural History of West Indian Reptiles and Amphibians. By Robert W. Henderson and Robert Powell names of amphibians and reptiles. ISBN: 978-0-8130- 3394-5. 2009. The West Indies is an island chain's Amphibians and Reptiles of the West Indies: Descrip- tions, Distributions, and Natural History (1991. Gaines

Rodríguez, Javier A.

243

Agrochemicals increase trematode infections in a declining amphibian species  

E-print Network

LETTERS Agrochemicals increase trematode infections in a declining amphibian species Jason R. Rohr1 R. Beasley3 Global amphibian declines have often been attributed to disease1,2 , but ignorance by augmenting snail intermediate hosts and suppressing amphibian immunity. A mesocosm experiment demonstrated

Rohr, Jason

244

Amphibian Decline or Extinction? Current Declines Dwarf Background Extinction Rate  

E-print Network

Amphibian Decline or Extinction? Current Declines Dwarf Background Extinction Rate MALCOLM L-mail: malcolm.mccallum@herpconbio.org ABSTRACT.--Amphibian declines and extinctions are critical concerns of biologists around the world. The estimated current rate of amphibian extinction is known, but how it compares

McCallum, Malcolm

245

The Decline of Amphibians in California's Great Central Valley  

Microsoft Academic Search

Declines in amphibian populations are rarely reported on the community or ecosystem level. We combined broad-scale field sampling with historical analyses of museum records to quantify amphibian de- clines in California's Great Central Valley. Overall, amphibians showed an unambiguous pattern of decline, although the intensity of decline varied both geographically and taxonomically. The greatest geographical de- cline was detected in

Robert N. Fisher; H. Bradley Shaffer

1996-01-01

246

Why Study Amphibians? They are environmental indicators-their moist,  

E-print Network

Why Study Amphibians? They are environmental indicators-their moist, permeable skins are sensitive for reproduction and larval development, and terrestrial habitats for growth and shelter. Healthy amphibian. The Southeastern Initiative The objectives of Southeast ARMI are to determine the status and trends of amphibian

Fleskes, Joe

247

Introduction Today, living amphibians comprise more than 6000  

E-print Network

Introduction Today, living amphibians comprise more than 6000 known species. In the last 11 years criteria revealed that amphibians are suffering severe declines with about 32.5 % of the known species sequences of amphibians and the compilation of a complete phylogenetic tree of the Amphibia has been

Vences, Miguel

248

WFS 433/533 AMPHIBIAN ECOLOGY AND CONSERVATION  

E-print Network

1 WFS 433/533 AMPHIBIAN ECOLOGY AND CONSERVATION Spring 2014 Instructor: Dr. Matthew Gray: The Ecology and Behavior of Amphibians, 2007 (ISBN 9780226893341) Author: Kentwood D. Wells (reserved at Pendergrass and available online) The Amphibians of Tennessee (http://utpress.org/) Authors: Matthew Niemiller

Gray, Matthew

249

H-02 CONSTRUCTED WETLAND STUDIES AMPHIBIANS AND PLANTS  

E-print Network

H-02 CONSTRUCTED WETLAND STUDIES AMPHIBIANS AND PLANTS FY-2008 ANNUAL REPORT Savannah River Ecology ................................................................................................. 4 CHAPTER II -- AMPHIBIAN AND REPTILE USE OF THE H-02 WETLAND .................................... 5 ............................................................................................... 17 CHAPTER III: VEGETATION COMMUNITY OF THE H-02 WETLANDS -- IMPORTANCE TO AMPHIBIANS

Georgia, University of

250

Measuring the Meltdown: Drivers of Global Amphibian Extinction and Decline  

E-print Network

Measuring the Meltdown: Drivers of Global Amphibian Extinction and Decline Navjot S. Sodhi1 of amphibian biodiversity. However, the relative importance of and synergies among different drivers are still poorly understood. We present the largest global analysis of roughly 45% of known amphibians (2

Sekercioglu, Cagan Hakki

251

Status and Trends of Amphibian Declines and Extinctions Worldwide  

Microsoft Academic Search

The first global assessment of amphibians provides new context to the well-publicised phenomenon of amphibian declines. Amphibians are more threatened, and are declining more rapidly, than either birds or mammals. Although many declines are due to habitat loss and over- utilization, other, unidentified processes threaten 48% of rapidly declining species, and are driving species most quickly to extinction. Declines are

Simon N. Stuart; Janice S. Chanson; Neil A. Cox; Bruce E. Young; Ana S. L. Rodrigues; Debra L. Fischman; Robert W. Waller

2004-01-01

252

Facility Design and Associated Services for the Study of Amphibians  

Microsoft Academic Search

The role of facilities and associated services for amphibians has recently undergone diversification. Amphibians tradi- tionally used as research models adjust well to captivity and thrive with established husbandry techniques. However, it is now necessary to maintain hundreds of novel amphibian species in captive breeding, conservation research, and bio- medical research programs. These diverse species have a very wide range

Robert K. Browne; R. Andrew Odum; Timothy Herman; Kevin Zippel

253

Colonization of Restored Wetlands by Amphibians in Minnesota  

Microsoft Academic Search

Twelve wetlands (7 recently restored; 5 reference) in central and southern Minnesota were monitored during the 1998 breeding season to assess colonization of recently restored wetlands by amphibians, compare the amphibian fauna to that of reference wetlands and identify important factors influencing the probability of colonization. Eight amphibian species rapidly colonized recently restored wetlands and established breeding populations. Reference wetlands

RICHARD M. LEHTINEN; SUSAN M. GALATOWITSCH

2001-01-01

254

Amphibian monitoring in the Atchafalaya Basin  

USGS Publications Warehouse

Amphibians are a diverse group of animals that includes frogs, toads, and salamanders. They are adapted to living in a variety of habitats, but most require water for at least one life stage. Amphibians have recently become a worldwide conservation concern because of declines and extinctions even in remote protected areas previously thought to be safe from the pressures of habitat loss and degradation. Amphibians are an important part of ecosystem dynamics because they can be quite abundant and serve both as a predator of smaller organisms and as prey to a suite of vertebrate predators. Their permeable skin and aquatic life history also make them useful as indicators of ecosystem health. Since 2002, the U.S. Geological Survey has been studying the frog and toad species inhabiting the Atchafalaya Basin to monitor for population declines and to better understand how the species are potentially affected by disease, environmental contaminants, and climate change.

Waddle, Hardin

2011-01-01

255

North American Reporting Center for Amphibian Malformations  

NSDL National Science Digital Library

Created in June, 1997 and funded by the US Geological Survey and Environmental Protection Agency, this site is a response to the discovery of numerous deformed amphibians (mostly frogs) in areas as widespread as Minnesota, California, and Florida. Malformations include extra or missing limbs, missing eyes, and split limbs. The site is intended to serve as a central repository for data on the type and relative frequency of such malformations throughout the US. Researchers hope to use the site to help discover the cause(s) of these deformities. The site contains a map of where malformations have been reported, background on the occurrence and possible causes of defects, numerous images of malformed amphibians, a searchable bibliography, instructions on how to report the discovery of a malformed amphibian, and links to eight related web sites. NARCAM's site also contains a toll-free number for citizen reports.

Center., Northern P.

1997-01-01

256

Emesis and space motion sickness in amphibians.  

PubMed

Amphibians possess the ability to vomit in response to a variety of stimuli that provoke emesis in mammals. Pharmacological studies have establish that the ejection of gastric contents and the basic mechanism for vomiting have been phylogenetically conserved among these tetrapods. As part of on-going comparative studies on emesis in vertebrates, we previously documented that some postmetamorphic anurans and salamander larvae experience motion-induced emesis when exposed to the provocative stimulus of parabolic aircraft flight. However, more recent experiments suggest that there are strict conditions for inducing emesis in amphibians exposed to parabolic flight and that amphibians are not as sensitive to this stimulus as mammals. Further studies on emesis in lower vertebrates may help us understand the processes that cause emesis in abnormal gravitational regimes. PMID:11542850

Naitoh, T; Yamashita, M; Izumi-Kurotani, A; Takabatake, I; Wassersug, R J

2000-01-01

257

Design of an Amphibian Exploring Robot  

NASA Astrophysics Data System (ADS)

To design and develop an amphibian exploring robot capable of operation in constrained mine environment puts a tremendous challenge to the system developers from both scientific and engineering perspective. Very few attempts have been made to fulfil these criteria of versatility in design, communication and control. The CSIR-CMERI developed amphibian subterranean robotic explorer (SR) is capable of moving over fairly rough terrain. It can swim as well as crawl over basin floor effortlessly. It is capable of operating at a maximum depth of 10m and can swim at 1 knot. A number of field trials have been carried out for performance testing of the system to ascertain its capability in underground flooded mine tunnels. This paper presents the insight on the design of an amphibian exploring robot for mine safety and disaster mitigation with special features of low power consumption vis-a-vis high mission time.

Maity, Atanu; Majumder, Somajyoti

2014-07-01

258

The relationship between the emergence of Batrachochytrium dendrobatidis, the international trade in amphibians and introduced amphibian species  

Microsoft Academic Search

Chytridiomycosis is an emerging infectious disease of amphibians caused by the chytrid Batrachochytrium dendrobatidis. The disease has been associated with global amphibian declines and species extinctions, however the principle drivers that underly the emergence of chytridiomycosis remain unclear. Current evidence suggests that the world trade in amphibians is implicated in the emergence of chytridiomycosis. Here, we review the evidence that

Matthew C. Fisher; Trenton W. J. Garner

2007-01-01

259

PRESENCE OF AMPHIBIAN CHYTRID FUNGUS BATRACHOCHYTRIUM DENDROBATIDIS AND OTHER AMPHIBIAN PATHOGENS AT WARM WATER FISH HATCHERIES IN SOUTHEASTERN NORTH AMERICA  

Microsoft Academic Search

We conducted health screenings for infectious diseases of amphibians at four warm-water fish hatcheries and one National Wildlife Refuge in the southeastern United States. We confirmed the presence of Batrachochytrium dendrobatidis (amphibian chytrid fungus) in Rana catesbeiana (American Bullfrog) from one hatchery, as well as potentially new species of microsporidian and myxozoan parasites infecting all 10 amphibian species sampled. Viruses

D. EARL GREEN; C. KENNETH DODD JR

260

USGS: Amphibian Research and Monitoring Initiative  

NSDL National Science Digital Library

The Amphibian Research and Monitoring Initiative (ARMI) was formed by the U.S. Geological Survey as a national program for amphibian conservation, research, and monitoring. The website provides background information about ARMI as well as sections on Monitoring, Research & Development, Regions & People, and Products. The Research & Development section includes information about ongoing efforts at national, regional, and local levels. The Products section links to an extensive list of publications (some of which are hyperlinked) including Journal Articles, Circulars, Reports, and more. The site also links to great resources like The ARMI Web Tool, and The ARMI National Atlas (reported on in NSDL Scout Report for the Life Sciences, May 30, 2003).

261

Nebular metamorphosis during the post-AGB phase: multiwavelength studies  

NASA Astrophysics Data System (ADS)

The processes that lead to the formation of Planetary Nebula (PN), through the short intermediate stage of pre-PN, are complex and poorly known. The biggest challenge in the study of PN formation is understanding the origin of the remarkable morphological and kinematical differences between the circumstellar envelopes (CSEs) around Asymptotic Giant Branch (AGB) stars, which result from the star mass-loss process during the AGB, and their more evolved counterparts, PPNe and PNe. While AGB CSEs expand isotropically at low velocity (about 5-15 km/s), most PPNe and PNe have clear departures from sphericity and show fast (>100 km/s) bipolar or multipolar outflows. This spectacular metamorphosis is believed to be governed by the interaction between fast, collimated post-AGB winds (or jets), and the slow AGB CSE. In this presentation, I will review these late stages of the evolution of solar type stars and will describe some common observational techniques used to characterize the different nebular components in these objects.

Sanchez Contreras, C.

2011-11-01

262

Specification of regional intestinal stem cell identity during Drosophila metamorphosis.  

PubMed

In the adult Drosophila midgut the bone morphogenetic protein (BMP) signaling pathway is required to specify and maintain the acid-secreting region of the midgut known as the copper cell region (CCR). BMP signaling is also involved in the modulation of intestinal stem cell (ISC) proliferation in response to injury. How ISCs are able to respond to the same signaling pathway in a regionally different manner is currently unknown. Here, we show that dual use of the BMP signaling pathway in the midgut is possible because BMP signals are only capable of transforming ISC and enterocyte identity during a defined window of metamorphosis. ISC heterogeneity is established prior to adulthood and then maintained in cooperation with regional signals from surrounding tissue. Our data provide a conceptual framework for how other tissues maintained by regional stem cells might be patterned and establishes the pupal and adult midgut as a novel genetic platform for identifying genes necessary for regional stem cell specification and maintenance. PMID:24700821

Driver, Ian; Ohlstein, Benjamin

2014-05-01

263

Adding infection to injury: synergistic effects of predation and parasitism on amphibian malformations.  

PubMed

We explored the importance of interactions between parasite infection and predation in driving an emerging phenomenon of conservation importance: amphibian limb malformations. We suggest that injury resulting from intraspecific predation in combination with trematode infection contributes to the frequency and severity of malformations in salamanders. By integrating field surveys and experiments, we evaluated the individual and combined effects of conspecific attack and parasite (Ribeiroia ondatrae) infection on limb development of long-toed salamanders (Ambystoma macrodactylum). In the absence of Ribeiroia, abnormalities involved missing digits, feet, or limbs and were similar to those produced by cannibalistic attack in experimental trials. At field sites that supported Ribeiroia, malformations were dominated by extra limbs and digits. Correspondingly, laboratory exposure of larval salamanders to Ribeiroia cercariae over a 30-day period induced high frequencies of malformations, including extra digits, extra limbs, cutaneous fusion, and micromelia. However, salamander limbs exposed to both injury and infection exhibited 3-5 times more abnormalities than those exposed to either factor alone. Infection also caused significant delays in limb regeneration and time-to-metamorphosis. Taken together, these results help to explain malformation patterns observed in natural salamander populations while emphasizing the importance of interactions between parasitism and predation in driving disease. PMID:16995623

Johnson, Pieter T J; Preu, Eric R; Sutherland, Daniel R; Romansic, John M; Han, Barbara; Blaustein, Andrew R

2006-09-01

264

Lethal effect and in vivo genotoxicity of profenofos to Chinese native amphibian (Rana spinosa) tadpoles.  

PubMed

Amphibian populations are decreasing in size due to environmental stressors in most areas of southern China. Pesticides are known to be a group of potential stressors to amphibians, especially in agricultural ecosystems. Profenofos, an organophosphate insecticide and acaricide, is widely used for controlling insect pests in China. The aim of this study is to evaluate the acute lethality and genotoxicity of profenofos to amphibian under controlled conditions. Results showed that profenofos was highly lethal to tadpoles of Rana spinosa, with 50% lethal concentration (LC(50)) values of 1.59, 1.14, 0.77, and 0.58 mg l(-1) at 24, 48, 72, and 96 h, respectively. DNA damage of erythrocytes was observed by alkaline single-cell gel electrophoresis assay at all tested sublethal concentrations. The study also showed, by micronucleus test, that profenofos at moderate to high sublethal concentration might have genotoxicity to the tadpole after 96 h exposure. Furthermore, based on our results, it is suggested that the alkaline single-cell gel electrophoresis assay could be used as a screening tool for biomonitoring of pesticide contamination in aquatic systems or agricultural ecosystems. PMID:20333372

Li, Xianbin; Li, Shaonan; Liu, Shaoying; Zhu, Guonian

2010-10-01

265

The state of amphibians in the United States  

USGS Publications Warehouse

More than 25 years ago, scientists began to identify unexplained declines in amphibian populations around the world. Much has been learned since then, but amphibian declines have not abated and the interactions among the various threats to amphibians are not clear. Amphibian decline is a problem of local, national, and international scope that can affect ecosystem function, biodiversity, and commerce. This fact sheet provides a snapshot of the state of the amphibians and introduces examples to illustrate the range of issues in the United States.

Muths, E.; Adams, M.J.; Grant, E.H.C.; Miller, D.; Corn, P.S.; Ball, L.C.

2012-01-01

266

Helping Your Local Amphibians (HYLA): An Internet-based Amphibian Course for Educators.  

ERIC Educational Resources Information Center

Introduces an online zoology course that was offered primarily to upper elementary and middle school teachers in which teachers were expected to take action to help the local amphibian population. (Author/YDS)

Murphy, Tony P.

2001-01-01

267

The amphibian pathogen Batrachochytrium dendrobatidis detected in a community of stream and wetland amphibians  

USGS Publications Warehouse

The amphibian chytrid fungus Batrachochytrium dendrobatidis, responsible for the potentially fatal amphibian disease chytridiomycosis, is known to occur in a large and ever increasing number of amphibian populations around the world. However, sampling has been biased towards stream- and wetland-breeding anurans, with little attention paid to stream-associated salamanders. We sampled three frog and three salamander species in the Chesapeake and Ohio Canal National Historic Park, Maryland, by swabbing animals for PCR analysis to detect DNA of B. dendrobatidis. Using PCR, we detected B. dendrobatidis DNA in both stream and wetland amphibians, and report here the first occurrence of the pathogen in two species of stream-associated salamanders. Future research should focus on mechanisms within habitats that may affect persistence and dissemination of B. dendrobatidis among stream-associated salamanders.

Grant, E.H.C.; Bailey, L.L.; Ware, J.L.; Duncan, K.C.

2008-01-01

268

Possible interrelations among environmental toxicants, amphibian development, and decline of amphibian populations.  

PubMed Central

Many amphibian populations are declining in a number of geographical locations throughout the world. In most cases, the cause or causes are unknown, but are assumed to result from man-made alterations in the environment. We review existing evidence concerning how environmental xenobiotics could contribute to declines of amphibian populations by impacting growth and development of the young. This paper examines the potential roles of toxicants in: a) affecting the susceptibility of young to disease; b) retarding growth and development of amphibian young; c) affecting the ability of larvae to avoid predation; d) affecting the development of physiological, morphological, or behavioral processes in a manner that subsequently impairs the ability of the young for future reproduction; and e) directly causing mortality of young. These issues are not well studied, and more studies are needed before the roles of environmental xenobiotics in amphibian declines are fully understood. PMID:7556018

Carey, C; Bryant, C J

1995-01-01

269

Identification of genes differentially expressed during larval molting and metamorphosis of Helicoverpa armigera  

PubMed Central

Background Larval molting and metamorphosis are important physiological processes in the life cycle of the holometabolous insect. We used suppression subtractive hybridization (SSH) to identify genes differentially expressed during larval molting and metamorphosis. Results We performed SSH between tissues from a variety of developmental stages, including molting 5th and feeding 6th instar larvae, metamorphically committed and feeding 5th instar larvae, and feeding 5th instar and metamorphically committed larvae. One hundred expressed sequence tags (ESTs) were identified and included 73 putative genes with similarity to known genes, and 27 unknown ESTs. SSH results were further characterized by dot blot, Northern blot, and RT-PCR. The expression levels of eleven genes were found to change during larval molting or metamorphosis, suggesting a functional role during these processes. Conclusion These results provide a new set of genes expressed specifically during larval molt or metamorphosis that are candidates for further studies into the regulatory mechanisms of those stage-specific genes during larval molt and metamorphosis PMID:17588272

Dong, Du-Juan; He, Hong-Juan; Chai, Lian-Qin; Jiang, Xiao-Juan; Wang, Jin-Xing; Zhao, Xiao-Fan

2007-01-01

270

Metamorphosis alters contaminants and chemical tracers in insects: implications for food webs  

USGS Publications Warehouse

Insects are integral to most freshwater and terrestrial food webs, but due to their accumulation of environmental pollutants they are also contaminant vectors that threaten reproduction, development, and survival of consumers. Metamorphosis from larvae to adult can cause large chemical changes in insects, altering contaminant concentrations and fractionation of chemical tracers used to establish contaminant biomagnification in food webs, but no framework exists for predicting and managing these effects. We analyzed data from 39 studies of 68 analytes (stable isotopes and contaminants), and found that metamorphosis effects varied greatly. ?15N, widely used to estimate relative trophic position in biomagnification studies, was enriched by 1‰ during metamorphosis, while ?13C used to estimate diet, was similar in larvae and adults. Metals and polycyclic aromatic hydrocarbons (PAHs) were predominantly lost during metamorphosis leading to 2 to 125-fold higher larval concentrations and higher exposure risks for predators of larvae compared to predators of adults. In contrast, manufactured organic contaminants (such as polychlorinated biphenyls) were retained and concentrated in adults, causing up to 3-fold higher adult concentrations and higher exposure risks to predators of adult insects. Both food web studies and contaminant management and mitigation strategies need to consider how metamorphosis affects the movement of materials between habitats and ecosystems, with special regard for aquatic-terrestrial linkages.

Kraus, Johanna M.; Walters, David; Wesner, Jeff S.; Stricker, Craig A.; Schmidt, Travis S.; Zuellig, Robert E.

2014-01-01

271

Metamorphosis alters contaminants and chemical tracers in insects: implications for food webs.  

PubMed

Insects are integral to most freshwater and terrestrial food webs, but due to their accumulation of environmental pollutants they are also contaminant vectors that threaten reproduction, development, and survival of consumers. Metamorphosis from larvae to adult can cause large chemical changes in insects, altering contaminant concentrations and fractionation of chemical tracers used to establish contaminant biomagnification in food webs, but no framework exists for predicting and managing these effects. We analyzed data from 39 studies of 68 analytes (stable isotopes and contaminants), and found that metamorphosis effects varied greatly. ?(15)N, widely used to estimate relative trophic position in biomagnification studies, was enriched by ? 1‰ during metamorphosis, while ?(13)C used to estimate diet, was similar in larvae and adults. Metals and polycyclic aromatic hydrocarbons (PAHs) were predominantly lost during metamorphosis leading to ? 2 to 125-fold higher larval concentrations and higher exposure risks for predators of larvae compared to predators of adults. In contrast, manufactured organic contaminants (such as polychlorinated biphenyls) were retained and concentrated in adults, causing up to ? 3-fold higher adult concentrations and higher exposure risks to predators of adult insects. Both food web studies and contaminant management and mitigation strategies need to consider how metamorphosis affects the movement of materials between habitats and ecosystems, with special regard for aquatic-terrestrial linkages. PMID:25136925

Kraus, Johanna M; Walters, David M; Wesner, Jeff S; Stricker, Craig A; Schmidt, Travis S; Zuellig, Robert E

2014-09-16

272

Presence of the Amphibian Chytrid Fungus Batrachochytrium dendrobatidis in Native Amphibians Exported from Madagascar  

PubMed Central

The emerging infectious disease chytridiomycosis is driven by the spread of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd), a highly virulent pathogen threatening global amphibian biodiversity. Although pandemic in distribution, previous intensive field surveys have failed to detect Bd in Madagascar, a biodiversity hotspot home to hundreds of endemic amphibian species. Due to the presence of Bd in nearby continental Africa and the ecological crisis that can be expected following establishment in Madagascar, enhanced surveillance is imperative. I sampled 565 amphibians commercially exported from Madagascar for the presence of Bd upon importation to the USA, both to assist early detection efforts and demonstrate the conservation potential of wildlife trade disease surveillance. Bd was detected in three animals via quantitative PCR: a single Heterixalus alboguttatus, Heterixalus betsileo, and Scaphiophryne spinosa. This is the first time Bd has been confirmed in amphibians from Madagascar and presents an urgent call to action. Our early identification of pathogen presence prior to widespread infection provides the necessary tools and encouragement to catalyze a swift, targeted response to isolate and eradicate Bd from Madagascar. If implemented before establishment occurs, an otherwise likely catastrophic decline in amphibian biodiversity may be prevented. PMID:24599336

Kolby, Jonathan E.

2014-01-01

273

Presence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in native amphibians exported from Madagascar.  

PubMed

The emerging infectious disease chytridiomycosis is driven by the spread of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd), a highly virulent pathogen threatening global amphibian biodiversity. Although pandemic in distribution, previous intensive field surveys have failed to detect Bd in Madagascar, a biodiversity hotspot home to hundreds of endemic amphibian species. Due to the presence of Bd in nearby continental Africa and the ecological crisis that can be expected following establishment in Madagascar, enhanced surveillance is imperative. I sampled 565 amphibians commercially exported from Madagascar for the presence of Bd upon importation to the USA, both to assist early detection efforts and demonstrate the conservation potential of wildlife trade disease surveillance. Bd was detected in three animals via quantitative PCR: a single Heterixalus alboguttatus, Heterixalus betsileo, and Scaphiophryne spinosa. This is the first time Bd has been confirmed in amphibians from Madagascar and presents an urgent call to action. Our early identification of pathogen presence prior to widespread infection provides the necessary tools and encouragement to catalyze a swift, targeted response to isolate and eradicate Bd from Madagascar. If implemented before establishment occurs, an otherwise likely catastrophic decline in amphibian biodiversity may be prevented. PMID:24599336

Kolby, Jonathan E

2014-01-01

274

Will climate change reduce the effects of a pesticide on amphibians?: partitioning effects on exposure and  

E-print Network

atrazine (0, 4, 40, and 400 mg LÃ?1 ) by quantifying growth, survival, hatching, and metamorphosis under an atrazine exposure duration that was either constant or that depended on time to metamorphosis (and thus temperature). Increasing atrazine concentrations reduced growth, delayed hatching and metamorphosis

Rohr, Jason

275

Temperature, genetic and hydroperiod effects on metamorphosis of brown frogs Rana arvalis and R. temporaria in the field  

Microsoft Academic Search

Time for metamorphosis and metamorph size of moor frogs Rana arvalis and common frogs R. temporaria were measured in 22 ponds for 1-8 years. Environmental data in these ponds were also measured. Metamorphosis of the frogs took place from the beginning of June to the beginning of August. When both species were found in one pond, the common frogs metamorphosed

Jon Loman

2002-01-01

276

Role of Chemical Inducers in Larval Metamorphosis of Queen Conch, Strombus gigas Linnaeus: Relationship to Other Marine Invertebrate Systems  

Microsoft Academic Search

Chemical cues are important in the exoge- nous and endogenous control of metamorphosis in many marine invertebrate larvae. In the queen conch, Strombus gigas Linnaeus, larval metamorphosis is induced by low molecular weight compounds associated with dominant species of red algae found in conch nursery grounds; these species include the foliose rhodophyte Laurencia poitei (Lamouroux). The responses of conch larvae

ANNE A. BOETTCHER; NANCY M. TARGETT

277

Juvenile hormone prevents 20-hydroxyecdysone-induced metamorphosis by regulating the phosphorylation of a newly identified broad protein.  

PubMed

The steroid hormone 20-hydroxyecdysone (20E) initiates insect molting and metamorphosis. By contrast, juvenile hormone (JH) prevents metamorphosis. However, the mechanism by which JH inhibits metamorphosis remains unclear. In this study, we propose that JH induces the phosphorylation of Broad isoform Z7 (BrZ7), a newly identified protein, to inhibit 20E-mediated metamorphosis in the lepidopteran insect Helicoverpa armigera. The knockdown of BrZ7 in larvae inhibited metamorphosis by repressing the expression of the 20E response gene. BrZ7 was weakly expressed and phosphorylated during larval growth but highly expressed and non-phosphorylated during metamorphosis. JH regulated the rapid phosphorylation of BrZ7 via a G-protein-coupled receptor-, phospholipase C-, and protein kinase C-triggered pathway. The phosphorylated BrZ7 bound to the 5'-regulatory region of calponin to regulate its expression in the JH pathway. Exogenous JH induced BrZ7 phosphorylation to prevent metamorphosis by suppressing 20E-related gene transcription. JH promoted non-phosphorylated calponin interacting with ultraspiracle protein to activate the JH pathway and antagonize the 20E pathway. This study reveals one of the possible mechanisms by which JH counteracts 20E-regulated metamorphosis by inducing the phosphorylation of BrZ7. PMID:25096576

Cai, Mei-Juan; Liu, Wen; Pei, Xu-Yang; Li, Xiang-Ru; He, Hong-Juan; Wang, Jin-Xing; Zhao, Xiao-Fan

2014-09-19

278

Amphibian XIS: an immersion lithography microstepper platform  

Microsoft Academic Search

Recent advances in immersion lithography have created the need for a small field microstepper to carry out the early learning necessary for next generation device application. Combined with fluid immersion, multiple-beam lithography can provide an opportunity to explore lithographic imaging at oblique propagation angles and extreme NA imaging. Using the phase preserving properties of Smith Talbot interferometry, the Amphibian XIS

Bruce W. Smith; Anatoly Bourov; Yongfa Fan; Frank Cropanese; Peter Hammond

2005-01-01

279

Class Amphibia I. General Amphibian Characteristics  

E-print Network

-interbreeding species. III. Gymnophiona - Caecilians #12;4 Caeciliaidae.--is the largest family, with about 22 genera aquatic caecilians, with four genera in South America, some to 75 cm. The posterior body is laterally different from other amphibians? Characteristics of Caecilians (built for burrowing)­ some are secondarily

Dever, Jennifer A.

280

The First Fossil Record of Caecilian Amphibians  

Microsoft Academic Search

THREE groups of amphibians are living today-frogs, salamanders and caecilians. The fossil record of frogs and salamanders is relatively poor1,2, but representatives of most groups have been discovered. For the caecilians, however, no authentic fossils have been recognized, until now. We describe here a single diagnostic vertebra from the Palaeocene of Brazil.

Richard Estes; MARVALEE H. WAKE

1972-01-01

281

Universal COI primers for DNA barcoding amphibians.  

PubMed

DNA barcoding is a proven tool for the rapid and unambiguous identification of species, which is essential for many activities including the vouchering tissue samples in the genome 10K initiative, genealogical reconstructions, forensics and biodiversity surveys, among many other applications. A large-scale effort is underway to barcode all amphibian species using the universally sequenced DNA region, a partial fragment of mitochondrial cytochrome oxidase subunit I COI. This fragment is desirable because it appears to be superior to 16S for barcoding, at least for some groups of salamanders. The barcoding of amphibians is essential in part because many species are now endangered. Unfortunately, existing primers for COI often fail to achieve this goal. Herein, we report two new pairs of primers (?, ?) that in combination serve to universally amplify and sequence all three orders of Chinese amphibians as represented by 36 genera. This taxonomic diversity, which includes caecilians, salamanders and frogs, suggests that the new primer pairs will universally amplify COI for the vast majority species of amphibians. PMID:22145866

Che, Jing; Chen, Hong-Man; Yang, Jun-Xiao; Jin, Jie-Qiong; Jiang, Ke; Yuan, Zhi-Yong; Murphy, Robert W; Zhang, Ya-Ping

2012-03-01

282

Migration and orientation in anuran amphibians  

Microsoft Academic Search

In anuran amphibians migratory behaviour is constrained by the demands of water balance and thermoregulation. Therefore, the migratory range of anurans amounts to 15 km at most. Adult anurans perform migrations, if important habitat resources (e.g. sites for reproduction, nutrition and hibernation) are spatially separated. Site fidelity to these spatial units is a common feature of most anurans. These general

Ulrich Sinsch

1990-01-01

283

Soak It Up: Understanding Amphibian Permeability  

NSDL National Science Digital Library

In this activity, learners will discover how the thin layers of amphibians' skin allow water and other chemicals to pass through it. Learners will also discover how different body coverings affect permeability. Learn why and how this affects their body, and what you can do to protect them in the wild. Thin skin is in, dirty environments are not!

Aquariums, Association O.

2009-01-01

284

Decline of a Tropical Montane Amphibian Fauna  

Microsoft Academic Search

On the basis of surveys conducted between 1991 and 1996, I report a decline of the amphibian fauna at Las Tablas, Puntarenas Province, Costa Rica. I propose that the reduction in the abundance of Atelo- pus chiriquiensis and Hyla calypsa , the presence of dead and dying individuals of six species of frogs and sala- manders, and changes in population

Karen R. Lips

1998-01-01

285

Culture of Cells from Amphibian Embryos.  

ERIC Educational Resources Information Center

Describes a method for in vitro culturing of cells from amphibian early embryos. Such cells can be used to demonstrate such properties of eukaryote cells as cell motility, adhesion, differentiation, and cell sorting into tissues. The technique may be extended to investigate other factors. (Author/JN)

Stanisstreet, Martin

1983-01-01

286

Emerging Infectious Diseases and Amphibian Population Declines  

Microsoft Academic Search

We review recent research on the pathology, ecology, and biogeography of two emerging infectious wildlife diseases, chytridiomycosis and ranaviral disease, in the context of host-parasite population biology. We examine the role of these diseases in the global decline of amphibian populations and propose hypotheses for the origins and impact of these panzootics. Finally, we discuss emerging infectious diseases as a

Peter Daszak; Lee Berger; Andrew A. Cunningham; Alex D. Hyatt; D. Earl Green; Rick Speare

1999-01-01

287

Challenges of Invasive Reptiles and Amphibians  

Microsoft Academic Search

Although worldwide distributions of many amphibians and reptiles are declining, a handful of species are spreading rapidly throughout tropical regions of the world. The species that have the greatest effect tend to be generalist feeders, have high reproductive rates, attain large population sizes, and often due to their behavior and or small size, are easily transported or are difficult to

WILLIAM C. PITT; DANIEL S. VICE; MIKE E. PITZLER

2005-01-01

288

POTENTIAL DEVELOPMENTAL EFFECTS OF ATRAZINE ON AMPHIBIANS  

EPA Science Inventory

Recent research has generated conflicting results on the effects of atrazine on gonadal developmental (e.g., male hermaphroditism) in amphibians and how these effects influence secondary sexual characteristics (e.g., laryngeal muscle mass). The SAP is being asked to consider the...

289

Diseases of amphibian eggs and embryos  

USGS Publications Warehouse

Amphibians generally are prolific egg producers. In tropical and semi-tropical regions, deposition of eggs may occur year-round or may coincide with rainy seasons, while in temperate regions, deposition of eggs usually occurs immediately after emergence from hibernation. Numbers of eggs produced by each species may vary from a few dozen to thousands. Accordingly, some eggs may be infertile and wastage of embryos is to be expected. Fertility, viability and decomposition of eggs and embryos must be considered before it is assumed that diseases are present. An important consideration in the evaluation of egg masses is the fact that some will contain infertile and non-viable eggs. These infertile and nonviable eggs will undergo decomposition and they may appear similar to eggs that are infected by a pathogen. Evaluation of egg masses and embryos for the presence of disease may require repeated observations in a given breeding season as well as continued monitoring of egg masses during their growth and development and over successive breeding seasons. Amphibian eggs rarely are subjected to a comprehensive health (diagnostic) examination; hence, there is scant literature on the diseases of this life stage. Indeed, the eggs of some North American amphibians have yet to be described. Much basic physiology and normal biomedical baseline data on amphibian eggs is lacking. For example, it is known that the aquatic eggs of some species of shrimp quickly are coated by a protective and commensal bacterium that effectively impedes invasion of the eggs by other environmental organisms and potential pathogens. In the absence of this bacterium, shrimp eggs are rapidly killed by other bacteria and fungi (Green, 2001). The possibility that amphibian eggs also have important symbiotic or commensal bacteria needs to be investigated. Furthermore, the quantity and types of chemicals in the normal gelatinous capsules of amphibian eggs have scarcely been examined. Abnormalities of the female oviduct, either due to infectious disease, nutritional status, hormonal imbalances, or sublethal intoxications, could affect the quality of secreted gelatinous capsules on eggs, thus rendering an egg mass susceptible to other stressors. Diseases of amphibian eggs and embryos presented in this chapter are Lucke frog herpesvirus Ranavirus (iridovirus) infection Bacteria Watermold infection (saprolegniasis) Algae Microsporidia

Green, D.E.; Converse, K.A.

2005-01-01

290

Precocious Metamorphosis in the Juvenile Hormone–Deficient Mutant of the Silkworm, Bombyx mori  

PubMed Central

Insect molting and metamorphosis are intricately governed by two hormones, ecdysteroids and juvenile hormones (JHs). JHs prevent precocious metamorphosis and allow the larva to undergo multiple rounds of molting until it attains the proper size for metamorphosis. In the silkworm, Bombyx mori, several “moltinism” mutations have been identified that exhibit variations in the number of larval molts; however, none of them have been characterized molecularly. Here we report the identification and characterization of the gene responsible for the dimolting (mod) mutant that undergoes precocious metamorphosis with fewer larval–larval molts. We show that the mod mutation results in complete loss of JHs in the larval hemolymph and that the mutant phenotype can be rescued by topical application of a JH analog. We performed positional cloning of mod and found a null mutation in the cytochrome P450 gene CYP15C1 in the mod allele. We also demonstrated that CYP15C1 is specifically expressed in the corpus allatum, an endocrine organ that synthesizes and secretes JHs. Furthermore, a biochemical experiment showed that CYP15C1 epoxidizes farnesoic acid to JH acid in a highly stereospecific manner. Precocious metamorphosis of mod larvae was rescued when the wild-type allele of CYP15C1 was expressed in transgenic mod larvae using the GAL4/UAS system. Our data therefore reveal that CYP15C1 is the gene responsible for the mod mutation and is essential for JH biosynthesis. Remarkably, precocious larval–pupal transition in mod larvae does not occur in the first or second instar, suggesting that authentic epoxidized JHs are not essential in very young larvae of B. mori. Our identification of a JH–deficient mutant in this model insect will lead to a greater understanding of the molecular basis of the hormonal control of development and metamorphosis. PMID:22412378

Daimon, Takaaki; Kozaki, Toshinori; Niwa, Ryusuke; Kobayashi, Isao; Furuta, Kenjiro; Namiki, Toshiki; Uchino, Keiro; Banno, Yutaka; Katsuma, Susumu; Tamura, Toshiki; Mita, Kazuei; Sezutsu, Hideki; Nakayama, Masayoshi; Itoyama, Kyo; Shimada, Toru; Shinoda, Tetsuro

2012-01-01

291

Somatic, germline and sex hierarchy regulated gene expression during Drosophila metamorphosis  

PubMed Central

Background Drosophila melanogaster undergoes a complete metamorphosis, during which time the larval male and female forms transition into sexually dimorphic, reproductive adult forms. To understand this complex morphogenetic process at a molecular-genetic level, whole genome microarray analyses were performed. Results The temporal gene expression patterns during metamorphosis were determined for all predicted genes, in both somatic and germline tissues of males and females separately. Temporal changes in transcript abundance for genes of known functions were found to correlate with known developmental processes that occur during metamorphosis. We find that large numbers of genes are sex-differentially expressed in both male and female germline tissues, and relatively few are sex-differentially expressed in somatic tissues. The majority of genes with somatic, sex-differential expression were found to be expressed in a stage-specific manner, suggesting that they mediate discrete developmental events. The Sex-lethal paralog, CG3056, displays somatic, male-biased expression at several time points in metamorphosis. Gene expression downstream of the somatic, sex determination genes transformer and doublesex (dsx) was examined in two-day old pupae, which allowed for the identification of genes regulated as a consequence of the sex determination hierarchy. These include the homeotic gene abdominal A, which is more highly expressed in females as compared to males, as a consequence of dsx. For most genes regulated downstream of dsx during pupal development, the mode of regulation is distinct from that observed for the well-studied direct targets of DSX, Yolk protein 1 and 2. Conclusion The data and analyses presented here provide a comprehensive assessment of gene expression during metamorphosis in each sex, in both somatic and germline tissues. Many of the genes that underlie critical developmental processes during metamorphosis, including sex-specific processes, have been identified. These results provide a framework for further functional studies on the regulation of sex-specific development. PMID:19216785

Lebo, Matthew S; Sanders, Laura E; Sun, Fengzhu; Arbeitman, Michelle N

2009-01-01

292

Functional modifications associated with gastrointestinal tract organogenesis during metamorphosis in Atlantic halibut (Hippoglossus hippoglossus)  

PubMed Central

Background Flatfish metamorphosis is a hormone regulated post-embryonic developmental event that transforms a symmetric larva into an asymmetric juvenile. In altricial-gastric teleost fish, differentiation of the stomach takes place after the onset of first feeding, and during metamorphosis dramatic molecular and morphological modifications of the gastrointestinal (GI-) tract occur. Here we present the functional ontogeny of the developing GI-tract from an integrative perspective in the pleuronectiforme Atlantic halibut, and test the hypothesis that the multiple functions of the teleost stomach develop synchronously during metamorphosis. Results Onset of gastric function was determined with several approaches (anatomical, biochemical, molecular and in vivo observations). In vivo pH analysis in the GI-tract lumen combined with quantitative PCR (qPCR) of ? and ? subunits of the gastric proton pump (H+/K+-ATPase) and pepsinogen A2 indicated that gastric proteolytic capacity is established during the climax of metamorphosis. Transcript abundance of ghrelin, a putative orexigenic signalling molecule produced in the developing stomach, correlated (p?metamorphosis, and was thus independent of this event. Mechanical breakdown of food and transportation of chyme through the GI-tract was observed in vivo and resulted from phasic and propagating contractions established well before metamorphosis. The number of contractions in the midgut decreased at metamorphic climax synchronously with establishment of the stomach’s proteolytic capacity and its increased peristaltic activity. Putative osmoregulatory competence of the GI-tract, inferred by abundance of Na+/K+-ATPase ? transcripts, was already established at the onset of exogenous feeding and was unmodified by metamorphosis. Conclusions The functional specialization of the GI-tract was not exclusive to metamorphosis, and its osmoregulatory capacity and reservoir function were established before first feeding. Nonetheless, acid production and the proteolytic capacity of the stomach coincided with metamorphic climax, and also marked the onset of the stomach’s involvement in appetite regulation via ghrelin. PMID:24552353

2014-01-01

293

Establishing causality in the decline and deformity of amphibians: The amphibian research and monitoring initiative model  

USGS Publications Warehouse

Research to date has indicated that a range of environmental variables such as disease, parasitism, predation, competition, environmental contamination, solar ultraviolet radiation, climate change, or habitat alteration may be responsible for declining amphibian populations and the appearance of deformed organisms, yet in many cases no definitive environmental variable stands out as a causal factor. Multiple Stressors are often present in the habitat, and interactions among these can magnify injury to biota. This raises the possibility that the additive or synergistic impact of these Stressors may be the underlying cause of amphibian declines. Effective management for the restoration of amphibian populations requires the identification of causal factors contributing to their declines. A systematic approach to determine causality is especially important because initial impressions may be misleading or ambiguous. In addition, the evaluation of amphibian populations requires consideration of a broader spatial scale than commonly used in regulatory monitoring. We describe a systematic three-tiered approach to determine causality in amphibian declines and deformities. Tier 1 includes an evaluation of historic databases and extant data and would involve a desktop synopsis of the status of various stressors as well as site visits. Tier 2 studies are iterative, hypothesis driven studies beginning with general tests and continuing with analyses of increasing complexity as certain stressors are identified for further investigation. Tier 3 applies information developed in Tier 2 as predictive indicators of habitats and species at risk over broad landscape scales and provides decision support for the adaptive management of amphibian recovery. This comprehensive, tiered program could provide a mechanistic approach to identifying and addressing specific stressors responsible for amphibian declines across various landscapes.

Little, E.E.; Bridges, C.M.; Linder, G.; Boone, M.

2003-01-01

294

19 CFR 12.26 - Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans; prohibited...  

Code of Federal Regulations, 2014 CFR

...Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans...Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans...including mollusks and crustacea), amphibians, reptiles, or...

2014-04-01

295

19 CFR 12.26 - Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans; prohibited...  

Code of Federal Regulations, 2012 CFR

...Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans...Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans...including mollusks and crustacea), amphibians, reptiles, or...

2012-04-01

296

19 CFR 12.26 - Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans; prohibited...  

Code of Federal Regulations, 2010 CFR

...Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans...Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans...including mollusks and crustacea), amphibians, reptiles, or...

2010-04-01

297

76 FR 45603 - Agency Information Collection Activities: Comment Request for the North American Amphibian...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Comment Request for the North American Amphibian Monitoring Program (NAAMP) AGENCY...request (ICR) for the North American Amphibian Monitoring Program (NAAMP). As required...routes that are part of the North American Amphibian Monitoring Program. Volunteers use...

2011-07-29

298

The U.S. Geological Survey Amphibian Research and Monitoring Initiative--2011 Annual Update  

E-print Network

The U.S. Geological Survey Amphibian Research and Monitoring Initiative--2011 Annual Update Objective The Amphibian Research and Monitoring Initiative (ARMI) assists Department of the Interior (DOI) resource management agencies with information needs related to amphibian conservation. This includes

Torgersen, Christian

299

19 CFR 12.26 - Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans; prohibited...  

Code of Federal Regulations, 2013 CFR

...Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans...Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans...including mollusks and crustacea), amphibians, reptiles, or...

2013-04-01

300

19 CFR 12.26 - Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans; prohibited...  

Code of Federal Regulations, 2011 CFR

...Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans...Importations of wild animals, fish, amphibians, reptiles, mollusks, and crustaceans...including mollusks and crustacea), amphibians, reptiles, or...

2011-04-01

301

Linking global climate and temperature variability to widespread amphibian declines putatively caused  

E-print Network

Linking global climate and temperature variability to widespread amphibian declines putatively that the proposed link be- tween climate change and widespread amphibian declines, puta- tively caused widespread amphibian losses in genus Atelopus via increased regional temperature variability, which can

Rohr, Jason

302

Host Identity Matters in the Amphibian-Batrachochytrium dendrobatidis System: Fine-Scale  

E-print Network

Host Identity Matters in the Amphibian- Batrachochytrium dendrobatidis System: Fine-Scale Patterns pathogen, Batrachochytrium dendrobatidis, which is associated with worldwide amphibian population declines, Gondhalekar C, Olson DH, Blaustein AR (2013) Host Identity Matters in the Amphibian-Batrachochytrium

Blaustein, Andrew R.

303

Interactions between Batrachochytrium dendrobatidis and its amphibian hosts: a review of pathogenesis and immunity  

E-print Network

Review Interactions between Batrachochytrium dendrobatidis and its amphibian hosts: a review The fungus Batrachochytrium dendrobatidis (Bd ) causes a lethal skin disease of amphibians, chytridiomycosis. All rights reserved. Keywords: Amphibian declines; Batrachochytrium dendrobatidis; Chytridiomycosis

Rosenblum, Erica Bree

304

Direct and indirect effects of climate change on amphibian populations  

USGS Publications Warehouse

As part of an overall decline in biodiversity, populations of many organisms are declining and species are being lost at unprecedented rates around the world. This includes many populations and species of amphibians. Although numerous factors are affecting amphibian populations, we show potential direct and indirect effects of climate change on amphibians at the individual, population and community level. Shifts in amphibian ranges are predicted. Changes in climate may affect survival, growth, reproduction and dispersal capabilities. Moreover, climate change can alter amphibian habitats including vegetation, soil, and hydrology. Climate change can influence food availability, predator-prey relationships and competitive interactions which can alter community structure. Climate change can also alter pathogen-host dynamics and greatly influence how diseases are manifested. Changes in climate can interact with other stressors such as UV-B radiation and contaminants. The interactions among all these factors are complex and are probably driving some amphibian population declines and extinctions.

Blaustein, Andrew R.; Walls, Susan C.; Bancroft, Betsy A.; Lawler, Joshua J.; Searle, Catherine L.; Gervasi, Stephanie S.

2010-01-01

305

Helping Your Local Amphibians (HYLA): An Internet-Based Amphibian Course for Educators  

NASA Astrophysics Data System (ADS)

A pilot on-line course on amphibians was offered free to 20 educators around the United States in 1999. This course, called Helping Your Local Amphibians (HYLA), was the first of its kind on-line course for educators dealing with amphibian issues. It also used these animals as a focus to teach about the environment. The course lasted 9 weeks with some additional time for continued discussions and used various aspects of Internet technology (including a virtual conference center), media, and traditional paper-based products to complete the learning process. Five teachers were selected to attend a national amphibian summit hosted by the Center for Global Environmental Education, Hamline University, St. Paul, MN. The course was aimed primarily at upper elementary and middle school teachers, but participants included formal and nonformal educators. For the most part, educators expressed satisfaction with the course and the content, as well as the structure of the web site. For 80% of the group, this was their first Internet-based course. In addition, as part of the course, the educators were expected to take some action with their primary audiences to help local amphibian populations. This mainly took the form of surveys or habitat clean-ups. The development of the course was underwritten by grants from the National Fish and Wildlife Foundation, U.S. Fish and Wildlife Service, the Best Buy Children's Foundation, and Hamline University.

Murphy, Tony P.

2001-12-01

306

Wetland Management for Amphibians in the Willamette Valley  

USGS Publications Warehouse

Introduction In the past two decades, scientists around the world have increasingly noted losses of amphibian populations. Many of these declines have occurred in protected areas like national parks, where the causes mostly remain mysterious. However, in multipleuse landscapes, resource managers frequently face more obvious conservation problems and must make decisions that will affect amphibians. The purpose of this fact sheet is to present recent findings pertinent to wetland management and amphibians in a multiple-use landscape.

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

2004-01-01

307

Ranavirus outbreaks in amphibian populations of northern Idaho  

USGS Publications Warehouse

Ranavirus outbreaks, caused by pathogens in the genus Ranavirus (Family Iridoviridae), were the largest single cause of reported amphibian mass mortality events in the United States from 1996–2001 (Green et al. 2002). Mortality events associated with ranaviruses have been documented on five continents and throughout the latitudes and elevations where amphibians occur (Gray et al. 2009). However, the threat of ranaviruses to amphibian and reptile populations in specific regions is still largely unknown (Chinchar 2002; Gray et al. 2009).

Russell, Danelle M.; Goldberg, Caren S.; Sprague, Laura; Waits, Lisette P.; Green, D. Earl; Schuler, Krysten L.; Rosenblum, Erica Bree

2011-01-01

308

Perspective The Challenge of Conserving Amphibian Megadiversity in Madagascar  

E-print Network

Frogs from Madagascar constitute one of the richest groups of amphibian fauna in the world, with currently 238 described species; caecilians and salamanders are absent [1]. Several frog radiations of the island are species-rich and parallel lemurs and tenrecs in their astonishing morphological and ecological diversity. According to the Global Amphibian Assessment (GAA), Madagascar ranks as the country with the 12th highest amphibian species richness [2,3] (see also

Franco Andreone; Angus I. Carpenter; Neil Cox; Louis Du Preez; Karen Freeman; Samuel Furrer; Gerardo Garcia; Frank Glaw; Julian Glos; David Knox; Jörn Köhler; Joseph R. Mendelson; Vincenzo Mercurio; Russell A. Mittermeier; Robin D. Moore; Nirhy H. C. Rabibisoa; Herilala R; Harison R; Noromalala Rasoamampionona Raminosoa; Olga Ravoahangimalala Ramilijaona; Christopher J. Raxworthy; Denis Vallan; Miguel Vences; David R. Vieites; Ché Weldon

309

North American Amphibian Monitoring Program (NAAMP)  

NSDL National Science Digital Library

The US Geological Survey's Patuxent Wildlife Research Center hosts this nice page on the North American Amphibian Monitoring Program. At the site, users will find an overview and history of the program, as well as regional program updates, educational information, and links to related sites. The heart of the site is the Monitoring Programs section, however, as it provides in-depth content on the surveys, including Calling Surveys, Terrestrial Salamander Monitoring, Aquatic Surveys, Atlassing, and Western Surveys. This easy-to-navigate site has much to offer, whether for volunteers interested in participating in surveys, researchers searching for in-depth sampling methodology, or anyone interested in learning more about the distribution and abundance of amphibians in North America.

310

Neurosteroid Biosynthesis in the Brain of Amphibians  

PubMed Central

Amphibians have been widely used to investigate the synthesis of biologically active steroids in the brain and the regulation of neurosteroid production by neurotransmitters and neuropeptides. The aim of the present review is to summarize the current knowledge regarding the neuroanatomical distribution and biochemical activity of steroidogenic enzymes in the brain of anurans and urodeles. The data accumulated over the past two decades demonstrate that discrete populations of neurons and/or glial cells in the frog and newt brains express the major steroidogenic enzymes and are able to synthesize de novo a number of neurosteroids from cholesterol/pregnenolone. Since neurosteroidogenesis has been conserved during evolution from amphibians to mammals, it appears that neurosteroids must play important physiological functions in the central nervous system of vertebrates. PMID:22649387

Vaudry, Hubert; Do Rego, Jean-Luc; Burel, Delphine; Luu-The, Van; Pelletier, Georges; Vaudry, David; Tsutsui, Kazuyoshi

2011-01-01

311

Short-term fluctuation in salinity promotes rapid larval development and metamorphosis in Dendraster excentricus  

E-print Network

Short-term fluctuation in salinity promotes rapid larval development and metamorphosis; accepted 10 May 2007 Abstract The effect of constant and fluctuating salinity on larval development at different stages of development were kept either at 32 (controls), exposed to constant low salinity (22

George, Sophie B.

312

Stable isotope enrichment in laboratory ant colonies: effects of colony age, metamorphosis, diet, and fat storage  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ecologists use stable isotopes to infer diets and trophic levels of animals in food webs, yet some assumptions underlying these inferences have not been thoroughly tested. We used laboratory-reared colonies of Solenopsis invicta Buren (Formicidae: Solenopsidini) to test the effects of metamorphosis,...

313

Differentiation of the segmented tubular nephron and excretory duct during lamprey metamorphosis  

Microsoft Academic Search

The tubular portion of the adult lamprey nephron differentiates into various morphologically distinct segments during the seven stages of metamorphosis.At stage 1, a rudimentary nephron unit (RNU) originates from a nephrogenic mass attached to the peritoneum and elongates to become associated at its distal end with the archinephric (excretory) duct. The rapidly dividing cells show little sign of differentiation. Separation

John H. Youson

1984-01-01

314

EVIDENCE FOR ACCELERATED METAMORPHOSIS IN BULLFROG (RANA CATESBIEANA) TADPOLES IN AN EPHEMERAL POND  

EPA Science Inventory

It has been widely accepted that time to metamorphosis for non-native bullfrog tadpoles in the Pacific Northwest is greater than one year. We surveyed 22 ponds within the EE Wilson Reserve (Benton County, Oregon) for bullfrog tadpoles and metamorphs from April through September, ...

315

Development and metamorphosis of the planktotrophic larvae of Rostanga pulchra (Mollusca: Nudibranchia)  

Microsoft Academic Search

Rostanga pulchra MacFarland, a small (1 to 2 cm) dorid nudibranch, lays an average of 7000 eggs in the laboratory during a period of 30 days in the summer. The veligers hatch 15 to 16 days after oviposition and it takes another 35 to 40 days to become competent for metamorphosis at a temperature of 10° to 15°C. Larval cultures

F. S. Chia; R. Koss

1978-01-01

316

Sources of Energy for Increased Metabolic Demand During Metamorphosis of the Abalone Haliotis rufescens (Mollusca)  

Microsoft Academic Search

Pelagic, lecithotrophic (nonfeeding) larvae of the red abalone (Haliotis rzdfescens) settle and subse- quently metamorphose into benthic juveniles capable of feeding on particulate food. Thus, metamorphosis must be fueled by either endogenous reserves or a nonparticu- late food source such as dissolved organic material (DOM) in seawater. The metabolic rates (measured as oxygen consumption) of abalone larvae were found to

FRASER M. SHILLING; OVE HOEGH-GULDBERG; DONAL T. MANAHAN

317

The Steroid Hormone 20-Hydroxyecdysone Enhances Neurite Growth of Drosophila Mushroom Body Neurons Isolated during Metamorphosis  

Microsoft Academic Search

Mushroom bodies (MBs) are symmetrically paired neuropils in the insect brain that are of critical importance for associative olfactory learning and memory. In Drosophila melanogaster, the MB intrinsic neurons (Kenyon cells) undergo extensive reorga- nization at the onset of metamorphosis. A phase of rapid axonal degeneration without cell death is followed by axonal regener- ation. This re-elaboration occurs as levels

Robert Kraft; Richard B. Levine; Linda L. Restifo

318

Regulation of pituitary thyrotropin gene expression during Xenopus metamorphosis: negative feedback is functional throughout  

E-print Network

. It is well established that the hypothalamus and pituitary gland regulate tadpole thyroid activityRegulation of pituitary thyrotropin gene expression during Xenopus metamorphosis: negative feedback to explain the increase and sustained expression of pituitary thyro- tropin (TSH) in the presence of elevated

Denver, Robert J.

319

Control of Pituitary Thyroid-stimulating Hormone Synthesis and Secretion by Thyroid Hormones during Xenopus Metamorphosis  

EPA Science Inventory

Serum thyroid hormone (TH) concentrations in anuran larvae rise rapidly during metamorphosis. Such a rise in an adult anuran would inevitably trigger a negative feedback response resulting in decreased synthesis and secretion of thyroid-stimulating hormone (TSH) by the pituitary....

320

Metamorphosis of a Butterfly-Associated Bacterial Tobin J. Hammer1,2  

E-print Network

Metamorphosis of a Butterfly-Associated Bacterial Community Tobin J. Hammer1,2 *, W. Owen McMillan2 Smithsonian Tropical Research Institute, Panama City, Republic of Panama Abstract Butterflies are charismatic these microbial symbionts are little-studied, despite their likely importance to butterfly ecology and evolution

Colorado at Boulder, University of

321

Emerging infectious diseases and amphibian population declines.  

PubMed Central

We review recent research on the pathology, ecology, and biogeography of two emerging infectious wildlife diseases, chytridiomycosis and ranaviral disease, in the context of host-parasite population biology. We examine the role of these diseases in the global decline of amphibian populations and propose hypotheses for the origins and impact of these panzootics. Finally, we discuss emerging infectious diseases as a global threat to wildlife populations. PMID:10603206

Daszak, P.; Berger, L.; Cunningham, A. A.; Hyatt, A. D.; Green, D. E.; Speare, R.

1999-01-01

322

New Mexico Species List : Reptiles and Amphibians  

NSDL National Science Digital Library

The New Mexico Department of Game and Fish compiled this extensive list of reptiles and amphibians for New Mexico and Arizona. Organized alphabetically by common name (with scientific name in parenthesis), each hyperlinked name connects the viewer to further details (taxonomy, status, life history, distribution, habitat information, food habits, environmental associations, management practices, and references) via the Biota Information System Of New Mexico (BISON). Researchers will appreciate the extent and clarity of information in this database.

323

Bent's Old Fort: Amphibians and Reptiles  

USGS Publications Warehouse

Bent's Old Fort National Historic Site sits along the Arkansas River in the semi-desert prairie of southeastern Colorado. The USGS provided assistance in designing surveys to assess the variety of herpetofauna (amphibians and reptiles) resident at this site. This brochure is the results of those efforts and provides visitors with information on what frogs, toads, snakes and salamanders might be seen and heard at Bent's Old Fort.

Muths, E.

2008-01-01

324

Analgesia in Amphibians: Preclinical Studies and Clinical Applications  

PubMed Central

SYNOPSIS Preclinical studies of analgesia in amphibians or recommendations for clinical use of analgesics in amphibian species are extremely limited. This article briefly reviews the issues surrounding the use of analgesics in amphibians starting with common definitions of pain and analgesia when applied to non-human animals. Nociceptive and endogenous opioid systems in amphibians are reviewed and results of preclinical research on opioid and non-opioid analgesics summarized. Recommended opioid and non-opioid analgesics are summarized and practical recommendations made for their clinical use. PMID:21074701

Stevens, Craig W.

2010-01-01

325

Amphibian Decline: An Integrated Analysis of Multiple Stressor Effects  

USGS Publications Warehouse

Although the effects of contaminants on amphibians have been studied for decades, relatively little is known about these effects compared to the more intensively studied mammals. and birds. Science has advanced its understanding of the complexities linked to declining amphibian populations; however, there are many remaining questions whose answers would directly benefit amphibians and adaptive management plans ministering to them. In an effort to answer those questions and focus on ecological risk assessment of amphibians, scientists, researchers, and resource management professionals from diverse fields participated in a Society of Environmental Toxicology and Chemistry (SETAC)-Johnson Foundation Wingspread conference with three goals: characterize a process that would bring a range of interdisciplinary technical and management tools to the tasks of causal analysis; demonstrate the current state of available technical tools to assess amphibian populations exposed to various environmental stressors; and focus on identifying research that would likely benefit sustainable populations through adaptive management programs. A result of the Wingspread conference, Amphibian Decline examines the ecotoxicology and stressors of amphibians in an attempt to address issues related to declining amphibian populations and the role that various stressors might have in those losses. It identifies gaps in current data, interprets information into an existing framework, and points toward critical areas for future research. Through the combined efforts of research and resource management communities, recommendations can be developed to change current policies and management actions to address the problem of amphibian decline.

2003-01-01

326

ORIGINAL PAPER Ancient behaviors of larval amphibians in response  

E-print Network

, Batrachochytrium dendrobatidis Barbara A. Han & Paul W. Bradley & Andrew R. Blaustein Received: 19 September 2007 examined how a globally emerging amphibian pathogen, Batrachochytrium dendrobatidis (BD), affected two key

Han, Barbara A.

327

Preliminary characterization of calcium binding to melano-somes isolated from amphibian oocytes  

E-print Network

Preliminary characterization of calcium binding to melano- somes isolated from amphibian oocytes. The steroid hormone, progesterone, induces meiotic maturatilon of the full- grown amphibian oocyte (Smith

Paris-Sud XI, Université de

328

Interacting Symbionts and Immunity in the Amphibian Skin Mucosome Predict Disease Risk and Probiotic Effectiveness  

PubMed Central

Pathogenesis is strongly dependent on microbial context, but development of probiotic therapies has neglected the impact of ecological interactions. Dynamics among microbial communities, host immune responses, and environmental conditions may alter the effect of probiotics in human and veterinary medicine, agriculture and aquaculture, and the proposed treatment of emerging wildlife and zoonotic diseases such as those occurring on amphibians or vectored by mosquitoes. Here we use a holistic measure of amphibian mucosal defenses to test the effects of probiotic treatments and to assess disease risk under different ecological contexts. We developed a non-invasive assay for antifungal function of the skin mucosal ecosystem (mucosome function) integrating host immune factors and the microbial community as an alternative to pathogen exposure experiments. From approximately 8500 amphibians sampled across Europe, we compared field infection prevalence with mucosome function against the emerging fungal pathogen Batrachochytrium dendrobatidis. Four species were tested with laboratory exposure experiments, and a highly susceptible species, Alytes obstetricans, was treated with a variety of temperature and microbial conditions to test the effects of probiotic therapies and environmental conditions on mucosome function. We found that antifungal function of the amphibian skin mucosome predicts the prevalence of infection with the fungal pathogen in natural populations, and is linked to survival in laboratory exposure experiments. When altered by probiotic therapy, the mucosome increased antifungal capacity, while previous exposure to the pathogen was suppressive. In culture, antifungal properties of probiotics depended strongly on immunological and environmental context including temperature, competition, and pathogen presence. Functional changes in microbiota with shifts in temperature provide an alternative mechanistic explanation for patterns of disease susceptibility related to climate beyond direct impact on host or pathogen. This nonlethal management tool can be used to optimize and quickly assess the relative benefits of probiotic therapies under different climatic, microbial, or host conditions. PMID:24789229

Woodhams, Douglas C.; Brandt, Hannelore; Baumgartner, Simone; Kielgast, Jos; Küpfer, Eliane; Tobler, Ursina; Davis, Leyla R.; Schmidt, Benedikt R.; Bel, Christian; Hodel, Sandro; Knight, Rob; McKenzie, Valerie

2014-01-01

329

Interacting symbionts and immunity in the amphibian skin mucosome predict disease risk and probiotic effectiveness.  

PubMed

Pathogenesis is strongly dependent on microbial context, but development of probiotic therapies has neglected the impact of ecological interactions. Dynamics among microbial communities, host immune responses, and environmental conditions may alter the effect of probiotics in human and veterinary medicine, agriculture and aquaculture, and the proposed treatment of emerging wildlife and zoonotic diseases such as those occurring on amphibians or vectored by mosquitoes. Here we use a holistic measure of amphibian mucosal defenses to test the effects of probiotic treatments and to assess disease risk under different ecological contexts. We developed a non-invasive assay for antifungal function of the skin mucosal ecosystem (mucosome function) integrating host immune factors and the microbial community as an alternative to pathogen exposure experiments. From approximately 8500 amphibians sampled across Europe, we compared field infection prevalence with mucosome function against the emerging fungal pathogen Batrachochytrium dendrobatidis. Four species were tested with laboratory exposure experiments, and a highly susceptible species, Alytes obstetricans, was treated with a variety of temperature and microbial conditions to test the effects of probiotic therapies and environmental conditions on mucosome function. We found that antifungal function of the amphibian skin mucosome predicts the prevalence of infection with the fungal pathogen in natural populations, and is linked to survival in laboratory exposure experiments. When altered by probiotic therapy, the mucosome increased antifungal capacity, while previous exposure to the pathogen was suppressive. In culture, antifungal properties of probiotics depended strongly on immunological and environmental context including temperature, competition, and pathogen presence. Functional changes in microbiota with shifts in temperature provide an alternative mechanistic explanation for patterns of disease susceptibility related to climate beyond direct impact on host or pathogen. This nonlethal management tool can be used to optimize and quickly assess the relative benefits of probiotic therapies under different climatic, microbial, or host conditions. PMID:24789229

Woodhams, Douglas C; Brandt, Hannelore; Baumgartner, Simone; Kielgast, Jos; Küpfer, Eliane; Tobler, Ursina; Davis, Leyla R; Schmidt, Benedikt R; Bel, Christian; Hodel, Sandro; Knight, Rob; McKenzie, Valerie

2014-01-01

330

Conceptual Design for the Amphibian Research and Monitoring Initiative (ARMI)  

NASA Astrophysics Data System (ADS)

In 2000, the President of the United States (US) and Congress directed Department of Interior (DOI) agencies to develop a program for monitoring trends in amphibian populations on DOI lands and to conduct research into causes of declines. The U.S. Geological Survey (USGS) was given lead responsibility for planning and implementing the Amphibian Research and Monitoring Initiative (ARMI) in cooperation with the National Park Service (NPS), Fish and Wildlife Service, and Bureau of Land Management. The program objectives are to (1) establish a network for monitoring the status and distribution of amphibian species on DOI lands; (2) identify and monitor environmental conditions known to affect amphibian populations; (3) conduct research on causes of amphibian population change and malformations; and (4) provide information to resource managers, policy makers, and the public in support of amphibian conservation. The ARMI program will integrate research efforts of USGS, other Federal, and non-federal herpetologists, hydrologists, and geographers across the Nation. ARMI will conduct a small number (~20) of intensive research efforts (for example, studies linking amphibian population changes to hydrologic conditions) and a larger number (~50) of more generalized inventory and monitoring studies encompassing broader areas such as NPS units. ARMI will coordinate with and try to augment other amphibian inventory studies such as the National Amphibian Atlas and the North American Amphibian Monitoring Program. ARMI will develop and test protocols for the standardized collection of amphibian data and provide a centrally managed database designed to simplify data entry, retrieval, and analysis. ARMI pilot projects are underway at locations across the US.

Battaglin, W. A.; Langtimm, C. A.; Adams, M. J.; Gallant, A. L.; James, D. L.

2001-12-01

331

The influence of temperature and light on larval pre-settlement metamorphosis: a study of the effects of environmental factors on pre-settlement metamorphosis of the solitary ascidian Styela canopus  

Microsoft Academic Search

This study investigated the effects of two environmental factors, temperature and light, on larval settlement and metamorphosis in the solitary ascidian Styela canopus. The results revealed that larval settlement rates decreased with increasing temperature in the range 12–30°C. We also demonstrated for the first time that pre-settlement metamorphosis of ascidian larvae can occur as a function of temperature. We suggest

Danqing Feng; Caihuan Ke; Changyi Lu; Shaojing Li

2010-01-01

332

Topoisomerase Assays  

PubMed Central

Topoisomerases are nuclear enzymes that play essential roles in DNA replication, transcription, chromosome segregation, and recombination. All cells have two major forms of topoisomerases: type I, which makes single-stranded cuts in DNA, and type II enzymes, which cut and pass double-stranded DNA. DNA topoisomerases are important targets of approved and experimental anti-cancer agents. The protocols described in this unit are of assays used to assess new chemical entities for their ability to inhibit both forms of DNA topoisomerase. Included are an in vitro assay for topoisomerase I activity based on relaxation of supercoiled DNA and an assay for topoisomerase II based on the decatenation of double-stranded DNA. The preparation of mammalian cell extracts for assaying topoisomerase activity is described, along with a protocol for an ICE assay for examining topoisomerase covalent complexes in vivo and an assay for measuring DNA cleavage in vitro. PMID:22684721

Nitiss, John L.; Soans, Eroica; Rogojina, Anna; Seth, Aman; Mishina, Margarita

2012-01-01

333

Opsonophagocytic assay.  

PubMed

The opsonophagocytic killing (OPK) assay is used as a correlate for protection to measure the functional capacities of vaccine-candidate-raised antibodies. This in vitro assay aids selecting promising vaccines by demonstrating whether the vaccine-induced antibodies drive efficient complement deposition and subsequent opsonophagocytic killing. Here, we describe two protocols for an OPK assay using either human-derived PMNs or cultured HL-60 cells. PMID:24218277

Dwyer, Markryan; Gadjeva, Mihaela

2014-01-01

334

IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS, VOL. 2, NO. 4, DECEMBER 1996 337 Image Metamorphosis with  

E-print Network

. The resulting technique, based on B-spline approximation, is simpler and faster than previous warp generation B-spline interpolation. -------------------- 3 -------------------- 1 INTRODUCTION MAGE blending. Implementation details are furnished and comparisons among various metamorphosis techniques

Wolberg, George

335

Great Lakes wetlands as amphibian habitats: A review  

Microsoft Academic Search

Amphibians are highly adapted for life in wetland habitats. They form a major component of wetland faunas, and being both prey and predator, they are important in ecosystem functioning. Wetlands provide aquatic habitats that amphibians require for breeding, development, foraging, hibernation and refuge, and they form an interface with essential adjacent upland habitat. The size and type of wetlands as

S. J. Hecnar

2004-01-01

336

Sahonagasy Action Plan Conservation Programs for the Amphibians of Madagascar  

E-print Network

Sahonagasy Action Plan Conservation Programs for the Amphibians of Madagascar Programmes de Conservation pour les Amphibiens de Madagascar Edited by / Edité par Franco Andreone Herilala Randriamahazo ACSAM A Conservation Strategy for the Amphibians of Madagascar Une Stratégie de Conservation pour les

Andreone, Franco

337

MOJAVE DESERT SPRING: THE AMPHIBIAN POINT OF VIEW  

EPA Science Inventory

Numerous springs are scattered throughout the eastern Mojave Desert, most of which are concentrated near the bases of mountain ranges. Spring-fed wetlands in this region comprise nearly all the available habitat for amphibians. We surveyed 128 springs for amphibians and habitat t...

338

Evaluating the Links Between Climate, Disease Spread, and Amphibian Declines  

Microsoft Academic Search

Human alteration of the environment has arguably propelled the Earth into its sixth mass extinction event and amphibians, the most threatened of all vertebrate taxa, are at the forefront. Many of the worldwide amphibian declines have been caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd), and two contrasting hypotheses have been proposed to explain these declines. Positive correlations between global

Jason R. Rohr; Thomas R. Raffel; John M. Romansic; Hamish McCallum; Peter J. Hudson

2008-01-01

339

Evaluating the links between climate, disease spread, and amphibian declines  

Microsoft Academic Search

Human alteration of the environment has arguably propelled the Earth into its sixth mass extinction event and amphibians, the most threatened of all vertebrate taxa, are at the forefront. Many of the worldwide amphibian declines have been caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd), and two contrasting hypotheses have been proposed to explain these declines. Positive correlations between global

Jason R. Rohr; Thomas R. Raffel; John M. Romansic; Hamish McCallum; Peter J. Hudson

2008-01-01

340

The effect of road kills on amphibian populations  

Microsoft Academic Search

The diurnal movement patterns of Triturus vulgaris, Triturus cristatus, Pelobates fuscus, Bufo bufo, Rana temporaria, and Rana arvalis were investigated during five breeding seasons (1994–1998). Two main questions were addressed: (1) What is the probability of an individual amphibian getting killed when crossing the road? and (2) What fraction of the amphibian populations gets killed by traffic? The rate of

Tove Hels; Erik Buchwald

2001-01-01

341

Incorporating Amphibian Malformations into Inquiry-Based Learning  

ERIC Educational Resources Information Center

Amphibians, a class of vertebrates consisting of frogs and toads, salamanders, and caecilians, are excellent organisms for middle school science students to study because of their ecological significance. Because they exchange oxygen and carbon dioxide through their skin, amphibians absorb any chemicals or substances present in their immediate…

Talley, Brooke L.

2007-01-01

342

AMPHIBIAN DECLINES AND ENVIRONMENTAL CHANGE IN THE EASTERN "MOJAVE DESERT"  

EPA Science Inventory

A number of amphibian species historically inhabited sparsely distributed wetlands in the Mojave Desert, USA, habitats that have been dramatically altered or eliminated as a result of human activities. The population status and distribution of amphibians were investigated in a 20...

343

Amphibian Oasis: Designing and Building a Schoolyard Pond.  

ERIC Educational Resources Information Center

Building a pond in a schoolyard is a rewarding way to help boost local populations of amphibians, to increase the natural value of school grounds, and to serve as a locale for observing the life cycles of plants, invertebrates, and amphibians. This article outlines important considerations in designing and building a pond from siting through…

Gosselin, Heather; Johnson, Bob

1996-01-01

344

Amphibians and Reptiles from Paramakatoi and Kato, Guyana  

USGS Publications Warehouse

We report the herpetofauna of two neighboring upland locations in west-central Guyana. Twenty amphibian and 24 reptile species were collected. Only 40% of amphibians and 12.5% of reptiles were collected in both locations. This is one of the few collections made at upland (750–800 m) locations in the Guiana Shield.

MacCulloch, Ross D.; Reynolds, Robert P.

2012-01-01

345

Population Declines and Priorities for Amphibian Conservation in Latin America  

Microsoft Academic Search

Although dramatic amphibian population declines have been reported worldwide, our under- standing of the extent of the declines in Latin America, where amphibian diversity is high, is limited to a few well-documented studies. To better understand the geographic extent of declines, their possible causes, and the measures needed to improve Latin American scientists' ability to research the phenomenon and make

Bruce E. Young; Karen R. Lips; Jamie K. Reaser; Roberto Ibanez; Antonio W. Salas; J. Rogelio Cedeno; Luis A. Coloma; Santiago Ron; Enrique La Marca; John R. Meyer; Antonio Munoz; Federico Bolanos; Gerardo Chaves; David Romo

2001-01-01

346

All about Amphibians. Animal Life for Children. [Videotape].  

ERIC Educational Resources Information Center

This videotape teaches children about their favorite amphibious creatures, as well as amphibians' nearest cousins--toads, newts, and salamanders. Young students discover how these amazing creatures can live both in and out of water, learn about the amphibious life cycle, and compare the differences between amphibians and reptiles. This videotape…

2000

347

Distribution of woodland amphibians along a forest fragmentation gradient  

Microsoft Academic Search

Understanding how changes in land-use affect the distribution and abundance of organisms is an increasingly important question in landscape ecology. Amphibians may be especially prone to local extinction resulting from human-caused transformation and fragmentation of their habitats owing to the spatially and temporally dynamic nature of their populations. In this study, distributions of five species of woodland amphibians with differing

James P. Gibbs

1998-01-01

348

Global amphibian declines: a perspective from the Caribbean  

Microsoft Academic Search

Recent concern over the possibility of a global decline in amphibians prompted this assessment of the West Indian species. At the species level, the West Indian amphibian fauna (156 species, all frogs and toads) has not undergone a general decline, and no species is known to be extinct. However, one Puerto Rican species (Eleutherodactylus karlschmidti) has not been seen in

S. Blair Hedges

1993-01-01

349

Forest mediated light regime linked to amphibian distribution and performance  

Microsoft Academic Search

The vegetation in and around the basins of ephemeral wetlands can greatly affect light environments for aquatic species such as amphibians. We used hemispherical photographs to quantify the light environment in terms of the global site factor (GSF), the proportion of available solar radiation that actually strikes the wetland. We compared GSF to the distribution and performance of two amphibian

M. A. Halverson; D. K. Skelly; J. M. Kiesecker; L. K. Freidenburg

2003-01-01

350

Herpetological Review 43(1), 2012 78 AMPHIBIAN DISEASES  

E-print Network

ChOls. 1999. Batrachochytrium dendrobatidis gen et sp. nov., a chytrid pathogen to amphibians. Mycologia 91 europäischer Amphibien durch den Haut- pilz Batrachochytrium dendrobatidis. ZfH 18:1­17. OuelleT, m., i of Amphibians and Reptiles Survey of Ranavirus and the Fungus Batrachochytrium dendrobatidis in Frogs of Central

Gray, Matthew

351

Species Review of Amphibian Extinction Risks in Madagascar: Conclusions from the Global Amphibian Assessment  

Microsoft Academic Search

We assessed the extinction risks of Malagasy amphibians by evaluating their distribution, occur- rence in protected areas, population trends, habitat quality, and prevalence in commercial trade. We estimated and mapped the distribution of each of the 220 described Malagasy species and applied, for the first time, the IUCN Red List categories and criteria to all species described at the time

FRANCO ANDREONE; JOHN E. CADLE; NEIL COX; FRANK GLAW; RONALD A. NUSSBAUM; CHRISTOPHER J. RAXWORTHY; SIMON N. STUART; DENIS VALLAN; MIGUEL VENCES

2005-01-01

352

Partners in amphibian and reptile conservation 2013 annual report  

USGS Publications Warehouse

Partners in Amphibian and Reptile Conservation (PARC) was established in 1999 to address the widespread declines, extinctions, and range reductions of amphibians and reptiles, with a focus on conservation of taxa and habitats in North America. Amphibians and reptiles are affected by a broad range of human activities, both as incidental effects of habitat alteration and direct effect from overexploitation; these animals are also challenged by the perception that amphibians and reptiles are either dangerous or of little environmental or economic value. However, PARC members understand these taxa are important parts of our natural an cultural heritage and they serve important roles in ecosystems throughout the world. With many amphibians and reptiles classified as threatened with extinction, conservation of these animals has never been more important.

Conrad, Paulette M., (Edited By); Weir, Linda A.; Nanjappa, Priya

2014-01-01

353

Amphibian XIS: an immersion lithography microstepper platform  

NASA Astrophysics Data System (ADS)

Recent advances in immersion lithography have created the need for a small field microstepper to carry out the early learning necessary for next generation device application. Combined with fluid immersion, multiple-beam lithography can provide an opportunity to explore lithographic imaging at oblique propagation angles and extreme NA imaging. Using the phase preserving properties of Smith Talbot interferometry, the Amphibian XIS immersion lithography microstepper has been created for research and development applications directed toward sub-90nm patterning. The system has been designed for use at ArF and KrF excimer laser wavelengths, based on a fused silica or sapphire prism lens with numerical aperture values up to 1.60. Combined with a chromeless phase grating mask, two and four beam imaging is made possible for feature resolution to 35nm. The approach is combined with X-Y staging to provide immersion imaging on a microstepper platform for substrates ranging up to 300mm. The Amphibian system consists of single or dual wavelength sources (193nm and 248nm), a 2mm exposure field size, stage accuracy better than 1 um, polarization control over a full range from linear polarization to unpolarized illumination, full control of exposure dose and demodulation (to synthesize defocus), and the ability to image both line patterns as well as contact features. A fluid control system allows use of water or alternative fluids, with the ability to change fluids rapidly between wafers. The Amphibian system is fully enclosed in a HEPA and amine controlled environment for use in fab or research environments.

Smith, Bruce W.; Bourov, Anatoly; Fan, Yongfa; Cropanese, Frank; Hammond, Peter

2005-05-01

354

Amphibian otoconia in normal and altered gravity  

NASA Astrophysics Data System (ADS)

In vertebrates, the macular end organs of the inner ear are gravity sensing organs. They consist of a neuroepithelium overlaid by a mass of little otoconia or by a single large otolith. These crystallites provide essential informations for orientation and equilibrium. They are mosaic biominerals composed of proteic and inorganic phases. In amphibian adults, the mineral phase is calcium carbonate in the form of calcite or aragonite. The calcitic otoconia with a rhomboedric shape are observed in the utricle of Pleurodeles waltl (urodele amphibian). The aragonitic otoconia with a prismatic or a fusiform shape are observed in the saccule and lagena of Pleurodeles, and in the three gravity-sensing regions of Xenopus laevis (anuran amphibian). The aragonitic biocrystallites are in different proportions depending on the inner ear regions. During the development, in Pleurodeles larvae, we observed that saccular otoconia changed from calcitic to aragonitic form. In Xenopus tadpoles, we observed peculiar otoconia with a rhomboedric-like morphology or a tripartite morphology. We called the latter crystallites cauliflower-like otoconia according to the aspect. We reported our observations performed after two space missions, the experiment Torcol which flew on the French Soyuz taxi flight Perseus to MIR (launch: February 20, 1999; landing: August 28, 1999), and the experiment Aquarius-Xenopus which flew on the French Soyuz taxi flight Andromède to ISS (launch: October 21, 2001; landing: October 31, 2001). After a long journey in space, both calcitic and aragonitic otoconia were altered in Pleurodeles adults. After a short space mission, otoconia with rhomboedric, fusiform or cauliflower-like aspects were observed in Xenopus tadpoles. In these tadpoles, otoconia with rhomboedric aspect were never mixed with the other otoconia types, whereas fusiform otoconia were never alone. Cauliflower-shaped otoconia were alone or associated with fusiform otoconia. The study needs further investigations.

Membre, H.; Horn, E.; Dournon, C.

355

Autocrine regulation of ecdysone synthesis by ?3-octopamine receptor in the prothoracic gland is essential for Drosophila metamorphosis  

PubMed Central

In Drosophila, pulsed production of the steroid hormone ecdysone plays a pivotal role in developmental transitions such as metamorphosis. Ecdysone production is regulated in the prothoracic gland (PG) by prothoracicotropic hormone (PTTH) and insulin-like peptides (Ilps). Here, we show that monoaminergic autocrine regulation of ecdysone biosynthesis in the PG is essential for metamorphosis. PG-specific knockdown of a monoamine G protein-coupled receptor, ?3-octopamine receptor (Oct?3R), resulted in arrested metamorphosis due to lack of ecdysone. Knockdown of tyramine biosynthesis genes expressed in the PG caused similar defects in ecdysone production and metamorphosis. Moreover, PTTH and Ilps signaling were impaired by Oct?3R knockdown in the PG, and activation of these signaling pathways rescued the defect in metamorphosis. Thus, monoaminergic autocrine signaling in the PG regulates ecdysone biogenesis in a coordinated fashion on activation by PTTH and Ilps. We propose that monoaminergic autocrine signaling acts downstream of a body size checkpoint that allows metamorphosis to occur when nutrients are sufficiently abundant. PMID:25605909

Ohhara, Yuya; Shimada-Niwa, Yuko; Kayashima, Yasunari; Hayashi, Yoshiki; Akagi, Kazutaka; Ueda, Hitoshi; Yamakawa-Kobayashi, Kimiko; Kobayashi, Satoru

2015-01-01

356

Late Cretaceous Vicariance in Gondwanan Amphibians  

PubMed Central

Overseas dispersals are often invoked when Southern Hemisphere terrestrial and freshwater organism phylogenies do not fit the sequence or timing of Gondwana fragmentation. We used dispersal-vicariance analyses and molecular timetrees to show that two species-rich frog groups, Microhylidae and Natatanura, display congruent patterns of spatial and temporal diversification among Gondwanan plates in the Late Cretaceous, long after the presumed major tectonic break-up events. Because amphibians are notoriously salt-intolerant, these analogies are best explained by simultaneous vicariance, rather than by oceanic dispersal. Hence our results imply Late Cretaceous connections between most adjacent Gondwanan landmasses, an essential concept for biogeographic and palaeomap reconstructions. PMID:17183706

Bocxlaer, Ines Van; Roelants, Kim; Biju, S.D.; Nagaraju, J.; Bossuyt, Franky

2006-01-01

357

Ecology: global warming and amphibian losses.  

PubMed

Is global warming contributing to amphibian declines and extinctions by promoting outbreaks of the chytrid fungus Batrachochytrium dendrobatidis? Analysing patterns from the American tropics, Pounds et al. envisage a process in which a single warm year triggers die-offs in a particular area (for instance, 1987 in the case of Monteverde, Costa Rica). However, we show here that populations of two frog species in the Australian tropics experienced increasing developmental instability, which is evidence of stress, at least two years before they showed chytrid-related declines. Because the working model of Pounds et al. is incomplete, their test of the climate-linked epidemic hypothesis could be inconclusive. PMID:17538571

Alford, Ross A; Bradfield, Kay S; Richards, Stephen J

2007-05-31

358

Effect of road deicing salt on the susceptibility of amphibian embryos to infection by water molds  

Microsoft Academic Search

Some causative agents of amphibian declines act synergistically to impact individual amphibians and their populations. In particular, pathogenic water molds (aquatic oomycetes) interact with environmental stressors and increase mortality in amphibian embryos. We documented colonization of eggs of three amphibian species, the wood frog (Rana sylvatica), the green frog (Rana clamitans), and the spotted salamander (Ambystoma maculatum), by water molds

Nancy E. Karraker; Gregory R. Ruthig

2009-01-01

359

Global gene expression profiles for life stages of the deadly amphibian pathogen  

E-print Network

Global gene expression profiles for life stages of the deadly amphibian pathogen Batrachochytrium by the Editorial Board September 8, 2008 (received for review April 30, 2008) Amphibians around the world are being. amphibian population decline chytrid fungal pathogenicity genomics Amphibian populations around the world

Rosenblum, Erica Bree

360

Amphibian populations around the world are declining at alarming rates, but the causes of  

E-print Network

Amphibian populations around the world are declining at alarming rates, but the causes of most success in amphibians. Developmental pathways in embryonic amphibians can be altered when embryos exposure has formed the foundation for the only widely accepted standardized amphibian toxicity test (frog

Hopkins, William A.

361

Historical perspective: Hormonal regulation of behaviors in amphibians Frank L. Moorea,*, Sunny K. Boydb  

E-print Network

Historical perspective: Hormonal regulation of behaviors in amphibians Frank L. Moorea,*, Sunny K Abstract This review focuses on research into the hormonal control of behaviors in amphibians behaviors in adult amphibians, but causal relationships are not as well established in amphibians

Boyd, Sunny K.

362

Short Communication Amphibian-killing fungus loses genetic diversity as it spreads across the New World  

E-print Network

Short Communication Amphibian-killing fungus loses genetic diversity as it spreads across the New December 2011 Available online 29 December 2011 Keywords: Amphibian declines Batrachochytrium dendrobatidis to identify factors driving disease out- breaks. Amphibian chytridiomycosis is a recently emerged amphibian

Zamudio, Kelly R.

363

Amphibians at Greatest Risk Have Common Traits by Liz Osborn CurrentResults.com  

E-print Network

Amphibians at Greatest Risk Have Common Traits by Liz Osborn © CurrentResults.com The largest analysis ever undertaken of what makes the existence of amphibians most precarious finds a single and on the whole amphibians have not been doing well lately. Censuses recorded for over 4000 amphibian species from

Tipple, Brett

364

Human land use and patterns of parasitism in tropical amphibian hosts  

E-print Network

Human land use and patterns of parasitism in tropical amphibian hosts Valerie J. Mc: Amphibian Parasite Land use Tropics Forest Pasture A B S T R A C T Landscape alterations by humans can amphibians was associated with land use change, I studied three species of amphibians, Rana vaillanti

McKenzie, Valerie

365

2003 Blackwell Publishing Ltd. http://www.blackwellpublishing.com/journals/ddi 151 SPECIAL ISSUE: AMPHIBIAN DECLINES  

E-print Network

: AMPHIBIAN DECLINES Diversity and Distributions (2003) 9, 151­163 Blackwell Science, Ltd Amphibian declines 99164­4236, U.S.A. E-mail: astorfer@wsu.edu Abstract. The amphibian decline problem is complex amphibian populations. First, a statistically sensitive moni- toring approach is necessary to determine

Storfer, Andrew

366

Cool Temperatures Reduce Antifungal Activity of Symbiotic Bacteria of Threatened Amphibians – Implications for Disease Management and Patterns of Decline  

PubMed Central

Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a widespread disease of amphibians responsible for population declines and extinctions. Some bacteria from amphibians’ skins produce antimicrobial substances active against Bd. Supplementing populations of these cutaneous antifungal bacteria might help manage chytridiomycosis in wild amphibians. However, the activity of protective bacteria may depend upon environmental conditions. Biocontrol of Bd in nature thus requires knowledge of how environmental conditions affect their anti-Bd activity. For example, Bd-driven amphibian declines have often occurred at temperatures below Bd’s optimum range. It is possible these declines occurred due to reduced anti-Bd activity of bacterial symbionts at cool temperatures. Better understanding of the effects of temperature on chytridiomycosis development could also improve risk evaluation for amphibian populations yet to encounter Bd. We characterized, at a range of temperatures approximating natural seasonal variation, the anti-Bd activity of bacterial symbionts from the skins of three species of rainforest tree frogs (Litoria nannotis, Litoria rheocola, and Litoria serrata). All three species declined during chytridiomycosis outbreaks in the late 1980s and early 1990s and have subsequently recovered to differing extents. We collected anti-Bd bacterial symbionts from frogs and cultured the bacteria at constant temperatures from 8°C to 33°C. Using a spectrophotometric assay, we monitored Bd growth in cell-free supernatants (CFSs) from each temperature treatment. CFSs from 11 of 24 bacteria showed reduced anti-Bd activity in vitro when they were produced at cool temperatures similar to those encountered by the host species during population declines. Reduced anti-Bd activity of metabolites produced at low temperatures may, therefore, partially explain the association between Bd-driven declines and cool temperatures. We show that to avoid inconsistent antifungal activity, bacteria evaluated for use in chytridiomycosis biocontrol should be tested over a range of environmental temperatures spanning those likely to be encountered in the field. PMID:24941262

Daskin, Joshua H.; Bell, Sara C.; Schwarzkopf, Lin; Alford, Ross A.

2014-01-01

367

Cool temperatures reduce antifungal activity of symbiotic bacteria of threatened amphibians--implications for disease management and patterns of decline.  

PubMed

Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a widespread disease of amphibians responsible for population declines and extinctions. Some bacteria from amphibians' skins produce antimicrobial substances active against Bd. Supplementing populations of these cutaneous antifungal bacteria might help manage chytridiomycosis in wild amphibians. However, the activity of protective bacteria may depend upon environmental conditions. Biocontrol of Bd in nature thus requires knowledge of how environmental conditions affect their anti-Bd activity. For example, Bd-driven amphibian declines have often occurred at temperatures below Bd's optimum range. It is possible these declines occurred due to reduced anti-Bd activity of bacterial symbionts at cool temperatures. Better understanding of the effects of temperature on chytridiomycosis development could also improve risk evaluation for amphibian populations yet to encounter Bd. We characterized, at a range of temperatures approximating natural seasonal variation, the anti-Bd activity of bacterial symbionts from the skins of three species of rainforest tree frogs (Litoria nannotis, Litoria rheocola, and Litoria serrata). All three species declined during chytridiomycosis outbreaks in the late 1980s and early 1990s and have subsequently recovered to differing extents. We collected anti-Bd bacterial symbionts from frogs and cultured the bacteria at constant temperatures from 8 °C to 33 °C. Using a spectrophotometric assay, we monitored Bd growth in cell-free supernatants (CFSs) from each temperature treatment. CFSs from 11 of 24 bacteria showed reduced anti-Bd activity in vitro when they were produced at cool temperatures similar to those encountered by the host species during population declines. Reduced anti-Bd activity of metabolites produced at low temperatures may, therefore, partially explain the association between Bd-driven declines and cool temperatures. We show that to avoid inconsistent antifungal activity, bacteria evaluated for use in chytridiomycosis biocontrol should be tested over a range of environmental temperatures spanning those likely to be encountered in the field. PMID:24941262

Daskin, Joshua H; Bell, Sara C; Schwarzkopf, Lin; Alford, Ross A

2014-01-01

368

Lymphoid Antigens on Blast Cells in the Agranular Metamorphosis of Chronic Myelogenous Leukaemia  

Microsoft Academic Search

Undifferentiated blasts from a Ph’-positive chronic myelogenous leukaemia (CML) in terminal metamorphosis were reacted in an indirect ímmunofluo-rescence test with antilymphocytic globulins (AHLGs), raised against cultured lymphoblasts, thoracic duct and peripheral blood lymphocytes from healthy donors. After proper myeloid and\\/or monocytic absorptions the AHLGs interacted strongly with the undifferentiated blasts of CML, while this was not true for parallel controls

A. Bacigalupo; G. Santini; G. Piaggio; M. Risso; M. T. van Lint; M. Carella; E. E. Damasio; M. C. Raffo; A. M. Marmont

1978-01-01

369

On natural metamorphosis inducers of the cnidarians Hydractinia echinata (Hydrozoa) and Aurelia aurita (Scyphozoa)  

Microsoft Academic Search

Hydractinia echinata and Aurelia aurita produce motile larvae which undergo metamorphosis to sessile polyps when induced by external cues. The polyps are found at\\u000a restricted sites, A. aurita predominantly on rocks close to the shore, H. echinata on shells inhabited by hermit crabs. It has been argued that the differential distribution of the polyps in their natural\\u000a environment largely reflects

Michael Kroiher; Stefan Berking

1999-01-01

370

Effects of size at metamorphosis on stonefly fecundity, longevity, and reproductive success  

Microsoft Academic Search

Many organisms with complex life cycles show considerable variation in size and timing at metamorphosis. Adult males of Megarcyssignata (Plecoptera: Perlodidae) are significantly smaller than females and emerge before females (protandry) from two western Colorado\\u000a streams. During summer 1992 stoneflies from a trout stream emerged earlier in the season and at larger sizes than those from\\u000a a colder fishless stream,

Brad W. Taylor; Chester R. Anderson; Barbara L. Peckarsky

1998-01-01

371

Dendritic Remodeling and Growth of Motoneurons during Metamorphosis of Drosophila melanogaster  

Microsoft Academic Search

Insect motoneurons display dramatic dendritic plasticity during metamorphosis. Many larval motoneurons survive to adulthood but undergo dendritic regression and outgrowth as they are incorporated into developing circuits. This study explores the dendritic remodeling and development of Drosophila motoneu- rons MN1-MN5, which innervate indirect flight muscles of the adult. MN1-MN5 are persistent larval neurons exhibiting two distinct metamorphic histories. MN1-MN4 are

Christos Consoulas; Linda L. Restifo; Richard B. Levine

2002-01-01

372

Influence of bacteria and diatoms in biofilms on metamorphosis of the marine slipper limpet Crepidula onyx  

Microsoft Academic Search

Larvae of the slipper limpet Crepidula onyx metamorphose in response to marine biofilms. In this study, we investigated how the percentage of larval metamorphosis in\\u000a this species was affected by biofilms that differed in certain attributes. To manipulate bacterial and diatom cell densities\\u000a and community composition, we developed biofilms in the laboratory (1) at different temperatures (16, 23 and 30°C)

Jill Man-Ying Chiu; Vengatesen Thiyagarajan; Jan A. Pechenik; Oi-Shing Hung; Pei-Yuan Qian

2007-01-01

373

PCB Accumulation and Toxicokinetics in Amphibians: Accumulation Patterns' Regulation by Interspecific Differences and Toxicokinetics in Green Frogs (Rana clamitans) During Hibernation.  

E-print Network

??This thesis examined contaminant accumulation in amphibian young of year and elimination kinetics during amphibian hibernation. Chapter 2 evaluated PCB concentrations in four amphibian species… (more)

Angell, Robin

2009-01-01

374

Phylogenetically-Informed Priorities for Amphibian Conservation  

PubMed Central

The amphibian decline and extinction crisis demands urgent action to prevent further large numbers of species extinctions. Lists of priority species for conservation, based on a combination of species’ threat status and unique contribution to phylogenetic diversity, are one tool for the direction and catalyzation of conservation action. We describe the construction of a near-complete species-level phylogeny of 5713 amphibian species, which we use to create a list of evolutionarily distinct and globally endangered species (EDGE list) for the entire class Amphibia. We present sensitivity analyses to test the robustness of our priority list to uncertainty in species’ phylogenetic position and threat status. We find that both sources of uncertainty have only minor impacts on our ‘top 100‘ list of priority species, indicating the robustness of the approach. By contrast, our analyses suggest that a large number of Data Deficient species are likely to be high priorities for conservation action from the perspective of their contribution to the evolutionary history. PMID:22952807

Isaac, Nick J. B.; Redding, David W.; Meredith, Helen M.; Safi, Kamran

2012-01-01

375

Larger body size at metamorphosis enhances survival, growth and performance of young cane toads (Rhinella marina).  

PubMed

Body size at metamorphosis is a key trait in species (such as many anurans) with biphasic life-histories. Experimental studies have shown that metamorph size is highly plastic, depending upon larval density and environmental conditions (e.g. temperature, food supply, water quality, chemical cues from conspecifics, predators and competitors). To test the hypothesis that this developmental plasticity is adaptive, or to determine if inducing plasticity can be used to control an invasive species, we need to know whether or not a metamorphosing anuran's body size influences its subsequent viability. For logistical reasons, there are few data on this topic under field conditions. We studied cane toads (Rhinella marina) within their invasive Australian range. Metamorph body size is highly plastic in this species, and our laboratory studies showed that larger metamorphs had better locomotor performance (both on land and in the water), and were more adept at catching and consuming prey. In mark-recapture trials in outdoor enclosures, larger body size enhanced metamorph survival and growth rate under some seasonal conditions. Larger metamorphs maintained their size advantage over smaller siblings for at least a month. Our data support the critical but rarely-tested assumption that all else being equal, larger body size at metamorphosis is likely to enhance an individual's long term viability. Thus, manipulations to reduce body size at metamorphosis in cane toads may help to reduce the ecological impact of this invasive species. PMID:23922930

Cabrera-Guzmán, Elisa; Crossland, Michael R; Brown, Gregory P; Shine, Richard

2013-01-01

376

Larger Body Size at Metamorphosis Enhances Survival, Growth and Performance of Young Cane Toads (Rhinella marina)  

PubMed Central

Body size at metamorphosis is a key trait in species (such as many anurans) with biphasic life-histories. Experimental studies have shown that metamorph size is highly plastic, depending upon larval density and environmental conditions (e.g. temperature, food supply, water quality, chemical cues from conspecifics, predators and competitors). To test the hypothesis that this developmental plasticity is adaptive, or to determine if inducing plasticity can be used to control an invasive species, we need to know whether or not a metamorphosing anuran’s body size influences its subsequent viability. For logistical reasons, there are few data on this topic under field conditions. We studied cane toads (Rhinella marina) within their invasive Australian range. Metamorph body size is highly plastic in this species, and our laboratory studies showed that larger metamorphs had better locomotor performance (both on land and in the water), and were more adept at catching and consuming prey. In mark-recapture trials in outdoor enclosures, larger body size enhanced metamorph survival and growth rate under some seasonal conditions. Larger metamorphs maintained their size advantage over smaller siblings for at least a month. Our data support the critical but rarely-tested assumption that all else being equal, larger body size at metamorphosis is likely to enhance an individual’s long term viability. Thus, manipulations to reduce body size at metamorphosis in cane toads may help to reduce the ecological impact of this invasive species. PMID:23922930

Cabrera-Guzmán, Elisa; Crossland, Michael R.; Brown, Gregory P.; Shine, Richard

2013-01-01

377

Identification of Direct Thyroid Hormone Response Genes Reveals the Earliest Gene Regulation Programs during Frog Metamorphosis*  

PubMed Central

Thyroid hormone (T3) is essential for normal development and organ function throughout vertebrates. Its effects are mainly mediated through transcriptional regulation by T3 receptor (TR). The identification and characterization of the immediate early, direct target genes are thus of critical importance in understanding the molecular pathways induced by T3. Unfortunately, this has been hampered by the difficulty to study gene regulation by T3 in uterus-enclosed mammalian embryos. Here we used Xenopus metamorphosis as a model for vertebrate postembryonic development to identify direct T3 response genes in vivo. We took advantage of the ability to easily induce metamorphosis with physiological levels of T3 and to carry out microarray analysis in Xenopus laevis and genome-wide sequence analysis in Xenopus tropicalis. This allowed us to identify 188 up-regulated and 249 down-regulated genes by T3 in the absence of new protein synthesis in whole animals. We further provide evidence to show that these genes contain functional TREs that are bound by TR in tadpoles and that their promoters are regulated by TR in vivo. More importantly, gene ontology analysis showed that the direct up-regulated genes are enriched in categories important for transcriptional regulation and protein degradation-dependent signaling processes but not DNA replication. Our findings thus revealed the existence of interesting pathways induced by T3 at the earliest step of metamorphosis. PMID:19801647

Das, Biswajit; Heimeier, Rachel A.; Buchholz, Daniel R.; Shi, Yun-Bo

2009-01-01

378

Involvement of Wnt Signaling Pathways in the Metamorphosis of the Bryozoan Bugula neritina  

PubMed Central

In this study, we analyzed the metamorphosis of the marine bryozoan Bugula neritina. We observed the morphogenesis of the ancestrula. We defined three distinct pre-ancestrula stages based on the anatomy of the developing polypide and the overall morphology of pre-ancestrula. We then used an annotation based enrichment analysis tool to analyze the B. neritina transcriptome and identified over-representation of genes related to Wnt signaling pathways, suggesting its involvement in metamorphosis. Finally, we studied the temporal-spatial gene expression studies of several Wnt pathway genes. We found that one of the Wnt ligand, BnWnt10, was expressed spatially opposite to the Wnt antagonist BnsFRP within the blastemas, which is the presumptive polypide. Down-stream components of the canonical Wnt signaling pathway were exclusively expressed in the blastemas. Bn?catenin and BnFz5/8 were exclusively expressed in the blastemas throughout the metamorphosis. Based on the genes expression patterns, we propose that BnWnt10 and BnsFRP may relate to the patterning of the polypide, in which the two genes served as positional signals and contributed to the polarization of the blastemas. Another Wnt ligand, BnWnt6, was expressed in the apical part of the pre-ancestrula epidermis. Overall, our findings suggest that the Wnt signaling pathway may be important to the pattern formation of polypide and the development of epidermis. PMID:22448242

Wong, Yue Him; Wang, Hao; Ravasi, Timothy; Qian, Pei-Yuan

2012-01-01

379

Lipid peroxidation and antioxidant defence status during larval development and metamorphosis of giant prawn, Macrobrachium rosenbergii.  

PubMed

In the present communication we studied the involvement of reactive oxygen species and alteration in antioxidant defence status during larval development and metamorphosis of giant prawn, Macrobrachium rosenbergii. Overall results indicate that there was a decline in endogenous lipid peroxidation level during larval development. Activity of superoxide dismutase was the lowest in early larval stages (Zoea-I and II) and thereafter increased in V and VI stages, followed by a decrease in the subsequent larval stages. Catalase and glutathione peroxidase did not exhibit specific pattern of changes during development. Reduced glutathione content exhibited an incremental increase during larval progression until metamorphosis. Ascorbic acid content of the larval tissue remained unaltered during development but a sharp fall was marked in its content in the post-larvae. Hence it is concluded that early larvae face high oxidative stress as evident from the high content of thiobarbituric acid reactive substances. This may be due to direct exposure of larvae to ambient oxygen of the water as well as their low antioxidant potential. However, during development with the augmentation in antioxidant reserve of the larval tissues a diminution in the oxidative stress was recorded. Thus it is presumed that antioxidant defences play an important role in providing protection to the developing larvae from oxidative assault during larval progression and metamorphosis. PMID:12927897

Dandapat, Jagneshwar; Chainy, Gagan B N; Rao, K Janardhana

2003-07-01

380

Figure 7-1: Amphibian locator map ShAwn R. KuchtA  

E-print Network

Figure 7-1: Amphibian locator map #12;chapter 7 Amphibians ShAwn R. KuchtA I mAgine you ARe w or feathers, and it isn't a fish, there are only two options: it is either a reptile or an amphibian lacks scales and is smooth and moist, it is an amphibian (some amphibians have roughened or "warty" skin

Kuchta, Shawn R.

381

Amphibian skin may select for rare environmental microbes.  

PubMed

Host-microbe symbioses rely on the successful transmission or acquisition of symbionts in each new generation. Amphibians host a diverse cutaneous microbiota, and many of these symbionts appear to be mutualistic and may limit infection by the chytrid fungus, Batrachochytrium dendrobatidis, which has caused global amphibian population declines and extinctions in recent decades. Using bar-coded 454 pyrosequencing of the 16S rRNA gene, we addressed the question of symbiont transmission by examining variation in amphibian skin microbiota across species and sites and in direct relation to environmental microbes. Although acquisition of environmental microbes occurs in some host-symbiont systems, this has not been extensively examined in free-living vertebrate-microbe symbioses. Juvenile bullfrogs (Rana catesbeiana), adult red-spotted newts (Notophthalmus viridescens), pond water and pond substrate were sampled at a single pond to examine host-specificity and potential environmental transmission of microbiota. To assess population level variation in skin microbiota, adult newts from two additional sites were also sampled. Cohabiting bullfrogs and newts had distinct microbial communities, as did newts across the three sites. The microbial communities of amphibians and the environment were distinct; there was very little overlap in the amphibians' core microbes and the most abundant environmental microbes, and the relative abundances of OTUs that were shared by amphibians and the environment were inversely related. These results suggest that, in a host species-specific manner, amphibian skin may select for microbes that are generally in low abundance in the environment. PMID:24858782

Walke, Jenifer B; Becker, Matthew H; Loftus, Stephen C; House, Leanna L; Cormier, Guy; Jensen, Roderick V; Belden, Lisa K

2014-11-01

382

Facility design and associated services for the study of amphibians.  

PubMed

The role of facilities and associated services for amphibians has recently undergone diversification. Amphibians traditionally used as research models adjust well to captivity and thrive with established husbandry techniques. However, it is now necessary to maintain hundreds of novel amphibian species in captive breeding, conservation research, and biomedical research programs. These diverse species have a very wide range of husbandry requirements, and in many cases the ultimate survival of threatened species will depend on captive populations. Two critical factors have emerged in the maintenance of amphibians, stringent quarantine and high-quality water. Because exotic diseases such as chytridiomycosis have devastated both natural and captive populations of amphibians, facilities must provide stringent quarantine. The provision of high-quality water is also essential to maintain amphibian health and condition due to the intimate physiological relationship of amphibians to their aquatic environment. Fortunately, novel technologies backed by recent advances in the scientific knowledge of amphibian biology and disease management are available to overcome these challenges. For example, automation can increase the reliability of quarantine and maintain water quality, with a corresponding decrease in handling and the associated disease-transfer risk. It is essential to build facilities with appropriate nontoxic waterproof materials and to provide quarantined amphibian rooms for each population. Other spaces and services include live feed rooms, quarantine stations, isolation rooms, laboratory space, technical support systems, reliable energy and water supplies, high-quality feed, and security. Good husbandry techniques must include reliable and species-specific management by trained staff members who receive support from the administration. It is possible to improve husbandry techniques for many species by sharing knowledge through common information systems. Overall, good facility design corresponds to the efficient use of space, personnel, energy, materials, and other resources. PMID:17592183

Browne, Robert K; Odum, R Andrew; Herman, Timothy; Zippel, Kevin

2007-01-01

383

Modeling effects of conservation grassland losses on amphibian habitat  

USGS Publications Warehouse

Amphibians provide many ecosystem services valued by society. However, populations have declined globally with most declines linked to habitat change. Wetlands and surrounding terrestrial grasslands form habitat for amphibians in the North American Prairie Pothole Region (PPR). Wetland drainage and grassland conversion have destroyed or degraded much amphibian habitat in the PPR. However, conservation grasslands can provide alternate habitat. In the United States, the Conservation Reserve Program (CRP) is the largest program maintaining grasslands on agricultural lands. We used an ecosystem services model (InVEST) parameterized for the PPR to quantify amphibian habitat over a six-year period (2007–2012). We then quantified changes in availability of amphibian habitat under various land-cover scenarios representing incremental losses (10%, 25%, 50%, 75%, and 100%) of CRP grasslands from 2012 levels. The area of optimal amphibian habitat in the four PPR ecoregions modeled (i.e., Northern Glaciated Plains, Northwestern Glaciated Plains, Lake Agassiz Plain, Des Moines Lobe) declined by approximately 22%, from 3.8 million ha in 2007 to 2.9 million ha in 2012. These losses were driven by the conversion of CRP grasslands to croplands, primarily for corn and soybean production. Our modeling identified an additional 0.8 million ha (26%) of optimal amphibian habitat that would be lost if remaining CRP lands are returned to crop production. An economic climate favoring commodity production over conservation has resulted in substantial losses of amphibian habitat across the PPR that will likely continue into the future. Other regions of the world face similar challenges to maintaining amphibian habitats.

Mushet, David M.; Neau, Jordan L.; Euliss, Ned H.

2014-01-01

384

Cellulase Assays  

NASA Astrophysics Data System (ADS)

Cellulose is a heterogeneous polysaccharide, and its enzymatic hydrolysis requires endoglucanase, exoglucanase (cellobiohydrolase), and ?-glucosidase to work together. We summarize the most commonly used assays for individual enzymes and cellulase mixture.

Zhang, Y. H. Percival; Hong, Jiong; Ye, Xinhao

385

FMAj: a tool for high content analysis of muscle dynamics in Drosophila metamorphosis  

PubMed Central

Background During metamorphosis in Drosophila melanogaster, larval muscles undergo two different developmental fates; one population is removed by cell death, while the other persistent subset undergoes morphological remodeling and survives to adulthood. Thanks to the ability to perform live imaging of muscle development in transparent pupae and the power of genetics, metamorphosis in Drosophila can be used as a model to study the regulation of skeletal muscle mass. However, time-lapse microscopy generates sizeable image data that require new tools for high throughput image analysis. Results We performed targeted gene perturbation in muscles and acquired 3D time-series images of muscles in metamorphosis using laser scanning confocal microscopy. To quantify the phenotypic effects of gene perturbations, we designed the Fly Muscle Analysis tool (FMAj) which is based on the ImageJ and MySQL frameworks for image processing and data storage, respectively. The image analysis pipeline of FMAj contains three modules. The first module assists in adding annotations to time-lapse datasets, such as genotypes, experimental parameters and temporal reference points, which are used to compare different datasets. The second module performs segmentation and feature extraction of muscle cells and nuclei. Users can provide annotations to the detected objects, such as muscle identities and anatomical information. The third module performs comparative quantitative analysis of muscle phenotypes. We applied our tool to the phenotypic characterization of two atrophy related genes that were silenced by RNA interference. Reduction of Drosophila Tor (Target of Rapamycin) expression resulted in enhanced atrophy compared to control, while inhibition of the autophagy factor Atg9 caused suppression of atrophy and enlarged muscle fibers of abnormal morphology. FMAj enabled us to monitor the progression of atrophic and hypertrophic phenotypes of individual muscles throughout metamorphosis. Conclusions We designed a new tool to visualize and quantify morphological changes of muscles in time-lapse images of Drosophila metamorphosis. Our in vivo imaging experiments revealed that evolutionarily conserved genes involved in Tor signalling and autophagy, perform similar functions in regulating muscle mass in mammals and Drosophila. Extending our approach to a genome-wide scale has the potential to identify new genes involved in muscle size regulation. PMID:25521203

2014-01-01

386

ASSESSMENT OF THE RISK OF SOLAR ULTRAVIOLET RADIATION TO AMPHIBIANS. II: IN SITU CHARACTERIZATION OF SOLAR ULTRAVIOLET RADIATION IN AMPHIBIAN HABITATS  

EPA Science Inventory

Ultraviolet B (UVB) radiation has been hypothesized as a potential cause of amphibian population declines and increased incidences of malformations. Realistic studies documenting UV irradiance or dose have rarely been conducted in wetlands used by amphibians. We demonstrate that ...

387

Global warming and extinction risks for amphibians in Madagascar, an Franco Andreone, Museo Regionale di Scienze Naturali and Amphibian Specialist Group /  

E-print Network

Global warming and extinction risks for amphibians in Madagascar, an overview Franco Andreone, Museo Regionale di Scienze Naturali and Amphibian Specialist Group / Madagascar, Via G. Giolitti, 36, I.andreone@gmail.com The amphibians of Madagascar represent one of the most extraordinary biodiversity off- shots, with around 240

Andreone, Franco

388

Amphibian fertilization and development in microgravity  

NASA Technical Reports Server (NTRS)

An experiment investigating the effects of gravity on embryonic development in amphibians is proposed. The planned procedures for the preparation of the frog eggs for launching in the Space Shuttle, for the injection of the eggs with gonadotropin, for the insertion of the eggs into egg chambers, for the storage of one of the chambers in a microgravity area and the second into a centrifuge, and for the fertilization of the eggs are described. The later organogenesis, swimming behavior, cytoplasmic components, cellular formation, neural plate and archenteron expansion, and allometry and expansion of the organ systems will be examined. Normal morphology for embryos and tadpoles developing at microgravity and the formation of the neural plate opposite the sperm entry point meridian are predicted.

Souza, K. A.; Black, S. D.

1985-01-01

389

Ambient UV-B radiation causes deformities in amphibian embryos  

PubMed Central

There has been a great deal of recent attention on the suspected increase in amphibian deformities. However, most reports of amphibian deformities have been anecdotal, and no experiments in the field under natural conditions have been performed to investigate this phenomenon. Under laboratory conditions, a variety of agents can induce deformities in amphibians. We investigated one of these agents, UV-B radiation, in field experiments, as a cause for amphibian deformities. We monitored hatching success and development in long-toed salamanders under UV-B shields and in regimes that allowed UV-B radiation. Embryos under UV-B shields had a significantly higher hatching rate and fewer deformities, and developed more quickly than those exposed to UV-B. Deformities may contribute directly to embryo mortality, and they may affect an individual’s subsequent survival after hatching. PMID:9391095

Blaustein, Andrew R.; Kiesecker, Joseph M.; Chivers, Douglas P.; Anthony, Robert G.

1997-01-01

390

Checklist of Helminth parasites of Amphibians from South America.  

PubMed

Parasitological studies on helminths of amphibians in South America have increased in the past few years. Here, we present a list with summarized data published on helminths of South American amphibians from 1925 to 2012, including a list of helminth parasites, host species, and geographic records. We found 194 reports of helminths parasitizing 185 amphibian species from eleven countries: Argentina, Brazil, Chile, Colombia, Equador, French Guyana, Guyana, Paraguay, Peru, Uruguay and Venezuela. Helminth biodiversity includes 278 parasite species of the groups Acanthocephala, Nematoda, Cestoda, Monogenea and Trematoda. A list of helminth parasite species per host, and references are also presented. This contribution aims to document the biodiversity of helminth parasites in South American amphibians, as well as identify gaps in our knowledge, which in turn may guide subsequent studies.  PMID:25082165

Campião, Karla Magalhães; Morais, Drausio Honorio; Dias, Olívia Tavares; Aguiar, Aline; Toledo, Gislayne; Tavares, Luiz Eduardo Roland; Da Silva, Reinaldo José

2014-01-01

391

Metabolism of pesticides after dermal exposure to amphibians  

EPA Science Inventory

Understanding how pesticide exposure to non-target species influences toxicity is necessary to accurately assess the ecological risks these compounds pose. Aquatic, terrestrial, and arboreal amphibians are often exposed to pesticides during their agricultural application resultin...

392

A database of life-history traits of European amphibians  

PubMed Central

Abstract In the current context of climate change and landscape fragmentation, efficient conservation strategies require the explicit consideration of life history traits. This is particularly true for amphibians, which are highly threatened worldwide, composed by more than 7400 species, which is constitute one of the most species-rich vertebrate groups. The collection of information on life history traits is difficult due to the ecology of species and remoteness of their habitats. It is therefore not surprising that our knowledge is limited, and missing information on certain life history traits are common for in this species group. We compiled data on amphibian life history traits from literature in an extensive database with morphological and behavioral traits, habitat preferences and movement abilities for 86 European amphibian species (50 Anuran and 36 Urodela species). When it were available, we reported data for males, females, juveniles and tadpoles. Our database may serve as an important starting point for further analyses regarding amphibian conservation. PMID:25425939

Moulherat, Sylvain; Calvez, Olivier; Stevens, Virginie M; Clobert, Jean; Schmeller, Dirk S

2014-01-01

393

CHARACTERIZATION OF RELATIVE SENSITIVITY OF AMPHIBIANS TO ULTRAVIOLET RADIATION  

EPA Science Inventory

Different studies have demonstrated that solar ultraviolet (UV) radiation can adversely affect survival and development of embryonic and larval amphibians. However, because of among-laboratory variations in exposure profiles (artificial vs. natural sunlight; natural sunlight at d...

394

Ambient UV-B radiation causes deformities in amphibian embryos  

USGS Publications Warehouse

There has been a great deal of recent attention on the suspected increase in amphibian deformities. However, most reports of amphibian deformities have been anecdotal, and no experiments in the field under natural conditions have been performed to investigate this phenomenon. Under laboratory conditions, a variety of agents can induce deformities in amphibians. We investigated one of these agents, UV-B radiation, in field experiments, as a cause for amphibian deformities. We monitored hatching success and development in long-toed salamanders under UV-B shields and in regimes that allowed UV-B radiation. Embryos under UV-B shields had a significantly higher hatching rate and fewer deformities, and developed more quickly than those exposed to UV-B. Deformities may contribute directly to embryo mortality, and they may affect an individual's subsequent survival after hatching.

Blaustein, A.R.; Kiesecker, J.M.; Chivers, D.P.; Anthony, R.G.

1997-01-01

395

CHARACTERIZATION OF RELATIVE SENSITIVITY OF AMPHIBIANS TO ULTRA VIOLET RADIATION  

EPA Science Inventory

Different studies have demonstrated that solar ultraviolet (UV) radiation can adversely affect survival and development of embryonic and larval amphibians. However, because of among-laboratory variations in exposure profiles (artificial vs. natural sunlight; natural sunlight at d...

396

ALIEN SPECIES: THEIR ROLE IN AMPHIBIAN POPULATION DECLINES AND RESTORATION  

EPA Science Inventory

Alien species (also referred to as exotic, invasive, introduced, or normative species) have been implicated as causal agents in population declines of many amphibian species. Herein, we evaluate the relative contributions of alien species and other factors in adversely affecting ...

397

Herpetological Review 44(4), 2013 AMPHIBIAN DISEASES 611  

E-print Network

­614. © 2013 by Society for the Study of Amphibians and Reptiles Detection of Batrachochytrium dendrobatidis Batrachochy- trium dendrobatidis (Bd) has been reported from southern, east- ern, and central parts

Storfer, Andrew

398

Herpetological Review 43(3), 2012 AMPHIBIAN DISEASES 427  

E-print Network

of Amphibians and Reptiles Batrachochytrium dendrobatidis and Ranavirus in Anurans Inhabiting Decorative Koi) and Batracho- chytrium dendrobatidis (Bd) has been reported from several lo- cations in Minnesota (Rodriguez et

Gray, Matthew

399

2D gel-based proteome and phosphoproteome analysis during larval metamorphosis in two major marine biofouling invertebrates.  

PubMed

Larvae of some benthic invertebrates respond (metamorphose or not) to chemical cues within minutes or hours and often without excessive transcription or translation. Although protein phosphorylation is one of the most important molecular switching mechanisms that govern variety of rapid cellular responses in higher organisms, this is the first study to analyze the global protein expression and protein phosphorylation status during larval metamorphosis in two major marine biofouling invertebrates (a bryozoan Bugula neritina and a barnacle Balanus amphitrite). Results indicate that larval proteomic response to metamorphosis (inhibiton or induction) involves substantial change in the phosphorylation status of proteins rather than de novo protein synthesis. An abundantly expressed and an unnamed phosphoprotein that appears to play key regulatory role in larval metamorphosis was identified. When larvae of bryozoan and barnacle were challenged with a metamorphosis (and kinase) inhibitor, the genistein, the number of phosphoproteins in bryozoan were substantially reduced but drastically increased in barnacle. Taken together, this is the first time that the usefulness of employing 2DE-based proteomic and phosphoproteomic approaches was demonstrated for us to understand the molecular mechanisms of larval metamorphosis and to study the mode-of-action of chemical cues in marine organisms. PMID:19341272

Thiyagarajan, Vengatesen; Wong, Tim; Qian, Pei-Yuan

2009-06-01

400

Focal Review: The Origin(s) of Modern Amphibians  

Microsoft Academic Search

The recent description of the stem batrachian Gerobatrachus has changed the terms of the ongoing debate on the origin of extant amphibians (Lissamphibia: frogs, salamanders, and the\\u000a limbless caecilians). This important fossil, through a shared mosaic of unique derived salientian and urodele characters,\\u000a links frogs and salamanders with an archaic group of fossil amphibians known as amphibamid temnospondyls. The present

Jason S. Anderson

2008-01-01

401

Consequences of habitat loss and fragmentation for wetland amphibian assemblages  

Microsoft Academic Search

Landscape-level variables operating at multiple spatial scales likely influence wetland amphibian assemblages but have not\\u000a been investigated in detail. We examined the significance of habitat loss and fragmentation, as well as selected within-wetland\\u000a conditions, affecting amphibian assemblages in twenty-one glacial marshes. Wetlands were located within urban and agricultural\\u000a regions of central and southwestern Minnesota, USA and were distributed across two

Richard M. Lehtinen; Susan M. Galatowitsch; John R. Tester

1999-01-01

402

Toxicity of road salt to Nova Scotia amphibians  

Microsoft Academic Search

The deposition of chemical pollutants into roadside wetlands from runoff is a current environmental concern. In northern latitudes, a major pollutant in runoff water is salt (NaCl), used as de-icing agents. In this study, 26 roadside ponds were surveyed for amphibian species richness and chloride concentration. Acute toxicity tests (LC50) were performed on five locally common amphibian species using a

Sara J. Collins; Ronald W. Russell

2009-01-01

403

Global patterns of diversification in the history of modern amphibians  

PubMed Central

The fossil record of modern amphibians (frogs, salamanders, and caecilians) provides no evidence for major extinction or radiation episodes throughout most of the Mesozoic and early Tertiary. However, long-term gradual diversification is difficult to reconcile with the sensitivity of present-day amphibian faunas to rapid ecological changes and the incidence of similar environmental perturbations in the past that have been associated with high turnover rates in other land vertebrates. To provide a comprehensive overview of the history of amphibian diversification, we constructed a phylogenetic timetree based on a multigene data set of 3.75 kb for 171 species. Our analyses reveal several episodes of accelerated amphibian diversification, which do not fit models of gradual lineage accumulation. Global turning points in the phylogenetic and ecological diversification occurred after the end-Permian mass extinction and in the late Cretaceous. Fluctuations in amphibian diversification show strong temporal correlation with turnover rates in amniotes and the rise of angiosperm-dominated forests. Approximately 86% of modern frog species and >81% of salamander species descended from only five ancestral lineages that produced major radiations in the late Cretaceous and early Tertiary. This proportionally late accumulation of extant lineage diversity contrasts with the long evolutionary history of amphibians but is in line with the Tertiary increase in fossil abundance toward the present. PMID:17213318

Roelants, Kim; Gower, David J.; Wilkinson, Mark; Loader, Simon P.; Biju, S. D.; Guillaume, Karen; Moriau, Linde; Bossuyt, Franky

2007-01-01

404

Global patterns of diversification in the history of modern amphibians.  

PubMed

The fossil record of modern amphibians (frogs, salamanders, and caecilians) provides no evidence for major extinction or radiation episodes throughout most of the Mesozoic and early Tertiary. However, long-term gradual diversification is difficult to reconcile with the sensitivity of present-day amphibian faunas to rapid ecological changes and the incidence of similar environmental perturbations in the past that have been associated with high turnover rates in other land vertebrates. To provide a comprehensive overview of the history of amphibian diversification, we constructed a phylogenetic timetree based on a multigene data set of 3.75 kb for 171 species. Our analyses reveal several episodes of accelerated amphibian diversification, which do not fit models of gradual lineage accumulation. Global turning points in the phylogenetic and ecological diversification occurred after the end-Permian mass extinction and in the late Cretaceous. Fluctuations in amphibian diversification show strong temporal correlation with turnover rates in amniotes and the rise of angiosperm-dominated forests. Approximately 86% of modern frog species and >81% of salamander species descended from only five ancestral lineages that produced major radiations in the late Cretaceous and early Tertiary. This proportionally late accumulation of extant lineage diversity contrasts with the long evolutionary history of amphibians but is in line with the Tertiary increase in fossil abundance toward the present. PMID:17213318

Roelants, Kim; Gower, David J; Wilkinson, Mark; Loader, Simon P; Biju, S D; Guillaume, Karen; Moriau, Linde; Bossuyt, Franky

2007-01-16

405

Tropical amphibian populations experience higher disease risk in natural habitats  

PubMed Central

Habitat loss and disease are main drivers of global amphibian declines, yet the interaction between them remains largely unexplored. Here we show that paradoxically, habitat loss is negatively associated with occurrence, prevalence, and infection intensity of the chytrid fungus Batrachochytrium dendrobatidis (Bd) in amphibian populations in the tropics. At a large spatial scale, increased habitat loss predicted lower disease risk in amphibian populations across Costa Rica and eastern Australia, even after jointly considering the effect of potential biotic and abiotic correlates. Lower host-species richness and suboptimal microclimates for Bd in disturbed habitats are potential mechanisms underlying this pattern. Furthermore, we found that anthropogenic deforestation practices biased to lowlands and natural vegetation remaining in inaccessible highlands explain increased Bd occurrence at higher elevations. At a smaller spatial scale, holding constant elevation, latitude, and macroclimate, we also found a negative relationship between habitat loss, and both Bd prevalence and infection intensity in frog populations in two landscapes of the Brazilian Atlantic Forest. Our results indicate that amphibians will be disproportionately affected by emerging diseases in pristine environments, and that, paradoxically, disturbed habitats may act as shelters from disease, but only for the very few species that can tolerate deforestation. Thus, tropical amphibian faunas are threatened both by destruction of natural habitats as well as increased disease in pristine forests. To curb further extinctions and develop effective mitigation and restoration programs we must look to interactions between habitat loss and disease, the two main factors at the root of global amphibian declines. PMID:21628560

Becker, C. Guilherme; Zamudio, Kelly R.

2011-01-01

406

Population differentiation of temperate amphibians in unpredictable environments.  

PubMed

Amphibians are a globally distributed and diverse lineage, but much of our current understanding of their population genetic structure comes from studies in mesic temperate habitats. We characterize the population genetic structure of two sympatric explosive breeding amphibians in the southwestern deserts of the United States: the Great Plains toad (Anaxyrus cognatus) and Couch's spadefoot toad (Scaphiopus couchii). For both species, we find limited genetic differentiation even between populations in adjacent valleys separated by dispersal barriers such as mountainous habitats. To understand how population genetic patterns in these two arid-adapted species compare to taxa in more mesic environments, we computed a standardized measure of population differentiation for A. cognatus, S. couchii, and for pond-breeding amphibians that inhabit mesic temperate environments. Our results indicate that the arid-adapted species have lower population genetic structure at fine and moderate scales than most other amphibian species we surveyed. We hypothesize that stochasticity in the availability of appropriate breeding sites as well as landscape homogeneity may result in increased population connectivity in desert-adapted frogs. Future work examining fine-scale population structure in amphibians from a diversity of habitats will test the generality of our findings. Intraspecific comparisons among localities with varied seasonality and habitats will be particularly useful for investigating the interaction between species-typical population dynamics and environmental characteristics as determinants of population connectivity in pond-breeding amphibians. PMID:19573030

Chan, Lauren M; Zamudio, Kelly R

2009-08-01

407

Canadian Amphibian and Reptile Conservation Network (CARCN) = Reseau Canadien de Conservation des Amphibiens et des Reptiles (RCCAR)  

NSDL National Science Digital Library

The Canadian Amphibian and Reptile Conservation Network (CARCN) provides information on the biology and conservation of Canada's frogs, toads, and salamanders. Four sections form the substance of the site: Amphibian Biology, Key to Canadian Amphibians, Tour of Canadian Amphibians, and Amphibian Decline Issues. Descriptive information includes frog calls and distribution maps, as well as photographs of species. Additional sections describe CARCN and challenge users to test their knowledge via The Great Canadian Amphibian & Reptile Quiz.

1998-01-01

408

Plasticity of the duration of metamorphosis in the African clawed toad  

E-print Network

by body size, but independent of this effect, it was strongly influenced by environmental temperature of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, Graham Kerr Building amphibian Xenopus laevis was sensitive to environmental temperature. Metamorphic duration was influenced

Gray, Matthew

409

Control of target gene specificity during metamorphosis by the steroid response gene E93  

PubMed Central

Hormonal control of sexual maturation is a common feature in animal development. A particularly dramatic example is the metamorphosis of insects, in which pulses of the steroid hormone ecdysone drive the wholesale transformation of the larva into an adult. The mechanisms responsible for this transformation are not well understood. Work in Drosophila indicates that the larval and adult forms are patterned by the same underlying sets of developmental regulators, but it is not understood how the same regulators pattern two distinct forms. Recent studies indicate that this ability is facilitated by a global change in the responsiveness of target genes during metamorphosis. Here we show that this shift is controlled in part by the ecdysone-induced transcription factor E93. Although long considered a dedicated regulator of larval cell death, we find that E93 is expressed widely in adult cells at the pupal stage and is required for many patterning processes at this time. To understand the role of E93 in adult patterning, we focused on a simple E93-dependent process, the induction of the Dll gene within bract cells of the pupal leg by EGF receptor signaling. In this system, we show that E93 functions to cause Dll to become responsive to EGF receptor signaling. We demonstrate that E93 is both necessary and sufficient for directing this switch. E93 likely controls the responsiveness of many other target genes because it is required broadly for patterning during metamorphosis. The wide conservation of E93 orthologs suggests that similar mechanisms control life-cycle transitions in other organisms, including vertebrates. PMID:22308414

Mou, Xiaochun; Duncan, Dianne M.; Baehrecke, Eric H.; Duncan, Ian

2012-01-01

410

Turbine sound may influence the metamorphosis behaviour of estuarine crab megalopae.  

PubMed

It is now widely accepted that a shift towards renewable energy production is needed in order to avoid further anthropogenically induced climate change. The ocean provides a largely untapped source of renewable energy. As a result, harvesting electrical power from the wind and tides has sparked immense government and commercial interest but with relatively little detailed understanding of the potential environmental impacts. This study investigated how the sound emitted from an underwater tidal turbine and an offshore wind turbine would influence the settlement and metamorphosis of the pelagic larvae of estuarine brachyuran crabs which are ubiquitous in most coastal habitats. In a laboratory experiment the median time to metamorphosis (TTM) for the megalopae of the crabs Austrohelice crassa and Hemigrapsus crenulatus was significantly increased by at least 18 h when exposed to either tidal turbine or sea-based wind turbine sound, compared to silent control treatments. Contrastingly, when either species were subjected to natural habitat sound, observed median TTM decreased by approximately 21-31% compared to silent control treatments, 38-47% compared to tidal turbine sound treatments, and 46-60% compared to wind turbine sound treatments. A lack of difference in median TTM in A. crassa between two different source levels of tidal turbine sound suggests the frequency composition of turbine sound is more relevant in explaining such responses rather than sound intensity. These results show that estuarine mudflat sound mediates natural metamorphosis behaviour in two common species of estuarine crabs, and that exposure to continuous turbine sound interferes with this natural process. These results raise concerns about the potential ecological impacts of sound generated by renewable energy generation systems placed in the nearshore environment. PMID:23240063

Pine, Matthew K; Jeffs, Andrew G; Radford, Craig A

2012-01-01

411

Turbine Sound May Influence the Metamorphosis Behaviour of Estuarine Crab Megalopae  

PubMed Central

It is now widely accepted that a shift towards renewable energy production is needed in order to avoid further anthropogenically induced climate change. The ocean provides a largely untapped source of renewable energy. As a result, harvesting electrical power from the wind and tides has sparked immense government and commercial interest but with relatively little detailed understanding of the potential environmental impacts. This study investigated how the sound emitted from an underwater tidal turbine and an offshore wind turbine would influence the settlement and metamorphosis of the pelagic larvae of estuarine brachyuran crabs which are ubiquitous in most coastal habitats. In a laboratory experiment the median time to metamorphosis (TTM) for the megalopae of the crabs Austrohelice crassa and Hemigrapsus crenulatus was significantly increased by at least 18 h when exposed to either tidal turbine or sea-based wind turbine sound, compared to silent control treatments. Contrastingly, when either species were subjected to natural habitat sound, observed median TTM decreased by approximately 21–31% compared to silent control treatments, 38–47% compared to tidal turbine sound treatments, and 46–60% compared to wind turbine sound treatments. A lack of difference in median TTM in A. crassa between two different source levels of tidal turbine sound suggests the frequency composition of turbine sound is more relevant in explaining such responses rather than sound intensity. These results show that estuarine mudflat sound mediates natural metamorphosis behaviour in two common species of estuarine crabs, and that exposure to continuous turbine sound interferes with this natural process. These results raise concerns about the potential ecological impacts of sound generated by renewable energy generation systems placed in the nearshore environment. PMID:23240063

Pine, Matthew K.; Jeffs, Andrew G.; Radford, Craig A.

2012-01-01

412

Transcription factor E93 specifies adult metamorphosis in hemimetabolous and holometabolous insects.  

PubMed

All immature animals undergo remarkable morphological and physiological changes to become mature adults. In winged insects, metamorphic changes either are limited to a few tissues (hemimetaboly) or involve a complete reorganization of most tissues and organs (holometaboly). Despite the differences, the genetic switch between immature and adult forms in both types of insects relies on the disappearance of the antimetamorphic juvenile hormone (JH) and the transcription factors Krüppel-homolog 1 (Kr-h1) and Broad-Complex (BR-C) during the last juvenile instar. Here, we show that the transcription factor E93 is the key determinant that promotes adult metamorphosis in both hemimetabolous and holometabolous insects, thus acting as the universal adult specifier. In the hemimetabolous insect Blattella germanica, BgE93 is highly expressed in metamorphic tissues, and RNA interference (RNAi)-mediated knockdown of BgE93 in the nymphal stage prevented the nymphal-adult transition, inducing endless reiteration of nymphal development, even in the absence of JH. We also find that BgE93 down-regulated BgKr-h1 and BgBR-C expression during the last nymphal instar of B. germanica, a key step necessary for proper adult differentiation. This essential role of E93 is conserved in holometabolous insects as TcE93 RNAi in Tribolium castaneum prevented pupal-adult transition and produced a supernumerary second pupa. In this beetle, TcE93 also represses expression of TcKr-h1 and TcBR-C during the pupal stage. Similar results were obtained in the more derived holometabolous insect Drosophila melanogaster, suggesting that winged insects use the same regulatory mechanism to promote adult metamorphosis. This study provides an important insight into the understanding of the molecular basis of adult metamorphosis. PMID:24778249

Ureña, Enric; Manjón, Cristina; Franch-Marro, Xavier; Martín, David

2014-05-13

413

Post-Embryonic Transcriptomes of the Prawn Macrobrachium rosenbergii: Multigenic Succession through Metamorphosis  

PubMed Central

Like many metazoans, the freshwater prawn Macrobrachium rosenbergii begins its post-embryonic life with a set of morphologically distinct planktonic larval stages, followed by a benthic post-larval stage during which the maturing organism differs from the larvae both ecologically and physiologically. Understanding of the molecular basis underlying morphogenesis in crustaceans is limited to the observation that methyl farnesoate, the non-epoxidated form of the insect juvenile hormone, acts as the active crustacean juvenoid. Molt steroids were also linked to morphogenesis and several other molecular pathways, such as Hedgehog and Wnt, are known to underlie morphogenesis in all metazoans examined and, as such, are thought to do the same in crustaceans. Using next generation sequencing, we deep-sequenced the transcriptomes of several larval and post-larval stages. De novo assembly, followed by bioinformatics analysis, revealed that many novel transcripts are over-expressed in either larvae- or post-larvae-stage prawn, shedding light on the molecular basis underlying M. rosenbergii metamorphosis. Fast larval molting rates and periodic morphological changes were reflected in over-expression of transcripts annotated to the cell cycle, DNA replication and morphogenic pathways (i.e., Hedgehog and Wnt). Further characterization of transcripts assigned to morphogenic pathways by real-time RT-PCR reconfirmed their over-expression in larvae, albeit with a more complex expression pattern when examined in the individual developmental stages. The expression level of an orthologue of cytochrome P450, 15A1, known to epoxidize methyl farnesoate in insects, was increased in the late larval and early post-larval stages, in accordance with the role of methyl farnesoate in crustacean metamorphosis. This study exemplifies the applicability of a high-throughput sequencing approach for studying complex traits, including metamorphosis, providing new insight into this unexplored area of crustacean research. PMID:23372848

Ventura, Tomer; Manor, Rivka; Aflalo, Eliahu D.; Chalifa-Caspi, Vered; Weil, Simy; Sharabi, Omri; Sagi, Amir

2013-01-01

414

Post-embryonic transcriptomes of the prawn Macrobrachium rosenbergii: multigenic succession through metamorphosis.  

PubMed

Like many metazoans, the freshwater prawn Macrobrachium rosenbergii begins its post-embryonic life with a set of morphologically distinct planktonic larval stages, followed by a benthic post-larval stage during which the maturing organism differs from the larvae both ecologically and physiologically. Understanding of the molecular basis underlying morphogenesis in crustaceans is limited to the observation that methyl farnesoate, the non-epoxidated form of the insect juvenile hormone, acts as the active crustacean juvenoid. Molt steroids were also linked to morphogenesis and several other molecular pathways, such as Hedgehog and Wnt, are known to underlie morphogenesis in all metazoans examined and, as such, are thought to do the same in crustaceans. Using next generation sequencing, we deep-sequenced the transcriptomes of several larval and post-larval stages. De novo assembly, followed by bioinformatics analysis, revealed that many novel transcripts are over-expressed in either larvae- or post-larvae-stage prawn, shedding light on the molecular basis underlying M. rosenbergii metamorphosis. Fast larval molting rates and periodic morphological changes were reflected in over-expression of transcripts annotated to the cell cycle, DNA replication and morphogenic pathways (i.e., Hedgehog and Wnt). Further characterization of transcripts assigned to morphogenic pathways by real-time RT-PCR reconfirmed their over-expression in larvae, albeit with a more complex expression pattern when examined in the individual developmental stages. The expression level of an orthologue of cytochrome P450, 15A1, known to epoxidize methyl farnesoate in insects, was increased in the late larval and early post-larval stages, in accordance with the role of methyl farnesoate in crustacean metamorphosis. This study exemplifies the applicability of a high-throughput sequencing approach for studying complex traits, including metamorphosis, providing new insight into this unexplored area of crustacean research. PMID:23372848

Ventura, Tomer; Manor, Rivka; Aflalo, Eliahu D; Chalifa-Caspi, Vered; Weil, Simy; Sharabi, Omri; Sagi, Amir

2013-01-01

415

Transcription factor E93 specifies adult metamorphosis in hemimetabolous and holometabolous insects  

PubMed Central

All immature animals undergo remarkable morphological and physiological changes to become mature adults. In winged insects, metamorphic changes either are limited to a few tissues (hemimetaboly) or involve a complete reorganization of most tissues and organs (holometaboly). Despite the differences, the genetic switch between immature and adult forms in both types of insects relies on the disappearance of the antimetamorphic juvenile hormone (JH) and the transcription factors Krüppel-homolog 1 (Kr-h1) and Broad-Complex (BR-C) during the last juvenile instar. Here, we show that the transcription factor E93 is the key determinant that promotes adult metamorphosis in both hemimetabolous and holometabolous insects, thus acting as the universal adult specifier. In the hemimetabolous insect Blattella germanica, BgE93 is highly expressed in metamorphic tissues, and RNA interference (RNAi)-mediated knockdown of BgE93 in the nymphal stage prevented the nymphal–adult transition, inducing endless reiteration of nymphal development, even in the absence of JH. We also find that BgE93 down-regulated BgKr-h1 and BgBR-C expression during the last nymphal instar of B. germanica, a key step necessary for proper adult differentiation. This essential role of E93 is conserved in holometabolous insects as TcE93 RNAi in Tribolium castaneum prevented pupal–adult transition and produced a supernumerary second pupa. In this beetle, TcE93 also represses expression of TcKr-h1 and TcBR-C during the pupal stage. Similar results were obtained in the more derived holometabolous insect Drosophila melanogaster, suggesting that winged insects use the same regulatory mechanism to promote adult metamorphosis. This study provides an important insight into the understanding of the molecular basis of adult metamorphosis. PMID:24778249

Ureña, Enric; Manjón, Cristina; Franch-Marro, Xavier; Martín, David

2014-01-01

416

Evaluation of the genotoxic and teratogenic potential of a municipal sludge and sludge-amended soil using the amphibian Xenopus laevis and the tobacco: Nicotiana tabacum L. var. xanthi Dulieu  

Microsoft Academic Search

The toxic, genotoxic and teratogenic potential of a municipal sewage sludge was assessed using the micronucleus assay on the larvae of the amphibian Xenopus laevis and with the tobacco somatic mutation test using the yellow–green xanthi Dulieu mutant a1+\\/a1a2+\\/a2. The teratogenic potential was assessed by means of the Frog Embryo Teratogenesis Assay-Xenopus (FETAX). Various doses of the pasty sludge added

Pascale Chenon; Laury Gauthier; Pascale Loubières; Alain Séverac; Marcel Delpoux

2003-01-01

417

Analysis of gene expression in Homarus americanus larvae exposed to sublethal concentrations of endosulfan during metamorphosis.  

PubMed

Agricultural pesticide runoff has been suspected as the cause of numerous fish kills in rivers throughout Prince Edward Island but the impact on the surrounding marine environment is unknown. Endosulfan, an organochlorine pesticide, is a potent neurotoxin and molt inhibitor used to combat the Colorado potato beetle however it has the potential to affect non-target organisms including the American lobster (Homarus americanus). Metamorphosis is a critical stage of development and the effects of contaminant exposure during this time are largely unknown in lobster. A 14day endosulfan exposure was performed to identify the effects on survival, development and gene expression in lobster larvae during metamorphosis; all of which were predicted to be negatively impacted. The higher endosulfan concentrations resulted in greater mortality and a significant increase in the number of days required to reach metamorphosis in surviving animals. A custom made H. americanus microarray was used for monitoring the changes in expression of 14,592 genes at the termination of the exposure. Genes with >1.5 fold change and identified as being significant at p<0.05 using one-way ANOVA were selected for further analysis. A total of 707 genes were identified as being significantly differentiated, however with only ~40% annotation of the array, the majority of these genes were unknown. Annotated genes of interest were involved in many processes: development, metabolism, immunity and oxidative stress response and gene regulation. Nine genes of interest (histone H1, farnesoic acid O-methyltransferase, cuticle protein, glutathione S-transferase, thioredoxin, NADH dehydrogenase, ecdysone nuclear receptor Fushi tarazu F1 (FTZ-F1), ferritin and ecdysone inducible protein E75 (EIP-E75)) were selected for RT-qPCR validation of the microarray results. The RT-qPCR method was more sensitive than the microarray yet detected similar expression patterns. The two highest endosulfan concentrations resulted in increased mortalities, developmental delays in reaching metamorphosis and significant changes in gene expression. This research provides a foundation for using microarray gene expression profiles as screening tools for exploring the impact of environmental contaminants on lobster. PMID:24041715

Bauer, Megan; Greenwood, Spencer J; Clark, K Fraser; Jackman, Paula; Fairchild, Wayne

2013-12-01

418

14 CFR 29.519 - Hull type rotorcraft: Water-based and amphibian.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Hull type rotorcraft: Water-based and amphibian. 29.519 Section 29.519 Aeronautics and Space ...Loads § 29.519 Hull type rotorcraft: Water-based and amphibian. (a) General. For hull type...

2010-01-01

419

14 CFR 29.519 - Hull type rotorcraft: Water-based and amphibian.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 false Hull type rotorcraft: Water-based and amphibian. 29.519 Section 29.519 Aeronautics and Space ...Loads § 29.519 Hull type rotorcraft: Water-based and amphibian. (a) General. For hull type...

2014-01-01

420

14 CFR 29.519 - Hull type rotorcraft: Water-based and amphibian.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Hull type rotorcraft: Water-based and amphibian. 29.519 Section 29.519 Aeronautics and Space ...Loads § 29.519 Hull type rotorcraft: Water-based and amphibian. (a) General. For hull type...

2013-01-01

421

14 CFR 29.519 - Hull type rotorcraft: Water-based and amphibian.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Hull type rotorcraft: Water-based and amphibian. 29.519 Section 29.519 Aeronautics and Space ...Loads § 29.519 Hull type rotorcraft: Water-based and amphibian. (a) General. For hull type...

2011-01-01

422

14 CFR 29.519 - Hull type rotorcraft: Water-based and amphibian.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Hull type rotorcraft: Water-based and amphibian. 29.519 Section 29.519 Aeronautics and Space ...Loads § 29.519 Hull type rotorcraft: Water-based and amphibian. (a) General. For hull type...

2012-01-01

423

Effects of an Infectious Fungus, Batrachochytrium dendrobatidis, on Amphibian Predator-Prey Interactions  

E-print Network

Effects of an Infectious Fungus, Batrachochytrium dendrobatidis, on Amphibian Predator examined the effects of an emerging fungal pathogen of amphibians, Batrachochytrium dendrobatidis, on anti BA, Searle CL, Blaustein AR (2011) Effects of an Infectious Fungus, Batrachochytrium dendrobatidis

Blaustein, Andrew R.

424

Neotropical Amphibian Declines Affect Stream Ecosystem Properties  

NASA Astrophysics Data System (ADS)

Global declines of amphibians are well documented, yet effects of these dramatic losses on ecosystem structure and function are poorly understood. As part of a larger collaborative project, we compared two upland Panamanian streams. Both streams are biologically and geologically similar; however, one stream (Fortuna) has recently experienced almost complete extirpation of stream-dwelling frogs, while the other (Cope) still has intact populations. We experimentally excluded tadpoles from localized areas in each stream. We then compared chlorophyll a, algal community composition, ash-free dry mass (AFDM), inorganic matter, and insect assemblages in control and exclusion areas. Additionally, we sampled the natural substrate of both streams monthly for chlorophyll a, algal community composition, AFDM, and inorganic matter. At Cope, chlorophyll a, AFDM, and inorganic matter were greater in areas where tadpoles were excluded than in their presence. Numbers of dominant algal species (e.g., Nupela praecipua and Eunotia siolii) were greater in the exclusion versus control treatments. Monthly sampling of natural substrate indicated higher chlorophyll a and AFDM at Cope compared to Fortuna. Our data suggest that stream-dwelling anuran larvae have significant impacts on algal communities. These results also have implications for predicting the relevance of short-term experimental manipulations to long-term, whole-stream processes.

Connelly, S.; Pringle, C. M.; Bixby, R. J.; Whiles, M. R.; Lips, K. R.; Brenes, R.; Colon-Gaud, J. C.; Kilham, S.; Hunte-Brown, M.

2005-05-01

425

Mechanics of blastopore closure during amphibian gastrulation.  

PubMed

Blastopore closure in the amphibian embryo involves large scale tissue reorganization driven by physical forces. These forces are tuned to generate sustained blastopore closure throughout the course of gastrulation. We describe the mechanics of blastopore closure at multiple scales and in different regions around the blastopore by characterizing large scale tissue deformations, cell level shape change and subcellular F-actin organization and by measuring tissue force production and structural stiffness of the blastopore during gastrulation. We find that the embryo generates a ramping magnitude of force until it reaches a peak force on the order of 0.5?N. During this time course, the embryo also stiffens 1.5 fold. Strain rate mapping of the dorsal, ventral and lateral epithelial cells proximal to the blastopore reveals changing patterns of strain rate throughout closure. Cells dorsal to the blastopore, which are fated to become neural plate ectoderm, are polarized and have straight boundaries. In contrast, cells lateral and ventral to the blastopore are less polarized and have tortuous cell boundaries. The F-actin network is organized differently in each region with the highest percentage of alignment occurring in the lateral region. Interestingly F-actin was consistently oriented toward the blastopore lip in dorsal and lateral cells, but oriented parallel to the lip in ventral regions. Cell shape and F-actin alignment analyses reveal different local mechanical environments in regions around the blastopore, which was reflected by the strain rate maps. PMID:25448691

Feroze, Rafey; Shawky, Joseph H; von Dassow, Michelangelo; Davidson, Lance A

2015-02-01

426

Amphibian populations in the terrestrial environment: Is there evidence of declines of terrestrial forest amphibians in northwestern California?  

USGS Publications Warehouse

Amphibian declines have been documented worldwide; however the vast majority are species associated with aquatic habitats. Information on the status and trends of terrestrial amphibians is almost entirely lacking. Here we use data collected across a 12-yr period (sampling from 1984-86 and from 1993-95) to address the question of whether evidence exists for declines among terrestrial amphibians in northwestern California forests. The majority of amphibians, both species and relative numbers, in these forests are direct-developing salamanders of the family Plethodontidae. We examined amphibian richness and evenness, and the relative abundances of the four most common species of plethodontid salamanders. We examined evidence of differences between years in two ecological provinces (coastal and interior) and across young, mature, and late seral forests and with reference to a moisture gradient from xeric to hydric within late seral forests. We found evidence of declines in species richness across years on late seral mesic stands and in the coastal ecological province, but these differences appeared to be caused by differences in the detection of rarer species, rather than evidence of an overall pattern. We also found differences among specific years in numbers of individuals of the most abundant species, Ensatina eschscholtzii, but these differences also failed to reflect a consistent pattern of declines between the two decadal sample periods. Results showing differences in richness, evenness, and relative abundances along both the seral and moisture continua were consistent with previous research. Overall, we found no compelling evidence of a downward trend in terrestrial plethodontid salamanders. We believe that continued monitoring of terrestrial salamander populations is important to understanding mechanisms of population declines in amphibian species. Copyright 2007 Society for the Study of Amphibians and Reptiles.

Welsh, H.H., Jr.; Fellers, G.M.; Lind, A.J.

2007-01-01

427

A review of the role of contaminants in amphibian declines  

USGS Publications Warehouse

CONCLUSIONS--Although there are no published studies that demonstrate beyond all doubt that contaminants are involved in long term population declines of amphibians, there is ample evidence and reason to encourage active research and concern about effects. Many contaminants are lethal to amphibians at environmentally realistic concentrations. Acute mortality from these compounds may be difficult to detect because investigators would have to be present shortly after exposures. Chronic mortality may be masked by metapopulation phenomena so that areas that serve as population sinks may be repeatedly recolonized and difficult to identify. Metapopulation dynamics also make it more difficult to define discrete populations. Contaminants also have many sublethal effects on behavior, energetics, malformations, and diverse effects on physiological pathways which, by themselves might not lead to overt death but could alter reproduction or interact with other factors to result in gradual declines in populations. Scientific understanding of these interactions, and of the ecotoxicology of amphibians in general is far behind what is known about birds, fish, and mammals, and research is desperately needed in this area. Some specific suggestions for critically needed research include: (1) Determination of lethal concentrations of common contaminants - pesticides, PAHs, metals--under environmentally realistic conditions of light, temperature, and water chemistry. (2) Better understanding of the effects of long term (weeks, months), low- concentration exposure of persistent pesticides and stable contaminants on amphibians. (3) Development and refinement of bioindicators in amphibians to use in monitoring and screening for potential effects of contaminants in declining amphibian populations. (4) Further studies on the interaction between contaminants and disease agents including immunosuppression in amphibians. (5) Additional research on the interaction between ultraviolet radiation - both UV-A and UV-B--and a broader range of contaminants. (6) Development of models to assess risk in amphibians as related to landscape factors and especially in the aquatic-terrestrial interface. (7) Population survival requires that organisms survive through their entire life cycle; to date, there have been no studies that have examined the responses of amphibians to contaminants in all phases (egg, embryo, larvae and adult) of their life cycles.

Sparling, D.W.

2003-01-01

428

Proteomic response of marine invertebrate larvae to ocean acidification and hypoxia during metamorphosis and calcification.  

PubMed

Calcifying marine invertebrates with complex life cycles are particularly at risk to climate changes as they undergo an abrupt ontogenetic shift during larval metamorphosis. Although our understanding of the larval response to climate changes is rapidly advancing, the proteome plasticity involved in a compensatory response to climate change is still unknown. In this study, we investigated the proteomic response of metamorphosing larvae of the tubeworm Hydroides elegans, challenged with two climate change stressors, ocean acidification (OA; pH 7.6) and hypoxia (HYP; 2.8 mg O2 l(-1)), and with both combined. Using a two-dimensional gel electrophoresis (2-DE)-based approach coupled with mass spectrometry, we found that climate change stressors did not affect metamorphosis except under OA, but altered the larval proteome and phosphorylation status. Metabolism and various stress and calcification-related proteins were downregulated in response to OA. In OA and HYP combined, HYP restored the expression of the calcification-related proteins to the control levels. We speculate that mild HYP stress could compensate for the negative effects of OA. This study also discusses the potential functions of selected proteins that might play important roles in larval acclimation and adaption to climate change. PMID:24307710

Mukherjee, Joy; Wong, Kelvin K W; Chandramouli, Kondethimmanahalli H; Qian, Pei-Yuan; Leung, Priscilla T Y; Wu, Rudolf S S; Thiyagarajan, Vengatesen

2013-12-15

429

A new clarification method to visualize biliary degeneration during liver metamorphosis in Sea Lamprey (Petromyzon marinus).  

PubMed

Biliary atresia is a rare disease of infancy, with an estimated 1 in 15,000 frequency in the southeast United States, but more common in East Asian countries, with a reported frequency of 1 in 5,000 in Taiwan. Although much is known about the management of biliary atresia, its pathogenesis is still elusive. The sea lamprey (Petromyzon marinus) provides a unique opportunity to examine the mechanism and progression of biliary degeneration. Sea lamprey develop through three distinct life stages: larval, parasitic, and adult. During the transition from larvae to parasitic juvenile, sea lamprey undergo metamorphosis with dramatic reorganization and remodeling in external morphology and internal organs. In the liver, the entire biliary system is lost, including the gall bladder and the biliary tree. A newly-developed method called "CLARITY" was modified to clarify the entire liver and the junction with the intestine in metamorphic sea lamprey. The process of biliary degeneration was visualized and discerned during sea lamprey metamorphosis by using laser scanning confocal microscopy. This method provides a powerful tool to study biliary atresia in a unique animal model. PMID:24962075

Chung-Davidson, Yu-Wen; Davidson, Peter J; Scott, Anne M; Walaszczyk, Erin J; Brant, Cory O; Buchinger, Tyler; Johnson, Nicholas S; Li, Weiming

2014-01-01

430

A new clarification method to visualize biliary degeneration during liver metamorphosis in sea lamprey (Petromyzon marinus)  

USGS Publications Warehouse

Biliary atresia is a rare disease of infancy, with an estimated 1 in 15,000 frequency in the southeast United States, but more common in East Asian countries, with a reported frequency of 1 in 5,000 in Taiwan. Although much is known about the management of biliary atresia, its pathogenesis is still elusive. The sea lamprey (Petromyzon marinus) provides a unique opportunity to examine the mechanism and progression of biliary degeneration. Sea lamprey develop through three distinct life stages: larval, parasitic, and adult. During the transition from larvae to parasitic juvenile, sea lamprey undergo metamorphosis with dramatic reorganization and remodeling in external morphology and internal organs. In the liver, the entire biliary system is lost, including the gall bladder and the biliary tree. A newly-developed method called “CLARITY” was modified to clarify the entire liver and the junction with the intestine in metamorphic sea lamprey. The process of biliary degeneration was visualized and discerned during sea lamprey metamorphosis by using laser scanning confocal microscopy. This method provides a powerful tool to study biliary atresia in a unique animal model.

Chung-Davidson, Yu-Wen; Davidson, Peter J.; Scott, Anne M.; Walaszczyk, Erin J.; Brant, Cory O.; Buchinger, Tyler; Johnson, Nicholas S.; Li, Weiming

2014-01-01

431

INFLUENCE OF LAND USE ON POSTMETAMORPHIC BODY SIZE OF PLAYA LAKE AMPHIBIANS  

Microsoft Academic Search

Abstract: Agricultural land use may indirectly affect the body size of amphibians by altering the hydroperiods,of nearby wetlands and influencing amphibian,densities—both factors which can limit the larval and postmetamorphic,growth rates of amphibians. Wemeasured postmetamorphic body size for 4 species (Spea multiplicata, S. bombifrons, Bufo cogna- tus, Ambystoma tigrinum mavortium) and 3 age classes (metamorph, subadult, adult) of amphibians captured at

MATTHEW J. GRAY; LOREN M. SMITH

2005-01-01

432

Amphibian cathelicidin fills the evolutionary gap of cathelicidin in vertebrate.  

PubMed

Cathelicidins comprise a family of antimicrobial peptides (AMPs) sharing a highly conserved cathelin domain, and play a central role in the innate defense against infection in most of vertebrates. But so far it has not yet been found in amphibians although a large number of other groups of AMPs have been identified. In the current work, the first amphibian cathelicidin (cathelicidin-AL) has been characterized from the frog skin of Amolops loloensis. Cathelicidin-AL (RRSRRGRGGGRRGGSGGRGGRGGGGRSGAGSSIAGVGSRGGGGGRHYA) is a cationic peptide containing 48 amino acid residues (aa) with 12 basic aa and no acidic aa. The chemical synthesized peptide efficiently killed bacteria and some fungal species including clinically isolated drug-resistance microorganisms. The cDNA encoding cathelicidin-AL precursor was cloned from the skin cDNA library of A. loloensis. As other cathelicidins, the precursor of cathelicidin-AL also contains highly conserved anionic cathelin domain of cysteine proteinase inhibitor followed by the AMP fragment at C-terminus. Phylogenetic analysis revealed that as connecting link, the amphibian cathelicidin predates reptilia but postdates fish cathelicidin. The peptide purification combined with gene cloning results confirms the presence of cathelicidin in amphibians and filled the evolutionary gap of cathelicidin in vertebrate, considering amphibians' special niche as the animals bridging the evolutionary land-water gap. PMID:22009138

Hao, Xue; Yang, Hailong; Wei, Ling; Yang, Shilong; Zhu, Wenjuan; Ma, Dongying; Yu, Haining; Lai, Ren

2012-08-01

433

The cause of global amphibian declines: a developmental endocrinologist's perspective  

PubMed Central

Greater than 70% of the world's amphibian species are in decline. We propose that there is probably not a single cause for global amphibian declines and present a three-tiered hierarchical approach that addresses interactions among and between ultimate and proximate factors that contribute to amphibian declines. There are two immediate (proximate) causes of amphibian declines: death and decreased recruitment (reproductive failure). Although much attention has focused on death, few studies have addressed factors that contribute to declines as a result of failed recruitment. Further, a great deal of attention has focused on the role of pathogens in inducing diseases that cause death, but we suggest that pathogen success is profoundly affected by four other ultimate factors: atmospheric change, environmental pollutants, habitat modification and invasive species. Environmental pollutants arise as likely important factors in amphibian declines because they have realized potential to affect recruitment. Further, many studies have documented immunosuppressive effects of pesticides, suggesting a role for environmental contaminants in increased pathogen virulence and disease rates. Increased attention to recruitment and ultimate factors that interact with pathogens is important in addressing this global crisis. PMID:20190117

Hayes, T. B.; Falso, P.; Gallipeau, S.; Stice, M.

2010-01-01

434

Mitogenomic perspectives on the origin and phylogeny of living amphibians.  

PubMed

Establishing the relationships among modern amphibians (lissamphibians) and their ancient relatives is necessary for our understanding of early tetrapod evolution. However, the phylogeny is still intractable because of the highly specialized anatomy and poor fossil record of lissamphibians. Paleobiologists are still not sure whether lissamphibians are monophyletic or polyphyletic, and which ancient group (temnospondyls or lepospondyls) is most closely related to them. In an attempt to address these problems, eight mitochondrial genomes of living amphibians were determined and compared with previously published amphibian sequences. A comprehensive molecular phylogenetic analysis of nucleotide sequences yields a highly resolved tree congruent with the traditional hypotheses (Batrachia). By using a molecular clock-independent approach for inferring dating information from molecular phylogenies, we present here the first molecular timescale for lissamphibian evolution, which suggests that lissamphibians first emerged about 330 million years ago. By observing the fit between molecular and fossil times, we suggest that the temnospondyl-origin hypothesis for lissamphibians is more credible than other hypotheses. Moreover, under this timescale, the potential geographic origins of the main living amphibian groups are discussed: (i) advanced frogs (neobatrachians) may possess an Africa-India origin; (ii) salamanders may have originated in east Asia; (iii) the tropic forest of the Triassic Pangaea may be the place of origin for the ancient caecilians. An accurate phylogeny with divergence times can be also helpful to direct the search for "missing" fossils, and can benefit comparative studies of amphibian evolution. PMID:16012106

Zhang, Peng; Zhou, Hui; Chen, Yue-Qin; Liu, Yi-Fei; Qu, Liang-Hu

2005-06-01

435

A multilocus timescale for the origin of extant amphibians.  

PubMed

One of the most hotly debated topics in vertebrate evolution is the origin of extant amphibians (Lissamphibia). The recent contribution of molecular data is shedding new light on this debate, but many important questions still remain unresolved. I have assembled a large and comprehensive multilocus dataset (the largest to date in terms of number and heterogeneity of sequence characters) combining mitogenomic and nuclear information from 23 genes for a sufficiently dense taxon sampling with the key major lineages of extant amphibians. This dataset has been used to infer a robust phylogenetic framework and molecular timescale for the origin of extant amphibians employing the most recent phylogenetic and dating methods, as well as several alternative calibration schemes. The monophyly of each extant amphibian order and the sister group relationship between frogs and salamanders (Batrachia hypothesis) are all strongly supported. Dating analyses (all methods and calibration schemes used) suggest that the origin of extant amphibians (divergence between caecilian and batrachians) occurred in the Late Carboniferous, around 315 Mya, and the divergence between frogs and salamanders occurred in the Early Permian, around 290 Mya. These age estimates are more consistent with the fossil record than previous older estimates, and more in line with the Temnospondyli or the Lepospondyli hypotheses of lissamphibian ancestry (although the polyphyly hypothesis cannot be completely ruled out). PMID:20399871

San Mauro, Diego

2010-08-01

436

Estimating terrestrial amphibian pesticide body burden through dermal exposure.  

PubMed

Dermal exposure presents a potentially significant but understudied route for pesticide uptake in terrestrial amphibians. Our study measured dermal uptake of pesticides of varying hydrophobicity (logKow) in frogs. Amphibians were indirectly exposed to one of five pesticide active ingredients through contact with contaminated soil: imidacloprid (logKow = 0.57), atrazine (logKow = 2.5), triadimefon (logKow = 3.0), fipronil (logKow = 4.11) or pendimethalin (logKow = 5.18). All amphibians had measurable body burdens at the end of the exposure in concentrations ranging from 0.019 to 14.562 ?g/g across the pesticides tested. Atrazine produced the greatest body burdens and bioconcentration factors, but fipronil was more permeable to amphibian skin when application rate was considered. Soil partition coefficient and water solubility were much better predictors of pesticide body burden, bioconcentration factor, and skin permeability than logKow. Dermal uptake data can be used to improve risk estimates of pesticide exposure among amphibians as non-target organisms. PMID:25063914

Van Meter, Robin J; Glinski, Donna A; Hong, Tao; Cyterski, Mike; Henderson, W Matthew; Purucker, S Thomas

2014-10-01

437

Influence of agricultural landscape structure on a Southern High Plains, USA, amphibian assemblage  

Microsoft Academic Search

Landscape structure can influence demographics of spatially structured populations, particularly less vagile organisms such as amphibians. We examined the influence of agricultural landscape structure on community composition and relative abundance of the 4 most common amphibians in the Southern High Plains of central USA. Amphibian populations were monitored using pitfall traps and drift fence at 16 playa wetlands (8 playas\\/year)

Matthew J. Gray; Loren M. Smith; Raquel I. Leyva

2004-01-01

438

Effects of forest removal on amphibian migrations: implications for habitat and landscape connectivity  

Microsoft Academic Search

Summary 1. Habitat loss is a leading cause of global amphibian declines. Forest removal is a particularly significant threat because an estimated 82% of amphibians rely on forests for part of their lives. 2. Biphasic amphibians rely on suitable terrestrial habitat to support their post-metamorphic growth and survival and also to maintain appropriate habitat and landscape connectivity. 3. We created

Brian D. Todd; Thomas M. Luhring; Betsie B. Rothermel; J. Whitfield Gibbons

2009-01-01

439

Patterns of amphibian and reptile diversity at Berara Forest (Sahamalaza Peninsula), NW Madagascar  

Microsoft Academic Search

Amphibians and reptiles were surveyed at Berara, a forest on the Sahamalaza Peninsula, NW Madagascar. Visual methods and pitfalls were used, leading to the discovery of 12 amphibian and 30 reptile species. The herpetofaunal community appeared as a mosaic of dry forest species and species from the more humid Sambirano Domain. The comparatively low amphibian diversity may be correlated with

Franco Andreone; Miguel Vences; Jasmin Emile Randrianirina

2001-01-01

440

Cognitive and Emotional Evaluation of an Amphibian Conservation Program for Elementary School Students  

Microsoft Academic Search

The authors describe a study aimed at enhancing knowledge about amphibian species. Two classes of 3rd and 4th graders aged 9-11 years participated in the study. In addition, approximately one half of the students participated in an environmental conservation action designated to preserve migrating amphibians. During this action, students encountered living amphibians. Students who participated in the conservation action performed

Christoph Randler; Angelika Ilg; Janina Kern

2005-01-01

441

Dryness increases predation risk in efts: support for an amphibian decline hypothesis  

Microsoft Academic Search

One hypothesis for amphibian declines is that increased dryness attributed to global climate change exposes amphibians to greater biotic threat and, consequently, greater mortality. But, little is known about behavioral responses of terrestrial amphibians to dry conditions alone or in combination with biotic threats. We used field observations and laboratory experiments to test the response of efts (terrestrial juveniles) of

Jason R. Rohr; Dale M. Madison

2003-01-01

442

Qualitative risk analysis of introducing Batrachochytrium dendrobatidis to the UK through the importation of live amphibians.  

PubMed

The international amphibian trade is implicated in the emergence and spread of the amphibian fungal disease chytridiomycosis, which has resulted in amphibian declines and extinctions globally. The establishment of the causal pathogen, Batrachochytrium dendrobatidis (Bd), in the UK could negatively affect the survival of native amphibian populations. In recognition of the ongoing threat that it poses to amphibians, Bd was recently included in the World Organisation for Animal Health Aquatic Animal Health Code, and therefore is in the list of international notifiable diseases. Using standardised risk analysis guidelines, we investigated the likelihood that Bd would be introduced to and become established in wild amphibians in the UK through the importation of live amphibians. We obtained data on the volume and origin of the amphibian trade entering the UK and detected Bd infection in amphibians being imported for the pet and private collection trade and also in amphibians already held in captive pet, laboratory and zoological collections. We found that current systems for recording amphibian trade into the UK underestimate the volume of non-European Union trade by almost 10-fold. We identified high likelihoods of entry, establishment and spread of Bd in the UK and the resulting major overall impact. Despite uncertainties, we determined that the overall risk estimation for the introduction of Bd to the UK through the importation of live amphibians is high and that risk management measures are required, whilst ensuring that negative effects on legal trade are minimised. PMID:22436458

Peel, Alison J; Hartley, Matt; Cunningham, Andrew A

2012-03-20

443

Use of multiple dispersal pathways facilitates amphibian persistence in stream networks  

E-print Network

Use of multiple dispersal pathways facilitates amphibian persistence in stream networks Evan H. Campbell Granta,b,1 , James D. Nicholsa , Winsor H. Lowec , and William F. Fagand a Northeast Amphibian) Although populations of amphibians are declining worldwide, there is no evidence that salamanders occupying

Lowe, Winsor H.

444

Climatic change and wetland desiccation cause amphibian decline in Yellowstone National Park  

E-print Network

Climatic change and wetland desiccation cause amphibian decline in Yellowstone National Park Sarah) Amphibians are a bellwether for environmental degradation, even in natural ecosystems such as Yellowstone severe declines in 4 once-common amphibian species native to Yellowstone. Climate monitoring over 6

Hadly, Elizabeth

445

Low Prevalence of Chytrid Fungus (Batrachochytrium dendrobatidis) in Amphibians of U.S. Headwater Streams  

E-print Network

Low Prevalence of Chytrid Fungus (Batrachochytrium dendrobatidis) in Amphibians of U.S. Headwater of amphibian populations have been associated with chytridiomycosis, a disease caused by the aquatic fungus amphibians globally, most surveys in North America have focused primarily on wetland-associated species

Lowe, Winsor H.

446

50 CFR 16.14 - Importation of live amphibians or their eggs.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Importation of live amphibians or their eggs. 16.14 Section...Wildlife § 16.14 Importation of live amphibians or their eggs. Upon the filing...under § 14.61, all species of live amphibians or their eggs may be imported,...

2012-10-01

447

Biodiversity and Conservation 2, 290-303 (1993) Global amphibian declines: a perspective from  

E-print Network

Biodiversity and Conservation 2, 290-303 (1993) Global amphibian declines: a perspective from the possibility of a global decline in amphibians prompted this assessment of the West Indian species. At the species level, the West Indian amphibian fauna (156 species. all frogs and toads) has not undergone

Hedges, Blair

448

Functional Coupling Between Substantia Nigra and Basal Ganglia Homologues in Amphibians  

E-print Network

Functional Coupling Between Substantia Nigra and Basal Ganglia Homologues in Amphibians Kim L. Hoke the existence of a homologue of the mam- malian substantia nigra­basal ganglia circuit in the amphibian brain proposed that homologous basal ganglia circuits may exist in both amphibians and mammals (reviewed

Ryan, Michael J.

449

50 CFR 16.14 - Importation of live amphibians or their eggs.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Importation of live amphibians or their eggs. 16.14 Section...Wildlife § 16.14 Importation of live amphibians or their eggs. Upon the filing...under § 14.61, all species of live amphibians or their eggs may be imported,...

2013-10-01

450

1098 volume 119 | number 8 | August 2011 Environmental Health Perspectives Amphibians are arguably the "poster child"  

E-print Network

1098 volume 119 | number 8 | August 2011 · Environmental Health Perspectives Research Amphibians pollution is a concern for the health of both amphibians and humans. It is consid ered the second greatest of amphibians, such as endocrine and immune systems, are simi lar to those in humans (Hayes 2005), and a genome

Rohr, Jason

451

Modelling the future distribution of the amphibian chytrid fungus: the influence of climate and  

E-print Network

FORUM Modelling the future distribution of the amphibian chytrid fungus: the influence of climate of amphibians are believed to be caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Hence of this pathogen and curtail the amphibian biodiversity crisis. 2. In this issue of Journal of Applied Ecology

Rohr, Jason

452

Abundance and species composition of amphibians, small mammals, and songbirds in  

E-print Network

Abundance and species composition of amphibians, small mammals, and songbirds in riparian forest trapped anuran amphibians and small mammals and spot-mapped bird territories around 12 lakes (4 treatment levels, 3 replicates) before and after harvesting. Changes in small mammal or amphibian abundance were

Macdonald, Ellen

453

Effects of habitat loss and fragmentation on amphibians: A review and prospectus  

E-print Network

Effects of habitat loss and fragmentation on amphibians: A review and prospectus Samuel A. Cushman Amphibians Dispersal Persistence Extinction Review A B S T R A C T Habitat loss and fragmentation are among the largest threats to amphibian populations. However, most studies have not provided clear insights

454

Climate change and outbreaks of amphibian chytridiomycosis in a montane area  

E-print Network

Climate change and outbreaks of amphibian chytridiomycosis in a montane area of Central Spain College Faculty of Medicine, St Mary's Campus, Norfolk Place, London W2 1PG, UK Amphibian species by the chytridiomycete fungus, Batrachochytrium dendrobatidis. This disease of amphibians has recently emerged within

Carrascal, Luis M.

455

Energy, water and large-scale patterns of reptile and amphibian species richness in Europe  

E-print Network

Energy, water and large-scale patterns of reptile and amphibian species richness in Europe Miguel Á and amphibian species richness in Europe and 11 environmental variables related to five hypotheses in log elevation explaining an additional 6%. For amphibians, annual actual evapotranspiration (AET

Rodríguez, Miguel Ángel

456

Tadpole Mouthpart Depigmentation as an Accurate Indicator of Chytridiomycosis, an Emerging Disease of Amphibians  

E-print Network

of Amphibians ROLAND A. KNAPP AND JESS A. T. MORGAN Chytridiomycosis is an emerging infectious disease of amphibians caused by the fungal pathogen Batrachochytrium dendrobatidis, and its role in causing population. CHYTRIDIOMYCOSIS is an emerging infec- tious disease of amphibians caused by Batrachochytrium dendrobatidis

Knapp, Roland

457

Amphibian Populations in Farmed and CREP Wetlands in the Des Moines Lobe in Central Iowa  

E-print Network

Amphibian Populations in Farmed and CREP Wetlands in the Des Moines Lobe in Central Iowa Principal if native amphibian species (e.g. boreal chorus frogs, northern leopard frogs, American toads) are present declines in amphibian communities throughout the U.S. The loss in numbers and diminished distribution

Koford, Rolf R.

458

Emerging infectious disease and the loss of biodiversity in a Neotropical amphibian community  

E-print Network

Emerging infectious disease and the loss of biodiversity in a Neotropical amphibian community Karen the rapid appearance of a pathogenic chytrid fungus Batrachochytrium den- drobatidis in an amphibian community at El Cope´, Panama, and subsequent mass mortality and loss of amphibian biodiversity across eight

Horton, Tom

459

Where have all the tadpoles gone? Individual genetic tracking of amphibian larvae until adulthood  

E-print Network

Where have all the tadpoles gone? Individual genetic tracking of amphibian larvae until adulthood is a challenge that has hampered studies on recruitment, dispersal, migration and survivorship of amphibians been previously used in amphibians to follow individuals across different life cycle stages. Here, we

Ringler, Eva

460

INFLUENCE OF LAND USE ON POSTMETAMORPHIC BODY SIZE OF PLAYA LAKE AMPHIBIANS  

E-print Network

INFLUENCE OF LAND USE ON POSTMETAMORPHIC BODY SIZE OF PLAYA LAKE AMPHIBIANS MATTHEW J. GRAY,1, 2 79409, USA Abstract: Agricultural land use may indirectly affect the body size of amphibians by altering the hydroperiods of nearby wetlands and influencing amphibian densities--both factors which can limit the larval

Gray, Matthew

461

50 CFR 16.14 - Importation of live amphibians or their eggs.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Importation of live amphibians or their eggs. 16.14 Section...Wildlife § 16.14 Importation of live amphibians or their eggs. Upon the filing...under § 14.61, all species of live amphibians or their eggs may be imported,...

2011-10-01

462

EN-005 Wildlife March 2001 Response of Amphibians to Partial Cutting in a  

E-print Network

EN-005 Wildlife March 2001 Response of Amphibians to Partial Cutting in a Coastal Mixed-Conifer Forest: Management Practices for Retaining Amphibian Habitat in the Vancouver Forest Region By Linda A. Dupuis and F. Louise Waterhouse KEYWORDS: forestry, land management, habitat management, amphibians

463

Is forest close to lakes ecologically unique? Analysis of vegetation, small mammals, amphibians, and songbirds  

E-print Network

Is forest close to lakes ecologically unique? Analysis of vegetation, small mammals, amphibians. Two species of anuran amphibians [wood frog (Rana sylvatica) and boreal toad (Bufo boreas boreas and sites up to 100 m into the lakeside forest were small. Use of upland habitats by amphibians (juvenile

Macdonald, Ellen

464

FrogLog Vol. 100 | January 2012 | 1 www.amphibians.org  

E-print Network

FrogLog Vol. 100 | January 2012 | 1 www.amphibians.org South America Regional Focus INSIDE News Amphibian Specialist Group (ASG) announces the fifth annual award to recognize individuals who have made a significant contribution to promoting the conservation of globally threatened amphibians. The award of US$25

Funk, W. Chris

465

Remarkable Amphibian Biomass and Abundance in an Isolated Wetland: Implications for Wetland  

E-print Network

Remarkable Amphibian Biomass and Abundance in an Isolated Wetland: Implications for Wetland, Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154­4004, U.S.A. §Partners in Amphibian and Reptile: Despite the continuing loss of wetland habitats and associated declines in amphibian populations, attempts

Georgia, University of

466

Complexity in conservation: lessons from the global decline of amphibian populations  

E-print Network

REVIEW Complexity in conservation: lessons from the global decline of amphibian populations Andrew@bcc.orst.edu Abstract As part of an overall ``biodiversity crisis'' many amphibian populations are in decline throughout, and the introduction of non-native species. In this paper, we argue that amphibian population declines are caused

Blaustein, Andrew R.

467

50 CFR 16.14 - Importation of live amphibians or their eggs.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 false Importation of live amphibians or their eggs. 16.14 Section...Wildlife § 16.14 Importation of live amphibians or their eggs. Upon the filing...under § 14.61, all species of live amphibians or their eggs may be imported,...

2014-10-01

468

Will climate change reduce the efficacy of protected areas for amphibian conservation in Italy?  

E-print Network

Will climate change reduce the efficacy of protected areas for amphibian conservation in Italy s t r a c t Amphibians are an important and imperiled component of biodiversity. In this study we analyze the effi- cacy of Italian reserve network for protecting multiple amphibian species in a climate

Zimmermann, Niklaus E.

469

11 . Alternative reproductive tactics In amphibians KELLY R . ZAMUDIO AND LAURE  

E-print Network

11 . Alternative reproductive tactics In amphibians KELLY R . ZAMUDIO AND LAURE CHAPTER SUMMARY Frogs and salamanders, the two most diverse lin~agcs of amphibians, differ significantly in reproductive of alternative reproductive tactics. However, OUf understanding of the evolution of amphibian alternative

Zamudio, Kelly R.

470

The effects of multiple stressors on wetland communities: pesticides, pathogens and competing amphibians  

E-print Network

amphibians JULIA C. BUCK*, ERIN A. SCHEESSELE*, RICK A. RELYEA AND ANDREW R. BLAUSTEIN* *Zoology Department described as the sixth mass extinction, and amphibians are among the most affected groups. The causes of global amphibian population declines and extinctions are varied, complex and context-dependent and may

Blaustein, Andrew R.

471

Evolutionary dynamics of frequency-dependent growth strategy in cannibalistic amphibians  

E-print Network

Evolutionary dynamics of frequency-dependent growth strategy in cannibalistic amphibians J Hiranocho, Otsu, Shiga 520-2113, Japan ABSTRACT Cannibalistic amphibian larval morphs, which have greater, 4: 719­736 © 2002 J.Y. Wakano #12;In amphibians, cannibalism is common during the period from

Wakano, Joe Yuichiro

472

AMPHIBIANS AND REPTILES OF THE GREAT FALLS BYPASSED REACHES IN SOUTH CAROLINA  

E-print Network

AMPHIBIANS AND REPTILES OF THE GREAT FALLS BYPASSED REACHES IN SOUTH CAROLINA MICHAEL E. DORCAS of the amphibians and reptiles inhabiting the Great Falls Bypassed Reaches of the Catawba River in South Carolina. A list of 85 species of amphibians and reptiles potentially occurring in the Great Falls Bypassed Reaches

Dorcas, Michael E.

473

Canyon of the Ancients National Monument Amphibian and Reptile Brad Lambert  

E-print Network

Canyon of the Ancients National Monument Amphibian and Reptile Inventory by Brad Lambert March 2004 .................................................................................................. 14 AMPHIBIANS OBSERVED IN 2003 SURVEYS: SEE APPENDIX A FOR INDIVIDUAL SPECIES MAPS Program to conduct field surveys for amphibians and reptiles in the Canyon of the Ancients National

474

50 CFR 16.14 - Importation of live amphibians or their eggs.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Importation of live amphibians or their eggs. 16.14 Section...Wildlife § 16.14 Importation of live amphibians or their eggs. Upon the filing...under § 14.61, all species of live amphibians or their eggs may be imported,...

2010-10-01

475

An overview of the evolution and conservation of West Indian amphibians and reptiles  

E-print Network

An overview of the evolution and conservation of West Indian amphibians and reptiles S. Blair.15% of Earth's land area, but the region supports 3.0% (180 species) of the world's amphibians and 6.3% (520 status of only the amphibians has been assessed comprehensively, and 84% of those species are considered

Hedges, Blair

476

Climate warming and the decline of amphibians and reptiles in Europe  

E-print Network

SPECIAL ISSUE Climate warming and the decline of amphibians and reptiles in Europe M. B. Arau´jo1 the relationship between current European distributions of amphibian and reptile species and observed climate ask, first, what proportion of amphibian and reptile species are projected to lose and gain suitable

Binford, Michael W.

477

First Evidence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Hong  

E-print Network

First Evidence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Hong Kong Amphibian Trade Jonathan E. Kolby1,2 *, Kristine M. Smith2 , Lee Berger1 , William B. Karesh2 of America, 3 Amphibian Disease Laboratory, Institute for Conservation Research, San Diego Zoo Global, San

Gray, Matthew

478

Amphibian antimicrobial peptides and Protozoa: Lessons from parasites Luis Rivas a,  

E-print Network

Review Amphibian antimicrobial peptides and Protozoa: Lessons from parasites Luis Rivas a, , Juan peptides (AMPs) from amphibians and other eukaryotes recognize pathogenicity patterns mostly related or leishmaniasis. Herein we review the scarce but growing body of knowledge addressing the use of amphibian AMPs

Pompeu Fabra, Universitat

479

DNA barcoding applied to ex situ tropical amphibian conservation programme reveals cryptic diversity in captive  

E-print Network

DNA barcoding applied to ex situ tropical amphibian conservation programme reveals cryptic, Universidad de los Andes, A.A. 4976, Bogota, Colombia, 4 El Valle Amphibian Conservation Center, El Valle de Department of Conservation and Science, Houston Zoo, Houston, TX 77030, USA Abstract Amphibians constitute

Crawford, Andrew J.

480

Epidemic disease decimates amphibian abundance, species diversity, and evolutionary history in the  

E-print Network

Epidemic disease decimates amphibian abundance, species diversity, and evolutionary history, and approved June 22, 2010 (received for review December 7, 2009) Amphibian populations around the world.Despitetheseverityofthecrisis,quantitative analyses of the effects of the epidemic on amphibian abundance and diversity have been unavailable

Crawford, Andrew J.