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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

Apoptosis in amphibian organs during metamorphosis  

Microsoft Academic Search

During amphibian metamorphosis, the larval tissues\\/organs rapidly degenerate to adapt from the aquatic to the terrestrial\\u000a life. At the cellular level, a large quantity of apoptosis occurs in a spatiotemporally-regulated fashion in different organs\\u000a to ensure timely removal of larval organs\\/tissues and the development of adult ones for the survival of the individuals. Thus,\\u000a amphibian metamorphosis provides us a good

Atsuko Ishizuya-Oka; Takashi Hasebe; Yun-Bo Shi

2010-01-01

6

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

7

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

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

Do effects of mercury in larval amphibians persist after metamorphosis?  

PubMed

Despite widespread concern about 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 ecotoxicology focus on larval life stages. Studies that focus solely on early life stages may miss important effects of contaminant exposure, such as latent effects that manifest some time after previous exposure. Moreover, it is often assumed that effects observed in amphibian larvae will persist to affect survival or reproduction later in life. We used terrestrial enclosures to determine whether exposure to mercury (Hg) through maternal transfer and/or larval diet had any adverse effects in post-metamorphic American toads (Bufo americanus). We found a 5% difference in size at metamorphosis that was attributed to maternal Hg exposure persisted for 1 year in the terrestrial environment, resulting in a 7% difference at the conclusion of the study. Although patterns of survival differed among treatments through time, we found no overall difference in survival after 1 year. We also found no evidence of emergent latent effects in the terrestrial toads that could be attributed to earlier exposure. Our results indicate that adverse effects of maternal Hg exposure that were observed in larval amphibians may persist to affect later terrestrial life stages but that no novel adverse effects developed when animals were raised in a semi-natural environment. Moreover, we found no evidence of persistent effects of dietary Hg exposure in larvae, highlighting a need for greater focus on maternal effects in amphibian ecotoxicology. Finally, we suggest an increase in the use of longitudinal studies to better understand contaminant impacts to amphibian populations via effects in both aquatic and terrestrial life stages. PMID:21850489

Todd, Brian D; Willson, John D; Bergeron, Christine M; Hopkins, William A

2012-01-01

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

Involvement of Glucocorticoids in the Reorganization of the Amphibian Immune System at Metamorphosis  

PubMed Central

In recent years, integrative animal biologists and behavioral scientists have begun to understand the complex interactions between the immune system and the neuroendocrine system. Amphibian metamorphosis offers a unique opportunity to study dramatic hormone-driven changes in the immune system in a compressed time frame. In the South African clawed frog, Xenopus laevis, the larval pattern of immunity is distinct from that of the adult, and metamorphosis marks the transition from one pattern to the other. Climax of metamorphosis is characterized by significant elevations in thyroid hormones, glucocorticoid hormones, and the pituitary hormones, prolactin and growth hormone. Previously, we and others have shown that elevated levels of unbound glucocorticoid hormones found at climax of metamorphosis are associated with a natural decline in lymphocyte numbers, lymphocyte viability, and mitogen-induced proliferation. Here we present evidence that the mechanism for loss of lymphocytes at metamorphosis is glucocorticoid-induced apoptosis. Inhibition of lymphocyte function and loss of lymphocytes in the thymus and spleen are reversible by in vitro or in vivo treatment with the glucocorticoid receptor antagonist, RU486, whereas the mineralocorticoid receptor antagonist, RU26752, is poorly effective. These observations support the hypothesis that loss of larval lymphocytes and changes in lymphocyte function are due to elevated concentrations of glucocorticoids that remove unnecessary lymphocytes to allow for development of immunological tolerance to the new adult-specific antigens that appear as a result of metamorphosis. PMID:9587715

Barker, Katherine S.; Davis, A. Tray

1997-01-01

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

Amphibian lipid levels at metamorphosis correlate to post-metamorphic terrestrial survival  

Microsoft Academic Search

In organisms that have complex life cycles, factors in the larval environment may affect both larval and adult traits. For\\u000a amphibians, the postmetamorphic transition from the aquatic environment to terrestrial habitat may be a period of high juvenile\\u000a mortality. We hypothesized that lipid stores at metamorphosis may affect an animal’s success during this critical transition\\u000a period. We examined variation in

David E. Scott; Erin D. Casey; Michele F. Donovan; Tracy K. Lynch

2007-01-01

18

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

19

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...

20

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.

2012-06-26

21

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

22

The molecular basis of thyroid hormone-dependent central nervous system remodeling during amphibian metamorphosis 1 Presented at the Symposium ‘Comparative Neuroendocrinology of Vertebrate Reproduction and Growth: Organismal, Cellular and Molecular Aspects’ held at the Annual Meeting of the Society for Experimental Biology (SEB), University of Kent, Canterbury, 7–11 April, 1997. 1  

Microsoft Academic Search

Tadpole metamorphosis involves a coordinated series of changes in virtually every tissue of the body. This developmental process is induced by the single morphogen, thyroid hormone (TH). The amphibian central nervous system (CNS) is a primary target for TH, and it undergoes dramatic morphological and cytoarchitectural changes in response to the hormone. TH acts by regulating gene expression and its

Robert J. Denver

1998-01-01

23

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

24

Metamorphosis-related changes in leukocyte profiles of larval bullfrogs ( Rana catesbeiana )  

Microsoft Academic Search

Metamorphosis in amphibians is a fascinating phenomenon that offers physiologists a number of opportunities to study aspects\\u000a of tissue growth and lysis in animals. In larval amphibians, tissues are formed early on during larval growth, then are vastly\\u000a reorganized and broken down during metamorphosis, and the effects of this phenomenon on the relative distribution of white\\u000a blood cells in circulation

Andrew K. Davis

2009-01-01

25

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...

26

Anuran metamorphosis: A model for gravitational study on motor development  

Microsoft Academic Search

Limbs and supporting structures of an organism experience a full weight of its own when it lands from water, because neutral buoyancy in the aquatic habitat will be no longer available in the terrestrial world. Metamorphosis of anuran amphibians presents a good research model to examine how this transition from non?loading to weight?loading affects development of motor capacity at the

Jae Seung Shin; Jin Cheul Park; Masamichi Yamashita

2000-01-01

27

Thyroid Hormone Receptor Genes of Neotenic Amphibians  

Microsoft Academic Search

.   Since thyroid hormones play a pivotal role in amphibian metamorphosis we used PCR to amplify DNA fragments corresponding\\u000a to a portion of the ligand-binding domain of the thyroid hormone receptor (TR) genes in several neotenic amphibians: the obligatory\\u000a neotenic members of the family Proteidea the mudpuppy Necturus maculosus and Proteus anguinus as well as two members of the facultative

Rachid Safi; Agnès Begue; Catherine Hänni; Dominique Stehelin; Jamshed R. Tata; Vincent Laudet

1997-01-01

28

Amphibia-Reptilia 34 (2013): 151-162 A non-invasive water-borne hormone assay for amphibians  

E-print Network

and field populations of amphibians and the effects of urbanization, pesticides and diseases. An important - U.S. Fish and Wildlife Service, San Marcos Aquatic Resources Center, 500 East McCarty Lane, San

Gabor, Caitlin - Department of Biology, Texas State University

2013-01-01

29

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, ...

30

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

31

EFFECTS OF AN INSECTICIDE ON AMPHIBIANS IN LARGE-SCALE EXPERIMENTAL PONDS  

Microsoft Academic Search

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

Michelle D. Boone; Raymond D. Semlitsch; James F. Fairchild; Betsie B. Rothermel

2004-01-01

32

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......

33

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.

2012-12-20

34

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.

2013-09-14

35

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...

36

Thyroid hormone deiodinase type 2 mRNA levels in sea lamprey (Petromyzon marinus) are regulated during metamorphosis and in response to a thyroid challenge.  

PubMed

Thyroid hormones (THs) are crucial for normal vertebrate development and are the one obligate morphogen that drives amphibian metamorphosis. However, contrary to other metamorphosing vertebrates, lampreys exhibit a sharp drop in serum TH early in metamorphosis, and anti-thyroid agents such as potassium perchlorate (KClO(4)) induce metamorphosis. The type 2 deiodinase (D2) enzyme is a key regulator of TH availability during amphibian metamorphosis. We set out to determine how D2 may be involved in the regulation of lamprey metamorphosis and thyroid homeostasis. We cloned a 1.8Kb Petromyzon marinus D2 cDNA that includes the entire protein coding region and a selenocysteine (Sec) codon. Northern blotting indicated that the lamprey D2 mRNA is the longest reported to date (>9Kb). Using real-time PCR, we showed that intestinal and hepatic D2 mRNA levels were elevated prior to and during the early stages of metamorphosis and then declined dramatically to low levels that were sustained for the remainder of metamorphosis. These data are consistent with previously reported changes in serum TH levels and deiodinase activity. Treatment of larvae with either TH or KClO(4) significantly affected D2 mRNA levels in the intestine and liver. These D2 mRNA levels during metamorphosis and in response to thyroid challenges suggest that D2 may function in the regulation of TH levels during lamprey metamorphosis and the maintenance of TH homeostasis. PMID:23295540

Stilborn, S Salina M; Manzon, Lori A; Schauenberg, Jennifer D; Manzon, Richard G

2013-03-01

37

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

38

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

39

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

40

Overwintered Bullfrog tadpoles negatively affect Salamanders and Anurans in native amphibian communities  

USGS Publications Warehouse

We examined the interactive effects of overwintered Bullfrog (Rana catesbeiana) tadpoles and pond hydroperiod on a community of larval amphibians in outdoor mesocosms including American Toads (Bufo americanus), Southern Leopard Frogs (Rana sphenocephala), and Spotted Salamanders (Ambystoma maculatum) - species within the native range of Bullfrogs. Spotted Salamanders and Southern Leopard Frogs were negatively influenced by the presence of overwintered Bullfrogs. Spotted Salamanders had shorter larval periods and slightly smaller masses at metamorphosis, and Southern Leopard Frogs had smaller masses at metamorphosis when reared with Bullfrogs than without. Presence of overwintered Bullfrogs, however, did not significantly affect American Toads. Longer pond hydroperiods resulted in greater survival, greater size at metamorphosis, longer larval periods, and later time until emergence of the first metamorphs for Southern Leopard Frog tadpoles and Spotted Salamander larvae. Our study demonstrated that overwintered Bullfrog tadpoles can respond to changing pond hydroperiods and can negatively impact metamorphosis of native amphibians.

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

2004-01-01

41

Thyroid hormone receptors in perennibranchiate amphibians.  

PubMed

Thyroid hormone has long been known to induce metamorphosis in amphibians. The understanding of the molecular steps controlling the completion of metamorphosis has nevertheless been hampered by the complexity of this event. The comparison of organisms in which metamorphosis does or does not occur, may provide clues into the molecular cascade that control it. Up to now the available data suggest that perennibranchiate amphibians retain their larval characters mainly because their tissues do not respond to thyroid hormones. In such a context the recent identification of a thyroid hormone receptor alpha in the perennibranchiate Proteus anguinus is provocative (Ho Huynh et al., Int. J. Dev. Biol. 40:537-543, 1996). In the present paper, we provide evidences that this recently described sequence is in fact a sequence from Xenopus laevis. Indeed, we identified the authentic thyroid hormone receptors of both alpha and beta types in two perennibranchiate species Necturus maculosus and Proteus anguinus. The various controls required to ascertain the authenticity of a developmental gene cloned by PCR or RT-PCR analysis are presented. The results reported in the present paper are relevant with phylogenetical analysis. This induces our team to conclude that the Proteus TR alpha sequence reported by Ho Huynh et al. (1996) reflects a contamination of the RT-PCR by Xenopus laevis material. PMID:9240572

Safi, R; Deprez, A; Laudet, V

1997-06-01

42

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

43

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

44

Architecture and metamorphosis.  

PubMed

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. These 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 humans. The human MSC consists of nine aaRSs (LysRS, ArgRS, GlnRS, AspRS, MetRS, IleRS, LeuRS, GluProRS, and bifunctional aaRs) and three scaffold proteins (AIMP1/p43, AIMP2/p38, and AIMP3/p18), and has a molecular weight of 1.5 million Dalton. The MSC has been proposed to have a functional dualism: 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

Guo, Min; Yang, Xiang-Lei

2014-01-01

45

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

46

Evaluation of gene expression endpoints in the context of a Xenopus laevis metamorphosis-based bioassay to detect thyroid hormone disruptors  

Microsoft Academic Search

Thyroid hormones (TH) are important in growth, development and the maintenance of proper cellular metabolism in vertebrates. Amphibian metamorphosis is completely dependent on TH and forms the basis of a screen for thyroid axis disrupting chemicals that currently relies on external morphological endpoints and changes in thyroid gland histology. The requirement for TH-dependent gene expression makes it possible to augment

Fang Zhang; Sigmund J. Degitz; Gary W. Holcombe; Patricia A. Kosian; Joseph Tietge; Nik Veldhoen; Caren C. Helbing

2006-01-01

47

ACY: February 22, 2005 Metamorphosis  

E-print Network

in complete metamorphosis: egg, larva, pupa, adult. 6. Students will be able to name the stages in incomplete. Students will be able to state that the cocoon is a covering which surrounds the pupa in butterflies: caterpillar (alive) large enough to be handled blowfly pupae fruit flies developing in Petri dishes blowfly

Ginzel, Matthew

48

Feature-based image metamorphosis  

Microsoft Academic Search

A new technique is presented for the metamorphosis of one digital image into another. The approach gives the animator high-level control of the visual effect by providing natural feature-based specification and interaction. When used effectively, this technique can give the illusion that the photographed or computer generated subjects are transforming in a fluid, surrealistic, and often dramatic way. Comparisons with

Thaddeus Beier; Shawn Neely

1992-01-01

49

Thyroid hormone receptor genes of neotenic amphibians.  

PubMed

Since thyroid hormones play a pivotal role in amphibian metamorphosis we used PCR to amplify DNA fragments corresponding to a portion of the ligand-binding domain of the thyroid hormone receptor (TR) genes in several neotenic amphibians: the obligatory neotenic members of the family Proteidea the mudpuppy Necturus maculosus and Proteus anguinus as well as two members of the facultative neotenic Ambystoma genus: the axolotl Ambystoma mexicanum and the tiger salamander Ambystoma tigrinum. In addition, we looked for TR genes in the genome of an apode Typhlonectes compressicaudus. TR genes were found in all these species including the obligatory neotenic ones. The PCR fragments obtained encompass both the C and E domains and correspond to alpha and beta genes. Their sequences appear to be normal, suggesting that there is no acceleration of evolutionary rates in the TR genes of neotenic amphibians. This result is not surprising for Ambystomatidae, which are known to respond to T3 (3,3',5-triiodothyronine) but is not in agreement with biochemical and biological data showing that Proteidea cannot respond to thyroid hormones. Interestingly, by RT-PCR analysis we observed a high expression levels of TRalpha in gills, intestine, and muscles of Necturus as well as in the liver of Ambystoma mexicanum, whereas TRbeta expression was only detected in Ambystoma mexicanum but not in Necturus. Such a differential expression pattern of TRalpha and TRbeta may explain the neoteny in Proteidea. The cloning of thyroid-hormone-receptor gene fragments from these species will allow the molecular study of their failure to undergo metamorphosis. PMID:9169551

Safi, R; Begue, A; Hänni, C; Stehelin, D; Tata, J R; Laudet, V

1997-06-01

50

Anuran metamorphosis: a model for gravitational study on motor development.  

PubMed

Limbs and supporting structures of an organism experience a full weight of its own when it lands from water, because neutral buoyancy in the aquatic habitat will be no longer available in the terrestrial world. Metamorphosis of anuran amphibians presents a good research model to examine how this transition from non-loading to weight-loading affects development of motor capacity at the time of their first emergence on land. Our video analysis of the transitional anurans, Rana catesbeiana, at Gosner stage 46 (the stage of complete transformation) demonstrated that the take-off speed increased 1.23-fold after the first six hours of weight-loading on the wet ground. It did not increase further during the following three days of loading, and was close to the level of mature frogs with different body mass. During development of larvae in deep water with no chance of landing through metamorphosis, both tension and power of a hindlimb anti-gravity muscle increased 5-fold between stages 37 and 46. However, the muscle contractility increased more rapidly when the larvae could access the wet ground by their natural landing behavior after stages 41-42. Muscle power, one of major factors affecting locomotory speed, was 1.29-fold greater in the loaded than in the non-loaded larvae at the transitional stage. Thus, weight-loading had a potentially significant effect on the elevation of motor capacity, with a similar extent of increment in locomotory speed and muscle power during the last stages of metamorphosis. Such a motor adjustment of the froglets in a relatively short transitional period would be important for effective ecological interactions and survival in their inexperienced terrestrial life. PMID:12760373

Shin, J S; Park, J C; Yamashita, M; Choi, I H

2000-09-01

51

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

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

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

54

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

55

Amphibian chytridiomycosis in Luxembourg  

Microsoft Academic Search

Aquatic-phase amphibians at eight sites in Luxembourg were tested for the fungus Batrachochytrium dendrobatidis, which causes a disease responsible for population declines among many amphibian species worldwide. Infected amphibians were found at two of the sites tested; two further sites also showed marginally positive results. The ecology of B. den- drobatidis and the necessity for biosecurity protocol implementation by fieldworkers

Laura R. Wood; Richard A. Griffiths; Laurent Schley; R. A. Griffiths

2009-01-01

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  

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

58

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

59

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

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

1997-01-01

61

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

62

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

63

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

64

Distortion of frontal bones results from cell apoptosis by the mechanical force from the up-migrating eye during metamorphosis in Paralichthys olivaceus.  

PubMed

Craniofacial remodeling during flatfish metamorphosis, including eye migration, is perhaps the most striking example of asymmetric postembryonic development in the vertebrate world. The asymmetry of the cranium mainly results from distortion of the frontal bones, which depends on eye migration during metamorphosis. However, it is unclear how the up-migrating eye causes distortion of the frontal bones. In this study, we first show that distortion of the frontal bones during metamorphosis in Paralichthys olivaceus is the result of cell apoptosis, rather than cell autophagy or cell proliferation. Secondly, we report that cell apoptosis in the frontal bones is induced by the mechanical force transferred from the up-migrating eye. The mechanical force from the up-migrating eye signals through FAK to downstream molecules that are integrated into the BMP-2 signal pathway. Finally, it is shown that cell apoptosis in the frontal bones is activated by the intrinsic mitochondrial pathway; the extrinsic death receptor is not involved in this process. Moreover, cell apoptosis in frontal bones is not induced directly by thyroid hormones, which are thought to mediate metamorphosis in flatfishes and directly mediate cell apoptosis during amphibian metamorphosis. These findings help identify the major signaling route used during regulation of frontal bone distortion during metamorphosis in flatfish, and indicate that the asymmetry of the cranium, or at least the distortion of frontal bones, is the result of rather than the reason underlying eye migration. PMID:25622577

Sun, Mingyan; Wei, Fen; Li, Hui; Xu, Juan; Chen, Xinye; Gong, Xiaoling; Tian, Yongsheng; Chen, Songlin; Bao, Baolong

2015-05-01

65

An endogenous peptide is involved in internal control of metamorphosis in the marine invertebrate Cassiopea xamachana (Cnidaria: Scyphozoa).  

PubMed

In the metagenetic life-cycle of the scyphozoan Cassiopea xamachana metamorphosis of planula-larvae or larva-like buds to polyps is triggered by specific external cues which are transmitted inside the larva or bud where internal signals finally coordinate the initiation of metamorphosis. This study deals with an endogenous metamorphosis inducer present in planulae and buds of Cassiopea. The inductive cue is localized in the basal part of the buds and can be characterized as a peptide with an apparent molecular weight of about 7,000 Da. Further purification was performed via reversed phase HPLC on a C18 column. Additional inhibitor assays revealed that protein kinase C and PI3 kinase, two known elements of the metamorphosis-inducing signal transduction cascade in Cassiopea, may act downstream of the endogenous inducing peptide. PMID:12632179

Thieme, C; Hofmann, D K

2003-03-01

66

The gastropod nervous system in metamorphosis.  

PubMed

Many gastropods, including the sea hare Aplysia californica, undergo metamorphosis in passing from the larval to the juvenile phases of their life cycle. During metamorphosis, the gastropod nervous system is affected by both progressive and regressive neuronal events. In addition to this metamorphic reorganization, the nervous system appears to be centrally involved in initiating metamorphosis. We propose that gastropods not only possess temporally distinct neuronal adaptations for the specific needs of the larval and juvenile phases, but also another transient neuronal adaptation specialized to subserve the metamorphic episode. PMID:2258721

Marois, R; Carew, T J

1990-10-01

67

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

68

Metamorphosis  

ERIC Educational Resources Information Center

One thing history's torrent appears to be sweeping away is, ironically, the study of its most productive wellspring, Western civilization. "The Vanishing West", a report the National Association of Scholars released in May 2011, documents the extent of this vanishing. The traditional Western civilization survey requirement, commonplace only…

Balch, Stephen H.

2012-01-01

69

[Hormonal determination of the differentiation of striated skeletal muscle in urodele amphibians].  

PubMed

In the urodelan amphibian Pleurodeles waltlii, spontaneous external metamorphosis was correlated with an increase in the serum level of thyroxine (T4). Within the same period, a change occurred in the myofibrillar ATPase profile of the dorsal skeletal muscle; fibres of larval type were gradually replaced by transitional fibres (type IIC), then by adult fibres of the types I, IIA, and IIB. Likewise, a myosin isoenzymic transition was observed. In larval animals, myosin electrophoresis revealed 3 bands corresponding with isoforms having identical heavy chains (MHC), but different light chains (MLC). In the course of metamorphosis, the 3 larval isomyosins were replaced by 3 isoforms having the adult type MHC and different motility. In a related neotenic species, Ambystoma mexicanum, no spontaneous anatomic metamorphosis occurred; at the time it should theoretically take place, the serum T4 level remained low. The ATPase profile was modified, but transitional fibres that replaced the initial larval types appeared to be persistent, and adult fiber types appeared only in a small amount. Myosin isoenzymic transition was also incomplete, larval isoforms were still distinguished in the neotenic adults. Similar persistence of larval characters was observed in adult Proteus anguinus, a perennibranch that never undergoes anatomical metamorphosis. Experimental hypothyroidian Pleurodeles waltlii displayed no external metamorphosis, only the larval fibre types and isomyosins were detected in those animals. External metamorphosis was induced in Ambystoma mexicanum by a triiodothyronine treatment. A complete myosin isoenzymic transition was observed in metamorphosed animals. These results tend to indicate that a moderate increase in the level of thyroid hormones is sufficient to determine the production of the adult type MHC molecules and the differentiation of the corresponding myofibrillar types in the skeletal dorsal muscle of amphibians, while a marked increase would be necessary for repressing the initial larval feature. PMID:2973102

Chanoine, C; Janmot, C; Guyot-Lenfant, M; Durand, J P; d'Albis, A; Gallien, C L

1988-01-01

70

IMMUNOLOGICAL STUDIES OF INSECT METAMORPHOSIS  

PubMed Central

1. In the pupal stage of the cecropia silkworm, antigen 7, a protein with the solubility characteristics of an albumin, is present in female blood in approximately a thousand times higher concentration than in the blood of males. Antigen 7 is undetectable in the blood of larvae of either sex. It first appears in the blood after the larva has spun its cocoon, and is present throughout all subsequent stages of metamorphosis. Late in the pupal-adult transformation, when the eggs are produced, the concentration of antigen 7 in female blood decreases significantly. 2. An antigen which could not be distinguished from antigen 7 immunologically is present in solution in the yolk of unfertilized eggs. 3. In females which, by ovariectomy, were prevented from forming eggs, the concentration of antigen 7 in the blood increased during the usual period of egg formation rather than undergoing the normal decrease. Ovaries transferred to the hemocoel of males produced eggs but were unable to incorporate antigen 7 in the yolk unless a detectable amount of the protein was present in the blood. The ovaries of polyphemus females which had been transfused with cecropia blood incorporated cecropia antigen 7 into the eggs they produced. These lines of evidence indicate that antigen 7 is secreted into the blood by some tissue other than the ovaries, and that it is subsequently drawn from the blood and deposited in the yolk. 4. The concentration of antigen 7 in the clear, liquid fraction of the yolk is four times higher than the maximum concentration attained in the blood during metamorphosis, and twenty times higher than that of the blood at the conclusion of egg formation. The protein thus appears to be transferred from blood to yolk against a concentration gradient. PMID:13143187

Telfer, William H.

1954-01-01

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

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

73

The amphibian skin-associated microbiome across species, space and life history stages.  

PubMed

Skin-associated bacteria of amphibians are increasingly recognized for their role in defence against pathogens, yet we have little understanding of their basic ecology. Here, we use high-throughput 16S rRNA gene sequencing to examine the host and environmental influences on the skin microbiota of the cohabiting amphibian species Anaxyrus boreas, Pseudacris regilla, Taricha torosa and Lithobates catesbeianus from the Central Valley in California. We also studied populations of Rana cascadae over a large geographic range in the Klamath Mountain range of Northern California, and across developmental stages within a single site. Dominant bacterial phylotypes on amphibian skin included taxa from Bacteroidetes, Gammaproteobacteria, Alphaproteobacteria, Firmicutes, Sphingobacteria and Actinobacteria. Amphibian species identity was the strongest predictor of microbial community composition. Secondarily, within a given amphibian species, wetland site explained significant variation. Amphibian-associated microbiota differed systematically from microbial assemblages in their environments. Rana cascadae tadpoles have skin bacterial communities distinct from postmetamorphic conspecifics, indicating a strong developmental shift in the skin microbes following metamorphosis. Establishing patterns observed in the skin microbiota of wild amphibians and environmental factors that underlie them is necessary to understand skin symbiont community assembly, and ultimately, the role skin microbiota play in the extended host phenotype including disease resistance. PMID:24171949

Kueneman, Jordan G; Parfrey, Laura Wegener; Woodhams, Douglas C; Archer, Holly M; Knight, Rob; McKenzie, Valerie J

2014-03-01

74

Interaction between perchlorate and iodine in the metamorphosis of Hyla versicolor  

USGS Publications Warehouse

Perchlorate (ClO4-) is a water-soluble, inorganic anion that is often combined with ammonium, potassium or other cations for use in industry and agriculture. Ammonium perchlorate, for example, is a potent oxidizer and is used in various military applications including rocket fuel. It has also been found in an historically widely used fertilizer, Chilean nitrate and in other fertilizers. It has been found in ground and surface waters of over 30 states and is considered a human health risk. Because of its similar atomic radius and volume, perchlorate competes with iodide for thyroid uptake and storage and thereby inhibits production of thyroid hormones. Amphibians may be particularly affected by perchlorate because they rely on the thyroid for metamorphosis. This study exposed early larval Hyla versicolor to concentrations of perchlorate ranging from 2.2 to 50 ppm to determine the effects of perchlorate on a native amphibian. In addition, three controls, 0 perchlorate, 0 perchlorate with 0.10 ppm iodide (C + I) and 50 ppm perchlorate + 0.10 ppm iodide (50 + I) were tested. Mortality (< 11% with all treatments) and growth appeared to be unaffected by perchlorate. Inhibition of development started with 2.2 ppm perchlorate and little or no development occurred at 22.9 ppm and above. This inhibition was particularly apparent at the latter stages of development including hindlimb formation and metamorphosis. The estimated EC50 for total inhibition of metamorphosis at 70 days of treatment was 3.63 ppm. There was no evidence of inhibition of development with the 50 + I, C + I, or controls, indicating that the presence of small concentrations of iodide could counter the effects of perchlorate. When tadpoles that had been inhibited by perchlorate were subsequently treated with iodide, development through prometamorphosis progressed but mortality was very high.

Sparling, D.; Harvey, G.; Nzengung, V.

2003-01-01

75

Interaction between perchlorate and iodine in the metamorphosis of Hyla versicolor  

USGS Publications Warehouse

Perchlorate (ClO4-) is a water-soluble, inorganic anion that is often combined with ammonium, potassium or other cations for use in industry and agriculture. Ammonium perchlorate, for example, is a potent oxidizer and is used in various military applications including rocket fuel. It has also been found in an historically widely used fertilizer, Chilean nitrate and in other fertilizers. It has been found in ground and surface waters of over 30 states and is considered a human health risk. Because of its similar atomic radius and volume, perchlorate competes with iodide for thyroid uptake and storage and thereby inhibits production of thyroid hormones. Amphibians may be particularly affected by perchlorate because they rely on the thyroid for metamorphosis. This study exposed early larval Hyla versicolor to concentrations of perchlorate ranging from 2.2 to 50 ppm to determine the effects of perchlorate on a native amphibian. In addition, three controls, 0 perchlorate, 0 perchlorate with 0.10 ppm iodide (C + I) and 50 ppm perchlorate + 0.10 ppm iodide (50 + I) were tested. Mortality (<11% with all treatments) and growth appeared to be unaffected by perchlorate. Inhibition of development started with 2.2 ppm perchlorate and little or no development occurred at 22.9 ppm and above. This inhibition was particularly apparent at the latter stages of development including hindlimb formation and metamorphosis. The estimated EC50 for total inhibition of metamorphosis at 70 days of treatment was 3.63 ppm. There was no evidence of inhibition of development with the 50 + I, C + I, or controls, indicating that the presence of small concentrations of iodide could counter the effects of perchlorate. When tadpoles that had been inhibited by perchlorate were subsequently treated with iodide, development through prometamorphosis progressed but mortality was very high.

Sparling, D.W.; Harvey, G.; Nzengung, V.

2003-01-01

76

Amphibian Population Declines and Malformations  

E-print Network

1 Amphibian Population Declines and Malformations Matthew J. Gray University of Tennessee Hyla regilla, ORBufo periglenes, CR Extinct, 1989 Worldwide Amphibian Population Declines Global Amphibian of Amphibian Declines Prior 1970s: 1970-mid-1980s: Late 80s-Now: ·Few extinctions; some localized die-offs ·Few

Gray, Matthew

77

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

78

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

79

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.

80

Flatfish metamorphosis: A hypothalamic independent process?  

PubMed

Anuran and flatfish metamorphosis are tightly regulated by thyroid hormones that are the necessary and sufficient factors that drive this developmental event. In the present study whole mount in situ hybridization (WISH) and quantitative PCR in sole are used to explore the central regulation of flatfish metamorphosis. Central regulation of the thyroid in vertebrates is mediated by the hypothalamus-pituitary-thyroid (HPT) axis. Teleosts diverge from other vertebrates as hypothalamic regulation in the HPT axis is proposed to be through hypothalamic inhibition although the regulatory factor remains enigmatic. The dynamics of the HPT axis during sole metamorphosis revealed integration between the activity of the thyrotrophes in the pituitary and the thyroid follicles. No evidence was found supporting a role for thyroid releasing hormone (trh) or corticotrophin releasing hormone (crh) in hypothalamic control of TH production during sole metamorphosis. Intriguingly the results of the present study suggest that neither hypothalamic trh nor crh expression changes during sole metamorphosis and raises questions about the role of these factors and the hypothalamus in regulation of thyrotrophs. PMID:25575457

Campinho, Marco A; Silva, Nadia; Roman-Padilla, Javier; Ponce, Marian; Manchado, Manuel; Power, Deborah M

2015-03-15

81

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...

82

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

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.

84

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

85

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

86

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.

87

Amphibian declines: an immunological perspective Cynthia Careya,  

E-print Network

Amphibian declines: an immunological perspective Cynthia Careya, *, Nicholas Cohenb , Louise, amphibian populations have been declining on all six continents on which they live. Although habitat of amphibian declines, many amphibians are dying of infectious diseases in relatively pristine habitats

Gray, Matthew

88

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

89

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

USGS Publications Warehouse

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 ??g/L in P. regilla and 66.5 ??g/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 ??g/L for P. regilla and 0.55 ??g/L for R. boylii. All R. boylii exposed to concentrations of greater than 0.8 ??g/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. ?? 2009 SETAC.

Sparling, D.W.; Fellers, G.M.

2009-01-01

90

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

91

Organizational Metamorphosis in Space Research and Development.  

ERIC Educational Resources Information Center

The communicative, and therefore organizational and managerial, aspects of the Marshall Space Flight Center's (MSFC) metamorphosis from Saturn V to Skylab are analyzed. MSFC's consistent successes are attributed to the organization's commitment to communication systems, its technical integrity, and its single-minded purpose. (JMF)

Tompkins, Phillip K.

1978-01-01

92

HOLOMORPHIC EVOLUTION: METAMORPHOSIS OF THE LOEWNER EQUATION  

E-print Network

HOLOMORPHIC EVOLUTION: METAMORPHOSIS OF THE LOEWNER EQUATION FILIPPO BRACCI Contents 1 and the Loewner differential equation 7 3. Kufarev-Loewner chordal equation 8 4. Reversing evolution and SLE's 9 4 and S. D´iaz-Madrigal in [10], [11]. In this new framework, the accent is put on the evolution families

Bracci, Filippo

93

Structural Elements in Franz Kafka's "The Metamorphosis."  

ERIC Educational Resources Information Center

Notes that Kafka's "The Metamorphosis" is not only a masterpiece of modern literature but also a work that exemplifies many ideas of structural family therapy. Examines how Kafka's novella embodies concepts such as parentified children, enmeshment, intergenerational boundaries, coalitions and triangles, structural dysfunction, and structural…

Johnson, Scott

1993-01-01

94

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

95

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

96

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.

97

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

98

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

99

No evidence for dark energy metamorphosis?  

NASA Astrophysics Data System (ADS)

Recent attempts to fit type Ia supernova data by modelling the dark energy density as a truncated Taylor series have suggested the possibility of metamorphosis, i.e., a rapidly evolving equation of state parameter, wDE(z). However, we show that fits using that parametrization have significant problems. Evolution of wDE(z) is both favoured and in some sense forced, and the equation of state parameter blows up or diverges in large regions of the parameter space. To further elucidate these problems we have simulated sets of supernova data in a Lgr-universe to show that the suggested 'evidence' for metamorphosis is also common for wDE = -1.

Jönsson, J.; Goobar, A.; Amanullah, R.; Bergström, L.

2004-09-01

100

Skeletal metamorphosis in fibrodysplasia ossificans progressiva (FOP)  

Microsoft Academic Search

Metamorphosis, the transformation of one normal tissue or organ system into another, is a biological process rarely studied\\u000a in higher vertebrates or mammals, but exemplified pathologically by the extremely disabling autosomal dominant disorder fibrodysplasia\\u000a ossificans progressiva (FOP). The recurrent single nucleotide missense mutation in the gene encoding activin receptor IA\\/activin-like\\u000a kinase-2 (ACVR1\\/ALK2), a bone morphogenetic protein type I receptor that

Frederick S. Kaplan; Qi Shen; Vitali Lounev; Petra Seemann; Jay Groppe; Takenobu Katagiri; Robert J. Pignolo; Eileen M. Shore

2008-01-01

101

Molecular and Cellular Aspects of Amphibian Lens Regeneration  

PubMed Central

Lens regeneration among vertebrates is basically restricted to some amphibians. The most notable cases are the ones that occur in premetamorphic frogs and in adult newts. Frogs and newts regenerate their lens in very different ways. In frogs the lens is regenerated by transdifferentiation of the cornea and is limited only to a time before metamorphosis. On the other hand, regeneration in newts is mediated by transdifferentiation of the pigment epithelial cells of the dorsal iris and is possible in adult animals as well. Thus, the study of both systems could provide important information about the process. Molecular tools have been developed in frogs and recently also in newts. Thus, the process has been studied at the molecular and cellular levels. A synthesis describing both systems was long due. In this review we describe the process in both Xenopus and the newt. The known molecular mechanisms are described and compared. PMID:20638484

Henry, Jonathan J.; Tsonis, Panagiotis A.

2012-01-01

102

Metamorphosis in the Cirripede Crustacean Balanus amphitrite  

PubMed Central

Stalked and acorn barnacles (Cirripedia Thoracica) have a complex life cycle that includes a free-swimming nauplius larva, a cypris larva and a permanently attached sessile juvenile and adult barnacle. The barnacle cyprid is among the most highly specialized of marine invertebrate larvae and its settlement biology has been intensively studied. By contrast, surprisingly few papers have dealt with the critical series of metamorphic events from cementation of the cyprid to the substratum until the appearance of a suspension feeding juvenile. This metamorphosis is both ontogenetically complex and critical to the survival of the barnacle. Here we use video microscopy to present a timeline and description of morphological events from settled cyprid to juvenile barnacle in the model species Balanus amphitrite, representing an important step towards both a broader understanding of the settlement ecology of this species and a platform for studying the factors that control its metamorphosis. Metamorphosis in B. amphitrite involves a complex sequence of events: cementation, epidermis separation from the cypris cuticle, degeneration of cypris musculature, rotation of the thorax inside the mantle cavity, building of the juvenile musculature, contraction of antennular muscles, raising of the body, shedding of the cypris cuticle, shell plate and basis formation and, possibly, a further moult to become a suspension feeding barnacle. We compare these events with developmental information from other barnacle species and discuss them in the framework of barnacle settlement ecology. PMID:22666355

Maruzzo, Diego; Aldred, Nick; Clare, Anthony S.; Høeg, Jens T.

2012-01-01

103

Herpetological Review 43(1), 2012 78 AMPHIBIAN DISEASES  

E-print Network

of chytridiomycosis (Batrachochytri- um dendrobatidis) in amphibian samples using real-time Taqman PCR assay. Dis in Europe. Emerg. Infect. Dis. 11(10):1639­1641. hyaTT, a. d., d. g. BOyle, V. Olsen, d. B. BOyle, l. Berger

Gray, Matthew

104

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

105

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

106

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

107

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.

108

Metamorphosis of a Scleractinian Coral in Response to Microbial Biofilms  

PubMed Central

Microorganisms have been reported to induce settlement and metamorphosis in a wide range of marine invertebrate species. However, the primary cue reported for metamorphosis of coral larvae is calcareous coralline algae (CCA). Herein we report the community structure of developing coral reef biofilms and the potential role they play in triggering the metamorphosis of a scleractinian coral. Two-week-old biofilms induced metamorphosis in less than 10% of larvae, whereas metamorphosis increased significantly on older biofilms, with a maximum of 41% occurring on 8-week-old microbial films. There was a significant influence of depth in 4- and 8-week biofilms, with greater levels of metamorphosis occurring in response to shallow-water communities. Importantly, larvae were found to settle and metamorphose in response to microbial biofilms lacking CCA from both shallow and deep treatments, indicating that microorganisms not associated with CCA may play a significant role in coral metamorphosis. A polyphasic approach consisting of scanning electron microscopy, fluorescence in situ hybridization (FISH), and denaturing gradient gel electrophoresis (DGGE) revealed that coral reef biofilms were comprised of complex bacterial and microalgal communities which were distinct at each depth and time. Principal-component analysis of FISH data showed that the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Cytophaga-Flavobacterium of Bacteroidetes had the largest influence on overall community composition. A low abundance of Archaea was detected in almost all biofilms, providing the first report of Archaea associated with coral reef biofilms. No differences in the relative densities of each subdivision of Proteobacteria were observed between slides that induced larval metamorphosis and those that did not. Comparative cluster analysis of bacterial DGGE patterns also revealed that there were clear age and depth distinctions in biofilm community structure; however, no difference was detected in banding profiles between biofilms which induced larval metamorphosis and those where no metamorphosis occurred. This investigation demonstrates that complex microbial communities can induce coral metamorphosis in the absence of CCA. PMID:14766608

Webster, Nicole S.; Smith, Luke D.; Heyward, Andrew J.; Watts, Joy E. M.; Webb, Richard I.; Blackall, Linda L.; Negri, Andrew P.

2004-01-01

109

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...

110

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

111

The biology of coral metamorphosis: molecular responses of larvae to inducers of settlement and metamorphosis.  

PubMed

Like many other cnidarians, corals undergo metamorphosis from a motile planula larva to a sedentary polyp. In some sea anemones such as Nematostella this process is a smooth transition requiring no extrinsic stimuli, but in many corals it is more complex and is cue-driven. To better understand the molecular events underlying coral metamorphosis, competent larvae were treated with either a natural inducer of settlement (crustose coralline algae chips/extract) or LWamide, which bypasses the settlement phase and drives larvae directly into metamorphosis. Microarrays featuring >8000 Acropora unigenes were used to follow gene expression changes during the 12h period after these treatments, and the expression patterns of specific genes, selected on the basis of the array experiments, were investigated by in situ hybridization. Three patterns of expression were common-an aboral pattern restricted to the searching/settlement phase, a second phase of aboral expression corresponding to the beginning of the development of the calicoblastic ectoderm and continuing after metamorphosis, and a later orally-restricted pattern. PMID:21338599

Grasso, L C; Negri, A P; Fôret, S; Saint, R; Hayward, D C; Miller, D J; Ball, E E

2011-05-15

112

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

113

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

114

Time and size at metamorphosis related to adult fitness in Ambystoma talpoideum  

Microsoft Academic Search

The relationships among timing of metamorphosis, size at metamorphosis, and traits related to adult fitness were studied for 8 yr in the salamander Ambystoma talpoideum at a temporary pond. Among years, the modal time of metamorphosis and mean body size at metamorphosis were positively correlated with the date the pond dried. In years that the pond dried late, one group

R. D. Semlitsch; D. E. Scott; J. H. K. Pechmann

1988-01-01

115

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

116

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, Ôcanaries in a coal mineÕ, because, there has been no systematic evaluation of amphibian sensitivity to environmental challenges relative

Storfer, Andrew

117

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

118

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

119

Introduction Worldwide, amphibians today are experiencing the  

E-print Network

Introduction Worldwide, amphibians today are experiencing the greatest decline among all vertebrate worldwide of the rapid decline of amphibian populations (Lips et al., 2008). For amphibians, an effective@hotmail.com SS: sebastian.steinfartz@uni-bielefeld.de Abstract. In the face of the worldwide amphibian decline

Steinfartz, Sebastian

120

In Vitro organogenesis using amphibian pluripotent cells  

PubMed Central

Mesoderm induction as a result of the interaction between endoderm and ectoderm is one of the most crucial events in vertebrate development. We identified activin as a strong mesoderm-inducing factor in an animal cap assay, an in vitro assay system using amphibian pluripotential cell mass. Activin induces mesodermal tisswes including most dorsal mesodermal tissue, notochord (which has important roles in neural induction, somite segmentation, and endodermal organogenesis), and its effects are concentration-dependent. Animal cap cells treated with high concentrations of activin differentiate into anterior endoderm, which can act as an organizer, or center of body patterning. We have established an in vitro induction system for 22 different organs and tissues using animal cap cells, and have isolated many organ-specific genes. With these useful methods, and analysis of newly isolated tissue- and organ-specific genes, the molecular biological “road map” for organogenesis is being established.

Okabayashi, Koji; Asashima, Makoto

2006-01-01

121

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

122

Development of arginine vasotocin innervation in two species of anuran amphibian: Rana catesbeiana and Rana sylvatica.  

PubMed

Arginine vasotocin (AVT) is a neurotransmitter in the amphibian central nervous system and is released from the neurohypophysis in the regulation of hydromineral balance and other homeostatic functions. Many amphibians experience drastic changes in habitat with respect to water availability during their transformation from aquatic larvae to terrestrial adults. To examine whether metamorphosis is accompanied by a reorganization of central vasotocinergic neurons, the developmental organization of vasotocin neurons and nerve fibers was studied with immunocytochemistry in the brains of bullfrogs (Rana catesbeiana) and woodfrogs (R. sylvatica). In bullfrogs, early limb-bud-stage tadpoles had AVT-immunoreactive neurons and nerve fibers in the lateral septal nucleus, amygdala, preoptic hypothalamus, suprachiasmatic nucleus, and posterodorsal tegmentum. Woodfrog larvae showed similar patterns of hypothalamic AVT immunoreactivity, although neuronal staining in the amygdala did not appear until metamorphic climax, and never appeared in septal neurons or in the posterodorsal tegmentum. Whereas the highly terrestrial R. sylvatica adults must adapt to an adult habitat with prolonged periods of dehydration, R. catesbeiana adults remain semiaquatic and, as such, need not develop extreme mechanisms for water retention. Nonetheless, vasotocinergic pathways showed developmental similarities in the two species. The early appearance of AVT innervation in both Rana suggests that AVT has neuroregulatory functions well before metamorphosis. PMID:9072187

Mathieson, W B

1996-04-01

123

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

2015-02-01

124

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

E-print Network

, Duke University, Box 90338, Durham, NC 27708 Abstract: Population declines of amphibian species in many community of cutaneous flora may be important in explaining and preventing amphibian population declinesAmphibian Pathogen Batrachochytrium dendrobatidis Is Inhibited by the Cutaneous Bacteria

James, Timothy

125

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

126

The metamorphosis of the developing cerebellar microcircuit  

PubMed Central

The cerebellar cortical circuit with its organized and repetitive structure provides an excellent model system for studying how brain circuits are formed during development. The emergence of the mature brain requires that appropriate synaptic connections are formed and refined, which in the rodent cerebellum occurs primarily during the first three postnatal weeks. Developing circuits typically differ substantially from their mature counterparts, which suggests that development may not simply involve synaptic refinement, but rather involves restructuring of key synaptic components and network connections, in a manner reminiscent of metamorphosis. Here, we discuss recent evidence that, taken together, suggests that transient features of developing cerebellar synapses may act to coordinate network activity, and thereby shape the development of the cerebellar microcircuit. PMID:21353528

van Welie, Ingrid; Smith, Ikuko T; Watt, Alanna J

2011-01-01

127

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

128

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

129

Field Surveys of Amphibian Populations  

NSDL National Science Digital Library

Amphibian Research, a course offered at Saint Joseph's College in Rensselaer, Indiana, introduces freshmen- and sophomore-level biology and environmental science majors to investigative field research. Students learn to identify species and use standard f

Robert Brodman

2000-10-01

130

Thyroxine-Induced Metamorphosis in the Axolotl (Ambystoma mexicanum).  

PubMed

The axolotl (Ambystoma mexicanum) has remained an important model for regeneration and developmental biology for over a century. Although axolotls in captive-bred colonies usually exist in an aquatic form, they retain the ability to undergo metamorphosis following exposure to thyroid hormone. Here we present a robust method for inducing metamorphosis in adult axolotls that results in high survivability and produces terrestrial animals that can be maintained in long-term captivity. PMID:25740483

Coots, Peggy S; Seifert, Ashley W

2015-01-01

131

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

132

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

133

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 ...

134

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

135

North American amphibians: distribution and diversity  

USGS Publications Warehouse

Some 300 species of amphibians inhabit North America. The past two decades have seen an enormous growth in interest about amphibians and an increased intensity of scientific research into their fascinating biology and continent-wide distribution. This atlas presents the spectacular diversity of North American amphibians in a geographic context. It covers all formally recognized amphibian species found in the United States and Canada, many of which are endangered or threatened with extinction. Illustrated with maps and photos, the species accounts provide current information about distribution, habitat, and conservation. Researchers, professional herpetologists, and anyone intrigued by amphibians will value North American Amphibians as a guide and reference.

: Green, David M., (Edited By); Weir, Linda A.; Casper, Gary S.; Lannoo, Michael

2014-01-01

136

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

137

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.

138

Induction of Larval Metamorphosis of the Coral Acropora millepora by Tetrabromopyrrole Isolated from a Pseudoalteromonas Bacterium  

PubMed Central

The induction of larval attachment and metamorphosis of benthic marine invertebrates is widely considered to rely on habitat specific cues. While microbial biofilms on marine hard substrates have received considerable attention as specific signals for a wide and phylogenetically diverse array of marine invertebrates, the presumed chemical settlement signals produced by the bacteria have to date not been characterized. Here we isolated and fully characterized the first chemical signal from bacteria that induced larval metamorphosis of acroporid coral larvae (Acropora millepora). The metamorphic cue was identified as tetrabromopyrrole (TBP) in four bacterial Pseudoalteromonas strains among a culture library of 225 isolates obtained from the crustose coralline algae Neogoniolithon fosliei and Hydrolithon onkodes. Coral planulae transformed into fully developed polyps within 6 h, but only a small proportion of these polyps attached to the substratum. The biofilm cell density of the four bacterial strains had no influence on the ratio of attached vs. non-attached polyps. Larval bioassays with ethanolic extracts of the bacterial isolates, as well as synthetic TBP resulted in consistent responses of coral planulae to various doses of TBP. The lowest bacterial density of one of the Pseudoalteromonas strains which induced metamorphosis was 7,000 cells mm?2 in laboratory assays, which is on the order of 0.1 –1% of the total numbers of bacteria typically found on such surfaces. These results, in which an actual cue from bacteria has been characterized for the first time, contribute significantly towards understanding the complex process of acroporid coral larval settlement mediated through epibiotic microbial biofilms on crustose coralline algae. PMID:21559509

Tebben, Jan; Tapiolas, Dianne M.; Motti, Cherie A.; Abrego, David; Negri, Andrew P.; Blackall, Linda L.; Steinberg, Peter D.; Harder, Tilmann

2011-01-01

139

Understanding Amphibian Declines Through Geographic Approaches  

USGS Publications Warehouse

Growing concern over worldwide amphibian declines warrants serious examination. Amphibians are important to the proper functioning of ecosystems and provide many direct benefits to humans in the form of pest and disease control, pharmaceutical compounds, and even food. Amphibians have permeable skin and rely on both aquatic and terrestrial ecosystems during different seasons and stages of their lives. Their association with these ecosystems renders them likely to serve as sensitive indicators of environmental change. While much research on amphibian declines has centered on mysterious causes, or on causes that directly affect humans (global warming, chemical pollution, ultraviolet-B radiation), most declines are the result of habitat loss and habitat alteration. Improving our ability to characterize, model, and monitor the interactions between environmental variables and amphibian habitats is key to addressing amphibian conservation. In 2000, the U.S. Geological Survey (USGS) initiated the Amphibian Research and Monitoring Initiative (ARMI) to address issues surrounding amphibian declines.

Gallant, Alisa

2006-01-01

140

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.

141

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

142

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

143

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

144

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

145

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...

146

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.

147

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

148

Why Do We Need an Amphibian Ark?  

NSDL National Science Digital Library

The issue focused, peer reviewed article describes a response to the crisis of amphibian declines. The Amphibian Ark (AArk) would coordinate conservation activities, assess amphibian species that may go extinct, keep endangered species in captivity in suitable locations, such as zoos, and release animals into the wild when their survival can be assured.

Kevin Zippel (Amphibian Ark; )

2007-05-01

149

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

150

Serotonin involvement in the metamorphosis of the hydroid Eudendrium racemosum.  

PubMed

Hydroid planulae metamorphose in response to an inducing external stimulus, usually a bacterial cue. There is evidence that neurotransmitters participate in the signal transduction pathway of hydroid metamorphosis. Eudendrium racemosum is a colonial hydroid common in the Mediterranean Sea. It lacks the medusa stage and the planulae develop on female colonies during the fertile season. In this work, serotonin (5-HT) was localized in some planula ectodermal cells. Co-localization of serotonin and beta-tubulin suggested that 5-HT was present in sensory nervous cells and in different ectodermal cells. To investigate the role of neurotransmitters in metamorphosis, E. racemosum planulae were treated with serotonin and dopamine and with agonists and antagonists of the corresponding receptors. Serotonin and a serotonin receptor agonist induced metamorphosis, while a 5-HT receptor antagonist inhibited it. Dopamine and all dopaminergic drugs used did not show any significant effect on the onset of metamorphosis. Results from this work showed that 5-HT could stimulate metamorphosis in E. racemosum planulae in the presence of a natural inducer. A mechanism by which this neurotransmitter could act in this phase is proposed. PMID:17554682

Zega, Giuliana; Pennati, Roberta; Fanzago, Arianna; De Bernardi, Fiorenza

2007-01-01

151

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

152

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."

2012-12-20

153

Acute toxicity tests and meta-analysis identify gaps in tropical ecotoxicology for amphibians.  

PubMed

Amphibian populations are declining worldwide, particularly in tropical regions where amphibian diversity is highest. Pollutants, including agricultural pesticides, have been identified as a potential contributor to decline, yet toxicological studies of tropical amphibians are very rare. The present study assesses toxic effects on amphibians of 10 commonly used commercial pesticides in tropical agriculture using 2 approaches. First, the authors conducted 8-d toxicity assays with formulations of each pesticide using individually reared red-eyed tree frog (Agalychnis callidryas) tadpoles. Second, they conducted a review of available data for the lethal concentration to kill 50% of test animals from the US Environmental Protection Agency's ECOTOX database to allow comparison with their findings. Lethal concentration estimates from the assays ranged over several orders of magnitude. The nematicides terbufos and ethoprophos and the fungicide chlorothalonil were very highly toxic, with evident effects within an order of magnitude of environmental concentrations. Acute toxicity assays and meta-analysis show that nematicides and fungicides are generally more toxic than herbicides yet receive far less research attention than less toxic herbicides. Given that the tropics have a high diversity of amphibians, the findings emphasize the need for research into the effects of commonly used pesticides in tropical countries and should help guide future ecotoxicological research in tropical regions. PMID:24934557

Ghose, Sonia L; Donnelly, Maureen A; Kerby, Jacob; Whitfield, Steven M

2014-09-01

154

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

155

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

156

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

157

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...

158

ITRAQ MASS SPECTROMETRIC PROTEOMIC APPLICATIONS FOR IN VIVO TOXICOLOGY STUDIES OF AMPHIBIAN SPECIES: DATA HANDLING AND INTERPRETATION USING PEPTIDE-TAGGING SOFTWARE  

EPA Science Inventory

This addresses the USEPA's need for a cost effective, non-mammalian screening assay for thyroid axis disrupting chemicals; a multi-endpoint strategy combining molecular and in vivo protocols in an amphibian model is being applied at MED Duluth....

159

Stress and chytridiomycosis: exogenous exposure to corticosterone does not alter amphibian susceptibility to a fungal pathogen.  

PubMed

Recent emergence and spread of the amphibian fungal pathogen, Batrachochytrium dendrobatidis (Bd) has been attributed to a number of factors, including environmental stressors that increase host susceptibility to Bd. Physiological stress can increase circulating levels of the hormone, corticosterone, which can alter a host's physiology and affect its susceptibility to pathogens. We experimentally elevated whole-body levels of corticosterone in both larval and post-metamorphic amphibians, and subsequently tested their susceptibility to Bd. Larvae of three species were tested (Anaxyrus boreas, Rana cascadae, and Lithobates catesbeianus) and one species was tested after metamorphosis (R. cascadae). After exposure to Bd, we measured whole-body corticosterone, infection, mortality, growth, and development. We found that exposure to exogenous corticosterone had no effect on Bd infection in any species or at either life stage. Species varied in whole-body corticosterone levels and exposure to corticosterone reduced mass in A. boreas and R. cascadae larvae. Exposure to Bd did not affect mortality, but had a number of sublethal effects. Across species, larvae exposed to Bd had higher corticosterone levels than unexposed larvae, but the opposite pattern was found in post-metamorphic R. cascadae. Bd exposure also increased larval length in all species and increased mass in R. cascadae larvae. Our results indicate that caution is warranted in assuming a strong link between elevated levels of corticosterone and disease susceptibility in amphibians. The role of physiological stress in altering Bd prevalence in amphibian populations is likely much more complicated than can be explained by examining a single "stress" endpoint. PMID:24610865

Searle, Catherine L; Belden, Lisa K; Du, Pang; Blaustein, Andrew R

2014-06-01

160

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

161

Herpetological Review 43(2), 2012 AMPHIBIAN DISEASES 293  

E-print Network

in amphibian declines. PLoS Biol. 6:441­454. rrrrr . / 6)%7)6 & ) =392+ %2( 6 -&»�)> . Amphibian Moni- toring(6-59)7 ( L. FISCHMAN, AND R.W.WALLER. 2004. Status and trends of amphibian declines and extinctions worldwideHerpetological Review 43(2), 2012 AMPHIBIAN DISEASES 293 trade in amphibians and introduced

Gray, Matthew

162

Pesticide mixtures, endocrine disruption, and amphibian declines: are we underestimating the impact?  

PubMed

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

2006-04-01

163

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

164

Dynamic mechanical oscillations during metamorphosis of the monarch butterfly.  

PubMed

The mechanical oscillation of the heart is fundamental during insect metamorphosis, but it is unclear how morphological changes affect its mechanical dynamics. Here, the micromechanical heartbeat with the monarch chrysalis (Danaus plexippus) during metamorphosis is compared with the structural changes observed through in vivo magnetic resonance imaging (MRI). We employ a novel ultra-sensitive detection approach, optical beam deflection, in order to measure the microscale motions of the pupae during the course of metamorphosis. We observed very distinct mechanical contractions occurring at regular intervals, which we ascribe to the mechanical function of the heart organ. Motion was observed to occur in approximately 15 min bursts of activity with frequencies in the 0.4-1.0 Hz range separated by periods of quiescence during the first 83 per cent of development. In the final stages, the beating was found to be uninterrupted until the adult monarch butterfly emerged. Distinct stages of development were characterized by changes in frequency, amplitude, mechanical quality factor and de/repolarization times of the mechanical pulsing. The MRI revealed that the heart organ remains functionally intact throughout metamorphosis but undergoes morphological changes that are reflected in the mechanical oscillation. PMID:18682363

Pelling, Andrew E; Wilkinson, Paul R; Stringer, Richard; Gimzewski, James K

2009-01-01

165

Embryonic development and metamorphosis of the scyphozoan Aurelia.  

PubMed

We investigated the development of Aurelia (Cnidaria, Scyphozoa) during embryogenesis and metamorphosis into a polyp, using antibody markers combined with confocal and transmission electron microscopy. Early embryos form actively proliferating coeloblastulae. Invagination is observed during gastrulation. In the planula, (1) the ectoderm is pseudostratified with densely packed nuclei arranged in a superficial and a deep stratum, (2) the aboral pole consists of elongated ectodermal cells with basally located nuclei forming an apical organ, which is previously only known from anthozoan planulae, (3) endodermal cells are large and highly vacuolated, and (4) FMRFamide-immunoreactive nerve cells are found exclusively in the ectoderm of the aboral region. During metamorphosis into a polyp, cells in the planula endoderm, but not in the ectoderm, become strongly caspase 3 immunoreactive, suggesting that the planula endoderm, in part or in its entirety, undergoes apoptosis during metamorphosis. The polyp endoderm seems to be derived from the planula ectoderm in Aurelia, implicating the occurrence of "secondary" gastrulation during early metamorphosis. PMID:18850238

Yuan, David; Nakanishi, Nagayasu; Jacobs, David K; Hartenstein, Volker

2008-10-01

166

Dynamic mechanical oscillations during metamorphosis of the monarch butterfly  

PubMed Central

The mechanical oscillation of the heart is fundamental during insect metamorphosis, but it is unclear how morphological changes affect its mechanical dynamics. Here, the micromechanical heartbeat with the monarch chrysalis (Danaus plexippus) during metamorphosis is compared with the structural changes observed through in vivo magnetic resonance imaging (MRI). We employ a novel ultra-sensitive detection approach, optical beam deflection, in order to measure the microscale motions of the pupae during the course of metamorphosis. We observed very distinct mechanical contractions occurring at regular intervals, which we ascribe to the mechanical function of the heart organ. Motion was observed to occur in approximately 15?min bursts of activity with frequencies in the 0.4–1.0?Hz range separated by periods of quiescence during the first 83 per cent of development. In the final stages, the beating was found to be uninterrupted until the adult monarch butterfly emerged. Distinct stages of development were characterized by changes in frequency, amplitude, mechanical quality factor and de/repolarization times of the mechanical pulsing. The MRI revealed that the heart organ remains functionally intact throughout metamorphosis but undergoes morphological changes that are reflected in the mechanical oscillation. PMID:18682363

Pelling, Andrew E; Wilkinson, Paul R; Stringer, Richard; Gimzewski, James K

2008-01-01

167

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

168

Coral larvae under ocean acidification: survival, metabolism, and metamorphosis.  

PubMed

Ocean acidification may negatively impact the early life stages of some marine invertebrates including corals. Although reduced growth of juvenile corals in acidified seawater has been reported, coral larvae have been reported to demonstrate some level of tolerance to reduced pH. We hypothesize that the observed tolerance of coral larvae to low pH may be partly explained by reduced metabolic rates in acidified seawater because both calcifying and non-calcifying marine invertebrates could show metabolic depression under reduced pH in order to enhance their survival. In this study, after 3-d and 7-d exposure to three different pH levels (8.0, 7.6, and 7.3), we found that the oxygen consumption of Acropora digitifera larvae tended to be suppressed with reduced pH, although a statistically significant difference was not observed between pH conditions. Larval metamorphosis was also observed, confirming that successful recruitment is impaired when metamorphosis is disrupted, despite larval survival. Results also showed that the metamorphosis rate significantly decreased under acidified seawater conditions after both short (2 h) and long (7 d) term exposure. These results imply that acidified seawater impacts larval physiology, suggesting that suppressed metabolism and metamorphosis may alter the dispersal potential of larvae and subsequently reduce the resilience of coral communities in the near future as the ocean pH decreases. PMID:21264208

Nakamura, Masako; Ohki, Shun; Suzuki, Atsushi; Sakai, Kazuhiko

2011-01-01

169

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

170

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

2015-04-01

171

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

172

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

173

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

174

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...

175

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

176

Troponin T isoform expression is modulated during Atlantic Halibut metamorphosis  

PubMed Central

Background Flatfish metamorphosis is a thyroid hormone (TH) driven process which leads to a dramatic change from a symmetrical larva to an asymmetrical juvenile. The effect of THs on muscle and in particular muscle sarcomer protein genes is largely unexplored in fish. The change in Troponin T (TnT), a pivotal protein in the assembly of skeletal muscles sarcomeres and a modulator of calcium driven muscle contraction, during flatfish metamophosis is studied. Results In the present study five cDNAs for halibut TnT genes were cloned; three were splice variants arising from a single fast TnT (fTnT) gene; a fourth encoded a novel teleost specific fTnT-like cDNA (AfTnT) expressed exclusively in slow muscle and the fifth encoded the teleost specific sTnT2. THs modified the expression of halibut fTnT isoforms which changed from predominantly basic to acidic isoforms during natural and T4 induced metamorphosis. In contrast, expression of red muscle specific genes, AfTnT and sTnT2, did not change during natural metamorphosis or after T4 treatment. Prior to and after metamorphosis no change in the dorso-ventral symmetry or temporal-spatial expression pattern of TnT genes and muscle fibre organization occurred in halibut musculature. Conclusion Muscle organisation in halibut remains symmetrical even after metamorphosis suggesting TH driven changes are associated with molecular adaptations. We hypothesize that species specific differences in TnT gene expression in teleosts underlies different larval muscle developmental programs which better adapts them to the specific ecological constraints. PMID:17577411

Campinho, Marco A; Silva, Nádia; Nowell, Mari A; Llewellyn, Lynda; Sweeney, Glen E; Power, Deborah M

2007-01-01

177

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

178

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

179

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.

180

Amphibian Research and Monitoring Initiative (ARMI)  

Microsoft Academic Search

Abstract. Most research to assess amphibian,declines has focused on local-scale projects on one or a few species. The Amphibian Research and Monitoring Initiative (ARMI) is a national program,in the United States mandated,by congressional directive and implemented,by the U.S. Department of the Interior (specifically the U.S. Geological Survey, USGS). Program goals are to monitor changes in populations of amphibians,across U.S. Department

Erin Muths; Robin E. Jung; Larissa L. Bailey; Michael J. Adams; P. Stephen Corn; C. Kenneth Dodd; G Ary M. Fellers; Walter J. Sadinski; Cecil R. Schwalbe; Susan C. Walls; Robert N. Fisher; Alisa L. Gallant; William A. Battaglin; D. Earl Green

181

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

182

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

183

Evolution of the Amphibian Ear  

Microsoft Academic Search

\\u000a Most amphibians have within their ears the substrate to hear efficiently underwater, underground, and in air, a talent few\\u000a if any other vertebrates can lay claim to. They have achieved this by being very conservative in the nature of novel addition\\u000a s and specialized adaptations to their ears. Indeed, regressive events appear to be just as common as progressive trends

Michael Smotherman; Peter Narins

184

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

E-print Network

can be applied to many aquatic amphibians, fish, or reptiles such as crocodilians. DOI: 10.1103/Phys is a mechanoreceptive system of aquatic amphibians and fish. It is used to detect water movements along the animal prey. Aquatic amphibians such as Xenopus [5] possess about 180 lateral­line organs distributed

Mills, L. Scott

185

Impending conservation crisis for Southeast Asian amphibians  

PubMed Central

With an understudied amphibian fauna, the highest deforestation rate on the planet and high harvesting pressures, Southeast Asian amphibians are facing a conservation crisis. Owing to the overriding threat of habitat loss, the most critical conservation action required is the identification and strict protection of habitat assessed as having high amphibian species diversity and/or representing distinctive regional amphibian faunas. Long-term population monitoring, enhanced survey efforts, collection of basic biological and ecological information, continued taxonomic research and evaluation of the impact of commercial trade for food, medicine and pets are also needed. Strong involvement of regional stakeholders, students and professionals is essential to accomplish these actions. PMID:20007165

Rowley, Jodi; Brown, Rafe; Bain, Raoul; Kusrini, Mirza; Inger, Robert; Stuart, Bryan; Wogan, Guin; Thy, Neang; Chan-ard, Tanya; Trung, Cao Tien; Diesmos, Arvin; Iskandar, Djoko T.; Lau, Michael; Ming, Leong Tzi; Makchai, Sunchai; Truong, Nguyen Quang; Phimmachak, Somphouthone

2010-01-01

186

Amphibians at risk? Susceptibility of terrestrial amphibian life stages to pesticides.  

PubMed

Current pesticide risk assessment does not specifically consider amphibians. Amphibians in the aquatic environment (aquatic life stages or postmetamorphic aquatic amphibians) and terrestrial living juvenile or adult amphibians are assumed to be covered by the risk assessment for aquatic invertebrates and fish, or mammals and birds, respectively. This procedure has been evaluated as being sufficiently protective regarding the acute risk posed by a number of pesticides to aquatic amphibian life stages (eggs, larvae). However, it is unknown whether the exposure and sensitivity of terrestrial living amphibians are comparable to mammalian and avian exposure and sensitivity. We reviewed the literature on dermal pesticide absorption and toxicity studies for terrestrial life stages of amphibians, focusing on the dermal exposure pathway, that is, through treated soil or direct overspray. In vitro studies demonstrated that cutaneous absorption of chemicals is significant and that chemical percutaneous passage, P (cm/h), is higher in amphibians than in mammals. In vivo, the rapid and substantial uptake of the herbicide atrazine from treated soil by toads (Bufo americanus) has been described. Severe toxic effects on various amphibian species have been reported for field-relevant application rates of different pesticides. In general, exposure and toxicity studies for terrestrial amphibian life stages are scarce, and the reported data indicate the need for further research, especially in light of the global amphibian decline. PMID:21898550

Brühl, Carsten A; Pieper, Silvia; Weber, Brigitte

2011-11-01

187

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

2015-03-01

188

Homeodomain POU and Abd-A proteins regulate the transcription of pupal genes during metamorphosis of the silkworm, Bombyx mori  

PubMed Central

A cascade of 20-hydroxyecdysone–mediated gene expression and repression initiates larva-to-pupa metamorphosis. We recently showed that two transcription factors, BmPOUM2 and Bm?FTZ-F1, bind to the cis-regulatory elements in the promoter of the gene coding for cuticle protein, BmWCP4, and regulate its expression during Bombyx mori metamorphosis. Here we show that down-regulation of BmPOUM2 expression by RNA interference during the wandering stage resulted in failure to complete metamorphosis. The thorax epidermis of RNA interference-treated larvae became transparent, wing disc growth and differentiation were arrested, and the larvae failed to spin cocoons. Quantitative real-time PCR analysis showed that expression of the genes coding for pupal-specific wing cuticle proteins BmWCP1, BmWCP2, BmWCP3, BmWCP4, BmWCP5, BmWCP6, BmWCP8, and BmWCP9 were down-regulated in BmPOUM2 dsRNA-treated animals, whereas overexpression of BmPOUM2 protein increased the expression of BmWCP4, BmWCP5, BmWCP6, BmWCP7, and BmWCP8. Pull-down assays, far-Western blot, and electrophoretic mobility shift assay showed that the BmPOUM2 protein interacted with another homeodomain transcription factor, BmAbd-A, to induce the expression of BmWCP4. Immunohistochemical localization of BmPOUM2, BmAbd-A, and BmWCP4 proteins revealed that BmAbd-A and BmPOUM2 proteins are colocalized in the wing disc cell nuclei, whereas BmWCP4 protein is localized in the cytoplasm. Together these data suggest that BmPOUM2 interacts with the homeodomain transcription factor BmAbd-A and regulates the expression of BmWCP4 and probably other BmWCPs to complete the larva-to-pupa transformation. Although homeodomain proteins are known to regulate embryonic development, this study showed that these proteins also regulate metamorphosis. PMID:22802616

Deng, Huimin; Zhang, Jialing; Li, Yong; Zheng, Sichun; Liu, Lin; Huang, Lihua; Xu, Wei-Hua; Palli, Subba R.; Feng, Qili

2012-01-01

189

Amphibians and Reptiles of Los Alamos County  

Microsoft Academic Search

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

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

1999-01-01

190

Origin of the Amphibian Chytrid Fungus  

Microsoft Academic Search

The sudden appearance of chytridiomycosis, the cause of amphibian deaths and population declines in sev- eral continents, suggests that its etiologic agent, the amphibian chytrid Batrachochytrium dendrobatidis, was introduced into the affected regions. However, the origin of this virulent pathogen is unknown. A survey was conducted of 697 archived specimens of 3 species of Xenopus col- lected from 1879 to

Ché Weldon; Louis H. du Preez; Alex D. Hyatt; Reinhold Muller; Rick Speare

191

AMPHIBIANS AS BIOINDICATORS OF WETLAND CONDITION  

EPA Science Inventory

King county has over ten years of data on the distribution and abundance of amphibians in wetlands. Changes in wetland amphibian composition are being analyzed in relationship to physical changes within wetlands and surrounding land-use development and change. In addition to tes...

192

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

193

Cartilage on the move: cartilage lineage tracing during tadpole metamorphosis.  

PubMed

The reorganization of cranial cartilages during tadpole metamorphosis is a set of complex processes. The fates of larval cartilage-forming cells (chondrocytes) and sources of adult chondrocytes are largely unknown. Individual larval cranial cartilages may either degenerate or remodel, while many adult cartilages appear to form de novo during metamorphosis. Determining the extent to which adult chondrocytes/cartilages are derived from larval chondrocytes during metamorphosis requires new techniques in chondrocyte lineage tracing. We have developed two transgenic systems to label cartilage cells throughout the body with fluorescent proteins. One system strongly labels early tadpole cartilages only. The other system inducibly labels forming cartilages at any developmental stage. We examined cartilages of the skull (viscero- and neurocranium), and identified larval cartilages that either resorb or remodel into adult cartilages. Our data show that the adult otic capsules, tecti anterius and posterius, hyale, and portions of Meckel's cartilage are derived from larval chondrocytes. Our data also suggest that most adult cartilages form de novo, though we cannot rule out the potential for extreme larval chondrocyte proliferation or de- and re-differentiation, which could dilute our fluorescent protein signal. The transgenic lineage tracing strategies developed here are the first examples of inducible, skeleton-specific, lineage tracing in Xenopus. PMID:23036161

Kerney, Ryan R; Brittain, Alison L; Hall, Brian K; Buchholz, Daniel R

2012-10-01

194

Arrested development in Xenopus laevis tadpoles: how size constrains metamorphosis.  

PubMed

Xenopus laevis tadpoles that arrest development and remain as larvae for several years sometimes occur spontaneously in laboratory populations. These tadpoles cease development at an early hindlimb stage, but continue to grow and develop into grossly deformed giants. Giant tadpoles lack thyroid glands, and differ in morphology and behaviour from normal larvae. They are negatively buoyant, typically with small and partially solidified lungs, and have greatly enlarged fat bodies. Giant tadpoles have mature gonads with eggs and sperm, whereas normal tadpoles of the same stage have undifferentiated gonads. Larval reproduction has never been reported in anurans, but gonadal development decoupled from metamorphosis brings these giants the closest of any anurans to being truly neotenic. We discuss behavioural and morphological factors that may hinder both reproduction in giant Xenopus larvae and the evolution of neoteny in anurans in general. Experimental treatment with exogenous thyroid hormone induces some, but not complete, metamorphic changes in these giants. The limbs and head progress through metamorphosis; however, all tadpoles die at the stage when the tail would normally be resorbed. The disproportionate growth of tissues and organs in giant tadpoles may preclude complete metamorphosis, even under exogenous thyroid hormone induction. PMID:15143146

Rot-Nikcevic, Irena; Wassersug, Richard J

2004-05-01

195

Time and size at metamorphosis related to adult fitness in Ambystoma talpoideum  

SciTech Connect

The relationships among timing of metamorphosis, size at metamorphosis, and traits related to adult fitness were studied for 8 yr in the salamander Ambystoma talpoideum at a temporary pond. Among years, the modal time of metamorphosis and mean body size at metamorphosis were positively correlated with the date the pond dried. In years that the pond dried late, one group of larvae metamorphosed well before the pond dried, whereas the other group metamorphosed just before pond drying. Mean body size of late-metamorphosing individuals was not greater than that of individuals metamorphosing early. Early-metamorphosing males and females were larger at first and second reproduction than were late-metamorphosing individuals. Independent of timing of metamorphosis, larger juveniles at metamorphosis were also larger adults at first reproduction. Age at first reproduction for males was not associated with timing of or size at metamorphosis but large early-metamorphosing females reproduced at a younger age than did small early-metamorphosing females. Neither time of metamorphosis nor size at metamorphosis was associated with survival to first reproduction. These results demonstrate a direct relationship between phenotypic variation generated in the larval stage and adult traits closely associated with an individual's fitness.

Semlitsch, R.D.; Scott, D.E.; Pechmann, J.H.K.

1988-02-01

196

Amphibian declines in the twenty-first century: why we need assisted reproductive technologies.  

PubMed

Each amphibian species is evolutionarily distinct, having developed highly specialized and diverse reproductive strategies in both terrestrial and aquatic environments. These unique reproductive patterns and mechanisms, key to species propagation, have only been explored in a limited number of laboratory models. Although the development of applied reproductive technologies for amphibians has proven useful for a few threatened species, the real benefit of this technology has been new insights into the reproductive adaptations, behavior, endocrinology, and physiological mechanisms that have evolved over millions of years. As the basic fundamental database on amphibian reproductive physiology has grown, so has the applied benefit for species conservation. In particular, technologies such as non-invasive fecal and urinary hormone assays, hormone treatments for induced breeding or gamete collection, in vitro fertilization, and the ability to establish genome resource banks have all played important roles in monitoring or managing small populations of captive species. Amphibians have the ability to produce a large excess of germplasm (up to 10,000 ovulated eggs in a single reproductive event) that if not collected and preserved, would represent a wasted valuable resource. We discuss the current state of knowledge in assisted reproductive technologies for amphibians and why their extinction crisis means these available tools can no longer be implemented as small-scale, last-ditch efforts. The reproductive technologies must be established early as a key component of large-scale species recovery. PMID:25091914

Clulow, John; Trudeau, Vance L; Kouba, Andrew J

2014-01-01

197

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

198

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

199

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.

200

Amphibian Decline or Extinction? Current Declines Dwarf Background Extinction Rate  

Microsoft Academic Search

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 to the background amphibian extinction rate from the fossil record has not been well studied. I compared current amphibian extinction rates with their reported background extinction rates using standard and fuzzy arithmetic. These calculations suggest

Malcolm L. McCallum

2007-01-01

201

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

202

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

203

Heavy metals alter the survival, growth, metamorphosis, and antipredatory behavior of Columbia spotted frog (Rana luteiventris) tadpoles.  

PubMed

Amphibian populations appear to be declining around the world. Although there is no single cause, one factor may be pollution from heavy metals. As a result of mining in the Silver Valley of Idaho, heavy metals have been released into habitats containing many species of sensitive organisms, including spotted frogs (Rana luteiventris). While the gross extent of pollution has been well documented, the more subtle behavioral effects of heavy metals such as lead, zinc, and cadmium are less well studied. We tested the effects of heavy metals on the short-term survival (LC50) of spotted frog tadpoles. Compared to single metals, metals presented together were toxic at lower doses. We also raised the tadpoles in outdoor mini-ecosystems containing either a single heavy metal or soil from an EPA Superfund site in the Silver Valley known to be composed of numerous heavy metals. Exposure to Silver Valley soil resulted in delayed metamorphosis. We tested the ability of metal-exposed tadpoles to detect and respond to chemical cues emanating from predacious rainbow trout. We found that high levels of Silver Valley soil, medium levels of zinc, and medium and high levels of lead resulted in a decreased fright response. Low levels of cadmium, zinc, and lead did not cause a significant effect, but low levels of soil did result in a decreased fright response. Heavy metals may alter interactions between tadpoles and their predators. PMID:9732476

Lefcort, H; Meguire, R A; Wilson, L H; Ettinger, W F

1998-10-01

204

Nutrition and health in amphibian husbandry.  

PubMed

Amphibian biology is intricate, and there are many inter-related factors that need to be understood before establishing successful Conservation Breeding Programs (CBPs). Nutritional needs of amphibians are highly integrated with disease and their husbandry needs, and the diversity of developmental stages, natural habitats, and feeding strategies result in many different recommendations for proper care and feeding. This review identifies several areas where there is substantial room for improvement in maintaining healthy ex situ amphibian populations specifically in the areas of obtaining and utilizing natural history data for both amphibians and their dietary items, achieving more appropriate environmental parameters, understanding stress and hormone production, and promoting better physical and population health. Using a scientific or research framework to answer questions about disease, nutrition, husbandry, genetics, and endocrinology of ex situ amphibians will improve specialists' understanding of the needs of these species. In general, there is a lack of baseline data and comparative information for most basic aspects of amphibian biology as well as standardized laboratory approaches. Instituting a formalized research approach in multiple scientific disciplines will be beneficial not only to the management of current ex situ populations, but also in moving forward with future conservation and reintroduction projects. This overview of gaps in knowledge concerning ex situ amphibian care should serve as a foundation for much needed future research in these areas. PMID:25296396

Ferrie, Gina M; Alford, Vance C; Atkinson, Jim; Baitchman, Eric; Barber, Diane; Blaner, William S; Crawshaw, Graham; Daneault, Andy; Dierenfeld, Ellen; Finke, Mark; Fleming, Greg; Gagliardo, Ron; Hoffman, Eric A; Karasov, William; Klasing, Kirk; Koutsos, Elizabeth; Lankton, Julia; Lavin, Shana R; Lentini, Andrew; Livingston, Shannon; Lock, Brad; Mason, Tom; McComb, Alejandra; Morris, Cheryl; Pessier, Allan P; Olea-Popelka, Francisco; Probst, Tom; Rodriguez, Carlos; Schad, Kristine; Semmen, Kent; Sincage, Jamie; Stamper, M Andrew; Steinmetz, Jason; Sullivan, Kathleen; Terrell, Scott; Wertan, Nina; Wheaton, Catharine J; Wilson, Brad; Valdes, Eduardo V

2014-01-01

205

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.

206

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

207

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

208

Pathogenesis, diagnosis, and treatment of amphibian chytridiomycosis.  

PubMed

Chytridiomycosis, caused by the chytridiomycete fungus, Batrachochytrium dendrobatidis, is an important pathogen of amphibians in captivity and is a major concern for global conservation of amphibians. The organism infects keratinized epithelial cells of amphibian skin and causes disease and mortality by interfering with important skin functions, especially electrolyte balance. Primary treatments are with antifungal medications applied in a topical bath solution, and itraconazole is the most commonly used agent, although several different options are available. Supportive treatment of the clinically ill patient is necessary for success, with particular attention to electrolyte therapy. PMID:24018031

Baitchman, Eric J; Pessier, Allan P

2013-09-01

209

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.

210

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 ...

211

Induction of settlement and metamorphosis of Cnidarian larvae: Signals and signal transduction  

Microsoft Academic Search

Settlement and metamorphosis are induced by environmental cues in many marine invertebrates. These signals emanate from biotic or abiotic material indicating the presence of a suitable habitat. In Cnidarians, pelagic larvae undergo metamorphosis to a sessile polyp. Environmental signals reactivate the morphogenetically inactive larvae and internal mechanisms are turned onto coordinate the development of the polyp. In recent years developmental

THOMAS LEITZ

1997-01-01

212

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

213

Growth rates and size at metamorphosis of high elevation populations of Ambystoma tigrinum  

Microsoft Academic Search

The role of temperature in determining the alternative life history sequences in high elevation populations of Ambystoma tigrinum is given a physiological base. Growth rates of larval populations increase with increased average pond temperatures whereas sizes of the larvae at metamorphosis decrease with increased average pond temperatures. This results in a negative correlation between growth rate and size at metamorphosis

John R. Bizer

1978-01-01

214

INDUCTION OF METAMORPHOSIS BY ECDYSONE ANALOGUES: DROSOPHILA IMAGINAL DISCS CULTURED IN VIVO  

Microsoft Academic Search

The imaginal discs of Drosophila provide an increasingly attractive system for the study of development (see e.g., Gehring, 1968) . One such developmental problem is the hormonal control of metamorphosis. This problem and others could be investigated more easily if metamorphosis could be induced in vitro. The early literature on the somewhat disappointing attempts at in vitro culture of insect

JOHN H. POSTLETHWAIT

1970-01-01

215

EVIDENCE FOR FIRST YEAR METAMORPHOSIS OF BULLFROGS IN AN EPHEMERAL POND  

EPA Science Inventory

It is widely accepted that bullfrog ( R catesbeiana) tadpoles in the Pacific Northwest require more than one year for metamorphosis. Often time to metamorphosis increases along a latitudinal gradient. During our pond surveys at the EE Wilson Reserve, we found evidence of first ...

216

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

Microsoft Academic Search

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

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

2009-01-01

217

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

218

Induction of Metamorphosis of Larvae of the Green Sea Urchin, Strongylocentrotus droebachiensis, by Coralline Red Algae  

Microsoft Academic Search

The coralline red algae, Lithothumnion gla- ciale, Phymatolithon luevigat urn, P. rugulosum, and Cor- allinu ollicinulis, induced >85% of laboratory-reared lar- vae of Strongyloccntrotus droehachiensis to metamor- phose. Larvae must contact live L. glaciale or its spores for metamorphosis to occur: the inducer is not sensed in the water column. However, aqueous extracts of L. gfu- ciule can induce metamorphosis,

CHRISTOPHER M. PEARCE; ROBERT E. SCHEIBLING

1990-01-01

219

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

220

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

221

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

PubMed

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 such as CsCl ions, diacylglycerol and bacterial inducers). Our results show further that RFamides act downstream of LWamide release, presumably directly on target cells mediating metamorphosis. These observations support a model in which metamorphosis in H. echinata is regulated by sensory neurons secreting LWamides and RFamides in response to environmental cues. PMID:14586653

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

2003-12-01

222

Protein tyrosine phosphatase encoded in Cotesia plutellae bracovirus suppresses a larva-to-pupa metamorphosis of the diamondback moth, Plutella xylostella.  

PubMed

Parasitization by an endoparasitoid wasp, Cotesia plutellae, inhibits a larva-to-pupa metamorphosis of the diamondback moth, Plutella xylostella. This study tested an inhibitory effect of C. plutellae bracovirus (CpBV) on the metamorphosis of P. xylostella. Parasitized P. xylostella exhibited significantly reduced prothoracic gland (PTG) development at the last instar compared to nonparasitized larvae. Expression of the ecdysone receptor (EcR) was markedly suppressed during the last instar larvae parasitized by C. plutellae. By contrast, expression of the insulin receptor (InR) significantly increased in the parasitized larvae. Microinjection of CpBV significantly inhibited the larva-to-pupa metamorphosis of nonparasitized larvae in a dose-dependent manner. Injection of CpBV also inhibited the expression of the EcR and increased the expression of the InR. Individual CpBV segments were transiently expressed in its encoded genes in nonparasitized larvae and screened to determine antimetamorphic viral gene(s). Out of 21 CpBV segments, two viral segments (CpBV-S22 and CpBV-S27) were proved to inhibit larva-to-pupa metamorphosis by transient expression assay. RNA interference of each gene encoded in the viral segments was applied to determine antimetamorphic gene(s). Protein tyrosine phosphatase, early expressed gene, and four hypothetical genes were selected to be associated with the antimetamorphic activity of CpBV. These results suggest that antimetamorphosis of P. xylostella parasitized by C. plutellae is induced by inhibiting PTG development and subsequent ecdysteroid signaling with viral factors of CpBV. PMID:23651929

Kim, Jiwan; Hepat, Rahul; Lee, Daeweon; Kim, Yonggyun

2013-09-01

223

Neuronal cell death during metamorphosis of Hydractina echinata (Cnidaria, Hydrozoa).  

PubMed

In planula larvae of the invertebrate Hydractinia echinata (Cnidaria, Hydrozoa), peptides of the GLWamide and the RFamide families are expressed in distinct subpopulations of neurons, distributed in a typical spatial pattern through the larval body. However, in the adult polyp GLWamide or RFamide-expressing cells are located at body parts that do not correspond to the prior larval regions. Since we had shown previously that during metamorphosis a large number of cells are removed by programmed cell death (PCD), we aimed to analyze whether cells of the neuropeptide-expressing larval nerve net are among those sacrificed. By immunohistochemical staining and in situ hybridization, we labeled GLWamide- and RFamide-expressing cells. Double staining of neuropeptides and degraded DNA (TUNEL analysis) identified some neurosensory cells as being apoptotic. Derangement of the cytoplasm and rapid destruction of neuropeptide precursor RNA indicated complete death of these particular sensory cells in the course of metamorphosis. Additionally, a small group of RFamide-positive sensory cells in the developing mouth region of the primary polyp could be shown to emerge by proliferation. Our results support the idea that during metamorphosis, specific parts of the larval neuronal network are subject to neurodegeneration and therefore not used for construction of the adult nerve net. Most neuronal cells of the primary polyp arise by de novo differentiation of stem cells commited to neural differentiation in embryogenesis. At least some nerve cells derive from proliferation of progenitor cells. Clarification of how the nerve net of these basal eumetazoans degenerates may add information to the understanding of neurodegeneration by apoptosis as a whole in the animal kingdom. PMID:21104287

Seipp, Stefanie; Schmich, Jürgen; Will, Britta; Schetter, Eva; Plickert, Günter; Leitz, Thomas

2010-12-01

224

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

225

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

226

Climate Variability in Regions of Amphibian Declines  

Microsoft Academic Search

We explored the relationship between amphibian declines and climate variations in Colorado (U.S.A.), Puerto Rico, Costa Rica-Panama, and Queensland (Australia) through two sources of data: output from the National Center for Environmental Prediction \\

Michael A. Alexander; Jon K. Eischeid

2001-01-01

227

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

228

Journal of Herpetology, Vol. 38, No. 1, pp. 149152, 2004 Copyright 2004 Society for the Study of Amphibians and Reptiles  

E-print Network

of Amphibians and Reptiles Identification of a Neurotoxic Venom Component in the Tiger Rattlesnake, Crotalus.--Previous toxicological and immunology assays have strongly suggested that a neurotoxic component is present in the venom the presence of both subunits. Venom collected from five of the 18 snakes that provided blood samples were

Husak, Jerry F.

229

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

230

Phylogenetic distribution of symbiotic bacteria from Panamanian amphibians that inhibit growth of the lethal fungal pathogen Batrachochytrium dendrobatidis.  

PubMed

The introduction of next-generation sequencing has allowed for greater understanding of community composition of symbiotic microbial communities. However, determining the function of individual members of these microbial communities still largely relies on culture-based methods. Here, we present results on the phylogenetic distribution of a defensive functional trait of cultured symbiotic bacteria associated with amphibians. Amphibians are host to a diverse community of cutaneous bacteria and some of these bacteria protect their host from the lethal fungal pathogen Batrachochytrium dendrobatidis (Bd) by secreting antifungal metabolites. We cultured over 450 bacterial isolates from the skins of Panamanian amphibian species and tested their interactions with Bd using an in vitro challenge assay. For a subset of isolates, we also completed coculture experiments and found that culturing isolates with Bd had no effect on inhibitory properties of the bacteria, but it significantly decreased metabolite secretion. In challenge assays, approximately 75% of the bacterial isolates inhibited Bd to some extent and these inhibitory isolates were widely distributed among all bacterial phyla. Although there was no clear phylogenetic signal of inhibition, three genera, Stenotrophomonas, Aeromonas and Pseudomonas, had a high proportion of inhibitory isolates (100%, 77% and 73%, respectively). Overall, our results demonstrate that antifungal properties are phylogenetically widespread in symbiotic microbial communities of Panamanian amphibians and that some functional redundancy for fungal inhibition occurs in these communities. We hope that these findings contribute to the discovery and development of probiotics for amphibians that can mitigate the threat of chytridiomycosis. PMID:25737297

Becker, Matthew H; Walke, Jenifer B; Murrill, Lindsey; Woodhams, Douglas C; Reinert, Laura K; Rollins-Smith, Louise A; Burzynski, Elizabeth A; Umile, Thomas P; Minbiole, Kevin P C; Belden, Lisa K

2015-04-01

231

Surveys of calling amphibians in North Dakota  

USGS Publications Warehouse

Amphibians have received increased attention in recent years from the scientific community and general public alike. Many populations throughout the world have declined, or have been extirpated, often without an apparent cause. Concern about the status of amphibians has translated into a growing interest in systematic and statistically sound monitoring programs. Several extensive efforts to monitor populations of calling amphibians are in place, and more are under development. Necessary for the design of appropriate surveys is an understanding of the behavior, especially vocalization, of the various species, and how it varies by geographic location and environmental conditions. In 1995 we conducted roadside surveys of calling amphibians along 44 routes in North Dakota. We describe results of that survey, with special attention given to variables that influence detectability of calling amphibians. Unlike similar studies, we accounted for the amount of time observers spent listening for amphibians under different conditions. We found that the optimal conditions for a single survey for North Dakota in that year would be in early June, between the hours of 2300 and 0130, with ambient temperatures above 13 deg. C, and with no rain and little or no wind or moonlight. Multiple surveys in a year would yield better results, of course, especially for the wood frog (Rana sylvatica), which is most active earlier in the season. Studies such as ours should be replicated in space and time to ensure a well-designed survey.

Johnson, D.H.; Batie, R.D.

2001-01-01

232

Can protected mountain areas serve as refuges for declining amphibians? Potential threats of climate change and amphibian chytridiomycosis in an alpine amphibian  

E-print Network

Can protected mountain areas serve as refuges for declining amphibians? Potential threats Hödl Keywords: alpine habitats, amphibian declines, Bufo bufo, chytridiomycosis, explosive breeding (Schabetsberger 1995, Schabetsberger et al. 2004; Gutleb 2005). Some of the most worry- ing amphibian declines

Hödl, Walter

233

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

234

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

235

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

236

Chytridiomycosis survey in wild and captive mexican amphibians.  

PubMed

Mexico, a rich country in terms of amphibian diversity, hosts about 375 described species. Population declines have been documented for several species where it is evident that their habitat is being destroyed or modified. However, other species which inhabit pristine areas are declining as well. It has been suggested that the chytrid fungus Batrachochytrium dendrobatidis (B.d.) may be one of the causes of the enigmatic declines in Mexico. We surveyed a total of 45 localities, in 12 states across Mexico, examining a total of 360 specimens representing 14 genera and 30 species. We also examined 91 specimens of Ambystoma mexicanum from a captive population in Mexico City as well as one Pachymedusa dacnicolor obtained in a pet shop. We used a two-tiered technique to detect the pathogen. For wild-caught specimens, we utilized light microscopy to identify presence of B.d. sporangia in amphibian skin. Then, to verify the infection, we used a quantitative real-time PCR assay on collected skin sections which is specific for B.d. For captive animals, we used a nonlethal version of the real-time PCR technique. We found evidence of B.d. infection in 111 animals comprising 14 species in 13 localities. A large percentage (84%) of Ambystoma mexicanum from the colony were infected with B.d. The two most highly infected individuals were the endangered Ambystoma mexicanum, from a captive colony, and Pachymedusa dacnicolor, purchased at a pet shop. PMID:18648793

Frías-Alvarez, Patricia; Vredenburg, Vance T; Familiar-López, Mariel; Longcore, Joyce E; González-Bernal, Edna; Santos-Barrera, Georgina; Zambrano, Luis; Parra-Olea, Gabriela

2008-03-01

237

Establishing a baseline and faunal history in amphibian monitoring programs: The amphibians of Harris Neck, GA  

USGS Publications Warehouse

We conducted an intensive inventory of Harris Neck National Wildlife Refuge in coastal Georgia to determine the feasibility of establishing an amphibian monitoring program at this location. Thirteen semi-aquatic amphibian species were identified at 21 locations. Amphibian species richness at Harris Neck was similar to that of nearby barrier islands. The amphibian fauna of Harris Neck has long been affected by human-induced landscape changes, including the inadvertent introduction of tadpoles from distant fish hatcheries and the creation of artificial impoundments. Land-use history provides important information necessary to understand current amphibian distribution, especially when census data are used to establish a baseline from which to monitor future status and trends.

Dodd, C.K., Jr.; Barichivich, W.J.

2007-01-01

238

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

239

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

240

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

241

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

242

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

243

50 CFR 17.43 - Special rules-amphibians.  

Code of Federal Regulations, 2014 CFR

... 2014-10-01 2014-10-01 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 )....

2014-10-01

244

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

245

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...

246

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

247

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

248

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

249

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.

250

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

251

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

McKenzie, Valerie

252

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.

253

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.

254

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

255

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

256

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

257

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

258

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 planetÕs health for a few amphibians sample many parts of the environment, their health reßects the combined eÝects of many separate

Wake, David B.

259

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

260

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

261

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

262

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

263

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.

264

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

265

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.

266

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

267

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

268

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.

269

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

270

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

271

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

272

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

273

DISTRIBUTION OF AMPHIBIANS IN TERRESTRIAL HABITAT SURROUNDING WETLANDS  

Microsoft Academic Search

Estimating the distribution of amphibians in terrestrial habitats surrounding wetlands is essential for determining how much habitat is required to maintain viable amphibian populations and how much habitat may be allocated to other land use practices. We apply univariate kernel estimation in a new manner to determine the distribution of amphibians during the non-breeding season. We summarized data from 13

Tracy A. G. Rittenhouse; Raymond D. Semlitsch

2007-01-01

274

The amphibian decline crisis: A watershed for conservation biology?  

Microsoft Academic Search

Amphibians have declined dramatically in many areas of the world. These declines seem to have worsened over the past 25 years and amphibians are now more threatened than either mammals or birds, though comparisons with other taxa are confounded by a shortage of reliable data. Research into amphibian declines has focused on: (1) documentation at the landscape or population level;

Trevor J. C. Beebee; Richard A. Griffiths

2005-01-01

275

Amphibian Population Declines in Latin America: A Synthesis1  

Microsoft Academic Search

The loss of global amphibian biodiversity has been well documented in recent years. The greatest information from Latin America came from countries such as Costa Rica, Panama, Ecuador, and Puerto Rico. The five papers in this special section illustrate the critical status of Latin American amphibians and further demonstrate certain commonalities of amphibian population declines within the region. These studies

Karen R. Lips; Patricia A. Burrowes; Joseph R. Mendelson; Gabriela Parra-Olea

2005-01-01

276

Deciphering amphibian diversity through DNA barcoding: chances and challenges  

E-print Network

Building, Berkeley, CA 94720-3160, USA Amphibians globally are in decline, yet there is still a tremendous. This partly results from the phenomenon of multi- causal global amphibian declines, which in the most alarmingDeciphering amphibian diversity through DNA barcoding: chances and challenges Miguel Vences1

Vieites, David R.

277

SHORT COMMUNICATION A decade of amphibian population genetic studies: synthesis  

E-print Network

+Business Media B.V. 2012 Abstract Amphibians are declining globally, and a comprehensive understanding Conservation Introduction In the face of global amphibian declines, it has become increasingly criticalSHORT COMMUNICATION A decade of amphibian population genetic studies: synthesis and recommendations

Storfer, Andrew

278

Electrolyte depletion and osmotic imbalance in amphibians with chytridiomycosis  

Microsoft Academic Search

Mounting evidence implicates the disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis, in global amphibian declines and extinctions. While the virulence of this disease has been clearly demonstrated, there is, as yet, no mechanistic explanation for how B. dendrobatidis kills amphibians. To investigate the pathology of chytridiomycosis, blood samples were collected from uninfected, aclinically infected and clinically diseased amphibians and

Jamie Voyles; Lee Berger; Sam Young; Rick Speare; Rebecca Webb; Jeffrey Warner; Donna Rudd; Ruth Campbell; Lee F. Skerratt

2007-01-01

279

Forecasting changes in amphibian biodiversity: aiming at a moving target  

Microsoft Academic Search

Amphibian population declines and sudden species' extinctions began to be noted at the beginning of the 1980s. Understanding the causes of the losses is hampered by our poor knowledge of the amphibian fauna in many parts of the world. Amphibian taxa are still being described at a high rate, especially in the tropics, which means that even quantifying species lost

James P. Collins; Tim Halliday

2005-01-01

280

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

281

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

282

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.

Northern Prairie Wildlife Research Center.

1997-01-01

283

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

284

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

285

Origin of the Amphibian Chytrid Fungus  

PubMed Central

The sudden appearance of chytridiomycosis, the cause of amphibian deaths and population declines in several continents, suggests that its etiologic agent, the amphibian chytrid Batrachochytrium dendrobatidis, was introduced into the affected regions. However, the origin of this virulent pathogen is unknown. A survey was conducted of 697 archived specimens of 3 species of Xenopus collected from 1879 to 1999 in southern Africa in which the histologic features of the interdigital webbing were analyzed. The earliest case of chytridiomycosis found was in a Xenopus laevis frog in 1938, and overall prevalence was 2.7%. The prevalence showed no significant differences between species, regions, season, or time period. Chytridiomycosis was a stable endemic infection in southern Africa for 23 years before any positive specimen was found outside Africa. We propose that Africa is the origin of the amphibian chytrid and that the international trade in X. laevis that began in the mid-1930s was the means of dissemination. PMID:15663845

du Preez, Louis H.; Hyatt, Alex D.; Muller, Reinhold; Speare, Rick

2004-01-01

286

Origin of the amphibian chytrid fungus.  

PubMed

The sudden appearance of chytridiomycosis, the cause of amphibian deaths and population declines in several continents, suggests that its etiologic agent, the amphibian chytrid Batrachochytrium dendrobatidis, was introduced into the affected regions. However, the origin of this virulent pathogen is unknown. A survey was conducted of 697 archived specimens of 3 species of Xenopus collected from 1879 to 1999 in southern Africa in which the histologic features of the interdigital webbing were analyzed. The earliest case of chytridiomycosis found was in a Xenopus laevis frog in 1938, and overall prevalence was 2.7%. The prevalence showed no significant differences between species, regions, season, or time period. Chytridiomycosis was a stable endemic infection in southern Africa for 23 years before any positive specimen was found outside Africa. We propose that Africa is the origin of the amphibian chytrid and that the international trade in X. laevis that began in the mid-1930s was the means of dissemination. PMID:15663845

Weldon, Ché; du Preez, Louis H; Hyatt, Alex D; Muller, Reinhold; Spears, Rick

2004-12-01

287

Microbiota and Mucosal Immunity in Amphibians  

PubMed Central

We know that animals live in a world dominated by bacteria. In the last 20?years, we have learned that microbes are essential regulators of mucosal immunity. Bacteria, archeas, and viruses influence different aspects of mucosal development and function. Yet, the literature mainly covers findings obtained in mammals. In this review, we focus on two major themes that emerge from the comparative analysis of mammals and amphibians. These themes concern: (i) the structure and functions of lymphoid organs and immune cells in amphibians, with a focus on the gut mucosal immune system; and (ii) the characteristics of the amphibian microbiota and its influence on mucosal immunity. Lastly, we propose to use Xenopus tadpoles as an alternative small-animal model to improve the fundamental knowledge on immunological functions of gut microbiota.

Colombo, Bruno M.; Scalvenzi, Thibault; Benlamara, Sarah; Pollet, Nicolas

2015-01-01

288

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), ...

289

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

290

Heart structure and the ancestry of amphibians  

E-print Network

HEART STRUCTURE AND THE ANCESTRY OF AMPHIBIANS A Thesis By Jerry Lee Putnam Submitted to the Graduate College of tne Texas A8M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE ~Januar . ajor Subject... Zoolo v 1967 HEART STRUCTURE AND THE ANCESTRY OF AMPHIBIANS A Thesis Jerry Lee Putnam Approved as ;o yie and content by: r" , 6& C airman of Committee f Department ember (Me;;. ~er ~Member Memb Mem er Januar 1967 ACKNOW'I' EDGEI', ENT Tne...

Putnam, Jerry Lee

1967-01-01

291

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).

292

Chytrid fungus infections in laboratory and introduced Xenopus laevis populations: assessing the risks for U.K. native amphibians  

PubMed Central

The chytrid fungus Batrachochytrium dendrobatidis (Bd) is notorious amongst current conservation biology challenges, responsible for mass mortality and extinction of amphibian species. World trade in amphibians is implicated in global dissemination. Exports of South African Xenopus laevis have led to establishment of this invasive species on four continents. Bd naturally infects this host in Africa and now occurs in several introduced populations. However, no previous studies have investigated transfer of infection into co-occurring native amphibian faunas. A survey of 27 U.K. institutions maintaining X. laevis for research showed that most laboratories have low-level infection, a risk for native species if animals are released into the wild. RT-PCR assays showed Bd in two introduced U.K. populations of X. laevis, in Wales and Lincolnshire. Laboratory and field studies demonstrated that infection levels increase with stress, especially low temperature. In the U.K., native amphibians may be exposed to intense transmission in spring when they enter ponds to spawn alongside X. laevis that have cold-elevated Bd infections. Exposure to cross-infection has probably been recurrent since the introduction of X. laevis, >20 years in Lincolnshire and 50 years in Wales. These sites provide an important test for assessing the impact of X. laevis on Bd spread. However, RT-PCR assays on 174 native amphibians (Bufo, Rana, Lissotriton and Triturus spp.), sympatric with the Bd-infected introduced populations, showed no foci of self-sustaining Bd transmission associated with X. laevis. The abundance of these native amphibians suggested no significant negative population-level effect after the decades of co-occurrence. PMID:25843959

Tinsley, Richard C.; Coxhead, Peter G.; Stott, Lucy C.; Tinsley, Matthew C.; Piccinni, Maya Z.; Guille, Matthew J.

2015-01-01

293

Acute and chronic effects of carbaryl on survival, growth, and metamorphosis in the bullfrog ( Rana tigrina )  

Microsoft Academic Search

The effects of carbaryl (1-naphthalenyl methylcarbamate), an extensively used insecticide in agricultural operations, have been studied on survival, growth, and metamorphosis of the bullfrog tadpoleRana tigrina. The 96 hr LC50 value for tadpoles (0.02 g) was 6.2 mg\\/L. The tadpoles were reared from hatching to metamorphosis in sublethal concentrations of carbaryl. Rates of feeding, defecation, and excretion increased with increasing

M. Peter Marian; V. Arul; T. J. Pandian

1983-01-01

294

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

295

The role of amphibian antimicrobial peptides in protection of amphibians from pathogens linked to global amphibian declines  

Microsoft Academic Search

Amphibian species have experienced population declines and extinctions worldwide that are unprecedented in recent history. Many of these recent declines have been linked to a pathogenic skin fungus, Batrachochytrium dendrobatidis, or to iridoviruses of the genus Ranavirus. One of the first lines of defense against pathogens that enter by way of the skin are antimicrobial peptides synthesized and stored in

Louise A. Rollins-Smith

2009-01-01

296

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

297

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

298

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

299

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

300

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

301

Amphibian pathogens in Southeast Asian frog trade.  

PubMed

Amphibian trade is known to facilitate the geographic spread of pathogens. Here we assess the health of amphibians traded in Southeast Asia for food or as pets, focusing on Batrachochytrium dendrobatidis (Bd), ranavirus and general clinical condition. Samples were collected from 2,389 individual animals at 51 sites in Lao PDR, Cambodia, Vietnam and Singapore for Bd screening, and 74 animals in Cambodia and Vietnam for ranavirus screening. Bd was found in one frog (n = 347) in Cambodia and 13 in Singapore (n = 419). No Bd was found in Lao PDR (n = 1,126) or Vietnam (n = 497), and no ranavirus was found in Cambodia (n = 70) or Vietnam (n = 4). Mild to severe dermatological lesions were observed in all East Asian bullfrogs Hoplobatrachus rugolosus (n = 497) sampled in farms in Vietnam. Histologic lesions consistent with sepsis were found within the lesions of three frogs and bacterial sepsis in two (n = 4); one had Gram-negative bacilli and one had acid-fast organisms consistent with mycobacterium sp. These results confirm that Bd is currently rare in amphibian trade in Southeast Asia. The presence of Mycobacterium-associated disease in farmed H. rugolosus is a cause for concern, as it may have public health implications and indicates the need for improved biosecurity in amphibian farming and trade. PMID:23404036

Gilbert, Martin; Bickford, David; Clark, Leanne; Johnson, Arlyne; Joyner, Priscilla H; Ogg Keatts, Lucy; Khammavong, Kongsy; Nguy?n V?n, Long; Newton, Alisa; Seow, Tiffany P W; Roberton, Scott; Silithammavong, Soubanh; Singhalath, Sinpakhone; Yang, Angela; Seimon, Tracie A

2012-12-01

302

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!

2012-11-14

303

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

304

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

305

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

306

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

307

Endemic Infection of the Amphibian Chytrid Fungus  

E-print Network

Endemic Infection of the Amphibian Chytrid Fungus in a Frog Community Post-Decline Richard W. R University, Townsville, Queensland, Australia The chytrid fungus Batrachochytrium dendrobatidis has been collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus

308

Amphibian Declines in Brazil: An Overview1  

Microsoft Academic Search

Population declines have previously been reported for at least 31 amphibian species in Brazil, in the families Leptodactylidae (19), Hylidae (7), Centrolenidae (2), Dendrobatidae (2), and Bufonidae (1). In five Brazilian museum collections, we found no entries of new records dating back to at least 15 yr ago for 13 of these species. We suggest that these taxa be studied

Paula Cabral Eterovick; Ana Carolina Oliveira de Queiroz Carnaval; Diva Maria Borges-Nojosa; Debora Leite Silvano; Magno Vicente Segalla; Ivan Sazima

2005-01-01

309

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

310

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.

311

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

312

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...

313

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

314

Meeting ultraviolet B radiation requirements of amphibians in captivity: A case study with mountain chicken frogs (Leptodactylus fallax) and general recommendations for pre-release health screening.  

PubMed

Conservation breeding programmes are a tool used to prevent amphibian extinctions. The husbandry requirements of amphibians are complex. Ongoing research is needed to ensure optimal management of those captive-bred animals destined, in particular, for reintroduction. The UV-B and vitamin D3 requirements of amphibians are largely unknown. Metabolic bone disease has been reported in a number of species. These include the Critically Endangered mountain chicken frog (Leptodactylus fallax) reared in captivity on diets supplemented with a high-calcium multivitamin and mineral supplement containing vitamin D3 but without UV-B provision. Captive-bred L. fallax being reared for reintroduction to Montserrat were provided with UV-B radiation from metamorphosis and were fed on insects supplemented with vitamins and minerals. Overlapping heat, light and UV-B gradients were provided, mimicking what we believe best represents the natural situation and thereby facilitated self-regulation of UV-B exposure. A subset of 10 frogs was periodically radiographed to assess skeletal health. Radiographic bone density and anatomical integrity appeared unremarkable when compared with a wild caught L. fallax. In addition to other routine health-screening, we recommend that radiography be performed to a structured schedule on a subset of all captive-bred and reared amphibians to assess skeletal health and to gauge the appropriateness of captive husbandry. We demonstrate here that, through the appropriate provision of a combination of both UV-B radiation and dietary supplementation, L. fallax can be bred and reared in captivity with healthy skeletal development. Zoo Biol. 34:46-52, 2015. © 2014 Wiley Periodicals Inc. PMID:25255994

Tapley, Benjamin; Rendle, Matthew; Baines, Frances M; Goetz, Matthias; Bradfield, Kay S; Rood, David; Lopez, Javier; Garcia, Gerardo; Routh, Andrew

2015-01-01

315

Vestibular Lesion-Induced Developmental Plasticity in Spinal Locomotor Networks during Xenopus laevis Metamorphosis  

PubMed Central

During frog metamorphosis, the vestibular sensory system remains unchanged, while spinal motor networks undergo a massive restructuring associated with the transition from the larval to adult biomechanical system. We investigated in Xenopus laevis the impact of a pre- (tadpole stage) or post-metamorphosis (juvenile stage) unilateral labyrinthectomy (UL) on young adult swimming performance and underlying spinal locomotor circuitry. The acute disruptive effects on locomotion were similar in both tadpoles and juvenile frogs. However, animals that had metamorphosed with a preceding UL expressed restored swimming behavior at the juvenile stage, whereas animals lesioned after metamorphosis never recovered. Whilst kinematic and electrophysiological analyses of the propulsive system showed no significant differences in either juvenile group, a 3D biomechanical simulation suggested that an asymmetry in the dynamic control of posture during swimming could account for the behavioral restoration observed in animals that had been labyrinthectomized before metamorphosis. This hypothesis was subsequently supported by in vivo electromyography during free swimming and in vitro recordings from isolated brainstem/spinal cord preparations. Specifically, animals lesioned prior to metamorphosis at the larval stage exhibited an asymmetrical propulsion/posture coupling as a post-metamorphic young adult. This developmental alteration was accompanied by an ipsilesional decrease in propriospinal coordination that is normally established in strict left-right symmetry during metamorphosis in order to synchronize dorsal trunk muscle contractions with bilateral hindlimb extensions in the swimming adult. Our data thus suggest that a disequilibrium in descending vestibulospinal information during Xenopus metamorphosis leads to an altered assembly of adult spinal locomotor circuitry. This in turn enables an adaptive compensation for the dynamic postural asymmetry induced by the vestibular imbalance and the restoration of functionally-effective behavior. PMID:23951071

Beyeler, Anna; Rao, Guillaume; Ladepeche, Laurent; Jacques, André; Simmers, John; Le Ray, Didier

2013-01-01

316

Vestibular lesion-induced developmental plasticity in spinal locomotor networks during Xenopus laevis metamorphosis.  

PubMed

During frog metamorphosis, the vestibular sensory system remains unchanged, while spinal motor networks undergo a massive restructuring associated with the transition from the larval to adult biomechanical system. We investigated in Xenopus laevis the impact of a pre- (tadpole stage) or post-metamorphosis (juvenile stage) unilateral labyrinthectomy (UL) on young adult swimming performance and underlying spinal locomotor circuitry. The acute disruptive effects on locomotion were similar in both tadpoles and juvenile frogs. However, animals that had metamorphosed with a preceding UL expressed restored swimming behavior at the juvenile stage, whereas animals lesioned after metamorphosis never recovered. Whilst kinematic and electrophysiological analyses of the propulsive system showed no significant differences in either juvenile group, a 3D biomechanical simulation suggested that an asymmetry in the dynamic control of posture during swimming could account for the behavioral restoration observed in animals that had been labyrinthectomized before metamorphosis. This hypothesis was subsequently supported by in vivo electromyography during free swimming and in vitro recordings from isolated brainstem/spinal cord preparations. Specifically, animals lesioned prior to metamorphosis at the larval stage exhibited an asymmetrical propulsion/posture coupling as a post-metamorphic young adult. This developmental alteration was accompanied by an ipsilesional decrease in propriospinal coordination that is normally established in strict left-right symmetry during metamorphosis in order to synchronize dorsal trunk muscle contractions with bilateral hindlimb extensions in the swimming adult. Our data thus suggest that a disequilibrium in descending vestibulospinal information during Xenopus metamorphosis leads to an altered assembly of adult spinal locomotor circuitry. This in turn enables an adaptive compensation for the dynamic postural asymmetry induced by the vestibular imbalance and the restoration of functionally-effective behavior. PMID:23951071

Beyeler, Anna; Rao, Guillaume; Ladepeche, Laurent; Jacques, André; Simmers, John; Le Ray, Didier

2013-01-01

317

Orchestrating change: The thyroid hormones and GI-tract development in flatfish metamorphosis.  

PubMed

Metamorphosis in flatfish (Pleuronectiformes) is a late post-embryonic developmental event that prepares the organism for the larval-to-juvenile transition. Thyroid hormones (THs) play a central role in flatfish metamorphosis and the basic elements that constitute the thyroid axis in vertebrates are all present at this stage. The advantage of using flatfish to study the larval-to-juvenile transition is the profound change in external morphology that accompanies metamorphosis making it easy to track progression to climax. This important lifecycle transition is underpinned by molecular, cellular, structural and functional modifications of organs and tissues that prepare larvae for a successful transition to the adult habitat and lifestyle. Understanding the role of THs in the maturation of organs and tissues with diverse functions during metamorphosis is a major challenge. The change in diet that accompanies the transition from a pelagic larvae to a benthic juvenile in flatfish is associated with structural and functional modifications in the gastrointestinal tract (GI-tract). The present review will focus on the maturation of the GI-tract during metamorphosis giving particular attention to organogenesis of the stomach a TH triggered event. Gene transcripts and biological processes that are associated with GI-tract maturation during Atlantic halibut metamorphosis are identified. Gene ontology analysis reveals core biological functions and putative TH-responsive genes that underpin TH-driven metamorphosis of the GI-tract in Atlantic halibut. Deciphering the specific role remains a challenge. Recent advances in characterizing the molecular, structural and functional modifications that accompany the appearance of a functional stomach in Atlantic halibut are considered and future research challenges identified. PMID:24975541

Gomes, A S; Alves, R N; Rønnestad, I; Power, D M

2014-06-26

318

Cost efficiency in the detection of chytridiomycosis using PCR assay  

Microsoft Academic Search

Chytridiomycosis is an emerging infectious disease of amphibians associated with mass mortalities and population declines worldwide. Recent technological advances have resulted in a highly sensitive, non-invasive technique for diagnosing the disease based on a quantitative (real- time) polymerase chain reaction (qPCR) assay. The qPCR assay yields the most accurate and infor- mative data of any available detection technique. However, due

Kerry M. Kriger; Jean-Marc Hero; Kevin J. Ashton

2006-01-01

319

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

320

Metamorphosis of a Butterfly-Associated Bacterial Community  

PubMed Central

Butterflies are charismatic insects that have long been a focus of biological research. They are also habitats for microorganisms, yet these microbial symbionts are little-studied, despite their likely importance to butterfly ecology and evolution. In particular, the diversity and composition of the microbial communities inhabiting adult butterflies remain uncharacterized, and it is unknown how the larval (caterpillar) and adult microbiota compare. To address these knowledge gaps, we used Illumina sequencing of 16S rRNA genes from internal bacterial communities associated with multiple life stages of the neotropical butterfly Heliconius erato. We found that the leaf-chewing larvae and nectar- and pollen-feeding adults of H. erato contain markedly distinct bacterial communities, a pattern presumably rooted in their distinct diets. Larvae and adult butterflies host relatively small and similar numbers of bacterial phylotypes, but few are common to both stages. The larval microbiota clearly simplifies and reorganizes during metamorphosis; thus, structural changes in a butterfly's bacterial community parallel those in its own morphology. We furthermore identify specific bacterial taxa that may mediate larval and adult feeding biology in Heliconius and other butterflies. Although male and female Heliconius adults differ in reproductive physiology and degree of pollen feeding, bacterial communities associated with H. erato are not sexually dimorphic. Lastly, we show that captive and wild individuals host different microbiota, a finding that may have important implications for the relevance of experimental studies using captive butterflies. PMID:24466308

Hammer, Tobin J.; McMillan, W. Owen; Fierer, Noah

2014-01-01

321

Effects of chemical cues on larval survival, settlement and metamorphosis of abalone Haliotis asinina  

NASA Astrophysics Data System (ADS)

Low larval survival, poor settlement, and abnormal metamorphosis are major problems in seed production of donkey-ear abalone Haliotis asinina. We examined the effects of chemical cues including epinephrine, nor-epinephrine, and serotonin on larval survival, settlement, and metamorphosis in order to determine the possibility of using these chemicals to induce the problems. The results show that epinephrine could enhance metamorphosis rate at 10-6 mol/L only but higher concentrations (10-3-10-4 mol/L); and nor-epinephrine could inhibit the performance significantly, and serotonin could increase significantly the performance at a wide-range concentration (10-3-10-6 mol/L). Treatment with serotonin at 10-5 mol/L for 72 hours resulted in the highest settlement rate (42.2%) and survival rate (49.3%), while at 10-4 mol/L for 72 hours resulted in the highest metamorphosis rate (38.8%). Therefore, serotonin may be used as a fast metamorphosis inducer in abalone culture.

Wang, Xiaobing; Bai, Yang; Huang, Bo

2010-11-01

322

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

323

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

324

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

325

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

326

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

327

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, Tropical Medicine and Rehabilitation Sciences, Amphibian Disease Ecology Group, James Cook University The fungus Batrachochytrium dendrobatidis (Bd ) causes a lethal skin disease of amphibians, chytridiomycosis

Rosenblum, Erica Bree

328

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.

329

Distribution of amphibians in terrestrial habitat surrounding wetlands  

Microsoft Academic Search

Estimating the distribution of amphibians in terrestrial habitats surrounding wetlands is essential for determining how much\\u000a habitat is required to maintain viable amphibian populations and how much habitat may be allocated to other land use practices.\\u000a We apply univariate kernel estimation in a new manner to determine the distribution of amphibians during the non-breeding\\u000a season. We summarized data from 13

Tracy A. G. Rittenhouse; Raymond D. Semlitsch

2007-01-01

330

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

331

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

332

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.

333

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

334

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

335

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

336

[Modulating effect of weak combined magnetic fields on duration of mealworm beetle Tenebrio molitor metamorphosis stage].  

PubMed

It is shown that an exposure of pupae of the mealworm beetle Tenebrio molitor to the combined static (42 ?T) and very weak alternating (250 nT) magnetic fields exerts different influence, depending on the frequency of the alternating magnetic field, on duration of metamorphosis processes in these insects. For instance, an exposure of pupae to weak combined magnetic fields, adjusted to the frequency of ion cyclotron resonance for glutaminic acid (4,4 Hz), stimulates metamorphosis process--a transitional stage from pupae to imago lasts shorter. An inhibiting effect was observed when adjusted to the frequency of ion cyclotron resonance for Ca2 (32,2 Hz). At some frequencies this effect is not seen. For instance, an exposure at a frequency of ion cyclotron resonance for K+ (16,5 Hz) exerts no noticeable effect on the duration of the pupal metamorphosis stage. PMID:25715625

Novikov, V V; She?man, I M; Iablokova, E V; Fesenko, E E

2014-01-01

337

The effect of pinealectomy, continuous light, and continuous darkness on metamorphosis of anadromous sea lampreys, Petromyzon marinus L  

SciTech Connect

The role of the pineal complex in lamprey metamorphosis was investigated by examining the influence of pinealectomy and continuous light and darkness on the initiation of this event in anadromous sea lampreys, Petromyzon marinus L. Larval lampreys, which on the basis of a condition factor were considered likely to enter metamorphosis in July, were separated in May of 1979 and 1980 into the following groups: (1) intact controls, (2) sham-operated controls, (3) pinealectomized individuals, (4) those exposed to continuous light, and (5) those exposed to continuous light or dark. The importance of the pineal complex to metamorphosis was supported by morphological evidence that, in all presumably pinealectomized individuals that entered metamorphosis, the complex had apparently not been removed during the surgical procedure. The ways in which the pineal complex may be involved in lamprey metamorphosis are discussed.

Cole, W.C.; Youson, J.H.

1981-12-01

338

Xenopus laevis Müllerian ducts are sensitive indicators of estrogenic or androgenic chemical exposure in vivo (poster presentation)  

EPA Science Inventory

The Larval Amphibian Growth and Development Assay (LAGDA) is one of a series of Tier 2 test guidelines developed by the US EPA under the Endocrine Disruptor Screening Program. The LAGDA was designed to evaluate effects on growth, thyroid-mediated amphibian metamorphosis and repr...

339

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

340

Regulation of Drosophila metamorphosis by xenobiotic response regulators.  

PubMed

Mammalian Nrf2-Keap1 and the homologous Drosophila CncC-dKeap1 protein complexes regulate both transcriptional responses to xenobiotic compounds as well as native cellular and developmental processes. The relationships between the functions of these proteins in xenobiotic responses and in development were unknown. We investigated the genes regulated by CncC and dKeap1 during development and the signal transduction pathways that modulate their functions. CncC and dKeap1 were enriched within the nuclei in many tissues, in contrast to the reported cytoplasmic localization of Keap1 and Nrf2 in cultured mammalian cells. CncC and dKeap1 occupied ecdysone-regulated early puffs on polytene chromosomes. Depletion of either CncC or dKeap1 in salivary glands selectively reduced early puff gene transcription. CncC and dKeap1 depletion in the prothoracic gland as well as cncC(K6/K6) and dKeap1(EY5/EY5) loss of function mutations in embryos reduced ecdysone-biosynthetic gene transcription. In contrast, dKeap1 depletion and the dKeap1(EY5/EY5) loss of function mutation enhanced xenobiotic response gene transcription in larvae and embryos, respectively. Depletion of CncC or dKeap1 in the prothoracic gland delayed pupation by decreasing larval ecdysteroid levels. CncC depletion suppressed the premature pupation and developmental arrest caused by constitutive Ras signaling in the prothoracic gland; conversely, constitutive Ras signaling altered the loci occupied by CncC on polytene chromosomes and activated transcription of genes at these loci. The effects of CncC and dKeap1 on both ecdysone-biosynthetic and ecdysone-regulated gene transcription, and the roles of CncC in Ras signaling in the prothoracic gland, establish the functions of these proteins in the neuroendocrine axis that coordinates insect metamorphosis. PMID:23408904

Deng, Huai; Kerppola, Tom K

2013-01-01

341

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

342

Phosphoproteome analysis during larval development and metamorphosis in the spionid polychaete Pseudopolydora vexillosa  

PubMed Central

Background The metamorphosis of the spionid polychaete Pseudopolydora vexillosa includes spontaneous settlement onto soft-bottom habitats and morphogenesis that can be completed in a very short time. A previous study on the total changes to the proteome during the various developmental stages of P. vexillosa suggested that little or no de novo protein synthesis occurs during metamorphosis. In this study, we used multicolor fluorescence detection of proteins in 2-D gels for differential analysis of proteins and phosphoproteins to reveal the dynamics of post-translational modification proteins in this species. A combination of affinity chromatography, 2D-PAGE, and mass spectrometry was used to identify the phosphoproteins in pre-competent larvae, competent larvae, and newly metamorphosed juveniles. Results We reproducibly detected 210, 492, and 172 phosphoproteins in pre-competent larvae, competent larvae, and newly metamorphosed juveniles, respectively. The highest percentage of phosphorylation was observed during the competent larval stage. About 64 stage-specific phosphoprotein spots were detected in the competent stage, and 32 phosphoproteins were found to be significantly differentially expressed in the three stages. We identified 38 phosphoproteins, 10 of which were differentially expressed during metamorphosis. These phosphoproteins belonged to six categories of biological processes: (1) development, (2) cell differentiation and integrity, (3) transcription and translation, (4) metabolism, (5) protein-protein interaction and proteolysis, and (6) receptors and enzymes. Conclusion This is the first study to report changes in phosphoprotein expression patterns during the metamorphosis of the marine polychaete P. vexillosa. The higher degree of phosphorylation during the process of attaining competence to settle and metamorphose may be due to fast morphological transitions regulated by various mechanisms. Our data are consistent with previous studies showing a high percentage of phosphorylation during competency in the barnacle Balanus amphitrite and the bryozoan Bugula neritina. The identified phosphoproteins may play an important role during metamorphosis, and further studies on the location and functions of important proteins during metamorphosis are warranted. PMID:21612608

2011-01-01

343

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

344

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

345

First survey for the amphibian chytrid fungus Batrachochytrium dendrobatidis in Connecticut (USA) finds widespread prevalence.  

PubMed

The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is an emerging infectious fungal pathogen of amphibians and is linked to global population declines. Until now, there has only been 1 survey for the fungus in the northeastern USA, which focused primarily on northern New England. We tested for Bd in a large number of samples (916 individuals from 116 sites) collected throughout the state of Connecticut, representing 18 native amphibian species. In addition, 239 preserved wood frog Lithobates sylvaticus tadpoles from throughout the state were screened for the fungus. Bd presence was assessed in both the fresh field swabs and the preserved samples using a sensitive quantitative PCR assay. Our contemporary survey found widespread Bd prevalence throughout Connecticut, occurring in 14 species and in 28% of all sampled animals. No preserved L. sylvaticus specimens tested positive for the fungus. Two common species, bullfrogs R. catesbeiana and green frogs R. clamitans had particularly high infection rates (0.21-0.39 and 0.33-0.42, respectively), and given their wide distribution throughout the state, we suggest they may serve as sentinels for Bd occurrence in this region. Further analyses found that several other factors increase the likelihood of infection, including life stage, host sex, and host family. Within sites, ponds with ranids, especially green frogs, increased the likelihood of Bd prevalence. By studying Bd in populations not facing mass declines, the results from this study are an important contribution to our understanding of how some amphibian species and populations remain infected yet exhibit no signs of chytridiomycosis even when Bd is widely distributed. PMID:23446966

Richards-Hrdlicka, Kathryn L; Richardson, Jonathan L; Mohabir, Leon

2013-02-28

346

Induction of larval settlement and metamorphosis of Haliotis discus hannai Ino (Gastropoda, Mollusca)  

NASA Astrophysics Data System (ADS)

Conspecific foot mucus, excessive [K+] and gamma-aminobutyric acid (GABA) showed different metamorphosis-inductive effect on the veliger of Haliotis discus hannai. The inductive effect of excessive [K+] and GABA was developmental stage-dependent and dose-dependent, while that of conspecific foot mucus was only developmental stage-dependent. At 20°C the veliger larvae became competent within 4 days after fertilization. H. discus hannai larvae showed gregarious settlement pattern on the conspecific foot mucus under the conditions of either presence or absence of KCl or GABA. The present studies showed that the effect of conspecific foot mucus on abalone larvae metamorphosis could be dose-independent.

Yang, Yu; Wu, Bao-Ling

1995-03-01

347

Global rates of habitat loss and implications for amphibian conservation  

USGS Publications Warehouse

A large number of factors are known to affect amphibian population viability, but most authors agree that the principal causes of amphibian declines are habitat loss, alteration, and fragmentation. We provide a global assessment of land use dynamics in the context of amphibian distributions. We accomplished this by compiling global maps of amphibian species richness and recent rates of change in land cover, land use, and human population growth. The amphibian map was developed using a combination of published literature and digital databases. We used an ecoregion framework to help interpret species distributions across environmental, rather than political, boundaries. We mapped rates of land cover and use change with statistics from the World Resources Institute, refined with a global digital dataset on land cover derived from satellite data. Temporal maps of human population were developed from the World Resources Institute database and other published sources. Our resultant map of amphibian species richness illustrates that amphibians are distributed in an uneven pattern around the globe, preferring terrestrial and freshwater habitats in ecoregions that are warm and moist. Spatiotemporal patterns of human population show that, prior to the 20th century, population growth and spread was slower, most extensive in the temperate ecoregions, and largely exclusive of major regions of high amphibian richness. Since the beginning of the 20th century, human population growth has been exponential and has occurred largely in the subtropical and tropical ecoregions favored by amphibians. Population growth has been accompanied by broad-scale changes in land cover and land use, typically in support of agriculture. We merged information on land cover, land use, and human population growth to generate a composite map showing the rates at which humans have been changing the world. When compared with the map of amphibian species richness, we found that many of the regions of the earth supporting the richest assemblages of amphibians are currently undergoing the highest rates of landscape modification. ?? 2007 by the American Society of Ichthyologists and Herpetologists.

Gallant, A.L.; Klaver, R.W.; Casper, G.S.; Lannoo, M.J.

2007-01-01

348

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

349

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

350

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

351

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

352

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

353

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

354

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

355

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

356

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

357

Deciphering amphibian diversity through DNA barcoding: chances and challenges  

Microsoft Academic Search

Amphibians globally are in decline, yet there is still a tremendous amount of unrecognized diversity, calling for an acceleration of taxonomic exploration. This process will be greatly facilitated by a DNA barcoding system; however, the mitochondrial population structure of many amphibian species presents numerous challenges to such a standardized, single locus, approach. Here we analyse intra- and interspecific patterns of

Miguel Vences; Meike Thomas; Ronald M. Bonett; D. Rodriguez Vieites

2005-01-01

358

Phonotaxis to Amphibian Vocalizations in Culex territans (Diptera: Culicidae)  

Microsoft Academic Search

Culexterritans Walker (Diptera: Culicidae) acquires bloodmeals from amphibian hosts. Females overwinter as inseminated adults and exit diapause in New Jersey when spring peepers (Pseudacris crucifer) are calling. We tested the hypothesis that Cx. territans uses amphibian vocal- izations as a long-distance attractant. Two thirds of females oriented toward sound across all exper- iments. Females allowed to orient toward or away

Kristen Bartlett-Healy; Wayne Crans; Randy Gaugler

2008-01-01

359

Selected Infectious Diseases of Wild Reptiles and Amphibians  

Microsoft Academic Search

Infectious diseases have caused a decline in captive and wild populations of reptiles and amphibians. Contributing factors for the decline of wild populations, and their increased susceptibility to infectious diseases, include environmental pressures, such as loss or decline of habitat, exposure to pollutants, and translocation into new habitats. Reptiles and amphibians are often exposed to new pathogens after collection from

Juergen Schumacher

2006-01-01

360

Impacts of cattle on amphibian larvae and the aquatic environment  

Microsoft Academic Search

SUMMARY 1. Agricultural practices such as cattle farming may have direct or indirect negative effects on larval amphibians by decreasing water quality through deposition of nitrogenous waste, causing eutrophication, and grazing shoreline vegetation that contributes to detrital cover and food. 2. We sampled amphibian larvae on the Cumberland Plateau, Tennessee, U.S.A., twice per week, water quality twice per month and

A. C HANDLER; M ATTHEW; J. G RAY; E LIZABETH C. B URTON; DEBRA L. M ILLER

2008-01-01

361

Population differentiation of temperate amphibians in unpredictable environments  

Microsoft Academic Search

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

LAUREN M. CHAN; KELLY R. ZAMUDIO

2009-01-01

362

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...

363

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...

364

Amphibian Declines and Environmental Change in the Eastern Mojave Desert  

Microsoft Academic Search

Eight amphibian taxa historically inhabited sparsely distributed wetlands in the Mojave Desert of western North America, habitats that have been dramatically altered or eliminated as a result of human activities. Changes in the distributions of these and two introduced amphibians, and associated environmental changes, are evaluated herein for an approximately 20,000 km2 area in the eastern Mojave Desert. Striking changes

David F. Bradford

365

Hearing and Sound Communication in Amphibians: Prologue and Prognostication  

Microsoft Academic Search

1. Prologue The vertebrate class Amphibia is composed of three orders: the Gymnophiona (caecilians) or legless amphibians (not known to vocalize), the Urodela (salamanders and newts), and the Anura (frogs and toads). With few exceptions, anuran amphibians are the most highly vocal of the amphibia, although the Pacific giant salamander (Dicamptodon tenebrous) is among a small group of urodeles known

Peter M. Narins; Albert S. Feng

366

Current and Future Effects of Climate Change on Montane Amphibians  

NASA Astrophysics Data System (ADS)

Breeding phenology of amphibians in inextricably linked to weather, and change in the timing of breeding resulting from climate change may have consequences for the fitness of individuals and may affect persistence of amphibian populations. Amphibians in some north temperate locations have been observed to breed earlier in recent years in response to warmer spring temperatures, but this is not a universal phenomenon. In mountain populations, phenology is influenced by snow deposition as much as temperature. A trend towards earlier breeding, associated with increasing El Niño frequency, may be occurring in the Cascade Mountains in Oregon, but only at lower elevations. There is no evidence for changes in the dates of breeding activity by amphibians in the Rocky Mountains. Too few amphibian species have been studied, and those for which data exist have been studied for too brief a span of years to allow general conclusions about the effects of climate change. However, regardless of whether climate change has contributed to current amphibian declines, changes in temperature and the extent and duration of snow cover predicted for the next century will have increasingly severe consequences for the persistence of some species. Additional observations from amphibian populations, and spatial and temporal modeling of climate variables are needed to generate predictions of past and future breeding phenology, and the effects on amphibian population dynamics.

Corn, S.

2002-05-01

367

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

368

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

369

Ultraviolet radiation, toxic chemicals and amphibian population declines  

Microsoft Academic Search

As part of an overall 'biodiversity crisis', many amphibian populations are in decline throughout the world. Numerous factors have contributed to these declines, including habitat destruction, pathogens, increasing ultraviolet (UV) radiation, introduced non-native species and contaminants. In this paper we review the contribution of increasing UV radiation and environmental contamination to the global decline of amphibian populations. Both UV radiation

Andrew R. Blaustein; John M. Romansic; Joseph M. Kiesecker; Audrey C. Hatch

2003-01-01

370

Chytrid fungi and amphibian declines: Overview implications and future directions  

Microsoft Academic Search

ABSTRACT A recently described chytrid fungus, genus Batrachochytrium, killed free-living and captive amphibians in Australia, Central America and the USA. There is epidemiological, pathological, and experimental evidence that some amphibian populations suddenly declined due to mass mortalities caused by chytridiomycosis. These were notably high altitude, stream dwelling rainforest anurans in protected areas of Queensland and Panama. Chytrid fungi caused a

Lee Berger; Rick Speare; Alex Hyatt

371

Measuring the Meltdown: Drivers of Global Amphibian Extinction and Decline  

Microsoft Academic Search

Habitat loss, climate change, over-exploitation, disease and other factors have been hypothesised in the global decline 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 (2,583 species) to quantify the influences of life history, climate, human density and habitat loss

Navjot S. Sodhi; David Bickford; Arvin C. Diesmos; Tien Ming Lee; Lian Pin Koh; Barry W. Brook; Cagan H. Sekercioglu; Corey J. A. Bradshaw

2008-01-01

372

Examining the Evidence for Chytridiomycosis in Threatened Amphibian Species  

Microsoft Academic Search

Extinction risks are increasing for amphibians due to rising threats and minimal conservation efforts. Nearly one quarter of all threatened\\/extinct amphibians in the IUCN Red List is purportedly at risk from the disease chytridiomycosis. However, a closer look at the data reveals that Batrachochytrium dendrobatidis (the causal agent) has been identified and confirmed to cause clinical disease in only 14%

Matthew Heard; Katherine F. Smith; Kelsey Ripp

2011-01-01

373

Amphibian chytridiomycosis: strategies for captive management and conservation  

Microsoft Academic Search

Dramatic declines and extinctions of amphibian species have occurred worldwide over the last three decades owing to the introduction of chytridiomycosis. This em- erging infectious disease is caused by the chytrid fungus Batrachochytrium dendrobatidis, a virulent water-borne pathogen of many amphibian species. It has caused epidemic waves of high mortality as it spread through susceptible wild populations in Australia, North,

S. YOUNG; L. BERGER; R. SPEARE

2007-01-01

374

Late Cretaceous vicariance in Gondwanan amphibians.  

PubMed

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

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

2006-01-01

375

Larval experience and latent effects--metamorphosis is not a new beginning  

E-print Network

of great revolution-- commonly it is a dramatic transition to a new life in a new place in a new body has been completed, often long after it has been completed. In the marine literature at least, it has their metamorphosis beyond a certain age (Pechenik 1985; see also Pechenik and Eyster 1989). But the first evidence

376

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

377

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

378

Energetics of Larval Swimming and Metamorphosis in Four Species of Bugula (Bryozoa)  

Microsoft Academic Search

The amount of energy available to larvae dur- ing swimming, location of a suitable recruitment site, and metamorphosis influences the length of time they can spend in the plankton. Energetic parameters such as swimming speed, oxygen consumption during swimming and meta- morphosis, and elemental carbon and nitrogen content were measured for larvae of four species of bryozoans, Bugula neritina, B.

DEAN E. WENDT

2000-01-01

379

Juvenile hormone resistance gene Methoprene-tolerant controls entry into metamorphosis in the beetle Tribolium castaneum.  

PubMed

Besides being a spectacular developmental process, metamorphosis is key to insect success. Entry into metamorphosis is controlled by juvenile hormone (JH). In larvae, JH prevents pupal and adult morphogenesis, thus keeping the insect in its immature state. How JH signals to preclude metamorphosis is poorly understood, and a JH receptor remains unknown. One candidate for the JH receptor role is the Methoprene-tolerant (Met) Per-Arnt-Sim (PAS) domain protein [also called Resistance to JH, Rst (1)JH], whose loss confers tolerance to JH and its mimic methoprene in the fruit fly Drosophila melanogaster. However, Met deficiency does not affect the larval-pupal transition, possibly because this process does not require JH absence in Drosophila. By contrast, the red flour beetle Tribolium castaneum is sensitive to developmental regulation by JH, thus making an ideal system to examine the role of Met in the antimetamorphic JH action. Here we show that impaired function of the Met ortholog TcMet renders Tribolium resistant to the effects of ectopic JH and, in a striking contrast to Drosophila, causes early-stage beetle larvae to undergo precocious metamorphosis. This is evident as TcMet-deficient larvae pupate prematurely or develop specific heterochronic phenotypes such as pupal-like cuticular structures, appendages, and compound eyes. Our results demonstrate that TcMet functions in JH response and provide the critical evidence that the putative JH receptor Met mediates the antimetamorphic effect of JH. PMID:17537916

Konopova, Barbora; Jindra, Marek

2007-06-19

380

Homeopathically prepared dilution of Rana catesbeiana thyroid glands modifies its rate of metamorphosis  

Microsoft Academic Search

One strand of research on the scientific basis of homeopathy is based on inversion effects of dilutions and the biophysical properties of information transfer. A model developed by Endler, was the basis for the study of the influence of high-diluted solution (1:1026 part by weight) of thyroid glands on the rate of metamorphosis of the frog Rana catesbeiana from the

J. R. P Guedes; C. M Ferreira; H. M. B Guimarães; P. H. N Saldiva; V. L Capelozzi

2004-01-01

381

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.

382

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

383

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, ...

384

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....

385

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.

386

On nitric oxide signaling, metamorphosis, and the evolution of biphasic life cycles  

Microsoft Academic Search

SUMMARY Complex life cycles are ancient and widely distributed, particularly so in the marine environment. Generally, the marine biphasic life cycle consists of pre- reproductive stages that exist in the plankton for various periods of time before settling and transforming into a benthic reproductive stage. Pre-reproductive stages are frequently phenotypically distinct from the reproductive stage, and thelife cycle transition (metamorphosis)

Cory D. Bishop; Bruce P. Brandhorst

2003-01-01

387

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,...

388

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

Microsoft Academic Search

To rear this species in captivity required knowledge of the kinds of organisms it ate. Larvae ate zooplankton (copepods), but prejuveniles and juveniles fed chiefly on phytoplankton. There were similarities as well as dif­ ferences between the alimentary tract contents of the fish and the composition of the plankton community. Changes in food habits during metamorphosis were Laboratory research is

FRED C. JUNEI; FRANK T. CARLSON

389

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

390

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.

391

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

392

Experimental Infection and Repeat Survey Data Indicate the Amphibian Chytrid Batrachochytrium dendrobatidis May Not  

E-print Network

Experimental Infection and Repeat Survey Data Indicate the Amphibian Chytrid Batrachochytrium, Townsville, Queensland 4811, Australia Abstract: Chytridiomycosis is a fatal disease of amphibians, caused by the amphibian chytrid Batrachochytrium dendrobatidis. The disease is unusual in that it may drive many amphibian

Doak, Dan F.

393

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.

394

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.

395

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

396

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

397

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

398

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

399

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

400

Alteration of Larval Development and Metamorphosis by Nitrate and Perchlorate in Southern Leopard Frogs ( Rana sphenocephala )  

Microsoft Academic Search

Amphibians are sensitive to a great variety of agrochemicals. Nitrate compounds are commonly applied as fertilizers, whereas\\u000a perchlorate salts occur as by-products of the military industry and in some nitrate fertilizers. Both compounds are highly\\u000a soluble and can easily diffuse between ground and surface water, thus potentially affecting amphibians. Nitrate reduces embryonic\\u000a and larval survival and development, whereas perchlorate has

Manuel E. Ortiz-Santaliestra; Donald W. Sparling

2007-01-01

401

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

402

Shedding Light on Ultraviolet Radiation and Amphibian Embryos  

NSDL National Science Digital Library

This peer-reviewed article from BioScience journal is about the effects of UV radiation on amphibian population. The hypothesis that increasing ultraviolet-B (UVB) radiation is a causal factor in the decline of amphibian populations has received considerable attention in the scientific and public media. To evaluate the validity of this hypothesis, it is necessary to examine the natural environmental factors and biological traits of amphibians that protect them from UVB radiation. A careful reading of the literature reveals that most published studies on the effects of ambient UVB radiation on amphibian embryos have found no increased mortality. Those few reports that show harmful effects employ experimental methods that do not place enough importance on the natural abiotic and biotic factors that provide UVB protection. In the laboratory, amphibian embryos are resistant to doses of UVB radiation far higher than those they would normally receive from ambient sunlight. The jelly surrounding amphibian eggs absorbs UVB radiation, as revealed by spectral measurements of absorbance; after UVB exposure, embryos with their jelly capsules removed show significantly higher mortality than those with the jelly intact. In light of this and other factors mitigating UVB absorption, the hypothesis that ambient UVB radiation causes amphibian mortality and population declines is without support.

LAWRENCE E. LICHT (; )

2003-06-01

403

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

404

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 ...

405

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

PubMed

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; Niwa, Ryusuke; Kayashima, Yasunari; Hayashi, Yoshiki; Akagi, Kazutaka; Ueda, Hitoshi; Yamakawa-Kobayashi, Kimiko; Kobayashi, Satoru

2015-02-01

406

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

407

Sound Source Perception in Anuran Amphibians  

PubMed Central

Sound source perception refers to the auditory system’s ability to parse incoming sensory information into coherent representations of distinct sound sources in the environment. Such abilities are no doubt key to successful communication in many taxa, but we know little about their function in animal communication systems. For anuran amphibians (frogs and toads), social and reproductive behaviors depend on a listener’s ability to hear and identify sound signals amid high levels of background noise in acoustically cluttered environments. Recent neuroethological studies are revealing how frogs parse these complex acoustic scenes to identify individual calls in noisy breeding choruses. Current evidence highlights some interesting similarities and differences in how the auditory systems of frogs and other vertebrates (most notably birds and mammals) perform auditory scene analysis. PMID:22265243

Bee, Mark A

2012-01-01

408

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

409

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...

410

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...

411

Environmental correlates to amphibian and reptile diversity in Costa Rica  

E-print Network

the amphibians and reptiles of Costa Rica to examine these species diversity components at the regional scale. To accomplish this, existing species lists were compiled from the literature. Additionally, three herpetofaunal surveys were conducted at under surveyed...

Laurencio, David Edelman

2009-05-15

412

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

413

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

414

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...

415

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

416

Trends in amphibian occupancy in the United States  

USGS Publications Warehouse

Though a third of amphibian species worldwide are thought to be imperiled, existing assessments simply categorize extinction risk, providing little information on the rate of population losses. We conducted the first analysis of the rate of change in the probability that amphibians occupy ponds and other comparable habitat features across the United States. We found that overall occupancy by amphibians declined 3.7% annually from 2002 to 2011. Species that are Red-listed by the International Union for Conservation of Nature (IUCN) declined an average of 11.6% annually. All subsets of data examined had a declining trend including species in the IUCN Least Concern category. This analysis suggests that amphibian declines may be more widespread and severe than previously realized.

Adams, Michael J.; Miller, David A.W.; Muths, Erin; Corn, Paul Stephen; Grant, Evan H. Campbell; Bailey, Larissa L.; Fellers, Gary M.; Fisher, Robert N.; Sadinski, Walter J.; Waddle, Hardin; Walls, Susan C.

2013-01-01

417

Amphibian and Reptile Trade in Texas: Current Status and Trends  

E-print Network

International Trade .................................................................... 48 Collection from the Wild ........................................................... 62 Meat Trade... imported to Texas from other countries January 2002 - June 2008. ....................................... 62 21 Wild collected native amphibians and reptiles by rank with season total and number of active collectors by species...

Prestridge, Heather L.

2010-10-12

418

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 ...

419

Hot bodies protect amphibians against chytrid infection in nature  

PubMed Central

Environmental context strongly affects many host-pathogen interactions, but the underlying causes of these effects at the individual level are usually poorly understood. The amphibian chytrid fungus has caused amphibian population declines and extinctions in many parts of the world. Many amphibian species that have declined or have been extirpated by the pathogen in some environments coexist with it in others. Here we show that in three species of rainforest frogs in nature, individuals' probability of infection by the amphibian chytrid fungus was strongly related to their thermal history. Individuals' probability of infection declined rapidly as they spent more time above the pathogen's upper optimum temperature. This relationship can explain population-level patterns of prevalence in nature, and suggests that natural or artificial selection for higher thermal preferences could reduce susceptibility to this pathogen. Similar individual-level insights could improve our understanding of environmental context-dependence in other diseases. PMID:23519020

Rowley, Jodi J. L.; Alford, Ross A.

2013-01-01

420

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

421

Amphibian occurrence and wetland characteristics in the Puget Sound Basin  

Microsoft Academic Search

We studied the pattern of amphibian distributions within 19 wetlands of the Puget Sound Basin in King County, Washington State\\u000a from 1988 through 1991. Amphibian richness was compared to wetland size, vegetation classes, presence of bullfrog and fish\\u000a predators, hydrologic characteristics of water flow, fluctuation, and permanence, and land use. Low velocity flow and low\\u000a fluctuation were correlated with high

Klaus O. Richter; Amanda L. Azous

1995-01-01

422

[On some features of embryonic development and metamorphosis of Aurelia aurita (Cindaria, Scyphozoa)].  

PubMed

Aurelia aurita is a cosmopolite species of scyphomedusae. Its major structural patterns and life cycle are well investigated. This work provides a detailed study on development and structure of the planula in A. aurita until it completes its metamorphosis. Lifetime observations and histological study performed during the settlement and metamorphosis of the planulae demonstrated that the inner manibrium linen of primary polyp (gastroderm) develops from the ectoderm of the planula posterior end. The spatial and temporal dynamics of serotonergic cells from the early embryonic stages until the formation of the primary polyp were studied for the first time. In addition, the distribution oftyrosinated tubulin and neuropeptide RFamide at different stages ofA. aurita development were studied. PMID:23101407

Ma?orova, T D; Kosevich, I A; Melekhova, O P

2012-01-01

423

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

424

Global amphibian declines: perspectives from the United States and beyond  

USGS Publications Warehouse

Over recent decades, amphibians have experienced population declines, extirpations and species-level extinctions at an alarming rate. Numerous potential etiologies for amphibian declines have been postulated including climate and habitat degradation. Other potential anthropogenic causes including overexploitation and the frequent introductions of invasive predatory species have also been blamed for amphibian declines. Still other underlying factors may include infectious diseases caused by the chytrid fungus Batrachochytrium dendrobatidis, pathogenic viruses (Ranavirus), and other agents. It is nearly certain that more than one etiology is to blame for the majority of the global amphibian declines, and that these causal factors include some combination of climatological or physical habitat destabilization and infectious disease, most notably chytridiomycosis. Scientific research efforts are aimed at elucidating these etiologies on local, regional, and global scales that we might better understand and counteract the driving forces behind amphibian declines. Conservation efforts as outlined in the Amphibian Conservation Action Plan of 2005 are also being made to curtail losses and prevent further extinctions wherever possible.

Densmore, Christine L.

2011-01-01

425

Value of artificial habitats for amphibian reproduction in altered landscapes.  

PubMed

Installation and maintenance of stormwater ponds to detain and treat runoff from impervious surfaces is a common method of stormwater control in developed areas. That these ponds capture pollutants, however, is of concern for wildlife species that use the ponds, particularly pond-breeding amphibians. To assess the relative contribution of stormwater ponds to the persistence of amphibian populations in suburban landscapes, we compared amphibian use of stormwater ponds and other available wetlands in suburban and forested watersheds. We surveyed three suburban and three primarily forested first-order watersheds to identify all potential wetlands that might serve as breeding sites for pond-breeding amphibians. We performed call, egg-mass, and larval surveys to measure breeding effort at each wetland in spring and summer 2007 and 2008. In suburban watersheds most (89%) of the wetlands that had breeding activity were either stormwater ponds or otherwise artificial. This pattern was also evident in the forested watersheds, where amphibians were primarily found breeding in wetlands created by past human activity. Late-stage larvae were found only in anthropogenic wetlands in all study areas because the remaining natural wetlands did not hold water long enough for larvae to complete development. Our results suggest that in urban and suburban landscapes with naturally low densities of wetlands, wetlands created by current or historic land uses may be as important to amphibian conservation as natural wetlands or pools and that management strategies directed at urban and suburban landscapes should recognize and incorporate human-created wetlands. PMID:19681986

Brand, Adrianne B; Snodgrass, Joel W

2010-02-01

426

Tropical amphibian populations experience higher disease risk in natural habitats.  

PubMed

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

2011-06-14

427

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

428

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

429

Coding of amplitude modulation in the auditory midbrain of the bullfrog (Rana catesbeiana) across metamorphosis  

Microsoft Academic Search

The functional development of the auditory system across metamorphosis was examined by recording neural activity from the\\u000a torus semicircularis of larval and postmetamorphic bullfrog froglets in response to amplitude-modulated sound. Multiunit activity\\u000a in the torus semicircularis during early larval stages showed significant phase-locking to the envelopes of amplitude-modulated\\u000a noise bursts, up to modulation rates as high as 250?Hz. Beginning at

S. S. Boatright-Horowitz; C. E. Garabedian; K. H. Odabashian; A. M. Simmons

1999-01-01

430

3D Shape Metamorphosis Based on T-spline Level Sets  

Microsoft Academic Search

Summary form only given. We propose a new method for 3D shape metamorphosis, where the in-between objects are constructed by using T-spline scalar functions. The use of T-spline level sets offers several advantages: First, it is convenient to handle complex topology changes without the need of model parameterization. Second, the constructed objects are smooth (C2 in our case). Third, high

Huaiping Yang; B. Jilttler

2007-01-01

431

Changes in the gut microbiome of the sea lamprey during metamorphosis.  

PubMed

Vertebrate metamorphosis is often marked by dramatic morphological and physiological changes of the alimentary tract, along with major shifts in diet following development from larva to adult. Little is known about how these developmental changes impact the gut microbiome of the host organism. The metamorphosis of the sea lamprey (Petromyzon marinus) from a sedentary filter-feeding larva to a free-swimming sanguivorous parasite is characterized by major physiological and morphological changes to all organ systems. The transformation of the alimentary canal includes closure of the larval esophagus and the physical isolation of the pharynx from the remainder of the gut, which results in a nonfeeding period that can last up to 8 months. To determine how the gut microbiome is affected by metamorphosis, the microbial communities of feeding and nonfeeding larval and parasitic sea lamprey were surveyed using both culture-dependent and -independent methods. Our results show that the gut of the filter-feeding larva contains a greater diversity of bacteria than that of the blood-feeding parasite, with the parasite gut being dominated by Aeromonas and, to a lesser extent, Citrobacter and Shewanella. Phylogenetic analysis of the culturable Aeromonas from both the larval and parasitic gut revealed that at least five distinct species were represented. Phenotypic characterization of these isolates revealed that over half were capable of sheep red blood cell hemolysis, but all were capable of trout red blood cell hemolysis. This suggests that the enrichment of Aeromonas that accompanies metamorphosis is likely related to the sanguivorous lifestyle of the parasitic sea lamprey. PMID:22923392

Tetlock, Amanda; Yost, Christopher K; Stavrinides, John; Manzon, Richard G

2012-11-01

432

Involvement of Wnt signaling pathways in the metamorphosis of the bryozoan Bugula neritina.  

PubMed

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

433

Metamorphosis and acquisition of symbiotic algae in planula larvae and primary polyps of Acropora spp.  

NASA Astrophysics Data System (ADS)

Coral planulae settle, then metamorphose and form polyps. This study examined the morphological process of metamorphosis from planulae into primary polyps in the scleractinian corals Acropora nobilis and Acropora microphthalma, using the cnidarian neuropeptide Hym-248 . These two species release eggs that do not contain Symbiodinium. The mode of acquisition of freshly isolated Symbiodinium (zooxanthellae) (FIZ) by the non-symbiotic polyp was also examined. Non-Hym-248 treated swimming Acropora planulae did not develop blastopore, mesenteries or coelenteron until the induction of metamorphosis 16 days after fertilization. The oral pore was formed by invagination of the epidermal layer after formation of the coelenteron in metamorphosing polyps. At 3 days after settlement and metamorphosis, primary polyps exposed to FIZ established symbioses with the Symbiodinium. Two-four days after exposure to FIZ, the distribution of Symbiodinium was limited to the gastrodermis of the pharynx and basal part of the polyps. Eight-ten days after exposure to FIZ, Symbiodinium were present in gastrodermal cells throughout the polyps.

Hirose, M.; Yamamoto, H.; Nonaka, M.

2008-06-01

434

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

435

Evidence for an instructive role of apoptosis during the metamorphosis of Hydractinia echinata (Hydrozoa).  

PubMed

Apoptosis is a highly conserved mechanism of cell deletion that destroys redundant, dysfunctional, damaged, and diseased cells. Furthermore, apoptotic cell death is essential during the development of multicellular organisms. However, there are only a few examples where the occurrence of apoptosis has been shown to be a direct prerequisite for developmental processes. As described previously by our group, the degradation of larval tissue during the first half of the metamorphosis of Hydractinia echinata involves extensive cell death. A large number of cells are removed, and we observed several cellular features of apoptotic cell death in the dying tissue, e.g., nucleosomal DNA fragmentation and nuclear condensation. Furthermore, we showed that metamorphosis in the basal cnidarian H. echinata depends on the activity of caspases, the central enzymes of apoptosis. In the present study, we build on these previous investigations of apoptosis in H. echinata by characterising a caspase-3 sequence in this species and placing it in an evolutionary context by performing phylogenetic analyses. Furthermore, we report the successful knockdown of a caspase by RNAi and show that apoptosis plays a role as an instructive mechanism in the metamorphosis of H. echinata. PMID:21247747

Wittig, Karola; Kasper, Jennifer; Seipp, Stefanie; Leitz, Thomas

2011-02-01

436

Eel visual pigments revisited: the fate of retinal cones during metamorphosis.  

PubMed

During their complex life history, anguilliform eels go through a major metamorphosis when developing from a fresh water yellow eel into a deep-sea silver eel. In addition to major changes in body morphology, the visual system also adapts from a fresh water teleost duplex retina with rods and cones, to a specialized deep-sea retina containing only rods. The history of the rods is well documented with an initial switch from a porphyropsin to a rhodopsin (P523(2) to P501(1)) and then a total change in gene expression with the down regulation of a "freshwater" opsin and its concomitant replacement by the expression of a typical "deep-sea" opsin (P501(1) to P482(1)). Yellow eels possess only two spectral classes of single cones, one sensitive in the green presumably expressing an RH2 opsin gene and the second sensitive in the blue expressing an SWS2 opsin gene. In immature glass eels, entering into rivers from the sea, the cones contain mixtures of rhodopsins and porphyropsins, whereas the fully freshwater yellow eels have cone pigments that are almost pure porphyropsins with peak sensitivities at about 540-545 nm and 435-440 nm, respectively. However, during the early stages of metamorphosis, the pigments switch to rhodopsins with the maximum sensitivity of the "green"-sensitive cone shifting to about 525 nm, somewhat paralleling, but preceding the change in rods. During metamorphosis, the cones are almost completely lost. PMID:18321400

Bowmaker, James K; Semo, Ma'ayan; Hunt, David M; Jeffery, Glen

2008-01-01

437

Initial characterization of receptors for molecules that induce the settlement and metamorphosis of Haliotis rufescens larvae  

SciTech Connect

Larvae of the marine gastropod mollusc Haliotis refescens are induced to undergo metamorphosis by ..gamma..-aminobutyric acid (GABA) and stereochemically related compounds. The most potent of these inducers is (-)-..beta..-(parachlorophenyl)-GABA (baclofen). The inductive response exhibits positive cooperatively, and is subject to both facilitation (up-regulation) and habituation (down-regulation). Facilitation is brought about by diamino acids such as L-diaminopropionic acid (L-DAPA), and is characterized by decreased Hill coefficients (n/sub H/) and concentration requirements (EC/sub 50/) for inducers. Facilitation does not require the simultaneous presence of facilitating and inducing compounds, and the facilitated state is persistent. Larvae are capable of being up-regulated 2 days before they are capable of undergoing settlement and metamorphosis. Habituation can be brought about by exposure of pre-competent larvae to GABA 4 days prior to the attainment of competence; it is then slowly reversible. Larvae specifically bind tritiated (-)-baclofen in a manner that is saturable with both increasing time of exposure of larvae to, and with increasing concentration of, this compound. Specific binding can be competed for by unlabeled GABA-mimetic inducing molecules; the order of effectiveness of these molecules as competitors for specific binding correlates well with their effectiveness as inducers of metamorphosis. Facilitation of larvae by exposure to diamino acids does not alter their specific binding of tritiated (-)-baclofen. It is concluded from these findings that Haliotis larvae possess receptors for GABA-mimetic compounds.

Trapido-Rosenthal, H.G.

1985-01-01

438

Variation in pesticide tolerance of tadpoles among and within species of ranidae and patterns of amphibian decline  

USGS Publications Warehouse

There is significant variation among and within amphibian species with respect to reports of population decline; declining species are often found in environments that are physiograpically similar to environments where the same species is thriving. Because variability exists among organisms in their sensitivity to environmental stressors, it is important to determine the degree of this variation when undertaking conservation efforts. We conducted both lethal (time-to-death) and sublethal (activity change) assays to determine the degree of variation in the sensitivity of tadpoles to a pesticide, carbaryl, at three hierarchical levels: among ranid species, among several populations of a single ranid species (Rana sphenocephala), and within populations of R. sphenocephala. We observed significant variation in time to death among the nine ranid species and among the 10 R. sphenocephala populations we tested. Four out of eight R. sphenocephala populations exhibited significantly different times to death among families. The magnitude of the activity change in response to exposure to sublethal carbaryl levels was significantly different among species and within R. sphenocephala populations. Chemical contamination, at lethal or sublethal levels, can alter natural regulatory processes such as juvenile recruitment in amphibian populations and should be considered a contributing cause of declines in amphibian populations.

Bridges, C.M.; Semlitsch, R.D.

2000-01-01

439

Multiple stressor effects in relation to declining amphibian populations  

USGS Publications Warehouse

This book represents the work of several authors who participated in the symposium entitled 'Multiple Stressor Effects in Relation to Declining Amphibian Populations' convened 16-17 April, 2002, in Pittsburgh, Pennsylvania. Declines of amphibian populations of varying severity have been observed for many years, and in the last 8 to 10 years considerable progress has been made in documenting the status and distribution of a range of amphibian species. Habitat alteration and destruction are likely linked to many amphibian declines, but a variety of other factors, both anthropogenic and natural, have been observed or proposed to have caused declines or extinctions of amphibian populations. Unfortunately, determining the environmental causes for the decline of many species has proven difficult. The goals of this symposium were three-fold. First, highlight ASTM's historic role in providing a forum for the standardization of amphibian toxicity test methods and the characterization of adverse effects potentially associated with chemical stressors. Second, demonstrate through case studies the current state of technical 'tools' available to biologists, ecologists, environmental scientists and natural resource professionals for assessing amphibian populations exposed to various environmental stressors. And third, characterize a process that brings a range of interdisciplinary technical and management tools to the tasks of causal analysis, especially as those relate to a multiple stressor risk assessment 'mind-set.' As part of the symposium, scientists and resource management professionals from diverse fields including ecotoxicology and chemistry, ecology and field biology, conservation biology, and natural resource management and policy contributed oral presentations and posters that addressed topics related to declining amphibian populations and the role that various stressors have in those losses. The papers contained in this publication reflect the commitment of ASTM International committee E47 on Biological Fate and Environmental Effects to provide timely and comprehensive information to the technical community and the lay-public who have become increasingly aware of amphibians and their current plight. Common themes emphasized throughout the symposium can be found in this issue, including papers focused on (1) toxicity assessment, (2) integrated field and laboratory studies, and (3) causal analysis. In addition to historical accounts of the development of amphibian test methods and contemporary studies illustrating current applications of these methods, this publication addresses future needs by providing contributions focused on research requirements in these areas.

2003-01-01

440

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.

441

Development, organization, and remodeling of phoronid muscles from embryo to metamorphosis (Lophotrochozoa: Phoronida)  

PubMed Central

Background The phoronid larva, which is called the actinotrocha, is one of the most remarkable planktotrophic larval types among marine invertebrates. Actinotrochs live in plankton for relatively long periods and undergo catastrophic metamorphosis, in which some parts of the larval body are consumed by the juvenile. The development and organization of the muscular system has never been described in detail for actinotrochs and for other stages in the phoronid life cycle. Results In Phoronopsis harmeri, muscular elements of the preoral lobe and the collar originate in the mid-gastrula stage from mesodermal cells, which have immigrated from the anterior wall of the archenteron. Muscles of the trunk originate from posterior mesoderm together with the trunk coelom. The organization of the muscular system in phoronid larvae of different species is very complex and consists of 14 groups of muscles. The telotroch constrictor, which holds the telotroch in the larval body during metamorphosis, is described for the first time. This unusual muscle is formed by apical myofilaments of the epidermal cells. Most larval muscles are formed by cells with cross-striated organization of myofibrils. During metamorphosis, most elements of the larval muscular system degenerate, but some of them remain and are integrated into the juvenile musculature. Conclusion Early steps of phoronid myogenesis reflect the peculiarities of the actinotroch larva: the muscle of the preoral lobe is the first muscle to appear, and it is important for food capture. The larval muscular system is organized in differently in different phoronid larvae, but always exhibits a complexity that probably results from the long pelagic life, planktotrophy, and catastrophic metamorphosis. Degeneration of the larval muscular system during phoronid metamorphosis occurs in two ways, i.e., by complete or by incomplete destruction of larval muscular elements. The organization and remodeling of the muscular system in phoronids exhibits the combination of protostome-like and deuterostome-like features. This combination, which has also been found in the organization of some other systems in phoronids, can be regarded as an important characteristic and one that probably reflects the basal position of phoronids within the Lophotrochozoa. PMID:23617418

2013-01-01

442

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

443

Hexosaminidase assays  

Microsoft Academic Search

?-Hexosaminidases (EC 3.2.1.52) are lysosomal enzymes that remove terminal ?-glycosidically bound N-acetylglucosamine and N-acetylgalactosamine residues from a number of glycoconjugates. Reliable assay systems are particularly important for the\\u000a diagnosis of a family of lysosomal storage disorders, the GM2 gangliosidoses that result from inherited ?-hexosaminidase deficiency.\\u000a More recently, aberrant hexosaminidase levels have also been found to be associated with a variety

Michaela Wendeler; Konrad Sandhoff

2009-01-01

444

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

445

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

446

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

447

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

448

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

449

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

450

Advective and diffusive dermal processes for estimating terrestrial amphibian pesticide exposure  

EPA Science Inventory

Background/Question/Methods Dermal exposure presents a potentially significant but understudied route for pesticide uptake in terrestrial amphibians. Historically, evaluation of pesticide risk to both amphibians and reptiles has been achieved by comparing ingestion and inhalat...

451

A Resistant-Kernel Model of Connectivity for Amphibians that Breed in Vernal Pools  

E-print Network

was parameterized with empirical migration distances for spotted salamanders (Ambystoma maculatum), disper- sal at broader scales than traditional pool-based approaches. Keywords: Ambystomatidae, Ambystoma opacum, Ambystoma maculatum, amphibian conservation, metapopulation, pond-breeding amphibian, resistant-kernel model

452

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

453

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

454

Potential causes for amphibian declines in Puerto Rico  

USGS Publications Warehouse

We monitored 11 populations of eight species of Eleutherodactylus in Puerto Rico from 1989 through 2001. We determined relative abundance of active frogs along transects established in the Caribbean National Forest (El Yunque), Carite Forest, San Lorenzo, and in the vicinity of San Juan. Three species (Eleutherodactylus karlschmidti, E. jasperi, and E. eneidae) are presumed to be extinct and eight populations of six different species of endemic Eleutherodactylus are significantly declining at elevations above 400 m. Of the many suspected causes of amphibian declines around the world, we focused on climate change and disease. Temperature and precipitation data from 1970a??2000 were analyzed to determine the general pattern of oscillations and deviations that could be correlated with amphibian declines. We examined a total of 106 tissues taken from museum specimens collected from 1961a??1978 and from live frogs in 2000. We found chytrid fungi in two species collected at El Yunque as early as 1976, this is the first report of chytrid fungus in the Caribbean. Analysis of weather data indicates a significant warming trend and an association between years with extended periods of drought and the decline of amphibians in Puerto Rico. The 1970's and 1990's, which represent the periods of amphibian extirpations and declines, were significantly drier than average. We suggest a possible synergistic interaction between drought and the pathological effect of the chytrid fungus on amphibian populations.

Burrowes, P.A.; Joglar, R.L.; Green, David E.

2004-01-01

455

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

456

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

457

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

458

The Consequences of Metamorphosis on Salamander (Ambystoma) Locomotor Performance Author(s): H. Bradley Shaffer, C. C. Austin, R. B. Huey  

E-print Network

The Consequences of Metamorphosis on Salamander (Ambystoma) Locomotor Performance Author(s): H://links.jstor.org #12;212 TheConsequencesofMetamorphosison Salamander(Ambystoma)LocomotorPerformance H.BradleyShaffer1 C. Wequantify the effects of metamorphosis on burst speed and endurance capacity on a large sample ofAmbystoma

Shaffer, H. Bradley

459

Broad-complex functions in postembryonic development of the cockroach Blattella germanica shed new light on the evolution of insect metamorphosis  

E-print Network

light on the evolution of insect metamorphosis Jia-Hsin Huang 1 , Jesus Lozano, Xavier Belles Institute form 27 September 2012 Accepted 28 September 2012 Available online 3 October 2012 Keywords: Insect metamorphosis Juvenile hormone Ecdysone Evolution of holometaboly Drosophila Tribolium Background: Insect

Belles, Xavier

460

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.

461

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

462

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

463

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

464

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.

465

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.

466

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.

467

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

468

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.

469

Recent global amphibian declines are now un-equivocally linked to chytridiomycosis, an emergent  

E-print Network

Articles Recent global amphibian declines are now un- equivocally linked to chytridiomycosis the world; however, the reasons for its sudden emergence as an amphibian pathogen remain the subject disease has also been documented in temperate amphibian populations, where die-offs are more temporally

Rosenblum, Erica Bree

470

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

471

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

472

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

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

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.

475

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.

476

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