Frog Research Articles

Operation Frog Effect by Sarah Scheerger

Operation Frog Effect by Sarah Scheerger

Verrucous lymphangioma circumscriptum in a child

Lymphangioma circumscriptum (LC) is characterized by dilation of lymphatic vessels in the skin and subcutaneous tissue. It presents as asymptomatic vesicles filled with lymphatic fluid giving characteristic frog spawn appearance, but does not progress into warty plaque. LC can also be divided into congenital and acquired form. The common sites are axillary folds, shoulder, upper arm, scrotum, penis, rectum, and vulva. It needs to be differentiated from certain common conditions such as herpes zoster, molluscum contagiosum, hemangioma, verruca vulgaris, and angiokeratoma. Surgical modality is the first choice of treatment. A case of a 5-year-old girl having verrucous plaque on the right knee joint diagnosed as LC is presented here.

Age structures and growth parameters of the Levantine frog, Pelophylax bedriagae, at different localities in Denizli, Turkey

Skeletochronology is a reliable tool for assessing several parameters in amphibian populations. We used skeletochronology to determine the age structure, growth rate, age at first reproduction, and longevity of Levantine frog Pelophylax bedriagae populations from different localities in Denizli, Turkey. All examined individuals (N = 161) exhibited Lines of Arrested Growth in the bone cross-sections. Age structure and age at first reproduction were similar among localities and sexes, while longevity and growth rates showed significant variation among localities. Obtained results were compared with literature data on age-related and grow parameters in Pelophylax bedriagae and cognate species.

The relationship between brain size and digestive tract length do not support expensive-tissue hypothesis in Hylarana guentheri

The brain is among the most energetically costly organs in the vertebrate body. The expensive-tissue hypothesis (ETH) predicts that increasing the size of another costly organ, such as the gut, should compensate for the cost of a small brain. To date, this hypothesis has mainly been tested in homoeothermic animals and in some ectothermic animals (e.g., fishes and anurans). Here, we undertake a test of the ETH by analyzing the relationship between brain size variation and length of the digestive tract in Hylarana guentheri . After controlling for geographical situation and body size, we did not find a correlation between brain mass and the length of the digestive tract in H. guentheri . Our findings suggest that the variation of brain size did not follow general patterns in this species and that the effect of diet quality cannot play a role in the variation of brain.

Cross-body communication is electric in the froglet

Cross-body communication is electric in the froglet

Frog Water

Frog Water

The Frog & the Fish: Reflections on Work, Technology, Sex, Stuff, Truth, and Happiness

The Frog & the Fish: Reflections on Work, Technology, Sex, Stuff, Truth, and Happiness

New insights on the phylogenetic position and population genetic structure of the Critically Endangered Karpathos marsh frog Pelophylax cerigensis (Amphibia: Anura: Ranidae)

The genus Pelophylax , which currently comprises 26 species, is a well studied group due to its complex history and high diversification, although some phylogenies remain unresolved. Here we assess the phylogenetic position and the population genetic structure of the Critically Endangered Karpathos frog, Pelophylax cerigensis , endemic to Karpathos Island. A total of 42 cytb sequences were examined including specimens from Rhodes Island, and amplified fragment length polymorphisms (AFLPs) were generated to investigate the genetic structure and connectivity of the only two known populations on Karpathos. Molecular analyses reveal two major waterfrog lineages in the eastern Mediterranean: Clade A comprises Pelophylax bedriagae from the Middle East and the island of Cyprus, while clade B includes both P. bedriagae from the east Aegean Sea and P. cerigensis . Specimens from Karpathos and Rhodes constitute a single clade, contrasting previous studies, thus indicating the occurrence of Karpathos frog also to the neighboring Rhodes. The AFLP markers revealed low but statistically significant levels of genetic divergence between the two Karpathos’ populations and similar levels of genetic diversity. Our results suggest that the current taxonomy of the species should be re-evaluated. We also strongly recommend the need of conservation actions to maintain the levels of diversity in the declining population of the Karpathos frog.

Electric circuit theory applied to alien invasions: a connectivity model predicting the Balkan frog expansion in Northern Italy

Invasive species are a major threat to biodiversity and alien herpetofauna already caused conservation problems in Italy and in the world. Pelophylax kurtmuelleri (Gayda, 1940) is a water frog native to Southern Balkans, that was introduced in NW Italy (Liguria) in 1941, from where it has spread to Piedmont, Lombardy and recently to Emilia Romagna. Surprisingly, during its expansion, the Balkan frog seemed not to be able to cross the Po River (with a single exception). So, we investigated the reasons for such directional limitation of range expansion, focusing on the potential role of the Po River. Combining ecological niche and connectivity models, we adopted a two-step process in order to assess: (i) if the habitat suitability differs between the two sides of the Po Plain; (ii) if the Po River could act as a barrier in terms of dispersal. Results showed that the northern side of the plain seems less suitable than the southern one, even if many suitable patches occur along the main left tributaries of the Po River and in the hilly part of the plain. The Po River behaves like a barrier for the Balkan frog, but the only known point on the north bank of the river indicates that it may be able to only slow the dispersal and not to completely stop it. So, the most probable interpretation for the absence of the Balkan frog from the Northern Po Plain, is the combination of habitat suitability and connectivity issues: the former makes less probable that new viable populations can establish in the North, the latter decreases the northwards flux of the frogs. Given these findings, the Balkan frog seems able to spread in the whole Northern Italy and the colonization of the northern Po plain could happen shortly.

Identification and differential regulation of microRNAs during thyroid hormone-dependent metamorphosis in Microhyla fissipes

BackgroundAnuran metamorphosis, which is obligatorily initiated and sustained by thyroid hormone (TH), is a dramatic example of extensive morphological, biochemical and cellular changes occurring during post-embryonic development. Thus, it provides an ideal model to understand the actions of the hormone and molecular mechanisms underlying these developmental and apoptotic processes. In addition to transcriptional factors, microRNAs (miRNAs) play key roles in diverse biological processes via post-transcriptional repression of mRNAs. However, the possible role of miRNAs in anuran metamorphosis is not well understood. Screening and identification of TH-responding miRNAs are required to reveal the integrated regulatory mechanisms of TH during metamorphosis. Given the specific role of TRs during M. fissipes metamorphosis and the characteristics of M. fissipes as an ideal model, Illumina sequencing technology was employed to get a full scope of miRNA in M. fissipes metamorphosis treated by T3.ResultsMorphological and histological analysis revealed that 24 h T3 treatment M. fissipes tadpoles resembled that at the climax of natural metamorphosis. Thus, small RNA libraries were constructed from control and 24 h T3 treatment groups. A total of 164 conserved miRNAs and 36 predicted novel miRNAs were characterized. Furthermore, 5′ first and ninth nucleotides of miRNAs were significantly enriched in U in our study. In all, 21 miRNAs were differentially expressed between the T3 and control groups (p < 0.01). A total of 10,206 unigenes were identified as target genes of these differentially expressed miRNAs. KEGG pathway analysis indicated that the most overrepresented miRNA target genes were enriched in the “PI3k-Akt signaling pathway”. In addition, a network associated with the TH signaling pathway provides an opportunity to further understand the complex biological processes that occur in metamorphosis.ConclusionsWe identified a large number of miRNAs during M. fissipes metamorphosis, and 21 of them were differentially expressed in the two groups that represented two different metamorphic stages. These miRNAs may play important roles during metamorphosis. The study gives us clues for further studies of the mechanisms of anuran metamorphosis and provides a model to study the mechanism of TH-affected biological processes in humans.

Methods for Investigating the Larval Period and Metamorphosis in Xenopus.

Anuran metamorphosis resembles postembryonic development in mammals, a period around birth when many organs/tissues mature into their adult form as circulating thyroid and stress hormone levels are high. Unlike uterus-enclosed mammalian embryos, tadpoles develop externally and undergo the dramatic changes of hormone-dependent development totally independent of maternal influence, making them a valuable model in which to study vertebrate postembryonic organ development and maturation. Various protocols have been developed and/or adapted for studying metamorphosis in Xenopus laevis and X. tropicalis, two highly related and well-studied frog species. Here, we introduce some of the methods for contemporary cell and molecular studies of gene function and regulation during metamorphosis.

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

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

New Occurrences of Anomalous Specimens of Anuran Amphibians in Northwest Upper Poochye

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Feeding habits of the bromeligenous treefrog Phyllodytes edelmoi Peixoto, Caramaschi & Freire, 2003 (Anura: Hylidae) from the State of Alagoas, Northeastern Brazil

The hylid frog genus Phyllodytes comprised 12 species distributed in eastern Brazil and known to strictly inhabit inside bromeliads. In this study, we explore the feeding habits of P. edelmoi and test the prey selectivity of the species by comparing the prey items in the stomachs contents with the availability of preys in bromeliads. Our results show that P. edelmoi consumes high amounts of ants along the year, and therefore it could be considered an “ant specialist” species. This specialist feeding behaviour could be considered a synapomorphy of the genus Phyllodytes .

First Record of Liuixalus feii Yang, Rao et Wang, 2015 (Anura: Rhacophoridae) from Vietnam and Taxonomic Assignment of L. jinxiuensis Li, Mo, Xie et Jiang, 2015

Liuixalus feii Yang, Rao et Wang, 2015, a small tree frog species recently described from Heishiding Nature Reserve, Fengkai County, Guangdong Province, Southern China, is recorded for the first time from Vietnam based on two specimens from Bac Giang Province. The newly collected specimens from Vietnam slightly differ from the type series from China in dorsal color pattern as well as by a low genetic divergence of 0.1% (16S rRNA fragment). In addition, our molecular analyses revealed L. jinxiuensis Li, Mo, Xie et Jiang, 2015 from Jinxiu, China to represent a junior synonym of L. feii .

Amphibians of the Reserva Ecológica Michelin: a high diversity site in the lowland Atlantic Forest of southern Bahia, Brazil.

An inventory of the amphibians of the Reserva Ecológica Michelin – REM in southern Bahia, Brazil is presented. Sixty-nine species were recorded during a ten-year sampling period. Amphibians were distributed in two orders (Gymnophiona and Anura), belonging to twelve families [Aromobatidae (1), Bufonidae (3), Centrolenidae (1), Craugastoridae (5), Eleutherodactylidae (3), Hemiphractidae (2), Hylidae (34), Phyllomedusidae (5) Leptodactylidae (7), Microhylidae (4), Odontophrynidae (3) and Caeciliidae (1)]. Fifty per cent of the reproductive modes known for Atlantic forest anurans were recorded. While no threatened species were found at REM, six species are classified as data deficient (DD) by the Brazilian Red List of threatened species and deserve additional attention. Phasmahyla timbo and Vitreorana eurygnatha are listed as endangered in Bahia according to the list of threatened species of the state. Despite a higher diversity of amphibians in the Atlantic forest having been reported for mountainous regions, our results revealed that amphibian richness for lowland forests is also high.

Diet Composition of Japanese Tree Frog (Hyla japonica) in a Rice Paddy, South Korea

Diet Composition of Japanese Tree Frog (Hyla japonica) in a Rice Paddy, South Korea

Feature Selection for Opinion Mining Using Shuffled Frog Leaping Algorithm

An essential part of our information-collecting behavior has always been to find out what other people think. With the growing availability and popularity of opinion-rich resources such as online review sites and personal blogs, new opportunities and challenges arise as people now can, and do, actively use information technologies to seek out and understand the opinions of others. Hence, Sentiment Analysis research has increased tremendously in recent times. Sentiment analysis deals with the methods that automatically process the text contents and extract the opinion of the users. In this work, biomedical opinions are extracted from twitter which contains many features needed to classify the opinions. However, such datasets contain many irrelevant or weak correlation features which influence the predictive accuracy of classification. Without a feature selection algorithm, it is difficult for the existing classification techniques to accurately identify patterns in the features. The purpose of feature selection is to not only identify a feature subset from original set of features but also to reduce the computation overhead in data mining .In the proposed feature selection approach, Shuffled Frog Leaping Algorithm (SFLA) algorithm optimizes the process of feature selection and yields the best optimal feature subset which increases the predictive accuracy of the classifier. SFLA is used as a feature selector and generates the feature subset and Naive Bayes, SVM and K-nn classification used to evaluate the feature subset produced. Experimental results show that the Naive Bayes classification produces better accuracy when the selected features from shuffled frog leaping algorithm are used.

Metabolomic insights into the effects of thyroid hormone on Rana [Lithobates] catesbeiana metamorphosis using whole-body Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging (MALDI-MSI)

Anuran metamorphosis involves the transformation of an aquatic tadpole into a juvenile frog. This process is completely dependent upon thyroid hormones (THs). Although much research has been focused on changes in gene expression programs during this postembryonic developmental period, transitions in the metabolic profiles are relatively poorly understood. Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging (MALDI-MSI) is a technique that generates highly multiplexed mass spectra while retaining spatial location information on a thin tissue section. Reconstructed ion heat maps are correlated with morphology of the tissue section for biological interpretation. The present study is the first to use whole-body MALDI-MSI on tadpoles to gain insights into anuran metamorphosis. Approximately 1000 features were detected in each of five tissues examined (brain, eye, liver, notochord, and tail muscle) from premetamorphic North American bullfrog (Rana [Lithobates] catesbeiana) tadpoles. Of these detected metabolites, 1700 were unique and 136 were significantly affected by exposure to 50 nM thyroxine for 48 h. Of the significantly-affected metabolites, 64 features were tentatively identified using the MassTRIX annotation tool. All tissues revealed changes in lipophilic compounds including phosphatidylcholines, phosphatidylinositols, phosphatidylglycerols, phosphatidylethanolamines, and phosphatidylserines. These lipophilic compounds made up the largest portion of significantly-affected metabolites indicating that lipid signaling is a major target of TH action in frog tadpoles.

The Diversity Amphibian (Order Anura) on Diefferent Habitat Types in Balik Bukit Resort Bukit Barisan Selatan National Park

Balik Bukit Resort Bukit Barisan Selatan National Park (BBSNP) is a protected area where various amphibians habitat. The conditions and quality of habitat, of course determines the diversity of amphibians. This study aimed to analyze the diversity to detect that the amphibians (order Anura), comparing the diversity of amphibians (order Anura) based on different types of habitat and identifying amphibian habitat conditions (order Anura) in Resort Balik Bukit of Bukit Barisan Selatan National Park. This study uses three replications in each habitat type (primary forest, bush and swamp) and using Visual Encounter Surveys in amphibian biodiversity data retrieval. The data have been analyzed using the Shannon Wiener index, and community similarity index by calculating the evenness. Research shows that the value of diversity is still classified as being on the three types of habitat with the highest diversity found in primary forest habitat that habitat conditions in Resort Behind the hill is still ensure the growth and proliferation of amphibians order Anura.Keywords: Anura, Amphibians, Environmental Indicators, Resort Balik Bukit TNBBS