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1.
Zootaxa ; 5023(1): 121-130, 2021 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-34810973

RESUMO

In this work, we show that Bufo levicristatus Boettger, 1885 is a senior synonym of Bufo scitulus Caramaschi Niemeyer, 2003, and not a junior synonym of Bufo ornatus Spix, 1824, as previously considered. In addition, we present evidence that Bufo scitulus Caramaschi Niemeyer, 2003 complies with the International Code of Zoological Nomenclature requirements for a reversal of precedence over the name Bufo levicristatus Boettger, 1885, and so the name Bufo scitulus is to be maintained for this species.


Assuntos
Bufo bufo , Bufonidae , Animais , Paraguai
2.
J Pharm Biomed Anal ; 206: 114354, 2021 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-34509663

RESUMO

Animal venoms contain many peptides with high specificity and selectivity against their protein targets, a characteristic which makes venoms an invaluable source of potential drugs. High-sensitivity mass spectrometry (MS)- based peptidomic platform has evolved as a predominant method for natural peptide drug discovery due to its strength for direct and rapid identification of peptides and peptide-associated post-translational modifications (PTMs). In this study, we used cell-affinity assays combined with nanoLC-MS/MS based peptidomics to identify cancer cell binding peptides (CBPs) from Bufo Bufo gargarizans. We identified 76 potential cell binding peptides and 237 non-affinity peptides in venom extracts from Asiatic toads, and some were verified with MS-parallel reaction monitoring (PRM) mode. These peptides were further analyzed and internalized within human cells and some demonstrated anti-tumor properties in vitro. These specific peptides might be used as templates for peptide-based drug design or optimization.


Assuntos
Neoplasias , Espectrometria de Massas em Tandem , Animais , Bufo bufo , Detecção Precoce de Câncer , Humanos , Peptídeos
3.
Bull Environ Contam Toxicol ; 107(5): 848-854, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34414477

RESUMO

Nanotoxicity data for amphibians are limited compared to other taxonomic groups. The present study assessed toxicity of titanium dioxide nanoparticles (nanoTiO2, anatase form, particle size < 25 nm) on tadpoles of Duttaphrynus melanostictus after short term and chronic exposures. Exposure to nanoTiO2 (≤ 100 mg/L) for 96 h had no significant effect on survival but upon transfer to nanoTiO2 free water for another 21 days, survival of the tadpoles pre-exposed to nanoTiO2 was greatly reduced and their development was delayed. Chronic exposure to nanoTiO2 (0.1 to 10 mg/L) for 14 days had no significant effects on acetylcholinesterase activities but induced mortalities (up to 40%) and histological alterations in the intestine and liver tissues. The results indicate that release of nanoTiO2 to aquatic ecosystems could pose negative impacts to amphibian populations.


Assuntos
Bufo bufo , Nanopartículas , Acetilcolinesterase , Animais , Ecossistema , Larva , Nanopartículas/toxicidade , Titânio/toxicidade
4.
BMC Ecol Evol ; 21(1): 135, 2021 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-34217227

RESUMO

BACKGROUND: Batrachochytrium dendrobatidis (Bd) is the causative agent of chytridiomycosis, one of the major causes of worldwide amphibian biodiversity loss. Many amphibians exhibit skin-based chemical defences, which may play an important role against invading pathogens, but whether the synthesis of these chemical compounds is enhanced or suppressed in the presence of pathogens is largely unknown. Here we investigated direct and indirect effects of larval exposure to the globally distributed and highly virulent Bd-GPL strain on skin secreted chemical defences and life history traits during early ontogeny of agile frogs (Rana dalmatina) and common toads (Bufo bufo). RESULTS: Exposure to Bd during the larval stage did not result in enhanced synthesis of the antimicrobial peptide Brevinin-1 Da in R. dalmatina tadpoles or in increased production of bufadienolides in B. bufo tadpoles. However, exposure to Bd during the larval stage had a carry-over effect reaching beyond metamorphosis: both R. dalmatina and B. bufo froglets contained smaller quantities of defensive chemicals than their Bd-naïve conspecifics in the control treatment. Prevalence of Bd and infection intensities were very low in both larvae and metamorphs of R. dalmatina, while in B. bufo we observed high Bd prevalence and infection intensities, especially in metamorphs. At the same time, we did not find a significant effect of Bd-exposure on body mass or development rate in larvae or metamorphs in either species. CONCLUSIONS: The lack of detrimental effect of Bd-exposure on life history traits, even parallel with high infection intensities in the case of B. bufo individuals, is surprising and suggests high tolerance of local populations of these two species against Bd. However, the lowered quantity of defensive chemicals may compromise antimicrobial and antipredatory defences of froglets, which may ultimately contribute to population declines also in the absence of conspicuous mass-mortality events.


Assuntos
Bufo bufo , Quitridiomicetos , Animais , Anuros , Batrachochytrium , Humanos , Ranidae
5.
Dis Aquat Organ ; 145: 15-20, 2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34080579

RESUMO

Bufonid herpesvirus 1 (BfHV1) was initially described in 2014 from cases of mortalities and dermatitis in Swiss populations of the common toad Bufo bufo. We identified a closely related herpesvirus strain in a German common toad population affected by an ongoing epidemic of multifocal proliferative to ulcerative skin disease since 2018.


Assuntos
Bufo bufo , Herpesviridae , Animais , Alemanha/epidemiologia , Pele
6.
Heredity (Edinb) ; 126(4): 656-667, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33564181

RESUMO

Clinal variation is paramount for understanding the factors shaping genetic diversity in space and time. During the last glacial maximum, northern Europe was covered by glacial ice that rendered the region uninhabitable for most taxa. Different evolutionary processes during and after the recolonisation of this area from different glacial refugia have affected the genetic landscape of the present day European flora and fauna. In this study, we focus on the common toad (Bufo bufo) in Sweden and present evidence suggesting that these processes have resulted in two separate lineages of common toad, which colonised Sweden from two directions. Using ddRAD sequencing data for demographic modelling, structure analyses, and analysis of molecular variance (AMOVA), we provide evidence of a contact zone located between Uppland and Västerbotten in central Sweden. Genetic diversity was significantly higher in southern Sweden compared to the north, in accordance with a pattern of decreased genetic diversity with increasing distance from glacial refugia. Candidate genes under putative selection are identified through outlier detection and gene-environment association methods. We provide evidence of divergent selection related to stress response and developmental processes in these candidate genes. The colonisation of Sweden by two separate lineages may have implications for how future conservation efforts should be directed by identifying management units and putative local adaptations.


Assuntos
Bufo bufo , Deriva Genética , Genética Populacional , Seleção Genética , Animais , Evolução Biológica , Bufo bufo/genética , Variação Genética , Filogenia , Refúgio de Vida Selvagem
7.
Int J Biol Macromol ; 175: 67-78, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33548318

RESUMO

Bufadienolides are the main active ingredients of Venenum Bufonis, which is a widely used traditional Chinese medicine secreted from parotoid gland and skin glands of Bufo bufo gargarizans. According to the transcriptome analysis, "cholesterol-bile acid-bufadienolidies pathway" was proposed as animal-derived bufadienolides biosynthesis pathway by us previously. In this pathway 3ß-hydroxysteroid dehydrogenase (3ßHSD) and steroid 5ß-reductase (SRD5ß) might be the key enzymes to convert the A/B ring to cis-configuration. Therefore, as the second report of our group, here we report the cloning of the full length of SRD5ß cDNA of B. bufo gargarizans (Bbg-SRD5ß) from the parotoid gland of B. bufo gargarizans for the first time, and site-directed mutagenesis was used to explored the character of Bbg-SRD5ß. Bbg-SRD5ß had an open reading frame of 981 bp and encoded 326 amino acids residues. The expression conditions of the recombinant Bbg-SRD5ß in E. coli BL21 (DE3) harbored with pCold-Bbg-SRD5ß was optimized as induction for 10 h at 15 °C with 0.1 mM IPTG. With NADPH as a cofactor, Bbg-SRD5ß can reduce the Δ4,5 double bonds of progesterone to generate dihydroprogesterone õwithout substrate inhibition effect. The catalytic rate of mutant type Bbg-SRD5ß-Y132G was 1.8 times higher than that of wild type Bbg-SRD5ß. Although Bbg-SRD5ß was almost unable to reduce the progesterone to dihydroprogesterone after mutation of V309, the affinity of enzyme with NADPH changed significantly. Bbg-SRD5ß is the key enzymes to convert the A/B ring of steroid to cis-configuration, and V309 is a key site affecting the binding affinity of enzyme with NADPH, and the mutation of Y132 can adjust the catalytic rate of Bbg-SRD5ß.


Assuntos
Venenos de Anfíbios/química , Bufo bufo/metabolismo , Oxirredutases/isolamento & purificação , Sequência de Aminoácidos , Venenos de Anfíbios/metabolismo , Animais , Bufanolídeos/química , Bufanolídeos/metabolismo , Bufonidae/metabolismo , Clonagem Molecular/métodos , DNA Complementar/metabolismo , Fases de Leitura Aberta , Oxirredutases/genética , Oxirredutases/metabolismo , Esteroides/metabolismo
8.
Sci Total Environ ; 776: 145945, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33639467

RESUMO

Nowadays the presence of pharmaceuticals in the environment is a real problem. Ending up in aquatic environments they negatively affect non-target organisms. Considering the limited studies on the negative effects of pharmaceuticals in amphibians, a better understanding of the mechanisms underlying the sub-lethal effects of drug mixtures in wildlife is an urgent call. Representing particularly vulnerable organisms currently at risk of extinction, amphibians are perfect non-target organisms to explore the consequences of pharmaceuticals during sensitive life-stages. To address this existing research gap, the effects of two drugs, the antidepressant fluoxetine and the anti-inflammatory ibuprofen, as well as their combination has been studied. Tadpoles of Bufo bufo were exposed for seven days to two environmentally realistic concentrations of fluoxetine, ibuprofen and their mixture. The development, behavior and erythron profile were then evaluated as endpoints of exposure response. Both drugs negatively affected tadpoles' growth and development by significantly delayed their time to metamorphosis and reduced body weight. Behaviors were also impaired with a significant increase of unresponsiveness to different stimuli. Mutagenic analysis of blood revealed a significant increase in the frequency of cellular and nuclear abnormalities. Given the complexity of systems and functions affected, our work confirms the toxicological potential of fluoxetine and ibuprofen in B. bufo tadpoles by emphasizing their role as tadpole development delayers and erythrocyte apoptosis-inducers. To our knowledge, this is the first study trying to elucidate the potentially toxic effects of a mixture of an antidepressant with a non-steroidal anti-inflammatory drug using bullfrog tadpole as model organism. Both drugs interacted in impairing development and fitness in tadpoles, which might affect long-term species perpetuation and population dynamic. More in-depth research is needed to elucidate the nature of interaction and molecular mechanisms of mixed pharmaceutical compounds on non-targeted organisms.


Assuntos
Bufo bufo , Poluentes Químicos da Água , Animais , Apoptose , Fluoxetina/toxicidade , Ibuprofeno/toxicidade , Larva , Poluentes Químicos da Água/toxicidade
9.
Sci Rep ; 11(1): 260, 2021 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-33420098

RESUMO

Genetic diversity feeds the evolutionary process and allows populations to adapt to environmental changes. However, we still lack a thorough understanding of why hotspots of genetic diversity are so 'hot'. Here, we analysed the relative contribution of bioclimatic stability and genetic admixture between divergent lineages in shaping spatial patterns of genetic diversity in the common toad Bufo bufo along the Italian peninsula. We combined population genetic, phylogeographic and species distribution modelling (SDM) approaches to map ancestral areas, glacial refugia, and secondary contact zones. We consistently identified three phylogeographic lineages, distributed in northern, central and southern Italy. These lineages expanded from their ancestral areas and established secondary contact zones, before the last interglacial. SDM identified widespread glacial refugia in peninsular Italy, sometimes located under the present-day sea-level. Generalized linear models indicated genetic admixture as the only significant predictor of the levels of population genetic diversity. Our results show that glacial refugia contributed to preserving both levels and patterns of genetic diversity across glacial-interglacial cycles, but not to their formation, and highlight a general principle emerging in Mediterranean species: higher levels of genetic diversity mark populations with substantial contributions from multiple genetic lineages, irrespective of the location of glacial refugia.


Assuntos
Bufo bufo/genética , DNA Mitocondrial/genética , Variação Genética , Animais , Teorema de Bayes , Evolução Biológica , Genética Populacional , Haplótipos , Camada de Gelo , Itália , Repetições de Microssatélites/genética , Modelos Genéticos , Filogeografia , Refúgio de Vida Selvagem
10.
Ecotoxicology ; 30(2): 213-223, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33471271

RESUMO

Amphibian populations are declining worldwide at alarming rates. Among the large variety of contributing stressors, chemical pollutants like pesticides have been identified as a major factor for this decline. Besides direct effects on aquatic and terrestrial amphibian stages, sublethal effects like impairments in reproduction can affect a population. Therefore, we investigated the reproductive capacity of common toads (Bufo bufo) in the pesticide-intensive viticultural landscape of Palatinate in Southwest Germany along a pesticide gradient. In a semi-field study, we captured reproductively active common toad pairs of five breeding ponds with different pesticide contamination level and kept them in a net cage until spawning. Toads from more contaminated ponds showed an increased fecundity (more eggs) but decreased fertilization rates (fewer hatching tadpoles) as well as lower survival rates and reduced size in Gosner stage 25, suggesting that the higher exposed populations suffer from long-term reproductive impairments. In combination with acute toxicity effects, the detected sublethal effects, which are mostly not addressed in the ecological risk assessment of pesticides, pose a serious threat on amphibian populations in agricultural landscapes.


Assuntos
Bufo bufo , Praguicidas , Agricultura , Animais , Alemanha , Larva , Praguicidas/toxicidade , Reprodução
11.
PLoS One ; 15(11): e0242720, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33253276

RESUMO

Most agricultural soils are expected to be contaminated with agricultural chemicals. As the exposure to pesticides can have adverse effects on non-target organisms, avoiding contaminated areas would be advantageous on an individual level, but could lead to a chemical landscape fragmentation with disadvantages on the metapopulation level. We investigated the avoidance behavior of juvenile common toads (Bufo bufo) in response to seven pesticide formulations commonly used in German vineyards. We used test arenas filled with silica sand and oversprayed half of each with different pesticide formulations. We placed a toad in the middle of an arena, filmed its behavior over 24 hours, calculated the proportion of time a toad spent on the contaminated side and compared it to a random side choice. We found evidence for the avoidance of the folpet formulation Folpan® 500 SC, the metrafenone formulation Vivando® and the glyphosate formulation Taifun® forte at maximum recommended field rates for vine and a trend for avoidance of Wettable Sulphur Stulln (sulphur). No avoidance was observed when testing Folpan® 80 WDG (folpet), Funguran® progress (copper hydroxide), SpinTorTM (spinosad), or 10% of the maximum field rate of any formulation tested. In the choice-tests in which we observed an avoidance, toads also showed higher activity on the contaminated side of the arena. As video analysis with tracking software is not always feasible, we further tested the effect of reducing the sampling interval for manual data analyses. We showed that one data point every 15 or 60 minutes results in a risk of overlooking a weak avoidance behavior, but still allows to verify the absence/presence of an avoidance for six out of seven formulations. Our findings are important for an upcoming pesticide risk assessment for amphibians and could be a template for future standardized tests.


Assuntos
Aprendizagem da Esquiva/efeitos dos fármacos , Praguicidas/farmacologia , Poluentes Químicos da Água/farmacologia , Animais , Bufo bufo
12.
Molecules ; 25(19)2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33019706

RESUMO

Two new indole alkaloids, Bufotenidine B (2) and Bufocarboline A (6), along with seven known indole alkaloids (1, 3-5, and 7-9) and three organic acids (10-12), were isolated from the water extract of toad venom. The structures of the new alkaloids were elucidated by extensive spectroscopic methods. The absolute configurations of 4, 6, and 8 were determined for the first time by electronic circular dichroism (ECD) calculations. The cytotoxic activity of all compounds was tested against human malignant melanoma cells A375 by the MTT method, and no antitumor activity was observed.


Assuntos
Venenos de Anfíbios/química , Bufo bufo/metabolismo , Alcaloides Indólicos/isolamento & purificação , Animais , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Dicroísmo Circular , Alcaloides Indólicos/química , Espectroscopia de Prótons por Ressonância Magnética , Água/química
13.
Zoology (Jena) ; 142: 125822, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32862084

RESUMO

Anurans secrete a wide diversity of toxins from skin glands to defend themselves against predators and pathogens. Bufonids produce potent poison in parotoid macroglands located in the postorbital region. Parotoid secretion is a rich source of bioactive compounds with cardiotoxic, cytotoxic and hemolytic activity. Poison content and toxicity may vary between species, populations, and among conspecifics inhabiting the same area. In the present paper, we pre-analyzed the individual variation in cardiotoxicity of parotoid extract of common toads (Bufo bufo Linnaeus, 1758) and impact of body mass (BM), snout to vent length (SVL), and body condition (BC) of toad on the poison toxicity. We hypothesized that large toads produce poison with higher cardiotoxicity than smaller ones. Parotoid extract was fractionated by reverse phase chromatography, and then in vitro physiological bioassays were carried out on the semi-isolated hearts of the mealworm beetle (Tenebrio molitor Linnaeus, 1758) to determine cardiotoxicity of the whole poison and separated fractions. Generalized linear mixed models were used to determine effects of BM, SVL, and BC on the poison toxicity. We recorded significant changes in the insect heart contractility after treatment with the whole poison and separated fractions. We found an individual variation in cardiotoxicity of the parotoid extract which was explained by the body size of toad. Poison of smaller toads displayed a negative, whereas poison of larger toads positive, chronotropic effect on the heart contractility. Thus, we conclude that the effectiveness of parotoid secretion in repelling predators may vary depending on the toad individual size.


Assuntos
Bufo bufo/anatomia & histologia , Coração/efeitos dos fármacos , Glândula Parótida/fisiologia , Toxinas Biológicas/toxicidade , Animais , Secreções Corporais , Tamanho Corporal , Bufo bufo/fisiologia , Feminino , Masculino , Tenebrio/efeitos dos fármacos
14.
J Chem Ecol ; 46(5-6): 534-543, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32468489

RESUMO

Many organisms synthesize secondary metabolites against natural enemies. However, to which environmental factors the production of these metabolites is adjusted to is poorly investigated in animals, especially so in vertebrates. Bufadienolides are steroidal compounds that are present in a wide range of plants and animals and, if present in large quantities, can provide protection against natural enemies, such as pathogens. In a correlative study involving 16 natural populations we investigated how variation in bufadienolide content of larval common toads (Bufo bufo) is associated with the bacterial community structure of their aquatic environment. We also evaluated pond size, macrovegetation cover, and the abundance of predators, conspecifics and other larval amphibians. We measured toxin content of tadpoles using HPLC-MS and determined the number of bufadienolide compounds (NBC) and the total quantity of bufadienolides (TBQ). AICc-based model selection revealed strong relationships of NBC and TBQ with bacterial community structure of the aquatic habitat as well as with the presence of conspecific tadpoles. The observed relationships may have arisen due to adaptation to local bacterial communities, phenotypic plasticity, differential biotransformation of toxin compounds by different bacterial communities, or a combination of these processes. Bacterial groups that contribute to among-population variation in toxin content remain to be pinpointed, but our study suggesting that toxin production may be influenced by the bacterial community of the environment represents an important step towards understanding the ecological and evolutionary processes leading to microbiota-mediated variation in skin toxin profiles of aquatic vertebrates.


Assuntos
Bactérias , Bufanolídeos/química , Bufo bufo , Larva/química , Microbiota , Lagoas/microbiologia , Animais , Bufo bufo/crescimento & desenvolvimento , Hungria
15.
Environ Pollut ; 259: 113883, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31931411

RESUMO

Artificial Light At Night (ALAN) is an emerging pollution, that dramatically keeps on increasing worldwide due to urbanisation and transport infrastructure development. In 2016, it nearly affected 23% of the Earth's surface. To date, all terrestrial and aquatic ecosystems have been affected. The disruption of natural light cycles due to ALAN is particularly expected for nocturnal species, which require dark periods to forage, move, and reproduce. Apart from chiropterans, amphibians contain the largest proportion of nocturnal species among vertebrates exhibiting an unfavourable conservation status in most parts of the world and living in ALAN polluted areas. Despite the growing number of studies on this subject, our knowledge on the direct influence of nocturnal lighting on amphibians is still scarce. To better understand the consequences of ALAN on the breeding component of amphibian fitness, we experimentally exposed male breeding common toads (Bufo bufo) to ecologically relevant light intensities of 0.01 (control), 0.1 or 5 lux for 12 days. At mating, exposed males took longer than controls to form an amplexus, i.e. to pair with a female, and broke amplexus before egg laying, while controls never did. These behavioural changes were associated with fitness alteration. The fertilisation rate of 5 lux-exposed males was reduced by 25%. Salivary testosterone, which is usually correlated with reproductive behaviours, was not altered by ALAN. Our study demonstrates that ALAN can affect the breeding behaviour of anuran species and reduce one component of their fitness. Given the growing importance of ALAN, more work is needed to understand its long-term consequences on the behaviour and physiology of individuals. It appears essential to identify deleterious effects for animal populations and propose appropriate management solutions in an increasingly brighter world.


Assuntos
Bufo bufo , Luz , Comportamento Sexual Animal , Animais , Bufo bufo/fisiologia , Ecossistema , Feminino , Masculino , Fotoperíodo , Comportamento Sexual Animal/fisiologia , Comportamento Sexual Animal/efeitos da radiação
16.
Sci Total Environ ; 706: 134430, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31855631

RESUMO

Two important drivers of the global amphibian decline are habitat destruction due to an intensification of farming and a related increase of pesticide applications. Recent studies have shown that there might be an underestimated risk of pesticides on terrestrial amphibians. However, there are too few data on the terrestrial habitat use of amphibians in agricultural landscapes to estimate the exposure risk. To fill this knowledge gap, we used telemetry to investigate the post-breeding migration of 51 common toads (Bufo bufo) from a breeding pond in a vineyard-dominated landscape in Southern Palatinate (Germany). We expected most toads to migrate to the nearby Palatinate Forest as a terrestrial habitat. However, only four individuals reached the forest, suggesting that a part of the population is inhabiting the agricultural landscape over large parts of the year. Individuals were also found directly in the vineyards (15% of all relocations), but 23% less often than expected from a random choice and therefore tend to avoid vineyards as terrestrial habitat. To estimate a possible spatial-temporal overlap of toad migration and pesticide application, we combined telemetry data with information about pesticide applications from local wine growers. Seven individuals had a high probability (>75%) of being directly exposed to a pesticide application. Taking spray drift and the half-life values of applied pesticides into account, the number of toads potentially exposed raised to 15 individuals. We estimated that, on a single day up to 24% of the whole breeding population came in contact with pesticides, resulting in a high overall exposure risk. Pesticides can have negative effects on amphibians, and toads try to avoid vineyards as habitats. Therefore, we conclude that a heterogeneous cultural landscape, with buffer strips around ponds, uncultivated patches and migration corridors, might be the best management measure for sustaining amphibians in the agricultural landscape.


Assuntos
Bufo bufo , Animais , Cruzamento , Ecossistema , Fazendas , Alemanha , Praguicidas
17.
Environ Sci Pollut Res Int ; 27(3): 3034-3042, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31838683

RESUMO

Agricultural activity, especially the increasing use of pesticides, is considered one of the main reasons for the decline of amphibian populations. Mancozeb (MCZ) is one of the most used fungicides worldwide, despite its ancient use and toxicity demonstrated in different taxa. However, there is limited information about the effects of MCZ in amphibians, which are keystones of riparian ecosystems. For species conservation purposes, it is essential to identify the most sensitive developmental period(s) of a given species to a xenobiotic. We evaluated the toxicity of a commercial fungicide of mancozeb, (80% active ingredient) on the early development of the common South American toad Rhinella arenarum (Anura, Bufonidae). Embryos from early blastula (S.4) and larvae from complete operculum (S.25) stages were exposed to a wide range of MCZ concentrations during acute, subchronic and chronic exposure (up to 504 h) periods. The toxicity profiles for lethal and sublethal effects were performed. At all exposure times, MCZ was more toxic to embryos, for instance, NOEC 504 h were 0.01 and 0.05 mg MCZ/L for embryos and larvae, respectively. Thus, embryo sensitivity was 5-fold higher than larvae. A Teratogenic Index of 14 indicated the significant teratogenic potential of this fungicide. Among sublethal effects, embryos exhibited a wide range of abnormalities with high incidence. The ecological risk assessment demonstrated that the estimated Risk Quotient value for Rhinella arenarum embryos at chronic exposure was higher than the Level of Concern value, which warns about the potential risk of MCZ for this native species.


Assuntos
Bufo bufo , Fungicidas Industriais/toxicidade , Maneb/toxicidade , Zineb/toxicidade , Animais , Bufo arenarum , Bufonidae , Ecossistema , Embrião não Mamífero , Larva , Medição de Risco
18.
Sci Rep ; 9(1): 17236, 2019 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-31754241

RESUMO

Chemical defences are widespread in nature, yet we know little about whether and how climatic and geographic factors affect their evolution. In this study, we investigated the natural variation in the concentration and composition of the main bufogenin toxin in adult Asian toads (Bufo gargarizans Cantor) captured in twenty-two regions. Moreover, we explored the relative importance of eight climatic factors (average temperature, maximum temperature, minimum temperature, average relative humidity, 20-20 time precipitation, maximum continuous precipitation, maximum ground temperature, and minimum ground temperature) in regulating toxin production. We found that compared to toads captured from central and southwestern China, toads from eastern China secreted higher concentrations of cinobufagin (CBG) and resibufogenin (RBG) but lower concentrations of telocinobufagin (TBG) and cinobufotalin (CFL). All 8 climatic variables had significant effects on bufogenin production (ri>0.5), while the plastic response of bufogenin toxin to various climate factors was highly variable. The most important climatic driver of total bufogenin production was precipitation: the bufogenin concentration increased with increasing precipitation. This study indicated that the evolution of phenotypic plasticity in chemical defences may depend at least partly on the geographic variation of defensive toxins and their climatic context.


Assuntos
Bufo bufo/metabolismo , Bufo bufo/fisiologia , Animais , Bufanolídeos/metabolismo , Geografia/métodos , Temperatura , Toxinas Biológicas/metabolismo
19.
Mol Ecol ; 28(23): 5145-5154, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31643124

RESUMO

Classical theory states that hybrid zones will be stable in troughs of low population density where dispersal is hampered. Yet, evidence for moving hybrid zones is mounting. One possible reason that moving zones have been underappreciated is that they may drive themselves into oblivion and with just the superseding species remaining, morphological and genetic signals of past species replacement may be difficult to appreciate. Using genetic data (32 diagnostic single nucleotide polymorphisms) from a clinal hybrid zone of the common toad (Bufo bufo) and the spined toad (Bufo spinosus) in France for comparison, alleles of the latter species were documented in common toads in the south of Great Britain, at frequencies in excess of 10%. Because long distance dispersal across the Channel is unlikely, the conclusion reached was that the continental toad hybrid zone which previously extended into Britain, moved southwards and extirpated B. spinosus. Species distribution models for the mid-Holocene and the present support that climate has locally changed in favour of B. bufo. The system bears resemblance with the demise of Homo neanderthalensis and the rise of Homo sapiens and provides an example that some paleoanthropologists demanded in support of a hominin "leaky replacement" scenario. The toad example is informative just because surviving pure B. spinosus and an extant slowly moving interspecific hybrid zone are available for comparison.


Assuntos
Bufo bufo/genética , Genética Populacional , Hibridização Genética , Alelos , Animais , Bufo bufo/fisiologia , Clima , França , Especiação Genética , Polimorfismo de Nucleotídeo Único/genética , Densidade Demográfica , Reino Unido
20.
Int. j. morphol ; 37(3): 1172-1178, Sept. 2019. tab, graf
Artigo em Inglês | LILACS | ID: biblio-1012413

RESUMO

The morphological and histological structure of the brains of Bufo gargarizans and Cynops orientalis were observed by anatomy and light microscopy. The results show that the brains of Bufo gargarizans and Cynops orientalis are divided into 5 parts which include the telencephalon, diencephalon, mesencephalon, cerebellum and medulla oblongata. The telencephalon consists of the olfactory bulb and the cerebral hemisphere. The olfactory bulb is developed that has two pairs of olfactory nerve. Bufo gargarizan has a symmetrical oval hemisphere optic lobes; Cynops orientalis only has a spherical optic lobe. The cerebellum is situated behind the optic lobe and closely connected with the myelencephalon. In this paper, the morphological and histological differences between the two species are discussed. The proportion of cerebral hemisphere is gradually increasing, which correlated with a progressive increase in the number of neuronal cell classes, and reflected in behavior complexity.


La estructura morfológica e histológica de los cerebros de Bufo gargarizans y Cynops orientalis se observó mediante anatomía y microscopía óptica. Los resultados muestran que los cerebros de Bufo gargarizans y Cynops orientalis se dividen en 5 partes, que incluyen el telencéfalo, diencéfalo, mesencéfalo, cerebelo y mielencéfalo. El telencéfalo consiste en bulbo olfatorio y hemisferio cerebral. El bulbo olfatorio tiene dos pares de nervios olfatorios. Los lóbulos ópticos de Bufo gargarizans son ovalados y simétricos en ambos hemisferios cerebrales; Cynops orientalis tiene solo un lóbulo óptico esférico. El cerebelo está situado detrás del lóbulo óptico y está estrechamente conectado con el mielencéfalo. En este trabajo, se discuten las diferencias morfológicas e histológicas entre las dos especies. El tamaño del hemisferio cerebral aumenta gradualmente, lo que se correlaciona con un aumento progresivo de células neuronales en los núcleos, reflejándose en la complejidad del comportamiento.


Assuntos
Animais , Salamandridae/anatomia & histologia , Encéfalo/anatomia & histologia , Bufo bufo/anatomia & histologia , Anatomia Comparada , Telencéfalo/anatomia & histologia , Mesencéfalo/anatomia & histologia , Cerebelo/anatomia & histologia , Diencéfalo/anatomia & histologia , Mielencéfalo/anatomia & histologia
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