We documented new records of Choloepus didactylus extending up to 820 km south of its current geographic distribution. These records, and others found in literature for the central‐southern Amazon, ...evidence a southern expansion of about 30% of the known species' area of occurrence and help shedding light on decades of uncertainties about its real distribution.
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Resumo
Neste estudo, documentamos novos registros da “Preguiça de Dois Dedos”, Choloepus didactylus (Linnaeus, 1758) estendendo‐se até 820 km ao sul de sua distribuição geográfica atual. Esses registros, e outros encontrados na literatura para o centro‐sul da Amazônia, evidenciam uma expansão para o sul de cerca de 30% da área de ocorrência da espécie conhecida e ajudam a esclarecer décadas de incertezas sobre sua real distribuição.
We documented new records of Choloepus didactylus extending up to 820 km south of its current geographic distribution. These records, and others found in literature for the central‐southern Amazon, evidence a southern expansion of about 30% of the known species' area of occurrence and help shedding light on decades of uncertainties about its real distribution.
Parental care increases offspring survival, but may impose costs by decreasing adult survival or mating opportunities. Because individuals have limited resources, time allocation and risk decisions ...are expected to vary according to the care status and threat faced by parents. Herein, we evaluated the sources of mortality of clutches of the glassfrog Hyalinobatrachium cappellei and the importance of paternal care for offspring survival. We also compared time allocation patterns and antipredator behavior between attending and non-attending males. Using naturalistic observations and field experiments with different dummy predators, we hypothesized that (1) offspring survival would be positively correlated with paternal care; (2) attending males would spend most of the time caring for the embryos, while non-attending males would spend more time foraging and calling; (3) attending males would prioritize their own survival when facing a high risk of predation, even with negative impacts on offspring survival. Main sources of embryo mortality included predation and dehydration, and offspring survivorship was almost totally dependent on paternal care. Although non-attending males spent more time calling and foraging, attending males also called and were able to attract females and increase their mating success. However, contrary to our prediction, we found that attending males were more risk-tolerant, increasing not only offspring survival but also their mortality risk. Our findings highlight the importance of the predation risk level on parents’decisions and that the reproductive status may play a significant role in determining antipredator behavior and mating success in glassfrog males.
The secreted poisonin bufonids (Anura: Bufonidae) include proteins, biogenic amines, toxic bufadienolides and alkaloids. The chemical composition of the methanolic extract of parotoid gland ...secretions by the Amazonian toad Rhinella margaritifera was evaluated in a UFLC-DAD-micrOTOF system. Of the twenty three compounds found in the methanolic extract, eighteen were identified by the mass/charge ratio as: five arginine diacids, six bufagenins (telocinobufagin, marinobufagin, bufotalin, cinobufotalin, bufalin and cinobufagin), six bufotoxins, and an alkaloid (dehydrobufotenin).
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•Rhinella margaritifera has a wide distribution throughout the Amazon basin.•The R. margaritifera poison presented arginines, bufagenins, bufotoxins and alkaloid.•Bufotalin was the major compound found in the R. margaritifera poison.
While most anurans have limited vagility and local fidelity, there are some exceptions. In the present study, we used
Boana boans
, a large treefrog found throughout most of the Amazon basin, as a ...model organism. We investigated the possible isolation of the
B. boans
demes located on opposite margins of the Juruena River and their population structure. We sampled 14 individuals of
B. boans
and analyzed the mitochondrial D-Loop to verify whether the river or Euclidean distance is acting as barrier to the dispersal of this frog. The sequencing revealed 12 haplotypes, with global
Fst
values of − 0.079, K2P values ranging from − 0.187 to 0.054, and primarily intrapopulation (81.78%) genetic diversity, with only 18.22% of the variation being found among populations. Analysis of molecular variance and Bayesian cluster analysis detected a lack of genetic structuring within the study area. The model species presented a capacity for dispersal over long distances in comparison with most other amphibians, which, together with its resistance to desiccation and reproductive mode, enable this treefrog to disperse across rivers and overland. In the specific case of Juruena River, many fluvial islands present within the study area may also be favorable to the dispersal of the species.
Rhinella marina toad is abundant in Brazil. Its poison contains cardiac glycosides called bufadienolides, which are extensively investigated for their bioactivity. Our aim was to characterize the ...vasoactivity of Rhinella marina poison (RmP) on the aorta of male Wistar rats. For this, the RmP was first collected and processed to obtain an alcoholic extract. To determine cardiovascular effects of RmP, we performed in vivo tests by administering RmP intravenously in doses of 0.1-0.8 mg/kg. Vascular reactivity was also performed through concentration-response curves to RmP (10 ng/mL to 200 μg/mL) in aortic segments with and without endothelium. RmP induced a concentration-dependent contraction in rat aorta which was partly endothelium-mediated. Nitric oxide contributes with this response in view that incubation with L-NAME increased the contractile response. Additionally, treatment with indomethacin cyclooxygenase, (COX) inhibitor, nifedipine (L-type voltage-gated calcium channels blocker), and BQ-123 (ET
receptors antagonist) decreased maximum response, and ketanserin (5-HT
receptors antagonist) decreased pEC
, suggesting active participation of these pathways in the contractile response. On the other hand, apocynin (NADPH oxidase inhibitor) did not alter contractility. Incubation with prazosin (α
-adrenergic receptor antagonist) abolished the contractile response, suggesting that the RmP-induced contraction is dependent on the adrenergic pathway. In the Na
/K
ATPase protocol, a higher Emax was observed in the RmP experimental group, suggesting that RmP potentiated Na
/K
ATPase hyperpolarizing response. When this extract was injected (i.v.) in vivo, increase in blood pressure and decrease in heart rate were observed. The results were immediate and transitory, and occurred in a dose-dependent manner. Overall, these data suggest that the poison extract of R. marina toad has an important vasoconstrictor action and subsequent vasopressor effects, and its use can be investigated to some cardiovascular disorders.
Cutaneous secretions produced by amphibians of the family Bufonidae are rich sources of bioactive compounds that can be useful as new chemical templates for agrochemicals. In crop protection, the use ...of elicitors to induce responses offers the prospect of durable, broad-spectrum disease control using the plant's own resistance. Therefore, we evaluated the potential of methanolic extracts of cutaneous secretions of two species of amphibians of the family Bufonidae found in the Amazon biome-Rhaebo guttatus (species 1) and Rhinella marina (species 2)-in the synthesis of phytoalexins in soybean cotyledons, bean hypocotyls, and sorghum mesocotyls. Additionally, changes in the enzyme activity of β-1,3-glucanase, peroxidase (POX), and polyphenol oxidase (PPO) and in the total protein content of soybean cotyledons were determined. In the soybean cultivar 'TMG 132 RR', our results indicated that the methanolic extract of R. guttatus cutaneous secretions suppressed glyceollin synthesis and β-1,3-glucanase activity and increased POX and PPO activities at higher concentrations and total protein content at a concentration of 0.2 mg/mL. On the other hand, the methanolic extract of R. marina cutaneous secretions induced glyceollin synthesis in the soybean cultivars 'TMG 132 RR' and 'Monsoy 8372 IPRO' at 0.1-0.2 mg/mL and 0.2 mg/mL, respectively. The methanolic extract of R. marina cutaneous secretions also increased the specific activity of POX and PPO in 'Monsoy 8372 IPRO' and 'TMG 132 RR', respectively, and decreased the activity of β-1,3-glucanases in 'Monsoy 8372 IPRO'. At 0.3 mg/mL, it stimulated phaseolin synthesis. The extracts did not express bioactivity in the synthesis of deoxyanthocyanidins in sorghum mesocotyls. The study in soybean suggests that the bioactivity in defense responses is influenced by cultivar genotypes. Therefore, these results provide evidence that extracts of cutaneous secretions of these amphibians species may contribute to the bioactivity of defense metabolites in plants.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Amphibian cutaneous secretion has great potential for bioprospection and is a great tool in the development of bioproducts. Thus, the objective of the present work was to evaluate the comparative ...study of the chemical profile parotoid gland secretions from Rhaebo guttatus collected in two distinct regions of the Brazilian Amazon. For this, the chemical composition of six methanolic extracts of this species were analyzed by Liquid Chromatography in UV and MS Detection Ultra-Chromatography Systems (UFLC-DAD-micrOTOF). All obtained chromatograms presented two distinct regions; one referring to the more hydrophilic molecules (alkaloids), while the other refers to the more hydrophobic compounds (steroids). The steroid region resembles all samples, regardless of where they were collected. In the alkaloid region, there was a standardized variation for the samples from the southern Brazilian Amazon, but the same was not true for the samples collected in the Amazon-Cerrado transition region. Thus, the data suggest that the environment and diet of R. guttatus may be important in alkaloid production, but do not influence steroid content. These results add new information about the poison of the toad R. guttatus and raises new questions to be further investigated, thus contributing to the knowledge of the anuran fauna of the Brazilian Amazon.
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•The poison of the amphibian R. guttatus contains indole alkaloids and cardiotonic steroids.•R. guttatus poison from the Cerrado showed more alkaloids than the southern Amazon.•The chemical composition of R. guttatus poison is influenced by the environment.
In this study, we evaluate the effects of spatial and environmental factors on the structure of tadpole assemblages in Central Amazonia testing the following hypotheses: (1) environmental factors are ...more important than spatial ones in tadpole richness distribution and (2) habitat structure variables are more important than biotic variables in tadpole richness distribution. Tadpoles were sampled at 20 riparian plots between February and June 2010. Spatial and environmental components explained the major part of the variation in observed and estimated tadpole richness, respectively. Among all fitted models, the best model that explains species richness distribution is the one that contains only the number of ponds. Our results showed that tadpole richness in streamside ponds is influenced by niche-based processes and can be explained by local factors related to habitat structure. Predator density was not an important biotic factor in our study, contradicting the results found by other studies conducted in tropical areas. However, neutral processes are also important because spatial variation can explain the spatial distribution of species richness, probably as a result of dispersal limitation. Therefore, our results contribute to understanding of the local and landscape features which influence the amphibian species diversity in a tropical forest.
•A bufadienolide extracted from cane toad (compound 1) inhibits Na,K-ATPase.•Compound 1 decreases Na,K-ATPase expression.•Compound 1 activates caspase 3 and 9 to induce cell apoptosis.
Bufadienolide ...compounds have been used for growth inhibition and apoptosis induction in tumor cells. Those families of cardiotonic steroids can bind the Na,K-ATPase, causing its inhibition. The use of bufadienolides is widely described in the literature as an anticancer function. The aim of this study was to evaluate the effects of bufadienolides and alkaloid isolated from venom samples from R. marina on tumor cells. We performed cytotoxicity assay in MDA-MB-231 and TOV-21G cells and evaluated the activity of Caspases (3 and 9), Na, K-ATPase, PMCA and SERCA. Four compounds were extrated from the venom of R. marina. The compound 1 showed higher cytotoxicity in MDA-MB-231cells. Compound 1 also showed activation of Caspase 3 and 9. This compound caused an inhibition of the activity and expression of Na, K-ATPase, and also showed activation of both caspase-9 and caspase-3 in MDA-MB-231 cells. We also observed that Compound 1 had a direct effect on some ATPases, such as Na, K-ATPase, PMCA and SERCA. Compound 1 was able to inhibit the activity of the purified Na, K-ATPase enzyme from the concentration of 5 µM. It also caused inhibition of PMCA at all concentrations tested (1 nM-30 µM). However, the compound 1 led to an increase of the activity of purified SERCA between the concentrations of 7.5–30 µM. Thus, we present a Na, K-ATPase and PMCA inhibitor, which may lead to the activation of caspases 3 and 9, causing the cells to enter into apoptosis. Our study suggests that compound 1 may be an interesting molecule as an anticancer agent.
Chemical compounds from skin secretions from toads of Bufonidae family have been long-studied. In the search for new molecules with pharmacological action, the 3β-OH groups of bufadienolides are ...commonly derivatised using acetyl groups. This work described the isolation and/or structural elucidation of isolated and derivatised compounds from the venom of the Brazilian anuran Rhinella marina, and their evaluation in in vitro assays. In the methanolic extract of the R. marina venom, compound cholesterol (1) was isolated from the CRV-52 fraction by classic column chromatography, dehydrobufotenine (2) by Sephadex LH-20 from the CRV-28 fraction, and a mix of suberoyl arginine (3) and compound 2 was obtained from the CRV-6-33 fraction. The compounds marinobufagin (4), telocionbufagin (5) and bufalin (6) were isolated by classic column chromatography, followed by separation via HPLC in the CRV-70 fraction, and the compound marinobufotoxin (9) was isolated by classic column chromatography in the CRV-6 fraction, here being isolated for the first time in R. marina specimens. Compounds 4 and 5 were submitted for acetylation with acetic anhydride, in the presence of pyridine and 4-dimethyilaminopiridine (DMAP), in order to obtain the compounds 3-acetyl-marinobufagin (7) and 3-acetyl-telocinobufogin (8). The isolated and derivatised compounds were identified by 1H and 13C NMR, and their molecular mass confirmed by mass spectrometry. All compounds (except 1 and 3) were tested in cytotoxic assays by the MTT method and presented cytotoxic potential against human cancer cell lines, as well as against non-tumoral human embryonic kidney HEK-293 cells. With the exception of compound 2, all molecules presented IC50 values < 4 μM, and none caused hemolysis of human erythrocytes, demonstrating a promising cytotoxic potential of natural and chemically-modified bufadienolides. This study presents a detailed contribution of bioactive chemicals from Brazilian Amazon Rhinella species, and indicates promising areas for further studies and pharmaceutical investments.
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•Seven compounds were identified in the extract from Rhinella marina venom.•Compounds 4 and 5 were acetylated resulting in the compounds 7 and 8.•Marinobufotoxin (9) was isolated for the first time in Rhinella marina.•The tested compounds demonstrated potent activity against tumour cell lines.
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