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Maurer ML, Goyco-Blas JF, Kohl KD. Dietary tannins alter growth, behavior, and the gut microbiome of larval amphibians. Integr Zool 2024; 19:585-595. [PMID: 37551631 DOI: 10.1111/1749-4877.12758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Abstract
Research has shown that leached plant toxins negatively impact the growth and development of larval amphibians. However, tadpoles may encounter these same toxins in food material, and differential exposure routes and distribution of toxic chemicals can yield variable downstream effects on animals. To date, most research understanding the interactions between dietary plant toxins and herbivores has been conducted in terrestrial systems. Despite the abundance of plant toxins in food and water sources, the effects of dietary plant toxins on larval amphibians have not been studied, and tannins could negatively affect these species. Here, green frog tadpoles (Lithobates clamitans) were fed diets with or without 2% tannic acid to test how their growth, development, behavior, and gut microbiome respond to dietary tannins. At the end of the trial, we conducted a behavioral assay to measure tadpole activity and boldness and inventoried the gut microbiome using 16S rRNA sequencing. Dietary tannins significantly decreased body mass by 66% and length by 28%, without influencing tadpole developmental stage. We found significant differences in exploratory behavior and boldness during the first minute of our behavioral assay, demonstrating that tannins have the potential to influence behavior during novel or stressful events. Finally, tannins significantly sculpted the gut microbiome, with an increase in the measurement of Shannon entropy. We observed 7 microbial phyla and 153 microbial genera that exhibited significantly differential abundances differences between control and tannic acid-fed tadpoles. Collectively, our results demonstrate that dietary tannins have the potential to alter amphibian growth, behavior, and microbiome.
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Affiliation(s)
- Maya L Maurer
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - José F Goyco-Blas
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Kevin D Kohl
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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2
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La Pietra A, Imperatore R, Coccia E, Mobilio T, Ferrandino I, Paolucci M. Comparative Study of Condensed and Hydrolysable Tannins during the Early Stages of Zebrafish Development. Int J Mol Sci 2024; 25:7063. [PMID: 39000172 PMCID: PMC11241311 DOI: 10.3390/ijms25137063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 06/17/2024] [Accepted: 06/24/2024] [Indexed: 07/16/2024] Open
Abstract
In this study, we present data on the effects of condensed tannins (CTs) and hydrolysable tannins (HTs), polyphenols extracted from plants, at different concentrations on zebrafish development to identify the range of concentrations with toxic effects. Zebrafish embryos were exposed to CTs and HTs at two different concentration ranges (5.0-20.0 μgL-1 and 5.0-20.0 mgL-1) for 72 h. The toxicity parameters were observed up to 72 h of treatment. The uptake of CTs and HTs by the zebrafish larvae was assessed via HPLC analysis. A qRT-PCR analysis was performed to evaluate the expressions of genes cd63, zhe1, and klf4, involved in the hatching process of zebrafish. CTs and HTs at 5.0, 10.0, and 20.0 μgL-1 were not toxic. On the contrary, at 5.0, 10.0, and 20.0 mgL-1, HTs induced a delay in hatching starting from 48 h of treatment, while CTs showed a delay in hatching mainly at 48 h. The analysis of gene expression showed a downregulation in the group exposed to HTs, confirming the hatching data. We believe that this study is important for defining the optimal doses of CTs and HTs to be employed in different application fields such as the chemical industry, the animal feed industry, and medical science.
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Affiliation(s)
| | - Roberta Imperatore
- Department of Sciences and Technologies, University of Sannio, 82100 Benevento, Italy
| | - Elena Coccia
- Department of Sciences and Technologies, University of Sannio, 82100 Benevento, Italy
| | - Teresa Mobilio
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy
| | - Ida Ferrandino
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy
| | - Marina Paolucci
- Department of Sciences and Technologies, University of Sannio, 82100 Benevento, Italy
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3
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Magee-Christian RE, Earl JE. Effects of Leaf Litter Species on Cope's Gray Treefrog Oviposition Site Selection. ICHTHYOLOGY & HERPETOLOGY 2022. [DOI: 10.1643/h2021096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
| | - Julia E. Earl
- School of Biological Sciences, Louisiana Tech University, Ruston, Louisiana 71272; (REM) ; and (JEE)
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4
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Burrow A, Maerz J. How plants affect amphibian populations. Biol Rev Camb Philos Soc 2022; 97:1749-1767. [PMID: 35441800 DOI: 10.1111/brv.12861] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 11/28/2022]
Abstract
Descriptions of amphibian habitat, both aquatic and terrestrial, often include plants as characteristics but seldom is it understood whether and how those plants affect amphibian ecology. Understanding how plants affect amphibian populations is needed to develop strategies to combat declines of some amphibian populations. Using a systematic approach, we reviewed and synthesized available literature on the effects of plants on pond-breeding amphibians during the aquatic and terrestrial stages of their life cycle. Our review highlights that plant communities can strongly influence the distribution, abundance, and performance of amphibians in multiple direct and indirect ways. We found three broad themes of plants' influence on amphibians: plants can affect amphibians through effects on abiotic conditions including the thermal, hydric, and chemical aspects of an amphibian's environment; plants can have large effects on aquatic life stages through effects on resource quality and abundance; and plants can modify the nature and strength of interspecific interactions between amphibians and other species - notably predators. We synthesized insights gained from the literature to discuss how plant community management fits within efforts to manage amphibian populations and to guide future research efforts. While some topical areas are well researched, we found a general lack of mechanistic and trait-based work which is needed to advance our understanding of the drivers through which plants influence amphibian ecology. Our literature review reveals the substantial role that plants can have on amphibian ecology and the need for integrating plant and amphibian ecology to improve research and management outcomes for amphibians.
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Affiliation(s)
- Angela Burrow
- Warnell School of Forestry and Natural Resources, University of Georgia, 180 E Green Street, Athens, GA, 30602-2152, U.S.A
| | - John Maerz
- Warnell School of Forestry and Natural Resources, University of Georgia, 180 E Green Street, Athens, GA, 30602-2152, U.S.A
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5
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Xie Z, Wang M, Deng Y, Li J, Li J, Pang W, Xie L, Jiang D, Huang Z, He T, Yang G. Acute toxicity of eucalyptus leachate tannins to zebrafish and the mitigation effect of Fe 3+ on tannin toxicity. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 229:113077. [PMID: 34915221 DOI: 10.1016/j.ecoenv.2021.113077] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/06/2021] [Accepted: 12/09/2021] [Indexed: 06/14/2023]
Abstract
Fish ponds polluted by the black water of eucalyptus forests (formed by the complexation of eucalyptus tannins with Fe3+) have experienced fish deaths. However, the toxicity of the components of black water is still unclear. To study the acute toxicities of eucalyptus leachate tannins to fish, their changes in the presence of Fe3+, and the underlying mechanisms, the static bioassay test method was adopted for acute exposure testing of zebrafish. Zebrafish were exposed to three kinds of tannins, namely, tannic acid (TA), epigallocatechin gallate (EGCG) and tannins from fresh eucalyptus leaf leacheate (TFL), and to solutions of these tannins with different molar ratios of Fe3+, under both no-aeration and aeration conditions. The results showed that the 48 h LC50 values of TA, EGCG and TFL were respectively 92, 47, and 186 mg·L-1, under no aeration, and 171, 86, and 452 mg·L-1 under aeration. When Fe3+ at 2, 1, and 6 times the molar amount of tannin was added to LC100 solutions of TA, EGCG and TFL, zebrafish mortality in 24 h was reduced to 0-33%. Acute fish death in eucalyptus plantation areas is related to high concentrations of eucalyptus tannins in the water. However, with increasing dissolved oxygen and Fe3+ levels, the acute toxicity of tannins to fish can be reduced. Thus, the black water in eucalyptus plantation areas reflects a water quality phenomenon that reduces the acute toxicity of eucalyptus tannins to fish. The mechanism of tannin toxicity to fish may be related to the impairment of oxygen delivery by fish blood, but the mechanism needs further study. These results provide a scientific basis for the prevention and control of fish suffering from acute eucalyptus tannin poisoning in eucalyptus plantation areas and for the protection of water resources.
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Affiliation(s)
- Zhifeng Xie
- Forestry College of Guangxi University, Guangxi Key Laboratory of Forest Ecology and Conservation, No. 100 Daxue Road, Nanning 530004, China
| | - Miaoling Wang
- Forestry College of Guangxi University, Guangxi Key Laboratory of Forest Ecology and Conservation, No. 100 Daxue Road, Nanning 530004, China
| | - Yusong Deng
- Forestry College of Guangxi University, Guangxi Key Laboratory of Forest Ecology and Conservation, No. 100 Daxue Road, Nanning 530004, China
| | - Jining Li
- Forestry College of Guangxi University, Guangxi Key Laboratory of Forest Ecology and Conservation, No. 100 Daxue Road, Nanning 530004, China
| | - Jiantao Li
- Forestry College of Guangxi University, Guangxi Key Laboratory of Forest Ecology and Conservation, No. 100 Daxue Road, Nanning 530004, China
| | - Wending Pang
- Forestry College of Guangxi University, Guangxi Key Laboratory of Forest Ecology and Conservation, No. 100 Daxue Road, Nanning 530004, China
| | - Liujun Xie
- Forestry College of Guangxi University, Guangxi Key Laboratory of Forest Ecology and Conservation, No. 100 Daxue Road, Nanning 530004, China
| | - Daihua Jiang
- Guangxi Key Laboratory of Agro-Environment and Agro-Product Safety, Guangxi University, Nanning 530004, China
| | - Zhigang Huang
- Guangxi Key Laboratory of Agro-Environment and Agro-Product Safety, Guangxi University, Nanning 530004, China
| | - Tieguang He
- Institute of Agricultural Resources and Environment, Guangxi Academy of Agricultural Sciences, Nanning 530007, China
| | - Gairen Yang
- Forestry College of Guangxi University, Guangxi Key Laboratory of Forest Ecology and Conservation, No. 100 Daxue Road, Nanning 530004, China.
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6
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Native anurans threatened by the alien tree Ligustrum lucidum in a seasonal subtropical forest. Biol Invasions 2021. [DOI: 10.1007/s10530-021-02617-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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7
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Burrow AK, Maerz JC. Experimental confirmation of effects of leaf litter type and light on tadpole performance for two priority amphibians. Ecosphere 2021. [DOI: 10.1002/ecs2.3729] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Angela K. Burrow
- Warnell School of Forestry and Natural Resources University of Georgia Athens Georgia 30602 USA
| | - John C. Maerz
- Warnell School of Forestry and Natural Resources University of Georgia Athens Georgia 30602 USA
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8
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Bundschuh M, Zubrod JP, Wernicke T, Konschak M, Werner L, Brühl CA, Baudy P, Schulz R. Bottom-up effects of fungicides on tadpoles of the European common frog ( Rana temporaria). Ecol Evol 2021; 11:4353-4365. [PMID: 33976815 PMCID: PMC8093721 DOI: 10.1002/ece3.7332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 01/25/2021] [Accepted: 02/03/2021] [Indexed: 11/24/2022] Open
Abstract
Biodiversity is under pressure worldwide, with amphibians being particularly threatened. Stressors related to human activity, such as chemicals, are contributing to this decline. It remains, however, unclear whether chemicals exhibiting a fungicidal activity could indirectly affect tadpoles that depend on microbially conditioned leaf litter as food source. The indirect effect of fungicides (sum concentration of a fungicide mixture composed of azoxystrobin, carbendazim, cyprodinil, quinoxyfen, and tebuconazole: 100 µg/L) on tadpoles was assessed relative to leaf litter colonized by microbes in absence of fungicides (control) and a worst-case scenario, that is leached leaf litter without microbial colonization. The quality of leaf litter as food for tadpoles of the European common frog (Rana temporaria) was characterized through neutral lipid fatty acid profiles and microbial sum parameters and verified by sublethal responses in tadpoles (i.e., feeding rate, feces production, growth, and fatty acid composition). Fungicides changed the nutritious quality of leaf litter likely through alterations in leaves' neutral lipid fatty acid profiles (i.e., changes in some physiologically important highly unsaturated fatty acids reached more than 200%) in combination with a potential adsorption onto leaves during conditioning. These changes were reflected by differences in the development of tadpoles ultimately resulting in an earlier start of metamorphosis. Our data provide a first indication that fungicides potentially affect tadpole development indirectly through bottom-up effects. This pathway is so far not addressed in fungicide environmental risk assessment and merits further attention.
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Affiliation(s)
- Mirco Bundschuh
- iES LandauInstitute for Environmental SciencesUniversity of Koblenz‐LandauLandauGermany
- Department of Aquatic Sciences and AssessmentSwedish University of Agricultural SciencesUppsalaSweden
| | - Jochen P. Zubrod
- iES LandauInstitute for Environmental SciencesUniversity of Koblenz‐LandauLandauGermany
- Eusserthal Ecosystem Research StationUniversity of Koblenz‐LandauLandauGermany
| | - Theo Wernicke
- iES LandauInstitute for Environmental SciencesUniversity of Koblenz‐LandauLandauGermany
- Present address:
UFZ Department of Ecological ChemistryHelmholtz Centre for Environmental ResearchLeipzigGermany
| | - Marco Konschak
- iES LandauInstitute for Environmental SciencesUniversity of Koblenz‐LandauLandauGermany
| | - Leon Werner
- iES LandauInstitute for Environmental SciencesUniversity of Koblenz‐LandauLandauGermany
| | - Carsten A. Brühl
- iES LandauInstitute for Environmental SciencesUniversity of Koblenz‐LandauLandauGermany
| | - Patrick Baudy
- iES LandauInstitute for Environmental SciencesUniversity of Koblenz‐LandauLandauGermany
| | - Ralf Schulz
- iES LandauInstitute for Environmental SciencesUniversity of Koblenz‐LandauLandauGermany
- Eusserthal Ecosystem Research StationUniversity of Koblenz‐LandauLandauGermany
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9
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Earl JE. Leaf litter input to ponds can dramatically alter amphibian morphological phenotypes. Oecologia 2021; 195:145-153. [PMID: 33386461 DOI: 10.1007/s00442-020-04819-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 12/04/2020] [Indexed: 10/22/2022]
Abstract
Phenotypic plasticity in growth and development is commonly examined, but morphology can exhibit plasticity as well. Leg length plasticity is important, because it impacts mobility, which affects predator avoidance, prey capture, and seasonal movements. Differences in relative (i.e., body size adjusted) hind leg lengths > 5% in anurans affect jumping abilities, and resource levels and predation can generate these differences. Leaf litter input can alter larval growth and development and likely morphology as well. I show that relative leg length [leg length/snout-to-vent length (SVL) × 100%] can be quite variable, ranging from 44% of SVL to 120% of SVL across the following species: Hyla versicolor, Lithobates sylvaticus, L. sphenocephalus, and Anaxyrus americanus. Within species variability was highest in L. sylvaticus and almost as great as across species. I measured relative leg length for metamorphs from aquatic mesocosm studies examining the effects of plant litter type and quality. I also examined the relative importance of different environmental variables, including water quality, predation, resource level, and temperature. Good predictors were found only for the two ranids, where leaf litter input was the only variable found to affect relative leg length. Ranid frogs had longer legs when emerging from mesocosms with grass than mesocosms with no litter input, and deciduous leaves produced metamorphs intermediate in leg length. These results suggest that habitat changes in vegetation from land use change, invasive species, and climate change may affect the mobility and fitness of individuals through changes in metamorph relative leg length.
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Affiliation(s)
- Julia E Earl
- School of Biological Sciences, Louisiana Tech University, Box 3179, Ruston, LA, 71272, USA.
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10
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Host food quality and quantity differentially affect Ascogregarina barretti parasite burden, development and within-host competition in the mosquito Aedes triseriatus. Parasitology 2019; 146:1665-1672. [PMID: 31362793 DOI: 10.1017/s0031182019000994] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Host condition depends in large part on the quality and quantity of available food and heavily influences the outcome of parasite infection. Although parasite fitness traits such as growth rate and size may depend on host condition, whether host food quality or quantity is more important to parasite fitness and within-host interactions is poorly understood. We provided individual mosquito hosts with a standard dose of a gregarine parasite and reared mosquitoes on two food types of different quality and two quantities. We measured host size, total parasite count and area, and average size of parasites within each treatment. Food quality significantly influenced the number of parasites in a host; hosts fed a low-quality diet were infected with more parasites than those provided a high-quality diet. In addition, we found evidence of within-host competition; there was a negative relationship between parasite size and count though this relationship was dependent on host food quality. Host food quantity significantly affected total parasite area and parasite size; lower food quantity resulted in smaller parasites and reduced overall parasite area inside the host. Thus both food quality and quantity have the potential to influence parasite fitness and population dynamics.
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11
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Westby KM, Sweetman BM, Van Horn TR, Biro EG, Medley KA. Invasive species reduces parasite prevalence and neutralizes negative environmental effects on parasitism in a native mosquito. J Anim Ecol 2019; 88:1215-1225. [DOI: 10.1111/1365-2656.13004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/03/2019] [Indexed: 11/29/2022]
Affiliation(s)
- Katie M. Westby
- Tyson Research Center Washington University in St. Louis Eureka Missouri
| | | | - Thomas R. Van Horn
- Tyson Research Center Washington University in St. Louis Eureka Missouri
| | - Elizabeth G. Biro
- Tyson Research Center Washington University in St. Louis Eureka Missouri
| | - Kim A. Medley
- Tyson Research Center Washington University in St. Louis Eureka Missouri
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12
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Dodd CE, Buchholz R. Apparent Maladaptive Oviposition Site Choice of Cope's Gray Treefrogs (Hyla chrysoscelis) When Offered an Array of Pond Conditions. COPEIA 2018. [DOI: 10.1643/ce-18-049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Goldspiel HB, Newhouse AE, Powell WA, Gibbs JP. Effects of transgenic American chestnut leaf litter on growth and survival of wood frog larvae. Restor Ecol 2018. [DOI: 10.1111/rec.12879] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Harrison B. Goldspiel
- Department of Environmental and Forest Biology State University of New York College of Environmental Science and Forestry 1 Forestry Drive, Syracuse NY 13210 U.S.A
| | - Andrew E. Newhouse
- Department of Environmental and Forest Biology State University of New York College of Environmental Science and Forestry 1 Forestry Drive, Syracuse NY 13210 U.S.A
| | - William A. Powell
- Department of Environmental and Forest Biology State University of New York College of Environmental Science and Forestry 1 Forestry Drive, Syracuse NY 13210 U.S.A
| | - James P. Gibbs
- Department of Environmental and Forest Biology State University of New York College of Environmental Science and Forestry 1 Forestry Drive, Syracuse NY 13210 U.S.A
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14
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Samat N, Ng MF, Ruslan NF, Okuda KS, Tan PJ, Patel V. Interference Potential of Tannins and Chlorophylls in Zebrafish Phenotypic-Based Assays. Assay Drug Dev Technol 2018; 16:408-419. [PMID: 29985634 DOI: 10.1089/adt.2017.833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Natural products are prolific producers of diverse chemical scaffolds, which have yielded several clinically useful drugs. However, the complex features of natural products present challenges for identifying bioactive molecules using high-throughput screens. For most assays, measured endpoints are either colorimetric or luminescence based. Thus, the presence of the major metabolites, tannins, and chlorophylls, in natural products could potentially interfere with these measurements to give either false-positive or false-negative hits. In this context, zebrafish phenotypic assays provide an alternative approach to bioprospect naturally occurring bioactive compounds. Whether tannins and/or chlorophylls interfere in zebrafish phenotypic assays, is unclear. In this study, we evaluated the interference potential of tannins and chlorophylls against efficacy of known small-molecule inhibitors that are known to cause phenotypic abnormalities in developing zebrafish embryos. First, we fractionated tannin-enriched fraction (TEF) and chlorophyll-enriched fraction (CEF) from Camellia sinensis and cotreated them with PD0325901 [mitogen-activated protein kinase-kinase (MEK) inhibitor] and sunitinib malate (SM; anti-[lymph]angiogenic drug). While TEF and CEF did not interfere with phenotypic or molecular endpoints of PD0325901, TEF at 100 μg/mL partially masked the antiangiogenic effect of SM. On the other hand, CEF (100 μg/mL) was toxic when treated up to 6 dpf. Furthermore, CEF at 100 μg/mL potentially enhanced the activity of γ-secretase inhibitors, resulting in toxicity of treated embryos. Our study provides evidence that the presence of tannin and/or chlorophyll in natural products do interfere with zebrafish phenotype assays used for identifying potential hits. However, this may be target/assay dependent and thus requiring additional optimization steps to assess interference potential of tannins and chlorophylls before performing any screening assay.
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Affiliation(s)
| | - Mei Fong Ng
- Cancer Research Malaysia , Subang Jaya, Selangor, Malaysia
| | | | | | - Pei Jean Tan
- Cancer Research Malaysia , Subang Jaya, Selangor, Malaysia
| | - Vyomesh Patel
- Cancer Research Malaysia , Subang Jaya, Selangor, Malaysia
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15
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Stephens JP, Altman KA, Berven KA, Tiegs SD, Raffel TR. Bottom-up and trait-mediated effects of resource quality on amphibian parasitism. J Anim Ecol 2016; 86:305-315. [PMID: 28027571 DOI: 10.1111/1365-2656.12613] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 11/10/2016] [Indexed: 11/30/2022]
Abstract
Leaf litter subsidies are important resources for aquatic consumers like tadpoles and snails, causing bottom-up effects on wetland ecosystems. Recent studies have shown that variation in litter nutritional quality can be as important as litter quantity in driving these bottom-up effects. Resource subsidies likely also have indirect and trait-mediated effects on predation and parasitism, but these potential effects remain largely unexplored. We generated predictions for differential effects of litter nutrition and secondary polyphenolic compounds on tadpole (Lithobates sylvatica) exposure and susceptibility to Ribeiroia ondatrae, based on ecological stoichiometry and community-ecology theory. We predicted direct and indirect effects on key traits of the tadpole host (rates of growth, development and survival), the trematode parasite (production of the cercaria infective stages) and the parasite's snail intermediate host (growth and reproduction). To test these predictions, we conducted a large-scale mesocosm experiment using a natural gradient in the concentrations of nutrients (nitrogen) and toxic secondary compounds (polyphenolics) of nine leaf litter species. To differentiate between effects on exposure vs. susceptibility to infection, we included multiple infection experiments including one with constant per capita exposure. We found that increased litter nitrogen increased tadpole survival, and also increased cercaria production by the snail intermediate hosts, causing opposing effects on tadpole per capita exposure to trematode infection. Increased litter polyphenolics slowed tadpole development, leading to increased infection by increasing both their susceptibility to infection and the length of time they were exposed to parasites. Based on these results, recent shifts in forest composition towards more nitrogen-poor litter species should decrease trematode infection in tadpoles via density- and trait-mediated effects on the snail intermediate hosts. However, these shifts also involve increased abundance of litter species with high polyphenolic levels, which should increase trematode infection via trait-mediated effects on tadpoles. Future studies will be needed to determine the relative strength of these opposing effects in natural wetland communities. [Correction added after online publication on 5 January 2017: wording changed to 'which should increase trematode infection via trait-mediated effects on tadpoles'.].
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Affiliation(s)
| | - Karie A Altman
- Oakland University, 2200 N. Squirrel Rd., Rochester, MI, USA
| | - Keith A Berven
- Oakland University, 2200 N. Squirrel Rd., Rochester, MI, USA
| | - Scott D Tiegs
- Oakland University, 2200 N. Squirrel Rd., Rochester, MI, USA
| | - Thomas R Raffel
- Oakland University, 2200 N. Squirrel Rd., Rochester, MI, USA
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16
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Stoler AB, Berven KA, Raffel TR. Leaf Litter Inhibits Growth of an Amphibian Fungal Pathogen. ECOHEALTH 2016; 13:392-404. [PMID: 26935822 DOI: 10.1007/s10393-016-1106-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/29/2016] [Accepted: 02/09/2016] [Indexed: 06/05/2023]
Abstract
Past studies have found a heterogeneous distribution of the amphibian chytrid fungal pathogen, Batrachochytrium dendrobatidis (Bd). Recent studies have accounted for some of this heterogeneity through a positive association between canopy cover and Bd abundance, which is attributed to the cooling effect of canopy cover. We questioned whether leaf litter inputs that are also associated with canopy cover might also alter Bd growth. Leaf litter inputs exhibit tremendous interspecific chemical variation, and we hypothesized that Bd growth varies with leachate chemistry. We also hypothesized that Bd uses leaf litter as a growth substrate. To test these hypotheses, we conducted laboratory trials in which we exposed cultures of Bd to leachate of 12 temperate leaf litter species at varying dilutions. Using a subset of those 12 litter species, we also exposed Bd to pre-leached litter substrate. We found that exposure to litter leachate and substrate reduced Bd spore and sporangia densities, although there was substantial variation among treatments. In particular, Bd densities were inversely correlated with concentrations of phenolic acids. We conducted a field survey of phenolic concentrations in natural wetlands which verified that the leachate concentrations in our lab study are ecologically relevant. Our study reinforces prior indications that positive associations between canopy cover and Bd abundance are likely mediated by water temperature effects, but this phenomenon might be counteracted by changes in aquatic chemistry from leaf litter inputs.
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Affiliation(s)
- Aaron B Stoler
- Department of Biological Sciences, Oakland University, Rochester, MI, USA.
- 1115 Center for Biotechnology and Integrative Sciences, Department of Biological Sciences, Rensselaer Polytechnic Institute, 110 8th St, Troy, NY, 12180, USA.
| | - Keith A Berven
- Department of Biological Sciences, Oakland University, Rochester, MI, USA
| | - Thomas R Raffel
- Department of Biological Sciences, Oakland University, Rochester, MI, USA
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