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William A Hopkins - One of the best experts on this subject based on the ideXlab platform.
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energetics of metamorphic climax in the Pickerel Frog lithobates palustris
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2009Co-Authors: Sarah A Orlofske, William A HopkinsAbstract:Anuran metamorphosis, the transition from aquatic larvae to terrestrial juveniles, is accompanied by significant morphological, physiological, and behavioral changes. Timing of metamorphosis and final size, which can influence adult fitness, may depend on sufficient energy accumulated during the larval period to support metamorphosis. However, only two species of anurans have been examined for energetic costs of metamorphosis, Rana tigrina and Anaxyrus terrestris. Based on these species, it has been hypothesized that differences in energy expenditure are related to duration of metamorphosis. To compare energetic costs of metamorphosis among species and examine this hypothesis, we quantified the total energy required for metamorphosis of Lithobates palustris tadpoles by measuring oxygen consumption rates over the duration of metamorphic climax using closed-circuit respirometry. Total energy costs for L. palustris were positively related to tadpole mass and duration of metamorphic climax. However, larger tadpoles completed metamorphosis more efficiently because they used proportionally less total energy for metamorphic climax than smaller counterparts. Costs were intermediate to R. tigrina, a larger species with similar metamorphic duration, and A. terrestris, a smaller species with shorter metamorphic climax. The results supported the hypothesis that amphibian species with more slowly developing tadpoles, such as ranids, require more absolute energy for metamorphosis in comparison to more rapidly developing species like bufonids.
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Moderate Echinostoma trivolvis Infection Has No Effects on Physiology and Fitness-Related Traits of Larval Pickerel Frogs (Rana palustris)
The Journal of parasitology, 2009Co-Authors: Sarah A Orlofske, Lisa K. Belden, William A HopkinsAbstract:High intensity infections of Echinostoma trivolvis metacercariae decrease survival and growth of young amphibian larvae. However, in nature, parasites are highly aggregated, which results in a large proportion of the amphibian population being only moderately infected. Survival and growth responses at these more-common, low-infection levels remain poorly studied. Thus, we investigated the effects of moderate Echinostoma trivolvis metacercariae infection (following exposure to 0, 10, 30, or 90 cercariae) on the growth and development of Pickerel Frog (Rana palustris) tadpoles. We measured metabolism to determine whether increased energy expenditure is a potential physiological mechanism underlying previously documented reduced growth. Furthermore, we quantified tadpole intestine size, which can exhibit plasticity in response to changing metabolic demands, and we characterized metacercariae distribution in tadpole kidneys. Metacercariae encysted in the pronephros significantly more than in the mesonephros, but tended to occur equally in right and left kidneys. Two mo post-infection (PI), there were no changes in tadpole survival, development, intestine size, or growth related to metacercariae infection. Similarly, metacercariae did not significantly increase metabolic rates during encystment or at 1 mo PI. Our study demonstrated that modest E. trivolvis infections, representative of a large proportion of the host population, had no detectable effects on fitness-related traits in laboratory isolation from other ecological variables.
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Relative Toxicity of Malathion to Trematode-Infected and Noninfected Rana palustris Tadpoles
Archives of Environmental Contamination and Toxicology, 2008Co-Authors: Sarah A. Budischak, Lisa K. Belden, William A HopkinsAbstract:Amphibian populations around the world are facing threats that include disease and pollution. Although the effect of environmental contaminants on susceptibility to infection has been demonstrated for several amphibian species, to our knowledge, the opposite interaction, infection status affecting contaminant susceptibility, has not been studied. We conducted standard 48-h toxicity tests to compare susceptibility to malathion, a widely used organophosphate insecticide, of uninfected Pickerel Frog ( Rana palustris ) tadpoles and tadpoles infected with two levels (10 or 30 cercariae) of the trematode Echinostoma trivolvis. Trematode encystment rates were high (>90%) in both trematode treatment groups. LC_50 values ranged from 16.5 to 17.4 mg/L, within the range reported for other amphibian species. However, we found no differences in susceptibility to malathion among parasite treatments. Although we detected no effect of parasites on pesticide susceptibility in this system, it is important to investigate this question using other pesticides, parasites, and amphibian hosts before dismissing this potentially threatening interaction.
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Relative Toxicity of Malathion to Trematode-Infected and Noninfected Rana palustris Tadpoles
Archives of environmental contamination and toxicology, 2008Co-Authors: Sarah A. Budischak, Lisa K. Belden, William A HopkinsAbstract:Amphibian populations around the world are facing threats that include disease and pollution. Although the effect of environmental contaminants on susceptibility to infection has been demonstrated for several amphibian species, to our knowledge, the opposite interaction, infection status affecting contaminant susceptibility, has not been studied. We conducted standard 48-h toxicity tests to compare susceptibility to malathion, a widely used organophosphate insecticide, of uninfected Pickerel Frog (Rana palustris) tadpoles and tadpoles infected with two levels (10 or 30 cercariae) of the trematode Echinostoma trivolvis. Trematode encystment rates were high (>90%) in both trematode treatment groups. LC50 values ranged from 16.5 to 17.4 mg/L, within the range reported for other amphibian species. However, we found no differences in susceptibility to malathion among parasite treatments. Although we detected no effect of parasites on pesticide susceptibility in this system, it is important to investigate this question using other pesticides, parasites, and amphibian hosts before dismissing this potentially threatening interaction.
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Effects of malathion on embryonic development and latent susceptibility to trematode parasites in ranid tadpoles.
Environmental toxicology and chemistry, 2008Co-Authors: Sarah A. Budischak, Lisa K. Belden, William A HopkinsAbstract:We investigated the effects of embryonic exposure to the widely used organophosphate malathion (15-600 g/L) on the early development and latent susceptibility of Pickerel Frog (Rana palustris) tadpoles to the trematode parasite Echinostoma trivolvis. The latent effects of contaminant exposure are rarely examined but could have important implications for individual survival and population viability. Malathion decreased hatching success by 6.5% and viability rates by 17% at 600 g/L, which is a lower concentration than previously documented for anuran embryos. Incidence of malformations increased from 0.5% in controls to 11.2% in the 600-g/L malathion treatment. The primary malformations documented in the two highest pesticide concentrations were ventralization and axial shortening. After seven weeks of development in water with no malathion, tadpoles previously exposed as embryos for only 96 h to 60 and 600 g/L malathion suffered increased parasite encystment rates when compared to controls. Our research identifies embryonic development as a sensitive window for establishing latent susceptibility to infection in later developmental stages.
Christopher Shaw - One of the best experts on this subject based on the ideXlab platform.
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Skin bradykinin-related peptides (BRPs) and their biosynthetic precursors (kininogens): comparisons between various taxa of Chinese and North American ranid Frogs.
Peptides, 2007Co-Authors: Y.t. Sin, Mei Zhou, Tianbao Chen, Lei Wang, Wei Chen, Brian R. Walker, Christopher ShawAbstract:Bradykinins and related peptides (BRPs) occur in the defensive skin secretions of many amphibians. Here we report the structures of BRPs and their corresponding biosynthetic precursor cDNAs from the Chinese brown Frog, Rana chensinensis, and the North American leopard Frog, Lithobates pipiens. R. chensinensis skin contained four transcripts each encoding a different kininogen whose organizations and spectrum of encoded BRPs were similar to those reported for the Pickerel Frog, Lithobates palustris. In contrast, from L. pipiens, a single skin kininogen was cloned whose structural organization and spectrum of mature BRPs were similar to those reported for the Chinese piebald odorous Frog, Huia schmackeri. These data also implied that the endogenous precursor processing proteases in each species pair have identical site-directed specificities, which in part may be dictated by the primary structures of encoded BRPs. Thus the spectra of skin BRPs and the organization of their biosynthetic precursors are not consistent with recent taxonomy. The natural selective pressures that mould the primary structures of amphibian skin secretion peptides are thought to be related to the spectrum of predators encountered within their habitats. Thus similarities and differences in skin bradykinins may be reflective of predator spectra rather than indicative of species relatedness.
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The complex array of bradykinin-related peptides (BRPs) in the peptidome of Pickerel Frog (Rana palustris) skin secretion is the product of transcriptional economy
Peptides, 2007Co-Authors: Cian Michael Mccrudden, Brian Walker, Mei Zhou, Tianbao Chen, Martin O'rourke, Christopher ShawAbstract:Previous peptidomic analyses of the defensive skin secretion from the North American Pickerel Frog, Rana palustris, have established the presence of canonical bradykinin and multiple bradykinin-related peptides (BRPs). As a consequence of the multiplicity of peptides identified and their diverse primary structures, it was speculated that they must represent the products of expression of multiple genes. Here, we present unequivocal evidence that the majority of BRPs (11/13) identified in skin secretion by the peptidomic approach can be generated by differential site-specific protease cleavage from a single common precursor of 321 amino acid residues, named skin kininogen 1, whose primary structure was deduced from cloned skin secretion-derived cDNA. The organization of skin kininogen 1 consists of a hydrophobic signal peptide followed by eight non-identical domains each encoding a single copy of either canonical bradykinin or a BRP. Two additional splice variants, encoding precursors of 233 (skin kininogen 2) or 189 amino acid residues (skin kininogen 3), were also cloned and were found to lack BRP-encoding domains 5 and 6 or 4, 5 and 6, respectively. Thus, generation of peptidome diversity in amphibian defensive skin secretions can be achieved in part by differential protease cleavage of relatively large and multiple-encoding domain precursors reflecting a high degree of transcriptional economy.
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The Chinese bamboo leaf odorous Frog (Rana (Odorrana) versabilis) and North American Rana Frogs share the same families of skin antimicrobial peptides.
Peptides, 2006Co-Authors: Pingfan Rao, Christopher ShawAbstract:Abstract The Chinese bamboo leaf odorous Frog ( Rana ( Odorrana ) versabilis ) and the North American Pickerel Frog ( Rana palustris ) occupy different ecological niches on two different continents with no overlap in geographical distribution. R. palustris skin secretions contain a formidable array of antimicrobial peptides including homologs of brevinin-1, esculentin-1, esculentin-2, ranatuerin-2, a temporin and a family of peptides considered of unique structural attributes when isolated, palustrins 1–3. Here we describe the structures of mature peptides and precursors of eight putative antimicrobial peptides from the skin secretion of the Chinese bamboo leaf odorous Frog ( Rana ( Odorrana ) versabilis ). Each peptide represents a structural homolog of respective peptide families isolated from R. palustris , including two peptides identical in primary structure to palustrin 1c and palustrin 3b. Additionally, two peptides were found to be structural homologs of ranatuerin 2B and ranatuerin 2P from the closely-related North American species, Rana berlandieri (the Rio Grande leopard Frog) and Rana pipiens (the Northern leopard Frog), respectively. Both palustrins and ranatuerins have hitherto been considered unique to North American ranid Frogs. The use of primary structures of amphibian skin antimicrobial peptides is thus questionable as a taxonomic device or alternatively, the micro-evolution and/or ancestry of ranid Frogs is more highly complex than previously thought.
Sarah A. Budischak - One of the best experts on this subject based on the ideXlab platform.
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Relative Toxicity of Malathion to Trematode-Infected and Noninfected Rana palustris Tadpoles
Archives of Environmental Contamination and Toxicology, 2008Co-Authors: Sarah A. Budischak, Lisa K. Belden, William A HopkinsAbstract:Amphibian populations around the world are facing threats that include disease and pollution. Although the effect of environmental contaminants on susceptibility to infection has been demonstrated for several amphibian species, to our knowledge, the opposite interaction, infection status affecting contaminant susceptibility, has not been studied. We conducted standard 48-h toxicity tests to compare susceptibility to malathion, a widely used organophosphate insecticide, of uninfected Pickerel Frog ( Rana palustris ) tadpoles and tadpoles infected with two levels (10 or 30 cercariae) of the trematode Echinostoma trivolvis. Trematode encystment rates were high (>90%) in both trematode treatment groups. LC_50 values ranged from 16.5 to 17.4 mg/L, within the range reported for other amphibian species. However, we found no differences in susceptibility to malathion among parasite treatments. Although we detected no effect of parasites on pesticide susceptibility in this system, it is important to investigate this question using other pesticides, parasites, and amphibian hosts before dismissing this potentially threatening interaction.
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Relative Toxicity of Malathion to Trematode-Infected and Noninfected Rana palustris Tadpoles
Archives of environmental contamination and toxicology, 2008Co-Authors: Sarah A. Budischak, Lisa K. Belden, William A HopkinsAbstract:Amphibian populations around the world are facing threats that include disease and pollution. Although the effect of environmental contaminants on susceptibility to infection has been demonstrated for several amphibian species, to our knowledge, the opposite interaction, infection status affecting contaminant susceptibility, has not been studied. We conducted standard 48-h toxicity tests to compare susceptibility to malathion, a widely used organophosphate insecticide, of uninfected Pickerel Frog (Rana palustris) tadpoles and tadpoles infected with two levels (10 or 30 cercariae) of the trematode Echinostoma trivolvis. Trematode encystment rates were high (>90%) in both trematode treatment groups. LC50 values ranged from 16.5 to 17.4 mg/L, within the range reported for other amphibian species. However, we found no differences in susceptibility to malathion among parasite treatments. Although we detected no effect of parasites on pesticide susceptibility in this system, it is important to investigate this question using other pesticides, parasites, and amphibian hosts before dismissing this potentially threatening interaction.
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Effects of malathion on embryonic development and latent susceptibility to trematode parasites in ranid tadpoles.
Environmental toxicology and chemistry, 2008Co-Authors: Sarah A. Budischak, Lisa K. Belden, William A HopkinsAbstract:We investigated the effects of embryonic exposure to the widely used organophosphate malathion (15-600 g/L) on the early development and latent susceptibility of Pickerel Frog (Rana palustris) tadpoles to the trematode parasite Echinostoma trivolvis. The latent effects of contaminant exposure are rarely examined but could have important implications for individual survival and population viability. Malathion decreased hatching success by 6.5% and viability rates by 17% at 600 g/L, which is a lower concentration than previously documented for anuran embryos. Incidence of malformations increased from 0.5% in controls to 11.2% in the 600-g/L malathion treatment. The primary malformations documented in the two highest pesticide concentrations were ventralization and axial shortening. After seven weeks of development in water with no malathion, tadpoles previously exposed as embryos for only 96 h to 60 and 600 g/L malathion suffered increased parasite encystment rates when compared to controls. Our research identifies embryonic development as a sensitive window for establishing latent susceptibility to infection in later developmental stages.
Tianbao Chen - One of the best experts on this subject based on the ideXlab platform.
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Identification and molecular cloning of novel antimicrobial peptides from skin secretions of the Chinese bamboo leaf odorous Frog (Odorrana versabilis) and the North American Pickerel Frog (Rana palustris)
Journal of Traditional Chinese Medical Sciences, 2017Co-Authors: Runxin Qiao, Tianbao ChenAbstract:Abstract Objective Amphibian skin secretions are an abundant source of bioactive peptides, some of which could be developed as candidate drugs. Among these natural peptides, cytolytic peptides have attracted the most attention given that they might replace conventional antibiotics and help deal with the problem of microbial resistance. This study discovered two bioactive peptides, Brevinin-1-PLr and Nigrocin-2-OV, from two species Frogs, the Chinese bamboo leaf odorous Frog ( Odorrana versabilis ) and the North American Pickerel Frog ( Rana palustris ), respectively. Their antimicrobial, anticancer and hemolytic activities were also investigated. Methods cDNA sequences encoding peptides were cloned from cDNA libraries constructed from the lyophilized secretions of the Chinese bamboo leaf odorous Frog and the North American Pickerel Frog. By reversed-phase HPLC and MS/MS fragmentation sequencing, the encoded novel peptides, named Nigrocin-2-OV and Brevinin-1-PLr, were identified in skin secretions and their structures were confirmed. Replicates of both peptides were produced through solid phase peptide synthesis. Their antimicrobial and anticancer activity was studied against three types of microorganisms ( Staphylococcus aureus , Candida albicans , and Escherichia coli ) and five cancer cell lines (NCI-H157, PC-3, MDA-MB-435s, MCF-7, and U251MG). Their hemolytic activity was investigated using whole horse blood. Results In this research, cDNA sequences encoding two novel 24-mer peptides were cloned from cDNA libraries constructed from the lyophilized skin secretions of the Chinese bamboo leaf odorous Frog and the North American Pickerel Frog. Both of the peptides had the strongest inhibitory effect against C. albicans , and IC 50 values against five cancer cell lines were all under 6 μM. Conclusions Nigrocin-2-OV and Brevinin-1-PLr had the strong ability to inhibit the proliferation of studied microorganisms and tumor cell lines, with slight hemolytic activity. Compared with Brevinin-1-PLr, Nigrocin-2-OV exhibited higher antimicrobial and anticancer activity but slightly higher hemolytic activity.
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Skin bradykinin-related peptides (BRPs) and their biosynthetic precursors (kininogens): comparisons between various taxa of Chinese and North American ranid Frogs.
Peptides, 2007Co-Authors: Y.t. Sin, Mei Zhou, Tianbao Chen, Lei Wang, Wei Chen, Brian R. Walker, Christopher ShawAbstract:Bradykinins and related peptides (BRPs) occur in the defensive skin secretions of many amphibians. Here we report the structures of BRPs and their corresponding biosynthetic precursor cDNAs from the Chinese brown Frog, Rana chensinensis, and the North American leopard Frog, Lithobates pipiens. R. chensinensis skin contained four transcripts each encoding a different kininogen whose organizations and spectrum of encoded BRPs were similar to those reported for the Pickerel Frog, Lithobates palustris. In contrast, from L. pipiens, a single skin kininogen was cloned whose structural organization and spectrum of mature BRPs were similar to those reported for the Chinese piebald odorous Frog, Huia schmackeri. These data also implied that the endogenous precursor processing proteases in each species pair have identical site-directed specificities, which in part may be dictated by the primary structures of encoded BRPs. Thus the spectra of skin BRPs and the organization of their biosynthetic precursors are not consistent with recent taxonomy. The natural selective pressures that mould the primary structures of amphibian skin secretion peptides are thought to be related to the spectrum of predators encountered within their habitats. Thus similarities and differences in skin bradykinins may be reflective of predator spectra rather than indicative of species relatedness.
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rapid identification of precursor cdnas encoding five structural classes of antimicrobial peptides from Pickerel Frog rana palustris skin secretion by single step shotgun cloning
Peptides, 2007Co-Authors: Mei Zhou, Brian Walker, Tianbao Chen, Lei Wang, D E Owens, C. ShawAbstract:The skin secretion of the North American Pickerel Frog (Rana palustris) has long been known to have pronounced noxious/toxic properties and to be highly effective in defence against predators and against other sympatric amphibians. As it consists largely of a complex mixture of peptides, it has been subjected to systematic peptidomic study but there has been little focus on molecular cloning of peptide-encoding cDNAs and by deduction, the biosynthetic precursors that they encode. Here, we demonstrate that the cDNAs encoding the five major structural families of antimicrobial peptides can be elucidated by a single step "shotgun" cloning approach using a cDNA library constructed from the source material of the peptidomic studies--the defensive skin secretion itself. Using a degenerate primer pool designed to a highly conserved nucleic acid sequence 5' to the initiation codon of known antimicrobial peptide precursor transcripts, we amplified cDNA sequences representing five major classes of antimicrobial peptides, such as esculentins, brevinins, ranatuerins, palustrins and temporins. Bioinformatic comparisons of precursor open-reading frames and nucleic acid sequences revealed high degrees of structural similarities between analogous peptides of R. palustris and the Chinese bamboo odorous Frog, Rana versabilis. This approach thus constitutes a robust technique that can be used either alone or ideally, in parallel with peptidomic analysis of skin secretion, to rapidly extract primary structural information on amphibian skin secretion peptides and their biosynthetic precursors.
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The complex array of bradykinin-related peptides (BRPs) in the peptidome of Pickerel Frog (Rana palustris) skin secretion is the product of transcriptional economy
Peptides, 2007Co-Authors: Cian Michael Mccrudden, Brian Walker, Mei Zhou, Tianbao Chen, Martin O'rourke, Christopher ShawAbstract:Previous peptidomic analyses of the defensive skin secretion from the North American Pickerel Frog, Rana palustris, have established the presence of canonical bradykinin and multiple bradykinin-related peptides (BRPs). As a consequence of the multiplicity of peptides identified and their diverse primary structures, it was speculated that they must represent the products of expression of multiple genes. Here, we present unequivocal evidence that the majority of BRPs (11/13) identified in skin secretion by the peptidomic approach can be generated by differential site-specific protease cleavage from a single common precursor of 321 amino acid residues, named skin kininogen 1, whose primary structure was deduced from cloned skin secretion-derived cDNA. The organization of skin kininogen 1 consists of a hydrophobic signal peptide followed by eight non-identical domains each encoding a single copy of either canonical bradykinin or a BRP. Two additional splice variants, encoding precursors of 233 (skin kininogen 2) or 189 amino acid residues (skin kininogen 3), were also cloned and were found to lack BRP-encoding domains 5 and 6 or 4, 5 and 6, respectively. Thus, generation of peptidome diversity in amphibian defensive skin secretions can be achieved in part by differential protease cleavage of relatively large and multiple-encoding domain precursors reflecting a high degree of transcriptional economy.
Lisa K. Belden - One of the best experts on this subject based on the ideXlab platform.
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Moderate Echinostoma trivolvis Infection Has No Effects on Physiology and Fitness-Related Traits of Larval Pickerel Frogs (Rana palustris)
The Journal of parasitology, 2009Co-Authors: Sarah A Orlofske, Lisa K. Belden, William A HopkinsAbstract:High intensity infections of Echinostoma trivolvis metacercariae decrease survival and growth of young amphibian larvae. However, in nature, parasites are highly aggregated, which results in a large proportion of the amphibian population being only moderately infected. Survival and growth responses at these more-common, low-infection levels remain poorly studied. Thus, we investigated the effects of moderate Echinostoma trivolvis metacercariae infection (following exposure to 0, 10, 30, or 90 cercariae) on the growth and development of Pickerel Frog (Rana palustris) tadpoles. We measured metabolism to determine whether increased energy expenditure is a potential physiological mechanism underlying previously documented reduced growth. Furthermore, we quantified tadpole intestine size, which can exhibit plasticity in response to changing metabolic demands, and we characterized metacercariae distribution in tadpole kidneys. Metacercariae encysted in the pronephros significantly more than in the mesonephros, but tended to occur equally in right and left kidneys. Two mo post-infection (PI), there were no changes in tadpole survival, development, intestine size, or growth related to metacercariae infection. Similarly, metacercariae did not significantly increase metabolic rates during encystment or at 1 mo PI. Our study demonstrated that modest E. trivolvis infections, representative of a large proportion of the host population, had no detectable effects on fitness-related traits in laboratory isolation from other ecological variables.
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Relative Toxicity of Malathion to Trematode-Infected and Noninfected Rana palustris Tadpoles
Archives of Environmental Contamination and Toxicology, 2008Co-Authors: Sarah A. Budischak, Lisa K. Belden, William A HopkinsAbstract:Amphibian populations around the world are facing threats that include disease and pollution. Although the effect of environmental contaminants on susceptibility to infection has been demonstrated for several amphibian species, to our knowledge, the opposite interaction, infection status affecting contaminant susceptibility, has not been studied. We conducted standard 48-h toxicity tests to compare susceptibility to malathion, a widely used organophosphate insecticide, of uninfected Pickerel Frog ( Rana palustris ) tadpoles and tadpoles infected with two levels (10 or 30 cercariae) of the trematode Echinostoma trivolvis. Trematode encystment rates were high (>90%) in both trematode treatment groups. LC_50 values ranged from 16.5 to 17.4 mg/L, within the range reported for other amphibian species. However, we found no differences in susceptibility to malathion among parasite treatments. Although we detected no effect of parasites on pesticide susceptibility in this system, it is important to investigate this question using other pesticides, parasites, and amphibian hosts before dismissing this potentially threatening interaction.
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Relative Toxicity of Malathion to Trematode-Infected and Noninfected Rana palustris Tadpoles
Archives of environmental contamination and toxicology, 2008Co-Authors: Sarah A. Budischak, Lisa K. Belden, William A HopkinsAbstract:Amphibian populations around the world are facing threats that include disease and pollution. Although the effect of environmental contaminants on susceptibility to infection has been demonstrated for several amphibian species, to our knowledge, the opposite interaction, infection status affecting contaminant susceptibility, has not been studied. We conducted standard 48-h toxicity tests to compare susceptibility to malathion, a widely used organophosphate insecticide, of uninfected Pickerel Frog (Rana palustris) tadpoles and tadpoles infected with two levels (10 or 30 cercariae) of the trematode Echinostoma trivolvis. Trematode encystment rates were high (>90%) in both trematode treatment groups. LC50 values ranged from 16.5 to 17.4 mg/L, within the range reported for other amphibian species. However, we found no differences in susceptibility to malathion among parasite treatments. Although we detected no effect of parasites on pesticide susceptibility in this system, it is important to investigate this question using other pesticides, parasites, and amphibian hosts before dismissing this potentially threatening interaction.
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Effects of malathion on embryonic development and latent susceptibility to trematode parasites in ranid tadpoles.
Environmental toxicology and chemistry, 2008Co-Authors: Sarah A. Budischak, Lisa K. Belden, William A HopkinsAbstract:We investigated the effects of embryonic exposure to the widely used organophosphate malathion (15-600 g/L) on the early development and latent susceptibility of Pickerel Frog (Rana palustris) tadpoles to the trematode parasite Echinostoma trivolvis. The latent effects of contaminant exposure are rarely examined but could have important implications for individual survival and population viability. Malathion decreased hatching success by 6.5% and viability rates by 17% at 600 g/L, which is a lower concentration than previously documented for anuran embryos. Incidence of malformations increased from 0.5% in controls to 11.2% in the 600-g/L malathion treatment. The primary malformations documented in the two highest pesticide concentrations were ventralization and axial shortening. After seven weeks of development in water with no malathion, tadpoles previously exposed as embryos for only 96 h to 60 and 600 g/L malathion suffered increased parasite encystment rates when compared to controls. Our research identifies embryonic development as a sensitive window for establishing latent susceptibility to infection in later developmental stages.