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Shuman-Goodier ME, Singleton GR, Forsman AM, Hines S, Christodoulides N, Daniels KD, Propper CR. Developmental assays using invasive cane toads, Rhinella marina, reveal safety concerns of a common formulation of the rice herbicide, butachlor. Environ Pollut 2021; 272:115955. [PMID: 33221087 PMCID: PMC7878340 DOI: 10.1016/j.envpol.2020.115955] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 06/11/2023]
Abstract
Identifying the adverse impacts of pesticide exposure is essential to guide regulations that are protective of wildlife and human health. Within rice ecosystems, amphibians are valuable indicators because pesticide applications coincide with sensitive reproductive and developmental life stages. We conducted two experiments using wild cane toads (Rhinella marina) to test 1) whether environmentally relevant exposure to a commercial formulation of butachlor, an acetanilide herbicide used extensively in rice, affects amphibian development and 2) whether cane toad tadpoles are capable of acclimatizing to sub-lethal exposure. First, we exposed wild cane toads to 0.002, 0.02, or 0.2 mg/L of butachlor (Machete EC), during distinct development stages (as eggs and hatchlings, as tadpoles, or continuously) for 12 days. Next, we exposed a subset of animals from the first experiment to a second, lethal concentration and examined survivorship. We found that cane toads exposed to butachlor developed slower and weighed less than controls, and that development of the thyroid gland was affected: exposed individuals had smaller thyroid glands and thyrocyte cells, and more individual follicles. Analyses of the transcriptome revealed that butachlor exposure resulted in downregulation of transcripts related to metabolic processes, anatomic structure development, immune system function, and response to stress. Last, we observed evidence of acclimatization, where animals exposed to butachlor early in life performed better than naïve animals during a second exposure. Our findings indicate that the commercial formulation of butachlor, Machete EC, causes thyroid endocrine disruption in vertebrates, and suggest that exposure in lowland irrigated rice fields presents a concern for wildlife and human health. Furthermore, we establish that developmental assays with cane toads can be used to screen for adverse effects of pesticides in rice fields.
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Affiliation(s)
- Molly E Shuman-Goodier
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86001, USA; International Rice Research Institute, Los Baños, Philippines.
| | - Grant R Singleton
- International Rice Research Institute, Los Baños, Philippines; Natural Resource Institute, University of Greenwich, Chatham Maritime, Kent, UK
| | - Anna M Forsman
- Department of Biology, University of Central Florida, Orlando, FL, 32816-2368, USA; Genomics and Bioinformatics Cluster, University of Central Florida, Orlando, FL, 32816-2368, USA
| | - Shyann Hines
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86001, USA
| | | | - Kevin D Daniels
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - Catherine R Propper
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86001, USA
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Rivory P, Brown G, Shilton C, Shine R, Šlapeta J. Apparent lack of spill-over of parasites from an invasive anuran: PCR detects Entamoeba in cane toads ( Rhinella marina) but not in sympatric Australian native frogs. Int J Parasitol Parasites Wildl 2020; 12:207-213. [PMID: 32685367 PMCID: PMC7355385 DOI: 10.1016/j.ijppaw.2020.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 06/30/2020] [Accepted: 06/30/2020] [Indexed: 11/12/2022]
Abstract
The recent detection of a novel amoebozoan parasite (Entamoeba sp. CT1) killing invasive cane toads (Rhinella marina) in tropical Australia raises concerns of potential spill-over into native anuran populations. Considering the vulnerability of anuran communities globally, Entamoeba sp. CT1 may pose a serious threat to anuran biodiversity. Through PCR-based detection and molecular identification, we investigated the prevalence of Entamoeba spp. in the faeces and colon tissue of cane toads (Rhinella marina) and eleven native Australian frog species from a single locality in the Northern Territory. No Entamoeba DNA was detected in samples of native frog faeces (N = 57) or colons (N = 17). Entamoeba DNA was detected in 24% of 45 cane toads (95%CI 14.08–38.82). Both E. ranarum and Entamoeba sp. CT1 were present in cane toads. The failure of faecal samples to indicate Entamoeba spp. in infected cane toads may be due to cysts in faeces being shed intermittently, degraded before analysis, or impervious to lysis prior to DNA isolation. Our results suggest that native frogs do not carry the pathogen in an area where 20–30% of cane toads are infected with Entamoeba sp. CT1. We demonstrate the importance of recognising PCR inhibition prior to molecular diagnostics, and the apparent inadequacy of faecal samples for the detection of Entamoeba spp. in anurans. Entamoeba spp. were detected in cane toads, but not in faeces or colons of native frogs. PCR inhibition of anuran faecal samples. Additional purification, the presence of inhibition was reduced.
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Affiliation(s)
- Phoebe Rivory
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, New South Wales, 2006, Australia
| | - Gregory Brown
- Department of Biological Sciences, Faculty of Science and Engineering, Macquarie University, New South Wales, 2109, Australia
| | - Cathy Shilton
- Berrimah Veterinary Laboratory, Northern Territory Government, GPO Box 3000, Darwin, Northern Territory, 0801, Australia
| | - Richard Shine
- Department of Biological Sciences, Faculty of Science and Engineering, Macquarie University, New South Wales, 2109, Australia
| | - Jan Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, New South Wales, 2006, Australia
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Gardner ST, Assis VR, Smith KM, Appel AG, Mendonça MT. Innate immunity of Florida cane toads: how dispersal has affected physiological responses to LPS. J Comp Physiol B 2020; 190:317-327. [PMID: 32189063 DOI: 10.1007/s00360-020-01272-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 02/24/2020] [Accepted: 03/02/2020] [Indexed: 12/21/2022]
Abstract
Physiological tradeoffs occur in organisms coping with their environments, which are likely to increase as populations reach peripheries of established ranges. Invasive species offer opportunities to study tradeoffs that occur, with many hypotheses focusing on how immune responses vary during dispersal. The cane toad (Rhinella marina) is a well-known invasive species. Populations near the expanding edge of the Australian invasion have altered immune responses compared to toads from longer-established core populations, although this has not been well-documented for Florida populations. In this study, cane toads from a northern edge [New Port Richey (NPR)] and southern core (Miami) population in Florida were collected and injected with lipopolysaccharide (LPS) to compare immune responses. Core population individuals injected with LPS showed greater metabolic increases compared to their baseline rates that were higher compared to those from the edge population. In addition, LPS-injected core individuals had different circulating leukocyte profiles compared to saline-injected cane toads while edge individuals did not. There was a significant interaction between plasma bacteria-killing capability (BKA) and treatment, such that BKA decreased with time in saline compared to LPS-injected individuals, and saline-injected toads from the edge population had lower BKA compared to LPS-injected edge toads at 20 h post-injection. There was also a significant interaction between location and time on circulating corticosterone (CORT) levels following injections with saline or LPS, with CORT decreasing more with time in core population toads. The differential CORT response indicates that differential stress responses contribute to the tradeoffs observed with immunity and dispersal.
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Affiliation(s)
- Steven T Gardner
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, 350 South College St, Auburn, AL, 36849, USA.
| | - Vania R Assis
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua Do Matão, trav. 14, 101, São Paulo, SP, 05508-900, Brazil
| | - Kyra M Smith
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, 350 South College St, Auburn, AL, 36849, USA
| | - Arthur G Appel
- Department of Entomology and Plant Pathology, Auburn University, 301 Funchess Hall, 350 South College St, Auburn, AL, 36849, USA
| | - Mary T Mendonça
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, 350 South College St, Auburn, AL, 36849, USA
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4
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Cox SM, Gillis GB. The integration of sensory feedback in the modulation of anuran landing preparation. J Exp Biol 2020; 223:jeb214908. [PMID: 31915199 DOI: 10.1242/jeb.214908] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 01/06/2020] [Indexed: 12/12/2022]
Abstract
Controlled landing requires preparation. Mammals and bipedal birds vary how they prepare for landing by predicting the timing and magnitude of impact from the integration of visual and non-visual information. Here, we explore how the cane toad Rhinella marina - an animal that moves primarily through hopping - integrates sensory information to modulate landing preparation. Earlier work suggests that toads may modulate landing preparation using predictions of impact timing and/or magnitude based on non-visual sensory feedback during takeoff rather than visual cues about the landing itself. We disentangled takeoff and landing conditions by hopping toads off platforms of different heights while measuring electromyographic (EMG) activity of an elbow extensor (m. anconeus) and capturing high-speed images to quantify whole body and forelimb kinematics. This enabled us to test how toads integrate visual and non-visual information in landing preparation. We asked two questions: (1) when they conflict, do toads correlate landing preparation with takeoff or landing conditions? And (2) for hops with the same takeoff conditions, does visual information alter the timing of landing preparation? We found that takeoff conditions are a better predictor of the onset of landing preparation than landing conditions, but that visual information is not ignored. When hopping off higher platforms, toads start to prepare for landing later when takeoff conditions are invariant. This suggests that, unlike mammals, toads prioritize non-visual sensory feedback about takeoff conditions to coordinate landing, but that they do integrate visual information to fine-tune landing preparation.
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Affiliation(s)
- Suzanne M Cox
- Organismic and Evolutionary Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
| | - Gary B Gillis
- Department of Biology, Mount Holyoke College, Hadley, MA 01075, USA
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Niebuhr CN, Jarvi SI, Kaluna L, Torres Fischer BL, Deane AR, Leinbach IL, Siers SR. Occurrence of Rat Lungworm ( Angiostrongylus cantonensis) in Invasive Coqui Frogs ( Eleutherodactylus coqui) and Other Hosts in Hawaii, USA. J Wildl Dis 2020; 56:203-207. [PMID: 31295084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The rat lungworm (Angiostrongylus cantonensis) has emerged as an important human and animal health concern in Hawaii, US. Although the life cycle of the parasite requires both rat and gastropod hosts, other animals acting as paratenic hosts, such as frogs and centipedes, have been identified as sources of infection. We investigated the occurrence of rat lungworm infections in potential paratenic hosts in Hawaii to provide information on how they might be involved in transmission of angiostrongyliasis. We confirmed the presence of rat lungworm in 87% (21/24) of introduced Puerto Rican coqui frogs (Eleutherodactylus coqui) in Hilo, Hawaii, by real-time PCR. Additionally, four Cuban greenhouse frogs (Eleutherodactylus planirostris), two cane toads (Rhinella marina), and three centipedes (Scolopendra subspinipes) were found to be infected. In the frogs and toads, multiple tissue types were positive, including stomach and intestine, muscle, liver, heart, and brain, indicating larval migration. We identified rat lungworm infections in frogs, toads, and centipedes in Hawaii and highlighted the lack of knowledge of the role paratenic hosts may be playing in the transmission and life cycle maintenance of rat lungworm in Hawaii.
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Affiliation(s)
- Chris N Niebuhr
- US Department of Agriculture, Animal and Plant Health Inspection Service, National Wildlife Research Center, Hawaii Field Station, PO Box 10880, Hilo, Hawaii 96721, USA
| | - Susan I Jarvi
- Department of Pharmaceutical Science, Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, 200 W Kawili Street, Hilo, Hawaii 96720, USA
| | - Lisa Kaluna
- Department of Pharmaceutical Science, Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, 200 W Kawili Street, Hilo, Hawaii 96720, USA
| | - Bruce L Torres Fischer
- Department of Pharmaceutical Science, Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, 200 W Kawili Street, Hilo, Hawaii 96720, USA
| | - Ashley R Deane
- Department of Psychology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Israel L Leinbach
- US Department of Agriculture, Animal and Plant Health Inspection Service, National Wildlife Research Center, Hawaii Field Station, PO Box 10880, Hilo, Hawaii 96721, USA
| | - Shane R Siers
- US Department of Agriculture, Animal and Plant Health Inspection Service, National Wildlife Research Center, Hawaii Field Station, PO Box 10880, Hilo, Hawaii 96721, USA
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Bessa-Silva A, Vallinoto M, Sampaio I, Flores-Villela OA, Smith EN, Sequeira F. The roles of vicariance and dispersal in the differentiation of two species of the Rhinella marina species complex. Mol Phylogenet Evol 2019; 145:106723. [PMID: 31891757 DOI: 10.1016/j.ympev.2019.106723] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 12/23/2019] [Accepted: 12/23/2019] [Indexed: 11/19/2022]
Abstract
The high levels of Neotropical biodiversity are commonly associated with the intense Neogene-Quaternary geological events and climate dynamics. Here, we investigate the evolutionary history of two species of Neotropical closely related amphibians (R. horribilis and R. marina). We combine published data with new mitochondrial DNA sequences and multiple nuclear markers, including 12 microsatellites. The phylogenetic analyses showed support for grouping the samples in two main clades; R. horribilis (Central America and Mexico) and R. marina (South America east of the Andes). However, the phylogenetic inferences also show an evident mito-nuclear discordance. We use Approximate Bayesian Computation (ABC) to test the role of different events in the diversification between the two groups recovered. We found that both species were affected primarily by a recent Pleistocene divergence, which was similar to the divergence estimate revealed by the Isolation-with-Migration model, under persistent bidirectional gene flow through time. We provide the first evidence that R. horribilis is differentiated from the South American R. marina at the nuclear level supporting the taxonomic status of R. horribilis, which has been controversial for more than a century.
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Affiliation(s)
- Adam Bessa-Silva
- Laboratório de Evolução (LEVO), Instituto de Estudos Costeiros (IECOS), Universidade Federal do Pará, Campus de Bragança, 68 600-000 Pará, Brazil; CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus Agrário de Vairão, Universidade do Porto, 4485-661 Vairão, Portugal
| | - Marcelo Vallinoto
- Laboratório de Evolução (LEVO), Instituto de Estudos Costeiros (IECOS), Universidade Federal do Pará, Campus de Bragança, 68 600-000 Pará, Brazil; CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus Agrário de Vairão, Universidade do Porto, 4485-661 Vairão, Portugal.
| | - Iracilda Sampaio
- Laboratório de Evolução (LEVO), Instituto de Estudos Costeiros (IECOS), Universidade Federal do Pará, Campus de Bragança, 68 600-000 Pará, Brazil
| | - Oscar A Flores-Villela
- Museo de Zoología, Department of Evolutionary Biology, Facultad de Ciencias, Universidad Nacional Autónoma de México, External Circuit of Ciudad Universitaria, Mexico City 04510, Mexico
| | - Eric N Smith
- Department of Biology, The University of Texas at Arlington, Arlington, TX, USA; The Amphibian and Reptile Diversity Research Center, University of Texas at Arlington, Arlington, TX, USA
| | - Fernando Sequeira
- CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus Agrário de Vairão, Universidade do Porto, 4485-661 Vairão, Portugal
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Gardner S, Assis VR, Zhao H, Gomes FR, Peatman E, Mendonça MT. Differential gene expression to an LPS challenge in relation to exogenous corticosterone in the invasive cane toad (Rhinella marina). Dev Comp Immunol 2018; 88:114-123. [PMID: 30030104 DOI: 10.1016/j.dci.2018.07.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 07/16/2018] [Accepted: 07/16/2018] [Indexed: 06/08/2023]
Abstract
The cane toad (Rhinella marina) is an invasive amphibian in several parts of the world. Much of the research performed on assessing the dispersal potential of invasive species has focused immunity. Invaders are predicted to rely less on pro-inflammatory immunity, allowing them to allocate energy to dispersal. Elevated stress may play a role in regulation of immune responses used by invasive species. RNA sequencing of spleen tissue from cane toads subjected to an acute LPS challenge revealed genes coding for cytokines involved in typical innate responses such as phagocytic cell recruitment, extravasation, inflammation, and lymphocyte differentiation were significantly upregulated, while toads receiving transdermal application of corticosterone in addition to an LPS injection showed downregulation of genes involved with cell mediated immunity. These results indicate hormonal changes associated with acute stress may alter investment into mounting cell-mediated or humoral responses while allowing for prolonged phagocytic innate responses in this invasive species.
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Affiliation(s)
- Steven Gardner
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, 350 South College St, Auburn, AL 36849, USA.
| | - Vania Regina Assis
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, 05508-900, São Paulo, SP, Brazil.
| | - Honggang Zhao
- School of Fisheries, Aquaculture, and Aquatic Sciences, 377 CASIC Bldg, Auburn University, Auburn, AL 36849, USA.
| | - Fernando Ribeiro Gomes
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, 05508-900, São Paulo, SP, Brazil.
| | - Eric Peatman
- School of Fisheries, Aquaculture, and Aquatic Sciences, 377 CASIC Bldg, Auburn University, Auburn, AL 36849, USA.
| | - Mary T Mendonça
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, 350 South College St, Auburn, AL 36849, USA.
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Selechnik D, West AJ, Brown GP, Fanson KV, Addison B, Rollins LA, Shine R. Effects of invasion history on physiological responses to immune system activation in invasive Australian cane toads. PeerJ 2017; 5:e3856. [PMID: 29018604 PMCID: PMC5633027 DOI: 10.7717/peerj.3856] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 09/06/2017] [Indexed: 12/12/2022] Open
Abstract
The cane toad (Rhinella marina) has undergone rapid evolution during its invasion of tropical Australia. Toads from invasion front populations (in Western Australia) have been reported to exhibit a stronger baseline phagocytic immune response than do conspecifics from range core populations (in Queensland). To explore this difference, we injected wild-caught toads from both areas with the experimental antigen lipopolysaccharide (LPS, to mimic bacterial infection) and measured whole-blood phagocytosis. Because the hypothalamic-pituitary-adrenal axis is stimulated by infection (and may influence immune responses), we measured glucocorticoid response through urinary corticosterone levels. Relative to injection of a control (phosphate-buffered saline), LPS injection increased both phagocytosis and the proportion of neutrophils in the blood. However, responses were similar in toads from both populations. This null result may reflect the ubiquity of bacterial risks across the toad’s invaded range; utilization of this immune pathway may not have altered during the process of invasion. LPS injection also induced a reduction in urinary corticosterone levels, perhaps as a result of chronic stress.
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Affiliation(s)
- Daniel Selechnik
- School of Life and Environmental Sciences (SOLES), University of Sydney, Sydney, NSW, Australia
| | - Andrea J West
- Centre for Integrative Ecology, School of Life & Environmental Sciences (LES), Deakin University, Geelong, VIC, Australia
| | - Gregory P Brown
- School of Life and Environmental Sciences (SOLES), University of Sydney, Sydney, NSW, Australia
| | - Kerry V Fanson
- Centre for Integrative Ecology, School of Life & Environmental Sciences (LES), Deakin University, Geelong, VIC, Australia
| | - BriAnne Addison
- Centre for Integrative Ecology, School of Life & Environmental Sciences (LES), Deakin University, Geelong, VIC, Australia
| | - Lee A Rollins
- Centre for Integrative Ecology, School of Life & Environmental Sciences (LES), Deakin University, Geelong, VIC, Australia
| | - Richard Shine
- School of Life and Environmental Sciences (SOLES), University of Sydney, Sydney, NSW, Australia
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Mayfield DL, Launikonis BS, Cresswell AG, Lichtwark GA. Additional in-series compliance reduces muscle force summation and alters the time course of force relaxation during fixed-end contractions. ACTA ACUST UNITED AC 2016; 219:3587-3596. [PMID: 27609762 DOI: 10.1242/jeb.143123] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/31/2016] [Indexed: 02/06/2023]
Abstract
There are high mechanical demands placed on skeletal muscles in movements requiring rapid acceleration of the body or its limbs. Tendons are responsible for transmitting muscle forces, but, because of their elasticity, can manipulate the mechanics of the internal contractile apparatus. Shortening of the contractile apparatus against the stretch of tendon affects force generation according to known mechanical properties; however, the extent to which differences in tendon compliance alter force development in response to a burst of electrical impulses is unclear. To establish the influence of series compliance on force summation, we studied electrically evoked doublet contractions in the cane toad peroneus muscle in the presence and absence of a compliant artificial tendon. Additional series compliance reduced tetanic force by two-thirds, a finding predicted based on the force-length property of skeletal muscle. Doublet force and force-time integral expressed relative to the twitch were also reduced by additional series compliance. Active shortening over a larger range of the ascending limb of the force-length curve and at a higher velocity, leading to a progressive reduction in force-generating potential, could be responsible. Muscle-tendon interaction may also explain the accelerated time course of force relaxation in the presence of additional compliance. Our findings suggest that a compliant tendon limits force summation under constant-length conditions. However, high series compliance can be mechanically advantageous when a muscle-tendon unit is actively stretched, permitting muscle fibres to generate force almost isometrically, as shown during stretch-shorten cycles in locomotor activities. Restricting active shortening would likely favour rapid force development.
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Affiliation(s)
- Dean L Mayfield
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | | | - Andrew G Cresswell
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Glen A Lichtwark
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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