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Benítez S, Figueroa Á, Lagos NA, Silva AX, Duarte C, Vargas CA, Lardies MA, Cárdenas L. Differential gene expression analysis in the scallop Argopecten purpuratus exposed to altered pH and temperature conditions in an upwelling-influenced farming area. Comp Biochem Physiol Part D Genomics Proteomics 2023; 45:101046. [PMID: 36495831 DOI: 10.1016/j.cbd.2022.101046] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 11/17/2022] [Accepted: 11/28/2022] [Indexed: 12/05/2022]
Abstract
Increased carbon dioxide in the atmosphere and its absorption across the ocean surface will alter natural variations in pH and temperature levels, occurring in coastal upwelling ecosystems. The scallop Argopecten purpuratus, one of the most economically important species farmed in northern Chile, has been shown to be vulnerable to these environmental drivers. However, the regulatory responses at the gene-level of scallops to these climate stressors remain almost unknown. Consequently, we used an orthogonal experimental design and RNAseq approach to analyze the acute effects of variability in pH and temperature on gene expression in the muscle tissue of A. purpuratus. In respect to control conditions (pH ~ 8.0/ 14 °C), the influence of low pH (~ 7.7) and temperature (14 °C) induced the activation of several genes associated with apoptotic signaling pathways and protein localization to plasma membrane. Elevated temperature (18 °C) and pH (~8.0) conditions increased the expression of transcripts associated with the activation of muscle contraction, regulation, and sarcomere organization effects on muscle tissue. In scallops exposed to low pH and elevated temperature, the genes expressed were differentially associated with the oxidation-reduction process, signal translation, and positive regulation of GTPase activity. These results indicated that the differentially expressed genes under the experimental conditions tested are mainly related to the mitigation of cellular damage and homeostasis control. Our results add knowledge about the function of the adductor muscle in response to stressors in scallops. Furthermore, these results could help in the identification of molecular biomarkers of stress necessary to be integrated into the aquaculture programs for the mitigation of climate change.
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Affiliation(s)
- Samanta Benítez
- Programa de Doctorado en Biología Marina, Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile; Centro de Investigación e Innovación para el Cambio Climático, Facultad de Ciencias, Universidad Santo Tomás, Santiago, Chile
| | - Álvaro Figueroa
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Nelson A Lagos
- Centro de Investigación e Innovación para el Cambio Climático, Facultad de Ciencias, Universidad Santo Tomás, Santiago, Chile; Instituto Milenio de Socio-Ecología Costera (SECOS), Santiago, Chile
| | - Andrea X Silva
- AUSTRAL-omics, Vicerrectoría de Investigación, Desarrollo y Creación Artística, Universidad Austral de Chile, Chile
| | - Cristian Duarte
- Departamento de Ecología y Biodiversidad, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Cristian A Vargas
- Instituto Milenio de Socio-Ecología Costera (SECOS), Santiago, Chile; Laboratorio de Ecosistemas Costeros y Cambio Ambiental Global (ECCALab), Facultad de Ciencias Ambientales & Centro EULA Chile, Universidad de Concepción, Concepción, Chile
| | - Marco A Lardies
- Instituto Milenio de Socio-Ecología Costera (SECOS), Santiago, Chile; Departamento de Ciencias, Facultad de Artes Liberales, Universidad Adolfo Ibañez, Santiago, Chile
| | - Leyla Cárdenas
- Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Valdivia, Chile.
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Gálvez FE, Saldarriaga-Córdoba M, Huovinen P, Silva AX, Gómez I. Revealing the Characteristics of the Antarctic Snow Alga Chlorominima collina gen. et sp. nov. Through Taxonomy, Physiology, and Transcriptomics. Front Plant Sci 2021; 12:662298. [PMID: 34163502 PMCID: PMC8215615 DOI: 10.3389/fpls.2021.662298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/10/2021] [Indexed: 05/13/2023]
Abstract
Snow algae play crucial roles in cold ecosystems, however, many aspects related to their biology, adaptations and especially their diversity are not well known. To improve the identification of snow algae from colored snow, in the present study we used a polyphasic approach to describe a new Antarctic genus, Chlorominima with the species type Chlorominima collina. This new taxon was isolated of colored snow collected from the Collins Glacier (King George Island) in the Maritime Antarctic region. Microscopy revealed biflagellated ellipsoidal cells with a rounded posterior end, a C-shaped parietal chloroplast without a pyrenoid, eyespot, and discrete papillae. Several of these characteristics are typical of the genus Chloromonas, but the new isolate differs from the described species of this genus by the unusual small size of the cells, the presence of several vacuoles, the position of the nucleus and the shape of the chloroplast. Molecular analyzes confirm that the isolated alga does not belong to Chloromonas and therefore forms an independent lineage, which is closely related to other unidentified Antarctic and Arctic strains, forming a polar subclade in the Stephanosphaerinia phylogroup within the Chlamydomonadales. Secondary structure comparisons of the ITS2 rDNA marker support the idea that new strain is a distinct taxon within of Caudivolvoxa. Physiological experiments revealed psychrophilic characteristics, which are typical of true snow algae. This status was confirmed by the partial transcriptome obtained at 2°C, in which various cold-responsive and cryoprotective genes were identified. This study explores the systematics, cold acclimatization strategies and their implications for the Antarctic snow flora.
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Affiliation(s)
- Francisca E. Gálvez
- Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
- Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Valdivia, Chile
- *Correspondence: Francisca E. Gálvez,
| | - Mónica Saldarriaga-Córdoba
- Centro de Investigación en Recursos Naturales y Sustentabilidad (CIRENYS), Universidad Bernardo O’Higgins, Santiago, Chile
| | - Pirjo Huovinen
- Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
- Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Valdivia, Chile
| | - Andrea X. Silva
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
- AUSTRAL-omics, Vicerrectoría de Investigación, Desarrollo y Creación Artística, Universidad Austral de Chile, Valdivia, Chile
| | - Iván Gómez
- Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
- Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Valdivia, Chile
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Manzi C, Vergara-Amado J, Franco LM, Silva AX. The effect of temperature on candidate gene expression in the brain of honey bee Apis mellifera (Hymenoptera: Apidae) workers exposed to neonicotinoid imidacloprid. J Therm Biol 2020; 93:102696. [DOI: 10.1016/j.jtherbio.2020.102696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 07/27/2020] [Accepted: 08/06/2020] [Indexed: 12/12/2022]
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Nespolo RF, Gaitan-Espitia JD, Quintero-Galvis JF, Fernandez FV, Silva AX, Molina C, Storey KB, Bozinovic F. A functional transcriptomic analysis in the relict marsupial Dromiciops gliroides
reveals adaptive regulation of protective functions during hibernation. Mol Ecol 2018; 27:4489-4500. [DOI: 10.1111/mec.14876] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 09/05/2018] [Accepted: 09/07/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Roberto F. Nespolo
- Instituto de Ciencias Ambientales y Evolutivas; Facultad de Ciencias; Universidad Austral de Chile; Valdivia Chile
- Departamento de Ecología; Center of Applied Ecology and Sustainability (CAPES); Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
- Millennium Institute for Integrative Biology (iBio); Santiago Chile
| | - Juan Diego Gaitan-Espitia
- The Swire Institute of Marine Science and School of Biological Sciences; The University of Hong Kong; Hong Kong SAR China
- CSIRO Oceans & Atmosphere; Hobart Tasmania Australia
| | - Julian F. Quintero-Galvis
- Instituto de Ciencias Ambientales y Evolutivas; Facultad de Ciencias; Universidad Austral de Chile; Valdivia Chile
| | - Fernanda V. Fernandez
- Instituto de Fisiología; Facultad de Medicina; Universidad Austral de Chile; Valdivia Chile
| | - Andrea X. Silva
- AUSTRALomics, Vicerrectoría de Investigación, Desarrollo y Creación Artística; Universidad Austral de Chile; Valdivia Chile
| | - Cristian Molina
- AUSTRALomics, Vicerrectoría de Investigación, Desarrollo y Creación Artística; Universidad Austral de Chile; Valdivia Chile
| | - Kenneth B. Storey
- Department of Biology and Institute of Biochemistry; Carleton University; Ottawa Ontario Canada
| | - Francisco Bozinovic
- Departamento de Ecología; Center of Applied Ecology and Sustainability (CAPES); Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
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Lopes JM, Garcêz RWD, Filgueiras RA, Silva AX, Braz D. COMMITTED EFFECTIVE DOSE DUE TO THE INTAKE OF 40K, 226Ra, 228Ra AND 228Th CONTAINED IN FOODS INCLUDED IN THE DIET OF THE RIO DE JANEIRO CITY POPULATION, BRAZIL. Radiat Prot Dosimetry 2018; 181:149-155. [PMID: 29361110 DOI: 10.1093/rpd/ncx310] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 12/29/2017] [Indexed: 06/07/2023]
Abstract
Annual effective dose due to the consumption of 40K, 226Ra, 228Ra and 228Th was estimated from high-resolution gamma spectrometry, food consumption data for the inhabitants of Rio de Janeiro City and dose coefficients published by the ICRP 119. A total of 31 samples of cereals, grains, vegetables, flours, liquid and perishables were analyzed. 40K was measured in all samples, and bean sample presented highest specific concentration 489.36 ± 23.70 Bq kg-1. The highest specific concentration for 226Ra, 228Ra and 228Th was measured in pumpkin (7.82 ± 1.09 Bq kg-1), carrot (30.18 ± 1.99 Bq kg-1) and beet (2.43 ± 0.48 Bq kg-1), respectively. The highest contribution to annual effective dose came from beans (556.3 μSv), potato (12.5 μSv), carrot (10.3 μSv), banana (4.7 μSv) and beet (3.3 μSv). It was observed that updates of daily food consumption values was the main reason for an up to 10-fold difference between the annual effective dose found in the present study and literature data.
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Affiliation(s)
- J M Lopes
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030, Bloco G, Sala 206-CT, Fundão, Rio de Janeiro, RJ, Brazil
| | - R W D Garcêz
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030, Bloco G, Sala 206-CT, Fundão, Rio de Janeiro, RJ, Brazil
| | - R A Filgueiras
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030, Bloco G, Sala 206-CT, Fundão, Rio de Janeiro, RJ, Brazil
| | - A X Silva
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030, Bloco G, Sala 206-CT, Fundão, Rio de Janeiro, RJ, Brazil
- Polytechnic School, Federal University of Rio de Janeiro, Av. Athos da Silveira Ramos, 149-CT, Fundão, Rio de Janeiro, RJ, Brazil
| | - D Braz
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030, Bloco G, Sala 206-CT, Fundão, Rio de Janeiro, RJ, Brazil
- Polytechnic School, Federal University of Rio de Janeiro, Av. Athos da Silveira Ramos, 149-CT, Fundão, Rio de Janeiro, RJ, Brazil
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Lopes JM, Medeiros MPC, Garcêz RWD, Filgueiras RA, Thalhofer JL, Silva Júnior WFR, Silva AX. Comparison of simulated and experimental values of self-absorption correction factors for a fast and credible adjust in efficiency curve of gamma spectroscopy. Appl Radiat Isot 2018; 141:241-245. [PMID: 29759888 DOI: 10.1016/j.apradiso.2018.05.005] [Citation(s) in RCA: 5] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 05/03/2018] [Accepted: 05/04/2018] [Indexed: 11/30/2022]
Abstract
Self-absorption correction factors are fundamental in spectroscopy to correct the efficiency of the samples detection whose density is different from the radioactive standard. Mathematical simulations have been widespread as a tool to facilitate the procedure of correction factors calculation. In this paper, LabSOCS was used to calculate the self-absorption correction factor for some geometries and the values found were compared to those obtained in MCNP and experimental values. The percentage deviations found for the self-absorption correction factor calculated by LabSOCS were below 1.6% when compared to experimental values. Deviations were below 1.9% in the curve extrapolation of the experimental procedure found in literature. Results obtained show that the deviations increase proportionally to the difference between the density values of the radioactive standard and the sample. High percentage deviations were also noticed in simulations whose samples had high densities, complex geometries and low energy gamma-rays.
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Affiliation(s)
- J M Lopes
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030 - CT, Fundão, 21945-970 Rio de Janeiro, RJ, Brazil.
| | - M P C Medeiros
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030 - CT, Fundão, 21945-970 Rio de Janeiro, RJ, Brazil; Engineering Military Institute, Nuclear Engineering Department, Praça General Tibúrcio, 80, Urca, 22290-270 Rio de Janeiro, RJ, Brazil
| | - R W D Garcêz
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030 - CT, Fundão, 21945-970 Rio de Janeiro, RJ, Brazil
| | - R A Filgueiras
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030 - CT, Fundão, 21945-970 Rio de Janeiro, RJ, Brazil
| | - J L Thalhofer
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030 - CT, Fundão, 21945-970 Rio de Janeiro, RJ, Brazil
| | - W F R Silva Júnior
- Engineering Military Institute, Nuclear Engineering Department, Praça General Tibúrcio, 80, Urca, 22290-270 Rio de Janeiro, RJ, Brazil; State University of Rio de Janeiro, Structures and Foundations Department, R. São Francisco Xavier, 524, Maracanã, 20550-900 Rio de Janeiro, RJ, Brazil
| | - A X Silva
- Nuclear Engineering Program, Federal University of Rio de Janeiro, Av. Horácio Macedo, 2030 - CT, Fundão, 21945-970 Rio de Janeiro, RJ, Brazil; Federal University of Rio de Janeiro, Polytechnic College, Av. Athos da Silveira Ramos, 149 - CT, Fundão, 21941-909 Rio de Janeiro, RJ, Brazil
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Zepeda-Paulo F, Ortiz-Martínez S, Silva AX, Lavandero B. Low bacterial community diversity in two introduced aphid pests revealed with 16S rRNA amplicon sequencing. PeerJ 2018; 6:e4725. [PMID: 29761046 PMCID: PMC5944429 DOI: 10.7717/peerj.4725] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [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: 01/11/2018] [Accepted: 04/16/2018] [Indexed: 02/03/2023] Open
Abstract
Bacterial endosymbionts that produce important phenotypic effects on their hosts are common among plant sap-sucking insects. Aphids have become a model system of insect-symbiont interactions. However, endosymbiont research has focused on a few aphid species, making it necessary to make greater efforts to other aphid species through different regions, in order to have a better understanding of the role of endosymbionts in aphids as a group. Aphid endosymbionts have frequently been studied by PCR-based techniques, using species-specific primers, nevertheless this approach may omit other non-target bacteria cohabiting a particular host species. Advances in high-throughput sequencing technologies are complementing our knowledge of microbial communities by allowing us the study of whole microbiome of different organisms. We used a 16S rRNA amplicon sequencing approach to study the microbiome of aphids in order to describe the bacterial community diversity in introduced populations of the cereal aphids, Sitobion avenae and Rhopalosiphum padi in Chile (South America). An absence of secondary endosymbionts and two common secondary endosymbionts of aphids were found in the aphids R. padi and S. avenae, respectively. Of those endosymbionts, Regiella insecticola was the dominant secondary endosymbiont among the aphid samples. In addition, the presence of a previously unidentified bacterial species closely related to a phytopathogenic Pseudomonad species was detected. We discuss these results in relation to the bacterial endosymbiont diversity found in other regions of the native and introduced range of S. avenae and R. padi. A similar endosymbiont diversity has been reported for both aphid species in their native range. However, variation in the secondary endosymbiont infection could be observed among the introduced and native populations of the aphid S. avenae, indicating that aphid-endosymbiont associations can vary across the geographic range of an aphid species. In addition, we discuss the potential role of aphids as vectors and/or alternative hosts of phytopathogenic bacteria.
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Affiliation(s)
- Francisca Zepeda-Paulo
- Laboratorio de Control Biológico/Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
| | - Sebastían Ortiz-Martínez
- Laboratorio de Control Biológico/Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
| | - Andrea X Silva
- AUSTRAL-omics Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Blas Lavandero
- Laboratorio de Control Biológico/Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
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Vergara-Amado J, Silva AX, Manzi C, Nespolo RF, Cárdenas L. Differential expression of stress candidate genes for thermal tolerance in the sea urchin Loxechinus albus. J Therm Biol 2017; 68:104-109. [DOI: 10.1016/j.jtherbio.2017.03.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 03/15/2017] [Accepted: 03/19/2017] [Indexed: 12/14/2022]
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Guillemin ML, Valero M, Morales Collio K, Pinochet Sanchez R, Henríquez Espinosa M, Silva AX. Microsatellite markers and cytoplasmic sequences reveal contrasting pattern of spatial genetic structure in the red algae species complex Mazzaella laminarioides. J Phycol 2016; 52:806-816. [PMID: 27317474 DOI: 10.1111/jpy.12440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 11/23/2015] [Accepted: 05/04/2016] [Indexed: 06/06/2023]
Abstract
Mazzaella laminarioides is a common haploid-diploid red alga that forms dense beds. This alga has a wide distributional range, covering 3,500 km of the Chilean coast, but is restricted to high rocky intertidal zones. Recently, the existence of three highly divergent genetic lineages was demonstrated for this taxon, and two cytoplasmic markers were used to determine that these lineages are distributed in strict parapatry. Here, using 454 next-generation sequencing, we developed polymorphic microsatellite loci that cross amplify in all three cytoplasmic lineages. Six sites (i.e., two sites within each lineage) were analyzed using nine microsatellite loci. Our work shows that, although substantial cytoplasmic differentiation occurs within M. laminarioides, the microsatellite loci did not retrieve three nuclear genetic clusters as expected. Indeed, while the northernmost and southernmost cytoplasmic lineages form two strongly divergent nuclear groups characterized by diagnostic alleles, the third cytoplasmic lineage did not form a third nuclear independent group. It is possible that inter-lineage gene exchange has occurred, particularly at sites along the contact zone between the different cytoplasmic lineages. This nuclear-cytoplasmic incongruence in M. laminarioides could be explained by incomplete lineage sorting of the nuclear genes or asymmetric introgressive hybridization between the lineages. Finally, highly significant heterozygote deficiencies (suggesting occurrence of intergametophytic selfing) were observed in the three small northernmost sites while the large southernmost sites generally approached panmixia.
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Affiliation(s)
- Marie-Laure Guillemin
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
- CNRS, Sorbonne Universités, UPMC University Paris VI, UMI 3614, Evolutionary Biology and Ecology of Algae, Station Biologique de Roscoff, CS 90074, Place G. Tessier, 296888, Roscoff, France
| | - Myriam Valero
- CNRS, Sorbonne Universités, UPMC University Paris VI, UMI 3614, Evolutionary Biology and Ecology of Algae, Station Biologique de Roscoff, CS 90074, Place G. Tessier, 296888, Roscoff, France
| | - Kennia Morales Collio
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
| | - Ramona Pinochet Sanchez
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
| | - Miguel Henríquez Espinosa
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
| | - Andrea X Silva
- AUSTRAL-omics, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
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Nespolo RF, Silva AX, Figueroa CC, Bacigalupe LD. Anticipatory gene regulation driven by maternal effects in an insect-host system. Ecol Evol 2015; 5:5601-8. [PMID: 27069609 PMCID: PMC4813104 DOI: 10.1002/ece3.1763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [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: 08/06/2015] [Accepted: 08/12/2015] [Indexed: 11/06/2022] Open
Abstract
Adaptive mechanisms involved in the prediction of future environments are common in organisms experiencing temporally variable environments. One of these is AGR (anticipatory gene regulation); in which differential gene expression occur in an individual, triggered by the experience of an ancestor. In this study, we explored the existence of AGR driven by a maternal effect, in an insect–host system. We analyzed gene expression of detoxifying systems in aphids across two generations, by shifting mothers and offspring from chemically defended to nondefended hosts, and vice versa. Then, we measured fitness (intrinsic rate of increase) and the relative abundance of transcripts from certain candidate genes in daughters, using RT‐qPCR (quantitative reverse‐transcription PCR). We found AGR in most cases, but responses varied according to the system being analyzed. For some pathways (e.g., cathepsins), the experience of both mothers and offsprings affected the response (i.e., when both, mother and daughter grew in the defended host, the maximum response was elicited; when only the mother grew in the defended host, an intermediate response was elicited; and when both, mother and daughter grew in a nondefended host, the response was undetectable). In other cases (esterases and GSTs), gene over‐expression was maintained even if the daughter was transferred to the nondefended host. In spite of these changes at the gene‐regulatory level, fitness was constant across hosts, suggesting that insects keep adapted thanks to this fluctuating gene expression. Also, it seems that that telescopic reproduction permits aphids to anticipate stressful environments, by minute changes in the timing of differential gene expression.
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Affiliation(s)
- Roberto F Nespolo
- Instituto de Ciencias Ambientales y Evolutivas Facultad de Ciencias Universidad Austral de Chile Valdivia Chile; Center of Applied Ecology and Sustainability (CAPES) Facultad de Ciencias Biológicas Universidad Católica de Chile Santiago 6513677 Chile
| | - Andrea X Silva
- AUSTRAL-omics Facultad de Ciencias Universidad Austral de Chile Valdivia Chile
| | - Christian C Figueroa
- Laboratorio de Interacciones Insecto-Planta Instituto de Ciencias Biológicas Universidad de Talca 2 Norte 685 Talca Chile; Millennium Nucleus Centre in Molecular Ecology and Evolutionary Applications in the Agroecosystems Universidad de Talca 2 Norte 685 Talca Chile
| | - Leonardo D Bacigalupe
- Instituto de Ciencias Ambientales y Evolutivas Facultad de Ciencias Universidad Austral de Chile Valdivia Chile
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Tapia DH, Silva AX, Ballesteros GI, Figueroa CC, Niemeyer HM, Ramírez CC. Differences in learning and memory of host plant features between specialist and generalist phytophagous insects. Anim Behav 2015. [DOI: 10.1016/j.anbehav.2015.04.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Bacigalupe LD, Barrientos K, Beckerman AP, Carter MJ, Figueroa CC, Foster SP, Moore AJ, Silva AX, Nespolo RF. Can invasions occur without change? A comparison of G-matrices and selection in the peach-potato aphid, Myzus persicae. Ecol Evol 2013; 3:5109-18. [PMID: 24455140 PMCID: PMC3892372 DOI: 10.1002/ece3.883] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [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: 08/06/2013] [Revised: 08/12/2013] [Accepted: 08/30/2013] [Indexed: 11/05/2022] Open
Abstract
Most evolutionary research on biological invasions has focused on changes seen between the native and invaded range for a particular species. However, it is likely that species that live in human-modified habitats in their native range might have evolved specific adaptations to those environments, which increase the likelihood of establishment and spread in similar human-altered environments. From a quantitative genetic perspective, this hypothesis suggests that both native and introduced populations should reside at or near the same adaptive peak. Therefore, we should observe no overall changes in the G (genetic variance-covariance) matrices between native and introduced ranges, and stabilizing selection on fitness-related traits in all populations. We tested these predictions comparing three populations of the worldwide pest Myzus persicae from the Middle East (native range) and the UK and Chile (separately introduced ranges). In general, our results provide mixed support for this idea, but further comparisons of other species are needed. In particular, we found that there has been some limited evolution in the studied traits, with the Middle East population differing from the UK and Chilean populations. This was reflected in the structure of the G-matrices, in which Chile differed from both UK and Middle East populations. Furthermore, the amount of genetic variation was massively reduced in Chile in comparison with UK and Middle East populations. Finally, we found no detectable selection on any trait in the three populations, but clones from the introduced ranges started to reproduce later, were smaller, had smaller offspring, and had lower reproductive fitness than clones from the native range.
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Affiliation(s)
- Leonardo D Bacigalupe
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile P.O. 51110566, Valdivia, Chile
| | - Karin Barrientos
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile P.O. 51110566, Valdivia, Chile
| | - Andrew P Beckerman
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile P.O. 51110566, Valdivia, Chile ; Department of Animal and Plant Sciences, University of Sheffield Sheffield, S102TN, U.K
| | - Mauricio J Carter
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter Cornwall Campus, Penryn, U.K
| | - Christian C Figueroa
- Instituto de Biología Vegetal y Biotecnología, Universidad de Talca 2 Norte 685, Talca, Chile
| | - Stephen P Foster
- Rothamsted Research West Common, Harpenden, Hertfordshire, AL5 2JQ, U.K
| | - Allen J Moore
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter Cornwall Campus, Penryn, U.K ; Department of Genetics, University of Georgia Athens, GA, 30602
| | - Andrea X Silva
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile P.O. 51110566, Valdivia, Chile
| | - Roberto F Nespolo
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile P.O. 51110566, Valdivia, Chile
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Fuentes-Contreras E, Figueroa CC, Silva AX, Bacigalupe LD, Briones LM, Foster SP, Unruh TR. Survey of resistance to four insecticides and their associated mechanisms in different genotypes of the green peach aphid (Hemiptera: Aphididae) from Chile. J Econ Entomol 2013; 106:400-407. [PMID: 23448057 DOI: 10.1603/ec12176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) is amajor pest of agriculture worldwide that has proved to be particularly adept at evolving insecticide resistance. Several mechanisms that confer resistance to many insecticide types have been described in M. persicae. We measured the resistance status of nine multilocus genotypes (MLGs) of this aphid species collected in Chile. MLGs were identified using microsatellite markers, and these MLG clonal populations were measured for the presence of modified acetylcholinesterase (MACE), kdr and super kdr mutations, and enhanced carboxyl esterase activity. Toxicological bioassays were used to estimate aphid LC50 when treated with metamidophos (organophosphate), pirimicarb (dimethyl carbamate), cyfluthrin (pyrethroid), and imidacloprid (neonicotinoid). Two MLGs presented >20-fold resistance to pirimicarb, which was associated with the MACE mutation in the heterozygous condition. The kdr mutation was found in only four MLGs in the heterozygous condition and they showed resistance ratios (RR) to cyfluthrin of less than sevenfold. The super kdr mutation was not detected. Enhanced carboxyl esterase activity was predominantly found in the susceptible (S) to first level of resistance (R1) with RR to metamidophos less than eight-fold. Finally, RR to imidacloprid was also less than eight-fold in all MLGs tested. A few MLGs with resistance to pirimicarb were found, while susceptibility to cyfluthrin, metamidophos and imidacloprid was still predominant. A significant positive correlation between imidacloprid tolerance with pirimicarb resistance was detected, as well as between imidacloprid and metamidophos tolerance. With the increase in the use of neonicotinoid insecticides, better rotation of insecticides with different modes of action will be necessary to prevent further development of M. persicae insecticide resistance in Chile.
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Affiliation(s)
- Eduardo Fuentes-Contreras
- Departamento de Producción Agrícola, Facultad de Ciencias Agrarias, Universidad de Talca, Casilla 747, Talca, Chile.
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14
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Cordeiro TPV, Silva AX. Calculation of conversion coefficients for air kerma to ambient dose equivalent using transmitted spectra of megavoltage X-rays through concrete. Radiat Prot Dosimetry 2012; 152:455-462. [PMID: 22683619 DOI: 10.1093/rpd/ncs070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
With the fast advancement of technology, (60)Co teletherapy units are largely being replaced with medical linear accelerators. In most cases, the linear accelerator tends to be installed in the same room in which the (60)Co teletherapy unit was previously placed. If in-depth structural remodelling is out of the question, high-density concrete is usually used to improve shielding against primary, scatter and leakage radiation originating in the new equipment. This work presents a study based on Monte Carlo simulations of the transmission of some clinical photon spectra (from 6, 10, 15, 18 and 25 MV accelerators) through concrete, considering two different densities. Concrete walls with thickness ranging from 0.70 to 2.0 m were irradiated with 30 cm×30 cm primary beam spectra. The results show that the thickness of the barrier decreases up to ∼65 % when barite (high-density concrete) is used instead of ordinary concrete. The average energies of primary and transmitted beam spectra were also calculated. In addition, conversion coefficients from air kerma to ambient dose equivalent, H*(d)/K(air), and air kerma to effective dose, E/K(air), for photon spectra from the transmitted spectra were calculated and compared. The results suggest that the 10-mm depth is not the best choice to represent the effective dose.
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Affiliation(s)
- T P V Cordeiro
- PEN/COPPE/CT/UFRJ, Universidade Federal do Rio de Janeiro, 21945-970-Ilha do Fundão, Caixa Postal, 68509 Rio de Janeiro, RJ, Brazil.
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15
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Silva AX, Jander G, Samaniego H, Ramsey JS, Figueroa CC. Insecticide resistance mechanisms in the green peach aphid Myzus persicae (Hemiptera: Aphididae) I: A transcriptomic survey. PLoS One 2012; 7:e36366. [PMID: 22685538 PMCID: PMC3369866 DOI: 10.1371/journal.pone.0036366] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 04/05/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Insecticide resistance is one of the best examples of rapid micro-evolution found in nature. Since the development of the first synthetic insecticide in 1939, humans have invested considerable effort to stay ahead of resistance phenotypes that repeatedly develop in insects. Aphids are a group of insects that have become global pests in agriculture and frequently exhibit insecticide resistance. The green peach aphid, Myzus persicae, has developed resistance to at least seventy different synthetic compounds, and different insecticide resistance mechanisms have been reported worldwide. METHODOLOGY/PRINCIPAL FINDINGS To further characterize this resistance, we analyzed genome-wide transcriptional responses in three genotypes of M. persicae, each exhibiting different resistance mechanisms, in response to an anti-cholinesterase insecticide. The sensitive genotype (exhibiting no resistance mechanism) responded to the insecticide by up-regulating 183 genes primarily ones related to energy metabolism, detoxifying enzymes, proteins of extracellular transport, peptidases and cuticular proteins. The second genotype (resistant through a kdr sodium channel mutation), up-regulated 17 genes coding for detoxifying enzymes, peptidase and cuticular proteins. Finally, a multiply resistant genotype (carrying kdr and a modified acetylcholinesterase), up-regulated only 7 genes, appears not to require induced insecticide detoxification, and instead down-regulated many genes. CONCLUSIONS/SIGNIFICANCE This study suggests strongly that insecticide resistance in M. persicae is more complex that has been described, with the participation of a broad array of resistance mechanisms. The sensitive genotype exhibited the highest transcriptional plasticity, accounting for the wide range of potential adaptations to insecticides that this species can evolve. In contrast, the multiply resistant genotype exhibited a low transcriptional plasticity, even for the expression of genes encoding enzymes involved in insecticide detoxification. Our results emphasize the value of microarray studies to search for regulated genes in insects, but also highlights the many ways those different genotypes can assemble resistant phenotypes depending on the environmental pressure.
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Affiliation(s)
- Andrea X. Silva
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Georg Jander
- Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America
| | - Horacio Samaniego
- Instituto de Silvicultura, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, Valdivia, Chile
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - John S Ramsey
- Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America
| | - Christian C. Figueroa
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
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16
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Silva AX, Bacigalupe LD, Luna-Rudloff M, Figueroa CC. Insecticide resistance mechanisms in the green peach aphid Myzus persicae (Hemiptera: Aphididae) II: Costs and benefits. PLoS One 2012; 7:e36810. [PMID: 22685539 PMCID: PMC3369902 DOI: 10.1371/journal.pone.0036810] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 04/06/2012] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Among herbivorous insects that have exploited agro-ecosystems, the peach-potato aphid, Myzus persicae, is recognized as one of the most important agricultural pests worldwide. Uses over 400 plant species and has evolved different insecticides resistance mechanisms. As M. persicae feeds upon a huge diversity of hosts, it has been exposed to a wide variety of plant allelochemicals, which probably have promoted a wide range of detoxification systems. METHODOLOGY/PRINCIPAL FINDINGS In this work we (i) evaluated whether insecticide resistance mutations (IRM) in M. persicae can give an advantage in terms of reproductive fitness when aphids face two hosts, pepper (Capsicum annuum) a suitable host and radish (Raphanus sativus) the unfavorable host and (ii) examined the transcriptional expression of six genes that are known to be up-regulated in response to insecticides. Our results show a significant interaction between host and IRM on the intrinsic rate of increase (r(m)). Susceptible genotypes (not carrying insensitivity mutations) had a higher r(m) on pepper, and the transcriptional levels of five genes increased on radish. The r(m) relationship was reversed on the unfavorable host; genotypes with multiple IRM exhibited higher r(m), without altering the transcriptional levels of the studied genes. Genotypes with one IRM kept a similar r(m) on both hosts, but they increased the transcriptional levels of two genes. CONCLUSIONS/SIGNIFICANCE Although we have studied only nine genotypes, overall our results are in agreement with the general idea that allelochemical detoxification systems could constitute a pre-adaptation for the development of insecticide resistance. Genotypes carrying IRM exhibited a higher r(m) than susceptible genotypes on radish, the more unfavorable host. Susceptible genotypes should be able to tolerate the defended host by up-regulating some metabolic genes that are also responding to insecticides. Hence, our results suggest that the trade-off among resistance mechanisms might be quite complex, with a multiplicity of costs and benefits depending on the environment.
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Affiliation(s)
- Andrea X. Silva
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Leonardo D. Bacigalupe
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Manuela Luna-Rudloff
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Christian C. Figueroa
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
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17
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Boia LS, Menezes AF, Cardoso MAC, da Rosa LAR, Batista DVS, Cardoso SC, Silva AX, Facure A. Application of digital image processing for the generation of voxels phantoms for Monte Carlo simulation. Appl Radiat Isot 2011; 70:144-8. [PMID: 21945017 DOI: 10.1016/j.apradiso.2011.08.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 08/12/2011] [Accepted: 08/15/2011] [Indexed: 11/29/2022]
Abstract
This paper presents the application of a computational methodology for optimizing the conversion of medical tomographic images in voxel anthropomorphic models for simulation of radiation transport using the MCNP code. A computational system was developed for digital image processing that compresses the information from the DICOM medical image before it is converted to the Scan2MCNP software input file for optimization of the image data. In order to validate the computational methodology, a radiosurgery treatment simulation was performed using the Alderson Rando phantom and the acquisition of DICOM images was performed. The simulation results were compared with data obtained with the BrainLab planning system. The comparison showed good agreement for three orthogonal treatment beams of (60)Co gamma radiation. The percentage differences were 3.07%, 0.77% and 6.15% for axial, coronal and sagital projections, respectively.
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Affiliation(s)
- L S Boia
- Programa de Engenharia Nuclear/COPPE, Brazil
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18
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Correa SCA, Souza EM, Oliveira DF, Silva AX, Lopes RT, Marinho C, Camerini CS. Assessment of weld thickness loss in offshore pipelines using computed radiography and computational modeling. Appl Radiat Isot 2009; 67:1824-8. [PMID: 19540128 DOI: 10.1016/j.apradiso.2009.05.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 04/09/2009] [Accepted: 05/24/2009] [Indexed: 11/19/2022]
Abstract
In order to guarantee the structural integrity of oil plants it is crucial to monitor the amount of weld thickness loss in offshore pipelines. However, in spite of its relevance, this parameter is very difficult to determine, due to both the large diameter of most pipes and the complexity of the multi-variable system involved. In this study, a computational modeling based on Monte Carlo MCNPX code is combined with computed radiography to estimate the weld thickness loss in large-diameter offshore pipelines. Results show that computational modeling is a powerful tool to estimate intensity variations in radiographic images generated by weld thickness variations, and it can be combined with computed radiography to assess weld thickness loss in offshore and subsea pipelines.
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Affiliation(s)
- S C A Correa
- Programa de Engenharia Nuclear/COPPE, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Rio de Janeiro, RJ, Brasil.
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19
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Abstract
The knowledge of neutron reflection coefficients is of practical interest when projecting the shielding of radiotherapy rooms, since it is known that about 75% of the neutrons at the maze entrance of these rooms are scattered neutrons. In a previous paper, the energy spectra of photoneutrons were calculated, when reflected by ordinary, high-density concrete and wood barriers, using the MCNP5 code, considering normal incidence and neutron incident energies varying between 0.1 and 10 MeV. It was found that the mean energy of the reflected neutrons does not depend on the reflection angle and that these mean energies are lower in wood and barytes concrete, compared with ordinary concrete. In the present work, the simulation of neutron reflection coefficients were completed, considering the case when these particles do not collide frontally with the barriers, which constitute the radiotherapy room walls. Some simulations were also made to evaluate how neutron equivalent doses at the position of the room door is affected when the maze walls are lined with neutron absorbing materials, such as wood itself or borated polyethylene. Finally, capture gamma rays dose at the entrance of rooms with different maze lengths were also simulated. The results were discussed in the light of the albedo concepts presented in the literature and some of these results were confronted with others, finding good agreement between them.
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Affiliation(s)
- A Facure
- Comissão Nacional de Energia Nuclear, R. Gal. Severiano 90, sala 405, 22294-900 Rio de Janeiro, RJ, Brazil
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20
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Rebello WF, Silva AX, Facure A. Multileaf shielding design against neutrons produced by medical linear accelerators. Radiat Prot Dosimetry 2008; 128:227-33. [PMID: 17569690 DOI: 10.1093/rpd/ncm312] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
This work aims at presenting a study using Monte Carlo simulation of a Multileaf Shielding (MLS) System designed to be used for the protection of patients who undergo radiotherapy treatment, against undesired exposure to neutrons produced in the components of the medical linear accelerator heads. The choice of radiotherapy equipment as the subject of study fell on the Varian Clinac 2,100/2,300 with MLC-120 operating at 18 MeV. The general purpose Monte Carlo N-Particle radiation transport code, MCNP5, was used in the computer simulation in order to determine the ambient dose equivalent, H (10), on several points on the patient's plane, with the equipment operation with and without the MLS. The results of the simulations showed a significant neutron dose reduction after the inclusion of the proposed shielding.
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Affiliation(s)
- W F Rebello
- (PEN/COPPE-DNC/POLI)CT/UFRJ, Ilha do Fundão, PO Box 68509, 21945-970, Rio de Janeiro, RJ, Brazil.
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21
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Souza EM, Correa SCA, Silva AX, Lopes RT, Oliveira DF. Methodology for digital radiography simulation using the Monte Carlo code MCNPX for industrial applications. Appl Radiat Isot 2007; 66:587-92. [PMID: 18339548 DOI: 10.1016/j.apradiso.2007.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Revised: 10/22/2007] [Accepted: 11/12/2007] [Indexed: 10/22/2022]
Abstract
This work presents a methodology for digital radiography simulation for industrial applications using the MCNPX radiography tally. In order to perform the simulation, the energy-dependent response of a BaFBr imaging plate detector was modeled and introduced in the MCNPX radiography tally input. In addition, a post-processing program was used to convert the MCNPX radiography tally output into 16-bit digital images. Simulated and experimental images of a steel pipe containing corrosion alveoli and stress corrosion cracking were compared, and the results showed good agreement between both images.
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Affiliation(s)
- E M Souza
- Programa de Engenharia Nuclear/COPPE, Universidade Federal do Rio de Janeiro, Centro de Tecnologia Ilha do Fundão, Caixa Postal 68509, 21945-970 Rio de Janeiro, RJ, Brazil.
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22
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Facure A, Silva AX. The use of high-density concretes in radiotherapy treatment room design. Appl Radiat Isot 2007; 65:1023-8. [PMID: 17531498 DOI: 10.1016/j.apradiso.2007.04.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 04/03/2007] [Accepted: 04/06/2007] [Indexed: 11/26/2022]
Abstract
With the modernization of radiotherapic centers, medical linear accelerators are largely replacing (60)Co teletherapy units. In many cases, the same vault housing the (60)Co teletherapy unit is reused for the linear accelerator and, when space is at a premium, high-density concrete (3.0-5.0 g/cm(3)) is employed to provide shielding against the primary, scatter and leakage radiation. This work presents a study based on Monte Carlo simulations of transmission of some clinical photon spectra (of 4-10 MV accelerators) through some types of high-density concretes, normally used in the construction of radiotherapy bunkers. From the simulations, the initial and subsequent tenth-value layers (TVL) for these materials, taking into account realistic clinical photon spectra, are presented, for primary radiation.
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Affiliation(s)
- A Facure
- Comissão Nacional de Energia Nuclear, R. Gal. Severiano 90, Sala 405, 22294-900 Rio de Janeiro, RJ, Brazil.
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23
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Abstract
Currently, teletherapy machines of cobalt and caesium are being replaced by linear accelerators. The maximum photon energy in these machines can vary from 4 to 25 MeV, and one of the great advantages of these equipments is that they do not have a radioactive source incorporated. High-energy (E > 10 MV) medical linear accelerators offer several physical advantages over lower energy ones: the skin dose is lower, the beam is more penetrating, and the scattered dose to tissues outside the target volume is smaller. Nevertheless, the contamination of undesirable neutrons in the therapeutic beam, generated by the high-energy photons, has become an additional problem as long as patient protection and occupational doses are concerned. The treatment room walls are shielded to attenuate the primary and secondary X-ray fluence, and this shielding is generally adequate to attenuate the neutrons. However, these neutrons are scattered through the treatment room maze and may result in a radiological problem at the door entrance, a high occupancy area in a radiotherapy facility. In this article, we used MCNP Monte Carlo simulation to calculate neutron doses in the maze of radiotherapy rooms and we suggest an alternative method to the Kersey semi-empirical model of neutron dose calculation at the entrance of mazes. It was found that this new method fits better measured values found in literature, as well as our Monte Carlo simulated ones.
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Affiliation(s)
- R C Falcão
- Comissão Nacional de Energia Nuclear, Rua Gal. Severiano 90, sala 405, 22294-900 Rio de Janeiro, RJ, Brazil.
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24
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Abstract
In this work, the energy spectra of photoneutrons, scattered by ordinary, high-density concrete and wood barriers, have been evaluated using the MCNP4B code. These spectra were calculated for different scattering angles, and for incident neutron energies varying between 0.1 and 10 MeV. The results presented are required to simulate typical photoneutron fluence, produced by medical accelerators, which is scattered by the room walls and reaches the door. It was found that the mean energy of the scattered neutrons does not depend on the scattering angle. Furthermore, it was found that the scattered neutron energies are lower in wood and baryte concrete, which indicates that these materials can be used for lining the maze walls in order to reduce neutron dose at the room door. These data will help to estimate the personal dose received by the patient and staff in radiotherapy facilities.
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Affiliation(s)
- A Facure
- Comissão Nacional de Energia Nuclear, R. Gal. Severiano 90, sala 405, 22294-900, Rio de Janeiro-RJ, Brazil.
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25
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Vitorelli JC, Silva AX, Crispim VR, da Fonseca ES, Pereira WW. Monte Carlo simulation of response function for a NaI(Tl) detector for gamma rays from 241Am/Be source. Appl Radiat Isot 2005; 62:619-22. [PMID: 15701418 DOI: 10.1016/j.apradiso.2004.07.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2004] [Revised: 07/07/2004] [Accepted: 07/14/2004] [Indexed: 11/23/2022]
Abstract
The general purpose computer code MCNP4B was used to simulate the response function of a bare NaI(Tl) detector crystal for gamma rays from an 241Am/Be source capsule. The simulated spectral shape generated by the MCNP4B code was compared with the measured spectral shape obtained using a gamma-ray spectrometer with a cylindrical shape, 7.62 cm x 7.62 cm, NaI(Tl). In general, the agreement between the simulation and the experimental response function was good.
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Affiliation(s)
- J C Vitorelli
- PEN/COPPE/UFRJ, CEP 21945-970-Caixa Postal 68509 Rio de Janeiro, RJ, Brazil
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26
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Facure A, Falcão RC, Silva AX, Crispim VR, Vitorelli JC. A study of neutron spectra from medical linear accelerators. Appl Radiat Isot 2005; 62:69-72. [PMID: 15498687 DOI: 10.1016/j.apradiso.2004.05.072] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2004] [Revised: 04/05/2004] [Accepted: 05/10/2004] [Indexed: 11/18/2022]
Abstract
Medical accelerators with photon energies over 10 MeV generate an undesired fast neutron contamination in the therapeutic beam. In this work, the Monte Carlo code MCNP was used to simulate the transport of these photoneutrons across the head of various medical accelerators of high energy. The average and most probable neutron energies were obtained from these spectra, before and after crossing the accelerator shielding. The degradation of these spectra, when they cross concrete barriers with thickness which vary between 25 and 100 cm, was also studied.
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Affiliation(s)
- A Facure
- Comissão Nacional de Energia Nuclear, R. Gal. Severiano 90, sala 405, 22294-900, Rio de Janeiro, RJ, Brazil
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27
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Lima MAF, Silva AX, Crispim VR. Calculation of conversion coefficients for clinical photon spectra using the MCNP code. Radiat Prot Dosimetry 2004; 111:9-12. [PMID: 15367760 DOI: 10.1093/rpd/nch351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In this work, the MCNP4B code has been employed to calculate conversion coefficients from air kerma to the ambient dose equivalent, H*(10)/Ka, for monoenergetic photon energies from 10 keV to 50 MeV, assuming the kerma approximation. Also estimated are the H*(10)/Ka for photon beams produced by linear accelerators, such as Clinac-4 and Clinac-2500, after transmission through primary barriers of radiotherapy treatment rooms. The results for the conversion coefficients for monoenergetic photon energies, with statistical uncertainty <2%, are compared with those in ICRP publication 74 and good agreements were obtained. The conversion coefficients calculated for real clinic spectra transmitted through walls of concrete of 1, 1.5 and 2 m thick, are in the range of 1.06-1.12 Sv Gy(-1).
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Affiliation(s)
- M A F Lima
- PEN/COPPE/CT/UFRJ, Universidade Federal do Rio de Janeiro, 21945-970-Ilha do Fundão, Caixa Postal 68509, Rio de Janeiro, RJ, Brazil
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