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Lopes AR, Moraes JS, Martins CDMG. Effects of the herbicide glyphosate on fish from embryos to adults: a review addressing behavior patterns and mechanisms behind them. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2022; 251:106281. [PMID: 36103761 DOI: 10.1016/j.aquatox.2022.106281] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 07/29/2022] [Accepted: 08/24/2022] [Indexed: 06/15/2023]
Abstract
The use of agrochemicals has grown in recent years following the increase in agricultural productivity, to eliminate weeds that can compromise crop yields. The intensive use of these products combined with the lack of treatment of agricultural wastewater is causing contamination of the natural environments, especially the aquatics. Glyphosate [N-(phosphonomethyl) glycine] is the most commonly used herbicide in agriculture worldwide. Studies have shown that this compound is toxic to a variety of fish species at the concentrations of environmental relevance. Glyphosate-based herbicides can affect fish biochemical, physiological, endocrine, and behavioral pathways. Changes in behaviors such as foraging, escaping from predators, and courtship can compromise the survival of species and even communities. The behavior patterns of fish has been shown to be a sensitive tool for risk assessment. In this sense, this review summarizes and discusses the toxic effects of glyphosate and its formulations on the behavior of fish in different life stages. Additionally, behavioral impairments were associated with other negative effects of glyphosate such as energy imbalance, stress responses, AChE inhibition, and physiological and endocrine disturbances, which are evidenced and described in the literature. Graphical abstract.
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Affiliation(s)
- Andressa Rubim Lopes
- Programa de Pós-Graduação em Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Rio Grande RS, Brazil.
| | - Jenifer Silveira Moraes
- Programa de Pós-Graduação em Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Rio Grande RS, Brazil
| | - Camila de Martinez Gaspar Martins
- Programa de Pós-Graduação em Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Rio Grande RS, Brazil
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2
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Álvarez-Quintero N, Velando A, Kim SY. Long-Lasting Negative Effects of Learning Tasks During Early Life in the Three-Spined Stickleback. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.562404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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Pereira PDC, Henrique EP, Porfírio DM, Crispim CCDS, Campos MTB, de Oliveira RM, Silva IMS, Guerreiro LCF, da Silva TWP, da Silva ADJF, Rosa JBDS, de Azevedo DLF, Lima CGC, Castro de Abreu C, Filho CS, Diniz DLWP, Magalhães NGDM, Guerreiro-Diniz C, Diniz CWP, Diniz DG. Environmental Enrichment Improved Learning and Memory, Increased Telencephalic Cell Proliferation, and Induced Differential Gene Expression in Colossoma macropomum. Front Pharmacol 2020; 11:840. [PMID: 32595498 PMCID: PMC7303308 DOI: 10.3389/fphar.2020.00840] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 05/21/2020] [Indexed: 01/06/2023] Open
Abstract
Fish use spatial cognition based on allocentric cues to navigate, but little is known about how environmental enrichment (EE) affects learning and memory in correlation with hematological changes or gene expression in the fish brain. Here we investigated these questions in Colossoma macropomum (Teleostei). Fish were housed for 192 days in either EE or in an impoverished environment (IE) aquarium. EE contained toys, natural plants, and a 12-h/day water stream for voluntary exercise, whereas IE had no toys, plants, or water stream. A third plus maze aquarium was used for spatial and object recognition tests. Compared with IE, the EE fish showed greater learning rates, body length, and body weight. After behavioral tests, whole brain tissue was taken, stored in RNA-later, and then homogenized for DNA sequencing after conversion of isolated RNA. To compare read mapping and gene expression profiles across libraries for neurotranscriptome differential expression, we mapped back RNA-seq reads to the C. macropomum de novo assembled transcriptome. The results showed significant differential behavior, cell counts and gene expression in EE and IE individuals. As compared with IE, we found a greater number of cells in the telencephalon of individuals maintained in EE but no significant difference in the tectum opticum, suggesting differential plasticity in these areas. A total of 107,669 transcripts were found that ultimately yielded 64 differentially expressed transcripts between IE and EE brains. Another group of adult fish growing in aquaculture conditions were either subjected to exercise using running water flow or maintained sedentary. Flow cytometry analysis of peripheral blood showed a significantly higher density of lymphocytes, and platelets but no significant differences in erythrocytes and granulocytes. Thus, under the influence of contrasting environments, our findings showed differential changes at the behavioral, cellular, and molecular levels. We propose that the differential expression of selected transcripts, number of telencephalic cell counts, learning and memory performance, and selective hematological cell changes may be part of Teleostei adaptive physiological responses triggered by EE visuospatial and somatomotor stimulation. Our findings suggest abundant differential gene expression changes depending on environment and provide a basis for exploring gene regulation mechanisms under EE in C. macropomum.
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Affiliation(s)
- Patrick Douglas Corrêa Pereira
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança, Brazil
| | - Ediely Pereira Henrique
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança, Brazil
| | - Danillo Monteiro Porfírio
- Laboratório de Investigação em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | | | - Maitê Thaís Barros Campos
- Laboratório de Investigação em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | - Renata Melo de Oliveira
- Laboratório de Investigação em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | - Isabella Mesquita Sfair Silva
- Laboratório de Investigação em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | - Luma Cristina Ferreira Guerreiro
- Laboratório de Investigação em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | - Tiago Werley Pires da Silva
- Laboratório de Investigação em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | | | - João Batista da Silva Rosa
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança, Brazil
| | | | - Cecília Gabriella Coutinho Lima
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança, Brazil
| | - Cintya Castro de Abreu
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança, Brazil
| | - Carlos Santos Filho
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança, Brazil
| | | | - Nara Gyzely de Morais Magalhães
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança, Brazil
| | - Cristovam Guerreiro-Diniz
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança, Brazil
| | - Cristovam Wanderley Picanço Diniz
- Laboratório de Investigação em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | - Daniel Guerreiro Diniz
- Laboratório de Investigação em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
- Laboratório de Microscopia Eletrônica, Instituto Evandro Chagas, Belém, Brazil
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Hall ZJ, Tropepe V. Using Teleost Fish to Discern Developmental Signatures of Evolutionary Adaptation From Phenotypic Plasticity in Brain Structure. Front Neuroanat 2020; 14:10. [PMID: 32256320 PMCID: PMC7093710 DOI: 10.3389/fnana.2020.00010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/02/2020] [Indexed: 01/23/2023] Open
Abstract
Traditionally, the impact of evolution on the central nervous system has been studied by comparing the sizes of brain regions between species. However, more recent work has demonstrated that environmental factors, such as sensory experience, modulate brain region sizes intraspecifically, clouding the distinction between evolutionary and environmental sources of neuroanatomical variation in a sampled brain. Here, we review how teleost fish have played a central role in shaping this traditional understanding of brain structure evolution between species as well as the capacity for the environment to shape brain structure similarly within a species. By demonstrating that variation measured by brain region size varies similarly both inter- and intraspecifically, work on teleosts highlights the depth of the problem of studying brain evolution using neuroanatomy alone: even neurogenesis, the primary mechanism through which brain regions are thought to change size between species, also mediates experience-dependent changes within species. Here, we argue that teleost models also offer a solution to this overreliance on neuroanatomy in the study of brain evolution. With the advent of work on teleosts demonstrating interspecific evolutionary signatures in embryonic gene expression and the growing understanding of developmental neurogenesis as a multi-stepped process that may be differentially regulated between species, we argue that the tools are now in place to reframe how we compare brains between species. Future research can now transcend neuroanatomy to leverage the experimental utility of teleost fishes in order to gain deeper neurobiological insight to help us discern developmental signatures of evolutionary adaptation from phenotypic plasticity.
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Affiliation(s)
- Zachary J Hall
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Vincent Tropepe
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
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Effects of different levels of environmental enrichment on the sheltering behaviors, brain development and cortisol levels of black rockfish Sebastes schlegelii. Appl Anim Behav Sci 2019. [DOI: 10.1016/j.applanim.2019.06.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Berbel-Filho WM, Rodríguez-Barreto D, Berry N, Garcia De Leaniz C, Consuegra S. Contrasting DNA methylation responses of inbred fish lines to different rearing environments. Epigenetics 2019; 14:939-948. [PMID: 31144573 DOI: 10.1080/15592294.2019.1625674] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Epigenetic mechanisms generate plastic phenotypes that can become locally adapted across environments. Disentangling genomic from epigenomic variation is challenging in sexual species due to genetic variation among individuals, but it is easier in self-fertilizing species. We analysed DNA methylation patterns of two highly inbred strains of a naturally self-fertilizing fish reared in two contrasting environments to investigate the obligatory (genotype-dependent), facilitated (partially depend on the genotype) or pure (genotype-independent) nature of the epigenetic variation. We found higher methylation differentiation between genotypes than between environments. Most methylation differences between environments common to both strains followed a pattern where the two genotypes (inbred lines) responded to the same environmental context with contrasting DNA methylation levels (facilitated epialleles). Our findings suggest that, at least in part, DNA methylation could depend on the dynamic interaction between the genotype and the environment, which could explain the plasticity of epigenetically mediated phenotypes.
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Affiliation(s)
| | | | - Nikita Berry
- a Department of Biosciences, Swansea University , Swansea , UK
| | | | - Sofia Consuegra
- a Department of Biosciences, Swansea University , Swansea , UK
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8
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Fong S, Buechel SD, Boussard A, Kotrschal A, Kolm N. Plastic changes in brain morphology in relation to learning and environmental enrichment in the guppy ( Poecilia reticulata). ACTA ACUST UNITED AC 2019; 222:jeb.200402. [PMID: 31053644 DOI: 10.1242/jeb.200402] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 04/26/2019] [Indexed: 12/19/2022]
Abstract
Despite the common assumption that the brain is malleable to surrounding conditions mainly during ontogeny, plastic neural changes can occur also in adulthood. One of the driving forces responsible for alterations in brain morphology is increasing environmental complexity that may demand enhanced cognitive abilities (e.g. attention, memory and learning). However, studies looking at the relationship between brain morphology and learning are scarce. Here, we tested the effects of both learning and environmental enrichment on neural plasticity in guppies (Poecilia reticulata), by means of either a reversal-learning test or a spatial-learning test. Given considerable evidence supporting environmentally induced plastic alterations, two separate control groups that were not subjected to any cognitive test were included to account for potential changes induced by the experimental setup alone. We did not find any effect of learning on any of our brain measurements. However, we found strong evidence for an environmental effect, where fish given access to the spatial-learning environment had larger relative brain size and optic tectum size in relation to those exposed to the reversal-learning environment. Our results demonstrate the plasticity of the adult brain to respond adaptively mainly to environmental conditions, providing support for the environmental enhancement theory.
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Affiliation(s)
- Stephanie Fong
- Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Séverine D Buechel
- Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Annika Boussard
- Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden
| | | | - Niclas Kolm
- Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden
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Abreu CC, Fernandes TN, Henrique EP, Pereira PDC, Marques SB, Herdeiro SLS, Oliveira FRR, Magalhães NGM, Anthony DC, Melo MAD, Guerreiro-Diniz C, Diniz DG, Picanço-Diniz CW. Small-scale environmental enrichment and exercise enhance learning and spatial memory of Carassius auratus, and increase cell proliferation in the telencephalon: an exploratory study. ACTA ACUST UNITED AC 2019; 52:e8026. [PMID: 31038577 PMCID: PMC6487742 DOI: 10.1590/1414-431x20198026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 02/25/2019] [Indexed: 12/25/2022]
Abstract
Carassius auratus is a teleost fish that has been largely used in behavioral studies. However, little is known about potential environmental influences on its performance of learning and memory tasks. Here, we investigated this question in C. auratus, and searched for potential correlation between exercise and visuospatial enrichment with the total number of telencephalic glia and neurons. To that end, males and females were housed for 183 days in either an enriched (EE) or impoverished environment (IE) aquarium. EE contained toys, natural plants, and a 12-hour/day water stream for voluntary exercise, whereas the IE had none of the above. A third plus-maze aquarium was used for spatial and object recognition tests. Different visual clues in 2 of its 4 arms were used to guide fish to reach the criteria to complete the task. The test consisted of 30 sessions and was concluded when each animal performed three consecutive correct choices or seven alternated, each ten trials. Learning rates revealed significant differences between EE and IE fish. The optical fractionator was used to estimate the total number of telencephalic cells that were stained with cresyl violet. On average, the total number of cells in the subjects from EE was higher than those from subjects maintained in IE (P=0.0202). We suggest that environmental enrichment significantly influenced goldfish spatial learning and memory abilities, and this may be associated with an increase in the total number of telencephalic cells.
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Affiliation(s)
- C C Abreu
- Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Laboratório de Neurodegeneração e Infecção, Universidade Federal do Pará, Belém, PA, Brasil
| | - T N Fernandes
- Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Laboratório de Neurodegeneração e Infecção, Universidade Federal do Pará, Belém, PA, Brasil
| | - E P Henrique
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação Ciência e Tecnologia do Pará, Bragança, PA, Brasil
| | - P D C Pereira
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação Ciência e Tecnologia do Pará, Bragança, PA, Brasil
| | - S B Marques
- Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Laboratório de Neurodegeneração e Infecção, Universidade Federal do Pará, Belém, PA, Brasil
| | - S L S Herdeiro
- Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Laboratório de Neurodegeneração e Infecção, Universidade Federal do Pará, Belém, PA, Brasil
| | - F R R Oliveira
- Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Laboratório de Neurodegeneração e Infecção, Universidade Federal do Pará, Belém, PA, Brasil
| | - N G M Magalhães
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação Ciência e Tecnologia do Pará, Bragança, PA, Brasil
| | - D C Anthony
- University of Oxford, Department of Pharmacology, Mansfield Road, Oxford, United Kingdom
| | - M A D Melo
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação Ciência e Tecnologia do Pará, Bragança, PA, Brasil
| | - C Guerreiro-Diniz
- Laboratório de Biologia Molecular e Neuroecologia, Instituto Federal de Educação Ciência e Tecnologia do Pará, Bragança, PA, Brasil
| | - D G Diniz
- Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Laboratório de Neurodegeneração e Infecção, Universidade Federal do Pará, Belém, PA, Brasil
| | - C W Picanço-Diniz
- Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Laboratório de Neurodegeneração e Infecção, Universidade Federal do Pará, Belém, PA, Brasil
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Vas J, Chojnacki RM, Andersen IL. Search Behavior in Goat ( Capra hircus) Kids From Mothers Kept at Different Animal Densities Throughout Pregnancy. Front Vet Sci 2019; 6:21. [PMID: 30854371 PMCID: PMC6396719 DOI: 10.3389/fvets.2019.00021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 01/18/2019] [Indexed: 02/02/2023] Open
Abstract
Individual differences in cognitive performance are often reported but factors related to variation within species are rarely addressed. Goats (Capra hircus) have been subjects of many cognitive studies recently but without focus on individual variation. Among others, factors such as prenatal stress and sex of the individual have been proposed as possible explanations for individual variation in cognitive skills. We aimed to study whether prenatal environment, prenatal stress, litter size, sex, and birth weight influences search behavior skills of goat kids. Pregnant Norwegian dairy goats were exposed to different spatial allowance (namely 1.0, 2.0, or 3.0 m2 per animal) within the commercially applied range during pregnancy and their serum cortisol levels were measured six times within this period. Twenty-six of the kids born entered a three-stage searching task with increasing difficulty when they were 6 weeks old. The tasks included finding a bucket of milk: while moving (stage 1), after moving and disappearing behind a curtain (stage 2), and moving behind a displacement device and the device moving behind a curtain while hiding the bucket (stage 3). We found that prenatal animal density had no effect on the search skills of the offspring, while kids with higher prenatal maternal cortisol levels performed better at the highest stage tested: finding an object after single invisible displacement. At this stage, singleton kids and males performed better than twins and females. Birth weight had no effect at this stage. The findings suggest that maternal cortisol in the observed range had a facilitating effect on cognitive development of goat kids.
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Affiliation(s)
- Judit Vas
- Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway
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11
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Albañil Sánchez JA, da Costa Klosterhoff M, Romano LA, De Martinez Gaspar Martins C. Histological evaluation of vital organs of the livebearer Jenynsia multidentata (Jenyns, 1842) exposed to glyphosate: A comparative analysis of Roundup ® formulations. CHEMOSPHERE 2019; 217:914-924. [PMID: 30471482 DOI: 10.1016/j.chemosphere.2018.11.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 11/01/2018] [Accepted: 11/02/2018] [Indexed: 06/09/2023]
Abstract
Roundup formulations are herbicides whose active principle is glyphosate. However, these formulations are potentially more toxic to non-target organisms than pure glyphosate. This study aimed to evaluate and compare the toxic potential of the Roundup formulations through histological alterations in fish. Thus, males and females of the neotropical fish species Jenynsia multidentata (Jenyns, 1842) were exposed for 24 or 96 h to the Roundup Original® (RO), Roundup Transorb® (RT) or Roundup WG® (RWG) formulations, at a fixed concentration of 0.5 mg/L of glyphosate. This concentration is close to the maximum glyphosate limits found in the environment and is non-lethal to J. multidentata. The three formulations caused histological damage to the liver, gills and brain of J. multidentata, which increased over the exposure time. Differences in the histological alterations between females and males were observed in the liver and brain. Females were more tolerant to RO and RT than RWG. Males did not exhibit these differences in sensitiveness with formulations. The RWG caused more damage in the liver and gills and RT in the brain. Overall, there were differences in the toxicity of RO, RT and RWG and the toxic effect was presented through histological damage, reinforcing the usefulness of histological biomarkers for Roundup® toxicity. The comparison of the toxic potential of glyphosate-based herbicides is important because it could give support to the governmental organizations to set protective rules for the water ecosystems and human health, as well as to reduce the use of highly toxic formulations in agriculture.
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Affiliation(s)
- Jessica Andrea Albañil Sánchez
- Programa de Pós-Graduação em Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Av. Itália km 8, 96203-900, Rio Grande, RS, Brazil
| | - Marta da Costa Klosterhoff
- Instituto de Oceanografia, Universidade Federal do Rio Grande, Av. Itália km 8, 96203-900, Rio Grande, RS, Brazil
| | - Luis Alberto Romano
- Instituto de Oceanografia, Universidade Federal do Rio Grande, Av. Itália km 8, 96203-900, Rio Grande, RS, Brazil
| | - Camila De Martinez Gaspar Martins
- Programa de Pós-Graduação em Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Av. Itália km 8, 96203-900, Rio Grande, RS, Brazil.
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Puga S, Cardoso V, Pinto-Ribeiro F, Pacheco M, Almeida A, Pereira P. Brain morphometric profiles and their seasonal modulation in fish (Liza aurata) inhabiting a mercury contaminated estuary. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 237:318-328. [PMID: 29499575 DOI: 10.1016/j.envpol.2018.02.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/09/2018] [Accepted: 02/16/2018] [Indexed: 06/08/2023]
Abstract
Mercury (Hg) is a potent neurotoxicant known to induce important adverse effects on fish, but a deeper understanding is lacking regarding how environmental exposure affects the brain morphology and neural plasticity of specific brain regions in wild specimens. In this work, it was evaluated the relative volume and cell density of the lateral pallium, hypothalamus, optic tectum and molecular layer of the cerebellum on wild Liza aurata captured in Hg-contaminated (LAR) and non-contaminated (SJ) sites of a coastal system (Ria de Aveiro, Portugal). Given the season-related variations in the environment that fish are naturally exposed, this assessment was performed in the winter and summer. Hg triggered a deficit in cell density of hypothalamus during the winter that could lead to hormonal dysfunctions, while in the summer Hg promoted larger volumes of the optic tectum and cerebellum, indicating the warm period as the most critical for the manifestation of putative changes in visual acuity and motor-dependent tasks. Moreover, in fish from the SJ site, the lateral pallium relative volume and the cell density of the hypothalamus and optic tectum were higher in the winter than in summer. Thus, season-related stimuli strongly influence the size and/or cell density of specific brain regions in the non-contaminated area, pointing out the ability of fish to adapt to environmental and physiological demands. Conversely, fish from the Hg-contaminated site showed a distinct seasonal profile of brain morphology, presenting a larger optic tectum in the summer, as well as a larger molecular layer of the cerebellum with higher cell density. Moreover, Hg exposure impaired the winter-summer variation of the lateral pallium relative size (as observed at SJ). Altogether, seasonal variations in fish neural morphology and physiology should be considered when performing ecotoxicological studies in order to better discriminate the Hg neurotoxicity.
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Affiliation(s)
- Sónia Puga
- Life and Health Sciences Research Institute (ICVS), School of Medicine (EM), Campus of Gualtar, University of Minho, 4750-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
| | - Vera Cardoso
- Life and Health Sciences Research Institute (ICVS), School of Medicine (EM), Campus of Gualtar, University of Minho, 4750-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
| | - Filipa Pinto-Ribeiro
- Life and Health Sciences Research Institute (ICVS), School of Medicine (EM), Campus of Gualtar, University of Minho, 4750-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
| | - Mário Pacheco
- Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Armando Almeida
- Life and Health Sciences Research Institute (ICVS), School of Medicine (EM), Campus of Gualtar, University of Minho, 4750-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
| | - Patrícia Pereira
- Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal.
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Torres-Pérez M, Rosillo JC, Berrosteguieta I, Olivera-Bravo S, Casanova G, García-Verdugo JM, Fernández AS. Stem cells distribution, cellular proliferation and migration in the adult Austrolebias charrua brain. Brain Res 2017; 1673:11-22. [DOI: 10.1016/j.brainres.2017.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 07/27/2017] [Accepted: 08/03/2017] [Indexed: 12/18/2022]
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14
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Pushchina EV, Zharikova EI, Varaksin AA. Persistent and reparative neurogenesis in the juvenile masu salmon Oncorhynchus masou telencephalon after mechanical injury. Russ J Dev Biol 2017. [DOI: 10.1134/s106236041705006x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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DePasquale C, Neuberger T, Hirrlinger AM, Braithwaite VA. The influence of complex and threatening environments in early life on brain size and behaviour. Proc Biol Sci 2016; 283:rspb.2015.2564. [PMID: 26817780 PMCID: PMC4795028 DOI: 10.1098/rspb.2015.2564] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The ways in which challenging environments during development shape the brain and behaviour are increasingly being addressed. To date, studies typically consider only single variables, but the real world is more complex. Many factors simultaneously affect the brain and behaviour, and whether these work independently or interact remains untested. To address this, zebrafish (Danio rerio) were reared in a two-by-two design in housing that varied in structural complexity and/or exposure to a stressor. Fish experiencing both complexity (enrichment objects changed over time) and mild stress (daily net chasing) exhibited enhanced learning and were less anxious when tested as juveniles (between 77 and 90 days). Adults tested (aged 1 year) were also less anxious even though fish were kept in standard housing after three months of age (i.e. no chasing or enrichment). Volumetric measures of the brain using magnetic resonance imaging (MRI) showed that complexity alone generated fish with a larger brain, but this increase in size was not seen in fish that experienced both complexity and chasing, or chasing alone. The results highlight the importance of looking at multiple variables simultaneously, and reveal differential effects of complexity and stressful experiences during development of the brain and behaviour.
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Affiliation(s)
- C DePasquale
- Department of Biology, Pennsylvania State University-Altoona, Altoona, PA, USA Center for Brain, Behavior, and Cognition, Pennsylvania State University, University Park, PA, USA Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA, USA
| | - T Neuberger
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA Department of Bioengineering, Pennsylvania State University, University Park, PA, USA
| | - A M Hirrlinger
- Department of Biology, Pennsylvania State University, University Park, PA, USA
| | - V A Braithwaite
- Center for Brain, Behavior, and Cognition, Pennsylvania State University, University Park, PA, USA Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA, USA Department of Biology, Pennsylvania State University, University Park, PA, USA
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Näslund J, Larsen MH, Thomassen ST, Aarestrup K, Johnsson JI. Environment‐dependent plasticity and ontogenetic changes in the brain of hatchery‐reared Atlantic salmon. J Zool (1987) 2016. [DOI: 10.1111/jzo.12392] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. Näslund
- Department of Biological and Environmental Sciences University of Gothenburg Gothenburg Sweden
| | - M. H. Larsen
- National Institute of Aquatic Resources Section for Freshwater Fisheries and Ecology Technical University of Denmark Silkeborg Denmark
- Danish Centre for Wild Salmon Randers Denmark
| | | | - K. Aarestrup
- National Institute of Aquatic Resources Section for Freshwater Fisheries and Ecology Technical University of Denmark Silkeborg Denmark
| | - J. I. Johnsson
- Department of Biological and Environmental Sciences University of Gothenburg Gothenburg Sweden
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Dunlap KD. Fish Neurogenesis in Context: Assessing Environmental Influences on Brain Plasticity within a Highly Labile Physiology and Morphology. BRAIN, BEHAVIOR AND EVOLUTION 2016; 87:156-166. [DOI: 10.1159/000446907] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Fish have unusually high rates of brain cell proliferation and neurogenesis during adulthood, and the rates of these processes are greatly influenced by the environment. This high level of cell proliferation and its responsiveness to environmental change indicate that such plasticity might be a particularly important mechanism underlying behavioral plasticity in fish. However, as part of their highly labile physiology and morphology, fish also respond to the environment through processes that affect cell proliferation but that are not specific to behavioral change. For example, the environment has nonspecific influences on cell proliferation all over the body via its effect on body temperature and growth rate. In addition, some fish species also have an unusual capacity for sex change and somatic regeneration, and both of these processes likely involve widespread changes in cell proliferation. Thus, in evaluating the possible behavioral role of adult brain cell proliferation, it is important to distinguish regionally specific responses in behaviorally relevant brain nuclei from global proliferative changes across the whole brain or body. In this review, I first highlight how fish differ from other vertebrates, particularly birds and mammals, in ways that have a bearing on the interpretation of brain plasticity. I then summarize the known effects of the physical and social environment, sex change, and predators on brain cell proliferation and neurogenesis, with a particular emphasis on whether the effects are regionally specific. Finally, I review evidence that environmentally induced changes in brain cell proliferation and neurogenesis in fish are mediated by hormones and play a role in behavioral responses to the environment.
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Abstract
Teleost fish have a remarkable neurogenic and regenerative capacity in the adult throughout the rostrocaudal axis of the brain. The distribution of proliferation zones shows a remarkable conservation, even in distantly related teleost species, suggesting a common teleost ground plan of proliferation zones. There are different progenitor populations in the neurogenic niches-progenitors positive for radial glial markers (dorsal telencephalon, hypothalamus) and progenitors with neuroepithelial-like characteristics (ventral telencephalon, optic tectum, cerebellum). Definition of these progenitors has allowed studying their role in normal growth of the adult brain, but also when challenged following a lesion. From these studies, important roles have emerged for intrinsic mechanisms and extrinsic signals controlling the activation of adult neurogenesis that enable regeneration of the adult brain to occur, opening up new perspectives on rekindling regeneration also in the context of the mammalian brain.
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Affiliation(s)
- Julia Ganz
- Institute of Neuroscience, 1254 University of Oregon, Eugene, Oregon 97403
| | - Michael Brand
- Biotechnology Center, and DFG-Research Center for Regenerative Therapies Dresden, Technische Universität Dresden, 01307 Dresden, Germany
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Dunlap KD, Tran A, Ragazzi MA, Krahe R, Salazar VL. Predators inhibit brain cell proliferation in natural populations of electric fish, Brachyhypopomus occidentalis. Proc Biol Sci 2016; 283:20152113. [PMID: 26842566 PMCID: PMC4760157 DOI: 10.1098/rspb.2015.2113] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 01/08/2016] [Indexed: 11/12/2022] Open
Abstract
Compared with laboratory environments, complex natural environments promote brain cell proliferation and neurogenesis. Predators are one important feature of many natural environments, but, in the laboratory, predatory stimuli tend to inhibit brain cell proliferation. Often, laboratory predatory stimuli also elevate plasma glucocorticoids, which can then reduce brain cell proliferation. However, it is unknown how natural predators affect cell proliferation or whether glucocorticoids mediate the neurogenic response to natural predators. We examined brain cell proliferation in six populations of the electric fish, Brachyhypopomus occidentalis, exposed to three forms of predator stimuli: (i) natural variation in the density of predatory catfish; (ii) tail injury, presumably from predation attempts; and (iii) the acute stress of capture. Populations with higher predation pressure had lower density of proliferating (PCNA+) cells, and fish with injured tails had lower proliferating cell density than those with intact tails. However, plasma cortisol did not vary at the population level according to predation pressure or at the individual level according to tail injury. Capture stress significantly increased cortisol, but only marginally decreased cell proliferation. Thus, it appears that the presence of natural predators inhibits brain cell proliferation, but not via mechanisms that depend on changes in basal cortisol levels. This study is the first demonstration of predator-induced alteration of brain cell proliferation in a free-living vertebrate.
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Affiliation(s)
- Kent D Dunlap
- Department of Biology, Trinity College, Hartford, CT 06106, USA
| | - Alex Tran
- Department of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1
| | | | - Rüdiger Krahe
- Department of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1
| | - Vielka L Salazar
- Department of Biology, Cape Breton University, Sydney, Nova Scotia, Canada B1P 6L2
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Herczeg G, Gonda A, Balázs G, Noreikiene K, Merilä J. Experimental evidence for sex-specific plasticity in adult brain. Front Zool 2015; 12:38. [PMID: 26705404 PMCID: PMC4690261 DOI: 10.1186/s12983-015-0130-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 12/15/2015] [Indexed: 01/22/2023] Open
Abstract
Background Plasticity in brain size and the size of different brain regions during early ontogeny is known from many vertebrate taxa, but less is known about plasticity in the brains of adults. In contrast to mammals and birds, most parts of a fish’s brain continue to undergo neurogenesis throughout adulthood, making lifelong plasticity in brain size possible. We tested whether maturing adult three-spined sticklebacks (Gasterosteus aculeatus) reared in a stimulus-poor environment exhibited brain plasticity in response to environmental enrichment, and whether these responses were sex-specific, thus altering the degree of sexual size dimorphism in the brain. Results Relative sizes of total brain and bulbus olfactorius showed sex-specific responses to treatment: males developed larger brains but smaller bulbi olfactorii than females in the enriched treatment. Hence, the degree of sexual size dimorphism (SSD) in relative brain size and the relative size of the bulbus olfactorius was found to be environment-dependent. Furthermore, the enriched treatment induced development of smaller tecta optica in both sexes. Conclusions These results demonstrate that adult fish can alter the size of their brain (or brain regions) in response to environmental stimuli, and these responses can be sex-specific. Hence, the degree of SSD in brain size can be environment-dependent, and our results hint at the possibility of a large plastic component to SSD in stickleback brains. Apart from contributing to our understanding of the processes shaping and explaining variation in brain size and the size of different brain regions in the wild, the results show that provision of structural complexity in captive environments can influence brain development. Assuming that the observed plasticity influences fish behaviour, these findings may also have relevance for fish stocking, both for economical and conservational purposes. Electronic supplementary material The online version of this article (doi:10.1186/s12983-015-0130-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gábor Herczeg
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány1/C, 1117 Budapest, Hungary ; Ecological Genetics Research Unit, Department of Biosciences, FI-00014 University of Helsinki, Helsinki, Finland
| | - Abigél Gonda
- Ecological Genetics Research Unit, Department of Biosciences, FI-00014 University of Helsinki, Helsinki, Finland
| | - Gergely Balázs
- Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány1/C, 1117 Budapest, Hungary
| | - Kristina Noreikiene
- Ecological Genetics Research Unit, Department of Biosciences, FI-00014 University of Helsinki, Helsinki, Finland
| | - Juha Merilä
- Ecological Genetics Research Unit, Department of Biosciences, FI-00014 University of Helsinki, Helsinki, Finland
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D’Aniello B, Polese G, Luongo L, Scandurra A, Magliozzi L, Aria M, Pinelli C. Neuroanatomical relationships between FMRFamide-immunoreactive components of the nervus terminalis and the topology of olfactory bulbs in teleost fish. Cell Tissue Res 2015; 364:43-57. [DOI: 10.1007/s00441-015-2295-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/07/2015] [Indexed: 10/22/2022]
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Transcriptomic responses of Atlantic salmon (Salmo salar) to environmental enrichment during juvenile rearing. PLoS One 2015; 10:e0118378. [PMID: 25742646 PMCID: PMC4350989 DOI: 10.1371/journal.pone.0118378] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 01/15/2015] [Indexed: 12/30/2022] Open
Abstract
Captive rearing programs (hatcheries) are often used in conservation and management efforts for at-risk salmonid fish populations. However, hatcheries typically rear juveniles in environments that contrast starkly with natural conditions, which may lead to phenotypic and/or genetic changes that adversely affect the performance of juveniles upon their release to the wild. Environmental enrichment has been proposed as a mechanism to improve the efficacy of population restoration efforts from captive-rearing programs; in this study, we examine the influence of environmental enrichment during embryo and yolk-sac larval rearing on the transcriptome of Atlantic salmon (Salmo salar). Full siblings were reared in either a hatchery environment devoid of structure or an environment enriched with gravel substrate. At the end of endogenous feeding by juveniles, we examined patterns of gene transcript abundance in head tissues using the cGRASP-designed Agilent 4×44K microarray. Significance analysis of microarrays (SAM) indicated that 808 genes were differentially transcribed between the rearing environments and a total of 184 gene ontological (GO) terms were over- or under-represented in this gene list, several associated with mitosis/cell cycle and muscle and heart development. There were also pronounced differences among families in the degree of transcriptional response to rearing environment enrichment, suggesting that gene-by-environment effects, possibly related to parental origin, could influence the efficacy of enrichment interventions.
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23
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Johnsson JI, Brockmark S, Näslund J. Environmental effects on behavioural development consequences for fitness of captive-reared fishes in the wild. JOURNAL OF FISH BIOLOGY 2014; 85:1946-1971. [PMID: 25469953 DOI: 10.1111/jfb.12547] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 09/23/2014] [Indexed: 06/04/2023]
Abstract
Why do captive-reared fishes generally have lower fitness in natural environments than wild conspecifics, even when the hatchery fishes are derived from wild parents from the local population? A thorough understanding of this question is the key to design artificial rearing environments that optimize post-release performance, as well as to recognize the limitations of what can be achieved by modifying hatchery rearing methods. Fishes are generally very plastic in their development and through gene-environment interactions, epigenetic and maternal effects their phenotypes will develop differently depending on their rearing environment. This suggests that there is scope for modifying conventional rearing environments to better prepare fishes for release into the wild. The complexity of the natural environment is impossible to mimic in full-scale rearing facilities. So, in reality, the challenge is to identify key modifications of the artificial rearing environment that are practically and economically feasible and that efficiently promote development towards a more wild-like phenotype. Do such key modifications really exist? Here, attempts to use physical enrichment and density reduction to improve the performance of hatchery fishes are discussed and evaluated. These manipulations show potential to increase the fitness of hatchery fishes released into natural environments, but the success is strongly dependent on adequately adapting methods to species and life stage-specific conditions.
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Affiliation(s)
- J I Johnsson
- University of Gothenburg, Department of Biological and Environmental Sciences, Box 463, SE 405 30 Gothenburg, Sweden
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24
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Lecchini D, Lecellier G, Lanyon RG, Holles S, Poucet B, Duran E. Variation in Brain Organization of Coral Reef Fish Larvae according to Life History Traits. BRAIN, BEHAVIOR AND EVOLUTION 2014; 83:17-30. [DOI: 10.1159/000356787] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 10/22/2013] [Indexed: 11/19/2022]
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Batzina A, Dalla C, Papadopoulou-Daifoti Z, Karakatsouli N. Effects of environmental enrichment on growth, aggressive behaviour and brain monoamines of gilthead seabream Sparus aurata reared under different social conditions. Comp Biochem Physiol A Mol Integr Physiol 2013; 169:25-32. [PMID: 24326244 DOI: 10.1016/j.cbpa.2013.12.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 12/02/2013] [Accepted: 12/04/2013] [Indexed: 10/25/2022]
Abstract
The presence of blue or red-brown substrate on the tank bottom has been previously reported as an efficient means of environmental enrichment for gilthead seabream. The present study aimed to investigate whether this enrichment is still beneficial when gilthead seabream is reared under different social conditions (i.e. a lower 4.9 kg m(-3) and a higher 9.7 kg m(-3) density). Water exchange was adjusted according to fish biomass to exclude density effects on water quality. In the enriched tanks single-colour glass gravel was used as substrate (blue and red-brown substrate, or BS and RBS respectively), while control tanks had no gravel. Growth, aggressive behaviour and size distribution results indicated that the lower density created a less favourable social environment. In both densities studied, BS enhanced growth, suppressed aggression and reduced brain serotonergic activity. In the condition of intense social interactions (i.e. the lower density) BS also reduced brain dopaminergic activity. These results along with the negative correlations observed between brain monoamines and fish body mass, indicated that substrate and density effects are socially-induced. However, there may be several biotic and/or abiotic factors interfering with substrate effects that should be investigated before the practical use of a substrate in land-based intensive aquaculture.
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Affiliation(s)
- Alkisti Batzina
- Department of Applied Hydrobiology, Faculty of Animal Science and Aquaculture, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece
| | - Christina Dalla
- Department of Pharmacology, Medical School, University of Athens, Mikras Asias 75, 115 27 Goudi, Athens, Greece
| | - Zeta Papadopoulou-Daifoti
- Department of Pharmacology, Medical School, University of Athens, Mikras Asias 75, 115 27 Goudi, Athens, Greece
| | - Nafsika Karakatsouli
- Department of Applied Hydrobiology, Faculty of Animal Science and Aquaculture, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
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26
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Gonda A, Herczeg G, Merilä J. Evolutionary ecology of intraspecific brain size variation: a review. Ecol Evol 2013; 3:2751-64. [PMID: 24567837 PMCID: PMC3930043 DOI: 10.1002/ece3.627] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 12/24/2022] Open
Abstract
The brain is a trait of central importance for organismal performance and fitness. To date, evolutionary studies of brain size variation have mainly utilized comparative methods applied at the level of species or higher taxa. However, these studies suffer from the difficulty of separating causality from correlation. In the other extreme, studies of brain plasticity have focused mainly on within-population patterns. Between these extremes lie interpopulational studies, focusing on brain size variation among populations of the same species that occupy different habitats or selective regimes. These studies form a rapidly growing field of investigations which can help us to understand brain evolution by providing a test bed for ideas born out of interspecific studies, as well as aid in uncovering the relative importance of genetic and environmental factors shaping variation in brain size and architecture. Aside from providing the first in depth review of published intraspecific studies of brain size variation, we discuss the prospects embedded with interpopulational studies of brain size variation. In particular, the following topics are identified as deserving further attention: (i) studies focusing on disentangling the contributions of genes, environment, and their interactions on brain variation within and among populations, (ii) studies applying quantitative genetic tools to evaluate the relative importance of genetic and environmental factors on brain features at different ontogenetic stages, (iii) apart from utilizing simple gross estimates of brain size, future studies could benefit from use of neuroanatomical, neurohistological, and/or molecular methods in characterizing variation in brain size and architecture. Evolution of brain size and architecture is a widely studied topic. However, the majority of studies are interspecific and comparative. Here we summarize the recently growing body of intraspecific studies based on population comparisons and outline the future potential in this approach.
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Affiliation(s)
- Abigél Gonda
- Ecological Genetics Research UnitDepartment of Biosciences, University of HelsinkiP.O. Box 65, FI-00014, Helsinki, Finland
| | - Gábor Herczeg
- Ecological Genetics Research UnitDepartment of Biosciences, University of HelsinkiP.O. Box 65, FI-00014, Helsinki, Finland
- Behavioural Ecology GroupDepartment of Systematic Zoology and Ecology, Eötvös Loránd UniversityPázmány Péter sétány 1/C, H-1117, Budapest, Hungary
| | - Juha Merilä
- Ecological Genetics Research UnitDepartment of Biosciences, University of HelsinkiP.O. Box 65, FI-00014, Helsinki, Finland
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Salvanes AGV, Moberg O, Ebbesson LOE, Nilsen TO, Jensen KH, Braithwaite VA. Environmental enrichment promotes neural plasticity and cognitive ability in fish. Proc Biol Sci 2013; 280:20131331. [PMID: 23902903 DOI: 10.1098/rspb.2013.1331] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Different kinds of experience during early life can play a significant role in the development of an animal's behavioural phenotype. In natural contexts, this influences behaviours from anti-predator responses to navigation abilities. By contrast, for animals reared in captive environments, the homogeneous nature of their experience tends to reduce behavioural flexibility. Studies with cage-reared rodents indicate that captivity often compromises neural development and neural plasticity. Such neural and behavioural deficits can be problematic if captive-bred animals are being reared with the intention of releasing them as part of a conservation strategy. Over the last decade, there has been growing interest in the use of environmental enrichment to promote behavioural flexibility in animals that are bred for release. Here, we describe the positive effects of environmental enrichment on neural plasticity and cognition in juvenile Atlantic salmon (Salmo salar). Exposing fish to enriched conditions upregulated the forebrain expression of NeuroD1 mRNA and improved learning ability assessed in a spatial task. The addition of enrichment to the captive environment thus promotes neural and behavioural changes that are likely to promote behavioural flexibility and improve post-release survival.
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28
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Maruska KP, Carpenter RE, Fernald RD. Characterization of cell proliferation throughout the brain of the African cichlid fish Astatotilapia burtoni and its regulation by social status. J Comp Neurol 2013; 520:3471-91. [PMID: 22431175 DOI: 10.1002/cne.23100] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
New cells are added in the brains of all adult vertebrates, but fishes have some of the greatest potential for neurogenesis and gliogenesis among all taxa, partly due to their indeterminate growth. Little is known, however, about how social interactions influence cell proliferation in the brain of these fishes that comprise the largest group of vertebrates. We used 5-bromo-2'-deoxyuridine (BrdU) to identify and localize proliferation zones in the telencephalon, diencephalon, mesencephalon, and rhombencephalon that were primarily associated with ventricular surfaces in the brain of the African cichlid fish Astatotilapia burtoni. Cell migration was evident in some regions by 1 day post injection, and many newborn cells coexpressed the neuronal marker HuC/D at 30 days, suggesting they had differentiated into neurons. To test the hypothesis that social status and perception of an opportunity to rise in rank influenced cell proliferation, we compared numbers of BrdU-labeled cells in multiple brain nuclei among fish of different social status. Socially suppressed subordinate males had the lowest numbers of proliferating cells in all brain regions examined, but males that were given an opportunity to rise in status had higher cell proliferation rates within 1 day, suggesting rapid upregulation of brain mitotic activity associated with this social transition. Furthermore, socially isolated dominant males had similar numbers of BrdU-labeled cells compared with dominant males that were housed in a socially rich environment, suggesting that isolation has little effect on proliferation and that reduced proliferation in subordinates is a result of the social subordination. These results suggest that A. burtoni will be a useful model to analyze the mechanisms of socially induced neurogenesis in vertebrates.
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Affiliation(s)
- Karen P Maruska
- Department of Biology, Stanford University, Stanford, California 94305, USA.
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29
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Grassie C, Braithwaite VA, Nilsson J, Nilsen TO, Teien HC, Handeland SO, Stefansson SO, Tronci V, Gorissen M, Flik G, Ebbesson LOE. Aluminum exposure impacts brain plasticity and behavior in Atlantic salmon (Salmo salar). J Exp Biol 2013; 216:3148-55. [DOI: 10.1242/jeb.083550] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
Aluminum (Al) toxicity occurs frequently in natural aquatic ecosystems as a result of acid deposition and natural weathering processes. Detrimental effects of Al toxicity on aquatic organisms are well known and can have consequences for survival. Fish exposed to Al in low pH waters will experience physiological and neuroendocrine changes that disrupt homeostasis and alter behavior. To investigate the effects of Al exposure to both brain and behavior, Atlantic salmon (Salmo salar) kept in water treated with Al (pH 5.7, 0.37±0.04 µmol 1-1 of Al) for 2 weeks were compared to fish kept in a control condition (pH 6.7, <0.04 µmol 1-1 of Al). Fish exposed to Al and acidic conditions had increased Al accumulation in the gills and decreased gill Na+, K+-ATPase activity, which impaired osmoreguatory capacity and caused physiological stress, indicated by elevated plasma cortisol and glucose levels. Here we show for the first time that exposure to Al in acidic conditions also impaired learning performance in a maze task. Al toxicity reduced the expression of NeuroD1 transcript levels in the forebrain of exposed fish. As in mammals, these data show that exposure to chronic stress, such as acidified Al, can reduce neural plasticity during behavioral challenges in salmon, and may impair coping ability to new environments.
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Ebbesson LOE, Braithwaite VA. Environmental effects on fish neural plasticity and cognition. JOURNAL OF FISH BIOLOGY 2012; 81:2151-2174. [PMID: 23252732 DOI: 10.1111/j.1095-8649.2012.03486.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Most fishes experiencing challenging environments are able to adjust and adapt their physiology and behaviour to help them cope more effectively. Much of this flexibility is supported and influenced by cognition and neural plasticity. The understanding of fish cognition and the role played by different regions of the brain has improved significantly in recent years. Techniques such as lesioning, tract tracing and quantifying changes in gene expression help in mapping specialized brain areas. It is now recognized that the fish brain remains plastic throughout a fish's life and that it continues to be sensitive to environmental challenges. The early development of fish brains is shaped by experiences with the environment and this can promote positive and negative effects on both neural plasticity and cognitive ability. This review focuses on what is known about the interactions between the environment, the telencephalon and cognition. Examples are used from a diverse array of fish species, but there could be a lot to be gained by focusing research on neural plasticity and cognition in fishes for which there is already a wealth of knowledge relating to their physiology, behaviour and natural history, e.g. the Salmonidae.
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Affiliation(s)
- L O E Ebbesson
- Uni Research AS, Thormøhlensgate 49B, 5006 Bergen, Norway.
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31
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Fraser TWK, Fjelldal PG, Skjæraasen JE, Hansen T, Mayer I. Triploidy alters brain morphology in pre-smolt Atlantic salmon Salmo salar: possible implications for behaviour. JOURNAL OF FISH BIOLOGY 2012; 81:2199-2212. [PMID: 23252734 DOI: 10.1111/j.1095-8649.2012.03479.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Total brain mass and the volumes of five specific brain regions in diploid and triploid Atlantic salmon Salmo salar pre-smolts were measured using digital images. There were no significant differences (P > 0·05) in total brain mass when corrected for fork length, or the volumes of the optic tecta or hypothalamus when corrected for brain mass, between diploids and triploids. There was a significant effect (P < 0·01) of ploidy on the volume of the olfactory bulb, with it being 9·0% larger in diploids compared with triploids. The cerebellum and telencephalon, however, were significantly larger, 17 and 8% respectively, in triploids compared with diploids. Sex had no significant effect (P > 0·05) on total brain mass or the volumes of any measured brain region. As the olfactory bulbs, cerebellum and telencephalon are implicated in a number of functions, including foraging ability, aggression and spatial cognition, these results may explain some of the behavioural differences previously reported between diploids and triploids.
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Affiliation(s)
- T W K Fraser
- Department of Production Animal Clinical Sciences, Norwegian School of Veterinary Science, 0033 Oslo, Norway.
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Dunlap KD, Chung M. Social novelty enhances brain cell proliferation, cell survival, and chirp production in an electric fish, Apteronotus leptorhynchus. Dev Neurobiol 2012; 73:324-32. [PMID: 23076841 DOI: 10.1002/dneu.22063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 10/10/2012] [Accepted: 10/11/2012] [Indexed: 12/12/2022]
Abstract
For many animals, enriched environments and social interaction promote adult neurogenesis. However, in some cases, the effect is transient, and long-term environmental stimuli have little benefit for neurogenesis. In electric fish, Apteronotus leptorhynchus, fish housed in pairs for 7 days show higher density of newborn brain cells (cell addition) than isolated fish, but fish paired for 14 days have rates of cell addition similar to isolated controls. We examined whether introduction of social novelty can sustain elevated levels of cell addition and prevent long-term habituation to social interaction. We also monitored electrocommunication signals ("chirps") as a measure of the behavioral response to social novelty. We paired fish for 14 days with one continuous partner (no social novelty), two sequential partners changed after 7 days (low novelty) or seven sequential partners changed every 2 days (high novelty). On Day 11, we injected fish with BrdU, sacrificed fish 3 days later and quantified BrdU labeling in the diencephalic periventricular zone. Fish exposed to no novelty had BrdU labeling similar to isolated fish. Fish with low novelty showed small increases in BrdU labeling and those with high novelty had much greater BrdU labeling. Similarly, chirp rates were greater in fish with low novelty than with no novelty and greatest yet in fish with high novelty. By varying the timing of novelty relative to BrdU injection, we showed that social novelty promoted both proliferation and survival of newborn cells. These results indicated that brain cell proliferation and survival is influenced more by social change than simply the presence of social stimuli.
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Affiliation(s)
- Kent D Dunlap
- Department of Biology, Trinity College, Hartford, Connecticut 06106, USA.
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Sørensen C, Nilsson GE, Summers CH, Øverli Ø. Social stress reduces forebrain cell proliferation in rainbow trout (Oncorhynchus mykiss). Behav Brain Res 2012; 227:311-8. [DOI: 10.1016/j.bbr.2011.01.041] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Revised: 01/10/2011] [Accepted: 01/25/2011] [Indexed: 11/26/2022]
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von Krogh K, Sørensen C, Nilsson GE, Øverli Ø. Forebrain cell proliferation, behavior, and physiology of zebrafish, Danio rerio, kept in enriched or barren environments. Physiol Behav 2010; 101:32-9. [DOI: 10.1016/j.physbeh.2010.04.003] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 03/31/2010] [Accepted: 04/01/2010] [Indexed: 11/26/2022]
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Neuroendocrinology of sexual plasticity in teleost fishes. Front Neuroendocrinol 2010; 31:203-16. [PMID: 20176046 PMCID: PMC2885357 DOI: 10.1016/j.yfrne.2010.02.002] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 02/12/2010] [Accepted: 02/13/2010] [Indexed: 01/01/2023]
Abstract
The study of sex differences has produced major insights into the organization of animal phenotypes and the regulatory mechanisms generating phenotypic variation from similar genetic templates. Teleost fishes display the greatest diversity of sexual expression among vertebrate animals. This diversity appears to arise from diversity in the timing of sex determination and less functional interdependence among the components of sexuality relative to tetrapod vertebrates. Teleost model systems therefore provide powerful models for understanding gonadal and non-gonadal influences on behavioral and physiological variation. This review addresses socially-controlled sex change and alternate male phenotypes in fishes. These sexual patterns are informative natural experiments that illustrate how variation in conserved neuroendocrine pathways can give rise to a wide range of reproductive adaptations. Key regulatory factors underlying sex change and alternative male phenotypes that have been identified to date include steroid hormones and the neuropeptides GnRH and arginine vasotocin, but genomic approaches are now implicating a diversity of other influences as well.
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Gonda A, Herczeg G, Merilä J. Habitat-dependent and -independent plastic responses to social environment in the nine-spined stickleback (Pungitius pungitius) brain. Proc Biol Sci 2009; 276:2085-92. [PMID: 19324759 DOI: 10.1098/rspb.2009.0026] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The influence of environmental complexity on brain development has been demonstrated in a number of taxa, but the potential influence of social environment on neural architecture remains largely unexplored. We investigated experimentally the influence of social environment on the development of different brain parts in geographically and genetically isolated and ecologically divergent populations of nine-spined sticklebacks (Pungitius pungitius). Fish from two marine and two pond populations were reared in the laboratory from eggs to adulthood either individually or in groups. Group-reared pond fish developed relatively smaller brains than those reared individually, but no such difference was found in marine fish. Group-reared fish from both pond and marine populations developed larger tecta optica and smaller bulbi olfactorii than individually reared fish. The fact that the social environment effect on brain size differed between marine and pond origin fish is in agreement with the previous research, showing that pond fish pay a high developmental cost from grouping while marine fish do not. Our results demonstrate that social environment has strong effects on the development of the stickleback brain, and on the brain's sensory neural centres in particular. The potential adaptive significance of the observed brain-size plasticity is discussed.
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Affiliation(s)
- Abigél Gonda
- Ecological Genetic Research Unit, Department of Biological and Environmental Sciences, University of Helsinki, PO Box 65, 00014 Helsinki, Finland.
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Lema SC, Dickey JT, Schultz IR, Swanson P. Dietary exposure to 2,2',4,4'-tetrabromodiphenyl ether (PBDE-47) alters thyroid status and thyroid hormone-regulated gene transcription in the pituitary and brain. ENVIRONMENTAL HEALTH PERSPECTIVES 2008; 116:1694-9. [PMID: 19079722 PMCID: PMC2599765 DOI: 10.1289/ehp.11570] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Accepted: 08/01/2008] [Indexed: 05/05/2023]
Abstract
BACKGROUND Polybrominated diphenyl ether (PBDE) flame retardants have been implicated as disruptors of the hypothalamic-pituitary-thyroid axis. Animals exposed to PBDEs may show reduced plasma thyroid hormone (TH), but it is not known whether PBDEs impact TH-regulated pathways in target tissues. OBJECTIVE We examined the effects of dietary exposure to 2,2',4,4'-tetrabromodiphenyl ether (PBDE-47)-commonly the highest concentrated PBDE in human tissues-on plasma TH levels and on gene transcripts for glycoprotein hormone alpha-subunit (GPHalpha) and thyrotropin beta-subunit (TSHbeta) in the pituitary gland, the auto-induced TH receptors alpha and beta in the brain and liver, and the TH-responsive transcription factor basic transcription element-binding protein (BTEB) in the brain. METHODS Breeding pairs of adult fathead minnows (Pimephales promelas) were given dietary PBDE-47 at two doses (2.4 microg/pair/day or 12.3 microg/pair/day) for 21 days. RESULTS Minnows exposed to PBDE-47 had depressed plasma thyroxine (T(4)), but not 3,5,3'-triiodothyronine (T(3)). This decline in T(4) was accompanied by elevated mRNA levels for TStHbeta (low dose only) in the pituitary. PBDE-47 intake elevated transcript for TH receptor alpha in the brain of females and decreased mRNA for TH receptor beta in the brain of both sexes, without altering these transcripts in the liver. In males, PBDE-47 exposure also reduced brain transcripts for BTEB. CONCLUSIONS Our results indicate that dietary exposure to PBDE-47 alters TH signaling at multiple levels of the hypothalamic-pituitary-thyroid axis and provide evidence that TH-responsive pathways in the brain may be particularly sensitive to disruption by PBDE flame retardants.
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Affiliation(s)
- Sean C. Lema
- Physiology Program, Northwest Fisheries Science Center, National Oceanic and Atmospheric Administration, Seattle, Washington, USA
- Address correspondence to S.C. Lema, Biology and Marine Biology, University of North Carolina-Wilmington, 601 S. College Rd., Wilmington, NC 28403 USA. Telephone: (910) 962–2514. Fax: (910) 962-4066. E-mail:
| | - Jon T. Dickey
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, USA
| | - Irvin R. Schultz
- Marine Sciences Laboratory, Battelle, Pacific Northwest National Laboratory, Sequim, Washington, USA
| | - Penny Swanson
- Physiology Program, Northwest Fisheries Science Center, National Oceanic and Atmospheric Administration, Seattle, Washington, USA
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Ramírez-Duarte WF, Rondón-Barragán IS, Eslava-Mocha PR. Acute toxicity and histopathological alterations of Roundup® herbicide on "cachama blanca" (Piaractus brachypomus). PESQUISA VETERINARIA BRASILEIRA 2008. [DOI: 10.1590/s0100-736x2008001100002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Acute toxicity of the glyphosate -N (phosphonomethyl) glycine- herbicide, Roundup®, in juveniles of cachama blanca, (Piaractus brachypomus), was evaluated and the histopathological lesions were assessed. The 96 h lethal concentration 50 was 97.47mg.L-1 (P<0.05). In the gill, necrotic and proliferative lesions were detected. In the liver, congestion, degenerative foci, hyaline droplets and lipidic vacuolization of the hepatocytes were observed. In the stomach mild hyperplasia of mucous cells was detected, which was also observed in the skin. In this latter tissue, a large increase in the thickness of the epidermis with necrotic lesions, infiltration of leukocytes and melanin pigment were observed. In the brain, degenerative foci of neuronal bodies in the telencephalon associated with gliosis and infiltration of eosinophilic granule cells/mast cells were shown. In conclusion, gills, liver, skin and brain are susceptible to Roundup®. Moreover, effects on the central nervous system could affect olfaction as well as individual and group behavior, the reproductive performance of the fish and hence have repercussions at the population level.
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Lema SC, Nevitt GA. Testing an ecophysiological mechanism of morphological plasticity in pupfish and its relevance to conservation efforts for endangered Devils Hole pupfish. ACTA ACUST UNITED AC 2006; 209:3499-509. [PMID: 16943490 DOI: 10.1242/jeb.02417] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Imperiled species that have been translocated or established in captivity can show rapid alterations in morphology and behavior, but the proximate mechanisms of such phenotypic changes are rarely known. Devils Hole pupfish (Cyprinodon diabolis) are endemic to a single desert pool and are characterized by a small body, large head and eyes, and lack of pelvic fins. To lessen the risk of extinction, additional populations of C. diabolis were established in artificial refuges. Yet, pupfish in these refuges rapidly shifted to a larger body, smaller head and eyes, and greater body depth. Here we examined how food availability and temperature, which differ between these habitats, influence morphological development in closely related Amargosa River pupfish (Cyprinodon nevadensis amargosae). We were interested in knowing whether these environmental factors could developmentally shift Amargosa River pupfish toward the morphology typical of pupfish in Devil's Hole. By regulating food ration, we created groups of pupfish with low, medium and high growth rates. Pupfish with low growth showed proportionally larger head and eyes, smaller body depth, and reduction in pelvic fin development. Elevated temperature further inhibited pelvic fin development in all treatments. Pupfish in the low growth group also showed reduced levels of thyroid hormone, suggesting a possible physiological mechanism underlying these morphological changes. To test this mechanism further, pupfish were reared with goitrogens to pharmacologically inhibit endogenous thyroid hormone production. Pupfish given goitrogens developed larger heads and eyes, shallower bodies, and reduced pelvic fins. Taken together, our results suggest that changes in environmental factors affecting the growth and thyroid hormone status of juvenile pupfish may play a developmental role in generating the morphological differences between C. diabolis in Devil's Hole and the refuges. These findings illustrate the need to incorporate a mechanistic understanding of phenotypic plasticity into conservation strategies to preserve imperiled fishes.
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Affiliation(s)
- Sean C Lema
- Center for Animal Behavior and Section of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA 95616, USA.
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Forlano PM, Schlinger BA, Bass AH. Brain aromatase: new lessons from non-mammalian model systems. Front Neuroendocrinol 2006; 27:247-74. [PMID: 16828853 DOI: 10.1016/j.yfrne.2006.05.002] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Revised: 05/11/2006] [Accepted: 05/16/2006] [Indexed: 01/29/2023]
Abstract
This review highlights recent studies of the anatomical and functional implications of brain aromatase (estrogen synthase) expression in two vertebrate lineages, teleost fishes and songbirds, that show remarkably high levels of adult brain aromatase activity, protein and gene expression compared to other vertebrate groups. Teleosts and birds have proven to be important neuroethological models for investigating how local estrogen synthesis leads to changes in neural phenotypes that translate into behavior. Region-specific patterns of aromatase expression, and thus estrogen synthesis, include the vocal and auditory circuits that figure prominently into the life history adaptations of vocalizing teleosts and songbirds. Thus, by targeting, for example, vocal motor circuits without inappropriate steroid exposure to other steroid-dependent circuits, such as those involved in either copulatory or spawning behaviors, the neuroendocrine system can achieve temporal and spatial specificity in its modulation of neural circuits that lead to the performance of any one behavior.
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Affiliation(s)
- Paul M Forlano
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA.
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Lema SC. Population divergence in plasticity of the AVT system and its association with aggressive behaviors in a Death Valley pupfish. Horm Behav 2006; 50:183-93. [PMID: 16624314 DOI: 10.1016/j.yhbeh.2006.02.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Revised: 02/14/2006] [Accepted: 02/27/2006] [Indexed: 11/22/2022]
Abstract
Behavioral differences can evolve rapidly in allopatry, but little is known about the neural bases of such changes. Allopatric populations of Amargosa pupfish (Cyprinodon nevadensis) vary in aggression and courtship behaviors in the wild. Two of these wild populations were recently found to differ in brain expression of arginine vasotocin (AVT)--a peptide hormone shown previously to modulate aggression in pupfish. These populations have been isolated for less than 4000 years, so it remained unclear whether the differences in behavior and neural AVT phenotype were evolved changes or plastic responses to ecologically dissimilar habitats. Here, I tested whether these population differences have a genetic basis by examining how aggressive behavior and neural AVT phenotype responded to ecologically relevant variation in salinity (0.4 ppt or 3 ppt) and temperature (stable or daily fluctuating). Pupfish from Big Spring were more aggressive than pupfish from the Amargosa River when bred and reared under common laboratory conditions. Morphometric analysis of preoptic AVT immunoreactivity showed that the populations differed in how the AVT system responded to salinity and temperature conditions, and revealed that this plasticity differed between parvocellular and magnocellular AVT neuron groups. Both populations also showed relationships between neural AVT phenotype and aggression in the rearing environment, although populations differed in how aggression related to variation in magnocellular AVT neuron size. Together, these results demonstrate that the pupfish populations have diverged in how physical and social conditions affect the AVT system, and provide evidence that the AVT system can evolve quickly to ecologically dissimilar environments.
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Affiliation(s)
- Sean C Lema
- Center for Animal Behavior, University of California, One Shields Avenue, Davis, CA 95616, USA.
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Kihslinger RL, Lema SC, Nevitt GA. Environmental rearing conditions produce forebrain differences in wild Chinook salmon Oncorhynchus tshawytscha. Comp Biochem Physiol A Mol Integr Physiol 2006; 145:145-51. [PMID: 16890467 DOI: 10.1016/j.cbpa.2006.06.041] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Revised: 03/16/2006] [Accepted: 03/25/2006] [Indexed: 11/17/2022]
Abstract
Recent studies suggest that hatchery-reared fish can have smaller brain-to-body size ratios than wild fish. It is unclear, however, whether these differences are due to artificial selection or instead reflect differences in rearing environment during development. Here we explore how rearing conditions influence the development of two forebrain structures, the olfactory bulb and the telencephalon, in juvenile Chinook salmon (Oncorhynchus tshawytscha) spawned from wild-caught adults. First, we compared the sizes of the olfactory bulb and telencephalon between salmon reared in a wild stream vs. a conventional hatchery. We next compared the sizes of forebrain structures between fish reared in an enriched NATURES hatchery and fish reared in a conventional hatchery. All fish were size-matched and from the same genetic cohort. We found that olfactory bulb and telencephalon volumes relative to body size were significantly larger in wild fish compared to hatchery-reared fish. However, we found no differences between fish reared in enriched and conventional hatchery treatments. Our results suggest that significant differences in the volume of the olfactory bulb and telencephalon between hatchery and wild-reared fish can occur within a single generation.
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Affiliation(s)
- R L Kihslinger
- Section of Neurobiology, Physiology and Behavior, University of California, Davis, One Shields Avenue Davis, CA 95616, USA.
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Kihslinger RL, Nevitt GA. Early rearing environment impacts cerebellar growth in juvenile salmon. J Exp Biol 2006; 209:504-9. [PMID: 16424100 DOI: 10.1242/jeb.02019] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
The size and structure of an animal's brain is typically assumed to result from either natural or artificial selection pressures over generations. However, because a fish's brain grows continuously throughout life, it may be particularly responsive to the environmental conditions the fish experiences during development. Salmon are an ideal model system for studying these effects because natural habitats differ significantly from the hatchery environments in which these fish are frequently reared. For example, in the wild, salmon alevins (i.e. yolk-sac fry) are buried in the gravel, while hatchery environments lack this structural component. We show that the simple manipulation of adding stones to a standard rearing tank can dramatically alter the growth of specific brain structures in steelhead salmon alevins(Oncorhynchus mykiss). We found that alevins reared with stones grew brains with significantly larger cerebella than genetically similar fish reared in conventional tanks. This shift to a larger cerebellar size was, in turn, accompanied by changes in locomotory behaviors - behaviors that correlate strongly to the function of this brain region. We next show that hatchery fish reared in a more naturalistic setting in the wild had significantly larger brains than their lab-reared counterparts. However,relative cerebellar volumes were similar between wild-reared alevins and those reared in the complex treatment in the laboratory. Together our results indicate that, within the first three weeks of life, variation in rearing environment can result in brain differences that are commonly attributed to generations of selection. These results highlight the need to consider enrichment strategies when designing captive rearing facilities for both conservation and laboratory use.
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