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Abstract
The non-destructive collection of ultrathin sections on silicon wafers for post-embedding staining and volumetric correlative light and electron microscopy traditionally requires exquisite manual skills and is tedious and unreliable. In MagC introduced here, sample blocks are augmented with a magnetic resin enabling the remote actuation and collection of hundreds of sections on wafer. MagC allowed the correlative visualization of neuroanatomical tracers within their ultrastructural volumetric electron microscopy context.
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Affiliation(s)
- Thomas Templier
- Institute of NeuroinformaticsUniversity of Zurich and ETH ZurichZurichSwitzerland
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Vaaga CE, Miller KE, Bodor ÁL, Perkel DJ. Expression of the potassium-chloride co-transporter, KCC2, within the avian song system. J Comp Neurol 2018; 526:944-956. [PMID: 29218745 DOI: 10.1002/cne.24372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 11/29/2017] [Accepted: 11/30/2017] [Indexed: 11/06/2022]
Abstract
Songbirds learn to produce vocalizations early in life by listening to, then copying the songs of conspecific males. The anterior forebrain pathway, homologous to a basal ganglia-forebrain circuit, is essential for song learning. The projection between the striato-pallidal structure, Area X, and the medial portion of the dorsolateral thalamic nucleus (DLM) is strongly hyperpolarizing in adults, due to a very negative chloride reversal potential (Person & Perkel, Neuron 46:129-140, 2005). The chloride reversal potential is determined, in part, by the expression level of a neuron-specific potassium-chloride cotransporter, KCC2, which is developmentally upregulated in mammals. To determine whether a similar upregulation in KCC2 expression occurs at the Area X to DLM synapse during development, we examined the expression level of KCC2 in adult zebra finches across the song system as well as during development in the Area X - DLM synapse. We demonstrate that KCC2 is expressed in a subset of neurons throughout the song system, including HVC (used as a proper name), robust nucleus of the arcopallium (RA), lateral magnocellular nucleus of the anterior nidopallium (LMAN), Area X, and DLM. The majority of pallidal-like projection neurons in Area X showed KCC2 immunoreactivity. In adults, KCC2 expression was robust within DLM, and was upregulated between 14 and 24 days post hatching, before the onset of song learning. Light and electron microscopic analysis indicated that KCC2 immunoreactivity is strongly associated with the plasma membrane. Thus, in the song system as in the mammalian brain, KCC2 expression is well placed to modulate the GABAA reversal potential.
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Affiliation(s)
- Christopher E Vaaga
- Departments of Biology and Otolaryngology, University of Washington, Seattle, Washington
| | - Kimberly E Miller
- Departments of Biology and Otolaryngology, University of Washington, Seattle, Washington
| | - Ágnes L Bodor
- Departments of Biology and Otolaryngology, University of Washington, Seattle, Washington
| | - David J Perkel
- Departments of Biology and Otolaryngology, University of Washington, Seattle, Washington
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Morran SAM, Elliott JE, Young JML, Eng ML, Basu N, Williams TD. Ecologically-relevant exposure to methylmercury during early development does not affect adult phenotype in zebra finches (Taeniopygia guttata). Ecotoxicology 2018; 27:259-266. [PMID: 29313303 DOI: 10.1007/s10646-017-1890-4] [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] [Accepted: 12/16/2017] [Indexed: 06/07/2023]
Abstract
Methylmercury causes behavioural and reproductive effects in adult mammals via early developmental exposure. Similar studies in birds are limited and mostly focussed on aquatic systems, but recent work has reported high blood mercury concentrations in terrestrial, passerine songbirds. We used the zebra finch (Taeniopygia guttata) as a model to explore the long-term effects of early developmental exposure to methylmercury exposure. Chicks were dosed orally with either the vehicle control, 0.0315 µg Hg/g bw/day, or 0.075 µg Hg/g bw/day throughout the nestling period (days 1-21 post-hatching). We then measured (a) short-term effects on growth, development, and behaviour (time to self-feeding, neophobia) until 30 days of age (independence), and (b) long-term effects on courtship behaviour and song (males) and reproduction (females) once methylmercury-exposed birds reached sexual maturity (90 days post-hatching). High methylmercury treated birds had mean blood mercury of 0.734 ± 0.163 µg/g at 30 days post-hatching, within the range of values reported for field-sampled songbirds at mercury contaminated sites. However, there were no short-term effects of treatment on growth, development, and behaviour of chicks, and no long-term effects on courtship behaviour and song in males or reproductive performance in females. These results suggest that the nestling period is not a critical window for sensitivity to mercury exposure in zebra finches. Growing nestlings can reduce blood mercury levels through somatic growth and depuration into newly growing feathers, and as a result they might actually be less susceptible compared to adult birds receiving the same level of exposure.
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Affiliation(s)
- Spencer A M Morran
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - John E Elliott
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
- Environment and Climate Change Canada, Science & Technology Branch, Pacific Wildlife Research Centre, Delta, BC, Canada
| | - Jessica M L Young
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Margaret L Eng
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
- University of Saskatchewan, Saskatoon, SK, Canada
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Ste. Anne de Bellevue, QC, Canada
| | - Tony D Williams
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.
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Chin SY, Hopkins WA, Cristol DA. Mercury alters initiation and construction of nests by zebra finches, but not incubation or provisioning behaviors. Ecotoxicology 2017; 26:1271-1283. [PMID: 29022240 DOI: 10.1007/s10646-017-1852-x] [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] [Accepted: 08/30/2017] [Indexed: 06/07/2023]
Abstract
Mercury is an environmental contaminant that impairs avian reproduction, but the behavioral and physiological mechanisms underlying this effect are poorly understood. The objective of this study was to determine whether lifetime dietary exposure to mercury (1.2 µg/g wet weight in food) impacted avian parental behaviors, and how this might influence reproductive success. To distinguish between the direct effects of mercury on parents and offspring, we created four treatment groups of captive-bred zebra finches (Taeniopygia guttata), with control and mercury-exposed adults raising cross-fostered control or mercury-exposed eggs (from maternal transfer). Control parents were 23% more likely to fledge young than parents exposed to mercury, regardless of egg exposure. Mercury-exposed parents were less likely to initiate nests than controls and spent less time constructing them. Nests of mercury-exposed pairs were lighter, possibly due to an impaired ability to bring nest material into the nestbox. However, nest temperature, incubation behavior, and provisioning rate did not differ between parental treatments. Unexposed control eggs tended to have shorter incubation periods and higher hatching success than mercury-exposed eggs, but there was no effect of parental exposure on these parameters. We accidentally discovered that parent finches transfer some of their body burden of mercury to nestlings during feeding through secretion in the crop. These results suggest that, in mercury-exposed songbirds, pre-laying parental behaviors, combined with direct exposure of embryos to mercury, likely contribute to reduced reproductive success and should be considered in future studies. Further research is warranted in field settings, where parents are exposed to greater environmental challenges and subtle behavioral differences might have more serious consequences than were observed in captivity.
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Affiliation(s)
- Stephanie Y Chin
- Institute for Integrative Bird Behavior Studies, Department of Biology, College of William and Mary, Williamsburg, VA, 23185, USA
| | - William A Hopkins
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Daniel A Cristol
- Institute for Integrative Bird Behavior Studies, Department of Biology, College of William and Mary, Williamsburg, VA, 23185, USA.
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Albersheim-Carter J, Blubaum A, Ballagh IH, Missaghi K, Siuda ER, McMurray G, Bass AH, Dubuc R, Kelley DB, Schmidt MF, Wilson RJA, Gray PA. Testing the evolutionary conservation of vocal motoneurons in vertebrates. Respir Physiol Neurobiol 2015; 224:2-10. [PMID: 26160673 DOI: 10.1016/j.resp.2015.06.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [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: 02/23/2015] [Revised: 06/23/2015] [Accepted: 06/29/2015] [Indexed: 11/15/2022]
Abstract
Medullary motoneurons drive vocalization in many vertebrate lineages including fish, amphibians, birds, and mammals. The developmental history of vocal motoneuron populations in each of these lineages remains largely unknown. The highly conserved transcription factor Paired-like Homeobox 2b (Phox2b) is presumed to be expressed in all vertebrate hindbrain branchial motoneurons, including laryngeal motoneurons essential for vocalization in humans. We used immunohistochemistry and in situ hybridization to examine Phox2b protein and mRNA expression in caudal hindbrain and rostral spinal cord motoneuron populations in seven species across five chordate classes. Phox2b was present in motoneurons dedicated to sound production in mice and frogs (bullfrog, African clawed frog), but not those in bird (zebra finch) or bony fish (midshipman, channel catfish). Overall, the pattern of caudal medullary motoneuron Phox2b expression was conserved across vertebrates and similar to expression in sea lamprey. These observations suggest that motoneurons dedicated to sound production in vertebrates are not derived from a single developmentally or evolutionarily conserved progenitor pool.
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Affiliation(s)
- Jacob Albersheim-Carter
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Aleksandar Blubaum
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Irene H Ballagh
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA; Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Kianoush Missaghi
- Department of Exercise Science, Faculté des Sciences, Université du Québec à Montréal, Montréal, Québec H3C 3P8, Canada; Department of Neuroscience, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Edward R Siuda
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - George McMurray
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Andrew H Bass
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Réjean Dubuc
- Department of Exercise Science, Faculté des Sciences, Université du Québec à Montréal, Montréal, Québec H3C 3P8, Canada; Department of Neuroscience, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Darcy B Kelley
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Marc F Schmidt
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Richard J A Wilson
- Hotchkiss Brain Institute and ACH Research Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N4N1, Canada
| | - Paul A Gray
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Murray JR, Varian-Ramos CW, Welch ZS, Saha MS. Embryological staging of the Zebra Finch, Taeniopygia guttata. J Morphol 2013; 274:1090-110. [PMID: 23813920 PMCID: PMC4239009 DOI: 10.1002/jmor.20165] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 04/22/2013] [Accepted: 04/25/2013] [Indexed: 01/02/2023]
Abstract
Zebra Finches (Taeniopygia guttata) are the most commonly used laboratory songbird species, yet their embryological development has been poorly characterized. Most studies to date apply Hamburger and Hamilton stages derived from chicken development; however, significant differences in development between precocial and altricial species suggest that they may not be directly comparable. We provide the first detailed description of embryological development in the Zebra Finch under standard artificial incubation. These descriptions confirm that some of the features used to classify chicken embryos into stages are not applicable in an altricial bird such as the Zebra Finch. This staging protocol will help to standardize future studies of embryological development in the Zebra Finch.
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Affiliation(s)
- Jessica R Murray
- Biology Department, College of William and MaryP.O. Box 8795, Williamsburg, Virginia, 23187
| | - Claire W Varian-Ramos
- Biology Department, College of William and MaryP.O. Box 8795, Williamsburg, Virginia, 23187
| | - Zoe S Welch
- Biology Department, College of William and MaryP.O. Box 8795, Williamsburg, Virginia, 23187
| | - Margaret S Saha
- Biology Department, College of William and MaryP.O. Box 8795, Williamsburg, Virginia, 23187
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