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Title: Chronic dietary toxicity of methylmercury in the zebra finch, Poephila guttata

Abstract

Mercury (Hg) contamination of the environment through anthropogenic activity continues to be significant, and has resulted in the accumulation of elevated levels of Hg in invertebrates, fish and wildlife in certain Hg contaminated habitats. In addition, the availability of methylmercury (MeHg), a highly toxic and readily absorbable form of Hg, to the food chain is enhanced at low pH, an this has resulted in higher concentrations of Hg in various biota which inhabit environments sensitive to acid precipitation. The chronic dietary toxicity of MeHg has been investigated in a number of bird species including mallard ducks (Anas platyrhynchos, black ducks, pheasants, quail, and chickens. Except for a subchronic feeding study, the effects of MeHg on small passerines have not been studied. The present report describes the tissue accumulation and toxicity of MeHg in zebra finches (Poephila guttata) in response to chronic dietary exposure.

Authors:
Publication Date:
Research Org.:
Environment Canada, Ottawa, Ontario
OSTI Identifier:
5295595
Resource Type:
Journal Article
Resource Relation:
Journal Name: Bull. Environ. Contam. Toxicol.; (United States); Journal Volume: 40:1
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; METHYLMERCURY; CHRONIC EXPOSURE; TOXICITY; BIRDS; CANADA; DIET; INTESTINES; KIDNEYS; LIVER; ANIMALS; BODY; DIGESTIVE SYSTEM; GASTROINTESTINAL TRACT; GLANDS; MERCURY COMPOUNDS; NORTH AMERICA; ORGANIC COMPOUNDS; ORGANIC MERCURY COMPOUNDS; ORGANS; VERTEBRATES; 560300* - Chemicals Metabolism & Toxicology

Citation Formats

Scheuhammer, A.M.. Chronic dietary toxicity of methylmercury in the zebra finch, Poephila guttata. United States: N. p., 1988. Web. doi:10.1007/BF01689398.
Scheuhammer, A.M.. Chronic dietary toxicity of methylmercury in the zebra finch, Poephila guttata. United States. doi:10.1007/BF01689398.
Scheuhammer, A.M.. Fri . "Chronic dietary toxicity of methylmercury in the zebra finch, Poephila guttata". United States. doi:10.1007/BF01689398.
@article{osti_5295595,
title = {Chronic dietary toxicity of methylmercury in the zebra finch, Poephila guttata},
author = {Scheuhammer, A.M.},
abstractNote = {Mercury (Hg) contamination of the environment through anthropogenic activity continues to be significant, and has resulted in the accumulation of elevated levels of Hg in invertebrates, fish and wildlife in certain Hg contaminated habitats. In addition, the availability of methylmercury (MeHg), a highly toxic and readily absorbable form of Hg, to the food chain is enhanced at low pH, an this has resulted in higher concentrations of Hg in various biota which inhabit environments sensitive to acid precipitation. The chronic dietary toxicity of MeHg has been investigated in a number of bird species including mallard ducks (Anas platyrhynchos, black ducks, pheasants, quail, and chickens. Except for a subchronic feeding study, the effects of MeHg on small passerines have not been studied. The present report describes the tissue accumulation and toxicity of MeHg in zebra finches (Poephila guttata) in response to chronic dietary exposure.},
doi = {10.1007/BF01689398},
journal = {Bull. Environ. Contam. Toxicol.; (United States)},
number = ,
volume = 40:1,
place = {United States},
year = {Fri Jan 01 00:00:00 EST 1988},
month = {Fri Jan 01 00:00:00 EST 1988}
}
  • The authors measured the behavioral effects of methylmercury on 16 great egret chicks (Ardea albus) in a captive dosing experiment. Birds were randomly divided into a control group and groups that received 0.5 or 5 mg methylmercury chloride per kilogram of food at between 12 and 105 d of age. They recorded activity levels, maintenance behavior, and foraging efficiency and determined that mercury affected activity and maintenance behavior. Birds dosed with 5 mg/kg became severely ataxic and were euthanized by 12 weeks of age. The authors found that, during the postfledging period, there were no differences between low-dose and placebomore » birds in time required to capture live fish in pools or in efficiency of capture. They did find that low-dose birds were less likely to hunt fish. Their results suggest that, at the 0.5 mg/kg concentration in food, there are significant effects of methylmercury on activity, tendency to seek shade, and motivation to hunt prey.« less
  • The robust nucleus of the archistriatum (RA) is one of the forebrain nuclei that control song production in birds. In the zebra finch (Poephila guttata), this nucleus contains more and larger neurons in the male than in the female. A single injection of tritiated thymidine into the egg on the 6th or 7th day of incubation resulted in labeling of many RA neurons with tritium. The size of tritium-labeled neurons and the tissue volume containing them did not differ between the sexes at 15 days after hatching. In the adult brain, tritium-labeled neurons and the tissue volume containing them weremore » much larger in the male than in the female. Also, tritium-labeled RA neurons were large in females which received an implant of estrogen immediately after hatching. The gender differences in the neuron size and nuclear volume of the zebra finch RA are, therefore, due not to the replacement of old neurons by new ones during development but to the growth and atrophy of neurons born before hatching. Similarly, the masculinizing effects of estrogen on the female RA are due not to neuronal replacement but to the prevention of atrophy and promotion of growth in preexisting neurons.« less
  • Brain regions thought to be involved in the control of song in the zebra finch (Poephila guttata), were examined histochemically using the Karnovsky and Roots direct-coloring method for the detection of acetylcholinesterase (AChE) and the autoradiographic method for the localization of muscarinic cholinergic receptors following injection of tritiated quinuclidinyl benzilate (3H QNB). All presently identified vocal control nuclei in both males and females contain AChE. These nuclei include Area X, magnocellular nucleus of the anterior neostriatum (MAN), nucleus interface (NIF), caudal nucleus of the hyperstriatum ventrale (HVc), intercollicular nucleus (ICo), nucleus uva, robust nucleus of the archistriatum (RA), and tracheosyringealmore » portion of the hypoglossal nerve nucleus (nXIIts). All nuclei except Area X contain mostly AChE-synthesizing cell bodies. All of these nuclei contain some AChE in the neuropil, with particularly intense staining in Area X, the surrounding LPO, and the dorsomedial portion of ICo. In agreement with this description are very high concentrations of 3H QNB in both Area X and the dorsomedial ICo. HVc also appears specifically labeled. Evidence from these two histological technique suggests that efferent projections of most vocal control area may utilize acetylcholine, and that several of the vocal control nuclei may themselves receive muscarinic cholinergic projection. In Area X, there are sex differences of AChE neuropil staining. This evidence suggesting that sexually dimorphic projections to or within Area X are cholinergic or cholinoceptive.« less
  • We have localized nicotinic acetylcholine receptors in the zebra finch brain by using three 125I-labelled ligands: alpha bungarotoxin and two monoclonal antibodies to neuronal nicotinic receptors. Unfixed brains from intact adult male and female zebra finches were prepared for in vitro autoradiography. Low-resolution film autoradiograms and high-resolution emulsion autoradiograms were prepared for each of the three ligands. The major brain structures that bind all three of the ligands are hippocampus; hyperstriatum dorsalis; hyperstriatum ventralis; nucleus lentiformis mesencephali; nucleus pretectalis, some layers of the optic tectum; nucleus mesencephalicus lateralis; pars dorsalis; locus ceruleus; and all cranial motor nuclei except nucleus nervimore » hypoglossi. The major structures labelled only by (125I)-alpha bungarotoxin binding included hyperstriatum accessorium and the nuclei: preopticus medialis, medialis hypothalami posterioris, semilunaris, olivarius inferior, and the periventricular organ. Of the song control nuclei, nucleus magnocellularis of the anterior neostriatum; hyperstriatum ventralis, pars caudalis; nucleus intercollicularis; and nucleus hypoglossus were labelled. The binding patterns of the two antibodies were similar to one another but not identical. Both labelled nucleus spiriformis lateralis and nucleus geniculatus lateralis, pars ventralis especially heavily and also labelled the nucleus habenula medialis; nucleus subpretectalis; nucleus isthmi, pars magnocellularis; nucleus reticularis gigantocellularis; nucleus reticularis lateralis; nucleus tractus solitarii; nucleus vestibularis dorsolateralis; nucleus vestibularis lateralis; nucleus descendens nervi trigemini; and the deep cerebellar nuclei.« less
  • Expressions of the geneti and toxicity of mercurials at the molecular level include inhibition of DNA repair in algae, DNA strand breaks in a slime mould and in cultured mammalian cells, inhibition of a variety of mammalian enzymes including adenyl cyclase, and changes in macromolecular synthesis suggesting disturbances at the level of gene translation. The work reported here was undertaken to assess inhibition of capacity for DNA repair in leucocytes, and nuclear damage in bone marrow of cats after chronic exposure to low levels of dietary methylmercury.