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David A. Jett

Publications and source records attributed to David A. Jett.

9 recordsLinked to original sources
USGS1993

Down-regulation of muscarinic receptors and the m3 subtype in white-footed mice by dietary exposure to parathion

The effect of ad libitum dietary exposure (as occurs in the field) to parathion for 14 d was investigated on the muscarinic acetylcholine receptor (mAChR) in brains and submaxillary glands of adults of a field species, the white-footed mouse Peromyscus leucopus. Immunoprecipitation using subtype selective antibodies revealed that the relative ratios of the m1-m5 mAChR subtypes in Peromyscus brain were similar to those in rat brain. There was little variability in acetylcholinesterase (AChE) activity in control mice brains but large variability in 39 exposed mice, resulting from differences in food ingestion and parathion metabolism. Accordingly, data on radioligand binding to mAChRs in each mouse brain were correlated with brain AChE activity in the same mouse, and AChE inhibition served as a biomarker of exposure reflecting in situ paraoxon concentrations. Exposure to parathion for 14 d reduced maximal binding (Bmax) of [3H]quinuclidinyl benzilate ([3H]QNB), [3H]-N-methylscopolamine ([3H]NMS), and [3H]-4-diphenylacetoxy-N-methylpiperidine methiodide ([3H]-4-DAMP) by up to approximately 58% without affecting receptor affinities for these ligands. Maximal reduction in Bmax of [3H]QNB and [3H]-4-DAMP binding occurred in mice with highest AChE inhibition, while equivalent maximal reduction in Bmax of [3H]NMS occurred in mice with only approximately 10% AChE inhibition, without further change at higher parathion doses. This is believed to be due to the hydrophilicity of [3H]NMS, which limits its accessibility to internalized desensitized receptors. In submaxillary glands (mAChRs are predominantly m3 subtype), there were significant dose-dependent reductions in [3H]QNB binding and m3 mRNA levels in exposed mice, revealed by Northern blot analyses. The reduction in m3 receptors is suggested to result mostly from reduced synthesis at the transcription level, rather than from translational or posttranslational events. The data suggest that down-regulation of mAChRs occurs after dietary exposure for 14 d to sublethal concentrations of parathion in a field rodent species, and that significant though incomplete recovery in AChE and mAChRs occurs in 7 d following termination of exposure.

Journal of Toxicology and Environmental Health↗
USGS1993

A receptor binding assay applied to monitoring the neurotoxicity of parathion to Peromyscus after oral exposure

Many naturally occurring toxins, as well as pesticides, metals, and other compounds that occur in our environment from anthropogenic activities, stimulate or antagonize neuro-receptors to produce acute and/or chronic toxicities. Recent advances in laboratory instrumentation and the availability of a variety of radiolabeled ligands and type-specific drugs for numerous receptors make it possible to easily screen large numbers of samples and detect changes in sensitivity and density of receptor types and subtypes. A receptor binding assay for examining the chronic dietary toxicity of parathion will be used as a model to describe the methodology.

Book chapter↗
USGS1989

Kirtland's warblers on the nesting grounds during the post- breeding period

Information indicates that a substantial number of breeding birds remain in Michigan through September, and a few individuals probably remain into early October. Migration apparently consists of two waves of migrants: an early departure (mid-August to early September); and late departure (late September). Based on our findings, we recommend that major Kirtland's warbler areas be kept closed into mid-September.

The Wilson Bulletin↗
USGS1989

Additional records of birds from Cat Island, Bahamas

During 11-15 March 1986, we visited Cat Island in the Bahamas. Here we report on 27 species of birds whose status on Cat Island is poorly known, including eight for which no pervious records exist.

The Wilson Bulletin↗
USGS1987

A field comparison of nested grid and trapping web density estimators

The usefulness of capture-recapture estimators in any field study will depend largely on underlying model assumptions and on how closely these assumptions approximate the actual field situation. Evaluation of estimator performance under real-world field conditions is often a difficult matter, although several approaches are possible. Perhaps the best approach involves use of the estimation method on a population with known parameters.

Journal of Mammalogy↗
USGS1986

Cholinesterase inhibition in meadow voles (Microtus Pennsylvanicus) following field applications of orthene®

Brain acetylcholinesterase activity in field-caught meadow voles ( Microtus pennsylvanicus ) was depressed after a field-spray of Orthene® (acephate: acetylphosphoramidothioic acid O,S -dimethyl ester) by as much as 32% in 1982 and 38% in 1983. Short-term recovery was demonstrated and occurred in a time-dependent fashion in 1982. Plasma Cholinesterase levels were more variable but also were depressed. Residues were detected in vegetation samples and in the gastrointestinal tracts of exposed voles. Residues in vegetation were diluted or absent 7 to 8 d following the treatment.

Environmental Toxicology and Chemistry↗
USGS1986

Effect of Orthene on an unconfined population of the meadow vole (Microtus pennsylvanicus)

The possible impact on Microtus pennsylvanicus of ground applications of Orthene ® insecticide was investigated in old-field habitats in northern Maryland during 1982 and 1983. The treatment grids in 1982 and 1983 were sprayed at 0.62 and 0.82 kg active ingredient/ha, respectively. A capture–recapture design robust to unequal capture probabilities was utilized to estimate population size, survival, and recruitment. Data on reproductive activity and relative weight change were also collected to investigate the effect of the insecticide treatment. There were no significant differences in population size or recruitment between control and treatment grids which could be directly related to the treatment. Survival rate was significantly lower on the treatment grid than on the control grid after spraying in 1983; however, survival rate was higher on the treatment grid after spraying in 1982. Significantly fewer pregnant adults were found on the treatment grid after spraying in 1982, whereas the proportions of voles lactating or with perforate vaginas or open pubic symphyses were slightly higher or remained unchanged during this period. Relative weight change was not affected by the treatment. Results do not indicate any pattern of inhibitory effects from the insecticide treatment. Field application of Orthene ® did not have an adverse effect on this Microtus population.

Canadian Journal of Zoology↗
USGS1983

Effects of the insecticide, orthene, on unconfined populations of the meadow vole (Microtus pennsylvanicus). I. Capture/recapture procedures; II. Residues and cholinesterase inhibition

In 1982 and 1983. the population demography of M. pennsylvanicus was not altered significantly by single or double applications of Orthene. Although inconsistencies in population size, survival, and recruitment were not explained by differences between control and experimental grids in breeding, emigration, interspecific competition, or pesticide-induced mortality, there may have been fundamental microhabitat differences between grids in both years, and this is supported by prespray data. Slight differences between grids may also reflect the random error associated with the models used to estimate parameters. No evidence was found to indicate an effect on relative weight change or average distances moved. The level of brain AChE in 1982 during sequential days after spraying was significantly lower than control levels. However, this inhibition was not enough to cause direct mortality. Recovery of brain AChe was gradual, probably reflecting continual re-exposure through the diet. Acephate and methamidophos residues were present in the vegetation collected from sprayed areas immediately following treatment, but were reduced or absent after 8 days. AChE inhibition in 1982 and 1983 extended beyond the disappearance of residues in the vegetation. Residues were only present in the G.l. tracts of voles collected immediately following treatment due to rapid metabolism and excretion. Levels in the vegetation and G.l. tracts in 1982 and 1983 were well below the rat oral LD50 of acephate. It is concluded that Orthene applied at recommended levels, in a single or double treatment, should not affect unconfined populations of M. pennsylvanicus in Maryland old-field habitats. Furthermore, this study confirms this method as a sensitive means to determine the overall impact of insecticides on wildlife populations. However, caution must be exercised to insure that all control and experimental areas are closely scrutinized for habitat differences.

Book↗