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PubMed2005

Rodents as receptor species at a tritium disposal site.

New methods are being employed on the Department of Energy's Savannah River Site to deal with the disposal of tritium, including the irrigation of a hardwood/pine forest with tritiated water from an intercepted contaminant plume to reduce concentrations of tritium outcropping into Fourmile Branch, a tributary of the Savannah River. The use of this system has proven to be an effective means of tritium disposal. To evaluate the impact of this activity on terrestrial biota, rodent species were captured on the tritium disposal site and a control site during two trapping seasons in order to assess tritium exposure resulting from the forest irrigation. Control site mice had background levels of tritium, 0.02 Bq/mL, with disposal site mice having significantly higher tritium concentrations, mean=34.86 Bq/mL. Whole body tritium concentrations of the mice captured at the disposal site were positively correlated with tritium application and negatively correlated with precipitation at the site.

Animals↗
PubMed2004

Behavior-related alterations of striatal neurochemistry in a mouse model of stereotyped movement disorder.

Motor stereotypy is a common component of several developmental, genetic, and neuropsychiatric disorders. In animals, these behaviors can be induced or attenuated via pharmacological manipulation of specific neural loci comprising cortico basal ganglia-cortical feedback circuits, including the striatum. The present study employed the deer mouse model of spontaneous and persistent stereotypy to assess the involvement of several endogenous neurotransmitters and neuromodulators in mediating the expression of the stereotypic behaviors (i.e., repetitive hindlimb jumping) exhibited by these mice. This was accomplished by employing a microdialysis sampling system coupled on-line to capillary electrophoresis with laser-induced fluorescence (CE-LIF) detection apparatus. Given the 13-s temporal resolution for analyte measurement afforded by this system, discrete behavior-related alterations in striatal neurochemical concentrations were detected. Rearing behavior was found to be associated with significant and selective elevations of striatal glutamate (Glu) and aspartate (Asp) concentrations. Moreover, rearing was found to most frequently precede repetitive jumping. The results also indicated that alterations in striatal serine (Ser) concentrations were involved in the modulation of locomotor activity. The present findings support a role of the striatal glutamatergic system in the mediation of spontaneous stereotypic behavior and suggest a potential neuronal mechanism by which transition to stereotypy occurs in these mice. Moreover, the present findings demonstrate the usefulness of the microdialysis system employed in studying the neurochemical substrates of rapidly transitioning behavior.

Amino Acids↗
PubMed2003

Environmental enrichment: effects on stereotyped behavior and neurotrophin levels.

The present study evaluated whether environmental enrichment-related effects on the development of stereotyped behavior in deer mice were associated with alterations in neurotrophin levels. Deer mice were reared in enriched or standard cage conditions for 60 days. The mice were then tested in automated photocell detectors and classified as either stereotypic or nonstereotypic. This testing paradigm yielded four behaviorally distinct groups: enriched stereotypic, enriched nonstereotypic, standard cage stereotypic, and standard cage nonstereotypic. The motor cortex, striatum, and hippocampus were dissected, and the levels of brain-derived neurotrophin factor (BDNF) and nerve growth factor (NGF) in each brain region were analyzed using Promega ELISA kits. There were no differences in either NGF or BDNF in either the motor cortex or the hippocampus. In the striatum, the enriched nonstereotypic mice exhibited significantly more BDNF than the enriched stereotypic, the standard cage nonstereotypic, or the standard cage stereotypic mice. There were no differences in NGF in the striatum. These results provide evidence that the enrichment-related prevention of stereotyped behavior in deer mice is associated with increased BDNF in the striatum.

Animals↗
PubMed2004

Effects of intrastriatal administration of selective dopaminergic ligands on spontaneous stereotypy in mice.

Abnormal repetitive behaviors are often associated with specific developmental, genetic, and neuropsychiatric disorders. Repetitive motor behaviors, often referred to as stereotypies, have been studied extensively as they can be readily induced by certain drugs (e.g., amphetamine). Recent work has shown, however, that such drug-induced models of stereotypy may not accurately reflect the neurobiological perturbations responsible for the spontaneous manifestation of these behaviors. The present study employed the deer mouse model of spontaneous and persistent stereotypy to evaluate the capacity of several selective dopaminergic agonists (apomorphine, SKF81297, and quinpirole) to exacerbate levels of spontaneously emitted stereotypic topographies when administered intrastriatally. Additionally, the effects of intrastriatal administration of the D(2)R antagonist raclopride on the expression of spontaneous stereotypic jumping were evaluated. No induction or exacerbation of stereotypy was observed following administration of the selective D(1)- or D(2)- receptor agonists, and the mixed agonist apomorphine induced hyperlocomotion and excessive grooming but failed to exacerbate spontaneous stereotypy. Thus, a dissociation was observed between spontaneously emitted and drug-induced stereotypy, suggesting significant limitations to the use of dopamine agonist-induced stereotypy as a model of clinical stereotyped movement disorder. Furthermore, an unexpected and statistically significant (P<.05) potentiation of locomotor activity was observed following intrastriatal raclopride administration, suggesting major alterations to the modulatory characteristics of the striatal dopaminergic system in these spontaneously stereotypic animals.

Animals↗
PubMed2005

Comparative genomics of the sperm mitochondria-associated cysteine-rich protein gene.

The sperm mitochondrial cysteine-rich protein (SMCP) is a rapidly evolving cysteine- and proline-rich protein that is localized in the mitochondrial capsule and enhances sperm motility. The sequences of the SMCP protein, gene, and mRNA in a variety of mammals have been compared to understand their evolution and regulation. SMCP can now be reliably identified by its tripartite structure including a short amino-terminal segment; a central segment containing short tandem repeats rich in cysteine, proline, glutamine, and lysine; and a C-terminal segment containing no repeats, few cysteines, and a C-terminal lysine. The SMCP gene is located in the epidermal differentiation complex (EDC), a large gene cluster that functions in forming epithelial barriers. Similarities in chromosomal location, molecular function, intron-exon structure, and protein organization argue that SMCP originated from an EDC gene and acquired spermatogenic cell-specific transcriptional and translational regulation and a novel cellular function in sperm motility. The SMCP 5' UTR and 3' UTR contain conserved elements and uORFs that may function in cytoplasmic regulation of gene expression, and the levels of SMCP mRNA in human are much lower than in other mammals, a feature of male-biased expression. The evolution of SMCP has been accompanied by changes in the sequence, number, and length of repeat units, including three alleles in dogs. The major proteins associated with the mitochondrial capsule, SMCP and phospholipid hydroperoxide glutathione peroxidase, provide outstanding examples of changes in cellular function driven by selective pressures on sperm motility, an important determinant of male reproductive success.

3' Untranslated Regions↗
PubMed2002

Environmental enrichment: effects on stereotyped behavior and regional neuronal metabolic activity.

The present study evaluated whether environmental enrichment-related effects on the development of stereotyped behavior in deer mice were associated with alterations in neuronal metabolic activity. Deer mice were reared under either enriched or standard housing conditions for 60 days following weaning. All mice were then placed in automated photocell detectors and classified as either stereotypic or non-stereotypic. Neuronal metabolic activity was then assessed using cytochrome oxidase (CO) histochemistry. The results demonstrated that environmental enrichment significantly increased neuronal metabolic activity in the motor cortex. Furthermore, non-stereotypic mice exhibited significantly more CO activity than stereotypic mice in the cortex, striatum, nucleus accumbens, thalamus, hippocampus and amygdala. This latter effect was due to the enriched mice as evidenced by a significant interaction between housing condition and behavioral status in the cortex, striatum, nucleus accumbens, thalamus and hippocampus. Thus, the observed increase in CO activity reflected increased neuronal metabolic activity in non-stereotypic enriched mice relative to stereotypic enriched mice. These results suggest that, in a developmental model of spontaneous stereotypy, the enrichment-related prevention of stereotyped behavior is associated with increased CO activity.

Animals↗
PubMed1999

A rodent model of spontaneous stereotypy: initial characterization of developmental, environmental, and neurobiological factors.

Stereotypies are patterns of motor behavior that are repetitive, excessive, topographically invariant, and that lack any obvious function or purpose. In humans, stereotyped behaviors are associated with psychiatric, neurological, and developmental disorders. In animals, stereotypy has been frequently associated with adverse environmental circumstances and often related to alterations in striatal dopamine. To assess the development of stereotyped behaviors and to test the hypothesis that these behaviors are associated with environmental restriction, deer mice were housed in either standard laboratory cages or larger, enriched cages, and the development of stereotypy was followed from weaning over a 17-week period. Standard-caged deer mice engaged in stereotyped behaviors at a higher rate and developed these behaviors more quickly when compared to animals in enriched caging. Additionally, enriched caging was associated with higher rates of patterned running, whereas jumping and backward somersaulting were typically observed in standard cages. In addition, there was a significant effect of litter, but no effect of sex or cage, on the time to develop stereotypy. No differences were found in the density of either striatal D1 or D2 dopamine receptors or the concentration of striatal dopamine or its metabolites as a function of rearing condition or as a function of whether the animals developed stereotypy. These results characterize the development of stereotypies in this species, demonstrate the importance of environmental conditions in the genesis of stereotypy, and suggest that alterations in striatal dopamine content or dopamine receptor density do not account for the expression of stereotyped behaviors in this model.

Aging↗
PubMed2003

Selective blockade of spontaneous motor stereotypy via intrastriatal pharmacological manipulation.

Abnormal repetitive behavior, including stereotypy, is often observed in conjunction with developmental, neuropsychiatric, and genetic disorders. The present work employed the deer mouse model of spontaneous and persistent stereotypy to identify basal ganglia involvement in the mediation of these abnormal behaviors. To evaluate the hypothesis that stereotypy is expressed in these mice due to alterations in the activity of cortico-basal ganglia motor circuits, intrastriatal pharmacological manipulations aimed at attenuating the spontaneously emitted stereotypy were performed. Bilateral striatal infusion of the NMDA or dopamine D(1) receptor antagonists MK-801 or SCH23390, respectively, produced a substantial reduction in levels of stereotypic jumping without inhibiting nonstereotypic motor behavior. These findings support the hypothesis that environmentally related stereotypy is expressed as a consequence of elevated feedback activity occurring along motor circuits of the basal ganglia.

Animals↗
PubMed2003

Traveling waves of infection in the hantavirus epidemics.

Traveling waves are analyzed in a model of the hantavirus infection in deer mice. The existence of two kinds of wave phenomena is predicted. An environmental parameter governs a transition between two regimes of propagation. In one of them the front of infection lags behind at a constant rate. In the other, fronts of susceptible and infected mice travel at the same speed, separated by a constant delay. The dependence of the delay on system parameters is analyzed numerically and through a piecewise linearization.

Animals↗
PubMed1986

Evolution of a focus of Lyme disease.

Epidemiological investigations were initiated in 1984 when significant Lyme disease activity was observed within a 5-km radius of an area previously used as a non-endemic control site for Lyme disease research in New Jersey. Through 1983, collections of Ixodes dammini from vegetation and feral rodents were infrequent and no human cases were identified within a 16-km radius of the control site. In 1984, 4 human cases and 3 serologically reactive canines (greater than or equal to 1:512) were recognized within the area and adult I. dammini populations were over 3-fold greater than those at our primary study location where Lyme disease has been endemic since 1981. Using darkfield microscopy, 53.4% of adult I. dammini were infected with Borrelia burgdorferi as compared to 50.0% of adults collected during the same period at the known endemic study site. These data indicate that a focus of Lyme disease has recently become established at the previously non-endemic control site and that the establishment of new foci may occur more rapidly than once thought.

Animals↗
PubMed2003

Rodent sperm analysis in field-based ecological risk assessment: pilot study at Ravenna army ammunition plant, Ravenna, Ohio.

Ecological risk assessment (ERA) guidance recommends that field-truthing efforts proceed when modeled hazard quotients (HQs) suggest that toxicological effects are occurring to site receptors. To date, no field methods have been proposed by the regulatory community that can lead to definitive determinations of acceptable or unacceptable risk for birds and mammals, the two terrestrial classes of receptors that are commonly assessed using the HQ method. This paper describes rodent sperm analysis (RSA) as a viable method to be applied in the field at sites with historical contamination. RSA is capable of detecting biological differences that bear on reproduction, a highly regarded toxicological endpoint of concern in USEPA Superfund-type ERAs. The results of RSA's first application at a study site are reported and discussed. The paper also provides the rationale for RSA's efficacy in the context of Superfund and other environmental cleanup programs, where limited time and money are available to determine and evaluate the field condition.

Animals↗
PubMedDate not supplied

Design of oligonucleotide arrays to detect point mutations: molecular typing of antibiotic resistant strains of Neisseria gonorrhoeae and hantavirus infected deer mice.

Microarrays are promising tools for use in molecular diagnostics due to their ability to perform a multitude of tests simultaneously. In the case of genotyping many such tests will require discrimination of sequence at the single nucleotide level. A number of challenges exist including binding of optimal quantities of probe to the chip surface, the use of uniform hybridization conditions across the chip and the generation of labeled target. We investigated two model systems to test out the efficacy and ease with which probes can be designed for this purpose. In the first of these we designed primers to identify five mutations found in two genes from N. gonohorroeae, gyrA and parC that have been implicated in ciprofloxacin resistance. In the second system we used a similar strategy to identify four mutations in AT rich mitochondrial DNA from deer mice. These mutations are associated with deer mice subspecies that originate from different geographical regions of Canada and harbor different hantavirus strains. In every case we were able to design probes that could discriminate mutations in the target sequences under uniform hybridization conditions, even when targets were fairly long in length, up to 400 bp. Our results suggest that microarray analysis of point mutations might be very useful for automated identification and characterization of pathogens and their hosts.

Animals↗
PubMed1996

Isozyme multiplicity with anomalous dimer patterns in a class III alcohol dehydrogenase. Effects on the activity and quaternary structure of residue exchanges at "nonfunctional" sites in a native protein.

The isozymes of class III alcohol dehydrogenase/glutathione-dependent formaldehyde dehydrogenase from cod were characterized. They exhibited three unexpected properties of general interest. First, these dimeric isozymes, derived from two types of subunit (h and l, for high- and low-activity forms), were recovered from liver preparations in only the homodimeric ll and heterodimeric hl combinations. Dissociation and reassociation of the isolated hl form in vitro also resulted in lower yields of the hh than the ll homodimer, although class III subunits are usually freely associable over wide borders of divergence (human and Drosophila). The h and l primary structures show that both chain types are characteristic of class III enzymes, without large amino acid replacements at positions of known subunit interactions. Hence, the hh dimer partial restriction indicates nontraditional alterations at h-subunit interfaces. The structure provides a possible explanation, in the form of h-chain modifications that may influence the anchoring of a loop at positions of two potentially deamidative beta-aspartyl shifts at distant Asn-Gly structures. Second the ll and hl forms differ in enzymatic properties, having 5-fold different K(m) values for NAD+ at pH 8, different K(m) values for S-(hydroxymethyl)glutathione (10 versus 150 microM), and different specific activities (4.5 versus 41 units/mg), with ll resembling and hl deviating from human and other class III alcohol dehydrogenases. However, functional residues lining substrate and coenzyme pockets in the known conformations of homologous forms are largely identical in the two isozymes [only minor conservative exchanges of Val/Leu116, Val/Leu203, Ile/Val224, and Ile/Val269 (numbering system of the human class I enzyme)], again indicating effects from distantly positioned h-chain replacements. Third, the two isozymes differ a surprising amount in amino acid sequence (18%, the same as the piscine/ human difference), reflecting a remarkably old isozyme duplication or, more probably, discordant accumulation of residue exchanges with greater speed of evolution for one of the subunits (h chain) than is typical for the slowly evolving class III alcohol dehydrogenase.

Aldehyde Oxidoreductases↗
PubMed2002

Noncryogenic preservation of mammalian tissues for DNA extraction: an assessment of storage methods.

Reliable field methods for the storage of tissues to be used for DNA extraction and amplification are critical to many studies employing molecular techniques. Protection from DNA degradation was compared among three commonly used methods of noncryogenic storage of tissues over a time scale of 2 years. All three methods prevented DNA degradation during storage for at least 6 months. DMSO (dimethyl sulfoxide)-salt solution provided the best protection from DNA degradation of tissues stored for up to 2 years. High molecular weight DNA was recovered from lysis buffer in which tissue was stored for 2 years, however, moderate amounts of degraded DNA was also present. High molecular weight DNA was recovered from tissues stored in ethanol for 2 years, however the yield was relatively small compared to the other two noncryogenic storage techniques. Much of the DNA degradation in ethanol preserved tissues appeared to occur during the extraction procedure and can be reduced by soaking the tissue in lysis buffer for a few hours prior to beginning the extraction. The yield of PCR products was greatest from DNA extracted from DMSO-salt solution preserved tissues, whereas DNA from tissues stored in either lysis buffer or ethanol produced lower yields.

Animals↗