Availability and distribution of potential black bear den trees in Cherokee National Forest

This thesis examines the availability and distribution of potential black bear den trees in Cherokee National Forest (CNF). Potential den trees are defined as any tree greater than 66 cm diameter at breast height (DBH). Forty potential den trees were located on 44 transects. These transects were selected randomly from United States Forest Service stand inventories. Sampling of these transects resulted in a total of 61 ha sampled in the Hiwassee, Ocoee, and Tellico Ranger Districts of the CNF. Each stand was categorized by age class and cover type. The age classes were 0-10, 10-30, 30-60, and 60+ years. Cover types were Pine, Pine- Hardwood, Hardwood-Pine, and Hardwood. Cover type was shown to be helpful in predicting the availability of potential den trees. Significantly more (p=0.0003) potential den trees were located in hardwood stands than in the other cover types. Age class did not prove to be a useful predictor of potential den tree availability in this study. There does not appear to be an absolute shortage of potential den trees in CNF. However, due to past logging practices, many of these trees are clumped in distribution. That is, many times several such trees are found in close proximity. Ground den opportunities in CNF appear to be abundant. In terms of sheer numbers, wilderness areas and designated old-growth hardwood areas should provide ample denning opportunities for black bears. However, it would be wise to limit access to potential maternity areas forest wide. This would help ensure the successful reproduction of black bears in the southern Appalachians

Plane-wave methods for modelling photonic crystal fibre

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Negative pretrial publicity and juror verdicts: testing the demand characteristics hypothesis

Two studies were conducted to investigate if demand characteristics could explain the relation between increased guilty verdicts and negative pretrial publicity. The purpose of study 1 is to show that when we keep demand characteristics constant between levels of pretrial publicity, but vary the degree of pretrial publicity, guilt judgments differ between the control and negative pretrial publicity groups, but the two levels of negative pretrial publicity do not differ. A total of 172 university undergraduates participated in this study and were randomly assigned to one of three groups. Participants read a mock trial transcript, along with mock newspaper articles, and rendered verdicts, beliefs about study intent and completed Gudjonsson’s Compliance Scale. The results indicated, contrary to what was hypothesized, guilt judgments did not vary according to a demand characteristics model. That is, the two NPTP groups did not differ significantly from the control group on guilt judgments. The purpose of study 2 was to show that if we keep negative pretrial publicity constant but vary the demand characteristics, guilt judgments will vary across conditions. A total of 192 university undergraduate students were randomly assigned to one of four conditions (control, NPTP, DC Guilty, DC not guilty). Participants read the identical trial transcript as study 1, as well as the weak NPTP condition mock newspaper articles in study 1 (for all conditions but control). In addition, participants completed Gudjonsson’s measure of compliance and rendered verdicts along with study intent ratings. The results again revealed findings inconsistent with a demand characteristics model. Here, none of the four groups differed significantly from one anothe

Analysis of six candidate genes as potential modifiers of disease expression in canine XLPRA1, a model for human X-linked retinitis pigmentosa 3

Purpose: Canine X-linked progressive retinal atrophy (XLPRA) is caused by mutations in RPGR exon ORF15, which is also a mutation hotspot in human X-linked retinitis pigmentosa 3 (RP3). The XLPRA1 form of disease has shown extensive phenotypic variability in a colony of dogs that all inherited the same mutant X-chromosome. This variability in onset and severity makes XLPRA1 a valuable model to use to identify genes influencing photoreceptors degeneration in dog and to elucidate molecular mechanisms underlying RP in its human homolog. In this study, RPGRIP1, RANBP2, NPM1, PDE6D, NPHP5, and ABCA4 genes were selected on the basis of interaction with RPGR or RPGRIP1 or their implication in related retinal diseases, and were investigated as candidate genetic modifiers of XLPRA1. Methods: A pedigree derived from an affected male dog outcrossed to unrelated normal mix bred or purebred females was used. Morphologic examination revealed phenotypic variability in the affected dogs characterized as mild, moderate, or severe. Single nucleotide polymorphisms (SNPs) and indel-containing markers spanning the entire genes were designed, based on the canine sequence and the Broad Institute SNP library, and genotyped on the pedigree. For each candidate gene, haplotypes were identified and their frequencies in severely and moderately affected dogs were compared to detect a putative correlation between a gene-specific haplotype(s), and severity level of the disease. Primers were derived from expressed sequence tags (ESTs) and predicted transcripts to assess the relative retinal expression of the six genes of interest in normal and affected retinas of different ages. Results: Four to seven haplotypes per gene were identified. None of the haplotypes of RPGRIP1, NPM1, PDE6D, NPHP5, RANBP2, and ABCA4 were found to co-segregate with the moderate or severe phenotype. No significant difference in the retinal expression levels of the candidate genes was observed between normal and affected dogs. Conclusions: The haplotype distribution of RPGRIP1, NPM1, PDE6D, NPHP5, RANBP2, and ABCA4 suggests these genes are not modifiers of the disease phenotype observed in the XLPRA1 pedigree. The RPGRORF15 stop mutation does not affect the retinal expression of these genes at the mRNA level in the pre-degenerate stage of disease, but no conclusions can be made at this time about changes that may occur at the protein level

Congenital Stationary Night Blindness in the Dog: Common Mutation in the RPE65 Gene Indicates Founder Effect

Purpose: To clone and characterize the canine RPE65 cDNA from normal dog, examine for mutations, and establish if the mutation identified in Swedish briard dogs with retinal dystrophy is present in dogs of the same breed that originated from the United States and other countries, and are affected with congenital stationary night blindness. Methods: Fifteen briard dogs were studied, of which 10 were affected with csnb, and five were clinically normal. In addition, we tested samples from four Swedish dogs, and samples from a briard affected with progressive retinal atrophy. RPE65 cDNA was cloned a from retinal cDNA library by PCR, and from canine retina by RT-PCR. ERG and morphology were used to characterize csnb. Results: The normal RPE65 cDNA spans 1724 nucleotides (GenBank accession number AF084537), and includes 1602 nucleotides of coding sequence; the deduced amino acid sequence shares 98%, 97%, and 93% identity with homologous human, bovine, and rat sequences, respectively. A homozygous four nucleotide (AAGA) deletion, representing nucleotides 487-490 of wildtype RPE65 sequence, was found only in csnb and retinal dystrophy affected dogs; heterozygous animals had normal and mutant alleles. The mutation produces a frameshift, causing a deduced mistranslation with a premature stop codon. The mutation causes retinal dysfunction and RPE accumulation of lipid vacuoles. Conclusions: Identification of the same mutation in csnb and retinal dystrophy confirms the molecular identity of the two disorders. A common mutation in dogs derived from different countries suggests a founder effect causing the propagation of a common mutant allele in the population at risk

Steroids Do Not Prevent Photoreceptor Degeneration in the Light-Exposed T4R Rhodopsin Mutant Dog Retina Irrespective of AP-1 Inhibition

PURPOSE. AP-1 has been proposed as a key intermediate linking exposure to light and photoreceptor cell death in rodent light-damage models. Inhibition of AP-1 associated with steroid administration also prevents light damage. In this study the role of steroids in inhibiting AP-1 activation and/or in preventing photoreceptor degeneration was examined in the rhodopsin mutant dog model. METHODS. The dogs were dark adapted overnight, eyes dilated with mydriatics; the right eye was light occluded and the fundus of the left eye photographed (∼15–17 overlapping frames) with a fundus camera. For biochemical studies, the dogs remained in the dark for 1 to 3 hours after exposure. Twenty-four hours before exposure to light, some dogs were treated with systemic dexamethasone or intravitreal/subconjunctival triamcinolone. AP-1 DNA-binding activity was determined by electrophoresis mobility shift assay (EMSA) and phosphorylation of c-Fos and activation of ERK1/2 were determined by immunoblot analyses. The eyes were collected 1 hour and 2 weeks after exposure to light, for histopathology and immunocytochemistry. RESULTS. Inhibition of AP-1 activation, and phosphorylation of ERK1/2 and c-Fos were found after dexamethasone treatment in light-exposed T4R RHO mutant dog retinas. In contrast, increased AP-1 activity and phosphorylation of c-Fos and ERK1/2 were found in triamcinolone-treated mutant retinas. Similar extensive rod degeneration was found after exposure to light with or without treatment, and areas with surviving photoreceptor nuclei consisted primarily of cones. Only with systemic dexamethasone did the RPE cell layer remain. CONCLUSIONS. Intraocular or systemic steroids fail to prevent light-induced photoreceptor degeneration in the T4R RHO dog retina. Finding that systemic dexamethasone prevents AP-1 activation, yet does not prevent retinal light damage, further supports the hypothesis that AP-1 is not the critical player in the cell-death signal that occurs in rods

Different current intensities of anodal transcranial direct current stimulation do not differentially modulate motor cortex plasticity

Transcranial direct current stimulation (tDCS) is a noninvasive technique that modulates the excitability of neurons within the motor cortex (M1). Although the aftereffects of anodal tDCS on modulating cortical excitability have been described, there is limited data describing the outcomes of different tDCS intensities on intracortical circuits. To further elucidate the mechanisms underlying the aftereffects of M1 excitability following anodal tDCS, we used transcranial magnetic stimulation (TMS) to examine the effect of different intensities on cortical excitability and short-interval intracortical inhibition (SICI). Using a randomized, counterbalanced, crossover design, with a one-week wash-out period, 14 participants (6 females and 8 males, 22–45 years) were exposed to 10 minutes of anodal tDCS at 0.8, 1.0, and 1.2 mA. TMS was used to measure M1 excitability and SICI of the contralateral wrist extensor muscle at baseline, immediately after and 15 and 30 minutes following cessation of anodal tDCS. Cortical excitability increased, whilst SICI was reduced at all time points following anodal tDCS. Interestingly, there were no differences between the three intensities of anodal tDCS on modulating cortical excitability or SICI. These results suggest that the aftereffect of anodal tDCS on facilitating cortical excitability is due to the modulation of synaptic mechanisms associated with long-term potentiation and is not influenced by different tDCS intensities