The olfactory system is a great model to ask questions related to neuronal regeneration, axon guidance and synapse formation. Processing of smell begins in the olfactory epithelium where sensory neurons are present and the olfactory bulb is the first stop in processing odor information in the central nervous system. While the olfactory bulb has neurons that regenerate as well, we are interested in the regeneration that occurs in the olfactory epithelium after being injured because it possesses a source of neural stem cells – something unique to the rest of the body. Earlier studies have proven that the introduction of methimazole will effectively damage the olfactory sensory neurons while keeping the neural stem cells intact. By using a fate mapping technique involving Cre-ERT2 mice, we are able to track the regeneration of these sensory neurons after a methimazole induced injury. Using immunohistochemistry in combination with ImageJ software analysis, we are able to pinpoint the colocalization of markers of new olfactory sensory neurons (green fluorescent protein (GFP)) with markers of neuron maturation (olfactory marker protein (OMP)) and synapse formation (tyrosine hydroxylase (TH) and synaptophysin). Analysis of maturation was done in the olfactory epithelium by studying the colocalization of the protein OMP and GFP. Data shows that after regeneration, neurons coexpress both markers 11 days after lesion. In the olfactory bulb, we characterized the recovery of synaptic markers TH and synaptophysin after axons reached the olfactory bulb, where olfactory sensory neuron axons make synaptic contacts with dendrites of projection neurons. Overall, these data are the first one to establish a timeline for axonal regeneration and synapse formation after injury in the olfactory system.

The current study utilized a multiple baseline design to teach olfactory discrimination skills to adolescent participants with autism spectrum disorders. Relational abilities among smells and causal relations were initially probed and an intervention was implemented via training and reversal testing probes using frames of distinction between stimulus depicting clean clothing (A) and worn clothing (B), causal framing to relate those odors with specific actions stimulus depicting clean clothing (A) with wearing or hanging the clothing (C) and stimulus depicting worn clothing (B) and placing the clothing in the laundry or hamper (D). Finally, these skills were tested in an applied setting when comparing clothing items that may or may not need to be laundered through the demonstrate of transformation of stimulus function in a novel setting by testing relations between clean clothing (Y) and wearing or hanging the clothing (C) and previously worn clothing( Z) and putting them in the laundry or hamper (D). The intervention was effective at establishing these relational responses for all 4 participants throughout each phase leading to the application of these responses in an applied setting with 80%-100%. Limitations and future application are discussed involving the use of cross modal stimuli in when teaching relations and broader implications of the science.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第17903号 / 農博第2026号 / 新制||農||1018(附属図書館) / 学位論文||H25||N4799(農学部図書室) / 30723 / 京都大学大学院農学研究科応用生物科学専攻 / (主査)教授 佐久間 正幸, 教授 松浦 健二, 教授 天野 洋 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

The evolution of genes and genomes has attracted great interest. The research presented here is an examination of genomes at three distinct levels, protein evolution, gene family evolution, and TE content regulation. First at a genetic level, I conducted an analysis of the salivary androgen-binding proteins (ABPs). I focused on comparing patterns of molecular evolution between the Abpa gene expressed in the submaxillary glands of species of New World and Old World muroids and found that in both sets of rodents, the Abpa gene expressed in the submaxillary glands appear to be evolving under sexual selection, suggesting ABP might play a similar biological role in both systems. Thus, ABP could be involved with mate recognition and species isolation in New World as well as Old World muroids. Second I examined the largest gene family in vertebrate olfactory receptors (ORs) among birds and reptiles. I found that the number of intact OR genes in sauropsid genomes analyzed ranged over an order of magnitude, from 108 in the lizard to over 1000 in turtles. My results suggest that different sauropsid lineages have highly divergent OR repertoire compositions. These differences suggest that varying rates of gene birth and death, together with selection related to diverse natural histories, have shaped the unique OR repertoires observed across sauropsid lineages. Lastly, I studied the interactions between transposable elements (TEs) and PIWI-interacting RNAs (piRNAs) among laurasiatherian mammals. piRNAs are predominantly expressed in germlines and reduce TE expression and risks associated with their mobilization. I found that within TE types, families that are the most highly transcribed appear to elicit the strongest ping-pong response. This was most evident among LINEs, but the relationships between expression and PPE was more complex among SINEs. I also found that the abundance of insertions within piRNAs clusters strongly correlated with genome insertions and there was little evidence to suggest that piRNA clusters regulated TE silencing. In summary, the piRNA response is efficient at protecting the genome against TE mobility, particularly LINEs, and can have an evolutionary impact on the TE composition of a genome.

The ultrastructural effects of chemical modification on olfactory receptors were investigated with scanning electron microscopy, transmission electron microscopy and fluorescent microscopy. Mason and Morton (1984) hypothesized that a two-step chemical treatment would covalently modify receptor proteins. Their two-step protocol was modified in an attempt to label olfactory receptor proteins and the ultra structural effects of the original two-step protocol were examined.

Empathy represents one multifaceted component of social cognition that is thought to be significantly impaired in individuals with schizophrenia. Psychophysical tasks of smell identification and hedonic processing of pleasant, neutral, and unpleasant odors share common neural networks involved in empathy. Therefore, we investigated the relationship between odor identification, odor ratings, and self-reported empathy in 25 outpatients with schizophrenia and 25 nonpsychiatric individuals. Group differences on empathy scores and unirhinal smell identification performance (with hedonic and intensity ratings) were examined, along with the relationships between smell identification scores, self-reported empathy, and schizophrenia symptomatology. The preliminary findings suggest that individuals with schizophrenia display significant differences from controls on measures of self-reported empathy, odor identification, and hedonic ratings of odors. Deficits in self-reported global and affective empathy were influenced by group and sex, whereas cognitive empathy was reduced across all patients in comparison to controls. Patients displayed reduced unirhinal odor identification accuracy for pleasant but not neutral or unpleasant odors in comparison to controls. Central to the overall aim of the current study, a robust positive correlation was observed between left- and right-nostril hedonic ratings for pleasant odors and self-reported global and affective empathy scores across all participants. In patients, we also found a statistical trend between affective empathy and left-nostril identification accuracy across all odors. Collectively, the results lend support to the role of olfactory-limbic brain regions in the hedonic processing of odors and suggest that aberrant performance observed in schizophrenia may be related to abnormalities in the anatomical and physiological substrates that also subserve empathy.

<p> This thesis is primarily concerned with the problem of recognition among feral Norway rats. Wild rats are known to behave amicably in the presence of colony members and act in a stereotyped aggressive manner towards unfamiliar conspecifics in a territorial context. Previous reports suggest that identity is basically olfactory and is organized around colony-specific odors residing in the nesting material or the metabolic excretions of the male members of a colony.</p> <p> The first experiments in this study were attempts to replicate various reports concerning the maleability of clan odors, thereby giving a wild rat the olfactory characteristics of an alien group and, conversely, to alter a resident's odor such that he was no longer identifiable as a member of his original clan. Further experiments examined identifier and regulator functions of behavioural cues on social interaction subsequent to recognition. The interactions of unfamiliar rats on a mutually common terrain was studied, and compared with that of familiar rats paired on an uncommon territory. The final experiment investigated the functional nature of olfactory stimulation in these situations and compared the reactions of anosmic residents towards familiar and unfamiliar conspecifics.</p> <p> These experiments indicate that recognition is indeed an olfactory process but that identity is highly resistent to alteration. The identifier substance does not appear to be contained in either the nesting matter nor in a colony's urine or feces. Bond of familiarity are not specific to a common terrain and in most cases behavioural cues appear to control the onset and termination of fight behaviour following the olfactory identification. Studies of anosmic residents indicate that novel odors elicit aggressive tendencies while familiar odors are not inhibitors of aggression. The results suggest the presence of a specific male pheromone that is essential for the arousal of aggression while the topography of interaction is regulated largely by the reciprocal behaviours of the animals.</p> / Thesis / Master of Arts (MA)

No description available.

No description available.

<p>Olfactory sensory neurons (OSNs), which detect a myriad of odorants, are known to express one allele of one olfactory receptor (OR) gene (Olfr) from the largest gene family in the mammalian genome. The OSNs expressing the same OR project their axons to the main olfactory bulb where they converge to form glomeruli. This “One neuron-one receptor rule” makes the olfactory epithelium (OE), which consists of a vast number of OSNs expressing unique ORs, one of the most heterogeneous cell populations. However, the mechanism of how the single OR allele is chosen remains unclear along with the question of whether one OSN only expresses a single OR gene, a hypothesis that has not been rigorously verified while we performed the experiments. Moreover, failure of axonal targeting to single glomerulus was observed in MeCP2 deficient OSNs where delayed development was proposed as an explanation for the phenotype. How Mecp2 mutation caused this aberrant targeting is not entirely understood.</p><p>In this dissertation, we explored the transcriptomes of single and mature OSNs by single-cell RNA-Seq to reveal their heterogeneity and further studied the OR gene expression from these isolated OSNs. The singularity of sequenced OSNs was ensured by the observation of monoallelic expression of X-linked genes from the hybrid samples from crosses between mice of different strains where strain-specific polymorphisms could be used to track the allelic origins of SNP-containing reads. The clustering of expression profiles from triplicates that originated from the same cell assured that the transcriptomic identities of OSNs were maintained through the experimental process. The average gene expression profiles of sequenced OSNs correlated well to the conventional transcriptome data of FACS-sorted Omp-positive cells, and the top-ranked expression of OR was conceded in the single-OSN transcriptomes. While exploring cellular diversity, in addition to OR genes, we revealed nearly 200 differentially expressed genes among the sequenced OSNs in this study. Among the 36 sequenced OSNs, eight cells (22.2%) showed multiple OR gene expression and the presences of additional ORs were not restricted to the neighbor loci that shared the transcriptional effect of the primary OR expression, suggesting that the “One neuron-one receptor rule” might not be strictly true at the transcription level. All of the inferable ORs, including additional co-expressed ORs, were shown to be monoallelic. Our sequencing of 21 Mecp2308 mutant OSNs, of which 62% expressed more than one OR genes, and the expression levels of the additional ORs were significantly higher than those in the wild-type, suggested that MeCP2 plays a role in the regulation of singular OR gene expression. Dual label in situ hybridization along with the sequence data revealed that dorsal and ventral ORs were co-expressed in the same Mecp2 mutant OSN, further implying that MeCP2 might be involved in regulation of OR territories in the OE. Our results suggested a new role of MeCP2 in OR gene choice and ratified that this multiple-OR expression caused by Mecp2 mutation did not accompany delayed OSN development that has been observed in the previous studies on the Mecp2 mutants.</p> / Dissertation