Thesis (Ph.D.) -- Australian National University, 2008.

No description available.

The domestic chick became a model for understanding memory, learning and the onset of social behaviours. Just after hatching and for a limited period, the naïve bird seeks a suitable object to imprint. Thanks to laboratory studies, the filial imprinting has been well documented in the very first few hours. However, how the filial imprinting preferences develop and evolve over time remained relatively unexplored. Therefore, we built an automated setup allowing us to follow the animal behaviour across prolonged durations and investigate the stability and variability of filial imprinting preferences. We demonstrated that three days of exposure to artificial objects produce lasting and robust imprinting preferences. With lower imprinting duration, we found that the animal predispositions strongly influence the filial imprinting preferences. Those social predispositions guide the domestic chicks towards living creatures – or at least, towards stimuli conveying animacy. To complete this general pattern, we performed two experiments manipulating motion dynamics. We showed that chicks prefer quickly rotating objects and agents moving with unpredictable temporal sequences: two cues probably used to detect living animals' presence. Both imprinting and social predispositions influence each other, but whether they share a neurophysiological ground was yet to be described. Such as for filial imprinting, we showed that the thyroid hormone T3 strongly affects the sensitive period for animacy preference. T3-inhibition closes the sensitive period for animacy preference and T3-injections re-opens it. Altogether, the present thesis complete previous research on filial imprinting and social predispositions: two distinct but interconnected mechanisms that can help to better understand the mind foundations at the onset of life.

Domestic chicks were tested for initial response, approach, and stay-near tendencies during one 5-minute test exposure to a distant audio-visual 1mprinting apparatus. Significant interline differences demonstrated genetic variation. A bidirectional selection program was initiated with time to respond as the selected trait. Approach and stay-near tendencies were measured as associated traits. Results through the F4 generation disclosed that in the fast response line the realized heritability of the selected trait was .32 and the correlated realized heritabilities for time to approach and for time spent near the apparatus were .36 and .32, respect1vely. In the slow response line selection was ineffective, and heritabilities for the three traits were zero. Genetic and phenotypic relationships among the traits were high in the fast response line, but genetic relationships in the slow response line could not be determined because of the zero heritabilities. The asymmetrical response to selection could not be explained by the usual causes, and it is hypothesized that responsiveness is a threshold trait. Comparisons of 290 purebred chicks with 379 crossbred chicks for response, approach, and stay-near tendencies provided evidence of heterosis. This demonstration of non-additive effects implies fitness roles for these traits and supports the idea that they indicate imprinting tendencies. Time of day tested, sex, hatch, mating type, developmental age, and 24-hr body we1ght were considered independent variables influencing the behavior traits. Multiple regressions showed that the initiation of responsiveness is not predictable. However, once a chick responded, its behavior was highly predictable; this supports the hypothesis from the selection experiment that responsiveness is a threshold trait. Sensory modalities involved in satiating the behavior traits were differentiated by comparisons of non-handled chicks with those exposed to visual, tactile, and visual - plus-tacti1e stimuli just prior to testing. Visual stimulation alone increased responses and approaches, whereas tactile stimulation alone had no effect on these behaviors. Tactile-plus-visual stimulation just prior to testing inhibited response and approach tendencies. Eva1uation of the effects of prior socialization and handling indicated that isolation enhanced approach responses, and that prior handling had the opposite effect. An age and/or memory factor was introduced when chicks were handled in the light at times other than just prior to testing. Handling at 5 and 9 hours had no effect on the approach response, whereas handling at 13, 17. or 23 hours post-hatching decreased such responses. Results were explained on a drive satiation hypothesis. / Ph. D.

Molecularly imprinted polymers (MIPs) have been compared to natural antibodies in that they can specifically bind target compounds in a similar way that antibodies specifically bind to an antigen. The attraction of the MIPs technology is the ease of creating binding elements which are relatively cheap compared with the process of isolating natural antibodies. In this research monoterpenes, such as α-terpineol, were chosen to be the model compounds for investigating the molecular imprinting of small, poorly functionalised organic compounds. The conventional non-covalent approach was mainly used to synthesise these MIPs, but the sacrificial-spacer semi-covalent approach was also investigated. A less widely used method, porogen-imprinting - a variant of non-covalent imprinting - was adapted for α-terpineol. The latter novel terpene MIP appeared to specifically bind α-terpineol, by hydrogen bonding, so the polymer was characterised in detail. The main parameters which were altered for preparing non-covalent MIPs included the template (α-terpineol, (-)-menthol or trans-terpin); the functional monomer (methacrylic acid, 2-hydroxyethyl methacrylate, bilirubin and phenol [for the semi-covalent MIP]); the cross-linking monomer (ethylene glycol dimethacrylate, divinylbenzene and trimethylolpropane trimethacrylate); and also the polymerisation method (block or precipitation polymerisation). The binding specificity and cross-reactivity for all the polymers were tested using a liquid batch-binding setup. The batch-binding setup required the detection of analyte that was not bound in order to calculate by difference the fraction of analyte bound to the polymer. Initially the terpenes were to be detected by a colorimetric method; however attempts to make the method sensitive and reliable were not successful. In comparison, gas chromatography was more reliable for the detection of terpenes and was used for the experiments presented in this thesis. 1H-NMR studies of the interaction between α-terpineol and acetic acid (as a non-polymerisable analogue of methacrylic acid) were investigated as a basis for understanding the binding to the carboxyl functional group moiety employed in many of the non-covalent MIPs that were made. The interaction between (-)-menthol and phenol was also investigated because the phenol moiety was employed in the semi-covalent MIP. Only selected MIPs, which appeared to specifically bind the template, were physically characterised. This included optimising the batch-binding parameters, scanning electron microscopy imaging, surface area and pore radius analysis and in some cases Fourier transform-infrared spectroscopy of the polymers.

No description available.

published_or_final_version / abstract / Chemistry / Master / Master of Philosophy

As optical interconnects make their paces to replace traditional electrical interconnects, implementing low cost optical components and hybrid optic-electronic systems are of great interest. In the research work described in this dissertation, we are making our efforts to develop several practical optical components using novel printing technologies including imprinting, ink-jet printing and a combination of both. Imprinting process using low cost electroplating mold is investigated and applied to the waveguide molding process, and it greatly reduces the surface roughness and thus the optical propagation loss. The imprinting process can be applied to photonic components from multi-mode waveguides with 50[mu]m critical dimension down to photonic crystal structures with 500nm hole diameter. Compared to traditional lithography process, imprinting process is featured by its great repeatability and high yield to define patterns on existing layers. Furthermore we still need an approach to deposit layers and that is the reason we integrate the ink-jet printing technology, another low-cost, low material consumption, environmental friendly process. Ink-jet printing process is capable of depositing a wide range of materials, including conductive layer, dielectric layer or other functional layers with defined patterns. Together with molding technology, we demonstrate three applications: proximity coupler, thermo-optic (TO) switch and electro-optic (EO) polymer modulator. The proximity coupler uses imprinted 50[mu]m waveguide with embedded mirrors and ink-jet printed micro-lenses to improve the board-to-board optical interconnects quality. The TO switch and EO modulator both utilize imprinting technology to define a core pattern in the cladding layer. Ink-jet printing is used to deposit the core layer for TO switch and the electrode layers for EO modulator. The fabricated TO switch operates at 1 kHz with less than 0.5ms switching time and the EO modulator shows V[pi][middle dot]L=5.68V[middle dot]cm. To the best of our knowledge, these are the first demonstrations of functional optical switches and modulators using printing method. To further enable the high rate fabrication of ink-jet printed photonic and electronic devices with multiple layers on flexible substrate, we develop a roll-to-roll ink-jet printing system, from hardware integration to software implementation. Machine vision aided real time automatic registration is achieved when printing multiple layers. / text

No description available.

Long noncoding RNAs (lncRNAs) are being realized as important players in gene regulation and their misregulation has been considered as one of the underlying causes for tumor initiation and progression in many human pathologies. In the current thesis, I have addressed the functional role of lncRNAs in development and disease model systems. Genomic imprinting is an epigenetic phenomenon by which subset of genes are expressed in a parent of origin-specific manner. The Kcnq1 imprinted locus is epigenetically regulated by Kcnq1ot1 lncRNA. Deletion of an 890bp region at the 5’ end of Kcnq1ot1 in mouse resulted in the loss of silencing of neighboring ubiqui-tously imprinted genes (UIGs). In addition, we observed loss of DNA methylation at the UIG promoters. We have shown that Kcnq1ot1 RNA establishes CpG methylation by interacting with DNMT1. To explore the stability of lncRNA mediated silencing pathways, we have conditionally deleted Kcnq1ot1 in the mouse in a stage and tissue-specific manner. We have shown that Kcnq1ot1 is continuously required for maintaining the silencing of UIGs, whereas the silencing of the placental im-printed genes is maintained in an RNA independent manner.   To identify chromatin-associated lncRNA (CARs) on a genome-wide scale, we purified RNA from the sucrose gradient fractionated chromatin and subjected it to RNA sequencing. Our study has identified 141 intronic and 74 long intergenic CARs. Characterization of one of the CARs revealed that it regulates the expression of neighboring genes in cis by modulating the chromatin structure.   We have explored the functional role of lncRNA in tumor progression and initiation by using pediatric neuroblastoma. By transcriptional profiling of low- and high-risk tumors, we have identified several lncRNAs differentially expressed between these subtypes. We report an uncharacterized RNA NBAT-1, expressed at lower levels in high-risk tumors relative to low-risk tumors.  Using neuroblastoma cell culture system, we demonstrated that NBAT-1 has anti-cell proliferative and anti-invasive properties. In addition, it promotes differentiation of neurons from undifferentiated neuroblastoma cell lines.   In summary, by employing mouse genetics, cell culture based model system and expression profiling in tumors, we have uncovered new roles of lncRNA in gene regulation.