Global ETD Search

11	Investigating Molecular Evolution of Rhodopsin Using Likelihood/Bayesian Phylogenetic Methods Du, Jingjing 22 July 2010 (has links) Rhodopsin, a visual pigment protein found in retinal photoreceptors, mediates vision at low-light levels. Recent studies focusing primarily in human and mouse have challenged the assumption of neutral evolution of synonymous substitutions in mammals. Using recently developed likelihood-based codon models accounting for mutational bias and selection, we find significant evidence for selective constraint on synonymous substitutions in mammalian rhodopsins, and a preference for cytosine at 3rd codon positions. A second project investigated adaptive evolution in rhodopsin, in view of theories of nocturnality in early mammals. We detected a significant acceleration of non-synonymous substitution rates at the origins of therian mammals, and a tendency of synonymous substitutions towards C-ending codons prior to that. These findings suggest an evolutionary scenario in which synonymous substitutions that increase mRNA stability and/or translation efficiency may have preceded adaptive non-synonymous evolution in early mammalian rhodopsins. These findings have important implications for theories of early mammalian nocturnality. Molecular Evolution Likelihood and Bayesian methods Phylogenetics Rhodopsin Natural Selection Codon Usage Bias Nocturnality Early mammals Visual Pigment Adaptive Evolution Vision GPCR 0715 0307 0369
12	Investigating Molecular Evolution of Rhodopsin Using Likelihood/Bayesian Phylogenetic Methods Du, Jingjing 22 July 2010 (has links) Rhodopsin, a visual pigment protein found in retinal photoreceptors, mediates vision at low-light levels. Recent studies focusing primarily in human and mouse have challenged the assumption of neutral evolution of synonymous substitutions in mammals. Using recently developed likelihood-based codon models accounting for mutational bias and selection, we find significant evidence for selective constraint on synonymous substitutions in mammalian rhodopsins, and a preference for cytosine at 3rd codon positions. A second project investigated adaptive evolution in rhodopsin, in view of theories of nocturnality in early mammals. We detected a significant acceleration of non-synonymous substitution rates at the origins of therian mammals, and a tendency of synonymous substitutions towards C-ending codons prior to that. These findings suggest an evolutionary scenario in which synonymous substitutions that increase mRNA stability and/or translation efficiency may have preceded adaptive non-synonymous evolution in early mammalian rhodopsins. These findings have important implications for theories of early mammalian nocturnality. Molecular Evolution Likelihood and Bayesian methods Phylogenetics Rhodopsin Natural Selection Codon Usage Bias Nocturnality Early mammals Visual Pigment Adaptive Evolution Vision GPCR 0715 0307 0369
13	Awareness about diabetic retinopathy and retinal screening among female diabetic patients attending the diabetic clinic in a day hospital in Cape Town, South Africa Mkhombe, Nomfundo Fortunate 11 1900 (has links) A non-experimental quantitative, descriptive and contextual study which sought to examine the level of awareness about Diabetic Retinopathy (DR), and how aware female diabetic patients were about retinal screening as a preventative measure to eye complications and blindness was conducted. The objective of the study was to explore and describe the variables related to the awareness level of female diabetic patients about Diabetic Retinopathy and diabetic retinal screening. A convenient sample of 149 respondents was obtained. A questionnaire was used to collect data. Data was analysed using the Statistical Package for Social Sciences (SPSS), 13.0 computer software program. Results evidenced a good level of awareness about DR. Recommendations based on the findings were made for consideration in clinical practice, education and research. / Health Studies / M.P.H. Awareness Diabetes mellitus Diabetic retinopathy Female patients Retinal screening 617.73509687355 Retinal (Visual pigment)

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