Genetics - Theses
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ItemStudies on minor non-metrical skeletal variants in the mouse and man(University of Melbourne, 1970)This thesis consists of papers presenting the results of studies on the genetical, developmental and anthropological aspects of minor non-metric al variants in man and the house mouse. The work is mainly on variants of the skeleton, particularly the cranium, but includes a limited discussion of published data on minor non-metrical variants of the muscular and vascular systems. Each study is based on a number of variants, and, where applicable, single measures have been obtained to express the overall difference in skeletal variability between populations or the overall effect on skeletal variability of certain environmental factors. Investigations into the role of genotype and environment in the determination of minor skeletal variants in mice and man indicate that most of them are under some genetic control but that maternal physiology and other non-genetic factors may influence the frequency of individual variants. Data presented here (Publication 1) on 25 minor skeletal variants in inbred strains of mice and their hybrids suggest that genotype is more important than environment in determining skeletal variability. Although the frequency of a few individual variants was found to be significantly affected by certain non-genetic factors, when many variants were considered together the environment had no overall significant effect. In contrast, large differences, due mainly to genetic factors, were observed between inbred strains and hybrids. Further studies on inbred strains of mice and hybrids (Publication 2) indicate that stabilizing mechanisms operate during the formation of the skeleton. For most of the 29 bilateral minor non-metrical variants studied , the frequency of asymmetrical mice (i.e., those with the variant present on only one side) was less than expected on the assumption that the number of mice with the variant present on both, one or neither sides depends solely on the frequency of the variant on each side. This tendency for the development of the skeleton to be canalized against asymmetry has been described as a form of morphogenetic homeostasis. The same phenomenon has been observed for bilateral minor non-metrical variants in man (Publication 3) for the skeletal, muscular and vascular systems (based on data published by Danforth in 1924) and for the skeletal system of Australian Aborigines. Studies on inbred strains of mice (e.g., Publication l) indicate that genotype plays the major role in determining the frequency of minor non-metrical variants. If these findings can be extrapolated to man, minor non-metrical variants may be of use in anthropological work. A general survey of skeletal variation, based on 30 such variants, was carried out on Aboriginal crania from many parts of Australia (Publication 4). Regional differences in the pattern of cranial morphology were observed which appear to culminate in two extreme populations: one in the north and north-west of the continent, the other in south-eastern Australia. These results were considered in relation to some current theories on the origin and ethnic composition of the Australian Aborigines.
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ItemNo Preview AvailableCharacterization of the DNA of normal and transformed cells of the black-tailed wallaby, protomnodon bicolor(University of Melbourne, 1977)
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ItemNo Preview AvailableContributions to the development of hormonal insecticides : the biosynthesis and mode of action of the ecdysones(University of Melbourne, 1974)During the last 10 years, the candidate's interests have centered on problems of the regulation of gene activity during cytodifferentiation in insect tissues. Certain higher Diptera offer especially good opportunities for studies of this kind: developmental pattern of the Holometabola permit the same genome to be studied in larval and imaginal differentiation and morphogenesis, many larval and pupal tissues have well developed polytene chromosomes so that biochemical and cytological correlations are facilitated, the individuals are of reasonable size and the generation time is short. These features led the candidate to select the Australian brown blowfly, Calliphora stygia, as the experimental material for an extensive and broadly based study of gene action during development. While this experimental system was being developed, Dr. D. H. S. Horn of the Division of Applied Chemistry, CSIRO, was expanding his project on the chemistry and biosynthesis of the insect moulting hormones, with the long-term goal of developing insecticides based on moulting hormones, their analogues, inhibitors or competing compounds. Dr. Horn's team required biological support for their chemical studies along three main lines: (i) preparation of accurately aged samples for studies of endogenous hormone levels and the biosynthetic pathway of moulting hormone in a holometabolous insect (ii) a reliable bioassay to permit comparison of the relative activities of various ecdysones and their analogues (iii) a physiologically defined test-preparation in which isotopically labelled compounds could be tested for ability to serve in vivo as precursors for moulting hormone biosynthesis. Each of these requirements was compatible with the aims of our study on Calliphora at the University of Melbourne, so that collaboration with the CSIRO group rapidly developed. In addition, the availability of quantities of carefully purified moulting hormone through Dr. Horn's work provided the basis for our studies on the mode of action of the moulting hormones on individual larval tissues, especially in relation to protein and RNA synthesis. The contributions of the various workers involved in these projects to the publications presented here are summarized below: Section 1 Introduction: Ideas presented here were developed by Thomson in an invited lecture contributed to Symposium 4, 14 International Congress of Entomology, Canberra, 1972. Paper 1 represents the published abstract of this lecture. Section 2. The Bioassay of Insect Moulting Hormones: Papers 2-3 are based on experimental work conceived by Thomson, carried out in collaboration with Imray in Thomson's laboratory and were written up by Thomson. Pure crystalline ecdysones were provided by Horn. Section 3. The Mode of Action of Insect Moulting Hormones: Papers 4-8 represent work planned and executed in Thomson's laboratory using pure hormone samples provided by Horn. All papers were written by Thomson. Experimental work for paper 4 was done by Thomson. For paper 5, much of the laboratory work on the time-course of response of protein synthesizing activity in individual tissues was done by Neufeld in consultation with Thomson; the latter did the subcellular fractionation and collected one set of dose-response data. For paper 6, Thomson carried out the incorporation experiments, made the squash preparations and sections for radioautography, and interpreted the results. Gunson contributed cytological observations on the nuclear membrane, and Rogers did the electron microscopy. Pure radio-labelled ?-ecdysone was prepared by Horn from extracts of animals treated in Thomson's laboratory with �-ecdysone of high specific activity. Paper 7 is based on experimental work planned by Thomson and carried out jointly with Kinnear and Martin who were largely responsible for the electrophoretic part of the study; the results were analyzed by Thomson. Paper 8 represents a synthesis of the studies grouped in this section. Section 4. The Biosynthesis and Catabolism of Insect Moulting Hormones: Papers 9-20 are based on work arising largely at the initiative of Horn and his collaborators, principally Galbraith and Middleton. Experiments were planned in consultation with Thomson, who provided, treated, timed and harvested all experimental animals in his laboratory, but whose role in this work was clearly subsidiary. All purified hormone preparations and analogues were made, and chemical syntheses done, by Horn and colleagues at CSIRO; these workers were also responsible for the major portion of writing of the resulting papers. Thomson performed all bioassays, and contributed those paragraphs to each paper which are primarily concerned with the animals used, the response of individual tissues, and with certain aspects of the biological significance of the results.
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ItemChromosome studies on institutionalised persons(University of Melbourne, 1971)
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ItemFunction and development of insect fat body(University of Melbourne, 1969)
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ItemNo Preview AvailableSome aspects of human variation in growth and dermatoglyphics(University of Melbourne, 1969)Means and standard deviations of pattern intensity index and total ridge-count are presented for a limited sample of full-blood Western Australian Aborigines from a mission station near Wiluna. The results are compared with those found by previous workers.
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ItemNo Preview AvailableSerological variation in calliphora populations(University of Melbourne, 1968)
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ItemThesis for MSc degree(University of Melbourne, 1966)Hymenopteran cytogenetics has been hampered by the small size of the chromosomes, the technical difficulties associated with obtaining cell divisions (spermatogenesis, for Instance, is complete by the end of pupal life, except in a few species), and by the fact that true meiosis does not occur in the male and hence must be studied in the female, requiring more elaborate techniques. In fact, males are genetically equivalent to gametes of the females, which can be considered hermaphrodites from the standpoint of population genetics (Crow and Roberts 1950; Cale and Gowen 1964). The present work has been concerned with interspecific relationships as seen in mitotic chromosomes. The cytotaxonomic study of ants has been firmly established only recently with the papers of Hauschteck (1961, 1962, 1963), and Imai and Yosida (1964), although there have been other groups working on ant chromosomes (Smith and Peacock 195?; Whelden and Haskins 1953; Kumbkarni 1965). There has been no work published on the use of colcemid in ant cytotaxonomy. The information obtainable about chromosome morphology has therefore, generally been limited to size comparisons and chromosome counts have formed the principal basis for interspecific comparisons. Most attention to date has been focussed on species of the two largest subfamilies, the Myrmicinae and Formicinae. Emphasis in the present work, however, has been on species of the subfamilies Dolichoderinae and Ponerinae.
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ItemNo Preview AvailableChromosomal polymorphism in Victorian chironomids(University of Melbourne, 1961)