Genetics - Theses

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Studies on minor non-metrical skeletal variants in the mouse and man

Kellock, Wendy Lorraine. (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.
Characterization of the DNA of normal and transformed cells of the black-tailed wallaby, protomnodon bicolor

Newton, Gail. (University of Melbourne, 1977)
Patterns of protein synthesis in larval and imaginal tissues of Calliphora : an analysis of gene activity during differentiation and development in a holometabolous insect

Martin, Marjorie-Dore (University of Melbourne, 1975)

This study attempts to develop a logically consistent approach to the analysis of the genetic basis of complete metamorphosis in holometabolous insects,using the Australian brown blowfly, Calliphora stygia (Diptera), as the experimental organism. The following aspects of the problem have been examined: 1. Definition of the protein and enzyme spectra of selected larval and imaginal tissues during development. 2. Identification of the homologous gene products amongst various tissues with the view to establishing the uniqueness or overlap of gene readout in the series of tissues. 3. Identification of the times of synthesis of gene products as distinct from the duration of their occurrence leading to a definition of overall patterns of gene activities in the series of tissues. 4. Investigation of a specific model system for hormone action in vitro, namely with fat-body tissue and moulting hormone (MH). Current genetic models of insect metamorphosis have been examined in the light of the findings in this study of C. stygia.
Contributions to the development of hormonal insecticides : the biosynthesis and mode of action of the ecdysones

Thomson, J. A. (John Alexander), 1934- (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.
Parthenogenesis, chromosomal polymorphism and morphological variation in Chironomids

Porter, David Laurence. (University of Melbourne, 1973)

Parthenogenesis, in the forms of arrhenotoky, deuterotoky, or thelytoky, is a quite common phenomenon in the animal kingdom. Thelytoky, in which females produce exclusively female progeny in the absence of genetic fertilization, is the most widespread and most mechanistically diverse form of parthenogenesis. It does not follow that thelytoky is the most common ; arrhenotoky, which only occurs in one rotifer, one arachnid and four insect orders (Hartl 1971), is probably the most successful form of parthenogenesis in terms of numbers, due mainly to the presence of over 100,000 species of hymenopterans, the vast majority of which are arrhenotokous. Thelytoky itself is present in a wide variety of forms. The mechanism for the maintenance of thelytoky may be automictic, in which at least the first meiotic division is normal, the chromosomes pairing at prophase and forming bivalents. The zygoid phase is restored by the restitution of anaphase I or metaphase II chromosome plates, fusion of second division products or endomitosis in cleavage nuclei. Alternatively the mechanism may be apomictic, in which meiotic features may be partly or wholly absent, the one or two maturation divisions being equational. Thelytoky may be complete, it being the only manner of reproduction; or it may be cyclical, where it alternates either regularly, or under the influence of environmental factors, with amphimixis or arrhenotoky. Thelytoky may also be either facultative or obligatory. Facultative thelytoky is the situation whereby reproduction is normally bisexual, however a percentage of eggs may develop without fertilization. Obligatory thelytokous forms produce all their offspring without genetic fertilization, reproduction can therefore never be bisexual. There are many thelytokous forms in which the eggs require penetration by the sperm of the same or related species before they develop. In this case, gynogenesis, the sperm makes no chromosomal contribution to the embryo, although there is a cytoplasmic contribution which may have some effect. In this chapter there are two main areas to be examined. The first is to investigate the cytology of two members of the chironomid subfamily Chironominae, Lundstroemia parthenogenetica and Lauterbornia sp. , and to compare them to other thelytokous forms with analogous maturation mechanisms, especially the members of the subfamily Orthocladiinae described by Scholl (1956, 1960). The second area is the discussion of the evolution and properties of thelytokous organisms. Most review articles tend to be limited to a broad presentation of the magnitude of the phenomenon (Oliver 1971), but also order the paper from the point of view of mechanism or animal groupings. Here the discussion is ordered from the point of view of the importance of various phenomena in the evolution and maintenance of thelytokous forms, e.g. hybridization, genetic and ecological considerations. This may not be a more systematic mode of presentation, but it seems to me to be more logical.
Determination and differentiation in imaginal discs of holometabolous insects, literature review ; changes in some specific proteins during development of third instar larvae of the blowfly Calliphora stygia, research report

Dugan, P. R. (Patrick R.) (University of Melbourne, 1971)
Chromosome studies on institutionalised persons

Sutherland, Grant R. (University of Melbourne, 1971)
Cytogenetic and evolutionary studies on macropathinae (gryllacridoidea : orthoptera)

Mesa, Alejo. (University of Melbourne, 1970)

The Gryllacridoidea are a very ancient and diverse assemblage. One of the four families included in it, the Sohizodactylidae, is confined to the Old World, while the other three, Stenopelmatidae, Gryllacrididae and Rhaphidophorinae, have a world-wide distribution. The latter family Is divided into the subfamilies Ceuthophilinae from North and Central America, Rhaphidophorinae mainly from Europe and Asia, and Macropathinae with a circum-antarctic distribution. Up to date, less than one hundred species of Macropathinae have been described, the majority of them from New Zealand and the surrounding islands. Fourteen species were described from the East and South of Australia including Tasmania and Flinders Island. A few species are from the Southern cone of South America while only one species has been described from Africa, in Cape Town. The majority of these species are forest inhabitants with nocturnal habits. During the day they hide in dark and humid places like hollow logo and or crevices. Caves and tunnels make a suitable place for then to hide in and reproduce. Their density in those places is sometimes remarkable and hence their fame of being mainly cave inhabitants. To collect these insects in forest is more difficult due to the fact that their populations are more scattered. The Macropathinae, like the remaining rhaphidophorids, are wingless. Their body length range from less than 1 cm. to nearly 5 cm. The length from the tip of the antennae to the hind tarsi reaches 45 cm in Gymnoplectron giganteum (Richards 1962). Information on chromosome numbers and chromosomal sex-determining mechanisms in gryllacridids other than Macropathinae is summarised in Table I. According to these data, the chromosome number varies widely from family to family and even within families. The majority of these papers deal with chromosomes at metaphase, information about the fine structure of chromosomes at prophase being very scarce. In the present study a survey on the chromosomes and terminal abdominal segments within Macropathinae was undertaken in order to find possible phylogenetic relationships within the subfamily. Sometimes it was unavoidable to enter the taxonomic field. In this respect, only the genera Miotopus, Pleioplectron and Weta wore fully treated. When new genera end species were involved, a brief, preliminary description was included. Nearly seventy species were investigated, about half of them being new species. About a dozen New Zealand new genera were discovered as well. Approximately fifteen hundred specimens were handled from which nearly four hundred were cytologically investigated. The description of this amount of species will undoubtedly take a long time and falls outside the scope of the present study, which must be only considered a preliminary report.
Function and development of insect fat body

Martin, Marjorie-Dore. (University of Melbourne, 1969)
Some aspects of human variation in growth and dermatoglyphics

Propert, David, 1942- (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.

Genetics - Theses

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