Thesis (M.S.) in Zoology--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 33-36).

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Bibliography: p. 133-141. A genetic and molecular characterisation of the Drosophila gene starvin', focussing on analysis of the sequence of starvin', characterisation of the embryonic localisation of starvin' protein, and the identification and phenotypic characterisation of starvin' mutants.

Thesis (Ph. D.)--University of Oregon, 2000. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 103-113). Also available for download via the World Wide Web; free to University of Oregon users.

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Memoria para optar al Título Profesional de Médico Veterinario / El control de la transcripción génica en tejido neural y no neural, permite que los genes que codifican para proteínas de expresión exclusiva, se expresen de ésta forma. En el caso de genes de expresión neuronal-específica, se logra por medio de factores de transcripción que ejercen control positivo (activan la transcripción en tejido neuronal) o negativo (reprimen la transcripción en tejido no neuronal). Dentro de los factores descritos como reguladores negativos de la expresión de genes neuronales en tejido no neuronal se encuentra Represor Element 1 Silencing Transcription Factor (REST), que recluta dos tipos de complejos remodeladores de la cromatina: mSin3 y CoREST. Evidencia in vitro sugiere que éste último es fundamental para que REST ejerza su función represora. En esta memoria se utilizó Drosophila melanogaster como modelo de estudio para evaluar la importancia in vivo de este co-represor por medio de la inhibición de su síntesis mediante RNA interferente (iRNA). El estudio se realizó en el tejido alar de Drosophila melanogaster evaluando las alteraciónes morfológicas y cambios de expresión de genes neuronales y no neuronales para acercarse al estudio de la vía de transducción de CoREST. Los resultados obtenidos sugieren que in vivo, CoREST es fundamental para el desarrollo de venas del ala y la especificación neuronal / Financiamiento: Proyecto NEMO-ICMP07-048-F

The new mutation, synpalpi, which was found in the Xple Stock obtained from the Biological Supply House, Chicago, is so named because of the fusion of the antennae along the midline, all other Xple characteristics being normal except for a slight protrusion of the forehead. In stock cultures the mutant appears in greater numbers from normal Xple crosses than from synpalpi Xple crosses - with a predominance of female synpalpi. Experiments were carried out in order to determine the nature of the mutation, the type of inheritance involved, and the linkage group with which the mutation is associated. The mutant is not a gene mutation but a chromosomal aberration since Mendelian ratios were not observed to occur and since the mutation appeared irregularly but persistantly. A lethal factor is suggested by the small number of flies resulting from synpalpi crosses; the absence or small number of synpalpi in the F¹ of synpalpi crosses but its reappearance in 2-8% of the F² progeny; and by the death of flies in two different stages of development - early and late pupal stages. The association of the lethal factor with the "X" chromosome is assumed because few male synpalpi emerge. A deficiency of a part of the "X" chromosome would explain the death of the males and homozygous females. The possibility of a deficiency of a few bands at the tip of the “X” chromosome was substantiated by a review of the literature on deficient "X" chromosomes. It is believed that synpalpi flies are those deficient flies which do manage to survive and that the fused antennae are caused by the movements of the fly and forcing of fluid to the head in its efforts to extricate itself from the pupa case (its tracheae being attached posteriorly to the case). The Xple stock is very sensitive to variations from the optimum temperature of 25°C. Temperatures of 35°C., 29°C, and 15°C. increased the lethal effect of the deficiency - no synpalpi appearing in the F¹ or F² of temperature-treated cultures. In the test for linkage, the mutant appears to be associated with chromosomes I and III - therefore the mutant is not a simple deficiency of the "X" chromosome alone but appears to involve the third chromosome as well. / Science, Faculty of / Botany, Department of / Zoology, Department of / Graduate

Experimental components analysis (Holling 1966) is used to develop a computer model of the four processes of sexual reproduction: mating, egg production, egg fertilization, and oviposition site selection. A general function of interacting populations is developed, and its application to mating and oviposition site selection is discussed. Data from the literature on mating are used to estimate parameter values for this function. A model of egg production and egg fertilization is developed from an experimental study of the vg strain of Drosophila melanogaster. Egg production is a complex process consisting of four components affecting individual ovarioles: ovariole activation, ovariole production, vitellegenesis, and ovariole deactivation. Threshold effects are found to exist for all four components. Egg fertilization is a simple process involving number of sperm stored and a constant probability of successful fertilization. However, results indicate that both egg fertilization and egg production become more complex beyond the range of treatments used here. Assumptions, not supported by data, are made for the processes of oviposition site selection, aging, mortality, and development. These assumptions are combined with the models of mating, egg production, and egg fertilization into a single tentative model for sexual reproduction. Simulations using this model suggest possible effects of ecological importance: a sigmoid relationship between reproductive rate and density; and a chance in tactics with increasing mortality due to predation. / Science, Faculty of / Zoology, Department of / Graduate

The autonomous behaviour of sex-linked recessive temperature-sensitive lethal mutants in Drosophila melanogaster could be demonstrated by the presence of mosaic patches of tissue hemizygous for the mutant created by loss of a ring X chromosome in cells at the permissive temperature (21.5°C) and the absence of such patches at the restrictive temperature (29°C), The presence of patches at both temperatures indicated that the mutant was non-autonomous. Such non-autonomous behaviour might be attributed to the existence of a substance capable of diffusing from the wild type tissue to supplement the mutant tissue. The experiments carried out showed that the presence or absence of mosaic patches could not be directly interpreted as demonstration of autonomous or non-autonomous properties of the mutant. Other factors such as the time of activity of the ts mutant and the type of tissue undergoing ring X loss affected mosaic tissue production. Therefore, the mere presence of mosaic tissue at 29°C could not be used as a criterion for the non-autonomous behaviour of the ts mutants. However, these mutants can be graded according to the degree of autonomy of ts lethality after alterations due to XO survival frequencies, lethal periods, and temperature-sensitive periods have been placed onmosaic frequencies at 29°C. Of the thirteen ts mutants studied, six can he classed as autonomous lethals. The others are equally autonomous as lethals but only in specific tissues, while others do not appear to be as autonomous. In fact, one of these may be considered non-autonomous. / Science, Faculty of / Zoology, Department of / Graduate

Heterochromatin can be described cytologically as those chromosomes or parts of chromosomes which remain heteropycnotic, or dark staining, through most of the cell cycle. Genetically and biochemically heterochromatic regions generally seem to be inert and it has been suggested that many heterochromatic loci are duplicated several times. In micro-organisms, genetic and biochemical analyses have been greatly facilitated by the use of conditional lethals which survive under "permissive" conditions but die under "restrictive" conditions. Temperature-sensitive ethyl methanesulfonate-induced lethal mutations (such mutants result in survival at 22°C but death at 29°C) have previously been used in Drosophila melanogaster for preliminary studies of development. In the present study 8 temperature-sensitive (ts) sterile mutations (males are fertile at 22°C but sterile at 29°C) were induced on the Y chromosome of D. melanogaster. The ts mutants were mapped genetically on the long arm of the Y chromosome and they were found to involve a minimum of 4 different loci. The Y chromosome of D. melanogaster is entirely heterochromatic and it is necessary for male fertility but the exact function of the Y chromosome is uncertain. The recovery of point mutations (ethyl methanesulfonate-induced temperature-sensitive mutations are presumed to be point mutations) on the Y chromosome indicates that there are loci on the Y represented by a single copy. A determination of the specific developmental effects of the ts sterile mutations, was also attempted. By exposing mutant males to a 48 hour period under the restrictive conditions (29°C) and observing their fertility for several days, the stage in the production of mature sperm during which the ts mutants were having an effect, was determined. / Science, Faculty of / Zoology, Department of / Graduate