Dissertationen: „Drosophila Molecular genetics“

1

Johnstone, Oona. „Characterization of the Vasa-eIF5B interaction during Drosophila development“. Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84265.

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Translational control is an important means of regulating gene expression. Development of the Drosophila germ line relies on translational regulation to differentially express maternal mRNAs, allowing it to develop distinctly from the soma. One of the critical factors required for germ cell development and function is the conserved DEAD-box RNA helicase Vasa (Vas). The research presented in this thesis examines the role of Vas in translational regulation during Drosophila germ line development. A two-hybrid screen conducted with Vas identified a translation initiation factor eIF5B (dIF2), as a direct interactor. Mutations were created in eIF5B and were found to enhance the vas mutant phenotypes of reduced germ cell numbers, and posterior segmentation defects, suggesting a functional interaction between these factors in vivo. In order to further understand the biological significance of the Vas-eIF5B interaction, the region of Vas required for eIF5B-binding was mapped and then specifically disrupted. Reduction of Vas-eIF5B binding using a transgenic approach, virtually eliminated germ cell formation, while having only a moderate effect on the somatic requirement of Vas in posterior segmentation. In addition, Vas-eIF5B interaction was found to be required for the establishment of polarity within the egg during oogenesis, likely through direct regulation of gurken (grk) mRNA. We concluded that through interaction with eIF5B, Vas plays a critical role in translational regulation in the germ line. In addition, another Drosophila DEAD-box protein, highly similar to Vas, called Belle (Bel) was characterized. Mutations in bel were found to also affect the germ line, leading to both female and male sterility. Like Vas, Bel is implicated in translation initiation, however bel is an essential gene, with a requirement for growth, whose function is not restricted to the germ line. Our data suggest that Bel may be a nucleocytoplasmic shuttling protein,

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2

Zhang, Li. „DRMT4 (Drosophila arginine methyltransferase 4) : functions in Drosophila oogenesis“. Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80905.

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DRMT4 (Drosophila Arginine MethylTransferase 4) is an arginine methyltransferase in Drosophila (Boulanger et al. 2004). It shows the highest identities with mammalian PRMT4/CARM1 (Protein Arginine MethylTransferase 4) (59% identity, 75% similarity). HPLC analysis demonstrated that DRMT4 belongs to the type I class of methyltransferases (Boulanger et al. 2004), meaning that DRMT4 catalyzes asymmetrical dimethylarginine formation. A polyclonal antibody against DRMT4 was generated and used to study DRMT4 expression using western blots and immunostainings. In order to study DRMT4 function in Drosophila using genetic methods, we created three kinds of DRMT4 transgenes: a genomic DRMT4 under its own control, a genomic DRMT4-GFP fusion gene and a cDNA DRMT4 under UAS control. We investigated DRMT4 localization in wild type flies using the DRMT4-GFP transgenic line and immunostaining.

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3

Tauber, Merav. „Molecular genetics of aggressive behaviour in Drosophila melanogaster“. Thesis, University of Leicester, 2010. http://hdl.handle.net/2381/10224.

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Aggression is a key component of the normal repertoire of behaviours in a broad range of animals from insects to mammals. Although the genetic basis for aggression is widely accepted, only a few individual candidate genes have been studied. Recent studies have indicated that Drosophila melanogaster can serve as a powerful model system to study the genetics of aggression. The aim of this project was to identify genes associated with aggression by global profiling of the fly transcriptome using DNA expression microarrays. At the core of this study was a behavioural screen in which the aggression of 910 pairs of males was observed and scored. Microarray analysis revealed 350 genes that were differentially expressed between aggressive and nonaggressive flies. Several biological functions such as translation activity, immune response, ion transport, and sensory transduction were significantly over-represented. Analysis of the upstream region of these genes also suggested several shared motifs that might serve as transcription factor binding sites that drive the co-expression of these genes. One of the top differentially expressed genes was Dat, (dopamine-Nacetyltransferase), which was upregulated in aggressive flies. Dat has two isoforms generated by alternative splicing, DatA and DatB. QPCR analysis revealed that only DatB is upregulated in aggressive flies. In Datlo mutants that express only DatB, aggression is also increased, an effect that can be reverted by over-expressing the DatA transgene. Additional experiments over-expressing DatB indicate that the two isoforms effectively act in opposite ways to regulate aggression, suggesting that a balance between them is necessary for adaptive levels of aggression. Another candidate gene was CG6480, whose levels were reduced in aggressive flies. The function of this gene is unknown, but it does share a conserved motif called Fascin with its mammalian ortholog frg1. Silencing this gene by dsRNAi resulted in flies that show elevated levels of aggression.

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4

Sun, Qi Zinn Kai George. „Molecular genetics of axon guidance in Drosophila melanogaster /“. Diss., Pasadena, Calif. : California Institute of Technology, 2000. http://resolver.caltech.edu/CaltechETD:etd-03242005-130557.

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5

Freeman, Sally Jean. „Molecular analysis of the Drosophila gene, Polyhomeotic“. Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27924.

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Polyhomeotic (ph) is a developmentally important gene in Drosophila melanogaster which has been genetically characterized and recently cloned. ph is genetically and molecularly complex and has a strong maternal effect. Analysis of null or amorphic alleles reveal phenotypic effects that include embryonic lethality, cell death of the ventral epithelium, homeotic transformations, and alteration in the pattern of axon pathways. Two independent point mutations are required to produce a ph null allele. I have shown that the ph locus contains two, large, highly conserved, tandem repeats that are both transcribed. I have identified transcripts that are altered in ph mutants and that are developmentally regulated. Fourteen cDNA's have been isolated, and mapped. Northern and Southern blot analysis, and comparisons between cDNA and genomic restriction maps shows that the cDNAs represent at least 4 different transcripts that include distinct products of both repeats as well as non-repeated sequence. Both the genetic behavior and molecular organization of the ph locus are unique in Drosophila.
Science, Faculty of
Zoology, Department of
Graduate

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6

Stevens, Naomi Rosalie. „The molecular regulation of centriole duplication in Drosophila“. Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611818.

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7

Loh, Samantha Hui Yong. „Molecular and genetic characterisation of Drosophila Sox50E and Sox100B“. Thesis, University of Cambridge, 2000. https://www.repository.cam.ac.uk/handle/1810/251700.

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8

Ditch, Lynn Marie. „Molecular genetics of mutations altering sexual behavior in Drosophila /“. Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3071049.

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9

Howard, K. R. „Molecular genetics of the hairy locus of Drosophila melanogaster“. Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38040.

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10

Harley, Alyssa Skye. „Analysis of a nuclear role for 'pebble', a gene required for cytokinesis in Drosophila“. Title page, abstract and table of contents only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phh284.pdf.

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"May 2002" Bibliography: leaves 157-176. Through the use of a variety of biochemical and genetic techniques, the importance of the nuclear localisation of PBL was examined, as well as the function of its RadECl and BRCT domains. The RadECl/BRCT domains were found to be required in the cytoplasm for cytokinesis, extending the range of function attributed to these domains. PBL was also shown to shuttle between the nucleus and the cytoplasm, providing an explanation for the observed ability of nuclear PBL to influence cytoplasmic structure.

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11

Jud, Molly Christine. „Jun signaling during Drosophila development“. Thesis, The University of Utah, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10130207.

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Jun N-terminal kinase (JNK) signaling is a key modulator of development and disease in all multicellular organisms. One process in which the consequences of both gain and loss of JNK signaling can be monitored is embryonic dorsal closure (DC) in the fruit fly, Drosophila melanogaster. DC occurs midway through embryogenesis; it is the process by which the lateral epidermis expands bilaterally to meet and fuse at the dorsal midline, thereby encasing the entire embryo in epidermis. JNK signaling in leading edge (LE) cells (the dorsal-most row of epidermis) initiates closure. My studies of a novel but conserved JNK signaling antagonist, Raw, have provided several unique insights into: 1) Jun function as a component of the AP-1 transcription factor, and 2) the role of the epidermis as a signaling template mediating development of the epidermis and adjacent tissues.

My graduate work has built upon the demonstration that raw is required to prevent promiscuous JNK signaling in the embryonic epidermis just prior to DC. I have shown that raw is necessary for proper accumulation of Jun in LE cells required to define the LE, which functions as a signaling center required for epidermal closure as well as for underlying heart development. I have gone on to show that Jun accumulates at previously unrecognized sites in the embryonic epidermis, including tracheal pits and solitary epidermal cells lying directly above the peripheral nervous system (PNS). Jun activity is required for tracheal and nervous system defects observed in mutants of two JNK signaling antagonists, raw and rib, and indicates that cell signals within and to an adjacent tissue are integral to proper development. I have found that the epidermis plays an instructive role during development, and results from my work have led to insights into how JNK signaling centers in the epidermis coordinate morphological processes.

As Raw is a novel but conserved JNK signaling antagonist, I have built and tested models of its molecular mechanism of action as well. Bolstering conclusions of previous studies of mammalian c-Jun in cell culture, my data indicate that N-terminal phosphorylation is not an on/off switch, but rather it increases Jun stability for its activity as a component of the AP-1 transcription factor. raw mutants exhibit both high levels of Jun protein and an accumulation of phosphorylated Jun (P-Jun), and my data point to a role for Raw in effecting the Jun:P-Jun ratio via mediation of Jun degradation. In deciphering the mechanism of Raw function, we are gaining significant new insights into previously unrecognized mechanisms of JNK signaling regulation. Understanding these mechanisms will be important for dissecting the etiology of developmental abnormalities and diseases, such as cancer, which hinge on the Goldilocks effect, having just the right amount of signaling at just the right time.

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12

Crompton, Douglas Ewan. „Molecular analysis of the shaking-B locus of Drosophila melanogaster“. Thesis, University of Glasgow, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309523.

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13

Abukashawa, Sumaia. „Patterns of molecular evolution at the amylase locus in Drosophila“. Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5995.

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Genes encoding the starch-degrading enzyme, alpha-amylase, are found in all major groups of animals, plants and microbes. In this thesis, amylase-coding sequences have been chosen as a model system to investigate the patterns of molecular evolution in an enzyme-coding gene. Previous phylogenetic comparisons of amylase-coding sequences have shown high levels of primary sequence conservation over long evolutionary periods. The studies described here have concentrated on the evolution of these genes within the genus Drosophila. I have studied patterns of genetic variation within populations of a single species, Drosophila melanogaster, using two techniques: (i) allozyme variation and (ii) restriction fragment length polymorphisms (RFLPs). In order to get more precise information on the intraspecific patterns of variation, I have also isolated and partially sequenced the amylase genes from a wildtype strain of D. melanogaster. This sequence was compared to the known sequences which have already been described for laboratory strains. The work was extended to interspecific comparisons by studying amylase sequences from species that were closely-related to D. melanogaster (in this case D. erecta), and also a distantly-related species (D. virilis). This involved the isolation and sequencing of the amylase gene from a D. virilis genomic library. The results revealed several interesting patterns in the evolution of: (i) the primary gene sequences (e.g., gene conversion and codon bias), (ii) gene structure (e.g., changes in intron frequency and location) and (iii) gene organization (e.g., variation in the number of gene copies). These results, concerning both short-term and long-term patterns of molecular evolution within the genus Drosophila, are discussed in the context of what is currently known about patterns of molecular evolution in general, and about the molecular evolution of amylases in particular.

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14

Carneiro, da Silva Joana Servulo Correia. „Population genetics of P transposable elements and their host species, with emphasis on Drosophila willistoni and Drosophila sturtevanti“. Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284221.

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The evolution of the P element family was studied in members of the Drosophila willistoni and Drosophila saltans species groups (subgenus Sophophora). The transmission of P elements among species, their spread within species and the strength of selective constraints, as well as the level at which they are imposed on these elements, were investigated using DNA sequence data. Particular emphasis was placed on the evolution of the canonical P element subfamily. This subfamily includes the functional P element first isolated from Drosophila melanogaster, which was termed canonical. It includes also other P elements belonging to the saltans and willistoni groups that are closely related to it. Based on the divergence among canonical elements, it was estimated that they last shared a common ancestor 3 million years ago, and that a minimum of eleven horizontal transfer events among species have taken place since then. This indicates that horizontal transfer is more important than anticipated in the transmission of P elements among species. The evolution of P elements within species was studied in detail in Drosophila sturtevanti and Drosophila willistoni. First, the population structure of these species was inferred from nuclear (alcohol dehydrogenase) and mitochondrial (part of subunits 4 and 5 of NADH dehydrogenase, and the transfer RNA gene for histidine) markers. The results suggest that only peripheral populations of D. willistoni show significant genetic differentiation. In D. sturtevanti significant population subdivision was detected among populations in the central part of the distribution, as well as between these and peripheral populations. These results were used as a reference to which P element divergence among populations could be compared. No selective constraints were detected in the evolution of canonical P elements within these two species. However, those constraints are present when elements were compared between species. It is concluded that selection is mostly effective at the time of horizontal transmission between species. Furthermore, P elements are shown to spread faster among populations than do neutral markers. This suggests that the spread of P elements within species can be achieved quickly, and surpass barriers such as moderate levels of population structuring within a species.

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15

Chicoine, Jarred. „The molecular role of Bicaudal-C in Drosophila oogenesis /“. Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102968.

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Bicaudal-C (Bic-C) encodes a KH-type RNA binding protein required maternally for anterior patterning of the Drosophila oocyte and correct migration of the centripetal follicle cells. In Drosophila, premature translation of the germ-plasm determinant Oskar in Bic-C mutant oocytes suggests a function for Bic-C in post-transcriptional gene regulation.
Purification and microarray analysis of Bic-C containing ribonucleoprotein complexes revealed that Bic-C associates with multiple transcripts encoding functionally-related components of the Wnt/Frizzled/Dishevelled signaling pathway that regulate actin dynamics, in addition to its own mRNA. Using transgenic reporter constructs, Bic-C was demonstrated to destabilize its own mRNA via cis-acting 5' UTR elements. When auto-regulation was bypassed and Bic-C was over-expressed in the female germline, premature cytoplasmic streaming was induced, disrupting axial patterning through displacement of both Gurken (Grk) and oskar. These phenotypes can also be induced by disruption of the actin cytoskeleton with pharmacological agents and are similar to those described for hypomorphic mutant alleles of orb, which encodes a CPEB-like protein that promotes polyadenylation of target mRNAs. The Bic-C overexpression phenotypes require its RNA binding activity, are substantially enhanced by mutations affecting orb and poly(A) polymerase, and are suppressed by mutations affecting the deadenylase CCR4 and its accessory protein NOT3. Co-immunoprecipitation experiments demonstrate that Bic-C associates with components of the deadenylase complex and with components of an ER-associated RNP complex that includes Me31B, PABP and Trailer-hitch. The latter complex is involved in Grk exocytosis. Accordingly, Grk secretion is defective in Bic-C mutants.
Taken together, these results support a model whereby Bic-C antagonizes Orb function by negatively regulating the expression of Orb target mRNAs, through recruitment of the deadenylase machinery, that are involved in coordinating cytoplasmic movements. Furthermore, this work identifies a novel function of Bic-C in dorsal/ventral patterning by promoting Grk secretion.

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16

Hu, Song. „The molecular genetics of the raspberry locus in Drosophila melanogaster“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ34780.pdf.

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17

McCaffrey, Ruth Anne. „Molecular and genetic characterisation of spindle-C in Drosophila melanogaster“. Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621898.

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18

O'Connell, Sinead. „Functional characterisation of the Polycomblike protein of Drosophila melanogaster“. Title page, table of contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09pho1841.pdf.

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19

Corish, Peter. „Molecular studies of non-cytotype P-M hybrid dysgenesis repression in Drosophila melanogaster“. Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624105.

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20

Lonie, Andrew. „Cloning and characterisation of the Polycomblike gene, a transacting repressor of homeotic gene expression in Drosophila“. Title page, contents and summary only, 1994. http://hdl.handle.net/2440/21504.

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Includes bibliographies.
{59} leaves : ill. ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
The Polycomblike gene of Drosophila melanogaster is required for the correct spatial expression of the homeotic genes of Antenapaedia and Bithorax Complexes. This thesis describes the isolation and molecular characterization of the Polycomblike gene.
Thesis (Ph.D.)--University of Adelaide, Dept. of Biochemistry, 1995

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21

Lavoie, Cynthia. „The molecular and biochemical characterization of proteins involved in translation initiation in Drosophila melanogaster“. Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29072.

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A preliminary analysis of translation initiation has been carried out using the model system Drosophila melanogaster. These efforts have focussed on identifying the homolog of mammalian of mammalian eIF-4F, a complex of three subunits; eIF-4E which binds the mRNA cap, eIF-4A which has ATP-dependent RNA helicase activity, and eIF-4$ gamma$, of unknown function. Attempts to clone the genes encoding subunits of eIF-4F have led to the isolation of two novel genes. A molecular screen for members of the DEAD family of RNA helicases that includes eIF-4A led to the isolation of a gene which encodes the putative homolog of a yeast protein involved in ribosome assembly. From a complementation screen for suppressors of mutants of the Saccharomyces cerevisiae cap binding subunit, was isolated a Drosophila cDNA encoding a putative ribosomal protein, RpS15a, of the 40S subunit. Further characterization of the mechanism of suppression has shown that overexpression of RpS15a stabilizes the yeast eIF-4E protein suggesting a direct interaction between eIF-4E and the ribosome. Our work has shown that unlike the mammalian system, two cap binding proteins exist in Drosophila. The molecular analysis of cDNA clones encoding Drosophila eIF-4E suggests that the proteins result from alternatively spliced mRNAs expressed from a single gene. The biochemical characterization of Drosophila eIF-4A has shown that eIF-4A is part of a complex similar in size to mammalian eIF-4F but that unlike mammals, one eIF-4A protein is produced from a single gene and is regulated by phosphorylation. Phosphorylated eIF-4A is present in oocytes and early embryos but not in later embryos. Phosphorylated eIF-4A accumulates on the 48S initiation complex suggesting that a mechanism involving the post-translational regulation of eIF-4A affects the translation of maternal mRNAs in the oocyte and early embryo.

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22

Jeffs, Pete. „The molecular evolution of the Adh gene in the Drosophila melanogaster subgroup“. Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333273.

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23

Saunders, Robert David Comrie. „Molecular analysis of a female-sterile mutation in Drosophila melanogaster“. Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/12900.

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24

Nguyen, Thuy 1973. „Identification of factors which interact with Bicaudal-D in oocyte determination“. Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20598.

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Traditional screens for female sterile mutants have revealed only two genes which when mutant, give a fully penetrant 16 nurse cell phenotype. One way to gain a better understanding of the function of these genes in oocyte determination, is to identify genes which interact with them. Using P-element mutagenesis, I have isolated one dominant suppressor and five dominant enhancers of Bicaudal-D, and begun the phenotypic and molecular characterization of three of these genes. By deficiency screening, I have identified two different loci which act as dominant enhancers of Bic-D, and eight different loci which act as dominant suppressors of Bic-D. Further work on defining the locus responsible for the strong suppression phenotype associated with one of these deficiencies, revealed betaH-spectrin to be a strong dominant suppressor of loss-of-function Bic-D alleles, and a strong dominant enhancer of Bic-D gain-of-function alleles.

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25

Rother, Katherine L. „The KH domain protein BICAUDAL-C regulates oskar expression during Drosophila mid-oogenesis“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0005/MQ44261.pdf.

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26

Paré, Chantal. „Genetic analysis of localization of a Bic-D::GFP fusion protein and identification of novel subcellular domains“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0028/MQ50851.pdf.

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27

Weston, Matthew James Dominic. „The genetic and molecular characterisation of weak localiser : a gene required for oskar mRNA localisation in Drosophila“. Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627603.

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28

Torres, Isabel Laureano. „The molecular function of Drosophila PAR-1 in the establishment of cell polarity and microtubule cytoskeleton regulation“. Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612544.

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29

Hain, Daniel. „Genetic and molecular analysis of drop out, the single homolog of the vertebrate MAST kinases in Drosophila melanogaster“. Thesis, University of Dundee, 2011. https://discovery.dundee.ac.uk/en/studentTheses/4d371f0c-df4c-41de-bc5b-3f2e8ee5d35a.

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Cellularisation is a specialised form of cytokinesis in Drosophila melanogaster. Cellularisation occurs after the first 13 syncytial cell cycles of the embryo and involves targeted insertion of membrane to form the blastoderm, which represents a polarised epithelium made out of about 6000 cells. The molecular machinery driving cellularisation is complex and not well understood. In this work a novel gene regulating this process is identified and characterised. The mutation drop out causes defects in intracellular transport, cell polarity and nuclear positioning. Previous work provided evidence that dop1 is an allele of the RNA silencing gene argonaute2 (ago2). However, results presented in this thesis showed that ago2 functions are unimpaired in dop mutant embryos using genetic and biochemical tools. Moreover genetic and molecular mapping revealed that dop mutants carry a mutation in a gene within close proximity to ago2.This work demonstrates that dop encodes the sole Drosophila homolog of the mammalian MAST (microtubule associated serine/threonine) kinase family. The molecular lesion in the dop1 allele of dop leads to an amino acid exchange in the kinase domain and results in a significant reduction of Dop protein levels. A detailed investigation of the mutant phenotype indicated that dop1 affects microtubule rigidity and Dynein-dependent microtubule associated transport. Search for possible Dop targets revealed reduced phosphorylation of the Dynein intermediate chain (DIC). DIC is a subunit of Dynein and has been shown to be involved in the binding of cargo to the Dynein complex. Therefore, a possible function for Dop might be the phosphorylation of DIC to regulate microtubule dependent transport by controlling Dynein-cargo interaction.

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30

Ragab, Anan. „Genetic and functional studies on abundant Drosophila HMGB proteins“. Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615068.

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31

Jowdy, Casey C. „The Regulation of Commissureless in the Embryonic CNS of Drosophila melanogaster“. The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1284172382.

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32

McElroy, Kyle A. „Balancing transcriptional activity in Drosophila through protein-protein interactions on chromatin“. Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493492.

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Chromatin plays a vital role in the implementation of gene expression programs. Several disparate groups of regulatory proteins alter chromatin state through post-translational modification of histone proteins, nucleosome remodeling, and higher order chromatin structure in order to affect gene expression. Several of these key groups, such as the Male-Specific Lethal complex and Polycomb Group have been well characterized in Drosophila. Yet aspects of their biology at the molecular level, such as the means by which they are faithfully targeted to regulated loci throughout the genome and the molecular mechanisms they employ to alter transcriptional state, still remain unexplained. In this dissertation I explore how identifying protein-protein interactions on chromatin reveals insights into these unanswered questions critical to chromatin biology. My results highlight the importance of balancing active and repressive chromatin states for the proper maintenance of gene expression. The Male-Specific Lethal complex is the dosage compensation complex in Drosophila, which upregulates gene expression on the male X chromosome approximately two-fold. The MSL complex catalyzes an acetyl mark which may create a uniquely permissive chromatin state to promote transcriptional elongation. A proteomic screen for MSL-interacting proteins identified UpSET, the Drosophila homolog of yeast SET3 and mammalian MLL5. Interestingly, SET3 and UpSET have been characterized to assemble into histone deacetylase complexes. I employed genetic, genomic, and proteomic techniques to assess whether UpSET plays a role in dosage compensation. UpSET appears to play a role in limiting the level of activation of the MSL complex. Surprisingly, UpSET appears to play a more important role in the maintenance of heterochromatin. The Polycomb Group is comprised of a well characterized set of developmental repressors. The PcG assembles into several multiprotein complexes to maintain the repressed state. The PcG is opposed by a group of activators known as the Trithorax group. Although the PcG and TrxG often appear to be recruited to the same genomic elements in different tissues, whether they might interact directly was not known. In a collaboration with Dr. Hyuckjoon Kang, I characterized the TrxG protein Female sterile (1) homeotic and found that it interacts specifically with PRC1. The data support a model that bivalency, a poised state observed in mammalian stem cells, may be critical, perhaps transiently, in the developing Drosophila embryo. The mechanism of coordination amongst the various PcG complexes on chromatin is not well understood. We also identified the Sex comb on midleg protein, a known member of the PcG, as a potential physical bridge between PRC1 and PRC2. In these sets of experiments, I have characterized instances of crosstalk between activating and repressing regulators which are critical for the proper maintenance of chromatin state. Perturbations of these interactions may lead to an imbalance of regulators on chromatin and aberrant transcriptional activity. These findings highlight the need for tuning gene expression state and suggest chromatin-based mechanisms by which this can be accomplished.
Biology, Molecular and Cellular

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33

Eleiche, Aliaa Abdel-Salam. „Developing an eggshell marker based on a dominant female sterile mutation for the identification of complete follicle cell clones in Drosophila melanogaster“. Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101118.

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Patterning of the body axes of the Drosophila embryo depends on maternally expressed genes, some of which function in the follicular epithelium of the developing egg chamber. Many such genes were identified in genetic screens for homozygous mutant females that produce abnormal embryos. However, mutations in zygotically required maternal effect genes are homozygous lethal, and therefore viable females cannot be recovered using this screening approach. This limitation can be overcome by generating homozygous mutant follicle cell clones in heterozygous females using a system that induces site-specific mitotic recombination events. However, to date, eggs produced from egg chambers with complete follicle cell clones cannot be directly identified. We have developed an eggshell marker for follicle cell clones using a dominant negative (DN) allele of the gene defective chorion (dec). Females with a single copy of this allele, decDN, lay collapsed eggs and are therefore sterile. Site-specific mitotic recombination events induced in females heterozygous for decDN and a mutation on the homologous chromosome arm result in homozygous mutant follicle cells that have lost decDN. Therefore, egg chambers with the entire follicular epithelium homozygous mutant generate intact eggs that can be unambiguously identified amongst otherwise collapsed eggs.

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Swan, Andrew. „Initiation of developmental asymmetry by Drosophila Bic-D, DLis-1 and microtubules“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0021/NQ55384.pdf.

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35

Ballard, Shannon L. „Regulation of Drosophila larval growth and metabolism by BMP signaling“. View abstract/electronic edition; access limited to Brown University users, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3318289.

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36

Morais, de Sá Eurico Manuel. „Molecular mechanisms for organization of cell polarity and axis formation in Drosophila“. Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608497.

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37

Sarac, Amila. „Investigating pellino function in Drosophila development“. Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100208.

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Although many of the genes and pathways involved in Drosophila embryogenesis have been thoroughly investigated, a complete understanding of the mechanisms behind these processes is still lacking. In order to gain a better perspective, the main objective of current research is to identify additional components of the signaling pathways that are crucial for normal Drosophila development.
One such developmental process is germ band retraction, which occurs in mid-embryogenesis and consists of the movement of the tail end of the germ band, or embryo proper, to its final posterior position. One of our primary objectives is to identify the signaling pathways behind this process. To this end, we investigated the 7T2 mutant, which fails to retract. This zygotic lethal mutant was originally uncovered in a screen for maternal-effect U-shaped embryonic phenotypes. Using a combination of meiotic recombination with molecularly mapped P-element insertions and complementation tests with deficiencies, we mapped the 7T2 mutant to the chromosomal region containing the gene pellino. Here, we show that both pellino mRNA and Pellino protein are missing in the 7T2 mutant tissue, indicating that 7T2 is a loss of function allele of pellino.
Further characterization of the 7T2 mutant revealed three distinct phenotypes: germ band retraction defects, twisted germ bands and head defects. Based on these observations, we propose that pellino is involved in several biological processes during early Drosophila development. Here we show that pellino is involved in the JNK pathway through genetic interaction with hemipterous, an upstream member of the JNK pathway. In addition, we provide preliminary evidence suggesting that the expression of Twist, a protein induced by the Toll pathway, is affected in the absence of pellino, suggesting a role for pellino in dorsal-ventral pattern formation.

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Martin, Sophie Geneviève. „Molecular and genetic analysis of cell polarisation, mRNA localisation and axis formation during Drosophila oogenesis“. Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620714.

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Rounding, Atkey Matthew. „Follicle cell fate determination in the Drosophila ovary : the role of the capicua gene“. Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84068.

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The gene capicua is required for the establishment of dorsal-ventral polarity in the Drosophila melanogaster ovary. Loss of capicua function in the follicle cells results in dorsalization of both the embryo and eggshell. The most prominent dorsal features of the Drosophila eggshell are the dorsal appendages. We show that loss of capicua function results in the ventral ectopic specification of dorsal appendage-producing follicle cell fate. This cell fate change is due in part to the ectopic expression of genes such as mirror and Broad-Complex in capicua mutant ovaries. When either mirror or Broad-Complex are ectopically expressed independently of loss of capicua function, they generate a phenotype similar to the capicua mutant phenotype. We propose that Capicua normally acts in the ventral follicle cells to repress the expression of genes that pattern the dorsal follicle cells. EGF receptor signaling may normally inactivate Capicua repression in the dorsal follicle cells.

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40

Mosley-Bishop, Kathleen Laverne. „Molecular genetic analysis of the Klarsicht gene in Drosophila eye development /“. Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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41

Sinadinos, Christopher. „Analysis of axonal transport and molecular chaperones during neurodegeneration in Drosophila“. Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/183403/.

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Neuronal dysfunction and cell death occurs during neurodegeneration. Animal models that express human disease genes and show neurodegenerative-like pathologies are widely used to study particular molecular systems in early neurodegenerative changes. Axonal transport (AT) is perturbed in several prevalent neurodegenerative diseases. The development of a Huntington’s Disease (HD) model in Drosophila melanogaster larvae is described, in which disease gene expression is directed to motor neurons (Chapter 2). This results in stalling and accumulation of AT vesicles in live animals and a locomotion defect after additional environmental stress. The cause of AT disruption and neuronal dysfunction in most cases of neurodegeneration is unknown, but it is associated with protein misfolding and aggregation that overrides cellular defences such as the heat shock protein (HSP) molecular chaperone system. In addition to HD, this applies to human tauopathies such as Alzheimer’s Disease (AD), which involve axonal misfolding and aggregation of tau. Increased throughput assays to test larval locomotion are developed (Chapter 3) in a Drosophila larval model of tauopathy, in which locomotion defects are detectable under normal environmental conditions. Candidate chemical modulation of this locomotion phenotype is described that targets HSP induction (Chapter 4). The chemicals used result in no detectable change in hsp70 level, lower total tau levels, and worsening of the locomotion defect phenotype. Tissue-specific elevation of hsp70 after hypoxic stress (Chapter 5) protects from acute behavioural disability and reduced survival in aged adult Drosophila expressing human tau in the nervous system. These studies indicate some therapeutic potential for HSP elevation in tau mediated pathology. Nevertheless, further work is required if chemical chaperone induction, and the roles of HSPs in axonal transport and homeostasis during chronic neurodegenerative and acute environmental stress, are to be further explored in these models

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An, Xin. „Behavioural and molecular studies of the Drosophila brain using the P[GAL4] enhancer-trap“. Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363158.

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43

Weinzierl, R. O. J. „Molecular studies of the ultrabithorax gene in Drosophila and of homologous genes in vertebrates“. Thesis, Open University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233603.

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44

Jacobs, Marc D. „The molecular evolution of the alcohol dehydrogenase gene in the Drosophila melanogaster species group“. Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338323.

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45

Mahone, Michèle. „The phenotypic and molecular characterization of the Bicaudal-C locus in Drosophila melanogaster“. Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22766.

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Bicaudal-C is a dominant maternal effect mutation which shows incomplete penetrance. Females are fertile and not all their progeny are affected. Those embryos which do not hatch show defects in their antero-posterior polarity, and give rise to bicaudal embryos which are duplicated for posterior structures. Twelve alleles of the genes have been phenotypically analysed. The penetrance of each allele has been determined and the phenotypes of embryonic defects such as mouth/head defect, bicaudal and uncellularized embryos classified and scored, in order to use this information to analyse these alleles at the cellular and molecular level. The bicaudal phenotype results from the mislocalization of the oskar and nanos RNA at the anterior end of the embryos. The gene also has a recessive phenotype which makes the females sterile. The phenotype is the result of specific defects in follicle cell migration. The alleles have been subdivided into two classes according to their phenotype: weak and strong. The gene encoding Bicaudal-C has been cloned and sequenced. It is expressed in the germline and appears to encode a member of the KH domain family of putative RNA-binding proteins.

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Masrouha, Nisrine. „Functional analysis of the Drosophila chk2 gene, loki : analysis of novel genetic interactors of Bic-D in Drosophila melanogaster“. Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80329.

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Cell cycle checkpoints are signal transduction pathways that control the order and timing of cell cycle transitions, ensuring that critical events are completed before the cell cycle proceeds. The Chk2 family of kinases plays a central role in mediating responses to DNA damage or DNA replication blocks in various organisms. My functional analysis of the Drosophila serine/threonine kinase Loki/Chk2 shows that fly chk2 monitors double-strand breaks caused by irradiation during S and G2 phases and induces cell cycle arrest in embryonic cells around cellularization.
loki is also required for the normal number of germ line cells to form in the embryo, and for normal modification of Vasa, a crucial factor in germ cell formation. However, during normal oogenesis loki expression is suppressed by orb. Another group described the involvement of Drosophila loki/chk2 in the meiotic pachytene checkpoint. Using our loki·null mutant, I obtained the opposite result: loki/chk2 does not have an essential function in this process.
The second part of my thesis deals with the question of how cells are instructed about their identity in a developing organism. (Abstract shortened by UMI.)

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47

Wesolowska, Natalia. „Modification and nuclear organization of the Drosophila melanogaster genome“. Thesis, The Johns Hopkins University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3575013.

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The success of Drosophila as a system for genetic analysis is closely linked to its amenability to genetic manipulation. Part 1 of the dissertation elucidates a novel scheme for long-range targeted manipulation of genes. We integrated an 80-kb genomic fragment at its endogenous locus, utilizing a targeted attP attachment site for the phiC31 integrase. We achieved single-copy reduction of the resulting region duplication by inducing recombinational DNA repair. We showed that this two-step scheme of integration and reduction is efficient and useful for delivering modifications. We established a vector configuration that facilitates the recovery of modifications. The integrating genomic fragment allowed for delivery of a new attachment site at 70 kb from the existing attP into a new locus, making it susceptible to targeted mutagenesis. We extrapolate that with this scheme, only 1 200 lines bearing att-sites throughout the genome would suffice to render all Drosophila genes amenable to targeted mutagenesis. Excitingly, this method should be readily applicable to other systems.

In Part 2 of the dissertation, I explored the question of telomere organization in Drosophila. Telomeres demarcate the ends of linear chromosomes to distinguish them from broken ends. In yeast, they cluster at the periphery of the nucleus establishing a compartment of silent chromatin. To bring insight into telomere organization in a higher organism, we followed EGFPlabeled Drosophila telomeric protein HOAP in vivo and found that the 16 telomeres cluster into 4-6 foci per nucleus in somatic tissues. Interestingly, HOAP signal intensity in the clusters doubles in interphase, potentially due to loading of HOAP to newly replicated telomeres. We tested several predictions about rules governing clustering. First, by inspecting mutant embryos that develop as haploids, we found that clustering is not mediated by associations between homologs. Second, by demonstrating clustering capability for a telomere of novel sequence, we eliminated DNA sequence homology and identity as important factors. Third, by marking both ends of a chromosome, we ruled out predominance of intra-chromosomal interactions. We propose that clustering is indiscriminate of sequence and is likely maintained by a yet undetermined factor.

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Barkus, Rosemarie Victoria. „The functions of Unc-104 in Drosophila motor axons“. [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3278203.

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Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2007.
Title from home page (viewed Nov. 14, 2008). Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5708. Adviser: William Saxton.

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Patarro, Thais de França. „Produtividade em espécies de Drosophila do subgrupo saltans (grupo saltans, subgênero Sophophora) : efeitos da infecção por Wolbachia em linhagens normais e introgredidas /“. São José do Rio Preto, 2015. http://hdl.handle.net/11449/127784.

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Orientador: Hermione Elly Melara de Campos Bicudo
Banca: Carlos Roberto Ceron
Banca: Marluci Monteiro Guirado
Banca: Maurício Roberto Viana Sant'Anna
Banca: Fabio de Melo Sene
Resumo: Mecanismos de isolamento reprodutivo são agentes que impedem ou diminuem a troca de genes entre duas espécies ou populações de uma mesma espécie que se encontram em processo de especiação. Esses mecanismos são compreendidos por uma serie de processos que atuam em diferentes níveis da reprodução, incluindo desde barreiras pré-zigóticas até barreiras pós-zigóticas. Nas ultimas décadas, muitos estudos têm indicado que a ausência de híbridos pode também ser promovida por interações entre microorganismos simbiontes e seus hospedeiros. Um dos principais simbiontes capazes de interagir com os insetos, levando a modificações do processo reprodutivo, são as alfaproteobactérias do gênero Wolbachia. No presente estudo, foram analisados os efeitos da infecção pela Wolbachia causados no parâmetro produtividade (número de descendentes), em intra e intercruzamentos de linhagens de Drosophila. saltans, D. prosaltans (espécies próximas pertencentes ao subgrupo saltans) e mais duas linhagens, obtidas por introgressão a partir de híbridos F1 do intercruzamento dessas duas espécies. Análises preliminares para detecção da infecção pela Wolbachia nas linhagens de Drosophila mostraram que cada uma das seis linhagens estava infectada com uma linhagem do simbionte. Os resultados quanto à produtividade foram obtidos de intra e intercruzamentos das linhagens nas condições infectadas e não infectadas A eliminação do simbionte foi realizada por tratamento com o antibiótico tetraciclina. O principal mecanismo resultante da interação simbionte-hospedeiro mencionado na literatura é chamado incompatibilidade citoplasmática (IC) e ocorre nos intercruzamentos de fêmeas não infectadas com machos infectados. Considera-se que nos machos infectados ocorrem alterações nos espermatozoides que somente os ovócitos de fêmeas infectadas podem reverter, reestabelecendo a produtividade. Os resultados obtidos, neste trabalho, sobre a...
Abstract: Reproductive isolation mechanisms are agents that prevent or decrease the exchange of genes between species or populations of the same species that are in process of speciation. These mechanisms are comprised of a series of processes operating at different levels of reproduction, ranging from pre-zygotic to post-zygotic barriers. In recent decades, studies have indicated that the absence of progeny can also be promoted by interactions of symbiont microorganisms and their hosts. Presently, the most known endosymbionts capable of interact with the insects, interfering in the reproductive process, are the alphaproteobacteria of the genus Wolbachia. In the present study, we investigated the Wolbachia effects on reproduction, focusing the parameter productivity (number of progeny) in crosses involving four strains of Drosophila saltans and D. prosaltans (close species belonging to the saltans group, Sophophora subgenus) and two introgressed strains started with F1 hybrids of these two species. Preliminary tests for screening Wolbachia showed that each of the six strains was infected with one strain of the symbiont. The results on productivity were obtained from intra and intercrosses of the strains in the conditions infected or uninfected. The elimination of Wolbachia was performed by treatment of the strains with the antibiotics tetracycline. The main mechanism resulting from the interaction symbiont-host described in the literature is called cytoplasmatic incompatibility (CI) and occurs in the intercrosses of uninfected females with infected males. It is considered that, in infected males, there are changes in the sperm that only the oocytes of infected females are able to correct, reestablishing the productivity. The present results on Wolbachia infection of the species from the saltans group were variable. In several crosses of the strains, the combinations that are sterile or almost sterile when CI effect occurs, were the most productive ...
Doutor

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50

Yang, Long 1976. „Functional analysis of the loki serinethreonine protein kinase“. Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33859.

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In cell cycle checkpoint control, the Chk2 family protein kinases play a central role in mediating the cellular responses to DNA damage or DNA replication block. However, at the beginning of this project, there was no evidence for a Drosophila homologue of Chk2. loki was identified in a screen for serine/threonine protein kinases that are expressed in the ovary. Using a phylogenetic analysis, I showed that loki is a Drosophila chk2 orthologue. To characterize the checkpoint function of loki in Drosophila development, we created a loki null mutant and generated anti-Loki antibodies. Under normal laboratory conditions, loki null mutants display no apparent defect during the whole life span. Further functional analysis revealed that loki is not required for the meiotic pachytene checkpoint, the essential DNA replication checkpoint control in syncytial embryos and the DNA damage/replication checkpoint during the larval stage. However, in postblastoderm embryos, loki is required for the DNA damage checkpoint activated by gamma irradiation. Embryos lacking loki are not able to arrest the cell cycle in response to gamma irradiation.

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Dissertationen zum Thema „Drosophila Molecular genetics“

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