ATP dependent chromatin remodeling complexes are multifactorial complexes that utilize the energy of ATP to rearrange the chromatin structure. The changes in chromatin structure lead to either increased or decreased DNA accessibility. SWI/SNF is one of such complex. The SWI/SNF complex is involved in both transcription activation and transcription repression. The ATPase subunit of SWI/SNF is called SWI2/SNF2 in yeast and Brahma, Brm, in Drosophila melanogaster. In mammals there are two paralogs of the ATPase subunit, Brm and Brg1. Recent studies have shown that the human Brm is involved in the regulation of alternative splicing. The aim of this study was to investigate the role of Brm in pre-mRNA processing. The model systems used were Chironomus tentans, well suited for in situ studies and D. melanogaster, known for its full genome information. Immunofluorescent staining of the polytene chromosome indicated that Brm protein of C. tentans, ctBrm, is associated with several gene loci including the Balbiani ring (BR) puffs. Mapping the distribution of ctBrm along the BR genes by both immuno-electron microscopy and chromatin immunoprecipitation showed that ctBrm is widely distributed along the BR genes. The results also show that a fraction of ctBrm is associated with the nascent BR pre-mRNP. Biochemical fractionation experiments confirmed the association of Brm with the RNP fractions, not only in C. tentans but also in D. melanogaster and in HeLa cells. Microarray hybridization experiments performed on S2 cells depleted of either dBrm or other SWI/SNF subunits show that Brm affects alternative splicing and 3´ end formation. These results indicated that BRM affects pre-mRNA processing as a component of SWI/SNF complexes. 1 / ATP abhängige Chromatin Remodelling Komplexe bestehen aus diversen Faktoren, welche die bei der Umsetzung von ATP freiwerdende Energie dazu nutzen, die Chromatinstruktur neu zu ordnen. Diese Veränderungen führen zu einer Zu- bzw. Abnahme in der Zugänglichkeit der DNA. Ein Beispiel dafür ist der SWI/SNF-Komplex, der sowohl in die Aktivierung als auch die Inhibierung der Transkription involviert ist. Die ATPase-Untereinheit von SWI/SNF heißt in Hefe SWI2/SNF2 und in Drosophila melanogaster Brahma (Brm). Im Gegensatz dazu besitzen Säuger zwei Paraloge der ATPase-Einheit, nämlich Brm und Brg1. Neueste Studien haben gezeigt, dass das humane Brm in der Regulation des Alternativen Spleißen beteiligt ist. Ziel dieser Arbeit ist es, die Rolle von Brm in der prä-mRNA-Prozessierung zu untersuchen. Als Versuchssysteme wurden Chironomus tentans und D. melanogaster herangezogen. Dabei eignete sich C. tentans vor allem für die in situ Studien während bei D. melanogaster das vollständig sequenzierte Genom von Vorteil war. Immunfluoreszenzfärbungen von Polytän-Chromosomen zeigen eine Assoziation von Brm von C. tentans, ctBrm; mit unterschiedlichen Genloci, einschließlich der Balbiani-Ringe (BR). Mit Hilfe von Immun-Elektronenmikroskopie und Chromatin-Immunpräzipitation (ChIP) wird die Verteilung von ctBrm entlang der BR-Gene untersucht. Dabei zeigt ctBrm eine weite Streuung. Die Ergebnisse lassen außerdem darauf schließen, dass ein Teil des ctBrm-Proteins mit naszierenden BRprä- mRNPs interagiert. Biochemische Fraktionierungs-experimente bestätigen die Assoziation von Brm mit RNP-Fraktionen nicht nur in C. tentans, sondern auch in D. melanogaster und in HeLa-Zellen. Microarray-Untersuchungen in S2-Zellen, in denen entweder dBrm oder eine andere Untereinheit von SWI/SNF depletiert war, zeigen, dass BRM als eine Komponente des SWI/SNF-Komplexes sowohl Alternatives Spleißen und die Formierung des 3´ Endes, als auch die prä-mRNA-Prozessierung beeinflusst.

1. The work described in this thesis forms part of an investigation of eukaryotic gene control. The system studied was the avian erythroid cell series since it is possible to isolate pure populations of the various cell types which have well-defined biochemical activities. These cells contain an unusual tissue - specific histone H5, which may be involved in the progressive repression of transcription observed as these cells differentiate. Although the gene controlling function of this histone must be at a very gross level, this represents a unique opportunity to investigate one facet of gene control. Probably the most sensitive technique is to assay for specific messenger RNA and gene sequences by hybridisation to an appropriate probe. The aim of this thesis was to prepare such a probe from H5 mRNA and to use it to calculate the reiteration frequency of the H5 gene in the chicken genome. 2. The cells employed were chicken reticulocytes since the only histone made in these cells is H5. Experiments were conducted which demonstrated that H5 mRNA is probably a minor species compared to globin mRNA in these cells. Furthermore, calculations indicate that the two mRNAs are probably of similar molecular weight which may complicate the isolation of H5 mRNA. As a result globin mRNA was first purified and characterised. Properties which may have proved useful in the separation of this mRNA from H5 mRNA are discussed. The globin mRNA was used to optimise techniques for the in vitro translation and identification of chicken mRNAs. This was considered necessary as mRNAs from different sources vary in the conditions required for optimal translation and it was reasoned that mRNAs from the same cell would have similar optima. 3. Total polysomal RNA was fractionated on the basis of size and poly A content. Although large amounts of globin mRNA were present, H5 mRNA could only be detected in the non - poly A containing RNA. Even in this fraction however, there was still a large excess of globin mRNA which was difficult to remove due to the demonstrated similarity of their molecular weights. 4. Since it had proved impossible to isolate the H5 mRNA by conventional techniques, immunological methods of isolating the polysomes producing H5 were investigated. Using immunoadsorbents, mRNA was prepared in small amounts which programmed the synthesis in vitro of more than 70 % H5. The yield and specificity were improved by modifying the procedure to indirect immunoprecipitation followed by oligo ( dT ) - cellulose chromatography. The resulting mRNA programmes the synthesis in vitro of more than 90 % H5. The chemical purity of the mRNA is discussed. 5. The immunologically prepared H5 mRNA was not copied into cDNA by RNA - dependent DNA - polymerase. Since this was probably due to the lack of a 3 ' poly A tract on the mRNA, an enzyme was purified and characterised which would add such a tract. The enzymically modified mRNA could then be copied into cDNA of high specific activity. 6. The H5 cDNA was characterised in terms of size and fidelity of copying. By hybridisation analysis it was demonstrated that the amount of contaminating rRNA and globin mRNA complementary sequences present in the cDNA was insignificant. The complexity of the cDNA was shown to be of the same size as the H5 mRNA and will back hybridise to this mRNA to greater than 75 %. These results are discussed to demonstrate that the cDNA is a faithful copy of H5 mRNA. The possible uses of the resulting probe are also discussed. 7. The H5 cDNA was employed to quantify the number of H5 genes in the chicken genome. The significance of this result is discussed in terms of the known reiteration and organisation of histone genes in other species, and the possible role of H5 as a gene control agent. / Thesis (Ph.D.)--Department of Biochemistry, 1975.

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Abstract Instant Messenger has become one of the most popular software among juvenile and almost can not be parted from their lives. This research would like to probe deeper into the significance of Messenger in those minority families which are marginalized by the whole society. Therefore, this research takes the minority juvenile, being less social welfare distributed, as the subject, through fundamental interviews of cases, to have an understanding of these juvenile¡¦s using Messenger and Messenger¡¦s significance in their daily lives. This research presents in two ways: one is through story narration providing ample information and clues to achieve an overall understanding; second is to analyze. Aiming at the purpose, divided into the form of relation-establishing and the motive and mechanism of interrelation to analyze the phenomenon of using Messenger. The research finds that these juvenile mostly come from a minority family, such as grand parenting. They lack parental care, get lower grades and cannot get identified by the teachers. As a result, they are depressed in real life. In addition, these juvenile use Messenger in different and distinctive ways from others. Which include : a good means of ¡§calling together¡¨ ¡V to call friends and fellows into group fight; a stealthy way of running away from home ¡V to use Messenger for preparation of running away from home; ¡§group¡¨ ¡V to communicate in an utmost speed; ¡§E generation affaire d¡¦amour¡¨ ¡V Messenger becomes a tool for developing affaire d¡¦amour; a secret means of interconnection; pressure releasing ¡V to release pressure from life through chatting with friends in Messenger; to generate self-identification through using Messenger. For these frustrated juvenile who come from minority families and can not get satisfaction from school and society, Messenger is a bigger inducement. Therefore, the society, their parents and teachers should pay more concern and care to these minority group of juvenile.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2009.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 138-149). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--University of Delaware, 2009. / Principal faculty advisor: Kirk J. Cymmek, Dept. of Biological Sciences. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 102-112). Available also in a digital version from Dissertation Abstracts.

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