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The evolutionary relationships in Xenopus genus are intensively studied for its interspecific variability and high conservation in evolution. These characteristics possess an opportunity for comparative studying of polyploidization phenomenom on interchromosomal level and an occasion to identify the genome-forming mechanisms with cytogenetic methods. XME chromosomes (X. mellotropicalis, 2n=40) were identified via p-/q- arm length ratio in a comparison with morphometric analysis of X. epitropicalis (2n=40) chromosomes. Whole chromosome painting probes were prepared from X. tropicalis (2n=20) microdissected chromosomes and they were applied to XME metaphase spreads via optimalized Zoo-FISH. 10 chromosomal quartets were detected and one balanced non-reciprocal translocation between chromosomes XME 2 and XME 9 which must have occured in a diploid ancestor. Thus, we disprove the theory of Silurana subgenus origin via only one polyploidizatin event. Powered by TCPDF (www.tcpdf.org)

MMed (Haematology), Faculty of Health Sciences, University of the Witwatersrand / Multiple Myeloma (MM) is a malignancy of plasma cells. The incidence worldwide has been reported to be 3-4/100 000 of the population. The exact aetiology is not known, but several factors have been implicated in the aetio-pathogenesis of the disease. Chromosomal abnormalities are well documented in MM. Their detection is important, as some of the cytogenetic abnormalities such as the 13q deletion are associated with a poor prognosis. Knowledge of the prognostic factors guides the clinician with respect to the appropriate management of the patient. Prior to the use of fluorescence in situ hybridisation (FISH) as a technique for detecting cytogenetic abnormalities in MM, progress was slow in this field because of the difficulty of obtaining analysable metaphases in view of the low proliferative activity of plasma cells. FISH has significantly improved the detection rate over conventional cytogenetics. Objective: The present study set out to determine the proportion of patients with MM who have a detectable chromosome 13q deletion using conventional cytogenetic and FISH analysis. The FISH technique was specifically studied to see if the detection rate of the 13q deletion is improved compared to conventional cytogenetics. Furthermore, the cytogenetic abnormalities detected were correlated with the course of the disease, as well as other parameters of prognostic significance. vi Methods: Bone marrow aspiration specimens were obtained from thirty (30) patients with MM. Both newly and previously diagnosed patients were included. The sample size was however reduced to twenty (20) because of the need to optimise the technique and improve signal detection. Conventional cytogenetic and FISH analysis was performed using the LSI D13S319 DNA probe as the test probe, and the centromeric alpha 11 and 18 as control probes. The analysis was carried out by two observers. Results: In the current study, the detection of chromosomal aberrations was much better with FISH analysis compared to conventional cytogenetics i.e. 25% versus 5%. Of all the patients with chromosomal aberrations, 25% (5/20) had the specific deletion 13q14 (D13S319). Most of our patients (70%) presented with stage III disease. 60% of those were positive for deletion 13q14 (D13S319), i.e 3/5 patients had stage III disease. However, there was no correlation between disease stage and chromosome status, as the majority of the patients presented with advanced stage disease, irrespective of their chromosomal status. Other factors of prognostic significance such as the haemoglobin level, beta-2 microglobulin and creatinine levels were not found to correlate with the presence of the chromosomal aberration but with disease stage. Furthermore, median survival did not correlate with the presence of the chromosomal abnormality. Conclusion: FISH analysis improves the detection rate of chromosomal abnormalities in MM compared to conventional cytogenetics. The prevalence of 13q14 deletion in our patient population is lower than that reported in the

The E2A locus is involved in chromosomal translocations associated with acute lymphoblastic leukemia. The most common of these involves a translocation between chromosomes 1 and 19 (t1;19), resulting in expression of the chimeric oncoprotein E2A-PBX1. A direct interaction between transcriptional activation domain 1 (AD1) of E2A and KIX domain of the histone acetyltransferase (HAT) /co-activator CBP is required for E2A-PBX1-mediated leukemia induction in mice. This thesis examines the functional consequences of the direct, physical interaction between E2A and CBP, for both proteins. We demonstrate that the interaction between E2A and CBP/p300, as well as another HAT/co-activator, p/CAF, results in acetylation of E2A. Mutagenesis-based mapping studies identify several lysine residues as substrates for acetylation. Of particular interest, a conserved lysine (K34) located within AD1 is acetylated in vitro and in vivo. Substitution of this residue to arginine impairs transcriptional activation of a luciferase reporter while substitution to glutamine, mimicking the acetylation, restores E2A-mediated transcriptional activation. Recent studies have shown that several transcription factors can modulate the intrinsic HAT activity of CBP/p300. We were surprised to find that E2A proteins enhance acetylation of histones by CBP, in vitro and in vivo, in a KIX domain-independent manner. Acetylation of E2A is also not required for stimulation of CBP/p300 histone acetylation. It appears that E2A interacts with the other CBP domains to mediate this effect, presumably through allosteric effects. In summary, we demonstrate that acetylation of E2A plays a role in mediating the transcriptional activation activity of E2A. Furthermore, acetylation of E2A enhances its interaction with CBP/p300, at least in the presence of additional nuclear factors. We show evidence that p/CAF may mediate this effect. Enhancement of CBP/p300 HAT activity by oncogenic E2A-PBX1 proteins in vivo, suggests that some of its leukemia-promoting effects may be due to E2A-induced gain of function effects on CBP/p300. The enhanced interaction between acetylated E2A and CBP/p300, as well as the E2A-mediated stimulation of histone acetyltransferase activity might play a role in the DNA-binding-independent induction of proliferation. / Thesis (Ph.D, Pathology & Molecular Medicine) -- Queen's University, 2007-09-26 13:37:21.905

Thesis (Ph.D.)--University of Wyoming, 2008. / Title from PDF title page (viewed on June 24, 2009). Includes bibliographical references.

In light of an urgent need for improved antimicrobial diagnostics and therapeutics, understanding bacterial behaviour, and bacterial responses to treatments in particular, is one of the key objectives of modern medical research. While the molecular mode of action of antibiotics is usually well known, their effect on the cell at a "systems" level (on the regulatory networks, metabolism, etc.) is only beginning to be quantitatively understood. We address some of these response phenotypes in Escherichia coli testing different antibiotic classes and growth conditions. We study the short (< 15 s) time-scale fluctuation dynamics of fluorescently-tagged chromosomal loci and cytosolic aggregates, which report for the state of locus ”compaction” and the levels of macromolecular crowding of the cytosol, respectively. We improve the precision of those measurements developing a novel data treatment procedure and discover that sub-lethal doses of ciprofloxacin, rifampicin, and vancomycin as well as hyperosmotic shock conditions cause small but consistent changes (unique to each treatment agent) to the physical organisation of chromosomal Ori2 and Ter3 loci and the cytosol. We reveal, among other findings, strong correlations between the effects in different parts of the chromosome and between the chromosome and cytosol. In addition, we complement the marker dynamics work with single-cell level gene expression measurements during sub-lethal translation inhibition. Specifically, we compare responses to tetracycline and chloramphenicol from constitutive and ribosomal promoters in Ori3 and Ter3 chromosomal positions over long (7 h) treatment times in exponentially growing bacteria. We reveal, for the first time, the kinetics of cellular resource allocation and provide novel insights on globally regulated transcription, relevant to the three-component proteome partitioning model, gene-length dependent effects of the processivity of translation, and ”reversibility” of ribosome-binding antibiotics. In addition, we discover a strong correlation between the timing of responses from promoters in the Ori3 and Ter3 positions, and a small but consistent difference in the response magnitude between the two positions.

Made available in DSpace on 2014-06-11T19:32:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-18Bitstream added on 2014-06-13T20:03:23Z : No. of bitstreams: 1 cabraldemello_d_dr_botib.pdf: 1654082 bytes, checksum: 7e6b12e5a0a939210a7949c8a83f729c (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O mapeamento cromossômico de seqüências repetitivas de DNA tem se mostrado uma eficiente ferramenta nos estudos comparativos e evolutivos em diversos organismos. Estudos cromossômicos com besouros da subfamília Scarabaeinae têm revelado ampla variabilidade, entretanto a análise da organização cromossômica de DNAs repetitivos neste grupo é escassa e direcionada unicamente ao mapeamento do DNA ribossomal (DNAr) 18S. O presente trabalho teve como objetivo caracterizar cromossomicamente DNAs repetitivos em espécies de Scarabaeinae, utilizando bandeamentos cromossômicos e mapeamento físico cromossômico de seqüências repetitivas, incluindo famílias multigênicas de RNAr 18S, RNAr 5S e histona H3 e a fração de DNA C0t-1. Ampla variabilidade foi observada relacionada ao número/localização dos sítios de DNAr 18S, aparentemente associada a diversificação da heterocromatina. Por outro lado, os genes de RNAr 5S e histona H3, mostraram-se amplamente conservados e co-localizados em um par cromossômico, com aparente intercalação. Análises em representantes de Dichotomius revelaram conservação dos blocos de heterocromatina, entretanto com aparente compartimentalização dos mesmos. O uso da fração DNA C0t-1 confirmou o enriquecimento em DNAs repetitivos da heterocromatina, que se apresentou diversificada entre as espécies, utilizando como referência D. geminatus. Por outro lado, regiões terminais dos cromossomos apresentaram-se amplamente conservadas entre as seis espécies. Além disso, a análise da fração de DNAs repetitivos em D. geminatus indicou origem intraespecífica do cromossomo B desta espécie que possivelmente pode estar sofrendo homogeneização com seqüências encontradas no complemento A. Os resultados indicam distintos padrões de diversificação para o DNA repetitivo nos representantes de Scarabaeinae, sugerindo extensiva reorganizaçãomicrogenômica ao longo / The chromosomal mapping of repeated DNAs has been used as an efficient tool in comparative and evolutionary studies in some organism. The chromosomal studies in beetles belonging to the subfamily Scarabaeinae have revealed wide variability, although the analysis of chromosomal organization of repeated DNAs in this group is scarce and directed solely for 18S rDNA mapping. The present study aimed in chromosomal characterization of repeated DNAs in Scarabaeinae species using chromosomal banding and physical chromosome mapping of repeated sequences, including the multigene families for 18S and 5S rRNAs and H3 histone genes and the C0t-1 DNA fraction. Wide variability was observed concerning the number and location of 18S rDNA sites, apparently associated to the heterochromatin diversification. On the other hand, the 5S rRNA and H3 histone genes were widely conserved and co-located in one chromosomal pair, showing apparently interspersion. Analysis in Dichotomius representatives revealed conservation for heterochromatic blocks, although an apparent compartmentalization was observed. The use of C0t-1 DNA fraction confirmed the heterochromatin repeated DNAs enrichment, which is diversified among the species, using as reference D. geminatus. On the other hand, the terminal regions of the chromosomes were highly conserved among the six species. Moreover, the analysis of repeated DNA fraction from D. geminatus indicated intraspecific origin of a B chromosome in this species that possibly could be suffering homogenization with A complement sequences. The results indicate distinct diversification patterns for repeated DNAs in Scarabaeinae representatives, suggesting extensive microgenomic reorganization along the cladogenesis of the group