No description available.

The formation of the Human Genome Organization, nicknamed HUGO, in 1988 was a response by scientists to the increasing number of programs designed to examine in detail human genetic material that were developing worldwide in the mid 1980s and the perceived need for initiating international collaboration among the genomic researchers. Despite the expectations of its founders, the Human Genome Organization has not attained immediate acceptance either inside or outside the scientific community, struggling since its inception to gain credibility. Although the organization has been successful as well as unsuccessful in its efforts to initiate international collaboration, there has been little or no analysis of the underlying reasons for these outcomes. This study examines the collaborative activities of the organization, which are new to the biological community in terms of kind and scale, and finds two conditions to be influential in the outcome of the organization’s efforts: 1) the prior existence of a model for the type of collaboration attempted; and 2) the existence or creation of a financial or political incentive to accept a new collaborative activity. / Master of Science

published_or_final_version / Microbiology / Doctoral / Doctor of Philosophy

No description available.

No description available.

No description available.

<p>Alternative RNA splicing is one of the leading mechanisms contributing towards transcript and protein diversity. Several alternative splicing surveys have confirmed the frequent occurrence of exon skipping in human genes. However, the occurrence of exon skipping in mouse genes has not yet been extensively examined. Recent improvements in mouse genome sequencing have permitted the current study to explore the occurrence of exon skipping in mouse genes orthologous to human genes on chromosome 22. A low number (5/72 multi-exon genes) of mouse exon-skipped genes were captured through alignments of mouse ESTs to mouse genomic contigs. Exon-skipping events in two mouse exon-skipped genes (GNB1L, SMARCB1) appear to affect biological processes such as electron and protein transport. All mouse, skipped exons were observed to have ubiquitous tissue expression. Comparison of our mouse exon-skipping events to previously detected human exon-skipping events on chromosome 22 by Hide et al.2001, has revealed that mouse and human exon-skipping events were never observed together within an orthologous gene-pair. Although the transcript identity between mouse and human orthologous transcripts were high (greater than 80% sequence identity), the exon order in these gene-pairs may be different between mouse and human orthologous genes.<br /> <br /> Main factors contributing towards the low detection of mouse exon-skipping events include the lack of mouse transcripts matching to mouse genomic sequences and the under-prediction of mouse exons. These factors resulted in a large number (112/269) of mouse transcripts lacking matches to mouse genomic contigs and nearly half (12/25) of the mouse multi-exon genes, which have matching Ensembl transcript identifiers, have under-predicted exons. The low frequency of mouse exon skipping on chromosome 22 cannot be extrapolated to represent a genome-wide estimate due to the small number of observed mouse exon-skipping events. However, when compared to a higher estimate (52/347) of exon skipping in human genes for chromosome 22 produced under similar conditions by Hide et al.2001, it is possible that our mouse exon-skipping frequency may be lower than the human frequency. Our hypothesis contradicts with a previous study by Brett et al.2002, in which the authors claim that mouse and human alternative splicing is comparable. Our conclusion that the mouse exon-skipping frequency may be lower than the human estimate remains to be tested with a larger mouse multi-exon gene set. However, the mouse exon-skipping frequency may represent the highest estimate that can be obtained given that the current number (87) of mouse genes orthologous to chromosome 22 in Ensembl (v1 30th Jan. 2002) does not deviate significantly from our total number (72) of mouse multi-exon genes. The quality of the current mouse genomic data is higher than the one utilized in this study. The capture of mouse exon-skipping events may increase as the quality and quantity of mouse genomic and transcript sequences improves.</p>

Orientador: Celso Luis Marino / Coorientador: Douglas Silva Domingues / Banca: Ivan de Godoy Maia / Banca: Marie-Anne Van Sluys / Banca: Maria Lucia Carneiro Vieira / Banca: Nathalia de Setta Costa / Resumo: Os retrotransposons com LTR (long terminal repeats) (LTR-RTEs) são os componentes mais abundantes nos genomas vegetais. Eles são divididos em duas superfamílias, Copia e Gypsy, de acordo com a ordem dos domínios internos e com a similaridade das sequências. São conhecidos pela sua natureza ubíqua e plasticidade, o que os leva a serem explorados como ferramentas para o desenvolvimento de marcadores moleculares, utilizando-se assim o padrão de inserção dos LTR-RTEs para geraçã o de polimorfismos. As famílias de LTR-RTEs apresentam número de cópias variável dentro de um mesmo genoma, mas a amplificação de poucas famílias pode contribuir com grandes diferenças de tamanho entre genomas próximos. Em plantas do gênero Eucalyptus existem poucos estudos relacionados aos LTR-RTEs, que geralmente limitam-se a análises em bancos de dados privados. Este trabalho tem como objetivo a caracterização de LTR-RTEs transcricionalmente ativos pertencentes as superfamílias Copia e Gypsy, encontrados no genoma de eucalipto. A partir de análises preliminares de bioinformática, um total de nove famílias de LTR-RTEs foram identificadas; os elementos da superfamília Copia foram classificadas em cinco linhagens e elementos da superfamília Gypsy foram divididos em três linhagens. As análises in silico no genoma draft de Eucalyptus grandis identificaram que as famílias caracterizadas possuem entre 38 e 290 cópias. Os LTR-RTEs foram utilizados para o desenvolvimento de marcadores moleculares IRAP, REMAP e RBIP, que foram avaliados em cinco espécies de eucalipto. Dezesseis primers IRAP foram avaliados e um total de 1521 fragmentos foram gerados, com 321 fragmentos polimórficos, em um intervalo de 250 a 2500 bp e uma média de 19,01 fragmentos amplificados por primer. Vinte e oito combinações de primers REMAP foram avaliadas e geraram 1910 fragmentos, dos quais 492 são polimórficos, em um intervalo de 200 a 1250 bp, com uma média de ... / Abstract: Long Terminal Repeat Retrotransposons (LTR-RTEs) are the most abundant component of plant genomes. They are divided into two superfamilies, Copia and Gypsy, based on coding domain order and sequence similarity. As dynamic and ubiquitous entities in plant genomes, marker systems based in LTR-RTEs were developed to exploit LTR-RTEs insertion pattern polymorphism. In most angiosperm genomes, LTR-RTEs families have a wide range of copy number, but the amplification of a few families individually contribute to a large fraction of the genome. LTR-RTEs were scarcely studied in the Eucalyptus genus, with most findings derived from global analyses of private genomic databases. The aim of this work is to characterize transcriptionally active Copia and Gypsy LTR-RTEs in Eucalyptus sp genomes. After preliminary bioinformatics analyses, a total of 9 full-length LTR-RTEs families were classified into five Copia and three Gypsy lineages. BLAT analysis in Eucalyptus grandis draft genome identified that these elements have between 38 and 290 copies. These LTR-RTEs were used to develop IRAP, REMAP and RBIP markers, which were evaluated in five Eucalyptus species (Eucalyptus brassiana, E. grandis, Eucalyptus saligna, Eucalyptus tereticornis and Eucalyptus urophylla). Sixteen IRAP primers produced 321 polymorphic fragments from a total of 1521 bands, ranging from 250 to 2500 bp, with an average of 19.01 bands amplified per IRAP primer. Twenty-eight REMAP primer combinations produced 1910 bands. 492 of them were polymorphic, ranging from 200 to 1250 bp. An average of 13.64 REMAP bands was scored per primer. Our results showed that the genetic similarity assessed by both IRAP and REMAP markers did not reflect molecular phylogenetic analysis. Nonetheless, these markers are useful for the assessment of genetic diversity the individual level and population analysis. We developed RBIP markers for three site-specific ... / Doutor

O trabalho descreve um método para isolamento de núcleos morfologicamente intacto e fisiologicamente ativos, além da caracterização parcial do DNA de Acanthamoeba castellanii (linhagem Neff). O DNA celular total de trofozoitos contém quatro famílias com diferentes velocidades de renaturação. A fração com renaturação mais lenta (DNA \"único\"), corresponde ao DNA nuclear (86% do genoma) e apresenta características cinéticas compatíveis com uma complexidade de sequência igual a 1,46x1011 daltons. O DNA reiterado (14% do genoma), compreende três famílias de sequências de nucleotídeos, denominadas \"rápidas\", \"intermediária\" e \"lenta\", com complexidade cinética respectivamente igual a 1,5x106; 2,1x10<SUP.7 e 2,6x108 daltons, presentes em aproximadamente 3x103, 3x102 e 50 cópias. As famílias de DNA reiterado têm localização predominantemente citoplasmática, sendo que as famílias \"intermediárias\" e \"lentas\" fazem parte do genoma mitocondrial. O comportamento cinético heterogêneo do DNA mitocondrial e sua complexidade assemelham-se aos dados existentes para outros microrganismos eucariotos. A constatação de uma espécie de DNA extramitocondrial pode ser relacionada com a descrição anterior de corpúsculos citoplasmáticos contendo DNA ou com a extrusão de cromatina para o citoplasma, verificada no início do encistamento. O DNA de trofozoitos também foi caracterizado quanto ao padrão de sedimentação em gradientes de densidade, desnaturação térmica e composição de bases. O DNA celular total apresenta dois componentes em gradientes de CsCl, caracterizados por densidade de flutuação iguais a 1,717 g/cm3 (Componente maior) e 1,692 g/cm3 (componente menor). O perfil de fusão do DNA mitocondrial sugere heterogeneidade de composição de bases. / Abstract not available.

Many factors may explain why certain transposable elements (TEs) spread in some species and not others. On the one hand, they include processes that affect the rate of transposition, such as differences in the regulation of expression; on the other hand, they include characteristics of a genome that affect the consequences of transposition. In particular genome size may have an effect: a genome that is large due to non-essential repetitive DNA may be permissive for TE movement, as insertion events are less likely to be deleterious. Genome size may also help explain the pattern of TE distribution between species of mosquitoes, including the important vectors of arboviruses, Aedes aegypti and Culex pipiens sensu lato. These species have genomes 3- 5 times larger than a third genus, the Anopheles mosquitoes, which includes the malaria vectors. While all mosquitoes carry a diverse range of TEs, only culicines have the super abundant retroposon, Juan which can contribute up to 3% of the genome. The genome sequences of various insect species were compared and the mosquitoes show a significant trend of increase in genome size, which can be attributed to the increase in retroposon sequences. Two variants of Juan are reported, and new information is added regarding these elements. Previous publication of these elements contained errors in their sequences. A unique triple repeat of a cysteine rich region with a CCHC motif is present in the open reading frame. This sequence is a zinc-knuckle domain, important for the replication mechanism of these elements. In comparison, a third recently active but very low copy number retroposon, termed Pip1, is also described. The results show that Pip1 is related to the Juan elements and also possess the triple CCHC motif. The PCR results also supports previous findings of polymorphism in insertion sites of this element, suggesting that Pip1 was active after the establishment of the different strains. Pip1 copies can be grouped into three distinct groups based on nucleotide differences. Pip1 could also be using an alternative start codon to initiate transcription. Full length intact copies of the three TEs in this study were been cloned into a germline transformation vector based on piggyBac and used for germline transformation in Drosophila melanogaster. Drosophila melanogaster has no Juan or Pip1 elements and an even smaller genome than anophelines mosquitoes, so insertion events from unregulated TE movement should be more detectable. We found that the elements have been successfully introduced into the Drosophila lines. The lines were inbred to obtain a homozygous population. A range of transformed lines were monitored. No effects of hybrid dysgenesis was found. Flies with black spotted eyes were identified in a Pip1 line but this phenotype was not heritable. Whole genome sequencing was carried out on the flies using next generation sequencing (NGS) technology. Retroposon sequences was detected at a high frequency. Insertion junctions were not detected but this result does not eliminate the possibility that a junction is present but the sequencing was not sensitive enough. A possible explanation is the retroposon is present as extrachromosomal plasmid DNA.