The widespread occurrence among eukaryotes of sex and of mobile DNA sequences requires an evolutionary explanation, since both appear to reduce individual fitness. Both phenomena have been hypothesized to provide fitness advantages to populations, but such explanations require rather than explain the initial establishment of mobile elements and genes for sex. Genes encoding sexuality may invade asexual populations as molecular parasites, whose success then allows mobile elements to spread as parasites of sexual genomes. The prediction that mobile elements can invade only sexual populations was tested using isogenic sexual and asexual populations of Saccharomyces cerevisiae and the retrotransposon Ty3. Active Ty3 elements more consistently invaded sexual than asexual populations. In subsequent experiments involving selection on media containing ethanol as a carbon source or $ beta$-glycerophosphate as a limiting phosphorus source, transposition by galactose-induced Ty3 elements produced none of the mutations involved in adaptation to these media, and conferred no adaptive advantage among competing populations. The mean copy numbers of two mobile elements were unchanged by long-term sexual or asexual propagation of Chlamydomonas reinhardtii populations, because transposition by these elements occurred very rarely or had no effect on fitness. Sexual and asexual S. cerevisiae populations did not differ in their adaptation to galactose media, but sexual populations maintained on glucose had higher growth rates on both media than did asexual populations maintained on glucose, implying that selection against deleterious mutations was more effective in sexual populations.

Nanopores (1 – 10 nm diameter) constructed in solid-state membranes, have shown promise as next-generation biopolymer analysis devices offering both high resolution and high throughput. One promising application of nanopores is in the analysis of nucleic acids, such as DNA. This involves translocation experiments in which DNA is placed in an ionic solution and is forced through a nanopore with the aid of an applied electric field. The modulation of ionic current through the pore during DNA translocation can then be correlated to various properties of the biopolymer such as the length. To optimally design and operate nanopore devices, it would be advantageous to develop an accurate computer simulation methodology to predict the physics of the translocation process. Hence, I have developed a physically accurate, computationally efficient simulation methodology to predict and analyze the physics of biopolymer translocation through solid-state (silicon nitride) nanopores. The overall theme of this thesis is to use this simulation methodology to thoroughly investigate important issues in the physics underlying translocation experiments and thereby determine the effects of key structural and operation parameters, such as nanopore dimensions, applied voltage, hydrodynamic interactions, solvent viscosity, and the polymer chain length. The results from these simulation studies can assist in not only proper nanopore design, but also help determine the proper experimental environments and parameters for nanopore operation.

Duchenne and Becker muscular dystrophies (DMD, BMD) are allelic X-linked diseases which affect approximately one in 3500 male newborns. They are caused by mutations in a gene positioned on the short arm of the X chromosome at Xp21. The first indication of the location of this gene was the description of rare females expressing DMD and who were found to have constitutional X;autosome translocations with an X chromosome breakpoint at this site. There are now 24 such females known worldwide. They express DMD as a consequence of preferential inactivation of the normal X chromosome. In order to contribute to the understanding of the aetiology of mutations causing DMD and the aetiology of constitutional translocations, two types of study have been performed here. Firstly, the detailed mapping of the X chromosome breakpoints of DMD-associated X;autosome translocations has been investigated. The results of this study have been compared with data on the physical distribution of mutations causing DMD in male patients. Secondly, one translocation, an X;l translocation with an autosomal breakpoint at Ip34, has been selected for more detailed investigation and the DNA sequence has been determined at the site of the rearrangement. Translocation breakpoint mapping studies were performed by somatic cell hybrid analysis. Hybrids were karyotyped and this information was used to construct a hybrid panel for the purpose of determining the autosomal localisations of anonymous DNA probes. The mapping of seven probes using this panel is described. The work described in this thesis revealed that the distribution of translocation breakpoints within the DMD gene appears to be random and may differ from the distribution of mutations in male patients. The X;l translocation whose breakpoints are cloned and sequenced was found to involve two expressed loci, one coding for dystrophin on the X chromosome and one for the leukocyte antigen related protein on chromosome 1. Sequence data revealed that a deletion of four to seven nucleotides from the X chromosome and a duplication of two to five nucleotides are associated with the translocation. The possible involvement of trinucleotides adjacent to the breakpoints, and of a LINE, a SINE and a stretch of potential Z-DNA within 1 kb of the X chromosome or the chromosome 1 breakpoint, is discussed.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 155-182).

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 7 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

CAPES / Espécies de plantas daninhas tolerantes aos herbicidas estão amplamente disseminadas em todas as regiões brasileiras. O objetivo desta pesquisa foi ampliar as informações sobre espécies/biótipos da família Rubiaceae que permitam um melhor entendimento da variação da sua tolerância ao herbicida glyphosate, dos mecanismos fisiológicos e genéticos associados à tolerância e das perdas por competição das mesmas com a cultura da soja. Populações das espécies rubiáceas Borreria latifolia e Richardia brasiliensis foram coletadas no estado do Paraná e Norte de Santa Catarina. O primeiro estudo, que avaliou a resposta a doses de glyphosate nestas espécies/populações, foi conduzido em delineamento inteiramente casualizado (DIC), em esquema bifatorial, sendo o primeiro fator as populações de cada espécie (B. latifolia e R. brasiliensis), e o segundo níveis de glyphosate (0, 74, 163, 360, 792 e 1742 g ha-1 de e.a.). Foram avaliados o controle visual aos 14 e 28 dias após aplicação (DAA), massa da parte aérea verde (MPAV) e seca (MPAS) aos 28 DAA. A investigação da absorção e translocação com glyphosate marcado radioativamente (14C) foi conduzida em DIC, com três repetições, em esquema bifatorial, sendo o primeiro fator espécies/biótipos com resposta contrastante ao glyphosate e o segundo fator sete períodos de avaliação (2, 8, 24, 48 e 72 horas após aplicação com o herbicida (HAA)). Dois estudos foram realizados em casa-de-vegetação, em DIC para quantificar ceras epicuticulares presentes na superfície das folhas das espécies rubiáceas. O primeiro foi arranjado em esquema fatorial 6 x 2, com seis biótipos, três de B. latifolia e três de R. brasiliensis (sensível, média tolerância e alta tolerância para cada espécie) submetidos aos regimes próximo a capacidade de campo do solo (CC) e próximo ao ponto de murcha permanente (PMP). Posteriormente, foi procedida a extração das ceras epicuticulares com solventes e sua quantificação por pesagem. O segundo estudo foi arranjado em fatorial 2 x 3 x 5, sendo o primeiro fator as condições hídricas do solo (CC e PMP), o segundo fator três biótipos com respostas contrastantes ao glyphosate e o terceiro fator doses do herbicida glyphosate 0,72, 163, 360 e 792 g e.a. ha-1. Foram determinados os níveis de controle das plantas aos 14 e 28 DAA, MPAV e MPAS aos 28 DAA. Um estudo determinou a variabilidade genética existente entre indivíduos e populações de espécies B. latifolia e R. brasiliensis com respostas distintas ao herbicida glyphosate (sensível e com maior tolerância) através da técnica RAPD. Dois estudos conduzidos em delineamento blocos ao acaso com quatro repetições, em esquema bifatorial para determinar a capacidade competitiva de espécies rubiáceas com a cultura da soja. O primeiro fator foi constituído pelas espécies B. latifolia e R. brasiliensis e o segundo pelas densidades 0, 2, 4, 6, 8, 10 e 12 plantas m-2. Foram avaliadas a altura de planta, área foliar e clorofila total nos estádios V6 e R5 da cultura, número de vagens por planta, número de grãos por vagem, massa de 1000 grãos e perda de rendimento de grãos. Houve variabilidade de resposta ao herbicida glyphosate entre os biótipos das espécies B. latifolia e R. brasiliensis coletados em diferentes locais do Paraná e Santa Catarina. A maior parte do herbicida absorvido ficou depositada na folha tratada, com maior translocação no biótipo sensível apenas nas avaliações efetuadas 48 e 72 HAA. A produção de ceras epicuticulares foi incrementada pelo déficit hídrico, com maior ênfase nos biótipos mais tolerantes ao glyphosate para ambas as espécies. Os marcadores RAPD foram satisfatórios na detecção de polimorfismo entre os indivíduos pertencentes a biótipos de B. latifolia e R. brasiliensis com respostas contrastantes ao herbicida glyphosate. A espécie B. latifolia foi mais competitiva com a cultura da soja, comparativamente à R. brasiliensis, provocando maiores perdas em todas as variáveis analisadas. / Herbicide tolerant weed species are widely disseminated in all Brazilian regions. The objective of this research was to increase the information about the glyphosate tolerance on species / biotypes of the family Rubiaceae, allowing a better understanding of the physiological and genetic mechanisms associated to the tolerance and the soybean losses caused due to interference. Populations of Borreria latifolia and Richardia brasiliensis were sampled in the States of Paraná and Santa Catarina. The first study, which evaluated the response to doses of glyphosate in these species / populations, was conducted in a completely randomized design (DIC) in a bifactorial scheme, with the first factor being the populations of each species (B. latifolia and R. brasiliensis), and the second the glyphosate level (0, 74, 163, 360, 792 and 1742 g ha-1 of ea). Visual control at 14 and 28 days after application (DAA), green aerial part mass (MPAV) and dry matter (MPAS) at 28 DAA were evaluated. The investigation of the absorption and translocation with radiophase (14C) -labeled glyphosate was conducted in DIC, with three replicates, in a bifactorial scheme, being the first factor species / biotypes with a glyphosate response and the second factor seven periods of evaluation (2,8 , 24, 48 and 72 hours after application with the herbicide (HAA). Two studies were carried out in greenhouse, in DIC to quantify epicuticular waxes present on the surface of the leaves of the rubiaceous species. The first one was arranged in a 6 x 2 factorial scheme, with six biotypes, three of B. latifolia and three of R. brasiliensis (sensitive, medium tolerance and high tolerance for each species) submitted to the regimes near soil field capacity (CC) and near the permanent wilting point (PMP). Subsequently, the epicuticular waxes were extracted with solvents and quantified by weighing. The second factor was arranged in factorial 2 x 3 x 5, the first factor being the soil water conditions (CC and PMP), the second factor three biotypes with contrasting responses to glyphosate and the third factor doses of the glyphosate herbicide 0, 72, 163, 360 and 792 g and ha-1. The plants control levels were determined at 14 and 28 DAA, MPAV and MPAS at 28 DAA. Another study determined the genetic variability among individuals and populations of B. latifolia and R. brasiliensis species with different responses to the herbicide glyphosate (sensitive and with greater tolerance) using the RAPD technique. Two studies conducted in a randomized complete block design with four replications, in a two - factorial scheme to determine the competitive capacity of rubiaceous species with soybean culture. The first factor consisted of the species B. latifolia and R. brasiliensis and the second by the plant density (0, 2, 4, 6, 8, 10 and 12 plants m-2). Plant height, leaf area and total chlorophyll in the V6 and R5 stages of the crop, number of pods per plant, number of grains per pod, mass of 1000 grains and loss of grain yield were evaluated. There was variability of response to glyphosate among the biotypes of B. latifolia and R. brasiliensis species collected in different locations of Paraná and Santa Catarina. Most of the absorbed herbicide was deposited on the treated leaf, with the highest translocation in the sensitive biotype only in the 48 and 72 HAA evaluations. The production of epicuticular waxes was increased by water deficit, with greater emphasis on glyphosate tolerant biotypes for both species. The RAPD markers were satisfactory in detecting polymorphism among individuals belonging to B. latifolia and R. brasiliensis biotypes with contrasting responses to glyphosate herbicide. The species B. latifolia was more competitive with the soybean crop, compared to R. brasiliensis, causing higher losses in all variables.

CAPES / Espécies de plantas daninhas tolerantes aos herbicidas estão amplamente disseminadas em todas as regiões brasileiras. O objetivo desta pesquisa foi ampliar as informações sobre espécies/biótipos da família Rubiaceae que permitam um melhor entendimento da variação da sua tolerância ao herbicida glyphosate, dos mecanismos fisiológicos e genéticos associados à tolerância e das perdas por competição das mesmas com a cultura da soja. Populações das espécies rubiáceas Borreria latifolia e Richardia brasiliensis foram coletadas no estado do Paraná e Norte de Santa Catarina. O primeiro estudo, que avaliou a resposta a doses de glyphosate nestas espécies/populações, foi conduzido em delineamento inteiramente casualizado (DIC), em esquema bifatorial, sendo o primeiro fator as populações de cada espécie (B. latifolia e R. brasiliensis), e o segundo níveis de glyphosate (0, 74, 163, 360, 792 e 1742 g ha-1 de e.a.). Foram avaliados o controle visual aos 14 e 28 dias após aplicação (DAA), massa da parte aérea verde (MPAV) e seca (MPAS) aos 28 DAA. A investigação da absorção e translocação com glyphosate marcado radioativamente (14C) foi conduzida em DIC, com três repetições, em esquema bifatorial, sendo o primeiro fator espécies/biótipos com resposta contrastante ao glyphosate e o segundo fator sete períodos de avaliação (2, 8, 24, 48 e 72 horas após aplicação com o herbicida (HAA)). Dois estudos foram realizados em casa-de-vegetação, em DIC para quantificar ceras epicuticulares presentes na superfície das folhas das espécies rubiáceas. O primeiro foi arranjado em esquema fatorial 6 x 2, com seis biótipos, três de B. latifolia e três de R. brasiliensis (sensível, média tolerância e alta tolerância para cada espécie) submetidos aos regimes próximo a capacidade de campo do solo (CC) e próximo ao ponto de murcha permanente (PMP). Posteriormente, foi procedida a extração das ceras epicuticulares com solventes e sua quantificação por pesagem. O segundo estudo foi arranjado em fatorial 2 x 3 x 5, sendo o primeiro fator as condições hídricas do solo (CC e PMP), o segundo fator três biótipos com respostas contrastantes ao glyphosate e o terceiro fator doses do herbicida glyphosate 0,72, 163, 360 e 792 g e.a. ha-1. Foram determinados os níveis de controle das plantas aos 14 e 28 DAA, MPAV e MPAS aos 28 DAA. Um estudo determinou a variabilidade genética existente entre indivíduos e populações de espécies B. latifolia e R. brasiliensis com respostas distintas ao herbicida glyphosate (sensível e com maior tolerância) através da técnica RAPD. Dois estudos conduzidos em delineamento blocos ao acaso com quatro repetições, em esquema bifatorial para determinar a capacidade competitiva de espécies rubiáceas com a cultura da soja. O primeiro fator foi constituído pelas espécies B. latifolia e R. brasiliensis e o segundo pelas densidades 0, 2, 4, 6, 8, 10 e 12 plantas m-2. Foram avaliadas a altura de planta, área foliar e clorofila total nos estádios V6 e R5 da cultura, número de vagens por planta, número de grãos por vagem, massa de 1000 grãos e perda de rendimento de grãos. Houve variabilidade de resposta ao herbicida glyphosate entre os biótipos das espécies B. latifolia e R. brasiliensis coletados em diferentes locais do Paraná e Santa Catarina. A maior parte do herbicida absorvido ficou depositada na folha tratada, com maior translocação no biótipo sensível apenas nas avaliações efetuadas 48 e 72 HAA. A produção de ceras epicuticulares foi incrementada pelo déficit hídrico, com maior ênfase nos biótipos mais tolerantes ao glyphosate para ambas as espécies. Os marcadores RAPD foram satisfatórios na detecção de polimorfismo entre os indivíduos pertencentes a biótipos de B. latifolia e R. brasiliensis com respostas contrastantes ao herbicida glyphosate. A espécie B. latifolia foi mais competitiva com a cultura da soja, comparativamente à R. brasiliensis, provocando maiores perdas em todas as variáveis analisadas. / Herbicide tolerant weed species are widely disseminated in all Brazilian regions. The objective of this research was to increase the information about the glyphosate tolerance on species / biotypes of the family Rubiaceae, allowing a better understanding of the physiological and genetic mechanisms associated to the tolerance and the soybean losses caused due to interference. Populations of Borreria latifolia and Richardia brasiliensis were sampled in the States of Paraná and Santa Catarina. The first study, which evaluated the response to doses of glyphosate in these species / populations, was conducted in a completely randomized design (DIC) in a bifactorial scheme, with the first factor being the populations of each species (B. latifolia and R. brasiliensis), and the second the glyphosate level (0, 74, 163, 360, 792 and 1742 g ha-1 of ea). Visual control at 14 and 28 days after application (DAA), green aerial part mass (MPAV) and dry matter (MPAS) at 28 DAA were evaluated. The investigation of the absorption and translocation with radiophase (14C) -labeled glyphosate was conducted in DIC, with three replicates, in a bifactorial scheme, being the first factor species / biotypes with a glyphosate response and the second factor seven periods of evaluation (2,8 , 24, 48 and 72 hours after application with the herbicide (HAA). Two studies were carried out in greenhouse, in DIC to quantify epicuticular waxes present on the surface of the leaves of the rubiaceous species. The first one was arranged in a 6 x 2 factorial scheme, with six biotypes, three of B. latifolia and three of R. brasiliensis (sensitive, medium tolerance and high tolerance for each species) submitted to the regimes near soil field capacity (CC) and near the permanent wilting point (PMP). Subsequently, the epicuticular waxes were extracted with solvents and quantified by weighing. The second factor was arranged in factorial 2 x 3 x 5, the first factor being the soil water conditions (CC and PMP), the second factor three biotypes with contrasting responses to glyphosate and the third factor doses of the glyphosate herbicide 0, 72, 163, 360 and 792 g and ha-1. The plants control levels were determined at 14 and 28 DAA, MPAV and MPAS at 28 DAA. Another study determined the genetic variability among individuals and populations of B. latifolia and R. brasiliensis species with different responses to the herbicide glyphosate (sensitive and with greater tolerance) using the RAPD technique. Two studies conducted in a randomized complete block design with four replications, in a two - factorial scheme to determine the competitive capacity of rubiaceous species with soybean culture. The first factor consisted of the species B. latifolia and R. brasiliensis and the second by the plant density (0, 2, 4, 6, 8, 10 and 12 plants m-2). Plant height, leaf area and total chlorophyll in the V6 and R5 stages of the crop, number of pods per plant, number of grains per pod, mass of 1000 grains and loss of grain yield were evaluated. There was variability of response to glyphosate among the biotypes of B. latifolia and R. brasiliensis species collected in different locations of Paraná and Santa Catarina. Most of the absorbed herbicide was deposited on the treated leaf, with the highest translocation in the sensitive biotype only in the 48 and 72 HAA evaluations. The production of epicuticular waxes was increased by water deficit, with greater emphasis on glyphosate tolerant biotypes for both species. The RAPD markers were satisfactory in detecting polymorphism among individuals belonging to B. latifolia and R. brasiliensis biotypes with contrasting responses to glyphosate herbicide. The species B. latifolia was more competitive with the soybean crop, compared to R. brasiliensis, causing higher losses in all variables.

Translocation of a 17.1 kilobase region of the OCT plasmid encoding mercury resistance (mer) in Pseudomonas putida was shown to occur in a recombination-deficient host with plasmid PP1 serving as a recipient replicon. The frequency of transposition in Pseudomonas was estimated at 10^3 -10 -^2, but undetectable in Escherichia soli. ' DNA comprising all of mr as well as subregions there of were cloned and subjected to DNA sequence analysis. Like other transposons, mer was found to contain inverted repeat sequences at its termini. These were similar to, but not identical to the inverted repeat structures found in the prototypical mercury resistance transposon Tn501 from E. aeruginosa.

Thesis (PhD (Botany and Zoology))--University of Stellenbosch, 2008. / The Bathyergidae are subterranean rodents endemic to Africa south of the Sahara. They are characterised by divergent diploid numbers that range from 2n=40 in Fukomys mechowi to 2n=78 in F. damarensis. In spite of this variation there is limited understanding of the events that shaped the extant karyotypes and in an attempt to address this, and to shed light on the mode and tempo of chromosomal evolution in the African mole-rats, a detailed analysis of both the autosomal and sex chromosome components of the genome was undertaken. In addition to G- and Cbanding, Heterocephalus glaber (2n=60) flow-sorted painting probes were used to conduct cross-species chromosome painting among bathyergids. This allowed the detection of a balanced sex chromosome-autosome translocation in F. mechowi that involved a complex series of rearrangements requiring fractionation of four H. glaber autosomes and the subsequent translocation of segments to sex chromosomes and to the autosomal partners. The fixation of this rare rearrangement has probably been favoured by the presence of an intercalary heterochromatic block (IHB) that was detected at the boundary with the translocated autosomal segment. Male meiosis in Cryptomys, the Fukomys sister clade, was investigated by immunostaining of the SCP1 and SCP3 proteins involved in the formation of the synaptonemal complex. This allowed confirmation of a Y-autosome translocation that is shared by C. hottentotus subspecies. We discuss reduced recombination between Y and X2 that seems to be heterochromatin dependent in the C hottentotus lineage, and the implications this holds for the evolution of a meiotic sex chromosome chain such as has been observed in platypus. By extending cross-species chromosome painting to Bathyergus janetta, F. damarensis, F. darlingi and Heliophobius argenteocinereus, homologous chromosomal regions across a total of 11 species/subspecies and an outgroup were examined using cladistic and bioinformatics approaches. The results show that Bathyergus, Georychus and Cryptomys are karyotypically highly conserved in comparison to Heterocephalus, Heliophobius and Fukomys. Fukomys in particular is characterised by a large number of rearrangements that contrast sharply with the conservative Cryptomys. The occurrence and fixation of rearrangements in these species has probably been facilitated by vicariance in combination with life history traits that are particular to these mammals.