Most clonal plants exhibit a modular structure at multiple levels. At the level of the organs, they are characterized by functional modules, such as, internodes, leaves, branches. At the level of the genetic individual (clone or genet), they possess independent evolutionary and physiological units (ramets). These evolutionary units arise through the widespread phenomenon of clonal reproduction, achieved in a variety of ways including rhizomes, stolons, bulbils, or lateral roots. The focus of this study was Populus tremuloides, trembling aspen, a dioecious tree that reproduces sexually by seed and asexually through lateral roots. Local forest patches in western populations of Populus tremuloides consisted largely of multiple genotypes. Multi-clonal patches were dominated by a single genotype, and in one population (Riske Creek) we found several patches (five out of 17) consisting of a single genotype. A second consequence of modularity is that during the repeated cycle of ramet birth, development and death, somatic mutations have the opportunity to occur. Eventually, the clone becomes a mosaic of mutant and non-mutant cell lineages. We found that neutral somatic mutations accumulated across 14 microsatellite loci at a rate of between 10^-6 and 10^-5 per locus per year. We suggest that neutral genetic divergence, under a star phylogeny model of clonal growth, is an alternative way to estimate clone age. Previous estimates of clone age couple the mean growth rate per year of shoots with the area covered by the clone. This assumes a positive linear relationship between clone age and clone size. We found, however, no repeatable pattern across our populations in terms of the relationship of either shape or size to the number of somatic changes. A final consequence of modularity is that during clonal growth, natural selection is relaxed for traits involving sexual function. This means that mutations deleterious to sexual function can accumulate, reducing the overall sexual fitness of a clone. We coupled neutral genetic divergence within clones with pollen fitness data to infer the rate and effect of mildly deleterious mutations. Mutations reduced relative sexual fitness in clonal aspen populations by about 0.12x10^-3 to 1.01x10^-3 per year. Furthermore, the decline in sexual function with clone age is evidence that clonal organisms are vulnerable to the effects of senescence.

No description available.

Hybrid clones of the fast-growing Eucalyptus grandis and cold-tolerant E. nitens (GN clones) have been identified by the South African Forestry Industry as being highly suitable for plantations in cold-dry marginal areas. However, one of the main problems regarding their propagation is the difficulty in rooting of cuttings, both in vitro and ex vitro. The aims of this investigation, therefore, were (1) to develop widely applicable and efficient in vitro rooting system(s) for these commercially important clones, and (2) to assess some physiological characteristics of the roots produced. Adventitious shoots (15-20 mm in length) were obtained (l0 shoots/explant) from axillary buds on Murashige and Skoog's (MS) medium containing 0.01 mg.l-1 NAA, 0.01 mg.l-1 IBA and 0.2 g.l-1 FAP. The effect of various medium components, as well as modification of culture environment on in vitro rooting, were investigated. The highest rooting frequencies in clones GN121 (75%) and GN107 (65%) were achieved on l/4 MS with additional 0.22 g.l-1 CaCl2..2H2O and 0.18 g.1-1 MgS04.7H2O, 0.1 mg.l-1 IBA, 0.1 mg.l-1 biotin, 0.1 mg.l-1 calcium pantothenate, 15 g.1-1 sucrose and 4 g.l-1 Gelrite. Best culture conditions were an initial 72-hours dark incubation followed by a 16-hours day/8-hours night photoperiod at a PPFD of 37 µmol.m-2.s-1 and 23°C day/21°C night for seven days, after which the PPFD was increased to 66 µmol.m-2.s-1 at 27°C day/21°C night for 18 days. Towards the development of a more widely applicable in vitro rooting protocol for GN clones, the use of Agrobacterium rhizogenes strains was investigated. Production of transgenic roots was observed on carrot discs and shoots from seedlings of Eucalyptus grandis and E. nitens, but not on shoots of GN clones. Therefore, a method needs to be established for the successful transfer and integration of the Ri plasmid of Agrobacterium into the hybrid plant genome for induction of transgenic roots. The quality of roots produced in vitro and from cuttings was assessed by examination of root anatomy and hydraulic characteristics. Adventitious roots were prepared for measurement of hydraulic conductivity by detopping explants, then filtered, acidified distilled water was drawn through undisturbed potted root systems under partial vacuum, causing no damage to the roots. Initial studies showed that tissue culture-derived roots exhibited a higher specific root mass hydraulic conductivity than those derived from cuttings (6.46 x 10-6 vs. 3.06 X 10-6 g.kPa-1.s-1.g-1 dry root), probably due to root architecture. Curves relating vulnerability to water potential were constructed and both types of roots showed vulnerability to cavitation at high water potentials. Differences were also observed in staining reactions (safranin and fastgreen) which might suggest differences in presence and level of secondary metabolites in these roots at the juvenile stage. Applications of the developed protocols and future research strategies are discussed. / Thesis (M.Sc.)-University of Natal, Durban, 1999.

In South Africa, Eucalyptus trees are used for many processed wood products (e.g. paper) and in the mining industry. Priorities in Eucalyptus breeding programmes include selection of varieties that are fast growers, insect and disease resistant, have appropriate wood characteristics and can grow in a wide variety of environmental conditions. Cold-tolerant cultivars of E. saligna and of E. grandis have been bred and selected in Australia and South Africa, respectively for use in cold regions of Natal Midlands and North Eastern Cape. However, the production of large numbers of such cultivars for planting out in a commercial scale is being impaired by slow growth rate, low regeneration time and poor rooting ability of cuttings from these trees. Consequently, methods of in vitro propagation of cold-tolerant clones were investigated. Axillary buds were induced and subjected to a variety of multiplication, elongation and rooting media. The optimised protocol for the production of shoots from axillary buds was: bud induction medium comprising of MS supplemented with 20 grl sucrose and 10 grl agar for 1-2 weeks, multiplication medium comprising of MS supplemented with 0.1 mgrl biotin, 0.1 mgrl calcium pantothenate, 0.2 mgrl benzyladenine phosphate, 20 grl sucrose and 3.5 grl Gelrite for 4 weeks, elongation medium for 4-6 weeks comprising of MS medium supplemented with 0.1 mgrl biotin, 0.1 mgrl calcium pantothenate, 0.35 mgr' NAA, 0.1 mgr' kinetin, 0.1 mgrl IBA, 20 grl sucrose and 3.5 gr1 Gelrite. Production of plantlets via somatic embryogenesis was also investigated but hampered because of high rates of contamination as pieces of mature leaves were used as exp1ants. Ongoing breeding programmes are aimed at obtaining hybrids of Eucalyptus that are cold tolerant. The hybrid progeny then need to be screened for cold-tolerance. However, a major problem in the selection of cold-tolerant clones is that diagnosis can only be undertaken by assessing the field performance of the genotypes under various environmental conditions. In this regard, a protocol for 1D gel electrophoresis was developed for Eucalyptus species with the view to use it for the detection of cold-tolerant stress proteins. Leaf material from both non-cold tolerant and cold-tolerant clones was used. Well-resolved gels that focused on the comparison' between protein profiles of cold-susceptible and cold-tolerant clones before and after period of cold stress were obtained. The findings of this study showed that two polypeptides, one in the lower molecular region of 14.3-20.1kD and another of a higher molecular weight in the region of 116.4-170 kD were observed after cold acclimation. These changes in polypeptide profiles were observed in cold-tolerant E. grandis x nitens (GN1) and E. saligna (AS 184, AS 196 and TS 15) but not in a non-cold tolerant species E. grandis (TAG 731). These polypeptides may have an important role in the cellular adaptation to cold temperatures. It is suggested that this method may be used as a diagnostic tool for screening cold tolerance on Eucalyptus cultivars. / Thesis (M.Sc.)-University of Natal, Durban, 1996.

The genus Eucalyptus has been planted extensively throughout the world in tropical and subtropical regions, primarily because of its economic importance and use in wood and pulp production. Due to the growing demands for timber, forestry companies need to increase the productivity of available forest land. The genetic improvement of forest trees through selection and breeding involves a lengthy process of scientifically controlled trials focused on short-term and long-term goals using breeding and production populations. This investigation focused on the use of Best Linear Prediction (BLP) and its application to: (1) the prediction of genetic gains for a breeding population and, (2) the selection of superior individuals for clonal production of E. grandis. A CSIR dataset for a 20-year-old progeny trial involving 90 open-pollinated families was obtained. Four traits, namely, diameter at breast height (DBH), stem form, splitting and density were identified for use in this investigation. Relevant data were extracted and a file termed, Dataset created. Dataset was edited, standardized and corrected for the fixed effect of replication using SAS® procedures. Precise and accurate population parameter estimates are fundamental in determining breeding strategies and thus, heritabilities of each trait and phenotypic correlations between traits in Dataset were estimated using SAS® procedures. DBH was found to have the highest heritability (0.600), followed by density (0.492). The estimated heritability for stem form was 0.401 and splitting had the lowest heritability at 0.214. A high positive phenotypic correlation of 0.83 was estimated between DBH and stem form. The phenotypic correlations between other traits were close to zero. An index provides a weighted score for individuals, which takes all relevant information into account and allows individuals or families to be chosen for breeding and production purposes. Consequently, Best Linear Prediction (BLP) of individual breeding values were calculated using MATGEN® (2003). Thereafter, BLP values were used to determine the rankings of individual trees for 15 different selection indices. In order to determine the effect of selection on the change in the population mean of a trait, the breeding population's response to selection was predicted and compared across three selection strategies, namely: (1) individual selection, (2) single-trait index selection, and (3) multiple-trait index selection. The top 8% of individuals in the breeding population were selected for and the genetic gains were predicted. It was found that the response to selection was greatest when using individual selection. Furthermore, DBH had the best selection response for all three strategies as compared to the other traits under investigation. Fifteen indices, considering different numbers and choice of traits, were compared for commonality among rankings of the top 30 individuals. Two methods, namely, (1) a rank-correlation matrix and (2) a manual assessment, were used. The commonality between indices showed that a simple index, considering two traits (DBH and density) was equally effective (93%) in identifying genetically-superior individuals as the more complex index that considered four traits. Furthermore, it was possible to select for only three traits (DBH, splitting, density) and identify the same top 30 individuals as using the index that considered four traits. The researcher's goal was to find the most desirable individuals in the population to be used for production purposes, such as clonal forestry. Consequently, various selection options, specifying certain trait requirements, were used to select superior individuals for use in production and deployment. The "commercial selection" option was the only option successful in obtaining an individual that met the required criteria for the four traits in the population of 475 individuals. The results suggested that breeders should consider large populations and only a few important traits in order to obtain a greater number of individuals suitable for mass propagation in clonal forestry. In order to further investigate the effect of population size on the number of individuals suitable for clonal forestry, a hypothetical population was generated. This was accomplished using between family and within family standard deviation values obtained from Dataset. The large hypothetical population of 1000 individuals produced twelve individuals suitable for production purposes, as opposed to only one in the real population of 475 individuals. This result further indicates that a larger population provides a greater number of individuals appropriate for use in production and deployment. This investigation successfully addressed the aims by: (1) calculating individual breeding values (BLP) and ranking individuals, (2) predicting the breeding population's response to selection, according to three strategies, for the four traits under investigation, and (3) identifying superior individuals for use in commercial clonal forestry. As the work of tree breeders is aimed at improving the growth and quality of trees by increasing the frequency of desirable genotypes in the population, further research could focus on (1) the effect of different sets of economic weightings on index rankings in a population and (2) the influence that population structure has on the optimal genetic gains obtained. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

Macrophage-conditioned medium (MacCM) inhibits the differentiation of rodent and human preadipocytes. Previous studies report that murine J774A.1-MacCM inhibits clonal expansion (early required phase of adipogenesis), including Rb phosphorylation. I hypothesized that MacCM induced alterations in cyclins and/or cyclin-dependent kinases (CDKs) were responsible for impairing Rb phosphorylation. My first objective was to assess the effect of J774A.1-MacCM on CDK4, CDK2, and their regulatory cyclins. Murine 3T3-L1 preadipocytes were differentiated with control medium or J774A.1-MacCM. Expression of cyclin D and A was inhibited by J774A.1-MacCM. Inhibition of cyclin A expression was associated with reduced differentiation-induced CDK2 activity. My second objective was to assess the expression patterns of cell cycle proteins in differentiating human abdominal subcutaneous preadipocytes, which do not undergo clonal expansion in culture. Cyclin E expression increased with differentiation. THP-1-MacCM (a human macrophage cell line) further enhanced this increase. My studies suggest MacCM leads to alterations in cyclin/CDK regulation during adipogenesis in murine and human preadipocyte models.

Staphylococcus aureus destaca-se como principal micro-organismo associado à mastite bovina contagiosa, sendo que as infecções crônicas podem ser causadas pelo crescimento bacteriano na forma de biofilmes, o que pode estar associado à persistência desta bactéria na glândula mamária e à resistência a diversos antimicrobianos. Estudos epidemiológicos empregando técnicas como a macrorestrição seguida de eletroforese em campo pulsado (PFGE) têm sido realizados, com a finalidade de identificar clones e caracterizar as infecções por S. aureus. Os objetivos deste estudo foram: avaliar a frequência de isolamento de S. aureus em amostras de leite colhidas periodicamente em um grupo de propriedades leiteiras do Vale do Taquari, RS; avaliar o perfil de suscetibilidade aos antimicrobianos dos isolados de S. aureus identificados; classificar esses isolados em grupos clonais; avaliar a distribuição e a permanência dos grupos clonais nas propriedades leiteiras ao longo do tempo, além de verificar a presença de genes relacionados à formação de biofilmes (icaA e icaD). Foram colhidas amostras de leite de todas as vacas em lactação de 21 propriedades, amostradas semestralmente durante dois anos, totalizando 1060 amostras. A presença de S. aureus nas amostras foi detectada por isolamento e a identificação foi realizada de acordo com o National Mastitis Council. Isolados confirmados foram testados, pela técnica de disco difusão em ágar, quanto à suscetibilidade frente a treze antimicrobianos. Os isolados também foram submetidos à macrorrestrição do DNA total – PFGE e posteriormente testados pela PCR para detecção dos genes icaA e icaD. Das 1060 amostras avaliadas, 395 não apresentaram crescimento bacteriano. Staphylococcus sp. coagulase negativa foram identificados em 262 amostras, seguido de 136 amostras em que identificou-se S. aureus. A frequência de isolamento de S. aureus variou de 3,45% a 70,59% nas 17 propriedades em que este agente estava presente. No teste de suscetibilidade aos antimicrobianos, a maioria (75,7%) dos 132 isolados testados apresentaram perfil de sensibilidade, sendo a resistência mais frequente à penicilina (18,2%) e ampicilina (14,4%). Em apenas 27,3% dos isolados detectou-se os genes associados à formação de biofilmes pesquisados, sendo o gene icaD o mais prevalente, seguido da presença de ambos os genes. Os 122 isolados clivados pela enzima SmaI e submetidos à PFGE foram classificados em 38 grupos clonais. Observaram-se poucos grupos clonais persistentes, pois somente seis foram descritos consecutivamente em pelo menos duas coletas. O grupo clonal 16 foi o mais prevantente, apresentando isolados em uma mesma propriedade ao longo de dois anos. Conclui-se que Staphylococcus aureus está presente na glândula mamária de bovinos em lactação em pequenas propriedades da região. Esses isolados apresentam baixa frequência de resistência aos antimicrobianos. Há uma grande variabilidade de pulsotipos entre os isolados presentes nessas propriedades, porém poucos grupos clonais persistem nas propriedades amostradas. Não foi possível associar a permanência dos grupos clonais nos rebanhos à presença dos genes icaA e icaD ou ao perfil de resistência a antimicrobianos. / Staphylococcus aureus stands out as the main microorganism associated with bovine contagious mastitis, whereas chronic infections can be caused by bacterial growth in the form of biofilms, which can be associated with the persistence of the bacteria in the mammary gland and resistance to various antibiotics. Epidemiological studies employing techniques such as macrorestriction followed by pulsed field gel electrophoresis (PFGE) have been carried out, aiming to identify clones and characterize S. aureus infections. The objectives of this study were: to assess the frequency of S. aureus isolation in milk samples collected periodically in a group of dairy farms from Taquari Valley, RS; evaluate the profile of antimicrobial susceptibility of S. aureus identified isolates; classify these isolates in clonal groups; assess the distribution and retention of clonal groups in dairy herds over time and to verify the presence of genes related to biofilm formation (icaA and icaD). Milk samples were collected from all lactating cows from 21 properties that were sampled every six months for two years, totaling 1060 samples. The presence of S. aureus in the samples was detected by isolation and the identification was performed according to National Mastitis Council. Confirmed isolates were tested for susceptibility to thirteen antimicrobial by disk diffusion technique in agar. The isolates also underwent macro-restriction of total DNA - PFGE and were subsequently tested by PCR for detection of genes icaA and icaD. Of the 1060 samples tested, 395 showed no bacterial growth. Staphylococcus sp. coagulase-negative samples were identified at 262, followed by 136 samples in which S. aureus was identified. The frequency of isolation of S. aureus ranged from 3.45% to 70.59% in 17 properties wherein this agent was present. In antimicrobial susceptibility testing, the majority (75.7%) of the 132 isolates tested showed sensitivity profile, being most frequent resistance to penicillin (18.2%) and ampicillin (14.4%). In only 27.3% of the isolates were detected genes associated with biofilm formation surveyed and icaD was the most prevalent, followed by the presence of both genes. The 122 isolates cleaved by SmaI and submitted for PFGE were classified into 38 clonal groups. There were few persistent clonal groups, because only six groups were described consecutively in at least two collections. The clonal group 16 was the most prevalent, presenting isolates at the same property over two years. Is conclusive that Staphylococcus aureus is present in the mammary gland of lactating cattle on small farms in the region. These isolates have low frequency of antimicrobial resistance. There is great variability of pulsotypes among isolates in those properties, but few clonal groups persist in the sampled properties. It was not possible to associate the permanence of clonal groups in herds to the presence of icaA and icaD or to the profile of antimicrobial resistance.

Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-27T13:30:30Z No. of bitstreams: 5 13.pdf: 1722292 bytes, checksum: 827f3e266a1f80f33a48a2f1611ace4f (MD5) license_url: 49 bytes, checksum: fd26723f8d7edacdb29e3f03465c3b03 (MD5) license_text: 20904 bytes, checksum: e09bf99e64678e4285abf3ef3e05412d (MD5) license_rdf: 22564 bytes, checksum: ff373f1ad387898ef8ba4f8bc9e37073 (MD5) license.txt: 2109 bytes, checksum: aa477231e840f304454a16eb85a9235f (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-27T14:44:51Z (GMT) No. of bitstreams: 5 13.pdf: 1722292 bytes, checksum: 827f3e266a1f80f33a48a2f1611ace4f (MD5) license_url: 49 bytes, checksum: fd26723f8d7edacdb29e3f03465c3b03 (MD5) license_text: 20904 bytes, checksum: e09bf99e64678e4285abf3ef3e05412d (MD5) license_rdf: 22564 bytes, checksum: ff373f1ad387898ef8ba4f8bc9e37073 (MD5) license.txt: 2109 bytes, checksum: aa477231e840f304454a16eb85a9235f (MD5) / Made available in DSpace on 2015-02-27T14:44:51Z (GMT). No. of bitstreams: 5 13.pdf: 1722292 bytes, checksum: 827f3e266a1f80f33a48a2f1611ace4f (MD5) license_url: 49 bytes, checksum: fd26723f8d7edacdb29e3f03465c3b03 (MD5) license_text: 20904 bytes, checksum: e09bf99e64678e4285abf3ef3e05412d (MD5) license_rdf: 22564 bytes, checksum: ff373f1ad387898ef8ba4f8bc9e37073 (MD5) license.txt: 2109 bytes, checksum: aa477231e840f304454a16eb85a9235f (MD5) Previous issue date: 2011 / Com o objetivo de investigar a toler?ncia de minicepas clonais de Eucalipto ? eleva??o gradual da salinidade do solo provocada por aplica??o de fertilizantes (aos n?veis de: S1 = 0,5; S2 = 2,5; S3 = 4,5; S4 = 6,5 e S5 = 8,5 dS m-1) e comparar os resultados obtidos com o tratamento operacional de um viveiro de produ??o, avaliou-se caracter?sticas morfol?gicas expressas em fun??o do fator ?doses salinas?, no viveiro clonal de produ??o de mudas florestais da empresa Plantar S.A., no munic?pio de Curvelo M.G. Para tanto, foram conduzidos dois experimentos no segundo semestre de 2007, o primeiro em fase de Jardim clonal, onde foram aplicados as diferentes doses de fertilizantes e extra?das as miniestacas que foram estaqueadas e deram inicio ao segundo experimento, este em fase de enraizamento em casa de vegeta??o e casa de sombra. No experimento I foram avaliados: produ??o de miniestacas, sobreviv?ncia de minicepas, evolu??o da saliniza??o do solo e da solu??o do solo, ac?mulo de nutrientes na solu??o do solo e avalia??o qu?mica das folhas das miniestacas provenientes de cada tratamento. Para a retirada da solu??o do solo, foi utilizado extratores de placa porosa sob suc??o de 80kPa, e efetuado leitura de pH e de condutividade el?trica, no ato da retirada da solu??o, e an?lises qu?micas dos teores de f?sforo, pot?ssio, c?lcio e magn?sio, seguido por an?lises qu?micas foliares de nitrog?nio, f?sforo, pot?ssio, c?lcio, magn?sio, enxofre e boro. Todas estas vari?veis, tanto no experimento I quanto no II, foram analisadas e discutidas em quatro tempos diferentes espa?ados a cada 7 dias. No experimento II, as avalia??es foram de car?ter morfol?gico, visando ? qualidade do enraizamento e a rustifica??o das mudas obtidas ao longo do processo, para tanto foi mensurado a massa seca do sistema radicular (MSR), massa seca da parte a?rea (MSPA), massa seca total (MST) e altura de plantas (H). Aos 28 dias de saliniza??o das U.E. foi constatada uma evolu??o da saliniza??o do solo com ac?mulo de alguns sais pelas plantas, causando significativa mortalidade das minicepas desde a primeira coleta de dados, a produ??o de miniestacas foi influenciada ? partir do 14? dia ap?s o in?cio da saliniza??o das unidades experimentais (U.Es.), no n?vel mais elevado de salinidade. A evolu??o da salinidade e o ac?mulo dos sais pelas plantas, n?o foram determinantes no enraizamento das estacas. ? medida que se elevou o potencial salino no substrato, em fun??o das doses salinas e do tempo, reduziu-se a sobreviv?ncia das minicepas e a produ??o de miniestacas. A taxa de sobreviv?ncia de minicepas foi significativamente comprometida, quando submetida ao potencial salino de 8,5 dS m-1, por 21 dias ininterruptos. Os valores de produ??o de miniestacas e sobreviv?ncia de minicepas, das unidades experimentais, submetidos ?s doses salinas de 0,5 dS m-1 em uma ?nica irriga??o di?ria, se equivaleram aos tratamentos operacionais com 2,0 dS m-1, com nove irriga??es di?rias. As an?lises morfol?gicas n?o se diferenciaram entre os tratamentos salinos. Os dados apresentados foram normalizados seguindo o modelo de Lilliefors e as an?lises de vari?ncia adotadas seguiram o modelo de Tukey, a 5% de probabilidade. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, [2008].

O sistema imunológico dos vertebrados é extremamente complexo, sendo responsável por proteger o organismo contra agentes causadores de doenças. Para funcionar apropriadamente, é necessário que seus componentes reconheçam de forma eficaz os elementos patógenos, a fim de neutralizá-los, e também os elementos do próprio organismo, de forma a não reagirem a estes. Estas e outras características são similares àquelas exigidas em soluções para problemas de engenharia e computação. Desta forma, os sistemas imunológicos artificiais utilizam a contraparte biológica como metáfora para o desenvolvimento de diversas ferramentas computacionais utilizadas nas mais diversas tarefas. Esta dissertação utiliza os conceitos apresentados pelos sistemas imunológicos artificiais para o desenvolvimento de um novo algoritmo de aprendizado supervisionado, baseado principalmente no mecanismo de seleção clonal. O método proposto neste trabalho, denominado clonal selection classifier with data reduction (CSCDR), utiliza uma função de aptidão com base no número de classificações corretas e incorretas apresentadas por cada anticorpo. O algoritmo tenta maximizar este valor através do processo de seleção clonal, envolvendo mutação, maturação de afinidade e seleção dos melhores indivíduos, transformando a fase de treinamento em um problema de otimização. Isto leva a anticorpos com maior representatividade e, portanto, diminui a quantidade de protótipos gerados ao final do algoritmo. Experimentos em bases de dados sintéticas e bases de dados de problemas reais, utilizadas como benchmark para problemas de aprendizagem de máquina, demonstram a eficácia do algoritmo CSCDR como técnica de classificação. Quando comparado a outros classificadores conhecidos da literatura, o CSCDR apresenta desempenho similar e, quando comparado a algoritmos baseados em instâncias, o mesmo utiliza menores quantidades de protótipos para representar os dados, mantendo o desempenho. / The vertebrate immune system is an extremely complex system, being responsible for protecting the body against disease causing agents. To function properly, it is necessary its components effectively recognize the pathogens in order to neutralize them, and also elements of the body itself, so as not to react to these. These and other features are similar to those required solutions to problems in engineering and computing. Thus, artificial immune systems use biological counterpart as a metaphor for development of several computational tools used in various tasks. This dissertation uses the concepts presented by the artificial immune systems to develop a new supervised learning algorithm, based mainly on the mechanism of clonal selection. The method proposed in this work, named clonal selection classifier with data reduction (CSCDR), uses a fitness function based on the number of correct and incorrect classifications made by each antibody. The algorithm tries to maximize this value through the clonal selection process, involving mutation, affinity maturation and selection of the best individuals, turning the training phase in an optimization problem. This leads to more representative antibodies and therefore decreases the amount of prototypes generated at the end of the algorithm. Experiments on synthetic databases and real problem databases, used as benchmark to machine learning problems, demonstrate the effectiveness of the CSCDR algorithm as a classification technique. When compared to other well known classifiers in literature, CSCDR shows similar performance and when compared to instance based algorithms, CSCDR utilizes a smaller amount of prototypes to represent the data maintaining the same performance.

Submitted by Nathália Faria da Silva (nathaliafsilva.ufv@gmail.com) on 2017-07-18T14:50:37Z No. of bitstreams: 1 texto completo.PDF: 468395 bytes, checksum: 35fdc002e0108ea6f30c11be82c91a30 (MD5) / Made available in DSpace on 2017-07-18T14:50:37Z (GMT). No. of bitstreams: 1 texto completo.PDF: 468395 bytes, checksum: 35fdc002e0108ea6f30c11be82c91a30 (MD5) Previous issue date: 2002-02-21 / Fundação de Amparo à Pesquisa do Estado de Minas Gerais / O presente estudo objetivou avaliar a influência dos subcultivos de miniestaquia seriada no rejuvenescimento de quatro clones de Eucalyptus grandis quanto: a) a capacidade de produção, vigor e sobrevivência das minicepas, bem como quanto a sobrevivência, enraizamento e vigor das miniestacas; b) à eficiência do rejuvenescimento pela miniestaquia seriada em relação à micropropagação; c) ao efeito da aplicação de diferentes dosagens do regulador de crescimento AIB (0, 500, 1.500 e 3.000 mg L -1 ) no enraizamento de miniestacas oriundas de diferentes subcultivos de miniestaquia seriada; e d) à existência de indicadores bioquímicos do potencial rizogênico de miniestacas de diferentes subcultivos de miniestaquia seriada. Para os jardins miniclonais, foram utilizadas minicepas resultantes do enraizamento sucessivo das miniestacas obtidas pela miniestaquia, sendo o jardim microclonal constituído de microcepas oriundas de mudas rejuvenescidas mediante 10 subcultivos in vitro. Para o enraizamento, as mini e microestacas permaneceram 25 dias em casa de vegetação e, para aclimatação, 10 dias em casa de sombra. A avaliação final das mudas foi realizada aos 50 dias de idade a pleno sol. De modo geral, a sobrevivência das mini e microcepas foi superior a 96% após sete coletas, tendo a produção de miniestacas variado de 5,1 a 6,3 miniestacas por minicepa por coleta e o vigor das minicepas apresentado tendência de diminuição com o maior número de subcultivos. Em geral, observou-se efeito significativo positivo da miniestaquia seriada sobre a sobrevivência, a altura e o diâmetro de colo das mudas, bem como sobre o vigor radicular em clones com menor grau de juvenilidade. Quanto à comparação da miniestaquia seriada com a micropropagação, foram observados resultados semelhantes, indicando o potencial da miniestaquia seriada como método de rejuvenescimento dos clones de Eucalyptus grandis estudados. A aplicação de AIB não resultou em aumento no enraizamento e sobrevivência das miniestacas, bem como no vigor geral das mudas originárias destas, sendo para algumas características e clones observada influência negativa das dosagens acima de 500 mg L^-1. A atividade total da enzima peroxidase tendeu a diminuir com o aumento dos subcultivos de miniestaquia seriada para os clones de menor enraizamento, não tendo havido nenhum efeito naqueles de maior enraizamento. Quanto ao teor de fenóis totais, não se observou tendência de variação em relação aos clones e subcultivos estudados. / The objective of this study was to evaluate the influence of subcultures from serial minicutting technique on the rejuvenation of four Eucalyptus grandis clones in relation to: a) production capacity, vigor and survival of the ministumps, as well as survival, rooting and vigor of the minicuts; b) the efficiency of rejuvenation by serial minicutting technique in relation to micropropagation; c) the application effect of growth regulator IBA in different dosages (0, 500, 1,500 and 3,000 mg L –1 ) on the rooting of minicuts originated from different subcultures of serial minicutting technique; and d) the existence of biochemical indicators for the rhizogenic potential in minicuts from different subcultures of serial minicutting technique. For miniclonal gardens, ministumps were used which had been brought forth by successive rooting of minicuts obtained by minicutting technique, so that the microclonal garden consisted in microstumps originated from microcutting rejuvenated by 10 subcultures in vitro. For rooting, the mini- and microcutting were kept in a greenhouse for 25 days and for acclimatization in a shade house during 10 days. The final evaluation of the minicuts was carried out when the plants were 50 days old, under full sunshine. In general, the survival of the mini- and microstumps was above 96% after seven harvests. The minicut production varied from 5.1 to 6.3 per ministump per harvest and the vigor of the ministumps presented a sinking tendency when the number of subcultures was increased. Generally, a significant positive effect of serial minicutting technique on survival, height and root collar diameter as well as on the radical vigor in clones with lower juvenility degrees was observed. In relation to the comparison of serial minicutting technique with micropropagation, similar results were observed, thus suggesting the potential of serial minicutting technique as a rejuvenation method for the studied clones in Eucalyptus grandis. The application of IBA did not result in increases for rooting or survival of the minicuts, nor in the general vigor of the minicuts they brought forth. For some characteristics and clones, negative influence of dosages above 500 mg L^-1 was observed. The total activity of the peroxidase enzyme tended to diminish with the increase of subcultures from serial minicutting technique for the clones with lower rooting, and produced no effect at all on those with higher rooting. In relation to the content of total phenols, no variation tendency was observed in relation to the studied clones and subcultures.