A cana-de-açúcar atualmente encontra-se em posição de destaque como terceira maior cultivar em área plantada no Brasil. Porém, a cultura ainda não se beneficia de tecnologias de engenharia genética no mercado brasileiro. A razão disso, está diretamente relacionada às normativas de liberação da CTNBio (RN05), a qual requer informações relevantes acerca da capacidade dispersiva de estruturas reprodutivas de organismos geneticamente modificados (OGMs) e seus mecanismos de dispersão. A fim de não comprometer o curso natural da evolução do gênero Saccharum, em que pertence a Cana-de-açúcar, a CTNBio querer também informações à cerca de seus parentes silvestres como sua área de ocorrência e seus mecanismos reprodutivos de dispersão com o objetivo de eliminar o risco de hibridação introgressão com os OGMs. Através de estudos prévios, sabe-se que a cana-de-açúcar é altamente cultivada na região nordeste e centro-sul do Brasil e que as espécies pertencentes ao gênero Saccharum selvagens como S. asperum (Nees) Steud. e S. villosum Steud. são encontradas na região Centro-Sul. Pensando nisso, a espécie S. villosum chama a atenção pelo fato ocorrer próximo à áreas de plantio de cana-de-açúcar, onde haveria risco da contaminação de transgenes. O objetivo do trabalho buscou trazer informações do ciclo reprodutivo da espécie S. villosum em comparação ao comportamento reprodutivo de cana-de-açúcar na região Centro-Sul do Brasil. Também buscou-se adquirir informações relevantes sobre a morfologia e a viabilidade dos grãos de pólen da espécie e de vários híbridos da cana-de-açúcar que ocorrem na região em questão. Assim como, informações sobre a morfologia pós-seminal da espécies S. villosum, com o objetivo de auxiliar na taxonomia do grupo. Nos estudos sobre o ciclo de vida da espécie S. villosum, foram encontrados florescimento de Abril à Julho com comportamento alógamo e de Setembro à Março com comportamento autógamo. Esses resultados auxiliam estudos de fluxo gênico entre híbridos de cana-de-açúcar e S. villosum em determinadas épocas do ano. Além disso, as características morfológicas dos grãos de pólen de S. villosum correspondem às do gênero Saccharum. As características reprodutivas dos híbridos de cana-de-açúcar na região Centro-Sul do Brasil possibilita o fluxo gênico interespecífico, por conterem grãos de pólen viáveis e formação de sementes. A sincronia do florescimento entre as espécies estudadas mostrou-se correspondentes. As características morfológicas no momento da germinação das sementes de S. villosum apresentou-se correspondentes aos integrantes do complexo Saccharum como o gênero Erianthus, esses dados irão auxiliar trabalhos futuros no reconhecimento taxonômico à nível genérico e específico. Portanto, a espécie S. villosum apresenta características reprodutivas viáveis, os quais podem resultar em cruzamento interespecífico com híbridos de cana-de-açúcar. Esses resultados irão auxiliar futuros estudos de fluxo gênico entre as espécies analisadas. / The sugarcane currently is in a prominent position as the third largest growing in planted area in Brazil. However, the culture still does not benefit from genetic engineering technologies in Brazil. The reason is directly related to the regulatory release of CTNBio (RN05), which requires relevant information about the dispersive ability of reproductive structures of genetically modified organisms (GMOs) and their dispersal mechanisms. In order not to compromise the natural course of evolution of the genus Saccharum, which belongs to sugarcane, CTNBio also want the information about their wild relatives as its range and their reproductive mechanisms of dispersion in order to eliminate the risk of hybridization introgression with GMOs. Through previous studies, it is known that sugarcane is highly cultivated in the northeast and South-Central Brazil and the wild species of the genus Saccharum as S. asperum (Nees) Steud. and S. villosum Steud. are found in the South-Central region. Thinking about it, S. villosum species draws attention because occur near areas of sugarcane plantation where there is risk of transgene contamination. The objective sought to bring information of the reproductive cycle of the species S. villosum compared to reproductive behavior of sugarcane in the South-Central region of Brazil. Also sought to acquire relevant information about the morphology and viability of pollen grains of the species and various hybrids of sugarcane that occur in the region in question. As well as information on post-seminal morphology of the species S. villosum, in order to assist the group\'s taxonomy. In studies on the life cycle of the species S. villosum, they were found flowering April to July with allogamous behavior and from September to March with autogamous behavior. These results help studies of gene flow between hybrid sugarcane and S. villosum at certain times of year. Furthermore, the morphological characteristics of the pollen grains S. villosum correspond to the genus Saccharum. The reproductive characteristics of sugarcane hybrids in South-Central region of Brazil enables interspecific gene flow, to contain viable pollen grains and seed formation. The timing of flowering among the species studied showed up correspondents. The morphological characteristics at the time of germination of S. villosum has performed corresponding to the Saccharum complex members as Erianthus, this data will assist future work on taxonomic recognition of the generic and specific level. Therefore, the species S. villosum shows viable reproductive characteristics, which may result in interspecific cross with sugarcane hybrids. These results will help future studies of gene flow between species analyzed.

Throughout existence, fungi and bacteria have long shared ecological niches and thus engage in numerous interactions to mutually enhance survival or antagonistically gain competitive advantages. Of importance to human health are those interactions that involve bacteria with the opportunistic fungi, Candida albicans. An important virulence factor of C. albicans is the ability to control morphology, which allows the transition between yeast, pseudohyphal, and hyphal phenotypes. Morphological control in C. albicans is governed by quorum sensing and the secreted autoregulatory molecule farnesol. Quorum sensing allows individual cells to sense the environment and respond as a group. Bacteria also use quorum sensing to communicate and control virulence. Despite their abundance in nature, very little is known about the interactions of C. albicans with bacteria on a genetic and molecular level. The objective of our research is to identify the genetic elements involved in C. albicans-bacterial interactions and characterize the genes that may participate in these relationships. To accomplish this, we screened a C. albicans mutant library for the ability to filament in the presence of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, where 3 typically, these three bacterial species inhibit C. albicans filamentation. We identified 836 C. albicans mutants that displayed a filamentous phenotype in the presence of bacteria. Collectively, 295 of these mutants filamented in the presence of all 3 bacterial species. Candidates were subsequently sequenced to identify the location of the mutation and the affected genetic element. CDR4, a putative ABC transporter, and ALS6, a putative adhesion, were further characterized for their specific involvement in Candida-bacterial interactions. Using a filamentation assay, cdr4 and als6 deletion strains demonstrated a decreased response to the inhibitory effects of farnesol, as well as bacterial molecules known to inhibit the production of hyphal-filaments. Additionally, the ability of cdr4 and als6 deletion strains to attach and form biofilms was significantly enhanced even in the presence of farnesol and bacterial inhibitors. The results of this study contribute to the body of knowledge involving polymicrobial interactions and these findings may lead to new antifungal targets for therapeutic interventions.

Thesis (M. A. (Translation Studies)) -- University of Limpopo, 2006 / Refer to the document

Cerebral aneurysm is a pathology of the circulatory system in the brain in which an arterial wall balloons into a blood-filled sac. If the aneurysm ruptures, stroke can occur and has a high probability of causing permanent disability or death. Aneurysm surgery carries a high rate of morbidity and mortality compared to the natural rate of aneurysm rupture, so physicians must take care in recommending surgery for an aneurysm patient. However, very little is known about the etiology of brain aneurysm rupture and what prognostics exist. The International Study for Intracranial Aneurysms suggested that large aneurysm size and posterior location are important factors in identifying high rupture risk. However, many small aneurysms and aneurysms in other portions of the circulation still rupture. Many studies have assessed morphological traits, identified from aneurysm appearance on diagnostic medical images, and found such traits to be different in aneurysms that ruptured and aneurysms that did not rupture. In fact, more than 50 such morphological indices have been introduced in the literature, and many of them redundantly quantify particular morphological characteristics. In order to demonstrate the prognostic ability of morphology as an indicator of rupture risk, however, a large longitudinal cohort study must be carried out. A study such as this is time-consuming and expensive, and each additional hypothesis that a particular morphological index is predictive of rupture risk would require increasing the study population size in order to fulfill the necessary statistical power requirements for a rigorous test. Thus, a minimal set of physically meaningful, independent metrics that fully describe the aneurysm morphology is needed. In this dissertation an automated protocol was developed to process segmented medical images and extract an exhaustive set of morphological indices that quantify all relevant morphological features. Each morphological index was then analyzed for robustness to inter-user variability and for sensitivity to the particular morphological characteristic that it was designed to quantify. A factor analysis was then performed using the most robust, sensitive metrics on a population of unruptured aneurysms from five data centers and 276 patient-specific aneurysms. The results from the factor analysis were utilized to ascertain what morphological features those metrics truly described, if there were any redundancies in definition, and the variance each morphological trait described in the population. Four underlying morphological constructs were uncovered through the factor analysis. The first factor, sac size, was highly aligned with morphological indices that measured volume and one-dimensional size measurements. Sac size described 50% of the variance in the data set. The second factor, sac irregularity, was highly aligned with morphological indices that described various aspects of irregular shape. A set of variables that all were implicated in causing irregular shape, but in reality measured sac-neck size relation, also merited inclusion of a second metric to describe the variance seen in the second factor. Sac irregularity described 20% of the variance in the data set. The third factor, sac ellipticity, aligned highly with morphological indices that described the overarching ellipticity of the aneurysm sac independent of other non-spherical characteristics. Sac ellipticity described 13% of the variance in the data set. The fourth factor, sac-vessel size relation, aligned highly with morphological indices that described the size of the aneurysm sac in relation to its parent vessel. Sac-vessel size relation described 7% of the variance in the data set. All four of these factors in combination described 91% of the variance in the data set. Five morphological indices – non-planar isolation sac volume (Vnp), Voronoi diagram core evolution irregularity index (IRRvdc), tissue stretch ratio (TSR), Voronoi diagram core evolution ellipticity index (EIvdc) and size ratio (SRang) were determined to be the key indices for describing aneurysm morphology. Finally, the proposed metrics were used to test the hypothesis that aneurysms that are chosen for untreated observation are morphologically different than those that are treated – commonly referred to as selection bias. Study population was 27 patient-specific aneurysms that were placed on untreated observation (observation group) and 27 patient specific aneurysms that were size- and location-matched but were chosen for treatment (treated group). A significant difference was found in the morphological index that measured ellipticity between the two groups, indicating that physicians already commonly select highly elliptical aneurysms for treatment. This result may give insight into physicians’ choices, and merits further investigation with a larger data set for confirmation. Additionally, because the same result was replicated in both of the metrics chosen to quantify ellipticity (for both manual and automated methods), this highlighted the use of the morphological factors in determining an minimal set of independent, robust morphological indices.

The nervous system integrates multiple sources of sensory information that ultimately controls motor neurons to generate complex movements. Motor neurons form topographically organised ‘myotopic maps’ between the nerve cord and muscles in the periphery to ensure that correct pre-motor inputs into motor dendrites are relayed through corresponding axons to the appropriate muscle groups. Therefore understanding the development and assembly of motor neuronss is crucial for understanding how animals execute various motor outputs. In adult Drosophila, ~50 motor neurons are topographically organized between each leg and the nerve cord in a highly stereotyped manner (Baek and Mann, 2009). In this thesis, I describe a novel group of transcription factors that act in a combinatorial manner to specify the projections of distinct Drosophila leg motor neurons. Our studies suggest that morphological transcription factors regulate various downstream cell-surface genes that are involved in the assembly of motor circuitry. Using in vivo live imaging I describe the developmental steps involved in Drosophila leg motor neuron axon targeting during metamorphosis and the spatial expression patterns of a novel hetero-binding Ig domain transmembrane protein family – the DIPs and Dprs (Ozkan et al., 2013) in leg neuro-musculature. I further describe a function between interacting partners DIP-alpha and Dpr10, expressed in subsets of leg motor neurons and muscles respectively, in establishing the final stereotyped terminal axon branching of corresponding motor neurons. The combinations of such interactions throughout development between leg motor neurons, not only with muscles in the periphery, but also among themselves, with leg sensory neurons and other components in the central nervous system may ultimately lead to synaptic specificity and stereotyped morphologies of Drosophila leg motor neurons.

As a comparison to the suction feeding mechanics in aquatic environments, I investigated buccal pumping in an ontogenetic series of suspension feeding Xenopus laevis tadpoles (4-18 mm snout-vent length) by examining the morphology, kinematics, fluid flow, pressure generated in the buccal cavity, and effects of viscosity manipulation. Investigation of the dimensions of the feeding apparatus of Xenopus revealed that the feeding muscles exhibited strong negative allometry, indicating that larger tadpoles had relatively smaller muscles, while the mechanical advantage of those muscles did not change across the size range examined. Buccal volume and head width also exhibited negative allometry: smaller tadpoles had relatively wider heads and larger volumes. Tadpoles were imaged during buccal pumping to obtain kinematics of jaw and hyoid movements as well as fluid velocity. Scaling patterns were inconsistent with models of geometric growth, which predict that durations of movements are proportional to body length. Only scaling of maximum hyoid distance, duration of mouth closing, and duration of hyoid elevation could not be distinguished from isometry. The only negatively allometric variable was maximum gape distance. No effect of size was found for duration of mouth opening, duration of hyoid depression, and velocity of hyoid elevation. Velocity of mouth opening, velocity of mouth closing, and velocity of hyoid depression decreased with increasing size. Fluid velocity increased with size, and is best predicted by a piston model that includes head width and hyoid depression velocity. Reynolds number increased with size and spanned two flow regimes (laminar and intermediate) ranging from 2 to over 100. Pressure was found to be greatest in the smallest tadpoles and decreased as size increased, ranging from 2 kPa to 80 kPa. The viscosity of the water was altered to explore changes in body size, independent of development (higher viscosity mimicked smaller tadpole size). Viscosity manipulations had a significant effect on the kinematics. Xenopus initially increased velocity and distance of movements as viscosity increased, but these values declined as viscosity increased further. These results suggest that abiotic factors such as fluid viscosity may set a lower size limit on suspension feeding.

This thesis mainly examines inflectional morphology of verbal paradigms in Laki, which is considered as one of the Southern varieties of Kurdish language. The association of form and content of morphological markings are viewed from a realizational angle, in which exponents (morphological forms) are associated with the morphosyntactic properties via the application of rules of exponence, appealed by paradigm functions (Stump 2001) and ordered into rule blocks (Anderson 1992). In particular, I applied the paradigm linkage theory proposed and fully developed by Stump (2002 and 2016) to account for Laki verbal paradigms. In this study, it is claimed that alignment pattern and the syntagmatic combination of some of the inflectional exponents such as agreement markers are sensitive to preterite property. Hence, I argue in favor of considering two distinct morphotactic patternings in Laki. As the result of this assumption, depending on whether the inflectional markers attach to a preterite or a non-preterite stem, we should define two separate sets of affix position in this language. Moreover, I examine Laki polyfunctional agreement markers through the consideration of the morphotactics of this language. Applying Stump's analysis (to appear) of Swahili verbal concords, I consider two distinct types of content for these agreement markers: intrinsic content, and positional content. Their positional content is what the morphotactics of the language determines.

Schizophrenia is a debilitating neurodevelopmental disorder that generates a broad symptomology. These symptoms include positive, negative, and cognitive dysfunctions, and many of these symptoms are well-replicated in animal models. One such model involves sub-chronic administration of phencyclidine (PCP) to non-human primates. The action of PCP results in the blockade of NMDA receptors, leading to glutamatergic dysfunction, which has become a basis for study of schizophrenia-like pathologies. The prefrontal cortex is an area of the brain involved in higher cognitive abilities, such as working memory and executive function. Impairments within the dorsolateral prefrontal cortex (dlPFC) have shown to mimic the cognitive symptoms of schizophrenia. The current study investigates the effect of the PCP model on the cells of the dlPFC. Layer V/VI pyramidal neurons of the dlPFC were analyzed in female juvenile, male juvenile, and male adolescent non-human primates after PCP administration. The pyramidal cells from female juvenile monkeys administered PCP did not demonstrate any statistical difference in dendrite morphology compared to age-matched controls (saline-injected). The cells from male juveniles administered PCP contained greater dendritic length in a spatial analysis of the apical arbor relative to controls. Finally, the cells from the male adolescents administered PCP demonstrated reduced dendritic length in certain values in the basal arbor compared to age-matched controls. The apical dendrites of the cells from the male adolescent subjects also had a reduced number of segments, branch points, branch tips, and dendritic length close to the soma. These findings suggest age and gender may affect the cell morphology in the dlPFC in schizophrenia-like pathologies. / acase@tulane.edu

Astrocytes display a complex, stellate morphology in the brain, commensurate with their role in regulating nearly every functional aspect of the central nervous system. Innate activation of astrocytes is a classic hallmark of neurologic injury and disorder, characterized by proliferation, process hypertrophy, and transition toward polygonal morphology. However, the extent and consistency of these morphological changes, especially in the context of distinct pathologies, remain largely unknown. Here, changes in the fine neuroanatomy of astrocytes in rhesus macaque monkeys were characterized under a variety of conditions with relevance to translational research, including autistic-like behavior, bacterial and viral infections. Brain slices from paraffin embedded tissue archives were stained for glial fibrillary acidic protein, a reactive astrocyte marker, and imaged for both grey and white matter astrocytes. These cells were 3D-reconstructed in Neurolucida software and morphometric data including soma size, process length, volume and branching were analyzed and aggregated by animal and condition. It was found that process complexity in white matter astrocytes atrophied during lentiviral infection and depressive behavior, with decreased arbor length and tip quantity observed in SIV-infected and self-injuring animals. However, the opposite was seen during a bacterial infection, with increased arbor complexity and process length seen in Brucella-infected animals. Additionally, astrocytes from animals receiving oral naltrexone treatment for self-injurious behavior displayed a reversion from atrophied cell phenotypes back to original, control morphology. Thus, astrocyte activation and subsequent remodeling is not consistent, but rather context-dependent on the specific pathology and cellular subtype, and may be a driving factor in neurocognitive disorder. / acase@tulane.edu

acase@tulane.edu