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O DNA repetitivo constitui uma fração considerável do genoma de muitos organismos eucarióticos. Composto tanto por sequências funcionais, como os genes ribossômicos, quanto não codificantes, como é o caso dos elementos transponíveis, mini/microssatélites e o DNA satélite, essa porção do genoma tem sido amplamente utilizada como objeto de estudo, uma vez que sequências repetitivas podem estar associadas, por exemplo, a processos de diferenciação sexual. Esses estudos têm auxiliado tanto na melhor compreensão da dinâmica dessas regiões cromossômicas, como salientado a importância, a conservação e a evolução da porção repetitiva no genoma. O gênero Eigenmannia (Gymnotiformes, Sternopygidae) compreende espécies crípticas do ponto de vista morfológico que exibem variação no número cromossômico e podem apresentar sistemas sexuais XY ou ZW nos quais os elementos do par sexual diferem pela presença de blocos heterocromáticos maiores do que os encontrados em cromossomos autossomos, ou sistemas múltiplos envolvendo translocação Y-autossomo. O presente trabalho tem por objetivos o estudo sobre do gene Citocromo Oxidase I (COI), de forma a verificar a capacidade discriminatória desse gene mitocondrial e sugerir possíveis espécies dos então cariomorfos do gênero Eigenmannia no estado de São Paulo, continuidade do estudo do DNA repetitivo no gênero Eigenmannia, tanto de regiões funcionais do genoma, no caso o gene ribossômico 5S, bem como de elementos transponíveis, permitindo assim uma melhor compreensão sobre a distribuição, conservação nos cariomorfos e verificar sua eventual participação no processo de diferenciação não só de cromossomos sexuais, mas também na evolução cariotípica do grupo. Os resultados obtidos com o gene COI, assim como aqueles obtidos pelo gene ribossômico 5S evidenciam distâncias genéticas consistentes com a hipótese de que os cinco cariomorfos possam ser considerados como espécies distintas. Além disso, a hibridação in situ do gene ribossômico 5S forneceu uma nova evidência para a fusão cromossômica que deu origem ao cromossomo sexual Y, já descrita na literatura, enquanto que a hibridação de sequências teloméricas não forneceu evidências de processos de fusão recentes envolvendo os cariomorfos. Com relação aos elementos transponíveis foi possível verificar padrões distintos nos elementos TC1 e Rex1 no que diz respeito às sequências, uma vez que o elemento TC1 delimitou dois grandes grupos o que pode indicar uma invasão simultânea nos grupos e no retrotransposon Rex1 a invasão tenha ocorrido em um ancestral comum a todos os cariomorfos / The repetitive DNA constitutes a considerable fraction of the genome of many eukaryotic organisms. Compound by both functional sequences, such as ribosomal genes, and non-coding, such as transposable elements, mini / microsatellite DNA and the satellite, this portion of the genome has been widely used as a study object, since the repetitive sequences may be associated with, for example, the processes of sexual differentiation. These studies helped to understand the dynamics of these chromosomal regions, pointing the importance, conservation and evolution of the repetitive portion of the genome. The genus Eigenmannia (Gymnotiformes, Sternopygidae) comprises a morphological cryptic species that exhibit variation in chromosome number and may have sexual XY or ZW systems in which the elements of sexual pair differ by the presence of heterochromatic blocks larger than those found in chromosomes autosomes, or systems involving multiple Y-autosome translocation. The present work aims to study the gene Cytochrome Oxidase I (COI) to verify the discriminatory capacity of this mitochondrial gene and suggest possible species of the so called karyomorphs of the genus Eigenmannia in the state of São Paulo. The study of repetitive DNA in Eigenmannia genus, includes 5S ribosomal gene and transposable elements, thus allowing a better understanding of the distribution, conservation in karyomorphs and verify their possible participation in the process of differentiation not only of sex chromosomes, karyotypic evolution but also in the group. The results obtained with the COI gene, as well as those obtained by the 5S ribosomal gene demonstrate genetic distances consistent with the hypothesis that the five karyomorphs can be regarded as separate species. In addition, in situ hybridization of ribosomal 5S gene provided new evidence for chromosomal fusion which led to the Y sex chromosome, as described in the literature, whereas hybridization of telomeric sequences did not provide evidence of recent fusion events involving the karyomorphs. Regarding transposable elements, it could be verified distinct sequence patterns between TC1 and Rex1 elements, since the TC1 element delimited two groups which may indicate a simultaneously invasion in those groups and retrotransposon Rex1 invasion has occurred in a common ancestor to all karyomorphs

Employee turnover is a complex problem with many intertwining contributors. In general newly hired employees at an organization have a higher risk of injury. However, few studies have explored occupational injury as a predictor of employment duration. In this study we hypothesized that employees who sustained an injury during the early stages of employment were prone to higher turnover rates. All employees hired from 2012-2016 were identified using a large Midwestern manufacturing facilities human resources database (n=3765). Corresponding occupational injury information from the same time period was extracted from the onsite occupational health center. Employment duration was the dependent variable which was dichotomized as (i) working < 60 days or (ii) working ≥60 days. The 60-day threshold was based on the employer’s internal estimation of the duration of employment required to recover training costs. The primary independent variable was a first-time visit to the occupational health center within the first 60 days of employment, categorized as (i) no visit, (ii) a visit within 1-20 days, or (iii) a visit within 21-60 days. A secondary independent variable incorporated the nature of injury, classified as repetitive strain, acute sprain/strain, or other occupational injury types. Covariates included demographics (e.g., age, gender, and race/ethnicity), shift placement (e.g. first, second, third), and nature of assigned job (e.g., assembly, fabrication, maintenance). Incidence rates of first-time visits were calculated (i) across the full study period and (ii) for a reduced period that included only the first 60 days of employment. Logistic regression was used to estimate adjusted associations between the primary/secondary independent variables and the dependent variable. Of the 3765 employees, 1184 (31.5%) worked less than 60 days. About two-thirds were male, about half were white/Caucasian, and the overall mean age was 33.8±10.8 years. Between 2012 and 2016, 1105 first-time visits to the occupational health center were recorded for all new hires with an overall incidence rate (IR) of 47/100 person-years (PY). The IR for repetitive strain was 18/100PY. Of the 1105 first-time visits, 408 occurred within the first 60 days of employment with an overall IR of 85/100PY and an IR for repetitive strain of 36/100PY. Employees who visited the occupational health center in the first 20 days of employment were more likely to terminate prior to the 60-day threshold (adjusted odds ratio: 1.7; 95% confidence interval: 1.3-2.4). Elevated associations were seen for all nature of injury categories which occurred within 20 days when compared to non-injured employees. Overall, the results suggest that experiencing an occupational injury (in particular, a repetitive strain injury) within the first 20 days of employment is associated with termination before 60 days. Our results may not be generalizable to all manufacturing enterprises, and we do not make a distinction between voluntary and involuntary termination. However, the results indicate that employers should examine policies and practices to minimize the burden of injury among new employees and reduce turnover. In the case of the study facility, an extended or modified work hardening program could maximize new employees’ adaptation to the physical demands of manufacturing work.

Despite their homology and analogous function, the Hox gene clusters of vertebrates and invertebrates are subject to different constraints on their structural organization. This is demonstrated by a drastically different distribution of repetitive DNA elements in the Hox cluster regions. While gnathostomes have a strong tendency to exclude repetitive DNA elements from the inside of their Hox clusters, no such trend can be detected in the Hox gene clusters of protostomes. Repeats “invade” the gnathostome Hox clusters from the 5′ and 3′ ends while the core of the clusters remains virtually free of repetitive DNA. This invasion appears to be correlated with relaxed constraints associated with gene loss after cluster duplications.

The impact of raising a child with autism spectrum disorder (ASD) is frequently accompanied by elevated caregiver stress. Examining the variables that predict these elevated rates will help us understand how caregiver stress is impacted by and impacts child behaviors. This study explored how restricted and repetitive behaviors (RRBs) contributed concurrently and longitudinally to caregiver stress in a large sample of preschoolers with ASD using parallel process multilevel growth models. Results indicated that initial rates of and change in RRBs predicted fluctuations in caregiver stress over time. When caregivers reported increased child RRBs, this was mirrored by increases in caregiver stress. Our data support the importance of targeted treatments for RRBs as change in this domain may lead to improvements in caregiver wellbeing.

<p> The possible contribution of neural plasticity to ON, OFF and steady state responses elicited by brief, repetitive trains of stimulation was investigated in the intact human subject with the use of the electroencephalogram (EEG). Experiment One implemented trains of stimulation at three different repetition rates, 1.5Hz, 4Hz and 13Hz. The goal was to investigate the nature of the ON, OFF and steady state responses evoked at these repetition rates. The experiment was carried out in three modalities: visual (n=13), auditory (n=lO) and somatosensory (n=12). The main result was that the ON and OFF responses were enhanced at 13Hz compared to the lower repetition rates. Experiment Two sought to answer the question of whether enhancement depended on the repetition rate or the increased experience provided by the higher frequencies. The number of stimuli in the 13Hz trains was reduced to equal the 1.5Hz condition from Experiment One. Graded exposure was then provided to the 13Hz stimulation. This procedure was implemented in two groups of subjects: Replication One (n=12) used 13Hz stimulation and Replication Two (n=24) used 14Hz stimulation. A subset (n=IO) of the Replication Two subjects returned for a second session (Day 2) 24 hours after the first. An assessment of effects was made after minutes and hours. There were four main results. The OFF response was observed after nine 13Hz pulses and did not change over the course of the experiment. The ON response increased with exposure to the 13Hz trains. Steady state responses diminished and showed a phase shift over the experimental session. Results for Day 1 and Day 2 were not different. Within session changes, as a result of exposure to the stimulus, were seen. These effects were not long lasting. </p> / Thesis / Master of Science (MSc)

No description available.

Despite the advances in modern technology, unraveling the genome evolution of an organism or even groups of several species remains a challenging task. Up-to-date cytogenetics and computational approaches enable the investigation of genomes from the nucleotide sequence up to the chromosomes, yet, drawing conclusions about evolutionary and mechanistic processes remains far from being trivial. The crop sugar beet (<i>Beta vulgaris</i> subsp. <i>vulgaris</i>) and its wild relatives form a well-suited group of plants (members of the Amaranthaceae family) to demonstrate the possibilities and limits that both, cytological and computational genomics, possess in addressing open questions on the genome in a phylogenetic context and in all its conformations: from its organization in chromosomes right down to the loss and gain of genes and the composition of repetitive DNA sequences. Since the two beet genera <i>Beta</i> and <i>Patellifolia</i> comprise diploid as well as polyploid species, genomic variability between them is not only based on DNA sequence differences, but on changes in the chromosome number as well. In the frame of this work, using microscopic approaches (outlined in chapter II), it was determined that all beets share a base chromosome number of x = 9. Differing properties between cultivated and wild beet accessions are the result of polyploidization and changes in the DNA sequence rather than a restructuring of the chromosomes. In chapter III, the focus is on the tetraploid wild beet <i>Beta corolliflora</i>, whose polyploidization likely led to the development of many tolerances against adverse environmental conditions. Since its ancestry remained unresolved for a long time, five different bioinformatics tools have been developed and complemented with cytogenetics to unravel its parental relationships. As an ‘autopolyploid’ hybrid descending from closely related <i>Beta macrorhiza</i> accessions, <i>B. corolliflora</i> occupies an intermediate position within the spectrum of auto- to allopolyploidy. Today’s breeding endeavors aim for the (re-)introduction of genes from wild beet into cultivated beet accessions to improve crop species in the face of changing cultivation conditions. Yet, such efforts are impeded due to crossing barriers, reflected in the separation of the beet species into three distinct gene pools. Chapter IV aims to identify repetitive DNA sequences that may be involved in speciation and formation of these gene pools. For this, genome data has been generated for a panel of 17 different beet accessions and was analyzed bioinformatically as well as experimentally, using long and short read technology, fluorescent <i>in situ</i> and Southern hybridization. The overall repeat content was found to correlate with the beet genome sizes and whereas some repeats are well conserved among the beet species, the specificity of others mirrors the split into the three beet gene pools. Satellite DNAs in particular vary considerably between beet genomes, leading to the evolution of distinct chromosomal setups in the three gene pools with uniform centromeres in the primary and tertiary gene pool and patchwork centromeres in the secondary gene pool, likely contributing to the barriers in beet breeding. Furthermore, endogenous sequences of viral origin were also detected in all beet genomes with specific elements for the different beet gene pools. As for <i>B. vulgaris</i>, these endogenous pararetroviruses were found to contribute to the host’s defense against other (putatively harmful) viruses (chapter V). In summary, this thesis demonstrates the synergistic potential of integrating computational and cytological genomics for a comprehensive genome analysis of beets that can be transferred to any other species panel. Combining both approaches enables to unlock a deeper understanding of the genetic makeup and evolution of the species of interest, in particular with regard to the impact of repetitive elements. / Trotz des technologischen Fortschritts bleibt die Entschlüsselung der Evolution eines Genoms oder gar der Genome mehrerer Arten eine anspruchsvolle Aufgabe. Moderne zytogenetische und computergestützte Ansätze ermöglichen die Untersuchung von Genomen von der Nukleotidsequenz bis hin zu den Chromosomen. Trotzdem ist es alles andere als trivial, daraus Rückschlüsse auf evolutionäre und mechanistische Prozesse zu ziehen. Die Zuckerrübe (<i>Beta vulgaris</i> subsp. <i>vulgaris</i>) und ihre wilden Verwandten stellen eine Pflanzengruppe aus der Familie der Amaranthaceae dar, die sich gut dafür eignet, Möglichkeiten und Grenzen der zytologischen sowie computergestützten Genomik aufzuzeigen. Bei der Beantwortung offener Fragen zum Genom in einem phylogenetischen Kontext werden dabei all seine Ausprägungen in Betracht gezogen: von der Genomorganisation in Chromosomen bis hin zum Verlust und Erhalt von Genen und der Zusammensetzung repetitiver DNA-Sequenzen. Da die beiden Rübengattungen <i>Beta</i> und <i>Patellifolia</i> sowohl diploide als auch polyploide Arten umfassen, beruht die genomische Variabilität zwischen den Rübengenomen nicht nur auf Unterschieden in der DNA-Sequenz, sondern auch auf Veränderungen in der Chromosomenzahl. Im Rahmen der vorliegenden Arbeit wurde mit Hilfe mikroskopischer Methoden (siehe Kapitel II) festgestellt, dass alle Rüben eine Basischromosomenzahl von n = 9 aufweisen. Unterschiedliche Eigenschaften zwischen kultivierten und wilden Rüben-Akzessionen sind das Ergebnis von Polyploidisierung und Veränderungen in der DNA-Sequenz und nicht von chromosomalen Umstrukturierungen. In Kapitel III liegt der Fokus auf der tetraploiden Wildrübe <i>Beta corolliflora</i>, deren Polyploidisierung wahrscheinlich zahlreiche Toleranzen gegenüber widrigen Umweltbedingungen bedingt. Da ihre Abstammung lange Zeit ungeklärt blieb, wurden fünf verschiedene bioinformatische Methoden entwickelt und zytogenetisch komplementiert, um die Elternspezies zu entschlüsseln. So handelt es sich bei <i>B. corolliflora</i> wahrscheinlich um eine „autopolyploide“ Hybride, die von eng verwandten <i>Beta macrorhiza</i>-Akzessionen abstammt und eine Zwischenform im Spektrum der Polyploidie darstellt. Heutige Züchtungsansätze zielen auf die (Wieder-)Einführung von Genen aus Wildrüben in kultivierte Rübensorten ab, um die Kulturarten angesichts der sich ändernden Anbaubedingungen widerstandsfähiger und/oder ertragreicher zu machen. Solche Bemühungen werden jedoch durch Kreuzungsbarrieren eingeschränkt, die sich in der Gruppierung der Rübenarten in drei verschiedene Genpools widerspiegeln. Kapitel IV zielt darauf ab, repetitive DNA-Sequenzen zu identifizieren, die möglicherweise an Adaption und Artbildung beteiligt sind. Genomdaten wurden für 17 verschiedene Rüben-Akzessionen generiert und sowohl bioinformatisch als auch experimentell mittels Fluoreszenz-<i>in situ</i>- und Southern-Hybridisierung analysiert. Der Gesamtgehalt an repetitiven DNA-Sequenzen korreliert mit der Genomgröße der Rübenakzessionen. Während einige repetitive DNA-Sequenzen zwischen den Rübenarten konserviert sind, spiegelt die Spezifität anderer die Aufteilung in die drei Rübengenpools wider. Insbesondere die Satelliten-DNA variiert beträchtlich zwischen den Rübengenomen, was zur Entwicklung unterschiedlicher chromosomaler Strukturen in den drei Genpools geführt hat: Der primäre und tertiäre Genpool sind hierbei durch einheitlichen Zentromere gekennzeichnet, während sich der sekundäre Genpool durch eine individuelle Zentromerzusammensetzung auszeichnet, die von Chromosom zu Chromosom verschieden sein kann. Dies trägt wahrscheinlich zu den Hindernissen im Zuge der Rübenzucht bei. Außerdem wurden in allen Rübengenomen endogene Sequenzen viralen Ursprungs nachgewiesen, die für die verschiedenen Rübengenpools spezifisch sind. Für <i>B. vulgaris</i> wurde festgestellt, dass diese endogenen Pararetroviren zur Verteidigung gegen andere (ggf. schädliche) Viren beitragen (Kapitel V). Zusammenfassend zeigt diese Arbeit das synergistische Potenzial einer Integration der computergestützten und zytologischen Genomik für eine umfassende Genomanalyse von Rüben auf, die auf jedes andere Artenpanel übertragen werden kann. Die Kombination beider Ansätze ermöglicht ein tieferes Verständnis des Genoms und der Evolution der betreffenden Art, insbesondere in Hinblick auf den Einfluss repetitiver DNA-Sequenzen.

The overarching aim of this research was to understand factors implicated in the maintenance of rumination and worry, conceptualised as a transdiagnostic process of repetitive negative thought (RNT), through the use of cross-sectional, prospective, and experimental research designs. Rumination and worry have been repeatedly implicated in the development and maintenance of various forms of psychopathology, in particular, depression and anxiety disorders. Given the negative outcomes for mood and psychopathology, there is a need for a better understanding of vulnerability factors that maintain this unconstructive thinking. Based on a review of the literature, an integrative theoretical model was developed and tested using structural equation modelling. Using cross-sectional data, the model was tested in a large sample of adults (n = 506). Of the broad range of proximal and distal vulnerability factors examined, only neuroticism and beliefs about the function of repetitive thought remained significantly associated with RNT once current symptoms were statistically controlled. Emotional abuse and abstract processing were indirectly associated with RNT. Following on from this, a prospective study examined which of these vulnerability factors prospectively predicted change in RNT over six to eight weeks. Only neuroticism and the specific belief that repetitive thought aids instrumental understanding predicted change in RNT, after controlling for depression and anxiety symptoms. Next, two experimental studies were conducted to explore the causal relationship between RNT and the belief that RNT aids insight and understanding, by experimentally manipulating this appraisal and measuring the impact on state RNT. Whilst methodological issues with the first experimental study precluded clear conclusions being drawn about the nature of the relationship, the second experimental study demonstrated that participants manipulated to believe that RNT is helpful for increasing insight and understanding had greater levels of state RNT after exposure to a stressor, relative to participants manipulated to believe that RNT is unhelpful. Finally, in order to see whether rumination has any consequences that may potentially reinforce its further use, an experimental study was conducted to manipulate processing mode (abstract rumination versus concrete thinking) and examine the effect on a range of outcomes relating to insightfulness and avoidance. Whilst rumination did not lead to increased insight, it did afford more justification for avoidance, relative to concrete thinking. The clinical and theoretical implications of these findings are discussed with respect to existing theories of repetitive negative thought.

Background and Objectives: Rumination may contribute to depression by impairing the most effective allocation of time across activities. An experiment tested the role of rumination in time allocation across tasks. Methods: State rumination was manipulated by cueing an unresolved goal in one condition (32 participants) and cueing a resolved goal in another condition (32 participants). Trait rumination and depressive symptoms were also measured. All participants completed two word generation tasks and allocated a fixed overall time budget between the tasks by interleaving between them. Results: No difference was found in task performance or time allocation following the manipulation of state rumination. Self-reported rumination did not differ between conditions throughout the experimental task. Differences in time allocation behaviour were associated with trait rumination. Limitations: Use of a non-clinical population and tasks that are unrepresentative of everyday problem solving limited the generalisability of the results and may have limited the effect of the state rumination manipulation on task performance. Conclusions: The absence of a difference in self-reported rumination throughout the task suggests that either the word generation task reduced levels of rumination or that the level of rumination induced did not have a large effect on the cognitive processes required to complete the word generation task.